Nucleating agents for thermoplastic resins

Claim 2

In an improved process for producing a foam of a thermoplastic resin composition, the improvement characterized in that the process is carried out with a nucleating-effective amount of at least one thermally stable compound which is selected from the group consisting of sulfonic and phosphonic acids and salts thereof, so as to produce a foam having uniformity of cell size, small cell size, and high void content.

Claim 3

Process of claim 1 wherein the nucleating agent is selected from (a) free acids and salts of partially or totally fluorinated aliphatic sulfonic and phosphonic acids, which optionally may contain cycloalkyl groups and/or ether oxygen; and (b) free acids and salts of aromatic sulfonic and phosphonic acids, in which the aromatic ring, optionally, is substituted with alkyl, fluorine-containing alkyl, and/or hydroxyl groups.

Claim 4

Process of claim 1 wherein the nucleating agent is of the formula [Z(CF.sub.2)×(CF.sub.2 CFX).sub.p (R').sub.y (CH.sub.2).sub.z R03].sub.n M wherein: the bivalent groups, except for RO 3 , may be present in any sequence; Z is selected from CCl 3 , CCl 2 2H, H, F, Cl, F, Cl and Br; each X, independently, is selected from H, F, Cl and CF3; R is selected from sulfur and phosphorus; M is selected from H and a metallic, ammonium, substituted ammonium and quaternary ammonium cation; each of x and z, independently, is an integer and is 0 to 20; p is an integer and is 0 to 6; y is 0 or 1; x+y+z+p is a positive integer or, if x +y+z+p is 0, then Z is Cl 3 or CCl 2 H; n is the valence of M; and R' is selected from a C 5-6 perfluorinated alicyclic ring diradical; a C 1-16 perfluorinated aliphatic polyether diradical with repeat units selected from [CF 2 O], [CF 2 CF 2 O], and [CF 2 CF(CF 3 )O]; and a substituted or unsubstituted aromatic diradical, in which case, Z is H.

Claim 5

Process of claim 3 wherein the nucleating agent contains only two of the diradical units selected from (CF 2 ( x , (CF 2 CFX) p , (R') y , and (CH 2 ) z .

Claim 6

Process of claim 4 wherein the nucleating agent has a total of no more than 20 carbon atoms and M is selected from H, K, Na, Ba, Zr, Cr, Ce, Al, Sr, Ca, Zn, Li, Fe, and triethyl ammonium.

Claim 7

Process of claim 5 wherein the nucleating agent comprises at least one salt of the acid of the formula F(CF 2 ) x (CH 2 ) z SO 3 H, in which x is 6 to 12 and z is 0, 1, or 2.

Claim 8

Process of claim 1 wherein the thermoplastic resin is selected from polystyrene, a styrene copolymer, and a blend comprising a styrene polymer.

Claim 9

Process of claim 1 wherein the thermoplastic resin is selected from copolymers of alpha-olefins and alpha, beta-unsaturated carboxylic acids having 3 to 8 carbon atoms, and their metal salts of Groups I to III of the Periodic Chart of the Elements.

Claim 10

Process of claim 1 wherein the nucleating agent is the potassium salt of perfluorooctane sulfonic acid, and the concentration of nucleating agent, based on the composition, is 500-3000 ppm.

Claim 11

Process of claim 1 wherein the thermoplastic resin is a tetrafluoroethylene/hexafluoropropylene copolymer, the average cell size is less than 100 micrometers, and the void content is greater than 60%.

Claim 12

Process of claim 1 wherein the thermoplastic resin is substantially a polyethylene of high density, the average cell size is less than 100 micrometers, and the void content is greater than 50%.

Claim 13

Process of claim 1 wherein the thermoplastic resin is an ethylene/tetrafluoroethylene copolymer, the average cell size is less than 100 micrometers, and the void content is greater than 50%.

Claim 14

Process of claim 12 wherein the thermoplastic resin is an ethylene/tetrafluoroethylene/perfluorobutyl ethylene copolymer.