JPH09188857A - Surface protective film and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface protective film which is excellent in the stability of initial stickiness and stickiness after aging and does not leave behind any adhesive when peeled from an adherend. SOLUTION: This film comprises a polyolefin resin film as the substrate and a self-adhesive layer formed on one side thereof. The self-adhesive layer mainly comprises a block copolymer of an A-B-A type (wherein A is a styrene polymer block; and B is an optionally hydrogenated butadiene or isoprene polymer block) and contains a tackifier. The substrate and/or the self-adhesive layer contains an additive X which is a polyethyleneimine and/or polyvinyl alcohol having a mol.wt. of 8,000-100,000 and an additive Y which is a fatty acid amide having a mol.wt. of 1,000 or lower. The amts. of the additives X and Y present in the substrate and/or the self-adhesive layer are 20-400mg/m<2> and 10-300mg/m<2> , respectively.

Description

Detailed Description of the Invention

The present invention relates to a surface protection film, and more specifically, it protects the surface of a synthetic resin plate, a decorative plywood, a metal plate, etc. by temporarily adhering it to prevent the adhesion of dust and scratches. The present invention relates to a surface protection film.

[0002]

2. Description of the Related Art A surface protective film having an adhesive layer formed on one surface of a base film made of a thermoplastic resin such as polyolefin has come to be widely used as a surface protective film for synthetic resin plates, decorative plywood, metal plates and the like. However, many problems still remain with respect to the adhesive properties, such as excess and deficiency of the adhesive force of the adhesive layer and adhesive residue on the surface of the adherend after use.

A release agent is added to the pressure-sensitive adhesive layer and bleeds out on the surface of the pressure-sensitive adhesive layer. The above-mentioned problems such as excessive or insufficient adhesive strength of the pressure-sensitive adhesive layer and adhesive residue on the surface of the adherend after use. Many attempts have been made to eliminate this problem.
However, the molecular weight of the release agent is small, and, when the melting point is low, the adhesive performance of the resulting surface protective film sharply decreases with time, and easily peeled from the adherend that is temporarily attached, When the melting point is increased, the effect of suppressing the progress of adhesion over time decreases, and after use, it becomes difficult to peel off from the adherend, and even if peeling is possible, adhesive residue tends to remain. On the other hand, when the release agent has a large molecular weight, the amount of the release agent that bleeds out to the surface of the adhesive layer decreases, so that the effect of suppressing the adhesion promotion cannot be obtained, and the adhesion promotion progresses more and more with the passage of time, and after use It becomes difficult to peel off from the body, and even if it can be peeled off, glue remains.

The inventors of the present invention have previously disclosed Japanese Patent Laid-Open No. 1-12908.
In Japanese Patent Laid-Open No. 5 (1994), a block copolymer of the general formula A-B-A (where A is a styrene polymer block, B is a butadiene polymer block, isoprene) is formed on one side of a base film made of a thermoplastic resin. A polymer block or an olefin polymer block obtained by hydrogenating these), a tackifier, and a surface on which a pressure-sensitive adhesive layer formed by mixing a higher alkyl group-introduced polyethyleneimine is formed. We developed a protective film and realized some improvement.

[0005]

In view of the above facts, the present invention has been made to further improve the stability over time, and the purpose thereof is to provide an initial adhesive force to an adherend. Another object of the present invention is to provide a surface protective film which maintains stable adhesive strength over time and has no adhesive residue when peeled from an adherend after use.

[0006]

The present invention according to claim 1 provides a block copolymer of the general formula A-B-A (where A is styrene) on one surface of a substrate layer made of a polyolefin resin film. A polymer block, B is a butadiene polymer block, an isoprene polymer block or an olefin polymer block obtained by hydrogenating these) is a main component, and an adhesive layer containing a tackifier is provided. In the surface protective film, the base material layer and / or the pressure-sensitive adhesive layer contain the following two kinds of additives X and Y, and the additive X has a melting point of 60 to 100 ° C. and a molecular weight of 8,000 to 100,000. Which is a polyethylenimine and / or polyvinyl alcohol into which a higher alkyl group is introduced, wherein the additive Y has a melting point of 120 to 180 ° C. and a molecular weight of 1000 or less. There carbon atoms are fatty acid amide is 14 to 23, and, in a total amount per surface area of the base layer and / or adhesive layer, additives X20～400mg /
The gist of the surface protective film is characterized by containing m ² and the additive Y10 to 300 mg / m ² .

The invention according to claim 2 is characterized in that a base material layer made of a polyolefin resin film and an adhesive layer are integrally laminated by multilayer extrusion molding to form a film. The gist of the invention is a method of manufacturing a protective film.

According to the third aspect of the present invention, when a base material layer made of a polyolefin resin film and an adhesive layer are integrally laminated by multi-layer extrusion molding to form a film, they are extruded from a multi-layer extrusion molding die. Within 6 seconds after extruding the film, 6
The method for producing a surface protective film according to claim 1 or 2 is characterized by cooling to 0 ° C or lower.

A polyolefin resin film is used for the base material layer of the present invention, and the polyolefin resin is not particularly limited, but examples thereof include low density polyethylene, medium density polyethylene, high density polyethylene, and Examples include chain low-density polyethylene and polypropylene (homopolymers and block copolymers). Two or more of the above polyolefin-based resins may be appropriately mixed and used. Further, in the above polyolefin resin, 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 (random copolymer)
One or more of the above may be appropriately mixed and used.

The pressure-sensitive adhesive used in the pressure-sensitive adhesive layer of the present invention is a block copolymer having the general formula ABA (where A is a styrene polymer block, B is a butadiene polymer block and isoprene polymer). Block or a olefin polymer block obtained by hydrogenating these) as a main component, a tackifier and a polyethyleneimine into which a higher alkyl group having a melting point of 60 to 100 ° C. and a molecular weight of 8000 to 100,000 is introduced, and Additive X composed of polyvinyl alcohol and / or a melting point of 120 to 180
It contains an additive Y consisting of a fatty acid amide having a molecular weight of 1000 or less and a carbon number of 14 to 23 at a temperature of C.

A block copolymer of the above general formula ABA (where A is a styrene polymer block and B is a styrene polymer block).
Means a butadiene polymer block, an isoprene polymer block or an olefin polymer block obtained by hydrogenating these), for example, styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene-styrene block. Copolymer (SBS),
Styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene-propylene-
Examples thereof include styrene block copolymer (SEPS).

In the surface protective film of the present invention according to claim 1, the additives X and Y are contained in the base material layer and / or the adhesive layer, but the total amount of the additives X and Y is Is the additive X20 to 400 per surface area of the adhesive layer.
It is limited to mg / m ² and additives Y10~300mg / m ^2. Further, the additives X and Y compounded in the base material layer and / or the adhesive layer are contained in the base material layer and / or
Alternatively, it may be added to the adhesive layer in an arbitrary ratio. That is, the total amount of the additives X and Y may be contained in the base material, or only one of the additives X or Y may be contained in the base material layer, and the mixture of the additives X and Y may be added. It may be contained by being distributed to the base material layer and the adhesive layer in a fixed ratio.

The base material layer may be composed of a single layer, but it is an intermediate layer between the polyolefin resin film layer not containing the additives X and Y forming the outermost layer and the outermost layer and the adhesive layer. It may be composed of two or more composite layers composed of a polyolefin resin film layer in which the additives X and Y are contained in the layers. The intermediate layer consisting of the polyolefin-based resin film layer containing the additives X and Y, for example, from the polyolefin-based resin film layer not containing the additives X and Y forming the outermost layer toward the adhesive layer, sequentially, It may be composed of two or more composite layers in which the concentrations of the additives X and Y increase.

The tackifier is not particularly limited, and examples thereof include rosin, modified rosin, terpene resin, coumarone indene resin, petroleum resin, and modified petroleum resin. The tackifier has the general formula AB-
It is preferably used in an amount of 1 to 20 parts by weight, more preferably 3 to 20 parts by weight, based on 100 parts by weight of the block copolymer of A.

The additive X has a melting point of 60 to 100 ° C.,
It is composed of polyethyleneimine and / or polyvinyl alcohol into which a higher alkyl group having a molecular weight of 8000 to 100,000 is introduced. If the melting point of the additive X is less than 60 ° C. or the molecular weight is less than 8,000, the rate of bleeding out to the surface of the adhesive layer is high, the initial adhesive strength and the adhesive strength with time are significantly reduced, and conversely. , Melting point 100
When the temperature exceeds 0 ° C or the molecular weight exceeds 100,000, the rate of bleeding out to the surface of the adhesive layer is slow, and the required amount of the additive X cannot be bleed out to the surface of the adhesive layer.

The additive Y has a melting point of 120-18.
It is composed of a fatty acid amide having a molecular weight of 1,000 or less at 0 ° C. and 14 to 23 carbon atoms. The melting point of the additive Y is 12
When the temperature is lower than 0 ° C, the rate of bleed-out to the surface of the pressure-sensitive adhesive layer is high, and the adhesive strength over time cannot be stably maintained. On the contrary, the melting point exceeds 180 ° C and the molecular weight is 10
When it exceeds 00, the speed of bleeding out to the surface of the adhesive layer is slow, the necessary amount of the additive Y is not bleed out to the surface of the adhesive layer, and as a result, the adhesive strength over time cannot be stably maintained. .

The required amounts of the additives X and Y bleed out to the surface of the adhesive layer for a long period of time, but the controlled bleedout has a large proportion of bleeding out to the surface of the adhesive layer during cooling in multilayer extrusion molding. Additive X and additive Y, which has a large ratio of slowly bleeding out to the surface of the adhesive layer after cooling, are compounded in a content within the above range so that the initial adhesive strength and adhesive strength over time of the adhesive layer are stably maintained. It is presumed that the existence of this contributes.

The bleed-out during cooling in the above-mentioned multilayer extrusion molding mainly depends on the melting point and the molecular weight of the additive contained therein, and the additive Y contains the multilayer extrusion molding metal at a molding temperature of about 180 ° C. Migration to the surface of the adhesive layer occurs only in the initial stage of extrusion from the mold, and a large amount of bleed-out does not occur during multilayer extrusion molding.
80 ° C, 14 to 2 carbon atoms having a molecular weight of 1000 or less
It is presumed that the fatty acid amide of 3 is selected to exhibit the above effect.

Further, after the surface protective film of the present invention is attached to an adherend, migration of the pressure-sensitive adhesive becomes large at 30 ° C.
In the above environment, in order to suppress the adhesion promotion due to the increase in the adhesion area, the additive X has a melting point of 60 to 100 ° C. and a molecular weight of 8000 to 100000 in particular.
It is presumed that polyethyleneimine and / or polyvinyl alcohol into which a higher alkyl group is introduced are selected to exhibit the above effect. Additives X and Y as described above
By using together, without significantly reducing the initial adhesive strength of the adhesive layer synergistically, and suppressing the adhesion accelerating by migration of the adhesive in a short period of time or at low temperature, the initial adhesive force and aging The adhesive strength can be maintained stably.

If necessary, a surfactant, a softening agent, a filler, a colorant and the like can be added to the above-mentioned base material layer and the adhesive layer, as long as they do not depart from the spirit of the present invention.

The method for producing the surface protective film of the present invention comprises:
The polyolefin resin film of the base material layer and the above general formula A
-Mainly composed of a block copolymer composed of BA and a tackifier.
The above-mentioned additive X and Y are added to the above-mentioned base material layer in the adhesive layer as a component.
And / or the pressure-sensitive adhesive layer, the surface of the substrate layer and / or the pressure-sensitive adhesive layer.
Additive X20-400 mg / m2 in total amount per area ^Two
And additive X10 to 300 mg / m^TwoContains a lot of
A film is formed by laminating layers integrally by layer extrusion molding.
You.

As described above, each layer such as the base material layer and the adhesive layer of the surface protective film of the present invention is kept at a high pressure while being thermoplasticized in the extruder, and the inside of the system of each layer is uniform. Is held in the multi-layer extrusion molding die and is discharged to the atmospheric pressure environment, and after cooling, a slight flow of the additives X and Y to the surface of the adhesive layer occurs due to the difference in the internal and external conditions.
The molding temperature applied to each layer such as the base material layer and the pressure-sensitive adhesive layer is relatively low and is rapidly cooled, so that the additives X and Y added to the surface of the pressure-sensitive adhesive layer in the manufacturing process of the surface protective film. The amount of bleed-out can be controlled easily, the initial adhesive strength and the adhesive strength with time to the adherend are maintained stably, and surface protection without adhesive residue when peeled from the adherend after use The film can be obtained. When the adhesive layer is provided on one surface of the base material film even with the same composition by a coating method or the like, the base material film and the adhesive layer are exposed to a high temperature in the drying step. In the manufacturing process, it becomes impossible to control the amount of bleed-out to the surface of the adhesive layer, and as a result, it is not possible to obtain a surface protective film that stably maintains the initial adhesive strength and the adhesive strength over time.

Further, according to the method for producing a surface protective film of the present invention, when a pressure-sensitive adhesive layer is formed on one surface of a base material layer made of a polyolefin resin film by multilayer extrusion molding, it is extruded from a multilayer extrusion molding die. The film is cooled to 60 ° C. or less within 2 seconds after extrusion. The cooling condition is 60 ° C
When the temperature exceeds 60 ° C or exceeds 2 seconds for cooling to 60 ° C or less, the amount of bleed-out to the surface of the adhesive layer increases, and various rolls including a cooling roll of a multilayer extrusion molding machine contacting this increase The additives mainly composed of the additives X and Y plate out and adhere to the various rolls to contaminate them, thereby deteriorating the surface condition of the obtained surface protective film and causing blocking. Of course, the adhesive property of the obtained surface protection film is deteriorated.

Further, since the method for producing the surface protective film of the present invention is constructed as described above, it is easy to bleed out the amount of the additives X and Y to the surface of the adhesive layer in the production process of the surface protective film. In addition to being able to control the surface, the interface of the base material layer and the adhesive layer are intruded into each other and firmly laminated, so that the above-mentioned initial adhesive strength and adhesive strength with time are stably maintained. The film can be easily manufactured.

The surface protective film of the present invention may be wound into a roll and stored as a long film, or may be stored as a single sheet. In any case, a separator may be temporarily attached to the surface of the pressure-sensitive adhesive layer to protect the pressure-sensitive adhesive layer. As the separator, for example, a polyester film such as polyethylene terephthalate, one surface of a polyolefin film such as polyethylene and polypropylene is subjected to a release treatment with a silicone resin release agent, a fluororesin release agent and other organic release agents. Examples of the separator include

[0026]

Embodiments of the present invention will be described below.

(Example 1) A low density polyethylene having a thickness of 5
0 μm, 90 parts by weight of SEBS, 15 parts by weight of tackifier (trade name: Escoletz 5300), additive X [melting point 90
0.5 parts by weight of polyethyleneimine (trade name: RP20, manufactured by Nippon Shokubai Kagaku Co., Ltd.) added with octadecylisocyanate having a molecular weight of 10,000, and additive Y [melting point 14
Two-layer coextrusion molding of a pressure-sensitive adhesive layer containing 3 parts by weight of ethylenebisstearic acid amide having a molecular weight of 592] of 1 part by a T-die method at a mold temperature of 180 ° C. to obtain a surface protection film. Was produced.

(Example 2) A surface protective film was prepared in the same manner as in Example 1 except that the content of the additive X in Example 1 was changed to 2 parts by weight.

(Example 3) The low-density polyethylene forming the outermost layer has a thickness of 40 μm, 100 parts by weight of low-density polyethylene, 1 part by weight of additive X (supra) and Y (supra).
The intermediate layer consisting of 0.2 parts by weight has a thickness of 10 μm and SEB.
90 parts by weight of S (previous), 15 parts by weight of tackifier (previous), 1 part by weight of additive X (previous) and additive Y (previous)
A pressure-sensitive adhesive layer containing 0.5 part by weight was used as the innermost layer having a thickness of 10 μm, and three layers were coextruded by a T-die method at a mold temperature of 180 ° C. to prepare a surface protective film.

