JPH0796967A - Cover material - Google Patents

Abstract

PURPOSE:To provide a cover material having an excellent electrostatic characteristic and transparency and further, both highly adhesive and easily separable characteristics to a synthetic resin container. CONSTITUTION:A cover material 1 is provided with a biaxial orientation resin layer 2, a heat-sealant layer 6 in which an electric conductive particles chiefly containing barium sulfate is dispersed in a thermoplastic resin, and an intermediate layer 5 adjacent to the heat sealant layer 6 and located between the biaxial orientation resin layer 2 and the heat sealant layer 6 and constituted of a resin compound made of 30-70wt.% ethylene-alpha.olefin copolymer having a density of 0.915-0.940g/cm<3> and 70-30wt.% styrene-butadien block copolymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lid member, and more particularly to a lid member used for a synthetic resin container.

[0002]

2. Description of the Related Art Conventionally, various parts, solid or liquid foods, and the like are housed in a synthetic resin container, and the opening is sealed with a lid member for distribution and storage.

For example, an electronic component is housed in each embossed portion of a carrier tape on which a large number of embosses are formed, and a lid material (cover tape) is heat-sealed and sealed on the carrier tape so as to cover the embossed portion. Carrier type taping is used. The carrier tape used for such embossed carrier type taping is usually formed of a material such as polyvinyl chloride, polystyrene, polyester, or polycarbonate which is easy to form into a sheet. The lid member also includes a biaxially stretched resin film and a heat sealant layer formed on one surface of the film. Then, there is a risk of deterioration and destruction of electronic components due to static electricity generated when the stored electronic components come into contact with the embossed portion of the carrier tape or the lid material and static electricity generated when the cover tape is peeled from the carrier tape. Therefore, a means for preventing this is required for the carrier tape and the lid material.

As a means for preventing the generation of static electricity in a carrier tape, conductive carbon fine particles and metal fine particles are kneaded or applied in the carrier tape. Further, as a means for preventing static electricity generation in the lid material, an antistatic agent such as a surfactant, conductive carbon fine particles, and metal fine particles are kneaded or applied to the heat sealant layer that is in direct contact with the electronic component. There is.

[0005]

However, in the conventional embossed carrier type taping as described above, the carrier tape and the lid material have extremely low transparency due to the conductive carbon fine particles as the antistatic agent contained therein,
There is a problem that it is difficult to confirm the electronic components stored in the embossed carrier type taping from the outside.

When a surfactant is applied, the surface condition of the heat sealant layer of the cover tape is changed,
There is a problem that the sealing property becomes unstable and causes a sealing failure, and the static electricity diffusion effect is largely dependent on the temperature and humidity during storage, so that a stable antistatic effect cannot be obtained.

Further, the heat-sealing of the lid material to the carrier tape requires a predetermined strength so that the lid material does not peel off during the transportation and storage of the embossed carrier type taping and the electronic parts do not fall off. To be done. However, if this heat fusion strength is too large, there is a problem that when the lid material is peeled off during the mounting process of the electronic component, the carrier tape vibrates and the electronic component pops out from the embossed portion of the carrier tape. It was Therefore, the lid material is required to be adhered to the carrier tape with sufficient strength and to have good peelability when the electronic component is used. Therefore, there is a problem that conditions such as temperature and time of heat sealing are strict. there were.

The present invention has been made in view of the above circumstances, and has a lid having excellent electrostatic characteristics and transparency, and having high adhesiveness to a synthetic resin container and good peelability. The purpose is to provide wood.

[0009]

In order to achieve such an object, the present invention provides a biaxially stretched resin layer, a heat sealant layer, and the biaxially stretched resin layer and the heat layer adjacent to the heat sealant layer. An intermediate layer positioned between the sealant layer and the heat sealant layer, wherein the heat sealant layer is a layer in which a conductive fine powder containing barium sulfate as a main component is dispersed in a thermoplastic resin, and the intermediate layer has a density of 0.915 to 0.940 g / cm
30-70 wt% of ethylene-α / olefin copolymer of ³ , styrene 50-90 wt% and butadiene 50-1
Styrene-butadiene block copolymer 7 with 0% by weight
The resin composition is composed of 0 to 30% by weight.

[0010]

The lid member includes a biaxially stretched resin layer, a heat sealant layer in which a conductive fine powder containing barium sulfate as a main component is dispersed in a thermoplastic resin, and a biaxially stretched resin layer adjacent to the heat sealant layer. It is located between the heat sealant layer, 30 to 70% by weight of ethylene-α-olefin copolymer having a density of 0.915 to 0.940 g / cm ³ , and styrene of 50 to 50%.
An intermediate layer formed of a resin composition comprising 70 to 30% by weight of a styrene-butadiene block copolymer of 90% by weight and 50 to 10% by weight of butadiene, and barium sulfate contained in a heat sealant layer as a main component. The conductive fine powder to give the antistatic property to the lid material without losing the transparency of the heat sealant layer, peeling between the intermediate layer and the heat sealant layer, or cohesive failure inside the heat sealant layer. Since it can be peeled off, the lid material can be peeled off stably and reliably regardless of the heat-sealing strength between the heat sealant layer and the carrier tape.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic sectional view of the lid member of the present invention.
In FIG. 1, the lid member 1 includes a biaxially stretched resin layer 2, an intermediate layer 5 and a heat sealant layer 6 which are sequentially laminated on the biaxially stretched resin layer 2 with an adhesive layer 3 and an adhesive layer 4 interposed therebetween. There is.

The biaxially stretched resin layer 2 can be formed of a biaxially stretched film of polyester resin such as polyethylene terephthalate (PET), polyolefin resin such as polypropylene, polyamide resin such as nylon. By thus providing the biaxially stretched resin layer 2, the lid member 1
Can be endowed with heat resistance. The thickness of the biaxially stretched resin layer 2 can be appropriately set according to the purpose of use of the lid material, and can be set to, for example, about 6 to 100 μm.

The adhesive layer 4 formed between the biaxially stretched resin layer 2 and the intermediate layer 5 makes it possible to uniformly apply heat and pressure during heat sealing. The adhesive layer 4 can be made of polyethylene, polyethylene vinyl acetate copolymer, ionomer, polypropylene, or any one of these modified polyolefins, and the thickness thereof is preferably about 10 to 60 μm. If the thickness of the adhesive layer 4 is less than 10 μm, the cushioning function is poor, and if it exceeds 60 μm, the heat sealing property is deteriorated. The adhesive layer 3 is for improving the laminating strength between the biaxially stretched resin layer 2 and the adhesive layer 4,
An isocyanate-based or imine-based adhesive can be used. If necessary, the surface of the biaxially stretched resin layer 2 on which the adhesive layer 3 is formed is subjected to surface treatment such as corona treatment, plasma treatment, and sand blast treatment in advance to improve the adhesiveness with the adhesive layer 3. You may raise it.

The adhesive layer 4 can be applied or extruded on a biaxially stretched resin film via the adhesive layer 3, and the intermediate layer 5 can be dry-laminated or extrusion-laminated on the adhesive layer 4. .

The biaxially stretched resin layer 2 and the intermediate layer 5 may be directly adhered to each other by the adhesive layer 3 and laminated without forming the adhesive layer 4. Also in this case, as the adhesive layer 3, an isocyanate type adhesive, an imine type adhesive or the like can be used. If necessary, the surface of the biaxially stretched resin layer 2 on which the adhesive layer 3 is formed can be subjected to surface treatment such as corona treatment, plasma treatment, and sandblast treatment in advance.

The intermediate layer 5 has a density of 0.915 to 0.940.
g / cm ³ ethylene-α / olefin copolymer 30 to 7
0 wt%, styrene 50-90 wt% and butadiene 5
It is formed of a resin composition comprising 70 to 30% by weight of a styrene-butadiene block copolymer with 0 to 10% by weight. The ethylene-α / olefin copolymer used for forming the intermediate layer 5 is a copolymer of ethylene and, for example, butene, pentene, hexene, heptene, octene, 4-methylpentene-1 or the like. Such ethylene-
density of 0.915 g / cm less than ³ alpha · olefin copolymer, or if it exceeds 0.940 g / cm ^3, a styrene - film forming property of the intermediate layer 4 in combination with butadiene block copolymer is lowered It is not desirable.

When the amount of styrene constituting the styrene-butadiene block copolymer used for forming the intermediate layer 5 is less than 50% by weight, the tackiness of the film is increased and the handling becomes difficult. When it exceeds the above range, the adhesion to the heat sealant layer 6 at a low temperature becomes poor, which is not preferable.

Then, in the intermediate layer 5, ethylene-α.
The mixing ratio of the olefin copolymer and the styrene-butadiene block copolymer greatly affects the peel strength when the lid material 1 is heat-sealed to the synthetic resin container and then peeled off, and the transparency of the lid material 1. To do. When the amount of ethylene-α / olefin copolymer is less than 30% by weight and the amount of styrene-butadiene block copolymer is more than 70% by weight, the film forming property of the intermediate layer 5 is lowered and the transparency of the lid material is also lowered, which is not preferable. . On the other hand, the amount of ethylene-α / olefin copolymer exceeds 70% by weight,
When the content of the styrene-butadiene block copolymer is less than 30% by weight, the adhesion between the intermediate layer 5 and the heat sealant layer 6 is too small, and the peel strength of the lid material is less than the appropriate strength, which is not preferable.

The thickness of the intermediate layer 5 is usually preferably about 10 to 60 μm. When the thickness of the intermediate layer is less than 10 μm, the film-forming property is poor, and when it exceeds 60 μm, the heat-sealing property of the lid material 1 is poor.

In the lid 1 of the present invention, the intermediate layer 5 may have a multi-layered structure in order to improve the film forming accuracy of the intermediate layer 5. In this case, the layer in contact with the heat sealant layer 6 is: Ethylene with a density of 0.915 to 0.940 g / cm ³
Styrene-butadiene block copolymer 70 to 30 wt% of α-olefin copolymer 30 to 70 wt%, styrene 50 to 90 wt% and butadiene 50 to 10 wt%
Need to be formed from a resin composition consisting of.

FIG. 2 is a schematic cross-sectional view showing an example of the lid member of the present invention having a two-layered intermediate layer. The intermediate layer 5 is composed of a first resin layer 5a and a second resin layer 5b. There is. In this case, the first resin layer 5a has a density of 0.915 to 0.940 g.
/ Cm ³ of ethylene-α-olefin copolymer. The second resin layer 5b in contact with the heat sealant layer 6 has a density of 0.915 to 0.940 g / cm ³ of ethylene-α / olefin copolymer of 30 to 70% by weight, styrene of 50 to 90% by weight and butadiene. It is formed by a resin composition comprising 70 to 30% by weight of a styrene-butadiene block copolymer with 50 to 10% by weight. The thickness of each of the first resin layer 5a and the second resin layer 5b can be about 5 to 30 μm.

FIG. 3 is a schematic cross-sectional view showing an example of the lid member of the present invention in which the intermediate layer has a three-layer structure. The intermediate layer 5 includes a first resin layer 5a, a second resin layer 5b and a first resin layer. 5a and the third resin layer 5c provided between the second resin layer 5b. In this case, the first resin layer 5a has a density of 0.9.
It is formed of 15 to 0.940 g / cm ³ of ethylene-α · olefin copolymer. The second resin layer 5b in contact with the heat sealant layer 6 has a density of 0.915 to 0.940.
g / cm ³ ethylene-α / olefin copolymer 30 to 7
0 wt%, styrene 50-90 wt% and butadiene 5
It is formed of a resin composition comprising 70 to 30% by weight of a styrene-butadiene block copolymer with 0 to 10% by weight. The third resin layer 5c is a layer having a larger mixing ratio of the ethylene-α / olefin copolymer than the second resin layer 5b. Such first resin layer 5a and second resin layer 5
The thicknesses of b and the third resin layer 5c are 3 to 20 μm, respectively.
It can be about m.

The intermediate layer 5 as described above can be formed by a dry lamination method or an extrusion lamination method. Moreover, the intermediate layer 5 can be formed by a normal film forming method such as an inflation method or a T-die method.

Since the lid 1 of the present invention includes the intermediate layer 5 as described above, the intermediate layer 5 and the heat sealant layer 6 are separated when the lid 1 thermally fused to the synthetic resin container is peeled off. Peeling between layers or heat sealant layer 6
Peeling occurs due to cohesive failure inside. The peel strength in this case is weaker than the heat fusion strength between the heat sealant layer 6 and the synthetic resin container, which will be described later, and is 100 to 12
It is preferably in the range of 00 g / 15 mm. When the peeling strength is less than 100 g / 15 mm, the peeling between the intermediate layer 5 and the heat sealant layer 6 or the heat sealant layer 5 when transferring the container after the lid material is heat-sealed.
There is a risk of peeling due to internal cohesive failure and the contents falling off. If the peel strength exceeds 1200 g / 15 mm, the synthetic resin container may vibrate when the lid material is peeled off, and the contents may pop out, which is not preferable. The peel strength is 18 at 23 ° C. and 40% RH.
It is a value of 0 ° peeling (peeling speed = 300 mm / min).

Therefore, the lid member 1 can be reliably peeled from the synthetic resin container after being heat-sealed by sufficiently increasing the heat sealing strength of the heat sealant layer 6 to the synthetic resin container.

Here, whether peeling between layers (interlayer peeling) between the intermediate layer 5 and the heat sealant layer 6 or peeling due to cohesive failure in the heat sealant layer 6 is generated. It can be appropriately selected by controlling the heat sealing conditions. That is, by deteriorating the conditions at the time of heat sealing (higher heating temperature, longer heating time, stronger pressure), delamination between the intermediate layer 5 and the heat sealant layer 6 can be caused, and the heat sealing can be performed. By loosening the conditions of time, peeling due to cohesive failure in the heat sealant layer 6 can be caused. As a specific example of the above heat-sealing condition, in the case of delamination, heating temperature = 140
˜200 ° C., heating time = 0.5 to 2.0 seconds, pressurization = 1.
0 to 5.0 kgf / cm ² , and in the case of cohesive failure, heating temperature = 100 to 150 ° C., heating time = 0.1 to 1.0
Second, pressurization = about 0.5 to 3.0 kgf / cm ² .

The heat sealant layer 6 is a layer in which conductive fine powder containing barium sulfate as a main component is dispersed in a thermoplastic resin.

The thermoplastic resin used for the heat sealant layer 6 is preferably a mixed resin of a polyurethane resin and a vinyl chloride-vinyl acetate copolymer resin, and the mixing ratio is 9: 1 to 1: 1.
It is preferably in the range of 4: 6. When the amount of the polyurethane resin is less than the above mixing ratio, the viscosity of the mixed resin composition increases and it becomes difficult to form the heat sealant layer by coating. Further, when the amount of the polyurethane resin is larger than the above mixing ratio, the peel strength is above the appropriate peel strength (1
It is less than 100 to 1200 g / 15 mm), which is not preferable. Examples of the above-mentioned polyurethane resin include Nippon Polyurethane Industry Co., Ltd.'s Nippon Polan 5120, Arakawa Chemical Co., Ltd.'s KL494, and the like. Examples of vinyl chloride / vinyl acetate copolymer resins include Vinylite VAGH, Vinylite VACH, and Vinylite VACA manufactured by Union Carbide.

Such conductive fine powder preferably has an average particle diameter of about 0.01 to 0.5 μm as primary particles.

In the heat sealant layer 6, the weight ratio of the above conductive fine powder to the thermoplastic resin is 1:10.
It is preferably in the range of 5: 2. If the amount of the conductive fine powder exceeds the above range, the transparency and heat seal strength will be insufficient. On the contrary, when the amount of the conductive fine powder is less than the above range, the peel strength does not satisfy the above-mentioned suitable peel strength (100 to 1200 g / 15 mm) and the surface resistivity and the charge decay time described later are obtained. It will not be possible.

The thickness of the heat sealant layer 6 is 0.5.
.About.5 .mu.m, particularly preferably 0.8 to 2 .mu.m.

Such heat sealant layer 6 has a surface resistivity of 10 ⁵ to 1 at 22 ° C. and 40% RH.
Within the range of 0 ¹² Ω, 23 ± 5 ° C, 12 ± 3%
Under RH, the charge decay time required to decay from 5000 V to 99% is 2 seconds or less, and it has excellent electrostatic characteristics. When the surface low efficiency above exceeds 10 ¹² Ω,
If the static electricity diffusion effect becomes extremely poor and it becomes difficult to protect electronic components from electrostatic breakdown, and if it is less than 10 ⁵ Ω, electricity may flow from the outside to the electronic components through the lid material. , There is a risk that electronic components will be destroyed electrically. On the other hand, if the charge decay time, which is a measure of the diffusion rate of charges generated by static electricity, exceeds 2 seconds, the electrostatic diffusion effect becomes extremely poor, and it becomes difficult to protect electronic components from electrostatic breakdown. The above surface resistivity and charge decay time are MIL-B-8, which is a military standard of the United States.
It can be measured according to 1705C.

The heat sealant layer 6 may contain additives such as a dispersion stabilizer, a surfactant and an antiblocking agent, if necessary.

Such a heat sealant layer 6 is formed on the intermediate layer 5 by 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 gravure coating method, a slide coating. Method, a slot olifill coating method or the like.

The cover material of the present invention as described above has such transparency that the total light transmittance is 50% or more and the haze value is 80% or less. Therefore, after the contents are filled in the synthetic resin container and the lid 1 is heat-sealed and sealed, the presence or absence of the contents and the filling state can be visually inspected and confirmed.

In the lid 1 of the present invention, peeling between the intermediate layer 5 and the heat sealant layer 6 or peeling due to cohesive failure inside the heat sealant layer 6 occurs. It has stable peeling performance regardless of fusion conditions. Such delamination will be described with reference to FIGS. 4 to 7. First, as shown in FIGS. 4 and 5, for example, a carrier tape 11 having an embossed portion 12 is attached to a cover material 1 as shown in FIG.
Are heat-sealed. This heat fusion is performed on both ends of the embossed portion 12 in a line shape with a predetermined width. In the illustrated example, the line-shaped heat-sealing portion H is shown by a shaded portion. In this state, the adhesion strength between the intermediate layer 5 of the lid 1 and the heat sealant layer 6 or the breaking strength of the heat sealant layer 6 is 100 to 100.
Heat sealant layer 6 in the range of 1200g / 15mm
Is smaller than the heat fusion strength between the carrier tape 11 and the carrier tape 11. Next, when the interlayer 1 and the heat sealant layer 5 are separated from each other when the cover material 1 is peeled off from the carrier tape 11, as shown in FIG. The heat sealant layer 5 is still heat-sealed to the carrier tape 11, and the intermediate layer 4
Peeling occurs between the heat sealant layer 5 and the heat sealant layer 5. Therefore, the lid member 1 is peeled off with the line-shaped heat-sealing portion H of the heat sealant layer 5 left on the carrier tape. On the other hand, when peeling the lid material 1 from the carrier tape 11 due to cohesive failure inside the heat sealant layer 5, as shown in FIG. Part of the material 5 is heat-sealed to the carrier tape 11 and part of the material 5 is removed together with the lid material 1, so that peeling occurs inside the heat sealant layer 5. Therefore, the lid member 1 is peeled off according to the breaking strength of the heat sealant layer 5 regardless of the heat fusion strength of the heat sealant layer 5 and the carrier tape 11.

That is, the lid member 1 of the present invention has the contradictory characteristics of high heat-sealing property to the carrier tape 11 and easy peeling property at the time of peeling.

As the synthetic resin container to which the lid material of the present invention as described above is applied, polyvinyl chloride (PV
C), polystyrene (PS), polyester (A-PE
T, PEN, PET-G, PCTA), polypropylene (PP), polycarbonate (PC), polyacrylonitrile (PAN), acrylonitrile-butadiene-styrene copolymer (ABS), etc. As conductive carbon fine particles, metal fine particles, conductive fine powder obtained by imparting conductivity to metal oxides such as tin oxide, zinc oxide, and titanium oxide, Si-based organic compounds, and those obtained by kneading or coating a surfactant, etc. Can be mentioned. Further, a PS-based resin sheet or ABS-based resin sheet having a composite plastic sheet formed by integrally co-extruding a PS-based or ABS-based resin film or sheet containing carbon black on one or both sides is also exemplified. To be

Next, the lid material of the present invention will be described in more detail with reference to experimental examples. (Experimental example) As a biaxially stretched resin layer, a biaxially stretched polyethylene terephthalate (PET) film (Toyobo Co., Ltd.)
Spetet 6140, thickness 12 μm, corona treated product) was prepared.

A polyethyleneimine solution (P-100 manufactured by Nippon Shokubai Chemical Co., Ltd.) was prepared for the adhesive layer.

Further, as an adhesive layer, low-density polyethylene (LDPE) (Mirason 1 manufactured by Mitsui Petrochemical Co., Ltd.)
6-P) was prepared.

Next, in order to form an intermediate layer, the following linear low density polyethylene (L.LDPE) as an ethylene-.alpha..olefin copolymer and styrene 50 to 90 are used.
As a styrene-butadiene block (SB) copolymer of 50% by weight and 50 to 10% by weight of butadiene, the following S.
A B copolymer was prepared and a monolayer film was obtained by an inflation method.

L·LDPE: Ultzex 3550A manufactured by Mitsui Petrochemical Co., Ltd. Density = 0.925 g / cm ³ S / B copolymer: Asaflex 8 manufactured by Asahi Kasei Co., Ltd.
10 Further, in order to form the heat sealant layer, the following polyurethane resin, vinyl chloride-vinyl acetate copolymer resin, and conductive fine powder were prepared.

Polyurethane resin: Nippon Polyurethane Industry Co., Ltd. Nipporan 5120 Vinyl chloride-vinyl acetate copolymer resin: Union Carbide Co., Ltd. Vinylite VAGH Conductive fine powder: Mitsui Mining & Smelting Co., Ltd. Pastran IV,
Average particle size = 0.1 μm Next, using each of the above materials, first, the LDPE layer (thickness: 20 μm) is formed on the adhesive layer formed on the PET film by the extrusion lamination method as shown in Table 1 below.
The intermediate layer (thickness 30 μm) was heat-bonded under the mixed condition of the L·LDPE and S · B copolymer shown in (3) to obtain a film of PET / adhesive layer / adhesive layer / intermediate layer. Then, a heat sealant layer (thickness: 2 μm) having the composition shown in Table 1 below was formed on the intermediate layer by a gravure reverse method to prepare lid materials (Samples 1 to 12).

[0046]

[Table 1] Further, Comparative Sample 1 was prepared in the same manner as Sample 1 in Table 1 above, except that the following conductive carbon fine particles were used as the conductive fine powder.

Conductive carbon fine particles: manufactured by Taitai Kako Co., Ltd. Printex XE2 average particle size = 0.4 μm Next, for each of the above-mentioned lid materials (Samples 1 to 12, Comparative Sample 1), the haze degree and total light The transmittance, surface resistivity and charge decay time were measured under the following conditions. Also, each of the above-mentioned lid materials was heat-sealed under the following two conditions using a heat seal bar on a conductive polyvinyl chloride resin base material (XEG47 manufactured by Taihei Chemical Co., Ltd.), and then under the following conditions. The peel strength was measured. (Measurement conditions of haze degree and total light transmittance) Suga Test Instruments Co., Ltd. color computer SM-5SC was used for measurement. (Measurement condition of surface resistivity) It was measured at 22 ° C. and 40% RH with Hiresta IP manufactured by Mitsubishi Petrochemical Co., Ltd. (Measurement condition of charge decay time) 23 ± 5 ° C, 12 ± 3% R
The time required for 99% attenuation from 5000 V under H is based on E according to MIL-B-81705C.
STATIC DECAY made by TS (Electro-Tech Systems, Inc)
Measured with METER-406C. (Heat fusion condition): 150 ° C, 0.5 seconds, 3.0 kgf / cm ² : 140 ° C, 0.4 seconds, 1.0 kgf / cm ² (Peeling strength measurement condition) 23 ° C, 40% Tensilon universal testing machine manufactured by Toyo Baldwin Co., Ltd. under RH
It was measured with HTH-100. (Peeling speed = 300 mm / min, 1
80 ° peeling) The measurement results and peeling form of the above items for each lid material are shown in Table 2 below.

[0048]

[Table 2] As shown in Table 2, Samples 1 to 6 have good transparency and electrostatic properties, and have an appropriate peel strength between the interlayer and the heat sealant layer, or inside the heat sealant layer. Peeling due to cohesive failure occurred.

On the other hand, sample 7 has a slightly high content of conductive fine powder in the heat sealant layer, and sample 8 has a slightly low content of conductive fine powder, so that sample 7 has a haze of 80.
% Or more, the transparency is insufficient, and the peel strength of sample 8 is below the appropriate strength, and the surface resistivity is 10 ¹³ Ω.
As described above, when the charge decay time was 2 seconds or more, the electrical characteristics were also deteriorated. In addition, since the amount of polyurethane resin in the heat sealant layer of Sample 9 is slightly large and the amount of polyurethane resin of Sample 10 is slightly small, Sample 9 is below the appropriate peel strength,
In Sample 10, the viscosity of the sealant ink was high and the coating operability was poor. Furthermore, Sample 11 is the L.
Since LDPE was a little large and sample 12 had a little L·LDPE, sample 11 was below the appropriate peel strength, and sample 12 had a haze of 80% or more and had poor transparency.

Comparative sample 1 had insufficient haze and total light transmittance, and had low transparency.

[0051]

As described in detail above, according to the present invention, the heat sealant layer constituting the lid material is a layer in which conductive fine powder containing barium sulfate as a main component is dispersed in a thermoplastic resin. Due to the heat sealant layer, the lid material has good antistatic properties while maintaining transparency, and the intermediate layer adjacent to the heat sealant layer and located between the biaxially stretched resin layer and the heat sealant layer has a density of 0.915-0.9
40 g / cm ³ of ethylene-α / olefin copolymer 30
To 70% by weight, 50 to 90% by weight of styrene, and 50 to 10% by weight of butadiene, the resin composition is 70 to 30% by weight of a styrene-butadiene block copolymer. At this time, peeling occurs between the intermediate layer and the heat sealant layer, or peeling occurs due to cohesive failure inside the heat sealant layer, thereby obtaining good peelability while maintaining high adhesiveness of the heat sealant layer. Therefore, it becomes easy to set the conditions for heat-sealing the lid member to the synthetic resin container.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a lid member of the present invention.

FIG. 2 is a schematic cross-sectional view showing another example of the lid material of the present invention.

FIG. 3 is a schematic cross-sectional view showing another example of the lid material of the present invention.

FIG. 4 is a perspective view showing a state in which the lid material of the present invention is heat-sealed on a carrier tape.

5 is a cross-sectional view taken along line VV of FIG.

FIG. 6 is a view corresponding to FIG. 5, showing a state in which the lid member is peeled off from the carrier tape.

FIG. 7 is a view corresponding to FIG. 5, showing a state in which the lid member is peeled off from the carrier tape.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Lid material 2 ... Biaxially stretched resin layer 3 ... Adhesive layer 4 ... Adhesive layer 5 ... Intermediate layer 5a ... 1st resin layer 5b ... 2nd resin layer 5c ... 3rd resin layer 6 ... Heat sealant layer 11 ... Carrier Tape 12 ... Embossed part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B32B 27/32 103 8115-4F B65D 65/40 A 77/20 L

Claims (5)

[Claims] 1. A heat sealant, comprising: a biaxially stretched resin layer, a heat sealant layer, and an intermediate layer adjacent to the heat sealant layer and located between the biaxially stretched resin layer and the heat sealant layer. The layer is a layer in which a conductive fine powder containing barium sulfate as a main component is dispersed in a thermoplastic resin, and the intermediate layer has a density of 0.915 to 0.940 g / cm ^3.
Ethylene-α / olefin copolymer of 30 to 70% by weight
And 50 to 90% by weight of styrene and 50 to 10 of butadiene
Styrene-butadiene block copolymer with 70% by weight
A lid member formed of a resin composition containing 30 to 30% by weight. 2. The weight ratio of the conductive fine powder and the thermoplastic resin forming the heat sealant layer is 1: 1.
It is in the range of 0-5: 2, The cover material of Claim 1 characterized by the above-mentioned. 3. The heat sealant layer has a surface resistivity in the range of 10 ⁵ to 10 ¹² Ω and a charge decay time of 2 or less.
The lid material according to claim 1 or 2, wherein the lid material has a duration of not more than a second. 4. The thermoplastic resin forming the heat sealant layer is a mixed resin of a polyurethane resin and a vinyl chloride-vinyl acetate copolymer resin, according to any one of claims 1 to 3. The described lid material. 5. The mixture ratio of the polyurethane resin constituting the heat sealant layer and the vinyl chloride-vinyl acetate copolymer resin is in the range of 9: 1 to 4: 6. Lid material.