WO2015194059A1

WO2015194059A1 - Self-adhesive surface-protection film

Info

Publication number: WO2015194059A1
Application number: PCT/JP2014/077435
Authority: WO
Inventors: 茂知山本; 大木　祐和; 松田　明
Original assignee: 東洋紡株式会社
Priority date: 2014-06-18
Filing date: 2014-10-15
Publication date: 2015-12-23
Also published as: JPWO2015194059A1; CN106459684A; TW201600576A; KR20170021784A; JP6515917B2; KR102279434B1; TWI637035B; CN106459684B

Abstract

Provided is a self-adhesive surface-protection film which exhibits excellent film processability, with which an end of an adhesive film can be easily grasped and peeled off when peeling the adhesive film from an optical member punched by a die, and with which problems such as partial elongation and deformation of the film do not readily occur even when the adhesive film is stored in a rolled state, and subsequently withdrawn. This self-adhesive surface-protection film is characterized by being obtained by using co-extrusion to stack an adhesive layer on one surface of a base material layer comprising a polypropylene-based resin, and a release layer on the opposite surface of the base material layer. The self-adhesive surface-protection film is further characterized in that: the adhesive film is bonded to an adherend; the peeling strength of an end punched by a chisel is not more than 60 cN/25mm; and the adhesive surface has a peeling force with respect to the release surface of not more than 200 cN/40 mm.

Description

Self-adhesive surface protective film

The present invention relates to an adhesive film. The adhesive film of the present invention protects members such as prism sheets used for optical applications from being damaged when stacked, stored, transported, or transported in the manufacturing process. Can be suitably used.

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

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

In order to increase the adhesive strength of the adhesive layer, it is possible to use a styrene-based elastomer that exhibits high adhesive strength as a main component, but if the adhesive strength of the adhesive layer is increased, the film is stored in a roll state. Then, when the film is subsequently fed out, blocking occurs between the pressure-sensitive adhesive layer and the film surface on the opposite side of the pressure-sensitive adhesive layer, causing problems such as partial elongation or deformation of the film. Further, when the blocking is severe, there is a problem in that the feeding sound becomes large when the film is fed and the surrounding working environment is remarkably deteriorated as noise.

When creating an adhesive film by melt-extrusion of the entire film layer, as a countermeasure, fluorine-based resin, silicon-based resin (see, for example, Patent Documents 1 and 2) or saturated fatty acid bisamide is used for the base layer. (For example, refer to Patent Document 3 etc.) has been studied, but any of these resins may migrate to the adhesive layer when stored in a roll state, and the adhesive strength is reduced. Concerns such as letting it go and contaminating the covering cannot be wiped off.

In addition, the use of a styrene-based elastomer for the adhesive layer has also been studied (see, for example, Patent Documents 4, 5, 6, etc.). Neither of the above-mentioned problems in feeding the film was satisfied.

On the other hand, it has been proposed to produce an optical member by punching out a long sheet obtained by sticking an adhesive film to the prism sheet with a mold (see Patent Document 7). When peeling an adhesive film from an optical member punched with a mold, the edge of the adhesive film is grasped and peeled off. However, if punching is performed with a mold, the adhesive film and the prism sheet may be difficult to peel off. .
The phenomenon described above occurs when the pressure-sensitive adhesive layer of the pressure-sensitive adhesive film bites into the concave and convex portions of the prism sheet by punching, and the end portion is extremely difficult to peel off.

As the above countermeasure, an adhesive layer containing a styrene elastomer as a main raw material and containing an imine compound and a fatty acid amide has been proposed (see Patent Document 8, etc.). There is a possibility that these resins may migrate, and concerns such as a decrease in adhesive strength and contamination of the covering cannot be wiped off.

JP 2008-81589 A JP 2008-308559 A Japanese Patent No. 4565058 Japanese Patent Laid-Open No. 08-73822 Japanese Patent Laid-Open No. 2007-161882 JP 2007-332329 A JP 2007-187781 A JP 2012-1117013 A

The problem to be solved by the present invention is that when peeling an adhesive film from an optical member punched with a mold, it is easy to grasp and peel off the end of the adhesive film, and store the adhesive film in a roll state. Then, also when the film is fed out, it is an object of the present invention to provide a self-adhesive surface protective film that is less prone to problems such as partial stretching or deformation of the film and that is excellent in processability of the film.

As a result of intensive studies, the present inventors have found that the above problems can be solved, and have reached the present invention.
That is, in the present invention, an adhesive layer is laminated on one side of a base material layer made of polypropylene resin, and a release layer is laminated on the opposite side by coextrusion, and the adhesive film and the adherend are bonded together and punched with fleas. A self-adhesive surface protective film, wherein 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 an adhesive film from an 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 state, and then remove the film. Even when the film is fed, a self-adhesive surface protective film excellent in processing suitability of the film can be obtained because the film is not easily stretched or deformed.

