JPS60173179A - Production of artificial leather - Google Patents

Abstract

PURPOSE:To obtain a flexible artificial leather having high air and moisture permeability, by subjecting a porous sheet base material consisting of a nonwoven fabric containing a polyurethane elastomer to water repellent treatment, needling the base material for passing needles therethrough, and impregnating the resultant base material with a polyurethane elastomer. CONSTITUTION:A nonwoven fabric is impregnated with a solution of a polyurethane elastomer, and wet coagulated to give a porous sheetlike base material, preferably having 0.25-0.45g/cm<3> density, which is then subjected to the water repellent treatment and needled with needles having maximum 0.1-1mm. diameter at 10-500 needles/cm<2> needle density to pass the needles therethrough. A solution of a polyurethane elastomer is then applied to the resultant base material and wet coagulated to afford the aimed artificial leather having improved air and moisture permeability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing artificial leather having a polymer (porous polyurethane) coating layer. More specifically, the present invention relates to a method for producing artificial leather that is flexible and has high air and moisture permeability with good workability.

Japanese Patent Publication No. 48-4181 discloses 1, which is characterized in that, before applying a polymer solution to a porous sheet-like substrate (base material), the substrate is subjected to water repellent treatment with a water resistance of 20 cm or more. A method of manufacturing a sheet material having a coalesced covering layer is disclosed.

However, in this manufacturing method, air permeability and moisture permeability are reduced due to the water repellent treatment, and the coagulation effect of the coagulation liquid during wet coagulation occurs only from the coated surface (one side) of the polymer solution, so the coagulation rate is low. It is very slow and the production efficiency is poor, and if the water resistance of the base material is 20 or more, the adhesive strength between the base material and the polymeric storage layer becomes small and the peel strength becomes weak. Furthermore, this manufacturing method cannot be expected to improve flexibility.

In addition, in Japanese Patent Publication No. 50-11968, one piece of non-woven material is impregnated with synthetic resin, and after drying, a needle density of 10 needles with a maximum diameter of 0.25 to L5 and no protrusions on the side is used. A method for producing a base material for synthetic leather is disclosed, which is characterized by performing needling treatment to a depth of at least /d and at least 50% of the base thickness. However, since the base material obtained by this manufacturing method is not water-repellent, when the polymer solution is applied and wet coagulated, the polymer solvent or the coagulating liquid containing the solvent penetrates into the entire base material layer. Therefore, it takes a long time to wash the solvent and the solvent removal property is poor), which is not preferable from the viewpoint of production.

The inventors of the present invention have worked diligently to resolve the difficulties of the prior art, and as a result, in the case described below, (1) the synergistic effect of the carbon water treatment and needling treatment described below enables coating on the base material. To more completely prevent the occurrence of blistering and foaming due to gas inside the base during wet coagulation of polyurethane.

(2) The resulting artificial leather should have sufficient water repellency, which is required when processing it into shoe insole, cover type A, furniture upholstery, wall sheeting, etc.

(3) The polyurethane applied to the base material solidifies while penetrating deep into the formed needling holes, producing a so-called anchoring effect, which results in a bond between the base material and the polyurethane coating layer (string surface layer). Adhesive strength and peel strength are significantly increased (in addition, the drawbacks of the technique disclosed in Japanese Patent Publication No. 48-4181 are improved).

(4) When the polyurethane bath agent (dimethylformamide) is washed off with water after the coagulation of the polyurethane applied to the base material is completed, the needling holes (through holes) formed in the base material serve as passages for water and solvent. Since water flows through the through holes and washes both the front and back sides, solvent cleaning can be carried out efficiently and workability is good.

Also, in this case, the material has been treated to be water repellent, so
Penetration and absorption of the flowing solvent is prevented, and the effect of washing and removing the solvent with water is synergistically improved.

