Process for preparing injection molded parts with decreased glass fiber read out

Patent metadata

Field	Value
Publication number	US-9399314-B2
Application number	US-201013203522-A
Country	US
Kind code	B2
Filing date	Feb 8, 2010
Priority date	Mar 4, 2009
Publication date	Jul 26, 2016
Grant date	Jul 26, 2016

Abstract

The present invention relates to a process for preparing an injection molded part, comprising the following steps: a preparing a glass fiber reinforced polyamide-6 composition with a relative viscosity of less than 2.4; b heating a such composition to obtain a viscous liquid; c filling a mold cavity with the viscous liquid with a filling time of at least 0.8 s; d leaving the viscous liquid in the mold under pressure until it cools to form a part; e opening the mold; f ejecting the part; wherein the polyamide-6 composition has a crystallization temperature under hyper DSC conditions of less than 168° C. The invention also relates to an injection molded part a having a maximum wall thickness of at least 2.5 mm; and/or b a part weight of at least 100 g per injection point; wherein the part consists of a glass fiber reinforced semi-crystalline polyamide-6 composition having a relative solution viscosity of less than 2.4, wherein the polyamide-6 composition has a crystallization temperature under hyper DSC conditions of less than 168° C.

First claim

The invention claimed is:

1. A process for preparing an injection molded part, comprising the following steps:
(a) providing a glass fiber reinforced semi-crystalline polyamide-6 composition comprised of a melt-blend of (i) glass reinforcement fibers, (ii) a base polyamide-6, and (iii) an amount of a low molecular weight polyamide oligomer sufficient to impart to the polyamide-6 composition a relative solution viscosity of less than 2.4 and a crystallization temperature under hyper DSC conditions of less than 168° C.;
(b) heating the polyamide-6 composition to obtain a viscous liquid thereof;
(c) filling a mold cavity with the viscous liquid to achieve a filled mold cavity with a filling time of at least 0.8 seconds;
(d) leaving the viscous liquid in the mold cavity under pressure until the viscous liquid cools to form an injection molded part;
(e) opening the mold; and
(f) ejecting the injection molded part.

2. The process according to claim 1 , wherein the injection molded part has a maximum wall thickness of at least 2.5 mm.

3. The process according to claim 1 , wherein the polyamide-6 composition has a relative solution viscosity of less than 2.3.

4. The process according to claim 1 , wherein the polyamide-6 composition has a relative solution viscosity of less than 2.2.

5. The process according to claim 1 , wherein the polyamide-6 composition is a melt-blend of 80-99.5 wt % of the base polyamide-6 and 0.5-20 wt % of the low-molecular weight polyamide oligomer, wherein the total amount of the base polyamide-6 and the low-molecular weight polyamide oligomer is 100%.

6. The process according to claim 5 , wherein the base polyamide-6 has a weight-average molecular weight of at least 10,000 g/mol and the low-molecular weight polyamide oligomer has a weight-average molecular weight of at most 5,000 g/mol.

7. The process according to claim 1 , wherein the glass reinforcement fibers are present in the polyamide-6 composition in an amount of at least 10 wt %, based on the total weight of the polyamide-6 composition.

8. The process according to claim 1 , wherein the glass reinforcement fibers are present in the polyamide-6 composition in an amount of at most 60 wt %, based on the total weight of the polyamide-6 composition.

9. The process according to claim 1 , wherein the polyamide-6 composition further comprises a black polyaniline derivative.

10. The process according to claim 9 , wherein the black polyaniline derivative is nigrosine.

11. The process according to claim 1 , wherein the injection molded part has a maximum wall thickness of at least 3.0 mm.

12. The process according to claim 1 , wherein the injection molded part has a maximum wall thickness of at least 3.5 mm.

13. The process according to claim 1 , wherein the injection molded part has a maximum wall thickness of at least 4.0 mm.

14. The process according to claim 1 , wherein the glass reinforcement fibers are present in the polyamide-6 composition in an amount of at least 20 wt %, based on the total weight of the polyamide-6 composition.

15. The process according to claim 1 , wherein the glass reinforcement fibers are present in the polyamide-6 composition in an amount of at least 30 wt %, based on the total weight of the polyamide-6 composition.

16. The process according to claim 6 , wherein the low molecular weight polyamide oligomer is a polyamide-66 (PA66) oligomer.

17. An injection molded part obtained by the process according to claim 1 , wherein injection molded part has a weight which is at least 100 g per injection point.

18. An injection molded part having (a) a maximum wall thickness of at least 2.5 mm; and/or (b) a part weight of at least 100 g per injection point; wherein the injection molded part is formed of a glass fiber reinforced semi-crystalline polyamide-6 composition comprised of a melt-blend of (i) glass reinforcement fibers, (ii) a base polyamide-6, and (iii) an amount of a low molecular weight polyamide oligomer sufficient to impart to the polyamide-6 composition a relative solution viscosity of less than 2.4 and a crystallization temperature under hyper DSC conditions of less than 168° C.

Assignees

• Van Der Vegte Eric Willem
• Hoekstra Johannes
• Rulkens Rudy
• Dsm Ip Assets Bv

Inventors

• Van Der Vegte Eric Willem
• Hoekstra Johannes
• Rulkens Rudy

Classifications

• C08L77/00 Primary

  Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain (of polyhydrazides C08L79/06; of polyamideimides or polyamide acids C08L79/08); Compositions of derivatives of such polymers · CPC title

• B29K2077/00

  Use of {PA, i.e.} polyamides, e.g. polyesteramides {or derivatives thereof}, as moulding material · CPC title

• B29C45/00

  Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor (injection blow-moulding B29C49/06) · CPC title

• C08L2205/02

  containing two or more polymers of the same C08L -group · CPC title

• B29C45/0005 Primary

  using fibre reinforcements · CPC title