Silane-terminated adhesive for joining joints in the naval field

Abstract

An adhesive which includes at least one silane-functional polymer P; at least one catalyst for crosslinking silane-functional polymers, the catalyst being selected from the group including organo-titanate, organo-zirconate, and organo-aluminate; at least one base; and at least one adhesive selected from alkoxy mercaptosilane and amino alkoxysilane, for filling wood joints. The adhesive filled into the joints is preferably sanded after the curing process. The adhesive exhibits a high UV stability and a stability against warm humid climates. The adhesive is therefore suitable for naval applications in particular, such as in the construction of boats and ships. The adhesive can be formulated so as to be black, white, or gray for example.

Claims

1. An adhesive comprising at least one silane-functional polymer P; at least one catalyst for the crosslinking of silane-functional polymers, selected from the group consisting of organotitanate, organozirconate, and organoaluminate, wherein an amount of the at least one catalyst is from 0.01% to 10% by weight based on a total weight of the adhesive; at least one base, wherein the at least one base is selected from guanidine, imidazole, imidazoline, bicyclic amidine or from derivatives of these compounds, and wherein an amount of the at least one base is from 0.01% to 3% by weight based on the total weight of the adhesive; and at least one adhesion promoter selected from an alkoxymercaptosilane and an aminoalkoxysilane, wherein an amount of the at least one adhesion promoter is from 0.1% to 7% by weight based on the total weight of the adhesive, for filling wood joints, the wood being natural or synthetic wood, wherein the adhesive is sanded after having been cured, the adhesive is moisture-curing, the adhesive is produced and stored in the absence of moisture, and the adhesive is phthalate-free and comprises no Sn-based catalyst.

2. An adhesive as claimed in claim 1, wherein the cured and sanded adhesive, after 3000 hours in a QUV tester, with 8-fold magnification, shows no cracks, wherein, if the adhesive is white, beige or gray, the color difference delta E between the cured and sanded adhesive before weathering in the QUV tester and after the 3000 hours in the QUV tester is less than 2.

3. An adhesive as claimed in claim 1, wherein the silane-functional polymer P contains no methoxysilane groups.

4. An adhesive as claimed in claim 1, wherein the adhesion promoter is an ethoxymercaptosilane.

5. An adhesive as claimed in claim 1 for marine or limnic applications.

6. An adhesive as claimed in claim 1, wherein the adhesive is black, beige, white or gray.

7. An adhesive as claimed in claim 1, wherein the adhesive has a viscosity in the range from 20 to 1500 Pas at a temperature of 23 C. and a shear rate of 10 s.sup.1.

8. An adhesive as claimed in claim 1, wherein the adhesive exhibits a flow in the vertical U-profile (22.520 cm) of less than 2 cm.

9. An adhesive as claimed in claim 1, wherein the adhesive exhibits shrinkage of less than 5%.

10. A method for grouting a wood joint, the wood being natural or synthetic wood, comprising a) filling the wood joint with an adhesive, b) curing the adhesive in the wood joint, and c) sanding the cured adhesive, where the adhesive comprises the adhesive according to claim 1.

11. The method as claimed in claim 10, the wood joint being part of a marine or limnic article.

12. An adhesive as claimed in claim 1, wherein the at least one adhesion promoter is an alkoxymercaptosilane.

Description

EXAMPLES

Measurement Methods

(1) The viscosity and the flow of the adhesives produced were determined in accordance with the methods described above in the description. The stability was determined in the QUV tester or in the Suntester likewise in accordance with the techniques indicated in the description.

Example 1

Preparation of the Silane-Functional Polymer P

(2) Under a nitrogen atmosphere, 700 g of Acclaim 12200 polyol (Bayer MaterialScience AG, Germany; low monol polyoxypropylenediol; OH number 11.0 mg KOH/g; water content about 0.02 wt %), 32.1 g of isophorone diisocyanate (Vestanat IPDI, Evonik Degussa GmbH, Germany), 85.4 g of 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (Eastman TXIB; Eastman Chemical Company, USA), and 0.4 g of Tyzor IBAY (from DuPont, USA) were heated to 90 C. with continuous stirring, and left at this temperature. After a reaction time of an hour, the free isocyanate group content attained, by titration, was 0.7 wt %. Subsequently 0.14 mol (corresponding to a stoichiometric reaction of the NCO groups with silane) of reactive silane (Int-EtO) was added, and stirring was continued at 90 C. for a further 2 to 3 hours. The reaction was terminated when free isocyanate was no longer detectable by IR spectroscopy (2275-2230 cm.sup.1). The product was cooled to room temperature (23 C.) and kept in the absence of moisture (theoretical polymer content=90%).

(3) The reactive silane Int-EtO (diethyl N-(3-triethoxysilylpropyl)aminosuccinate) was prepared as follows: 100 g of 3-aminopropyltriethoxysilane (Dynasylan AMEO from Evonik Degussa GmbH, Germany) were introduced. Added slowly with thorough stirring at room temperature were 77.8 g of diethyl maleate (Fluka Chemie GmbH, Switzerland), and the mixture was stirred at 60 C. for 12 hours.

(4) Preparation of the Thixotropic Agent TM

(5) A vacuum mixer was charged with 1000 g of diisononyl 1,2-cyclohexanedicarboxylate (DINCH, Hexamoll DINCH, BASF SE, Germany) and 160 g of 4,4-diphenylmethane diisocyanate (Desmodur 44 MC L, Bayer MaterialScience AG, Germany) and this initial charge was gently heated. Then, with vigorous stirring, 90 g of monobutylamine were added slowly dropwise. The white paste which formed was stirred further for an hour under reduced pressure and with cooling. The thixotropic agent TM contains 20 wt % of thixotropic agent in 80 wt % of DINCH.

(6) Production of the Adhesive

(7) In a vacuum mixer, 24 parts by weight of silane-functional polymer P, 7 parts by weight of diisononyl 1,2-cyclohexanedicarboxylate (DINCH, Hexamoll DINCH, BASF SE, Germany), 17 parts by weight of thixotropic agent TM, and 1 part by weight of tetraethoxysilane (Dynasylan A from Evonik Degussa GmbH, Germany) were mixed thoroughly for 5 minutes. Then 46 parts by weight of dried, precipitated chalk (Socal U1S2, Solvay SA, Belgium) and 3 parts by weight of titanium dioxide (Kronos) were incorporated with kneading at 60 C. for 15 minutes. With the heating switched off, 0.5 part by weight of catalyst (Tyzor IBAY, DuPont, USA, a titanium ethylacetoacetate complex), 0.5 part by weight of DBU (1,8-diazabicyclo[5.4.0]undec-7-ene, BASF), 1 part by weight of 3-mercaptopropyltriethoxysilane (Silquest A1891, Momentive) were then processed to a homogeneous paste under reduced pressure for 10 minutes. The adhesive produced was then dispensed into internally coated aluminum gun-application cartridges.

(8) The resulting adhesive is white. The viscosity, the flow in the U-profile, and the stability of the sanded joint in the QUV tester and in the Suntester were investigated. The results obtained were as follows:

(9) Viscosity (23 C.): 300 Pas

(10) Flow in the U-profile: 0.2 cm

(11) Delta E after 3000 h in the Suntester or QUV tester: 1.5

(12) No cracking in the sanded joint after 3000 h in the Suntester or QUV tester

Example 2

(13) The production of the adhesive as in example 1 was repeated, except that 3 parts by weight of gray pigment were used rather than 3 parts by weight of titanium dioxide. In this way a gray adhesive was obtained. The tests from example 1 were repeated. The results obtained were as follows:

(14) Viscosity (23 C.): 300 Pas

(15) Flow in the U-profile: 0.3 cm

(16) Delta E after 3000 h in the Suntester or QUV tester: 1.8

(17) No cracking in the sanded joint after 3000 h in the Suntester or QUV tester

Example 3

(18) The production of the adhesive as in example 1 was repeated, except that 3 parts by weight of carbon black were used rather than 3 parts by weight of titanium dioxide. In this way a black adhesive was obtained. The tests from example 1 were repeated, but delta E was not determined, since it is irrelevant for black materials. The results obtained were as follows:

(19) Viscosity (23 C.): 400 Pas

(20) Flow in the U-profile: 0.1 cm

(21) No cracking in the sanded joint after 3000 h in the Suntester or QUV tester

Comparative Example 1

(22) A commercially customary adhesive based on aliphatic polyurethane was investigated in the same way as the examples above, and the results obtained were as follows:

(23) Viscosity (23 C.): 300 Pas

(24) Flow in the U-profile: 0.2 cm

(25) Delta E after 3000 h in the Suntester or QUV tester: 3

(26) Cracking in the sanded joint after 3000 h in the Suntester or QUV tester; initial cracks were observed after just 500 h.

Comparative Example 2

(27) A commercially customary adhesive based on a silane-terminated polymer was investigated in the same way as the examples above, and the results obtained were as follows:

(28) Viscosity (23 C.): 300 Pas

(29) Flow in the U-profile: 0.5 cm

(30) Delta E after 3000 h in the Suntester or QUV tester: 2

(31) Cracking in the sanded joint after 3000 h in the Suntester or QUV tester; initial cracks were observed after just 1000 h.

Comparative Example 3

(32) The production of the adhesive in accordance with example 1 was repeated, except that the 24 parts by weight of silane-functional polymer P were replaced by 24 parts by weight of polymer ST 77 (commercial product from Evonik Hanse, methoxysilane-functional polyurethane polymer), 0.5 part by weight of Tyzor BAY was replaced by 0.5 part by weight of DBTDL (10% strength solution of dibutyltin dilaurate in diisooctyl phthalate) as catalyst, and no DBU was used. In this way a white adhesive was obtained. The tests from example 1 were repeated. The results obtained were as follows:

(33) Viscosity (23 C.): 300 Pas

(34) Flow in the U-profile: 0.2 cm

(35) Delta E after 3000 h in the Suntester or QUV tester: 2

(36) Cracking in the sanded joint after 3000 h in the Suntester or QUV tester; initial cracks were observed after just 1000 h.

Comparative Example 4

(37) The production of the adhesive as in example 1 was repeated, except that DBU was omitted and replaced by an additional 0.5 part by weight of DINCH. In this way a white adhesive was obtained. The tests from example 1 were repeated. The results obtained were as follows:

(38) Viscosity (23 C.): 300 Pas

(39) Flow in the U-profile: 0.3 cm

(40) Delta E after 3000 h in the Suntester or QUV tester: 1.9

(41) Cracking in the sanded joint after 3000 h in the Suntester or QUV tester; even during sanding, a slightly nonuniform surface was observed and the joint appeared to be very soft. Initial cracks were observed after 1000 h.