CA1266934A - Styrene/butadiene graft copolymer latex and heat- vulcanizable composition, containing the latter as reinforcing latex, for the production of latex foam - Google Patents
Styrene/butadiene graft copolymer latex and heat- vulcanizable composition, containing the latter as reinforcing latex, for the production of latex foamInfo
- Publication number
- CA1266934A CA1266934A CA000498572A CA498572A CA1266934A CA 1266934 A CA1266934 A CA 1266934A CA 000498572 A CA000498572 A CA 000498572A CA 498572 A CA498572 A CA 498572A CA 1266934 A CA1266934 A CA 1266934A
- Authority
- CA
- Canada
- Prior art keywords
- weight
- latex
- styrene
- graft copolymer
- graft
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F285/00—Macromolecular compounds obtained by polymerising monomers on to preformed graft polymers
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F257/00—Macromolecular compounds obtained by polymerising monomers on to polymers of aromatic monomers as defined in group C08F12/00
- C08F257/02—Macromolecular compounds obtained by polymerising monomers on to polymers of aromatic monomers as defined in group C08F12/00 on to polymers of styrene or alkyl-substituted styrenes
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Graft Or Block Polymers (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Polymerisation Methods In General (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
ABSTRACT
The styrene/butadiene graft copolymer latex of the invention is characterized in that the graft substrate exhibits a comparatively high content of repeating units obtained by polymerization of styrene.
The graft copolymer exhibits correspondingly compara-tively hard and soft regions with a high and a low Tg, respectively.
The vulcanizable compositions of the invention can be used for production of latex foams distinguished by a low compression set in a temperature range from 20° to 70° C, a high tensile strength, and a high elongation at break, and by a high compression resistance.
The styrene/butadiene graft copolymer latex of the invention is characterized in that the graft substrate exhibits a comparatively high content of repeating units obtained by polymerization of styrene.
The graft copolymer exhibits correspondingly compara-tively hard and soft regions with a high and a low Tg, respectively.
The vulcanizable compositions of the invention can be used for production of latex foams distinguished by a low compression set in a temperature range from 20° to 70° C, a high tensile strength, and a high elongation at break, and by a high compression resistance.
Description
~2~33 ~
23443~305 The present invention rela-tes to ~ styrene/but~diene graft copolymer latex ~lseEul as a rein~orcing late~ of a heat-vulcanizable composition Eor -the production oE latex Eoam.
Latex foam ls normally produced according to conventional processes by expanding a vulcanizable composition (which usually comprises a reinforced elastomer component, a vulcanizing agent and conventional additives) with air or another gas, combininy the composi-tion with a gelling agent, such as sodium silicofluoride~
and then vulcanizing the mixture under heating (for example~ see German Patent 1,056,364; German Offenlegungsschrift No. 1~470~810)o Gelling takes place a-t room temperature, under an in~rared zone, ox in the heating-up phase for vulcanization. In case of the non-gel method, special measures for gelling are omitted. ~he thus-produced latex foam has a cellular structure.
Latex foam should exhibit a good property spectrum which can be described by the following combination of characteristics:
(a) high elasticity in a temperature range from 20 to 70 C, i.e. in this temperature range, after a relatively long compression periodr the compression set is to be as low as possible (DIN 53,572);
(b) high tensile strength and high elongation at the breaking point (DIN 53,571~;
(c) the foam density, for a glven indentation hardness, is to be as low as possible (DIN 53,576, economy~; in other words:
for a predetermined foam density, the indentation hardness (compression resistance) is to be at a maximum.
3751/15-ko O.Z. 4033 ~2~33~
23~43-305 The above~described comblnation of properties L~
inadequately realized by the s~ate of the art.
The present in~ention pro~ides ~ late~ co~npris~ng skyrenebutadiene graft copolymer par~icles which have an average particle di.ameter of 120 to 300 nm and are dispersed in the latex;
said graft co~olymer particles consistil~g o~ [A] 3~ ~
65% by weiyht o~ a hard core having a compara~ively high glass transition temperature and ~Bl 35 to 65% by weight of a soft shell having a co~paratively low glass transltion temperature, wherein the weight percentage i.s based on the total weicJht of the graft copolymer;
said hard core ~] being co~po~ed of a gra~t subs~xate which consist~ of an intermediate graft copolymer ~hich is obtained in a two stage poly~erization and comprises 1 ~o 20% hy weight based on the final graft copolymer oi a polystyrene nucleus and a copolymer grafted thereon consistin~ of 86 to 95~ by weight of styrene units and 5 to 14% by weight of 1/3--butadiene units;
and sald so~t shell [B] be~ng composed of a copolymer grafted on ~,he gra~t substrate and consis~ing of ~2 to 70% by weight o~ styrene units and 30 to 38~ by weight of 1,3-butadiene units.
The present invention also provides a process for producing the latex as deiined above, which process comprisesa preparing the graft substrate defined above by semicontinuous emulsion polymerization ancl subjecting the graft substrate w:Lthout .23'~3-305 isolation to a semlcontinuous emulslon polymerlza~ion with ~tyrene and 1,3-butadlene, whexein the process is carried out in the presence of 1 to 6~ by weight oE a fatty acld or resin acid soap as an emulsifier and not more than 0.3'~ by we.t~ht o:E a Inolecular weigh~ regulato.r, the weight percentages belng based on ~he total monomer and ~he graf~lng stages are carried O~lt with in~ensi~
agitation while feeding the emulsifier so as to avoid formation of new particle~.
10The present invenki.on further p.rovides a heat-vulcanizable composition for the produc~i.on of lakex foam, said composition comprising:
a. a heat-vulcanization eff2ctive amount of a vulcanizir~y agen~, and b. a reinforced elastomer component which co~prise~ an elastomer latex and a reinforcing latex, wherein said reinforcing ;~ latex is the latex as defined above and said elastomer latex 1~ an NR latex, an SBR latex which has heen subjected to steps effecting agglomeration o~ the elas~omer parkicles or a mixture of an NR
latex and an SBR la~ex, the latter ha~ing been subjected to ~eps effecting ac~glomeration of the elastomer particules; the rein~orced elastome.r component ha~ a vi~cosity o~ not more than
23443~305 The present invention rela-tes to ~ styrene/but~diene graft copolymer latex ~lseEul as a rein~orcing late~ of a heat-vulcanizable composition Eor -the production oE latex Eoam.
