JPH06218887A - Releasing sheet for shaping and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide releasing sheet having favorable shaping properties and high temperature shape retention and manufacturing method, with which the releasing sheet can efficiently be manufactured. CONSTITUTION:The releasing sheet for shaping concerned is produced by providing laminate layer mainly made of polypropylene, which is the copolymer of propylene and alkenyl silane so as to be turned into the laminate layer by crosslinking the copolymer by one or more kinds of methods selected from the group consisting of irradiation method with light, irradiation method with electron beam and heating method. By employing polypropylene crosslinked with alkenyl silane, the resultant sheet has favorable shaping properties and the shape of the sheet is retained due to its crosslinked structure when the sheet comes into contact with organic solvent-containing paste at elevated temperature, resulting in keeping favorable shape retention and withstanding its repeated use by a large number of times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cast paper, art paper, coated paper, lightly coated paper, paper such as high-quality paper, or a release sheet having a polyolefin resin film or polyester resin film as a support. Among them, the present invention particularly relates to a release sheet for mold making.

[0002]

2. Description of the Related Art A release sheet for patterning is provided with a release layer made of polypropylene resin, silicone resin, alkyd resin on a support such as high quality paper or coated paper, synthetic leather, ceramic, It is used as a release sheet for casting urethane paste, vinyl chloride sol, etc. in the manufacturing process of carbon fiber prepregs, flooring materials, marking films, etc.

The role of the release sheet used for producing synthetic leather is to hold the resin solution such as urethane paste until it is dried and to release the dried resin film. In the case of casting, the release sheet is used. Since the surface shape of is transferred, it also serves as a mold. Required properties of the release sheet are barrier properties that prevent the resin solution from permeating the support, release properties that allow the resin film to be easily peeled off after drying, heat resistance during drying, and the release sheet is used repeatedly. In many cases, it has appropriate tensile strength, tear strength, curl balance, flexibility for preventing the surface of the support from cracking during embossing, scratch resistance, and the like.

In the case of producing a transfer such as synthetic leather having a flat surface property (enamel, mat, etc.), coated paper or cast paper may be used as a support, and the support may be treated with a releasable resin. In the case of producing a transcription product with a mold, the laminate layer mainly composed of polypropylene resin is mainly used for the purpose of reproducibility of particularly minute parts of the mold or to prevent cracking of the support due to sharp irregularities. It is usually provided on the body surface. Such a laminated layer made of polypropylene not only has a releasability to some extent, but even when a release layer such as a silicone resin is provided thereon, the uniform coating property or reduction of the release agent coating amount is required. It is useful in a sense. For example, when the resin forming the synthetic leather is urethane paste,
The drying temperature is used in the range lower than the melting point of polypropylene.

[0005]

When a release sheet having such a patterning is prepared, a laminated base material using polypropylene has heat resistance for urethane paste, but when the release sheet is repeatedly used. The problem is that the mold collapses, the problem that the operating temperature of polypropylene is limited even when trying to improve the production speed of synthetic leather, and the unevenness when embossing because it is difficult to deform as a laminate material. Had a problem that it could not be reproduced completely. Therefore, the problem to be solved by the present invention is to provide a release sheet which has good reproducibility of molding, can be used at high temperature, and does not lose its shape even after repeated use.

[0006]

As a result of earnest research on means for solving the above problems, the present inventors have found the following inventions. That is, in a mold release sheet comprising a support and a laminate layer containing polypropylene as a main component, the polypropylene is a copolymer of propylene and alkenylsilane, and a light irradiation method,
It is an invention of a release sheet for molding, which is a laminate layer cross-linked by at least one method selected from an electron beam irradiation method and a heating method. The thermal xylene extraction gel fraction of the laminate layer is preferably 20% or more. A release agent containing a silicone resin may be mixed in the laminate layer containing polypropylene as a main component, and a release layer containing a silicone resin may be overcoated on the surface of the laminate layer containing polypropylene as a main component. May be. The laminate layer surface of the release sheet having the laminate layer containing polypropylene as a main component can be used after being mirror-finished, matte surface or embossed. Polypropylene, which is the main component of the laminate layer,
In addition to propylene and alkenylsilane, ethylene can be included as a copolymer component.

