EP0769037A1

EP0769037A1 - Method of producing a sterically stabilized non-aqueous dispersion of a polyepoxide, and coating materials containing such a dispersion

Info

Publication number: EP0769037A1
Application number: EP95925787A
Authority: EP
Inventors: Lazaros Vogdanis; Klaus Cibura; Wolfgang Bremser
Original assignee: BASF Coatings GmbH; BASF Lacke und Farben AG
Current assignee: PPG Industries Inc
Priority date: 1994-07-02
Filing date: 1995-06-29
Publication date: 1997-04-23
Also published as: DE4423309A1; JPH10502403A; TR199500792A2; AU2978895A; CA2189864A1; WO1996001292A1; AU693915B2; BR9508204A

Abstract

The invention concerns a method of producing a sterically stabilized non-aqueous dispersion of a polyepoxide, the method calling for at least one epoxy resin (A) with at least two epoxy groups to be reacted, in an organic solvent in the presence of a dispersion stabilizer, with at least one diol (B) of the formula (I) HOROH, in which R is a group of the formula (II) in which D is a methylene or propylene group, and optionally with an additional component (C) having groups which are reactive towards epoxy or hydroxyl groups. The method is characterized in that 1) in a first stage, part of the epoxy resin (A) is reacted with an excess, relative to the amount of epoxy resin used in this stage (1), of the diol (B) of formula (I) and, optionally, of the additional component (C) and 2) the reaction product obtained in stage 1 is subsequently reacted with the remainder of the epoxy resin (A) and/or of the additional component (C) to give the required end product.

Description

Process for the production of a sterically stabilized, non-aqueous dispersion of a polyepoxide and coating compositions containing this dispersion

The present application relates to a process for the preparation of a sterically stabilized, nonaqueous dispersion of a polyepoxide, in which in an organic solvent in the presence of a dispersion stabilizer at least one epoxy resin (A) with on average at least 2 epoxy groups per molecule with min ¬ at least one diol (B) of the formula (I)

HOROH (I),

in which R is a group of the formula (II)

is, in which D is a methylene or a propylene group, and optionally with a further component (C) which has groups which are reactive toward epoxy or hydroxyl groups.

The present invention also relates to the non-aqueous dispersions prepared by this process and to the use of these dispersions in coating compositions, in particular for the coating of packaging.

EP-A-321 088 discloses a method for producing a sterically stabilized, non-aqueous dispersion of a polyepoxide according to the preamble of claim 1. The only disadvantage of this method is limited possible production of dispersions with a defined structure. The need for improvement in this process is the incorporation of additional resins. Finally, various mechanical properties of the resulting coatings also need to be improved.

The present invention is therefore based on the object of providing a method for producing a sterically stabilized, non-aqueous dispersion of a poly epoxide, in which the resulting dispersions have a defined structure. Furthermore, the dispersions should have a good incorporability / carrying capacity for one or more other resins. Furthermore, the resulting dispersions, when used as coating compositions for the interior painting of cans, should meet the requirements normally placed on these coating compositions, e.g. good adhesion and good flexibility, good sterilization resistance and freedom from pores in the resulting coatings and good application properties of the coating compositions. In addition, the process should be simple and inexpensive to carry out.

This object is surprisingly achieved by a method of the type mentioned at the outset, which is characterized in that

1.) in a first stage at least part of the

Epoxy resin component (A) with an excess of the diol (B) of formula (I) and optionally component (C), based on the amount of epoxy resin (A) used in step (1), and 2.) then the reaction product obtained in stage (1) is reacted with the remaining epoxy resin component (A) and / or component (C) to the desired end product.

The present invention also relates to the non-aqueous dispersions prepared by this process and the use of these dispersions in coating compositions, in particular for the coating of packaging.

The process according to the invention has the surprising advantage that the incorporation of further resins into the dispersions is improved. It is also advantageous that dispersions of resins with a defined structure are obtained with the process according to the invention. The flexibility, adhesion and resistance to sterilization of the resulting coatings are also improved. Finally, it is advantageous that the resulting dispersions, when used in coating compositions for the interior painting of cans, meet the requirements usually placed on these coating compositions, e.g. B. good application properties of the coating compositions.

The compounds used in the process according to the invention will now be explained in more detail below.

To prepare the non-aqueous dispersion of the poly epoxide, diols (B) of the formula (I)

HOROH (I),

used in which R is a group of the formula (II)

Bisphenol A is preferably used as the diol (B) of the formula (I).

Epoxy resins (A) suitable for producing the non-aqueous dispersion of the polyepoxide according to the invention are, in particular for stage (1) of the process, epoxides with an average of at least 2 epoxy groups per molecule. Epoxy resins which are liquid at room temperature are preferably used as component (A). Epoxy resins with an epoxide equivalent weight of 150 to 450, preferably 170 to 192, are particularly preferably used.

Aromatic epoxy resins (A) are particularly suitable for use in the process according to the invention, but aliphatic and araliphatic epoxy resins (A) are also suitable. Examples include diglycidyl ethers of polyphenols, diglycidyl ethers of dialcohols and diglycidyl esters of dicarboxylic acids. Diglycidyl ethers of polyphenols, in particular diglycidyl ethers of bisphenol A, and epoxidized novolak resins, particularly preferably epoxy resins based on bisphenol A, are used. Mixtures of different epoxy resins can of course also be used. Furthermore, it is of course also possible to use different epoxy resins (A) in stage (1) and stage (2) of the process according to the invention. In particular, it is also possible to use epoxy resins (A) in stage (2) of the process according to the invention a functionality <2, for example also monoepoxides.

Suitable epoxy resins (A) are, for example, the products commercially available under the following names

Bisphenol A base:

Epikote® 828 from Shell-Chemie;

DER® 330 and 333 from Dow Chemicals;

GY 250 from Ciba-Geigy.

Also suitable, for example, are the products commercially available under the following names based on epoxidized novolak resins:

XPY 307 and EPN 1139 from Ciba-Geigy and DEN® 438 from Dow Chemicals.

Also suitable are the epoxy compounds described in EP-A-321 088 on page 2, line 46, to page 5, line 36, and in Karsten, paint raw material tables, 9th edition, chapter 31, sections 31.1 and 31.2 .

Possibly. Small amounts, preferably less than 20% by weight, particularly preferably from 1 to 15% by weight, of the diol (B) and / or the epoxy resin component (A) can be replaced by other components (C) which are associated with the epoxy resin component (A) or with the reaction product obtained in stage (1) of the process. In particular, functional compounds are used as component (C). By using these further compounds (C), the physical properties of the resulting poly-epoxy resins can be specifically improved.

For example, as component (C) for the

Reaction with the epoxy resin, small amounts of adipic acid or dimer fatty acid or other flexibilizing components. Polyester, polyacrylates, diamines and fatty acid amide can also be used for this. Component (C) is preferably reacted in stage (1) of the process.

The reaction of the diol (B) of the formula (I) and optionally of the component (C) with the epoxy resin component (A) takes place in the presence of a steric dispersion stabilizer.

A steric dispersion stabilizer is a compound with a part which is associated with the epoxy resin to be stabilized (usually referred to as anchor component) and a part which is associated with the solvent (usually referred to as a solvated component).

Suitable steric dispersion stabilizers are known and are described, for example, in EP-A-321 088 on page 5, line 41, to page 6, line 1, and in K.E.J. Barrett, Dispersion Polymerization in Organic Media, John Wiley and Sons, 1975.

For example, dispersion stabilizers in which the anchor component is based on an acrylate polymer can be used in the process according to the invention. Suitable acrylate polymers are homopolymers and copolymers of (meth) acrylic acid alkyl esters (for example polymethyl methacrylate, polyethyl methacrylate, polymethyl acrylate, polyethyl acrylate, polyethyl acrylate / polyethyl methacrylate, etc.) and copolymers of (meth) acrylic acid alkyl esters and methacrylic acid and / or acrylic acid, where The proportion of polymerized (meth) acrylic acid is usually below 10% by weight. In addition, small amounts of other ethylenically unsaturated monomers can be polymerized into the copolymers, for example small amounts of crotonic acid, isocrotonic acid, maleic acid and / or alkyl esters of these acids.

The solvated component can be a poly-C6-18 alkyl ester, e.g. Poly-2-ethylhexyl acrylate, a

Polyester such as Poly-12-hydroxystearic acid, or a polymer, e.g. resins derived from polybutadiene.

The dispersion stabilizers can be prepared by the customarily used methods, for example by copolymerizing the reaction product of poly-12-hydroxystearic acid with glycidyl (meth) acrylate with the desired acrylate monomers or, for example, by polymerizing the desired anchor component with the solvated component desired polymer (for example derived from polybutadiene) is implemented.

Solvents which do not dissolve the resulting polyepoxide, for example non-polar organic solvents, are used in particular in the process according to the invention. Aliphatic hydrocarbons are preferably used as solvents, which may also contain up to 20% by weight of other solvents, e.g. aromatic hydrocarbons, e.g. Xylene and Solvesso® 150 may contain.

High-boiling aliphatic hydrocarbons, in particular those with a boiling point between 120 and 280 ° C., are preferably used as solvents. Examples of suitable solvents are Hydrosol® P 2300 EA from Deutsche Hydrocarbures GmbH, Exxold® 240-270, Norpar® 12 and Isopar® M from Deutsche Exxon Chemical GmbH. The amount of solvent is preferably selected so that the reaction of the diol (B) with the epoxy resin component (A) (stage (1)) at a dispersion solids content of 20 to 80% by weight, preferably 50 to 70% Wt .-% and the implementation of the reaction product

Step (1) with the diol (B) (step (2)) is carried out at a dispersion solids content of 25 to 85% by weight, preferably 55 to 75% by weight.

The reaction of the diol (B) with the epoxy resin component (A) is preferably carried out in the presence of a catalyst. Suitable catalysts are, for example, alkali metal carbonates, such as potassium and sodium carbonate, alkali metal hydroxides, such as sodium and potassium hydroxide, quaternary ammonium salts, amines, such as dibenzylamine, and trialkylphosphonium salts, such as e.g. Triphenylethylphosphonium iodide and triphenylethylphosphonium acetate. Triphenylethylphosphonium iodide is preferably used as the catalyst.

The reaction products produced by the process according to the invention (always referred to as polyepoxy resin in this application, regardless of the actual functional groups) usually have an equivalent weight of functional groups from 678 to infinity, preferably of more than 1000. If the reaction product of the first stage is reacted exclusively or predominantly with a diepoxide (A) in the second stage of the process, the polyepoxide resins prepared by the process according to the invention have epoxide groups as functional groups (epoxide equivalent weight is specified). If, on the other hand, the reaction product of the first stage is reacted in the second stage with a monoepoxide and / or component (C), the equivalent important the content of functional groups which are introduced into the resin by these components.

It is essential to the invention that the reaction of the epoxy resin component (A) with the diol (B) of the formula (I) takes place in a two-stage process.

In the first stage of the process according to the invention, part of the epoxy resin component (A) is first mixed with an excess of at least one diol (B) of the formula (I) and, if appropriate, component (C), based on those in this stage (1) of the process amount of epoxy resin component (A) used. An essentially phenoxy-terminated product is obtained. The amounts of epoxy resin component (A) and diol (B) of the formula (I) are preferably chosen so that 1 ol epoxy resin component with 3 to 1.001 mol, preferably 1.5 to 1.02 mol, of at least one diol (B), is implemented.

The reaction of the epoxy resin component (A) with the diol (s) (B) and optionally (C) in the first stage of the process according to the invention is preferably carried out in that the epoxy resin or diols and the diols and optionally (C) the dispersion stabilizer and the solvent are combined and slowly heated with stirring. It is preferably heated to temperatures between 80 and 140 ° C. At this slightly elevated temperature, it is preferred to disperse for some time first. Thereafter, the catalyst is added if necessary and heated to the desired reaction temperature. The reaction of the epoxy resin with the diol and optionally (C) is usually carried out at a temperature between 120 and 250 ° C., preferably at a temperature between 160 and 180 ° C. In addition, however, in the first stage of the process according to the invention it is also possible to initially introduce the epoxy resin component (A) with the solvent and the dispersion stabilizer and by stirring and, if appropriate, slightly heating, preferably to temperatures between 80 and 140 ° C to disperse the epoxy resin component. The dispersion can then be heated to the desired reaction temperature and the diol (B) and optionally (C) added.

The reaction of the epoxy resin component (A) with the diol (s) (B) is preferably continued in the first stage of the process until the resulting reaction product has a phenoxy equivalent weight of at least 256, preferably at least 682 and particularly preferably at most 20,000. having.

In a second stage, the phenoxy-terminated reaction product obtained in stage (1) is then reacted with the remaining epoxy resin component (A) and / or possibly further modifying components to give the desired end product. In the second stage, the product obtained in stage (1) is preferably reacted with the remaining epoxy resin component (A).

The reaction with the remaining epoxy resin component and / or possibly further modifying components (C) is preferably carried out in that the epoxy resin and possibly the further modifying components are slowly added at an elevated temperature, preferably at a temperature of 60 to 120 ° C be dropped. It is also possible to add the remaining epoxy resin component in step 2 of the process all at once. After the addition of the epoxy resin or the addition of the modifying components, catalyst is preferably added again and the temperature is increased, preferably to values between 160 and 180 ° C. Then the reaction is continued until the desired degree of conversion is reached.

In addition, however, it is also possible to add the remaining epoxy resin component and / or the further modifying components (C) at room temperature to the phenoxy-terminated product obtained in stage (1) of the process, and then to heat them to a temperature of 120 to 180 ° C to disperse and continue the reaction until the desired degree of conversion is reached.

The dispersions of polyepoxy resins produced by the process according to the invention are particularly suitable for use in coating compositions. In addition to these non-aqueous, sterically stabilized dispersions, these coating compositions can also contain further binding agents, further customary solvents, optionally further resins, optionally pigments and / or fillers and customary auxiliaries and additives in customary amounts.

The coating compositions preferably contain up to 100% by weight, particularly preferably 60 to 100% by weight, of the non-aqueous dispersion, 0 to 40% by weight of further binders, 0 to 40% by weight of further resins, 30 to 80% by weight of solvent (including the solvent content of the non-aqueous dispersion), 0 to 50% by weight of pigments and / or fillers and 0 to 10% by weight of conventional auxiliaries and additives, in each case based on the total weight of the coating agent.

The coating compositions are preferably used for coating packaging, in particular for coating food packaging. The packaging can come from a wide variety Materials exist and have a wide variety of geometries. The materials in particular are black sheet, tinplate and various iron alloys, which may be provided with a passivation layer based on nickel, chromium and zinc compounds. The packaging can be coated in the form of, for example, half-can parts, that is to say hulls and lids, as 3-part cans and as 2-part, deep-drawn or otherwise deep-drawn cans, such as, for example, beverage and food cans.

The coating compositions according to the invention cure in the object temperature range from 150 to 400 ° C. for a period of from 2 s to 15 min. They can be applied by rolling, knife coating, brushing, spraying, flooding or dipping by means of conventional devices, the film then being cured to form a firmly adhering coating. The coating compositions are preferably applied by roller application.

The invention will now be explained in more detail using exemplary embodiments. All information on parts and percentages are weight information unless expressly stated otherwise.

Production of a dispersion stabilizer

In the inlet 1

18.774 parts of methyl methacrylate and 1.198 parts of methacrylic acid

weighed in and mixed.

In the inlet 2 0.533 parts dibenzoyl peroxide (75% in water) and 9.910 parts xylene

weighed in and mixed.

Then be

29.724 parts of xylene

19,974 parts of a commercially available solvent-free

Polymers based on butadiene with a number average molecular weight of approx. 5000, with 15-20% vinyl double bonds, 50-60% 1,4-trans double bonds, 25-35% 1,4-cis double bonds and an iodine number of approx. 450 (commercial product Lithene N4-5000 from Chemetall GmbH, Frankfurt)

19.794 parts of a commercially available mixture of paraffinic and naphthenic hydrocarbons in the range C15-C17 with a boiling range between 230 and 265 ° C (commercial product Hydrosol P 230 EA from Deutsche Hydrocarbures GmbH)

mixed and heated to 123 ° C. with stirring. Then feed 1 and feed 2 are metered in simultaneously, but separately, within 1.5 h

0.093 parts of tert-butyl per-2-ethylhexanoate

added and the temperature kept at 123 ° C for 1 h. Then 9.910 parts of solvent are distilled off under a slight vacuum. Then 9.910 parts of a commercially available mixture of paraffinic and naphthenic hydrocarbons in the range C15-C17 with a boiling range between 230 and 265 ° C (Han- Delicate product Hydrosol P 230 EA from Deutsche Hydrocarbures GmbH) was added dropwise over 30 minutes at a temperature of 122-124 ° C. Then it is cooled.

The solution of the dispersion stabilizer thus obtained has a solids content (60 min 130 ° C.) of 38.5%, an acid number of 21 mgKOH / g and a viscosity of 2.2 + 0.2 dPa.s (ICI plate / cone viscometer , 23 ° C).

example 1

28,172 parts of a commercially available liquid epoxy resin based on bisphenol A with an epoxide equivalent weight of 188 and a molecular weight of 350-380 (commercial product Epikote® 880 from Shell Chemie)

0.455 parts of a commercially available liquid epoxy resin based on bisphenol A with an epoxide equivalent weight of 188 and a molecular weight of 350-380 (commercial product Epikote® 880 from Shell Chemie)

20,526 parts of bisphenol A

14.964 parts of the dispersion stabilizer described above and

27.389 parts of a commercially available mixture of paraffinic and naphthenic hydrocarbons in the range C15-C17 with a boiling range between 230 and 265 ° C (commercial product Hydrosol P

230 EA from Deutsche Hydrocarbures GmbH) are mixed and heated to 120 ° C. with slow stirring (approx. 80 revolutions per minute). Then the stirrer speed is increased to 300 revolutions per minute and dispersed for 1 hour. Then be

0.018 parts of phosphonium ethyl triphenyl iodide as a catalyst

added and the temperature increased to 170 ° C. It is held at this temperature until the phenoxy equivalent weight is 1990. Then it is cooled to 120 ° C. and it becomes

8.464 parts of a commercially available liquid epoxy resin based on bisphenol A with an epoxide equivalent weight of 188 and a molecular weight of 350-380 (commercial product Epikote® 880 from Shell Chemie), heated to 80 to 120 ° C.

added dropwise within 1 h (stage II). The mixture is then dispersed for one hour. Then be

0.012 parts of phosphonium ethyl triphenyl iodide as a catalyst

added and the dispersion is heated to 170 ° C. The temperature is maintained until the desired epoxide equivalent weight of 3800 g / mol is reached. Then the mixture is cooled and the product is filtered through a nylon mesh (mesh size 30 μm).

The dispersion obtained has a solids content (90 min 180 ^β C) of 63.5% and a viscosity (ICI plate / cone viscometer, 23 ^β C) of 2.9 dPa.s. The polyepoxide obtained has a number-average molecule Lar weight of 11 375, a weight average molecular weight of 78 069 and a non-uniformity of 6.9 (each determined by gel permeation chromatography against polystyrene standard). The dispersion obtained in this way has a shelf life of more than 30 days at 23 ° C.

Comparative example 1

37.683 parts of a commercially available liquid epoxy resin based on bisphenol A with an epoxide equivalent weight of 188 and a molecular weight of 350-380 (commercial product Epikote® 880 from Shell Chemie)

0.393 parts of a commercially available liquid epoxy resin based on bisphenol A with an epoxide equivalent weight of 188 and a molecular weight of 350-380 (commercial product Epikote® 880 from Shell Chemie)

20.904 parts of bisphenol A

14.782 parts of the dispersion stabilizer described above,

0.119 parts of phosphonium ethyl triphenyl iodide as catalyst and

18.977 parts of a commercially available mixture of paraffinic and naphthenic hydrocarbons in the range C15-C17 with a boiling range between 230 and 265 ° C (commercial product Hydrosol P 230 EA from Deutsche Hydrocarbures GmbH) are mixed and heated to 120 ° C. with slow stirring (approx. 80 revolutions per minute). Then the stirrer speed is increased to 300 revolutions per minute and dispersed for 1 hour. Then the temperature is increased to 170 ° C. It is kept at this temperature until the epoxide equivalent weight is 3800. Then it is cooled to 160 ° C. and it becomes

7.142 parts of a commercially available mixture of paraffinic and naphthenic hydrocarbons in the range C15-C17 with a boiling range between 230 and 265 ° C (commercial product Hydrosol P 230 EA from Deutsche Hydrocarbures GmbH)

added dropwise within 30 min. It is then cooled and the product is filtered through a nylon mesh (mesh size 30 μm).

The dispersion obtained has a solids content (90 min 180 ° C.) of 60.3%. The polyepoxide obtained has a number average molecular weight of 10,305, a weight average molecular weight of 43,609 and a non-uniformity of 4.2 (in each case determined by gel permeation chromatography against the polystyrene standard). The dispersion thus obtained has a

Storage stability at 23 ^β C of more than 30 days.

Claims

Claimant

1. A process for the preparation of a sterically stabilized, non-aqueous dispersion of a polyepoxide, in which in an organic solvent in the presence of a dispersion stabilizer at least one epoxy resin (A) with on average at least 2 epoxy groups per molecule with at least one diol (B) Formula (I)

HOROH (I),

in which R is a group of the formula (II)

is in which D is a methylene or a propylene group and, if appropriate, is reacted with a further component (C) which has groups which are reactive toward epoxy or hydroxyl groups, characterized in that

1.) in a first stage at least part of the

Epoxy resin component (A) is reacted with an excess of the diol (B) of the formula (I) and, if appropriate, the component (C), based on the amount of epoxy resin (A) used in this step (1), and

2.) then the reaction product obtained in stage (1) is reacted with the remaining epoxy resin component (A) and / or component (C) to the desired end product. 2. The method according to claim 1, characterized in that at least in stage (l) of the process as component (A) at least one liquid epoxy resin is used at room temperature.

3. The method according to claim 1 or 2, characterized gekenn¬ characterized in that as component (A) at least one epoxy resin with an epoxy equivalent weight of 150 to 450 and preferably at least one epoxy resin based on bisphenol A, is used.

4. The method according to any one of claims 1 to 3, characterized in that small amounts of the diol (B) and / or the epoxy resin component (A) are replaced by other, difunctional compounds (C).

5. The method according to any one of claims 1 to 4, characterized in that the reaction product obtained in stage (1) of the method has a phenoxy equivalent weight of at least 256, preferably at least 682 and particularly preferably of at most 20,000 and / or that in stage (2 ) of the process obtained poly epoxy resin has an equivalent weight of functional groups from 678 to infinity.

6. The method according to any one of claims 1 to 5, characterized in that the reactions in step (1) of the method at a dispersion solids content of 20 to 80 wt .-%, preferably from 50 to 70 wt .-%, and in step ( 2) at a dispersion solids content of 25 to 85% by weight, preferably 55 to 75% by weight.

7. The method according to any one of claims 1 to 6, characterized in that in step (1) of method 1 mol of the epoxy resin component with 3 to 1.001 mol, preferably with 1.5 to 1.02 mol, of the diol component.

8. The method according to any one of claims 1 to 7, characterized in that a stabilizer, which comprises a sol¬ vatised component derived from polybutadiene, and preferably a stabilizer, which has an anchor component associated with the epoxy resin, in particular an anchor component, which is a homopolymer of methyl methacrylate or a copolymer of methyl methacrylate and acrylic acid and / or methacrylic acid.

9. The method according to any one of claims 1 to 8, characterized in that high-boiling aliphatic hydrocarbons, preferably aliphatic hydrocarbons with a boiling point between 120 and 280 "C, are used as solvents.

10. Sterically stabilized, non-aqueous dispersion of a polyepoxide prepared by a process according to one of claims 1 to 9.

11. Coating agent based on a sterically stabilized, non-aqueous dispersion of a polyepoxide, characterized in that it contains the dispersion according to claim 10.

12. Use of the coating compositions according to claim 11 for coating packaging, in particular for coating food packaging containers.