Craze-resistant transparent resinous polymodal block copolymers
FIELD OF THE INVENTION 
     The invention pertains to resinous copolymers. In one aspect, the invention pertains to resinous copolymers which are craze-resistant and transparent with minimal coloration. In a further aspect, the invention pertains to methods of sequential block copolymerization for the preparation of craze-resistant, low-color resinous copolymers. In another aspect, the invention pertains to methods of producing block copolymer resins which are transparent, possess good mechanical properties, particularly impact resistance, are not susceptible to flexural stress clouding, and yet are transparent with minimal coloration. 
     BACKGROUND OF THE INVENTION 
     Resinous block copolymers have been produced by methods employing various sequential polymerization steps. Among the pioneer inventions in the field of resinous block copolymers are such patents as U.S. Pat. No. 3,639,517 to Kitchen and Szalla, U.S. Pat. No. 4,080,407 to Fodor, and U.S. Pat. No. 4,091,053 to Kitchen. 
     Much effort has been directed to the preparation of substantially transparent block copolymer resins with a variety of block structures produced by a variety of monomer addition sequences. 
     However, products frequently have had residual coloration tinges, or the impact strength has been low, or importantly for many purposes there has been a high incidence of crazing (flexural stress clouding). 
     One of the more important applications for transparent resinous copolymers has been in blister packaging of bandages, syringes, and the like for contained product protection and maintenance of sterile conditions during shipping. Unfortunately, all too frequently, crazing of the blister packs has occurred because of squeezing during shipping. The crazed packs, plus their valuable contents, then must be discarded by the recipients, such as hospitals or physicians, since it is presumed that air has leaked into the pack and that the contents have lost their sterility due to contamination. 
     Other usages of the transparent resinous polymers have been for blending with general purpose polystyrene. The transparent resinous polymers have been used for various molding purposes. However, many of the so-formed products have had a bluish tinge, or lacked clarity because of haze, frequently leading to customer objection and reluctance to purchase. 
     Needed, still, are resinous copolymers, readily made, impact resistant, exhibiting a high resistance to crazing, transparent with good clarity, substantially no color, and substantially haze-free. 
     BRIEF SUMMARY OF THE INVENTION 
     I have discovered resinous block copolymers which are highly craze-resistant, transparent, and substantially color-free. I have also discovered methods of producing these highly desirable craze-resistant non-blue, non-hazy, transparent block copolymers. 
     A haze of less than 3 is considered good, and of about 2 or less very good, per ASTM 1003 on a 50 mil thick sample (see my Table VI herein). Substantial freedom from craze is desired (see my Table VI herein). 
     It is an object of my invention to provide resinous block copolymers which in use are substantially craze-resistant and exhibit minimal coloration, retaining a haze-free character, particularly in thin sheet products. It is another object of my invention to provide methods for producing these highly desirable resinous copolymers. 
     The polymers are characterized as resinous, polymodal, copolymers of at least one conjugated diene with at least one monovinylarene, and are prepared so that at least a portion of the final product is of a coupled character, linear or radial or both. The copolymers contain about 55 to 95, preferably 60 to 87, more preferably 70 to 80, percent by weight of copolymerized monovinyl aromatic compound (monovinylarene), and correspondingly about 45 to 5, 40 to 13, or 30 to 27, percent by weight of copolymerized conjugated diene. The coupled portions of the resinous, polymodal copolymers have terminal polymonovinylarene blocks on the extending arms of each linear or radial copolymer molecule, and further contain a central internal block of polyconjugated diene, ignoring any interruption of the internal block by a coupling agent residue. The resinous copolymeric polymodal products also contain portions of linear uncoupled block copolymers of poly(monovinylarene)-poly(conjugated diene), which content is considered to be an important portion of the resinous product, important that is in its overall properties. 
     The copolymers are prepared by a process of sequential charge copolymerization comprising the solution polymerization of at least two charges each of a conjugated diene monomer, a monovinylarene monomer, and a monoalkali metal initiator, at least one charge of conjugated diene monomer precedes the last charge of alkali metal initiator, at least one charge each of monovinylarene and of conjugated diene follow the last charge of monoalkali metal initiator, and the last charge of monomer is a charge of conjugated diene, such that the number of charges of each of the three components is not more than three, and the total of the charges of the three components is 8 or 9. Each monomer charge is allowed to polymerize to substantial completion prior to the next monomer charge (if any). 
     The resinous, polymodal block copolymers can be prepared by various modifications (modes) of the above general procedure. Table I following shows the preferred sequences, compared with prior art sequences and control modes. In Table I, the indicated Runs refer to exemplary Runs in my Examples included herein in my specification. The differences in result are significant, my inventive products being more craze-resistant and having less coloration than the comparative products. 
     
                                           TABLE I
__________________________________________________________________________
         Invention      Comparisons
         Mode A
              Mode B
                   Mode C
                        Runs
Charge   Runs Runs Runs 9-10-11-
                             Runs Example
Order    1-2-3
              4-5-6
                   7-8  12-13-14
                             15-16-17
                                  VII
__________________________________________________________________________
1/2      L/S* L/S* L/S* L/S* L/S* L/S*
3        B    B    --   --   --   --
4/5      L/S* S    L/S* S    S    S
6        B    B    B    --   B    --
7/8      L/S* L/S* L/S* L/S* L/S* S
9        B    B    B    B    B    B
(Total additions)
         (9)  (8)  (8)  (6)  (7)  (5)
10       C    C    C    C    C    C
__________________________________________________________________________
 *either L or S are charged first, then the other, or effectively
 substantially at the same time; presently preferred is charge of initiato
 prior to monomer.
 where L = monoalkali metal initiator.
 S = monovinylarene monomer and the resultant polymer block.
 B = conjugated diene monomer and the resultant polymer block.
 C = coupling agent.
 
    
     In Table I, &#34;L&#34; refers to any monoalkali metal initiator useful in solution polymerization systems; &#34;S&#34; refers to a monovinylarene monomer and to the resultant polymonovinylarene block formed by the substantially complete polymerization of the monovinylarene monomer added at the indicated stage; &#34;B&#34; indicates a conjugated diene monomer and the resultant polyconjugated diene block formed from the substantially complete polymerization of the conjugated diene monomer added at that stage; and &#34;C&#34; indicates a coupling agent. 
     Table II following indicates further the relationship of my inventive sequences compared to the other methods as to the number of additions of alkali metal initiator, conjugated diene, and monovinylarene prior to coupling: 
     
                                           TABLE II
__________________________________________________________________________
Number of Additions of Each Component
        Invention      Comparisons
        Mode A
             Mode B
                  Mode C
                       Runs   Runs
        Runs Runs Runs 9-10-11
                              15-16-
        1-2-3
             4-5-6
                  7-8  12-13-14-19
                              17-18
                                  Example VII
__________________________________________________________________________
L       3    2    3    2      2   1
S       3    3    3    3      3   3
B       3    3    2    1      2   1
Total Additions
        9    8    8    6      7   5
__________________________________________________________________________
 
    
     As can be seen from Table II above, comparisons employ three additions of monovinylarene (such as styrene), only a single or two additions of conjugated diene monomer (such as butadiene), and, only one or two additions of monoalkali metal initiator. Thus, my products and processes are distinguished therefrom, and are improved thereover, by using at least two additions of conjugated diene monomer as well as at least two, and preferably three, additions of monoalkali metal initiator, in a prescribed sequence as disclosed hereinabove, and as exemplified by my Examples hereinafter set forth. 
     In accordance with one aspect (mode) of my invention, the following copolymeric species are considered to be formed prior to coupling in accordance with the sequence of addition of monomers and initiator: 
     Mode A 
     S 1  -B 1  -S 2  -B 2  -S 3  -B 3  -L 
     S 2  -B 2  -S 3  -B 3  -L 
     S 3  -B 3  -L. 
     Each of &#34;S 1  &#34;, &#34;S 2  &#34;, and &#34;S 3  &#34; indicates a block of substantially homopolymeric polymonovinylarene, formed in appropriate sequence by addition of the monovinylarene monomer and polymerization thereof under solution polymerization conditions such that substantially complete polymerization of the monomer charge is obtained before the next step of monomer or initiator addition, if any. Each of &#34;B 1  &#34;, &#34;B 2  &#34;, and &#34;B 3  &#34;  similarly represents a block of substantially homopolymeric poly(conjugated diene) similarly formed in appropriate sequence by polymerization of the charge to substantial completion prior to the next step or charge. The subscript numbers indicate which step evolved the block or blocks. Each &#34;L&#34; indicates a residue from a monoalkali metal initiator remaining on the end of the polymerization chain prior to termination. The &#34;L&#34; subsequently is removed or displaced during coupling and/or termination when the above species groups form various combinations of coupled copolymeric species. My methods thus effectively provide broad polymodal benefits. 
     In another aspect (mode) of my invention, the following copolymeric species are considered to be formed prior to coupling: 
     Mode B 
     S 1  -B 1  -S 2  -B 2  -S 3  -B 3  -L 
     S 3  -B 3  -L. 
     In the third aspect of my invention, presently more preferred than Modes A and B, the following species are expected to be formed prior to coupling: 
     Mode C 
     S 1  -S 2  -B 1  -S 3  -B 2  -L 
     S 2  -B 1  -S 3  -B 2  -L 
     S 3  -B 2  -L. 
     The final resinous polymodal product resulting from the polymerization procedure of the prescribed series of steps of additions of monomer/initiator/coupling also result in proportions of terminated uncoupled species which escape coupling. 
     Of course, in addition to the sequence of addition of the monomers and of the initiator, it is important to control the amount of each monomer and initiator addition under each sequence above at each increment so that a suitable proportion of block sizes and proportion of polymodality is obtained in each mode. It is feasible to stretch out over an interval of time the addition of one or more of the increments of initiator and/or the input of the appropriate monovinylarene monomer charge, thus spreading (increasing) further the polymodality of the resulting product upon coupling. 
     Tables III following describe broad and preferred increments of monomers and of monoalkali metal initiator, using L to symbolize the monoalkali metal indicator, S for monovinylarene, and B for conjugated diene. 
     
