IL45398A - Polyalkylene terephthalate molding resin composition and process for the preparation thereof - Google Patents

Description

RESIN PROCESSES FOB THE PREPARATION THEREOF Field of the This invention relates to a molding resin of improved and to a method of producing The invention is directed to a molding resin of improved color and physical properties comprising an intimate blend of polypropylene terephthalate or polybutylene terephthalate flame with or without a reinforcing filler and other additives such as lubricating nucleating wherein at least 2 percent based on the weight of said polymer is present in powdered the particles are sufficiently small as to pass through a 30 mesh The improved uniformity of the instant compositions yields significantly greater physical property retention and lower color variability than those molded compositions of similar ilk produced without the powdered resin Description of the Prior Art Recent investigations with polypropylene terephthalate and polybutylene terephthalate molding resins have found them to be surprisingly superior to polyethylene terephthalate in many important processing and performance For polypropylene terephthalate and polybutylene terephthalate can be molded and otherwise processed at lower temperatures and have a significantly shorter cycle time in the and of a special the presence of a nucl In as pointed agents internal mold release agents are added to polypropylene terephthalate and polybutylene terephthalate molding there results a marked decrease in the surface the glossy surface finish on products is rendered streaky and As a direct these polypropylene terephthalate and polybutylene terephthalate resins which were first disclosed along with polyethylene terephthalate in Patent to Whinfield and free of nucleating agents internal mold release additives have been found to solve processing problems long associated with ethylene terephthalate and by those skilled in the to be equally associated with all polyalkylene Equally these molding resins present a noticeably improved balance of performance properties which those skilled in the witness the extensive use of ethylene terephthalate molding resins to the almost total exclusion of other polyalkylene did not believe to the superior processing requirements and physical properties of polypropylene terephthalate and polybutylene terephthalate molding resins make them more commercially with a wider area of applicability than polyethylene These molding resins have one considerable drawback they are the production of grade polypropylene polybutylene resins which are is of Molded of polyalkylene tereph are required to be for many Typical of such use is housings for electrical equipment and other electrical parts for these articles must not be ignited by sparks or heat generated by or in the electrical In order to provide a polypropylene terephthalate polybutylene terephthalate resin a wide variety of flame retardant additi es have been developed and in order to eliminate dripping of flaming quite often reinforcing agents such as asbestos are A severe drawback to the use of asbestos fiber is that it tends to agglomerate forms balls or nodules in the presence of a flame retarded composition resulting in significantly lowered physical properties and commercially unacceptable surface uniformity and SUMMARY OF INVENTION It is an object of the present invention to provide polyalkylene terephthalate molding specifically propylene terephthalate and polybutylene with intrinsic viscosities in the range of from about to about deciliters per gram having properties and characteristics via the incorporation of asbestos fibers improving physical characteristics and desirable surfaces and color un mination of the asbestos clumping in polyalkylene terephthalate resin is by ensuring that at least percent of the resin based on the weight of polyraer in the compos ition is in powder the powdered resin will pass through a 30 The improved and dispersion obtained realizes significant not only in color and surface characteristics but physical properties as AILED DESCRIPTION OF INVENTION The base of the resins of this invention is a polyalkylene terephthalate polymer selected from the group consisting of polypropylene terephthalate and polybutylene These polymers which are of the general type described in Patent to Whinfield and can be produced from the reaction product of a dibasic such as terephthalic acid or a dialkyl ester of terephthalic acid dimethyl and diols having 3 and 4 carbon Suitable diols include 1 1 2 and the In the productions of the polymers used in this polypropylene or polybutylene the appropriate bis terephthalate is produced as the The bis terephthalate can b prepared by reacting the dialkyl ester of terephthalic carbon with abovt two of the described It is preferred to use higher proportions of the in cess of moles of the per mole of the since by using such the initial transcsterification is caused to take place more rapidly and The reaction for the esterificaticn is under conditions of elevated temperatures and subatmospheric or superatmospheric the desired temperatures of the reaction can range from about the boiling temperature of the reaction mixture to as high as if After the polymer base is other additives for appearance and property improvements can be incorporated into the molding resins of this invention such as plasticizers hardeners and the like by intimately blending by either dry blending or melt blending in heated rolls or other types of As mentioned these new resins have one deleterious property they are flammable when drip a significant quantity of flaming There are two widely recognized methods for determining the burning characteristics of thermoplastic One is the the Limiting Oxygen Index text and the other is a vertical burning test for classifying materials or designed by the The 94 vertical burning test procedure by the Underwriter s for determining whether or not a material is involves at one a specimen 5 inches in length by inch in width in either inch or inch by a with the longest dimension being The lower end of the specimen is 12 inches above a horizontal layer of dry absorbent surgical A Eunsen burner having a inch diameter tube and a blue flame inch in height is placed under the suspended sample so that the bottom of the sample is inch above the top of the burner The test flame is allowed to remain for 10 and the duration of flaming or glowing combustion of the specimen is If flaming or glowing combustion of the specimen ceases within 30 seconds after removal of the test it is again placed under the specimen for 10 seconds immediately after flaming or glowing combustion of the specimen If the test flame persists longer than 10 seconds but not longer than 30 seconds for materials intended to be classified or not longer than 60 seconds for materials intended to be classified a second set of specimens is to be further The second set is to be tested as above except that dry absorbent