JP6130990B2 - Oil-repellent breathable material and method for producing the same - Google Patents

Description

  The present invention relates to an oil-repellent breathable material and a method for producing the same.

  Conventionally, for example, automotive electrical parts such as automotive lamps and ECUs (Electrical Control Units), and electrical products such as electric toothbrushes, shavers, and mobile phones, are equipped with waterproof ventilation to eliminate the pressure difference between the inside and outside of the housing. The material is used. This waterproof ventilation member is attached to the casing so as to close an opening provided in the casing, and is intended to prevent dust and waterproof while ensuring ventilation. As such a waterproof breathable material, a polytetrafluoroethylene (hereinafter referred to as “PTFE”) porous film having good air permeability and high water pressure resistance is often used.

  Although the PTFE porous membrane has a high water pressure resistance, it passes a liquid having a small surface tension such as an organic hydrocarbon such as kerosene or light oil, a low molecular weight alcohol, or a surfactant. This may not be desirable in automotive applications where oils may adhere and household applications where surfactants such as detergents may come into contact. Therefore, in these applications, it is necessary to subject the PTFE porous membrane to an oil repellent treatment as disclosed in Patent Document 1, for example.

Japanese Patent Laid-Open No. 08-206422

  By the way, when the housing to which the PTFE porous membrane is attached is made of resin, it is possible to join the PTFE porous membrane and the housing by insert molding, heat welding, ultrasonic welding, laser welding or the like. is there. However, when the casing is made of aluminum die casting or iron, it is difficult to join the PTFE porous film and the casing by welding or the like. For example, the PTFE porous film is used by using a double-sided tape or an adhesive. Will be joined to the housing. In particular, it is preferable to use a double-sided tape that can be attached to the PTFE porous membrane in advance.

  However, if the PTFE porous membrane is subjected to oil repellency, the adhesive force between the double-sided tape and the PTFE porous membrane is weak, and even if the PTFE porous membrane is joined to the housing using the double-sided tape, a high pressure load is applied. The PTFE porous membrane is easily peeled off by time and external force.

  In view of such circumstances, the present invention includes an oil-repellent breathable material that includes a PTFE porous membrane that has been subjected to an oil-repellent treatment, and that does not easily peel off even when bonded to a casing using a double-sided tape or the like. It aims at providing the manufacturing method of material.

  The inventor of the present invention, as a result of intensive research to achieve the above object, can improve the oil repellency by modifying the surface of the PTFE porous membrane subjected to the oil repellency treatment to have an appropriate elemental composition. It has been found that the adhesive force with a double-sided tape can be improved without lowering.

  That is, the present invention has a surface composed of a PTFE porous membrane subjected to oil repellent treatment, the elemental composition on the surface satisfies 0.090 ≦ O / C ≦ 0.130 and 1.03 ≦ Provided is an oil-repellent breathable material that satisfies F / C ≦ 1.40.

  Further, the present invention relates to a step of subjecting a PTFE porous membrane to an oil repellency treatment and a surface of the PTFE porous membrane subjected to the oil repellency treatment, wherein the elemental composition on the surface is 0.090 ≦ O / C ≦ 0. .130 and 1.03 ≦ F / C ≦ 1.40, and a step of etching to provide an oil-repellent ventilation material.

  According to the present invention, it is possible to obtain an oil-repellent air-permeable material that does not easily peel off even when bonded to a casing using a double-sided tape or the like.

(A) is a top view of the oil-repellent ventilation material which concerns on one Embodiment of this invention, (b) is sectional drawing of the oil-repellent ventilation material. It is a figure which shows the measuring method of adhesive force. It is a figure which shows the confirmation method of sealing performance.

  Hereinafter, embodiments of the present invention will be described.

  1 (a) and 1 (b) show an oil-repellent ventilation material 1 according to an embodiment of the present invention. This oil-repellent air-permeable material 1 has a front surface 1a and a back surface 1b, and includes a PTFE porous membrane 2 that has been subjected to oil-repellent treatment. In the illustrated example, both the front surface 1a and the back surface 1b are constituted by a PTFE porous membrane 2 that has been subjected to an oil repellent treatment. An annular double-sided tape 3 is attached to the surface 1a along the peripheral edge.

  In addition, the shape of the oil-repellent ventilation material 1 does not need to be circular as shown in FIG. 1A, and may be rectangular or polygonal, for example. Moreover, the oil-repellent breathable material 1 may include a support material excellent in breathability such as a nonwoven fabric or a mesh laminated on the PTFE porous film 2 on the back surface 1b side. In other words, the back surface 1b may be made of a support material. In this case, the oil repellent treatment to the PTFE porous membrane 2 may be performed for each support material after the PTFE porous membrane 2 and the support material are joined.

  10-500 micrometers is preferable and, as for the thickness of the oil-repellent ventilation material 1, 20-300 micrometers is more preferable.

  The elemental composition on the surface 1a of the oil repellent breathable material 1 preferably satisfies 0.090 ≦ O / C ≦ 0.130 and 1.03 ≦ F / C ≦ 1.40. In order to obtain this elemental composition, the surface of the PTFE porous membrane 2 subjected to the oil repellency treatment may be etched. However, if the etching degree is too large, the oil repellency is greatly reduced due to the decrease in fluorine, and the etching degree is reduced. If it is too small, oxygen does not increase so much and the adhesive force with the double-sided tape does not improve so much. More preferably, the elemental composition on the surface 1a satisfies 0.095 ≦ O / C ≦ 0.125 and 1.10 ≦ F / C ≦ 1.30.

  The oil repellent breathable material 1 as described above can be manufactured by the following method.

(Preparation of PTFE porous membrane)
First, a mixture obtained by adding a liquid lubricant to PTFE fine powder is formed into a sheet extending in a predetermined direction in an unfired state by at least one of an extrusion method and a rolling method to obtain a sheet-like molded body.

  The PTFE fine powder is not particularly limited, and various commercially available products can be used. For example, polyflon F104 (manufactured by Daikin Industries), full-on CD-123 (manufactured by Asahi Glass Co., Ltd.), Teflon 6J (manufactured by Mitsui / Dupont Fluorochemical Co., Ltd.) and the like can be mentioned.

  The liquid lubricant is not particularly limited as long as it can wet the PTFE fine powder and can be removed by a method such as evaporation or extraction. Examples include hydrocarbons such as liquid paraffin, naphtha, toluene, and xylene, and alcohols, ketones, esters, and fluorinated solvents. Moreover, you may use these 2 or more types of mixtures. The addition amount of the lubricant varies depending on the molding method of the sheet-like molded body, but is usually about 5 to 50 parts by weight with respect to 100 parts by weight of the PTFE fine powder.

  As an example of a method for forming a mixture obtained by adding a liquid lubricant to PTFE fine powder into a sheet extending in a predetermined direction, the PTFE fine powder added with a liquid lubricant is compressed with a cylinder and extruded with a ram extruder to form a sheet. And then rolled to a suitable thickness (usually 50 to 500 μm) with a roll pair.

  Thereafter, the sheet-like molded body containing the liquid lubricant is pre-stretched in a width direction orthogonal to the longitudinal direction of the sheet-like molded body at a temperature at which the liquid lubricant does not evaporate, usually at room temperature. The draw ratio at this time is preferably 1.5 to 20 times. The preliminary stretching may be performed in a bath filled with a liquid lubricant.

  After pre-stretching, the liquid lubricant is removed from the sheet-shaped molded body by a heating method or an extraction method, and the sheet-shaped molded body is dried.

  Next, the sheet-like molded body from which the liquid lubricant has been removed is stretched in the longitudinal direction (the predetermined direction) at a temperature equal to or higher than the melting point of PTFE. The draw ratio at this time is preferably 40 to 200 times. This is because when the magnification is lower than 40 times, the fibril length seen in the finally obtained PTFE porous membrane becomes short, the average pore diameter becomes small, and high air permeability becomes difficult to obtain. On the other hand, when the magnification is too high, the sheet-like molded body is broken, and a PTFE porous membrane cannot be obtained. A more preferable draw ratio is 60 to 160 times.

