JPS5838456B2 - Porous sheet with waterproofness and moisture permeability and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a porous sheet having both excellent waterproofness and moisture permeability.

More specifically, the present invention relates to a method for producing a flexible porous sheet that is made of a microporous coagulated layer of polyurethane elastomer and has excellent waterproofness and moisture permeability.

Various proposals have been made regarding methods for producing moisture-proof or air-permeable polymer films, but in particular, a method is proposed in which a dimethylformamide solution of polyurethane elastomer is applied or impregnated onto a fiber base material, and then the base material is coagulated. The so-called wet coagulation method, in which the polyurethane elastomer is coagulated and deposited by immersion in a bath, is a preferred manufacturing method because it forms a porous coagulated layer containing many fine pores and provides moisture permeability or air permeability.

However, although this method can easily impart moisture permeability or air permeability, it is extremely difficult to impart waterproofness.

That is, in order to impart waterproofness to such a porous coagulated layer, it is necessary to post-treat the coagulated layer with a waterproofing agent, such as a water repellent, but in normal waterproofing methods, the treatment agent It is difficult to provide waterproofness to the surface of the pores inherent in the coagulated layer because it is difficult to penetrate into the internal voids, and even if it penetrates into the interior, it will migrate to the surface of the layer due to continued heat treatment. As a result of imparting waterproofness only to the surface of the coagulated layer, there are drawbacks such as, although the surface has water repellency, water leakage through the porous coagulated layer is not achieved and durability is insufficient.

Various other methods have been proposed for producing polymer coatings that are both waterproof and moisture permeable or breathable, but those that have excellent waterproof properties have poor moisture permeability or air permeability.
On the other hand, polymer films that have excellent moisture permeability or air permeability are poor in waterproof properties, and there is still no method for producing polymer films that have contradictory properties.

The present inventors improved the above-mentioned drawbacks and investigated a method for manufacturing a polymer film that is durable and has both excellent waterproofness and moisture permeability. As a result, a porous film was produced by a wet coagulation method using a polyurethane elastomer solution. By adding a fatty acid metal complex compound to the elastomer solution when forming a solidified layer, it is possible to impart waterproofness to the surface of the numerous micropores inherent in the formed solidified layer, and thus The present invention was achieved by discovering that a durable coating film having excellent waterproofness and moisture permeability can be easily produced.

That is, the present invention consists of a fiber base material having a porous coagulated coating mainly composed of polyurethane elastomer, and the coating has the following general formula (A) (however, the above general formula (A
), R is a hydrocarbon group having 8 or more carbon atoms, M is Cr or AI, X and Y
represents C1 or OH.

Note that X and Y may be the same or different) A porous sheet having waterproofness and moisture permeability in the presence of a metal complex compound of fatty acids represented by When manufacturing a porous sheet by a wet coagulation method in which a solution is applied as a coating liquid to a fiber substrate, the substrate is then introduced into a coagulation bath to coagulate the polyurethane elastomer, and then washed with water and dried, the coating liquid The present invention relates to a method for producing a porous sheet having waterproofness and moisture permeability, which is obtained by adding a metal complex compound of a fatty acid represented by the above general formula (A) therein.

In the present invention, the fatty acid metal complex compound added to the coating solution is represented by the general formula (A) above.
Representative examples of ner-type metal complex salts include stearic acid chromic chloride and stearic acid aluminum chloride.

It is known that the metal complex compound is water-soluble and highly reactive, and an aqueous solution of the compound can be used as a water repellent for cellulose fibers, but on the other hand, it can be used as a water repellent for synthetic fibers, synthetic resins, etc. It is also widely known that it is ineffective.

Therefore, when the metal complex compound is added and blended into the polyurethane coating liquid as in the present invention, when the coating liquid is immersed in water in a wet coagulation method, the metal complex compound is dissolved at the same time as the solvent in the coating liquid is eluted into the coagulation bath. Because of the water solubility of the compound itself, it is predicted that most of it will flow out into the coagulation bath and the water repellent effect on the coagulated layer will be lost, and this has not been done in the past.

Further, the reactivity of the metal complex compound with polyurethane elastomers has not been studied at all because the reaction mechanism is different from that with cellulose fibers.

However, surprisingly, a porous sheet manufactured using a wet coagulation method using a polyurethane elastomer solution containing a metal complex compound of higher fatty acids as a coating solution has excellent durability and waterproof properties. It was found that it also has moisture permeability.

Although there was a concern that the metal complex compound would leak into the coagulation bath because it is water-soluble itself, it was able to provide a durable and excellent waterproofing effect, but its mechanism of action has not been investigated. Although it may not be obvious, a large number of urethane bonds and urea bonds constituting the polyurethane elastomer form coordination bonds with the metal of the metal complex compound, or similar strong bonds, resulting in the formation of a large number of fine pores inherent in the porous solidified layer. It is presumed that it exhibits the function of imparting durable and excellent waterproofness to the surface.

Further, the metal complex compound has a pore-regulating effect and also has the effect of narrowing the diameter of the pores produced.

Note that there is no particular restriction on the amount of the metal complex compound used, but
It is desirable to add it to the coating solution in an amount of 3 to 10 parts by weight.

If the weight is less than 3 weight φ, a sufficient waterproofing effect cannot be obtained, while if the weight is more than 10 weight, the diameter of the pores formed will be significantly increased, which is not preferable.

The polyurethane elastomer used in the present invention may be any commonly used polyester polyurethane elastomer or polyether polyurethane elastomer.

The amount of the elastomer used is 8 to 25% in the coating solution.
It is generally used within the weight range.

Examples of the polar organic solvent used in the present invention include dimethylformamide, dimethylacetamide, dimethylsulfoxide, and tetrahydrofuran, with dimethylformamide being the most common.

Note that commonly used light resistance improvers, extenders, fillers, colorants, coagulation regulators, and the like may be added to the above-mentioned solvent solution of the polyurethane elastomer.

Further, as the coagulation bath of the present invention, a bath that is a non-solvent for the polyurethane elastomer and is miscible with the solvent for the elastomer can be used, but water is the most economical.

However, the coagulation bath may contain a small amount of polyurethane elastomer solvent.

As the fiber base material, woven fabrics, knitted fabrics, nonwoven fabrics, etc. made of natural fibers, synthetic fibers, etc. can be used.

The various means used for wet coagulation of polyurethane elastomer solutions are very widely applicable in the practice of this invention.

The present invention will be explained in further detail by way of Examples below.

Example 1 15 parts of polyester polyurethane elastomer, 8 parts of stearic acid chromic chloride, and 5 parts of silica gel
A coating liquid prepared by dissolving or dispersing 1 part in 72 parts of dimethylformamide was coated on nylon taffeta that had been softened and softened using a reverse roll coater for about 20 parts.
0 g/m" was applied, immediately introduced into a water bath containing 1% dimethylformamide, gelled by immersion in water at 20°C for 5 minutes, and then washed with hot water at 80°C for 30 minutes.
A porous sheet with a flexible texture can be obtained by drying with hot air at 0'C and then heat-treating at 140C for 5 minutes.

This sheet is immersed in a silicone emulsion with a concentration of 3, and after being squeezed uniformly with a mangle to a squeezing rate of well over 50, it is heat-treated at 150'C for 30 seconds using a conventional heat setter.

The obtained product has a water resistance of 1,600 m (H20/d), a water repellency of 100, and a moisture permeability of 5,300! 9/m/24h
It has excellent waterproofness and moisture permeability as rs, and also has good washing resistance and dry cleaning resistance, making it suitable for uses such as ski anoraks and raincoats.

In addition, in the above-mentioned Example 1, a liquid mixture consisting of 15 parts of polyester polyurethane elastomer, 5 parts of pore control agent, and 80 parts of dimethylformamide was used as the coating liquid, and when the same treatment as in Example 1 was performed, the following was obtained. The water resistance of the product is 200 IIH20, and the water repellency is 90 to 100. Moisture permeability 11009 /ra'/ 24 hrs and waterproof (
In particular, it has insufficient water resistance) and moisture permeability, making it unsuitable for use as waterproof clothing.

Example 2 Polyester polyurethane elastomer - 17 parts Aluminum stearate chloride 5 parts of silicone water repellent and 3 parts of inorganic filler are dissolved or dispersed in 72 parts of dimethylformamide to prepare a coating liquid.

This coating solution was applied onto the polyester film using a knife over roll coater to a thickness of about 1509/rrj, then introduced into a dimethylformamide aqueous solution with a concentration of 10%, immersed at 30°C for 5 minutes, and then heated at 120°C. By drying with hot air and heat-treating at 140° C. for 5 minutes, a porous sheet with a soft texture can be obtained.

This sheet is immersed in an aqueous dispersion of a fluorine-based water repellent at a concentration of 5%, uniformly squeezed with a mangle to a squeezing rate of 50%, and then heat-treated at 150° C. for 30 seconds using a heat setter.

The resulting product has a water resistance of 2200 mmH2O/cr/l
.

Water repellency 1001 Moisture permeability 51009/m”/24 hr
It has excellent waterproofness and moisture permeability, and these physical properties show almost no deterioration even after washing 5 times in accordance with JIS L-0844 (A-2), making it suitable for various types of waterproofing. Suitable for clothing.

Claims (1)

[Scope of Claims] 1. A fiber base material having a porous coagulated coating mainly composed of polyurethane elastomer, and in which the coating has a general formula (wherein R is a hydrocarbon group having 8 or more carbon atoms, M is C
r or A3X and Y represent CI or OH. A porous sheet having waterproofness and moisture permeability, characterized by the presence of a metal complex compound of a fatty acid represented by (X and Y may be the same or different). 2. Porous is formed by a wet coagulation method in which a polar organic solvent solution mainly containing polyurethane elastomer is applied as a coating liquid to a fiber base material, the base material is then introduced into a coagulation bath to coagulate the polyurethane elastomer, and then washed with water and dried. When manufacturing a quality sheet, the general formula (wherein, R is a hydrocarbon group having 8 or more carbon atoms, and M is C
r or A1, X and Y represent CI or OH. Note that X and Y may be the same or different.