CA1043950A - Process for preparing expandible particles of styrene-based polymers - Google Patents
Process for preparing expandible particles of styrene-based polymersInfo
- Publication number
- CA1043950A CA1043950A CA193,035A CA193035A CA1043950A CA 1043950 A CA1043950 A CA 1043950A CA 193035 A CA193035 A CA 193035A CA 1043950 A CA1043950 A CA 1043950A
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- Prior art keywords
- styrene
- particles
- expandible
- based polymer
- formula
- Prior art date
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Classifications
-
- 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
- C08J9/0014—Use of organic additives
- C08J9/0023—Use of organic additives containing oxygen
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/04—Oxygen-containing compounds
- C08K5/13—Phenols; Phenolates
-
- 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
- C08J2325/02—Homopolymers or copolymers of hydrocarbons
- C08J2325/04—Homopolymers or copolymers of styrene
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Emergency Medicine (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Polymerisation Methods In General (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
There is disclosed a process for the preparation of expandible particles of styrene-based polymers which are useful for the production of molded bodies, especially large blocks, having a uniform cellular structure, and with a particularly short time of residence in the mold.
There is disclosed a process for the preparation of expandible particles of styrene-based polymers which are useful for the production of molded bodies, especially large blocks, having a uniform cellular structure, and with a particularly short time of residence in the mold.
Description
3i'~
:
TH13 PP~IOR ART
,.' . ,'' It is known to obtain shaped bodies from expanded styrene-based polymers by molding fine particles of the polymers containing gaseous or liquid expanding agents in closed (not gas-tight) molds at a temperature .` exceeding the boiling point of the expanding agent and the softening point of the polymeric material.
According to the usual method, the polymer particles containing the expanding agent are first heated (pre-expanded) in either an open or closed vessel until the particles reach a pre-established apparent dcnsity ~
and then, after a certain ageing period, further expanded by heating (molding) ~ -`~,15 in a pressure-resistant mold which is not gas-tight. As a COnsequellCe of the heating in the mold, the particles sinter to a body having the shape of the mold. The molded body or object is allowed to cool in the mold for a period of time sufficient to avoid deformation thereof dùring or after removal from the mold.
~20 .
:. . ' . ' . :'' 1~?'1;~
To recluco the re~idenco time in the m~ld, it ha~ bcen ~u~eestcd to incorporate small amounts of organic halogenated compounds, and generally bronnine, chlorine or chloro-bromo derivatives in the styrene-- based polymer.
However, that practice is not completely free of drawbacks. In fact, while incorporation of the organic halogenated compounds suggested in the art in the starting styrene-based polymer resuIts in a reduction, and even a considerable reduction, in the residence time in the mold, it is difficult to obtain blocks of expanded polymers which exhibit the following compendium of desirable characteristics:
(a) short residence time in the mold;
(b) shrinkage of the block thickness < 1%;
. (c) (total) moisture content of the expandible particles 0. 3%;
~, (d) fine-cell homogeneous structure of the expanded block; and (e) absence of odors during the pre-expansion step.
i, . . ..
::' THE PRESENT INVENTION
._ . .. .. _ .' .
One object of this invention is to provide a process for preparin g expandible particles of polystyrene or styrene copolymers suitable for producing molded bodies having a cellular structure and high-quality characteristics, using organic halogenated compounds for reducing the :0 residence time in the mold, but which process is free of the drawbacks mentioned above.
` -2-.. -- ---- , __ .
3~
Thls and oth(!r obj~ct~ are attaincd by thc pre~lent process for preparing shaped bodies based on expanclccl styrene-based polymers which . ~ comprises, in the order given: polymerization of styrene or a mixture thereo~ with another monomer copolymeriæable therèwith: addition of an cxpanding a~ent, preferably during the polymeri~ation; pre-expansion of the expandible particles; ageing of the pre-expanded particles followed by molding of the aged particles in a pressure-resistant but not gas-tight mold, in which process, and in accordance with this invention, the polymerization is carried out in the presence of 0. 001 to 0. 5, preferably 0. 05 to 0. 2 parts0 per cent by weight of àn organic brominated compound having the general formulae I and/or II:
'' R" -- O ~ O-- R" " (I) S ¦¦ ~ O--R"' ¦
~Br)n (II) .- . In the formulae given, R' and R" represent the same or dlfferent lower alkyl radicals, preferably methyl and ethyl, and are optionally ` halogenated; R"' and R" " in formula ~I) represent the same or different hydrocarbon groups containing 1 to 8 carbon atoms, and which are partially or wholly halogenated, preferably with bromine; R"' in formula tII)is a hydrocarbon group containing from 1 to 8 carbon atoms and is partially or .~ wholly halogenated; and n i9 an integer`from 1 to 5, ~ . .
: - . . .
;. . . .
't'~
Surprisingly, we found that thc expandible polym~ric particlc~
prcpared according~ to the method of this invention, and ea~panded shaped bodies molded from them, in particular blocks, have all of the following characteristics contemporaneously:
(a) a short timc residence in the mold, generally equal to or less than 50% of the time required for cooling the blocks obtained from pre-expanded particles not containing the organic brominated additive of this invention;
(b) shrinkage of the block thickness < 1%;
(c) (total) moisture in the expandible particles below 0. 3% and `practically identical with that of the particles prepared in the absence of the organic brominated additive used in the . practice of this invention;
(d) fine-cell homogeneous structure of the expanded block; and (e) complete absence of acrid odors (vapors of bromine, of hydrobromic acid or of organic bromoderivatives, etc. ) during the pre-expansion step, The organic brominated compounds useful for achieving the objects of this invention may be selected from a wide range of organic brominated compounds having formulae I and/or II. .
Particularly good results are attained with organic brominated compounds having the general formula ~I) in which R' and R" are the same or different and are CH3 - or CX3 - groups in which X is a halogen such as fluorine, bromine or chlorine; and R"' and R"" are halogen-substituted alkyl groups of the type ~CH2(CHX)m ~ CH2 in which m is an integer from 1 to 3 and X i8 a halogen, preferably bromine, .L~34~
A pre8ently preferred compound of formula I i8 2, 2^bls~4(2, 3-dibromopropoxy3-3, 5-dibromophenyll propane:
`~: .
H2~ CH20 _~ C ~ o_CH2--CH--fH2 Br Br B CH3 r Br Br ' :
Similarly, particularly good results are obtained using compounds having general formula (II) in which R"' represents a halogen-substituted alkyl group of the type:
~CH2-(CHX)m ~ CH2X
in which m is an integer from 1 to 3 and X i5 a halogen, preferably bromine.
A presently preferred brominated compound of formula (II) is:
Br ~. ~ . ~ . .` '::
Br ~ O - CH2 - I H _ I H~
; 15 Compounds of formula (1) and of formula (II~ may be used in admixture.
The brom.inated compounds are usually added to the styrene or mixture thereof with at least one other polymerizable comonomer prior to the polymerization, optionally in admixture with the expanding agents.
The term "styrene-based polymer" a~ u~ed herein includes the homopolymer, polystyrene, as well as copolymers of styrene with other vinyl and/or vinylidene monomers which copolymers contain at least 50%
by weight of chemically combined styrene.
.A .
~` _5_ ",,,,, ,, ~
11)43U~?(`;
Examplcs oli suitable comonomers are alpha-methylstyrene, nuclearly halogenated styrenes, acrylonitrile, methacrylonitrile, esters of acrylic anc3/or methacrylic acid with alcohols containing from 1 to 8 carbon atoms, N-vinyl-compounds, such as vinylcarbazole. The class constituted by the styrene-based copolymers includes also the copolymers containing, besides styrene and, optionally, the aforesaid vinyl and/or vinylidene monomers, also small amounts of monomers containing two double bonds, such as, for instance, divinylbenzene.
The compounds used as expanding agents for the styrene-based polymers may be selected from a wide class of compounds the characteris~cs of which are known to those skilled in the art.
Particularly suitable for use in the present procèss are the aliphatic hydrocarbons, either individually or in proper mutual admixtures, and containing from 2 to 6 carbon atoms, such as propane, butane, pentane, hexane, cyclohexane and the like, and the halogenated derivatives of aliphatic hydrocarbons containing from 1 to 3 carbon atoms, such as e. g.
chlorofluoro-derivatives of methane, of ethane and of ethylene.
- Besides the expanding agents, the styrene-based polymers according to this invention may contain other additives, such as, for example, flame-extinguishing agents, organic and inorganic fillers, dyes, antistatic agents, anti-agglomerating agents to prevent the formation of crumbs during the pre-expansion, plasticizers and other analogous compounds.
` Polymerization of styrene, preerably in an aqueous suspension, admixture of the expanding agent, preferably during polymerization, pre-expansion of the expandible particles thus obtained, ageing and transformation of the pre-expanded and aged particles into shaped bodies, by molding in - closed molds, are carried out according to known techniclues such as are descril)ed in "Rigid Plastic Foams" by T. N. Ferrigno, Reinhold Publishing ~` - -6-, lf~4;~ S Sj ' I
Corp., New York, USA (1963), The following examples are given to illustrate the essential features of the present invention~ and are not intended to be limiting:
E XA M P LE I
5Various aqueous suspension polymerization tests were carried : `
out starting from mixture made up of:
Parts By weight monomeric styrene - lO0 .deionized water 100 10polymerization initiator (1) 0. 20 suspending agent (2) 0. 05 ` ` .
NaCl 0. 1 organic brominated compound ( 3) 0. 1 ~1) mixture of tert. -butylperoxide and tert. -butyl-perbenzoate;
:
TH13 PP~IOR ART
,.' . ,'' It is known to obtain shaped bodies from expanded styrene-based polymers by molding fine particles of the polymers containing gaseous or liquid expanding agents in closed (not gas-tight) molds at a temperature .` exceeding the boiling point of the expanding agent and the softening point of the polymeric material.
According to the usual method, the polymer particles containing the expanding agent are first heated (pre-expanded) in either an open or closed vessel until the particles reach a pre-established apparent dcnsity ~
and then, after a certain ageing period, further expanded by heating (molding) ~ -`~,15 in a pressure-resistant mold which is not gas-tight. As a COnsequellCe of the heating in the mold, the particles sinter to a body having the shape of the mold. The molded body or object is allowed to cool in the mold for a period of time sufficient to avoid deformation thereof dùring or after removal from the mold.
~20 .
:. . ' . ' . :'' 1~?'1;~
To recluco the re~idenco time in the m~ld, it ha~ bcen ~u~eestcd to incorporate small amounts of organic halogenated compounds, and generally bronnine, chlorine or chloro-bromo derivatives in the styrene-- based polymer.
However, that practice is not completely free of drawbacks. In fact, while incorporation of the organic halogenated compounds suggested in the art in the starting styrene-based polymer resuIts in a reduction, and even a considerable reduction, in the residence time in the mold, it is difficult to obtain blocks of expanded polymers which exhibit the following compendium of desirable characteristics:
(a) short residence time in the mold;
(b) shrinkage of the block thickness < 1%;
. (c) (total) moisture content of the expandible particles 0. 3%;
~, (d) fine-cell homogeneous structure of the expanded block; and (e) absence of odors during the pre-expansion step.
i, . . ..
::' THE PRESENT INVENTION
._ . .. .. _ .' .
One object of this invention is to provide a process for preparin g expandible particles of polystyrene or styrene copolymers suitable for producing molded bodies having a cellular structure and high-quality characteristics, using organic halogenated compounds for reducing the :0 residence time in the mold, but which process is free of the drawbacks mentioned above.
` -2-.. -- ---- , __ .
3~
Thls and oth(!r obj~ct~ are attaincd by thc pre~lent process for preparing shaped bodies based on expanclccl styrene-based polymers which . ~ comprises, in the order given: polymerization of styrene or a mixture thereo~ with another monomer copolymeriæable therèwith: addition of an cxpanding a~ent, preferably during the polymeri~ation; pre-expansion of the expandible particles; ageing of the pre-expanded particles followed by molding of the aged particles in a pressure-resistant but not gas-tight mold, in which process, and in accordance with this invention, the polymerization is carried out in the presence of 0. 001 to 0. 5, preferably 0. 05 to 0. 2 parts0 per cent by weight of àn organic brominated compound having the general formulae I and/or II:
'' R" -- O ~ O-- R" " (I) S ¦¦ ~ O--R"' ¦
~Br)n (II) .- . In the formulae given, R' and R" represent the same or dlfferent lower alkyl radicals, preferably methyl and ethyl, and are optionally ` halogenated; R"' and R" " in formula ~I) represent the same or different hydrocarbon groups containing 1 to 8 carbon atoms, and which are partially or wholly halogenated, preferably with bromine; R"' in formula tII)is a hydrocarbon group containing from 1 to 8 carbon atoms and is partially or .~ wholly halogenated; and n i9 an integer`from 1 to 5, ~ . .
: - . . .
;. . . .
't'~
Surprisingly, we found that thc expandible polym~ric particlc~
prcpared according~ to the method of this invention, and ea~panded shaped bodies molded from them, in particular blocks, have all of the following characteristics contemporaneously:
(a) a short timc residence in the mold, generally equal to or less than 50% of the time required for cooling the blocks obtained from pre-expanded particles not containing the organic brominated additive of this invention;
(b) shrinkage of the block thickness < 1%;
(c) (total) moisture in the expandible particles below 0. 3% and `practically identical with that of the particles prepared in the absence of the organic brominated additive used in the . practice of this invention;
(d) fine-cell homogeneous structure of the expanded block; and (e) complete absence of acrid odors (vapors of bromine, of hydrobromic acid or of organic bromoderivatives, etc. ) during the pre-expansion step, The organic brominated compounds useful for achieving the objects of this invention may be selected from a wide range of organic brominated compounds having formulae I and/or II. .
Particularly good results are attained with organic brominated compounds having the general formula ~I) in which R' and R" are the same or different and are CH3 - or CX3 - groups in which X is a halogen such as fluorine, bromine or chlorine; and R"' and R"" are halogen-substituted alkyl groups of the type ~CH2(CHX)m ~ CH2 in which m is an integer from 1 to 3 and X i8 a halogen, preferably bromine, .L~34~
A pre8ently preferred compound of formula I i8 2, 2^bls~4(2, 3-dibromopropoxy3-3, 5-dibromophenyll propane:
`~: .
H2~ CH20 _~ C ~ o_CH2--CH--fH2 Br Br B CH3 r Br Br ' :
Similarly, particularly good results are obtained using compounds having general formula (II) in which R"' represents a halogen-substituted alkyl group of the type:
~CH2-(CHX)m ~ CH2X
in which m is an integer from 1 to 3 and X i5 a halogen, preferably bromine.
A presently preferred brominated compound of formula (II) is:
Br ~. ~ . ~ . .` '::
Br ~ O - CH2 - I H _ I H~
; 15 Compounds of formula (1) and of formula (II~ may be used in admixture.
The brom.inated compounds are usually added to the styrene or mixture thereof with at least one other polymerizable comonomer prior to the polymerization, optionally in admixture with the expanding agents.
The term "styrene-based polymer" a~ u~ed herein includes the homopolymer, polystyrene, as well as copolymers of styrene with other vinyl and/or vinylidene monomers which copolymers contain at least 50%
by weight of chemically combined styrene.
.A .
~` _5_ ",,,,, ,, ~
11)43U~?(`;
Examplcs oli suitable comonomers are alpha-methylstyrene, nuclearly halogenated styrenes, acrylonitrile, methacrylonitrile, esters of acrylic anc3/or methacrylic acid with alcohols containing from 1 to 8 carbon atoms, N-vinyl-compounds, such as vinylcarbazole. The class constituted by the styrene-based copolymers includes also the copolymers containing, besides styrene and, optionally, the aforesaid vinyl and/or vinylidene monomers, also small amounts of monomers containing two double bonds, such as, for instance, divinylbenzene.
The compounds used as expanding agents for the styrene-based polymers may be selected from a wide class of compounds the characteris~cs of which are known to those skilled in the art.
Particularly suitable for use in the present procèss are the aliphatic hydrocarbons, either individually or in proper mutual admixtures, and containing from 2 to 6 carbon atoms, such as propane, butane, pentane, hexane, cyclohexane and the like, and the halogenated derivatives of aliphatic hydrocarbons containing from 1 to 3 carbon atoms, such as e. g.
chlorofluoro-derivatives of methane, of ethane and of ethylene.
- Besides the expanding agents, the styrene-based polymers according to this invention may contain other additives, such as, for example, flame-extinguishing agents, organic and inorganic fillers, dyes, antistatic agents, anti-agglomerating agents to prevent the formation of crumbs during the pre-expansion, plasticizers and other analogous compounds.
` Polymerization of styrene, preerably in an aqueous suspension, admixture of the expanding agent, preferably during polymerization, pre-expansion of the expandible particles thus obtained, ageing and transformation of the pre-expanded and aged particles into shaped bodies, by molding in - closed molds, are carried out according to known techniclues such as are descril)ed in "Rigid Plastic Foams" by T. N. Ferrigno, Reinhold Publishing ~` - -6-, lf~4;~ S Sj ' I
Corp., New York, USA (1963), The following examples are given to illustrate the essential features of the present invention~ and are not intended to be limiting:
E XA M P LE I
5Various aqueous suspension polymerization tests were carried : `
out starting from mixture made up of:
Parts By weight monomeric styrene - lO0 .deionized water 100 10polymerization initiator (1) 0. 20 suspending agent (2) 0. 05 ` ` .
NaCl 0. 1 organic brominated compound ( 3) 0. 1 ~1) mixture of tert. -butylperoxide and tert. -butyl-perbenzoate;
(2) acrylic acid/2-ethyl-hexylacrylate copolymer~ratio by weight = 8~/ll)
(3) different types of organic brominated compounds dissolved in styrene and having the following formulas:
20 ~ Br l H3 Br Br r Br ~H3 Br Br Br Br ¦¦ Ib) Br-~_ o - CH2 - CH- CH2 Br Br Br ~25 ; .
_7_ .
'''''-:`'' '' .
~ c) Br ~ O - CH2 - CH = CH2 ; ~3r (d) Br ~ O - CHa - CH2 - CH3 .
l Note: Compounds (a) and (b) are in accordance with this invention, while compounds (c) and (d) are given merely for comparative purposes.l I0 Polymerization was carried out at temperatures comprised between 100C and 140C for a total period of 20 hours.
During the polymerization step, 8 parts by weight of an expanding agent consisting of a mixture of n-pentane and isopentane (ratio by weight = ` ~ -70/30) were admixed to the aforesaid suspension.
After cooling to room temperature, filtering, washing with water, and drying at 35-40C for 7 hours, the polymer was subjected to screening in order to obtain expandible polystyrene particles having diameters comprising between 0. 9 and 1. 6 mm. Said particles contained about 6% by . weight of expanding a~;ent.
~:20 The expandible particles were admixed with a conventional non-a~glomerating agent in an amount equal to 0.15% by weight. The admixing wa~ carried out in a SAGA ~crew-mixer, at room temperature, for about 10 minute~O
The expandible particles thus treated were fed to a pre-expander, (Erlenbach Mod. K~), with screw-inlet on the bottom and outlet of the pre-expanded material from ~he top, in which they were pre-expanded by mean~
. ;: . , -1SJ4~
of steam at 95-100 C for about 5 minutle R.
The pre-expanded particles were allowed to age in air, at roorn temperature, for approximately 24 hours, and were then introduced into a RAUSCHE lock-making press until filling of a mold having the following S dimensions: 100 ~ 100 x 50 cm. Molding was effected by means of steam at 1 atm. gauge.
The cooling time of the blocks, which depends on the type of organic brominated compound employed, i9 the time required to cause the pressure inside the block to fall to zero, at the conclusion of the treatment -10 with steam.
48 hours after molding, the degree of both shrinkage and sintering was determined on the blocks. `
The latter characteristic was evaluated on a thin plate, obtained from the central paxt of the block by hot-slinging, and determined as percent ~15 of expanded particles which broke when the plate was broken. The characteristics of the expandible particles and of the molded block thus obtained are reported in the following Table I:
.~
20 I ~
' 11 1 .' " ' ..
. . ~ .
1~43S~
~ o o ~ 3 r~ h o c~ O o o bD
_ N C vl C b~ ~
o ~ N ~ V¦ ~ O
N C O O _, O
U
a ~ ~
O ~ Y ~ -.
: - - . I
1~r~ 43 From Table I it can be scen that:
expandible particles with a moiStUre COîltt-`IIt t~qual to that of the particles prepared in the absence of 'brominated compounds, complete absence of odors dUriIlg pre-eXpaIlSiOrl, remarkably lower cooling tilne as compared with that of blocks obtained from particles prepart`d in the absence of brominated compounds, ' block shrinkage <~1%, high sintering degree (70~/o), and fine-cell homogeneous StrUctUre can be achieved only by ~ISillg orgallic bromillated compoullds of type (a) or (b), according to this invention, while in the remaining cases molded blocks are obtained With at least one not thoroughly satisfactory property, e, g.:
cooling time in case ~d,); block shrlnkàg`e'percentage, sintering degree, beads ~oist I e a d o~ors during r--expansion in case (C).
'' 11 1 ` ' .
., ~. ' . ' ~
20 ~ Br l H3 Br Br r Br ~H3 Br Br Br Br ¦¦ Ib) Br-~_ o - CH2 - CH- CH2 Br Br Br ~25 ; .
_7_ .
'''''-:`'' '' .
~ c) Br ~ O - CH2 - CH = CH2 ; ~3r (d) Br ~ O - CHa - CH2 - CH3 .
l Note: Compounds (a) and (b) are in accordance with this invention, while compounds (c) and (d) are given merely for comparative purposes.l I0 Polymerization was carried out at temperatures comprised between 100C and 140C for a total period of 20 hours.
During the polymerization step, 8 parts by weight of an expanding agent consisting of a mixture of n-pentane and isopentane (ratio by weight = ` ~ -70/30) were admixed to the aforesaid suspension.
After cooling to room temperature, filtering, washing with water, and drying at 35-40C for 7 hours, the polymer was subjected to screening in order to obtain expandible polystyrene particles having diameters comprising between 0. 9 and 1. 6 mm. Said particles contained about 6% by . weight of expanding a~;ent.
~:20 The expandible particles were admixed with a conventional non-a~glomerating agent in an amount equal to 0.15% by weight. The admixing wa~ carried out in a SAGA ~crew-mixer, at room temperature, for about 10 minute~O
The expandible particles thus treated were fed to a pre-expander, (Erlenbach Mod. K~), with screw-inlet on the bottom and outlet of the pre-expanded material from ~he top, in which they were pre-expanded by mean~
. ;: . , -1SJ4~
of steam at 95-100 C for about 5 minutle R.
The pre-expanded particles were allowed to age in air, at roorn temperature, for approximately 24 hours, and were then introduced into a RAUSCHE lock-making press until filling of a mold having the following S dimensions: 100 ~ 100 x 50 cm. Molding was effected by means of steam at 1 atm. gauge.
The cooling time of the blocks, which depends on the type of organic brominated compound employed, i9 the time required to cause the pressure inside the block to fall to zero, at the conclusion of the treatment -10 with steam.
48 hours after molding, the degree of both shrinkage and sintering was determined on the blocks. `
The latter characteristic was evaluated on a thin plate, obtained from the central paxt of the block by hot-slinging, and determined as percent ~15 of expanded particles which broke when the plate was broken. The characteristics of the expandible particles and of the molded block thus obtained are reported in the following Table I:
.~
20 I ~
' 11 1 .' " ' ..
. . ~ .
1~43S~
~ o o ~ 3 r~ h o c~ O o o bD
_ N C vl C b~ ~
o ~ N ~ V¦ ~ O
N C O O _, O
U
a ~ ~
O ~ Y ~ -.
: - - . I
1~r~ 43 From Table I it can be scen that:
expandible particles with a moiStUre COîltt-`IIt t~qual to that of the particles prepared in the absence of 'brominated compounds, complete absence of odors dUriIlg pre-eXpaIlSiOrl, remarkably lower cooling tilne as compared with that of blocks obtained from particles prepart`d in the absence of brominated compounds, ' block shrinkage <~1%, high sintering degree (70~/o), and fine-cell homogeneous StrUctUre can be achieved only by ~ISillg orgallic bromillated compoullds of type (a) or (b), according to this invention, while in the remaining cases molded blocks are obtained With at least one not thoroughly satisfactory property, e, g.:
cooling time in case ~d,); block shrlnkàg`e'percentage, sintering degree, beads ~oist I e a d o~ors during r--expansion in case (C).
'' 11 1 ` ' .
., ~. ' . ' ~
Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a process for preparing shaped bodies of expanded styrene-based polymers which comprises, in the order stated, polymerizing styrene or a mixture of styrene with at least one other monomer copolymerizable therewith, adding an expanding agent, pre-expanding the expandible particles obtained, ageing the pre-expanded particles, and molding the pre-expanded aged particles in a mold which is pressure-resistant but not gas-tight, the improvement which consists in effecting the polymerization in the presence of a total amount of 0.001 to 0.5 parts per cent by weight of an organic brominated compound having one of the following general formulae (I) and (II):
(I) (II) in which R' and R" are lower alkyl radicals which may be the same or different and which are optionally halogenated;
R'" and R"" in formula (1) are hydrocarbon groups containing 1 to 8 carbon atoms, which may be the same or different, and which are partially or wholly halogenated;
R'" in formula (II) is a hydrocarbon group containing 1 to 8 carbons and which is partially or wholly halogenated; and n is an integer from 1 to 5.
(I) (II) in which R' and R" are lower alkyl radicals which may be the same or different and which are optionally halogenated;
R'" and R"" in formula (1) are hydrocarbon groups containing 1 to 8 carbon atoms, which may be the same or different, and which are partially or wholly halogenated;
R'" in formula (II) is a hydrocarbon group containing 1 to 8 carbons and which is partially or wholly halogenated; and n is an integer from 1 to 5.
2. The process of claim 1, in which the expanding agent is added during the polymerization.
3. The process according to claim 1, in which the organic brominated compound has the formula:
4. The process according to claim 1, in which the organic brominated compound has the formula:
5. An expandible styrene-based polymer containing a total amount of 0.001 to 0.5 parts per cent by weight of an organic brominated compound having one of the general formulae (I) and (II):
(I) (II) in which R' and R" are lower alkyl radicals which may be the same or different and which are optionally halogenated;
R''' and R"" in formula (I) are hydrocarbon groups containing 1 to 8 carbon atoms, which may be the same or different, and which are partially or wholly halogenated;
R''' in formula (II) is a hydrocarbon group containing 1 to 8 carbons and which is partially or wholly halogenated; and n is an integer from 1 to 5.
(I) (II) in which R' and R" are lower alkyl radicals which may be the same or different and which are optionally halogenated;
R''' and R"" in formula (I) are hydrocarbon groups containing 1 to 8 carbon atoms, which may be the same or different, and which are partially or wholly halogenated;
R''' in formula (II) is a hydrocarbon group containing 1 to 8 carbons and which is partially or wholly halogenated; and n is an integer from 1 to 5.
6. An expandible styrene-based polymer of claim 5, wherein the styrene-based polymer is polystyrene.
7. An expandible styrene-based polymer of claim 5, wherein the styrene-based polymer is copolymer of styrene and at least one other monomer copolymerizable therewith.
8. An expandible styrene-based polymer according to claim 7, wherein the monomers copolymerized with the styrene are selected from the group consisting of alpha-methyl styrene, nuclearly halogenated styrenes, acrylonitrile, methacrylonitrile, esters of acrilic and/or methacrylic acid with alcohols con-taining from 1 to 8 carbon atoms, vinylcarbazole and divinyl-benzene.
9. Blocks molded from particles of the expandible styrene-based polymers according to claim 5 and characterized by a short residence time in the mold, a shrinkage of the block thickness during the molding of ?1%, and a fine-cell homogeneous structure.
10. Expandible particles of a styrene-based polymer according to claim 5, said particles having a total moisture content of less than 0.3% and being further characterized by the complete absence of odors when the particles are subjected to pre-expanding conditions.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IT20706/73A IT979365B (en) | 1973-02-22 | 1973-02-22 | PROCEDURE FOR THE PRODUCTION OF EXPANDABLE POLYSTYRENE PARTICLES TO OBTAIN CELLULAR STRUCTURE PRINTED BODIES WITH HIGH CHARACTERISTICS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1043950A true CA1043950A (en) | 1978-12-05 |
Family
ID=11170833
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA193,035A Expired CA1043950A (en) | 1973-02-22 | 1974-02-20 | Process for preparing expandible particles of styrene-based polymers |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS5736935B2 (en) |
| BE (1) | BE811403A (en) |
| CA (1) | CA1043950A (en) |
| DE (1) | DE2408681C2 (en) |
| DK (1) | DK143943C (en) |
| FR (1) | FR2219179B1 (en) |
| GB (1) | GB1455334A (en) |
| IT (1) | IT979365B (en) |
| NL (1) | NL181584C (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5349272A (en) * | 1976-10-16 | 1978-05-04 | Fuji Electric Co Ltd | Leading current breaking equivalent testing circuit for power breaker |
| GB1591979A (en) * | 1977-06-17 | 1981-07-01 | Montedison Spa | Expandible particles of styrene polymer and process for prreparing same |
| JPS5965271A (en) * | 1982-10-06 | 1984-04-13 | Nissin Electric Co Ltd | Equivalent test of circuit breaker |
| JPS6299241U (en) * | 1985-12-14 | 1987-06-24 | ||
| JP2785295B2 (en) * | 1989-01-31 | 1998-08-13 | 株式会社明電舎 | Leading current interruption test equipment for switchgear |
| US8084511B2 (en) * | 2007-03-08 | 2011-12-27 | Chemtura Corporation | Flame retardants for use in styrenic foams |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE568825A (en) * | 1956-03-10 | |||
| US3372141A (en) * | 1963-02-04 | 1968-03-05 | Dow Chemical Co | Self-extinguishing polystyrene resin compositions |
| GB1107283A (en) * | 1966-04-29 | 1968-03-27 | Berk Ltd | Expandable polystyrene compositions and expanded polystyrene formed therefrom |
| DE1282935B (en) * | 1966-05-27 | 1968-11-14 | Basf Ag | Foamable molding compounds made from styrene polymers containing blowing agents |
| GB1121736A (en) * | 1966-07-20 | 1968-07-31 | Berk Ltd | Improvements in or relating to polyolefin compositions |
| DE2046795B2 (en) * | 1970-09-23 | 1975-05-07 | Chemische Fabrik Kalk Gmbh, 5000 Koeln | Self-extinguishing molding compounds based on acrylonitrile-butadiene-styrene polymers |
-
1973
- 1973-02-22 IT IT20706/73A patent/IT979365B/en active
-
1974
- 1974-02-18 DK DK84674A patent/DK143943C/en not_active IP Right Cessation
- 1974-02-18 NL NLAANVRAGE7402196,A patent/NL181584C/en not_active IP Right Cessation
- 1974-02-20 FR FR7405749A patent/FR2219179B1/fr not_active Expired
- 1974-02-20 CA CA193,035A patent/CA1043950A/en not_active Expired
- 1974-02-21 BE BE141239A patent/BE811403A/en unknown
- 1974-02-21 JP JP2001474A patent/JPS5736935B2/ja not_active Expired
- 1974-02-22 DE DE2408681A patent/DE2408681C2/en not_active Expired
- 1974-02-22 GB GB821374A patent/GB1455334A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FR2219179A1 (en) | 1976-05-14 |
| NL7402196A (en) | 1974-08-26 |
| GB1455334A (en) | 1976-11-10 |
| DK143943C (en) | 1982-04-13 |
| DE2408681A1 (en) | 1974-09-05 |
| IT979365B (en) | 1974-09-30 |
| FR2219179B1 (en) | 1976-05-14 |
| NL181584C (en) | 1987-09-16 |
| BE811403A (en) | 1974-08-21 |
| JPS502064A (en) | 1975-01-10 |
| DE2408681C2 (en) | 1989-11-02 |
| JPS5736935B2 (en) | 1982-08-06 |
| NL181584B (en) | 1987-04-16 |
| DK143943B (en) | 1981-11-02 |
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