AU751426B2 - Polyamide composition - Google Patents

Description

AUSTRALIA

Patents Act COMPLETE SPECIFICATION

(ORIGINAL)

Application Number: Lodged: Class Inst. Class Complete Specification Lodged: Accepted: Published:

S.

Priority

*O*

S Related Art: Soo: Applicant(s): 0 CIBA SPECIALITY CHEMICALS PTY. LTD.

S

SAddress for Service is: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street 0 Melbourne 3000 AUSTRALIA Complete Specification for the invention entitled: Complete Specification for the invention entitled: "POLYAMIDE COMPOSITIOI IP AUSTRALIA

RECEIVED

2 5 NOV 1998

MELBOURNE

Our Ref.: IRN 515190 The following statement is a full description of this invention, including the best method of performing it known to applicant(s): POLYAMIDE COMPOSITION This invention relates to a new polyamide formulation and to products formed therefrom.

Background Polyamide polymers are well known for their durability, resistance to chemical attack and stability. Nylon 6 and Nylon 12 are particular polyamides which are used extensively in industry in extrusion and other moulding processes.

The present invention is particularly concerned with pigmented polyamide formulations suitable for use in extrusion or other moulding processes.

Pigmented polyamides may be utilised in extrusion coating,.such as for cables or for the formation of pipes or tubes where it is desired that the polyamide layer or coating be of a particular colour. In the car industry polyamides are often used for moulding interior and exterior components. Previous formulations utilised in preparing pigmented polyamides have in the past suffered from a significant Sdisadvantage in that products formed therefrom have tended to yellow or change colour over time particularly when exposed to high temperatures over long periods. Pipes exposed to the sun and moulded pigmented polyamide parts housed under the bonnet of a motor car are examples of products which have 20 been found wanting because of this disadvantage. There are many other S instances where the yellowing or fading of pigmented polyamides has been considered problematic in the past.

In the car industry discolouration is considered to be such a significant problem that moulded polyamide articles for use in under-bonnet applications are :i 25 often spray painted in preference to using or relying on a pigmented polyamide in the formulation. This is labour intensive and costly. Further there is a relatively high rejection rate (about 10%) due to difficulties in correctly and uniformly spray painting the articles concerned. Rejects are not recyclable due to the paint.

It is thus an object of the present invention to provide a polyamide formulation suitable for use in extrusion or other moulding processes which is pigmented but which is more resistant to colour variation than presently available L formulations particularly when exposed to higher temperatures over an extended period of time.

Summary of the Invention In a first aspect of the present invention there is provided a polyamide formulation suitable for use in extrusion or other moulding processes which includes: one or more polyamides; at least one long term anti-oxidant which is preferably a hindered phenolic anti-oxidant; at least one phosphite anti-oxidant; and optionally one or more further components such as fillers, reinforcing fibres, pigments or lubricants. The hindered phenolic anti-oxidant does not generally contain nitrogen which we have found generally exacerbates colouring. Typically the hindered phenolic anti-oxidant is of formula I: .0 0 HO O (CH 2 )n-C-O (R 1 0)m-C-(CH 2 n

OH

R R 15

I

wherein R are independently selected lower alkyl particularly branched lower-alkyl such as tert-butyl; n is from 1 to 3 and preferably 2;

R

1 is ethylene or propylene and preferably ethylene; 20 m is from 1 to 5 and preferably 3.

The most preferred hindered phenolic anti-oxidant is ethylenebis(oxyethylene)bis [(5-tert-butyl-4-hydroxy-m-tolyl)propionate. This compound has the formula la.

H

3

C

0 HO

(CH

2 2

O-CH

2 CH20CH 2 Ia

(CH

3 3

C

The compound of formula la is commercially available from Ciba under the trade mark "IRGANOX 245". Typically the amount of hindered phenolic antioxidant present in the composition will be at least 0.05% and preferably no more than 2% by weight of the total composition. Most preferably the hindered phenolic anti-oxidant is present in an amount of from 0.15 to 1% by weight of the total composition.

Examples of suitable phosphite anti-oxidants are: Phenol,2,-bis(1,1-dimethyl)-phosphite (known by the trade mark IRGAFOS 168); (ii) Phosphorous acid, [1,1'-biphenyl]-4,4'-diylbis-, tetrakis-[2,4-bis(1,1dimethylethyl) phenyl]ester (known by the trade mark IRGAFOS PEPQ); (iii) 2[{2,4,8,10-tetrakis(1,1 -dimethylethyl)dibenzo[d,f]{1,3,2}dioxaphos phepin-6-}oxy]-N,N-bis[{2,4,8,10-tetrakis(1,1 -dimethylethyl)dibenzo[d,f] 15 {1,3,2}-dioxaphosphepin-6-y}oxy]-ethyl]ethanamine (known by the trade mark IRGAFOS 12); (iv) bis[2,4-bis(1,1-dimethylethyl)-6-methylphenyl]ethylester, phosphorous acid (known by the trade mark IRGAFOS 38); and BIS (2,4 Ditert-Butylphenyl) Pentaerythritol Diphosphate (known by the 20 trade mark ULTRANOX 626) /C(CH3)3 H2 H 2

(CH

3 3 C (CH3)3 C-O_ p-0 C(CH 3 3 O0-H 2 C CH 2

-O

These phosphites will be referred to by the trade marks indicated above.

Preferably the phosphite anti-oxidant does not contain nitrogen. We have proved that phosphite which do not contain nitrogen are generally more effective in reducing colouring of polyamides.

The phosphite anti-oxidant component is typically present in the polymeric formulation in an amount of at least 0.1% by weight and typically it is not necessary to use more than about 5% by weight.

