Polyamide moulding compounds for producing optical lenses

• US 20040158028A1
• Filed: 04/12/2004
• Published: 08/12/2004
• Est. Priority Date: 05/08/2001
• Status: Active Grant

• Current Assignee: Ems-Chemie AG (Emesta Holding AG)
• Original Assignee: Ems-Chemie AG (Emesta Holding AG)
• Inventors: Bühler, Friedrich Severin
• Granted Patent: US 7,053,169 B2
• Time in Patent Office: Days
• US Class Current: 528/331
• CPC Class Codes: C08G 69/265 from at least two different diamines or at least two different dicarboxylic acids
• CPC Class Codes: C08G 69/36 derived from amino acids, polyamines and polycarboxylic acids
• CPC Class Codes: C08L 77/00 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 Class Codes: G02B 1/041 Lenses
• CPC Class Codes: Y10T 428/31504 Composite [nonstructural laminate]
• CPC Class Codes: Y10T 428/31725 Of polyamide

Abstract

The invention relates to new thermoplastically processible transparent polyamide molding materials based on copolyamides containing diamines and dicarboxylic acids with aromatic cores which exhibit a high index of refraction n_D²⁰ over 1.59 and a low density under 1.3 g/cm³. At the same time, a low birefringence, high hardness, and scratchresistance are achieved. The polyamide molding materials are fabricated by means of conventional pressure reactors (autoclaves) according to a modified technique. The granulate that is produced from the inventive molding materials is reshaped by thermoplastic processes like injection molding, particularly in multichamber cavity tools. The invention also relates to the utilization of the inventive molding materials for producing optical lenses.

Claims

1. Transparent thermoplastic polyamide molding materials based on copolyamides with a refractive index n_D²⁰ above 1.59, preferably above 1.6, with a primary proportion by weight of diamines and dicarboxylic acids with aromatic cores, characterized by the following chains, represented by Formula I:

—

{IPS—

NH—

R₁—

NH}_n1—

{TPS—

NH—

R₂—

NH}_n2—

{CO—

R₃—

NH}_n3—

 

 

(I)

where;

n₁=40 to 100 wt %

n₂=60 to 0 wt %

n₃=0 to 30 wt %, and where the proportions, in wt %, of n₁, n₂, and n₃ total 100%,

whereby the diamines with the cores R₁, R₂ can be identical or different, and at least 30 mol % diamines in relation to 100 mol % diamines consist of para-xylylene or meta-xylylene units and can consist of linear aliphatic or branched aliphatic chains with 2 to 12 (CH₂) units or chains with cycloaliphatic cores which can be incorporated individually or as blends, and whereby 100 mol % of the dicarboxylic acids consist of at least 40 mol % isophthalic acid (IPS) and, as a residue, terephthalic acid (TPS), which can be replaced partly or wholly by naphthalene dicarboxylic acids, whereby up to 30 wt % of the copolyamides of the molding compounds can be replaced by amino acids or lactams with core R₃, consisting of chains with 5 to 11 (CH₂) units.

2. Transparent thermoplastic polyamide molding materials with a refractive index n_D²⁰ above 1.59, preferably above 1.6, as claimed in claim 1, characterized in that the copolyamides have the composition according to Formula II:

MXDI/MXDT/6I/6T 

 

(II)

With the following mol % proportions of the respective components;

to 100 mol % meta-xylylenediamine (MXD)

80 to 0 mol % hexamethylenediamine (6)

50 to 100 mol % isophthalic acid (I) and

50 to 0 mol % terephthalic acid (T) in relation to 100 mol % diamine and 100 mol % dicarboxylic acids, whereby meta-xylylenediamine can be wholly or partly replaced by para-xylylenediamine, and terephthalic acid wholly or partly by naphthalenedicarboxylic acid, whereby symmetric isomers but preferably asymmetric isomers or blends thereof can be incorporated.

3. Transparent thermoplastic polyamide molding materials claimed in claim 1 with a refractive index n_D²⁰ above 1.59, preferably above 1.6, characterized in that the copolyamides have the composition according to Formula II:

MXDI/MXDT/6I/6T 

 

(II)

With the following mol % portions of the respective components;

to 80 mol % meta-xylylenediamine (MXD)

80 to 20 mol % hexamethylenediamine (6)

60 to 80 mol % isophthalic acid (I) and

40 to 20 mol % terephthalic acid (T) in relation to 100 mol % diamine and 100 mol % dicarboxylic acids.

4. Transparent thermoplastic polyamide molding materials claimed in claim 1 with a refractive index n_D²⁰ above 1.59, preferably above 1.6, characterized in that the copolyamides have the composition according to Formula III:

6I/6T/6NDC 

 

(III)

with the following proportions, in mol %, of the respective components;

to 80 mol % naphthalenedicarboxylic acid (NDC), with symmetric or asymmetric substitute positions or combinations thereof, particularly 2,6-naphthalenedicarboxylic acid,

40 to 20 mol % isophthalic acid (I),

40 to 0 mol % terephthalic acid (T) and

100 mol % hexamethylenediamine (6), which can be wholly or partly replaced by ethylenediamine, trimethylhexamethylenediamine, or linear diamines with 8 to 12 CH₂ groups or cycloaliphatic diamines such as norbomanediamine, 4,4-diaminodicyclohexylmethane, 3,3-dimethyl-4,4-diaminodicyclohexylmethane or blends thereof, in relation to 100 mol % diamine and 100 mol % dicarboxylic acids.

5. Polyamide molding materials according to one of the claims 1 to 4, characterized in that the copolyamides contain at least 50 mol % diamines with aromatic cores such as meta-xylylenediamine, para-xylylenediamine in relation to 100 mol % diamine.

6. Polyamide molding materials claimed in one of the claims 1 to 5, characterized in that up to 5 mol % of the diamines and/or the dicarboxylic acids with aromatic cores can be replaced by branched or unbranched aliphatic diamines with 2 to 12 (CH₂) units or aliphatic dicarboxylic acids with 2 to 12 CH₂ units, which can be branched or unbranched.

7. Polyamide molding materials claimed in claim 6, characterized in that contained in the chains of the copolyamides, there are up to 5 mol % cycloaliphatic diamines or cycloaliphatic dicarboxylic acids with skeletons such as norbornyi, cyclohexyl, or dicyclohexyl methane, dicyclohexylpropane, di(methylcyclohexyl)methane, di(methylcyclohexyl)propane.

8. Polyamide molding materials claimed in one of the claims 1 to 7, characterized in that, in order to accelerate the reaction, phosphorous catalysts such as H₃PO₂, H₃PO₃, H₃PO₄ are added to the aqueous mixture during the polycondensation in amounts equaling 0.01 to 0.2 wt %.

9. Polyamide molding materials claimed in one of the claims 1 to 8, characterized in that phosphorous stabilizers of the type R₃PO₂, R₃PO₃, R₃PO₄ with R═

H, or metal ions or organic linear or cyclic residues or sterically hindered phenols, are incorporated in amounts equaling 0.01 to 0.2 wt % for stabilizing the color in the course of polymerization and later processing.

10. Polyamide molding materials claimed in one of the claims 1 to 9, characterized in that, in order to control the chain length, either monofunctional amines or monofunctional acids are polymerized in, or an excess of diamine or dicarboxylic acid is used, whereby controller types with stabilizer functions are preferred, for instance multi-substituted piperidyl groups and tertiary butyl phenyl groups.

11. Polyamide molding materials claimed in claim 10, characterized in that aliphatic or cycloaliphatic amines, particularly hexylamine and/or cyclohexylamine, are used as monofunctional amines, and aliphatic, cycloaliphatic, or aromatic acids, particularly acids from the benzoic, acetic, and propionic groups, are used as monofunctional acids.

12. Polyamide molding materials claimed in any of the preceding claims 1 to 11, characterized in that the copolyamides have a relative viscosity (r.V.) of from 1.33 to 1.65, measured 0.5% in m-cresol.

13. Method for producing molded bodies from the molding materials claimed in one or more of the claims 1 to 12, characterized in that the known methods for thermoplastics, such as injection molding, preferably in multi-cavity tools, are applied for remolding the granulate that is produced from the molding compounds into optical lenses or lens blanks.

14. Method for processing the polyamide molding materials claimed in claim 13, characterized in that films or other molded parts—

with polarization characteristics or with UV absorbers that filter out UV light under 400 nm, or dyes for tinting the lenses, or additives that alter their appearance based on temperature effects, or thermochromatic additives that alter the tint depending on the temperature or depending on the wavelength of the incoming light—

are back-injected.

15. Method for processing the polyamide molding materials claimed in claim 14, characterized in that the back-injection of protective films achieves an improved chemical resistance, an improved load capacity, an improved anti-friction or abrasion behavior at the molded part.

16. Method for processing the molded bodies that are produced from the molding materials claimed in one of the claims 13 to 15, comprising the varnishing of the surfaces with hardcoat, softcoat, or UV protection varnish, evaporation coating with carbon or metal atoms, plasma treatment, and layer polymerization.

17. Optical lenses for eyeglasses, characterized in that they are produced with the inventive molding materials claimed in one of the claims 1 to 12 and the method claimed in one of the claims 13 to 15.

18. Optical lenses for cameras, binoculars, microscopes, electro-optical measuring and testing devices, optical filters, headlight lenses, lamp lenses, projectors and video projectors, viewing windows, and gage glasses, characterized in that they are produced with the inventive molding materials claimed in one of the claims 1 to 12 and the method claimed in one of the claims 13 to 15.

19. Utilizing the inventive molding materials claimed in one of the claims 1 to 12 for producing blends or alloys, characterized in that amorphous or semi-crystalline polyamides are used as blend or alloy components, these being furnished with the usual additives such as strengtheners, nanoparticles, impact strength modifiers, dyes, flame retardants, softeners, stabilizers, and lubricants.