(5) By needling the base material as described below, the material itself becomes flexible, and the polyurethane solidifies quickly at the adhesive interface between the material and polyurethane, forming a covering layer with a soft microporous structure. Therefore, it is flexible, has a good texture and feel, and is breathable.
Artificial leather with high moisture permeability can be easily obtained.

and so on, and completed the present invention.

That is, the present invention provides a porous sheet-like base material obtained by impregnating a nonwoven fabric with a polyurethane elastomer solution and wet-coagulating the same, and applying a water repellent treatment and a needle density of 10 to 500 needles/
- This is a method for producing artificial leather, characterized in that a needling treatment is performed to penetrate the base material, and then a solution of a polyurethane elastomer is applied to the base material and wet-coagulated.

The porous sheet-like base material used in the present invention is obtained by impregnating the nonwoven fabric with a polyurethane elastomer and wet-coagulating the nonwoven fabric. Soaked and wet coagulated,
Obtained by washing with water and drying.

The nonwoven fabric may be made of natural or metal fibers with a fineness of 0. A nonwoven fabric made of short fibers of O1 to 50 denier, usually about 0.5 to 5 denier, either singly or in a mixture, or a three-dimensional nonwoven fabric made by needle-punching at least one sheet of the web and heat-treating it as necessary. , apparent density 0.05-0.85? It is preferable that the synthetic fibers have a fineness of 0.5 to 5 deniers, such as polyamide fibers, polyester fibers, polyolefin fibers, etc., as card wraps or random webs, and can be made into a single layer or multiple layers. Repeat needle punching treatment and heat treatment to give an apparent density of 0.1 to 0.3V.
It is a three-dimensional nonwoven fabric with /-.

The nonwoven fabric is impregnated with a polyurethane elastomer solution by immersing the polyurethane elastomer in a solution (WJ degree is usually 5 to 25%) in which the polyurethane elastomer is dissolved in a polyurethane solvent (e.g., dimethylformamide, dimethylamide, dimethyl sulfoxide, etc.). (The amount of impregnating air is usually 2 to 7 times the weight of the nonwoven fabric.) After that, the polyurethane is coagulated by introducing (immersion) into a coagulation bath (an aqueous solution for polyurethane elastomer, etc.), and then washed with water to remove the polyurethane solvent. The above-mentioned porous sheet-like base material can be obtained by sufficiently washing and removing the porous sheet and drying.

Preferred examples of the polyurethane elastomer include polyurethane elastomers such as polyester urethane, polyester urethane urea, polyether urethane, and polyether urethane urea.

In addition, an appropriate amount (50% or more of F) of other molding polymers (e.g., polyvinyl chloride <= yarn, polyamide, etc.) may be dissolved in the polyurethane elastomer as long as it does not impair the feel, performance, etc. of the product. You can also do it.

Note that the embodiments related to the polyurethane elastomer, its solution, wet coagulation, etc. described above also apply to the polyurethane elastomer applied to the substrate described below.

The density of the porous sheet-like material used in the present invention is usually 0.025 f/ctI or more, preferably 0.25 to 0.
．． It is 4fM/di.

In the present invention, the above-mentioned porous sheet-like base material is subjected to water repellent treatment and needling treatment with a needle density of 10 to 500 needles to penetrate the base material. The order of processing can be either earlier or later.
Appropriate selection will be made.

The water repellent treatment method involves immersing the base material in a water repellent solution or emulsion, impregnating it, squeezing the liquid with a nip roller, etc., and then determining the type of water repellent and the desired degree of water repellency (temporary). Depending on whether water repellency or permanent water repellency is desired, the heat treatment may be carried out in a conventional manner.

