CA1100697A - Foamable thermoplastic polyester compositions - Google Patents
Foamable thermoplastic polyester compositionsInfo
- Publication number
- CA1100697A CA1100697A CA292,789A CA292789A CA1100697A CA 1100697 A CA1100697 A CA 1100697A CA 292789 A CA292789 A CA 292789A CA 1100697 A CA1100697 A CA 1100697A
- Authority
- CA
- Canada
- Prior art keywords
- composition
- polyester
- zinc
- flame retardant
- foamed
- 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
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
- C08J9/0066—Use of inorganic compounding ingredients
-
- 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
-
- 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
- C08K3/20—Oxides; Hydroxides
- C08K3/22—Oxides; Hydroxides of metals
-
- 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
- C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
- C08J2367/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
Landscapes
- 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)
- Inorganic Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Thermoplastic polyester compositions are provided which are moldable to foamed plastic articles, the compositions comprising a high molecular weight polyester alone of in combination with a flame retardant agent, and a foaming agent selected from the group consisting essentially of zinc car-bonate, zinc formate and mixtures thereof.
Thermoplastic polyester compositions are provided which are moldable to foamed plastic articles, the compositions comprising a high molecular weight polyester alone of in combination with a flame retardant agent, and a foaming agent selected from the group consisting essentially of zinc car-bonate, zinc formate and mixtures thereof.
Description
8C~-2082 This inventiorl relates to thermoplas-tic polyester compositions capable of being molded to .foamed articles with excellent properties. More particularly, it pertains to com~
positions comprising a normally Elammab:Le high molecular weight polyester with or without a flame retardant agent, and as a foaming agent, a thermally decompo~3able zinc compound selacted rrom among æinc carbonate, zinc formate and mixtures thereof~
The use of high .molecular weight polyesters in thermoplastic molding compositions is well known to those - skilled in the art. Such polyesters provide compositions with excellent moldability, and molded articles therefrom having a smooth and glossy surface appearance, high strength, stifEness, temperature resistance and othex desirable properties.
With the development of foamed plastics technology, polyesters have enjoyed increasing use in the manufacture of foamed plastic articles. This typically involves the admixture ~ of a "blowing agent", e.g., a thermally decomposable solid 20 or liquid chemical compound, with a thermoplastic polyester resin and the transfer of the resulting foamable mixture to a mold where a foamed ar-ticle is Eormed.
However, in addition to the need for highly efficien-t foaming agents, it is desirable to improve the burning behavior of foamed compositions containing the afore-mentioned polyesters~
The flammability of polyesters has been reduced by using flame retarding agents and such compositions are described in various patents and publications~
It has now been surpri.singly discovered that csrtain æinc compounds are uniquely effective foaming agents~ They also improve the flame retardancy of foamed thermoplastic polyester molding com~ositions. While not wishing to be bourld by ~ ~ 110 ~697 8CH-2082 any theory of the invention, it is believed that the particular zinc compounds decompose at the molding temperature of the polyester resin to libera-te a gas, e~g., carbon dioxide or carbon monoxide, which causes foami.ng, and the production oE
zinc oxide. The latter appears to act as an anti-drip agent.
The additive levels most suitabl.e for the two purposes are about the same. Thus, the use of the zinc compounds in this manner makes possible the fabrication of super.ior ~oamed plastic articles. As an additional benefit, the articles are significantly improved in a key flammability characteristic, i.e., the reduced tendency to drip when near to an open flame.
According to this invention there are provided foamable thermoplastic molding compositions which comprise, in intimate admixture:
(a) a high molecular weight polyester resin; and (b~ a thermally decomposable foaming agent selected from the group consisting oE zinc carbonate, zinc formate and mixtures thereof, 20 said agent being present in an amount at least sufficient to cause foaming in said thermo-plast.ic composition during molding~
The eEfectiveness of zinc carbonate in the present compositions is believed to be due to the fact that it decom~
poses to zinc oxide and carbon dioxide at the molding tempera-ture of polyester resins~ These two products bring about the changes in -the resin that are the basis of the invention - -the carbon dioxide acts as a foaming agent and the zinc oxide appears to act as an agent to retard dripping when the foamed article is near an open ~lame. The zinc carbonate decomposi-tion temperature, about ~40~C. in a melt point capillary, is such that compositions of polyester resins or related materials 8CH 20~2 6~7 containing undecomposed zinc carbonate are accessible. A
valuable application o:E this invention is in the production of foamed polyester resin having the improved behavi.or when near open flames.
