JPS6256118A - Manufacture of ultra-high-molecular-weight polyethylene lining roll - Google Patents

Abstract

PURPOSE:To manufacture a roll lined with ultra-high-molecular-weight polyethylene having an outer surface, prominent in shock resistance, abrasion resistance, chemical resistance as well as durability and necessitating no work for increasing the smoothness or the dimensional accuracy of the outer surface of the base body of the roll, by a method wherein the tubular body of ultra-high-molecular-weight polyethylene is heated to a temperature higher than the crystallizing temperature thereof to expand it sufficiently and is fitted to the base body of the roll, thereafter, is cooled. CONSTITUTION:In case an ultra-high-molecular-weight polyethylene tubular body, having the viscometric average molecular weight of one million or more and the average molecular weight of three million or more in light scattering method, is fitted to the cylindrical or bar-type base body of a roll, the ultra-high-molecular-weight polyethylene tubular body, having an inner diameter smaller than the outer diameter of the base body, is heated until more than 10% of the volume thereof is heated to a temperature higher than the crystallizing temperature (135-138 deg.C) thereof to expand it thermally, then, a core member is fitted thereinto under a condition that the inner diameter of the tubular body has become larger than the outer diameter of the core member, thereafter, the tubular body is cooled to shrink it. The ultra-high-molecular-weight polyethylene has a large molecular weight, therefore, it does not flow substantially when it is heated to a temperature higher than the crystallizing temperature or 135-138 deg.C normally and lower than 200 deg.C and it shows rubber-like elasticity.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for manufacturing ultra-high molecular weight polyethylene lining rolls used for various rolls, such as compression rolls, transfer rolls, table rolls, carrier rolls, etc. In detail, for rolls whose outside or outer surface is made of resin for purposes such as noise control, corrosion prevention, or preventing damage to processed products, ultra-high molecular weight polyethylene is applied as the resin on the outer surface to improve resistance. Abrasion resistance, ff resistance
This invention relates to a method for manufacturing a roll that has excellent impact resistance and chemical resistance, and does not damage processed products.

(Prior art) A roll whose outside is lined with resin is made by attaching flanges at both ends of a strong metal rod or fully bent cylinder.
A resin cylindrical body is press-fitted into the metal roll base provided with the shaft, or the resin cylindrical body is fitted and fixed by a method such as shrink fitting,
It was manufactured by grinding the outer periphery.

However, according to the above-mentioned conventional technology, since each resin has its own unique elasticity and coefficient of thermal expansion, it is necessary to improve the surface smoothness and dimensional accuracy of the metal that serves as the roll base. In order to improve the finishing accuracy of the inner surface of the cylindrical body, it is time-consuming to process it, and during shrink fitting and press fitting, the relationship between the roll diameter of the metal base and the thickness of the resin outer cylinder is taken into consideration. If the shrink-fitting and press-fitting allowances for the body are not made accurate, there is a drawback that it may become impossible to fit during shrink-fitting or press-fitting, or the resin may crack or break after fitting.

A method has also been proposed in which a heated resin cylinder is placed on the outside of the metal base roll, and a liquid resin such as urethane is injected between the metal base and the resin cylinder, and then hardened and fixed. The disadvantage is that it takes time to manufacture.

Furthermore, so-called general-purpose resins such as polyacetal, polycarbonate, and nylon used for the cylindrical body have drawbacks in either impact resistance, abrasion resistance, or chemical resistance.

(Problems to be Solved by the Invention) The present invention aims to improve these points (C1), does not require processing to improve the flatness of the outer surface of the roll base or the finished dimensional accuracy, and has impact resistance. tffi describes a method for manufacturing rolls lined with ultra-high molecular weight polyethylene that has an outer surface that is abrasion-resistant, vulgar-resistant, and durable.
This is what we provide.

(Means for Solving the Problems) That is, the present invention has a viscosity method of 1,000,000 or more, and a light scattering method of 3,000,000
When fitting an ultra-high molecular weight polyethylene cylindrical body having an average molecular weight of 1,000,000 or more into a cylindrical or rod-shaped roll base, the ultra-high molecular weight polyethylene cylindrical body having an inner diameter smaller than the outer diameter of the base is % or more, preferably 30% or more, is thermally expanded by heating until it reaches the crystallization temperature (135 to 138°C) or higher, and the core material is inserted in a state where the inner diameter is larger than the outer diameter of the core material, and then cooled. This is a method for producing an ultra-high molecular weight polyethylene lining roll, which is characterized by fixing an ultra-high molecular weight polyethylene cylindrical body to the outside of a metal base by shrinking it.

Ultra-high molecular weight polyethylene here refers to the molecular weight of general-purpose polyethylene, which has a molecular weight of about 60,000 to 300,000 when measured by a light scattering method and a viscosity of about 20,000 to 100,000, but a molecular weight of about 3,000,000 or more by a light scattering method and 1,000,000 or more by a viscosity method. It shows an extremely large value of impact resistance, compared to general-purpose polyethylene and other plastics.
This resin has excellent wear resistance and crack resistance, making it suitable for use on the outer surface of rolls.

Furthermore, due to its extremely large molecular weight, when the ultra-high molecular weight polyethylene is heated above the crystallization temperature (crystallization melting temperature), which is usually 135 to 138°C, but below 200°C, it resembles the properties of crosslinked resin and almost Does not flow and exhibits rubber-like elasticity.

Furthermore, it is opaque white at room temperature, but becomes transparent when heated above the crystallization temperature, so when heated,
You can visually determine whether the temperature is above the crystallization temperature. Moreover, the cylindrical body used in the present invention is usually formed by heating and pressurizing a powder raw material, and has the property of thermally expanding by 3 to 6% when heated from room temperature to the crystallization temperature or higher.

Therefore, even if the finished dimensional accuracy of the outer surface of the roll base is not sufficiently improved, the ultra-high molecular polyethylene cylindrical body can be easily fitted into the roll base because it thermally expands sufficiently when heated above the crystallization temperature. becomes.

Moreover, the ultra-high molecular weight polyethylene cylindrical body has a property of shrinking when cooled, and as a result, it is strongly fixed to the roll base.

Since the outer periphery of the formed roll lacks precision or smoothness, the outer periphery may be cut again.

Note that among ultra-high molecular weight polyethylene resins, those that have been heated and cooled under stretching force cannot be used because they have the property of shrinking when reheated.

Therefore, in the present invention, it is preferable to use a material that is cool-molded without applying such external force such as stretching, for example, obtained by ram extrusion molding, scrie extrusion molding, or the like.

Further, the ultra-high molecular weight polyethylene cylindrical body referred to herein may be made of ultra-high molecular weight polyethylene that has been modified by cross-filing with an organic peroxide or the like or by adding a filler or the like.

Furthermore, the core material referred to here is a rod-shaped or cylindrical body, and due to strength, rigidity, or cost considerations, it is made of metal that is formed by attaching flanges to both ends of a strong metal cylindrical body and attaching a shaft to this. This is a roll.

Hereinafter, the present invention will be explained in detail with reference to examples, but it goes without saying that the present invention is not limited to these examples.

(Example) Powder of ultra-high molecular weight polyethylene [manufactured by Hoechst I (os
The inner diameter is φ159±1m and the wall thickness is 23.5m.
When a cylindrical body with a length of 1.100U+ is heated for 30 minutes in a hot air circulation electric oven set at 150℃, it becomes a state where it can be judged that about 70% of the volume is above the crystallization temperature, and the inner diameter is It had expanded to φ165~φ167u.

An iron roll base material having a length of 1,000 mm and an outer diameter of φ164 tm was fitted into the heat-expanded ultra-high molecular weight polyethylene cylindrical body, which had flanges at both ends and a shaft attached thereto. Because ultra-high molecular weight polyethylene has rubber-like elasticity, it could be easily fitted. After cooling the ultra-high molecular weight polyethylene cylindrical body fitted with this iron roll base material in a room for 24 hours, the outer resin part was finished by cutting the outer resin part to an outer diameter of φ 200 mm and cutting both ends to the cylindrical part of the core material. did.

When this roll was used as a table roller for transporting thin iron plates, it had a durable life that was approximately twice as long as a urethane lining roll manufactured to the same dimensions.

(Example ■) Add 100 parts by weight of the above ultra-high molecular weight polyethylene powder to carbon blank (Denka Black, Denki Kagaku Co., Ltd.) 5.0 parts by weight.
Parts by weight, 0.05 parts by weight of an organic peroxide (Bahexa 25-4, manufactured by NOF ■) and 3.0 parts by weight of zinc stearate were mixed in a Henschel mixer at 80OR, P.

Mixed at the gate for 15 minutes. Next, using a ram extrusion molding machine, the outer diameter φ46, the inner diameter φ29.5±0.2, and then 310
An ultra-high molecular weight polyethylene cylindrical body having a surface resistance value of 10 3 to 10 4 Ω and antistatic performance was molded.

This cylindrical body was heated and expanded under the same conditions as in Example ① to a diameter of φ30.
Finishing was performed by cutting to X3201. When this roll was used as a paper feed roll, it was possible to obtain a roll that had antistatic properties, had excellent abrasion resistance, and was durable without paper wrapping.

Comparative Example Ultra-high molecular weight polyethylene powder (11os manufactured by Hoechst)
talen OUR #415) by a ram extruder with an outer diameter of φ 203 mm, an inner diameter of φ 165 mm, and a length of 1050 mm.
A cylindrical body of ultra-high molecular weight polyethylene of m was molded. Next, this cylindrical body was cut to have an inner diameter of 172±0.2 mm, and then left in boiling water at about 100°C for about 1 hour for heat treatment to reduce the inner diameter to φ173.0 to 175 mm. Inflated to .5 cranes.

However, although an iron roll base with an outer diameter of φ174±0.1 mm was prepared in advance, it was not possible to fit the roll base into the ultra-high molecular weight polyethylene cylindrical body. Therefore, after re-cutting the roll base so that the outer diameter was around φ 173±0.1, it was fitted into the ultra-high molecular weight polyethylene cylindrical body, and the outer peripheral surface and both ends of the completed roll were finished. processed. Thus, ultra-high molecular weight polyethylene has a crystallization temperature of 135-13
It does not expand significantly unless it is heated to a temperature of 8° C. or higher, so it can be said that heat treatment at a temperature higher than the crystallization temperature is an important requirement.

(Effects of the Invention) As described above, in the roll manufacturing method of the present invention, a cylindrical body of ultra-high molecular weight polyethylene is heated to a temperature higher than the crystallization temperature to sufficiently expand the body, and after this state is maintained and the body is fitted into the roll base. ,
By cooling, the ultra-high molecular weight polyethylene cylindrical body can be contracted and firmly fixed to the outside of the metal roll base, and the finished dimensions, precision, and smoothness of the outer surface of the roll base can be improved. This is an extremely rational method, since it is possible to insert the sufficiently expanded knot-shaped body even without it, and the dimensions and smoothness of the outer surface of the roll can be maintained by post-processing after molding.

Furthermore, since the outer peripheral surface of the roll is lined with ultra-high molecular weight polyethylene, it exhibits properties such as durability, impact resistance, and abrasion resistance, and can be used for various rolls.

Claims (1)

[Claims] 1. Ultrahigh molecular weight polyethylene having a structure in which a cylindrical body of ultra-high molecular weight polyethylene having an average molecular weight of 1 million or more as determined by the viscosity method and 3 million or more as determined by the light scattering method is fitted into a cylindrical or rod-shaped roll base. In manufacturing a high molecular weight polyethylene lining roll, an ultra high molecular weight polyethylene cylindrical body having an inner diameter smaller than the outer diameter of the roll base is heated to a temperature higher than the crystallization temperature to cause thermal expansion, so that the inner diameter becomes larger than the outer diameter of the base. A method for producing an ultra-high molecular weight polyethylene lining roll, which comprises inserting the rolled roll into the roll base body, and then cooling and shrinking the rolled roll. 2. The method for producing an ultra-high molecular weight polyethylene lining roll according to claim 1, which comprises thermally expanding the ultra-high molecular weight polyethylene cylindrical body by 3 to 6%.