CA1093750A - Process for making cellular polyvinyl chloride products and products thereof - Google Patents

Abstract

PROCESS FOR MAKING CELLULAR POLYVINYL
CHLORIDE PRODUCTS AND PRODUCTS THEREOF

Abstract of the Disclosure Cellular polyvinyl chloride products of good cell quality are made utilizing a lower fusion temperature than conventionally employed by incorporating in a polyvinyl chlor-ide containing plastisol, which has a fusion temperature of from about 200°F. to about 300°F., an effective amount of a blowing agent selected from the group consisting of (1) a mixture of benzene sulfonyl hydrazide and 4,4'-oxybis (benzene sulfonyl hydrazide), (2) a mixture of toluene sulfonyl hydra-zide and 4,4'-oxybis (benzene sulfonyl hydrazide), and (3) 4,4'-oxybis (benzene sulfonyl hydrazide) alone, and an organic base or oxidizing agent which acts as an activator for said blowing agent.

Description

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~, ; Technical Description o~ the Invention Cellular polyvinyl chloride productq find use as gasket-ing and weather Rtripping materials. When placed on a suitable backing, they can be used in such products as carpets, vinyl tiles,~draperles,~and the like. These product~ ara conventionally formed by heating a plastisol comPosition containing a blowing . agent 30 as to decompose the blowing agent with the relea e of ~: gas herefrom. This release of gas as the blowing agen~ is decomposed e:xpands~the plastlsol compositlon to orm the : pol:~vinyl chloride foam product.
Uany blowing agent:acti~ator system~ known to the prior . ~ . ... . .

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~r~7~ c - 4338 art require expansion temperatures that are in the neighborhood of 320F. to 420F. (160C. - 216C.). Such high temperatures, when a non-backed products are desired, require high energy costs. When a backed product is desired, the temperatures cause an additional problem since they are dangerously close to or exceed the degradation temperature of some of the materials which ara used to form the substrate or backing for the desixed product. For example, polypropylene fibers used in carpets degrade at about 290F. to 300F. (143~C. - 149C.). Although lo it is possible to activate some blowing agents, e.g., azodicar-bonamide, 80 that they decompose at lower temperatures, it has been found that their expansion capabilites are very poor as judged by an examination of the cellular structure after the ~ .
;~ foaming operation has been performed. For such systems, a -15 higher temperature range of 320F. - 420F. (160C~ - 216C.) is neaded, if a fine foam structure is desired~ Use of these higher temparatures can, as noted above, be a detriment to any heat sensitive materials that might be present, e.g., synthetic carpat material. Hence, a need exists, particularly when a backed product is desired, for a blowing agent system which can be used at lower temperaturesand which produce~ a fine quality foam.
Although there are ~ome blowing agents which decompose at a relatively low temperature of about 200 - 260F. (93 -127C.), without activation, they are generally not suitable ; ~ for expanding a polyvlnyl chloride composition since they produce a high density foam, with formation of either toxic

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gases or a toxic residue, a malodorous residue, or discoloration of the resulting foam. For example, both benzene sulfonyl hydrazide and toluane sulfonyl hydrazide when used alone, produce high density, malodorous foams.
The present invention is an improved process for forming a cellular polyvinyl chloride product, and the product thereof, which comprises the use of a novel and unobvious low temperature blowing agent-activator system. The use of this process allows a person of ordinary skill in the art to foam a cellular poly-vinyl chloride at generally lower temperatures than convention-ally possible without the formation of toxic or malodorous products, without di.scoloration of the product resulting from the process, and, when a backed product is desired, without loss of the physical and aesthetic properties of any heat sen-sitive materials adhering ~o the backing.
It has been found that polyvinyl chloride backed products of superior cell quality can be formed by use of an effective amount, e.g., from about 0.5% to about 20% by weight, preferably from about 3% to about 15%, based on the weight of the plastisol composition, of a blowing agent-activator system which comprises either (1) a mixture of benzene sulfonyl hydrazide and 4,4'-.~
oxybis (benzene sulfonyl hydrazide), (2~ a mixture of toluene sulfonyl hydrazide and 4,4'-oxybis (benzene sulfonyl hydrazide), ~or (3~ 4,4'-oxybis (benzene sulfonyl hydrazide) alone, and an organic base or oxidizing agent activator for said blowing agents.
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I either of the ao~ementioned mixtures of blowing agents are

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used, the amount of ~,4'-oxybis(benzene sulfonyl hydrazide) in said mixture should be at least 30~, by weigh~, of said mlxture .
A polyvinyl copolymer having a fusion temperature of from about 200F. to about 300F. (about 93C~ to about 149C.) is used in the plastisol compositiorl described above. The terminology "fusion temperature" as used herein is meant to indicate that temperature at which all of the resin particles become dissolved in the plas~icizers that are present so ~hat such a composition, when cooled from said fusion temperature, produces a homogeneous solid. The use of the copolymer having the above described fusion temperature allows for fusion and expansion of the plastisol containing said copolymer in a temperature range of about 200F. (93C.) to about 300F.
(149C.) with the formation of cells of good quality.
In accordance with the present teachings, a polyvinyl chloride-containing plastisol composition is provided which has a fusion temperature of from about 200~ to about 300F
which comprises an effective amount for foaming of a blowing agent selected from the group consisting of a mixture of benzene sulfonyl hydrazide and 4.4'-oxybis(benzene sulfonyl hydrazide), a mixture of toluene sulfonyl hydra~ide and

4,4'-oxybis(benzene sulfonyl hydrazide) and 4,4l-oxybis-(benzene sulfonyl hydrazide) alone, and an effective amount of a nonvolatile organic base or oxidizing agent activator for the blowing;agent.
In accordance with a further embodiment there is ::
provided an improvement in a process for making a cellular vinyl chloride;product by heating a foamable polyvinyl chloride containing pIastisol wherein the improvement comprises ::
incorporating in the plastisol, which has a fusion temperature of from about 200F to about 300F, an effective amount for ~ .

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foaming of a blowing agent selected from the group consisting of a mixture of benzene sulfonyl hydrazide and ~,4'-oxybis (benzene sulfonyl hydrazide), a mixture of toluene sulfonyl hydrazide and 4,4'-oxybis(benzene sulfonyl hydrazide), and 4,4'-oxybis(benzene sulfonyl hydrazide~ alone, an effective amount of a non-volatile organic base or oxidizing agent activator for the blowing agent.
The basic plastisol composition in which the blowing agent system of this invention is to be used is one which is a foamable plastisol composition i.e., a fluid dispersion of particulate vinyl resin in a plasticizer, which is capable of being converted into a solid foamed product by the application of heat and which contains a copolymer having a fusion tempera-ture in the range described above. The preferred thermoplastic resins which are used in the plastisol are the copolymers of vinyl chloride, such as those copolymers obtained by copolymer-izing vinyl chloride with a minor amount of one or more copoly-merizable monomers, such as vinyl acetate, vinylidene chloride, diethyl maleate and bis(beta~chloroethyl)vinylphosphonate. The vinyl : :
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chloride content in the copolymers should be between about 75% and 85% of the copolymer resin and the relative viscosity (as measured by a 1%, by weight, solution of the copolymer in cyclohexanone at 25C.) should range from about 1.7 to 2.7 in order to obtain the proper fusion temperature~ The particle size o~ the copolymer can be adjusted by regulating the emulsion polymerization reaction according to techniques known in the art so that the above described relative viscosity values are met. A particularly preferred copolymer is one which comprises from about 75% to about 85%,by weight, vinyl chloride, from about 7% to about 13%, vinyl acetate, and from about 7% to about 13% of a bis(hydrocarbyl) vinylphosphonate of the formula X O
' " OR'~
: 15 CH2 = C, - P ~

where X is selected from the group consisting of hydrogen, halogen, cyano, aryl and Cl~-C18 alkyl. R and R' are hydrocarbyl groups obtained by removing a hydrogen from an aliphatic or ~ aromatic group. Preferred groups for R and R' are the sub-:: ~
stituted and unsubstituted Cl - C12 alkyl groups, particularly the halosubstituted C~ - ~8 alkyl groups. A particularly preferred vinylphosphonate is bis (beta-chloroethyl) vinylphos-phonate.
~ The copolymers useful in practicing the present invention are formed using conventional emulsion polymerization procedures which can be used to~formulate vinyl chloride containing po~ymers.
In preparing these copolymers, the selected monomers are dis :