Examples of water repellents include aluminum soap, aluminum salt-paraffin emulsilon, zirconium salt-paraffin emulsilon, etc. After treatment, heat curing treatment is performed to permanently impart water repellency. Acid chloride acid anhydride, chlorocarbonate ester alkyl carbonate, etc., which have a long chain alkyl group that forms an ester bond with the processed material, and stearoylmethylamide methylene pyridinium salts and ethylene urea long chains that can form an ether bond with the processed material. There are alkyl substituted products, and other silicones such as methylhydrodiene polysiloxane and OH-terminated dimethylpolysiloxane, fluorine-based products such as perfluoromonocarboxylic acid chromium complex salts, acrylic acid fluorinated alkyl esters, and fluorinated J]lj acid amides. Examples include compounds. Among the stiffeners, Fluorine fiber-collecting compounds are the most preferred.

It is desirable that the needling treatment of the base material be performed under the above conditions.

The cross-sectional shape of the needle used is circular, flat, oval,
It can be triangular, square, rectangular, hexagonal, etc., and the outer shape may have slight protrusions or notches. Therefore, it is impossible to use a regular needle for needle punching nonwoven fabrics, but the tip of It is sharp. Also, the thickness of the needle, especially the thickness of the part that penetrates the base material, is important.
If it is too thick, there will be human marks on the base material side, which will reduce the value of the part, so it is preferable to make it as thin as strength allows, and usually the maximum diameter of the cross section of the needle that penetrates the base material is 0.1 to 1.0. Use bait.

Further, the needling treatment in the present invention needs to be performed so as to penetrate through the base material. If it is not penetrated, the product cannot be made soft and have a good texture and feel, as well as high air permeability and moisture permeability. In addition, it takes time to wash and remove the solvent after applying the polymer solution to the base material and wet coagulating it, resulting in poor workability.

The needle density of the needling treatment in the present invention depends on the type and denier of the fibers used in the base U, the type of polymer in the binder, the quantitative ratio of the fibers and the polymer, or the thickness and density of the base material. Although it is necessary to decide as appropriate depending on the
It is d. When the needle density is less than 10 needles/-, flexibility, air permeability, moisture permeability, blistering and foaming prevention effects, etc. cannot be sufficiently imparted and exhibited. On the other hand, if it exceeds 500 strands and 10 N, it is not preferable because the base material becomes weakened and the surface becomes rough due to the marks of the needles.

Further, this needle density is preferably selected within the above range in relation to water repellent treatment. As mentioned above, if the water repellent treatment is made too strong (the water resistance of the base material is 20 m or more), the adhesive force between the base material and the polyurethane-coated Wmn1 surface layer will decrease, and the peel strength will become weak, which is not desirable. Within the range of the needle density so that the water resistance of the base material is less than 20 cIn, preferably 5 to 15 by ring treatment,
It is preferable to select the conditions of the needle density. Note that the needling treatment may be performed using a cloth roll or the like in addition to the needling machine.

The porous sheet-like base material that has been subjected to water repellent treatment and needling treatment is coated with a solution of polyurethane elastomer by a conventional method (for example, knife coating method, roller coating method, etc.) for 1 to 1 hour, and then, After wet coagulation by immersion in the coagulation bath as described above, it is thoroughly washed with water to sufficiently remove the remaining solvent (for example, dimethylformamide), and dried to obtain the artificial leather targeted by the present invention. The artificial leather of the present invention thus obtained has extremely strong adhesion and peeling strength between the base material and the grain layer due to the polyurethane coating layer (grain layer) on the surface layer, making it flexible and giving a sense of fulfillment. It is an excellent artificial leather that has a good texture and feel, and has excellent breathability and moisture permeability.It is also very useful in industry, as it is easy to process into products. be. The following examples are all related to weight.

In addition, the moisture permeability, water resistance, and apparent elastic modulus shown in the examples are
The methods for measuring texture, surface (electrical composite coating layer surface) condition, strength and elongation, adhesive strength, and solvent removal property (residual solvent concentration) are as follows.

(1) Moisture permeability According to the method of JIS K-6549. -(2) Water resistance According to the method of JIS L-1092.

