Method for producing a fluorine-containing polymer

Details Method for producing a fluorine-containing polymer Method for producing a fluorine-containing polymer

1999-04-14

2001-04-24

Zitomer, Fred (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S230500, C526S247000, C526S254000

Reexamination Certificate

active

06221987

ABSTRACT:

The present invention relates to a method for producing a fluorine-containing polymer which is excellent in heat stability and chemical stability and has high transparency.
Heretofore, a non-fluorine type peroxide such as cyclohexyl peroxydicarbonate or diisopropyl peroxydicarbonate, has been used as a polymerization initiator in the production of a fluorine-containing polymer having a fluorine-containing alicyclic structure in its main chain. However, usually, a radical polymerization initiator does not 100% contribute to the polymerization reaction and may contribute only to a level of 20% to the polymerization reaction depending upon the type of the fluorine-containing monomer or the polymerization temperature.
Accordingly, the excess initiator is likely to decompose, and if this decomposition product has poor compatibility with the fluorine-containing polymer, turbidity will form as the polymerization proceeds. If a fluorine-containing polymer having such turbidity is used to produce various molded products such as lenses or transparent plates by high temperature melt molding such as heat deformation processing, compression molding or extrusion molding, there will be a problem such that the molded products tend to be turbid, or bubbling or coloring is likely to result whereby the desired molded product can hardly be obtainable.
Further, also in a case where a molded product is directly produced by bulk polymerization at a relatively low temperature, turbidity is likely to result, and the appearance or the functionality of the molded product tends to be poor. In a case where a fluorine-containing polymer is produced at a high temperature in order to reduce the remaining ratio of an unreacted fluorine-containing monomer or to increase the productivity, if a high temperature decomposable non-fluorine type peroxide such as di-t-butyl peroxide or t-butyl peroxybenzoate is used as a polymerization initiator, there has been a problem of coloring during the polymerization.
On the other hand, a perfluoro(diacyl peroxide) such as [C
3
F
7
C(O)O]
2
or [C
2
F
5
C(O)O]
2
may sometimes be used as a polymerization initiator for a fluorine-containing monomer. However, such an initiator has a 10 hour half value temperature of lower than 30° C. and a low decomposition temperature and thus has a danger of possible explosion, and it is accordingly used as diluted with a solvent. Accordingly, it is likely that the solvent will remain in the produced polymer, which is likely to deteriorate the physical properties.
Further, such a polymerization initiator has a high decomposition rate, and when the polymerization speed of a fluorine-containing monomer is relatively slow, the initiator is likely to be consumed before the reaction adequately proceeds, and it may be required to add the initiator during the polymerization. Therefore, the initiator is required in an amount larger than usual, which tends to lead to the above-mentioned bubbling or coloring during the production of a molded product. Further, it is not practical to use a large amount of the initiator all at once in bulk polymerization wherein it is difficult to remove the heat generated by the reaction, since the reaction rate can not be controlled, and direct production of the molded product tends to be difficult.
It is an object of the present invention to solve the above-mentioned problems in the prior art and to provide a method for producing a fluorine-containing polymer which is excellent in the heat stability and chemical stability and has high transparency.
The present invention provides a method for producing a fluorine-containing polymer, which comprises subjecting the following fluorine-containing monomer (a), (b), (c) or (d) to bulk polymerization by means of a polymerization initiator comprising a fluorine-containing organic peroxide having a 10 hour half value temperature of from 30 to 130° C., to obtain a fluorine-containing polymer having a fluorine-containing alicyclic structure in its main chain:
(a) a fluorine-containing monomer having a fluorine-containing alicyclic structure,
(b) a fluorine-containing monomer having at least two polymerizable double bonds,
(c) the fluorine-containing monomer (a) and the fluorine-containing monomer (b),
(d) at least one fluorine-containing monomer selected from the fluorine-containing monomers (a) and (b), and another fluorine-containing monomer other than the fluorine-containing monomers (a) and (b).
Now, the present invention will be described in detail with reference to the preferred embodiments.
Not only the fluorine-containing organic peroxide to be used in the present invention itself but also its decomposition product which did not contribute to the polymerization initiation reaction, has good solubility in “the fluorine-containing polymer having a fluorine-containing alicyclic structure in its main chain” (hereinafter referred to simply as the fluorine-containing polymer), and accordingly, the fluorine-containing polymer obtained by bulk polymerization is transparent without turbidity Further, in a case where an initiator of the type decomposable at a relatively high temperature is used, the conversion of the fluorine-containing monomer increases, and the fluorine-containing monomer remaining in the fluorine-containing polymer will be very little. Accordingly, a molded product formed by heating or melt molding of the fluorine-containing polymer by e.g. heat modification processing, compression molding, extrusion molding or injection molding (hereinafter referred to simply as the fluorine-containing molded product) tends to hardly undergo modification such as coloring or turbidifying with time by the decomposition of the fluorine-containing monomer.
The term “having a fluorine-containing alicyclic structure in its main chain” is meant for having a structure wherein at least one carbon atom constituting the alicyclic ring is a carbon atom in the carbon chain constituting the main chain, and a fluorine atom or a fluorine-containing group is bonded to at least a part of carbon atoms constituting the alicyclic ring.
The polymerization initiator to be used in the present invention is a fluorine-containing organic peroxide having a 10 hour half value temperature of from 30 to 130° C. The 10 hour half value temperature is a temperature at which the polymerization initiator undergoes thermal decomposition, and the weight of the polymerization initiator becomes a half in 10 hours. A preferred 10 hour half value temperature is from 40 to 100° C. If the 10 hour half temperature is too low, a danger of explosion is likely, such being undesirable, and if the 10 hour half temperature is too high, the reaction temperature tends to be high, whereby the starting material monomer is likely to be evaporated, such being undesirable.
The fluorine-containing organic peroxide is preferably at least one member selected from the group consisting of a fluorine-containing diacyl peroxide, a fluorine-containing peroxydicarbonate, a fluorine-containing peroxyester, a fluorine-containing dialkyl peroxide, and a fluorine-containing diaryl peroxide. A more preferred fluorine-containing organic peroxide is a fluorine-containing dialkyl peroxide.
In the backbone structure of the organic peroxide in the present invention, the alkyl group may be linear or branched, or may be an aralkyl group i.e. an alkyl group substituted by an aryl group.
The fluorine-containing organic peroxide is preferably a perfluoro compound from the viewpoint of the compatibility and the thermal stability. However, some of fluorine atoms in the molecule may be substituted by hydrogen atoms, chlorine atoms or bromine atoms.
Usually, if fluorine atoms are bonded to the carbon atom at the &agr;-position adjacent to a peroxy bond-containing structural portion such as —C(O)OO— or —C(O)OOC(O)—, cleavage of the —OO— bond is likely to take place due to the electron attracting nature, and the initiator will be a low temperature decomposable polymerization initiator. Accordingly, in the present invention, it is preferred that

Affiliated with

Also associated with

Rating

Method for producing a fluorine-containing polymer does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Method for producing a fluorine-containing polymer, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing a fluorine-containing polymer will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2549141