surgical cotton is to applied to the glow after 10 seconds from the second removal of test for materials to be classified and after 30 seconds from the second removal of the test flame for materials to be Materials classified sh have any which burn h for seconds after each application of the test Not t a cor t e s for of 5 Not have any which burn with flaming or glowing combustion up to the holding Not have any specimens which drip flaming particles which ignite the dry absorbent surgical cotton located 12 inches below the test Not have any specimens with glow beyond 30 seconds after the second removal of test Not have any specimens with glow beyond 10 seconds after second removal of test flame that ignites dry absorbent surgical cotton General flame retardancy of the polyalkylene sphthalate compounds is achieved by addition of additives well known in the prior art such as those described in Israel Patent Application Sorial on Serial is on Juno which assigned to the same assignee as is the instant Patent With an unfilled the flame retardant additive preferably should be an aromatic ining compound stable at for melt processing the polyalkylene terephthalate and capable of decomposing at conibustion tem eratures of the ol alk lene tere hthalate of antimony whe in the ratio of available metal in the to bromine ranges from about to and weight percent of said compound and said aromatic compound flame retardants based on the total weight of the composition ranges from about to about Wherein the composition contains a reinforcing the flame retardant additive preferably should be an aromatic halide stable at temperatures necessary for melt processing of the polyalkylene terephthalate and capable of decomposing at combustion temperatures of the polyalkylene and a said metal selected from the group consisting of bismuth and wherein the weight ratio of available halide in the aromatic halide to the available metal in the compound ranges from about to about The flame retardant additives should be present in the range of from about 1 to about 30 weight percent based on the total Specifically preferred flame retardant compounds are the pentabromotoluene tetrachlorophthalic tetrabromob phenyl tetrachlorobiphenyl l 3 l 2 2 4 bis di pro dichloro propane and the synergistic flame retarding effect is realized when these compounds are admixed with antimony and bismuth containing preferably the oxides of these group Vb metals and most preferably with antimony As mentioned if reinforcing agents can be blended with the polymer or with the monomers in the polymerization reaction so long as the polymerization reaction is not The type of fillers which can be used include among others glass fibers or continuous acicular calcium cellulosic cotton fabric synthetic metallic powders and the like mixtures The amount of reinforcing filler range from about 2 to about 80 weight from about 5 to about 60 weight percent based on the total molding The range of intrinsic viscosity of the polypropylene terephthalate and polybutylene terephthalate molding resins should be between about to about deciliters per gram with the preferred range being between about to about deciliters per as measured with an 8 percent Stabilizers can also bo added to the stability of the In such a the resin is admixed with from about to about weight percent based on the total weight of the composition and preferably about to about weight percent of a substituted or unsubsti tuted alkyl ne bis fatty acid The grouping can contain from 2 to 12 carbon preferably from 2 to 6 carbon atoms and the fatty acid grouping can contain 2 to 30 carbon atoms preferably 12 to 18 carbon One of the more preferred substituted groupings upon the fatty acid is a hindered phenol for antioxidant The specifically preferred compounds for use in the instant invention are ethylene bis hexene bis lauramide and ethylene ditertiarybutyl 4 hydroxy These and additional stabilizer systems are described in is herein incorporated by reference and assigned to the same assignee as that of the instant To effectively eliminate dripping and thereby ensure an asbestos is to the flame retarded composition at from about to about 50 weight percent based on the weight of the total preferably from about to about 30 weight EXAMPLE I grams of dimethyl and grams of butanediol are mixed together with an appropriate catalyst such zinc raony or The is increased to 200 BO by weight of the methanol has been Vacuum is applied and the temperature is raised to When the resin composition reaches desired viscosity the vacuum is At this time if the flame retardants are to be added they may be admixed under The mass is then usually mixed for 5 to 10 minutes and the resultant polymer discharged and chipped in the usual the glass fiber is to be added to the the fibers are blended for 1 minute melting the polybutylene and then extrusion blended by force feeding through a 1 inch single screw extruder with a stranded The temperatures of the extruder and die range from The strands are ground in a milling type machine to pass through a large screen mesh or Examples I PBT Fiberglass Antimony Asbestos Powdered τ diphen grams N lbs grams G II 1080 630 0 N III 15 1080 630 0 N IV 1080 1080 630 0 Yes V 15 1080 1080 630 0 VI 15 1080 1080 630 No VII 1080 630 No Intrinsic Viscosity percent passes through a 30 mesh screen 61 II illustrates that a containing merely PBT antimony trioxida and asbestos does not show any clumping tendencies at all and as illustrated in Example III even when glass fiber is added to this resin composition there still is no tendency to In the resin composition of Example IV very serious clumping was realized by the mere addition of Example V which is exactly the same as Example IV with the addition of glass fibers also showed this very serious clumping phenomenon caused by the retardant The VI and VII examples illustrate the compositions of the instant invention in that a portion of the polybutylene terephthalate is added in powdered form which effectively eliminates the clumping and realizes a resin composition of extremely high the compositions akin to Example VI with the powdered resin added even the glass fiber that with merely asbestos and the flame retardant additive also exhibit no tendency whatsoever toward When other flame retardant compounds such as tetrabromo hthalic were utilized in lieu of the decabromobiphenyl ether in the above resin composition Examples IV and V severe clumping was realized which subsequently was effectively eliminated via the of about weight percent of the powdered PBT in place of the chi substituted for the PB in above As this invention be embodied in several forms without departing from the spirit or central characters the present are illustrative and not The scope of the invention as defined by the claims rather by the description preceding them and all embodiments which fall within the meaning and range of equivalency of the claims intended to be embraced by those insufficientOCRQuality

Claims (28)

ΚΖΓϊ,Γ ΐ:· CLATISD IS:

1. An improved polyalkylene terephthalate folding re.in composition of signally enhanced uniformity and surface characteristics comprising an intimate blend of a. polyalkylene terephthalate selected from the group consisting cf polypropylene terephthalate and pol butylene terephthalate, the polyalkylene terephthalate having an intrinsic viscosity in the range of from about 0.75 to about 1.5 deciliters per gram; flame retardant additive; and asbestos wherein the improvement comprises having at least 2 percent said polyalkylene terephthalate based on the weight of said resin present as a pov/der sufficiently small that it will pass through a 30 mesh screen.

2. The improved resin composition of claim 1 wherein the asbestos is present in the range of from about 0.2 to about 50 weight percent based on the total composition.

3. The improved resin composition of claim 1 wherein the flame retardant additive is present in the range of from about 1 to about 30 weight percent based on the total composition.

4. The improved resin composition of claim 3 wherein the flame retardant additive comprises an aromatic bromine-containing compound stable at temperatures necessary for melt processing the polyalkylene terephthalate and capable cf decomposing at combustion temperatures of the polyalkylene terephthalate, avid a metal-containing compound, said metal selected from the group consisting of arsenic, antimony and bismuth, wherein the mole ratio of available metal in the metal-co raining compound to from about 1:2 to about 1:4 and the weight percent of said metal-containing compound and said aromatic bromine-containing compound f3 ame retardants based on the total weight of the composition ranges from about 0.5 to about 17.5 percent.

5. The improved resin composition of claim 1 comprising additionally a reinforcing filler.

6. The improved resin composition of claim 5 wherein the reinforcing filler is present in the range of from about 2 to about 80 weight percent based on the total composition.

7. The improved flame retardant resin composition of claim 3 comprising additionally from about 2 to about 80 percent based on the total composition of a reinforcing filler.

8. The improved resin composition of claim 7 wherein the flame retardant additive is an aromatic halide stable at temperatures necessary for melt processing of the polyalkylene terephthalate and capable, of decomposing at combustion temperatures of the polyalkylene terephthalate, and a metal-containing compound, said metal selected from the group consisting of arsenic, antimony, bismuth and phosphorous, wherein the weight ratio of available halide in the aromatic halide to the available metal in the metal-containing compound ranges from about 0.3 to about 4.

9. The improved resin composition of claim 1 comprising additionally a. substituted or unsubstituted alkylene bis fatty acid amide.

10. The improved resin composition of claim S her in in the alkyler.e bis fatty acid amide, the alk lene group from 2 to 12 c rbon atoms and the fatty acid group has from 2 to 30 carbon atoms and the fatty acid amide is present from the range of from about 0.01 to about 1.0.

11. The improved resin composition of claim 10 wherein the substituted or unsubstituted alkylene bis fatty acid amide is ethylene bis stearamide or hexene bis lauramide .

12. The improved resin composition of claim 7 wherein the reinforcing filler is glass fiber.

13. The improved resin composition of claim 7 wherein the reinforcing filler is acicular calcium metasilicate .

14. The improved resin compsoition of claim 7 wherein the reinforcing filler comprises a mixture of glass fiber and acicular calcium metasilicate.

15. An improved process for preparing a polyalkylene terephthalate molding resin composition of signally enhanced uniformity and surface characteristics comprising intimately blending a polyalkylene terephthalate selected from the group consisting of polypropylene terephthalate and polybutylene terephthalate, the polyalkylene terephthalate having an intrinsic viscosity in the range of from about 0.75 to about 1.5 deciliters per gram; a flame retardant additive; and asbestos wherein the improvement comprises intimately blending at least 2 percent of said polyalkylene terephthalate based on the weight of said resin present as- a powder sufficiently small that it will pass through a 30 mesh screen. -1

16. The improved process of claim 3 whs rein the asbestos is present in the range of from about 0.2 to about 50 weight percent based on the total composition.

17. The improved process of claim 15 wherein the flame retardant additive is present in the range of from about 1 to about 30 weight percent based on the total composition .

18. The improved process of claim 17 wherein the flame retardant additive comprises an aromatic bromine-containing compound stable at temperatures necessary for melt processing the polyalkylene terephthalate and capable of decomposing at combustion temperatures of the polyalkylene terephthalate, and a metal-containing compound, said metal selected from the group consisting of arsenic, antimony and bismuth, wherein the mole ratio of available metal in the metal-containing compound to available bromine ranges from about 1:2 to about 1:4 and the weight percent of said metal-containing compound and said aromatic bromine-containing compound flame retardants based on the total weight of the composition ranges from about 0.5 to about 17.5 percent.

19. The improved process of claim 15 comprising additionally blending a reinforcing filler.

20. The improved process of claim 19 wherein the reinforcing filler is present in the range of from about 2 to about 30 weight percent based on the total composition.

21. The improved process of claim 17 comprising additionall blendin from about 2 to about 80 ercent based on the total composition of a reinforcing filler.

22. The improved proc ss of claim 21 wherein the flame retardant additive is an aromatic halide stable at temperatures necessary for melt processing of the polyalkylene terephthalate and capable of decomposing at combustion tem eratures of the polyalkylene terephthalate, and a metal-containing compound, said metal selected from the group consisting of arsenic, antimony, bismuth and phosphorous, wherein the weight ratio of available halide in the aromatic halide to the available metal in the metal-containing compound ranges from about 0.3 to about 4.

23. The improved process of claim 15 comprising additionally blending a substituted or unsubstituted alkylene bis fatty acid amide .

24. The improved process of claim 23 wherein in the alkylene bis fatty acid amide, the alkylene group UUG from 2 to 12 carbon atoms and the fatty acid group has from 2 to 30 carbon atoms and the fatty acid amide is present from the range of from about 0.01 to about 1.0.

25. The improved process of claim 24 wherein the substituted or unsubstituted alkylene bis fatty acid amide is ethylene bis stearamide or hexene bis lau amide.

26. The improved process of claim 21 wherein the reinforcing filler is glass fiber.

27. The improved process of claim 21 wherein the reinforcing filler is acicular calcium metasilicate.

28. The im roved process of claim 21 wherein the reinforcing filler comprises a mixture of glass fiber and acicular calcium metasilicate.