NZ221070A - Heat-curable organosol sterilisation-resistant coatings - Google Patents

Abstract

1. Heat-curable organosol for forming firmly adhering, pore-free and sterilization-resistant coatings, containing a vinyl chloride homopolymer, a phenolic resin, a polyester, a diluent, a catalyst and, if appropriate, conventional additives, characterized in that it contains a) 20 to 50 % by weight of the vinyl chloride homopolymer, b) 1 to 15 % by weight of the phenolic resin, c) 1 to 15 % by weight of an epoxide resin, d) 4 to 20 % by weight of a linear polyester based on aromatic and/or cyclic dicarboxylic acids and e) 25 to 60 % by weight of the diluent.

Description

New Zealand Paient Spedficaiion for Paient Number £21 070 22107 . ; rvi. £,jwcifi';ai;on Fi.'sd: /t.'.f.f.f .Q?/4y,6&- ' "" . '2 6 APR'{920 l . o ai ^ v*v' "i-' -«■ -v **i •Al ■ «>->" f'* NEW ZEALAND PATENTS ACT, 1953 No.: Date^ COMPLETE SPECIFICATION ^ Heat-curable organosol and its use 'i, 14 JUL 1987*, ' .c f ywe, ICI LACKE FARBEN GmbH, Dusseldorfer Strasse 102, i j D-4010 Hilden, Federal Republic of Germany hereby declare the invention, for which Ix/ we pray that a patent may be granted to me/us, and the method by which it is to be performed, to be particularly described in and by the following statement: - I /. 22107C *« i D Description Tne invention relates to a neat-curable organosol for forming firmly adhering, p ore-free and s ter i I i za:i on-resistant coatings of, in particular, metals in accordance with the preamble of the main claim and its use for the internal coating of foodstuff containers.

. Tin plate, black plate and aluminium plate for packages are in most cases provided with a coating, wnich nas the object of reducing or eliminating contact between tne contents and the packaging material. On tne one nanc, tne packaging should not adversely affect the contents ana, on the otner hand, corrosion effects on the packaging material due to the contents should be avoided. Such coatings are applied before the production of the packages, 15 such as cans and containers, in small layer thicknesses by tne roller-coating process. Thin coatings can be porous and also prone to damage by scratching during the production of the cans and containers. On the other hand, thicker coatings have the disadvantage of poorer deformaoility and 20 frequently lead to cracks in the coating at oeads and in ~ embossed areas.

It is known to produce coatings of low porosity on the basis of polyvinyl chloride, for example in the coating of beverage cans. However, only solutions of Low ' j ^ 2 5 solids content can be prepared from polyvinyl chloride or vinyl chloride copolymers/ because a certain processing viscosity must not be exceeded. Only films of low thickness can be produced with these coatings of low concentration.

On the other hand, it is known to use plastisols and organosols based on vinyl resins for the coating of crown caps. Such organosols represent dispersions of finely divided, solid plastics in liquid plasticizers and organic diluent systems. The solids content of olasti-35 sols and organosols is high and is between 60 and 1002.

When using known plastisols and organosols, however, coatings of low adhesion and water resistance, particularly during boiling and sterilizing, are obtained. The field of use of these coatings is therefore extremely restricted. application takes the place of the elastic sealing disc, which was usual earlier, for gas-tight and liquid-tight sealing of the bottle mouth. Consequently, the plasti-sol application is restricted to the region of. the bottle mouth or the plane sealing face. In spite of excellent sealing ability, however, the plastisols show extremely low adhesion, so that, without additional measures, they are unsuitable as sealing means, because they can readily be peeled off as a coherent film from the smooth sealing face. In order to counter this, it is known to use an organosol as an adhesive primer. However, this organosol is covered by the plastisol functioning as the seal and consequently does not come into contact with the bottle neck. British Pa ten z Specification 1,105,620 has also disclosed special polyesters, obtained from dihydric alcohols and dicarboxylic acids, as plastic izers for polyvinyl chloride resins. The extent to which polyvinyl chloride plasticized with such polyesters can or may additionally contain other resins is not known. on tin, steel and aluminium sheet, wherein an organosol coating composition with a vinyl chloride homopolymer, a polyester plasticizer and a further resin is aoplied. This represents a decorative coating with, for example, a textured, corrugated, leather-like or embossed appearance. With respect to its resistance, the coating therefore needs to withstand only the usual exposure from the chloride homooolymer, a phenolic resin, an aminoplast resin, a polyester, a diluent, a catalyst, a polymeric plasticizer and, if appropriate, conventional additives,1* for producing a firmly adhering, pore-free and sterilization-resistant internal coating on foodstuffs containers In the case of the crown caps, the plastisol U.S. Patent Specification 3,137,666 describes a process for the production of firmly adhering coatings outside X&js—us a ..nj^7a n organosol which contains a vinyl 22107C ^ - U - of tin-plated, untreated or surface-treated black plate, .AM aluminium or aluminium alloys ^i-s—k n ow-n—f-r o m—G e r m o n—Patent—- •j c i f i c d L i 'UTi—2-76-2-9 ,-62 9-w to the polymeric p I a s t i - ^ cizer whicn is necessary for obtaining the required flexi-5 bility of tne film and which must necessarily have a low molecular weight, problems arise since this plasticizer can migrate out of the film during baking, steri lira; ion and storage and accumulate in the foodstuff present in the package. Tne coatings obtain aols according to the 10 teaching of this state of the art therefore require improvement.

There is also 3 desire yet further to imorove the organosols used with respect to their adhesive strength v on the metallic substrate, in particular during stamping and/or cutting of coated metal sheets, and with respect to their resistance to aggressive contents. Furthermore, there is a demand for further increasing the flexibility, the pore tightness and the mechanical resistance of the coating films formed with the aid of the heat-curable 20 organosols, so that the sheets coated with them can also be employed in all recent processing and deformation methods in the packaging industry (deep-drawing, bead-pressing, flanging, notching and welding etc.) and can thus oe used in new ways with technically progressive a s -25 pects. For reasons of protecting tne environment, it is also desirable to reduce the formation of internal coatings of foodstuffs containers with the use of volatile organic diluents and/or solvents.

It is therefore the object of the present inven-30 tion to improve a heat-curable organosol of the generic type described at the outset, in such a way that an increase in the adhesive strength of the coating films formed with them on the metallic substrate, increased resistance to the contents during the sterilization process 35 and during storage,"a substantial increase in flexibility and pore tightness and in particular mechanical strength during deformation of the sheets, even without the use of a low-molecular plasticizer, is obtained.

This object is achieved by the characterizing features of the heat-curaole organosol according to tne main claim.

The subclaims relate to particularly preferred em-5 bodiments of this subject of the invention and to the use of this heat-curable organosol for producing a firmly * adhering, pore-free and 3ter iIi : at ion-res is tant internal coating on foodstuffs containers of tin-plated, untreated or surface-treated black plate, aluminium or aiuminium 10 alloys. f*) Surprisingly, it has now been found that, witn tne organosol according to the invention, transparent, well-levelling and pore-free coatings can be produced which, with very high flexibility, show an unexpectedly 15 high degree of sterilisation resistance and resistance to the contents. ?urthermor9, it was not to be expected that protective coating films of this corrosion resistance would also oe outstandingly suitable as an adhesive coating for PVC seals for glass closures and other clos-2 0 ures of any type.

Particularly unexpected, however, is the fact that, with the organosol according to the invention, an unplas-ticized organosol based on polyvinyl chloride can be produced for tne first time, with which it was possible to replace the hitherto conventional polyvinyl chloride plas-ticizers or ,*£=£■*' low-molecular polymeric polyester plasticizer s j y e d—according—t-a—German—Patent—SpoTifieatijn— -2<iQ3 9>629- by a h i gh-mo I e c u L a r polyester resin which, in conjunction with the other resin constituents of the organosol, nas a particularly high compatibility with polyvinyl chloride, so that homogeneous and stable coating films having the properties particularly desired for a protective coating can be obtained.

The firmly adhering coatings formed with the aid 35 of the heat-curable organosol according to the invention are not only resistant to sterilization and foodstuffs but, to a surprisingly great extent, withstand extremely extensive deformations when a tear-open line or notch • I / —*s 221070 Line is applied, and show a substantial increase in pore tightness. ConsequentL/, these heat-curable organosoLs are especiaLL/ suitable for the internal coating of foodstuff containers such as, for example, preserve cans, 5 which have a rivet and, in the top or body, a notch line, - along which the package can be torn open. Due to the extensive cold-forming of the sheet metal, such rivets and notch lines are particularly at risk from corrosion.

Tne heat-curable organosol according to the in-,—^ 10 vent ion contains, as the vinyl chloride homopoLymer pre- sent in a dispersed form, preferably a fine-grain, neutral homopolymer having a K value (according to H. Fikentscher » corresponding to DIN 53,726) of 63 to 90, preferably 70 to 30, and a viscosity number (likewise according to DIN 15 53,726) between 115 and 230. fine-grain, neutral, emulsi-fier-free vinyl chloride homopolymers which can be converted into pastes and have a particularly low viscosity and particularly high storage stability and which impart high clarity to unpigmented coating films are particu-20 larly preferred.

In addition to the vinyl chloride homopolymer, the organosol according to the invention contains, as essential constituents, 5 to 15% by weight of a phenolic resin, 1 to 15% by weight of an epoxide resin and 4 to ^ ^ 25 20% by weight of a linear polyester based on aromatic and/or cyclic dicarboxylic acids. Phenolic resins which are particularly well suitable according to the invention are heat-curable, unplasticized phenol/formaldehyde .r-~ resol resins which are highly compatible with epoxide ^ 30 resins and vinyl chloride homooolymers, and in particular etherified cresoI/forma Idehyde resins.

As the epoxide resin, the organosol according to the invention preferably contains an epoxide resin having a number average molecular weight of 300 to 900 and a 35 corresponding epoxide equivalent weight of 150 to 500.

Reaction products of epichlorohydrin and bisphe-nol A, such as are described, for example, in "Handbook of Epoxy Resins", edited by H. Lee and K. Neville, McGraw-Hill Book Compan/, New York (1967), are particularly preferred.

The linear polyester used accord i n g jt o the invention and based on aromatic ana/or cyclic dicarboxylic acids is preferaoly a linear saturated copolyester containing nydroxyl groups and based on phthalic acid, iso-pnthalic acid, terepnthalic acid, cyclohexanedicarbcxylic acid, nexanyarophtha Iic acid, nexahydroisoohcha Iic acid and/'or hexanyoroterephthalic acid and alipnatic and/or cyclic diols, or based on p-hydroxybenzoic acid. As tne aliphatic and/or cyclic diol, this polyester preferably contains 1 , 2-p <- ooy i ene glycol, 1 , 3-p ropy I e ne glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butyLene glycol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-2-mechyl-1,3-proaanediol , 1,6-hexamethyIene glycol, 1,2—b is — (nydroxymetnyl)-cyclonexane, 1,5-bis-(hydroxymetnyl) -cyclonexane, 1,4-bis-(hydroxymetnyl)-cyclohex3ne, b i s -(nydroxymetnyl)-tricyclodecane, 4,4'-dihydroxydiohenyl ether and/or 4 '-dihydroxydioh enyI .

This polyester has a molecular weight of from 10,000 to 24,000, preferably from 14,000 to 22,000, and a glass transition point, determined by differential thermal analysis, in the range from 60 to 80°C and preferably about 70°C .

The molecular weight of tne Linear polyesters employed according to the invention is thus markedly higher fbitliarlo than that of the polyesters/whioft ain used as polymeric plastic izers according—£-o—t-h-e—t-aa-ehing of -German Patent— * -S p-o c -i f i c J t i o n—27 029,639-: The molecular weight of these polymeric plasticizers is as a rule below 8000, but is in general between 400 and 4000. It is precisely in view of this markedly higher molecular weight of the linear polyesters employed according to the invention that the stability of the organosols and the flexibility of the coatings obtained with them are surprising.

As a diluent and/or solvent, the organosol according to the invention contains an aromatic hydrocarbon, if appropriate as a mixture with terpene hydrocarbons, alcohols and/or ketones. The solvents or diluents are here p r e f e r -ably matched to one another in such a way that undue swell ing of the vinyl chloride polymer is avoided.

To accelerate the poLycondensation of the resins used and to improve adhesion to the substrate, an acid catalyst is preferably used. Suitable catalysts are especially formic acid, acetic acid. Lactic acid, tartaric acid, citric acid, salicylic acid, phthalic acid, phosphoric acid and its esters, a-toluenesulphonic acid, dodecylbenzenesulphonic acid, dinonylnaphthalenedisul-phonic acid, esters of titanic acid such as butyl :i tan-ate or isopropyl titanate, and also cnelates such as titanium acetyLacetonate .

In addition to the abovementioned essential constituents, the organosols of the invention can also contain conventional additives such as slip agents, stabilizers, dyes, fillers, pigments such as, for example, tica-n ium dioxide or aluminium flake pigments, ana ocner coating auxiliaries.

According to a further embodiment according to the invention, the heat-curable organosol contains, as an additional constituent, 0.1 to 10% by weight of an amino-plast resin, in particular a triarine resin and/or a benzog'uanamine resin. 3y means of this addition, a surprising further increase in the adhesion of the coating formed on metallic substrates is achieved, with a simultaneous increase in the hardness of tne coating film.

According to a further preferred embodiment of the invention, the heat-curable organosol additionally contains 0.5 to 10% by weight of a vinyl chloride copolymer in the form of a solution. An increase in the adhesion of the interlayer, in the case of the formation of two-coat systems on metallic substrates, can be achieved in this way. The vinyl chloride copolymers used in this embodiment of the invention are preferably vinyl chloride/ vinyl acetate/maleic acid copolymers or vinyl chloride/ vinyl acetate/vinyl alcohol copolymers which are added in the form of a solution to the finished organosol I n 22107C ronraining the other constituents. A copolymer of 31% by weight of vinyl chloride, 17% by weight of vinyl acetate and 2X by weight of maleic acid (VinyLite VMCA from Union Carbide Corooration) is oarticularly preferred. 5 Due to their special composition, the heat-curable organosols according to the invention are especially suitable for producing pore-free coatings on black plate, such as the materials usual in the black plate packaging industry, namely tin-plated, untreated and surface-treated black 10 ciate, aluminium and aluminium alloys. Since the coating produced with the aid of the organosol according to the invention is resistant to boiling, cans and containers for foodstuffs, in particular preserve cans and lids, can advantageously be coated. For this purpose, the coating com-15 positions can be used either in one layer or in several layers or as a primer or topcoat in comoination with a coating of a different composition, preferably a coating oased on an epoxide resin, for tne production of internal coatings on fooastuff containers. The invention therefore 20 relates also to the use of the organosol, according to Claim 14.

The organosols according to the invention are applied especially in layer thicknesses of 7 to 30 g (dry weight) per square metre to the metal sheets, but thinner v./ 25 coatings are also possible. The devices and drying ovens normally used for panel coating can be employed here. Tne drying time is preferably 8 to 15 minutes at drying temperatures of 170 to 225°C. The organosol according to the invention can also be applied by means of other 30 metnoas, such as casting or spraying, or by means of a coil-coating method. As already indicated, the coatings can be used as primers or can subsequently be provided with a further coating layer.

The coatings produced with the heat-curable orga-35 nosols according to the invention withstand sterilization' in various test solutions, such as water, 3% sodium chloride solution, 3% acetic acid solution, ZX tartaric acid solution and 1 % .lactic acid solution, without water I . - 10 - aosorption ana without Loss of adhesion.

It is to be regarded as a speciaL advantage of the coatings oroduced with tne aid of the organosols according to the invention that they show a very Low p o -5 rosity and a very high resistance to mechanical stresses. Such stresses occur in particular during the provision of notch Lines and rivets, which allow convenient opening of tne can py hand. Almost all hitherto known internal coatings are damaged in tnese treatments, so tnat prsfe-10 rential corrosion occurs at these points, and this is ) either accepted or orevented by rurtner coating. Due to the special composition of the heat-curable organosols according to the invention, coatings are thus obtained wnich are particularly corrosion-resistant, steriLization-15 resistant and mechanically stable and are therefore suitable to an outstanding degree for the internal coating of black plate packaging materials with tear-oosn Lias of, in particular, aluminium, aluminium alloys or black steeL pLate.

The examples which follow and the comparison ex ample serve to illustrate the invention further. £xamples In the examples which follow, the raw materials indicated below are used: Vinyl chloride homopolymer Commercially available pulverulent vinyl chloride homopolymer having a K value of 70; Vinyl chloride copolymer Solution of a commercially available vinyl 30 chloride copolymer based on VC / VAc/ma Ieic acid in a ketone/soIvent mixture. The quantity data relate to the solids contents of the vinyl chloride copolymer; Phenolic resin Commercially available, butanolized, unplasti- cized cresoI/formaLdehyde resol resin solution in alcohol- The quantity data relate to the solids contents of the phenolic resin solution; I / /?v A (J \ ASS v ' - 11 - Epoxide rgsin Commercially a v a i I a o I e liquid epoxide resin having an epoxide equivalent weight of 190; Polyester resin ~v Commercially available linear, saturated poly ester resin having a glass transition point of 70°C ; Aminoolast resin 10 Commercially available solution of benzoguan- --—v . j amine resin in alcohol. The quantity data relate to the solids contents of the amino-plast resin solution; "XJ Catalyst A 50% solution of phosphoric acid (35%) in alcohol ; Catalyst B % solution of a commercially available sulpho-nic acid in alcohol; Catalyst C % solution of butyl titanate polymer in butyl-glycol; Catalyst P 75% solution of a commercially available titanium -—^ chelate in alcohol; Slip agent 45% dispersion of a synthetic wax in an aromatic hydrocarbon mixture as a diluent; Aluminium flake pigment 30 Commercially available aluminium paste consisting of 65 parts by weight of a finely disperse aluminium flake pigment and 35 parts by weight of a hydrocarbon mixture; Diluent mixture 35 Mixture of the following components: Aromatic hydrocarbons 83.40% by weight Alcohols 8.30% by weight Ketones 2.80% by weight Glycol esters 5.50" by weight 100.00% by weignt Example 1 An organosol of the following composition is pre pared by mixing the indicated constituents: t Vinyl chloride homopolymer .00% by we i g n t Phenolic resin 4 .00% by weignt Epoxide resin 3 .00% by weight Polyester resin >8 o o • by weight Catalyst A 0 .20% by weight Catalyst C 0 $ o 3* by weight SI id agent 0 .50% by weight Diluent mixture 42 .20% by w e i a h t 100 .00% by weight Example 2 An organosol of the following composition is prepared by mixing the indicated constituents: O Vinyl chloride homopolymer 31 .50% by weight Phenolic resin 6 .50% by weignt Epox i de resin 7 .20% by weight Polyester resin 9 • o o a* by weignt Aminoplast res in 2 .70% by weignt Catalyst A 0 .20% by we i gn t Catalyst B 0 . 10% by weignt Catalyst C 0 . 10% by we i g h t Catalyst D 0 .20% by we i gh t Slip agent 0 .50% by we i g n t Diluent mixture 42 .00% by we i ah t 100, .00% by we i gh t rr;'l 30 Example 3 An organosol of the following composition is prepared by mixing the indicated constituents: Vinyl chloride homopolymer 30.00% by weight Vinyl chloride copolymer 3.00% by weight Phenolic resin 3.50% by weight Epoxide resin 7.00%byweight Polyester resin 8.70%byweight Catalyst A 0.20% by weight V .

Catalyst C Slip agent Diluent mixture ^ Z j 0.10% by weight 0.50% by weight 47.00% by weight 100.00% by weight Example 4 An organosol of tne following composition is pre-□ared by mixing the indicated constituents: Vinyl chloride homopolymer 3 1.00% by w e x: rn Vinyl chloride copolymer 1.50% by w e gnt PhenoLic resin .00% by we g n t Epoxide resin 7.00% by w e gh t Polyester resin 9.00% by w e gnt Aminoplast resin 1.50% by we ght Catalyst A 0.20% by w e gh t Catalyst B 0.05% by w e ght Catalyst C 0.10% by w e ght Catalyst 0 0.10% by we ght Slip agent 0.50% by w e ght Diluent mixture 44.05% by we ght 100.00% by we i ght Example 5 An organosol of the following composition is ore-pared by mixing the indicated constituents: Vinyl chloride homopolymer 29.00% by we ght Phenolic resin 6.00% by we ght Epoxide resin 6.50% by we ght Polyester resin 8.50% by we ght Aminoplast resin 2.50% by we ght Catalyst A 0.20% by we ght Catalyst B 0.10% by we ght Catalyst C 0.10% by we ght Catalyst D 0.10% by we ght Slip agent 0.50% by we ght Aluminium flake pigment .00% by we ght Diluent mixture 41.50% by we ght 100.00% by we i ght Comparison example As a comparison example, the example from German Patent Specification 2,029, 629 may be used, which d e- scribes an organosol of tne following composition : Vinyl chloride honiODOlyirer 45.00% by we ght Polyester plasticiz e r (ad i p i c acid polyester having an average o molecular weight of 1 100) 9.00% by we ght phenolic resin 3 .00% by we ght Aminoplast resin 3.00% by we ght Acid catalyst 0.10*. by we gnt •Q Heat stabilizer 2.00% by w e gnt Diluent mixture 27.90% by w e ght 100.00%. by we i ght •* % ; -y o - "V Substrates of the following types: Substrate I: t inplate, passivation 311 ("Andralyt")(*) Substrate II: E.C.C.S. (electrolytic chromium-coated steel) ("Ancrolyt")(*) (*) The descriptions "Andralyt" and "Ancrolyt" are trademarks of Rasselstein AG, Neuwisd. are coated with organosols of the above examples by the roI ler-coating process and baked for 12 minutes at 21Q°C. The dry film thickness was 10 g / m ^ .

The following tests were carried out on the coated substrates I and 11 : (A) Sterilization test at 121°C/30 minutes Using the following as simulated foodstuffs: (i) water (ii) 3% acetic acid solution (iii) 2% lactic acid solution (iv) 2% tartaric acid solution, the water absorption and blistering are evaluated.

(B) Sterilization test at 121°C/60 minutes Only with water as a simulated foodstuff.

The water absorption and blistering are evaluated.

(C) Sterilization test at 129°C/60 minutes Only with water as a simulated foodstuff. » -v 2210/ The water absorption and blistering are evaluated. (0) Flexibility test By the procedure using the Erichsen Model 471 drop impact tester (impact wedge bending test), 5 damage to the paint coating along the bend is evaluated.

(£) Sealing-heat resistance The coated metal substrate is brought to an object temperature of 255°C in a hot air stream for a period of 10 minutes- (Tested only on sub strate I). Discoloration and destruction of the paint film are evaluated.

The test results are summarized in Tables I and II which follow.

O \ Zi. JL i -d Table I ... Test results with substrate I Ex amp Ies Tests 1 2 3 4 5 Comparison example (A) Sterilization test 1 2 1 0C/ 30 ainutes i water 1 11-21 1 2 ii 3-t acetic acid 1 1 1-2 1 1 3 iii 2* lactic acid 1 1 1 1 1 3 iv 2% tartaric acid 1 1 1 1 1 3 (3) SteriIization test 121°C/60 minutes water 1 1 1-2 1 1 4 ( C ) Sterilization test 129°C/60 minutes water 1-2 1 1-2 1 1 (0) Flexibility test (impact wedge bending test! 1 2 12 2 3 (£) Sealing-heat res is tance 2 3 2 3 1 3 Rating: 1 = very good, 2 = good, 3 = satisfactory, 4 = adequate, 5 = unsatisfactory

Claims (17)

1. I 22*070;- 17 -;Table II ... Test results with substrate II;V i;Tests;Examples 1 2 3;Comparison example;(A) Sterilization test 121°C/30 minutes i water 11111 2;ii 3% acetic acid 3 2 3 2 1 5;ii i 2a lactic acid 2 1 2-3 2 1 3;iv 25! tartaric acid 1 1 1 1 1 2-3;(3) Sterilization test 121°C/60 minutes water;1 1;(C) Sterilization test 129°C/60 minutes water;1;1 1;(0) Flexibility test (impact wedge bend i ng test);1;2 1;O;Rating: 1 = adequate, 5;very good, 2 = good, 3 = unsatisfactory;= satisfactory, 4 =;O;221070;-18-;WHAT WE CLAIM IS:;1. Heat-curable organosol for forming firmly adhering, pore-free and sterilization-resistant coatings, containing a vinyl chloride homopolymer, a phenolic resin, a polyester, a diluent, a catalyst and, if appropriate, conventional additives, characterized in that it contains a) 20 to 50% by weight of the vinyl chloride homopolymer,;b) 1 to 15% by weight of the phenolic resin,;c) 1 to 15% by weight of an epoxide resin,;d) 4 to 20% by weight of a linear polyester based on aromatic and/or cyclic dicarboxylic acids and e) 25 to 60% by weight of the diluent.;
2. 2. Organosol according to Claim 1, characterized in that it contains, as the vinyl chloride homopolymer, a fine-grain, neutral homopolymer having a K value of 68 to 90 and a viscosity number of 115 to 230.;
3. 3. Organosol according to Claim 1, or Claim 2 characterized in that it contains, as the phenolic resin, a heat-curable, unplasticized phenol/formaldehyde resol resin of good compatibility with epoxide resins and vinyl chloride homopolymers.;
4. 4. An organosol as claimed in Claim 3 wherein said phenolic resin comprises an etherified cresol/formaldehyde resin.;
5. 5. Organosol according to any one of the preceding claims, characterized in that it contains, as the epoxide resin, an;I;/«*-s ? 21070 -19- epoxide resin having a number average molecular weight of 300 to 900 and a corresponding epoxide equivalent weight of 150 to 500.
6. 6. Organosol according to any one of the preceding claims characterized in that it contains, as the linear polyester, a thermoplastic saturated copolyester containing hydroxyl groups and based on phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, hexahydrophthalic acid, hexahydroisophthalic acid and/or hexahydroterephthalic acid and aliphatic and/or cyclic diols, or based on p-hydroxybenzoic acid.
7. 7. Organosol according to Claim 6, characterized in that the polyester comprises, as the aliphatic and/or cyclic diol, 1.2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1.3-butylene glycol, 1,4-butylene glycol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-2-methyl-l,3-propanediol, 1,6-hexamethylene glycol, l,2-bis-(hydroxymethyl)-cyclohexane, l,3-bis-(hydroxymethyl)-cyclohexane, l,4-bis(hydroxymethyl)-cyclohexane, bis-(hydroxymethyl)-tricyclodecane, 4,4'-dihydroxydiphenyl ether and/or 4,4' -dihydroxydiphenyl.
8. 8. Organosol according to claim 6 or 7, characterized in that the polyester has a molecular weight of 10,000 to 24,000 and a glass transition point of 60 to 80°C.
9. 9. Organosol according to any one of the preceding claims characterized in that it contains, as the diluent, at least one -20- ?22'2°1'0 70 o aromatic hydrocarbon, if appropriate as a mixture with terpene hydrocarbons, alcohols and/or ketones.
10. 10. Organosol according to any one of the preceding claims characterized in that it contains, as the catalyst, at least one representative from the group comprising formic acid, acetic acid, lactic acid, tartaric acid, citric acid, salicylic acid, phthalic acid, phosphoric acid or its esters, p-toluene-sulphonic acid, dodecylbenzenesulphonic acid, dinonyl-naphthalenedisulphonic acid, esters and/or chelates of titanic acid.
11. 11. An organosol as claimed in Claim 10 wherein said esters of titanic acid comprise butyl titanate or isopropyl titanate.
12. 12. An organosol as claimed in Claim 10 or Claim 11 wherein said chelates of titanic acid comprise titanium acetylacetonate.
13. 13. Organosol according to any one of the preceding claims, characterized in that it additionally contains 0.1 to 10% by weight of an aminoplast resin.
14. 14. Organosol according to Claim 13, characterized in that it contains, as the aminoplast resin, a benzoguanamine resin and/or triazine resin.
15. 15. Organosol according to any one of the preceding claims, characterized in that it additionally contains 0.5 to 10% by weight of a vinyl chloride copolymer in the form of a solution.
16. 16. Organosol according to Claim 15, characterized in that it contains, as the vinyl chloride copolymer, a vinyl chloride/ vinyl acetate/maleic acid copolymer or a vinyl chloride vinyl acetate/vinyl alcohol copolymer. O -21- 221070
17. 17. Use of the organosol according to any one of Claims 1 to 16 for producing a firmly adhering, pore-free and sterilization-resistant internal coating on foodstuff containers of tin-plated, untreated or surface-treated black plate, aluminium or aluminium alloys. o A.J. RAR& --/— - PER AGENTS FOR THE APPLICANT DATED THIS O