WO2004018543A2

WO2004018543A2 - Rheology-improving adhesion promoters for pvc plastisols

Info

Publication number: WO2004018543A2
Application number: PCT/EP2003/050381
Authority: WO
Inventors: Jörg Volle; Christa Broll; Alfred Kruse
Original assignee: Huntsman Advanced Materials Switzerland GmbH; Vantico GmbH
Current assignee: Huntsman Advanced Materials Switzerland GmbH
Priority date: 2002-08-21
Filing date: 2003-08-18
Publication date: 2004-03-04
Anticipated expiration: 2005-02-21
Also published as: WO2004018543A3; TW200415179A; AU2003268943A1

Abstract

Polyaminoamide resins as adhesion promoters for plastisols, in particular PVC plastisols, obtainable by condensation of a polymerized fatty acid a1) and, where appropriate, of a dicarboxylic acid a2) with a polyalkylene polyamine b) and with an amine compound c) containing hydroxy groups, a process for the preparation of these adhesion promoters, a process for improving the rheological properties of plastisols by concomitant use of these adhesion promoters, and plastisols, comprising the adhesion promoters of the invention.

Description

Rheoloqy-improving adhesion promoters for PVC plastisols

The invention relates to specific polyaminoamide resins as adhesion promoters for plastisols, in particular PVC plastisols, to a process for the production of these adhesion promoters, to a process for improving the rheological properties of plastisols, characterized in that these adhesion promoters are used concomitantly, and to plastisols comprising these adhesion promoters.

Plastisols are widely used for protecting metallic surfaces from corrosion. In particular in the automotive sector, plastisols are used for the waterproofing, bonding and sealing of seams and joints, and for protecting external surfaces, such as underbodies and sills.

These applications mostly use plastisols based on PVC polymers or on PVC copolymers. These plastisols are composed of fine polymer particles which have been dispersed in a non-volatile plasticizer. At room temperature, the polymer particles are insoluble in the liquid phase. At a higher temperature (gelling temperature), the polymer particles dissolve in the plasticizer. On cooling, the homogeneous solution hardens to give a flexible or rigid coating. The main methods used to apply these coatings to the materials to be protected are brushing, rolling, or spraying.

The formulation of plasticized polyvinyl chloride coating compositions (plastisols), and their preparation and use is extensively described in: Kre eler / Wick, Kunststoff-Handbuch [Plastics Handbook] (1963), Volume II, Part 1 , pp. 396 ff.

A significant criterion for the quality of plastisols applied in this way is their adhesion to the coated material. Relatively low adhesion of the protective layer increases the risk of penetration of aggressive fluids. For example, water can migrate under the coating and corrode the metal.

This becomes increasingly possible as the adhesion of the protective film to the metal becomes lower. To increase the adhesion of these coatings, therefore, industry adds adhesion-improving additives to the plasticized polyvinyl chloride. The function of the adhesion promoters is to bring about lasting adhesion to the surfaces of commonly encountered materials, such as non-degreased untreated steel, galvanised metal sheet or tin-coated metal sheet, electrocoated metal sheet, etc.

There has been no lack of previous attempts to provide suitable adhesion promoters which can give sufficiently good adhesion of the plastisol on the work piece to be coated. Examples of these adhesion promoters are polyamines, epoxy resins, capped isocyanates, organofunctional silanes, and esters of acrylic or methacrylic acid.

However, these products often have shortcomings, e.g. adhesion which is still not adequate, or insufficiently stable plastisol viscosity. In many instances, these additives are also active only when relatively high concentrations have been reached, and there are therefore doubts about their cost-effectiveness. In addition, a disadvantage of free polyamines is that white, pale, or pastel-coloured coatings discolour markedly during stoving, or over the course of time. The discolouration is generally attributed to amines, small amounts of which migrate to the surface of the coating, where oxidative processes convert them into colorant substances. For this reason, the adhesion promoters used in most instances comprise polyaminoamides containing imidazoline groups. These also have good adhesion to the substrate, even at relatively low concentrations in the plastisol. These adhesion promoters are described by way of example in DE 26 54 871 A1 and DE 32 01 265 A1. These describe adhesion promoters based on polyaminoamides containing imidazoline groups, or, respectively, post- condensates of these polyaminoamides, which have to have a high proportion of trimeric fatty acids and of fatty acids with a higher degree of polymerization, and have to have a high imidazoline content, and are thus intended to give good adhesion results. The imidazoline groups are formed here at relatively high temperatures of from about 160 to 280°C by intramolecular cyclization with elimination of water from the amide groups.

However, the usual amounts used of these adhesion promoters, from 0.5 - 2% (see, for example, DE 26 54 871 A1), have a severe adverse effect on the rheology of the plastisol. In particular, the enormous reduction in the yield points has a disadvantageous effect in application of the plastisols. In practice, that means a loss of stability of the PVC plastisol after application via nozzles or extruders. This is particularly disadvantageous if the PVC plasitol is applied to vertical surfaces, the result being a tendency for the PVC plastisol to flow downward. In practice, this can be countered by adding expensive fillers and costly thixotropicizing agents, but this leads to an increase in the cost of the PVC formulation. Another problem is that the use of thixotropicizing agents adversely affects the adhesion of the plastisol.

DE 44 00 509 A1 describes adhesion promoters for PVC plastisols which comprise, besides a polyaminoamide as primary adhesion promoter, trihydric or higher-functionality alcohols and/or alkanolamines with a molecular weight <= 500, as secondary adhesion promoters. Although, when comparison is made with the conventional polyaminoamides, the addition of these secondary adhesion promoters somewhat reduces the impairment of rheology properties of the plastisol, adhesion falls markedly when the adhesion promoters are used in the amounts usual for plastisols, about 1%.

It is therefore an object of the invention to provide adhesion promoters which permit a high level of adhesion to the substrate, and which have low viscosity, and are therefore easy to process, and which have only a slight effect on the rheology properties of the plastisol, so as to reduce the amount of expensive fillers and costly thixotropicizing agents used, or so as to make their use completely unnecessary. At the same time, it is intended that there is no increase in the proportion of the adhesion promoter in the PVC plastisol.

This object is achieved by way of the adhesion promoters of the invention.

The present invention therefore provides the use of specific polyaminoamide resins which are obtainable via condensation of a1) polymerized fatty acids, where appropriate with concomitant use of a2) dicarboxylic acids, with b) polyalkylene polyamines, and c) amine compounds containing hydroxy groups, or else adducts of these condensation products with epoxy compounds, as adhesion promoters for plastisols.

Surprisingly, it has been found that the use of these polyaminoamides in plastisols brings about high adhesion to the substrate, and that at the same time the rheology properties of the plastisol are significantly less affected than is the case with the polyaminoamide adhesion promoters usually used. The polyaminoamides of the invention have comparatively low viscosity. There is very little discolouration of the plastisol during stoving.

The polyaminoamides of the invention are obtainable from a1) polymerized fatty acids, and, where appropriate, a2) dicarboxylic acids, b) polyalkylene polyamines, and c) amine compounds containing hydroxy groups, by polycondensation, as described below. The expression polymerized fatty acids encompasses polymerized fatty acids which are prepared from unsaturated, naturally occurring or synthetic, monobasic, aliphatic acids having from 12 to 22 carbon atoms, preferably 18 carbon atoms. The fatty acids may be polymerized by a well-known process (see, for example, a process in DE 25 06 211 A1).

According to the invention, the condensation uses from 0.5 to 1.0 equivalent of a polymerized fatty acid a1), from 0.0 to 0.5 equivalent of a dicarboxylic acid a2), from 0.2 to 1 mol of a polyalkylene polyamine b), and from 0.05 to 0.8 mol of an amine compound c) containing hydroxy groups, the sum of the equivalents from a1) and a2) being one equivalent.

The equivalents of the polymerized acids or of the dicarboxylic acids here are the molecular weight equivalent to one acid group. In the case of a difunctional acid, this would be half of the molecular weight, and in the case of a trifunctional acid it would be one third of the molecular weight, etc.

Polymerized fatty acids a1) whose use is preferred are commercially available products which have approximately the following composition: monomeric acids: from 0.1 to 10%; dimeric acids: from 20 to 98%; trimeric acids and acids with a higher degree of polymerization: from 0.1 to 80%.

These fatty acids are obtainable from the company Unichema with the trade mark Pripol^® According to the invention, particular preference is given to polymeric fatty acids with a proportion of not more than 50% of trimeric acids and acids with a higher level of polymerization, examples being Pripol 1017, with the following composition: monomeric acids: not more than from 1 to 3%; dimeric acids: not less than from 75 to 82%; trimeric acids and acids with a higher degree of polymerization: not more than from 18 to 21 %.

Dicarboxylic acids a2) which may be used are: saturated or unsaturated, straight-chain or branched, aliphatic or cycloaliphatic acids which have not more than 20 carbon atoms, for example: oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, primelic acid, suberic acid, azelaic acid, sebacic acid, trimethyladipic acid, maleic acid, and fumaric acid, hexahydrophthalic acid, tetrahydrophthalic acid; or aromatic dicarboxylic acids, for example phthalic acid, isophthalic acid, terephthalic acid. Preference is given to the use of aliphatic dicarboxylic acids. The dicarboxylic acids may be used individually or in a mixture. These dicarboxylic acids a2) are preferably used in a mixture with the polymerized fatty acids a1) described above. It is also possible to add small amounts of tricarboxylic acids, e.g. trimesic acid.

The amine compounds c) containing hydroxy groups and used according to the invention are those which have at least one primary amino group for subsequent reaction with the acid groups of the carboxylic acids. Examples which may be mentioned are: monoalkanolamines, e.g. ethanolamine, propanolamine etc.; mono,- di,- and polyalkanol polyamines e.g. hydroxyethylethylenediamine (aminoethylethanolamine), hydroxypropylethylenediamine (aminoethylpropanolamine), hydroxyethyltriethylenetetramine, hydroxypropyltriethylenetetramine, di(hydroxyethyl)triethylenetetamine, di(hydroxypropyl)triethylenetetramine, etc.; glycolamines, e.g. diglycolamine.

According to the invention, it is preferable to use monoalkanolamines, in particular ethanolamine and hydroxyethyltriethylenediamine. Clearly, those amine compounds containing hydroxy groups listed in the previous paragraph are merely a small selection from the amine compounds which may be used according to the invention.

Preferred polyalkylene polyamines b) for preparing the polyaminoamides are polyethylene polyamines.

Particular preference is given here to polyethylene polyamines having at least 4 nitrogen atoms in the molecule.

The polyaminoamides of the invention may also be subjected to a downstream addition reaction with epoxy compounds. The invention therefore also provides adducts of the inventive polyaminoamides described above with epoxy compounds, obtainable by reacting a polyaminoamide of the invention with an epoxy compound.

In essence, any of the products having one or more than one epoxy group per molecule may be used as epoxy compound. A comprehensive list of these epoxy compounds is found by way of example in the handbook "Epoxidverbindungen und Epoxidharze" [Expoxy Compounds and Epoxy Resins] by A.M. Paquin, Springer Verlag, Berlin, 1958 and in "Handbook of Epoxy Resins", 1967, Chapter 2, pp. 257-307.

A preferred epoxy compound is kresyl glycidyl ether.

The proportion of the epoxy component in the polyaminoamide adduct may, depending on the nature of the epoxy compound and on the desired product properties, be from 0.1 to 30%, preferably from 2 to 10% (by weight), so as to retain good processability of the polyaminoamide adduct used as adhesion promoter.

The inventive polyaminoamides or their adducts may also be used after solution in plasticizers and/or solvents. Examples of plasticizers/solvents which may be used are phthalic esters, e.g. dibutyl phthalate, dioctyl phthalate, diisononyl phthalate, and benzyl alcohol.

This invention also provides a process for preparing the adhesion promoters of the invention, characterized in that a polymerized fatty acid a1), and, where appropriate, a dicarboxylic acid a2), is added to an initial charge of a polyalkylene polyamine b) and to an amine compound c) containing hydroxy groups, and water is distilled off after heating at up to 230°C, where appropriate in vacuo.

However, the adhesion promoters of the invention may also be obtained by multistage processes, for example those described in DE 694 02 959 T2.

The invention also provides the use of the adhesion promoters of the invention for plastisols, in particular PVC plastisols.

When the adhesion promoters of the invention are used, there is comparatively little effect on the rheological properties of the plastisol, there being an overall improvement in those properties. The invention therefore also provides a process for improving the rheological properties of plastisols, in particular of PVC plastisols, characterized in that use or concomitant use is made of an adhesion promoter of the invention, and a process for producing coatings and adhesive bonds for materials, by applying plastisols based on fine- particle polyvinyl chloride or, respectively, vinyl chloride copolymers, comprising conventional fillers, additives, plasticizers and adhesion promoters, characterized in that use is made of an adhesive promoter of the invention.

The adhesion promoters of the invention are added in proportions of from 0.3 to 5% by weight, preferably from 0.5 to 2% by weight, particularly preferably 1 % by weight based on the weight of the plastisol, and homogenized, and the plastisols thus prepared are stoved on the material at temperatures of at least 90°C, preferably from 120 to 160°C.

The invention also provides plastisols for the production of coatings on materials, comprising fine-particle polyvinyl chloride or, respectively, vinyl chloride copolymers, conventional plasticizers, fillers, additives and adhesion promoters, characterized in that an adhesion promoter of the invention is used.

Examples

Preparation of inventive polyaminoamides: Example 1 :

290 g of Pripol 1017 = 1 equivalent is fed within about 30 min at from 60°C to 90°C into a mixture of 30.8 g (0.163 mol) of tetraethylenepentamine, 21 g of N-aminoethylpiperazine (0.163 mol), 48.8 g of ethyleneamine 100 ^*> (0.163 mol), and 33.8 g of aminoethylethanolamine (0.325 mol). The product mixture is heated to 220°C and stirred at this temperature for 2 hours, while the water produced in the reaction is distilled off. The mixture is then cooled to 175°C, and a vacuum is applied (25 mbar) and maintained for 1 hour. The product is then allowed to cool. The amount of distillate is 21.9 g. ^Λ) = polyethylene polyamine with a molar mass of about 300 g/mol

Example 2:

Using the preparation method of example 1 , 290 g of Pripol 1017 (1 equivalent),

150 g of ethyleneamine 100 (0.5 mol) and 31.2 g of aminoethylethanolamine (0.3 mol) are condensed. Distillate: 25 g.

Example 3:

97.5 g of ethyleneamine 100 (0.325 mol), 21.0 g of N-aminoethylpiperazine (0.163 mol) and

33.8 g of aminoethylethanolamine (0.325 mol) are condensed. Distillate: 24 g. Example 4:

73 g of triethylenetetramine (0.5 mol) and 18 g of ethanolamine (0.3 mol) are condensed.

Distillate: 21 g.

Example 5:

Using the preparation method of example 1 , 145 g of Pripol 1017 (0.5 equivalent),

51 g of sebacic acid (0.5 equivalent), 21 g of N-aminoethylpiperazine (0.163 mol),

97.5 g of ethyleneamine 100 (0.325 mol), and 33.8 g of aminoethylethanolamine (0.325 mol) are condensed. Distillate: 26.4 g.

Example 6:

Using the preparation method of example 1 , 145 g of Pripol 1017 (0.5 equivalent), 36.5 g of adipic acid (0.5 equivalent), 21 g of N-aminoethylpiperazine, 97.5 g of ethyleneamine 100 (0.325 mol), and 33.8 g of aminoethylethanolamine (0.325 mol) are condensed. Distillate: 26.8 g.

Preparation of polvaminoamide-epoxide adducts:

The adducts are prepared by using the polyaminoamide as initial charge and heating this at from about 70°C to 80°C, and adding an epoxy compound dropwise within about 60 min. Stirring is then continued for about 30 min until the reaction is complete.

Example 7:

100 g of the polyaminoamide from example 2 are subjected to an addition reaction with 5 g of kresyl glycidyl ether.

Example 8:

Comparative example for example 2: the alkanolamine (0.3 mol) used in ex. 2 is replaced by ethyleneamine 100 (0.3 mol). Using the preparation method of example 1 , 290 g of Pripol 1017 (1 equivalent) and 240 g of ethyleneamine 100 are condensed. Distillate: 27 g.

Example 9: Comparative example: Euretek^® 563 (commercial adhesion promoter based on a polyaminoamide from the company Vantico GmbH).

Example 10:

Comparative example: 80 parts by weight of the adhesion promoter from example 9

(Euretek 563) are homogenised at about 80°C with 20 parts by weight of aminoethylethanolamine.

Usage examples:

Preparation of plastisols:

1%, based on the entire mixture, of the abovementioned polyaminoamides is added as adhesion promoter to a plastisol composed of: 35% of diisononyl phthalate, 25% of paste

PVC (e.g.: Solvic^® 347 MB), 16.0% of coated chalk (Socal^® 312), 16.5% of naturally occurring chalk (Juraperle), 2.0% of CaO, 0.2% of ZnO, and 4.3% of Exxsol^® 80.

However, the adhesion promoters of the invention may be added to conventional plastisol formulations other than the formulations given above, in order to obtain the self-adhesive plastisols of the invention.

The adhesion achievable using the plastisols of the invention is determined manually. For this, use is made of Cathoguard 400 CEC sheets from the company BASF. Dimensions of adherends 25 x 100 mm.

Method:

A spatula is used to apply a strip of the PVC plastisol, about 1.5 cm width and about 5 cm in length, to the CEC strip, and a doctor is used to spread the plastisol to give a test strip of width 1.5 cm with a thickness of 1.5 mm. The test specimen is placed in the temperature- controlled drying cabinet and stoved at 140°C for 30 minutes. After stoving, the test specimen is removed from the drying cabinet. After cooling (for at least 2 hours), the adhesion test can be carried out. For this, a knife is used to make an incision to a width of about 0.5 cm in both sides of the test strip. The test strip is then tested manually for peelability. The following classification system is used for assessment:

No adhesion at all

O Strip can easily be peeled; slight film of plastisol remaining on the CEC layer

Θ Strip difficult to peel; slight film of plastisol remaining on the CEC layer

Strip difficult to peel and breaks on peeling; significant film of plastisol remaining on the CEC layer

++ Strip cannot be peeled

The yield points (Pa) of the plastisols were determined to DIN 53019, using the Viscolab SM rotary viscosi meter with the Rheolab-Electronic MC 10, measurement system Z4, at a shear rate of up to 700/s. High yield points here mean advantageous run-off behaviour. The characteristics of the polyaminoamides obtained and their adducts, and also the results, are listed in table 1 below.

Table 1 :

Viscosities were determined using a VT 550 Haake rotary viscosimeter, and following the manufacturer's instructions. Interpretation of results:

As can be seen from the table, the adhesion of the plastisols which comprise an adhesion promoter of the invention is very good. The use of the adhesion promoters of the invention has markedly less effect on the rheology properties of the plastisol than is the case when the adhesion promoters of the comparative examples are used. The effect of the adhesion promoters of the invention is in particular apparent on comparing examples 2, 8 and 10. Although the fall-off in yield point is not as marked as usual when using the adhesion promoter of example 10, where a free alkanolamine was added, there is nevertheless a significant reduction in the adhesion of the plastisol. Use of the polyaminoamide of example 8, with molar replacement of the alkanolamine by a polyethylene polyamine, again leads to a marked fall-off in yield point. The use of a commercial adhesion promoter, as in example 9, likewise leads to a marked fall-off in yield point. Surprisingly, use of the adhesion promoters of the invention, into which alkanolamines have been incorporated, can markedly reduce the effect of the adhesion promoter on the yield point of the plastisol, while retaining excellent adhesion properties. However, if free alkanolamines are added to the adhesion promoter, but are not incorporated into the molecule, the result is a marked reduction in adhesion to the substrate. This result was not foreseeable.

Claims

Patent Claims

1) Adhesion promoter, obtainable by condensation of a1) from 0.5 to 1.0 equivalent of a polymerized fatty acid, and a2) from 0.0 to 0.5 equivalent of a dicarboxylic acid, with b) from 0.2 to 1.0 mol of a polyalkylene polyamine, and c) from 0.05 to 0.8 mol of an amine compound containing hydroxy groups, where the sum of the equivalents from a1) and a2) is 1 equivalent.

2) Adhesion promoter according to Claim 1 , characterized in that component a1) has the following composition: monomeric acids: from 0.1 to 10%; dimeric acids: from 20 - 98%; trimeric and acids with a higher degree of polymerization: from 0.1 - 80%.

3) Adhesion promoter according to Claim 1 or 2, characterized in that the dicarboxylic acid a2) used comprises a saturated or unsaturated, straight-chain or branched, aliphatic or cycloaliphatic acid having not more than 20 carbon atoms.

4) Adhesion promoter according to Claim 3, characterized in that the dicarboxylic acid a2) used comprises an aliphatic acid.

5) Adhesion promoter according to any of Claims 1 to 4, characterized in that the amine compound c) containing hydroxy groups has at least one primary amino group per molecule.

6) Adhesion promoter according to Claim 3, characterized in that component c) is ethanol amine or hydroxyethylethanolamine.

7) Adhesion promoter according to any of Claims 1 to 6, characterized in that the polyalkylene polyamine b) is a polyethylene polyamine.

8) Adhesion promoter according to any of Claims 1 to 7, characterized in that the polyethylene polyamine contains at least 4 nitrogen atoms in the molecule.

9) Adhesion promoter, characterized in that a condensation product according to any of Claims 1 to 8 is reacted with an epoxy compound. 10) Adhesion promoter according to at least one of Claims 1 to 9, characterized in that the epoxy compounds according to Claim 9 are kresyl glycidyl ether.

11) Adhesion promoter according to any of Claims 1 to 10, characterized in that the adhesion promoter has been dissolved in a solvent and/or plasticizer.

12) Process for preparing an adhesion promoter as claimed in any of Claims 1 to 11 , characterized in that a polymerized fatty acid a1), and, where appropriate, a dicarboxylic acid a2), is added to an initial charge of a polyalkylene polyamine b) and to an amine compound c) containing hydroxy groups, and water is distilled off after heating at up to 230°C, where appropriate in vacuo.

13) Use of adhesion promoters according to any of Claims 1 to 11 in plastisols, in particular in PVC plastisols.

14) Process for improving the rheological properties of plastisols, in particular of PVC plastisols, characterized in that an adhesion promoter according to any of Claims 1 to 11 is used concomitantly.

15) Process for producing coatings and adhesive bonds for materials, by applying plastisols based on fine-particle polyvinyl chloride or, respectively, vinyl chloride copolymers, comprising conventional fillers, additives, plasticizers and adhesion promoters, characterized in that use is made of an adhesion promoter according to any of Claims 1 to 11.

16) Process according to Claim 14 or 15, characterized in that the adhesion promoter is added in proportions (in % by weight) of from 0.5 to 5%, preferably from 0.5 to 2.5%, particularly preferably 1 %, based on the weight of plastisol, and homogenized, and the plastisols thus prepared are stoved on the material at temperatures of 90°C or above, preferably at from 120 to 160°C.

17) Plastisols for the production of coatings on materials, comprising fine-particle polyvinyl chloride or, respectively, vinyl chloride copolymers, conventional plasticizers, fillers, additives, characterized in that the adhesion promoter used comprises at least one product according to any of Claims 1 to 9.