JPH01129085A - Surface-protective film - Google Patents

Abstract

PURPOSE:To provide the title film having a suitable initial adhesion, showing little rise in adhesion with the lapse of time, and being capable of production through co-extrusion, by forming a pressure-sensitive adhesive layer contg. polyethyleneimine having specific groups on one surface of a thermoplastic resin base film. CONSTITUTION:A pressure-sensitive adhesive layer contg. a mixture of a block copolymer of formula A-B-A(wherein A is a styrene polymer block; B is a butadiene polymer block, an isoprene polymer block or an olefin polymer block prepared by hydrogenation thereof) (e.g., a block copolymer of styrene polymer- ethylene.butylene compolymer-styrene polymer) with a tackifier (e.g., hydrogenated petroleum resin) and polyethyleneimine having higher alkyl groups introduced thereinto (e.g., octadecylisocyanate adduct of polyethyleneimine) is formed on one surface of a thermoplastic resin base film to produce a surface-protective film.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is used to temporarily adhere to the surface of a synthetic resin board, decorative plywood, metal plate, etc., and to prevent dust from adhering to the surface and preventing scratches. It relates to a surface protection film used for protection.

(Prior art) A surface protection film is made by forming an adhesive layer on one side of a base film made of thermoplastic resin such as polyolefin.
It is particularly desired to improve the adhesive layer in terms of adhesiveness when pasted on various articles and adhesive residue when peeled off from the article.

In addition, in manufacturing such surface protection films, a so-called co-extrusion method is often adopted, in which the adhesive composition and the thermoplastic resin of the base film are extruded together through a single mold slit to integrate them. Therefore, there is a demand for an adhesive composition suitable for melt extrusion.

As this type of surface protection film, for example,
No. 30911 and JP-A-61-103975 disclose that on one side of a base film made of a thermoplastic resin such as polyolefin, -nominal A-B-A (where A represents a styrene polymer block, B indicates a butadiene polymer block, an isoprene polymer block, or an ethylene-butylene copolymer block.) A surface protection film is disclosed in which a pressure-sensitive adhesive layer is formed by mixing a tackifier with a tackifier. In this case, the tackifier has the function of developing tackiness.

(Problems to be Solved by the Invention) However, with such a surface protection film, although the initial adhesion is good, the adhesion after application is significantly increased over time. Therefore, the surface protection film cannot be easily peeled off from the article after it has been used, and the peeling process is time-consuming.
Moreover, if the film is peeled off too quickly, there are problems in that adhesive remains or the base film stretches and breaks.

This tendency is particularly strong when the surface-protected article is exposed to relatively high temperatures, such as 60 to 80° C., or stored for a long period of time.

The present invention is intended to solve the above problems, and its purpose is to provide a surface protection film that has appropriate initial tackiness, exhibits little increase in tackiness over time, and can be manufactured by coextrusion. Our goal is to provide the following.

(Means for Solving the Problems) The surface protection film of the present invention includes a block copolymer of -typical A-B-A (where A is a styrene polymer) on one side of a base film made of a thermoplastic resin. (B represents a butadiene polymer block, an isoprene polymer block, or an olefin polymer block obtained by hydrogenating these), a tackifier, and a polyethyleneimine into which a higher alkyl group has been introduced. The above object is achieved by forming an adhesive layer made of a mixture of the following.

As the thermoplastic resin constituting the base film, olefin resins such as polyethylene and polypropylene are suitably used.

In the block copolymer of the above nominal A-B-A, the styrene polymer block A has an average molecular weight of 2000 to 10
A glass transition temperature of about 0,000 is preferable, and a glass transition temperature of 20° C. or higher is preferable.

Moreover, the butadiene polymer block, the isoprene polymer block, or the olefin polymer block B obtained by hydrogenating these has an average molecular weight of toooo to 300.
The glass transition temperature is preferably about -20°C or less. In particular, olefin polymer block B, which is made by hydrogenating and saturated butadiene polymer blocks and is made of ethylene-butylene copolymer with no residual double bonds, is suitable because it has excellent weather resistance and heat resistance. used for.

The preferable weight ratio of the above A component and B component is A
/B = 5/95 to 50150, more preferably A/B = 10/90 to 30/70. Examples of block copolymers of the above-mentioned A-B-A are Kraton G-1650, G-1652, and G-1 manufactured by 5hell Chemical Co., Ltd.
1657 and Califlex TR-1101STR-1
107, Fintack manufactured by Nippon Zeon Co., Ltd., etc.

Further, as the tackifier, those generally known as tackifiers such as rosin, modified rosin, petroleum resin, modified petroleum resin, terpene resin, coumaron indene resin, etc. are used. These tackifiers are the same as those mentioned above.
Preferably 10 to 150 parts by weight, more preferably 30 to 12 parts by weight, per 100 parts by weight of the B-A block copolymer.
0 parts by weight are mixed. If the amount is less than 10 parts by weight, the initial adhesiveness of the adhesive will be reduced, while if it is more than 150 parts by weight, the adhesive will become too hard and difficult to use.

The above polyethyleneimine into which a higher alkyl group is introduced preferably has an average molecular weight of 1,000 to 20,000, and the higher alkyl group is preferably introduced in an amount of 0.5 to 1.0 equivalent to the imine group of the polyethyleneimine.
More preferably, it is 0.7 to 1.0 equivalent. As the higher alkyl group, an alkyl group having 12 or more carbon atoms is generally preferred, and an octadecyl group is particularly preferred. In order to introduce a higher alkyl group into polyethyleneimine, for example, an excess of higher alkyl isocyanate is added to polyethyleneimine, and it can be easily introduced by an addition reaction.

The polyethyleneimine into which higher alkyl groups have been introduced is preferably mixed in an amount of 0.1 to 2.8 parts by weight per 100 parts by weight of the typical ABA block copolymer.

If it is less than 0.1 part by weight, the increase in tackiness over time cannot be significantly prevented. On the other hand, if it exceeds 2.0 parts by weight, a large amount of this bleeds onto the surface of the adhesive layer and contaminates the article to be pasted, which is not very preferable.

The surface protection film of the present invention is one in which the above-mentioned adhesive is laminated on one side of the base film, and any method may be adopted as the lamination method, for example, the thermoplastic resin forming the base film and the adhesive An example of this method is to co-extrude and laminate the materials.

The thickness of the base film and the adhesive layer may be appropriately determined depending on the application, but the thickness of the base film is generally 10 to 80 mm.
The thickness of the adhesive layer is generally 5 to 30 μ. In addition, a softener, an ultraviolet absorber, an antioxidant, etc. may be added to the adhesive layer as necessary.

(Function) The surface protection film of the present invention has an adhesive layer made of a mixture of a typical A-B-A block copolymer, a tackifier, and polyethyleneimine into which a higher alkyl group has been introduced. In particular, by mixing an appropriate amount of polyethyleneimine into which a higher alkyl group has been introduced, this specific polyethyleneimine bleeds onto the surface of the adhesive and moderately suppresses the physicochemical affinity with the article to be attached. It is thought that this prevents the increase in tackiness over time.

In addition, since a block copolymer of 100% A-B-A is used as the adhesive component and a tackifier is mixed therein, appropriate initial tackiness is imparted and anchoring with the base film is achieved. It has strong strength and does not leave adhesive residue, and has excellent melt extrusion properties.

(Jitsufuku example) The present invention will be explained in detail below.

1 to 4 F. As a block copolymer of the general formula A-B-A, a block copolymer of styrene polymer-ethylene/butylene copolymer-styrene polymer (Kraton G-1657,5he
ll chemical company) and hydrogenated petroleum resin (
Niscolec 5300 (Exxon Chemical Co.) and octadecyl isocyanate-adducted polyethyleneimine (referred to as PBIOJ with a melting point of 60°C) as polyethyleneimine into which a higher alkyl group has been introduced were blended in the proportions shown in Table 1, and five types of adhesives were prepared. A composition was prepared.

In addition, the above adhesive composition contains a polymeric phenolic antioxidant (Irugalanox 101) as an antioxidant.
0.0, Nippon Ciba Geigy Co., Ltd.) were added in an amount of 0.5 parts by weight.

Five types of surface protection in which a 15μ adhesive layer is formed on one side of a base film made of 60μ low density polyethylene by co-extruding the above adhesive composition and low density polyethylene (melt index 7g/10 minutes). produced a film. Its coextrudability was good.

These five types of surface protection films were each pressed with a 2 kg press roll at 23°C and attached to the surface of a stainless steel plate. For these five types of samples, the initial adhesive strength (23°C) was determined by a 180° angular constant speed peel strength test (pulling speed 300 k/min), and the adhesive strength over time under no load (23°C x 10
(60 days to 60 days) and high temperature aging adhesive strength under no load (60℃
x 10 days). The results are shown in Table 1.

(Hereinafter, the margins) (Effects of the invention) The surface protection film of the present invention is constructed as described above, and in particular, since polyethyleneimine into which a higher alkyl group has been introduced is mixed as an adhesive component, a suitable amount of It has initial tackiness, exhibits little increase in tackiness over time or tackiness over time at high temperatures, and exhibits excellent adhesive performance and easy peeling performance without leaving adhesive residue even after time.

Moreover, the adhesive is suitable for coextrusion with the thermoplastic resin of the base film, and the surface protection film can be easily manufactured.

Claims (1)

[Claims] 1. On one side of a base film made of a thermoplastic resin, a block copolymer of the general formula A-B-A (where A represents a styrene polymer block, B represents a butadiene polymer block, an isoprene polymer block, or an olefin polymer block obtained by hydrogenating these), a tackifier, and polyethyleneimine into which a higher alkyl group has been introduced. surface protection film.