JPS6025264B2 - Laminated body with a pattern on its surface and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laminate having a pattern on its surface and a method for producing the same.

More specifically, the present invention relates to a laminate having a pattern on its surface that can be effectively used as synthetic leather, and a method for producing the same. Synthetic leather is manufactured by forming a leather pattern such as a grain pattern or an embossed pattern on the surface of a synthetic resin sheet, generally a soft trade pinyl chloride resin sheet, by high-frequency embossing.

In this case, if there are two or more vinyl layers, the surface layer is made of a material with a lower melting point than the inner layer, and high frequency processing is performed,
It is stated in Hakama Kosho 51-8 Hei No. 7 that an embossed part with the leather emboss removed can be obtained in good condition in areas other than the skin emboss. However, when using pinyl chloride resin as a material for synthetic leather, it is impossible to avoid disadvantages such as leaching of the plasticizer, loss of strength at low temperatures, and staining of the upper and lower molds used in high-frequency welders. This is essentially impossible, and therefore other synthetic resin materials are being sought as materials for synthetic leather. As a material for synthetic leather, it is absolutely necessary to be able to perform high-frequency embossing processing, but in addition to this, high surface hardness is also required from the viewpoint of wear resistance.

However, since no single type of resin has been found that has both of these properties, the inventors have made efforts to solve these problems by laminating multiple types of resin layers. Then, the skin layer of the laminated sheet such as synthetic leather is formed of a specific resin with high surface hardness, specifically, a Shore hardness of about 50 degrees or more, and the lining layer is formed by applying a high frequency current. It has been found that the above-mentioned problems can be effectively solved by using a sheet made of a specific heated and flexible resin and laminated by heat-sealing or the like. When a high-frequency current is applied to such a laminated sheet while pressing it between the upper and lower electrode plates with the skin layer positioned on the upper mold side of the high-frequency welder, the lining layer is first heated by the high-frequency current. , the heat is transferred to the epidermal layer, and the epidermal layer is embossed with a silicone rubber mold etc. attached to the upper mold.
As a result, an embossed finish is applied to create leather patterns.

Therefore, the high-frequency current generated from the upper mold electrode of the high-frequency welder penetrates through the skin layer to the lining layer, where the lining layer is heated for the first time, so the resin materials forming the skin layer and lining layer are It must have high frequency characteristics. This high frequency characteristic is specified by the value of the dielectric loss factor, which is expressed as the product of the dielectric constant and the dielectric power factor (dissipation tangent), and the dielectric constant and the shielding power factor are determined according to ASTM D-15.
When measured at a frequency of 40.68 MHz by the method specified by , and the skin material has a dielectric loss factor of 1.
Ethylene resins having a surface hardness in the order of 0-3 and a Shore hardness of at least about 50 degrees are selected and used.

Therefore, the present invention relates to a laminate having a pattern on its surface, and this laminate has a lining layer made of an ethylene resin having a product of dielectric constant and dielectric power factor of 3×10-2 or more; It is made of an ethylene resin having a product of dielectric constant and dielectric power factor of the order of 10-3 and a surface hardness of at least about 50 degrees on the Shore hardness, and has an embossed skin layer laminated thereon. .

In order to manufacture such a laminate having a pattern on its surface, a laminate of a lining layer and a skin layer made of ethylene resin each having a dielectric loss factor as described above is pressed between upper and lower electrode plates. This is done by applying a high-frequency current while applying embossing to the epidermal layer. As the ethylene resin forming the lining layer, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate IJ rate copolymer, etc. are used.

Particularly preferred ethylene-vinyl acetate copolymers generally have a vinyl acetate content of about 10 to 45% by weight;
Preferably, about 13 to 30% by weight is used, and its high frequency characteristics vary depending on the frequency, but when the frequency is 40%
．． At 68 MHz, the dielectric constant is approximately 2. Generally speaking, the dielectric power factor is approximately 2.4 to 2.0, and the dielectric power factor is approximately 1.25×1.
0-2 or more, generally about 2.0 to 4.0 x 10-2, and the resultant product of these ratios is about 3 x 10-2 or more, generally about 5 to 10 x 10-2. A value of 2 is used. Ethylene-vinyl acetate copolymers therefore have sufficient high-frequency formability, and such properties are clearly exhibited when the vinyl acetate content is above about 1% by weight, and as the pinyl acetate content increases The high frequency moldability is further improved, but from the viewpoint of other physical properties, it is preferable to keep the pinyl acetate content within about 45% by weight. Polyethylene, polypropylene, ethylene-propylene binary copolymer, ethylene-propylene-gene terpolymer, ethylene-butene can be used within the range that does not impair the body loss rate specified for these ethylene resins. Other resins or rubbery materials such as copolymers and polybutadiene may also be blended and used. In this way, ethylene-vinyl acetate copolymer not only has excellent high-frequency processability, but also has flexibility and elasticity similar to soft vinyl chloride resin and rubber, even though it does not require a plasticizer. It has the characteristic that it does not become hard even at low temperatures like European vinyl chloride resin. In addition, ethylene-vinyl acetate copolymer has excellent film resistance, no ozone aging phenomenon, and exhibits excellent properties such as tear strength, impact strength, and stress cracking properties, and has a specific gravity similar to that of rubber. It has modern properties as a synthetic leather material, such as being more than 30% lighter than vinyl chloride resin. Therefore, it is expected that European grade vinyl chloride resins will be used in various applications in the field of flexible materials, and moreover, they are expected to have better properties than when soft vinyl chloride resins are used. However, since it has a surface hardness of 4 and is easily scratched, there are major limitations on its use as it is, not only for synthetic leather but also for other uses. The same advantages and disadvantages that can be said about ethylene-vinyl acetate copolymer can also be said about ethylene-ethyl acrylate copolymer. Therefore, these ethylene resins that form the lining layer have a high surface hardness, specifically AS.
It has been considered to laminate as a skin layer an ethylene resin having a surface hardness with a Shore hardness of at least about 50 degrees when measured by the method specified by TMD-2240 or JISK-Muscle 01.

Ethylene resins with such surface hardness include:
Resins obtained by neutralizing copolymers of olefins and unsaturated carboxylic acids, or other vinyl compounds with alkali metals, alkali metals, zinc, or organic bases,
In particular, copolymers of ethylene and acrylic acid or methacrylic acid containing metal ion bonds, and saponified copolymers of ethylene and vinyl acetate at a ratio of about 15 to 45% by weight are used. It can also be blended with polyethylene or polypropylene within a proportion that does not impair the specified dielectric loss factor or surface hardness. In addition, when producing high-grade products, thermoplastic polyurethane and the like are also used as blend materials. A copolymer (ionomer) in which metals such as sodium or zinc are ionically bonded has a frequency of 40. Muscle dielectric constant in megahertz is approximately 2.3 to 2. The dielectric power factor is approximately 1 to 4 x 10-3, the dielectric loss factor is on the order of 10-3, and most of the shore hardness values are 60 degrees or higher. The saponified ethylene-vinyl acetate copolymer also has a dielectric loss factor of 10-3 particles and a Shore hardness of 52 to mottled. These ethylene resins, which have a high surface hardness, are naturally scratch-resistant and have good wear resistance, but they are too rigid to be used in the field of flexible materials, and their high-frequency properties make it difficult to use high-frequency molding alone. The problem is that it cannot be applied. However, in order to compensate for the shortcomings of both the ethylene resin that forms the lining layer and the ethylene resin that forms the skin layer, and to take advantage of their advantages, it is possible to combine them to form a laminate, generally a laminate sheet. A sheet with excellent flexibility, high-frequency moldability, and good surface properties is obtained, and this can be effectively used as a sheet for high-frequency embossing processing in synthetic leather materials and the like. This laminated sheet is easy to manufacture because both are made of ethylene resin and can be thermally bonded to each other. When making a sheet, the skin layer resin film or sheet is combined, or
It can be easily manufactured by coating a skin layer resin film or sheet with a lining layer resin. The laminate consisting of the lining layer and the skin layer can have various patterns such as leather patterns, seams, punched holes, and pinking on the surface, so it can be used as a synthetic leather material, etc., but generally is used by lining the lining layer side with fabric such as cloth.

It can be used for a wide variety of purposes, including shoe uppers, handbags, wallets, briefcases, trunks, playmats, belts, golf bags, automobile interior parts, and furniture decorations. Although related to such uses, the ratio of the thickness of the lining layer and the skin layer constituting the laminate is, for example, when an ethylene-vinyl acetate copolymer is used as the lining layer.
It varies depending on the proportion of the pinyl acetate copolymer unit in the copolymer, and when the pinyl acetate unit is 1% by weight, the thickness when using an ionomer as the skin layer is generally about 500 to 700 mm. , about 3-30%, preferably about 5-15% of the laminate sheet up to one thickness thick.
It is preferable to have a ratio within the range of from the viewpoint of flexibility and heat capacity. In addition, in the case of ethylene monovinyl acetate copolymer containing 25% by weight of vinyl acetate units, the ionomer layer can be thinned to about 50 μm, and such laminated sheets can be used in applications where flexibility is important. Can be used. Furthermore, the ethylene-pinyl acetate copolymer can be made into a foam or crosslinked foam by various known methods, and such various foams can also be used as a material for forming the lining layer of the laminate according to the present invention. It can be used as

The rigidity of soft vinyl chloride resin, which has traditionally been used as a material for synthetic leather, is extremely low, and the reality is that even a single sheet of ethylene-vinyl acetate copolymer resin is not as flexible as a European-quality vinyl chloride resin sheet. Therefore, when a laminated sheet is made with an ionomer, it cannot be avoided that the texture differs from that of a soft vinyl chloride sheet in terms of flexibility and rigidity. Therefore, by forming the lining layer with a low-magnification foam of ethylene-vinyl acetate copolymer resin, the rigidity of the laminated sheet can be lowered, the flexibility increased, and the texture can be approximated to that of European pinyl chloride resin sheets. made it possible. In order to obtain such a texture, the proportion of vinyl acetate units in the ethylene monovinyl acetate copolymer must be approximately 14 to several percent by weight, the expansion ratio must be approximately 1.5 to 50 times, and The thickness of one layer of ionomer accounts for approximately 5-10%
It is preferable that it is within the range of . In this way, in a laminated sheet consisting of a lining layer and a skin layer, ethylene-vinyl acetate copolymer or ethylene ethyl acrylate copolymer is used as the material for the lining layer, and the comonomer content of these copolymers is Adjust the ratio of body components, make it into a foam as necessary, use an ionomer or saponified ethylene-vinyl acetate copolymer as the skin layer, and adjust the ratio of the thickness of the lining layer and the skin layer. By adjusting the , a laminated sheet with a texture similar to a soft vinyl chloride resin sheet can be obtained, and since the laminated sheet does not contain a plasticizer, it will not corrode the silicone rubber mold or contaminate other combination substrates. It is lightweight, has excellent cold resistance, has little change in rigidity at low temperatures, and has good adhesion to metals, cloth, etc. for the lining layer.

In the present invention, the laminated sheet is inserted so that its skin layer is positioned on the upper mold side of the high-frequency welder, the lining layer is high-frequency heated through the skin layer, and the heat is transferred to the skin layer. Although the skin layer is embossed, the dielectric loss factor of the skin layer is on the order of 10-3, so it cannot be said that it has good high frequency characteristics, but the thickness of the skin layer is Since it is relatively thin, it does not substantially impede high frequency heating in the lining layer.

In this way, the surface hardness is high and the flexibility is high.
Although a laminate that can be effectively used for synthetic leather and the like can be easily obtained, the present invention also has the following features compared to the prior art. First, in the invention described in the above-mentioned Japanese Patent Publication No. 51-8-7, the surface layer of the plurality of vinyl layers is subjected to high-frequency processing using a material with a lower melting point than the inner layer, so that the surface layer becomes more The phenomenon that the skin layer easily softens or dissolves by high-frequency heating due to its low melting point is utilized, but in the present invention, the bicat softening point of the ionomer or saponified ethylene-vinyl acetate copolymer forming the skin layer is utilized. are about 70-80 qo or about 75-90 qo, respectively.
The softening point of the ethylene-vinyl acetate copolymer forming the lining layer is approximately 50 to 7 pi Embossed patterns etc. are formed neatly.

Secondly, as described in Japanese Patent Publication No. 51-14561, in order to form a pattern with deep unevenness,
It is common practice to form both the upper and lower molds of a high-frequency welder into a male mold and a female mold, and to carve a concave-convex pattern on the opposing surfaces of these two molds. engraved,
If the lower mold is made flat without having a pattern engraved on it, a deep uneven pattern cannot be formed, and therefore only an indistinct pattern is usually obtained.

On the other hand, ionomers have good deep drawability and can be used in a very wide range of drawing conditions, so even if a flat material is used for the lower mold, it is easy to create deep uneven patterns, or in other words, clear leather patterns. It has the effect of being able to be formed in the epidermal layer. Next, the present invention will be explained with reference to examples.

Example 1 Ethylene-methacrylic acid copolymer to which sodium metal was ionically bonded (melt index: 1.2, 40, power yield rate at MHz: 2.2, yield power factor: 2.3×10-3,
Shore hardness: 62 degrees)) and an ethylene-vinyl acetate copolymer (vinyl acetate content: 25% by weight, melt index: 6.0, dielectric constant at 40 MHz, 2.0 dielectric power factor) A two-layer sheet with a lining layer of 3.9×10-2) laminated with a thickness of 450 mm was manufactured by coextrusion processing.

This two-layer sheet is pressed between an upper electrode plate equipped with a silicone rubber mold capable of forming a leather pattern and a flat lower electrode plate, with the skin layer facing upward, and then pressed between the upper and lower electrode plates. Meanwhile, a high frequency current with a frequency of 40.68 MHz was applied for a short time to transfer the leather pattern to the skin layer of the two-layer sheet. When the high-frequency current was turned off and the mold was removed after cooling, the surface of the two-layer sheet was clearly embossed with a leather pattern. When such a sheet was used as a skin and processed into skate shoes, it was found to have sufficient properties to be usable. A product with Frequency 40. Similar results were obtained when a high frequency current with a frequency of 13.56 MHz or 27.12 MHz was used instead of a high frequency current with a frequency of 13.56 MHz.

Comparative Example In the two-layer sheet of Example 1, the ethylene-vinyl acetate copolymer (vinyl acetate content 8% by weight, melt index 1.7, 40.0 MHz, dielectric constant 2.4 dielectric power factor 1.1) The same operation as in Example 1 was repeated except that a lining layer of the same thickness consisting of x10-2) was used.

Although various conditions were changed, such as using high-frequency currents of various frequencies and increasing the application time, it was not possible to create a good pattern on the surface of the two-layer sheet. Example 2 Ethylene-methacrylic acid copolymer with ionically bonded zinc metal (melt index 5.040, dielectric constant 2.3 at seam MHz, dielectric power factor 0.6×10-3, Shore hardness 57 degrees) A skin layer with a thickness of 50 r consisting of ethylene-vinyl acetate copolymer (vinyl acetate content 25% by weight,
Foam (melt index 2.0) (expansion ratio 2.0)
) A two-layer sheet with a lining layer of 750 mm thick was produced by a coextrusion process.

This sheet has good flexibility and surface hardness.
When this two-layer sheet was subjected to high-frequency embossing in the same manner as in Example 1, excellent synthetic leather was obtained. Example 3 A 50 mm thick film made of a completely saponified ethylene-pinyl acetate copolymer (vinyl acetate content 3%, melt index 30) was coated with ethylene-ethyl acrylate copolymer (density 0.901 g). A two-layer sheet consisting of a skin layer and an inner lining layer was obtained by extrusion coating a block with a melt index of 6.0, a dielectric constant of 2.7 at MHz, and a dielectric power factor of 2 × 10-2. .

Claims (1)

[Claims] 1. On a lining layer made of an ethylene resin whose product of permittivity and dielectric power factor is 3×10^-^2 or more at 40.68 MHz, The product with the rate is 40.
A laminated layer having a pattern on the surface, which is made of an ethylene resin having an order of 10^-^3 at 68 MHz and a surface hardness of at least about 50 degrees in terms of Shore hardness, and has a skin layer laminated with an embossed surface layer. body. 2. The laminate according to claim 1, wherein the lining layer is a non-foamed ethylene resin layer. 3. The laminate according to claim 1, wherein the lining layer is a foamed ethylene resin layer. 4 A lining layer of ethylene resin having a value of 3×10^-^2 or more where the product of permittivity and dielectric power factor is 40.68 MHz, and the product of permittivity and dielectric power factor is 40.68 MHz. A laminate consisting of a skin layer of ethylene resin having an order of 10^-^3 and a surface hardness of at least about 50 degrees in terms of Shore hardness is pressed by both upper and lower electrode plates while applying a high frequency current to the skin. A method for producing a laminate having a pattern on its surface, which comprises embossing the layers. 5. The method for producing a laminate according to claim 4, wherein the lining layer is a non-foamed ethylene resin layer. 6. The method for producing a laminate according to claim 4, wherein the lining layer is a foamed ethylene resin layer.