The mold release sheet of the present invention comprises a step of forming a laminate layer of a copolymer of propylene and alkenylsilane or a terpolymer of propylene, alkenylsilane and ethylene on a support, The surface is subjected to one or more kinds of surface treatment selected from a mirror surface, a matte surface or an embossed surface, and the step of subjecting the laminate layer to one or more kinds of crosslinking selected from a light irradiation method, an electron beam irradiation method and a heating method. It is characterized by being manufactured by combining the respective steps consisting of.

The present invention will be described in detail below. As the polypropylene used in the present invention, moldability is maintained,
From the viewpoint of reproducibility and from the heat resistance during high temperature use, it is a copolymer with alkenylsilane mainly containing propylene or a terpolymer of propylene, alkenylsilane and ethylene. In the polymerized form, any structure such as isotactic, syndiotactic, atactic, etc. may be used. When laminating, general polypropylene, polyethylene and polymethylpentene (T
It is also possible to mix and use other polyolefin resins such as PX). General polypropylene to be mixed and used is not particularly limited, such as homopolymer, copolymer and terpolymer. These unlaminated resins have many non-gel components at high temperature when they are uncrosslinked (almost 100% are non-gel components when uncrosslinked), and they have fluidity in the high temperature region near the melting point, and are hard to mold. Does not hold the type. For the purpose of improving this heat resistance, it is possible to mix a cross-linking agent such as a polyfunctional acrylate with the laminate resin, but generally, such a cross-linking agent has a polar functional group,
When producing synthetic leather or the like, the releasability between the release sheet and the base material to be molded such as synthetic leather is deteriorated.

For laminating the laminate resin of the present invention on a support, generally used melt extrusion dies, T dies, multi-layer extrusion dies and the like are used. The laminating amount is not particularly limited, but is preferably 5 g / m ² or more as a range in which stable laminating can be performed and patterning can be performed.

The inventor of the present invention has earnestly studied the relationship between the moldability of a laminate material mainly composed of cross-linked polypropylene, the heat resistance, the mold storability after high temperature repeated use, and the high temperature non-gel component. When the high temperature non-gel component is in a certain amount or less in the layer, the mold storability after high temperature repetition can be maintained without impairing the moldability. As a method of reducing the high temperature non-gel component, kneading a polyfunctional monomer into the laminate resin,
A method of reacting by heating, a method of kneading a polyfunctional monomer and a sensitizer into a laminate resin and reacting with light, a method of irradiating the laminate resin with light in chlorine gas or acetylene gas to introduce a chloro group or a vinyl group. Then, a method of reacting with a polyfunctional monomer, a method of reacting by plasma discharge in a dilute acetylene gas, a method of peroxidizing the laminate resin with ozone and a reaction with a polyfunctional monomer having an allyl group or an acryloyl group, a laminate resin A method in which a sensitizer such as benzophenone or N-methyl-2-benzoyl-β-naphthiazoline is kneaded, and light irradiation is carried out to react an unsaturated bond in the molecule, or a laminate resin is irradiated with light or γ rays or electrons. Method of graft reaction of radicals generated by radiation with monomers such as acrylic acid, and electron beam irradiation of laminate resin There may be many methods such as a more cross-linking method, but it is not easy to achieve a good balance between mold retention at high temperature and releasability at the time of mold release.

However, the present inventors have found that polypropylene containing alkenylsilane as a cross-linking component not only has good moldability and heat resistance, but also has good releasability when used as a release sheet, and is capable of being repeatedly used at high temperatures. It was found that the mold preservability after use was excellent.

