JPS6010138B2 - non-woven fabric - Google Patents

Description

[Detailed description of the invention] The present invention relates to a nonwoven fabric using a binder.

More details include vinyl acetate and ethylene and the general formula [R
, :day or CH3, R2:day or an alkyl group having 5 or less carbon atoms] in a weight ratio of 55 to 96.5
:40-3:5-0.5 using a persulfate as an initiator and a reaction product of a glyoxal compound and a salt of an alkali metal, ammonium or zinc sulfur oxide as a reducing agent. This invention relates to a nonwoven fabric using a binder obtained by emulsion copolymerization using a redox catalyst.

Vinyl acetate and ethylene and N- as a crosslinking agent
Binders obtained by emulsion copolymerization of methylol compounds or N-alkoxy compounds, or products such as nonwoven fabrics using binders are known, for example, French Patent No.
No. 56410 increases the solvent resistance of films produced from vinyl acetate copolymer emulsions;
In addition, in order to improve the high mechanical stability of the film, N-methylol compounds such as N-methylol acrylamide and N-methylol methacrylamide and N-alkoxy compounds such as methyl or butyl ether thereof are used as crosslinking agents at a ratio of 0.5 to vinyl acetate. ~1% by weight
It has been shown that the copolymer can be crosslinked at temperatures from room temperature to 180° C., preferably in the presence of a curing agent.

Also, U.S. Patent No. 3345318 and U.S. Patent No. 33808
No. 51 describes the emulsion polymerization of vinyl acetate-N-methylolacrylamide copolymer and the use of such an emulsion as a binder for nonwoven fabrics with excellent water resistance and solvent resistance. Therefore, nonwoven fabrics using such emulsions as binders have excellent water resistance, solvent resistance, and in addition, the properties inherent to vinyl acetate-ethylene copolymers, that is, light resistance, heat resistance, and embossing suitability. Disadvantages of poor heat resistance and light resistance of synthetic rubber latexes such as styrene-butadiene copolymers, acrylonitrile-butadiene copolymers, and methyl acrylate-butadiene copolymers, and acrylic copolymer emulsions. It has been widely used in this field because it has improved the disadvantages of poor heat resistance and embossing suitability when used as a binder.

On the other hand, the method for producing the binder used for such excellent nonwoven fabrics must be a method in which vinyl acetate, ethylene, and the crosslinking agent compound are uniformly copolymerized.

If the polymerization is carried out in a non-uniform manner, the cross-linking reaction will occur in the cross-linking agent compound, and a uniform cross-linking reaction will not occur during the cross-linking reaction. During processing, some of the bonds break off or dissolve. Therefore, in order to uniformly copolymerize pinyl acetate, ethylene, and a crosslinking agent, a method is used based on known polymerization techniques, such as adding a crosslinking agent compound continuously as the polymerization progresses, but the most important What is important is to maintain a constant polymerization reaction rate, ie, the desired polymerization temperature.

If the polymerization temperature cannot be kept constant, not only will it not be possible to obtain the desired uniform polymer, but the impregnating properties of the binder, which plays an important role in processability and workability when manufacturing nonwoven fabrics, will be affected. There also arises the problem of worsening the condition. However, methods for obtaining homogeneous copolymers are described in the aforementioned French Patent No. 156,410 and US Pat. No. 3,345,318;
As shown in the example of No. 3380851,
Emulsification using formaldehyde sodium phoxylate as a reducing agent that efficiently and stably decomposes the initiator at the desired polymerization temperature to generate radicals and promptly initiates polymerization. This is a method of copolymerization.

Nonwoven fabrics using binders produced by this method have excellent performance as described above, but since formaldehyde sodium oxylate is a compound containing formalin, nonwoven fabric products emit formalin.
Although they do not have a toxic odor, harmful formalin has been detected, and there is a problem in terms of safety when these products are used in applications where they come into direct contact with the skin. Therefore, an object of the present invention is to replace the conventional redox catalyst using formaldehyde sodium sulfoxylate as a reducing agent with a redox-based catalyst reducing agent that has an equivalent polymerization temperature controllability, and to The object of the present invention is to provide nonwoven fabrics and the like using a formalin-free binder in which a crosslinking agent compound is uniformly emulsion-copolymerized with formaldehyde sodium phosoxylate.

