JPH0796585A - Cover material - Google Patents

Abstract

PURPOSE:To obtain a cover material having superior electrostatic characteristics and transparency, a high adhesion to a synthetic resin-made container, and also a good releasability therefrom and never blocking even when it is wound in a reeled state. CONSTITUTION:A cover material 1 is provided with a biaxially oriented resin layer 2 and a heat sealant layer in which conductive fine powder containing a barium sulfate as a main agent is dispersed in a thermoplastic resin that is a mixed resin of a polyester resin and a vinyl chloride-vinyl acetate copolymer resin. An intermediate layer 4 provided between the biaxially oriented resin layer and the heat sealant layer adjacently to the heat sealant layer is made of a resin composition composed of 30-70wt.% ethylene-alpha-olefin copolymer having a density of 0.915-0.940g/am<3> and 70-30wt.% styrene-butadiene block copolymer of 50 90wt.% styrene and 50-10wt.% butadiene.

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.

Further, when applied with a surfactant, 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.

In addition, 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 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

Further, the lid member is in the form of a tape having a predetermined width and is used for heat fusion to the carrier tape in a reel state. In this reel state, since the biaxially stretched resin film forming the lid material and the heat sealant layer are in contact with each other, the occurrence of blocking between them is a problem.
Further, a lid member which does not cause such blocking and which has contradictory properties such as sufficient adhesiveness to a carrier tape and good peelability has not yet been obtained.

The present invention has been made in view of the above circumstances and has excellent electrostatic characteristics and transparency, and has both high adhesion to a synthetic resin container and good peelability, and An object of the present invention is to provide a lid material that does not cause blocking even when wound in a reel state.

[0010]

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 located between the sealant layer and the heat sealant layer, wherein the heat sealant layer is a thermoplastic resin which is a mixed resin of polyester resin and vinyl chloride-vinyl acetate copolymer resin, and a conductive fine particle containing barium sulfate as a main component. The intermediate layer has a density of 0.91.
5 to 0.940 g / cm ³ of ethylene-α / olefin copolymer 30 to 70% by weight and styrene 50 to 90% by weight
And a styrene-butadiene block copolymer of 70 to 30% by weight of butadiene and 50 to 10% by weight of butadiene.

[0011]

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%.
The thermoplastic resin forming the heat sealant layer is polyester, which comprises an intermediate layer formed of a resin composition consisting of 70 to 30% by weight of a styrene-butadiene block copolymer of 90% by weight and 50 to 10% by weight of butadiene. Since it is a mixed resin of resin and vinyl chloride-vinyl acetate copolymer resin, there is no occurrence of blocking with the biaxially stretched resin layer, and conductive fine powder mainly containing barium sulfate contained in the heat sealant layer is Since the antistatic property can be imparted to the lid material without losing the transparency of the heat sealant layer, and peeling between the interlayer between the intermediate layer and the heat sealant layer or peeling due to cohesive failure inside the heat sealant layer is possible. The lid material can be reliably peeled off regardless of the heat fusion strength of the heat sealant layer.

[0012]

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, a lid material 1 includes a biaxially stretched resin layer 2 and an adhesive layer 3.
The heat-sealant layer 5 and the intermediate layer 4 which are sequentially laminated on the biaxially stretched polyester resin layer 2 are provided.

The biaxially stretched resin layer 2 is made of polyester resin,
It can be formed of a biaxially stretched film of polypropylene resin, nylon resin, polycarbonate resin or the like. By providing such a 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.
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 sandblast treatment in advance to enhance the adhesiveness with the adhesive layer 3. May be.

The adhesive layer 3 is made of low-density polyethylene, ethylene-α-olefin copolymer having a density of 0.915 to 0.940 g / cm ³ , polyethylene-vinyl acetate copolymer, ionomer, polypropylene, or modified products thereof. It can be formed by any one of the polyolefin, isocyanate-based and imine-based adhesives, and the thickness is preferably about 0.2 to 60 μm. Adhesive layer 3
Can be applied or extruded on a biaxially stretched resin film, and the intermediate layer 4 can be dry laminated or extruded laminated on the adhesive layer 3.

The intermediate layer 4 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 4 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.

If the amount of styrene constituting the styrene-butadiene block copolymer used for forming the intermediate layer 4 is less than 50% by weight, the tackiness of the film is increased and the handling becomes difficult. If it exceeds, the adhesiveness to the heat sealant layer at low temperature deteriorates, which is not preferable.

Then, in the intermediate layer 4, 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. If the amount of the ethylene-α / olefin copolymer is less than 30% by weight and the amount of the styrene-butadiene block copolymer is more than 70% by weight, the film forming property of the intermediate layer 4 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 4 and the heat sealant layer 5 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 4 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.

Further, in the lid member 1 of the present invention, the intermediate layer 4 may have a multi-layered structure in order to improve the film forming accuracy of the intermediate layer 4. In this case, the layer in contact with the heat sealant layer 5 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 material of the present invention having a two-layered intermediate layer. The intermediate layer 4 is composed of a first resin layer 4a and a second resin layer 4b. There is. In this case, the first resin layer 4a has a density of 0.915 to 0.940 g.
/ Cm ³ of ethylene-α-olefin copolymer. The second resin layer 4b in contact with the heat sealant layer 5 is composed of 30 to 70% by weight of an ethylene-α-olefin copolymer having a density of 0.915 to 0.940 g / cm ³ , 50 to 90% by weight of styrene 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 4a and the second resin layer 4b 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 4 includes a first resin layer 4a, a second resin layer 4b and a first resin layer. 4a and the 3rd resin layer 4c provided between the 2nd resin layer 4b. In this case, the first resin layer 4a 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 4b in contact with the heat sealant 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 third resin layer 4c is a layer having a larger mixing ratio of ethylene-α / olefin copolymer than the second resin layer 4b. Such first resin layer 4a and second resin layer 4
The thicknesses of b and the third resin layer 4c are 3 to 20 μm, respectively.
It can be about m.

The intermediate layer 4 as described above can be formed by a dry lamination method or an extrusion lamination method.

Since the lid 1 of the present invention comprises the intermediate layer 4 as described above, when the lid 1 thermally fused to the synthetic resin container is peeled off, the intermediate layer 4 and the heat sealant layer 5 are formed. Peeling between layers or heat sealant layer 5
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 5 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. If the peel strength is less than 100 g / 15 mm, peeling between the intermediate layer 4 and the heat sealant layer 5 or cohesive failure inside the heat sealant layer when transferring the container after the lid material is heat-sealed. There is a risk that peeling will occur and the contents will fall 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 180 at 23 ° C. and 40% RH.
Degree of peeling (peel rate = 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 5 to the synthetic resin container.

Here, whether peeling between layers (interlayer peeling) between the intermediate layer 4 and the heat sealant layer 5 or peeling due to cohesive failure in the heat sealant layer 5 is generated. It can be appropriately selected by controlling the heat sealing conditions. That is, stricter conditions for heat sealing (higher heating temperature, longer heating time, stronger pressure) can cause delamination between the intermediate layer 4 and the heat sealant layer 5, and thus the heat sealing can be performed. By loosening the conditions of time, peeling due to cohesive failure in the heat sealant layer 5 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 5 is a layer in which a 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 5 is a mixed resin of a polyester resin and a vinyl chloride-vinyl acetate copolymer resin. By mixing the vinyl chloride-vinyl acetate copolymer resin with the polyester resin in this manner, even when the polyester resin has a low glass transition temperature and causes blocking when the polyester resin is used alone, By mixing as described above, the biaxially stretched film and the heat sealant are wound in a reel shape, and blocking does not occur even when pressure-bonded.

The polyester resin used preferably has a glass transition temperature of 50 ° C. or higher. When the glass transition temperature of the polyester resin is lower than 50 ° C., blocking tends to occur when the heat sealant layer 5 is pressure-bonded to the biaxially stretched resin layer 2. The mixing ratio of each resin in the mixed resin of the polyester resin and the vinyl chloride-vinyl acetate copolymer resin used is 50 to 95% by weight of the polyester resin and 50 to 5% by weight of the vinyl chloride-vinyl acetate copolymer resin. It is preferably in the range of. When the amount of polyester 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. On the other hand, when the amount of vinyl chloride-vinyl acetate copolymer resin is less than the above mixing ratio,
The effect of mixing the vinyl chloride-vinyl acetate copolymer resin cannot be obtained.

Such conductive fine powder preferably has an average primary particle size of about 0.01 to 5 μm.

In the heat sealant layer 5, 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 heat sealant layer 5 has a thickness of 0.5.
.About.5 .mu.m, particularly preferably 0.8 to 2 .mu.m.

Such heat sealant layer 5 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 5 may contain additives such as a dispersion stabilizer, a surfactant and an antiblocking agent, if necessary.

Such a heat sealant layer 5 can be formed by coating on the intermediate layer 4.

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.

Since the cover material 1 of the present invention causes peeling between the intermediate layer 4 and the heat sealant layer 5 or peeling due to cohesive failure inside the heat sealant layer 5, heat to the synthetic resin container is increased. 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 adhesive strength between the intermediate layer 4 of the lid 1 and the heat sealant layer 5 or the breaking strength of the heat sealant layer 5 is 100 to 100.
Heat sealant layer 5 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 Alternatively, a conductive polymer formed on the surface of a plastic film may be used.

Next, the lid material of the present invention will be described in more detail with reference to experimental examples. (Experimental Example) A biaxially stretched polyester film (PET) (Spett 6140, manufactured by Toyobo Co., Ltd., thickness 12 μm, corona treated product) was prepared for the biaxially stretched resin layer.

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

Further, as an adhesive layer, low density polyethylene (LDPE) (Mirason 16 manufactured by Mitsui Petrochemical Co., Ltd.)
-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 70 to 90 are used.
As a styrene-butadiene block (SB) copolymer containing 30% by weight of butadiene and 30% by weight of butadiene, the following S.
A B copolymer was prepared.

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 In addition, in order to form the heat sealant layer, the following polyester resin, vinyl chloride-vinyl acetate copolymer resin, and conductive fine powder were prepared.

Polyester resin: Byron (glass transition temperature = 50 ° C.) manufactured by Toyobo Co., Ltd. Vinyl chloride-vinyl acetate copolymer resin: Vinylite VAGH manufactured by Union Carbide Co., Ltd. Conductive fine powder: Mitsui Mining & Smelting Co., Ltd. Pasteran IV average particle size = 0.1 μm Next, using each of these materials, first, after applying an adhesive to the PET film, the LDPE layer (thickness 20 μm) is used to form the following table by an extrusion lamination method. An intermediate layer (thickness: 30 μm) was formed under the mixing conditions of the L.LDPE and S.B copolymers shown in 1. After that, a heat sealant layer having a composition shown in Table 1 below (thickness: 2) was formed on the intermediate layer.
(μm) is formed by the gravure reverse method, and the lid material (Sample 1
.About.12) was prepared.

[0046]

[Table 1] Further, Sample 13 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 13), the haze degree, total light transmittance, surface The resistivity, charge decay time and blocking resistance were measured under the following conditions. In addition, a conductive polyvinyl chloride resin base material (XEG4 manufactured by Taihei Chemical Co., Ltd.)
7) Each of the above lid materials is heated to 150 using a heat seal bar.
Heat fusion was performed under the conditions of 0 ° C., 0.5 seconds and 3.0 kgf / cm ² , and then the peel strength was measured under the following conditions. (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. (Peeling strength measurement conditions) Tensilon universal tester manufactured by Toyo Baldwin Co., Ltd. at 23 ° C. and 40% RH
It was measured with HTH-100. (Peeling speed = 300 mm / min, 1
(Peeling at 80 °) (Blocking resistance) A lid material having a length of 100 m and a width of 50 mm was wound into a reel and allowed to stand in an environment of 40 ° C. and 90% RH for 24 hours, and the occurrence of blocking was observed.

The measurement results of the above items and the peeling form of each lid material are shown in Table 2 below.

[0049]

[Table 2] Further, the peeling strength and the occurrence of blocking were the same as above except that the conditions for heat-sealing the lid material to the conductive polyvinyl chloride resin substrate were 140 ° C., 0.4 seconds, and 1.0 kgf / cm ^2. The peel morphology was measured and the results are shown in Table 3 below.

[0050]

[Table 3] As shown in Table 2 and Table 3, Samples 1 to 5 have good transparency and electrostatic properties, and have a moderate peel strength between the intermediate layer and the heat sealant layer, or
Peeling due to cohesive failure occurred inside the heat sealant layer.

On the other hand, since the sample 6 was the polyester resin alone, blocking occurred. 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.
Had a high haze value and poor transparency, and Sample 8 had a large surface resistance value and a long charge decay time, and the function of preventing static electricity generation was insufficient. Further, in Samples 9 and 10, since the amount of vinyl chloride-vinyl acetate copolymer resin in the heat sealant layer was large, blocking did not occur, but there was no coatability. Furthermore, sample 11 is L / LDP of the intermediate layer.
Since the amount of E was slightly large and the sample 12 had a small amount of L·LDPE, the peel strength of the sample 11 was lower than the proper strength, and the sample 12 was too high.

Further, the sample 13 had insufficient haze and total light transmittance, and had low transparency.

[0053]

As described above in detail, according to the present invention, the heat sealant layer constituting the lid member is made of a thermoplastic resin which is a mixed resin of polyester resin and vinyl chloride-vinyl acetate copolymer resin, and sulfuric acid. It is a layer in which conductive fine powder containing barium as a main component is dispersed, and since this heat sealant layer does not cause blocking with the biaxially stretched resin layer, blocking is prevented even when the lid material is in a reel state, and this heat The cover material has good antistatic properties while maintaining transparency due to the sealant layer, 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. .915-0.940 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
Since it is formed of a resin composition consisting of 0 to 30% by weight, peeling between the interlayer of the intermediate layer and the heat sealant layer when peeling the lid material, or peeling due to cohesive failure inside the heat sealant layer, As a result, good peelability can be obtained while maintaining high adhesiveness of the heat sealant layer, and 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 ... Intermediate layer 4a ... 1st resin layer 4b ... 2nd resin layer 4c ... 3rd resin layer 5 ... Heat sealant layer 11 ... Carrier tape 12 ... Embossing part

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location B32B 27/36 7421-4F B65D 73/02 M

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 conductive fine powder containing barium sulfate as a main component is dispersed in a thermoplastic resin which is a mixed resin of polyester resin and vinyl chloride-vinyl acetate copolymer resin, and the intermediate layer has a density of 0.915. ~
From 30 to 70% by weight of 0.940 g / cm ³ ethylene-α-olefin copolymer, 50 to 90% by weight of styrene and 50 to 10% by weight of butadiene, from 70 to 30% by weight of styrene-butadiene block copolymer A lid member formed of the resin composition described above. 2. The lid material according to claim 1, wherein the polyester resin forming the heat sealant layer has a glass transition temperature of 50 ° C. or higher. 3. The mixing ratio of the polyester resin forming the heat sealant layer and the vinyl chloride-vinyl acetate copolymer resin is 50 to 95% by weight of the polyester resin and 50 to 5 of the vinyl chloride-vinyl acetate copolymer resin. The lid material according to claim 1, wherein the lid material is in a range of weight%. 4. 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 in any one of Claim 1 thru | or 3 characterized by the above-mentioned. 5. 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
The lid member according to any one of claims 1 to 4, which is not more than a second.