Semiaromatic polyamides, processes for preparing the same and co

Details Semiaromatic polyamides, processes for preparing the same and co Semiaromatic polyamides, processes for preparing the same and co

1997-06-25

1998-12-15

Short, Patricia A.

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...

524409, 524411, 524607, 525 66, 525183, 525432, 528324, 5283291, 528338, 528339, 528491, C08G 6906, C08G 6926, C08G 6928, C08G 6930

Patent

active

058498265

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to semiaromatic polyamides capable of efficiently producing molded articles without bringing about contamination of a mold in the production of the molded articles and to processes for preparing the semiaromatic polyamides.
The present invention also relates to semiaromatic polyamide compositions containing the semiaromatic polyamides.


BACKGROUND ART

Various proposals relating to processes for preparing semiaromatic polyamides have been heretofore made. For example, Japanese Patent Laid-Open Publication No. 50230/1992 filed by the present applicant discloses a process for preparing a polyamide which comprises dicarboxylic acid units (a) composed of 50 to 90% by mol of terephthalic acid units and 0 to 40% by mol of units of other aromatic dicarboxylic acid than the terephthalic acid or units of a linear aliphatic dicarboxylic acid of 6 to 18 carbon atoms, and alkylenediamine units (b), and which has an intrinsic viscosity (.eta.), as measured in a concentrated sulfuric acid at 30.degree. C., of 0.5 to 3.0 dl/g.
In this connection, a composition comprising the above semiaromatic polyamide and a fibrous reinforcement is known to have high mechanical strength and heat resistance (see: Japanese Patent Laid-Open Publications No. 283654/1986, No. 249857/1989, No. 231965/1991 and No. 234764/1991).
A composition comprising the semiaromatic polyamide and a modified elastomeric polymer is known to have excellent heat resistance and impact resistance (see: Japanese Patent Laid-Open Publications No. 41318/1990, No. 108855/1992 and No. 98152/1993).
A composition comprising the semiaromatic polyamide and a flame retardant is known to be useful for connectors, etc. because of its excellent heat resistance and self-extinguishing properties (see: Japanese Patent Laid-Open Publications No. 260951/1988 and No. 138264/1990).
The polyamides mentioned above are prominently excellent in the heat resistance, mechanical properties and physiochemical properties, but when they are subjected to repeated injection molding operations using a mold, a white powder is sometimes precipitated inside the mold. As a result of analysis of the powder by the present inventors, the powder has been confirmed to be unreacted monomers and low oligomer components. When the polyamides are molded into electrical parts, particularly precision parts such as connectors, the unreacted monomers and low molecular weight oligomer components (referred to as "MO components" hereinafter) may have evil influence on the appearance of the molded articles or the dimensional accuracy thereof. Moreover, the MO components sometimes cause clogging of vent hole of the mold, and therefore the molding operation must be stopped to clean the mold.
Accordingly, there has been desired development of semiaromatic polyamides, which are excellent not only in mechanical strength such as rigidity, impact resistance and flexural strength but also in physiochemical properties such as flame retardance and heat resistance, which hardly bring about mold contamination in the molding process and clogging of vent hole of the mold, and which are capable of producing precision molded articles of good appearance.
It is, therefore, an object of the present invention to provide semiaromatic polyamides hardly bringing about mold contamination in the molding process and capable of producing molded articles of excellent properties and to provide processes for preparing the semiaromatic polyamides and compositions containing the semiaromatic polyamides.
It is another object of the invention to provide semiaromatic polyamide compositions having excellent heat resistance, mechanical strength and flame retardance and suitably used for producing precision parts such as connectors.


DISCLOSURE OF THE INVENTION

The semiaromatic polyamide of the present invention is a semiaromatic polyamide having (A) recurring units derived from terephthalic acid and an aliphatic diamine of 4 to 12 carbon atoms, and optionally, (B) recurring units derived from isophthali

REFERENCES:
patent: 4816557 (1989-03-01), Pipper et al.
patent: 4891420 (1990-01-01), Martin et al.
patent: 4978743 (1990-12-01), Selbeck et al.
patent: 5081222 (1992-01-01), Reimann et al.
patent: 5115010 (1992-05-01), Sakai et al.
patent: 5504146 (1996-04-01), Goetz et al.

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