JP2003055619A - Surface-protective film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-protective film which can be temporarily adhered to a substance to give good adhesiveness without a particularly high adhesive pressure and can be released from the substance with good releasability. SOLUTION: The surface-protective film comprises a base material layer comprising a polyolefin resin and an adhesive layer laminated on the base material layer, wherein the adhesive layer comprises the hydrogenated product of a styrene-conjugated diene elastomer containing a. liquid polyolefin glycol. The surface-protective film is a surface-protective film as defined above, wherein the adhesive layer comprises 10-80 parts by weight of the liquid polyolefin glycol relative to 100 parts by weight of the hydrogenated product of the styrene-conjugated diene elastomer.

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 surface of an adherend such as a steel plate, a metal plate, a coated steel plate, a synthetic resin plate, a decorative plywood, a coated resin plate and various name plates. The present invention relates to a surface protection film used to prevent dust from adhering to or scratching these surfaces by temporary attachment.

[0002]

2. Description of the Related Art When processing or transporting steel plates, metal plates, coated steel plates, synthetic resin plates, decorative plywood, coated resin plates, various name plates, etc., their surfaces may become dirty or scratched. In order to prevent this, a surface protection film is often used.

The surface protective film usually has a structure in which an adhesive layer is formed on one side of a base material layer made of a thermoplastic resin or paper. When used, the adhesive layer temporarily protects the surface of the adherend such as steel plate and metal plate to protect the surface of the adherend and protects the adherend from dirt and scratches. To do. When the adherend is used, the surface protective film is peeled off from the surface of the adherend. Therefore, the surface protective film needs to have a suitable adhesiveness such that it can be easily temporarily attached to the surface of the adherend and, at the same time, can be easily peeled off from the surface of the adherend after use. Moreover, it is required that the surface of the adherend after peeling is not contaminated.

In order to cope with such a problem, for example, in JP-A-61-1103975, "AB-
A (however, A represents a styrene polymer block and B represents a copolymer block of ethylene and butylene) (hereinafter, S
100 parts by weight of EBS) and tackifying resin 0-80
An adhesive film for surface protection (surface protection film), which is formed by forming a pressure-sensitive adhesive layer made of a composition containing parts by weight on a polyolefin resin film (base material layer), is disclosed.

Since the surface protection film disclosed above uses a polyolefin resin base material layer, it can be incinerated after use, and since it uses an adhesive containing SEBS as a main component, It is said that the pressure sensitive adhesive layer has low temperature sensitivity, good removability and is less likely to cause adhesive residue.

However, in the case of the above-mentioned surface protective film using an adhesive composed of SEBS and tackifying resin,
If the addition amount of the tackifying resin is less than 10 parts by weight with respect to 100 parts by weight of SEBS, sufficient tack and adhesive force to the surface of various materials (objects to be protected) including metal plates cannot be obtained, so that the surface protection film is temporarily used. The surface protection film tends to peel off during storage or transportation of the protected object that has been worn,
There is a problem that a sufficient surface protection function cannot be obtained. On the other hand, if the addition amount of the tackifying resin to 100 parts by weight of SEBS is 10 parts by weight or more, the adhesiveness increases, but the elastic modulus of the adhesive at room temperature improves, so that external force such as increasing the pressure bonding force at the time of sticking is applied. Was needed. Then, if the pressure bonding force is increased by an external force, the adhesion progress is likely to occur over time, and there is a problem that the surface of the protected object after the surface protective film is peeled off is liable to cause fog and adhesive residue phenomenon.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems and, at the time of temporary attachment to an adherend, provides good adhesiveness without particularly increasing the pressure-bonding force and at the same time from the adherend. It is an object of the present invention to provide a surface protective film having good releasability upon peeling.

[0008]

The surface protective film according to claim 1 is a base layer made of a polyolefin resin,
It is characterized in that an adhesive layer comprising a hydrogenated product of a styrene-conjugated diene elastomer containing a liquid polyolefin glycol is laminated.

The surface protective film according to claim 2 is the surface protective film according to claim 1, wherein the adhesive layer comprises 10 parts by weight of liquid polyolefin glycol based on 100 parts by weight of the hydrogenated styrene-conjugated diene elastomer. ~ 8
It is characterized by containing 0 parts by weight.

The present invention will be described in more detail below. Examples of the hydrogenated product of the styrene-conjugated diene elastomer used in the present invention include, for example, JP-A-61-1039.
The ABA type as described in Japanese Patent Publication No. 75 is mentioned. Here, A is a styrene polymer block and B is a conjugated diene polymer block. The preferred molecular weight range of the styrene polymer block A is 2000-1.
It is about 00000, and its preferable glass transition temperature is 20 ° C. or higher. The preferred molecular weight range of the conjugated diene polymer block B is about 10,000 to 300,000, and its preferred glass transition temperature is -20 ° C or lower. A preferred weight ratio of A and B is A / B = 5 / 95-
It is 50/50. Further, in addition to the ABAA type, AB may be further blended. The definitions of A and B in AB are the same as above, and the weight ratio of A and B is preferably A / B = 5/95 to 50/50.

