JPH0315077B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a fluororesin tube bundle in which a plurality of fluororesin tubes are bundled and integrated with a sleeve, and in particular, the present invention relates to a fluororesin tube bundle in which a plurality of fluororesin tubes are bundled and integrated with a sleeve. This relates to a fluororesin tube bundle with less crushed or deformed end openings.

[Conventional technology]

Among many polymer materials, fluororesin exhibits particularly excellent properties in terms of chemical resistance, heat resistance, non-staining property, etc., and is therefore widely used in various fields. Tubes made of fluororesin are often used as a single piece as piping materials like tubes made of other materials, but tube bundles made by bundling many tubes and integrating both ends, such as As shown in Japanese Patent Application Laid-open No. 60-259898, it is used as a heat exchanger tube for heat exchangers due to its chemical resistance and heat resistance, or it is used as a heat transfer tube for heat exchangers due to its chemical resistance and non-contamination property. The use as a degassing pipe in an air system is also being considered (Utility Model Application No. 62-27703, proposed by the present applicant).

By the way, in order to facilitate the terminal connection of these fluororesin tube bundles, a fluororesin sleeve is fitted around the end, and each tube and sleeve are integrally bonded to form a honeycomb-like airtight joint at the end. Therefore, variations in the opening area of each tube after molding have a large effect on the performance when actually used in the above device. That is,
These variations appear as differences in flow velocity when fluid flows into the tubes, causing a decrease in heat exchange efficiency or deaeration efficiency, and variations, so especially when using tube bundles for such applications, Needless to say, it is desired that the tube bundles have no collapse of each tube at the end, and that deformation such as flattening is as small as possible.

[Problem that the invention seeks to solve]

However, conventionally, the ends of these tube bundles have been formed by heat fusion because the fluororesin is non-adhesive, and as a result, the tubes soften or expand during heating, causing the tubes to collapse. They often bend or deform, require advanced manufacturing techniques, and are not very easy to work with.

In addition, when using a tube made of fluorinated ethylene resin (hereinafter referred to as PTFE), which has particularly excellent mechanical strength, heat resistance, chemical resistance, and non-staining properties among fluorocarbon resins, PTFE has a non-adhesive property. In addition, it has a significantly higher melt viscosity than other fluororesins and exhibits almost no fluidity even above its melting point, making it difficult to thermally fuse. For this reason, there is a drawback that poor airtightness is likely to occur at the joint portion when the terminal is formed.

Furthermore, since PTFE is difficult to heat-seal, in order to increase the strength of the joint, a sleeve with a smaller inner diameter is used to fit over the end of the PTFE tube bundle, and each PTFE tube is kept in close contact with the other and heat-sealed. When fusion is performed, each PTFE tube expands significantly when it exceeds its melting point, and the sleeve also expands inward, so the expansion pressure causes each PTFE tube to expand significantly.
Although the tube can be crimped to improve the bond strength,
On the other hand, the tubes located at the outermost periphery of the tube bundle are particularly prone to collapse, resulting in problems such as a portion of the terminal opening being blocked or the opening being collapsed and the flow path being narrowed.

Therefore, as a method for manufacturing a PTFE tube bundle, Japanese Patent Application Laid-Open No. 60-259898 discloses that the inside of a PTFE tube is filled with a powdered or granular heat-resistant material such as glass beads or metal powder to prevent crushing.
Furthermore, a method has been proposed in which a heat-melting fluororesin is provided on the outer periphery of the end of a PTFE tube and the two are bonded together via the heat-melting fluororesin. However,
In this method, it is not only difficult to fill each tube with filler and workability is poor, but also, when the PTFE tube is melted by heating, the filler may adhere to the inner circumferential surface of the tube and remain. .
Such tube bundles have the problem that they cannot be used in applications such as degassing tubes in which highly pure liquids are passed through the tubes because they cause contamination.

In view of these problems of the prior art, this invention
The purpose of the present invention is to provide a fluororesin tube bundle in which the deformation of the opening of each tube is extremely small, the opening state is well maintained, and is easy to manufacture.

