TWI522239B - Cover film - Google Patents

Description

Cover film

The present invention relates to a cover film for use in a package of electronic parts.

With the miniaturization of electronic equipment, the electronic components used are also compact and high-performance, and in the assembly process of electronic devices, the components are automatically assembled on the printed circuit board. The surface mount electronic component is housed in a carrier tape which is formed in a shape of an electronic component and continuously formed with a pocket by thermoforming. After the electronic component is housed, a cover film as a cover material is superposed on the carrier tape, and both ends of the cover film are continuously heat-sealed in a longitudinal direction by a heated seal bar to obtain a package. In the case of the cover film, a polyester film base material which is biaxially stretched, a heat seal layer of a thermoplastic resin or the like is used. In terms of the carrier tape, mainly a polystyrene or a polycarbonate made of a thermoplastic resin is used.

In recent years, various types of electronic components such as capacitors, resistors, ICs, LEDs, connectors, and switching elements have been significantly miniaturized, reduced in weight, and thinned, and in order to take out the stored electronic components from the package, they are stripped. The required performance when covering the film has gradually become stricter than conventional. In particular, the peel strength at the time of peeling off the cover film from the carrier tape is continuously constant within a predetermined value range, and the electronic component to be housed becomes smaller and lighter in weight, and the electronic component jumps due to vibration during peeling. It is easy to always have problems with the assembly steps.

That is, when the components of the manufacturing steps of the electronic device are assembled, the cover film is peeled off by the automatic peeling device from the carrier tape, but if the peel strength is too strong, the cover film may be broken, and when it is too weak, When the conveyance body is transferred, the cover film is peeled off from the carrier tape, and the electronic component of the contents may fall off. In particular, with the rapid increase in assembly speed, the peeling speed of the cover film is also 0.1 second or less/the speed of production is extremely high, and when the peeling is performed, a great impact stress is applied to the cover film. As a result, the cover film is cut, causing a problem called "film breakage".

In the countermeasure against such film breakage, there is proposed a method in which a polypropylene or a nylon or a polyurethane is provided between a substrate such as a biaxially stretched polyester film and a sealant layer. A method of a layer excellent in impact or tear propagation resistance (see Patent Documents 1 to 3). Further, there is proposed a method in which the intermediate layer is a metallocene linear low density polyethylene (LLDPE) having a specific specific gravity, and the interlayer between the intermediate layer and the substrate layer is set to a low Young's modulus. A method of preventing stress propagation to a base material layer (refer to Patent Document 4). However, even if it is peeled off at a high speed of 100 m per minute by these methods, it is difficult to suppress film breakage.

Further, in the package in which the electronic component is housed, it is necessary to perform a baking treatment in order to remove moisture contained in the sealing resin. In order to improve the mass production of such electronic parts, it is necessary to increase the baking temperature and shorten the baking time. Recently, the cover film is heat-sealed in a carrier tape state, for example, starting at 60 ° C for 72 hours, or Baking treatment in an environment of 80 ° C for about 24 hours. In this case, the electronic component is attached to the thermal cover of the cover film, and assembly failure occurs when the component is assembled on the substrate. However, prior art problems with the attachment of such parts have not been adequately considered.

Prior technical literature Patent literature

Patent Document 1 Japanese Patent Laid-Open No. Hei 8-119373

Patent Document 2 Japanese Patent Laid-Open No. Hei 10-250020

Patent Document 3 Japanese Patent Laid-Open Publication No. 2000-327024

Patent Document 4 Japanese Patent Laid-Open Publication No. 2006-327624

The present invention has been made in view of the circumstances, and its main object is to provide a cover film which at least partially eliminates the adverse effects associated with the prior cover film.

More specifically, the subject of the present invention is to provide a cover film which is used for a cover film for a carrier tape such as polystyrene or polycarbonate. For example, in order to take out electronic parts, the peel strength is continuously continuous when the cover film is peeled off. And within a predetermined range, and even at high-speed peeling, the rise in peel strength is small, for example, when the vibration is peeled off, the minute electronic parts are tripped, or the film is broken at the time of high-speed peeling, which is caused by baking treatment. If the parts are attached, the problem in the assembly step will not occur.

The inventors of the present invention have conducted research on the above-mentioned problems, and as a result, first discovered a cover film which is provided with a heat seal layer composed of a specific thermoplastic resin having a specific mass average molecular weight, thereby achieving the object of overcoming the present invention. The cover film is completed while the present invention is completed.

That is, in one aspect of the present invention, there is provided a cover film comprising at least a substrate layer (A), an intermediate layer (B), a release layer (C), and a heat seal layer heat sealable on the carrier tape (D) The heat seal layer (D) is a styrene-acrylic copolymer having a mass average molecular weight of 5,000 to 20,000 as a main component.

