JPS5980451A - Oil-containing polyethylene resin composition - Google Patents

Abstract

PURPOSE:An oil-containing resin composition, containing calcium carbonate as an inorganic filler and a polyol fatty acid ester as a lubricating oil in specific proportions in polyethylene resin, and having improved abrasion resistance, sliding characteristics and dimensional stability. CONSTITUTION:A polyethylene resin composition, containing (A) a polyethylene resin, preferably high-density polyethylene, (B) 10-20vol% calcium carbonate, preferably having <=40mu particle diameter, as an inorganic filler and (C) 3- 10vol% polyol fatty acid ester, e.g. a synthetic ester of pentaerythritol with a fatty acid, as a lubricating oil. 5-10vol% calcium carbonate and 5-10vol% acetylene black may be used as the inorganic filler of the component (B). USE:Sliding parts, slipping films, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oil-impregnated polyethylene resin composition that has good abrasion resistance and excellent sliding properties, as well as improved dimensional stability.
It relates to sliding properties, dimensional stability, and compositions.

Conventionally, adding inorganic fillers to polyethylene resins has been widely used to improve dimensional stability, as well as rigidity and heat resistance. In addition, a large number of products have been developed due to the cost reduction effect due to the effect of increasing the amount of inexpensive inorganic fillers.

Furthermore, in order to compensate for the decrease in fluidity during molding due to the addition of inorganic fillers, lubricants such as fatty acids, metal soaps, and higher alcohols are added.

However, if an inorganic filler is simply added or a lubricant is added, the wear resistance of the molded product will be extremely poor, and the cam,
At present, a polyethylene resin composition that can be used practically for sliding parts such as gears and bearings or for sliding films has not yet been obtained.

The present inventors have focused on the low coefficient of friction and low cost of polyethylene resin, and have conducted various studies to develop a polyethylene resin composition that can be practically used as sliding parts or sliding films, and as a result they have arrived at the present invention. This is what I did.

In other words, by selecting calcium carbonate from among various inorganic fillers and adding the combination of calcium carbonate and polyol-type fatty acid ester to polyethylene resin, wear resistance is significantly improved and the coefficient of friction is reduced. This is what I discovered.

The calcium carbonate used in the present invention includes heavy calcium carbonate obtained by physically crushing natural calcium carbonate minerals;
Alternatively, any precipitated calcium carbonate synthesized by chemical reaction may be used. The particle size range may be 40 microns or less, similar to those for ordinary resin filling, and commercially available products can be used as they are. It is also possible to surface-treat existing coupling agents in order to increase their affinity with polyethylene resin and improve their dispersibility.

The amount of calcium carbonate added needs to be 10 to 20% by volume relative to the composition. If the amount of calcium carbonate added is too small, the filling effect will be poor and the molded product will lack dimensional stability. If the amount is more than 20% by volume, the strength of the molded product will be greatly reduced, making it unpractical as a sliding component.

The polyol-type fatty acid ester used in the present invention is a synthetic ester of a polyol such as pentaerythritol, trimethylolpropane, neopentyl glycol, etc. and a fatty acid. The effect of improving wear resistance was discovered. The amount added needs to be 3 to IO% by volume relative to the composition. That is, if the amount added is less than 3% by volume,
If the lubricating effect is not sufficient and the amount exceeds 10% by volume, oil separation occurs during molding, which not only reduces processability but also significantly reduces the strength of the molded product.

The polyethylene resin used in the present invention may be either low-density polyethylene or high-density polyethylene, but preferably high-density polyethylene has excellent mechanical strength.

The composition described in claim 1 has excellent dimensional stability and sliding properties, and is electrically insulating like polyethylene resin. For this reason, static electricity may cause problems in processing and actual use, especially for applications such as films.

Therefore, the present inventors proposed the second patent as a device that has antistatic properties without impairing dimensional stability and sliding characteristics.
The composition described in 1.

That is, calcium carbonate and acetylene black are used simultaneously as inorganic fillers, and the total amount of the inorganic fillers is 10 to 20% by volume relative to the composition, and the volume ratio of acetylene black to the composition is is 5~
] Add so that the amount is 0% by volume.

The reason why the total amount of inorganic fillers added is defined as 10 to 20% by volume is the same as in the case of the composition according to claim 1.
If it is less than 10% by volume, the dimensional stabilization effect of the molded product will be poor, and if it is more than 20% by volume, the strength of the molded product will be greatly reduced. The reason why the amount of acetylene black added is specified as 5 to 10% by volume is that if it is less than 5% by volume, the electrical resistance will be high and no antistatic effect will be obtained, whereas if it is more than 10% by volume, the anti-wear effect will be poor. This is because the sex is significantly impaired.

The products of the present invention can be processed by conventional extrusion molding or injection molding, and examples of applications include injection molded parts such as gears, cams, and rollers, and extrusion molded tubes, sheets, films, and pipes.

Furthermore, it is easily possible to add existing flame retardants, ultraviolet absorbers, fiber reinforcing materials, lubricants, etc. to the composition of the present invention.

Examples are given below to show examples of their effects, but the present invention is not limited to the following examples unless the gist thereof is exceeded.

(Example 1) Showa Yuka @) Showa Rex (trade name) was used as polyethylene resin, and Bihoku Funka Kogyo @) was used as calcium carbonate.
After adding and mixing 15% by volume of Softon 2200 (trade name) manufactured by Nippon Oil & Gas Co., Ltd. and 5% by volume of Unistar H (trade name) manufactured by NOF@) as a polyol-type fatty acid ester, this was extruded using a screw extruder and pelletized. , injection molded into a predetermined shape.

(Example 2) In Example 1), 6% by volume of calcium carbonate was used as an inorganic filler, and acetylene black (manufactured by Denki Kagaku Kogyo@))
was set at 9% by volume.

(Example 8) In Example 2), the composition was extruded using a screw set extruder and made into pellets, and then a T-die extruder was used to make a film with a thickness of 0.
．． A 11 nWL film was extruded.

(Comparative Example 1) Talc was used instead of calcium carbonate in Example 1).

(Comparative Example 2) Barium sulfate was used instead of calcium carbonate in Example 1).

(Comparative Example 3) Acetylene black was used instead of calcium carbonate in Example 1).

(Comparative Example 4) Nioctyl ester (manufactured by Toei Chemical @) was used instead of the polyol-type fatty acid ester in Example 1).

The physical properties of these materials are shown in Table 1.

Table 1 (Note) Friction property test conditions Compatible material 1s450 cylinder (9.6m 11.6dah MM
) Surface ÷600 Emery polishing load i15 (45 Kyytmt) Peripheral speed i1 B, 2 m/min Sliding time: 10 min Lubrication; Dry -9--417

Claims (2)

[Claims] (1) An oil-impregnated polyethylene resin composition characterized in that a polyethylene resin contains 10 to 20% by volume of calcium carbonate as an inorganic filler and 3 to 20% by volume of a polyol-type fatty acid ester as a lubricating oil. (2) Acetylene black is used at the same time as calcium carbonate as an inorganic filler, and 5 to 10 volume % of calcium carbonate and 5 to 10 volume % of acetylene black are added to the total volume. The oil-impregnated polyethylene resin composition according to item 1.