JP2593678B2 - Ultra high molecular weight polyethylene composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ultra-high molecular weight polyethylene resin having an antistatic function. More specifically, the present invention relates to an ultra-high molecular weight polyethylene resin, which is less susceptible to electrification due to friction and the like, is less susceptible to the influence of the environment on electric characteristics, and is more favorable. Has the appearance,
The present invention relates to an ultrahigh molecular weight polyethylene-based composition having an antistatic function suitable mainly for use in sliding parts that dislike static electricity.

(Prior art) Ultra-high molecular weight polyethylene has excellent properties such as excellent wear resistance and impact resistance and low coefficient of friction. It is used as a lining material for hoppers and chutes, as well as bearings, rollers and guide rails. However, since the electric resistance is large and easily charged, dust and the like are caused to adhere.

Therefore, ultra-high molecular weight polyethylene filled with carbon black, metal powder, etc. for the purpose of antistatic,
A method using a conventional kneading type or surface coating type antistatic agent has been proposed.

Furthermore, Japanese Patent Publication No. 60-238365 discloses that a specific amount of a specific particulate silicic acid or silicate, a glycerin and an organic electrolyte having a salt structure are blended in a synthetic resin in a specific amount, and has volume conductivity. Moreover, a colorable conductive resin composition has been proposed.

(Problems to be Solved by the Invention) However, those filled with carbon black, metal powder, etc. for antistatic purposes have a problem that the appearance is unsightly and the friction partner material is damaged. Was limited. In addition, an antistatic agent kneaded or coated on the surface has problems such as a loss of effect due to friction of the resin surface and washing with water, and a large fluctuation in the effect due to the influence of use temperature and humidity. Was.

In addition, the conductive resin composition has a problem in that the constituent silica is extremely fine particles, and if the silicate contains water, the mechanical strength of the resin itself is impaired due to the water of crystallization. Was.

The present invention is intended to solve such problems, and has a small charge due to friction and the like, and its electrical characteristics are hardly affected by the environment such as abrasion and washing, the appearance is beautiful, and the ultra-high molecular weight excellent in mechanical strength is also excellent. An object is to provide a polyethylene-based resin composition.

(Means for Solving the Problems) Therefore, in order to solve the above problems, the present invention provides:
Ultra high molecular weight polyethylene powder 100 parts by weight, particle size 0.5 to
It is characterized in that 4 to 30 parts by weight of at least one inorganic filler selected from 10.0 μm calcium carbonate or barium sulfate, 1.0 to 5.0 parts by weight of an antistatic agent and 0.1 to 2.0 parts by weight of glycerin.

The ultrahigh molecular weight polyethylene referred to in the present invention is a generic name of commercially available powdered ultrahigh molecular weight polyethylene having an average molecular weight of 1,000,000 or more by a viscosity method and 3,000,000 or more by a light scattering method. For example, Hostalen GUR of Hoechst, and Hi-zex Mil of Mitsui Petrochemical Industries, Ltd.
lion).

The inorganic filler used in the present invention is calcium carbonate and barium sulfate, the average particle size is 0.5 ~ 10.0μm
The mixing amount is preferably in the range of 4 to 30 parts by weight. Average particle size is 0.
If it is less than 5 μm or if the amount exceeds 30 parts by weight, mechanical properties such as impact strength are reduced, and the average particle size is 10.0 μm.
If the amount is more than 4 parts by weight or less than 4 parts by weight, the intended antistatic function cannot be sufficiently obtained, especially under low humidity and after washing with friction.

In addition, calcium carbonate referred here has an average particle diameter of 0.5
It is precipitated calcium carbonate or heavy calcium carbonate having a thickness of about 10.0 μm. In the case of calcium carbonate, the amount is preferably 4 to 20 parts by weight, more preferably 5 to 20 parts by weight.
10 parts by weight.

The barium sulfate referred to here has an average particle size of 0.6 to 1
Barium sulfate or eluent barium sulfate having a particle diameter of 0.0 μm. In the case of barium sulfate, the compounding amount is suitably 6 to 30 parts by weight, more preferably 9 to 20 parts by weight.

When the above-described calcium carbonate and barium sulfate are mixed, the compounding ratio does not adversely affect the antistatic function and the like, but the compounding amount is ultra-high molecular weight polyethylene powder 10
The amount is 5 to 25 parts by weight with respect to 0 parts by weight, and if the amount is out of the range, the same problems as described above occur.

In addition, the antistatic agent referred to here is a liquid or powdery surfactant which is generally kneaded into a polyolefin resin and is used as a nonionic type such as an alkyl ether of polyoxyethylene, an alkylamino ether, or an anionic type. For example, alkali salts (soap) of higher fatty acids, quaternary ammonium salts as cations, and amino acids as zwitterionics are used in amounts of 1.0-5.
0 parts by weight, preferably 1.5 to 3.0 parts by weight. The amount
If the amount exceeds 5.0 parts by weight, the antistatic agent migrates to the resin surface, causing a bleed phenomenon, which is likely to cause stickiness,
The improvement in electrical properties is also reduced. On the other hand, when the amount is less than 1.0 part by weight, the electric characteristics are not sufficiently improved.

The glycerin referred to here is generally commercially available purified glycerin, and its blending amount is 0.1 to 2.0 parts by weight, preferably 0.2 to 1.0 part by weight, based on 100 parts by weight of the ultrahigh molecular weight polyethylene powder. If the compounding amount exceeds 2.0 parts by weight, a block is formed at the time of kneading, and the diffusion is inhibited.In addition, glycerin migrates to the resin surface to cause a bleeding phenomenon as described above, which is likely to cause stickiness, and the improvement in electric characteristics is small. Become. On the other hand, if it is less than 0.1 part by weight, the intended antistatic function cannot be sufficiently obtained.