In this case, the melt flow rate (MFR: 230 ° C., 2.16 Kgf) of either the styrene elastomer A or the styrene elastomer B in the previous adhesion layer is 0.5 to 8 g / 10 min. Is preferred.

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

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 grasp and peel off the edge of the pressure-sensitive adhesive film when peeling the pressure-sensitive adhesive film from the optical member punched with a mold, and then store the pressure-sensitive adhesive film in a roll state, and then the film Also when the film is fed out, there is an advantage that problems such as partial stretching or deformation of the film hardly occur, and the processability of the film is excellent.

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, and a release layer is laminated on the opposite side by coextrusion, and the adhesive film and the adherend are bonded together and punched with fleas. The self-adhesive surface protective film has a peel strength of 60 cN / 25 mm or less and a peel strength of the adhesive surface to the release surface of 200 cN / 40 mm or less.
Hereinafter, embodiments of the pressure-sensitive adhesive film of the present invention will be described.

(Adhesive layer)
As the resin constituting the pressure-sensitive adhesive layer of the present invention, when peeling the pressure-sensitive adhesive film from the optical member punched with a mold, it is easy to grasp and peel off the edge of the pressure-sensitive adhesive film, and store the pressure-sensitive adhesive film in a roll state In order to prevent problems such as partial stretching or deformation of the film even when the film is subsequently fed out, a styrene-based elastomer is preferably used. In particular, it is preferable to use at least two types of styrenic elastomers having different compositions from the viewpoint of satisfying film characteristics. In order to control the adhesive force, an olefin resin such as a polyethylene resin, a tackifier resin, a softening agent, polystyrene, and the like can be mixed as necessary.

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

The total amount of the styrene-based elastomer in the adhesive layer is 60% by weight with respect to the entire resin composition constituting the adhesive layer in order to express the ease of peeling from the optical member after punching and the roll-out property of the film from the roll state. As mentioned above, it is preferable that it is 99 weight% or less. When the weight ratio with respect to the entire resin composition constituting the adhesive layer is less than 60% by weight, the adhesive strength is lowered, and it becomes difficult to obtain the required adhesive strength. The total amount of styrene-based elastomer in the adhesive layer is preferably in the range of 65% by weight to 95% by weight.

Further, hydrogen of a styrene polymer block and a butadiene polymer block copolymer in a mixture of a hydrogenated product of a block copolymer of a styrene polymer block and a butadiene polymer block and a random copolymer of styrene and butadiene. The weight ratio of the additive is preferably 5% by weight or more. When the weight ratio of the hydrogenated product of the block copolymer of the styrene polymer block and the butadiene polymer block is less than 5% by weight, the adhesive strength is lowered, and it becomes difficult to obtain the required adhesive strength.
The weight ratio of the hydrogenated product of the styrene polymer block and 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 product of the block copolymer of the styrene polymer block and the butadiene polymer block is preferably 80% by weight or less. When the weight ratio of the styrene polymer block and the hydrogenated butadiene polymer block copolymer is more than 80% by weight, the roll-out property from the roll state may not be sufficiently exhibited.
The weight ratio of the hydrogenated styrene polymer block to the butadiene polymer block copolymer is more preferably 60% by weight or less, and particularly preferably 40% by weight or less.

Of the styrene elastomer used, the weight ratio of the styrene component in the hydrogenated block copolymer of the styrene polymer block and the butadiene polymer block is preferably 5% by weight or more and 40% by weight or less. .
If the weight ratio of the styrene component is less than 5% by weight, granulation at the time of preparing the resin becomes difficult, and if it exceeds 40% by weight, adhesion with a hydrogenated product of a random copolymer of styrene and butadiene will result in adhesion. It becomes difficult to obtain the required 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, the weight ratio of the styrene component in the styrene elastomer of the hydrogenated random copolymer of styrene and butadiene is preferably 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 roll-out property of the film from the roll state may not be sufficiently expressed, and when it exceeds 70% by weight, the adhesive strength is lowered and the required adhesive strength is obtained. 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, and rosin resins. The molecular weight of the tackifying resin is not particularly limited and can be set appropriately.However, if the molecular weight is small, there is a risk of causing material transfer from the adhesive layer to the adherend or heavy peeling, while the molecular weight is large. Therefore, the number-average molecular weight of the tackifier resin is preferably about 1,000 to 100,000. The number average molecular weight can be measured by gel permeation chromatography or the like.

The content of the tackifying resin in the resin composition constituting the adhesive layer is preferably a mixture of a hydrogenated product of a block copolymer of a styrene polymer block and a butadiene polymer block and a random copolymer of styrene and butadiene The weight ratio is 5% by weight or more and less than 25% by weight.
When the content of the tackifying resin exceeds 25% by weight, the melt viscosity of the tackifying resin is extremely low due to its low molecular weight, and the main component is a polypropylene resin when performing coextrusion film formation using a T-die or the like. In addition to the difficulty of lamination with the base material layer, the adhesive layer becomes sticky, and the film feedability from the roll state tends to be difficult to improve.
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 an adhesion layer, and the required adhesive force may not be obtained.
The content of the tackifying resin is preferably 6% by weight or more and less than 24% by weight, more preferably 7% by weight or more and less than 23% by weight.

If the melt viscosity tends to decrease due to the addition of tackifying resin in the adhesive layer, the polystyrene resin can be a randomized styrene and butadiene hydrogenated block copolymer of styrene polymer block and butadiene polymer block. By adding about 1% by weight to 15% by weight with respect to the copolymer mixture, the melt viscosity difference between the base material layer and the adhesive layer can be improved, and lamination can be facilitated.
The amount of polystyrene resin at that time is preferably 5% by weight or more and 10% by weight or less.

Examples of the softening agent include low molecular weight diene polymers, polyisobutylene, hydrogenated polyisoprene, hydrogenated polybutadiene and derivatives thereof, and polybutene. The molecular weight of the softening agent is not particularly limited and can be set appropriately, but if the molecular weight is small, there is a risk of causing material transfer from the adhesive layer to the adherend or heavy peeling, while the molecular weight is large. The number average molecular weight of the softening agent is preferably 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.

Also, the tackifying resin and softening agent used in the adhesive layer are liquids or powders depending on the type, and there are things that contaminate the extruder during extrusion. Such problems can be improved by using a tackifier resin or softener as a masterbatch with a polyethylene resin or polyolefin resin, so that the tackifier resin or softener can be a masterbatch with a polyethylene resin or polyolefin resin. It is more preferable to use it after making it.

The pressure-sensitive adhesive film of the present invention may contain a polyolefin resin in the pressure-sensitive adhesive layer in order to improve the drawability. Polyolefin-based resin is not particularly limited, 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 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 feeding property without reducing the adhesive force.

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

The pressure-sensitive adhesive film of the present invention can contain known additives as necessary. For example, a lubricant, an antiblocking agent, a heat stabilizer, an antioxidant, an antistatic agent, a light resistance agent, an impact resistance improvement agent and the like may be contained. However, these components have a relatively low molecular weight, and may bleed out to the surface of the adhesive layer to reduce the adhesive strength of the adhesive layer. Therefore, when an additive is used, the low molecular weight substance on the surface of the adhesive layer is preferably less than 1 mg / m2.
Here, the measurement of the low molecular weight substance on the surface of the adhesive layer was carried out by the following procedure. After the surface of the adhesive layer is washed with an organic solvent that does not erode the resin constituting the adhesive layer such as ethanol, the organic solvent is removed from the cleaning solution with an evaporator, and the residue obtained by weighing the residue is washed. It was obtained by dividing by the surface area of the layer surface. Here, if the residue is present at 1 mg / m 2 or more, foreign matter exists between the surface of the adhesive layer and the adherend surface, which reduces the contact area and lowers the van der Waals force. It is not preferable. In the case of adding an additive, it is necessary to select an additive such as a polymer type or to examine the addition amount and the addition method so that there is no transfer or transfer to the adhesive layer.

In the pressure-sensitive adhesive film of the present invention, the peel strength at the end of the pressure-sensitive adhesive film bonded to the adherend and punched with a chisel is preferably in the range of 5 to 60 cN / 25 mm. If the peel strength exceeds 60 cN, it may be difficult to grasp and peel off the end portion of the adhesive film when the adhesive film is peeled from the optical member punched with a mold. 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 pressure-sensitive adhesive strength of the pressure-sensitive adhesive film of the present invention is preferably in the range of 150 to 800 g / 25 mm with respect to the acrylic plate at 23 ° C. in consideration of use in various coverings. The acrylic board used for this evaluation uses what contains methacrylic resin 88% or more. When the adhesive strength is less than 150 cN / 25 mm, turning may occur when protecting depending on the covering, and the function as a protective film may not be carried. On the other hand, when the adhesive strength exceeds 800 cN / 25 mm, there is a possibility that the film cannot be smoothly peeled when the film is peeled from the covering.
Further, at 23 ° C., the range of 1 to 20 cN / 25 mm with respect to the prism sheet is preferable in consideration of use. When the adhesive strength is less than 1 cN / 25 mm, turning or the like occurs when protecting, and the function as a protective film cannot be carried. On the other hand, when the adhesive strength exceeds 20 cN / 25 mm, when peeling the adhesive film from the optical member punched by the mold, it becomes difficult to grasp the edge of the adhesive film and peel it off, Even if the film is peeled off without smooth, there is a possibility that it cannot be peeled off smoothly. The adhesive force can be appropriately set by changing the resin composition, thickness, etc. of the adhesive layer.

(Base material layer)
The pressure-sensitive adhesive film of the present invention requires a base material layer mainly composed of a polypropylene-based resin. The polypropylene-based resin used here includes crystalline polypropylene, random copolymerization of propylene and a small amount of α-olefin, and block copolymerization. More specifically, as a crystalline polypropylene resin, an n-heptane-insoluble isotactic propylene homopolymer used in ordinary extrusion molding or the like or propylene containing 60% by weight or more of propylene And other α-olefin copolymers. These propylene homopolymers or copolymers of propylene and other α-olefins can be used alone or in admixture.
The base material layer preferably contains 60% by weight or more of propylene units, more preferably 70% by weight or more. If the propylene content is less than 60% by weight, the film may lose a feeling of back and handling may be difficult. In addition, when the propylene content is less than 50% by weight or a polyethylene resin is used, the film becomes flexible and easily stretched, and problems such as partial stretching or deformation of the film occur when the film is fed out. It becomes easy.
Here, the insolubility of n-heptane is indicative of the crystallinity of polypropylene and at the same time indicates safety. In the present invention, n-heptane insolubility (at 25 ° C., 60 ° C. according to Ministry of Health and Welfare Notification No. 20 in February 1982). It is a preferred embodiment to use one that is compatible with an elution amount of 150 pPm or less (if the operating temperature exceeds 100 ° C., 30 PPm or less) at the time of partial extraction.

The α-olefin copolymerization component of the copolymer of propylene and other α-olefins includes α-olefins having 2 to 8 carbon atoms such as ethylene, 1-butene, 1-pentene, 1-hexene, 4 -C4 or higher α-olefins such as methyl-1-pentene. Here, the copolymer is preferably a random or block copolymer obtained by polymerizing one or more of the α-olefins exemplified above with propylene. The melt flow rate (MFR: 230 ° C., 2.16 Kgf) of the polypropylene resin used is preferably in the range of 1.0 to 15 g / 10 minutes, more preferably in the range of 2.0 to 10.0 g / 10 minutes. Further, two or more kinds of copolymers of propylene and other α-olefins can be mixed and used.
Furthermore, the waste film produced when the film obtained in the present invention is processed into a product can be re-granulated as a recovered raw material and added to the base material layer. By using the recovered raw material, the production cost can be reduced.

(Release layer)
The pressure-sensitive adhesive film of the present invention forms a release layer on the surface opposite to the pressure-sensitive adhesive layer laminated on one side of the base material layer, so that even if the pressure-sensitive adhesive films are stacked, there is little blocking between the pressure-sensitive adhesive films, In particular, when the pressure-sensitive adhesive film is stored in a roll state and then fed out, problems such as partial stretching or deformation of the film hardly occur, and the film has excellent workability. In order to prevent blocking of the adhesive films even when the adhesive films are stacked, it is effective to form surface irregularities on the release layer to reduce the contact area with the adhesive layer.

In order to form the surface irregularities as described above, a polypropylene resin such as a polyethylene resin or a polymethylpentene resin may be mixed with a polypropylene resin as a resin composition used for the adhesive layer. It is valid. By doing so, a layer whose surface is rough like a mat can be formed.
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.
It is also possible to add an incompatible resin to the propylene-ethylene block copolymer.

As the resin incompatible with the polypropylene resin, α-olefin (co) polymers having 4 or more carbon atoms such as low density polyethylene and 4-methylpentene-1 (co) polymer are preferably used. Other examples include linear low density polyethylene, high density polyethylene, copolymers of ethylene and a small amount of α-olefin, copolymers of ethylene and vinyl acetate, polystyrene, polyester resins, polyamide resins, and the like. It is done. In particular, 4-methylpentene-1 (co) polymer not only roughens the surface like a mat, but also improves the peelability by lowering the surface free energy of the film surface.

The peel strength of the pressure-sensitive adhesive surface of the pressure-sensitive adhesive film of the present application with respect to the release surface is preferably in the range of 200 cN / 40 mm or less at 23 ° C. from the viewpoint of the film payout property when the pressure-sensitive adhesive film is in roll form. If the peeling force exceeds 200 cN / 40 mm, problems such as partial elongation or deformation of the film when the adhesive film is made into a roll form are caused. In addition, the lower limit of the peeling force with respect to the release surface of the pressure-sensitive adhesive surface of the pressure-sensitive adhesive film is about 1 cN / 40 mm, more preferably about 3 cN / 40 mm as a practical value. The upper limit is more preferably 150 cN / 40 mm.

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

The thickness of the pressure-sensitive adhesive layer of the present invention is preferably 2 μm or more and less than 20 μm. When the thickness of the pressure-sensitive adhesive layer is less than 2 μm, stable film formation by coextrusion becomes difficult, and when it is 20 μm or more, a film is disadvantageous in terms of cost.
At this time, when increasing the adhesive strength, it is preferable to increase the thickness in consideration of the viscosity. Increasing the thickness of the adhesive layer tends to increase the contact area with the adherend. 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 further preferably 15 μm or more and less than 40 μm. When the thickness of the base material layer is less than 5 μm, there is a problem that the waist feeling is weak, wrinkles etc. are easily formed when pasted to a covering as a protective film, and sufficient adhesive strength cannot be obtained. If it is above, the film is disadvantageous in terms of cost.

The thickness of the release layer of the present invention is preferably 2 μm or more and less than 30 μm. If the thickness of the adhesive film is less than 1 μm, stable film formation by coextrusion becomes difficult, and if it is 30 μm or more, the film is disadvantageous in terms of cost. The thickness of the release layer is preferably 2 μm or more and 20 μm or less, and more preferably 3 μm or more and 15 μm or less.
In addition, it is preferable that the thickness of the self-adhesive surface protective film of this invention is 10 micrometers or more and 150 micrometers or less, More preferably, they are 15 micrometers or more and 120 micrometers or less, More preferably, they are 20 micrometers or more and 100 micrometers or less. If the total thickness of the film is too thin, it may be inferior in handling, and if it is too thick, the rigidity becomes high and handling properties are inferior, and the film may be disadvantageous in terms of cost.
The self-adhesive surface protective film of the present invention is composed of a substrate layer containing the above resin component, an adhesive layer, and a release layer, and the resin constituting each layer is, for example, a single-screw or biaxial extruder. It is obtained by being fed into a feed block type or multi-manifold type T die while being 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 in order to bring each layer into a molten state. For example, it may be adjusted in the range of 200 ° C. to 260 ° C. Also good. The temperature of the T die may be the same as the above temperature.

The pressure-sensitive 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 winding length of the film roll is not particularly limited. However, in view of ease of handling, generally, the width is 1600 mm or less, and the winding length is preferably 5000 m or less when the film thickness is 40 μm. Moreover, as a winding core, a plastic core and metal cores, such as 3 inches, 6 inches, and 8 inches, can usually be used.
Moreover, it is preferable that it is the film roll wound up by the dimension of length 100m or more and width 450mm or more from the suitability of a process.

The pressure-sensitive adhesive film of the present invention protects members such as prism sheets used for optical applications from being scratched when stacked, stored, transported, or transported in the manufacturing process. In addition, it can be used to protect the article from scratches during secondary processing (for example, bending or pressing).

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

(1) Adhesive strength Measured by the following method in accordance with JIS-Z-0237 (2000) Adhesive Tape / Adhesive Sheet Test Method.
As an adherend, acrylic plate (Mitsubishi Rayon Co., Ltd .: Acrylite 3 mm thickness) 50 mm × 150 mm, prism sheet (the lens part is composed of a triangular prism, the height of the triangular prism is 25 μm, the width of the triangular prism is 50 μm) 50 mm × 150 mm As a test piece, a test piece of 150 mm in the winding direction at the time of film production and 25 mm in a direction perpendicular thereto is cut out, and a rubber roll having a mass of 2000 g (roller surface spring hardness 80 Hs, thickness 6 mm rubber layer) The adherend and the test piece were reciprocated once at a speed of 5 mm / second and pressure-bonded using a coating having a width of 45 mm and a diameter (including a rubber layer) of 95 mm. After crimping, the sample that was allowed to stand for 30 minutes in an environment at a temperature of 23 ° C. and a relative humidity of 65% was peeled 180 ° at a rate of 300 mm / min using “Autograph” (AGS-J) manufactured by Shimadzu Corporation. The maximum resistance value was defined as the adhesive strength [cN / 25 mm]. 180 degree peeling means holding the peeling angle between the acrylic plate and the film at the time of measuring the resistance value at the time of peeling at 180 degrees.
At the time of measurement, a polyester sheet having a thickness of 190 μm and a size of 25 mm × 170 mm is prepared as a grip margin for the measurement sample, and the width of the paste margin is 15 mm at the end of the measurement sample obtained by pressure-bonding the adhesive film and the acrylic plate. Attached with cellophane tape as a grip for measurement. A schematic diagram of the measurement sample is shown in FIG. The measurement was performed three times for one sample, and the average value was defined as the adhesive strength of the sample.

(2) Resin MFR
Measurement was performed in accordance with JIS-K7210.

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

(4) Peeling force Acrylic board (Mitsubishi Rayon Co., Ltd .: Acrylite 3 mm thickness) 50 mm x 150 mm is pasted on both sides with a double-sided adhesive tape (Nitto Denko Co., Ltd .: No. 535A), A test piece of 150 mm (winding direction at the time of film production) × 50 mm (direction orthogonal to the winding direction at the time of film production) was attached 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 a direction perpendicular thereto is cut out, and the release surface of the test piece attached to the adhesive surface and the acrylic plate via a double-sided adhesive tape After overlapping, a release surface using a rubber roll having a mass of 2000 g (with a spring hardness of 80 Hs on the roller surface and a width of 45 mm and a diameter (including the rubber layer) of 95 mm covered with a rubber layer having a thickness of 6 mm). The test piece was reciprocated once at a speed of 5 mm / second and pressed.
After crimping, a load of 60 kg is applied to a total area of 4000 mm2 of 100 mm in the winding direction and 40 mm in the direction perpendicular to it, left to stand in an environment of a temperature of 40 ° C. and a relative humidity of 65% for 24 hours, and then cooled to 23 ° C. Was peeled 180 ° at a rate of 300 mm / min using “Autograph” (AGS-J) manufactured by Shimadzu Corporation. At the time of measurement, a polyester sheet having a thickness of 190 μm and a size of 40 mm × 170 mm is prepared as a grip allowance for the measurement sample, and is attached to the end of a test piece of 150 mm × 40 mm with a cellophane tape with a width of 15 mm of paste. It was the time to grab. In the measurement, the average resistance value when peeling from 40 mm to 60 mm out of the 100 mm crimping portion of the test piece was defined as the peel strength [cN / 40 mm] of the test piece. The measurement was carried out three times, and the average value was taken as the final peel force.

(5) Peelability of adhesive film from prism sheet, peel strength Prism sheet (the lens part consists of a triangular prism, the height of the triangular prism is 25 μm, the width of the triangular prism is 50 μm) 25 mm × 150 mm is prepared, and a film is used as a test piece. A test piece of 150 mm in the winding direction at the time of production and 25 mm in a direction perpendicular thereto was cut out, and a rubber roll having a mass of 2000 g (coated with a rubber layer having a roller hardness of 80 Hs on the roller surface and a thickness of 6 mm, a width of 45 mm, a diameter) (Including a rubber layer), the adherend and the test piece were reciprocated once at a speed of 5 mm / second and pressure-bonded. This sample was punched out at 90 ° using an additional flea (manufactured by Yokurita Kogyo Co., Ltd., blade width 42 mm) and a shockless hammer (manufactured by OH Industrial Co., Ltd., OS-20).
With respect to the punched end, the ease of peeling when the prism sheet and the film were peeled by hand was evaluated. Those that can be easily peeled off were evaluated as ◯ (good), those that were particularly easy to peel off were evaluated as ◎ (very good), and those that were difficult to peel off by hand were rated as x (defective).
In addition, a cellophane tape is applied to the punched end to create a grip margin, and the peak value of strength when pulled at a speed of 300 mm / min using “Autograph” (AGS-J) manufactured by Shimadzu Corporation [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) Rollability from roll After a 550 mm wide, 500 m roll was obtained with a slit, it was stored in a roll for 7 days in a light-shielding environment at a temperature of 23 ° C. and a humidity of 75%. Immediately after rewinding the film roll after storage to another plastic core (diameter 9 cm) by 300 m, the film end was gripped by hand and pulled back by 3 m. When the film was rewound, it was visually confirmed whether or not the film had partial elongation, deformation, or stopping mark. The case where there was no partial elongation, deformation or stopping mark was indicated as ◯ (good), and the case where there was a partial extension, deformation or stopping mark was indicated as x (defective).

[Example 1]
(Creation of base material layer)
Homo polypropylene resin (Sumitomo Chemical Co., Ltd .: FLX80E4, 230 ° C. MFR: 7.5 g
/ 10 min) 100% by weight was melt extruded at 240 ° C. with a 90 mmφ single screw extruder to form a base material layer.
(Creation of adhesive layer)
Hydrogenated block copolymer of styrene polymer block and butadiene polymer block (Asahi Kasei Chemicals: Tuftec H1221, styrene component ratio 12% by weight, 230 ° C. MFR: 4.5 g / 10 min) 30% by weight and styrene Hydrogenated product of random copolymer of butadiene and butadiene (manufactured by Asahi Kasei Chemicals: SOE L606, styrene component ratio 46% by weight, MFR: 2.9 g / 10 min) and petroleum resin (manufactured by Arakawa Chemical: 15% by weight of Alcon P125) was melt extruded at 210 ° C. with a 40 mmφ single-screw extruder to form an adhesive layer.
(Creation of release layer)
90% by weight of propylene-ethylene block copolymer (manufactured by Nippon Polypropylene: BC3HF) and 10% by weight of low density polyethylene resin (manufactured by Ube Industries: R300) were melt extruded at 230 ° C. with a 65 mmφ single screw extruder to form a release layer. .
(Create film)
Lamination extrusion is performed in a 245 ° C three-layer T die (feed block type, lip width 850 mm, lip gap 1 mm) with the base material layer, adhesive layer, and release layer melted in each extruder. It was. The extruded film is drawn onto a casting roll at a temperature of 30 ° C. at a rate of 20 m / min, cooled and solidified, and the substrate layer thickness is 30 μm, the adhesive layer thickness is 5 μm, the release layer thickness is 5 μm, the film width is 600 mm, and the film length. A three-kind three-layer unstretched film having a length of 1100 m was obtained. Furthermore, this film was slit at a speed of 50 m / min while applying a contact pressure of 50 N to the film width by a rubber roll with a take-up tension of 40 N, whereby an unstretched film having a film width of 550 mm and a film length of 500 m was obtained. Obtained.

[Example 2]
The base material layer and the release layer were the same as in Example 1, but the adhesive layer was changed to the following content, and a three-kind three-layer unstretched film was obtained by the same production method as in Example 1.
(Creation of adhesive layer)
Hydrogenated block copolymer of styrene polymer block and butadiene polymer block (Asahi Kasei Chemicals: Tuftec H1221, styrene component ratio 12 wt%, 230 ° C. MFR: 4.5 g / 10 min) 10 wt% and styrene Hydrogenated product of random copolymer of butadiene and butadiene (manufactured by Asahi Kasei Chemicals: SOE L606, styrene component ratio 46% by weight, MFR: 2.9 g / 10 min) and petroleum resin (manufactured by Arakawa Chemical: 10% by weight of Alcon P125) was melt extruded at 210 ° C. with 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, but the adhesive layer was changed to the following content, and a three-kind three-layer unstretched film was obtained by the same production method as in Example 1.
(Creation of adhesive layer)
Hydrogenated block copolymer of styrene polymer block and butadiene polymer block (Asahi Kasei Chemicals: Tuftec H1221, styrene component ratio 12% by weight, 230 ° C. MFR: 4.5 g / 10 min) 5% by weight and styrene Hydrogenated product of random copolymer of butadiene and butadiene (manufactured by Asahi Kasei Chemicals: SOE L606, styrene component ratio 46% by weight, MFR: 2.9 g / 10 min) and petroleum resin (manufactured by Arakawa Chemical: 10% by weight of Alcon P125) and 5% by weight of ethylene-α-olefin copolymer (Sumitomo Chemical Co., Ltd .: CX3007, 190 ° C. MFR: 3.7 g / 10 min) were melt-extruded at 210 ° C. with a 40 mmφ single screw extruder and adhered. Layered.

[Example 4]
The base material layer was changed to Example 1 while the adhesive layer and the release layer were changed to the following contents, the base material layer thickness was changed to 25 μm, the adhesive layer thickness was set to 10 μm, and the release layer thickness was changed to 5 μm. Three types and three layers of unstretched films were obtained by the same production method.
(Creation of adhesive layer)
Hydrogenated block copolymer of styrene polymer block and butadiene polymer block (Asahi Kasei Chemicals: Tuftec H1221, styrene component ratio 12% by weight, 230 ° C. MFR: 4.5 g / 10 min) 50% by weight and styrene Hydrogenated product of random copolymer of butadiene and butadiene (manufactured by Asahi Kasei Chemicals: SOE L606, styrene component ratio 46% by weight, MFR: 2.9 g / 10 min) and petroleum resin (manufactured by Arakawa Chemical: 15% by weight of Alcon P125) and 20% by weight of ethylene-α-olefin copolymer (Sumitomo Chemical Co., Ltd .: CX3007, 190 ° C. MFR: 3.7 g / 10 min) are melt-extruded at 210 ° C. with a 40 mmφ single-screw extruder and adhered. Layered.
(Creation of release layer)
90% by weight of propylene-ethylene block copolymer (manufactured by Nippon Polypropylene: BC3HF) and 10% by weight of polymethylpentene resin (manufactured by Mitsui Chemicals: RT31) were melt-extruded at 250 ° C. with a 65 mmφ 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, but the adhesive layer was changed to the following content, and a three-kind three-layer unstretched film was obtained by the same production method as in Example 1.
(Creation of adhesive layer)
Hydrogenated block copolymer of styrene polymer block and butadiene polymer block (Asahi Kasei Chemicals: Tuftec H1221, styrene component ratio 12% by weight, 230 ° C. MFR: 4.5 g / 10 min) 40% by weight and styrene Hydrogenated product of random copolymer of butadiene and butadiene (manufactured by Asahi Kasei Chemicals: SOE L606, styrene component ratio 46% by weight, MFR: 2.9 g / 10 min) and petroleum resin (manufactured by Arakawa Chemical: 10% by weight of Alcon P125) and 35% by weight of ethylene-α-olefin copolymer (Sumitomo Chemical Co., Ltd .: CX3007, 190 ° C. MFR: 3.7 g / 10 min) were melt-extruded at 210 ° C. using a 40 mmφ single screw extruder and adhered. Layered.

[Comparative Example 2]
The base material layer and the release layer were the same as in Example 1, but the adhesive layer was changed to the following content, and a three-kind three-layer unstretched film was obtained by the same production method as in Example 1.
(Creation of adhesive layer)
Hydrogenated block copolymer of styrene polymer block and butadiene polymer block (Asahi Kasei Chemicals: Tuftec H1221, styrene component ratio 12 wt%, 230 ° C. MFR: 4.5 g / 10 min) 10 wt% and styrene Hydrogenated product of random copolymer of butadiene and butadiene (manufactured by JSR: Dynalon 1320P, styrene component ratio 10 wt%, 230 ° C. MFR: 3.5 g / 10 min) 80 wt% and petroleum resin (Arakawa Chemical: Alcon P125) 10 The adhesive was melt-extruded at 210 ° C. by 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, but the adhesive layer was changed to the following content, and a three-kind three-layer unstretched film was obtained by the same production method as in Example 1.
(Creation of adhesive layer)
Hydrogenated block copolymer of styrene polymer block and butadiene polymer block (Asahi Kasei Chemicals: Tuftec H1221, styrene component ratio 12% by weight, 230 ° C. MFR: 4.5 g / 10 min) 30% by weight and styrene Hydrogenated product of random copolymer of butadiene and butadiene (manufactured by JSR: Dynalon 1320P, styrene component ratio 10 wt%, 230 ° C. MFR: 3.5 g / 10 min) 55 wt% and petroleum resin (Arakawa Chemical: Alcon P125) 15 The adhesive was melt-extruded at 210 ° C. by 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, but the adhesive layer was changed to the following content, and a three-kind three-layer unstretched film was obtained by the same production method as in Example 1.
(Creation of adhesive layer)
Hydrogenated block copolymer of styrene polymer block and butadiene polymer block (Asahi Kasei Chemicals: Tuftec H1221, styrene component ratio 12% by weight, 230 ° C. MFR: 4.5 g / 10 min) 70% by weight and styrene Hydrogenated product of random copolymer of butadiene and butadiene (manufactured by Asahi Kasei Chemicals: SOE L606, styrene component ratio 46% by weight, MFR: 2.9 g / 10 min) and petroleum resin (manufactured by Arakawa Chemical: 10% by weight of Alcon P125) was melt extruded at 210 ° C. with a 40 mmφ single screw extruder to form an adhesive layer.

[Comparative Example 5]
The base material layer and the adhesive layer were the same as in Example 1, but the release layer was changed to the following content, and a three-kind three-layer unstretched film was obtained by the same production method as in Example 4.
(Creation of release layer)
100% by weight of a homopolypropylene resin (manufactured by Sumitomo Chemical Co., Ltd .: FLX80E4, 230 ° C. MFR: 7.5 g / 10 min) was melt-extruded at 240 ° C. with a 65 mmφ single screw extruder to obtain a base material 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 peel strength that has no practical problem when used as a protective film, and the feeding property when the film is fed as a roll is also good. It was.

On the other hand, the film obtained in Comparative Example 1 had a high peel strength, and it could not be said that the adhesive film was easily peeled after being punched with a mold. The films obtained in Comparative Examples 2 and 3 and 4 and 5 had no problem in peel strength, but the peel strength was large, and it was not possible to say that the feedability when the film was fed as a roll was good. Thus, all the films obtained in the comparative examples were inferior in quality and low in practicality.

Claims

The adhesive layer is laminated on one side of the base material layer made of polypropylene resin, and the release layer is laminated on the other side by coextrusion. The adhesive film and the adherend are bonded together, and the peel strength at the end punched with fleas is A self-adhesive surface protective film characterized by being 60 cN / 25 mm or less and having a peeling force of the adhesive surface to a release surface of 200 cN / 40 mm or less.
2. The self-adhesive polypropylene film according to claim 1, wherein the melt flow rate (MFR: 230 ° C., 2.16 Kgf) of the styrene elastomer in the adhesive layer is 0.5 to 8 g / 10 minutes.
3. The self-adhesive polypropylene system according to claim 1, wherein a melt flow rate (MFR: 230 ° C., 2.16 Kgf) of the polypropylene resin in the base material layer is 1.0 to 15 g / 10 minutes. 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.