In the foregoing, in one embodiment, the styrene-acrylic copolymer of the heat seal layer (D) is a resin having a glass transition temperature of 70 to 100 °C.

In another embodiment, the release layer (C) is a hydrogenated resin containing an aromatic vinyl-conjugated diene copolymer having an aromatic vinyl group content of 15 to 35% by mass as a main component. Further, the release layer (C) and/or the heat seal layer (D) contain a conductive material. In one embodiment, the conductive material is conductive particles, and the shape is composed of any one of needle-like or spherical particles or a combination thereof. For example, the conductive material is a carbon nanomaterial.

Furthermore, the present invention also includes an electronic component package in which the cover film is used as a cover material of a carrier tape having a thermoplastic resin as a main component.

According to the present invention, it is possible to obtain a cover film which uses a specific thermoplastic resin having a specific mass average molecular weight as a heat seal layer and forms a cover film for a carrier tape such as polystyrene or polycarbonate, so that, for example, in order to take out electrons The peel strength of the part when the cover film is peeled off is continuously within a predetermined range, and even at the time of high-speed peeling, the rise of the peel strength is small, the micro-electronic parts are broken by the vibration at the time of peeling, or the film is covered by the high-speed peeling. The problem of the assembly steps of the fracture and the attachment of the parts caused by the baking treatment does not occur.

The cover film of the present invention is formed in at least the order of the base material layer (A), the intermediate layer (B), the release layer (C), and the heat seal layer (D). An example of the constitution of the cover film of the present invention is shown in Fig. 1.

The substrate layer (A) is a layer containing a biaxially stretched polyester or a biaxially stretched nylon, and particularly preferably a biaxially oriented polyethylene terephthalate (PET) and a biaxially extended polyethylene naphthalate. Ester (PEN), biaxially stretched 6,6-nylon, 6-nylon, biaxially oriented polypropylene. In the case of two-axis extension PET, two-axis extension PEN, two-axis extension 6,6-nylon, 6-nylon, and biaxially oriented polypropylene, in addition to the commonly used materials, antistatic treatment may also be used. The electrostatic agent is coated or kneaded, or a material which has been subjected to corona treatment or easy subsequent treatment. When the base material layer is too thin, the tensile strength of the cover film itself is lowered, so that the "film breakage" tends to occur when the cover film is peeled off. On the one hand, when it is too thick, not only the heat sealability of the carrier tape is lowered, but also the cost is increased, so that a thickness of 12 to 25 μm can usually be suitably used.

In the present invention, the intermediate layer (B) may be laminated and provided on one surface of the base material layer (A) via an adhesive layer as needed. The resin constituting the intermediate layer (B) is soft and has moderate rigidity, and a linear low-density polyethylene (hereinafter abbreviated as LLDPE) excellent in tear strength at normal temperature can be suitably used. In particular, by using a resin having a density in the range of 0.900 to 0.925 (×10 ³ kg/m ³ ), extrusion of the intermediate layer resin from the end portion of the cover film is difficult to occur due to heat or pressure during heat sealing, so that it is not only The contamination of the trowel during heat sealing is less likely to occur, and the intermediate layer is softened by heat-sealing the cover film, and since the uneven contact of the heat seal can be alleviated, the peeling of the cover film is easy to obtain. strength.

In the LLDPE, there is a substance polymerized by a ziegler type catalyst and a substance polymerized by a metallocene type catalyst (hereinafter referred to as m-LLDPE). Since the m-LLDPE has a controlled molecular weight distribution in a narrow range, especially a high tear strength, it can be suitably used as the intermediate layer (B) of the present invention.

The above-mentioned m-LLDPE is a copolymer of an α-olefin having a carbon number of 3 or more, preferably a linear or branched, carbon-substituted chain of 3 to 18, and an α-olefin substituted with an aromatic nucleus. The linear monoolefin may, for example, be propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-decene, 1-dodecene, 1 -tetradecene, 1-hexadecene, 1-octadecene, and the like. Further, as the branched monoolefin, for example, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-ethyl-1-hexyl group can be exemplified. Alkene and the like. Further, examples of the monoolefin substituted with an aromatic nucleus include styrene and the like. These comonomers may be used alone or in combination of two or more and copolymerized with ethylene. In the copolymerization, a polyolefin such as butadiene, isoprene, 1,3-hexadiene, dicyclopentadiene or 5-ethylidene-2-northene may be copolymerized. Among them, 1-hexene and 1-octene which are used as a comonomer are excellent in tensile strength and excellent in cost, and can be suitably used.

The intermediate layer (B) has a thickness of usually 5 to 50 μm, preferably 10 to 40 μm. When the thickness of the intermediate layer (B) is less than 5 μm, the adhesion strength between the base layer (A) and the intermediate layer (B) may be insufficient, and when the cover film is heat-sealed to the carrier tape, it is difficult to obtain a tempering heat. The effect of uneven exposure. On the other hand, when it exceeds 50 μm, in order to make the total thickness of the cover film thick, it is difficult to obtain sufficient peel strength when heat-sealing the cover film on the carrier tape.

The cover film of the present invention is provided with a release layer (C) having a thermoplastic resin as a main component between the intermediate layer (B) and the heat seal layer (D). The thermoplastic resin to be used for the release layer (C) may, for example, be an acrylic resin, a polyester resin or an ethylene-vinyl acetate copolymer resin (hereinafter abbreviated as EVA); an ethylene-acrylic copolymer resin or an ethylene-methacrylic copolymer resin. , styrene-isoprene diblock copolymer resin, hydrogenated resin of styrene-isoprene diblock copolymer; styrene-butadiene diblock copolymer resin, styrene-butadiene di-embedded Hydrogenated resin of segment copolymer; hydrogenated resin of styrene-isoprene-styrene triblock copolymer (hereinafter referred to as SEPS); hydrogenated resin of styrene-butadiene-styrene triblock copolymer (below) SEBS); hydrogenated resin of styrene-butadiene random copolymer; hydrogenated resin of styrene-isoprene random copolymer. Among them, SEPS and SEBS composed of a styrene ratio of 15 to 35 mass% can be suitably used because the deviation of the peel strength is small when the cover film is peeled off.

The thickness of the release layer (C) is usually from 0.1 to 3 μm, preferably from 0.1 to 1.5 μm. When the thickness of the release layer (C) is less than 0.1 μm, sufficient peel strength may not be exhibited when the carrier tape is heat-sealed to the cover film. On the other hand, when the thickness of the release layer (C) exceeds 3 μm, there is a possibility that the peel strength is deviated when the cover film is peeled off. Further, as will be described later, the release layer (C) and the heat seal layer (D) are usually formed by a coating film, and in the case of being formed by a coating film method, the thickness after drying is referred to herein as a thickness.

The peeling layer (C) may contain a conductive material as needed, preferably contains conductive fine particles, and its surface resistivity is preferably from 1 × 10 ⁴ to 1 × 10 ¹² Ω. Examples of the conductive fine particles include conductive tin oxide particles, conductive zinc oxide particles, and conductive titanium oxide particles. Among them, tin oxide doped with antimony or phosphorus or gallium exhibits high conductivity and is less suitable for transparency reduction, so that it can be more suitably used. As the conductive tin oxide particles, the conductive zinc oxide particles, and the conductive titanium oxide particles, a spherical shape, a needle-like object, or a mixture of these may be used. In particular, in the case of using acicular tin oxide doped with antimony, a cover film having particularly excellent antistatic properties can be obtained. The amount of the conductive fine particles added is usually from 100 to 1,000 parts by mass, preferably from 200 to 800 parts by mass, per 100 parts by mass of the thermoplastic resin constituting the release layer (C). When the amount of the conductive fine particles added is less than 100 parts by mass, the surface resistivity of the heat seal layer (D) side of the cover film may not be 10 ¹² Ω or less, and when it exceeds 1000 parts by mass, the relative thermoplastic resin The amount is reduced, so that it is difficult to obtain sufficient peel strength due to heat sealing.

In the release layer (C), the electrically conductive material may also contain at least one carbon nanomaterial of carbon nanotubes or carbon nanofibers. Among them, a carbon nanotube having an aspect ratio of 10 to 10,000 is preferred. The carbon nanomaterial to the release layer (C) is added in an amount of 0.5 to 15 parts by mass, preferably 3 to 10 parts by mass, based on 100 parts by mass of the thermoplastic resin constituting the layer. In the case where the amount of addition is less than 0.5 parts by mass, the effect of providing conductivity by the addition of the carbon nanomaterial cannot be sufficiently obtained. On the other hand, when it exceeds 15 parts by mass, not only an increase in cost but also a decrease in transparency of the cover film is caused. Therefore, it is difficult to inspect the storage parts through the cover film.

In the cover film of the present invention, a heat seal layer (D) having a thermoplastic resin as a main component is formed on the surface of the release layer (C), and a styrene-acrylic copolymer is used as the thermoplastic resin. The styrene-acrylic copolymer is a copolymer containing a styrene monomer and a (meth)acrylic monomer as essential components, and examples of the styrene monomer include styrene and α-methylbenzene. Ethylene, o-methyl styrene, m-methyl styrene, p-methyl styrene, p-phenyl styrene, etc., particularly preferably styrene. These styrene monomers may be used singly or in combination of two or more. The (meth)acrylic monomer may, for example, be an acrylate such as methyl acrylate, ethyl acrylate, propyl acrylate or butyl acrylate; methyl methacrylate, ethyl methacrylate or propyl methacrylate; A methacrylate such as butyl methacrylate or cyclohexyl methacrylate. These (meth)acrylic monomers may be used singly or in combination of two or more. Further, in addition to the styrene monomer and the (meth)acrylic monomer, a small amount of another monomer copolymerizable with the monomers may be copolymerized.

The resin containing the styrene-acrylic copolymer as a main component is extremely excellent in heat sealability with respect to polystyrene or polycarbonate which is a material constituting the carrier tape, and particularly, a mass average molecular weight of 5,000 to 20,000 can be used. A resin having a styrene-acrylic copolymer as a main component of 10,000 to 20,000 is preferable. Since the mass average molecular weight is less than 5,000, the viscous property is generated, so that the storage member adheres to the heat seal layer (D), which is a cause of assembly problems. On the other hand, when the mass average molecular weight exceeds 20,000, when the peeling speed is increased, the peel strength is remarkably increased, which causes a fracture. Further, the glass transition temperature of the styrene-acrylic copolymer is preferably from 70 ° C to 100 ° C. When it is less than 70 ° C, in a conveyance environment such as shipping, there is a fear that the storage part adheres to the hot cover of the cover film.

The heat seal layer (D) has a thickness of 0.1 to 5 μm, preferably 0.1 to 3 μm, more preferably 0.1 to 0.5 μm. When the thickness of the heat seal layer (D) is less than 0.1 μm, there is a case where the heat seal layer (D) does not exhibit sufficient peel strength. On the other hand, when the thickness of the heat seal layer (D) exceeds 5 μm, not only the cost is increased, but also the deviation of the peel strength is liable to occur when the cover film is peeled off.

Further, in the cover film of a suitable embodiment of the present invention, an inorganic filler is added to the heat seal layer (D). The cover film of the present invention is in the environment of being heat-sealed on the surface of the carrier tape on which the electronic component is mounted, in order to remove moisture contained in the sealing resin, in an environment of 60 ° C for 72 hours or 80 ° C. The baking treatment is carried out under the conditions of about 24 hours, and in this case, when the electronic component of the content is attached to the cover film, the step of disassembling the cover film to assemble the electronic component becomes a problem. In the cover film of the present invention, since the deviation of the peel strength is small when the cover film is peeled off, and the adhesion of the contents to the heat seal layer (D) of the electronic component can be controlled at a high temperature of 60 to 80 ° C, The problem of adhesion of such an electronic component is considerably eliminated, but if an inorganic filler is added to the heat seal layer (D), the adhesion can be more reliably achieved. Here, the inorganic filler to be added may be any one as long as it is intended to achieve the above-mentioned anti-adhesion, and examples thereof include talc particles in a spherical or pulverized shape, cerium oxide particles, alumina particles, mica particles, and calcium carbonate. , magnesium carbonate and the like. Further, in order to maintain the transparency of the cover film, the inorganic filler is formed to have a median diameter (D50) of less than 200 nm, and is contained, for example, in an amount of 10 to 50 parts by mass.

Further, in the cover film of the present invention, the conductive layer is contained in the release layer (C), but in an embodiment, the heat seal layer (D) is also made to contain a conductive material, and the surface resistivity thereof may also be formed. It is preferably 1 × 10 ⁴ to 1 × 10 ¹² Ω. Alternatively, in other embodiments, the peeling layer (C) may not contain a conductive material, and the conductive material may be contained only in the heat seal layer (D). Here, the case where the type of the conductive material contained therein or the amount thereof is contained in the peeling layer (C) is also the same as described above.

The method for producing the above-mentioned cover film is not particularly limited, and a general method can be used. For example, an adhesive such as a polyurethane, a polyester, a polyolefin, or a polyethyleneimide is applied to the surface of the substrate layer (A) such as a biaxially stretched polyester film in advance, thereby being an intermediate layer. (B) A resin composition containing, for example, m-LLDPE as a main component, which is extruded from a T-die and coated on a coated surface of an anchor coat agent to form a substrate layer (A) A two-layer film formed with the intermediate layer (B). Further, on the surface of the intermediate layer (B), the release layer (C) is applied by, for example, a gravure coater, a reverse coater, an applicator coater, an air knife coater, a Meyer bar coater, a dipping coater, or the like. Coating film. In this case, it is preferred to perform corona treatment or ozone treatment on the surface of the intermediate layer (B) before the coating, and it is particularly preferable to carry out corona treatment. Further, on the release layer (C) applied to the intermediate layer (B), the resin composition constituting the heat seal layer (D) is coated, for example, by a gravure coater, a reverse coater, an applicator coater, or an air knife. A coating film can be obtained by coating a film with a machine, a Meyer bar coater, a dipping coater, or the like.

In another method, the intermediate layer (B) is formed into a film by a T-die casting method or an inflation method in advance, and is bonded to the base material layer (A) via a polyurethane, a polyester, or the like. A film composed of a base material layer (A) and an intermediate layer (B) can be obtained by applying a release agent to the surface of the intermediate layer (B) by using an adhesive of a polyolefin or the like and then dry-bonding the film. With the heat seal layer (D), a cover film for the purpose can be obtained.

Further, in other methods, a desired cover film can be obtained by the sand layer method. The film constituting the first intermediate layer is also formed into a film by a T-die casting method or an expansion method. Next, a resin composition containing molten m-LLDPE as a main component is supplied between the film of the first intermediate layer and the film of the base layer (A) to form a second intermediate layer, which is laminated to obtain a purpose. After the film of the base layer (A) of the cover film and the intermediate layer (B) composed of the first intermediate layer and the second intermediate layer, a release layer (C) is further applied to the surface of the intermediate layer (B) side. With the heat seal layer (D), a film for the purpose can be obtained. In the case of this method, as in the case of the above method, generally, an adhesive is applied to the surface of the side of the film layer of the base material layer (A).

In addition to the foregoing steps, antistatic treatment may be performed on at least one side of the cover film as needed. The surfactant type such as an anionic, cationic, nonionic or betaine can be applied as an antistatic agent by a roll coater, a lip coater, a spray or the like using a gravure roll. An antistatic agent or a conductive material dispersed in a polymer type antistatic agent and a binder. Further, in order to uniformly apply the antistatic agents, it is preferred to perform corona discharge treatment or ozone treatment on the surface of the film before the antistatic treatment, and particularly preferably corona discharge treatment.

The cover film is used as a cover material for a carrier tape belonging to a storage container of an electronic component. The carrier tape refers to a belt having a width of about 8 mm to 100 mm for accommodating the pocket portion of the electronic component. In the case where the cover film is heat-sealed as a cover material, the material constituting the carrier tape is not particularly limited, and a commercially available product may be used. For example, polystyrene, polyester, polycarbonate, polyvinyl chloride, or the like may be used. . In the case where an acrylic resin is used for the heat seal layer, a combination of a carrier tape of polystyrene and polycarbonate can be suitably used. The carrier tape provides electrical conductivity by kneading carbon black or carbon nanotubes in the resin; compounding the antistatic agent or the conductive material, or antistatic of the surfactant type by coating on the surface The conductive agent such as polypyrrole or polythiophene is dispersed in a coating liquid of an organic binder such as acrylic acid to provide an antistatic property.

In the package in which the electronic component is housed, for example, after the electronic component is housed in the electronic component storage portion of the carrier tape, the cover film is used as a cover material, and both edges of the cover film in the longitudinal direction are continuously heat-sealed and packaged, and wound by Available from reel. By packaging in this form, electronic parts and the like can be stored and transported. The package that is stored in an electronic component or the like is used as a sprocket hole for transporting a carrier tape provided on the edge of the carrier tape in the longitudinal direction, and is conveyed while intermittently peeling off the cover film. The component assembly device removes the presence, direction, and position of the electronic component and the like, and assembles the substrate.

Further, when the cover film is torn off, if the peel strength is too small, peeling occurs from the carrier tape, and the storage member may be peeled off. If it is too large, peeling from the carrier tape may become difficult, and at the same time, the cover film may be peeled off. There is a fear that the crucible is broken, so that it is preferably heat-sealed at 120 to 220 ° C, preferably having a peel strength of 0.05 to 1.0 N, and preferably less than 0.4 N in terms of deviation in peel strength.

[Examples]

The present invention will be described in further detail by way of examples, but the invention is not limited thereto.

[Materials used]

In the examples and comparative examples, the following raw materials were used for the base material layer (A), the intermediate layer (B), the release layer (C), and the heat seal layer (D).

(Substrate layer (A))

Biaxially extended polyethylene terephthalate film (manufactured by Toyobo Co., Ltd.), thickness 12μm

(middle layer (B))

m-LLDPE: LL-UL (film manufactured by Futamura Chemical Co., Ltd.), thickness 40 μm

(Resin of layer (C))

(c-1) Resin: Tuftec H1041 (manufactured by Asahi Kasei Chemicals Co., Ltd.), hydrogenated resin (SEBS) of styrene-butadiene-styrene triblock copolymer, styrene ratio 30% by mass

(c-2) Resin: Septon 2007 (manufactured by Kuraray Co., Ltd.), hydrogenated resin (SEPS) of styrene-isoprene-styrene triblock copolymer, styrene ratio of 30% by mass

(c-3) Resin: Tuftec H1051 (manufactured by Asahi Kasei Chemicals Co., Ltd.), hydrogenated resin (SEBS) of styrene-butadiene-styrene triblock copolymer, styrene ratio 42% by mass

(conductive material formulated in the peeling layer (C))

(c-4) Conductive material: FSS-10T (manufactured by Ishihara Sangyo Co., Ltd.), erbium-doped tin oxide, number average long diameter 2 μm, toluene dispersion type

(c-5) Conductive material: SNS-10T (manufactured by Ishihara Sangyo Co., Ltd.), spherical yttrium-doped tin oxide, median diameter (D50) 100 nm, toluene dispersion type

(c-6) Conductive material: DCNT-263D-1 (manufactured by Datong Coating Co., Ltd.), carbon nanotubes, 10 to 20 nm in diameter, and an average number of long diameters of 0.1 to 10 μm

(resin of heat seal layer (D))

(d-1) Resin: Daikalac S-7069A (manufactured by Datong Chemical Industry Co., Ltd.), styrene-acrylic copolymer resin, mass average molecular weight 9000, glass transition temperature 80 °C

(d-2) Resin: Daikalac S-7069B (manufactured by Datong Chemical Industry Co., Ltd.), styrene-acrylic copolymer resin, mass average molecular weight 12000, glass transition temperature 80 °C

(d-3) Resin: Daikalac S-7069C (manufactured by Datong Chemical Industry Co., Ltd.), styrene-acrylic copolymer resin, mass average molecular weight 16000, glass transition temperature 80 °C

(d-4) Resin: Daikalac 8020 (manufactured by Datong Chemical Industry Co., Ltd.), styrene-acrylic copolymer resin, mass average molecular weight 8000, glass transition temperature 90 °C

(d-5) Resin: Daikalac 8000 (manufactured by Datong Chemical Industry Co., Ltd.), styrene-acrylic copolymer resin, mass average molecular weight 9000, glass transition temperature 66 ° C

(d-6) Resin: Daikalac S-7069D (manufactured by Datong Chemical Industry Co., Ltd.), styrene-acrylic copolymer resin, mass average molecular weight 22000, glass transition temperature 80 °C

(d-7) Resin: Daikalac 8085 (manufactured by Datong Chemical Industry Co., Ltd.), acrylic resin, mass average molecular weight 4000, glass transition temperature 90 °C

(d-8) Resin: Dianal BR-113 (manufactured by Mitsubishi Rayon Co., Ltd.), acrylic resin, mass average molecular weight 30000, glass transition temperature 75 ° C

(Inorganic filler added to heat seal layer (D))

(d-9) Inorganic filler: MEK-ST-ZL (manufactured by Nissan Chemical Co., Ltd.), cerium oxide filler, median diameter (D50) 100 nm

(Electrically conductive material added to the heat seal layer (D))

(d-10) Conductive material: FSS-10T (manufactured by Ishihara Sangyo Co., Ltd.), acicular yttrium doped tin oxide, number average long diameter 2 μm, toluene dispersion type

[Example 1]

On the surface of a biaxially stretched polyester film having a thickness of 12 μm, a polyester-based tackifier is applied by a gravure method, and the thickness of [m-LLDPE] polymerized by the metallocene catalyst is dry-processed. A 40 μm film was laminated to obtain a laminated film composed of a biaxially stretched polyester layer (base material layer) and an m-LLDPE layer (intermediate layer). Next, after performing corona treatment on the m-LLDPE side of the film, mixing [(c-1) resin] dissolved in cyclohexane and yttrium-doped tin oxide dispersion [(c-4) conductive material] The solid content ratio was changed to (c-1):(c-4)=100:300 parts by mass, and on the surface subjected to the corona treatment, the film was coated by a gravure method to have a dry thickness of 0.4 μm, and a release layer was formed. Further, a random copolymer [(d-1) resin] and [(d-9) inorganic compound of a styrene resin and a methacrylic resin are mixed as a heat seal layer on the coating film surface of the release layer. a filler] so that the mass ratio of the solid component is (d-1): (d-9) = 100:50; a solution of the solution dissolved in MEK is applied by a gravure method so that the thickness after drying becomes 0.6 μm. A cover film for a carrier tape having antistatic properties.

[Examples 2 to 10, Comparative Examples 4 to 6]

A cover film was produced in the same manner as in Example 1 except that the raw materials such as the resins described in Tables 1 and 2 were used, and the release layer and the heat seal layer were formed.

[Comparative Example 1]

A cover film was produced in the same manner as in Example 1 except that the peeling layer and the heat seal layer were sequentially formed on the base material layer having a thickness of 50 μm without providing the intermediate layer.

[Comparative Example 2]

A cover film was produced in the same manner as in Example 1 except that the intermediate layer and the heat seal layer were formed using the raw materials such as the resin described in Table 2, except that the release layer was not provided.

[Comparative Example 3]

A cover film was produced in the same manner as in Example 1 except that the heat seal layer was not provided, and the raw material such as the resin described in Table 2 was used to form the intermediate layer and the release layer.

[Evaluation method]

The coating film for a carrier tape of an electronic component produced in each of the examples and the comparative examples was evaluated as described below. These results are shown in Tables 1 and 2, respectively.

(1) Fog value

The haze value was measured in accordance with the measurement method A of JIS K 7105:1998 using an integrating sphere type measuring device. The results are shown in the columns of the haze values in Tables 1 and 2.

(2) Sealing

Use taping machine (Shibuya Industrial Co., Ltd., ETM-480) to seal head width 0.5mmx2, seal head length 32mm, sealing pressure 0.1MPa, feed length 4mm, sealing time 0.1 second × 8 times, at sealing 镘 temperature 140 ° C to 190 ° C, at a 10 ° C interval, a 5.5 mm wide cover film is heat-sealed to a polyethylene carrier tape of 8 mm width (manufactured by Electrochemical Industries, Inc.), and a carrier tape made of polystyrene (Electrochemical Industry Co., Ltd.) system). After being allowed to stand in an environment of a temperature of 23 ° C and a relative humidity of 50% for 24 hours, the cover film was peeled off at a speed of 300 mm per minute and a peeling angle of 170 to 180° in an environment of the same temperature of 23 ° C and a relative humidity of 50%.镘 The temperature is 140 ° C to 190 ° C, and the average peel strength at the time of heat sealing at intervals of 10 ° C is in the range of 0.3 to 0.9 N, which is represented by "excellent", although there is a seal having an average peel strength of 0.3 to 0.9 N. Temperature range, except that the sealing enthalpy temperature is 140 ° C to 190 ° C, and the average peel strength at the time of heat sealing at 10 ° C intervals exceeds the sealing 镘 temperature range of 0.3 to 0.9 N, which is expressed as "good", even in any seal 镘The matter in which the average peel strength in the temperature is not in the range of 0.3 to 0.9 N is represented by "poor". The results are shown in the columns of the seals of Tables 1 and 2.

(3) Deviation of peel strength

The heat-sealing was performed so that the peeling strength with respect to the polystyrene carrier tape (manufactured by Denki Kagaku Kogyo Co., Ltd.) was 0.4 N. The cover film was peeled off under the same conditions as the above (2). When the cover film was peeled off at a peeling direction of 100 mm, the deviation of the peel strength was derived from the obtained chart. The deviation of the peeling strength of 0.2N or less is marked as "excellent", the thing of 0.2 to 0.4N is marked as "good", the substance of more than 0.4N is marked as "poor", and the article having a peeling strength of less than 0.4N is marked. It is "not evaluated". The results are shown in the deviation column of the peeling of Tables 1 and 2.

(4) peeling speed dependence of the cover film

The heat-sealing was performed so that the peeling strength with respect to the polystyrene carrier tape (manufactured by Electric Chemical Industry Co., Ltd.) was 0.4 N. The cover film was peeled off under the same conditions as the (2) sealing property. The peeling speed was changed to 2000 mm per minute, and the average peeling strength was from 0.4 to 0.5 N, which was "excellent", from 0.5 to 0.6 N, "good", and those larger than 0.6 N were "poor". The results are shown in the deviation column of the peeling of Tables 1 and 2.

(5) Fracture resistance of the cover film

The heat-sealing was performed so that the peeling strength with respect to the polystyrene carrier tape (manufactured by Denki Kagaku Kogyo Co., Ltd.) was 1.0 N. The cover film was peeled off under the same conditions as the above (2) sealing property. A carrier tape sealed with a cover film of a length of 550 mm was cut, and the bottom of the bag portion of the carrier tape was adhered to the vertical wall to which the adhesive tape on both sides was attached. A cover film of 50 mm was peeled off from the upper side of the carrier tape for adhering, and the cover film was clamped by a jig, and a weight of 1000 g was attached to the jig. Thereafter, when the weight of the scale is naturally dropped, the film which is not broken in the sample of 50 samples in 50 samples is represented by "excellent", and the film of 1 to 5 samples is broken in 50 samples. The object is indicated by "good", and the object with 5 or more fractures is indicated by "bad". The results are shown in the columns of the film breakage resistance of Tables 1 and 2.

(6) Time stability of peel strength

In the same conditions as the above (3) sealing property, heat sealing was performed so that the peeling strength became 0.4N. It was put into the environment at a temperature of 60 ° C, a relative humidity of 10%, a temperature of 60 ° C, and a relative humidity of 95% for 7 days, and after taking out, it was placed in an environment of a temperature of 23 ° C and a relative humidity of 50% for 24 hours, at the same temperature. The peel strength was measured in an environment of 23 ° C and a relative humidity of 50%. The measurement of the peel strength was carried out under the same conditions as the above (3) sealing property. The product having an average peel strength of 0.4 ± 0.1 N is expressed as "excellent", and the product having a range of 0.4 ± 0.2 N is expressed as "good", and the product having an average peel strength other than the above is expressed as "poor". The results are shown in the columns of the seals of Tables 1 and 2.

(7) Baking resistance

On the heat seal layer of the horizontally stretched cover film, 50 electronic components (LED: 1.6 mm × 0.8 mm manufactured by Stanley Co., Ltd.) were placed, and the mixture was placed in an environment of 80 ° C for 24 hours. After being taken out from the environment at 80 ° C, it was allowed to stand for 1 hour in an environment of a temperature of 23 ° C and a relative humidity of 50%, and the cover film was reversed under the same temperature of 23 ° C and a relative humidity of 50%, and the electronic parts were counted and attached to the cover film. The number. The number of parts attached to the cover film is represented by "excellent" in the range of 0 to 5, "good" in the range of 6 to 10, and "bad" in more than 10 items. The results are shown in the column of baking resistance of Tables 1 and 2.

(8) Surface resistivity

The surface resistivity of the surface of the heat seal layer was measured by a method of JIS K 6911 using a Hiresta UP MCP-HT450 of Mitsubishi Chemical Corporation at an ambient temperature of 23 ° C, an ambient humidity of 50% RH, and an applied voltage of 10 V. The results are shown in the column of surface resistivity of Tables 1 and 2.

1. . . Cover film

2. . . Substrate layer (A)

3. . . Priming layer

4. . . Middle layer (B)

5. . . Peeling layer (C)

6. . . Heat seal layer (D)

Fig. 1 is a cross-sectional view showing an example of a layer structure of a cover film of the present invention.

1. . . Cover film

2. . . Substrate layer (A)

3. . . Priming layer

4. . . Middle layer (B)

5. . . Peeling layer (C)

6. . . Heat seal layer (D)

Claims (6)

A cover film comprising at least a base material layer (A), an intermediate layer (B), a release layer (C) and a heat seal layer (D) heat sealable on a carrier tape, the base material layer (A) Containing a biaxially stretched polyester, the intermediate layer (B) comprises a linear low density polyethylene, and the release layer (C) comprises a styrene-isoprene-styrene triblock having a styrene ratio of 15 to 35 mass% a hydrogenated resin of a copolymer or a hydrogenated resin of a styrene-butadiene-styrene triblock copolymer having a styrene ratio of 15 to 35 mass%, and a heat seal layer (D) containing a mass average of 5,000 to 20,000 The molecular weight styrene-acrylic copolymer is used as a main component, the base layer (A) has a thickness of 12 to 25 μm, the intermediate layer (B) has a thickness of 10 to 40 μm, and the release layer (C) has a thickness of 0.1 to 0.1. The thickness of the heat seal layer (D) is 1.5 to 5 μm. The cover film of claim 1, wherein the styrene-acrylic copolymer of the heat seal layer (D) is a resin having a glass transition temperature of 70 to 100 °C. The cover film of claim 1, wherein the release layer (C) and/or the heat seal layer (D) contain a conductive material. The cover film of claim 3, wherein the conductive material is conductive fine particles, and the shape is formed by any one of needle-like or spherical particles or a combination thereof. The cover film of claim 3 or 4, wherein the conductive material is a carbon nanomaterial. An electronic component package using the cover film according to any one of claims 1 to 5 as a cover material of a carrier tape obtained by using a thermoplastic resin as a main component.