The zinc salt which has been found to serve as an e~ficient foaming agent at about the same additive level as for zinc carbonate is zinc formate. Zinc formate is at least as . effective as the carbonate, apparently a:Lso forming zinc oxide in situ, represented as follows:
o Zn(OCH~2 ~ ZnO + 2 CO -~ ~2 In air, zinc ~ormate liberates gas vigorously ak about 280C.
In th~ polyester resin composition melt at moldiny termperatures, the gas causes the foamed composition -to be produced.
In preferred compositions, the foaming agent is present in an amount of at least about 0.5% by weight of (a) and (b), more preferably from about 0.5 to about 5% by weight, based on (a) and (bj combined.
The high molecular weight normally flammable poly-esters used in the present compositions are preferably poly-meric glycol esters of terephthalic acid and isophthalic acids.
They are available commercially or can be prepared by known techniques such as ~y the alcoholysis of esters of the phthalic acid with a ylycol and subsequent polymerization, by heating glycols with the free acids or with halide derivatives thereoE, and similar processes~ These are described in U.S. 2,465,319 dated March 22, 1949 and U.S. 3,047,539 dated July 31, 1962 and elsewhere~
Although the glycol portion of the polyester can con-tain from two to ten carbon atoms, it is preferred that it con-tain from two to four carbon a-toms in the form of linear me-thyl-ene chains.
More preferably, the polyesters will be of the Eamily consisting of high molecular weight, polymeric glycol terephthal-ates or isophthalates having repeating units of the general formula: 1 ~C112)n 0 C ~3/ C --wherein n is a whole number of from two to four t and mixtures of such esters, including copolyesters of terephthalic and isophthalic acids of up to about 30 mole % isophthalic units.
Especially preferred polyesters are poly~ethylene tere-phthalate) and poly(l,4-butylene terephthalate). Special mention is made of the latter because it crystallizes at such a good rate that it may be used for injection molding without the need for nucleating agents or long cycles, as is sometimes necessary with poly(ethylene terephthalate).
Illustratively, the high molecular weight polyester will have an intrinsic viscosity of at least about 0.4 decilit-ers/gram and preferably, at least 0.8 deciliters/gram as measured in a 60:40 phenol/tetrachloroethane mixture at 30C.
In the preferred embodiments, the optional f]ame re-tardant agent can be selected from among materials conventionally employed for such purposes. Illustrative flame retardant addi-tives are disclosed in U.S. 3,833,685 dated Septem~er 3, 1974, U.S. 3,334,154 dated August 1, 1967, U.S. 3,915,926 dated October 28, 1975 and U.S. 3,671,487 dated June 20, 1972. Other flame retardants are disclosed in U.S. 3,681,281 dated August 1, 1972, U.S. 3,557,053 dated January 19, 1971, U.S. 3,330,771 dated August 20, 1974 and U.K. 1,358,080.
~ 9 ~ 8CH-208~
Special mentlon is made of ~lame retardant aAdi-tives consisting of aromatic carbonate homopolymers having repea-ting units o~ the formula:
(~l)m Rl (x2)r , C - ~_O- C--O -J
wherein Rl and R2 are hydrogen, (lower)alkyl or phenyl, X1 and X~ are bromo or chloro and m and r are from l to 4~ These materials may be prepared by techniques well known to those skilled in the art. Also preferred are aromatic carbonate co-polymers in which from 25 to 75 weight percent of the repeating units comprise chloro- or bromo-substituted dihydric phenol, glycol or dicarboxylic acid units~ See, e.g~, A.D. Wambach, UOS~ 3,915,926, above-mentioned.
An especially preferred flame retardant agent will comprise a 50:50 aromatic carbonate copolymer of -tetrabromo-bisphenol-A and bisphenol-A in combination with an organic or inorganic antimony containing compound, e.g., antimony oxide, prepared as described in U.S. 3,915,926, Procedure A.
The amount of flame retardant additiva, if used, is not critical to the invention, so long as it i5 present in a minor proportion based on said composition - - major pro-portions will detract from physical properties - ~ but at least sufficient to render the polyes-ter resin non-burning or self-30 ex-tinguishing. Those skilled in the art are well aware that the amount will vary with the nature of the resin and with the efficiency of the additive~ In general, however, the amount ~ ~ ~ 9 7 8CH-2082 oE additive will be from 0.5 to 50 parts by weigh-t per 100 parts of resin.
Other ingredients, such as reinforciny agent~, dyes, pigments, stabilizers, plasticizers, fillers, and the like, can be added.
The ~ollowing examples illustrate the invPntion.
They are set forth as a further description but are not to be construed as limiting the invention thereto.
EXAMPLES l-3 Dry blends of poly(l,4-butylene terephthalate), intrinsic viscosity about 1.05 dl./g., melt viscosit~ about - 6,200 poise, and zinc carbonate are compounded manually under nitrogen in a test tube immersed in a Wood's me-tal bath maintained at a temperature o~ about 240 C. The molten resin ~oams but most of the gas is allowed to escape. After cooling, the glass is broken away leaving a foamed "peg" suitable for evaluation of dripping characteristics. The spatula used for mixing is left protruding from the foamed sample and functions as a handle. The formulations, based on 5 grams total, are shown in Table 1.
TABLE lo Foamed Compositions of poly (1~4-butylene terephthalate) _ _ ~ a~ c~r~n~
Inqredients ~qrams~
poly(l,4-butylene terephthalate) 4.95 4.85 4.75 zinc carbonate ~05 .15 0.25 The dripping behavior o~ the compositions is tested by holding each peg in a flame and making an obsPrvation. The foamed com-position of Example lt made with 1% by weight o~ Zi}lC carbonate,burns and drips, as does the foamed composition of Example 2, made with 3% by weight of zinc carbonate. I-Iowever, the foamed ~ ~ ~ Q 69 7 8CH-2082 composition of Example 3, containing 5~O by weight of zinc car-bonate, burns, but there is no drippingO
EX~MPL_S 4-6 Dry blends of poly(l,4-butylene terephthalate) con-taining a 50:50 copolycarbonate of bisphenol A and tetrabromo-bisph nol A and an-timony oxide as flame retardant agents (See Wambach, U.SO 3,915,926) and zinc carbonate are prepared and foamed in a ~est tube by immersion in a Wood's metal bath at about 290 C. The formulations are summarized in Table 2.
TABLE 2. Foamed Composi~bns of poly (1,4-butylene terephthalate), zinc carbonate and flame re-tardant Inqredients (qrams) poly(l,4-butylene terephthalate) 50:50 aromatic car-bonate copolymer of TBB~* and BPA** I ~4.95 4.85 4.75 antimony oxide J
zinc carbonate .05 .15 .25 .~_ * I'etrabromobisphenol-A
** Bisphenol A
When the Eoamed compositions are held in an open flame, the composition of Example 4 foamed with 1% zinc carbonate is self-extinguishing and dripping behavior is greatly improved; the composition of Example 5 foamed with 2% zinc carbonate is self-: extinguishing with still greater improvement in drip bQhavio.r;
and the foamed compositon of Example 6 is self-extinguishing and the drip .is so much improved that only charred chunks instead of flaming liquid fall off~
9~
The procedure of Example 3 is repeated, substi-tuting
positions comprising a normally Elammab:Le high molecular weight polyester with or without a flame retardant agent, and as a foaming agent, a thermally decompo~3able zinc compound selacted rrom among æinc carbonate, zinc formate and mixtures thereof~
The use of high .molecular weight polyesters in thermoplastic molding compositions is well known to those - skilled in the art. Such polyesters provide compositions with excellent moldability, and molded articles therefrom having a smooth and glossy surface appearance, high strength, stifEness, temperature resistance and othex desirable properties.
