JP2013234321A - Self-adhesive surface protection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a self-adhesive surface protection film showing strong adhesive force to an object to be covered, hardly causing problems of partial elongation, deformation and the like of the film during unwinding the film after storage in a roll state, and showing excellent processing suitability of the film.SOLUTION: In a self-adhesive surface protection film made by laminating an adhesive layer on one surface of a base layer of a polypropylene-based resin and laminating a release layer on the opposite surface by co-extrusion, the resin constituting the adhesive layer contains a styrene-based elastomer and a polyethylene-based resin wherein the styrene-based elastomer is a hydrogenated product of a blocked copolymer of a styrene-based polymer and a butadiene-based polymer or a hydrogenated product of a blocked copolymer having a styrene-based polymer and a random copolymer of styrene and butadiene, and the polyethylene-based resin is an ethylene homopolymer and/or ethylene-α-olefin copolymer.

Description

  The present invention relates to an adhesive film. The adhesive film of the present invention is a member such as a prism sheet used for optical applications, a synthetic resin plate (for example, for building materials), a stainless plate (for example, for building materials), an aluminum plate, a decorative plywood, a steel plate, and a glass plate. , Home appliances, precision machinery, to protect the surface of automobile bodies during manufacturing, to protect articles from being scratched when stacked, stored, transported, transported in the manufacturing process, and articles Can be suitably used for protecting from scratches during secondary processing (for example, bending or pressing).

  Conventionally, adhesive films aimed at protecting the surface of coverings have been used during processing, storage, and transportation of building materials, electricity, electronic products, automobiles, etc. Such adhesive films have good adhesive properties. In addition, after use, each surface must be able to be easily peeled off without being contaminated with an adhesive.

  In recent years, the above-described coverings have been diversified, and there are a large number of coverings having not only smooth covering surfaces but also surface irregularities. Examples of the covering having surface irregularities include a prism type lens portion of a prism sheet used for an optical member. In order to develop a sufficient adhesive force for use on a coated body having surface irregularities such as a prism sheet, the adhesive layer has a high adhesive force so that the adhesive force can be obtained even if the contact area is small. Can be considered.

  In order to increase the adhesive strength of the adhesive layer, it is possible to use a styrene-based elastomer that exhibits high adhesive strength as a main component, but if the adhesive strength of the adhesive layer is increased, the film is stored in a roll state. Then, when the film is subsequently fed out, blocking occurs, causing problems such as partial stretching or deformation of the film.

  As the above-mentioned measures, the base material layer is made of a fluorine-based resin, a silicone-based resin (see, for example, Patent Document 1), an ultra high molecular weight polydimethylsiloxane (for example, see Patent Document 2), a saturated fatty acid bisamide (for example, In addition, there is a possibility that these resins may migrate to the adhesive layer when stored in a roll state, and the adhesive strength is reduced. Concerns such as contamination of the coating cannot be wiped away.

  In addition, although addition of a polyethylene-based resin to the adhesive layer has also been studied (see, for example, Patent Document 4, Patent Document 5, etc.), both store the adhesive force to the prism and the film in a roll state, Thereafter, the above-mentioned problems in feeding the film could not be satisfied together.

JP 2008-81589 A JP 2008-308559 A Japanese Patent No. 4565058 Japanese Patent Application Laid-Open No. 08-73822 Japanese Patent Laid-Open No. 2007-161882

  The problem to be solved by the present invention shows a strong adhesive force to the covering, and can be used for various coverings, while storing the adhesive film in a roll state, and then paying out the film, It is an object of the present invention to provide a self-adhesive surface protective film that is less prone to problems such as partial stretching or deformation of the film and that is excellent in processability of the film.

  As a result of intensive studies, the present inventors have found that the above-described problems can be solved by setting the type and blending ratio of the resin used in the adhesive layer within a predetermined range, and have reached the present invention.

  That is, the present invention is obtained by laminating a pressure-sensitive adhesive layer on one side of a base material layer made of polypropylene resin and a release layer on the opposite side by co-extrusion, and the resin constituting the pressure-sensitive adhesive layer is a styrene-based elastomer, At least a polyethylene resin, and the styrene elastomer is a hydrogenated block copolymer having a styrene polymer block and a butadiene polymer block, or a random mixture of a styrene polymer block, styrene and butadiene. A hydrogenated block copolymer having a copolymer block, wherein the polyethylene resin is an ethylene homopolymer and / or an ethylene-α olefin copolymer, and the styrene elastomer in the adhesive layer The content is 35% by mass or more and 99% by mass or less, and the content of the polyethylene resin is 1% by mass or more, 65 The self-adhesive surface protective film is characterized in that the sum of the ethylene component and the polyethylene resin in the styrene elastomer is 35% by mass or more and less than 70% by mass in the adhesive layer component. Is.

  According to the present invention, the adhesive film has a strong adhesive force to the covering and can be used for various coverings. Thus, it is possible to obtain a self-adhesive surface protective film that is less prone to stretching and deforming and that has excellent processability of the film.

  In this case, it is preferable that the flexural modulus of the ethylene resin used for the adhesive layer is 10 MPa or more and less than 90 MPa.

  In this case, the MFR (190 ° C., 2.16 kgf) of the polyethylene resin in the adhesive layer is preferably 0.5 to 8 g / 10 minutes.

  Furthermore, in this case, it is preferable that the MFR (230 ° C., 2.16 kgf) of the styrene elastomer in the adhesive layer is 0.5 to 8 g / 10 min.

  Furthermore, in this case, it is preferable that the MFR (230 ° C., 2.16 kgf) of the polypropylene resin in the base material layer is 1.0 to 15 g / 10 min.

  The pressure-sensitive adhesive film according to the present invention exhibits a strong adhesive force to the covering and can be used for various coverings. However, when the pressure-sensitive adhesive film is stored in a roll state and then fed out, the film is partially The film has the advantage that the film is not easily stretched or deformed, and is excellent in processability of the film.

Hereinafter, embodiments of the pressure-sensitive adhesive film of the present invention will be described.

(Base material layer)
The pressure-sensitive adhesive film of the present invention requires a base material layer mainly composed of a polypropylene resin. Examples of the polypropylene resin used here include crystalline polypropylene, random copolymer of propylene and a small amount of α-olefin, or block copolymer. In more detail, as a crystalline polypropylene resin, an n-heptane-insoluble isotactic propylene homopolymer used in ordinary extrusion molding or the like, or propylene containing 60% by mass or more of propylene and other α-olefins Mention may be made of copolymers. This propylene homopolymer or a copolymer of propylene and another α-olefin can be used alone or in combination.

  The base material layer preferably contains 60% by mass or more of propylene units, more preferably 70% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more. When the propylene unit is less than 60% by mass, the film loses its sensation and may be difficult to handle. Further, when the propylene unit amount is less than 60% by mass or a polyethylene resin is used, the film becomes flexible and easily stretched, and there is a problem that the film partially stretches or deforms when the film is fed out. It becomes easy to get up.

  Here, n-heptane insolubility is indicative of polypropylene crystallinity and at the same time indicates safety. In the present invention, n-heptane insolubility (at 25 ° C., 60 ° C. according to Ministry of Health and Welfare Notification No. 20 in February 1982). It is a preferred embodiment to use one that is compatible with an elution amount of 150 ppm or less (30 ppm or less when the operating temperature exceeds 100 ° C.)).

Examples of the α-olefin copolymer component constituting the copolymer of propylene and other α-olefins include α-olefins having 2 to 8 carbon atoms such as ethylene, 1-butene, 1-pentene, and 1-hexene. C4- or higher α-olefins such as 4-methyl-1-pentene. Here, the copolymer is preferably a random or block copolymer obtained by polymerizing one or more of the above α-olefins with propylene.
Moreover, the copolymer of a propylene and another alpha olefin can also be used individually or in mixture of 2 or more types.

  The melt flow rate (MFR: 230 ° C., 2.16 kgf) of the polypropylene resin used is preferably in the range of 1.0 to 15 g / 10 minutes, more preferably in the range of 2.0 to 10.0 g / 10 minutes.

  Furthermore, the waste film produced when the film obtained in the present invention is processed into a product can be re-granulated as a recovered raw material and added to the base material layer. By using the recovered raw material, the production cost can be reduced.

(Adhesive layer)
The pressure-sensitive adhesive layer according to the present invention needs to contain a styrene elastomer in order to develop a high pressure-sensitive adhesive force. Moreover, in order to express the adhesive force and the drawing property of the film from the roll state, the adhesive layer needs to contain a polyethylene resin. By adding a polyethylene-based resin, it is possible to reduce the peeling force from the pressure-sensitive adhesive side to the release surface. Moreover, tackifying resin other than polyethylene resin, a softening agent, polystyrene, etc. can also be mixed with an adhesion layer as needed for control of adhesive force.

  The amount of the styrene-based elastomer in the adhesive layer is 35% by mass or more and 99% by mass or less with respect to 100% by mass of the adhesive layer component in order to express high adhesive force and roll-out property from the roll state. It is necessary. If it is less than 35% by mass, the adhesive strength is lowered and it is difficult to obtain the required adhesive strength. The amount of styrenic elastomer in the adhesive layer is preferably in the range of 38% by mass to 95% by mass. More preferably, it is the range of 40 mass% or more and 90 mass% or less.

  Examples of the styrene elastomer include hydrogenated ABA block polymers such as styrene-butadiene-styrene copolymers, hydrogenated AB block polymers such as styrene-butadiene copolymers, styrene- Examples thereof include a hydrogenated product of a styrene random copolymer such as butadiene rubber. These hydrogenated bodies may be partially hydrogenated bodies or fully hydrogenated bodies.

  The styrene component in the styrene-based elastomer is desirably 5% by mass or more and 40% by mass or less. If it is less than 5% by mass, granulation at the time of producing the resin becomes difficult, and if it exceeds 40% by mass, the adhesive strength is lowered, and it may be difficult to obtain the required adhesive strength. The styrene component in the styrene-based elastomer is preferably in the range of 8% by mass to 35% by mass, and more preferably in the range of 10% by mass to 30% by mass.

  On the other hand, the ethylene component in the styrene elastomer is desirably 15% by mass or more and 70% by mass or less. The ethylene component in the styrene-based elastomer has an effect of increasing the compatibility with the polyethylene-based resin, and also has an effect of increasing the feeding property of the film from the roll state. Therefore, it is considered that when the amount of ethylene component is large, the effect of improving the feedability is likely to increase. In addition, it is thought that the ethylene component in a styrene-type elastomer has contributed greatly also to expression of adhesive force, and when the amount of ethylene components exceeds 70 mass%, there exists a possibility that the adhesive force of an adhesion layer may become high too much.

  Moreover, it is preferable that a butylene component exists in a styrene-type elastomer. When the butylene component is 50% by mass or more, when a polyethylene resin is added, the adhesive force tends to be difficult to decrease, which is preferable.

  The melt flow rate (MFR: 230 ° C., 2.16 kgf) of the styrene elastomer to be used is preferably in the range of 0.5 to 8 g / 10 minutes in terms of film forming properties, and is preferably 2.0 to 7.0 g / 10 minutes. The range of is more preferable.

  The amount of the polyethylene-based resin in the adhesive layer needs to be 1% by mass or more and 65% by mass or less in order to express high adhesive force and roll out of the film from the roll state. When the amount of the polyethylene resin in the adhesive layer exceeds 65% by mass, the adhesive strength is lowered, and it becomes difficult to obtain the required adhesive strength. The amount of the polyethylene resin in the adhesive layer is preferably in the range of 3% by mass to 60% by mass.

Examples of the polyethylene resin include low density polyethylene and a copolymer of ethylene and α-olefin. Among these, low-density polyethylene, in particular, linear low-density polyethylene called LLDPE and ultra-low-density polyethylene called VLDPE are preferable because they can improve the film feeding property while maintaining adhesive strength. These are those in which a short chain branch is introduced into an ethylene chain by copolymerizing an α-olefin, and flexibility can be imparted to the polyethylene-based resin depending on the type and copolymerization amount of the α-olefin.
Examples of the α-olefin include 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene and the like.

  In the pressure-sensitive adhesive layer according to the present invention, the sum of the ethylene component and the ethylene resin in the styrene-based elastomer is in the range of 35% by mass or more and less than 70% by mass in the pressure-sensitive adhesive layer component. When the sum of the ethylene component and the ethylene-based resin is 70% by mass or more in the adhesive layer component, the adhesive strength is lowered and sufficient adhesive strength cannot be obtained. If the sum of the ethylene component and the ethylene-based resin is less than 35% by mass in the adhesive layer component, the peeling force of the film adhesive layer on the release layer is increased. Preferably, the sum of the ethylene component and the ethylene-based resin is 40% by mass or more and less than 70% by mass in the adhesive layer component. More preferably, the sum of the ethylene component and the ethylene-based resin is 45% by mass or more and 65% by mass or less in the adhesive layer component. Particularly preferably, the sum of the ethylene component and the ethylene-based resin is 45% by mass or more and 63% by mass or less in the adhesive layer component.

  The flexural modulus of the polyethylene resin is desirably 10 MPa or more and less than 90 MPa. When the pressure is less than 10 MPa, the roll-out property of the film from the roll state is lowered, and when it is 90 MPa or more, the pressure-sensitive adhesive layer becomes hard and the pressure-sensitive adhesive force tends to be lowered. The flexural modulus of the polyethylene resin is preferably in the range of 15 MPa to 80 MPa, more preferably in the range of 20 MPa to 70 MPa.

  In order to make the flexural modulus within the above range, one measure is to adjust the ethylene component in the polyethylene resin. From such a viewpoint, the ethylene component in the polyethylene resin is preferably 70% by mass or more. The ethylene component of the polyethylene resin is more preferably 75% by mass or more, and still more preferably 80% by mass or more. Further, the ethylene content of the polyethylene resin is preferably 98% by mass or less, more preferably 96% by mass or less, still more preferably 95% by mass or less, and particularly preferably 94% by mass or less. When the ethylene component in the polyethylene-based resin is less than 70% by mass, the effect of improving the drawability of the film from the roll state tends to be small. Examples of the polyethylene resin in which the ethylene component in the polyethylene resin is 70% by mass or more include CX3007 and VL100 manufactured by Sumitomo Chemical Co., Ltd.

  The density of the polyethylene resin is preferably 850 kg / m3 to 920 kg / m3, more preferably 860 kg / m3 to 910 kg / m3, and particularly preferably 870 kg / m3 to 908 kg / m3. Preferably, it is 880 kg / m3 to 906 kg / m3. By making it in the above range, it becomes easy to achieve both good adhesiveness and feeding property.

  The melt flow rate (MFR: 190 ° C., 2.16 kgf) of the polyethylene-based resin used is preferably in the range of 0.5 g / 10 min to 8 g / 10 min, and 0.8 g / 10 min to 7.0 g / 10 min. The range of is more preferable. By making it the said range, it becomes easy to perform the film-forming which made the thickness of each layer uniform.

  The adhesive layer may contain a polyolefin resin other than the polyethylene resin, and the type thereof is not particularly limited, and examples thereof include crystalline polypropylene, copolymerization of propylene and a small amount of α-olefin, and the like. Since these resins generally tend to decrease the adhesive strength even if they are blended in a small amount, it is preferable to blend them in a proportion of 1% by mass or more and 20% by mass or less.

  Examples of the tackifying resin include aliphatic hydrocarbon resins, aromatic hydrocarbon resins, terpene resins, coumarone-indene resins, styrene resins, rosin resins, and the like. The molecular weight of the tackifying resin is not particularly limited and can be set appropriately. However, if the molecular weight is small, there is a risk of causing material transfer from the adhesive layer to the coated body or heavy peeling, while the molecular weight is large. If it becomes, there exists a tendency for the improvement effect of adhesive force to become scarce. Therefore, the number average molecular weight of the tackifier resin is preferably about 1,000 to 100,000. The number average molecular weight can be measured by gel permeation chromatography (standard substance: polystyrene) or the like.

  The compounding amount of the tackifying resin in the adhesive layer is preferably in the range of 5% by mass to 20% by mass with respect to 100% by mass of the adhesive layer component. If the compounding amount of the tackifying resin exceeds 20% by mass, the molecular weight of the tackifying resin is low, so the melt viscosity becomes extremely low, and a polypropylene resin is mainly used when coextrusion film formation using a T die or the like is performed. Not only is it difficult to laminate the base material layer as a component, but also the adhesive layer becomes sticky, and the roll-out property of the film from the roll state tends to be difficult to improve. Moreover, even if it mix | blends that the compounding quantity of tackifying resin in an adhesion layer is less than 5 mass%, it is hard to contribute to the adhesive force change of an adhesion layer. Therefore, the blending amount of the tackifying resin is preferably 6% by mass or more and 20% by mass or less. More preferably, it is the range of 6 mass% or more and 15 mass% or less.

  When the melt viscosity tends to decrease due to the addition of the tackifying resin in the adhesive layer, by adding about 1% by mass to 15% by mass of a polystyrene resin to the adhesive layer, the base layer and the adhesive layer are added. The difference in melt viscosity can be improved, and lamination can be facilitated. The amount of the polystyrene resin blended is preferably 3% by mass or more and 12% by mass or less, more preferably 5% by mass or more and 10% by mass or less.

  Examples of the softening agent include low molecular weight diene polymers, polyisobutylene, hydrogenated polyisoprene, hydrogenated polybutadiene, derivatives thereof, and polybutene. The molecular weight of the softening agent is not particularly limited and can be set appropriately.However, if the molecular weight is small, there is a risk of causing material transfer from the adhesive layer to the coated body or heavy peeling, while the molecular weight is large. There is a tendency that the effect of improving the adhesion is poor. Therefore, the number average molecular weight of the softener is preferably about 1,000 to 100,000. The number average molecular weight can be measured by the same method as in the case of the tackifier resin.

  Further, the tackifying resin and softening agent used in the adhesive layer are liquids or powders depending on the type, and there are things that contaminate the extruder during extrusion. Such a problem can be improved by using a tackifier resin or a softener in a master batch with a polyethylene resin or a polyolefin resin. Therefore, it is preferable to use the tackifier resin and the softening agent in a master batch with a polyethylene resin or a polyolefin resin.

  The adhesive strength of the pressure-sensitive adhesive film (pressure-sensitive adhesive layer) of the present invention is preferably in the range of 200 cN / 25 mm to 1000 cN / 25 mm with respect to the acrylic plate at 23 ° C. in consideration of use in various coverings. When the adhesive strength is less than 200 cN / 25 mm, turning or the like occurs when protecting depending on the covering, and the function as a protective film cannot be carried. On the other hand, when the adhesive strength exceeds 1000 cN / 25 mm, there is a possibility that the film cannot be smoothly peeled when the film is peeled from the covering.

  Further, at 23 ° C., the range of 2 cN / 25 mm to 20 cN / 25 mm with respect to the prism sheet is preferable in consideration of use. When the adhesive strength is less than 2 cN / 25 mm, turning or the like occurs when protecting, and the function as a protective film cannot be carried. On the other hand, when the adhesive strength exceeds 20 cN / 25 mm, there is a possibility that the film cannot be smoothly peeled when the film is peeled off. The adhesive strength can be appropriately set by changing the resin composition, thickness, etc. of the adhesive layer.

  The pressure-sensitive adhesive layer according to the present invention may contain known additives as necessary. For example, a lubricant, an antiblocking agent, a heat stabilizer, an antioxidant, an antistatic agent, a light resistance agent, an impact resistance improvement agent and the like may be contained. However, these components have a relatively low molecular weight, and may bleed out to the surface of the adhesive layer to reduce the adhesive strength of the adhesive layer. Therefore, when an additive is used, it is preferable that the amount of low molecular weight substances on the surface of the adhesive layer is less than 1 mg / m2.

  The measurement of the low molecular weight substance on the surface of the adhesive layer was performed according to the following procedure. After washing the surface of the adhesive layer with an organic solvent that does not erode the resin constituting the adhesive layer such as ethanol, the organic solvent was removed from the cleaning liquid with an evaporator, and the residue was weighed and the numerical value obtained by washing was washed. It was obtained by dividing by the surface area of the adhesive layer surface. If the residue is present at 1 mg / m 2 or more, foreign matter will be present between the surface of the adhesive layer and the surface of the cover, reducing the contact area with the cover and reducing the van der Waals force. It is not preferable because the power is reduced. When adding additives, select additives such as polymer type, or study the amount and method of addition, so that there is no migration or transfer of low molecular weight substances (foreign substances) to the adhesive layer. It is necessary to.

(Release layer)
The pressure-sensitive adhesive film of the present invention has a release layer on the surface opposite to the pressure-sensitive adhesive layer laminated on one side of the base material layer. Thereby, even if it sticks adhesive films, it can suppress that blocking of adhesive films arises. By providing a release layer, especially when the adhesive film is stored in a roll state, and when the film is subsequently fed out, it is difficult to cause problems such as partial stretching or deformation of the film, and excellent in workability. It can be. In order to prevent blocking of the adhesive films even when the adhesive films are stacked, it is effective to form surface irregularities on the release layer to reduce the contact area with the adhesive layer.

  The release layer preferably has a polypropylene resin as a main component (about 50% by mass or more). Specific examples of the polypropylene resin include propylene-ethylene block copolymers.

  In order to form surface irregularities as described above in the release layer, it is effective to mix an incompatible resin with a polypropylene resin. By doing so, a layer whose surface is rough like a mat can be formed. In addition, when using a propylene-ethylene block copolymer as a polypropylene resin, the same effect can be expected without using an incompatible resin for the polypropylene resin. Of course, it is also possible to add a resin incompatible with the polypropylene resin to the propylene-ethylene block copolymer.

  As the resin incompatible with the polypropylene resin, an α-olefin (co) polymer having 4 or more carbon atoms such as low density polyethylene and 4-methylpentene-1 (co) polymer is preferably used. In addition, linear low density polyethylene, high density polyethylene, copolymers of ethylene and a small amount of α-olefin, copolymers of ethylene and vinyl acetate, polystyrene, polyester resins, polyamide resins, etc. It is done. In particular, when 4-methylpentene-1 (co) polymer is used, not only the surface of the release layer is roughened but also the surface free energy on the film surface is lowered, thereby further improving the peelability. Can be expected.

  In view of the resin composition of the pressure-sensitive adhesive layer of the present invention, it is preferable that the three-dimensional average surface roughness SRa of the release layer surface is 0.10 μm or more and 0.50 μm or less. By doing so, blocking resistance and the protection performance of a covering can be improved. When the surface roughness of the release layer is lower than 0.10 μm, the film feedability when the film is in roll form may be deteriorated. When the surface roughness of the release layer is higher than 0.50 μm, the surface irregularities of the release layer may be transferred to the surface of the adhesive layer, and the adhesive force may be significantly reduced. At this time, the surface unevenness of the release layer is more preferably a surface having an average surface roughness SRa of 0.25 μm or more and 0.45 μm or less.

  The three-dimensional average surface roughness SRa of the release layer surface means the average roughness at the center plane when the surface roughness curve is approximated by a sine curve, and can be measured by a surface roughness measuring device or the like.

(Self-adhesive surface protective film)
The self-adhesive surface protective film of this invention is comprised from each layer of the base material layer containing the said resin component, the adhesion layer, and a mold release layer. The thickness of the self-adhesive surface protective film of the present invention is preferably 10 μm or more and 150 μm or less, more preferably 15 μm or more and 120 μm or less, and further preferably 20 μm or more and 100 μm or less. If the total thickness of the film is too thin, it may be inferior in handling, and if it is too thick, the rigidity becomes high and handling properties are inferior, and the film may be disadvantageous in terms of cost.

  The thickness of the base material layer of the present invention is preferably 5 μm or more and less than 100 μm, more preferably 10 μm or more and 75 μm or less, and further preferably 15 μm or more and 55 μm or less. When the thickness of the base material layer is less than 5 μm, there is a problem that the waist feeling is weak, wrinkles etc. are easily formed when pasted to a covering as a protective film, and sufficient adhesive strength cannot be obtained. If it is above, the film is disadvantageous in terms of cost.

  The thickness of the pressure-sensitive adhesive layer of the present invention is preferably 1 μm or more and less than 30 μm. When the thickness of the adhesive layer is less than 1 μm, stable film formation by coextrusion becomes difficult, and when it is 30 μm or more, a film is disadvantageous in terms of cost. At this time, when increasing the adhesive force, it is preferable to increase the thickness of the adhesive layer in consideration of its viscosity. Increasing the thickness of the adhesive layer tends to increase the contact area with the covering. The thickness of the adhesive layer is preferably 2 μm or more and 20 μm or less, more preferably 3 μm or more and 15 μm or less, and particularly preferably 4 μm or more and 8 μm or less.

  The thickness of the release layer of the present invention is preferably 1 μm or more and less than 30 μm. When the thickness of the release layer is less than 1 μm, stable film formation by coextrusion becomes difficult, and when it is 30 μm or more, a film is disadvantageous in terms of cost. The thickness of the release layer is preferably 2 μm or more and 20 μm or less, and more preferably 3 μm or more and 15 μm or less.

  The peeling force of the pressure-sensitive adhesive surface of the pressure-sensitive adhesive film of the present application with respect to the release surface is preferably within a range of 250 cN / 40 mm or less at 23 ° C. from the viewpoint of the film payout property when the pressure-sensitive adhesive film is in roll form. If the peeling force exceeds 250 cN / 40 mm, problems such as partial stretching or deformation of the film occur when the film is fed out when the adhesive film is rolled. More preferably, it is 200 cN / 40 mm or less. In addition, the lower limit of the peeling force with respect to the mold release surface of the pressure-sensitive adhesive film is about 1 cN / 40 mm, more preferably about 5 cN / 40 mm, as a practical value.

  The self-adhesive surface protective film of the present invention is composed of a substrate layer containing the above resin component, an adhesive layer, and a release layer, and the resin constituting each layer is, for example, a single-screw or biaxial extruder. It is obtained by being fed into a feed block type or multi-manifold type T-die while being melted and laminated and extruded with three layers (base material layer, adhesive layer, release layer) or more. The temperature of the extruder of each layer may be adjusted as appropriate in consideration of the molding temperature of the components used in each layer in order to bring each layer into a molten state, for example, adjusted in the range of 200 ° C to 260 ° C. Also good. The temperature of the T die may be the same as the above temperature. The take-up speed from the T die to the casting roll may be a speed at which each layer has a suitable thickness, and is, for example, 10 m / min to 200 m / min, preferably 10 m / min to 100 m / min.

  The adhesive film of the present invention is preferably in the form of a roll in terms of handling. The upper limit of the width and the winding length of the film roll is not particularly limited, but from the viewpoint of ease of handling, the width is generally 1.5 m or less, and the winding length is preferably 5000 m or less when the film thickness is 40 μm. Moreover, as a winding core, a plastic core and metal cores, such as 3 inches, 6 inches, and 8 inches, can usually be used. Moreover, it is preferable that it is a film roll wound up by the dimension of length 200m or more and width 450mm or more from the suitability of a process.

  The adhesive film of the present invention is a member such as a prism sheet used for optical applications, a synthetic resin plate (for example, for building materials), a stainless plate (for example, for building materials), an aluminum plate, a decorative plywood, a steel plate, and a glass plate. , Home appliances, precision machinery, to protect the surface of automobile bodies during manufacturing, to protect articles from being scratched when stacked, stored, transported, transported in the manufacturing process, and articles Can be used for protecting from scratches during secondary processing (for example, bending or pressing).

  This application claims the benefit of priority based on Japanese Patent Application No. 2012-89184 filed on Apr. 10, 2012. The entire contents of the specification of Japanese Patent Application No. 2012-89184 filed on April 10, 2012 are incorporated herein by reference.

  The following examples further illustrate the invention. However, the present invention is not limited to the following examples without departing from the gist thereof. In addition, the evaluation method of the physical property in a following example and a comparative example is as follows.

(1) Evaluation of adhesiveness It measured by the following method based on the JIS-Z-0237 (2000) adhesive tape * adhesive sheet test method.
As the covering, acrylic plate (Mitsubishi Rayon Co., Ltd .: Acrylite (registered trademark) 3 mm thick) 50 mm × 150 mm and prism sheet (the lens part is made of a triangular prism, the height of the triangular prism is 25 μm, the width of the triangular prism is 50 μm) ) 50 mm × 150 mm were prepared. As a test piece, a test piece having a size of 150 mm in the winding direction at the time of film production and 25 mm in a direction perpendicular thereto was cut out.

  Using a rubber roll having a mass of 2000 g (with a roller surface spring hardness of 80 Hs and a thickness of 6 mm and having a width of 45 mm and a diameter (including the rubber layer) of 95 mm), the covering and the test piece are 5 mm. The pressure was reciprocated once at a speed of / sec. After crimping, what was allowed to stand for 30 minutes in an environment of a temperature of 23 ° C. and a relative humidity of 65% was used with “Autograph (registered trademark)” (AGS-J) manufactured by Shimadzu Corporation at a speed of 300 mm / min. The resistance value when peeled by 180 degrees was defined as the adhesive strength [cN / 25 mm]. 180 degree peeling means holding the peeling angle between the acrylic plate and the film at the time of measuring the resistance value at the time of peeling at 180 degrees.

  At the time of measurement, a polyester sheet having a thickness of 190 μm and a size of 25 mm × 170 mm is prepared as a grip margin for the measurement sample, and the width of the paste margin is 15 mm at the end of the measurement sample on which the test piece and the acrylic plate are pressure bonded. The polyester sheet was affixed with cellophane tape and used as a grip allowance for measurement. A schematic diagram of the measurement sample is shown in FIG. The measurement was carried out for three samples prepared from the films produced in the examples and comparative examples, and the average value was taken as the adhesive strength of the samples. In the case of the prism sheet, the measurement was performed in the same manner.

(2) Evaluation of peeling force Acrylic board (Mitsubishi Rayon Co., Ltd .: Acrylite (registered trademark) 3 mm thickness) 50 mm × 150 mm was pasted with a double-sided adhesive tape (manufactured by Nitto Denko Corporation). A test piece of 150 mm (winding direction at the time of film production) × 50 mm (direction perpendicular to the winding direction at the time of film production) was attached so that the adhesive surface of the test piece came to the other surface.

  As a new test piece, a test piece having a length of 150 mm in the winding direction at the time of film production and a length of 40 mm in the direction perpendicular thereto is cut out and pasted to the adhesive surface and the acrylic plate through a double-sided adhesive tape. After the release surfaces of the test pieces were superposed, a rubber roll having a mass of 2000 g (with a roller surface spring hardness of 80 Hs and a 6 mm thick rubber layer, 45 mm width and 95 mm diameter (including rubber layer)) ), The mold release surface and the test piece were reciprocated once at a speed of 5 mm / second and pressure bonded. After crimping, a load of 60 kg is applied to a total area of 4000 mm2 of 100 mm in the winding direction and 40 mm in the direction perpendicular to it, left to stand in an environment of a temperature of 40 ° C. and a relative humidity of 65% for 24 hours, and then cooled to 23 ° C. Using “Autograph (registered trademark)” (AGS-J) manufactured by Shimadzu Corporation, the resistance value when peeled 180 degrees at a speed of 300 mm / min was defined as the peel force [cN / 40 mm].

  When measuring, prepare a polyester sheet with a thickness of 190 μm and a size of 40 mm × 170 mm as a grip for the measurement sample, and paste it on the end of a 150 mm × 40 mm test piece with a cellophane tape with a width of 15 mm. It was set as a grab allowance. The measurement was performed three times for one sample, and the average value was taken as the peel strength of the sample.

(3) Rollability from roll After obtaining a wound body of 550 mm width and 500 m winding with a slit, it was stored in a roll state for 7 days in a light-shielding environment at a temperature of 23 ° C. and a humidity of 75%. Immediately after rewinding the film roll after storage to another plastic core (diameter 9 cm) by 300 m, the film end was gripped by hand and pulled back by 3 m. When the film was rewound, it was visually confirmed whether or not the film had partial elongation or deformation. The case where there was no partial elongation or deformation was rated as ◯ (good), and the case where there was partial expansion or deformation as x (bad).

(4) MFR measurement of resin It measured based on JIS-K7210.

(5) Measurement of flexural modulus of resin The measurement was performed in accordance with ASTM D747-70.

(6) Measurement of ethylene component in styrene-based elastomer About 330 mg of a resin sample was dissolved in deuterated chloroform, and 13C-NMR (manufactured by BRUKER, AVANCE500) was measured. From the obtained measurement results, the amount of ethylene component in the styrene-based elastomer was identified.

[Example 1]
(Preparation of base material layer)
100% by mass of a homopolypropylene resin (manufactured by Sumitomo Chemical Co., Ltd .: FLX80E4, 230 ° C. MFR: 7.5 g / 10 min) was melt-extruded at 240 ° C. with a 90 mmφ single screw extruder to obtain a base material layer.

(Preparation of adhesive layer)
Styrene elastomer (hydrogenated block copolymer of styrene and butadiene, manufactured by Asahi Kasei Chemicals: Tuftec (registered trademark) H1221, styrene component ratio 12% by mass, ethylene component ratio 18% by mass, 230 ° C. MFR: 4.5 g / 10 min) 40% by mass, ethylene-α-olefin copolymer (Sumitomo Chemical Co., Ltd .: CX3007, 190 ° C. MFR: 3.7 g / 10 min, elastic modulus: 26 MPa) and 50% by mass and petroleum resin (Arakawa Chemical: Alcon (registered) (Trademark) P125) 10% by mass was melt-extruded at 210 ° C. with a 45 mmφ single screw extruder to form an adhesive layer.

(Production of release layer)
90% by mass of propylene-ethylene block copolymer (manufactured by Nippon Polypropylene: BC3HF) and 10% by mass of low density polyethylene resin (manufactured by Ube Industries: R300) were melt extruded at 230 ° C. with a 65 mmφ single-screw extruder to form a release layer. .

(Production of film)
Lamination extrusion is performed in a 245 ° C three-layer T die (feed block type, lip width 850 mm, lip gap 1 mm) with the base material layer, adhesive layer, and release layer melted in each extruder. It was. The extruded film is taken to a casting roll at a temperature of 30 ° C. at a rate of 20 m / min, cooled and solidified, and the substrate layer thickness is 28 μm, the adhesive layer thickness is 6 μm, the release layer thickness is 6 μm, the film width is 600 mm, and the film length. A three-kind three-layer unstretched film having a length of 1100 m was obtained. Furthermore, this film was slit at a speed of 50 m / min while applying a contact pressure of 50 N to the film width by a rubber roll with a take-up tension of 40 N, whereby an unstretched film having a film width of 550 mm and a film length of 500 m was obtained. Obtained.

[Example 2]
The base material layer and the release layer were the same as in Example 1, but the adhesive layer was changed to the following content, and a three-kind three-layer unstretched film was obtained by the same production method as in Example 1.
(Preparation of adhesive layer)
Styrene elastomer (Asahi Kasei Chemicals: Tuftec (registered trademark) H1221, styrene component ratio 12% by mass, ethylene component ratio 18% by mass, 230 ° C. MFR: 4.5 g / 10 min) 60% by mass and ethylene-α olefin copolymer 40% by mass (Sumitomo Chemical Co., Ltd .: CX3007, 190 ° C. MFR: 3.7 g / 10 min, elastic modulus: 26 MPa) was melt-extruded at 210 ° C. with a 45 mmφ single screw extruder to obtain an adhesive layer.

[Example 3]
The base material layer and the release layer were the same as in Example 1, but the adhesive layer was changed to the following content, and a three-kind three-layer unstretched film was obtained by the same production method as in Example 1.
(Preparation of adhesive layer)
Styrene elastomer (hydrogenated block copolymer of styrene and butadiene, manufactured by Asahi Kasei Chemicals: Tuftec (registered trademark) H1221, styrene component ratio 12% by mass, ethylene component ratio 18% by mass, 230 ° C. MFR: 4.5 g / 10 min) 40% by mass and ethylene-α-olefin copolymer (Sumitomo Chemical Co., Ltd .: VL100, 190 ° C. MFR: 0.8 g / 10 min, elastic modulus: 64 MPa) 50% by mass and petroleum resin (Arakawa Chemical: Alcon (registered) (Trademark) P125) 10% by mass was melt-extruded at 210 ° C. with a 40 mmφ single-screw extruder to obtain an adhesive layer.

[Example 4]
The base material layer and the release layer were the same as in Example 1, but the adhesive layer was changed to the following content, and a three-kind three-layer unstretched film was obtained by the same production method as in Example 1.
(Preparation of adhesive layer)
Styrene elastomer (manufactured by Asahi Kasei Chemicals: Tuftec (registered trademark) H1041, styrene component ratio 30% by mass, ethylene component ratio 49% by mass, 230 ° C. MFR: 5.0 g / 10 min) 85% by mass and ethylene-α olefin copolymer (Sumitomo Chemical Co., Ltd .: CX3007, 190 ° C. MFR: 0.8 g / 10 min, elastic modulus: 26 MPa) 5 mass% and petroleum resin (Arakawa Chemical: Alcon (registered trademark) P125) 10 mass% are 40 mmφ single screw extruder. Was subjected to melt extrusion at 210 ° C. to form an adhesive layer.

[Example 5]
The substrate layer and the release layer were the same as in Example 1, except that the adhesive layer was changed to the following contents, the substrate layer thickness was 26 μm, the adhesive layer thickness was 8 μm, and the release layer thickness was 6 μm. A three-kind three-layer unstretched film was obtained by the same production method as in No. 1.

(Preparation of adhesive layer)
Styrene elastomer (Asahi Kasei Chemicals: Tuftec (registered trademark) H1221, styrene component ratio 12% by mass, ethylene component ratio 18% by mass, 230 ° C. MFR: 4.5 g / 10 min) 60% by mass and ethylene-α olefin copolymer 40% by mass (Sumitomo Chemical Co., Ltd .: CX3007, 190 ° C. MFR: 3.7 g / 10 min, elastic modulus: 26 MPa) was melt-extruded at 210 ° C. with a 45 mmφ single screw extruder to obtain an adhesive layer.

[Example 6]
The substrate layer and the release layer were the same as in Example 1, except that the adhesive layer was changed to the following contents, the substrate layer thickness was 30 μm, the adhesive layer thickness was 4 μm, and the release layer thickness was 6 μm. A three-kind three-layer unstretched film was obtained by the same production method as in No. 1.

(Preparation of adhesive layer)
Styrene elastomer (Asahi Kasei Chemicals: Tuftec (registered trademark) H1221, styrene component ratio 12% by mass, ethylene component ratio 18% by mass, 230 ° C. MFR: 4.5 g / 10 min) 40% by mass and ethylene-α olefin copolymer (Sumitomo Chemical Co., Ltd .: CX3007, 190 ° C. MFR: 3.7 g / 10 min, elastic modulus: 26 MPa) 55% by mass and petroleum resin (Arakawa Chemical: Alcon (registered trademark) P125) 5% by mass are 45 mmφ single-screw extruder. Was subjected to melt extrusion at 210 ° C. to form an adhesive layer.

