KR20160076210A - Process for the preparation of synthetic leather - Google Patents

Abstract

The present invention relates to a method for manufacturing a synthetic leather to manufacture a synthetic leather with excellent fouling resistance, adhesive properties and durability. The method comprises the following steps: (a) a first coating step of knife-coating, on a release film, a first coating solution containing a first liquid silicone rubber (LSR) with a viscosity of 100 or more, a stretchability of 300% or more, and a Shore hardness (shore A) of 50 or more; (b) a second coating step of knife-coating, on the release film coated by the first coating solution, a second coating solution containing a second LSR with a viscosity of 100 or more, a stretchability of 300% or more, and a shore A under 50; (c) a bonding step of bonding the release film coated by the second coating solution to a synthetic leather and hardening the same by drying; and (d) a release step of releasing the release film from the synthetic leather bonded to the release film.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention provides a method for producing synthetic leather using a silicone rubber coating solution.

Polyurethane and polyvinyl chloride are conventionally used as coating materials for producing synthetic leather.

However, when synthetic leather is produced by using a coating material made of polyurethane, an organic solvent such as dimethylformamide or methyl ether ketone is used. As a result, environmental problems have occurred, flexibility has changed according to temperature, and hydrolysis resistance to water There is a problem such that it is weak. Therefore, there has been developed a technique using an aqueous dispersion type polyurethane that does not contain an organic solvent, but it has been difficult to exhibit poor processability and excellent physical properties.

Korean Patent Laid-Open Publication No. 2003-0095872 discloses a method for producing synthetic leather using liquid silicone rubber, but the synthetic leather produced by this method does not satisfy rigorous properties such as flame retardancy and smoke density required for aircraft or ship interior materials And other adhesive strengths did not satisfy the required physical properties of the product.

Korean Patent No. 1381914 discloses a method for producing synthetic leather using liquid silicone rubber having different properties. However, the synthetic leather produced by this method is also poor in adhesiveness and durability, so that there is a problem that the bar material is easily damaged when it is processed or used.

Korean Patent Publication No. 2003-0095872 Korean Patent No. 1381914

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a process for producing synthetic leather excellent in physical properties for various uses and excellent in adhesion and durability, and synthetic leather produced by the process.

(A) a first silicone rubber (LSR) having a viscosity of 100 or more, a elongation of 300% or more, and a Shore Hardness (shore A) of 50 or more A first coating step of knife-coating the releasing paper with a first coating liquid to form a first coating liquid; (b) a second coating solution comprising a second silicone rubber (LSR) having a viscosity of 100 or more, a elongation of 300% or more and a Shore hardness of less than 50, and a second coating step; (c) a dipping step in which the releasing paper coated with the second coating liquid is poured with a cloth, followed by drying and curing; And (d) peeling the releasing paper from the fabric to which the releasing paper is adhered.

Another embodiment of the present invention further includes a surface treatment step of (c) after the drying step, treating the surface on which the release paper has been peeled off with a silicone surface coating agent.

In another embodiment of the present invention, the fabric is woven from at least one fiber selected from the group consisting of aramid fibers, oxidized polyacrylonitrile fibers, shrinkable fibers, spandex, polyester fibers and nylon in the step (c) Lt; / RTI >

Another embodiment of the present invention provides a synthetic leather produced by any one of the above methods.

According to the present invention, it is possible to produce a synthetic leather which is environmentally friendly, suitable for various uses, and excellent in stain resistance, adhesion and durability, without using a plasticizer or a solvent.

One embodiment of the present invention is directed to a method of forming a coating comprising: (a) a primary coating step; (b) a secondary coating step; (c) a fusing step; And (d) a peeling step. Each step will be described in detail below.

(1) primary coating step (release paper coating step)

The first step is knife coating the release paper with the first coating liquid.

For this purpose, a first coating liquid containing a first silicone rubber having a viscosity of 100 or more, a elongation of 300% or more, and a Shore Hardness (Shore A) of 50 or more is first prepared.

The first silicone rubber to be used in one embodiment of the present invention is not particularly limited. For example, dimethylsiloxane having a dimethylvinyl end group, methylvinylsiloxane having a dimethyl vinyl end group, methylhydrogensilonic acid having a dimethyl end group And the like.

The first silicone rubber is basically a liquid rubber in which a vinyl group and a methylhydrogen group are cured by an addition reaction under a platinum catalyst. The reason for using the addition type liquid rubber in this way is that water-miscible condensation type rubbers generate by-products such as hydrogen, water, alcohol, acetic acid and the like depending on the crosslinking agent used in the condensation reaction.

Aluminum hydrate, titanium dioxide, silica and the like may be further added to the first coating liquid to improve heat resistance and flame retardancy.

As the first coating liquid used for the synthetic coating layer, a first silicone rubber having an elongation of 300% or less and a Shore hardness of 50 or more has been used, but the adhesiveness of the final product is poor and durability is poor. However, in one embodiment of the present invention, this problem is solved by using a silicone rubber having a viscosity of 100 or more, a elongation of 300% or more and a Shore hardness of 50 or more as the first coating liquid. The first coating liquid is excellent in viscosity because of its excellent viscosity, stretchability and relatively high density.

Then, the primary coating solution is coated on the release paper to perform the primary coating. There is no limitation on the coating method, but knife coating is preferable for engraving patterns.

After the first coating, it is first cured and dried in a chamber of 80 to 170 degrees Celsius. If the curing drying temperature is too high, the release paper may be damaged. If the curing drying temperature is too low, it takes a long time to cure and dry. A release paper on which the first coating layer was formed by the primary coating was prepared. The first coating layer produced in the above step serves as a skin of synthetic leather.

(2) Second coating step (binder coating step)

The second step is to coat the second coating liquid on the first coating layer of the primary coated release paper.

To this end, a second coating liquid containing a second silicone rubber (LSR) having a viscosity of 100 or more, an elongation of 300% or more, and a Shore hardness of less than 50 is prepared. The second coating liquid may contain silicone rubber in the same manner as the first coating liquid, but silicone rubber having different Shore hardness and viscosity as described above should be used.

Then, a secondary coating is coated on the primary coated release paper to perform a secondary coating. There is no limitation on the coating method, but knife coating is preferable for engraving patterns. After the first knife coating and then the second knife coating again, you can engrave different patterns, that is, two tone patterns.

And a second coating layer, a first coating layer, and a releasing paper are laminated in this order by a secondary coating. The fabric is then laminated to the second coating layer prepared in the above step in a subsequent step.

The first coating step and the second coating step are generally carried out separately, but may proceed to a continuous process.

(3) Step of peeling and releasing the fabric

In the next step, the release paper coated with the second coating liquid is dampened with a fabric and dried in a chamber of 80 to 170 degrees centigrade for curing.

As the fabric, those woven from at least one kind of fiber selected from the group consisting of aramid fiber, oxidized polyacrylonitrile fiber, shrinkable fiber, spandex, polyester fiber, nylon and rayon can be used. The fabric is selected depending on the application. For example, amide lead fiber, oxidized polyacrylonitrile fiber, shrinkable fiber and the like are used for airplanes and ship interior materials, and for the automobile, furniture and sundry interior materials, polyester, nylon, rayon Etc. are used.

Then, the release paper is peeled off from the primary coating layer of the fabric having the release paper, thereby obtaining a synthetic leather coated with the silicone rubber surface. A double-coated fabric is formed by laminating the fabric, the second coating layer and the first coating layer in the order of fabric release and release paper peeling.

(4) Surface treatment step

This step is a step of treating the surface of the release paper, that is, the surface of the primary coating layer, with the silicone surface coating agent. In one embodiment of the present invention, the use of the silicone rubber having a viscosity of 100 or more as the first coating liquid may cause a problem of low workability due to high viscosity, but the workability can be improved by surface treatment with a silicone surface coating agent as described above . Through these surface treatment steps, the properties or texture of the synthetic leather surface can be controlled.

(5) Upper coating step

This step is a step of coating again on the secondary coating layer of the surface treated fabric. This step proceeds for the purpose of coating color or improving abrasion. As the upper coating, for example, a gravure roll coating method may be used. The upper coated fabric is again dried and cured in a hot air oven at a temperature of 100 to 220 degrees Celsius to finally produce silicone synthetic leather.

The silicone synthetic leather laminated in the order of fabric-second coating layer-first coating layer-upper coating layer is prepared by surface treatment and top coating step.

In the present invention, the curing conditions may vary depending on the amount of coating, the length of the chamber, and the like.

The synthetic leather produced as described above can be used for various purposes depending on the kind of fabric to be applied. For example, it can be used for airplane, ship interior material, interior material for automobile, furniture and other interior.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following embodiments are only illustrative of the present invention, and thus the scope of the present invention is not limited thereto.

≪ Example 1 >

(1) Primary coating step

First, 100 parts by weight of LCF 8500 A (Dow Corning), 100 parts by weight of LCF 8500 B (Dow Corning), 0 to 30 parts by weight of 245 Fluid (Dow Corning) Of 350% and a Shore hardness of 66 was prepared.

Then, the primary coating solution was knife coated on the release paper in an appropriate amount (50 to 200 g / m < 2 >) to perform primary coating.

The primary coating was then cured and dried in a hot air oven at 130 ° C for 5 minutes. Through this, a release paper having a primary coating layer was obtained.

(2) Second coating step

The secondary coating solution was coated on the primary coating layer of the primary coated release paper.

To this end, 100 parts by weight of LCF 8400 A (Dow Corning), 100 parts by weight of LCF 8400 B (Dow Corning), 0 to 20 parts by weight of 245 Fluid (Dow Corning) , A elongation of 900% and a Shore hardness of 29 was prepared.

Then, the second coating solution was coated on the hardened release paper by coating the first coating solution in an appropriate amount (100 to 300 g / m < 2 >) to perform secondary coating. Through this, a release paper on which a secondary coating layer and a primary coating layer were formed was obtained.

(3) Step of peeling and releasing the fabric

The release paper coated with the second coating solution was dampened with a fabric and dried in a hot air oven at 140 DEG C for 5 minutes to cure. Then, the release paper was peeled off from the primary coating liquid layer to obtain a synthetic leather having the silicone rubber coated on its surface. The release paper is laminated in the order of the second coating layer-the first coating layer-release paper in the order of fabric-second coating layer-first coating layer.

(4) Surface treatment step

100 parts by weight of SL-5060 base, 20 parts by weight of SL-5060 HD hardener, 5 parts by weight of SL-3000 catalyst (Dow Corning), remaining amount of 245 Fluid (Dow Corning) / IPA and modifier The synthetic leather having the release paper peeled off was surface-treated.

≪ Comparative Example 1 &

100 parts by weight of LCF 8300 A (Dow Corning), 100 parts by weight of LCF 8300 B (Dow Corning), and the remaining pigment were blended in the primary coating (release paper coating) stage to obtain a coating having a processing viscosity of 25 Pa · s and a elongation of 230% Synthetic leather was obtained in the same manner as in Example 1, except that a silicone primary coating solution having a Shore hardness of 68 was prepared.

The main components of the primary coating layer and the secondary coating layer of each of the synthetic leather prepared in Example 1 and Comparative Example 1 are shown in Table 1 below.

Example 1 Comparative Example 1 The primary coating layer LCF 8500 AB LCF 8300 AB Second coating layer LCF 8400 AB LCF 8400 AB

The physical properties of the primary coating layer and the secondary coating layer of each of the synthetic leather prepared in Example 1 and Comparative Example 1 are shown in Table 2 below.

Example 1 Comparative Example 1 Working viscosity
(Pa · s) Elongation
(%) Shore hardness Working viscosity
(Pa · s) Elongation
(%) Shore hardness The primary coating layer 180 350 66 25 230 68 Second coating layer 210 900 29 210 900 29

<Experimental Example>

The durability of each of the synthetic leather products manufactured by Example 1 and Comparative Example 1 was tested. Experimental results show that the synthetic leather produced by the comparative example 1 has problems such as the bursting of the bar material when sewing, but the synthetic leather produced by the example 1 does not have such a problem.

Claims (4)

(a) a primary coating which knife-coats the releasing paper with a first coating liquid containing a first silicone rubber (LSR) having a viscosity of 100 or more, a elongation of 300% or more, and a Shore Hardness (Shore A) step;
(b) a second coating solution comprising a second silicone rubber (LSR) having a viscosity of 100 or more, a elongation of 300% or more and a Shore hardness of less than 50, and a second coating step;
(c) a dipping step in which the releasing paper coated with the second coating liquid is poured with a cloth, followed by drying and curing; And
(d) a peeling step of peeling the release paper from the fabric to which the release paper is adhered;
&Lt; / RTI &gt; The method according to claim 1,
And (c) after the drying step, a surface treatment step of treating the release surface of the release paper with a silicone surface coating agent. The method according to claim 1,
Wherein the fabric is woven from at least one fiber selected from the group consisting of aramid fibers, polyacrylonitrile fibers, shrinkable fibers, spandex, polyester fibers and nylon in step (c). A synthetic leather produced by the method of any one of claims 1 to 3.