JP2009057469A - Surface protective film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface protective film excellent in initial adhesion strength and stability of the adhesion strength with time, hardly peeled from the adherend by wind pressure, easily peeled from the adherend upon peeling, and hardly leaving an adhesive residue or adhesion trace on the adherend. <P>SOLUTION: The surface protective film has an adhesive layer 3 containing a rubber resin component and a tackifying resin layered on a polyolefin substrate 2. The rubber resin component comprises a styrene elastomer essentially comprising a block copolymer of styrene polymer blocks (A) and isobutylene polymer blocks (B), block copolymer of styrene polymer blocks (A) and random copolymer blocks (B') of styrene and isobutylene, and/or their hydrolyzed polymers. The adhesion imparting resin contains paraffin oil. The adhesion layer contains 5 to 40 parts by weight of paraffin oil with respect to 100 parts by weight of the rubber resin component. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a surface protective film for preventing adhesion of dust to the surface of an adherend and scratching of the surface of the adherend, and in particular, a surface on which a rubber-based adhesive layer is laminated on one side of a polyolefin-based substrate. It relates to a protective film.

  In order to protect various articles and members, a surface protective film is often temporarily attached to the surfaces of the articles and members. For example, various adherends such as synthetic resin plates, metal plates, decorative plywood, painted steel plates, painted resin plates, or various nameplates, especially the surfaces of coated steel plates and painted resin plates, during processing and transportation to these surfaces In order to prevent the adhesion of dirt and scratches on the surface, surface protection films are frequently used.

  This type of surface protective film has a structure in which an adhesive layer is laminated on one side of a film substrate. In general, a film substrate made of a thermoplastic resin is used as the film substrate. The surface protective film is affixed to the adherend surface using the adhesive force of the pressure-sensitive adhesive layer to protect the adherend surface. When the adherend is used, the surface protective film is peeled off from the adherend surface. Therefore, the surface protective film is required to have appropriate adhesiveness so that it can be easily temporarily attached to the surface of the adherend, and can be easily peeled off from the adherend surface after use. It is required to have a good releasability. Further, there is a strong demand for no adhesive residue or adhesion marks on the adherend surface after peeling.

  For example, automobile bodies and parts that have been painted may be loaded onto trucks or ships and transferred to remote locations such as overseas. During transfer, various suspended matters such as dust, dust, and rain adhered to the coating film, and the coating film was sometimes stained or discolored. Moreover, the coating film may be damaged by the collision object.

  Therefore, in order to prevent such contamination, discoloration, damage and the like of the coating film, a surface protective film is temporarily attached to the coating film surface and transferred to remote places such as overseas.

  This type of surface protective film for protecting a coating film also has a structure in which an adhesive layer is laminated on one side of a film substrate. In general, a film made of a thermoplastic resin is used as the film substrate.

  Surface protective films used for the surface protection of coating films such as the above-mentioned coated steel sheets and surface protective films for protecting various articles are generally temporarily attached to the surface to be protected by hand attachment and peeled off prior to use. The

  Therefore, the surface protective film has 1) sufficient initial adhesive strength, 2) good stability of adhesive strength with time, 3) difficult to peel off from the adherend due to wind pressure, and 4) deposition during peeling. It is required that it can be easily peeled off from the body, 5) it is difficult for adhesive residue to form on the adherend after peeling, and 6) it is difficult to form adhesion marks.

  Patent Document 1 below discloses a surface protective film for protecting an automobile coating film in which a pressure-sensitive adhesive layer is laminated on the surface of a substrate, and polyisobutylene is used as the pressure-sensitive adhesive layer. Here, it is shown that the performance of the surface protective film can be improved by using polyisobutylene for the pressure-sensitive adhesive layer. However, although the polyisobutylene-based pressure-sensitive adhesive is excellent in adhesive strength over time and peeling workability, it has a relatively low cohesive force. Therefore, when the surface protective film was peeled off from the coated steel plate after the heat resistance and humidity resistance tests, adhesive residue was likely to occur. That is, there was room for improvement with respect to the adhesive residue of 5) above.

  On the other hand, the following Patent Document 2 discloses a surface protective film using an adhesive layer made of a styrene elastomer. Here, by controlling the elastic modulus of the pressure-sensitive adhesive layer, it is said that 1) the initial adhesive force is in a sufficient range, and 2) the temporal stability of the adhesive force is enhanced. However, 4) the peeling workability was inferior to the surface protective film using polyisobutylene for the pressure-sensitive adhesive layer.

  In addition, conjugated dienes are used for the elastomer part of the soft segment, and hydrogenation is finally performed. However, industrially, it is difficult to completely add hydrogen to 100%, so heat resistance is sufficient. It wasn't.

  On the other hand, in the following Patent Document 3, a pressure-sensitive adhesive layer is laminated on the surface of a base material, and the pressure-sensitive adhesive layer comprises 100 parts by weight of a styrene-isobutylene block copolymer, and a softening agent of 300 parts by weight or less, A surface protective sheet containing 0 to 20 parts by weight of a tackifying resin is disclosed. In Patent Document 3, due to this configuration, the adhesive force is stable even when exposed to a high temperature of 70 ° C., compared to the case of a natural rubber-based pressure-sensitive adhesive layer or other pressure-sensitive adhesive layers of styrene elastomer, It is said to be excellent in extrudability.

