Polyamide resin moldings
Provided is a xylylenesebacamide resin molding which is excellent in mechanical strength such as elastic modulus and avoids the problem of mechanical strength loss during long-term use. This is a molding of a polyamide resin or a polyamide resin composition containing the polyamide resin, wherein 70 mol % or more of the diamine structural unit is derived from xylylenediamine (A) and 50 mol % or more of the dicarboxylic acid structural unit is derived from sebacic acid (B), and the molding has a crystallinity index of 0 to 50% and a moisture content of 0.1 to 2% by mass.
1. A polyamide resin molding, comprising:
a polyamide resin comprising a diamine structural unit and a dicarboxylic acid structural unit or a polyamide resin composition including the polyamide resin,
wherein 70 mol % or more of the diamine structural unit is derived from xylylenediamine and 50 mol % or more of the dicarboxylic acid structural unit is derived from sebacic acid, the polyamide resin molding has a crystallinity index of 0 to 50% and a moisture content of 0.1 to 2% by mass, and the xylylenediamine is a mixture of m-xylylenediamine and p-xylylenediamine,
wherein the crystallinity index is determined by formula:
Crystallinity index (%)=( Qc/Qm )×100
where Qm is a heat of fusion of the polyamide resin molding, and Qc is a heat of crystallization of the polyamide resin molding during heating.
2. The polyamide resin molding according to claim 1 , wherein the polyamide resin has a number average molecular weight of 8,000 to 50,000.
3. The polyamide resin molding according to claim 1 , wherein the polyamide resin composition includes 0.1 to 2 parts by mass of a carbodiimide compound per 100 parts by mass of the polyamide resin.
4. The polyamide resin molding according to claim 1 , which is a film, sheet, thread, tube or injection-molded article.
5. The polyamide resin molding according to claim 1 , which is produced by a process comprising melting the polyamide resin or the polyamide resin composition in a cylinder under a condition satisfying a relation (1):
Tout≧Tin+ 20° C. (1),
where Tin is an inlet temperature of the cylinder, and Tout is an outlet temperature of the cylinder.
6. The polyamide resin molding according to claim 5 , wherein the polyamide resin or the polyamide resin composition are melted in the cylinder under a condition satisfying relations (2) and (3):
Tm+ 60° C.≧ Tout≧Tm+ 10° C. (2)
Tm+ 40° C.≧ Tin≧Tm− 50° C. (3),
where Tm is a melting point of the polyamide resin.
7. An injection-molded article, comprising:
the polyamide resin molding according to claim 1 .
8. The polyamide resin molding according to claim 1 , wherein the crystallinity index of the polyamide resin molding is 0 to 30%.
9. The polyamide resin molding according to claim 1 , wherein the crystallinity index of the polyamide resin molding is 0 to 15%.
10. The polyamide resin molding according to claim 1 , wherein the crystallinity index of the polyamide resin molding is 0 to 5%.