The alkenylsilane used in the present invention is
For example, vinylsilane and vinylalkyl, vinyldialkylsilane compounds such as vinylmethylsilane, vinylethylsilane, vinylpropylsilane, and vinyldimethylsilane, which can be easily copolymerized with an olefin compound generally in the presence of a Ziegler catalyst. . The polymerization ratio of the alkenylsilane is within the range of 0.03 to 5 mol% when copolymerized with the propylene and ethylene components. If the amount of the alkenylsilane is less than this range, the crosslinking effect is not sufficient and the heat resistance and high temperature are high. There is a problem in mold retention, and if it exceeds this range, uniform copolymerization becomes difficult, and the effect of improving releasability and crosslinkability does not become better than a certain limit, which is economically disadvantageous.

In the laminate resin used in the present invention, polypropylene is used as the main component, but the ethylene component is introduced in the form of copolymerizing with the propylene component, or the polyethylene component is introduced in the form of blending with the polypropylene component. This is also preferable from the viewpoint of improving the suitability for lamination. In this case, the molar ratio of the ethylene component to the propylene component is preferably 3: 1 or less. If the ethylene component exceeds this ratio, not only does it not contribute to the effect of improving the suitability for lamination,
This is because the heat resistance may decrease.

The laminated resin used in the present invention preferably has a thermal m-xylene extraction gel fraction of 20% or more. The hot m-xylene extraction gel fraction referred to here is
The ratio of the gel content when the laminate resin was extracted for 12 hours with hot m-xylene at the boiling point is a value obtained by the following method. After separating 1g of laminating resin (amount of laminating resin used) from the release sheet and cutting it into several pieces, the standard maximum diameter is 16-40μ.
m into a glass filter (manufactured by Shibata Kagaku Kikai Kogyo Co., Ltd., G3.5 with pore number), put the glass filter into a sufficient amount of boiling m-xylene and shake for 12 hours to heat. When a component soluble in m-xylene is extracted and then vacuum-dried, the amount of the laminated resin remaining without being dissolved in hot m-xylene (laminating resin remaining amount) is given by the following formula 1
It is the value obtained in.

[0015]

[Equation 1] Gel fraction (%) = (remaining amount of laminating resin (g) / amount of laminating resin used (g)) x 100

As a matter of course, when the laminating resin contains an inorganic substance such as titanium oxide or zinc oxide, or a substance other than the laminating resin, the weight is subtracted from the calculation. Regardless of the type of the laminated resin such as high density or low density, the 12-hour hot m-xylene extraction gel fraction is a value of 1% or less as long as it is measured in an untreated laminated resin film state not subjected to crosslinking. .

In the laminating resin, dyes and pigments such as ultramarine, cobalt violet, calcium carbonate, zeolite, barium sulfate and titanium oxide, antioxidants, optical brighteners, antistatic agents, dispersants, and stabilizers may be added, if necessary. Various additives such as agents and mold release agents can be appropriately combined and added.

When an electron beam is used for crosslinking the laminate resin, the amount of the electron beam to be irradiated is preferably adjusted within the range of about 0.5 to 20 Mrad in the absorbed dose to the laminate resin. At 0.5 Mrad or less, a sufficient irradiation effect cannot be obtained, and even if the electron beam irradiation amount is increased above 20 Mrad, the cross-linking level and heat resistance of the laminating resin hardly change, and especially polypropylene or paper in the laminating resin is used. However, it is not preferable because it deteriorates the film support.

In the present invention, the moldability after repeated use at high temperature is maintained because the gel fraction of the laminating resin forming the mold plays a large role. The fact that the storability of patterning does not depend solely on the superiority or inferiority of the melting property of the laminate resin means that the laminate resin that was clearly effective in the storability of the patterning by electron beam irradiation and the pre-irradiation that had no storability of the patterning It can also be confirmed from the fact that the laminated resin of No. 1 does not substantially change the melting point range in thermal analysis and the heat of fusion per unit weight.

As an electron beam irradiation method, a scanning method, a caten beam method or the like is adopted, and an accelerating voltage for irradiating an electron beam is preferably about 100 to 300 KV. Although the same treatment as electron beam irradiation can be performed using γ-rays, the dose density is generally low, which is not preferable as a manufacturing method. When ultraviolet rays are used for the reaction of the polyfunctional monomer, a photoinitiator and, if necessary, a sensitizer may be blended, but there is a limit in terms of permeability, and the laminate layer is It is desired to be thinner than 45 g / m ² . As a light source when using ultraviolet rays, for example,
A low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, a xenon lamp, a tungsten lamp and the like are preferably used.

During electron beam irradiation, if the oxygen concentration is high, there is a risk of ozone generation, that the decomposition of the polypropylene component is promoted by oxygen, and the radicals generated on the polypropylene surface react with oxygen and are excessive. It is preferable to perform substitution with an inert gas such as nitrogen, helium, carbon dioxide, etc. for the reason that it becomes an oxide and deteriorate the peeling property, and irradiate in an atmosphere in which the oxygen concentration is suppressed to 600 ppm or less, preferably 400 ppm or less. .

In the present invention, in order to improve the adhesion and wettability of the laminate resin layer and the release resin layer, the laminate resin surface may be subjected to a surface treatment such as corona treatment or a subcoat treatment. Good. Further, on the back surface of the release sheet of the present invention, a back coat layer such as anti-curl, anti-static, or release layer can be provided, and the back coat layer includes an antistatic agent, a hydrophilic binder, latex, A hardening agent, a pigment, a surfactant, a pressure-sensitive adhesive, etc. may be appropriately combined and contained.

The release resin used in the present invention is selected from acryloyl group, methacryloyl group, vinyl group, vinylamide group, hydrosilyl group, silanol group, diazo group, acetylene group and thiol group at the molecular end or side chain. Silicone resins (mainly polydialkylsiloxanes) having such functional groups, fluorine-containing resins, alkyd resins, aminoalkyd resins and the like. A reaction initiator, a photoreaction initiator, and a sensitizer can be added to these release resins and used. These release resins can be used alone or in combination of two or more. In addition, other binder components, as long as it does not impair the releasability with the release resin,
Additives such as colorants and antioxidants can be mixed. As the curing mechanism of the release agent, condensation type, addition type, crosslinking type, ring-opening polymerization type reaction and the like are possible.

With respect to the embossing process, any ordinary embossing method such as matched steel embossing, steel / steel embossing, paper / steel embossing, rubber / steel embossing, planographic steel embossing, high pressure embossing, and heat embossing may be used. As a matter of course, the release sheet prepared in the present invention has a smooth surface or a matte surface (matte surface) depending on the surface shape of the chill roll or the cooling roll when laminating is performed, when the mold is not applied. can get.

As the support used in the present invention, in addition to plain paper base paper, coated paper such as glassine paper, high-quality paper, art paper, coat paper, cast paper and synthetic resin film,
Synthetic paper and the like are used, but natural pulp paper containing wood pulp of softwood pulp, hardwood pulp, and mixed wood of softwood as the main component is advantageously used. The thickness of the base paper is not particularly limited, but a smooth one is preferable, and its basis weight is preferably 30 to 300 g / m ² .

In the method of the present invention, the base paper containing natural pulp as a main component, which is advantageously used, may contain various polymer compounds and additives. For example, starch, starch derivatives (cationized starch, phosphate esterified starch, oxidized starch, etc.), polyacrylamide, polyvinyl alcohol, polyvinyl alcohol derivatives (complete saponification, partial saponification, carboxy modification, cation modification, and various other modifications). Polyvinyl alcohol), gelatin (alkali treatment, acid treatment, various modified gelatin), etc., dry paper strength enhancer, natural polymer polysaccharides such as star gum and alginic acid derivatives, higher fatty acid metal salts, rosin derivatives, dialkyl ketones, alkenyls or alkyls. Sizing agents such as succinic anhydride, epoxidized higher fatty acid amide, organic fluoro compound, dialkyl ketene dimer emulsion, polyamide polyamine epichlorohydrin resin,
Wet paper strength enhancer such as melamine resin, urea resin, epoxidized polyamide resin, stabilizer, pigment, dye, antioxidant,
Fluorescent whitening agents, various latexes, inorganic electrolytes (sodium chloride, sodium sulfate, sodium phosphate, calcium chloride, lithium chloride, magnesium chloride, magnesium sulfate, barium chloride, etc.), pH adjusters, sulfuric acid bands, aluminum chloride, etc. Agents, fillers such as calcium carbonate, kaolin, talc and clay, and additives such as organic conductive agents can be appropriately combined and contained. These contents may be dispersed in the pulp slurry at the papermaking stage, or may be added at the tab size after papermaking,
Further, the solution may be applied with various coaters.

