JP2018089846A - Transparent Conductive Cover Tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent conductive cover tape which has sufficient seal strength and stable easy-peelability, holds high transparency, and exhibits excellent antistatic properties applicable to packaging of an electronic component.SOLUTION: A transparent conductive cover tape is formed by laminating a base material film 1, an adhesive layer 2, a first intermediate layer 3a, a second intermediate layer 3b and a heat seal layer 4 in this order, where the first intermediate layer 3a is a layer formed of a polyethylene-based resin, the second intermediate layer 3b is a layer formed from a resin composition containing an ethylene-α-olefin copolymer and a styrene-butadiene block copolymer, the first intermediate layer 3a and the second intermediate layer 3b are layers formed by a coextrusion method, the heat seal layer 4 is a layer formed of a transparent conductive heat seal material formed by dispersing conductive fine particles in an acrylic resin, and the conductive fine particles are barium sulfate particles or silicon dioxide particles obtained by coating their surfaces with tin oxide doped with antimony.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a transparent conductive cover tape. More specifically, the present invention relates to a transparent conductive cover tape that is used as a cover material that covers an opening of a pocket with respect to a carrier tape provided with a pocket that accommodates an electronic component such as a semiconductor element.

  In recent years, electronic parts such as IC chips and capacitors have been taped and used for surface mounting on electronic circuit boards. Taping packaging is a packaging form in which a pocket portion is formed continuously by embossing, and an electronic component is accommodated in each pocket portion, and the opening of the pocket is covered with a cover tape and heat sealed. .

  If static electricity is generated when the cover tape is peeled off from the carrier tape, the internal electronic components are deteriorated or electrostatically damaged. Therefore, the carrier tape and the cover tape are required to have high antistatic properties.

  Further, in order to detect a defect in the product or to recognize a code or the like printed on the product, a camera inspection is performed on the cover tape while the taping package is unopened. For this reason, the cover tape is also required to have high transparency.

  Furthermore, the taping package containing electronic parts is kept sealed during transportation and storage, and zip-up (peeling with the progress of peeling) so that the cover tape can be peeled stably and smoothly when electronic parts are mounted. The difference between the maximum value and the minimum value is required to be small.

  If the zip-up is large, the carrier tape vibrates when the cover tape is peeled off, causing a problem that the electronic component stored in the pocket portion pops out or cannot be loaded at a desired position.

  In response to these requirements, a transparent conductive cover tape with stable and easy peelability is a cover tape formed by kneading or applying a metal oxide fine particle or other anti-conductive material into a heat seal layer that is in direct contact with an electronic component. Is known (for example, Patent Document 1).

  However, in order to obtain the antistatic properties required as a packaging body for electronic parts, it is necessary to use a large amount of an antistatic material, which reduces transparency and makes it difficult to confirm the inside by camera inspection. There is a problem.

  In addition, there is a problem that a desired seal strength cannot be obtained when heat-sealing on a carrier tape. This is particularly serious in a carrier tape made of polystyrene or polycarbonate that has been widely used in recent years, and a problem is known that the cover tape peels off during transportation and storage of the taping package, and the internal electronic components fall off. .

  On the other hand, if the addition amount of the antistatic material is reduced in order to ensure transparency and sealing strength, sufficient antistatic performance cannot be exhibited and generation of static electricity cannot be prevented.

Japanese Patent Laid-Open No. 7-251860

  The present invention solves the above-mentioned problems and exhibits excellent antistatic properties applicable to packaging of electronic components while maintaining sufficient transparency with sufficient seal strength and stable peelability. An object of the present invention is to provide a transparent conductive cover tape.

  As a result of various studies, the inventor has obtained a first intermediate layer made of a polyethylene resin and a second intermediate layer made of a blend resin of an ethylene / α-olefin copolymer and a styrene / butadiene block copolymer. A film is formed by coextrusion, and a resin composition in which conductive fine particles are dispersed in an acrylic resin is laminated on the second intermediate layer as a heat seal layer. Here, antimony is used as the conductive fine particles. It has been found that the above object can be achieved by using barium sulfate particles or silicon dioxide particles coated with tin oxide doped with.

That is, the present invention is characterized by the following points.
(1) A transparent conductive cover tape that can be heat-sealed to a carrier tape, which is formed by sequentially laminating a base film, an adhesive layer, a first intermediate layer, a second intermediate layer, and a heat seal layer. The first intermediate layer is a layer made of a polyethylene resin, and the second intermediate layer is a layer made of a resin composition containing an ethylene / α-olefin copolymer and a styrene / butadiene block copolymer. The first intermediate layer and the second intermediate layer are layers formed by a coextrusion method, and the heat seal layer is a transparent material in which conductive fine particles are dispersed in an acrylic resin. The transparent conductive cover tape, comprising a conductive heat seal material, wherein the conductive fine particles are barium sulfate particles or silicon dioxide particles coated with tin oxide doped with antimony.
(2) The transparent conductive cover tape according to (1), wherein the polyethylene-based resin forming the first intermediate layer is linear low density polyethylene (LLDPE).
(3) The second intermediate layer is a layer composed of a resin composition containing 30 to 70% by mass of an ethylene / α-olefin copolymer and 70 to 30% by mass of a styrene / butadiene block copolymer. The transparent conductive cover tape according to the above (1) or (2).
(4) The said acrylic resin is a transparent conductive cover tape in any one of said (1)-(3) whose glass transition temperature is 20-100 degreeC.
(5) The transparent conductive cover tape according to any one of (1) to (4), wherein the total light transmittance is 70% or more and the haze is 30% or less.

  The present invention has been found that the surface resistivity of a film is greatly reduced by laminating layers composed of a combination of a specific resin and a conductive prevention material in a specific order and method.

  Therefore, the transparent conductive cover tape of the present invention can provide a high anti-electroconductive effect with a small amount of anti-conductive material, and at the same time, can maintain high transparency and good seal strength.

  In addition, since the intermediate layer formed by co-extrusion of the two layers guarantees the sealing strength and contributes to easy peelability, even if a heat seal layer is provided thinly, high sealing performance is achieved and smooth zip-up is smooth. A feeling of opening is obtained.

  In particular, the transparent conductive cover tape of the present invention can be suitably used for a carrier tape made of polystyrene or polycarbonate, and exhibits the above effects.

It is a schematic sectional drawing which shows the transparent conductive cover tape of this invention. It is a schematic sectional drawing which shows an example of the state heat-sealed with the carrier tape using the transparent conductive cover tape of this invention as a cover material.

  The present invention will be described in more detail below.

<1> Layer Configuration of Transparent Conductive Cover Tape of the Present Invention FIG. 1 is a schematic cross-sectional view showing the transparent conductive cover tape of the present invention.

  FIG. 2 is a schematic cross-sectional view showing an example of a state in which the transparent conductive cover tape of the present invention is heat sealed with a carrier tape.

  As shown in FIG. 1, the transparent conductive cover tape of the present invention is obtained by laminating an intermediate layer 3 on a base film 1 via an adhesive layer 2 and laminating a heat seal layer 4 thereon. It is. Here, the intermediate layer 3 is made of a coextruded film obtained by forming a first intermediate layer 3a and a second intermediate layer 3b together by a coextrusion method.

  The film formation by the co-extrusion method is performed by extruding a plurality of melted resins from a plurality of thin slit-like gaps, unlike a lamination method in which simple single films are bonded together.

  Therefore, the interface between the layers formed by coextrusion exhibits a very unique structure, which is greatly different from the interlayer structure due to entanglement interaction such as self-adhesion by the laminate manufacturing method.

  Specifically, the interface formed by coextrusion is considered to form an interlocking structure in which the crystals of each resin enter each other, and has an extremely complicated structure.

  Therefore, in the present invention, there is only a method for specifying an intermediate layer that can be expressed as a layer formed by a coextrusion method, that is, the characteristics of the present invention can be expressed only by specifying a product by a manufacturing method. .

  When the transparent conductive cover tape of the present invention is applied as a cover material for a carrier tape, the cover tape of the present invention is overlaid on the pocket portion 6 of the carrier tape 5 so that the surface of the heat seal layer 4 faces. Heat seal.

<2> Base Film In the present invention, the base film is a uniaxial film made of a polyester such as polyethylene terephthalate (PET) or polyethylene naphthalate, a polyolefin such as polypropylene, a polyamide such as nylon, or a thermoplastic resin such as polycarbonate. Or the film formed by extending | stretching to a biaxial direction can be used.

  These may be used alone, or two or more films of the same type or different types may be laminated by any lamination means.

  In view of transparency, heat resistance and moisture resistance suitable for the cover tape, a PET film can be particularly preferably used.

  If necessary, surface treatment such as corona discharge treatment, plasma treatment, sandblast treatment, etc. can be applied in advance to the surface in contact with the adhesive layer in order to strengthen the adhesive strength with the adhesive layer. .

  In addition, if necessary, the surface opposite to the side that contacts the adhesive layer, that is, the outermost surface, can be used to prevent dust and dirt from adhering to the surface and to prevent static electricity from coming into contact with other surfaces. In addition, an antistatic treatment may be performed using a surfactant, an ionic liquid, a conductive polymer, conductive carbon black, metal deposition, conductive fine particles such as a metal oxide, and the like.

  The thickness of the base film can be appropriately set by those skilled in the art, and is, for example, 3 to 25 μm for the purpose of imparting appropriate strength and waist to the cover tape.

<3> Adhesive layer An intermediate layer is bonded to one surface of the base film via the adhesive layer. Here, any adhesive for dry lamination can be used as the adhesive.

  Adhesives for dry laminating include one- or two-component curable vinyl, (meth) acrylic, polyamide, polyester, polyether, polyurethane, epoxy, rubber and other solvent types, and water-based types Or an adhesive for laminating such as an emulsion type can be used. Further, the application of the adhesive may be gravure coating, roll coating, or the like, and the method thereof is not questioned.

Although the thickness of an adhesive bond layer can be adjusted suitably, for example, it is 1-10 g / m < ² >, Preferably it is 2-5 g / m < ² > so that moderate rigidity may be given to a cover tape. If it is thinner than 1 g / m ² , the adhesive strength cannot be made uniform, and the rigidity necessary for stabilizing the zip-up can be reduced.

On the other hand, if it is thicker than 10 g / m ² , not only is it disadvantageous in price, but the rigidity becomes too strong and the cover tape may be cracked.

<4> Intermediate layer In the present invention, the intermediate layer is a layer located between the base film and the heat seal layer, and the first intermediate layer and the second intermediate layer are formed by coextrusion. It consists of a film made of.

  The first intermediate layer is a layer located on the base film side. This layer imparts cushioning properties to the cover tape, ensures sealing strength with the carrier tape, and at the same time achieves high interlayer adhesion strength with the base film via the adhesive layer.

  Furthermore, it is also a layer that plays a role of backing and supporting the second intermediate layer and enhances film formation stability during coextrusion film formation.

  In the present invention, the first intermediate layer is made of a polyethylene resin. Here, as the polyethylene resin, linear (linear) low density polyethylene, high pressure method low density polyethylene, medium density polyethylene, high density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-acrylic Acrylic acid such as ethyl acid copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-propylene copolymer, methylpentene polymer, polyethylene, polyethylene resin or polypropylene resin , An acid-modified polyolefin resin modified with an unsaturated carboxylic acid such as methacrylic acid, maleic anhydride, or fumaric acid, or a mixture of two or more of these.

  It is particularly preferable to use linear low-density polyethylene in order to ensure the sealing strength and sufficiently exhibit the functions of improving the film-forming stability and to give the cover tape good flexibility and transparency.

  In the present invention, the linear low-density polyethylene is a low-temperature, low-pressure ethylene and α-olefin having 3 to 20 carbon atoms using a single site catalyst such as a metallocene catalyst or a multisite catalyst such as a Ziegler-Natta catalyst. It is a copolymer obtained by copolymerization with

  Specific examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene and 1-decene. , 1-dodecene and the like. Examples of the copolymerization method include ethylene and α-olefin polymerization methods such as a low pressure method, a slurry method, a solution method, and a gas phase method.

  The second intermediate layer is a layer located on the heat seal layer side. This layer exhibits stable interlayer adhesion strength with the heat seal layer, and contributes to both sealing performance and easy peelability.

  In the present invention, the second intermediate layer is made of a resin composition containing an ethylene / α-olefin copolymer and a styrene / butadiene block copolymer.

  Here, as the ethylene / α-olefin copolymer, the linear low-density polyethylene mentioned for the first intermediate layer can be used.

  By using the linear low-density polyethylene, the transparency is improved, and the peel strength can be easily controlled according to the blend ratio with polystyrene.

  Examples of the styrene monomer constituting the styrene / butadiene block copolymer include styrene, chlorostyrene, chloromethylstyrene, t-butylstyrene, vinyltoluene and the like.

  In addition to butadiene, the monomer copolymerizable with these may include isoprene, acrylonitrile, methacrylonitrile, and the like.

  In addition to styrene / butadiene block copolymer, polystyrene, high impact polystyrene, styrene / butadiene graft copolymer, block or graft copolymer of styrene and isoprene, acrylonitrile / butadiene / styrene copolymer, or these Two or more mixtures may be included.

  In particular, a styrene / butadiene block copolymer obtained by copolymerizing 50 to 90% by mass of styrene and 50 to 10% by mass of butadiene is preferably used.

  In the resin composition, when the ratio of the polystyrene-based resin and the styrene-derived unit is too large, the transparency is lowered, but the adhesion between layers is increased and the easy peelability tends to be lowered. Moreover, when it coextrudes with a 1st intermediate | middle layer, there exists a tendency for film forming property to fall.

  The resin composition forming the second intermediate layer controls the interlayer adhesion strength with the heat seal layer by adjusting the blend ratio of the ethylene / α-olefin copolymer and the styrene / butadiene block copolymer. The desired easy peelability and sealability can be achieved at the same time.

  Here, the blend ratio of the two can be appropriately adjusted by those skilled in the art according to the content of the styrene-derived unit in the styrene / butadiene block copolymer to be used and the desired seal strength (peel strength). it can.

  In order to obtain suitable sealing strength and easy-openability as a cover tape from the balance between the first intermediate layer and the heat seal layer described later, the second intermediate layer is 70 to 110 ° C, more preferably 82 ° C or higher. For example, it preferably has a Vicat softening point of 82 to 85 ° C.

  In order to obtain such a second intermediate layer, the resin composition forming the second intermediate layer is, for example, an ethylene / α-olefin copolymer of 30 to 70% by mass and a styrene / butadiene block copolymer. It is blended with 70 to 30% by mass.

  The blend ratio of the two is more preferably 50-30% by mass of styrene / butadiene block copolymer with respect to 50-70% by mass of ethylene / α-olefin copolymer, and more preferably ethylene / α-olefin. The styrene / butadiene block copolymer is 45 to 30% by mass with respect to 55 to 70% by mass of the copolymer, and the total of both is 100% by mass.

  If the above range is exceeded and the styrene content is low and the Vicat softening point is too high, the flexibility of the layer is insufficient, and the sealing property and adhesion between layers are impaired. On the other hand, if the styrene content is high and the Vicat softening point is too low, the zip-up increases and the easy peelability is impaired.

  In the present invention, the Vicat softening point is a value measured based on the A120 method of JISK7206.

  The sum total of the thickness of a 1st and 2nd intermediate | middle layer is 15-50 micrometers, More preferably, it is 20-45 micrometers. If the thickness of the entire intermediate layer is too thin, sufficient cushioning properties are not exhibited and the sealing strength is not ensured.

  Moreover, film formation becomes unstable and a uniform film cannot be formed. On the other hand, if it is too thick, the sealing strength is not ensured unless the sealing temperature is increased and the sealing time is lengthened.

  The thickness of the second intermediate layer is 2 to 20 μm, more preferably 5 to 15 μm. If the second intermediate layer is too thin, the sealing strength is lowered, which is not preferable. On the other hand, if it is too thick, wrinkles, uneven thickness, and pinholes are liable to occur during the formation of the intermediate layer.

  The film forming the first and second intermediate layers is formed by coextrusion of two layers by a conventional film forming method such as an inflation method or a T-die method.

  The film formation by the co-extrusion method is performed by extruding a plurality of melted resins from a plurality of thin slit-like gaps, unlike a lamination method in which simple single films are bonded together.

  If necessary, the surface of the film may be subjected to surface treatment such as corona discharge treatment, plasma treatment, and sandblast treatment in order to increase the adhesive strength between the adhesive layer and the heat seal layer.

  Moreover, the 1st and 2nd intermediate | middle layer may contain arbitrary additives as needed in the range which does not inhibit the effect of invention.

  As such an additive, the various resin additives generally used in order to adjust the moldability of a resin film, productivity, and various physical properties can be used. However, particles such as conductive fine particles are not included because of effects on transparency, interlayer adhesion, easy peelability, and the like.

<5> Heat Seal Layer In the present invention, the heat seal layer is made of a transparent conductive heat seal material in which conductive fine particles are dispersed in an acrylic resin.

  The transparent conductive heat sealing material preferably has a glass transition point of 20 to 100 ° C., more preferably 30 to 60 ° C. from the viewpoint of easy peelability, heat sealing properties and blocking properties. When the glass transition point is too low, the heat seal layer becomes soft, and the coating film formability and easy peelability are impaired. Conversely, if the glass transition point is too high, the heat seal layer becomes hard and sufficient seal strength cannot be obtained.

  In the present invention, the glass transition point is a value measured in accordance with JISK7121.

  In the present invention, the acrylic resin includes homopolymers and copolymers of acrylic monomers. Examples of the acrylic monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and the like. However, (meth) acrylate refers to acrylate or methacrylate.

  Examples of monomers copolymerizable with these include styrene monomers such as styrene, chlorostyrene, chloromethylstyrene, t-butylstyrene, vinyltoluene and the like.

  Specifically, polymethyl (meth) acrylate, polyethyl (meth) acrylate, polybutyl (meth) acrylate, methyl (meth) acrylate-butyl (meth) acrylate copolymer, random (block) of methyl (meth) acrylate and styrene Alternatively, a graft copolymer, a random, block or graft copolymer of ethyl (meth) acrylate and styrene may be used. From the viewpoint of coating film formability and the like, a copolymer with styrene can be particularly preferably used.

  The styrene content in the copolymer of acrylate and styrene can be appropriately determined by those skilled in the art depending on the resin forming the second intermediate layer and the desired easy peelability. For example, the styrene content is It is 0-30 mass%, More preferably, it is 0-20 mass%.

  If the styrene content is too high, the glass transition point is lowered, and the film-forming property and the easy peelability can be impaired. Conversely, when the styrene content is low, it may be difficult to form a uniform coating film.

  By using these acrylic resins as the binder of the heat seal material, not only the desired heat sealability and easy peelability can be achieved, but also, for example, when using a particularly preferred PET film as the base film, Generation of blocking can be prevented.

  In the present invention, the conductive fine particles dispersed in the acrylic resin are barium sulfate particles or silicon dioxide particles coated with antimony-doped tin oxide on the surface.

  Antimony-doped tin oxide is obtained by substituting oxygen atoms on the tin oxide molecule with antimony atoms by an ion doping method.

  Fine particles obtained by coating the antimony-doped tin oxide on barium sulfate particles or silicon dioxide particles so that the volume resistivity is 500 Ω · m or less, preferably 100 Ω · m or less can be suitably used in the present invention. it can.

  By using antimony-doped tin oxide coated on the fine particles, an inexpensive and uniform fine powder can be obtained. In particular, when coated on barium sulfate particles having a refractive index of about 1.6 or silicon dioxide particles having a refractive index of about 1.5, the average particle size of the core particles is 0.3 μm or less. Preferably, by setting the particle size to 0.2 μm or less, and further to 0.1 μm or less, the particles do not diffuse visible light, so that high transparency can be secured.

  In the present invention, the average particle diameter is a 50% particle diameter (d50 median diameter) when the particle diameter distribution measured by the laser diffraction scattering method is represented by a volume cumulative distribution.

  As the conductive fine particles, barium sulfate particles or silicon dioxide particles coated with antimony-doped tin oxide are used and dispersed in an acrylic resin, thereby achieving high antistatic properties with a small amount of conductive fine particles. . Therefore, the heat seal layer can be set thin, and the transparency is not impaired.

  Furthermore, when heat-sealed with a polystyrene or polycarbonate carrier tape, combined with the action of the first and second intermediate layers, it achieves good seal strength and peel strength, and has excellent sealing properties and ease. It is possible to achieve both releasability.

  The mass ratio of the acrylic resin to the conductive fine particles is 10 to 400 parts by mass of the conductive fine particles with respect to 100 parts by mass of the acrylic resin.

  When the amount of the conductive fine particles is larger than the above range, the transparency of the coating film is deteriorated, which is not preferable. On the other hand, if the amount of the conductive fine particles is less than the above range, the necessary antistatic performance cannot be obtained, which is not preferable.

  The thickness of the heat seal layer is from 0.1 to 5 μm, and particularly preferably from 0.2 to 2 μm, from the viewpoints of transparency, sealing properties and antistatic effects. In the present invention, the heat seal layer is composed of a combination of the acrylic resin and barium sulfate particles or silicon dioxide particles coated with antimony-doped tin oxide, so that a sufficient antistatic effect can be obtained even if the layer thickness is reduced. can get.

In the present invention, the heat seal layer has a surface resistivity of 10 ⁵ to 10 ¹² Ω / □ under 22 ° C. and 40% RH. Further, at 23 ± 5 ° C. and 12 ± 3% RH, the charge decay time required to decay from 5000 V to 99% is 1 second or less, and it has excellent electrostatic characteristics.

If the surface resistivity exceeds 10 ¹² Ω / □, the electrostatic diffusion effect becomes extremely poor, and it becomes difficult to protect electronic components from electrostatic breakdown. If the surface resistivity is less than 10 ⁵ Ω / □, Therefore, there is a possibility that electricity flows through the electronic component through the lid member, and there is a risk that the electronic component is electrically destroyed.

    On the other hand, if the charge decay time, which is a measure of the diffusion rate of charges generated by static electricity, exceeds 1 second, the electrostatic diffusion effect is extremely deteriorated, and it is difficult to protect electronic components from electrostatic breakdown.

  The surface resistivity and the charge decay time can be measured according to MIL-B-81705C, which is an American military standard.

  The heat seal layer may contain additives such as a dispersion stabilizer, a surfactant, and an antiblocking agent as necessary.

  The heat seal layer is formed on the second intermediate layer by a gravure coating method, an air doctor coating method, a blade coating method, a knife coating method, a rod coating method, a direct roll coating method, a reverse roll coating method, a slide coating method, a slot coating method. It can be formed by a coating method such as a refill coating method.

<6> Conductive Cover Tape The cover tape of the present invention as described above has transparency such that the total light transmittance is 70% or more and the haze value is 30% or less. More preferably, the total light transmittance is 75% or more and the haze value is 25% or less, and particularly preferably, the total light transmittance is 80% or more and the haze value is 23% or less.

  Therefore, the taping package using the cover tape of the present invention can inspect and confirm the presence / absence of the contents and the filling state by visual inspection or camera inspection in an unopened state from above the cover tape.

  When the cover tape of the present invention is opened from the carrier tape, peeling occurs between the second intermediate layer and the heat seal layer in the seal portion (delamination), and heat between the heat seal layer and the carrier tape is generated. It has stable peeling performance regardless of the fusing conditions. This peel strength (interlayer adhesive strength) is weaker than the peel strength between the heat seal layer and the carrier tape, and is preferably in the range of 100 to 1200 gf / 15 mm.

  When the peel strength is less than 100 gf / 15 mm, there is a risk that peeling occurs during transportation and storage of the package, and the contents fall off. On the other hand, if the peel strength exceeds 1200 gf / 15 mm, the carrier tape may vibrate and the contents may pop out when the cover tape is peeled off.

  In the present invention, the peel strength is a value of 180 degree peeling (peeling speed 300 mm / min) in an atmosphere of 23 ° C. and relative humidity 40%.

  Further, the zip-up is preferably 30 gf / 1 mm or less. If the zip-up exceeds 50 gf / 1 mm, the carrier tape may vibrate when the cover tape is peeled off, and the contents may jump out, which is not preferable.

  The zip-up here refers to the maximum and minimum peel strength when the cover tape and carrier tape are heat sealed using two 0.5 mm wide heat seal bars and then peeled off. And the difference.

  The zip-up measurement conditions are numerical values when the measurement length of 20 mm is peeled 180 degrees under the condition of a peeling speed of 300 mm / min in an atmosphere of 23 ° C. and relative humidity of 40%.

  The material of the carrier tape to which the cover tape of the present invention is applied is polyvinyl chloride, polystyrene, polyester, polypropylene, polycarbonate, polyacrylonitrile, ABS, etc., particularly preferably polystyrene and polycarbonate.

  In addition, as an antistatic measure, conductive carbon black fine particles, metal fine particles, conductive fine particles obtained by imparting conductivity to metal oxides, organosilicon compounds, or surfactants are kneaded into these resins or contain these. May be applied.

  Next, the present invention will be specifically described with reference to examples.

[Example 1]
A first intermediate layer (thickness 20 μm) made of linear low-density polyethylene having a density of 0.925 (Evolue SP2520 manufactured by Prime Polymer Co., Ltd.) and linear low-density polyethylene having a density of 0.919 (Prime Co., Ltd.) Resin composition (Vicat softening point 85 ° C.) comprising 60% by mass of polymer Ultrazex 2021L) and 40% by weight of styrene / butadiene block copolymer (Asaflex 810 manufactured by Asahi Kasei Chemicals Corporation, styrene content 65% by mass) And a second intermediate layer (thickness 10 μm) formed by coextrusion to obtain a film having a total thickness of 30 μm.

  The surface of the first intermediate layer of this film and the corona-treated surface of a 12 μm-thick biaxially stretched PET film (E7415 single-side antistatic / single-sided corona-treated type manufactured by Toyobo Co., Ltd.) are formed from a polyol and a curing agent. Dry lamination was performed through the adhesive layer.

  Next, the surface of the second intermediate layer of the obtained laminate was coated with conductive fine particles (antimony-doped tin oxide) in 100 parts by mass of an acrylic resin (copolymer such as methyl methacrylate). A transparent conductive heat seal material (glass transition point 50 ° C.) obtained by dispersing 240 parts by mass of barium sulfate particles (average particle size 0.25 μm) is applied by a roll coating method to a thickness of 2 μm, and the cover tape of the present invention is applied. Manufactured.

  About the obtained cover tape, surface resistivity, charge decay time, haze value, total light transmittance, peel strength, and zip-up were measured under the following conditions.

(Surface resistivity)
The measurement was performed with Hiresta UP manufactured by Mitsubishi Chemical Analytech Co., Ltd. at 22 ° C. and 40% RH.

(Charge decay time)
STATIC DECAY METER manufactured by ETS (Electro-Tech Systems, Inc.) based on MIL-B-81705C, the time required for attenuation from 5000 V to 99% at 23 ± 5 ° C. and 12 ± 3% RH Measured at -406C.

(Haze value and total light transmittance)
Measured with Hazeguard II manufactured by Toyo Seiki Seisakusho.

(Peel strength)
The obtained cover tape was heat-sealed on a polystyrene base material at 150 ° C. for 0.5 seconds and 3.0 kgf / cm ² , and then manufactured by Toyo Baldwin Co., Ltd. at 23 ° C. and 40% RH. The peel strength was measured with a Tensilon universal testing machine HTH-100. (Peeling speed = 300 mm / min, 180 ° peeling)

(Zip up)
The obtained cover tape was heat-sealed on a polystyrene carrier tape using two 0.5 mm-wide heat seal bars under the conditions of 150 ° C., 0.4 seconds, and 3.0 kgf, and then 23 ° C. Under 40% RH, peel strength was measured with a peel strength tester VG-20 manufactured by Vanguard Systems Co., Ltd. (peel rate = 300 mm / min, measured length 20 mm, 180 ° peel), and maximum and minimum values The difference was obtained.

  The measurement results are shown in Table 1 below.

  The cover tape of the present invention manufactured in the examples has a suitable surface resistivity and a sufficiently short charge decay time, so it has excellent electrostatic characteristics and protects electronic components from electrostatic breakdown and the like. can do. Moreover, it has high transparency, and the state of the contents can be easily confirmed by camera inspection.

  Furthermore, it has good peel strength and maintains easy-openability while sufficiently sealing the contents. In particular, the peel strength zip-up is small, and a very smooth peel feeling can be obtained.

[Example 2]
A cover tape of the present invention was produced in the same manner as in Example 1 except that silicon dioxide particles were used instead of barium sulfate particles as the core material for the conductive fine particles. The obtained cover tape exhibited the same properties as the cover tape of Example 1.

[Example 3]
In the same manner as in Example 1, except that a resin composition containing 80% by mass of linear low density polyethylene and 20% by weight of styrene / butadiene block copolymer was used as the second intermediate layer. A cover tape was produced. The obtained cover tape exhibited suitable surface resistivity and electrostatic characteristics, but had low peel strength and slightly poor sealability.

[Comparative Example 1]
As in Example 1, except that antimony-free tin oxide powder was used as the conductive fine particles, and a heat seal material in which 240 parts by mass of the tin oxide powder was dispersed in 100 parts by mass of the acrylic resin was used. A cover tape was manufactured.

  The obtained cover tape had a higher surface resistivity, a longer charge decay time, and an inferior electrostatic diffusion effect compared to the cover tape of the example.

[Comparative Example 2]
A cover tape was produced in the same manner as in Example 1 except that a 30 μm-thick polyethylene film was used instead of the coextruded film composed of the first and second intermediate layers. The obtained cover tape had a lower interlayer adhesive strength between the heat seal layer and the intermediate layer than the cover tape of the example, and was inferior in sealing performance.

1. 1. Base film 2. Adhesive layer Intermediate layer 3a. First intermediate layer 3b. Second intermediate layer 4. 4. Heat seal layer Carrier tape6. Pocket part

Claims (5)

A transparent conductive cover tape for heat sealing against a carrier tape,
A base film, an adhesive layer, a first intermediate layer, a second intermediate layer, and a heat seal layer are sequentially laminated,
The first intermediate layer is a layer made of a polyethylene resin, and the second intermediate layer is a layer made of a resin composition containing an ethylene / α-olefin copolymer and a styrene / butadiene block copolymer. The first intermediate layer and the second intermediate layer are layers formed by coextrusion,
The heat seal layer is a layer made of a transparent conductive heat seal material in which conductive fine particles are dispersed in an acrylic resin, and the conductive fine particles are sulfuric acid coated with antimony-doped tin oxide on the surface. The transparent conductive cover tape described above, which is silicon dioxide particles whose surface is coated with barium particles or tin oxide doped with antimony.   The transparent conductive cover tape according to claim 1, wherein the polyethylene-based resin forming the first intermediate layer is linear low-density polyethylene.   The second intermediate layer is a layer made of a resin composition containing 30 to 70% by mass of an ethylene / α-olefin copolymer and 70 to 30% by mass of a styrene / butadiene block copolymer. Or the transparent conductive cover tape of 2.   The transparent conductive cover tape according to any one of claims 1 to 3, wherein the acrylic resin has a glass transition temperature of 20 to 100 ° C.   The transparent conductive cover tape of any one of Claims 1-4 whose total light transmittance is 70% or more, and a haze is 30% or less.