DISPERSION ADHESIVES

Abstract

The invention relates to formulations of aqueous dispersion adhesives on the basis of aqueous polyurethane or polyurethane-urea dispersions and the use of the adhesive formulations for bonding foam substrates according to the spray coagulation method.

Claims

1. Formulations containing a mixture of I. an aqueous polyurethane or polyurethane-urea dispersion, containing as disperse phase a polymer A) which after drying is semicrystalline or crystalline and has a melting temperature in a range from 30 to 80° C. and an enthalpy of fusion of ≥35 J/g, II. at least one plasticizer resin B), III. at least one tackifier resin C), wherein the mixture, based on the solids present overall, contains 60%-90% by weight of polymer A), 5%-20% by weight of plasticizer resin B) and 5%-20% by weight of tackifier resin C), and the amounts by weight of A), B) and C) add up to 100% by weight.

2. The formulations as claimed in claim 1, wherein the mixture, based on the solids present overall, contains 66%-85% by weight of polymer A), 8%-18% by weight of plasticizer resin B) and 7%-16% by weight of tackifier resin C), and the amounts by weight of A), B) and C) add up to 100% by weight.

3. The formulations as claimed in claim 1, wherein the mixture, based on the solids present overall, contains 70%-81% by weight of polymer A), 10%-16% by weight of plasticizer resin B) and 9%-14% by weight of tackifier resin C), and the amounts by weight of A), B) and C) add up to 100% by weight.

4. The formulations as claimed in claim 1, wherein the mixture, based on the solids present overall, contains 72%-80% by weight of polymer A), 10%-15.5% by weight of plasticizer resin B) and 10%-12.5% by weight of tackifier resin C), and the amounts by weight of A), B) and C) add up to 100% by weight.

5. The formulations as claimed in claim 1, wherein the polymer A) which after drying is semicrystalline or crystalline has a melting temperature in the range from 35° C. to 80° C., particularly preferably in the range from 40° C. to 70° C. and very particularly preferably in the range from 42° C. to 55° C.

6. The formulations as claimed in claim 1, wherein the polymer A) which after drying is semicrystalline or crystalline has an enthalpy of fusion of ≥35 J/g, preferably ≥40 J/g, particularly preferably ≥45 J/g.

7. The formulations as claimed in claim 1, wherein, as the plasticizer B), use is made of non-volatile, low molecular weight compounds bearing polar groups, preferably di(phenoxyethyl) formal, dibutyl terephthalate, alkylsulfonic esters of phenol and esters based on benzoic acid.

8. The formulations as claimed in claim 1, wherein, as tackifier resins C), use is made of rosins and modified rosins, preferably resin esters based on rosin and particularly preferably aqueous dispersions of rosin esters (rosin ester dispersions),

9. A process for adhesively bonding substrates by mixing a formulation as claimed in claim 1 with a coagulant in a two-component spray gun, wherein the coagulant is conveyed separately into the two-component spray gun and is mixed in a spray jet and the coagulation of the dispersion in the spray jet takes place on a path to a surface of a first substrate, on impact with said substrate forms a film which is immediately tacky in a still-wet state and in the wet state a second surface is immediately joined, if required with pressure on the substrates towards an adhesive surface.

10. The use of the formulations as claimed in claim 1 for bonding of foam on foam, foam on wood, foam on plastics, and of textiles on various substrates.

11. The use as claimed in claim 10, wherein at least one of the substrates to be adhesively bonded is a nonpolar substrate, in particular is filled or unfilled polypropylene.

12. The use as claimed in claim 10, wherein at least one of the substrates to be adhesively bonded is a foam substrate comprising polyurethane (for example polyether and polyester foams), foam rubber (for example formed from natural rubber (NR), styrene-butadiene rubber (SBR), ethylene-propylene-diene polymer (EPDM), butadiene-acrylonitrile rubber (NBR) or chloroprene rubber (CR)).

13. An item of furniture, produced using the formulations as claimed in claim 1.

Description

EXAMPLES

[0100] The invention will be elucidated in more detail below on the basis of the examples. The following methods and test methods were used here:

[0101] A) Spray Coagulation Process:

[0102] A standard spray gun for two-component dispersion adhesives, namely the PILOT III 2K from Walther Pilot, is used for application. The adhesive and the coagulant CaCl.sub.2) (3% by weight solution in water) are conveyed separately into the spray gun, mixed in the spray jet and the adhesive is coagulated. As the mixing does not take place until in the spray jet, no pot life needs to be taken into account. A ratio of 86% by weight adhesive dispersion and 14% by weight CaCl.sub.2) solution was chosen.

[0103] The precise settings of the spray gun are known in principle to the person skilled in the art and can be tailored to the specific case without undue burden and determined by simple preliminary experiments. The quantitative ratios and the application weight can be determined by reweighing the reservoir vessel and the substrates.

[0104] The following settings were used: [0105] a.) Adhesive component: conveying pressure 1.3 bar [0106] b.) Coagulation component: conveying pressure 0.3 bar [0107] c.) Atomizer air pressure: 2.8 bar [0108] d.) Bore diameter (nozzle) for adhesive component: 1.0 mm [0109] e.) Bore diameter (nozzle) for coagulant component: 0.4 mm [0110] f.) Application weights: 130-150 g/m.sup.2 (wet)

[0111] B) Determination of the Initial Strength for Foam Substrates Having a High Foam Density and High Restoring Force:

[0112] As test material, ST 13070 PU foam bodies from STN Schaumstoff Technik Nurnberg GmbH having the dimensions 10×5×3 cm and a foam density of 70 kg/m.sup.3 are used. To assess the initial strength, immediately after application of the adhesive by means of the spray coagulation process (application rate 130-150 g/m.sup.2 wet), the test specimens are folded in the middle using light palm pressure and joined together. The initial strength is sufficient if the test specimen does not open up in spite of the restoring forces arising.

[0113] C) Adhesion to Polypropylene (Adhesive Bonding of Foam Substrates to Polypropylene Substrates):

[0114] As test material, Recticel® T 20120 PU foam bodies from Recticel having a foam density of 20 kg/m.sup.3 and the dimensions 10×5×3 cm (FIG. 1, (A)) and PP-DWST polypropylene plastics substrates from SIMONA AG having the dimensions 20×10×0.4 cm (FIG. 1, (B)) are used. Adhesive is applied by means of the spray coagulation process (application rate 130-150 g/m.sup.2 wet) in the case of the polypropylene substrate to the entire surface of the top side (20×10 cm) (FIG. 1, (B.sub.O)) and in the case of the foam substrate to the entire surface of the bottom side (10×5 cm) (FIG. 1, (C)) and additionally to a short edge face (5×3 cm) (FIG. 1, (D)).

[0115] After application of the adhesive, the foam is joined to the polypropylene. For this purpose, the surface (C), which has been provided with adhesive, of the foam is joined to the side, which has had adhesive applied, of the polypropylene by hand with slight pressure (FIG. 1, (C) against (B.sub.o)). Then, the edge face, which has been provided with adhesive, of the foam (FIG. 1.1, (D)) is likewise joined by hand with slight pressure (FIG. 1.1, (F)) to the coated side of the polypropylene (FIG. 1.2, (D)), so that the foam test specimen is under high strain in the region of the joined edge face (D) and the surface (A) as a result of the restoring force (FIG. 1.2, (FR)).

[0116] The adhesion is assessed after storage of the test specimen for 24 hours at room temperature: If the joined edge face (FIG. 1.2, (D)) of the foam substrate (FIG. 1.2, (A)) detaches again from the surface (FIG. 1.2 (B.sub.O)) of the polypropylene substrate (FIG. 1, (B)) immediately in the wet state, or during or after drying, no sufficient adhesion is present.

[0117] D) Ascertaining the Glass Transition Temperatures, Melting Temperatures and Enthalpies of Fusion by Means of DSC:

[0118] The glass transition temperatures and also melting temperatures and enthalpies of fusion were determined by means of differential scanning calorimetry (DSC) using a Pyris Diamond DSC calorimeter from Perkin-Elmer. To this end, a film was produced by knife coating the dispersion onto a glass sheet at a 100 μm wet film thickness, flashed off for 2 hours, and then this film together with the glass sheet is dried in a dry box for 3 days at room temperature and 0% relative room humidity. Then, using 10 mg of sample material from this film, the DSC curve is recorded with the following measurement conditions: Rapid cooling to the starting temperature −100° C., then commencement of three heatings from −100° C. to +150° C. at a heating rate of 20 K/min and a cooling rate of 320 K/min under a helium atmosphere and with cooling with liquid nitrogen. The glass transition temperature corresponds to the temperature at half the height of the glass transition, with the third heating being assessed. For determination of the melting temperatures and enthalpies of fusion, the first heating was assessed.

[0119] E) Feedstocks [0120] Polyester I: polyester diol formed from butane-1,4-diol and adipic acid having an OH number=50 [0121] Polyester II: polyester diol formed from hexane-1,6-diol and phthalic anhydride having an OH number=56 [0122] Desmodur® H: hexamethylene 1,6-diisocyanate (Covestro Deutschland AG, Leverkusen/Germany) [0123] Desmodur® I: isophorone diisocyanate (Covestro Deutschland AG, Leverkusen/Germany) [0124] Luphen® DDS 3548: epoxy resin-modified polyurethane dispersion from BASF AG, Ludwigshafen/Germany, having a solids content of 45% by weight. The polymer present is semicrystalline after drying with a melting temperature of 41.5° C. and an enthalpy of fusion of 34.4 J/g. [0125] Desavin®: di(phenoxyethyl) formal (Covestro Deutschland AG, Leverkusen/Germany) (plasticizer resin) [0126] DBT: di-n-butyl terephthalate (Eastman, Kingsport/US) (plasticizer resin) [0127] Synegis® 9100: dipropylene glycol dibenzoate (Synegis, Mont-Saint-Guibert/Belgium) (plasticizer resin) [0128] Aquatac® XR-4343: aqueous rosin ester dispersion having 60% by weight solids content (Kraton Corporation, Almere/the Netherlands) (tackifier resin)

Example 1

[0129] Preparation of an aqueous polyurethane or polyurethane-urea dispersion.

[0130] 450 g of polyester I are dewatered for 1 hour at 110° C. and 15 mbar. At 80° C., 30.11 g of Desmodur® H and then 20.14 g of Desmodur® I are added. The mixture is stirred at 80 to 90° C. until a constant isocyanate content of 1.15% by weight has been reached. The reaction mixture is dissolved in 750 g of acetone and cooled to 48° C. Into the homogeneous solution is added a solution of 5.95 g of the sodium salt of N-(2-aminoethyl)-2-aminoethanesulfonic acid and 2.57 g of diethanolamine in 65 g of water with vigorous stirring. After 30 minutes, the mixture is dispersed by addition of 700 g of water. Distillative removal of the acetone affords an aqueous polyurethane-polyurea dispersion having a solids content of 40.0% by weight.

[0131] The polymer present is semicrystalline after drying with a melting temperature of 48° C. and an enthalpy of fusion of 50.4 J/g.

Example 2

[0132] Preparation of an aqueous polyurethane or polyurethane-urea dispersion.

[0133] 798.3 g of polyester I are dewatered for 1 hour at 110° C. and 15 mbar. Then, at 80° C., 13.5 g of butane-1,4-diol and 157.0 g of Desmodur® I are added and the mixture is stirred at 90 to 100° C. until a constant isocyanate content of 1.72% has been reached. The reaction mixture is dissolved in 1450 g of acetone and cooled to 48° C. Into the homogeneous solution is added a solution of 16.5 g of the sodium salt of N-(2-aminoethyl)-2-aminoethanesulfonic acid and 7.7 g of diethanolamine in 195 g of water with stirring, and the mixture is stirred at 48° C. for a further 30 minutes. The mixture is then dispersed by addition of 1440 g of water with vigorous stirring. Distillative removal of the acetone affords an aqueous polyurethane-polyurea dispersion having a solids content of 38.0% by weight.

[0134] The polymer present is semicrystalline after drying with a melting temperature of 49.8° C. and an enthalpy of fusion of 45.9 J/g.

Example 3

[0135] Preparation of an aqueous polyurethane or polyurethane-urea dispersion.

[0136] 1215 g of polyester II are dewatered for 1 hour at 110° C. and 15 mbar. At 80° C., 4.6 g of hexane-1,6-diol and 179.0 g of Desmodur® H are added and the mixture is stirred at 90° C. until a constant isocyanate content of 2.28% by weight has been reached. The reaction mixture is dissolved in 2490 g of acetone and cooled to 48° C. Into the homogeneous solution is added a solution of 31.9 g of the sodium salt of N-(2-aminoethyl)-2-aminoethanesulfonic acid in 300 g of water with vigorous stirring. After 30 minutes, the mixture is dispersed by addition of 1150 g of water. Distillative removal of the acetone affords an aqueous polyurethane-polyurea dispersion having a solids content of 50.0% by weight.

[0137] The polymer present is amorphous after drying (does not have a melting peak in DSC).

Example 4: (Comparison)

[0138] Determination of the initial strength and the adhesion to polypropylene with the dispersion from example 1: the adhesion to polypropylene is insufficient (see table 1).

Example 5: (Comparison)

[0139] Preparation of a formulation formed from the PUD from Example 1 and a tackifier resin dispersion, and determination of the initial strength and the adhesion to polypropylene.

[0140] To 91.7 g of the polyurethane dispersion from Example 1 are added 8.3 g of Aquatac® XR-4343 with vigorous stirring using a disk stirrer, the mixture is stirred for a further 4 h and subsequently stored for 12 h at room temperature. Based on the solids content, the formulation contains 88.0% by weight of polyurethane polymer and 12.0% by weight of tackifier resin.

[0141] The initial strength and the adhesion to polypropylene are determined with the formulation: the adhesion to polypropylene is insufficient (see table 1).

Example 6: (Comparison)

[0142] Preparation of a formulation formed from the PUD from Example 1 and a plasticizer resin, and determination of the initial strength and the adhesion to polypropylene.

[0143] To 92.7 g of the polyurethane dispersion from Example 1 are added 7.3 g of Desavin® with vigorous stirring using a disk stirrer, the mixture is stirred for a further 4 h and subsequently stored for 12 h at room temperature. Based on the solids content, the formulation contains 83.6% by weight of polyurethane polymer and 16.4% by weight of plasticizer resin.

[0144] The initial strength and the adhesion to polypropylene are determined with the formulation: the adhesion to polypropylene is insufficient (see table 1).

Example 7: (Comparison)

[0145] Preparation of a formulation formed from the PUD from Example 1 and a plasticizer resin, and determination of the initial strength and the adhesion to polypropylene.

[0146] To 93.5 g of the polyurethane dispersion from Example 1 are added 6.5 g of Synegis® 9100 with vigorous stirring using a disk stirrer, the mixture is stirred for a further 4 h and subsequently stored for 12 h at room temperature. Based on the solids content, the formulation contains 85.2% by weight of polyurethane polymer and 14.8% by weight of plasticizer resin.

[0147] The initial strength and the adhesion to polypropylene are determined with the formulation: the adhesion to polypropylene is insufficient (see table 1).

Example 8: (According to the Invention)

[0148] Preparation of a formulation formed from the PUD from Example 1, a tackifier resin and a plasticizer resin, and determination of the initial strength and the adhesion to polypropylene.

[0149] To 85.6 g of the polyurethane dispersion from Example 1 are added in succession 7.7 g of Aquatac® XR-4343 and 6.7 g of Desavin® with vigorous stirring using a disk stirrer, the mixture is stirred for a further 4 h and subsequently stored for 12 h at room temperature. Based on the solids content, the formulation contains 75.2% by weight of polyurethane polymer, 10.1% by weight of tackifier resin and 14.7% by weight of plasticizer resin.

[0150] The initial strength and the adhesion to polypropylene are determined with the formulation: both the initial strength and the adhesion to polypropylene are good (see table 1).

Example 9: (According to the Invention)

[0151] Preparation of a formulation formed from the PUD from Example 1, a tackifier resin and a plasticizer resin, and determination of the initial strength and the adhesion to polypropylene.

[0152] To 85.6 g of the polyurethane dispersion from Example 1 are added in succession 7.7 g of Aquatac® XR-4343 and 6.7 g of DBT with vigorous stirring using a disk stirrer, the mixture is stirred for a further 4 h and subsequently stored for 12 h at room temperature. Based on the solids content, the formulation contains 75.2% by weight of polyurethane polymer, 10.1% by weight of tackifier resin and 14.7% by weight of plasticizer resin.

[0153] The initial strength and the adhesion to polypropylene are determined with the formulation: both the initial strength and the adhesion to polypropylene are good (see table 1).

Example 10: (According to the Invention)

[0154] Preparation of a formulation formed from the PUD from Example 1, a tackifier resin and a plasticizer resin, and determination of the initial strength and the adhesion to polypropylene.

[0155] To 84.0 g of the polyurethane dispersion from Example 1 are added in succession 9.0 g of Aquatac® XR-4343 and 7.0 g of Synegis® 9100 with vigorous stirring using a disk stirrer, the mixture is stirred for a further 4 h and subsequently stored for 12 h at room temperature. Based on the solids content, the formulation contains 73.0% by weight of polyurethane polymer, 11.7% by weight of tackifier resin and 15.2% by weight of plasticizer resin.

[0156] The initial strength and the adhesion to polypropylene are determined with the formulation: both the initial strength and the adhesion to polypropylene are good (see table 1).

Example 11: (According to the Invention)

[0157] Preparation of a formulation formed from the PUD from Example 2, a tackifier resin and a plasticizer resin, and determination of the initial strength and the adhesion to polypropylene.

[0158] To 87.0 g of the polyurethane dispersion from Example 2 are added in succession 8.7 g of Aquatac® XR-4343 and 4.3 g of Desavin® with vigorous stirring using a disk stirrer, the mixture is stirred for a further 4 h and subsequently stored for 12 h at room temperature. Based on the solids content, the formulation contains 77.6% by weight of polyurethane polymer, 12.3% by weight of tackifier resin and 10.1% by weight of plasticizer resin.

[0159] The initial strength and the adhesion to polypropylene are determined with the formulation: both the initial strength and the adhesion to polypropylene are good (see table 1).

Example 12: (Comparison)

[0160] Preparation of a formulation formed from the PUD from Example 1, a tackifier resin and a plasticizer resin, and determination of the initial strength and the adhesion to polypropylene.

[0161] To 78.0 g of the polyurethane dispersion from Example 1 are added in succession 9.0 g of Aquatac® XR-4343 and 13.0 g of Synegis® 9100 with vigorous stirring using a disk stirrer, the mixture is stirred for a further 4 h and subsequently stored for 12 h at room temperature. Based on the solids content, the formulation contains 62.9% by weight of polyurethane polymer, 10.9% by weight of tackifier resin and 26.2% by weight of plasticizer resin.

[0162] The initial strength and the adhesion to polypropylene are determined with the formulation: the adhesion to polypropylene is insufficient (see table 1).

Example 13: (Comparison)

[0163] Determination of the initial strength and the adhesion to polypropylene with the dispersion from example 3: both the initial strength and the adhesion to polypropylene are insufficient (see table 1).

Example 14: (Comparison)

[0164] Preparation of a formulation formed from the PUD from Example 3, a tackifier resin and a plasticizer resin, and determination of the initial strength and the adhesion to polypropylene.

[0165] To 82.7 g of the polyurethane dispersion from Example 3 are added in succession 9.3 g of Aquatac® XR-4343 and 5.0 g of Desavin® with vigorous stirring using a disk stirrer, the mixture is stirred for a further 4 h and subsequently stored for 12 h at room temperature. Based on the solids content, the formulation contains 79.6% by weight of polyurethane polymer, 11.8% by weight of tackifier resin and 9.6% by weight of plasticizer resin.

[0166] The initial strength and the adhesion to polypropylene are determined with the formulation: both the initial strength and the adhesion to polypropylene are insufficient (see table 1).

Example 15: (Comparison)

[0167] Determination of the initial strength and the adhesion to polypropylene with Luphen® DDS 3548: both the initial strength and the adhesion to polypropylene are insufficient (see table 1).

Example 16: (Comparison)

[0168] Preparation of a formulation formed from Luphen® DDS 3548, a tackifier resin and a plasticizer resin, and determination of the initial strength and the adhesion to polypropylene.

[0169] To 83.9 g of Luphen® DDS 3548 are added in succession 8.6 g of Aquatac® XR-4343 and 7.5 g of Desavin® with vigorous stirring using a disk stirrer, the mixture is stirred for a further 4 h and subsequently stored for 12 h at room temperature. Based on the solids content, the formulation contains 74.9% by weight of the Luphen® DDS 3548 polymer, 10.2% by weight of tackifier resin and 14.9% by weight of plasticizer resin.

[0170] The initial strength and the adhesion to polypropylene are determined with the formulation: both the initial strength and the adhesion to polypropylene are insufficient (see table 1).

TABLE-US-00001 TABLE 1 Evaluation of the examples according to the invention and the comparative examples Initial strength Adhesion to (test PP (test Example Composition method B) method C) 4 PUD from ex. 1 yes no (comparison) 5 PUD from ex. 1, yes no (comparison) Aquatac ® XR-4343 6 PUD from ex. 1 yes no (comparison) Desavin ® 7 PUD from ex. 1 yes no (comparison) Synegis ® 9100 8 PUD from ex. 1, yes yes (according to Aquatac ® XR-4343, the invention) Desavin ® 9 PUD from ex. 1, yes yes (according to Aquatac ® XR-4343, the invention) DBT 10 PUD from ex. 1, yes yes (according to Aquatac ® XR-4343, the invention) Synegis ® 9100 11 PUD from ex. 2, yes yes (according to Aquatac ® XR-4343, the invention) Desavin ® 12 PUD from ex. 1, yes no (comparison) Aquatac ® XR-4343, Synegis 200 9100 13 PUD from ex. 3 no no (comparison) 14 PUD from ex. 3, no no (comparison) Aquatac ® XR-4343, Desavin ® 15 Luphen ® DDS 3548 no no (comparison) 16 Luphen ® DDS 3548, no no (comparison) Aquatac ® XR-4343, Desavin ®