However, in Patent Document 3, although many materials are described as the softening agent and the tackifying resin, depending on the type of the tackifying resin used, the surface protective film was peeled off from the coated steel plate after the heat and humidity resistance tests. Occasionally, adhesion marks and adhesive residue may be remarkably formed on the adherend at the edge of the surface protective film or at places where the surface protective film is wrinkled at the time of application.
JP-A-6-73352 JP 2001-234149 A Japanese Patent No. 3887402

  The object of the present invention is to eliminate the above-mentioned disadvantages of the prior art, and is excellent in initial adhesive force and stability over time of the adhesive force, difficult to peel off from the adherend due to wind pressure, and easily peeled off from the adherend during peeling. Another object of the present invention is to provide a surface protective film that is less likely to have adhesive residue on an adherend after peeling and hardly forms adhesion marks.

According to the present invention, there is provided a surface protective film in which an adhesive layer containing a rubber-based resin component and a tackifying resin is laminated on a polyolefin-based substrate, wherein the rubber-based resin component is a styrene polymer block (A ) And an isobutylene polymer block (B), a block copolymer of a styrene polymer block (A) and a random copolymer block (B ′) of styrene and isobutylene, and / or These hydrogenated products are styrene elastomers having a main skeleton, the tackifying resin contains a paraffin oil, and the adhesive layer contains the paraffin oil with respect to 100 parts by weight of the rubber resin component. contained in the range of 5 to 40 parts by weight, the shear storage modulus at a frequency of 10Hz the adhesive layer has a 4 × ¹⁰ 6 Pa or less at -30 ° C., and 70 ° C. Characterized in that at 2 × 10 5 ^Pa or more, the surface protective film is provided.

  On the specific situation with the surface protection film which concerns on this invention, the olefin oligomer is further contained in the said adhesion layer. More preferably, the olefin-based oligomer is contained in the adhesive layer at a ratio of 10 parts by weight or less with respect to 100 parts by weight of the rubber-based resin component.

  In another specific aspect of the surface protective film of the present invention, a surface protective film suitably used as the above-mentioned surface protective film, in particular, as a coating film protecting sheet is provided, and the polyolefin-based substrate contains a weathering agent, And the ultraviolet-ray transmittance in the wavelength range of 190-370 nm of the said polyolefin-type base material shall be 10% or less. In this case, when the surface protection film for protecting the coating film is temporarily attached to a coating film of an automobile or the like and transferred, the temperature of the surface protection film is increased even when the surface protection film is exposed to sunlight or the like. Since the amount of ultraviolet rays that are suppressed and pass through the polyolefin base material and reach the adhesive layer is reduced, the polyolefin base material and the adhesive layer are unlikely to deteriorate. Therefore, when the surface protective film is peeled from the coating film, adhesive residue is less likely to occur on the coating film surface. Furthermore, since the amount of ultraviolet rays passing through the surface protective film and reaching the coating film is also reduced, it is possible to suppress deterioration of the coating film due to ultraviolet rays.

  Details of the present invention will be described below.

  As a result of intensive investigations on a surface protective film in which an adhesive layer is laminated on the surface of a polyolefin-based substrate, the present inventors have found that a styrene-based polymer block (A) and an isobutylene-based polymer block (B ), A block copolymer of a styrenic polymer block (A) and a random copolymer block (B ′) of styrene and isobutylene, and / or a hydrogenated product thereof as a main skeleton. If the paraffinic oil as the tackifying resin is contained in the range of 5 to 40 parts by weight with respect to 100 parts by weight of the rubber-based resin component in the pressure-sensitive adhesive layer using the styrene-based elastomer Has been found to achieve the present invention.

(Rubber resin component)
The pressure-sensitive adhesive layer of the surface protective film according to the present invention contains a rubber-based resin component.

  As described above, the rubber-based resin component is composed of a block copolymer of a styrene-based polymer block (A) and an isobutylene-based polymer block (B), and a styrene-based polymer block (A), styrene- and isobutylene. It is a block copolymer with a random copolymer block (B ′). In other words, the styrene-based elastomers (1) and (2) below.

(1) A styrene elastomer having a main skeleton of a block copolymer of a styrene polymer block (A) and an isobutylene polymer block (B). The styrene-based elastomer is not particularly limited as long as the (A)-(B) block copolymer is a main skeleton. For example, AB, ABA, (AB) _n or (A _-B) copolymers thereof represented by like _n X. In addition, n is an integer greater than or equal to 2, and X is a residue by a coupling agent.

  (2) A styrene elastomer having a main copolymer of a block copolymer of a styrene polymer block (A) and a random copolymer block (B ′) of styrene and isobutylene. Examples of such a styrene elastomer include the following (2-1) to (2-4).

(2-1) A combination of block (A) and block (B ′): AB ′ block copolymer (2-2) Including a tapered block (G) in which styrene of styrene and isobutylene gradually increases Things: AB'-G block copolymer (2-3) What contains a styrene-type polymer block (A) instead of the said taper block (G): AB'-A block copolymer (2) -4) (2-1) to (2-3) of repetition or what they are attached in any _{proportions: (a-B ') n} , (a-B') n X, (a-B'- G) _n X, (AB′-A) _n X and the like.

  In addition, n is an integer greater than or equal to 2, and X is a residue by a coupling agent.

  In the styrene elastomer of the above (2), the content ratio of the components of styrene and isobutylene is preferably in the range of 5:95 to 60:40, more preferably 7:93 to 40:60 by weight ratio. It is a range. When the content of styrene is less than 5% by weight, the cohesive force of the adhesive layer is lowered, and there is a possibility that adhesive residue may be generated on the adherend when the surface protective film is peeled off. It may be insufficient and sticking to the adherend may be difficult.

  In the styrene elastomer of the styrene elastomer of the above (2), in the configuration including the taper block (G), the styrene content and the taper block (A) in the block (A) in all monomer configurations constituting the styrene elastomer ( The total styrene content ratio, which is the sum of the styrene content in G), is preferably in the range of 5 to 50% by weight, more preferably in the range of 5 to 40% by weight, and still more preferably in the range of 5 to 25% by weight. . When the total content of styrene in the block (A) and the tapered block (G) is less than 5% by weight in all monomers, the cohesive force of the adhesive layer is reduced, and the adhesive remains on the adherend when the surface protective film is peeled off. If it exceeds 50% by weight, the adhesive strength of the adhesive layer is insufficient, and sticking to the adherend may be difficult. The styrene content ratio in the block (A) in the constitution of all monomers constituting the styrene elastomer is preferably 3% by weight or more, more preferably 3 to 20% by weight.

  The polystyrene-equivalent weight average molecular weight measured by GPC (gel permeation chromatography) of the styrene elastomer is preferably in the range of 30,000 to 400,000, more preferably in the range of 50,000 to 200,000. When the weight average molecular weight is less than 30000, the cohesive force of the adhesive layer is lowered, and thus, adhesive residue may be generated on the adherend when the surface protective film is peeled off. When the weight average molecular weight exceeds 400,000, the adhesive strength is insufficient, and troubles such as an increase in solution viscosity and melt viscosity may occur during the preparation of the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer and the production of the surface protective film.

(Tackifying resin)
The pressure-sensitive adhesive layer of the surface protective film according to the present invention further includes a tackifier resin in addition to the specific rubber-based resin component.

  Moreover, the said adhesion layer contains paraffinic oil as tackifying resin. The paraffinic oil is contained in the adhesive layer in the range of 5 to 40 parts by weight with respect to 100 parts by weight of the rubber-based resin component. When the paraffinic oil is less than 5 parts by weight, the shear storage elastic modulus of the adhesive layer may be too high, and the adhesive force to the adherend may be insufficient. When the amount exceeds 40 parts by weight, the cohesive force of the pressure-sensitive adhesive is insufficient, and it becomes difficult to peel the surface protective film from the adherend, and it is easy to produce adhesive residue after peeling.

  When the surface protective film is peeled off from the coated steel sheet after the heat and humidity resistance test, the inventors of the present invention blended paraffinic oil as the tackifier resin in the adhesive layer at the specific ratio. It has been found that adhesion marks are difficult to be formed at a part or a portion where a surface protective film is wrinkled at the time of application. It is thought that the mechanism of this adhesion mark is due to the migration of the tackifier resin in the surface protective film and the swelling of the coating film due to the absorption of water vapor in the coating film, especially because paraffinic oil is difficult to transfer to the coating film. In addition, it is considered that adhesion marks are less likely to occur.

  In the present invention, a tackifying resin other than the paraffinic oil may be used in addition to the paraffinic oil.

  Examples of the tackifying resin other than the paraffinic oil include terpene resin, naphthenic process oil, aromatic process oil, castor oil, tall oil, natural oil, liquid polyisobutylene resin, polybutene, and the like. Specifically, as the terpene resin, Yashara Chemical Co., Ltd., trade name: Clearon, as the liquid polyisobutylene resin, BASF Corporation, trade name: Glysopearl, as polybutene, manufactured by Idemitsu Kosan Co., Ltd., trade name: Idemitsu Polybutene, etc. Is mentioned. These may be used independently and 2 or more types may be used together.

  The polystyrene-equivalent weight average molecular weight measured by GPC (gel permeation chromatography) of the tackifying resin is preferably in the range of 300 to 5000, more preferably in the range of 300 to 1500. More preferably, it is the range of 300-1000. If the weight average molecular weight is too small, the cohesive force of the pressure-sensitive adhesive layer is reduced, and thus adhesive residue may be generated on the adherend when the surface protective film is peeled off. On the other hand, even if the weight average molecular weight exceeds 5000, the compatibility with the rubber-based resin component is deteriorated, and adhesive residue may be generated on the adherend when the surface protective film is peeled off.

