JP5424169B2 - Polyolefin resin multilayer film - Google Patents

Description

  The present invention relates to a polyolefin resin multilayer film. More specifically, it is strong, has excellent blocking resistance, has low curl, low powder and UV resistance, food / beverage, pharmaceutical / medical product, optical film, liquid crystal component, electronic / electrical component, precision component It is a polyolefin resin multilayer film suitable for packaging materials such as the above and solar cell materials.

  Conventionally, polyolefin resin films such as polyethylene and polypropylene have excellent strength, transparency, heat sealability, moisture resistance, chemical resistance, and low temperature impact strength, so that they can be used in food / beverages, pharmaceuticals / medical products, and industries. It is widely used as various packaging materials such as materials and daily life materials. In recent years, the polyethylene film used to store and transport food / beverages, pharmaceuticals / medicine, optical films, liquid crystal components, electronic / electrical parts, precision parts, etc. requires cleanliness in addition to the above physical properties. In addition, it has been demanded to develop clean properties such as low powder properties and low outgassing properties. Furthermore, in outdoor applications such as solar cells, it is originally a polyethylene film that is weak against ultraviolet rays. Its weather resistance, reflectivity, and maintenance of design properties due to coloring, and curling and misalignment do not occur during secondary processing such as lamination. Handling properties such as these are also required.

  As a method of whitening for the purpose of imparting design properties to a polyethylene film, a method of kneading titanium oxide is generally known. However, when high concealability and reflectance are imparted, the addition amount must be increased. Don't be. In this case, FE (fish eye) is generated due to poor dispersion of titanium oxide. Moreover, when it shape | molds by the T-die casting method, dies will become dirty, and problems, such as eyes and a streak, will arise. In addition, there is a problem that a titanium oxide dispersant volatilizes to generate gas.

Moreover, in patent document 1, as a back sheet for solar cells, an ultraviolet blocker or an antioxidant is added to a polyethylene resin having a density of 0.940 (g / cm ³ ) or more and 0.970 (g / cm ³ ) or less. A method using such a film is disclosed. However, since the resin having a density of 0.940 (g / cm ³ ) or higher has a high density, when the present film is molded by the T-die casting method, there is a problem that the film curls due to crystallization. Furthermore, polyethylene having a density of 0.940 (g / cm ³ ) or more and 0.970 (g / cm ³ ) or less is generally classified as high-density polyethylene (hereinafter abbreviated as HDPE). This HDPE has problems such as scraping powder adhering to the metal roll due to scraping with the take-up roll after casting and the roll during the winding process, and the scraping powder may damage the film and contaminate the film forming process. May occur.

  Patent Document 2 discloses a method for producing a laminated film in which the polyethylene film is strong and difficult to curl. However, since this method does not add an antioxidant, thermal degradation of polyethylene during T-die casting is disclosed. Further, there is a problem that the gel surface and the streaks are generated on the film surface due to oxidative deterioration and the productivity is deteriorated.

  Therefore, such as food / beverage, pharmaceutical / medical products, optical film, liquid crystal material, electronic / electrical parts, precision parts, etc. Development of a polyolefin resin multilayer film suitable for packaging materials and solar cell materials is desired.

JP-A-11-261085 JP 2008-73854 A

  An object of the present invention is to solve the above-described problems. That is, the object of the present invention is a food / beverage, a pharmaceutical / medical product, an optical film, a liquid crystal member, an electronic / electrical product, having a firmness, excellent blocking resistance, small curl, low powder and UV resistance. An object of the present invention is to provide a polyolefin resin multilayer film suitable for packaging materials such as parts and precision parts, and materials for solar cells.

The above-described problems are solved by the polyolefin resin multilayer film according to the present invention. That is, a film having a three-layer structure of A layer / B layer / C layer, wherein the A layer and the C layer are a mixture of low density polyethylene and propylene resin with respect to 100 parts by weight of the ethylene-α-olefin copolymer. It consists of a resin composition in which 5 to 20 parts by weight of a resin is mixed. The B layer is mainly composed of an ethylene-α-olefin copolymer whose density is lower than that of the A and C layers, and the density of the A and C layers is 0. .93 is a 0 g / cm ³ or more, the density of the layer B is less than 0.93 0 g / cm ^3, the thickness of the C layer is a polyolefin resin multilayer film is less than 2/3 of the a layer.

  The polyolefin-based resin multilayer film of the present invention is strong, excellent in blocking resistance, small curl, low powder, UV resistance, food / beverage, pharmaceutical / medical product, optical film, liquid crystal member, It can be suitably used for packaging materials such as electronic / electrical parts and precision parts, and solar cell materials.

  The present invention is a film having a three-layer structure of A layer / B layer / C layer, wherein the A layer and the C layer are composed of low density polyethylene and propylene resin with respect to 100 parts by weight of the ethylene-α-olefin copolymer. It consists of a resin composition in which 5 to 20 parts by weight of a mixed resin is mixed. The B layer is mainly composed of an ethylene-α-olefin copolymer having a lower density than the A layer and the C layer, and the thickness of the C layer is that of the A layer. It is a polyolefin resin multilayer film which is 2/3 or less.

  The A layer and the C layer of the present invention are composed of a resin composition in which 5 to 20 parts by weight of a mixed resin of low density polyethylene and a propylene resin is mixed with 100 parts by weight of an ethylene-α-olefin copolymer. The ethylene-α-olefin copolymer used in the A layer and the C layer in the present invention is a linear low density polyethylene (hereinafter abbreviated as LLDPE) obtained by random copolymerization of ethylene and a small amount of α-olefin. May be).

  The α-olefin is not particularly limited, but is an α-olefin having 4 to 10 carbon atoms, preferably 4 to 8 carbon atoms, and specifically includes 1-butene, 1-pentene, 4-methyl. Examples include -1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, and 1-decene. These α-olefins can be used alone or in combination. Particularly, 1-butene, 1-hexene, 1-octene and the like are preferably used from the viewpoint of polymerization productivity.

The density of the ethylene-α-olefin copolymer used in the present invention is preferably 0.930 g / cm ³ or more, more preferably 0.930 to 0.945 g / cm ³ . When the density is higher than 0.945 g / cm ³ , the resin is liable to fall off during rubbing with a metal roll or a rubber roll, which may cause generation of white powder. Moreover, when lower than 0.930 g / cm < ³ >, it becomes difficult to obtain desired slipperiness and handling property.

In the present invention, the α-olefin content in the ethylene-α-olefin copolymer is preferably 0.5 to 10 mol%, more preferably 2.0 to 8.0 mol%. By setting the α-olefin content to 0.5 to 10 mol%, the density of the ethylene-α-olefin copolymer can be set to a range of 0.930 to 0.945 g / cm ³ .

  The melt index (hereinafter abbreviated as MFR) at 190 ° C. of the ethylene-α-olefin copolymer used in the present invention is preferably 1.0 to 10.0 g / 10 min, more preferably 1.5 to 7 0.0 g / 10 min. If the MFR is larger than 10.0 g / 10 minutes, necking down and uneven lamination with other layers are likely to occur during film production. On the other hand, if the MFR is lower than 1.0 / 10 minutes, the handling property at the time of casting and the embrittlement due to the improvement in crystallinity tend to occur.

  The ethylene-α-olefin copolymer used in the present invention can be produced by a synthesis method using a conventional multi-site catalyst or a synthesis method using a single-site catalyst (Kaminsky catalyst, metallocene catalyst). The production method of the ethylene-α-olefin copolymer is preferably a multi-site catalyst from the viewpoint of improving slipperiness and imparting strength.

  In the present invention, it is necessary to mix 5 to 20 parts by weight of a mixed resin of low density polyethylene and propylene resin with respect to 100 parts by weight of the ethylene-α-olefin copolymer. If the mixed resin of low-density polyethylene and propylene resin is less than 5 parts by weight, the Young's modulus will be low and the film will be weak, so the film may stretch during film winding or laminating. In some cases, the slipperiness of the film decreases, wrinkles occur in the film, and process passability deteriorates. On the other hand, if it exceeds 20 parts by weight, the crystallinity of the resin component constituting the A layer and the C layer becomes faster, the adhesion to the casting drum may deteriorate, and the smoothness of the film surface may deteriorate, When laminating another base material on the polyolefin resin multilayer film of the present invention, there are cases where air bubbles are bitten at the interface with the other base material. The blending ratio of the low density polyethylene and the propylene resin to be mixed is preferably 90 to 60 parts by weight of the propylene resin with respect to 10 to 40 parts by weight of the low density polyethylene. In particular, the blending ratio is more preferably 85 to 70 parts by weight with respect to 15 to 30 parts by weight of low-density polyethylene due to the problem of processability.

Examples of the low density polyethylene resin include those obtained by polymerization using a Ziegler-Natta type or a metallocene catalyst. The density of the low density polyethylene resin is preferably 0.900 to 0.929 g / cm ³ . If the density of the low-density polyethylene resin is 0.900 cm ³ or more, desired slipping and handling properties can be obtained, but if the density is higher than 0.929 g / cm ³ , in rubbing with a metal roll or rubber roll, Resin is shaved off and easily falls off, which also causes white powder.

  Examples of the propylene-based resin include homopolypropylene and random or block copolymers of ethylene and propylene, including heat resistance, slipperiness, film handling, scratch resistance, and curl resistance. To homopropylene are most preferred. When a copolymer of ethylene and propylene is used as the propylene resin, the ethylene content is preferably in the range of 1 to 7 mol%. Moreover, when it is desired to impart strength to the film, it is preferable to add a nucleating agent as necessary. Among these, α nucleating agents are preferable, and specific examples include sorbitol-based and cyclopentadiene-based crystal nucleating agents.

  The propylene-based resin preferably has an MFR at 230 ° C. of 3 to 15 g / 10 min, and the low-density polyethylene has an MFR at 190 ° C. of preferably 5 to 30 g / 10 min. By setting the MFR of the propylene-based resin and the low-density polyethylene in the above range, the dispersibility of the mixed resin of the low-density polyethylene and the propylene-based resin in the A layer and the C layer is improved, and the performance of the film of the present invention is improved. . Further, the larger the difference between the MFR at 230 ° C. of the propylene-based resin and the MFR at 190 ° C. of the low-density polyethylene, the better the slipperiness and handling properties are expressed.

  In addition, inorganic compound fine particles, organic compound lubricants, and the like are added to the A layer and the C layer for the purpose of imparting slipperiness as long as the physical properties thereof are not hindered and line contamination due to the removal of the fine particles is not caused. I can. Addition of inorganic compound fine particles and organic compound lubricants to the A layer as much as possible, and addition to the C layer as much as possible does not cause line contamination due to dropping off of the fine particles, improving winding and laminating properties. Therefore, it is preferable.

  Examples of the fine particles of the inorganic compound include talc, silicon oxide, zeolite, and titanium oxide. Examples of the organic compound lubricant include stearamide and calcium stearate. Furthermore, an antioxidant, an ultraviolet absorber, a pigment, an antistatic agent, a nucleating agent, and the like may be appropriately added to the A layer and the C layer. You may add these individually or in combination of 2 or more types.

  The average surface roughness Ra of the C layer in the present invention is preferably 0.10 to 0.30 μm because the film handling function during processing is satisfied.

The A layer and / or the C layer in the present invention, if the density using a HDPE of ^{0.94g / cm 3 ~0.97g / cm 3} , the waist of the film, and although having excellent curl, roll friction during processing HDPE falls off and generates white powder, which may cause problems such as soiling or scratching the film.

In the A layer and / or C layer in the present invention, particles having an average particle diameter of 1 to 5 μm are added to 100 parts by weight of the resin component of the A layer and / or C layer for the purpose of improving the handleability and slipperiness of the film. It is preferable to add 0.1 to 10 parts by weight. As particles to be added to the A layer and / or the C layer, for example, inorganic particles such as wet silica, dry silica, colloidal silica, aluminum silicate, calcium carbonate, styrene, silicone, acrylic acid, methacrylic acid, divinylbenzene, etc. As a constituent component, crosslinked organic particles and the like can be used. Among these, use of aluminum silicate is preferable. An average particle diameter of 1 μm or more is preferable because the slipperiness of the film is improved. On the other hand, if the average particle diameter is larger than 5 μm, the particles fall off from the film and cause contamination and scratches, which is not preferable.
Moreover, when the addition amount of particle | grains is less than 0.1 weight part, the improvement power of slipperiness is weak and is not preferable. On the other hand, when the added amount exceeds 10 parts by weight, it is not preferable because the particles easily fall off from the film and are caused by contamination and scratches.

B layer in this invention consists of a resin component which has an ethylene-alpha-olefin copolymer as a main component, and the density of B layer needs to be lower than A layer and C layer. The ethylene-α-olefin copolymer here is a linear polyethylene obtained by random copolymerization of ethylene and a small amount of α-olefin similar to those in the A layer. When the density of the A layer and the C layer is less than or equal to the B layer, the slipperiness and blocking resistance of the film are inferior.
In the present invention, the α-olefin used in the B layer is not particularly limited, but is an α-olefin having 4 to 10 carbon atoms, preferably 4 to 8 carbon atoms. Examples include butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene and 1-decene. These α-olefins can be used alone or in combination.

  In this invention, 0.5-10 mol% is preferable and, as for the alpha-olefin content in the ethylene-alpha-olefin copolymer used by B layer, More preferably, it is 2.0-8.0 mol%.

  In the present invention, the ethylene-α-olefin copolymer used for the B layer preferably has a melt index (MFR) of 1.0 to 10.0 g / 10 minutes, more preferably 1.5 to 7.0 g / 10. Minutes. If the viscosity is lower than 1.0 g / 10 min, it may cause neck-down during film production and uneven lamination with other layers.

The ethylene-α-olefin copolymer used in the B layer of the present invention preferably has a density of less than 0.930 g / cm ³ , more preferably 0.910 to 0.925 g / cm ³ . is there. When the density is higher than 0.930 g / cm ³ , the film curls due to crystallization, so that the handling property at the time of processing is poor, and problems such as winding deviation occur.

  Moreover, as a manufacturing method of the ethylene-alpha-olefin copolymer used by B layer of this invention, in addition to the synthesis method by the conventional multi-site catalyst, the synthesis method using a single site catalyst (Kaminsky catalyst, metallocene catalyst) Is mentioned.

  Moreover, when mixing 5-30 parts by weight of rutile-type titanium oxide particles coated with an inorganic oxide having an average particle diameter of 0.2-0.5 μm on the B layer with respect to 100 parts by weight of the resin component of the B layer, it was excellent. Since whiteness and light reflectivity are obtained, it is preferable.

  Titanium oxide particles used in the present invention are not particularly limited, but are known as a rutile type, anatase type, brookite type, and the like, and have excellent whiteness, weather resistance and light reflectivity. The rutile type is preferable from the above characteristics.

  Since the titanium oxide used in the present invention may deteriorate the resin by photocatalysis, it is preferably surface-coated for the purpose of stabilizing the photocatalysis, and the composition is not limited, but silicon oxide Inorganic oxides such as alumina, zinc oxide and zinc oxide are preferred. The coating method of the surface coating agent is not particularly limited, and titanium oxide particles obtained by a known method can be used.

  Furthermore, for the purpose of stabilizing the titanium oxide particles, for example, a light stabilizer such as a hindered amine may be added to the resin. However, in this case, it is important to screen so as not to cause secondary aggregation of the titanium oxide particles.

  The average particle diameter of the titanium oxide particles used in the present invention is preferably 0.2 to 0.5 μm, and more preferably 0.25 to 0.35 μm. If the average particle diameter is smaller than 0.2 μm, the activity of the titanium oxide particles is high, which is not preferable because it causes resin deterioration. On the other hand, if the average particle diameter exceeds 0.5 μm, the dispersibility in the resin is deteriorated and it is not preferable because it is caused by clogging of the filter used at the time of film production.

  The amount of titanium oxide used in the present invention is preferably in the range of 5 to 30 parts by weight, more preferably in the range of 10 to 20 parts by weight, based on the film weight. If the mixing amount is less than 5 parts by weight, the whitening and light reflection effects are low, and if it exceeds 30 parts by weight, dispersibility in the resin may deteriorate, which is not preferable.

Moreover, when using it for the solar cell material for the A layer, the B layer, and the C layer in the present invention, a phosphorus-phenol antioxidant, for example, 6 as an antioxidant from the viewpoint of discoloration prevention and strength maintenance. -[3- (3-t-butyl-4-hydroxy-5-methyl) propoxy] -2,4,8,10-tetra-t-butyldibenz [d, f] [1,3,2] -dioxa Addition of phosfepine (Sumitomo Chemical SumilizerGP (registered trademark)) is preferable because thermal stability and weather resistance during extrusion are improved. The addition amount is preferably in the range of 0.05 to 0.35% by weight with respect to the resin composition weight of each layer. If the addition amount is less than 0.05% by weight, the effect is low, and if it exceeds 0.35% by weight, the dispersibility may deteriorate. Antioxidants other than SumilizerGP can also be used.
Moreover, the slit waste etc. which generate | occur | produce when manufacturing this film can also be used as a collection | recovery raw material. Specifically, slit scraps and the like can be pelletized and added to the B layer of the present film as required in an amount of 5 to 70% by weight. The pelletizing method is generally a method in which a cut material is melt-extruded and then cut, but is not limited to this method.

  Although the thickness of the film of the present invention varies depending on the application to be used, a range of 10 to 200 μm is preferable, and a range of 20 to 150 μm is preferable from the viewpoint of film production and lamination with other substrates.

  In addition, the A layer, the B layer, and the C layer in the present invention contain other additives in addition to those described above from the viewpoint of preventing discoloration and improving weather resistance when used as a solar cell material. There may be.

As said other additive, a light stabilizer, a ultraviolet absorber, or a heat stabilizer can be mentioned.
As the light stabilizer, one that captures the active species at the start of photodegradation in the resin and prevents photooxidation can be used. Specifically, one or a combination of two or more selected from hindered amine compounds, hindered piperidine compounds, and the like can be used. Among these, it is preferable to use a hindered amine compound. In particular, it is preferable to mix a light stabilizer in the B layer in a range of 0.5 to 2.0 parts by weight with respect to 100 parts by weight of the resin component of the B layer because titanium oxide is stabilized and long-term weather resistance is imparted. If the addition amount is less than 0.5 parts by weight, the effect as a light stabilizer is insufficient, and if it exceeds 2.0 parts by weight, it is not preferable because it results from aggregation of inorganic particles such as bleed out and titanium oxide.

  As the above-mentioned ultraviolet absorber, it absorbs harmful ultraviolet rays in sunlight, converts them into innocuous heat energy in the molecule, and prevents the activation of active species that initiate photodegradation in the resin. Can be used. Specifically, benzophenone-based, benzotriazole-based, salicylate-based, acrylonitrile-based, metal complex-based, hindered amine-based, ultrafine titanium oxide (particle diameter: 0.01 μm to 0.06 μm) or ultrafine zinc oxide ( At least one type selected from the group consisting of inorganic ultraviolet absorbers (particle diameter: 0.01 μm to 0.04 μm) can be used.

Examples of the heat stabilizer include tris (2,4-di-tert-butylphenyl) phosphite, bis [2,4-bis (1,1-dimethylethyl) -6-methylphenyl] ethyl ester phosphorous acid. Acid, tetrakis (2,4-di-tert-butylphenyl) [1,1-biphenyl] -4,4'-diylbisphosphonite, and bis (2,4-di-tert-butylphenyl) penta Phosphorus heat stabilizers such as erythritol diphosphite; and lactone heat stabilizers such as a reaction product of 8-hydroxy-5,7-di-tert-butyl-furan-2-one and o-xylene Can do. Moreover, these can also use 1 type or 2 types or more. Among these, it is preferable to use a phosphorus heat stabilizer and a lactone heat stabilizer in combination.
The content of the light stabilizer, ultraviolet absorber, heat stabilizer and the like in the present invention is preferably in the range of 0.01% by weight to 5% by weight with respect to the resin composition weight of each layer.

  The film of the present invention is composed of A layer / B layer / C layer, and the lamination ratio is 3 to 30% for A layer, 60 to 96% for B layer, and 1.0 to 10% for C layer. Preferably there is. Moreover, the thickness of C layer is thinner than A layer, and the thickness of C layer needs to be 2/3 or less with respect to the thickness of A layer. Further, from the viewpoint of suppressing curling of the film, the thickness of the C layer is more preferably in the range of 1/5 to 2/3 of the thickness of the A layer.

  For example, when the film of the present invention is formed by the melt T-die molding method, when the melt-extruded sheet is cooled and cast on the cooling drum, it is rapidly cooled from the cooling drum surface, and the non-drum surface side is gradually cooled and crystallized. Curling may occur due to the difference between the two. Therefore, as described above, the thickness of the C layer on the slow cooling side is preferably thinner than the A layer on the quenching side. If a high-density ethylene-α-olefin copolymer is produced as a single film, although it has an excellent Young's modulus, crystallization of the non-drum surface that is gradually cooled with respect to the cast drum surface that is rapidly cooled may occur. Promoted. As a result, curling with the drum surface inside may occur, and film slippage in the take-up process or secondary processing may occur. Moreover, the deterioration due to ultraviolet irradiation is further rapid, and it may be inferior as a solar cell material.

  As described above, a high density resin is mixed in the A layer and the C layer and laminated at different lamination ratios, and a resin having a lower density than the A layer and the C layer is used for the B layer, thereby providing a firm film. In addition, film curl due to crystallization can be suppressed.

  The firm film of the present invention refers to a film having a high Young's modulus. The higher the Young's modulus, the easier it is to balance the tension when processing the film, and there is the merit of excellent handling. The value of Young's modulus is in the range of 150 to 500 MPa, preferably in the range of 150 to 400 MPa, more preferably in the range of 150 to 350 MPa. This is preferable.

  In addition, the film of the present invention can be used by laminating with another base material by a method such as an adhesive or heat fusion depending on the application. Examples of other base materials include aluminum foil, paper, and a thermoplastic resin film. The thermoplastic resin is not particularly limited as long as it is a thermoplastic resin capable of forming a film by melt extrusion. Preferred examples include polyethylene terephthalate (hereinafter abbreviated as PET), polyethylene-2,6-naphthalene dicarboxylate. Polyester such as polypropylene terephthalate, polybutylene terephthalate, poly-1,4-cyclohexylenedimethylene terephthalate, styrene resin such as polystyrene and acrylonitrile-styrene copolymer, polycarbonate, polyamide, polyether, polyurethane, polyphenylene sulfide, polyester Amides, polyether esters, polyvinyl chloride, polymethacrylic acid esters, modified polyphenylene ethers, polyarylate, polysulfone, polyether ether De, polyamideimide copolymer to the polyimide and those composed mainly or can be exemplified mixtures thereof and the like resins. Particularly in the present invention, polyester is preferable from the viewpoint of good dimensional stability and mechanical properties, and PET is particularly preferable.

  Hereinafter, the method for producing the polyolefin resin multilayer film of the present invention will be specifically described. In addition, the manufacturing method of the film of this invention is not limited to this.

As a resin used for the A layer, a resin composition in which 100 parts by weight of an ethylene-α-olefin copolymer having a density of 0.930 g / cm ³ or more and 5 to 20 parts by weight of a mixture of low density polyethylene and a propylene resin are mixed. It puts into a twin screw extruder and is compounded in the range of 180-280 degreeC.

As the resin used for the B layer, an ethylene-α-olefin copolymer having a density of less than 0.930 g / cm ³ is used as a main component or 100 parts by weight of the ethylene-α-olefin copolymer, and an average particle size of 0. 5 to 30 parts by weight of rutile-type titanium oxide particles coated with an inorganic oxide of 2 to 0.5 μm and 0.05 to 0.35% by weight of SumilizerGP as an antioxidant based on the resin composition weight In a range of 180 to 280 ° C. using a twin screw extruder.

As the C layer resin, an average particle diameter of 1 to 100 parts by weight of an ethylene-α-olefin copolymer having a density of 0.930 g / cm ³ or more, and 5 to 20 parts by weight of a mixture of a low density polyethylene and a propylene resin may be used. A resin composition obtained by mixing 0.1 to 10 parts by weight of 5 μm inorganic and / or organic particles is compounded in a range of 180 to 280 ° C. using a twin screw extruder.

  The resins thus prepared are each supplied to a single-screw melt extruder, and melt extrusion is performed in the range of 220 to 280 ° C., respectively. After removing foreign substances and coarse inorganic particles through a filter installed in the middle of the polymer tube, a multi-manifold type T die or a feed block installed on top of the T die is used for A layer / B layer / C layer type. Two-kind three-layer / or three-kind three-layer lamination is carried out and discharged from a T die onto a rotating metal roll with the A layer side being the metal roll surface side to obtain an unstretched sheet. At this time, it is preferable that the surface temperature of the rotating metal roll is controlled to 20 to 60 ° C., because adhesion to the metal roll of the A layer is not caused and the crystallinity is improved. Moreover, in order to make a molten polymer contact | adhere to a metal roll, it is preferable to use the method of spraying air from a nonmetallic roll side, or a nip roll.

  The A layer and / or C layer of the film of the present invention thus obtained are subjected to corona discharge treatment in air or in one or more atmospheres of nitrogen gas and carbon dioxide gas for bonding to other substrates. It is preferable that the surface is wound with a wetting tension of 35 mN / m or more.

  The polyolefin resin multilayer film of the present invention is suitable for food / beverages, pharmaceuticals / medical products, optical films, liquid crystal members, packaging materials for electronic / electrical parts, precision parts, etc., and solar cell materials. Can be used. The solar cell back surface protective sheet is a back sheet of a solar cell module, for example, a hydrolysis-resistant polyethylene terephthalate film (Toray Industries, Inc .: Lumirror X10S (registered trademark)) having a thickness of 25 to 250 μm and the present invention. A polyolefin-based multilayer laminated film is dry-laminated using a known adhesive.

  The solar cell back surface protective sheet is generally a plurality of plate solar cell elements between a light receiving side glass substrate and a back surface protective film, as described in, for example, Japanese Utility Model Laid-Open No. 6-38264. It is a back surface protective film in the structure which takes the structure which filled the sealing resin in the clearance gap inside. A plastic film having excellent mechanical properties, heat resistance, and moisture resistance is used for the back surface protective film.

  Hereinafter, the present invention will be described in detail by way of examples. The characteristics were measured and evaluated by the following methods.

(1) Density of resin Density was measured according to a density gradient tube method defined in JIS K7112-1980.

(2) Titanium oxide mixing amount 10 g of the resin composition or film is dissolved in xylene heated to 135 ° C. Titanium oxide, which is insoluble in xylene, is collected by centrifugation and collected by filtration, and the mixing amount is calculated by measuring the weight.

  At this time, in order to calculate the amount of titanium oxide mixed in the B layer of the three-layer laminated film, the cross section of the B layer with respect to the thickness of each laminated layer obtained by observing the film cross section with a scanning electron microscope at a magnification of 5,000 times Calculate according to thickness.

(3) Average particle size Particles before addition to the resin, or particles isolated by filtration from a resin, a film using a thermal solvent as described above, or an incompatible resin were analyzed using a transmission electron microscope (H-manufactured by Hitachi, Ltd.). 7100FA) and take a picture at 30,000 times. The equivalent circle diameter is measured for each particle on the photograph. For 1,000 particles, the equivalent circle diameter was determined, and the particle diameters were 0 to 0.05 μm, 0.05 to 0.10 μm, 0.10 to 0.15 μm, 0.55 to 0.60 μm.・ ・, And group, and find the particle size distribution of how many particles are included in each group. An intermediate value of each group and a representative diameter _{d i} of the group is (e.g., _d i = 0.125 .mu.m in a group of 0.10～0.15Myuemu), the particle number _{n i} in the group, the average by the following formula The particle diameter (weight average diameter) is calculated.
d = (Σ n _i · d _i ⁴ ) / (Σ n _i · d _i ³ ).

(4) Film Thickness and Thickness Composition Ratio The film thickness was measured at any 10 locations on the film using a dial gauge according to JIS K7130 (1992) A-2 method. The average value was divided by 10 to obtain the film thickness.

  The thickness of each layer in the case of a laminated film is as follows: the laminated film is embedded in an epoxy resin, the film cross section is cut out with a microtome, and the cross section is observed with a scanning electron microscope at a magnification of 5,000 times. The ratio was determined.

(5) Light reflectivity With a spectrophotometer (U-3410, manufactured by Hitachi, Ltd.) and a φ60 integrating sphere (130-0632, manufactured by Hitachi, Ltd.) and a 10-degree inclined spacer attached, a light reflectivity of 560 nm is measured on at least one side of the film. The average value measured three times was determined, and the value of the surface showing high light reflectance was defined as light reflectance.

(6) Young's modulus A sample film was cut into a size of 10 mm x 120 mm in accordance with JIS K7113 (1995/05/01 revised version). Using 10 cut sample films, measurement was performed under an atmosphere of 23 ° C., and the average value was calculated.

(7) Curl A sample film was cut into a 300 mm square, and the cut sample film was measured for 5 samples on the flat plate so that the cast surface was down, and the interface distance at which the film floated most from the lithographic plate was measured.

(8) Blocking resistance A sample film is cut out to 120 mm x 30 mm, and 10 sheets of the cast drum surface and the non-drum surface are overlapped at a position 40 mm from the end of the cut sample film. A 500 g weight was placed on the overlapped 40 mm × 30 mm surface and left in an oven at 40 ° C. and 84% RH for 24 hours. Then, it was left to cool in a room at 23 ° C. and 55% RH for 30 minutes.

Then, using a tensile and compression tester TG-500N (Minebea Co., Ltd.), the integrated average value of the shear peel force when taking two overlapping films and peeling them at a predetermined speed is the blocking shear force (g / 12 cm). ² ). The peeling speed was usually 300 mm / min.

(9) Ultraviolet-resistant UV deterioration promotion tester (I Super UV Tester SUV-W131: manufactured by Iwasaki Electric Co., Ltd.) was used under the following conditions. Ultraviolet irradiation (UV illuminance: 100 mW / cm ² , temperature and humidity: 60 ° C. × 50% RH) was carried out for 144 hours, the appearance of the film was visually observed, and the following determinations were made.
++: There is no discoloration of the resin, and no cracks or cracks are observed.
+: The resin is discolored, but no cracks or cracks are observed.
-: The resin is cracked and cracked.

(10) Low powderiness (antifouling property for film forming process)
In the process of forming the light reflecting film, the metal rolls used from the cast drum to the winder were observed for white powder and judged according to the following criteria. The determination was made after each film forming experiment was performed for 30 minutes, and after the experiment, the next experiment was performed after cleaning the metal roll.
++: No white powder adheres to all observed rolls.
+: Adherence of white powder was observed on a part of the observed roll.
-: The adhesion of the white powder was recognized by all the rolls observed.

(11) Manufacturing method of solar battery back sheet Two-component curing type adhesive (Dai Nippon Ink Chemical Co., Ltd. LX-903 / KL-) to biaxially stretched polyester film ("Lumirror" X10S 125 μm manufactured by Toray Industries, Inc.) 75 = 8/1) was applied at a solid coating thickness of 6 μm, dried at 80 ° C., and then superimposed on the corona-treated surface of the olefin film, and passed through a pair of pressure rolls to form a laminate. The laminated film was aged at a temperature of 40 ° C. for 72 hours to accelerate the curing reaction of the two adhesive layers, thereby forming a solar cell back surface protective sheet.

(12) The laminate obtained by the visual gap evaluation method (11) was sampled with a length of 10 m and a width of 1 m, and the number of bubbles (number / cm ² ) of 1 mm-1 mm or more at the adhesion interface was calculated visually.
++: The number of bubbles is within 10 (pieces / cm ² ) +: The number of bubbles is 10-30 (pieces / cm ² )
-: The number of bubbles is 30 (pieces / cm ² ) or more.

(13) Laminate strength The solar cell back surface protective sheet was sample cut at a width of 15 mm, peeled off between each layer of the laminate film, and peeled at 90 ° using Tensilon PTM-50 manufactured by ORIENTEC under room temperature conditions. The film was peeled at a peeling speed of 300 mm / min, and the polyolefin resin multilayer film according to the present invention was evaluated for the following judgment by evaluating the lack of breakage and the laminate strength.
++: No film breakage, laminate strength of 800 g / 15 mm or more +: No film breakage, laminate strength of 600 g / 15 mm or more, less than 800 g / 15 mm-: Film breakage occurred during peeling, and laminate strength was 600 g / Less than 15 mm.

(14) Partial discharge voltage The partial discharge voltage was measured for the approximately 50 mm square piece of the laminate under the following conditions, and the electrical insulation as a solar cell back surface protective sheet was evaluated.
Testing machine: KPD2050 (manufactured by Kikusui Industry Co., Ltd.)
Measurement environment conditions: Temperature 23 ° C, humidity 50%
Maximum applied voltage: 1.10 to 1.25 kV
Voltage application time: 22.0 s
Starting voltage: 0.71 to 0.98 kV
Annihilation voltage: 0.86 to 1.07 kV
++: Partial discharge voltage is 800 V or more +: Partial discharge voltage is 700 V or more and less than 800 V-: Partial discharge voltage is less than 700 V

(15) Sliding property The film is cut into a size of 100 mm × 50 mm, and two films are set so that the A layer and the C layer overlap each other, and JIS K7125 plastic-film and sheet friction coefficient test method (1999/08 / 20 revisions), 5 samples of the static friction coefficient were measured, and the average value was calculated. The following evaluation was performed from the calculated value.
++: Static friction coefficient is less than 1.0 +: Static friction coefficient is 1.0 or more and less than 1.5-: Static friction coefficient is 1.5 or more.

(16) Comprehensive evaluation The following comprehensive evaluation was performed by the evaluation of (12) to (14) of the solar cell back surface protection sheet by combining the evaluation results of the visual gap evaluation method, the laminate strength, and the partial discharge voltage.
++: All cases show ++ performance.
+: Two or more evaluations of ++.
-: ++ is 1 or less.

  Examples of the present invention and comparative examples will be described below.

Method for Producing Phosphorus-Phenolic Antioxidant Masterbatch A 90% by weight of ethylene-α-olefin copolymer having a density of 0.922 g / cm ³ and 10% by weight of phosphorus-phenolic antioxidant in a twin screw extruder After melt-kneading, the strand was cut to produce an antioxidant master batch A.

Production method of phenolic antioxidant master batch B Antioxidant masterbatch B was produced by the same method as antioxidant masterbatch A except that the antioxidant was a phenolic antioxidant.

Manufacturing method of hindered amine light stabilizer master batch C 90% by weight of ethylene-α-olefin copolymer having a density of 0.922 g / cm ³ and 10% by weight of hindered amine light stabilizer are melt-kneaded in a twin screw extruder. After that, the strand was cut to produce a hindered amine light stabilizer master batch C containing 10% by weight of a hindered amine light stabilizer.

Production method of titanium oxide master batch D 40% by weight of ethylene-α-olefin copolymer having a density of 0.922 g / cm ³ and 60% by weight of rutile titanium oxide having an average particle diameter of 200 nm surface-treated with an inorganic oxide After melt-kneading with a twin screw extruder, the strand was cut to produce a titanium oxide master batch D.

Example 1
As a resin used for the A layer, a linear low-polymer of ethylene-α-olefin copolymer having a density of 0.940 g / cm ³ and an MFR of 5 g / 10 min copolymerized with 4 mol% of 1-butene having 4 carbon atoms. 100 parts by weight of density polyethylene (hereinafter abbreviated as LLDPE), 3.5 parts by weight of low density polyethylene (hereinafter abbreviated as LDPE) with a density of 0.900 g / cm ³ and MFR of 7 g / 10 min and a propylene resin 14 parts by weight of a mixed resin composition of 10.5 parts by weight of homopolypropylene (hereinafter abbreviated as H-PP) having a density of 0.900 g / cm ³ and MFR of 8 g / 10 minutes was heated to 220 ° C. 2 It was put into a shaft extruder and compounded.

As the resin used for the B layer, phosphorus-phenolic antioxidant is used for 100 parts by weight of LLDPE having a density of 0.918 g / cm ³ and MFR of 5 g / 10 min copolymerized with 6 mol% of 1-octene having 6 carbon atoms. Agent Masterbatch-A was mixed with 0.5 parts by weight and compounded using a twin screw extruder heated to 220 ° C. As C layer resin, density 0.900 g / cm ³ , MFR 7 g / m, with respect to 100 parts by weight of LLDPE of ethylene-α-olefin copolymer having a density of 0.940 g / cm ³ and MFR 5 g / 10 min. 14 parts by weight of a mixed resin composition having a density of 0.900 g / cm ³ and a MFR of 8 g / 10 minutes as a propylene-based resin and 14 parts by weight of a mixed resin composition of 3.5 parts by weight of LDPE for 10 minutes and an average particle diameter of 2 μm A resin composition obtained by mixing 2 parts by weight of inorganic particles made of aluminum silicate ('Silton “JC30, manufactured by Mizusawa Chemical)” was compounded with a twin screw extruder heated to 220 ° C.

  The A layer, B layer, and C layer compound resins prepared in this way are each supplied to a uniaxial melt extruder, and melted at 220 ° C., respectively, so that A layer / B layer / C layer type multi-manifold type The film was extruded onto a casting drum maintained at 30 ° C., and cooled and solidified by blowing cold air of 25 ° C. from the non-drum surface side, so that the thickness composition ratio of each layer was 100% of the total thickness of the film. Layer / B layer / C layer = 15% / 75% / 10% A polyolefin resin multilayer film having a film thickness of 150 μm was obtained. The C layer of the multilayer film was subjected to corona discharge treatment and wound up with a surface wetting tension of 40 mN / m.

  As shown in Table 1, it can be seen from Table 3 that this film has cleared all the necessary requirements of the present invention and has excellent characteristics when used in a solar cell backsheet.

(Example 2)
As B layer composition, 100 parts by weight of resin composition is mixed with 0.5 parts by weight of master batch A of phosphorus-phenol antioxidant and 1.5 parts by weight of master batch C of hindered amine light stabilizer. did. Further, a polyolefin resin multilayer film having a film thickness of 100 μm was obtained in the same manner as the A layer except for the inorganic particles made of the aluminum silicate of the C layer. The C layer of the multilayer film was subjected to corona discharge treatment and wound up with a surface wetting tension of 40 mN / m.

  This film cleared all necessary requirements as shown in Table 1. Although the slipperiness is slightly poor, no problem in actual use is recognized, and it can be seen that it has excellent characteristics when used for a solar cell backsheet.

( Reference Example 3)
As the B layer composition, 100 parts by weight of the resin composition is mixed with 0.15 part by weight of a phosphorus-phenolic antioxidant masterbatch A, and further 33 parts by weight of a masterbatch D of rutile titanium oxide is mixed with a hindered amine. A polyolefin-based resin multilayer film having a film thickness of 150 μm was obtained in the same manner as in Example 1 except that 0.1 part by weight of master batch-C of the light stabilizer was mixed. The C layer of the multilayer film was subjected to corona discharge treatment and wound up with a surface wetting tension of 40 mN / m.

  As shown in Table 1, the present film has cleared all necessary requirements, and it can be seen that the film has excellent characteristics when used for a solar cell back sheet.

Example 4
As a resin used for the A layer, a density of 0.900 g / cm ³ with respect to 100 parts by weight of LLDPE having a density of 0.935 g / cm ³ and an MFR of 7 g / 10 min copolymerized with 6 mol% of 1-hexene having 6 carbon atoms. , LDPE 1.25 parts by weight of MFR 7 g / 10 min, and propylene-based resin with an ethylene copolymerization amount of 4 wt%, a density of 0.900 g / cm ³ , and an MFR 7 g / 10 min ethylene / propylene random copolymer (hereinafter referred to as the 5 parts by weight of 3.75 parts by weight of the mixed resin composition (abbreviated as EPC) was mixed and charged into a twin screw extruder heated to 220 ° C. to be compounded.

  As a C-layer resin, 1 part by weight of inorganic particles ('Silton “JC30, manufactured by Mizusawa Chemical Co., Ltd.) made of aluminum silicate having an average particle diameter of 2 μm was mixed with 105 parts by weight of the resin composition of the A layer, and 220 ° C. A polyolefin-based resin multilayer film having a film thickness of 150 μm was obtained in the same manner as in Example 1 except that the compound was introduced into a twin-screw extruder heated to a thickness and compounded, and corona discharge treatment was applied to the C layer of the multilayer film. The surface was wound up with a surface wetting tension of 40 mN / m.

  It can be seen from Table 3 that this film has cleared all necessary requirements as shown in Table 1 and has excellent characteristics when used in a solar cell backsheet.

( Reference Example 5)
As resin used for the A layer, 20 parts by weight of the LDPE and EPC mixed resin composition with respect to 100 parts by weight of the LLDPE of Example 4, and as the C layer resin, with respect to 120 parts by weight of the resin composition of the A layer, Except that a resin composition obtained by mixing 2 parts by weight of inorganic particles made of aluminum silicate having an average particle diameter of 2 μm ('Silton' JC30, manufactured by Mizusawa Chemical) was compounded in a twin screw extruder heated to 220 ° C. A polyolefin-based resin multilayer film having a film thickness of 150 μm was obtained in the same manner as in Example 4. The C layer of the multilayer film was subjected to corona discharge treatment and wound up with a surface wetting tension of 40 mN / m.

  It can be seen from Table 3 that this film has cleared all necessary requirements as shown in Table 1 and has excellent characteristics when used in a solar cell backsheet.

(Example 6)
In Example 1, a polyolefin-based resin multilayer film having a film thickness of 150 μm was prepared in the same manner as in Example 1 except that the thickness component ratio of layer A / layer B / layer C was 20% / 75% / 5%. Obtained. The C layer of the multilayer film was subjected to corona discharge treatment and wound up with a surface wetting tension of 40 mN / m.

  As shown in Table 1, this film has cleared all the necessary requirements of the present invention, and it can be seen that it has excellent characteristics when used in a solar cell backsheet.

(Comparative Example 1)
The layer A resin composition of Example 1 was supplied to a single-screw melt extruder, melted at 200 ° C., and extruded with a single-layer die. The film thickness of the single layer was 150 μm as in Example 1. The polyolefin resin film was obtained. Corona discharge treatment was performed on the non-drum surface side of the film, and the film was wound up with a surface wetting tension of 40 mN / m.

Since this film is a single layer having a high density resin composition with a density of 0.935 g / cm ³ , cracking of the film was observed in the UV resistance evaluation by Eye Super. Furthermore, the curl of the film was large, and the film was wound and wrinkled during secondary processing such as laminating. Table 2 shows the evaluation results of each physical property.

(Comparative Example 2)
In Example 1, without laminating the A layer, the resin composition of the B layer and the C layer was extruded by a two-type, two-layer multi-manifold type T die, and the thickness composition ratio was A layer / B layer / C layer. = 0% / 95% / 5% A polyolefin-based resin multilayer film having a film thickness of 150 μm was obtained in the same manner as in Example 1 except that the film thickness was 150%.

  Since this film consists of two layers, the titanium oxide added to layer B adheres to the metal roll during the film-forming process, fouling the process, and cracking of the film was observed in the UV resistance evaluation by iSuper. .

  (Comparative Example 3)
As a resin used for the A layer, 6% by weight of 1-butene was copolymerized, and the density was 0.912 g / cm. ³ Density of 0.900 g / cm for 100 parts by weight of LLDPE ³ , LDFR 0.75 part by weight of MFR 7 g / 10 min and density 0.900 g / cm as propylene resin ³ 3 parts by weight of a mixed resin composition of 2.25 parts by weight of H-PP with an MFR of 8 g / 10 min was mixed and charged into a twin screw extruder for compounding. As a resin used for the B layer, 7 wt% of 1-octene was copolymerized, and the density was 0.918 g / cm. ³ Biaxial extrusion heated to 220 ° C. after mixing 0.5 parts by weight of phosphorus-phenolic antioxidant masterbatch-A with 100 parts by weight of LLDPE and further 33 parts by weight of titanium oxide masterbatch D Compounded using the machine. As a C-layer resin, 8% by weight of 1-octene was copolymerized, and the density was 0.912 g / cm. ³ Density of 0.900 g / cm for 100 parts by weight of LLDPE ³ , LDFR 0.75 part by weight of MFR 7 g / 10 min and density 0.900 g / cm as propylene resin ³ , MFR 8g / 10min H-PP 2.25 parts by weight mixed resin composition 3 parts by weight and inorganic particles ('Silton "JC30, made by Mizusawa Chemical) made of aluminum silicate having an average particle diameter of 2 µm) 2 parts by weight The resulting resin composition was compounded with a twin screw extruder.

Each of the resins prepared as described above is supplied to a single-screw melt extruder, and melt-extruded in the range of 220 ° C., respectively. A multi-manifold type T die is used for A layer / B layer / C layer type. Three types and three layers were laminated to obtain a polyolefin resin multilayer film having a film thickness of 150 μm.

In this film, the density of the A layer and the C layer was low and the slipperiness was inferior, the air release property in the winding process was poor, and protrusions were frequently generated. Further, since the Young's modulus was low, it was difficult to control the tension during winding, and wrinkles were generated. Furthermore, it was also inferior in blocking resistance. Table 2 shows the evaluation results of each physical property.

(Comparative Example 4)
Instead of the LLDPE of the A layer and the C layer in Example 1, high density polyethylene having a density of 0.952 g / cm ³ was used. Furthermore, as a resin used for the B layer, 0.5 parts by weight of a phenolic antioxidant masterbatch B was mixed with 100 parts by weight of a density of 0.918 g / cm ³ LLDPE copolymerized with 7% by weight of 1-octene. Except that, a polyolefin resin multilayer film having a film thickness of 150 μm was obtained in the same manner as in Example 1. The C layer of the multilayer film was subjected to corona discharge treatment and wound up with a surface wetting tension of 40 mN / m. The film generated fine powder in the winding process, contaminated the film forming process and the laminating process, and scratched the film surface. Moreover, in the UV resistance evaluation by iSuper, cracking of the film was observed, and furthermore, since the film surface was large, many bubbles were generated at the laminate interface with the biaxially stretched polyester film. Table 2 shows the evaluation results of each physical property.

(Comparative Example 5)
A polyolefin system having a film thickness of 150 μm in the same manner as in Example 1 except that the LLDPE having the resin composition of the A layer and the C layer in Example 1 was changed to LLDPE having a density of 0.918 g / cm ³ and the LDPE was removed. A resin multilayer film was obtained. The C layer of the multilayer film was subjected to corona discharge treatment and wound up with a surface wetting tension of 40 mN / m.

  This film was inferior in slipperiness, and as a result, a number of protrusions that could not be repaired due to poor air removal occurred in the winding process. Moreover, in the manufacturing process of the solar battery backsheet, many bubbles were generated between the biaxially stretched polyester films. Table 2 shows the evaluation results of each physical property.

(Comparative Example 6)
A polyolefin resin multilayer film having a film thickness of 150 μm was obtained in the same manner as in Example 1 except that H-PP of the propylene resin was removed from the A layer and C layer resin compositions of Example 1. The C layer of the multilayer film was subjected to corona discharge treatment and wound up with a surface wetting tension of 40 mN / m. The film had a low Young's modulus and was not stiff, and the film was stretched and wrinkled due to the tension during winding during film formation and winding during lamination. Moreover, in the solar cell backsheet, the partial discharge voltage was low. Table 2 shows the evaluation results of each physical property.

(Comparative Example 7)
As resin used for the A layer, LLDPE 100 parts by weight of ethylene-α-olefin copolymer having a density of 0.952 g / cm ³ and MFR 5 g / 10 min copolymerized with 6 mol% of 1-hexene having 4 carbon atoms. In contrast, 20 parts by weight of a mixed resin composition having a density of 0.900 g / cm ³ , LDPE 5 parts by weight of MFR 7 g / 10 min and a propylene-based resin, and a density 0.95 g / cm ³ and MFR 8 g / 10 min H-PP 15 parts by weight. After mixing, the mixture was charged into a twin screw extruder heated to 220 ° C. and compounded.

The resin used for the B layer is a phenolic antioxidant master based on 100 parts by weight of LLDPE having a density of 0.918 g / cm ³ and MFR of 5 g / 10 min obtained by copolymerizing 6 mol% of 1-octene having 6 carbon atoms. 1.5 parts by weight of Batch B was mixed, and 33.0 parts by weight of Titanium Oxide Master Batch D was further mixed and compounded using a twin screw extruder heated to 220 ° C.

  As a C layer resin, a resin composition obtained by mixing 2 parts by weight of inorganic particles made of aluminum silicate having an average particle diameter of 2 μm ('Silton “JC30, manufactured by Mizusawa Chemical)” with 100 parts by weight of the A layer resin composition is heated to 220 ° C. It compounded with the made twin screw extruder.

  The A layer, B layer, and C layer compound resins prepared in this way are each supplied to a uniaxial melt extruder, and melted at 220 ° C., respectively, so that A layer / B layer / C layer type multi-manifold type Then, it was extruded onto a casting drum maintained at 30 ° C., and cooled and solidified by blowing cold air of 25 ° C. from the non-drum surface side, and the thickness composition ratio was A layer / B layer / C layer = 21% A polyolefin resin multilayer film having a film thickness of 150 μm / 70% / 9% was obtained. The C layer of the multilayer film was subjected to corona discharge treatment and wound up with a surface wetting tension of 40 mN / m.

  As shown in Table 1, film contamination due to bleedout of the antioxidant was observed in this film. Furthermore, as a result of the long-term weather resistance test, yellowing and cracking were observed. Table 2 shows the evaluation results of each physical property.

(Example 7)
The corona-treated surface of the sample film of Example 1 obtained in the present invention and a biaxially stretched polyester film (Lumirror X10S 188 μm manufactured by Toray Industries, Inc.) are a two-component curing type adhesive (LX-903 / manufactured by Dainippon Ink & Chemicals, Inc.) KL-75 = 8/1) was applied at a solid content coating thickness of 6 μm and dried to prepare a laminate.
The laminated film was aged at a temperature of 40 ° C. for 72 hours to promote the curing reaction of the two adhesive layers and the foaming in the adhesive layer, thereby obtaining the solar cell back surface protective sheet of the present invention.
This solar cell back surface protective sheet cleared the necessary requirements and was judged to be optimal. Table 3 shows the evaluation results of each physical property.

(Example 8)
The corona-treated surface of the sample film of Example 4 obtained in the present invention and a biaxially stretched polyester film (Lumirror X10S 125 μm manufactured by Toray Industries, Inc.) are two-component curing type adhesives (LX-903 / manufactured by Dainippon Ink and Chemicals, Inc.). KL-75 = 8/1) was applied at a solid content coating thickness of 6 μm and dried to prepare a laminate.
The laminated film was aged at a temperature of 40 ° C. for 72 hours to promote the curing reaction of the two adhesive layers and the foaming in the adhesive layer, thereby obtaining the solar cell back surface protective sheet of the present invention.
This solar cell back surface protective sheet cleared the necessary requirements and was judged to be optimal. Table 3 shows the evaluation results of each physical property.

Example 9
The corona-treated surface of the sample film of Example 6 obtained in the present invention and a biaxially stretched polyester film (Lumirror X10S 125 μm manufactured by Toray Industries, Inc.) are a two-component curing type adhesive (LX-903 / manufactured by Dainippon Ink and Chemicals, Inc.). KL-75 = 8/1) was applied at a solid content coating thickness of 6 μm and dried to prepare a laminate.
The laminated film was aged at a temperature of 40 ° C. for 72 hours to promote the curing reaction of the two adhesive layers and the foaming in the adhesive layer, thereby obtaining the solar cell back surface protective sheet of the present invention.

  This solar cell back surface protective sheet cleared the necessary requirements and was judged to be optimal. Table 3 shows the evaluation results of each physical property.

(Comparative Example 8)
The corona-treated surface of the sample film of Comparative Example 1 obtained in the present invention and a biaxially stretched polyester film (Lumirror X10S 188 μm manufactured by Toray Industries, Inc.) are a two-component curing type adhesive (LX-903 / manufactured by Dainippon Ink and Chemicals, Inc.). KL-75 = 8/1) was applied at a solid content coating thickness of 6 μm and dried to prepare a laminate.
The laminated film was aged at a temperature of 40 ° C. for 72 hours to promote the curing reaction of the two adhesive layers and the foaming in the adhesive layer, thereby obtaining the solar cell back surface protective sheet of the present invention.

  In the present solar cell back surface protective sheet, the film of Comparative Example 1 is curled, and deviation occurs during lamination. This meandered during laminating and caused air bubbles. Therefore, it was judged that it was not optimal as a solar cell back surface protection sheet. Table 3 shows the evaluation results of each physical property.

(Comparative Example 9)
The corona-treated surface of the sample film of Comparative Example 3 obtained in the present invention and a biaxially stretched polyester film (Lumirror X10S 188 μm manufactured by Toray Industries, Inc.) are a two-component curing type adhesive (LX-903 / manufactured by Dainippon Ink and Chemicals, Inc.). KL-75 = 8/1) was applied at a solid content coating thickness of 6 μm and dried to prepare a laminate.
The laminated film was aged at a temperature of 40 ° C. for 72 hours to promote the curing reaction of the two adhesive layers and the foaming in the adhesive layer, thereby obtaining the solar cell back surface protective sheet of the present invention.

  The solar cell back surface protective sheet was peeled and charged because the slipperiness of the film of Comparative Example 3 was not good, and foreign matters were mixed during lamination. Therefore, the laminate was judged to be not optimal because it had many bubbles, the partial discharge voltage of 1000 V was not achieved, and the film of Comparative Example 3 was cut during the laminate test. Table 3 shows the evaluation results of each physical property.

(Comparative Example 10)
The corona-treated surface of the sample film of Comparative Example 7 obtained in the present invention and a biaxially stretched polyester film (Lumirror X10S 125 μm manufactured by Toray Industries, Inc.) are a two-component curing type adhesive (LX-903 / manufactured by Dainippon Ink and Chemicals, Inc.). KL-75 = 8/1) was applied at a solid content coating thickness of 6 μm and dried to prepare a laminate.
The laminated film was aged at a temperature of 40 ° C. for 72 hours to promote the curing reaction of the two adhesive layers and the foaming in the adhesive layer, thereby obtaining the solar cell back surface protective sheet of the present invention.

  This solar cell back surface protective sheet was judged to be not optimal because the fine powder released from the film was lost and bubbles were generated frequently, and the film of Comparative Example 7 was cut during the lamination test. Table 3 shows the evaluation results of each physical property.

Claims (4)

A film having a three-layer structure of A layer / B layer / C layer, wherein the A layer and the C layer are mixed resin 5 of low density polyethylene and propylene resin with respect to 100 parts by weight of the ethylene-α-olefin copolymer. It consists of a resin composition in which ˜20 parts by weight are mixed, the B layer is mainly composed of an ethylene-α-olefin copolymer whose density is lower than that of the A layer and the C layer, and the density of the A layer and the C layer is 0.93. A polyolefin-based resin multilayer film in which the density is 0 g / cm ³ or more, the density of the B layer is less than 0.930 0 g / cm ³ , and the thickness of the C layer is 2/3 or less of the A layer. The polyolefin resin multilayer film according to claim 1, wherein 0.1 to 5 parts by weight of particles having an average particle diameter of 1 to 5 μm are contained in 100 parts by weight of the resin component of the A layer and / or 100 parts by weight of the resin component of the C layer. The resin component of the B layer contains 5 to 30 parts by weight of rutile-type titanium oxide particles coated with an inorganic oxide having an average particle diameter of 0.2 to 0.5 µm. Polyolefin resin multilayer film. The polyolefin resin multilayer film according to any one of claims 1 to 3, which is used as a solar cell back sheet.