JPS59126446A - Ultra-high-molecular-weight polyethylene resin composition - Google Patents

Abstract

PURPOSE:The titled composition having improved flow properties during melting without damaging high impact resistance and wear resistance of ultra-high- molecular-weight polyethylene, obtained by blending an ultra-high-molecular- weight polyethylene resin with a widely used polyolefin resin in a specific ratio. CONSTITUTION:95-50pts.wt. (preferably 90-85pts.wt.) ultra-high-molecular- weight polyolefin resin(having >=1,000,000mol.wt., <=0.01 melt index at 20kg load) is blended with 5-50pts.wt. (preferably 10-25pts.wt.) widely used polyolefin resin(polyolefin resin modified with silane having preferably <=150,000mol.wt.), to give the desired composition. EFFECT:Capable of providing a molded article having improved mechanical properties in high productivity by using a widely used extrusion or injection molding machine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultra-high molecular weight polyethylene composition that has improved flowability during melting without impairing the various properties of the ultra-high molecular weight polyethylene resin.

So-called super-learning molecular weight polyethylene resins with a viscosity average molecular weight of 1 million or more have excellent impact resistance, abrasion resistance, chemical resistance, etc., and their use as engineering plus materials is expanding.

However, although it has these characteristics, compared to general-purpose resins, it has a high viscosity when melted and poor fluidity, so it is very difficult to mold by normal extrusion molding or injection molding, and a special mechanism is required for molding. There was a drawback that there was no reasonable alternative molding method other than using an extrusion molding machine or the like having the same equipment, and the productivity was poor.

In addition, ultra-high molecular weight polyethylene has a melting point (approximately 136'C
) When exposed for a certain period of time, thermal decomposition occurs and the molecular weight decreases to 100,000 or less, which has the disadvantage that the various properties of ultra-high molecular weight polyethylene described above are impaired.

In view of the above-mentioned drawbacks, the present invention improves fluidity during melting, does not cause a decrease in molecular weight, and uses a molding machine commonly used for extrusion or injection molding of general-purpose resins. This was done with the aim of providing a resin composition that can be extremely efficiently molded into products with high productivity and excellent performance, and its gist is that 95 to 50 parts by weight of an ultra-high molecular weight polyethylene resin, It consists in an ultra-high-volume polyethylene resin composition formed by mixing 5 to 50 parts by weight of a general-purpose polyolefin resin.

Generally speaking, the ultra-high molecular weight polyethylene resin used in the present invention includes those having an average molecular weight determined by a viscosity method of y1 million or more and a melt index at a load of 20 mm or less of αo1 or less. As the ultra-high molecular weight polyethylene resin, a commercially available product can be used as it is, and in this case, it is preferable to use a powdered one.

General-purpose polyolefin resins used in the present invention include, for example, polyethylene, polypropylene, polybutene, ethylene e-propylene copolymer, ethylene/vinyl acetate copolymer, chlorinated polyethylene, ethylene/vinyl chloride copolymer, ethylene/acrylic Examples include resins such as acid ester copolymers, among which polyolefin resins in which crosslinking agents such as organic peroxides are added to these resins, vinyltriethoxysilane, vinyltritoxysilane, vinylmethyldimethoxysilane, etc. A silane-modified polyolefin resin modified with a silane compound and added with a silanol bonding catalyst such as diptyltin silacrate or dioctyltin silacrate is preferably used.

In this case, crosslinking occurs by performing post-treatments such as heat treatment and hot water treatment, thereby further improving the mechanical properties of the molded article.

Further, in the present invention, when comparing the molecular weight of the general-purpose olefin resin to the molecular weight of the ultra-high molecular weight polyethylene resin, it is preferable that the viscosity average molecular weight is 150,000 or less. The reason for this is that when the viscosity average molecular weight exceeds 150,000, it is not possible to improve the fluidity of the ultra-high molecular weight polyethylene resin when melting, which has difficult fluidity, and the moldability of the composition is poor, resulting in a general-purpose molding machine. This is because it cannot be molded with high productivity and efficiency using extrusion or injection.

In the present invention, ultra-high molecular weight polyethylene resin 9.5~
50 parts by weight of the above-mentioned ultra-high molecular weight polyethylene resin and 5-50 parts by weight of a general-purpose polyolefin resin, preferably 90-75 parts by weight of the above-mentioned ultra-high molecular weight polyethylene resin and 10-25 parts by weight of the above-mentioned general-purpose polyolefin resin. It is better to mix the parts.

Thus, in the present invention, the reason why 5 to 50 parts by weight of a general-purpose polyolefin resin is mixed with 95 to 50 parts by weight of an ultra-high molecular weight polyethylene resin is that the amount of polyolefin resin blended is 5 parts by weight. If the amount is less than 50 parts by weight, the moldability of the composition will be poor and productivity and efficient molding will not be possible, and if it exceeds 50 parts by weight, the moldability of the composition will be improved, but on the contrary, the This is because excellent properties such as impact resistance, abrasion resistance, and chemical resistance are impaired, and the mechanical properties of the molded article are deteriorated.

The composition of the present invention can be obtained by a simple operation of uniformly stirring and mixing a predetermined amount of polyolefin resin with an ultra-high molecular weight polyethylene resin (preferably in powder form) using, for example, a Henschel mixer. It will be done.

In addition, in the composition of the present invention, commonly used additives such as antioxidants, stabilizers, pigments, and lubricants may be added as appropriate and necessary.

The composition of the present invention can be molded into various profiles such as tubular, plate, and sheet shapes by molding means such as extrusion or injection, and the molded products are suitable for applications in fields where wear resistance, chemical resistance, etc. are required. .

The present invention will be explained below with reference to Examples.

Examples 1-10. Comparative Examples 1 to 4 Ultra-high molecular weight polyethylene resins with molecular weights of 2 million (trade name Hi-zex Million 240M, manufactured by Mitsui Petrochemicals) and 3 million (trade name Hi-zex Million 340) were used.
M, manufactured by Mitsui Petrochemical Co., Ltd.), and polyolefin resin with a density of 0.950 and melt-in 7'' NOX Z
50, and water-crosslinkable silane-modified acute polyethylene obtained by graft-modifying medium-density polyethylene with a density of 0.935 and melt index of 5.0 with vinyltritoxysilane, and mixed the two in various ratios. A composition having the blending ratio shown in was prepared.

Each composition was evaluated for fluidity, moldability, and mechanical properties. Fluidity evaluation is based on ASTM standard (D-1
238) and the melt index was measured.

Evaluation of formability was performed using a 65φ single extrusion root at an extrusion temperature of 2.
It was molded into a flat plate at 00°C.

After crosslinking the molded product by immersing it in a hot water bath at 80°C for 12 hours, the molded product has a tensile strength of D-6 according to the same standard.
38), impact strength (according to the same standard D-256) and abrasion degree (according to the same standard D-1175) were measured. The amount of wear is 2000
Represents the amount of decrease due to wear. These measurement results are also listed in Table 1.

As a comparative example, the same evaluations as in the examples were conducted on the single systems shown in Table 1. Of these, for Comparative Example 1.3, the above-mentioned molded article for mechanical property evaluation was formed by press molding, and the same measurements were conducted.

The measurement results are also listed in Table 1.

In the formability in the table above, the mark X indicates that it cannot be extruded.
The mark Δ indicates that the extrusion speed is slow but extrusion is possible, ○ indicates that extrusion is good, and ■ indicates that extrusion is extremely good.

As is clear from Table 1, according to the composition of the present invention, ultra-high molecular weight polyethylene resin having difficult flow properties can be obtained without reducing mechanical properties such as impact resistance and abrasion resistance of ultra-high molecular weight polyethylene resin. The fluidity of the resin is improved, the moldability is excellent, and a molded article with excellent mechanical properties can be obtained, and its practical value is extremely large.

patent applicant Sekisui Chemical Co., Ltd. Representative: Mototoshi Fujinuma 3

Claims (1)

[Claims] L: 95 to 50 parts by weight of ultra-high molecular weight polyethylene resin;
An ultra-high molecular weight polyethylene resin composition prepared by mixing 5 to 50 parts by weight of a general-purpose polyolefin resin. 2. The ultra-high molecular weight polyethylene resin composition according to claim 1, wherein the general-purpose polyolefin resin is a silane-edible polyolefin resin.