(8) Apparent (elastic coefficient) ■Measurement method The apparent elastic modulus is used for the purpose of quantifying the softness and texture.The measurement method is as follows.In the texture planning system manufactured by Kato Iron Works A sample piece of known thickness and width (4 to 5 cm in length) was placed in a KES-FB2 type pure bending tester.
) is attached, and the bending moment curvature curve is measured according to a conventional method over the range of curvature 0 to 2. From the obtained curve, the elastic modulus was calculated based on the following theoretical formula in which the bending rigidity value was subtracted from the initial straight line portion at a curvature of 0 to 1, and this was used as the apparent elastic modulus.

However, b: Width of the samurai piece h: Thickness of ■Ayaashi value and touch! f& (reference example) Appearance is elastic modulus, tactility 140 or more Hard Straight 100 or more 140 Hard 70 or above 100 breasts Normal 40 or more, less than 70, soft Less than 40 Very soft (4) Texture The texture was judged based on the results of touch tests by five specialized inspectors.

(5) Surface condition Judgment was made based on the results of inner eye observation by five specialized examiners.

(6) Strong elongation According to the method of JIS-6505.

(7) Adhesive strength Adhesive strength was expressed as the peel strength between the base layer with a width of 2.5 es and the polyurethane coating layer (grain layer).

(8) Measuring method for solvent removal (residual solvent concentration) A 25% solution of the coating polymer (polyurethane elastomer) in dimethylformamide was applied to a sample not coated with the polymer to a thickness of 1.0 mm.
After casting into a thin film with an area of 100ed (10s+X 10cII&), 80°C water (coagulation liquid)
t for 80 minutes to solidify the polymer bath solution, and then immersed in 8 tons of 60°C water (washing water) for 90 minutes to remove the solvent contained in the coagulated polymer. Elute dimethylformamide (natural washing). After soaking, take out the polymer coating, wipe off the water adhering to its surface with P paper, then fold the polymer coating from the center and press it strongly with pliers to remove the polymer and Place 1 to 2 drops of the liquid remaining inside the substrate (if dimethylformamide remains, it is an aqueous solution; if no dimethylformamide remains, it is a liquid consisting only of water) onto the sample plate of the Atsube refractometer. Squeeze it on top. Next, the refractive index of the liquid is measured. (This operation and measurement are performed in a constant temperature room at 25°C.) On the other hand, a calibration curve graph showing the relationship between the concentration of dimethylformamide and the refractive index in a dimethylformamide aqueous solution is created in advance, and this graph and the previously measured aperture are used. From the refractive index of the liquid, calculate the concentration (t% by weight) of dimethylformamide contained in the aperture number.

The lower the concentration, the better the solvent removal property after wet coagulation of the polymer solution (the solvent in the wet coagulation product is removed by water washing). This means that it was completely eluted and removed by washing with water.

Example 1 70 parts of nylon 6 short fibers with a fineness of 1.5 denier and a fiber length of 88 cm, and a highly shrinkable polyethylene with a shrinkage rate of 50% in water saving with a feed of a fineness of 1.5 denier and a fiber length of 85 cm. 80 parts of terephthalate short fibers were mixed, a random web was formed, and needle punching was performed to obtain a three-dimensional nonwoven fabric. The non-woven fabric was shrink-treated in 80°C hot water and dried in a cylinder dryer to a thickness of 1.4 m and an apparent chipping density of 0.20 f/.
- a shrinkable three-dimensional nonwoven fabric of polyethylene butylene (5:5 mol) adipate glycol with molecules j11500,
A polyurethane elastomer obtained by reacting p,p'-diphenylmethane diisocyanate and ethylene glycol (molar ratio 1:5:4) was immersed in a 15% dimethylformamide solution (liquid temperature 80°C), and this solution was applied to a nonwoven fabric. was impregnated with 400% water, and wet coagulated by immersion treatment in a 20% dimethylformamide aqueous solution adjusted to 40° C. for 20 minutes. Next, the solvent was removed by washing with warm water at 60°C for 1 hour, and the product was dried with hot air at 80°C. The apparent density of the porous sheet-like base material of the present invention thus obtained is 0.8.
It was 1 f/cd.

Next, the base material was coated with fluorine-based water repellent DickGuard A-2.
2 (manufactured by Dainippon Ink & Chemicals)) After immersing in a solution of Emulsilon and squeezing out the solution, the sample was dried with hot air at 120'C to adhere 0.5% of the water repellent component to the base material. The water resistance of this base material was 80c14.

The needle density for the water-repellent treated base material was set to 0 (no Dring treatment) and 5 needles/cd.

10 pieces/aJ, 50 pieces/cd, 100 pieces/eId125
Needling treatment was carried out by penetrating the base material from one side by vertical interlocking with 0 pieces/ai and 5oα pieces/−1800 pieces/−. The needle used had no protrusions or notches on its side, and the maximum cross-sectional dimension for penetrating the base material with a sharp tip was 0.5 s.
m triangle, 10a on the needling machine board
Plants planted at + spacing of 5 plants/- were used.

The base material (8 citrons) obtained as above was mixed with 25% of the polyurethane elastomer used as the binder, 1 lb of carbon black, and 74% of dimethylformamide.
After applying @ solution consisting of % to a thickness of 1.0g++,
It was immersed in an aqueous solution (coagulation bath) at 80° C. containing 20% dimethylformamide for 80 minutes to sufficiently solidify it.

Next, the solidified product was washed with hot water at 60°C for 90 minutes to remove the solvent, and then dried with hot air at 80°C. Table 1 shows the properties of the 8-shelf artificial leather obtained.

Table 1 ω It is water resistant.

In addition, all 8 types of artificial leather have a surface (M combined coating layer surface)
The condition was smooth and no blistering or foaming occurred.

As is clear from Table 1, when needling is not performed and when the needling needle density is 5 needles/d, the contact strength and moisture permeability are low, the solvent removal property is poor, and the texture is slightly hard. It became. In addition, the needling needle density is 800 needles/
In the case of ml, the strength and elongation tends to be low, so it can be seen that the desirable range is 10 to 500 pieces/ai.

Comparative Example 1゜The needling treatment in Example 1 was performed at a needle density of 50/-
The same procedure was repeated except that the needling needle was carried out until the tip of the needle reached 80% of the surface of the base material (without penetrating the base material).

The obtained artificial leather has a moisture permeability of 1.5 N/cd/
hr, and the apparent elastic modulus is 80kq/et1. in,
It was a little harder than when needling was performed through the base material, and the texture was poor in the sense of unity between the base material and the polymer coating layer. Furthermore, in terms of solvent removal, the residual solvent concentration is 8%.
and was inferior. The water resistance of the base material was 27 cIn, the strength of the artificial leather was 1.18#/-1, the elongation was 10B%, and the adhesive strength was 4.8cm/2.5cm.

Comparative Example 2 A needling treatment was performed to penetrate the base material at a needle density of 50 needles/d to form a polyurethane elastomer coating layer, and then a water repellent treatment was performed. (Produced in the same manner as in Example 1 except that water repellent treatment was carried out at the end.) The surface of the obtained artificial leather (the ff1M surface coated with polyurethane elastomer)
There were many traces of blistering and foaming, and the smoothness and appearance were very poor.

In addition, the strength of artificial leather is 1.18 / -5
The elongation is 100%, the permeability is 6.8#/2.5, the moisture permeability is 1.9*7aa7hr, and the apparent elastic modulus is 78#/2.5.
-1 residual solvent concentration was 8%.

Example 2 Highly shrinkable polyethylene terephthalate short mineral fibers with a fineness of 1.5 denier and a pole length of 855 m and a shrinkage rate of 50% in seawater were used to form a web using a card and a cross wrapper, and needle punching was performed. A three-dimensional nonwoven fabric was obtained. The nonwoven fabric was shrunk in 80°C hot water and dried in a cylinder dryer to a thickness of 1.4 m and an apparent density of 0.22 f.
/d (D Shrinkage three-dimensional nonwoven fabric is immersed in a 4% polyvinyl alcohol aqueous solution, and the liquid content is 120% of the nonwoven fabric M amount.
After squeezing the liquid until it became sandy, it was dried with hot air at 80° C. for 1 hour.

