JP2006008813A - Fluororesin, sliding member and sliding apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluororesin which has a low friction coefficient, is excellent in wear resistance and exerts excellent friction characteristics in the presence of a lubricant or a hydraulic oil, a modification method of the fluororesin, a sliding member and a sliding apparatus. <P>SOLUTION: The fluororesin has a structure wherein hydrogen atoms and/or fluorine atoms bonded to a carbon atom of a main backbone resin are partially substituted by oxygen-containing functional groups. The fluororesin shows an increased transmittance of visible light at a wavelength of 600 nm compared to that of the main backbone resin. The modification method of the fluororesin comprises a step wherein the hydrogen atoms and/or fluorine atoms bonded to the carbon atom of the main backbone resin are partially withdrawn to introduce unsaturated bonds and a step wherein dissociation energy of the unsaturated bonds is applied in the presence of oxygen. The sliding member and the sliding apparatus contain the fluororesin at their sliding sites. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fluororesin having both a low coefficient of friction and wear resistance. More specifically, the fluororesin is preferably used under lubrication with lubricating oil or hydraulic oil, and a sliding member and a slide using the fluororesin. It relates to a moving device.

  Conventionally, a fluororesin has been used in many sliding parts because it has a low coefficient of friction, but because of its band structure, it is inferior in wear resistance. As a measure for improving the wear resistance of such a fluororesin, it is common to add a fiber filler such as glass fiber or carbon fiber or a metal filler such as bronze. When the counterpart material is a non-ferrous metal such as an aluminum alloy, the filler promotes wear of the sliding counterpart material. On the other hand, if the addition of the filler to the fluororesin is suppressed in order to reduce such wear of the counterpart material, predetermined wear resistance cannot be obtained.

As a means for solving the above-mentioned problems, there is known a modified fluororesin that has been modified by irradiating the fluororesin with ionizing radiation in an inert gas atmosphere and heated above its melting point. (For example, refer to Patent Document 1). Since this modified fluororesin can greatly improve the wear resistance without adding a filler, it exhibits excellent sliding characteristics under dry lubrication.
However, since this modified fluororesin has low surface energy and oil repellency like ordinary fluororesins, oil film formation is suppressed in the presence of lubricating oil and hydraulic oil, and a sufficient friction coefficient reducing effect is obtained. Absent.

Thus, even if the abrasion resistance of the fluororesin is improved, since the fluororesin has low surface energy and exhibits oil repellency, oil film formation is inhibited in the presence of the lubricating oil and hydraulic oil, and the lubricating oil and hydraulic oil The fluid lubrication effect due to is difficult to express.
On the other hand, as a technique for improving the wettability with the lubricating oil and the hydraulic oil, a functional group containing monomers other than those constituting the fluororesin, such as corona treatment, RF bombardment treatment or DC bombardment treatment (see, for example, Patent Document 2). (For example, refer to Patent Document 3), plasma treatment, and the like are known.
JP-A-11-116624 International Publication No. 98/44026 JP 2001-208249 A

However, in any of the above methods, a special process for increasing the surface energy is required, which causes a problem that the cost is increased.
In addition, if the fluorine resin reforming method by ionizing radiation treatment described above and the wettability improving method for lubricating oil and hydraulic oil are used in combination, the fluororesin exhibits excellent friction characteristics in the presence of lubricating oil and hydraulic oil. Although it is theoretically possible to manufacture the two, two kinds of manufacturing processes must be added, and the present situation is that they are not put into practical use due to the cost.

  The present invention has been made in view of such problems of the prior art, and its object is to have both a low coefficient of friction and excellent wear resistance in the presence of lubricating oil and hydraulic oil. An object of the present invention is to provide a fluororesin that exhibits excellent frictional characteristics, a method for modifying the fluororesin, a sliding member and a sliding device using the fluororesin.

  As a result of intensive studies to achieve the above object, the present inventors have found that the above object can be achieved by introducing a predetermined oxygen-containing functional group by appropriate unsaturated bond introduction treatment, etc. It came to complete.

  That is, the fluororesin of the present invention is a fluororesin formed by replacing part of hydrogen atoms and / or fluorine atoms bonded to carbon atoms of the main skeleton resin with oxygen-containing functional groups, and visible light at a wavelength of 600 nm. The transmittance is higher than that of the main skeleton resin.

Further, the fluororesin modification method of the present invention is a fluororesin modification method,
It has a step of extracting a part of hydrogen atoms and / or fluorine atoms bonded to carbon atoms of the main skeleton resin to introduce unsaturated bonds, and a step of imparting dissociation energy of unsaturated bonds in the presence of oxygen. And

  Furthermore, the sliding member of the present invention is characterized by containing the fluororesin as described above in the sliding portion, and the sliding device of the present invention further includes a sliding member provided with such a sliding member. The apparatus is characterized in that the sliding member slides in the presence of lubricating oil or hydraulic oil.

According to the present invention, since a predetermined oxygen-containing functional group is introduced by appropriate unsaturated bond introduction treatment, etc., it has both a low friction coefficient and excellent wear resistance, and in the presence of lubricating oil / hydraulic oil. A fluororesin exhibiting excellent friction characteristics, a method for modifying the fluororesin, a sliding member and a sliding device using the fluororesin can be provided.
That is, a fluorine resin in which a part of the hydrogen atom or fluorine atom bonded to the carbon atom of the main skeleton resin is substituted with an oxygen-containing functional group and the visible light transmittance at a wavelength of 600 nm is increased as compared with the main skeleton resin is slid. By using it as a moving member, good friction characteristics can be realized in the presence of lubricating oil and hydraulic oil.
Furthermore, according to the present invention, it is possible to produce a fluororesin that exhibits good friction characteristics in the presence of lubricating oil and hydraulic oil by adding only the ionizing radiation irradiation process. There is also an advantage that the investment for improving the dynamic characteristics can be inexpensive.

Hereinafter, the fluororesin of the present invention will be described in detail. In the present specification, “%” represents mass percentage unless otherwise specified.
As described above, the fluororesin of the present invention is a fluororesin having a structure in which a hydrogen atom bonded to a carbon atom of the main skeleton resin and / or a part of the fluorine atom is substituted with an oxygen-containing functional group at a wavelength of 600 nm. The visible light transmittance is higher than that of the main skeleton resin.

  Here, examples of the main skeleton resin include various fluororesins. However, since the fluororesin of the present invention is used for sliding applications, the main skeleton resins are excellent in sliding characteristics among these fluororesins. It is preferable to use a resin, and specifically, one or more of tetrafluoroethylene resin, perfluoroethylene polypropylene resin, perfluoroalkoxy resin, and vinylidene fluoride resin are desirable.

The oxygen-containing functional group substituted with at least one of the hydrogen atom bonded to the carbon atom of the main skeleton resin and a part of the fluorine atoms may be any functional group containing an oxygen atom, but a hydroxyl group, a carbonyl group, Examples thereof include a carboxyl group, a ketone group, and an ether group.
Both hydrogen atoms and fluorine atoms may be substituted with oxygen-containing functional groups, and all the corresponding hydrogen atoms may be substituted, but at least one fluorine atom must remain, and the main skeleton All of the fluorine atoms bonded to the carbon atoms of the resin are not substituted.
For convenience of explanation, the term “substitution” is used, but the meaning is not limited to that caused by the substitution reaction, and substitution by addition reaction is included in the scope of the present invention.

By introducing such oxygen-containing functional groups, the wettability of the obtained fluororesin with lubricating oil or hydraulic oil is improved.
For example, by introducing an oxygen-containing functional group, the surface energy of the obtained fluororesin can be 20 to 40 dyn / cm, preferably 25 to 35 dyn / cm.
Generally, since the surface energy of lubricating oil and hydraulic oil is 25 to 35 dyn / cm, the surface energy of the fluororesin is 20 to 40 dyn / cm, preferably 25 to 35 dyn / cm. The wettability of the fluororesin with respect to the lubricating oil / hydraulic oil can be greatly improved, and the suppression of oil film formation due to the wettability can be avoided even in the presence of the lubricating oil and / or hydraulic oil.

The fluororesin of the present invention has a visible light transmittance at a wavelength of 600 nm that is higher than the visible light transmittance of the main skeleton resin.
The increase in visible light transmittance is a phenomenon caused by the reduction in the crystal size of the fluororesin after irradiation with ionizing radiation, as will be described later.
When the sliding member using the fluororesin of the present invention slides, the crystal size is reduced, so that the size of the wear powder is smaller than that of the conventional fluororesin and the fluidity of the crystal is increased. Transfer to the mating material is facilitated, and generation of a transfer film is promoted to cause sliding between the fluororesins, so that wear as the fluororesin itself is reduced.

In addition, the fluororesin of the present invention can be used as a solid lubricant, and in this case, it is preferable to add to other resins at a ratio of 5 to 70%.
If the addition amount is less than 5%, sufficient friction characteristics cannot be obtained. On the other hand, even if the addition amount is increased more than 70%, the effect of improving the friction characteristics is saturated, and a further improvement effect of the friction characteristics can be obtained. Absent.

Next, the method for modifying the fluororesin of the present invention will be described.
As described above, the method for modifying a fluororesin of the present invention is a method for producing the above fluororesin, in which a hydrogen atom bonded to a carbon atom of the main skeleton resin and / or a part of the fluorine atom is extracted and unsaturated. A step of introducing a bond and a step of imparting dissociation energy of an unsaturated bond in the presence of oxygen.

Here, the step of introducing an unsaturated bond is not particularly limited, but an oxygen concentration of 10 Torr or less is present without the presence of components other than the main skeleton resin and the same monomer (for example, other polymers). It is desirable to irradiate with ionizing radiation in the range of 1 to 10 kGy in an active gas atmosphere and in a state of being heated to the melting point of the main skeleton resin or higher.
In this case, if the oxygen concentration exceeds 10 Torr or the heating temperature is lower than the melting point of the main skeleton resin, the main skeleton resin is selectively broken without forming an unsaturated bond. The resin itself may decompose.
Moreover, when the intensity of ionizing radiation is less than 1 kGy, the formation of unsaturated bonds is suppressed. On the other hand, when the intensity of ionizing radiation exceeds 10 kGy, decomposition of the main skeleton resin itself may be promoted.
The ionizing radiation is not particularly limited, and α rays, proton rays, heavy ions, β rays, X rays, γ rays, neutron rays, and the like can be used.

On the other hand, in the step of dissociating the unsaturated bond, it is desirable to give the dissociation energy of the unsaturated bond as thermal energy under the condition of an oxygen partial pressure of 13.3 kPa or more, but it is not particularly limited.
In this step, the unsaturated bond introduced into the main skeleton resin is dissociated and reacts with an oxygen atom to change into an oxygen-containing functional group such as a hydroxyl group, a carbonyl group, a carboxyl group, a ketone group, and an ether group. This produces a fluororesin.
When the oxygen partial pressure is less than 13.3 kPa, the chemical reaction between the unsaturated bond and the oxygen atom may be suppressed, and a sufficient amount of oxygen-containing functional group may not be formed. The wettability with the lubricating oil and / or hydraulic oil may not be improved much.

In the present invention, it is also possible to supply the thermal energy applied in the unsaturated bond dissociation step when mixing with the main skeleton resin or during resin molding.
That is, as described above, the precursor of the fluororesin of the present invention obtained by introducing an unsaturated bond into the main skeleton resin is used as a raw material for resin molding, and is given heat energy and mixed with the main skeleton resin. In addition, it is possible to perform molding, and thus it is possible to complete the molding simultaneously with the production of the fluororesin of the present invention and obtain a resin molded product made of the fluororesin of the present invention.
Thus, the compound obtained by introducing an unsaturated bond into the main skeleton resin is a precursor of the fluororesin of the present invention, and functions as a molding raw material as it is in a molding process involving heating.

  The molding method in which the fluororesin precursor of the present invention can be used as a molding raw material is not particularly limited as long as heat treatment is performed, and examples thereof include injection molding, ram molding, and compression molding. Can do.

In the present invention, the introduction of unsaturated bonds and the dissociation of unsaturated bonds described above can be confirmed from the analysis results of FT-IR (Fourier transform infrared spectrophotometer) shown in Table 1 below.
That is, when ionizing radiation is irradiated, the peak area of the peak attributed to the unsaturated bond increases, and when the dissociation process of the unsaturated bond is further performed, the increased peak area decreases. Formation and dissociation are confirmed.

Through the above steps, the surface energy of the fluororesin obtained is 20 to 40 dyn / cm, preferably 25 to 35 dyn / by replacing part of the hydrogen atom or fluorine atom bonded to the carbon atom with an oxygen-containing functional group. cm.
Generally, since the surface energy of lubricating oil and hydraulic oil is 25 to 35 dyn / cm, the surface energy of the fluororesin is set to 20 to 40 dyn / cm, preferably 25 to 35 dyn / cm. The wettability of the fluororesin with respect to the hydraulic oil is greatly improved, and oil film formation is not suppressed due to the wettability even in the presence of lubricating oil and / or hydraulic oil.

On the other hand, as described above, when the main skeleton resin is irradiated with ionizing radiation in the range of 1 to 10 kGy in an inert gas atmosphere having an oxygen concentration of 10 Torr or less and heated to the melting point or higher, unsaturated bonds are formed. Simultaneously with the generation, the crystal size is reduced.
Specifically, as shown in FIG. 1, the visible light transmittance increases after irradiation with ionizing radiation, so that it can be confirmed that the crystal size is reduced.

When the crystal size is reduced, when the fluororesin is slid, the size of the wear powder is reduced, and the flowability of the crystal is increased to facilitate transfer to the counterpart material. Since the generation is promoted to cause sliding between the fluororesins, wear of the fluororesin itself is reduced.
In addition to this, the wear resistance of the fluororesin is also improved by forming a crosslinked structure in the molecular chain of the fluororesin by irradiation with ionizing radiation.
In order to sufficiently improve the wear resistance by reducing the crystal size as described above, it is preferable that the visible light transmittance at a wavelength of 600 nm is 10% or more. There is a case that the size is not sufficiently reduced and sufficient wear resistance cannot be obtained.

Next, the sliding member and the sliding device of the present invention will be described.
The sliding member of the present invention is obtained by applying the above-described fluororesin of the present invention to a sliding part. The sliding part contains the fluororesin of the present invention in a proportion of 5 to 70%. Preferably it is.
If the content of the fluororesin is less than 5%, the effect of improving the friction due to the addition of the fluororesin is not sufficiently exhibited, and if it exceeds 70%, molding may be difficult.

Further, as described above, the fluororesin of the present invention has improved wettability with respect to the lubricating oil / hydraulic oil, so that the sliding member of the present invention is also suitable for use in the presence of the lubricating oil / hydraulic oil. However, in this case, it is desirable that the surface roughness of the sliding surface of the sliding member is Rz = 10 μm or less, preferably Rz = 5 μm or less.
When the surface roughness Rz of the sliding partner material exceeds 10 μm, the fluororesin of the present invention is inhibited from being transferred to the sliding surface of the counterpart material, and the friction coefficient reducing effect is not manifested. Sometimes.

The sliding device of the present invention is a device provided with the sliding member of the present invention, and slides this sliding member in the presence of lubricating oil or hydraulic oil.
About the suitable surface roughness of a sliding other material, it is the same as that of the case of the said sliding member.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these Examples.

Example 1
As fluororesin (main skeleton resin), tetrafluoroethylene which is excellent in low friction among fluororesins is used, and this molding powder (product name: G163, manufactured by Asahi Glass Co., Ltd.) has an oxygen concentration of 1 Torr and a nitrogen concentration of 800 Torr. An unsaturated bond is introduced by irradiating an electron beam (pressurized voltage 2 MeV) at a radiation dose of 100 kGy under heating conditions of ° C. to obtain a target fluororesin precursor, and then the average particle size is about 20 μm. Until pulverized with a jet mill.
After 10% of the fluororesin (fluororesin precursor) subjected to the above unsaturated bond introduction treatment is added to 90% of the fluororesin (G163) as the main skeleton resin, and this powder mixture is sufficiently mixed with a mixer , Heat treatment at 300 ° C. for 12 hours to remove high-temperature volatile components, and obtain a fluororesin mixture, that is, a mixture of an example of the fluororesin of the present invention and a main skeleton resin. Then, the obtained fluororesin mixture is molded to 50 MPa. Was preformed into a cylindrical shape with pressure and then fired in an electric furnace at a temperature of 350 to 400 ° C. for 3 hours. The obtained fluororesin molding was processed with a lathe to produce a ring test piece 10 having a straight joint 20 shown in FIG.

(Example 2)
To 70% of the fluororesin (G163), 30% of a fluororesin into which an unsaturated bond was introduced was added in the same manner as in Example 1, and processed into a ring specimen as in Example 1.

Example 3
10% of fluororesin (G163) 60%, fluororesin 30% introduced with unsaturated bonds in the same manner as in Example 1, and polyamideimide powder (trade name Torlon 4203L average particle size 15 μm, manufactured by Amoco) % Was added. Then, it processed into the ring test piece like Example 1. FIG.

(Comparative Example 1)
A fluororesin (G163) was preformed into a cylindrical shape at a molding pressure of 50 MPa, and then fired at a temperature of 350 to 400 ° C. for 3 hours in an electric furnace. The obtained fluororesin molding was processed into a ring test piece in the same manner as in Example 1.

(Comparative Example 2)
Corona treatment was performed on the fluororesin in the air at 200 W · min / m ² to give a functional group to the fluororesin. After performing the corona treatment, it was preformed into a cylindrical shape at a molding pressure of 50 MPa, and then fired at a temperature of 350 to 400 ° C. for 3 hours in an electric furnace. The obtained fluororesin molding was processed into a ring test piece in the same manner as in Example 1.

(Comparative Example 3)
Corona treatment was performed on the fluororesin in the air at 200 W · min / m ² to give a functional group to the fluororesin. 70% corona-treated fluororesin, 20% graphite powder (trade name SGL 3 μm, manufactured by ESC Corporation), carbon fiber (trade name Kureha Chop M-2007S, trade name Kureka Chop M-2007S, fiber diameter 14.5 μm, fiber length 90 μm ) 10% was added and the mixture was mixed well with a mixer.
Subsequently, it was preformed into a cylindrical shape at a molding pressure of 50 MPa, and then fired at a temperature of 350 to 400 ° C. for 3 hours in an electric furnace. The obtained fluororesin molding was processed into a ring test piece in the same manner as in Example 1.

[Performance evaluation]
(Contact angle measurement and surface energy calculation)
About the test piece of Examples 1-3 and Comparative Examples 1-3, the contact angle measurement with a pure water and a methylene iodide was performed, and the surface energy was computed from this measured value. The obtained results are shown in Table 2.

  As shown in Table 2, in the test pieces of Examples 1 to 3, the surface energy was remarkably increased as compared with the test pieces of Comparative Examples 1 to 3, and the unsaturated bond introduction treatment according to the present invention and the test piece were not. It was found that a part of the hydrogen atom or fluorine atom bonded to the carbon atom of the main skeleton resin was substituted with an oxygen-containing functional group in combination with the dissociation treatment of the saturated bond.

(Sliding characteristics improvement effect)
About the test piece of Examples 1-3 and Comparative Examples 1-3, the friction test was done in the following way using the hydraulic fluid for automatic transmissions (made by Idemitsu Kosan Co., Ltd., brand name Matic J).
An aluminum die-cast material (ADC-12) was selected as the mating material for sliding contact. In addition, this aluminum die-cast material was processed into a disk 25 to be attached to the vertical pin-on-disk type friction and wear tester shown in FIG. 3, but the shape was 60 mm in diameter and 10 mm in thickness. The surface roughness was about Ra = 10 μm.

Here, the friction tester shown in FIG. 3 will be described. This tester has a ring holder 21 in the upper part, and this ring holder 21 is a spring of a snap ring 22 installed on the inner peripheral surface 17a side of the ring test piece. The ring test piece outer peripheral surface 17b is pressed against and fixed to the holder groove by force, so that the ring test piece 10 does not move in the radial direction during sliding.
On the other hand, the lower part of the testing machine has a disk holder 26 coupled to the rotating shaft 27, and when the disk 25 is fixed to the disk holder 26 with bolts, the disk 25 is rotatable with respect to the ring test piece 10. Next, the ring holder 21 is lowered to bring the ring test piece 10 and the disk 25 into a sliding contact relationship, and by further applying pressure P from the axial direction of the ring holder 21, the ring test piece 10 and the disk 25 are pressed against each other. Let At this time, the sliding contact portion between the ring test piece 10 and the disk 25 is immersed in the automatic transmission hydraulic oil (matic J) 28.

  FIG. 4 and Table 3 show the results of a wear test conducted using the above-described testing machine under the test conditions of pressure contact surface pressure: 5 MPa, friction speed: 10 m / sec, test time: 6 hours.

From FIG. 4, the test pieces of Examples 1 to 3 can continue the friction test for 6 hours, and the friction coefficient during the test is almost stable, whereas the test pieces of Comparative Examples 1 to 3 are It can be seen that abnormal wear of the ring specimen occurred during the test.
In addition, when Example 1 and Example 2 are compared, the friction coefficient decreases as the addition amount of the fluororesin subjected to the combination of the unsaturated bond introduction process and the unsaturated bond dissociation process according to the present invention is increased. It turns out that there is a tendency. In addition, as shown in Table 2, the effect of reducing the friction coefficient is manifested by the improvement of the wettability with the lubricating oil and the hydraulic oil due to the increase of the surface energy and the oil film generation ability is improved. it is conceivable that.
On the other hand, for Example 3, by adding PAI powder excellent in wettability with lubricating oil or hydraulic oil to the fluororesin having improved wettability as described above, the formation of an oil film is further promoted, and the coefficient of friction is increased. Has fallen.

Table 3 shows the measurement results of the wear amount of the ring test piece and the disk test piece after completion of the friction test, but in Examples 1 to 3, the wear powder accompanying the addition of the crosslinked structure and the reduction of the crystal size is shown. It can be seen that the amount of wear of the ring specimen is remarkably reduced by the reduction.
On the other hand, for Comparative Examples 1 to 3, abnormal wear occurred in a relatively short time (typically about 1 hour) from the start of the test because the test conditions themselves exceeded the PV limit of a general fluororesin. .

It is a graph which shows the change of visible light transmittance | permeability at the time of implementing the introduction process of the unsaturated bond which concerns on this invention, and the dissociation energy provision process of an unsaturated bond with respect to tetrafluoroethylene resin. It is a perspective view which shows the shape of the ring test piece used for the friction test. 1 is a schematic view of a vertical ring-on-disk friction and wear tester used for a friction test. FIG. It is a graph which shows a time-dependent change of a friction coefficient.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Ring test piece 20 Joint 21 Ring holder 22 Snap ring 23 Torque detector 24 Load cell 25 Disk 26 Disk holder 27 Rotating shaft 28 Hydraulic oil for automatic transmission

Claims (15)

  A part of hydrogen atoms and / or fluorine atoms bonded to carbon atoms of the main skeleton resin is substituted with an oxygen-containing functional group, and the visible light transmittance at a wavelength of 600 nm is higher than that of the main skeleton resin. Characteristic fluororesin.   2. The fluororesin according to claim 1, wherein the visible light transmittance at a wavelength of 600 nm is 10% or more.   Surface energy is 20-40 dyn / cm, The fluororesin of Claim 1 or 2 characterized by the above-mentioned.   The fluororesin according to any one of claims 1 to 3, wherein the main skeleton resin comprises a tetrafluoroethylene resin, a perfluoroethylenepropylene resin, a perfluoroalkoxy resin, or a vinylidene fluoride resin.   The precursor of the fluororesin according to any one of claims 1 to 4, wherein an unsaturated bond is introduced by extracting a part of a hydrogen atom and / or a fluorine atom bonded to a carbon atom of the main skeleton resin. A fluororesin precursor characterized by comprising: A method for producing a fluororesin according to any one of claims 1 to 4,
It has a step of extracting a part of hydrogen atoms and / or fluorine atoms bonded to carbon atoms of the main skeleton resin to introduce unsaturated bonds, and a step of imparting dissociation energy of unsaturated bonds in the presence of oxygen. A method for modifying a fluororesin.   The method for modifying a fluororesin according to claim 6, wherein in the step of introducing the unsaturated bond, the main skeleton resin and the monomer are not added except for the same component.   The method for modifying a fluororesin according to claim 6 or 7, wherein the dissociation energy of the unsaturated bond is applied at an oxygen partial pressure of 13.3 kPa or more.   The method for reforming a fluororesin according to any one of claims 6 to 8, wherein the dissociation energy of the unsaturated bond is given by thermal energy.   The method for reforming a fluororesin according to claim 9, wherein the thermal energy is applied at least one of a mixing step and a molding step of the fluororesin.   The method for modifying a fluororesin according to claim 10, wherein a molding method applied to the molding is injection molding, ram molding, or compression molding.   A sliding member comprising the fluororesin according to any one of claims 1 to 4 in a sliding part.   The sliding member according to claim 12, wherein the content of the fluororesin in the sliding part is 5 to 70%.   14. A sliding device comprising the sliding member according to claim 12 or 13, wherein the sliding member slides in the presence of lubricating oil or hydraulic oil.   The sliding device according to claim 14, wherein the sliding member slides with a mating member having a surface roughness of a sliding portion of Rz = 10 μm or less.

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