Latex foam ls normally produced according to conventional processes by expanding a vulcanizable composition (which usually comprises a reinforced elastomer component, a vulcanizing agent and conventional additives) with air or another gas, combininy the composi-tion with a gelling agent, such as sodium silicofluoride~
and then vulcanizing the mixture under heating (for example~ see German Patent 1,056,364; German Offenlegungsschrift No. 1~470~810)o Gelling takes place a-t room temperature, under an in~rared zone, ox in the heating-up phase for vulcanization. In case of the non-gel method, special measures for gelling are omitted. ~he thus-produced latex foam has a cellular structure.
Latex foam should exhibit a good property spectrum which can be described by the following combination of characteristics:
(a) high elasticity in a temperature range from 20 to 70 C, i.e. in this temperature range, after a relatively long compression periodr the compression set is to be as low as possible (DIN 53,572);
(b) high tensile strength and high elongation at the breaking point (DIN 53,571~;
(c) the foam density, for a glven indentation hardness, is to be as low as possible (DIN 53,576, economy~; in other words:
for a predetermined foam density, the indentation hardness (compression resistance) is to be at a maximum.
3751/15-ko O.Z. 4033 ~2~33~
23~43-305 The above~described comblnation of properties L~
inadequately realized by the s~ate of the art.
The present in~ention pro~ides ~ late~ co~npris~ng skyrenebutadiene graft copolymer par~icles which have an average particle di.ameter of 120 to 300 nm and are dispersed in the latex;
said graft co~olymer particles consistil~g o~ [A] 3~ ~
65% by weiyht o~ a hard core having a compara~ively high glass transition temperature and ~Bl 35 to 65% by weight of a soft shell having a co~paratively low glass transltion temperature, wherein the weight percentage i.s based on the total weicJht of the graft copolymer;
said hard core ~] being co~po~ed of a gra~t subs~xate which consist~ of an intermediate graft copolymer ~hich is obtained in a two stage poly~erization and comprises 1 ~o 20% hy weight based on the final graft copolymer oi a polystyrene nucleus and a copolymer grafted thereon consistin~ of 86 to 95~ by weight of styrene units and 5 to 14% by weight of 1/3--butadiene units;
and sald so~t shell [B] be~ng composed of a copolymer grafted on ~,he gra~t substrate and consis~ing of ~2 to 70% by weight o~ styrene units and 30 to 38~ by weight of 1,3-butadiene units.
The present invention also provides a process for producing the latex as deiined above, which process comprisesa preparing the graft substrate defined above by semicontinuous emulsion polymerization ancl subjecting the graft substrate w:Lthout .23'~3-305 isolation to a semlcontinuous emulslon polymerlza~ion with ~tyrene and 1,3-butadlene, whexein the process is carried out in the presence of 1 to 6~ by weight oE a fatty acld or resin acid soap as an emulsifier and not more than 0.3'~ by we.t~ht o:E a Inolecular weigh~ regulato.r, the weight percentages belng based on ~he total monomer and ~he graf~lng stages are carried O~lt with in~ensi~
agitation while feeding the emulsifier so as to avoid formation of new particle~.
10The present invenki.on further p.rovides a heat-vulcanizable composition for the produc~i.on of lakex foam, said composition comprising:
a. a heat-vulcanization eff2ctive amount of a vulcanizir~y agen~, and b. a reinforced elastomer component which co~prise~ an elastomer latex and a reinforcing latex, wherein said reinforcing ;~ latex is the latex as defined above and said elastomer latex 1~ an NR latex, an SBR latex which has heen subjected to steps effecting agglomeration o~ the elas~omer parkicles or a mixture of an NR
latex and an SBR la~ex, the latter ha~ing been subjected to ~eps effecting ac~glomeration of the elastomer particules; the rein~orced elastome.r component ha~ a vi~cosity o~ not more than
2,500 mPa s when me~sured wi~h a Bxookfield viscometer at a solid con~ent of 68~ by waight; and the amount of said reinforcin~ latex in the rein~orced elastcmer component l~ 2 to 30 parts by weiyht of solids based on 100 parts by weiyhk of the solids of the two latic~s.
3~
23~3-305 The ~?resent invention still ~urther provides a proce~
for producing the h~at-vulcanlzab].e compo~i tlon as ~le.~in~d ~`
--3~--~':G
Y~
.
~ 3~ 234~3-305 above, which process comprises: mixing -the la-te~ as deEined above as a rein~orciny latex with the elastomer latex as defined above -thereby obtaining a mixture of latices, wherein the amount of said reinforcing late~ in the mixture of latices is 2 -to 30 ~ by weight of solids based on the solids of the two latices, concentrating said mixture until its solid con-centration becomes at least 55 % by weight, and adding a vulcanizing agent in a heat-vulcanization effective amount to the concentrated mixture.
The present invention still further provide~ a latex form produced by the process described immediately aboveO
The styrene/butadiene graft copolymer particles of the latex of this invention can be described in a simplified way as follows: they consist of a comparat,ively hard core (graft substrate) having a comparatively high glass transition temperature and a comparatively soft shell having a comparatively low glass transition temperature.
The first step for producing the latex of the invention is to produce the graft substrate which becomes the relatively hard core after graft copolymerization.
The graft substrate can be a random copolymer of styrene and 1,3-butadiene obtained by a single stage emulsion polymerization. The graft substrate contains 86 to 95, preferably 87 to 93 % by weigh~ of styrene units and correspondingly 5 to 14, preferably 7 to 13 % by weight of 1,3-butadiene units.
The graft substrate, alternatively~ may be itself a graEt copolymer of styrene and 1,3-butadiene. I'his intermediate raft copolymer may be produced by firs-~ polymerizing styrene by ~! 4 ~ `~3~ 234~3-305 an emulsion polymerizatio~ to obtain a polystyrene nucleous latex, then grafting styrene ancl butadiene onto this nucleous latex. The amount of the polystyrene nuclea-tilly la-tex is 1 to 20, preferably, 5 to 15 % by weight (on the solid basis) based on -the final graft copolymer. The graft portion on the polystyrene nucleous latex should consist of 86 to 95, preferably 37 to 93 %
by weight of styrene units and 5 to 14, preferably 7 to 13 ~ by weight of 1,3-butadiene units. The graft polymerization, namely, the second ~tage, should be carried out with intensive agitation while feeding an emulsifier in order to avoid formation of new particles.
The graft substrate produced by the method described above, without isolation, is then subjected to a g~afting process.
This process involves an emulsion polymerization of styrene and 1,3-butadiene on to the graft substrate. The graft substrate and the monomers are employed in amounts such that the resulting graft copolymer consists of 35 to 65, preferably 45 to 60 % by weight of the graft substrate and 35 to 65; preferably 40 to 55 by weight of the portion grafted on the substra-te and that the portion graft~d on the substrate consists of 62 to 70, preferably 65 to 69 ~ by weight of styrene units and 30 to 38, preferably 31 to 35 ~ by weight of 1l3-butadiene units. This emulsion poly-~; meri~a-tion should also be carried out with intensive ayitation while feeding an emulsifier in order to avoid formation of new particles~ The resulting final graft copolymer is present in the disperse phase of the latex~ The graft copolymer particles of the latex have a comparatively hard core (that is the graft substra-te) ~with a comparatively high glass transition temperature (Tg) and a ~ 234~3-305 comparatively soft shell (that is the por-tion gra:Eted on the sub-strate) with a comparatively low y:Lass transition temperature (Tg).
The graft copolymer particles usually ha~e an averaye particle diameter of 120 to 300 nm, preferably 150 to 250 nmt whe~t measured by surface titration (which is also called soap titration). The detailed procedure of the surface titration is described in J. Paint Techn. 47: 41 (1975), right-hand column; last paragraph et seq.
The emulsion polymerization which is employed for pro-ducing the latex of the present inYention is basically known in the art (see for example United States Patent ~os. 2,962,465 and
23~3-305 The ~?resent invention still ~urther provides a proce~
for producing the h~at-vulcanlzab].e compo~i tlon as ~le.~in~d ~`
--3~--~':G
Y~
.
~ 3~ 234~3-305 above, which process comprises: mixing -the la-te~ as deEined above as a rein~orciny latex with the elastomer latex as defined above -thereby obtaining a mixture of latices, wherein the amount of said reinforcing late~ in the mixture of latices is 2 -to 30 ~ by weight of solids based on the solids of the two latices, concentrating said mixture until its solid con-centration becomes at least 55 % by weight, and adding a vulcanizing agent in a heat-vulcanization effective amount to the concentrated mixture.
The present invention still further provide~ a latex form produced by the process described immediately aboveO
The styrene/butadiene graft copolymer particles of the latex of this invention can be described in a simplified way as follows: they consist of a comparat,ively hard core (graft substrate) having a comparatively high glass transition temperature and a comparatively soft shell having a comparatively low glass transition temperature.
The first step for producing the latex of the invention is to produce the graft substrate which becomes the relatively hard core after graft copolymerization.
The graft substrate can be a random copolymer of styrene and 1,3-butadiene obtained by a single stage emulsion polymerization. The graft substrate contains 86 to 95, preferably 87 to 93 % by weigh~ of styrene units and correspondingly 5 to 14, preferably 7 to 13 % by weight of 1,3-butadiene units.
The graft substrate, alternatively~ may be itself a graEt copolymer of styrene and 1,3-butadiene. I'his intermediate raft copolymer may be produced by firs-~ polymerizing styrene by ~! 4 ~ `~3~ 234~3-305 an emulsion polymerizatio~ to obtain a polystyrene nucleous latex, then grafting styrene ancl butadiene onto this nucleous latex. The amount of the polystyrene nuclea-tilly la-tex is 1 to 20, preferably, 5 to 15 % by weight (on the solid basis) based on -the final graft copolymer. The graft portion on the polystyrene nucleous latex should consist of 86 to 95, preferably 37 to 93 %
by weight of styrene units and 5 to 14, preferably 7 to 13 ~ by weight of 1,3-butadiene units. The graft polymerization, namely, the second ~tage, should be carried out with intensive agitation while feeding an emulsifier in order to avoid formation of new particles.
The graft substrate produced by the method described above, without isolation, is then subjected to a g~afting process.
This process involves an emulsion polymerization of styrene and 1,3-butadiene on to the graft substrate. The graft substrate and the monomers are employed in amounts such that the resulting graft copolymer consists of 35 to 65, preferably 45 to 60 % by weight of the graft substrate and 35 to 65; preferably 40 to 55 by weight of the portion grafted on the substra-te and that the portion graft~d on the substrate consists of 62 to 70, preferably 65 to 69 ~ by weight of styrene units and 30 to 38, preferably 31 to 35 ~ by weight of 1l3-butadiene units. This emulsion poly-~; meri~a-tion should also be carried out with intensive ayitation while feeding an emulsifier in order to avoid formation of new particles~ The resulting final graft copolymer is present in the disperse phase of the latex~ The graft copolymer particles of the latex have a comparatively hard core (that is the graft substra-te) ~with a comparatively high glass transition temperature (Tg) and a ~ 234~3-305 comparatively soft shell (that is the por-tion gra:Eted on the sub-strate) with a comparatively low y:Lass transition temperature (Tg).
The graft copolymer particles usually ha~e an averaye particle diameter of 120 to 300 nm, preferably 150 to 250 nmt whe~t measured by surface titration (which is also called soap titration). The detailed procedure of the surface titration is described in J. Paint Techn. 47: 41 (1975), right-hand column; last paragraph et seq.
The emulsion polymerization which is employed for pro-ducing the latex of the present inYention is basically known in the art (see for example United States Patent ~os. 2,962,465 and
4,13~,872) and is conducted in the presence of 1 to 6, preferably 3 to 5 % by weight of a fatty acid or resin acid soap as an emulsi-fier and not moxe than 0.3, preferably not more than 0.2 % by weight of a molecular weight regulator. The weight percentages are bas~d on the total a~tount of monomers. Typical examples of the soap include, for example, an al~ali metal salt of a Eatty acid such as potassium oleate and sodium stearate. Well-known molecular weight regulators include for example, mercaptans such as tert-dodecyl mercaptan. Usually radical polymerization initiators are employed to facilitate the polymerization. Con-venient are water soluble initiators r such as ammonium persulfate.
Since the c~raEt substrate produced by the emulsion polymerizationt without isolation, is grafted according to the invention, the w~lole process may be said to be a semicontinuous emulsion polymerization.
The latex containing the sytrene/butadiene graft copolymer particles thus produced may be used as a reinforcing ~6~33~ 23~13-305 latex for preparing a heat-vulcallizable composition Eor -the production of latex :Eoam according to the invention.
For preparing the heat-vulcanizable composition, the styrene/butadiene graft copolymer latex as a reinforciny latex is mixed with an elas-tomer late~. The amount of the reinEorcing latex is 2 to 30, preferably 5 to 25 % by weight oE solids based on the solids of the two latices. The mixture of the latices thus obtained is concentra-ted until the solid conten-t becomes at least 55~O by weight preferably 60 % by weight.
As the elastomer la-te~, there can be used an NR latex, an SBR latex which has been subjected to steps effecting agglo-meration of the elastomer particles or a mix-ture of the NR latex and the SBR latex. The measures for agglomeration of the elastomer particles of SBR latex are known (see, for example, German Patents 1,213,98~ and 2,6~5,082). The SBR latex is preferably a conventional SBR latex, in other words, it is not carboxylated.
Usually such SB~ latex is produced by an emulsion polymerization in the presence of a conventional fatty acid or resin acid soap as an emulsifier. The SBR normally contains 15 to 35, preferably 20 to 30 % by wei.ght of styxene units.
The mixture of the latices~ after concentration have a viscosity of not more than 2~500, preferabl~ not more than 2,000 mPa s when measured in a Brookfield viscometer (Spindle III~ at 30 rpm and at 20 C) at a solid content of ~8 % by weight.
The thus concentrated mixture of the latices may be used as a reinforced elastomer component of a heat-vulcanizable composition for the production of late~ foam. The reinforced elastomer component is mixed with a vulcanizing agent and i:E
~ 23~3-305 necessary other conventional aclditives.
The vulcanizing agents are to be understood as meaning vulcanizing agents used in conventional vulcanization systems. A
preferred vulcanization system contains sulfur in combination with the usual accelerators. The amount of vulcanizing agent depends on the other mixture components and can be readily determined by simple orientation experiments.
Conventional additi~es are, for example, fat soaps and resin soaps (they can be present in the reinforced elastomer com-ponent in an amount sufficient for further processing of the vul-canizable composition), antiaging and light-protection agents, thickeners, e.g. carboxymethylcellulose, and fillers, such as, for example, chalk, kaolin and amylose (starch).
The invention will be explained by means of the examples set forth below. In these examples/ parts (p) mean parts by weight and percent (~) means weight percentO
The comparati.ve examples not in accordance with the in~ention are denoted by capital lettersO
The viscosities of the reinforced. elastomer components were determined in a Brookfield viscometer (spindle III, 30 rpm.
20C) ~2~ 3~
Productioll of Reinforcing Latices 1 and A-C
______ ~________~_ _______ _______ ________ Example_l (Styrene/Butadiene Graft Copolymer Latex of Xnvention) In a polymerization rea~tor, an emulsion of ~4 p fully demineralized water~ 0O2 p potassium oleate ~solid~
present as a 17% strength aqueous solution~, 0.1 p potas-sium carbonate, 0.015 p tetrasodium salt of ethylene-diaminetetraactic acid, 10 p styrene and 0.15 p a~onium persulfate was heated to 70 C during a period of 1-2 ho~rs.
During this step, a polystyrene nucleating latex ~as obtainad having an average particle diameter of 40 nm.
At 75 C, the followin~ streams were added ~o this batchO
~ 1) A mixture of 19 p fully demineralized water and 4 p potass.ium oleate (solidr present as a 17 strength aqueous solution); feeding period: S hours (constant flow velocity3.
(23 A solution of 1.35 p ammonium persulfate in 6 p ully demineralized water; feeding periodo 6 hours (constant flow velocity)~
(33 A mixture of 45 p styxene/1,3-butadiene (weight ratio: 89/11) and 0O06 p tert-dodecyl mercaptan, feeding period: 2.5 hours (constant flow velocity~.
(4~ A mixture of 45 p styrene/1~3-butadiene ~wei~ht ratio: 67/33) and 0.09 p tert-dodecyl mercaptan;
feeding period: 2.5 hours ~constant flow velocity3~
9;~
Feeding of streams (1) - (3) was begun simulta-neously. After 2.5 hours ~end of the first grafting stage), stream (41 was commenced~
The styrene/butadiene graft copolymer latex ob-tained after termination of the second grafting stage had a solids content of about 50% and an average particle dia~
meter of 220 nm.
Example A ~Styrene/Butadiene Graft Copolymer Latexl This example corresponds to Example 1 regarding the weight ratio of the monomers utiliæed in total ~styrene~1,3-butadiene = 80/20~ and with respect to the remaining production parameters; however, streams ~33 and (4) were replaced by the following stream:
(3~ A mixture of 90 p styrene/1,3-butadiene (weight ratio: 70/20) and 0.15 p tert-dodecyl mercaptan;
fee~ding period: 5 hours (constant flow velocity).
Feeding of streams ~ (31 was commenced simultaneously.
The styrene/butadiene graft copolymer latex obtained after termination of the grafting stage had a solids content of about 50% and an average particle diameter of 200 nm.
~26~3~
le B (Styrene/Butadiene Graft Copol~mer Latex~
This example corresponds to Example l; however~
stream ~4) was replaced by the followiny stream:
(4) A ~ixtur0 of 45 p styrene/1,3-butadiene (weight ratio 72/28) and 0.09 p tert-dodecyl mercaptan;
feeding per.iod: 205 hours ~constant flow velocity).
The styrene/butadiene graft copolymer latex produced after termination of the second grafting stage exhibited a solids content of about 50~ and an avexage particle diameter of ~10 nm~
Example C (Polystyrene La~ex) This example corresponds ~o Example l; however~
streams (3) and (4) were replaced by the following stream~
(3~ A mixture of 90 p styrene and 0O15 p ter~-dodecyl mercaptan; feeding period: 5 hours (constant flow ve~locity).
Feeding of streams (1) - (3) was commenced simultaneous].y.
The polystyrelle latex obtained after poly~
merization was finished had a solids content of about 50 and a~ average particle diameter of 200 nm.
Production of SBR Latex __ __._. ___________ __ The latex was prepared co.nventionally by reclox polymerization with the following formulati.on:
120 p Eully demineralized water 2.7 p potassium oleate (calculated as 100~ strength3 0.5 p of a condensation product from formaldehyde and naphthalenesulfonic acid 0.29 p potassium chloride 31 p styreIIe 69 p 1~3~butadien~
After a 65% conversion of the monomers, poly-merization was stopped. The resultant SBR latex was subjected to the steps indicated in German Patent 1,213,984 for agglomeration o:E the elastomer particles.
The average particle diameter was thereafter 240 nm.
The residual monomers were separated conventionally.
The~polymer contained 26~ repeating units obtained by polymerization of styrene (IR analysis~
Prepaxation of Reinforced Elastomer Components 1 and A-C
The SBR ].atex was mixed respectively with one of reinforcing latices 1 and A-C (solicls: 20 p phr~O
The thus-obtained mixture of latices was concentrated respectively to a solids content of 70~.
With a solids content ~f 68~, -the re.inforced elastomer components had the following viscosities:
l : 1,400 mPa's; A . 1,200 mPa-s;
B : 1,300 mPa-s; and C : 1,350 mPa-s.
Production of Vulcanizable Compositions l and A-C
and Latex Foams ~Test Specimens~ l and A-C
The vulcaniza~le composition~ were produced according to the following formulation (solids~O
lO0 p of one of the reinforced elastomer comp~
nen~s 1 and A-C
0.5 p potassium oleate ~added a~ a 17% stren~th aqueous solution) 0.25 p carboxymethylcellulose (added as a ~.5%
strength aqueous solu~tion) Prior to expansion~ the vulcanizable compositions were finished up by the addition of a 50% strength aqueous dispersion of the following vulcanizing syst~m (solids~:
2 p sulfur l p zinc diethyldithiocarbamate 1 p zirlc 2-mercaptobenzothiazole l p diphenylguanidine 3 p zinc oxide 0.5 p potassium oleate ~added as a 17~ strength aqueous solution) l p antîoxidant ~6~
By means of a whisked-foam producing machine, ~ir was whipped into the vulcanizable compositions. The resultant wet foams (foam density: about 130 g/l) were respectively combined with 2 p sodium silicofluoride~ pres-ent as a 25~ strength aqueous solution, and poured intoheatable molds. By gelling in the heating-up phase and subsequent vuleanizirlg at 100 C/30 min, the latex foams 1 and A-C were obtained. They were washed with water, dried at 75 C/16 h (foam density: 100 g/l), and characterized as indicated in the table below.
~2~
, ~ g ~
~ o o o I ~ ~ Z m I o o ~ N I U~
O
X
Lr) I I O a) I ~ I o o o Lr) I ~ .~J
o o o L~
dP æ I I
V~ 0 ~ I ' E~ Y ~
Ln.n ~ o S:
O ~ o I O
I a~ I o o o o I s:~ ~
X I ~ ~-- H
~ , ~ I I o 3 0 0 1 '~- '- J
M I. ~ h ~ I I r rl i` U~ I I h h ~H I I ts~t~
U Ig I d S I I ~ I~ I ' ~ ~
rl ~ n ,~ o ~ ) o ¦ h ~3 0 I
~ I O ~ 0 O I I ~ ~
~ L~
m m ~?
: i -- 1 5 --~ `
Tes~ specimens A and B show unsatisfactory values for compression set. Test specimen C has inadequat~ data for tensile strength and for elongation at break.
Since the c~raEt substrate produced by the emulsion polymerizationt without isolation, is grafted according to the invention, the w~lole process may be said to be a semicontinuous emulsion polymerization.
The latex containing the sytrene/butadiene graft copolymer particles thus produced may be used as a reinforcing ~6~33~ 23~13-305 latex for preparing a heat-vulcallizable composition Eor -the production of latex :Eoam according to the invention.
For preparing the heat-vulcanizable composition, the styrene/butadiene graft copolymer latex as a reinforciny latex is mixed with an elas-tomer late~. The amount of the reinEorcing latex is 2 to 30, preferably 5 to 25 % by weight oE solids based on the solids of the two latices. The mixture of the latices thus obtained is concentra-ted until the solid conten-t becomes at least 55~O by weight preferably 60 % by weight.
As the elastomer la-te~, there can be used an NR latex, an SBR latex which has been subjected to steps effecting agglo-meration of the elastomer particles or a mix-ture of the NR latex and the SBR latex. The measures for agglomeration of the elastomer particles of SBR latex are known (see, for example, German Patents 1,213,98~ and 2,6~5,082). The SBR latex is preferably a conventional SBR latex, in other words, it is not carboxylated.
Usually such SB~ latex is produced by an emulsion polymerization in the presence of a conventional fatty acid or resin acid soap as an emulsifier. The SBR normally contains 15 to 35, preferably 20 to 30 % by wei.ght of styxene units.
The mixture of the latices~ after concentration have a viscosity of not more than 2~500, preferabl~ not more than 2,000 mPa s when measured in a Brookfield viscometer (Spindle III~ at 30 rpm and at 20 C) at a solid content of ~8 % by weight.
The thus concentrated mixture of the latices may be used as a reinforced elastomer component of a heat-vulcanizable composition for the production of late~ foam. The reinforced elastomer component is mixed with a vulcanizing agent and i:E
~ 23~3-305 necessary other conventional aclditives.
The vulcanizing agents are to be understood as meaning vulcanizing agents used in conventional vulcanization systems. A
preferred vulcanization system contains sulfur in combination with the usual accelerators. The amount of vulcanizing agent depends on the other mixture components and can be readily determined by simple orientation experiments.
Conventional additi~es are, for example, fat soaps and resin soaps (they can be present in the reinforced elastomer com-ponent in an amount sufficient for further processing of the vul-canizable composition), antiaging and light-protection agents, thickeners, e.g. carboxymethylcellulose, and fillers, such as, for example, chalk, kaolin and amylose (starch).
The invention will be explained by means of the examples set forth below. In these examples/ parts (p) mean parts by weight and percent (~) means weight percentO
The comparati.ve examples not in accordance with the in~ention are denoted by capital lettersO
The viscosities of the reinforced. elastomer components were determined in a Brookfield viscometer (spindle III, 30 rpm.
20C) ~2~ 3~
Productioll of Reinforcing Latices 1 and A-C
______ ~________~_ _______ _______ ________ Example_l (Styrene/Butadiene Graft Copolymer Latex of Xnvention) In a polymerization rea~tor, an emulsion of ~4 p fully demineralized water~ 0O2 p potassium oleate ~solid~
present as a 17% strength aqueous solution~, 0.1 p potas-sium carbonate, 0.015 p tetrasodium salt of ethylene-diaminetetraactic acid, 10 p styrene and 0.15 p a~onium persulfate was heated to 70 C during a period of 1-2 ho~rs.
During this step, a polystyrene nucleating latex ~as obtainad having an average particle diameter of 40 nm.
At 75 C, the followin~ streams were added ~o this batchO
~ 1) A mixture of 19 p fully demineralized water and 4 p potass.ium oleate (solidr present as a 17 strength aqueous solution); feeding period: S hours (constant flow velocity3.
(23 A solution of 1.35 p ammonium persulfate in 6 p ully demineralized water; feeding periodo 6 hours (constant flow velocity)~
(33 A mixture of 45 p styxene/1,3-butadiene (weight ratio: 89/11) and 0O06 p tert-dodecyl mercaptan, feeding period: 2.5 hours (constant flow velocity~.
(4~ A mixture of 45 p styrene/1~3-butadiene ~wei~ht ratio: 67/33) and 0.09 p tert-dodecyl mercaptan;
feeding period: 2.5 hours ~constant flow velocity3~
9;~
Feeding of streams (1) - (3) was begun simulta-neously. After 2.5 hours ~end of the first grafting stage), stream (41 was commenced~
The styrene/butadiene graft copolymer latex ob-tained after termination of the second grafting stage had a solids content of about 50% and an average particle dia~
meter of 220 nm.
Example A ~Styrene/Butadiene Graft Copolymer Latexl This example corresponds to Example 1 regarding the weight ratio of the monomers utiliæed in total ~styrene~1,3-butadiene = 80/20~ and with respect to the remaining production parameters; however, streams ~33 and (4) were replaced by the following stream:
(3~ A mixture of 90 p styrene/1,3-butadiene (weight ratio: 70/20) and 0.15 p tert-dodecyl mercaptan;
fee~ding period: 5 hours (constant flow velocity).
Feeding of streams ~ (31 was commenced simultaneously.
The styrene/butadiene graft copolymer latex obtained after termination of the grafting stage had a solids content of about 50% and an average particle diameter of 200 nm.
~26~3~
le B (Styrene/Butadiene Graft Copol~mer Latex~
This example corresponds to Example l; however~
stream ~4) was replaced by the followiny stream:
(4) A ~ixtur0 of 45 p styrene/1,3-butadiene (weight ratio 72/28) and 0.09 p tert-dodecyl mercaptan;
feeding per.iod: 205 hours ~constant flow velocity).
The styrene/butadiene graft copolymer latex produced after termination of the second grafting stage exhibited a solids content of about 50~ and an avexage particle diameter of ~10 nm~
Example C (Polystyrene La~ex) This example corresponds ~o Example l; however~
streams (3) and (4) were replaced by the following stream~
(3~ A mixture of 90 p styrene and 0O15 p ter~-dodecyl mercaptan; feeding period: 5 hours (constant flow ve~locity).
Feeding of streams (1) - (3) was commenced simultaneous].y.
The polystyrelle latex obtained after poly~
merization was finished had a solids content of about 50 and a~ average particle diameter of 200 nm.
Production of SBR Latex __ __._. ___________ __ The latex was prepared co.nventionally by reclox polymerization with the following formulati.on:
120 p Eully demineralized water 2.7 p potassium oleate (calculated as 100~ strength3 0.5 p of a condensation product from formaldehyde and naphthalenesulfonic acid 0.29 p potassium chloride 31 p styreIIe 69 p 1~3~butadien~
After a 65% conversion of the monomers, poly-merization was stopped. The resultant SBR latex was subjected to the steps indicated in German Patent 1,213,984 for agglomeration o:E the elastomer particles.
The average particle diameter was thereafter 240 nm.
The residual monomers were separated conventionally.
The~polymer contained 26~ repeating units obtained by polymerization of styrene (IR analysis~
Prepaxation of Reinforced Elastomer Components 1 and A-C
The SBR ].atex was mixed respectively with one of reinforcing latices 1 and A-C (solicls: 20 p phr~O
The thus-obtained mixture of latices was concentrated respectively to a solids content of 70~.
With a solids content ~f 68~, -the re.inforced elastomer components had the following viscosities:
l : 1,400 mPa's; A . 1,200 mPa-s;
B : 1,300 mPa-s; and C : 1,350 mPa-s.
Production of Vulcanizable Compositions l and A-C
and Latex Foams ~Test Specimens~ l and A-C
The vulcaniza~le composition~ were produced according to the following formulation (solids~O
lO0 p of one of the reinforced elastomer comp~
nen~s 1 and A-C
0.5 p potassium oleate ~added a~ a 17% stren~th aqueous solution) 0.25 p carboxymethylcellulose (added as a ~.5%
strength aqueous solu~tion) Prior to expansion~ the vulcanizable compositions were finished up by the addition of a 50% strength aqueous dispersion of the following vulcanizing syst~m (solids~:
2 p sulfur l p zinc diethyldithiocarbamate 1 p zirlc 2-mercaptobenzothiazole l p diphenylguanidine 3 p zinc oxide 0.5 p potassium oleate ~added as a 17~ strength aqueous solution) l p antîoxidant ~6~
By means of a whisked-foam producing machine, ~ir was whipped into the vulcanizable compositions. The resultant wet foams (foam density: about 130 g/l) were respectively combined with 2 p sodium silicofluoride~ pres-ent as a 25~ strength aqueous solution, and poured intoheatable molds. By gelling in the heating-up phase and subsequent vuleanizirlg at 100 C/30 min, the latex foams 1 and A-C were obtained. They were washed with water, dried at 75 C/16 h (foam density: 100 g/l), and characterized as indicated in the table below.
~2~
, ~ g ~
~ o o o I ~ ~ Z m I o o ~ N I U~
O
X
Lr) I I O a) I ~ I o o o Lr) I ~ .~J
o o o L~
dP æ I I
V~ 0 ~ I ' E~ Y ~
Ln.n ~ o S:
O ~ o I O
I a~ I o o o o I s:~ ~
X I ~ ~-- H
~ , ~ I I o 3 0 0 1 '~- '- J
M I. ~ h ~ I I r rl i` U~ I I h h ~H I I ts~t~
U Ig I d S I I ~ I~ I ' ~ ~
rl ~ n ,~ o ~ ) o ¦ h ~3 0 I
~ I O ~ 0 O I I ~ ~
~ L~
m m ~?
: i -- 1 5 --~ `
Tes~ specimens A and B show unsatisfactory values for compression set. Test specimen C has inadequat~ data for tensile strength and for elongation at break.
Claims (7)
- THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
l. A latex comprising styrene/butadiene graft copolymer particles which have an average particle diameter of 120 to 300 nm and are dispersed in the latex;
said graft copolymer particles consisting of [A] 35 to 65% by weight of a hard core having a comparatively high glass transition temperature and [B] 35 to 65% by weight of a soft shell having a comparatively low glass transition temperature, wherein the weight percentage is based on the total weight of the graft copolymer;
said hard core [A] being composed of a graft substrate which consists of an intermediate graft copolymer which is obtained in a two stage polymerization and comprises 1 to 20% by weight based on the final graft copolymer of a polystyrene nucleus and a copolymer grafted thereon consisting of 86 to 95% by weight of styrene units and 5 to 14% by weight of 1,3-butadiene units;
and said soft shell [B] being composed of a copolymer grafted on the graft substrate and consisting of 62 to 70% by weight of styrene units and 30 to 38% by weight of 1,3-butadiene units. - 2. A latex according to claim 1, wherein said graft copolymer particles consist of 45 to 60% by weight of the hard core [A] and 40 to 55% by weight of the soft shell [B].
- 3. A latex according to claim 1, wherein the graft substrate [A] consists of an intermediate graft copolymer which is obtained in a two stage polymerization and comprises 1 to 20% by weight based on the final graft copolymer of a polystyrene nucleus and a copolymer grafted thereon consisting of 87 to 93% by weight of styrene units and 7 to 13% by weight of 1,3-butadiene units; and said copolymer [B] consists of 65 to 63% by weight of styrene units and 31 to 35% by weight of 1,3-butadiene units.
- 4. A latex according to claim 1, 2 or 3, wherein said graft copolymer particles have an average particle diameter of 150 to 250 nm.
- 5. A process for producing the latex as defined in claim 1, which process comprises:
preparing the graft substrate, defined in claim 1 by a semicontinuous emulsion polymerization, and subjecting the graft substrate without isolation to a semicontinuous emulsion polymerization with styrene and 1,3-butadiene, wherein the process is carried out in the presence of 1 to 6% by weight of a fatty acid or resin acid soap as an emulsifier and not more than 0.3% by weight of a molecular weight regulator, the weight percentages being based on the total monomer and the grafting stages are carried out with intensive agitation while feeding the emulsifier so as to avoid formation of new particles. - 6. A process according to claim 5, wherein the amount of the emulsifier is 3 to 5% by weight and the amount of the molecular weight regulator is not more than 0.2% by weight.
