TW201325899A - Polyolefin based film - Google Patents

Abstract

The present invention obtains a self-adhesive surface protective film which excels in processability of the film. The film shows high adhesive force to the covering product and can be used in various covering product. It also can keep the adhesive film in a roll at the same time, and even as the film is subsequently drawn out, the problems for partly stretching, transforming the film are hardly to be caused. The present invention is a polyolefin based film characterized in that the resin constituting the mold release layer at least comprises block copolymer of propylene and ethylene, and α -olefin (co)polymer having carbon number of 4 or more. The use level of α -olefin (co)polymer having carbon number more than 4 is 5 weight% or more and less than 35 weight% of the components of the resin constituting the mold release layer. The polyolefin based film is fabricated to laminate the adhesive layer on one surface of the base material layer constituted of polypropylene resin and laminate the mold release layer on the other surface. The surface roughness (SRa) is 0.20 μ m or more and 0.50 μ m or less.

Description

Polyolefin film

The present invention relates to a polyolefin-based film which can be used for parts such as rugs for optical applications, synthetic resin sheets (for example, for building materials), and stainless steel sheets (for example, building materials). ), aluminum plate, decorative plywood, steel plate, glass plate, home appliances, precision machinery, etc. Further, the polyolefin-based film can be applied to protect the surface of the vehicle body during production, to avoid damage during stacking, storage, transportation, and conveyance of articles in the manufacturing process, and to avoid secondary processing (for example, bending processing or Damage during processing).

In the past, an adhesive film for the purpose of surface protection of a covering body can be used for processing, storage, and transportation of building materials, electrical, electronic products, automobiles, etc., and such an adhesive film has good adhesion and is used after use. It must not be contaminated by the adhesive to each surface and can be easily peeled off.

In recent years, with the diversification of the above-mentioned coverings, not only can the coating surface be smooth, but also many surface irregularities can be seen. The covering body having the surface unevenness may, for example, be a 镜片-type lens portion of a cymbal used for an optical component. In order to exhibit sufficient adhesion for use in a coated body having surface irregularities, for example, it is conceivable to increase the adhesion of the adhesive layer and the like so that an adhesive force can be obtained even if the contact area is small.

In order to improve the adhesion of the adhesive layer, it is possible to use a styrene-based elastomer or an olefin-based elastomer which exhibits high adhesion as a resin. Although it is a main component, when the adhesive force of the adhesive layer is raised, the adhesive film is stored in a roll state, and then when the film is transferred out, adhesion occurs and the film partially elongates and deforms.

As a countermeasure against the above, the α-olefin copolymer having 4 or more carbon atoms can be used for the release layer, and the adhesion at the time of transferring the film can be improved (for example, see Patent Document 1). However, in order to laminate a polypropylene resin with a T-shaped die or the like on one surface of a base material layer made of a polypropylene resin, a film containing 50% by weight or more of carbon is deposited by co-extrusion film formation. When the release layer of the α-olefin copolymer is a number of 4 or more, there is a defect that the film forming property of the release layer is deteriorated.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2011-42757

The object of the present invention is to provide a self-adhesive surface protective film which is excellent in processing suitability of a film, which exhibits strong adhesion to a covering body and can be used in various types of coverings while being rolled. In the state where the adhesive film is stored, it is difficult to cause partial elongation or deformation of the film when the film is transferred out. That is, an object of the present invention is to provide a polyolefin-based film which does not cause surface roughening transfer and which does not inhibit adhesiveness and which has excellent peelability and film formability.

The present inventors have intensively studied and found that it is found that the blending ratio or surface roughness of the resin used in the release layer can be set within a predetermined range. The present invention has been achieved by solving the above problems. That is, the present invention relates to a polyolefin-based film characterized in that the resin constituting the release layer contains at least a block copolymer of propylene and ethylene, and an α-olefin (co)polymer having a carbon number of 4 or more, and has a carbon number of 4 The above-mentioned α-olefin (co)polymer is blended in an amount of 5% by weight or more and less than 35% by weight based on the resin component constituting the release layer, and is coextruded on a substrate layer composed of a polypropylene resin. The one-layer adhesive layer is formed on the other surface layer, and the surface roughness (SRa) of the release layer is 0.20 μm or more and 0.50 μm or less.

In this case, the α-olefin copolymer having 4 or more carbon atoms is preferably a 4-methyl-1-pentene-based (co)polymer.

Moreover, in this case, the MFR (230 ° C, 2.16 Kgf) of the polypropylene resin is preferably 1.0 to 15 g/10 min.

Further, in this case, at least the styrene-based elastomer is used as the adhesive layer, and the MFR (230 ° C, 2.16 Kgf) of the styrene-based elastomer is preferably 0.5 to 20 g/10 min.

