JPH08157681A - Surface protecting film - Google Patents

Abstract

PURPOSE: To prepare a surface protecting film, having a stable adhesive strength with time as a masking material for protecting the surface of a synthetic resin sheet without causing the breakage or sticking of the film even when processing is carried out while applying the film in processing such as printing and hot molding. CONSTITUTION: This surface protecting film comprises (A) an acrylic resin and (B) a thermoplastic resin composition containing a block copolymer, composed of >=2 blocks, comprising an aromatic vinyl monomer and having 3000-40000 number-average molecular weight in the molecule and >=1 blocks comprising isoprene or isoprene-butadiene 50% of which is hydrogenated and having 20000-100000 number-average molecular weight, at a weight ratio within the range of (30/70) to (70/30) weight ratio (A)/(B).

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 protective film suitable for a synthetic resin sheet which can be thermoformed with the surface protective film attached.

[0002]

2. Description of the Related Art Plates such as metal plates, coated steel plates, glass plates, resin plates, etc., especially acrylic resin sheets, polycarbonate resin sheets, vinyl chloride resin sheets, etc. are synthesized. The surface of the resin sheet is easily damaged during storage and distribution, and a surface protective film is used to prevent this, and various types have been proposed in the past. The most commonly used in recent years is a laminated film obtained by coextruding an ethylene / vinyl acetate copolymer and polyethylene, and the ethylene / vinyl acetate copolymer layer serves as an adhesive layer. It adheres to the surface of the synthetic resin sheet. The surface protection film is used for sheet transportation, machining,
It is required that the sheet is sufficiently adhered to the sheet so that it does not peel off during handling such as thermoforming, and that it can be easily peeled off when it becomes unnecessary at the final stage of processing. Therefore, the adhesive strength of the surface protective film is 180 ° peeling test (pulling speed 300 mm / mi
The peeling force in n) is usually in the range of about 3 to 350 g / 25 mm width.

However, the adhesive strength of the adhered surface protective film often increases with time, and this tendency is accelerated as the storage temperature is higher, so that the surface protective film has an appropriate adhesive strength at the initial stage. However, the adhesive strength increases considerably due to the change over time, and it becomes impossible to easily peel it off. Therefore, there is a problem that workability is deteriorated at the final stage of processing. Further, when the resin sheet is heated while the surface protective film is attached in the processing step, there is a problem that the above-mentioned problems become more remarkable. For example, in the case of an acrylic resin sheet that is processed on the front plate of a vending machine, the surface protective film is pasted at a resin temperature of about 30 ° C. after extrusion molding, but when printed, generally only the printing surface is printed. The surface is peeled off and the back side is covered with a surface protective film to prevent scratches.
To be heated. Further, when printing becomes multicolor printing, heat drying is repeatedly heated by the number of colors, so the adhesive layer made of ethylene / vinyl acetate copolymer is repeatedly subjected to a high temperature heat history, so that the surface protective film The adhesive strength of is increased, and peeling is often difficult. Further, when vacuum molding is performed with the surface protective film attached to the surface of the resin sheet, the adhesive force of the surface protective film is further increased because the surface protective film is heated to about 160 ° C., and peeling work becomes difficult. Alternatively, there is a problem that the surface protection film melts and a part of the surface protection film remains in the molded product.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a masking material for protecting the surface of a synthetic resin sheet or the like, which has a stable adhesive force with time and is applied during processing such as printing and thermoforming. It is to provide a surface protection film which is free from film breakage or adhesion even if it is processed as it is.

[0005]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that a film made of a resin composition of an acrylic resin and a specific thermoplastic elastomer is on the surface. The present invention has been completed by finding that it is suitable as a protective film. That is, the gist of the present invention lies in (A) acrylic resin, and (B)
Number average molecular weight of two or more in the molecule is 3000 to 4000
A block consisting of 0 aromatic vinyl monomers and one or more isoprene or isoprene-butadiene 5
Thermoplastic containing a block copolymer composed of 0% or more hydrogenated blocks and having a number average molecular weight of 20,000 to 100,000 in a weight ratio (A) / (B) = 30/70 to 70/30 A surface protection film made of a resin composition and 100 parts by weight of the total amount of the acrylic resin and the block copolymer were further mixed with 3 parts by weight of an olefin resin.
To 250 parts by weight, and a surface protection film in which these films are provided on one side of a polyolefin film.

The present invention will be described in detail below. The acrylic resin (A) used in the present invention means a homopolymer of methyl methacrylate or a copolymer of a monomer mixture containing methyl methacrylate as a main component and other copolymerizable monomers, Those having a degree of 3000 or less are preferably used. When further transparency is required, the degree of polymerization is 3
About 100 to 1000 is preferable, and the degree of polymerization is 400 to 400.
At 600, the melt flow rate is 25-34g / 10mi
It is more preferable that n (200 ° C.-3.8 Kg).

Examples of the monomer copolymerizable with methyl methacrylate include methyl acrylate, ethyl acrylate,
Acrylic esters such as butyl acrylate and 2-ethylhexyl acrylate, ethyl methacrylate, butyl methacrylate, 2-hydroxyethyl methacrylate, methacrylic acid esters such as glycidyl methacrylate and cyclohexyl methacrylate, acetic acid such as vinyl acetate Aromatic vinyl compounds such as esters, styrene and α-methylstyrene, maleic anhydride, maleic acid mono- and dialkyl esters, maleimides such as N-phenylmaleimide, acrylic acid, methacrylic acid, acrylic acid metal salts and methacrylic acid. Examples thereof include metal salts. One or more of these may be used, but the copolymerization ratio with methyl methacrylate is preferably used in the range of usually about 1 to 30% by weight.

The block copolymer (B) used in the present invention has two or more number average molecular weights of 3,000 to 40 in the molecule.
000, preferably 3000 to 15000, consisting of aromatic vinyl monomers and one or more isoprene or isoprene-butadiene blocks containing 50% or more, preferably 85 to 100%, and having a number average molecular weight. Is a copolymer of 20,000 to 100,000, preferably 30,000 to 70,000, and is used as a thermoplastic elastomer.

Examples of the aromatic vinyl monomer as the first component of the block copolymer include anionically polymerizable styrene, 2-vinylnaphthalene, 3-methylstyrene, 4
-Propyl styrene and the like can be mentioned, and styrene is most preferably used. Further, the monomer of the second component of the block copolymer is isoprene or a mixture of isoprene and butadiene, and the ratio of isoprene is preferably in the range of 40 to 100% by weight in terms of tackiness. As a block form of the block copolymer composed of these components, when a block composed of an aromatic vinyl monomer is represented by a, a block composed of isoprene or isoprene-butadiene is represented by b, and an integer of 1 or more is represented by a ( The number average molecular weight of the a block is 3000 to 15000, and the content of the a block in the block copolymer is 15 to 3 represented by ba) n and (ab) n.
5% by weight, the weight ratio of isoprene and butadiene constituting the b block is in the range of 40/60 to 100/0, and the number average molecular weight of the block copolymer is 30,000 to 70.
Those satisfying 000 are most preferable in terms of transparency and tackiness.

The above block copolymer can be obtained by various methods, for example, using an alkyl lithium compound as an initiator, an aromatic vinyl monomer, isoprene or isoprene-.
A method of sequentially polymerizing butadiene, or a method of polymerizing an aromatic vinyl monomer, isoprene or isoprene-butadiene and coupling with a coupling agent, or an aromatic vinyl monomer, isoprene or a dilithium compound as an initiator. Examples include a method of sequentially polymerizing isoprene-butadiene. As one of preferred embodiments, a method for obtaining a polymer by anionic living polymerization using an organic alkali metal catalyst and then hydrogenating the polymer to obtain a ternary block copolymer will be specifically described below. For example, a saturated aliphatic hydrocarbon compound such as hexane and heptane using an anionic polymerization initiator such as n-butyllithium, or an aromatic hydrocarbon compound such as benzene and toluene is used as a solvent, and a temperature condition of 30 to 60 ° C. Below, a living polymer is produced by anionically polymerizing an aromatic vinyl monomer, and then a conjugated diene-based monomer such as isoprene or isoprene-butadiene mixture is dropped into the system to perform block copolymerization. Then, the aromatic vinyl monomer is dropped again into the system to produce a block copolymer.

When carrying out the polymerization, ethers such as dimethyl ether, diethyl ether, tetrahydrofuran and dioxane, glycol ethers such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether are used as cocatalysts. , Triethylamine, N, N,
A Lewis base such as amines such as N ′, N′-tetramethylethylenediamine, N-methylmorpholine and the like was added to the O.V. 1-100
When it is used in the range of 0 times, the microstructure of the block segment composed of isoprene and / or butadiene is changed to contain a vinyl bond. When this vinyl structural unit is 40% or more, it has a room temperature glass transition temperature, and it is possible to impart vibration damping performance near room temperature (JP-A-2-102212).

