EP1824941A1

EP1824941A1 - Two-component polyurethane adhesives, additives for two-component polyurethane adhesives and use of said additives

Info

Publication number: EP1824941A1
Application number: EP05812167A
Authority: EP
Inventors: Petra Padurschel; Rolf Tenhaef; Olaf Lammerschop; Thomas Huver; Hubert Schenkel; Andreas Ferencz
Original assignee: Henkel AG and Co KGaA
Current assignee: Henkel AG and Co KGaA
Priority date: 2004-11-30
Filing date: 2005-11-21
Publication date: 2007-08-29
Also published as: WO2006058624A1; DE102004057699A1; US20070282090A1; KR20070085585A; JP2008521979A

Abstract

The invention relates to a two-component polyurethane adhesive based on a polyol component and a polyisocyanate component. An adhesive bond, produced with said adhesive, of two sheets of steel coated with a cathodic electrodeposition paint has an impact peel strength of at least 11 N/mm according to ISO 11343 at a temperature of 40° C. The invention also relates to an additive for polyurethane adhesives and to the use of said additive.

Description

Two-component polyurethane adhesives,

Additives for two-component polyurethane adhesives and

Use of additives

The invention relates to a two-component polyurethane adhesive based on a polyol component and a polyisocyanate component. The invention also relates to an additive for such an adhesive and the use of the additive.

Polyurethane adhesives are described, for example, in the following patent applications or patents: EP 0 504 436 B1, EP 0 411 432 B1, EP 0 442 084 B1, DE 40 33 221 A1, EP 0 597 636 B1 and EP 0 740 675 B1.

Polyurethane adhesives have long been known and widely used. Particularly important, especially in technical applications, are the two-component adhesives, which are stirred by the user before use to a reaction mixture, which then hardens after application to the substrates to be bonded. Such two-component adhesives consist of a polyol component and an isocyanate component of functionality 2 or higher. These adhesives are preferred over other adhesives for many applications because the adhesive bonds made with them have outstanding tack, flexibility, and resistance to shock and fatigue.

In machine, vehicle or equipment construction, in particular in aircraft construction, rail vehicle construction or motor vehicle construction, the components made of the various metallic components and / or composite materials are increasingly joined with the aid of adhesives. For structural bonds with high strength requirements, epoxy adhesives have hitherto been used extensively, in particular as hot-curing one-component adhesives, which are frequently also formulated as reactive hot-melt adhesives. Reactive hot melt adhesives are solid at high temperatures. They soften at temperatures up to about 80 - 90 ⁰ C and behave like a thermoplastic material. Only at higher temperatures from about 100 ⁰ C present in these hot melt adhesives latent curing agent are thermally activated, so that irreversible curing takes place to a thermoset. For joining the components, for example, in the vehicle industry, the adhesive is first applied warm to at least one substrate surface, the components to be joined are then joined. Upon cooling, the adhesive solidifies and, by this physical solidification, provides sufficient handling strength, ie a preliminary bond. The so interconnected components are further treated in various washing, phosphating and dip coating. Only then is the adhesive cured in an oven at higher temperatures.

Deviating from this hitherto customary way of working, in particular in the vehicle industry, there is the desire to carry out the pretreatment of the components to be joined, including the electrodeposition coating, before the parts are bonded. So it should be glued metal parts, which have on its surface a cured electrocoating.

Although polyurethane adhesives provide excellent adhesive bonds in many applications, the heretofore known adhesives of this type are not suitable for the structural bonding of painted metal or composite workpieces because they do not have sufficient low temperature impact strength.

The present invention therefore has for its object to provide two-component polyurethane adhesives, which in the temperature range from - have a high strength 40 ⁰ C to +80 ⁰ C, without becoming brittle in the range of low temperatures. As a measure of the impact strength of the adhesive, the impact peel strength according to ISO 11343 apply.

Surprisingly, it has been found that the aforementioned object can be achieved in that two-component polyurethane adhesives special Additives are added, which increase the impact resistance of the adhesive bonds.

The present invention is therefore a two-component polyurethane adhesive based on a polyol component and a polyisocyanate component, which is characterized in that an adhesive bond produced by the adhesive of two coated with cathodic electrodeposition paint steel sheets at a temperature of -40 ⁰ C. has a peel strength to ISO 11343 of at least 11 N / mm. Two-component polyurethane adhesives with such impact peel strength are not yet known.

The selection of the polyol component and the polyisocyanate component are not critical to the present invention. Suitable polyol components are both low molecular weight polyols and relatively high molecular weight polyols, for example hydroxyl-bearing polyesters, which have at least 2 hydroxyl groups per molecule. As a polyisocyanate component, the usual Isocyanathärter are suitable for polyurethane adhesives having at least 2 isocyanate groups per molecule. Examples of suitable polyol components are liquid polyhydroxy compounds having two or three hydroxyl groups per molecule, such as. B. di- and / or trifunctional polypropylene glycols in the molecular weight range from 200 to 6000, preferably in the range of 400 to 3000. It can also be used random and / or block copolymers of ethylene oxide and propylene oxide. Another group of preferably used polyether polyols are the polytetramethylene glycols, z. Example, be prepared by the acidic polymerization of tetrahydrofuran, wherein the molecular weight range of the polytetramethylene glycols preferably between 200 and 6000, more preferably in the range of 400 to 4000. Furthermore, as the polyols, the liquid polyesters are suitable, which by condensation of di- or tricarboxylic acids, such as. B. adipic acid, sebacic acid, glutaric acid with low molecular weight diols or triols such. For example, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, 1, 4-butanediol, 1, 6-hexanediol, glycerol or trimethylolpropane can be produced. Another group The polyols which can be used are the polyesters based on lactones, such as caprolactone or valerolactone. However, it is also possible to use polyester polyols of oleochemical origin. Such polyester polyols can be prepared, for example, by complete ring opening of epoxidized triglycerides of a fat mixture containing at least partially olefinically unsaturated fatty acid with one or more alcohols having 1 to 12 carbon atoms and subsequent partial transesterification of the triglyceride derivatives to alkyl ester polyols having 1 to 12 carbon atoms in the alkyl radical. Other suitable polyols are polycarbonate polyols and dimer diols, and in particular castor oil and its derivatives. The hydroxy-functional polybutadienes, as z. B. under the trade name "poly-BD" are available, can be used for the inventive compositions as polyols.

Suitable polyisocyanates are, for example, aromatic isocyanates, eg. As diphenylmethane diisocyanate, either in the form of the pure isomers, as a mixture of isomers of 2,4 '- / 4,4'-isomers or the liquefied with carbodiimide diphenylmethane diisocyanate (MDI), the z. B. under the trade name Isonate 143 L is known. In addition, the so-called "crude MDI", that is to say the isomer / oligomer mixture of the MDI, can be used as described, for example, in US Pat. B. under the trade name PAPI or Desmodur VK are commercially available. Furthermore, so-called quasi-prepolymers, d. H. Reaction products of MDI or toluene diisocyanate (TDI) with low molecular weight diols such. For example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol or triethylene glycol can be used. Although the aforementioned isocyanates are the most preferred isocyanates, aliphatic or cycloaliphatic di- or polyisocyanates can be used such. Hydrogenated MDI (H12MDI), tetramethylxylylene diisocyanate (TMXDI), 1-isocyanatomethyl-3-isocyanato-1,5,5-trimethyl-cyclohexane (IPDI), hexane-1,6-diisocyanate (HDI), biuretization product of HDI, Isocyanuration product of HDI or dimer fatty acid diisocyanate.

Suitable polyols are compounds having at least two hydroxyl groups. Suitable polyols are preferably the liquid Polyhydroxy compounds having two or three hydroxyl groups per molecule, such as. B. di- and / or trifunctional polypropylene glycols in the molecular weight range from 200 to 6000, preferably in the range of 400 to 3000. It can also be used random and / or block copolymers of ethylene oxide and propylene oxide. Another group of preferably used polyether polyols are the polytetramethylene glycols, z. Example, be prepared by the acidic polymerization of tetrahydrofuran, wherein the molecular weight range of the polytetramethylene glycols preferably between 200 and 6000, more preferably in the range of 400 to 4000. Furthermore, as the polyols, the liquid polyesters are suitable, which by condensation of di- or tricarboxylic acids, such as. B. adipic acid, sebacic acid, glutaric acid with low molecular weight diols or triols such. For example, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, 1, 4-butanediol, 1, 6-hexanediol, glycerol or trimethylolpropane can be produced. Another group of usable polyols are the lactones-based polyesters, such as caprolactone or valerolactone. However, it is also possible to use polyester polyols of oleochemical origin. Such polyester polyols can be prepared, for example, by complete ring opening of epoxidized triglycerides of a fat mixture containing at least partially olefinically unsaturated fatty acid with one or more alcohols having 1 to 12 carbon atoms and subsequent partial transesterification of the triglyceride derivatives to alkyl ester polyols having 1 to 12 carbon atoms in the alkyl radical. Other suitable polyols are polycarbonate polyols and dimer diols, and in particular castor oil and its derivatives. The hydroxy-functional polybutadienes, as z. B. under the trade name "poly-BD" are available, can be used for the inventive compositions as polyols.

To measure the impact peel strength, two specimens are glued together. The adhesive seam, ie the joint, is dynamically loaded with a wedge, which occurs at a defined speed on it. It measures the load at which bonding is separated. The aforesaid value of impact peel strength according to ISO 11343 is measured in detail under the following conditions:

The test specimens consist of steel coated with cathodic electrodeposition paint (KTL) and have a size of 20 × 90 mm ² . The size of the adhesive surface was 20 × 30 mm ² , and the thickness of the adhesive layer was 0.2 mm. The wedge had a length of 14 mm and a height of 4 mm. The angle between the faces of the wedge was 8 ° 46 '18 ". It was moved at a speed of 2 ms ^{" 1} . These conditions apply to all impact peel strength values stated in this application.

Advantageously, an adhesive bond produced with the adhesive at a temperature of -40 ° C a impact peel strength according to ISO 11343 of at least 15 N / mm.

A two-component polyurethane adhesive, which leads to the said high impact peel strength, can be achieved in that, in addition to at least one polyol component and at least one polyisocyanate component as an additive, at least one hydroxyl- or amine-terminated reaction product of a hydroxyl-terminated compound Amino groups of the general formula (I)

HXf (CH ₂ ) _m -O-] _n XH,

wherein R = H or a straight-chain or branched alkyl radical having 1 to 20

Carbon atoms, m = 3 or 4 and n = 5 to 50, with a di- or tricarboxylic acid or a di- or triisocyanate. The additives are reactive prepolymers which when cured react with the resin component of the adhesive so that the additives are firmly incorporated into the polymer structure. As a result, soft phases are introduced into the adhesive bond, which cause the adhesive bond is retained even in a strong shock or impact. The soft phases absorb the energy of a shock, and the bond is impact resistant.

The compound of the formula (I) used for the preparation of the additive is advantageously polytetrahydrofuran or polytetramethylene oxide-di-p-aminobenzene.

The dicarboxylic acid to be used is advantageously a dimerized fatty acid, and a preferred diisocyanate is the diphenyl diisocyanate.

The adhesive according to the invention advantageously contains the additive in an amount of 5 to 30% by weight, based on the total weight of the adhesive, preferably 10 to 20% by weight, very particularly preferably 13 to 17% by weight.

The invention also relates to the additive for two-component polyurethane adhesives, which consists of a hydroxyl- or an amine-terminated reaction product of a compound having terminal hydroxyl or amino groups of the general formula (I)

HXf (CH ₂ ) _m -O-} _n XH,

wherein R = H or a straight-chain or branched alkyl radical having 1 to 20

Is carbon atoms, m is 3 or 4 and n is 5 to 50, with a di- or tricarboxylic acid or a di- or triisocyanate.

Advantageously, the additive has a number average molecular weight of from 1000 to 20 000 g / mol, preferably from 1000 to 12000 g / mol, very particularly preferably from 2000 to 8000 g / mol.

The invention further relates to the use of a hydroxyl- or amine-terminated reaction product of a compound having terminal hydroxyl or amino groups of the general formula (I)

where R = H or a straight-chain or branched alkyl radical having 1 to 20 carbon atoms, m = 3 or 4 and n = 5 to 50, with a di- or tricarboxylic acid or a di- or triisocyanate as an additive in two-component Polyurethane adhesives for improving the impact peel strength of adhesive bonds made with the adhesives.

In the following the invention will be explained in more detail with reference to embodiments. embodiments

The experiments described below were carried out with the commercially available polyurethane adhesive Terokal 806 N from Henkel Teroson GmbH.

Basic formulation of the adhesive Terokal 806 N (basic recipe):

Component A (resin):

95% Baycoll VP 8576 (Bayer AG, resin component polyol base)

5% Baylith powder (Bayer AG, drying agent)

Component B (hardener):

100% Makroplast UK 5400 (Henkel KGaA, hardener, diphenyl-4,4'-diisocyanate)

Mixing ratio:% by weight 1, 3 (A): 1 (B)

To increase the impact strength, the additives were incorporated in the basic formulation and bonded to cathodically dip-coated test specimens. The adhesive bonds were subjected to various destructive test methods, such as pull shear, peel and impact peel tests.

example 1

Additive Synthesis:

Polytetramethylene oxide di-p-aminobenzene and diphenyl-4,4'-diisocyanate are converted by a polyaddition to a prepolymer.

This is 0.09 mol (111, 4 g) of polytetramethylene oxide di-p-aminobenzene in one

Round bottom flask with gas inlet, condenser and stirrer and submitted with stirring. 1

Hour dried at 100 ⁰ C under high vacuum. Then it is aerated with nitrogen and cooled to 40 ⁰ C. Thereafter, 0.06 mol (15.0 g) rapidly

Diphenyl-4,4'-diisocyanate added. The rapidly homogenized solution shows a slightly exothermic reaction after about 15 minutes, the temperature rises to 47 ⁰ C. The viscosity increases strongly, so that the

Solidified reaction mixture to a non-stirrable, slightly elastic mass.

The reaction mixture is reacted for 1 hour at 100 ⁰ C and is then cooled to room temperature.

The no longer meltable substance is cooled with liquid nitrogen and ground. The product is in the form of a light yellow, fine and acetone-soluble powder and has an amine value of 41.2 (additive 1).

Adhesive formulation:

8 g of resin (see basic recipe)

2 g of additive 1

6.3 g hardener (see basic recipe)

This mixture is stirred intimately and quickly and glued on KTL specimens.

Results:

Room temperature 0 ° C -20 ° C -40 ° C

Impact peel strength 26.3 N / mm 25, 8 N / mm 22.8 N / mm 14.2 N / mm

room temperature

Peel strength 6.7 N / mm Example 2

Additive Synthesis:

This is 0.2 mol (171, 96 g) of polytetramethylene oxide di-p-aminobenzene in one

Hour dried at 100 ⁰ C under high vacuum. Then it is aerated with nitrogen and cooled to 40 ⁰ C. Then 0.15 mol (37.5 g) are added quickly

Solidified reaction mixture to a non-stirrable, slightly elastic mass.

The reaction mixture is reacted for 1 hour at 100 ⁰ C and then on

Room temperature cooled.

The no longer meltable substance is cooled with liquid nitrogen and ground. The product is a light yellow, fine and acetone-soluble powder and has an amine value of 26.8 (additive 2).

Klebstofffomulierung:

8 g of resin (see basic recipe)

2 g of additive 2

6.3 g hardener (see basic recipe)

This mixture is stirred intimately and quickly and glued to KTL test specimens.

Results:

Room temperature 0 ° C -20 ° C -40 ° C

Impact peel strength 21, 8 N / mm 23, 0 N / mm 23.3 N / mm 11, 8 N / mm

Example 3

Additive Synthesis:

Dimer fatty acid (SZ 190) and polytetrahydrofuran 650 are replaced by a

Polycondensation converted to a prepolymer.

In a round bottom flask with gas transfer, thermometer and condenser with

Water separators are 0.05 mol (29.5 g) of dimer fatty acid, 0.1 mol (63 g)

Polytetrahydrofuran, 0.3 g of catalyst Swedcat 3 and 50 ml of solvent XyIoI under nitrogen transfer to 140 ⁰ C heated. By distilling off the XyIoIs the internal temperature rises to 195 ⁰ C, wherein the oil bath temperature is 220 ⁰ C.

The reaction continues until no more water of reaction forms in the water separator. After about 8 hours, cooled to 180 ⁰ C, the water removed and replaced by a descending cooler. In vacuo, the residual xylene and other volatiles are removed from the reaction mixture within 30 minutes. Finally, the reaction mixture was on

100 ⁰ C cooled and bottled the liquid product.

The product is deep yellow and honey-like at room temperature and has a

OH number of 56 (additive 3).

Adhesive formulation:

8 g of resin (see basic recipe)

2 g of additive 3

6.47 g hardener (see basic recipe)

This mixture is stirred intimately and quickly and glued on KTL specimens.

Results:

Example 4

Additive Synthesis:

Polytetrahydrofuran 650 and diphenyl-4,4'-diisocyanate are replaced by a

Polyaddition converted to a prepolymer.

To this is added 0.15 mol (94.5 g) of polytetrahydrofuran in a round bottom flask

Gas inlet, thermometer, condenser and stirrer and submitted with stirring. 1

Hour dried at 100 ⁰ C under high vacuum. Then it is aerated with nitrogen and cooled to 40 ⁰ C. Thereafter, 0.10 mol (25.0 g) quickly

Diphenyl-4,4-diisocyanate added. The rapidly homogenized solution shows a slightly exothermic reaction after about 15 minutes, the temperature rises to 67 ⁰ C. At the same time, the viscosity of the reaction mixture increases, whereby it remains stirrable. For a complete post-reaction that will

Reaction mixture stirred at 80 ⁰ C for a further 3 hours. Finally, on 40

^{Cooled 0} C and bottled the product. It is at room temperature as a colorless, non-flowable resin and has an OH number of 48 (additive 4).

Adhesive formulation:

8 g of resin (see basic recipe)

2 g of additive 4

6.42 g hardener (see basic recipe)

This mixture is stirred intimately and quickly and glued on KTL specimens.

Results:

Example 5 Additive Synthesis:

Polytetrahydrofuran 2000 and diphenyl-4,4'-diisocyanate are converted by a polyaddition to a prepolymer.

For this purpose, 0.05 mol (101, 3 g) of polytetrahydrofuran in a round bottom flask with gas inlet, thermometer, condenser and stirrer and dried under stirring for 1 hour at 100 ⁰ C in a high vacuum. Then it is aerated with nitrogen and cooled to 40 ⁰ C. Thereafter, 0.025 mol (6.25 g) of diphenyl-4,4'-diisocyanate are added quickly. The rapidly becoming homogeneous solution shows after 15 minutes a slightly exothermic reaction, the temperature rises up to 67 ⁰ C. At the same time, the viscosity of the reaction mixture increases, whereby it remains stirrable. For a complete post-reaction, the reaction mixture is stirred for a further 3 hours at 80.degree. Finally, it is cooled to 40 ^° C. and the product is bottled. It is present at room temperature as a white, slightly waxy or rubbery resin and has an OH number of 44 (additive 5).

Adhesive formulation:

8 g of resin (see basic recipe)

2 g of additive 5

6.31 g hardener (see basic recipe)

This mixture is stirred intimately and quickly and glued to KTL test specimens.

Results:

Example 6

Additive Synthesis:

Polytetrahydrofuran 650 and diphenyl-4,4'-diisocyanate are replaced by a

Polyaddition converted to a prepolymer.

For this purpose, 0.01 mol (64.9 g) of polytetrahydrofuran in a round bottom flask

Gas inlet, thermometer, condenser and stirrer and submitted with stirring. 1

Hour dried at 100 ⁰ C under high vacuum. Then it is aerated with nitrogen and cooled to 40 ⁰ C. Thereafter, 0.08 mol (20 g) of diphenyl

4,4'-diisocyanate added. The rapidly becoming homogeneous solution shows after about 15 minutes an exothermic reaction, the temperature rises up to 90 ⁰ C. At the same time, the viscosity of the reaction mixture increases. For a complete post-reaction, the reaction mixture is at 80 for a further 3 hours

⁰ C annealed without stirring. Finally, it is cooled to 40 ⁰ C and the

Product bottled. It is at room temperature as white, rubbery, geliges

Resin before and is meltable. It has an OH number of 26 (Additive 6).

Adhesive formulation:

8 g of resin (see basic recipe)

2 g of additive 6

6.30 g hardener (see basic recipe)

This mixture is stirred intimately and quickly and glued on KTL specimens.

Results:

Example 7 Additive Synthesis

Polytetrahydrofuran 650 and diphenyl-4,4'-diisocyanate are converted by a polyaddition to a prepolymer.

For this purpose, 0.14 mol (90.9 g) of polytetrahydrofuran in a round bottom flask with gas inlet, thermometer, condenser and stirrer and dried under stirring for 1 hour at 100 ⁰ C under high vacuum. Then it is aerated with nitrogen and cooled to 40 ⁰ C. Thereafter, 0.12 mol (30 g) of diphenyl-4,4'-diisocyanate are added rapidly. The rapidly becoming homogeneous solution shows after about 15 minutes an exothermic reaction, the temperature rises up to 90 ⁰ C. At the same time, the viscosity of the reaction mixture increases. For a full-reaction, the reaction mixture for an additional 3 hours at 80 ⁰ C is annealed without stirring. Finally, it is cooled to 40 ° C and bottled the product. It is at room temperature as a tacky, rubbery and geliger resin before and is no longer flowable in the heat. It has an OH number of 18.5 (Additive 7).

Adhesive formulation:

8 g of resin (see basic recipe)

2 g of additive 7

6.26 g hardener (see basic recipe)

This mixture is stirred intimately and quickly and glued on KTL specimens.

Results:

Example 8 Additive Synthesis

For this purpose, 0.09 mol (58.4 g) of polytetrahydrofuran is placed in a round bottom flask with gas inlet, thermometer, condenser and stirrer and dried under stirring for 1 hour at 100 ⁰ C under high vacuum. Then it is aerated with nitrogen and cooled to 40 ⁰ C. Thereafter, 0.08 mol (20 g) of diphenyl-4,4'-diisocyanate are added quickly. The rapidly becoming homogeneous solution shows after about 15 minutes an exothermic reaction, the temperature rises up to 95 ⁰ C. At the same time, the viscosity of the reaction mixture increases. For a full-reaction, the reaction mixture for an additional 3 hours at 80 ⁰ C is annealed without stirring. Finally, it is cooled to 40 ^° C. and the product is bottled. It is at room temperature as a tacky, rubbery, geliges resin before and is no longer flowable in the heat. It has an OH number of 14.3 (additive 8).

Adhesive formulation:

8 g of resin (see basic recipe)

2 g of additive 8

6.23 g hardener (see basic recipe)

This mixture is stirred intimately and quickly and glued to KTL test specimens.

Results:

Example 9

additive synthesis

Polytetrahydrofuran 1000 and diphenyl-4,4'-diisocyanate are by a

Polyaddition converted to a prepolymer.

To this is added 0.09 mol (97.1 g) of polytetrahydrofuran in a round bottom flask

Gas inlet, thermometer, condenser and stirrer and submitted with stirring. 1

Hour dried at 100 ⁰ C under high vacuum. Then it is aerated with nitrogen and cooled to 40 ⁰ C. Thereafter, 0.06 mol (15 g) of diphenyl

4,4'-diisocyanate added. The rapidly homogenous solution shows a slightly exothermic reaction after approx. 15 minutes and the temperature rises upwards

40 ⁰ C on. At the same time, the viscosity of the reaction mixture increases, whereby it remains barely stirrable. For a complete post-reaction that will

Reaction mixture stirred at 80 ⁰ C for a further 3 hours. Finally, on 40

^{Cooled 0} C and bottled the product. It is at room temperature as a white, highly viscous, rubbery resin. It has an OH number of 30 (Additive 9).

Adhesive formulation:

8 g of resin (see basic recipe)

2 g of additive 9

6.32 g hardener (see basic recipe)

This mixture is stirred intimately and quickly and glued to KTL test specimens.

Results:

Example 10 Additive Synthesis

Polytetrahydrofuran 1000 and diphenyl-4,4'-diisocyanate are converted by a polyaddition to a prepolymer.

For this purpose, 0.1 mol (107.9 g) of polytetrahydrofuran is placed in a round bottom flask with gas inlet, thermometer, condenser and stirrer and dried under stirring for 1 hour at 100 ⁰ C under high vacuum. Then it is aerated with nitrogen and cooled to 40 ⁰ C. Thereafter, 0.08 mol (20 g) of diphenyl-4,4'-diisocyanate are added quickly. The rapidly homogenizing solution shows a slightly exothermic reaction after about 15 minutes, the temperature rises to 40 ^° C. At the same time, the viscosity of the reaction mixture increases, whereby it remains barely stirrable. For a full-reaction, the reaction mixture is stirred for a further 3 hours at 80 ⁰ C. Finally, it is cooled to 40 ^° C. and the product is bottled. It is at room temperature as a white, rubbery resin and is still fluid in the heat. It has an OH number of 17.5 (additive 10).

Adhesive formulation:

8 g of resin (see basic recipe)

2 g of additive 10

6.25 g hardener (see basic recipe)

This mixture is stirred intimately and quickly and glued on KTL specimens.

Results:

Example 11 Additive Synthesis

For this purpose, 0.07 mol (75.5 g) of polytetrahydrofuran in a round bottom flask with gas inlet, thermometer, condenser and stirrer and dried under stirring for 1 hour at 100 ⁰ C in a high vacuum. Then it is aerated with nitrogen and cooled to 40 ⁰ C. Thereafter, 0.06 mol (15 g) of diphenyl-4,4'-diisocyanate are added quickly. The rapidly homogenizing solution shows a slightly exothermic reaction after about 15 minutes, the temperature rises up to 40 ^C C. At the same time, the viscosity of the reaction mixture increases, whereby it remains barely stirrable. For a full-reaction, the reaction mixture is stirred for a further 3 hours at 80 ⁰ C. Finally, it is cooled to 40 ^° C. and the product is bottled. It is present as a white, gelatinous resin at room temperature and is heat-curable. It has an OH number of 12.4 (additive 11).

Adhesive formulation:

8 g of resin (see basic recipe)

2 g of additive 11

6.23 g hardener (see basic recipe)

This mixture is stirred intimately and quickly and glued to KTL test specimens.

Results:

Example 12 Additive Synthesis

For this purpose, 0.045 mol (91, 2 g) of polytetrahydrofuran in a round bottom flask with gas inlet, thermometer, condenser and stirrer and dried with stirring for 1 hour at 100 ⁰ C under high vacuum. Then it is aerated with nitrogen and cooled to 40 ⁰ C. Thereafter, 0.03 mol (7.5 g) of diphenyl-4,4'-diisocyanate are added quickly. The rapidly homogenizing solution shows a slightly exothermic reaction after about 15 minutes, the temperature rises to 35 ⁰ C. At the same time the viscosity of the reaction mixture increases, whereby it gelifies gel. For a full-reaction, the reaction mixture is stirred for a further 3 hours at 80 ⁰ C. Finally, it is cooled to 40 ^° C. and the product is bottled. It is at room temperature as a white, gelatinous resin and is just flowable in the heat. It has an OH number of 17.1 (additive 12).

Adhesive formulation:

8 g of resin (see basic recipe)

2 g of additive 12

6.25 g hardener (see basic recipe)

This mixture is stirred intimately and quickly and glued on KTL specimens.

Results:

Example 13 Additive Synthesis

For this purpose, 0.04 mol (81, 0 g) of polytetrahydrofuran in a round bottom flask with gas inlet, thermometer, condenser and stirrer and dried under stirring for 1 hour at 100 ⁰ C under high vacuum. Then it is aerated with nitrogen and cooled to 40 ⁰ C. Thereafter, 0.03 mol (7.5 g) of diphenyl-4,4'-diisocyanate are added quickly. The rapidly homogenizing solution shows a slightly exothermic reaction after about 15 minutes, the temperature rises to 35 ⁰ C. At the same time, the viscosity of the reaction mixture increases, whereby it hardly remains stirrable. For a full-reaction, the reaction mixture is stirred for a further 3 hours at 80 ⁰ C. Finally, it is cooled to 40 ^° C. and the product is bottled. It is present at room temperature as a white, rigid, hardly flowable resin and can be melted again. It has an OH number of 12.7 (additive 13).

Adhesive formulation:

8 g of resin (see basic recipe)

2 g of additive 13

6.23 g hardener (see basic recipe)

This mixture is stirred intimately and quickly and glued on KTL specimens.

Results:

Example 14 Additive Synthesis

For this purpose, 0.12 mol (78.0 g) of polytetrahydrofuran in a round bottom flask with gas inlet, thermometer, condenser and stirrer and dried under stirring for 1 hour at 100 ⁰ C under high vacuum. Then it is aerated with nitrogen and cooled to 40 ⁰ C. Thereafter, 0.11 mol (27.5 g) of diphenyl-4,4'-diisocyanate are added quickly. The rapidly becoming homogeneous solution shows after 15 minutes a slightly exothermic reaction, the temperature rises up to 57 ⁰ C. At the same time, the viscosity of the reaction mixture increases. The mixture is no longer stirrable after 20 minutes. For a full-reaction, the reaction mixture for an additional 3 hours at 80 ⁰ C is annealed without stirring. Finally, it is cooled to 40 ^° C. and the product is bottled. It is at room temperature as a white, solid, rubbery resin and has an OH number of 10.7 (Additive 14).

Adhesive formulation:

8 g of resin (see basic recipe)

2 g of additive 14

6.21 g hardener (see basic recipe)

This mixture is stirred intimately and quickly and glued on KTL specimens.

Results:

Example 15 Additive Synthesis

For this purpose, 0.05 mol (101, 3 g) of polytetrahydrofuran in a round bottom flask with gas inlet, thermometer, condenser and stirrer and dried under stirring for 1 hour at 100 ⁰ C in a high vacuum. Then it is aerated with nitrogen and cooled to 40 ⁰ C. Thereafter, 0.04 mol (10.0 g) of diphenyl-4,4'-diisocyanate are added quickly. The rapidly homogenizing solution shows a slightly exothermic reaction after approx. 15 minutes and the temperature rises to 55 ° C. At the same time, the viscosity of the reaction mixture increases. For a full-reaction, the reaction mixture for an additional 3 hours at 80 ⁰ C is annealed without stirring. Finally, it is cooled to 40 ^° C. and the product is bottled. It is at room temperature as a slightly cloudy, rubbery, non-flowable resin and has an OH number of 10.3 (Additive 15).

Adhesive formulation:

8 g of resin (see basic recipe)

2 g of additive 15

6.21 g hardener (see basic recipe)

This mixture is stirred intimately and quickly and glued on KTL specimens.

Results:

5

Comparative tests

For comparison, cathodically exchange-coated test specimens were glued in the same way as in the embodiments with the adhesive Terokal 806 N according to the base formulation without the addition of an additive. The measurement of impact peel strength gave a value of 10.6 N / mm.

Claims

claims

1. A two-component polyurethane adhesive based on a polyol component and a polyisocyanate component, characterized in that an adhesive bond produced by the adhesive of 2 coated with cathodic electrodeposition paint steel sheets at a temperature of -40 ° C a impact peel strength according to ISO 11343 of at least 11 N / mm ,

2. An adhesive according to claim 1, characterized in that an adhesive bond produced by the adhesive of 2 coated with cathodic electrodeposition paint steel sheets at a temperature of -40 ⁰ C has a impact peel strength according to ISO 11343 of at least 15 N / mm.

3. An adhesive according to claim 1 or 2, characterized in that it contains at least one reaction product in addition to at least one polyol component and at least one polyisocyanate as an additive containing one or more terminal hydroxyl, amino or isocyanate groups and can be prepared by reacting with a compound terminal hydroxyl or amino groups of the general formula (I)

in the X = -O- or

where R is H or a straight-chain or branched alkyl radical having 1 to 20 carbon atoms, m is 3 or 4 and n is 5 to 50, with a di- or tricarboxylic acid or a di- or triisocyanate.

4. An adhesive according to claim 3, characterized in that the compound of formula (I) is polytetrahydrofuran or polytetramethylene oxide di-p-aminobenzene.

5. An adhesive according to claim 3 or 4, characterized in that the dicarboxylic acid is a dimerized fatty acid.

6. An adhesive according to claim 3 or 4, characterized in that the diisocyanate is diphenyl diisocyanate.

7. An adhesive according to claim 3 to 6, characterized in that the additive is contained in an amount of 5 to 30 wt .-% based on the total weight of the adhesive in this.

8. An additive for two-component polyurethane adhesives consisting of a reaction product which contains one or more terminal hydroxyl, amino or isocyanate groups and can be prepared by reacting a compound having terminal hydroxyl or amino groups of the general formula (I)

HXf (CH ₂ ) _m -O-} _n XH,

in the X = -O- or

wherein R = H or a straight-chain or branched alkyl radical having 1 to 20

Carbon atoms, m = 3 or 4 and n = 5 to 50, with a di- or tricarboxylic acid or a di- or triisocyanate.

9. An additive according to claim 8, characterized in that its number-average molecular weight is 1000 to 20,000 g / mol.

10. Use of a reaction product which contains one or more terminal hydroxyl, amino or isocyanate groups and can be prepared by reacting a compound having terminal hydroxyl or amino groups of the general formula (I)

HXt (CH ₂ ) _m -O-} _n XH,

in the X = -O- or

wherein R = H or a straight-chain or branched alkyl radical having 1 to 20

Carbon atoms, m = 3 or 4 and n = 5 to 50, with a di- or tricarboxylic acid or a di- or triisocyanate as an additive in two-component polyurethane adhesives to improve

Impact peel strength of adhesives produced with the adhesives

Adhesive bonds.