GB2199824A

GB2199824A - Aromatic diamides and their use as u. v absorbers in polymers

Info

Publication number: GB2199824A
Application number: GB08727976A
Authority: GB
Inventors: Lajos Avar
Original assignee: Sandoz AG
Current assignee: Sandoz AG
Priority date: 1986-12-02
Filing date: 1987-11-30
Publication date: 1988-07-20
Anticipated expiration: 2007-11-30
Also published as: GB2199824B; GB8727976D0

Description

IMPROVEMENTS IN OR RELATING TO ORGANIC COMPOUNDS The invention relates to novel oxalanilides suitable for use as U V absorbers.

According to the invention, there is provided a compound of formula I

in which each R1, independently is selected fran hydrogen, C1,12alkyl, C1-12alkoxy and halogen; R2 has a significance of R1, independently of R1, or R2 is OH, R20 is -CO-OR6 or, when each R1 is hydrogen and R2 is 2C1-4alkoxy, R20 is additionally H; R3 is hydrogen or methyl (more preferably hydrogen); and R6 is hydrogen; unsubstituted C622alkyl, uninterrupted or interrupted by 1 or 2 oxygen atans or C1-22alkyl mono- or di-substituted by OH and uninterrupted or interrupted by 1 or 2 oxygen atoms; provided when each R1 and R2 is hydrogen, then R6 is not hydrogen.

Preferably R20 is -COwOR In this Specification, any group capable of being linear or branched is linear or branched unless indicated to the contrary. In this Specification where a symbol appears more than once in a formula its significances are independent of one another.

Preferably R1 is R1' where R1' is selected from hydrogen, C1-4 alkyl, C1~4 alkoxy and chlorine. More preferably each R1 is hydrogen.

Preferably R2 is R2' where R2' is hydrogen or C1-2alkoxy, preferably in the ortho-position.

Preferably R6 is R4' where R6' is unsubstituted C6-18alkyl, uninterrupted or interrupted by one -O- group or C1-18alkyl monosubstituted by OH and uninterrupted or interrupted by one or two (preferably one) -O- groups.

More preferably R6 is R" where R6 is unsubstituted C6-18alkyl or C1-6alkyl monosubstituted by OH and uninterrupted or interrupted by one or two -O- groups.

Any C1-12alkyl group is preferably C1-8alkyl, more preferably C1-4alkyl, most preferably methyl or ethyl. Any C1-12alkoxy is preferably C1-8alkoxy, more preferably C1-4alkoxy, most preferably ethoxy or methoxy. Preferably any C1-4alkyl is methyl or ethyl and any C1-4alkoxy is ethoxy or methoxy.

Further, according to the invention, there is provided a process for preparing a compound of formula I where R20 is -COCR6 comprising reacting a compound of formula II

with a compound of formula III HO R (III) where the symbols are as defined above, at an elevated temperature.

Compounds of formula II and III can be prepared by known methods from known compounds.

Preferably a process according to the invention is carried out at a temperature of from 50 to 1200 C.

Preferably a process according to the invention is carried out at a pH of from 7 to 9.

For the avoidance of doubt where a range is defined, the numbers defining the range are included in the range.

Further, according to the invention, there is provided a a process for preparing a compound of formula I in which R20 is -OH comprising reacting a compound of formula VI

with a compound of formula VII

at an elevated temperature.

Further according to the invention, there is provided a compound of formula V

where R3 is as defined above, R10 is hydrogen, methyl or ethyl and R11 is -OH or -COOH.

Preferably R10 is R101 where R101 is methyl or ethyl.

Preferably R11 is -COOH.

Still, further according to the invention, there is provided a process for stabilizing a polymeric substrate comprising adding to the substrate a light stabilising amount of a compound of formula I or V defined above.

Compounds of formula I are useful as stabilizers to protect polymer materials against degradation by light. The compounds have particularly good solubility and miscibility in solvent systems and in liquid polymers and prepolymers, which makes them useable in a wide range of polymeric materials.

Suitable polymeric materials include plastics materials for example polyethylene, polypropylene, ethylene/propylene copolymers, polyvinyl chloride, polyester, polyamide, polyurethane, polyacrylontrile, ABS, terpolymers of acrylates, styrene and acrylonitrile, styrene/acrylonitrile and styrene/butadiene. Other plastics materials such as polybutylene, polystyrene, chlorinated polyethylene, polycarbonate, polymethylmethacrylate, polyphenylene oxide, polypropylene oxide, polyacetals, phenol/formaldehyde resins and epoxy resins may also be used. Preferred plastics materials are polypropylene, polyethylene, ethylene/propylene copolymers and ABS.

Natural polymers for example natural rubber may also be stabilized, as may lubricating oils containing polymeric material.

The compounds of formula I may be incorporated by known methods into the polymeric material to be stabilized. Of particular importance is blending of the compounds with thermoplastic polymers in the melt, for example in a melt blender or during the formation of shaped articles, including foils, films, tubes, containers, bottles, fibres and foams by extrusion, injection moulding, blow moulding, spinning or wire coating.

It is not essential for the polymeric material to be fully polymerised before mixing with the compounds according to the invention. The compounds may be mixed with monomer, prepolymer or precondensate, and the polymerisation or condensation reaction carried out subsequently. This will of course be the preferred method of incorporation of the compounds into thermosetting polymers, which cannot be melt blended.

The compounds of formula I may be used alone or in combination with other stabilizers, for example hindered amine light stabilizers such as tetraalkylpiperidine light stabilizers and antioxidants.

Compounds of formula I with hindered amine light stabilizers may produce a synergistic effect in polyneric systems. Preferred hindered amine light stabilizers are those described in US Patent 4,408,051 and GB Patent 2,091,732 B, the contents of both patents (including their preferences) are incorporated herein by reference.

Examples of other stabilizers include sterically hindered phenols, sulphur or phosphorus-containing compounds or mixtures of these. More specific examples of these other stabilizers are benzofuran-2-ones; indolin-2-ones and sterically hindered phenols such as indolin-2-ones and sterically hindered phenols such as beta-(4-hydroxy3,5-ditert.-butylphenyl)-propionyl stearate, methane tetrakis (methylene-3(3',5'-ditert.-butyl-4-hydroxy-phenyl-)-propionate], 1,3,3-tris-(2-methyl-4-hydroxy-5-tert.-butyl phenyl)-butane, 1,3,5-tris(4-tert.-butyl-3-hydroxy-2,6-di-methylbenzyl)-1,3,5-triazin- 2,4,6 (1H, 3H, 5H)-trione, bis-(4-tert.-butyl-3-hydroxy-2,6-dimethylbenzyl)dithiolterephthalate, tris(3,5-ditert.-butyl-4-hydroxy- benzyl) isocyanurate, the triester of beta(4-hydroxy-3,5-ditert.- butyl-phenyl) propionic acid with l,3,4-tris-(2-hydroxyethyl)-5- triazin-2,4,6 (1H, 3H, 5H)-trione, bis [3,3-bis-(4'-hydroxy-3-tert.butyl-phenyl)-butyricacid] glycol ester, 1, 3,5-trimethyl-2,4,6- tris- (3,5-ditert. -butyl-4-hydroxy-benzyl) benzene, 2,2'-methylenebis-(4-methyl-6-tert.-butyl-phenyl) terephthalate, 4, 4-methylene- bis-(2,6-ditert.-butylphenol), 4,4'-butylidine--bis-(tert.-butyl- metacresol), 2,2' -methylene-bis-( 4methyl-6-tert -butyl-phenol).

Sulphur containing antioxidative co-stabilizers which may be used include for example distearylthiodipropionate, di-laurylthiodipropionate, methane tetrakis (methylene-3-hexylthiopropionate), methane tetrakis (methylene-3-dodecylthiopropionate)and dioctadecyldisulphide. Phosphorus-containing co-stabilizers include for example trinonylphenyl phosphite, 4,9-distearyl-3,5,8,l0-tetraoxadiphospha roundecane, tris-(2,4-ditert.butylphenyl)phosphite and tetrakis (2, 3-ditert.butylphenyl )-4 ,4 'biphenylene diphosphonite. Further additives such as aminoaryl compounds and U.V.-absorbers and light stabilizers e.g. 2- (2 '-hydroxyphenyl ) -benzotriazole, 2-hydroxybenzophenone, 1,3-bis-(2'-hydroxybenzoyl)benzene, sal icylates, cinnamates, benzoates and substituted benzoates, sterically hindered amines and oxalic acid diamides may be used. Other known types of additives, e.g. flame retardants and antistatic agents, may also be added.

The compounds of the invention can also be used in photopolymeric substrates containing photoinitiators for the photopolymer isation.

The compounds of formula I are especially suitable for use in organic polymer-containing coatings, particularly autanotive finishes.

Automotive finishes are generally solutions or dispersions of organic polymers or polymer precursors in organic solvents. The majority are stoving finishes, which require the application of heat, generally above 800C, in order to harden the finish in an acceptable time once it has been applied to the primer-coated metal surface. The hardening step may be accelerated by the use of an acid catalyst. The effect of this heating may be to accelerate the chemical reaction between polymer precursors in a thermosetting system, or to bring about fusion of particles of a thermoplastic polymer.

Many automotive finishes are metallic finishes, which contain flakes of metal, usually aluminium, in order to provide optical effects due to reflection. Such finishes are often two-coat finishes, in which a clear top coat finish is applied over a base coat finish containing a single pigment and/or metal flakes. The compounds of formula I can be in the top coat finish or the ground coat finish, preferably the former. Such two-coat metallic finishes have particular need of U.V.-stabilizers in the top coat, since the polymer in this coat is not protected by light-absorbing pigments, and it is subjected to almost double the normal amount of radiation because of reflection of light from the lower metallic layer.

The compounds of formula I are particularly useful in acid catalysed stoving finishes particularly in the top coats of two layer metallic finishes.

The compounds of formula I may be added to the finish at any stage in its manufacture, and may be added in solid form or in solution, preferably in the form of a liquid concentrate in a suitable solvent.

In practice the compounds of formula I are added as a solution in organic solvent to a liquid finish. In such finishes the binder material is between 35 % (low solid finishes) and 70 % by weight (high finishes); the binder material of the finish being in aqueous emulsion or suspension form (as an aqueous finish) and making up 20 to 30 % by weight of the finish. The compounds of formula I can also be added to powder finishes.

The compounds of formula I are to be added to the liquid or powder finishes before stoving or hardening. Preferably the compounds of formula I are used in liquid finishes since it is easy to add exact dosages. It is particularly preferred to use a concentrate (preferably in a hydrocarbon solvent) containing at least 40 % preferably 60 to 80 % by weight of the total weight of the concentrate of a compound of formula I to introduce the compound of formula I to finishes for stoving.

The addition of from 0.01 to 8 % by weight, preferably 0.2 to 4 % by weight of one or more compounds of formula I gives a clear improvement in the light- and weather-stability of organic pigments in stoving finishes as well as reducing the tendency to hairline cracking and loss of gloss as the result of weathering. This is also found for metallic finishes and excellent long-term stability of the clear top coat of two layer metallic finishes is obtained. In such finishes, the compound of formula I may be added to the metallic undercoat, the clear top coat or both, preferably only to the clear top coat. The metal surface to be finished may be under-coated with primer coatings as is customary in the art of coating metal surfaces. The invention will now be illustrated by the following Examples.

Example 1 10.4 g of the compound of formula lb

are warmed with 4.3 g of 2-ethyl - 1 - hexanol (isooctanol) and 2.4 g of pyridine in 50 mls of toluene for 7 hours at 900C. The white suspension is added to water, the toluene phase is separated off and then washed with water twice. The mixture is then concentrated and white residue is recrystallised from alcohol. The resulting product is of formula la

and is a white powder having a melting point of 73 - 750 C.

Example 2 A mixture of 30 mls of ethylene glycol and 5.0 g of triethylamine is prepared and this is reacted with a suspension of 10.4 g of the compound of formula lb (defined in Example 1) in 20 ml of tetrahydrofurane. A white product precipitates out. After one hour the mixture is diluted at 600 C with methanol and then the product is filtered off, after which the product is washed with water.

After recrystallising from ethanol, the resulting product is of formula 2a

and is a white powder having a melting point of 189 - 1900 C Examples 3 to 5 The following compounds can be prepared by a method analogous to that of Example 1 or 2 from appropriate reactants.

Example 3

Example 4

Example 5

Example 6 Preparation of the compound of formula 6a

22.3 g of the compound of formula 6b

10.9 g of peaminophenol and 0.5 g of boric acid are placed in 30 ml of ethylene glycol at 1100C. The resulting alcohol is distilled off on a rotary evaporator. After cooling to about 800C, 50 ml of methanol are added and then the mixture is cooled to roan temperature. The resulting precipitate is then separated from the liquid phase by vacuuming off the latter.

The precipitate is then washed with water.

A grey-white product of formula 6a results having a melting point of 194-1960C.

Example 7 Preparation of the compound of formula 7a

23.7 g of the compound of formula 7b

10.9 g of paminophenol and 0.5 g of boric acid are added to 30 ml of ethylene glycol at 1100C.

The resulting alcohol is distilled off on a rotary evaporator.

After cooling to 800C, 50 ml of ethanol are added and then the mixture is cooled to room temperature.

The resultant precipitate is separated from the liquid phase by vacuuming off the latter. The precipitate is washed with water.

A white product of formula 7a results having a melting point of 190-1940C.

Example 8 A compound of formula 8a

can be prepared from the appropriate acid chloride by the addition of water.

APPLICATION EXAMPLE A A clear finish of 80 Parts of Viacryl SC 344 (a 50 8 solution of an acryl resin from Vianova), 13.9 Parts of Maprenal MF 80 (a 72 % solution of a melamine resin from Hoechst) and 4.1 Parts of Byketol OK (from Byk-Malinckrodt) is added to 2 parts of a compound of formula la (described in Example 1). After 1 minute the light stabiliser material so formed is dissolved in a finish. The finish is applied conventionally (according to the known 2 layer procedure) to a metallic or single pigment finish whilst still wet by spraying to form a layer having a thickness of 30 to 40 um. The resulting coating is then hardened at 1400 for 30 minutes. The coating shows very good resistance to U.V.

light and weathering.

APPLICATION EXAMPLE B A clear finish of 29.5 Parts of Setalux C-1502 XX-60 (a 60 % solution of an acryl resin from Synthese By.), 39.2 Parts of Setalux C-1382 BX-45 (a 45 % solution of an acryl resin from Synthese Buy.), 21.4 Parts of Setamine US-138 BB-70 (a 70 % solution of a melamine resin from Synthese By.), 2.5 Parts of Baysilonoil [(2 % solution in Xylene) from Bayer] and 7.4 Parts of Depanol Y (a solvent from Hoechst) is stirred together with 2.5 parts of a compound of formula la (described in Example 1) and 2 parts of an acid catalyst derived from phosphoric acid (Type: Catalyst 269-9 from American Cyanamid) to form a homogeneous mixture.The finish is applied conventionally (according to known 2 layer procedure) to a metallic or single pigment finish whilst both are still wet by spraying to form a layer having a thickness of 30 to 40 um. The resulting coating is then hardened at 1100 for 20 minutes. The coating shows very good resistance to U.V. light and weathering.

APPLICATICN EXAMPLE C A clear finish of 75 Parts Macrynal SH 510 N (a hydroxy containing acryl resin from Bayer) 2 Parts of Baysilon-oil A [(1 % solution in xylene) from Bayer] 0.3 Parts of dibutyl zinc dilaurate 0.35 Parts diethanolamine 5.0 Parts of ethylglycol acetate 5.0 Parts of Solvesso 100 6.0 Parts of Xylene and 6.36 Parts of butyl acetate is added to 2.5 parts of a compound of formula la (described in Example 1) and 30 parts of Desmodur N 75 (from Bayer). The homogeneous mixture so formed is applied conventionally (according to the known 2 layer procedure) to a metallic or single pigment finish whilst both are still wet by spraying to form a layer having a thickness of 30 to 40 urn and the resulting coating is hardened over 20 minutes at 80 to 900.The resulting 2K-PUR coating shows a good resistance to U.V. light and weathering.

APPLICATION EXAMPLE D A single white pigmented finish of 14.30 Parts of Setamine US-132 BB70 (a 70 % solution of a melamine resin from Synthese) 57.15 Parts of Setal 84 W-70 0 (a 70 % solution of an alkyd resin from Synthese) 7.70 Parts of n-butanol 1.85 Parts of butylglycol acetate 9.50 parts of Xylene and 25 Parts of titanium dioxide (Rutil type) is added with 1.38 parts of the product of formula la (see Example 1). The finish is conventionally applied to a grounded steel metal to which a filler of layer thickness 20 to 30 um has been annealed, by spraying and after standing for 30 minutes at room temperature the steel metal surface is annealed at 1200C for30 minutes. The resulting coating shows very good resistance to U.V. light and weathering.

In Application Examples A to D instead of the product of formula la, an appropriate amount of the product of any one of Examples 2 to; may be used.

Claims

CLAIMS:

1. A compound of formula I

in which each R1, independently is selected from hydrogen, C1-12alkyl, C1-12alkoxy and halogen; R2 has a significance of R1, independently of R1, or R2 is OH, R20 is -CO-OR6 or, when each R1 is hydrogen and R2 is 2-C1-4alkoxy, R20 is additionally -OH; R3 is hydrogen or methyl; and R6 is hydrogen; unsubstituted C6~22alkyl, uninterrupted or interrupted by 1 or 2 oxygen atoms or C1-22alkyl mono- or di-substituted by OH and uninterrupted or interrupted by 1 or 2 oxygen atoms; provided when each R1 and R2 is hydrogen, then R6 is not hydrogen.

2. A compound according to Claim 1, in which R1 is R1' where R1' is hydrogen, C14alkyl--, C14alkoxy or chlorine.

3. A compound according to Claim 1 or Claim 2, in which R2 is R2' where R2' is hydrogen or C1-2alkoxy.

4. A compound according to any one of the preceding claims in which R6 is R6' where R6' is unsubstituted C6-18alkyl, uninterrupted or interrupted by one -O- group or C1-18alkyl monosubstituted by -OH and uninterrupted or interrupted by one or two -O- groups.

5. A compound according to Claim 4, in which R6 is R6 where R6" is unsubstituted C6,18alkyl or Cl,galkyl monosubstituted by -OH and uninterrupted or interrupted by one or two -O- groups.

6. A compound of formula V

in which R3 is hydrogen or methyl; R10 is hydrogen, methyl or ethyl; and R11 is -OH or -COOH.

7. A compound according to Claim 6, in which R3 is hydrogen and R11 is -OH.

8. A process for preparing a compound of formula I according to Claim 1 where R20 is -CO-OR6 comprising reacting a compound of formula II

with a compound of formula III HO-R6 (III) where the symbols are as defined in Claim 1; at an elevated temperature.

9. A process for preparing a compound of formula I according to Claim 1 where R20 is -OH comprising reacting a compound of formula VI

with a compound of formula VII

at an elevated temperature.

10. A process for stabilising a polymeric substrate comprising adding a light stabilising amount of a compound of formula I as defined in any one of Claims 1 to 5 or a compound of formula V defined in Claim 6 or Claim 7 to the substrate.

11. A polymeric material to which a compound of formula I defined in any one of Claims 1 to 5 or a compound of formula V as defined in Claim 6 or 7, has been added.

12. A lacquer composition based on acrylic, alkyd or polyester resins containing a compound of formula I defined in Claim 1 or a compound as defined in Claim 6 or 7.

13. A compound of formula I defined in Claim 1 substantially as herein described with reference to any one of Examples 1 to 7.

14. A polymeric composition substantially as herein described with reference to any one of Application Examples 1 to 4.

15. A process for stabilising a polymeric material substantially as herein described with reference to any one of Application Examples A to D.

16. A process for stabilising a polymeric material comprising applying to the polymer material a light stabilising amount of a compound substantially as herein described with reference to any one of Examples 1 to 7.