JPS601245A - Ultra-high-molecular-weight polyethylene composition - Google Patents

Abstract

PURPOSE:To enable thin materials and special shapes to be easily molded by improving moldability, by blending an arom. ring compd. (derivative) and a 12- 32C aliph. carboxylate salt with ultra-high-molecular-weight polyethylene. CONSTITUTION:5-70pts.wt. at least one member (A) selected from an arom. ring compd. (e.g. ethylbenzene), an arom ring compd. derivative (e.g. naphthalene) and halogenated compd. thereof (e.g. chlorotoluene) and 0.1-20pts.wt. C12-C32 aliph. carboxylate salt (B) (e.g. calcium stearate or calcium montanate) are blended with 100pts.wt. ultra-high-molecular-weight polyethylene having an MW of 1,000,000 or above to obtain the desired ultra-high-molecular-weight polyethylene compsn. This compsn. exhibits excellent extrusion stability by the viscosity lowering action of component A and the lubricity adjusting action of component B.

Description

[Detailed description of the invention] The present invention relates to ultra-high molecular weight polyethylene compositions.

Ultra-high molecular weight polyethylene with a molecular weight of 1,000,000 or more has superior properties in many respects, such as wear resistance and impact resistance, as compared to polyethylene of 90% polyethylene. However, ultra-high molecular weight polyethylene has a drawback of extremely poor moldability due to its high melt viscosity.

There is a problem in that it can only be molded by compression molding, which has low productivity. Therefore, molding of thin objects such as sheets or irregular shapes cannot be achieved by one-step molding, and currently, thin objects are obtained by slicing thick objects, and irregularly shaped objects are obtained by cutting.

In order to eliminate the above-mentioned drawbacks of ultra-high molecular weight polyethylene, it is necessary to provide one flowability after the two-particle coalescence to lower the viscosity during molding.

Attempts have been made to improve moldability by adding additives to ultra-high molecular weight polyethylene.

For example, Japanese Patent Application Publication No. 1983. JP-A-139442 discloses an ultra-high molecular weight polyethylene composition containing a specific amount of thermosetting polyimide resin, and JP-A-57-1') 331 discloses a group of aliphatic compounds and alicyclic compounds. Ultra-high molecular weight polyethylene compositions have been proposed in which one or a mixture of two or more selected flow improvers that are solid at room temperature are blended. but.

None of the compositions has been able to achieve a satisfactory viscosity reduction, and therefore efficient extrusion cannot be expected.

An object of the present invention is to provide an ultra-high molecular weight polyethylene composition that can be easily molded into thin or irregularly shaped objects without impairing their physical properties.

The gist of the present invention is to combine ultra-high molecular weight polyethylene with a molecular weight of 1 million or more, at least one compound selected from the group consisting of aromatic ring compounds, aromatic ring compound derivatives, and their halogen compounds, and an aliphatic C,1-C32 carbon. It is arranged with an acid salt. [11 High molecular weight polyethylene compositions]

Examples of aromatic ring compounds used in the present invention include ethylbenzene, n-hexylbenzene, cyclohexylbenzene, n-butylhenzene, C3,5-triethylbenzene, mesitylene (C(+13 (CI+, )3), isodurene (Ct112 (CH2)) +) (more than liquid).

, durene (C4H3(CH3)+), pentamethylbenzene, hexamethylbenzene, hexamethylbenzene (all solids), and the like.

Examples of aromatic ring compound derivatives include 9.

Examples include naphthalene and indene.

The halogen compounds for each of the above compounds include 1, for example, chlorotoluene, 2 to chloroparaxylene (liquid), parasitic ruhenzene, dichloronaphthalene (solid)
etc.

At least one compound from each group of the above-mentioned compounds is added to the ultra-high molecular weight polyethylene in a ratio of 2 to 5, for example, to 100 parts by weight of ultra-high molecular weight polyethylene. 70 car p part is preferred. Each of these compounds plays a role as a viscosity reducing agent.

In addition, two aliphatic carboxylic acid salts used in the present invention include:
Preferably, those having C+z to Cn have good sustainability of activity against heat history. Examples thereof include calcium stearate and calcium monocinate. The blending ratio is 9, for example, 0 to 100 parts by weight of ultra-high molecular weight polyethylene.
．． 1 to 20 parts by weight is preferred. This salt acts as a slipperiness regulator.

It is desirable that the above-mentioned additives be blended by heating and impregnating the ultra-high molecular weight polycarbonate at a temperature close to the crystal melting point of tyrene (approximately 140° C.). This is because the gaps between the crystals of ultra-high molecular weight polyethylene are greatest near the crystal melting point, and it is in this state that the additive most often enters the ultra-high molecular weight polyethylene.

The ultra-high molecular weight polyethylene composition of the present invention uses at least one compound selected from the group consisting of aromatic ring compounds, aromatic ring compound derivatives, and their halogen compounds as a viscosity reducing agent.

The melt viscosity is significantly lower than that of conventional compositions. Therefore, since the particle cohesiveness of ultra-high molecular weight polyethylene is significantly improved and its flowability is good, extrusion molding becomes possible and production speed can be improved. In addition, an aliphatic C12-C3λ carboxylic acid salt is used as a lubricity modifier together with the viscosity reducing agent.

The critical shear rate is greatly improved, the extrusion molding stability is excellent, and molded products of various shapes, whether thin or irregularly shaped, can be extruded without impairing the original physical properties of the molded product.

Next, examples of the present invention will be shown.

[Example 1] Ultra-high molecular weight polyethylene 100i with a molecular weight of 2 million or more
(I part, 20 parts by weight of cyclohexyl hensef, and 2 parts by weight of calcium moncitate were mixed in a Henschel mixer for 14 hours.
A sheet was extruded using a composition stirred and compounded at 0°C.

The extruder is 9011! Using an I-axis extruder, the die has a width of 1
A sheet die having a diameter of 000 mm and a thickness of 2111+ was used.

The molding conditions and results are shown in Table 1. The comparative example is ultra-high molecular weight polyethylene containing no additives.

Table 1 [Example 2] Compositions having the blending ratios shown in Table 2 were extruded under the same conditions as in [Example 1].

Table 2 Molding conditions and results are shown in Table 3. The comparative example is ultra-high molecular weight polyethylene containing no additives.

Table 3* shows the results using molded products in the current compression molding process.

As is clear from Table 1, there is no significant difference in physical properties between the extrusion molded products of the two compositions of the present invention and the conventional compression molded products. That is, the composition of the present invention does not impair the essential physical properties of ultra-high molecular weight polyethylene, such as excellent wear resistance. Furthermore, as can be seen from Table 2, the compositions of the present invention are also excellent in impact resistance.

Applicant: Sekisui Chemical Co., Ltd. Representative: Mototoshi Ugenuma

Claims (1)

[Claims] 1) At least one compound selected from the group consisting of aromatic ring compounds, aromatic ring compound derivatives, and their halogen compounds and an aliphatic C+l-C32 carboxylate are arranged on ultra-high molecular weight polyethylene having a molecular weight of 1 million or more. Ultra-high molecular weight polyethylene composition.