JPH115813A - Low molecular weight fluorine-containing resin powder and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain low molecular weight fluorine-containing resin powder excellent in lubricating property, water-repelling and oil-repelling property, etc., and provide a method for producing the powder. SOLUTION: This low molecular weight fluorine-containing resin powder is obtained by cooling reaction-produced gas of melted fluorinecontaining resin with fluorine gas and completely fluorinated and has 700-4,000 molecular weight. The powder does not moisten with acetone and has high water-repelling and oil-repelling property. This method for producing the resin powder comprises retaining fluorine concentration in atmospheric gas to >=0.1 vol.% until the atmospheric temperature becomes <=50 deg.C from a reactor to a recovering vessel in a method for heating the fluorine containing resin powder in the temperature range from a melting point of the resin powder to 600 deg.C to melt the resin, subjecting the melted resin powder to contact reaction with at least one kind of molecular fluorine, nitrogen trifluoride, halogen fluoride and fluoride of rare gas, cooling gas produced by reaction to <=50 deg.C by a cooler and recovering the particles of the deposited low molecular weight fluorine-containing resin by a recovering vessel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low molecular weight fluorine-containing resin powder having excellent water and oil repellency and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, low molecular weight fluororesins widely used as lubricants and mold release agents have been produced by various methods. (PTFE) includes a method by telomerization of tetrafluoroethylene (TFE), a method by thermal decomposition of PTFE, and a method by decomposition of PTFE by irradiation of radiation (X-ray, γ-ray).

The above-mentioned conventional method involves various problems such as the use of high temperature and high pressure, and as a result of various studies on a simpler new production method, the present applicant has found that a fluorine-containing resin has a molecular By contacting and reacting with at least one of fluorine, nitrogen trifluoride, halogenated fluoride and rare gas fluoride, a low-molecular-weight fluororesin having a high yield and a controlled molecular weight distribution can be obtained. (JP-B 1-449404).

[0004] Also, low molecular weight products of fluorine-containing resins such as PTFE are excellent in lubricity and non-adhesiveness due to low surface energy, and are used as lubricants, mold release agents, and fluororesin paints. Widely used. Recently, it has been used as an additive to paints and plating for the purpose of water repellency and prevention of snow formation.

However, some conventional fluororesin paints and platings to which low-molecular-weight PTFE is added have high water and oil repellency immediately after coating and plating. At present, there is no material that can be used for practical purposes.
FE resins are desired.

[0006]

The inventors of the present invention have conducted intensive studies on such problems, and as a result, by keeping the fluorine concentration at a specific concentration, a low molecular weight fluorine-containing resin powder having higher water and oil repellency has been obtained. Can be manufactured.

That is, the present invention relates to a fluorine-containing resin powder having a molecular weight of 700 to 4000, which is obtained by cooling a reaction product gas of a molten fluorine-containing resin and a fluorine-based gas, and which is completely fluorinated. A low molecular weight fluorine-containing resin powder having high water / oil repellency which is not wetted by acetone. The fluorine-containing resin is heated to a melting point or higher to 600 ° C. in a reactor to be melted. Contact reaction with at least one of fluorine, nitrogen trifluoride, halogenated fluoride and rare gas fluoride, and the resulting reaction product gas is cooled to 50 ° C. or less by a cooler to deposit a low molecular weight fluorine-containing resin. In the method of collecting particles in a collection container, the ambient temperature is 50 ° C. between the reactor and the collection container.
Until it becomes less than or equal to, the fluorine concentration in the atmosphere gas is reduced to 0.
An object of the present invention is to provide a method for producing a low-molecular-weight fluorine-containing resin powder, which is maintained at 1 vol% or more.

According to the present invention, the fluorine concentration in the atmosphere gas is reduced until the fluorine resin as a raw material is reacted with a molecular fluorine gas or the like to produce a low molecular weight fluorine-containing resin and cool the atmosphere temperature to 50 ° C. or less. When the fluorine concentration is 0.1 vol% or more, a low-molecular-weight fluorine-containing resin having a higher water / oil repellency (molecular weight: 7)
00 to 4000). When the fluorine concentration is 0.1
The volume is not particularly limited as long as it is at least vol%, but is preferably in the range of 0.1 to 20 vol%, and most preferably in the range of 0.1 to 10 vol%, from the viewpoint of economy. If the fluorine concentration is less than 0.1 vol%, fluorination is not completely performed, and a double bond is generated or another atom is bonded.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. FIG.
FIG. 1 is a schematic view of a process for producing a low molecular weight fluororesin powder in the present invention. First, PTFE having a molecular weight of hundreds of thousands to tens of millions was placed in a 2.5 m ³ nickel reactor 1 as a raw material 2.
The chip is charged, for example, at 500 kg, and the temperature is raised to an ambient temperature of 500 ° C. by external heating while supplying a fluorine gas 3 diluted to 5% with nitrogen gas. When held as it is for several tens of hours, gaseous P whose molecular weight has been reduced by the reaction between the surface layer of the molten raw material 2 at the bottom of the reactor and the fluorine gas 3
TFE is produced at a rate of about 500 g / Hr. The gaseous PTFE is taken out of the reactor together with other gas components, here, mainly nitrogen gas, partially unreacted fluorine gas, by-product fluorocarbon gas, and the like. The gas is cooled to 50 ° C. or lower in the provided gas cooler 4. Cooled low molecular weight PTFE is 1-3 μm
Precipitates out of the gas as PTFE particles, and is collected and collected in a collection container such as the bag filter 5.

In this series of reactions, the starting material PTFE
Reacts with fluorine gas to generate low molecular weight PTFE, and keeps the fluorine concentration in the atmosphere gas at 0.1 vol% or more until the atmosphere temperature is reduced to 50 ° C. or less by a cooler or the like. Also, the fluorine concentration in the atmosphere gas can be obtained by analyzing the exhaust gas from the upper part of the bag filter,
It can be arbitrarily controlled by the amount of fluorine gas supplied to the reactor.

The low-molecular-weight fluorine-containing resin powder produced by the method of the present invention has excellent performance as a lubricant and a mold release agent, and has an unprecedented high water and oil repellency. An additive which does not decrease and has excellent performance as a coating or plating additive can be obtained.

[0012]

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.

The method for evaluating the water and oil repellency was as follows. 0.2 g of the low-molecular-weight PTFE particles produced by this production method is placed in a test tube, 100 cc of acetone is added to the test tube, and the mixture is shaken for 30 seconds and allowed to stand for 1 minute, and the wettability to acetone is examined.
The water / oil repellency of the particles was evaluated.

The low-molecular-weight PTFE particles having high water- and oil-repellency do not wet with acetone and thus float and separate on the liquid surface, but the low-molecular-weight PTFE particles having low water- and oil-repellency wet and precipitate with acetone.

The molecular weight of the low molecular weight PTFE produced by this production method was measured by mass spectrometry (M-2500 manufactured by Hitachi), and the molecular weight of the low molecular weight PTFE produced by telomerization used as a comparison Patent No. 3
Relationship between melting point and molecular weight shown in No. 067262, molecular weight = 200 / (685 (1 / melting point (° K) −1/60)
0)).

Example 1 A reaction temperature of 470 ° C. was obtained by the method described in the embodiment of the present invention.
In the above, 30 l / min of 5 vol% fluorine gas was supplied to the reactor to produce a low molecular weight fluorine-containing resin powder. At this time, the water and oil repellency and the molecular weight of the low molecular weight PTFE collected in the bag filter were measured by the above method. The average molecular weight is 3000, and the results of exhaust gas analysis from the upper part of the bag filter at this time are shown in Table 1.

[0017]

[Table 1]

Example 2 The reaction temperature was 470 ° C. according to the method described in the embodiment of the invention.
In the above, 40 l / min of 5 vol% fluorine gas was supplied to the reactor to produce a low molecular weight fluorine-containing resin powder. At this time, the water and oil repellency and the molecular weight of the low molecular weight PTFE collected in the bag filter were measured by the above method. The average molecular weight was 3000, and the results of exhaust gas analysis from the upper part of the bag filter at this time are shown in Table 2.

[0019]

[Table 2]

Comparative Example 1 The reaction temperature was 470 ° C. according to the method described in the embodiment of the invention.
In the above, 10 l / min of 5 vol% fluorine gas was supplied to the reactor to produce a low molecular weight fluorine-containing resin powder. At this time, the water and oil repellency and the molecular weight of the low molecular weight PTFE collected in the bag filter were measured by the above method. The average molecular weight was 3000, and the results of exhaust gas analysis from the upper part of the bag filter at this time are shown in Table 3.

[0021]

[Table 3]

Comparative Example 2 The reaction temperature was 470 ° C. according to the method described in the embodiment of the invention.
In the above, 20 l / min of 5 vol% fluorine gas was supplied to the reactor to produce a low molecular weight fluorine-containing resin powder. At this time, the water and oil repellency and the molecular weight of the low molecular weight PTFE collected in the bag filter were measured by the above method. The average molecular weight was 3000, and the results of exhaust gas analysis from the upper part of the bag filter at this time are shown in Table 4.

[0023]

[Table 4]

Examples 1 and 2, Comparative Examples 1 and 2, and low-molecular-weight PTFE (average molecular weight: 10,000) produced by telomerization were evaluated for water / oil repellency according to the above-mentioned method. Table 5 shows the results.

[0025]

[Table 5]

[0026]

The low-molecular-weight fluorine-containing resin powder produced by the method of the present invention has excellent performance as a lubricant and a mold release agent, and has an unprecedentedly high water and oil repellency. A fluororesin-based paint or plating having a coating film whose oiliness does not decrease can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of a process for producing a low molecular weight fluororesin powder according to the present invention.

[Explanation of symbols]

 1. Reactor 2. Raw material (PTFE) 3. Fluorine gas 4. Gas cooler 5. Bag filter

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mitsuya Ohashi 2805 Imafukunakadai, Kawagoe City, Saitama Prefecture Central Research Laboratory of Glass Co., Ltd. (72) Inventor Hiromi Sugimoto 2805 Imafukunakadai, Kawagoe City, Saitama Prefecture Glass Research Laboratory

Claims (2)

[Claims] 1. A fluorine-containing resin powder having a molecular weight of 700 to 4000, which is obtained by cooling a reaction product gas of a molten fluorine-containing resin and a fluorine-based gas, and which is completely fluorinated and wetted with acetone. Low molecular weight fluorine-containing resin powder with high water and oil repellency. 2. The method according to claim 1, wherein the fluorine-containing resin is heated to a melting point of not lower than 60
A reaction product gas generated by heating and melting at 0 ° C. and causing a contact reaction with at least one of molecular fluorine, nitrogen trifluoride, halogenated fluoride and rare gas fluoride at an ambient temperature of 200 to 550 ° C. Is cooled in a cooler to 50 ° C. or less, and the precipitated low molecular weight fluorine-containing resin particles are collected in a collection vessel, and the atmosphere is kept at 50 ° C. or less between the reactor and the collection vessel. 2. The method according to claim 1, wherein the fluorine concentration in the gas is maintained at 0.1 vol% or more.