Process for fiber treatment
United States Patent 1 Pattison Apr. 29, 1975 1 PROCESS FOR FIBER TREATMENT [75] lnventor: Victor A. Pattison, Tonawanda,  
 [73] Assignee: Hooker Chemicals 84 Plastics Corporation, Niagara Falls, NY.  
 [22] Filed: Jan. 12, 1973 [21] Appl. No.: 323,192  
 [52] US. Cl. 162/167; 260/295 AM; 260/295 CA [51] Int. Cl D2lh 3/12 [58] Field of Search..... 260/295 0A, 295 Q, 295 E. 260/295.5 C, 295 AM, 295 CA; 162/164,  
 [56] References Cited UNITED STATES PATENTS 2,518,266 8/1950 Baird et a1. 260/295 AM 2,518,267 8/1950 Baird et a1 260/295 AM Primary Examiner-Robert L. Lindsay, Jr.  
 Assistant ExaminerWi11iam F. Smith Attorney, Agent, or Firm-Peter F. Casella; John M. Petruncio [57] ABSTRACT Aqueous solutions of are used to improve wet-strength of fibrous materials.  
 7 Claims, No Drawings PROCESS FOR FIBER TREATMENT This invention relates to the treatment of fibrous materials. More particularly, this invention relates to the improvement of wet strength characteristics of paper and paper products. i  
  For many years, no commercially available wet strength resins were available which would function effectively at pHs much above about 5.5. As a consequence, many grades of paper and paper products made on the alkaline side for various reasons. including strength, softness, use of alkaline fillers or the like, could not be effectively wet-strengthened.  
  Attempts to allievate this and other problems have been made in the past. Recently, the wet-strengthening of paper and paper products by the use of polymeric reaction products of epichlorohydrin and polyamides derived from polyalkylene polyamines and saturated aliphatic dicarboxylic acids containing from 3 to carbon atoms has been prepared. Such resins have been proposed for use under pH conditions on the alkaline side in the production of alkaline papers, and in ap plication to fibers while the fibers are in dilute aqueous suspensions of the consistancy generally used in paper mills.  
  It is also known to produce paper having a measure of wet strength by mixing fibrous pulp with suspensions of polyvinyl alcohol, or with latex, and to produce paper from the thus formed mixture.  
  Unsaturated aliphatic dibasic acids, reacted with ammonia, a polyamine and epichlorohydrin have also been proposed for use in imparting wet strength to paper and paper products. However, universal acceptance of the wet-strengthening materials of the prior art has been less than total.  
  It is an object of the present invention to provide paper products having improved wet strength.  
  This and other objects and advantages of the present invention will become apparentfrom a reading of the description which follows and the appended claims.  
  Briefly stated, the wet strength characteristics of fibrous materials, such as paper and paper products, are improved by treating such materials with aqueous solutions of treating materials of the formula wherein R and R, are organic radicals, generally having from 1 to about 12 carbon atoms; is a number having a value of from about I to about 10, generally from about 1 to about 8, and preferably from about 2 to about 5; y is a number having a value of from zero to 3; z is a number having a value of from zero to 3; and X is halogen.  
  The fibers which may be treated in according with the process of the present invention include textile and paper fibers. and the process is particularly useful in treating paper pulp and paper products.  
  According to the process of the present invention, the fibrous materials are treated by applying thereto the materials hereinbefore defined as aqueous solutions, generally the solutions containing from about 0.1 to about 10 percent by weight treating material preferably from about 1 to about 5 percent by weight. The solutions may contain the treating materials in greater amounts; however, it has been found that subjecting the fibrous materials to treatment with aqueous solutions of treating material containing from about 1 to 5 percent by weight treating material, for a time sufficient to provide an addon of treating material from about 0.2 to about 2 percent by weight, based on the dry weight of the fibrous material treated, is sufficient.  
  The solution may be added to the material to be treated by any method known to the art. The solutions are particularly suited to the treatment of paper pulp. ln treatin pulp, the solution is added to the pulp slurry, with stirring, in amounts to obtain the desired addon, the pulp is sheeted out by conventional methods and dried.  
  The molecular weight of the treating material may vary from about 250 to about 2,500, of higher.  
  The treating materials used in the present process are prepared by:  
  a. N-methyl aniline, or a substituted N-methyl aniline, or mixtures thereof, is condensed with formaldehyde:  
  b. the product obtained from (a) is reacted with a carbonic dihalide to convert the N-methyl amino groups to carbamoyl halide groups;  
  e. the product of (b) is reated with pyridine N-oxide. substituted pyridine N-oxides, or suitable mixtures thereof to obtain the treating material.  
  Suitable carbonic dihalides are phosgene, carbonic dibromide, and the like. Preferably, phosgene is the carbonic dihalide utilized.  
  Suitable N-methyl anilines for use in formulating the resinous compositions of the present invention include N-methyl aniline; 3,5-dimethyl N-methyl aniline; 4- dodecyl N-methyl aniline; 4-phenyl N-methyl aniline; 4-naphthyl N-methyl aniline; 3-(2-chloro) propyl N- methyl aniline; 3,4,5-trimethyl N-methyl aniline, and the like, as well as mixtures thereof. The most preferred N-methyl aniline is the unsubstituted N-methyl anilines.  
  Suitable pyridine N-oxides for formulating the resinous compositions of the present invention include 3,5- dimethyl pyridine N-oxide; 3,5-dipropyl pyridine N- oxide; 3-methyl pyridine N-oxide; 4-naphthyl pyridine N-oxide; 4-phenyl pyridine N-oxide;3-hexyl pyridine N-oxide; 4-(3-choropropyl)pyridine N-oxide and the like, or mixtures thereof. The most preferred reactant is unsubstitutes pyridine N-oxide.  
  The formaldehyde employed may be obtained from such sources as aqueous solutions of formaldehyde, trioxane, paraformaldehyde, and the like. Preferably, the formaldehyde is used as an aqueous solution, about 37 percent by weight formaldehyde.  
  The reaction of the N-methyl aniline compound and formaldehyde is conducted by adding the formaldehyde on a continuous basis to the aniline compounds in a system acidified to a low pH by the use of a suitable mineral acid such as hydrochloric acid. the formaldehyde added in sufficient amounts to effect condensation of the anilines present. Following the addition of the formaldehyde, the reaction mixture is made alkaline by the addition thereto ofa suitable alkaline agent. as for example, aqueous sodium hydroxide, a solid product separating. The liquid phase is removed by decantation, and the residue heated to remove any remaining water. The pH of the reaction system. during the addition of formaldehyde. is generally maintained at 1 or less.  
  The temperature during the step (a) reaction is generally maintained at from about 100 to about 160C. preferably from about 130 to about 160C. with the time required to effect the condensation being on the order of from about 60 to about 90 minutes.  
  The reaction product of step (a) is then reacted with the selected carbonic dihalide, preferably phosgene. by adding a suitable solvent to the product. heating to temperatures sufficient to remove any water present, cooling to less than about 35C, and adding the carbonic dihalide continuously, in about stoichiometric amounts to react with the N-methyl amino groups. converting the groups to carbamoyl chloride groups.  
  Heat is applied to move the temperature gradually up to about 150C. evolving hydrochloric acid. The temperature is generally moved through a range of from about 35 to about 150C over a period of about 90 minutes. The solvent is removed by distillation, generally at about 120C under reduced pressures.  
  Suitable solvents include the halogenated hydrocarbons. such as chlorobenzene. dichlorobenzene and the like.  
  Generally the reaction is completed within a period of from about 90 to 120 minutes.  
  The reaction product from step (b) is then reacted with the selected pyridine N-oxide by adding the pyridine N-oxide in about stoichiometric amounts. based on the carbamoyl halide groups present. stirring and allowing the reaction mixture to stand for about 2-8 hours. maintaining the temperature at ambient temperatures; however. the reaction may be conducted at elevated temperatures. on the order of about 90C.  
 EXAMPLE 1 Approximately 4 moles N-methyl aniline is condensed with a stoichiometric amount of from aldehyde added as a 37 percent aqueous solution, at a pH of about 1 and a temperature of about 130C. The reaction product is added to dichlorobenzene solvent and heated to remove the water. Phosgene is added to the reaction system after cooling. and the temperature is gradually increased to about 150C. over a period of about 90 minutes. Following removal of the solvent 0.18 moles of the product and 0.18 moles of pyridine N-oxide are dissolved in 100 ml chloroform. The reaction mixture is stirred overnight. the solvent removed by evaporation. and 56 grams of a gray, water soluble product recovered having a molecular weight of about 100.  
  In the following examples, kraft pulp of 450 ml freeness. and 0.30 consistancy. is admixed with a percent aqueous dispersion of a resin prepared in accordance with-the procedure of Example 1. and the concentration is adjusted to the indicated level. After stirring for 30 minutes. hand sheets are prepared and cured for 30 minutes. at C and conditioned overnight at about 25C and 50 percent relative humidity. The results are set forth in the following table.  
 What is claimed is:  
  l. A process for rendering fibrous materials wetstrengthened which comprises treating said fibrous material with a wet-strengthening amount of an aqueous solution containing 0.1 to 10 percent of a treating material of the formula wherein R and R are alkyl or aryl organic radicals. having from 1 to 12 carbon atoms; is a number having a value of from 1 to 10; y is&#39;a number having a value of from zero to 3; z is a number having a value of from zero to 3; and X is halogen.  
  2. A process as defined by claim 1 wherein the treating material is present in an amount of from 1 to about 5 percent.  
 3. A process as defined by claim 2 wherein y and z are zero.  
 4. A process as defined by claim 3 wherein X is chlo- 5. A process as defined by claim 4 wherein the fibrous material treated is paper pulp.  
  6. A process as defined by claim 5 wherein the resin addon is from about 0.2 to 1.5 percent by weight.  
 7. The paper produced by the process as defined by claim 6.