- 7. A process according to claim 5 or 6, wherein the graft substrate is an intermediate graft copolymer which is prepared by a process comprising first and second stages, the first stage being an emulsion polymerization of styrene to product a polystyrene nucleous latex with an amount of 1 to 20 % by weight of solids based on the final graft copolymer and the second stage being a semicontinuous emulsion polymerization of styrene and 1,3-butadiene onto the polystyrene nucleus, wherein the second stage is carried out with intensive agitation while feeding the emulsifier so as to avoid formation of new particles.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19843447585 DE3447585A1 (en) | 1984-12-28 | 1984-12-28 | STYROL / BUTADIENE-GROPFCOPOLYMERISATE LATEX AND THIS CONTAINING AS A REINFORCING LATEX, WHICH CAN BE VULCANIZED IN THE HEAT FOR THE PRODUCTION OF LATEX FOAM |
| DEP3447585.0 | 1984-12-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1266934A true CA1266934A (en) | 1990-03-20 |
Family
ID=6254000
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000498572A Expired - Lifetime CA1266934A (en) | 1984-12-28 | 1985-12-24 | Styrene/butadiene graft copolymer latex and heat- vulcanizable composition, containing the latter as reinforcing latex, for the production of latex foam |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0187905B1 (en) |
| AT (1) | ATE54321T1 (en) |
| CA (1) | CA1266934A (en) |
| DE (2) | DE3447585A1 (en) |
| DK (1) | DK168446B1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10063160A1 (en) | 2000-12-18 | 2002-06-20 | Basf Ag | Aqueous polymer dispersion, used for production of latex foam and foam articles e.g. carpet backing, contains styrene-butadiene rubber particles and reinforcing polymer with hard and soft phases based on the same monomers |
| US20060052513A1 (en) | 2004-09-09 | 2006-03-09 | Soren Butz | Polymer latex suitable for the preparation of dip-molded articles |
| US8158691B2 (en) | 2005-04-04 | 2012-04-17 | Polymer Latex Gmbh & Co. Kg | Aqueous reinforced rubber dispersions and their use for making latex foams |
| US8222362B2 (en) | 2006-08-10 | 2012-07-17 | Polymerlatex Gmbh | Latex with reduced odor |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1056364B (en) * | 1956-06-09 | 1959-04-30 | Huels Chemische Werke Ag | Process for the production of articles from foam rubber |
| US3917749A (en) * | 1973-12-14 | 1975-11-04 | Goodyear Tire & Rubber | Resinous butadiene/styrene reinforcing copolymers |
| DE2607220C3 (en) * | 1976-02-23 | 1980-08-14 | Chemische Werke Huels Ag, 4370 Marl | Process for the preparation of aqueous copolymer dispersions |
| US4307134A (en) * | 1980-12-22 | 1981-12-22 | Atlantic Richfield Company | Process for producing plasticized elastomer-styrene coated beads |
| US4333969A (en) * | 1980-12-23 | 1982-06-08 | Atlantic Richfield Company | Process for producing styrenic polymer beads of preferred bead size |
-
1984
- 1984-12-28 DE DE19843447585 patent/DE3447585A1/en not_active Withdrawn
-
1985
- 1985-10-26 EP EP85113654A patent/EP0187905B1/en not_active Expired - Lifetime
- 1985-10-26 AT AT85113654T patent/ATE54321T1/en not_active IP Right Cessation
- 1985-10-26 DE DE8585113654T patent/DE3578565D1/en not_active Expired - Lifetime
- 1985-12-20 DK DK598485A patent/DK168446B1/en not_active IP Right Cessation
- 1985-12-24 CA CA000498572A patent/CA1266934A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| ATE54321T1 (en) | 1990-07-15 |
| DK598485D0 (en) | 1985-12-20 |
| EP0187905A3 (en) | 1987-07-29 |
| DK168446B1 (en) | 1994-03-28 |
| EP0187905A2 (en) | 1986-07-23 |
| DE3447585A1 (en) | 1986-07-10 |
| DK598485A (en) | 1986-06-29 |
| DE3578565D1 (en) | 1990-08-09 |
| EP0187905B1 (en) | 1990-07-04 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0077038B2 (en) | Process for producing impact resistant resins | |
| CA1194634A (en) | Particle agglomeration in rubber latices | |
| US4098734A (en) | Polymeric alloy composition | |
| CA1307865C (en) | Rubber-reinforced monovinylidene aromatic polymer resins and a methodfor their preparation | |
| CN105778001A (en) | Method for preparing carboxyl nitrile rubber by emulsion polymerization | |
| CA1106522A (en) | Combined emulsion and suspension process for producing graft abs bead-like particles | |
| US4785051A (en) | Rubber-modified monovinylidene aromatic polymer compositions | |
| CA1266934A (en) | Styrene/butadiene graft copolymer latex and heat- vulcanizable composition, containing the latter as reinforcing latex, for the production of latex foam | |
| EP0722974B1 (en) | Expandable rubber-modified styrene resin beads, expanded beads thereof, and expanded molded articles obtained therefrom | |
| US3403125A (en) | Method of concentrating aqueous latices of conjugated diolefinacrylonitrile copolymers | |
| EP0902047B1 (en) | Expandable rubber-modified styrene resin composition | |
| KR20000055262A (en) | Method for preparing thermoplastic resin with good impact resistance and natural color property | |
| US5925704A (en) | Reinforced rubber dispersions, their preparation and use | |
| US5187221A (en) | Styrene/butadiene graft copolymer latex and heat-vulcanizable composition, containing the latter as reinforcing latex, for the production of latex foam | |
| US4151128A (en) | Graft copolymers by suspension process following emulsion | |
| US6080803A (en) | Preparing coarse polymer dispersions | |
| EP0620236B1 (en) | Process for producing high impact polystyrene | |
| KR100455101B1 (en) | Method of Preparing SAN-Grafted Copolymer Resin with Excellent Appearance and Whiteness | |
| CA1075398A (en) | Manufacture of polyurethane compositions | |
| KR20020047092A (en) | Graft copolymer composition and vinyl chloride resin composition containing the same | |
| KR100188529B1 (en) | The preparation of thermoplastic resin composition having high glossness and high impact strength at low temperature | |
| US3465066A (en) | Process for the production of shock resisting polymers | |
| US3992484A (en) | Process for preparing high-impact vinyl aromatic polymers | |
| KR100567387B1 (en) | Thermoplastic Resin Composition with Improved Impact Strength and Brightness And Method of Preparing The Same | |
| CA2256030A1 (en) | Preparing polymer dispersion foams |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |