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
  • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/35—Polyalkenes, e.g. polystyrene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F20/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride, ester, amide, imide or nitrile thereof
  • C08F20/62—Monocarboxylic acids having ten or more carbon atoms; Derivatives thereof
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F22/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals each having only one carbon-to-carbon double bond, and at least one being terminated by a carboxyl radical and containing at least one other carboxyl radical in the molecule; Salts, anhydrides, esters, amides, imides or nitriles thereof
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F236/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds
  • C08F236/02—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds
  • C08F236/04—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F36/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds
  • C08F36/02—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds
  • C08F36/04—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
  • C09J7/205—Adhesives in the form of films or foils characterised by their carriers characterised by the backing impregnating composition
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
  • C09J7/00—Adhesives in the form of films or foils
  • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
  • C09J7/21—Paper; Textile fabrics
• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
  • D06M15/693—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with natural or synthetic rubber, or derivatives thereof

Definitions

• the present invention relates to latex compositions of certain carboxylated conjugated diolefin copolymers exhibiting enhanced adhesiveness and fiber bonding properties, and to improved unified non-woven fibrous articles, such as fibrous webs or mats, internally bonded with these particular diene-containing copolymers. More particularly, the invention relates to latices of copolymers of dienes and polycarboxylic acids and to flexible non-woven fibrous sheeting, such as paper, non-woven fabrics, and the like, containing these copolymers which exhibit strong affinity for the fibers and impart a high internal bond strength to the unified mass.
• the invention involves impregnated paper backing sheets suitable for fabrication into pressure-sensitive adhesive tapes, and the tapes so produced, such sheets being characterized by an unexpected development of unusually high internal bond strength and a resultant high resistance to delamination of the paper backing, in combination with other advantageous properties.
• non-woven fibrous material means a mat, web, or sheet of fibers laid down by mechanical, pneumatic, electrical or vacuum means, or otherwise deposited.
• the typically open, highly porous and unbonded structure of webs or mats made of such fibrous materials inherently has little or no internal bond and hence little or no resistance to delamination, splitting and tearing.
• non-woven fibrous articles of highly improved internal bond strength are obtainable by unifying the fibrous materials with polycarboxylic acid-containing diene polymers.
• Diene copolymers particularly suitable for use in the unifying compositions of theinvention are polycarboxylic acid-containing copolymers prepared from monomeric material at least predominantly comprising one or more aliphatic conjugated dienes and one or more non-carboxylic ethylenically unsaturated monomers copolymerizable with the diene, the polycarboxylic acid content being derived from the non-carboxylic monomer, or supplied by a separate substance.
• the copolymers of the invention may be formed by direct copolymerization of a monomer mixture of a diene, a non-carboxylic monomer and a polycarboxylic acid or anhydride, or by other methods, such as by copolymerization of a diene and a non- .carboxylic monomer from which the acid groups may be derived after polymerization.
• fethylenically unsaturated monomers includes copolymerizable monoolefinic monomers, and is to be construed as excluding conjugated dienes, but may include other polyolefinic monomers, e.g.
• polycarboxylic acid content of the copolymer is obtained by copolymerization of the diene with a copolymerizable ester or other hydrolyzable compound of a polyolefinic polycarboxylic acid followed by hydrolysis to form the acid groups in the copolymer, as described below.
• non-carboxylic means the monomer is devoid of carboxyl (COOH) groups and salts formed by such groups.
• Such polycarboxylic acid polymers may be advantageously obtained by copolymerization in acid aqueous dispersion of a minor portion of at least one copolymerizable olefinically unsaturated polycarboxylic acid with a major portion of one or more aliphatic conjugated dienes and one or more copolymerizable non-carboxylic monoolefinic monomers.
• monoolefinic means monoethylenically unsaturated
• non-carboxylic has the same meaning as set forth above.
• the non carboxylic monomer appears to facilitate direct copolymerization of the acid, and the proportions of diene and non-carboxylic monomer may widely vary, as set forth below.
• the unexpectedly high internal bond strength is advantageously obtainable with a relatively small content of polycarboxylic acid in the diene copolymer and effective amounts may be as low as about 0.005, expressed as carboxy (COOH) equivalents per hundred grams of copolymer.
• the polycarboxylic acid content in the copolymer may be much higher, such as that obtainable in the acidic aqueous copolymerization of the copolymerizable olefinically unsaturated polycarboxylic acid with a major portion of the diene and monoolefinic monomer constituents, or such as are obtainable through introduction of the polycarboxylic acid into the copolymer by other suitable methods above-mentioned and hereinafter described.
• the polycarboxylic acid-containing copolymers permit the development of unique combinations of properties with the high internal bond strength, which are not obtainable with the ordinary synthetic latices when used as saturants, among which may be mentioned, the retention of high internal bond strength with pigmentation, high elongation with retention of internal bond and tensile strengths, resistance to oils and solvents, and non-discoloration on exposure to ultraviolet light, and in tape applications the avoidance of a tie or primer coat for securing the pressure-sensitive adhesive to the bonded fibrous backing.
• the fibrous masses may have a suitable copolymer content imparted by impregnation, such as dip saturation of preformed webs or sheets, or by beater addition of an aqueous dispersion of copolymer directly to the fibers prior to formation of any web or'sheeting.
• the copolymer is deposited from aqueous dispersions onto the fibers and within the interstices of the open, porous web or sheeting.
• the copolymer latices of the invention is that the pH is not confined to a narrow range.
• the dispersions for impregnation may be acid, that is, they may be used after acid polymerization Without neutralization, or if desired, they may be neutralized prior to impregnation of the fibrous articles while still retaining the enhanced adhesiveness and fiber bonding properties.
• the copolymerization of the diene and the comonomer may be in alkaline aqueous medium.
• the material is freed of excess saturant, usually by passing through squeeze rolls or the like, and is then subjected to a drying operation.
• the polymer content on a dry solids basis may be from about 30 percent to 60 percent by weight of the dry unified web or sheeting.
• the internal bond strength varies with polymer content. This corresponds approximately to 40 to 150 percent saturation or pickup.
• the polycarboxylic acid-containing copolymers are preferably teror multi-polymers formed by the acid copolymerization of monomeric material containing a major portion of one or more aliphatic conjugated dienes, preferably 1,3 conjugated dienes having 4 to 10 carbon atoms, such as butadiene 1,3, and one or more noncarboxylic copolymerizable monoolefinic monomers, and a minor portion of at least one copolymerizable olefinically unsaturated polycarboxylic acid.
• suitable acids are characterized by possessing one or more olefinic carbon-to-carbon double bonds and two or more carboxyl groups, in which at least one of the olefinic carbon-to-carbon double bonds is activated, as is understood in the polymerization art, to render the acid copolymerizable with the butadiene and the noncarboxylic monoolefinic monomer.
• R is preferably hydrogen or carboxyl, but may be carboxylic ester, alkyl or alkenyl
• Y is hydrogen, carboxyl, halogen, cyano, sulfo, alkyl, aryl, thienyl or furyl
• Z is a methylene or a substituted methylene group, or an al-lyl, arylene, thienylene or furylene divalent radical
• x is zero or any whole number, suitably not exceeding 3 and in which at least one of the groups R and Y is carboxyl, or Z is carboxyl-containing.
• such olefinically unsaturated polycarboxylic acids include fumaric, maleic, citraconic, mesaconic, itaconic, aconitic, ethyl maleic acid, methyl itaconic, muconic, hydromuconic, glutaconic; 3-carboxy-penta-. diene-(2,4)-oic-1, beta-(p-carboxyphenyl) acrylic, 2,4- pentadiendioic-1,3 acid, the dimer and trimer of methacrylic acid and other monoolefinic and polyolefinic polycarboxylic acids.
• polycarboxylic acid groups may be utilized.
• One such method is the copolymerization with the aliphatic conjugated diene, of copolymerizable partial or full esters of the olefinically unsaturated polycarboxylic acids, followed by hydrolysis of a part or all of the ester groups to obtain the polycarboxylic acid groups in the polymer chain. This may be accomplished, for example, by hydrolysis in alkaline medium under suitable temperature and pressure conditions. Acidification of the resulting salt produces the free acid.
• the copolymers may be prepared from monomeric materials containing hydrolyzable groups other than the carboxylic ester group, such as nitriles, amides and acid chlorides to yield the free polycarboxylic acid groups on hydrolysis.
• the copolymerization system may consist simply of the diene and the ester of the polycarboxylic acid where the ester replaces completely both the polycarboxylic acid and the monoolefinic monomer, or the .ester may merely replace the acid in whole or in part,
• the substituted dienes such as Z-chloro butadiene-1,3; 1- or 2-cyano-butadiene-1,3; the straight chain conjugated pentadienes such as piperylene; the-straight and branched chain conjugated hexadienes and others.
• dienes containing more than 10 carbon atoms polymerize very slowly, if at all, in present polymerization v systems, and it is therefore preferred to employ a diene having 10 carbon atoms or less, while dienes having from 4 to 6 carbon atoms have particularly advantageous reaction rates and polymerization characteristics and are much preferred.
• the non-carboxylic monoolefinic monomer which together With the aliphatic conjugated diene constitutes a major portion of the monomeric material for directly preparing the copolymers useful in the invention may be any such monomer, which is copolymerizable with the diene, as is well known in the art, and indicated by typical monomers set forth below.
• the noncarboxylic monoolefinic monomer is characterized as one which contains an activated carbon-to-carbon double bond, that is, a monomer containing an olefinic double bond which readily functions in an addition polymerization reaction because of the olefinic double bond being present in the monomer molecule either in the alpha-beta position
• an activated carbon-to-carbon double bond that is, a monomer containing an olefinic double bond which readily functions in an addition polymerization reaction because of the olefinic double bond being present in the monomer molecule either in the alpha-beta position
• a strongly polar or functional group such as nitrile, carboxylic ester, halogen, keto, amide and other such groups well known in the art as activatinggroups, or because it is adjacent to a terminal methylene group, i.e.
• aliphatic unsaturated nitriles such as the low molecular weight nitriles, acrylonitrile, alpha chloro acrylonitrile, methacrylonitrile, ethacrylonitrile, the low molecular weight alcohol esters of acrylic and substituted acrylic acids, such as methyl methacrylate, methyl acrylate, methyl ethacrylate, butyl methacrylate, isobutyl dichloroacrylate and other acrylic esters of alcohols, preferably having from 1 to 6 carbon atoms; styrenes, such as styrene itself, halo, cyano, alkyl, aryl, and other substituted styrenes, for example, vinyl toluene, alpha methyl styrene, alpha chloro sty
• copolymerizable monoolefinic monomers selected from the group consisting of nitriles, styrenes and lower molecular weight alcohol esters of acrylic and alpha-substituted acrylic acids.
• the copolymerizable monoolefinic monomer When the copolymer is produced by copolymerization of the polycarboxylic acid, the copolymerizable monoolefinic monomer apparently facilitates the introduction of the polycarboxylic acid groups into the copolymer, as indicated by the developed internal bond in the unified fibrous articles, and present analytical methods for the determination of carboxyl content in the polymer chain, such as alkalimetric titration of the copolymer solution with alcoholic KOH to a phenolphthalein end point.
• the monomeric material advantageously may vary within very wide limits in regard to amounts of diene and non-carboxylic monoolefinic compound.
• the invention provides for the preparation of the polycarboxylic acid-containing copolymers from monomeric mixtures of from about 10 to 75 percent by weight of the total monomer charge of one or more of the monoolefinic monomers and from about to 90 percent by weight of the conjugated diene, the combined weight of these two monomeric materials being a major portion of the total monomeric mixture.
• the polycarboxylic acid constitutes a part of the monomer charge it may be present in amounts from as low as about 0.5 percent up to any minor portion, i.e.
• the polybasic acid charge in the direct emulsion copolymerization of the polycarboxylic acid-containing copolymer economically constitutes from about 1 to 20 percent by weight of the monomer charge, since it has been found that the major advantages of the invention can be achieved with such amounts. It is a distinct advantage of the invention that the adhesiveness and fiber-bonding property of the copolymers to provide excellent internal bond strengths are obtainable with relatively small quantities of polybasic acid, such as 1 to 5 percent.
• the copolymerization of the polycarboxylic acid-containing copolymers is advantageously effected by emulsification of the monomers in acid aqueous medium using emulsifiers stable therein.
• Suitable emulsifiers include the ethers and esters of polyglycols with aliphatic acids having from 10 to 20 carbon atoms; alkyl sulfonates or sulfates and alkaryl sulfonates where the alkyl group contains from 10 to 20 carbon atoms, alkaryl polyether sulfates or sulfated monoglycerides and similar emulsifiers that will occur to those skilled in the art.
• a particularly effective type of emulsifier has been found to be the amine salts of alkaryl sulfonates.
• the polymerization system may also include small amounts of stabilizers known to the art.
• the polymerization reaction may be promoted by the addition of free-radical yielding initiators such as the alkali persulfates, percarbonates, perborates and the like, organic peracids, such as benzoyl peroxide, acetyl peroxide, and the like, alkyl peroxides such as di-t-butyl peroxide and organic hydroperoxides, such as diisopropylbenzene hydroperoxide.
• free-radical yielding initiators such as the alkali persulfates, percarbonates, perborates and the like, organic peracids, such as benzoyl peroxide, acetyl peroxide, and the like, alkyl peroxides such as di-t-butyl peroxide and organic hydroper
• the polymerization mass may also contain small amounts of the sulfhydryl-group-containing compounds termed modifiers in the synthetic rubber industry, such as alkyl mercaptans containing from about 10 to 22 carbon atoms, e.g. n-dodecyl mercaptan, the commercially available mixed tertiary mercaptans containing from 12 to 16 carbon atoms, thiophenol, alphaor beta-thionaphthol and the like.
• the polymerization can be effected within a wide range of temperatures; for example, within the range from 5 to 70 C. The above method conveniently results in the formation of polymer in the form of a latex or suspension of small drops or globules.
• the synthetic latex thus prepared is ready for use as a non-woven fibrous material saturant or impregnant without the necessity of neutralization, or alternatively the polymerization may be eifected using well known anionic or non-ionic emulsifiers, followed by neutralizing or alkalizing of the latex, e.g. with ammonium hydroxide, to pH 7 or above without coagulation and with retention of the enhanced adhesiveness and fiber bonding property.
• nitriles such as acrylonitrile
• when copolymerized in amounts of from 10 to percent, preferably 15 to 35 percent, with at least percent of the diene, and 1 to 5 percent of the polycarboxylic acid provide high internal bond in the impregnated fibers with excellent oil and solvent resistance.
• styrene and substituted styrenes amounts of from 10 to 75 percent, preferably 15 to percent, may advantageously be used.
• alcohol esters of acrylic and alpha-substituted acrylic acids such as methyl methacrylate
• copolymer latices herein described in admixture with other copolymers in emulsion form for the unifying of non-woven fibrous articles such as diene-nitrile and dienestyrene copolymers, and other copolymers containing carboxyl groups derived from monocarboxylic acids, such as diene-nitrile-methacrylic acid, diene-styrene-methacrylic acid copolymers.
• substantial amounts of the other copolymers e.g. up to about half of the mixture, may be utilized without undue decrease in the development of this property in the impregnated fibers.
• nitrile copolymers are made with a high diene content, for example, 70 percent or more, or are softened by use of modifiers for development of the desired elongation, they generally possess a lower than desirable tensile strength which prevents attainment of the desired elongation property.
• a strength imparting monomeric material such as acrylic and substituted acrylic acids, and other copolymerizable ethylenically unsaturated monocarboxylic acids, such as, crotonic acid, alpha-chlo-rocrotonic acid, hydroscorbic aid, cinnamic acid, m-chlorocinnamic acid, p-chlorocinnamic acid, acrylic acid, alphachloroacrylic acid, methacrylic acid, ethacrylic acid, vinyl thiophenic acid, alpha-furyl acrylicacid, vinyl furoic acid, p-vinylbenzoic acid, vinylnaphtho-ic acid, alpha-isopropenyl acrylic acid, alpha-styryl acrylic acid, Z-carbox
• a strength imparting monomeric material such as acrylic and substituted acrylic acids, and other copolymerizable ethylenically unsaturated monocarboxylic acids, such as, crotonic acid, al
• the presence of a monocarboxylic acid in the copolymer preparation enhances the internal bond strength, and their use in the invention is not dependent on any particular diene content or the presence of a nitrile in the copolymer.
• the polycarboxylic acid copolymers have been found to develop excellent elongation properties in the impregnated fibrous articles (with retention of the high internalbond strength) by the substitution of isoprene for butadiene 1,3 at diene charges of '70 percent or higher, while maintaining the monoolefinic monomer charge, such as nitrile, styrene or acrylic ester correspondingly low, that is below 30 percent and preferably about 20 percent of the monomer charge. Elongation so developed exceeds by as much as three-fold the elongation in papers saturated with butadiene-nitrile copolymer latices.
• the synthetic copolymer latices utilized in the invention are advantageously compatible with various resins used in compounding, such as wet strength resins, well known to those skilled in the art, for example, melamine-formaldehyde.
• various resins used in compounding such as wet strength resins, well known to those skilled in the art, for example, melamine-formaldehyde.
• the impregnated material is subjected to temperatures encountered in drying and in subsequent heat treatment. Such procedures are advantageous in the various applications of the present invention in that the internal bond strengths developed are usually enhanced rather than impaired.
• copolymer latices of the invention are further illustrated in the following examples in their application to unified paper backings for pressure-sensitive adhesive tapes, the backing being internally bonded with the acid copolymers deposited from aqueous dispersions.
• a tape is illustrated in the accompanying drawing which shows schematically a paper backing impregnated with the polycarboxylic acid-containing diene polymer of the invention'and a normally tacky pressure sensitive adhesive applied to one side of the backing.
• the invention has application to various fibrous masses, webs, flexible and rigid sheeting, and other fibrous articles which are customarily internally bonded, including non-woven textile fabrics made with fibers such as cotton, rayon, nylon, pol ester and other natural and synthetic fibers. Accordingly the examples are not to be construed as a limitation of the invention, but merely illustrative of specific embodiments. Unless otherwise noted, all references to parts or percentages in these examples refer to parts or percent by weight.
• Example I An aqueous solution consisting of parts of water, an emulsifying agent (4parts of sodium salt of an alkylaryl sulfonate), a chelating agent (0.02 part of ethylenediaminetetraacetic acid) and a peroxygen type initiator (0.15 part of potassium persulfate) was first placed in the reaction vessel. A modifier (0.8 part of mixed tertiary C to C mercaptans) was then placed in the reaction vessel, followed by 20 parts of acrylonitrile and then 3 parts of fumaric acid. Small amounts of the ingredients previously charged to the reaction vessel and adhering to the walls of the charging equipment were flushed into the reaction vessel with 5-0 parts of water, making a total of parts of water.
• an emulsifying agent 4parts of sodium salt of an alkylaryl sulfonate
• a chelating agent 0.2 part of ethylenediaminetetraacetic acid
• a peroxygen type initiator 0.15 part of potassium per
• the neutralized latex of the acidic copolymer was stabilized by the addition, with stirring, of 2.0 parts, referred to 100 parts of dry solids, of a potassium salt of a rosin acid.
• a potassium salt of a rosin acid To the latex was then added 1.0 part of antioxidant (a polyalkyl polyphenol) and 1.0 part of a melamineformaldehyde resin.
• antioxidant a polyalkyl polyphenol
• a melamineformaldehyde resin a melamineformaldehyde resin.
• the impregnated sheets were then withdrawn from the emulsion and excess emulsion removed by passing the sheets through squeeze rolls maintained under light pressure. After squeeze rolling, the impregnated paper was dried at a temperature between 140 and 176 F. for a period of about minutes, followed by heating for about 3 minutes at-about 300 F. The paper sheets were then subjected to a series of tests to determine the internal bond strength, tensile strength, and elongation properties developed by the impregnation with the particular copolymer. In addition, comparison tests were performed in the same manner, utilizing synthetic latex saturants devoid of polycarboxylic acid content.
• the polymer types included commercial butadiene-acrylonitrile copolymers with two different compositions 55 percent butadiene- 45 percent acrylonitrile, and 67 percent butadiene-33 percent acrylonitrile, butadiene-styrene copolymers containing 80, 72, and 50 percent butadiene and 20, 28, and 50 percent styrene, respectively.
• These comparison copolymers were prepared by well known methods of aqueous alkaline polymerization. The values of the developed properties are reported as the average of tests performed on three samples impregnated with the same copolymer.
• Internal bond teszs.-Internal bond strength is determined by measurement of the resistance to delamination of the, polymer-impregnated sheets. The test is identified as the Permacel Tape Corporation Ply Adhesion Test. Such tests were conducted by taking sample sheets and sealing heat-sensitive adhesive cloth-backed tape to the front and back surfaces of the sample. The sample was reduced to 1 inch by 8 inch size, and then placed in the jaws of a tensile machine. By operation of the machine the two outer pieces of cloth-backed tape were pulled apart at the rate of 12 inches per minute and a splitting or delamination of the impregnated paper sheet took place.
• the force required to continue the failure of the sheet by splitting or delamination was measured on a tensile testing machine (a Thwing Albert tensile machine with an autograph recording device), and this measured force was reported as the internal bond strength of the saturated paper in ounces per inch of width of the test sample.
• Tests for tensile strength of the impregnated paper were conducted by taking 1 inch by 8 inch samples of the impregnated paper and placing the ends thereof in the jaws of a standard tensile testing machine.
• the tensile strength was recorded by stretching the paper at the rate of 12 inches per minute in the machine direction of the paper I and the pounds per inch of width at which the sample failed in tension were recorded as the tensile strength of the sample.
• the percentage elongation was measured by recording the percentage of elongation which took place before failure of the sample, the elongation being measured in the machine direction of the paper sheet.
• LatexComposition BD/AN/FA percent by weight 73/24.25/2.75
• LateX Composition BD/ AN percent by weight, 67/33 1
• Semi-bleached kraft crepe paper 30# basis weight (480 sheets, 24 x 36 per ream) Brown Company 301
• LateXComposition BD/AN percent by HHHHH oooor-uc-cn PAPER WITH VARIOUS AMOUNTS OF T10;
• the invention provides a distinct advantage of permitting utilization of substantially smaller quantities of copolymer through reduction in the percent saturation of the fiber, while still obtaining the requisite internal bond strength.
• the unified non-woven fibrous articles in the invention are extremely well internally bonded and consequently are particularly suitable with normally adhesive material as a backing for pressure-sensitive adhesive tapes, printed tapes, sandpaper, and protective packaging.
• the high internal bond developed permits repeated application and removal of the pressure-sensitive adhesive tapes from surfaces to which it is adherent without splitting or delamination of the backing.
• the invention advantageously permits achievement of an excellent balance of properties heretofore not obtainable by varying the percent sat-
• the polycarboxylic acid containing copolymer latices permit pigmentation of the saturant for the production of colored tapes while satisfactory internal bond strength is maintained and larger quantities of pigments and fillers than could heretofore be tolerated may be utilized with retention of the high internal bond developed according to the invention.
• the articles of the invention are most suitable in end applications, such as masking tape where penein the practice 'of the invention, which are encompassed within its scope, including those which suggest themselves to those skilled in the art, and are to be regarded as within the scope of the claims hereafter appended.
• a latex composition of enhanced adhesiveness comprising an aqueous dispersion of a copolymer prepared by emulsion polymerization in aqueous acid medium of monomeric material containing from about 20% to about by weight of a conjugated butadiene; :from about 0.5% to about 20% by weight of at least one copolymerizable monoolefinically unsaturated dicarboxylic acid; and from about 10% to about 75% by weight of at least one monoolefinic monomer selected from the group consisting of acrylonitrile, styrene and methyl methacrylate, said monomer being copolymerizable with the conjugated diene and the copolymer containing free carboxylic acid groups in its polymer chain.
• bOXylic acid is selected from the group consisting of fumaric and itaconic acids.
• Brown 260-80 Brown MURRAY TILLMAN, Przmary Examzner, Miller 26029.7 10 WILLIAM H. SHORT, I. ZIEGLER, Kowalewski 26029.7 Assistant Examiners.

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• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
• Paper (AREA)
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  • 1959-07-17 GB GB24599/59A patent/GB935420A/en not_active Expired
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