JP4805612B2 - Cover film - Google Patents

Description

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

Along with the downsizing of electronic devices, electronic components used are also becoming smaller and higher performance. In the assembly process of electronic equipment, parts are automatically mounted on a printed circuit board. Taping packaging is generally performed in order to sequentially supply electronic components during automatic mounting. In taping packaging, electronic parts etc. are stored in the recesses of the forming tape with recesses for storing electronic parts at regular intervals, and then the cover film is overlapped on the upper surface of the forming tape as a cover material with seal bars etc. Is heat-sealed in the length direction. Conventionally, as a cover film material, a biaxially stretched PET film and a sealant layer laminated with a hot melt layer are used.

Such a cover film and a component storage tape having a recess made of polystyrene, polyvinyl chloride, polycarbonate, or the like, such as a component stored in a carrier tape, is automatically used when mounting a component in a manufacturing process such as an electronic device. After being peeled off by the peeling device, the parts are taken out by an automatic take-out machine and then mounted on a circuit board or the like.

With the rapid increase in mounting speed, the peeling speed of the cover film is also extremely high at 0.1 seconds or less / tact. At the time of peeling, a large impact stress is applied to the cover film. As a result, there is a problem called “film cut” in which the cover film is cut.

As a countermeasure against film breakage, a method of providing a layer excellent in impact resistance and tear propagation resistance, such as polypropylene, nylon and polyurethane, between a base material such as a biaxially stretched polyester film and a sealant layer (see Patent Documents 1 to 4) ), And a method of multilayering the base material layer (see Patent Document 5). Patent Documents 6 and 7 relate to a cover film having a sealant layer composed of a copolymer of styrenic hydrocarbon and conjugated diene hydrocarbon, ethylene-α-olefin, and high-impact polystyrene. The method is not considered at all.
JP-A-8-119373 Japanese Patent Laid-Open No. 10-250020 JP 2000-142788 A JP 2000-327024 A Japanese Patent Laid-Open No. 9-156684 Special table 2003-508253 gazette JP 2004-244115 A

The present invention provides a cover film that is excellent in heat sealability, stability of peel strength, and transparency, and is less likely to cause “film breakage” during high-speed peeling.

The present invention employs the following means in order to solve the above problems.
(1) It has a biaxially stretched polyethylene terephthalate layer, a polyolefin resin layer, and a sealant layer, the sealant layer has a thickness of 10 μm or more, and comprises the following components (a) to (d): ) Is a cover film having a total of 50% by mass or more of styrene-based hydrocarbons contained in a total of 100% by mass. Component (a) is a styrene-based hydrocarbon and conjugated diene copolymer comprising 50 to 70% by mass of 65% by mass to less than 90% by mass of styrene hydrocarbon and 10% to less than 35% by mass of conjugated diene hydrocarbon. It is. Component (b) is a styrene hydrocarbon and conjugated diene block copolymer consisting of 10% to less than 50% by weight of styrene hydrocarbon and 50% to less than 90% by weight of conjugated diene hydrocarbon. %. Component (c) is an ethylene-α-olefin random copolymer of 10 to 35% by mass.
It is. Component (d) is 5 to 25% by mass of high impact polystyrene.
(2) A cover film in which an antistatic treatment is performed on at least one side of the cover film of (1).
(3) An electronic component packaging container using the cover film according to (1) or (2).

The cover film of the present invention is excellent in heat sealability, stability of peel strength, and transparency, and can reduce the occurrence of “film breakage” during high-speed peeling.

The biaxially stretched polyethylene terephthalate layer is a layer using biaxially stretched polyethylene terephthalate. As the biaxially stretched polyethylene terephthalate, a commercially available one can be used, and one obtained by applying or kneading an antistatic agent for antistatic treatment, or one subjected to corona treatment or easy adhesion treatment. It can also be used. When the biaxially stretched polyethylene terephthalate layer is too thin, it tends to cause “film breakage” when the cover film is peeled off. On the other hand, if it is too thick, the adhesiveness of the cover film tends to be lowered. Can be used.

The polyolefin resin layer is a layer using a polyolefin resin. The polyolefin resin is a resin containing an olefin as a component. For example, low density polyethylene, linear low density polyethylene, ultra low density polyethylene, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene -1-pentene copolymer, ethylene-1-octene copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, ethylene-maleic acid copolymer, styrene-ethylene graft copolymer, Styrene-propylene graft copolymer, styrene-ethylene-butadiene block copolymer, propylene and the like can be used, and these polyolefins can be used alone or in combination of two or more thereof. Among these, low density polyethylene, linear low density polyethylene, ethylene-1-butene, and the like can be suitably used.
The polyolefin resin layer may be composed of two or more layers made of different resins such as a layer made of polyethylene and a layer made of ethylene-1-butene.

Examples of the styrenic hydrocarbon constituting (a) and (b) of the sealant layer include styrene, α-methylstyrene, and various alkyl-substituted styrenes. Among them, styrene can be preferably used. Examples of the conjugated diene-based hydrocarbon include isoprene, butadiene, or those obtained by adding hydrogen to these unsaturated bonds.

A copolymer of styrene hydrocarbon and conjugated diene comprising 65% by mass to less than 90% by mass of styrene hydrocarbon and 10% by mass to less than 35% by mass of styrene hydrocarbon constituting (a) of the sealant layer is JISK. A material having a bending elastic modulus of 1000 MPa to 2500 MPa when measured at a bending speed of 2 mm by the measuring method 7171 is preferable. In particular, those having a haze of 5% or less at a thickness of 4 mm measured by JISK 7136 can be suitably used.

A block copolymer of a styrene hydrocarbon and a conjugated diene, comprising 10% by mass to less than 50% by mass of the styrene hydrocarbon constituting the sealant layer (b) and 50% by mass to less than 90% by mass of the conjugated diene hydrocarbon; Is generally called a styrene-based thermoplastic elastomer, and preferably has a tensile fracture strain measured by the method of JISK 6301 of 500% or more and 1500% or less.

Examples of the α-olefin in the (c) ethylene-α-olefin random copolymer constituting the sealant layer include propylene, 1-butene, 1-pentene, 1-hexene and the like. Among these, propylene, 1-butene and the like can be preferably used.

(D) Impact-resistant polystyrene constituting the sealant layer is composed of a styrene-based hydrocarbon polymer and a conjugated diene-based polymer, and the styrene-based hydrocarbon polymer forming the matrix includes a conjugated diene-based hydrocarbon polymer. The soft component fine particles to be dispersed can be used. Among them, those having a conjugated diene hydrocarbon content of 5% by mass to 15% by mass can be suitably used.

The compounding ratio of the resin compositions of the components (a) to (d) is such that the component (a) is 50 to 70% by mass, preferably 55 to 70% by mass, and the component (b) is 10 to 35% by mass, preferably 15 -30 mass%, component (c) is 10-35 mass%, preferably 15-30 mass%, component (d) is 5-25 mass%, preferably 5-20 mass%, and component (a) The total of styrenic hydrocarbons contained in 100% by mass of (d) is 50% by mass or more.

The total of styrenic hydrocarbons contained in 100% by mass of the components (a) to (d) constituting the sealant layer is 50% by mass or more, and the thickness of the sealant layer is 10 μm or more. In order to suppress “film breakage”, the sealant layer preferably has a higher breaking strength and higher tensile modulus. For this purpose, the total amount of styrenic hydrocarbons needs to be 50% by mass or more, preferably 60% by mass or more.

The method for producing the film is not particularly limited. For example, the components constituting the sealant layer are blended using a mixer such as a Henschel mixer, a tumbler mixer, or a mazeller, and then directly formed into a film by an extruder. Alternatively, after the blend is once kneaded and extruded with a single or biaxial extruder to obtain pellets, the pellet is further extruded with an extruder to form a film. As a method for forming a film, any method such as an inflation method, a T-die method, a casting method, or a calendar method may be used, but an inflation method or a T-die method is usually used. The resin that forms the sealant layer and the polyolefin layer that is part of the second layer are melted and kneaded using separate single-screw or twin-screw extruders, and both are laminated and integrated via a feed block or multi-manifold die. It is also possible to obtain a two-layer film consisting of a sealant layer and a polyolefin layer by extruding from a T die after conversion.

A cover film having a biaxially stretched polyethylene terephthalate layer, a polyolefin resin layer, and a sealant layer is formed by applying an anchor coating agent such as a urethane resin to the biaxially stretched polyethylene terephthalate layer, and passing the film of the sealant layer through the polyolefin resin. It can be produced by extrusion lamination. Alternatively, a biaxially stretched polyethylene terephthalate layer to which an anchor coating agent is applied and a polyolefin surface of a two-layer film in which a sealant layer and a polyolefin resin that is a part of the polyolefin resin layer are laminated and integrated are also part of the polyolefin resin layer. It can be manufactured by a method of extrusion lamination through a polyolefin resin.

A general laminator can be used as a film production machine. As a coater for applying the anchor coating agent to the biaxially stretched polyethylene terephthalate film, a commonly used one such as a roll coater, a gravure coater, a reverse roll coater, a bar coater, or a die coater can be used.

As the die of the laminator for extruding the polyolefin resin, for example, a T-die can be used. Further, a deckle for adjusting the film width may be provided.

The total thickness of the cover film can be suitably in the range of 40 to 100 μm. When the total thickness of the cover film is less than 40 μm, it is difficult to handle because the cover film is thin, and the film is easily cut when the cover film is peeled off. On the other hand, if the thickness of the entire cover film exceeds 100 μm, heat sealing may be difficult.

If necessary, further antistatic treatment can be performed. As the antistatic agent, for example, a surfactant-based antistatic agent, a polymer-type antistatic agent, a conductive agent, and the like can be applied by a roll coater using a gravure roll, a spray, or the like. Moreover, before performing antistatic treatment, it is preferable to subject the front and back surfaces of the film to corona discharge treatment or ozone treatment in order to uniformly apply these antistatic agents. In particular, a corona discharge treatment is preferable.

  In the cover film of the present invention, a film having a laminated structure such as a biaxially stretched polyethylene terephthalate layer / polyolefin resin layer / sealant layer can be suitably used. Other layers may be inserted between the layers of the cover film as long as the object of the present invention is not impaired.

The electronic component cover film of the present invention is used to prevent contamination of electronic components during storage, transportation, and mounting of chip-type electronic components, and to easily obtain practical peel strength. Excellent heat sealability, easy opening for easy removal, and transparency makes it possible to visually check the filled chip-type electronic components. “Out of film” can be reduced.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by these.
(Example 1)
As the resin composition (a) constituting the sealant layer, a styrene-butadiene block copolymer resin (manufactured by Denki Kagaku Kogyo Co., Ltd., “Denkaclearene”, styrene content 80% by mass, butadiene content 20% by mass), (b) Styrene-butadiene block copolymer resin (manufactured by JSR, “STR resin”, styrene content 40% by mass, butadiene content 60% by mass), (c) ethylene-1-butene random copolymer (manufactured by Mitsui Chemicals, Tuffmer A ”), (d) high-impact polystyrene (Toyo Styrol, Toyostyrene, styrene content 92% by mass, butadiene content 8% by mass) were blended to give the compositions shown in Table 1. The resin composition constituting the sealant layer was obtained by kneading at 200 ° C. using a single screw extruder having a diameter of 40 mm. This resin composition was melted again with a single screw extruder and extruded at a line speed of 13 m / min by an inflation method to obtain a single layer film. This film was laminated with a biaxially stretched polyethylene terephthalate film (thickness: 16 μm) via a polyethylene resin by an extrusion laminating method to obtain a cover film for a carrier tape of an electronic component.

(Examples 2 to 6)
As the resin composition (a) constituting the sealant layer, a styrene-butadiene block copolymer resin (manufactured by Denki Kagaku Kogyo Co., Ltd., “Denkaclearene”, styrene content 80% by mass, butadiene content 20% by mass), (b) Styrene-butadiene block copolymer resin (manufactured by JSR, “STR resin”, styrene content 40% by mass, butadiene content 60% by mass), (c) ethylene-1-butene random copolymer (manufactured by Mitsui Chemicals, Tuffmer A ”), (d) high-impact polystyrene (Toyo Styrol, Toyostyrene, styrene content 92% by mass, butadiene content 8% by mass) were blended to give the compositions shown in Table 1. Using a single screw extruder having a diameter of 40 mm, the mixture was kneaded at 200 ° C. to obtain a resin composition constituting the sealant layer at a line speed of 20 m / min. This resin composition and low density polyethylene as a polyolefin resin were extruded from separate single screw extruders and laminated with a multi-manifold die to obtain a two-layer film. This two-layer film was laminated with a biaxially stretched polyethylene terephthalate film (thickness: 16 μm) through a polyethylene resin by an extrusion laminating method to obtain a cover film for a carrier tape of an electronic component.

(Comparative Examples 1-8)
In the same manner as in Examples 2 to 7, components (a) to (d) were blended so as to have the compositions shown in Table 2 to obtain a resin composition constituting the sealant layer. Next, this resin composition and low-density polyethylene as a polyolefin resin were extruded from separate single-screw extruders and laminated with a multi-manifold die to obtain a two-layer film. This two-layer film was laminated with a biaxially stretched polyethylene terephthalate film (thickness: 16 μm) through a polyethylene resin by an extrusion laminating method to obtain a cover film for a carrier tape of an electronic component.

(Comparative Example 9)
In the same manner as in Example 1, the components (a) to (d) were blended so as to have the compositions shown in Table 2 to obtain a resin composition constituting the sealant layer. This resin composition was melted again with a single-screw extruder, and a single-layer film was formed by extrusion at a line speed of 13 m / min by the inflation method. However, when the formed film was wound up, it was blocked. The subsequent evaluation was difficult.

The following evaluations were performed on the carrier tape cover films for electronic components prepared in the above Examples and Comparative Examples. These results are summarized in Tables 1 and 2.
(1) Haze value The haze value was measured using an integrating sphere measuring device according to measurement method A according to JIS K 7105: 1998.
(2) Heat sealability Using a taping machine (Systemation, ST-60), seal head width 0.5 mm × 2, seal head length 32 mm, seal pressure 3.5 MPa, feed length 16 mm, seal time 0.5 A cover film with a width of 21.5 mm was sealed on a carrier tape with a width of 24 mm at a seal head temperature of 150 ° C. or 160 ° C. in seconds × 2 (double seal). After leaving for 24 hours, the cover film is peeled off at a speed of 300 mm / min and a peeling angle of 180 °, and those having an average peel strength in the range of 0.2 to 0.6 N are defined as “good”. Was marked as “bad”. In addition, those that could not be evaluated for heat sealability due to difficulty in film formation were described as “impossible”. The results are shown in the heat sealability column of Tables 1 and 2.
(3) Film cutting property Using a taping machine (Systemation, ST-60), seal head width 0.5 mm × 2, seal head length 32 mm, seal pressure 3.5 MPa, feed length 16 mm, seal time 0.5 Seal 21.5mm wide cover film to 24mm wide electronic component carrier tape so that average peel strength is 1N and 1.5N by adjusting seal head temperature in seconds x 2 (double seal) did. The carrier tape with the cover film sealed was cut out to a length of 550 mm, and the pocket bottom of the carrier tape was attached to a vertical wall on which a double-sided adhesive tape was attached. The cover film was peeled off by 50 mm from the upper part of the affixed carrier tape, the cover film was sandwiched between clips, and a weight having a mass of 1000 g was attached to the clip. After that, when the weight was naturally dropped, the cover tape did not break even when the peel strength was 1.5 N, “excellent”, and the cover film was not broken when the peel strength was 1.0 N, “good” Those in which breakage was observed even at a peel strength of 1.0 N were indicated as “bad”. In addition, those that could not be evaluated for film breakability due to difficulty in film formation were described as “impossible”. The results are shown in the film breakability column of Tables 1 and 2.
(4) Film-forming properties Films were formed by the methods of Examples and Comparative Examples, and those with a film thickness variation of ± 20% or less were evaluated as “good”, and those exceeding ± 20% were determined as “bad”. Indicated. Moreover, when the film formed was wound up, what caused the “blocking phenomenon” in which the front and back surfaces of the film adhered and could not be peeled off was also described as “bad”. The results are shown in the column of film formability in Tables 1 and 2.

Figure 1 shows the film breakability test method

Explanation of symbols

1. Wall 2. 2. Double-sided adhesive tape Carrier tape4. 4. Cover film Clip 6. String 7. weight

The cover film provided by the present invention is excellent in heat sealability for easily obtaining a practical peel strength and transparency capable of visually recognizing electronic components, and more likely to occur during high-speed peeling. The “film break” of the film can be reduced.

The cover film of the present invention can be applied to various small electric parts in addition to electronic parts.

Claims (3)

It has a biaxially stretched polyethylene terephthalate layer, a polyolefin resin layer, and a sealant layer, the sealant layer has a thickness of 10 μm or more, and consists of the following components (a) to (d), and the sum of (a) to (d) The cover film whose sum total of the styrene-type hydrocarbon contained in 100 mass% is 50 mass% or more.
(A) Copolymer of styrene hydrocarbon and conjugated diene comprising 65% by mass or more and less than 90% by mass of styrene hydrocarbon and 10% by mass or more and less than 35% by mass of conjugated diene hydrocarbon: 52 to 70% by mass
(B) Styrenic hydrocarbon and conjugated diene block copolymer comprising 10% by mass or more and less than 50% by mass of styrene hydrocarbon and 50% by mass or more and less than 90% by mass of conjugated diene hydrocarbon: 10 to 30 % by mass
(C) Ethylene-α-olefin random copolymer: 10 to 32 % by mass
(D) Impact-resistant polystyrene: 5 to 25% by mass The cover film according to claim 1, wherein at least one side is subjected to antistatic treatment. An electronic component packaging container using the cover film according to claim 1.

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