[Comparative Example 1]
The base material layer and the release layer were the same as in Example 1, but the adhesive layer was changed to the following content, and a three-kind three-layer unstretched film was obtained by the same production method as in Example 1.
(Preparation of adhesive layer)
70% by mass of an styrene-based elastomer (Asahi Kasei Chemicals: Tuftec (registered trademark) H1221, styrene component ratio 12% by mass, ethylene component ratio 18% by mass, 230 ° C. MFR: 4.5 g / 10 min), and ethylene-α-olefin copolymer (Sumitomo Chemical Co., Ltd .: CX3007, 190 ° C. MFR: 3.7 g / 10 min, elastic modulus: 26 MPa) 20% by mass and petroleum resin (Arakawa Chemical: Alcon (registered trademark) P125) 10% by mass are 40 mmφ single-screw extruder. Was subjected to melt extrusion at 210 ° C. to form an adhesive layer.

[Comparative Example 2]
The base material layer and the release layer were the same as in Example 1, but the adhesive layer was changed to the following content, and a three-kind three-layer unstretched film was obtained by the same production method as in Example 1.
(Preparation of adhesive layer)
70% by mass of an styrene-based elastomer (Asahi Kasei Chemicals: Tuftec (registered trademark) H1221, styrene component ratio 12% by mass, ethylene component ratio 18% by mass, 230 ° C. MFR: 4.5 g / 10 min) and ethylene-α-olefin copolymer ( Sumitomo Chemical Co., Ltd .: VL100, 190 ° C. MFR: 0.8 g / 10 min, elastic modulus: 64 MPa 20 mass% and petroleum resin (Arakawa Chemical: Alcon (registered trademark) P125) 10 mass% in a 40 mmφ single screw extruder. Then, it was melt extruded at 210 ° C. to obtain an adhesive layer.

[Comparative Example 3]
Styrene elastomer (Asahi Kasei Chemicals: Tuftec (registered trademark) H1221, styrene component ratio 12% by mass, ethylene component ratio 18% by mass, 230 ° C. MFR: 4.5 g / 10 min) 20% by mass and ethylene-α olefin copolymer (Sumitomo Chemical Co., Ltd .: CX3007, 190 ° C. MFR: 3.7 g / 10 min, elastic modulus: 26 MPa) 70% by mass and petroleum resin (Arakawa Chemical Co., Ltd .: Alcon (registered trademark) P125) 10% by mass 40 mmφ single screw extruder Was subjected to melt extrusion at 210 ° C. to form an adhesive layer.

[Comparative Example 4]
The base material layer and the release layer were the same as in Example 1, but the adhesive layer was changed to the following content, and a three-kind three-layer unstretched film was obtained by the same production method as in Example 1.
(Preparation of adhesive layer)
Styrene elastomer (Asahi Kasei Chemicals: Tuftec (registered trademark) H1221, styrene component ratio 12% by mass, ethylene component ratio 18% by mass, 230 ° C. MFR: 4.5 g / 10 min) 40% by mass and homopolypropylene (manufactured by Sumitomo Chemical Co., Ltd.) : FLX80E4, 190 ° C. MFR: 7.5 g / 10 min) 50% by mass and petroleum resin (Arakawa Chemical: Alcon (registered trademark) P125) 10% by mass are melt-extruded at 210 ° C. with a 40 mmφ single-screw extruder and adhered. Layered.

  The results are shown in Tables 1 and 2.

  As is clear from Table 2, the films obtained in Examples 1 to 6 had practically sufficient adhesive strength when used as a protective film, and had good peelability when the film was fed from a roll. It was.

  On the other hand, the films obtained in Comparative Examples 1 and 2 were not necessarily good in peelability when the film was drawn from the roll. The films obtained in Comparative Examples 3 and 4 could not be said to have sufficient adhesion to the covering. Thus, all the films obtained in the comparative examples were inferior in quality and low in practicality.

It is a schematic diagram of a measurement sample.

Claims (5)

The adhesive layer is laminated on one side of the base material layer made of polypropylene resin, and the release layer is laminated on the opposite side by coextrusion,
The resin constituting the adhesive layer includes at least a styrene elastomer and a polyethylene resin,
The styrene elastomer has a hydrogenated block copolymer having a styrene polymer block and a butadiene polymer block, or a random copolymer block of a styrene polymer block and styrene and butadiene. It is a hydrogenated block copolymer, and the polyethylene resin is an ethylene homopolymer and / or an ethylene-α olefin copolymer,
The content of the styrene elastomer in the adhesive layer is 35% by mass or more and 99% by mass or less, the content of the polyethylene resin is 1% by mass or more and 65% by mass or less, and the ethylene component in the styrene elastomer A self-adhesive surface protective film characterized in that the sum of the content with a polyethylene resin is 35% by mass or more and less than 70% by mass in the adhesive layer component.   The self-adhesive polypropylene film according to claim 1, wherein the flexural modulus of the polyethylene resin used for the adhesive layer is 10 MPa or more and less than 90 MPa.   The self-adhesive polypropylene film according to claim 1 or 2, wherein the polyethylene resin in the adhesive layer has an MFR (190 ° C, 2.16 kgf) of 0.5 to 8 g / 10 min.   The self-adhesive polypropylene film according to any one of claims 1 to 3, wherein the MFR (230 ° C, 2.16 kgf) of the styrene-based elastomer in the adhesive layer is 0.5 to 8 g / 10 minutes.   The self-adhesive polypropylene film according to any one of claims 1 to 4, wherein the polypropylene resin in the base material layer has an MFR (230 ° C, 2.16 kgf) of 1.0 to 15 g / 10 min.