JP2000356216A - Plastic roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a long plastic roller by forming a coating layer by directly compression-molding polyethylene powder of ultrahigh molecular weight on an outer peripheral surface of a core body. SOLUTION: A plastic roller has a coating layer 2 formed by compression- molding polyethylene of ultrahigh molecular weight onto an outer peripheral surface of a core body 1. As the core body 1, a bar or a tube made of metal such as carbon steel, stainless steel and the like can be preferably used because of their durability to high temperature and high pressure in compression molding. As polyethylene of ultrahigh molecular weight, that having a viscosity average molecular weight of 500,000-8,000,000, preferably 1,000,000-6,000,000 can be used. As polyethylene of ultrahigh molecular weight suitable for the compression molding, the powdered polyethylene having a particle size of 10-2,000 μm, a limiting viscosity of 5-50 dl/g in decalin at 135 deg.C, a condentration of powder of 0.920-0.970, and a bulk density of 0.35-0.55 can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roller made of a thermoplastic material.

2. Description of the Related Art Conventionally, as a roller made of a thermoplastic material, for example, a core made of metal or the like is pressed into a pipe obtained by a method of mechanically grinding a round bar of ultra-high molecular weight polyethylene, or the like. Alternatively, a material obtained by shrink-coating an ultra-high molecular weight polyethylene shrink pipe on the outside of a core material has been used.

Among the above-mentioned conventional plastic rollers, the one in which the core is pressed into the former pipe is difficult to obtain a long roller due to the press-in resistance. There is a problem that it is not compatible with transfer rollers for objects to be transferred, such as semiconductor wafers, which are becoming too large. The process of once expanding the diameter of a polyethylene pipe is complicated, and there is a dislike that a special expanding device is required also in terms of equipment. Therefore, an object of the present invention is to obtain a long plastic roller having a coating layer of ultrahigh molecular weight polyethylene.

SUMMARY OF THE INVENTION The present invention relates to a plastic roller having a coating layer formed by compression molding ultra-high molecular weight polyethylene powder directly on the outer peripheral surface of a core. By forming the coating layer of ultrahigh molecular weight polyethylene by compression molding, a long plastic roller can be obtained without the problem of press-in resistance.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of the plastic roller of the present invention, FIG. 2 is a schematic cross-sectional view showing an example of an apparatus for manufacturing the plastic roller of FIG. 1, and FIG. It is a schematic sectional drawing which shows the other example of the apparatus of FIG. The present invention relates to a plastic roller having a coating layer 2 formed on the outer peripheral surface of a core 1 by compression molding of ultrahigh molecular weight polyethylene as shown in FIG. In the present invention, the core 1
A rod-like or tubular one made of a metal such as carbon steel or stainless steel is preferable because it can withstand high temperatures and high pressures during compression molding. In the present invention, the ultrahigh molecular weight polyethylene forming the coating layer 2 has a viscosity average molecular weight of 5
Those of about 100,000 to 8,000,000, preferably about 1,000,000 to 6,000,000 can be used. The ultrahigh molecular weight polyethylene suitable for compression molding is a powder having a particle size of 10 μm to 2000 μm, an intrinsic viscosity in decalin of 5 to 50 dl / g at 135 ° C., and a powder density of 0.920 to
0.970 and a bulk density of 0.35 to 0.55 can be used. In order to manufacture the plastic roller of the present invention, it is necessary to form the coating layer 2 by directly compression molding ultra-high molecular weight polyethylene powder on the outer peripheral surface of the core 1. As a specific means for forming the coating layer 2 by compression molding, for example, as shown in FIG. 2, the core 1 is set between a box-shaped heating pedestal 30 and a heating and pressing plate 31, Further, filling with ultra high molecular weight polyethylene powder 20,
There is a method of heating and pressurizing. On the inner surfaces of the heating cradle 30 and the heating and pressing plate 31, a semi-cylindrical mold surface 32 having a shape substantially corresponding to the outer diameter of the target plastic roller is formed. At the end, a core receiving groove 33 for supporting the core 1 at a position substantially at the center of the plastic roller is formed. In addition, an electric heater 34 for heating and a water cooling pipe 35 for cooling can be installed on the heating cradle 30 and the heating and pressing plate 31. In order to form the coating layer 2, first, the mold surface 32 of the heating cradle 30 is filled with approximately half the ultra-high molecular weight polyethylene powder 20, and the core 1 is set so as to fit into the core receiving groove 33. The ultra high molecular weight polyethylene powder 20 is filled. Next, the heating / pressing plate 31 is pressurized from above by a pressing device (not shown) toward the heating cradle 30 for a predetermined time, and then water-cooled, the heating / pressing plate 31 is removed, and the plastic roller may be taken out. Further, as another means, as shown in FIG.
2 is inserted, and the core 1 is set substantially at the center of the inside of the cylindrical outer mold 40. Next, the space between the core 1 and the inner surface of the outer mold 40 is filled with ultrahigh molecular weight polyethylene powder 20. Further, the ultra-high molecular weight polyethylene powder 20 is pressed from the opening of the outer mold 40 in the axial direction by a cylindrical pressing die 41 which matches the space between the core 1 and the inner surface of the outer mold 40, and It is only necessary to heat the mold 40 from the outside for a predetermined time and then cool it, then pull out the pressing mold 41 and take out the plastic roller. As conditions for the compression molding, the temperature of the inner surface of the mold is 150 ° C. to 250 ° C. as the heating temperature, and 10 to 50 K as the compression pressure.
g / cm2, and the heating time is preferably 1 minute to 30 minutes. The plastic roller obtained by such a method may be subjected to cutting or the like in a separate step for the purpose of improving the accuracy of the outer diameter, centering or surface finishing.

The present invention is a plastic roller in which a coating layer is formed by compression molding ultra-high molecular weight polyethylene powder directly on the outer peripheral surface of a core body. By forming the coating layer of ultrahigh molecular weight polyethylene, a long plastic roller can be obtained without the problem of press-in resistance.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a plastic roller of the present invention.

FIG. 2 is a schematic sectional view showing an example of an apparatus for producing the plastic roller of FIG.

FIG. 3 is a schematic sectional view showing another example of an apparatus for producing the plastic roller of FIG.

[Explanation of symbols]

 1 core body 2 coating layer

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[Procedure amendment]

[Submission date] June 15, 1999 (1999.6.1
5)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction contents]

[Document Name] Statement

[Title of the Invention] Plastic roller

[Claims]

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roller made of a thermoplastic material.

[0002]

2. Description of the Related Art Conventionally, as a roller made of a thermoplastic material, for example, a core made of metal or the like is pressed into a pipe obtained by a method of mechanically grinding a round bar of ultra-high molecular weight polyethylene, or the like. Alternatively, a material obtained by shrink-coating an ultra-high molecular weight polyethylene shrink pipe on the outside of a core material has been used.

[0003]

Among the above-mentioned conventional plastic rollers, the one in which the core is pressed into the former pipe is difficult to obtain a long roller due to the press-in resistance. There is a problem that it is not compatible with transfer rollers for objects to be transferred, such as semiconductor wafers, which are becoming too large. The process of once expanding the diameter of a polyethylene pipe is complicated, and there is a dislike that a special expanding device is required also in terms of equipment.

Therefore, an object of the present invention is to obtain a long plastic roller having a coating layer of ultrahigh molecular weight polyethylene.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a plastic roller having a coating layer formed by compression molding ultra-high molecular weight polyethylene powder directly on the outer peripheral surface of a core. By forming the coating layer of ultrahigh molecular weight polyethylene by compression molding, a long plastic roller can be obtained without the problem of press-in resistance.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing an example of the plastic roller of the present invention, FIG. 2 is a schematic sectional view showing an example of an apparatus for manufacturing the plastic roller of FIG. 1, and FIG. It is an outline sectional view showing other examples of a device for manufacture.

The present invention relates to a plastic roller having a coating layer 2 formed on the outer peripheral surface of a core body 1 by compression molding of ultra-high molecular weight polyethylene as shown in FIG.

In the present invention, the core 1 is made of carbon steel,
Rods and tubes made of metal such as stainless steel
It is preferable because it can withstand high temperature and high pressure during compression molding.

In the present invention, as the ultrahigh molecular weight polyethylene forming the coating layer 2, those having a viscosity average molecular weight of 500,000 to 8,000,000, preferably about 1,000,000 to 6,000,000 can be used.

Ultrahigh molecular weight polyethylene suitable for compression molding is a powder having a particle size of 10 μm to 2000 μm, and has an intrinsic viscosity of 5 to 5 at 135 ° C. in decalin.
0 dl / g and the powder density is 0.920 to 0.97
0 and a bulk density of 0.35 to 0.55 can be used.

In order to manufacture the plastic roller of the present invention, it is necessary to form the coating layer 2 by compression molding ultra-high molecular weight polyethylene powder directly on the outer peripheral surface of the core 1.

As a specific means for forming the coating layer 2 by compression molding, as shown in FIG. 2, for example, the core 1 is set between a box-shaped heating pedestal 30 and a heating and pressing plate 31. In addition, there is a method of further filling the ultrahigh molecular weight polyethylene powder 20, heating and pressurizing.

A semi-cylindrical mold surface 32 having a shape substantially corresponding to the outer diameter of the target plastic roller is formed on the inner surfaces of the heating cradle 30 and the heating and pressing plate 31. At both end portions of the core 31, core receiving grooves 33 for supporting the core 1 at a position substantially at the center of the plastic roller are formed.

The heating cradle 30 and the heating and pressing plate 31
Can be provided with an electric heater 34 for heating and a water cooling pipe 35 for cooling.

In order to form the coating layer 2, the mold surface 32 of the heating cradle 30 is first filled with approximately half of the ultrahigh molecular weight polyethylene powder 20, and the core 1 is set so as to fit into the core receiving groove 33. , The remaining ultra high molecular weight polyethylene powder 20
Fill.

Next, the heating / pressing plate 31 is pressurized from above by a pressing device (not shown) toward the heating cradle 30 for a predetermined time, then cooled with water, and the heating / pressing plate 31 is removed to remove the plastic roller.

As another means, as shown in FIG.
The core 1 is set at approximately the center inside the cylindrical outer mold 40 so that the core supports 42 are inserted into both ends of the core 1.

Next, the space between the core 1 and the inner surface of the outer mold 40 is filled with ultrahigh molecular weight polyethylene powder 20.

Further, the ultra-high molecular weight polyethylene powder 20 is pressed in the axial direction from the opening of the outer die 40 by a cylindrical pressing die 41 corresponding to the space between the core 1 and the inner surface of the outer die 40. While heating from the outside of the outer mold 40 for a predetermined time and then cooling, the pressing mold 41 is extracted, and the plastic roller may be extracted.

The conditions for the compression molding are as follows: the heating temperature is 150 ° C. to 250 ° C., the compression pressure is 10 to 50 Kg / cm ² , and the heating time is 1 hour.
Minutes to 30 minutes is preferred.

The plastic roller obtained by such a method may be subjected to cutting or the like in a separate step for the purpose of improving the accuracy of the outer diameter, centering or surface finishing.

[0023]

The present invention is a plastic roller in which a coating layer is formed by compression molding ultra-high molecular weight polyethylene powder directly on the outer peripheral surface of a core body. By forming the coating layer of ultrahigh molecular weight polyethylene, a long plastic roller can be obtained without the problem of press-in resistance.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a plastic roller of the present invention.

FIG. 2 is a schematic sectional view showing an example of an apparatus for producing the plastic roller of FIG.

FIG. 3 is a schematic sectional view showing another example of an apparatus for producing the plastic roller of FIG.

[Explanation of symbols] 1 core body 2 coating layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29L 31:32 F term (Reference) 3J103 AA02 AA13 AA24 AA51 EA02 EA03 EA11 EA12 EA20 FA15 FA18 FA30 GA02 HA03 HA05 HA41 HA42 4F100 AB03 AB04 AK04B AT00A BA02 DA16 DD31 DE01B EJ20B GB51 GB90 JA07B 4F204 AA06 AC01 AD03 AD12 AD15 AD18 AG03 AG08 AG14 AH04 FA01 FB01 FB12 FE06 FF01 FF05 FF50 FN11 FQ01 FQ15 FW24

Claims (1)

[Claims] 1. A plastic roller having a coating layer formed by compression molding ultra-high molecular weight polyethylene powder directly on the outer peripheral surface of a core.