JP2003041216A - Surface protecting sheet and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface protecting sheet, with both a base layer and a pressure-sensitive adhesive layer fabricated by coextrusion and with the base layer treated to be releasable, easy to be unwound from a wound unit or the like and free of released component transfer onto the adhesive layer and therefore leaving no stain. SOLUTION: The surface protection sheet is manufactured by the method wherein, following the fabrication of a film by coextrusion of a base layer containing a polyolefinic resin and a pressure-sensitive adhesive layer containing a thermoplastic elastomer, a releasable layer is successively fabricated of a release agent on the surface opposite to the pressure-sensitive adhesive layer- covered surface of the base layer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a surface protective sheet and a method for producing the same. The surface protection sheet of the present invention is, for example, a metal plate, a painted metal plate, an aluminum sash, a resin plate, a decorative steel plate, a vinyl chloride laminated steel plate, a glass plate, etc., when carrying, processing or curing the members, etc. Used for applications such as sticking and protecting the surface.

[0002]

2. Description of the Related Art Conventionally, from the viewpoint of productivity and cost, a surface protective sheet is produced by forming a base material layer and an adhesive layer by a coextrusion method. Further, since the surface protection sheet is used as a wound body or the like, the back surface of the base material layer (the surface opposite to the adhesive layer) is required to have a releasability capable of light peeling in order to easily perform rewinding and the like. . As a general surface protective sheet, for example, one using a polyolefin resin such as polyethylene for the base material layer and an ethylene / vinyl acetate copolymer for the adhesive layer is known. With such a type of surface protection sheet, rewinding is possible without subjecting the back surface of the base material layer to a release treatment.

In recent years, a strong adhesive type surface protective sheet using a styrene elastomer as an adhesive layer has been commercialized. In such a type of surface protection sheet, a mold release treatment is required on the back surface of the base material layer in order to easily perform rewinding and the like. However, it was not practical in terms of manufacturing equipment to apply a release agent to the back surface of the base material layer of the surface protection sheet produced by the coextrusion method to perform the release treatment.

As a method for releasing the back surface of the base material layer of the surface protective sheet produced by the coextrusion method, for example, in JP-A-2-252777, the back surface of the base material layer is
A method of rubbing with a roll or cloth has been proposed. However, the release treatment method has a problem that it is difficult to uniformly perform the friction treatment, good release properties cannot be obtained, and the rewinding force cannot be sufficiently reduced. Further, the releasing effect may vary depending on the composition of the base material layer. In particular, variations in the friction treatment effect tended to become more remarkable as the production speed increased. This is because it is necessary to increase the relative speed of the friction processing rolls due to the increase in the production speed, and it is considered that the friction processing cannot be stably performed because of this. Further, the friction treatment method is effective only for the polyethylene resin among the olefin resins used as the material for forming the base material layer, and hardly effective for the polypropylene resin. Therefore, in a surface protection sheet using a polypropylene-based substrate, good releasability cannot be obtained, and unwinding failure may occur.

Further, JP-A-57-139163 proposes a releasing treatment method in which a fatty acid amide is added to a base material layer or an adhesive layer. However, the releasing treatment method has a problem that the fatty acid amide causes transfer onto the surface of the pressure-sensitive adhesive layer, which in turn transfers to the adherend, causing contamination and lowering the adhesive strength. In the above-mentioned mold release treatment method, a long-chain alkyl polymer, which has less contamination, is added to the base material layer in the same manner as the mold release agent instead of the fatty acid amide, and the effect is confirmed. However, it was not possible to improve the pollution property.

[0006]

DISCLOSURE OF THE INVENTION The present invention is a surface protection sheet in which a base material layer and an adhesive layer are formed by a coextrusion method, and the base material layer is subjected to a release treatment, such as a wound body. An object of the present invention is to provide a surface protective sheet which has good rewinding property from the sheet, does not transfer the release component to the adhesive layer, and has no problem of contamination.

[0007]

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found the following surface protective sheet and a method for producing the same, and have completed the present invention.

That is, the present invention is a surface protective sheet in which a base material layer containing a polyolefin resin and an adhesive layer containing a thermoplastic elastomer are formed by coextrusion, and the adhesive layer of the base material layer is provided. A surface protective sheet having a release layer formed of a release agent on the surface opposite to the surface.

In the surface protection sheet, the release layer preferably has a thickness of 1 to 1000 nm.

Further, according to the present invention, after a base material layer containing a polyolefin resin and a pressure-sensitive adhesive layer containing a thermoplastic elastomer are formed by co-extrusion, the surface of the base material layer opposite to the pressure-sensitive adhesive layer-attached surface is continuously formed. The present invention relates to the method for producing a surface protection sheet, wherein a release layer is formed on the surface with a release agent.

In the present invention, the release layer is formed on the base material layer by continuously providing the surface protective sheet having the base material layer and the adhesive layer formed by the coextrusion method with a release agent. It is possible to attach. The release layer can obtain good rewinding property regardless of the type or composition of the polyolefin forming the base material layer. Further, the release layer has no transferability of the release component to the adhesive layer and thus has no problem of contamination. In particular, when the release layer is formed to have a thin film thickness of 1 to 1000 nm, the effect of reducing contamination is great. The reason for this is not clear, but it is considered that transfer of the release layer to a pressure-sensitive adhesive layer is reduced due to its film strength.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of the surface protective sheet,
A base material layer 1 containing a polyolefin-based resin and a pressure-sensitive adhesive layer 2 containing a thermoplastic elastomer are formed by a co-extrusion method, and the base material layer 1 is separated from the surface opposite to the attachment surface of the pressure-sensitive adhesive layer 2. A release layer 3 made of a mold agent is formed.

The polyolefin resin forming the base material layer 1 is not particularly limited, and may be, for example, polypropylene or a block resin composed of a propylene component and an ethylene component.
Random propylene-based polymers; low-density, high-density, linear low-density polyethylene and other ethylene-based polymers; ethylene-α olefin copolymers and other olefin polymers, ethylene-vinyl acetate copolymers, ethylene-methyl methacrylate Examples thereof include an olefin polymer of an ethylene component such as a copolymer and another monomer. These polyolefin resins may be used alone or in combination of two or more.

The base material layer 1 contains an olefin resin as a main component, but for the purpose of preventing deterioration, for example, a light stabilizer such as an antioxidant, an ultraviolet absorber, a hindered amine light stabilizer, and an antistatic agent. In addition to the agent, for example, fillers such as calcium oxide, magnesium oxide, silica, zinc oxide and titanium oxide, additives such as pigments, anti-corrosion agents, lubricants, anti-blocking agents and the like can be appropriately blended.

The thickness of the base material layer 1 is not particularly limited,
It is usually about 20 to 300 μm, preferably 30 to 2
The thickness is 50 μm, more preferably 40 to 200 μm. Further, the base material layer 1 may be a single layer or a multilayer including two or more layers.

On the surface of the base material layer 1 on which the release layer 3 is attached,
For example, corona discharge treatment, flame treatment, plasma treatment,
If necessary, a surface treatment such as a putter etching treatment or an undercoating treatment of a primer or the like for the purpose of improving the adhesion between the release layer 3 and the base material layer 1 can be performed.

As the thermoplastic elastomer forming the adhesive layer 2, those used as the base polymer of the adhesive such as styrene elastomer, urethane elastomer, ester elastomer and olefin elastomer can be used without particular limitation. More specifically,
Styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), styrene-ethylene-butylene copolymer-styrene (SEBS), styrene-ethylene-propylene copolymer-styrene (SEP)
S) and other ABA type block polymers; styrene / butadiene (SB), styrene / isoprene (SI), styrene / ethylene / butylene copolymer (SEB), styrene / ethylene / propylene copolymer (SEP) A, etc.
-B type block polymer; styrene-based random copolymer such as styrene-butadiene rubber (SBR); styrene-ethylene-butylene copolymer-olefin crystal (SE
ABC type styrene / olefin crystal block polymer such as BC; olefin crystal / ethylene-butylene copolymer / olefin crystal (CEBC) or the like
C type olefin crystal block polymer; ethylene-
α-olefin, ethylene-propylene-α-olefin,
Examples thereof include olefin-based elastomers such as propylene-α olefin, and hydrogenated products thereof. These thermoplastic elastomers may be used alone or in combination of two or more.

When the adhesive layer 2 is formed, if necessary, for example, a softening agent, an olefin resin, a silicone polymer, a liquid acrylic copolymer is added to the thermoplastic elastomer for the purpose of controlling the adhesive property. , Phosphate compounds, tackifiers, anti-aging agents, hindered amine light stabilizers, UV absorbers, and other fillers and pigments such as calcium oxide, magnesium oxide, silica, zinc oxide, titanium oxide, etc. The additive can be blended appropriately.

The addition of a tackifier among the above additives is effective for improving the adhesive strength of the adhesive layer 2. Examples of the tackifier include petroleum-based resins such as aliphatic copolymers, aromatic copolymers, aliphatic / aromatic copolymers and alicyclic copolymers, and coumarone-indene resins. , Terpenic resin, terpene phenolic resin, rosin resin such as polymerized rosin, (alkyl) phenolic resin, xylene resin or hydrogenated products thereof, etc., commonly used for adhesives Any thing can be used without particular limitation. These tackifiers may be used alone or in combination of two or more. Hydrogenated tackifiers are preferred from the viewpoints of releasability from the release layer 3 and weather resistance. The tackifier may be a commercially available blend as a blend with an olefin resin.

When a tackifier is used, the amount of the tackifier is not particularly limited, but from the viewpoint of improving the adhesive strength while avoiding the problem of adhesive residue due to a decrease in cohesive strength, it is based on 100 parts by weight of the thermoplastic elastomer. Therefore, it is preferably 80 parts by weight or less, more preferably 60 parts by weight or less, and particularly preferably 50 parts by weight or less.

When a softening agent is added as the above-mentioned additive, it is generally effective in improving the adhesive strength. Examples of the softening agent include low molecular weight diene-based polymers, polyisobutylene, hydrogenated polyisoprene, hydrogenated polybutadiene and their derivatives. Examples of the derivative include those having an OH group or a COOH group at one end or both ends, and specific examples include hydrogenated polybutadiene diol, hydrogenated polybutadiene monool, hydrogenated polyisoprene diol, and hydrogenated polyisoprene. Examples include monoalls. In particular, for the purpose of suppressing the improvement of the adhesiveness to the adherend, hydrogenated products of diene-based polymers such as hydrogenated polybutadiene and hydrogenated polyisoprene, olefin-based softening agents and the like are preferable. Specifically, the trade name "Kurapren LIR-200" manufactured by Kuraray Co., Ltd. and the like are available. These softening agents may be used alone or in combination of two or more.

The molecular weight of the softening agent is not particularly limited and can be set appropriately. However, if the molecular weight becomes small, it may cause substance transfer from the adhesive layer 2 to the adherend or cause heavy delamination. On the other hand, when the molecular weight becomes large, the effect of improving the adhesive strength tends to be poor, so that the number average molecular weight of the softening agent is preferably about 5,000 to 100,000, particularly preferably 10,000 to 50,000.

When a softening agent is used, its blending amount is not particularly limited, but when the blending amount is large, the adhesive residue tends to increase at high temperature or when exposed to the outdoors. It is preferably 40 parts by weight or less, more preferably 20 parts by weight or less, and particularly preferably 10 parts by weight or less with respect to 100 parts by weight of the pressure-sensitive adhesive composition.

The thickness of the adhesive layer 2 is not particularly limited and may be appropriately determined depending on the required adhesive strength and the like.
Usually about 1 to 50 μm, preferably 2 to 40 μm
m, and more preferably 5 to 20 μm.

The surface of the adhesive layer 2 is subjected to a surface treatment such as corona discharge treatment, ultraviolet irradiation treatment, flame treatment, plasma treatment or sputter etching treatment for the purpose of controlling adhesiveness and workability of sticking. Can be applied as needed. Further, the adhesive layer 2 may be protected by temporarily attaching a separator or the like to the adhesive layer 2 until it is put into practical use, if necessary.

As the release agent for forming the release layer 3, a release agent which can impart releasability can be used without particular limitation. For example, the release agent may be a silicone-based polymer or a long-chain alkyl-based polymer. The release agent is
It may be a solventless type, a solvent type dissolved in an organic solvent, or an emulsified type emulsified in water, but a solvent type or an emulsifying type release agent can stably form the release layer 3 on the base material layer 1. It can be attached. In addition, examples of the release agent include ultraviolet curable ones. Specific examples of the releasing agent include Pyroil (manufactured by Yatsusha Yushi Co., Ltd.) and Shin-Etsu Silicone (manufactured by Shin-Etsu Chemical Co., Ltd.).

The thickness of the release layer 3 is not particularly limited, but as described above, it is usually about 1 to 1000 nm, more preferably 5 to 500 nm, especially 10 because the effect of reducing contamination is large when formed into a thin film. It is preferably ˜100 nm.

The surface protective sheet of the present invention comprises the base material layer 1
And a pressure-sensitive adhesive layer 2 are formed by a co-extrusion method, and then a release layer 3 is continuously formed on the surface of the base material layer 1 opposite to the surface where the pressure-sensitive adhesive layer 2 is attached by a release agent. . The line speed of the film forming step and the release treatment step is usually 10 to 1
It is about 00 m / min.

Specifically, for example, as shown in FIG. 2, an extruder 11 is charged with a base material layer 1 forming material, and an extruder 12 is charged with an adhesive layer forming material, and the mixture is extruded and then extruded. The base material layer 1 and the adhesive layer 2 are formed into a film by the coextrusion method using the extruder 13. The coextrusion method can be carried out according to the inflation method, T-die method or the like generally used for film production. The base material layer 1 and the adhesive layer 2 are coextruded in two layers or in multiple layers. The surface treatment can be applied to the base material layer 1 and the adhesive layer 2 if necessary.

In the release treatment step 13 continuously provided on the same line subsequent to the film formation, a release agent 3'releases the base layer 1 on the side opposite to the side where the adhesive layer 2 is attached. Form layer 3. In the mold release treatment step 13 of FIG. 2, the mold release agent 3'is applied by a coating method using a roll coater such as a gravure roll. As the mold release treatment step 13, other known coating methods such as a spraying method using a spray can be used. After the releasing treatment step 13, a drying (curing) step 14 such as heating, ultraviolet ray irradiation, and EB irradiation is performed according to the type of the releasing agent, and then the surface is taken up by a winding roller 15 and The protective sheet is obtained as a wound body.

[0032]

EXAMPLES The present invention will be described below with reference to examples and comparative examples.

Example 1 (Film forming step) A base material layer was formed by adding 4 parts by weight of a white pigment (Dainichi Seika Co., Ltd., HCM2035W) to 100 parts by weight of low-density polyethylene (Tosoh Corp., Petrosene 180). Material and 100 parts by weight of styrene / ethylene butylene / styrene polymer (Asahi Kasei Corp., Tuftec H1042) hydrogenated petroleum resin (Arakawa Chemical Co., Alcon P-
The adhesive layer-forming material containing 100 parts by weight of 100) was co-extruded by a T-die method at a die temperature of 230 ° C. to form a substrate layer of 100 μm and an adhesive layer of 10 μm to form a film. The line speed of the film forming process was 45 m / min.

(Release Processing Step) Following the above film forming step, continuously, on the surface of the base material layer opposite to the adhesive layer-attached surface, as a release agent, a 1% by weight solution of Pyroyl 1010S toluene (one side) After coating with a gravure roll so that the release layer has a thickness (after drying) of 50 nm, the release layer was formed by drying, and a surface protective sheet was prepared. The line speed of the mold release step was 45 m / min.

Example 2 In Example 1 (mold release treatment step), a water-dispersed mold release agent K-256 (manufactured by Chukyo Yushi Co., Ltd.) was used as a mold release agent, and the thickness of the mold release layer (after drying) was A surface protective sheet was produced in the same manner as in Example 1 (mold release treatment step) except that the release layer was formed by coating and drying so as to have a thickness of 100 nm.

Example 3 In Example 1 (mold release treatment step), a UV-curable mold release agent XS56-A2982 (manufactured by GE Toshiba Silicone) was used as a mold release agent, and the thickness of the mold release layer (after drying). Is 100
After coating so as to have a thickness of 10 nm, a surface protection sheet was prepared in the same manner as in Example 1 (mold release treatment step) except that the mold release layer was formed by irradiating ultraviolet rays.

Example 4 In Example 1 (film forming step), polypropylene (made by Idemitsu Petrochemical Co., Ltd., IDEM) was used instead of low density polyethylene.
A film was formed in the same manner as in Example 1 (film forming step) except that ITSU PP F-744NP) was used, and a release layer was formed in the same manner as in Example 1 (release processing step). A protective sheet was prepared.

Comparative Example 1 In Example 1 (film forming process), ethylenebisstearylamide (manufactured by Nippon Kasei Co., Ltd.) was further added to the base layer forming material.
A film was formed in the same manner as in Example 1 (film forming step) except that a part was added, and this was used as a surface protection sheet.

Comparative Example 2 Example 1 (film forming step), except that in Example 1 (film forming step), 3 parts of Pyroyl 1010S (manufactured by Yushisha Co., Ltd.) was further added to the base layer forming material. A film was formed in the same manner, and this was used as a surface protection sheet.

Comparative Example 3 Instead of forming a release layer with a release agent in Example 1 (release processing step), a friction treatment was performed to produce a surface protective sheet. The friction treatment was performed at a relative speed of 100 m / min based on the example of JP-A-9-324159.

Comparative Example 4 In Example 1 (film forming step), polypropylene (made by Idemitsu Petrochemical Co., Ltd., IDEM) was used instead of low density polyethylene.
A film is formed in the same manner as in Example 1 (film forming step) except that ITSU PP F-744NP) is used, and in Example 1 (mold releasing treatment step), a release layer is formed with a release agent. Instead, rubbing treatment was performed to produce a surface protection sheet. The friction treatment was performed at a relative speed of 100 m / min based on the example of JP-A-9-324159.

(Evaluation Test) The surface protective sheets obtained in Examples and Comparative Examples were evaluated for rewinding force and stain resistance. The results are shown in Table 1.

(Rewinding force) A rolled roll of the surface protection sheet was pulled by an Instron type tensile tester at a pulling speed of 300.
Rewinding force (N / 20 mm) is performed at mm / min so that the angle between the rewinding sheet and the roll surface is vertical.
Was measured.

(Staining property) The surface protective sheet was put at 50 ° C./95
After being stored for 1 week in an environment of% RH, it was attached to a stainless plate (304BA plate), further stored in an environment of 50 ° C / 95%, and then peeled at room temperature (23 ° C). The presence or absence of contamination on the stainless steel plate after peeling was confirmed.

[0045]

[Table 1] As shown in Table 1, it can be seen that the surface protective sheet of the present invention has a good rewinding property and does not cause contamination.

[Brief description of drawings]

FIG. 1 is a sectional view of a surface protection sheet of the present invention.

FIG. 2 is an example of a conceptual diagram of a method for producing a surface protection sheet of the present invention.

[Explanation of symbols]

1 Base material layer 2 Adhesive layer 3 Release layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yuki Kobayashi             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. F term (reference) 4F100 AK02B AK02H AK03A AK04B                       AK04H AK06A AK09B AK09H                       AK12B AK12H AK52C AL02B                       AL02H AL05B AL06B AL06H                       AL09B AR00C BA03 BA07                       BA10B BA10C BA15 CA13B                       CC00C EH201 EH462 EJ862                       GB15 GB90 JA20C JB16B                       JL02 JL05 JL06 JL13B                       JL14C YY00C                 4J004 AA02 AA05 AA06 AA07 CA03                       CA04 DA04 DA05 DB01 EA01                       FA04 GA01                 4J040 CA081 DA001 DB021 DM011                       ED001 JA09 JB01 JB09                       NA13 NA17 PA23 PA42

Claims (3)

[Claims] 1. A surface protective sheet in which a base material layer containing a polyolefin resin and a pressure-sensitive adhesive layer containing a thermoplastic elastomer are formed by coextrusion, and the surface of the base material layer on which the pressure-sensitive adhesive layer is provided. A surface protective sheet having a release layer formed of a release agent on the opposite surface. 2. The surface protective sheet according to claim 1, wherein the release layer has a thickness of 1 to 1000 nm. 3. A base material layer containing a polyolefin resin and a pressure-sensitive adhesive layer containing a thermoplastic elastomer are formed by co-extrusion, and then continuously on the surface of the base material layer opposite to the pressure-sensitive adhesive layer-attached surface. The method for producing a surface protective sheet according to claim 1, wherein the release layer is formed with a release agent.