Polyolefin graft copolymers made with fluorinated monomers

Details Polyolefin graft copolymers made with fluorinated monomers Polyolefin graft copolymers made with fluorinated monomers

2001-09-14

2004-10-05

Mullis, Jeffrey (Department: 1711)

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

Synthetic resins

Mixing of two or more solid polymers; mixing of solid...

C525S199000, C525S243000, C525S276000

Reexamination Certificate

active

06800694

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to polyolefin graft copolymers.
BACKGROUND OF THE INVENTION
Polyolefins are relatively inexpensive and are superior in processability, toughness, water resistance, organic solvent resistance, and chemical resistance. However, they lack stability toward an oxidizing environment and are deficient in surface properties such as coefficient of friction and scratch and mar resistance, as well as in oxygen barrier properties.
Fluorinated polymers are characterized by resistance to harsh chemicals as well as stability toward heat, ultraviolet light, high energy radiation, and oxidation. Polyvinylidene fluoride, a member of the class of fluorinated polymers, is a semi-crystalline material with a high dielectric constant that can easily be processed on conventional molding and extrusion equipment. It also has high mechanical and impact strength, and high resistance to creep, fatigue and abrasion. Film made from this polymer has excellent oxygen and moisture barrier properties.
Graft copolymers of polyolefins are of interest because they are capable of possessing some properties of the polymerized grafting monomer as well as of the polyolefin backbone.
U.S. Pat. Nos. 4,806,581 and 4,605,704 disclose a process for making graft copolymers in which liquid monomer and initiator are absorbed into solid polyolefin particles, followed by reaction of the monomer in the particles to produce polymer and graft copolymer simultaneously in the same reactor. The grafting monomers include vinyl monohalides, such as vinyl chloride, and dihalides, such as vinylidene fluoride, which can be mixed with less than 50% of another monomer such as an acrylate or methacrylate ester. The resulting product can be molded to form transparent or translucent molded articles.
There is still a need for an improved process for producing graft copolymers comprising a polyolefin backbone which are useful for forming articles with improved surface and barrier properties as well as improved thermal stability.
SUMMARY OF THE INVENTION
In one embodiment of this invention, a fluorine-containing graft copolymer comprises a backbone of an olefin polymer material to which is graft polymerized (a) at least one fluorinated gaseous monomer having the formula CR
1
R
2
═CR
3
R
4
, where R
1
=H, F, or Cl; R
2
=H, F, or Cl; R
3
=H, F, CH
3
, CF
3
, or Cl, and R
4
=H, F, or Cl, wherein at least two fluorine atoms are present, and, optionally, (b) at least one non-fluorinated monomer selected from the group consisting of (i) vinyl-substituted aromatic, heterocyclic, and alicyclic compounds, (ii) unsaturated aliphatic nitrites, and (iii) unsaturated aliphatic monocarboxylic acids or esters thereof, wherein the total amount of monomers added is about 1 to about 100 parts per hundred parts of the olefin polymer material, and the particulate olefin polymer material has a weight average diameter of about 0.4-7 mm, a surface area of at least 0.1 m
2
/g, and a pore volume fraction of at least about 0.07, and wherein more than 40% of the pores in the particle have a diameter greater than 1 micron.
This graft copolymer is prepared by a process comprising, in a non-oxidizing atmosphere:
(1) treating a particulate olefin polymer material at a temperature of about 10° to about 70° C. with about 0.1 to about 6.0 parts per hundred parts of the olefin polymer material, of an organic compound that is a chemical free radical polymerization initiator and has a decomposition half-life at the temperature used in step (2) of about 1 to about 240 minutes,
(2) increasing the temperature to about 60° to about 115° C.,
(3) adding (a) at least one fluorinated gaseous monomer having the formula CR
1
R
2
═CR
3
R
4
, where R
1
=H, F, or Cl; R
2
=H, F, or Cl; R
3
=H, F, CH
3
, CF
3
, or Cl, and R
4
=H, F, or Cl, wherein at least two fluorine atoms are present, and, optionally, (b) at least one non-fluorinated monomer selected from the group consisting of (i) vinyl-substituted aromatic, heterocyclic, and alicyclic compounds, (ii) unsaturated aliphatic nitrites, and (iii) unsaturated aliphatic monocarboxylic acids or esters thereof, wherein the total amount of monomers added is about 1 to about 100 parts per hundred parts of the olefin polymer material, to produce and maintain a pressure of about 200 to about 900 psi
(4) heating at a temperature within the range specified in step (2) for about 1 to about 6 hours,
(5) cooling to room temperature, and
(6) releasing the pressure to remove unreacted monomer,
wherein the particulate olefin polymer material has a weight average diameter of about 0.4-7 mm, a surface area of at least 0.1 m
2
/g, and a pore volume fraction of at least about 0.07 and wherein more than 40% of the pores in the particle have a diameter greater than 1 micron.
In another embodiment, a fluorine-containing graft copolymer is prepared in a non-oxidizing environment by:
(1) heating a peroxidized olefin polymer material to a temperature of about 60° to about 140° C.,
(2) adding (a) at least one fluorinated gaseous monomer having the formula CR
1
R
2
═CR
3
R
4
, where R
1
=H, F, or Cl; R
2
=H, F, or Cl; R
3
=H, F, CH
3
, CF
3
, or Cl, and R
4
=H, F, or Cl, wherein at least two fluorine atoms are present, and, optionally, (b) at least one non-fluorinated monomer selected from the group consisting of (i) vinyl-substituted aromatic, heterocyclic, and alicyclic compounds, (ii) unsaturated aliphatic nitriles, and (iii) unsaturated aliphatic monocarboxylic acids or esters thereof, wherein the total amount of monomers added is about 1 to about 100 parts per hundred parts of the olefin polymer material, to produce and maintain a pressure of about 200 to about 900 psi
(3) heating at a temperature within the range specified in step (1) for about 1 to about 6 hours,
(4) cooling to room temperature, and
(5) releasing the pressure to remove unreacted monomer.
Another embodiment of this invention comprises a fluorine-containing graft copolymer comprising an olefin polymer backbone to which is graft polymerized about 1 to about 120 parts per hundred parts of the olefin polymer material, of (a) at least one fluorinated monomer having the formula CH
2
═C(R
1
)—(COOR
2
), where R
1
=H, CH
3
, or CF
3
, and R
2
is H or a partially or completely fluorinated C
1
-C
12
alkyl group, and, optionally, (b) at least one non-fluorinated monomer selected from the group consisting of (i) vinyl-substituted aromatic, heterocyclic, and alicyclic compounds, (ii) unsaturated aliphatic nitrites, and (iii) unsaturated aliphatic monocarboxylic acids or esters thereof.
This graft copolymer is prepared by a process comprising, in a non-oxidizing atmosphere:
(1) treating a particulate olefin polymer material at a temperature of about 60° C. to about 125° C. with about 0.1 to about 6.0 parts per hundred parts of the olefin polymer material, of an organic compound that is a chemical free radical polymerization initiator and has a decomposition half-life at the temperature used of about 1 to about 240 minutes;
(2) treating the olefin polymer material at the temperature selected over a time period that coincides with or following (1), with or without overlap, with (a) at least one fluorine-containing monomer having the formula CH
2
═C(R
1
)—(COOR
2
), where R
1
=H, CH
3
, or CF
3
, and R
2
is H or a partially or completely fluorinated C
1
-C
12
alkyl group, and, optionally, (b) at least one non-fluorinated monomer selected from the group consisting of (i) vinyl-substituted aromatic, heterocyclic, and alicyclic compounds, (ii) unsaturated aliphatic nitrites, and (iii) unsaturated aliphatic monocarboxylic acids or esters thereof, wherein the total amount of monomers added is about 1 to about 120 parts per hundred parts of the olefin polymer material, the monomer being added to the olefin polymer material over a time period from 5 minutes to 3-4 hours to provide a rate of addition that is less than about 4.5 pph per minute at any addit

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