Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-12-15
2003-07-29
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
Reexamination Certificate
active
06599966
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to polycarbonate-polyester compositions having a flow enhancing additive.
BACKGROUND OF THE INVENTION
Polyester resins derived from terephthalic acid and reactive derivatives thereof, such as dimethyl terephthalate, and alkanediols have been known for some time and have become important constituents for moldable compositions. Workpieces molded from such polyester resin compositions, alone, or combined with reinforcements, offer a high degree of surface hardness, solvent resistance, abrasion resistance, and high gloss. More recently, blends of such polyester resins with one or more second resins have become of significant commercial interest because such second resins, carefully selected, can greatly improve impact strength, as well as tensile strength, modulus, dimensional stability and distortion temperature under load in parts molded from such compositions. Such second resins can comprise aromatic polycarbonate resins as described for example, in Kawase et al, U.S. Pat. No. 3,953,539 and related polyester-carbonate and polyarylate resins.
Impact-modified PC/PBT blends are very suitable materials for exterior automotive applications (e.g. as bumpers). A good flowing material during molding is a necessity for that molding cycles while the mechanical properties as impact of the molded part should be excellent in order to pass the application specifications. Improvement of the impact/flow balance cannot be simply done by changing the PC/PBT-ratio or polymer molecular weights or by reducing the impact modifier content. So, the problem to be solved is to increase the flow behavior of an impact modified PC/PBT blend without major effects on ductility.
Hence, it is desirable to increase the flow behavior of an impact modified PC/PBT blend without major effects on ductility.
None of following referenced patents describe the use of lignin-type of compounds or phosphonium sulfonate type of compounds as a flow improver in a blend of PC with PBT, while the other properties as impact and heat resistance stay for the major part the same.
U.S. Pat. No. 4,209,427; GE-Patent filed 1977: flame-retardant polycarbonate composition. This patent describes that the use of lignin or lignosulfonates can be used as a flame-retardant additive. Typical amounts are 0.5-1.0 part per 100 parts PC.
U.S. Pat. No. 4,943,380; Patent from Takemoto Yushi Kabushiki Kaisha, filed 1989: anti-static resin composition with transparency containing phosphonium sulphonate. The use of 0.1-10% of phosphonium sulphonate is described.
U.S. Pat. No. 4,038,258; Patent from DuPont, filed 1976: anti-static composition containing an aliphatic polyester or polyetherester and a phosphonium salt. Polyesters having a Tg<25 C., containing 0.02-35% of a phosphonium salt.
PAJ-08059975 (publ.no.); Patent from Teijin, filed 1994: To obtain a PC, excellent in high temp. stability, melt moldability, hydrolytic resistance, a (phosphonium) sulfonate is added (0.01-500 ppm) during the reaction system to obtain a PC with desired viscosity.
PAJ-07304942; Patent from Mitsubishi Chem.Corp., filed 1994: Blend of PC with 0.1-20 pts. wt phosphonium sulfonate. Mentioned advantages: flowability, mechanical properties, anti-static properties.
PAJ-06089499 and 07292234; Patents from Teijin, filed 1994: Blend of PC (45-93%), polyalkyleneglycol (12-15%) and polyester with groups attached to it (5-40%) in order to get anti-static properties.
PAJ-07188539; Patent from Nippon GII Plast KK, filed 1993: Blend of a specific copolycarbonate (eg based on BPA and resorcinol) with 0.1-10% of a phosphonium sulfonate to get ant-static properties.
PAJ-07165905; Patent from Teijin, filed 1993: Production of stabilized PC-resin by adding a phosphonium sulfonate on and after the completion of a reaction in solution polymerization.
PAJ-07062215 and 05171024; Patents from Mitsubishi Chem. (Kasei) Corp., filed 1993: Blends of 100 pts PC with 0.1-20 pts phosphonium sulfonate and 0.01-3 pts sulfur containing ester compound to get antistatic properties.
PAJ-08092819; Patent from Asahi Chem.Ind.Co., filed 1994: Blend of a polyester copolymerized with 1 mol % isophthalic acid component containing a metal sulfonate group with 0.01-0.3% of P-cpd as viscosity reducing agent. P-cpd is pref. a phosphonium phosphonate.
PAJ-06279658 and 06263855; Patents from Teijin, filed 1993: Modified polyester (polyester-ionomer), synthesized through copolymerization using a phosphonium sulfonate compound.
PAJ-06041408 and -06041407: Patents from Toray Ind., filed 1991: Modified polyester: polyester (eg PET) and incorporated therein 1-30% ester-forming phosphonium sulfonate compound and 1-20% polyalkyleneglycol.
SUMMARY OF THE INVENTION
It has been found that the presence of lignin or phosphonium sulfonate compounds provides highly improved flow properties in a PC/PBT blend, while mechanical and physical properties are remained for a major part.
A molding composition comprising (a) from 10 to 90 weight percent of a polyester resin; (b) from 90 to 10 weight percent of an aromatic polycarbonate, polyarylate, polyester carbonate resin or blend thereof; and (c) a flow improving amount of lignin and/or a compound having a phosphonium sulfonate group.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The phosphonium sulfonate flow enhancing additive is preferably a compound of the formula
(R1-SO3-P(-R3,-R4,-R5,-R6)), wherein R
1
is 1-40 Carbon alkyl or aryl or alkylaryl; and R
3
-R
6
are each H, 1-10 Carbon, alkyl, or aryl. More preferably the phosphonium is a tetrabutylphosphonium dodecylbenzene sulfonate. Typical phosphonium salts include methyltributylphosphonium xylenesulfonate, tetrabutylphosphonium benzenesulfonate, methyltricyclohexylphosphonium xylenesulfonate, benzyltriphenylphosphonium xylenesulfonate, tetraoctylphosphonium phenyl sulfonate, and di(methyltribenzylphosphonium) phenyl sulfonate.
The lignin flow enhancing additive is selected from the group consisting of a lignin, kraft lignin, lignosulfonates and mixtures thereof. As set froth in U.S. Pat. No. 4,209,427, while complete determination of the structure of lignosulfonates apparently as not been achieved, it is known that the basic lignin monomer unit is a substituted phenyl-propane. The lignosulfonates are metallic sulfonate salts prepared commercially from the lignin of sulfite pulp-mill liquors as known in the art. They are described as anionic polyelectrolytes whose molecular weights vary between 1,000 and 20,000. Additionally, the lignosulfonates can be substituted with the substituent consisting of an electron withdrawing radical. Preferably the electron withdrawing radical or substituent is the halo-, nitro-, trihalomethyl or cyano withdrawing radical or mixtures thereof. The electron withdrawing phenomenon, or as it is also referred to as electronegativity, is defined in Basic Principles of Organic Chemistry by Roberts and Caserio, 1964 (pages 185-186), and Physical Organic Chemistry by Jack Hine, McGraw-Hill Book Company, Inc. 1962 (pages 5, 32 and 85-93). Briefly, the electron withdrawing phenomenon is where the radical has a strong affinity for a negative charge, namely electrons, but still remains covalent and does not form an ion. It is considered that a section of polymeric lignosulfonates can have the structure shown in U.S. Pat. No. 4,209,427 wherein M is an alkali or alkaline earth metal in the lignosulfonate.
The lignin additive is preferable present in an amount of 0.1-5 wt %, more preferably in an amount of 0.3-3 wt %, and most preferably in an amount of 0.5-2.0 wt %. The phosphoniun sulfonate compound is preferable present in an amount of 0.03-3 wt %, preferably in an amount of 0.05-1.5 wt %, most preferably in an amount of 0.1-1.0 wt %.
In a preferred molding composition, polycarbonate is present in an amount of 5-95 wt % and the polyester in an amount of 95-5 wt %, more preferably the polycarbonate and polyester are present in an amount of 40-75 wt %, respectively 25-60 wt %. The polycarbonate may be a polycarbonate ester based on bisphenolacetone, and the polyester is
de Wit Gerrti
Penning Jan Paul
General Electric Company
Oppendahl & Larson LLP
Rajguru U. K.
Seidleck James J.
LandOfFree
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