JP7028016B2 - Transparent conductive cover tape - Google Patents

Description

The present invention relates to a transparent conductive cover tape.

More specifically, the present invention relates to a transparent conductive cover tape used as a lid material for covering an opening of the pocket with respect to a carrier tape provided with a pocket for accommodating an electronic component such as a semiconductor element.

In recent years, electronic components such as IC chips and capacitors are taped and packaged and used for surface mounting on electronic circuit boards. Taping packaging is a packaging form in which electronic components are stored in each pocket portion, the opening of the pocket is covered with a cover tape, and the pocket portion is heat-sealed in a carrier tape in which the pocket portion is continuously formed by embossing. ..

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

In addition, in order to detect defects in the product and recognize the code printed on the product, the taping package is unopened and a camera inspection is performed on the cover tape. Therefore, the cover tape is also required to have high transparency.

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

If the zip-up is large, the carrier tape vibrates when the cover tape is peeled off, causing problems that the electronic components housed in the pocket portion pop out or cannot be loaded in a desired position.

To meet these demands, as a transparent conductive cover tape with stable and easy peeling properties, a cover tape made by kneading or applying a conductive material such as metal oxide fine particles into a heat seal layer that comes into direct contact with electronic components. Is known (for example, Patent Document 1).

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

Further, there is a problem that a desired sealing strength cannot be obtained when heat-sealing on a carrier tape. This is particularly serious in polystyrene or polycarbonate carrier tapes that have become widespread in recent years, and it is known that the cover tape peels off during the transportation and storage of the taping package, and the internal electronic components fall off. ..

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

Japanese Unexamined Patent Publication No. 7-251860

The present invention solves the above-mentioned problems, has sufficient sealing strength and stable easy peeling property, and exhibits excellent antistatic property applicable to packaging of electronic parts while maintaining high transparency. It is an object of the present invention to provide a transparent conductive cover tape.

As a result of various studies, the present inventor has obtained a first intermediate layer made of a polyethylene-based resin and a second intermediate layer made of a blended resin of an ethylene / α-olefin copolymer and a styrene / butadiene block copolymer. A film was formed by a coextrusion method, and a resin composition in which conductive fine particles were dispersed in an acrylic resin was laminated on the second intermediate layer as a heat seal layer, and here, aluminum was used as the conductive fine particles. It has been found that the above-mentioned objectives can be achieved by using the particles of zinc oxide doped with the above.

That is, the present invention is characterized by the following points.
(1) A transparent conductive cover tape for heat-sealing the carrier tape.
The base film, the adhesive layer, the first intermediate layer, the second intermediate layer, and the heat seal layer are laminated in this order.
The first intermediate layer is a layer made of a polyethylene-based 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.
The heat-sealing layer is a layer made of a transparent conductive heat-sealing material in which conductive fine particles are dispersed in an acrylic resin, and the conductive fine particles are aluminum-doped zinc oxide particles. Transparent conductive cover tape.
(2) The transparent conductive cover tape according to 1 above, wherein the polyethylene-based resin forming the first intermediate layer is linear low-density polyethylene.
(3) 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. The transparent conductive cover tape according to 1 or 2 above.
(4) The transparent conductive cover tape according to any one of 1 to 3 above, wherein the acrylic resin has a glass transition temperature of 20 to 100 ° C.
(5) The transparent conductive cover tape according to any one of 1 to 4 above, wherein the total light transmittance is 70% or more and the haze is 30% or less.
(6) The transparent conductive cover tape according to any one of 1 to 5 above, wherein the conductive fine particles are needle-shaped particles or microspherical particles.

The present invention has found that the surface resistivity of a film is significantly reduced by laminating layers made of a combination of specific resins and anti-conductive materials in a specific order and method.

Therefore, the transparent conductive cover tape of the present invention can obtain a high anticonductivity effect with a small amount of anticonductivity material, and at the same time, can maintain high transparency and good sealing strength.

Further, since the intermediate layer formed by co-extruding the two layers secures the sealing strength and at the same time contributes to the easy peeling property, high sealing property is achieved even if the heat sealing layer is provided thinly, and further, smoothness with a small zip-up is achieved. A feeling of opening can be obtained.

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

It is a schematic sectional drawing which shows the transparent conductive cover tape of this invention. It is a schematic cross-sectional view which shows an example of the state in which the transparent conductive cover tape of this invention is used as a cover material, and is heat-sealed with a carrier tape.

The present invention described above will be described in more detail below.

<1> Layer Structure of the 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 used as a lid material and 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 on the intermediate layer 3. Is. Here, the intermediate layer 3 is composed of a coextruded film in which the first intermediate layer 3a and the second intermediate layer 3b are formed together by a coextrusion method.

Note that the film formation by the coextrusion method is performed by extruding a plurality of melted resins from a plurality of narrow slit-shaped gaps, unlike a laminating method in which simple single films are bonded together.

Therefore, the interface between the layers formed by coextrusion shows a very peculiar structure, which is significantly different from the layer structure by entanglement interaction such as self-adhesion by the laminating method. Specifically, the interface formed by coextrusion is considered to form an interlocking structure in which crystals of each resin penetrate each other, and has an extremely complicated structure.

Therefore, in the present invention, the only way to specify the intermediate layer is to express it as a layer formed by the coextrusion method, that is, the characteristics of the present invention can be expressed only by specifying the product by the manufacturing method. ..

When the transparent conductive cover tape of the present invention is applied as the lid material of the carrier tape, the cover tape of the present invention is laminated on the pocket portion 6 of the carrier tape 5 so that the surfaces of the heat seal layer 4 face each other. , Heat seal.

<2> Base film In the present invention, the base film is a film made of polyethylene terephthalate (PET), polyester such as polyethylene terephthalate, polyolefin such as polypropylene, polyamide such as nylon, and thermoplastic resin such as polycarbonate. Alternatively, a film stretched in the 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 laminating means.

A PET film can be particularly preferably used because it exhibits transparency, heat resistance and moisture resistance suitable for a cover tape.

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

In addition, if necessary, in order to prevent dust and dust from adhering to the surface and to prevent the generation of static electricity due to contact with other surfaces, the surface opposite to the side in contact with the adhesive layer, that is, the outermost surface. May be treated with antistatic treatment using a surfactant, an ionic liquid, a conductive polymer, a conductive carbon black, metal vapor deposition, conductive fine particles such as metal oxide, and the like.

The thickness of the base film can be appropriately set by those skilled in the art, but 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 an adhesive layer. Here, as the adhesive, any dry laminating adhesive can be used.

Adhesives for dry laminating include one-component or two-component curable vinyl-based, (meth) acrylic-based, polyamide-based, polyester-based, polyether-based, polyurethane-based, epoxy-based, rubber-based, solvent-based, and water-based adhesives. , Or an emulsion type or the like laminating adhesive 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.

The thickness of the adhesive layer can be appropriately adjusted, but is, for example, 1 to 10 g / m ² and preferably 2 to 5 g / m ² so as to give appropriate rigidity to the cover tape. If it is thinner than 1 g / m ² , the adhesive strength cannot be made uniform, and the rigidity required for stabilizing the zip-up can not be reduced.

Further, if it is thicker than 10 g / m ² , not only is it disadvantageous in terms of price, but also the rigidity becomes too strong, which may cause cracks in the cover tape.

<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 a coextrusion method. It consists of a film made of

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

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

In the present invention, the first intermediate layer is made of a polyethylene-based resin.

Here, the polyethylene-based resin includes linear (linear) low-density polyethylene, high-pressure low-density polyethylene, medium-density polyethylene, high-density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ionomer resin, and ethylene-acrylic. Acrylic acid is used as a polyolefin resin 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-based resin modified with an unsaturated carboxylic acid such as methacrylic acid, maleic anhydride, fumaric acid, or a mixture of two or more thereof.

It is particularly preferable to use linear low-density polyethylene in order to sufficiently exhibit the function of ensuring the sealing strength and enhancing the film-forming stability, and to impart good flexibility and transparency to the cover tape.

In the present invention, the linear low-density polyethylene uses a single-site catalyst such as a metallocene catalyst or a multi-site catalyst such as a Ziegler-Natta catalyst to prepare ethylene and an α-olefin having 3 to 20 carbon atoms at a low temperature and a low pressure. It is a copolymer obtained by copolymerizing 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.

Further, examples of the copolymerization method include a polymerization method of ethylene and α-olefin using a low pressure method, a slurry method, a solution method, a gas phase method and the like.

The second intermediate layer is a layer located on the heat seal layer side. This layer exhibits stable interlayer adhesive strength with the heat-sealing layer, and contributes to both sealing property and easy peeling property.

In the present invention, the second intermediate layer comprises 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 above-mentioned linear low-density polyethylene, transparency is improved, and it becomes easy to control the peel strength according to the blend ratio with polystyrene.

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

Further, as the monomer copolymerizable with these, isoprene, acrylonitrile, methacrylonitrile and the like may be contained in addition to butadiene. In addition to the 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. It may contain a mixture of two or more kinds.

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.

If the proportion of the polystyrene-based resin and the styrene-derived unit is too large in the resin composition, the transparency tends to decrease, while the adhesion between layers increases and the easy peelability tends to decrease. In addition, when co-extruded with the first intermediate layer, the film-forming property tends to decrease.

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 peeling property and sealing property can be achieved at the same time.

Here, the blend ratio of both 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 used, the desired seal strength (peeling strength), and the like. can.

From the balance with the first intermediate layer and the heat-sealing layer described later, the second intermediate layer has a temperature of 70 to 110 ° C, more preferably 82 ° C or higher in order to obtain a sealing strength and easy-opening property suitable for a cover tape. For example, it is preferable to have 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, 30 to 70% by mass of an ethylene / α-olefin copolymer and a styrene / butadiene block copolymer. It is made by blending with 70 to 30% by mass.

The blend ratio of both is more preferably 50 to 70% by mass of the ethylene / α-olefin copolymer and 50 to 30% by mass of the styrene / butadiene block copolymer, and even 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 styrene content is low and the Vicat softening point is too high beyond the above range, the flexibility of the layer is insufficient, and the sealing property and the adhesion between layers are impaired. On the contrary, if the styrene content is high and the Vicat softening point is too low, the zip-up becomes large and the easy peelability is impaired.

In the present invention, the Vicat softening point is a value measured based on the A120 method of JIS K7206.

The total thickness of the first and second intermediate layers is 15 to 50 μm, more preferably 20 to 45 μm. If the thickness of the entire intermediate layer is too thin, sufficient cushioning properties will not be exhibited and the sealing strength will not be guaranteed.

In addition, the film formation becomes unstable, and a uniform film cannot be formed. On the contrary, if it is too thick, the sealing temperature is not high and the sealing strength is not guaranteed unless the sealing time is lengthened, which is not preferable.

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 will be low, which is not preferable. On the contrary, if it is too thick, wrinkles, uneven thickness, and pinholes are likely to occur at the time of forming the intermediate layer, which is not preferable.

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

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

In addition, the first and second intermediate layers may contain any additive, if necessary, as long as the effects of the invention are not impaired. As such an additive, various resin additives generally used for adjusting the molding processability, productivity, and various physical properties of the resin film can be used. However, particles such as conductive fine particles are not included because of the influence on transparency, interlayer adhesion, easy peeling property, and the like.

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

The transparent conductive heat-sealing material has a glass transition point of preferably 20 to 100 ° C., more preferably 30 to 60 ° C. from the viewpoint of easy peeling property, heat-sealing property and blocking property. If the glass transition point is too low, the heat-sealing layer becomes soft, and the film-forming property and the easy peeling property are impaired. On the contrary, 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 according to JIS K7121.

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, and isobutyl (meth) acrylate.

However, (meth) acrylate means acrylate or methacrylate. Examples of the monomer copolymerizable with these include styrene-based monomers such as styrene, chlorostyrene, chloromethylstyrene, t-butylstyrene, and vinyltoluene. Specifically, polymethyl (meth) acrylate, polyethyl (meth) acrylate, polybutyl (meth) acrylate, methyl (meth) acrylate-butyl (meth) acrylate copolymer, random and block of methyl (meth) acrylate and styrene. Alternatively, a graft copolymer, a random, block or graft copolymer of ethyl (meth) acrylate and styrene, and the like can be mentioned.

In particular, a copolymer with styrene can be preferably used from the viewpoint of coating film forming property and the like.

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, and for example, the styrene content is It is 0 to 30% by mass, more preferably 0 to 20% by mass.

If the styrene content is too high, the glass transition point is lowered, and the coating film forming property and the easy peeling property may be impaired. On the contrary, when the styrene content is low, it may be difficult to form a homogeneous coating film.

By using these acrylic resins as the binder of the heat-sealing material, not only the desired heat-sealing property and easy peeling property are achieved, but also, for example, when a PET film particularly preferable as the base film is used. It is possible to prevent the occurrence of blocking.

Further, in the present invention, the conductive fine particles dispersed in the acrylic resin are aluminum-doped zinc oxide particles.
The shape of the conductive fine particles is not particularly limited, but is preferably needle-shaped or microspherical.

Aluminum Doping Zinc Oxide is obtained by substituting an oxygen atom on a zinc oxide molecule with an aluminum atom by an ion doping method. The particles made of aluminum-doped zinc oxide can be suitably used in the present invention.

By using needle-shaped aluminum-doped zinc oxide, high conductivity can be obtained and high transparency can be ensured with a small amount of addition.
Further, by using the microspherical aluminum-doped zinc oxide, it becomes possible to add a large amount of aluminum-doped zinc oxide, and high conductivity can be obtained.
Needle-shaped and microspherical aluminum-doped zinc oxide can also be used in combination.

The particle size of the needle-shaped particles preferably used in the present invention has an average length (average major axis) of 100 to 2000 nm, and more preferably 200 to 2000 nm. Further, the aspect ratio of the average length (average major axis) / average diameter (average minor axis) is 10 or more, preferably 20 to 30.
The fine spherical particles preferably used in the present invention are true spherical or elliptical spherical particles, and the particle size has an average length (average major axis) of 10 to 200 nm, more preferably 20 to 200 nm. The aspect ratio of average length (average major axis) / average diameter (average minor axis) is 1 to 3, preferably 1 to 1.5.

In the present invention, the average length and the average diameter are average values obtained by measuring any 30 pieces by observing with an electron microscope (SEM).

By using acicular particles of aluminum-doped zinc oxide as the conductive fine particles and dispersing them in an acrylic resin, high antistatic properties can be achieved 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 polystyrene or polycarbonate carrier tape, in combination with the action of the first and second intermediate layers, good sealing strength and peeling strength are achieved, and excellent sealing performance and ease of sealing are achieved. It is possible to achieve both peelability and peelability.

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

If 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 smaller than the above range, the required antistatic performance cannot be obtained, which is not preferable.

The thickness of the heat seal layer is 0.1 to 5 μm, particularly preferably 0.2 to 2 μm, from the viewpoint of transparency, sealing property and antistatic effect.

In the present invention, since the heat seal layer is made of a combination of the acrylic resin and aluminum-doped zinc oxide, a sufficient antistatic effect can be obtained even if the layer thickness is reduced.

In the present invention, the surface resistivity of the heat seal layer is in the range of ^{105 to 10 12 Ω} / □ at 22 ° C. and 40% RH. Further, at 23 ± 5 ° C. and 12 ± 3% RH, the charge attenuation time required from 5000 V to 99% attenuation is 1 second or less, and it has excellent electrostatic characteristics.

If the above surface resistance exceeds ^{10 12} Ω / □, the electrostatic diffusion effect becomes extremely poor, making it difficult to protect electronic components from electrostatic damage, and if it is less than 105 Ω / □, the external component is used. There is a possibility that electricity may be applied to the electronic component through the lid material, and there is a risk that the electronic component will be electrically destroyed.

On the other hand, when the charge decay time, which is a measure of the diffusion rate of the charge generated by static electricity, exceeds 1 second, the electrostatic diffusion effect becomes extremely poor, and it becomes difficult to protect the electronic component from static electricity destruction. The surface resistivity and charge decay time described above can be measured in accordance with the US military standard MIL-B-81705C.

The heat seal layer may contain additives such as a dispersion stabilizer, a surfactant, and an anti-blocking agent, if necessary.

The heat seal layer is formed on the second intermediate layer by the gravure coat method, the air doctor coat method, the blade coat method, the knife coat method, the rod coat method, the direct roll coat method, the reverse roll coat method, the slide coat method, and the slot o. It can be applied and 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 be inspected and confirmed from the top of the cover tape in an unopened state by visual inspection or camera inspection, such as the presence or absence of contents and the filling state.

When the cover tape of the present invention is opened from the carrier tape, peeling occurs between the layers between the second intermediate layer and the heat seal layer (delamination) at the sealing portion, and the heat between the heat seal layer and the carrier tape is generated. It has stable peeling performance regardless of the fusion 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.

If the peel strength is less than 100 gf / 15 mm, peeling occurs during transportation and storage of the package, and there is a risk that the contents may fall off. Further, 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, which is not preferable.

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 a relative humidity of 40%.

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 pop out, which is not preferable.

The zip-up here means that the cover tape and the carrier tape are heat-sealed using two heat seal bars having a width of 0.5 mm, and the maximum and minimum values of the peel strength when the cover tape and the carrier tape are peeled off are used. The difference with.

The zip-up measurement condition is a numerical value when the measurement length of 20 mm is peeled by 180 degrees under the condition of a peeling speed of 300 mm / min in an atmosphere of 23 ° C. and a 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 and the like, but polystyrene and polycarbonate are particularly preferable.

In addition, as antistatic measures, conductive carbon black fine particles, metal fine particles, conductive fine particles obtained by giving conductivity to metal oxides, organosilicon compounds or surfactants are kneaded into these resins, or those containing these. May be applied.

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

The raw materials used are as follows.
Polyolefin-based resin 1: Evolu SP2520, C6-linear low-density polyethylene manufactured by Prime Polymer Co., Ltd. Density 0.925.
Polyolefin-based resin 2: Evolu SP2020, C6-linear low-density polyethylene manufactured by Prime Polymer Co., Ltd. Density 0.916.
Polyolefin-based resin 3: Evolu SP1520 manufactured by Prime Polymer Co., Ltd., C6-linear low-density polyethylene. Density 0.913.
Polyolefin-based resin 4: Ultzex 2021L, C6-linear low-density polyethylene manufactured by Prime Polymer Co., Ltd. Density 0.919.
Polyolefin-based resin 5: Asaflex 810, styrene-butadiene block copolymer manufactured by Asahi Kasei Chemicals Co., Ltd. Styrene content 65% by mass.
Biaxially stretched PET film 1: E7415 manufactured by Toyobo Co., Ltd. 12 μm thick. Single-sided antistatic, single-sided corona treatment.
Adhesive 1: RU-40 / H-4 manufactured by Rock Paint Co., Ltd. Two-component curable urethane adhesive.
Acrylic resin 1: Mitsubishi Chemical Corporation Dianal LR series. Styrene-methacrylate copolymer. Glass transition point 50 ° C.
Conductive fine particles 1: Pastran AZO manufactured by Mitsui Mining & Smelting Co., Ltd. Fine-grained particles obtained by doping 98.5 parts by mass of zinc oxide with 1.5 parts by mass of aluminum. Particle diameter 20 nm.
Conductive fine particles 2: Aluminum-free zinc oxide powder. Particle diameter 20 nm.

<Experiment I>
[Example I-1]
Resin composition I-1 (Vicut softening point 85 ° C.) containing a first intermediate layer (thickness 20 μm) made of a polyolefin resin 1 and 60% by mass of the polyolefin resin 4 and 40% by weight of the polyolefin resin 5. A second intermediate layer (thickness 10 μm) made of the above was formed into a film 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 the biaxially stretched PET film 1 were dry-laminated via an adhesive layer made of an adhesive 1.

Next, a transparent conductive heat sealant obtained by dispersing 250 parts by mass of the conductive fine particles 1 in 100 parts by mass of the acrylic resin 1 is rolled on the surface of the second intermediate layer of the obtained laminate. The cover tape of the present invention was produced by applying and drying to a thickness of 2 μm by a coating method.

The surface resistivity, charge decay time, haze value, total light transmittance, peel strength, and zip-up of the obtained cover tape were measured under the following conditions. The measurement results are shown in Table 1 below.

<Evaluation method>
(Surface resistivity)
The measurement was carried out at 22 ° C. and 40% RH with a probe URS and an applied voltage of 10 V using a high resta UP manufactured by Mitsubishi Chemical Analytech Co., Ltd.

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

(Haze value and total light transmittance)
Measurement was performed using Haze Guard II manufactured by Toyo Seiki Seisakusho Co., Ltd. in accordance with JIS K7136 and JIS K7361.

(Peeling strength)
The obtained cover tape was heat-sealed on a polystyrene substrate at 150 ° C. for 0.5 seconds at 3.0 kgf / cm ² , and then at 23 ° C. under 40% RH, manufactured by Toyo Baldwin Co., Ltd. The peel strength was measured with the Tencilon universal testing machine HTH-100. (Peeling speed = 200 mm / min, 180 ° peeling)

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

[Example I-2]
The present invention is the same as in Example I-1 except that the resin composition I-2 containing 80% by mass of the polyolefin-based resin 4 and 20% by weight of the polyolefin-based resin 5 is used as the second intermediate layer. The cover tape of the invention was manufactured and evaluated.

[Example I-3]
The cover tape of the present invention was produced in the same manner as in Example I-1 except that the resin composition I-3 containing 45% by weight of the polyolefin resin 4 was used as the second intermediate layer. evaluated.

[Comparative Example I-1]
Example I-1 except that the conductive fine particles 2 are used as the conductive fine particles and a heat-sealing material obtained by dispersing 250 parts by mass of the conductive fine particles 2 in 100 parts by mass of the acrylic resin 1 is used. Cover tapes were manufactured and evaluated in the same manner as above.

[Comparative Example I-2]
A cover tape was produced and evaluated in the same manner as in Example I-1 except that a film made of a polyolefin resin 3 having a thickness of 30 μm was used for the first and second intermediate layers.

(Summary of results of Experiment I)
The cover tape of the present invention manufactured in the examples has a suitable surface resistance and a sufficiently short charge decay time, so that it has excellent electrostatic characteristics and satisfactorily protects electronic parts from electrostatic destruction and the like. can do. In addition, it has high transparency, and the state of the contents can be easily confirmed by camera inspection. Further, it has good peel strength and maintains easy-opening property while sufficiently sealing the contents. In particular, the zip-up of the peel strength is small, and an extremely smooth peeling feeling can be obtained.

Comparative Example I-1, which contained only ordinary zinc oxide particles not doped with aluminum in the heat seal layer, had a high surface resistivity, a long charge decay time, and was inferior in the electrostatic diffusion effect.
Comparative Example I-2, in which the second intermediate layer did not contain an ethylene / α-olefin copolymer and a styrene / butadiene block copolymer, had a low peel strength and was inferior in sealing property.

<Experiment II>
[Example II-1]
A first intermediate layer (thickness 20 μm) made of a polyolefin-based resin 2, and a second intermediate layer made of a resin composition II-1 containing 60% by mass of the polyolefin-based resin 2 and 40% by weight of the polyolefin-based resin 5. (Thickness 10 μm) was 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 the biaxially stretched PET film 1 were dry-laminated via an adhesive layer made of an adhesive 1.

Next, a transparent conductive heat sealant having 250 parts by mass of the conductive fine particles 1 dispersed in 100 parts by mass of the acrylic resin 1 was roll-coated on the surface of the second intermediate layer of the obtained laminate. The cover tape of the present invention was produced by applying and drying to a thickness of 2 μm by the method.
The surface resistivity, charge decay time, haze value, total light transmittance, peel strength, and zip-up of the obtained cover tape were measured under the same conditions as in Experiment I. The measurement results are shown in Table 2 below.

[Example II-2]
A first intermediate layer A (thickness 7.5 μm) made of a polyolefin resin 2, a first intermediate layer B (thickness 12.5 μm) made of a polyolefin resin 3, and a second made of a resin composition II-1. The intermediate layer (thickness 10 μm) was formed by coextrusion to obtain a film having a total thickness of 30 μm.
The cover tape of the present invention was produced and evaluated in the same manner as in Example II-1 except that this film was used as an intermediate layer.

[Example II-3]
The present invention is the same as in Example II-2, except that the resin composition II-3 containing 60% by mass of the polyolefin-based resin 3 and 40% by weight of the polyolefin-based resin 5 is used as the second intermediate layer. The cover tape of the invention was manufactured and evaluated.

[Comparative Example II-1]
Example II-1 except that the conductive fine particles 2 are used as the conductive fine particles and a heat-sealing material obtained by dispersing 250 parts by mass of the conductive fine particles 2 in 100 parts by mass of the acrylic resin 1 is used. Cover tapes were manufactured and evaluated in the same manner as above.

[Comparative Example II-2]
A cover tape was produced and evaluated in the same manner as in Example II-1 except that a film made of a polyolefin resin 3 having a thickness of 30 μm was used for the first and second intermediate layers.

(Summary of results of Experiment II)
The cover tape of the present invention manufactured in the examples has a suitable surface resistivity and a sufficiently short charge decay time, so that it has excellent electrostatic characteristics and satisfactorily protects electronic components from electrostatic damage and the like. can do. In addition, it has high transparency, and the state of the contents can be easily confirmed by camera inspection. Further, it has good peel strength and maintains easy-opening property while sufficiently sealing the contents. In particular, the zip-up of the peel strength is small, and an extremely smooth peeling feeling can be obtained.

Comparative Example II-1, which contained only ordinary zinc oxide particles not doped with aluminum in the heat seal layer, had a high surface resistivity, a long charge decay time, and was inferior in the electrostatic diffusion effect.
Comparative Example II-2 in which the second intermediate layer did not contain the ethylene / α-olefin copolymer and the styrene / butadiene block copolymer had low peel strength and was inferior in sealing property.

1. 1. Base film 2. Adhesive layer 3. Intermediate layer 3a. First intermediate layer 3b. Second middle layer 4. Heat seal layer 5. Carrier tape 6. Pocket part

Claims (6)

A transparent conductive cover tape for heat-sealing the carrier tape, which is formed by laminating a base film, an adhesive layer, a first intermediate layer, a second intermediate layer, and a heat-sealing layer in order. ,
The first intermediate layer is a layer made of a polyethylene-based resin.
The second intermediate layer is a layer made of a resin composition containing an ethylene / α-olefin copolymer and a styrene / butadiene block copolymer , and has a Vicat softening point of 82 to 85 ° C.
The first intermediate layer and the second intermediate layer are layers formed by a coextrusion method.
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 thickness thereof is 0.2 to 2 μm.
The mass ratio of the acrylic resin to the conductive fine particles is 10 to 400 parts by mass with respect to 100 parts by mass of the acrylic resin.
The conductive fine particles are aluminum-doped zinc oxide particles.
The above transparent conductive cover tape. 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 according to 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 according to any one of claims 1 to 4, wherein the total light transmittance is 70% or more and the haze is 30% or less. The transparent conductive cover tape according to any one of claims 1 to 5, wherein the conductive fine particles are needle-shaped particles or microspherical particles.

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