JP6979388B2 - Manufacturing method of antistatic molded product - Google Patents

Description

The present invention relates to a method for manufacturing an antistatic molded product.

Patent Document 1 introduces kneading conductive powders such as carbon black such as Ketjen black as a method for imparting antistatic properties to polybutylene terephthalate resin, polyamide resin and the like.

However, these conductive powders are required to have further antistatic properties.

Japanese Unexamined Patent Publication No. 09-048909

An object of the present invention is to provide a method for producing an antistatic molded product having particularly excellent antistatic properties.

In the process of research in which it is an object of the present invention to provide a method for producing an antistatic molded product having particularly excellent antistatic properties, the present inventor has a carbon having a dibutyl phthalate oil absorption of 300 ml / 100 g or more per 100 parts by mass of a resin. As a result of evaluating the resin composition containing 4.8 to 9.0 parts by mass of black by changing the injection rate, a correlation was found between the shear rate and the volume resistance, and the shear rate during injection molding was 30 / sec. As described above, it has been found that the above-mentioned problems can be solved by setting the content to 500 / sec or less, and the present invention has been completed.

That is, the present invention relates to the following (1) to (5).
(1) A resin composition containing 4.8 to 9.0 parts by mass of carbon black having a dibutyl phthalate oil absorption of 300 ml / 100 g or more with respect to 100 parts by mass of the resin at a shear rate of 30 / sec or more and 500 / sec or less. A method for manufacturing an antistatic molded product, which comprises injection molding.
(2) The method for manufacturing an antistatic molded product according to (1), wherein the volume resistivity of the antistatic molded product ^{is less than 1.0 × 10 14 Ω · cm.}
(3) The method for producing an antistatic molded product according to (1) or (2), wherein the resin is a thermoplastic resin.
(4) The antistatic molded product according to (3), wherein the thermoplastic resin is a resin selected from the group consisting of polybutylene terephthalate resin, polyacetal resin, polyphenylene sulfide resin, liquid crystal polymer resin, and cyclic olefin resin. Production method.
(5) A method for improving the antistatic property of a molded product by using the method for manufacturing an antistatic molded product according to any one of (1) to (4).

According to the present invention, it is possible to provide a method for manufacturing an antistatic molded product having particularly excellent antistatic properties.

It is a figure which shows the relationship between the shear rate and the volume resistivity obtained in this invention.

Hereinafter, one embodiment of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be carried out with appropriate modifications as long as the effects of the present invention are not impaired.

[Manufacturing method of antistatic molded product]
Hereinafter, details of the method for manufacturing the antistatic molded product of the present embodiment will be illustrated and described.

The method for producing an antistatic molded product of the present invention is characterized in that the shear rate during injection molding is 30 / sec or more and 500 / sec or less. By setting the shear rate during injection molding within this range, the volume resistivity of the antistatic molded product to be manufactured can be lowered and the antistatic property can be made excellent. The shear rate during injection molding is preferably 50 / sec or more and 400 / sec or less, more preferably 60 / sec or more and 300 / sec or less, and 70 / sec or more and 250 / sec or less. Is more preferable, and 80 / sec or more and 200 / sec or less are particularly preferable. The shear rate of the present invention can be calculated, for example, by the following formula (1) from the inflow rate calculated from the injection speed of the molding machine and the cylinder diameter, and the width and thickness of the molded product. The following is an equation when the cross section of the molded product is rectangular, and in the case of other shapes, it may be appropriately calculated by a known method.

Shear rate [/ sec] = 6 x inflow flow rate [mm ³ / sec] ÷ (width [mm] x thickness [mm] ² ) ... (1)

The volume resistivity of the antistatic molded product manufactured by the method for manufacturing the antistatic molded product of the present invention varies depending on the final application, but is 1.0 × 10 ¹⁴ Ω in terms of antistatic property. It is preferably less than cm, more preferably 1.0 × 10 ¹³ Ω · cm or less, and even more preferably 1.0 × 10 ¹² Ω · cm or less. On the other hand, in terms of insulation, ^{it is preferably 1.0 × 10 7} Ω · cm or more, more preferably 1.0 × 10 ⁸ Ω · cm or more, and 1.0 × 10 ⁹ Ω · cm or more. Is more preferable. When the value of the volume resistivity is in the above range, it is possible to obtain an antistatic molded product having excellent antistatic properties.

[Thermoplastic resin]
The antistatic molded product produced by the method for producing an antistatic molded product of the present invention is preferably made of a thermoplastic resin. Examples of the thermoplastic resin include polybutylene terephthalate resin, polyacetal resin, polyphenylene sulfide resin, liquid crystal polymer resin, and cyclic olefin copolymer resin. Hereinafter, they will be described in sequence.

(Polybutylene terephthalate resin)
The polybutylene terephthalate resin contains a dicarboxylic acid component containing at least terephthalic acid or an ester-forming derivative thereof ( _{such as an alkyl ester of C 1-6} or an acid halide) and an alkylene glycol having at least 4 carbon atoms (1,4-butane). It is a polybutylene terephthalate resin obtained by polycondensing with a glycol component containing a diol) or an ester-forming derivative thereof (acetylated product or the like). In the present embodiment, the polybutylene terephthalate resin is not limited to the homopolybutylene terephthalate resin, and may be a copolymer containing 60 mol% or more of the butylene terephthalate unit.

The amount of the terminal carboxyl group of the polybutylene terephthalate resin is not particularly limited as long as it does not impair the object of the present invention, but is preferably 30 meq / kg or less, and more preferably 25 meq / kg or less.

The intrinsic viscosity of the polybutylene terephthalate resin is not particularly limited as long as it does not impair the object of the present invention, but is preferably 0.60 dL / g or more and 1.2 dL / g or less, and 0.65 dL / g or more and 0.9 dL / g. It is more preferably g or less. When a polybutylene terephthalate resin having an intrinsic viscosity in such a range is used, the obtained polybutylene terephthalate resin composition is particularly excellent in moldability. It is also possible to adjust the intrinsic viscosity by blending polybutylene terephthalate resins having different intrinsic viscosities. For example, a polybutylene terephthalate resin having an intrinsic viscosity of 0.9 dL / g can be prepared by blending a polybutylene terephthalate resin having an intrinsic viscosity of 1.0 dL / g and a polybutylene terephthalate resin having an intrinsic viscosity of 0.7 dL / g. Can be done. The intrinsic viscosity of the polybutylene terephthalate resin can be measured, for example, in o-chlorophenol under the condition of a temperature of 35 ° C.

When an aromatic dicarboxylic acid other than terephthalic acid or an ester-forming derivative thereof is used as a comonomer component in the preparation of a polybutylene terephthalate resin, for example, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'- _{C 8-14} aromatic dicarboxylic acid such as dicarboxydiphenyl ether _{; C 4-16} alcandicarboxylic acid such as succinic acid, adipic acid, azelaic acid, sebacic _{acid; C 5-10} cycloalcandicarboxylic acid such as cyclohexanedicarboxylic acid. Acid; An ester-forming derivative of these dicarboxylic acid components (C _1-6 alkyl ester derivative, acid halide, etc.) can be used. These dicarboxylic acid components can be used alone or in combination of two or more.

Among these dicarboxylic acid components, C _{8-12 aromatic dicarboxylic acids such as isophthalic acid and C 6-12} alcandicarboxylic acids such as adipic acid, azelaic acid and sebacic acid are more preferable.

When a glycol component other than 1,4-butanediol is used as the comonomer component in the preparation of the polybutylene terephthalate resin, for example, ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, hexamethylene glycol, neopentyl _{C 2-10} alkylene glycols such as glycols and 1,3-octanediols; polyoxyalkylene glycols such as diethylene glycols, triethylene glycols and dipropylene glycols; alicyclic diols such as cyclohexanedimethanol and hydride bisphenol A; bisphenols _{Aromatic diols such as A, 4,4'-dihydroxybiphenyl; C 2-4} alkylene oxide adducts of bisphenol A such as ethylene oxide 2 mol adducts of bisphenol A and propylene oxide 3 mol adducts of bisphenol A; Alternatively, ester-forming derivatives of these glycols (acetylated products, etc.) can be used. These glycol components can be used alone or in combination of two or more.