The above general formula A-B-A or A-
B in the block copolymer represented by B is preferably a butadiene polymer block or an isoprene polymer block, and these are preferably hydrogenated polymer blocks.

As the hydrogenated product of the styrene-conjugated diene elastomer used in the present invention, the block copolymer represented by the above general formula AB is coupled with a coupling agent (AB). ) N-X (n is an integer of 2 or more, X is a coupling agent residue).

Another example of the hydrogenated product of the styrene-conjugated diene elastomer used in the present invention is the general formula A ¹ -B ¹ -A ¹ -B ¹ or B ¹ -A ¹ -B ^1-.
A ¹ -B ¹ or (B ¹ -A ¹ -B ¹ ) n-X, (wherein A ¹ is a polymer block mainly composed of styrene monomer, B ¹ is hydrogenated) A polymer block composed mainly of a butadiene monomer, wherein the average 1,2-bond amount before hydrogenation is 62 to 99 mol%, n is an integer of 2 or more,
X represents a coupling agent residue), and in these, preferably 230 ° C., load 2
MFR in the condition of 1.2N is 1.0 to 20 g / 10
Those that are minutes.

The hydrogenated block copolymer is composed of a styrene polymer block A ¹ and a polymer block B ¹ mainly containing a hydrogenated butadiene monomer.

The content of the styrene monomer in the above block copolymer is preferably 10 to 25% by weight, more preferably 12 to 25% by weight.

In the polymer block B ¹ mainly composed of hydrogenated butadiene monomer, the average 1,2-bond amount of the polymer block B ¹ before hydrogenation is 62 to 99.
Mol%, preferably 65 to 99 mol%, more preferably 70 to 99 mol%. The term "mainly composed of butadiene monomer" means
It also includes a case where butadiene is copolymerized with other monomers, for example, living anionically polymerized, in a proportion of less than 50% by weight.

In the hydrogenated block copolymer of the present invention, 90% or more of the olefinically unsaturated double bonds in the polymer block B ¹ before being hydrogenated are hydrogenated. preferable. If it is less than 90%, deterioration is likely to occur due to light, heat and the like.

The structure of the hydrogenated block copolymer is
For example, any shape such as linear, branched, radial, or comb shape may be used, but at least two polymer blocks A ¹ mainly composed of styrene monomer and at least mainly hydrogenated butadiene monomer. 2 polymer blocks B
Must consist of ^one .

At least one of the blocks at the end
The individual must be a polymer block B ¹ , and the structure is represented by the general formula A ¹ -B ¹ -A ¹ -B ¹ or B ¹ -A ^1-.
B ¹ -A ¹ -B ^{1, or, (B 1 -A 1 -B 1} ) n-
X, where n is an integer of 2 or more and X is 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 a low temperature to a high temperature, and the adhesiveness on the rough surface is good, and the removability is good.

The proportion of the polymer blocks B ^{1 at the} ends in the hydrogenated block copolymer is, for example, 0.1 to 9.1% by weight, preferably 0.3 to
It is 7.5% by weight, and more preferably 0.5 to 5.0% by weight.

In addition, 2 of the above hydrogenated block copolymers
MFR at 30 ° C and 21.2N load (JIS K7
210) is preferably 1.0 to 20 g / 10 minutes, and more preferably 2.0 to 8.0 g / 10 minutes.

Styrene-conjugated dienes used in the present invention
Still another example of hydrogenated elastomer type elastomer is
Tylene polymer block A²And styrene and conjugated dienes
Random block copolymer B²Consisting of A²-B²
Block copolymer, or optionally styrene
Of the conjugated diene and styrene
A consisting of C²-B²-C block copolymer, if
Ku, styrene polymer block A²Consisting of A²-B²
-A²It is a block copolymer. Also shown in the following general formula
So that you can repeat and couple these
It may be one. General formula (A²-B²) N (A²-B²) N-X (A²-B²-C) n-X (A²-B²-A²) N-X (In the formula, n is an integer of 2 or more, and X is a coupling agent residue.
Represent ) Among the above block copolymers, preferably A²-B
²-C or A²-B ²-A²Is a block copolymer
It

The above A ² -B ² -C or A ² -B ² -A
The content of styrene, which is a constituent of the ^two- block copolymer, and the conjugated diene is preferably 5:95 to 60:40 by weight, and more preferably 7:93 to 40:60.

Further, the above styrene polymer block A
² and the bond content of styrene in the tapered copolymer block C is preferably 3 to 50% by weight of all monomers,
More preferably 5 to 40% by weight, still more preferably 5 to
It is 25% by weight.

Further, the vinyl bond content of the conjugated diene moiety in the block B ² is preferably more than 60%,
It is more preferably 70% or more, still more preferably 80% or more. When the vinyl bond content is 60% or less, the tackiness is insufficient. The vinyl bond as used herein refers to a monomer unit obtained by polymerizing a conjugated diene compound with a double bond at a 1,2- or 3,4-bond position.

It is preferable that at least 80% of the double bonds of the conjugated diene moiety in the block B ^{2 be} saturated by hydrogenation, more preferably 90% or more, and further preferably 95 to 100%. If the proportion of hydrogenation is less than 80%, the heat resistance and weather resistance will be poor.

The weight average molecular weight of the hydrogenated product of the styrene-diene copolymer is preferably 50,000 to 400,000, and more preferably 80,000 to 200,000 in terms of polystyrene by gel permeation chromatography.

The adhesive layer in the present invention comprises a hydrogenated product of a styrene-conjugated diene elastomer containing liquid polyolefin glycol. The liquid polyolefin glycol is added for the purpose of giving tackiness. The above liquid polyolefin glycol has about 150 carbon atoms.
Among the polyhydric alcohols having 200 polyolefin saturated hydrocarbon segments as the molecular skeleton and having a hydroxyl group at the molecular end, those which are liquid at room temperature and usually have a hydroxyl value of 3
It is about 5 to 55 KOHmg / g. From the viewpoint of weather resistance and the like of the compound, the iodine value showing the degree of saturation of the hydrocarbon segment is preferably as low as possible, and is preferably about 5 g / 100 g or less. Examples of commercially available products include "Polytail" series manufactured by Mitsubishi Chemical Corporation.

When the amount of the liquid polyolefin glycol used is less than 10 parts by weight based on 100 parts by weight of the hydrogenated product of the styrene-conjugated diene elastomer, the desired effect is hardly exhibited, and when it exceeds 80 parts by weight. Since the cohesive force of the pressure-sensitive adhesive may be reduced and it may cause adhesive residue during re-peeling, 10 to 80 parts by weight of liquid polyolefin glycol is added to 100 parts by weight of hydrogenated styrene-conjugated diene elastomer. preferable.

In the pressure-sensitive adhesive layer of the present invention, in addition to the above-mentioned components, if necessary, for example, a homopolymer of α-methylstyrene or α-methylstyrene, as long as the object of the present invention is not hindered.
-Removability improving agent such as α-methylstyrene-based resin such as copolymer of methylstyrene and terpenes, fatty acid amide, etc., for example, time-dependent adhesive strength of higher alkyl group-introduced polyethyleneimine (adhesion with time) Strength) anti-stabilizer, filler, softener, plasticizer, surfactant, coupling agent,
One kind or two or more kinds of various additives such as an antioxidant (antiaging agent), a heat stabilizer, a light stabilizer, an ultraviolet absorber and a colorant may be contained.

The polyolefin resin used for the base material layer in the present invention is mainly composed of an α-olefin polymer resin such as a polyethylene resin or a polypropylene resin. Polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, ethylene-α-olefin copolymer, polypropylene (homopolymer, random copolymer,
(Including block copolymers), propylene-α-olefin copolymers, ethylene-vinyl acetate copolymers, ethylene-methyl methacrylate copolymers, ethylene-ethyl acrylate copolymers, ethylene-n-butyl acrylate copolymers Examples include coalescence. These polyolefin resins may be used alone or in combination of two or more kinds.

The thickness of the base material layer varies depending on the purpose of use, but is preferably 20 to 100 μm. The thickness of the 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 comprises:
The method is not particularly limited, for example, a method of laminating and integrating a base material layer and an adhesive layer by coextrusion, a method of forming an adhesive layer on a base material layer by laminating after forming a base material layer, and the like. Is mentioned. In the former method, known methods such as an inflation method and a T-die method are used, and in the latter method, a solution coating method for coating an adhesive solution, a dry lamination method, a melt extrusion method using a T-die, a T-die method. The extrusion coating method and the like are used. Of these, the hot melt extrusion method by coextrusion is preferable because the production apparatus and production process are simple, the productivity is excellent, and the lamination strength is higher.

The surface protection film of the present invention is mainly used for surface protection of steel plates and metal plates, but is not limited to these applications and other materials (objects to be protected).
It may also be used for surface protection.

(Function) In the surface protective film of the present invention, since the adhesive layer is composed of the hydrogenated product of the styrene-conjugated diene elastomer containing the liquid polyolefin glycol, the pressure-sensitive adhesive force is required for the temporary attachment to the adherend. The adhesiveness is good even if it is not particularly increased, and the peelability from the adherend is good.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION The following examples are given to illustrate the present invention in more detail, but the present invention is not limited to these examples.

(Example 1) Hydrogenated resin (SEBS) of styrene-butadiene-styrene block copolymer (trade name "Clayton G1657", manufactured by Shell Japan)
An adhesive consisting of 100 parts by weight and 10 parts by weight of liquid polyolefin glycol (trade name "Polytail HA", manufactured by Mitsubishi Chemical Co., Ltd.), and a linear low-density polyethylene (trade name "M12", for a base material layer, (Manufactured by Mitsui Chemicals, Inc.) was extruded by a two-layer coextrusion method to obtain a surface protective film in which an adhesive layer having a thickness of 8 μm was laminated on one surface of a base material layer having a thickness of 60 μm.

(Examples 2 to 4) Liquid polyolefin glycol "Polytail HA" in the amount shown in Table 1 in the adhesive.
A surface protective film was obtained in the same manner as in Example 1 except that was added.

(Comparative Example 1) A surface protective film was obtained in the same manner as in Example 1 except that the liquid polyolefin glycol "Polytail HA" was not added to the adhesive.

(Comparative Examples 2 to 4) Liquid polyolefin glycol "Polytail HA" was not added to the pressure-sensitive adhesive, but instead the amount of alicyclic hydrogenated petroleum resin (commercial product) shown in Table 1 was used as the tackifying resin. A surface protective film was obtained in the same manner as in Example 1 except that the name "Alcon P125", manufactured by Arakawa Chemical Industries, Ltd.) was added.

The adhesive strength (SP adhesive strength) of the surface protection films obtained in Examples 1 to 4 and Comparative Examples 1 to 4 to a stainless steel plate (SUS plate) was evaluated by the following method.
The results are shown in Table 1.

SP adhesive strength: In accordance with JIS Z-0237 "Adhesive tape / adhesive sheet test method", 180 degree angle peeling adhesive strength (N /
25 mm) was measured. In addition, as a pressure bonding condition at the time of preparing the sample, both 49 N / cm and 196 N / cm were tested.
Moreover, after sticking the surface protection film on the SUS plate under the pressure bonding condition of 196 N / cm and leaving it at 40 ° C. for 1 month, the 180 ° angle peeling adhesive force (N / 25 mm) was similarly measured (hereinafter, this is It is called SP adhesive strength over time).

[0043]

[Table 1]

As is clear from Table 1, the surface protective films of Examples 1 to 4 according to the present invention were good or excellent in tackiness (temporary adhesion) to the SUS plate even under low pressure bonding conditions (49 N / cm). Sex). In addition, there was little progress of adhesion over time.

On the other hand, the surface protective film of Comparative Example 1 in which the liquid polyolefin glycol was not added was S
The adhesive strength to the US plate was poor. Further, the surface protective films of Comparative Examples 2 to 4 to which the tackifying resin was added instead of the liquid polyolefin glycol were not sufficiently adhered under the low pressure bonding condition (49 N / cm) in Comparative Example 2. Inferior attachment was observed, and in Comparative Examples 3 and 4, the adhesion progressed with time.

[0046]

As described above, the surface protective film of the present invention comprises a base material layer made of a polyolefin resin, and an adhesive layer made of a hydrogenated styrene-conjugated diene elastomer containing a liquid polyolefin glycol. Since they are laminated, they have good adhesiveness even when the pressure-bonding force is not particularly increased at the time of temporary attachment to the adherend, and have good releasability when peeled from the adherend. Therefore, the surface protection film of the present invention is most suitable for surface protection of steel plates and metal plates. Further, it is not limited to these applications, and may be used for surface protection of other materials (objects to be protected).

Continued front page    F-term (reference) 4F100 AB01C AH02B AK01C AK03A                       AK54B AK63 AK73B AL05B                       AL06B AL09B BA02 BA03                       BA07 BA10A BA10C HB00                       JL13B YY00B                 4J004 AA05 AA17 AB01 CA04 FA04                       FA08                 4J040 CA081 DB051 DM011 HB15                       JA09 JB09 LA06 MA02 PA23

Claims (2)

[Claims] 1. A surface protective film comprising a base material layer made of a polyolefin resin and an adhesive layer made of a hydrogenated product of a styrene-conjugated diene elastomer containing a liquid polyolefin glycol. 2. The surface protective film according to claim 1, wherein the adhesive layer contains 10 to 80 parts by weight of liquid polyolefin glycol with respect to 100 parts by weight of hydrogenated styrene-conjugated diene elastomer.