MXPA97001117A

MXPA97001117A - Procedure to increase the capacity of humectation of a porous body and device for labor in practice of procedimie

Info

Publication number: MXPA97001117A
Application number: MXPA/A/1997/001117A
Authority: MX
Inventors: Chavatte Philippe; Duez Jose; Goudmand Pierre; Bedhome Vincent; Dessaux Odile; Quensierre Jeandenis
Original assignee: Conte
Priority date: 1996-02-12
Filing date: 1997-02-11
Publication date: 1998-04-01

Abstract

A method for homogeneously increasing the wetting capacity of a porous body in relation to a fluid comprises a step in which the porous body (20) is subjected to a plasma in a treatment vessel (12, 14, 16). of nitrogen, generated by an electromagnetic wave discharge on a nitrogen gas, is mainly used to increase the wetting capacity of a marking tip

Description

PROCEDURE TO INCREASE THE CAPACITY OF HUMECTATION OF A POROUS BODY AND DEVICE FOR THE IMPLEMENTATION OF THE PROCESS The present invention relates to a method for increasing the wetting ability of a porous body with respect to a fluid and a device for its implementation. In many industrial applications, it is sought to significantly increase the wetting capacity of porous bodies, that is to say, their hydrophilic nature, with respect to liquids or gases. We now use different procedures nowadays. It is known, for example, to moisten the porous body to be treated in a bath that contains t-surfactants; then heat the porous body in order to evaporate the water enclosed in the porous body. The procedure is tedious in its implementation and requires heating of the porous body, which may cause undesirable changes in its structure or in its form, since said body is constituted by materials of relatively low melting point. . When the porous body is made from molded powders, primarily by sintering, the mixture in the powders is known (solid surfactant, also in powder form, or the use of already treated powders to make them hydrophilic). .

However, during the production of the porous body from said powders, it is necessary to heat them to obtain cohesion of the porous body. Thus, during a sintering process, temperatures of the order of 200 to 50 ° C are usually reached. Such heating has the effect of altering the hydrophilic nature of the powders and the properties of the surfactants. The present invention has the purpose of solving the drawbacks mentioned above and to propose a method for directly treating the already formed porous bodies, without having to heat them. In the process according to the invention, the porous body is subjected, in a treatment vessel, to a nitrogen plasma, generated by a discharge of electomagnetic waves, on gaseous nitrogen. Said process is characterized in that the nitrogen plasma, in the treatment vessel, is a nitrogen plasma in the post-nonionic remote discharge. The nitrogen-containing plasma ob-temped is used, in such a way, to increase the wetting capacity in a homogeneous manner, in a porous body, with respect to fluids. The use of nitrogen retarded plasmas is known to increase the adhesion of surfaces of polyester materials, primarily polypropylene. One such use is described in European patent 38 401 329.3. Surprisingly, the nitrogen plasma penetrates into the interior of the porous body; The free nitrogen atoms are therefore not deactivated, which allows the porous body to be treated in its mass and rendered homogeneous hydrophilic. This treatment procedure allows to avoid any temperature rise of the porous body. Finally, contrary to what the text If) entitled "Plasma froí dans la fab i cation des aten aux" ("Cold Plasma in the Manufacturing of Materials") by F. F. Gpll, IEEE Press, Inc., New York, page 156, 1993, no deposit is formed inside the porous body nor is it clogged, which has The advantage of not modifying the dimensions of the pores of the body thus treated. In the aforementioned book, the treatment of the porous body by cold helium plasma or oxygen is aimed at reducing the size of the pores on the surface of the body, with the intention of sealing them. Concomitantly, even bodies of very low porosity, of the order of 1 urn can be treated by the process according to the invention, without affecting its porous nature. Preferably, the gaseous nitrogen comprises a proportion of oxygen comprised between 1% and 5% of the total pressure of the gas. The contamination of nitrogen gas by oxygen allows the action of the nitrogen plasma to be further improved. on the porous body. The nitrogen plasma in the treatment room is a nitrogen plasma of non-ionic post-discharge far away. b fll carry out the t ation in a container that is relatively distant from the discharge zone in which the plasma is generated, a large treatment container can be used, which allows the simultaneous treatment of many porous bodies. Preferably, the temperature inside the treatment vessel is substantially equal to the ambient temperature. According to an advantageous embodiment of the invention, the porous body is composed of fritted powders. In the process according to the invention, the plasma penetrates the porous body to a depth of the order of 10 an. The process according to the invention allows, in this way, to treat the product in its final form and structure. The hydrophilic nature of the porous body, therefore, is not altered by the subsequent stages of f-abpcation. According to another aspect of the invention, a device for the implementation of the method comprises: b means for providing a nitrogen gas in a cavity of c ga; means for introducing an electromagnetic wave into the discharge cavity and generating a nitrogen plasma; and means forming a container for containing the porous body to be treated and plasma nitrogen. Other features and advantages of the invention will appear further on in the description that follows. In the attached drawings, which are given by way of non-restrictive examples: Figure 1 is a diagram illustrating a device according to an embodiment of the invention. Figure 2 is a sectional view, taken along the line JI-II of Figure 1. Figure 3fl is a sectional view illustrating the wettability of a porous body treated by a method of the prior art; and Figure 3B is a sectional view, similar to Figure 3A, of a porous body treated by the process according to the invention. Firstly, with reference to FIG. 1, a device according to an embodiment of the invention for the implementation of a method for increasing the wetting capacity of a porous body 20 will be described with reference to FIG. to a fluid. The device comprises means 10, 11 for providing a nitrogen gas in a discharge cavity 12.

Preferably, the nitrogen gas comprises a low oxygen content, of the order of 1 to 5 percent of the total gas pressure. A source of nitrogen gas 10 and a source of oxygen 5 are thus connected to the discharge cavity 12. The means 13, 14 for introducing an electromagnetic wave into the discharge cavity 12. , they comprise a wave generator 14 which, by means of a magnetron, allows produce an electromagnetic wave in the decarbon cavity 12. The range of frequencies that can be used is very large; Generally, microwave frequencies of the order of 880 to 915 MHz or 2450 MHz are selected. lower frequencies, on the order of 13.56 MHz, 27.12 MHz or 433 MHz, can be used in the same way. A waveguide tube is provided between the outlet of the generator 14 and the discharge cavity 12. A water circulator 13 is provided around this waveguide tube to cool it. It is provided with a container or enclosure 15 par-a introducing the plasma, in a deferred manner in relation to the discharge area, into a treatment vessel 16, capable of containing the porous body to be treated. • > (extends on the cavity "discharge chute 12 and the treatment container 16.

As illustrated in Figure 2, the treatment vessel 16 comprises a rotating reactor 17 in which the porous bodies 20 to be treated are agitated. A large number of bodies 20 can be treated if desired. The reactor 17 is rotated in a known manner by a motor 18, allowing the internal projections 17a with respect to the reactor to agitate the porous bodies 20. A hatch 16a is provided in a face of the treatment vessel 16, which has the purpose of introducing and removing the products in t ation. As best illustrated in FIG. 1, by means of the different arrows, the nitrogen deferred plasma passes through the treatment vessel 16 and the reactor 17 and is then recovered by a group (Je pumping 19. Said gr Pumping 19 allows a depression to be created in the treatment vessel, so that the nitrogen plasma is sucked into the treatment vessel 16. When the method according to the invention is put into practice, by means of the device described in FIG. above, the porous body 20 is subjected to a cold deferred nitrogen plasma in the treatment vessel 16, that is, to a nitrogen plasma in the far nonionic after-discharge, the porous body 20 may be composed of fritted powders. , such as, for example, filled polyethylene or polypropylene powders, can be composed of one or more polumeric materials or mixed materials, said porous bodies are generally obtained by fiber at a temperature of the order of 200 ° C. The powders used frequently have a granulometry between 1 and 1000 pin; the porous bodies then having a porosity within the range of 1 to 50 p.m. Other porous bodies 20 can also be treated effectively by the process according to the invention; as it happens, principally, by way of non-restrictive examples, with textile fibers, natural or synthetic, of the acrylic, polyester type, the various plastics, ceramics, etc. In an application of said process, the porous body 20, such as the one illustrated in section in Figure 3B, is a writing tip of a marker; said tip is suitable for contacting an ink tank. Said felt tips or markers are generally manufactured by sintering from polyethylene or polypropylene powders, as explained above. In Figures 3fl and 3B the ink is shown in thick line inside the pores of the porous body 20. It is then seen that, as a result of the method according to the invention, the tip 20 shown in Figure 3B is made wettable in a homogeneous way and in all its mass. On the other hand, the tip 20 illustrated in section in FIG. 3fl, treated by means of a classical method, does not exhibit the hydrophilic nature in a homogenous manner in its ma. The ink does