JP6901665B2 - Laminate - Google Patents

Description

The present invention is excellent in adhesive properties when bonded to various adherends having irregularities on the surface, and is less likely to be peeled off after a lapse of time or after storage at a high temperature, and further, the adherend is less likely to be contaminated. Regarding the body.

Products made of various materials such as synthetic resin, metal, and glass are often handled with a material that protects the surface in order to prevent scratches and stains that occur during the processing process, transportation process, and storage. A typical example thereof is a surface protective film, which generally has an adhesive layer formed on a supporting base material made of a thermoplastic resin or paper, and the adhesive layer surface is attached to an adherend. The surface is protected by coating with a supporting base material.

Particularly in recent years, liquid crystal displays and touch panel devices have become widespread, and these are composed of a large number of members such as optical sheets and optical films made of synthetic resins. Since it is necessary to reduce defects such as optical distortion as much as possible in such an optical member, a surface protective film is often used in order to prevent scratches and stains that may cause the defects.

The characteristics of the surface protective film are that it does not easily peel off from the adherend when it is subjected to environmental changes such as temperature and humidity or a small amount of stress, and when it peels off from the adherend, an adhesive and an adhesive are applied to the adherend. It is required that no components remain.

Among the above optical members, when a surface protective film is used for an adherend having irregularities on the surface such as a diffusion plate or a prism sheet, the contact area between the surface protective film and the adherend is small, so they are bonded together. It may peel off immediately after, during processing, or after storage. To solve such a problem, a method of increasing the adhesive strength by using a pressure-imparting agent on the pressure-sensitive adhesive layer of the surface protective film is known (for example, Patent Documents 1 and 2).

However, if the adhesive layer contains a large amount of the adhesive, the adhesive may bleed out to the surface of the adhesive layer during storage over time or at a high temperature to contaminate the adherend, or the adhesive strength may increase to adhere. In some cases, it became difficult to peel off from the body.

Japanese Unexamined Patent Publication No. 2011-190370 Japanese Unexamined Patent Publication No. 2013-119603

An object of the present invention is to solve the above-mentioned problems. That is, it is an object of realizing an appropriate adhesive force for protecting various adherends having irregularities on the surface, and suppressing peeling and contamination of the adherend after aging or storage at high temperature.

The above-mentioned problem is a laminate having an adhesive layer on at least one surface of the base material, and the nanoindentation hardness and residual displacement on the adhesive layer side obtained by the nanoindentation test at a temperature of 32 ° C. are the following conditions. This can be achieved by a laminate characterized by satisfying all 1 to 3.

_{Condition 1 Nano indentation hardness H 1} when tested with a maximum load of 0.05 mN is 120 MPa or more and 200 MPa or less Condition 2 Nano indentation hardness H ₂ when tested with a maximum load of 2 mN is 10 MPa or more and 40 MPa or less.

Condition 3 residual displacement _{d p2} when tested at maximum load 2mN is 1.0μm or 3.0μm below.

According to the present invention, in view of the above-mentioned problems, it has appropriate adhesive properties even for various adherends having irregularities on the surface, and it is difficult for peeling to occur after aging or storage at a high temperature, and further. It is possible to provide a laminated body in which contamination of the adherend is less likely to occur.

The laminate of the present invention is a laminate having an adhesive layer on at least one surface of the base material, and the nanoindentation hardness and residual displacement on the adhesive layer side obtained by the nanoindentation test at a temperature of 32 ° C. are as follows. It is a laminated body characterized by satisfying all of the above conditions 1 to 3.

_{Condition 1 Nano indentation hardness H 1} when tested with a maximum load of 0.05 mN is 120 MPa or more and 200 MPa or less Condition 2 Nano indentation hardness H ₂ when tested with a maximum load of 2 mN is 10 MPa or more and 40 MPa or less Condition 3 With a maximum load of 2 mN The residual displacement _dp2 in the test is 1.0 μm or more and 3.0 μm or less.

Here, the adhesive layer refers to a layered layer having an adhesiveness and a finite thickness. Further, the nanoindentation hardness and the residual displacement on the adhesive layer side of the above-mentioned laminated body can be calculated by the method described in Examples described later.

In the laminate of the present invention, when the nanoindentation hardness H ₁ (hereinafter, may be simply referred to as H ₁ ) when tested at a maximum load of 0.05 mN is less than 120 MPa, the adhesive layer is soft and therefore has an adhesive force. May become too large, or the internal stress and external force during storage cannot be suppressed and the product may float over time. On the other hand, when H ₁ is larger than 200 MPa, the adhesive layer is so hard that it does not follow the surface shape of the adherend and may cause problems such as not sticking. H ₁ is more preferably 130 MPa or more and 180 MPa or less, and further preferably 140 MPa or more and 160 MPa or less.

_{Further, when the nanoindentation hardness H 2} (hereinafter, may be simply referred to as H ₂ ) when tested with a maximum load of 2 mN is less than 10 MPa, the follow-up to the uneven portion of the adherend becomes too large. The adhesive strength may become excessive, or the adhesive layer may peel off over time due to the large residual strain of the adhesive layer immediately after sticking. Further, when H ₂ is larger than 40 MPa, the adhesive layer is hard and therefore does not follow the surface shape of the adherend, which may cause a problem such as not sticking. H ₂ is more preferably 15 MPa or more and 35 MPa or less, and further preferably 20 MPa or more and 30 MPa or less.