When the block copolymer reaches a desired molecular weight, an active hydrogen compound such as alcohols, carboxylic acids and water is added to terminate the polymerization. Then, the obtained copolymer is hydrogenated. A homogeneous catalyst or a heterogeneous catalyst can be used as the hydrogenation catalyst. When using a homogeneous catalyst, an organic transition metal catalyst (for example, nickel acetylacetonate, cobalt acetylacetonate, nickel naphthenate, cobalt naphthenate, etc.)
And a Ziegler catalyst in combination with a metal alkylated product of aluminum, an alkali metal, an alkaline earth metal, etc., in an amount of 0.01 per double bond of the polymer subjected to hydrogenation.
Use about 0.1 mol%. Hydrogenation reaction is from room temperature to 15
It is carried out at 0 ° C. under a hydrogen pressure of atmospheric pressure to 50 kg / cm ² and is completed in about 1 to 50 hours. After completion of the reaction, acidic water is added to the vessel and vigorously stirred to dissolve the hydrogenation catalyst in water. The target block copolymer is obtained by removing the aqueous phase of the two phases that have been phase-separated and further removing the solvent. On the other hand, when a heterogeneous catalyst is used, nickel, cobalt, palladium, rhodium, ruthenium, platinum or the like is used alone or these are supported on silica, diatomaceous earth, alumina, activated carbon or the like, and the amount thereof depends on the polymer weight. On the other hand, 0.5 to 10% by weight is suitable. This is added to the polymerization reaction liquid. At this time, ethers such as diethyl ether, tetrahydrofuran and dioxane, and alcohols such as ethanol and isopropanol can also be used as a mixed solvent. Hydrogenation reaction is from room temperature to 250
It is carried out at a temperature of 0 ° C. under a hydrogen pressure of 200 kg / cm ^{2 to} atmospheric pressure, and is completed in about 1 hour to 50 hours. After completion of the reaction, the reaction product is taken out of the container, and the solvent is removed from the filtrate of the catalyst to obtain the target block copolymer.

The surface protective film of the present invention has the above-mentioned (A).
Thermoplastic resin containing acrylic resin and (B) block copolymer in a weight ratio (A) / (B) of 30/70 to 70/30, preferably 40/60 to 60/40 The thermoplastic resin composition may further contain an olefin resin. As the olefin resin, low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-α olefin copolymer, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene -Butyl acrylate copolymer, ethylene-methyl methacrylate copolymer, polypropylene and the like can be mentioned, and these can be used alone or as a blend of two or more kinds. The compounding amount of the olefin resin is 10 (A) of the acrylic resin and (B) the total amount of the block copolymer.
3 to 250 parts by weight is preferable with respect to 0 parts by weight, and when considering the adhesive force with the resin sheet and the molding stability of the film, it is 1
The range of 0 to 150 parts by weight, more preferably 15 to 100 parts by weight is desirable. Further, the thermoplastic resin composition, to the extent that the performance as a surface protective film is not impaired, an ultraviolet absorber, an antioxidant, an antioxidant, a filler, an antiblocking agent, a lubricant, an antistatic agent, a plasticizer, an adhesive. It is also possible to add an imparting agent and the like. As the tackifier, for example, terpene resin, chroman-indene resin, rosin resin and the like can be preferably used.

The form of the surface protective film is a thermoplastic resin composition comprising the above-mentioned (A) acrylic resin and (B) block copolymer, and the above-mentioned (A) acrylic resin and (B) block copolymer. And (C) a one-layer structure film or a two-layer structure film made of a thermoplastic resin composition comprising an olefin resin, or a film in which a film made of the thermoplastic resin composition is provided on one side of the olefin resin film. Is mentioned. The thickness of the surface protective film is usually 30 to 30 for both single layer and multiple layers.
It is about 0 μm, and is 40 to 100 μm in terms of cost and the like.
The thing of a grade is used preferably.

The method for producing the surface protective film of the present invention is not particularly limited, and examples thereof include a method for producing an ordinary film such as a T-die extrusion method, an inflation method and a calendar roll method. Single layer by these methods,
Although a multi-layer film can be produced, the T-die extrusion method is preferably adopted among these methods because it can be coextruded and has excellent thickness accuracy.

The surface protective film of the present invention can be used for protecting the surface of various plate-shaped bodies such as metal plates, coated steel plates having various resin coating surfaces such as polyester, glass plates, resin plates and the like. Acrylic resin sheet, polycarbonate resin sheet, vinyl chloride resin sheet, styrene type resin sheet, which requires processing such as thermoforming with the surface protective film attached. It is preferably used as a surface protective film for synthetic resin sheets such as resin sheets.

[0017]

EXAMPLES The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples. The tests and evaluations were carried out by the following methods.

<Peeling Force Measurement Test> A sample (size: 25 mmW × 200 mmL ×) adjusted under the following storage conditions using an autograph (manufactured by Shimadzu Corporation: AG2000B)
About the plate thickness), a film with a width of 25 mm has a speed of 300 m.
Pull at m / min and measure 180 ° peel force. (Storage conditions) Store at room temperature (23 ° C) for 24 hours Store at 120 ° C for 1 hour Store at 160 ° C for 5 minutes Store at 180 ° C for 5 minutes

<Evaluation of Pen-Plate Moldability> A vacuum pressure compression molding machine (made by Fuse Vacuum Co., Ltd .: CUCF-1115-PWB150),
Epoxy resin pen mold (dimension: 100mmW x 3
10 mmL × 20 mmH) and an infrared heater (Elstein heater), and the upper heater temperature is 400.
C., the lower heater temperature is set to 360.degree. C., the sample (dimensions: 320 mmW.times.480 mmL.times.plate thickness) is heated from both sides of the sample until the surface temperature reaches 155.degree. It was placed on the above and vacuum-molded by a molding machine. The moldability and mold adhesion of the obtained pen dish molded product were evaluated, and the releasability of the surface protective film from the molded product was visually and sensory-evaluated and shown by the following symbols. (Moldability) ○: The surface protective film is not broken and the moldability is good. ×: The surface protective film is broken (die adhesion) ○: The surface protective film is not attached to the molding die ×: The surface protective film is not attached to the molding die. There is some adhesion (Peelability) ○: Good peelability of the surface protection film ×: Poor peelability of the surface protection film

<Evaluation of Stretchability> The sample was heated to 160 ° C. and stretched about 3 times by using a molding machine and a heater similar to those used for the evaluation of moldability of a pen plate. Sensory evaluation was performed. The results are shown by the following symbols. ○: Good peelability of the surface protection film ×: Poor peelability of the surface protection film

[Example 1] (A-1): Acrylic resin [Polymerization degree 495, MFR3
0.8 g / 10 min (200 ° C.-3.8 Kg)],
(B-1): Styrene-hydrogenated isoprene (hydrogenation rate 97%)-styrene block in which the number average molecular weight of the block made of styrene is 5300, the content of styrene is 30% by weight, and the number average molecular weight of the block copolymer is 40,000. A thermoplastic resin composition prepared by blending the copolymer in a weight ratio of (A-1) / (B-1) = 50/50 was formed into a film having a thickness of about 200 μm by an inflation method. The surface protection film was transparent and had a good appearance. This film has a resin plate temperature of about 70 ° C immediately after extrusion molding.
When the temperature has dropped to, the resin plate has a dry laminator.
And a methacrylic resin extruded plate having a thickness of 3 mm [manufactured by Kuraray Co., Ltd .: Comograss] was obtained. A sample was taken from the obtained extruded plate, a peel strength measurement test was performed, and a pen plate formability evaluation and a stretchability evaluation were performed to evaluate the heat formability. The results are shown in Tables 1 and 2. The peeling force was good because the peeling force was within the range of the adhesive force for easy peeling under each storage condition, and the heat moldability was also good.

Example 2 Same as Example 1 except that 100 parts by weight of the same thermoplastic resin composition as in Example 1 was further mixed with 10 parts by weight of polyethylene (LLDPE2022L manufactured by Mitsui Petrochemical Co., Ltd.). Then, a film and an extruded plate were produced, and the same tests and evaluations as in Example 1 were performed. The obtained results are shown in Tables 1 and 2. The peeling force was good because the peeling force was within the range of the adhesive force for easy peeling under each storage condition, and the heat moldability was also good.

Example 3 100 parts by weight of the same thermoplastic resin composition as in Example 1 and 17 parts by weight of the polyethylene used in Example 2 were blended in the same manner as in Example 1. A film and an extruded plate were produced, and the same tests and evaluations as in Example 1 were performed. The obtained results are shown in Tables 1 and 2. The peeling force was good because the peeling force was within the range of the adhesive force for easy peeling under each storage condition, and the heat moldability was also good.

Example 4 Similar to Example 1 except that 100 parts by weight of the same thermoplastic resin composition as in Example 1 and 100 parts by weight of the polyethylene used in Example 2 were blended. A film and an extruded plate were produced, and the same tests and evaluations as in Example 1 were performed. Table 1 shows the obtained results.
And shown in Table 2. The peeling force was good because the peeling force was within the range of the adhesive force for easy peeling under each storage condition, and the heat moldability was also good.

[Example 5] 100 parts by weight of the same thermoplastic resin composition as in Example 1 and 100 parts by weight of polypropylene (RE398 manufactured by Ube Industries) were added, and the same thermoplastic resin as in Example 1. Films were produced in the same manner as in Example 1 except that 100 parts by weight of the composition and 10 parts by weight of the same polyethylene as in Example 2 were used, and these two films were heated at 230 ° C. with a tabletop press.
A surface protective film was manufactured by pressing and pasting.
Thereafter, an extruded plate was produced in the same manner as in Example 1, and Example 1
The same test / evaluation was performed. The obtained results are shown in Tables 1 and 2. The peeling force was good because the peeling force was within the range of the adhesive force for easy peeling under each storage condition, and the heat moldability was also good.

[Example 6] 100 parts by weight of the same thermoplastic resin composition as in Example 1 was further mixed with 100 parts by weight of polypropylene (RE398 manufactured by Ube Industries), and the same thermoplastic resin as in Example 1 Films were produced in the same manner as in Example 1 except that 100 parts by weight of the composition and 17 parts by weight of the same polyethylene as in Example 2 were blended, and these two films were heated at 230 ° C. on a tabletop press.
A surface protective film was manufactured by pressing and pasting.
Thereafter, an extruded plate was produced in the same manner as in Example 1, and Example 1
The same test / evaluation was performed. The obtained results are shown in Tables 1 and 2. The peeling force was good because the peeling force was within the range of the adhesive force for easy peeling under each storage condition, and the heat moldability was also good.

Example 7 The same as Example 1 except that 100 parts by weight of the same thermoplastic resin composition as in Example 1 was further mixed with 10 parts by weight of the polypropylene used in Example 5. A film and an extruded plate were produced, and the same tests and evaluations as in Example 1 were performed. Table 1 shows the obtained results.
And shown in Table 2. The peeling force was good because the peeling force was within the range of the adhesive force for easy peeling under each storage condition, and the heat moldability was also good.

Example 8 The same as Example 1 except that 100 parts by weight of the same thermoplastic resin composition as in Example 1 was mixed with 43 parts by weight of the polypropylene used in Example 5. A film and an extruded plate were produced, and the same tests and evaluations as in Example 1 were performed. Table 1 shows the obtained results.
And shown in Table 2. The peeling force was good because the peeling force was within the range of the adhesive force for easy peeling under each storage condition, and the heat moldability was also good.

Example 9 (A-2): Acrylic resin (Kuraray Parapet G1000) and (B-2): Styrene block number average molecular weight 8000, styrene content 30% by weight, block co-weight Styrene-hydrogenated isoprene (hydrogenation rate 9
7%)-styrene block copolymer in a weight ratio (A-
2) / (B-2) = 50/50 In the same manner as in Example 1 except that 100 parts by weight of the thermoplastic resin composition was further mixed with 43 parts by weight of the same polypropylene as in Example 5. To produce a film and an extruded plate, and the same tests and evaluations as in Example 1 were performed. The obtained results are shown in Tables 1 and 2. The peeling force was good because the peeling force was within the range of the adhesive force for easy peeling under each storage condition, and the heat moldability was also good.

[Example 10] 100 parts by weight of the same thermoplastic resin composition as in Example 1 was further mixed with 10 parts by weight of the polyethylene used in Example 2, and the polypropylene used in Example 5 was used. In the same manner as in Example 1,
Films were produced respectively, and these two types of films were pressed at 230 ° C. with a tabletop press machine and laminated to produce a surface protection film. Then, an extruded plate was manufactured in the same manner as in Example 1, and the same tests and evaluations as in Example 1 were performed.
The obtained results are shown in Tables 1 and 2. Peeling force is good because it is within the range of adhesive force for easy peeling under each storage condition.
The heat moldability was also good.

