Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2002-01-09
2004-03-16
Buttner, David J. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S483000, C525S146000
Reexamination Certificate
active
06706797
ABSTRACT:
The present invention provides polycarbonate moulding compositions with good release properties having methyl-branched alkanes or alkane mixtures as release agents, optionally in addition to other conventional polycarbonate additives.
There are numerous patents and publications describing the releasing action of additives in thermoplastics in general and in polycarbonate in particular. The substances most commonly used as release agents are the esters of long-chain aliphatic acids and alcohols. The use of esters of fatty acid alcohols or polyols, such as e.g. pentaerythritol with fatty acids, such as are described in DE 33 12 158, EP 100 918, EP 103 107, EP 561 629, EP 352 458, EP 436 117, or, using guerbet alcohols, U.S. Pat. No. 5,001,180, DE 33 12 157, U.S. Pat. No. 5,744,626, is mentioned here by way of example. All of these esters have the disadvantage that they have a tendency towards interesterification with the polycarbonate due to impurities having a catalytic effect and to the processing temperature. This becomes particularly apparent at the high melt temperatures necessary for short cycle times.
Other release agents that do not have this disadvantage, such as long-chain ketones, tend to form chromophores due to self-condensation and are poorly accessible (EP 100 918).
Siloxanes, which are likewise used (U.S. Pat. No. 4,536,590, U.S. Pat. No. 4,390,651, U.S. Pat. No. 3,751,519), possess an adequate temperature resistance but are very poorly compatible with polycarbonate and in the concentrations required to be effective they lead to haze.
&agr;-olefin polymers (EP 561 630, EP 230 015) with residual double bonds (DE 32 44 499) are not colourfast and in the case of hydrogenated systems, as with the long-chain alkanes (U.S. Pat. No. 4,415,696), there is a compatibility problem with polycarbonate, and the wax-like, often partially liquid partially waxy consistency of these products is restricting.
Warp-free demoulding of polycarbonate mouldings with no deterioration in the very high-grade surface represents an ever greater challenge due to the demands for shorter cycle times and higher processing temperatures at a time when shapes are becoming ever more complex. Many problems can commonly be overcome only with a tailor-made release agent formulation. There is therefore a continual need for new potential release agents. The object was therefore to find release agents that do not tend towards interesterification with the polycarbonate nor form deposits on the mould and that do not lead to haze or discoloration in the effective concentrations.
The object was therefore to develop a readily releasing moulding composition which in addition to outstanding mould release properties and transparency also has satisfactory temperature resistance without discoloration or interesterification.
The object was achieved by the use of methyl-branched alkanes which have an adequate solubility and stability in polycarbonate.
The present invention provides polycarbonate moulding compositions containing hydrocarbons having 15 to 600 carbon atoms, whereby these hydrocarbons are contained in quantities of 0.005 to 5.0 wt. % relative to the weight of the entire moulding composition, and these hydrocarbons consist of methyl-branched alkane chains, whereby they display a proportion by weight of branches of between 5 wt. % and 30 wt. % relative to the carbons in the chain.
The preferred content of hydrocarbons is 0.01 to 2.0 wt. %, most particularly preferably 0.02 to 1.0 wt. %.
Hydrocarbons having 15 to 100 carbon atoms are likewise preferred, with those having 15 to 40 carbon atoms being particularly preferred.
The hydrocarbons according to the invention particularly preferably consist of alkanes, of which the carbons in the branching methyl groups have a proportion by weight relative to the carbons in the chain of between 10 wt. % and 30 wt. %; particularly preferred are those constituted from isoprene units, in this case before hydrogenation, particularly preferably from over 90% hydrogenated isoprene units, most particularly preferably from over 95% hydrogenated isoprene units, optionally using comonomers, particularly 2,3-dimethyl butadiene, butadiene, propene and/or isobutene, in the range from 0 to 50 mol % (relative to the isoprene units), but particularly those that are formally constituted from isoprene units before saturation of the double bonds, whereby those containing 15, 20, 25, 30, 35 or 40 C atoms or mixtures thereof are preferred, squalane (30 C atoms) being most particularly preferred.
The polycarbonate moulding compositions can optionally be supplemented with other additives conventionally used in polycarbonate, such as e.g. heat stabilisers, UV/IR stabilisers, other release agents, flame ratardants, antidripping agents, lubricants, flow promoters, fillers, colorants such as pigments or colour concentrates, glass fibres, fillers and blend components such as ABS, SAN, EPDM or polyesters based on terephthalic acid and diols.
The moulding compositions according to the invention can be contaminated with impurities contained in the individual components of the moulding composition due to their synthesis, working up, processing and storage, together with contamination originating during production or processing of the moulding compositions according to the invention. The aim is to work with products that are as clean as possible, however.
Alkanes according to the invention are those of natural or synthetic origin having lateral methyl groups and a total of 15 to 600 carbon atoms, preferably 15 to 100 carbon atoms, whereby the patent also provides mixtures of these hydrocarbons. Hydrocarbons are preferred which are constituted formally or by actual synthesis of 50 to 100 mol % of isoprene units, i.e. which contain this C
5
unit after saturation of the double bonds remaining after polymerisation, with the proviso that the carbons in the branching methyl groups have a proportion by weight, relative to the carbons in the chain, of between 10 wt. % and 30 wt. %, preferably between 10 wt. % and 30 wt. %. Comonomers such as can be used in addition to isoprene are those such as are conventionally used in rubber production and polyolefin chemistry, particularly 2,3-dimethyl butadiene, butadiene, propene and/or isobutene. Such saturated aliphatics that arise purely mathematically from isoprene via “head-head” or “head-tail” linkage before saturation of the remaining double bonds are particularly preferred, whereby both linkage types can also occur side by side, particularly squalane.
Mixtures of the hydrocarbons according to the invention can also be used, optionally with admixtures of other alkanes, including linear types, of between 0 and 30 wt. % relative to the amount of alkanes according to the invention.
The alkanes used should have the lowest possible residues of double bonds; iodine values of below 10, ideally below 5, are desirable.
The alkanes according to the invention are commercial and can be acquired in the chemicals trade.
Thermoplastic, aromatic polycarbonates in the sense of the present invention are both homopolycarbonates and copolycarbonates; the polycarbonates can be linear or branched by known means.
Part, up to 80 mol %, preferably from 20 mol % to 50 mol %, of the carbonate groups in the polycarbonates that are suitable according to the invention can be replaced by aromatic dicarboxylic acid ester groups. Such polycarbonates, which contain both acid radicals of the carbonic acid and acid radicals of aromatic dicarboxylic acids incorporated into the molecular chain, are, strictly speaking, aromatic polyester carbonates. For the sake of simplicity they are subsumed under the generic term of thermoplastic, aromatic polycarbonates in the present application.
The polycarbonates for use according to the invention are produced by known means from diphenols, carbonic acid derivatives, optionally chain terminators and optionally branching agents, whereby a part of the carbonic acid derivatives is replaced by aromatic dicarboxylic acids or derivatives of dicarboxylic acids in or
Döbler Martin
Ebert Wolfgang
Fischer Peter
Genz Joachim
Haese Wilfried
Bayer Aktiengesellschaft
Buttner David J.
Gil Joseph C.
Matz Gary F.
Preis Aron
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