_{Among these glycol components, C 2-6} alkylene glycols such as ethylene glycol and trimethylene glycol, polyoxyalkylene glycols such as diethylene glycol, and alicyclic diols such as cyclohexanedimethanol are more preferable.

Examples of the comonomer component that can be used in addition to the dicarboxylic acid component and the glycol component include 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 4-carboxy-4'-hydroxybiphenyl and the like. Aromatic hydroxycarboxylic acids; aliphatic hydroxycarboxylic acids such as glycolic acid and hydroxycaproic acid; C _3-12 lactones such as propiolactone, butyrolactone, valerolactone, caprolactone (ε-caprolactone etc.); esters of these comonomer components Examples thereof include formable derivatives (C _1-6 alkyl ester derivatives, acid halides, acetylates, etc.).

The content of the polybutylene terephthalate resin is preferably 30 to 90% by mass, more preferably 40 to 80% by mass, still more preferably 50 to 70% by mass, based on the total mass of the resin composition. ..

(Polyacetal resin)
The polyacetal resin is _{a polymer compound having an oximethylene group (-CH 2} O-) as a main constituent unit, and has a polyoxymethylene homopolymer or an oximethylene group as a main repeating unit, and other constituent units, for example, It may be any of a copolymer containing a small amount of a comonomer unit such as ethylene oxide, 1,3-dioxolane and 1,4-butanediol formal, a terpolymer, and a block polymer. Further, the polyacetal resin may be one in which the molecule is not only linear but also has a branched or crosslinked structure, or may be a known modified polyoxymethylene into which another organic group is introduced. Further, the polyacetal resin is not particularly limited in terms of the degree of polymerization, and has melt molding processability (for example, a melt flow value (MFR) of 1.0 g / 10 minutes or more under a load of 190 ° C. and 2160 g / 100 g / It may be 10 minutes or less).

(Polyphenylene sulfide resin)
The polyphenylene sulfide resin is a polymer containing 70 mol% or more, preferably 80 mol% or more of the repeating units represented by the structural formula (-paraphenylene group-S-). Further, as the repeating unit having a structure other than the structural formula (-paraphenylene group-S-), (-m-phenylene group-S-), (-o-phenylene group-S-), (-alkyl group or Phenylene group-S-) substituted with phenyl group, (-p, p'-biphenylene group-S-), (p, p'-diphenylene ether group-S-), (-p, p'-di Phenylene carbonyl group-S-), (-naphthalene group-S-) and the like can be used.

(Liquid crystal polymer resin)
The liquid crystal polymer refers to a melt-processable polymer having a property of forming an optically anisotropic molten phase. The properties of the anisotropic molten phase can be confirmed by a conventional polarization inspection method using an orthogonal polarizing element. More specifically, the confirmation of the anisotropic molten phase can be carried out by observing the molten sample placed on the Leitz hot stage at a magnification of 40 times under a nitrogen atmosphere using a Leitz polarizing microscope.
The liquid crystal polymer applicable to the present invention normally transmits polarized light and exhibits optical anisotropy when inspected between orthogonal polarizing elements, even in the molten rest state.

The liquidaceous polymer used in the present invention is preferably a total aromatic polyester or a total aromatic polyester amide, which have a logarithmic viscosity (IV) when dissolved in pentafluorophenol at 60 ° C. at a concentration of 0.1% by weight. ) Is preferably about 2.0 dl / g or more, and more preferably 2.0 to 10.0 dl / g.

The total aromatic polyester or the total aromatic polyester amide is particularly preferably an aromatic having at least one compound selected from the group of aromatic hydroxycarboxylic acid, aromatic hydroxyamine, and aromatic diamine as a constituent component. It is a group polyester or an aromatic polyester amide.

(Cyclic olefin resin)
The cyclic olefin resin is a polymer compound having a carbon-carbon bond in the main chain and having a cyclic hydrocarbon structure in at least a part of the main chain. This cyclic hydrocarbon structure is introduced by using a compound (cyclic olefin) having at least one olefinic double bond in the cyclic hydrocarbon structure as a monomer, such as norbornene and tetracyclododecene. Will be done.

The cyclic olefin resin includes an addition (co) polymer of a cyclic olefin or a hydrogenated product thereof (1), an addition copolymer of a cyclic olefin and an α-olefin or a hydrogenated product thereof (2), and a ring opening of the cyclic olefin (co). ) A polymer or a hydrogenated product thereof (3).

Specific examples of the cyclic olefin include cyclopentene, cyclohexene, cyclooctene; one-ring cyclic olefin such as cyclopentadiene and 1,3-cyclohexadiene; bicyclo [2.2.1] hepta-2-ene (common name: norbornene). ), 5-Methyl-bicyclo [2.2.1] hepta-2-ene, 5,5-dimethyl-bicyclo [2.2.1] hepta-2-ene, 5-ethyl-bicyclo [2.2. 1] Hepta-2-ene, 5-butyl-bicyclo [2.2.1] hepta-2-ene, 5-ethylidene-bicyclo [2.2.1] hepta-2-ene, 5-hexyl-bicyclo [ 2.2.1] Hepta-2-ene, 5-octyl-bicyclo [2.2.1] hepta-2-ene, 5-octadecyl-bicyclo [2.2.1] hepta-2-ene, 5- Methylidene-bicyclo [2.2.1] hepta-2-ene, 5-vinyl-bicyclo [2.2.1] hepta-2-ene, 5-propenyl-bicyclo [2.2.1] hepta-2- Two-ring cyclic olefins such as ene; tricyclo [4.3.0.12.5] deca-3,7-diene (common name: dicyclopentadiene), tricyclo [4.3.0.12.5] deca -3-ene; tricyclo [4.4.0.12,5] undeca-3,7-diene or tricyclo [4.4.0.12,5] undeca-3,8-diene or partial hydrogenation thereof Tricyclo [4.4.0.12,5] undeca-3-ene; 5-cyclopentyl-bicyclo [2.2.1] hepta-2-ene, which is a substance (or an adduct of cyclopentadiene and cyclohexene), 5 -Cyclohexyl-bicyclo [2.2.1] hepta-2-ene, 5-cyclohexenylbicyclo [2.2.1] hepta-2-ene, 5-phenyl-bicyclo [2.2.1] hepta-2 Tricyclic olefins such as −ene; tetracyclo [4.4.0.12,5.17,10] dodeca-3-ene (also simply referred to as tetracyclododecene), 8-methyltetracyclo [4.4. 0.12,5.17,10] dodeca-3-ene, 8-ethyltetracyclo [4.4.0.12,5.17,10] dodeca-3-ene, 8-methylidenetetracyclo [4] 4.0.12,5.17,10] dodeca-3-ene, 8-ethylidenetetracyclo [4.4.0.12,5.17,10] dodeca-3-ene, 8-vinyltetracyclo [4,4.0.12,5.17,10] Dodeca-3-ene, 8-prope Nyl-tetracyclo [4.4.0.12,5.17,10] 4-ring cyclic olefin such as dodeca-3-ene; 8-cyclopentyl-tetracyclo [4.4.0.12,5.17,10] Dodeca-3-ene, 8-cyclohexyl-tetracyclo [4.4.0.12,5.17,10] Dodeca-3-ene, 8-cyclohexenyl-tetracyclo [4.4.0.12,5.17] , 10] dodeca-3-ene, 8-phenyl-cyclopentyl-tetracyclo [4.4.0.12,5.17,10] dodeca-3-ene; tetracyclo [7.4.13,6.01,9] .02,7] Tetradeca-4,9,11,13-tetraene (also called 1,4-methano-1,4,4a, 9a-tetrahydrofluorene), tetracyclo [8.4.14, 7.01, 10] .03,8] Pentadeca-5,10,12,14-tetraene (also referred to as 1,4-methano-1,4,4a, 5,10,10a-hexahydroanthracene); pentacyclo [6.6.1 .13,6.02,7.09,14] -4-hexadecene, pentacyclo [6.5.1.13,6.02,7.09,13] -4-pentadecene, pentacyclo [7.4.0 .02, 7.13, 6.110, 13] -4-pentadecene; heptacyclo [8.7.0.12, 9.14, 7.111, 17.03, 8.012, 16] -5-eikosen , Heptacyclo [8.7.0.12,9.03,8.14,7.012,17.113, l6]-14-eicosene; polycyclic cyclic olefins such as cyclopentadiene tetramers. .. These cyclic olefins can be used alone or in combination of two or more.

Specific examples of the α-olefin copolymerizable with the cyclic olefin include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, 3 -Ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1- The number of carbon atoms of hexene, 3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene and the like is 2 to 20, preferably carbon number. Examples thereof include 2 to 8 ethylenes or α-olefins. These α-olefins can be used alone or in combination of two or more.

The carbon black used in the present invention has a dibutyl phthalate oil absorption amount of 300 ml / 100 g or more, preferably 320 ml / 100 g or more, and more preferably 350 ml / 100 g or more from the viewpoint of improving antistatic properties. It is more preferably 375 ml / 100 g or more, further preferably 380 ml / 100 g or more, and most preferably 390 ml / 100 g or more. On the other hand, from the viewpoint of moldability, the oil absorption of dibutyl phthalate of carbon black is preferably 500 ml / 100 g or less, more preferably 450 ml / 100 g or less, and further preferably 425 ml / 100 g or less. It is more preferably 420 ml / 100 g or less, and most preferably 410 ml / 100 g or less. When the amount of dibutyl phthalate oil absorbed is within the above range, it is possible to provide an antistatic molded product having excellent antistatic properties and moldability.

The amount of carbon black used in the present invention is 4.8 to 9.0 parts by mass, preferably 5.0 to 8.0 parts by mass, and more preferably 5.2 to 8.0 parts by mass with respect to 100 parts by mass of the resin. It is 7.5 parts by mass, more preferably 5.4 to 7.0 parts by mass, and most preferably 5.5 to 6.5 parts by mass. When the amount of carbon black used is in the above range, it is possible to provide an antistatic molded product having both antistatic properties and moldability.

The average primary particle size of the carbon black used in the present invention is not particularly limited, but is preferably 5 to 100 nm, more preferably 20 to 50 nm, and more preferably 30 to 40 nm in order not to impair the mechanical properties. Is more preferable. The average primary particle size in the present invention is an arithmetic average particle size obtained by observing 1000 particles of carbon black before being blended in the resin composition with an electron microscope.

(filler)
If necessary, a filler is used in the method for producing an antistatic molded product of the present invention. Such a filler is preferably blended in order to obtain excellent performance properties such as mechanical strength, heat resistance, dimensional stability, and electrical properties, and is particularly effective for the purpose of increasing rigidity. For this, a fibrous, powdery or plate-like filler is used depending on the purpose.

As the fibrous filler, glass fiber, asbestos fiber, carbon fiber, silica fiber, silica / alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, stainless steel, aluminum, titanium, etc. Examples include metal fibrous materials such as copper and brass. In addition, organic fibrous substances having a high melting point such as polyamide, fluororesin, and acrylic resin can also be used.

Examples of the powder / granular filler include quartz powder, glass beads, glass powder, calcium silicate, aluminum silicate, kaolin, talc, clay, diatomaceous earth, silicates such as wollastonite, and oxidation of metals such as iron oxide, titanium oxide, and alumina. Examples thereof include metal carbonates such as calcium carbonate and magnesium carbonate, sulfates of metals such as calcium sulfate and barium sulfate, silicon carbide, silicon nitride, boron nitride, and various metal powders.

Examples of the plate-shaped inorganic filler include mica, glass flakes, and various metal foils.

The type of filler is not particularly limited, and one or more fillers can be added. In particular, it is preferable to use potassium titanate fiber, mica, talc, and wollastonite.

The amount of the filler added is not particularly specified, but is preferably 200 parts by mass or less with respect to 100 parts by mass of the resin. When the filler is added excessively, the moldability is poor and the toughness is lowered.

(Additive)
Further, in the method for producing an antistatic molded product of the present invention, a known substance generally added to a thermoplastic resin or the like can be added and used in combination in order to impart desired properties. For example, antioxidants, UV absorbers, light stabilizers, stabilizers such as hydrolysis resistance improvers, lubricants, mold release agents, colorants such as dyes and pigments, plasticizers, flame retardants, flame retardant aids, etc. Can also be blended. In particular, the addition of an antioxidant for improving heat resistance is effective. Further, other resins may be added as long as the effects of the present invention are not impaired.

The form of the material used in the method for producing an antistatic molded product of the present invention may be a powder or granular material mixture or a melt mixture (melt kneaded product) such as pellets. The method for producing the antistatic molded product according to the embodiment of the present invention is not particularly limited, and can be produced using equipment and methods known in the art. For example, the required components can be mixed and kneaded using a single-screw or twin-screw extruder or other melt-kneading device to prepare pellets for molding. Multiple extruders or other melt kneaders may be used. Further, all the components may be input from the hopper at the same time, or some components may be input from the side feed port.

Further, the method for manufacturing an antistatic molded product of the present invention is performed by injection molding.

[Method for improving antistatic properties of molded products]
Further, the method for producing an antistatic molded product of the present invention can be used as a method for improving the antistatic property of a molded product.

[Example]
Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded.

(Example 1)
Polybutylene terephthalate resin is weighed and mixed in 100 parts by mass, carbon black (average particle diameter 35 nm, dibutyl phthalate oil absorption amount 396 ml / 100 g) by 6.1 parts by mass, and glass fiber by 45.5 parts by mass. A resin composition was obtained.

100 parts by mass of polybutylene terephthalate resin, 6.1 parts by mass of carbon black (average particle diameter 22 nm, oil absorption of dibutyl phthalate 116 ml / 100 g), 45.5 parts by mass of glass fiber, weighed and mixed, and polybutylene terephthalate. A resin composition was obtained.

Each of the polybutylene terephthalate resin compositions obtained above was injection-molded with an injection molding machine at a cylinder temperature of 270 ° C., a mold temperature of 60 ° C., and a holding pressure of 60 MPa to obtain a flat plate-shaped test piece of 80 mm × 80 mm × 3 mm. rice field. In addition, the injection speed was changed so as to be the shear rate shown in Table 1. The volume resistivity of the test piece obtained according to IEC60093 was measured. The results are shown in Table 1 and FIG.

As shown in Table 1 and FIG. 1, when the polybutylene terephthalate resin composition of Example (◆) was injection-molded at a low shear rate, a molded product having a low volume resistivity and excellent antistatic properties could be obtained. rice field.

Claims (2)

A resin composition containing 4.8 to 9.0 parts by mass of carbon black having a dibutyl phthalate oil absorption of 300 ml / 100 g or more with respect to 100 parts by mass of a thermoplastic resin containing at least polybutylene terephthalate resin is prepared at a shear rate of 30 / sec. As described above, the manufacture of an antistatic molded product obtained by injection molding at 500 / sec or less and having a volume resistance of 1.0 × 10 ⁷ Ω · cm or more ^{and less than 1.0 × 10 14} Ω · cm. Method. A method for improving the antistatic property of a molded product by using the method for manufacturing an antistatic molded product according to claim 1.