It is preferred that phosphite anti-oxidants be present in the polymeric formulation in an amount of between 0.5% to Preferably the phosphite anti-oxidant component is capable of inhibiting e the propagation of oxidizing free radical chain reactions with the one or more polyamides during extrusion or other moulding processes at temperatures between 200-3000C. Most preferably between 250-275 0

C.

The more preferred phosphate anti-oxidants are compounds of formula II.

R

1 -P O R 2 R2 2 wherein R 1 is alkyl preferably C, to C, alkyl and most preferably ethyl and

R

2 is independently selected from lower alkyl and most preferably are t-butyl.

IRGAFOS 38 is the most preferred phosphite.

The weight ratio of hindered phenolic to phosphite anti-oxidant is preferably in the range of from 1:2 to 1:10 and most preferably is about 1:4.

Preferred polyamides are Nylon-6 (polycaprolactam), Nylon-6,6 (polyhexamethylene adipamide), Nylon-6,9 (polyhexamethylene azelaamide), Nylon-6,10 (polyhexamethylene sebacamide), Nylon 6-12 (polyhexamethylene dodecanoamide), Nylon-11 (polyundecanoamide) and Nylon 12 (polydodecanoamide). The formulation can contain one or more additional polymers which are not polyamides (such as olefins) but preferably does not.

The filler or filler component when present may be of any of the pigments known in the art for use in plastics. Examples of pigments include platelette pigments such as mica and alumina and rhombic segments such as titanium dioxide, zinc oxide and zinc sulfate. A mixture of pigments may be used if desired.

The polyamide composition of the invention preferably contains a fibrous filter partially glass in an amount of at least 5% by weight and more preferably in an amount of from 1 to 30% by weight.

In multipigmented pearl compositions is particularly advantageous to Sfurther include a bis-benzoxazole brightener such as UVITEX FP.

In a preferred embodiment the composition of the invention further includes at least one optical brightener which is preferably a bis-benzoxazole.

We have found that when an optical brightener is used the total amount of phosphite anti-oxidant which needs to be utilised to maintain resistance to colour variation in the pigmented polyamide generally can be reduced. Preferably the optical brightener is resistant to degradation at the temperatures utilised in moulding or extruding the polymeric formulation.

The benefit of using a brightener is particularly evident when the pigment contains platelet particles. The combination of brightener with mica is particularly advantageous. The preferred brighteners are bis-benzoxazoles. A suitable example of bisbenzoxazole optical brightener is 4,4"-bis(2-methoxystyryl)-1,1'-biphenyl-which is known by the trade mark UVITEX FP. It is preferred that an optical brightener 15 be present in the polymeric formulation in an amount between 0.005 to 0.05% by weight and more preferably 0.001 to 0.05% by weight. Most preferably in an amount of about 0.02%. In such a formulation it is preferred that the phosphite anti-oxidant(s) be present in an amount of from 0.40% to 0.80% by weight of the formulation.

20 It has been found that particularly good resistance to fading and yellowing *..has been achieved in end products when the formulation includes UVITEX FP, a hindered phenolic of fdrmula I such as IRGANOX 245 and a phosphite such as IRGAFOS 168, IRGAFOS 38 or ULTRANOX 626.

In a second aspect of the present invention there is provided a polyamide 25 formulation suitable for use in extrusion or other moulding processes which includes:one or more polyamides; at least one pigment; at least one process stabilising anti-oxidant which is preferably a phosphite; at least one long term anti-oxidant; and optionally at least one optical brightener which is preferably a bis 'Oenzotriazole and which at least one of the anti-oxidants is a phosphite and wherein phosphite anti-oxidants are present in the polymeric formulation in an amount by weight of 0.25% or greater.

It is preferred that phosphite anti-oxidants be present in the polymeric formulation in an amount of between 0.5% to Preferably each of the process stabilizing anti-oxidants are phosphites capable of inhibiting the propagation of oxidizing free radical chain reactions with the one or more polyamides during extrusion or other moulding processes at temperatures between 200 3000C. Most preferably between 250 2750C.

Examples of preferred process stabilizing phosphite anti-oxidants are phosphite anti-oxidants to (iii) referred to above.

In a particularly preferred embodiment of the second aspect of the invention the process stabilizing anti-oxidant includes IRGAFOS 12 present in the polymeric formulation in an amount of between 0.10% to 0.35% by weight together with an additional phosphite anti-oxidant in an amount of between 0.20% 15 to 0.75% by weight. Alternatively, IRGAFOS 12 may be utilized as the only phosphite anti-oxidant and in such a formulation is preferably present in an amount of between 0.40% to 0.80% by weight.

The long term anti-oxidant should be capable of surviving those conditions *o o normally associated with polyamide extrusion or other moulding processes. This 20 generally means that it is desirable that the long term anti-oxidant will not sacrifice itself to oxidation at temperatures of between about 250 2750C when exposed over time periods in the order of 4 to 5 minutes. Most preferably the long term anti-oxidants are hindered phenolics.

Examples of suitable long term anti-oxidants for use in the second aspect of the invention are: hindered phenolics e.g. benzenepropanamide,N,N'-1,6-hexanediylbis[3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy-(9CI) (known by the trade mark IRGANOX 1098); (ii) hindered amines e.g. those known by the trade marks CHIMASSORB 119 and Chimassorb 944.

The long term anti-oxidant(s) are preferably present in the polymeric formulation in an amount by weight of between 0.15% to In one embodiment of the invention the long term anti-oxidant is present in an amount of between 0.15% to 0.75% by weight and is used in conjunction with other antioxidants such that phosphite anti-oxidants are present in the total formulation in an amount of between 0.40% to 0.80% by weight. Most preferably, in such an embodiment IRGAFOS 12 is utilized as the, or one of, the phosphite antioxidants.

The formulation can contain one or more additional polymers which are not polyamides (such as olefins) but preferably does not. A suitable optical brightener for use in the second aspect of the invention is also 4,4"-bis(2methoxystyryl)-1,1'-biphenyl- which is known by the trade mark'UVITEX FP. It is preferred that an optical brightener be present in the polymeric formulation in an amount between 0.01% to 0.05% by weight. Most preferably in an amount of about 0.02%. In such a formulation it is preferred that the phosphite anti- 15 oxidant(s) be present in an amount by weight in the formulation of between 0.40% S. to 0.80%. In the second aspect of the invention it is preferred to utilize IRGAFOS 12 in an amount by weight of between 0.15% to 0.35% with an additional phosphite anti-oxidant. Most preferably the additional phosphite is or includes IRGAFOS PEPQ.

20 It has been found that particularly good resistance to fading and yellowing has been achieved in end products when the formulation includes both UVITEX FP and IRGAFOS 12.

In all embodiments of the invention hereinbefore described it is desirable to include a processing lubricant. Any suitable compound known in the art may be 25 utilised. However, it is preferred to utilize sodium stearate in an amount of about The polyamide used is preferably nylon 6 and any of the conventional pigments utilised in pigmenting polyamides may be used in the practice of the present invention.

The invention is hereinafter described with reference to some examples of polymeric formulations in accordance with the present invention which have been found to be particularly resistant to fading and discolouration.

These examples are preferred embodiments of the invention and are not to be construed as limiting the scope of the invention as hereinbefore described.

8 Examples Examples 1-33 Preparation, oven-ageing and colourimetric measurement of monopigmented glass-filled Nylon-6 plaques.

Examples of monopigmented glass-filled Nylon-6 plaques have been prepared at 285C, containing different anti-oxidant systems.

The ingredients and amounts thereof (in parts by weight) of each of the composition Examples 1 to 33 are shown in tables la to 1d.

The chemical composition of the additives is shown in the glossary at the end of the Examples.

609 s*e.*

O*

O

o° ft S o C 6 go 6 0* go. 0 9 *0 CS 4

S

6 0 *Oe Oge eS 0 -9- Table 1Ia 0 0 4 4 5 0 *e a g C 006 0 9 CO A *0 600 0 0 C S gte.

0* 0 000 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Materials Used (g) Pigment White 5,7 10 10 10 10 10 10 10 10 10 10 10 10 10 Pigment White 6 Nylon-6 386 386 386 386 386 386 386 386 386 386 386 386 386 386 386 IRGANOX 245 0.8 0.8 0.8 0.8 0.8 0.8 IRGANOX 1076 0.8 0.8 0.8 IRGANOX L06 0.8 IRGANOX HP241 1 4 IRGANOX LC71 3.2 IRGANOX PS800 IRGAFOS PEPQ 3.2 3.2 3.2 IRGAFOS 168 3.2 3.2 3.2 2 IRGAFOS 38 3.2 3.2 3.2 CuI/KI/Zn St UVITEX FP 0.1 0.1 0.1 4

U.

~6 0 0* 4 a )hd0 0 04 a. a 0* 0. 0 a a.

Sb @0

S

0 0 000004 0 d 0 0~ 0i Table lb 16 17 178 19 Materiais Used (g) Pigment White 5,7 10 10 10 10 Nylon-6 385 385 385 385 385 IRGANOX 245 1 1 1 IRGANOX 1076 1 IRGAFOS PEPQ 4 IRGAFOS 168 4 4 IRGAFOS 38 4 IRGANOX LC71 UVITEX FP Table 1Ic 21 22 23 24 25 26 Materials used (g) Pigment White 5,7 10 10 10 10 10 Nylon-6 384 384 384 384 384 384 IRGANOX 245 1.2 1.2 1.2 IRGANOX 1076 1.2 IRGAFOS PEPQ 4.8 3 IRGAFOS 168 4.8 4.8 IRGAFOS 38 4.8 IRGANOX LC71 3 UVITEX FP 0.2 Table Id 27 28 29 30 31 32 33 Materials used (g) Pigment White 5,7 10 10 10 10 10 10 Nylon-6 384 384 384 384 384 384 384 IRGANOX 245 0.8 0.8 0.8 0.8 0.8 0.8 0.8 IRGANOX HP136 1.3 EP C:\WNhWORD\ELLEN\SPECIRLE\IRS4OO74.DOC 00 4 6 0000 0 600066 )0 0 00 0000 ow 00 0 0 IRGANOX 168 3.2 GSY-P101 3.2 DOVERPHOS S-9228 3.2 PEPQ 3.2 ULTRANOX 626-A 3.2 SEENOX 412S 3.2 CYANOX 1790 3.2 The anti-oxidants, lubricating agent and pigment were mixed as a dry powder with polymer granules until the granules were seen to be uniformly coated.

The homogeneous dry powder blend was then injection moulded into plaques of about 7.0 cm by 0.35 cm thick and aged in thermostatically controlled oven at 170 0 C for 24h.

The chips were then allowed to cool to room temperature and measured for their colour characteristics in reference to unexposed specimens. In this regard the 10 'colour difference' data was generated as shown in Table 2.

Table 2 Colourimetric values for corporation examples 1 to 26 After oven aging of Corporation Examples 1 to 26, the plaques were individually measured for their colour values in comparison with 'unaged' samples.

The colourimetric values for batches 1 to 26 are shown in Table 2 and are averaged values taken from measurements of at least 12 oven-aged plaques.

