JP3945749B2 - Release sheet - Google Patents

Description

【００４２】
【発明の効果】
以上説明したように、本発明の離型シートの離型層は、長期にわたり優れた耐熱性及び機械強度を有し、２００℃付近の高温で繰り返し処理した場合であっても、その表面の凹凸模様やツヤに変化が生じることがない。したがって、本発明の離型シートをくり返し使用して、均一な品質の合成皮革製品や化粧板等を製造することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a release sheet used for the production of various synthetic leather products such as polyurethane synthetic leather, semi-synthetic leather and polyvinyl chloride leather, and decorative plates, and a method for producing the same.
[0002]
[Prior art]
Conventionally, as a release sheet used for the production of synthetic leather products such as synthetic leather and semi-synthetic leather made of polyurethane resin or vinyl chloride resin, and decorative boards, heat-resistant release paper, heat-resistant polypropylene, Release paper (also referred to as “process paper”) laminated with polyolefin resin such as methylpentene and further embossed is marketed and sold. And after extruding polyurethane resin, polyvinyl chloride resin, etc. on this release paper, transferring the embossed pattern on the release paper surface, and peeling the release paper, various synthetic leather products, decorative boards, etc. It is manufactured.
[0003]
However, when a synthetic leather product is manufactured by repeatedly using this release sheet, since the molding is performed at a high temperature (around 200 ° C.), the embossed pattern and gloss on the surface of the polyolefin resin layer of the release paper change. In some cases, synthetic leather products having the same embossed pattern or gloss cannot be mass-produced.
[0004]
[Problems to be solved by the invention]
The present invention has been made in view of the actual situation, and is a release sheet used for manufacturing various types of synthetic leather products, decorative boards, etc., and is the same even when repeatedly used at a high temperature around 200 ° C. It is an object of the present invention to provide a release sheet capable of producing a synthetic leather product having an embossed pattern and gloss.
[0005]
[Means for Solving the Problems]
As a result of intensive investigations aimed at solving the above problems, the present inventors have devised a release sheet in which a release layer is formed on a base sheet using a resin composition containing a cross-linked polyolefin resin. . And when this release sheet is used, there is no change in the embossed pattern and gloss on the surface of the release layer even if it is repeatedly used at high temperatures, and synthetic leather products having the same embossed pattern and gloss etc. The inventors have found that it can be manufactured with good reproducibility and have completed the present invention.
[0006]
Thus, according to the present invention, there is provided a release sheet having a base sheet and a release layer formed on the base sheet from a resin composition containing a cross-linked polyolefin resin.
[0007]
In the release sheet of the present invention, the release layer is preferably formed from a resin composition having a melt flow rate value of 5 to 40 g / 10 minutes before curing, and a cured product of the resin composition. More preferably, the gel fraction of the cured product is 40% or more.
Moreover, in the release sheet of this invention, it is more preferable that the said release layer has an uneven | corrugated pattern on the surface.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the release sheet of the present invention will be described in detail.
The release sheet of the present invention has a base sheet and a release layer formed from a resin composition containing a cross-linked polyolefin resin on the base sheet.
[0009]
The substrate sheet to be used is not particularly limited as long as it is a sheet or a film-like substrate that can carry a release layer.
Specific examples of substrate sheets include paper substrates such as thin paper, kraft paper, linter paper, medium quality paper, high quality paper, coated paper, art paper, sulfuric acid paper, glassine paper; sheets of polyolefin resin such as polyethylene and polypropylene Or film; sheet or film of vinyl resin such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer; polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, etc. Polyester resin sheets or films of the above; other synthetic resin sheets or films such as polystyrene, acrylonitrile-butadiene-styrene copolymer, cellulose triacetate, cellophane, and polycarbonate. In addition, in the case of a paper base material, the neutral paper which performed neutral papermaking among said paper is preferable since it is excellent in heat resistance.
[0010]
There is no restriction | limiting in particular in the thickness, magnitude | size, etc. of a base material sheet, The thing of predetermined thickness and a magnitude | size can be used according to the use of a release sheet, the kind of base material sheet, etc. For example, when the substrate sheet is a paper substrate, the basis weight amounts are usually 50 to 300 g / ^{m 2,} preferably from 100 to 200 g / ^{m 2,} when the substrate sheet is a sheet or film of synthetic resin The thickness is usually 10 to 500 μm, preferably 50 to 250 μm. Moreover, the continuous sheet | seat shape, the sheet | seat or film wound up by roll shape can also be used as a base material sheet.
[0011]
When using a paper base as the base sheet, use a paper base with anti-curl processing on the back side (the side opposite to the side where the release layer is formed). Is preferred. By applying the anti-curl processing, it is possible to prevent the base sheet from being curled by heat and the release sheet from being deformed. Examples of the anti-curl processing method include a method of applying a synthetic resin such as acrylic resin, polystyrene resin, styrene-butadiene copolymer or laminating a film of polyolefin resin on the back side of the substrate. It is done.
[0012]
The release layer of the release sheet of the present invention is formed from a resin composition containing at least a cross-linked polyolefin resin. By allowing the resin composition to contain a cross-linked polyolefin resin, a release sheet having a release layer having excellent heat resistance and mechanical strength over a long period of time can be obtained.
[0013]
The cross-linked polyolefin resin can be obtained, for example, by cross-linking a polyolefin polymer by a conventional method.
Examples of polyolefin polymers used include ethylene, propylene, 1-butene, 2-methyl-1-butene, 1-pentene, 2-methyl-1-pentene, 1-hexene, and 2,2-dimethyl-1-butene. 2-methyl-1-hexene, 4-methyl-1-pentene, 1-heptene, 2-methyl-1-hexene, 3-methyl-1-hexene, 2,2-dimethyl-1-pentene, 3,3 -Dimethyl-1-pentene, 2,3-dimethyl-1-pentene, 3-ethyl-1-pentene, 2,2,3-trimethyl-1-butene, 1-octene, 2,2,4-trimethyl-1 -Homopolymers of α-olefins such as octene, and copolymers of these α-olefins and other polymerizable monomers.
[0014]
Examples of other polymerizable monomers include vinyl compounds such as vinyl acetate, styrene, acrylonitrile, methacrylonitrile, and vinyl ketone; unsaturated carboxylic acids such as acrylic acid and methacrylic acid; methyl acrylate, ethyl acrylate, acrylic Examples thereof include unsaturated carboxylic acid esters such as acid n-propyl, methyl methacrylate, ethyl methacrylate, and n-propyl methacrylate; unsaturated carboxylic acid amides such as acrylamide and methacrylamide. These polymerizable monomers can be used alone or in combination of two or more.
[0015]
Examples of a method for crosslinking a polyolefin polymer include (i) a method for chemically crosslinking a polyolefin polymer using a radical generator, (ii) a method for radiation crosslinking using an electron beam, etc., and (iii) a molecule. Examples thereof include a method of crosslinking a crosslinked olefin polymer having an unsaturated bond or an alkoxysilane group with heat or water by catalytic action. Among these, the method (iii) is preferable from the viewpoints that there is no substantial limitation on the usable polyolefin-based polymer and that no special and expensive crosslinking equipment is required.
[0016]
The crosslinked olefin polymer used in the above method (iii) contains a polymerizable double bond and / or alkoxysilane group in the molecule, and the polymers are separated from each other by the polymerizable double bond and / or alkoxysilane group. It is a crosslinked polymer. In the present invention, a vinylsilane-modified olefin polymer such as a polymer obtained by graft copolymerization of a vinylsilane compound to a polyolefin polymer or a polymer obtained by random copolymerization of a vinylsilane compound and an olefin is used. preferable.
[0017]
Examples of the vinylsilane-modified olefin polymer include polymers described in JP-B-48-1711, JP-A-59-36115, JP-A-55-9611, JP-A-11-181187, and the like. . More specifically, for example, various vinyl silane-modified olefin polymers commercially available under the trade name of Wrinklon (manufactured by Mitsubishi Chemical Corporation) can be used.
[0018]
Further, an additive can be further added to the resin composition as desired. Examples of additives include antioxidants, light stabilizers, UV absorbers, heavy metal deactivators, metal soaps, epoxy compounds, pigments, dyes, flame retardants, antistatic agents, lubricants, processing aids, Examples include nucleating agents, plasticizers, fillers, and foaming agents.
[0019]
The melt flow rate value (MFR value) of the resin composition before curing is preferably in the range of 5 to 40 g / 10 minutes. By using a resin composition having an MFR value in this range, a release layer having an easy and uniform thickness can be formed. Here, the MFR value (g / 10 minutes) is a value in which a flow rate for 10 minutes is expressed in grams when a thermoplastic resin melted at a constant temperature is extruded from a circular die having a specified length and diameter with a constant load. It is also called a melt index. The MFR value can be measured according to JISK6922-2 (temperature 190 ° C., load 2.16 kg).
[0020]
A release layer can be formed by forming a layer of the resin composition on the base sheet and then curing it. The method for forming the layer of the resin composition on the base sheet is not particularly limited, and a known coating / molding method can be employed. Examples of the coating / molding method include an extrusion molding method. Examples of the extrusion molding method include a blow molding method, an injection blow molding method, a pipe molding method, a film molding method, and a sheet molding method. More specifically, a method of extrusion molding (melt extrusion molding) of a melt of the resin composition on a base sheet using a known molding machine is preferable. Although the molding temperature at the time of extrusion molding depends on the melting temperature of the resin to be molded, it is usually in the range of 100 to 300 ° C, preferably 140 to 240 ° C.
[0021]
In the release sheet of the present invention, the release layer is formed by extruding and curing a mixture obtained by mixing at least one polyolefin polymer and at least one vinylsilane compound onto a base sheet. It can also be formed. According to this method, it is possible to simultaneously form a cross-linked polyolefin resin and cross-link the cross-linked polyolefin resin in the polyolefin polymer.
[0022]
In the production method of the present invention, after the step of forming the resin composition layer, the surface of the resin composition layer is preferably provided with an uneven pattern before the resin composition layer is cured. A release layer having a concavo-convex pattern on the surface can be formed by applying the concavo-convex pattern and then curing it. And the uneven | corrugated pattern can be transcribe | transferred on the surface of synthetic leather products etc. by using the obtained release sheet for manufacture of synthetic leather products etc. The uneven pattern is not particularly limited, and examples thereof include a grain pattern, a stone pattern, a leather pattern, and a wood pattern.
[0023]
As a method for applying the uneven pattern, for example, after forming a layer of the resin composition by extrusion molding on a base sheet, using various known press machines such as flat plate press machine, roll emboss machine, emboss machine, A method of embossing the embossed plate (embossing roll) by shaping the embossed plate (embossing roll) with heat or pressure on the target material, a method of using a roll with a pattern on the cooling roll surface when extrusion molding, etc. Can be mentioned. Moreover, since the hardening of a resin composition advances with progress of time, it is preferable to perform the operation | work which gives an uneven | corrugated pattern within at least 2 to 3 days after hardening at least after forming the layer of a resin composition.
[0024]
The method for curing (also referred to as “crosslinking”) of the resin composition is not particularly limited. For example, (1) a method of standing at room temperature, (2) a method of heating to a predetermined temperature, and (3) a dry gas at a predetermined temperature. And (4) a method of crosslinking in the presence of a silanol condensation catalyst. Among these methods, when a vinylsilane-modified olefin polymer is used, a method using a silanol condensation catalyst is preferable. By using a silanol condensation catalyst, the crosslinking reaction can easily proceed with water or moisture in the air, and a release layer having a desired gel fraction can be formed.
[0025]
As the silanol condensation catalyst to be used, for example, metal carboxylates such as tin, zinc, iron, lead and cobalt, organometallic compounds such as titanate and chelate, organic bases, inorganic acids, organic acids and the like are used. Can do. More specifically, dibutyltin dilaurate, dibutyltin diacetate, dioctyltin dilaurate, stannous acetate, stannous caprylate, lead naphthenate, zinc caprylate, cobalt naphthenate, tetrabutyl ester titanate, titanate Examples thereof include inorganic acids such as tetranonyl ester, ethylamine, dibutylamine, hexylamine, pyridine, sulfuric acid and hydrochloric acid, and organic acids such as toluenesulfonic acid, acetic acid, stearic acid and maleic acid.
[0026]
Specifically, as a method of curing a resin composition using a silanol condensation catalyst, (i) a resin composition layer containing a silanol condensation catalyst is formed on a substrate by extrusion molding. Then, it is exposed to a water atmosphere, or (ii) a layer of a resin composition coated or impregnated with a silanol condensation catalyst is exposed to a water atmosphere. The conditions for exposing the resin composition layer in a water atmosphere are usually in the range of 10 seconds to 1 week at a temperature of room temperature to 200 ° C., preferably a temperature of room temperature to 130 ° C. In the range of 1 minute to 100 hours. Further, immediately after the resin composition layer is formed by the extrusion molding method, the resin composition layer can be simultaneously passed through the water bath and cooled.
[0027]
In order to allow a silanol condensation catalyst to be present in the reaction system when the layer of the resin composition is cured, (a) a method in which the silanol condensation catalyst is previously blended as a master batch obtained by melting and kneading a polyolefin polymer, (b) Examples thereof include a method in which a silanol condensation catalyst is directly blended into a resin as it is produced. The amount of the silanol condensation catalyst used is usually in the range of 0.001 to 10 parts by weight, preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the vinylsilane-modified olefin polymer.
[0028]
Although there is no restriction | limiting in particular in the thickness of the mold release layer formed as mentioned above, Usually, 1-500 micrometers, Preferably it is 5-300 micrometers, More preferably, it is the range of 10-200 micrometers.
[0029]
Further, the gel fraction (crosslinking degree) of the release layer is preferably 40% or more, and more preferably 45% or more. A release layer containing a cross-linked polyolefin resin having a gel fraction of 40% or more exhibits excellent strength over a long period of time, and may cause changes in the uneven pattern, gloss, etc. on the surface of the release layer. Absent.
[0030]
The gel fraction (%) can be determined as follows. (1) About 50 mg of the release layer portion is collected, and the weight of the sample is accurately weighed. This value is A (mg). Next, (2) the sample bubbles are crushed and placed in a test tube, immersed in 10 ml of xylene, and the test tube is left in an oil bath at 120 ° C. for 24 hours. (3) Thereafter, the mixture is filtered through a container having a 200 mesh stainless steel wire mesh, the insoluble portion on the wire mesh is taken out, vacuum dried at 80 ° C. for 4 hours (pressure 10 mmHg), and then the dry weight B (mg ). (4) The obtained A and B are substituted into the formula: gel fraction (%) = (B / A) × 100.
[0031]
The gel fraction after curing of the resin composition is adjusted by changing the graft ratio of the vinyl silane compound of the cross-linked polyolefin resin, the type and amount of the silanol condensation catalyst, and the conditions (temperature, time) for crosslinking. be able to.
[0032]
The release sheet of the present invention can be suitably used as a release paper at the time of manufacturing various synthetic leather products such as synthetic leather, semi-synthetic leather, leather and the like made of polyurethane resin or vinyl chloride resin. For example, on the release sheet of the present invention, a polyurethane resin, an epoxy resin, a vinyl chloride resin or the like is extruded to form a layer of these resins. Various synthetic leather products (leather etc.) with gloss and decorative boards can be mass-produced. Further, the release sheet can be used in a flat state or after being molded into a predetermined shape.
[0033]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The present invention is not limited to the following examples, and the base material, the type of the cross-linked polyolefin resin, the thickness of the resin layer, the curing conditions, etc. can be freely changed without departing from the spirit of the present invention. it can.
[0034]
Example 1
Commercially available cross-linked polypropylene resin composition (trade name: Linkron XPM-800HM, manufactured by Mitsubishi Chemical Corporation, MFR value: 16 g / 10 min) on neutral paper with a thickness of 127.9 g / m ² Using a die extruder, the resin was extruded to a thickness of about 30 μm at an extrusion temperature of about 230 ° C. and laminated to form a resin layer. Then, it was hardened completely by leaving at room temperature for 14 days, and the release sheet of Example 1 was obtained as a release layer.
[0035]
Example 2
Commercially available cross-linked low-density polyethylene resin composition (trade name: Linkron CH-750T, manufactured by Mitsubishi Chemical Corporation, MFR value: 25 g / 10 min) on neutral paper with a thickness of 127.9 g / m ² Using a T-die extruder, extrusion is performed at a temperature of about 220 ° C. to a thickness of about 60 μm (resin layer formation). Immediately after that, embossing is performed with an embossing machine to form a resin layer surface. A leather pattern was applied. Then, it was hardened completely by leaving at room temperature for 14 days, and the release sheet of Example 2 was obtained as a release layer.
[0036]
Example 3
Commercially available cross-linked polypropylene resin composition (trade name: Linkron XPM-800HM, manufactured by Mitsubishi Chemical Co., Ltd., MFR value: 16 g / 10 min) on 127.9 g / m ² neutral paper, T-die extrusion Extrusion is performed to a thickness of about 60 μm at an extrusion temperature of about 220 ° C. using a machine (resin layer formation). At that time, the surface of the resin layer is cooled by a cooling roll with a skin-drawn pattern on the surface. Was pressed to give a leather pattern on the surface of the resin layer. Then, it was hardened completely by leaving at room temperature for 14 days, and the release sheet of Example 3 was obtained as a release layer.
[0037]
Example 4
Instead of the neutral paper 127.9 g / m ^2, contrary to the use of neutral paper 130 g / m ² with a curl prevention layer having a thickness of 5μm acrylic resin on the back surface (the release layer anti-curl layer The release sheet of Example 4 was obtained in the same manner as in Example 1 except that it was formed on the side surface). The release sheet of Example 4 was less curled than the release sheets of Examples 1 to 3, and was excellent in handleability.
[0038]
Comparative Example 1
A commercially available methylpentene polymer (product: TPX, manufactured by Mitsui Chemicals, MFR value: 100 g / 10 min) on neutral paper of 127.9 g / m ² is about 30 μm thick with a T-die extruder. Extrusion was then performed (resin layer formation). Immediately after that, embossing was performed at an extrusion molding temperature of about 220 ° C. using an embossing machine to give a leather pattern on the surface of the resin layer. Then, it was hardened completely by leaving at room temperature for 14 days, and the release sheet of the comparative example 1 was obtained as a release layer.
[0039]
Preparation of leather A polyurethane resin (trade name: Crisbon 7367SL, manufactured by Dainippon Ink Co., Ltd.) was applied to the surface of the release layer of the release sheet obtained in Examples 1 to 4 and Comparative Example 1. And dried at 130 ° C. to obtain a polyurethane layer having a thickness of 30 μm. Furthermore, after heating at 220 degreeC for 2 minutes, it cooled to room temperature and produced the urethane film (leather) by peeling a polyurethane layer.
The release sheets of Examples 1 to 4 and Comparative Example 1 had good peelability.
[0040]
Repeated peelability test of release sheet Leather was prepared by repeatedly using the release sheets obtained in Examples 1 to 4 and Comparative Example 1 five times. The leather handle and gloss prepared using the release sheet first and the leather handle and gloss prepared using the third time were compared and observed visually. As a result, the case where no change was observed was evaluated as ◎, the case where almost no change was observed, ◯, the case where slight change was observed, and the case where clear change was observed were evaluated as ×. The evaluation results are shown in Table 1 below.
[0041]
[Table 1]

[0042]
【The invention's effect】
As described above, the release layer of the release sheet of the present invention has excellent heat resistance and mechanical strength over a long period of time, and even when it is repeatedly treated at a high temperature around 200 ° C., the surface irregularities thereof. There is no change in pattern or gloss. Therefore, the release sheet of the present invention can be used repeatedly to produce uniform quality synthetic leather products, decorative boards and the like.

Claims (4)

  A release sheet having a base sheet and a release layer formed on the base sheet from a resin composition containing a polyolefin-based polymer having an alkoxysilane group in the molecule, A release sheet in which a mold layer is formed by cross-linking a polyolefin polymer contained in the resin composition with water to form a cross-linked polyolefin resin.   The release sheet according to claim 1, wherein the release layer is formed from a resin composition having a melt flow rate value before curing of 5 to 40 g / 10 minutes.   The release sheet according to claim 1 or 2, wherein the release layer is made of a cured product of the resin composition, and the gel fraction of the cured product is 40% or more.   The release sheet according to any one of claims 1 to 3, wherein the release layer has an uneven pattern on the surface.