JP2003003019A - Ultrahigh molecular weight polyethylene resin composition for skived film, thick-walled molded article for skived film, method of manufacturing skived film of ultrahigh molecular weight polyethylene and skived film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ultrahigh molecular weight polyethylene resin composition for a skived film capable of giving a skived film of ultrahigh molecular weight polyethylene which has an excellent abrasion resistance and uniform quality such as transparency and to provide a thick-walled molded article for a skived film and a method of manufacturing a skived film of ultrahigh molecular weight polyethylene. SOLUTION: The ultrahigh molecular weight polyethylene resin composition for a skived film contains an ultrahigh molecular weight polyethylene having an inherent viscosity [η]of 5.0-35 dl/g determined in decalin at 135 deg.C and an organic peroxide. A thick-walled molded article for a skived film obtained by press-forming the ultrahigh molecular weight polyethylene resin composition, a method of manufacturing a skived film of ultrahigh molecular weight polyethylene in which a film is manufactured by skiving a thick-walled molded article of an ultrahigh molecular weight polyethylene resin obtained by forming an ultrahigh molecular weight polyethylene resin composition containing an ultrahigh molecular weight polyethylene and an organic peroxide, and a skived film obtained by the method are also provided.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an ultra-high molecular weight polyethylene resin composition for cutting film, a thick-walled molded product for cutting film, an ultra-high molecular weight polyethylene cutting film (skive film, skive film, ultra-high molecular weight produced by cutting method). More specifically, it relates to a method for producing a polyethylene film) and a cutting film, more specifically, an ultra-high molecular weight polyethylene resin composition for cutting film, which is excellent in abrasion resistance and has a constant transparency and other quality, and a cutting film. TECHNICAL FIELD The present invention relates to a thick-walled molded product, a method for producing an ultrahigh molecular weight polyethylene cutting film, and a cutting film obtained by the method.

[0002]

TECHNICAL BACKGROUND OF THE INVENTION Ultra-high molecular weight polyethylene is extremely tougher than ordinary polyethylene, and is extremely excellent in abrasion resistance, lubricity, impact resistance at low temperatures, etc. It is used in various applications such as battery separators, chemical tanks, automobile tanks, machine parts, and food tanks. However, since ultra-high molecular weight polyethylene has a very high melt viscosity, it is significantly inferior in moldability as compared with ordinary polyethylene and the like.

Therefore, at the beginning, after the slab, sheet, rod, block and the like were formed by compression molding from ultra-high molecular weight polyethylene, the final product was obtained by machining such as cutting. After that, various molding methods were developed and materials were selected, injection molding and extrusion molding became possible, and film-like materials made of ultra-high molecular weight polyethylene were manufactured by various methods. .

Among these various types of molded products made of ultrahigh molecular weight polyethylene, examples of the method for producing an ultrahigh molecular weight polyethylene film include (a): heating and dissolving ultrahigh molecular weight polyethylene in a solvent, and then extracting the solvent. And a method for producing a film-like material by stretching (also referred to as "extraction method".
See Japanese Patent No. 171 and Japanese Patent Laid-Open No. 3-105851. ), (B): Ultra-high molecular weight polyethylene powder is filled in a shape-retaining tool, sintered in a steam atmosphere heated to a temperature equal to or higher than the melting point of ultra-high molecular weight polyethylene, and then cooled to form a block-shaped product. Then, a method for producing a film-like product by cutting the block-like product to a predetermined thickness (also referred to as "cutting method", JP-A-8-77997,
See JP-A-6-126899. ) And the like.

When used as a food packaging material, a medical packaging material, etc., the cut film is safer than the ultra high molecular weight polyethylene film obtained by the above extraction method because it can be obtained substantially without using a solvent. It is preferable in terms of hygiene.
However, in the ultra high molecular weight polyethylene film obtained from the cylindrical block by the conventional cutting method, from the ultra high molecular weight polyethylene block surface layer part obtained immediately after the start of cutting and the block central part at the final stage of cutting, Properties such as transparency (haze) are different from the obtained film end part, and the quality of the obtained cutting film (swive film), especially transparency is not constant (uniform), due to the site of the ultra-high molecular weight polyethylene block. There were problems such as. Further, when a flat block is produced by a conventional cutting method and the block is cooled, the block folds into a corrugated plate, and a cutting film having a uniform thickness cannot be obtained.

[0006] The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems. For example, it is found that such a difference in the quality of the skive film is caused by the cut portion from the cylindrical block. Sometimes the cooling rate of the surface layer is higher than that of the inside of the cylindrical block, so the crystallinity of the surface layer is low and the density is low, and the inside has a high crystallinity and a high density. It was thought that the skive film obtained from the surface portion of the columnar block would be more transparent than that obtained from the inner layer portion of the block.

Then, as a result of further intensive studies, it has been found that an ultrahigh molecular weight polyethylene composition obtained by blending such an ultrahigh molecular weight polyethylene with an organic peroxide (and, if necessary, a heat stabilizer) is used. In the film obtained by cutting out from the obtained ultra high molecular weight polyethylene block, for example, a corrugated plate-like fold does not occur even when cooled in a plate-shaped block, and in a columnar block, a cut-out portion from the block is formed. Therefore, the quality such as transparency becomes more constant, the wear resistance is excellent, and the quality such as transparency is constant regardless of the cut part from the block (thick molded body).
Suitable for applications such as food packaging materials, medical packaging materials, sliding tapes, laminated films with steel plates and other materials,
As a result, the present invention has been completed.

Incidentally, Japanese Patent Publication No. Sho 63-30936 uses as a final product as it is as a material for bearings, gears, roller guide rails, timing screens, etc., which are required to have self-lubricating property, low friction coefficient and wear resistance. The present invention relates to a method for producing a rod-shaped or pipe-shaped ultra high molecular weight polyethylene sintered body.
Average molecular weight by viscosity method is 1,000,000 or more, 3 by light scattering method
A mixture of 0.004 to 0.2 parts by weight of an organic peroxide and 0.5 to 10 parts by weight of a lubricant was added to 100 parts by weight of ultra high molecular weight polyethylene powder of, 000,000 or more, and the dispersed mixture was subjected to ram extrusion molding. A method for producing an ultrahigh molecular weight polyethylene sintered body that is molded into a rod-shaped sintered body is described, and according to the method for producing an ultrahigh molecular weight polyethylene sintered body described in the publication, sag (maximum diameter and minimum diameter Is very small)
It is described that a round rod-shaped or pipe-shaped ultra-high molecular weight polyethylene sintered body having a high roundness can be obtained.

Further, in the publication, as an organic peroxide which is a cross-linking agent, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane (trade name "Perhexa 25B
-40 ”manufactured by Nippon Oil & Fats Co., Ltd. and the like. However, as described above, the publication is used as a final product as a material for bearings, gears, etc.
The present invention relates to a method for producing a round bar-shaped or pipe-shaped ultra-high-molecular-weight polyethylene sintered body. As described above, it does not relate to a method for producing an ultrahigh molecular weight polyethylene sintered body film by peeling (shading) a film in a spiral shape in the circumferential direction of the sintered body toward a core.

Therefore, as a matter of course, in this publication,
When a film is made from a round bar-shaped or pipe-shaped ultra-high molecular weight polyethylene sintered body by the above "Katsura peeling", the ultra-high molecular weight of uniform quality such as haze (haze value) at the start and end of peeling There is no description or suggestion of how to obtain a polyethylene sintered body film.

Further, Japanese Patent Publication No. Sho 64-7615 relates to a resin composition for forming sliding parts such as bearings, which has the same application as that of the above-mentioned publication, in which the viscosity method is used. 100 to 100 parts by weight of ultrahigh molecular weight polyethylene powder having an average molecular weight of 1,000,000 or more and an average molecular weight of 3,000,000 or more by a light scattering method, 20 to 100 parts by weight of a pulverized product of a sintered body of ultrahigh molecular weight polyethylene and 0.0
An ultrahigh molecular weight polyethylene resin composition containing 04 to 0.2 parts by weight is described, and a press-molded article made of the composition has a low wear amount, a high limit PV value, and a relatively low dynamic friction coefficient. It is described that it has, and can be used as a sliding material that requires abrasion resistance. Examples of the crushed product of the sintered body include those having an average particle size of 1 to 10 mm and not crosslinked with an organic peroxide.

However, this publication also intends to use the obtained press-molded product as it is, and the press-molded product is spirally wound in the circumferential direction of the sintered body, such as so-called "peeling of radish". It does not relate to a method for producing an ultrahigh molecular weight polyethylene sintered body film by peeling (shaving) a film shape toward the core. Therefore, as a matter of course, in this publication, when a film is produced from a rod-shaped or pipe-shaped ultra high molecular weight polyethylene sintered body by so-called "Katsura peeling", the haze (haze) at the beginning and the end of peeling No description or suggestion is made as to how to obtain an ultra high molecular weight polyethylene sintered body film having a constant quality such as (value).

[0013]

It is an object of the present invention to solve the problems associated with the prior art as described above, and to improve abrasion resistance when a film is produced from an ultra high molecular weight polyethylene molded product by a cutting method. Excellent, quality such as transparency is constant, regardless of whether the film is cut from the ultra-high molecular weight polyethylene thick block (block) immediately after starting film cutting or at the end of the film just before the end of film cutting. Ultrahigh molecular weight polyethylene resin composition for cutting film such that ultrahigh molecular weight polyethylene film is obtained, thick-walled molded product for cutting film, and method for producing ultrahigh molecular weight polyethylene cutting film using the composition, and obtained by the production method The purpose is to provide a cutting film.

[0014]

SUMMARY OF THE INVENTION An ultrahigh molecular weight polyethylene resin composition for cutting film according to the present invention comprises an ultrahigh molecular weight polyethylene having an intrinsic viscosity [η] of 5.0 to 35 dl / g measured in decalin at 135 ° C. and an organic peroxide. It is characterized by containing an oxide. Thick-walled molded product for cutting film according to the present invention (ultra high molecular weight polyethylene block for cutting film)
Is formed by molding the above ultrahigh molecular weight polyethylene resin composition.

The method for producing an ultra high molecular weight polyethylene film according to the present invention comprises forming an ultra high molecular weight polyethylene resin composition containing ultra high molecular weight polyethylene, an organic peroxide and, if necessary, a heat stabilizer. The ultra-high molecular weight polyethylene resin thick-walled molded product (block for cutting film) thus obtained is cut to produce a film.

According to the present invention, when a film is produced from an ultrahigh molecular weight polyethylene thick-walled molded product (block) by a cutting method, it is excellent in abrasion resistance, and the film tip portion obtained by cutting from the block surface is , Ultra-high molecular weight for cutting film such as ultra-high-molecular-weight polyethylene cutting film that has constant quality such as transparency regardless of the cut-out part such as the film end part obtained from the center of the block Provided are a polyethylene resin composition, a thick-walled molded product for a cutting film, a method for producing an ultrahigh molecular weight polyethylene cutting film using the composition, and a cutting film obtained by the method.

[0017]

DETAILED DESCRIPTION OF THE INVENTION The ultrahigh molecular weight polyethylene resin composition for cutting films according to the present invention and the method for producing an ultrahigh molecular weight polyethylene cutting film using the composition will be specifically described below. <Ultra high molecular weight polyethylene resin composition for cutting film>
The ultrahigh molecular weight polyethylene resin composition for cutting films according to the present invention (simply referred to as a composition) is 1% in decalin.
The intrinsic viscosity [η] measured at 35 ° C. is 5.0 to 35 dl /
g, more preferably 8.0 to 35 dl / g ultra high molecular weight polyethylene, and an organic peroxide.

[Ultra High Molecular Weight Polyethylene] The ultra high molecular weight polyethylene used in the present invention has an intrinsic viscosity [η] of 5.0 as measured in decalin at 135 ° C. as described above.
~ 35dl / g, more preferably 8.0-35dl / g
g is preferable. Moreover, in the present invention, among such ultra-high molecular weight polyethylenes, those having an average molecular weight of 3,000,000 or more by the light scattering method are preferable. When ultrahigh molecular weight polyethylene having such a molecular weight is used, as described in JP-B-64-7615, ordinary polyethylene, that is, the average molecular weight by the viscosity method is up to about 30,000 and the light scattering is obtained. The average molecular weight by the method is about 6
There is a tendency that a cutting film excellent in various properties such as abrasion resistance, low temperature characteristics, impact resistance, and resistance to stress cracking properties can be obtained as compared with those up to about 100,000.

Such ultra-high molecular weight polyethylene comprises ethylene as a main component (in the maximum amount of all copolymerization components), and for example, a homopolymer of ethylene, ethylene as a main component and ethylene Examples thereof include copolymers with other monomers copolymerizable with ethylene. Examples of the monomer copolymerizable with ethylene include α-olefins having 3 or more carbon atoms.

Examples of the α-olefin having 3 or more carbon atoms include propylene, 1-butene, isobutene, 1
-Pentene, 2-methyl-1-butene, 3-methyl-1
-Butene, 1-hexene, 3-methyl-1-pentene,
4-methyl-1-pentene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1
-Hexadecene, 1-octadecene, 1-icosene and the like.

This ultra high molecular weight polyethylene has an intrinsic viscosity [η] of 5.0 to 35.
0 dl / g, preferably the intrinsic viscosity [η] is 8.0 to 3
It is preferably 5.0 dl / g. When the intrinsic viscosity of the ultra high molecular weight polyethylene used is within such a range, the friction and wear characteristics and the processability tend to be excellent. As such ultra-high molecular weight polyethylene, those marketed include, for example, trade names “HIZEX Million” and “Million 340M” (Mitsui Chemicals, Inc.)
Manufactured by Hoechst) and “Hostalen GUR” (manufactured by Hoechst).

[Organic Peroxide] As the organic peroxide (organic peroxide cross-linking agent), an organic substance that contributes to the cross-linking of the polyethylene and has an atomic group —O—O— in the molecule can be used without limitation. , Organic peroxides such as dialkyl peroxides, diacyl peroxides, hydroperoxides, and ketone peroxides; organic peresters such as alkyl peresters; and peroxydicarbonates.

Specific examples of the organic peroxide include dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane and 2,5- Dimethyl-2,5-di-
(Tert-Butylperoxy) hexyne-3,1,3
-Bis (tert-butylperoxyisopropyl) benzene, 1,1-bis (tert-butylperoxy)
-3,3,5-trimethylcyclohexane, n-butyl-
4,4-bis (tert-butylperoxy) valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butylperoxybenzoate, ter
Examples thereof include t-butyl perbenzoate, tert-butyl peroxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, and tert-butyl cumyl peroxide.

Among these, Japanese Examined Patent Publication No. Sho 63-30936
2,5-dimethyl-2,5-, which is an organic peroxide described in Japanese Patent Publication No. 64-7615, etc.
Bis (t-butylperoxy) hexane (trade name "Perhexa 25B" manufactured by NOF CORPORATION), 2,5-dimethyl-2,5-bis (t-butyloxy) hexyne-3 (trade name "Perhexin 25B") Nippon Oil & Fats Co., Ltd., dicumyl peroxide, and 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane are preferable.

These organic peroxides can be used alone or in combination of two or more. Such an organic peroxide is usually 0.005 to 0.3 parts by weight, preferably 0.01 to 0.2 parts by weight, and more preferably 100 parts by weight of the ultrahigh molecular weight polyethylene resin for cutting film. Is preferably contained in an amount of 0.03 to 0.15 parts by weight.

When the above composition contains the organic peroxide in such an amount, a thick-walled molded product having a uniform crystallinity regardless of the site can be obtained, and the obtained cutting film can be obtained. Has a certain degree of transparency irrespective of the cut portion from the thick molded body (block), and has excellent wear resistance (sand wear loss amount) and friction resistance characteristics (sliding property, limit PV value), and These characteristics tend to be excellent with good balance.

[Other Components] The ultrahigh molecular weight polyethylene resin composition for cutting films of the present invention (also simply referred to as “composition”) contains components other than the above components within the range not deviating from the object of the present invention. The "other component (optional component)" as contained in a normal ultra-high molecular weight polyethylene cutting film or an ultra-high molecular weight polyethylene resin composition for a cutting film may be contained.

Examples of such "other components" include heat-resistant stabilizers, reinforcing agents, extenders, lubricants, ultraviolet absorbers, antistatic agents, flame retardants, coloring agents for plastics, fungicides for plastics, Crystal nucleating agents, antioxidants, plasticizers and the like can be mentioned. [Heat-resistant stabilizer] The heat-resistant stabilizer also has a function as an antioxidant, a crosslinking modifier for ultra-high molecular weight polyethylene, and the like. As such a heat-resistant agent, JP-A-9-31336 [0047] to [0054] stage or JP-A-9-7
1728 publications [0046] to [0056], which are the heat resistance stabilizers such as phenol heat resistance stabilizers, phosphite heat resistance stabilizers, sulfur heat resistance stabilizers, amine heat resistance stabilizers;
Can be widely used.

Examples of the reinforcing agent include aluminum silicate, talc, glass fiber, metal powder and the like. As the extender, a general-purpose resin such as polyethylene can be used in addition to calcium carbonate and silica. Examples of the lubricant include powders of montanic acid ester wax and fatty acid derivative wax (eg, dicarboxylic acid ester, glycerin fatty acid ester, amide wax, etc.).

<Manufacturing of Cutting Film> Next, a method of manufacturing a cutting film using the above ultrahigh molecular weight polyethylene resin composition for cutting film will be described. In the present invention, an ultrahigh molecular weight polyethylene resin composition (resin composition) containing the above-described ultrahigh molecular weight polyethylene, an organic peroxide (and optionally a heat stabilizer) is molded,
Preferably, press molding or extrusion molding is performed to obtain the obtained ultra-high molecular weight polyethylene resin thick-walled molded product (resin block for cutting film), and from this block, the ultra-high molecular weight polyethylene cutting film (simply cut It is also called film, film, etc.).

In the present specification, "thick-walled molded product"
Means that when the ultra-high-molecular-weight polyethylene resin composition is heated and compression-molded and then cooled to produce a molded body (block) for cutting, the cooling rate varies to the extent that the degree of crystallinity varies depending on the site. A molded product having a thickness, for example, when the shape is a plate, the thickness is usually 3 cm.
(Thickness) The above can be mentioned, and in the case of a cylindrical object, the cross-sectional radius is, and in the case of a cylindrical object, the wall thickness, that is, the cross-sectional outer diameter is R ² , and the inner diameter is R ¹ , then “(R ² −R ¹⁾ / 2 (where R ^2: outer diameter, R ^1: inside diameter) "is the same range as in the case of the plate-like thereof.

(Ultra high molecular weight polyethylene for cutting film
Preparation of Resin Composition) In detail, in a preferred embodiment of the present invention, the above ultrahigh molecular weight polyethylene powder (a) is used.
And the organic peroxide cross-linking agent (b), relative to 100 parts by weight of polyethylene (a), the cross-linking agent (b) is usually 0.005 to 0.3 parts by weight, preferably 0.01. ~
0.2 parts by weight, more preferably 0.03 to 0.15 parts by weight, are mixed and stirred and mixed.

In particular, the average particle size of the ultrahigh molecular weight polyethylene powder (a) is usually 10 to 600 μm, preferably 10 to 350 μm, and more preferably 25 to 350.
When it is in the range of μm, the resulting ultrahigh molecular weight polyethylene resin composition block for cutting film tends to have uniform physical properties such as transparency (crystallinity) regardless of the site.

The stirring / mixing conditions vary depending on conditions such as temperature, pressure, stirring speed, etc., and are not generally determined. For example, at room temperature and normal pressure, 50 rpm / min to 80 rpm.
The mixture may be stirred and mixed at a speed of 0 revolutions / minute for about 1 minute to 10 minutes. The stirring / mixing speed may be appropriately changed. For example, stirring may be initially performed at a low speed for several minutes, and when the ingredients are uniformly mixed to some extent, the stirring / mixing may be performed at a higher speed for several minutes.

For stirring and mixing, a Henschel mixer or the like which is generally used is used. In addition,
The above-mentioned "other components" added as necessary can be added and mixed at any time, and for example, may be added at the time of mixing and stirring the polyethylene (a) and the cross-linking agent (b).
The "other components" may be added and mixed with the polyethylene (a) or the crosslinking agent (b), and the "other components" may be added and mixed with the obtained "polymer / crosslinking agent mixture".

(Molding) Next, in the present invention, the ultrahigh molecular weight polyethylene resin composition for cutting film (also simply referred to as “resin composition”) obtained as described above is molded. The ultra high molecular weight polyethylene contained in such an ultra high molecular weight polyethylene resin composition does not substantially melt and is not suitable for melt molding like ordinary thermoplastic resins (eg polyethylene). As a method for molding the composition, a polytetrafluoroethylene resin (PTFE) is molded, a sintering molding method which is a processing method, a compression molding method, a ram extrusion molding method (see JP-B-63-30936), and a paste extrusion molding. Method, screw extrusion molding method, etc. can be appropriately used.

In order to form a block by molding the above resin composition by a sinter molding method, for example, first, the ultrahigh molecular weight polyethylene resin composition for a cutting film is compression molded and then solidified by cooling. . Compression molding The compression molding can be carried out in two stages of the following "preforming" (a) and subsequent "main molding" (b).

(A) Preforming In the present invention, it is preferable to perform air venting from the object to be treated prior to the main forming (b). Pre-molding is performed by placing the ultra high molecular weight polyethylene resin composition for a cutting film in a mold having a desired shape such as a cylindrical shape or a box shape, sealing the mold, and heating the mold from the outside of the mold. The ultrahigh molecular weight polyethylene resin composition for cutting film filled therein is below the melting point of the polyethylene resin contained therein, preferably at a temperature of "melting point -10" C, room temperature to 130C, preferably 80 to 100C. Under normal pressure to under pressure (example:
500 kg / cm ² ), preferably 100-300 kg
It is desirable to carry out the treatment under a pressure of / cm ² for usually 10 minutes to 120 minutes, preferably 20 minutes to 60 minutes.

When preformed under such conditions, the block which is the preformed product (preform) and the cutting film which is the final product obtained have a small void amount and tend to have high strength. (B) Main forming (sintering) In order to perform main forming after preforming, the temperature and pressure conditions are usually changed continuously or discontinuously from the preforming condition to the main forming condition in the same mold. .

To continuously change the temperature, pressure, etc. from the preforming condition to the main forming condition, for example, the forming temperature is continuously raised from the preforming temperature to a higher main forming temperature, and the pressing pressure is increased. Etc. by adjusting the preforming pressure,
The pressure may be continuously reduced to a lower main forming pressure. The main molding is carried out at a temperature not lower than the melting point of the polyethylene resin contained and lower than the decomposition temperature, preferably 160 to 250 ° C, which is "melting point +30" ° C to "decomposition temperature -100" ° C, and more preferably 180 to 210 ° C. , Pressure 10-200kg
/ Cm ² , preferably 50 to 120 kg / cm ² under, 2
The ultra-high molecular weight polyethylene particles may be sintered by heating for 0 minutes to 10 hours, preferably 30 minutes to 9 hours (sinter molding method).

Next, the ultra high molecular weight polyethylene resin composition (sintered body) thus sintered is cooled and solidified. Cooling and solidifying Cooling is performed on the sintered body obtained as described above, for example,
It can be carried out by holding in the mold under the above-mentioned pressure conditions and usually from the above-mentioned main molding temperature to room temperature by forced cooling or naturally leaving it, usually 0.1 to 70 ° C./min.
Preferably 0.5 to 10 ° C./min, usually 3 to 24 hours,
It is preferably carried out by lowering the temperature and cooling over about 5 to 15 hours. The pressure condition and the cooling / cooling rate may be changed stepwise or continuously.

When the sintered body is cooled and solidified under such conditions, an ultra-high molecular weight polyethylene thick-walled body (also referred to as a block) having a constant crystallinity and the like regardless of the block portion is obtained. The size of a cylindrical molded body (billet), which is one type of such a block, is not particularly limited, but for example, in FIG. 2 described later, the outer diameter (2r ² ) of the cylinder is 30 to 80 cm, preferably 30. ~ 50 cm
And the height (L) thereof is 30 to 100 cm (in the cylindrical shape, the void inner diameter 2r ¹ : 5 to 10 cm). In addition, in the present specification, unless otherwise specified, not only a columnar object (not shown) but also a cylindrical object (see FIG. 2) is collectively referred to as a billet.

(Is the ultra high molecular weight polyethylene resin block
( Cutting of the film), then main forming (sintering) in this way
Then, from the main body shaped into a desired shape such as a columnar shape or a cylindrical shape, it is peeled off in a film shape toward the core in a spiral shape in the circumferential direction of the sintered body, as in “Peeling radish”. By cutting), an ultrahigh molecular weight polyethylene sintered body cutting film (ultrahigh molecular weight polyethylene cutting film) is obtained.

The thickness, width, etc. of such an ultra-high molecular weight polyethylene cutting film differ depending on the application used and are not unconditionally determined. For example, the thickness is 50 μm to 3
mm, preferably 50-600 μm, width 30-
It is about 100 cm. The ultrahigh molecular weight polyethylene cutting film of the present invention thus obtained has a billet (density, melting point, crystallinity, tensile elastic modulus, etc. of the cutting film as compared with that without the addition of a crosslinking agent. (Cylindrical object) etc. is uniform regardless of the cutting site from the block, and is uniformly (uniformly) crosslinked. Also, the haze value of the cutting film is large regardless of the cutting site from the billet. There is no difference and it has a uniform appearance with uniform transparency.

(Uses of Cutting Film) Such a cutting film has a uniform transparency regardless of a cut portion,
It is preferably used for the following applications. For example, food packaging materials, battery separators, sliding tapes, laminated films with steel plates and other materials, and precision processing materials.

[0046]

EFFECTS OF THE INVENTION According to the present invention, when a film is produced from a UHMWPE thick-walled molded product (block) by a cutting method in this way, it is excellent in abrasion resistance and Cutting that yields an ultra-high molecular weight polyethylene cutting film with constant quality such as transparency, regardless of whether it is the film front end immediately after cutting starts or the film end just before the end of film cutting Ultra high molecular weight polyethylene resin composition for film, ultra high molecular weight polyethylene resin composition block for cutting film (thick molded product), method for producing ultra high molecular weight polyethylene cutting film using the composition and obtained by the method A cutting film having the above characteristics is provided.

[0047]

EXAMPLES The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited thereto. The samples used in the following examples and comparative examples, the stirring conditions of the test samples, the molding conditions of the ultra-high molecular weight polyethylene block (cylindrical cylinder), the evaluation method of the cutting film, etc. are as follows.

[0048]

Example 1 and Comparative Example 1 In Example 1 shown in Table 1, as a cross-linking agent, an organic peroxide “Perhexa 25B” (2,5
-A dimethyl-2,5-di (t-butylperoxy) hexane, manufactured by NOF CORPORATION, was used to prepare a thick-walled molded product for a cutting film as follows, and the method was as follows. Tested.

Comparative Example 1 was the same as Example 1 except that the crosslinking agent was not added. 1. <Sample> Base polymer: Product name "Million 340M"
(Manufactured by Mitsui Chemicals, Inc.), ultra-high molecular weight polyethylene powder [heat-resistant stabilizer-free product, average particle diameter: 150 μm, viscosity average molecular weight: 3,000,000, intrinsic viscosity [η] (measured in decalin at 135 ° C.) 21 dl / g]. Cross-linking agent: Organic peroxide (compound name: (2,5-dimethyl-2,5-di (t-butylperoxy) hexane), trade name "Perhexa 25B" (NOF Corporation)
Made, food use possible). Addition amount: 0.05 part by weight of a crosslinking agent is added to 100 parts by weight of the base polymer. 2. <Stirring conditions> Master powder containing cross-linking agent Preparation work Base polymer / cross-linking agent = 100/1 (weight ratio) Stirring (Henschel) conditions: 1 minute / low speed (500 rp)
m) Raw material stirring operation Base polymer / master powder = 95/5 (weight ratio) Stirring (Henschel) conditions: 1 minute / low speed (500 rp)
m) 3. <Billet Press (Cylindrical) Molding Condition> FIG. 1 shows a schematic vertical sectional view of a mold 20 used in “preforming” and “main forming”.

The mold 20 shown in FIG. 1 is provided on the mold body 14 having a cylindrical void 15 filled with the resin composition 18 to be molded, and on the outer peripheral portion and the core of the mold body 14. And a heating heater 16 for heating the resin composition to be molded to a predetermined temperature through heating of the mold body, and pressure presses 12A, 12 for vertically pressing the filled resin composition.
It has B and.

In the present invention, the above-mentioned mold was used to press-mold the ultrahigh molecular weight polyethylene resin composition into a cylindrical shape as shown in FIG. 2 under the following conditions. (A) Charge amount of sample (ultra high molecular weight polyethylene resin composition): 25 kg (b) Preforming: molding temperature (100 ° C.) × pressing pressure (129 kg / cm ² ) × time (1 h) (c) main molding: Molding temperature (200 ° C. outside the mold, 193 ° C. inside the mold), press pressure (58 kg / cm ² ) × time (8.5 h) (d) Cooling: Allow to cool from the molding temperature.

After holding the press pressure (85 kg / cm ² ) × time (3 h), press pressure (58 kg / cm ² ) ×
Hold for 7 hours. (E) Dimensions of cylindrical thick-walled molded product: axial length L (450c
m), the distance (radius) r from the center of the cylindrical cross section to the outer circumference
² (300 cm), void radius r ¹ (100
cm). 4. <Evaluation> A cylindrical thick molded body 30 as shown in FIG. 2 obtained by using the mold shown in FIG. 1 is divided into three equal parts at right angles to the axial direction, and is a part from the lower end to 1/3. “Lower part”, “middle part” which is a part from axial lower end to 1/3 to 2/3, and “upper part” which is a part from axial lower end to 2/3 to 3/3 (upper end) In addition to the division, also in the cross-sectional radial direction of the cylindrical thick-walled body 30, as shown in FIG. 2, the wall thickness is divided into three equal parts in the thickness direction, and is close to the central axis of the cylindrical thick-walled body (billet). The evaluation was performed by dividing into "the inner layer" which is a portion, "the surface layer" which is a portion near the outer peripheral portion, and "the central layer" which is a portion sandwiched between the inner layer and the surface layer. Solid physical properties (a) Sampling: Cutting from the bottom of the billet (3 mm ^t
(Thickness), 6 mm ^t (Thickness)) (B) Evaluation item Surface layer, central layer, inner layer: density, melting point, and crystallinity were measured.

Central layer: Tensile strength, sand wear loss, limit P
Measure V value (sliding property). The measurement results are shown in Table 1. Physical properties of the skive film As shown in FIG. 3, in the central portion of the cylindrical thick molded body 30,
A drive shaft 32 for rotating the cylindrical thick molded body 30 in the axial direction is set, and a skive cutting blade 34 is arranged so as to be parallel to the axial outer peripheral surface of the cylindrical thick molded body 30 in the axial direction.
And rotate the cylindrical thick-walled molded body in the direction of the cutting blade,
The skive film 36 was cut, and the following items were evaluated for the following parts.

(A) Sampling: skiving (0.
25 mm ^t (thickness)) (b) Evaluation items: (surface layer, central layer, inner layer) x (upper part, middle part, lower part):
Density, crystallinity (surface layer, central layer, inner layer) x (middle part): Table 2 shows the haze, internal haze, and transparency measurement results. 5. Results The results are shown in Tables 1 and 2.

[0055]

[Table 1]

(Note 1) The evaluation sample is the lower side in the axial direction of the billet (cylindrical) molded product (Note 2) ultra high molecular weight polyethylene: "340M"
(Mitsui Chemicals, Inc.) Crosslinking agent: "Per-hexa 25
B ”(manufactured by NOF CORPORATION) ... 0.05 part by weight of a crosslinking agent was added to 100 parts by weight of ultrahigh molecular weight polyethylene (no heat stabilizer was added).

The amount of the cross-linking agent added is the same as that described in the section of "Detailed Description of the Invention", that is, the wear resistance (* 1 sand wear loss amount) and the slidability (* 2 PV limit). It was carried out within the range in which the effect of (value) can be expressed. <Consideration of Table 1> According to Table 1, as shown in Example 1, the crystallinity (* 3 crystallinity) of the ultra-high molecular weight polyethylene thick-walled molded product of the present invention is It can be seen that it is uniformized regardless of the part.

[0058]

[Table 2]

<Consideration of Table 2> According to Table 2, as shown in Example 1, the crystallinity (* 1 crystallinity) of the skive film obtained from the ultra-high molecular weight polyethylene thick molded product according to the present invention ) Is Comparative Example 1
It can be seen that, compared with the above, the thickness is uniformed regardless of the part of the thick-walled molded body. Further, according to Table 2, in the skive film obtained from the ultra-high-molecular-weight polyethylene thick molded product of the present invention as shown in Example 1, as compared with Comparative Example 1, haze (* 2),
It can be seen that the internal haze (* 3) and the transparency (* 4) are also uniform regardless of the site of the thick molded product.

[Brief description of drawings]

FIG. 1 is a plan view of the thick-walled molded body of the present invention,
The schematic longitudinal cross-sectional view of the metal mold | die used for preforming and main forming is shown.

FIG. 2 is an explanatory diagram showing sampling positions of a sample for evaluation from an ultra-high molecular weight polyethylene thick-walled molded product obtained by using the mold shown in FIG.

FIG. 3 is an explanatory view showing a method for cutting a skive film from the cylindrical thick-walled molded product for cutting film (billet) shown in FIG. 2.

[Explanation of symbols]

12A, 12B ... Pressure press, 14 ・ ・ ・ ・ ・ ・ Mold body, 15 ... ・ Cylindrical cavity of the mold body, 16 ... Heating heater, 18: Ultra-high molecular weight polyethylene resin composition, 20 …… ・ Mold, 30 ··· Billet (thick molded body), 32 ··· Drive shaft, 34 ... Sky film cutting blade, 36 ... Sky film.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Suzuki Iwatoshi             Mitsui 6-1-2 Waki, Waki Town, Kuga District, Yamaguchi Prefecture             Inside Chemical Co., Ltd. F-term (reference) 4F071 AA15 AA81 AA88 AC08 AE02                       BB03 BC01 BC06                 4J002 BB031 BB051 BB151 EK036                       EK046 EK056 FD146 GG01                       GM00 GN00 GQ00

Claims (4)

[Claims] 1. An ultrahigh molecular weight polyethylene for cutting film, which comprises ultrahigh molecular weight polyethylene having an intrinsic viscosity [η] of 5.0 to 35 dl / g measured in decalin at 135 ° C. and an organic peroxide. High molecular weight polyethylene resin composition. 2. A thick-walled molded product for cutting film, which is obtained by molding the ultrahigh molecular weight polyethylene resin composition according to claim 1. 3. A film is produced by cutting from an ultrahigh molecular weight polyethylene resin thick-walled molded product obtained by molding an ultrahigh molecular weight polyethylene resin composition containing ultrahigh molecular weight polyethylene and an organic peroxide. A method for producing an ultra-high molecular weight polyethylene cutting film, which comprises: 4. A cutting film obtained by the method according to claim 3.