JPS5810516B2 - Suede - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing suede-like synthetic leather.

A sheet with a base fabric coated with a single layer or two layers of a polymer solution containing polyurethane distomer as a main component is coated with a coagulating liquid that is miscible with the solvent of the polymer solution but is a non-solvent for the polymer. A porous polymer layer is formed on the base fabric surface by a so-called wet coagulation method in which the polymer layer is coagulated by treatment with
A number of methods are known for producing synthetic leather with a suede-like surface by subsequently dividing the porous polymer layer into two sheets.

However, in all of the above-mentioned known methods, after the polymer layer has completely solidified, the porous layer of the polymer is torn off in the middle and divided into two sheets. The thickness will be non-uniform and sometimes the polymer layer will peel off from the base fabric.

In addition, in order to obtain two pieces of synthetic leather by the above method,
Since the base fabric is attached to the surface of the solidified polymer layer using an adhesive, the adhesive penetrates into the porous layer of the polymer and its texture deteriorates, and the process for attaching the base fabric is difficult. I need.

On the other hand, a foamed sheet made of thermoplastic synthetic resin such as polypropylene with base fabric on both sides is heated, the film forming the sheet is stretched in a direction perpendicular to the plane, and the film is broken in the middle to form two sheets. Method of producing a raised sheet (
(see Japanese Patent Laid-Open No. 49-14578) is known.

In the above method, two sheets can be obtained at the same time and the process is simple, but since the resin is divided into two sheets in a softened state, the porous film stretches and is cut, causing fuzz. When the fluff is formed, the fluff is fused and the fluff is contracted by cooling, so that the fluff is small and a uniform surface cannot be obtained, and in addition, the surface becomes honeycombed and uneven gloss occurs.

This invention eliminates the drawbacks of the method for manufacturing suede-like synthetic leather having a bubble layer of polyurethane elastomer described above, and eliminates the unevenness of the film thickness of the two divided sheets (the fuzz is long and thin). To provide a method for obtaining suede-like synthetic leather through a simple process.

That is, the present invention provides a sandwiching sheet in which a polymer solution containing polyurethane elastomer as a main component is sandwiched between two base fabrics, which is miscible with the solvent of the polymer solution, but does not contain the polymer. The laminated sheet is treated with a coagulating liquid, which is a non-solvent, so that the amount of residual solvent in the laminated sheet becomes 5 to 50% by weight to form a semi-solidified polymer layer. A method for producing suede-like synthetic leather, which comprises dividing the two sheets in the polymer layer, and then treating the obtained two sheets again with a coagulating liquid to completely coagulate the polymer layer, and further drying. It is.

The polyurethane elastomer in this invention is generally referred to as polyurethane, polyurethane urea distomer, or polyurea elastomer, in which polyalkylene ether glycol or polyester having a hydroxyl group at the end is reacted with an organic diisocyanate, and this is reacted with an isocyanate-terminated prepolymer. Alternatively, it is an elastic body obtained by chain elongation with a compound having two active hydrogens without using a prepolymer.

The polyalkylene ether glycol useful for the above reaction has a molecular weight of 300 to 5000, preferably 40.
0 to 2000, such as polyethylene ether glycol, polyalkylene ether glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, polynonamethylene ether glycol, polydecamethylene ether glycol, polydodecamethylene ether glycol, and these A mixture of polyether glycols, as well as those with several different groups in the molecular chain.

Polyesters that can be used in place of or in combination with the above-mentioned polyalkylene ether glycols are those obtained by reacting mono- and polyglycols with carboxylic acid compounds or halides thereof.

The organic diisocyanate to be reacted with the polyalkylene ether glycol or polyester is an aromatic, aliphatic, or cycloaliphatic diisocyanate compound, such as 4-methyl-m-phenylene diisocyanate, 4-methyl-m-phenylene diisocyanate, or 4-methyl-m-phenylene diisocyanate.
4-biphenylene diisocyanate, methylene bis(4
-phenylisocyanate), 1.4-cyclohexylene diisocyanate, 2.6-hexamethylene diisocyanate, and the like.

Compounds having two active hydrogens used as chain extenders include hydrazine, ethylene diamine, propylene diamine, tetramethylene diamine, water, ethylene glycol, diethylene glycol, propylene glycol, and the like.

The above polyalkylene ether glycol or polyester and a diisocyanate compound are blended so that no isocyanate group remains at the end of the polyurethane distomer product, and the average molecular weight is 30,000 to 11,000.
Get something in the 0 range.

The polyurethane elastomer obtained as described above is applied as a polymer solution to the base fabric surface, and the solvent used is dimethylformamide, dimethylacetamide,
Preferred are tetrahydrofuran, tetramethylurea, dioxane, and the like.

The polymer solution may contain other polymers as necessary, such as polyamide, polyester, polyacrylonitrile, polyvinyl chloride, vinyl chloride/vinyl acetate copolymer, butadiene-acrylonitrile rubber, butadiene-styrene rubber. , chloroprene rubber, isoprene rubber, etc. can be mixed.

The mixing ratio of these other polymers is 3 to the total amount of polymers.
It is 0% by weight or less, and by mixing the above polymer, the flexibility and moisture permeability of the product are improved.

A pore-forming agent is added to the polymer solution in order to make the fluff thinner, if necessary.

Pore-forming agents include compounds that are insoluble in the solvent of the polymer solution but soluble in the non-solvent of the polymer, such as sodium bicarbonate, sodium carbonate, ammonium bicarbonate, sodium sulfate, polyvinyl alcohol, and starch. 30-500
It is used in powdered form.

The addition of this pore-forming agent reduces the number of thin strings that occur when dividing the semi-solidified polymer layer, making division easier and thicker, and improving the moisture permeability and flexibility of the product.

The amount of pore-forming agent added is 1 part by weight of the polymer component.
The amount is less than 1,000 parts by weight, preferably less than 500 parts by weight, and if it exceeds 1,000 parts by weight, the bristles become too thin (too thin) and easily break, and the scratch strength and abrasion resistance of the product decrease.

Other additives include surfactants such as sulfonic acid esters, polyhydric alcohol esters, fatty acid esters, and fatty acid metal salts, and these surfactants act as coagulation accelerators and foam regulators.

Further, as additives, coloring agents such as pigments and dyes, and fillers such as calcium carbonate, talc, and clay can also be added.

Furthermore, it is possible to add a masking isocyanate as a reinforcing agent, and when this is added, a crosslinking effect is produced by heating.

Note that by adding a small amount of coagulation liquid to the polymer solution in advance, the half-coagulation time can be shortened and a stronger fluff can be formed.

The polymer content contained in the above-mentioned polymer solution mainly composed of polyurethane elastomer is 6 to 25% by weight, preferably 10 to 15% by weight, and the total solid content including additives is It is 6 to 80% by weight.

The content of the polymer component and total solid content in the polymer solution is appropriately adjusted depending on the solution viscosity suitable for the means for applying the polymer solution to the base fabric surface.

The polymer solution is sandwiched between two base fabrics as an intermediate layer.

That is, a polymer solution is applied to each side of two base fabrics by conventional means such as a doctor knife, a roll coater, a reverse roll, a spray, and an extrusion sandwich coating, and the coated surfaces are overlapped.

Ru.

Alternatively, two base fabrics may be passed between a pair of clearance rolls, and the solution may be spread between the two base fabrics and sandwiched between the two base fabrics.

The amount of polymer solution applied is 100 to 500 f/m2, preferably 160 to 400 f/m2, preferably 160 to 400 f/m2 of the polymer component to the two base fabric surfaces.
? /m2.

As the base fabric, woven fabrics, knitted fabrics, nonwoven fabrics, and raised products thereof are used.

Note that these base fabrics may be impregnated or coated with resin, synthetic rubber, etc. in advance.

The sandwich sheet obtained as described above is miscible with the solvent of the polymer solution, but is treated with a coagulation liquid that is a non-solvent for the polymer, the so-called wet coagulation method. be done.

As such a coagulating liquid, water, alcohol, ethylene glycol, glycerin, acetone, methyl ethyl ketone, ethyl acetate, a mixture of these and water, etc. are used.

These coagulation solutions contain 30% by weight of the solvent in the polymer solution.
In this case, the polymer coagulates slowly and the degree of coagulation of the polymer can be easily adjusted.

When the sandwich sheet is immersed in the coagulation liquid, the coagulation liquid penetrates through the base fabric into the polymer solution layer, which is the middle layer of the sandwich sheet, and replaces the solvent in the polymer solution layer from the part near the coagulation liquid. The polymer solidifies and becomes porous.

That is, coagulation of the polymer starts at the interface with the base fabric and progresses sequentially from both sides of the polymer solution layer toward the center.

The sandwich sheet can be treated with a coagulating liquid by spraying the coagulating liquid onto both sides of the base fabric of the sandwich sort, but the substitution reaction proceeds at the same rate from both sides of the polymer solution layer. It is necessary.

In the case of spraying, it may be applied from both sides of the sandwiching sheet under equal conditions.

When the solvent in the polymer solution sandwiched between the sandwiching sheets and the coagulation liquid have been replaced to some extent and the polymer becomes a semi-solidified laminated sheet, this laminated sheet is divided into two sheets from the middle of the polymer layers. divided into

Here, the semi-solidified state of the polymer is a state in which the remaining solvent in the laminated sheet is replaced with a coagulating liquid until the amount of residual solvent becomes 5 to 50% by weight based on the amount of the original solvent.

