JP2780590B2 - Method for producing perfluorocarbon polymer having sulfonic acid type functional group - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a perfluorocarbon polymer having a sulfonic acid type functional group.

[0002]

_2. Description of the Related Art Conventionally, CF ₂ = CFOCF ₂ CF (CF
₃ ) A method for obtaining a perfluorocarbon polymer having a high ion exchange capacity by copolymerization of a monomer having a sulfonic acid functional group such as OCF ₂ CF ₂ SO ₂ F and a fluoroolefin such as C ₂ F _{4 is known} as bulk polymerization or Solution polymerization using a fluorinated solvent such as trichlorotrifluoroethane as a medium has been employed.

However, the use of certain fluorinated solvents, such as trichlorotrifluoroethane, which has been employed in conventional solution polymerization, is limited due to the risk of destruction of ozone in the atmosphere. There has been a demand for the development of alternative solvents.

[0004]

SUMMARY OF THE INVENTION According to the present invention, a perfluorocarboxylic acid polymer having a sulfonic acid type functional group can be obtained easily and with high yield without using the above-mentioned solvent having a high risk of destroying ozone in the atmosphere. Provide a method that can be manufactured at a high rate.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the copolymerization ratio of a sulfonic acid type functional group-containing perfluorocarbon monomer and a perfluoroolefin is 20%. Weight% or more
Method for producing a perfluorocarbon polymer of
3,3-dichloro-1,1,1,2,2-pentaf
Fluoropropane, 1,3-dichloro-1,1,2,2
3-pentafluoropropane, 2,2-dichloro-1,
1,1-trifluoroethane and 1,1-dichloro-1
The present invention provides a method for producing a perfluorocarbon polymer, wherein solution polymerization is carried out using a hydrochlorofluorocarbon selected from fluoroethane (also referred to as HCFC) as a medium.

The HCFC used in the present invention has a boiling point of 20 ° C. to 200 ° C. in view of the recyclability of the medium , the easiness of drying the produced polymer, and the ease of handling at room temperature.
The following HCFC is used.

That is, in the present invention, as a medium, 3,3 -dichloro- 1,1,1,2,2 -pentafluoropropane (also described as CF ₃ CF ₂ CHCl ₂ or HCFC-225ca), 1,3- Dichloro- 1,1,2,2,3-
Pentafluoropropane (CF ₂ ClCF ₂ CHCl
F, HCFC-225cb), 1,1 -dichloro- 1 -fluoroethane (CFCl ₂ CH ₃ , HC
FC-141b) and 2,2 -dichloro-
1,1,1 -trifluoroethane (CF ₃ CHCl ₂ ,
HCFC selected from HCFC-123)
Is used.

As the sulfonic acid type functional group-containing perfluorocarbon monomer used in the present invention, conventionally known or well-known ones can be exemplified in a wide range. Preferred are those of the general formula CF ₂ ＣＦCF—
_{(OCF 2 CFX) p - (} O) q - (CF 2) n - (C
F ₂ CFZ) _m -A (where p is 0-3, m is 0-3,
n is 0 to 12, q is 0 or 1, X is -F or -C
F ₃ , Z is —F or —CF ₃ , and A is a sulfonic acid type functional group). Usually in view of availability, X and Z are -CF _3, p is 0 or 1, m is 0, n is 0 to 8,
q is 0 or 1, and A is-
SO ₂ F is preferred.

Preferred representative examples of the fluorovinyl compound include CF ₂ CFO (CF ₂ ) _1-8 SO ₂ F and CF ₂ CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) _1-8 S
O ₂ F, CF ₂ = CF (CF ₂ ) _0-8 SO ₂ F, CF ₂ = CF (OCF ₂ CF (CF ₃ )) _1-5 SO ₂ F and the like.

In the present invention, a perfluoroolefin such as tetrafluoroethylene and a sulfonic acid type functional group-containing perfluorocarbon monomer as described above are copolymerized in a medium HCFC. the well can be used in two or more, in addition to these monomers, other Pfaff
A fluoromonomer component, for example, a carboxylic acid type functional group-containing perfluorocarbon monomer, CF ₂ ＯＲCFOR _f (R
_f denotes a perfluoroalkyl group having 1 to 10 carbon atoms), or _{CF 2 = CF-CF = CF} 2, CF 2 =
One or two or more kinds of divinyl monomers such as CFO (CF ₂ ) _1-4 OCF ＝ CF ₂ may be used in combination.

