Coating composition comprising polyisocyanate, hydroxyl compound, and tar
United States Patent 1 Ishihara et a1.  
 1 Apr. 29, 1975 COATING COMPOSITION COMPRISING POLYISOCYANATE, HYIIROXYL COMPOUND, AND TAR [75] lnventors: Takamasa Ishihara; Hirohumi Tuka; Shinichi Hasegawa, all of Osaka, Japan [73] Assignee: Sumitomo Chemical Company,  
 I Limited, Osaka, Japan [22] Filed: Oct; 4, 1972 21 Appl. 198.; 294,948  
 [30] Foreign Application Priority Data Oct. 5. 1971 Japan 46-78533 [52] US. Cl. 260/28 [51] Int. Cl C08g 51/52 [58] Field of Search 260/28 [56] References Cited UNlTED STATES PATENTS 3.092.594 6/1963 Heiss 260/28 3.179.610 4/1965 Wood 260/28 3.182.032 5/1965 Charlton.... 260/28 3.372.083 3/1968 Evans 260/28 3.412.050 11/1968 Elkin 260/28 3.468.822 9/1969 Wismcr 260/28 3.615.801 10/1971 Marklow 260/28 Primary Examiner-Allan Lieberman Assistant Examiner-P. R. Michl Attorney, Agent, or Firm-Stewart and Kolasch 7 Claims, No Drawings COATING COMPOSITION COMPRISING POLYISOCYANATE, HYDROXYL COMPOUND, AND TAR The present invention relates to a coating composition, particularly to an improvement in a coating composition of tar-epoxy resin or tar-polyurethane resin.  
  The coating composition of tar-epoxy resin or tarpolyurethane resin has been widely used as a water repellent, a corrosion inhibitor or the like for building materials, iron or non-ferrous vessels, instruments, apparatuses, steel pipes, sea side buildings and so on, because of its good chemical resistance, flexibility, adhesiveness and abrasion resistance with low costs. Such coating composition, however, contains as the tar component in the binder, coal tar, coal tar pitch or petroleum asphalt, usually in an amount of 40 to 75 by a weight, and is defective in being not colorable due to the black color of the tar component, having a low hardening rate because of the non-reactivity of tar component to&#39;the resin component and requiringa troublesome handling so as to avoid an unfavorable influence caused by harmful nitrogen-containing compounds and the carcinogenic benzpyrene&#39; contained in the tar component. Further, the hardened material resulting from the coating composition exhibits disadvantageously a heat plasticization.  
  In order to overcome the said defects in the conventional coating composition containing coal tar, coal tar pitch or petroleum asphalt as the tar component, various investigations have been made. As a result, it has been found that the use of cresol tar as the tar component can provide a coating compositionof tar-epoxy resin or tar-polyurethane resin having various advantageous properties.&#39;as compared with the conventional one.  
  The coating composition of the present invention comprises an extender, a solvent and a binder containing an epoxy resin, a hardener and a tar, or polyisocyanate, a hydroxyl compound and a tar, the tar being cresol tar, i.e. the distillation residue having a boiling point of not lower than 200C, said residue being produced during the preparation of cresols .u sing cymene.  
  In the coating composition of the invention, the extender and the solvent may be the ones as heretofore used in the conventional coating composition of tarepoxy resin or tar-polyurethane resin.  
  The binder in the coating composition of the invention is characteristic in containing cresol tar as the tar component.  
 The cresol tar is the distillation residue obtained in&#34; the preparation of cresols fromcymene according to the so-called cymene method which comprises oxidizing cymene to cymene hydroperoxide and decomposing the latter to give a reaction mixture containing acetone and cresol. Removal of the substances having low boiling points such as acetone, unreacted cymene and dimethylstyrene and then cresol from the said reaction mixture by rectification leaves the distillation residue which is utilizable as the tar component in the coating composition of the invention. The distillation residue is a mixture of the substances&#39;having high boiling points such as 200C or higher, preferably having boiling points not lower than 260C at 760 mml-lg, among which those having an active group(s) such as phenolic hydroxyl, alcoholic hydroxyl, acetyl and aldehyde groups may be contained. The fraction collected within 0 procedure asin the conventional coating composition a range between 200C (preferably 260C) and 350C is white to light color and the fraction collected at 350C or higher (practically collected at a lower temperature under a reduced pressure) is pale yellow to pale brown, and therefore they can be used for a colorable coating composition. The residual fraction, i.e. the pitch-wise residue, may be used for a black coating composition by dissolving it into an organic solvent such as an aromatic solvent (e.g. benzene, toluene, xylene) or anthracene oil obtained from coal tar.  
  The epoxy resin may be the one as used in the conventional coating composition of tar-epoxy resin and soluble in the cresol tar. Examples of the hardener are amines, amine adducts and polyamides, which are usually employed for epoxy resins.  
 The mixing ratio of the epoxy resin to the hardener may be determined appropriately in consideration of the hardening ability and the pot-life.  
 The cresol tar can be mixed according to the same of tar-epoxy-resin, and the amount is favorably from 30 to by weight based on the weight of the binder. When desired; the binder may contain suitable pigments, fillers, organic solvents and the like in addition to the essential materials, i.e. the epoxy resin, the hardener and the cresol tar.  
  Examples of the polyisocyanate are tolylenediisocyanate, l,5-naphthylenediisocyanate, 4,4 diphenylmethanediisocyanate, hexamethylenediisocyanate, xylylenediisocyanate and polymethylenepolyphenylenediisocyanate. The hydroxyl compound includes, for example. polyesters, caster oil. and tall oil, and the most preferable compounds are polyalkylene oxides disclosed in Kobunshi Kako. 19, 734 1970).  
  The hydroxyl compound is used in a amount of 0.8 to 2.0 equivalents, preferably 1 equivalent. to the isocyanate group (-NCO) contained in the polyisocyanate. and the cresol tar is used in an amount of 30 to 70 7: by weight based on the combined weight of the polyisocyanate and the hydroxyl compound. The binder may further contain fillers, organic solvents, organic tin compounds, anti-oxidants, ultraviolet ray absorbers and the like, when desired.  
  The coating composition of the present invention may be coated on various materials such as building materials, iron or non-ferrous vessels, instruments, apparatuses, steel pipes and sea side buildings according to anyconventional procedure such as brush coating or spray coating so as to make them water-proof and corrosion inhibited.  
 Practical and presently preferred embodiments of the invention are illustratively shown in the following Examples wherein parts are by weight.  
 Example 1 A. A mixture of an epoxy resin (Epikote No. l00l produced by Shell Co.) (40 parts), talc (produced by Matsumura Co.) (40 parts), xylene (106 parts) and sec.-butanol (9.0 parts) was passed three times through a 3 roll mill to disperse the tale well into the mixture. The resulting mixture was admixed with a mixture of a polyamide hardener (Varsamide produced by Daiichi Kogyo Seiyaku Co.) 16.0 parts) and cresol tar (transparent pale yellow liquid: B.P., 260 to 350C; specific gravity, 1.019) (67.2 parts). The resultant coating composition was coated on a plate of mild steel having an area of 7.5 cm X 15 cm and a thickness of 0.8 mm to make a 200 1. thickness of the coated layer.  
  B. As in Example 1 (A) but using cresol tar (brown liquid; B.P., 260C or higher) as a tar component. the coating composition was prepared and coated on a plate of mild steel.  
  For reference, a coating composition was prepared as in Example 1 (A) but using coal tar (Tarkron No. 180&#34; produced by Yoshida Seiyu Co. Ltd.) as the tar component and coated on a plate of mild steel.  
  The above obtained coated plates were allowed to stand for 7 days and then subjected to various tests. The results are shown in Table 1.  
 Table 1 Example I (A) l (B) Reference Pot-life at 24 24 24 25C (hr) Time required for fingering dryness 6 6 l at 25C (hr) Time required for 36 36 48 hardening at 20C (hr) Cross-cut 100/100 IOU/100 I00] I00 Chemical resistance Acid resistance No change No change Swollen on l0 7! H 80 sol.) for l for 1 th day month month Alkali resistance do. do. Swollen on l0 71 NaOH sol.) th day Water repellancy No change No change No change for l for l for l month month month Salt water spray No change No change Peeled off resistance by rust (300 hrs) Hardness of the HB HB H m Color of the film Pale Brown Black Yellow Example 2 Medium fractions of cresol tar collected at 260? to 350C (transparent pale yellow liquid; specific gravity (d /4); 1.019) (40 parts). titanium .white (40 parts), a polyol (Desmophene 7200 OH No. 42&#34; produced by Bayer A.G.; viscosity; 670 cps/25C) (35 parts) and 4,- 4-diphenylmethanediisocyanate (20 parts) were mixed uniformly. The resulting coating composition was coated on a plate of mild steel having an area of 7.5 cm X 15 cm and a thickness of 0.8 mm to make a 200 ,u. thickness of the coated layer.  
  For reference, a coating composition was prepared as above but using white tar (Tarkron White No. 30&#34; produced by Yoshida Seiyu Co. Ltd.) as the tar component and coated on a plate of mild steel.  
  The above obtained coated plates were allowed to stand for 7 days and then subjected to various tests. The results are shown in Table 2.  
 Table 2-Continued Tar C resol tar White tar Hardness H8 H8 Cross cut test 25/25 25/25 Erichsen test 6 mm or higher 2 mm Chemical resistance Acid resistance Good Good Alkali resistance Good Good (5 &#39;71 NaOH) Color of the film The first day Pale yellowish Pale yellowish white brown After 2 days Pale yellow Dark yellowish light exposure brown Example 3 Cresol tar (brown liquid; specific gravity (d 25/4), 1.047; B.P., 230C or higher; Engler viscosity (/20), 3) (35 parts), a polyol (Desmophene 7200 OH No. 42&#34; produced by Bayer A.G.; viscosity. 670 cps/25C) (25 parts), talc (30 parts) and tolylenediisocyanate 15 parts) were mixed uniformly. The resulting coating composition was coated on a plate of mild steel having an area of 7.5 cm X 15 cm and a thickness of 0.8 mm to make a 200 p. thickness of the coated layer.  
  For reference, a coating composition was prepared as above but using coal tar (refined tar produced by Osaka Gas Co. Ltd.) as the tar component and coated on a plate of mild steel.  
  The above obtained coated plates were allowed to stand for 7 days and then subjected to various tests. The results are shown in Table 3.  
 What is claimed is:  
  l. A coating composition which comprises a binder containing l a polyisocyanate compound selected from the group consisting of tolylenediisocyanate. 1.5-  
 napthylenediisocyanate, 4.4 diphenylmethanediisocyanate hexamethylenediisocyanate, xylyenediisocyanate and polymethylenepolyphenylenediisocyanate and a hydroxyl compound and (2) a tar. the tar being a distillation residue having a boiling point of about 200 to 350C, said residue being produced during the preparation of cresols from cymen&#39;e, the amount of hydroxyl compound employed being 0.8 to 2.0 equivalents with respect to the number of isocyanate groups contained in said polyisocyanate compound.  
  2. The composition according to claim 1, wherein the tar is used in an amount of 30 to 7O 7: by weight based on the combined amount of the polyisocyanate and the hydroxyl compound.  
  3. The coating composition of claim 1, wherein the distillation residue has a boiling point not less than about 260C.  
  4. The coating composition of claim 1, wherein the hydroxyl compound is selected from the group consisting of polyesters, castor oil, tall oil and a polyalkylene sorbers.