  Then, the sheet-like molded object extended | stretched to the longitudinal direction is normally extended | stretched to the width direction at 40-400 degreeC. The draw ratio at this time is preferably 3 to 40 times. The temperature during stretching is more preferably 100 to 300 ° C. in order to obtain high air permeability and to prevent breakage during stretching.

  Industrially, it is preferable that the number of steps is small, but the stretching in the longitudinal direction and the width direction may be performed in a plurality of times. Moreover, if it extends | stretches to a longitudinal direction first, the extending | stretching order and combination in the subsequent longitudinal direction or the width direction will not be restrict | limited in particular.

  The PTFE porous membrane is obtained by the above steps.

(Oil repellent treatment)
Next, the PTFE porous membrane is subjected to an oil repellent treatment. Specifically, the oil repellent treatment agent solution is applied to the PTFE porous membrane and dried. The method for applying the oil repellent treatment agent solution is not particularly limited, and for example, a spray method, a spin coating method, a dipping method, a roll coaster method, or the like can be used. When the PTFE porous membrane is immersed in the oil repellent treatment agent solution, the conditions for the immersion treatment are not particularly limited, but a temperature of 5 to 30 ° C. and an immersion time of about 2 to 60 seconds are preferable.

  The oil repellent agent concentration in the oil repellent agent solution is preferably 0.1 to 10% by weight, and more preferably 0.8 to 5.0% by weight.

  As the oil repellent agent, a fluorine-based oil repellent agent is preferable. The fluorine-based oil repellent treatment agent is preferably at least one of an acrylic polymer having a fluorine-containing side chain, a urethane polymer having a fluorine-containing side chain, and a silicone polymer having a fluorine-containing side chain. A commercial item can be used as such a fluorine type oil repellent treatment agent. For example, Unikin manufactured by Daikin, X-70-029C manufactured by Shin-Etsu Chemical, SFC Coat SIF-200 manufactured by Seimi Chemical may be used. Moreover, as a fluorine-type oil repellent agent of a silicone type polymer, there exist Shin-Etsu Chemical Co., Ltd. brand name KP-801M etc., for example.

  As the solvent used in the oil repellent solution, it is preferable to use a fluorinated solvent having high affinity for the fluorinated side chain, for example, FS thinner manufactured by Shin-Etsu Chemical Co., Ltd., Fluorinert manufactured by Sumitomo 3M Limited, or the like.

  Although the drying after application | coating of an oil repellent agent solution is not restrict | limited in particular, 40-120 degreeC heat drying is preferable. In addition, it may be air-dried or may be dried by blowing hot air.

  The oil-repellent treatment is preferably performed on the entire PTFE porous membrane, but may be performed only on one side on which etching described later is performed.

(etching)
Next, the surface (one surface in the thickness direction) of the PTFE porous membrane subjected to the oil repellent treatment has an elemental composition on the surface satisfying 0.090 ≦ O / C ≦ 0.130 and 1.03 ≦ Etching is performed so as to satisfy F / C ≦ 1.40.

  Etching may be performed by atmospheric pressure plasma method or corona discharge, but sputter etching is performed under reduced pressure or vacuum conditions from the viewpoint of stability of adhesive strength after processing and reduction of dirt adhesion to the PTFE porous film. It is preferable that

0.1-30 J / cm < ² > is preferable and, as for the energy amount at the time of performing sputter etching, 2-20 J / cm < ² > is more preferable.

  As the atmospheric gas for sputter etching, for example, a rare gas such as helium, neon, or argon can be used. Among them, it is preferable to use argon which is easily available.

  Etching may also be performed on the back surface in the thickness direction of the PTFE porous membrane (the other surface in the thickness direction).

  Through the above steps, an oil-repellent breathable material that does not easily peel off even when bonded to a housing using a double-sided tape or the like can be obtained.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not restrict | limited to these Examples at all.

(First sample)
<Examples and Comparative Examples>
20 parts by weight of a liquid lubricant (n-dodecane, manufactured by Japan Energy Co.) is uniformly mixed with 100 parts by weight of PTFE fine powder (Polyflon F-104, manufactured by Daikin Industries, Ltd.), compressed into a cylinder, and then ram extruded. A sheet-like molded body that was extruded by a machine and extended in a predetermined direction was obtained. This sheet-like molded body was rolled to a thickness of 200 μm through a metal rolling roll in a state containing a liquid lubricant. Subsequently, the liquid lubricant was removed by heating the sheet-shaped molded body to 150 ° C., and the sheet-shaped molded body was dried. The sheet-like molded body was stretched at a magnification of 4 times in the longitudinal direction at 370 ° C., and then stretched at a magnification of 4 times in the width direction at 150 ° C. to obtain a PTFE porous membrane.

  X-70-029C manufactured by Shin-Etsu Chemical Co., Ltd. was used as the oil-repellent treating agent, and this was diluted with FS thinner (manufactured by Shin-Etsu Chemical Co., Ltd.) to a concentration of 0.8% by weight to prepare an oil-repellent treating agent solution. The prepared PTFE porous membrane is completely immersed in this oil repellent treatment solution with a 20 cm square frame for about 3 seconds so as not to shrink, and then slowly pulled up and left at 120 ° C. for 5 minutes. Dried. The PTFE porous membrane subjected to the oil repellent treatment was used as the oil repellent breathable material of Comparative Example 1.

Sputter etching was performed with an energy amount of ² J / cm ^{2 on} the surface (one surface in the thickness direction) of the PTFE porous membrane subjected to the oil repellent treatment. This obtained the oil-repellent breathable material of Example 1.

Sputter etching was performed with an energy amount of 15 J / cm ^{2 on} the surface (one surface in the thickness direction) of the PTFE porous membrane subjected to the oil repellent treatment. This obtained the oil-repellent ventilation material of Example 2.

Sputter etching was performed with an energy amount of 35 J / cm ^{2 on} the surface (one surface in the thickness direction) of the PTFE porous membrane subjected to the oil repellent treatment. Thereby, the oil-repellent breathable material of Comparative Example 2 was obtained.

  Note that argon was used as the atmospheric gas for sputter etching.

<Test>
First, the elemental composition of the surface (the surface on which sputter etching was performed in Examples 1 and 2 and Comparative Example 2) was applied to all the oil-repellent ventilation materials, and the ESCA device (ULVAC) whose X-ray source was monochrome AIK _α -It measured using Phi Quantum2000). In the measurement, X-rays were irradiated with a beam diameter of 200 μm and an output of 30 W (15 kV), and the photoelectron extraction angle was 45 degrees with respect to the sample surface. The binding energy was corrected to 689.7 eV for the peak due to the C—F bond in the F1s spectrum, and the neutralization condition was a combined use of a neutralizing gun and an Ar ion gun. Then, the photoelectron intensity of the narrow scan spectrum was calculated, and the element number ratios O / C and F / C were calculated using sensitivity coefficients and the like.

Subsequently, the oil repellency of the front and back surfaces was tested for all the oil repellent breathable materials. In the oil repellency test, drop a straight-chain alkane with a dropper and check whether the paper gets wet after 1 minute with the oil repellent breathable material overlaid on the paper with the test surface facing up. did. And oil repellency was evaluated by the linear alkane with the smallest C number among the linear alkanes in which the paper was not wet. For example, if it is hexane (C ₆ H ₁₄ ), the oil repellency was expressed as C6. In Table 1, which will be described later, there is a display of C6.5, which indicates that the test was performed using a test solution in which C6 and C7 linear alkanes were mixed at a ratio of 1: 1.

  Furthermore, the thickness, air permeability, and water pressure resistance of the oil-repellent breathable materials of Comparative Example 1 and Examples 1 and 2 were measured. The air permeability was measured based on JIS P8117 (Gurley method), and the water pressure resistance was measured based on JIS L1092-B (high water pressure method).

  Next, with respect to the oil-repellent breathable material of Comparative Example 1 and Examples 1 and 2, the adhesive strength was measured and the sealing property was confirmed.

  In the measurement of the adhesive strength, as shown in FIG. 2, the back surface of the oil-repellent air-permeable material is attached to a metal plate, and an adhesive tape having a width of 19 mm (No. 4390 manufactured by Sumitomo 3M) is attached to the surface of the oil-repellent air-permeable material. I wore it. Then, using an autograph (AG-I) manufactured by Shimadzu Corporation, the adhesive tape was pulled at a speed of 300 mm / min in a state where the adhesive tape was folded 180 °, and the adhesive force was measured.

  For confirmation of sealing performance, as shown in FIG. 3, the peripheral edge of the surface of the oil-repellent air-permeable material is fixed to the SUS plate with holes with double-sided tape, and water pressure is applied from the holes of the SUS plate. The water pressure when water leaks around the double-sided tape was measured.

  The results of the above test were as shown in Tables 1 and 2.

  As can be seen from Table 2, in Examples 1 and 2 where the sputter etching was performed, the adhesive force and the sealing performance could be improved as compared with Comparative Example 1 where the sputter etching was not performed. Further, as can be seen from Table 1, the above effects could be obtained without significantly deteriorating the air permeability. Moreover, the oil repellency was significantly higher than the required quality C12 that is usually required.

  On the other hand, sputter etching was performed, but the oil repellency was greatly deteriorated in Comparative Example 2 having an elemental composition in which O / C exceeded 0.130 and F / C was less than 1.03.

(Second sample)
A porous PTFE membrane was obtained in the same manner as in the first sample except that the stretching ratio in the longitudinal direction of the sheet-like molded body was 20 times and the stretching ratio in the width direction was 5 times. This PTFE porous membrane was subjected to an oil repellent treatment in the same manner as in the first sample. The PTFE porous membrane subjected to the oil repellent treatment was used as the oil repellent breathable material of Comparative Example 3.

Sputter etching was performed on the surface (one surface in the thickness direction) of the PTFE porous membrane subjected to the oil repellent treatment with an energy amount of ² J / cm ^{2 in} the same manner as in the first sample. This obtained the oil-repellent ventilation material of Example 3.

Sputter etching was performed on the surface (one surface in the thickness direction) of the PTFE porous membrane subjected to the oil repellent treatment with an energy amount of 15 J / cm ^{2 in} the same manner as in the first sample. This obtained the oil-repellent ventilation material of Example 4.

  The same test as the first sample was performed on the oil-repellent breathable material of Comparative Example 3 and Examples 3 and 4. The test results were as shown in Tables 3 and 4.

  As can be seen from Table 4, in Examples 3 and 4 where the sputter etching was performed, the adhesive force and the sealing performance could be improved as compared with Comparative Example 3 where the sputter etching was not performed. Further, as can be seen from Table 3, the above effects could be obtained without significantly deteriorating the air permeability. Moreover, the oil repellency was also C12 or higher, which is the required quality normally required.

(3rd sample)
A porous PTFE membrane was obtained in the same manner as in the first sample except that the stretching ratio in the longitudinal direction of the sheet-like molded body was 20 times and the stretching ratio in the width direction was 15 times. This PTFE porous membrane was subjected to an oil repellent treatment in the same manner as in the first sample. The PTFE porous membrane subjected to the oil repellent treatment was used as the oil repellent breathable material of Comparative Example 4.

Sputter etching was performed on the surface (one surface in the thickness direction) of the PTFE porous membrane subjected to the oil repellent treatment with an energy amount of ² J / cm ^{2 in} the same manner as in the first sample. This obtained the oil-repellent breathable material of Example 5.

Sputter etching was performed on the surface (one surface in the thickness direction) of the PTFE porous membrane subjected to the oil repellent treatment with an energy amount of 15 J / cm ^{2 in} the same manner as in the first sample. This obtained the oil-repellent breathable material of Example 6.

  The same test as the first sample was performed on the oil repellent breathable material of Comparative Example 4 and Examples 5 and 6. The test results were as shown in Table 5 and Table 6.

  As can be seen from Table 6, in Examples 5 and 6 where the sputter etching was performed, the adhesive force and the sealing performance could be improved as compared with Comparative Example 4 where the sputter etching was not performed. Further, as can be seen from Table 5, the above effects could be obtained without significantly deteriorating the air permeability. Moreover, the oil repellency was also higher than the required quality C12 that is usually required.

(Effect of surface treatment after oil repellent treatment)
Next, in order to confirm the effect of performing sputter etching after the oil repellent treatment, the following test was performed.

  First, a PTFE porous membrane was produced in the same manner as the first sample. The PTFE porous membrane was subjected to oil repellent treatment in the same manner as in the first sample except that the oil repellent concentration in the oil repellent solution was 1.8% by weight, and the oil repellent breathable material of Comparative Example 5 was used. Obtained.

Comparative Example, except that the surface of the porous PTFE membrane (one surface in the thickness direction) was sputter-etched with an energy amount of ² J / cm ^{2 in} the same manner as the first sample before the oil repellent treatment. In the same manner as in Example 5, the oil repellent breathable material of Comparative Example 6 was obtained.

Comparative Example, except that the surface of the porous PTFE membrane (one surface in the thickness direction) was sputter-etched with an energy amount of 15 J / cm ^{2 in} the same manner as the first sample before the oil repellent treatment. In the same manner as in Example 5, the oil-repellent breathable material of Comparative Example 7 was obtained.

  For the oil-repellent breathable materials of Comparative Examples 5 to 7, the adhesive strength was measured in the same manner as in the first sample. The results are shown in Table 7.

  From Table 7, it can be seen that when sputter etching is performed before the oil repellent treatment, the adhesive strength is not improved so much.

Next, an oil-repellent breathable material of Comparative Example 8 was obtained in the same manner as Comparative Example 6 except that the concentration of the oil-repellent treating agent in the oil-repellent treating agent solution was 0.6% by weight. Moreover, the oil-repellent breathable material of Comparative Example 9 was obtained in the same manner as Comparative Example 6 except that the concentration of the oil-repellent treating agent in the oil-repellent treating agent solution was 3.0% by weight.

  For the oil-repellent breathable materials of Comparative Examples 6, 8, and 9, the air permeability and water pressure resistance were measured and the oil-repellent test was conducted. The results are shown in Table 8.

  From Table 8, it is understood that when sputter etching is performed before the oil repellent treatment, it is necessary to increase the concentration of the oil repellent treatment agent in the oil repellent treatment agent solution in order to improve the oil repellency. However, when the concentration is increased in this way, the water pressure resistance is greatly reduced. On the other hand, if the sputter etching is performed after the oil repellent treatment as in Examples 1 to 6 described above, the adhesive force can be improved without significantly reducing the oil repellency and the water pressure resistance.

DESCRIPTION OF SYMBOLS 1 Oil repellent ventilation material 1a Front surface 1b Back surface 2 PTFE porous membrane

Claims (4)

An oil- repellent breathable material composed of a polytetrafluoroethylene porous membrane that has been subjected to an oil-repellent treatment ,
To meet the polytetrafluoroethylene porous element composition on the surface of the film is 0.090 ≦ O / C ≦ 0.130 was filled and 1.03 ≦ F / C ≦ 1.40, wherein the oil repellent treatment is performed Oil repellent breathable material with improved adhesion .   The oil-repellent breathable material according to claim 1, having a thickness of 10 to 500 μm. Further comprising a wear has been double-sided tape stuck to the surface, oil repellency ventilation member according to claim 1 or 2. A method for producing an oil-repellent breathable material composed of a polytetrafluoroethylene porous film subjected to an oil-repellent treatment,
A step of subjecting the polytetrafluoroethylene porous membrane to an oil repellent treatment;
The surface of the porous polytetrafluoroethylene membrane subjected to the oil repellent treatment is such that the elemental composition on the surface satisfies 0.090 ≦ O / C ≦ 0.130 and 1.03 ≦ F / C ≦ 1.40. Etching so that the adhesive strength of the surface is improved by satisfying
Including
The said etching is a manufacturing method of the oil-repellent ventilation material which is sputter etching.

Images