JPS599574B2 - Manufacturing method for flexible sheet materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel method for manufacturing a structure having many fine communicating pores, and in particular to a flexible structure made of an elastic polymer material having excellent air permeability, moisture permeability, and good mechanical properties. The present invention relates to a method for easily manufacturing a sheet-like product.

In recent years, a number of methods have been proposed to produce synthetic alternative materials that have the excellent properties of natural leather, but the so-called wet method involves impregnating and coating a substrate with a polymer solution and coagulating it in a coagulation bath containing a poor solvent. The method is widely adopted industrially.

However, in the conventional wet method5, a polymer solution containing expensive good solvents such as dimethylformamide, dimethylsulfoxide, and tetrahydrofuran is used, and the removal and recovery of this solvent is extremely disadvantageous industrially. . On the other hand, as a method that does not use a coagulation bath, for example,
No. 5-36435 proposes a method in which a polymer-water-solvent slurry is formed, a substrate is coated or impregnated with the slurry, and then the solvent is evaporated while suppressing water evaporation, and then the water is evaporated. . However, this method does not avoid the drawbacks of the conventional wet method in that a solvent is used. The present inventors have conducted various studies on the production of microporous sheet products that can overcome these drawbacks, and as a result, we have added surfactant to an emulsion of elastomer polymer in excess of the minimum amount necessary to prevent coagulation of the resin. and further add eluted and removable solid fine particles to 20 to coagulate the emulsion suspension liquid into a film or sheet, or impregnate and/or apply the liquid to a fiber mat, etc., and then heat treat it. It has been discovered that a molded article having a microporous structure can be easily and effectively obtained by fixing the polymeric elastic body using the method described above and then dissolving and removing the solid fine particles and the surfactant. On the other hand, in conventional leather-like sheet materials, in order to manufacture ones with a particularly flexible texture, when the fibers and the binder are made of a polymeric elastic material, it is necessary to prevent both components from coming into close contact with each other. It is known that good results can be obtained when the structure is made, and in order to obtain this condition, for example, a fiber mat pretreated with paraffin wax, stearyl alcohol, etc. is impregnated with a polymer solution for 30 minutes, and wet coagulation is performed. A method is known in which the pretreatment substance is subsequently dissolved and removed. However, this method requires a step of pretreatment and a step of removing the pretreated material. Not only is the operation complicated because it requires a long distance, but
Since the pretreated material is eluted into the coagulation bath, the management of the coagulation bath becomes complicated, which is extremely disadvantageous industrially.

The present inventors investigated a method of obtaining a similar effect without using such means, and found that the fine particles contained in a sufficient amount of surfactant to prevent salting out of the emulsion due to the addition of solid fine particles. When the fiber mat is impregnated with the polymer elastomer emulsion, the synergistic effect of the surfactant and the solid particles creates a structure similar to that obtained by pretreatment in the wet method, where there is extremely little adhesion between the resin and the fibers. It was also found that a flexible sheet-like product with good elasticity could be obtained. The present invention will be explained in more detail. As the polymeric elastomer to be dispersed in the emulsion used in the present invention, resin components of emulsions conventionally used for nonwoven fabrics and the like can be conveniently used. Examples of the resin component include polyurethane, acrylic elastomer, acrylonitrile-butadiene copolymer, natural rubber, and other synthetic rubbers, and mixtures thereof or mixtures mainly composed of these rubbers can also be used. The concentration of the elastomer in these emulsions is usually in the range of 10 to 50 weight percent. On the other hand, as a dispersion medium for such an emulsion, any medium can be used as long as it does not act as a solvent for the fiber mat; however, from an industrial standpoint, water is particularly excellent. Furthermore, as the surfactant to be present in the emulsion used in the present invention, nonionic and anionic surfactants are preferably used, and particularly preferred are nonionic and water-soluble polyethylene glycol type surfactants with an HLB value. High ones, such as HLB12~
Polyethylene glycols having a strong hydrophilicity of about 19% are suitable, and examples of such polyethylene glycol types include polyoxyethylene alkyl phenol ether, polyoxyethylene 3-ethylene alkyl ether, polyoxyethylene sorbitan fatty acid ester, and polyoxyethylene fatty acid ester.

The amount of surfactant added is 1 to 20% by weight based on the solid content of the polymer elastomer. is usually employed, but it is selected as appropriate in relation to the viscosity of the emulsion, the suspension, and the amount of solid fine particles added, and the amount used is such that the emulsion does not break due to the salting out effect of the solid fine particles added to the emulsion. . Therefore, in the present invention, a larger amount of surfactant is used than is present in a conventional resin emulsion. Furthermore, in the present invention, the solid fine particles added to the emulsion do not necessarily have to be insoluble in the emulsion solution, but may have relatively low solubility and substantially form a suspension, and can be heat-treated. Any material that can be easily removed by elution with a solvent such as warm water dilute acid, dilute alkali, or organic acid may be used. Such fine particles can be selected from inorganic salts, organic salts, metal oxides, etc., but sodium chloride is the most suitable, considering its easy availability, cost, and disposal issues. Since these fine powders form a microporous structure in the sheet material of the present invention by being eluted, it is desirable to use powders having an average particle diameter of 0.1 to 20 .mu.m. In other words, if the average particle size of the added fine particles is larger than 20μ, the resulting molded product will have a coarse porous structure with many pores that can be seen with the naked eye, and physical properties such as strength and tearing strength will deteriorate, which is not desirable. . On the other hand, if particles with an average particle size of 0.1μ or less are used, it is difficult to completely elute the particles with the solvent after heat treatment.
More fine particles remain filled in the molded product,
Strong, breathability decreases. Therefore, in the present invention, the amount of solid fine particles to be dispersed and suspended in the emulsion is selected from a range of about 10 to 300% by weight based on the solid content of the elastomer polymer, depending on the desired physical properties of the target product. is suitable. In this case, the amount of the fine particles dissolved in the emulsion medium is not included. In the present invention, a small amount of a water-soluble polymer compound, for example, is added to prevent the fine particulate solid that forms the core of the microporous structure from coagulating on the surface during the dry coagulation process and to adjust the viscosity. It is also possible to add it to the emulsion in an amount of 10% by weight or less based on the solid content of the molecular elastomer. Examples of such water-soluble polymer compounds include sodium alginate, propylene glycol alginate, gum arabic, H.I. E. Examples include C. Further, in order to promote the formation of a film in the emulsion suspension liquid of these elastomer polymers, a solvent that dissolves the elastomer polymers may be added in an amount of about 1 to 10% based on the solid content of the elastomer polymers.

The suspension liquid of the emulsion thus produced is impregnated and/or applied to a fiber mat such as a raised woven fabric, a raised knitted fabric, a web, or a nonwoven fabric made by needle-punching these, or applied to a releasable substrate. Then, the polymer elastic body is fixed to the base by heat treatment at 40 to 200° C. for 1 to 120 minutes, for example.

This is mixed with a solvent that dissolves the solid particles, such as water, hot water,
When immersed in a dilute acid or dilute alkali bath, solid particles and surfactants are conveniently dissolved and removed, and the portions occupied by these become voids, forming a microporous structure obtained by the wet method. A microporous molded product having a structure relatively similar to the structure can be easily obtained. After dry heat treatment, this sheet-like material is dyed, surface coated, and
Surface decoration finishing treatments such as embossing and graining can be performed, and by such finishing, it is possible to produce artificial leather which has a multi-faceted appearance extremely similar to natural leather, and which is flexible and has good moisture permeability. The features and effects of the present invention will be explained below using specific examples.

Note that parts and percentages in the examples are based on weight. Example 1 Diphenylmethane diisocyanate 509 was added to polypropylene glycol 2009 having a molecular weight of 2000, and after reaction at 70°C for 2 hours, toluene 809 was added to obtain a prepolymer solution having isocyanate groups at the terminals.

To 100 parts of this prepolymer solution, 5 parts of polyoxyethylene nonylphenol ether (25 moles of ethylene oxide added) and 1 part of sodium dodecylbenzenesulfonate.
After adding and mixing 100 parts of an aqueous solution containing 3.29 parts of hydrazine, the mixture was dispersed using a colloid mill, and an aqueous solution 109 containing 3.29 parts of hydrazine was added to form substantially linear thermoplastic polyurethane resin particles with a diameter of 0.5 to 1 μm. A polyurethane dispersion was obtained. The solid content concentration of this dispersion was about 42%. Take 100 parts of this polyurethane dispersion in a vacuum mixer, add 10 parts of polyoxyethylene nonylphenol ether (trade name: Emulgen 950, HLB value 18.2, manufactured by Kao Atlas Co., Ltd.) and stir thoroughly until completely dissolved. Summer. This was crushed using a pole mill with an average particle size of 4
50 parts of common salt was added and thoroughly mixed and stirred to obtain an emulsion salt suspension.

The viscosity of this liquid was about 2000 centipoise. Place the above emulsion suspension on a glass plate. It was applied and heat treated at 140° C. for 10 minutes. This was taken out and immersed in boiling water at 98° C. for 30 minutes to elute the salt, and then peeled off from the glass plate and dried to obtain a microporous film. The measured physical properties of this film are summarized in Table 1.

For comparison, urethane TD. M. The values of the film obtained by wet coagulation from F solution (Crisbon 8166, manufactured by Dainippon Ink Co., Ltd.) are also listed. Example 2 Fineness 1.0 denier, cut length 421!1iIL25%
A web made from short polyethylene terephthalate fibers having a heat shrinkage rate of 0.25 mm was needle-punched and treated with boiling water to heat-shrink the fibers, resulting in a fabric weight of 8009/M2 apparent density of 0.05 mm.
34 nonwoven fabrics were created.

This nonwoven fabric was impregnated with the emulsion suspension liquid prepared in Example 1, squeezed to a pick-up of 200%, heat-treated at 120°C for 20 minutes, and then heated at 98°C.
The sample was immersed in a boiling water bath for 30 minutes to remove the salt and surfactant, and then dried.

At the same time, for comparison, the above nonwoven fabric was impregnated with the urethane emulsion of Example 1 diluted to 25% with water to a pick-up concentration of 200%, and dried at 120°C for 20 minutes to create a dry treated nonwoven fabric. . On the other hand, 10% polyvinyl alcohol (Gohsenol G) was added to the above nonwoven fabric.
A pretreated nonwoven fabric was prepared by impregnating the fabric with an aqueous solution (L-05, manufactured by Nippon Gosei Co., Ltd.), squeezing the liquid to 100% pick-up, and then drying it. The pretreated nonwoven fabric and the untreated nonwoven fabric were each impregnated with a polyurethane DFM solution diluted to 12% (Crisbon 8166, manufactured by Dainippon Ink Co., Ltd.), squeezed to a pick-up rate of 250%, and then placed in a water bath at 20°C for 1 hour. Soaked and solidified. The pretreated nonwoven fabric was subsequently immersed in a 98° C. boiling water bath for 30 minutes to extract and remove the pretreated polyvinyl alcohol, and then dried. When the cross sections of these four nonwoven fabrics were observed using electron micrographs, it was found that the fabrics simply impregnated with emulsion and heat treated, and the fabrics that were subjected to visible coagulation, had a structure in which the fibers and the impregnated resin were in close contact with each other. It was found that voids were observed between the fibers and the resin in the sample and the sample that had been pretreated, indicating that they had a non-adhesive structure.

These four nonwoven fabrics have a thickness of 0.711i! Table 2 summarizes the results of slicing into 1-inch pieces and measuring strength and elongation, bending hardness, initial Young's modulus, etc. It can be seen from this that the fabric obtained by the method of the present invention is a very flexible base fabric.

Example 3 Adipic acid-hexanediol-neopentyl glycol-polyester 2509 was dehydrated under vacuum at 120°C,
1. React with 38.6f1 of 6-hexane diisocyanate for 2 hours.

150T of acetone at 80℃ for a viscous melt! After adding Ll and making a solution, add 3.75 g of tartaric acid to 80 cc of acetone.
and a solution of 2.529 triethylamine in 30 d of acetone are added. After stirring for 1 hour at 50° C. the solution becomes very viscous and is then diluted with acetone 750WL1.

An opaque solution of polyurethane in acetone 4009 is diluted with 100 cc of acetone and mixed with 200 cc of water with vigorous stirring.
Gradually drip. During the addition of water, the solution first becomes very viscous and inhomogeneous, and then forms a thin milky emulsion. A 36% self-emulsifying urethane emulsion is obtained by distilling off the acetone. To 100 parts of this urethane emulsion, 5 parts of polyoxyethylene nonylphenol ether (Emulgen 950, HLB value 18.2, Kao Atlas Co., Ltd.) and 3 parts of a 5% alginate propylene glycol ester aqueous solution (Datsukloid PF Kamogawa Kasei Co., Ltd.) were added.
After adding 0 parts of dimethylformamide and 4 parts of dimethylformamide and stirring well to completely dissolve and disperse, add 6 parts of the finely ground common salt used in Example 1.
Add 0 parts and mix and stir to prepare an emulsion suspension liquid.

The viscosity of this liquid was 15,000 centipoise. Spread the above emulsion suspension liquid onto silicone release paper.
．． It is coated to a thickness of 4111t, heat treated at 130°C for 5 minutes, and further immersed in a 60°C hot water bath for 30 minutes to remove water-soluble polymer compounds, salt and activators, and dried to form a microporous flexible product. A film was formed. Table 3 summarizes the measured physical properties of this film.

Example 4 Stretch-crimped 1.0-denier nylon short fibers (cut length: 507!11 l) and stretch-crimped 1.0-denier polyester fibers with a heat shrinkage rate of 35% (cut length: 52 liters) were mixed at a ratio of 1:1 to create a random wave, and a needle-punched nonwoven fabric was treated with boiling water to create a nonwoven fabric with a basis weight of 500 g/M2 and an apparent density of 0.24.

This nonwoven fabric was impregnated with the emulsion suspension prepared in Example 3 except for alginate propylene glycol ester (viscosity: 850 centipoise), squeezed to a pick-up of 300%, heat-treated at 100°C for 20 minutes, and then Soak in warm water at ℃ for 30 minutes,
Salt and surfactant were removed and dried.

The emulsion suspension liquid prepared in Example 3 was applied to a base fabric obtained by slicing this impregnated nonwoven fabric into 0.8-thick pieces.
It was coated to give a weight of 3w1t and heat treated at 130°C for 5 minutes. Next, it was immersed in warm water at 60° C. for 30 minutes to remove the water-soluble polymer compound, salt, and nonionic activator, and then subjected to a dry heat treatment. Next, by coloring and surface treatment, flexible artificial leather with good moisture permeability could be produced. Example 5 To a solution of 2.8 parts of sodium lauryl sulfate in 140 parts of deionized water, 59.5 parts of n-butyl acrylate, 9.1 parts of acrylonitrile, 0.56 parts of methacrylamide, and 0.5 parts of methacrylamide were added. 84 parts of N-methylolmethacrylamide was added and mixed and stirred for 30 minutes while purging with nitrogen.

To this is added 2 parts of an aqueous solution containing 0.2 part of ammonium persulfate, followed by 2 parts of an aqueous solution containing 0.08 part of Rongalit.

The reaction temperature rises to about 50°C in a short period of time, but the temperature is maintained at that temperature in a cold bath. When the temperature has dropped, add 1 part aqueous solution containing 0.1 part ammonium persulfate and 0.02 part t-butyl hydroperoxide. After 4 hours, vinylidene chloride 29
．． 4 parts of ethyl acrylate and 0.6 parts of ethyl acrylate mixed with 60 parts of water were added, and after 15 minutes, a solution of 2 parts of aqueous solution containing 0.2 parts of ammonium persulfate and 3 parts of ethyl acrylate containing 0.12 parts of Rongalit was added.
When adding 1.0 parts of aqueous solution and 0.02 parts of t-butyl hydroperoxide, the temperature rose rapidly to 35-37°C and
The reaction ends after some time.

To this emulsion, polyoxyethylene nonylphenol ether (Emulgen 985 HLB value 19.2) was added.
(manufactured by Kao Atlas) weighs about 10? Dissolve and then add 60% by weight of the common salt used in Example 1. Add and adjust the emulsion suspension liquid.

On the other hand, fineness 1.5 denier fiber length 527U hot water shrinkage rate 25
% polyacrylonitrile fiber was needle punched and then treated with boiling water to obtain a fabric weight of 7509/M2.
A non-woven fabric with an apparent density of 0.33 was prepared, impregnated with the emulsion suspension liquid, and picked up at 250 mL.
%, heat treated at 120°C for 20 minutes, and then immersed in warm water at 80°C for 1 hour to extract and remove the salt and surfactant, yielding a soft nonwoven fabric with a good feel.

This non-woven fabric was sliced to a thickness of 0.8111R, and after the surface was covered with a hub, the emulsion suspension liquid used earlier was applied to a thickness of about 0.3571gt, and a dry heat treatment was performed at 100℃ for 30 minutes. It was immersed in warm water for 1 hour and dried to obtain a flexible leather-like sheet. Artificial leather can be produced by applying surface decoration techniques to the surface of this sheet using known methods such as dyeing, spray finishing, and molding as required. Example 6 100 parts of NBR latex (Crossrene NA-10, manufactured by Takeda Pharmaceutical Co., Ltd.): 6 parts of melamine resin, 0.
8 parts of polyoxyethylene nonyl phenol ether (Emulgen 985HLB value 19.2, manufactured by Kao Atlas) were further added and mixed and stirred using a homomixer to completely dissolve the mixture.

Thereafter, 40 parts of the same common salt used in Example 1 was added and mixed and stirred to prepare an emulsion suspension liquid. The same nonwoven fabric used in Example 2 was impregnated with this, the liquid was squeezed to a pick-up concentration of 250%, heat treated at 80°C for 40 minutes, and then immersed in warm water at 80°C for 60 minutes to remove salt and surfactant. was extracted and dried.

This nonwoven fabric was sliced to a thickness of 0.971μ11, and after hot pressing, the urethane emulsion suspension liquid used in Example 3 was applied to a thickness of 0.271R, heat treated for 10 minutes with ClO, and heated in 60°C hot water for 20 minutes. After soaking for a minute and drying, a very flexible artificial leather sheet with good moisture permeability could be produced.

Example 7 To prepare a microporous film in the same manner as in Example 1, 50 each of pulverized fine particles of four types of salts, potassium chloride, calcium carbonate, potassium stearate, and calcium acetate, were used instead of pulverized common salt. A film was prepared by adding the same amount.

Claims (1)

[Claims] 1. Solid fine particles are added to a polymer elastomer emulsion containing a surfactant in excess of the minimum amount required to prevent salting out of the polymer elastomer, and the resulting emulsion suspension liquid is applied onto a releasable substrate. Alternatively, a method for producing a flexible sheet material, which comprises impregnating and/or coating a fiber mat, subjecting it to heat treatment, and then removing it by treating it with a solvent that can dissolve the solid particles.