JP2003261715A - Rubber composition and resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition and a resin composition capable of obtaining a molded article having good dispersibility of carbon black, excellent surface smoothness, and excellent resistance stability. SOLUTION: The amount of silica impregnated is 0.1 to 20% by weight, the amount of surfactant impregnated is 0.1 to 10% by weight, and the aggregate size distribution D _1/2 / D _st is 0.65 to 1.1. A rubber composition and a resin composition comprising a surfactant-containing silica surface-treated carbon black.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber composition and a resin composition containing carbon black, and in particular, the dispersibility of carbon black is good, and the surface of the obtained molded product is smooth and the resistance is low. The present invention relates to a rubber composition and a resin composition having excellent stability.

[0002]

2. Description of the Related Art Trays, cassettes, cases, jigs for assembling, etc., when handling electronic devices such as ICs, wafers, hard disks, magnetic heads, liquid crystal devices, etc. for assembling and carrying advanced electronic devices. Antistatic parts, components of equipment equipped with these devices, or molding materials such as photoconductors for copiers, printers, semi-conductive members such as intermediate transfer belts, paper transfer transfer belts, and intermediate transfer drums. In some cases, a rubber composition or a resin composition containing carbon black is used for the purpose of imparting antistatic property or conductivity.

[0003]

A molded product obtained by molding a conventional rubber composition or resin composition containing carbon black has a large variation in resistance value, that is, the electrical resistance varies depending on the location of the molded product. There was a problem that the resistance values were different and were not uniform. There is also a problem that the surface smoothness of the molded product is poor and the surface roughness is high. The cause of such variations in the resistance value of the molded product and the surface roughness is that the carbon black compounded in the composition is unevenly dispersed.

The present invention solves the above-mentioned conventional problems and provides a rubber composition and a resin composition which have good dispersibility of carbon black, have a smooth surface of the resulting molded article and are excellent in resistance stability. The purpose is to provide.

[0005]

The rubber composition of the present invention comprises:
In a rubber composition containing carbon black, the carbon black has a silica loading of 0.1 to 20% by weight.
And the amount of the surfactant impregnated is 0.1 to 10% by weight, and the aggregate size distribution D _1/2 / D _st is 0.6.
It is characterized in that it is a surface-active silica surface-treated carbon black of 5 to 1.1.

The resin composition of the present invention is a resin composition containing carbon black, wherein the carbon black has a silica loading of 0.1 to 20% by weight and a surfactant loading of 0.1 to. It is 10% by weight, and is a surfactant-containing silica surface-treated carbon black having an aggregate size distribution D _1/2 / D _st of 0.65 to 1.1.

The carbon black used in the present invention is a surfactant-containing silica surface-treated carbon black treated with silica and a surfactant. This carbon black has the following effects due to the addition of silica and a surfactant.

(1) Effect of Silica By adhering silica having a large electric resistance to the surface of the conductive carbon black, the dispersion of the electric resistance when compounded with rubber or resin becomes small and stabilized.
In addition, the change in electric resistance with respect to the amount of carbon black compounded becomes small.

In particular, when blended with a polar polymer such as nitrile rubber (NBR), if silica having polar silanol groups adheres to the surface, the compatibility between the rubber or resin and the carbon black is improved. , The dispersed state becomes good.

(2) Effect of Surfactant The dispersion of the carbon black impregnated with silica becomes good. Further, because of that, variations in electric resistance are also reduced.

Aggregate size distribution D _1/2 / D _st
The carbon black having a particle size distribution of 0.65 to 1.1 has a relatively wide aggregate size distribution, and the carbon black having such a wide aggregate size distribution has the same compounding amount as that of the carbon black having a uniform size. In this case, the distance between the particles of the rubber or resin in the matrix becomes large, which has the effect of increasing the electrical resistance of the carbon black compounded rubber or resin and stabilizing it.

The aggregate size distribution D _1/2 /
D _st is an index showing the distribution of aggregate diameters, and is determined by the centrifugal sedimentation method as follows.