[Example 11] 100 parts by weight of the same thermoplastic resin composition as in Example 1 was further mixed with 17 parts by weight of the polyethylene used in Example 2, and polypropylene used in Example 5 was used. In the same manner as in Example 1,
Films were produced respectively, and these two types of films were pressed at 230 ° C. with a tabletop press machine and laminated to produce a surface protection film. Then, an extruded plate was manufactured in the same manner as in Example 1, and the same tests and evaluations as in Example 1 were performed.
The obtained results are shown in Tables 1 and 2. Peeling force is good because it is within the range of adhesive force for easy peeling under each storage condition.
The heat moldability was also good.

[Embodiment 12] Similar to Embodiment 1 (A-
1): Acrylic resin and (B-3): number-average molecular weight of block consisting of styrene 5300, styrene content 30
% By weight, number average molecular weight of block copolymer is 40,000
Of styrene-hydrogenated isoprene / butadiene (isoprene / butadiene = 55/45% by weight, hydrogenation rate 98%)-styrene block copolymer in a weight ratio (A-1) / (B-
3) = 50/50 A thermoplastic resin composition blended was used to produce a film and an extruded plate in the same manner as in Example 1, and the same tests and evaluations as in Example 1 were performed. The obtained results are shown in Tables 1 and 2. The peeling force was good because the peeling force was within the range of the adhesive force for easy peeling under each storage condition, and the heat moldability was also good.

[Example 13] 100 parts by weight of the same thermoplastic resin composition as in Example 1 and 100 parts by weight of the polyethylene used in Example 2 were blended with 100 parts by weight of the same thermoplastic resin composition as in Example 1. A mixture of 25 parts by weight of the polyethylene used in Example 2 in parts by weight was used to prepare a surface protection film having a two-layer structure having a thickness of 70 μm by an inflation coextrusion method. The surface protection film was transparent and had a good appearance. This film was laminated in the same manner as in Example 1 with 100 parts by weight of the thermoplastic resin composition containing 25 parts by weight of polyethylene on the side of the extruded plate as in Example 1, and the same tests and evaluations as in Example 1 were performed. I went. The obtained results are shown in Tables 1 and 2. The peeling force was good because the peeling force was within the range of the adhesive force for easy peeling under each storage condition, and the heat moldability was also good.

[Comparative Example 1] Polyethylene masking manufactured by San-E Kagaku Co. (structure is composed of ethylene / vinyl acetate copolymer and polyethylene: trade name PAC-5, thickness 60)
The surface protective film of μ) was attached in the same manner as in Example 1, and the same tests and evaluations as in Example 1 were performed. The obtained results are shown in Tables 1 and 2. The peeling force was increased by heating and was not easily peeled off. Further, regarding the heat moldability, breakage occurred in the contact portion between the surface protective film and the molding die, and the surface protective film partially adhered to the mold.

[0035]

[Table 1]

[Comparative Example 2] Polyethylene masking manufactured by San-E Chemical (The structure is a two-layer structure of polyethylene,
A tackifier is added to the adhesive layer side: trade name PA
A surface protective film of C-4H, thickness 60 μ) was used in Example 1.
The pieces were laminated in the same manner as in Example 1 and tested for formability and stretchability in the case of Example 1. The obtained results are shown in Table 2. As for moldability, a part of the surface protective film that was in contact with the mold broke, and part of the film was attached to the mold. Further, the stretchability was good, showing the same elongation without restricting the elongation of the material, and the material could be easily peeled off.

[0037]

[Table 2]

[0038]

EFFECTS OF THE INVENTION According to the present invention, the adhesive has a proper initial adhesive force, shows little change with time in the adhesive force even when placed under heating, and is easily peeled off. It is possible to provide a surface protection film that does not adhere to a mold.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location C08L 23/00 LCK LCN 53/02 LLY (72) Inventor Atsushi Atsushi Miyukigaoka, Tsukuba, Ibaraki 41 Kuraray Co., Ltd.

Claims (4)

[Claims] 1. An acrylic resin of (A) and a number average molecular weight of two or more in the molecule (B) of 3,000 to 40,000.
And a block composed of one or more isoprene or isoprene-butadiene.
Thermoplastic resin containing a block copolymer having a number average molecular weight of 20,000 to 100,000 and composed of hydrogenated blocks in an amount of (A) / (B) = 30/70 to 70/30. A surface protective film comprising the composition. 2. The surface protective film according to claim 1, further comprising 3 to 250 parts by weight of an olefin resin, based on 100 parts by weight of the total amount of the acrylic resin and the block copolymer. 3. The surface protective film according to claim 1, which has a two-layer structure. 4. A surface protective film comprising a polyolefin film provided with the film according to claim 1 or 2 on one side thereof.