[Means for Solving the Problems] In order to solve the above-mentioned problems of the prior art, according to the present invention, a plurality of fluorine resin tubes that are bundled, and an end portion of the plurality of fluororesin tubes are Joints formed by heat-shrinkable tubes made of heat-melting fluororesin that are individually fitted onto the outside, shrink by heating, and then melted and solidified to join and integrate each fluororesin tube, and these fluororesin tubes. A fluororesin sleeve is fitted over the end of the bundle, and a fluororesin sleeve is provided between the fluororesin sleeve and the bundle of fluororesin tubes, and is melted by heating and further solidified to join and integrate the two. A fluororesin tube bundle is constructed that includes a tubular joint formed by heat-melting fluororesin tubes.

In this configuration, the fluororesin tubes are preferably made of PTFE from the viewpoint of various properties, and in this case, the heat-shrinkable tubes that form the joints of each fluororesin tube, For the tube that forms the joint between the bundle and the fluororesin sleeve, a tube made of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (hereinafter referred to as PFA) is suitable from the viewpoint of joint strength.

[Effect]

The fluororesin tube bundle according to the present invention exhibits fluidity when heated above its melting point and is easy to bond with PTFE or other fluororesins.
A tube made of a heat-melting fluororesin such as PFA is provided between the fluororesin sleeve and the bundle of fluororesin tubes, and a heat-shrinkable tube made of the same resin is placed externally at the end of each fluororesin tube. When these are fitted and heated above the melting point of the heat-melting fluororesin, the heat-shrinkable tubes melt and flow, reliably filling the gap between adjacent fluororesin tubes and solidifying. As a result, adjacent fluororesin tubes are bonded together with this melted heat-shrinkable tube serving as a joint. Furthermore, the tubes interposed between the bundle of these fluororesin tubes and the fluororesin sleeve are also melted, and the gap between the outer fluororesin tube and the fluororesin sleeve is closed and solidified to form a tubular shape. These joints form an airtight integral structure at the end.

In this case, the heat-shrinkable tube fitted onto each fluororesin tube shrinks when heated, tightens the fluororesin tube from the outside, suppresses expansion of the fluororesin tube due to heating, and softens the fluororesin tube. Melts while preventing deformation due to pressure between tubes. Therefore, even after the heat-shrinkable tubes are melted, the fluororesin tubes have a smaller expansion coefficient than in the conventional method of heat-sealing the tubes without restraining them, and they hardly press against each other.

In addition, the tube, which is provided between the fluororesin sleeve and the bundle of fluororesin tubes and is melted by heating, absorbs the slight expansion pressure remaining in each fluororesin tube, especially the outer fluororesin tube. To fill a gap between a fluororesin tube and a fluororesin sleeve, to easily absorb the expansion pressure to the inside of the fluororesin sleeve, and to solidify while preventing pressure on the inner fluororesin tube.

Therefore, each fluororesin tube does not press against each other during terminal molding, and the fluororesin sleeve does not press against the inner fluororesin tube, so each fluororesin tube has a It is reliably joined and integrated with the sleeve without causing crushing or deformation.

〔Example〕

FIG. 1 is a perspective view with one end cut away showing an embodiment of a fluororesin tube bundle according to the present invention, and FIG. 2 is a longitudinal sectional side view of the end.

This fluororesin tube bundle 1 includes a plurality of bundled fluororesin tubes 2 and a joint 3 that joins and integrates the ends of these fluororesin tubes 2.
A fluororesin sleeve 4 is fitted over the end of the bundle of fluororesin tubes 2, and the fluororesin sleeve 4 and the bundle of fluororesin tubes 2 are joined and integrated, and the joint portion 3 is In addition, it is composed of a tubular joint part 5 that forms an airtight integral structure at the end while holding the opening of each fluororesin tube 2.