10~3 a~ C-4338 persed in an aqueous medium containing from about 0.03 to 10%, by weight of the monomers, of one or more anionic, non-ionic or cationic emulsifiers, for example) the alkyl carbox-ylic acid salts, the alkyl sufate salts, alkyl sulfosuccinate ` 5 salts, the alkyl aryl ether alcohols and the alkyl aryl polyether sulfate salts. The aqueous monomer emulsion is then heated for about 5 to 24 hours, e.g., at a temperature of from about 30C.
to about 75~C., in the presence of from about 0~05 to 5%, by wei~ht of the monomer mixture, of a water soluble, free radical lo initiating catalyst, for example, ammonium, sodium or potassium persulate, hydrogen peroxide or a redox system comprising a mixture of a pereulfate with an alkali metal bisulfite, thlosulEate or hydrosulfite.
The plastisol composition described above should also ~15 contaln about 25% to about 70%, by weight, based on the total weight of the~plastisol of any of the well known plasticizers for vinyl chlorlde. Included within this class are: dialkyl adipate esters, dialkyl azelates, the compatible glycol di-benzoate esters, the compatible epoxy derivatives including 20 ~ epoxidized tall oil and the compatible epoxy resins, glycollates such~as butyl phthalyl butyl glycollate, mellitates such as the trialkyl trimellltates, the compatible phenoxy compounds, phosphate esters~including triaryl, trialkyl and alkyl-aryl ; combinatlons, derlvatives of orthophthalic acid, such as the 25~ ~ dlal~l and alkyl benzyl o-phthalates, polyesters of~varlous dibasi~c acids with glycols,~suah as adipic, azelaic and phthalic acids with va~ious~glyc~ols~terminating with a monofunctional :
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~3~ C-4338 compound, the compatible pentaerythritol derivatives and the compatible sulfonamide A more compl~te lis~ng of potential plasticizer candidates is found in Modern Plastlcs Encyclopedia, Vol. 51, No. lOA, pages 775-785 (1974).
The blowing agent used in the plastisol is selected from the group consisting of (1) a mixture of benzene sulfonyl hydrazide (available commericially as "Celogen BSH", the pre-~ R
ferred material, ''Genitron BSH" or "Poro~or BSH"), and 4,4'-oxybis (benæene sulfonyl hydrazide), which is commerically IQ available a~ "Celogen OT," the preferred material, "Genitron OB'ror "Porofor DO-44," (2) a mixture of toluene sulfonyl ~) hydrazide (available commercially: "Celogen TSH") and 4,4'-oxybis (benzene sulfonyl hydrazide), and (3) 4,4'-oxybis (benzene sulfonyl hydrazide)~alone. ~When the mixtures described above L5~ are used, the amount of 4,4'-oxybis (benzene sulfonyl hydrazide) ; should be at least 30%, by weight, of said mixture. Preferably, :
an egulmolar amount of either benzene sulfonyl hydrazide or toluene sulfonyl hydrazide, as a first component, is used with an equimolar amount of the oxybis compound as a second component.
~ The~p~resence of the latter compound avoids the odor problems normally associated with use of either of the first two enumera-ted blowing agents alone.
pproximately about 50/O to about 95/0, by weight, preferably ~ ~ ~ about~65% to about 85%, by weight, o~ the blowing agent-activator ~ system is comprised of~one of the akove-described blowing agents.
he remainder comprises;an organic base or oxidiæing agent-activa-tor component. The~activator will therefore comprise about 0.5~ to , ~ 7~

~ C-~338 about 10% by weight of the p].astisol.
The organic base can be any of the non-volatile monoalkyl, dialkyl or trialkyl diamine~ or the dialkyl t~amines including triethylene diamine, the preferred amine, ethylene diamin~, ethylene triamine, propylene diamine and hexamethylene diamine, l'he non-volatile monoalkyl, dialkyl and trialkyl monoamines can also be used. If desired, either urea or alkyl substituted ureas can be used as one of the non-volatlle organic base activators. The alkyl group or yroups in any of the.foregoing amines is preferably a C2 - Cl~ alkyl group.
The preferred oxidizing agent-activator can be a non-volatile diaryl or dialkyl peroxide, such as benzoyl paroxide, the pre-ferred activator, lauroyl peroxide, di-t~butyl peroxide and ; diacetyl peroxide~ The alkyl group is preferably Cl - C12 and the aryl group is phenyl.
The poly~inyl chloride composition comprising the vinyl chloride copolymer resin, plasticlzer, ~ng agent, accelerator and, if desired, fillers, antioxidants, pigments and any other optional ingredients, are thoroughly mixed, e~g., in a Hobart ~20 mixer or in a three roll paintmill, to form a plastisol which can either then be coateA onto a selected substrate or can be left as such. Either of these structures i5 then subjected to a temperature of from about 200F. to about 300F., preferably about 250~F, (121C~ to about 280~F. (138~C.), for about 5 to about 20 minutes to quickly foam the plastisol into a foam of superior~quality.
The present invention is illustrated with the following ~ Examples:
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3~P5~ c-4338 This example illustrates the formation of a vinyl chloride-vinyl acetate-bis (beta chloroethyl) vinylphosphonate emulsion copolymer suitable for use in practicing the present invention.
The procedure utilizes a sequence of polymerization steps. The monomer weight ratio in all steps is 80 parts vinyl chloride, ll parts vinyl acetate and 9 parts bis (beta chloroethyl) vinylphos-phonate.
A portion of a deionized water charge of 38.5 lbs. was used to dissolve 38.3g of the bis (tridecyl) ester of sodium Lo sulfosuccinic acid (sold as Aerosol-TR, American Cyanamid Co.), 19.5g of potassium persulfate, and 7.3g of sodium bicarbonate.
The remainder of the water was added and the mixture was charged into the reactor. To this mixture was added 1 lb. 7 1/4 oz. of bis (beta chloroethyl) vinylphosphonate and l lb. 12 l/2 oz. of vinyl acetate. The reactor was closed, and the mixture was stirred briefly. The agitation was stopped and the reactor was evacuted three times with the vacuum being brokén with vinyl chloride monomer. After the third evacuation, 12 lbs. 14 oz.
of vinyl chloride monomer was charged into the mixture. The agitator was turned on, and the mixture was heated to 51C.
The reactor was held at this temperature for about six hours until a 40 lb./in2 drop in pressure from the levels noted at the beginning of the reaction occurred. At this point, the reactor :
was vented and allowed to cool. The aqueous emulsion had a solids content of ~bout 27% of the desired copolymer product which is called product "A".
A 7 lbo 2 l/2 oz. portion of the product from the preceding step was used as a seed in another similar aqueous emulsion 3~o~

polymerization. The amounts of reagents used in thi.s step are:

Vinyl Acetate : 1 lb. 8 l/2 oz.
Vinyl Chloride : 11 lb. 3 1/2 oz.
Bis (beta chloro-ethyl) vinyl,phosphonate : 1 lb. 4 oz.
Deionized ~ater : ~1 lb. 1~ 1/2 oz.
~Aerosol ~R-70 : 14.6 g.
Potassium persul~ate : 14.6 g.
NaHCO3 : 7-~ g-lo The product from this step, called product l'B"~ i5 a larger particle than was produced in the first polymerization step.
A similar portion o product "B" was used as a .;
seed in another polymerization~similar tojthe second poly-merization set forth above. The aqueous emulsion which re-sulted therefrom contained Product."C".
A 3 lb. 9 1/4 oz. portion of product A and a 3 lb.
9 1/4 oz. portion of product C were used as a seed in a final polymerization procedure., The same reagents used in the second polymerization step above were again employed. The product from this step was used in Example 2.

~ low ~usion polyvinyl chloride resin composition was formed by admixing loo parts by weight of the copoly~er of Example 1, loo parts by'weight of a plasticizer composite eomprising 80~o butyl benzyl phthalate and 20~o HB-40, a par-tially hydrogenated terphenyl plasticlzer sold by Monsantog 40 parts by weight of:calcium carbonate iller, and 8 p~rts by weight'of benzoyl peroxide paste~ To this composition was added varying~amounts of benzene sulfonyl hydrazide 3 ~ elogen BS~) and 4,4i-oxybis (benzene sul$onyl hydrazide) (~elogen OT). The compositlons were expanded by heating to 260F. (127C.) for lo minutes. The Table sets ~orth the results that were obtained: ~

~ 3 c-4338 AMOI~TS (/~ O~ REAGENTS
PEROXID3~ FOA~I DENSITY
FORMUIAT:I:ON CELOGEN BSE~ CELOGEN OT PAST.l~ (lbS/ft ~_ ~ ~~ ~ 3 ~ 33 25 ~ 6*
2 ~ ~33 1~67 3 ~33 25~ 7 3 2~5 2~5 3~33 25~4 4 1~67 3~i3 3~33 25o~;
~~~ 5 3 ~33 31~ 1 All concentra~ons are expressed as weight % based on the Lo weigh~ of polyvin~l chloride copolymer~ plasticizer com po~ition and CaC03 filler, *Malodorous fo~m.
When Celogen ssH was used at 5% with no peroxide paste and no Celogen OT, the malodo~ousfoam had an unaccepta-L5 ble density of 53.8 lbs/ft.3. Use of Celogen OT alone with no peroxide paste yielded a composition which did not foam.
. EXAMPLE 3 A foamable polyvinyl chloride composition was fabri cated by admixing 100 parts by weight of the copolymer o ~o Example 1, llo parts of a plasticizer composite which com prised 70 parts by weight butyl benzyl phthalate, 30 parts dioctyl phthalate and lo parts of a secondary plasticizer (Escoflex 175, sold by East Coast Chemicals Co.),40 parts by weight of CaC03 fillerJ and varying amounts of different '5 bl.owing agents. The composition also contained varying amounts of different amines for acceleration. The Table given be~low sets Eorth the results. In all cases the total concentration of blowing agent was 3.2~ based on the weight of polyvinyl chloride copolymer, CaCO~ filler3 and plasti-i~ c;zer composite.

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TABLE II
AMOUNT (% BY WEIGXT) FOBMULATION FOAM DENSITY
NO7 ~L~ G ~ ~ AMINE ACCELERATOR
l BS~ : 1.6 TEDA : 1.6 20.5 OT : 1~6 2 BS~ : 1.6 TEDA : 0~8 22.9 OT : 1.6 3 BSH : 1.6 TEDA : 0.4 26.2 OT : 1.6 4 BS~I : 1.6 Dabco : 0.8 23.3 OT : 1.6

5* BS~ : 1.6 TEDA : 0.8 32.0 AZ : 1~6

6* OT : 1.6 TEDA : 0.8 38.2 AZ : 1.6

7* BSH ~ - NEM : 0,8 46.0**
OT : 1~6

8* AZ : 3.2 TEDA : 0.8 52.8**
:

: ~ All~amount~ are % by weight based on the weight of PVC copolymer, 20 : CaCO3 and plasticizer.
: Abbràviations: BSH = benzene sulfonyl hydrazide (Celogen BSH); OT = 4,4i-oxybis ~benzene~ulfonyl hydrazide) Celogen OT, ~EM = ~-ethyl morpholine; Dabco~- Dabco R-8020, sold by Air Products and Chemica~s, Inc. (triethylanediamine dissolved in alkanolamine).
The compositions set forth above w~re expanded by heating to 260~F. (127C.) for 10 min.
* ~or comparison~; ~ot part of the present invention.
** Poor expansion was noted~
Use of O . 8% TEDA with 3 . 2% OT and o.8% TEI)A with 3 . 2% BSH, ~ ~ : respectively, ln ~two ~eparate foams gave densities of 19.6 and ; ~ 25 lbs/rt3, xespectively.
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~ A urea act~vated~foam was foxmed by the same procedure.
: ~ :
~35 ~ ~described in Example 2. The following reagents were used:

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~-4338 REAGE~TA~o~NT (in qramsl Vinyl chloride/vinyl acetate/
bis (beta-chloroethyl) vinyl phosphonate copolymer (85/10/5 pbw)* 100 Butyl benzyl phthalate 75 CaC03 filler 30 Plasticizer (sanitizer 213) 35 4,4'-oxybis (benzene sulfonyl hydrazide) 8 10 Urea 4 TiO2 . 2 ABC-2** 2 -* formed by a similar procedure to that shown in Example l.
** ~ proprie~ary liquid zinc stabilizer for polyvinyl chloride, 501d by Advance Division, Carlisle Chemical Works, Inc., New Brunswick, N.J.
The foregoing illllstrates certain preferred embodi-ments of the claimed invention. The scope of protection sought is set forth in the claims which follow.

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Claims (28)

1. What is Claimed:
   l. In a process for making a cellular polyvinyl chloride product by heating a foamable polyvinyl chloride containing plastisol wherein the improvement comprises incorporating in the plastisol, which has a fusion temperature of about 200°F.
   to about 300°F., an effective amount for foaming of a blowing agent selected from the group consisting of a mixture of benzene sulfonyl hydracid and 4,4'-oxybis (benzene sulfonyl hydrazide), a mixture of toluene sulfonyl hydrazide and 4,4'-oxybis (benzene sulfonyl hydrazide), and 4,4'-oxybls (benzene sulfonyl hydrazide) alone, and an effective amount of non-volatile organic base or oxidizing agent activator for said blowing agent.
2. 2. A process as claimed in Claim 1 wherein the amount of blowing agent ranges from about 0.5% to about 20% by weight of the plastisol.
3. 3. A process as claimed in Claim 1 wherein the amount of blowing agent ranges from about 3% to about 15% by weight of the plastisol.
4. 4. A process as claimed in Claim 1 wherein the organic base activator is selected from the group consisting of urea, alkyl substituted ureas, and amines.
5. 5. A process as claimed in Claim 4 wherein the activator is an alkyl di- or triamine.
6. 6. A process as claimed in Claim l wherein the activator is a dialkyl or diaryl peroxide.
7. 7. A process as claimed in Claim 5 wherein the activator is a triethylenediamine.
8. 8. A process as claimed in Claim 6 wherein the activator is benzoyl peroxide.
9. 9. A process as claimed in Claim 1 wherein the plastisol is heated to a temperature of about 200°F. to about 300°F.
10. 10. A process as claimed in Claim 1 wherein the plastisol contains about 25% to about 70% by weight of a plasticizer.
11. 11. A process as claimed in Claim 1 wherein the activator comprises about 0.5% to about 10% by weight of the plastisol.
12. 12. A process as claimed in Claim 1 wherein the blowing agent is present in an amount of from about 50% to 95% by weight of the amount of blowing agent and activator.
13. 13. A process as claimed in Claim 1 wherein the plastisol comprises a copolymer of from about 75% to about 85%, by weight, vinyl chloride, from about 7% to about 13% vinyl acetate, and from about 7% to about 13% bis (beta-chloroethyl) vinylphosphonate.
14. 14. A process as claimed in Claim 1 wherein a substrate is coated with the foamable plastisol and the plastisol is thereafter heated.
15. 15. A polyvinyl chloride-containing plastisol composition having a fusion temperature of from about 200°F. to about 300°F.
    which comprises an effective amount for foaming of a blowing agent selected from the group consisting of a mixture of benzene sulfonyl hydrazide and 4,4'-oxybis (benzene sulfonyl hydrazide), a mixture of toluene sulfonyl hydrazide and 4,4'-oxybis (benzene sulfonyl hydrazide) and 4,4'- oxybis (benzene sulfonyl hydrazide) alone, and an effective amount of a non-volatile organic base or oxidizing agent activator for said blowing agent.
16. 16. A composition as claimed in Claim 15 wherein the amount of blowing agent ranges from about 0.5% to about 20%
    by weight of the plastisol.
17. 17. A composition as claimed in Claim 15 wherein the amount of blowing agent ranges from about 3% to about 15%
    by weight of the plastisol.
18. 18. A composition as claimed in Claim 15 wherein the activator is selected from the group consisting of urea, alkyl substituted ureas, and amines.
19. 19. A composition as claimed in Claim 18 wherein the activator is an alkyl di- or triamine.
20. 20. A composition as claimed in Claim 15 wherein the activator is a dialkyl or diaryl peroxide.
21. 21. A composition as claimed in Claim 19 wherein the activator is triethylenediamine.
22. 22. A composition as claimed in Claim 20 wherein the activator is benzoyl peroxide.
23. 23. A composition as claimed in Claim 15 wherein the plastisol contains about 25% to about 70% by weight of a plasticizer.
24. 24. A composition as claimed in Claim 15 wherein the accelerator comprises about 0.5% to about 10% by weight of the plastisol.
25. 25. A composition as claimed in Claim 15 wherein the plastisol comprises a copolymer of from about 75% to about 85%, by weight, vinyl chloride, from about 7% to about 13% vinyl acetate and from about 7% to about 13% bis (beta-chloroethyl) vinylphosphonate.
26. 26. A composition as claimed in Claim 15 wherein the blowing agent is present at from about 50% to about 95% by weight of the amount of blowing agent and activator.
27. 27. The product resulting from the process of Claim l.
28. 28. The product resulting from the process of Claim 14.