WO1999037458A1

WO1999037458A1 - Process for producing molded tetrafluoroethylene polymer

Info

Publication number: WO1999037458A1
Application number: PCT/JP1999/000172
Authority: WO
Inventors: Osamu Shirasaki; Shingo Tanigawa
Original assignee: Daikin Industries, Ltd.
Priority date: 1998-01-22
Filing date: 1999-01-20
Publication date: 1999-07-29
Also published as: JPH11207812A

Abstract

A process for producing a molded polytetrafluoroethylene polymer which comprises: disposing molded polytetrafluoroethylene polymer parts each having one or more areas where the parts are to be bonded to each other, along or near the inner wall of a mold; disposing a cylindrical molded polytetrafluoroethylene polymer part having an area where it is to be bonded to those molded parts, at a through hole formed in the mold; and heating the molded parts and the cylindrical molded part to a temperature not lower than the melting point of the polytetrafluoroethylene polymer while rotating the mold containing the molded parts and the cylindrical molded part to thereby bond all these parts at their bonding areas to form a united molded article having an outer shape conforming to the inner wall of the mold. Thus, a molded polytetrafluoroethylene polymer can be produced in which the parts have been evenly and tenaciously united with each other at the bonding areas, the inner surface has no projection or depression and is smooth, and the cylindrical projecting part has been tenaciously bonded to the main body of the molded article.

Description

Specification

Method for producing tetrafluoroethylene polymer molded article

TECHNICAL FIELD The present invention relates to a method for producing a tetrafluoroethylene-based polymer-joined molded article, and more particularly, to a mold for rotating two or more molded parts of a tetrafluoro / rheo-ethylene polymer. The present invention relates to a method for producing a tetrafluoroethylene-based polymer bonded molded article, which comprises bonding and integrating the bonded surfaces at the bonding surface while heating the inside.

Background art

As one method of manufacturing a modified PTFE molded article, a method of heat-pressing two or more modified PTFE molded parts to each other is known. (Hostaflon 'Information published by Hoechst AG) Hostaflon Information) 21 (August 1983). However, this method requires a smooth surface to be crimped. In addition, it is necessary to set the molded part horizontally during crimping, and it is difficult to adjust the pressure, the adhesive strength tends to vary, and defective products are likely to occur. Japanese Patent Publication No. 63-67808 discloses a joined body of modified PTFE molded articles, but the joining is performed by heat-compression bonding, that is, by heating while applying pressure from the outside, and joining the molded articles. . This method is suitable for joining thin molded products such as sheets and films, but when joining thick molded products, the bonding strength varies as in the method described in the above-mentioned Hoechst catalog. Are likely to occur and defective products are likely to occur.

In Japanese Patent Application Laid-Open No. 55-57429, a special mold having a central mold inserted through a cylindrical mold is used. In addition, a method is disclosed in which the joint is heated to a temperature equal to or higher than the melting point and the butted portions at both ends are melt-joined by the expansion pressure. However, there are difficulties with homogeneous joining.

When manufacturing a thick-walled container having a bottom portion and a side wall, there is known a method in which a mold is filled with a modified PTFE resin and a molder and then pressurized. Since the compression distance is short at the bottom and the compression distance is long at the side wall, cracks are likely to occur near the boundary between the side wall and the bottom, and it is difficult to obtain a good molded product. Further, in any of the above methods, steps or protrusions remain on the outer surface of the molded product at the joint, and dust accumulates particularly on the steps or irregularities on the inner surface, which is a problem when used as a container for high-purity liquid. was there.

As a method of manufacturing a container of PTFE or modified PTFE, a method of welding a molded part for forming a container such as two or more sheets using a molten fluororesin is known. As the welding rod is made of the molten fluorine, the surface of the weld surface becomes uneven, making it unsuitable for a high-purity liquid container.

As a method for manufacturing a container of high-purity liquid, a mouth-to-mold method of molten fluororesin is also known, but the inner surface is formed by growing a layer on top of the molten resin powder as it is deposited. Because of this, the container has considerable irregularities, and a container manufactured by this method is not desirable as a container for a high-purity liquid.

By the way, Japanese Patent Application Laid-Open Publication No. Hei 4-357015 (Japanese Patent Publication No. Hei 6-102432) discloses that a thermoplastic resin sheet composed of one or more sections is placed along the inner surface of a mold. A method is disclosed in which a sheet is arranged and heated to a temperature equal to or higher than the melting point of the resin while the mold is rotated, so that the sheet is heat-sealed and integrated. However, even if a non-thermoplastic modified PTFE sheet is molded by rotating the same mold, a modified PTFE molded product that is homogeneous and strong integrated at the joint surface and has a smooth inner surface without steps and unevenness is obtained. It is unpredictable whether it will be obtained.

Further, even if the sheet is heat-sealed and integrated with a thermoplastic resin sheet, there is no disclosure of a method of forming a cylindrical protrusion such as a branch pipe or a side pipe. When the protruding part is manufactured by joining it to the container or pipe as the main body, welding is similar to spot welding at the edge, narrow gap, curved surface, etc. of the molded product, and distortion of the part or excessive heating Insufficient welding is likely to occur due to shortage.

Disclosure of the invention

An object of the present invention is to solve the above-mentioned drawbacks of the prior art, to form a molded part homogeneously and strongly at the joint surface, and to eliminate the steps and irregularities on the inner and outer surfaces, particularly the inner surface of the molded product. Moreover, it is an object of the present invention to provide a method for producing a tetrafluoroethylene-based polymer-joined molded article in which a cylindrical protrusion is firmly joined to a molded article body.

To achieve the above object, according to the present invention, there are provided surfaces having surfaces to be joined to each other. One or more tetrafluoroethylene-based polymer molded parts are disposed along or near the inner wall surface of the molding die, and one or more A tetrafluoroethylene-based polymer cylindrical molded part is disposed in a through hole provided in the molding die, and the molding die in which the molded part and the cylindrical molded part are disposed is rotated about at least one axis. While heating, the molded part and the cylindrical molded part are heated to a temperature equal to or higher than the melting point of the tetrafluoroethylene-based polymer, and the molded part and the cylindrical molded part are joined and integrated at their joint surfaces. Further, there is provided a method for producing a tetrafluoroethylene-based polymer bonded molded article, characterized in that the outer surface of the molded part is finished in a shape following the inner wall surface of the molding die.

In addition, when using a reinforcing material and, if necessary, a melt-moldable fluororesin, and laminating the former or both at the same time as the joining and molding of the molded part, at least one part of the molded part and the inner wall surface of the molding die are required. If necessary, a reinforcing material may be interposed with a melt-moldable fluororesin, and may be joined and molded in the same manner as described above.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view of a mold used in Example 1 and a molded part and a cylindrical molded part arranged therein.

FIG. 2 is a cross-sectional view of a mold used in Example 2 and a molded part and a cylindrical molded part arranged therein.

BEST MODE FOR CARRYING OUT THE INVENTION

The shape of the molded part may be a sheet, a cylinder, a cylinder, a block, a rod, or other various shapes, and is preferably a sheet (with a thickness of l to 5 mm).

The molding die is not particularly limited as long as it is generally used for molding a fluororesin. Preferably, a molding die such as a cylinder or a bottle which is usually used in a mouth mold is used. A through hole is provided in at least one place of the molding die, and a cylindrical molded part constituting a cylindrical projecting portion is arranged in that portion.

The production method of the present invention is particularly useful as a method for producing a molded article such as a container with a stopper for storing and / or transporting a liquid, a tubular article having a branch pipe, and a tank having a side pipe. The tetrafluoroethylene-based polymer of the present invention means modified polytetrafluoroethylene (hereinafter, modified PTFE) or a copolymer of tetrafluoroethylene and another monomer.

Modified PTFE is a polymer obtained by polymerizing tetrochloroethylene in the presence of a modifying monomer.

The monomers for modification of PTFE, X (CF ₂₎ (wherein, X is hydrogen, fluorine or chlorine, n represents an integer of 1~6) _n OCF = CF ₂ or 〇 _{3 7} (0_Rei? ₂ CF ₂ CF ₂ ) _m (OCF (CF ₃ ) CF ₂ ) ₁ OCF = CF ₂ (where m and 1 represent integers from 0 to 4. However, these cannot be 0 at the same time. ), CF ₃ — CF = CF ₂ , CF ₂ = CFH, CF ₂

_{= CFC 1, CF 2 = CH} 2, RfCY = CH 2 ( wherein, Rf is a linear or molecular of polyfurfuryl O b alkyl group having a carbon number of 3 to 21, Y is a hydrogen atom or a fluorine atom. ), And fluorine-containing unsaturated monomers other than TFE. Monomers for normal degeneration 0.01 against TF E: used in an amount of 1.0 weight ^_0/0.

The specific melt viscosity of the modified PTFE used in the method of the present invention is usually 1 × 10 ⁷ to 1 × 1.

It is 0 ¹¹ voices, preferably 1 × 10 ⁸ to 1 × 10 ¹⁰ voices.

Examples of copolymers of tetrafluoroethylene and other monomers include tetrafluoroethylene / hexafluoropropylpyrene copolymer, tetrafluoroethylene Z-perfluoro (alkyl vinyl ether) copolymer, and ethylene _/ tetrafluoroethylene. Loethylene copolymers, vinylidene fluoride Z tetrafluoroethylene copolymers and the like are exemplified. In particular, a tetrafluoroethylene Z hexafluoropropylpyrene copolymer and a tetrafluoroethylene perfluoro (alkylbutylene) copolymer (hereinafter, referred to as PFA) are preferable.

Examples of the reinforcing material include glass cloth, glass knit, carbon cloth, carbon net, and the like.

Examples of the melt-moldable fluororesin include polyvinylidene fluoride, polychloro-trifluoro ethylene, and the like in addition to the above-mentioned copolymer of tetrafluoroethylene and other monomers.

For molded parts of modified PTFE, use modified PTFE molding pad It is pre-compressed according to the method and conditions, and if necessary, calcined.

The molded part is usually a fired molded article, but an unfired one such as a preformed article may be used.

The cylindrical molded part that constitutes the cylindrical protrusion is a force produced by machining from a block molded product of a tetrafluoroethylene polymer or a hollow cylindrical molded product, and a film or sheet of a tetrafluoroethylene polymer. The two ends can be welded or welded together to form a cylinder, which can be flared. Alternatively, it can be produced from a molding powder of a tetrafluoroethylene polymer by rubber molding or hydraulic molding.

One or more of such molded parts are placed in a molding die having an inner wall surface corresponding to the outer surface of the final molded product, and heated to a temperature equal to or higher than the melting point of the tetrafluoroethylene-based polymer. To rotate. The rotation is performed about one or more axes of the mold, preferably about two axes. The rotational peripheral speed is 0.5 m / min or more around a specific axis, preferably 10 to 2 OmZ. The upper limit of the rotational peripheral speed is not particularly limited, but is usually 50 m.

In the joining molding method of the present invention, the heating rotation time is not particularly limited. It is sufficient that the part and the cylindrical molded part are sufficiently heated so that they are uniformly and strongly integrated at the joint surface.

ADVANTAGE OF THE INVENTION According to the manufacturing method of this invention, the homogenous force is strongly integrated at the joining surface, it has a smooth inner surface without a level | step difference and unevenness, Furthermore, the cylindrical protrusion is firmly joined to the molded article main body. It is possible to obtain a polyethylene-based polymer bonded molded article.

Example

Hereinafter, the present invention will be described specifically with reference to Examples.

Example 1

A sheet with a thickness of 2400 / xm extruded using PFA (trade name: NEOFLON AP-230) pellets. From this sheet, two disks with the same diameter as in the mold ^ 1 and 3 were created. The disk 3 was provided with a hole corresponding to the opening of the cylindrical body 5 (see FIG. 1).

The inner diameter of the mold was about 200 mm. From the same sheet, a sheet 2 having a length equal to the inner circumference of the mold 4 and an appropriate width corresponding to the height of the container was created (see Fig. 1).

On the other hand, a cylindrical body 5 having a cross section as shown in FIG. 1 was obtained by compression molding of modified PTFE using a mold.

As shown in FIG. 1, sheet 2 (width 230 mm) was rolled up and placed so as to be in contact with the entire inner wall of the mold, and sheets 1 and 3 were placed at the upper and lower ends, respectively. The cylindrical body 5 was arranged in a through-hole in a mold.

Thereafter, the mold was placed in a heating furnace and heated at 340 ° C. for about 2.0 hours at a rotation speed of 20 rpm and a revolution speed of 10 rpm while rotating the mold biaxially. The mold is moved to a room temperature of 25 ° C while rotating biaxially, and cooled at room temperature for about 30 minutes.After removing the molded product from the mold, it has a protrusion at the upper end. A seamless bottle with a uniform thickness was obtained along the inner surface of the mold.

Example 2

As shown in Fig. 2, a sheet 6 with a thickness of 2400 // m, extruded from PFA (neoflon AP-230) pellets, was rolled and placed in a cylindrical mold 4,. Similarly, a tubular body 7 serving as a branch pipe was obtained from the PFA, and placed in the through hole of the mold.

The mold was heated in a heating furnace at 340 ° C. for about 1.5 hours while rotating biaxially at a rotation speed of 20 rpm and a revolution speed of 10 rpm. After moving to a room temperature of 25 ° C and cooling at room temperature for about 30 minutes while rotating, the molded product was taken out of the mold and a tube with a branch tube on the tube side was obtained.

Claims

The scope of the claims

1. One or more tetrafluoroethylene polymer molded parts having surfaces to be joined to each other are placed along or near the inner wall surface of the molding die, and the force is applied to the molded parts. One or more tetrafluoroethylene-based polymer cylindrical molded parts having a part to be joined with the molded part are disposed in a through-hole provided in the molding die, and the molded part and the cylindrical molded part are disposed. Heating the molded part and the cylindrical molded part to a temperature equal to or higher than the melting point of the tetrafluoroethylene polymer while rotating the arranged molding die about at least one axis; And joining them together at their joint surfaces, and finishing the outer surface of the molded part to a shape that follows the inner wall surface of the molding die. .

2. The method according to claim 1, wherein the molded part is made of modified polytetrafluoroethylene.

.

3. The production method according to claim 1, wherein the molded part is obtained by pre-compression molding of a modified polytetrafluoroethylene molding powder.

4. The production method according to claim 1, wherein the molded component is obtained by pre-compression molding of modified polytetrafluoroethylene molding powder and then firing.

5. Modified polytetrafluoroethylene full O b The process according to any one of claims 2-4 which ethylene has a ^{1 X 1 0 7 ~1 X 1} 0 1 1 ratio melting viscosity of Boyes.

6. Modified polytetramethylene full O b The process according to any one of claims 2-4 which ethylene has a ^{1 X 1 0 8 ~1 X 1} 0 1 0 ratio melting viscosity of Boyes.

7. The production method according to claim 1, wherein the molded part comprises a tetrafluoroethylene-perfluoroalkylbutyl ether copolymer.

8. The method according to claim 7, wherein the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer has a specific melt viscosity of 1 × 10 ⁴ to 1 × 10 ⁶ voids.

9. The method according to claim 1, wherein the molded part comprises a tetrafluoroethylene-hexafluoropropylpyrene copolymer.

10. Tetrafluoroethylene-hexafluoropropylene copolymer is 1 X The method according to claim 9 having a ^{1 0 4 ~ 1 X 1 0} 6 specific melt viscosity of Boyes.

11. The production method according to any one of claims 1 to 10, wherein the molded article is a hollow container having a cylindrical cap mounting portion.

12. The method according to any one of claims 1 to 10, wherein the molded article is a pipe having a branch pipe.

13. The production method according to any one of claims 1 to 10, wherein the molded article is a tank having a side tube.

14. The method according to any one of claims 1 to 13, wherein the molding die is rotated at a peripheral speed of at least 0.5 m / min about one axis.

15. The method according to any one of claims 1 to 13, wherein the molding die is rotated about two axes.

16. If a reinforcing material is required between at least one part of the molded part and the inner wall surface of the molding die, it is interposed with a melt-moldable fluororesin, and the lamination of the reinforcing material and the melt-moldable fluororesin simultaneously. The method according to any one of claims 1 to 15, which is performed.