                       TABLES III
______________________________________
Ranges of Monomers and of Initiator Additions at each Increment
                 Broad   Preferred
______________________________________
Mode A
Step IA   L-1 (phm).sup.(1) (2)
                        0.02-0.035
                                 0.022-0.03
          L-1 (mhm).sup.(3) (4)
                        0.3-0.55 0.34-0.47
          S-1 (phm)    30-45     35-41
Step IB   B-1 (phm)    0.6-9     2-4
Step IIA  L-2 (phm)     0.02-0.035
                                 0.022-0.03
          L-2 (mhm)     0.3-0.55 0.34-0.47
          S-2 (phm)    10-20     12-18
Step IIB  B-2 (phm)    0.6-9     2-4
Step III  L-3 (phm)    0.07-0.18  0.1-0.15
          L-3 (mhm)    1.1-2.8   1.56-2.34
          S-3 (phm)    15-30     18-26
Step IV   B-3 (phm)    3.8-27    16-23
Totals    S (phm)      55-95     70-80
          B (phm)      45-5      30-20
          L (phm)       0.1-0.25 0.13-0.2
          L (mhm)      1.7-3.9   2.2-3.3
______________________________________
Mode B
Step IA   L-1 (phm)    0.025-0.05
                                 0.03-0.04
          L-1 (mhm)    0.39-0.78 0.47-0.63
          S-1 (phm)    30-45     35-40
Step IIB  B-1 (phm)    0.6-9     2-4
Step IIA  S-2 (phm)    10-20     13-18
Step IIB  B-2 (phm)    0.6-9     2-4
Step III  L-2 (phm)     0.1-0.25 0.12-0.17
          L-2 (mhm)    1.56-3.9  1.88-2.66
          S-3 (phm)    15-30     18-25
Step IV   B-3 (phm)    3.8-27    15-23
Totals    S (phm)      55-95     70-80
          B (phm)      45-5      30-20
          L (phm)      0.13-0.25 0.15-0.22
          L (mhm)       2.-4.7   2.3-3.4
______________________________________
MODE C
Step IA   L-1 (phm)    0.02-0.04 0.024-0.035
          L-1 (mhm)     0.3-0.63 0.38-0.55
          S-1 (phm)    30-45     35-40
Step IIA  L-2 (phm)    0.02-0.04 0.025-0.035
          L-2 (mhm)     0.3-0.63 0.38-0.55
          S-2 (phm)    10-20     12-18
Step IIB  B-1 (phm)    1.2-18    4-8
Step III  L-3 (phm)    0.06-0.18  0.08-0.014
          L-3 (mhm)    0.94-2.8  1.25-2.19
          S-3 (phm)    15-30     20-25
Step IV   B-2 (phm)    3.8-27    15-22
Totals    S (phm)      55-95     70-80
          B (phm)      45-5      30-20
          L (phm)       0.1-0.26 0.13-0.2
          L (mhm)      1.5-4       2-3.3
______________________________________
 .sup.(1) phm = parts by weight per 100 parts by weight of total monomers.
 .sup.(2) phm for L is based only on nbutyllithium molecular weight.
 .sup.(3) mhm = grammillimoles per 100 grams of total monomers.
 .sup.(4) mhm for L is applicable for any monoalkali metal initiator. The
 levels suggested are exclusive of requirements for any poisons in the
 solvent streams, such as traces of alcohols.
 
    
     Based on the above monomer additions, assuming substantially complete (co)polymerization of each monomer increment added at each step before proceeding to the next step, and assuming equivalent rates of initiation and propagation, the following relative Block Sizes Prior to Coupling can be calculated (in which phm≡weight percent) as shown below in Tables IV: 
     
                       TABLES IV
______________________________________
Calculated Relative Block Sizes Before Coupling
Calculated from Ranges of Monomer Additions
                  Broad  Preferred
______________________________________
Mode A
(1)   S.sub.1 --B.sub.1 --S.sub.2 --B.sub.2 --S.sub.3 --B.sub.3 :
      S.sub.1 (phm)     30-45    35-41
      B.sub.1 (phm)     0.6-9    2-4
      S.sub.2 (phm)      5-10    6-9
      B.sub.2 (phm)     0.3-4.5  1-2
      S.sub.3 (phm)     2.6-4.2  2.7-3.7
      B.sub.3 (phm)     0.7-3.8  2.4-3.3
(2)   S.sub.2 --B.sub.2 --S.sub.3 --B.sub.3 :
      S.sub.2 (phm)      5-10    6-9
      B.sub.2 (phm)     0.3-4.5  1-2
      S.sub.3 (phm)     2.6-4.2  2.7-3.7
      B.sub.3 (phm)     0.7-3.8  2.4-3.3
(3)   S.sub.3 --B.sub.3 :
      S.sub.3 (phm)      9.7-21.6
                                 12.5-18.5
      B.sub.3 (phm)      2.4-19.4
                                 11.1-16.4
      After Coupling:
      M.sub.w × 10.sup.-3(1)
                         80-300  150-200
      M.sub.n × 10.sup.-3(1)
                         50-200   90-120
______________________________________
Mode B
(1)   S.sub.1 --B.sub.1 --S.sub.2 --B.sub.2 --S.sub.3 --B.sub.3 :
      S.sub.1 (phm)     30-45    35-40
      B.sub.1 (phm)     0.6-9    2-4
      S.sub.2 (phm)     10-20    13-18
      B.sub.2 (phm)     0.6-9    2-4
      S.sub.3 (phm)     3-5      3.6-4.8
      B.sub.3 (phm)     0.8-4.5    3-4.4
(2)   S.sub.3 --B.sub.3 :
      S.sub.3 (phm)     12-25    14.4-20.2
      B.sub.3 (phm)       3-22.5   12-18.6
      After Coupling
      M.sub.w × 10.sup.-3
                         80-300  140-200
      M.sub.n × 10.sup.-3
                         50-200   90-120
______________________________________
Mode C
(1)    S.sub.1 --S.sub.2 --B.sub.1 --S.sub.3 --B.sub.2 :
      S.sub.1 (phm)     30-45    35-40
      S.sub.2 (phm)      5-10    6-9
      B.sub.1 (phm)     0.6-9    2-4
      S.sub.3 (phm)       3-4.6  3.8-4.2
      B.sub.2 (phm)     0.7-4.2  2.8-3.7
(2)   S.sub.2 --B.sub.1 --S.sub.3 --B.sub.2 :
      S.sub.2 (phm)      5-10    6-9
      B.sub.1 (phm)     0.6-9    2-4
      S.sub.3 (phm)       3-4.6  3.8-4.2
      B.sub.2 (phm)     0.7-4.2  2.8-3.7
(3)   S.sub.3 --B.sub.2 :
      S.sub.3 (phm)       9-20.7 12.4-16.6
      B.sub.2 (phm)      2.4-18.6
                                  9.3-14.6
      After Coupling:
      M.sub.w × 10.sup.-3
                         80-300  150-200
      M.sub.n × 10.sup.-3
                         50-200   90-120
______________________________________
 .sup.(1) M.sub.w = weight average molecular weight.
 .sup.(2) M.sub.n = number average molecular weight.
 
    
     Monomers 
     The conjugated dienes employed ordinarily are those of 4 to 6 carbon atoms per molecule, including the presently preferred 1,3-butadiene, as well as isoprene, 2-ethyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, and piperylene, alone or in admixture. 
     The monovinylarenes employed alone or in admixture, ordinarily contain 8 to 10 carbon atoms per molecule, including the presently preferred styrene, as well as α-methylstyrene, p-vinyltoluene, m-vinyltoluene, o-vinyltoluene, 4-ethylstyrene, 3-ethylstyrene, 2-ethylstyrene, 4-tert-butylstyrene, and 2,4-dimethylstyrene. 
     Polymerization 
     The solution process polymerization is carried out as is known in the art in a hydrocarbon diluent at any suitable temperature such as in the range of about -100° to 150° C., more usually about 0° to 110° C., at a pressure sufficient to maintain the reaction mixture substantially as a liquid. Preferred are cycloparaffins, alone or in admixture with such as pentane or isooctane. Presently preferred is cyclohexane. As is known, small amounts of polar compounds, such as tetrahydrofuran, can be included in the diluent for vinyl control of the diene polymer blocks, and/or to improve effectiveness of some initiators such as the primary alkyllithium initiators for monovinylarene polymerizations. 
     The initiators can be any of the organomonoalkali metal compounds known for such purposes. Preferably employed are the hydrocarbylmonoalkali metal compounds which correspond to the formula RM in which R is a hydrocarbyl aliphatic, cycloaliphatic, or aromatic radical, preferably alkyl, and M is an alkali metal, preferably lithium. Presently preferred are alkylmonolithium initiators such as sec- and n-butyllithium. The amounts of monoalkali metal-based initiator employed depends upon the desired polymer or incremental block molecular weight as is known in the art, and are readily determinable from my ranges given above, making due allowance for traces of poisons in the feed streams. 
     The polymerization is conducted in the substantial absence of air or moisture, preferably under an inert atmosphere. The resulting polymers contain a very high percentage of molecules in which an alkali metal atom is positioned at an end of the polymer chains. Of course, traces of impurities present in the feeds, such as water or alcohol, tend to reduce the amount of monoalkali metal-terminated polymer formed. Thereafter, a coupling step is performed. 
     Coupling Reaction 
     In my use of the term &#34;coupling&#34; as herein employed, the term means the bringing together and joining, by means of one or more central coupling atoms or coupling moieties, two or more of the living monoalkali metal-terminated polymer chains. A wide variety of compounds for such purposes can be employed. 
     Among the suitable coupling agents are the di- or multivinylaromatic compounds, di- or multiepoxides, di- or multiisocyanates, di- or multiimines, di- or multialdehydes, di- or multiketones, di- or multihalides, particularly silicon halides and halosilanes mono-, di-, or multianhydrides, mono-, di-, or multiesters, preferably the esters of monoalcohols with polycarboxylic acids, diesters which are esters of monohydric alcohols with dicarboxylic acids, lactones, and the like, including combination type compounds containing two or more groups, and mixtures. 
     Examples of suitable vinylaromatic coupling agents include divinylbenzene, 1,2,4-trivinylbenzene, 1,3-divinylnaphthalene, 1,3,5-trivinylnaphthalene, 2,4-divinylbiphenyl, and the like. Of these, the divinylaromatic hydrocarbons are preferred, particularly divinylbenzene in either its ortho, meta, or para isomer. Commercial divinylbenzene which is a mixture of the three isomers and other compounds is satisfactory. 
     While any di- or multiepoxide can be used, those which are liquid are convenient since they are more readily handled and form a relatively small nucleus for a radial polymer. Epoxidized hydrocarbon polymers such as epoxidized liquid polybutadiene and the epoxidized vegetable oils such as epoxidized soybean oil and epoxidized linseed oil, and epoxy compounds such as 1,2; 5,6; 9,10-triepoxydecane, and the like, can be used. 
     Examples of suitable multiisocyanates include benzene-1,2,4-triisocyanate, naphthalene-1,2,5,7-tetraisocyanate, and the like. Commercially available products known as PAPI-1, a polyarylpolyisocyanate having an average of 3 isocyanate groups per molecule and an average molecular weight of about 380 are suitable. 
     The multiimines, also known as multiaziridinyl compounds, such as those containing 3 or more aziridine rings per molecule, are useful. Examples include the triaziridinyl phosphine oxides or sulfides such as tri(1-aziridinyl)phosphine oxide, tri(2-methyl-1-aziridinyl)phosphine oxide, tri(2-ethyl-3-decyl-1-aziridinyl)phosphine sulfide, and the like. 
     The multialdehydes are represented by compounds such as 1,4,7-naphthalenetricarboxyaldehyde, 1,7,9-anthracenetricarboxyaldehyde, 1,1,5-pentanetricarboxyaldehyde, and similar multialdehyde-containing aliphatic and aromatic compounds. The multiketones are represented by compounds such as 1,4,9,10-anthracenetetrone, 2,3-diacetonylcyclohexanone, and the like. Examples of the multianhydrides include pyromellitic dianhydride, styrene-maleic anhydride copolymers, and the like. Examples of the multiesters include diethyladipate, triethylcitrate, 1,3,5-tricarbethoxybenzene, and the like. 
     Among the multihalides are the silicon tetrahalides such as silicon tetrachloride, silicon tetrabromide, and silicon tetraiodide; the trihalosilanes such as trifluorosilane, trichlorosilane, trichloroethylsilane, tribromobenzylsilane, and the like; and the multihalogen-substituted hydrocarbons, such as 1,3,5-tri(bromomethyl)benzene, 2,5,6,9-tetrachloro-3,7-decadiene, and the like, in which the halogen is attached to a carbon atom which is alpha to an activating group such as an ether linkage, a carbonyl group, or a carbon-to-carbon double bond. Substituents inert with respect to lithium atoms in the terminally reactive polymer can also be present in the active halogen-containing compounds. Alternatively, other suitable reactive groups different from the halogen as described above can be present. 
     Examples of compounds containing more than one type of functional group include 1,3-dichloro-2-propanone, 2,2-dibromo-3-decanone, 3,5,5-trifluoro-4-octanone, 2,4-dibromo-3-pentanone, 1,2,4,5-diepoxy-3-pentanone, 1,2; 4,5-diepoxy-3-hexanone, 1,2; 11,12-diepoxy-8-pentadecanone, 1,3; 18,19-diepoxy-7,14-eicosanedione, and the like. 
     Other metal multihalides, particularly those of tin, lead, or germanium, can be employed as coupling and branching agents. Silicon or other metal multialkoxides, such as silicon tetraethoxide, are also suitable coupling agents. 
     Any effective amount of the coupling agent can be employed. While the amount is not believed to be particularly critical, a stoichiometric amount relative to the active polymer-alkali metal tends to promote maximum coupling as a generality. However, less than stoichiometric amounts can be used for lesser degrees of coupling where desired for particular products of broadened molecular weight. 
     Typically, the total amount of coupling agent is in the range of about 0.1 to 20 mhm (gram millimoles per 100 grams of total monomers employed in the polymerization), presently preferably about 0.1 to 1 mhm (or about 0.1 to 1 phm). Preferred at present is an epoxidized soybean oil. 
     Polymer Recovery 
     Following completion of the coupling reaction, the coupled polymer, which may still contain bound alkali metal atoms depending on the type of coupling agent employed, is treated to remove any remaining alkali metal from the copolymer and to recover the copolymer. 
     The polymer cement (polymer in polymerization solvent) from polymerization usually contains about 10 to 40, more usually 20 to 30, weight percent solids, the balance solvent. Preferably, but not necessarily, the polymer cement is flashed to remove by evaporation a portion of the solvent so as to reduce the solvent content to a concentration of about 10 to 50, more usually about 30 to 40, weight percent (corresponding to a solids content of about 90 to 50, more usually about 70 to 60, weight percent). 
     The polymer cement from polymerization, optionally concentrated by flashing, then is treated by various means, as is known in the art, such as by carbon dioxide and water, or treated with an aliphatic linear α,ω-dibasic acid, such as disclosed in U.S. Pat. No. 4,403,074, and recovered such as by separation and drying. 
     The resinous copolymeric products can be, and normally are, compounded with anti-oxidants, anti-blocking agents, release agents, and the like, as known in the compounding arts. 
     The resinous polymodal in situ made copolymer products can be blended with general purpose polystyrene. Broad ranges include such as about 5-90 weight percent polystyrene, more usually 10-40 weight percent polystyrene, the balance one or more of my polymodal resinous impact resistant copolymer products. 
    
    
     EXAMPLES 
     Examples following are intended to further illustrate my invention. Particular species employed, relationships, ratios, conditions, should be considered as a part of my overall disclosure without being limiting of the reasonable scope of my invention. 
     EXAMPLE I 
     These data describe the preparation of inventive coupled, resinous, polymodal butadiene-styrene copolymers employing three n-butyllithium (NBL) initiator charges, three styrene charges, and three 1,3-butadiene charges, total 9, prior to coupling. Butadiene, styrene, and NBL were employed as representative of the conjugated dienes, monovinylarenes, and monoalkali metal initiators, respectively. 
     Polymerization runs were carried out under nitrogen in a stirred, jacketed, stainless steel reactor of two gallons capacity employing essentially anhydrous reactants and conditions. Recipes 1, 2, and 3 were used for the preparation of ten representative, inventive, resinous copolymer samples: 
     
         ______________________________________
Recipe 1
           Run 1A Run 1B   Run 1C   Run 1D
______________________________________
Step IA
Cyclohexane  150      150      150    150
diluent, phm.sup.(1)
Tetrahydrofuran, phm
              0.025    0.025    0.025  0.025
Styrene, phm 37       37       37     37
n-Butyllithium, phm
              0.025    0.025    0.025  0.025
Polymerization
             12       12       13     12
Time, min.
Polymerization,
             139→167
                      126→156
                               148→167
                                      140→154
Temp..sup.(2), °F.
Reactor Pressure, psig
             21→30
                      25→30
                               26→30
                                      25→30
Step IB
Cyclohexane.sup.(3), phm
             6.7      6.7      6.7    6.7
1,3-Butadiene, phm
              3        3        3      3
Polymerization
             15       15       21     17
Time, min.
Polymerization
             161      151      160    159
Temp., °F.
Reactor Pressure, psig
             30       30       30     30
Step IIA
Cyclohexane, phm
             13.3     13.3     13.3   13.3
n-Butyllithium, phm
              0.025    0.025    0.025  0.025
Styrene, phm 16       16       16     16
Polymerization
             10       10        9     10
Time, min.
Polymerization
             148→165
                      150→163
                               155→161
                                      156→151
Temp., °F.
Reactor Pressure, psig
             30→35
                      31→35
                               30→31
                                      30→35
Step IIB
Cyclohexane, phm
             6.7      6.7      6.7    6.7
1,3-Butadiene, phm
              3        3        3      3
Polymerization
             15       16       22     18
Time, min.
Polymerization
             165      163      161    165
Temp., °F.
Reactor Pressure, psig
             35       35       31     35
Step III
Cyclohexane, phm
             13.3     13.3     13.3   13.3
n-Butyllithium, phm
              0.11     0.11     0.11   0.11
Styrene, phm 23       23       23     23
Polymerization
             10       11       16     10
Time, min.
Polymerization
             150→174
                      144→165
                               144→161
                                      145→179
Temp., °F.
Reactor Pressure, psig
             30→50
                      30→50
                               30→50
                                      20→50
Step IV
Cyclohexane, phm
             6.7      6.7      6.7    6.7
1,3-Butadiene, phm
             18       18       18     18
Polymerization
             20       14       19     20
Time, min.
Polymerization
             174→218
                      164→216
                               161→215
                                      179→218
Temp., °F.
Reactor pressure, psig
             50       50       50     50
Step V (Coupling)
Cyclohexane, phm
             6.7      6.7      6.7    6.7
Admex 711.sup.(4), phm
             0.4      0.4      0.4    0.4
Coupling Time, min.
             20       20       20     20
Coupling Temp., °F.
             218      216      215    218
Reactor Pressure, psig
             50       50       50     50
Step VI (Recovery)
Water, phm    0.22     0.22     0.22   0.22
CO.sub.2, psi.sup.(5)
             120      120      120    120
Termination  13       15       --     --
Time, psig
Termination  218      218      219    220
Temp., °F.
Reactor pressure, psig
             100      100      50     50
Recovered Resin
Flow Rates.sup.(6),
             5.9      9.0      7.9    7.0
g/10 min.
Added Anti-   1.25     1.25     1.25   1.25
oxidant.sup.(7), wt. %
Added Wax.sup.(8), wt. %
              0.25     0.25     0.25   0.25
Butadiene:Styrene
             24:76    24:76    24:76  24:76
Wt. Ratio
______________________________________
 .sup.(1) Parts by weight per 100 parts by weight of total monomer.
 .sup.(2) The temperatures listed for Steps IA, IB, IIA, IIB, III, and IV
 are the recorded initial and final polymerization temperatures; the highe
 peak temperatures were not recorded.
 .sup.(3) Small amounts of cyclohexane were used in each step (except Step
 VI) to flush the feed lines
 .sup.(4) Epoxidized soybean oil; molecular weight: 980-1000; density: 1.0
 g/cc; marketed by Sherex Co., Dublin, Ohio.
 .sup.(5) The amount of CO.sub.2 employed was that amount from a 350 ml
 container pressurized to 120 psig; about 1.4 grams, or about 0.1 phm.
 .sup.(6) Determined at 200° C. according to ASTM D1238, Condition
 G, employing a total weight of 5.0 kg.
 .sup.(7) Tris(nonylphenyl)phosphite (TNPP), 1 wt. %; Irganox 1076, 0.25
 wt. %.
 .sup.(8) &#34;Be Square&#34; microcrystalline wax 195 marketed by Bareco, a Div.
 of Petrolite Corp., Tulsa, Oklahoma; used as an antioblocking agent.
 
    
     
         ______________________________________
Recipe 2
              Run 2A   Run 2B   Run 2C
______________________________________
Step IA
Cyclohexane, phm
                150        150      150
Tetrahydrofuran, phm
                 0.025      0.025    0.025
Styrene, phm    40         40       40
n-Butyllithium, phm
                 0.027      0.027    0.027
Polymerization Time, min.
                12         12       11
Polymerization, Temp., °F.
                130→161
                           132→167
                                    134→167
Reactor Pressure, psig
                28→30
                           25→32
                                    25→30
Step IB
Cyclohexane, phm
                6.7        6.7      6.7
1,3-Butadiene, phm
                 3          3        3
Polymerization Time, min.
                15         19       17
Polymerization Temp., °F.
                156        162      161
Reactor Pressure, psig
                30         32       30
Step IIA
Cyclohexane, phm
                13.3       13.3     13.3
n-Butyllithium, phm
                 0.025      0.025    0.025
Styrene, phm    13         13       13
Polymerization Time, min.
                11         10       10
Polymerization Temp., °F.
                147→161
                           152→160
                                    150→164
Reactor Pressure, psig
                30→32
                           30→32
                                    30→32
Step IIB
Cyclohexane, phm
                6.7        6.7      6.7
1,3-Butadiene, phm
                  3         3        3
Polymerization Time, min.
                17         15       15
Polymerization Temp., °F.
                161        160      164
Reactor Pressure, psig
                32         32       32
Step III
Cyclohexane, phm
                13.3       13.3     13.3
n-Butyllithium, phm
                 0.12       0.12     0.12
Styrene, phm    23         23       23
Polymerization Time, min.
                10         14       10
Polymerization Temp., °F.
                141→171
                           148→164
                                    145→176
Reactor Pressure, psig
                30→50
                           30→50
                                    30→50
Step IV
Cyclohexane, phm
                6.7        6.7      6.7
1,3-Butadiene, phm
                18         18       18
Polymerization Time, min.
                15         22       20
Polymerization Temp., °F.
                171→213
                           164→219
                                    176→217
Reactor pressure, psig
                50         50       50
Step V (Coupling)
Cyclohexane, phm
                6.7        6.7      6.7
Admex 711, phm  0.4        0.4      0.4
Coupling Time, min.
                20         20       20
Coupling Temp., °F.
                213        219      217
Reactor Pressure, psig
                50         50       50
Step VI (Recovery)
Water, phm       0.22       0.22     0.22
CO.sub.2, psi   120        120      120
Termination Time, psig
                13         14       15
Termination Temp., °F.
                217        219      219
Reactor Pressure, psig
                100        100      100
Recovered Resin
Flow Rate, g/10 min.
                6.4        6.6      6.8
Added Antioxidant, wt. %
                 1.25       1.25     1.25
Added Wax, wt. %
                 0.25       0.25     0.25
Butadiene:Styrene Wt. Ratio
                24:76      24:76    24:76
______________________________________
 Footnotes to Recipe 1 also apply to Recipe 2.
 
    
     
         ______________________________________
Recipe 3
              Run 3A   Run 3B   Run 3C
______________________________________
Step IA
Cyclohexane, phm
                150        150      150
Tetrahydrofuran, phm
                 0.025      0.025    0.025
Styrene, phm    40         40       40
n-Butyllithium, phm
                 0.027      0.027    0.027
Polymerization Time, min.
                12         12       12
Polymerization, Temp., °F.
                136→165
                           156→166
                                    136→165
Reactor Pressure, psig
                29→30
                           25→30
                                    25→30
Step IB
Cyclohexane, phm
                6.7        6.7      6.7
1,3-Butadiene, phm
                 3          3        3
Polymerization Time, min.
                15         15       15
Polymerization Temp.,°F.
                158        162      161
Reactor Pressure, psig
                30         30       30
Step IIA
Cyclohexane, phm
                13.3       13.3     13.3
n-Butyllithium, phm
                 0.025      0.025    0.025
Styrene, phm    13         13       13
Polymerization Time, min.
                10         10       10
Polymerization Temp., °F.
                151→166
                           151→162
                                    153→164
Reactor Pressure, psig
                30→41
                           30→35
                                    30→31
Step IIB
Cyclohexane, phm
                6.7        6.7      6.7
1,3-Butadiene, phm
                 3          3        3
Polymerization Time, min.
                14         16       15
Polymerization Temp., °F.
                166        162      164
Reactor Pressure, psig
                41         35       31
Step III
Cyclohexane, phm
                13.3       13.3     13.3
n-Butyllithium, phm
                 0.13       0.13     0.13
Styrene, phm    21         21       21
Polymerization Time, min.
                15         14       10
Polymerization Temp., °F.
                154→161
                           152→171
                                    147→169
Reactor Pressure, psig
                30→51
                           30→50
                                    30→50
Step IV
Cyclohexane, phm
                6.7        6.7      6.7
1,3-Butadiene, phm
                20         20       20
Polymerization Time, min.
                19         20       20
Polymerization Temp., °F.
                161→218
                           171→219
                                    169→215
Reactor pressure, psig
                50         50       50
Step V (Coupling)
Cyclohexane, phm
                6.7        6.7      6.7
Admex 711, phm  0.4        0.4      0.4
Coupling Time, min.
                20         20       19
Coupling Temp., °F.
                218        219      215
Reactor Pressure, psig
                50         50       50
Step VI (Recovery)
Water, phm       0.22       0.22     0.22
CO.sub.2, psi   120        120      120
Termination Time, psig
                30         18       22
Termination Temp., °F.
                220        220      218
Reactor Pressure, psig
                100        100      100
Recovered Resin
Flow Rate, g/10 min.
                7.2        7.0      7.2
Added Antioxidant, wt. %
                 1.25       1.25     1.25
Added Wax, wt. %
                 0.25       0.25     0.25
Butadiene:Styrene Wt. Ratio
                24:74      24:74    24:74
______________________________________
 Footnotes to Recipe 1 also apply to Recipe 3.
 
    
     EXAMPLE II 
     These data describe the preparation of coupled, resinous, polymodal butadiene-styrene copolymers employing two n-butyllithium initiator charges, three styrene charges, and three 1,3-butadiene charges, total 8, prior to coupling. Recipes 4, 5, and 6 were used for the preparation of seven representative, inventive resinous copolymers similarly as described in Example I. 
     
         ______________________________________
Recipe 4
              Run 4A   Run 4B   Run 4C
______________________________________
Step IA
Cyclohexane, phm
                157        157      157
Tetrahydrofuran, phm
                 0.025      0.025    0.025
Styrene, phm    37         37       37
n-Butyllithium, phm
                 0.032      0.032    0.032
Polymerization Time, min.
                13         13       11
Polymerization, Temp., °F.
                140→159
                           143→162
                                    130→158
Reactor Pressure, psig
                28→30
                           29→30
                                    25→30
Step IB
Cyclohexane, phm
                6.7        6.7      6.7
1,3-Butadiene, phm
                 3          3        3
Polymerization Time, min.
                15         15       15
Polymerization Temp., °F.
                154        159      154
Reactor Pressure, psig
                30         30       30
Step IIA
Cyclohexane, phm
                6.7        6.7      6.7
n-Butyllithium, phm
                none       none     none
Styrene, phm    16         16       16
Polymerization Time, min.
                11         12       10
Polymerization Temp., °F.
                153        156      149
Reactor Pressure, psig
                30         32       30
Step IIB
Cyclohexane, phm
                6.7        6.7      6.7
1,3-Butadiene, phm
                 3          3        3
Polymerization Time, min.
                22         15       22
Polymerization Temp., °F.
                168        39       166
Reactor Pressure, psig
                35         39       35
Step III
Cyclohexane, phm
                13.3       13.3     13.3
n-Butyllithium, phm
                 0.15       0.15     0.15
Styrene, phm    23         23       23
Polymerization Time, min.
                17         13       15
Polymerization Temp., °F.
                148→170
                           153→173
                                    146→162
Reactor Pressure, psig
                30→50
                           30→50
                                    30→50
Step IV
Cyclohexane, phm
                6.7        6.7      6.7
1,3-Butadiene, phm
                18         18       18
Polymerization Time, min.
                18         20       20
Polymerization Temp., °F.
                170→219
                           173→219
                                    162→216
Reactor pressure, psig
                50         50       50
Step V (Coupling)
Cyclohexane, phm
                6.7        6.7      6.7
Admex 711, phm  0.4        0.4      0.4
Coupling Time, min.
                20         20       17
Coupling Temp., °F.
                219        219      216
Reactor Pressure, psig
                50         50       50
Step VI (Recovery)
Water, phm       0.22       0.22     0.22
CO.sub.2, psi   120        120      120
Termination Time, psig
                24         15       22
Termination Temp., °F.
                221        220      219
Reactor Pressure, psig
                100        100      100
Recovered Resin
Flow Rate, g/10 min
                4.9        3.9      5.2
Added Antioxidant, wt. %
                 1.25       1.25     1.25
Added Wax, wt. %
                 0.25       0.25     0.25
Butadiene:Styrene Wt. Ratio
                24:76      24:76    24:76
______________________________________
 Footnotes to Recipe 1 also apply to Recipe 4.
 
    
     
         ______________________________________
           Recipe 5    Recipe 6
           Run 5A Run 5B   Run 6A   Run 6B
______________________________________
Step IA
Cyclohexane, phm
             157      157      157    157
Tetrahydrofuran, phm
              0.025    0.025    0.025  0.025
Styrene, phm 37       37       37     37
n-Butyllithium, phm
              0.035    0.035    0.030  0.032
Polymerization
             20       28       16     18
Time, min.
Polymerization,
             134→151
                      127→154
                               125→150
                                      129→154
Temp., °F.
Reactor Pressure, psig
             29→30
                      29→30
                               25→31
                                      25→30
Step IB
Cyclohexane, phm
             6.7      6.7      6.7    6.7
1,3-Butadiene, phm
              3        3        3      3
Polymerization
             15       15       15     20
Time, min.
Polymerization
             142      145      146    152
Temp., °F.
Reactor Pressure, psig
             32       30       31     30
Step IIA
Cyclohexane, phm
             13.3     13.3     13.3   13.3
n-Butyllithium, phm
             none     none     none   none
Styrene, phm 16       16       16     16
Polymerization
             15       15       18     15
Time, min.
Polymerization
             142→159
                      141→160
                               145→157
                                      150→161
Temp., °F.
Reactor pressure, psig
             32→35
                      31→40
                               35     30→32
Step IIB
Cyclohexane, phm
             6.7      6.7      6.7    6.7
1,3-Butadiene, phm
              3        3        3      3
Polymerization
             14       15       15     15
Time, min.
Polymerization
             159      160      157    161
Temp., °F.
Reactor Pressure, psig
             35       40       35     32
Step III
Cyclohexane, phm
             13.3     13.3     13.3   13.3
n-Butyllithium, phm
              0.12     0.14     0.15   0.14
Styrene, phm 21       21       21     21
Polymerization
             15       17       17     16
Time, min.
Polymerization
             146→162
                      145→163
                               145→161
                                      147→162
Temp., °F.
Reactor Pressure, psig
             30→50
                      30→50
                               30→50
                                      31→50
Step IV
Cyclohexane, phm
             6.7      6.7      6.7    6.7
1,3-Butadiene, phm
             20       20       20     20
Polymerization
             20       20       15     20
Time, min.
Polymerization
             162→218
                      163→217
                               161→215
                                      162→218
Temp., °F.
Reactor pressure, psig
             50       50       50     50
Step V (Coupling)
Cyclohexane, phm
             6.7      6.7      6.7    6.7
Admex 711, phm
             0.4      0.4      0.4    0.4
Coupling Time, min.
             20       20       20     20
Coupling Temp., °F.
             218      217      215    218
Reactor Pressure, psig
             50       50       50     50
Step VI (Recovery)
Water, phm    0.22     0.22     0.22   0.22
CO.sub.2, psi
             120      120      120    120
Termination  26       18       19     20
Time, psig
Termination  221      222      219    220
Temp., °F.
Reactor Pressure, psig
              70→100
                       70→100
                               100    100
Recovered Resin
Flow Rate,   7.6      10.2     6.2    6.5
g/10 min.
Added Anti-   1.25     1.25     1.25   1.25
oxidant, wt. %
Added Wax, wt. %
              0.25     0.25     0.25   0.25
Butadiene:Styrene
             26:74    26:74    26:74  26:74
Wt. Ratio
______________________________________
 Footnotes to Recipe 1 also apply to Recipes 5 and 6.
 
    
     EXAMPLE III 
     These data describe the preparation of coupled, resinous, polymodal butadiene-styrene copolymers employing three n-butyllithium charges, three styrene charges, and two 1,3-butadiene charges, total 8, prior to coupling. Recipes 7 and 8 were used for the preparation of seven representative, inventive, resinous copolymer samples similarly as described in Example I. 
     
         ______________________________________
Recipe 7
           Run 7A Run 7B   Run 7C   Run 7D
______________________________________
Step IA
Cyclohexane, phm
             157      157      157    157
Tetrahydrofuran, phm
              0.025    0.025    0.025  0.025
Styrene, phm 37       37       37     37
n-Butyllithium, phm
              0.030    0.030    0.030  0.030
Polymerization
             14       14       15     14
Time, min.
Polymerization
             134→152
                      126→151
                               132→152
                                      126→147
Temp., °F.
Reactor Pressure, psig
             29→30
                      29→30
                               25→30
                                      25→30
Step IB
Cyclohexane, phm
             --       --       --     --
1,3-Butadiene, phm
             none     none     none   none
Polymerization
             --       --       --     --
Time, min.
Polymerization
             --       --       --     --
Temp., °F.
Reactor Pressure, psig
             --       --       --     --
Step IIA
Cyclohexane, phm
             13.3     13.3     13.3   13.3
n-Butyllithium, phm
              0.030    0.030    0.030  0.030
Styrene, phm 16       16       16     16
Polymerization
             12       12       12     12
Time, min.
Polymerization
             172→159
                      159→162
                               159→164
                                      156
Temp., °F.
Reactor Pressure, psig
             30→32
                      30→35
                               30→35
                                      30→32
Step IIB
Cyclohexane, phm
             6.7      6.7      6.7    6.7
1,3-Butadiene, phm
              6        6        6      6
Polymerization
             24       12       15     25
Time, min.
Polymerization
             159      162      164    156
Temp., °F.
Reactor Pressure, psig
             32       35       35     32
Step III
Cyclohexane, phm
             13.3     13.3     13.3   13.3
n-Butyllithium, phm
              0.11     0.10     0.10   0.10
Styrene, phm 23       23       23     23
Polymerization
             12       12       12     12
Time, min.
Polymerization
             147→164
                      153→183
                               148→169
                                      143→171
Temp., °F.
Reactor Pressure, psig
             30→50
                      30→50
                               30→50
                                      20→50
Step IV
Cyclohexane, phm
             6.7      6.7      6.7    6.7
1,3-Butadiene, phm
             18       18       18     18
Polymerization
             20       20       20     20
Time, min.
Polymerization
             164→217
                      183→217
                               169→217
                                      171→217
Temp., °F.
Reactor Pressure, psig
             50       50       50     50
Step V (Coupling)
Cyclohexane, phm
             6.7      6.7      6.7    6.7
Admex 711, phm
             0.4      0.4      0.4    0.4
Coupling Time, min.
             15       15       15     15
Coupling Temp., °F.
             217      217      217    217
Reactor Pressure, psig
             50       50       50     50
Step VI (Recovery)
Water, phm    0.22     0.22     0.22   0.22
CO.sub.2, psi
             120      120      120    120
Termination  18       15        8     18
Time, psig
Termination  219      219      219    219
Temp., °F.
Reactor Pressure, psig
             100      100      100    100
Recovered Resin
Flow Rate, g/10 min.
             8.4      6.9      7.3    7.1
Added Anti-   1.25     1.25     1.25   1.25
oxidant, wt. %
Added Wax, wt. %
              0.25     0.25     0.25   0.25
Butadiene:Styrene
             24:76    24:76    24:76  24:76
Wt. Ratio
______________________________________
 Footnotes to Recipe I also apply to Recipe 7.
 
    
     
         ______________________________________
Recipe 8
              Run 8A   Run 8B   Run 8C
______________________________________
Step IA
Cyclohexane, phm
                157        157      157
Tetrahydrofuran, phm
                 0.025      0.025    0.025
Styrene, phm    37         37       37
n-Butyllithium, phm
                 0.030      0.030    0.030
Polymerization Time, min.
                13         15       17
Polymerization, Temp., °F.
                136→155
                           156→157
                                    131→152
Reactor Pressure, psig
                26→30
                           29→32
                                    29→30
Step IB
Cyclohexane, phm
                --         --       --
1,3-Butadiene, phm
                none       none     none
Polymerization Time, min.
                --         --       --
Polymerization Temp., °F.
                --         --       --
Reactor Pressure, psig
                --         --       --
Step IIA
Cyclohexane, phm
                13.3       13.3     13.3
n-Butyllithium, phm
                 0.030      0.030    0.030
Styrene, phm    16         16       16
Polymerization Time, min.
                12         15       12
Polymerization Temp., °F.
                167→159
                           167→156
                                    164→154
Reactor Pressure, psig
                30→31
                           30→31
                                    30
Step IIB
Cyclohexane, phm
                6.7        6.7      6.7
1,3-Butadiene, phm
                 6          6        6
Polymerization Time, min.
                10         15       17
Polymerization Temp., °F.
                30         31       30
Reactor Pressure, psig
                30         31       30
Step III
Cyclohexane, phm
                13.3       13.3     13.3
n-Butyllithium, phm
                 0.12       0.11     0.11
Styrene, phm    22         22       22
Polymerization Time, min.
                15         15       12
Polymerization Temp., °F.
                160→50
                           147→165
                                    143→175
Reactor Pressure, psig
                30→50
                           30→50
                                    30→50
Step IV
Cyclohexane, phm
                6.7        6.7      6.7
1,3-Butadiene, phm
                19         19       19
Polymerization Time, min.
                17         20       20
Polymerization Temp., °F.
                164→218
                           165→219
                                    175→218
Reactor Pressure, psig
                50         50       50
Step V (Coupling)
Cyclohexane, phm
                6.7        6.7      6.7
Admex 711, phm  0.4        0.4      0.4
Coupling Time, min.
                15         15       15
Coupling Temp., °F.
                218        219      218
Reactor Pressure, psig
                50         50       50
Step VI (Recovery)
Water, phm       0.22       0.22     0.22
CO.sub.2, psi   120        120      120
Termination Time, psig
                20         23       14
Termination Temp., °F.
                220        220      220
Reactor Pressure, psig
                100        100      105
Recovered Resin
Flow Rate, g/10 min.
                9.0        7.5      7.6
Added Antioxidant, wt. %
                 1.25       1.25     1.25
Added Wax, wt. %
                 0.25       0.25     0.25
Butadiene:Styrene Wt. Ratio
                25:75      25:75    25:75
______________________________________
 Footnotes to Recipe 1 also apply to Recipe 8.
 
    
     EXAMPLE IV 
     In this example, typical recipes for preparing coupled, resinous, polymodal, butadiene-styrene control resins, essentially in accordance with the procedure given in Example I of U.S. Pat. No. 3,639,517, are described. Recipes 9, 10, and 11 list average polymerization parameters of numerous representative control runs: 
     
         ______________________________________
Control Recipes 9, 10, and 11
              Run 9   Run 10    Run 11
______________________________________
Step IA
Cyclohexane, phm
                167       167       167
Tetrahydrofuran, phm
                 0.025     0.025     0.025
Styrene, phm    33        33        33
n-Butyllithium, phm
                0.030-0.034
                          0.030-0.034
                                     0.030
Polymerization Time, min.
                15-20     15-20     17-20
Polymerization, Temp., °F.
                110-170   110-170   110-170
Reactor Pressure, psig
                30        30        30
Step IB
Cyclohexane, phm
                --        --        --
1,3-Butadiene, phm
                none      none      none
Polymerization Time, min.
                --        --        --
Polymerization Temp., °F.
                --        --        --
Reactor Pressure, psig
                --        --        --
Step IIA
Cyclohexane, phm
                6.7       6.7       6.7
n-Butyllithium, phm
                none      none      none
Styrene, phm    20        20        15
Polymerization Time, min.
                15-20     15-20     15-20
Polymerization Temp., °F.
                140-180   140-180   140-180
Reactor Pressure, psig
                30-40     30-40     30-40
Step IIB
Cyclohexane, phm
                --        --        --
1,3-Butadiene, phm
                none      none      none
Polymerization Time, min.
                --        --        --
Polymerization Temp., °F.
                --        --        --
Reactor Pressure, psig
                --        --        --
Step III
Cyclohexane, phm
                13.3      13.3      13.3
n-Butyllithium, phm
                0.12-0.14 0.12-0.14 0.14
Styrene, phm    23        23        26
Polymerization Time, min.
                15-20     15-20     15-20
Polymerization Temp., °F.
                140-180   140-180   140-180
Reactor Pressure, psig
                30-40     30-40     30-40
Step IV
Cyclohexane, phm
                6.7       6.7       6.7
1,3-Butadiene, phm
                24        24        26
Polymerization Time, min.
                15-20     15-20     15-20
Polymerization Temp., °F.
                100-225   100-225   150-225
Reactor pressure, psig
                30-50     30-50     30-50
Step V (Coupling)
Cyclohexane, phm
                6.7       6.7       6.7
Admex 711, phm   0.40     0.40      0.40
Coupling Time, min.
                10-15     10-15     10-15
Coupling Temp., °F.
                215-225   215-225   215-225
Reactor Pressure, psig
                40-50     40-50     40-50
Step VI (Recovery)
Water, phm       0.22     0.22      0.22
CO.sub.2, psi   120       120       120
Termination Time, psig
                10-15     10-15     10-15
Termination Temp., °F.
                210-220   210-220   210-220
Reactor Pressure, psig
                 50-100    50-100    50-100
Recovered Resin
Flow Rate, g/10 min.
                --        --        --
Added Antioxidant, wt. %
                 1.25     1.25      1.25
Added Wax, wt. %
                 0.25     0.25      0.25
Butadiene:Styrene Wt. Ratio
                24:76     24:76     26:74
______________________________________
 Footnotes to Recipe 1 also apply to Recipes 9, 10, and 11.
 
    
     EXAMPLE V 
     In this Example, physical properties of the coupled, polymodal, butadiene-styrene resins prepared in accordance with Recipes 1 through 11 inclusive are described. Approximately equal amounts of resins prepared in equivalent runs (about 3 lb per run) were blended by first manually shaking the portions of resins together in a carton drum for about 1 minute and then feeding the mixture through a grinder to produce the blend. Prepared blends are listed in Table V: 
     
                                           TABLE V
__________________________________________________________________________
Resin Runs for Preparing
                 Bd.:Styr.
                       Flow
                           M.sub.w.sup.(3) ×
                                M.sub.n.sup.(3) ×
Blend Blend Components
                 Wt. Ratio
                       Rate
                           10.sup.-3
                                10.sup.-3
__________________________________________________________________________
Resin 1
      Runs 1A, 1B, 1C, 1D
                 24:76 7.4 158   93
Resin 2
      Runs 2A, 2B, 2C
                 24:76 7.3 189  114
Resin 3
      Runs 3A, 3B, 3C
                 26:74 6.7 188  112
Resin 4
      Runs 4A, 4B, 4C
                 24:76 4.1 186   99
Resin 5
      Runs 5A, 5B
                 26:74 8.3 157   96
Resin 6
      Runs 6A, 6B
                 26:74 6.2 177  100
Resin 7
      Runs 7A, 7B, 7C, 7D
                 24:76 7.5 174  115
Resin 8
      Runs 8A, 8B, 8C
                 24:76 8.2 173  109
Resin 9
      Seven Run 9 resins
                 24:76 6.3 .sup.  --.sup.(1)
                                --
Resin 10
      Eight Run 10 resins
                 24:76 7.3 --   --
Resin 11
      Three Run 11 resins
                 26:74 7.4 --   --
Resin 12
      Control Resin.sup.(2)
                 24:76 7.7 170-200
                                90-120
Resin 13
      Control Resin.sup.(2)
                 24:76 8.4 170-200
                                90-120
Resin 14
      Control Resin.sup.(2)
                 24:76 7.7 170- 200
                                90-120
__________________________________________________________________________
 .sup.(1) a dash indicates not determined.
 .sup.(2) commercially available, coupled, resinous butadienestyrene
 copolymer, prepared essentially in accordance with Recipes 9 and 10;
 marketed by Phillips Chemical Co., Bartlesville, OK, as KResin ® resi
 KRO3.
 .sup.(3) weight average molecular weight (M.sub.w) and number average
 molecular weight (M.sub.n), as determined from gel permeation
 chromatography curves according to the procedure described by G. Kraus an
 C. Stacy in J. Poly. Sci. A2, 10, 657 (1972) and J. Poly. Sci. Symposium
 No. 43,329 (1973); actual molecular weights are in thousands, e.g., resin
 has M.sub.w of 158,000.
 
    
     The dry-mixed blends were molded in an Arburg 221 E/150, 11/2 ounce molding machine at a barrel temperature of about 210° C., a mold temperature of about 50° C., a screw speed setting of about 200, an injection pressure ranging from about 54 to 57 KP/cm 2 , and a total cycle time of 35 seconds. Physical properties of molded specimens are listed in Table VI: 
     
                                           TABLE VI
__________________________________________________________________________
                         Gardner Impact.sup.(4)
                                    Tensile    Flex  Defl..sup.(7)
         Hunter Haze.sup.(2)
                          (cm. kg)  Strength.sup.(5)
                                          Elong..sup.(5)
                                               Modulus.sup.(6)
                                                     Temp.
                                                         Hardness.sup.(8)
                                                         2
Resin    &#34;b&#34; Value.sup.(1)
                %   Craze.sup.(3)
                         Disk
                            Bowl
                                Sheet
                                    (Yield, psi)
                                          (%)  (psi) (°F.)
                                                         (Shore
__________________________________________________________________________
                                                         D)
 1 (Invention)
         -3.0   1.8 No   -- 12.0
                                1.2 4910  289  193,000
                                                     176 73
 2 (Invention)
         -4.7   1.7 No   116
                            5.0 1.5 4420  282  189,000
                                                     172 71
 4 (Invention)
         -4.7   2.1 No    99
                            4.4 1.4 4450  285  183,000
                                                     181 70
 7 (Invention)
         -2.5   0.9 No    93
                            39.0
                                2.0 4420  300  196,000
                                                     185 68
 8 (Invention)
         -3.8   0.7 No    91
                            47.0
                                1.5 4040  289  192,000
                                                     181 69
 9 (Control)
         -11.6  1.9 Yes  106
                            --  1.2 4720  210  241,000
                                                     209 67
10 (Control)
         -11.1  1.7 Yes  103
                            --  1.0 4570  214  239,000
                                                     209 67
12 (Control)
         -12.2  1.3 Yes  111
                            3.8 1.5 4600  241  247,000
                                                     194 67
13 (Control)
         -17.2  3.6 Yes  -- 3.2 14.8
                                    4250  204  230,000
                                                     188 65
14 (Control)
         -10.8  1.4 Yes  101
                            8.8 8.8 4700  249  247,000
                                                     193 67
 3 (Invention)
         -5.2   2.1 No   114
                            42.0
                                2.1 4180  282  176,000
                                                     173 67
 5 (Invention)
         -5.5   1.2 No   120
                            --  1.0 4257  316  196,000
                                                     195 72
 6 (Invention)
         -8.7   1.8 No   120
                            --  1.1 4019  276  187,000
                                                     194 72
11 (Control)
         -15.1  1.7 Yes   95
                            --  --  4210  221  223,000
                                                     206 65
__________________________________________________________________________
 .sup.(1) tristumulus value &#34;b&#34; is a measure of blue and yellow tint: -b =
 blue m, +b = yellow; measured with a Hunter Lab Color Difference Meter 25
 DM using injection molded (350° F./30 tons/2 minutes) resin disks
 of 0.15 inch thickness and 2.5 inch diameter. Measurements were against a
 black background.
 .sup.(2) determined with a Gardner hazemeter according to ASTM 1003, usin
 test specimens of 50 mil thickness.
 .sup.(3) determined by visual inspection of the ductile indentation made
 on an injection molded disk 0.05 inch thick when impacted in a Gardner
 Impact Test using a 4 lb round dart (about 0.5 inch diameter) dropped fro
 a height of 15-20 inches.
 .sup.(4) determined according to Instruction Manual IG1120 Gardner
 Laboratories, using a 4 lbweight; thickness of disk (injection molded at
 210° C.): 0.05 inch; thickness of bowl (injection molded at
 210° C.): 0.05 inch; thickness of sheet (extruded at 177° C
 on a Kinney extruder, at a shear rate of 450 sec.sup.-1 : 0.01 inch; disk
 were edge gated, bowls were center gated.
 .sup.(5) determined according to ASTM D638.
 .sup.(6) determined according to ASTM D790.
 .sup.(7) Vicat deflection temperature, determined according to ASTM D648.
 .sup.(8) determined according to ASTM D2240.
 
    
     Data in Table VI clearly show at least two significant improvements in properties of my Inventive Resins Runs 1-8 inclusive vs. control resins Runs 9-12: less blue color (lower negative Hunter &#34;b&#34; value), and no crazing and opaqueness upon impact. Tensile strength and hardness were comparable for inventive and control resins, whereas flexural modulus tended to be somewhat lower for inventive polymers, though not undesirably so. The Vicat deflection temperatures seemed to trend slightly lower for the inventive resins. Gardner impact of disks is comparable for inventive and control resins; bowl impact is generally higher for inventive resins, while sheet impact is lower for inventive resins. Based on bowl impact data, Resins 7 and 8 prepared with three n-butyllithium initiator charges, three styrene charges, and two butadiene charges, total 9 before coupling, presently are most preferred. 
     EXAMPLE VI 
     In this example the polymerization and properties of control resins Runs 15-19 inclusive are described. 
     Control Resins 15-18 inclusive which were prepared with two n-butyllithium (NBL) initiator charges, three styrene charges, and two butadiene charges. The recipes for Control Runs 15-18 were essentially the same as the recipes for Control Runs 9-11 except that in Control Runs 15-18 a portion of butadiene was added after the second styrene charges and before the second and final NBL charge, i.e., recipes of Control Runs 15-18 contained Step IIB (absent in recipes of Control Runs 9-11) employing 5-12 phm butadiene. The time for polymerizing the first butadiene charge in Step IIB was about 15 minutes. Temperature and pressure were about the same as listed for Step IIA (see recipes of Control Runs 9-11). It is expected that the following polymeric species before coupling were formed: S-S-B-S-B-Li and S-B-Li. 
     Control Run 19 was essentially the same as Control Runs 9-11 (Recipe in Example IV). 
     Monomer charges in polymerization Control Runs 9, 10, and Control Runs 15-19 inclusive, plus some key physical properties of formed resins are summarized in Table VII. NBL (n-butyllithium) charges (in phm) are designated L 1 , L 2 , L 3  ; styrene charges (in phm) are designated S 1 , S 2 , S 3  ; and butadiene charges (in phm) are designated B 1 , B 2 . 
     
                                           TABLE VII
__________________________________________________________________________
Run Charge
         15 16   17   9  10 18   19
__________________________________________________________________________
S.sub.1  26.4
            26.4 26.4 33 33 22   25.5
L.sub.1  0.04
            0.04 0.04 0.03
                         0.03
                            0.03 0.035
S.sub.2  26.6
            26.6 26.6 20 20 22   25.5
B.sub.1  12 5    5    0  0  8    0
L.sub.2  0.13
            0.13 0.13 0.13
                         0.13
                            0.13 0.145
S.sub.3  23 23   23   23 23 29   22
B.sub.2  12 19   19   24 24 19   27
Wt-% Butadiene
         24 24   24   24 24 27   27
Wt-% Styrene
         76 76   76   76 76 73   73
Flow Rate
         4.0
            12.5 3.6  -- -- 4.2  7.7
Haze (%) 15.4
            20.7 28.0 1.9
                         1.7
                            28.8 6.4
Dart Impact.sup.(1)
         --.sup.(2)
            &gt;81  &gt;81  -- -- &gt;81  &gt;80
Tensile Strength.sup.(3)
         2.42
            --   2.98 4.72
                         4.57
                            2.26 2.53
__________________________________________________________________________
 .sup.(1) determined in accordance with ASTM D 170975; given in inchlb.
 .sup.(2) a dash indicates not determined.
 .sup.(3) at yield; given in Kpsi
 
    
     Data in Table VII show that the control resins of Runs 15-18 inclusive employing two butadiene charges did not exhibit strength and impact advantages versus the control resins of Runs 9, 10, and 19 prepared with only one butadiene charge. In addition, the resins produced in Control Runs 15-18 inclusive possessed unacceptable high haze. 
     The control resin of Run 19 showed tensile similar to Runs 15, 17, 18; a somewhat better but still unsatisfactory haze as compared to Runs 15-19, though not as good as, Control Runs 9-10. None of these control copolymers were acceptable for clear copolymer usages requiring excellent mechanical properties. 
     EXAMPLE VII 
     Comparative resinous 76:24 weight ratio styrene:butadiene copolymers were employing a charge sequence of a single initiator charge, three incremental monovinylarene charges, and a single (final) conjugated diene charge (charge order L/S, S, S, B), followed by coupling. Anticipated species formed would be: S-B-L prior to coupling. Otherwise, the conditions employed were essentially similar to Recipe 1 above. 
     The so-prepared coupled resinous copolymers employing a single initiator charge do not exhibit any significant polymodality, despite multiple monomer additions. 
     These copolymers, while resinous, fairly transparent, with satisfactory flexural modulus and tensile, thus suitable for many purposes (importantly) shatter at only about 10-inch-lbs. Satisfactory craze resistant copolymers pass the test at about 60 inch-lbs and above, using the test shown in my Table VI footnote 3. 
     EXAMPLE VIII 
     The size and makeup of the polymeric species considered to be present in some of the above-described resinous, polymodal, butadiene-styrene copolymers are depicted below. 
     S 1 , S 2 , S 3 , each represents a block of polymonovinylarene formed after addition of and substantial completion of polymerization of a charge of monomeric monovinylarene. The subscripts indicate the order of formation. 
     B 1 , B 2 , B 3 , each represents a block of polyconjugated diene formed after addition of and substantial completion of polymerization of a charge of monomeric conjugated diene. The subscripts indicate the order of formation. 
     L represents the initiator residue on the end of a polymer-chain prior to any termination or coupling of the chain. Mode A, Inventive Resins 1, 2, and 3, prepared with three initiator charges, three styrene charges, and three butadiene charges, form an in situ mixture of the following three primary species before coupling since each NBL addition initiates a new polymer chain: 
     S 1  -B 1  -S 2  -B 2  -S 3  -B 3  -L 
     S 2  -B 2  -S 3  -B 3  -L 
     S 3  -B 3  -L. 
     Mode B, Inventive Resins 4, 5, and 6, prepared with two initiator charges, three butadiene charges, and three styrene charges, form an in situ the following two primary species before coupling: 
     S 1  -B 1  -S 2  -B 2  -S 3  -B 3  -L 
     S 3  -B 3  -L. 
     Mode C, Inventive Resins 7 and 8, prepared with three initiator charges, two butadiene charges, and three styrene charges, form the following three primary species before coupling: 
     S 1  -S 2  -B 1  -S 3  -B 2  -L 
     S 2  -B 1  -S 3  -B 2  -L 
     S 3  -B 2  -L. 
     Control Resins 9-14, prepared with two initiator charges, three styrene charges, and one butadiene charge, form the following two primary species before coupling: 
     S 1  -S 2  -S 3  -B-L 
     S 3  -B-L. 
     Control resins prepared with two initiator charges, three styrene charges, and two butadiene charges, form the following primary species before coupling: 
     S 1  -S 2  -B 1  -S 3  -B 2  -L 
     S 3  -B 2  -L. 
     Of course, in any sequence of solution polymerization stages, traces of initiator poisons, when present or introduced with feed streams, can cause termination of a few growing chains. For example, after the first stage, a small amount of S block polymer likely is present. 
     The sizes of the various S and B blocks, as well as B/S ratios and molecular weights of the different polymer species can be estimated. The method of calculation for these estimates is exemplified for Inventive Resin 1 (Recipe 1)(all calculations are based on assumption that no initiator poisons were present, and that initiation rates and propagation rates were equal). 
     
         ______________________________________
Initiator charges (NBL):
______________________________________
L.sub.1 (Steps IA/IB):
                0.025 phm = 0.39 mhm
L.sub.2 (Steps IIA/IIB):
                0.025 phm = 0.39 mhm
L.sub.3 (Steps III/IV):
                0.11  phm = 1.72 mhm
               NBL Total = 2.50 mhm
               (g-millimoles per 100 g monomers)
______________________________________
 
    
     Steps IA/IB 
     37 phm styrene and 3 phm butadiene polymerize to form (S 1  -B 1 ) x  -Li polymer chains where Li=lithium. 
     Steps IIA/IIB 
     A portion of added 16 phm styrene and of 3 phm butadiene polymerizes onto the existing (S 1  -B 1 ) x  -Li polymer chains; this portion is ##EQU1## 
     Thus 8.0 phm styrene and 1.5 phm butadiene form S 2  and B 2  blocks attached to S 1  -B 1  to form (S 1  -B 1 ) x  -(S 2  -B 2 ) y  -Li. The other portion, ##EQU2## of styrene and butadiene forms new polymer chains initiated with L 2 . Thus, 8 phm styrene and 1.5 phm butadiene form new polymer chains (S 2  -B 2 ) y  -Li. It is assumed that the propagation rate of both chains is the same. 
     Steps III/IV 
     The portion of 23 phm styrene and 18 phm butadiene polymerized onto (S 1  -B 1 ) x  -(S 2  -B 2 ) y  -Li chains is ##EQU3## Thus ##EQU4## and ##EQU5## are polymerized to form (S 1  -B 1 ) x  -(S 2  -B 2 ) y  -(S 3  -B 3 ) z  -Li chains. 
     The portion of styrene and butadiene polymerized onto (B 2  -S 2 ) y  -Li chains is ##EQU6## Thus 3.6 phm S 3  and 2.8 phm B 3  are polymerized to form (S 2  -B 2 ) y  -(S 3  -B 2 ) z  -Li chains. The portion of styrene and butadiene that forms newly initiated (S 3  -B 2 ) z  -Li polymer chains is ##EQU7## Thus ##EQU8## and ##EQU9## are polymerized to form (S 3  -B 3 ) z  -Li polymer chains. It is assumed that the propagation rate of each chain is the same. 
     The molecular weights (M n ) of the species before coupling can be estimated by dividing the number of phms of monomers in each chain (species) by the number of moles of Li associated with each chain: 
     
         ______________________________________
 .sup.37.0S.sub.1 --.sup.3.0B.sub.1 --.sup.8.0S.sub.2 --.sup.1.5B.sub.2
--.sup.3.6S.sub.3 --.sup.2.8B.sub.3
                ##STR1##
 .sup.8.0S.sub.2 --.sup.1.5B.sub.2 --.sup.3.6S.sub.3 --.sup.2.8B.sub.3
                ##STR2##
 .sup.15.8S.sub.3 --.sup.12.4B.sub.3
                ##STR3##
______________________________________
 
    
     The described calculations were also carried out for Inventive Resins 2-8 and for control Resins 12-14. Results are summarized in Table VIII: 
     
                       TABLE VIII
______________________________________
                        Bd:Styr.  M.sub.n Before
Resin Block Sequence, phm
                        Wt. Ratio Coupling
______________________________________
       ##STR4##         13:87     143,000
       ##STR5##         27:73      41,000
       ##STR6##         44:56      16,000
2
       ##STR7##         14:86     137,000
       ##STR8##         29:71      35,000
       ##STR9##         44:56      15,000
3
       ##STR10##        13:87     136,000
       ##STR11##        31:69      34,000
       ##STR12##        49:51      13,000
4
       ##STR13##        14:86     132,000
       ##STR14##        44:56      14,000
5
       ##STR15##        15:85     123,000
       ##STR16##        49:51      16,000
6
       ##STR17##        14:86     138,000
       ##STR18##        49:51      15,000
7
       ##STR19##        11:89     119,000
       ##STR20##        34:66      40,000
       ##STR21##        44:56      16,000
8
       ##STR22##        11:89     117,000
       ##STR23##        35:65      39,000
       ##STR24##        46:54      15,000
12-14
       ##STR25##         8:92     101,000- 120,000
       ##STR26##        51:49      18,000- 20,000
______________________________________
 
    
     The disclosure, including data, illustrate the value and effectiveness of my invention. 
     The resinous polymodal copolymer products of my invention are particularly useful as a blending component for general purpose polystyrene to improve greatly the scope of use of the polystyrene. 
     The Examples, the knowledge and background of the field of the invention, and the general principles of chemistry and of other applicable sciences, form the bases from which the broad descriptions of my invention including the ranges of conditions and the generic groups of operant components have been developed, and form the bases for my claims here appended.