JP6515917B2 - Self-adhesive surface protection film - Google Patents

Description

  The present invention relates to an adhesive film. The pressure-sensitive adhesive film of the present invention is used to protect articles from being stacked, stored, transported, or damaged during transportation in the manufacturing process, in order to protect members such as prism sheets used in optical applications. Can be suitably used.

  Heretofore, adhesive films intended for surface protection of coverings have been used during processing, storage and transportation of construction materials, electricity, electronic products, automobiles, etc. Such adhesive films have good adhesiveness. As well as having them, after use, they should be able to be easily peeled off without contaminating each surface with an adhesive.

In recent years, the coating described above has been diversified, and not only a coating having a smooth surface but also a coating having a surface asperity may be seen. As a covering which has surface asperity, a prism type lens part of a prism sheet used for an optical member, etc. are mentioned, for example. In order to develop sufficient adhesion for use with a cover having a surface asperity such as a prism sheet, the adhesion of the adhesion layer is increased so that adhesion can be obtained even if the contact area is small, etc. Is considered.

  In order to increase the adhesive strength of the adhesive layer, it is possible to use a styrenic elastomer or the like exhibiting high adhesive strength as a resin as a main component, but when the adhesive strength of the adhesive layer is increased, the film is stored in a roll When the film is subsequently fed out, blocking occurs between the adhesive layer and the film surface on the opposite side of the adhesive layer, causing problems such as partial stretching and deformation of the film. Furthermore, when the blocking is severe, the feeding sound becomes large when the film is fed out, and there is also a problem that the surrounding work environment is significantly deteriorated as a noise.

  When forming an adhesive film by melt-extruding all layers of the film, as the above-mentioned measures, fluorocarbon resin, silicon resin (for example, refer to patent documents 1, 2 etc.) and saturated fatty acid bisamide in the base material layer. (For example, refer to Patent Document 3 and the like.) Studies have been made to add it, etc. However, there is a possibility that these resins may transfer to the adhesive layer when storing them in roll state, which lowers the adhesive force. Or contaminating the coating, etc. can not be wiped out.

  In addition, using a styrene-based elastomer for the adhesive layer has also been studied (see, for example, Patent Documents 4, 5, 6, etc.), but the adhesive force to the prism and the film are stored in a roll state, Both of the above problems in feeding the film were not satisfied.

On the other hand, it has been proposed to manufacture an optical member by punching out a long sheet obtained by sticking an adhesive film to the above-mentioned prism sheet with a mold (see Patent Document 7 etc.). When peeling off the adhesive film from the optical member punched out with a mold, the end of the adhesive film is grasped and peeled off. However, when the die is used for punching, the adhesive film and the prism sheet may be difficult to peel off. .
The above-mentioned phenomenon occurs when the adhesive layer of the adhesive film bites into the asperities of the prism sheet by punching, and the end becomes extremely difficult to peel off.

  Although the adhesion layer which uses a styrene system elastomer as a main raw material, and contains an imine system compound and fatty acid amide as a measure of the above is proposed (refer to patent documents 8 grade), when storing all in roll state, an adhesion layer These resins can migrate and do not wipe away concerns such as reduced adhesion or contamination of the coating.

JP 2008-81589 A JP 2008-308559 A Patent No. 4565058 gazette Japanese Patent Application Publication No. 08-73822 JP 2007-161882 A JP 2007-332329 A Japanese Patent Application Publication No. 2007-187781 JP, 2012-117013, A

  The problem to be solved by the present invention is that when peeling off the adhesive film from the die-cut optical member, the end of the adhesive film can be easily grasped and peeled off, and the adhesive film is stored in a roll state After that, even when the film is subsequently fed out, problems such as partial elongation or deformation of the film hardly occur, and it is an object of the present invention to provide a self-adhesive surface protective film excellent in processability of the film.

As a result of intensive studies, the present inventors have found that the above-mentioned problems can be solved, and reach the present invention.
That is, in the present invention, an adhesive layer is laminated on one side of a base material layer made of a polypropylene resin by coextrusion on the other side, and an adhesive film and an adherend are bonded together, and an end cut with a chisel The self-adhesive surface protective film characterized in that the peel strength of the part is 60 cN / 25 mm or less and the peel force of the adhesive surface to the release surface is 200 cN / 40 mm or less.

  According to the present invention, when peeling off the adhesive film from the optical member punched out with a mold, it is easy to grasp and peel off the end of the adhesive film, store the adhesive film in a roll, and then store the film Even when the film is fed out, problems such as partial elongation and deformation of the film hardly occur, and a self-adhesive surface protective film excellent in processability of the film can be obtained.

  In this case, the melt flow rate (MFR: 230 ° C., 2.16 Kgf) of either the styrenic elastomer A or styrenic elastomer B in the adhesive layer in the preceding period is 0.5 to 8 g / 10 min. It is suitable.

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

  Furthermore, in this case, it is preferable that the resin used for the release layer is a non-silicon resin.

  The pressure-sensitive adhesive film according to the present invention is easy to hold and peel off the end of the pressure-sensitive adhesive film when the pressure-sensitive adhesive film is peeled off from the die-cut optical member. Even when the film is unwound, problems such as partial elongation and deformation of the film hardly occur, and it has an advantage of being excellent in processability of the film.

It is a schematic diagram of a measurement sample. It is a schematic diagram of a measurement. It is a schematic diagram of a measurement.

In the present invention, an adhesive layer is laminated on one side of a base material layer made of a polypropylene resin by coextrusion on the opposite side, and an adhesive film and an adherend are bonded together, and an edge part punched out with a chisel The self-adhesive surface protective film is characterized in that the peel strength of the adhesive is 60 cN / 25 mm or less and the peel force of the adhesive surface to the release surface is 200 cN / 40 mm or less.
Hereinafter, the embodiment of the adhesive film of the present invention will be described.

(Adhesive layer)
As a resin constituting the adhesive layer of the present invention, when peeling the adhesive film from the optical member punched out with a mold, it is easy to grasp and peel off the end of the adhesive film, and the adhesive film is stored in a roll Then, in order to make it difficult to cause problems such as partial stretching or deformation of the film when the film is subsequently fed out, styrenic elastomers are preferably used. In particular, it is preferable to use at least two types of styrenic elastomers having different compositions in order to satisfy the film characteristics. In addition, an olefin resin such as a polyethylene resin, a tackifier resin, a softener, polystyrene, and the like can be mixed as needed to control the adhesive strength.

One of at least two types of styrenic elastomers used is an ABA type block polymer such as styrene-butadiene-styrene, and a hydrogenated product of an AB type block polymer such as styrene-butadiene copolymer. And a hydrogenated product of a block copolymer of a styrene-based polymer block and a butadiene polymer block, and a hydrogenated product of a random copolymer of styrene and butadiene such as a styrene-butadiene rubber can be mentioned.
The melt flow rate (MFR: 230 ° C., 2.16 Kgf) of either the styrenic elastomer A or styrenic elastomer B used is preferably in the range of 0.5 to 8 g / 10 min in terms of film forming property, The range of 2.0 to 7.0 g / 10 min is more preferable.

  The total weight of the styrenic elastomer in the adhesive layer is 60% by weight based on the total weight of the resin composition constituting the adhesive layer in order to develop the peelability from the optical member after punching and the delivery of the film from the roll state. The content is preferably 99% by weight or less. If the weight ratio to the entire resin composition constituting the adhesive layer is less than 60% by weight, the adhesive strength is reduced, and it becomes difficult to obtain the required adhesive strength. The total amount of styrenic elastomer in the adhesive layer is preferably in the range of 65% by weight to 95% by weight.

Also, hydrogen of styrene polymer block and butadiene polymer block copolymer in a mixture of hydrogenated product of styrene copolymer block and butadiene polymer block and random copolymer of styrene and butadiene The weight ratio of the additive is preferably 5% by weight or more. If the weight ratio of the hydrogenated product of the block copolymer of the styrene-based polymer block and the butadiene polymer block is less than 5% by weight, the adhesion is lowered, and it becomes difficult to obtain the required adhesion.
The weight ratio of the styrene polymer block to the hydrogenated product of the butadiene polymer block copolymer is more preferably 8% by weight or more, and particularly preferably 20% by weight or more.
On the other hand, the weight ratio of the hydrogenated substance of the block copolymer of the styrene-based polymer block and the butadiene polymer block is preferably 80% by weight or less. When the weight ratio of the styrene-based polymer block to the hydrogenated product of the butadiene polymer block copolymer exceeds 80% by weight, the feeding properties of the film from the roll state may not be sufficiently expressed.
60 weight% or less is still more preferable, and, as for the weight ratio of the hydrogenated substance of a styrene-type polymer block and a butadiene polymer block copolymer, 40 weight% or less is especially preferable.

Among styrene-based elastomers used, it is desirable that the weight ratio of the styrene component in the hydrogenated substance of the block copolymer of styrene-based polymer block and butadiene polymer block is 5% by weight or more and 40% by weight or less .
When the weight ratio of the styrene component is less than 5% by weight, granulation at the time of resin preparation becomes difficult, and when it exceeds 40% by weight, the adhesion is obtained by blending a styrene / butadiene random copolymer with a hydrogenated substance. It becomes difficult to obtain the necessary adhesive strength.
The weight ratio of the styrene component is preferably in the range of 10% by weight to 30% by weight.
On the other hand, it is desirable that the weight ratio of the styrene component in the styrenic elastomer of the hydrogenated substance of the random copolymer of styrene and butadiene is 40% by weight or more and 70% by weight or less.
When the weight ratio of the styrene component is less than 40% by weight, the unwinding property of the film from the roll state may not be sufficiently expressed, and when it exceeds 70% by weight, the adhesive strength is reduced to obtain the required adhesive strength. It becomes difficult.
The weight ratio of the styrene component is preferably in the range of 45% by weight to 65% by weight.

  Examples of the tackifier 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 possibility that substance transfer from the adhesive layer to the adherend or heavy peeling may occur, while the molecular weight is large. Then, the number average molecular weight of the tackifier resin is preferably about 1,000 to 100,000 because the adhesive improvement effect tends to be poor. The number average molecular weight can be measured by gel permeation chromatography or the like.

The content of tackifying resin in the resin composition constituting the adhesive layer is preferably a mixture of a hydrogenated substance of a block copolymer of a styrene polymer block and a butadiene polymer block and a random copolymer of styrene and butadiene. To 5% by weight or more and less than 25% by weight.
When the content of the tackifying resin exceeds 25% by weight, the viscosity of the tackifying resin is extremely low because the molecular weight is low, and the polypropylene resin is mainly used when performing coextrusion film formation using a T die or the like. Not only the lamination with the base material layer becomes difficult, but also the adhesive layer becomes sticky, and it tends to be difficult to improve the delivery property of the film from the roll state.
Moreover, even if it mix | blends that content of tackifying resin is less than 5 weight%, it does not contribute to the adhesive force change of the adhesion layer, and the required adhesive force may not be obtained.
The content of the tackifier resin is preferably 6% by weight or more and less than 24% by weight, and more preferably 7% by weight or more and less than 23% by weight.

When the melt viscosity tends to decrease due to the addition of the tackifying resin in the adhesive layer, the polystyrene resin may be a block copolymer of styrene polymer block and butadiene polymer block, hydrogenated substance of styrene block and butadiene block. By adding about 1 wt% to 15 wt% by weight ratio to the mixture of the copolymer, it is possible to improve the melt viscosity difference between the substrate layer and the adhesive layer and to facilitate the lamination.
The blending amount of polystyrene resin at that time is preferably 5% by weight or more and 10% by weight or less.

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

  Moreover, the tackifying resin and the softener used in the adhesive layer are, depending on the type, a liquid or a powder, and some substances may contaminate the extruder at the time of extrusion. Such problems can be ameliorated by using a tackifier resin or a softener as a masterbatch with a polyethylene resin or a polyolefin resin, so that the tackifier resin or a softener can be used as a master resin with a polyethylene resin or a polyolefin resin. It is preferable to use it in

  The pressure-sensitive adhesive film of the present invention can also contain a polyolefin resin in the pressure-sensitive adhesive layer in order to improve the delivery property. The polyolefin resin is not particularly limited, and crystalline polypropylene, copolymer of propylene and a small amount of α-olefin, low density polyethylene, high density polyethylene, copolymer of ethylene and a small amount of α-olefin, ethylene and vinyl acetate And the like. Among them, many polyethylene resins have a low elastic modulus, and can be suitably used because they are easy to improve the unwinding property without reducing the adhesive strength.

The content of the polyolefin resin in the adhesive layer is 1 by weight ratio to the mixture of the hydrogenated substance of the block copolymer of styrene polymer block and butadiene polymer block and the random copolymer of styrene and butadiene. It is in the range of not less than 30% by weight.
When the content of the polyolefin-based resin exceeds 30% by weight, the adhesive strength may be lowered depending on the resin to be used, and a sufficient adhesive strength may not be obtained.
The content of the polyolefin resin is preferably mixed in a proportion of 25% by weight or less.

The pressure-sensitive adhesive film of the present invention can contain known additives as required. For example, a lubricant, an antiblocking agent, a heat stabilizer, an antioxidant, an antistatic agent, a light resistance agent, an impact modifier, etc. may be contained. However, these components have a relatively low molecular weight and may bleed out on the surface of the adhesive layer to reduce the adhesive strength of the adhesive layer. Therefore, when using an additive, it is preferable to make the low molecular weight substance on the adhesive layer surface less than 1 mg / m 2.
Here, the measurement of the low molecular weight substance on the surface of the adhesive layer was performed in the following procedure. After washing the surface of the adhesive layer with an organic solvent that does not corrode the resin that constitutes the adhesive layer, such as ethanol, the organic solvent is removed from the cleaning liquid by an evaporator or the like, and the residue is weighed to determine the adhesion It was divided by the surface area of the layer surface to obtain. Here, 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 adherend, which reduces the contact area and reduces the van der Waals force, so the adhesive strength is lowered. Not desirable. In the case of adding an additive, it is necessary to prevent migration and transfer to the adhesive layer by selecting an additive such as a polymer type or examining the amount and method of addition.

  The adhesive film and the adherend of the adhesive film of the present invention are preferably adhered to each other, and the peel strength of the end punched with a chisel is preferably in the range of 5 to 60 cN / 25 mm. When the peel strength exceeds 60 cN, when peeling the adhesive film from the optical member punched out with a mold, it may be difficult to grasp and peel off the end of the adhesive film. The lower limit of the peel strength is considered to be about 5 cN / 25 mm as a practical value. The upper limit is more preferably 50 cN / 25 mm.

The adhesive strength of the pressure-sensitive adhesive film of the present invention at 23 ° C. is preferably in the range of 150 to 800 g / 25 mm with respect to an acrylic plate, in consideration of use for various coatings. The acrylic board used for this evaluation uses what contains 88% or more of methacrylic resin. If the adhesive strength is less than 150 cN / 25 mm, depending on the cover, curling or the like may occur at the time of protection, and the function as a protective film may not be able to be carried out. On the other hand, when the adhesive strength exceeds 800 cN / 25 mm, there is a possibility that the film can not be peeled off smoothly when peeling the film from the coated body.
Moreover, it is preferable in consideration of use that it is a range of 1 to 20 cN / 25 mm with respect to a prism sheet at 23 ° C. If the adhesive strength is less than 1 cN / 25 mm, curling or the like occurs when protecting, and it can not bear the function as a protective film. On the other hand, when the adhesive strength exceeds 20 cN / 25 mm, when peeling off the adhesive film from the optical member punched out with a mold, it becomes difficult to grasp and peel off the end of the adhesive film, or punching with a mold Even if the film is peeled without peeling, there is a risk that the film can not be peeled smoothly. The adhesive force can be appropriately set by changing the resin composition, thickness and the like of the adhesive layer.

(Base material layer)
The pressure-sensitive adhesive film of the present invention requires a base layer mainly composed of a polypropylene-based resin, and as the polypropylene-based resin used here, crystalline polypropylene, random copolymerization of propylene and a small amount of α-olefin, block copolymer And the like. More specifically, n-heptane-insoluble isotactic propylene homopolymer or propylene containing 60% by weight or more of propylene used as a crystalline polypropylene resin in ordinary extrusion molding etc. And copolymers of propylene and other α-olefins, and copolymers of propylene homopolymers or copolymers of propylene and other α-olefins can be used alone or in combination.
The base layer preferably contains 60% by weight or more, and more preferably 70% by weight or more of a proprene unit. If the content of propylene is less than 60% by weight, the film may lose its feel and handling may be difficult. When the amount of propylene is less than 50% by weight or a polyethylene-based resin is used, the film becomes flexible and easily stretches, and even when the film is fed out, problems such as partial stretching and deformation of the film occur. It will be easier.
Here, n-heptane insolubility refers to the crystallinity of polypropylene and simultaneously indicates safety, and in the present invention, n-heptane insolubility according to Ministry of Health and Welfare notification No. 20, February 1982 (25 ° C., 60 ° C.) It is a preferred embodiment to use one that is compatible with an elution fraction of 150 pPm or less (a temperature exceeding 100 ° C. is 30 PPm or less) at the time of partial extraction.

As an α-olefin copolymer component of a copolymer of propylene and another α-olefin, α-olefins having 2 to 8 carbon atoms, such as ethylene or 1-butene, 1-pentene, 1-hexene, 4 -C4 or more alpha-olefins, such as-methyl 1-pentene, are mentioned. Here, the copolymer is preferably a random or block copolymer obtained by polymerizing propylene with one or more α-olefins exemplified above. 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, and more preferably in the range of 2.0 to 10.0 g / 10 min. Moreover, the copolymer of propylene and another alpha-olefin can also be used in mixture of 2 or more types.
Furthermore, it is also possible to re-granulate the scrap film that has come out during product processing of the film obtained in the present invention as a recovered raw material and add it to the base material layer. By using the recovered raw material, it is possible to reduce the production cost.

(Release layer)
The pressure-sensitive adhesive film of the present invention forms a release layer on the side opposite to the pressure-sensitive adhesive layer laminated on one side of the substrate layer, but doing so causes little blocking of the pressure-sensitive adhesive films even when the pressure-sensitive adhesive films are stacked. In particular, when the adhesive film is stored in a roll state and thereafter the film is fed out, problems such as partial elongation and deformation of the film hardly occur, and the film is excellent in processability. In order to prevent blocking of the pressure-sensitive adhesive films even when the pressure-sensitive adhesive films are overlapped, it is effective to form surface irregularities on the release layer and to reduce the contact area with the pressure-sensitive adhesive layer.

In order to form the surface irregularities as described above, a polypropylene resin may be mixed with a polypropylene resin such as a polyethylene resin or a polymethylpentene resin as a resin composition used for the adhesive layer. It is valid. By doing so, a layer having a rough surface can be formed in a mat-like manner.
In addition, by using a propylene-ethylene block copolymer as a polypropylene resin, the same effect can be expected without using an incompatible resin.
At this time, the content of the ethylene component in the propylene-ethylene block copolymer is preferably in the range of 3 to 18% by weight in terms of forming surface irregularities.
In addition, it is also possible to add resin incompatible with a propylene ethylene block copolymer.

  As resin incompatible with polypropylene resin, C4 or more alpha-olefin (co) polymers, such as low density polyethylene and 4-methyl pentene 1 type (co) polymer, are used suitably. Besides, linear 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, polyamide resin and the like are mentioned. Be In particular, the 4-methylpentene-1 (co) polymer not only roughens the surface in a mat-like manner, but also the improvement of releasability can be expected by lowering the surface free energy of the film surface.

  It is preferable that the peeling force with respect to the mold release surface of the adhesive surface of the adhesive film of this application is 200 cN / 40 mm or less in 23 degreeC from the point of the delivery property of the film at the time of making an adhesive film into a roll form. When the peeling force exceeds 200 cN / 40 mm, problems occur such as the film being partially stretched or deformed in the feeding of the film when the pressure-sensitive adhesive film is in a roll form. In addition, the lower limit of the peeling force with respect to the mold release surface of the adhesive surface of an adhesive film is about 1 cN / 40 mm as a realistic value, and also about 3 cN / 40 mm. The upper limit is more preferably 150 cN / 40 mm.

In view of the resin composition of the adhesive layer of the present invention, the three-dimensional average surface roughness SRa of the surface of the release layer is preferably 0.10 μm or more and 0.50 μm or less. By doing so, the blocking resistance and the protective performance of the coating can be improved. When the surface roughness of the release layer is lower than 0.10 μm, the feeding property of the film 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 adhesion may be significantly reduced. At this time, it is more preferable that the surface asperities of the release layer have a surface having an average surface roughness SRa of 0.25 μm or more and 0.45 μm or less.
In addition, three-dimensional average surface roughness SRa of the mold release layer surface means the average roughness in the center plane at the time of approximating a surface roughness curve by a sine curve, and it can measure it with a surface roughness measuring apparatus etc.

It is preferable that the thickness of the adhesion layer of this invention is 2 micrometers or more and less than 20 micrometers. When the thickness of the adhesive layer is less than 2 μm, stable film formation by co-extrusion becomes difficult, and when it is 20 μm or more, the film becomes disadvantageous in cost.
At this time, in the case of increasing the adhesive strength, it is preferable to increase the thickness in consideration of the viscosity. By increasing the thickness of the adhesive layer, the contact area with the adherend tends to be large. The thickness of the adhesive layer is preferably 3 μm or more and 15 μm or less, and more preferably 4 μm or more and 10 μm or less.

  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 less than 75 μm, and still more preferably 15 μm or more and less than 40 μm. When the thickness of the base layer is less than 5 μm, the feeling of stiffness is weakened, and when it is attached to a cover as a protective film, wrinkles etc. are easily included, and there is a problem that sufficient adhesive strength can not be obtained. If it is above, it will be a disadvantageous film in terms of cost.

The thickness of the release layer of the present invention is preferably 2 μm or more and less than 30 μm. When the thickness of the adhesive film is less than 1 μm, stable film formation by coextrusion becomes difficult, and when it is 30 μm or more, the film becomes disadvantageous in 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 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 still more preferably 20 μm or more and 100 μm or less. When the total thickness of the film is too thin, the handling may be poor, and when it is too thick, the rigidity may be high and the handling may be poor, and the film may be disadvantageous in cost.
The self-adhesive surface protective film of the present invention is composed of a base layer containing the above resin component, an adhesive layer and a release layer, and the resin constituting each layer is, for example, a uniaxial or biaxial extruder. It is obtained by being fed to a feed block type or multi manifold type T die as it is in a molten state and laminated and extruded with three or more layers. The temperature of the extruder of each layer may be appropriately adjusted in consideration of the molding temperature of the components used in each layer, for example, in the range of 200 ° C. to 260 ° C., in order to bring each layer into a molten state. It is also good. The temperature of the T-die may be similar to the above temperature.

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 in terms of ease of handling, the width is generally 1600 mm or less in general, and the winding length is preferably 5000 m or less when the film thickness is 40 μm. Also, as the winding core, a plastic core or metal core such as 3 inches, 6 inches, 8 inches, etc. can usually be used.
Moreover, it is preferable that it is a film roll wound up with the dimension of length 100 m or more and width 450 mm or more from the suitability of processing.

  The pressure-sensitive adhesive film of the present invention protects members such as a prism sheet used in optical applications from being damaged when stacked, stored, transported, or transported in a manufacturing process. And can be used to protect against damage during secondary processing (e.g., bending or pressing) of the article.

  The invention will now be further described by way of example. However, the present invention is not limited to the following examples without departing from the scope of the invention. In addition, the evaluation method of the physical property in a following example and a comparative example is as follows.

(1) Adhesive force It measured by the following method based on JIS-Z-0237 (2000) adhesive tape and adhesive sheet test method.
As an adherend, acrylic plate (Mitsubishi Rayon Co., Ltd .: Acrilite 3 mm thick) 50 mm × 150 mm, prism sheet (lens part consists of triangular prism, height of triangular prism is 25 μm, width of triangular prism is 50 μm) 50 mm × 150 mm Prepare a test piece of 150 mm in the winding direction at the time of film production, and cut out a 25 mm test piece in the direction orthogonal to that as a rubber strip (a rubber layer with a mass of 2000 g (spring hardness 80 Hs on roller surface, 6 mm thickness) The adherend and the test piece were crimped while making one reciprocation at a speed of 5 mm / sec using a 45 mm wide and 95 mm diameter (including rubber layer) coat. After pressure bonding, it was left for 30 minutes in an environment with a temperature of 23 ° C and a relative humidity of 65%, and peeled off 180 degrees at a speed of 300 mm / minute using "Autograph" (AGS-J) manufactured by Shimadzu Corporation. The maximum resistance at that time was taken as the adhesive strength [cN / 25 mm]. The 180 degree peeling means that the peeling angle of the acrylic plate and the film at the time of measuring the resistance value at the time of peeling is maintained at 180 degrees.
In the case of measurement, prepare a polyester sheet with a thickness of 190 μm and a size of 25 mm × 170 mm as a grip for the measurement sample, and the adhesive film side of the measurement sample where the adhesive film and acrylic plate are crimped It stuck on cellophane tape, and was used as a grip margin at the time of measurement. A schematic view of the measurement sample is shown in FIG. The measurement was performed 3 times for one sample, and the average value was taken as the adhesion of the sample.

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

(3) Measurement of Styrene Component in Styrene-Based Elastomer Approximately 330 mg of a resin sample was dissolved in deuterated chloroform and C-NMR (manufactured by BRUKER, AVANCE 500) was measured. From the obtained measurement results, the amount of styrene component in the styrene elastomer was identified.

(4) Peeling force Acrylic board (Mitsubishi Rayon Co., Ltd .: Acrelite 3 mm thick) 50 mm x 150 mm Double-sided adhesive tape (Nitto Denko Co., Ltd .: No. 535A) is attached to the entire surface, and other side of double-sided adhesive tape The test piece of 150 mm (the winding direction at the time of film production) × 50 mm (the orthogonal direction to the winding direction at the time of film production) was pasted so that the adhesive surface of the test piece came.
As a new test piece, a test piece of 150 mm in the winding direction at the time of film production and 40 mm in the direction perpendicular thereto is cut out, and the release surface of the test piece attached to the adhesive surface and acrylic plate via double-sided adhesive tape After superposing, using a rubber roll with a mass of 2000 g (spring hardness of 80 Hs on the roller surface, covered with a rubber layer with a thickness of 6 mm, with a width of 45 mm and a diameter of 95 mm including a rubber layer), And the test piece were crimped while making one reciprocation at a speed of 5 mm / sec.
After crimping, apply a load of 60 Kg to a total area of 4000 mm2 of 100 mm in the winding direction, 100 mm in the winding direction and 40 mm in the direction orthogonal to it, leave for 24 hours under an environment of 40 ° C. and 65% relative humidity and then cool down to 23 ° C. This was carried out by peeling 180 degrees at a speed of 300 mm / min using “Autograph” (AGS-J) manufactured by Shimadzu Corporation. For measurement, 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 stick it on the end of the 150 mm × 40 mm test piece with a cellophane tape with a width of 15 mm. It was the grip of the occasion. The measurement made the average value of the resistance value at the time of peeling off from 40 mm to 60 mm in the crimped part 100 mm of the test piece as the peeling force [cN / 40 mm] of the test piece. The measurement was carried out three times, and the average value was taken as the final peeling force.

(5) Peelability of adhesive film from prism sheet, peel strength Prism sheet (The lens part is a triangular prism, the height of triangular prism is 25 μm, the width of triangular prism is 50 μm) Prepare 25 mm × 150 mm as a test piece A test roll of 150 mm in the winding direction at the time of manufacture and 25 mm in the direction orthogonal to that is cut out, and a rubber roll with a mass of 2000 g (spring hardness 80 Hs on roller surface, covered with rubber layer 6 mm thick, width 45 mm, diameter The adherend and the test piece were crimped by causing one reciprocation at a speed of 5 mm / sec using a material of 95 mm (including a rubber layer). This sample was punched at 90 ° using a chasing chisel (manufactured by Yosuke Toki Kogyo Co., Ltd., blade width 42 mm) and a shockless hammer (manufactured by Ohetch Industrial Co., Ltd., OS-20).
With regard to the punched end, the ease of peeling when manually peeling the space between the prism sheet and the film was evaluated. Those that could be easily peeled off were marked ○ (good), and those that were particularly easy to peel off were marked ◎ (very good), and those that were difficult to peel easily by hand were marked x (defect).
In addition, a cellophane tape is attached to the punched end to make a grip, and using “Autograph” (AGS-J) manufactured by Shimadzu Corporation, the peak value of the strength when pulled at a speed of 300 mm / min. [CN / 40 mm] was measured. The measurement was carried out three times, and the average value was taken as the final peel strength. A schematic diagram of the measurement is shown in FIGS.

(6) Delivery from Roll After obtaining a 550 mm wide, 500 m wound body with a slit, it was stored in a rolled state for 7 days under a light shielding environment at a temperature of 23 ° C. and a humidity of 75%. Immediately after the film roll after storage was rewound 300 m on another plastic core (diameter 9 cm), the end of the film was held by hand and pulled, and 3 m was rewound. It was visually confirmed whether the film had partial elongation, deformation or stop marks when it was rewound. Those with no partial elongation, deformation, or stopping mark were evaluated as ((good), and those with partial elongation, deformation, or stopping mark were evaluated as x (defect).

Example 1
(Creating a substrate layer)
100% by weight of a homopolypropylene resin (manufactured by Sumitomo Chemical Co., Ltd .: FLX 80E4, 230 ° CMFR: 7.5 g / 10 min) was melt-extruded at 240 ° C. with a 90 mm φ single-screw extruder to form a base layer.
(Creation of adhesive layer)
Hydrogenated product of block copolymer of styrene polymer block and butadiene polymer block (Asahi Kasei Chemicals: Tuftec H1221, 12 wt% of styrene component ratio, 230 ° CMFR: 4.5 g / 10 min) and 30 wt% of styrene 55 wt% of a hydrogenated product of a random copolymer of ethylene and butadiene (manufactured by Asahi Kasei Chemicals: S.O.E.L. 606, styrene component ratio 46 wt%, MFR: 2.9 g / 10 min) and petroleum resin (Arakawa Chemical Co .: Alcon P125 (15% by weight) was melt-extruded at 210 ° C. in a 40 mmφ single-screw extruder to form an adhesive layer.
(Create release layer)
90% by weight of a propylene-ethylene block copolymer (manufactured by Japan Polypropylene: BC3HF) and 10% by weight of a low density polyethylene resin (manufactured by Ube Industries, Ltd .: R300) were melt-extruded at 230 ° C. .
(Creation of film)
Perform lamination extrusion within a three-layer T-die (feed block type, lip width 850 mm, lip gap 1 mm) at 245 ° C while the base material layer, adhesive layer and release layer are each melted in each extruder The The extruded film is pulled to a casting roll at a temperature of 30 ° C. at a speed of 20 m / min, and solidified by cooling to a substrate layer thickness of 30 μm, adhesive layer thickness of 5 μm, release layer thickness of 5 μm, film width of 600 mm, film length A three-kind three-layer unstretched film of 1100 m was obtained. Further, this film is slit at a speed of 50 m / min with a take-up tension of 40 N and a contact pressure of 50 N against the film width by a rubber roll to obtain an unstretched film having a film width of 550 mm and a film length of 500 m. Obtained.

Example 2
The base material layer and the release layer were the same as in Example 1, and the adhesive layer was changed to the following contents to obtain an unstretched film of 3 types and 3 layers in the same manner as in Example 1.
(Creation of adhesive layer)
Hydrogenated product of block copolymer of styrenic polymer block and butadiene polymer block (Asahi Kasei Chemicals: Tuftec H1221, 12 wt% of styrene component ratio, 230 ° CMFR: 4.5 g / 10 min) 10 wt% and styrene A hydrogenated product of a random copolymer of ethylene and butadiene (manufactured by Asahi Kasei Chemicals: S.O.E.L. 606, styrene component ratio 46% by weight, MFR: 2.9 g / 10 min) and 80% by weight and petroleum resin (Arakawa Chemical Co .: 10% by weight of Alcon P125) was melt-extruded at 210 ° C. in a 40 mmφ single-screw extruder to form an adhesive layer.

[Example 3]
The base material layer and the release layer were the same as in Example 1, and the adhesive layer was changed to the following contents to obtain an unstretched film of 3 types and 3 layers in the same manner as in Example 1.
(Creation of adhesive layer)
Hydrogenated product of block copolymer of styrene polymer block and butadiene polymer block (Asahi Kasei Chemicals: Tuftec H1221, 12 wt% of styrene component ratio, 230 ° CMFR: 4.5 g / 10 min) and 5 wt% of styrene A hydrogenated product of a random copolymer of ethylene and butadiene (manufactured by Asahi Kasei Chemicals: S.O.E.L. 606, styrene component ratio 46% by weight, MFR: 2.9 g / 10 min) and 80% by weight and petroleum resin (Arakawa Chemical Co .: Adhesive adhesion by melt extrusion of Alcon P 125) 10% by weight and ethylene-α-olefin copolymer (Sumitomo Chemical Co .: CX 3007, 190 ° CMFR: 3.7 g / 10 min) at 210 ° C. using a 40 mm single screw extruder It was a layer.

Example 4
The base layer is the same as Example 1, and the adhesive layer and the release layer are changed to the following contents, the base layer thickness is 25 μm, the adhesive layer thickness is 10 μm, and the release layer thickness is 5 μm. An unstretched film of 3 types and 3 layers was obtained in the same manner as in the above.
(Creation of adhesive layer)
Hydrogenated product of block copolymer of styrene polymer block and butadiene polymer block (manufactured by Asahi Kasei Chemicals: Tuftec H1221, 12 wt% of styrene component ratio, 230 ° CMFR: 4.5 g / 10 min) and 50 wt% of styrene Hydrogenated product of random copolymer of ethylene and butadiene (manufactured by Asahi Kasei Chemicals: S.O.E.L.606, styrene component ratio 46 wt%, MFR: 2.9 g / 10 min) and 15 wt% petroleum resin (Arakawa Chemical Co .: Glucon is extruded by melt extruding 15% by weight of Alcon P125 and 20% by weight of ethylene-α-olefin copolymer (manufactured by Sumitomo Chemical Co., Ltd .: CX 3007, 190 ° CMFR: 3.7 g / 10 min) at 210 ° C. It was a layer.
(Create release layer)
90 wt% of a propylene-ethylene block copolymer (manufactured by Nippon Polypropylene: BC3HF) and 10 wt% of a polymethylpentene resin (manufactured by Mitsui Chemicals, Ltd .: RT31) were melt-extruded at 250 ° C. by a 65 mm φ single-screw extruder to form a release layer.

Comparative Example 1
The base material layer and the release layer were the same as in Example 1, and the adhesive layer was changed to the following contents to obtain an unstretched film of 3 types and 3 layers in the same manner as in Example 1.
(Creation of adhesive layer)
Hydrogenated product of block copolymer of styrene polymer block and butadiene polymer block (Asahi Kasei Chemicals: Tuftec H1221, 12 wt% of styrene component ratio, 230 ° CMFR: 4.5 g / 10 min) 40 wt% and styrene Hydrogenated product of random copolymer of ethylene and butadiene (manufactured by Asahi Kasei Chemicals: S.O.E.L.606, styrene component ratio 46 wt%, MFR: 2.9 g / 10 min) and 15 wt% petroleum resin (Arakawa Chemical Co .: Glucon is extruded by melt-extruding 10% by weight of Alcon P 125) and 35% by weight of ethylene-α-olefin copolymer (Sumitomo Chemical Co .: CX 3007, 190 ° CMFR: 3.7 g / 10 min) at 210 ° C. in a 40 mm φ single-screw extruder It was a layer.

Comparative Example 2
The base material layer and the release layer were the same as in Example 1, and the adhesive layer was changed to the following contents to obtain an unstretched film of 3 types and 3 layers in the same manner as in Example 1.
(Creation of adhesive layer)
Hydrogenated product of block copolymer of styrenic polymer block and butadiene polymer block (Asahi Kasei Chemicals: Tuftec H1221, 12 wt% of styrene component ratio, 230 ° CMFR: 4.5 g / 10 min) 10 wt% and styrene And butadiene random copolymer hydrogenated product (JSR product: Dynaron 1320P, styrene component ratio 10% by weight, 230 ° CMFR: 3.5 g / 10 min) 80% by weight and petroleum resin (Arakawa Chemical product: Alcon P 125) 10 A weight% was melt extruded at 210 ° C. with a 40 mmφ single screw extruder to form an adhesive layer.

Comparative Example 3
The base material layer and the release layer were the same as in Example 1, and the adhesive layer was changed to the following contents to obtain an unstretched film of 3 types and 3 layers in the same manner as in Example 1.
(Creation of adhesive layer)
Hydrogenated product of block copolymer of styrene polymer block and butadiene polymer block (Asahi Kasei Chemicals: Tuftec H1221, 12 wt% of styrene component ratio, 230 ° CMFR: 4.5 g / 10 min) and 30 wt% of styrene Hydrogenated substance of random copolymer of butadiene and butadiene (JSR product: Dynaron 1320P, styrene component ratio 10 wt%, 230 ° CMFR: 3.5 g / 10 min) 55 wt% and petroleum resin (Arakawa Chemical product: Alcon P 125) 15 A weight% was melt extruded at 210 ° C. with a 40 mmφ single screw extruder to form an adhesive layer.

Comparative Example 4
The base material layer and the release layer were the same as in Example 1, and the adhesive layer was changed to the following contents to obtain an unstretched film of 3 types and 3 layers in the same manner as in Example 1.
(Creation of adhesive layer)
Hydrogenated product of block copolymer of styrene polymer block and butadiene polymer block (Asahi Kasei Chemicals: Tuftec H1221, 12 wt% of styrene component ratio, 230 ° CMFR: 4.5 g / 10 min) 70 wt% and styrene Hydrogenated product of random copolymer of ethylene and butadiene (manufactured by Asahi Kasei Chemicals: S.O.E.L. 606, styrene component ratio 46 wt%, MFR: 2.9 g / 10 min) and 20 wt% petroleum resin (Arakawa Chemical Co., Ltd.) 10% by weight of Alcon P125) was melt-extruded at 210 ° C. in a 40 mmφ single-screw extruder to form an adhesive layer.

Comparative Example 5
The base layer and the pressure-sensitive adhesive layer were the same as in Example 1, and the release layer was changed to the following contents to obtain an unstretched film of three types and three layers in the same manner as in Example 4.
(Create release layer)
100% by weight of a homopolypropylene resin (manufactured by Sumitomo Chemical Co., Ltd .: FLX 80E4, 230 ° CMFR: 7.5 g / 10 min) was melt-extruded at 240 ° C. with a 65 mm φ single-screw extruder to form a base layer.

The results are shown in Tables 1 and 2.

  As is clear from Table 1, the films obtained in Examples 1 to 5 have a peeling strength that causes no problem in practical use when used as a protective film, and the feeding properties when the film is drawn out as a roll are also good. The

  On the other hand, the film obtained in Comparative Example 1 had high peel strength, and the peelability of the pressure-sensitive adhesive film after punching with a mold was not good. The films obtained in Comparative Examples 2 and 3 and 4 and 5 had no problem in peel strength, but the peel force was large, and it could not be said that the feeding property when the film was drawn out as a roll was good. Thus, the films obtained in the comparative examples were all inferior in quality and low in practicality.

Claims (4)

An adhesive layer on one surface of a substrate layer made of a polypropylene resin, we are laminated by co-extruding a release layer on the opposite surface,
The adhesive layer is a hydrogenated product of a block copolymer of a styrene polymer block and a butadiene polymer block, and the weight ratio of the styrene component is 5% by weight or more and 40% by weight or less. A styrene-based elastomer B, which is a hydrogenated product of a random copolymer of vinyl and butadiene, and the weight ratio of the styrene component is 40% by weight or more and 70% by weight or less, and a tackifying resin,
The release layer contains a propylene-ethylene block copolymer,
The adhesive film and the adherend are pasted together, the peeling strength of the end punched out with a chisel is 60 cN / 25 mm or less, and the peeling force of the adhesive layer surface to the release layer surface is 200 cN / 40 mm or less. Self-adhesive surface protection film.   The self-adhesive polypropylene-based film according to claim 1, wherein the melt flow rate (MFR: 230 ° C, 2.16 Kgf) of the styrenic elastomer in the adhesive layer is 0.5 to 8 g / 10 min.   The melt flow rate (MFR: 230 ° C., 2.16 Kgf) of the polypropylene-based resin in the substrate layer is 1.0 to 15 g / 10 min, The self-adhesive polypropylene system according to any one of claims 1 to 2 the film   The self-adhesive polypropylene film according to any one of claims 1 to 3, wherein the resin used for the release layer is a non-silicon resin.