Batch Number Additive(s) DL DA DB DE Additive(s) 1 IRGANOX 245/4 IRGAFOS -5.9 1.4 17.7 22.1

PEPQ

2 IRGANOX 245/4 IRGAFOS 168 -5.1 1.4 16.1 19.9 3 IRGANOX 245/ 4 IRGAFOS 38 -4.9 1.1 13.1 15.9 4 IRGANOX 1076/4 IRGAFOS 168 -12.3 5.3 28.7 35.9 IRGANOX 245/ 4 IRGAFOS -9.4 1.7 27.8 34.6 PEPQ 0.125 UVITEX FP_ EP C:WINWORD\ELLEN\SPECIRLEIR540074.DOC .0 0 0 00 0000 0 0000 0 000000 0 0000 0 0000 0000 S 0 00 0 00 00 0 00 0000 00 00 0 0 000000 0 0000..

0 00 0 0 000 0 @00 0 0 S 0 00 6 IRGANOX 245/ 4 IRGAFOS 168 -6.9 0.7 20.6 25.9 0.125 UVITEX FP 7 IRGANOX 245/ 4 IRGAFOS 38 -6.2 -0.2 23 28.5 0.125 UVITEX FP 8 IRGANOX 1076/ 4 IRGAFOS 168 -12.9 3.9 34.7 41.9 0.125 UVITEX FP 9 CuI/KI/Zn stearate* -14 5.4 10.6 11.5 IRGANOX L06 -29.5 6.1 22.8 32.2 11 Pigment White 6 -34.9 14.6 24.5 36.8 12 Pigment White 5,7 -41 18.7 26.7 41.2 13 IRGANOX LC7I/IRGAFOS -14.6 6.4 22.4 29.8

PEPQ

14 IRGANOX 245/ 4IRGANOX -25.7 11.9 27.8 37.3 PS800 15 IRGANOX 245/ 4IRGANOX -20.5 9.1 12.8 16 HP2411 1.25% Additive(s) 16 IRGANOX 245/ 4 IRGAFOS -9.8 3.3 27.7

PEPQ

17 IRGANOX 245/ 4 IRGAFOS 168 -5.6 0.8 19 23.2 18 1IRGANOX 245/ 4I1RGAFOS 38 -3.8 0.4 11.8 14.5 19 IRGANOX 1076/ 4 IRGAFOS 168 -9.7 3.2 26.4 32.9 IRGANOX LC71/ 4 IRGAFOS -13.5 5.8 20.2 26.7

PEPQ

1.5% Additive(s) 21 IRGANOX 245/ 4 IRGAFOS -5.7 0.9 18.9 23.7

PEPQ

22 IRGANOX 245/ 4 IRGAFOS 168 -4.8 0.4 17.8 21.7 23 IRGANOX 245/ 4 IRGAFOS 38 -3.7 0.4 10.81 13.3 24 IRGANOX 1076/ 4 IRGAFOS 168 -10 3.5 27.3 33.7 IRGANOX LC71/ 4 IRGAFOS -14.7 0.4 20.6 27.7

PEPQ

26 IRGANOX 245/ 4 IRGAFOS 168 -6.2 -0.3 23.7 29.8 0.125 UVITEX FP 27 IRGANOX 245/ 4GSY-PO1 -9.4 -3.2 23.9 30.4 EP C:%WNORDELLEN\SPECIRLEJR54O74.DOC 28 IRGANOX 245/4 DOVERPHOS -7 1.4 22.7 27.8 S-9228 29 IRGANOX 245/4 PEPQ -11.1 -4.4 27.5 33.6 IRGANOX 245/4 ULTRANOX -2.7 -0.4 11.8 14.6 626A 31 IRGANOX 245/4 IRGAFOS 168/2.1 -9.9 4.6 24.2 27.2 HP 136 32 IRGANOX 245/4 SEENOX 412S -34.6 16.2 28.1 42.3 33 IRGANOX 245/ 4 CYANOX 1790 -32 9.2 18.1 26.5 The degree of colour change is quantified in terms of DL, DA, DB, DE S" where DL =the colour difference in light/dark values, DA the colour difference in 0 I0 red/green values, DB= the colour difference in yellow/blue values and DE the 060900 S 5 total colour difference. All values have been reported in CMC:2 units under illuminant 100 observer, specular included.

Discussion of colourimetric values for Comparative Examples 1 to 33 From the colourimetric values shown in tables 1 and 2 it is evident that 10 combinations of primary phenolic anti-oxidants with secondary phosphite antioxidants exhibit effective protection against polyamide discolouration.

In particular, phosphites with a basic structure of :{[2,4-tert-butyl-C 6

H

4

-O]

2 P-OR, where R= an aliphatic or aromatic group) appear to be the best secondary anti-oxidants for arresting colour deterioration. In particular, comparison of 15 colourimetric values of batches 21-23 implicate IRGAFOS 38 as the most effective secondary anti-oxidant. Furthermore, comparison of the colourimetric measurements for batch 80 with batch 78, suggests that IRGANOX 245 is a more effective primary anti-oxidant for use in 14% glass-filled Nylon.

The optimum anti-oxidant combinations were found to be in order of IRGANOX 245/4 IRGAFOS 38, 1% IRGANOX 245/4 ULTRANOX 626A, 1.25% IRGANOX 245/4 IRGAFOS 38, 1% IRGANOX 245/4 IRGAFOS 38 and 1% IRGANOX 245/4 IRGAFOS 168.

In the case of IRGANOX 245 with IRGAFOS 38 and 168 (batches 2, 3), EP C:\WlNWORD\ELLEN\SPECIRLElIR540074.DOC (18, 19), (23, 24), there was an improvement in colour characteristics as the concentration of the secondary anti-oxidant was increase. Conversely, an increase in the concentration of PEPQ with IRGANOX 245 (batches 1, 16, 27) did not markedly improve the resistance to discolouration. In the case of IRGANOX LC71/IRGAFOS PEPQ (batches 13, 20, 25), an increase in anti-oxidant concentration caused a deterioration in colour characteristics.

IRGANOX HP2441 and HP136 are examples of lactone/phenolic/phosphite and lactone anti-oxidants respectively whereas KI/Cul/Zinc stearate is an inorganic triblend anti-oxidant.

Comparison of batch 2 with 31 indicates that the effect of adding the lactone IRGANOX HP 136, is to exacerbate discolouration. Similarly, comparison of examples 1 to 3 with 15 suggests that the triblend IRGANOX HP2411 HP-135, 42.5% IRGAFOS 168, 42.5% IRGANOX 3114) does not perform as effectively as a single phosphite anti-oxidant.

15 Colourimetric measurements of the inorganic anti-oxidant, Example 9, shows impressively low DB and DE values but a high DL value. It is proposed that the initial greenish-yellow colour of these plaques hides the yellowing which leads to a small total colour difference.

These examples, 5 to 8, sought to determine the effect of using the optical 20 brightener UVITEX FP and to 11 12 to examine the effect with whites Pigment White 6 and Pigment White 5,7. Comparison of Examples 1 to 4 with Examples to 8 indicates the UVITEX FP leads to a deterioration in DL, DA, DB and DE.

However when used in a multi-pigmented pearl system, the optical brightener was seen to improve the colourimetric and visual properties even though in the 25 final assessed article it had been already destroyed by the oven ageing.

Titanium dioxide as a whitening pigment showed significantly less discolouration with oven ageing compared with an equivalent amount of Pigment White 5,7 in glass-filled Nylon-6.

ULTRANOX 626A performed as well in colourimetric measurements. The other Doverphos S-9228, GSY-P101, PEPQ, SEENOX 412S and Cyasorb 1790 all performed relatively poorly in comparison with secondary phosphites SIRGAFOS 38, 168 and PEPQ.

S TM W:\Tanla515190 spedclean.doc Visual colour assessment of mono-pigmented, oven aged plaques In addition to using colourimetric measurements to evaluate the performance of additives in oven-aged plaques, visual assessments were also performed.

From a survey of 10 persons, trained and untrained colour people (5 males and 5 females), the formulations 1 to 33, were studied for discolouration compared to the unaged standards.

Table 3 includes 6 plaques deemed visually to be have the closest colour characteristics to their respective unaged standards. The numbers of 1 st s 2 n d s 10 3 rd s and 4 th s correspond to the number of people who rank a given plaque in that position.

Of 10 people surveyed a wide range in visual assessments were given.

Some participants could only distinguish 2 'visually good' plaques whereas others could distinguish 3 or 4 'good plaques' in terms of their closeness to an unaged standard.

Table 3 Visual assessments made of the 'visually best' plaques

S

*r 5

*C

C

'9.

Batch Composition Concentration of additive 1st 2nd 3rd 4th 245/4 38 1.25 4 0 2 0 95 245/4 38 1.5 3 6 0 0 75 245/438 1 2 3 3 1 78 245/4168 1 1 0 0 1 74 245/4168 1 0 1 0 0 73 245/4 PEPQ 1 0 0 0 1 EP C:\WINWORDELLEN\SPECIRLElJR540074.DOC 16 Evidently these visual assessments rank batch 90 and 95 as plaques most resistant to discolouration. The 'visually best' plaques, in order of performance include: 245/4 38 245/4 38 245/4 38 245/4 168 0.125 FP 245/4 168 and 245/4 PEPQ These 'visual assessments' closely agree with the colourimetric measurements described in 3.1 The uncertainty amongst people surveyed in determining whether 245/4 38 is better than 245/4 38 is not surprising considering different people perceive colours in different ways.

Therefore in selecting the best additive package against discolouration it is paramount to consider both the colourimetric and visual assessments.

Examples 34 to 39 Preparation, oven-aging and measurement of multi-pigmented systems Six batches of plaques were prepared containing a number of best performing Examples described above and were combined with aluminium pigment (SILVET), titanium dioxide (Pigment White 6) and sodium stearate. The composition of each of the batches 34 to 39 is shown in Table 4. After oven ageing at 170C for 22h the discolouration of plaques was determined from colourimetric measurements, as shown below.

S20 Table 4 99* 9 0 9* .9 9 9.

oo• go Sample 34 35 36 37 38 39 Pigment White 6 1.6 1.6 1.6 1.6 1.6 1.6 Sodium Stearate 0.8 0.8 0.8 0.8 0.8 0.8 IRGANOX 245 1.2 1.2 1.6 1.6 1.2 IRGAFOS 38 4.8 6.4 4.8 IRGAFOS 12 4.8 ULTRANOX 626A 4.8 6.4 IRGANOX 1010 1.2 SILVET 6 6 6 6 6 6 CAPRON 8312 386 386 383.6 383.6 386 386 DL -0.8 0.2 -0.2 1.0 1.8 0.6 DA -0.5 -0.2 -0.1 -0.1 -0.3 -0.2 DB 2.0 0.8 0.7 0.6 1.7 0.8 DE 2.9 1.2 1.0 1.0 2.5 1.3 EP C:\WINWORD\ELLEN\SPECIRLER540074.DOC

C

C

C

C CC* Ce 9. 9*

C

S

C

*0 C C

C

C

'C

17 Examples 40-50 Preparation, oven-ageing and measurement of 'Pearl' based multipigmented systems containing various additive systems.