With the development of foamed plastics technology, polyesters have enjoyed increasing use in the manufacture of foamed plastic articles. This typically involves the admixture ~ of a "blowing agent", e.g., a thermally decomposable solid 20 or liquid chemical compound, with a thermoplastic polyester resin and the transfer of the resulting foamable mixture to a mold where a foamed ar-ticle is Eormed.
However, in addition to the need for highly efficien-t foaming agents, it is desirable to improve the burning behavior of foamed compositions containing the afore-mentioned polyesters~
The flammability of polyesters has been reduced by using flame retarding agents and such compositions are described in various patents and publications~
It has now been surpri.singly discovered that csrtain æinc compounds are uniquely effective foaming agents~ They also improve the flame retardancy of foamed thermoplastic polyester molding com~ositions. While not wishing to be bourld by ~ ~ 110 ~697 8CH-2082 any theory of the invention, it is believed that the particular zinc compounds decompose at the molding temperature of the polyester resin to libera-te a gas, e~g., carbon dioxide or carbon monoxide, which causes foami.ng, and the production oE
zinc oxide. The latter appears to act as an anti-drip agent.
The additive levels most suitabl.e for the two purposes are about the same. Thus, the use of the zinc compounds in this manner makes possible the fabrication of super.ior ~oamed plastic articles. As an additional benefit, the articles are significantly improved in a key flammability characteristic, i.e., the reduced tendency to drip when near to an open flame.
According to this invention there are provided foamable thermoplastic molding compositions which comprise, in intimate admixture:
(a) a high molecular weight polyester resin; and (b~ a thermally decomposable foaming agent selected from the group consisting oE zinc carbonate, zinc formate and mixtures thereof, 20 said agent being present in an amount at least sufficient to cause foaming in said thermo-plast.ic composition during molding~
The eEfectiveness of zinc carbonate in the present compositions is believed to be due to the fact that it decom~
poses to zinc oxide and carbon dioxide at the molding tempera-ture of polyester resins~ These two products bring about the changes in -the resin that are the basis of the invention - -the carbon dioxide acts as a foaming agent and the zinc oxide appears to act as an agent to retard dripping when the foamed article is near an open ~lame. The zinc carbonate decomposi-tion temperature, about ~40~C. in a melt point capillary, is such that compositions of polyester resins or related materials 8CH 20~2 6~7 containing undecomposed zinc carbonate are accessible. A
valuable application o:E this invention is in the production of foamed polyester resin having the improved behavi.or when near open flames.
The zinc salt which has been found to serve as an e~ficient foaming agent at about the same additive level as for zinc carbonate is zinc formate. Zinc formate is at least as . effective as the carbonate, apparently a:Lso forming zinc oxide in situ, represented as follows:
o Zn(OCH~2 ~ ZnO + 2 CO -~ ~2 In air, zinc ~ormate liberates gas vigorously ak about 280C.
In th~ polyester resin composition melt at moldiny termperatures, the gas causes the foamed composition -to be produced.
In preferred compositions, the foaming agent is present in an amount of at least about 0.5% by weight of (a) and (b), more preferably from about 0.5 to about 5% by weight, based on (a) and (bj combined.
The high molecular weight normally flammable poly-esters used in the present compositions are preferably poly-meric glycol esters of terephthalic acid and isophthalic acids.
They are available commercially or can be prepared by known techniques such as ~y the alcoholysis of esters of the phthalic acid with a ylycol and subsequent polymerization, by heating glycols with the free acids or with halide derivatives thereoE, and similar processes~ These are described in U.S. 2,465,319 dated March 22, 1949 and U.S. 3,047,539 dated July 31, 1962 and elsewhere~
Although the glycol portion of the polyester can con-tain from two to ten carbon atoms, it is preferred that it con-tain from two to four carbon a-toms in the form of linear me-thyl-ene chains.
