Transparent polyamide molding compositions

Abstract

A polyamide molding composition is described, comprising at least one transparent homopolyamide and/or copolyamide in a proportion by weight of from 70 to 99% by weight; at least one further polymer in a proportion by weight of from 1 to 30% by weight; and also optionally further dyes and/or additives. The polyamide molding composition is one wherein the further polymer is a polyesteramide, and wherein the light transmittance to ASTM D1003 of a sheet of thickness 2 mm produced from the polyamide molding composition is at least 88%, and preferably wherein the notched impact resistance of an article produced therefrom is at least 14 kJ/m2.

Description

EXAMPLES E1 TO E5 AND COMPARATIVE EXAMPLES CE1 TO CE5

First, the polymer mixtures composed of transparent polyamide and of a block copolymer were prepared in a Collin Teach-Line ZK25T L/D=18 twin-screw extruder. The barrel temperatures, except in the feed zone, were from 220 to 280° C., and the screw rotation rate was from 120 to 250 rpm.

These mixtures were then processed in an Arburg Allrounder 350-90-220D injection-molding machine to give round plaques of size 70×2 mm (optical tests) and the other test specimens needed, barrel temperature being from 220 to 280° C. and mold temperature being from 20 to 60° C. The screw rotation rate was from 150 to 400 rpm.

The compositions and the properties of the polyamide molding compositions used in each of the inventive examples and those of the comparative examples, are collated in Table 1.

The molding compositions prepared were tested as follows:

MVR: (melt volume rate) at 275° C. to ISO 1133

IR: impact resistance to ISO 179/1eU (Charpy)

NIR: notched impact resistance to ISO 179/1eA (Charpy)

Tensile modulus of elasticity, ultimate tensile strength, and tensile strain at break were determined to ISO 527 on ISO tensile specimens, ISO/CD 3167 standard, type A1, 170×20/10×4 mm at a temperature of 23° C. The mechanical properties were determined in the dry state.

Relative viscosity (η_rel) was determined at 20° C. on a 0.5% strength m-cresol solution to the DIN EN ISO 307 standard.

Transmittance, haze, and clarity were determined at 23° C. using a haze-gard plus from Byk Gardner to ASTM D1003 (CIE C illuminant) on round plaques of size 70×2 mm. Transmittance, clarity, and haze are stated in % of the amount of incident light.

Yellowness index was measured to ASTM D1925 (C2 illuminant) on round plaques of size 70×2 mm.

FE7314 and FE7334 are polyesteramides based on nylon-12 and dimerdiol, these being generally described in EP 0 955 326 B1 (T_g=−30° C.)

PEBAX 5533 is a nylon-12 block copolymer having ether segments from ARKEMA, France. (T_g=about −40°).

Lotader GMA AX8840 is a polyethylene copolymer having 8% by weight of glycidyl methacrylate from Arkema (FR).

Paraloid BTA 753 is a core-shell impact modifier based on methacrylates, butadiene, and styrene from Rohm & Haas (DE).

MB XE 3680 is a commercial masterbatch based on a low-viscosity nylon-12 with UV stabilizers and heat stabilizers from EMS-Chemie AG, Switzerland.

	TABLE 1
	Example
	E1	E2	E3	E4	E5	CE1	CE2	CE3	CE4	CE5
Compositions
TR 90	% by wt.	90	90	85	87		100	90	90	84	90
FE5537	% by wt.					87
FE7334	% by wt.	10		15
FE7314	% by wt.		10		10	10				10
Lotader GMA	% by wt.							10		3
AZ8840
Paraloid BTA 753	% by wt.								10
Pebax 5533	% by wt.										10
MB PA12 XE	% by wt.				3	3				3
3680
Base data
Water	%	0.010	0.014	0.013	0.013	0.015	0.013	0.014	0.015	0.016	0.011
Tg	° C.	152	153	152	152	152	153	153	151	153	149
MVR 275° C./	ml/10 min	25	25	38	24	26	16	13	15	26	25
5 kg
Optical properties
Yellowness index	—	2.4	1.6	2.9	1.3	1.3	−0.3	7.3	9.0	5.0	9.5
ASTM D1925
(C2 illuminant)
Haze ASTM	%	1.9	2.6	3.5	2.2	5.0	1.1	16.6	82.5	64.8	6.0
D1003
Transmittance	%	93.1	93.6	92.5	93.4	91.9	93.7	86.9	72.6	81.7	88.8
ASTM D1003
Clarity	%	99.5	97.9	97.5	98.3	97.8	99.5	99.1	94.8	95.1	99.5
Mechanical properties
Tensile modulus	MPa	1330	1330	1250	1330	1310	1500	1270	1280	1250	1400
Ultimate tensile	MPa	51	52	47	52	50	82	48	48	51	47
strength
Tensile strain at	%	130	130	130	140	140	150	115	125	145	105
break
Impact resistance	kJ/m2	nf	nf	nf	nf	nf	nf	nf	nf	nf	nf
23° C.,
Charpy new
Notched impact	kJ/m2	15.8	17.2	19.5	14.7	17.4	8.2	63.0	37.5	24.4	13.8
resistance
23° C.,
Charpy new

EXAMPLES E6 TO E10

Additional supportive examples 6-10 were manufactured and tested, this time with the additional additive nylon-12, used in the form of GRILAMID L16 in a proportion of from 5 to 10% by weight.

The corresponding results are collated in Table 2, and it appears that addition of from 5 to 10% by weight of this additive can additionally substantially improve mechanical properties, while optical properties in essence remain identical or indeed in some cases are even improved.

	TABLE 2
	Example
	E6	E7	E8	E9	E10
Compositions
GRILAMID TR 90	% by wt.	80	80	80	80
(ηrel = 1.75)
GRILAMID TR 90	% by wt.					80
(ηrel = 1.65)
FE7314 (ηrel = 1.35)	% by wt.	10	15
FE7314 (ηrel = 1.58)	% by wt.				10	10
FE7311 (ηrel = 1.62)	% by wt.			10
GRILAMID L16	% by wt.	10	5	10	10	10
(ηrel = 1.66)
Base data
Water	%	0.012	0.013	0.012	0.014	0.011
Tg	° C.	131	137	128	131	130
MVR 275° C./5 kg	ml/10 min	31	40	44	40	63
Optical properties
Sprue marking	—	no	no	no	no	no
Yellowness index	—	3.9	5.0	2.3	3.5	3.2
ASTM D1925
(C2 illuminant)
Haze ASTM D1003	%	2.1	3.9	0.7	3.6	1.8
Transmittance	%	92.7	92.3	93.3	92.9	93.1
ASTM D1003
Clarity	%	99.2	94.4	99.5	96.5	98.4
Mechanical properties
Tensile modulus	MPa	1430	1360	1450	1420	1410
Ultimate tensile	MPa	52	55	59	56	54
strength
Tensile strain at	%	140	150	180	160	160
break
Impact resistance	kJ/m2	nf	nf	nf	nf	nf
23° C., Charpy new
Notched impact	kJ/m2	15.5	16.2	14.7	14.4	14.0
resistance 23° C.,
Charpy new

FE7311: polyesteramides based on nylon-12 and dimerdiol; FE 7314 also contains polyester segments based on dimer acid and dimerdiol.

GRILAMID L16 is a low-viscosity nylon-12 whose solution viscosity measured in m-cresol (0.5% by weight) is 1.66.

Claims

1. A polyamide molding composition comprising at least one transparent homopolyamide and/or copolyamide in a proportion by weight of from 70 to 99% by weight;at least one further polymer in a proportion by weight of from 1 to 30% by weight;and also optionallyfurther dyes and/or additives,whereinthe further polymer is a polyesteramide, andwhereinthe light transmittance of a sheet of thickness 2 mm produced from the polyamide molding composition is at least 88%.

2. The polyamide molding composition as claimed in claim 1, wherein the light transmittance of the sheet is at least 90%, preferably at least 91%.

3. The polyamide molding composition as claimed in any of the preceding claims, wherein the haze of the sheet is at most 5%, preferably less than 5%.

4. The polyamide molding composition as claimed in any of the preceding claims, wherein the haze of the sheet is at most 4%, preferably at most 3%.

5. The polyamide molding composition as claimed in any of the preceding claims, wherein the notched impact resistance of the sheet is at least 14 kJ/m2, preferably more than 14 kJ/m2, particularly preferably more than 15 kJ/m2.

6. The polyamide molding composition as claimed in any of the preceding claims, wherein the yellowness index of the sheet is less than 3, preferably less than 2.5, and particularly preferably less than 2.

7. The polyamide molding composition as claimed in any of the preceding claims, wherein the light transmittance of a sheet of thickness 2 mm produced from the transparent homopolyamide and/or copolyamide is at least 90%.

8. The polyamide molding composition as claimed in any of the preceding claims, which is free from photochromic dyes.

9. The polyamide molding composition as claimed in any of the preceding claims, wherein the solution viscosity (ηrel) of the transparent homopolyamide and/or copolyamide is from 1.3 to 2.0, particularly preferably from 1.40 to 1.90, and/or its glass transition temperature Tg is above 90° C., preferably above 110° C., particularly preferably above 130° C.

10. The polyamide molding composition according to any of the preceding claims, wherein the solution viscosity (ηrel) of the polyesteramide is more than 1.3, preferably more than 1.4, particularly preferably from 1.45 to 2.0.

11. The polyamide molding composition as claimed in any of the preceding claims, wherein the solution viscosity (ηrel) difference of hompolyamide and/or copolyamide and polyesteramide is less than 0.4, preferably less than 0.3, or less than 0.2.

12. The polyamide molding composition as claimed in any of the preceding claims, wherein the glass transition temperature of the polyesteramide is less than 40° C., preferably less than 25° C., with particular preference less than 0° C., particularly preferably in the range from (−60) to −(−20)° C.

13. The polyamide molding composition as claimed in any of the preceding claims, wherein the modulus of elasticity of the polyesteramide is less than 500 MPa, preferably less than 300 MPa, particularly preferably less than 200 MPa.

14. The polyamide molding composition as claimed in any of the preceding claims, wherein the melting point of the polyesteramide is in the range from 100 to 220° C., preferably from 100 to 180° C., particularly preferably from 100 to 160° C.

15. The polyamide molding composition as claimed in any of the preceding claims, wherein the polyesteramide is a block copolymer.

16. The polyamide molding composition as claimed in any of the preceding claims, wherein the polyesteramide is a block copolymer based on a polyamide with a long-chain diol and/or polyesterdiol, preferably a dimerdiol, particularly preferably a C36 dimerdiol.

17. The polyamide molding composition as claimed in claim 16, wherein the block copolymer also contains dimerdiol dimerate, particularly preferably C36 diol dimerate.

18. The polyamide molding composition as claimed in claim 16 or 17, wherein the block copolymer also contains an aromatic acid, particularly preferably terephthalic acid.

19. The polyamide molding composition as claimed in any of the preceding claims, wherein the basis on which the polyesteramide has been formed comprises an amount in the range from 35 to 45% by weight of laurolactam, from 30 to 40% by weight of dimerdiol, preferably C36 dimerdiol, from 5 to 15% by weight of dimerdiol dimerate, particularly preferably C36 diol dimerate, and also from 5 to 15% by weight of terephthalic acid.

20. The polyamide molding composition as claimed in any of the preceding claims, wherein the proportion present by weight of the transparent homopolyamide and/or copolyamide is from 80 to 98% by weight.

21. The polyamide molding composition as claimed in any of the preceding claims, wherein the proportion present by weight of the polyesteramide is from 2 to 20% by weight.

22. The polyamide molding composition as claimed in any of the preceding claims, wherein the proportion present by weight of the polyesteramide is from 5 to 15% by weight.

23. The polyamide molding composition as claimed in any of the preceding claims, wherein the transparent hompolyamide and/or copolyamide is an amorphous or microcrystalline transparent polyamide, preferably with modulus of elasticity of more than 1000 MPa.

24. The polyamide molding composition as claimed in any of the preceding claims, wherein the transparent homopolyamide and/or copolyamide is a polyamide based on aliphatic, cycloaliphatic, or aromatic diamines, on dicarboxylic acids, on lactams, and/or on aminocarboxylic acids, preferably having from 6 to 36 carbon atoms, or is a mixture of these homopolyamides and/or copolyamides.

25. The polyamide molding composition as claimed in claim 24, wherein the cycloaliphatic diamines are MACM, IPD and/or PACM, with or without addition or substituents.

26. The polyamide molding composition as claimed in claim 24 or 25, wherein the aliphatic dicarboxylic acid is an aliphatic dicarboxylic acid having from 2 to 36, preferably from 8 to 20, carbon atoms in linear or branched arrangement, particularly preferably having 10, 12, 14, 16, or 18 carbon atoms.

27. The polyamide molding composition as claimed in any of claims 24 to 26, wherein the transparent polyamide is a homopolyamide selected from the group of MACM12, MACM14, MACM16, MACM18, PACM12, PACM14, PACM16, PACM18, and/or is a copolyamide selected from the group of MACM12/PACM12, MACM14/PACM14, MACM16/PACM16, MACM18/PACM18, or is a mixture of these polyamides.

28. The polyamide molding composition as claimed in any of claims 24 to 27, wherein the transparent homopolyamide and/or copolyamide is a polyamide based on aromatic dicarboxylic acids having from 8 to 18, preferably from 8 to 14, carbon atoms, or is a mixture of these homopolyamides and/or copolyamides, preferably based on PXDA and/or MXDA, particularly preferably based on lactams and/or on aminocarboxylic acids, where the aromatic dicarboxylic acids are preferably TPA, naphthalenedicarboxylic acid, and/or IPA.

29. The polyamide molding composition as claimed in claim 28, wherein the transparent homopolyamide and/or copolyamide is a polyamide selected from the group of: MACM9-18, PACM9-18, MACMI/12, 6I/6T/MACMI/MACMT/12, 3-6T, 6I6T, TMDT, 6I/MACMI/MACMT, 6I/PACMI/PACMT, 6I/6T/MACMI, MACMI/MACM36, 6I; 12/PACMI or 12/MACMI, 12/MACMT, 6IPACMT, 6/6I, 6/IPDT, or a mixture thereof, where 50 mol % of the IPA can have been replaced by TPA.

30. The polyamide molding composition as claimed in any of the preceding claims, wherein the additives are stabilizers, such as non-photochromic dyes, e.g. UV absorbers, UV stabilizers, heat stabilizers, lubricants, for example paraffin wax or stearates, fillers, or free-radical scavengers, and/or are processing aids, plasticizers, reinforcing materials, e.g. transparent-dispersion nanoparticles or glass beads or glass fibers, further polymers, transparent polyamides, and/or nylon-12, and/or are functional additives preferably for influencing optical properties, for example particularly refractive index, or are a combination or mixture thereof.

31. The polyamide molding composition as claimed in any of the preceding claims, wherein the polyesteramide is a block copolymer based on hard nylon-12 segments with soft C36 dimerdiol segments.

32. A transparent article with at least one region or one layer composed of a polyamide molding composition as claimed in any of the preceding claims.

33. The article as claimed in claim 32, which is a foil, a molding, a profile, a tube, a hollow body, or an optically variable filter, or an optical lens, and preferably is an ophthalmic lens, and particularly preferably is an element with spectral filter effect, for example in the form of spectacle lens, sun lens, corrective lens, optical filter, ski goggles, visor, safety spectacles, photorecording, display, optical data storage, or window in buildings or in vehicles, or is a decorative element or a structural element, e.g. in the form of a spectacle frame, toy, or in the form of part of a sports shoe, or cover, in particular in the form of a mobile-telephone casing, a part of electronic equipment, a coating, in particular of packaging, of decorative items, or of sports equipment, or cladding, preferably in the automobile sector.

34. The article as claimed in either of claims 32 and 33, which has a color gradient, an antireflective coating, a scratch-resistant coating, an optical-filter coating, a polarizing coating, an oxygen-barrier coating, or a combination of these coatings.

35. The article as claimed in any of claims 32 to 34, wherein the glass transition temperature of the region or the layer composed of the polyamide molding composition is above 90° C., preferably above 100° C., particularly preferably above 130° C.

36. A process for preparation of a polyamide molding composition as claimed in any of claims 1 to 31, which comprises mixing the homopolyamide and/or copolyamide, and also the polyesteramide in the form of pellets and molding them in an extruder with melt temperatures in the range from 220 to 350° C. to give an extrudate and chopping with suitable pelletizers to give pellets, preferably using a melt filter on the extruder to remove contamination from molding compositions for transparent moldings, suitable melt filters being those that can be constructed from sieves in sheet form or in the form of candle filters, with the possibility, during the compounding process, of adding additives which are desirable for modification of the molding composition, e.g. processing stabilizers, color pigments, UV absorbers, heat stabilizers, flame retardants, other transparent polyamides, or nylon-12.

37. A process for production of an article as claimed in any of claims 32 to 35, which comprises molding a polyamide molding composition as claimed in any of claims 1 to 31 in an extrusion process, in an injection-blow-molding process, in an injection-molding process, or in an in-mold-coating process, to give the article.