WO1995019387A1

WO1995019387A1 - Plastisol composition

Info

Publication number: WO1995019387A1
Application number: PCT/EP1995/000010
Authority: WO
Inventors: Randolf Karrer; Michel Collet; Jean-Claude Abel
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 1994-01-12
Filing date: 1995-01-03
Publication date: 1995-07-20
Also published as: ZA95179B; EP0739375A1; DE4400509A1; TR28973A

Abstract

The addition of secondary bonding agents in the form of trivalent or higher aliphatic alcohols and/or alkanol amines to PVC plastisols improves the bonding properties, especially on cataphoretically coated sheet metals. Here it is possible to reduce the polyamino amides used as primary bonding agents to a minimum and there is no need to add expensive blocked polyurethanes. These PVC plastisols can be used in the automobile industry as adhesives, sealants and undersealing coatings and exhibit excellent adhesion even after varied climatic testing with very damp conditions.

Description

PRIMARE AND SECONDARY ADMINISTRATORS INCLUDING PLASTISOL COMPOSITION

The invention relates to plastisol compositions which contain secondary adhesion promoters in addition to the primary adhesion promoters, a process for their preparation and their use.

Plastisols are generally understood to mean dispersions of organic plastics in plasticizers which gel when heated to a higher temperature and harden when cooled. The plastisols most widespread in practice today contain predominantly fine-powdered polyvinyl chloride, copolymers of vinyl chloride, more recently also methacrylate copolymers or styrene copolymers. These fine powdered polymers are dispersed in a liquid plasticizer and form a paste. Such plastisols are used for a wide variety of purposes. In the automotive industry, plastisols are used for underbody protection, for seam sealing and sealing, for lining the hood or as an adhesive. Depending on the application, these plastisols contain, in addition to the finely divided polymer powders and the liquid plasticizers, other additives. Such additives are fillers, adhesion promoters, stabilizers, rheology aids and water-absorbing substances.

Adhesion promoters are added to the plastisols to ensure long-term adhesion of the plastisols to steel or galvanized, to effect tin-plated or electro-coated sheets. Basic compounds such as polyaminoamides are predominantly used as adhesion promoters for PVC plastisols. In the case of plastisols based on methyl methacrylate copolymers, these copolymers often contain as an adhesion-promoting comonomer vinylimidazole, and the plastisol based on styrene copolymers contain an olefinically unsaturated carboxylic acid as comonomer as an adhesion-promoting component; however, both types of plastisol can optionally also contain polyaminoamides Adhesion promoter component are added. Phenolic resins or terpene-phenolic resins or also radical-polymerizing monomers or oligomers, such as, for example, trimethylolpropane acrylate or methacrylate, butanediol di (meth) acrylate with radical initiators, are occasionally used as adhesion promoters in plastisols. Furthermore, epoxy compounds or polyurethane derivatives in blocked or microencapsulated or also in unblocked form are frequently added to the plastisols as adhesion promoters.

The purpose of these adhesion promoters, hereinafter referred to as primary adhesion promoters, is to ensure the long-term adhesion of the plastisols on the substrate, in particular also after exposure to moisture or climatic changes over a long period of time.

In the automotive industry, the plastisols are usually gelled simultaneously with the layers of paint in the stoving ovens provided for this purpose. However, modern automotive coatings require increasingly lower temperatures for this baking process, so that the plastisols also have to be gelled at these low baking temperatures. Apart from the electrocoat, these baking temperatures are between about 100 ° C and 150 ° C. As a result, the demands on the adhesion promoter system of the plastisols increase, so that today mainly polyamino amides and / or polyurethane systems, possibly in blocked form Shape, are used. The use of polyaminoamides as an adhesion promoter additive in plastisols is known and is described, for example, in DE-A-2654871. Further special embodiments of the polyaminoamides as adhesion promoters are described in the following patent applications: DE-A-3201265, DE-A-3221354 and DE-C-3111815.

The use of blocked polyurethane systems as an adhesion promoter in plastisol compositions is e.g. in US-A-5043379, JP-A-1289854, DE-A-3920325 or EP-A-214495.

Although the adhesion promoter systems based on blocked polyurethanes significantly improve the adhesive strength of plastisols, in particular after severe climatic changes, it is desirable to dispense with these expensive components for reasons of cost. However, weakness in adhesion is very often observed in plastisol compositions which do not contain (blocked) polyurethane systems as additional adhesion promoters. These ^" weaknesses ^" occur particularly clearly when the plastisol has to adhere to a variety of different bases, or when one type of PVC has to be replaced by another for logistical reasons.