not penetrate the pores of the body 20 of Figure 30 more than superficially; while at the tips treated by means of the process according to the invention, the ink is absorbed in the pores of the tip, even in its center (see Figure 3B). Another use of the process according to the invention consists in treating filtration membranes, mainly for the subsequent implementation of selectors. The process according to the invention can also be used to treat, as they are porous bodies, electrolysis or electrophoresis membranes. It should be understood that numerous modifications can be made to the examples described above, without departing from the scope of the invention.

Claims

NOVELTY OF THE INVENTION CLAIMS

1. - Method for homogeneously increasing the wetting capacity of a porous body (20) in relation to a fluid, in which said porous body (20) is subjected in a treatment vessel (12, 15, 16) to a plasma of nitrogen generated by means of an electromagnetic wave discharge on a nitrogen gas, characterized in that said process because the nitrogen plasma present in the treatment vessel (16) is a far nonionic post-discharge plasma.

2. Method according to claim 1, further characterized in that the nitrogen gas comprises a proportion of oxygen that is between 1 and 5% of the total gas pressure.

3. Method according to any of claims 1 or 2, further characterized in that the temperature inside the treatment vessel (15, 16) is substantially equal to the ambient temperature. 4 - Process according to any of claims 1 to 3, further characterized in that the porous body is composed of one or more poly erial materials or x to. 5. Method according to any of claims 1 to 4, further characterized in that the porous body (20) is composed of fritted powders. 6. Method according to any of claims 5, further characterized in that the porous body (20 comprises full polyethylene) 7.- Method according to any of claims 1 to 5, characterized in that the body -0 (20) bought polyphenylene polyethylene. - Method of conformity with any of the other indications 7, characterized in that the plasma penetrates the porous body to a depth of 10 cm. according to any of claims 3, further characterized in that the porous body (20) is composed of textile fibers 10. Method according to any of claims 9, further characterized by the porous body (20) it has a porosity comprised between 1 and 50 μm 11. Device for putting into practice the method according to any of claims 1 to 10, characterized in that it comprises: means (10, 11) for providing a nitrogen gas in a discharge cavity (12); means (13, 14) for introducing an electromagnetic wave in said cavity (Je discharges (12) and generating a plasma (Je nit r-eno; and means forming the container (12, 15, 16) for con in r the porous body (20) to be treated and the nitrogen plasma 12. Device according to claim 11, further characterized in that it comprises a container (15) extending between the discharge cavity (12). 12) and a treatment vessel (16), adapted to introduce the nitrogen plasma into the treatment vessel (16) 13. Device according to claim 12, further characterized in that the treatment vessel (16) comprises a rotating reactor (17) in which several porous bodies (20) are stirred to be treated. 1

4. The use of the method according to any of claims 1 to 10, characterized in that said porous body is a writing tip of a marker; said tip being suitable for contacting a depositor. 1

5. The use of the method according to any one of claims 1 to 10, characterized in that said porous body is a filtration membrane 1

6. The use of the method according to any of claims 1 to 10, characterized because said porous body is an electrolysis membrane or an electrophoresis membrane.