Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/46—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/54—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen
  • D21H17/55—Polyamides; Polyaminoamides; Polyester-amides

Definitions

• This invention relates to paper and to the method of making the same. More particularly, it relates to paper having improved properties and to the method of makingthe 'same.
• the selected raw cellulosic material is subjected to cleansing. boiling, washing; bleaching and beating or reducing to pulp.
• the pulp comprises a dilute suspension of beaten cellulosic fibers, and paper is formed therefrom by draining most of the water therefrom and drying the resultant wet mat of entangled fibers until essentially water free.
• Paper made by the aforementioned process is known in the art as water-leaf paper. It quite readily absorbs water, possesses little or no strength when water wet, and has other properties which materially limit its use.
• various materials are commonly incorporated with the cellulose fibers either before or after the web or sheet is formed to produce or improve certain desirable properties.
• rosin or animal glue have been employed to impart water resistance, clay to improve printing properties, plasticizers toenhance softness, and starch to improve the dry strength of the paper.
• Such papers do not have a high wet strength, which is highly desirable for a number of various uses.
• Paper has also been coated with various water resisting compositions. Due to the coating, the water absorbency of the paper has been reduced to a minimum and the product has a difierent appearance, feel and hand" from uncoated papers.
• An object of this invention is to provide a new 8 Claims. (01. 117-1 55) and improved paper and method of preparing the same.
• Another object of this invention is to provide a paper having improved tensile strength and bursting strength both in the dry and in the water wet state.
• a further object of this invention is to provide a. paper wherein the resistanceof the paper to linting and to rubbing r abrasion, either in the dry or water wet state, is improved.
• a specific object of this invention is to provide a highly absorptive paper having improved tensile strength both in the dry and water wet condition.
• the product of this invention does not materially differ in appearance and feelfrom the untreated paper and is characterized by a high water absorbency and high tensile strength. As will hereafter appear, the tensile strength, especially in the water wet state, has been improved to such a degree over the untreated paper that the results are truly amazing.
• the synthetic linear polyamide and formaldehyde are dissolved in an appropriate solvent to which the acid is added and water-leaf paper impregnated with such solution. After impregnation, the paper is dried at an elevated temperature. The dried paper is then washed in water until acid free and then redried.
• the bath was prepared by first dissolving the polymerized omega amino caproic acid in the formic acid and thereafter adding the formaldehyde.
• the excess liquid was removed by blotting between blotting paper.
• the paper was then dried for 30 seconds on the surface of a glass cylinder containing steam at 100 C.
• the paper was then washed in water until acid free and then redried on the surface of the glass cylinder for 30 seconds.
• the treated paper contained 1.4% by weight of polymerized omega amino caproic acid.
• the paper resulting from this process did not materially differ in appearance and feel from the untreated paper but was characterized by high tensile strength and high water absorptivity.
• the treated paper contained 0.95% of synthetic linear polyamide.
• the paper resulting from this example was highly water absorptive and had a relatively high wet tensile strength as well as a relatively high dry tensile strength.
• the rate of climb of water is the test used to determine the water absorption.
• the test consists of vertically suspending and immersing 1" of a test strip of paper 1" wide in distilled water at a controlledtemperature of 75 F. The water then penetrates up the paper by capillary attraction. The measurement consists in determining the time, in seconds, for the water to climb l".
• Example I Water-leaf paper of the type referred to in Example I was dipped into the following bath and treated as set forth in Example I:
• the self-polymerized omega amino caproic acid existed essentially as small colloidally dispersed particles.
• the bath was prepared by dissolving the self-polymerized omega amino caproic acid in the alcohol and 19 parts of water and the resulting solution added to a mixture of 60 parts of water and the formaldehyde whereby the selfpolymerized omega amino caproic acid was precipitated.
• the paper After the removal of the paper from the bath, it was pressed between sheets of blotter paper to remove excess liquid. The paper was then partially dried by placing on a drier at 100 C. for approximately 15 seconds. The paper was then acidified by immersion in a mixture containing 50 parts of 95% formic acid and 50 parts of water. The excess acid was removed by blotting and the paper was dried for 30 seconds at C. Thereafter, it was washed until essentially acid free and redried at 100 C.
• Example IV The process as shown by Example IV can be successfully carried out by first incorporating the synthetic linear polyamide and the formaldehyde in the paper and thereafter in another operation incorporating the requisite quantity of acid.
• the three ingredients are simultaneously incorporated into the paper by one operation by impregnation with a liquid composition containing them.
• the acid (formic) is a solvent for the synthetic linear polyamide
• it, the acid can constitute the liquid vehicle of the composition.
• a solvent for the polyamide which is preferably also miscible with the formaldehyde and acid (or, in the event the acid is a solid, the latter will be soluble in the solvent), is utilized.
• base moi designates the molecular weight of the monomer unit is distinguished from the molecular weight of the long chain polymer (polyamide) molecules.
• the relative proportions of the synthetic linear polyamide and the formaldehyde, or its equivalent are not limited to those set forth in the specific examples.
• the preferred relative proportions of the ill polyamide and formaldehyde, or its equivalent, with water-leaf paper is in the ratio of ,1 base molor polyamide to from 1 to 15 mols of formaldehyde, since such proportions produce the most desirable results.
• the impregnating bath also contains the acid, the latter is present in an amount of from to"7% by'weight ofthebath.
• the temperature to which the impregnated paper is subjected is not critical. Good improvement in wet and dry tensile strength with minimum reduction in water absorptiveness has been obtained by air drying the impregnated paper overnight at room temperature (25 C.). Drying the impregnated paper for 60 seconds at 118 C. (a representative temperature for paper machine driers) also produced verygood improvement. Thus, in general, the improvements obtained by this invention are attained irrespective of the mode or manner of drying. The selectedtemperature and time of drying should be such that the degradation of the cellulose fibers does not become substantial. I
• the improvement in physical characteristics'of (dried) water-leaf paper treated by the instant invention is obtained in conjunction with a minimum reduction in the absorptivity of the untreated paper.
• the improvements in the physical properties are obtained through the conjoint use of the synthetic linear polyamide and the formaldehyde or derivatives thereof.
• the improvements obtained from the conjoint use of the" synthetic linear polyamidev and the formaldehyde or derivative thereof are not the additive improvements of the properties of these components, but, as hereinbefore described, unexpected and surprising improvements are obtained. That the improvements are not merely the summation of the .prop erties of the synthetic linear polyamide and formaldehyde are shown by the following table wherein the physical properties of water-leaf paper similarly treated with the respective compositions set forth are given:
• compositions of baths I, II and III of th above Table II are as follows:
• The" desired properties are obtained when the treated paper contains from 1.2% to 1.5% by weight of the synthetic linear polyamide. However, decided improvements are obtained when the treated paper contains the synthetic linear poiyamide in an amount as low as 0.5% or as high as,5.0% by weight of the paper.
• the paper was impregnated with a bath containing the synthetic linear poiyamide and formaldehyde or its equivalent and the impregnated paper dried in the presence of an acid, the latter being either a component of the impregnating bath or applied to the impregnated paper
• the invention is not restricted to such procedures and such specific impregnating baths.
• An impregnating bath obtained by dissolving in an appropriate solvent the product separated from the reaction mixture resulting from heating a solution of a synthetic I linear polyamide of the type previously described in an appropriate solvent with formaldehyde, or its equivalent, in the presence of an acid of the type-hereinbefore described can also be used.
• a solution of a synthetic linear poiyamide of the type hereinbefore described, and preferably self-polymerized amino caproic acid in ethyl alcohol is heated with formaldehyde under acidic conditions to 60 C. to 70 C. for approximately to 1 hour, the proportions of the ingredients being as hereinbeiore described. Thereafter, the reaction product is precipitated into a non-solvent, such as acetone. This precipitate, which is in the finely divided state, is washed with water and, after dissolving in ethyl alcohol, constitutes the impregnating bath.
• a non-solvent such as acetone
• Paper and particularly water-leaf paper, is impregnated with such bath and, after the excess solution is removed, the impregnated paper is dried under acidic conditions for approximately 30 seconds on a glass cylinder containing steam at 100 C.
• the acid may be incorporated in the impregnating bath or added to the impregnated paper in a manner similar to that previously described.
• the invention is not restricted to any precise mode of incorporating the desired components in the paper.
• any method for incorporating the ingredients substantially homogeneously in the paper such as, for example, impregnation, dipping, flowing, spraying, etc., can be used.
• the instant invention provides a highly absorbent paper which is characterized not only by a high dry tensile strength but also by a remarkably high wet tensile strength.
• the treated paper of this invention is admirably suited for use as paper toweling, filter paper, label paper, handkerchiefs, napkins, diapers, etc. and, in general, for any purpose wherein a high wet strength is prerequisite.
• the invention is admirably suitable for use in the treatment of (dried) water-leaf paper.
• the invention is not restricted to such paper. Since it can be applied to various other types of papers, the improvement imparted to such papers depends on the nature of the paper treated.
• a method of preparing absorptive paper of high wet strength from water-leaf paper without materially changing the appearance and feel thereof which comprises impregnating waterieaf paper with a solution comprising 1 base moi of self-polymerized omega amino caproic acid and 1 to 28 mols of formaldehyde dissolved in ethyl alcohol, said solution containing an acid catalyst, said self-polymerized omega amino caproic acid being present in said solution in an amount of from 1% to 1.25% by weight, drying said paper, removing said acid catalyst, and redrying the resulting product whereby said paper is substantially uniformly impregnated throughout with from 1.2% to 1.5% of said polymerized omega amino caproic acid.
• the method of preparing a highly absorptive paper of improved tensile strength both in dry and water wet condition which comprises impregnating paper with a formic acid solution containing formaldehyde and about 1 per cent of self-polymerized omega amino caproic acid, drying the impregnated paper, washing the dried paper with water and redrying the paper whereby said paper is substantially uniformly impregnated throughout with from 0.5% to 5.0% of said polymerized omega amino caproic acid.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Paper (AREA)

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Publications (1)

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Family Applications (1)

Country Status (3)

Cited By (5)

Citations (3)

• 1945
  • 1945-10-27 US US625107A patent/US2540352A/en not_active Expired - Lifetime
• 1946
  • 1946-08-23 GB GB25187/46A patent/GB620509A/en not_active Expired
  • 1946-10-10 FR FR934425D patent/FR934425A/fr not_active Expired

Patent Citations (3)

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