GB2031006A - Isoindoline Derivatives and Their Use - Google Patents

Abstract

New isoindoline derivatives of the formula <IMAGE> where R<1> and R<2> are methyl or ethyl and are identical or different give deep red colorations in thermoplastics, which are very heat-stable. The N,N'- dimethyl compound (I), for example, is stable in linear polyesters at up to 300 DEG C.

Description

SPECIFICATION - Isoindoline Derivatives and Their Use The present invention relates to novel isoindoline derivatives and to their use for masscoloring of thermo-plastics.

The novel isoindoline derivatives have the formula

where R1 and R2 are methyl or ethyl and may be identical or different.

In plastics, e.g. polystyrene, polyacrylonitrile, polyacrylate, polymethacrylate, polycarbonate, styrene/acrylonitrile/acrylate copolymers, styrene/butadiene/acrylonitrile copolymers, styrene/acrylonitrile copolymers and styrene/butadiene copolymers, the compounds of the formula(l) give deep red colorations which are very heat-stable. For example, compounds (I) are stable in polystyrene at up to 3000C. By way of comparison, the most closely related known compound, described in Example 2 of German Laid-Open Application DOS 2,615,394 and obtained by condensing 1 -amino-3-iminoisoindolenine with 2 moles of 2-cyanomethylbenzimidazole is only stable at up to 2200 C. This behavior of compounds (I) was surprising and unforeseeable.

The compound of the formula I where R1=R2=-CH3 is stable at up to 3000C in polymers composed of styrene, acrylonitrile and acrylates or styrene and butadiene, and in linear polyesters.

In polymethacrylates, the compound is stable at up to 2800C.

A compound (I) can be prepared by condensing a 1,3-disubstituted isoindolenine, e.g. a 1-amino3imino or 1 -amino-3,3-bis-alkoxy-isoindolenine, with 2 molar proportions of the appropriate 1alkyl-2-cyanomethylbenz-imidazole(s), in the conventional manner.

The condensation is carried out in an organic medium. Examples of suitable media are alkanols, advantageously used in the presence of aliphatic C2-C4-carboxylic acids, or polar waterimmiscible solvents, e.g. nitro-benzene.

The condensation is as a rule complete in from 2 to 5 hours at from 80 to 1 200C. The condensation product may be isolated from the reaction mixture in the conventional manner.

The compound (I) is obtained directly in a pure form, in which it may be used for coloring plastics of the stated type.

The Examples, and Use Examples, which follow illustrate the invention. Parts and percentages in the Examples and Use Examples are by weight.

Example 1 2 parts of a 1 -amino-3-imino-isoindolenine glycol adduct (obtained by reacting ophthalodinitrile with ammonia in ethylene glycol) and 5 parts of 1 -methyl-2-(cyanomethyl)- benzimidazole in 120 parts of methanol and 20 parts of glacial acetic acid are stirred under reflux for 4 hours. When the mixture has cooled, it is filtered and the filter residue is washed with methanol and water, and is dried.

Yield: 1.66 parts of the compound of the formula I, where R1=R2=-CH in the form of red needles.

Example 2 7.8 parts of the compound

and 5.5 parts of 1-ethyl-2-(cyanomethyl)- benzimidazole are introduced into 95 parts of methanol and 20 parts of glacial acetic acid and the mixture is stirred under reflux for 2 hours.

When it has cooled, the condensation product is filtered off, washed with methanol and dried.

Yield: 4.6 parts of the compound of the formula I, where R1=-CH3 and R2=-C2H6,in the form of bright red needles.

Example 3 414 parts of a 1 -amino-3-imino-isoindolenine glycol adduct (cf. Example 1) and 8.55 parts of 1 methyl-2-(cyanomethyl)-benzimidazole in 120 parts of nitro-benzene are stirred for 3 hours at 1 0O0C. When the mixture has cooled, the condensation product is filtered off, washed with methanol, acetic acid and again with methanol, and dried.

Yield: 7.6 parts of the compound of the formula I, where R1=R2=-CH3, in the form of red needles. The compound has the same properties as those of the compound obtained in Example 1.

Example 4 5.9 parts of the 1 -amino-3-imino-isoindolenine glycol adduct and 12.95 parts of 1 -ethyl-2 (cyanomethyl)-benzimidazole in 120 parts of nitrobenzene are stirred for 3 hours at 1000C.

When the mixture has cooled, it is filtered and the filter residue is washed with methanol, with acetic; acid and again with methanol and is dried.

Yield: 8.9 parts of the compound of the formula 1, where R1=R2= C2H 5, in the form of bright red needles.

Use Examples a) 0.05% strength, transparent coloration of polystyrene.

0.05 part of the dye from Example 1 is mixed with 100 parts of milled polystyrene polymer in a drum mixer. The mixture is fused, and homogenized, in an extruder at a barrel temperature of from 200 to 25O0C. The colored material is granulated by face-cutting. Moldings are then produced from the granules on an injection molding machine at from 200 to 3000C.

The moldings are bright red, fluoresce in a similar hue, and exhibit excellent lightfastness.

No differences in hue are observed at processing temperatures from 200 to 3000C.

b) 0.05% strength transparent coloration of a styrene-budadiene copolymer.

The procedure described for a) is followed, but instead of polystyrene a styrene-butadiene copolymer is used.

The bright red injection moldings obtained are lightfast. The dye is stable at processing temperatures of up to 3000.

c) 0.05% strength transparent coloration of a styrene/acrylonitrile/acrylate copolymer.

The procedure described for a) is followed, but using a styrene/acrylonitrile/acrylate copolymer.

Bright red colorations are obtained. The dye is stable in this copolymer at up to 3000C.

d) 0.05% strength transparent coloration of polymethyl methacrylate.

The procedure described for a) is followed, but using a polymethyl methacrylate as the polymer.

Fluorescent lightfast bright red colorations are obtained. The dye is stable in this medium at up to 28O0C.

e) 0.05% strength transparent coloration of a styrene/acrylonitrile copolymer.

The procedure described for a) is followed, but using a copolymer comprising 35% of acrylonitrile units and 65% of styrene units. Fluorescent bright red injection moldings are obtained. The dye is stable in the copolymer at up to 3O00C.

ft 0.05% strength transparent coloration of a styrene/acrylonitrile/butadiene copolymer.

The- procedure described for a) is followed, but using a graft polymer based on styrene, acrylonitrile and rubber. Bright red injection moldings are obtained. The dye is stable in the copolymer at up to 3000C.

Claims (6)

Claims

1. An isoindoline derivative of the formula

where R1 and R2 are methyl or ethyl and are identical or different.

2. The isoindoline derivative claimed in claim 1 in which R' and R2 are both methyl.

3. An isoindoline derivative claimed in claim 1 when prepared by condensing a 1,3-disubstituted isoindolenine with 2 molar proportions of the appropriate 1-alkyl-2- cyanomethylbenzimidazole(s) in an organic medium at from 80 to 1200C.

4. A process for melt-coloring polystyrene, polyacrylonitrile, polyacrylate, polymethacrylate, polycarbonate, styrene/acrylonitrile/acrylate copolymers, styrene/butadiene/acrylonitrile copolymers, styrene/acrylonitrile copolymers and styrene/butadiene copolymers, wherein a compound as claimed in any of claims 1 to 3 is used as the dye.

5. Synthetic thermoplastics material colored with a compound as claimed in any of claims 1 to 3.

6. A process as claimed in claim 4 carried out substantially as described in any of the foregoing Use Examples a) to f).