CN112549485A

CN112549485A - Polytetrafluoroethylene multi-cavity extrusion pipe and processing method thereof

Info

Publication number: CN112549485A
Application number: CN202011296632.9A
Authority: CN
Inventors: 谭宏伟; 陈越; 韩桂芳; 刘长海; 付师庆
Original assignee: Shandong Dongyue Polymer Material Co Ltd
Current assignee: Shandong Dongyue Polymer Material Co Ltd
Priority date: 2020-11-18
Filing date: 2020-11-18
Publication date: 2021-03-26
Anticipated expiration: 2040-11-18
Also published as: CN112549485B

Abstract

The invention belongs to the technical field of polytetrafluoroethylene pipe processing and manufacturing, and particularly relates to a polytetrafluoroethylene multi-cavity extrusion pipe and a processing method thereof. The PTFE multi-cavity extrusion pipe comprises 2 or more than 2 cavities, and the cavities are independent. The PTFE multi-lumen extruded tube is formed by a multifiber die. The PTFE multi-cavity extrusion pipe improves the dimensional stability and the repeatability of the PTFE multi-cavity extrusion pipe through a fixing device. The invention has reasonable design, changes the PTFE extrusion pipe with a single cavity channel into a PTFE extrusion pipe with multiple cavity channels, and needs the PTFE extrusion pipe to be molded at one time, thereby avoiding multiple processing and greatly improving the practicability and the applicability.

Description

Polytetrafluoroethylene multi-cavity extrusion pipe and processing method thereof

Technical Field

The invention belongs to the technical field of polytetrafluoroethylene pipe processing and manufacturing, and particularly relates to a polytetrafluoroethylene multi-cavity extrusion pipe and a processing method thereof.

Background

Polytetrafluoroethylene (PTFE), commonly known as "Plastic king", is a high molecular material with special properties and occupies an extremely important position in new materials. PTFE has excellent performances of excellent chemical reagent corrosion resistance, extremely low surface friction coefficient, high temperature resistance, good dielectric property, electric insulation property and the like, and is widely applied to the fields of aerospace, electronics, metallurgy, medicine, semiconductors and the like.

The PTFE extruded pipe can be widely applied to conveying corrosive liquid or gas, such as hydraulic fluid and fuel oil in the aerospace industry; high-pressure air, fuel and hydraulic transmission in the automobile industry; the delivery of high purity fluids in the pharmaceutical industry, and the like. The extrusion pipe used in the existing fluid conveying or heat dissipation field is single-cavity, cannot meet the requirement of fluid conveying, and the using amount of the pipe body needs to be reduced as much as possible in many places so as to achieve the purposes of reducing the volume, optimizing the structure, facilitating installation and the like. However, in practical applications, the transportation or fixing by using a plurality of pipelines not only increases the cost, but also occupies a large space, so that the practicability and the applicability are limited.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the PTFE extrusion pipe with the single cavity channel is changed into the PTFE extrusion pipe with the multiple cavity channels, the structural design is reasonable, one-step forming can be achieved, multiple times of processing are avoided, and the practicability and the applicability of the PTFE extrusion pipe are greatly improved.

The polytetrafluoroethylene multi-cavity extrusion pipe comprises 2 or more than 2 cavities, the cavities are independent from one another, the wall thickness between the cavities is 1.0-3.0mm, and the shapes of the cavities are preferably circular or elliptical.

Preferably, the diameter of each channel is 20-70% of the total diameter of the channel. The channels can be the same or different; or may be partially the same or partially different.

The invention relates to a processing method of a polytetrafluoroethylene multi-cavity extruded pipe, which comprises the following steps:

1) mixing materials: adding the auxiliary oil into the sieved polytetrafluoroethylene dispersion resin, uniformly mixing, and curing at 25-40 ℃ for 24-48 h;

2) preforming: adding the cured polytetrafluoroethylene dispersion resin obtained in the step 1) into a cylinder of an extruder, applying pressure of 2-5MPa at a pressing speed of less than 50mm/min, and maintaining the pressure for 20-40min to obtain a preformed blank;

3) paste extrusion: installing a mouth mold and a needle mold containing 2 or more than 2 core rods on an extruder, then placing the preformed blank obtained in the step 2) in a cylinder barrel, closing a mold, installing a corresponding fixing device between the core rods and the mouth mold according to the shape of the core rods before pasty extrusion, then carrying out pasty extrusion, pushing out the fixing device along with the increase of extrusion pressure, simultaneously extruding a multi-cavity extrusion pipe from the mouth mold, removing auxiliary oil after extrusion, sintering and cooling to finally obtain the polytetrafluoroethylene multi-cavity extrusion pipe.

Preferably, the auxiliary oil in the step 1) is isoparaffin solvent oil or perfluorinated liquid of 2-trifluoromethyl-3-ethoxy dodecafluorocarbon hexane, and the addition amount is 15-25 wt% of the sieved polytetrafluoroethylene dispersion resin.

Preferably, the pin die containing 2 or more than 2 core rods in the step 3) consists of a pin die top and the core rods, and the pin die top and the core rods are sequentially a thread area, a cylindrical area, a conical area and the core rods from top to bottom.

The threaded zone of the pin die is mainly used for connecting the extruder, thus needs to go deep into the extruder, and can also increase the strength of the pin die, but because it goes deep into the extruder, it is not compared with other parts; the cylindrical area of the needle die needs to have a certain length, preferably 10-13% of the total length of the needle die, the conical area of the needle die is mainly used for enabling the extruded polytetrafluoroethylene to flow towards a certain direction, preferably the axial direction of the core rod, so that the extruded polytetrafluoroethylene cannot be too large or too small easily, the angle of the conical part is preferably 40-80 degrees, and the two areas are the areas necessary for maintaining the shape of the pipe; the core rod of the needle die is a long straight pipeline with air vents, the air vents are mainly used for discharging auxiliary oil volatilized in the drying process, the length of the core rod is preferably 80-89% of the total length of the needle die, gaps among the core rods are preferably 1-3mm, and the size of the air vents of the core rod is preferably 0.5-2 mm.

Preferably, the material of the needle mold is one of 304 stainless steel, polyimide, nylon or polyformaldehyde.

The PTFE multi-cavity extrusion pipe is mainly formed by continuously filling a gap part of a needle die with polytetrafluoroethylene through extrusion to form a hollow pipeline, however, in the process, the continuous increase of pressure can cause the movement of a core rod to the axial center direction, so that the wall thickness of the extrusion pipe is different, the wall thickness is uneven, the pressure is too large, and even the independence among the multi-cavity channels is damaged, so that the occurrence of the through cavity channels is caused, and under the condition, the repeatability of the PTFE multi-cavity extrusion pipe is very poor.

The fixing device can effectively solve the problem, and the uniformity of wall thickness and the formation of multiple cavities can be effectively ensured. The shape of the fixing device is consistent with the shape of the gap area between the core rods and the inner wall of the neck ring mold, but a certain gap is required to be formed between the core rods and the inner wall of the neck ring mold, so that excessive friction is prevented; the fixing device needs to have certain hardness to ensure that the fixing device does not deform under the action of external force, so that the wall thickness of the extruded tube is not changed; the fixture preferably has a smooth, soft surface to ensure that the mandrel is not damaged.

Preferably, the length of the fixing device in the step 3) is 50-90% of the length of the equal diameter outlet of the die, and the gap between the fixing device and the needle die containing 2 or more than 2 core rods is 0.2-0.5 mm.

Preferably, the fixing device is made of one of polypropylene, polyethylene, polyvinyl chloride, polystyrene, polyformaldehyde, polyamide, polycarbonate, polyphenylene oxide, polysulfone, polytetrafluoroethylene, polyphenylene sulfide or polymethyl methacrylate.

Further, the PTFE in the present invention may contain a filler. The preferable filler is one or more of organic filler and inorganic filler, the organic filler is one or more of polyphenyl ester, polyphenylene sulfide, polyimide, polyamide or wholly aromatic polyester resin, and the inorganic filler is one or more of metal powder, graphite, graphene, carbon black, carbon nanotubes, carbon fibers, glass fibers, ceramic powder, talcum powder, zinc oxide, tin oxide, calcium oxide, titanium oxide, aluminum oxide, magnesium oxide, silicon dioxide, calcium carbonate, potassium titanate, silicon carbide, calcium fluoride, boron nitride, barium sulfate, molybdenum disulfide or potassium carbonate whisker. Meanwhile, different types of fillers may be used in combination, or the same type of fillers having different particle sizes or shapes may be used in combination.

The experimental procedures not described in detail in the present invention were carried out according to the routine procedures in the art.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention has reasonable structure arrangement, changes the PTFE extrusion pipe with a single cavity channel into a PTFE extrusion pipe with multiple cavity channels, and needs one-step molding of the PTFE extrusion pipe, thereby avoiding multiple processing; and when in use, the device is beneficial to realizing the management of the pipeline and reducing the volume of the device on the whole. Meanwhile, different cavities are independent, so that multiple cavities among pipelines are realized, and the applicability and the practicability of the pipeline are greatly improved.

2. The addition of the fixing device stabilizes the wall thickness between the cavities, greatly improves the stability and the repeatability of the PTFE multi-cavity extrusion tube, and has good practical effect.

Drawings

FIG. 1 a is an axial cross-sectional view of the needle die of the present invention; b is a radial sectional view of the PTFE multi-cavity extruded tube, c is an axial sectional view of the top of the needle die, and d is an axial sectional view of a single core rod.

FIG. 2 is an axial cross-sectional view of the needle die for processing PTFE two-chamber extruded tubes of the present invention.

Fig. 3 is a schematic radial cross-sectional view of a PTFE two-lumen extruded tube in example 1 of the present invention.

FIG. 4 is a schematic axial sectional view of a PTFE multi-lumen extruded tube processing die in example 2 of the present invention.

FIG. 5 is a schematic radial cross-sectional view of a PTFE multi-lumen extruded tube of example 2 of the present invention.

FIG. 6 is a schematic radial cross-sectional view of a different arrangement of a PTFE multi-lumen extruded tube of the present invention.

In the figure, 1, the threaded area; 2. a cylindrical region; 3. a conical region; 4. and (4) a core rod.

Detailed Description

The present invention will be further described with reference to the following examples.

Example 1

A method for processing a PTFE two-cavity extruded pipe with the same inner cavity diameter. The method comprises the following specific steps:

(1) mixing materials: sieving PTFE dispersion resin DF-2041 (Dongyue group) stored at the temperature of below 20 ℃, adding Mobil Isopar-G auxiliary oil accounting for 20 wt% of the PTFE dispersion resin after sieving, manually rolling for 5min, and curing the uniformly mixed PTFE extrusion material at the ambient temperature of 24 +/-1 ℃ for 24 h;

(2) preforming: pouring the cured PTFE extruded material in the step (1) into a cylinder barrel of an extruder for preforming, and pressing for 30min at a pressing speed of 50mm/min and a pressing pressure of 2MPa to obtain a preformed green body;

(3) paste extrusion: installing the double-core needle die shown in fig. 2 and a mouth die with the outlet caliber of 5mm on an extruder, then placing the preformed blank obtained in the step (2) in a cylinder barrel, closing the die, installing a corresponding fixing device before paste extrusion, then extruding at the extrusion speed of 4mm/min, removing auxiliary oil after extrusion, sintering and cooling to finally obtain a two-cavity PTFE extruded tube with the outer cavity diameter of 5mm, the inner cavity diameter of 1mm and the wall thickness of 1mm, wherein the surface of the obtained PTFE two-cavity extruded tube is smooth and transparent, and fig. 3 is a schematic radial cross-sectional view of the obtained PTFE two-cavity extruded tube.

Example 2

A method for processing PTFE multi-cavity extruded tubes with different inner cavity diameters. The method comprises the following specific steps:

a PTFE multi-lumen extruded tube was obtained under the same conditions as in example 1 except that a multi-needle die as shown in FIG. 4 and a die having an outlet diameter of 10.5mm were used and a PTFE dispersion resin DF-204S (Toyue corporation) was used as an extrudate. A white and smooth multi-cavity PTFE extruded tube with an outer cavity diameter of 10.5mm, a middle inner cavity diameter of 4.5mm, small cavities on both sides having a diameter of 1mm, and a wall thickness of 1mm was obtained, and fig. 5 is a schematic radial sectional view of the obtained PTFE multi-cavity extruded tube.

While the above description is made of an example of a PTFE multi-lumen extruded tube of the present invention, including the one shown in FIG. 6, it should be understood that the scope of the present invention is not limited by FIG. 6, but rather, it is intended to cover all modifications, equivalents, and improvements falling within the spirit and scope of the present invention.

Claims

1. A polytetrafluoroethylene multicavity extrusion pipe which characterized in that: the polytetrafluoroethylene multi-cavity extrusion pipe comprises 2 or more than 2 cavities, the cavities are independent from one another, and the wall thickness between the cavities is 1.0-3.0 mm.

2. A polytetrafluoroethylene multi-lumen extruded tube according to claim 1 wherein: the shape of the cavity is circular or oval.

3. A polytetrafluoroethylene multi-lumen extruded tube according to claim 1 or claim 2, wherein: the diameter of each cavity is 20-70% of the total diameter of the cavity.

4. A method of manufacturing a polytetrafluoroethylene multi-lumen extruded tube according to claim 1, wherein: the method comprises the following steps:

1) mixing materials: adding the additive oil into the sieved polytetrafluoroethylene dispersion resin, uniformly mixing and curing;

2) preforming: adding the cured polytetrafluoroethylene dispersion resin obtained in the step 1) into a cylinder of an extruder, and performing to obtain a preformed blank;

3) paste extrusion: installing a mouth die and a needle die containing 2 or more than 2 core rods on an extruder, then placing the preformed blank obtained in the step 2) in a cylinder barrel, closing a die, installing a fixing device between the core rods and the mouth die in a matching manner before pasty extrusion, then carrying out pasty extrusion, removing auxiliary oil after extrusion, sintering and cooling to obtain the polytetrafluoroethylene multi-cavity extruded tube.

5. A method of manufacturing a multi-lumen polytetrafluoroethylene extruded tube according to claim 4, wherein: in the step 1), the auxiliary oil is isoparaffin solvent oil or perfluorinated liquid of 2-trifluoromethyl-3-ethoxy dodecafluorocarbon hexane, and the addition amount of the auxiliary oil is 15-25 wt% of the sieved polytetrafluoroethylene dispersion resin.

6. A method of manufacturing a multi-lumen polytetrafluoroethylene extruded tube according to claim 4, wherein: the curing in the step 1) is performed for 24-48h at the temperature of 25-40 ℃.

7. A method of manufacturing a multi-lumen polytetrafluoroethylene extruded tube according to claim 4, wherein: and 2) preforming at a pressing speed of less than 50mm/min, applying a pressure of 2-5MPa, and maintaining the pressure for 20-40min to obtain a preformed blank.

8. A method of manufacturing a multi-lumen polytetrafluoroethylene extruded tube according to claim 4, wherein: the needle die containing 2 or more than 2 core rods in the step 3) sequentially comprises a thread area (1), a cylindrical area (2), a conical area (3) and the core rods (4) from top to bottom, wherein the length of the cylindrical area (2) is 10-13% of the total length of the needle die, and the angle of the conical area (3) is 40-80 degrees.

9. A method of manufacturing a multi-lumen polytetrafluoroethylene extruded tube according to claim 8, wherein: the length of the core rod (4) is 80-89% of the total length of the needle die, the gap between the core rods (4) is 1-3mm, the core rod (4) is a long straight pipeline with an exhaust hole, and the diameter of the exhaust hole is 0.5-2 mm.

10. A method of manufacturing a multi-lumen polytetrafluoroethylene extruded tube according to claim 4, wherein: the length of the fixing device in the step 3) is 50-90% of the length of the equal-diameter outlet of the neck ring mold, the shape of the fixing device is consistent with the shape of the core rod and the shape of a gap area between the core rod and the inner wall of the neck ring mold, and the gap between the fixing device and the needle mold containing 2 or more than 2 core rods is 0.2-0.5 mm.