JP2009242763A - Coating film protective sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-performance coating film protective sheet highly preventing a residual adhesive and excellently maintaining proper adhesiveness even if being exposed to a temperature-rising environment. <P>SOLUTION: The coating film protective sheet is provided with a sheet-shaped base material, a primer layer formed on one side of the base material, and a polyisobutylene self-adhesive layer formed via the primer layer. The primer layer principally consists of a chlorinated polyolefin resin wherein a glass transition temperature obtained by the DSC measurement performed while elevating the temperature from -10&deg;C to 200&deg;C at a rate of 10&deg;C/min is &ge;10&deg;C. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a coating film protective sheet for protecting a coating film from damage such as scratches and dirt.

  Transport, storage, curing, construction, etc. (hereinafter sometimes referred to as “transfer”) of articles having a coating film (for example, painted automobiles and parts thereof, or metal plates such as steel plates and molded products thereof). For the purpose of preventing damage to the surface of the coating film during the process, a technique for protecting the coating film by bonding a protective sheet is known. The coating film protective sheet used for this purpose generally has a pressure-sensitive adhesive layer on one side of a sheet-like substrate, and is adhered to the adherend surface (the coating film to be protected) via the pressure-sensitive adhesive layer. In this way, the protection purpose can be achieved. Patent documents 1 and patent documents 2 are illustrated as a prior art literature about this kind of paint film protection sheet.

JP 2001-240820 A Japanese Patent Laid-Open No. 9-3420

  In recent years, as the automobile industry has become active, the internationalization of logistics has been progressing, and the environment in which articles with paint films (painted articles) can be exposed during transportation is cold from the tropical regions. It has become widespread to the ground. On the other hand, as part of improving the value of products (automobiles, etc.), demands for improving the appearance design of coating films are becoming more sophisticated. As one of such requirements, when the coating film protective sheet that has finished its protective role is peeled (removed) from the surface of the coating film, a deposit (typically one of the pressure-sensitive adhesives constituting the pressure-sensitive adhesive layer) is derived from the sheet. Part) is a technique that more reliably prevents an event (glue residue) remaining on the surface of the coating film. For example, not only a coating film with high smoothness such as the surface of a new car but also a coating film with a surface state that is disadvantageous from the viewpoint of preventing adhesive residue such as a coating film after use (polishing repair surface, etc.) Even when used for protecting a coating film, it would be beneficial to provide a coating film protective sheet that can exhibit a high level of adhesive residue prevention (residue resistance).

  The present invention prevents the above adhesive residue to a higher degree and protects the coating film with excellent performance to maintain moderate adhesiveness even when used in an environment where the temperature rises due to outdoor transfer or the like. One purpose is to provide seats. Another object of the present invention is to provide a method for producing such a coating film protective sheet.

  The present inventor has found that the above problem can be solved by interposing a specific primer between the polyisobutylene-based pressure-sensitive adhesive layer and the substrate, and has completed the present invention.

  The coating film protective sheet provided by the present invention includes a sheet-like base material, an undercoat layer provided on one side of the base material, and a polyisobutylene-based pressure-sensitive adhesive layer provided via the undercoat layer. Is provided. Here, the primer layer has a glass transition temperature of 10 ° C. or higher determined by DSC measurement (differential scanning calorimetry) in which the temperature is increased from −10 ° C. to 200 ° C. under the condition of 10 ° C./min. Mainly resin.

  According to the coating film protective sheet having such a configuration (hereinafter, also simply referred to as “protective sheet”), the pressure-sensitive adhesive is obtained by interposing a chlorinated polyolefin-based resin between the polyisobutylene-based pressure-sensitive adhesive layer and the base material. The adhesion of the layer to the substrate (anchoring property) can be improved, and the phenomenon that the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer remains on the adherend side when the protective sheet is peeled off (that is, adhesive residue) can be prevented to a higher degree. . Here, as the chlorinated polyolefin resin constituting the primer layer, a specific chlorinated polyolefin resin whose behavior (DSC characteristic) for the DSC measurement satisfies a predetermined condition is used. As a result, the provision of a primer layer has the ability to maintain an appropriate adhesive strength regardless of other characteristics (for example, aging and thermal history (temperature rise exceeding normal temperature, etc.) after sheet application, that is, adhesive strength. Stability). Therefore, it is possible to realize a protective sheet that achieves a high level of both anti-glue resistance and other characteristics (such as peeling workability).

  In a preferred embodiment of the protective sheet disclosed herein, the base material is composed of a polyolefin resin sheet. The polyolefin resin sheet contains a polypropylene resin (hereinafter also referred to as “PP resin”) alone as a resin component, or a PP resin and a polyethylene resin (hereinafter referred to as “PE resin”) as a resin component. It is preferable that it is a polyolefin-based resin sheet. According to the combination of the base material having such a structure and the polyisobutylene-based pressure-sensitive adhesive layer, the adhesion of the pressure-sensitive adhesive layer to the base material can be more effectively improved by the undercoat layer of the above composition. Therefore, better adhesive residue resistance can be realized. Moreover, the said polyolefin resin sheet may be equipped with the characteristic suitable as a base material of a coating-film protection sheet (For example, the automobile coating-film protection sheet used for protection of a motor vehicle or its components). A resin sheet having such a composition is also preferable from the viewpoint of recyclability and the like.

  The chlorinated polyolefin resin may be a chlorinated polyolefin resin containing a polyolefin chain graft-modified with an acid (that is, an acid-modified chlorinated polyolefin resin), and is not subjected to such acid modification ( It may be an unmodified type) chlorinated polyolefin resin. For example, an unmodified type chlorinated polyolefin resin can be preferably employed.