  When the pressure-sensitive adhesive layer contains a tackifying resin other than paraffinic oil, the pressure-sensitive adhesive layer has a total of 5 to 40 tackifying resins other than paraffinic oil and paraffinic oil with respect to 100 parts by weight of the rubber-based resin component. It is preferably contained in the range of parts by weight. More preferably, it is 10-30 weight part. If the amount is less than 5 parts by weight, the shear storage elastic modulus of the adhesive layer may be too high, and the adhesive force to the adherend may be insufficient. When the amount exceeds 40 parts by weight, the cohesive force of the pressure-sensitive adhesive is insufficient, and it becomes difficult to peel the surface protective film from the adherend, and it is easy to produce adhesive residue after peeling.

(Olefin oligomer)
The adhesive layer of the surface protective film according to the present invention preferably further contains an olefin oligomer in addition to the rubber resin component and the tackifier resin.

  When an olefin oligomer is added to the rubber resin component and the tackifier resin, the elastic modulus of the adhesive layer at high temperature (70 ° C.) is improved, and the cohesive force of the adhesive layer is also improved. In addition, the interfacial adhesive force between the polyolefin base material and the pressure-sensitive adhesive layer is improved, and the adhesive residue is more unlikely to occur at the time of peeling at a high temperature.

  Examples of the olefin oligomer include ethylene oligomer and propylene oligomer. The oligomer referred to here is one having a polystyrene-reduced number average molecular weight of about 10,000 or less determined by GPC.

  Examples of the ethylene-based oligomer include ethylene homo-oligomer, ethylene-acrylic acid oligomer, ethylene-vinyl acetate oligomer, ethylene-maleic anhydride oligomer, and the like. Specifically, as the homo-oligomer of ethylene, manufactured by Honeywell, product name: A-C6, 6A, manufactured by Mitsui Chemicals, product name: Excellex, manufactured by Sanyo Chemical Co., Ltd., product name: manufactured by Sun Wax, Clariant Product name: Licocene PE, ethylene-acrylic acid oligomer, manufactured by Honeywell, product name: A-C540, ethylene-vinyl acetate oligomer, manufactured by Honeywell, product name: A-C400, ethylene-maleic anhydride Examples of the oligomer include Honeywell's product name: A-C573A.

  Examples of the propylene oligomer include propylene homo-oligomer, propylene-ethylene oligomer, propylene-maleic anhydride oligomer, and the like. As a propylene homo-oligomer, Sanyo Kasei Co., Ltd., trade name: Viscol, manufactured by Clariant Co., Ltd., trade name: Lycocene PP6102, 6050M, and as a propylene-ethylene oligomer, manufactured by Clariant Co., Ltd., trade name: Lycocene PP4202, 1302, 1502 1602, propylene-maleic anhydride oligomers manufactured by Clariant, trade name: Recommon, and the like.

  The olefin oligomer is preferably contained in the adhesive layer at a ratio of 10 parts by weight or less with respect to 100 parts by weight of the rubber resin component. More preferably, it is the range of 0.1-10 weight part, More preferably, it is the range of 1-6 weight part. When the olefin oligomer is not included, adhesive residue is likely to be generated on the adherend. Even when the olefin oligomer is included, if the olefin oligomer is too small, the effect of adding the olefin oligomer is small, and thus the adherend is small. The adhesive residue is likely to occur. When there are too many olefin-type oligomers, compatibility with a rubber-type resin component will worsen, and the temporal stability of the adhesive force with respect to a to-be-adhered body may worsen.

  Moreover, it is preferable that the olefin oligomer used by this invention is compatible with the rubber-type resin component added. By controlling the compatibility between the olefin oligomer and the rubber resin component, the temporal stability of the adhesive force is increased, and the adhesive residue is hardly generated even after the lapse of time.

  The compatibility between the rubber-based resin component and the olefin-based oligomer can be evaluated by, for example, the following method.

  5 parts by weight of an olefin oligomer is melt blended with 100 parts by weight of a rubber resin component to produce a 1 mm thick press sheet. In accordance with JIS K 7105, a cell having an optical path length of 10 mm is used, and the haze in the press sheet is measured in liquid paraffin. It shall have compatibility when haze is 20% or less, and shall not have compatibility when haze exceeds 20%.

(Other ingredients blended in the adhesive layer)
In the surface protective film according to the present invention, if necessary, a stabilizer such as a light-resistant agent and an antioxidant, an adhesion progress preventing agent, and the like may be added to the pressure-sensitive adhesive layer as long as the adhesive performance is not impaired.

  The light stabilizer is not particularly limited, and examples thereof include ultraviolet absorbers such as salicylic acid, benzophenone, benzotriazole, and cyanoacrylate, and light stabilizers such as hindered amine compounds. The antioxidant is not particularly limited, and examples thereof include phenol-based (monophenol-based, bisphenol-based, polymer-based phenol-based), sulfur-based and phosphorus-based antioxidants.

  Examples of the anti-adhesion progress agent include fatty acid amides, polyethyleneimine long-chain alkyl grafts, soybean oil-modified alkyd resins (for example, Arakawa Chemical Co., Ltd., trade name “Arachid 251”), tall oil-modified alkyd resins (for example, Arakawa Chemical Co., Ltd., trade name “Arachid 6300”, etc.).

(Polyolefin substrate)
The polyolefin constituting the polyolefin-based substrate is not particularly limited, and polyolefins such as polypropylene and polyethylene, polyolefins mixed with olefin-based elastomers, and the like can be used.

  Although the thickness of the said polyolefin-type base material changes with purposes of use, 20-100 micrometers is preferable. If it is 20 μm or less, the protective performance of an adherend such as a coating film may not be sufficiently exhibited, and if it is 100 μm or more, the cost may be high and production may be difficult.

  Moreover, when an adhesion layer contains the said olefinic oligomer, as an olefinic resin used for a polyolefin-type base material, what is compatible with the said olefinic oligomer is preferable. In this case, the interfacial adhesive force between the polyolefin-based substrate and the adhesive layer, that is, the anchoring property of the adhesive layer to the polyolefin-based substrate is further enhanced.

  Combinations of olefin resins and olefin oligomers with excellent compatibility include propylene polymers (homopolymers, block copolymers, random copolymers) and propylene oligomers, propylene polymers (block copolymers, random copolymers) and ethylene oligomers. And ethylene polymers and ethylene oligomers.

  In particular, when a pressure-sensitive adhesive layer containing a propylene-based oligomer is applied to a polypropylene-based substrate that is frequently used for coating film protection for automobiles, even when a small amount of propylene-based oligomer is used, the interfacial adhesive force between the substrate and the pressure-sensitive adhesive layer is improved. Markedly enhanced.

  In the present invention, it is optional to add known additives that are usually blended in this field to the polyolefin-based substrate. Examples of additives include stabilizers such as light-resistant agents and antioxidants that can be added to the adhesive layer, and lubricants, antistatic agents, rust inhibitors, pigments, and the like. For example, in the case of a surface protective film that is exposed to ultraviolet rays, such as a surface protective film that protects a coating film for automobiles, a weathering agent is preferably added to the polyolefin-based substrate.

  As a weathering agent blended in the polyolefin base material, an ultraviolet shielding agent and / or an ultraviolet stabilizer are preferably used.

  Examples of the ultraviolet shielding agent include inorganic pigments such as titanium oxide, zinc oxide, calcium carbonate, and carbon black. These may be used alone, or may be used by blending a plurality of them. Of these, titanium oxide is particularly preferably used because of its excellent ultraviolet shielding properties.

  Examples of the ultraviolet stabilizer include salicylic acid-based, benzophenone-based, benzotriazole-based, cyanoacrylate-based ultraviolet absorbers, and hindered amine-based light stabilizers. Only 1 type may be used for these and 2 or more types may be used together.

(Surface protection film)
In the surface protective film according to the present invention, the shear storage modulus of the adhesive layer at a frequency of 10 Hz is 4 × 10 ⁶ Pa or less at −30 ° C. More preferably, it is 3.5 × 10 ⁶ Pa or less.

  When the surface protective film is temporarily attached to the adherend and stored outdoors in winter, the temperature of the surface protective film may be lower than 0 ° C. In this case, in the conventional surface protective film, the adhesive force of the surface protective film is lowered, and the surface protective film may be peeled off naturally from the adherend. Furthermore, the surface protective film may be peeled off by wind pressure when transported by a carrier car or the like after pasting, and it may be necessary to perform pasting again.

  As a result of diligent study, the inventors of the present application have confirmed that the surface protective film is naturally peeled off when stored outdoors in winter and the peeling due to wind pressure during transportation is maintained at −5 ° C. between the adhesive layer and the adherend. It was found to correlate with force. Specifically, the holding force between the adhesive layer and the adherend at −5 ° C. is evaluated, and if the peeling rate at the time of 90 ° holding force evaluation with a load of 40 g of the surface protective film is 0.3 mm / s or less. It has been clarified that the surface protective film does not peel off from the adherend when stored outdoors in winter, maintains a temporary wearing state, and is hardly peeled off by wind pressure during transportation.

Furthermore, it has also been found that the holding force between the adhesive layer and the adherend at −5 ° C. is closely related to the shear storage modulus at −30 ° C. That is, for the first time by the inventor of the present invention, the shear storage modulus at −30 ° C. is closely related to the natural peeling phenomenon of the surface protective film when stored outdoors in winter and the peeling due to the wind pressure during transportation. If the shear storage modulus at −30 ° C. of the surface protective film is a specific value, that is, 4 × 10 ⁶ Pa or less, the surface protective film can be obtained when stored outdoors in winter. It turned out that it does not peel from a to-be-adhered body but maintains a temporary attachment state enough, and it is hard to peel off by the wind pressure at the time of transport.

  That is, by setting the shear storage modulus at −30 ° C. at a frequency of 10 Hz within the above specific range, the initial adhesive strength is particularly good, and the surface protective film is adhered to the adherend when stored outdoors in winter. Therefore, the surface protection film is extremely difficult to be peeled off even by the wind pressure during transportation.

In the surface protective film according to the present invention, the shear storage elastic modulus at 10 Hz of the pressure-sensitive adhesive layer is 2 × 10 ⁵ Pa or more at 70 ° C. When the shear storage elastic modulus at 70 ° C. is 2 × 10 ⁵ Pa or more, the adhesive strength is more excellent with time stability, and the adhesive strength is less likely to vary with time. When the shear storage elastic modulus at 70 ° C. is less than 2 × 10 ⁵ Pa, the adhesive force may vary with time.

Moreover, in the surface protective film which concerns on this invention, it is preferable that the tensile storage elastic modulus in the frequency of 10 Hz of the adhesion layer shall be 2.5 * 10 < ⁹ > Pa or more at -100 degreeC. By setting the tensile storage elastic modulus at −100 ° C. to 2.5 × 10 ⁹ Pa or more, it can be smoothly peeled off from the adherend by a human hand, and adhesive residue is hardly generated.

In the present invention, the shear storage elastic modulus at a frequency of 10 Hz of the adhesive layer is preferably in the range of 2 × 10 ^{5 to} 5 × 10 ⁶ Pa at 23 ° C. If it exceeds 5 × 10 ⁶ Pa, the surface protective film is easily peeled off from the adherend during transportation due to insufficient adhesive strength, and if it is less than 2 × 10 ⁵ , the workability in the peeling process is deteriorated or the paste is peeled off. There is a risk of remaining.

  By setting the tensile storage elastic modulus at −100 ° C. and the shear storage elastic modulus at 23 ° C. at a frequency of 10 Hz of the pressure-sensitive adhesive layer within the above specific range, (1) initial adhesive strength of the surface protective film, (2) Stability over time and (4) peeling workability can be further improved.

  In the present invention, a surface protective film suitable for protecting a coating film for automobiles, for example, has a polyolefin-based substrate containing the above-described weathering agent, and transmits ultraviolet rays in a wavelength range of 190 to 370 nm of the polyolefin-based substrate. It is a film for surface protection which has a pressure-sensitive adhesive layer having a rate of 10% or less and containing the rubber-based resin component and the tackifying resin described above.

  A coating film protecting film, particularly an automobile coating film protecting film has sufficient weather resistance when the ultraviolet transmittance in the wavelength range of 190 to 370 nm is set to 10% or less. A preferable ultraviolet transmittance is 1% or less. In order to achieve such a range, the surface protective film may be designed in consideration of the blending amount of the ultraviolet shielding agent or ultraviolet absorber and the thickness of the substrate. In addition, since the temperature rise of a coating-film surface can be suppressed, it is effective to mix | blend the ultraviolet-ray shielding agent which has heat ray reflective functions, such as titanium oxide.

  The surface protective film for protecting a coating film according to the present invention is temporarily attached to the coating film via an adhesive layer. For example, when ultraviolet light is irradiated to the temporarily-attached surface protective film, the ultraviolet light reaches the adhesive layer attached to the coating film through the polyolefin-based substrate. When the ultraviolet transmittance of the polyolefin-based substrate is in the specific range, not only the polyolefin-based substrate but also the adhesive layer attached to the coating film is difficult to deteriorate. Therefore, the adhesive layer attached to the coating film is unlikely to deteriorate, so that when the surface protective film is peeled off from the coating film, adhesive residue is hardly generated on the coating film surface. Furthermore, since the amount of ultraviolet rays passing through the surface protective film and reaching the coating film is also reduced, the coating film is hardly deteriorated by ultraviolet rays.

  As described above, the surface protective film of the present invention is suitably used as a surface protective film for protecting a coating film, but is not limited to a coating film and can be applied to various adherends. That is, it can be suitably used for protecting the adherend surface made of a material having polarity such as a synthetic resin such as an acrylic resin or a metal. Even in that case, no adhesive residue is likely to occur, and good peeling performance can be obtained. That is, the adherend surface to which the surface protective film of the present invention is applied is not particularly limited.

  The method for producing the surface protective film is not particularly limited. For example, a method of laminating and integrating the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer and the composition constituting the polyolefin-based substrate, or Examples thereof include a method of laminating a pressure-sensitive adhesive composition on a film-formed polyolefin-based substrate and laminating and integrating them.

  As a method of laminating and integrating the polyolefin base material and the pressure-sensitive adhesive composition by coextrusion, a known method such as an inflation method or a T-die method can be used. As a method for laminating the pressure-sensitive adhesive composition on a polyolefin-based substrate, a solution coating method for coating a pressure-sensitive adhesive solution, a dry lamination method, an extrusion coating method using a T-die, or the like is used. Among these, a co-extrusion method using a T-die is preferable because quality can be improved and production can be made economically. Further, when the solution coating method is performed, in order to increase the bonding strength between the base material layer and the adhesive layer, it is preferable to apply a primer or the like to the polyolefin base material in advance to perform a surface treatment.

  In the surface protective film according to the present invention, an adhesive layer containing a rubber-based resin component and a tackifying resin is laminated on a polyolefin-based substrate, and the rubber-based resin component is the specific styrene-based elastomer, and the rubber-based film Since paraffinic oil as a tackifying resin is contained in the adhesive layer in the range of 5 to 40 parts by weight with respect to 100 parts by weight of the resin component, as described above, (1) excellent initial adhesive strength, It can be reliably affixed to the surface of the adherend, thereby preventing dust from adhering to the surface of the adherend and preventing damage. Further, the surface protective film has (2) improved stability over time of adhesive force, (3) it is difficult to peel off from the adherend due to wind pressure during transportation, etc. (4) workability is good at the time of peeling, Further, (5) adhesive residue hardly occurs on the adherend after peeling, and (6) adhesion marks are hardly formed. Therefore, it is excellent in any of (1) initial adhesive strength, (2) stability of adhesive strength with time, (3) peeling performance by wind pressure, (4) peeling workability, (5) adhesive residue and (6) adhesion trace. A surface protective film can be provided.

  Hereinafter, the present invention will be clarified by giving examples and comparative examples of the present invention. The present invention is not limited to the following examples.

  FIG. 1 is a schematic front sectional view showing a surface protective film as one embodiment of the present invention. In the following examples and comparative examples, as shown in FIG. 1, a surface protective film 1 in which an adhesive layer 3 was laminated on one side of a polyolefin-based substrate 2 was produced and evaluated.

  Hereinafter, specific examples and comparative examples of the surface protective film will be described.

(Materials used)
[Rubber resin component]
SIBS (1): Kaneka Corporation, product number: Shibster 102T, block copolymer of styrene and isobutylene SIBS (2); Kaneka Corporation, product number: Shibster 073T, block copolymer of styrene and isobutylene

[Tackifying resin]
PA95: Paraffinic process oil manufactured by Kobe Oil Chemical Co., Ltd., trade name: SYNTAC PA95 (weight average molecular weight 400)
PA100; Kobe Oil Chemicals paraffinic process oil, trade name: SYNTAC PA100 (weight average molecular weight 600)
P470: Paraffinic process oil manufactured by Kobe Oil Chemical Co., Ltd., trade name: SYNTAC P470 (weight average molecular weight 1400)
Glysopearl V190; manufactured by BASF, liquid polyisobutylene resin, trade name: Glysopearl V190 (weight average molecular weight 3400)
B15; manufactured by BASF, product number: Opanol B15, polyisobutylene resin (weight average molecular weight 150,000)
Clearon LH; Yasuhara Chemical Co., Ltd., hydrogenated terpene resin, trade name: Clearon LH (weight average molecular weight 1000)

[Olefin oligomer]
Viscol 660P; manufactured by Sanyo Kasei Co., Ltd., propylene oligomer [polyolefin base material]
PB170A; Polypropylene PEX6800A manufactured by Sun Allomer Co., Ltd. Titanium oxide manufactured by Tokyo Ink Co., Ltd., trade name: PEX6800A White
UVT-52; a hindered amine light stabilizer manufactured by Tokyo Ink Co., Ltd., trade name: PPM UVT-52

(Example 1)
A pressure-sensitive adhesive composition containing 100 parts by weight of SIBS (1) as a styrene-based elastomer, 20 parts by weight of PA95 as a tackifier resin, and 2 parts by weight of biscol 660P as an olefin oligomer, PB170A 100 parts by weight, PEX6800A 20 A polypropylene substrate composition obtained by dry blending 3 parts by weight of UVT-52 and UVT-52 is coextruded by a T-die method, and a 10 μm thick adhesive layer is laminated on a 50 μm thick polypropylene substrate. A surface protective film was obtained.

(Examples 2 and 3 and Comparative Examples 1 to 6)
A surface protective film was obtained in the same manner as in Example 1 except that the rubber-based resin component and tackifying resin used and the blending ratio thereof were changed as shown in Table 1 below.

(Evaluation)
The following items were evaluated for each surface protective film obtained as described above.

(1) Shear storage elastic modulus The shear storage elastic modulus of each adhesive layer was −50 at a frequency of 10 Hz and a temperature increase rate of 6 ° C./min using a dynamic viscoelasticity spectrum measurement device (IT Measurement Control Co., Ltd., product number: DVA200). Each shear storage modulus at -30 ° C, 23 ° C, and 70 ° C was determined by measuring in the range of ° C to + 150 ° C.

(2) Tensile storage elastic modulus The tensile storage elastic modulus of each adhesive layer is −100 at a frequency of 10 Hz and a temperature increase rate of 6 ° C./min using a dynamic viscoelasticity spectrum measurement device (IT Measurement Control Co., Ltd., product number: DVA200). The tensile storage elastic modulus at -100 ° C. was determined by measuring in the range of from −50 ° C. to + 50 ° C.

(3) Initial adhesive strength Each surface protective film is applied to a coated steel sheet for automobiles (alkyd melamine coating, surface gloss 80%) in an environment of room temperature 23 ° C. and relative humidity 65% using a 2 kg pressure-bonded rubber roller. Then, each was pasted at a speed of 300 mm / min and allowed to stand in that state for 30 minutes, and then the 180 degree peel strength at 25 mm width was measured at a speed of 300 mm / min in accordance with JIS Z0237. The peel strength measured in this manner was taken as the initial adhesive strength.

(4) Initial peel force Each surface protection film is applied to a coated steel sheet for automobiles (alkyd melamine coating, surface gloss 80%) in an environment of room temperature 23 ° C. and relative humidity 65% using a 2 kg pressure-bonded rubber roller. Then, each was pasted at a speed of 300 mm / min and allowed to stand in that state for 30 minutes, and then the 180 degree peel strength at 25 mm width was measured at a speed of 30 m / min in accordance with JIS Z0237. The peel strength measured in this way was taken as the initial peel force.

