CA1040800A - Process for the preparation of expandable styrene polymer particles - Google Patents
Process for the preparation of expandable styrene polymer particlesInfo
- Publication number
- CA1040800A CA1040800A CA227,921A CA227921A CA1040800A CA 1040800 A CA1040800 A CA 1040800A CA 227921 A CA227921 A CA 227921A CA 1040800 A CA1040800 A CA 1040800A
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- Canada
- Prior art keywords
- polymer particles
- particles
- styrene polymer
- styrene
- expanding agent
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-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/16—Making expandable particles
- C08J9/18—Making expandable particles by impregnating polymer particles with the blowing agent
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2325/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring; Derivatives of such polymers
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A process for preparing expandable styrene polymer par-ticles by using calcium hydroxide as a suspending agent to pre-vent agglomeration of styrene polymer particles during impregna-tion with an expanding agent. The process comprises preparing expandable styrene polymer particles from styrene polymer par-ticles in water, wherein the expanding agent, which does not dissolve styrene polymer particles but slightly swells the par-ticles, and has a boiling point lower than the softening point of the particles, is added in the presence of the suspending agent the particles being impregnated thereby.
A process for preparing expandable styrene polymer par-ticles by using calcium hydroxide as a suspending agent to pre-vent agglomeration of styrene polymer particles during impregna-tion with an expanding agent. The process comprises preparing expandable styrene polymer particles from styrene polymer par-ticles in water, wherein the expanding agent, which does not dissolve styrene polymer particles but slightly swells the par-ticles, and has a boiling point lower than the softening point of the particles, is added in the presence of the suspending agent the particles being impregnated thereby.
Description
104~8()0 This invention relates to a process for the preparation of expandable styrene polymer particles.
Expandable styrene polymer particles are conventionally prepared by means of a process wherein styrene polymer particles are dispersed in water to form a suspension, and an expanding agent is then added to impregnate the particles: such a process is disclosed in U. S. Patent No. 2,893,963, issued July 7, 1959, W. J. Cleland et al and U. S. Patent No. 2,950,261, issued August 23, 1960, K. Buchholz et al. In this prior process there is a tendency of the particles, to agglomerate or stick together to form large clumps, during the impregnation; this results be-cause of the solvent action of the expanding agent during the impregnation of the polymer particles with the expanding agent.
In order to prevent agglomeration of the polymer par-ticles during the step of impregnation, suspending agents are generally used. As the suspending agents, there can be mentioned by way of example, the following compounds which are well known, partially saponified polyvinylalcohol, polyacrylate, polymeth-acrylate, polyvinylpyrrolidone, carboxymethyl cellulose, ethyl cellulose, methyl cellulose, sodium alginate which are water-soluble organic compounds having protective colloidal properties.
The above compounds are generally used together with surface active agents or sodium pyrophosphate, for example, in order to increase their suspension activity.
There is a tendency, however, to produce agglomerated particles when using the above-described water-soluble organic compounds as suspending agents at a high temperature, and it is necessary to carefully add the expanding agent in parts or a little at a time continuously when using an expanding agent which is in liquid form under ordinary conditions, for example, room temperature and atmospheric pressure; this applies, for example, to the use of n~pentane as the suspending agent. Such restric-tions in the step of impregnation are disadvantageous, since they - 1 - ~
, . ~
cause low productivity. Furthermore, environmental problems occur, since it is very difficult to remove the waste water after impregnation.
Suspending agents are disclosed in U. S. Patent No. t
Expandable styrene polymer particles are conventionally prepared by means of a process wherein styrene polymer particles are dispersed in water to form a suspension, and an expanding agent is then added to impregnate the particles: such a process is disclosed in U. S. Patent No. 2,893,963, issued July 7, 1959, W. J. Cleland et al and U. S. Patent No. 2,950,261, issued August 23, 1960, K. Buchholz et al. In this prior process there is a tendency of the particles, to agglomerate or stick together to form large clumps, during the impregnation; this results be-cause of the solvent action of the expanding agent during the impregnation of the polymer particles with the expanding agent.
In order to prevent agglomeration of the polymer par-ticles during the step of impregnation, suspending agents are generally used. As the suspending agents, there can be mentioned by way of example, the following compounds which are well known, partially saponified polyvinylalcohol, polyacrylate, polymeth-acrylate, polyvinylpyrrolidone, carboxymethyl cellulose, ethyl cellulose, methyl cellulose, sodium alginate which are water-soluble organic compounds having protective colloidal properties.
The above compounds are generally used together with surface active agents or sodium pyrophosphate, for example, in order to increase their suspension activity.
There is a tendency, however, to produce agglomerated particles when using the above-described water-soluble organic compounds as suspending agents at a high temperature, and it is necessary to carefully add the expanding agent in parts or a little at a time continuously when using an expanding agent which is in liquid form under ordinary conditions, for example, room temperature and atmospheric pressure; this applies, for example, to the use of n~pentane as the suspending agent. Such restric-tions in the step of impregnation are disadvantageous, since they - 1 - ~
, . ~
cause low productivity. Furthermore, environmental problems occur, since it is very difficult to remove the waste water after impregnation.
Suspending agents are disclosed in U. S. Patent No. t
2,983,692, issued May 9, 1961, Koppers Company, Inc., and U. K.
Patent No. 1,202,833: for example, slightly water-soluble, fine powders of inorganic substances such as tertiary calcium phos-phate, magnesium pyrophosphate, calcium carbonate, calcium sili-cate and bentonite, metal salts of an aliphatic acid such as calcium stearate and zinc stearate; and organic fine powders such as the bis-amide of an aliphatic acid, for example, ethyl- -ene-bis-stearoamide. However, the above-mentioned suspending agents are not economical, since in each case they must be used in relatively large quantities, of not less than 1% by weight of the styrene polymer particles, when used alone, in order to prevent agglomeration of the polymer particles caused by the expanding agent and/or softening agent.
Therefore, a method has been generally adopted of using the fine powders in combination with a surface active agent in order to increase the suspension activity. For example, U. S.
Patent No. 2,687,408, U. S. Patent No. 2,715,118 and U. S. Patent No. 2,983,692 show that good results were obtained by using an-ionic surface active agents with inorganic fine powders. Espec-ially stable suspension activity was obtained by using smaller ;
amounts of a suspending agent consisting of phosphate or pyro-phosphate, such as tertiary calcium phosphate, hydroxyapatite and magnesium pyrophosphate in combination with a small quantity of sodium dodecylbenzenesulfonate or sodium laurylalcohol-sulfate ~
ester. When using organic fine powders such as calcium stearate ~- -and ethylene-bis-amide, not only may anionic surface active agents be used but also nonionic and amphoteric surface active agents may be used in order to increase the suspension activity. How-. . , , , ., :,, .
ever, such suspending agents are generally not good agents.
Surface active agents have been used in combination with slightly water-soluble, fine powders as suspending agents in order to increase the suspension activity. However, it is very difficult to recover and/or release the expanding agent after the impregnation step, due to the vigorous foaming caused by the remaining expanding agent when using a surface active agent and an expanding agent such as propane or butane. It is necessary, therefore, to use an anti-foam agent in order to re-duce the amount of foam. It is also difficult to completely re-move the waste water containing the surface active agent by ordinary equipment used for treating waste water.
Inorganic compounds including phosphorus compound, such as phosphate or pyrophosphate, are nutritive substances when dis-charged into a river or lake and such discharging will be limited by means of the present invention to protect the environment in the future.
It has now been found that good suspension stability ~ ' is obtained by using a small amount of calcium hydroxide as the suspending agent, without the need of using it in combination with a surface active agent.
Expandable styrene polymer particles are produced hav-ing excellent suspension stability by using calcium hydroxide as a suspending agent. The process comprises the steps of dispers-ing styrene polymer particles in water and adding thereto and in the presence of a suspending agent an expanding agent which does not dissolve the particles but slightly swells the particles, and has a boiling point lower than the softening point of the polymer particles and is gaseous or liquid under ordinary condi-tions.
The present invention thus provides a process for the production of expandable styrene polymer particles which comprises
Patent No. 1,202,833: for example, slightly water-soluble, fine powders of inorganic substances such as tertiary calcium phos-phate, magnesium pyrophosphate, calcium carbonate, calcium sili-cate and bentonite, metal salts of an aliphatic acid such as calcium stearate and zinc stearate; and organic fine powders such as the bis-amide of an aliphatic acid, for example, ethyl- -ene-bis-stearoamide. However, the above-mentioned suspending agents are not economical, since in each case they must be used in relatively large quantities, of not less than 1% by weight of the styrene polymer particles, when used alone, in order to prevent agglomeration of the polymer particles caused by the expanding agent and/or softening agent.
Therefore, a method has been generally adopted of using the fine powders in combination with a surface active agent in order to increase the suspension activity. For example, U. S.
Patent No. 2,687,408, U. S. Patent No. 2,715,118 and U. S. Patent No. 2,983,692 show that good results were obtained by using an-ionic surface active agents with inorganic fine powders. Espec-ially stable suspension activity was obtained by using smaller ;
amounts of a suspending agent consisting of phosphate or pyro-phosphate, such as tertiary calcium phosphate, hydroxyapatite and magnesium pyrophosphate in combination with a small quantity of sodium dodecylbenzenesulfonate or sodium laurylalcohol-sulfate ~
ester. When using organic fine powders such as calcium stearate ~- -and ethylene-bis-amide, not only may anionic surface active agents be used but also nonionic and amphoteric surface active agents may be used in order to increase the suspension activity. How-. . , , , ., :,, .
ever, such suspending agents are generally not good agents.
Surface active agents have been used in combination with slightly water-soluble, fine powders as suspending agents in order to increase the suspension activity. However, it is very difficult to recover and/or release the expanding agent after the impregnation step, due to the vigorous foaming caused by the remaining expanding agent when using a surface active agent and an expanding agent such as propane or butane. It is necessary, therefore, to use an anti-foam agent in order to re-duce the amount of foam. It is also difficult to completely re-move the waste water containing the surface active agent by ordinary equipment used for treating waste water.
Inorganic compounds including phosphorus compound, such as phosphate or pyrophosphate, are nutritive substances when dis-charged into a river or lake and such discharging will be limited by means of the present invention to protect the environment in the future.
It has now been found that good suspension stability ~ ' is obtained by using a small amount of calcium hydroxide as the suspending agent, without the need of using it in combination with a surface active agent.
Expandable styrene polymer particles are produced hav-ing excellent suspension stability by using calcium hydroxide as a suspending agent. The process comprises the steps of dispers-ing styrene polymer particles in water and adding thereto and in the presence of a suspending agent an expanding agent which does not dissolve the particles but slightly swells the particles, and has a boiling point lower than the softening point of the polymer particles and is gaseous or liquid under ordinary condi-tions.
The present invention thus provides a process for the production of expandable styrene polymer particles which comprises
- 3 -using calcium hydroxide as the suspending agent in a process which comprises dispersing styrene polymer particles in water and adding thereto an expanding agent.
According to the invention there is provided in a process for the preparation of expandable styrene polymer particles comprising impregnating said particles with an expand-ing agent, the improvement which comprises employing in the process calcium hydroxide as a suspending agent, the calcium hydroxide being used in an amount of about 0.3 to about 1.5 weight p~rcent of the styrene polymer particles. It is suffi-cient to use only calcium hydroxide as the suspending agent.
In the step of removing or releasing remaining expand-ing agent after impregnation of the styrene polymer particles, the forming of foam is not observed in the present invention, while heretofore vigorous foaming was observed when surface active agents and/or water-soluble organic compounds were used. ,-The process of the present invention, therefore, is a superior process from a commercial point of view. The process of the present invention provides advantages in the treatment of waste water from the process, since calcium hydroxide is readily neutra-lized with hydrochloric acid to produce water-soluble calcium chloride which is easily removed from the system. Therefore, the procedure for treating waste water is less complicated in compari-son with procedures using surface active agents and/or water-soluble organic compounds having protective colloidal properties.
Calcium hydroxide used in the present invention may be ~ -that which is currently available on the market. Fine powders passing a screen having a 325 mesh (44 ~ sieve mesh, ASTM) are especially preferable. Generally, the amount of calcium hydrox-ide to be used is in the range of from about 0.3 to about 1.5 weight % based on the polymer particles. The amount of calcium hydroxide, however, may be varied depending on the size of the polymer particles to be used, ratio of polymer particles and ~ 4 ~
water, kind of expanding agent and other additives. Where cal-cium hydroxide is used in an amount of less than 0.3 weight %, there is a tendency to cause agglomeration of the polymer par-ticles, and where it is used in an amount of more than 1.5 weight %, it is not economical, since further advantages are not ob-tained.
It is possible to add an expanding agent in the re-action system over a wide range of temperatures, for example, from ordinary temperatures, or from 0C. to 125C, and suitably from 20C.to 125C.when calcium hydroxide is used as the sus-pending agent. In the case of using an expanding agent which is in liquid form at room temperature such as n-pentane, it is preferable to add such expanding agent at lower temperatures and increase to temperatures above 90C. to impregnate, since it is possible to obtain stable impregnation of the polymer particles without causing agglomeration. In the case of adding n-pentane in the reaction system at temperatures above 100C., it is possible to impregnate without causing agglomeration by feeding n-pentane incrementally according to the speed of absorption of !;
n-pentane into the polymer particles.
Steps for the production and operation of the present invention are very simplified as it is sufficient to use only calcium hydroxide as the suspending agent to obtain desirable results and it is not necessary to use calcium hydroxide in com-bination with organic or inorganic fine powders, surface active agents or organic compounds having protective colloidal proper-ties.
Styrene polymer particles which may be used in the present invention include: styrene polymer particles prepared by the polymerization of vinyl aromatic monomers including styrene, vinyltoluene, isopropylstyrene, alphamethylstyrene, nuclear methylstyrene, chlorostyrene and tertbutylstyrene, styrene 104~800 copolymer particles prepared by the copolymerization of a styrene monomer with monomers, including 1~ 3-butadiene, alkyl acrylates, for example, butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate,,alkyl methacrylates, for example, methyl methacrylate, ethyl methacrylate, butyl methacrylate and 2-ethylhexyl meth-acrylate), acrylonitrile, vinyl acetate, alpha-methylethylene, divinyl benzene, dimethyl maleate and diethyl maleate, wherein the styrene monomer is present in an amount of at least about 50% by weight based on the copolymex.
Styrene polymer particles can, of course, be produced by any of the known techniques, for example by suspension or mass polymerization, to obtain particles in the form of beads or pellets.
Such polymer particles have an average particle diameter of from 0.2 - 6 mm. ;
The polymer particles are dispersed in water, the amount of water being 0.7 - 5 times, and preferably 0.8 - 2 times the weight of the polymer particles employed.
The expanding agents employed in the present invention --include those (1) which do not dissolve the styrene polymer particles but slightly swell the polymer particles, (2) which --have a boiling point lower than the softening point of the above described polymer and (3) which are gaseous or liquid at ordinary conditions. Such expanding agents are disclosed in the specifica-tion of U. S. Patent No. 2,983,692 and U. S. Patent No. 2,893,963.
Examples of suitable expanding agents include aliphatic hydro-carbons having from 1 to 6 carbon atoms and preferably from 3 to -5 carbon atoms and a boiling point in the range of from -42 to -, 36C. Suitable expanding agents include propane, n-butane, iso-butane, n-pentane, neo-pentane, isopentane and n-hexane, cyclo-aliphatic hydrocarbons, for example, cyclopentane and cyclohexane, and halogenated hydrocarbons, for example methyl chloride, ethyl `~
~9 : . . . ,. , . ~
chloride, dichlorodifluoromethane, chlorodifluoromethane and trichlorofluoromethane. These expanding agents are irnpregnated into the polymer particles in an amount of from about 3% to about 15% by weight of the styrene polymer particles.
Flame retardants, for example, tris t2,3-dibromo-propyl) phosphate, tribromophenylallyl ether and hexabromocyclo-dodecane, and auxiliary agents for flame retardants, for example, organic peroxides may also be used in this invention, as well as dyestuffs, antistatic agents and other conventional additives.
The following examples are given to further illustrate the invention, and are not intended to limit the scope thereof.
2,200 g of water and 11 g of calcium hydroxide (sus-pending agent) were placed`into a 5.6 litre autoclave. The calcium hydroxide used in this example has the following analyti-cal data:
H2O content 0.3 %
Ignition Loss 24.51 %
SiO2 0.25 %
Fe2O3 and A12O3 0.18 %
CaO 74.36 %
MgO 0.50 %
C2 0.82 %
99.2% passes through a 300 mesh sieve (ASTM) To this mixture, 2,200 g of styrene polymer particles having a particle diameter size of 0.6 - 1.0 mm were added.
After the autoclave was made air-tight and the mixture was stirred at the speed of 320 rpm, 198 g of n-pentane as expanding agent were added under pressure and the temperature was increased to 110C. After impregnation for 3 hours at 110C., the mixture was cooled to 30C., removed from the reactor, neutralized with hydrochloric acid, washed with water and dried. The product of -expandable styrene polymer particles showed no agglomerated particles.
After ageing for 1 week, the polymer particles were pre-expanded by steam to particles having a density of 0.02 g/cc.
Good cellular shaped articles were obtained on the next day by molding the pre-expanded polymer particles in a mold with steam.
2,200 g of water and 11 g of calcium hydroxide, as described in Example 1, were added to a 5.6 litre autoclave and 2,200 g of a styrene-butyl acrylate copolymer, ~hich contains 98 parts of styrene and 2 parts of butyl acrylate and having a 1.0 - 0.6 mm diameter were also added. After the autoclave was , made air-tight and while the mixture was stirred at the speed of 320 rpm, the temperature was increased to 90C. While main- ~ -taining this temperature, 220 g of n-butane were added as expand-ing agent. After impregnation at the same temperature for S hours, the mixture was cooled to 30C., and the remaining gas was re-leased from a relief valve. Blocking of the valve by foam was not -observed in this case, and the remaining gas was easily released.
The expandable polymer particles were removed from the reactor and neutralized with hydrochloric acid, washed with water and dried. Expandable styrene-butyl acrylate copolymer particles - -having no agglomerated particles were obtained. -`
COMPARATIVE EXAMPLE A
- As a comparison with the results of Example 2, the pro-cedure of Example 2 was substantially repeated except that 11 g of magnesium pyrophosphate and 0.33 g of dodecylbenzene sulfonate were used instead of calcium hydroxide. After adding n-butane, the mixture was cooled to 30C. It was observed that most of the remaining expanding agent could not be released through the ' valve due to blocking of the valve caused by foaming of the mix-ture employed as the suspending agent.
,. : : . ., ....... ~ . . ..
: , j,;: .. :, . , , : :
104080~) 2,200 g of water and 11 g of calcium hydroxide as des-cribed in Example 1 were added to a 5.6 litre autoclave and 2,200 g of styrene polymer particles having a 1.0 - 0.6 mm diameter were also added. To this mixture, 27 g of tribromo-phenylallyl ether were added as a flame retardant agent while stirring at the speed of 320 rpm. After the autoclave was made air-tight, 176 g of n-pentane (expanding agent) were added at a temperature of 30C. The mixture was heated to 110C. over a period of 60 minutes and impregnated at the sam* temperature for
According to the invention there is provided in a process for the preparation of expandable styrene polymer particles comprising impregnating said particles with an expand-ing agent, the improvement which comprises employing in the process calcium hydroxide as a suspending agent, the calcium hydroxide being used in an amount of about 0.3 to about 1.5 weight p~rcent of the styrene polymer particles. It is suffi-cient to use only calcium hydroxide as the suspending agent.
In the step of removing or releasing remaining expand-ing agent after impregnation of the styrene polymer particles, the forming of foam is not observed in the present invention, while heretofore vigorous foaming was observed when surface active agents and/or water-soluble organic compounds were used. ,-The process of the present invention, therefore, is a superior process from a commercial point of view. The process of the present invention provides advantages in the treatment of waste water from the process, since calcium hydroxide is readily neutra-lized with hydrochloric acid to produce water-soluble calcium chloride which is easily removed from the system. Therefore, the procedure for treating waste water is less complicated in compari-son with procedures using surface active agents and/or water-soluble organic compounds having protective colloidal properties.
Calcium hydroxide used in the present invention may be ~ -that which is currently available on the market. Fine powders passing a screen having a 325 mesh (44 ~ sieve mesh, ASTM) are especially preferable. Generally, the amount of calcium hydrox-ide to be used is in the range of from about 0.3 to about 1.5 weight % based on the polymer particles. The amount of calcium hydroxide, however, may be varied depending on the size of the polymer particles to be used, ratio of polymer particles and ~ 4 ~
water, kind of expanding agent and other additives. Where cal-cium hydroxide is used in an amount of less than 0.3 weight %, there is a tendency to cause agglomeration of the polymer par-ticles, and where it is used in an amount of more than 1.5 weight %, it is not economical, since further advantages are not ob-tained.
It is possible to add an expanding agent in the re-action system over a wide range of temperatures, for example, from ordinary temperatures, or from 0C. to 125C, and suitably from 20C.to 125C.when calcium hydroxide is used as the sus-pending agent. In the case of using an expanding agent which is in liquid form at room temperature such as n-pentane, it is preferable to add such expanding agent at lower temperatures and increase to temperatures above 90C. to impregnate, since it is possible to obtain stable impregnation of the polymer particles without causing agglomeration. In the case of adding n-pentane in the reaction system at temperatures above 100C., it is possible to impregnate without causing agglomeration by feeding n-pentane incrementally according to the speed of absorption of !;
n-pentane into the polymer particles.
Steps for the production and operation of the present invention are very simplified as it is sufficient to use only calcium hydroxide as the suspending agent to obtain desirable results and it is not necessary to use calcium hydroxide in com-bination with organic or inorganic fine powders, surface active agents or organic compounds having protective colloidal proper-ties.
Styrene polymer particles which may be used in the present invention include: styrene polymer particles prepared by the polymerization of vinyl aromatic monomers including styrene, vinyltoluene, isopropylstyrene, alphamethylstyrene, nuclear methylstyrene, chlorostyrene and tertbutylstyrene, styrene 104~800 copolymer particles prepared by the copolymerization of a styrene monomer with monomers, including 1~ 3-butadiene, alkyl acrylates, for example, butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate,,alkyl methacrylates, for example, methyl methacrylate, ethyl methacrylate, butyl methacrylate and 2-ethylhexyl meth-acrylate), acrylonitrile, vinyl acetate, alpha-methylethylene, divinyl benzene, dimethyl maleate and diethyl maleate, wherein the styrene monomer is present in an amount of at least about 50% by weight based on the copolymex.
Styrene polymer particles can, of course, be produced by any of the known techniques, for example by suspension or mass polymerization, to obtain particles in the form of beads or pellets.
Such polymer particles have an average particle diameter of from 0.2 - 6 mm. ;
The polymer particles are dispersed in water, the amount of water being 0.7 - 5 times, and preferably 0.8 - 2 times the weight of the polymer particles employed.
The expanding agents employed in the present invention --include those (1) which do not dissolve the styrene polymer particles but slightly swell the polymer particles, (2) which --have a boiling point lower than the softening point of the above described polymer and (3) which are gaseous or liquid at ordinary conditions. Such expanding agents are disclosed in the specifica-tion of U. S. Patent No. 2,983,692 and U. S. Patent No. 2,893,963.
Examples of suitable expanding agents include aliphatic hydro-carbons having from 1 to 6 carbon atoms and preferably from 3 to -5 carbon atoms and a boiling point in the range of from -42 to -, 36C. Suitable expanding agents include propane, n-butane, iso-butane, n-pentane, neo-pentane, isopentane and n-hexane, cyclo-aliphatic hydrocarbons, for example, cyclopentane and cyclohexane, and halogenated hydrocarbons, for example methyl chloride, ethyl `~
~9 : . . . ,. , . ~
chloride, dichlorodifluoromethane, chlorodifluoromethane and trichlorofluoromethane. These expanding agents are irnpregnated into the polymer particles in an amount of from about 3% to about 15% by weight of the styrene polymer particles.
Flame retardants, for example, tris t2,3-dibromo-propyl) phosphate, tribromophenylallyl ether and hexabromocyclo-dodecane, and auxiliary agents for flame retardants, for example, organic peroxides may also be used in this invention, as well as dyestuffs, antistatic agents and other conventional additives.
The following examples are given to further illustrate the invention, and are not intended to limit the scope thereof.
2,200 g of water and 11 g of calcium hydroxide (sus-pending agent) were placed`into a 5.6 litre autoclave. The calcium hydroxide used in this example has the following analyti-cal data:
H2O content 0.3 %
Ignition Loss 24.51 %
SiO2 0.25 %
Fe2O3 and A12O3 0.18 %
CaO 74.36 %
MgO 0.50 %
C2 0.82 %
99.2% passes through a 300 mesh sieve (ASTM) To this mixture, 2,200 g of styrene polymer particles having a particle diameter size of 0.6 - 1.0 mm were added.
After the autoclave was made air-tight and the mixture was stirred at the speed of 320 rpm, 198 g of n-pentane as expanding agent were added under pressure and the temperature was increased to 110C. After impregnation for 3 hours at 110C., the mixture was cooled to 30C., removed from the reactor, neutralized with hydrochloric acid, washed with water and dried. The product of -expandable styrene polymer particles showed no agglomerated particles.
After ageing for 1 week, the polymer particles were pre-expanded by steam to particles having a density of 0.02 g/cc.
Good cellular shaped articles were obtained on the next day by molding the pre-expanded polymer particles in a mold with steam.
2,200 g of water and 11 g of calcium hydroxide, as described in Example 1, were added to a 5.6 litre autoclave and 2,200 g of a styrene-butyl acrylate copolymer, ~hich contains 98 parts of styrene and 2 parts of butyl acrylate and having a 1.0 - 0.6 mm diameter were also added. After the autoclave was , made air-tight and while the mixture was stirred at the speed of 320 rpm, the temperature was increased to 90C. While main- ~ -taining this temperature, 220 g of n-butane were added as expand-ing agent. After impregnation at the same temperature for S hours, the mixture was cooled to 30C., and the remaining gas was re-leased from a relief valve. Blocking of the valve by foam was not -observed in this case, and the remaining gas was easily released.
The expandable polymer particles were removed from the reactor and neutralized with hydrochloric acid, washed with water and dried. Expandable styrene-butyl acrylate copolymer particles - -having no agglomerated particles were obtained. -`
COMPARATIVE EXAMPLE A
- As a comparison with the results of Example 2, the pro-cedure of Example 2 was substantially repeated except that 11 g of magnesium pyrophosphate and 0.33 g of dodecylbenzene sulfonate were used instead of calcium hydroxide. After adding n-butane, the mixture was cooled to 30C. It was observed that most of the remaining expanding agent could not be released through the ' valve due to blocking of the valve caused by foaming of the mix-ture employed as the suspending agent.
,. : : . ., ....... ~ . . ..
: , j,;: .. :, . , , : :
104080~) 2,200 g of water and 11 g of calcium hydroxide as des-cribed in Example 1 were added to a 5.6 litre autoclave and 2,200 g of styrene polymer particles having a 1.0 - 0.6 mm diameter were also added. To this mixture, 27 g of tribromo-phenylallyl ether were added as a flame retardant agent while stirring at the speed of 320 rpm. After the autoclave was made air-tight, 176 g of n-pentane (expanding agent) were added at a temperature of 30C. The mixture was heated to 110C. over a period of 60 minutes and impregnated at the sam* temperature for
4 hours. After cooling to 30C., the mixture was removed from the reactor and neutralized with hydrochloric acid, washed with water and dried. Flame retardant expandable styrene polymer par-ticles were obtained. The obtained polymer particles showed no agglomerated particles.
2,200 g of water and 22 g of calcium hydroxide, as des-cribed in Example 1, were added to a 5.6 litre autoclave and 2,200 g of styrene polymer particles of 0.5 - 0. 3 mm diameter were also added. After the autoclave was made air-tight and the mixture was stirred at the speed of 320 rpm, 154 g of n-pentane (expanding agent) were added to the above mixture at 30C.
and the mixture was heated to 110C. over a period of 60 minutes.
After maintaining the mixture at the same temperature as the above for 30 minutes, the mixture was cooled to 30 C. and removed.
The resulting expandable polymer particles showed no agglomerated particles. From this example, it will be recognized that impregnation of polymer particles having a small size can be easily carried out by using 1 weight % of calcium hydroxide.
Expandable polymer particles were prepared by the pro-cess as described in Example 1 except that cross-linked stryene-_ g _ :: 10~()80V
divinylbenzene copolymer particles having a 1.0 - 0.6 mm diameter consisting of 99.98 parts of styrene and 0.02 parts of divinyl-benzene were used instead of styrene polymer particles. The resulting expandable copolymer particles showed no agglomerated particles.
In place of the particular polymer particles and ex-panding agents employed in the Examples, other polymer particles and expanding agents as hereinbefore described may be substituted therefore to obtain substantially the same results.
- 10 -.
: . . : .
'. ,~
. . .
2,200 g of water and 22 g of calcium hydroxide, as des-cribed in Example 1, were added to a 5.6 litre autoclave and 2,200 g of styrene polymer particles of 0.5 - 0. 3 mm diameter were also added. After the autoclave was made air-tight and the mixture was stirred at the speed of 320 rpm, 154 g of n-pentane (expanding agent) were added to the above mixture at 30C.
and the mixture was heated to 110C. over a period of 60 minutes.
After maintaining the mixture at the same temperature as the above for 30 minutes, the mixture was cooled to 30 C. and removed.
The resulting expandable polymer particles showed no agglomerated particles. From this example, it will be recognized that impregnation of polymer particles having a small size can be easily carried out by using 1 weight % of calcium hydroxide.
Expandable polymer particles were prepared by the pro-cess as described in Example 1 except that cross-linked stryene-_ g _ :: 10~()80V
divinylbenzene copolymer particles having a 1.0 - 0.6 mm diameter consisting of 99.98 parts of styrene and 0.02 parts of divinyl-benzene were used instead of styrene polymer particles. The resulting expandable copolymer particles showed no agglomerated particles.
In place of the particular polymer particles and ex-panding agents employed in the Examples, other polymer particles and expanding agents as hereinbefore described may be substituted therefore to obtain substantially the same results.
- 10 -.
: . . : .
'. ,~
. . .
Claims (11)
1. In a process for the preparation of expandable styrene polymer particles comprising impregnating said particles with an expanding agent, the improvement which comprises employing in the process calcium hydroxide as a suspending agent, said calcium hydroxide being used in an amount of about 0.3 to about 1.5 weight percent of the styrene polymer particles.
2. The process of Claim 1, wherein the styrene polymer particles are polymer particles prepared by the polymerization of a vinyl aromatic monomer selected from the group consisting of styrene, vinyltoluene, isopropylstyrene, alpha-methylstyrene, nuclear methylstyrene, chlorostyrene and tertiary-butylstyrene.
3. The process of Claim 1, wherein the styrene polymer particles are styrene copolymer particles prepared by the co-polymerization of a styrene monomer and a monomer selected from the group consisting of 1, 3-butadiene, alkyl acrylate, alkyl methacrylate, acrylonitrile, vinyl acetate, .alpha.-methylethylene, vinyl benzene and dialkyl maleate, wherein the styrene monomer is present in an amount of at least about 50% by weight of the copolymer.
4. The process of Claim 1, wherein the expanding agent is a hydrocarbon selected from the group consisting of propane, n-butane, isobutane, n-pentane, neo-pentane, isopentane, n-hexane, cyclopentane and cyclohexane.
5. The process of Claim 1, wherein the expanding agent is a halogenated hydrocarbon selected from the group consisting of methyl chloride, ethyl chloride, dichlorodifluoromethane, chlorodifluoromethane and trichlorofluoromethane.
6. The process of Claim 4, wherein said expanding agent is used in an amount from about 3 to about 15% by weight of the styrene polymer particles.
7. The process of claims 1, 5 or 6, wherein said calcium hydroxide is of a fine particle size passing a screen of 325 mesh.
8. The process of claims 1, 2 or 3, wherein said polymer particles have an average particle diameter of from 0.2 - 6 mm.
9. A process for the preparation of non-agglomerated ex-pandable styrene polymer particles comprising forming a suspension of styrene polymer particles in water, said particles having an average particle diameter of from 0.2 - 6 mm, said suspension containing at least about 0.3 weight % based on the polymer particles of finely powdered calcium hydroxide as a suspending agent, introducing a liquid or gaseous expanding agent into said suspension, allowing said expanding agent to impregnate said poly-mer particles and recovering non-agglomerated expandable styrene polymer particles; said expanding agent being a non-solvent and non-swelling agent for said polymer particles but only slightly swelling said polymer particles and having a boiling point lower than the softening point of the polymer particles.
10. A process according to Claim 9, wherein the polymer particles are suspended in an amount of water 0.7 to 5 times their own weight.
11. A process according to Claim 9 or 10, in which said expanding agent is an aliphatic hydrocarbon of 3 to 5 carbon atoms.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6333674A JPS553368B2 (en) | 1974-06-03 | 1974-06-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1040800A true CA1040800A (en) | 1978-10-17 |
Family
ID=13226285
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA227,921A Expired CA1040800A (en) | 1974-06-03 | 1975-05-28 | Process for the preparation of expandable styrene polymer particles |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS553368B2 (en) |
| BE (1) | BE829686A (en) |
| CA (1) | CA1040800A (en) |
| FR (1) | FR2273034B1 (en) |
| GB (1) | GB1494263A (en) |
| IT (1) | IT1038591B (en) |
| NL (1) | NL7504811A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5347480A (en) * | 1976-10-14 | 1978-04-27 | Kureha Chem Ind Co Ltd | Method for increasing density of coagulated particles |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5222781B2 (en) * | 1973-12-17 | 1977-06-20 |
-
1974
- 1974-06-03 JP JP6333674A patent/JPS553368B2/ja not_active Expired
-
1975
- 1975-04-23 NL NL7504811A patent/NL7504811A/en not_active Application Discontinuation
- 1975-05-20 FR FR7515650A patent/FR2273034B1/fr not_active Expired
- 1975-05-23 GB GB2300275A patent/GB1494263A/en not_active Expired
- 1975-05-28 CA CA227,921A patent/CA1040800A/en not_active Expired
- 1975-05-29 BE BE7000667A patent/BE829686A/en unknown
- 1975-05-30 IT IT2389475A patent/IT1038591B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| GB1494263A (en) | 1977-12-07 |
| DE2518963A1 (en) | 1975-12-04 |
| JPS50154366A (en) | 1975-12-12 |
| IT1038591B (en) | 1979-11-30 |
| DE2518963B2 (en) | 1977-04-21 |
| JPS553368B2 (en) | 1980-01-24 |
| FR2273034A1 (en) | 1975-12-26 |
| FR2273034B1 (en) | 1977-07-08 |
| NL7504811A (en) | 1975-12-05 |
| BE829686A (en) | 1975-09-15 |
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