JP2002167567A - Surface-protecting film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a surface-protecting film excellent in flexibility, exhibiting excellent adhesive properties and self-adhesive properties to an adherend over a long period of time and having excellent high-speed peelability. SOLUTION: The surface-protecting film comprises a substrate layer composed of a thermoplastic resin and, laminated thereon, a self-adhesive layer composed of a self-adhesive, where the self-adhesive is a hydrogenated block copolymer represented by the general formulae: A-B-A-B or B-A-B-A-B or (B-A-B)n-X (wherein A is a polymer block mainly composed of a vinyl aromatic compound monomer; B is a polymer block mainly composed of a hydrogenated butadiene monomer having an average 1,2-bond content of 62-99 mole %; (n) is an integer of at least two; and X is a residue of a coupling agent) and having an MFR under a condition of 230 deg.C and a load of 21.2 N of 1.0-20 g/10 min. Preferably, the self-adhesive contains at most 100 pts.wt., based on 100 pts.wt. of the hydrogenated block copolymer, of a tackifier resin. The self-adhesive preferably contains at most 10 pts. wt., based on 100 pts.wt. of the hydrogenated block copolymer, of an adhesion promotion-inhibiting agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface protective film, and more particularly, to a temporary protective film on a surface of an adherend such as a synthetic resin plate, a metal plate, a decorative plywood, a coated coated steel plate, a coated coated resin plate, and various nameplates. The present invention relates to a surface protective film used to prevent dust from adhering to or scratching these surfaces.

[0002]

2. Description of the Related Art During the processing and transport of synthetic resin plates, metal plates, decorative plywood, coated coated steel plates, coated coated resin plates, various nameplates, etc., the surface of these plates may be stained or scratched. In order to prevent this, a surface protective film is frequently used.

The surface protective film usually has a structure in which an adhesive layer is formed on one surface of a base material layer made of a thermoplastic resin, paper, or the like. At the time of use, the surface protective film is temporarily attached to the surface of the adherend such as a synthetic resin plate by the adhesive layer, and functions to protect the adherend surface and prevent adhesion of dirt and scratches. . When the adherend is used, the surface protection film is peeled off from the surface of the adherend. Therefore, the surface protective film needs to have an appropriate degree of tackiness that can be easily temporarily attached to the surface of the adherend, and must have good releasability that can be easily peeled off from the surface of the adherend after use. ,And,
It is required not to contaminate the adherend surface after peeling.

For satisfying the above requirements, for example, Japanese Patent Application Laid-Open No. 5-194923 discloses a general formula A-
The block copolymer represented by BA or AB (A
Represents a styrene-based polymer block, and B represents a butadiene polymer block, an isoprene polymer block, or a polymer block obtained by hydrogenating these. ) And a surface protective film using the pressure-sensitive adhesive composition.

[0005]

However, according to the study of the present inventors, in the surface protection film using the pressure-sensitive adhesive composition described in the above publication, a metal plate (stainless steel plate, aluminum plate, or the like) or a coated coated steel plate ( When sticking to acrylic coated steel sheets, fluorine coated steel sheets, polyester coated steel sheets, etc.), the adhesion is good in an environment with a high ambient temperature, but in an environment with a low ambient temperature, before hydrogenation in the above block copolymer The 1,2-bond amount of the B block is 6
If it is less than 2 mol%, the flexibility may be insufficient.
In addition, even when isoprene is used, in an environment where the ambient temperature is low as described above, sufficient flexibility is not always obtained, the adhesion is reduced, and there is a case where the substrate rises from the adherend.

As described above, when the pressure-sensitive adhesive resin composition has insufficient flexibility, and when the surface roughness of the adherend is large, for example, the center line surface roughness (hereinafter referred to as Ra) However, there is also a problem that it is difficult to exhibit sufficient adhesiveness to an adherend having a rough surface of 1 μm or more. Further, in the pressure-sensitive adhesive resin composition, when the block copolymer has a diblock structure of AB, the cohesive force is easily reduced, and the high-speed peeling property is sometimes deteriorated.

The present invention solves the above problems, and provides a surface protective film having excellent flexibility, good adhesion and adhesion to an adherend, and excellent high-speed peelability. The purpose is to do.

[0008]

The surface protective film according to claim 1 is a surface protective film in which a base layer made of a thermoplastic resin and an adhesive layer made of an adhesive are laminated. Is a resin represented by the general formula ABA-
B or BABAB or (B-A-
B) nX, wherein A is a polymer block mainly composed of a vinyl aromatic hydrocarbon compound monomer, B is a polymer block mainly composed of a hydrogenated butadiene monomer, The average of the amount of 1,2-bonds before hydrogenation is 62 to 99 mol%, n is an integer of 2 or more, and X represents a residue of a coupling agent). It is characterized by being mainly composed of a hydrogenated block copolymer having an MFR of 1.0 to 20 g / 10 minutes under the conditions.

The surface protective film according to claim 2 is the surface protective film according to claim 1, wherein the pressure-sensitive adhesive comprises 100 parts by weight or less of a tackifier resin per 100 parts by weight of the hydrogenated block copolymer. It is characterized by comprising.
The surface protective film according to claim 3 is the surface protective film according to claim 1 or 2, wherein the pressure-sensitive adhesive contains 10 parts by weight or less of an adhesion promotion inhibitor with respect to 100 parts by weight of the hydrogenated block copolymer. It is characterized by comprising.

Hereinafter, the present invention will be described in more detail. The hydrogenated block copolymer in the present invention is a polymer block A mainly composed of a vinyl aromatic hydrocarbon compound monomer.
And a polymer block B mainly composed of a hydrogenated butadiene monomer.

The vinyl aromatic hydrocarbon compound monomer includes, for example, alkyl styrene such as styrene, α-methyl styrene, p-methyl styrene, p-tert-butyl styrene, paramethoxy styrene, vinyl naphthalene and the like. One or two or more are selected, and among them, styrene is preferable.

The content of the vinyl aromatic hydrocarbon compound monomer in the above block copolymer is preferably from 10 to 25% by weight, more preferably from 12 to 25% by weight. If the content is too small, the cohesive strength as an adhesive is reduced, so that adhesive remains on the adherend at the time of re-peeling. If the content is too large, the adhesive strength becomes insufficient and it becomes difficult to adhere to the adherend. The content of the vinyl aromatic hydrocarbon compound monomer can be measured by a magnetic resonance apparatus (NMR), an ultraviolet spectrophotometer (UV), or the like.

In the present invention, the term "mainly composed of" means, for example, "mainly composed of a vinyl aromatic hydrocarbon compound monomer" when one or more of the vinyl aromatic hydrocarbon compound monomers are used. Or the other monomer which forms a living anion polymer with them, for example, is 5
The case where it is copolymerized at a ratio of less than 0% by weight is also included.

In the polymer block B mainly composed of a hydrogenated butadiene monomer, the average amount of 1,2-bonds in the polymer block B before hydrogenation is from 62 to 99 mol%, and from 65 to 99 mol%. 99 mol%, preferably 7 mol%.
More preferably, it is 0 to 99 mol%. If it is less than 62 mol%, the adhesive strength will be insufficient. Further, as the amount of 1,2-bond increases, the compatibility with the propylene-based resin increases, and in the case of a surface protection film manufactured by a co-extrusion method using a propylene-based resin film as a base layer, the base material and the adhesive Between layers is improved. The term “based mainly on butadiene monomer” includes 50% by weight of butadiene and another monomer which undergoes, for example, living anion polymerization.
The case where the copolymerization is carried out at a ratio less than the above is also included.

In the hydrogenated block copolymer of the present invention, it is preferred that 90% or more of the olefinically unsaturated double bonds in the polymer block B before hydrogenation are hydrogenated. . If it is less than 90%, deterioration is easily caused by light, heat and the like. Further, the unsaturated double bond of the aromatic ring of the vinyl aromatic hydrocarbon compound in the polymer block A is preferably 20% or less based on the whole vinyl aromatic hydrocarbon compound.

The structure of the hydrogenated block copolymer is as follows:
For example, any shape such as linear, branched, radial, and comb shapes may be used, but at least two polymer blocks A mainly composed of a vinyl aromatic hydrocarbon compound monomer and a hydrogenated butadiene monomer are used. It must be composed of at least two main polymer blocks B.

Further, at least one of the blocks located at the terminal
Must be a polymer block B, the structure of which is of the general formula ABAB, or BABAB, or (BAB) nX, (Where n is an integer of 2 or more and X represents a coupling agent residue). The reason for being limited to the above is that the pressure-sensitive adhesive is softened over a wide range from low temperature to high temperature, and the rough surface fixability becomes good, and
This is because the removability is improved.

The ratio of the terminal polymer blocks B in the hydrogenated block copolymer is, for example, 0.1%.
1 to 9.1% by weight, preferably 0.3 to 7.5%.
%, More preferably 0.5 to 5.0% by weight. If it is less than 0.1% by weight, the tackiness becomes insufficient, and 9.1
If the content is more than 10% by weight, the cohesive force as an adhesive decreases,
When peeled off from the adherend, a problem that glue remains on the adherend surface may occur.

The hydrogenated block copolymer 2
MFR (JIS K7) at 30 ° C and 21.2N load
210) is limited to 1.0 to 20 g / 10 min. The reason is that if the MFR is less than 1.0 g / 10 minutes, the fluidity becomes poor, the moldability when forming a film becomes difficult, and the film becomes hard as a pressure-sensitive adhesive. This is because the adhesiveness to the body deteriorates.
If it exceeds 0 g / 10 minutes, the cohesive force of the pressure-sensitive adhesive will be reduced, and adhesive residue may be left on the adherend when peeled from the adherend. Note that the MFR is 2.0 to
8.0 g / 10 min is more preferable.

The pressure-sensitive adhesive in the present invention may be added to a resin mainly composed of the above-mentioned hydrogenated block copolymer, if necessary, as long as the performance of the pressure-sensitive adhesive is not impaired, a tackifier resin, an ultraviolet absorber, an antioxidant, An adhesion promotion inhibitor or the like can be added. Above all, it is preferable to add a tackifier resin in order to adjust the adhesive strength. If the compounding amount of the tackifying resin is too large, the cohesive force of the pressure-sensitive adhesive layer is reduced. Therefore, the amount is preferably 100 parts by weight or less based on 100 parts by weight of the hydrogenated block copolymer, and the tackifying effect is exhibited. Is added in an amount of 2 parts by weight or more based on 100 parts by weight of the hydrogenated block copolymer.

Examples of the tackifying resin include aliphatic petroleum resins, alicyclic petroleum resins, aromatic petroleum resins,
A rosin resin, a terpene resin, a phenol resin, a coumarone-indene resin, and the like are mentioned, and these may be hydrogenated as needed. These may be used alone or in combination of two or more.

Examples of the ultraviolet absorber include salicylic acid type, benzophenone type, benzotriazole type and the like, and as the product, for example, "Tinuvin 326" (trade name) manufactured by Ciba Specialty Chemicals Co., Ltd. is preferably used.

Examples of the antioxidant include phenol-based (monophenol-based, bisphenol-based, high-molecular phenol-based), sulfur-based, and phosphorus-based antioxidants. Examples of the products include products manufactured by Cibachiba Specialty Chemicals. "Irganox 1010" (trade name) or the like is preferably used because of its high effect on thermal degradation.

It is particularly preferable to add an adhesion promoting agent to the above-mentioned pressure-sensitive adhesive, since light peelability is maintained even after long-term storage and workability is excellent. If the added amount of the adhesion promotion inhibitor is too large, the initial adhesive strength becomes too small to cause floating, or to migrate to the adherend and contaminate it, based on 100 parts by weight of the hydrogenated block copolymer. The amount is preferably 10 parts by weight or less, and when added for exhibiting the effect of suppressing adhesion enhancement, the amount of addition is 0.01 part by weight or more based on 100 parts by weight of the hydrogenated block copolymer.

As the adhesion promoting agent, for example, fatty acid amide, polyethyleneimine long-chain alkyl graft, soybean oil-modified alkyd resin, tall oil-modified alkyd resin and the like are preferably used.

The thermoplastic resin used for the substrate layer in the present invention is not particularly limited, but those conventionally used as resins for surface protective films are preferred. For example, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene,
Ethylene-α olefin copolymer, propylene-α olefin copolymer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ethylene-n-butyl acrylate copolymer, polypropylene These may be used alone or in combination of two or more.

The thickness of the substrate layer varies depending on the purpose of use, but is preferably 20 to 100 μm. The thickness of the pressure-sensitive adhesive layer laminated on the base material layer is preferably 3 to 50 μm. The method for producing the surface protective film of the present invention is not particularly limited, for example, a method of laminating and integrating a substrate layer and an adhesive layer by coextrusion, and forming an adhesive layer by laminating after forming a substrate layer. Examples of the method include lamination and integration on a base material layer.

In the former method, known methods such as an inflation method and a T-die method are used. In the latter method, a solution coating method of applying an adhesive solution, a dry lamination method, and a melt extrusion method using a T-die. And an extrusion coating method using a T die. Among these, the hot melt extrusion method by coextrusion is preferable from the viewpoint of quality and economy. In the case of the solution coating method, in order to increase the bonding strength between the base material layer and the adhesive layer and to prevent the adhesive residue phenomenon, the thermoplastic resin used for the base material layer is preliminarily treated with a primer. Is more preferred.

(Function) In the surface protective film of the present invention, since the resin constituting the pressure-sensitive adhesive is composed of a hydrogenated block copolymer copolymerized into a suitable structure as described above, the pressure-sensitive adhesive has a low temperature. From a wide range of temperature to high temperature, and good sticking property to rough surface and low temperature sticking property. The mechanism of this action has not yet been fully elucidated, but by increasing the amount of 1,2-bonds in the polymer block B before hydrogenation, the flexibility of the polymer block B is increased by the so-called branched structure of the molecule. Is estimated to be improved. At the same time, by adjusting the MFR of the hydrogenated block copolymer to a suitable range, a surface protective film that can be easily peeled off from the adherend and can prevent dirt and adhesive residue on the adherend surface. It is possible to obtain.

[0030]

The present invention will be described below in more detail with reference to examples. A styrene-butadiene block copolymer was polymerized by anionic block copolymerization of styrene and butadiene with n-butyllithium as an initiator and tetrahydrofuran as a 1,2-bond amount regulator in a cyclohexane solvent.

Next, the obtained styrene-butadiene block copolymer was treated with bis (η ⁵ -cyclopentadienyl) titanium dichloride and n-butyllithium as hydrogenation catalysts at a hydrogen pressure of 0.49 MPa and a temperature of 50. Hydrogenation was performed at ° C. The polymer structure is the amount of monomer charged,
The order and molecular weight are controlled by the amount of catalyst, the amount of 1,2 bond is controlled by the amount of 1,2 bond regulator and polymerization temperature, and the hydrogenation rate is controlled by changing the hydrogenation time to prepare a hydrogenated block copolymer. did. Table 1 shows the structure and analysis values of the obtained copolymer.

[0032]

[Table 1]

(Method of Measuring Analytical Value) The hydrogenation rate, styrene content, and 1,2 bond content were measured using a nuclear magnetic resonance apparatus (NMR). 2. The MFR was measured under the conditions of a temperature of 230 ° C. and a load of 21.2 N according to JIS K7210.

(Examples 1-3, Comparative Examples 1-2) The hydrogenated block copolymer 1, the hydrogenated block copolymer 2, and the tackifier resin [Yasuhara Chemical Co., Ltd .; YS Resin Px1150 ”(trade name, softening point 115 ° C), soybean oil-modified alkyd resin [Arakawa Chemical Co., Ltd.,“ Arachid 251 ”(trade name)] as an adhesion promotion inhibitor, and an antioxidant [Ciba Specialty An adhesive layer made of "Ilganox 1010" (trade name) manufactured by Chemicals Co., Ltd., and a polypropylene resin [polypropylene manufactured by Grand Polymer, "S115" (trade name), MF
R = 12 g / 10 min (230 ° C.)] to obtain a 50 μm
A surface protection film was obtained in which a base material layer having a thickness of 10 μm and an adhesive layer having a thickness of 10 μm were integrally laminated.

The above-mentioned surface protective film was evaluated for the following properties, and the results are shown in Table 2. (1) Initial adhesive strength A stainless steel plate (SUS304, No. 280 polishing) under the environment of 0 ° C. and 23 ° C. and a relative humidity of 65% is applied to the surface protective film.
And acrylic coated steel plate (Ra = 1.3 μm)
After being left for 30 minutes in a state of being stuck at a speed of 300 mm / min using a pressure roller of 2,000 kg, JIS Z023
In accordance with No. 7, the 180-degree peel strength at a width of 25 mm was measured for each of the peel speeds of 0.3 m / min and 3 m / min. (2) Adhesion over time After the surface protective film was similarly affixed to the acrylic-coated steel sheet in an environment of 23 ° C. and a relative humidity of 65%,
After leaving for 7 days at 23 ° C. under a pressure of 0.49 MPa, decompressing, leaving for 30 minutes in an environment of 23 ° C. and 65% relative humidity, and then peeling strength at 180 ° in a 25 mm width according to JIS Z0237. Was measured.

(3) Contamination of the adherend At the time of measuring the peel strength in the above (1) and (2), the presence or absence of contamination on the surface of the adherend after peeling was visually observed. (4) Interlayer strength In the measurement of the peel strength in the above (1) and (2), the presence or absence of interlayer peeling at the interface between the base layer and the adhesive layer of the surface protective film after peeling is visually observed, and based on the following criteria. evaluated. ○: no delamination ×: delamination

[0037]

[Table 2]

[0038]

The surface protective film of the present invention has excellent initial adhesion to an adherend in a wide temperature range, and can be easily peeled at low or high speed when peeled from the adherend. Also, after peeling, no adhesive residue or stain is generated on the adherend surface. Further, since high-speed peeling is possible, there is a large practical effect that various workability is improved. Further, in the surface protective film of the present invention, it is possible to adopt a method of laminating a substrate layer and an adhesive layer by a co-extrusion method as a production method, in this case,
A protective film having improved adhesion strength between the base layer and the adhesive layer can be obtained in a simple molding step and in an environment in which an environmentally harmful organic solvent is not used (so-called solventless).

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 4F100 AB01C AB03C AK01A AK07A AK11B AK11K AK28B AK28K AL02B AR00B BA02 BA03 BA07 BA10A BA10C BA15 CA16B CA17B EH20 EJ91A GB90 JA06B JB16A JK05 JA13B04 A0201 BA172 BA201 BA202 DK011 DK012 DL151 DM011 DM012 EB031 EB032 ED152 EH012 HC10 JA09 JB09 KA26 LA01 LA06 LA11 MA02 MA08 MA10 MB03 NA12 NA15

Claims (3)

[Claims] 1. A surface protection film in which a base layer made of a thermoplastic resin and an adhesive layer made of an adhesive are laminated, wherein the resin constituting the adhesive is represented by a general formula ABA-
B or BABAB or (B-A-
B) nX, wherein A is a polymer block mainly composed of a vinyl aromatic hydrocarbon compound monomer, B is a polymer block mainly composed of a hydrogenated butadiene monomer, The average of the amount of 1,2-bonds before hydrogenation is 62 to 99 mol%, n is an integer of 2 or more, and X represents a residue of a coupling agent). A surface protective film mainly comprising a hydrogenated block copolymer having an MFR of 1.0 to 20 g / 10 minutes under the conditions. 2. The pressure-sensitive adhesive is a hydrogenated block copolymer 10.
2. The surface protective film according to claim 1, comprising 100 parts by weight or less of a tackifier resin with respect to 0 parts by weight. 3. The pressure-sensitive adhesive is a hydrogenated block copolymer 10.
The surface protective film according to claim 1 or 2, further comprising 10 parts by weight or less of an adhesion promotion inhibitor with respect to 0 parts by weight.