AU693915B2

AU693915B2 - Method of producing a sterically stabilized non-aqueous dispersion of a polyepoxide, and coating materials containing such a dispersion

Info

Publication number: AU693915B2
Application number: AU29788/95A
Authority: AU
Inventors: Wolfgang Bremser; Klaus Cibura; Lazaros Vogdanis
Original assignee: BASF Lacke und Farben AG
Current assignee: BASF Farben und Fasern AG
Priority date: 1994-07-02
Filing date: 1995-06-29
Publication date: 1998-07-09
Anticipated expiration: 2015-06-29
Also published as: TR199500792A2; CA2189864A1; BR9508204A; EP0769037A1; AU2978895A; DE4423309A1; WO1996001292A1; JPH10502403A

Description

PAT 94 462 27.06.1994 BASF Lacke Farben Aktiengesellschaft, Minster Process for the preparation of a sterically stabilized, nonaqueous 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 at least one epoxy resin having on average at least 2 epoxide groups per molecule is reacted in an organic solvent in the presence of a dispersion stabilizer with at least one diol of the formula (I) HOROH (I) in which R is a group of the formula (II) D (II) in which D is a methylene or a propylene group, and if desired with a further component which has groups which are reactive toward epoxide or hydroxyl groups.

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

2 EP-A-321 088 discloses a process for the preparation of a sterically stabilized, nonaqueous dispersion of a polyepoxide in accordance with the precharacterizing clause of claim 1. A disadvantage of this process is the limited possibility for the preparation of dispersions having a defined structure. A parameter in need of improvement in this process is the ease of incorporation of further i resins. Finally, various mechanical properties of the resulting coatings are also in need of improvement.

The object of the present invention is therefore to provide a process for the preparation of a sterically stabilized, nonaqueous dispersion of a polyepoxide, in which process the resulting dispersions have a defined structure. In addition, the dispersions should exhibit good ease of incorporation/tolerance of one or more further resins.

Furthermore, when used as coating compositions for the interior coating of cans, the resulting dispersions should meet the requirements which are normally placed on these S" 20 coating compositions, for example good adhesion and good flexibility, good sterilization resistance and freedom from pores of the resulting coatings, and good application properties of the coating compositions. Moreover, the process should be simple and inexpensive to carry out.

*;25 According to the present invention there is provided a S" process for the preparation of a sterically stabilized, nonaqueous dispersion of a polyepoxide, in which at least one epoxy resin having on average at least 2 epoxide groups per molecule is reacted in an organic solvent in the presence of a dispersion stabilizer with at least one diol of the formula (I) HOROH

(I)

in which R is a group of the formula (II) S3 l KH:\Sigrid\Keep\patents\29788-95.doc 27/05/98 -3-

QDQ

in which D is a methylene or a propylene group, in which: in a first step at least a portion of the lit epoxy resin component is reacted with an excess of the diol of the formula based on the quantity of epoxy resin employed in this step and (ii) subsequently the reaction product obtained in step is reacted with the rest of the epoxy resin component to give the j desired end product.

The process according to the invention has the surprising K :advantage that the ease of incorporation of further resins 4 0 into the dispersions is improved. A further advantage is that, with the process according to the invention, dispersions of resins having a defined structure are obtained. There are improvements, moreover, in the flexibility, adhesion and sterilization resistance of the resulting coatings. Finally, it is advantageous that the resulting dispersions, when used in coating compositions for the interior coating of cans, meet the requirements which are normally UiHt\Sigrid\IeeWpptents\29788-95.doc 27/05/98

~ATO

4 placed on these coating compositions, for example good application properties of the coating compositions.

In the text below, the compounds employed in the process according to the invention are first of all described in more detail.

For the preparation of the nonaqueous dispersion of the polyepoxide, diols of the formula (I) HOROH

(I)

are employed in which R is a group of the formula (II) Q °D (II) in which D is a methylene or a propylene group.

As diol of the formula it is preferred to Semploy bisphenol A.

Epoxy resins which are suitable for the preparation of the novel nonaqueous dispersion of the polyepoxide are, in particular for step of the process, epoxides having on average at least 2 epoxide groups per molecule. As component i(A) it is preferred to employ epoxy resins which are liquid at room temperature. It is particularly preferred to employ I I 5 epoxy resins having an epoxide equivalent weight of from 150 to 450, preferably from 170 to 192.

Particularly suitable epoxy resins for use in the V 5 process according to the invention are aromatic epoxy L resins but also aliphatic and araliphatic epoxy resins Examples which may be mentioned are V diglycidyl ethers of polyphenols, diglycidyl ethers of V dialcohols and diglycidyl esters of dicarboxylic acids.

It is preferred to employ diglycidyl ethers of polyphenols, especially bisphenol A diglycidyl ether, and epoxidized novolak resins, and particular preference is given to employing epoxy resins based on bisphenol A.

It is, of course, also possible to employ mixtures of different epoxy resins. In addition, it is of course also possible to employ different epoxy resins in step and step of the process according to the invention. In particular, it is possible to employ in step of the process according to the invention epoxy resins including those having a functionality 2, for example, including monoepoxides.

Examples of suitable epoxy resins are the products based on bisphenol A which are commercially available under the following names: Epikote® 828 from Shell-Chemie; DER® 330 and 333 from Dow Chemicals; GY 250 from Ciba-Geigy.

6 Further suitable examples are the products, based on Iepoxidized novolak resins, which are commercially available under the following names: SXPY 307 and EPN 1139 from Ciba-Geigy and DEN® 438 from Dow Chemicals.

iAlso suitable, in addition, are the epoxide compounds I described in EP-A-321 088 on page 2, line 46 to page Sline 36, and in Karsten, Lackrohstofftabellen, 9th 10 edition, Capital [sic] 31, sections 31.1 and 31.2.

If desired, small quantities -preferably less than by weight, particularly preferably from 1 to 15 by weight of the diol and/or of the epoxy resin component can be replaced by other components (C) which are reacted with the epoxy resin component (A) and/or with the reaction product obtained in step (1) of the process. As component difunctional compounds are employed in particular. By the use of these further compounds it is possible in a targeted manner to improve the physical properties of the polyepoxide resins which are produced.

For example, in this way, small quantities of adipic acid or dimeric fatty acid or other flexibilizing components can be incorporated as component for the reaction with the epoxy resin. Furthermore, polyesters, polyacrylates, diamines and fatty acid amides can be -employed for this purpose. Component is preferably ~~ircr;~xaa~a~~L~" n~^.IY L fIacs^ 7reacted in step of the process.

The reaction of the diol of the formula and, if desired, of component with the epoxy resin component is carried out in the presence of a steric dispersion stabilizer.

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

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

For example, in the process according to the invention it is possible to employ dispersion stabilizers in which the anchor component is based on an acrylate polymer. Suitable acrylate polymers are homo- and copolymers of alkyl (meth)acrylates polymethyl methacrylate, polyethyl methcrylate [sic], polymethyl acrylate, polyethyl acrylate, polyethyl acrylate/polyethyl methacrylate etc.) and copolymers of alkyl (meth)acrylates and methacrylic and/or acrylic acid, in which the proportion of copolymerized (meth)acrylic 4

I

I 8 acid is usually below 10 by weight. Furthermore, small proportions of other ethylenically unsaturated monomers may also be copolymerized into the copolymers, Sfor example small quantities of crotonic acid,

I

5 isocrotonic acid, maleic acid and/or alkyl esters of j these acids.

I!

The solvated component may be a poly-C6-18-alkyl ester, 'for example poly-2-ethylhexyl acrylate, a polyester, for example poly-12-hydroxystearic acid, or an addition polymer, for example resins derived from polybutadiene.

The dispersion stabilizers may be prepared by the methods which are conventionally employed, by copolymerizing, for example, the reaction product of poly-12-hydroxystearic acid and glycidyl (meth)acrylate with the desired acrylate monomers, or by reacting, for example, the addition polymer which is desired as anchor component with the polymer (derived for example from polybutadiene) which is desired as solvated component.

The solvents employed in the process according to the invention are in particular those which do not dissolve the polyepoxide formed, for example apolar organic solvents. Preferred solvents which are employed are aliphatic hydrocarbons which may if desired also contain up to 20 by weight of other solvents, for I example aromatic hydrocarbons such as, for example, S- 9 xylene and Solvesso® 150.

As solvents it is preferred to employ high-boiling aliphatic hydrocarbons, especially those having a boiling point of between 120 and 2800C. 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 quantity of solvent is preferably chosen such that the reaction of the diol with the epoxy resin component (step is carried out at a dispersion solids content of from 20 to 80 by weight, preferably from 50 to 70 by weight, and the reaction of the reaction product of step with the diol (step is carried out at a dispersion solids content of from 25 to 85 by weight, preferably from 55 to 75 by weight.

The reaction of the diol with the epoxy resin component is preferably carried out in the presence of a catalyst. Examples of suitable catalysts are alkali metal carbonates, such as potassium carbonate and sodium carbonate, alkali metal hydroxides, such as sodium hydroxide and potassium hydroxide, quaternary ammonium salts, amines, such as dibenzylamine, and trialkylphosphonium salts, for example triphenylethylphosphonium iodide and triphenylethylphosphonium acetate. The catalyst preferably employed is triphenylethylphosphonium f-*-~~L1=e~lsr;FaF~ 10 iodide.

I

I I .1 It It The reaction products prepared with the process according to the invention (in this application referred to in every case as polyepoxide resin, irrespective of the actual functional groups) usually have an equivalent weight of functional groups of from 678 to infinity, preferably more than 1000. If, in the second step of the process, the reaction product from the first step is reacted exclusively or predominantly with a diepoxide then the polyepoxide resins prepared with the process according to the invention exhibit epoxide groups as functional groups (epoxide equivalent weight is indicated). If, in contrast, the reaction product from the first step is reacted in the second step with a monoepoxide and/or with component then the equivalent weight indicates the content of functional groups which are incorporated into the resin by these components.

It is essential to the invention that the reaction of the epoxy resin component with the diol of the formula is carried out in a two-step process.

In ,the first step of the process according to the invention, a portion of the epoxy resin component (A) is reacted first of all with an excess of at least one diol of the formula and, if desired, of component based on the quantity of epoxy resin Ii 1 I component employed in this step of the process.

In this case, an essentially phenoxy-terminated product is obtained. In this context the quantities of epoxy resin component and diol of the formula are preferably chosen such that 1 mol of epoxy resin component is reacted with from 3 to 1.001 mol, I preferably from 1.5 to 1.02 mol, of at least one diol J

/I

The reaction of the epoxy resin component with the ii diol(s) and, if desired, in the first step of the process according to the invention is preferably carried out by combining the epoxy resin(s), the diol(s) and, if desired, the dispersion stabilizer and the solvent and slowly heating the mixture with stirring. It is preferably heated to temperatures between 80 and 140°C. At this slightly elevated temperature, it is preferred first of all to carry out dispersion for some time. Subsequently, the catalyst is added if desired and the mixture is heated to the desired reaction temperature. The reaction of the epoxy resin with the diol and, if desired, is in this case usually carried out at a temperature of between 120 and 250 0 C, preferably at a temperature of between 160 and 180 0

C.

In addition, however, in the first step of the process according to the invention it is also possible first of all to introduce the epoxy resin component as I 12 initial charge with the solvent and the dispersion stabilizer and, by stirring and gentle heating if appropriate, preferably at temperatures of between and 140 0 C, to disperse the epoxy resin component. The dispersion can then be heated to the desired reaction temperature and the diol and, if desired, can be added.

The reaction of the epoxy resin component with the diol(s) in the first step of the process is preferably continued until the reaction product formed has a phenoxy equivalent weight of at least 256, preferably of at least 682 and particularly preferably of not more than 20,000.

In a second step, the phenoxy-terminated reaction product obtained in step is then reacted with the rest of the epoxy resin component and/or, if appropriate, further modifying components to give the desired end product. In the second step the product obtained in step is preferably reacted with the rest of the epoxy resin component (A) The reaction with the rest of the epoxy resin component and/or, if appropriate, further modifying components is preferably carried out by slow dropwise addition of the epoxy resin and, if desired, of the further modifying components at an elevated temperature, Spreferably at a temperature of from 60 to 120 0 C. It is -13also possible to add the rest of the epoxy resin component in one go in step 2 of the process.

Preferably, after the end of the addition of epoxy resin or of the modifying components, catalyst is again added and the temperature is increased, preferably to values of between 160 and 180 0 C. The reaction is then continued until the desired degree of conversion is reached.

In addition, however, it is also possible to add the rest of the epoxy resin component and/or the further modifying components at room temperature to the phenoxy- terminated product obtained in step of the process, then to heat the mixture to a temperature of from 120 to 180 0 C, to carry out dispersion and to continue the reaction until the desired degree of conversion is reached.I The dispersions of polyepoxide resins which are prepared by the process according to the invention are particularly suitable for use in coating compositions.

In addition to these nonaqueous, sterically stabilized dispersions, said coating compositions may also contain further binders, further conventional solvents, furtherI resins if desired, pigments and/or fillers if desired, and conventional auxiliaries and additives in convent ional quantities.

The coating compositions preferably contain up to 100

~DII~-~

If i

E

f i 4n-YII_ IIYII liI--0 U--C~ 14 by weight, particularly preferably from 60 to 100 by weight, of the nonaqueous dispersion, from 0 to 40 by weight of further binders, from 0 to 40 by weight of further resins, from 30 to 80 by weight of solvent (including the solvent component of the nonaqueous dispersion), from 0 to 50 by weight of pigments and/or fillers, and from 0 to 10 by weight of conventional auxiliaries and additives, based in each case on the overall weight of the coating composition.

The coating compositions are preferably employed for the coating of packaging containers, in particular for the coating of foodstuffs packaging. These packaging containers may consist of a very wide variety of materials and may have a very wide range of geometries.

Suitable materials are, in particular, tin-free steel, tin plate and various iron alloys, which are provided, if desired, with a passivating layer based on nickel compounds, chromium compounds and zinc compounds. The packaging containers may be coated in the form, for example, of can half-pieces, that is bodies and tops, as 3-piece cans and as 2-piece, drawn and wall-ironed or otherwise deep-drawn cans, for example beverage and preserve cans.

The coating compositions according to the invention cure within the substrate temperature range of from 150 to 400 0 C over a period of from 2 s to 15 min. They can rV Rq be applied by rolling, knife-coating, brushing, 7'~t

~A~

naar~IF1II1"--~ 15 i spraying, flow-coating or dipping by means of conventional devices, with the film subsequently being cured to give a firmly adhering coating. The coating compositions are preferably applied by roller application.

The invention is now illustrated in more detail with reference to implementation examples. In these examples all parts and percentages are by weight unless expressly stated otherwise.

Preparation of a dispersion stabilizer 18.774 parts of methyl methacrylate and 1.198 parts of methacrylic acid are weighed into feed 1 and mixed.

0.533 part of dibenzoyl peroxide (75 strength in water) and 9.910 parts of xylene are weighed into feed 2 and mixed.

Then 29.724 parts of xylene R 19.974 parts of a commercial, solvent-free polymer 16 based on butadiene, having a number-average molecular weight of about 5000, containing vinyl double bonds, 50-60 1,4-trans double bonds, 25-35 1,4-cis double bonds and having an iodine number of about 450 (commercial product Lithene N4-5000 from Chemetall GmbH, Frankfurt) ii S19.794 parts of a commercial mixture of paraffinic and I 10 naphthenic C15-C17 hydrocarbons having a boiling range of between 230 and 265 0 C (commeri cial product Hydrosol P 230 EA from Deutsche i Hydrocarbures GmbH) are mixed and the mixture is heated to 123 0 C with stirring. Then feed 1 and feed 2 are metered in simultaneously but separately over the course of 1.5 h.

Subsequently, 0.093 part of tert-butyl per-2-ethylhexanoate are added and the temperature is held at 1230C for 1 h.

Afterwards, 9.910 parts of solvent are distilled off under a slight vacuum. Then 9.910 parts of a commercial mixture of paraffinic and naphthenic C15-C17 hydrocarbons having a boiling range of between 230 and 265 0

C

(commercial product Hydrosol P 230 EA from Deutsche Hydrocarbures GmbH) are added dropwise with stirring at RA,- a temperature of 122-124 0 C over the course of 30 min.

1-

C

LI- L IW-~ i -I 1 C nr~ ~-L1I-r -17 The mixture is then cooled.

The solution thus obtained of the dispersion stabilizer has a solids content (60 min 130 0 C) of 38.5 an acid number of 21 mg of KOH/g and a viscosity of 2.2 S0.2 dPa.s (ICI plate/cone viscometer, 23 0

C).

Example 1 28.172 parts of a commercial liquid epoxy resin based on bisphenol A, having an epoxide equivalent weight of 188 and a molecular weight of 350 380 (commercial product Epikote® 880 from Shell Chemie) 0.455 part of a commercial liquid epoxy resin based on bisphenol A, having an epoxide equivalent weight of 188 and a molecular weight of 350 380 (commercial product Epikote® 880 from Shell Chemie) [sic] 20.526 parts of bisphenol A 14.964 parts of the above-described dispersion stabilizer, and 27.389 parts of a commercial mixture of paraffinic and naphthenic C15-C17 hydrocarbons having a 4 boiling range of between 230 and 265 0

C

f beweJn 18 (commercial product Hydrosol P 230 EA from Deutsche Hydrocarbures GmbH) are mixed, and the mixture is heated to 120 0 C with slow stirring (about 80 revolutions per minute). The stirrer speed i.s then raised to 300 revolutions per minute and dispersion is carried out for 1 h. Subsequently, 0.018 part of phosphoniumethyltriphenyl iodide as catalyst is added and the temperature is raised to 170 0 C. The mixture is held at this temperature until the phenoxy equivalent weight is 1990. The mixture is then cooled to 120 0 C, and 8.464 parts of a commercial liquid epoxy resin based on bisphenol A, having an epoxide equivalent weight of 188 and a molecular weight of 350 380 (commercial product Epikote® 880 from Shell Chemie), heated at from 80 to 120 0

C,

are added dropwise over the course of 1 h (step II) SThe mixture is subsequently dispersed for one hour.

Then 0.012 part of phosphoniumethyltriphenyl iodide as Scatalyst is added and the dispersion is heated to 1700C. The 19 temperature is maintained until the desired epoxide equivalent weight of 3800 g/mol is reached. The mixture is then cooled and the product is filtered through a nylon net (mesh size 30 gm).

The dispersion obtained has a solids content (90 min 180 0 C) of 63.5 and a viscosity (ICI plate/cone viscometer, 23 0 C) of 2.9 dPa.s, The resulting polyepoxide has a number-average molecular weight of 11 375, a weight-average molecular weight of 78 069 and a polydispersity of 6.9 (determined in each case by gel permeation chromatography against a polystyrene standard) The dispersion obtained in this way has a shelf life at 23 0 C of more than 30 days.

Comparison Example 1 37.683 parts of a commercial liquid epoxy resin based on bisphenol A, having an epoxide equivalent weight of 188 and a molecular weight of 350 380 (commercial product Epikote 880 from Shell Chemie) 0.393 part of a commercial liquid epoxy resin based on bisphenol A, having an epoxide equivalent weight of 188 and a molecular weight of 350 380 (commercial product Epikote® 880 from Shell Chemie) [sic] 20 20.904 parts of bisphenol A 14.782 parts of the above-described dispersion stabilizer, 0.119 part of phosphoniumethyltriphenyl iodide as catalyst, and 18.977 parts of a commercial mixture of paraffinic and naphthenic C15-C17 hydrocarbons having a boiling range of between 230 and 2650C (commer- (j cial product Hydrosol P 230 EA from Deutsche Hydrocarbures GmbH) are mixed, and the mixture is heated to 120 0 C with slow stirring (about 80 revolutions per minute). The stirrer j speed is then raised to 300 revolutions per minute and dispersion is carried out for 1 h. Subsequently, the temperature is raised to 170 0 C. The mixture is held at this temperature until the epoxide equivalent weight is 3800. The mixture is then cooled to 160 0 C, and 7.142 parts of a commercial mixture of paraffinic and naphthenic C15-C17 hydrocarbons having a boiling range of between 230 and 265 0

C

(commercial product Hydrosol P 230 EA from Deutsche Hydrocarbures GmbH), are added dropwise over the course of 30 min. The

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H

mixture is the through a nylon The dispersion 180 0 C) of 60.: number-average V average molecul of 4.2 (determ (i chromatography j dispersion obta Ij 10 23 0 C of more the 21 n cooled and the product is filtered net (mesh size 30 ym).

obtained has a solids content (90 min 3 The resulting polyepoxide has a molecular weight of 10 305, a weightar weight of 43 609 and a polydispersity lined in each case by gel permeation against a polystyrene standard). The ined in this way has a shelf life at an 30 days.

Claims

9. Oktober 1995 1-25. 10. NaeudPosunisebrift der Intenationale Recherchenbehdrde Bevolct itrBdcsue Nam Eropaitcs Patnat 58IS Patenlain 2{ l tt NITl. (3F.10) 4 0Tx.31651 po rI, OS v n Fax 31-70) 340-3016O'u lv n T Formblatt FCTflSAJ2IO (BlettS 2) (lull IM2) Seite 1 von 2 INTERNATIONALER RECHERCHENBERICHT F PPr, inles Aktenzetchen PCT/EP 95/02531 C.(Formemung) AIS WESENTICH ANG[LSE14ENE UNTI3RLAGEN Kategonc* I Bezeichnung der Vcwbffentlichung, soweit crforderlich =nter Aripabc der in Betracht kornmendcn Teile [57dr.Anspruch Nr, DATABASE WPI Derwent Publications Ltd., London, GB; AN 86-135556(21) JP,A,61 073 726 (NIPPON OILS AND FATS KK) 15. April 1986 siehe Zusammenfassung WO,A,93 04104 (DOW CHEMICAL) 4. Marz 1993 siehe Anspruch 1 siehe Scite 16, Zeile 36 Zeile 37 1,10 1 Fornbist PcTOSA/213 (Foruitung Von Iatt 2) piull 1"2) Seite 2 von 2 INTERNATIONALER RECHERCIIENBERICHT Intr. .,nh~es Actnzechn PCT/EP 95/02531 Im Rechcrchcnbericht Datum ce Mitglicdcer) der Datum der angefidhrtes Patcntdokument Verdffentlichn Paten tfamilie Veraffentlichung EP-A-0321088 21-06-89 AU-B- 2645488 08-06-89 CA-A- 1333313 29-11-94 DED 8785 1-39 DE-T- 3887485 0-03-94 E-T- 308878 08-09-94 JPE-T- 200668 16-012-94 JP-B- 6018851 16-03-94 US-A- 4952456 28-08-90 US-A-4568735 04-02-86 KEINE WO-A-8604902 28-08-86 US-A- 4579887 01-04-86 AU-B- 567631 26-11-87 AU-B- 5514386 10-09-86 CA-A- 1250068 14-02-89 EP-A,B 0214231 18-03-87 JP-T- 62500035 08-01-87 WO-A-9304104 04-03-93 AU-A- 2507292 16-03-93 CA-A- 2114795 04-03-93 EP-A- 0601069 15-06-94 JP-T- 6510079 10-11-94 NO-A- 940656 25-04-94 t NZ-A- 244069 27-04-95 Foni*Iatt PCrjIIA1218 (ANUang Pttantfamnlia)(Jul 1992)