JP2000345125A - Surface protection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a surface protection film enabling unfolding force to be kept small for a long term without previous release processing of the underside of a substrate layer and enabling both a substrate layer and a pressure sensitive adhesive layer to have sufficient adhesive strength for a long term by superimposing a resin layer on the pressure sensitive adhesive layer so as to be integrated. SOLUTION: A resin layer composed of (A) 100 pts.wt. olefin-based resin and (B) 1-10 pts.wt. silicone-based fine particles and a pressure sensitive adhesive layer are laminated directly or indirectly so as to be integrated. The ingredient B preferably is fine particles obtained by copolymerizing an organopolysiloxane expressed by the formula [wherein R is a (substituted) 1-12C hydrocarbon and >=50% of all Rs is methyl group; X is a radically polymerizable functional group-containing organic group and; (n) is 5-200] with a non-crosslinking radically polymerizable comonomer and a crosslinkable radically polymerizable comonomer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a surface protection film.

[0002]

2. Description of the Related Art Conventionally, a surface protective film has been used to prevent dust from adhering or scratching on the surface of an adherend such as a synthetic resin plate, a metal plate, a decorative plywood, a coated plywood, and various nameplates. It has been used temporarily attached to the surface. As the surface protective film, for example, a film in which an adhesive layer is laminated on a base material layer made of an olefin-based resin film is known. And when these surface protection films are used as products,
Usually, it is wound up in a coil shape to form a wound body.

[0003] However, in these rolls, since the base layer and the pressure-sensitive adhesive layer are adhered to each other with relatively strong adhesive force, it is difficult to peel off the surface protective film when rewinding the surface protective film in use. It is. Therefore, the force required to rewind the surface protection film (hereinafter referred to as "development force")
The surface of the base material layer on the side opposite to the pressure-sensitive adhesive layer (hereinafter, referred to as “back surface of the base material layer”) is subjected to a release treatment for the purpose of reducing the amount of resin.

Conventionally, as this release treatment, a method in which a release agent is applied in advance to the back surface of the base material layer is generally used. But,
It is difficult to adhere the release agent firmly to the base material layer and make it easy to properly separate from the pressure-sensitive adhesive layer. Methods such as corona treatment of the back surface of the layer have been proposed.

[0005]

However, the above-mentioned mold release treatment complicates the coating process and further lowers the yield,
There is a problem that leads to cost increase.

On the other hand, in consideration of the working environment, the base material layer and the pressure-sensitive adhesive layer must be separated from each other in order to maintain the adhesion between the base material layer and the pressure-sensitive adhesive layer and to eliminate the solvent of the pressure-sensitive adhesive layer. A method of forming by coextrusion and laminating at the same time has also been proposed (JP-A-61-103975, column of prior art).

[0007] However, even in the coextrusion method, some release treatment is required on the back surface of the base material layer, but the release treatment cannot be performed in advance, and there is a restriction on the timing of the treatment. Therefore,
A method of friction-treating the back surface of a base material layer of a laminate obtained by a co-extrusion method with a roll, cloth, or the like has also been proposed (Japanese Patent Application Laid-Open No. 2-252777). However, the effect of the friction treatment may vary depending on the composition of the base material layer, and in some cases, the developing force cannot be satisfactorily reduced.

The present invention solves the above-mentioned problems, and can reduce the developing force for a long period of time without subjecting the back surface of the base material layer to a mold release treatment in advance, and make the base material layer and the pressure-sensitive adhesive layer sufficiently long-term. It is an object of the present invention to provide a surface protective film having a high adhesive strength.

[0009]

The surface protective film of the present invention comprises a resin layer comprising 100 parts by weight of an olefin resin and 1 to 10 parts by weight of silicone fine particles, and a pressure-sensitive adhesive layer which is directly or indirectly laminated and integrated. Is what is being done.

