Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2000-01-31
2001-07-10
Hampton-Hightower, P. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S170000, C528S322000, C524S401000, C524S405000, C524S412000, C524S432000, C524S469000, C524S600000, C524S606000
Reexamination Certificate
active
06258927
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a polyamide composition and moldings therefrom. The polyamide composition of the invention has good flame retardancy and heat resistance, and exhibits good thermal stability and continuous moldability when molded in melt, and it can be molded into good moldings having excellent appearances, especially fine color tone, without giving much gas. Therefore, the polyamide composition is favorable to applications that require flame retardation, for example, to components of electric and electronic appliances such as connectors, switches, relays, printed-wiring boards, etc.; reflecting mirrors such as lamp reflectors, etc.; various components of machines; various components of decorations; films, sheets, fibers, etc.
2. Description of the Background
As having excellent properties and good melt-moldability, polyamides such as nylon 6, nylon 66, nylon 46, semiaromatic polyamides and others are heretofore much used for components of electric and electronic appliances. However, those polyamides are easily combustible resins. Therefore, in the field that requires flame retardation, for example, for components of electric and electronic appliances and others, used are polyamide compositions containing a flame retardant and a flame-retardant synergist. As the flame retardant for that purpose, generally used are brominated polymers; and as the flame-retardation synergist, used are antimony oxide compounds.
For example, in Japanese Patent Laid-Open No. 260951/1988 (U.S. Pat. No. 5,115,010), it is written that a polyamide composition as prepared by adding a halogenopolystyrene and/or a polycondensate of a halogenophenol, and sodium antimonate to a semiaromatic polyamide has good flame retardancy, good heat resistance and good mechanical properties. In Japanese Patent Laid-Open No. 320503/1993, it is written that a polyamide composition as prepared by adding a polybromostyrene and sodium antimonate to a crystalline polyamide resin having a melting point of not lower than 270° C. has good heat resistance and gives good moldings having excellent surface appearances.
However, the present inventors have found that the polyamide compositions comprising a brominated polymer and sodium antimonate such as those described in the patent publications noted above could not exhibit good thermal stability and give much gas when they are molded in melt, and that their moldings have poor appearances in that they are unfavorably colored.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a polyamide composition having good flame retardancy and heat resistance, exhibiting good thermal stability and continuous moldability when molded in melt, and capable of being molded into good moldings having excellent appearances, especially fine color tone, without giving much gas (this means that the mold used for melt-molding the composition is hardly corroded), and
It is another object of the invention to provide moldings of the polyamide composition.
The inventors have worked to solve the problems noted above and to attain the objects as above, and, as a result, have found that, when an aromatic ring-containing bromine compound serving as a flame retardant and a specific, antimony-free compound serving as a flame-retardant synergist are added to a polyamide, then the resulting polyamide composition has good flame retardancy and heat resistance, and exhibits good thermal stability and continuous moldability when molded in melt, and it can be molded into good moldings having excellent appearances, especially fine color tone, without giving much gas.
Accordingly, the invention provides a polyamide composition comprising:
(A) 100 parts by weight of a polyamide,
(B) from 10 to 200 parts by weight of an aromatic ring-containing bromine compound, and
(C) from 0.1 to 100 parts by weight of at least one flame-retardant synergist selected from metal salts of stannic acid and alkaline earth metal salts of boric acid.
The present invention also relates to moldings of the polyamide composition, and to methods of making the moldings.
The present invention also relates to methods of making the inventive polyamide composition.
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description
DETAILED DESCRIPTION OF THE INVENTION
The polyamide (A) for use in the invention is not specifically limited and may be polyamide one generally usable in ordinary molding materials. It includes, for example, aliphatic polyamides such as nylon 6, nylon 11, nylon 12, nylon 66, nylon 610, nylon 612, nylon 69, nylon 1212, nylon 46 and their copolymers, etc.; as well as semiaromatic polyamides comprising dicarboxylic acid units of essentially aromatic dicarboxylic acid units and diamine units of essentially aliphatic alkylenediamine units, such as nylon 6T, nylon 9T, etc. Of those, preferred are semiaromatic polyamides as having good heat resistance and good water-absorption resistance.
As the aromatic dicarboxylic acid units constituting the semiaromatic polyamides, preferred are terephthalic acid units. Also preferably, the dicarboxylic acid units of the semiaromatic polyamides contain terephthalic acid units in an amount of from 60 to 100 mol %, more preferably from 70 to 100 mol %, even more preferably from 90 to 100 mol %. These ranges include all specific values and subranges therebetween, such as 65, 75, 80, 90, 95, 98 and 99 mol %. The preferred semiaromatic polyamides having a terephthalic acid unit content of at least 60 mol % give preferred moldings having better heat resistance and better water-absorption resistance.
Other dicarboxylic acid units than terephthalic acid units that may constitute the semiaromatic polyamides include, for example, units derived from aliphatic dicarboxylic acids such as malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, 2-methyladipic acid, trimethyladipic acid, pimelic acid, 2,2-dimethylglutaric acid, 3,3-diethylsuccinic acid, azelaic acid, sebacic acid, suberic acid, etc.; alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, etc.; and aromatic dicarboxylic acids such as isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,4-phenylenedioxy-diacetic acid, 1,3-phenylenedioxy-diacetic acid, diphenic acid, 4,4′-oxydibenzoic acid, diphenylmethane-4,4′-dicarboxylic acid, diphenylsulfone-4,4′-dicarboxylic acid, 4,4′-biphenyldicarboxylic acid, etc. The semiaromatic polyamides may contain one or more types of those additional units. Of the additional units, preferred are those derived from aromatic dicarboxylic acids. The additional dicarboxylic acid unit content of the semiaromatic polyamides is preferably at most 40 mol %, more preferably at most 30 mol %, even more preferably at most 10 mol %. These ranges include all specific values and subranges therebetween, such as at most 35, 25, 20 and 15 mol %. If desired, the semiaromatic polyamides may further contain units derived from polycarboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid and the like within a limited range within which the polyamide composition is moldable in melt.
As the aliphatic diamine units that constitute the semiaromatic polyamides, preferred are C
6-18
aliphatic alkylenediamine units. Also preferably, the diamine units of the semiaromatic polyamides contain C
6-18
aliphatic alkylenediamine units in an amount of from 60 to 100 mol %, more preferably from 75 to 100 mol %, even more preferably from 90 to 100 mol %. These ranges include all specific values and subranges therebetween, such as 65, 70, 80, 85, 95, 98 and 99 mol %. The preferred semiaromatic polyamides having a C
6-18
aliphatic alkylenediamine unit content of at least 60 mol % give preferred moldings having better heat resistance, better dimensio
Kuki Toru
Oka Hideaki
Tamura Kozo
Hampton-Hightower P.
Kuraray Co. Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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