JPS5943586B2 - Method for manufacturing leather-like sheet with good appearance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a lightly grained leather-like sheet with good appearance.

More specifically, by applying a polymer to the surface of the substrate having a porous coating layer, heat-setting it, and stamping it in a specific process, we create a high-quality shallow coating with excellent flatness, creases, color, texture, etc. The present invention relates to a method for producing a grained leather-like sheet.

Methods for imparting an uneven pattern to the surface of a leather-like sheet include a method of using a support such as a release paper or a polyethylene sheet having an uneven pattern when preparing the surface layer, and a method of applying an uneven pattern to the surface after preparing the base. Two methods are currently available: embossing with embossing rolls or embossing plates.

Among these, the former method is often used for synthetic leather, and although the reproducibility of the uneven pattern obtained from the support (release paper) is extremely good, the reproducibility of the uneven pattern of the support itself is incomplete, so the leather The appearance of the sheet, including its uneven pattern and gloss, is very artificial, giving it a strong image as a low-quality product.

On the other hand, the latter is made of artificial leather, and by appropriately adjusting the embossing conditions, not only the depth of the uneven pattern but also the artificial appearance seen with the above method can be reduced. It is possible to obtain an uneven pattern and luster similar to that of natural leather.

However, this latter method also has a major drawback when trying to obtain a clear, shallowly grained product.

That is, when conventionally attempting to obtain a shallowly textured product by embossing using the latter method, if the embossing conditions are weak, surface irregularities originally present on the substrate surface (for example, fiber irregularities on a fibrous base material or There is a drawback that impregnated spots of the binder, sponge spots of the porous coating layer, etc.) appear on the surface.

On the other hand, in order to solve this drawback, it is necessary to strengthen the embossing conditions by adjusting the embossing temperature, pressure, time, etc., or to apply a thick polymer layer containing a large amount of pigment (particularly titanium oxide). After that, by applying a finishing layer and stamping, it is possible to obtain a shallowly textured product with a certain level of sharpness, but it is still insufficient, and there is a new drawback that the folding texture required for high-grade leather-like sheets becomes extremely poor. occurs in

Therefore, shallowly grained artificial leather (particularly a leather-like sheet having a mirror surface or an uneven pattern of 50 μm or less) has a large difference in appearance from natural leather, and is currently treated as a cheap product.

SUMMARY OF THE INVENTION An object of the present invention is to provide a leather-like sheet that has good flatness, folding texture, and color appearance, and is provided with clear texture even in lightly textured products.

Another object of the present invention is that the uneven pattern is not artificial.
To provide a leather-like sheet with an extremely good appearance and a luxurious feel.

The present invention was achieved by applying a thin layer of polymer to a substrate, subjecting it to a surface smoothing heat-setting treatment using a special method, then applying a thin layer of polymer again, and then dyeing.

That is, in the present invention, a thin layer of polymer (polymer A layer) is applied to a substrate having a porous layer on the surface, and then the temperature of the pressure-bonded part is raised to 1.
20 to 180℃, the temperature of the peeled part is in the range of 30 to 120℃, and the temperature gradually decreases from the crimped part to the peeled part, and the temperature difference between the two parts is 20℃ or more. Appearance characterized by applying a thin layer of a pigment-containing polymer (polymer B layer) and a thin layer of an easily dyeable polymer (polymer C layer) in sequence after heat treatment, followed by dyeing. This is a method for producing a good lightly grained leather-like sheet.

First, the substrate in the present invention consists of a fibrous base material and a porous coating layer of a polymer.

The fibrous base material is a sheet-like material mainly composed of fibers such as nonwoven fabric, woven fabric, or knitted fabric, which is optionally impregnated and coagulated with a polymer as a binder.

Ordinary fibers can be used as the fibers,
Not only single spun fibers such as cotton, linen, wool, rayon, acetate, nylon, polyester, polyacrylonitrile, vinylon, and polyolefin, but also mixtures thereof, composite spun fibers, and the like can be used.

As the binder optionally added to the above-mentioned fibrous base material, any binder that is generally used for synthetic leather etc. can be used, such as natural rubber, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, etc. Polymers, polyvinyl chloride, polyurethane distomers, other synthetic rubbers, or mixtures thereof are used.

These binders are applied in an appropriate form such as a solution or an emulsion by an impregnation method, a coating method, or the like.

The amount of adhesion is usually within a range of 150% or less relative to the fiber.

A porous coating layer of a polymer is formed on one side of the fibrous base material.

As the polymer, polyurethane distomer, acrylonitrile-butadiene copolymer, polyvinyl chloride, polyamide, etc. can be used, and among them, polyurethane distomer having a nitrogen content of 3 to 7% by weight based on diisocyanate is preferable.

The polymer may contain fillers, softeners, stabilizers, antistatic agents, pigments, dyes, blowing agents, coagulation regulators, etc. as necessary.
It is possible to mix polymers with good compatibility in a solution state, such as polyvinyl chloride, polyvinyl acetate, polyvinyl formal, methacrylic acid resin, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, etc. can.

A preferred method for applying the polymer solution to the fibrous base material is a coating method, but it is also possible to separately prepare a porous coating layer on a support and then bond it to the fibrous base material.

A layer of polymer A is applied to the surface of the substrate in order to facilitate and make the subsequent heat setting uniform.

If the polymer A layer is not applied, even if the heat treatment and fixing conditions are strengthened, not only will it not be possible to obtain a uniform flat surface, but the folds and texture will also be poor.

For the polymer A layer, polymers commonly used for the surface finishing of synthetic leather, such as polyurethane distomer, polyvinyl chloride, nylon, nitrocellulose, etc., are used, but due to the stability of heat setting, It is best to use polymers based on diisocyanates (based on polyurethane di-stomers with a nitrogen content of 3 to 7% by weight).

Examples of polymers that can be used in combination with polyurethane distomers include polyvinyl chloride, methacrylic acid resin, nitrocellulose, polyvinyl acetate, polyvinyl formal, copolymers of vinylidene chloride and acrylonitrile, and copolymers of vinyl chloride and vinyl acetate. Stabilizers, foaming agents, etc. can also be used in combination, but the amounts used should be kept to an extent that does not inhibit the subsequent heat setting.

The thickness of the polymer A layer is approximately 10% from the viewpoint of creases, texture, flexibility, etc.
μ or less, particularly preferably 5 μ or less and 0.1 μ or more.

In the present invention, the substrate provided with the polymer A layer is subjected to surface smoothing heat setting treatment.

The purpose of the surface smoothing heat setting treatment in the present invention is to fix various irregularities (especially smoothness) on the surface of the substrate in a state where it is heated and smoothed without substantially destroying the porous structure of the substrate. It is to be.

Specifically, the surface to which the polymer A layer has been applied and which has been substantially dried is heated to a temperature of 120 to 180°C at the pressure bonding part.
, Continuous heat treatment on a smooth surface where the temperature of the peeled part is in the range of 30 to 120 °C, and the temperature gradually decreases from the crimped part to the peeled part, and the temperature difference in the image area is 20 °C or more.
This is a cooling operation.

The material used as the smooth surface is generally a metal plate or a metal roll, and these surfaces may also be coated with a special resin.

In the present invention, the purpose is to smooth and heat-set only the surface layer of the surface layer, and it is not preferable to perform the heat treatment and cooling operations rapidly, so it is generally recommended that a long time of 30 seconds or more is required. It is true.

To process the substrate operationally, place the surface of the substrate against the smooth surface of the crimped area, pressurize it with a back roll, etc., and then gradually lower the temperature while crimping it without applying pressure. This is done by peeling it off after it has been removed.

When a normal embossing roll is used, even the sponge inside the coating layer of the base material is greatly deformed, making it impossible to obtain sufficient flatness and causing very poor creases. The surface layer of the sponge is only slightly deformed, and flatness is obtained with almost no loss of texture or creases.

If the temperature of the crimped portion is 120° C. or lower, the contact with the metal plate or metal roll will not be perfect, and a flat surface will not be obtained.

On the other hand, if the temperature exceeds 180° C., even the sponge inside the coating layer will be deformed, which will not only result in poor folding but also make it difficult to stamp the material later.

If the temperature of the peeled part is below 30°C, the sticking will be too large and peeling will be difficult; if it is above 120°C, the heat fixation of the substrate surface will be insufficient and a flat surface will not be obtained.

Further, in order to sufficiently heat-fix the substrate surface and obtain a flat surface, it is also necessary that there be a temperature difference of 20° C. or more between the pressure-bonded portion and the peeled portion.

It is preferable that the metal plate or metal roll has a mirror surface or a pattern of protrusions and recesses with a depth of 70 μm or less in order to facilitate the subsequent coloring and to enhance the effects of the present invention.

Regarding the metal plate and metal roll, it is best to use an endless metal plate from the viewpoint of equipment cost, operating cost, ease of operation, etc.

The temperature of the crimping part can be controlled using steam, electricity, etc., and the temperature of the peeling part can be controlled using water, air, etc.

When using this apparatus to heat-treat a base fabric that does not adhere well to a metal surface, such as one that is very thick or heavy, or one that has been treated with a softener, it is advisable to preheat the base material and the metal surface before crimping.

Next, a polymer layer B layer is applied to cover up defects such as sponge spots and embedding that occur on the surface of the substrate.

The polymer B layer is composed of a pigment and a polymer, and the polymer can be approximately the same as the polymer A layer, but in particular, a polymer mainly composed of a polyurethane distomer with a nitrogen content of 3 to 7% by weight based on diisocyanate can be used. Combination is best.

In addition, as the pigment, either inorganic pigments or organic pigments can be used, but the former is preferred because it has a high hiding power, and the amount used is 1% to the polymer from the viewpoint of hiding effect, adhesion to the substrate, flexibility, etc. ~300% by weight is preferred.

The thickness of the polymer B layer is determined to be 10% from the viewpoint of creases, texture, flexibility, etc.
It is preferably 5 μ or less and 0.1 μ or more.

The substrate provided with the polymer B layer is further provided with an easily dyeable polymer C layer.

The purpose of applying the polymer C layer is to enable the desired color to be obtained by subsequent dyeing, as well as to improve gloss, touch, surface strength, etc. Furthermore, when stamping is performed next, It also has the purpose of facilitating this stamping.

For the polymer C layer, an easily dyed polymer such as an easily dyed polyurethane distomer, nylon, or a polyamino acid resin is used.

Among these, a polyurethane distomer containing polyethylene glycol in the soft segment and having a nitrogen content of 3 to 7% by weight based on diisocyanate is the best in terms of flexibility and shapeability.

The thickness of the polymer C layer is preferably 10 μm or less, particularly 5 μm or less and 0.1 μm or more, like the polymer A layer and B layer, and may contain polymers other than the above, colorants, stabilizers, Foaming agent 1. When using additives such as gloss modifiers, it is important not only to ensure that they do not impair the dyeability, appearance, physical properties, etc. of the product, but also to the extent that they do not interfere with the stamping that may be performed next. is necessary.

Next, if it is necessary to make the surface gloss of the leather-like sheet obtained in this way more beautiful or to add an embossed pattern to the surface, the surface of the leather-like sheet to which the B layer and the 0 layer have been applied is added. It is further stamped to give it a mirror surface or uneven pattern.

For the embossing, it is advantageous to use the ordinary embossing roll method from the viewpoint of productivity, and the conditions for this are that since a flat surface has been obtained in advance, the embossing should be lighter than usual, and the desired embossing pattern can be applied. Should.

In other words, the embossing must not damage the creases or texture.

Finally, dyeing is performed.

As dyes, dyes commonly used for dyeing synthetic leather, artificial leather, natural leather, etc. can be used;
Metal complex dyes are particularly suitable in terms of migration resistance.

Dyeing is carried out by dissolving these dyes in water or an organic solvent and using a jigger, wince, device that passes the solution continuously at a constant speed, or by methods such as gravure or spraying.

After dyeing, it can be washed with water, dried, etc., and then the color and gloss can be adjusted, fir processing, etc. can be carried out as necessary.

The leather-like sheet obtained in the manner described above has a high-quality appearance with excellent flatness and creases, as well as color, gloss, etc., as compared to conventional sheets.

The present invention is particularly effective for obtaining a leather-like sheet, that is, a smooth product, having shallow grains with a depth of 50 μm or less.

The present invention will be specifically described below with reference to Examples.

Note that all percentages in the examples are based on weight.

Example 1 Polybutylene adipate glycol, 4-butanediol and diphenylmethane were added to a nonwoven fabric of mixed spun fibers (mixing ratio 50:50) made of nylon and polystyrene.
N content consisting of 4,4'-diisocyanate is 4.7
% of polyurethane disstomer, 1% of carbon blank, 3% of water and 81% of dimethylformamide, and then the same solution was impregnated with a solid content of 80'f.
! /rri'' and treated with an aqueous solution containing 35% dimethylformamide at 40° C. for 30 minutes, followed by extraction and removal of polystyrene, solvent removal and drying to produce a porous substrate CI).

10% of the same polyurethane distomer as above on the base,
A solution consisting of 28% dimethylformamide, 38% acetone, and 24% cyclohexanone was applied to a solid content of 1.5 μm and dried (polymer A layer), and then the temperature of the pressure-bonded part was 160°C and the temperature of the peeled part was was treated for 90 seconds with an endless metal belt with a mirror surface heated to 96°C (
heat fixation).

In this processing method, the substrate is crimped onto a metal belt at the crimping section using a rubber bank roll (gauge pressure 1.5 ky/ffl), and then moved to the peeling section without applying pressure, and peeled off. completed.

The surface of the substrate after the heat treatment had extremely good flatness.

Next, 8% of the same polyurethane distomer used for the base material.
, carbon black 4%, dimethylformamide 22%
, a solution consisting of 41% acetone and 25% cyclohexanone was applied to a solid content of 2μ and dried to form a polymer B layer), followed by an N-containing layer consisting of polyethylene glycol, ethylene glycol and hydiphenylmethane-4,4'-diisocyanate. 5.5% polyurethane distomer 7%, dimethylformamide 18%, acetone 4
After applying and drying a solution consisting of 2% and 33% cyclohexanone to a solid content of 2μ (polymer C layer),
The enlarged pattern was embossed using an embossing roll method under conditions weaker than usual (steam pressure 3 kg/ca, pressure v, x,
Q. 5 kg/4, speed 7 m/min), and then dyed with a Tyco dyeing machine, which is often used for dyeing natural leather, under the following conditions, and dyed Nilgaran Blank GB.
L (C1ba Geigy metal complex dye) 2%
owf bath ratio: 1:100 Dyeing temperature: 260° C., dyeing for 50 minutes, washing with water, and drying at low temperature to obtain a leather-like sheet [layer A].

As shown in Table 1, the leather-like sheet) [''A) had good flatness and fold wrinkles, had many small, natural wrinkles on the surface, had a soft feel, and had an excellent color sense, so it was very good. It had a luxurious feel.

On the other hand, for comparison, the same polymer A layer, polymer B layer, and polymer C layer as above were sequentially applied to the same substrate CI as above without heat treatment (fixing) as above, and then the same shape as above was applied. Pressing under normal conditions (steam pressure 6 kg/
crA, press 2 kg/c, speed 4 m/min), and then subjected to fir treatment to produce a leather-like sheet [Layer B].

Compared to the above-mentioned leather-like sheet [Layer A], this material had poor flatness, creases, poor color feel, and soft feel (low commercial value).

On the other hand, a leather-like sheet [C] was produced in exactly the same manner as the leather-like sheet [A-layer] except that the same polyurethane di-stomer used for the substrate CI,1 was used in place of the polyurethane di-stomer of the polymer C layer.

This product had good flatness and creases like the leather-like sheet (A), but the color appearance was similar to that of the leather-like sheet (A).
It was worse.

Leather-like sheet [A leather-like sheet was obtained in the same manner as in the production of layer A, except that the embossing of the growth pattern was not performed.

This leather-like sheet is a leather-like sheet [A] in terms of surface gloss.
The results were equally excellent, except for the layer, which was slightly inferior to the layer.

Example 2 On a polyethylene sheet, polycaprolactone glycol, ethylene glycol and hydiphenylmecne-4.
A solution consisting of 8% polyurethane elastomer with an N content of 3.8% made of 4'-diisocyanate, 2% polyvinyl chloride, 1% titanium oxide, and 89% dimethylacetamide was applied to a solid content of 60 f/m''. The porous film was then treated with an aqueous solution containing 20% dimethylacetamide at 40°C for 30 minutes, followed by desolvation, peeling from the polyethylene sheet, and drying. A substrate (n) was manufactured by bonding using a polyurethane elastomer.

A solution consisting of 6% polyurethane elastomer, 2% polyvinyl chloride, 20% dimethylacetamide, 42% acetone, and 30% cyclohexanone as used for the coating layer of the substrate (III') was added to the substrate so that the solid content was 15μ. After coating and drying (polymer A layer), the leather-like sheet of Example 1 was applied (under the same conditions and using the same equipment as for layer A), except that the temperatures at the bonded part and the peeled part were 145°C and 65°C, respectively. Heat fixation was performed using

Next, a solution consisting of 8% of the same polyurethane distomer used for the coating layer of the substrate [■], 4% of a polycyclic organic pink pigment (manufactured by Inu Nichiseika Kogyo KK), 18% of dimethylacetamide, 42% of acetone, and 28% of cyclohexanone was added. was applied to a solid content of 4μ (polymer B layer), and then 6% of the same polyurethane elastomer used for the polymer C layer of Example 10, 2% of the same polyurethane distomer used for the porous film, and dimethyl A solution consisting of 16% acetamide, 44% acetone and 32% cyclohexanone was applied and dried to a solid content of 1.5 μm (polymer C layer).

Furthermore, the embossed pattern is embossed using an embossing roll method.
Under conditions weaker than usual (steam pressure 2 kg/crA, press 0.7 kg/c, speed 5 fufu 1/c), [Irgalan Red 2
BL J (metal complex dye manufactured by C1ba Geigy) 6%, dimethylformamide 8%, methanol 42
Leather-like sheet (D) was produced by sequential gravure and spraying of a solution consisting of % and 44% acetone, drying, and fir treatment.

This product also had good flatness, wrinkles, and color, and had a very luxurious feel.

On the other hand, heat-setting polymer B layer and polymer C layer were applied to substrate CII), embossing, dyeing, and fir treatment in the same manner as described above, except that the polymer A layer was not applied to the substrate CII). E) was produced.

Since the leather-like sheet [E] was not provided with the polymer A layer, the heat setting treatment was insufficient, and the flatness was much inferior to that of the leather-like sheet [E].

Furthermore, for comparison, polymer A was added to the substrate (n) in the same manner as above.
After applying the layer, heat setting is performed, and the polymer C layer is applied in the same manner as above without applying the polymer B layer, embossing,
A leather-like sheet (F) was produced by dyeing and fir treatment.

The leather-like sheet CF) had good flatness and wrinkles, but compared to the leather-like sheet (D, :), the sponge spots and embeddings on the substrate surface that occurred during porous film production also appeared on the product surface. The product value was low because it was conspicuous and the desired color could not be obtained.

Claims (1)

[Claims] 1. A thin layer of polymer (polymer A layer) is applied to a substrate having a porous layer on the surface, and then the temperature of the pressed part is 120 to 18
0℃, the temperature of the peeled part is in the range of 30 to 120℃, and the temperature gradually decreases from the crimped part to the peeled part, and the temperature difference in the image area is 20℃ or more. Good appearance characterized by applying a thin layer of a pigment-containing polymer (polymer B layer) and a thin layer of an easily dyeable polymer (polymer C layer) in sequence after heat treatment, and then dyeing. A method for producing a lightly grained leather-like sheet. 2. The manufacturing method according to claim 1, wherein the substrate is stamped after applying the polymer C layer and before dyeing. 3. The manufacturing method according to claim 1 or 2, in which a diisocyanate-based (polyurethane distomer with a nitrogen content of 3 to 7% by weight) is used for the substrate, polymer A layer, B layer and O layer. 4. The manufacturing method according to any one of claims 1 to 3, wherein the substrate comprises a porous fibrous base material impregnated with a polyurethane elastomer and a porous coating layer of a polyurethane nidistomer. 5. Polymer C The manufacturing method according to any one of claims 1 to 4, which uses a polyurethane distomer containing polyethylene glycol as a soft segment in the layer.6 As a heat treatment device, a mirror surface or an uneven pattern with a depth of 70μ or less is used. The manufacturing method according to any one of claims 1 to 5, in which a flat endless metal plate (belt) is used. 1. The manufacturing method according to claim 2, in which the stamping is performed by an embossing roll method. .