The time it takes to reach this semi-solidified state varies depending on the solid content of the polymer solution, the amount of polymer attached, and the type and temperature of the coagulating liquid, but if the coagulating liquid temperature is 5 to 60°C, the processing time is 2 to 15 minutes.

Note that it is not preferable that the temperature of the coagulating liquid exceeds 60° C., since the pore-forming agent to be removed by the coagulating liquid treatment after division will be prematurely eluted and decomposed.

The semi-solidified polymer layer is divided by pulling the two base fabrics that make up the laminated sheet in opposite directions.
Fuzz is produced by the stringing phenomenon of the semi-solidified polymer.

And polyurethane elastomers containing urea bonds are
It is desirable that the polyether type urethane distomer can be divided while the above solvent substitution rate is relatively small, and the polyether type urethane distomer can be divided while the substitution rate is high.

The above division can be carried out either while the laminated sheet is immersed in the coagulation liquid or after it has been removed from the coagulation liquid, but if it is carried out while it is immersed, the fuzz produced by stringing on the dividing surface will immediately start coagulation. Therefore, it is preferable.

When dividing outside the coagulation solution, the next treatment with the coagulation solution may be performed before the fluff produced before the division shrinks.

The two sheets divided in the above manner are then treated with a coagulating liquid to remove the solvent in the semi-solidified polymer layer, completely solidify the polymer, and elute the pore-forming agent. Ru.

The coagulating liquid treatment at this time may be performed in the same bath as the treatment before division or in a separate bath (at this time, the coagulating liquid temperature is raised,
A temperature of 40 to 100°C promotes coagulation, and the treatment time is 5 to 60 minutes.

The sheet is dried when the coagulation is complete, that is, the solvent in the solution layer has been removed and the pore-forming agent has been eluted.

The drying temperature depends on the type of coagulating liquid, but is in the range of 70 to 120°C above its boiling point.

After drying, the polymer layer is subjected to surface treatment if necessary.

This surface treatment includes softening treatment using a polyhydric alcohol or higher fatty acid-based surfactant, and water-repellent treatment using methylhydrogen-based silicone, paraffin, or the like.

Embossing of the polymer layer is also possible, and the temperature at this time depends on the type of polyurethane elastomer, but a suitable temperature is 100 to 150°C.

As explained above, this invention divides a laminated sheet in a semi-solidified state in which the polymer layer between two base fabrics is not completely solidified, and that the coagulation starts from the base fabric side. Since this is done before the center of the polymer layer has been reached in the thickness direction, it is easy to divide the polymer layer from the middle to an even thickness, and the stringing phenomenon during division creates fine (long) fuzz. If the same material is used for the two base fabrics, two similar suede-like synthetic leathers can be obtained.

Further, since the polymer layer can be easily divided, a flexible thin base fabric may be used, or one of the two base fabrics may be made of thick material and the other may be made of thin material.

The suede-like synthetic leather obtained by this invention has good flexibility and breathability, has fine surface fluff, and has an excellent texture, and can be widely used for clothing, bags, shoes, upholstery, etc.

This invention will be explained in detail below.

In the Examples, "1 part" and "%" are expressed on a weight basis unless otherwise specified.

Example 1 A polymer solution having the following composition was prepared.

Polyester type urethane elastomer (average molecular weight 100,000) 100 parts Sodium bicarbonate 300 parts Pigment
15 parts Dimethylformamide 400 parts The above polymer solution containing 12.2% of polyurethane distomer was applied in an amount of 14007/m2 between the facing raised surfaces of two plain woven fabrics woven from rayon/vinylon blend yarn. The resulting sandwiched sheet was immersed in water at 18°C for 7 minutes to bring the polymer layer into a semi-solidified state (residual solvent amount: 32%), and then this laminated sheet was divided into two sheets. Then, dimethylformamide and sodium bicarbonate were eluted by immersion in warm water at 70° C. for 30 minutes.

This divided sheet was dried at 120° C. to obtain a single layer of polyurethane paint with long fluff.

Next, a polyhydric alcohol surfactant was applied at an amount of 5 v/m2, and a methylhydrodiene silicone was applied at a solid amount of 3? /m2.

The obtained sheet is a suede-like synthetic leather that closely resembles natural leather and is suitable for clothing, with a moisture permeability (JIS-ZO208) of 1500 at a relative humidity of 90%. /m2 ・24
Time, scratch strength is 700? /mm2, the bending strength at -5°C was 100,000 times or more.

The scratch strength was measured using a Clemens scratch tester.
A needle with a base area of 1 mm2 is moved at a speed of 1 m/min, and the bending strength is indicated by the minimum load (?/mm2) at which the surface breaks. Fold it in half, grab it at 30mm intervals, make a hole in the center, and use one gripping piece with a stroke of 20mm.
It is made to reciprocate at a speed of 220 times/min (giving repeated bending,
This value is expressed as the number of times cracks first appear on the coating surface.

In relation to Example 1 above, samples were prepared under the same conditions except that only the time of coagulation solution treatment before polymer layer division was changed, and the results of observing the surface state of the samples are shown in the table below.

Treatment time Amount of residual solvent Surface condition (minutes) (%) 1 87 Uneven gloss with few cells standing, 2 71 Parts with few cells standing 358 Same as above 449 Good 541 Good 7 32 Good (Example 1) Treatment time Residual solvent Quantity Surface condition (min) (%) 915 Good 10 7 Good 11 5 Short pile 13 4 Uneven thickness 15 3 Same as above. Note that here, "good" surface condition means 200 to 30
0x40-50μ elliptical (indentation) is a case where uneven (occurs), "few cell standing" means a state in which there is a mixture of 4-5μ (4-5μ) (40-300μ) spherical (indentation) means.

Example 2 A polymer solution (polyester type urethane elastomer content: 15%) having the following composition was prepared.

Polyester type urethane elastomer (urea bond 15%, average molecular weight 30 parts 5o
ooo) Dimethylformamide 170 parts Pigment
A nonwoven fabric having a basis weight of 2007/m 2 manufactured by a three-part needle punch method was impregnated with a polyurethane disstomer solution for impregnation to a solid content of 30 P/m 2 to obtain a base fabric.

The above polymer solution was applied to this base fabric at a solution application amount of 1100 f/m2, and another base fabric of the same quality as above was layered on the coated surface to form a sandwich sheet, and this sandwich sheet was heated at 18°C. Immerse it in water and after 4 minutes it will be in a semi-solidified state (remaining solvent amount 45%).
) was divided into two sheets, each divided sheet was immersed in warm water at 50°C for 15 minutes to completely elute dimethylformamide, and further dried at 120°C.

The porous polymer layer of the obtained sheet has fluff;
The resulting sheet was a suede-like synthetic leather with a long pile and similar to natural leather for use in shoes.

The moisture permeability of this synthetic leather is 1300? /m2・24 hours, strong scratch cuff 00? /mm2, and the bending strength was 100,000 times or more.

Further, the apparent specific gravity of the polymer layer was 0.5.

Example 3 A mixed solution of a polyurethane elastomer and a vinyl chloride/vinyl acetate copolymer having a polymer content of 10.4% was prepared with the following composition.

Holieste dead type urethane elastic s 5 parts tomer (average molecular weight 90000) Vinyl chloride/vinyl acetate copolymer (vinyl chloride/vinyl acetate 15 parts polymerization ratio 8)
5/15) Ammonium bicarbonate 400 parts pigment
15 parts dimethylformamide
A polyurethane elastomer solution for fluffing is applied to one side of each of a raised plain fabric and a raised tricot made of 450 parts of cotton yarn using a print roll so that the amount of polyurethane elastomer applied is IOP/m2, and fluffing is performed. The solvent was removed by heating and each fabric was used as a base fabric.

The above-mentioned polymer mixed solution was applied to each of the coated surfaces of both base fabrics at a coating weight of 5007/m2, and the coated surfaces were overlapped to obtain a sandwich sheet with a total coating weight of foo07/m2.

This sandwich sheet was immersed in water at 18°C, and after 4 minutes, the laminated sheet, which had become semi-solidified (residual solvent amount 47%), was
Divided into pieces.

Each divided sheet was immersed in warm water at 70°C for 15 minutes,
Dimethylformamide and ammonium bicarbonate were eluted and then dried at 120°C.

All of the obtained divided sheets had a porous polymer layer with fluff and long piles, and were suede-like synthetic leather similar to natural leather.

Those using tricot as the base fabric were ideal for clothing, and those using plain woven fabric as the base fabric were ideal for shoes.

In addition, these products have a moisture permeability of 1900? /m2・24
The scratch strength was 600 guamm, and the bending strength was 100,000 times or more.

Claims (1)

[Claims] A sandwiching sheet in which a polymer solution containing polyurethane diastomer as a main component is sandwiched between 12 base fabrics is used, which is miscible with the solvent of the polymer solution but is a non-solvent for the polymer. The amount of residual solvent in the laminated sheet is 5 to 50 with a coagulating liquid of
% by weight to form a semi-coagulated polymer layer, then this laminated sheet is divided in the semi-coagulated polymer layer, and then the two sheets obtained are again treated with a coagulating liquid. A method for producing suede-like synthetic leather, which comprises processing to completely solidify the polymer layer, and further drying.