Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
1999-11-01
2001-07-24
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C528S196000
Reexamination Certificate
active
06265527
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for making polyester carbonates. More particularly, the present invention relates to a melt condensation polymerization method involving the pre-reaction of a carbonic acid diester and catalyst with a diacid followed by the reaction of an aromatic dihydroxy compound with the reacted pre-reaction mixture.
Polyester carbonates and methods for their preparation have been studied extensively throughout the years. Polyester carbonates are thermoplastic resins that are clear and have high impact resistance. Due to their optical clarity and physical properties, polyester carbonates are used extensively in injection molding, applications. The synthetic methods commonly used to make polyester carbonates are interfacial polymerization and melt condensation polymerization.
Interfacial polymerization is a well-known process. Fontana et al., U.S. Pat. No. 4,983,706, discuss the reaction of an aromatic dihydroxy compound such as bisphenol-A with phosgene and a diacid. The diacid is incorporated into the reaction mixture to produce a polyester carbonate with melt flow such that the polyester carbonate is suitable for purposes of injection molding. Melt flow can be described in terms of viscosity. Although the polyester carbonate produced by the interfacial method provides excellent viscosity for injection molding, purposes, particulate contamination is often a problem. Additionally, the interfacial method uses a hazardous chemical, phosgene, and an environmentally hazardous chlorinated solvent.
Melt condensation polymerization is a known synthetic process which often results in less particulates found in the polymer compared to the interfacial method. Although melt condensation polymerization does not involve hazardous chemicals, the polyester carbonates made by the melt condensation polymerization process often do not have the flow properties of polyester carbonate made by the interfacial method.
In order to improve the flow properties of polyester carbonates made by the melt condensation polymerization process, different methods have been studied. Sakashita et al. (Japanese Patent No. Hei 4[1992]-345616) discuss a method for preparing polyester carbonates which incorporates aliphatic diacids directly into the polyester carbonate using a melt polymerization process. This method is only concerned with polyester carbonates which contain the aromatic dihydroxy compound, 2,2,2′, 2′-tetrahydro-3,3,3′, 3′-tetramethyl- 1,1′-spirobi[1H-indene]-6,6′-diol, commonly known as SBI. The melt condensation polymerization method of Sakashita et al. adds the aliphatic diacid, aromatic dihydroxy compounds and catalysts in a one-step reaction.
Methods continue to be sought to prepare high quality polyester carbonates which can be used for injection molding purposes using the melt condensation polymerization process.
BRIEF SUMMARY OF THE INVENTION
The present invention provides a melt condensation polymerization process for preparing polyester carbonates. The process involves the steps of:
(I) pre-reacting a carbonic acid diester and catalyst with a diacid; and
(II) reacting at least one aromatic dihydroxy compound with the reacted pre-reaction mixture.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a melt condensation polymerization process for preparing polyester carbonates which involves the pre-reaction of carbonic acid diester, catalyst and a diacid subsequently followed by a reaction of at least one aromatic dihydroxy compound with the reacted pre-reaction mixture. Melt condensation polymerization has been found to be an effective process for the formation of polyester carbonates.
In one embodiment, the composition of the present invention comprises a polyester carbonate comprising structural units of the formula I
wherein D is a divalent aromatic radical; and repeating or recurring units of the formula II:
—O—R
1
—O—D— (II)
wherein D has the meaning previously ascribed to it in formula I and R
1
is at least one divalent moiety selected from those of the formulae III, IV and V:
wherein X is a linear aliphatic group, branched aliphatic group, or cyclic aliphatic group. Linear and branched aliphatic groups are preferably those containing from 2 to about 20 carbon atoms, and include as illustrative non-limiting examples ethyl, propyl, isopropyl, butyl, tertiary-butyl, pentyl, neopentyl, hexyl, octyl, decyl, dodecyl. Cyclic aliphatic groups include cyclo- or bicycloalkyl radicals, preferably those containing from 3 to about 12 ring carbon atoms with a total number of carbon atoms less than or equal to 50. Some illustrative non-limiting examples of these cyclic aliphatic groups include cyclobutyl, cyclopentyl, cyclohexyl, methylcyclohexyl, and cycloheptyl. Aliphatic groups also include aralkyl radicals containing from 7 to about 14 carbon atoms; these include, but are not limited to, benzyl, phenylbutyl, phenylpropyl, and phenylethyl.
The polyester carbonates which find use in the instant invention are well known in the art as disclosed in, for example, U.S. Pat. Nos. 3,030,331; 3,169,121; 3,207,814; 4,238,596; 4,238,597; 4,487,896; 4,506,065, and in copending application Ser. No. 09/181,902, filed Oct. 29, 1998, and assigned to the same assignee as the instant application.
The first step of the melt condensation polymerization process is a pre-reaction of a carbonic acid diester, catalyst and diacid. The pre-reaction as used herein refers to an esterification process. The pre-reaction of the diacid and carbonic acid diester forms a carboxylic diester compound. The pre-reaction is allowed to proceed to substantially complete conversion of the diacid to a carboxylic diester compound. “Substantially complete conversion” as used herein refers to the reaction of the diacid and carbonic acid diester wherein at least 95% of the diacid and carbonic acid diester react to form a carboxylic diester compound.
Carbonic acid diesters are of the general formula, R
2
(CO
3
) wherein R is an alkyl or aryl group. Typical examples of carbonic acid diesters include, but are not limited to, diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, diethyl carbonate, dimethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate and mixtures thereof. The carbonic diester most typically used is diphenyl carbonate.
Diacids are of the general formula: R(COOH)
2
wherein R is an alkyl or aryl group. Examples of diacids include, but are not limited to, aliphatic diacids, aromatic diacids, and mixtures thereof. Examples of aliphatic diacids are adipic acid, sebacic acid, dodecanedioic acid, C-19 diacid, C-36 dimer diacid; and aromatic diacids such as isophthalic acid, terephthalic acid and 2,6-napthalenedicarboxylic acid.
The addition of the diacids to the melt condensation polymerization process effectively improves the melt viscosity of the polyester carbonate. Melt viscosity as used herein refers to the ability of a melted polyester carbonate to flow. Low melt viscosity enables rapid and efficient injection molding of the polyester carbonate.
Typical catalysts employed in the melt condensation polymerization process include, but are not limited to, alkali metal compounds, alkaline earth metal compounds, quaternary ammonium compounds and combinations thereof.
Useful alkali metal compounds as catalysts include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium hydrogencarbonate, potassium hydrogencarbonate, lithium hydrogencarbonate, sodium carbonate, potassium carbonate, lithium carbonate, sodium acetate, potassium acetate, lithium acetate, sodium stearate, potassium stearate, lithium stearate, sodium borohydride, lithium borohydride, sodium borophenolate, sodium benzoate, potassium benzoate, lithium benzoate, disodium hydrogenphosphate, dipotassium hydrogenphosphate, dilithium hydrogenphosphate, disodium, dipotassium and dilithium salts of biphenol A and sodium, potassium, and lithium salts of phenol.
Useful
Banach Timothy Edward
Davis Gary Charles
Lui Bill Kengliem
Bennett Bernadette M.
Boykin Terressa M.
General Electric Company
Johnson Noreen C.
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