CZ200086A3 - Thixotropic two-component polyurethane systems, process of their preparation and their use - Google Patents

Abstract

The solution concerns two-component polyurethane systems, which comprise a polyol and an isocyanate component. Polyol the component contains at least two amines A1 and A2, wherein the reactivity of R1 amine 1 to the isocyanate component is substantially greater than the reactivity of R 2 amine 2 to the isocyanate component. As a result, two are running in time with respect to each other shifted responses that make the system initially low the viscosity required for application and after application it gets thixotropic properties that are on the vertical even thick layers can be avoided. Solve it further relates to a process for producing a two-component polyurethane a system in which the amine component is dissolved in the polyol a second amine component is added using a stirrer the desired ingredients and the resulting mixture in the blending a with the diisocyanate. Two-component the polyurethane system can be used to form shaped bodies for Cubing models, early models and the like in the automotive industry and for the manufacture of structured bodies, thick layers and sealing beads.

Description

Thixotropic two-component polyurethane systems, process of their production and their use

Technical field

The invention relates to thixotropic two-component polyurethane systems which consist of a polyol and an isocyanate component. The invention further relates to a process for the production and use of these thixotropic two-component polyurethane systems.

BACKGROUND OF THE INVENTION

In many applications of 2K polyurethane systems (2K PUR), in particular for the production of moldings for Cubing models, early models and the like in the automotive industry, these two-component systems are required to be thixotropic immediately after machine mixing and application, Application on vertical surfaces, even in thick layers, tendency to run down or slip.

Hitherto, paste polyurethane systems with fillers have been used for this purpose, most often in the polyol component containing inorganic and / or organic thickening materials. DE-PS 27 51 761 also discloses a composition as a thixotropic coating material consisting of a binder and a reaction product of a diisocyanate with a primary or secondary polyamine, in particular benzylamine, which controls the flowability.

Also described as thixotropic agents in EP-A 0 006 252, p. 1 are polyamide resins with free amino groups which can be incorporated into the resin lacquers to form a gel.

··· · · ···

It is also known that urea addition compounds resulting from the reaction of primary and / or secondary polyamines, monofunctional alcohols and / or amines with diisocyanate compounds prepared in situ with a binder or binder component have thixotropic effects as described in DE -PS 23 60 019.

DE-A 40 23 005 discloses thixotropic polyurethane systems based on a polyol and isocyanate component, the polyol component of which comprises a mixture of polyamidamine and low molecular weight multifunctional, in particular aromatic amines. The polyol, isocyanate and amine component mixture has a low viscosity for a short period of time, which is required for deposition, and then exhibits the thixotropic properties required to remain on the overhead or vertical surfaces. According to examples, polyurethane systems with a layer thickness of 5 mm are applied and used as adhesive systems, for example for glazing. In the polyurethane systems described in this document, a combination of two amines is used, but the isocyanate reacts approximately simultaneously to achieve the desired low viscosity and thixotropy properties. These systems are not suitable for applying layers of greater thickness, i.e. approximately 20 to 50 mm, since slipping of such layers due to the considerable reaction heat generated during the exothermic curing reaction cannot be completely excluded.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved two-component polyurethane system whose components shortly after mechanical mixing due to the chemical reaction obtain sufficient thixotropy to ensure, on the one hand, that sufficient fluidity is maintained in the applied strokes.

and, on the other hand, allowing the thick-layered strokes to be applied to vertical surfaces without slipping after such an exothermic curing reaction has started.

SUMMARY OF THE INVENTION

This problem is solved and the drawbacks of known solutions of this kind are largely eliminated by the two-component polyurethane system consisting of the polyol and isocyanate component according to the invention, characterized in that the polyol component contains at least two amines A1 and A2, the reactivity R1 of amine 1. to the isocyanate component is substantially greater than the reactivity of R2 of amine 2 to the isocyanate component.

The ratio of the reactivity R1 of amine 1 to the reactivity R2 of amine 2 to the isocyanate component is preferably 1000 to 5.

It is particularly preferred that the ratio of the reactivity R1 of amine 1 to the reactivity R2 of amine 2 relative to the isocyanate component is 100 to

5.

Preferably, amine 1 is selected from aromatic amines (group 1a), cycloaliphatic amines (group 1b), araliphatic amines (group 1c), and aliphatic amines and polyamines (group 1d).

Preferably, the amine 2 is selected from the group consisting of: methylene-bis- (3-chloro-2,6-diethylaniline) (M-CDEA),

3,5-dimethylthio-2,4- or -2,6-toluylenediamine,

3,5-diamino-4-chloro-isobutyl benzoate (DACB), methylene-bis-methyl anthranilic ester (MBMA),

4,4'-diamino-3,3'-dichlorodiphenylmethane (MOCA) • ·

- 4 and the like.

One preferred variant is that amine 1 is selected from groups 1 a) to 1 d) and amine 2 is selected from group 2.

Another preferred variant of the two-component polyurethane system of the invention is that amine 1 is selected from groups 1 a) to 1 d) and amine 2 is selected from group 1 a), wherein the reactivity R 1 of amine 1 from groups 1 b) to 1 d) is greater than the reactivity R 2 of the amine 2 of Group 1 a).

Preferably, amine 1 is 4,4'-diamino-3,3'-dimethylcyclohexylmethane and amine 2 is 4,4'-methylene-bis- (3-chloro-2,6-diethylaniline).

The weight ratio of amine 1 to amine 2 is preferably in the range of 0.5: 1 to 2: 1 in wt.

The proportion of amine 1 in the polyol component is preferably 0.25 to 5% by weight. and the proportion of amine 2 in the polyol component is 0.3 to 5 wt.

The polyol preferably consists of polyether polyols and / or polyester polyols in the molecular weight range of 75 to 6000 and the isocyanate is a 4,4'-diphenylmethane diisocyanate derivative.

The present invention also provides a process for the preparation of the disclosed two-component polyurethane system, which comprises dissolving the amine component in a polyol component, adding a second amine component and the desired ingredients with a mixer, and mixing the resulting mixture with a diisocyanate in a mixing and dispensing device.

• ·

The subject of the invention is also the use of the two-component polyurethane system described above for the production of moldings for Cubing models, early models and the like in the automotive industry and for the production of structured bodies, thick layers and sealing beads.

The two-component polyurethane system (2K PUR) described herein has the following advantageous properties:

1. Liquid consistency of the two starting components, thereby allowing easy miscibility of the two starting components;

2. Good castability of the individual coatings to achieve a minimum of air inclusions and a smooth surface;

3. Good stability of the deposited layer, due to which the deposited layers tend to slip on vertical surfaces;

4. Long post-processability, allowing a smooth coating and the like;

5. Possibility of applying multiple layers on top of each other with good cohesion between these layers;

6. Consistency at the time of application, which depends on the application rate and application path.

The polyurethane system according to the invention is based on a two-component polyurethane system (2K-PUR) which consists of two liquid components. The resin component consists of modified polyether polyols and / or polyester polyols with fillers, while the curing component consists of a low viscous isocyanate based on 4,4'-diphenylmethane diisocyanate (MDI).

According to the invention, it is essential that the thixotropic properties of the system occur over time such that, after mixing in the first phase, the reaction of the amine Al with the isocyanate is so thixotropic that it still wets the substrate well and flows well into depressions. it is already so stable that it adheres well to vertical surfaces even in a layer of 20 mm or more and does not slip off these vertical surfaces. However, since the structural viscosity achieved in the first stage is generally not sufficient to prevent slipping of the deposited layer after initiation of the crosslinking reaction and the attenuation of the intermolecular forces due to the released heat of reaction, a further delayed initiation reaction is required. Thus, in the second phase, a higher structural viscosity or thixotropy is achieved in the system by reacting the amine A2 with an isocyanate, which structural viscosity remains thermally stable and does not allow further run-off which occurs after the reaction in the first phase.

The modified two-component polyurethane system according to the invention thus performs two processing tasks, the first task being good wetting and casting or smoothing immediately after application on the substrate with good stability at temperatures up to about 40 ° C and the second task is good intermolecular cohesion after initiation a polyol / isocyanate curing reaction which is associated with an increase in temperature to about 80 ° C, thereby preventing even thick layers from slipping on vertical surfaces.

Both tasks cannot be solved by using only one amine or approximately simultaneously reacting amine mixtures. By increasing the amount of amine, possibly corresponding to the choice of amine, the second task of preventing the coating from slipping can be accomplished, but not simultaneously the first task of

- 7 good wetting and casting on the mat. However, it has been found that both tasks can be accomplished if at least two or more amines with significantly different reactivities are used. The reactivity R1 of amine 1 to the isocyanate component must be higher than the reactivity R2 of amine 2 to the isocyanate component. It has been found that the ratio of the reactivity R1 of amine 1 to the reactivity R2 of amine 2 to the isocyanate component should be about 1000 to 5 and preferably 100 to 5.

At time 0, the two components of the two-component polyurethane system are mechanically blended together. In the first phase, the reaction of amine 1 with the isocyanate begins within a few seconds. During this time, the deposited layer is essentially cast. In the second phase, following the reaction in the first phase, amine 2 reacts with the isocyanate within about 1 to 2 minutes and forms a cohesive gel structure due to the formation of hydrogen bonds and other intermolecular forces, so that during the peak time the polyol reacts with isocyanate, no more slippage of the deposited layer. The peak time is about 30 to 40 minutes, and without the amine 2 reaction, after about 20 minutes, the layer deposited on the vertical surface would slip.

Particularly suitable amines 1 which are added to the polyol component for the first-stage reaction and whose reactivity R1 > R2 include:

(a) aromatic amines such as

2,4- or 2,6-toluylenediamine (TDA)

3,5-diethyl-toluylenediamine (DETDA), methylene-bis- (2,6-diisopropylaniline) (M-DIPA), methylene-bis- (2-methyl-6-isopropylaniline) (M-MIPA), methylene-bis- ( 2,6-diethylaniline (M-DEA),

4,4'-methylene-bis- (6-methyl-aniline),

2, β-diisopropylaniline (DIPA),

2-Methyl-6-isopropylaniline (ΜΙΡΑ)

4,4'-diamino-diphenyl-methane (MDA),

(b) cycloaliphatic amines such as

3-Isocyanatomethyl-3,5,5-trimethylcyclohexylamine (isophorondiamine, IPD)

4,4'-diamino-3,3'-dimethyl-cyclohexylmethane, Laromin C 260, cyclohexanediamine, piperazine, N-aminoethylpiperazine,

(c) araliphatic amines such as m-xylylenediamine (M-XDA) and derivatives or other types having one aromatic and one aliphatic amine-linked group;

d) aliphatic amines and polyamines such as butylamine, diethylenetriamine, triethylenetetramine, trimethylhexamethylenediamine, pentaethylenehexamine, polyether polyamines such as H ₂ N- (CH ₂ -CH ₂ -O) _X -CH ₂ -CH ₂ -NH ₂ and derivatives.

Particularly suitable amines 2 which are added to the polyol component for the second phase of the reaction include, for example, the following amines in which R2 < R1 is:

methylene-bis- (3-chloro-2, β-diethylaniline) (M-CDEA),

3,5-dimethylthio-2,4- or -2,6-toluylenediamine marketed under the name Ethacure 300 by Ethyl Corp.,

Benzoic acid 3,5-diamino-4-chloro-isobutyl ester (DACB), anthranilic acid methylene-bis-methyl ester (MBMA),

4,4'-diamino-3,3'-dichlorodiphenylmethane (MOCA), or the like.

Type A2 amines are electronically valence or mesomeric phenomena due to reduced alkalinity and / or steric blocking of amines with strongly retarded reaction. It is critical that amine 2 has a appreciably less reactivity to the isocyanate than amine 1. It is also possible to combine amine 1 of groups 1 b) to 1 d) with amine 2 of group 1 a) if there are sufficient differences in reactivity in this combination. Mixtures of amines from individual groups can also be used.

A comparison of the relative reactivities of the amines from groups 1 a), 1 b) to d) and 2 is shown in Table 1 below:

Table 1 Amines from the group of relative reactivity

and)

(b), (c), (d)

0.1 to 15 5 to 200 100 to> 1000

In practice, this means that under the conditions of Examples 1 and 2, the amines of groups 1 b) to 1 d) react immediately with the isocyanate, the amines of group 1 a) in about 5 to 10 seconds and the amines of group 2 in about 30 seconds. up to 90 sec.

The above amine compounds may be mixed with suitable polyols in the form of liquid preparations. Suitable polyols •

Polyols known from polyurethane chemistry which contain at least two alcohol-bonded hydroxyl groups are suitable. These include known linear or branched polyether polyols having a molecular weight in the range of 75 to 6000, or known linear or branched polyester polyols having a molecular weight in the range of 75 to 6000, as described, for example, in DE-PS 21 60 589 or DE-A 33 40 588. The polyol components at 25 ° C have viscosities in the range of about 1,000 to 60,000 mPa · s. Other substances may also be included in the polyol components, for example desiccants, pigments, dispersants, plasticizers, antifoams, and optionally catalysts. These include, for example, the commercially available zeolite-type sodium potassium potassium aluminosilicate as desiccant, chalk, calcium carbonate, pigments, hydrocarbon-based plasticizers and optionally tertiary amines or organic tin compounds as catalysts.

Suitable isocyanate components are those which are also suitable for use in two-component polyurethane systems and are described, for example, in DE-PS 21 60 589 or DE-A 33 40 588. Aromatic diisocyanates, e.g. diphenylmethane diisocyanate (MDI) and toluylene diisocyanate (TDI). The isocyanate component has a viscosity in the range of about 10 to 10,000 mPa · s at 25 ° C.

The stoichiometric ratio of the polyol component including all additives to the isocyanate component may be 100: 10 parts by weight. to 100: 200 parts by wt.

The proportion of amine 1 in the polyol component is about 0.25 to 5% by weight, preferably 0.5 to 2% by weight. The proportion of amine 2 in the polyol component is about 0.3 to 5% by weight, preferably 1 to 2% by weight. In view of the desired results, the combination of amine 1 with amine 2 in a ratio of 0.5: 1 to 2: 1 in wt.%, For example in a ratio of 1.5: 1.5 wt.

The amines of the invention are added to the polyol component prior to reaction with the isocyanate component. The polyol component, including all additives, is mechanically blended with the isocyanate component prior to application to the desired surfaces.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

4,4'-methylene-bis- (3-chloro-2,6-diethylaniline) (M-CDEA), a melting point of approximately 85 ° C, marketed by Lonza AG, Basel, is dissolved as amine 2 in of heat in the polyether polyol component. Polyol 1 used is polypropylene glycol having a hydroxyl value of 380 mg KOH / g and a viscosity of 650 mPa.s at 25 ° C. The remaining components, i.e., Desiccant 1, which is comprised of the conventional sodium-potassium aluminosilicate zeolite type A and marketed under the Baylith L Pulver brand from Bayer AG, Leverkusen; diazabicyclooctane, which is marketed as a 33% solution in dipropylene glycol, for example under the trademark Dabco 33 LV from Biesterfeld & Co., Hamburg, as a catalyst; calcium carbonate marketed as chalk under the brand name Omya BLR 2 from Omya, Koln, and 4,4'-diamino-3,3'-dimethylcyclohexylmethane (Laromin C 260) as amine 1, marketed from from BASF, Ludwigshafen, are added to the solution and introduced with a homogenizer

with gears to the dispersion state. degassing exposes to vacuum. The resulting mixture in order to polyol 1 100 ALIGN! G amine 2 6 G

desiccant 1 catalyst calcium carbonate, chalk amine 1

0.05

285 mixture viscosity:

Specific gravity of the mixture:

about 25 Pa.s. about 1.8 kg / l

The mixture thus prepared is mixed with a stoichiometric ratio of 100: 30 in parts by weight with a prepolymer-modified 4,4'-diphenylmethane diisocyanate with polymeric components, specific gravity 1.23 kg / l, NCO content 28% by means of a conventional two-component mixing and dosing device, a viscosity of 250 mPa.s at 25 [deg.] C., which is an isocyanate 1. The result is a thixotropic mass which can be applied to a vertical surface in a layer of 20 mm or more by a flexible hose and which hardens to a hard mass with a hardness approximately D 90 according to Shore.

Example 2

4,4'-methylene-bis- (3-chloro-2,6-diethylaniline) (M-CDEA), a melting point of approximately 85 ° C, marketed by Lonza AG, Basel, is dissolved as amine 2 in of heat in the polyether polyol component. Polyol 2 used is polypropylene glycol having a hydroxyl value of 7 6 mg KOH / g and a viscosity of 900 mPa. at 25 ° C. The remaining ingredients, i.e. desiccant 2, which is a paste-like zeolite in castor oil and marketed under the Baylith L Paste brand by Bayer AG, Leverkusen; butanediol-1,4; diazabicyclooctane, which is marketed as a 33% solution in dipropylene glycol, for example under the trademark Dabco 33 LV from Biesterfeld & Co., Hamburg, as a catalyst; and 4,4'-diamino • ·

3,3'-Dimethyl-cyclohexylmethane (Laromin C 260) as amine 1, commercially available from BASF, Ludwigshafen, is admixed to the solution with a stirrer.

polyol 2 amine 2 desiccant 2 butanediol-1,4 catalyst calcium carbonate, chalk amine 1 viscosity mixture:

Specific gravity of the mixture:

100 g

1.3 g g

G

0.05 g

285 g

1.8 g

1.3 Pa.s at 25 ° C 1.05 kg / l

The mixture thus prepared is mixed with a stoichiometric ratio of 100:60 in parts by weight with a prepolymer-modified diisocyanate having a specific weight of 1.21 kg / l, an NCO content of 25% and a viscosity of 300 mPa.s at 25 [deg.] Using a conventional two-component mixing and dosing device. The result is a thixotropic mass which can be applied to vertical surfaces in a layer of 20 mm or more in a single operation using a flexible hose and which cures to an elastic mass with a Shore hardness of approximately A90.

Claims (13)

PATENT CLAIMS A two-component polyurethane system consisting of a polyol and an isocyanate component which interact exothermically, characterized in that the polyol component contains at least two amines A1 and A2, wherein the reactivity R1 of amine 1 to the isocyanate component is substantially greater than that of R2 amine 2 relative to the isocyanate component, wherein the amine A1 is selected to react within a few seconds with the isocyanate component to give a structural viscosity such that the system still wets the substrate while being stable, and the amine A2 is selected to react with the amine Al with an isocyanate component delayed such that an increased and temperature-stable structural viscosity is obtained. A two-component polyurethane system according to claim 1, characterized in that the ratio of the reactivity R1 of amine 1 to the reactivity R2 of amine 2 relative to the isocyanate component is 1000 to 5. A two-component polyurethane system according to claim 2, characterized in that the ratio of the reactivity R1 of amine 1 to the reactivity R2 of amine 2 relative to the isocyanate component is 100 to 5. A two-component polyurethane system according to claims 1 to 3, characterized in that the amine 1 is selected as the replacement side 14a of aromatic amines (group 1 a), cycloaliphatic amines (group 1 b), araliphatic amines (group 1 c), and aliphatic amines and polyamines (group 1 d). A two-component polyurethane system according to claims 1 to 3, wherein the amine 2 is selected from the group of 2, comprising: methylene-bis- (3-chloro-2, β-diethylaniline) (M-CDEA), 3,5-dimethylthio-2,4- or -2,6-toluylenediamine, replacement side Benzoic acid 3,5-diamino-4-chloro-isobutyl ester (DACB), anthranilic acid methylene-bis-methyl ester (MBMA), 4,4'-diamino-3,3'-dichlorodiphenylmethane (MOCA) and the like. A two-component polyurethane system according to any one of the claims 1 to 5, characterized in that amine 1 is selected from groups 1 a) to 1 d) and amine 2 is selected from 2. A two-component polyurethane system according to any one of claims 1 to 5, characterized in that amine 1 is selected from groups 1 a) to 1 d) and amine 2 is selected from 1 a), wherein the reactivity R1 of amine 1 of groups 1 b) to 1 d) is greater than that of R2 of amine 2 of group 1 a). A two-component polyurethane system according to any one of claims 1 to 7, wherein the amine 1 is 4,4'-diamino-3,3'-dimethyl-cyclohexylmethane and the amine 2 is composed of 4,4'-methylene-bis- (3-chloro-2,6-diethylaniline). A two-component polyurethane system according to any one of claims 1 to 8, wherein the weight ratio of amine 1 to amine 2 is in the range of 0.5: 1 to 2: 1 in% by weight. A two-component polyurethane system according to any one of the claims 1-8, characterized in that the proportion of amine 1 on the polyol component is 0.25 to 5 wt. and an amine fraction 2 on the polyol component is 0.3 to 5 wt. A two-component polyurethane system according to any one of claims 1 to 10, characterized in that the polyol consists of polyether polyols and / or polyester polyols in the molecular weight range of 75 to 6000 and the isocyanate is a 4,4'-diphenylmethane diisocyanate derivative. Process for preparing a two-component polyurethane system according to the preceding claims, characterized in that the amine component is dissolved in the polyol component, the second amine component and the desired additives are added by means of a stirrer and the resulting mixture is mixed with the diisocyanate in a mixing and dosing device. Use of a two-component polyurethane system according to the preceding claims for the production of moldings for Cubing models, early models and the like in the automotive industry and for the production of structured bodies, thick layers and sealing beads.