JPH09143318A - Method for preventing generation of dicing dust of pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of dicing dust in the production of pipe from a linear low-density ethylene/α-olefin copolymer. SOLUTION: In producing a pipe by extruding a linear low-density ethylene/α- olefin copolymer from a die, the generation of dicing dust of a pipe can be prevented by using an ethylene resin composition comprising 100 pts.wt. linear low-density ethylene/α-olefin copolymer, 0.0005-0.01 pt.wt. fluoropolymer of a molecular weight of 20,000-200,000 and optionally 0.01 pt.wt. or below poly(oxyalkylene) polymer of a molecular weight of 5,000-100,000 is used instead of the linear-low-density ethylene/α-olefin copolymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing the generation of die scum when producing a pipe made of a linear low density ethylene-α-olefin copolymer. More specifically, the present invention prevents the generation of die scum, does not adversely affect the appearance of the pipe and the inner surface of the pipe, and can give a high-quality product, an ethylene-based resin composition for pipes, and a pipe molded from the composition. Also, the present invention relates to a method for preventing the generation of dicus.

[0002]

2. Description of the Related Art In recent years, pipes made of high-pressure low-density polyethylene are not easily corroded, are lightweight, have good workability in laying, and are excellent in strength, stress crack resistance, flexibility, etc. It has been used. However,
When a high-pressure low-density polyethylene pipe is used for a long time, water bubbles are generated on the inner wall of the pipe mainly due to the effect of chlorine used for sterilizing tap water, and the inner surface of the pipe peels off to block the valve. Sometimes caused trouble. In order to solve this problem, a linear low-density ethylene-α-olefin copolymer having high resistance to chlorine-containing water and having the same performance as that of the high-pressure process low-density polyethylene is suitable for tap water. It has been used as a pipe. However, when a linear low-density ethylene-α-olefin copolymer is extruded from a die of an extruder and a pipe is manufactured, a geiscus is generated at the die outlet, which adheres to the surface of the extruded pipe, Had a bad effect on the appearance and inner surface of the pipe, the pipe deviated from the standard size, and the performance of the pipe deteriorated. The cause of the above-mentioned dicus is the influence of the catalyst residue used in polymerizing the copolymer, the influence of the low molecular weight substance in the copolymer, the effect of carbon black, an additive such as a stabilizer or an antioxidant, Alternatively, the influence of water adsorbed on the above copolymer may be considered.

[0003]

As described above, when a pipe made of a linear low-density ethylene-α-olefin copolymer is produced and die scum is generated, the appearance of the pipe and the inner surface of the pipe are deteriorated. Therefore, it is an object of the present invention to provide a method for preventing the generation of die scum because a high quality pipe cannot be obtained. Another object of the present invention is to provide an ethylene resin composition for pipes which can prevent the generation of die scum as described above, and a pipe produced from the composition.

[0004]

Means for Solving the Problems The present inventor has paid attention to the relationship between the cause of the above-mentioned die scum and the adhesiveness to the die,
When we tried to mix various dispersants, lubricants, metal surface deactivators, gel preventives, etc., when we added a specific amount of one or two specific additives, we found an excellent effect in preventing the generation of die scum. The present invention has been completed and further studies have been completed to complete the present invention.

That is, according to the present invention, when a linear low-density ethylene-α-olefin copolymer is extruded from a die to manufacture a pipe, 100 parts by weight of the linear low-density ethylene-α-olefin copolymer is used. For a molecular weight of 20,000
˜200,000 fluoropolymer 0.0005 to 0.
The present invention relates to a method for preventing the generation of die scum in pipes, which is characterized by adding 01 part by weight.

The present invention also relates to linear low density ethylene-α.
-When an olefin copolymer is extruded from a die to produce a pipe, a molecular weight of 20,000 to 20 is added to 100 parts by weight of a linear low-density ethylene-α-olefin copolymer.
The present invention relates to a method for preventing the generation of a die scum of a pipe, which comprises blending 0.0005 to 0.01 part by weight of a fluorinated polymer of 0000 and 0.01 part by weight or less of a poly (oxyalkylene) polymer having a molecular weight of 5,000 to 100,000.

The present invention further includes linear low density ethylene-
100 parts by weight of α-olefin copolymer and molecular weight of 200
Fluorine-based polymer 0.0005 to 200,000
0.01 parts by weight of the ethylene-based resin composition for pipes.

The present invention also relates to linear low density ethylene-
100 parts by weight of α-olefin copolymer and molecular weight of 200
Fluorine-based polymer 0.0005 to 200,000
The present invention relates to an ethylene resin composition for pipes, which comprises 0.01 parts by weight and 0.01 parts by weight or less of a poly (oxyalkylene) polymer having a molecular weight of 5,000 to 100,000.