Examples of the method for controlling the nanoindentation hardnesses H ₁ and H ₂ include a method for controlling the viscoelasticity of the pressure-sensitive adhesive layer, the hardness of the base material, the thickness of the pressure-sensitive adhesive layer and the base material, and the stacking ratio. For example, the higher the storage elastic modulus of the adhesive layer, the higher the nanoindentation hardness. Further, since the adhesive layer is generally softer than the base material, the thinner the pressure-sensitive adhesive layer is, the more easily it is affected by the base material, and the higher the nanoindentation hardness is.

In the laminate of the present invention, when the residual displacement d _p2 when tested at maximum load 2mN is 1.0μm less than sufficient follow-up to the unevenness of the adherend upon bonding the laminate to an adherend It may float over time. On the other hand, if the residual displacement d _p2 is larger than 3.0 μm, the adherend may follow the uneven portion too much and the adhesive force may become excessive. The residual displacement d _p2 is more preferably 1.0 μm or more and 2.0 μm or less.

_Examples of the method for controlling the residual displacement dp2 include a method for controlling the viscoelasticity of the adhesive layer, the hardness of the base material, the thickness of the adhesive layer and the base material, and the lamination ratio. For example, when a soft adhesive layer having a low storage elastic modulus is used, the residual displacement d _p2 becomes large. Further, the larger the loss tangent obtained by dividing the loss elastic modulus of the adhesive layer by the storage elastic modulus, that is, the smaller the contribution of the elasticity of the adhesive layer, the larger the residual displacement d _p2 . Further, since the adhesive layer is generally softer than the base material, the larger the thickness of the adhesive layer, the larger the amount of indentation in the nanoindentation test, and the larger the residual displacement _dp2 .

The laminate of the invention, the maximum displacement d _max2 and residual displacement d _p2 when tested at maximum load 2mN in the nanoindentation test it is preferable to satisfy the following formula (1).
0.30 ≦ (d _p2 / d _max2 ) ≦ 0.60 ・ ・ ・ (1).

When d _p2 / d _max2 is larger than 0.60, it may be easily peeled off with time after the laminated body is attached to the adherend. When d _p2 / d _max2 is smaller than 0.30, d _p2 becomes too small and sufficient adhesive properties may not be exhibited. d _p2 / d _max2 is more preferably 0.40 or more and 0.60 or less, and further preferably 0.50 or more and 0.60 or less. _Examples of the method for controlling d _p2 / d max2 include a method for controlling the viscoelasticity of the adhesive layer, the hardness of the base material, the thickness of the adhesive layer and the base material, and the stacking ratio.

The base material constituting the laminate of the present invention is not particularly limited, but for example, polyolefin or polyester can be used. Among them, it is preferable to use polyolefin as a main component from the viewpoint of productivity and processability. Here, the term "polyolefin as a main component" means that the proportion of polyolefin is 50% by mass or more, more preferably 70% by mass or more, when the entire base material is 100% by mass.

Examples of the polyolefin include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, low-crystalline or amorphous ethylene / α-olefin copolymer, isotactic polypropylene, and syndiotac. Tick polypropylene, propylene / ethylene copolymer (random copolymer and / or block copolymer), propylene / α-olefin copolymer, propylene / ethylene / α-olefin copolymer, ethylene / ethyl (meth) acrylate Examples thereof include copolymers, ethylene / methyl (meth) acrylate copolymers, ethylene / n-butyl (meth) acrylate copolymers, and ethylene / vinyl acetate copolymers. These may be used alone or in combination. The α-olefin is not particularly limited as long as it can be copolymerized with propylene or ethylene, and for example, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-pentene, etc. 1-Heptene can be mentioned. Among the above-mentioned polyolefins, polypropylene, propylene / ethylene copolymer (random copolymer and / or block copolymer), propylene / ethylene / α-olefin copolymer, and propylene / α-olefin, which can obtain high rigidity, A propylene-based resin such as a copolymer is more preferable.

When a propylene-based resin is contained as the composition constituting the base material in the present invention, it is preferable to further contain a crystal nucleating agent. By containing the crystal nucleating agent, the crystallization temperature of the laminate of the present invention can be improved, and the rigidity of the laminate and the heat resistance can be further enhanced.

Examples of the crystal nucleating agent include sorbitol-based compounds, nonitol-based compounds, phosphate ester-based compounds, rosin-based compounds, carboxylic acid metal salt-based compounds, amide-based compounds, aromatic sulfonic acid-based compounds, and quinacridone-based compounds. However, among these, phosphate ester compounds are particularly preferable. Examples of the phosphoric acid ester compound include aluminum-bis (4,4', 6,6'-tetra-tert-butyl-2,2'-methylenediphenyl-phosphate) -hydroxydo and phosphoric acid-2,2'. -Methylenebis (4,6-di-tert-butylphenyl) lithium salt-based compound can be mentioned, but the present invention is not limited to this. Examples of commercially available phosphoric acid ester-based nucleating agents include "ADEKA STAB NA-11", "ADEKA STAB NA-21", "ADEKA STAB NA-27", and "ADEKA STAB NA-71" manufactured by ADEKA.

The content of the crystal nucleating agent in the substrate in the present invention is not particularly limited, but is preferably 0.05 to 1% by mass, preferably 0.1 to 0.5% by mass, assuming that the entire substrate is 100% by mass. Preferably, 0.15 to 0.4% by mass is particularly preferable. If the content of the crystal nucleating agent is less than 0.05% by mass, the crystallization temperature of the laminate of the present invention cannot be sufficiently improved, and the rigidity and heat resistance of the laminate may be insufficient. .. On the other hand, if the content of the crystal nucleating agent is more than 1% by mass, the dispersibility in the base material becomes insufficient, and the transparency of the laminated body may be impaired or defects such as foreign substances may occur.

The laminate of the present invention preferably has a crystallization temperature Tc of 118 ° C. or higher. If the crystallization temperature Tc is less than 118 ° C., the rigidity of the laminated body becomes insufficient, and problems such as wrinkles may occur in the manufacturing process and the processing process of the laminated body. Further, when the laminated body is bonded to the adherend and then cut to a predetermined size, if the rigidity of the laminated body is insufficient, the cutability is poor and an excessive force is applied around the cut portion to form the laminated body. It may be pressed against the adherend, or the laminated body may be deformed to cover the end face of the cut portion, making it difficult to peel off. The crystallization temperature Tc is more preferably 120 ° C. or higher, and even more preferably 124 ° C. or higher. Further, when a propylene resin is used as the composition constituting the base material, the practical upper limit of the crystallization temperature Tc is about 135 ° C. Examples of the method of controlling the crystallization temperature Tc include a method of using a highly crystalline resin as the resin constituting the base material and a method of using a crystal nucleating agent as described above.

The tensile elastic modulus of the laminate of the present invention at 23 ° C. is preferably 600 to 2,000 MPa. The tensile elastic modulus referred to here is the elastic modulus when the laminated body is pulled in the MD direction under predetermined conditions, and can be calculated by the method described in Examples described later. The tensile elastic modulus is more preferably 800 to 1,500 MPa.

If the tensile elastic modulus is less than 600 MPa, the rigidity of the laminate becomes low and it becomes difficult to handle in the manufacturing process or processing process, or after the laminate is attached to the adherend, it is cut to a predetermined size. At that time, the cutability may be poor, and an excessive force may be applied around the cut portion to press the laminated body against the adherend, or the laminated body may be deformed to cover the end face of the cut portion, making it difficult to peel off. When the tensile elastic modulus exceeds 2,000 MPa, the rigidity of the film becomes too high, and in particular, the followability to an adherend having irregularities on the surface may be insufficient, and the stickability may decrease.

As a method of controlling the tensile elastic modulus of the laminate, for example, a method of appropriately selecting the type of the composition constituting the substrate such as the propylene resin or the crystal nucleating agent described above, or a heat treatment or stretching treatment of the laminate or the substrate. A method of appropriately adjusting the stacking ratio of each layer constituting the laminated body, and the like, and a method of adding a crystal nucleating agent to the base material are preferable.

The melt flow rate of the polyolefin mainly used as the base material in the present invention (measured under the conditions of MFR, 230 ° C. and 2.16 kg) is preferably in the range of 2 to 30 g / min, and particularly preferably in the range of 5 to 30 g / min. If the MFR is less than 2 g / min, the melt viscosity is too high and the productivity may decrease. Further, if the MFR is larger than 30 g / min, the base material becomes brittle and may be difficult to handle during the production or use of the laminate.

The base material in the present invention may be composed of two or more layers. For example, an adhesive layer for good adhesion between the pressure-sensitive adhesive layer and the base material may be provided, or a rough surface for controlling the surface roughness of the pressure-sensitive adhesive layer surface. A layer may be provided.

Further, in the composition constituting the base material in the present invention, various additives such as lubricants, antioxidants, weather resistant agents, antistatic agents, pigments and the like are added as long as the characteristics of the laminate of the present invention are not impaired. It may be added as appropriate.

The thickness of the base material can be appropriately adjusted in order to obtain the required characteristics of the laminate and the effects of the present invention, but is preferably 5 to 200 μm, more preferably 10 to 100 μm, and even more preferably 20 to 80 μm. If it is thinner than 5 μm, the strength will be insufficient, and it may be difficult to transport it in the manufacturing process, or it may be torn during processing or use. If it is thicker than 200 μm, the transparency of the film may be insufficient or the productivity may be lowered.

The composition for forming the pressure-sensitive adhesive layer in the present invention is not particularly limited as long as the effects of the present invention are not impaired, and for example, a styrene-based elastomer can be used. Specifically, styrene-conjugated diene copolymers such as styrene-butadiene copolymer (SBR), styrene-isoprene-styrene copolymer (SIS), styrene-butadiene-styrene copolymer (SBS), and theirs. Hydrohydrates (eg, hydrogenated styrene-butadiene copolymer (HSBR), styrene, ethylene, butylene, styrene copolymer (SEBS)) and styrene-isobutylene copolymers (eg, styrene, isobutylene, styrene triblock) Copolymers (SIBS), styrene-isobutyrene block copolymers (SIB), or mixtures thereof) can be used. Among the above, hydrogenated styrene / butadiene copolymer (HSBR), styrene / ethylene / butylene / styrene copolymer (SEBS), and styrene / isobutylene copolymer are preferably used. Only one type of the above-mentioned styrene-based elastomer may be used, or two or more types may be used in combination. Further, if necessary, a material other than the styrene-based elastomer may be used in combination.

The weight average molecular weight of the styrene-based elastomer is preferably in the range of 50,000 to 400,000, more preferably in the range of 50,000 to 200,000. If the weight average molecular weight is less than 50,000, the cohesive force of the adhesive layer may decrease and adhesive residue may occur when peeled from the adherend, and if it exceeds 400,000, the viscosity increases and the productivity decreases. There is.

The styrene content in the styrene-based elastomer is preferably in the range of 5 to 50% by mass, more preferably in the range of 8 to 40% by mass. If the styrene content is less than 5% by mass, the cohesive force of the adhesive layer is reduced, and adhesive residue may be generated when the adhesive layer is peeled off from the adherend. It will be lowered, and the adhesiveness may be insufficient especially for the adherend having unevenness.

In addition to the above-mentioned styrene-based elastomer, amorphous or crystalline polyolefin may be added to the adhesive layer in the present invention. For example, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, low crystalline or amorphous ethylene / α-olefin copolymer, crystalline polypropylene, low crystalline polypropylene, amorphous Polypropylene, propylene / ethylene copolymer (random copolymer and / or block copolymer), propylene / α-olefin copolymer, propylene / ethylene / α-olefin copolymer, polybutene, 4-methyl-1- Penten / α-olefin copolymer, ethylene / ethyl (meth) acrylate copolymer, ethylene / methyl (meth) acrylate copolymer, ethylene / n-butyl (meth) acrylate copolymer, ethylene / vinyl acetate copolymer Coalescence is mentioned, and these may be used alone or in combination. The α-olefin is not particularly limited as long as it can be copolymerized with ethylene, propylene, 4-methyl-1-pentene, and for example, ethylene, propylene, 1-butene, 1-hexene, 4-methyl-. Examples thereof include 1-pentene, 1-octene, 1-pentene and 1-hexene.

Among the above-mentioned polyolefins, low density polyethylene, linear low density polyethylene, ethylene / α-olefin copolymer, polypropylene, propylene / α-olefin copolymer, polybutene, low crystalline polypropylene, amorphous polypropylene, A 4-methyl-1-pentene / α-olefin copolymer is preferably used.

When polyolefin is used for the adhesive layer, the content of the polyolefin is 100% by mass of the entire adhesive layer from the viewpoint of controlling the viscoelasticity of the adhesive layer to adjust the adhesive force and obtaining good film forming property. , 50% by mass or less is preferable, 40% by mass or less is more preferable, and 30% by mass or less is further preferable.

Further, from the viewpoint of controlling the nanoindentation hardnesses H ₁ and H ₂ , residual displacement d _p2 , d _p2 / d _max2 within a preferable range, low crystalline polypropylene, amorphous polypropylene, low crystalline polypropylene, and amorphous Highly flexible resins such as polypropylene, 4-methyl-1-pentene / α-olefin copolymer are preferable, and the amount of these additions is preferably 50% by mass or less when the entire pressure-sensitive adhesive layer is 100% by mass. 40% by mass or less is more preferable, and 30% by mass or less is further preferable.

In addition to the above, the adhesive layer in the present invention may be appropriately added with other components such as wax, tackifier, lubricant, and other additives as long as the object of the present invention is not impaired.

As the above-mentioned wax, for example, paraffin wax, olefin wax and modified wax thereof can be used. For example, in the case of olefin wax, polyethylene wax, polypropylene wax, polybutene wax and modified waxes thereof can be used. The wax used in the present invention preferably has a melting point of 70 to 170 ° C, more preferably 90 to 160 ° C, and even more preferably 110 to 160 ° C. If the melting point is less than 70 ° C, stickiness may occur, and if it is higher than 170 ° C, the moldability may decrease, which may make handling difficult. The wax content is preferably 10% by mass or less when the entire pressure-sensitive adhesive layer is 100% by mass. If it is more than 10% by mass, the adhesiveness may decrease.

Examples of the tackifier include petroleum resins such as aliphatic copolymers, aromatic copolymers, aliphatic / aromatic copolymers and alicyclic copolymers, terpene resins, and terpenes. A phenol-based resin, a rosin-based resin, an alkylphenol-based resin, a xylene-based resin, or a copolymer thereof can be used. The content of the tackifier is preferably 10% by mass or less, more preferably 5% by mass or less, assuming that the entire pressure-sensitive adhesive layer is 100% by mass. If the content of the tackifier is more than 10% by mass, when the pressure-sensitive adhesive layer is molded by the melt extrusion method, a part of the tackifier may sublimate to contaminate the mouthpiece and further adhere to the product. is there. In addition, after the laminate of the present invention is attached to the adherend, adhesive residue may occur when the laminate is peeled off from the laminate to contaminate the adherend.

The lubricant includes a fatty acid, a fatty acid amide, or a fatty acid metal salt having at least one alkyl group or alkenyl group having 4 to 60 carbon atoms, particularly a linear alkyl group or linear alkenyl group having 4 to 30 carbon atoms in the molecule. Can be used, and examples thereof include fatty acids such as lauric acid, palmitic acid, stearic acid, behenic acid, oleic acid, and erucic acid, and metal salts and amide compounds of these fatty acids. The content of the lubricant is preferably 5% by mass or less, more preferably 3% by mass or less, assuming that the entire pressure-sensitive adhesive layer is 100% by mass. If the content of the lubricant is more than 5% by mass, it may bleed out to the surface and contaminate the adherend, the adhesiveness may decrease and the stickiness may decrease, or peeling may occur over time. is there.

In addition, examples of the above-mentioned other additives include antioxidants, weather resistant agents, antistatic agents and the like. These additives may be used alone or in combination, but the total content is preferably 3% by mass or less, more preferably 2% by mass or less, when the entire pressure-sensitive adhesive layer is 100% by mass. If the total content of these additives is more than 3% by mass, it may bleed out from the adhesive layer, causing defects in the product or contaminating the adherend.

The thickness of the adhesive layer in the present invention can be appropriately adjusted according to the material, thickness, surface shape and required level of the adherend, but is preferably 1 to 20 μm, more preferably 2 to 10 μm, and particularly preferably 2 to 8 μm. If the thickness of the adhesive layer is smaller than 1 μm, the nanoindentation hardness becomes too high to sufficiently follow the surface irregularities of the adherend and the adhesive force is not developed, or if it is larger than 20 μm, the adhesive force becomes excessive. Or productivity may decrease.

The laminate of the present invention is a laminate having at least a base material and an adhesive layer, but a release layer may be provided on the surface of the base material opposite to the adhesive layer. The material, thickness, and surface shape constituting the release layer may be selected and adjusted from the viewpoints of the adhesive strength of the adhesive layer and the processing suitability at the time of manufacturing or using the laminate, and techniques known in the art are used. be able to. Preferably, from the viewpoint of satisfactorily controlling the releasability, a propylene-based resin containing 0.5% by mass to 10% by mass of a fluorine-containing compound having a polyfluorohydrocarbon group and a polyoxyethylene group at the same time is mainly composed. Is preferable.

The propylene-based resin may be the same as or different from the resin constituting the base material, but contains at least 20% by mass of a copolymer of propylene and ethylene and / or α-olefin. It is preferable to contain the above amount in order to roughen the surface roughness of the release layer, which will be described later, to 3.0 μm or more in Rz. When the propylene-based resin is a copolymer of ethylene and / or α-olefin, the higher the content of comomoma, the lower the melting point of the copolymer, the ease of coextrusion, and the ability to extrude at low temperature. Therefore, the copolymer content is more preferably in the range of 3 to 7% by mass. If it is desired to add heat resistance to the release layer, it is possible to reduce the content of comoma and appropriately select it so as to obtain desired heat resistance.

The MFR of the propylene-based resin measured under the conditions of 230 ° C. and 2.16 kg is preferably in the range of 3 to 40 g / 10 minutes. In particular, those having an MFR in the range of 10 to 40 g / 10 minutes are more preferable because they can be extruded at a low temperature and the release layer can be easily roughened by combining with low density polyethylene.

In order to roughen the release layer, it is preferable to contain at least 4% by mass of high-pressure low-density polyethylene having poor compatibility with the propylene-based resin.

Further, the release layer is preferably composed of a propylene-based resin containing 0.5% by mass to 10% by mass of a fluorine-containing compound containing a polyfluorohydrocarbon group and a polyoxyethylene group at the same time. Examples of the hydrocarbon group- and polyoxyethylene group-containing fluorine compound include (meth) acrylic acid esters having a perfluoroalkyl group having 1 to 18 carbon atoms as the monomer (a), which will be described later. It can be obtained by copolymerizing with (meth) acrylic acid ester having a polyoxyethylene group of (b) and (c).

The perfluoroalkyl group of the monomer (a) preferably has 1 to 18 carbon atoms, and more preferably 1 to 6 carbon atoms. The perfluoroalkyl group may be linear or branched. These may be used alone or in combination of two or more.

The (meth) acrylic acid ester having a perfluoroalkyl group is commercially available from Kyoeisha Chemical Co., Ltd., but it can also be synthesized by a known method using a fluorine-containing compound as a raw material.

The monomer (b) containing a polyoxyethylene group _{preferably has a structure in which 1 to 30 oxyethylene units (-CH 2-} CH _2- O-) are linked, and in particular, the units are 1 to 20. Is more preferable. The oxypropylene unit (-CH _2- CH (CH ₃ ) -O-) may be contained in the chain. For example, polyethylene glycol monomethacrylate having eight oxyethylene units can be mentioned. The monomer (b) may be used alone or in combination of two or more.

Further, as another monomer (c) containing a polyoxyethylene group, di (meth) having a structure in which oxyethylene units are linked by 1 to 30 and having a double bond at both ends. ) Crylate, a preferred specific example is polyethylene glycol dimethacrylate having 8 chains. As for the monomer (c), only one type can be used alone, or two or more types can be used in combination.

The proportions of the monomers (a), (b), and (c) were 1 to 80% by mass for the monomer (a), 1 to 80% by mass for the monomer (b), and the monomer. (C) is preferably 1 to 50% by mass.

In addition to the above-mentioned three monomers, the fluorine-containing compound having a polyfluorohydrogen group and a polyoxyethylene group contains a monomer copolymerizable with these in a range of less than 50% by mass. It may be polymerized, for example, methylene, vinyl acetate, vinyl chloride, vinyl fluoride, vinyl halide, styrene, methylstyrene, (meth) acrylic acid and its ester, (meth) acrylamide monomer, (meth) allyl. Examples include monomers.

The polymerization method for obtaining a fluorine-containing compound having a polyfluorohydrogen group and a polyoxyethylene group using the above-mentioned monomer may be any of massive polymerization, solution polymerization, suspension polymerization and emulsification polymerization, and heat. In addition to polymerization, photopolymerization and energy ray polymerization can also be adopted.

As the polymerization initiator, existing organic azo compounds, peroxides, persulfates and the like can be used.

The weight average molecular weight of the fluorine-containing compound used in the present invention is preferably 1,000 to 100,000, particularly preferably 5,000 to 20,000. The weight average molecular weight can be adjusted with a polymerization chain transfer agent such as thiol, mercaptan, α-methylstyrene or the like.

The proportion of the fluorine-containing compound in the release layer in the present invention is preferably 0.5% by mass to 10% by mass. If it is less than 0.5% by mass, blocking with the adhesive layer is likely to occur, and it may be difficult to obtain a desired rewinding force. Further, if it is contained in an amount exceeding 10% by mass, the solubility in the resin is low and it is difficult to mix uniformly. Therefore, the propylene-based resin for forming the release layer is affected by the fluorine-containing compound during melt extrusion. It may slip on the extrusion screw and it may be difficult to discharge evenly.

The release layer in the present invention preferably contains 0.1% by mass to 10% by mass of inorganic particles and / or organic particles having an average particle diameter of 1 to 20 μm in addition to the fluorine-containing compound. The average particle size of the inorganic particles and the organic particles is as large as 3 to 15 μm, which is particularly preferable from the viewpoint of slipperiness and blocking property.

Examples of the inorganic particles include silica, calcium carbonate, magnesium carbonate, titanium oxide, clay, talc, magnesium hydroxide, aluminum hydroxide, zeolite and the like, but silica is more preferable.

Examples of the organic particles include polystyrene and polymethylmethacrylate.

Due to the synergistic effect of the fluorine-containing compound, the inorganic particles or the organic particles, and the surface roughness of the release layer described later, blocking is difficult and good unwinding property can be easily obtained.

The surface roughness of the release layer in the present invention is preferably 3 μm or more in terms of ten-point average roughness (Rz). If the Rz is less than 3 μm, wrinkles are likely to occur when the laminated body is wound into a roll in the manufacturing process, which may deteriorate the quality. Examples of the method for controlling Rz to 3 μm or more include a method of mixing and adding a small amount of an ethylene resin having poor compatibility to the propylene resin as described above.

The laminate of the present invention is preferably in the form of a film from the viewpoint of the purpose of use and ease of handling. The thickness of the laminate is preferably 10 to 250 μm, more preferably 10 to 150 μm, and particularly preferably 25 to 100 μm. If the thickness is less than 10 μm, the strain may be insufficient and it may be difficult to handle during manufacturing or use. On the other hand, when the thickness is thicker than 250 μm, it may be difficult to follow the adherend when it is attached to the adherend, or the productivity may decrease.

Next, a method for producing the laminate of the present invention will be described.

The method for producing the laminated body of the present invention is not particularly limited. For example, in the case of a three-layer laminated structure consisting of a base material, an adhesive layer, and a release layer, the resin compositions constituting each are melt-extruded from individual extruders to form a base. Examples include a so-called coextrusion method in which the base material, the adhesive layer, and the release layer are individually melt-extruded and then laminated by a laminating method. From the viewpoint of productivity, coextrusion is used. It is preferably manufactured by the method. As the material constituting each layer, a material mixed with Henschel mixer or the like may be used, or a material obtained by kneading all or a part of the materials of each layer in advance may be used. As the coextrusion method, known methods such as an inflation method and a T-die method are used, but the Fused Deposition Modeling coextrusion method by the T-die method is particularly preferable from the viewpoint of excellent thickness accuracy and surface shape control.

The laminate of the present invention can be used as a surface protective film for manufacturing, processing, transporting, scratch prevention, and dirt adhesion prevention of synthetic resin plates, metal plates, glass plates, etc. It is preferably used for the body. For example, it is used for a diffusion plate and a prism sheet, which are display members made of synthetic resin, and is particularly preferably used as a surface protective film for the prism surface of the prism sheet.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to these Examples. The measurement and evaluation of various physical properties were carried out by the following methods. Unless otherwise stated, the following measurements and evaluations were performed indoors at 25 ° C.

(1) Thickness of Laminated Body Using the microtome method, an ultrathin section having a cross section in the die width direction of the laminated body and the thickness direction of the laminated body was prepared, and the cross section was coated with platinum to prepare an observation sample. Next, using a field emission differential electron microscope (S-4800) manufactured by Hitachi, Ltd., the cross section of the laminate was observed at an acceleration voltage of 1.0 kV, and the thickness of the adhesive layer and the total thickness of the laminate were observed from any part of the observation image. The thickness was measured. The observation magnification was 10,000 times for the adhesive layer and 1,000 times for the laminated body. Further, the same measurement was performed a total of 5 times, and the average value was used as the thickness of the adhesive layer and the total thickness of the laminated body.

(2) Nano-indentation hardness, maximum displacement, and residual displacement on the adhesive layer side of the laminate Using the Nano Indentation Tester ENT-2100 manufactured by Elionix, using a Berkovich indenter (tip triangular pyramid) under the following conditions, From the adhesive layer side of the laminate, a push-in test by a load-unload test was performed 5 times for each type of laminate under each condition (maximum load 0.05 mN condition and maximum load 2 mN condition). The nanoindentation hardness obtained by measuring under the condition of a maximum load of 0.05 mN was defined as H ₁ , and the nanoindentation hardness obtained by measuring under the condition of a maximum load of 2 mN _{was defined as H 2} . The maximum displacement obtained by the measurement under the conditions of maximum load 2 mN d _max2, the residual displacement of a load 0mN and d _p2, respectively, using the mean values obtained in five measurements.
Temperature: 32 ° C
Maximum load: 0.05mN or 2mN
Load speed / unloading speed: 0.005 mN / s (when the maximum load is 0.05 mN) or 0.2 mN / s (when the maximum load is 2 mN)
Load-Load at the start of the unloading test: 0 mN
Holding time at maximum load: 1 second Surface detection method: Tilt method Surface detection threshold coefficient: 2.0
Spring correction: None.

(3) Initial adhesive strength The laminate is cut to a width of 40 mm, and a crimping roller (rubber hardness A80, roller mass 4 kg) is reciprocated three times in the direction perpendicular to the width direction (prism ridge line direction) on a prism sheet having a width of 25 mm. After bonding, the laminated body protruding from the prism sheet was removed. The prism sheet used had a length between the prism ridges of 50 μm and an angle of the tip of the ridges of 90 degrees. The obtained sample was stored in a room at 25 ° C. for 24 hours, and then the adhesive strength was measured and evaluated in the following three stages. In the present invention, from the viewpoint of stickability and peelability, A, B, and C are preferable in this order, and those obtained with an evaluation result of A or B are regarded as acceptable. The adhesive strength was measured using a tensile tester (Orientec Co., Ltd. "Tensilon" universal tester) at a tensile speed of 300 mm / min and a peeling angle of 180 °.
A: Adhesive strength is 2 g / 25 mm or more and less than 5 g / 25 mm B: Adhesive strength is 5 g / 25 mm or more and less than 10 g / 25 mm C: Adhesive strength is less than 2 g / 25 mm or 10 g / 25 mm or more.

(4) Appearance A 40 mm wide laminate and a 40 mm wide prism sheet are bonded together by reciprocating a crimping roller (rubber hardness A80, roller mass 4 kg) three times in the direction perpendicular to the width direction, and then stored for 24 hours and stored in Thomson. It was punched to a size of 30 mm in width and 50 mm in length using a die punching machine. The obtained sample was stored in a hot air dryer at 50 ° C. for 3 days, and the appearance after taking out was visually observed and evaluated in the following 3 stages. The prism sheet used was the same as in (3) above.
⊚: The laminate is not peeled off from the prism sheet at all 〇: The laminate is peeled off from the prism sheet very slightly near the end ×: The laminate is peeled off from the prism sheet at a place other than the end ..

(5) Contamination After taking out the sample obtained in (4) above from the hot air dryer and storing it at room temperature of 25 ° C. for 1 hour, the laminate was peeled off and the state of contamination on the prism surface was visually confirmed. Then, it was evaluated in the following three stages.
◎: No contamination under fluorescent light and under green light 〇: No contamination under fluorescent light, but slightly contaminated under green light ×: Contamination is observed under fluorescent light ..

(6) Tensile elastic modulus The tensile elastic modulus of the laminate is based on JIS K 7113 (1995) using a tensile tester (Orientec universal tester Tensilon), and the laminate is placed in a room at a temperature of 23 ° C. Tensile measurement was performed in the MD direction and calculated.

(7) Edge peelability In the same manner as in (4) above, the laminate and the prism sheet were bonded together, and then punched to a size of 30 mm in width and 50 mm in length with a Thomson type punching machine. Then, one end of the short side of the sample was grasped by hand, and the laminate was peeled from the adherend in the longitudinal direction of the sample. The peeling was carried out 5 times for each laminated body, and the peeling property at that time was defined as the edge peeling property and evaluated according to the following criteria.
⊚: Easy peeling was possible 5 times out of 5 times 〇: Easy peeling was possible 4 times out of 5 times, but could not be peeled off at one time other than that △: 3 times out of 5 times was easily peeled off However, other than that, it could not be peeled off at once. ×: It could be easily peeled off twice out of five times, but otherwise it could not be peeled off at once. It was as follows.

Hereinafter, Examples 1, 2, 4 to 6 will be read as Reference Examples 1, 2, 4 to 6, respectively.
(Example 1)
The constituent resins of each layer were prepared as follows.

Adhesive layer: SEBS (JSR "Dynaron (registered trademark)" 8903P; styrene content 35% by mass, MFR 30g / 10 minutes (measured at 230 ° C., 2.16kg)) 75% by mass, 4-methyl-1-pentene 20% by mass of propylene copolymer and 5% by mass of hydrogenated terpenephenol (“YS Polystar (registered trademark)” TH130 manufactured by Yasuhara Chemical Co., Ltd.) were used. The 4-methyl-1-pentene / propylene copolymer has a copolymerization ratio of 73 mol% for 4-methyl-1-pentene, 27 mol% for propylene, and 10 g / 10 minutes for MFR (230 ° C., 2). (Measured at 16.16 kg) was used.

Substrate: Commercially available homopolypropylene (isotactic polypropylene) having an MFR of 5 g / 10 minutes (measured at 230 ° C. and 2.16 kg) was used.

Release layer: 45% by mass of the same homopolypropylene used for the base material, and 24% by mass (ethylene content) of propylene-ethylene random copolymer having an MFR of 35 g / 10 minutes (measured at 230 ° C. and 2.16 kg). 5 wt%), MFR is 2 g / 10 min (190 ° C., a low density polyethylene having a density of 920 kg / ^{m 3} measurements) added to reach 6% by weight 2.16 kg, average particle advance to the homopolypropylene 90% by weight A mixed composition consisting of 4% by mass of silica having a diameter of 11 μm and 6% by mass of a fluorine-containing compound having a polyfluorohydrogen group and a polyoxyethylene group was prepared as a master batch, and 25% by mass was uniformly mixed with a Henschel mixer. ..

Here, the fluorine-containing compound having a polyfluorohydrogen group and a polyoxyethylene group is a perfluoroalkyl acrylate of _{C 6} F _{13 as the monomer (a) (CH 2} = CHCOOC ₂ H ₄ C ₆ F ₁₃ ). 25% by mass, 50% by mass of polyethylene glycol monoacrylate {CH ₂ = CHCOO (CH ₂ CH ₂ O) ₈ H} having 8 oxyethylene repeating units, and the monomer (c). As an oxyethylene repeating unit, 8 polyethylene glycol dimethacrylates {CH ₂ = C (CH ₃ ) COO (CH ₂ CH ₂ O) ₈ COC (CH ₃ ) = CH ₂ } were added to the solvent in a proportion of 25% by mass. Polymerization of fluorotoluene with 2,2'-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator and lauryl mercaptan as a chain transfer agent at 60 ° C. for 5 hours with stirring under a nitrogen stream. After that, the mixture was precipitated and filtered in methanol, and then dried under reduced pressure.

Next, the constituent resin of each layer is put into each extruder of the T-die composite film forming machine having three extruders, and each extruder has an adhesive layer of 5 μm, a base material of 30 μm, and a release layer of 5 μm. Was extruded from the composite T-die at an extrusion temperature of 200 ° C. to form a film.

Then, with respect to the obtained laminate, nanoindentation on the adhesive layer side of the laminate, maximum displacement, residual displacement, initial adhesive strength, appearance and stainability after heat storage, and the laminate by the above method. The crystallization temperature, tensile elastic modulus, and edge peelability were evaluated.

(Example 2)
As the resin constituting the adhesive layer, the amount of SEBS (“Dynaron®” 8903P) was changed to 70% by mass, and the amount of hydrogenated terpenephenol (“YS Polystar®” TH130) was changed to 10% by mass. Other than that, it was the same as in Example 1.

(Example 3)
As the resin constituting the base material, a commercially available propylene / ethylene block copolymer (block) containing 49.8% by mass of the above homopolypropylene and 4 g / 10 minutes of MFR (230 ° C., 2.16 kg) and an ethylene content of 10 mass. Except for the fact that 50% by mass of polypropylene) and 0.2% by mass of "Adecastab (registered trademark)" NA-27 manufactured by Adeca as a crystal nucleating agent were melt-kneaded in advance with a twin-screw extruder and pelletized. Was the same as in Example 1.

(Example 4)
As the resin constituting the adhesive layer, instead of JSR's "Dynaron (registered trademark)" 8903P, JSR's "Dynaron (registered trademark)" 8300P (styrene content 9% by mass, MFR 7g / 10 minutes (230 ° C., 2. It was the same as in Example 1 except that (measured at 16 kg)) was used.

(Example 5)
Except for changing the amount of SEBS (“Dynaron®” 8903P) to 85% by mass and the amount of 4-methyl-1-pentene / propylene copolymer to 15% by mass as the resin constituting the adhesive layer. It was the same as in Example 1.

(Example 6)
The same procedure as in Example 2 was carried out except that 100% by mass of the propylene / ethylene block copolymer was used as the resin constituting the base material.

(Comparative Example 1)
As the resin constituting the adhesive layer, HSBR (JSR "Dynaron (registered trademark)"1321P; styrene content 10% by mass, MFR 10g / 10 minutes (measured at 230 ° C., 2.16kg)) was 30% by mass, SEBS ( Asahi Kasei Chemicals "Tough Tech (registered trademark)"H1052; styrene content 20% by mass, MFR 13g / 10 minutes (measured at 230 ° C., 2.16kg)) 30% by mass, density 921kg / m ³ and MFR 5g / 10 Example 1 except that the amount of linear low-density polyethylene (measured at 190 ° C. and 2.16 kg) was 25% by mass and the amount of hydrogenated terpenephenol (“YS Polystar®” TH130) was 15% by mass. The same was true.

(Comparative Example 2)
As the resin constituting the adhesive layer, HSBR (“Dynaron (registered trademark)” 1321P) was 60% by mass, the linear low-density polyethylene described in Comparative Example 1 was 20% by mass, and hydrogenated terpenephenol (“YS Polystar (” YS Polystar). The same as in Example 1 except that the registered trademark) "TH130) was set to 20% by mass.

(Comparative Example 3)
Example 1 except that HSBR (“Dynaron®” 1321P) was 95% by mass and hydrogenated terpenephenol (“YS Polystar®” TH130) was 5% by mass as the resin constituting the adhesive layer. It was the same as.

(Comparative Example 4)
It was the same as in Comparative Example 2 except that 100% by mass of the above propylene / ethylene block copolymer was used as the resin constituting the base material.

All of Examples 1 to 6 satisfying the requirements of the present invention showed good initial adhesive strength, and were excellent in stickability and peelability to the prism sheet. Furthermore, no peeling or contamination was observed after heating and storage. Further, Example 3 was particularly excellent in edge peelability after punching. On the other hand, in Comparative Examples 1 and 3, peeling from the prism sheet was confirmed after heating and storage. Further, in Comparative Examples 2 and 4, contamination of the prism sheet was confirmed after heating and storage, and the edge peelability was also inferior.

The laminate of the present invention is used not only as a surface protective film for preventing scratches and stains on an adherend having irregularities on the surface, but also as a surface protective film for various products made of various materials such as synthetic resin, metal, and glass. It can be preferably used.

Claims (4)

A laminate having an adhesive layer on at least one surface of the substrate, the substrate contains a crystal nucleating agent, and the nanoindentation hardness and residue on the adhesive layer side obtained by a nanoindentation test at a temperature of 32 ° C. displacement meets 1-3 all of the following conditions, the tensile modulus at 23 ° C. of the laminate is 800～2,000MPa, laminate.
_{Condition 1 Nano indentation hardness H 1} when tested with a maximum load of 0.05 mN is 120 MPa or more and 200 MPa or less Condition 2 Nano indentation hardness H ₂ when tested with a maximum load of 2 mN is 10 MPa or more and 40 MPa or less Condition 3 With a maximum load of 2 mN Residual displacement d _p2 in the test is 1.0 μm or more and 3.0 μm or less In the nanoindentation test, the laminate of the maximum displacement d _max2 and residual displacement d _p2 when tested at maximum load 2mN stated請Motomeko 1 satisfying the following formula (1).
0.30 ≦ (d _p2 / d _max2 ) ≦ 0.60 ・ ・ ・ (1) The laminate according to請Motomeko 1 or 2 wherein the adhesive layer contains a styrene-based elastomer. Laminate according to any one of請Motomeko 1-3 for use as a surface protective film of the prism surface of the prism sheet.