Compositions – Liquid crystal compositions
Reexamination Certificate
2001-12-11
2003-06-24
Huff, Mark F. (Department: 1756)
Compositions
Liquid crystal compositions
C264S021000
Reexamination Certificate
active
06582625
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for producing a thermotropic liquid crystalline polymer having a flow beginning temperature of 340° C. or more.
2. Description of the Related Art
Thermotropic liquid crystalline polymers are widely used as portable and thin electric and electronic parts materials due to excellent melt flowability and heat resistance.
Various methods are known for producing a thermotropic liquid crystalline resin.
For example, JP-A No. 2-69518 discloses a process for producing a whole aromatic polyester, and it is also disclosed that when a pre-polymer is polymerized in solid phase, it is necessary to select treating temperature and temperature raising speed so that particles of the resin are not sintered, and when sintered, polymerization is suppressed and removal of substances having low boiling point becomes insufficient.
Particularly, when producing a thermotropic liquid crystalline resin of high heat resistance having a flow beginning temperature of 340° C. or more by solid phase polymerization, it is difficult to effect solid phase polymerization so that particles of the resin are not sintered, and even when sintering of resin particles is few, blistering occurs on the surface of a molded article containing said resin under high temperature for soldering and the like.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a process for producing a thermotropic liquid crystalline resin having a flow beginning temperature of 340° C. or more which does not cause sintering of resin particles in solid phase polymerization, and scarcely causes a problem of blistering of a molded article containing said resin under high temperature environment.
The present inventors have intensively studied to find a process for producing a thermotropic liquid crystalline resin having a flow beginning temperature of 340° C. or more which has no problems as described above, and resultantly found that, a thermotropic liquid crystalline resin having a flow beginning temperature of 340° C. or more can be produced without causing problems as described above by controlling the average temperature raising speed of resin temperature (t) in a specific range when raising the resin temperature (t) from (FT
0
+20)° C. to (FT
0
+50)° C. and controlling the flow beginning temperature of a thermotropic liquid crystalline resin at each resin temperature in a specific range, and have completed the present invention.
Namely, the present invention relates to a process for producing a thermotropic liquid crystalline polymer having a flow beginning temperature of 340° C. or more comprising raising the temperature of a thermotropic liquid crystalline polymer from 200° C. or less to raising end temperature (A° C.) of (FT
0
+50)° C. or more in substantially solid phase condition,
wherein the thermotropic liquid crystalline polymer has a flow beginning temperature (FT
0
) of 200° C. or more and 300° C. or less, and in a step of raising the resin temperature (t) from (FT
0
+20)° C. to (FT
0
+50)° C. (step (1)), the average raising speed of the resin temperature is from over 0.1° C./min. to less than 0.5° C./min. and the flow beginning temperature of the thermotropic liquid crystalline polymer at each resin temperature is (t−10)° C. or more and (t+40)° C. or less.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Embodiments of the present invention are described below. In the following descriptions, “heat resistance” of a resin means a thermomechanical and chemical heat resistance. As measure of thermomechanical heat resistance, deflection temperature under load is exemplified. As measure of chemical heat resistance, soldering resistance is exemplified. “Processability” of a resin means melt flowability of a resin in injection molding mainly.
The thermotropic liquid crystalline resin of the present invention is, for example, a whole aromatic thermotropic liquid crystalline resin such as polyesters or polyesteramides having a whole aromatic skeleton, and there are exemplified
(1) resins having a structural unit derived from at least one aromatic hydroxycarboxylic acids,
(2) resins having a structural unit derived from aromatic dicarboxylic acid and aromatic diol,
(3) resins having a structural unit derived from aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid and aromatic diol,
(4) resins obtained by adding a structural unit derived from aromatic aminocarboxylic acid to (1),
(5) resins obtained by adding a structural unit derived from aminophenols to (2) and (3), and the like, and the thermotropic liquid crystalline resin usually forms an anisotropic melted body at temperatures of 400° C. or less.
Examples of the structural unit of the above-mentioned polyesters or polyesteramides having a whole aromatic skeleton include, but not limited to, the following units.
Structural units derived from aromatic hydroxycarboxylic acid:
Structural units derived from aromatic diol:
Structural units derived from aromatic dicarboxylic acid:
Structural units derived from aromatic aminocarboxylic acid:
Structural units derived from aminophenols:
The above-mentioned structural units derived from aromatic hydroxycarboxylic acid, aromatic diol, aromatic dicarboxylic acid, aromatic aminocarboxylic acid and aminophenols may have a substituent such as halogen atom, alkyl group, aryl group and the like on aromatic ring.
Among them, those having a total content of the above-mentioned structural units (I), (II), (III) and (IV) of 95 mol % or more are preferable from the standpoint of balance of heat resistance and processability, and those consisting essentially of the above-mentioned structural units (I), (II), (III) and (IV) are more preferable. Other structural units than (I), (II), (III) and (IV) can be appropriately selected from structural units derived from aromatic hydroxycarboxylic acid, aromatic diol, aromatic dicarboxylic acid, aromatic aminocarboxylic acid and aminophenols.
The molar ratio of (III)/(IV) is preferably from 8 to 50. When a thermotropic liquid crystalline resin having (III)/(IV) of less than 8 is used, it may be difficult to obtain a resin having a flow beginning temperature of 340° C. or more without causing fusion of a resin even if polymerization is effected according to the present invention. When (III)/(IV) is over 50, processability may be poor. From the standpoint of balance of sufficient heat resistance and processability, (III)/(IV) is more preferably from 18 to 40, and further preferably from 15 to 30.
The molar ratio of (I)/((I)+(II)+(III)+(IV)) is preferably from 0.4 to 0.7. When (I)/((I)+(II)+(III)+(IV)) is less than 0.4, the heat resistance of the thermotropic liquid crystalline resin may lower. When over 0.7, processability may be poor. From the standpoint of balance of sufficient heat resistance and processability, (I)/((I)+(II)+(III)+(IV)) is further preferably from 0.45 to 0.55.
The molar ratio of (II)/((III)+(IV)) is preferably from 0.9 to 1.1. When (II)/((III)+(IV)) is less than 0.9 or over 1.1, it may be difficult to obtain a resin having a flow beginning temperature of 340° C. or more without causing fusion of a resin even if polymerization is effected according to the present invention.
The objective of the present invention is to provide a thermotropic liquid crystalline resin having a flow beginning temperature of 340° C. or more. From the standpoint of processability of the resin, the flow beginning temperature is preferably 400° C. or less. When higher balance of heat resistance and processability is desired, the flow beginning temperature of the resin is more preferably from 370° C. to 390° C.
A process for producing a thermotropic liquid crystalline resin having a flow beginning temperature FT
0
of 200° C. or more and 300° C. or less before initiation of temperature raising (hereinafter, this resin is sometimes referred to as pre-polymer) used in the present invention is not particularly restri
Harada Hiroshi
Mizumoto Koichi
Nagashima Tohru
Birch & Stewart Kolasch & Birch, LLP
Huff Mark F.
Sadula Jennifer R.
Sumitomo Chemical Company Limited
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