Here, the joint part 3 and the tubular joint part 5 are made of a heat-melting fluororesin such as PFA that exhibits fluidity when heated above its melting point, and as shown in detail in FIG. It fills the gap between the resin tubes 2 and the gap between the fluororesin tube 2 and the fluororesin sleeve 4 to bind and integrate them, and an example of the method for forming it is as follows.
As shown in Figure 3, first, the fluororesin tube 2
A heat-shrinkable tube 3a made of a heat-melting fluororesin is fitted onto the end of the tube, a plurality of these tubes are bundled, and a tube 5a made of a heat-flowable fluororesin and a fluororesin sleeve 4 are sequentially attached to the end of the tube 5a. fit. When this end portion is heated using a heater or the like, the heat-shrinkable tube 3a contracts and tightens each fluororesin tube 2 from the outside. By tightening this heat shrink tube 3a, each fluororesin tube 2
Since the expansion in the radial direction is suppressed and compression of adjacent tubes is prevented, each fluororesin tube 2 will not collapse or change even in a softened state. When heated further, the heat-shrinkable tube 3a melts while suppressing the expansion of the fluororesin tube 2, and the tube 5a interposed between the bundle of these fluororesin tubes 2 and the fluororesin sleeve 4 also melts. . Since this melted heat-shrinkable tube 3a has fluidity, it is pressed by the slight expansion pressure of each fluororesin tube 2 outward in the radial direction, and the excess heat-meltable fluororesin is removed.
It escapes in the longitudinal direction and fills the gap between the fluororesin tubes 2 while absorbing their expansion pressure. Also,
Since the molten tubes 5a are similarly fluid, the radially outward expansion pressure of the fluororesin tubes 2 located particularly on the outer side of the bundle of fluororesin tubes 2 and the diameter of the fluororesin sleeve 4 are Pressed by the expansion pressure inward, the excess resin escapes in the longitudinal direction and fills the gap between the bundle of fluororesin tubes 2 and the fluororesin sleeve 4 while absorbing the expansion pressure. Then, when the ends are cooled, the heat-melting fluororesin that filled the gap solidifies and binds them together, forming a joint 3 and a tubular joint 5, respectively, forming an airtight integral structure (see Fig. 1). , second
figure).

In the above embodiment, a plurality of fluororesin tubes 2 each having a heat-shrinkable tube 3a fitted on the end thereof are bundled together, a heat-melting fluororesin tube 5a is fitted around the bundle, and a fluororesin sleeve 4 is fitted onto the bundle. After fitting the fluororesin tubes 2 to the outside, they are heated all at once to bind and integrate them. The tubes 5a and the fluororesin sleeves 4 are sequentially covered with the tubes 5a and the fluororesin sleeves 4, and the tubes 5a and the fluororesin sleeves 4 are sequentially covered and heated. May be integrated. Alternatively, the tube 5a and the fluororesin sleeve 4 may be bonded together in advance.

The thus obtained fluororesin tube bundle 1 is
Fluororesin tube 2 by heating during terminal molding
Thermal expansion of the tubes 2 is suppressed by the heat-shrinkable tubes 3a fitted onto the outside of each tube 2, thereby preventing the tubes from being compressed together. Since the outward expansion pressure of the base resin tube 2 is absorbed by the tube 5a provided between the two, the fluororesin tube 2 after molding will not be crushed or deformed, and each The opening of the fluororesin tube 2 is well maintained. Therefore, when fluid flows into each fluororesin tube 2 from one end of the tube bundle 1, there is no variation in the flow rate between the tubes 2. When used in heat exchanger tubes, etc.
Enables stable deaeration and heat exchange. In addition to these uses, it is of course also possible to use it as a piping material in various fields.

Furthermore, the fluororesin tube bundle 1 of the present invention is
Since there is no need to fill the inside of the fluororesin tube 2 with filler in advance to prevent it from collapsing during manufacturing, workability during terminal molding is good, and no filler remains inside the tube 2. Therefore, it is extremely convenient when distributing high-purity liquid such as in a degassing pipe. When the fluororesin tube bundle 1 according to the present invention is used as a degassing tube, it is preferable that the fluororesin tube 2 is made of PTFE, which has particularly high gas permeability among fluororesins, and in this case, a heat-shrinkable tube is used. As 3a
Preferably, it is made of PFA. Furthermore, if a tube made of stretched continuous porous polytetrafluoroethylene resin manufactured by the method described in Japanese Patent Publication No. 51-18991, Japanese Patent Application Laid-open No. 60-104319, etc. is used, the tube Because the tube has many fine continuous pores in its wall, the differential pressure on the surface of the liquid inside the tube is greater than in a solid plastic tube where dissolved gas molecules only move between the polymer molecules that make up the tube wall. Since the gas permeability is directly applied, gas permeability is significantly increased, resulting in a significant improvement in deaeration efficiency.

In addition, in the present invention, the tube 2 is made of PTFE, which has a high coefficient of thermal expansion among various fluororesins and is difficult to fuse, so it is difficult to maintain a good opening state and integrate the tube. but instead of PTFE, PFA,
It is also possible to use materials made of tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP), ethylene-tetrafluoroethylene copolymer resin (ETFE), etc. For sleeve 4, as well as for tube 2, various fluorocarbon resins can be used. These can be selected as appropriate depending on the usage conditions of the tube bundle 1, etc.

Also, there is a heat-shrinkable tube 3a that melts and solidifies to become the joint 3, and a tube 5 that absorbs the expansion pressure of the bundle of tubes 2 and the sleeve 4 and joins them together.
As the thermofusible fluororesin constituting a,
It is possible to use PFA, FEP, ETFE, etc.
Regarding their wall thickness, the shrinkage rate of the heat shrinkable tube 3a, etc., the number of fluororesin tubes 2, the outer diameter,
Selected according to wall thickness, etc.

〔Effect of the invention〕

As explained above, according to the present invention, a heat-shrinkable tube made of a heat-melting fluororesin melts and solidifies each fluororesin tube while suppressing the expansion of the fluororesin tube, and further A tube made of heat-melting fluororesin provided between a bundle of resin tubes and a fluororesin sleeve melts and solidifies while absorbing the expansion pressure of both.
Since these fluororesin tubes and fluororesin sleeves are integrally bonded together to form a fluororesin tube bundle, there is no crushing or deformation at the tube ends, and therefore there is no difference in flow velocity between the tubes. Good performance can be obtained when used as a trachea or heat transfer tube.

In addition, since there is no need to fill the inside of the tube with filler during terminal molding, workability is improved, and since no residue remains on the inside of the tube, the original non-contaminating property of fluororesin is maintained and the transferred liquid is not contaminated. It is extremely convenient when used as a piping material.

Note that the present invention is not limited to the above embodiments, and for example, the shape of the sleeve may be changed,
Of course, various changes can be made within the technical concept of the present invention, such as increasing or decreasing the number of tubes, or performing terminal molding only on one end.

[Brief explanation of the drawing]

Fig. 1 is a perspective view with one end cut away showing an embodiment of the fluororesin tube bundle according to the present invention, Fig. 2 is a longitudinal cross-sectional side view of the end, and Fig. 3 is an end view before heating. be. 2: Fluororesin tube, 3: Joint part, 3a:
Heat shrink tube, 4: Fluorine resin sleeve, 5:
Tubular junction.

Claims (1)

[Claims] 1. A plurality of bundled fluororesin tubes,
Heat-shrinkable tubes made of heat-melting fluororesin are individually fitted onto the ends of the plurality of fluororesin tubes, contracted by heating, and further melted and solidified to join and integrate each fluororesin tube. The joint to be formed, the fluororesin sleeve fitted over the end of the bundle of fluororesin tubes, and the fluororesin sleeve provided between the fluororesin sleeve and the bundle of fluororesin tubes, A fluororesin tube bundle including a tubular joint formed by heat-melting fluororesin tubes that are melted and further solidified to join and integrate the two. 2. In the fluororesin tube bundle according to claim 1, the fluororesin tube is made of tetrafluoroethylene resin, and the joint portion and the tubular joint portion are made of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin. A fluororesin tube bundle characterized by comprising: