JP2003165902A - Rubber composition, vulcanized rubber composition and vulcanized material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a vulcanized material that has a consistent specific volume resistance against temperature and humidity fluctuations, and that shows no bleeding and no blooming. <P>SOLUTION: A vulcanizing agent is blended with a rubber composition comprising 100 pts.wt. of an epichlorohydrin rubber and 0.1-15 pts.wt. of a quaternary ammonium salt represented by the formula 1: (N<SP>+</SP>R<SP>1</SP>R<SP>2</SP>R<SP>3</SP>R<SP>4</SP>)X<SP>-</SP>(wherein R<SP>1</SP>, R<SP>2</SP>, R<SP>3</SP>and R<SP>4</SP>are each an allyl group, or a substituted or unsubstituted alkyl group where at least one of the groups is an allyl group or a substituted alkyl group with an allyl group; and X<SP>-</SP>is an anion). The mixture is then subjected to vulcanization. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a rubber composition, a vulcanizable rubber composition and a vulcanized product of the vulcanizable rubber composition which are useful as a material for a conductive roll.

[0002]

2. Description of the Related Art For rubber materials such as charging rolls used in electrophotographic copying machines, 10 ^{4 to} 1.5 × 10 ⁷ Ω · c
It is often required to have a volume resistivity value of about m. The conductive rubber material is generally formed of a composition in which conductive powder such as carbon black or metal powder, or a conductivity-imparting material such as conductive carbon fiber is mixed in synthetic rubber. However, in such a conductive rubber material, the conductivity is expressed by the contact between the conductivity-imparting materials mixed in the synthetic rubber, but the conductivity-imparting materials do not uniformly contact each other, and the volume resistivity It is difficult for the values to be uniform. This tendency is remarkable especially in the range of the volume resistivity of steam.

In order to solve such a problem, it has been proposed to use a rubber material containing an epichlorohydrin-ethylene oxide copolymer having a small volume specific resistance value (JP-A-1-142569). Although the volume resistivity of this copolymer is uniform, it is not possible to maintain a constant volume resistivity due to fluctuations in the external temperature during polymerization, and a volume resistivity larger than the above range is used. May have. Furthermore, the charging roll using this copolymer may have a problem that the volume resistivity value increases when a DC voltage is continuously applied for a long time.

In order to solve this problem, at least one rubber selected from the group consisting of acrylonitrile-butadiene rubber, epichlorohydrin rubber and acrylic rubber, a composition comprising an epichlorohydrin-ethylene oxide copolymer and a quaternary ammonium salt. It has been proposed to use a vulcanized product (Japanese Patent Laid-Open No. 6-264919).
Issue). In this method, the increase in the volume specific resistance value due to the application of the DC voltage is small, and the volume specific resistance value can be adjusted by the amount of the quaternary ammonium salt. However, the vulcanized product of this composition has a new problem that the quaternary ammonium salt causes bleeding or blooming.

On the other hand, as a semiconductive rubber material whose volume resistivity is stable against changes in ambient temperature and humidity, a halogen-containing polyether polymer, --CH ₂ CH _{2, is used.}
A composition containing a quaternary ammonium salt having a ₂ O-structure has been proposed (JP 2001-19843A). However, the vulcanized product of this composition also has the drawback that the quaternary ammonium salt causes bleeding or blooming under high temperature and high humidity conditions.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a vulcanizate which is stable against temperature and humidity fluctuations and has no bleeding or blooming.

[0007]

As a result of intensive studies, the present inventors have found that the above problem can be solved by using a quaternary ammonium salt having an allyl group, and based on this finding, As a result, the present invention has been completed.

Thus, according to the present invention, a rubber composition containing a polymer containing an epihalohydrin rubber and a quaternary ammonium salt represented by the following general formula 1, and a vulcanizing agent in the rubber composition. A vulcanizable rubber composition prepared by blending and a vulcanized product obtained by vulcanizing the vulcanizable rubber composition are provided. Formula ^{1: (N + R 1 R} 2 R 3 R 4) X - ( ^{wherein, R 1, R 2, R} 3 and ^{R 4,} carbon atoms of 30 or less carbon atoms - a group having a carbon double bond, Other than that, it represents a substituted alkyl group or an unsubstituted alkyl group, at least one is a group having a carbon-carbon double bond having 30 or less carbon atoms, and X ⁻ represents an anion.)

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The epihalohydrin rubber used in the present invention is a rubber containing an epihalohydrin monomer. Those having an epihalohydrin unit content of 10 to 100 mol%, an alkylene oxide unit of 0 to 90 mol% and an unsaturated epoxide unit of 0 to 15 mol% are preferable, and an epihalohydrin unit of 20 to 98 mol% and an alkylene oxide unit of 10 to 80 mol% are preferable. More preferably those containing 1 to 12 mol% of unsaturated epoxide units, 35 to 97 mol% of epihalohydrin units, 20 to 70 mol% of alkylene oxide units, and 2 to 10 mol% of unsaturated epoxide units. Is particularly preferable.
If the number of epihalohydrin units is too small, the rubber composition of the present invention tends to retain water, has high tackiness, and has poor processability. If the alkylene oxide units are too small, the conductivity of the vulcanizate may be poor, and if it is too large, the hygroscopicity of the vulcanizate may be high, and the fluctuation of the conductivity due to the environment may be large. If the unsaturated epoxide units are too small, the vulcanized product may have a low vulcanization density and the compression set may be inferior, whereas if it is too large, the vulcanized product may be brittle due to heat-curable deterioration. is there.

Examples of epihalohydrin include epichlorohydrin, epibromohydrin, epiiodohydrin and the like, with epichlorohydrin being preferred.

The alkylene oxide preferably has 10 or less carbon atoms, more preferably 5 or less carbon atoms, and 3
The following are particularly preferred. Specifically, ethylene oxide, propylene oxide, etc. are illustrated, and ethylene oxide is preferable.

The unsaturated epoxide has an epoxy group,
It is a compound having a carbon-carbon unsaturated bond in the molecule.
It preferably has 10 or less carbon atoms, more preferably 8 or less carbon atoms, and particularly preferably 6 or less carbon atoms. Specific examples include allyl glycidyl ether, glycidyl methacrylate, glycidyl acrylate, and butadiene monooxide, with allyl glycidyl ether being preferred.

The Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the epihalohydrin type rubber is not particularly limited, but is 20
To 200 is preferable, 25 to 120 is more preferable, and 30 to 100 is particularly preferable. If the Mooney viscosity is too low, the tensile strength may be low, and the processability of the rubber composition may be poor. If the Mooney viscosity is too high, the vulcanizate may have high hardness.

The method for producing the epihalohydrin rubber is not particularly limited, and it may be produced by a known method.

In the present invention, a polymer other than epihalohydrin rubber may be blended. The amount thereof is preferably 20 per 100 parts by weight of epihalohydrin rubber.
It is 0 part by weight or less, more preferably 150 parts by weight or less, particularly preferably 100 parts by weight or less. The polymer other than the epihalohydrin-based rubber to be blended is not particularly limited, but a polymer having a polar group is preferable.

In the present invention, the polar group means an atomic group containing atoms other than carbon atoms and hydrogen atoms. The polymer having a polar group is a polymer obtained by polymerizing using a monomer having a polar group or a polymer having a polar group introduced into the polymer by modification, and is other than epihalohydrin rubber. Examples of the polymer polymerized using a monomer having a polar group include chloroprene rubber, polymers of halogen-containing monomers such as fluororubber, acrylonitrile-butadiene copolymer rubber, and methacrylonitrile-butadiene copolymer rubber. Polymers of α, β-ethylenically unsaturated nitrile monomers or hydrogenated products thereof, (meth) acrylic acid polymers such as acrylic rubber and ethylene-acrylic copolymer rubber, and urea compounds such as urethane rubber. Copolymers, polymers of silicon oxides such as silicone rubber, ethylene oxide-propylene oxide copolymers, polyether-based polymers obtained by ring-opening polymerization of oxides such as ethylene oxide-propylene oxide-allyl glycidyl ether copolymer, etc. Is mentioned. Examples of the polymer having a polar group introduced into the polymer by modification include chlorosulfonated polyethylene and maleic anhydride addition polymer.
Among these, chloroprene rubber, acrylonitrile-
Butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber hydrogenated product, acrylic rubber, ethylene-acrylic copolymer rubber, urethane rubber, ethylene oxide-
Propylene oxide copolymer, ethylene oxide-
Propylene oxide-allyl glycidyl ether copolymer, chlorosulfonated polyethylene rubber are preferred,
Acrylonitrile-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber hydrogenated product, acrylic rubber, ethylene oxide-propylene oxide copolymer, ethylene oxide-propylene oxide-allyl glycidyl ether copolymer, chlorosulfonated polyethylene rubber are more preferable. .

The quaternary ammonium salt used in the present invention is
It is represented by the general formula 1. Formula ^{1: (N + R 1 R} 2 R 3 R 4) X - ( ^{wherein, R 1, R 2, R} 3 and ^{R 4,} carbon atoms of 30 or less carbon atoms - a group having a carbon double bond, Other than that, it represents a substituted alkyl group or an unsubstituted alkyl group, at least one of which is a group having a carbon-carbon double bond having 30 or less carbon atoms, and X ⁻ represents an anion.)

The group having a carbon-carbon double bond having 30 or less carbon atoms may contain atoms other than carbon atom and hydrogen atom, but is preferably a group composed of only carbon atom and hydrogen atom. is there. 20 or less is preferable and, as for carbon number, 10 or less is more preferable. Preferably allyl group, methallyl group,
It is a substituted alkyl group having an allyl group or a substituted alkyl group having a methallyl group, and more preferably an allyl group or a substituted alkyl group having an allyl group. Examples of the substituted alkyl group having an allyl group include a 3-butenyl group (CH ₂ CHCH ₂ CH ₂ —) and a 4-pentenyl group (C
H ₂ CHCH ₂ CH ₂ CH ₂ —), 5-hexenyl group (CH ₂ CHCH ₂ CH ₂ CH ₂ CH ₂ —), 6-heptanyl group (CH ₂ CHCH ₂ CH ₂ CH ₂ CH ₂ CH ₂
-), 1-Arirubuchiru group _{(CH 2 CH 2 CH 2 C} (C
H ₂ CHCH ₂₎ H-), and the like. Carbon number 30
When there are a plurality of groups having the following carbon-carbon double bond, they may be the same or different from each other.

The substituted alkyl group other than the group having a carbon-carbon double bond having 30 or less carbon atoms preferably has 1 carbon atom.
00 or less, more preferably 30 or less, particularly preferably 2
It is 0 or less. If the carbon number is too large, the volume resistivity value may increase. Examples of the substituted alkyl group include a 2-hydroxyethyl group and a 2-methoxyethyl group. When there are a plurality of substituted alkyl groups, they may be the same or different from each other.

The unsubstituted alkyl group preferably has 100 or less carbon atoms, more preferably 30 or less carbon atoms, and particularly preferably 20 or less carbon atoms. When there are a plurality of unsubstituted alkyl groups, they may be the same or different from each other. Preferred unsubstituted alkyl groups include a methyl group, an ethyl group, a propyl group, an isopropyl group, and an octadecyl group.

[0021] In the Formula 1, X ^- anion represented by,
Although not particularly limited, halogen ions are preferable. Examples thereof include chlorine ion, bromine ion and iodine ion, and chlorine ion is particularly preferable.

The quaternary ammonium salt used in the present invention is
Preferred are allyltrimethylammonium chloride, allyltriethylammonium chloride,
Examples thereof include diallyldimethylammonium chloride, diallylmethyldimethylammonium chloride, allyldimethyloctylammonium chloride, allyldimethyloctadecylammonium chloride, diallyldimethylammonium chloride and diallylmethyldimethylammonium chloride.

The rubber composition of the present invention comprises 100 parts by weight of an epihalohydrin type rubber and the above quaternary ammonium salt of 0.1.
1 to 15 parts by weight. The compounding amount of the quaternary ammonium salt is preferably 0.2 to 10 parts by weight, more preferably 0.3 to 7.0 parts by weight, based on 100 parts by weight of the epihalohydrin rubber. If the blending amount of the quaternary ammonium salt is too small, the conductivity is poor,
If the amount is too large, the quaternary ammonium salt tends to be deposited on the surface of the vulcanized product, and if deposited, the conductivity may be poor, or the conductivity may vary depending on the site of the vulcanized product.

The vulcanizable rubber composition of the present invention comprises the above rubber composition and a vulcanizing agent. The vulcanizing agent is not particularly limited as long as it vulcanizes the epihalohydrin rubber, and examples thereof include sulfur, organic peroxides, mercaptotriazines, and thioureas. As organic peroxides, ketone peroxides, peroxyesters,
Examples thereof include diacyl peroxides and alkyl peroxides. Examples of thioureas include thiourea, dibutylthiourea and triethylthiourea. When the polymer other than the epihalohydrin rubber is contained, a vulcanizing agent that co-vulcanizes between the epihalohydrin rubber and the other polymer is preferable. The type and blending amount of these vulcanizing agents are determined according to the amount of the polymer other than the epihalohydrin-based rubber, and the blending amount of the vulcanizing agent is preferably 0.1 to 100 parts by weight of the epihalohydrin-based rubber. 10 parts by weight, more preferably 0.15 to 7 parts by weight, particularly preferably 0.2 to 5 parts by weight.

In the present invention, if necessary, a vulcanization aid, a vulcanization accelerator, etc. can be used together with the vulcanization agent.
The vulcanization aid and the vulcanization accelerator are not particularly limited, and the type and blending amount may be determined according to the type and amount of the polymer other than the epihalohydrin rubber, the type of the vulcanizing agent, and the like.

In the rubber composition and vulcanizable rubber composition of the present invention, if necessary, an antioxidant, an antioxidant, a light stabilizer, a vulcanization retarder, a scorch inhibitor, a filler and a reinforcing agent. ,
Compounding agents such as processing aids, lubricants, pressure-sensitive adhesives, lubricants, flame retardants, mildew-proofing agents, colorants, and conductivity imparting agents can be further compounded.

The rubber composition and vulcanizable rubber composition of the present invention are roll-mixed, Banbury-mixed, screw-mixed,
It can be prepared by an appropriate mixing method such as solution mixing. The order of compounding is not particularly limited, but when melt-kneading, a filler that is difficult to decompose by heat, a compounding agent such as an antioxidant is added and sufficiently mixed to obtain a rubber composition containing no vulcanizing agent. After the preparation, it is preferable to prepare a vulcanizable rubber composition by mixing a compounding agent such as a vulcanizing agent and a vulcanization aid, which reacts with heat, at a temperature lower than the vulcanization starting temperature in a short time. When mixing at a temperature lower than the vulcanization start temperature, all compounding agents may be compounded under the same conditions.

The vulcanizable rubber composition of the present invention is vulcanized by heating. The molding method and the vulcanization method of this vulcanizable rubber composition are not particularly limited, and if necessary, such as the shape and work efficiency of the vulcanizate, molding and vulcanization are performed simultaneously, or
It may be vulcanized after molding.

When vulcanizing the vulcanizable rubber composition of the present invention, the vulcanization temperature is preferably 130 to 200 ° C., more preferably 140 to 200 ° C., and the vulcanization time is generally 1
The range is from minutes to 15 hours. Even if the surface is hardened and the shape is fixed once it has been vulcanized once, it may not be vulcanized to the inside.As secondary vulcanization, heating may be performed slowly to vulcanize to the inside. Sometimes preferred.

As a heating method, a method used for vulcanizing the polymer such as press heating, steam heating, oven heating, hot air heating, heating by infrared rays or microwave may be appropriately selected.

[0031]

The vulcanized product of the present invention is semi-conductive, stable to environmental changes, excellent in normal physical properties, and resistant to bleeding and blooming. Therefore, for example, in a wide range of fields such as electronic rolls, electricity, and construction, including rubber rolls, belts, blades and drum materials in electrophotographic devices such as printers and copiers.
It is useful as an elastic member, a covering material, a protective material, etc. that requires conductivity.

[0032]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. The parts are based on weight.

The volume resistivity value was obtained by producing a vulcanized rubber sheet test piece, sandwiching it between electrodes with a guide ring, and applying a voltage of 500 V DC at 10 ° C. and a humidity of 20% (1),
23 ° C, 50% humidity condition (2) and 35 ° C, 8 humidity
It was measured in the unit of Ω · cm measured under the condition (3) of 0%.
The fluctuation range between the conditions (1) and (2) is represented by log (L) − when the volume specific resistance values (Ω · cm unit) of the conditions (1) and (2) are represented by L and N, respectively. It is the value of log (N), and the fluctuation range between the conditions (2) and (3) is the condition (2).
And the volume resistivity (Ω · cm unit) of the condition (3) are represented by N and H, respectively, they are log (N) -log (H).

The surface state of the vulcanized product was visually observed by observing the surface of the above-mentioned test piece visually, in which no bleeding or blooming occurred, ◯, bleeding occurred in B1, and blooming occurred. It was evaluated as B2.

Example 1 Epichlorohydrin-based rubber (epichlorohydrin unit content 40 mol%, ethylene oxide unit content 56 mol%, allyl glycidyl ether unit content 4 mol%, Mooney viscosity (ML _{1 + 4} , 100 ° C.) 60) 100 Parts, calcium carbonate (filler) 30 parts, zinc white (reinforcing agent) 5
Parts, stearic acid (processing aid) 1 part, sulfur 0.3 part, tetraethyl thiuram disulfide (vulcanization accelerator) 1.2
Parts and allyl trimethyl ammonium chloride 1.
3 parts were kneaded at 50 ° C. using a roll.

1. A rubber composition having a thickness of 2.
Take it out as a sheet of 2 ± 0.1 mm, and remove it at 160 ℃ for 3
Press-crosslink for 0 minutes with a pressing pressure of 10 MPa, 150
A crosslinked rubber sheet test piece having a size of mm × 150 mm and a thickness of 2 mm was manufactured and each measurement was performed. The results are shown in Table 1.

Example 2 The same procedure as in Example 1 was carried out except that 3.5 parts of allyldimethyloctadecyl ammonium chloride was used instead of 1.3 parts of allyl trimethyl ammonium chloride. The results are shown in Table 1.

Example 3 1.5 parts of diallyldimethylammonium chloride instead of 1.3 parts of allyltrimethylammonium chloride
Processing was carried out in the same manner as in Example 1 except that parts were used. The results are shown in Table 1.

Example 4 The same procedure as in Example 1 was carried out except that 1.6 parts of allyl-2-hydroxyethyldimethylammonium chloride was used instead of 1.3 parts of allyltrimethylammonium chloride. The results are shown in Table 1.

Comparative Example 1 The same treatment as in Example 1 was carried out except that allyltrimethylammonium chloride was not added. The results are shown in Table 1.

Comparative Example 2 The same treatment as in Example 1 was carried out except that 1 part of lithium perchlorate was used instead of 1.3 parts of allyltrimethylammonium chloride. The results are shown in Table 1.

Comparative Example 3 Tetrabutylammonium perchloride 3.2 instead of 1.3 parts of allyltrimethylammonium chloride
Processing was carried out in the same manner as in Example 1 except that parts were used. The results are shown in Table 1.

Comparative Example 4 The procedure of Example 1 was repeated except that oleylbis (2-hydroxyethyl) methylammonium (1.9 parts) was used instead of allyltrimethylammonium chloride (1.3 parts). The results are shown in Table 1.

[0044]

[Table 1]

Although the vulcanizate containing no quaternary ammonium salt represented by the general formula 1 (Comparative Example 1) is not shown in this measurement result, the quality of the epichlorohydrin-based rubber is deteriorated due to temperature fluctuation during polymerization. Because of variations, the volume resistivity value fluctuates even under constant measurement conditions. The vulcanizates (Comparative Examples 2 to 4) containing a general conductivity-imparting agent without using the quaternary ammonium salt represented by the general formula 1 were subjected to constant measurement by adjusting the content of the conductivity-imparting agent. Under certain conditions, a constant volume resistivity value can be obtained. However, with this vulcanizate,
The volume resistivity fluctuated greatly with temperature and humidity, and blooming or bleeding was observed.

The vulcanizates (Examples 1 to 4) containing the epichlorohydrin-based rubber and the quaternary ammonium salt represented by the general formula 1 are the compounding amounts of the quaternary ammonium salt represented by the general formula 1. By adjusting, the constant volume resistivity value can be obtained under constant measurement conditions. Furthermore, this vulcanizate is
Fluctuations in volume resistivity due to changes in temperature and humidity are small, and blooming and bleeding are not observed.

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Claims (3)

[Claims] 1. 100 parts by weight of epihalohydrin-based rubber and 0.1 to 4 of a quaternary ammonium salt represented by the following general formula 1.
A rubber composition containing 15 parts by weight. Formula ^{1: (N + R 1 R} 2 R 3 R 4) X - ( ^{wherein, R 1, R 2, R} 3 and ^{R 4,} carbon atoms of 30 or less carbon atoms - a group having a carbon double bond, it Represents a substituted alkyl group or an unsubstituted alkyl group other than, and at least one is a group having a carbon-carbon double bond having 30 or less carbon atoms, and X ⁻ represents an anion.) 2. A vulcanizable rubber composition obtained by compounding the rubber composition according to claim 1 with a vulcanizing agent. 3. A vulcanized product obtained by vulcanizing the rubber composition according to claim 2.