JPH01176553A - Conductive thermoplastic sheet - Google Patents

Abstract

PURPOSE:To prevent the napping of a conductive fiber without lowering conductivity, by forming a crosslinked cured film having a specific film thickness based on an unsaturated resin and a reactive diluent to the surface layer of a conductive thermoplastic resin sheet. CONSTITUTION:A thermoplastic resin becoming a base material and a conductive nonwoven fabric are laminated, welded and integrated using an extrusion laminating method or a hot roll press bonding method. As a conductive fiber, a carbon fiber, a stainless steel fiber, a carbon composite synthetic fiber and a carbon coated synthetic fiber are pref. Next, surface treatment is applied to the surface of the conductive nonwoven fabric of the obtained conductive thermoplastic resin sheet. As the surface treatment, it is most pref. to use corona discharge treatment. Further, a curing composition based on an unsaturated resin and a reactive diluent is applied to the treated surface and cured to form a crosslinked cured film having a thickness of 1-10mum. As the curing means of tie curing composition, the irradiation with electron beam is pref.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a thermoplastic resin sheet having electrical conductivity on its surface.

(Prior Art) Methods for making plastic conductive include a method in which an antistatic agent is applied to the surface of the plastic and a method in which carbon black is added to the plastic as a conductive material. However, in the former case, the surface resistivity is at most 109
Furthermore, there are drawbacks such as the surface resistivity changing depending on the environmental humidity and the antistatic effect disappearing over time. In addition, the latter cannot obtain the desired electrical conductivity unless it is incorporated in such a large amount that the carbon black particles are present continuously within the sheet. However, if a large amount of carbon black is blended, there are drawbacks such as a significant decrease in the mechanical strength of the base resin and poor processability.

As a fundamental solution to the above-mentioned conventional problems, we have developed a conductive material in which a nonwoven fabric made of conductive fibers and thermofusible fibers (hereinafter referred to as conductive nonwoven fabric) is fused to a plastic sheet as a base material. A sheet is disclosed in Japanese Unexamined Patent Publication No. 155917/1983.

(Problems to be Solved by the Invention) However, when the surface of the conductive sheet disclosed in JP-A-58-155917 is lightly rubbed with a fingernail, cloth, etc., some of the conductive fibers on the surface layer are removed. There is a problem that it peels off from the base material and becomes fluffy.

This fuzzing phenomenon not only deteriorates the appearance of the conductive sheet, but also causes the conductive fibers to fall off from the sheet when rubbed strongly, contaminating the surrounding area, and even reducing the conductive performance, which is a major obstacle to practical application. It becomes.

The present inventors have made extensive studies to solve the above-mentioned problem, that is, the problem of fluffing of the conductive thermoplastic resin sheet.

As a result, a conductive thermoplastic resin sheet with a cross-linked cured film with a thickness of 1 to 10 μm mainly composed of an unsaturated resin and a reactive diluent formed on the surface layer conducts electricity without reducing its conductive performance. It was discovered that the fluffing of the fibers could be prevented, and the present invention was completed based on this knowledge.

(Means for solving problems) The present invention has the following configuration.

(1) A nonwoven fabric formed by irregularly intertwining thermofusible fibers and conductive fibers is bonded and fused to one or both sides of a thermoplastic resin film, and then surface treatment is applied to the surface of the nonwoven fabric. Further, a curing composition containing an unsaturated resin and a reactive diluent as main components is applied to the surface-treated surface, and the composition is cured to form a crosslinked cured film with a thickness of 1 to 10 μm. Thermoplastic resin sheet.

(2) The conductive thermoplastic resin sheet according to item 1 above, wherein the surface treatment is corona discharge treatment.

(3) The first method, wherein the curing means of the curing composition is an electron beam.
The conductive thermoplastic resin sheet described in .

(4) The conductive thermoplastic resin sheet according to item 1 above, wherein the conductive fiber is carbon fiber, stainless steel fiber, carbon composite synthetic fiber, carbon-coated synthetic fiber, or a mixture thereof.

Examples of the thermoplastic resin for the thermoplastic resin film used in the present invention include polyolefin resins such as polyethylene, polypropylene, ethylene/vinyl acetate copolymer, and ethylene/ethyl acrylate copolymer; polystyrene;
Styrenic resins such as acrylonitrinobebutadiene/styrene copolymer, acrylonitrile/styrene copolymer; acrylic resins such as polymethyl methacrylate; 6
-Nylon, 6-row nylon, 12-nylon, 6.1
Examples include polyamide resins such as 2-nylon; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyvinyl chloride polycarbonate, polyphenylene oxide, and mixtures thereof.