Thus, in the present invention, the medium HCF
Since the objective is a perfluorocarbon polymer in which the sulfonic acid type functional group-containing perfluorocarbon monomer is copolymerized at a high ratio by copolymerization in C, the copolymerization ratio of the sulfonic acid type functional group-containing perfluorocarbon monomer is usually 20%. In order to produce a perfluorocarbon polymer in an amount of not less than% by weight, it is desirable to select the use ratio of the above various monomers. In particular, the copolymerization ratio of the sulfonic acid type functional group-containing perfluorocarbon monomer is 25 to
It is preferably selected to produce about 60% by weight of perfluorocarbon polymer.

When the sulfonic acid type perfluorocarbon polymer obtained by the present invention is used as an ion exchange membrane, its ion exchange capacity is selected from a wide range of 0.5 to 2.0 meq gram dry resin. However, by adopting the conditions described below, even if the ion exchange capacity is increased, the molecular weight of the produced copolymer can be increased, and therefore the mechanical properties and durability of the copolymer do not decrease. It is. The ion exchange capacity varies depending on the type of the copolymer even in the above range, but is preferably 0.6 meq / g dry resin or more, especially 0.7 meq / g dry resin or more. It is preferable in terms of mechanical properties and electrochemical performance as an exchange membrane.

Further, the molecular weight of the sulfonic acid type perfluorocarbon polymer obtained in the present invention is important because it relates to the mechanical performance and the film-forming property as an ion exchange membrane.
When expressed in terms of the value of T _Q , 150 ° C. or higher, preferably 17
The temperature is preferably from 0 to 340 ° C, especially about 180 to 280 ° C.

In the present specification, the term “T _Q ”
It is defined as follows: That is, the temperature indicating a volume flow rate of 100 mm ³ / sec related to the molecular weight of the copolymer is defined as T _Q. Here, the volume flow rate is a value in which the copolymer is melted and discharged from an orifice having a diameter of 1 mm and a length of 2 mm at a constant temperature under a pressure of 30 kg / cm ² , and the amount of the copolymer flowing out is expressed in units of mm ³ / sec. It is. In addition,
“Ion exchange capacity” was determined as follows.

That is, the H-type cation exchange resin membrane is 1N
Was left at 60 ° C. for 5 hours in HCI to completely convert to Form H, and washed thoroughly with water so that HCl did not remain. Thereafter, 0.5 g of the H-type membrane was added to 0.1 N NaOH 2
The mixture was allowed to stand at room temperature for 2 days in a solution obtained by adding 25 ml of water to 5 ml. The membrane is then removed and the NaOH in solution
Is determined by back titration with 0.1N HCl.

In the present invention, the copolymerization reaction between a functional monomer such as a sulfonic acid type monomer and a perfluoroolefin is carried out by reducing the amount of HCFC used to 20/1 or less by weight ratio of HCFC / functional monomer. It is preferable that the control is carried out under the control of preferably 10/1 or less. If the amount of HCFC used is too large, there are disadvantages in work operation aspects such as an increase in the size of the reactor or separation and recovery of the copolymer.

Next, in the present invention, 1 kg / cm ²
It is preferable to employ the above copolymerization reaction pressure. If the copolymerization reaction pressure is too low, it is difficult to maintain the copolymerization reaction rate at a practically satisfactory height, and it is difficult to form a high molecular weight copolymer. On the other hand, if the copolymerization reaction pressure is too low, the ion exchange capacity of the resulting copolymer will increase, and the mechanical strength and ion exchange performance will tend to decrease due to an increase in water content.

The pressure of the copolymerization reaction is set at 50 kPa in consideration of a reaction apparatus or a work operation in industrial practice.
g / cm ² or less. Although it is possible to employ a copolymerization reaction pressure higher than this range, the object of the present invention cannot be proportionately improved. Therefore, in the present invention, the copolymerization reaction pressure is 2 to 5
0 kg / cm ^2, preferably best to select from a range of 2~30kg / cm ^2.

In the copolymerization reaction of the present invention, other conditions and operations other than the above reaction conditions can be employed over a wide range without any particular limitation. For example, the copolymerization reaction temperature optimum value can be selected by the kind and reaction molar ratio of Polymerization initiating source since too high temperature or low temperature is usually becomes disadvantageous for industrial practice, 20 It is selected from 90 ° C, preferably from about 30 to 80 ° C.

However, in the present invention, it is desirable to select a polymerization initiator having high activity at the above-mentioned preferable reaction temperature. For example, ionizing radiation having high activity can be employed even at room temperature or lower, but it is usually advantageous to employ an azo compound or a peroxy compound for industrial implementation.

The polymerization initiation sources preferably employed in the present invention are disuccinic peroxide, benzoyl peroxide, lauroyl peroxide, bis ( pentafluoropropionyl) which exhibit high activity at about 10 to 90 ° C. under the above-mentioned copolymerization reaction conditions. ) diacyl peroxides such as peroxide, 2,2'-azobis (2-amidinopropane) hydrochloride, 4,4'-azobis (4-cyano cracking Lien acid), azo compounds such as azobisisobutyronitrile, t
Peroxyesters such as -butylperoxyisobutyrate and t-butylperoxypivalate; peroxydicarbonates such as diisopropylperoxydicarbonate and di-2-ethylhexylperoxydicarbonate; diisopropylbenzene hydroperoxide; Of hydroperoxides.

In the present invention, the concentration of the polymerization initiation source is 0.0001 to 3% by weight, preferably 0.0001% by weight, based on all monomers.
About 2.0% by weight. By lowering the concentration of the starting source, it is possible to increase the molecular weight of the produced copolymer and to maintain a high ion exchange capacity. If the starting source concentration is too high, the molecular weight tends to decrease, which is disadvantageous for producing a high molecular weight copolymer having a high ion exchange capacity. In addition, a molecular weight modifier used in ordinary solution polymerization may be added. In addition, an inert organic solvent can be added as long as it does not inhibit the copolymerization reaction in the present invention and has little chain transfer.

In the present invention, however, it is preferable to control the concentration of the produced copolymer at 40% by weight or less, preferably at 30% by weight or less. If the concentration is too high, difficulties such as an increase in non-uniformity of the copolymer composition and a stop of stirring due to an increase in polymerization torque are recognized.

The sulfonic acid type perfluorocarbon weight body produced in the present invention is used in various fields, and is suitably used, for example, as an ion exchange membrane. When used for an ion exchange membrane, the sulfonic acid type perfluorocarbon weight body can be formed by an appropriate means. For example, if necessary, a functional group is converted into a sulfonic acid group by hydrolysis. Such a hydrolysis treatment can be performed before or after film formation.
Usually, it is desirable to carry out hydrolysis treatment after film formation. Various means can be adopted as the film forming means. For example, a known or well-known method such as hot melt molding, latex molding, or casting by dissolving in an appropriate solution can be employed as appropriate. Furthermore, it is also possible to laminate two or more layers with a membrane having different ion exchange capacities or a membrane having different functional groups such as carboxylic acid groups. Reinforcement with cloth, fiber, nonwoven fabric, etc. can also be added.

The ion-exchange membrane made of the sulfonic acid-type perfluorocarbon polymer produced in the present invention has various excellent performances, and therefore can be widely used in various fields, objects and applications. For example, it is suitably used as diffusion dialysis, ozone generating electrolysis, electrolytic reduction, a diaphragm of a fuel cell, a polymer catalyst, and the like, particularly in the field where contact resistance is required.
Among them, when used as a cation exchange membrane for alkaline electrolysis, it can exhibit high performance in a laminated film with a carboxylic acid type membrane.

For example, an anode chamber and a cathode are partitioned by the above-mentioned cation exchange membrane to form an anode chamber and a cathode chamber, and an aqueous solution of alkali chloride is supplied to the anode chamber to perform electrolysis. Even in the case of a so-called two-chamber tank for obtaining alkali hydroxide, a high-concentration water of 30% or more is obtained by electrolysis at a current density of 5 to 50 A / dm ² using a sodium chloride aqueous solution having a concentration of ² N or more as a raw material. Sodium oxide can be produced stably for a long time with high current efficiency and low cell voltage.