More preferably, the polyesters will be of the Eamily consisting of high molecular weight, polymeric glycol terephthal-ates or isophthalates having repeating units of the general formula: 1 ~C112)n 0 C ~3/ C --wherein n is a whole number of from two to four t and mixtures of such esters, including copolyesters of terephthalic and isophthalic acids of up to about 30 mole % isophthalic units.
Especially preferred polyesters are poly~ethylene tere-phthalate) and poly(l,4-butylene terephthalate). Special mention is made of the latter because it crystallizes at such a good rate that it may be used for injection molding without the need for nucleating agents or long cycles, as is sometimes necessary with poly(ethylene terephthalate).
Illustratively, the high molecular weight polyester will have an intrinsic viscosity of at least about 0.4 decilit-ers/gram and preferably, at least 0.8 deciliters/gram as measured in a 60:40 phenol/tetrachloroethane mixture at 30C.
In the preferred embodiments, the optional f]ame re-tardant agent can be selected from among materials conventionally employed for such purposes. Illustrative flame retardant addi-tives are disclosed in U.S. 3,833,685 dated Septem~er 3, 1974, U.S. 3,334,154 dated August 1, 1967, U.S. 3,915,926 dated October 28, 1975 and U.S. 3,671,487 dated June 20, 1972. Other flame retardants are disclosed in U.S. 3,681,281 dated August 1, 1972, U.S. 3,557,053 dated January 19, 1971, U.S. 3,330,771 dated August 20, 1974 and U.K. 1,358,080.
~ 9 ~ 8CH-208~
Special mentlon is made of ~lame retardant aAdi-tives consisting of aromatic carbonate homopolymers having repea-ting units o~ the formula:
(~l)m Rl (x2)r , C - ~_O- C--O -J
wherein Rl and R2 are hydrogen, (lower)alkyl or phenyl, X1 and X~ are bromo or chloro and m and r are from l to 4~ These materials may be prepared by techniques well known to those skilled in the art. Also preferred are aromatic carbonate co-polymers in which from 25 to 75 weight percent of the repeating units comprise chloro- or bromo-substituted dihydric phenol, glycol or dicarboxylic acid units~ See, e.g~, A.D. Wambach, UOS~ 3,915,926, above-mentioned.
An especially preferred flame retardant agent will comprise a 50:50 aromatic carbonate copolymer of -tetrabromo-bisphenol-A and bisphenol-A in combination with an organic or inorganic antimony containing compound, e.g., antimony oxide, prepared as described in U.S. 3,915,926, Procedure A.
The amount of flame retardant additiva, if used, is not critical to the invention, so long as it i5 present in a minor proportion based on said composition - - major pro-portions will detract from physical properties - ~ but at least sufficient to render the polyes-ter resin non-burning or self-30 ex-tinguishing. Those skilled in the art are well aware that the amount will vary with the nature of the resin and with the efficiency of the additive~ In general, however, the amount ~ ~ ~ 9 7 8CH-2082 oE additive will be from 0.5 to 50 parts by weigh-t per 100 parts of resin.
Other ingredients, such as reinforciny agent~, dyes, pigments, stabilizers, plasticizers, fillers, and the like, can be added.
The ~ollowing examples illustrate the invPntion.
They are set forth as a further description but are not to be construed as limiting the invention thereto.
EXAMPLES l-3 Dry blends of poly(l,4-butylene terephthalate), intrinsic viscosity about 1.05 dl./g., melt viscosit~ about - 6,200 poise, and zinc carbonate are compounded manually under nitrogen in a test tube immersed in a Wood's me-tal bath maintained at a temperature o~ about 240 C. The molten resin ~oams but most of the gas is allowed to escape. After cooling, the glass is broken away leaving a foamed "peg" suitable for evaluation of dripping characteristics. The spatula used for mixing is left protruding from the foamed sample and functions as a handle. The formulations, based on 5 grams total, are shown in Table 1.
TABLE lo Foamed Compositions of poly (1~4-butylene terephthalate) _ _ ~ a~ c~r~n~
Inqredients ~qrams~
poly(l,4-butylene terephthalate) 4.95 4.85 4.75 zinc carbonate ~05 .15 0.25 The dripping behavior o~ the compositions is tested by holding each peg in a flame and making an obsPrvation. The foamed com-position of Example lt made with 1% by weight o~ Zi}lC carbonate,burns and drips, as does the foamed composition of Example 2, made with 3% by weight of zinc carbonate. I-Iowever, the foamed ~ ~ ~ Q 69 7 8CH-2082 composition of Example 3, containing 5~O by weight of zinc car-bonate, burns, but there is no drippingO
EX~MPL_S 4-6 Dry blends of poly(l,4-butylene terephthalate) con-taining a 50:50 copolycarbonate of bisphenol A and tetrabromo-bisph nol A and an-timony oxide as flame retardant agents (See Wambach, U.SO 3,915,926) and zinc carbonate are prepared and foamed in a ~est tube by immersion in a Wood's metal bath at about 290 C. The formulations are summarized in Table 2.
TABLE 2. Foamed Composi~bns of poly (1,4-butylene terephthalate), zinc carbonate and flame re-tardant Inqredients (qrams) poly(l,4-butylene terephthalate) 50:50 aromatic car-bonate copolymer of TBB~* and BPA** I ~4.95 4.85 4.75 antimony oxide J
zinc carbonate .05 .15 .25 .~_ * I'etrabromobisphenol-A
** Bisphenol A
When the Eoamed compositions are held in an open flame, the composition of Example 4 foamed with 1% zinc carbonate is self-extinguishing and dripping behavior is greatly improved; the composition of Example 5 foamed with 2% zinc carbonate is self-: extinguishing with still greater improvement in drip bQhavio.r;
and the foamed compositon of Example 6 is self-extinguishing and the drip .is so much improved that only charred chunks instead of flaming liquid fall off~
9~
The procedure of Example 3 is repeated, substi-tuting
2% by weight of æinc formate for 5% by weight of zinc carbonate.
An efficiently foamed composition is obtained. When exposed to an open flame the foamed resin burns, but there is no drip-ping. In contrast, a sample of the polyester itself burns and drips.
EX~MPLE 8 ~ composi-tion according to this invention is made by forming an intimate blend of 2% by weight of zinc carbonate and 98% by weight of poly(l,4-butylene-te~ephthalate). Using a Beloit injection foam molding machine, large foamad parts of ;~ excellent appearance are produced a-t 490 F. The parts are 1/4 -inch in thickness. Saw~d pieces show a good foam structure.
The pieces do not drip resin w~en ignited in an open flame.
Obviously, okher variations are possible in the light of the above description. It is to be understood, therefore, that modifications may be made in the compositions disclosed herein which are within the full intended scope of the present invention as defined in the appended claims.
An efficiently foamed composition is obtained. When exposed to an open flame the foamed resin burns, but there is no drip-ping. In contrast, a sample of the polyester itself burns and drips.
EX~MPLE 8 ~ composi-tion according to this invention is made by forming an intimate blend of 2% by weight of zinc carbonate and 98% by weight of poly(l,4-butylene-te~ephthalate). Using a Beloit injection foam molding machine, large foamad parts of ;~ excellent appearance are produced a-t 490 F. The parts are 1/4 -inch in thickness. Saw~d pieces show a good foam structure.
The pieces do not drip resin w~en ignited in an open flame.
Obviously, okher variations are possible in the light of the above description. It is to be understood, therefore, that modifications may be made in the compositions disclosed herein which are within the full intended scope of the present invention as defined in the appended claims.
Claims (7)
1. A foamable thermoplastic molding composition comprising, in intimate admixture:
(a) a high molecular weight linear polyester alone or in combination with a flame retardant agent, and (b) zinc formate in an amount at least sufficient to cause foaming in said thermoplastic composition during molding while retarding dripping of the resin while molten.
(a) a high molecular weight linear polyester alone or in combination with a flame retardant agent, and (b) zinc formate in an amount at least sufficient to cause foaming in said thermoplastic composition during molding while retarding dripping of the resin while molten.
2. A composition as defined in claim 1 wherein the zinc formate is present in an amount of from about 0.5 to about 5% by weight of (a) and (b) combined.
3. A composition as defined in claim 1 wherein said polyester has an intrinsic viscosity of at least about 0.4 deciliters per gram when measured in a solution in a 60:40 mixture of phenol and trichloroethane at 30°C.
4. A composition as defined in claim 3 wherein said polyester has an intrinsic viscosity of at least about 0.8 deciliters per gram when measured in a solution in a 60:40 mixture of phenol and trichloroethane at 30°C.
5. A composition as defined in claim 1 wherein said polyester is selected from the group consisting of polymeric glycol terephthalate and isophthalate esters having repeating units of the formula:
wherein n is a whole number of from 2 to 4, and mixture of such esters.
wherein n is a whole number of from 2 to 4, and mixture of such esters.
6. A composition as defined in claim 5 wherein said polyester is poly(1,4-butylene terephthalate).
7. A composition as defined in claim 1 which also includes a flame retardant amount of a flame retardant agent.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US75354376A | 1976-12-22 | 1976-12-22 | |
| US753,543 | 1976-12-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1100697A true CA1100697A (en) | 1981-05-05 |
Family
ID=25031090
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA292,789A Expired CA1100697A (en) | 1976-12-22 | 1977-12-09 | Foamable thermoplastic polyester compositions |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS5382869A (en) |
| AU (1) | AU510525B2 (en) |
| CA (1) | CA1100697A (en) |
| DE (1) | DE2755910A1 (en) |
| FR (1) | FR2375289A1 (en) |
| GB (1) | GB1567417A (en) |
| MX (1) | MX145963A (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54162622A (en) * | 1978-06-15 | 1979-12-24 | Nissan Motor | Binder for cast sand |
| US4438223A (en) * | 1983-08-22 | 1984-03-20 | Uniroyal, Inc. | Blowing agent composition containing zinc formate and metal salt activator |
| US4687802A (en) * | 1985-02-25 | 1987-08-18 | General Electric Company | Glass fiber reinforced polyester molding compositions containing metal salts |
| US4655962A (en) * | 1986-03-25 | 1987-04-07 | Uniroyal Chemical Company, Inc. | Blowing agent composition |
| US4692475A (en) * | 1986-03-25 | 1987-09-08 | Uniroyal Chemical Company, Inc. | Blowing agent composition |
| US4777188A (en) * | 1986-12-31 | 1988-10-11 | Uniroyal Chemical Company, Inc. | Process for producing foamed elastomeric compositions |
| IT1252223B (en) * | 1991-12-16 | 1995-06-05 | M & G Ricerche Spa | CELLULAR POLYESTER RESINS AND THEIR PREPARATION PROCEDURE |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE789357A (en) * | 1971-09-27 | 1973-03-27 | Hoechst Ag | IMPROVEMENT IN THE MANUFACTURING OF THERMOPLASTIC POLYMERIC FOAMS |
| GB1466427A (en) * | 1974-04-03 | 1977-03-09 | Fisons Ltd | Process for expanding thermoplastic polymers |
-
1977
- 1977-12-09 CA CA292,789A patent/CA1100697A/en not_active Expired
- 1977-12-14 GB GB51929/77A patent/GB1567417A/en not_active Expired
- 1977-12-15 DE DE19772755910 patent/DE2755910A1/en not_active Withdrawn
- 1977-12-20 JP JP15426677A patent/JPS5382869A/en active Pending
- 1977-12-20 FR FR7738373A patent/FR2375289A1/en active Granted
- 1977-12-21 AU AU31840/77A patent/AU510525B2/en not_active Expired
-
1978
- 1978-01-02 MX MX171896A patent/MX145963A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| AU510525B2 (en) | 1980-07-03 |
| MX145963A (en) | 1982-04-26 |
| GB1567417A (en) | 1980-05-14 |
| DE2755910A1 (en) | 1978-07-06 |
| JPS5382869A (en) | 1978-07-21 |
| FR2375289A1 (en) | 1978-07-21 |
| AU3184077A (en) | 1979-06-28 |
| FR2375289B1 (en) | 1985-03-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |