JPS6240480B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a high-strength fibrous nonwoven sheet-like article and a method for manufacturing the same. The fibrous nonwoven sheet-like article referred to herein refers to articles such as paper, cardboard, hard board, and insulating board. BACKGROUND OF THE INVENTION The use of latex as a wet end or beater additive in paper manufacturing is well known. Generally, the latex is an anionic latex, but a water-soluble cationic precipitation aid is used together. Since the pulp is slightly anionic,
It is believed that low charge density cationic latexes must be used to achieve good precipitation on fibers without the use of precipitation aids. Mixtures of anionic and cationic wet end additives, both of which are water soluble, are known. However, mixtures of cationic latexes and water-soluble anionic polymers as wet final additives, especially latexes with particles with a high density of PH-independent bonded charges at or near the particle surface, have been proposed in the prior art. It has not been done or suggested. SUMMARY OF THE INVENTION The present invention provides an inorganic polymer comprising a mixture of (a) paper-grade fibers, (b) a latex of cationic water-insoluble copolymer particles, and (c) a water-soluble anionic polymer (co-additive). In the method for producing woven sheet-like articles and non-woven sheet-like articles, a special latex is used as the component (b), and this is used in combination with a specific component (c) to produce a non-woven sheet-like article. It allows for a high level of latex to be loaded onto the sheet-like article (with little or no latex in the recycled liquid), which results in a high strength product with greater internal bond strength than that of conventional methods. It is based on the unexpected discovery that non-woven sheet-like articles can be obtained. Generally speaking, each of the above components (b) and (c) in a broad sense is known per se. However, the use of a special component (b) as described above in combination with a specific component (c) and the remarkable effects brought about thereby are totally unexpected and not suggested by the prior art. More specifically, in one aspect, the present invention comprises: (a) an aqueous slurry of negatively charged water-insoluble natural or synthetic fibers; (b) a cationic water-insoluble copolymer as particles; a nonionic organic compound surrounded by a shell of a thin layer of a water-insoluble copolymer having a bonded charge of pH-independent cationic groups in an amount of 0.07 to 0.6 milliequivalents per gram of copolymer at or near the surface of the Shell consisting of polymer core
Latex as a core structure particle and (c) having a degree of polymerization of 3000 or more, an effective charge of 0.3 to 8 milliequivalents per gram of polymer, and an acrylic carbon-carbon chain center axis, and in the presence of polyvalent metal ions at a pH of 4 to 7. mixing with a co-additive that is a water-soluble anionic polymer capable of retaining its water solubility to form an aqueous suspension; removing water from the aqueous suspension to form a tight mat; Provided is a method for producing a high-strength fibrous nonwoven sheet-like article, which comprises heating and drying mat; and wherein the copolymer particles of the latex are deformable at the operating temperature. It is something. In another aspect, the present invention includes (a) anionically charged paper-grade fibers; (b) a shell of a thin layer of a water-insoluble organic copolymer having a bonded charge of cationic groups unrelated to pH. 0.15 to 0.15 per gram of polymer in the nonionic copolymer core sticky latex
(c) 5 to 2000% calculated on a solid basis based on fiber weight for shell-core structure particle latexes with a bond charge of 0.6 milliequivalents, and (c) 3000 to 2000%
A co-addition which is a water-soluble anionic polymer of acrylamide with a degree of polymerization of 10,000 and an effective charge of 0.3 to 8 milliequivalents per gram of polymer and capable of retaining its water solubility in the presence of polyvalent metal ions at pH 4 to 7. 0.15 to 0.15 on a fiber weight basis
The present invention provides a high-strength fibrous nonwoven sheet-like article comprising a dry mixture containing 160%. Preferred Embodiments of the Invention Latex is added in an amount no less than necessary to reverse the charge on the fibers, but less than an amount that would exceed the ability of the fibers to retain a wet mat during operation.
This amount is usually solid based on the dry weight of the fiber.
0.5 to 2000%, preferably 10 to 100%. The charge density of the cationic latex particles is preferably about 0.1 to 0.6 milliequivalents per gram of copolymer;
0.15 to 0.5 milliequivalent is preferable. bond charge density
Latexes less than 0.1 meg/g tend to be insufficiently stable for some applications. The amount of co-additive is no less than that necessary to maintain essentially complete retention of the latex on the fibers, but less than an amount effective to substantially redisperse the components of the aqueous suspension. The optimum amount gives good strength with little redispersion. This amount usually ranges from 0.05 to 160% by weight, based on the dry weight of the fiber. The fibers may be any type of negatively charged, water-insoluble, natural or synthetic fibers that can be dispersed into an aqueous slurry, including coarse, low-grade "kus", ie, crude by-product pulp from unbleached chemical pulp. Either short fibers or long fibers or mixtures thereof can be used. Glass fibers, recycled paper, cellulose from cotton, linen straw, straw and similar materials are also applications. Particularly useful fibers are cellulose and wood cellulose fibers commonly known as various wood pulps such as mechanical pulp, steam-heated fiber pulp, chemical pulp, semi-chemical pulp, and chemical pulp. Examples include groundwood pulp, unbleached sulfite pulp, bleached sulfite pulp, unbleached sulfate pulp, and bleached sulfate pulp. On a solid basis calculated from this paper pulp and dry fiber weight, 5~
2000% latex and dry fiber weight basis 0.15~
A well-formed fibrous nonwoven fabric is obtained when using 160% by weight of co-additive. To operate in this manner, the latex component is rather insensitive to the copolymer component as long as the glass transition temperature (Tg) of the copolymer is lower than the temperature used in the operating process. Polymers with Tg up to about 100°C can be used, but the Tg can be as low as room temperature or below, -80°C. However, if the latex loading is greater than about 100% based on fiber, the wet mat can be easily handled using a hard latex copolymer, such as a copolymer with a Tg above 0°C. However, the copolymer in the latex must be capable of deformation at the operating temperatures. Latexes have a non-ionic polymer core, such as a copolymer of monovinylidene aromatic monomer, aliphatic conjugated diene, and optionally other non-ionic monomers, that have a pH at or near the particle surface. It is represented by a particle latex having a structure in which it is surrounded by a thin film of a water-insoluble organic copolymer having a bonding charge as a cationic group unrelated to the cationic group, but is not limited thereto. One method for obtaining such a latex is to make an ethylenically unsaturated activated halogen monomer under emulsion polymerization reaction conditions slightly cationic due to the presence of an adsorbed cationic surfactant. The non-ionic organic polymer is copolymerized onto the surface of the particles. The resulting latex is reacted with a nonionic nucleophile to produce a latex suitable for use in the practice of this invention. The particle size usually ranges from 500 to 5000 angstroms, preferably 800 to 3000 angstroms. “Bond” used for groups or charges
(bound) means that they are not released under operating conditions. A convenient test is performed by dialysis against deionized water. "PH-independent group" refers to a group that is primarily in the ionized form over a wide range of PH, eg 2-12. Typical examples of such groups are sulfonium, sulfoxonium, isothiouronium,
Pyridinium and quaternary ammonium salts. "Effective charge" refers to the amount of charge that an ionizable group would impart to a polymer if it were completely ionized. "Non-ionic" is used herein to refer to monomers, and refers to monomers that are not inherently ionic and do not become ionic even by simple changes in pH. say. For example, monomers with amine groups are non-ionic at high pH, but adding water-soluble acids lowers the pH and forms water-soluble salts, so such monomers are not included. do not have. However, nonionic nucleophiles cannot be similarly determined. Thus, when used with respect to nucleophiles, "nonionic" applies to such compounds that are nonionic under the conditions of use. For example, quaternary amines are included. Preferably, the co-additives used in the present invention have a degree of polymerization of 5000 or higher and an effective charge of 0.7 to 4.5 milliequivalents per gram of polymer. Such water-soluble polymers may be natural or synthetic. The upper limit on the degree of polymerization is not critical as long as the co-additive has the necessary solubility. In cases such as partially cross-linked polymers, DP (degree of polymerization) values cannot be measured. Typical co-additives include water-soluble high molecular weight acrylamide polymers with pendant anionic groups such as carboxyl, sulfate, sulfonate, etc., sodium polystyrene sulfonate, partial hydrolysis of vinyl acetate and acrylic acid. sulfated polyvinyl alcohols, polyvinyl acetate polymers with pendant anionic groups such as carboxyl, sulfate and sulfonate, and copolymers of hydroxyethylene acrylate and sulfoethyl methacrylate. There is. Various known methods can be used to obtain such anionic acrylamide polymers. For example, polyacrylamide can be hydrolyzed to varying degrees. Other methods include replacing substituted acrylamide monomers such as 2-acrylamido-2-methylpropanesulfonic acid with α-β-ethylene compounds such as acrylic acid, methacrylic acid, fumaric acid, maleic acid, and itaconic acid. There is a method of direct copolymerization with other hydrophilic monomers such as unsaturated carboxylic acids. Preferred polymeric co-additives have molecular weights large enough to agglomerate the particulates yet small enough to avoid malformation. If the degree of polymerization is less than 3000, flocculation will be inadequate and water release and retention will be poor. The degree of polymerization
If it exceeds 10,000, agglomeration is quite good, but paper formation for some types of paper is insufficient. The optimum charge of the co-additive depends to some extent on the hardness of the water used,
That is, it depends on the concentration of polyvalent cations such as Ca ⁺⁺ in the water. Polymers with low effective charge content, generally less than about 1 milliequivalent of effective charge per gram of polymer (meq/g), perform very well in hard water. However, in soft water, good results are obtained with anionic coadditives having more than 1 meq of effective charge per gram of polymer. For good paper formation, the nonionic copolymer core of the latex used in the practice of this invention contains 20 to 50% aliphatic conjugated diene (preferably 1,3-butadiene), a monovinylidene aromatic compound (preferably styrene), 20
80% to 80% of polar nonionic ethylenically unsaturated monomers and 0 to 5% of other ethylenically unsaturated nonionic monomers which are water-insoluble in homopolymer form.
Preferably, it contains 25% to 25%. Monovinylidene aromatic compounds include styrene, substituted styrene, (e.g. halogen, alkoxy,
Typical examples include styrene (with cyano or alkyl substituents), vinylnaphthalene, etc. Special examples are styrene, alpha-methylstyrene, aromatic-methylstyrene, aromatic-ethylstyrene, alpha-aromatic-dimethylstyrene, aromatic, aromatic-dimethylstyrene, aromatic-t-butylstyrene, methoxystyrene. , cyanostyrene, acetylstyrene, monochlorostyrene, dichlorostyrene, other halostyrenes and vinylnaphthalenes. “Monovinylidene aromatic” monomer or compound means that the aromatic ring in each molecule of the monomer or compound has the formula:

[Formula] (where R represents hydrogen or lower alkyl having 1 to 4 carbon atoms) is bonded. Aliphatic conjugated dienes for use in the practice of this invention include butadiene and substituted butadienes and other acrylic compounds having at least two sites of ethylenically unsaturation separated from each other by a single carbon-to-carbon bond. Specific examples include isoprene, chloroprene, 2-
3-dimethylbutadiene-1,3-methylpentadiene and especially 1,3-butadiene (often simply referred to as butadiene). Polar nonionic ethylenically unsaturated monomers include acrylamides such as acrylamide and methacrylamide: β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl methacrylate, 4-hydroxybutyl They are represented by hydroxyl-containing esters of α,β-ethylenically unsaturated aliphatic monocarboxylic acids such as acrylate and 5-hydroxypentyl methacrylate. Other ethylenically unsaturated nonionic monomers which are water-insoluble in homopolymer form are lower acrylate and methacrylate esters such as methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate. and unsaturated nitriles such as acrylonitrile and methacrylonitrile. In one method for producing latexes useful in the practice of the present invention, known raw latexes of non-ionic polymers of monovinylidene aromatics and aliphatic conjugated dienes are activated halogen monomers or monomers thereof. or activated halogen monomers together with one or more hydrophobic monomers to form essentially residual monomers. is added to the raw latex containing no monomers and continues to initiate the polymerization reaction of the added monomers until substantially complete conversion and enveloping them in a thin layer of copolymer of ethylenically unsaturated active halogen monomers. . Particle size (diameter) 800
The resulting latex, having a thickness of 3,000 angstroms, now consists of raw latex particles surrounded by a tie layer having a thickness of about 100 angstroms from a copolymer monolayer. The above latex then reacts with a low molecular weight non-ionic water-stable nucleophile that can diffuse into the aqueous phase to form PH-independent cationic groups chemically attached to or near the particle surface.
That is, polymer particles containing onium ions are produced. Typical nucleophilic compounds are pyridine, quinoline, inquinoline, tetramethylthiourea, tetraethylthiourea, hydroxyethylmethyl sulfide, hydroxyethylethyl sulfide, dimethyl sulfide, diethyl sulfide, di-n-propyl sulfide. , methyl-n-propyl sulfide, methylbutyl sulfide, dibutyl sulfide, trimethylene sulfide,
thiacyclohexane, tetrahydrothiophene,
N-methylpiperidine, N-ethylpyrrolidine,
N-hydroxyethylpyrrolidine, trimethylphosphine, triethylphosphine, tri-
n-butylphosphine, trimethylamine, triethylamine, tri-n-propylamine, tri-isobutylamine, hydroxyethyldimethylamine, butyldimethylamine, trihydroxyethylamine, triphenylphosphine, and N・N・N- Dimethylphenethylamine. To carry out the reaction between a nucleophilic compound and latex particles having an active halogen chemically bonded to the surface thereof, the nucleophilic compound is added to the latex, either by itself or in the form of a solution thereof, while gently stirring the latex. Stir slowly during the reaction, and stop stirring after the compound is dispersed in the latex. The reaction is 0 to
Although it can be done at a temperature of 80°C, it is convenient to do it at atmospheric temperature. The reaction occurs spontaneously due to the reactivity of the active halogen and the nucleophile. The reaction is preferably allowed to proceed until the resulting chemically bound cationic groups produce a very large amount of colloidally stable product.
A catalyst is usually not required, but small amounts of iodine ions can be used to react with less reactive substances. When the reaction reaches the desired point, any excess nucleophilic compound is removed by standard methods such as dialysis, vacuum distillation and steam distillation. Other PH-unrelated cationic groups can be replaced by further reaction with the cationic group chemically bonded to the latex particles as described above. For example, a cationically constructed particle latex with sulfonium groups chemically bonded to the particles at or near the particle surface may contain 20 to 80
C., preferably at ambient temperature for a sufficient period of time to oxidize some or all of the sulfonium groups to sulfonium groups. Such treatment reduces the odor of the latex. To obtain good results in this oxidation reaction, an excess of hydrogen peroxide is used, for example 2 to 10 moles of hydrogen peroxide for each mole of sulfonium groups. Latexes are antifoam agents, co-solvents, pigments and
Common additives such as PH regulators can be included. It is preferred that the latex be soap-free, but amounts up to about 0.1 milliequivalents per gram are acceptable. The process for preparing the product of the invention is preferably carried out as follows: a dilute aqueous suspension of the fibers is prepared in a conventional manner by
Make the concentration between 6% and 6%. Add the appropriate concentration of latex to the feed concentration and stir the mixture. Stir for at least 2 minutes depending on the equipment used. The suspension water is then diluted with more often white water from the operation. The co-additive is added as an aqueous solution, usually at a concentration of less than 1% solids, and the mixture is stirred to ensure thorough mixing. Co-additives can be added at any time since they are usually the final ingredients added to the wet process. Add it at any appropriate time. Other optional components of the nonwoven sheet article forming composition in the wet final step of the method of the invention include pigments,
There are fillers, hardeners, waxes, oils and other common additives known in the papermaking art. A nonwoven sheet-like article is formed by pouring the resulting suspension onto a perforated support such as gold to form a wet mat, which is then dehydrated and dried by heating. The dewatering process may include a draining process and a wet compression process. Compression and heating may be performed simultaneously to form a nonwoven sheet-like article. Separately, it can also be compressed at ambient temperature and then heated and dried. Optionally, compression, molding, modification and curing steps may be included. The temperature of thermal compression, curing and modification or other heating processes is between 100℃ and 250℃
However, higher or lower temperatures can also be used. For the production of nonwoven sheet articles, a foredrinier machine, a cylinder machine, or experimental sheet forming equipment are convenient. The products of the process of the invention have improved internal bond strength compared to those of conventional processes. At low concentrations of latex and within the acceptable variables of practicing this invention, the degree of bonding of the polymer particles to the fibers is more sensitive than the nature of the polymer composition. At high concentrations, if sufficient heat is applied to melt the latex particles, the properties of the resulting product will depend significantly on the nature of the polymer phase. The method of the present invention has a better retention rate than the conventional method.
That is, it is advantageous in that a larger amount of suspended solids can be obtained from an aqueous suspension. During this process, the system has good stability against shear forces, allowing mechanical treatment without redispersion of the solids. The solids in the wastewater of this process are therefore low in concentration and highly recyclable, minimizing the release of pollutants into the environment. The "formation" of a sheet of paper refers to the homogeneous distribution of fibers in the paper. Bad formation occurs when the fibers clump together or clump together, creating alternating thick and thin spots on the paper. Poor formation not only detracts from the aesthetic properties of the paper, but also tends to degrade planar strength, such as tensile strength. Poor formation creates uneven surfaces and causes poor printability. All degrees of polymerization herein are weight averages unless otherwise specified. The following examples are illustrative of how the invention may be carried out, but should not be construed as limiting the invention. All parts and percentages are by weight unless otherwise noted. A number of latexes used in the examples are shown in the table. The monomers for the basic latex were prepared under emulsion polymerization reaction conditions, using dodecylbenzyldimethylsulfonium chloride as an emulsifier in an amount of 1.8 to 2.5% based on the total monomer weight, and
Polymerization was carried out using 0.2% dodecanethiol as a chain transfer agent and 0.5% α·α′-azobisisobutyronitrile as a catalyst. The basic latex particles were then capped by continuously adding the types and amounts of cap monomers indicated in the table per 100 g of total monomer component over a period of about 1 hour. (Pucked). The same type of catalyst was used in a cap reaction at a higher temperature of about 70°C with stirring. The latex product was then reacted with an excess of the nucleophile 2-(dimethylamino)ethanol (for quaternary ammonium bound charging) at 70°C to obtain a desired amount of bound charge, and the excess nucleophile was distilled off by steam distillation. Removed. For sulfonium bound charging, the nucleophile was dimethyl sulfide, the reaction temperature was 50°C, and excess nucleophile was distilled under vacuum. The resulting constituent particle latex is shown in the table.

[Table] The tests mentioned in the examples were conducted in the following manner: Tensile value The tensile value was measured according to TAPPI standard T494-OS-70, but the value was the average of 3 samples instead of 10 samples, and the jaw spacing was 20.32. The break length was recorded in meters as 5.08 cm instead of cm. Canadian Standard Freedom (CSF) values were measured according to TAPPI Standard T227-M-58, with method modifications as indicated. Formability The usual method for measuring formability is to measure the uniformity of fiber distribution (formability) on a scale of 1 to 10, with 1 being the best and 10 being the worst. A visual comparison was made with a standard sheet. Alternatively, commercially available optical instruments can also be used to measure formability. Peeling Resistance The internal bond strength of the product was measured by a peeling resistance test.
This test consisted of placing a 1 inch wide piece of the product under test between two pieces of adhesive tape with sufficient adhesion and testing whether damage to the paper occurred when the two pieces of tape were pulled apart. Peeling was first measured manually using an Instron tensile tester at a jaw pulling rate of 30.48 cm/min. Two samples of each were tested for average peel strength over a length of approximately 10.16 cm. The average of the two samples was recorded in ounces per inch of width and abbreviated as oz/in. This value was converted to metric units, ie, grams per 2.54 cm, and is shown in brackets. If a different tape was used in the test, the new tape was corrected for the original tape and the values reported were from the original tape. Example 1 785ml of mechanically extracted fibers heated with steam
A pulp with a Canadian standard degree of freedom of 24% solids was diluted to 10% solids with water having a hardness of 10.8 (ppm as CaCO ₃ ) and an alkalinity of 48 (ppm as CaCO ₃ ). The components shown in the table were added to this fiber suspension in the order shown, and after stirring for the time shown, it was sent to the next step. Approximately 3% Latex A was required to reach the pulp charge transition point.

[Table] (a): Dry standard calculated from fiber dry weight. (b): The following hydrolyzed polyacrylamide,
The co-additive is a hydrolyzed polyacrylamide with a degree of polymerization of 25,000 and an effective charge of 1.94 milliequivalents per gram of co-additive. The resulting suspension was passed through a Büssfner funnel under vacuum with a water aspirator and then filtered onto paper (dia.
12.5 cm). This wet sheet was removed from the funnel, placed between two sheets of paper and four sheets of blotting paper, and heated to 1715 psig in a Williams press.
(120Kg/cm ² ). The sheet with the paper and blotting paper removed was dried on a hot plate at 165°C for 5 minutes. The drying sheet was kept at a humidity of 50% and a temperature of 23℃ before testing.
Conditions were adjusted by placing them in a chamber for at least 2 hours, usually overnight. The turbidity of the liquid was examined using a spectrophotometer to measure water transparency. The wavelength of light used was 425 nm, and the cuette diameter was 19 mm. The tensile values, draining times and liquid clarity (percent transmission) of the nonwoven sheet articles are shown in the table. Comparative Example 1C A sheet was similarly made using the same ingredients except for the latex and co-additives. Draining times, clarity and tensile values are given in the table.

[Table] *This is not an example of the present invention.
a = fracture length, meters.
Example 1 illustrates improvements in drain time, operational effluent (effluent) clarity, and product strength according to the present invention. Examples 2-10 For each example, unbleached Canadian softwood Kraft 7 with 1393 parts water and 400 ml Canadian Standard Freedom (CSF) with a hardness of 106 ppm (calculated as calcium carbonate) and alkalinity of 48 ppm.
(on a dry basis) was stirred at such a speed that the kraft just rotated gently. 1.4 parts of latex A (dry weight basis) was added to the suspension in which the craft was moving. After stirring for an additional 2 minutes at the same speed, a dilute aqueous solution (0.2% solids) of the specified co-additive was added in the amount shown in the table and stirring was continued for an additional 30 seconds. M/K the obtained mixture (PH7-8) using the dilution water described above.
It was made into a handmade sheet measuring 30.48 x 30.48cm on a model "Minnie Mill" handmade machine. The sheet and blotting paper are placed between two sheets of wool felt and put together through a press at medium speed to 80 psig (5.6 kg/cm ² ) to produce a handmade sheet with a solids content of approximately 37 to 38 lbs.
%. The compressed sheet was taken out from between the felts, blotted with paper, and dried in a dryer at 220°C (140°C). The product was wrinkle-free and had a solids content of approximately 95%. The co-additive used in the example had an effective charge (carboxyl) of 1.94 milliequivalents per gram.
It is a hydrolyzed polyacrylamide with a degree of polymerization of 25,000. Data are shown in the table. Comparative Examples 2C1-2G5, 5C and 8C Comparative Examples 2C2 and 2C4 were made in the same manner from components as described in Examples 2-10. The amount of latex was less than that needed to transfer the charge on the fibers used (5.5%). Comparative Examples 2C1, 2C3, 2C5 and 5C and 8C were made in a similar manner without co-additives. Data for comparative examples are shown in the table.

[Table] Example 11 The same amount of substances as in Example 2-10 except that the latex used in Example 2-10 was changed to Latex B (see table) and the same co-additive amount was changed to 0.6% based on the dry weight of the fiber. I made the sheet using the same method. This sheet was tested for peel resistance.
(See Table) Comparative Example 11 A sheet was made in the same manner using the same materials and amounts as in Example 11, except that Latex X was used in place of Latex B used in Example 11. Latexes B and X had the same average polymer composition, but latex B had a structured particle latex whereas latex X had a uniform composition throughout the particles as described above. Data are shown in the table for comparison with Example 11.

[Table] *This is not an example of the present invention.
Comparative Example 11C from the peeling resistance values shown in the table
Although the total charge is larger, Example 11 (embodiment of the present invention), which has bound charges only on the particle surface, has a much improved value than the method using latex, which has bound charges over the entire particle. I found out that it gives Examples 12-14 Sheets were made in the same manner as in Example 11, using latexes C, D and E in place of latex B in Example 11, respectively. These three latexes had different amounts of nucleophile (dimethylaminoethanol) that reacted with the capped latex, and therefore had different amounts of bonded charge.
Data are shown in the table.

Table of Contents Examples 12-14 show that as the bond charge on the latex increases, the internal bond strength of the product also increases. Examples 15-22 Sheets were made according to the method of Example 11, except that different latexes were used in the same proportions. The primary difference between latexes concerns the composition in the base latex that makes up the structured particle latex. (See table) Data are shown in the table. Comparative Example 22C Sheets were made in the same manner as Examples 15-22, but without the addition of latex and co-additives. The results are shown in the table.

[Table] In Examples 15-18, the sulfonium group is Example 1-
The present invention generates a bond charge rather than 14 quaternary ammonium groups and shows that the method can be operated over a wide range of compositions (wide range of Tg values) of latex polymers at approximately the same bond charge. illustrates the method. In this series of tests, the peel test shows that the internal bond strength of the product does not change much. Examples 19-22 have a high bonding charge in the latex and a change in the basic latex (core composition).
This illustrates that the value can be increased. As the polymer becomes harder (higher Tg value) in this series of tests, the measured peel resistance under this test condition decreases. However, if the heating time is increased from 1 minute to 12 minutes, the peeling resistance of Examples 20, 21, and 22 will decrease, respectively.
22.4oz/in (635g/2.54), 18.5oz/in (524g/
2.54 cm), and 14.8 oz/in (420 g/2.54 cm). These examples show that at high Tg values within the indicated range for the latex used, it is necessary to choose a high temperature and/or a long time, or conversely, under the given temperature and time conditions, it is necessary to choose a high temperature and/or a long time.
It is clear that a latex with a low Tg value should be used. Examples 23-28 Sheets were made as described in Example 11, except that different latexes were used in all of these Examples, and the co-additives themselves were varied, but in different amounts except for No. 25. The embodiment was not changed. The results are shown in the table.

[Table] Example 29 Hardness of 106 ppm (calculated as calcium carbonate)
and 1990 parts of water with an alkalinity of 48 ppm (calculated as calcium carbonate) and 10 parts of unbleached Canadian softwood kraft (dry basis) with 400 ml of Canadian Standard Freedom (CSF) at just the speed that the kraft is rotating. Stir gently. 90 parts of latex I (dry weight basis) was added to the moving kraft suspension. After rotating for an additional 2 minutes at the same speed, 33 parts of the specific co-additive was added as a dilute aqueous solution (0.2% solids) and stirred for an additional 30 seconds. The resulting mixture was made into handsheets (30.48 x 30.48 cm) on an M/K model "Minnie Mill" handsheet using the dilution water described above. The sheet was placed between two sheets of clean paper and four sheets of blotting paper and compressed on a Williams press at 136 psig (9.52 Kg/cm ² ). After removing the blotter and paper, the sheet was dried on a hot plate at 165°C for 5 minutes. The dried sheet obtained was so strong that peel resistance could not be measured using the method described herein. The co-additive used in this example was a hydrolyzed polyacrylamide with 1.94 milliequivalents of anionic groups (carboxyl) per gram and a degree of polymerization of 5500. Example 30 Sheets were made using the same materials and amounts according to the method described in Examples 2-10. However, the same amount of co-additives was used as 0.1%, and the latex was prepared in batches from 65 parts of styrene, 30 parts of butadiene, 5 parts of acrylonitrile, and 4 parts of vinylbenzylmethyldodecylsulfonium chloride without adding any non-polymerizable surfactant. It was a latex made according to Patent No. 3873488. This latex has a solids content of 23.9%, a particle size of 1090 angstroms (measured by light scattering method) and a particle size of 0.072 angstroms per gram of polymer.
It had a milliequivalent bond charge. Estimated Tg is 25
It was warm at ℃. Sheet peel resistance is 19.3oz/in
(547g/2.54cm). This example illustrates the practice of the present invention using a latex having near the lowest amount of bonded charge suitable for the present invention and the use of a latex not produced by the method of making the structured particle latex. . Examples 31 and 32 Sheets were made using the same materials and quantities as described in Examples 2-10. However, the latex shown below was used, different co-additives were used in the amounts shown in the table, and the water used was deionized water. The latex has a solids content of 23% and a particle size of
880 angstrom core polymer consisting of 40% styrene and 60% butyl acrylate (core Tg =
-10°C) was a structured particle latex in which 100 parts were capped with 10 parts of a copolymer consisting of 33% vinylbenzyl chloride and 67% butyl acrylate. This is later reacted with trimethylamine to give a solid basis, a bond charge of 0.121 per gram of latex.
It became milli equivalent. The co-additive used in this example had a degree of polymerization of 20800.
and a hydrolyzed polyacrylamide with an effective charge of 3.48 milliequivalents (from carboxyl groups) per gram. Data are shown in the table. Comparative Examples 31C1 and 31C2 Sheets were made in the same manner as Examples 31 and 32. However, in 31C1, the latex and co-additives were excluded, and in 31C2, only the co-additives were gradually removed. The results are shown in the table.

[Table] *This is not an example of the present invention.
a = Calculated for dry standard fiber.
Examples 31 and 32 illustrate the invention using soft or deionized water, different co-additives, and a different composition of latex than other embodiments of the invention. Examples 33 and 34 106 ppm hardness (calculated as calcium carbonate)
Just kraft an aqueous suspension containing 1393 parts water with an alkalinity of 48 ppm (calculated as calcium carbonate) and 7 parts unbleached Canadian softwood kraft (dry basis) with 400 ml Canadian Standard Freedom (CSF). The mixture was stirred gently at the speed of rotation. To the moving kraft suspension was added 1.4 parts (dry weight basis) of the following types of latex: After stirring for an additional 2 minutes at the same speed, a dilute aqueous solution (0.2% solids) of the specified co-additive was added in the amount shown in the table and stirring continued for an additional 30 seconds. The resulting mixture was made into handsheets (30.48 x 30.48 cm) on an M/K model "Minnie Mill" handsheet using the dilution water described above. The handsheet was sandwiched between two sheets of wool felt with blotting paper and the sheet was compressed to a solids content of 37-38% through a press at a moderate speed and pressure of 80 psig (5.6 Kg/cm ² ). The compressed sheet was taken out from between the felt, the blotting paper was removed, and it was dried in a dryer at 22% (104°C). The product was wrinkle-free and had a solids content of approximately 95%. The latexes used in the above tests were (a) 80% core copolymer of 35% butadiene and 65% styrene; and (b)
A structured particle latex with a 20% encapsulating layer consisting of 35% butadiene, 15% styrene and 50% vinylbenzyl chloride, which after polymerization
-(dimethylamino)ethanol to produce a bound quaternary ammonium charge in the latex with 0.365 milliequivalents per gram of polymer. The co-additive (A) used in this example is a hydrolyzed polyethyleneamide with a degree of polymerization of 5500 and an effective charge of 1.94 mequivalents per gram. For comparison with the above examples of the invention, sheets were made in the same manner, except that instead of co-additive (A), co-additive (B) was used, i.e. with the same effective charge but with a degree of polymerization of 25000, i.e. A hydrolyzed polyacrylamide with a degree of polymerization outside the range required by the present invention was used.
A further Comparative Example 33B was conducted using the same method and the same ingredients but excluding the co-additive. The results are shown in the table.

[Table] The turbidity was measured on the wastewater from the degree of freedom (CSF) test, and the turbidity was expressed in terms of the "white water" characteristics obtained during the paper manufacturing process. The sheets of Examples 33 and 34 were good in all measured properties. Examples 33A and 34B have defects in formability and cannot be used. Comparative Example 33B has good formability, but low permeation, indicating poor aggregation on the fibers, and poor peeling resistance. Examples 33-38 Sheets were made as described in Examples 33 and 34. However, different latexes and different co-additives were used in two amounts as shown in the table. The latex used (latex P and Q) is 65% styrene.
and 35% butadiene, with a 70% core copolymer modified with 0.2% dodecanethiol, the core being 50% vinylbenzyl chloride, 35% butadiene and styrene.
It was capped with 30% of the 15% copolymer, which was later reacted with excess dimethyl sulfide. This reaction was started by removing excess dimethyl sulfide by vacuum distillation when the bound charge of the sulfonium group reached 0.19 milliequivalents per gram for latex P, and when the bound charge of latex Q reached 0.388 milliequivalents per gram. It was canceled. Co-additives as carboxyl groups per gram
It was a hydrolyzed polyacrylamide with an effective charge of 3.3 milliequivalents and a degree of polymerization of 4100. The results are shown in the table. Comparative Examples 35C and 37C Sheets were made as described in Examples 35 and 37, but without any co-additives. The results are also shown in Table XI.

TABLE Examples 35-38 illustrate the invention using different cationic bond charges than Examples 33 and 34, and also illustrate using widely different amounts of bond charges.

Claims (1)

[Scope of Claims] 1. (a) an aqueous slurry of negatively charged water-insoluble natural or synthetic fibers; Consisting of a nonionic organic polymer core surrounded by a shell of thin layers of water-insoluble copolymers with a bonded charge of pH-independent cationic groups in an amount of 0.07 to 0.6 milliequivalents per gram of copolymer. Ciel
Latex as a core structure particle and (c) having a degree of polymerization of 3000 or more, an effective charge of 0.3 to 8 milliequivalents per gram of polymer, and an acrylic carbon-carbon chain center axis, and in the presence of polyvalent metal ions at a pH of 4 to 7. mixing with a co-additive that is a water-soluble anionic polymer capable of retaining its water solubility to form an aqueous suspension; removing water from the aqueous suspension to form a tight mat; 1. A method for producing a high-strength fibrous nonwoven sheet-like article, comprising heating and drying mat; and wherein the copolymer particles of the latex described above are deformable at the operating temperature described above. 2. Claim 1 in which the solid standard amount of latex is 0.5 to 2000% based on the weight of the fibers.
The method described in section. 3 The amount of bonded charge in the latex per gram
A method according to claim 1, wherein the amount is greater than 0.1 milliequivalent. 4. The method of claim 1, wherein the co-additive is an acrylamide polymer. 5. The method of claim 4, wherein the anionic charge of the co-additive is imparted by a carboxyl group. 6 Co-additives 0.05 based on dry weight of fiber
2. A method according to claim 1, wherein the amount is between 160% and 160% by weight. 7 (a) Paper-grade fibers with anionic charge; (b) nonionic copolymer wrapped in a shell of thin layers of water-insoluble organic copolymer with bonded charge of cationic groups independent of pH. 5 to 2000%, calculated on a solids basis on a fiber weight basis, of shell-core structured particles with a coalesced core and a bonded charge of 0.15 to 0.6 milliequivalents per gram of polymer in the latex;
and (c) a water-soluble anionic acrylamide having a degree of polymerization of 3000 to 10000 and an effective charge of 0.3 to 8 milliequivalents per gram of polymer and capable of retaining its water solubility in the presence of polyvalent metal ions at pH 4 to 7. A high-strength fibrous nonwoven sheet-like article comprising a dry mixture containing 0.15 to 160%, based on the weight of fiber, of a co-additive that is a polymer. 8 The core is water-insoluble in the form of a homopolymer, containing 20 to 50% of an aliphatic conjugated diene, 20 to 80% of a monovinylidene aromatic compound, and 0 to 5% of a polar nonionic ethylenically unsaturated monomer. A high-strength fibrous nonwoven sheet-like article according to claim 7, comprising a copolymer with 0 to 25% of another ethylenically unsaturated nonionic monomer. 9 Effective charge amount of co-additive is 0.15 to 0.15 per gram
0.5 milliequivalent and co-additive polymerization degree is 5000
Claim 7 or 8 which is from 10,000 to 10,000
The high-strength fibrous nonwoven sheet-like article described in 1.