CA1274982A

CA1274982A - Blowing agent composition

Info

Publication number: CA1274982A
Application number: CA000532870A
Authority: CA
Inventors: Donald George Rowland; Byron Alexander Hunter; Lee D. Hansen
Original assignee: Uniroyal Chemical Co Inc
Current assignee: Uniroyal Chemical Co Inc
Priority date: 1986-03-25
Filing date: 1987-03-24
Publication date: 1990-10-09
Anticipated expiration: 2007-10-09
Also published as: IN168024B; PH23603A; EP0239200B1; ES2016343B3; JPH0627210B2; US4655962A; KR870008951A; BR8700707A; KR910005568B1; JPS62236836A; DE3763999D1; EP0239200A3; EP0239200A2

Abstract

A blowing agent composition, comprising: (i) azodicarbonamide; (ii) zinc oxide and/or zinc carbonate;
and (iii) at least one member selected from the group consisting of zinc salts of C1-C6 organic acids, and C1-C6 organic carboxamides characterized by a high gas evolution rate. The blowing agent composition may be used in effective amounts in formulations containing a foamable polymer to yield an efficiently gas expanded polymeric composition upon exposure to heat. Suitable C1-C6 organic acids for said zinc salts include straight chain carboxylic acids, and useful organic carboxamides include formamide.

Description

. ~a il~3~ ~

BLOWING AGENT COMPOSITION

BACKGROUND OF THE INVENTION
Field of the Invention .
The present invention relates to an improved blowin~
- agent composition, comprised of (i~ azodicarbonamide:
(ii) at least one ~ember selected from the group consist-ing of zinc oxide and zinc carbonate; and (iii) at least one member selected from the group consisting of the zinc salts of Cl-C6 organic acids and Cl - C6 carboxamides.
In other aspec~s, this invention relates to the prepara-tion and use of such blowing agents, as well as to foamable polymeric compositions comprising foamable polymers and such blowing agent composi~ions.

Description Of Related Art In the manufacture of expanded polymeric materials (such as polyurethanes, polvolefins and the like) the polymeric material is conventionally mixed with a blowin~
agent which, upon exposure to elevated temperature conditions, decomposes to form gaseous decomposition products for expansion of the material.
Among conventionally employed blowin~ a~ents, azodi-carbonamide has come into widespread usage, largely due to its broad applicability in plastics and elastomers.
Moreover, this blowing agent is non-toxic, odorless and non-flammable in character, and its decomposition products present no dangerous health hazard~. Howover, azodiearbonamide has the disadvantage that its deaomposition temperature is relatively high, 210'C, rendering it di.fficult to utilize with many polymeric materials -- partieularly those having low softening temperatures or which are otherwise susceptible to thermal degradation or deterioration. Consequently, when used with polymerie materials having such disadvantageous thermal characteristies, it is desirable to add a deeomposition accelerator (activator) to lower the deeomposition temperature of the azodiearbonamide blowing agent.
Among the aetivators useful for redueing the lS deeomposition temperature of azodicarbonamide are lead, zinc, tin and eadmium oxides, urea and various amines.
While tha use of sueh aetivators reduaes the otherwise undesirably high deeomposition temperature of azodiearbonamide, sueh activator-eontaining blowing ~0 agent eompositions have the disadvantage that the rate and level of gas evolution at lower temperatures is undesirably low. Specifically, the amounts and rate of gas formed on decomposition of azodicarbonamide under low temperature aetivated conditions are less than those amounts obtained from decomposition of sueh eompound at its normal high deeomposition temperature.
As a result of the foregoing disadvantages, azodicarbonamide has been somewhat limited in the low -~, temperature commercial manufacture of foamed (expanded) products.
It therefore would be highly desirable to provide azodicarbonamide in a blowing agent composition wherein the decomposition temperature for such compound is reduced and wherein the adverse impact on the volume of gas and gas evolution rates obtained therefrom is reduced or eliminated.
U.S. Patent 4,312,776 to Puri et al discloses a blowing agent composition comprising azodicarbonamide, a chromium sulfate and at least one zinc compound selected from zinc salts and oxides.
A blowing agent composition comprising (a) azodicar-bonamide, (b) zinc oxide, zinc carbonate or a zinc salt of Cl-C4 organic acid, and (c) an aromatic sulfinic acid or a metal salt of an aromatic sulfinic acid is disclosed in U.S. Patent 4,444,679 to Rowland et al.
Japanese Patent Application 53145876-A describes a foamable vinyl chloride resin composition utilizing as a foaming assistant at least one zinc salt of Cl-C6 organic carboxylic acid and azodicarbonamide. Specific carboxy-lic acids disclosed in this application include formic, acetic, caproic, tartaric and glycolic acids. The zinc salt is employed at a concentration of 0.5-2 weight percent based on the weight of the resin, which in addition to vinyl chloride polymers may also include other polymers such as synthetic rubbers.

4~3 A process for the production of a cellular polychloroprene vulcanizate using azodicarbonamide and at least one metal oxide as a blowing agent is disclosed in U.S. Patent 3,846,350.
Japanese Pa~ent Publication No. 133433 discloses a _ blowing agent composîtion of azodicarbonamide and the reaction product of an amine with a zinc compound.
Zinc'formate compositions are described in British Patent 1,567,417 (use of zinc formate in foamable polyester compositions to impart improved flame retardant properties); U.S. Patent 4,438,223 ( a blowing agent composition comprising æinc formate and certain inorganic and organic alkali metal activators~; Dollimore et al, Journal Of Inorganic Nuclear Chemistry, 29, 621-627 (1967) (disclosing the decomposition behavior of zinc and manganous formates); and Djega-Mariabassou et al, Bull.
Soc. Chim. France, 9, 3166-3173 (1971), "Study of __ _ Decompositions Causing Simultaneous Release of Several Gases, IV - Thermal Decomposition Of Zinc Formate Dihydrate and Morphology of Zinc Oxide Residual"
(describing the decomposition beh~vior of zinc formate and the role of zinc oxide formed during its decomposition). German Offenlegungsschrift 2,148,099 described the expansion of thermoplastic polymers using neutral metal salts of formic and/or oxalic acid optionally with a stabilizer such as sodium phosphite.
U.S. Patent 4,554,294 discloses the use of zinc salts of nitro urea in blowing agent compositions.

SUMMARY OF THE INVENTION

In one aspect, the present invention rel~tes to a chemical blowing agent composition comprising ~i) szodicarbonamide; ~ii) at least one member selected from the group consisting of zinc carbonate and zinc oxide;
-and (iii) at least one member selected from the groupconsisting of zinc salts of a Cl-C6 organic acids and Cl-C6 carboxamides.
In one preferred ~spect, the above~described blowing agent composition comprises between about 2 and about 25~, preferably between about 5 and about 25%, and most preferably between about 10 and about 15% by weight of zinc oxide and/or zinc carbonate and between about 0.5 and about 50~, preferably between about 1 and about 40%, and most preferably between about 1 and about 30% by weight of zinc salt and/or carboxamide, based on the weight of azodicarbonamide present in the composition.
In another preferred aspect, the blowin~ agent 2Q composition contains amounts of (ii) zinc oxide and/or zinc carbonate aDd (iii) the zinc salt and/or carboxamide, relative to the amount of (i) azodicarbonamide in the composition, such that the composition releases at least 150 cm3 gas~gram of azodicarbonamide within 15 minutes when heated to 135C.
In a further aspect, ~he blowing agent composition contains essentially no zinc sulfinate or zinc sulfonate compounds.

3$~

Another aspect of the invention rel~tes to a foamable polymeric composition compri.sing (a) a foamable polymer, or monomers or co-reactants polymer~zable under blowing conditions, and (b) an effective amoun~ of a blowing agent composition as described above.
Yet another aspect of the present invention relates to a method of formin~ an expanded polymeric composition comprising blending a foamable polymer with the blowing agent composition as described above to yield a foamable polymeric composition, and exposing said foamable polymeric composition to heat to expand the foamable polymer therein and form the expanded polymeric composition.
A further aspect of the invention relates to a method of making a foamable polymeric composition, comprising blending a foamable polymer with an effective amount of a blowing agent composition as described above.
A still further aspect of the invention relates to a foamed polymeric composition formed by exposure of a foamable polymeric composition, as as described above, to heat.

DETAILED ~ESCRIPTION OF THE PREFERRED EMBODIME~TS
It has been found that the aforementioned temperature disadvantages associated with the use of azodicarbonamide as ~ blowing agent (viz., its high decomposition temperature of 210C) may be overcome and its useful temperature substantially reduced (to low 9~'~

temperatures, e.g., on the order of about 135C) by utiliæing azodicarbonamide in combination with (a) zinc oxide and/or zinc carbonate and ~b) a z~nc 6alt of a Cl-C6 organic acid and/or a Cl - C6 carbox~Mide. These blowin~ agent compositions yield cellular synthetic _ polymeric materials with hi~hly uniform cell structure and, further, reduce the tendency of such polymeric compositions to blister relative ~o foams produced with other kncwn high gas evolution rate compositions.
The reason for the foregoing improvement in blowing and product characteristics is not completely understood, and while we do not wish to be bound by any theory as regards the mechanism of such improvement, it appears that there is a significant synergistic effect associated with the intimate contact of the three components (i.e., the ~i) azodicarbonamide, (ii) zinc oxide and/or zinc carbonate and (iii) a zinc salt of a Cl-C6 organic acid andtor a Cl - C6 carboxamide) of the blowing a8ent composition of the present invention -- as will he apparent from the data set forth in the E~ample~
hereinafter.
The ~lowing agent composition of the present invention thus comprises~ zodicar~onamide; (ii) at least one member of the group consisting of zinc carbonate and zinc oxide; and (iii) at least one member selected from the group consisting of zinc salts of Cl-C6 organic ~cids, and Cl-C6 carboxamides.

Suitable zinc salts useful as component (iii) in the blowing agent composition include salts of Cl-C6 organic acids such as carboxylic acids. The straight chain carboxylic acids, e.g., formic acid, acetic acid, propionic acid, n-butyric acid, n-valeric acid and _ n-hexanoic acid, as well as mixtures thereof, are particularly advantageous in the practice of the present invention.
Among the aforementioned straight-chain carboxylic acids, the preferred Cl-C~ organic acid for the zinc salt is formic acid, whereby the zinc salt is zinc formate.
Such zinc salt may be provided in the blowing agent composition in the form of anhydrous zinc formate or as zinc formate dihydrate, or as mixtures thereof.
Additionally or alternately, component (iii~ of the blowing agent composition of this invention may comprise a Cl - C6 carboxamide. As used herein, the term "Cl - C6 carboxamide" refers to a compound of the structure R-CON(Rl)2 wherein each of the R and Rl substituents ~ay vary independentlv of the others and is selected from hydrogen or Cl - C6 linear or branched alkyl radicals. A
particularly advantageous carboxamide useful in the practice of the present invention is formamide, although other carboxamides such as acetamide, butanamide and N-methylpropanamide and N,N-dimethylbutanamide may also be employed to good effect.
Moreover, mixtures of zinc salts of Cl - C6 organic acids and/or of Cl ~ C6 car~oxam;des may be employed as _9_ component (iii). In the preferred blowing a~ent compositions of the present invention, constituent (iii) is either zinc formate or formamide.
With regard to the performance characteristics of respective blowing agent compositions containing these constituents, rapid high volume gas evolution at a temperature of 135C (utilized hereinafter as a tempera-ture condition representative of desired commercial processing thermal conditions), is more pronounced in the zinc formate-containing composition. Further, the use of zinc formate dihydrate in general provides a shorter initiation time for decomposition of azodicarbonamide than is obtained by the use of anhydrous zinc formate.
However, once decomposition is achieved, both forms of zinc formate evolve gas at about equal rates.
As used herein, "zinc formate" is intended to be broadly construed to include all forms of zinc ~ormate whether or not combined, complexed or otherwise associated with water, and such term thus includes both hydrated and anhydrous forms of zinc formate, e.g., anhydrous zinc formate as well as zinc formate dihydrate, as well as mixtures of such forms of the compound, e.g., a mixture of anhydrous zinc formate and zinc formate dihydrate.
The efficacy of the zinc formate-containing blowing agent compositions of this invention is particularly surprising when one considers that zinc formate itself is a blowing agent with a decomposition temperature of about ~" ~d ~

288C, I~ is completely unexpected that one could combine ~wo high temperature blowing agents (i.e. azodi-carbonamide which decomposes at 210C and zinc ~ormate which decomposes at 288C) with zinc oxide andtor zinc carbona~e and produce a blowing composition with a decomposition temperature of only about 135~C.
Considering further the activating effect of zinc formate on azodicarbonamide, this zinc salt is preferred relative to the zinc sal~s of C2-C6 carboxylic acids.
Although the azodicarbonamide constituent of the blowing agent composition may be utilized in any form suitable for combination with the other components of the composition, it is generally preferable to utilize such material in a particulate form. When utilized in such form, the particle size of the azodicarbonamide may be varied according to the given end-use application and specifi,c performance and product characteristics desired.
In general, however, the mean particle diameter of the azodicarbonamide component is typically of the order of between about 0.5 and about 50 microns, and is preferably between about 2 and abou~ 20 microns. Such azodicarbon-amide particle sizes are particularly suitable in blowing agent compositions utilized to produce cross-linked expanded polymers.
The specific concentrations and relative proportions of (i) azodicarbonamide, (iia zinc oxide and/or zinc carbonate, and (iii) zinc salt of a Cl-C6 organic and/or Cl-C6 carboxamide in ~his blowing agent compositions of th~ in~ention may be varied widely, depending upcn the particular response time (i.e., time between exposure to the elevated temperature condition utilized, and the initial evolution of gas from the composition), gas evolution r~te and gas quantity desired. One ~killed in the art may, however, easily determine by routine experimentation the preferred proportions for a given expandable material and/or end use.
Preferably, for many applications, the blowing agent composition comprises sufficient amounts of (ii) zirc oxide and/or zinc carbonate and (iii) zinc salt of Cl-C6 organic acid and/or a Cl-C6 organic carboxamide, relative to the amount of (i) azodicarbonamide, such that the resulting blowing agent composition evolves at least 150 cm3 gas/gram of azodicarbonamide within 15 minutes when heated to 135C. Such decomposition reaction gas production rate is suitably determined by the procedure of the following test (hereinafter referred to as the "gas evolution test").
In the gas evolution test, which provides a means of evaluating various azodicarbonamide activa~ing systems over a range of temperatures or at a set temperature (which, as indicated, is selec~ed as 135C herein), the blowing agent composition is first prepared by thoroughly mixing its constituents in a Waringl blender. To 0.2 gram of the resulting composition, 5 milliliters of dioctyl phthalate are added. The mixture is placed in a gas e~olution measuring device, in which the non-condensa'~le gas released durin~ exposure of the blowing agent composition to elevated temperature is collected and measured and the measured volume corrected to standard temperature and pressure conditions tSTP).
In ~eneral, the compositions of this invention _ preferably comprise between about 2 and about 25% by weight, more preferably between about 5 and about 20~ by weight, snd most preferably between about 10 and about 15% by weight of zinc oxide and/or zinc carbonate, based upon the amount of azodicarbonamide employed. Moreover, such compositions ~referably contain between about 0.5 and about 50% by weight, more preferably between about 1 and sbout 40% by weight of zinc salt and/or carboxamide, based on the weight of azod;carbonamide present in the composition.
The blowing agent compositions of this invention may further comprise additional suitable materials useful for the foaming operation or to achieve performance or structural properties for the product in its desired end-use application. Such additional optional components include catalysts, surfactants, activators ~such as urea), extenders, antioxidants, stabilizers, fungicides, bacteriostats, UV absorbers and the like.
The blowing agent compositions of the presPnt invention may be employed with any suitable expandable material, Thus, the blowing agent composition of the invention may be utilized in an effective amount in foamable polymeric compositions comprising a foamable -l3-polymer or monomer(s) polymerizable under blowing conditions or co-reactants polymerizable under such conditions. An "efective amount" of the blowing agent composition refers to the amount required to produce the desired degree of expansion of the expandable material - upon exposure to heat.
Expandable materials which ~ay usefully be employed with blowing agent compositions of this invention include natural and synthetic resins, acrylonitrile-butadiene rubbers and blends of acrylonitrile-butadiene rubbers with polyvinylchloride, polyvinylchloride, polyvinylidene chloride, polyvinyl acetate, polyethylvinyl acetate, poly~sters, polyolefins (for example, low and high density polyethylene and polypropylene), modified poly-phenylene oxides, polystyrenes, polyacrylates, naturaland synthetic rubbers (for example, ethylene-propylene rubber, polyisoprene rubber), copolymers of the monomers amongst themselves or with other monomers (for example, copolymers of ethylvinyl acetate and an olefin such as ethylene or propylene), and mi~tures thereof.
Particularly preferred thermoplastic polymeric materia~s include polyolefins (for example, low and high density polyethylenP and polypropylene) and olefin copolymers (for example, copolymers of ethylene and ethylvinylacetate), preferably those which may be cross-linked before expansion, for example, by means of chemical cross-linking agents or by ionizing radiation.

Thermoset~ing ~ er materials which may be used include any type of suitable rubber which is curable or vulcanizable to a solid state, exemplified by natural rubber or synthetic rubbery polymers made from diolefins such as butadiene and isoprene, or their copolymers with styrene, scrylonitril~, and ~he like, as well as butyl rubber, polymerized halo-diolefins, e.g., neoprene, ethylene-propylene copolymers, ethylene-propylene non-conjuga~ed diene terpolymer elastomers and silicone rubbers.
The blowing agent compositions of the invention find general use in foaming expandable materials, especially those which are capable of setting to a normally solid state with sufficient consistency and strength at the processing temperature (either of themselves or as enabled by any confining device utilized in the blowin~
operation) to retain the gas evolved from the blowing agent composition and preserve a suitable structure in the expanded product. The processing temperature utilized in a specific process system will depend upon a number of factors, including the nature of the polymeric material and its visco-elastic properties, the forming equipment used, and the na~ure of the end product desired, etc. In general, for most effective results, it is important that that material being expanded has a consistency and tensile strength sufficient to retain, in the case of cellular structures, the blowing gas in discrete cells, thereby preventing coalescence of the blowing gas resulting in an undesirable coarse cell structure. This may generally be obtalned ln the case of thermosetting resins by adjusting the rate and state of cure to give the eomposition the desired viscosity and strengt~ ~t the speciic gas forming t~mperature employed. In the case of thermoplastic resins, the desired consistencv and strength generally will be achieved by adjusting the temperature until proper viscosi~y is obtained. As mentioned, ~he ~pecific gas forming temperature utilized in a particular system will vary ~ith the blowing agent composition selected and will be selected depending on the polymer or other expandable material involved.
The blowing agent compositions may be mechanically ~ixed with expandable materials and, if desired, other customary adjuvants (such as fillers, plasticizers, stabilizers, antioxidants, W absorbers, and the like) prior to heating the mixture to temperatures at which decomposition of the blowing agent takes place.
~0 In general, the amount of blowing agent composition used with the expandable material may vary widely depending on the previously mentioned factors, as may be determined without undue experimentation by one of ordinary skill in the art. In general, blowing agent composition concentrations of between about 0.05 and about 20~ by weight, with most preferred concentrations typically being between about 1 and about 10% by weight, based on the total weight of the foamable polymer, are employed.
Thus, a foamable pol~meric composition may be formed by blending a foamable polymer with an effective amount of a blowing agent eomposition according to the invention. Upon blending the foamable polymer with such blowing agent composition, the resulting foamable polymeric composition may be exposed to heat to expand the foamable polymer and form an expanded polymeric composition. Depending on the blowing conditions and specific composition of the blowing agent formulation, expanded materials having specific density and other physical and performance characteristics of widely varying character, as necessary and/or desired in a given end-use application, may be produced.
The features and advantages of the present invention are further illustrated with respect to the foll~wing non-limiting Examples, wherein all parts and percentages are by weight, unless otherwise expressly stated.
~Q
Example 1-3 and Comparative Experiments A-E
Cumulative gas evolution was measured at various times for several blowing agent compositions each comprising azodicarbonamide (ADC) and zinc formate dihydrate and/or zinc oxide in the amounts indicated in Table I below. The results of such testing are also summarized in Table I.

9~32 O ~ N u~ O r~
~1 .~ N

N O ~ J 1~ t~ O
~ ~ ~ ~ C~

I o ~ ~ e~ ~ ~ ~ o O ~1 ~ t~

O o~ ~ c~ ~ c~
~:1 O 1 ~1 O
O
.~
';:
o C~ Cr~
~7 O ~ I I ~ ~ u~ C~
~ ~
O ~ ~ ~ ~ ~ ~J O ~ 0~
o ~ I o ~ ~ Lr) ,~ O r~ . .
,~ n L ~
t~ U
I O ~ O ~ cr~
¢ O I I ~ ~ c ~C ~1 U X
C7 Ul o ~ J J~
a) ~ J~
~ ~ ~ ¢
$~ ~ ~n ~o ~ ~ O~
X
~ ~ ~ o~ g a; ~ ^
U~
o-,, v e ~ ~ O~
U ~ ~ ~rl rd 10 0 X C~ ta o ~, tO U~ ~ U
~ ~ ~ U J U ~ ~
K O ~1 td ~,1 O C ~ ~Do~ r O
;~ ~ ~

-18~

The above data show that the three component blowing agent compositions of this invention produces greater quantities of gas more quickly than do compositions comprising only ADC and zinc formate or zinc oxide.

_ Examples 4-7 and Comparative Ex~eriments F-I
Using the gas evolution test, total gas evolution at 135C was determined for blowing agent compositions comprising various concentrations of azodicarbonamide zinc formate dihydrate and/or anhydrous zinc formate andtor zinc oxide. The results are indicated in Table II
below.

-1~
/

o ~ ~ r~ c~ o~1 ' 00 ~D O ~ I ~ 0 o~
~ ~1 ~1 ~ C~

I O ~D ~ c~ ~ ~ u~r--- u~ o l ~ ~ ~ ~ ~ u~
~ ~ c~

O ~D ~ a)u~
O I C`~ I~ O

o Lrl ~ o~ ~ ~ CO
o ~ c~ I ~ ~ I~ o r~

o o L~ D ~ ~ ~1 H1: o ~`1 I I ,_~ In , 1 rl t~)~
O ~i o~ ,i ~D ~ ~D
C ~ O 1 ~1 t $ ~ ~ ~ u~ CO
U V
~ ~a O ~ O d` ~ ~D ~ O OC~
o ~ . ~ ~ ~ ~ u~ I~

.,1 X
C~ U~
U~
J~ 4~
¢
~ o ~
x ~ ~ - l ~l ~ r ~ ~ ~
~ ~ U~
O ~rl J~ _ 0 ~n - ,,~
~a ~ ~ c~
p~ ~ ~1 ^ ~ ~ ~ ~ U cd ~ ~ ~ h ~ S~ ~: ~ J.) X O c~ ,1 0 ~ ~Dcr~ o W ~ ;~ ~: ,~

4~

The above data indicate that three component blowing compositions which comprise zinc oxi~e in addition to azodicarbonamide and either zinc formate dihydrate or anhydrous zinc formate are superior to two component blowing compositions not containing zinc oxide.

Examples 8-11 and Comparative Experiment J-P
Additional blowing agent compositions were prepared containing various concentrations of formamide, as shown in Table III, and the total gas evolution at 135C was determined for each of such samples.

8~

I O C~
o ~ ~ ~ U~ o ~ ~ ~ U~

o l o ~
o ~ I ~ C~ Ir~ ~ ~
~I

I o ~ ~ ~ U~ ~D O
C~ O~1 ~ I ~1 -- I O
oD o ~ I o ~ QO a~ .
r~

I
o I o oo Z I o I o ~
:~: I ~ I o ~ . o~

¢ I O ~ C ~ D a E~ O C~
0 00 ~ U~
O I ~ ~ I
~ I .
U~ ~/~
~ I I ~ I ~ C' O
~1 E
~;
U~
o ~

.6 ~ v a~ ~ 0 ~ c X ~d ~ ~ ~
O O
a~ ~ P~ ,.
~ ~ ~n w o-,l ~ 0 0 IJ ~ d aJ ~ ~d X rl ~ ~n , o E
~ ~ ~ J .
Ei 6 v 1~ ~ ~ ~:: r~
o ~ ~,1 o o ,1 C`~ o tL~ ~ ~ ~ ~ ~

The above data ~nce ~ain demonstrate the synergystic effect ~t lower temperatures of ~bout 135C
of ehe three component blowing a~ent of this invention.

_ In the following Examples, the ingredients utilized in various compositions are identified with reference to the designations shown in Table IV belo~.

ABLE IV
?ngre d i en 'c s SBR-l Styrene-Butadiene ( 24.5~ bound styrene) Synpol*1502, Synpol, Inc.
S8R 2 Styrene-Butadiene (58.0Z bound styrene) Poly~ar*SS255, Polysar Lim~ted.
NBR Acrylonitrile-Butadiene ~32.5~ ACN) Paracril BJLT* Uniroyal, Inc.
15 PVC Polyvinyl Chloride (Tenneco 175) Tenneco Chemical Co.
Extender Oil Naphthenic Oil, ASTM D2226, Type 103(Circosol*[TM] 4240).
Plasticizer-l (Santicizer*154) Mo~santo Co.
Plasticizer-2 Dioctylphthalate.
Carbowax Polyethylene glyrols (Carbowax*4000) ~nion Carbide Corp.
Plasticizer-3 Chlorinated paraffins, 70~ chlorine b~ Wt.
(Chlorowax*70) Diamond Alkali Co.
Stabilizer-l Soybean oil epoxide (Paraplex*G-62, sp. gr.
0.99~ at 15C) Rohm & Haas Co. *
Stabilizer-2 Chemical heat stabilizer (Mark 189A) Argus Chemical Corp.
Resin Aromatic resin (Picco*100) Hercules, Inc.
Antioxidant-l Octylated diphenylamine (Octamine[T~]) Uniroyal, Inc.
Antioxidant-2 Tri(mixed mono-dinonyl)phenyl phosphite (Polygard ITM]) Uniroyal, Inc.
Accelerator-l N-cyclohexyl-2-benzothiazole sulfenamide (Delac-S [TM]) Uniroyal, Inc.
Accelerator-2 Zinc ~alt of 2-mercaptobenzothiazole (~XAF ~TM~) Uniroyal, Inc.
Accelerator-3 2inc dimethyldithiocarbama~e (Methazate lTM]) Uniroyal, Inc.
Accelerator-4 Dipentamethylene thiuram tetrasulfide tSulfads ITM]) ~.T. Vanderbilt Co., Inc.

* Trademark 4 ~3 TABLE IV (cont.) In~redients _ _ _ _ Filler-1 Hydrated Silica ~Hi-Sil 233) PPG Industries, Inc.
5 Filler-2 Clay, sp. gr. 2.6; particle ~ize: ca. g5%
less than 2 micron (Suprex Clay ~TM] J.M.
Huber Corp.
~ Filler-3 Hydrated alumina pigment ~Hydral* 710) Aluminum Company of ~merica.
Filler-4 Ultra-fine magnesium Silicate (Mistron Vapor lTM] Sierra Talc Co.
Carbon Blac~ ~550 FEF black ADC Azodic~rbonamide; ~v. particle size: 3 micron (Celogen lTM] AZ1303 Uniroyal, Inc.
10 DNPT Dinitrosopentamethylene tetramine Opex 93, Olin Urea MB (.75) ;Ure~ masterbatch 75~ active BIK-OT lTM]
- ' R-464, Ware Chemical Corp.
ZPTS Zinc p-toluene 6ulfinate ZFDH Zinc formate dihydr te A2F Anhydrous zinc ~ormate FA ~ormamide DPG MB-352 Diphenylguanadine MB-65% T(DPG) D65, ~Tyrou~h (.65) and Loser, Inc.

Examples 12-14 and Comparative Experiment Q
Two rubber masterbatches were prepared usin~ the following recipes:

* ~rademark .,-~ ' ' .

Masterbatch-l Parts ~ &~
SBR-l 70 Filler-l 30 Filler-2 100 Resin 10 Antioxidant-l 2 ~ Stearic Acid Zinc Oxide 5 Extender Oil 10 Total parts 288 Masterbatch-2Parts~y Wei~ht PVC 50.0 Stabilizer-l 3.0 Stabilizer-2 2.0 Antimony Oxide5O0 Filler-3 60.0 Antioxidant-21.0 Plastici~er-l15.Q
Filler-l 25.0 Filler-4 24.0 Carbon Black10.0 Zinc Oxide 8.0 Antioxidant-l1.0 Plasticizer-215.Q
PlasticizeI-315.0 Total par~ 284.0 Blowing a~ent compositions of the invention (Examples 12-14) were evaluated for the expansion of press molded cellular shoe 601ing while simultaneously curing the polymeric material, versus a compoRition 5 comprising a conventional blowing agent, dinitroso-pen~amethylene tetramine. The compositions and results for these Samples are set forth in Table V below.

2~

. -26-TABLE V
Example or Compara tive ExperimentQ 12 r 13 14 Masterbatch-l288.00 288.00 288.00 288.00.
Delac-S 0.80 0.80 0.80 0.80 DPG MB-352(.65)0.45 0.45 0.45 0.45 Sulfur 2.~0 2.50 ~.50 2.50 BIK-OT MB-464(.75) 3.20 1.33 1.33 1.33 Carbowax 1.00 1.00 1.00 1.00 Blowing Agent*4.00 5.00 5.00 5.00 Total 299.95 299.08 299.08 299.08 Precure 11 min.

Density, g/cm30.47 0.44 0.45 0.49 Compression Set, 50% RT 22 HOurs, % 12 13 14 17 Shrinkage 6 hrs 100C L&W% 2.7-1.0 1.0-1.25 1.25-0.5 0.75-1.0 Average 1.85 1.12 0.88 0.88 * In Comparative Experiment Q, the blowing agent was D~PT.
In Examples 12-14, the blowing agent comprised 4.25 parts ADC, 0.50 part zinc oxide and 0.~5 part of either ZFDH
(in Example 12), AZF (in Ex2mple 13) or FA (in Example 14).
The above data show that decreased shrinkage is encountered in blown compositions produced employing the blowing agent of this invention relative to a commercially employed blowing agent, DNPT.

~ I~?a ~

Example 15 The usefulness of blowing agent compositions of the invention (Example 15) was further evaluated in insulation tubing using the following recipe, ~11 in parts by weigh~, with the results shown in Table VI
below, TABLE VI

Masterbatch-2 284.0 Sulfur . 2.3 Accelerator-4 1.7 Accelerator-3 1.5 Accelerator-2 0.6 Blowing Agent* 31.0 Total parts321.1 Density, g/cm3 Precure 4 in/127C
plus 8 min/149C 0.082 10 min/149C 0.070 6 min/127C
plus 8 min/149C 0.082 * The blowing agent comprised 26.4 parts ADC, 3.1 parts zinc oxide and 1.5 ~arts ZFDH.

This data shows that insulation having desirable properties may be produced employin~ the blowing agents of this invention.

Claims

THE CLAIMS

What is claimed is:

1. A blowing agent composition comprising: (i) azodicarbonamide; (ii) at least one member selected from the group consisting of zinc oxide and zinc carbonate;
and (iii) at least one member selected from the group consisting of zinc salts of C1-C6 organic acids, and C1-C6 carboxamides.

2. The blowing agent composition according to claim 1, wherein component (iii) is a zinc salt of C1-C6 organic acid.

3. The blowing agent composition according to claim 2, wherein said C1-C6 organic acid is a carboxylic acid.

4. The blowing agent composition according to claim 2 wherein said C1-C6 organic acid is selected from the group consisting of formic acid, acetic acid, propionic acid, n-butyric acid, n-valeric acid, and mixtures thereof.

5. The blowing agent composition according to claim 2, wherein said C1-C6 organic acid is formic acid, whereby said zinc salt is zinc formate.

6. The blowing agent composition according to claim 5, wherein said zinc salt is anhydrous zinc formate.

7. The blowing agent composition according to claim 5, wherein said zinc salt is zinc formate dihydrate.

8. The blowing agent composition according to claim 5. wherein said zinc salt is a mixture of anhydrous zinc formate and zinc formate dihydrate.

9. The blowing agent composition according to claim 1, wherein component (iii) is a C1-C6 carboxamide.

10. The blowing agent composition according to claim 9, wherein said C1-C6 carboxamide is formamide.

11. The blowing agent composition according to claim 1 wherein component (ii) is zinc oxide.

12. The blowing agent composition according to claim 1, wherein the azodicarbonamide is in particulate form and has a mean particle diameter of between about 0.5 and about 50 microns.

13. The blowing agent composition according to claim 12 wherein the azodicarbonamide is is particulate form and has a mean particle diameter of between about 2 and about 20 microns.

14. The blowing agent composition according to claim 1, wherein the concentration of component (ii) is between about 2 and about 25% by weight and the concentration of component (iii) is between about 0.5 and about 50% by weight, based on the weight of azodicarbon-carboxamide present in said composition.

15. The blowing agent compositivn according to claim 1, wherein the concentration of component (ii) is between about 5 to about 20% by weight and the concentration of component (iii) is between about 1 and about 40% by weight, based on the weight azodicarbonamide present in said composition.

16. The blowing agent composition according to claim 1, wherein the concentration of component (ii) is between about 10 and about 15% by weight and the concentration of component (iii) is between about 1 and about 30% by weight, based on the weight of azodicarbonamide present in said composition.

17. The blowing agent composition according to claim 1, wherein the amounts of components (ii) and (iii) relative to component (1) in said composition are such that said composition will evolve at least 150 cm3 gas/gram of azodicarbonamide within 15 minutes at 135°C.

18. The blowing agent composition according to claim 1 comprising: (1) azodicarbonamide; (ii) zinc oxide; and (iii) zinc formate or formamide.

19. The blowing agent composition of claim 1 wherein said composition further comprises urea.

20. A foamable polymeric composition, comprising (a) at least one member selected from the group consisting of foamable polymers and monomers or co-reactants polymerizable under blowing conditions, and (b) an effective amount of a blowing agent composition according to claim 1.

21. The foamable polymeric composition according to claim 20, wherein said foamable polymer is polyurethane.

22. The foamable polymeric composition according to claim 20, wherein said foamable polymer is a polyolefin.

23. The foamable polymeric composition according to claim 20, wherein said foamable polymer is a cross linked expandable polyolefin.

24. The foamable polymeric composition according to claim 20, wherein said foamable polymer is a natural or synthetic rubber.

25. The foamable polymeric composition according to claim 20, wherein said foamable polymer is selected from polyvinylchloride; acrylonitrile-butadiene rubbers;
blends of acrylonitrile-butadiene rubbers with polyvinyl-chloride; polyvinylidene chloride; polyvinylacetate;
polyethylvinyl acetate; polyesters, polyolefins; poly-phenylene oxides; polystyrenes; ethylene-propylene rubber; polyisoprene rubber; polymers of halo-diolefins;
polyamides; polyacrylates; copolymers of monomers of the foregoing polymers; and mixtures of the foregoing.

26. The foamable polymeric composition according to claim 20, wherein said foamable polymer is elastomeric or thermoplastic.

27. The foamable polymeric composition according to claim 20, wherein the concentration of said blowing agent is from about 0.05 to about 20% by weight, based on the weight of said foamable polymer.

28. The foamable polymeric composition according to claim 27, wherein the concentration of said blowing agent is from about 0.1 to about 15% by weight, based on the weight of said foamable polymer.

29. The foamable polymeric composition according to claim 28, wherein the concentration of said blowing agent is from about 1 to about 10% by weight, based on the weight of said foamable polymer.

30. The foamed polymeric composition formed by exposure of said foamable polymeric composition of claim 20 to heat.

31. A method of forming an expanded polymeric composition comprising blending an effective amount of a foamable polymer with the blowing agent composition of claim 1, to yield a foamable polymeric composition, and exposing said foamable polymeric composition to heat to expand the foamable polymer therein and form the expanded polymeric composition.