DE102017100932A1 - Hydroxy-functional dendritic polymers as adhesion promoters - Google Patents

Abstract

The invention relates to a molding composition containing at least one thermoplastic and a dendrimer, wherein the dendrimer has a core, a plurality of branching generations and a periphery of functional, reactive hydroxyl groups. Furthermore, the invention relates to a molding produced therefrom, a process for its preparation and a use of the molding.

Description

Technical area

The present invention relates to a molding composition comprising at least one thermoplastic and a dendrimer, a molding produced therefrom, a process for its preparation and a use of the molding.

Thermoplastics typically have a relatively nonpolar, electrically insulating and water repellent surface with low surface energy. Therefore, the wetting of such surfaces by paints, aqueous plastic dispersions, adhesives, foams or adhesion promoters is a challenge. In order to improve the wetting of paints, aqueous polymer dispersions, adhesives or foams on thermoplastic substrates, the surface must be activated by modification. For this reason, there is a need to develop appropriate methods for improving the bondability, paintability or coating of various thermoplastic materials and molding compounds.

The current industry practice for increasing the polarity of such surfaces is by oxidizing the surfaces by flame treatment or corona treatment, which contribute to or facilitate improved adhesion. Other methods include fluorination and plasma treatment.

However, the effectiveness and durability of such methods is not satisfactory. The effect of activating or polarizing such surfaces, which causes an increase in the affinity for polar formulations, is not permanent. After a certain storage time of the treated surfaces, the surface tension is reduced again. In these cases, the surface must be re-treated prior to coating.

In the automotive industry, plastics now account for between 15 and 20 percent by weight and rising. In particular, thermoplastic parts are used as injection molded articles for the interior of automobiles, for example as instrument panels, door trim or center consoles, and bonded, laminated, painted or backfoamed.

The adhesives, paints or foams used in particular in the automotive industry are based predominantly on polyurethanes (PU, PUR), i. they are formed from a polyol or diol and a polyisocyanate as a hardener. The linking occurs by the reaction of an isocyanate group (-N = C =O) of one molecule with a hydroxyl group (-OH) of another molecule to form a urethane group (-NH-CO-O-). The thermoplastic plastic substrates must also be pretreated here first to obtain active, in particular hydroxylated surfaces, which then ensure adhesion of the adhesive / paint / foam on the plastic surface. The pretreatment thus at least briefly generates reactive groups on the substrate surface which undergo a reaction with the adhesive / paint / foam and thereby ensure sufficient adhesion. In the industrial sector, the pretreatment steps involve complex investments and often considerable space and energy requirements. In addition, the result of the pretreatment is only of limited duration here - with flaming a few hours, with plasma pretreatment a few days, depending on the ambient conditions. Furthermore, there is the danger during the pretreatment that not all areas of the usually three-dimensional molded part can be uniformly achieved or surface defects in the part are present which worsen or completely negate the pretreatment and the quality of the bonding, painting or of the foam.

State of the art

The activation problem is, as described, generally solved by oxidation of the surfaces by flame treatment or corona treatment. This pretreatment briefly generates reactive OH groups on the substrate surface which undergo reaction with the adhesive, paint or foam, thereby ensuring sufficient adhesion.

Alternatively describes WO 2007/075927 Branched polyether-modified polysiloxanes as additives for coatings that improve the hydrophilicity and the tendency to fouling of coatings. The branched polyethers are based on oxetanes, glycidol and / or alkylene oxides.

WO 2008/003470 describes the use of polyhydroxy-functional polysiloxanes in thermoplastics to improve the stain-resistant and anti-adhesive properties of the thermoplastic. The polysiloxanes are obtained via addition reactions of hydroxyoxetane derivatives.

There is therefore great interest in the development of suitable surface-activating treatment methods and / or additives in order to optimize the bonding, painting or back-foaming of plastic surfaces and moldings.

Description of the invention

The object of the present invention is therefore to provide a molding compound and a molding produced therefrom, which has an increased surface tension compared to generic moldings, which allows gluing, painting or foam backing of the molded part waiving additional surface-activating treatment methods.

This object is achieved by a molding composition according to claim 1, a molding according to claim 6 and its use according to claim 11. Furthermore, the object is achieved by a method for producing a coated, painted, foam-backed or glued molding according to claim 10.

The basic idea of the present invention is that a molding composition contains at least one thermoplastic and one dendrimer, the dendrimer having a core, a plurality of branching generations and a periphery of functional, reactive hydroxyl groups. It has surprisingly been found that the objects described above are achieved by the use of a polyhydroxy-functional dendrimer as an additive in thermoplastics or polymers, thermoplastic molding compositions. Thermoplastics and thermoplastic molding compositions to which these dendrimers are added are distinguished by increased surface tension and improved adhesiveness, weldability, paintability or foamability, in particular with PUR systems, in comparison to thermoplastics or molding compositions to which such dendrimers have not been added. On the activation measures described above can thus be advantageously dispensed with. In addition, the thermoplastics and polymeric molding compositions containing functionalized dendrimers exhibit additional properties resulting from the increase in surface tension, such as antistatic properties, and in particular adhesion promotion during bonding as well as improved elongation properties in the case of welded moldings.

The core and branches of the dendrimer are preferably formed from silicon-free compounds. Preferably, the core of the dendrimer is formed from a hyperbranched polyether polyol based on trimethylolpropane (TMP) and pentaerythritol (PEA) or derivatives thereof. These alkoxylated dendrimers are also commercially available. Particularly preferred is the use of Boltorn H20, H30 and H40 (Perstorp). Commercially, hyperbranched polymers are also available as aliphatic polyethers (Polyglycerol ^™ , from HyperPolymers GmbH) or as aliphatic polyesters under the name Boltorn ^™ (from Perstorp).

Preferably, the at least one plastic to 80 to 99.999 wt .-% and the dendrimer to 0.001 to 20 wt .-% in the molding composition. The polyhydroxy-functional dendrimers can be added to the thermoplastics in relatively small amounts. The physical properties of the original thermoplastics, for example in terms of mechanical and optical properties, weatherability and processability are not affected by the low concentrations of the dendrimer.

In the following polymeric matrix systems their wetting properties could be improved in this way: The plastic is preferably selected from acrylonitrile-butadiene-styrene (ABS), styrene-acrylonitrile (SAN), polystyrene (PS), polycarbonate (PC), polyethylene (PE) , Polypropylene (PP), polyamides (PA), polyesters (PET), or mixtures thereof.

According to the invention, a shaped body which is produced from the molding composition described above has a surface tension which is at least 1.5 mN / m above the surface tension of the dendrimer-free plastic.

In this case, the functional, reactive hydroxyl groups of the dendrimer are preferably intended for chemical, in particular covalent bonding with suitable adhesives, lacquers and / or foams.

The adhesives, lacquers and / or foams preferably have isocyanate groups which are intended for chemical bonding with the functional, reactive hydroxyl groups of the dendrimer. The used adhesives, paints or foams based on PU are formed here from a polyol or diol and a polyisocyanate as a hardener. The linking takes place by the reaction of the isocyanate group (-N = C =O) of an adhesive, lacquer or foam molecule with a hydroxyl group (-OH) of the dendrimer molecule to form a urethane group (-NH-CO-O-) ,

Preferably, the dendrimers are arranged or enriched in the molding with their functional, reactive hydroxyl groups at least partially on the surface of the molding. Increasing the surface tension of thermoplastics involves mixing small amounts of polyhydroxy-functional dendrimers with different thermoplastic materials having different crystallinities and polarities to modify the surface tension. In order to achieve the above-mentioned surface modifications, the polyhydroxy-functional dendrimers distributed in the polymeric molding compositions segregate to the surface of the thermoplastic material in order to functionalize them. The dendrimers apparently diffuse during the injection molding process and / or during cooling / demolding on the surface of the plastic molding.

• a) Vermischen mindestens eines thermoplastischen Kunststoffs mit dem Dendrimer;
• b) Aufschmelzen der Formmasse unter Druck;
• c) Extrudieren der homogenisierten Schmelze oder Spritzgießen in ein Spritzgusswerkzeug;
• d) Abkühlen, Entformen und Erwärmen des erhaltenen Formkörpers;
• e) Aufbringen einer Klebstoff-, Lack- oder Schaumschicht, wobei keine zusätzliche Aktivierung der Formkörperoberfläche erfolgt.

The process for producing a shaped body described above comprises the following steps:

• a) mixing at least one thermoplastic with the dendrimer;
• b) melting the molding composition under pressure;
• c) extruding the homogenized melt or injection molding into an injection mold;
• d) cooling, demolding and heating of the resulting molded body;
• e) applying an adhesive, paint or foam layer, wherein no additional activation of the molding surface occurs.

Thus, a direct chemical bonding of the adhesive / paint / foam to the polymer matrix of the molding is made particularly advantageous. The polymer matrix is thus incorporated into the polyurethane network.

The use of a previously described molding or a molding compound thus comprises a component, wherein the component is a coated, foam-backed or glued car, aircraft or marine accessory or a part of a car, aircraft or marine accessory, preferably a coated, foam-backed, glued or laminated interior component. In this case, there is advantageously a direct chemical bond of adhesive / paint / foam with the molding.

drawing

Hereinafter, an embodiment of the molding compound or the coated, painted, foam-backed or glued molding will be explained with reference to the drawing, without wishing to limit the invention.

Showing:

1 the molecular structure of a dendrimer; and

2 a schematic representation of the chemical crosslinking reactions between the molding and adhesive / paint / foam.

1 shows the schematic structure of a dendrimer on the example of a polyglycerol dendrimer, wherein dashed circles mark different structural regions of the dendrimer. The dendrimer has a core, a multitude of branching generations, and a periphery of functional, reactive hydroxyl groups. The core of the dendrimer is formed, for example, from a hyperbranched polyether polyol based on pentaerythritol (PEA). These alkoxylated dendrimers are also commercially available. Particularly preferred is the use of Boltorn H20, H30 and H40 (Perstorp).

2 illustrates in its lower part the chemical crosslinking reactions between the functional, reactive hydroxyl groups of the dendrimer on the surface of the molding (-OH) and the isocyanate groups of a glue, paint or foam.

The adhesives, paints or foams based on PU are in this case formed from a polyol or diol from the adhesive, lacquer or foam and a polyisocyanate as hardener.

The crosslinking in the adhesive, paint or foam is carried out by the reaction of the isocyanate group (-N = C = O) of an adhesive, paint or foam molecule with a polyol group (-OH) to form a urethane group (-NH-CO-O -), see. 2 above.

Crosslinking with the shaped body is effected by the reaction of the isocyanate group (--N =C =O) of an adhesive, lacquer or foam molecule with a hydroxyl group (--OH) of the dendrimer molecule in the shaped body surface to form a urethane group (US Pat. -NH-CO-O-), cf. 2 below.

When applying the adhesive, paint or foam layer on the molding advantageously no additional activation of the molding surface is required. After the homogenized molding material has been extruded or injection-molded into an injection-molding tool, only the cooling, demoulding and subsequent heating of the resulting molded article to which the adhesive, lacquer or foam is then subsequently applied by self-crosslinking takes place. The polymer matrix is thus integrated into the resulting polyurethane network via the dendrimers.

example

Using a test ink, the determination of the surface tension of PP and PE plates with and without incorporated dendrimer, wherein when applying the liquid either forms a film or the ink dries together to form droplets. If the liquid film stops for at least 2 seconds, the material has at least the surface energy of the value indicated on the ink. If the liquid contracts to drips, the surface tension is less than the reading indicated on the ink. To determine the exact surface tension, several inks with values above and below the first value were used. The test inks are after ISO 8296 produced.

It was found that a shaped body consisting of 96% by weight of PP or PE and 4% by weight of Dendrimer Boltorn H40 (Perstorp) has a surface tension which is at least 2 mN / m above the surface tension of the dendrimer-free PP or PE is.

To test the mechanical properties, the adhesive adhesion and the elongation at welds (welds) were determined on unreinforced or fiber-reinforced PP plates with and without incorporated dendrimer, cf. Table 1 (Adhesion) and Table 2 (Elongation).

It is shown in Table 1 that a fiber-reinforced PP molded body (PP LGF 20) with 5 wt .-% Dendrimer Boltorn H30 (Perstorp) has an adhesive force for an adhesive which is at least 25% above the adhesive force of the dendrimer free fiber reinforced PP lies.

With regard to the elongation properties in welding seams or welds on fiber-reinforced PP boards (PP LGF 20) with and without incorporated dendrimer shown in Table 2, that a welded, fiber-reinforced PP molding (PP LGF 20) with 3 wt .-% dendrimer Boltorn H40 (Perstorp) has improved elongation at break and tensile elongation at the welds that is at least 15% greater than the elongation at break and tensile elongation of the dendrimer-free fiber reinforced PP. Amount of adhesive substrate in g Adhesive force in N / 5cm PP LGF 20 59.2 70 PP LGF20 / 5% Boltorn H 30 59.6 91 PP LGF20 / 5% Boltorn H 40 62 61 PP T 20 56.6 12 Table 1. Borealis PPLGF20 + [% by weight] Breaking strain in% Tensile strain in% tensile strenght PP LGF20 6.8 6.78 18.2 3% Boltorn H40 7.8 7.8 15.7 Table 2

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2007/075927 [0008]
• WO 2008/003470 [0009]

Cited non-patent literature

• ISO 8296 [0034]

Claims (13)

 A molding composition containing at least one thermoplastic and a dendrimer, said dendrimer having a core, a plurality of branching generations, and a periphery of functional reactive hydroxyl groups.  The molding composition of claim 1, wherein the core and branches of the dendrimer are formed from silicon-free compounds.  Molding composition according to claim 1 or 2, wherein the core of the dendrimer is formed from a hyperbranched polyether polyol based on trimethylolpropane (TMP) and pentaerythritol (PEA) or derivatives thereof.  A molding composition according to claim 1, wherein the at least one plastic is contained at 80 to 99.999 wt .-% and the dendrimer to 0.001 to 20 wt .-%.  Molding composition according to one of claims 1 or 2, wherein the plastic is selected from the group consisting of acrylonitrile-butadiene-styrene (ABS), styrene-acrylonitrile (SAN), polystyrene (PS), polycarbonate (PC), polyethylene (PE), Polypropylene (PP), polyamides (PA), polyesters (PET), or mixtures thereof.  A molded article made from a molding composition according to any one of claims 1-5, wherein the molded article has a surface tension that is at least 1.5 mN / m above the surface tension of the dendrimer-free plastic.  Shaped body, produced from a molding composition according to any one of claims 1-5, wherein the shaped body has an adhesive force for an adhesive, in particular an adhesive having isocyanate groups, which is at least 25% above the adhesive force of the dendrimer-free plastic.  Shaped body produced from a molding composition according to any one of claims 1-5, wherein the welded shaped body has an elongation at break and / or tensile elongation at the welds, which is at least 15% above the breaking elongation and / or tensile elongation at the welds of the dendrimer-free plastic ,  Shaped body according to claim 6 or 7, wherein the functional, reactive hydroxyl groups of the dendrimer for chemical, especially covalent bonding with suitable adhesives, paints and / or foams are determined.  Shaped body according to claim 7 or 9, wherein adhesives, lacquers and / or foams have isocyanate groups, which are intended for chemical bonding with the functional, reactive hydroxyl groups of the dendrimer.  Shaped body according to one of claims 6-8, the dendrimers are arranged or enriched with their functional, reactive hydroxyl groups at least partially on the surface of the shaped body.  Process for producing a coated, lacquered, foam-backed or glued molded article according to one of claims 6 to 11, comprising a) mixing at least one thermoplastic with the dendrimer b) melting the molding composition under pressure; c) extruding the homogenized melt or injection molding into an injection mold; d) cooling, demolding and heating of the resulting molded body; e) welding the shaped body or applying an adhesive, lacquer or foam layer, wherein no additional activation of the shaped body surface takes place.  Use of a shaped article according to any one of claims 6 to 11 or a molding composition according to claim 1 to 5, as a component, wherein the component is a coated, painted, foam-backed, welded or glued car, aircraft or marine accessory or part of a car, aircraft - or marine accessory, preferably a coated, foam-backed, glued or laminated interior component is.

Images