Using a "BI-DCP" particle cider manufactured by Brookhaven Co., carbon black was first precisely weighed to a carbon black concentration of 0.01% by weight and then sufficiently dispersed by ultrasonic waves to obtain a sample. To do. BI-
The rotation speed of the DCP was set to 6000 rpm, the sample solution (0.25 to 1.00 ml) was injected into 30 ml of the spin solution, and centrifugal sedimentation was simultaneously started.
Create an aggregate size distribution curve as shown in. Half-width D
_½ and the mode value D _st are obtained from this aggregate diameter distribution curve, and the aggregate size distribution D _1/2 / D _st is calculated. In FIG. 1, the broken line portion has the same length, and the half width is the length of the solid line portion.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the rubber composition and the resin composition of the present invention will be described in detail below.

First, the surfactant-containing silica surface-treated carbon black used in the present invention will be described.

The surfactant-containing silica surface-treated carbon black used in the present invention has a silica loading of 0.1 to 20.
% By weight, the amount of surfactant impregnated is 0.1 to 10% by weight, and the aggregate size distribution D _1/2 / D _st is 0.65.
1.1.

Such surface-active agent-containing silica surface-treated carbon black is obtained by, for example, using a granulation water obtained by emulsifying and dispersing a silicon compound with a surface-active agent to produce a non-granulated product of carbon black by laboratory granulation. It can be manufactured by wet granulation with a granulating device such as a device.

The silicon compound used here is a silane in which all organic groups are bonded to silicon via oxygen and /
Alternatively, polysiloxane is preferable. The silane and / or polysiloxane in which all the organic groups are bonded to silicon via oxygen means that hydrogen, an alkyl group, a vinyl group, a phenyl group or another functional group is bonded to Si via O. Existing silane and / or (Si-O) _n as a main chain (the main chain may be branched or may form a ring), and hydrogen, an alkyl group, a vinyl group, or a phenyl group are added to Si through O. A polysiloxane having a group or other functional group bonded thereto, preferably a tetraalkoxysilane and / or a polyalkoxypolysiloxane in which an alkoxy group having 1 to 4 carbon atoms is bonded to Si is used. The latter can be easily obtained as the low condensation product of the former. Examples of the latter include those represented by the following general formula (I). (RO) ₃ -Si-O- [Si (OR) _n- O _(3-n) ] _mR .. (I)

Here, n = 1 or 2, m is an integer of 0 or more,
R is an alkyl group having 1 to 4 carbon atoms which may be different from each other. This alkyl group may be replaced by hydrogen. Particularly, when R is a methyl group, there is an oligomer which is a low condensate of tetramethoxysilane, and "MKC Silicate MS51" manufactured by Mitsubishi Chemical Corporation contains 1% by weight of a monomer (that is, tetramethoxysilane). It is preferable since it is less than the following, and therefore it is excellent in quality stability and is less toxic by the monomer and safe in use. In the present invention, such a silane and / or polysiloxane in which all the organic groups are bonded to silicon through oxygen can be used as they are, but water and a hydrolysis catalyst are added thereto. Alternatively, a hydrolyzed condensate obtained by further condensing a hydrolyzed product or a hydrolyzed product may be used.

Examples of the hydrolytic condensate include "MKC silicate MS51SG1" (manufactured by Mitsubishi Chemical Co., Ltd.) obtained by hydrolytically condensing the above tetramethoxysilane oligomer in alcohol. This product has a large number of silanol groups formed by hydrolysis and is preferably used. Since these tetraalkoxysilanes and / or polyalkoxypolysiloxanes have a large number of alkoxy groups, the adhesion to carbon black and the production of silanol groups are extremely good, and the obtained surface-treated carbon black and the mixture thereof are used. It is considered that the properties of the rubber composition and the resin composition are greatly improved.

The alkoxy groups contained in these tetraalkoxysilanes and / or polyalkoxypolysiloxanes can be appropriately modified with other organic groups by transesterification or other means. Specifically, a desired organic group may be introduced with various active hydrogen-containing compounds or the like, for example, by reacting with an alcohol having a longer chain organic group to introduce a longer chain organic group. Alternatively, silane and / or polysiloxane in which all of these organic groups are bonded to silicon via oxygen may be mixed with another organic component such as a silane coupling agent, and the carbon black may be brought into contact therewith. In this case, the amount of the other organic component is 50 parts by weight or less, preferably 20 parts by weight or less based on 100 parts by weight of silane and / or polysiloxane in which all organic groups are bonded to silicon through oxygen. Examples of the organic component include various silane coupling agents, various resin components, and the like.
It may be appropriately selected as necessary and blended with the silane and / or polysiloxane.

On the other hand, as the surface active agent, nonionic surface active agents, anionic surface active agents, cationic surface active agents, amphoteric surface active agents and the like can be used, but nonionic surface active agents are preferable. . Examples of nonionic surfactants include polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, polyoxyethylene derivative, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester, and polyoxyethylene curing agent. Castor oil, polyoxyethylene alkylamine, alkylalkanolamide, etc. can be used.

These silicon compounds and surface active agents are appropriately used so that the amount of them to be attached to carbon black is within the above range.

When the silica-impregnated amount of the surfactant-containing silica surface-treated carbon black used in the present invention (impregnated amount of silicon compound converted to silica (SiO ₂ )) is less than 0.1% by weight, the silica-impregnated amount is too small and the silica is too small. It is not possible to sufficiently obtain the above-mentioned effect due to the attachment of When the amount of silica impregnated exceeds 20% by weight, the excessive silica becomes an adhesive between the carbon blacks, and the dispersion of the silica-impregnated carbon black deteriorates, which is not preferable.

Further, if the amount of the surfactant added is less than 0.1% by weight, the amount of the surfactant added is too small to sufficiently obtain the above-mentioned effects due to the addition of the surfactant, and When the amount of the agent impregnated exceeds 10% by weight, the characteristics as an impurity become conspicuous, which is not preferable.

The silica loading and the surfactant loading are the silica equivalent weight of the silicon compound attached to the carbon black and the surfactant weight relative to the weight of the carbon black, respectively.

When the carbon black is wet-granulated using the granulation water obtained by emulsifying and dispersing the above-mentioned silicon compound with a surfactant, the treatment temperature is preferably 200 ° C. or lower, particularly 20 to 80 ° C. With such a treatment temperature, a part of the organic group bonded to silicon is hydrolyzed through oxygen in the drying step after granulation, and a silanol group is generated on the carbon black surface.

In order to obtain a carbon black having an aggregate size distribution D _1/2 / D _st of 0.65 to 1.1 by such a granulation treatment, the distribution of the carbon black before the surface treatment is preliminarily performed. D _1/2 / D _st is 0.65
What was manufactured so as to be 1.1 may be used.

The nitrogen specific surface area (N ₂ specific surface area) and DBP absorption of the carbon black used in the present invention are not particularly limited, but the nitrogen specific surface area is 20 to 250 m ² /
g, the DBP absorption amount is preferably about 50 to 180 ml / 100 g.

The rubber composition and resin composition of the present invention are prepared by blending such a surfactant-containing silica surface-treated carbon black with a rubber or a resin.

The ratio of the surfactant-containing silica surface-treated carbon black in the rubber composition and the resin composition is appropriately determined according to the desired antistatic property or conductivity, but in the usual case, the rubber as the main component is used. Alternatively, it is in the range of 30 to 70% by weight with respect to the resin. If the blending amount of the surfactant-containing silica surface-treated carbon black is less than this range, sufficient antistatic property or conductivity cannot be obtained, and if the blending amount is too large, the processability and moldability are impaired. There is.

As the rubber component of the rubber composition of the present invention,
One or more kinds of natural rubber, butyl rubber, nitrile rubber, polyisoprene rubber, polybutadiene rubber, silicone rubber, styrene-butadiene rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber, chloroprene rubber, acrylic rubber and the like can be mentioned. . These rubbers include carbon black, vulcanizing agent, vulcanizing aid,
A softening agent and other additives are added, and kneading and vulcanization molding are performed according to a conventional method.

As the resin component of the resin composition of the present invention, polypropylene, polyethylene, (high density, medium density, low density, linear low density), propylene ethylene block or random copolymer, polybutadiene, poly Isobutylene, polyamide, polyacetal, polyarylate, polycarbonate, polyphenylene ether, modified polyphenylene ether, polyimide, liquid crystalline polyester, polysulfone, polyether sulfone, polyphenylene sulfite, polybisamide triazole, polyetherimide, polyether ether ketone, polybutylene Terephthalate, polyethylene terephthalate, polyvinyl fluoride, polyvinylidene fluoride,
Ethylene tetrafluoroethylene copolymer, chlorotrifluoroethylene, hexafluoropropylene, perfluoroalkyl vinyl ether copolymer, acrylic, acrylic acid, alkyl ester copolymer, polyester ester copolymer, polyether ester copolymer, poly Examples thereof include thermoplastic resins such as ether amide copolymer and polyurethane copolymer, and thermosetting resins such as epoxy, polyimide, polyamide imide, polymellitic imide, melamine, phenol and unsaturated polyester.

These thermoplastic resins and thermosetting resins are
One kind may be used alone, or two or more kinds may be mixed and used.

These resins may include calcium carbonate, talc, mica, silica, alumina, aluminum hydroxide, magnesium hydroxide, barium sulfate, zinc oxide, zeolite, wollastonite, diatomaceous earth, if necessary.
Glass beads, bentonite, montmorillonite, asbestos, hollow glass spheres, graphite, molybdenum disulfide, titanium oxide, aluminum fiber, stainless steel fiber, brass fiber, aluminum powder, wood powder, chaff, graphite, metal powder, conductive metal oxide Substances, organometallic compounds, fillers such as organometallic salts, antioxidants (phenolic, sulfur-based, etc.), lubricants, various organic / inorganic pigments, ultraviolet absorbers, antistatic agents, dispersants, neutralizing agents , A foaming agent, a plasticizer, a copper damage inhibitor, a cross-linking agent, a flowability improver and the like are added, and if desired, a single screw extruder, a twin screw extruder, a Banbury mixer, a roll, a Brabender, a plastograph, a kneader After kneading and pelletizing using a normal kneader such as
It is made into a molded product by a method such as injection molding.

Since the rubber composition and the resin composition of the present invention have good surface properties of the obtained molded product, and have small variations in electric resistance and excellent resistance stability, they are used for assembling and transporting advanced electronic devices. Components, such as ICs, wafers, hard disks, magnetic heads, liquid crystal devices, and other electronic devices, antistatic components such as trays, cassettes, cases, jigs and tools for assembly, and equipment equipped with these devices. Components, or copiers,
It is industrially very useful as a molding material for a photoconductor of a printer, an intermediate transfer belt, a paper conveyance transfer belt, an intermediate transfer drum, a semiconductive member such as a conductive roll, and the like.

[0037]

EXAMPLES The present invention will be described more specifically with reference to production examples, examples and comparative examples below.

Production Example 1: Surface Treatment of Carbon Black Using carbon black having a nitrogen specific surface area (N ₂ specific surface area) and a DBP absorption amount shown in Table 1, surface treatment was performed as follows, and Carbon blacks B to G having the aggregate size distribution shown in Table 1 were prepared with the silica loadings and surfactant loadings shown. In addition, carbon black A
Was not surface-treated, and carbon black G was prepared by adhering only silica without using a surfactant.

Put carbon black in the lab granulator,
Oligomer that is a low condensate of tetramethoxysilane (trade name: "MKC Silicate MS51", Mitsubishi Chemical Corporation)
A predetermined amount of (manufactured by Kao Corporation) was emulsified with a nonionic surfactant (trade name: "Emulgen 920" manufactured by Kao Corporation) and added together with water. After closing the lid of the lab granulator and performing high speed stirring granulation at 60 ° C. for 1 minute, the granulated product was dried with a dryer.

[0040]

[Table 1]

Examples 1 to 5 and Comparative Examples 1 to 3: Application to rubber composition NBR (nitrile rubber) with 2 parts of carbon black shown in Table 2
A rubber composition in which 2% by weight was kneaded was prepared, and this was crosslinked to prepare a vulcanized rubber press sheet. Similarly, a press sheet of vulcanized rubber in which 25% by weight of carbon black was kneaded was prepared. In Example 5, 1% by weight of a silane coupling agent “Si69” (manufactured by Degussa) was further kneaded. The volume resistivity of the obtained vulcanized press sheet was measured by the following method, and the quality of the sheet surface (surface smoothness) was observed, and the results are shown in Table 2.

[Measurement Method of Volume Resistivity] The thickness is 1.00 ± 0.1 according to JIS plastic electric resistance measurement method.
A 5 mm smooth sheet was used as a test piece, the thickness was measured at room temperature, a direct current of 500 V was applied to this, the volume resistivity was calculated from the current value after charging for 1 minute, and the average value of the measurement results of 5 sheets was calculated. Then, the variation (standard deviation of 5 sheets / average value) was determined.

[0043]

[Table 2]

The following is clear from Table 2.

That is, the electric resistance tends to increase as the amount of carbon black added to silica increases, and the electric resistance decreases as the amount of carbon black compounded increases. Further, the variation in the electric resistance is larger in the sheet having a high electric resistivity region because the blending amount of carbon black is small.

In Comparative Example 1 in which the carbon black not surface-treated was blended, the electric resistance varied greatly. In Comparative Example 2 in which the amount of carbon black attached to silica is large, the dispersibility of carbon black is poor and the sheet surface is poor, probably because the excess silica acts as an adhesive between the carbon black particles. Further, in Comparative Example 3, since no surfactant is attached to the carbon black, the dispersion of the carbon black is poor and the electric resistance varies widely.

On the other hand, in Examples 1 to 5, since the dispersibility of carbon black was good, the surface properties were excellent, the variation in the electric resistance was small, and the resistance stability was excellent. Even in the high electric resistivity region (sheet having a small amount of carbon black blended), the electric resistance variation is small.

Examples 6 to 9 and Comparative Examples 4 to 6: Application to Resin Composition LDPE (low density polyethylene) was kneaded with 23% by weight of the carbon black of Table 3 to prepare a resin composition, which was then injected. It shape | molded and created the shaping | molding board. Similarly, an injection-molded board of a resin composition containing 26% by weight of carbon black was prepared. The volume resistivity of the obtained molded plate was measured by the same method as in Example 1, and the molded plate surface (surface smoothness) was measured.
The quality was evaluated and the results are shown in Table 3.

[0049]

[Table 3]

From Table 3, the same tendency as in the rubber composition is recognized in the resin composition. According to the present invention, it is possible to obtain a resin molded product having a small variation in electric resistance and an excellent surface smoothness. I understand.

[0051]

As described above in detail, the rubber composition and the resin composition of the present invention have excellent dispersibility of carbon black, and thus are excellent in surface smoothness and resistance stability. Obtainable.

[Brief description of drawings]

FIG. 1 is a graph showing an aggregate diameter distribution curve for _obtaining an aggregate size distribution D _1/2 / D _st .

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09C 3/10 C09C 3/10 F term (reference) 4J002 AC001 DA036 DJ016 FB076 FB086 FD316 GQ00 4J037 AA02 CA24 CB07 CB10 CB16 CB17 CC01 CC25 DD05 DD12 DD24 EE02 FF01 FF11 FF15

Claims (2)

[Claims] 1. In a rubber composition containing carbon black, the carbon black has a silica loading of 0.1 to 20% by weight, and a surfactant loading of 0.1 to 10% by weight. Aggregate size distribution D _1/2 / D _st is 0.65
1. A rubber composition characterized in that the surface-treated silica-containing carbon black is 1.1. 2. A resin composition containing carbon black, wherein the carbon black has a silica loading of 0.1 to 20% by weight, and a surfactant loading of 0.1 to 10% by weight. Aggregate size distribution D _1/2 / D _st is 0.65
1. A resin composition characterized in that the surface-active silica surface-treated carbon black is 1.1.