Furthermore, this weakness in adhesion is also very frequently observed in plastisol compositions which contain so-called hollow microspheres in order to reduce the specific weight. It is very often found that even high additions of polyaminoamides do not significantly improve the adhesion. So far, it has been managed to optimize the plastisol formulation for the respective substrate or to optimize it again when replacing the PVC type. For plastisol compositions containing hollow microspheres, the RD-349057-A proposes the use of polyaminoamides as adhesion promoters which contain triethylene tetra in. This procedure is only recommended in a few cases, since it is known from DE-A-4112823 that strongly basic compounds such as polyaines interact with constituents from the electrocoat materials, in particular cathodic electrocoat materials, with the time for yellowing of paints can lead. This yellowing problem primarily affects light, pastel-colored and white lacquers which are applied to the plastisols, since the discoloration is more easily noticed, especially if these lacquers are applied to the plastisol without an intermediate lacquer (filler).

The object was therefore to find inexpensive additives for plastisol compositions which act as secondary adhesion promoters in such a way that the influence of the substrate, in particular the electrocoat, is reduced on the adhesive behavior of the plastisol composition. In addition, the invention was based on the object of reducing the influence of the PVC type used on the adhesive behavior of the plastisol composition.

This object was achieved according to the invention in that, in addition to the primary adhesion promoters, small amounts of secondary adhesion promoters are added to the plastisol composition. Trivalent or higher aliphatic alcohols and / or alkanols are suitable as secondary adhesion promoters. Glycerol, trimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythritol, pentite, pentose, hexite or hexose are particularly suitable as trihydric or higher aliphatic alcohols. Suitable alkanolamines can be selected from the group ethanolan, diethanolamine, triethanolamine, mono- or dialkylethanolamine, propanolamine, dipropanolamine, tripropanolamine, mono- or dialkyl derivatives of ethanolamine or propanola ins or monoalkyl derivatives of diethanolamine or dipropanolamine to be selected.

The secondary adhesion promoters according to the invention act even in very low concentrations of 0.01% by weight to about 5% by weight, preferably in concentrations of 0.1% by weight to 1.5% by weight, based on the total composition of the plastisol used. Surprisingly, it is found that the plastisols according to the invention have very good adhesion to a large number of electrocoat materials, regardless of the stoving cycle and the PVC type used. In particular, this good adhesion is maintained even after long climate change tests, e.g. the so-called "cataplasma test" observed. This cataplase test is intended to simulate the aging behavior of the substrates to be examined. Further details of this climate change test are described in the examples.

In addition to the secondary adhesion promoters according to the invention, the plastisols according to the invention can contain further customary additives. All conventional organic plasticizers customary in plastisol technology are suitable as plasticizers (cf. Paul E. Bruins, Plasticizer Technology (Weinhold Publ. Corp., New York), Volume 1, pages 228-232). Alkyl phthalates such as dibutyl phthalate, dioctyl phthalate, benzobutyl phthalate, dibenzyl phthalate or diisononyl phthalate are preferably used, but the known plasticizers from the group of organic phosphates, adipates and sebazates or also benzyl benzoate or dibenzyl toluene are also suitable.

All customary fillers, such as calcium carbonate in the form of various chalks, heavy latex, mica, vermiculite, pigments such as titanium dioxide, carbon black, iron oxides, can be used as fillers. The plastisols can furthermore contain the usual anti-aging agents, rheology aids such as, for example, pyrogenic silicas, bentones, and castor oil derivatives. For the production of Fish-like plastisols can also be used with so-called hollow microspheres. In addition, blowing agents can optionally be added to the plastisols if these are to be foamed during the gelling process.

Polyamino amides are preferably used as the primary adhesion promoter. These polyaminoamides and their use as adhesion promoters in plastisols are known per se, see e.g. the patent applications cited above. What is new and surprising is the reinforcing effect of the secondary adhesion promoters on the polyaminoamides and the adhesive behavior of the plastisols. The adhesion of the plastisols is improved so far, even when using very different types of PVC and on a wide variety of electrocoats, that the addition of the expensive blocked, microencapsulated or non-blocked polyurethanes is generally not necessary as an adhesion promoter. In addition, the plastisol formulations according to the invention can be used much more universally, which significantly reduces the development and testing effort.

The plastisols according to the invention are particularly well suited for use on metallic substrates in painted or unpainted form, in particular in automobile construction. In automobile construction, the plastisols according to the invention are used as underbody protection agents and as adhesives for relining the hood, as masses for sill protection and as spot welding pastes and for other adhesive applications. They can also be used to seal and seal welding or flared seams and as acoustically effective coatings.

The following examples are intended to explain the invention in more detail. As any person skilled in the art can see, the examples are intended to show the influence of clarify individual parameters to the present invention, but they do not represent a limitation of the inventive concept.

Examples:

In the examples listed below, the cured plastisol formulations are preferably adhered to by tensile shear strength tests. For this purpose, steel sheets, 100 mm x 25 mm x 1 mm, are bonded with an overlapping adhesive joint made of plastisol of 25 mm x 10 mm x 2 mm. Apart from the phosphating and the cataphoretic paint coating, the sheets do not receive any pretreatment. The cataphoretic varnish was either burned in the so-called •• Mini "heating cycle (155 ° C-170 ° C) or in the so-called" Maxi "heating cycle (165 ° -200 ° C). After application of the plastisol the overlapping test specimens were optionally subjected to a so-called "mini" hardening cycle (30 min., 140 ° C.- 145 ° C.) or a so-called "maxi" hardening cycle (60 min., 160 ° C.-165 ° C.) The tensile shear strength test was then carried out at room temperature at a tear speed of 10 mm / min. The tensile shear strength values are given in MPa.

For the so-called "cataplasma" test, the glued and hardened test specimens were each wrapped with 40 g of cotton wool, which was soaked in 400 ml of demineralized water. The test specimens pretreated in this way were sealed in a polyethylene bag and then stored at 70 ° C. for 7 or 14 days. This was followed by storage at -20 ° C. for two hours, followed by air conditioning at room temperature for at least one hour and at most four hours, which was immediately followed by the tensile shear strength test. Example 1 :

The following ingredients were mixed in an intensive mixer to form a homogeneous, stable paste:

Dioctyl adipate 4.02 parts diisoheptyl phthalate 25.62 parts extender PVC (Solvig 266 SF (RTM)) 4.02 parts paste PVC (Evipol EP 7099 (RTM)) 20.32 parts ground chalk, average particle diameter 4.5 μm 25.53 parts chalk, medium. Particle diameter 0.07 μm 14.34 parts pyrrogenic silica (Aerosil 200 (RTM)) 1.1 parts gasoline, boiling range 65-95 ° C 0.53 parts polyaminoamide (Euretec 505 (RTM)) 1.2 parts calcium oxide 2 , 01 parts color pigment from titanium dioxide and carbon black 1.31 parts.

Example 2:

A plastisol was produced in the same way as described in Example 1, but the paste PVC was replaced by Vestolit 7031 (RTM).

Example 3:

0.3% by weight of glycerol was homogeneously mixed into a plastisol from Example 2.

Example 4:

0.1% by weight of diethanolamine was homogeneously mixed into a plastisol from Example 2.

Tensile shear strength tests were carried out on cataphoretically coated sheets (type 71896M from Renault) carried out. For this purpose, the test specimens were prepared as described in the introduction and subjected to the tensile shear strength test either immediately after curing and cooling or after a 7-day cataplasma test (CATA 7) or a 14-day cataplasma test (CATA 14). The test results of Examples 1 to 4 are summarized in Table 1 below, the first temperature in the heating cycles relating to the stoving temperature of the cataphoresis coating and the second temperature to the curing of the plastisol adhesive . The fracture pattern was assessed visually, in the table C means an exclusively cohesive fracture, i.e. a fracture within the adhesive joint, A means an adhesive fracture on the substrate surface, A / C mainly means adhesive fracture with a somewhat cohesive fracture pattern, C / A mainly means cohesive break with adhesive components or a break in the adhesive joint very close to the substrate surface.

As can be seen from the following Table 1, both the formulations of Example 1 and those of Example 2 found adhesive fractions in the fracture pattern in many stoving conditions, especially after cataplasmal storage. An addition of glycerol or diethanolamine according to the invention (Examples 3 and 4) generally leads not only to a higher tensile shear strength, even after storage in cataplas, but also to exclusively cohesive fracture patterns.

Example 5

An underbody protection formulation was prepared analogously to Example 1, but this contained a total of 34.63% by weight PVC consisting of a paste PVC, an extender PVC and a vinyl acetate copolymer. This formulation additionally contained hollow plastic microspheres in an amount of 0.5% by weight. The formulation contained 1.0% by weight of polyaminoamide (Euretek 505) as an adhesion promoter.

Example 6

An underbody protection formulation was prepared as described in Example 5, but this formulation contained two% by weight of the polyamino amide as an adhesion promoter.

Example 7

An underbody protection formulation was prepared analogously to Example 5, but this contained 1% by weight of polyaminoamide and an additional 2.4% by weight of a blocked polyurethane adhesion promoter.

Example 8

0.3% by weight of glycerin was added to an underbody protection formulation of Example 5.

Example 9

0.3% by weight of triethanolamine was added to an underbody protection formulation of Example 5.

The tensile shear strength values (initial values) are in the summarized below in Table 2, the substrate used was the cataphoretic coating 742962M (Peugeot). As can be seen from the results in Table 2, an unsatisfactory fracture pattern is observed on this cataphoresis coating in many heating cycles with the formulation according to the prior art (Example 5); this is also due to increased proportions of polyaminoamide as adhesion promoter (Example 6) or blocked polyurethane systems (Example 7) were not significantly improved. Examples 8 and in particular Example 9 according to the invention clearly show that the addition of polyhydric alcohols or alkanolamines according to the invention also significantly improves the fracture pattern in this formulation.

Table 2

1 1

| Example 5 6 7 8 9 |

| Heating

| cyclen

| 170 ° C / 140 ^β C 2.8 3.1 3.7 2.6 2.9 |

| 170 ° C / 140 ° C C / A C / A C / A C c |

| 170 ° C / 160 ° C 4.9 5.2 5.0 4.2 4.5 |

| 170 ° C / 160 ° C C / A C / A C / A C c |

| 200 ° C / 140 ° C 2.8 3.0 3.5 2.7 3.3 |

| 200 ° C / 140 ° C A / C C / A C / A A / C c |

| 200 ° C / 160 ° C 4.9 4.9 4.6 4.2 4.5 |

| 200 ° C / 160 ° CC / ACC / AC c | In the examples described above, the adhesive properties were determined exclusively by tensile shear strength tests. In the case of rapid practical tests, the adhesion is often assessed by means of a peeling test, the plastisol being applied in a bead to the substrate to be tested, and the bead and the substrate are then subjected to the intended curing conditions. After the test specimen has cooled to room temperature, the caterpillar is cut into a piece with a sharp knife near the substrate interface and then peeled off by hand, the fracture pattern being assessed visually.

In these tests, too, the plastisol compositions according to the invention showed only cohesive fracture patterns, while the formulations of the prior art, in a manner similar to the tensile shear strength tests, have high adhesive fractions.

The additives of secondary adhesion promoters according to the invention also had an effect when using a large number of further PVC types, both paste types and extender types and also vinyl acetate copolymers.

Similar favorable adhesion properties were observed on a large number of other cataphoresis substrates.

Claims

P a t e n t a n s r u c h e

l.) plastisol, characterized in that it contains secondary adhesion promoters in addition to primary adhesion promoters.

2.) plastisol according to claim 1, characterized in that the secondary coupling agents are trihydric or higher aliphatic alcohols and / or alkanolamines.

3.) plastisol according to claim 2, characterized in that the molecular weight of the secondary adhesion promoter is less than or equal to 500.

4.) plastisol according to claim 1 to 3, characterized gekenn¬ characterized in that the secondary adhesion promoter in concentrations from 0.01 wt.% To 5 wt.%, Preferably from 0.1 wt.% To 1.5 wt.%, Based on the total addition composition are included.

5.) plastisol according to claim 1 bis, characterized gekenn¬ characterized in that the aliphatic alcohols are selected from the group glycerol, trimethylolpropane, trimethylolethane, pentaerythritol, dipentaerythritol, pentites, pentoses, hexites or hexoses.

6.) plastisol according to claim 1 to 4, characterized gekenn¬ characterized in that the alkanolamines from the group ethanolamine, diethanolamine, triethanolamine, mono- or dialkylethanolamine, alkyltriethanolamine, propanol in, dipropanolamine, tripropanolamine or the mono- or dialkyl derivatives of propanolamine or Dipropanolamines can be selected.

7.) plastisol according to one of claims 1 to 6, characterized in that the plastisol contains further customary additives.

8.) Process for the production of plastisols according to at least one of claims 1 to 7, characterized in that the secondary adhesion promoter is mixed separately at the end of the mixing process, if necessary even subsequently, into the plastisol composition.

9.) Process for the production of plastisols according to at least one of claims 1 to 7, characterized in that the secondary adhesion promoter is mixed into the plastisol composition together with the other adhesion promoters or other additives, or that the individual additives are mixed with the plastisol composition prior to mixing the plasticizer and possibly fillers and / or pigments are pasted and the plastisol composition is mixed in as a paste.

10.) Use of plastisols according to at least one of claims 1 to 9 as underbody protection, seam sealing, adhesive, hood relining agent or sill protection in automobile construction.