The evaluation of 'Pearl' based multi-pigmented compositions were prepared as shown in Table 5. The plaques were prepared and measured for their colourimetric values as described in Examples 1-33.

The composition of plaques containing pigmented additive systems with metallic and pearl pigments is shown in table 5. Samples were oven aged 165C for 22h and the colourimetric values are averaged from the measurements of at least plaques. In these trial 2.4% of various additives were used in combination with various pearls and a 'SILVET'.

Table 40 41 42 43 44 45 46 47 48 49 Materials Cl No 77891 40.5 40.5 90.7 40.5 58.1 58.1 CI No 77115 40.5 40.5 40.5 40.5 Cl No 77310 11.1 11.1 11.1 11.1 11.1 11.1 11.1 11.1 11.1 11.1 11.1 Cl No 77266 3.4 3.4 3.4 3.4 3.4 3.4 3.4 3.4 3.4 3.4 3.4 Fine Satin 111 325.1 650.2 325.1 325.1 325.1 325.1 Pearl 151 325.1 325.1 325.1 325.1

IRIODIN

123KU26 650 325.

1 IRIODIN 163 650 325.

1 Sodium 50.7 50.7 50.7 50.7 50.7 50.7 50.7 50.7 50.7 50.7 50.7 Stearate.

PEPQ 120 120 120 120 120 192 LC71 120 120 120 120 120 UVITEX FP 5 5 5 5 5 5 5 5 5 5 SILVET 600 IRIODIN 153 650.2 325.1 IRGANOX 245 48 48 48 48 48 IRGAFOS 168 192 192 192 192 CYANOX 2777 240 Colour Values EP C:\WINWORD\ELLEN\SPECIRLEIJR540074.DOC

C.

4 4

CS,.

4**e *54*4t 4 4CCS S 0 90 C 4* 4* C S. St

C

CC C

S

4***SS

S

C

*CS 950 0 C S.C C *5 4 C C 4 9* DL -2.1 -0.7 -1.9 0.4 -2.2 -0.8 -2.5 -0.8 -1.6 -1.8 DA -0.6 -0.2 -0.7 -0.2 -0.1 -0.6 -0.4 -0.8 -0.9 -0.3 -0.9 DB 7.2 5.1 7.6 1.1 7.8 5.7 9.8 5.8 8.8 7.3 4.4 DE 10.1 7.1 10.2 1.6 11.9 8.8 14.4 8.3 13.4 116.5 From these colourimetric results it is evident that in a multi-pigmented system colouration of the polyamide using 'SILVET', an aluminium-based metallic pigment, is better at restricting discolouration than the pearlescent pigments used.

Examples 51 to Plaques were formed from the compositions of Examples 51 to 55 shown in Table 6. The method use for preparation and colourimetric assessment was as 10 described in Examples I to 33.

Table 6 51 52 53 54 Materials Pig White 6 40.5 40.5 40.5 40.5 40.9 Pig Brown 24 11.1 11.1 11.1 11.1 11.2 Pig Black 6 3.4 3.4 3.4 3.4 3.4 IRIODIN 111 325.1 325.1 325.1 325.1 328.2 MEARL 9110 325.1 325.1 325.1 325.1 328.2 Sodium stearate 50.7 50.7 50.7 50.7 41.6 I RGANOX 245 48 48 48 IRGAFOS 38 192 ULTRANOX 626A 192 IRGAFOS1 68 192 I RGAFOS 122.05

PEPQ

I RGANOX 122.05 246.5 LC71 UVITEXEFP 5 5 5 EP C:\WihWORD\ELLEN\SPECIRLE\MR54OO74.DOC DL -0.6 -1.3 -1.4 -1.6 -3.8 DA -0.6 -0.7 -0.7 0.2 1.3 DB 4 5.1 5.9 9.4 DE 5.7 7.1 8.3 13.9 10.1 The results of colourimetric assessment are visually represented in the following graph.

INHIBITION OF DISCOLOURATION OF PEARLESCENT GLASS- FILLED PA-6 USING NOVEL ANTIOXIDANT SYSTEMS sLO 0 02 Wu

U~

1 DL

*DA

DB

DDE

C

Example The results clearly show the superior results obtained by using an antioxidant composition which includes a primary oxidant which is a hindered phenolic of Formula I (IRGANOX 245) together with a secondary anti-oxidant which is a phosphite and a sacrificial optical brightener.

Visual assessment of the plaques of Examples 51-53, which performed significantly better than the other compositions was conducted by a panel of five people who rated the plaques by comparison with the respective unaged standard. The results are presented in Table 7.

Table 7 Visual Assessments Additive combination 1st 2nd 3rd 245/438 5 0 0 245/4 ULTRANOX 626 0 5 0 245/2168 0 0

C

TM W:\Tania\55190 sped dean.doc

S

S

S

Example 56 This example provides preferred embodiments of the second aspect of the invention and are not to be construed as limiting the scope of the invention as hereinbefore described.

The relative amounts of the respective materials used in each formulation apart from the polyamide are set out in the Table set out below. In examples A to E these mixtures were compounded into nylon 6 in an amount of 4.1% by weight and then extruded to form moulded pigmented polyamide articles. In examples F and G the mixtures were compounded into nylon 6 in an amount of 5.0% by weight and then extruded to form moulded pigmented polyamide articles.

Table 8 Pigment White 6 40.5 44 44 40.5 44 40.5 40.9 40.8 Pigment Yellow 11.2 12.2 12.2 11.1 12.2 11.1 11.2 11.2 24 Pigment Black 7 3.4 3.7 3.7 3.4 3.7 3.4 3.4 3.4 Pearl Pigment 325. 353.2 353.2 325.1 353.2 325.1 328.2 325.7 (IRIODIN 111) 1 Pearl Pigment 325. 363.2 363.2 325.1 353.2 325.1 328.2 325.7 (MEARL 9110) 1 Sodium Stearate 50.7 50.7 50.7 50.7 50.7 50.7 41.6 41.6 IRGAFOS 168 122 61 IRGAFOS PEPQ 61 91.5 122.0 123.3 IRGANOX LC71 122 122 244.1 91.5 122.0 246.5 123.3 UVITEX FP 5 5 5 IRGANOX 122 B1171 TOTAL 1000 1000 1005 1000 1005 1005 1000 1000 These formulations after being compounded into nylon 6 in the amounts indicated above were extruded and formed into articles. The articles were exposed to a temperature of 170 0 C for 24 hours and the colour variation of the articles as a result of the high temperature exposure was measured in the following areas: DL (darkness/lightness) TM W:\Tanlal515190 sped cean.doc (ii) Da (red/green) (iii) Db (yellow/blue) (iv) DE (overall) The colour variation was measured using the CIE standard colour difference formula CMC 2:1 under Illuminant These results were illustrated on the following graph where each of the articles formed from nylon 6 formulations with the combinations A to G above are indicated by the same letter. The results indicate the variation of the respective visual characteristics of the product after the high temperature exposure from the pre-exposure characteristics.

COLOUR VARIATION BY FORMULA (n

DL

.i Da

DE

Std A B C D E F G In terms of commercial acceptability of product the applicant has determined that of these parameters DL appears to be the most important. In conventional pigmented polyamides tested in the same way DL is generally more than -10, e.g. Std. The exemplified products of the present invention each have a recorded DL variation after 24 hours exposure at 170 0 C of significantly better than In particular those formulations utilizing an optical brightener (formulations B, D, E G) were found to have significantly improved DL retention and in the cases of formulations D E the Da variations were very small as can be seen from the graph. Visually D E were superior in appearance.

TM W:\Tanial515190 sped clean.doc 21a Accordingly the second aspect of the present invention provides pigmented polyamides which are more resistant to colour variation when exposed to elevated temperatures than standard formulations heretofore proposed and which are sufficiently resistant to colour variation to avoid the need for over o* TM W:\Tanial51590 sped dean.doc 22 painting when being used for example in the car industry such as for under bonnet applications.

Trade IRGANOX 245 IRGANOX 1076 IRGANOX HP136 IRGANOX H P2411 0S* '5555 I RGANOX 3114 IRGANOX L06 IRGANOX PS 800 IRGANOX LC71 25 IRGAFOS 12 IRGAFOS P-EPQ GAS Name Ethylenebis(oxyethylene)bis{3-(5-tert-butyl-4-hyd roxy-m-tolyl) propionate Benzenepropanoix acid, 3, 5-bis( 1,1 -dimethylethyl)-4-hyd roxy-, octadecyl ester 5, 7-di-t-butyl-3-(3 ,4 di-methylphenyl)-3H-benzofu ran-2-one 15% HP-136, 85% IRGANOX B225=(1:1 IRGAFOS 168:IRGANOX 3114) 1,3 ,5-Tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1 2,4,6-(1 An alkylated PANA Propanoic acid, 3,3'-thiobis-, didodecyl ester is a di-blend of IRGANOX 1098 and IRGAFOS 12 tris[2-[[2 I 0-tetra-tert-butyldibenzo[d dioxaphosphepin-6-yl]oxy]ethyl]amine Phosphorous acid, 11,1 '-biphenyl]-4,4'-diylbis-, tetrakis-[2,4bis(1 ,1 -dimethylethyl)phenyl]ester bis[2,4-bis(1 ,1 -dimethylethyl)-6-methylphenyl]ethyl ester, phosphorous acid Phenol,2,-bis(1 ,1-dimethyl)-phosphite (3:1) IRGAFOS 38 IRGAFOS 168 TM W:ATania\51 5190 spedj deando 201 Iodide Stabilizer (CuI/KI/ZN st.) CAPRON 8231 UIVITEX FP Pigment 6 (CI No 77891) Pigment White 5,7 SEENOX 412S CYANOX 1790 IRGANOX 1098 IRGANOX 831171 ULTRANOX 626 Is a tri-blend inorganic anti-oxidant from Mallinckrodt containing 80% potassium iodide, 10% copper iodide, and 10% zinc stea rate 14% Glass-filled Nylon-6 4,4'-bis-(2-methoxystyry)-1 1 '-biphenyl, Rutile based titanium dioxide containing a dense alumina silica, organic coating Zinc sulphide/lithopone.

Pentae rth ritol-tetrakis-(3-1 a urylth io prop ion ate) I ,3,5-Tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1 ,3 triazine-2,4,6 benzenepropanamide, N,N'-1 ,6-hexanediylbis[3,5-bis(1 ,1d imethyl-ethyl)-4-hyd roxy-(9CI) Diblend of IRGAFOS 168 and IRGANOX 1098 in a ratio of 1:1 B15 (2,4 Ditert-Butylphenyl) Pentaerythriol Diphosphate 9* 1 Poo.:

I

TM WATanla%515190 sped deanedo

Claims (13)

1. A polyamide formulation suitable for use in extrusion or other moulding processes which includes: one or more polyamides; at least one hindered phenolic anti-oxidant; at least one phosphite anti-oxidant; and at least one pigment; wherein the hindered phenolic anti-oxidant does not contain nitrogen and the ratio of hindered phenolic to phosphite is in the range of from 1:2 to 1:10.

2. A formulation according to claim 1 wherein the hindered phenolic anti- oxidant is of Formula I: 0 R O Oo HO HO-C( n (CH II II OH S 2 -O -(RO)m-C -(CH 2 )n R R I 15 wherein R are independently selected from lower alkyl particularly branched lower-alkyl such as tert-butyl; n is from 1 to 3 and preferably 2; R 1 is ethylene or propylene and preferably ethylene; m is from 1 to 5 and preferably 3.

3. A formulation according to claim 2 wherein the hindered phenolic anti- oxidant is ethylenebis(oxyethylene)bis [(5-tert-butyl-4-hydroxy-m-tolyl)propionate.

4. A formulation according to any one of claims 1 to 3 wherein the amount of hindered phenolic anti-oxidant present in the composition is from 0.05 to 2 percent by weight of the total composition. TM W:\Tanla\515190 spe clean.doc A formulation according to any one of claims 2 to 4 wherein the phosphite anti-oxidant is selected from: Phenol, 2,-bis(1, 1-dimethyl)-phosphite (known by the trade mark IRGAFOS 168; (ii) Phosphorous acid, [1,1 '-biphenyl]-4,4'-diylbis-, tetrakis-[2,4-bix(1 ,1- dimethylethyl) phenyllester (known by the trade mark IRGAFOS PEPO); (iii) 10-tetrakis(1 ,1 -dimethylethyl)dibenzo[d,f]{1 ,3,2}dioxaphos phepin-6-}oxy]-N,N-bis[{2 14,8,1 0-tetrakis(1, 1-d imethylethyl)d ibenzo {1 ,3,2}-dioxaphosphepin-6-y~oxy]-ethyl]ethanamine (known by the trade mark IRGASFOS 12)' (iv) bis[2 ,4-bis(l 11 -dimethylethyl)-6-methylphenyl]ethylester, phosphorous acid (known by the trade mark IRGAFOS 38); and s, 15 BIS (2,4 Ditert-Butylphenyl) Pentaerythriol Diphosphate (known by 6 4 the trade mark ULTRANOX 626) e O 2 S_ 0oo Afruainacrigt n neo lis2t hri h hsht at-xdn0cmoeti0rseti0h0oymrcfruain na muto frm0 %b egh o5.b egt

7. A formulation according to any one of claims 2 to 6 wherein the phosphite anti-oxidant includes a compound of formula II: R1-P--O Og^ 2 2 2 wherein R 1 is alkyl preferably C, to C6 alkyl and most preferably ethyl and R 2 is independently selected from lower alkyl and most preferably are t-butyl.

8. A formulation according to any one of claims 2 to 7 wherein the weight ratio of hindered phenolic to phosphite anti-oxidant is about 1:4.

9. A formulation according to any one of claims 2 to 8 wherein the polyamides include one or more polyamides selected from Nylon-6 (polycaprolactam), Nylon- 6,6(polyhexamethylene adipamide), Nylon-6,9 (polyhexamethylene axelaamide), Nylon-6,10 (polyhexamethylene sebacamide), Nylon 6-12 (polyhexamethylene dodecanoamide), Nylon-11 (polyundecanoamide) and Nylon 12 (polydodecanoamide).

10. A formulation according to any one of claims 2 to 9 which contains a fibrous filler, preferably glass, in an amount of at least 5% by weight and preferably in an amount of from 1 to 30% by weight.

11. A polyamide formulation according to any one of claims 2 to 10 further comprising an optical brightener which is a bis-benzoxazole.

12. A polyamide formulation according to claim 1 which includes a phosphite anti-oxidant in an amount from 0.5% to 1.0% by weight. TM W:\Tania515190 speci clean.doc

13. A polyamide formulation according to claim 12 wherein the process stabilizing phosphite anti-oxidant includes Phenol,2,4-bis(1,1-dimethyl)-phosphite (ii) Phosphonous acid, [1,1'-biphenyl]-4,4'-diylbis-, tetrakis-[2,4-bis(1,1- dimethylethyl) phenyl]ester; and (iii) 2[{2,4,8,10-tetrakis(1,1-dimethylethyl)dibenzo[d,f]{1,3,2}dioxaphos phepin-6-}oxy]-N,N-bis[{2,4,8,10-tetrakis(1,1 -dimethylethyl) dibenzo[d,f]{1,3,2}dioxaphosphepin-6-y}oxy]-ethyl]ethanamine (IRGAFOS 12). (iv) BIS (2,4 Ditert-Butylphenyl) Pentaerythriol Diphosphate (known by the trade mark ULTRANOX 626)

14. A polyamide formulation according to claim 12 or claim 13 wherein either the process stabilizing anti-oxidant includes IRGAFOS 12 present in the polymeric formulation in an amount of between 0.10% to 0.35% by weight together with an additional phosphite anti-oxidant in an amount of between 0.20% to 0.75% by weight, or IRGAFOS 12 is the only phosphite anti-oxidant and is present in an amount of between 0.40% to 0.80% by weight.

15. A polyamide formulation according to any one of claims 13 to 16 further including at least one optical brightener containing 4,4"-bis(2-methoxystyryl)-1,1'- biphenyl- in an amount between 0.01% to 0.05% by weight. 25 16. A polyamide formulation according to any one of the previous claims as herein described with reference to any one of the Examples. DATED: 10 April, 2002 PHILLIPS ORMONDE FITZPATRICK Attorneys for: CIBA SPECIALITY CHEMICALS PTY. LTD. TM W:\TaniaZ51590 speci clean.doc