Next, this polyvinyl alcohol-impregnated fabric was dipped in 17% dimethylformamide of the same polyurethane elastomer as in Example 1 (temperature: 80°C) to impregnate the nonwoven fabric with 400% of this solution, and then soaked in a coagulation bath at 40°C. (dimethylformamide: water = 80 nia 0) for wet coagulation.

Next, the solvent was removed by immersion in warm water at 60°C for 1 hour, and then the pμ solution was immersed in warm water at 80°C 10 times to completely extract and remove polyvinyl alcohol over a period of L hours. When dried, the apparent density is 0. :116f/c
A porous sheet-like base material of Ii was obtained.

The water resistance of the base material was 5 degrees.

This base material was subjected to needling treatment by penetrating the base material using the same needling needle as in Example 1 at a needle density of 50 needles/aI, and then water repellent treated with aluminum salt-paraffin emulgedone to form a base material. When 0.5% of the water repellent component was applied to the surface, the water resistance was 14. Next, the same polyurethane elastomer solution as in Example 1 was applied to the same thickness, followed by wet coagulation, washing with water to remove the solvent, and drying, followed by molding on the surface by embossing. The obtained artificial leather is
Strength 1.28 paddy/-1 elongation 103%, adhesive strength 6.8k
Strong enough with Q/2.56n and moisture permeability of 8.1q/ad/
hr, and the apparent elastic modulus is 81/-, making it extremely flexible and having good surface smoothness, making it suitable for use as shoe uppers, bags, etc. It was a suitable material.

In addition, the residual solvent concentration was 0% in terms of solvent removal properties, and the workability was also good.

Comparative Example 8 The same treatment as in Example 1 was carried out except that no water repellent treatment was performed and only the needling treatment was performed to penetrate the base material at a needle density of 50 needles/d.

As a result, the surface of the obtained artificial leather (N combined coating layer surface)
Blistering and foaming marks were observed, and the smoothness was poor. In addition, the strength is 1.17 kf/d, the elongation is 101%, a
k iji force is 7.01c (j/2.5cm, moisture permeability is 2.111v/xi/hr, apparent elastic modulus is 7
The water resistance 1α of the base material was 2 kQ/ed and 4 crn.

Procedural amendment IF (spontaneous) April 1980 - LO date 1982 Patent Application No. 29344 2 Name of the invention Method for manufacturing artificial leather 3 Relationship with the case of the person making the amendment Patent applicant address Sumida-ku, Tokyo 5-17-4 Sumida 1-5-90 Tomobuchi-cho, Bejima-ku, Osaka 534 Tsukibo Co., Ltd. Patent Department Column "Detailed description of the invention" in the specification \a, /'6 Contents of amendment (1) "Single material" described on page 4, line 5 and page 4, line 10 of the specification is corrected to "base material."

(2) In the specification, page 8, line 8 to line 9 of the same page, "acid chloride acid anhydride" in fed cultivation is amended to "acid chloride, acid anhydride".

(3) "Chlorocarbonate ester alkyl carbonate" described on page 8, line 9 to page 8, line 10 of the specification is amended to "chlorocarbonate, alkyl carbonate".

(4) The “substrate layer” described in the second line of page 14 of the specification is “
Base material layer”.

Claims (1)

[Claims] (L) A porous sheet-like base material obtained by impregnating a nonwoven fabric with a solution of polyurethane elastomer and wet-coagulating the same is treated with water repellent treatment and has a needle density of 10 to 500 needles/d and penetrates through the base material. A method for producing artificial leather, which is characterized by subjecting the base material to a needling treatment, followed by applying a bath of polyurethane elastomer to the base material and wet-coagulating it.