(5) Adhesive strength with time After each surface protective film was attached to a coated steel sheet for automobiles in the same manner as in the case of measuring the initial peel strength in (4), it was left in that state in a gear oven at 70 ° C. for 7 days. In accordance with JIS Z0237, a 180 degree peel strength at a width of 25 mm was measured at a speed of 300 mm / min.

(6) Contamination assessment of adherend (adhesion trace)
Each surface protective film is applied to a coated steel sheet for automobiles (alkyd melamine coating film, surface gloss 80%) in an environment of room temperature 23 ° C. and relative humidity 65% using a 2 kg pressure-bonded rubber roller. A scissors were put and pasted at a speed of 300 mm / min. Thereafter, it was left in a constant temperature / humidity oven at 50 ° C. and a relative humidity of 95% for 7 days to peel off the surface protective film. The level | step difference of the said steel plate surface in the part to which the collar part of the surface protection film was affixed was measured using the surface shape measuring apparatus (VE1000, product made by Japan Veeco), and the adhesion trace was evaluated on the following evaluation criteria.

[Evaluation criteria for adhesion marks]
○: Step is less than 0.25 μm Δ: Step is from 0.25 μm to less than 0.4 μm ×: Step is 0.4 μm or more

(Adhesive residue A)
(5) Presence or absence of adhesive residue on the coating surface after time-dependent adhesive strength measurement was evaluated according to the following evaluation criteria.

(Adhesive residue B)
Each surface protection film is applied to a coating film in which the surface of a coated steel sheet for automobiles (alkyd melamine coating film, surface gloss 80%) is roughened by sandpaper (# 1200), using a 2 kg pressure roller, 300 mm / min. Each was pasted at a speed, and left in that state for 30 minutes. Next, after being left in a constant temperature bath at 70 ° C. for 7 days, 180 ° peeling at 25 mm width was performed at a rate of 300 mm / min while being heated to 80 ° C. The presence or absence of adhesive residue on the coating film surface at this time was evaluated according to the following evaluation criteria.

[Evaluation criteria for adhesive residue A and B]
○: No adhesive residue △: Very little adhesive residue was observed ×: Adhesive residue was generated

(7) Holding force Each surface protective film 25mm wide is coated with a 2kg pressure-bonded rubber roller on a coated steel sheet for automobiles (alkyd melamine coating, surface gloss 80%) in an environment of room temperature 23 ° C and relative humidity 65%. Each was used and left in an environment of 5 ° C. for 30 minutes. Thereafter, the 90 ° holding force was evaluated using a 40 g weight, and the peeling rate was calculated from the peeling distance and time.

(8) Peeling test by wind pressure Each surface protection film is cut to a width of 100 mm and pasted on a coated steel sheet for automobiles (alkyd melamine coating, surface gloss 80%) using a 2 kg pressure roller. It was left for 30 minutes in an ambient temperature atmosphere of -5 to 5 ° C.

  Next, the steel plate obtained above was mounted on the carrier fixed to the automobile roof, and after running on the highway at a speed of 80 km / h for 2 hours at an environmental temperature of −5 to 5 ° C., the film was peeled off. Was measured. This was evaluated 10 times per sample, the number of peelings of 10 mm or more was calculated, and the peeling performance by wind pressure was evaluated according to the following evaluation criteria.

[Evaluation criteria for peeling performance by wind pressure]
○: The number of peelings is 2 or less. Δ: The number of peelings is 3 or less. X: The number of peelings is 4 or more. The results are shown in Table 1 below.

The schematic front sectional drawing of the surface protection film as one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Surface protective film 2 ... Polyolefin-type base material 3 ... Adhesive layer

Claims (4)

A surface protective film in which an adhesive layer containing a rubber-based resin component and a tackifying resin is laminated on a polyolefin-based substrate,
The rubber resin component is a block copolymer of a styrene polymer block (A) and an isobutylene polymer block (B), a random copolymer block of a styrene polymer block (A), styrene and isobutylene. (B ′) a block copolymer and / or a styrene-based elastomer having a hydrogenated product thereof as a main skeleton,
The tackifying resin contains paraffinic oil;
The adhesive layer contains 5 to 40 parts by weight of the paraffinic oil with respect to 100 parts by weight of the rubber-based resin component,
The surface protective film, wherein the adhesive layer has a shear storage modulus at a frequency of 10 Hz of 4 × 10 ⁶ Pa or less at −30 ° C. and 2 × 10 ⁵ Pa or more at 70 ° C.   The surface protective film according to claim 1, wherein the adhesive layer further contains an olefin oligomer.   The surface protection film according to claim 2, wherein the adhesive layer contains the olefin oligomer at a ratio of 10 parts by weight or less with respect to 100 parts by weight of the rubber resin component.   A surface protective film used as a film for protecting a coating film, wherein the polyolefin base material contains a weathering agent, and the ultraviolet transmittance in the wavelength range of 190 to 370 nm of the polyolefin base material is 10% or less. The surface protection film of any one of Claims 1-3.

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