CA1316352C - Nucleating agents (pore regulators) for the preparation of directly gassed thermoplastic foams - Google Patents
Nucleating agents (pore regulators) for the preparation of directly gassed thermoplastic foamsInfo
- Publication number
- CA1316352C CA1316352C CA000513458A CA513458A CA1316352C CA 1316352 C CA1316352 C CA 1316352C CA 000513458 A CA000513458 A CA 000513458A CA 513458 A CA513458 A CA 513458A CA 1316352 C CA1316352 C CA 1316352C
- Authority
- CA
- Canada
- Prior art keywords
- talc
- agent
- directly
- gassed
- nucleating
- 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 - Fee Related
Links
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
- C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
- C08J9/06—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a chemical blowing agent
- C08J9/08—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a chemical blowing agent developing carbon dioxide
-
- 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
- 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
- C08J9/0066—Use of inorganic compounding ingredients
-
- 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
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
- C08K3/24—Acids; Salts thereof
- C08K3/26—Carbonates; Bicarbonates
-
- 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
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/34—Silicon-containing compounds
-
- 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
- C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
-
- 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
- C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
- C08K5/0083—Nucleating agents promoting the crystallisation of the polymer matrix
-
- 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
- C08K5/09—Carboxylic acids; Metal salts thereof; Anhydrides thereof
Abstract
Abstract The invention relates to new nucleating agents for the preparation of directly gassed thermoplastic foams. The new agents consist of a combination of citric acid, the salts or esters thereof and carbonate or bicarbonate and talc.
Description
~3~3~
The invention relates to a new nucleating agent ~pore regulator) for the preparation of directly gassed thermoplastic foams.
It is known to add physically acting propellants (i.e. propellants with a boiling temperature below the p~ocessing temperature of the pla~tics) to the thermoplastic material when preparing structural foams. Nucleating agents are used as pore regulators to control the cell structure. One of the most frequently used nucleating agents is talc, which is generally added to the thermoplastic material in amounts of from 1.0 to 2.5%. The use of talc or other non-decomposing pore regulators as so-called "passive nucleating agents" has the disadvantage that when waste products from the plastics processing, the regenerated material, is reused the "passive nucleating agent" is always recycled into the process again, and it is very difficult to estimate the nucleating activity of the non-decomposed pore regulator from the regenerated material.
If solids such as talc are mixed with the plastics in concentrations of more than about 1~, the quality of the plastics, particularly its colour, structu~e and gloss, are afected.
Therefore, so-called "active nucleating agents"
are becoming increasingly importantO "Active nucleating agents" are pore regulators which decompose during the extrusion or injection moulding process; the regenerated material then contains no (or at least fewer) constituents with a nucleating effect and can be reused without any substantial loss of quality.
Particular mention should be made of systems which cleave carbon dioxide, of which sodium bicarbonate ;
:
., . : : , ~3~3~2 or cltric acl~ esters (~E-OS 34 11 319) or the comblnatlon o~
cltric acid or sodlurn citrate wlth sodlum bicarbonate or sodlum carbonate (Japanese Patent 715 375) have been ~escrlbed. The citrlc acld/sodlum blcarbonate system ls effectlve as a pore regulator when added ln amounts o~ from 0.4 to 1.0%
It has now been found that mixtures of citrlc acld, citrlc acld esters or salts of cltrlc acld with carbonates or bicarbonates as active nucleating agents with talc as the passlve nucleatlng agent ln a wlde range of mixlng ratlos have better nucleatlon properties than the actlve or passlve nucleatlng agents on their own.
The lnventlon thus relates to an agent for nucleatlng directly gassed thermoplastlc foams conslstlng of a mlxture of components A, B and C, whereln A represents monosodium citrate and :` B represents an alkall, alkallne earth or ammonium carbonate, or an alkall, alkaline earth or ammonium bicarbonate and C represents talc, whereln components A and ~ are present in , a stoichlometrlc or substantlally stolchlometrlc ratlon and . wherein components A, B and C are present ln the ratlo . [(A + B): c] from [9:1] to [1:9]
and thls agent may, if deslred, contaln the conventlonal flow promoting agents, release agents and lubrlcants.
`, :
.-,`' :` .
, . ~ . .
1 3163~
, .
. ~
The two components A and B represent the system described hereinbefore of an active nucleating agent (propellant) whilst component C represents the system of a passive nucleating agent.
The citric acid may be present in pure form or as a hydrate and in the form of its alkali, alkaline earth or ammonium salts. The salts of the monobasic citric acid are preferred, such as monosodium citrate, calcium citrate and monoammonium citrate or a 2:1 mixture of citric acid and trisodium citrate.
Particular mention should be made of monosodium citrate.
Suitable citric acid esters are the mono- and diesters of alcohols having up to 8 carbon atoms. Lower alcohols are methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, sec.-butanol, tert.-butanol, n-pentan-l-ol, n-pentan-2-ol, n-pentan-3-ol and the isomeric pentanols, n-hexan-l-ol, n-hexan-2-ol, n-hexan-3-ol and the isomeric hexanols, n-heptan-l-ol, n-heptan-2-ol, n-heptan-3-ol, n-heptan-4-ol and the isomeric heptanols, n-octan-l-ol, n-octan-2-ol, n-octan-3-ol, n-octan-4-ol and the isomeric octanols, cyclopentanol and cyclohexanol.
It is also possible to use esters of diols or polyols with up to 8 carbon atoms, such as ethyleneglycol, glycerol, pentaerythritol or lower polyethylene glycols with up to 8 carbon atoms, e.g. diethyleneglycol, triethyleneglycol or tetraethyleneglycol~
s Particular mention should be made of the mono-or diesters of monohydric alcohols with up to 6 carbon atoms.
The mono- or diesters of monohydric alcohols with up to 4 carbon atoms are preferred.
., ,....
..... , ~
~31~3~2 , . .
The monoesters such as monomethylcitrate, monoethylcitrate, monopropylcitrate, monoisopropylcitrate, mono-n-butylcitrate and mono-tert butylcitrate are particularly preferred.
Monoesters according to the preceding defini~ion include both the citric acid ~-esters and also the citric acid ~-esters or mixtures of ~- and ~-monoesters of any desired composition. By mixing the ~- and ~-esters in any desired proportions it is possible to obtain mixtures with lower melting points than the pure esters.
Diesters in accordance with the preceding definition include both the ~,'-diesters of citric acid and also the ~ diesters or mixtures of the a,a'-and a,~-diesters of citric acid.
By mixing the a,~'- and a,~-diesters in suitable proportions it is possible to obtain mixtures with lower melting points than the pure diesters.
Diesters according to the preceding definition also include mixed esters of two different alcohols, and this term also includes all possible structurally-isomeric and stereoisomeric compounds in pure form or in any mixture.
The carbonate or bicarbonate component (B) used may be a carbonate or bicarbonate of the alkali metals or the alkaline earth metals or of ammonium.
Sodium, potassium and calcium are preferred.
Particular mention should be made of sodium carbonate and sodium bicarbonate.
The citric acid component (component A) is mixed .
;....... .
~ 3 ~ 2 with the carbonate or bic~rbonate component tcomponent B) preferably in a stoichiornetric or nearly stoichiometric ratio, so that the free acid equivalents of component A serve formally to neutralise component B and as a result the optimum quantity of carbon dioxide is released.
The standard commercial grades of talc may be used as the talc (component C). Grades of talc which are also used for pharmaceutical preparations are preferred since these will be safe to eat and will therefore not affect the quali~y of the material in this respect. It should be particularly emphasised that these grades of talc do not contain any mineral fibres which could be harmful to the lungs.
The usual agents for improving flow or release agents or lubricants may be added to the mi~ture according to the invention.
These additives are generally known in the art.
Examples include metal-soaps such as calcium or zinc or magnesium stearate; paraffins; silicates such as aerosil; silicones, waxes; fats.
. ~
Suitable thermoplastics include:
polyethylenes; ethylene-vinylacetate copolymers;
ethylene-ethylacrylates; ionomeric polyethylenes;
polypropylenes; polybutenes; polymethylpentenes;
polystyrenes; high-impact polystyrenes; styrene-acrylonitrile copolymers; acrylic-butadiene-styrene copolymers; ASA, polyvinylcarbazoles; polyvinylchlorides;
polytrifluoroethylenes; polytetrafluoroethylene;
perfluoropropylenes; polyvinylidene fluorides;
ethylene-tetrafluoroethylene copolymers; polymethyl-methacrylates; polyamides; polyethyleneglycol tere-*acrylonitrilestyryl acrylate .: .
, ~ . .. .
~`
13~63~
, ..
phthalates; ~olybutylene terephthalates, polyoxy-methylenes; polycarbonates; chlorinated polyethers;
phenoxy resins; polyphenylene oxides; polysulphones;
polyethersulphones; polyphenylenesulphides; polyurethane elastomers; cellulose acetates; cellulose propionates;
cellulose-aceto-butyrates and other thermoplastics or elastomers.
The three components A, B and C may be mixed together as a finely ground free flowing powder. It is also possible to coat the mixture by conventional methods (to render it water-repellant) or to encapsulate it, whilst all three components may be encapsulated, coated or made water-repellant together or one or two components are first encapsulated, coated or made water-repellant and the remaining components are then added.
Numerous substances are suitable for encapsulating, coating or rendering water-repellant. Those substances which melt or are already molten at the temperatures conventional for thermoplastic melts but are solid or solidify in a waxy state at ambient temperature are preferred.
In addi~ion to the numerous waxes, fatty acids and the esters and salts thereof are preferred calcium stearate and magnesium stearate and the fatty acid glycerides are particularly suitable.
The ratio of talc (C) to the,other two components (A ~ B) can be freely selected within the limits (C) : (A ~ B) irom 1:9 to 9:1. The range (C) :
~A ~ B) from 5:5 to 8:2 is preferred.
Particula~ mention should be made of mixtures of monosodium citrate and sodium bicarbonate and talc ;'`
~,J
. . .
~3163~2 and citric acid, sodium bicarbonate and talc.
It has proved advantageous if first of all the sodium bicarbonate on its own and/or the citric acid on its own is made water-repellant with calcium stearate or fatty acid esters, because these mixtures are particularly resistant to moisture in the air and will not go lumpy or decompose even when s~ored for lengthy periods.
For the citric acid esters, mixtures of monoisopropyl-citrate with sodium hydrogen carbonate and talc are preferred. The liquid monoisopropylcitrate is encapsulated using methods known ~ se or may be incorporated in plastics in the form of katches.
Exampte 1 Preparation of directly gassed polystyrene structural foam films The tests are carried out using a Berstoff-Tandem apparatus. 5-7~ of a 1:1 mixture of trichloromonofluoro-methane and dichlorodifluoromethane are used as propellant. The thermoplastic material used is industrial-grade polystyrene (type DOW 648).
The quantities of propellant and nucleating agent specified relate to the quantity of polystyrene used, and the addition of nucleating agent is varied (whilst the addition of propellant remains constant) until the polystyrene films have approximately the same cell structure. The film described in Experiment number 1 serves as the standard.
' E~periment 1 (prior art) Polystyrene: polystyrene of the Styron 648 type ~ rra de ~ ~r~
,.
~' .
-~-` 1 316~2 .. g (made by Dow Chemicals) Nucleating agent: 1.7% tal~
Results: uniform structure, film has a pale yellow shimmer Experiment 2 (prior art) Polystyrene: polystyrene of the Styron 648 type Nucleating agent: 0.45~ of a mixture of monoscdium citrate and sodium bicarbonate (corresponding to Japanese Patent 715 ~375) Results: fine uniform structure Exp~__ment 3 (according to the invention) Polystyrene: Polystyrene Dow 648 Nucleating agent: 0.35% talc 0.09% of a mixture of monosodium citrate and sodium hydrogen carbonate (according to Japanese Patent 715 375) Results: fine uniform structure with finer pores than in Experiment 1.
.
The electron-microscope pictures enclosed as Annex 1 and 2 are sections taken longitudinally and at right angles to the direction of extrusion of the foam film and demonstrate the improvement in pore quality.
Examples 4 6 Direct gassing of LDPE (i.e. low density polyethylene3 Single screw extruder with gassing device, tubular die ~conventional construction for the manufacture o foam filmsl.
LDPE:~ density about 0.918 Melting index about 2 Gas: dichlorodifluoro ethane.
Q~antity of qas: 4 - 5~
Foam density: 0.3 - 0.4 g/ml radem~r k .
. .
. .
,;- - - -- ~ :
' , , .
:~ , ~3~ ~3~
Experiment 4: ~prior art) LDPE: as above Nucleating agent: 0.6 - 0.8% talc Result: uniform foam structure, colour yellowy-grey Experiment 5 (prior art) LDPE: as above Nucleating agent: 0.3 - 0.4~ analogously to Experiment 2 Result: uniform fine structure, colour lighter than in Experiment 4 Experiment 6:
LDPE: as above Nucleating agent: 0.25 - 0.4% analogously to Experiment 3 Result: uniform fine structure, colour lighter than Experiment 4 , ;
, :
` ~ : , .
: - :
The invention relates to a new nucleating agent ~pore regulator) for the preparation of directly gassed thermoplastic foams.
It is known to add physically acting propellants (i.e. propellants with a boiling temperature below the p~ocessing temperature of the pla~tics) to the thermoplastic material when preparing structural foams. Nucleating agents are used as pore regulators to control the cell structure. One of the most frequently used nucleating agents is talc, which is generally added to the thermoplastic material in amounts of from 1.0 to 2.5%. The use of talc or other non-decomposing pore regulators as so-called "passive nucleating agents" has the disadvantage that when waste products from the plastics processing, the regenerated material, is reused the "passive nucleating agent" is always recycled into the process again, and it is very difficult to estimate the nucleating activity of the non-decomposed pore regulator from the regenerated material.
If solids such as talc are mixed with the plastics in concentrations of more than about 1~, the quality of the plastics, particularly its colour, structu~e and gloss, are afected.
Therefore, so-called "active nucleating agents"
are becoming increasingly importantO "Active nucleating agents" are pore regulators which decompose during the extrusion or injection moulding process; the regenerated material then contains no (or at least fewer) constituents with a nucleating effect and can be reused without any substantial loss of quality.
Particular mention should be made of systems which cleave carbon dioxide, of which sodium bicarbonate ;
:
., . : : , ~3~3~2 or cltric acl~ esters (~E-OS 34 11 319) or the comblnatlon o~
cltric acid or sodlurn citrate wlth sodlum bicarbonate or sodlum carbonate (Japanese Patent 715 375) have been ~escrlbed. The citrlc acld/sodlum blcarbonate system ls effectlve as a pore regulator when added ln amounts o~ from 0.4 to 1.0%
It has now been found that mixtures of citrlc acld, citrlc acld esters or salts of cltrlc acld with carbonates or bicarbonates as active nucleating agents with talc as the passlve nucleatlng agent ln a wlde range of mixlng ratlos have better nucleatlon properties than the actlve or passlve nucleatlng agents on their own.
The lnventlon thus relates to an agent for nucleatlng directly gassed thermoplastlc foams conslstlng of a mlxture of components A, B and C, whereln A represents monosodium citrate and :` B represents an alkall, alkallne earth or ammonium carbonate, or an alkall, alkaline earth or ammonium bicarbonate and C represents talc, whereln components A and ~ are present in , a stoichlometrlc or substantlally stolchlometrlc ratlon and . wherein components A, B and C are present ln the ratlo . [(A + B): c] from [9:1] to [1:9]
and thls agent may, if deslred, contaln the conventlonal flow promoting agents, release agents and lubrlcants.
`, :
.-,`' :` .
, . ~ . .
1 3163~
, .
. ~
The two components A and B represent the system described hereinbefore of an active nucleating agent (propellant) whilst component C represents the system of a passive nucleating agent.
The citric acid may be present in pure form or as a hydrate and in the form of its alkali, alkaline earth or ammonium salts. The salts of the monobasic citric acid are preferred, such as monosodium citrate, calcium citrate and monoammonium citrate or a 2:1 mixture of citric acid and trisodium citrate.
Particular mention should be made of monosodium citrate.
Suitable citric acid esters are the mono- and diesters of alcohols having up to 8 carbon atoms. Lower alcohols are methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, sec.-butanol, tert.-butanol, n-pentan-l-ol, n-pentan-2-ol, n-pentan-3-ol and the isomeric pentanols, n-hexan-l-ol, n-hexan-2-ol, n-hexan-3-ol and the isomeric hexanols, n-heptan-l-ol, n-heptan-2-ol, n-heptan-3-ol, n-heptan-4-ol and the isomeric heptanols, n-octan-l-ol, n-octan-2-ol, n-octan-3-ol, n-octan-4-ol and the isomeric octanols, cyclopentanol and cyclohexanol.
It is also possible to use esters of diols or polyols with up to 8 carbon atoms, such as ethyleneglycol, glycerol, pentaerythritol or lower polyethylene glycols with up to 8 carbon atoms, e.g. diethyleneglycol, triethyleneglycol or tetraethyleneglycol~
s Particular mention should be made of the mono-or diesters of monohydric alcohols with up to 6 carbon atoms.
The mono- or diesters of monohydric alcohols with up to 4 carbon atoms are preferred.
., ,....
..... , ~
~31~3~2 , . .
The monoesters such as monomethylcitrate, monoethylcitrate, monopropylcitrate, monoisopropylcitrate, mono-n-butylcitrate and mono-tert butylcitrate are particularly preferred.
Monoesters according to the preceding defini~ion include both the citric acid ~-esters and also the citric acid ~-esters or mixtures of ~- and ~-monoesters of any desired composition. By mixing the ~- and ~-esters in any desired proportions it is possible to obtain mixtures with lower melting points than the pure esters.
Diesters in accordance with the preceding definition include both the ~,'-diesters of citric acid and also the ~ diesters or mixtures of the a,a'-and a,~-diesters of citric acid.
By mixing the a,~'- and a,~-diesters in suitable proportions it is possible to obtain mixtures with lower melting points than the pure diesters.
Diesters according to the preceding definition also include mixed esters of two different alcohols, and this term also includes all possible structurally-isomeric and stereoisomeric compounds in pure form or in any mixture.
The carbonate or bicarbonate component (B) used may be a carbonate or bicarbonate of the alkali metals or the alkaline earth metals or of ammonium.
Sodium, potassium and calcium are preferred.
Particular mention should be made of sodium carbonate and sodium bicarbonate.
The citric acid component (component A) is mixed .
;....... .
~ 3 ~ 2 with the carbonate or bic~rbonate component tcomponent B) preferably in a stoichiornetric or nearly stoichiometric ratio, so that the free acid equivalents of component A serve formally to neutralise component B and as a result the optimum quantity of carbon dioxide is released.
The standard commercial grades of talc may be used as the talc (component C). Grades of talc which are also used for pharmaceutical preparations are preferred since these will be safe to eat and will therefore not affect the quali~y of the material in this respect. It should be particularly emphasised that these grades of talc do not contain any mineral fibres which could be harmful to the lungs.
The usual agents for improving flow or release agents or lubricants may be added to the mi~ture according to the invention.
These additives are generally known in the art.
Examples include metal-soaps such as calcium or zinc or magnesium stearate; paraffins; silicates such as aerosil; silicones, waxes; fats.
. ~
Suitable thermoplastics include:
polyethylenes; ethylene-vinylacetate copolymers;
ethylene-ethylacrylates; ionomeric polyethylenes;
polypropylenes; polybutenes; polymethylpentenes;
polystyrenes; high-impact polystyrenes; styrene-acrylonitrile copolymers; acrylic-butadiene-styrene copolymers; ASA, polyvinylcarbazoles; polyvinylchlorides;
polytrifluoroethylenes; polytetrafluoroethylene;
perfluoropropylenes; polyvinylidene fluorides;
ethylene-tetrafluoroethylene copolymers; polymethyl-methacrylates; polyamides; polyethyleneglycol tere-*acrylonitrilestyryl acrylate .: .
, ~ . .. .
~`
13~63~
, ..
phthalates; ~olybutylene terephthalates, polyoxy-methylenes; polycarbonates; chlorinated polyethers;
phenoxy resins; polyphenylene oxides; polysulphones;
polyethersulphones; polyphenylenesulphides; polyurethane elastomers; cellulose acetates; cellulose propionates;
cellulose-aceto-butyrates and other thermoplastics or elastomers.
The three components A, B and C may be mixed together as a finely ground free flowing powder. It is also possible to coat the mixture by conventional methods (to render it water-repellant) or to encapsulate it, whilst all three components may be encapsulated, coated or made water-repellant together or one or two components are first encapsulated, coated or made water-repellant and the remaining components are then added.
Numerous substances are suitable for encapsulating, coating or rendering water-repellant. Those substances which melt or are already molten at the temperatures conventional for thermoplastic melts but are solid or solidify in a waxy state at ambient temperature are preferred.
In addi~ion to the numerous waxes, fatty acids and the esters and salts thereof are preferred calcium stearate and magnesium stearate and the fatty acid glycerides are particularly suitable.
The ratio of talc (C) to the,other two components (A ~ B) can be freely selected within the limits (C) : (A ~ B) irom 1:9 to 9:1. The range (C) :
~A ~ B) from 5:5 to 8:2 is preferred.
Particula~ mention should be made of mixtures of monosodium citrate and sodium bicarbonate and talc ;'`
~,J
. . .
~3163~2 and citric acid, sodium bicarbonate and talc.
It has proved advantageous if first of all the sodium bicarbonate on its own and/or the citric acid on its own is made water-repellant with calcium stearate or fatty acid esters, because these mixtures are particularly resistant to moisture in the air and will not go lumpy or decompose even when s~ored for lengthy periods.
For the citric acid esters, mixtures of monoisopropyl-citrate with sodium hydrogen carbonate and talc are preferred. The liquid monoisopropylcitrate is encapsulated using methods known ~ se or may be incorporated in plastics in the form of katches.
Exampte 1 Preparation of directly gassed polystyrene structural foam films The tests are carried out using a Berstoff-Tandem apparatus. 5-7~ of a 1:1 mixture of trichloromonofluoro-methane and dichlorodifluoromethane are used as propellant. The thermoplastic material used is industrial-grade polystyrene (type DOW 648).
The quantities of propellant and nucleating agent specified relate to the quantity of polystyrene used, and the addition of nucleating agent is varied (whilst the addition of propellant remains constant) until the polystyrene films have approximately the same cell structure. The film described in Experiment number 1 serves as the standard.
' E~periment 1 (prior art) Polystyrene: polystyrene of the Styron 648 type ~ rra de ~ ~r~
,.
~' .
-~-` 1 316~2 .. g (made by Dow Chemicals) Nucleating agent: 1.7% tal~
Results: uniform structure, film has a pale yellow shimmer Experiment 2 (prior art) Polystyrene: polystyrene of the Styron 648 type Nucleating agent: 0.45~ of a mixture of monoscdium citrate and sodium bicarbonate (corresponding to Japanese Patent 715 ~375) Results: fine uniform structure Exp~__ment 3 (according to the invention) Polystyrene: Polystyrene Dow 648 Nucleating agent: 0.35% talc 0.09% of a mixture of monosodium citrate and sodium hydrogen carbonate (according to Japanese Patent 715 375) Results: fine uniform structure with finer pores than in Experiment 1.
.
The electron-microscope pictures enclosed as Annex 1 and 2 are sections taken longitudinally and at right angles to the direction of extrusion of the foam film and demonstrate the improvement in pore quality.
Examples 4 6 Direct gassing of LDPE (i.e. low density polyethylene3 Single screw extruder with gassing device, tubular die ~conventional construction for the manufacture o foam filmsl.
LDPE:~ density about 0.918 Melting index about 2 Gas: dichlorodifluoro ethane.
Q~antity of qas: 4 - 5~
Foam density: 0.3 - 0.4 g/ml radem~r k .
. .
. .
,;- - - -- ~ :
' , , .
:~ , ~3~ ~3~
Experiment 4: ~prior art) LDPE: as above Nucleating agent: 0.6 - 0.8% talc Result: uniform foam structure, colour yellowy-grey Experiment 5 (prior art) LDPE: as above Nucleating agent: 0.3 - 0.4~ analogously to Experiment 2 Result: uniform fine structure, colour lighter than in Experiment 4 Experiment 6:
LDPE: as above Nucleating agent: 0.25 - 0.4% analogously to Experiment 3 Result: uniform fine structure, colour lighter than Experiment 4 , ;
, :
` ~ : , .
: - :
Claims (7)
1. Agent for nucleating directly gassed thermoplastic foams, consisting of a mixture of components A, B and C, wherein A represents monosodium citrate and B represents an alkali, alkaline earth or ammonium carbonate; or an alkali, alkaline earth or ammonium bicarbonate and C represents talc, wherein components A and B are present in a stoichiometric or substantially stoichiometric ratio and wherein components A, B and C are present in the ratio [(A + B) :
C] from [9:1] to 11:9].
C] from [9:1] to 11:9].
2. Agent as claimed in claim 1 in admixture with one or more flow promoters, release agents or lubricants.
3. Agent as claimed in claim 1 or 2 wherein A represents monosodium citrate, B represents sodium carbonate or sodium bicarbonate, C represents talc.
4. Agent as claimed in claim 1 or 2, consisting of monosodium citrate, sodium bicarbonate and talc.
5. Agent for nucleating directly gassed thermoplastic forms comprising monosodium citrate, sodium bicarbonate and talc, in which the monosodium citrate and sodium bicarbonate are present in a stoichiometric or substantially stoichiometric ratio.
6. Process for preparing directly gassed thermoplastic foams, characterised in that 0.1 to 1.0% of an agent as claimed in claims 1, 2, 4 or 5 is added to the thermoplastic material.
7. Use of a nucleating agent as claimed in claims 1, 2, 4 or 5 for the preparation of directly gased thermoplastic foams.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19853524704 DE3524704A1 (en) | 1985-07-11 | 1985-07-11 | NUCLEATING AGENT (PORE REGULATOR) FOR THE PRODUCTION OF DIRECTLY BACTERIZED THERMOPLASTIC FOAMS |
| DEP3524704.5 | 1985-07-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1316352C true CA1316352C (en) | 1993-04-20 |
Family
ID=6275451
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000513458A Expired - Fee Related CA1316352C (en) | 1985-07-11 | 1986-07-10 | Nucleating agents (pore regulators) for the preparation of directly gassed thermoplastic foams |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0211250B1 (en) |
| JP (1) | JPH0672192B2 (en) |
| AT (1) | ATE64605T1 (en) |
| CA (1) | CA1316352C (en) |
| DE (2) | DE3524704A1 (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3722539A1 (en) * | 1987-07-08 | 1989-01-19 | Reichenecker Hans Storopack | Foamed moulded article |
| US5116881A (en) * | 1990-03-14 | 1992-05-26 | James River Corporation Of Virginia | Polypropylene foam sheets |
| JPH08863B2 (en) * | 1990-12-27 | 1996-01-10 | 積水化成品工業株式会社 | Method for producing polystyrene-based resin foam |
| DE4234225A1 (en) * | 1992-10-10 | 1994-04-14 | Roehm Pharma Gmbh | Stable topical formulations with good active ingredient release capacity containing at least one lipophilized macrolide antibiotic |
| ATE290041T1 (en) † | 1997-12-19 | 2005-03-15 | Trexel Inc | MICROCELLULAR FOAM EXTRUSION/BLOW MOLDING PROCESS AND ARTICLE MADE THEREFROM |
| AU774491B2 (en) | 1999-12-24 | 2004-07-01 | Huntsman International Llc | Gas assisted injection moulding |
| DE10036101A1 (en) * | 2000-07-25 | 2002-03-28 | Volker Heppert | Process for the production of foamed plastic objects |
| JP2007017421A (en) * | 2004-10-28 | 2007-01-25 | Matsushita Electric Ind Co Ltd | Cable-like piezo-electric element and its manufacturing method |
| DE102009028562A1 (en) * | 2009-08-14 | 2011-02-17 | Chemische Fabrik Budenheim Kg | Foaming agent for plastics |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3444283A (en) * | 1965-11-08 | 1969-05-13 | Mobil Oil Corp | Method for direct injection extrusion of polystyrene foam |
| JPS5721453B2 (en) * | 1973-07-06 | 1982-05-07 | ||
| JPS5359756A (en) * | 1976-11-11 | 1978-05-29 | Mitsubishi Chem Ind | Manufacture of polyethylene foam |
| JPS52121669A (en) * | 1976-11-12 | 1977-10-13 | Sekisui Plastics | Process for manufacture of extruded polyolefin foam |
| JPS57105429A (en) * | 1980-12-24 | 1982-06-30 | Japan Styrene Paper Co Ltd | Preparation of thick board of foamed polystyrene resin |
| FR2500463A1 (en) * | 1981-02-24 | 1982-08-27 | Solvay | |
| JPS5836005A (en) * | 1981-08-28 | 1983-03-02 | Hitachi Ltd | Amplifying circuit |
| JPS58111834A (en) * | 1981-12-25 | 1983-07-04 | Japan Styrene Paper Co Ltd | Preparation of extruded polystyrene sheet foam |
| DE3411319C2 (en) * | 1984-03-28 | 1986-12-04 | Boehringer Ingelheim KG, 6507 Ingelheim | Use of citric acid esters as blowing and / or nucleating agents for the production of thermoplastic plastic foams |
-
1985
- 1985-07-11 DE DE19853524704 patent/DE3524704A1/en not_active Ceased
-
1986
- 1986-07-05 DE DE8686109202T patent/DE3679867D1/en not_active Expired - Lifetime
- 1986-07-05 EP EP86109202A patent/EP0211250B1/en not_active Expired - Lifetime
- 1986-07-05 AT AT86109202T patent/ATE64605T1/en not_active IP Right Cessation
- 1986-07-10 CA CA000513458A patent/CA1316352C/en not_active Expired - Fee Related
- 1986-07-10 JP JP61162914A patent/JPH0672192B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0211250A3 (en) | 1988-03-23 |
| EP0211250B1 (en) | 1991-06-19 |
| JPH0672192B2 (en) | 1994-09-14 |
| DE3524704A1 (en) | 1987-01-15 |
| JPS6264835A (en) | 1987-03-23 |
| EP0211250A2 (en) | 1987-02-25 |
| ATE64605T1 (en) | 1991-07-15 |
| DE3679867D1 (en) | 1991-07-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |