JP3427110B2 - Conductive resin sheet - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive resin sheet formed by molding a composite resin composition comprising polyurethane, polyvinyl chloride and a plasticizer having low volume resistivity. It can be used for a sheet-like molded product or a floor sheet requiring good conductivity and antistatic performance without deteriorating rubber elastic properties, material strength properties and the like. [0002] Conventionally, as a polyvinyl chloride thermoplastic elastomer, a material containing a plasticizer represented by DOP (-2-diethylhexyl phthalate) or the like or for the purpose of improving compression set has been known. Partially crosslinked NBR (acrylonitrile-
Blends of butadiene rubber) have been known for a long time. Further, an antistatic agent or a conductive filler typified by carbon black is added to the elastomer to form an antistatic sheet or a conductive sheet in a clean room or O.D.
It is used as flooring material for room A. [0003] However, the antistatic sheet or conductive sheet obtained therefrom is not satisfactory in load-bearing deformation resistance and material strength characteristics typified by compression set, and further improvement in conductivity is desired. Is the current situation. SUMMARY OF THE INVENTION An object of the present invention is to provide a conductive resin sheet excellent in rubber elasticity and material strength characteristics typified by good conductivity and compression set. . The present inventors have made intensive studies in view of the above-mentioned situation, and as a result, completed the present invention. That is, the present invention provides a polyvinyl chloride resin (1), a polyurethane (2), and a volume resistivity at 30 ° C. of 1 ×.
A resin composition comprising a phthalic acid plasticizer (3) having an ether bond in an alkyl chain of 10 ¹¹ (Ω-cm) or less, and an organic antistatic agent (4) and / or an inorganic solid electrolyte (5) Wherein a sea-island type phase-separated structure is observed by transmission electron microscopy, the size of the separated structure is 0.01 μm or more and 500 μm or less, and the polyurethane (2) comprises three More iso
Reaction with a compound having a cyanate group, or polymer
A high molecular weight linear compound having a terminal isocyanate group and 3
Obtained by reaction with a compound having one or more hydroxyl groups,
Tensile modulus in linear viscoelasticity measurement from 20 ° C to 70 ° C
7 × 10 ⁶ dyne / cm ² or more and 8 × 10
⁷ dyne / cm ² or less, and 20 parts by weight of polyurethane (2) per 100 parts by weight of polyvinyl chloride resin (1).
A conductive resin sheet formed by molding a resin composition containing not less than 180 parts by weight and not more than 180 parts by weight of a phthalic acid-based plasticizer (3) having an ether bond in an alkyl chain. The details of the present invention will be described below. The polyvinyl chloride resin (1) used in the present invention includes one of a vinyl chloride homopolymer resin, a chlorinated vinyl chloride resin, a vinyl chloride monomer and all monomers copolymerizable therewith. A vinyl chloride copolymer resin (for example, vinyl acetate-vinyl chloride copolymer, ethylene-
A vinyl chloride copolymer), a resin obtained by grafting a functional group such as a hydroxyl group to the above resin, or a resin obtained by reacting a reactive compound with a reactive compound to form a graft bond. Used as a mixture of two or more. The degree of polymerization of the polyvinyl chloride resin (1) is not particularly limited.
0 or less, more preferably 500 or more and 5000 or less, and further preferably 800 or more and 4000 or less. Further, a mixture of a polyvinyl chloride resin having a polymerization degree in the above range and a polyvinyl chloride resin having an arbitrary molecular weight may be used. The polyurethane (2) used in the present invention has a tensile elastic modulus in the range of 20 ° C. to 70 ° C. in linear viscoelasticity measurement of 7 × 10 ⁶ dyne / cm ² or more and 8 × 10 ⁷ d.
yne / cm ² or less, more preferably 1 × 10 ⁷ dyne
/ Cm ² or more and 7 × 10 ⁷ dyne / cm ² or less are used. By using such a polyurethane, the compression set of a sheet obtained is improved. In order to further improve the compression set of the sheet of the present invention, the compression set of the polyurethane (2) used alone is preferably 40 or less, more preferably 35 or less. Here, the compression set is a value measured according to the method of JIS K6301 compression set, the measurement temperature is 70 ° C., and the time for giving the strain is 22.
Time. Further, it is effective to use a polyurethane having a network structure as the polyurethane from the viewpoint of improving the compression set of the sheet. Such a polyurethane can be defined as having a tetrahydrofuran (THF) dissolved content of 10% or less. Further, such a polyurethane is obtained, for example, by reacting a polymer polyol with a compound having three or more isocyanate groups, or by reacting a high molecular weight linear compound having a polymer terminal with an isocyanate group with a compound having three or more hydroxyl groups. Of these, it is desirable to obtain a polyurethane according to a method in terms of cost performance. In order to further improve the compression set of the sheet of the present invention, the ratio of the compression elastic modulus of the polyvinyl chloride resin (1) to the compression elastic modulus of the polyurethane (2) used at 70 ° C. is 0.4. It is desirable to set it to 1.8 or less. In order to improve the tensile strength of the sheet of the present invention, it is preferable to use a polyurethane (2) having excellent compatibility with the polyvinyl chloride resin (1) to be used. Such polyurethanes include polyester-based polyurethane, polycaprolactone-based polyurethane,
Polyester-based polyurethanes, ether-ester-based polyurethanes containing a compound obtained by ester-bonding an ether-based diol and a dicarboxylic acid represented by diethylene glycol as main components, and natural organic compounds having a hydroxyl group represented by cellulose and saponified EVA (Ethylene-vinyl acetate copolymer), such as a compound obtained by a urethane reaction of a synthetic organic compound having a hydroxyl group and an isocyanate compound. Among these, it is particularly preferable to use polyester-based polyurethane, polycaprolactone-based polyurethane, polycarbonate-based polyurethane, and ester ether-based polyurethane. The isocyanate index of polyurethane (2) (number of isocyanate groups / number of hydroxyl groups)
Can also be controlled. In general, polyurethane is obtained by a polyaddition reaction between a compound having a hydroxyl group and a compound having an isocyanate group, but the number of functional groups contained in each compound is not fixed, and there are various polyurethanes. For example, saponified EVA (ethylene-vinyl acetate copolymer) or the like contains many hydroxyl groups in one molecule, so that the gelation point generated by the reaction with the isocyanate compound has a considerably low isocyanate index. It is difficult to uniquely determine the optimal isocyanate index depending on the number of functional groups of the compound used in this way, but it is preferably 0.6 or more and 1.2 or less. If this value is less than 0.6, the sheet may have a sticky feel when molded, and if it exceeds 1.2, the sheet may become yellow. When the polyurethane (2) to be used is obtained by urethane reaction of a polymer polyol with a compound having three or more isocyanate groups, the molecular weight of the polyol, one of the components of the polyurethane, is not particularly limited. However, a sheet obtained by using a polymer polyol having an average molecular weight of 300 or more and 5000 or less is preferable because it has excellent moldability. The ratio of the polyvinyl chloride resin (1) to the polyurethane (2) used in the present invention is not particularly limited. However, in order to improve the compression set characteristics of the obtained material, the polyvinyl chloride resin (1) is used. The amount of the polyurethane (2) is preferably at least 20 parts by weight, preferably at least 30 parts by weight, and more preferably at least 45 parts by weight with respect to 100 parts by weight. From the viewpoint of cost performance, the amount of the polyurethane (2) added is preferably 180 parts by weight or less, preferably 150 parts by weight or less, and more preferably 120 parts by weight or less based on 100 parts by weight of the polyvinyl chloride resin (1). . The plasticizer (3) used in the present invention is 3
0 Ri volume resistivity of ^{1 × 10 11 (Ω-cm} ) or less of a plasticizer der in ° C., good polyvinyl chloride resin compatible
Phthalic acid-based plasticizer having an ether bond in the alkyl chain
Is used. Examples of the phthalic acid plasticizer having an ether bond in the alkyl chain include, for example, the following general formula: (Where m1 and m2 are integers of 2 to 4, n
1, n2 is an integer of 1 to 4, and R ¹ and R ² each have 3 to ¹ carbon atoms.
5 represents an alkyl group. ) Can be used. Furthermore, the overall volume resistivity is 1 × 10 ¹¹
(Ω-cm), the above-mentioned plasticizer and di-2-phthalic acid containing no ether bond in the alkyl chain.
Polyvinyl chloride resin such as phthalic acid plasticizer represented by ethylhexyl (DOP), adipic acid plasticizer, sebacic acid plasticizer, trimellitate ester plasticizer, polyester high molecular weight plasticizer, epoxidized soybean oil One or two or more general plasticizers that are usually added to the rubber may be used in combination. The amount of these plasticizers is from 20 to 180 parts by weight, more preferably from 30 to 150 parts by weight, based on 100 parts by weight of the polyvinyl chloride resin. If the added amount is less than 20 parts by weight, not only the flexibility as an elastomer is lost but also a sufficiently low electric resistance value may not be obtained. On the other hand, 180
If the amount is more than the weight part, bleed out of the plasticizer and material strength may be affected. The sheet of the present invention includes an organic antistatic agent (4) for preventing static electricity and an inorganic solid electrolyte (5) such as sodium chloride and magnesium chloride for promoting ionic conduction.
It is added. In addition, other inorganic fillers such as calcium carbonate and talc, which are usually added to polyvinyl chloride resin, and flame retardants such as antimony trioxide and zinc borate, to the extent that various physical properties are not extremely reduced, and partial crosslinking Modifiers such as polyvinyl chloride, partially cross-linked acrylonitrile-butadiene rubber (NBR), and processing aids represented by acrylic resins can be added as needed. Further, a hydrolysis inhibitor represented by carbodiimide, which is usually added to polyurethane, a fungicide represented by chlorine, nitrogen, and silver-zeolite, and a UV stabilizer may be added as necessary. It is possible. Further, the composition used in the present invention may be blended with another resin to improve the conductivity of the other resin, and this blend may be formed into a conductive resin sheet. In this case, it is also possible to mix a compatibilizer of the composition with another resin as the third component. The sheet of the present invention can be obtained by molding a composition comprising the above-mentioned polyvinyl chloride resin (1), polyurethane (2) and plasticizer (3). The method for producing this composition is not particularly limited, and any method can be adopted. Specifically, the following method is exemplified. A method in which the polyurethane (2) is finely crushed by freeze pulverization or the like, and then blended with the polyvinyl chloride resin (1).
In this case, an apparatus used for blending is arbitrary, and examples thereof include a roll, a Banbury mixer, and an extruder. A method in which a polyvinyl chloride resin (1), a polyol and an isocyanate compound are added to a solvent such as tetrahydrofuran (THF) to cause a urethane reaction in the solvent, and then the solvent is evaporated. A method of obtaining a composite material by heating and melting a polyvinyl chloride resin (1), a plasticizer (3), a polymer polyol, and an isocyanate compound under a shearing force. In particular, the use of the above method is preferable for the sheet of the present invention because the material strength characteristics represented by tensile strength are improved. Further, the composition used for obtaining the sheet of the present invention is stained with a staining agent such as osmumic acid and then observed under a transmission electron microscope (TEM).
It has an island-type phase-separated structure, and the size of the polyurethane dispersed phase that is an island portion is 0.01 μm or more.
Must be less than 00 microns. If the size of the dispersed phase exceeds this range, the formability of the sheet of the present invention will be significantly reduced. In order to improve the formability, the size of the dispersed phase is preferably from 0.03 to 400 μm, more preferably from 0.05 to 300 μm. The sheet of the present invention can be molded by a molding method which can be used for ordinary thermoplastic resins, such as extrusion molding, injection molding, calender molding, blow molding and press molding. The sheet thus obtained has a low electric resistance, is a conductive resin sheet having excellent conductivity and excellent compression set and tensile strength, and is required to have conductivity and antistatic performance in a clean room, an OA room, It can be mainly used for sheet materials for floors in operating rooms of IC factories and hospitals. In particular, when using floor sheets for clean rooms, OA rooms, and IC factories, the resin sheet is excellent in colorability and opacity, so it is laminated with a polyvinyl chloride base sheet into which a large amount of conductive filler such as carbon black is kneaded. It is also possible to make it. EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited to these examples. Example 1 Polyester polyol obtained by condensation polymerization of 1,4-butanediol and adipic acid (Nippon Polyurethane Co., Ltd.)
Nipporan 4010, 80 parts by weight, number average molecular weight 2000) and isocyanurate-modified hexamethylene diisocyanate (trifunctional isocyanate compound) (trade name: Coronate HX, manufactured by Nippon Polyurethane Co., Ltd.) 15.8
Parts by weight (NCO / OH ratio = 1.02), and 25 ppm of DBTDL (dibutyltin dilaurate) as a catalyst
Were mixed and left in an oven at 120 ° C. for 2 hours to form a polyurethane. 0.5 thickness from this sample
A rectangular test piece having a width of 5 mm, a width of 5 mm and a length of 25 mm was cut out to obtain a sample for measuring dynamic viscoelasticity. Also, JIS
The thickness is 12.70 ± for measuring K6301 compression set.
Punched to 0.13 mm. Separately, the obtained polyurethane was finely crushed by freeze pulverization to obtain a fine polyurethane powder. 93.4 parts by weight of the thus obtained polyurethane fine powder was put into a Banbury mixer having an inner volume of 1700 cc and a casing temperature of 150 ° C., and further, an ethylene-vinyl chloride copolymer (Ryuron) obtained by a suspension polymerization method was used. E-2800, average polymerization degree: 2750, manufactured by Tosoh Corporation) 100 parts by weight, 2 parts by weight of barium stearate as a stabilizer, zinc 1 part by weight of stearic acid, amine scavenger (Nissan ferro organic chemical Co., Ltd., Product name BP-33
1) 1.5 parts by weight , 100 parts by weight of a phthalic acid plasticizer having an ether bond in an alkyl chain (Sansoizer C-1100 manufactured by Shin Nippon Rika Co., Ltd.), an antistatic agent (Shin Nihon
2 parts by weight of Plastat C-100 (manufactured by Rika Co., Ltd.) were stirred at a constant rotation speed, and kneaded for 15 minutes to obtain a composition. After the completion of kneading, the obtained composition was applied to a roll forming machine to form a sheet, and the thickness was 12.70 ± 0.1.
A sample for evaluation of compression set was formed by press molding so as to have a thickness of 3 mm. In addition, the composition is 1 mm thick, 70 mmφ.
To obtain a sheet, which was used as a sample for measuring electric resistance. Example 2 As a polyester polyol, a diol component is a mixture of ethylene glycol and 1,4-butanediol, an acid component is adipic acid, and a polyester polyol obtained by condensation polymerization of both (Sanyo) Sunstar 246 manufactured by Kasei Corporation
20), 80 parts by weight of isocyanurate-modified hexamethylene diisocyanate (Nippon Polyurethane Co., Ltd.)
13.4 parts by weight (NCO /
Except for using OH ratio = 0.85), a target composition was obtained by the same operation as in Example 1, and was molded and evaluated. [0032] [0033] [0034] The diol component as a third embodiment the polyester polyol is 1,6 -
Polyester polyol obtained by condensation polymerization of hexanediol with an acid component of a mixture of adipic acid and phthalic acid (Adeka New Ace F12 manufactured by Asahi Denka Co., Ltd.)
12-29) and 13.8 parts by weight of an isocyanurate-modified hexamethylene diisocyanate (trade name: Coronate HX, manufactured by Nippon Polyurethane Co., Ltd.)
A target composition was obtained by the same operation as in Example 1 except that the (CO / OH ratio = 0.85) was used, and the obtained composition was molded and evaluated. Comparative Example 1 Ethylene-vinyl chloride copolymer (Ryuron E-280)
0, average degree of polymerization: 2750, 100 parts by weight, manufactured by Tosoh Corporation) 2 parts by weight of barium stearate, 1 part by weight of zinc stearate as a stabilizer, amine supplement (trade name: BP manufactured by Nissan Ferro-Organic Chemical Co., Ltd.) -331) 1.5 parts by weight of a phthalic acid plasticizer having an ether bond in an alkyl chain (Sansoizer C-1100 manufactured by Shin Nippon Rika Co., Ltd.)
100 parts by weight, partially cross-linked NBR (PNC-38 acrylonitrile content 40%, manufactured by Nippon Synthetic Rubber Co., Ltd.)
4 parts by weight were kneaded for 10 minutes with the Banbury mixer having a casing temperature of 150 ° C. used in Example 1, stirred at a constant rotation speed, and kneaded for 15 minutes to obtain a composition.
The same evaluation was performed. Comparative Example 2 An antistatic agent (Plastat C-10 manufactured by Shin Nippon Rika Co., Ltd.) was added to 100 parts by weight of the ethylene-vinyl chloride copolymer.
A sample was obtained and evaluated in the same manner as in Comparative Example 1 except that 2 parts by weight of 0) was further added. Comparative Example 3 A sample was obtained and evaluated in the same manner as in Comparative Example 1 except that tricresyl phosphate was used as a plasticizer. The samples obtained above were evaluated by the following methods. (Evaluation of Electric Resistance) Volume resistivity and surface resistivity were measured at room temperature using an insulation resistance meter (TR8601 manufactured by Advantest Co., Ltd.). (Evaluation of Compression Set) JIS K6301
It measured according to. The initial strain is 25%, the temperature is 70 ° C,
After 22 hours, the strain was released and the residual strain was measured. (Evaluation of Tensile Strength) Tensile strength was measured at room temperature in accordance with JIS K6723. (Confirmation of Phase Structure) A sample was exposed to osmumic acid vapor, stained, and finished in an ultramicrotome at -100 ° C. in a 0.1 μm ultrathin section. Then, this was taken with an electron microscope (JEOL Ltd. J
EOL JEM-2000FX) using an accelerating voltage of 20
Observed at 0 kV. According to this observation, the component of polyurethane dyed to osmumic acid was 0.1 micron to 1 micron.
It was confirmed that the dispersed phase had a size of 00 microns. (Measurement of dynamic viscoelasticity) Viscoelasticity analyzer RSA which is a measuring device based on the non-resonant type forced vibration method
II (Rheometrics Far East Co., Ltd.), measurement frequency 10 Hz, measurement mode: 2
The storage modulus at 3 ° C. was measured. [Table 1] [Table 2] As described above, the sheet of the present invention is a conductive resin sheet exhibiting good conductivity, that is, low electric resistance, and having excellent compression set and tensile strength characteristics.

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Claims (1)

(57) [Claims] (1) Polyvinyl chloride resin (1), polyurethane (2), phthalic acid plasticizer (3) having an ether bond in an alkyl chain described in (1), And a resin composition comprising an organic antistatic agent (4) and / or an inorganic solid electrolyte (5), wherein a sea-island type phase separation structure is observed by transmission electron microscopy, and the separation structure is Having a size of 0.01 μm or more and 500 μm or less, wherein the polyurethane (2) is
Reaction with a compound having a cyanate group, or polymer
A high molecular weight linear compound having a terminal isocyanate group and 3
Obtained by reaction with a compound having one or more hydroxyl groups,
Tensile modulus in linear viscoelasticity measurement from 20 ° C to 70 ° C
7 × 10 ⁶ dyne / cm ² or more and 8 × 10
⁷ dyne / cm ² or less, and ² parts of polyurethane (2) per 100 parts by weight of polyvinyl chloride resin (1).
A conductive resin obtained by molding a polyvinyl chloride resin composition containing 0 to 180 parts by weight and a phthalic acid-based plasticizer (3) having an ether bond in an alkyl chain in a range of 20 to 180 parts by weight. Sheet. (Title 1) Volume resistivity at 30 ° C. is 1 × 10
Plasticizer of ¹¹ (Ω-cm) or less.