CA1197337A - Impact modified glass/mineral reinforced polyester blends - Google Patents

Impact modified glass/mineral reinforced polyester blends

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Publication number
CA1197337A
CA1197337A CA000418311A CA418311A CA1197337A CA 1197337 A CA1197337 A CA 1197337A CA 000418311 A CA000418311 A CA 000418311A CA 418311 A CA418311 A CA 418311A CA 1197337 A CA1197337 A CA 1197337A
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poly
parts
resin
core
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CA000418311A
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French (fr)
Inventor
Leonard R. Hepp
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General Electric Co
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General Electric Co
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Abstract

IMPACT MODIFIED GLASS/MINERAL REINFORCED
POLYESTER BLENDS
Abstract of the Disclosure The addition of poly(ethylene terephthalate) to core-shell resin impact modified, glass fiber and mica reinforced poly(1,4-butylene terephthalate) compositions provides articles molded therefrom with improved surface gloss, impact strength, flexural modulus, flexural strength and tensile strength. Heat distortion temperatures are elevated if not less than 2.6 nor more than 4 parts by weight of poly(1,butylene terephthalate) resin is present for each 1 part by weight of acrylic resin impact modifier.

Description

733~

- 1 ~ 8CV-3~90 IMPACT MODIFIED GLASS/~INERAL REINFORCED
POLY~ BLENDS
The present invenkion relates to polymeric resin molding compositions. More particularly, it relates to impact modi.fied, glass/mineral-reinforced polyester resin molding compositlons with improved surface appearance and elevated resistance to deflection under load at high temperatures.
.
Backgro'und 'o'f -the'I'nvent'ion It has been found that substitution of up to 20 percent by weight of poly(ethylene terephthalate) (PET) for poly(l,4-butylene terephthalate) (PBT) in glass fiber reinforced, optionally impact modified, molding compositions improves the surface gloss of articles molded therefrom. Such compositions are described and claimed in Fox and Wambach United States Patent No. 3,953,39~, dated April 27, 1976. Such a substitution, however, has a tendency to reduce notched Izod impact strength, flexural modulus, flexural strength and tensile strength. As a result, such glass reinforced PET/PBT blends find most advantageous use when improved surface gloss outweighs the reduction is physical properti.es. It has also been found that compositions with high heat distortion temperatures and resistance to warping during removal from the mold can be produced by reinforcing impack modified PBT with a combina-tion of glass fiber and mica. Such compositions, which tend to have low surEace gloss, are described and claimed by 8CV-3~90 Liberti in Canadian patent application Serial No.330,878 filed June 29, 1979 Gexman Offenlegungsschrift Patent No. 2,931,430 dated July 31, 1980, describes PBT molding compositions, containing PET, impact modified with an acrylic resin and reinforced with glass fiber and mica.
Such composition are disclosed to have high impact strength and stiffness. The ratio of PBT to impact modifier is below 2:1, and the amount of psT used with respect to PET
is generally equal to or lower than 3:2~ In addition, the 10 ratio of combined polyesters to combined reinforcement is generally below 5:4, e.g. 4.5:4.
It has now been discovered that the addition of PET to the impact modified glass fiber and mica reinforced PBT compounds not only improves surface gloss but also 15 it improves notched I~od impact strength, flexural modulus, flexural strength and tensile s-trength. ~urprisingly, if the amount of impact modifier is controlled, based on the PBT content, to not less than 3 nor more than ~ parts by weight of PBT per part by weight of impact modifier, then 20 very beneficial effects on heat distortion resistance can be obtained. Such a modification and the advanta~eous effects are nowhere suggested by the above-mentioned German Offenlegungsschrift.
Description of the Invention According to the present invention, in a thermo-plastic composition comprising:
(a) a polyester composition comprising:
(i) a major proportion of a poly(l,4-butylene terephthalate) resin or a copolyester thereof with a minor amount of an aliphatic or aromatic dicarhoxylic acid or an aliphatic polyol and (ii) a minor proportion of a poly (ethylene terephthalate resin);

~733~ 8CV-3890 (b) an impact improving amount of a core shell resin having; and a rubbery core surrounded by a grafted acrylic shell; and (c) an effective reinforcing amount of a cor~ination comprising approximately equal weights of mica and glass fibers, there is provided the improvement which comprises providing not substantially less than about 2.6 and not substantially more than about 4 parts ~y weight of poly (1,4-butylene terephthalate) resin component (a) (i) per 1 part by weight of said impact improving core shell resin component (b~.
As will be shown hereinafter, the heat distortion temperature (Deflection Temperature Under Load, DTUL, ASTM
(D648) at 264 psi is elevated from 352 F. with a PBT/core shell resin impact modifier weight ratio of 2:1 according to the prior art to 394F. with a PBT/core-shell resin modifier ratio of about 3:1 according to the present discovery. Other properties, especially stif~ness properties are also improved, and melt viscosity, which is of key importance in molding, is drastically reduced.
The poly(l,4-butylene terephthalate) resin will be of high molecular weight. The polyester units can include a minor amount, e.g., from 0.5 to 2~ by weight~ of units derived from aliphatic or aromatic dicarboxylic acids and/or aliphatic polyols, e.g., glycols, i.e., copolyesters. The poly tethylene terephthalate) resin component is disclosed in Whinfield et al U.S. Patent No. 2,465,319. Such polyesters will have mol.ecular weights high enough to be film-and fiber-~ormers. ~11 such polyesters can be made ~ollowiny the teachings of the above-rnentioned patents, and both poly(ethylene terephthalate) and poly(l,4-butylene -terephthalate~ are cornmercially avallable from a number o~ sources.
~llustrati.vely, sufficiently high mo].ecular weight poly(ethylene ter.ephthalate~ resins will have an intrinsic 73;~
BCV~3890 viscosity of a-t least 0.2 and preferably at least about 0.4 deciliters/yram as measured in o-chlorophenol, a 60/
40 phenoltetrachloroethane mixture or a similar solvent at 25-30C. The poly(l,4-butylene -terephthalate) resins will have intrinsic viscosities of at least 0.6 and more preferably 0.8 dl./g., same basis. The upper limit is not critical, but it will generally be about 1.5 dl./g.
Especially preferred poly(ethylene terephthalates) will have an intrinsic viscosity in the range 0.5-1.0; and preferred poly(l,4-butylene -terephthalate) resins will be in the range of 0.9-1.2 dl./g.
Although poly(ethylene terephthalate) and poly (1,4-butylene terephthalate) are known from the Fox and Wambach patent above-mentioned, to be combinable with each other in all proportions, for the purpose of the present invention, a major proportion, e.g., 51 parts by weight up to 99 parts by weight of PBT will be pxesent for correspondingly from 49 to l part of PET as the minor proportion component. In general, however, compositions containing about 2 to 4 parts by weight of PBT per 2 parts by weight of PET will be preferred~ and those containing about 3 parts by weight of PBT per 2 parts by weight of PET will be especially preferred.
The compositions include a reinforcing filler combination of glass fibers, preferably 1/8 in. chopped glass fiber, and mica, preferably phlogopite mica. Like the Liberti application disclosure, and the German Offen. mentioned above, fibrous glass and mica will be used in approximately equal weights, although it is per-missible to vary somewhat, e.g., ln the range of from 40to 60 parts by weight of glass for, correspondingly, 60 to 40 parts by weight of mica.
The amount of reinforcing agent combination present can v~r~ somewhat too, although a preference can be stated 3~ for about 40 parts by weight for each 100 parts by weight of resin, impact mo~lifier and reinforcement, combined. It i5 ~9~3~7 8CV-3890 -to be understood, however, that some la-titude is permissible here, too, e.g., within a range of from about 35 to about 45 parts by weight of reinforcing combination per 100 parts o~ total composition, by weight. The best properties seem to be exhibited in compositions comprising a weight ratio of polyester component (a) to rein~orcing combination (c~ of about 5:4.
Impact modifier (bl comprises a core shell resin of the type generally used with such polyester resi~. These are comm~Mrcially available, one especially preferred being Acryloid KM 330, another being Acryloid KM 653, and a third being Acryloid KM 323B, all sold by Rohm & Haas, Phila., Pa., Suitable such acrylic impact modifiers are also described with methods for their preparation in many cases, in Fromuth et al., U~S. 4,180,494 to Farnham et al date~ December 25, 1979., 4,096,202 dated June 20,19~ and Lane, U.S. 4,03~,013 dated July 5, 1977.
A suitable core shell polymer comprises a two stage interpolymer, the first stage comprising about 50 to g5% by weight of the interpolymer and being polymerized from a monomer system comprising 95 to 99.8 wt. ~ of butyl acrylate, 0.1 to 2.5 wt.% of allyl methacrylate or dial-lyl maleate J and the outer stage comprising methyl methacrylate, about 60 to 100% by weight of(United States Patent No. 4,096,202) Another suitable core shell polymer comprises a core polymerized from a monomer system comprising a diene moner, e.g., or butadiene or isoprene, styrene, methyl methacrylate and divinyl benzene, an intermediate stclge polymerized from styrene, and a shell polymerized from methyl methacrylate and 1,3-butylene glycol diamethy-late.
~ t is crit:ical to the present invention that not less than about 2.6 parts by weight of PBT be used per 1 part by weight of acrylic impact modifier. Otherwise, the DTUL (deflect:ion temperature under load) will be 733~
8CV-3~90 reduced. The upper limit of this ratio is somewhat less critical, but no advantageous results are e~pected if more than about 4 parts by weight of PBT are used for each 1 part by weight of acrylic impact modifier.
The most preferred composition in terms of amounts appears to comprise per 100 parts by weight:
(a) a polyester composition comprising:
(i~ about 30 parts by wei~ht of poly-tl,4-butylene terephthalate) resin;
(ii)about 20 parts by weight of poly-(ethylene terephthalate) resin;
(b~ about 10 parts by weight of an impact improving core shell resin having a rubbery core surrounded by a grafted acrylic shell; and (c~ a combination comprising about 20 parts by weight of reinforcing mica and about 20 parts by weight of reinforcing glass.
The reinforced impact modified polyester combination can be rendered flame retardant wi.th an ef~ective amount of a conventional flame retardant agent. As is well known, flame retardants can be based on elementary red phosphrous compounds, halogen compounds and nitrogen compounds alone or preferably in further combination with synergists, such as antimony compounds. Especially useful are brominated diphenyl ethers and polymeric and oligomeric flame retardant agents compri.sing tetrabromobisphenol-A carbonate units, see, for example Wambach, U.S. 3,833,~85 dated September 3, 1974.
Other ingredients, such as dyes, pigments, drip retardants, and the like can be added for their convention-all~v employed purposes.
~ lhe compos.itions of the invention can be prepared b~ a number of procedures. In one way, the impact modifier and the reinforcemen-t is put into an extrusion compounder w.ith the resinous components to produce molding pellets.
The modifier and reinforcement is dispersed in a matrix r~
~ 8 CV - 3 ~ 3 0 of the resin in the process. In another procedure, the modifier is mixed with the resins and the reinforcements by dry blending then either fluxed on a mill and comminuted, or they are extruded and chopped.
The compositions can be molded in any equipment conventionally used for glass/mineral-filled thermo-plastic compositions, e.g., a Van Dorn type injection molding machine with conventional cylinder temperatures, e.g., 450-525F. and conventional mold temperatures, e.g., 10 140 -160F.
Description of the Preferred Embodiments The rollowing examples illustrate the invention.
They are set forth as a further description but are not 5 to be construed as limiting the invention thereto.

Dry blends of poly(l,4-butylene terephthalate) resin, poly(ethylene terephthalate~ resin, core-shell resin impact modifier, glass, mica and mold release /
stabilizex are compounded and extruded at 540F. in an extruder. The extrudate is pelleti~ed and injection molded at 490 F. (mold temperatuxe 150 F). A control is analyzed and run for comparision purposes. The samples for warpage test comprise 1/1~ X 4 circular discs, edge, gated, injection molded at 200 F. Shrinkage ll ll is measured on an 1/8 X 4 circular disc, in the machine direction (first value~, and in the transverse direction (second value~. The formulations and physical properties are shown in Table 1:

il97337 8CV-3890 Table 1. Compositions Comprising Polyes-ters, Impact Modified and Reinforced with Glass/Mica Example 1 A
Composition tparts by weight~
Poly(1,4-butylene terephthalatel 29.85 (26 5) Poly(ethylene terephthalate1 20. 0 (20.2) 5 Core-shell impact modifier lOr 0 (13.3) Glass fibers 20. 0 (20.0) Micae 20. 0 (20.0) Mold release/stabilizers (to make lOQ) 10 Properties Heat Distortion (DTUL) 264 psi F 394 352 Warpage, R.T.~ mm. 0 2 annealed a 350 F. for 30 min., mm. 5.0 12.3 Notched I~od Impact, ft.]bs./in. 1.6 1 .8 15 Unnotched Izod Impact, ft.lbs./in. 8.7 10. 2 Flexural Strength, psi 22,200 19,600 Flexural Modulus, psi 1,172,000 1,100,000 Tensile strength, psi 13,120 11,400 Spiral flo~ (in./600 psi) 6.15 5.6 20 Melt viscosity, pellet-poise(510 F.) 16,780 39,886 Specific Gravity 1.613 1.607 Shrink, mils./in. 5.1-5.9 5-6 *Control tbY analysis GAF Corp. 7443R; See also Germ Offen. 2,931,430, ~an~ 18, 1980) 5 a Intrinsic viscosity, 0.85 dl./y., measured at 30C.
in 60/4Q w~ phenol-tetrachloroethane b Goodyear VituE 59t)0A
c Rohm & Haas ~cryloid KM330, rubbery acrylic core, thermoplastic acrylic she]l cl 1/8" chopped strand ~L~.~tA~
~ 8c~-3890 -- ~3 --The excellent resistance to heat distortion and the generally improved properties, as well as easier mold flow. provided by the present invention are seen in compar;ng Example 1 which uses about 3 parts of PBT
per 1 part of core-shell modifier with comparative Example ~*, which uses about 2 parts of PBT per 1 part of core-shell modifier.
To provide more data on a possible upper limit in the ratio of PBT to core-shell modifier/ the formulation of Example 1 is modified b~ replacing one half of the core-shell modifier wit~ an equal weight of a non-core-shell impact modifier (Hytrel resin-DuPont a copolyester of butylene oxide and butanediol with terephthalic acid).
This produces a composition with about 6 parts by weight of PBT per 1 part by wei~ht of core-shell modifier and, while generally excellent, physical properties were re-tained~ the heat distorition temperature was lower, 383 F., instead of 394 F. for Example 1.
\

733~7 8CV-3890 Compositions are pxepared, molded and tested by the general procedures set forth above. The formulations and physical properties are shown in Table 2:
Table 2: Polyester Compositions Impact Modified and Reinforced Exa~ple 2 3 Composition (parts by weight) Poly (1,4-butylene terephthalate)27.3 26.5 Poly (ethylene terephthalate~ 20.0 15 10 Core-shell impact modlfier(~ 10 --Core-shell impact modifier(b) (ii~ __ 10 Glass fibers 20 20 Mica 20 20 Flame retardant additive(dl -- 8.5 15 Mold release/stabilizer ~el (il combination . -- 0.7 Stabilizer combination(e) (1l~ 2.0 __ Properties Distortion Temperature at 264 psi, F. --372 20 Warpage, room temperature, mm. -- 1.0 annealed at 350F.,30 min.,mm. - 6.7 Notched Izod impact, ft.lbs.~in. 1.6 1.5 Unnotched Izod impact, ft.lbs./in.8~2 7.8 Flexural strength (103 psi)17.3 20.8 Flexural modulus (10 psi)107.7 120.1 Tensile strength (10 psi~10.2 12.8 Flammability, UL Bull. ~4 -- V-0 (bl (i) Acryloid KM 653,Rohn & Haas,butadiene core,acrylate shell (b) (iil Acrylo:id KM330, Rohm & Haas, acrylate core, acryl~te shell (dl decabromodi}?henyl ether 4.5;antimony oxide 4.0 (pbw) (el (il P~ -18, pentaerythritol tetrastearate 0.2:Naugard P, O.5 (pb~
(el (iil Seeno~ A125, 1. 33: Topanol CA, .33: Naugard 445, 0.33 (pbw) Example 2 provides excellent workpieces using a core-shell polymer having a polymerized diene rubbery core. Example 3 provides excellent woxkpieces with flame retardant properties, the impact modifier having a polymerized acrylate monomer rubbery core.
From the foregoing it is seen that the present invention provides compositions with many advantages over those exhibited by the prior art, including samples available from commercial sources in addition to assignee herein.
Obviously, other modifications and variations of the present invention are possible in the light of the above teachings. It is, therefore,to be understood that changes may be made in the particular embodiments described which are within the scope of the invention as defined in the appended claims.

Claims (10)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. In a thermoplastic composition comprising (a) a polyester composition comprising:
(i) a major proportion of a poly-(1,4-butylene terephthalate) resin or a copolyester thereof with a minor amount of an aliphatic or aromatic dicarboxylic acid or an aliphatic polyol and (ii) a minor proportion of a poly(ethylene terephthalate resin);
(b) an impact improving amount of a core-shell resin having a rubbery core surrounded by a grafted acrylic shell; and (c) an effective reinforcing amount of a combination comprising approximately equal weights of mica and glass fibers, the improvement which comprises providing not substantially less than about 2.6 and not substantially more than about 4 parts by weight of poly-(1,4-butylene terephthalate) resin component (a) (i) per 1 part by weight of said impact improving acrylic resin component (b).
2. A composition as defined in Claim 1 which comprises about 3 parts by weight of poly(1,4-butylene terephthalate) component (a) (i) per 1 part by weight of impact improving core-shell resin component (b).
3. A composition as defined in Claim 1 comprising about 3 parts by weight of poly(1,4-butylene terephthalate) resin component (a) (i) per 2 parts by weight of poly (ethylene terephthalate) resin component (a) (ii).
4. A composition as defined in Claim 1 comprising about 5 parts by weight of polyester composition (a) per 4 parts by weight of reinforcing combination (c).
5. A composition as defined in Claim 1 wherein said core shell, resin comprises a rubbery core of poly-merized acrylate monomer and an outer shell of polymerized
Claim 5 Cont'd acrylate monomer,
6. A composition as defined in Claim 1 wherein said core shell resin comprises a rubbery core of poly-merized diene monomer and an outer shell of polymerized acrylate monomer.
7. A thermoplastic comprising per 100 parts by weight (a) a polyester composition comprising:
(i) about 30 parts by weight of poly (1,4-butylene terephthalate) resin;
(ii) about 20 parts by weight of poly-(ethylene terephthalate) resin;
(b) about 10 parts by weight of an impact improving amount of a core-shell resin having a rubbery core surrounded by a grafted acrylic shell; and (c) a combination comprising about 20 parts by weight of reinforcing mica and about 20 parts by weight of reinforcing glass.
8. A composition as defined in claim 6 wherein said core shell resin comprises a rubbery core of poly-merized acrylate monomer and an outer shell of polymerized acrylate monomer.
9. A composition as defined in claim 6 wherein said core shell resin comprises a rubbery core of polymerized diene monomer and an outer shell of polymerized acrylate monomer.
10. A composition as defined in claim 1 which also includes a small, effective amount of a flame retardant agent.
CA000418311A 1982-12-22 1982-12-22 Impact modified glass/mineral reinforced polyester blends Expired CA1197337A (en)

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CA000418311A CA1197337A (en) 1982-12-22 1982-12-22 Impact modified glass/mineral reinforced polyester blends

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Application Number Priority Date Filing Date Title
CA000418311A CA1197337A (en) 1982-12-22 1982-12-22 Impact modified glass/mineral reinforced polyester blends

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CA1197337A true CA1197337A (en) 1985-11-26

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