These resins include heat stabilizers, weather stabilizers, plasticizers, lubricants, slip agents, antistatic agents, charge transfer polymers, nucleating agents, flame retardants, tackifiers (petroleum resins, etc.), pigments, dyes, Inorganic fillers, organic fillers, etc. can be blended according to the purpose.In addition, heat-melting fibers used in conductive nonwoven fabrics include acrylic fibers, polyamide fibers, polyester fibers, polyolefin fibers, and polychlorinated fibers. There is no particular restriction as long as it is vinyl fiber or a mixture thereof and can be thermally fused to the thermoplastic resin film of the base material. These fibers may be blended with flame retardants, colorants, antistatic agents, charge transfer polymers, etc., if necessary.

The heat-fusible fiber has a fiber length of 5 to 100 mm and a fiber diameter of 0.
Those having a density of about 5 to 10 deniels are preferably used.

Next, conductive fibers include metal or metal compound composite synthetic fibers, metal or metal compound coated synthetic fibers, metal or metal compound coated glass fibers, metal or metal compound coated carbon fibers, carbon composite synthetic fibers, carbon coated synthetic fibers, carbon Examples include fibers, metal fibers, etc. and mixtures thereof. In addition, in the case of the present invention, in order to strengthen the adhesion between the crosslinked cured coating and the surface of the conductive thermoplastic resin sheet, it is necessary to perform a surface treatment on the surface of the conductive thermoplastic resin sheet to increase the wetting tension on the surface. It is.

- Corona discharge treatment is used as a surface treatment method for boat fishing. However, when corona discharge treatment is performed in the atmosphere, care must be taken because some conductive fibers lose their conductivity due to oxidation reactions caused by corona discharge. Incidentally, although corona discharge treatment in an inert gas atmosphere is possible, it is not practical due to many problems such as work safety and equipment.

When corona discharge treatment is performed in the atmosphere, it is desirable to use carbon fibers, stainless steel fibers, carbon composite synthetic fibers, carbon-coated synthetic fibers, or mixtures thereof, which do not show a decrease in conductive performance.

The conductive fiber has a fiber length of 5 to 100 mm and a fiber diameter of 1 to 30 mm.
A thickness of about μm is preferably used.

In addition to the heat-melting fibers and conductive fibers described above, the conductive nonwoven fabric of the present invention may contain fibers with a high melting point or fibers that do not exhibit meltability.

The conductive nonwoven fabric can be obtained from the above-mentioned thermofusible fibers and conductive fibers by a known method such as a binder method, needle punching method, hydraulic entanglement method using spun bonding, thermal bonding method, wet paper forming method, etc. The basis weight is heavy z1
ooy/= or less is preferably used.

The proportion of conductive fibers used in the production of conductive nonwoven fabric is 1
~99 Weight Section Weight Section Structure 3-70 Weight Section Weight Section. If the proportion of conductive fiber exceeds 999% by weight, it will be difficult to produce a conductive nonwoven fabric, or the adhesion to the thermoplastic resin film that is the base material will be insufficient, and conversely, if the proportion is less than 1% by weight, This is not preferable because it becomes difficult to provide good conductivity.

The unsaturated resins that are the main components of the curing composition used in the present invention include epoxy resins, polyester resins, polyurethane resins, polyamide #η5, and melamine resins, but especially those with high radiation activity. polyester,
Preferably used are molecules based on epoxy, polyurethane, polyether, and polyols with an acryloyl group introduced at the terminal or side chain, such as polyester acrylate, polyepoxy acrylate, polyurethane acrylate, polyether acrylate, and polyol acrylate. These usually have a molecular weight of 250 to 15
It is used in the form of an oligomer of about 0.00, and the number of acryloyl groups per molecule is 2 to 5.

In addition, as reactive diluents, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, neo Polyfunctional monomers such as pentyl glycol diacrylate, triacryloxyethyl phosphate, vinylpyrrolidone, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate,
Monofunctional such as tetrahydrofurfuryl acrylate, butoxyethyl acrylate, ethyl diethylene glycol acrylate, 2=-c tylhexyl acrylate, cyclohexyl acrylate, phenoxyethyl acrylate, 2-hydro-37 phenyloxyprobyl acrylate, dicyclopentadiene acrylate One type or a mixture of two or more types selected from these monomers can be used.

Various additives are further added to the curable composition as necessary. These additives include various natural or synthetic polymeric substances, fillers, pigments, dyes, matting agents,
Examples include plasticizers, viscosity modifiers, solvents, and various other auxiliary agents.

Examples of the above-mentioned polymeric substances include (meth)acrylic,
Urethane-based, butadiene-based, ethylene-based, vinyl chloride-based, vinylidene chloride-based, polyether-based, alkyd-based,
Polymers containing saturated or unsaturated groups belonging to polyester, polyamide, vinyl acetate, vinyl formal, vinyl butyral, vinyl pyrrolidone, vinyl alcohol, etc., copolymers, prepolymers, oligomers, cellulose, and their like. Examples include derivatives, rosin and its derivatives, phenol resins and its derivatives, petroleum resins, ketone resins, silicone resins, natural and synthetic oils and fats, waxes, and the like.

Examples of fillers include fibers and powders of glass, metals and metal compounds, silica, pallite, calcium carbonate, and the like.

Pigments include alumina white, clay, talc, extender pigments such as barium carbonate, barium sulfate, zinc white, yellow lead, ultramarine blue,
Inorganic pigments such as titanium oxide, zinc chromate, red iron oxide, carbon black, etc., Brilliant) Carmits 6B, Permanent Red R1 Benzidine Yellow, Lake Red C1
Examples include organic pigments such as phthalocyanine blue.

Examples of dyes include basic dyes such as magenta and rhodamine, direct dyes such as direct left scarlet and direct orange, and acidic dyes such as roserin and methanil yellow.

Examples of the matting agent include organic matting agents such as polyacrylonitrile powder, and inorganic matting agents such as powdered silica or modified products thereof.

Examples of the plasticizer include dibutyl phthalate, dioctyl phthalate, chlorinated paraffin, and tricresyl phosphate.

Examples of the viscosity modifier include bentonite, silica gel, aluminum octoate, and the like.

Examples of the solvent include various solvents belonging to ketone, alcohol, ester, ether, aliphatic, alicyclic, aromatic, hydrocarbon, and the like.

Other auxiliary agents include known antifoaming agents, leveling agents,
Examples include surfactants, ultraviolet absorbers, flame retardants, charge transfer polymers, and the like.

In addition, when the curing method mainly uses thermal energy such as a heating furnace, infrared ray irradiation, microwave irradiation, etc., radicals such as ketone peroxide, hydroperoxide, dialkyl peroxide, diacyl peroxide, etc. An initiator is used. In the case of curing at a relatively low temperature such as room temperature curing, for example, combinations of ketone peroxide, diacyl peroxide and metal salts, combinations of ketone peroxide, diacyl peroxide, hydroperoxide and reducing amines, etc. It is desirable to use an accelerator in combination.

In addition, when the curing means is ultraviolet rays, for example, benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin butyl ether, benzoin octyl ether, benzyl, diacetyl, methylanthraquinone,
Photoinitiators such as carbonyl compounds such as acetophenone and benzophenone, sulfur compounds such as diphenyl disulfide and dithiocarbamate, naphthalene compounds such as α-chloromethylnaphthalene, and metal salts such as anthracene and iron chloride are used.

The conductive thermoplastic resin sheet of the present invention can be obtained, for example, by the following method.

First, a thermoplastic resin serving as a base material and a conductive nonwoven fabric are stretched and fused together using a known method such as an extrusion lamination method, a hot roll compression method, or a hot press method. At this time, it is necessary to select temperature conditions such that the thermofusible fibers constituting the conductive nonwoven fabric completely melt and become integral with the base material. For example, in the case of extrusion lamination, the base material is thermoplastic resin! ↓The resin is melted and kneaded in an extruder at a temperature of about 180 to 280°C and extruded into a film through a T-die. Next, a conductive nonwoven fabric is superimposed on one or both sides of the resin film, and the base material and the conductive nonwoven fabric are fused and integrated by pressing with a pair of rolls heated to about 30 to 120°C. At this time, in order to facilitate the integration of the conductive nonwoven fabric and the base material, a heat-resistant plastic film such as a biaxially stretched polyester film or a Teflon film (thickness is preferably about 10 to 50 μm) is placed in contact with the conductive nonwoven fabric. ) may be stacked, pressure fused in this stacked state, cooled and solidified, and then the heat-resistant plastic film is peeled off and removed to obtain a conductive thermoplastic resin sheet.

The thickness of the conductive thermoplastic resin sheet can be arbitrarily selected within the range of 0.03 to 5.0 mm.

Next, the conductive nonwoven fabric surface of the conductive thermoplastic resin sheet obtained by the method described above is subjected to a surface treatment in order to improve the adhesion with the curable composition.

Surface treatments include chemical treatment, coupling treatment, primer treatment (polymer coating), surface grafting,
Various known methods such as ultraviolet irradiation treatment, plasma treatment (corona discharge treatment, glow discharge treatment, plasma jet treatment), plasma polymerization treatment, etc. can be used. Among these treatment methods, it is most preferable to use corona discharge treatment, which allows continuous production and is highly versatile. In the case of the present invention, it is desirable to use a corona discharge treatment device for treating conductors (corona discharge treatment devices for insulators are undesirable because sparks fly during discharge and scorching occurs. ). Further, it is desirable that the corona discharge treatment be performed immediately after manufacturing the conductive thermoplastic resin sheet. The surface wetting tension (measured according to ASTM-D-2578) of the surface-treated surface is 35 dyne/(7) or more, preferably 38
It is preferable to adjust to dyne/cIn or more.

Thereafter, the above-mentioned curing composition is further applied to the surface-treated surface, and the curing composition is cured to form a crosslinked cured film having a thickness of 1 to 10 μm on the surface.

As a coating device for the curing composition, a blade coater,
Knife coater, roll coater (3 roll coater)
, tie left coater, reverse roll coater), and various print type coaters such as screen, offset, gravure, letter press, and flexo coaters. A spray type coater may be used depending on the case.

The curing composition may be applied (solid printing) over the entire surface of the conductive thermoplastic resin sheet, or it may be applied partially using halftone plates (halftone dots) of various shapes. Good too.

The amount of the curing composition applied to the surface of the conductive thermoplastic resin sheet may be adjusted so that the thickness of the crosslinked cured film formed on the sheet surface is in the range of 1 to 10 μm, preferably 2 to 7 μm. preferable. If the thickness of the cured film is less than 1 μm, the occurrence of fluffing of the conductive fibers cannot be completely suppressed, and if it exceeds 10 μm, the surface resistivity will be 1o12Ω/
This is not preferable because the conductive performance deteriorates.

Curing methods for the curing composition include room temperature curing, heating furnace, infrared irradiation, microwave irradiation, etc., which mainly utilize thermal energy, ultraviolet irradiation, and ionizing radiation such as electron beams and R-rays. Although irradiation may be used, electron beam irradiation is preferred because of its productivity (curing time) and less deterioration of the base material due to heating.

The electron beam irradiation is performed in an N2 gas atmosphere (02 concentration of 400 ppm or less) using an electron beam accelerator using a scanning Jung beam method or a curtain beam method.

The conditions for curing the coating film are an electron beam voltage of 125 to 300 kV and a dose of about 1 to 20 Mrad.

(Examples) Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

The measurement methods used in the Examples and Comparative Examples are as follows.

(1) Melt flow rate ASTM D-1238 (temperature 230°C, load 3I 2-
1 #) Compliant.

(2) High melt flow rate ASTM D-1238 (temperature 230°C, load 10.2
Compliant with Yu).

(3) Isotactic pentad fraction measured based on MacO+Shikago-74Padan, 687 (1975).

This is the isotactic fraction in pentad units in the polypropylene molecular chain using +3C-NMR.

(4) Surface resistivity (Ω/mouth) → In case of sheet, Computing Digital Multimeter T manufactured by Takeda Riken
R6877 B, high resistance meter stack TR-3 made by Tokyo Denshi ■ The electrode is a circular electrode (positive electrode: outer diameter 70 mm φ disk, negative electrode: outer diameter 110 mm)
φ, inner diameter 80 mm φ ring shape) is used.

Measure using B only if the actual measured value is 107Ω or more.

Surface resistivity = 15π x Actual value (Ω) Example 1 Low melting point polypropylene fiber (melting point 128°C) with fiber diameter of 2 denier and fiber length of 51ix (melting point: 128°C) with 95% double chloride and fiber diameter of 13μ
m and 5% by weight of pitch-based carbon fiber (manufactured by Donatsuku) with a fiber length of 40nm and a fabric weight of 1og/weight by heat fusion method.
A conductive nonwoven fabric of m was obtained.

Then, isotactic pentad fraction (P)=0.
968, melt flow rate (MFR) -0.53,
! i'/10 questions, High Melt Flow Rate (HMFR)
= 23.59/1omin of highly crystalline propylene homopolymer and 1°3.5-)dimethyl-2,4,6-tris(3,5-di-t-phthyl-4-hydroxybenzyl)benzene 0.10 Weight% and tetrakis [methylene (3
, 5-di-t-butyl-4-hyroxyhydrocinamate)] Polypropylene pellets containing 0.1% by weight of Memetsu and 0.05% by weight of calcium stearate were melted in an extruder with a diameter of 65 mm. Kneaded T with a width of 600mm
The resin was extruded from the die into a film at a temperature of 240°C.

The conductive nonwoven fabric was superimposed on both sides of the resin film, and
Touch low # (metal o) with a diameter of 200 mm through warm water
-le) ,,! : The base material and the conductive nonwoven fabric were crimped and integrated with a chill roll (metal roll) having a diameter of s OOmw to obtain a conductive polypropylene sheet with a thickness of 0.8 mm. In addition,
In this step, a biaxially stretched polyester film with a thickness of 12 μm is further inserted into the conductive nonwoven fabric surface on the touch roll side, and after cooling the conductive polypropylene sheet,
The polyester film was peeled off. The surface resistivity of the conductive polypropylene sheet at this time was 10 on both sides.
It was 4-105Ω/mouth.

Next, both surfaces of the conductive polypropylene sheet were subjected to corona discharge treatment in the atmosphere using a corona discharge treatment apparatus for conductors. Wetting tension on both surfaces is 41 dyne/c
It was m. In addition, the surface resistivity of the conductive polypropylene sheet after corona discharge treatment is 10' to 10'Ω on both sides.
/ mouth, and was completely unchanged from before the corona discharge treatment.

Further, as a curing composition, a mixed composition consisting of 42 parts by weight of polyepoxy acrylate oligomer, 55 parts by weight of 2-hydroxypropyl acrylate, 2% by weight of a betaine surfactant, and 1% by weight of a polymerization inhibitor was prepared.

The combination was coated on the entire surface (one side) of the conductive polypropylene sheet using a gravure roll, and then irradiated under an N2 atmosphere (02
concentration 200ppm), acceleration voltage 140kV, dose 5Mr
A cross-linked cured film with a thickness of 3 μm was formed by irradiation with an electron beam using AD. Similarly, a crosslinked cured film with a thickness of 3 μm was formed on the other side as well. No fluffing of the conductive fibers was observed on either surface, and even when the surface was strongly rubbed with cloth, fingernails, etc., no fluffing of the conductive fibers occurred at all.

Moreover, the surface resistivity of the conductive polypropylene sheet after the formation of the crosslinked cured film was 104 to 105 Ω/hole on both sides, indicating good conductivity.

Example 2 85% by weight of polyvinyl chloride fibers (Teviron (trademark) manufactured by Teijin ■) with a fiber diameter of 2 denier and a fiber length of 51 mm and austenitic stainless steel fibers (manufactured by Nippon Seiren ■) with a fiber diameter of 8 μm and a fiber length of 50 mm. The fabric weight is 1 oi by using Naslon (trademark) 15% by weight and acrylic fiber as a binder.
3.0 parts by weight of dioctyl phthalate, 2.5 parts by weight of dibutyltin alkyl maleate, 05 parts by weight of butyl stearate, and 0.4 parts by weight of stearyl alcohol on a conductive nonwoven fabric of /m.
A polyvinyl chloride compound blended with 0.1 parts by weight of stearic acid was melt-kneaded in an extruder with a diameter of 65 mm, and extruded into a film at a resin temperature of 185°C through a T-die with a width of 500 μm.

The conductive nonwoven fabric was superimposed on both sides of the resin film, and 70
The base material and the conductive nonwoven fabric are crimped and integrated with a touch roll (metal roll) with a diameter of 200 mm and a chill roll (metal roll) with a diameter of 400 mm through warm water at 0.5 °C.
A conductive polyvinyl chloride sheet of mm was obtained. In addition, in this step, 1 was applied to the conductive nonwoven fabric surface on the touch roll side.
Furthermore, after inserting a biaxially stretched polyester film with a thickness of 12 μm and cooling the conductive polyvinyl chloride sheet,
The polyester film was peeled off. The surface resistivity of the conductive polyvinyl chloride sheet at this time was 10 on both sides.
It was 3-10'Ω/mouth.

Next, both surfaces of the conductive polyvinyl chloride sheet were subjected to corona discharge treatment in the atmosphere using a corona discharge treatment apparatus for conductors. Wetting tension on both sides is 43 dyne/c
It was m. In addition, the surface resistivity of the conductive polyvinyl chloride sheet after corona discharge treatment is 103 to 104 Ω on both sides.
/The mouth was completely unchanged from before the cycorona discharge treatment.

In addition, as a curing composition, 48% by weight of polyurethane acrylate oligomer, 45% by weight of neopentyl glycol diacrylate, and 6% by weight of extender pigment (alumina white).
A mixed composition containing 1% by weight of a polymerization inhibitor and a polymerization inhibitor was prepared.

The composition was rolled into a dotted gravure roll (dot area: 60%).
Then, the conductive polyvinyl chloride sheet surface (one side) was coated and accelerated under N2 atmosphere (O22 weight 200 ppm) using an electron curtain conveyor type electron beam irradiation device (Electron EPZ-2 model (trademark) manufactured by ESI). Electron beam irradiation was performed at a voltage of 160 kV and a dose of 12 Mrad to form a crosslinked cured film with a thickness of 7 μm. Similarly, a cross-linked cured film with a thickness of 7 μm was formed on the other side as well.

No fluffing of the conductive fibers was observed on any surface, and even when the surface was strongly rubbed with cloth, fingernails, etc., no fluffing of the conductive fibers occurred at all.

Moreover, the surface resistivity of the conductive polyvinyl chloride sheet after the formation of the crosslinked cured film was 10 3 to 10′ Ω/hole on both sides, indicating good conductivity.

Example 3 Acrylic nitrile/vinyl chloride copolymer fiber with fiber diameter of 15 denier and fiber length of 51 mm (Kanekalon SB (trademark) manufactured by Kanekabuchi Chemical Co., Ltd.) 90% by weight Austenitic stainless steel with fiber diameter of 8 μm and fiber length of 50 strands The fabric weight is 1 og/weight using the binder method using 10% by weight of fiber (Naslon (trademark) manufactured by Nippon Seiren ■) and acrylic resin as a binder.
rr? A conductive nonwoven fabric was obtained.

Next, GP-PS resin (Estyrene G-32 (trademark) manufactured by Nippon Steel Chemical Co., Ltd.) was melt-kneaded in an extruder with a diameter of 40 mm, and extruded into a film at a resin temperature of 230° C. through a T-die with a width of 300 iz. The conductive nonwoven fabric is superimposed on one side of the resin film, and the base material and the conductive nonwoven fabric are crimped and integrated with a pair of polygingerols (metal rolls) that have been passed through hot water at 60°C.
A conductive polystyrene sheet having a thickness of 0.3 mm was obtained. The surface resistivity of the conductive nonwoven fabric laminated surface of the conductive polystyrene sheet at this time was 104Ω/hole.

Then, the conductive nonwoven fabric laminate surface of the conductive polystyrene sheet was subjected to corona discharge treatment in the atmosphere using a corona discharge treatment apparatus for conductors. The wetting tension of the treated surface is 39 d
yne/cIrL. Furthermore, the surface resistivity of the conductive nonwoven fabric laminate surface of the conductive polystyrene sheet after the corona discharge treatment was 104Ω/hole, which was not different from that before the corona discharge treatment.

In addition, as a curing composition, 48% by weight of polyurethane acrylate oligomer, 45% by weight of neopentyl glycol diacrylate, and 6% by weight of extender pigment (alumina white).
A mixed composition containing 1% by weight of a polymerization inhibitor and a polymerization inhibitor was prepared.

The composition was applied to the entire conductive nonwoven fabric laminated surface (one side) of the conductive polystyrene sheet using a gravure roll, and an electron curtain conveyor type electron beam irradiation device (ESI) was applied.
N, using Electron EPZ-2 type (trademark) manufactured by
Acceleration voltage 140 in atmosphere (02 concentration 150 ppm)
irradiated with electron beam at kV and t 6 Mrad to a thickness of 5 μm
A cross-linked cured film was formed.

No fuzzing of the conductive fibers was observed on the laminated surface of the conductive nonwoven fabric on which the crosslinked cured coating was formed, and even when the surface was strongly rubbed with cloth, fingernails, etc., no fuzzing of the conductive fibers occurred at all. Also, the surface resistivity is 10'~105
It had good conductivity of Ω/mouth.

Example 4 Acrylic nitrile/vinyl chloride copolymer fiber (Kanekalon SB (trademark) manufactured by Kanekabuchi Chemical Co., Ltd.) with a fiber diameter of 15 denier and a fiber length of 51 mm, and carbon with a fiber diameter of 3 denier and a fiber length of 51 mm. A conductive nonwoven fabric having a basis weight of 109/1 was obtained by a binder method using 25 overlapping portions of coated polyester fibers and an acrylic resin as a binder.

Next, the ABS resin was melt-kneaded in an extruder with a diameter of 40 m, and extruded into a film at a resin temperature of 250° C. through a T-die with a width of 300 mm. The conductive nonwoven fabric is placed on both sides of the resin film, and the base material and the conductive nonwoven fabric are crimped and integrated with a pair of polygingerols (metal rolls) that have been passed through hot water at 80°C to a thickness of 1. A conductive ABS resin sheet was obtained. In this step, a biaxially stretched polyester film with a thickness of 25 μm was further inserted into the conductive nonwoven fabric surface on the touch roll side, and after the conductive ABS resin sheet was cooled, the polyester film was peeled off. Conductivity A at this time
The surface resistivity of the BS resin sheet was 105Ω/hole on both sides.

Then, both surfaces of the conductive ABS resin sheet were subjected to corona discharge treatment in the atmosphere using a corona discharge treatment apparatus for conductors. The wetting tension of the treated surfaces is 40 dyne/c.
It was m. Furthermore, the surface resistivity of the conductive ABS resin sheet after the corona discharge treatment was 105 Ω/hole on both sides, which was no different from that before the corona discharge treatment.

Further, as a curing composition, a mixed composition consisting of 54% by weight of polyepoxy acrylate oligomer, 45 overlapping parts of 2-hydroxyethyl acrylate, and 1% by weight of a polymerization inhibitor was prepared.

The composition was applied to the entire surface (one side) of the conductive nonwoven fabric laminated surface of the conductive ABS resin sheet using a gravure roll, and then applied using an electron curtain conveyor type electron beam irradiation device (Electron EPZ-2 model (trademark) manufactured by ESI). Nt
Acceleration voltage 140k in atmosphere (02 concentration 200ppm)
An electron beam was irradiated at a dose of 6 Mrad to form a crosslinked cured film with a thickness of 3 μm. Similarly, a crosslinked cured film with a thickness of 3 μm was formed on the other side as well.

The conductive ABS resin sheet with the cross-linked cured coating shows no fuzzing of the conductive fibers on both sides, and even if the surface is strongly rubbed with cloth, fingernails, etc., no fuzzing of the conductive fibers occurs at all. Ta. In addition, the surface resistivity was 105 to 106 Ω/hole, indicating good conductivity.

Example 5 Polyester polyacrylate 64 as curing composition
A mixed composition consisting of 30% by weight of polyol polyacrylate, 5% by weight of trimethylolpropane triacrylate, and 1% by weight of benzoyl peroxide was prepared.

The composition was coated with a bar coater on one side of a conductive polypropylene sheet (corona discharge treated) similar to that used in Example 1, and heat treated in an oven at 130°C for 5 minutes to form a crosslinked and cured sheet with a thickness of 7 μm. A film was formed. Similarly, a cross-linked cured film with a thickness of 7 μm was formed on the other side as well.

No fluffing of the conductive fibers was observed on either side.
Moreover, even if the surface was strongly rubbed with cloth, fingernails, etc., the conductive fibers did not become fluffed at all.

Further, the surface resistivity of the conductive polypropylene sheet after the formation of the crosslinked cured film was 10' to 105 Ω/hole on both sides, indicating good conductivity.

Example 6 Polyester polyacrylate 43 as a curing composition
A mixed composition consisting of 40% by weight of polyol polyacrylate, 15% by weight of trimethylolpropane triacrylate and 2% by weight of benzyl was prepared.

The composition was applied with a bar coater to one side of a conductive polyvinyl chloride sheet (corona discharge treated) similar to that used in Example 2, and irradiated with ultraviolet rays to form a crosslinked cured film with a thickness of 5 μm. Ta.

Similarly, a crosslinked cured film with a thickness of 5 μm was formed on the other side as well.

No fluffing of the conductive fibers was observed on either side.
Furthermore, even if the surface was strongly rubbed with cloth, fingernails, etc., no fluffing of the conductive fibers occurred.

Moreover, the surface resistivity of the conductive polyvinyl chloride sheet after the formation of the crosslinked cured film was 10 3 to 10′ Ω/hole on both sides, indicating good conductivity.

Comparative Example 1 A conductive polypropylene sheet was obtained in the same manner as in Example 1, except that the thickness of the crosslinked cured film was changed to 15 μm. No fuzzing of the conductive fibers was observed on either side of the sheet, and no fuzzing of the conductive fibers occurred even when the surface was strongly rubbed with cloth, fingernails, etc.

Moreover, the surface resistivity of the conductive polypropylene sheet after the formation of the crosslinked cured film was significantly deteriorated to more than 10'' Ω/mouth on both sides, and could hardly be called a conductive sheet.

Comparative Example 2 The surface resistivity was measured using the conductive polypropylene sheet in which no crosslinked cured film was formed in Example 1. Surface resistivity is 103-104Ω/ on both sides
The surface was in good condition, but when the surface was rubbed strongly with a fingernail or cloth, the conductive fibers became fluffy.

Comparative Example 3 A conductive polyvinyl chloride sheet was obtained in the same manner as in Example 2, except that the thickness of the crosslinked cured film was changed to 15 μm. No fluffing of the conductive fibers was observed on either side of the sheet, and no fluffing of the conductive fibers occurred even when the surface was strongly rubbed with cloth, fingernails, etc.

However, the surface resistivity of the conductive polyvinyl chloride sheet after the formation of the crosslinked cured film was significantly deteriorated to 1012 Ω/hole or more on both sides, and could hardly be called a conductive sheet.

Comparative Example 4 Surface resistivity was measured using the conductive polyvinyl chloride sheet in Example 2 in which no crosslinked cured film was formed. Surface resistivity is 103-104Ω/ on both sides
The surface was in good condition, but when the surface was rubbed strongly with a fingernail or cloth, the conductive fibers became fluffy.

(Effects of the Invention) The conductive thermoplastic resin sheet of the present invention, in which a 1 to 10 μm crosslinked cured film is formed on the surface layer of the conductive thermoplastic resin sheet and is firmly adhered to the base sheet, maintains good conductive performance. At the same time, it is a conductive fiber sheet with no visible fuzzing of the conductive fibers, and the conventional problems of deterioration in appearance due to the fuzzing of conductive fibers, contamination of the surrounding area due to shedding of conductive fibers, and deterioration of conductivity are avoided. I can't see it at all.

Therefore, the conductive thermoplastic resin sheet of the present invention independently
Or by combining with other materials, IC, LS
It can be suitably used for packaging of semiconductors such as I, electronic parts, precision mechanical parts, etc., and as a material for clean rooms.

that's all Patent applicant: Chisso Corporation

Claims (4)

[Claims] (1) After bonding and fusing a nonwoven fabric formed by irregularly intertwining thermofusible fibers and conductive fibers to one or both sides of a thermoplastic resin film, surface treatment is applied to the surface of the nonwoven fabric. A curing composition containing an unsaturated resin and a reactive diluent as main components is applied to the surface-treated surface, and the composition is cured to form a crosslinked cured film with a thickness of 1 to 10 μm. thermoplastic resin sheet. (2) The conductive thermoplastic resin sheet according to claim 1, wherein the surface treatment is corona discharge treatment. (3) The conductive thermoplastic resin sheet according to claim 1, wherein the curing means for the curing composition is an electron beam. (4) The conductive thermoplastic resin sheet according to claim 1, wherein the conductive fiber is carbon fiber, stainless steel fiber, carbon composite synthetic fiber, carbon-coated synthetic fiber, or a mixture thereof.