JPH0379466B2 - - Google Patents

Description

[Detailed description of the invention]

[1] Industrial Application Field The present invention relates to a nonwoven fabric using a binder.
More specifically, it relates to a nonwoven fabric using an improved binder mainly composed of vinyl acetate and ethylene. [2] Prior art Binders obtained by emulsion copolymerization of vinyl acetate, ethylene, and an N-methylol compound or N-alkoxy compound as a crosslinking agent, or products using a binder, are known, for example, as disclosed in French Patent No. No. 1564100 discloses the use of N-methylol acrylamide and N-methylol methacrylamide as crosslinking agents to increase the solvent resistance of films produced from vinyl acetate-ethylene copolymer emulsions and to improve the high mechanical stability of the films. Using 0.5 to 10% by weight of an N-methylol compound such as and its methyl or butyl ether and an N-alkoxy compound based on vinyl acetate, the copolymer is prepared at a temperature from room temperature to 180°C.
It has been shown that the crosslinking reaction is preferably carried out in the presence of a curing agent. Also, in U.S. Patent No. 3,345,318 and U.S. Pat. No. 3,380,851,
It is described that an N-methylolacrylamide copolymer is emulsion polymerized and that such an emulsion is used as a binder for nonwoven fabrics having excellent water resistance and solvent resistance. That is, the nonwoven fabric using such an emulsion as a binder has water resistance, solvent resistance, and vinyl acetate resistance as described in JP-A No. 52-55709.
Because ethylene copolymer has the inherent properties of excellent light resistance, heat resistance, and embossing suitability, it has been widely used in conventional styrene-butadiene copolymers, acrylonitrile-butadiene copolymers, and methyl acrylate-butadiene copolymers. It has been widely used in this field by improving the disadvantages of poor heat resistance and light resistance of synthetic rubber latex such as binders and poor heat resistance and embossing suitability of acrylic copolymer emulsion binders. It is being used. Note that nonwoven fabrics are inexpensive to manufacture.
Lack of unraveling properties. Woven fabrics have many features such as greater water absorption, porosity, and elasticity, and are currently used in towels, diapers, wiping cloths, sheets, sanitary napkins, masks, and various hospital gowns. Covers, disposable towels, tablecloths, aprons, interlining,
It is used in large quantities in end applications such as various filters. There are many methods for producing nonwoven fabrics, such as adhesive type, needle punch type, spunlace type, stitch bond type, and spun bond type, but the present invention mainly belongs to the adhesive type. The adhesive type is a method in which a loosely gathered fiber mass (wep) is integrated with a binder, and it is manufactured by applying a binder to the loosely gathered fiber mass (wep) by impregnation printing, spraying, or other methods, and then drying it. It is a method. The fibers are natural cellulose,
It may be made of polyester, polyamide, polyacrylic, rayon, wool, jute, or a mixture thereof. The loosely gathered fiber mass may be created by carding, garnetting, airlaying, papermaking or other known operations. [3] Problems to be solved As mentioned above, by copolymerizing N-methylol compounds such as N-methylolacrylamide, N-methylolacrylamide, and their N-alkoxy compounds with vinyl acetate and ethylene as crosslinking agents, water resistance can be improved. However, in many end uses, further improvements in water resistance and solvent resistance are required. On the other hand, non-woven fabric products emit formalin and are not known to have a toxic odor, but toxic formalin has been detected and there are safety concerns when these products are used in applications where they come into direct contact with the skin. There was a problem that I didn't like it. That is, there is a need to further reduce formalin (residual free formaldehyde, hereinafter abbreviated as "FF") in nonwoven fabrics, and at the same time to improve water resistance and solvent resistance. Furthermore, in order to improve water resistance and solvent resistance, it is natural to increase the crosslinking density of the binder, and for this purpose monomers involved in crosslinking such as N-methylol compounds and N-alkoxy compounds Although it is necessary to increase the content of these monomers, increasing the content of these monomers inevitably increases FF, and it has been difficult with conventional techniques to simultaneously satisfy the requirements of improving water resistance and solvent resistance and reducing FF. The present invention has made this possible. [4] Means for solving the problems The present invention provides (A) vinyl acetate and ethylene and the general formula (R ₁ represents H or CH ₃ , and R ₂ represents H or an alkyl group having 5 or less carbon atoms.) The monomer shown in the following is an essential component, and the weight ratio thereof is 55 to 96.5:40 to 3:5 to 0.5, (B) a formaldehyde-free nitrogen-containing glyoxal resin, and (C) a metal salt catalyst, the (C) metal salt catalyst being magnesium chloride, and a copolymer emulsion comprising: Use of a binder relating to a nonwoven fabric characterized in that the use ratio of the emulsion to formaldehyde-free nitrogen-containing glyoxal resin and metal salt catalyst is 100:1 to 10:0.05 to 4 in terms of solid weight ratio. This makes it possible to simultaneously improve water resistance and solvent resistance and reduce FF. The copolymer emulsion [A] will be explained in detail. The monomer represented by general formula (1) is, for example, N-
Methylol (meth)acrylamide (refers to both N-methylol acrylamide and N-methylol methacrylamide; the same applies hereinafter), N-
Methoxymethyl (meth)acrylamide, N-
Ethoxymethyl (meth)acrylamide, N-
Butoxymethyl (meth)acrylamide and the like can be mentioned. Note that the monomer represented by formula (1) does not need to be one type, and may be a mixture of two or more types. Moreover, in the present invention, the copolymerization amount of the compound of general formula (1) is limited to 0.5 to 5 in terms of weight ratio.
This is to provide sufficient water resistance and solvent resistance in accordance with the final required performance of the nonwoven fabric using a binder, and if the amount of the compound of general formula (1) is less than 0.5, a sufficient crosslinking effect cannot be obtained, and This is because a product exhibiting better performance cannot be obtained even if more than 5 is copolymerized. In the present invention, the amount of ethylene copolymerized is limited to 3 to 40% by weight because the ethylene copolymerization amount is sufficient to appropriately change the texture from hard texture to soft texture depending on the final required performance of the nonwoven fabric using the binder. In addition, in order to provide sufficient water resistance strength, it is necessary to copolymerize with ethylene at a weight ratio of at least 3 or more, and even if ethylene is copolymerized with a weight ratio of 40 or more, a more flexible texture can be obtained. This is due to the inability to obtain products that have Note that the copolymer emulsion [A] does not need to consist only of vinyl acetate, ethylene, and the monomer represented by the general formula (1), but may also include methyl (meth)acrylate, butyl (meth)acrylate, (meth)
Various (meth)acrylic esters such as octyl acrylate and glycidyl (meth)acrylate,
Various unsaturated acids such as acrylic acid, itaconic acid, maleic acid, (meth)acrylamide, vinylsulfonic acid (or its salt), 2-hydroxyethyl (meth)acrylamide, vinyl chloride, vinylidene chloride, styrene, butadiene, acrylonitrile, It may also be one further copolymerized with diallyl esters such as maleic acid, adipic acid, and phthalic acid, triallyl esters of benzenetricarboxylic acid, multipolymerizable monomers such as triallyl isocyanurate, and the like. There are no particular restrictions on the method for producing the copolymer emulsion [A]. Examples of emulsifiers include completely or partially saponified polyvinyl alcohol, fibrous derivatives such as methylcellulose and hydroxyethylcellulose, various water-soluble polymers such as ammonium salts of α-olefin-maleic anhydride, holoxyethylene alkyl ether, and polyoxyethylene alkyl. Various nonionic surfactants such as phenyl ether, polyoxyethylene polyoxypropylene block copolymer, polyoxyethylene sorbitan fatty acid ester, anionic surfactants such as lauryl sulfate ester sodium salt, dialkyl succinate, alkylbenzene sulfonate, etc. These are used alone or as a mixture. As the polymerization initiator, a redox initiator is preferable. Examples of the oxidizing agent include ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, and various organic peroxides. Note that persulfates are particularly preferably used because they and their decomposition products also act as crosslinking catalysts. Examples of the reducing agent include formaldehyde sodium sulfoxylate, a reaction product of glyoxal and a salt of a reducing sulfur oxide, and the like. Additionally, additives such as PH regulators and electrolytes can also be used using known emulsion polymerization techniques. There are no particular restrictions on polymerization conditions such as polymerization pressure and polymerization temperature, but generally the polymerization temperature is in the range of 0 to 100°C, preferably
It is practical to maintain it in the range of 30-80°C. In addition, the polymerization pressure is arbitrarily adjusted depending on the amount of ethylene in the desired copolymer.
A polymerization pressure of Kg/cm ² is used. The solid content concentration in the emulsion can be adjusted by adjusting the amount of monomers to be copolymerized and water, but a solid content concentration of about 40 to 60% by weight is suitable from the viewpoint of industrial use. The formaldehyde-free nitrogen-containing glyoxal resin [B] will be described in detail. The nitrogen-containing glyoxal resin is 4,5
-dihydroxy-2-imidazolidinone, 1-
Urea containing methyl-4,5-dihydroxy-2-imidazolidinone, 1,3-dimethyl-4,5-dihydroxy-2-imidazolidinone, etc.
N-monomethylurea, reaction product of N,N-dimethylurea and glyoxal, ethyleneurea, propyleneurea, uron, 4,5-dihydroxy-2-imidazolidinone, tetrahydro-5-(2-hydroxyethyl)- 1,3,5-
Triazin-2-one, reaction product of 5-methyl-2-pyrimidinone and glyoxal and its alkylated product or polyhydric alcohol modified product, 1,3-bis(2-hydroxyethyl)-
Compounds with an amide group structure such as 4,5-dihydroxy-2-imidazolidinone, formaldehyde, N-methylformaldehyde, acetamide, methylenebisformaldehyde, ethylenebisformaldehyde, methyl carbamate, isopropyl carbamate, hydroxyethyl carbamate, acrylamide, pyrrolidone, etc. and glyoxal, and alkylated products or polyhydric alcohol-modified products thereof. The glyoxal resin mentioned here is a compound collectively referred to as a non-formaldehyde crosslinking agent in the field of fiber processing resins, but preferably has 1,3-dimethyl-4,5-dihydroxy-2-imidazolidinone as its main component. Glyoxal resin, the most practical. The metal salt catalyst [C] will be explained in detail. The metal salt is used for fiber processing (wrinkle-proofing, shrink-proofing,
It refers to a metal salt catalyst that is used or proposed for use in permanent press processing, W&W processing, etc.), and in the present invention, it is characterized by low coloring of cellulose fibers, high crosslinking catalytic effect, and high safety. Magnesium chloride is used because of its balance of various properties. Note that the addition and use of a Brnsted acid, regardless of whether it is an inorganic acid or an organic acid, to magnesium chloride is well known as a strong catalyst (Hot Catalyst, Activated Catalyst) system. Naturally, this strong catalyst system is also included. However, the other component constituting the present invention, that is, the copolymer emulsion [A], contains persulfates, organic peroxides, formaldehyde sodium sulfoxylate, polymerization products of glyoxal and reducible sulfur oxides, etc. Bronsted acids are generally included in initiators, surfactants such as sodium lauryl sulfate and alkylbenzene sulfonates, PH regulators, copolymerized monomers such as acrylic acid and maleic acid, etc.
In copolymer emulsions containing the required amount of Bronsted acid, metal salt catalysts are
No need to add Bronsted acid to make it a strong catalyst system. In addition, the powerful catalyst system
Bronsted acids include citric acid, maleic acid,
Examples include methanesulfonic acid, phosphoric acid, primary ammonium phosphate, sulfuric acid, hydrochloric acid, and aluminum dichlorohydroxide, but there are no particular limitations. The ratio of the copolymer emulsion [A], the glyoxal resin [B], and the metal salt catalyst [C] is [A]:[B]:[C]=100:1 to 10:0.05 to 4.
(solid content weight ratio). If [B] is less than 1 part by weight with respect to 100 parts by weight of [A], it will be difficult to achieve the object of the present invention, and if it exceeds 10 parts by weight, the objectives of the invention, namely water resistance and solvent resistance, will not be achieved. sex,
The effect of improving FF has reached a plateau, and it is wasted [B]
Only a large amount of glyoxal resin is used. Furthermore, with regard to [C], if it is less than 0.05 parts by weight per 100 parts by weight of [A], it will be difficult to achieve the object of the present invention, and if it exceeds 4 parts by weight, water resistance and solvent resistance will be impaired. , the effect of improving FF tends to reach a plateau or decline. The copolymer emulsion [A], the glyoxal resin [B], and the metal salt catalyst [C] have been explained above, but the binder for the nonwoven fabric includes [A],
In addition to [B] and [C], known foaming agents, antifoaming agents, dispersion stabilizers, wetting agents, thickeners, etc. may be used as necessary, and known emulsions and Latex may also be used. In order to produce a nonwoven fabric using the binder obtained according to the present invention, an unbonded or prebonded web obtained by wet and dry methods is impregnated into such a binder, or may be applied by spraying or printing, followed by drying and heat treatment.
The processing equipment used here may be the most commonly used equipment, and there are no restrictions or changes. In order to obtain the effect of crosslinking reaction, heat treatment at a temperature of 100 to 180°C, preferably 120 to 150°C for 1 to 20 minutes is appropriate. In this way, a nonwoven fabric with low FF and high water resistance and solvent resistance can be obtained. It should be noted that the present invention can also be applied to textile processing fields other than non-woven fabrics, such as texture control agents, curing agents, dimensional stabilizers for knitted fabrics, coating agents for waterproof fabrics, etc., to obtain valuable products similar to those for non-woven fabrics. The present invention will be explained in more detail below with reference to Reference Examples and Examples, but the present invention is not limited thereto. [5] Reference Examples and Example 1 Reference Example 1 (Production of copolymer emulsion) The following items were charged into a 100 pressure-resistant reactor equipped with a reaction temperature controller and a stirrer. 32000g water 365g hydroxyethyl cellulose with 2.5 moles of ethylene oxide added 800g HLB17 polyoxyethylene nonylphenol ether 800g HLB14 polyoxyethylene nonylphenol ether These materials were heated and stirred for 1 hour to completely dissolve. The charge was cooled to approximately 30°C before the following were added. 8250 g Vinyl acetate 16 g Acetic acid 20 g Sodium acetate 0.8 g FeSO ₄ 2880 g 8% glyoxal-sodium heavy zinc aqueous solution The reactor was purged with nitrogen and ethylene to remove oxygen, and the charge was then heated to 45°C. During the heating period, add ethylene to make the pressure 60Kg/cm ² and reduce the temperature to 8%.
When the ammonium persulfate aqueous solution was added and polymerization started, the following two things were started to be fed. The first was 20,000 g of vinyl acetate, and the feed was at a constant rate over 4 hours. The second one is water
550 g of N-methylolacrylamide was dissolved in 2000 g, and the feed was carried out at a constant rate over a period of 5 hours. During this time, ethylene has a polymerization pressure of 60Kg/cm ²
was held constant. Polymerization was terminated when unreacted vinyl acetate monomer decreased to 0.32% after a polymerization time of 9.5 hours. The obtained emulsion has a solid content
The ethylene content calculated from the mass balance was 25% by weight, and the N-methylolacrylamide content was 13% by weight. The resulting emulsion is called . Reference Example 2 (Production of copolymer emulsion) Polymerization was carried out in the same manner as in Reference Example 1, except that equimolar amounts of sodium formaldehyde sulfoxylate were used in place of glyoxal sodium bizinc sulfate. The solid content of the emulsion obtained was 50% by weight, and the ethylene content calculated from the mass balance was
25% by weight, and the N-methylolacrylamide content was 1.3% by weight. The resulting emulsion is called . Reference Example 3 N-methylolacrylamide of Reference Example 1
20,000 g of vinyl acetate, which is supplied after polymerization has started, is supplied after adding and dissolving 820 g of N-n-butoxymethylacrylamide, and ethylene is the same as the reference example (1) except that the polymerization pressure is 45 Kg/ ^cm2 . ). The solid content of the obtained emulsion was 50% by weight, the ethylene content calculated from mass balance was 17% by weight, the N-methylolacrylamide content was 1.0% by weight, and the N-n-butoxymethylacrylamide content was 2.0%. It was in weight%. The resulting emulsion is called . Reference Example 4 (Production of copolymer emulsion) Vinyl acetate supplied after polymerization has started
The same procedure as in Reference Example 2 was carried out except that 2,825 g of the 20,000 g was replaced with 2-ethylhexyl acrylate. The solid content of the obtained emulsion was 50% by weight, the ethylene content calculated from the mass balance was 25% by weight, the N-methylolacrylamide content was 1.3% by weight, and the 2-ethylhexyl acrylate content was 7% by weight. It was hot. The resulting emulsion is called . Reference Example 5 (Manufacture of nitrogen-containing glyoxal resin) 290 parts (2 mol) of a 40% glyoxal aqueous solution was adjusted to pH 6.5 with sodium carbonate. 176 parts (2 mol) of ethylene urea was added and the temperature was raised to 50±5°C.
The mixture was heated to a pH of approx.
Stirred at that temperature for an hour. 2 hours later methanol
200 parts (6.25 moles) were added and the pH was adjusted to about 3.0 with concentrated sulfuric acid. To complete the methylation reaction, the resin solution was refluxed for 3 hours and cooled to 30°C, then the pH was brought to about 7.0 with a 25% aqueous solution of caustic soda.
The solids content was adjusted to 50% by diluting with a small amount of water. The obtained glyoxal resin is called. Reference Example 6 (Production of nitrogen-containing glyoxal resin) 363 parts (2.5 mol) of 40% glyoxal aqueous solution
The pH was made approximately neutral with a 25% caustic soda aqueous solution. Add 242 parts (2.75 mol) of dimethyl urea to 50±
The temperature was raised to 5°C. The mixture was stirred at this temperature for about 20 hours while keeping the pH between 6 and 7. Then
The mixture was cooled to 30°C, the pH was adjusted to about 5 with sulfuric acid, and the solid content was adjusted to 40% by diluting with water. The obtained glyoxal resin is called. 2 Examples 1 to 14 and Comparative Examples 1 to 20 Emulsions produced in Reference Examples...
and glyoxal resin, and magnesium chloride as a crosslinking catalyst, various formulations were prepared so as to have the solid content ratios shown in Table 1, and these were used as impregnating liquids. Each 100% rayon nonwoven fabric web was impregnated with this impregnating liquid to an impregnation rate of 30% by weight.
After impregnation, dry at 130℃ for 1.5 minutes, then dry at 130℃,
Heat treatment was performed for 10 minutes to produce a nonwoven fabric with a basis weight of 45 g/m ³ . The properties of these nonwoven fabrics are also listed in Table 1. The test conditions are as follows. All tensile strengths were measured based on the tensile strength test method of JISL-1085 nonwoven fabric test method. (1) Dry tensile strength: Measured under standard conditions at 20℃ and 65%RH. (2) Water resistance: Tensile strength after immersion in water at 20℃ for 30 minutes. (3) Solvent resistance: Tensile strength after immersion in methyl ethyl ketone or gasoline at 20°C for 30 minutes. (4) FF: Free formalin in the impregnated paper was measured according to JIS L-1041 and JIS L-1096 (acetylacetone method, sample 2.5 g). The performance evaluation results of the nonwoven fabrics are shown in Table 1. In each emulsion, water resistance, solvent resistance, and FF were improved only by adding formaldehyde-free nitrogen-containing glyoxal resin and metal salt catalyst, and using the three together. It is clear that improvements have been made at the same time. Examples 15-16 and Comparative Examples 21-26 100 parts by weight (solid content) of the emulsion obtained in Reference Example 1, 2.5 parts by weight of the glyoxal resin obtained in Reference Example (5)
Various formulations containing crosslinking catalysts shown in weight parts (solid content) and Table 2 were prepared, and various tests shown in Table 2 were conducted on the formulations. Test methods other than yellowing were conducted according to Examples 1 to 14 and Comparative Examples 1 to 20. The yellowing degree test was conducted as follows. That is, the nonwoven fabric coated with each formulation was held for 15 to 60 minutes during hot air drying maintained at 150°C, and the degree of yellowing at that time was measured using a Hunter whiteness meter (manufactured by Murakami Color Research Institute). It was measured. The conditions and results are shown in Table 2.

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[Table] [6] Effects of the invention As described above, the present invention provides a nonwoven fabric with improved water resistance, solvent resistance, and FF at the same time.

Claims (1)

[Claims] 1 (A) Vinyl acetate and ethylene and general formula (R ₁ represents H or CH ₃ , and R ₂ represents H or an alkyl group having 5 or less carbon atoms.) The monomer represented by the following is an essential component, and the polymerization ratio is 55-96.5:40-3:5- 0.5, (B) a formaldehyde-free nitrogen-containing glyoxal resin, and (C) a metal salt catalyst, the (C) metal salt catalyst being magnesium chloride, and a copolymer emulsion comprising: A nonwoven fabric characterized by using a binder in which the ratio of emulsion to formaldehyde-free nitrogen-containing glyoxal resin and metal salt catalyst is 100:1 to 10:0.05 to 4 in solid weight ratio. 2. The nonwoven fabric according to claim 1, wherein the formaldehyde-free nitrogen-containing glyoxal resin has 1,3-dimethyl-4,5-dihydroxy-2-imidazolidinone as a main component.