The present invention provides an ultrahigh molecular weight polyethylene resin-based composition with an antistatic function by combining at least one inorganic filler selected from calcium carbonate or barium sulfate with an antistatic agent and glycerin as described above. To impart higher mechanical strength, but to improve the appearance by further adding a pigment or the like to the composition, to improve abrasion resistance by crosslinking with an organic peroxide, and the like. It is also possible to impart various properties by adding a filler.

Furthermore, the ultra-high molecular weight polyethylene resin composition of the present invention is similar to the usual molding method of ultra-high molecular weight polyethylene powder,
By compression molding, ram extrusion molding, injection molding, etc., plates, rods,
Manufactured into pipes, odd-shaped products, etc.

Hereinafter, the present invention will be described in detail with reference to Examples, but it goes without saying that the present invention is not limited thereto.

(Examples and Comparative Examples) Powder of ultra-high molecular weight polyethylene (Hostal manufactured by Hoechst)
en GUR 412) and powdered calcium carbonate with different average particle diameters (Shiraishi Kogyo Co., Ltd. Shirayuka CC, Takehara Chemical Co., Ltd.)
Sunlight # 1000, etc.) or powdered barium sulfate (special product, manufactured by Sakai Chemical Co., Ltd.), liquid antistatic agent (Matsumoto Yushi Seiyaku Co., Ltd. TB-128) as an antistatic agent, glycerin (Kao Corporation) (Purified glycerin) were added at the mixing ratios shown in Table 1 and mixed at 800 rpm for 15 minutes in a Henschel mixer. Next, 80 g of the mixed powder was weighed, filled into a plate making mold (inner surface 125 mm × 210 mm), and pressed by a press.
0kgf / cm ² × 5 min after precompression, set the press heating platen to 230 ° C., then heated for 45 minutes at a surface pressure of 40 kgf / cm ^2, further 100 kgf / cm ²
A plate having a thickness of 3 mm was formed by cooling at a surface pressure of 30 mm for 30 minutes, and a test piece for measuring electrical characteristics of 120 mm wide × 100 mm long was prepared from this. In addition, 350 g of the above compounded powder was weighed, and a 13 mm thick plate was formed in the same manner as the 3 mm plate (however, the heating time was 80 minutes).
From this, Izod impact test pieces were prepared.

As electrical characteristics, surface resistance was measured. The surface resistance was measured using the above test piece at 20 ° C and 65% humidity in an atmosphere of 4329A HIGH RESISTA manufactured by Yokogawa Hewlett-Packard Co., Ltd.
Measured using NCE METER and 16008A RESIS-TIVITY CELL. Izod impact strength is 1 width from the 13mm thick plate
A test piece with a size of 2.7 mm x thickness 12.7 mm x length 63.5 mm, notch depth 2.54 mm is cut out and JIS using a 92.0 kgfcm hammer.
It was measured according to K7110.

 Table 2 shows the results.

As can be seen from Tables 1 and 2, at least one inorganic filler selected from calcium carbonate and barium sulfate is added to the composition in which only an antistatic agent and glycerin are added to ultra high molecular weight polyethylene (Comparative Example 6). The resulting compositions (Examples 1 to 5 and Comparative Examples 1 to 5) have low electric resistance values on the surface, and exhibit an effect of preventing static charge. However, a composition in which the average particle size of calcium carbonate is less than 0.5 μm or the amount exceeds 20 parts by weight (Comparative Example 1.2) is not sufficient in impact resistance, and a composition in which the average particle size exceeds 10.0 μm. (Comparative Example 3) has a relatively high electric resistance value. That is, the validity of the regulation range of the average particle diameter and the amount of the calcium carbonate (average particle diameter 0.5 to 10.0 μm, the amount of the compound 5 to 20 parts by weight) is shown. In addition, the composition containing only one of the antistatic agent and glycerin (Comparative Example 4.5) has the same other conditions as compared with the composition containing both the antistatic agent and glycerin (Example 1). Obviously, the electric resistance value is high, and it can be seen that both the antistatic agent and glycerin independently provide an antistatic effect.

(Effects) As described above, the ultrahigh molecular weight polyethylene composition of the present invention uses ultrahigh molecular weight polyethylene in combination with at least one inorganic filler selected from calcium carbonate and barium sulfate, an antistatic agent, and glycerin within the above-mentioned regulatory range. By blending, it has a low surface resistance and has an antistatic function, so it does not contaminate or damage the mating material when used as a sliding member, and it also has antistatic due to friction, washing, etc. Sliding parts that do not lose function, are not affected by operating temperature and humidity, have high mechanical strength such as impact strength, and are white in appearance and easy to be colored. This has the effect that a good composition can be obtained for use.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location C08K 3:26 3:30 5:00 5: 053)

Claims (1)

(57) [Claims] (1) at least one inorganic filler selected from calcium carbonate or barium sulfate having a particle size of 0.5 to 10.0 μm per 100 parts by weight of ultrahigh molecular weight polyethylene powder;
~ 30 parts by weight, antistatic agent 1.0 ~ 5.0 parts by weight and glycerin
An ultra-high-molecular-weight polyethylene composition, wherein 0.1 to 2.0 parts by weight is blended.