The polyolefin-based film of the present invention exhibits a strong adhesive force to the covering, and can be used in various types of coverings, and the adhesive film is stored in a roll state, and then it is difficult to cause the film portion to be partially transferred when the film is transferred out. It has problems such as elongation, deformation, and the like, and has an advantage that the film has excellent processing suitability. That is, according to the present invention, it is possible to provide a polyolefin-based film which does not cause surface rough transfer and which does not inhibit adhesiveness and which has good peelability and film formability.

[Formation of the Invention]

Hereinafter, an embodiment of the polyolefin-based film (adhesive film) of the present invention will be described.

(base material layer)

The polyolefin-based film of the present invention requires a base material layer containing a polypropylene-based resin as a main component, and examples of the polypropylene-based resin used herein include random polypropylene, propylene, and a small amount of α-olefin. In particular, the crystalline polypropylene resin may, for example, be an n-heptane-insoluble homopolymer propylene homopolymer used in general extrusion molding or the like, or may contain 60% by weight or more. The copolymer of propylene propylene and other α-olefins may be used singly or in combination as a copolymer of propylene or other α-olefin. The base material layer preferably contains 50% by weight or more of propylene units, more preferably 60% by weight or more of propylene units. When the amount of propylene is less than 50% by weight, the film becomes tackless and becomes difficult to handle.

Here, the term "n-heptane insoluble" means safety while indicating the crystallinity of the polypropylene, and in the present invention, the use is in accordance with the Ministry of Welfare No. 20 of February 1982. The n-heptane insoluble property (the elution component at the time of extraction at 25 ° C for 60 minutes is 150 ppm or less [30 ppm or less when the temperature exceeds 100 ° C) is preferable.

The α-olefin copolymerization component of the copolymer of propylene and another α-olefin is preferably an α-olefin having a carbon number of 2 to 8, such as ethylene or 1-butene or 1-pentene. An α-olefin of C4 or higher such as hexene or 4-methyl-1-pentene. Here, the copolymer is preferably a random or block copolymer obtained by polymerizing propylene with one or more kinds of the above-exemplified α-olefins. Make The melt flow rate (MFR: 230 ° C, 2.16 Kgf) of the polypropylene resin to be used is preferably in the range of 1.0 to 15 g/10 min, more preferably in the range of 2.0 to 10.0 g/10 min. Further, a copolymer of two or more kinds of propylene and another α-olefin may be used in combination. Further, the waste film produced by processing the film obtained by the present invention as a raw material for recycling can be regranulated and added to the substrate layer, and the production cost can be controlled by using the recycled raw material.

(adhesive layer)

The adhesive layer of the polyolefin-based film of the present invention can be used as long as it is a known adhesive, and is preferably a styrene-based elastomer or an olefin-based elastomer. In particular, in order to exhibit high adhesion, a styrene-based elastomer can be suitably used. Further, in order to control the adhesion, a polyolefin resin, an adhesion-imparting resin, and a softener may be mixed as needed.

Examples of the styrene-based elastic system include styrene-butadiene-styrene, styrene-isoprene-styrene, styrene-ethylene/butene copolymer-styrene, styrene-ethylene/propylene copolymer- AB block of ABA type block polymer such as styrene, styrene-butadiene, styrene-isoprene, styrene-ethylene/butene copolymer, styrene-ethylene/propylene copolymer, etc. A styrene-based random copolymer such as a polymer or a styrene-butadiene rubber, and the like.

The melt flow rate (MFR: 230 ° C, 2.16 Kgf) of the styrene-based elastomer to be used is preferably in the range of 0.5 to 20 g/10 min, more preferably in the range of 2.0 to 15.0 g/10 min, still more preferably 3 A range of ~10 g/10 minutes, particularly preferably in the range of 4 to 7 g/10 minutes.

Styrene-based elastomer in the adhesive layer (resin component constituting the adhesive layer) It is preferably 50% by weight or more, more preferably 60% by weight or more, still more preferably 70% by weight or more, still more preferably 75% by weight or more, more preferably 100% by weight or less, still more preferably 99% by weight or less. Further preferably, it is 98% by weight or less, and more preferably 97% by weight or less.

The styrene component in the styrene elastomer is preferably 5% by weight or more and 30% by weight or less. When it is less than 5% by weight, granulation at the time of resin production becomes difficult, and if it exceeds 30% by weight, the adhesive force is lowered, and it becomes difficult to obtain a desired adhesive force. Further, the styrene component in the styrene elastomer is preferably 10% by weight or more and 25% by weight or less, more preferably 10% by weight or more and 20% by weight or less, still more preferably 10% by weight or more and 15% by weight or less. Further, the component other than the styrene component in the styrene elastomer is preferably composed of a component such as ethylene or butylene, and the component amount other than the styrene component is preferably 70 to 95 in the styrene elastomer. The weight %, more preferably 75 to 90% by weight, more preferably 80 to 90% by weight, still more preferably 85 to 90% by weight.

