JPH011711A - Modified polytetrafluoroethylene fine powder and method for producing the same - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to paste extrudability, rolling workability, stretching workability, and sintering properties of molded products thereof, dimensional stability after sintering, adhesion, transparency, and mechanical properties. The present invention relates to a modified polytetrafluoroethylene (hereinafter referred to as PTFE) fine powder that has excellent properties such as fine powder, and a method for producing the same.

[Conventional technology]

After adding a liquid lubricant to the PTFE fine powder and extruding it as a paste, it can be used as a sealing material as it is or in the unfired state after being rolled into a sheet, or it can be fired and made into sheets, pipes, rods, etc. Used as molded products.

It has also been found that if the unfired product after paste extrusion is stretched as it is or after being rolled into a sheet, only the porosity decreases without substantially decreasing the cross-sectional area, resulting in a porous body. This stretched porous material is used as a sealing material in its unfired state, and is then fired to form a tough P.
It is used as a TFE continuous porous sheet for various purposes.

Because PTFE fine powder is used for such special molding methods and applications, it is first required to have high productivity in paste extrusion molding, rolling and stretching processability, and also dimensional stability during firing and post-calcination properties. However, it is also known that all of these required properties are largely controlled by the PTFE fine powder itself used as a raw material. However, these required properties range widely from various moldability to the properties of the final molded product.
Looking at the known PTFE fine powders that have been developed so far, for example, they have excellent moldability but poor mechanical properties, and even if only moldability is considered, paste extrudability is good but it is difficult to stretch. It is common for certain characteristics to be improved at the expense of other characteristics, such as saying that sex is bad.

For example, tetrafluoroethylene (hereinafter referred to as TFE)
A method is known in which PTFE is modified by copolymerizing it with another fluorine-containing monomer in an amount less than about 1% by weight, while maintaining the inherent non-melt processability of PTFE (Japanese Patent Publication No. 37-1989). No. 4643, Special Publication No. 56-26
242 and Japanese Patent Publication No. 50-38159), the copolymers obtained in this way are particularly called modified PTFE, and are distinguished from melt-mouldable TFE copolymers. Aperture ratio (HRR1 aperture ratio (R
R): Ratio of the cross-sectional area of the part of the cylinder filled with paste of the extruder in paste extrusion and the exit part of the extrusion die)
Extrudability, firing performance (especially firing speed), transparency of molded products, etc.
Although it is more or less improved compared to the FE homopolymer, the rollability (easiness to obtain a wide and thin sheet when rolling a paste extrudate to obtain a sheet) and stretchability are reduced. It is also known that PTFH with excellent stretchability can be obtained by solidifying a homopolymer of TFH and giving it special SC melting properties (Japanese Patent Publication No. 56
54016 and Japanese Patent Publication No. 58-39443), these high molecular weight PTFEs are inferior in paste extrudability at high drawing ratios, and are

This results in poor productivity, poor sinterability of molded products, and poor self-adhesiveness and transparency of the fired products.

[Problem that the invention seeks to solve]

The object of the present invention is to produce a modified P that has good paste extrudability and high rolling workability and stretching workability.
An object of the present invention is to provide a TFE fine powder and a method for producing the same.

Another object of the present invention is to use a new modified PTFE fine material that has excellent dimensional stability during firing of paste extrusion molded products, especially tube molded products, and that molded products after firing have excellent mechanical properties, transparency, etc. An object of the present invention is to provide a powder and a method for producing the same.

Still another object of the present invention is to provide a PTFE fine powder that has excellent sinterability and adhesion properties for drawn products.

[Means for solving problems]

As a result of research into legalization, it has been found that the above-mentioned problems of the prior art can be solved by the modified PTFE fine powder of the present invention and the method for producing the same.

The modified PTFE fine Baugu of the present invention has tetrafluoroethylene and the general formula, X (CFz), IOCF =
CF t (wherein, X represents a hydrogen, fluorine or chlorine atom, and n represents an integer of 1 to 6) and C1Ft (OCFz
CFzCFz)-(OCF(CFz)CFz)tOcF
=CF! Substantially from a copolymer with at least one olefin selected from the fluoroalkyl vinyl ethers shown in become,
The content of the olefin is 0.02 to 0.3% by weight, preferably 0.03 to 0.2, and the number average particle size is 0.05 to 0.
．． It is an aggregate of colloidal particles of 6 μm, and the specific melt viscosity of the copolymer at 380° C. is 6.0XlO” to 3
0x10I0 boise, preferably 8.0x1010~2
5 x 101° poise, standard specific gravity 2.135~2
．． 175, particularly 2.140 to 2.160, and is characterized by a green elongation of the paste extrudate of 500% or more.

The modified PTFE fine powder of the present invention requires the use of the above-mentioned fluoroalkyl vinyl ether as a main component as a modifier, and other known modifiers,
For example, the effects of the present invention cannot be obtained by using hexafluoropropene or chlorotrifluoroethylene. If the content is too low, the adhesiveness and transparency of the fired molded product will be poor, and if it is too high, the molded product will be too soft. Become. If the specific melt viscosity of the polymer is too low, the rollability and stretchability of the paste-processed molded product will be poor, and it will be difficult to extrude and fire a thick pipe. 8. Molded products become significantly deformed due to melt flow.

That is, the dimensional stability during firing is poor. Conversely, if the specific melt viscosity is too high, extrudability under high drawing ratios (HRR) may be adversely affected.

The first feature of the polymer of the present invention is that it has a higher melt viscosity and a lower standard specific gravity than conventional modified PTFE fine powders. is related to the mechanical properties of the fired product, and can be considered to be a requirement for excellent practical properties.Conversely, low melt viscosity and low standard specific gravity improve rollability and stretchability. inferior to, SSC is 2.175
For larger ones, mechanical properties (e.g. bending resistance)
It was found that the polymer of the present invention has a melt viscosity of 6XlO+a voids or more and a standard specific gravity of 2.17.
5 or less, the green elongation (measured as the elongation when pulling the unfired molded product after paste extrusion molding of fine powder and removal of the lubricant) is 500% or more, and if it has these characteristics, the polymer The molded product obtained from this process is extremely strong, with a bending life of over 6 million times.)
.

The degree of green elongation can be used as a guideline for the rolling and stretching processability of paste-processed products, but if the degree of green elongation is less than 500%, a wide width cannot be obtained in rolling and the film thickness may be thin. First, the pores tend to become uneven or break during stretching.As mentioned above, the fine powder of the present invention has a high degree of green elongation and has excellent rolling and stretching processability.

It is believed that the polymers of the present invention are of very high molecular weight in nature. It can be understood that the good mechanical properties (eg flex resistance) result from the high molecular weight of such polymers. Furthermore, the reason why the polymer of the present invention has excellent rollability and stretchability even though it is a modified system is because the specific properties and high molecular weight of fluoroalkyl vinyl ether modification are unknown. It is thought that they are related.

The above-mentioned PTFE fine powder using fluoroalkyl vinyl ether as a modifier
No. 4643 (a) and Special Publication No. 50-38159 (b)
In the specification, fluoroalkyl vinyl ether modified C
sF? It has been implemented for OCF-CF t (PPVE). Of these, in the latter (b), the former (
The standard specific gravity and melt viscosity of Examples 27 and 28 in b) are 2.223 and 6.2 x 1010 poise, and 2.184 and 4.8 x 1010 poise, respectively, and the PPVE content of Example 28 is 0. found a method for producing fluoroalkyl vinyl ether-modified PTFH with a low standard specific gravity and low melt viscosity compared to .114% by weight;
Furthermore, it is stated that this polymer has excellent R mechanical properties. Furthermore, FVE-modified r'TF, E with a low standard specific gravity and low melt viscosity cannot be obtained with the polymerization initiator di-succinic peroxide used in the former (a) known example, and persulfate specifically improves its physical properties. It states that it gives a polymer with

In contrast, the present invention has discovered that a fluoroalkyl vinyl ether-modified PTFE fine powder having a high melt viscosity while having a low standard specific gravity that does not belong to any of the above-mentioned known examples can be obtained by a specific manufacturing method,
Surprisingly, this polymer has mechanical properties equivalent to or better than the latter (b) known example polymer, and moreover, the modified P
It was discovered that TFE fine powder also has excellent rollability and stretchability, which were previously considered to be inferior.

The above-mentioned modified polytetrafluoroethylene of the present invention is produced by converting tetrafluoroethylene into a general formula, X (C
F*) 110CF''CF* (wherein, X represents a hydrogen, chlorine or fluorine atom, and n represents an integer of 1 to 6) and C5Ft (OCFzCFzCFx).

(OCF (CF3)CFff) LOCF-CFf
(In the formula, 1 and I are integers of 0 to 4, however, fog and 1 are not 0 at the same time) together with at least one fluoroalkyl vinyl ether at a reaction pressure of 6 to 40 kg/aJ, Temperature 10-95℃
In copolymerizing, after the start of polymerization, at least 10% by weight, especially 30% by weight or more of the final polymer produced, and before 85% by weight, especially 70% by weight, is polymerized, (a) the polymerization system (b) by adding an underwater radical scavenger in an amount of 0.2 to 5 times the number of moles of the polymerization initiator used, or (b) by lowering the temperature of the polymerization system by 10 to 40 °C. It can be produced by changing the polymerization conditions.

The manufacturing method of the present invention uses a polymerization initiator in the presence of a fluorine-containing dispersant in accordance with the conventional method for manufacturing PTFE fine powder, except that the polymerization conditions are changed during the polymerization as described above. It is carried out in an aqueous medium under stirring.

The underwater radical scavenger added to the polymerization system is relatively soluble in the aqueous medium, and selectively adds or attaches to low-molecular radicals in the dispersion medium rather than to the surface of the polymer latex particles in the reaction system. Any compound can be used without particular limitation as long as it has a polymerization termination ability that hardly gives reinitiation ability after chain transfer. For example, 25
Aromatic hydroxy compounds, aromatic amine compounds, and quinone compounds having a solubility in water of 2.5 x 10-'' mol/l or more at °C can be used, but specifically hydroquinone, catechol, pyrogallol, p-phenylene, etc. Diamine, p-benzoquinone, N2N-diethylhydroxylamine, etc. can be preferably used.

As the polymerization initiator, persulfates such as ammonium persulfate and potassium persulfate, water-soluble organic peroxides such as disuccinic acid peroxide and diglylic acid peroxide, or mixtures thereof are used. In the case of persulfates, the amount used is from 2 to 300 ppm, preferably from 2 to 200 ppm, based on the aqueous medium. In the case of disuccinic acid peroxide, the amount is 20 to 10 DOppm, preferably 40 to 300 ppm, based on the aqueous medium. It is preferable to use disatane peroxide and persulfate in combination to improve the paste extrudability of the resulting PTFE fine powder, and in this case, the weight ratio of both is 50/] ~
It is most preferable to use a range of 8/l. Both initiators may be charged into the reaction system at the same time, but the timing of charging may be staggered. When the reaction is carried out at a low temperature, a reducing agent such as sodium sulfite or acidic sodium sulfite may be added to the peroxide to form a redox system.

Examples of water-soluble fluorine-containing dispersants include general formulas, X(
CF, C0OH (wherein, X is H, F, or C1 atom,
a is an integer from 6 to 12), CI (CFt CF CI )
b CF t COOH (in the formula, b is an integer from 2 to 6)
, (CF5)tcF(CF2CF2)cCoOH (in the formula, C is an integer of 2 to 6), F(CFZ)d○(CF
(Y)CFz O), CF (Y)COOH (in the formula, Y
is F or CF, d is an integer of 1 to 5, and e is an integer of 1 to 5), and their ammonium salts or alkali metal salts (e.g., potassium salts, sodium salts), etc. are used. But especially - Ritual C,,F2. ．． -1coox or 03F70(CF(C
F,)CF20)ICFCCF,)COOX (wherein,
It is preferable to use a compound in which n is an integer of 6 to 9.1 and X is an ammonium group and represents an alkali metal. As for the method of charging the reaction system, the entire amount may be charged into the reaction system in bulk before the reaction, but programming charging as described in Japanese Patent Publication No. 44-14466 may also be carried out. The amount used is 0.03 to 0.3% by weight, preferably 0.05 to 0.3% by weight, based on the aqueous medium used in the reaction.
It is 2% by weight. It is most preferable to charge the necessary amount of the fluoroalkyl vinyl ether, which is a modifier used in the present invention, into the reaction system at once at the start of the reaction.

For example, a hydrocarbon having a carbon number of 12 or more that is liquid under the reaction conditions may be added to the aqueous medium as a dispersion stabilizer that is substantially inert to the reaction. In addition, pHfc during the reaction
! For example, ammonium carbonate, ammonium phosphate, etc. may be added as a buffer to adjust the temperature.

+n The degree of polymerization can be selected within a wide range of 10 to 95°C.

However, when a persulfate or a water-soluble peroxide as a polymerization initiator is used alone or in combination, a temperature of 60 to 90°C is appropriate. When the initiator is a redox system such as persulfate and sodium sulfite, or disuccinic acid peroxide and reduced iron, a lower temperature range can be selected.

In order to obtain the modified PTFE fine powder of the present invention, it is necessary to lower the temperature of the reaction system during the polymerization unless the polymerization conditions are changed by adding an underwater radical scavenger. The temperature range to lower is 10 to 40
It may be selected within the range of °C. There is no problem in using the addition of an underwater radical scavenger and lowering the reaction temperature in combination, and in this case, the width of the temperature drop can be made smaller.

By changing the above polymerization conditions in the production method of the present invention, the reaction time becomes at least 1.3 times longer, usually at least twice as long, as compared to the case where no change is made.

This is because it suppresses the increase in the total number of radicals during the reaction, and as a result, a high molecular weight polymer is produced.

The underwater radical scavenger should be added in a small amount (20 mol % or more and 500 mol % or less of the amount of the added initiator, preferably 50 mol % to 300 mol %). If it is added in large quantities, not only will the productivity drop significantly, but the molded product will be colored, which is unfavorable in terms of quality.

Furthermore, in reactions using disuccinic acid peroxide as a polymerization initiator, it is particularly recommended to increase the molecular weight by lowering the reaction temperature rather than by adding an underwater radical scavenger. This is because certain underwater radical scavengers increase the total number of radicals through a redox reaction with disuccinic acid peroxide.

Polymerization is usually carried out by gas pressurization of TFE itself.
The reaction is allowed to proceed while maintaining the pressure in the range of kg/ci. In addition, when a persulfate is used as a polymerization initiator, the most suitable polymerization pressure is in the range of 6 to 17 +r/cal. This is because the reaction rate is too high in high-pressure reactions, and the reaction ends before the effect of changing the polymerization conditions mid-way is fully exerted.Normally, the pressure is kept constant during the reaction, but As shown in Japanese Patent No. 60-76516, it is also possible to add an operation to control the particle size of the obtained polymer by varying the TFE pressure during the process. Particularly preferable conditions for the production method of the present invention are as follows.

(2) When 2 to 30 ppm of ammonium or alkali metal salt of persulfate is used as a reaction initiator and the reaction is carried out at a pressure of 6 to 17 kg/cd.

(2) As a reaction initiator, 20 to 11,000 pp of disuccinic acid peroxide and 1,150 to 1/8 times the amount of ammonium persulfate are used together, and the polymerization conditions are changed according to the method (b).

case.

■General Ni Ca7m as a water-soluble fluorine-containing dispersant. .

coox or C3F 7o (CF (CF x) C
F20)1cF(CFzCOOX (where n is 6 to
9, I is an integer of 1-2, X represents an ammonium group or an alkali metal) at a concentration of 0.05 to 0.2% by weight, and ammonium persulfate or an alkali metal salt as a reaction initiator at a concentration of 5 to 20 ppm K. When used and reacted at a temperature of about 60-90°C.

(2) When 40 to 300 ppm of disuccinic acid peroxide and ammonium persulfate of 1150 to 1/8 times the amount and 3 to 10 ppm K degree are used together as a reaction initiator.

The reaction is terminated by releasing the monomer from the system and stopping stirring when the polymer concentration reaches 20 to 45% by weight. The aqueous dispersion of polymer (referred to as polymer latex or simply latex) is then removed from the autoclave and transferred to the next step, namely coagulation and drying. After diluting to the desired polymer concentration and adjusting the pH to neutral or alkaline as the case may be, the mixture is stirred more vigorously than during the reaction in a container equipped with a stirrer. At this time, stirring may be performed while adding water-soluble organic compounds such as methanol and acetone, inorganic salts such as potassium nitrate and ammonium carbonate, and aeII-free compounds such as hydrochloric acid, sulfuric acid, and nitric acid as coagulants.

In addition, by adding pigments for coloring and various fillers to improve mechanical properties before or during coagulation, it is possible to obtain a PTFE fine powder containing fillers in which these fillers are uniformly mixed. Can be done. In addition, if appropriate stirring is performed, the polymer separates from the latex during coagulation, and then granulation and sizing can be performed simultaneously, improving the handling of the powder after coagulation.

Drying is usually performed by keeping the wet powder obtained by coagulation in a state where it is not very fluid, preferably in a state of stillness, and using means such as vacuum, high frequency, hot air, etc., and contact of the powders with each other, especially at high temperatures. Generally, emulsion polymerization type PT is used for friction.
It has an unfavorable effect on FH. This is the type of P
This is because TFE particles have the property of easily becoming fibrillated even under a small shearing force and losing their original crystalline structure after completion of polymerization. The drying temperature is 10 to 250°C, preferably 100 to 200°C, but the drying temperature has a considerable influence on paste extrusion, as the higher the drying temperature, the higher the Pace I extrusion pressure. therefore,
When comparing the paste extrudability of the resulting powders, it is at least necessary that drying be carried out at the same temperature.

In addition to the use as a fine powder, the polymer of the present invention can also be used in applications starting from latex. For example, a nonionic surfactant is added to the latex after the reaction to stabilize and further concentrate, and in some cases, an organic or inorganic filler is added to form a paint. When the paint is coated on a metal or ceramic surface, a surface with excellent gloss, smoothness, and wear resistance can be obtained, and is suitable for coating rolls, cooking utensils, etc., and impregnating glass cloth.

The methods of analysis and testing of polymer latex and PTFE fine powder in this specification are as follows.

Polymer concentration: 10g of polymer latex was collected on the
Leave the stalks in a drying oven at 50°C for about 3 hours to dry them. Weigh the solid content and use this as the polymer concentration.

Number average particle diameter: Determined by measuring the transmittance of 550 nm projected light per unit length of polymer latex diluted with water to a solid content of 0.22niff1% and the diameter in a certain direction in a transmission electron micrograph. It is determined from the above transmittance based on a calibration curve with the length average particle diameter.

Standard Specific Gravity (SSG): Determined by the ratio of the weight in air of a sample made by standard methods to 1iffi of the same volume of water (23°C). When making a standard sample, 12g sample of dry polymer powder
Place it flat between aluminum foil in a cylindrical mold with a diameter of 2.86 mm, and apply pressure for about 30 seconds to a final pressure of about 35 mm.
2 kg/cj and keeping this pressure for 2 minutes, the resulting preform is placed in an air oven at 290°C and after increasing the temperature of this oven from 290°C to 380°C at a rate of 2°C/min. It was held at 380°C for 30 minutes, then cooled to 294°C at a rate of 1°C for 1 minute, then taken out of the oven and left to stand at 23°C for 3 hours.

Normally, SSG is considered to be an indirect means of expressing the number average molecular weight of tetrafluoroethylene polymers that do not contain modifiers.
-11u, the lower the SSG, the higher the molecular weight. However, it is fundamentally incorrect to estimate the molecular weight of modified polytetrafluoroethylene using SSG as in the present invention.

Paste extrusion test: +11 At a reduction ratio (RR) of 100, 50 g of fine powder and an extrusion aid (trade name rlP1), which is a hydrocarbon oil.
620, manufactured by Idemitsu Petrochemical Co., Ltd.) in a glass bottle and aged for 1 hour at room temperature (25±2°C). Next, the above mixture was filled into an extrusion die (having an orifice with an inner diameter of 2.54 mW and a land length of 7 mm at the lower end with a constriction angle of 30 degrees) equipped with a cylinder (inner diameter of 25.4 mm).
A load of kg is applied to the piston inserted into the cylinder and held for 1 minute.

Immediately thereafter, the above mixture is extruded indoors at a ram speed (pressing down speed) of 208 m/min to obtain a lofted product. The extrusion pressure (kg/d) is defined as the value obtained by dividing the pressure at the part where the pressure reaches an equilibrium state in the latter half of extrusion by the Norinder cross-sectional area.

In the case of f21RR710, in the paste extrusion procedure of RRloo, the aperture angle is 30
degree, orifice diameter 0.95 ***, land length 2.
The process is carried out in the same manner except that an extrusion die of Q*m is attached. In this case, not only the extrusion pressure but also the appearance of the extruded product is observed and evaluated based on the following criteria.

A: There is no meandering during paste extrusion, and the extrudate surface is smooth.

B: Slight meandering, but the extrudate surface is smooth.

C: Meandering, with a small number of protrusions on the surface of the extrudate (this can be improved by changing the extrusion speed and amount of auxiliary agent).

D: Severely meandering, with many protrusions on the extrudate surface. Or cut it during extrusion. Poor practicality.

Elongation of unfired beads (also called green elongation): Dry the loft-shaped extrudate obtained by paste extrusion of RRloo at about 100°C for about 10 hours, and elongate it from the latter half where the extrusion pressure is stable to about 7 marks. Cut out 5 samples of length. Approximately 151 mm on each end of each sample is fired in a salt bath at 380° C., and scales are marked in the center at intervals of 20.1 mm along the length of the surface. Next, grasp both ends of the sample with the clamps of the tensile tester, pull the sample at a constant speed of 200 m1/min, read the length between the scales at break (EL), and calculate the elongation (%) using the formula below. demand.

20 (Regarding) The number of tests is 5 times, and the elongation (%) is calculated by averaging the values of 3 times excluding the maximum and minimum values.

Furthermore, during the tensile test, the room temperature is controlled at 24±0.5.

Specific melt viscosity: Thermoflex sample lower i T M A J (
A creep test is performed and measured using a Rigaku TLIa (manufactured by Rigaku TLIa Co., Ltd.) according to the following procedure.

First, a sample is prepared by the following method. A cylindrical mold with an inner diameter of 50 mm was filled with 80 g of powder sandwiched between pieces of paper.
The final pressure is approximately 352 kg/c+J by applying pressure to each body per second.
Then, the molded body was removed from the mold and fired for 90 minutes in an air electric furnace heated to 371°C, and then heated to 250°C at a rate of 1°C/min. The temperature was lowered, kept at this temperature for 30 minutes, and then taken out.

This cylindrical fired body is cut along the side, and the thickness is 0.
．． Obtain a belt-like sheet of 5 cranes.

A small piece with a width of 4N to 5fi and a length of 15M is cut from this sheet, the width and thickness are accurately measured, and the cross-sectional area is calculated. Attach the sample mounting brackets to both ends of the small piece so that the distance between them is 1.0 a.
Install it so that it is m.

This fitting-sample assembly was placed in a cylindrical furnace, and
The temperature is raised from room temperature to 380°C at a rate of 0°C/min and this temperature is maintained. After holding for about 5 minutes, a load of about 15 g is applied. From the elongation time change curve, the elongation between 60 and 120 minutes after loading is read and the ratio to time (60 minutes) is determined. The specific melt viscosity is calculated from the following relational expression.

3 X (d Ly/ d T) X AtHowever, η
- Specific melt viscosity (voids) W - Tensile load (g) Lt - Length of the sample (380°C> (am) g - Constant of gravity 980 cm/sec 2 dLT/dT - Time of elongation between 60 and 120 minutes (C117 seconds) A7- Cross-sectional area of sample (380° C.) (C+a) Here, Lv/At can be calculated from the separately determined thermal expansion measurement using the following formula.

LT/At = '0.80 x L (length at room temperature)/A (cross-sectional area at room temperature) Stretch test: A tensile testing machine with a circulating air oven is used. R
The rod-shaped extrudate obtained by Rloo's paste extrusion is cut, clamped at both ends leaving a distance L (am) between the clamps according to the stretching conditions 1 to 4 in the table below, and heated to T°C. Then, it is stretched at a stretching speed E (am/min) until the stretching ratio K is reached.

The stretched rod is evaluated for uniformity of stretching and smoothness of appearance of the stretched product.

First, the uniformity of stretching is determined from the formula below by placing an ink mark in the center of the rod between the clamps before stretching and measuring the deviation after stretching.

Next, the appearance of the stretched product is evaluated according to the following criteria.

A Smooth B Slightly uneven C Very uneven D Bending life (flax 1ife) broken during stretching: MIT test machine described in ASTM D2176-637 is used. The number of double bends required to break the sample while applying a tension of 1.2 kg is recorded. However, the sample used was a sheet of 0.50 nm obtained when measuring the specific melt viscosity, cut into a width of 6.5 mm and a length of 14 mm.

With the exception of Example 4, those with a bending life of 6 million times or more were not further tested.

Adhesive test samples are used by cutting six pieces of the 0.50 dragon sheet obtained in the measurement of specific melt viscosity into lengths of about 10 eIa.

Two sheets of 3&fl are stacked one on top of the other and sandwiched between two 2-++ thick aluminum plates so that only the ICs in each set of sheets are in contact with each other. This situation! Place in a heat press set at 0°C, and pressurize to 70 kg/e+d after 5 minutes. After 5 minutes of pressurization, cool with water and remove the sample. Before measurement, the width of the sample was cut to 10.0 as, 50 mm.
/ minute tensile test,! 11 Separation strength kg/cm
seek. The adhesiveness of the polymer of the present invention is extremely excellent, and in all experimental examples except Comparative Example 2, the sheet itself was broken without peeling.

Transparency: Can be determined qualitatively or quantitatively using the 0.50 dragon sheet obtained when measuring specific melt viscosity. All experiments other than Comparative Example 2 showed high transparency.

Example 1 A stainless steel (SUS31
6) Add 540 mjlSm of deionized water to the manufactured autoclave.
, p, solid paraffin wax at 56°C 30. After charging 0.55 g of ammonium perfluorooctanoate and purging the system three times with nitrogen gas and twice with TFE gas while heating it to 70°C to remove oxygen, the internal pressure was reduced to 25.5 g with TFE gas. 5kg/cdc: 31J stirring at 500r
pm, and keep the internal temperature at 70°C.

Next, perfluoropropyl vinyl ether (PpvE)
1.5 g, then an aqueous solution of 9.4 μm of ammonium persulfate (APS) dissolved in 5 mff of water was compressed with TFE, and the internal pressure of the autoclave was increased to 26 kg/ciG. The reaction proceeds at an accelerated rate, but the reaction Temperature: 70℃, stirring: 5
Try to keep it at 00 rpm. TFE is continuously supplied to keep the internal pressure of the autoclave at 26±0.5 kg/colG.

The TFE consumed in the reaction after adding the initiator is 120
When g is reached, 5 ml! An aqueous solution of 4.7 μm of hydroquinone dissolved in 100 μm of water was injected using TFE.

The reaction started when 237 g of TFE monomer was consumed.
Stirring and monomer supply were stopped, and the gas in the autoclave was immediately released to normal pressure to complete the process. The timing of adding hydroquinone is 51 days from the above data (120/237X
100), the total reaction time was 4.4 hours, and the number average particle size was 0.19 μm.

A part of the obtained latex was dried to dryness and the solid content was calculated as a polymer concentration of 30.1 mff1%.

After rusting and washing, the obtained latex was heated at 140°C for 16
Dry for an hour. After drying, the PPVE content in the polymer was measured using the obtained fine powder and found to be 0.06.
It was 1% by weight. In addition, the content of PPVE in the polymer was determined as the value obtained by multiplying the ratio of the absorbance at 995 cm-' and the absorbance at 2360 cm-' by 0.95 in the infrared absorption spectrum hand as the weight percent in the polymer. It is something.

Further, the SSG of the polymer was 2.156.

Furthermore, the specific melt viscosity of the obtained fine powder −ε When the power was measured, it was found to be 1.2×10 10 voids.

Further, when paste extrusion was performed using RRloo, the extrusion pressure at equilibrium was 123 kHz/cut, and the green elongation (elongation of unfired beads) of the obtained bar was 1100% when θ゛1 was determined.

RI? The extrusion pressure at 700 was 772 kg/ci, and the appearance of the extrudate was B. As shown in Table 1, the stretching processability is extremely high compared to that of Comparative Example 1, which has a low specific melt viscosity. In the adhesion test, the sheet itself broke without peeling. The transparency of the fired product was also outstanding. The MIT test results were over 6 million times.

The following examples and comparative examples are summarized in Table 1.

Example 2 545 mf of deionized water was added to the same autoclave as in Example 1.
f, 30 g of reagent-grade liquid paraffin and 0.55 g of ammonium perfluorooctanoate were charged, and the system was purged three times with nitrogen gas and twice with TFE gas while heating to 70°C to remove oxygen. , ;2- T F E waste T: Internal pressure 'c 25.5 kg/cIa
Turn to G and start stirring at 500 rpm, keeping the internal temperature at 80°C.

Next, ppVEl, 4a, and then a solution of 9.9 μm of ammonium persulfate dissolved in 5 ml of water were pressurized with TFE gas to bring the internal pressure of the autoclave to 26 kg/cotG.

The reaction progresses at an accelerated rate, but stirring is kept at 50 rpm during the reaction.
Keep the autoclave internal pressure constant at 26±Q, 5
TFE is continuously supplied into the system to keep it at kg/cdG. However, the reaction temperature, which was maintained at 80°C from the beginning of the reaction, was approximately 0.7°C/0.7°C from the time when 80g of TFE was consumed.
After 103 g of TFE has been consumed, the temperature is maintained at 50°C.

When 271 g of TFE monomer was consumed, stirring and monomer supply were stopped, and the gas in the autoclave was immediately discharged to normal pressure to terminate the reaction.

Total reaction time was 3.9 hours. The obtained latex was treated in the same manner as in Example 1 to obtain fine powder.

・Example 3 A stainless steel (SUS316) autoclave equipped with an anchor-type stirring blade and a jacket for temperature control, and containing 8 volumes of 61 stainless steel (SUS316) was filled with 2960 mj of deionized water! , m, p, 56℃
120 g of solid paraffin wax and 3.0 g of ammonium perfluorooctanoate were charged, and while heating to 70°C, the system was purged three times with nitrogen gas and twice with TFE gas to remove oxygen, and then replaced with TFE gas. Internal pressure 7.0kg/
Stir at 250 rpm and keep the indoor bath at 70°C.

Then PPVEo, 5g followed by 2Q m 1. 1 in water
Pressure-inject an aqueous solution containing ammonium persulfate (5) using TFE and bring the internal pressure of the autoclave to 8.0 kg/jG.The reaction proceeds at an accelerated rate, but the reaction temperature should be kept at 70°C and the stirring at 250'rpm. do.

TFE always maintains the internal pressure of the autoclave at 8.0 kg/c.
Continuously supply to maintain dG.

The TFE consumed in the reaction after adding the initiator was 484
g, the 0 reaction in which an aqueous solution of 7.5 μ of hydroquinone dissolved in 29 ml of water is injected using TFE is 1102
When g of TFE monomer was consumed, stirring and monomer supply were stopped, and the gas in the autoclave was immediately released to normal pressure to complete the autoclave. The timing of hydroquinone addition was 44% (484/l 102 x 100) from the above data, and the total reaction time was 23.2 hours. The obtained latex was coagulated, washed, and then dried at 200°C for 16 hours. The PPVE content in the polymer was 0.03% by weight.

Example 4 2960 m of deionized water was placed in the same autoclave as in Example 3.
j! , 100 g of reagent-grade liquid paraffin and 3.0 g of ammonium perfluorooctanoate were charged, and the system was purged three times with nitrogen gas and twice with TFE gas while heating to 70°C to remove oxygen. Increase internal pressure to 7.0kg with gas
/c+JG and stir at 250 rpm to bring the internal temperature to 70°C.
Keep it.

Next, 2.2 g of PPVE followed by 22.5 g in 10 mJ of water.
30 ml of an aqueous solution containing ammonium persulfate (2) and 375 g of disuccinic acid peroxide (DSAP) are pressurized into the inlet with TFE gas, and the internal pressure of the autoclave is set to 8.0 kg/cslG. The reaction proceeds at an accelerated rate. , Stirring was kept constant at 250 rpm during the reaction, and the internal pressure of the autoclave was always 8.0 ± 0.2 kg/cdG.
TFE is continuously supplied into the system to maintain the temperature. However, the reaction temperature maintained at 70°C from the beginning of the reaction was
from the time when 680g of TFE was consumed, at a rate of approximately 0.4°C/min, and from the time when 790g of TFE was consumed, the temperature decreased by 50°C.
Keep it at ℃.

When 1,620 g of TFE monomer was consumed, stirring and monomer supply were stopped, and the gas in the autoclave was immediately discharged to normal pressure to terminate the reaction.

Total reaction time was 29.4 hours. The obtained latex was treated in the same manner as in Example 1 to obtain fine powder.

The external appearance of the extrudate in the RR710 extrusion was A, which was the best among the Examples.

Example 5 545 ml of deionized water was placed in a glass autoclave (manufactured by Pressure Glass Industry Co., Ltd.) with an internal capacity of 11 and equipped with a temperature-adjustable stainless steel anchor-type stirring blade. Reagent-grade liquid paraffin 30. and 0.55 g of ammonium perfluorooctanoate, and while heating to 70°C, purged the system with nitrogen gas three times and twice with TFE gas to remove oxygen, and then lowered the internal pressure to 7.5 g with TFE gas. 0 k+r/c
a G, stir at 500 rpm, and maintain the internal temperature at 70°C.

Next is PPVEo, 8g! It’s 5m7! 8.2■ in water
A solution containing dissolved ammonium persulfate is injected with TFE gas, and the internal pressure of the autoclave is set to 8.0 kg/crAG.The reaction proceeds at an accelerated rate, but stirring is carried out at 50 Org during the reaction.
The pm is kept constant and the internal pressure of the autoclave is always 8.0±.
TFE is continuously supplied to maintain the concentration at 0.2 kg/cdG. However, the reaction temperature, which was maintained at 70°C from the beginning of the reaction, was approximately 1.0°C/1.0°C from the time when 110g of TFE was consumed.
After 140 g of TFE has been consumed, the temperature is maintained at 50°C.

When 264 g of TFE monomer was consumed, stirring and monomer supply were stopped, and the gas in the O-1-crepe was immediately discharged to normal pressure to terminate the reaction.

Total reaction time was 8.5 hours. The obtained latex stain was treated in the same manner as in Example 1 to obtain a fine powder.

Example 6 In Example 5, Cz F tO was used instead of PPVE.
CF (CF) x CF z = CF 2 as 4.
8 g was charged and the reaction was carried out using the same amount of ammonium persulfate as an initiator. The stirring speed and the internal pressure of the autoclave were also the same as in Example 5. However, the reaction temperature is 12
It is kept at 70℃ until 0g is consumed, and after that it is kept at about 1
．． The temperature is decreased at a rate of 0°C/min, and the temperature is maintained at 45°C after 138g of TFE is consumed.

The reaction is stopped when 269 g of TFE monomer has been consumed.

Total reaction time was 9.1 hours. The obtained latex was treated in the same manner as in Example 1 to obtain fine powder.

The content of the modifier was measured in the same manner as in Example 1.

Comparative Example 1 The following experiment was carried out according to the method described in Japanese Patent Publication No. 50-38169.

In Example 1, APS preparation ■ was changed to 13■,
The reaction is carried out in the same manner, except that no hydroquinone is added, and is terminated when 263 g of TFE monomer is consumed.

Total reaction time was 1.85 hours. The obtained latex was treated in the same manner as in Example 1 to obtain fine powder.

The green elongation (elongation of unfired beads) of the extrudate is as small as 340%, and the drawing property is also poor.

Comparative Example 2 The following reaction was carried out according to the method described in Japanese Patent Publication No. 50-39943.

In the same autoclave as in Example 3, add 2960 ml of deionized water.
mj! , m, p, 120 g of solid Halafinwa J Tx at 56°C and 3.0 g of ammonium perfluorooctanoate were charged, and heated to 70°C with nitrogen gas for 30 minutes.
After replacing the system twice with TFE gas to remove oxygen,
Adjust the internal pressure to 7.0 kg/cnlG with TFE gas and keep one stomach at 70'C at 250 rpm.

Next, follow with 15 g of ammonium persulfate in 20 mf of water? The poured water was compressed with TFE gas to bring the internal pressure of the autoclave to 8.0 kg/cjG.

The reaction progresses slowly but at an accelerated rate, but the reaction temperature is 7.
Maintain the temperature at 0°C and the stirring at 25 rpm. TFE is continuously supplied into the system so that the internal pressure of the autoclave is always maintained at 8.0 kg/c+dG.

The TFE consumed in the reaction after adding the initiator is 570
g (4.8 hours after APS addition), 20 ml
An aqueous solution containing 7.5 ml of hydroquinone in 1 ml of water is injected using TFE.

Although the reaction rate decreases considerably, the reaction continues, and when a total of 1270 g of TFE 7-mer is consumed, stirring and 7-mer supply are stopped, and the gas in the autoclave is immediately released to normal pressure to terminate the reaction. Ta. The timing of hydroquinone addition is 45% according to the above data, and the total reaction time is 2.
It took 1.4 hours.

The obtained latex was coagulated and washed in the same manner as in Example 3, and then dried at 200° C. for 16 hours.

The appearance of the extrudate after extrusion using RR710 was D.

Stretchability was good, and in the adhesion test, it was peeled off with a peel strength of 4.1 kir/co+, whereas other Examples and Comparative Examples did not peel off. The transparency of the fired product was also poor.

Comparative Example 3 In Example 4, the amount of ammonium persulfate charged was changed to 22.
5. The reaction was carried out in the same manner except that the amount of DSAP charged was changed to 750.degree. C. and the reaction temperature was kept constant at 70.degree. C., and the reaction was terminated when the 1495H TFE monomer was consumed.

Total reaction time was 15.3 hours. The obtained latex was treated in the same manner as in the example to obtain fine powder.

The obtained polymer has a high SSG of 2.180.

1? The r1710 extrusion pressure was 636 kg/-, and the appearance of the extrudate was A, but it was unsatisfactory compared to Example 4 in the MIT test.

Comparative Example 4 Commercially available modified polytetrafluoroethylene fine powder TEFLON-62J (LOT162085)
were measured. 995 infrared absorption spectrum band
cm-' absorption was observed, and the performance was similar to that of Comparative Example I in terms of 0 quality, in which the modifier content was determined in the same manner as in the Examples.

Claims (1)

[Claims] 1. Tetrafluoroethylene and general formula, X(CF_2)
_nOCF=CF_2 (wherein, X represents a hydrogen, chlorine or fluorine atom, and n represents an integer from 1 to 6) and C_3F_7
(OCF_2CF_2CF_2)_m(OCF(CF_
3) CF_2)_lOCF=CF_2 (in the formula, m and l
represents an integer from 0 to 4, but these cannot be 0 at the same time); The amount is 0.02
~0.3% by weight number average particle size 0.05-0.6 μm
An aggregate of colloidal particles of 38% of the copolymer.
Specific melt viscosity at 0℃ is 6.0×10^1^0~30
×10^1^0 poise, standard specific gravity is 2.135 ~
2.175, and the green elongation of the paste extrudate is 500%.
A modified polytetrafluoroethylene fine powder characterized by the above. 2. The content of fluoroalkyl vinyl ether is 0.03
The modified polytetrafluoroethylene fine powder according to claim 1, which has a content of 0.2% by weight. 3. Specific melt viscosity is 8.0 x 10^1^0 ~ 25 x 10^
The modified polytetrafluoroethylene fine powder according to claim 1 or 2, characterized in that it has a poise of 1^0. 4. The modified polytetrafluoroethylene fine powder according to any one of claims 1 to 3, which has a standard specific gravity of 2.140 to 2.170. 5. The modified polytetrafluoroethylene fine powder according to any one of claims 1 to 3, which has a standard specific gravity of 2.140 to 2.160. 6. Fluoroalkyl vinyl ether is C_3F_7O
The modified polytetrafluoroethylene fine powder according to any one of claims 1 to 3, wherein CF=CF_2 or C_4F_9OCF=CF_2. 7. Fluoroalkyl vinyl ether is ClC_3F_
The modified polytetrafluoroethylene fine powder according to any one of claims 1 to 4, wherein 6OCF=CF_2. 8. Fluoroalkyl vinyl ether is C_3F_7 (
OCF(CF_3)CF_2)_lOCF=CF_2(
The modified polytetrafluoroethylene fine powder according to any one of claims 1 to 5, wherein l represents an integer of 1 or 2. 9. In an aqueous medium containing 0.03 to 0.3% by weight of a water-soluble fluorine-containing dispersant, tetrafluoroethylene is mixed with the general formula:
X(CF_2)_nOCF=CF_2 (wherein,
(OCF(CF_3)CF_2)_lOCF=CF_2
(In the formula, m and l are integers of 0 to 4, however, m and l are not 0 at the same time.) Together with at least one fluoroalkyl vinyl ether selected from the compounds represented by the formula, reaction pressure is 6 to 40 kg/cm^ 2. Temperature 10-9
When copolymerizing at 5°C, after the start of polymerization, the amount of the final polymer produced is at least 10% by weight and 85%
Before polymerization, (a) add an underwater radical scavenger to the polymerization system in an amount of 0.2 to 5% by weight of the number of moles of the polymerization initiator used.
Add twice the amount, or (b) raise the temperature of the polymerization system to 10 to 4
Tetrafluoroethylene characterized by changing the polymerization conditions by lowering the temperature by 0°C and the general formula,
CF_2)_nOCF=CF_2 (wherein, X represents a hydrogen, chlorine or fluorine atom, and n represents an integer from 1 to 6) and C
_3F_7(OCF_2CF_2CF_2)_m(OC
At least one kind selected from fluoroalkyl vinyl ethers represented by F(CF_3)CF_2)_lOCF=CF_2 (in the formula, m and l represent integers from 0 to 4, however, they cannot be 0 at the same time) Substantially consisting of a copolymer with an olefin, the content of the olefin is 0.02 to 0.3% by weight, and the number average particle size is 0.05 to 0.05.
It is an aggregate of colloidal particles of 0.6 μm, and the specific melt viscosity of the copolymer at 380° C. is 6.0 × 10^1
^0~30×10^1^0 poise, standard specific gravity is 2
．． 135 to 2.175, and the green elongation of the paste extrudate is 500% or more. 10. Modified polytetrafluoroethylene fine according to claim 9, in which the polymerization conditions are changed after 30% by weight of the final polymer is produced and before 70% by weight is produced. How to make powder. 11. Using 2-30 ppm of ammonium or alkali metal salt of persulfate as a reaction initiator, 6-17 kg/c
The method for producing modified polytetrafluoroethylene fine powder according to claim 9, wherein the reaction is carried out at a pressure of m^2. 12. As a reaction initiator, 20 to 1000 ppm of disuccinic acid peroxide and 1/50 to 1/8 thereof
The method for producing a modified polytetrafluoroethylene fine powder according to claim 9, in which double the amount of ammonium persulfate is used in combination and the polymerization conditions are changed according to the method (b). 13. As a water-soluble fluorine-containing dispersant, general formula C_nF_
2_n_+_1COOX or C_3F_7O(CF(C
F_3) CF_2O)_lCF(CF_3COOX (in the formula, n is an integer of 6 to 9, l is an integer of 1 to 2, and X represents an ammonium group or an alkali metal) 0.05 to 0.2% by weight
Ammonium persulfate or an alkali metal salt is used as a reaction initiator at a concentration of 5 to 20 ppm, with a concentration of about 60 to 20 ppm.
The method for producing modified polytetrafluoroethylene fine powder according to claim 9, wherein the reaction is carried out at a temperature of 90°C. 14. Claim 9 or 12 in which 40 to 300 ppm of disuccinic acid peroxide is used in combination with ammonium persulfate in an amount of 1/50 to 1/8 times the amount and at a concentration of 3 to 10 ppm as a reaction initiator. A method for producing a modified polytetrafluoroethylene fine powder as described in . 15. The underwater radical scavenger is at least one selected from aromatic hydroxy compounds, aromatic amines, and quinone compounds having a solubility in water of 2.5×10^-^6 mol/l or more at 25°C. Certain claim 9,
The method for producing a modified polytetrafluoroethylene fine powder according to any one of Items 11 and 13. 16. The method for producing modified polytetrafluoroethylene fine powder according to claim 15, wherein the underwater radical scavenger is hydroquinone. 17, fluoroalkyl vinyl ether is C_3F_7
The modified polytetrafluoroethylene fine powder according to any one of claims 9 to 16, wherein OCF=CF_2 or C_4F_9OCF=CF_2. 18. Fluoroalkyl vinyl ether is ClC_3F
The modified polytetrafluoroethylene fine powder according to claim 9 or 16, wherein _6OCF=CF_2. 19, fluoroalkyl vinyl ether is C_3F_7
(OCF(CF_3)CF_2)_lOCF=CF_2
The modified polytetrafluoroethylene fine powder according to claim 9 or 15, wherein l represents an integer of 1 or 2.