Classifications

• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
  • D01D5/00—Formation of filaments, threads, or the like
  • D01D5/40—Formation of filaments, threads, or the like by applying a shearing force to a dispersion or solution of filament formable polymers, e.g. by stirring
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08C—TREATMENT OR CHEMICAL MODIFICATION OF RUBBERS
  • C08C1/00—Treatment of rubber latex
  • C08C1/14—Coagulation
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L13/00—Compositions of rubbers containing carboxyl groups
  • C08L13/02—Latex
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L61/00—Compositions of condensation polymers of aldehydes or ketones; Compositions of derivatives of such polymers
  • C08L61/20—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
• • 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
• • 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
  • D21H5/00—Special paper or cardboard not otherwise provided for
  • D21H5/12—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials
  • D21H5/20—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials of organic non-cellulosic fibres too short for spinning, with or without cellulose fibres

Definitions

• the invention relates to a process for the preparation of a fibrous binding agent for non-woven materials, in which a latex of a polymer or copolymer containing carboxyl groups is fiocculated with a water-soluble cationogenic polymer substance.
• non-woven material is well understood in the art and describes a productwith a self-sustaining, smooth structure, mainly composed of fiber that may or may not be linked together by a binding agent.
• fibers to be used for this purpose there may be mentioned, for instance, natural, vegetable and animal fibers modified natural fibers, regenerated natural fibers like rayon fiber, inorganic fibers like asbestos, glass and slag wool, synthetic fibers or mixtures thereof.
• non-woven materials For the manufacture of non-woven materials by a wet process from a suspension in water of regenerated cellulose fibers, synthetic fibers or inorganic fibers, it is necessary to add a binding agent to obtain cohesion between the fibers. This cohesion is required during the production of the non-Wovens in order to pass them through the machine when wet. In addition, it is necessary for the nonwovens to be sufiiciently strong for many end uses when they are still wet.
• a process is often used in which fibrous particles of a polymeric substance are added to the fiber suspension.
• a process has been described in which such finely divided fibrous particles 3,776,812 Patented Dec. 4, 1973 may be obtained by precipitating a synthetic polymer from a solution by means of a liquid, that does not dissolve the polymer, while applying high shear.
• the binding agent is prepared by precipitating a latex of an acrylic or a vinylic copolymer, preferably by adding the latex to a solution of a precipitating agent in water.
• Salts of polyvalent metals, particularly alum, and/or cationic organic compounds, particularly cationic polymers, are mentioned as precipitating agents.
• Additives may also be added to the latex to be precipitated, for instance, polyacrylic acid and salts thereof or carboxymethyl cellulose. The additive accomplishes the formation of elongated, fibrous, frayed particles.
• the co-precipitate thus formed has, on the one hand, a detrimental effect on the dehydration speed of the non-woven web in the paper machine.
• this finished non-woven web contains a certain amount of salts and hydrophilic polymers. These unwanted constituents have to be washed away in order to decrease the hydrophilic properties of the non-woven, because it would otherwise have too little strength when wet.
• the binding agent obtained according to this known process is therefore unsuitable for the production of a proper.non-woven from natural fibers.
• a highly suitable fibrous binding agent can be obtained when (a) a latex of a polymer having carboxyl groups or a latex containing a polymer having carboxyl groups and one or more polymers without carboxyl groups, the content of carboxyl groups of which amounts to 0.02-10 percent by weight calculated on the total amount of polymer or polymers, is mixed with (b) an aqueous solution of a cationic polymeric substance at a pH of 6-9, and by causing, after sixty minutes at the most, the finely divided particles formed to be converted into fine, fibrous particles by means of adjusting the pH of the mixture to 2-4 with stirring, and taking care that the solids content of the mixture finally amounts to 0.0l-l0 percent by weight.
• the process is preferably carried out in such a way that the mixture of latex and solution of cationic polymeric substance has a solids content of 0.1-5 percent by weight.
• a latex of a polymer having carboxyl groups means an aqueous dispersion of an elastomeric polymer or copolymer into which carboxyl groups have been introduced by methods well known, per se.
• the dispersed polymers may be natural polymers, modified natural polymers, synthetic polymers, or copolymers.
• Synthetic polymers or copolymers may both be obtained by addition polymerization and polycondensation. Latices of copolymers of butadiene and styrene, of butadiene and acrylonitrile, and of acrylic and methacrylic esters are preferred. The molecular weight of the polymers or copolymers is of no importance. Either the ratio of the monomers in co-polymers is essential. The only requirement is that a latex of an elastomeric polymer or copolymer having carboxyl groups be used.
• latices used in the present process are those described in British Pat. No. 824,286 to The B. F. Goodrich Company. This patent describes the preparation of latices of carboxyl-containing elastomers by the copolymerization of an olefinically unsaturated carboxylic acid with a diene. In a similar way latices of polymers having carboxyl groups may be prepared from unsaturated carboxylic acids without using comonomers.
• the content of carboxyl groups of the polymer, or mixture of polymers, dispersed in the latex should amount to 0.02- percent by weight. When the content of carboxyl groups is lower, fibrous particles are indeed obtained, but they are less stable both in mechanical and chemical respects. When the content of carboxyl groups is in excess of ten percent by weight there is too much of the cationic flocculation agent required, which would render the process less attractive economically. In addition to this there are at the moment no latices available having a higher content of carboxyl groups.
• the carboxyl groups must not be esterified, but may be neutralized, for instance, by means of an alkali metal or ammonium ion. Upon acidification to pH 2-4 in the second phase of the process the free carboxyl groups are formed.
• the latex may also contain one or more polymers without carboxyl groups, i.e., a mixture may be used of a latex of a polymer having carboxyl groups and one or more latices of polymers without carboxyl groups, provided that the content of carboxyl groups, calculated on the total amount of polymers, amounts to 0.02-10 percent by weight.
• polymers having carboxyl groups which may be dispersed in latices to be used as starting material, are mentioned: copolymers of acrylic and methacrylic esters, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyethylene, polypropylene, copolymers of butadiene and styrene, and of butadiene and acrylonitrile.
• the polymers or copolymers without carboxyl groups which may be used together with those having carboxyl groups differ from the last-mentioned polymers or copolymers in that a hydrogen atom has been substituted for the carboxyl group. It should be understood, however, that when a polymer or copolymer without carboxyl groups is used it need not be similar to the polymer or copolymer having carboxyl groups which is present in the latex. For instance, a copolymer of butadiene and acrylonitrile having carboxyl groups may be used together with a polyvinyl chloride without carboxyl groups.
• the latices may contain anionic and/or non-ionic stabilizing agents.
• the latices may contain additives, like antioxydants, anti-foaming agents, accelerators, etc. Stabilizing agents, antioxydants and accelerators have been described in the book of D. C. Blackley, High Polymer Latices, vol. 1, chapter II, par. 6, 4 and 3 respectively.
• Suitable anti-foaming agents are those known in the art such as Antifoam A and other compounds on a silicone basis.
• Polyamides, polyamines, polyimines or copolymers thereof, which may be cross-linked, for instance with epichlorohydrin, are used as water-soluble cationic polymeric substances by which the polymers of the latex are fiocculated.
• Particularly suitable are cationic urea-formaldehyde resins and melamineformaldehyde resins and deri at e o s a itline, such d ya d am cle-formaldehyde resins.
• Cationic modified starch may also be used.
• the water-soluble cationic polymers may be prepared according to the process described in US. Pats. Nos. 2,786,823, 2,926,154 and 3,215,654 and in Dutch Pat. No. 110,447.
• the cationic polymers used are mostly low molecular weight compounds, which are used in paper making as retention agents or as wet strength agents. Typical examples of such polymers are Kymene 557 (manufactured by Hercules Inc.) and Urecoll K (manufactured by Badische Anilin-und Soda Fabrik A. G. at Ludwigshafen- Rhein, Western Germany).
• Three-fifteen percent by weight of cationic polymer calculated on the solids of the latex is preferred. Higher percentages may also be used, however, e.g., up to fifty percent by weight. Flocculation may occur in percentages lower than three percent by weight, but there occurs insufficient cross-linking of the binding agent during the subsequent heat treatment. In this case the water resistance is not sufficient.
• the cationic polymeric substances are bound to the polymers of the latex containing carboxyl groups, the carboxyl groups being neutralized by formation of salts with the cationic groups, the flocculate of the polymers thus being formed.
• a binding agent is obtained which imparts an extremely high wet strength to non-woven web on the wire of the paper machine, right at the beginning of the process. That in itself is a great advantage from the viewpoint of workability of the non-woven web in the paper machine before the dryer.
• a cross-linking reaction during the heat treatment when the web is dried, between the carboxyl groups of the polymer from the latex and the cationic groups of the flocculating agent. The strength of the non-woven, both when dry and wet, is increased even more by this, and an excellent resistance to washing and dry cleaning is also obtained for this reason.
• the non-Wovens manufactured according to it are ready for use immediately, without an after-treatment being required.
• the process according to the invention is preferably carried out as follows:
• the latex is put into a mixing vessel provided with a stirrer.
• the latex is diluted, with stirring, with such an amount of water that the content of solids of the final mixture will have the desired value.
• a solution of the cationic polymeric flocculating agent is added to the water, care being taken that the pH of the mixture in the vessel is maintained at about 6-9.
• An extremely fine pre-flocculate is formed during this mixing.
• the particle size of the pre-flocculate is generally less than 50 micron and is therefore too small to be used as binding agent for non-wovens.
• the second phase of the process must be carried out. That is to say that the pH of the liquid has to be adjusted to 2-4 with normal stirring Within sixty minutes. If this is done after a longer period than sixty minutes, there is a danger of agglomeration of the fine particles to coarser particles than do not have the desired fibrous shape.
• fine fibers are formed from the fine particles of the pre-flocculate, said fibers having a length of 50-500 micron and a ratio between length and width of 2:1 to 10:1, provided care has been taken that the solids content of the mixture amounts to 0.01-10 percent by weight, preferably 0.1-5 percent by weight.
• Inorganic acids may be used for decreasing the pH, such as hydrochloric acid, sulfuric acid, and nitric acid.
• the binding force depends i.a. on the surface of the :flocculated binding agent. This surface is greater per unit weight as the particles are smaller. As has been stated, there is a minimum limit to the size of the particles.
• the range of particle size should be from 50 to 400 microns. The minimum limit depends on the pore size of the nonwoven web to be bound.
• the size of the particles can be regulated by controlling the conditions during the flocculation, such as pH, concentrations, temperature, etc., within strict limits. Particle size is increased with decreasing pH, increasing concentrations and increasing temperature.
• the components may also be added in a reversed order, but again there is the possibility that the fibrous flocculate will have a less even structure and size, which does not improve the strength properties of the non-Wovens manufactured with them. It is also possible to add both the latex, which may or may not have been diluted, and the solution of the cationic polymeric substance, each from a storage vessel, to a mixing vessel where stirring takes place.
• the suspension of fibrous particles obtained according to the invention can be used immediately as a binding agent, either by mixing with a suspension of fibers to be bound, or by adding said fibers to the suspension of the binding agent.
• the fibrous binding agent can, however, also be separated from the suspension, be packed as a moist mass, stored, transported, and subsequently used.
• the fibrous flocculate obtained according to the invention will stand up to mechanical forces, changes in pH and chemicals.
• the formation of the fibers is therefore an irreversible process. Once the fibers have been formed, however, they may be used as binding agent and mixed with any fiber mixture, whatever composition this mixture may have.
• a fibrous binding agent obtained according to the invention has excellent binding properties as compared with natural, regenerated, inorganic and synthetic fibers and mixtures thereof. It is highly suitable for the production in the wet process of non-woven materials having an extremely low base weight (-50 g./m.
• the non-woven materials are manufactured from an aqueous suspension of fibers in a paper machine, preferably of the inclined screen type.
• the fibers may be inorganic fibers such as glass fibers, fibers of cellulose and regenerated cellulose, synthetic fibers such as polyamide, polyester polyacrylic and polypropylene fibers and copolymer fibers.
• the length of the fibers may vary from 3 to 25 millimeters, the preferred length being about 6 millimeters.
• the ratio of length to diameter of the fibers should be no more than 500:1.
• the concentration of the fibers in the aqueous suspension should be no more than 0.1% by weight.
• the binding agent is added to it in an amount of up to 50% by weight, preferably to 35% by weight, calculated on the dry weight of the fibers.
• Hand formed sheets of non-woven materials may be manufactured in a similar way in a laboratory sheet forming apparatus.
• Polyamide fibers (length 6 mm., 1.5 den.) are stirred in water at a concentration of 0.1% by weight in a high speed mixer at 2800 rpm.
• the suspension obtained is diluted to a total volume of 10 liters in a laboratory sheet forming apparatus.
• the Ifibres particles of the binding agent prepared in the above-mentioned way are added in an amount of 50% by weight, calculated as dry binding agent on the weight of the dry fibers.
• After thorough mixing the suspension is sieved while stirring, thus forming a wet fibrous web on the sieve plate.
• the wet sheet is taken from the sieve plate and dried during 5 minutes at a temperature of C. After drying the non-woven sheet is heated during 2 minutes at a temperature of to C.
• the non-woven obtained has a basis weight of 50 g./m. The retention of binding agent in the nonwoven appears to be 95-100 percent.
• the tensile strength of the non-woven web when dry amounts to 4.8 kg./5 cm. and the elongation at break amounts to 33 percent.
• the wet strength amounts to 82 percent of the dry strength.
• the obtained non-woven appears to be flexible and strong.
• the non-woven can stand up very well to yellowing, washing and dry cleaning.
• the retention of binding agent amounts to 97 percent.
• the tensile strength of the membrane when dry is 4.5 kg./cm. and the elongation at break 28 percent.
• a process for the production of non-woven fibrous materials comprising mixing fibers to be bound with a fibrous binding agent to form an aqueous fiber suspension, dehydrating said suspension to form a wet fibrous web and heating the web, said fibrous binding agent being formed by mixing a latex of a polymer having carboxyl group selected from the group consisting of carboxyl group containing butadiene-styrene copolymers, butadiene-acrylonitrile, copolymers, acrylic and methacrylic ester copolymers, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyethylene, polypropylene, and wherein the content of the carboxyl groups amounts from 0.02 to percent by weight calculated on the total amount of polymer with an aqueous solution of a cationic polymer substance selected from the group consisting of polyamides, polyamines, and cationic modified starch wherein the amount of said cationic polymeric substance is from 3 to 50 percent

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Mechanical Engineering (AREA)
• Dispersion Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Paper (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
• Nonwoven Fabrics (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=35285437

Family Applications (1)

Country Status (7)

Cited By (13)

Families Citing this family (4)

• 0
  • NL NL133246D patent/NL133246C/xx active
• 1967
  • 1967-04-28 NL NL6706028A patent/NL6706028A/xx unknown
• 1968
  • 1968-10-07 BE BE721936D patent/BE721936A/nl not_active IP Right Cessation
  • 1968-10-18 CH CH1557468D patent/CH1557468A4/xx unknown
  • 1968-10-18 CH CH1557468A patent/CH560785A/de not_active IP Right Cessation
  • 1968-10-18 DE DE19681803897 patent/DE1803897A1/de not_active Withdrawn
  • 1968-10-21 GB GB49900/68A patent/GB1185268A/en not_active Expired
  • 1968-10-24 FR FR171247A patent/FR1589924A/fr not_active Expired
• 1971
  • 1971-11-17 US US00199797A patent/US3776812A/en not_active Expired - Lifetime

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