JPH11969A - Release sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a curl of a pressure sensitive sheet good while a printing aptitude of a non-release agent surface of a release sheet is excellent by a method wherein a primer coat agent layer containing (meth) acrylate ester copolymer is formed on one side surface of orientation treated synthetic paper, and a silicone release agent layer is provided on the primer coat layer. SOLUTION: As a base material, a multi layer structure is provided, and orientation treated polypropylene synthetic paper of 80 μm thickness is used. After coating 5 g/m<2> of copolymer resin emulsion of ethylacrylate and methyl(meth)acrylate as a primer coat agent on a pearl surface of the base material with bar coating, a primer coat agent layer is formed by drying for 1 min in an oven at 100 deg.C. Successively after coating 0.2 g/m<2> of silicone release agent on the primer coat agent layer with bar coating, a release agent layer is formed by drying in an oven at 120 deg.C for 1 min to obtain a release sheet. Thereby, the release agent layer can be formed without obstructing curing of the silicone release agent by nitrogen compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a release sheet used in combination with an adhesive sheet or the like.
More specifically, the surface base material is suitable for application to an adhesive sheet made of a plastic film such as polyester, polypropylene, or polyvinyl chloride, or a metal foil adhesive sheet made of a surface base material made of aluminum foil, copper foil, or the like. It relates to a release sheet.

[0002]

2. Description of the Related Art In pressure-sensitive adhesive sheets and labels,
For the purpose of protecting the pressure-sensitive adhesive layer, attaching a label or supporting at the time of printing, etc., laminating a release sheet on them has been performed. Conventionally, as this release sheet, one side of high-quality paper, kraft paper, or the like, a silicone resin, alkyd resin, A release sheet coated with a release agent such as a silicone alkyd resin or a polyvinyl carbamate resin, or a release sheet coated directly on one surface of glassine paper with the release agent is used.

[0003] However, since these release sheets undergo dimensional expansion and contraction due to environmental humidity changes, plastic films of polyester, polypropylene, polyvinyl chloride, etc., whose dimensional changes are small due to environmental humidity changes, are used as surface substrates. The pressure-sensitive adhesive sheet using a metal foil or a metal foil has a problem that a difference in elongation and contraction between the surface base material and the release sheet occurs due to a change in the humidity of the external environment, and remarkable curling occurs.

[0004] The occurrence of such curl can be caused by printing, die-cutting, sheet-cutting of an adhesive sheet, and processing into labels, stickers, sheets, and the like in each process. In addition to causing irregularities in the sheet, it also causes the floating or tunnel between the surface base material and the release sheet. Therefore, in order to correct the curl of the pressure-sensitive adhesive sheet, a decurler process in which the pressure-sensitive adhesive sheet is sharply bent in a direction opposite to the curl,
Methods of performing steam damping treatment or the like for preventing curling by humidification have been proposed, but these methods have problems such that the steps are complicated and the effect is not long lasting.

[0005] In order to solve such a problem, a release agent is applied to one surface of a release sheet substrate after a base treatment for preventing penetration of the release agent and obtaining smoothness is performed.
Further, a release sheet in which the other surface of the release sheet substrate is subjected to a moisture-proof treatment is used. That is, a polyolefin resin is laminated on one surface of a release sheet substrate, a release agent is applied thereon, and an extruded laminate layer of a polyolefin resin or a polyolefin resin is formed on the other surface (back surface) of the release sheet substrate. By providing a moisture-proof coating layer containing a polymer resin such as vinylidene chloride or polyacrylate resin as a main component by coating or impregnating, by preventing moisture from entering and exiting from the back surface of the release sheet substrate, It is known that the paper is prevented from curling due to stretching and shrinking.

However, a release sheet provided with an extruded laminate layer of a polyolefin resin on the back surface of the release sheet substrate has a curl resistance when applied to a pressure-sensitive adhesive sheet using a plastic film or metal foil as a surface substrate. Good, but poor printability on the back polyolefin resin layer surface. Further, a release sheet provided with a moisture-proof coating layer containing a polymer resin such as a vinylidene chloride resin or an acrylic resin as a main component on the back surface of the release sheet substrate, a polymer compound is provided on the back surface of the release sheet substrate. Since the moisture-proof coating agent solution dissolved or dispersed in water or a solvent is directly applied, the release sheet substrate absorbs water and the solvent in the coating process of the moisture-proof coating layer, and the release sheet has wrinkles and Unevenness occurs. Therefore, when this release sheet is applied to a pressure-sensitive adhesive sheet using a plastic film or a metal foil as a surface substrate, there is a problem that the smoothness of the surface substrate is impaired and the commercial value is reduced.

[0007]

In order to solve the above-mentioned problems, use of a plastic film as a base material for a release sheet can be mentioned. In the case of a plastic film, however, the coating property and curing property of a release agent are used. Poor
In addition, there is a problem that the drying property and adhesion of the printing ink are poor. The present invention solves the drawbacks of a release sheet using a plastic film as a release sheet or a release sheet substrate provided with a moisture-proof layer such as a polyolefin resin layer on the back surface of a conventional release sheet substrate, and as a surface substrate. Even when applied to pressure-sensitive adhesive sheets using plastic films or metal foils, the smoothness of the substrate surface is not impaired, and the release sheet has excellent printability on the non-release agent side, and furthermore, the curl of the pressure-sensitive adhesive sheet Is intended to provide a good release sheet.

[0008]

Means for Solving the Problems The present inventors have attempted to solve the above-mentioned problems by using a polyolefin-based synthetic paper as a base material for a release sheet. However, when a silicone-based release agent was applied, only those having insufficient curing of the release agent layer were obtained. Usually, polyolefin-based synthetic paper has a base material having a multilayer structure and is subjected to a stretching treatment. However, as it is, as with a plastic film, the drying properties and adhesion of printing ink are poor. For example, products provided with a resin layer (primer layer) containing a nitrogen compound such as an amine are commercially available. The present inventors have found that the nitrogen compound contained in the resin layer inhibits the curing of the silicone-based release agent and is a serious obstacle to using polyolefin-based synthetic paper as the base material of the release sheet. Was.

That is, the cross-linking reaction of polydimethylsiloxane, which is the main component of the silicone-based release agent, is performed by a chemical reaction between silanol groups and functional groups of the cross-linking agent. Are used as initiators. The platinum catalyst is poisoned by amine, phosphorus, sulfur, and the like in a small amount. Therefore, when there is a component containing amine, phosphorus, sulfur, or the like, curing is inhibited. Therefore, polyolefin-based synthetic paper has a resin layer containing a nitrogen compound on the surface,
A release sheet using this as a base material could not be prepared.

As a result of intensive studies, the present inventors have found that a specific resin is used as an undercoating layer between a substrate and a release agent layer, whereby a resin layer containing a nitrogen compound on the surface of the substrate is used. Even when applied to pressure-sensitive adhesive sheets that use plastic films or metal foils as the surface substrate, there is no inhibition of the curing of the silicone-based release agent, and the curl resistance and surface smoothness of the pressure-sensitive adhesive sheet, and the printability on the non-release agent surface They have found that an excellent release sheet can be obtained, and have completed the present invention.

That is, according to the present invention, an undercoating agent layer containing a (meth) acrylate copolymer is formed on one side of a stretched synthetic paper having a multilayer structure, and a silicone-based layer is formed on the undercoating layer. A release sheet provided with a release agent layer.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION As a substrate used in the present invention,
A stretched synthetic paper having a multilayer structure is used. For example, a thermoplastic resin such as a polypropylene-based resin as a main raw material, a composition obtained by blending an inorganic or organic filler and a small amount of an additive with this is melted, kneaded, and extruded from a slit die of an extruder to form a film. And a film-shaped or tape-shaped synthetic paper by an internal paper-forming method manufactured by further biaxial stretching. The thickness of the synthetic paper is 0.01
About 0.5 mm can be used.
05-0.1 mm can be used. Synthetic paper by the usual internal papermaking method has a three-layer structure of a base layer stretched and oriented in the longitudinal direction and the transverse direction, and a paper-like layer stretched and oriented only in the transverse direction existing above and below the base layer. In the paper-like layer, there are a large number of microvoids generated by blending an inorganic filler with a thermoplastic resin and stretching, and the presence of the microvoids provides white opacity, and printability and writability, and The mechanical strength of the base layer is obtained.

However, since the adhesion and drying properties of various printing inks are insufficient with only the microvoids, a resin layer containing a nitrogen compound is usually applied to the surface of synthetic paper. The resin layer containing the nitrogen compound has a strong coordination force to a platinum catalyst, which is a reaction initiator of the crosslinking reaction, in the crosslinking reaction of polydimethylsiloxane, which is a main component of the silicone-based release agent, and becomes a catalyst poison.

In the present invention, a nitrogen compound inhibits the curing of the silicone-based release agent by forming an undercoat layer containing a (meth) acrylate copolymer as a main component on the surface to which the silicone-based release agent is applied. Without this, a release agent layer can be formed. When an undercoat layer containing a resin other than the (meth) acrylic acid ester copolymer, for example, a shellac resin or the like as a main component is formed, the curing of the silicone-based release agent is inhibited, and the release agent layer is formed. Can not do.

Examples of the (meth) acrylate copolymer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate,
2-hydroxybutyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate,
One or more (meth) acrylic acid esters such as glycerol mono (meth) acrylate, and (meth) acrylic acid, itaconic acid, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate; Examples thereof include those copolymerized with one or several vinyl monomers such as 2-ethylhexyl acrylate.

In particular, as a main component of the copolymer, a copolymer composed of ethyl acrylate and methyl methacrylate can be preferably used in terms of heat resistance, solvent resistance, adhesion to a substrate, and the like. The mixing ratio of ethyl acrylate and methyl methacrylate is preferably 5 to 70 parts by weight, more preferably 10 to 30 parts by weight, based on 100 parts by weight of ethyl acrylate.

The (meth) acrylate copolymer is
For example, a polyvinyl alcohol and a modified product thereof, a neutralized product of a polycarboxylic acid copolymer, or an emulsion obtained by further using an emulsifier in combination can be used as a primer.

Examples of the emulsifier include anionic surfactants such as potassium oleate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate, and polyoxyethylenedialkylammonium sulfate; Nonionic surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyethylene glycol fatty acid ester, and polyoxyethylene sorbitan fatty acid ester can be exemplified. In addition, a melamine resin, an epoxy resin, an isocyanate-based resin, an aziridine-based compound, or the like may be used as a cross-linking agent, if necessary.

As a method of applying the undercoating agent, the undercoating agent can be applied by a usual coating machine, for example, a bar coater, a roll coater, a gravure coater or the like. The coating amount of the primer, 0.5 to 10 g / m ² in dry weight, preferably, suitably 3 to 8 g / m ^2. Incidentally, 0.
If it is less than 5 g / m ² , the effect as an undercoat layer is poor, and if it exceeds 10 g / m ² , the necessity is poor from the viewpoint of economy.

As the release agent applied to the release sheet, for example, a silicone release agent such as a heat cure type silicone release agent or a UV cure type silicone release agent can be used. Incidentally, when a non-silicone release agent is used, it is difficult to control the release force, there is a release sound (zipping) at the time of release sheet release, and the peel feeling is not preferable. As a method of applying the release agent, it can be applied by a usual coating machine, for example, a bar coater, a roll coater, a gravure coater or the like. The coating amount of the release agent is 0.05 to 3 g / m ² in terms of dry weight, preferably 0.2 to 1.
5 g / m ² is appropriate. Incidentally, it is less than 0.05 g / m ² poor effect as a release layer, also exceed 3 g / m ² has poor necessity from the viewpoint of economy.

[0021]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but it is needless to say that the present invention is not limited to these examples.

Example 1 "Formation of undercoat layer" As a base material, a polypropylene synthetic paper having a multilayer structure and stretched (trade name: YUPO (SGS80), manufactured by Oji Oil Chemicals Co., Ltd.) Sa: 8
0 μm) was used. As a primer, a copolymer resin emulsion of ethyl acrylate and methyl methacrylate (trade name: Newcoat PV-
412, manufactured by Shin-Nakamura Chemical Co., Ltd.) was applied by 5 g / m ² by bar coating, and then dried in an oven at 100 ° C. for 1 minute to form an undercoat layer. [Production of Release Sheet] Subsequently, a silicone-based release agent (trade name: BY24-312, manufactured by Toray Dow Corning Silicone Co., Ltd.) was applied on the undercoat layer by bar coating at a rate of 0.2 g / m ² . Thereafter, by drying in an oven at 120 ° C. for 1 minute, a release agent layer was formed to obtain a release sheet.

Example 2 "Formation of undercoat layer" Emulsion resin emulsion of ethyl acrylate and methyl methacrylate (trade name: Newcoat PV-412, manufactured by Shin-Nakamura Chemical Co., Ltd.)
An undercoat layer was formed in the same manner as in Example 1 except that the coating amount was 1 g / m ² . "Production of release sheet" A release agent layer was formed on this undercoat layer in the same manner as in Example 1 to obtain a release sheet.

Example 3 "Formation of Undercoating Layer" Copolymer resin emulsion of ethyl acrylate and methyl methacrylate (trade name: Newcoat PV-412, manufactured by Shin-Nakamura Chemical Co., Ltd.)
An undercoating layer was formed in the same manner as in Example 1 except that the coating amount of was 10 g / m ² . "Production of release sheet" Example 1
A release agent layer was formed in the same manner as described above to obtain a release sheet.

Example 4 "Formation of Undercoating Layer" A copolymer resin emulsion of ethyl acrylate and methyl methacrylate (trade name: Newcoat PV-400, manufactured by Shin-Nakamura Chemical Co., Ltd.) was used as the undercoating agent. In the same manner as in Example 1, an undercoat layer was formed. "Production of release sheet" Example 1
A release agent layer was formed in the same manner as described above to obtain a release sheet.

Example 5 "Formation of undercoat layer" As a base material, a polypropylene-based synthetic paper having a multilayer structure and stretched (trade name: YUPO (FPG80), manufactured by Oji Oil Chemicals, Inc.) Sa: 8
0 μm) was used. As an undercoating agent on the surface of the base material, a copolymer resin emulsion of ethyl acrylate and methyl methacrylate (trade name: Newcoat PV-41)
2, Shin Nakamura Chemical Co., Ltd.)
/ M ^2, and dried in an oven at 100 ° C. for 1 minute to form an undercoat layer. "Production of release sheet" Example 1
A release agent layer was formed in the same manner as described above to obtain a release sheet.

Comparative Example 1 "Production of Release Sheet" The same substrate (trade name: YUPO (SGS80)) as in Example 1 was used, and a pearl surface of the substrate was coated with a silicone-based release agent (Toray Dow Corning Silicone Co., Ltd.). After applying 0.2 g / m ² by bar coating, a release agent layer was formed by drying in an oven at 120 ° C. for 1 minute to obtain a release sheet.

Comparative Example 2 "Production of release sheet" As a substrate, a polyester film (trade name: Lumirror, manufactured by Toray Industries, Inc., thickness: 50 μm)
m) was used. A silicone-based release agent (trade name: BY24-312, manufactured by Toray Dow Corning Silicone Co., Ltd.) was applied to the corona-treated surface of the substrate at 0.2 g / bar by bar coating.
After m ² coating, the resultant was dried in an oven at 120 ° C. for 1 minute to form a release agent layer, thereby obtaining a release sheet.

Comparative Example 3 "Preparation of release sheet" As a base material, high-quality paper (trade name: O
KC-110, manufactured by Oji Paper Co., Ltd., 110 g / m ² )
It was used. A linear low-density polyethylene having a density of 0.928 (trade name: L-1054D, manufactured by Idemitsu Petrochemical Co., Ltd.) was extruded by a laminator to obtain a resin temperature of 32.
At 0 ° C., the base material was laminated on one surface to a thickness of 10 μm and on the other surface to a thickness of 20 μm. Next, the surface of the linear low-density polyethylene layer provided on the one surface is adjusted to have a wetting index of 45 dyn / cm by a method specified in JIS K 6768 by a corona discharge treatment machine (manufactured by Kasuga Electric Co., Ltd.). Then, a silicone-based release agent (manufactured by Toray Dow Corning Silicone Co., Ltd., trade name: BY24-312) was applied by bar coating at a rate of 0.2 g / m ² , and then heated in a 120 ° C. oven for 1 minute. By drying, a release agent layer was formed. Further, a polyvinylidene chloride resin emulsion (manufactured by Toyo Morton Co., Ltd., trade name: SF-2011) is coated on the other surface of the release sheet substrate by bar coating at a rate of 5 g / m ² , and an oven at 110 ° C. To form a moisture-proof layer. Further, a styrene-acrylic copolymer resin emulsion (manufactured by Siden Chemical Co., Ltd., trade name: EK-38) was applied on the moisture-proof layer by bar coating at 5 g / m2.
^Two coatings were performed and dried in an oven at 110 ° C. to form an easily adhesive layer of the printing ink to obtain a release sheet.

Comparative Example 4 As a substrate, the same substrate as in Example 1 (trade name: Yupo (SG)
S80)), after applying a non-silicone release agent (manufactured by Yushi Kogyo Co., Ltd., trade name: Piroyl 1010) to the pearl surface of the base material by bar coating at 0.2 g / m ^2. After drying in an oven at 80 ° C. for 1 minute, a release agent layer was formed to obtain a release sheet.

Comparative Example 5 "Formation of undercoat layer" As a base material, a polypropylene synthetic paper having a multilayer structure and stretched (trade name: YUPO (SGS80), manufactured by Oji Yuka Synthetic Paper Co., Ltd.) Sa: 8
0 μm) was used. As a primer, a shellac resin (trade name: Piroyl 1010, on the other hand, manufactured by Yushi Kogyo Co., Ltd.) was applied as a primer to the pearl surface of the substrate by bar coating at a rate of 0.2 g / m
^{After 2} coatings, the coating was dried in an oven at 100 ° C. for 1 minute to form an undercoat layer. "Production of release sheet" Example 1
A release agent layer was formed in the same manner as described above to obtain a release sheet.

[0032]

[Evaluation] Cure properties and smoothness of the release agent on the release agent layer surface of the release sheet obtained in this way, printability of the non-release agent layer surface, and curl of the pressure-sensitive adhesive sheet obtained using each of these release sheets The peeling feeling of each release sheet from the adhesive surface was evaluated, and the results are shown in [Table 1].

The pressure-sensitive adhesive sheet was manufactured as follows. After applying a solvent-type acrylic pressure-sensitive adhesive (trade name: BPS-4891, manufactured by Toyo Ink Mfg. Co., Ltd.) to the release agent layer surface of the release sheet by a comma coater at 23 g / m ² ,
It was dried in an oven at 110 ° C. for 2 minutes to form an adhesive layer. A surface substrate composed of a polyester film (trade name: Lumirror, manufactured by Toray Industries, Inc.) having a thickness of 50 μm was laminated on the pressure-sensitive adhesive layer, and bonded by a press roll to produce a pressure-sensitive adhesive sheet.

"Cure Property of Release Agent" The cure property of the release agent was evaluated by a finger rubbing method. After the coating film was rubbed with a finger 10 times, clouding (smear) and peeling (rub off) of the coating film were observed. Judgment was made on the basis of the occurrence. (Criterion) ：: smear of coating film, no rub-off Δ: partial smear, no rub-off ×: rub-off of coating film.

"Smoothness" The smoothness of the release agent surface was determined by JAPAN.
TAPPI paper pulp test method
Issue) No. 5 Measured using an Oken-type smoothness and air permeability tester. The measurement results show that the higher the numerical value, the higher the smoothness.

"Printability of non-release agent layer surface"
Using a RI tester (manufactured by Akira Seisakusho Co., Ltd.), print ink (trade name: TK Mark V) on the non-release agent side of each release sheet
After printing 0.6 cc of Ink M, T & K TOKA Co., Ltd.), a cellophane adhesive tape (manufactured by Oji Chemical Co., Ltd.) was adhered to the printed surface, and immediately after peeling off, judgment was made based on the degree of peeling of the ink. . (Criterion) ○: Ink cannot be removed at all △: Ink can be partially removed ×: Ink can be removed almost

[Curl] The curl of the pressure-sensitive adhesive sheet was measured by cutting a test piece into a piece of 200 mm × 200 mm, placing it on a flat plate with the non-release agent side of the release sheet facing up, at 23 ° C., 30% R
After standing for 24 hours in each environment of H, 23 ° C., 65% RH, and 23 ° C., 80% RH, the height of the four corners of the test piece from the flat plate was measured, and the average value was shown as curl. . In the measured values, + (plus) indicates curl when the four corners were lifted with the surface substrate side of the adhesive sheet facing upward, and-(minus) indicates the non-release agent surface of the release sheet facing upward. Shows the curl when the four corners are lifted.

"Feeling of Peeling of Peeling Sheet" The feeling of peeling of the peeling sheet from the pressure-sensitive adhesive sheet was determined according to the following criteria as to whether or not a zipper sound was generated when the peeling sheet was peeled off by a person, and peeling was not possible. . (Criterion) ○: good peeling feeling △: some zipping ×: severe zipping, no peeling

"Comprehensive evaluation" As a comprehensive evaluation, evaluation was performed according to the following criteria. (Criterion) ：: Good practicality ○: Good practicality ×: Poor practicality

[0040]

[Table 1]

[0041]

As described in detail above, according to the present invention, by applying to a pressure-sensitive adhesive sheet using a plastic film or a metal foil as a surface substrate, the curl resistance and surface smoothness of the pressure-sensitive adhesive sheet, and a non-peeling agent A release sheet having excellent printability on the surface can be obtained.

Claims (2)

[Claims] An undercoat layer containing a (meth) acrylate copolymer is formed on one side of a stretched synthetic paper having a multilayer structure, and a silicone release agent layer is formed on the undercoat layer. A release sheet provided. 2. The method according to claim 1, wherein the (meth) acrylate copolymer is
The release sheet according to claim 1, which is a copolymer of ethyl acrylate and methyl methacrylate.