Examples of the olefin-based elastic system include an α-olefin polymer or copolymer having 2 to 20 carbon atoms, a copolymer of ethylene and an unsaturated carboxylic acid or an unsaturated carboxylic acid ester, and the like. The melt flow rate (MFR: 230 ° C, 2.16 Kgf) of the olefin-based elastomer to be used is preferably in the range of 0.5 to 20 g/10 min, more preferably in the range of 2.0 to 10.0 g/10 min.

The polyolefin-based resin is not particularly limited, and examples thereof include crystalline polypropylene, a copolymer of propylene and a small amount of an α-olefin, a low-density polyethylene, a high-density polyethylene, a copolymer of ethylene and a small amount of an α-olefin, and ethylene. Copolymer of unsaturated carboxylic acid or unsaturated carboxylic acid ester, polystyrene. Among them, the polypropylene resin is composed of a polypropylene resin, and the molten material is formed from a molten state. The relationship between the viscosity and the like can also be suitably used. The melt flow rate (MFR: 230 ° C, 2.16 Kgf) of the polyolefin-based resin to be used is preferably in the range of 1.0 to 100.0 g/10 min, more preferably in the range of 2.0 to 30.0 g/10 min, and more preferably 2 to 2 A range of 10 g/10 minutes, particularly preferably in the range of 2 to 7 g/10 minutes.

When the blending amount of the polyolefin resin in the adhesive layer is preferably 25% by weight or less, and if the blending amount of the polyolefin resin exceeds 25% by weight, the adhesive force is lowered depending on the resin to be used, and sufficient adhesion cannot be obtained. force. The blending amount of the polyolefin resin is preferably 5% by weight or more. When the amount is less than 5% by weight, the adhesion to the release layer is excessively increased, and the selection range of the release layer is small. The blending amount of the polyolefin resin is more preferably 6% by weight or more and 20% by weight or less, still more preferably 6% by weight or more and 15% by weight or less.

Examples of the adhesive-imparting resin include an aliphatic hydrocarbon resin, an aromatic hydrocarbon resin, an alicyclic hydrocarbon resin, an anthracene resin, a benzofuran-indene resin, a styrene resin, a rosin resin, and the like, and among them, an alicyclic group is preferred. Hydrocarbon resin (for example: petroleum resin). The molecular weight of the adhesive-imparting resin is not particularly limited and may be appropriately set. However, if the molecular weight is small, mass transport or heavy peeling of the adherend from the adhesive layer may be caused. On the other hand, the molecular weight When the size is increased, the adhesion promoting effect tends to be poor, so that the number average molecular weight of the adhesion-imparting resin is preferably about 1,000 to 100,000. The blending amount of the adhesion-imparting resin in the adhesive layer is preferably in the range of 5% by weight to 30% by weight, and if the blending amount of the tackifying resin is more than 30% by weight, the molecular weight of the adhesive-imparting resin is low, resulting in a molten state. The viscosity is extremely low, and when a co-extrusion film formation using a T-shaped die or the like is performed, a base mainly composed of a polypropylene-based resin is used. The accumulation between the layers becomes difficult. In addition, when the amount of the adhesion-imparting resin in the adhesive layer is less than 5% by weight, there is a concern that the adhesion of the adhesive layer does not contribute to the change. The blending amount of the tackifying resin is more preferably 6% by weight or more and 25% by weight or less, still more preferably 6% by weight or more and 20% by weight or less, still more preferably 6% by weight or more and 15% by weight or less, particularly preferably 6% by weight or less. Above 10% by weight or less.

Examples of the softening agent include a low molecular weight diene polymer, polyisobutylene, hydrogenated polyisoprene, hydrogenated polybutadiene or the like, polybutene, and the like. The molecular weight of the softener is not particularly limited and may be appropriately set. However, if the molecular weight is small, mass transfer or heavy peeling of the adherend from the adhesive layer may occur, and if the molecular weight is increased, Since the adhesion improving effect tends to be poor, the number average molecular weight of the softener is preferably about 1,000 to 100,000.

Further, the adhesive-imparting resin or softener used in the adhesive layer is a liquid or a powder depending on the type, and there is also a person who contaminates the extruder at the time of extrusion. Such a problem can be improved by using a binder resin or a softener and a polyolefin resin as a masterbatch. Therefore, it is preferred to use a binder resin or a softener and a polyolefin resin.

The adhesiveness of the polyolefin-based film of the present invention is in the range of 200 to 900 cN/25 mm for the acrylic plate at 23 ° C, but it is preferably used in various types of coatings. When the adhesive force is less than 200 cN/25 mm, curling or the like may occur due to the covering during the protection, and the function as a protective film cannot be carried. On the other hand, when the adhesive force exceeds 900 cN/25 mm, there is a possibility that the film cannot be peeled off smoothly when the film is peeled off from the crepe sheet. The adhesive force can be appropriately set by changing the resin composition or thickness of the adhesive layer. Adhesion More preferably, it is 300 cN/25 mm or more and 900 cN/25 mm or less, and more preferably 400 cN/25 mm or more and 800 cN/25 mm or less.