In a preferred embodiment, the polystyrene-converted mass average molecular weight of the chlorinated polyolefin resin is about 3 × 10 ⁴ or more (typically about 3 × 10 ^{4 to} 20 × 10 ⁴ ). According to the undercoat layer of such a composition, the adhesiveness of the pressure-sensitive adhesive layer to the substrate can be more effectively improved while suppressing the influence on other properties.

According to the present invention, there is also provided a method for producing a coating film protective sheet having a configuration in which a polyisobutylene-based pressure-sensitive adhesive layer is provided on one side of a substrate via an undercoat layer. The method uses a chlorinated polyolefin resin having a glass transition temperature of 10 ° C. or higher as a resin material for forming an undercoat layer, which is determined by DSC measurement in which the temperature is increased from −10 ° C. to 200 ° C. at a rate of 10 ° C./min. Can be included. Moreover, the process of forming the primer layer which has this chlorinated polyolefin-type resin as a main component on the single side | surface of a base material may be included. Furthermore, it may include a step of forming a polyisobutylene-based pressure-sensitive adhesive layer on the primer layer.
According to such a production method, it is possible to efficiently produce a coating film protective sheet in which the adhesive residue resistance and other characteristics (such as peeling workability) are compatible at a high level. The production method can be preferably employed, for example, as a method for producing any coating film protective sheet disclosed herein.

  Hereinafter, preferred embodiments of the present invention will be described. Note that matters other than matters specifically mentioned in the present specification and necessary for the implementation of the present invention can be grasped as design matters of those skilled in the art based on the prior art in this field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

  The coating film protective sheet according to the present invention (for example, an automotive coating film protective sheet used for protecting automobiles and parts thereof) is a predetermined primer layer between a sheet-like substrate and a polyisobutylene-based pressure-sensitive adhesive layer. Is provided. For example, as schematically shown in FIG. 1, the coating film protective sheet 10 has a configuration in which an undercoat layer 4 is provided on one side of a substrate 1 and an adhesive layer 2 is provided on the undercoat layer 4. The pressure-sensitive adhesive layer 2 is attached to an adherend (an article to be protected, for example, an article having a coating film such as an automobile or its parts). The protective sheet 10 before use (that is, before sticking to an adherend) has a release liner (not shown) in which the surface (adhesive surface) of the pressure-sensitive adhesive layer 2 is at least a release surface on the pressure-sensitive adhesive layer side. It can be in a protected form. In addition, the other surface (back surface) of the base material 1 is a release surface, and the protective sheet 10 is wound in a roll shape so that the pressure-sensitive adhesive layer 2 comes into contact with the other surface to protect the surface. The form of the protective sheet 10 may be used.

  The technology disclosed herein is a resin sheet mainly composed of a resin component such as polyolefin or polyester (typically a resin film formed by molding a resin composition mainly composed of such a resin component into a film shape). It can apply preferably to the coating-film protection sheet which uses as a base material. A particularly preferable application target is a coating film protective sheet in which the resin component constituting the substrate is mainly a polyolefin-based resin (that is, using a polyolefin-based resin sheet as a substrate). A substrate having such a composition is preferable from the viewpoint of recyclability and the like.

  As the polyolefin-based resin sheet (film), it is preferable to employ a resin component that mainly comprises a PP resin (in other words, the resin component exceeds 50% by mass and includes a PP resin). it can. For example, a resin sheet in which approximately 60% by mass or more (more preferably approximately 75% by mass or more) of the resin component is PP resin is preferable. From the viewpoint of heat resistance and the like, a resin sheet in which a continuous structure (continuous phase) of PP resin is formed can be preferably used. The resin component may be a resin sheet substantially composed of one or two or more types of PP resins (that is, containing a PP resin alone as a resin component). Thus, the protective sheet using the resin sheet having the continuous structure of the PP resin as a base material causes a situation where the protective sheet floats from the adherend (coating film) due to a thermal history such as a temperature rise during outdoor curing, for example. It is preferable because it is easy to prevent. The substrate may have a single layer structure or a multilayer structure of two or more layers. In the case of a multilayer structure, at least one layer is preferably a layer having a continuous structure of the PP resin.

Various polymers (propylene-based polymers) containing propylene as components can be used as the PP resin for the base material. The concept of propylene-based polymer here includes, for example, the following polypropylene.
Propylene homopolymer (homopolypropylene). For example, isotactic polypropylene.
A random copolymer (random polypropylene) of propylene and another α-olefin (typically, one or more selected from ethylene and an α-olefin having 4 to 10 carbon atoms). Preferably, a random polypropylene containing propylene as a main monomer (main constituent monomer, that is, a component occupying 50% by mass or more of the whole monomer). For example, random polypropylene obtained by random copolymerization of 96 to 99.9 mol% of propylene and 0.1 to 4 mol% of the other α-olefin (preferably ethylene and / or butene).
A copolymer obtained by block copolymerization of propylene with another α-olefin (typically, one or more selected from ethylene and an α-olefin having 4 to 10 carbon atoms) (those having propylene as the main monomer) Block copolymer (block polypropylene), which further comprises a rubber component, which is typically composed of at least one of propylene and the above-mentioned other α-olefins as a by-product. For example, a polymer obtained by block copolymerization of 0.1 to 10 mol% of the above-mentioned other α-olefin (preferably ethylene and / or butene) with 90 to 99.9 mol% of propylene, propylene and the above-mentioned other products as by-products A block polypropylene further comprising a rubber component containing at least one of α-olefins.

  The PP resin for the base material may be substantially composed of one or two or more of such propylene polymers (such as the polypropylene), and a large amount of rubber component is added to the propylene polymer. It may be a reactor blend type obtained by copolymerization or a dry blend type thermoplastic olefin resin (TPO) or thermoplastic elastomer (TPE) obtained by mechanically dispersing the rubber component. In addition to a polymerizable functional group, a PP resin containing a copolymer of a monomer having another functional group (functional group-containing monomer) and propylene, a PP resin obtained by copolymerizing such a functional group-containing monomer with a propylene-based polymer, etc. There may be.

  When the polyolefin resin sheet contains another resin component in addition to the PP resin, as a suitable example of the other resin component, an olefin polymer having ethylene or an α-olefin having 4 or more carbon atoms as a main monomer is a main component. And a polyolefin resin (such as a PE resin containing an ethylene polymer as a main component). For example, a polyolefin resin sheet containing a PE resin and a PP resin as resin components can be preferably used as the base material of the protective sheet disclosed herein.

As the PE resin for the substrate, any of high-density polyethylene and low-density polyethylene (high-density, medium-density and low-density polyethylene as defined in the former JIS K6748: 1995) can be used. Moreover, PE resin containing the copolymer of ethylene and another alpha olefin (for example, C3-C10 alpha olefin) may be sufficient. Preferable examples of the α-olefin include 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like. In addition to the polymerizable functional group, a PE resin containing a copolymer of a monomer having another functional group (functional group-containing monomer) and ethylene, a PE resin obtained by copolymerizing such a functional group-containing monomer with an ethylene polymer, etc. There may be. Examples of the copolymer of ethylene and a functional group-containing monomer include, for example, ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), and ethylene-acrylic. Methyl acid copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl methacrylate copolymer (EMMA), ethylene- (meth) acrylic acid (ie, acrylic acid and / or methacrylic acid) ) The copolymer is crosslinked with a metal ion. For example, density 0.94 g / cm ³ or less (typically 0.9~0.94g / cm ³⁾ of low density polyethylene (preferably linear low density polyethylene) or medium density polyethylene, density 0.86～ 0.90 g / cm ^{3 of} an ethylene-α-olefin copolymer or the like can be preferably used as a component of the polyolefin resin sheet (preferably a resin sheet containing a PE resin and a PP resin).

  The resin sheet (preferably polyolefin resin sheet) used as the base material of the protective sheet disclosed herein may contain an appropriate component that is allowed to be contained in the base material as necessary. For example, pigments (typically inorganic pigments), fillers, antioxidants, light stabilizers such as radical scavengers and ultraviolet absorbers, additives such as slip agents and antiblocking agents can be appropriately blended.

  Examples of materials that can be preferably used as the pigment or filler include inorganic powders such as titanium oxide, zinc oxide, and calcium carbonate. The blending amount of the inorganic pigment and filler may be appropriately set in consideration of the degree of effect obtained by the blending and the moldability of the substrate according to the resin sheet molding method (extrusion molding, cast molding, etc.). it can. Usually, the blending amount of the inorganic pigment and the filler (the total amount when blending plural kinds) is about 2 to 20 parts by mass (more preferably about 5 to 15 parts by mass) with respect to 100 parts by mass of the resin component. Part).

  Examples of antioxidants include those containing alkylphenols, alkylene bisphenols, thiopropylene acid esters, organic phosphite esters, amines, hydroquinones, hydroxylamines and the like as active ingredients. Examples of light stabilizers include those containing benzotriazoles, hindered amines, benzoates and the like as active ingredients. Each of these additives can be used alone or in combination of two or more. The compounding amount of the additive can be, for example, about the same as the usual compounding amount in the field of resin sheets used as a base material of a coating film protective sheet (for example, an automobile coating film protective sheet).

  The resin sheet (preferably a polyolefin resin sheet) can be produced by appropriately adopting a conventionally known general film forming method. For example, a molding material containing the above resin component (preferably a resin component containing PP resin alone or a resin component containing PP resin as a main component and PE resin as an auxiliary component) and additives blended as necessary. A method of extrusion molding can be preferably employed.

The surface of the substrate (typically a resin sheet) 1 shown in FIG. 1 where the pressure-sensitive adhesive layer 2 is provided via the primer layer 4 is subjected to acid treatment, corona discharge treatment, ultraviolet irradiation treatment, plasma treatment. A surface treatment such as the above may be applied. Further, on the surface (back surface) opposite to the surface on which the pressure-sensitive adhesive layer 2 is provided in the base material 1, a release treatment (for example, general silicone-based, long-chain alkyl-based, fluorine-based) is performed as necessary. Etc.) (typically, a treatment for applying a release treatment agent such as 0.01 to 0.1 μm in the form of a thin film) may be performed. By performing such a mold release treatment, effects such as easy rewinding of the roll of the coating film protection sheet 10 can be obtained.
The thickness of the substrate can be appropriately selected according to the purpose. Usually, the thickness is appropriately about 20 μm to 100 μm, preferably about 30 μm to 70 μm (for example, about 35 μm to 60 μm). The base material having such a thickness is suitable as a base material for an automobile paint film protective sheet, for example.

The polyisobutylene-based pressure-sensitive adhesive layer provided in the coating film protective sheet disclosed herein is a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition having an isobutylene-based polymer as a base polymer (the main component of the polymer component). possible.
The isobutylene-based polymer may be a homopolymer of isobutylene (homoisobutylene) or a copolymer having isobutylene as a main monomer. The copolymer includes, for example, a copolymer of isobutylene and normal butylene, a copolymer of isobutylene and isoprene (regular butyl rubber, chlorinated butyl rubber, brominated butyl rubber, partially crosslinked butyl rubber, etc.), vulcanized products and modified products thereof. (For example, those modified with a functional group such as a hydroxyl group, a carboxyl group, an amino group, and an epoxy group). Examples of the isobutylene polymer preferably used from the viewpoint of the stability of the adhesive strength (for example, the property that the adhesive strength does not increase excessively due to aging or heat history) include homoisobutylene and isobutylene-normal butylene copolymers. Of these, homoisobutylene is preferable.

The molecular weight of the isobutylene polymer is not particularly limited, and for example, a polymer having a mass average molecular weight (Mw) of about 10 × 10 ^{4 to} 150 × 10 ⁴ can be appropriately selected and used. As an isobutylene-based polymer that can be preferably used, Mw is about 20 × 10 ⁴ to 70 × 10 ⁴ (preferably about 30 × 10 ^{4 to} 60 × 10 ⁴ , more preferably about 35 × 10 ⁴ to 50 × 10 ⁴ ). Examples are isobutylene polymers.
In addition, the isobutylene-based polymer is an isobutylene-based polymer (preferably, the molecular weight is decreased so as to achieve the above-described preferable mass average molecular weight) by subjecting a higher molecular weight isobutylene-based polymer to a slicking treatment. Shak solution processing body). The crushing treatment is preferably performed so as to obtain an isobutylene polymer having a Mw of about 10% to 80% before the crushing treatment. Further, it is preferable to carry out so that the number average molecular weight (Mn) of about ¹⁰ × 10 ⁴ ~40 × 10 4 isobutylene polymer is obtained. Such shank solution processing can be performed based on, for example, the description of Japanese Patent No. 3878700.

  The polyisobutylene-based pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer may have one or two or more types selected from such isobutylene-based polymers as a base polymer. The polyisobutylene-based pressure-sensitive adhesive may contain a polymer other than the polyisobutylene-based polymer as a subcomponent in addition to the above base polymer. Examples of such polymers include poly (meth) acrylic acid esters, polybutadiene, polystyrene, polyisoprene, polyurethane, polyacrylonitrile, polyamide and the like. The content of these polymers other than the polyisobutylene-based polymer is usually preferably 10% by mass or less of the entire polymer component contained in the polyisobutylene-based adhesive. An adhesive that does not substantially contain a polymer other than polyisobutylene may be used.

  Various additions such as tackifiers, softeners, pigments, fillers, antioxidants, light stabilizers (radical scavengers, ultraviolet absorbers, etc.) and other stabilizers are added to the polyisobutylene-based pressure-sensitive adhesive. An agent can be blended as necessary. Examples of tackifiers that can be preferably used include alkylphenol resins, terpene phenol resins, epoxy resins, coumarone indene resins, rosin resins, terpene resins, hydrogenated products thereof, and the like. Examples of the softener include process oil and petroleum softener. Examples of materials that can be preferably used as the pigment or filler include inorganic powders such as titanium oxide, zinc oxide, calcium oxide, magnesium oxide, and silica. Examples of antioxidants include those containing alkylphenols, alkylene bisphenols, thiopropionic esters, organic phosphites, amines, hydroquinones, hydroxylamines and the like as active ingredients. Examples of light stabilizers include those containing benzotriazoles, hindered amines, benzoates and the like as active ingredients. Each of these additives can be used alone or in combination of two or more. The compounding quantity of an additive can be made into the same grade as the normal compounding quantity in the field | area of the adhesive for coating-film protection sheets (for example, automobile coating-film protection sheet), for example.

  The thickness of an adhesive layer is not specifically limited, It can determine suitably according to the objective. Usually, it is appropriate to be about 2 μm to 30 μm, preferably about 3 μm to 25 μm, and more preferably about 5 μm to 20 μm. For example, the above range can be preferably adopted as the thickness of the pressure-sensitive adhesive layer provided in the automobile paint film protective sheet.

  In the technique disclosed herein, an undercoat layer is interposed between the base material and the pressure-sensitive adhesive layer. The chlorinated polyolefin resin constituting the main component of the primer layer is characterized by having predetermined DSC characteristics. That is, a chlorinated polyolefin resin having a glass transition temperature (Tg) of 10 ° C. or higher (typically 10 to 40 ° C.) determined by DSC measurement in which the temperature is increased from −10 ° C. to 200 ° C. at a rate of 10 ° C./min. It is. A chlorinated polyolefin resin having a Tg of 15 ° C. or higher (typically 15 to 30 ° C., for example, 15 to 25 ° C.) is preferable, and a resin having a Tg of 17 ° C. or higher (typically 17 to 25 ° C.) is more preferable.

  As a resin material for forming the primer layer, by selecting a resin material satisfying the DSC characteristics from various chlorinated polyolefin resins, a primer layer mainly composed of the chlorinated polyolefin resin (the chlorine It can be an undercoat layer substantially composed of a modified polyolefin-based resin.) To effectively improve the adhesive residue resistance and maintain the adhesive strength stability substantially equivalent to the case where the undercoat layer is not provided. can do. On the other hand, in the primer layer using a chlorinated polyolefin resin whose glass transition temperature required by the DSC measurement is too low or too high than the above value, the effect of improving the adhesive residue resistance by providing the primer layer May not be sufficiently obtained, and there is a tendency that the adhesive strength is excessively increased due to a temperature increase after the sheet is stuck (such as when the article to be protected is stored outdoors). An excessive increase in the adhesive strength is not preferable because it may cause a decrease in the workability of peeling when the protective sheet that has finished its protective role is removed.

  The DSC measurement can be performed using a commercially available DSC measurement apparatus capable of measurement in the temperature range (for example, a differential scanning calorimeter manufactured by SII Nano Technology, model “DSC6220”, etc.). As measurement data, the sample was heated from −10 ° C. to 200 ° C. at a heating rate of 10 ° C./min, then rapidly cooled, and then heated again from −10 ° C. to 200 ° C. at a heating rate of 10 ° C./min. It is preferable to adopt the time value. At least in the temperature range from -10 ° C to 200 ° C, heating is started at a temperature lower than -10 ° C (eg, -40 ° C) on the condition that heating is performed at a rate of temperature increase of 10 ° C / min. In addition, the temperature may be raised to a temperature higher than 200 ° C. However, it is preferable that the heating before obtaining the measurement data is limited to a range up to about 250 ° C.

  As the resin material for forming the primer layer, an appropriate chlorinated polyolefin resin can be used as long as the DSC characteristics are satisfied. The chlorinated polyolefin resin may have a chlorinated olefin polymer as a main component. It may be a chlorinated polyolefin resin substantially composed of a chlorinated olefin polymer. The olefin polymer (raw material) used for chlorination is typically an olefin polymer having an α-olefin having about 2 to 10 carbon atoms as a main monomer. Such α-olefin homopolymers (polyethylene, polypropylene, etc.) may be used, and two or more α-olefin copolymers (ethylene-propylene copolymer, ethylene-propylene-butene copolymer, etc.). It may be a copolymer of one or more α-olefins and other monomers. For example, an olefin polymer having propylene as a main monomer (such as the above-described homopolypropylene, random polypropylene, block polypropylene, etc.) is preferable. A method for chlorinating such an olefin polymer is not particularly limited, and an appropriate method may be selected as appropriate from various conventionally known methods. For example, a method in which chlorine gas is allowed to act on the olefin polymer under heating conditions can be preferably employed.

  The chlorine content of the chlorinated polyolefin resin is not particularly limited, and for example, 5% by mass or more (typically about 5 to 60% by mass) can be used. Usually, a chlorinated polyolefin-based resin having a chlorine content of about 10% by mass or more (typically about 10 to 50% by mass) is preferable, and one having about 20 to 40% by mass is more preferable. In the case of a chlorinated polyolefin resin having a chlorine content that is too low or too high than the above value, the effect of improving the adhesiveness of the pressure-sensitive adhesive layer to the substrate may tend to be reduced. Moreover, it is desirable to avoid the use of a chlorinated polyolefin resin having a chlorine content that is higher than the above value from the viewpoint of environmental impact.

The molecular weight of the chlorinated polyolefin resin (for example, chlorinated PP resin) is not particularly limited. For example, Mw in terms of polystyrene is, for example, about 3 × 10 ⁴ or more (typically about 3 × 10 ^{4 to} 20 × 10 ^4). ) Can be used. A chlorinated polyolefin resin having a Mw of about 3 × 10 ⁴ to 15 × 10 ⁴ is preferable, more preferably about 3 × 10 ⁴ to 10 × 10 ⁴ , and still more preferably about 3 × 10 ^{4 to} 6 × 10 ⁴ . is there. If the chlorinated polyolefin resin has Mw lower than the above value, the cohesive force may be insufficient, and the effect of improving the adhesiveness of the pressure-sensitive adhesive layer to the base material may not be exhibited properly. In the case of a chlorinated polyolefin-based resin having Mw that is higher than the above value, it may be difficult to form a uniform primer layer. Although not particularly limited, a chlorinated polyolefin resin having a Mw / Mn of about 3 to 8 (more preferably about 5 to 7) can be preferably used.

  The chlorinated polyolefin resin used in the technology disclosed herein may be an acid-modified chlorinated polyolefin resin. For example, it may be a chlorinated polyolefin resin that has been acid-modified by allowing an organic acid (preferably an α, β-unsaturated carboxylic acid) and / or its anhydride to act (typically a graft reaction). By such acid modification, the polyolefin chain constituting the olefin polymer is typically graft-modified to form an acid-modified polyolefin chain. For the acid modification, for example, one or more selected from α, β-unsaturated carboxylic acids such as maleic acid, fumaric acid, itaconic acid, and acrylic acid, and anhydrides thereof can be used. Among these, preferred are acrylic acid, acrylic acid anhydride and maleic anhydride.

  Examples of commercially available chlorinated polyolefin resins that can be preferably used as the resin material for forming the primer layer include chlorinated polyolefin resins manufactured by Toyo Kasei Kogyo Co., Ltd., trade names “Hardren 14-ML”, “Hardlen”. 14-LLB "and the like.

Various additives such as pigments, fillers, antioxidants, light stabilizers (radical scavengers, UV absorbers, etc.) and other stabilizers are required for the primer layer in the technology disclosed herein. It can be blended according to. As these additives, the same additives as those that can be blended in the base material or the pressure-sensitive adhesive layer can be used in a usual amount.
The thickness of the primer layer is not particularly limited, and can be appropriately determined within a range where a desired effect of improving the adhesive residue resistance is achieved. Although not particularly limited, it is usually appropriate that the thickness of the primer layer is about 0.01 μm to 5 μm, preferably about 0.02 μm to 2 μm (for example, about 0.02 μm to 1 μm). . The thickness of the primer layer may be about 0.02 μm or more and less than 0.5 μm (for example, about 0.02 μm to 0.3 μm). For example, the above range can be preferably adopted as the thickness of the primer layer in the automobile paint film protective sheet. If the thickness of the primer layer is too smaller than the above range, it may be difficult to achieve the desired effect of improving the residual resistance. If the thickness of the primer layer is too larger than the above range, the influence on other properties (such as stability of adhesive strength) may become apparent.

  The primer layer is formed by, for example, forming a primer layer in which a primer layer forming material including the chlorinated polyolefin resin having the DSC characteristics and an additive blended as necessary is dissolved or dispersed in an appropriate solvent. Composition (manufacturing, purchasing, etc.) and applying the composition to the surface of the base material (which may be a surface that has been surface-treated as described above) in a thin film form (typically applied) And preferably formed by drying. Alternatively, the primer layer may be formed by a method in which a heated melt of the primer layer forming material is applied to the surface of the base material and cooled and solidified. The primer layer is typically formed continuously throughout the entire range in which the pressure-sensitive adhesive layer is formed, but depending on the purpose and application, it may have a regular or random pattern such as a dot or stripe. It may be formed.

The formation of the polyisobutylene-based pressure-sensitive adhesive layer can be performed according to a method for forming a pressure-sensitive adhesive layer in a known pressure-sensitive adhesive sheet. For example, a pressure-sensitive adhesive composition is prepared (manufacturing, purchasing, etc.) in which a pressure-sensitive adhesive layer-forming material containing a polymer component mainly composed of an isobutylene polymer and an additive blended as necessary is dissolved or dispersed in a suitable solvent. And preferably adopting a method (direct method) in which the composition is applied directly to the surface of the primer layer (typically applied) and dried to form an adhesive layer on the primer layer. Can do. Further, the pressure-sensitive adhesive composition is applied to a surface having good releasability such as a release liner or a release-treated substrate back surface and dried to form a pressure-sensitive adhesive layer on the surface, and the pressure-sensitive adhesive layer A method (transfer method) may be employed in which the is transferred onto the surface of the primer layer. The pressure-sensitive adhesive layer is typically formed continuously, but may be formed in a regular or random pattern such as a dot or stripe depending on the purpose and application.
In addition, when drying the adhesive composition provided on the primer layer in the direct method, drying can be promoted by heating as necessary. Although it does not specifically limit, For example, the drying temperature of about 60-130 degreeC can be employ | adopted preferably.

  The coating film protective sheet according to the present invention is, for example, an article to be protected that has been coated with a paint having various compositions such as acrylic, polyester, alkyd, melamine, urethane, or a composite thereof (the above-mentioned coating treatment). Articles having a coating film formed by, for example, automobile bodies and parts thereof, metal plates such as steel plates or molded products thereof, etc. It can be preferably used for the purpose of protecting from contact and the like. Especially for automobiles that are highly likely to be stored outdoors for a long period of time or transported to tropical and other climatic areas, and have a high level of demand for the appearance design of coating films (for example, for exterior coatings on automobile bodies). It is suitable as a protective sheet.

In practicing the present invention, it is not necessary to clarify the reason why the adhesive resistance is improved while suppressing the influence on other characteristics by adopting the above configuration, but it is assumed as follows, for example. That is, the chlorinated polyolefin resin constituting the primer layer has a high chemical affinity between the polyolefin chain in the skeleton and the polyisobutylene adhesive, and therefore the adhesive layer and the substrate (preferably chlorinated). It is possible to effectively enhance the adhesion with a polyolefin-based resin sheet (polyolefin-based resin sheet having high adhesion with the polyolefin-based resin) and improve the anti-glue resistance.
However, chlorinated polyolefin resins generally tend to diffuse into the polyisobutylene pressure-sensitive adhesive because of the high chemical affinity. When the chlorinated polyolefin resin diffused in the adhesive reaches the vicinity of the surface of the adhesive layer, the polar functional group of the coating film (adherent) and the polar functional group of the chlorinated polyolefin resin It can become a factor which raises the adhesive strength of a protection sheet by interaction. The diffusion can be further promoted under temperature conditions exceeding room temperature. For this reason, the above-mentioned increase in adhesive strength is particularly likely to occur in automobile protective sheets that are expected to be stored outdoors for long periods of time or transported in tropical regions.

In the coating film protective sheet according to the present invention, a chlorinated polyolefin resin having a Tg of 10 ° C. or higher (preferably 15 ° C. or higher) is particularly selected and used. A chlorinated polyolefin resin having such a Tg is unlikely to diffuse into the pressure-sensitive adhesive layer even with the passage of time or temperature. Therefore, it is considered that the increase in adhesive strength can be suppressed even when used for forming the primer layer.
Moreover, since the polyisobutylene-type adhesive which comprises the adhesive layer of this protective sheet has a big difference in solubility parameter (SP value) with a coating film (for example, coating film for motor vehicles), between both It is preferable because mass transfer is unlikely to occur and traces of the protective sheet attached to the coating film are unlikely to occur. Further, such an adhesive layer has a high elastic modulus and is suitable as a re-peelable adhesive.

  Several examples relating to the present invention will be described below, but the present invention is not intended to be limited to those shown in the examples. In the following description, “parts” and “%” are based on the mass of the nonvolatile content unless otherwise specified.

In addition, the mass average molecular weight described in the following examples is a value in terms of polystyrene obtained by measurement under the following conditions using a GPC apparatus (Waters product, model “GPC-150c”, plus type). .
[Mass average molecular weight measurement conditions]
Sample solution: 0.10% (w / w) o-dichlorobenzene solution Sample injection amount: 500 μL
・ Mobile phase: o-dichlorobenzene ・ Flow rate: 1.0 mL / min ・ Column temperature: 140 ° C.
-Column: Tosoh Corporation product, model number “GMH ₆ -HT 30 cm” (2) and “GMH ₆ -HTL 30 cm” (2)
・ Detector: Differential refractometer

For DSC measurement, a differential scanning calorimeter, model “6220” manufactured by SII Nanotechnology Inc. was used. The measurement conditions are as follows.
[DSC measurement conditions]
-Preparation of sample: About 7 mg of the measurement object was weighed, dried at 100 ° C for 20 minutes, and then sealed in an aluminum container.
Measurement temperature range: −40 ° C. to 200 ° C.
Temperature program: The sample was heated from the lower end temperature to the upper end temperature of the measurement temperature range at a rate of temperature increase of 10 ° C./min, and then rapidly cooled. Then, the value when it heated from the lower end temperature of the said measurement temperature range to the upper end temperature again with the temperature increase rate of 10 degree-C / min was made into measurement data. That is, DSC measurement was performed twice consecutively, and DSC measurement data was acquired at the second temperature increase.

<Example 1>
38 parts of a propylene homopolymer (product of Nippon Polypro Co., Ltd., trade name “Novatech PP FY4”), 37 parts of ethylene / propylene block copolymer (product of the company, trade name “Novatech PP BC3F”), linear low density polyethylene (LLDPE) (Nippon Polyethylene Corporation product, trade name “Kernel KF380”) 15 parts, rutile type titanium dioxide (Ishihara Sangyo product, trade name “TIPAQUE CR-95”) 10 parts and light stabilizer (Ciba Specialty Chemicals product, A base molding material containing 0.2 part of a trade name “Chimassorb 944”) is melt-kneaded in a film molding machine, extruded from a T die of the molding machine, and a base material (polyolefin resin) having a thickness of 35 μm. Film).

  Maleic anhydride-modified chlorinated polyolefin resin (product of Toyo Kasei Kogyo Co., Ltd., trade name “Hardlen 14-ML”) was diluted to an appropriate concentration with an organic solvent to prepare a primer solution. After the corona discharge treatment is performed on one surface of the base material obtained above, the primer solution is applied to the treated surface with a Mayer bar # 5 and dried to give a thickness of 0. A primer layer of 03 to 0.15 μm was formed.

Benzoyl peroxide was added to an n-heptane solution of polyisobutylene (product of BASF, trade name “Oppanol B80”) to carry out crushing treatment (see Japanese Patent No. 3878700). As a result, a solution containing a polyisobutylene squash product having a mass average molecular weight of 55 × 10 ⁴ (in terms of polystyrene) was obtained. To 100 parts of this solution, 0.5 parts of an ultraviolet absorber (Ciba Specialty Chemicals product, trade name “TINUVIN 326”), a light stabilizer (product of the company, trade name “Kimasorb 944”), and a tackifier (Sumitomo) Durez Co., Ltd. product, trade name “Durez 19900”) 0.3 part was blended to prepare an adhesive composition. The composition was applied from above the undercoat layer and dried to form a 10 μm thick polyisobutylene pressure-sensitive adhesive layer. In this way, an adhesive sheet according to Example 1 was produced.

<Example 2>
The resin material used for the preparation of the primer solution was changed to Toyo Kasei Kogyo Co., Ltd., trade name “Hardlen 14-LLB” (chlorinated polyolefin resin). About the other point, it carried out similarly to Example 1, and produced the adhesive sheet which concerns on Example 2. FIG.

<Example 3>
A pressure-sensitive adhesive sheet according to Example 3 was produced in the same manner as Example 1 except that the primer layer was not formed.

<Example 4>
The resin material used for the preparation of the primer solution was changed to Toyo Kasei Kogyo Co., Ltd. product, trade name “Hardlen DX-526” (chlorinated polyolefin resin). About the other point, it carried out similarly to Example 1, and produced the adhesive sheet which concerns on Example 4.

<Example 5>
The resin material used for the preparation of the primer solution was changed to Toyo Kasei Kogyo Co., Ltd., trade name “Hardlen CY-9124” (maleic anhydride-modified chlorinated polyolefin resin). About the other point, it carried out similarly to Example 1, and produced the adhesive sheet which concerns on Example 5. FIG.

<Example 6>
The resin material used for the preparation of the primer solution was changed to Nippon Paper Chemical Co., Ltd. product, trade name “Supercron 851” (maleic anhydride-modified chlorinated polyolefin resin). About the other point, it carried out similarly to Example 1, and produced the adhesive sheet which concerns on Example 6. FIG.

The following evaluation test was done about the adhesive sheet produced in Examples 1-6.
[Normal temperature adhesiveness]
The pressure-sensitive adhesive sheet according to each example was cut into a strip having a width of 25 mm and a length of 150 mm to prepare a test piece. A steel sheet coated with acid epoxy cross-linked acrylic paint (Kansai Paint Co., Ltd., trade name “KINO1210TW”) is degreased with JIS grade 1 hexane, temperature 23 ± 2 ° C., humidity 50 ± 15% RH The test piece was affixed to the coating film in a standard environment adjusted to. The affixing was performed by reciprocating a 2 kg rubber roller specified in JIS Z 0237: 2000 once at a speed of 3 m / min. After pasting, it was kept in the standard environment for 30 minutes (initial adhesive strength) or 48 hours (adhesive strength after pasting), and a low speed peel test and a high speed peel test were performed under the following conditions.
Low-speed peel test: Using an Autograph AG-10G type tensile tester manufactured by Shimadzu Corporation, the peel speed (crosshead speed) is 300 mm / min, the peel angle is 180 °, and the peel length is 100 mm. / 25 mm] was measured. The measurement was performed three times, and the average of these was recorded in Table 1 as a measured value.
High-speed peel test: Using a TE-701 type high-speed peel tester manufactured by Tester Sangyo Co., Ltd., high-speed peel strength [N / 25 mm] is measured under the conditions of a peel speed of 30 m / min, a peel angle of 180 °, and a peel length of 100 mm. did. The measurement was performed three times, and the average of these was recorded in Table 1 as a measured value.

[Adhesion after heating]
The test plate in which the test piece was attached to the coating film in the same manner as in the adhesive test was held for 96 hours in a thermostat adjusted to 80 ± 2 ° C. (product of ESPEC Corporation, model “PH-211”). After taking out from the thermostat and keeping it in a standard environment for 2 hours, the low-speed peel strength [N / 25 mm] and the high-speed peel strength [N / 25 mm] were measured in the same manner as the normal temperature adhesiveness. The measurement was performed three times, and the average of these was recorded in Table 1 as a measured value.

[Adhesive residue]
In order to intentionally create a surface condition in which adhesive residue is likely to occur, the surface of the coating film formed by painting an alkydmelamine paint (product of Kansai Paint Co., Ltd., trade name “TM13RC”) on a 45 cm × 30 cm steel plate (Hitachi Koki Co., Ltd., product name “959-721”) attached with an electric polisher (Makita Co., Ltd. product, model number “PV7001C”), abrasive (Sumitomo 3M product, product name “Hard 5982-1- L ") for 2 minutes. Then, the thing which removed the surface abrasive | polishing agent with the flannel for finishing was used as the to-be-adhered body. The above operation was performed in a standard environment adjusted to a temperature of 23 ± 2 ° C. and a humidity of 50 ± 15% RH.
The pressure-sensitive adhesive sheet according to each example was cut into a strip having a width of 50 mm and a length of 100 mm (corresponding to the coating direction of the pressure-sensitive adhesive composition) to prepare a test piece. The test piece is pressure-bonded to the adherend and held in the standard environment for 1 hour, and then held in a thermostat adjusted to 40 ± 2 ° C. (product of ESPEC Corporation, model “PH-212”) for 96 hours. did. Next, after taking it out in a standard environment and holding it for 4 hours in a low-temperature incubator adjusted to 5 ° C. ± 2 ° C. (Espec Co., Ltd. product, model “WU-200”), the person in charge of the test performs the test from the adherend. The piece was peeled off by hand peeling under conditions of a peeling angle of 90 ° and a peeling speed of about 100 mm / min. The surface of the coated film after peeling was observed visually, and the result was judged as follows.
None: No residue is visually observed.
Existence: Residue is visually observed.

In addition, DSC measurement was performed under the above conditions for the resin material (primer resin) used in the preparation of the primer composition in each example. The obtained data (DSC measurement chart) is shown in FIGS. 2 and 3 for the resin materials used in Examples 1 and 2, respectively, and FIGS. 4 to 6 for the resin materials used in Examples 4 to 6, respectively. In addition, in these FIGS. 2-6, the glass transition temperature (Tg) [degreeC] calculated | required from the DSC measurement result and the temperature [degreeC] of each peak are shown collectively.
The above test results and DSC measurement results are summarized in Table 1.

  As shown in Table 1, in Example 1 and Example 2 in which a chlorinated polyolefin resin having a Tg of 10 ° C. or higher (more specifically 15 ° C. or higher, more specifically 17 ° C. or higher) was used as the primer resin, Example 3 As can be seen from a comparison with (an example in which no primer layer is provided), the adhesive residue resistance was remarkably improved and no increase in adhesive strength was observed even in the above adhesive residue test assuming a polished repair surface and the like. . For example, in the low-speed peel test, an appropriate initial adhesive strength set in consideration of reworkability and coating film protection performance was maintained even after 23 ° C. for 48 hours and further after 80 ° C. for 96 hours. Further, in the high speed peeling test, no increase in adhesive strength was observed even after elapse of 80 ° C. for 96 hours, and it was confirmed that good peeling workability could be maintained even after passing outdoors or in a tropical region. As described above, the pressure-sensitive adhesive sheets according to Examples 1 and 2 have an appropriate adhesive strength with a high balance between adhesion protection and peeling workability, and have excellent anti-residue resistance as well. Met.

  On the other hand, in Examples 4 to 6 using a chlorinated polyolefin resin having a Tg of less than 10 ° C. (more specifically, less than 5 ° C.), the adhesive residue resistance was improved as compared with Example 3, but the heat load was particularly high in the high-speed peel test. The peel strength later (after 80 hours at 80 ° C.) was significantly increased. In these examples, it is surmised that the primer resin diffuses into the pressure-sensitive adhesive layer, and as a result, the stability of the adhesive strength is impaired.

It is sectional drawing which shows typically the example of 1 structure of the coating-film protection sheet which concerns on this invention. 2 is a DSC chart of a chlorinated polyolefin resin used in Example 1. 3 is a DSC chart of a chlorinated polyolefin resin used in Example 2. 6 is a DSC chart of a chlorinated polyolefin resin used in Example 4. 6 is a DSC chart of a chlorinated polyolefin resin used in Example 5. 7 is a DSC chart of a chlorinated polyolefin resin used in Example 6.

Explanation of symbols

1: Substrate (support)
2: Adhesive layer 4: Undercoat layer 10: Coating film protection sheet

Claims (5)

A sheet-like substrate;
A primer layer provided on one side of the substrate, a chlorinated polyolefin system having a glass transition temperature of 10 ° C. or higher determined by DSC measurement wherein the temperature is increased from −10 ° C. to 200 ° C. at a rate of 10 ° C./min. A primer layer mainly composed of a resin;
A polyisobutylene-based pressure-sensitive adhesive layer provided via the primer layer;
A coating film protective sheet.   The sheet according to claim 1, wherein the base material is a polyolefin resin sheet containing a polypropylene resin alone as a resin component, or a polypropylene resin and a polyethylene resin as a resin component.   The sheet according to claim 1 or 2, wherein the chlorinated polyolefin resin is a chlorinated polyolefin resin containing a polyolefin chain graft-modified with an acid. The sheet according to any one of claims 1 to 3, wherein the chlorinated polyolefin resin has a polystyrene-equivalent weight average molecular weight of 3 x 10 ⁴ or more. A method for producing a coating film protective sheet having a configuration in which a polyisobutylene-based pressure-sensitive adhesive layer is provided on one side of a substrate via an undercoat layer, the following steps:
A step of selecting a chlorinated polyolefin resin having a glass transition temperature of 10 ° C. or higher as a resin material for forming the primer layer, which is determined by DSC measurement in which the temperature is increased from −10 ° C. to 200 ° C. at a rate of 10 ° C./min;
Forming a primer layer mainly composed of the chlorinated polyolefin resin on one side of a substrate; and
Forming a polyisobutylene pressure-sensitive adhesive layer on the undercoat layer;
A method for producing a coating film protective sheet.

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