[0027]

The release sheet according to the present invention has a polypropylene laminate layer having a thermal m-xylene extraction gel fraction of 20% or more cross-linked with alkenylsilane.
The mold can be easily applied to the release sheet, and the mold does not collapse even when it is repeatedly used at high temperature. Therefore, good mold transfer property can be obtained repeatedly.

[0028]

The present invention will be described in detail below with reference to examples, but the contents of the present invention are not limited to the examples.

Example 1 A commercially available process paper base paper (manufactured by Mitsubishi Paper Mills, process paper base paper 125 g / m ² ) was used as a base paper for a release sheet. After the surface was corona-treated, melt extrusion lamination was performed with a resin of a copolymer of propylene and vinylsilane (vinylsilane was 1 mol% of the total) at a laminating amount of 25 g / m ² . The laminated base material was textured with a paper / steel embossing roll. Next, this base material was irradiated with an electron beam at an acceleration voltage of 250 kv so that the absorbed dose was 5 Mrad to crosslink the laminate resin, thereby obtaining a release sheet for embossing the embossed surface. The hot m-xylene extraction gel fraction of the laminate resin after this electron beam irradiation was 80%. On the obtained release sheet for patterning, urethane paste for synthetic leather (main ingredient: trade name Chris Bonn 5516S, manufactured by Dainippon Ink and Chemicals, color material 1
5%, solvent; contains methyl ethyl ketone 30%),
After drying at 110 ° C., an adhesive urethane resin paste (main agent, trade name Crisbon 4110, manufactured by Dainippon Ink and Chemicals, Inc., isocyanate component; Crisbon NX 10%, accelerator; Crisbon Axel HM 3%, solvent; DMF (Including 15%), was laminated on the urethane resin-impregnated base fabric, heat-dried at 120 ° C., and further cured at 40 ° C. for 2 days, and then separated from the release sheet to obtain synthetic leather.
Using the release sheet after use, the same synthetic leather was prepared 5 times to obtain a release sheet after use.

Example 2 The same process as in Example 1 was carried out by using a terpolymer of propylene, ethylene and vinylsilane (propylene: ethylene = 95: 5 in molar ratio, 0.05% by mole of vinylsilane as a whole) on a paper base paper. The resin was melt-extruded and laminated using a mirror-like cooling roll at a laminating amount of 25 g / m ² . The laminated base material was irradiated with ultraviolet rays from a medium-pressure mercury lamp to cross-link the laminating resin to obtain a release sheet for imprinting a mirror surface. The hot m-xylene extraction gel fraction of the laminate resin after irradiation with ultraviolet rays was 20%. Synthetic leather was prepared in the same manner as in Example 1.

Example 3 5% by weight of low density polyethylene was added to the same resin as in Example 1, a solventless thermosetting silicone resin (manufactured by Toray Silicone, trade name BY14-407) and a low temperature curing catalyst. (Brand name BY14-408CAT, 1% based on the silicone resin) was mixed in a weight ratio of 1%, and melt extrusion lamination was performed using a cooling roll as a matte surface. The laminated base material was cured at 80 ° C. for 1 day to be crosslinked to obtain a release sheet for imprinting the matte surface. The heat m-xylene extraction gel fraction of the laminate resin after the heating and curing was 40%. Synthetic leather was prepared in the same manner as in Example 1.

Example 4 As a laminating resin, a copolymer of propylene and vinyl silane (vinyl silane is 0.5 mol% of the whole) resin is used.
A biaxially stretched film having a thickness of 0 μm was produced. The film was textured with a paper / steel embossing roll. As the base paper for the release sheet, commercially available process paper base paper (made by Mitsubishi Paper Mills, process paper base paper 125 g / m ² ) is used, and electron beam curable resin (made by Toagosei Chemical Industry Co., Ltd., Aronix M1210 and M113) is used. Weight ratio 7: 3 mixture)
Was applied with a gravure roll in an amount of 20 g / m ² and laminated with a patterned film, and at an acceleration voltage of 250 kv,
Electron beam irradiation was performed so that the absorbed dose was 5 Mrad to obtain a mold release sheet for the embossed surface. The hot m-xylene extraction gel fraction of the laminate resin after this electron beam irradiation was 75%. Synthetic leather was prepared in the same manner as in Example 1 using the obtained release sheet for patterning.

Example 5 The same process as in Example 1 A base material paper was melt-extruded with a resin of a copolymer of propylene and vinylsilane (0.01 mol% of the total amount of vinylsilane) at a laminating amount of 25 g / m ^2. I did. On the laminated base material,
Ultraviolet irradiation was performed with a medium-pressure mercury lamp to crosslink the laminate resin, and a release sheet for imprinting a mirror surface was obtained. The thermal m-xylene extraction gel fraction of the laminate resin after irradiation with ultraviolet rays was 10%. Synthetic leather was prepared in the same manner as in Example 1.

Example 6 Same process as in Example 1 Paper base paper was melt-extruded and laminated with a resin of a copolymer of propylene and vinyl silane (vinyl silane was 2 mol% of the total) at a laminating amount of 25 g / m ² . . Next, this substrate was irradiated with an electron beam at an accelerating voltage of 250 kv so that the absorbed dose was 5 Mrad to crosslink the laminating resin to obtain a crosslinked laminating substrate. Using a paper / steel embossing roll, the crosslinked laminate base material was set to a high processing temperature and the leather grain was imprinted to obtain an embossed embossing release sheet. The hot m-xylene extraction gel fraction of this crosslinked laminate resin is 85.
%Met. Synthetic leather was prepared in the same manner as in Example 1.

Comparative Example 1 As the base paper for the release sheet, the same process paper base paper as in Example 1 was used. After corona treatment on the surface, melt extrusion laminate with homopolypropylene 25g / m
A laminating amount of ² was used. The hot m-xylene extraction gel fraction of this polypropylene was 1%. Molding was performed in the same manner as in Example 1, and the obtained release sheet was used to prepare synthetic leather in the same manner as in Example 1.

Comparative Example 2 In Comparative Example 1, after laminating and patterning,
A mold release agent was obtained in the same manner as in Comparative Example 1 except that the electron beam irradiation was performed at an acceleration voltage of 250 kv so that the absorbed dose was 5 Mrad. The hot m-xylene extraction gel fraction of the laminate resin after this electron beam irradiation was 0%. Using the obtained release sheet, a synthetic leather was prepared in the same manner as in Example 1.

Comparative Example 3 As the base paper for the release sheet, the same process paper base paper as in Example 1 was used. After the surface was subjected to corona treatment, melt extrusion lamination with a copolymer resin of propylene and ethylene (molar ratio: 95: 5) was performed at a laminating amount of 25 g / m ² . The laminated base material was irradiated with ultraviolet rays from a medium-pressure mercury lamp to obtain a release sheet for mirror-shaped imprinting. The thermal m-xylene extraction gel fraction of the laminate resin after ultraviolet irradiation was 1%. Synthetic leather was prepared in the same manner as in Example 1.

The release sheets obtained in Examples 1 to 6 and Comparative Examples 1 to 3 were subjected to the following tests.
The results are shown in Table 1.

[Mold storability] In each sample, 2 cm squares of the same handle portion of the release sheet prepared were repeatedly used in Examples and Comparative Examples.
Analyzing with a three-dimensional roughness measuring device under the conditions of 500 points sampling in X direction and 500 lines sampling in Y direction to obtain ten-point average roughness SRz, maximum height SRma, and maximum peak height SRp, and corresponding moldability before use. Was expressed as a ratio (%) to the parameter. The mold storability was expressed as the average value of the ratio of these three parameters. The higher this value, the better the mold storability.

[Repeatability] For each sample, the peel strength at the first peeling of the synthetic leather and the peel strength at the final peeling of the synthetic leather were compared, and the results are shown as a ratio. The closer this value is to 100%, the smaller the change in peel strength due to repeated use.

[High Temperature Usability] A urethane leather paste for synthetic leather was applied to the obtained mold release sheet to prepare synthetic leather. In order to evaluate the usability at high temperature, the drying temperature of the urethane paste in Example 1 was increased by 20 ° C. That is, on the obtained mold release sheet, urethane paste for synthetic leather (main ingredient: trade name Chris Bonn 5516)
S, manufactured by Dainippon Ink and Chemicals, Inc., coated with 15% coloring material, solvent; containing 30% of methyl ethyl ketone) and dried at 130 ° C., then adhesive urethane resin paste (main ingredient: Crisbon 4110, trade name, manufactured by Dainippon Ink and Chemicals, Isocyanate component; 10% of Crisbon NX, accelerator: 3% of Crisbon Axel HM, solvent: 15% of DMF) are applied and overlaid with the urethane resin-impregnated base fabric to form 14
After heat-drying at 0 ° C. and further curing at 40 ° C. for 2 months, it was separated from the release sheet to obtain a synthetic leather. Using the release sheet after use, the same synthetic leather was prepared 5 times to obtain a release sheet after use. Sufficiently typed synthetic leather can be obtained even after the 5th use, and when the peelability is not a problem, the evaluation is excellent. When the moldability deteriorates, the high-temperature usability is judged as being evaluated as normal, and when the number of times of use is 2 times or less, the moldability is deteriorated or the peelability is deteriorated as poor evaluation.

[0042]

[Table 1]

Evaluation Since the release sheets prepared in the examples are laminates of polypropylene containing an alkenylsilane component, even if the same embossing roll is used, it is possible to laminate only polypropylene or a copolymer of propylene and ethylene. Compared with a certain comparative example, the mold preservability is good and the mold can be repeatedly used without losing its shape. The change in peel strength due to repeated use is also sufficiently small. It also withstands high temperatures and enables high-speed production of synthetic leather.

[0044]

As is clear from the evaluation of the present invention, the method according to the present invention makes it possible to supply a release sheet which is excellent in mold preservation and repeatability at high temperature use and has a great industrial value. is there.

Claims (6)

[Claims] 1. A mold release sheet comprising a support and a laminate layer comprising polypropylene as a main component, wherein the polypropylene is a copolymer of propylene and alkenylsilane, and a light irradiation method or electron beam irradiation is used. A release sheet for patterning, which is a laminate layer cross-linked by at least one method selected from a heating method and a heating method. 2. The mold release sheet according to claim 1, wherein the laminate layer has a thermal m-xylene extraction gel fraction of 20% or more. 3. The mold release sheet according to claim 1, wherein a release agent containing a silicone resin is mixed in the laminate layer. 4. The mold release sheet according to claim 1, wherein the laminate layer has at least one surface selected from a mirror surface, a matte surface and an embossed surface. 5. The mold release sheet according to claim 1, wherein the polypropylene is composed of a terpolymer in which ethylene is added to propylene and alkenylsilane. 6. A step of providing a laminate layer comprising polypropylene containing alkenylsilane as a copolymer as a main component on a support, a mirror surface, a matte surface, or at least a laminate layer surface of the support provided with the laminate layer. Is a process in which one or more types of surface processing selected from embossed surfaces are performed,
A method for producing a release sheet for imprinting, which comprises producing each of the laminate layers in combination with each step comprising a step of applying one or more kinds of crosslinking selected from a light irradiation method, an electron beam irradiation method and a heating method.