The polyolefin-based film of the present invention may optionally contain a known additive, and may, for example, contain a lubricant, an anti-caking agent, a heat stabilizer, an antioxidant, an antistatic agent, a light stabilizer, and an impact modifier. And preferably, wherein the low molecular weight substance on the surface of the adhesive layer is less than 1 mg/m ² .

Here, the measurement of the low molecular weight substance on the surface of the adhesive layer is carried out in the following order. After washing the surface of the adhesive layer with an organic solvent such as ethanol which does not attack the resin constituting the adhesive layer, the organic solvent is removed from the cleaning solution by an evaporator or the like, and the value obtained by weighing the residue is divided by washing. The surface area of the surface of the adhesive layer is obtained. Here, if there is a residue of 1 mg/m ² or more, foreign matter is present between the surface of the adhesive layer and the surface of the adherend, which results in a reduction in the contact area and a reduction in the vanaural force, so that the adhesive strength is not lowered. When an additive is added, it is necessary to select an additive such as a polymer type, or to investigate the amount of addition and the method of addition, and the like, and there is no migration or transfer of the adhesive layer.

(release layer)

The polyolefin-based film of the present invention forms a release layer on the other surface of the adhesive layer of the one-layer layer of the base material layer, and even if the films are overlapped with each other, the adhesion of the films to each other is small, and in particular, the film is stored in a roll state. Then, when the film is transferred out, it is difficult to cause a problem that the film is partially elongated, deformed, and the like, and the film has excellent processing suitability. In order to make the films adhere to each other even if the films are overlapped with each other, it is effective to form surface irregularities in the release layer and to reduce the contact area with the adhesive layer.

In order to form the surface unevenness as described above, propylene may be suitably used. Ethylene block copolymer. The surface roughness can be increased by increasing the molecular weight of the ethylene-propylene rubber in the propylene-ethylene block copolymer or increasing the amount of ethylene. Also, surface roughness can be increased by mixing an incompatible resin to the propylene-ethylene block copolymer. Further, in the pressing step, the surface roughness can be further increased by lowering the shear rate with respect to the resin or increasing the residence time. On the other hand, a homopolymer polypropylene resin may be mixed in the propylene-ethylene block copolymer to reduce surface roughness.

In the case of a resin which is insoluble in the propylene-ethylene block copolymer, a (co)polymerization of an α-olefin having a carbon number of 4 or more, such as a 4-methyl-1-pentene-based (co)polymer, can be suitably used. Other examples include low density polyethylene, high density polyethylene, copolymer of ethylene and a small amount of α-olefin, copolymer of ethylene and vinyl acetate, polystyrene, polyester resin, and polyamide resin. Wait. In particular, the 4-methyl-1-pentene (co)polymer not only roughens the surface in the form of a mat, but it is also expected to further improve the peeling property by lowering the surface free energy of the surface of the film.

Further, the unevenness of the surface may be achieved by adding the above-mentioned incompatible resin to the homo-propylene or the random polypropylene. However, when the propylene-ethylene block copolymer is used, the production machine may be changed or manufactured according to the production machine. The melt-mixed chain condition at the time of filming is difficult to change in the uneven state, and stable production is possible.

The blending amount of the α-olefin (co)polymer having 4 or more carbon atoms in the release layer (resin component constituting the release layer) is in the range of 5% by weight to 35% by weight. When the blending amount of the α-olefin (co)polymer having 4 or more carbon atoms exceeds 35% by weight, it is desired to form a film by co-extrusion at a general temperature at which a polypropylene resin is extruded using a T-shaped die or the like. When a release layer is laminated on one surface of a base material layer made of a polypropylene resin, the film formation property of the release layer is deteriorated. . When the blending amount of the α-olefin (co)polymer having 4 or more carbon atoms is less than 5% by weight, the release force of the release layer does not contribute to improvement. The blending amount of the α-olefin (co)polymer having 4 or more carbon atoms is preferably 7% by weight or more and 33% by weight or less. Further, when the molecular weight of the α-olefin (co)polymer having 4 or more carbon atoms is small, migration from the release layer to the mass of the adhesive layer may occur, and therefore the number average molecular weight of the adhesion-imparting resin is preferably 10,000. ~1 million or so.

Weight ratio of propylene-ethylene block copolymer to 4-methyl-1-pentene (co)polymer in the release layer (propylene-ethylene block copolymer/4-methyl-1-pentene) The (co)polymer) is preferably 95/5 to 65/35, more preferably 93/7 to 67/33.

In view of the resin composition of the adhesive layer in the present invention, it is preferred that the average surface roughness SRa of the surface of the release layer be 0.20 μm or more and 0.50 μm or less. By doing so, the adhesion resistance and the protective properties of the adherend can be improved. When the surface roughness of the release layer is lowered to be lower than 0.20 μm, the film transfer property when the film is formed into a roll form is deteriorated. When the surface roughness of the release layer is raised to be higher than 0.50 μm, the surface unevenness of the release layer is transferred to the surface of the adhesive layer, and the adhesion is remarkably lowered.

In this case, the surface unevenness of the release layer is more preferably a surface having a surface roughness of SRa of 0.25 μm or more and 0.45 μm or less.

The haze of the release layer having such a surface roughness is preferably 20% or more and 80% or less, and the haze of the film is better in order to make it easier to distinguish as a protective film adhered to the covering. It is 30% or more, and the haze is more preferably 70% or less in order to easily detect foreign matter using a foreign matter detector during film formation.

The peeling force of the release surface of the adhesive surface of the polyolefin-based film of the present invention is preferably 200 cN/25 mm or less at 23 ° C from the viewpoint of the film-transfer property when the adhesive film is formed into a roll form. . When the peeling force exceeds 200 cN/25 mm, the film is ejected when the adhesive film is formed into a roll form, which causes a problem that the film is partially elongated and deformed. The peeling force can be appropriately set by changing the addition amount or surface roughness of the α-olefin copolymer having 4 or more carbon atoms in the release layer.

In addition, the lower limit of the peeling force of the release surface of the adhesive surface of the polyolefin-based film is about 1 cN/25 mm, and further about 5 cN/25 mm.

The thickness of the adhesive layer of the polyolefin-based film 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, it is difficult to form a film by co-extrusion, and if it is 30 μm or more, it is a film which is disadvantageous in terms of cost.

At this time, when the adhesive force is increased, it is preferable to increase the thickness in consideration of the viscosity. By increasing the thickness of the adhesive layer, it is easy to increase the contact area with the adherend. 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 base material layer of the polyolefin-based film of the present invention is preferably 5 μm or more and less than 100 μm, more preferably 10 μm or more and less than 75 μm, still more preferably 15 μm or more and less than 40 μm. When the thickness of the base material layer is less than 5 μm, the toughness is deteriorated, and wrinkles are likely to occur when the protective film is adhered to the covering, and the adhesive strength cannot be sufficiently obtained. When the thickness is 100 μm or more, the cost is increased. Unfavorable film.

The thickness of the release layer of the polyolefin-based film 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, it is difficult to form a film by co-extrusion, and if it is 30 μm or more, it is a film which is disadvantageous in terms of cost.

In this case, the thickness of the release 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 polyolefin-based film of the present invention is composed of each of a base layer, an adhesive layer, and a release layer containing the above-described resin component, and each layer may have one or two or more layers as long as the effects of the present invention are exhibited. The resin constituting each layer may be, for example, a uniaxial or biaxial extruder or the like, and maintained in a molten state and sent out to a feed block type T-shaped die and laminated to form at least 3 A layer of a polyolefin-based film. The temperature of the extruder of each layer can be appropriately adjusted in consideration of the molding temperature of the components used for each layer in order to make each layer in a molten state, and can be adjusted, for example, in the range of 200 ° C to 260 ° C. The temperature of the T-shaped die can be the same as the above temperature. The winding speed from the T-shaped 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 50 m/min, preferably 10 m/min to 30 m/min.

The polyolefin-based film of the present invention is preferably in the form of a roll, and the upper limit of the width of the film roll and the winding length is not particularly limited. However, in view of easiness of handling, the width is generally 1.5 m or less. The winding length is preferably 6000 m or less at a film thickness of 30 μm. Further, as the core of the winding, a plastic core such as 3 吋, 6 吋, or 8 或 or a metal core can be generally used. Moreover, from the viewpoint of the suitability for processing, a film roll wound up to a size of 200 m or more and a width of 450 mm or more is preferable.

The polyolefin-based film of the present invention can be used for optical applications. Parts such as crepe sheets, synthetic resin sheets (for example, for building materials), stainless steel sheets (for example, for building materials), aluminum sheets, decorative plywood, steel sheets, glass sheets, home electric appliances, precision machinery, and the like. Moreover, the polyolefin-based film of the present invention can be suitably used for the purpose of protecting the surface of the vehicle body during production, in order to avoid damage during stacking, storage, transportation, and transportation of articles in the manufacturing process, and to avoid secondary processing (for example, bending) Damage when processing or pressing) the article.

The present application claims the priority of Japanese Patent Application No. 2011-238934, filed on Oct. 31, 2011, the entire disclosure of The content is cited as a reference in this case.

[Examples]

The present invention will be further illustrated by the following examples, but the invention is not limited by the examples described below. The physical property evaluation methods in the following examples and comparative examples are as follows.

(1) Evaluation of adhesion

The measurement was carried out in the following manner in accordance with JIS-Z-0237 (2000) Adhesive tape and adhesive sheet test method.

A 50 mm × 150 mm acrylic plate (manufactured by Mitsubishi Rayon Co., Ltd.: ACRYLITE (registered trademark) 3 mm thick) was prepared as a bonded body, and a test piece of 150 mm was cut in the winding direction at the time of film production, and a test piece of 25 mm was cut in a direction perpendicular thereto. For the sheet, a rubber roller of 2000 g in mass (the spring hardness of the roller surface is 80 Hs, the rubber layer having a thickness of 6 mm is covered with a width of 45 mm, and the diameter (including the rubber layer) is 95 mm), at a speed of 5 mm/sec. The adhesive body and the test piece were subjected to 1 back and forth pressure bonding. After being pressure-bonded, the product was placed at a temperature of 23 ° C and a relative humidity of 65% for 30 minutes at an altitude of 300 mm/min using "Autograph (registered trademark)" (AGS-J) manufactured by Shimadzu Corporation. The resistance value at the time of peeling was used as the adhesive force [cN/25 mm]. The 180-degree peeling means that the peeling angle of the acrylic sheet and the film when the resistance value at the time of peeling is measured is maintained 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 was prepared as an exposed core of the electrode for measuring the sample, and the end of the pressure-sensitive adhesive film and the acrylic film on the side of the adhesive film was 15 mm at the adhesive portion. Apply the Scotch Tape under the width to make the bare end of the electrode during the measurement. A schematic diagram of the measurement sample is shown in Fig. 1. The measurement system was performed three times on one sample, and the average value was used as the adhesion of the sample.

(2) Evaluation of adhesion resistance

For the acrylic sheet (Mitsubishi RAYON Co., Ltd.: ACRYLITE (registered trademark) 3mm thick) 50mm × 150mm double-sided tape (Nitto Electric Co., Ltd.: No. 535A), in order to become the adhesive surface of the test piece 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 adhered to the other surface of the double-sided tape.

A test piece of 25 mm was cut in the winding direction at the time of film production, and a test piece of 25 mm was cut in a direction perpendicular thereto as a new test piece, and the adhesive surface was overlapped with the release surface of the test piece to which the acrylic plate was adhered through the double-sided tape. , using a rubber roller of 2000g mass (the spring hardness of the roller surface is 80Hs, the rubber layer with a thickness of 6mm is covered with a width of 45mm, and the diameter (including the rubber layer) is 95mm), and the release surface and the test are performed at a speed of 5mm/sec. The sheet was subjected to 1 back and forth pressure bonding. After being pressure-bonded, the product was placed at a temperature of 23 ° C and a relative humidity of 65% for 30 minutes at an altitude of 300 mm/min using "Autograph (registered trademark)" (AGS-J) manufactured by Shimadzu Corporation. The resistance value at the time of peeling was taken as the peeling force [cN/25 mm].

At the time of measurement, a polyester sheet having a thickness of 190 μm and a size of 25 mm × 170 mm was prepared as the bare end of the electrode for measuring the sample, and was adhered to the end of the test piece of 150 mm × 25 mm at a width of 15 mm at the adhesion point, and the electrode was measured at the time of measurement. Bare end. The measurement system was performed three times on one sample, and the average value was taken as the peeling force of the sample.

(3) Determination of average surface roughness

Using a contact type three-dimensional center surface roughness meter (type ET-30HK) manufactured by Otaru Research Institute, the probe method was used to measure the center-surface average roughness (SRa) of the surface of the release layer under the following conditions. . The conditions are as follows, and the average value of the three measurements is taken as a numerical value.

Probe tip radius: 0.5μm

Probe pressure: 20mgf

Cutoff: 80μm

Measurement length: 1000μm

Measurement speed: 100 μm / sec

Measurement interval: 2μm

(4) Determination of haze

According to the optical property test method of JIS-K-7105 Plastic, it was measured using Haze Meter (NDH-2000) manufactured by Nippon Denshoku Industries Co., Ltd.

(5) Transferring the surface of the release layer of the adhesive layer

Using a digital microscope (VHX-200F) made by KEYENCE, with magnification 100 times the digital image of the adhesive surface of the film. The transfer from the release layer is less likely to occur as ○, and the transfer is very severe as ×.

(6) Film forming properties

When a film is produced, it is possible to form a film with a uniform thickness of ○, and it is not possible to form a film with a uniform thickness.

[Example 1] (Production of substrate layer)

Use 120mm at 240 ° C A uniaxial extruder melt-extruded 100 wt% of the homopolypropylene resin (manufactured by Sumitomo Chemical Co., Ltd.: FLX80E4, MFR: 7.5 g/10 min) to form a substrate layer.

(production of adhesive layer)

Use 90mm at 220 °C A uniaxial extruder consists of 85 wt% of a styrene-based elastomer (manufactured by ASAHI KASEI CHEMICALS: Tuftec (registered trademark) H1221, styrene copolymerization ratio of 12 wt%, MFR: 4.5 g/10 min), and 7.5 wt% of homopolymers. Acrylic resin (manufactured by Sumitomo Chemical Co., Ltd.: FS2011DG3, MFR: 2.5 g/10 min), and 7.5 wt% of petroleum resin (ARKON (registered trademark) P125 manufactured by Arakawa Chemical Industry Co., Ltd.) were melt-extruded to form an adhesive layer.

(production of release layer)

Use 90mm at 250 °C A uniaxial extruder melt-extruded 92 wt% of a propylene-ethylene block copolymer (manufactured by Nippon Polypropylene: BC4FC) and 8 wt% of polymethylpentene (manufactured by Mitsui Chemicals: RT31) to form a release layer.

(production of film)

The base material layer, the adhesive layer, and the release layer were each maintained in a molten state at a temperature of 245 ° C in a three-layer T-shaped die (feed set type, lip width (850 mm) width, lip) Multi-layer extrusion in the valve gap 1mm) . The extruded film was taken up at a speed of 20 m/min against a casting roll at a temperature of 30 ° C, and solidified by cooling to obtain three kinds of three layers having a substrate layer thickness of 28 μm, an adhesive layer thickness of 6 μm, and a release layer thickness of 6 μm. Unstretched film.

[Embodiment 2]

Adhesive layer and base material layer According to Example 1, the release layer was changed to the following, and three kinds of three-layer unstretched films were obtained by the same method as in Example 1.

(production of release layer)

Use 90mm at 250 °C A uniaxial extruder melt-extruded 76 wt% of a propylene-ethylene block copolymer (made by Japan Polypropylene: BC3HF) and 24 wt% of polymethylpentene (manufactured by Mitsui Chemicals: RT31) to form a release layer.

[Example 3]

In the substrate layer, the adhesive layer and the release layer were changed to the following contents in the same manner as in Example 1, and three kinds of three-layer unstretched films were obtained by the same method as in Example 1.

(production of adhesive layer)

Use 90mm at 220 °C The uniaxial extruder will mix a styrene-based elastomer at a ratio of 80/7.5/12.5 wt% (manufactured by ASAHI KASEI CHEMICALS: Tuftee (registered trademark) H1221, styrene copolymerization ratio: 12 wt%, MFR: 4.5 g/10 min) A petroleum resin (made by Arakawa Chemical Co., Ltd.: ARKON (registered trademark) P125) and a homopolypropylene resin (manufactured by Sumitomo Chemical Co., Ltd.: FS2011DG3, MFR: 2.5 g/10 min) were melt-extruded to form an adhesive layer.

(production of release layer)

Use 90mm at 250 °C A uniaxial extruder melt-extruded 92 wt% of a propylene-ethylene block copolymer (made of Japanese polypropylene: BC3HF) and 8 wt% of polymethylpentene (manufactured by Mitsui Chemicals: RT31) to form a release layer.

[Example 4]

In the substrate layer, the adhesive layer and the release layer were changed to the following contents in the same manner as in Example 1, and three kinds of three-layer unstretched films were obtained by the same method as in Example 1.

(production of adhesive layer)

Use 90mm at 240 ° C The uniaxial extruder will mix a styrene-based elastomer in a ratio of 90/10 wt% (manufactured by ASAHI KASEI CHEMICALS: Tuftec (registered trademark) H1221, styrene copolymerization ratio: 12 wt%, MFR: 4.5 g/10 min) and the same element. Polypropylene resin (manufactured by Sumitomo Chemical Co., Ltd.: FS2011DG3, MFR: 2.5 g/10 min) was melt-extruded to form an adhesive layer.

(production of release layer)

Use 90mm at 250 °C A uniaxial extruder melt-extruded 92 wt% of a propylene-ethylene block copolymer (made by Japan Polypropylene: BC3HF) and 8 wt% of polymethylpentene (manufactured by Mitsui Chemicals: RT31) to form a release layer.

[Reference Example 1]

In the substrate layer, the adhesive layer and the release layer were changed to the following contents in the same manner as in Example 1, and three kinds of three-layer unstretched films were obtained by the same method as in Example 1.

(production of adhesive layer)

Use 90mm at 240 ° C A uniaxial extruder melt-extruded 100 wt% of a styrene-based elastomer (manufactured by ASAHI KASEI CHEMICALS: Tuftec (registered trademark) H1221, styrene copolymerization ratio: 12 wt%, MFR: 4.5 g/10 min) to form an adhesive layer. .

(production of release layer)

Use 90mm at 250 °C A uniaxial extruder was used to melt-extrude a 68 wt% propylene-ethylene block copolymer (manufactured by Nippon Polypropylene: BC4FC) and 32 wt% of polymethylpentene (manufactured by Mitsui Chemicals: RT31) to form a release layer.

[Comparative Example 1]

The base material layer and the adhesive layer were changed to the following contents in the same manner as in Example 1, and three types of three-layer unstretched films were obtained by the same method as in Example 1.

(production of release layer)

Use 90mm at 250 °C A uniaxial extruder melt-extruded 100 wt% of a propylene-ethylene block copolymer (manufactured by Nippon Polypropylene: BC4FC) to form a release layer.

[Comparative Example 2]

The base material layer and the adhesive layer were changed to the following contents in the same manner as in Example 1, and three types of three-layer unstretched films were obtained by the same method as in Example 1.

(production of release layer)

Use 90mm at 250 °C A uniaxial extruder melt-extruded 96 wt% of a propylene-ethylene block copolymer (made by Japan Polypropylene: BC4FC) and 4 wt% of polymethylpentene (manufactured by Mitsui Chemicals: RT31) to form a release layer.

[Comparative Example 3]

The base layer and the adhesive layer were changed to the following contents in the same manner as in Example 1. Although three kinds of three-layer unstretched films were obtained by the same method as in Example 1, the thickness precision was poor and the energy was not obtained. A film that is evaluated.

(production of release layer)

Use 90mm at 250 °C A uniaxial extruder melt-extruded 50 wt% of a propylene-ethylene block copolymer (made of Japanese polypropylene: BC3HF) and 50 wt% of polymethylpentene (manufactured by Mitsui Chemicals: RT31) to form a release layer.

[Comparative Example 4]

The base material layer and the adhesive layer were changed to the following contents in the same manner as in Example 1, and three types of three-layer unstretched films were obtained by the same method as in Example 1.

(production of release layer)

Use 90mm at 250 °C The uniaxial extruder has 75 wt% of a propylene-ethylene block copolymer (made of Japanese polypropylene: BC3HF), 6 wt% of polymethylpentene (manufactured by Mitsui Chemicals, Inc.: RT31), and 19 wt% of the same polypropylene resin. (Sumitomo Chemical: FLX80E4, MFR: 7.5 g/10 min) was melt extruded to form a release layer.

[Comparative Example 5]

The base material layer and the adhesive layer were changed to the following contents in the same manner as in Example 1, and three types of three-layer unstretched films were obtained by the same method as in Example 1.

(production of release layer)

Use 90mm at 250 °C The uniaxial extruder has 64 wt% of propylene-ethylene block copolymer (made of Japanese polypropylene: BC4FC), 16 wt% of polymethylpentene (manufactured by Mitsui Chemicals: RT31), and 20 wt% of low density polyethylene resin. (Ube Industries: R300) is melt extruded to form a release layer.

The above results are shown in Tables 1 and 2.

As is apparent from Table 1, the films obtained in Examples 1 to 4 have a practically sufficient adhesive force when used as a protective film, and have no surface roughness transfer, and the film is peeled off as a roll. Good, good film forming properties.

On the other hand, in the films obtained in Comparative Examples 1 and 2 and 4, the peeling property when the film was transferred as a roll was not considered to be good. The film obtained in Comparative Example 5 was severely roughened from the surface of the release layer to the adhesive layer. In the production method of Comparative Example 3, the film forming property was poor and a film capable of withstanding evaluation could not be obtained. As described above, the films obtained in the comparative examples were all of poor quality and low in practicality.

[Industrial availability]

The polyolefin-based film of the present invention can be used for synthetic resin sheets (for example, for building materials), stainless steel sheets (for example, for building materials), aluminum sheets, decorative plywood, steel sheets, glass sheets, home electric appliances, precision machines, and the like. Moreover, the polyolefin-based film of the present invention can be suitably used for the purpose of protecting the surface of the vehicle body during production, in order to avoid damage during stacking, storage, transportation, and transportation of articles in the manufacturing process, and to avoid secondary processing (for example, bending) Damage to the industry when processing or pressing) has a great contribution to the industry.

1‧‧‧ upper chuck

2‧‧‧ polyester sheet

3‧‧‧Acrylic board

4‧‧‧Sco tape

5‧‧‧Adhesive film

6‧‧‧Lower chuck

7‧‧‧Stretching direction

Figure 1 is a schematic diagram of the measurement sample.

Claims (4)

A polyolefin-based film characterized in that the resin constituting the release layer contains at least a block copolymer of propylene and ethylene, an α-olefin (co)polymer having 4 or more carbon atoms, and an α-olefin having 4 or more carbon atoms (total The blending amount of the polymer is 5% by weight or more and less than 35% by weight in the resin component constituting the release layer, and is coextruded in a one-layer adhesive layer of a base material layer composed of a polypropylene-based resin. The other layer is formed of a release layer, and the surface roughness (SRa) of the release layer is 0.20 μm or more and 0.50 μm or less. The polyolefin-based film according to claim 1, wherein the α-olefin (co)polymer having 4 or more carbon atoms is a 4-methyl-1-pentene (co)polymer. The polyolefin-based film of claim 1 or 2, wherein the polypropylene resin has an MFR (230 ° C, 2.16 Kgf) of 1.0 to 15 g/10 min. The polyolefin-based film according to any one of claims 1 to 3, wherein at least the styrene-based elastomer is used for the adhesive layer, and the MFR (230 ° C, 2.16 Kgf) of the styrene-based elastomer is 0.5 to 20 g. /10 minutes.