As a result of various studies in accordance with the purpose of the present invention, we found that by using a reaction product of a glyoxal compound and a salt of a reducing sulfur oxide as a reducing agent for a redox catalyst, it is possible to achieve the same result as when using conventional formaldehyde sodium phoxylate. The polymerization temperature can be controlled, a binder having a uniform copolymer can be obtained, and there is no formalin generated from formaldehyde sodium phoxylate in the binder, so nonwoven fabrics manufactured using such a binder can be obtained. It was found that this material has excellent water resistance, solvent resistance, etc., and has a small amount of formalin, which led to the present invention.

In order to achieve the object of the present invention, it is a necessary and sufficient condition to use a reaction product of a glyoxal compound and a salt of a reducible sulfur oxide as a reducing agent for a redox catalyst.
For example, if a 3-label reducing agent such as alkali metal or zinc salt, reducing sulfur oxide salt, or amine compound such as monoethanolamine or triethanolamine is used, polymerization itself may not be possible, or even if it is possible, the polymerization temperature may be too low. Controllability is poor, a binder having a uniform copolymer cannot be obtained, and the binder has poor impregnating properties.

In the present invention, reducing agents include glyoxal compounds such as glyoxal and methylglyoxal, sodium, potassium, and zinc salts of thiosulfuric acid, dithionite, and pyrosulfite, and sodium and potassium bisulfite salts. It is a reaction product of an alkali metal, ammonium or zinc with a reducing sulfur oxide salt, and can be easily obtained by reacting the two in an aqueous solution.

It is also advantageous to use such a reducing agent in combination with a heavy metal salt such as an iron salt or a copper salt as a so-called composite reducing agent. In addition, such a reducing agent can also be synthesized during emulsion copolymerization. For example, a glyoxal compound is made to exist in the emulsion dispersion before the start of polymerization, and an aqueous solution of a salt of a reducing sulfur oxide is added to the emulsion copolymerization. Alternatively, the glyoxal compound and the reducing sulfur oxide salt can be separately emulsified and dispersed. It is also possible to perform polymerization by adding it to a liquid and synthesizing the amount necessary for polymerization.

The amount of the reducing agent used in the present invention is not particularly limited, but is 0.25 to 3 times the amount of the commonly used oxidizing agent.

Examples of the oxidizing agent used in combination with such a reducing agent in the present invention include persulfates such as ammonium persulfate, ammonium persulfate, and sodium persulfate.

These are particularly preferably used because they also act as crosslinking aids in crosslinking reactions during the production of nonwoven fabrics and the like. In the present invention, the crosslinking agent that imparts excellent water resistance and solvent resistance is a compound represented by the general formula [A] [R, : day or CH3, R2: day or an alkyl group having 5 or less carbon atoms], such as N-methylol acrylamide, N-methylol methacrylamide, N-alkoxymethyl acrylamide
Examples include methylol compounds such as N-alkoxyethyl acrylamide and N-alkoxybutylacrylamide, and alkyl ethers thereof having 5 or less carbon atoms.

In addition, in the present invention, the polymerization amount of the compound of general formula [A] is limited to 0.5 to 5% by weight to ensure sufficient water resistance and solvent resistance in accordance with the final performance requirements of the nonwoven fabric using the binder. The purpose is to make it a nonwoven fabric, and the general formula [
This is because if the amount of the compound (A) is less than 0.5% by weight, a sufficient crosslinking effect cannot be obtained, and even if it is copolymerized with more than 5% by weight, a product exhibiting better performance cannot be obtained.

In the present invention, the ethylene content is limited to 3 to 4% by weight because the ethylene content is sufficient to change the texture from hard to soft depending on the final required performance of the nonwoven fabric using the binder. In addition, it is necessary to copolymerize at least 3% by weight of ethylene in order to provide sufficient water resistance strength, and even if ethylene is copolymerized by more than 4% by weight, the texture will be softer. This is due to the inability to obtain products with The emulsifier used in the emulsion copolymerization in the present invention is not particularly limited, and includes, for example, fully or partially saponified polyvinyl alcohol, fibrous derivatives such as methyl cellulose and hydroxyethyl cellulose, and ammonium salts of a-olefin-maleic anhydride. Various water-soluble polymers such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene polyoxypropylene block copolymer, various nonionic surfactants such as polyoxyethylene sorbitan fatty acid ester, lauryl sulfate, etc. Examples include anionic surfactants such as ester soda salt, zaalkyl succinate, and alkylbenzene sulfonate, which may be used alone or as a mixture.

Furthermore, additives such as pH adjusters and electrolytes can also be used by 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 qo, preferably 30 to 7
It is practical to maintain the desired polymerization temperature in the range of 0.2°.

The polymerization pressure is arbitrarily adjusted depending on the desired ethylene content of the polymer, and a polymerization pressure of 5 to 100k9 is used to obtain an ethylene content of 3 to 4% by weight. To produce a nonwoven fabric using the binder obtained according to the present invention, unbonded or prebonded nonwoven fabric compositions obtained by wet and dry methods are impregnated into such a binder or such a binder is sprayed. Alternatively, it may be adhered by a method such as printing, dried, and heat treated.

The processing equipment used here may be the most commonly used equipment, and there are no restrictions or changes. Also,
In addition to such binders, antifoaming agents, dispersion stabilizers, other known binders, etc. may be used in combination, if necessary. 100 to 18 to obtain the effect of crosslinking reaction
0CC, preferably 1-5 at a temperature of 130-15000
Heat treatment for 10 minutes is preferable, and if necessary, a known crosslinking aid such as ammonium sulfate or ammonium chloride may be used in combination. The nonwoven fabric produced in this way contains less formalin and has better water and solvent resistance than nonwoven fabrics conventionally produced using a binder obtained by emulsion polymerization using formaldehyde sodium phoxylate as a reducing agent. The same or better performance 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 modifiers, curing agents, knit dimensional stabilizers, and coating agents for waterproof fabrics, to obtain valuable products similar to 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.

{1} Reference Example, Binder Production Reference Example 1 The following items were charged into a pressure-resistant reactor equipped with a reaction temperature controller and a clearing machine.

32,000 t Water 365 t Hydroxyethyl cellulose with 25 moles of ethylene oxide added 800 Polyoxyethylene nonylphenol ether of Sunset LB17 800 Polyoxyethylene nonylphenol ether/res of Sunset LB14 Approximately 1 of these ingredients
Heat for an hour and completely dissolve.

The charge was cooled to about 30°C and then the following was added. 8250 ta Pynyl acetate 16 Poly acetic acid 20 ta Sodium acetate 0.8 ta FeS04 28802 8% glyoxalin sodium sulfite aqueous solution The reactor was purged with nitrogen and ethylene to remove oxygen.

The charge was then heated to 4500 ℃. During the heating period, ethylene was added to increase the pressure to 60 k9/hr. After the dissolution of ethylene into vinyl acetate monomer reached equilibrium, 8% ammonium persulfate aqueous solution was added at a rate of 1.4 k9/hr. After about 5 minutes, the initiation of polymerization was observed according to the reaction temperature, and the reaction temperature controller was adjusted so that the polymerization temperature was 5000.Next, two feeds were started, the first being vinyl acetate. 20,000 hours and the feed was at a constant rate for 4 hours.

The second was 2000 turquoise N-methylolacrylamide 5002 dissolved in water, and the feed was at a constant rate over a period of 5 hours. During this time, the cooling jacket temperature was set at 30 qo, and the charging of ammonium persulfate was switched to automatic adjustment, so that the set polymerization temperature of 50°C could be maintained. During this time, the polymerization pressure of ethylene was kept constant at 60k9/kg. Polymerization time9. Polymerization was terminated when the amount of unreacted vinyl acetate monomer decreased to 0.32%.

The obtained emulsion had a solid content of 50.5% by weight and a viscosity (
BL-60RPA, 2500) 92 specific ps, coarse particles that cannot be filtered with a 100 mesh wire mesh 13 Skin sedimentation rate 0.1 or less, ethylene content calculated from mass balance is 25% by weight, N-methylolacrylamide content is 1 .2% by weight.

For sedimentation, dilute the soil type with water to 1 t%, put 10' of it in a glass container with a 0.1M scale, centrifuge it for 30 minutes on the 300 side, and remove the sediment. read. If the amount of sediment is 0.2 or less, the emulsion is judged to be very stable. Reference Example 2 The following 100-capacity pressure-resistant reactor equipped with a reaction temperature controller and a flywheel was prepared.

340009 Water 365 Hydroxyethyl cellulose with 2.5 moles of ethylene oxide added 800 Yuhi LB17 polyoxyethylene noni'refeno'leatenole 800 Yuhi LB14 polyoxyethylene sononyl phenol ether These ingredients The mixture was heated for about 1 hour and completely melted.

The charge was cooled to about 30q0 before adding the following: 8250# Vinyl acetate 16# Acetic acid 20T Sodium acetate 0.8T FeS04 118T 40% glyoxal aqueous solution Purge the reactor with nitrogen and ethylene to remove oxygen.

The charge was then heated to 45 qo. During the heating period, 0.78 g of a 7% aqueous sodium metabisulfite solution was added. During this period, ethylene was added to increase the pressure to 60 k9/h, and after the dissolution of ethylene into vinyl acetate monomer reached equilibrium, 8
% weekly ammonium sulfate aqueous solution was added at a rate of 1.4 hours/hour. After about 5 minutes, the initiation of polymerization was observed based on the reaction temperature, and the reaction temperature controller was adjusted so that the polymerization temperature was 5,000. Next, there are two items that have started supplying, one is 7
% sodium metabisulfite in water, the feed was added at a constant rate of 0.17/hr over 8 hours.

The other was 20,000 g of vinyl acetate and 500 g of N-butoxyacrylamide, and the feed was carried out at a constant rate over a 5 hour period. Meanwhile, the cooling jacket temperature is set to 3.
0oo, the charging of ammonium persulfate was switched to automatic adjustment, and the set polymerization temperature of 50 qo could be constantly maintained.

During this period, ethylene was kept constant at a polymerization pressure of 60k9/kg. The polymerization was terminated when the unreacted vinyl acetate monomer decreased to 0.30% 9 hours after the start of the polymerization.

The obtained ethylene-vinyl acetate copolymer aqueous dispersion had a solid content of 51.4% by weight and a viscosity (BL-6 dish PM, 25qo
) 96 ratio ps, 16 rough particles that cannot be filtered with a 100 mesh wire mesh, sedimentation rate 0.1 The content is 1. % by weight.

Comparative Reference Example 1 Polymerization was carried out in the same manner as in Reference Example 1, except that formaldehyde sodium phoxylate was used as the reducing agent in an equimolar amount with glyoxal sodium bisulfite.

The polymerization time, reaction rate, and emulsion were also almost the same as in Example 1. Comparative Reference Example 2 The same procedure as in Reference Example 1 was carried out except that sodium bisulfite and glyoxal sodium sulfite were used in an equimolar amount as the reducing agent in Reference Example 1, but about 60 minutes after the start of addition of the ammonium persulfate aqueous solution ( After about 1.4 8% ammonium persulfate had been added by that time, a rapid exothermic reaction occurred and the ammonium persulfate feed was immediately stopped and cooling started, but the polymerization temperature rose to 75°C.

Even after that, the polymerization temperature could not be controlled automatically and was performed manually, but it was extremely difficult to control the polymerization temperature and a constant polymerization temperature could not be controlled. Further, the ethylene pressure was set to 65k9/cm to obtain the desired ethylene content. The final emulsion had a solid content of 49.8% by weight and a viscosity of BL-60RPM.
, 25qo) 46 ps, coarse particles that cannot be filtered with a 100 mesh wire mesh 37cm wind, sedimentation rate 0.8', ethylene content calculated from mass balance is 25. % by weight, N-
Methylol acrylamide was 1.2% by weight. '
2) The binders of Examples Reference Examples 1 and 2 and Comparative Reference Examples 1 and 2 were each impregnated into a 100% rayon nonwoven fabric wet cloth to an impregnation rate of 3% by weight. The cloth was dried and then heat treated at 130° C. for 5 minutes to prepare a nonwoven fabric for a pillow.

Table 1 shows the properties of these nonwoven fabrics. Table 1 (Note) 0 Amount of formalin detected; Formaldemode determined based on Ministry of Health and Welfare Ordinance No. 34 ○ Tensile strength is JISL-10
It was measured based on the tensile strength section of 85 Nonwoven Fabric Test Method.

The numerical value is the tensile strength in the transverse direction and is expressed as a KGSO value. K.G.S.
C value = Tensile strength [Kg No. Yanagi] Weight [9 No. 1] ○ Triclean resistance: Measured according to JISL-1085 tensile strength.

Claims (1)

[Claims] 1 Vinyl acetate and ethylene and a compound represented by the general formula ▲ Numerical formula, chemical formula, table, etc. ▼ [R_1:H or CH_3, R_2:H or an alkyl group having 5 or less carbon atoms] in a weight ratio So 5
A reaction product of a glyoxal compound and a salt of a reducing sulfur oxide of an alkali metal, ammonium or zinc is prepared using a persulfate as an initiator so as to have a composition of 5 to 96.5:40 to 3:5 to 0.5. A nonwoven fabric using a binder obtained by emulsion copolymerization using a redox catalyst as a reducing agent.