JPS5943588B2 - Manufacturing method for high-quality leather-like sheets - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for producing a leather-like sheet with a luxurious feel.

More specifically, by applying a polymer to a substrate consisting of a fibrous base material and a porous coating layer, heat treatment, and special stamping in a specific process, flatness, color uniformity, creases, etc.
This invention relates to a method for producing a leather-like sheet with excellent color and texture.

Methods for imparting an uneven pattern to the surface of artificial leather or synthetic leather include a method of using a support such as a release paper or a polyethylene sheet having an uneven pattern when producing the surface layer;
There are two methods of embossing the substrate with an embossing plate or an embossing roll having an uneven pattern on the surface after the substrate is prepared.

Of these, the former method is often used for low-grade synthetic leather, and the reproducibility of the uneven pattern obtained from the support (release paper) is extremely good, but the reproducibility of the uneven pattern of the support itself is poor. Because of its perfection, the appearance of the leather-like sheet, including its uneven pattern and gloss, is very artificial, giving it a strong image as a low-grade product.

On the other hand, the latter method is often used for artificial leather, and by appropriately adjusting the embossing conditions, it is possible to improve not only the depth of the uneven pattern but also the artificial appearance recognized by the above method. Even less, a textured pattern similar to that of natural leather can be obtained.

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 the fibrous base material or binder) may occur. There is a drawback that impregnated spots, sponge spots, sponge spots on 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 humidity, pressure, time, etc. of embossing, or to make the polymer layer containing a large amount of pigment (particularly titanium oxide) thicker ( After application, by applying a finishing layer and pressing, it is possible to obtain a product with a somewhat excellent shallow grain, but it is still insufficient and has the disadvantage that the folding grain required for high-grade leather-like sheets becomes extremely poor. arise anew.

A special embossing method, that is, a method in which a certain clearance is provided between the embossing roll and the back roll and embossing is performed slowly, has been proposed.

However, this method also has poor productivity and does not provide sufficient flatness.

Another special stamping method has been proposed, in which stamping is performed while heating and cooling continuously. However, if this method is simply adopted, a fairly flat surface can be obtained, but the creases will be poor. There was a drawback that it was easy to become.

For this reason, 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 and creases, and is provided with clear grains even in lightly grained products.

Another object of the present invention is to prevent the uneven pattern from being artificial (
To provide a leather-like sheet with an extremely good appearance including a sense of color and a luxurious feel.

Still another object of the present invention is to provide the best method for producing an industrially high-grade leather-like sheet with easy color control, in addition to achieving the above-mentioned objects.

In the present invention, a thin layer of a polymer is applied to a substrate, heat treated with a flat embossing roll, a thin layer of a pigment-containing polymer and a thin layer of an easily dyed polymer are applied, and then a special method is applied to the substrate. This is accomplished by stamping the desired shape and then dyeing it.

That is, in the present invention, a polymer A layer is applied to a substrate consisting of a fibrous base material and a porous coating layer, and then heat treated with a flat embossing roll, and then a pigment-containing polymer B layer and an easily dyed polymer C layer are formed. are sequentially applied until the temperature of the crimped part is 120 to 180℃.
, a flat metal having a desired grain, in which 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 between the two parts is 20 °C or more A method of manufacturing a leather-like sheet that has flatness and color uniformity, and has excellent creases, color feel, texture, etc. by continuously stamping with a metal roll and then dyeing. It is.

According to the present invention, products with high commercial value that are comparable in appearance to natural leather can be obtained, especially in shallowly textured products with an uneven pattern of 50 μm or less.

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

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

Ordinary fibers can be used as the fibers,
Any single spun fibers such as cotton, linen, wool, rayon, acetate, nylon, polyester, polyacrylonitrile, vinylon, polyolefin, etc., as well as mixtures thereof, composite spun fibers, etc. 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 elastomers, other synthetic rubbers, or mixtures thereof are used.

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

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

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

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

The polymer may optionally contain fillers, softeners, stabilizers, antistatic agents, pigments, dyes, blowing agents, coagulation regulators, etc., as well as polymers with good compatibility in the solution state, such as polychloride. Vinyl, polyvinyl acetate, polyvinyl formal, methacrylic acid resin, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, etc. can be mixed.

A preferred method for applying the polymer solution to the fibrous 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 material.

A layer of polymer A is applied to the surface of the substrate to facilitate subsequent heat treatment and to obtain a uniform surface.

If the polymer A layer is not applied, the heat treatment will not be carried out satisfactorily, resulting in an uneven surface, which will greatly hinder the subsequent application of the polymer B layer and polymer C layer. This will result in inclusion.

For the polymer A layer, polymers commonly used for the surface finishing of synthetic and artificial leathers, such as polyurethane distomer, polyvinyl chloride, nylon, and nitrocellulose, can be used, but the stability of heat treatment It is best to use a polymer mainly composed of a polyurethane elastomer having a nitrogen content of 3 to 7% by weight based on diisocyanate from the viewpoint of flexibility and flexibility.

Polymers that can be used in combination with polyurethane elastomers 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. etc., and also colorants,
Foaming agents and the like can also be used, but the amount used should be limited to an amount that does not interfere with the subsequent heat treatment.

The thickness of the polymer A layer is 1 in terms of creases, texture, flexibility, etc.
It is preferably 0μ or less, particularly 5μ or less and 0.1μ or more.

Then, the surface of the substrate is heat treated.

The purpose of the heat treatment is to eliminate to some extent in advance unevenness on the surface of the substrate and density unevenness on the surface layer of the substrate due to the unevenness of the fibrous base material due to the unevenness of the density or the local swelling or depression of the sponge that often occurs during the solidification process. The purpose of this method is to uniformly apply a colored polymer solution which is then applied uniformly.

For heat treatment, it is advantageous to use a regular embossing roll from the viewpoint of productivity. In particular, in order to uniformly apply the colored polymer solution, a flat embossing roll with a grain depth of 70 μm or less is recommended. It's the best.

The heat treatment conditions using the embossing roll should be kept to a level that allows the colored polymer solution to be applied uniformly, as described above; if it is stronger than necessary, it will worsen the creases and texture, and at the same time make the final embossing difficult. and the desired flatness cannot be obtained.

After the heat treatment, a polymer B layer containing a pigment is applied to the surface of the substrate in order to hide spongy spots and embeddings (coagulation spots) on the substrate surface that inevitably occur during substrate manufacturing.

The same polymers as those used in the polymer A layer are used, and among them, a polyurethane elastomer based on diincyanate and having a nitrogen content of 3 to 7% by weight is the best in terms of heat resistance and flexibility.

As the pigment, either an inorganic pigment or an organic pigment can be used, and the former is particularly preferred in terms of hiding power.

The type, color and amount of pigment used should be determined depending on the degree of coagulation spots, the color of the substrate and the desired product, but the amount used should be determined based on the adhesion between the substrate and the polymer B layer, flexibility, etc. It is preferably 1 to 300% by weight.

When a polyurethane distomer is used as the polymer for the polymer B layer, it may contain other polymers in the same way as the polymer A layer, and may also contain stabilizers, gloss adjusters, dyes, blowing agents, etc. It can be used as long as the uniformity of the coating film and the adhesion to the polymer A layer or the polymer C layer are not deteriorated.

The thickness of the polymer B layer is 10% in terms of creases, texture, flexibility, etc.
μ or less, particularly preferably 5 μ or less and 0.1 μ or more.

Furthermore, an easily dyeable polymer C layer is applied so that the desired color can be obtained by dyeing.

Easily dyeable polymers include polyurethane distomers containing polyethylene glycol in the soft segment, nylon, amino acid resins, etc.; Most preferred are polyurethane elastomers having a nitrogen content of 3 to 7% by weight based on diisocyanate.

Other polymers, stabilizers, gloss adjusters, colorants, etc. similar to those used in the polymer A layer and polymer B layer may also be used in the polymer C layer to the extent that they do not impede heat fixability or dyeability. You can also do it.

The thickness of the polymer C layer is desirably 10 μm or less, particularly 5 μm or less and 0.1 μm or more, in view of creases, texture, flexibility, etc.

Next, the surface of the substrate is coated with the following device, preferably for 30 minutes.
By continuously processing for more than a second, the shape is stamped and at the same time only the surface layer is heat-set to obtain a flat surface.

This device has a 120 to 180°C crimping part and a 30 to 120°C peeling part on the same surface, and the temperature gradually decreases from the crimping part to the peeling part, so that the temperature difference in the image area is 20°C or more. It is necessary that the flat metal plate or metal roll surface has a desired grain, that is, a mirror surface or an uneven pattern, and the depth of the uneven pattern is usually 70μ or less to maximize the effect of the present invention. preferred for.

In order to process a substrate operationally using this device, the surface of the substrate is placed against the pressure bonding part of the metal plate or metal roll, pressed with a back roll, etc., and then the temperature is gradually increased while the substrate is pressed without applying pressure. This is done by peeling off after reaching the peeled portion.

When a normal embossing roll is used, even the sponge in the coating layer of the base material is greatly deformed, making it impossible to obtain sufficient flatness and resulting in very poor folding and texture. Since the sponge on the very surface of the coating layer is only slightly deformed, flatness can be obtained without impairing creases or texture.

If the temperature of the crimped part is below 120°C, the contact with the metal plate or metal roll will not be complete (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 deform, resulting in poor creases and texture.

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 bonded portion and the peeled portion.

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 processing substrates that are difficult to press at the crimping section, such as extremely heavy objects or materials treated with softeners, preheat the substrate, metal plate, or metal roll before crimping. It's better.

Finally, dyeing is performed.

For dyeing, dyes that are normally used for dyeing synthetic leather and natural leather can be used, but metal complex dyes are preferred because of their color feel and physical properties. Dyeing can be carried out using a dyeing machine such as , gravure, etc.

Furthermore, finishing treatments such as fabric softener treatment, color and gloss adjustment, and fir processing can be performed as necessary, and the skin sheath sheets obtained in this way have a smooth texture and texture compared to conventional ones. It has very good quality and has a luxurious feel.

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

Hereinafter, the present invention will be specifically explained with reference to Examples.

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

Example 1 A nonwoven fabric made of mixed spun fibers of nylon and polystyrene (mixed weight ratio 1:1) with an N content of 47% made of polybutylene adipate glycol, 1,4-butanediol, and diphenylmethane-4,4'-diisocyanate.
% polyurethane distomer 15%, brown pigment 1%
, a solution consisting of 3% water and 81% dimethylformamide was impregnated, and the same solution was applied on top of this at a solid content of 80%. /m” and contains 35% dimethylformamide 4
After treatment with an aqueous solution at 0° C. for 30 minutes, polystyrene was extracted and removed, solvent removed, and dried to produce a porous substrate (I).

10% of the same polyurethane distomer as above on the base,
A solution consisting of 28% dimethylformamide, 38% acetone, and 24% cyclohexanone is applied to a solid content of 2 μm (polymer A layer), and after drying, a satin pattern is embossed using an embossing roll method under normal conditions. (steam pressure 5 kg/cat, press 1 kg/cst, speed 5 m/min).

Subsequently, a solution consisting of 7% of the same polyurethane distomer, 11% of brown inorganic pigment, 21% of dimethylformamide, 38% of acetone, and 23% of cyclohexanone was applied at a solid content of 1.5μ and dried (polymer B layer). After that, a solution consisting of 7% polyurethane distomer with an N content of 6% consisting of polyethylene glycol, ethylene glycol and hiscyphenylmethane-4,4'-diisocyanate, 20% dimethylformamide, 42% acetone and 31% cyclohexanone was solidified. After coating (polymer C layer) to a thickness of 2μ in minutes, after drying, heat fixation for 90 seconds using an endless metal belt with a mirror surface with a temperature of 150°C at the crimping part and 70°C at the peeling part. , in other words, it was stamped.

The heat fixing is performed by attaching the substrate to a rubber bank roll (
Press it onto the metal belt with a gauge pressure of 2 kg/c4), then move it to the peeling part while keeping it pressed without applying pressure.
Peeling was performed.

Finally, dye using a Taiko type dyeing machine under the following dyeing conditions, dyeing conditions: Dye Niranyl Brown 3R (metal complex salt dye manufactured by Sumitomo Chemical Co., Ltd. KK) 2% wf Bath ratio: 1: 100 Dyeing temperature, Time: Soap at 60℃ for 45 minutes and dry at low temperature to create a leather-like sheet ('
A) was obtained.

As shown in Table 1, the leather-like sheet [Layer A] had good flatness, creases, and color, and had an extremely high-quality feel without inclusions due to coagulation spots on the base.

On the other hand, instead of heat setting using the aforementioned endless metal belt, embossing was performed using an embossing roll with a mirror surface under the conditions of a steam pressure of 3 ky/crA, a press pressure of 2 kg/cat, and a speed of 3 m/min. Leather-like sheet (B) was obtained in the same manner as above.

This product had poor flatness and creases, and had low commercial value.

On the other hand, after sequentially applying the same polymer A layer and polymer C layer to the same substrate [I) as described above without applying the polymer B layer and stamping as described above, the leather-like material was obtained. Sheet [A leather-like sheet [C
] was manufactured.

Like the leather-like sheet (A), this product had good flatness and creases, but severe embedding occurred due to coagulation spots on the substrate and coating spots on the polymer C layer, so it had no commercial value. Ta.

Example 2 Polycaprolactone glycol, ethylene glycol and hisphenylmethane-4.4 on a polyethylene sheet
A solution consisting of 8% polyurethane di-stomer with an N content of 3.8% made of '-diisocyanate, 2% polyvinyl chloride, 1% titanium oxide, and 89% dimethylacetamide was applied to a solid content of 607/m2. The porous film was treated with a 40°C aqueous solution containing 20% dimethylacetamide for 30 minutes, followed by desolvation, peeling from the polyethylene sheet, and drying. A base material (CIT) was manufactured by adhering using Nidistomer.

10% of the same polyurethane distomer as above on the base,
A solution consisting of 28% dimethylformamide, 38% acetone, and 24% cyclohexanone is applied to a solid content of 2 μm (polymer A layer), and after drying, a rough fabric pattern is embossed using an embossing roll method. The test was carried out under the following conditions (steam pressure: 3 kg/crA, press pressure: 1 to 9/crA, speed: 5 m/min).

Next, a solution consisting of 8% of the same polyurethane elastomer used for the coating layer of the substrate [■], 4% of polycyclic organic pink pigment (manufactured by Inu Nisseika Kogyo KK), 18% of dimethylacetamide, 42% of acetone, and 28% of cyclohexanone. was applied to a solid content of 3μ, dried (polymer B layer), and then mixed with polyethylene glycol, polycaprolactone glycol (weight ratio of polyethylene glycol/polycaprolactone glycol = 6/4, ethylene glycol, diphenylmethane-4).・Polyurethane elastomer 7 with a nitrogen content of 4.5% consisting of 4'-diisocyanate
%, a solution consisting of 21% dimethylformamide, 41% acetone and 31% cyclohexanone with a solid content of 2.5%.
After coating and drying (Polymer C layer) so that A device was used to perform heat setting, or stamping.

After that, Irugaran Red 2BL 7% was applied to the surface of this substrate.
A solution consisting of 56% acetone and 37% cyclohexanone was applied by gravure and spray methods, dried, and then subjected to fir processing to produce a leather-like sheet CD).

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

Claims (1)

[Claims] 1. A thin layer of a polymer is applied to a substrate consisting of a fibrous base material and a porous coating layer (polymer A layer), and then heat treated with a flattener embossing roll, and then pigment-containing. A thin layer of polymer (polymer B layer) and a thin layer of easily dyeable polymer (polymer C layer) are sequentially applied, and the temperature of the crimped part is 120°C to 180°C, and the temperature of the peeled part is 30°C to 120°C. ℃ range, and the temperature gradually decreases from the crimping part to the peeling part, and the temperature difference in the image area is 20 ℃ or more. A method for manufacturing a high-quality leather-like sheet, which is characterized by stamping and then dyeing. 2. The manufacturing method according to claim 1, wherein the substrate comprises a porous fibrous base material impregnated with a polyurethane distomer and a porous coating layer of a polyurethane elastomer. 3. Claims 1 or 2 in which a polyurethane nystomer based on diincyanate and having an N content of 3 to 7% by weight is used as the substrate, the polymer A layer, the polymer B layer, and the polymer C layer. manufacturing method. 4. The manufacturing method according to any one of claims 1 to 3, wherein a polyurethane distomer containing polyethylene glycol as a soft segment is used as the polymer C layer. 5. The manufacturing method according to any one of claims 1 to 4, wherein a flat embossing roll having a mirror surface or an uneven pattern with a depth of 70 μm or less is used as the heat treatment device. 6. The manufacturing method according to any one of claims 1 to 5, wherein a flat endless metal plate is used as the device for continuously stamping.