JPH0435847B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention involves attaching an adhesive, a glue, a thermoplastic resin, etc. to the back side of a molded article having two sides, which is formed from a thermoplastic resin composition containing fine metal particles, and imparting conductivity to the surface. Regarding the method. "Prior Art" Molded products obtained from thermoplastic resins, such as plasticized vinyl chloride resin, mixed with fine metal powder such as nickel, usually do not conduct electricity and have a volume resistivity of 10 ⁶ Ω.・It is a pressure-sensitive resin composition molded product that exhibits a value of at least cm and is in the so-called antistatic material range (10 ⁴ to 10 ⁷ Ω·cm) or semiconductive material range (10 ⁷ to ^{10 9} Ω·cm). Of course, if the content of fine metal particles is increased, it will reach the range of conductive materials (10 ^-3 to ^{10 4} Ω·cm), but the molded products made from the composition will be inferior in strength and cannot be put to practical use. In order to impart conductivity to a pressure-sensitive resin composition molded article, a method of pressing the molded article is known. For example, JP-A-49
−114798, JP-A-116996, JP-A-52-
No. 125796, JP-A-52-144798, JP-A-53-
The inventions described in No. 67856 and JP-A-53-79937 are both non-conductive resin compositions in which conductive particles are dispersed in a rubber elastic resin, and by applying a pressing force to this, it becomes conductive. It is a pressure-sensitive resistor designed to exhibit conductivity, and it cannot exhibit conductivity unless pressure strain is applied. "Problems to be Solved by the Invention" The present inventor has been intensively studying methods for obtaining various pressure-sensitive resin compositions, and has discovered that the compositions have two surfaces, a front and a back surface, and that Simply attach an adhesive, glue, or thermoplastic resin (hereinafter simply referred to as ``adhesive, etc.'') that exhibits no chargeability or conductivity to the back side of a molded product that is completely non-conductive. They discovered the surprising phenomenon that conductivity is imparted to the opposite surface to which an adhesive or the like is adhered without applying any pressing force, and have completed the present invention. That is, an object of the present invention is to provide a method for imparting conductivity to the surface of a molded article having two surfaces, obtained from a non-conductive pressure-sensitive resin composition containing fine metal particles, without imparting any distortion to the surface. There is something to do. "Structure of the Invention" That is, the gist of the present invention is a method for imparting conductivity to the surface of a molded article having two surfaces, the front and the back, obtained from a pressure-sensitive resin composition containing a thermoplastic resin and metal fine particles as main components. The present invention relates to a method for imparting conductivity to a pressure-sensitive resin composition molded article, which comprises bringing a non-conductive adhesive, glue, or thermoplastic resin into close contact with the back surface of the molded article. The method of the present invention will be explained in detail. Thermoplastic resins serving as raw materials for the pressure-sensitive resin composition used in the method of the present invention include, for example, vinyl chloride resin, vinylidene chloride resin, vinyl acetate resin, ethylene-vinyl acetate copolymer, polystyrene, ABS resin,
Acrylic resin, polyethylene, polypropylene,
Polyurethane resin, polyamide resin, acetal resin, polycarbonate, cellulose plastic,
Various resins such as silicone rubber, SBR, and NBR are used, but are not limited to these. Furthermore, the thermoplastic resin defined in the method of the present invention includes natural rubber. Furthermore, the thermoplastic resin that is the raw material for the pressure-sensitive resin composition used in the method of the present invention has a tensile modulus of 2×10 ⁴ Kg/cm ² as measured in accordance with JIS K6301.
Below, preferably 5×10 ³ Kg/cm ² , especially 1×10 ³
It is preferable to use one that is less than Kg/cm ² or the same value or less. The tensile modulus is usually adjusted by mixing a plasticizer, wax, resin oligomer, etc. with the thermoplastic resin. The method of the present invention has high utility value for vinyl chloride resins whose flexibility and processability of resin molded articles can be controlled using plasticizers. Vinyl chloride resins are all those produced by conventional methods such as suspension polymerization, bulk polymerization, fine suspension polymerization, or emulsion polymerization of vinyl chloride or a mixture of vinyl chloride and a comonomer copolymerizable with it. is used. Therefore, examples of comonomers that can be copolymerized with vinyl chloride include vinyl esters such as vinyl acetate, vinyl propionate, and vinyl laurate, acrylic esters such as methyl acrylate, ethyl acrylate, and butyl acrylate, methyl methacrylate, and ethyl acrylate. Methacrylic acid esters such as methacrylate, maleic acid esters such as dibutyl maleate and diethyl maleate, fumaric acid esters such as dibutyl fumarate and diethyl fumarate, vinyl ethers such as vinyl methyl ale, vinyl butyl ether, vinyl octyl ether, etc. , vinyl cyanides such as acrylonitrile and methacrylonitrile, α-olefins such as ethylene, propylene and styrene, vinylidene halides other than vinyl chloride or vinyl halides such as vinylidene chloride and vinyl bromide. The comonomer is 30% by weight or less in the constituent components of vinyl chloride resin,
It is preferably used in a range of 20% by weight or less. Of course, the comonomers are not limited to those mentioned above. Examples of plasticizers that control the flexibility of thermoplastic resins, particularly vinyl chloride resins, include di-n-butyl phthalate, di-n-octyl phthalate, di-2-ethylhexyl phthalate, and phthalate. diisooctyl acid, octyldecyl phthalate,
Phthalic acid plasticizers such as diisodecyl phthalate, butylbenzyl phthalate, di-2-ethylhexyl isophthalate, or phthalate esters of higher alcohols having about 11 to 13 carbon atoms, n-octyl-n-decyl trimellistate, Trimellitic acid plasticizers such as tri-2-ethylhexyl trimellitate, triisodecyl trimellitate, tri-n-octyl trimellitate, di-2 adipate
-Ethylhexyl, di-n-decyl adipate,
Diisodecyl adipate, di-2- azelaic acid
Fatty acid ester plasticizers such as ethylhexyl, dibutyl sebacate, di-2-ethylhexyl sebacate, phosphate esters such as tributyl phosphate, tri-2-ethylhexyl phosphate, 2-ethylhexyl diphenyl phosphate, and tricresyl phosphate. Epoxy plasticizers such as epoxidized soybean oil, epoxidized linseed oil, epoxidized tall oil fatty acid-2-ethylhexyl, liquid epoxy resins, etc. are used alone or in combination of two or more of these. do. The amount of plasticizer to be used is appropriately selected depending on the moldability, processability, workability of the composition, the purpose of the molded product, etc., but it is generally 30 to 300 parts by weight per 100 parts by weight of vinyl chloride resin. , preferably in the range of 50 to 200 parts by weight. In addition, when the composition used in the method of the present invention is a sol composition, a part of the plasticizer is used as a diluent such as texanol isobutyrate, dodecylbenzene, or kerosene, or as a swellable vinyl chloride resin such as toluene or xylene. It can be replaced with an organic solvent and may be used in the form of an organosol. The amount of the diluent and organic solvent to be added is appropriately determined depending on the application. Examples of the metal of the metal fine particles, which is another component of the pressure-sensitive resin composition, include nickel, chromium, cobalt, zinc, lead, iron, copper, titanium, silver, gold, platinum, and mixtures or alloys thereof. is used. The metal fine particles desirably have a particle size in the range of 0.05 to 40 microns, preferably 0.1 to 10 microns. Among these metal fine particles, it is preferable to use nickel fine particles in consideration of ease of acquisition, effectiveness, and economy, and the nickel fine particles have a specific surface area of 0.5 m ² /g or more and an apparent density of 1 g. /cm ³ or less is preferably used. The above specific surface area values were determined using the continuous flow method (measuring device: Quantachrome MONOSORB;
The apparent density is
Values measured in accordance with ASTM, B329-76. Furthermore, the average particle diameter is a value expressed as a particle size parameter measured using a Fisher subsieve sizer, and this measurement method is a type of air permeation method. In other words, when air at a constant pressure passes through a powder packed bed with a certain particle size, a pressure drop occurs depending on the particle size, and since the pressure ratio before and after filling is a function of the surface area, this can be converted to the average particle size. This is the obtained value. Most preferably, the nickel powder is a particle having an irregular shape, having many protrusions on the surface, and consisting of a chain structure of particles having a small cross-sectional area. Therefore, the amount of metal fine particles contained in the pressure-sensitive resin composition is preferably within the range of 10 to 40% by volume of the pressure-sensitive resin composition. In preparing the composition, the metal fine particles are usually added in parts by weight based on their specific gravity. For example, if the thermoplastic resin is vinyl chloride resin and the metal fine particles are the above-mentioned nickel particles, vinyl chloride resin
The nickel fine particles are used in a range of 100 to 1200 parts by weight per 100 parts by weight. In addition to the above-mentioned components, other additives such as stabilizers, lubricants, ultraviolet absorbers, antioxidants, colorants, and fillers can also be added to the pressure-sensitive resin composition. The method for preparing a pressure-sensitive resin composition and the method for producing a molded article may be performed using, for example, vinyl chloride resin as a thermoplastic resin,
A case where nickel powder (fine particles) is used as the metal fine particles will be explained. The pressure-sensitive resin composition is produced by adding vinyl chloride resin, a plasticizer, nickel powder, and other additives as necessary, and uniformly mixing and kneading the mixture. If the composition uses vinyl chloride resin manufactured by suspension polymerization or bulk polymerization, it is hot-dry blended using a high-speed stirrer, etc., then uniformly stirred using a Banbury mixer, and then mixed using a calender roll or the like. It is then formed into a film or sheet. On the other hand, in the case of a composition using a vinyl chloride resin manufactured by emulsion polymerization method or fine suspension polymerization method, the above-mentioned components are uniformly dispersed in a sol form and peeled off by a method such as knife coating. It is coated onto a base material having properties, heated to gel, and formed into a film or sheet, or formed into a cast molded product, which is gelled in a mold. However, when the content of nickel powder is large, it is desirable to prepare the pressure-sensitive resin composition using the above-mentioned hot dry blending method. In addition, by using vinyl chloride resin obtained by emulsion polymerization method or fine suspension polymerization method together with vinyl chloride resin obtained by suspension polymerization method or bulk polymerization method, the former vinyl chloride resin can be A pressure-sensitive resin composition can be prepared by kneading at a temperature lower than the kneading temperature, and molded articles can be manufactured at a lower temperature. The pressure-sensitive resin composition is produced by extruding a strand using an extruder or the like, and then using a pelletizer to make a granulated pressure-sensitive resin composition. It may be processed into a molded article by methods such as molding and compression molding. Therefore, the molded product used in the method of the present invention needs to have two surfaces, a front surface and a back surface, and a simple block molded product that does not have both mutually parallel planes is not suitable. Specifically, a film or a sheet is suitable. Although these molded products have fine metal particles dispersed therein, they do not have electrical conductivity and exhibit a volume resistivity of 10 ⁴ Ωcm or more, usually 10 ⁵ Ωcm or more, preferably about 10 ⁶ Ωcm. The product exhibits conductivity in the thickness direction when pressed, that is, it is a molded product made of a pressure-sensitive resin composition. The method of the present invention involves applying a non-conductive adhesive, glue, or thermoplastic resin to the back side of a molded product having two surfaces, as described above, and then applying the adhesive to the opposite side of the molded product. In other words, the purpose is to impart conductivity to the surface. In the method of the present invention, the distinction between the front surface and the back surface of a molded article is not based on the shape of the molded article or the mode of use, but for convenience, the surface to which an adhesive or the like is to be adhered or to which it is adhered is defined as the back surface. In addition, this adhesion is usually achieved by forming a layer of adhesive or the like on the back side of the molded product, but the thickness, width, length, planar shape, etc. of this layer can be changed by the method of the present invention. It is selected according to the purpose of the molded article imparted with conductivity. There are no particular restrictions on the adhesive as long as it is non-conductive, such as a type dissolved in a solvent or a hot melt type. Specifically, urea resin adhesives, melamine resin adhesives, phenolic resin adhesives, α-olefin resin adhesives, water-based vinyl urethane adhesives, epoxy resin adhesives, vinyl acetate resin adhesives (solution type) adhesives, vinyl acetate resin emulsion adhesives, acrylic resin emulsion adhesives, cyanoacrylate adhesives, polyurethane adhesives, chloroprene adhesives, nitrile rubber adhesives, SBR adhesives, natural rubber adhesives adhesives, cellulose adhesives, starch adhesives, polyvinyl alcohol aqueous solution adhesives, and the like are used. Further, the thermoplastic resin, which is one component of the pressure-sensitive resin composition, can be dissolved in a solvent or a plasticizer or extrusion laminated as it is to form an adhesive or the like. "Adhesion" of an adhesive or the like means that the adhesive or the like adheres tightly to the back surface of a molded article, and the method is not particularly limited as long as it can be tightly attached. For example, methods such as painting, applying, painting, spraying, dipping, melting, laminating, etc. in which the adhesive or the like is directly applied to the molded product may also be employed. Alternatively, a method may be adopted in which an adhesive or the like is applied in advance onto a carrier such as a sheet, pulp fiber, woven fabric, or knitted fabric, or a so-called adhesive tape or adhesive tape is applied to the molded product. For adhering the adhesive or the like, an appropriate method may be adopted depending on the shape of the molded product, its intended use, etc. According to the method of the present invention, a non-conductive adhesive is applied to the back side of a molded product having two surfaces, which is usually made from a non-conductive resin composition containing a small amount of metal particles of about 10 to 40 vol%. By adhering adhesive, glue, thermoplastic resin, etc., the resistance on the opposite side of the adhesion is significantly reduced, and even without pressing,
Becomes conductive. The reason why such a phenomenon occurs is unknown. Molded products manufactured by the method of the present invention have high utility value as wiring boards, keyboards, resistance adjustment materials, sensors, and the like. Next, the method of the present invention will be explained in detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. Example 1 The following ingredients were hot-dry blended, and the dry blend was heated and kneaded using a mill roll to form a 0.3 mm thick sheet made of a pressure-sensitive resin composition. Vinyl chloride resin (average degree of polymerization 1900)
100 parts by weight Di-2-ethylhexyl phthalate (DOP)
100 parts by weight (tensile modulus of plasticized vinyl chloride resin 30 kg/
cm ² ) Lead-based stabilizer 3 parts by weight Lead-based lubricant 1.5 parts by weight Nickel fine particles (apparent density 0.8 g/cm ³ , specific surface area 0.58 m ² /g, average particle diameter 3 μ) 650 parts by weight (30 vol%) Method described below When the resistance of the sheet was measured by 50×10 ⁶ Ω (50 MΩ or more), the resistance of the sheet was 50 × 10 6 Ω (50 MΩ or more). For a layer (1050, 0.1 mm thick) extruded and laminated, we measured the change in surface resistance over time.The results are shown in Figure 1.The measurement method was a test of 150 mm long and 20 mm wide from the sheet. Cut out a piece, and leave 25 mm on both sides of the surface (the side that is not covered with adhesive, etc.) in the center.
The resistance between 100mm was measured. In the figure, the horizontal axis shows elapsed time (hr), and the vertical axis shows the logarithm of volume resistivity (Ω cm) (the same applies to the following drawings). 1 shows the resistance curve of tape attachment, and 2 shows the resistance curve of lamination. As is clear from the drawings, the resistance of the sheets with adhesive tape attached to the back and the laminated sheets drops to about 10 ² (about 10 ⁰ in terms of volume resistivity) in a short period of time, and the resistance decreases over time. is about 10 ¹ to 10 ⁰ (volume resistivity is about 10 ^-1 to
10 ^-2 ), indicating that conductivity is imparted. On the other hand, in the case of a sheet that is not adhered with an adhesive or the like, the resistance does not decrease over time, but rather shows a tendency for the resistance to increase over time (not shown). Example 2 The same ingredients as Example 1 except for the vinyl chloride resin,
The mixtures were hot-dry blended according to the following six formulations (expressed in parts by weight), heated and kneaded using mill rolls, and sheets with a thickness of 0.3 mm and a sheet of 0.7 mm were formed. The resistance was all 50MΩ or more. Adhesive tape was attached to the back surface of these sheets in the same manner as in Example 1, and the change in resistance over time was measured, and the results shown in FIGS. 2 and 3 were obtained.

[Table] Figures 2 and 3 are graphs of 0.3mm and 0.7mm sheets, respectively.
7 and 8 are experiment Nos. 1, 2, 3, 4, and 5, respectively.
and 6 resistance curves are shown. The flexibility of the molded product, i.e. the amount of plasticizer, is 50~
Even if the nickel content is varied within the range of 200 PHR, the nickel content is varied within the range of 25 to 35 vol%, or the thickness is different from 0.3 mm to 0.7 mm, the resistance decreases to the same degree. Is recognized. Example 3 Commercially available adhesive tapes A (manufactured by Nitto Denko Corporation) and B (manufactured by Sumitomo 3M) were attached to the same sheet as used in Example 1 in the same manner as in Example 1, and the resistance over time was measured. The changes were measured and the results shown in FIG. 4 were obtained. Although the composition of the adhesive is unknown, it is clear that even commercially available non-conductive adhesive tapes have the effect of imparting conductivity.

[Brief explanation of drawings]

1 to 4 are graphs showing the state of conductivity imparted by the method of the present invention, in which the horizontal axis represents the elapsed time, and the vertical axis represents the logarithm of the volume resistivity.

Claims (1)

[Scope of Claims] 1. A method for imparting conductivity to the surface of a molded article having two surfaces, obtained from a pressure-sensitive resin composition containing a thermoplastic resin and metal fine particles as main components, wherein the back surface of the molded article is provided with electrical conductivity. A method for imparting conductivity to a pressure-sensitive resin composition molded article, which comprises closely adhering a non-conductive adhesive, glue, or thermoplastic resin. 2. A method for imparting conductivity to a pressure-sensitive resin composition molded article according to claim 1, wherein the molded article is a film or a sheet. 3. A method for imparting conductivity to a pressure-sensitive resin composition molded article according to claim 1, wherein the content of metal fine particles is in the range of 10 to 40% by volume of the resin composition. 4. A method for imparting electrical conductivity to a pressure-sensitive resin composition molded article according to claim 1 or 3, wherein the metal fine particles have an average particle diameter in the range of 0.1 to 40μ. 5 The thermoplastic resin constituting the pressure-sensitive resin composition has a tensile modulus of 2×10 ⁴ Kg/cm ² or less, or is made to have the same value or less, as measured in accordance with JIS K6301. A method for imparting electrical conductivity to a pressure-sensitive resin composition molded article according to claim 1.