In the present invention, the resin layer comprises 100 parts by weight of an olefin resin and 1 to 10 parts by weight of silicone fine particles. When the base layer is a single layer, the entire base layer is formed. In some cases, it refers to a layer constituting the back surface of the base material layer.

[0011] The olefin resin is not particularly limited. For example, low density polyethylene,
Medium density polyethylene, high density polyethylene, linear low density polyethylene, ethylene-α-olefin copolymer,
Polypropylene, propylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl (meth) acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-n-butyl acrylate copolymer, and the like. It is preferably used. These olefin resins may be used alone or in combination of two or more.

The silicone-based fine particles may be a silicone resin, a silicone rubber or the like, preferably a silicone acrylic copolymer, and more preferably,
The following general formula (I)

Embedded image (Wherein R is the same or different from each other and has 1 to 12 carbon atoms)
Represents a substituted or unsubstituted monovalent hydrocarbon group;
0% or more is a methyl group. X represents a radical polymerizable functional group-containing organic group, and n represents an integer of 5 to 200. The spherical fine particles obtained by copolymerizing the organopolysiloxane represented by the formula (1) with a non-crosslinkable radical polymerizable monomer copolymerizable therewith and a crosslinkable radical polymerizable monomer.

The groups R in the general formula (I) are the same or different and are a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms. Examples of such R include an alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group and an n-hexyl group; an aryl group such as a phenyl group, a tolyl group and a naphthyl group; And alkenyl groups such as allyl group; aralkyl groups such as phenethyl group and benzyl group; and substituted alkyl groups such as 3-chloropropyl group and 3,3,3-trifluoropropyl group. Of these, a methyl group, a butyl group, and a phenyl group are particularly preferable, and in order to impart sufficient sliding properties and blocking resistance, it is preferable that 50% or more of all Rs are methyl groups.

In the formula, when n is too small, the expandability decreases,
If it is too large, the obtained film strength will be reduced.
Preferred is an integer of ~ 200. Here, n represents the degree of polymerization for each individual molecule, and it is preferable that substantially all of n fall within the above range.

The organic group X in the organopolysiloxane represented by the general formula (I) represents a radical polymerizable functional group-containing organic group.

Embedded image (Wherein, R ¹ represents a divalent organic group having 3 to 20 carbon atoms, and R ² represents a hydrogen atom or a methyl group, respectively).

In the above general formula (II), -R ^1-
_{The, - (CH 2) 3 -} , - CH 2 CH (CH 3) CH
_{2 -, - (CH 2)} 4 -, - (CH 2) 6 -, - (CH 2) 3 O (CH
₂ ) ₂ -,-(CH ₂ ) _3- (C ₂ H ₄ O) _2- and the like.

The non-crosslinkable radical polymerizable monomer copolymerizable with the organopolysiloxane represented by the above general formula (I) includes, for example, methyl (meth) acrylate,
Ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate,
Alkyl (meth) acrylates such as isobutyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, and stearyl (meth) acrylate; methoxyethyl (meth) acrylate, butoxyethyl (meth) Alkoxyalkyl (meth) acrylates such as acrylate; cyclohexyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate and the like. These (meth) acrylates may be used alone or in combination of two or more.

Further, a radical polymerizable monomer other than the above may be used in combination with the above (meth) acrylates as long as the effects of the present invention are not impaired. Such monomers include, for example, maleic acid, fumaric acid,
Unsaturated acids such as (meth) acrylic acid; (meth) acrylamides such as N-methylol (meth) acrylamide; 3-trimethoxysilylpropyl (meth) acrylate, 3-triethoxysilylpropyl (meth) acrylate, 3- Dimethoxymethylsilylpropyl (meth)
Radical polymerizable silane compounds such as acrylate, vinyltriethoxysilane, 4-vinylphenyltrimethoxysilane, and vinylmethyldimethoxysilane; styrene, acrylonitrile, vinylpyridine, vinylpyrrolidone,
Examples include vinyl alkyl ethers, radically polymerizable macromonomers of polyoxyalkylenes having one radically polymerizable group in the molecule, and polycaprolactone.

Examples of the crosslinkable radical polymerizable monomer copolymerizable with the organopolysiloxane represented by the general formula (I) include, for example, ethylene glycol di (meth)
Acrylate, diethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di (meth) acrylate, allyl (meth)
Radical polymerizable monomers having two or more ethylenically unsaturated groups in one molecule such as acrylate, propylene glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, and divinylbenzene are exemplified.

The average particle size of the above-mentioned spherical fine particles is preferably 5 to 30 μm, more preferably 10 to 20 μm. It is.

On the other hand, for imparting effects such as good slipperiness and high transparency, a true spherical one is excellent. In this case, f = [M / (π / 4)] ^0.5 / Nmax [where M is the cross-sectional area (mm ² ) when cut at an arbitrary angle including the center of the fine particle, and Nmax is the longest diameter of the cross-section. (Mm). ] Is preferably 0.8 or more, more preferably 0.85 or more.

Examples of the silicone-based fine particles include, for example, "Charine R17" manufactured by Nissin Chemical Industry Co., Ltd.
0 "," Charine R210 "and the like.

When the amount of the silicone-based fine particles is too small, the effect of reducing the developing power is reduced, and when the amount is too large, the bleed-out occurs and is transferred to the surface of the pressure-sensitive adhesive, which adversely affects the physical properties of the pressure-sensitive adhesive and increases the material cost. So, olefin resin 1
The amount is limited to 1 to 10 parts by weight, preferably 3 to 8 parts by weight, per 00 parts by weight.

In the resin layer, an antioxidant, a weather stabilizer,
An ultraviolet absorber, a pigment, and the like may be added.

In the present invention, the thickness of the resin layer is appropriately selected depending on the application, but is preferably 5 to 2 in terms of moldability and ease of use.
00 μm is preferred, and 30 to 20 when the base material layer is a single layer.
0 μm, and more preferably 5 to 50 μm for a multilayer structure.

In the present invention, the pressure-sensitive adhesive layer is directly or indirectly laminated and integrated with the resin layer.
The pressure-sensitive adhesive used for the pressure-sensitive adhesive layer is not particularly limited, but is bonded to an adherend, and can be easily separated from the adherend after use, for example, an ethylene-vinyl acetate copolymer, a low-density copolymer. Polyethylene, linear low-density polyethylene, ethylene-ethyl acrylate copolymer, ethylene-methyl (meth) acrylate copolymer, ethylene-α
-Olefin copolymers, (hydrogenated) styrene-diene copolymers, polyisobutylene, polybutene, (hydrogenated) polyisoprene, and the like. These may be used alone or in combination of two or more.

If necessary, the pressure-sensitive adhesive layer may be, for example,
An antioxidant, a weather resistance stabilizer, an ultraviolet absorber, a tackifier and the like may be added.

Although the thickness of the pressure-sensitive adhesive layer is not particularly limited, it is preferably 5 to 50 μm in terms of pressure-sensitive adhesive performance and cost.

The method for producing the surface protective film of the present invention is not particularly limited. For example, a substrate layer containing the above resin layer is prepared by extrusion molding, and one surface thereof is coated with a solution of the above adhesive. After drying after the work, it may be wound and cured in a coil shape, and the components of the base layer and the adhesive,
After being subjected to collective molding by a co-extrusion method using an inflation method or a T-die method, it may be wound into a coil shape.

Among them, the surface protective film obtained by the co-extrusion method is excellent in anchoring property between the base layer and the pressure-sensitive adhesive layer. This is preferable in that a problem of remaining surface is unlikely to occur, and a surface protection film can be manufactured at low cost because the number of steps is smaller than that of a method of applying a solution of an adhesive after forming only the base material layer.

[0031]

The present invention will be described below in more detail with reference to examples.

Examples 1 to 3 and Comparative Examples 1 and 2 An organopolysiloxane represented by the following chemical formula was added to a mixture of 90 parts by weight of methyl methacrylate and 5 parts by weight of butanediol diacrylate.

Embedded image Was added, and these were copolymerized by emulsion polymerization. The obtained copolymer was dried by a spray-drying method and pulverized by a jet mill to obtain silicone-based fine particles. The average particle size of the obtained silicone-based fine particles is 3 μm,
The sphericity was 0.91.

Next, a predetermined amount of low-density polyethylene (trade name "Mirason 12", manufactured by Mitsui Chemicals, Inc.)
(MFR at 90 ° C .: 3.0 g / 10 min) and the silicone-based fine particles were melt-mixed to obtain a uniform mixture for a base material layer.

On the other hand, a hydrogenated styrene-butadiene copolymer (trade name “Clayton G1726” manufactured by Shell Chemical Co., Ltd., styrene content 30% by weight,
A composition consisting of 1 part by weight of an antioxidant (manufactured by Ciba Specialty Chemicals, trade name "Irganox 1010") with respect to 100 parts by weight of MFR at 90 ° C .: 23 g / 10 min was subjected to the following production. .

The above mixture for a base material layer and the pressure-sensitive adhesive composition were co-extruded by an inflation method to obtain a laminated film comprising two layers of a base material layer of 40 μm and a pressure-sensitive adhesive layer of 20 μm. The obtained laminated film was used as a roll, cured at the temperature shown in Table 1 for 100 hours to obtain a roll of the surface protective film, and subjected to the following evaluation.

Evaluation Rolling Force of Surface Protective Film The roll of the obtained surface protective film was rewound at 30 m / min, and the force required at that time was measured. In Table 1, 5
It was shown as a converted value of 0 mm width. Adhesive strength The unwound surface protection film is adhered to a stainless steel plate (SUS304, 280 polishing) at a speed of 300 mm / min using a 2 kg pressure roller under an environment of 23 ° C. and 65% RH, and left for 30 minutes. JIS Z023
The 180 ° peel adhesion at a width of 25 mm was measured according to 7. The above results are summarized in Table 1.

[0037]

[Table 1]

[0038]

According to the surface protective film of the present invention, a resin layer comprising an olefin resin and a specific amount of silicone fine particles and a pressure-sensitive adhesive layer are directly or indirectly laminated and integrated, so that the developing power is small. Nevertheless, the adhesive properties are not impaired. Also, compared to conventional methods such as friction treatment,
The deployment force can be easily reduced without varying the effect.

In the present invention, the silicone-based fine particles are obtained by copolymerizing an organopolysiloxane having a specific structure with a non-crosslinkable radical polymerizable monomer copolymerizable therewith and a crosslinkable radical polymerizable monomer. When the spherical fine particles are obtained by the above method, the developing force can be further reduced.

Claims (3)

[Claims] 1. A surface protective film comprising a resin layer composed of 100 parts by weight of an olefin-based resin and 1 to 10 parts by weight of silicone-based particles, and a pressure-sensitive adhesive layer which are directly or indirectly laminated and integrated. 2. The method according to claim 1, wherein the silicone-based fine particles are of the following general formula (I): (Wherein R is the same or different from each other and has 1 to 12 carbon atoms)
Represents a substituted or unsubstituted monovalent hydrocarbon group;
0% or more is a methyl group. X represents a radical polymerizable functional group-containing organic group, and n represents an integer of 5 to 200. ), And spherical fine particles obtained by copolymerizing an organopolysiloxane represented by the formula (I) with a non-crosslinkable radical polymerizable monomer copolymerizable therewith and a crosslinkable radical polymerizable monomer. The surface protective film according to claim 1. The organic group X in the organopolysiloxane represented by the general formula (I) is represented by the following general formula (II): 3. The surface protective film according to claim 1, wherein R ¹ represents a divalent organic group having 3 to 20 carbon atoms, and R ² represents a hydrogen atom or a methyl group. .