Comparative Example 1 A surface protective film was produced in the same manner as in Example 1 except that the additive Y of Example 1 was not used.

Comparative Example 2 A surface protective film was produced in the same manner as in Example 1 except that the additive X of Example 1 was not used.

Comparative Example 3 A surface protective film was prepared in the same manner as in Example 1 except that 1 part by weight of oleic acid amide having a melting point of 73 ° C. and a molecular weight of 298 was used instead of the additive Y in Example 1. did.

Comparative Example 4 A surface protective film was prepared in the same manner as in Example 1 except that the content of the additive X in Example 1 was changed to 10 parts by weight and the content of the additive Y was changed to 5 parts by weight. It was made.

With respect to the surface protective films obtained in the above Examples and Comparative Examples, tests of initial adhesive strength, adhesive strength with time and peel strength with time were measured and evaluated by the following methods. The measurement and evaluation results are shown in Table 1.

1. Initial adhesive strength: Based on JIS Z 0237, a test piece that was stuck on a SUS # 304BA plate with a load of 2 kg / cm and left for 20 minutes was tested for initial adhesive strength at a speed of 300 mm / min using a tensile tester. It was measured.

2. Adhesive strength with time: Based on JIS Z 0237, a test piece prepared in the same manner as in the previous section was aged under heating at 40 ° C for 2 weeks, and then the adhesive strength with time was measured in the same manner as in the previous section.

3. Peeling force with time: For a test piece that was aged in the same manner as in the previous section (Adhesion with time), after cooling to 23 ° C.,
The time-dependent peeling force was measured at the same temperature at a speed of 30 m / min using a high-speed tensile tester.

[0038]

[Table 1]

[0039]

EFFECTS OF THE INVENTION The surface protective film of the present invention, having the above-mentioned constitution, stably maintains the initial adhesive force and the adhesive force with time to the adherend, and peels from the adherend after use. There is no adhesive residue when doing.

Further, since the method for producing a surface protective film of the present invention is constructed as described above, it is easy to increase the bleed-out amount of the additives X and Y to the surface of the adhesive layer in the production process of the surface protective film. In addition to being able to control the surface, the interface of the base material layer and the adhesive layer are intruded into each other and firmly laminated, so that the above-mentioned initial adhesive strength and adhesive strength with time are stably maintained. The film can be easily manufactured.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location C09J 7/02 JKK C09J 7/02 JKK JKZ JKZ B29C 47/06 9349-4F B29C 47/06 47/88 9349- 4F 47/88 B32B 27/00 B32B 27/00 Z 27/18 27/18 27/30 102 27/30 102 // B29K 23:00 B29L 7:00 9:00

Claims (3)

[Claims] 1. A block copolymer having the general formula ABA on one surface of a base material layer made of a polyolefin resin film (where A is a styrene polymer block, and B is a block).
Is a butadiene polymer block, an isoprene polymer block or an olefin polymer block obtained by hydrogenating these) as a main component, and a surface protective film provided with an adhesive layer containing a tackifier. The base material layer and / or the pressure-sensitive adhesive layer contain the following two kinds of additives X and Y, and the additive X has a melting point of 60 to 100.
Polyethyleneimine and / or polyvinyl alcohol having a higher alkyl group having a molecular weight of 8000 to 100,000 and having a melting point of 120 to 120.
180 ° C, 14 to 14 carbon atoms with a molecular weight of 1000 or less
23 is a fatty acid amide and is a total amount per surface area of the base material layer and / or the adhesive layer, and the additive X20 to
400 mg / m ² and additive Y10-300 mg / m ²
A surface protective film comprising: 2. The method for producing a surface protective film according to claim 1, wherein the base material layer made of a polyolefin resin film and the adhesive layer are integrally laminated by multilayer extrusion molding to form a film. 3. When a base material layer made of a polyolefin resin film and an adhesive layer are integrally laminated by multi-layer extrusion molding to form a film, the film extruded from a multi-layer extrusion molding die is extruded within 2 seconds. It cools to 60 degrees C or less, The manufacturing method of the surface protection film of Claim 1 or Claim 2 characterized by the above-mentioned.