Next, the embodiments of the present invention will be described more specifically. However, it is needless to say that the present invention is not limited by the description.

[0028]

EXAMPLES [Example 1] HCFC-225ca and HCFC-225cb were prepared in 5 each.
64.8 g of HCFC-225 containing 0% by weight, azobisisobutyronitrile (hereinafter referred to as AIBN)
0.08 g and CF ₂ ＣＦCFOCF ₂ CF (CF ₃ ) O
92.2 g of CF ₂ CF ₂ SO ₂ F was charged into a stainless steel autoclave having an inner volume of 0.2 liter and sufficiently degassed with liquid nitrogen. Thereafter, the temperature was raised to 70 ° C., and tetrafluoroethylene was charged to 10.6 kg / cm ² to carry out polymerization. Started. During the reaction, tetrafluoroethylene was introduced from outside the system to keep the pressure constant. After 10 hours, unreacted tetrafluoroethylene was purged to terminate the polymerization, and the obtained polymer solution was coagulated with methanol, washed and dried to obtain a polymer solution.
7.9 g of the copolymer was obtained.

The ion exchange capacity of the copolymer was 1.0 meq / g dry resin. 250 ° C.
Press to form a tough film, 25% N
Hydrolysis with an aOH aqueous solution yielded a sulfonic acid type ion exchange membrane.

Example 2 HCFC-225ca and HC
HCFC-225c instead of FC-225cb mixture
Polymerization and post-treatment were carried out in the same manner as in Example 1 except that 64.8 g of b was used. As a result, the ion exchange capacity of the obtained copolymer was 0.96 meq / g dry resin.

Example 3 Polymerization and post-treatment were carried out in the same manner as in Example 1 except that the polymerization temperature was 60 ° C. and the polymerization pressure was 9.2 kg / cm ² . The ion exchange capacity was 0.92 meq / g dry resin.

Example 4 HCFC-123 60.1
g, AIBN 0.08 g and CF ₂ ＣＦCFOCF ₂ C
92.2 g of F (CF ₃ ) OCF ₂ CF ₂ SO ₂ F was charged into a stainless steel autoclave having an inner volume of 0.2 liter, sufficiently degassed with liquid nitrogen, then heated to 70 ° C., and 10.6 kg / tetrafluoroethylene was added. The polymerization was started up to cm ² . During the reaction, tetrafluoroethylene was introduced from outside the system, the pressure was kept constant, and after 8 hours, unreacted tetrafluoroethylene was purged to terminate the polymerization,
The obtained polymer solution was coagulated with methanol, washed and dried to obtain 17 g of a copolymer.

The ion exchange capacity of the copolymer was 1.05 meq / g dry resin. 25% of the copolymer
When hydrolyzed with an aqueous NaOH solution, a sulfonic acid type ion exchange membrane was obtained.

[0034]

According to the present invention, a perfluorocarboxylic acid copolymer having a sulfonic acid type functional group can be easily produced at a high yield by using HCFC as a polymerization solvent. And a production method which is less likely to cause ozone destruction.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-243608 (JP, A) JP-A-4-33904 (JP, A) JP-A-3-17106 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) C08F 214/18 C08F 216/14 C08F 228/02 C08F 2/06

Claims (2)

(57) [Claims] 1. A sulfonic acid type functional group-containing perfluorocarbon monomer and a perfluoroolefin are copolymerized.
The former copolymer having a copolymerization ratio of 20% by weight or more.
A method for producing a carbon polymer, comprising:
B-1,1,1,2,2-pentafluoropropane,
1,3-dichloro-1,1,2,2,3-pentafluoro
Lopropane, 2,2-dichloro-1,1,1-triflu
Oroethane and 1,1-dichloro-1-fluoroethane
A method for producing a perfluorocarbon polymer, comprising performing solution polymerization using a hydrochlorofluorocarbon selected from the group consisting of: 2. The sulfonic acid type functional group-containing perfluorocarbon monomer is CF ₂ ＣＦCFOCF ₂ CF (CF ₃ ).
A OCF ₂ CF ₂ SO ₂ F, perfluoro olefin Oh tetrafluoroethylene to which is copolymerizable
Claim 1 Symbol placement of how.