Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2000-05-26
2001-04-24
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
C528S198000
Reexamination Certificate
active
06222004
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a branched polycarbonate resin, precisely to a branched polycarbonate resin that exhibits improved moldability in blow molding and so on and gives good moldings especially having improved appearances and color tone.
BACKGROUND OF THE INVENTION
Generally having good transparency, good heat resistance and good mechanical properties, polycarbonate resins to be produced from bisphenol A and others have many applications in various fields. However, the polycarbonate resins generally have low melt tension. Therefore, when molded through blow molding, extrusion, vacuum forming and so on, they are often defective in that their moldings could not all the time have even thickness. In addition, as they often draw down while being molded, they could not be formed into satisfactory moldings.
For overcoming the defects, Japanese Patent Laid-Open No. 47228/1984 discloses a method of adding from 0.1 to 2.0 mol % or so of a branching agent having three functional groups to a polymerization system to give a branched polycarbonate resin.
The melt tension of the branched polycarbonate resin as produced according to that method could surely be increased in some degree, but is not still on a satisfactory level. On the other hand, in order to produce a branched polycarbonate resin having a satisfactory level of melt tension according to the method, a large amount of the branching agent must be used. In that case, however, increasing the amount of the branching agent added will lead to an unfavorable situation where crosslinked polycarbonate resins are readily produced. This is problematic in that the resins are often gelled. In addition, it is said that, with the increase in the branching agent added, the impact resistance of the polycarbonates produced is to lower. For these reasons, the acceptable amount of the branching agent is limited, and it is desired to reduce as much as possible the amount of the branching agent to be added.
The object of the present invention is to provide a branched polycarbonate resin of which the branching agent content is controlled low, which has good melt characteristics including high melt tension, and has good heat stability, and which therefore can be stably produced and molded even through blow molding, extrusion, vacuum forming and so on without being yellowed during the residence time in the molding process.
We, the present inventors have already invented a branched polycarbonate resin having good melt characteristics including high melt tension, for which is used a tetrahydric phenol having a specific structure and serving as a branching agent with the amount of the branching agent to be used being controlled low (Japanese Patent Application No. 228742/1997).
DISCLOSURE OF THE INVENTION
We, the present inventors have assiduously studied so as to obtain a polycarbonate having better heat stability, and, as a result, have found that, when a tetrahydric phenol having a specific structure is used as the branching agent in producing the polymer, then the above-mentioned object can be attained. On the basis of this finding, we have completed the present invention
Specifically, the invention provides a branched polycarbonate resin for which is used a tetrahydric phenol having a structure of the following general formula (1) and serving as a branching agent, and which has a branching agent content (that is, the ratio of the branching agent in terms of mol % to the total by mol of (dihydric phenol+chain terminator+branching agent)) of from 0.01 to 0.4 mol % and an intrinsic viscosity [&lgr;] of from 0.5 to 0.6, and is substantially free from crosslinks:
wherein A, R
1
, R
2
and p are as follows:
A represents a polymethylene group having from 7 to 20 carbon atoms, an alkylene or alkylidene group having from 2 to 20 carbon atoms but excluding polymethylene groups having from 1 to 6 carbon atoms, a cycloalkylene or cycloalkylidene group having from 5 to 20 carbon atoms, an arylene or alkylarylene group having from 6 to 20 carbon atoms, an arylalkylene group having from 6 to 20 carbon atoms, —O—, —CO—, —S—, —SO—, or —SO
2
—;
R
1
represents a hydrogen atom, an alkyl group having from 1 to 8 carbon atoms, an aryl group having from 6 to 20 carbon atoms, or an arylalkyl group having from 7 to 20 carbon atoms, and R
1
's may be the same or different;
R
2
represents a halogen atom, an alkyl group having from 1 to 8 carbon atoms, an aryl group having from 6 to 20 carbon atoms, or an arylalkyl group having from 7 to 20 carbon atoms, and plural R
2
's, if any, may be the same or different;
p indicates an integer of from 0 to 4; or they are as follows:
A represents a single bond, a polymethylene group having from 1 to 20 carbon atoms, an alkylene or alkylidene group having from 2 to 20 carbon atoms, a cycloalkylene or cycloalkylidene group having from 5 to 20 carbon atoms, an arylene or alkylarylene group having from 6 to 20 carbon atoms, an arylalkylene group having from 6 to 20 carbon atoms, —O—, —CO—, —S—, —SO—, or —SO
2
—;
R
1
represents an alkyl group having from 7 to 20 carbon atoms, an aryl or alkylaryl group having from 6 to 20 carbon atoms, or an arylalkyl group having from 7 to 20 carbon atoms, and R
1
's may be the same or different;
R
2
represents a halogen atom, an alkyl group having from 1 to 8 carbon atoms, an aryl group having from 6 to 20 carbon atoms, or an arylalkyl group having from 7 to 20 carbon atoms, and plural R
2
's, if any, may be the same or different;
p indicates an integer of from 0 to 4.
The invention also provides a branched polycarbonate resin for which is used a tetrahydric phenol having a structure of the following general formula (2) and serving as a branching agent, and which has a branching agent content (that is, the ratio of the branching agent in terms of mol % to the total by mol of (dihydric phenol+chain terminator+branching agent)) of from 0.01 to 0.4 mol % and an intrinsic viscosity [&lgr;] of from 0.5 to 0.6, and is substantially free from crosslinks:
wherein A
1
, R
3
, R
4
and p are as follows:
A
1
represents an arylene or alkylarylene group having atom 6 to 20 carbon atoms, or an arylalkylene group having from 6 to 20 carbon atoms,
R
3
represents a hydrogen atom, an alkyl group having from 1 to 8 carbon atoms, an aryl group having from 6 to 20 carbon atoms, or an arylalkyl group having from 7 to 20 carbon atoms, and R
3
's may be the same or different;
R
4
represents a halogen atom, an alkyl group having from 1 to 8 carbon atoms, an aryl group having from 6 to 20 carbon atoms, or an arylalkyl group having from 7 to 20 carbon atoms, and plural R
4
's, if any, may be the same or different;
p indicates an integer of from 0 to 4.
BEST MODES OF CARRYING OUT THE INVENTION
The invention is described in detail hereinunder.
1. Branched polycarbonate resin:
The branched polycarbonate resin of the invention is characterized by the following characteristics:
(1) Characteristics:
<1> Branching agent content:
The branching agent content of the resin indicates the mol % of the branching agent in the resin, relative to the number of all mols of (dihydric phenol+chain terminator+branching agent) therein, and falls between 0.01 and 0.4 mol %, but preferably between 0.05 and 0.40 mol %. If the content is smaller than 0.01 mol %, the melt tension of the resin will be low, and blow molding of the resin will be difficult. If, on the other hand, the content is larger than 0.4 mol %, the resin will be crosslinked and gelled whereby the impact resistance of the moldings of the resin will be low.
<2> Intrinsic viscosity [&lgr;]:
The intrinsic viscosity of the resin preferably falls between0.5and 0.6. If it is smaller than 0.5, the melt tension of the resin will be low, and blow molding of the resin will be difficult; but if larger than 0.6, the fluidity of the resin will be poor, and the moldability thereof and even the appearances of the resin moldings will be poor.
<3> The branched polycarbon
Ishikawa Yasuhiro
Okamoto Masaya
Boykin Terressa M.
Idemitsu Petrochemical Co., LTD
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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