JPH06340799A - Electrically conductive resin composition - Google Patents

Abstract

PURPOSE:To provide a resin composition highly excellent in electrical conductivity while retaining excellent characteristics inherent in the polyester resin. CONSTITUTION:The resin composition highly excellent in electrical conductivity can be obtained, without impairing excellent characteristics inherent in the polyester resin, by incorporating (A) an aromatic thermoplastic polyester resin with (B) a small amount of specific electrically conductive carbon black(CB). Among others, CB >=350ml/100g in dibutyl phthalate oil absorption heightens the electrical conductivity of the composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molding material used for a photosensitive drum of a copying machine and gears attached to the photosensitive drum, and more particularly to a polyester resin composition having relatively high conductivity.

[0002]

2. Description of the Related Art A photosensitive drum of a copying machine or the like needs to be charged in order to transfer toner, and a metal such as aluminum which is a conductor is generally used. However, from the viewpoints of workability, mass productivity, and lightness, substitution of a resin having conductive properties is under consideration. It is said that the electrical conductivity required for these uses is that the volume resistivity is about 10 ³ Ω · cm or less, and it is not necessarily a so-called good conductor. Conventionally, resin has been made conductive by using conductive powder such as metal powder, carbon powder, metal fiber such as aluminum, stainless steel, brass, metal coated glass fiber, conductive fiber such as carbon fiber, aluminum flakes, carbon flakes. It is achieved by blending a conductive filler such as Of these conductive fillers, carbon black is the most common, and among them, Ketjen black is known to give a high degree of conductivity with a small amount. However, when a large amount of carbon black or the like is added to the resin, there arises a drawback that mechanical strength and other excellent properties of the original base resin are impaired. From this point of view, the present inventors have diligently studied to obtain a high conductivity effect by blending a relatively small amount of conductive carbon black into the thermoplastic resin, and as a result, the aromatic thermoplastic polyester resin has a DBP oil absorption of 350 ml. The inventors have found that it is possible to obtain a predetermined level of conductive resin by using a conductive carbon black having a weight ratio of / 100 g or more, and have reached the present invention.

[0003]

OBJECTS OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to achieve excellent conductivity without deteriorating the excellent characteristics of the aromatic thermoplastic polyester resin as a base. It is to provide a resin composition.

[0004]

DETAILED DESCRIPTION OF THE INVENTION The conductive resin composition of the present invention comprises (A) an aromatic thermoplastic polyester resin and (B) a conductive carbon black having a DBP oil absorption of 350 ml / 100 g or more (2 to 20% by weight (vs. The entire composition) and a conductive resin composition.

The present invention is described in detail below.

The aromatic saturated polyester resin (A) used in the present invention uses terephthalic acid or 2,6-naphthalenedicarboxylic acid or an ester-forming derivative thereof as a main acid component, and has 2 carbon atoms as a main glycol component. Targeting linear saturated polyesters obtained by using glycols of 10 to 10 or ester-forming derivatives thereof, for example, polyethylene terephthalate (PET),
Examples thereof include polypropylene terephthalate, polybutylene terephthalate (PBT), polyhexamethylene terephthalate, polycyclohexane 1,4-dimethylene terephthalate, polybutylene 2,6-naphthalate (PBN) and the like. Among these, especially PET, PBT, PB
N is preferred.

The term "mainly" as used herein means 80 mol% or more, preferably 90 mol% or more, based on all acid components or all glycol components. Further, a part of the acid component or glycol component may be replaced with another copolymerization component. Such copolymerizable acid components include aromatic dicarboxylic acids other than terephthalic acid and 2,6-naphthalenedicarboxylic acid, such as isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenylketone. Examples thereof include dicarboxylic acids, diphenylsulfonedicarboxylic acids and the like, aliphatic dicarboxylic acids such as succinic acid, adipic acid and sebacic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, tetralindicarboxylic acid and decalindicarboxylic acid. 2 to 2 carbon atoms
Examples of the copolymerizable glycol component other than the glycol of 10 are tricyclodecane dimethylol, bisphenol A, bisphenol B, bishydroxyethoxy bisphenol A and the like. In addition, a polyfunctional compound such as glycerin, trimethylolpropane, pentaerythritol, trimellitic acid, and pyromellitic acid may be copolymerized as long as the polyester resin does not substantially lose the molding performance. These aromatic saturated polyester resins may be used alone or as a mixture of two or more kinds.

The conductive carbon black which is the component (B) of the present invention has a DBP oil absorption of 350 ml / 100 g or more. It has been found that when a conductive carbon black having this DBP oil absorption is blended, a high amount of conductive performance is exhibited even when added in a small amount. The amount of the conductive filler added is 2 to 20% by weight based on the total amount of the resin composition. When the amount added is less than 2% by weight, good conductivity, which is the effect of the present invention, cannot be obtained. On the other hand, when the amount added is 20% by weight or more, the resin composition obtained has poor moldability and poor mechanical strength. Not suitable as a molding material.

The conductive resin composition according to the present invention may contain other additives, if desired, within a range that does not significantly impair the properties thereof.
For example, stabilizer, colorant, ultraviolet absorber, release agent, antistatic agent, crystallization accelerator, crystal nucleating agent, filler, impact modifier,
Flame retardants and the like can be added.

Any compounding method can be used to obtain the resin composition of the present invention. Usually, it is preferable to disperse these compounding components more uniformly, and a method of mixing all or part of them simultaneously or separately, for example, with a mixer such as a blender, a kneader, a Banbury mixer, a roll or an extruder to homogenize them. Alternatively, a method in which a part of the mixed portion is mixed simultaneously or separately with, for example, a blender, a kneader, a mixer, a roll, an extruder, etc., and the remaining components are mixed with these mixers or an extruder to homogenize You can Further, a method of melt-kneading a previously dry-blended composition with a heated extruder to homogenize it, extruding it into a wire shape, and then cutting it into a desired length and granulating it can be exemplified.

The resin composition obtained by the present invention can be molded extremely easily by a usual method using a general thermoplastic resin molding machine.

[0012]

EXAMPLES The present invention will be supplemented by the following examples. In addition,
Various properties in the examples were measured by the following methods. (1) Tensile strength: ・ Measuring machine ... Shimazu Seisakusho Autograph AG-50
00A ・ Test conditions… Compliant with ASTM D638 (2) Volume resistivity: ・ Measurement machine… Made by Mitsubishi Yuka Co., Ltd. Loresta AP MCP
-T400-Test conditions-Pin spacing 1.5 mm-Test piece used-disk (50 mmφ x 3 mmt) (3) Flammability-Compliant with UL-94 test method (test piece thickness;
Displayed at equivalent level by 1/8 inch) (4) DBP oil absorption ... A sample dried at 125 ° C. for 1 hour was used as an obsodometer (Cabot type B manufactured by Brabender) using dibutyl phthalate (DBP). Measured

[0013]

Examples 1 to 12 and Comparative Examples 1 to 3 The various raw materials shown in Table 1 were uniformly mixed in a tumbler in a predetermined amount ratio, and then vacuumed by using a vented twin-screw extruder having a screw diameter of 44 mm. Cylinder temperature 240-280 while pulling
Melt-kneading was carried out at a temperature of 40 ° C. and a discharge rate of 40 kg / h, and the threads discharged from the die were cooled and cut to obtain molding pellets.

The pellets were then used in an injection molding machine having an injection capacity of 5 ounces to measure strength and volume resistivity under the conditions of an injection pressure of 800 kg / cm ² , a cooling time of 15 seconds, and a total molding cycle of 40 seconds. A test piece was molded and used for measurement.

The results of these tests are shown in Table 1. In addition,
The following raw materials were used as various raw materials shown in Table 1. PET: Teijin Ltd. PET resin TR8550 PBT ... Teijin Ltd. PBT resin TRB-J PBN ... Teijin Ltd. PBN resin C8000 GF ... Nitto Boseki glass fiber (3PE47)
4) Flame retardant: Teijin Kasei's brominated flame retardant (FG7
100) Flame-retardant aid ... Antimony trioxide (AT) manufactured by Nippon Seiko Co., Ltd.
OX-S) Conductive carbon black CBA ... Ketjen black CBB ... Ketjen black CBC ... Graphite CBD ... acetylene black

[0016]

[Table 1]

As is clear from the results shown in Table 1, when the amount of conductive carbon black added is large, the volume resistivity is low, and the conductivity is good, but the tensile strength tends to be low.
However, when the conductive carbon black exhibiting a specific oil absorption amount according to the present invention is used, the volume resistivity becomes small and the conductivity becomes good without the tensile strength being significantly lowered.

Claims (2)

[Claims] 1. A thermoplastic aromatic polyester resin,
Dibutyl phthalate (DBP) oil absorption is 350ml / 1
2 to 20 wt% of conductive carbon black of 00 g or more
(Vs total composition). 2. The conductive resin composition according to claim 1, wherein the polyester resin is at least one resin selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate and polybutylene naphthalene dicarboxylate.