Further, the present invention relates to a pipe, characterized in that any one of the above-mentioned ethylene resin compositions for pipes of the present invention is extruded and molded from an extruder.

The linear low density ethylene-α-olefin copolymer used in the present invention is a copolymer of ethylene and an α-olefin, for example, an α-olefin having 3 to 12 carbon atoms. Specific examples of the α-olefin include propylene, butene-1, hexene-1, 4-methylpentene-1, octene-1, decene-1, dodecene-1, and the like. Examples of catalysts that can be used during the polymerization of the ethylene-α-olefin copolymer include Ziegler-based catalysts and Phillips-based catalysts. The Ziegler type catalyst is composed of a main catalyst composed of a transition metal compound such as a titanium compound or a vanadium compound, a co-catalyst composed of an organometallic compound such as an organoaluminum, and a catalyst carrier composed of an oxide or a chloride such as silicon, titanium or magnesium. It is what is done. The Phillips catalyst is composed of a main catalyst composed of chromium oxide and a catalyst carrier composed of oxides of silicon, aluminum and the like. For the polymerization, a solution polymerization method, a suspension polymerization method, a slurry polymerization method, a gas phase polymerization method or the like can be used. The temperature during the polymerization is 0 to 250 ° C, and the pressure is high (50
MPa or higher), medium pressure (10 to 50 MPa) or low pressure (normal pressure to 10 MPa).

The above-mentioned linear low density ethylene-α-olefin copolymer has the following physical properties: melt flow rate 0.1 g to 5 g / 10 minutes and density 0.91 to 0.93.
Those having g / cm ³ are preferred. Here, the melt flow rate is measured according to JIS K7210,
If it is less than 0.1 g / 10 minutes, the extrusion load will be too large when extruding with an extruder and molding will be difficult, and if it exceeds 5 g / 10 minutes, the extrusion moldability will be poor and the mechanical properties will be poor. Is inferior in physical properties, which is not preferable. Further, the density is measured according to JIS K7112 and is 0.91 g /
If it is less than ³ cm ³ , the obtained product becomes sticky, which is not preferable, and if it exceeds 0.93 g / cm ³ , flexibility, elongation, impact resistance, etc. are deteriorated, which is not preferable.

The fluoropolymer used in the present invention means tetrafluoroethylene, trifluoroethylene chloride, vinylidene difluoride, ethylene monofluoride, propylene hexafluoride, vinyl ether containing fluorine, ethylene, propylene,
It is a copolymer obtained by copolymerizing two or more kinds of monomers selected from perfluoropropylene and the like.

As an example of the fluoropolymer in the present invention, a vinylidene fluoride-hexafluoropropylene copolymer [eg Fluorel (trade name) manufactured by 3M,
Duton's Viton A (trade name), Monte Edison's Technoflon (trade name), Daikin's Dai-El (trade name), etc.], vinylidene fluoride-
Hexafluoropropylene-tetrafluoroethylene copolymer [for example, Viton B (trade name) manufactured by DuPont, Dai-ElG-501 (trade name) manufactured by Daikin Co., Ltd.], tetrafluoroethylene-propylene copolymer [for example, Asahi Glass Co., Ltd. Made of Aflas100, Aflas
150 (both trade names) and the like], vinylidene fluoride-chlorotrifluoroethylene copolymer [eg, Kel manufactured by 3M Co., Ltd.
F-3700 (trade name), etc., vinylidene fluoride-1-
Hydropentafluoropropylene copolymer [for example, Technoflon SL (trade name) manufactured by Monte Edison Co., Ltd.], vinylidene fluoride-1-hydropentafluoropropylene-tetrafluoroethylene copolymer [for example, Technoflon T (manufactured by Monte Edison Co., Ltd. Product name, etc.] and the like.

The molecular weight of the fluoropolymer is 20000
The range is 200,000. If it is less than 20,000, die scum is likely to occur, and if it exceeds 200,000,
The compatibility with the linear low-density ethylene-α-olefin copolymer is poor and, as a result, die scum easily occurs, which is not preferable.

The poly (oxyalkylene) polymer selectively used in the present invention means ethylene oxide,
Propylene oxide, a polymer having a polymerized unit such as butylene oxide, the terminal group is an alkyl group,
Alkoxy group, aromatic hydrocarbon group, hydroxyl group, acyl group,
Those selected from hydrogen atoms and the like, polyethylene glycol, polyethylene oxide, polyethylene glycol fatty acid ester, polyoxyalkyl allyl ether, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylphenyl ether sulfate, Polyoxyethylene higher fatty acid alcohol, polyoxyethylene fatty acid alcohol ether, polyoxyethylene fatty acid amide, polyoxyethylene fatty acid ester, polyoxyethylene stearol ether, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbit fatty acid ester, polyoxyethylene Secondary alcohol ether, polyoxyethylene polyoxypropylene block copolymer, Polyoxyethylene lanolin derivatives, polyoxymethylene glycols, polyoxymethylene, polytetramethylene ether glycol, polypropylene glycol, polypropylene oxide, polybutylene glycol, polybutylene oxide, polyoxyethylene polyoxybutylene block copolymer, and the like.

The molecular weight of the poly (oxyalkylene) polymer is in the range of 5,000 to 100,000, preferably 10,000 to 30,000. When it is less than 5,000, thermal stability is poor and bleeding easily occurs on the surface of the pipe, which is not preferable, and when it exceeds 100,000, dispersibility is poor and it is not preferable.

In the present invention, the fluorine-based polymer is blended in an amount of 0.0005 to 0.01 part by weight based on 100 parts by weight of the linear low-density ethylene-α-olefin copolymer.
If it is less than 0.0005 parts by weight, the effect of preventing die scum is not obtained, and if it exceeds 0.01 parts by weight, streaks are generated on the inner surface of the pipe, too much gloss is produced, and it is not preferable.

In the present invention, the poly (oxyalkylene) polymer is blended in an amount of 0.01 parts by weight or less based on 100 parts by weight of the linear low-density ethylene-α-olefin copolymer. If it exceeds 0.01 parts by weight, streaks are generated on the inner surface of the pipe, too much gloss is produced, and it is sticky, which is not preferable.

In the present invention, in addition to the above-mentioned essential components, various additives and auxiliary materials can be added depending on the purpose of use, as long as the characteristics of the present invention are not impaired. As various additives and auxiliary materials, stabilizers, antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, cross-linking agents, lubricants, processability improving agents, fillers, dispersants, neutralizing agents, anti-foaming agents. Agents, colorants, carbon black and the like.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the fluoropolymer and the poly (oxyalkylene) polymer are
Ethylene resin for pipes, which is blended with a linear low-density ethylene-α-olefin copolymer, uniformly mixed and kneaded with a kneader, Banbury mixer, continuous mixer, extruder, etc., and granulated. A composition is produced and the composition can be fed to a pipe extruder.

In the present invention, the method for molding the ethylene resin composition for pipes of the present invention into a pipe is to extrude the composition at a temperature of 150 to 230 ° C. from an extruder through a die and perform sizing, Examples include a method of cooling in a cooling water tank and cutting or winding through a take-up machine. The pipe can be a single layer pipe or a two layer pipe. Examples of the extruder include a single screw extruder. Any type of die such as a straight head die, a cross head die, and an offset die can be used. As the sizing method, any of a sizing plate method, an outside mandrel method, a sizing box method, an inside mandrel method and the like can be used.

[0022]

The present invention will be described in more detail based on the following examples, but the present invention is not limited to these examples without departing from the gist of the present invention.

Example 1 Linear low density ethylene-butene-1 copolymer (density 0.
92 g / cm ³ , melt flow rate 0.7 g / 10
Min, manufactured by Nippon Unicar Co., Ltd., manufactured by the Unipol method), 0.0009 parts by weight of a fluoropolymer having a molecular weight of 70,000 (manufactured by DuPont, trade name: Viton A) and polyethylene glycol having a molecular weight of 20,000 (NOF Corporation). Product name: Nissan polyethylene glycol #
20000) 0.0021 parts by weight was blended and kneaded in a Banbury mixer at a temperature of 150 ° C. for 10 minutes, and then pellets were obtained by using the pellets obtained by granulation.

The above pellet was 65 mm, L / D = 25
Melted at a temperature of 170 ° C using a single-screw extruder with a discharge rate of 65 kg / hour and a nominal diameter of 20 mm
9.2 mm), extruded from a straight spiral die with a gap of 8.3 mm, controlled the outer diameter by sizing the outer diameter, cooled and drawn at a take-up speed of 4 m / min to form a pipe with an outer diameter of 27 mm and a wall thickness of 4 mm processed. The generation of dicus is not recognized even after 50 hours have passed since the start of operation,
The appearance of the pipe and the inner surface of the pipe were good.

Example 2 In Example 1, the blending amount of the fluoropolymer was 0.0
When the same experiment as in Example 1 was carried out except that the amount was set to 05 parts by weight and polyethylene glycol was not mixed, the generation of die scum was not observed even after 75 hours from the start of operation, and the appearance of the pipe and the pipe The inner surface of each was good.

Example 3 In Example 1, the blending amount of the fluoropolymer was 0.0
When the same experiment as in Example 1 was carried out except that the amount was 01 parts by weight and polyethylene glycol was not blended, a small amount of die scum was generated 50 hours after the start of operation, but the appearance of the pipe and the inner surface of the pipe were adversely affected. It wasn't enough.

Comparative Example 1 In Example 1, the blending amount of the fluoropolymer was 0.0
An experiment similar to that of Example 1 was carried out except that the amount was decreased to 003 parts by weight. As a result, die scum was generated several hours after the start of operation, and thereafter, the die scatter increased in large amounts, and both the appearance of the pipe and the inner surface of the pipe were increased. Had a bad effect on.

Comparative Example 2 In Example 1, the amount of the fluorine-containing polymer compounded was 0.0
The same experiment as in Example 1 was carried out except that the amount of polyethylene glycol was 15 parts by weight and the amount of polyethylene glycol was 0.015 parts by weight. Was produced too much, and moreover, the surface of the pipe was sticky.

COMPARATIVE EXAMPLE 3 In Example 1, the fluorine-based polymer was used in a molecular weight of 1000.
An experiment similar to that of Example 1 was carried out except that the number of die was changed to 0, die scum was generated within a few hours after the start of operation, and thereafter, the die scatter increased in large quantities, and both the appearance of the pipe and the inner surface of the pipe were increased. Had a bad effect on.

Comparative Example 4 In Example 1, the fluorine-based polymer was added to a molecular weight of 2,500.
An experiment similar to that of Example 1 was conducted except that the number of 00 was changed, and die scum was generated within several hours after the start of operation.
After that, the amount of die scum increased in a large amount, which adversely affected both the appearance of the pipe and the inner surface of the pipe.

Comparative Example 5 In Example 1, polyethylene glycol was added with a molecular weight of 3
An experiment similar to that of Example 1 was performed except that the number of die was changed to 000, and die scum was generated within a few hours after the start of operation. Had a bad effect on.

Comparative Example 6 In Example 1, polyethylene glycol was used with a molecular weight of 1
An experiment similar to that of Example 1 was carried out except that the number of die was changed to 50000, and die scum was generated several hours after the start of operation. Had a bad effect on.

[0033]

As described above in detail, in the present invention, a specific fluorine-containing polymer is specified in the production of a pipe made of a linear low-density ethylene-α-olefin copolymer which easily causes die scum. By mixing in a certain amount or by mixing a specific fluorine-based polymer and a specific poly (oxyalkylene) polymer respectively, it is possible to remarkably suppress the generation of die scum during the pipe forming process, and the appearance of the pipe and the inner surface of the pipe. It is possible to effectively maintain the temperature of the pipe, manufacture a pipe of excellent quality continuously for a long time, and reduce the cost.

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Claims (5)

[Claims] 1. When a linear low-density ethylene-α-olefin copolymer is extruded from a die to produce a pipe,
Linear low density ethylene-α-olefin copolymer 100
A method for preventing the generation of die scum in a pipe, which comprises blending 0.0005 to 0.01 part by weight of a fluoropolymer having a molecular weight of 20000 to 200,000 with respect to parts by weight. 2. When a linear low-density ethylene-α-olefin copolymer is extruded from a die to produce a pipe,
Linear low density ethylene-α-olefin copolymer 100
A pipe characterized by blending 0.0005 to 0.01 part by weight of a fluoropolymer having a molecular weight of 20,000 to 200,000 and 0.01 part by weight or less of a poly (oxyalkylene) polymer having a molecular weight of 5,000 to 100,000 with respect to parts by weight. To prevent the occurrence of die scum. 3. A linear low-density ethylene-α-olefin copolymer (100 parts by weight) and a molecular weight of 20000-2000.
And 0.0005 to 0.01 part by weight of a fluoropolymer of No. 00, an ethylene resin composition for pipes. 4. A linear low-density ethylene-α-olefin copolymer (100 parts by weight) and a molecular weight of 20,000 to 2,000.
An ethylene resin composition for pipes, which comprises 0.0005 to 0.01 part by weight of a fluorinated polymer of 00 and 0.01 part by weight or less of a poly (oxyalkylene) polymer having a molecular weight of 5,000 to 100,000. 5. A pipe produced by extruding the ethylene resin composition for pipe according to claim 3 or 4 from an extruder.