Aqueous-based polychloroprene contact adhesive

Abstract

Aqueous-based adhesive composition comprising a mixture of polycholorprenes, at least one self-crosslinkable agent of alkyd type and at least one filler, 2) use of such a composition as contact adhesive, 3) multilayer structure assembled with the aid of the adhesive composition 1).

Claims

1. An adhesive composition comprising: A) from 5 to 40% by dry weight, relative to total dry weight of the adhesive composition, of a mixture of polychloroprenes comprising: A1) at least one polychloroprene having a hardness greater than or equal to 80 Shore A; and A2) at least one polychloroprene having a hardness less than or equal to 60 Shore A; B) from 0.5 to 25% by dry weight, relative to total dry weight of the adhesive composition, of at least one self-crosslinkable agent of alkyd type, wherein the at least one self-crosslinkable agent of alkyd type comprises: (i) at least one alkyd resin comprising at least one 5-membered cyclocarbonate function (Y), and (ii) at least one alkyd resin comprising at least one primary amine function (X) salified by an acid having a pKa ranging from 1 to 14, and having a carbon-based chain comprising from 1 to 6 carbon atoms; C) from 10 to 40% by dry weight, relative to total dry weight of the adhesive composition, of at least one mineral filler; D) from 0.05 to 3% by dry weight, relative to total dry weight of the adhesive composition, of at least one emulsifier; and E) water in which said mixture of polychloroprenes is dispersed.

2. The adhesive composition of claim 1, wherein the mixture of polychloroprenes comprises: A1) at least one polychloroprene in aqueous dispersion having a hardness greater than or equal to 85 Shore A, and/or A2) at least one polychloroprene in aqueous dispersion having a hardness less than or equal to 55 Shore A.

3. The adhesive composition of claim 1, wherein the at least one mineral filler is selected from the group consisting of calcium carbonate, silica, a composite based on silica and kaolinite, sepiolite, and a mixture thereof.

4. The adhesive composition of claim 1, wherein the at least one emulsifier comprises a system of at least two emulsifiers selected from the group consisting of the following emulsifiers: oxyethylenated unsaturated acyclic fatty alcohols having an HLB ranging from 15 to 18; oxyethylenated unsaturated cyclic fatty alcohols having a cloud point ranging from 63 to 67 C.; mixtures of mono- and dialkylphenoxybenzenedisulfonate salts comprising a linear or branched alkyl portion having from 10 to 14 carbon atoms; oxyethylenated sulfosuccinic acid and alcohol hemiester salts comprising from 10 to 14 carbon atoms; oxyethylenated alkyl ether sulfate salts comprising a linear or branched alkyl portion having from 12 to 14 carbon atoms; and polyvinyl alcohols.

5. The adhesive composition of claim 1, further comprising: at least one metal oxide; at least one adhesion agent selected from the group consisting of copolymers of styrene and (meth)acrylic acid, copolymers of styrene and (meth)acrylic acid ester, copolymers of styrene and (meth)acrylamide, homopolymers and copolymers of butadiene, vinyl acetate polymers, polyurethanes obtained from at least one polyol and at least one polyisocyanate, and mixtures comprising at least one polyurethane obtained from at least one polyol and at least one polyisocyanate and at least one polyester obtained by polycondensation between at least one polyol and at least one polyacid; at least one tackifying resin; at least one thickener; at least one polyvinyl chloride; and/or at least one aqueous dispersion of silica nanoparticles.

6. The adhesive composition of claim 5, wherein the at least one metal oxide is ZnO.

7. The adhesive composition of claim 1, wherein the adhesive composition has a viscosity ranging from 30,000 to 120,000 mPas, measured at 23 C.

8. A multilayer structure comprising at least two identical or different layers of material bonded to one another by a layer of the adhesive composition of claim 1.

9. An adhesive composition comprising: A) from 5 to 40% by dry weight, relative to total dry weight of the adhesive composition, of a mixture of polychloroprenes comprising: A1) at least one polychloroprene having a hardness greater than or equal to 80 Shore A; and A2) at least one polychloroprene having a hardness less than or equal to 60 Shore A; B) from 0.5 to 25% by dry weight, relative to total dry weight of the adhesive composition, of at least one self-crosslinkable agent of alkyd type; C) from 10 to 40% by dry weight, relative to total dry weight of the adhesive composition, of at least one mineral filler; D) from 0.05 to 3% by dry weight, relative to total dry weight of the adhesive composition, of at least one emulsifier; wherein the at least one emulsifier comprises a system of at least two emulsifiers selected from the group consisting of the following emulsifiers: oxyethylenated unsaturated acyclic fatty alcohols having an HLB ranging from 15 to 18; oxyethylenated unsaturated cyclic fatty alcohols having a cloud point ranging from 63 to 67 C.; mixtures of mono- and dialkylphenoxybenzenedisulfonate salts comprising a linear or branched alkyl portion having from 10 to 14 carbon atoms; oxyethylenated sulfosuccinic acid and alcohol hemiester salts comprising from 10 to 14 carbon atoms; oxyethylenated alkyl ether sulfate salts comprising a linear or branched alkyl portion having from 12 to 14 carbon atoms; and polyvinyl alcohols; and has been substituted with E) water in which said mixture of polychloroprenes is dispersed.

10. The adhesive composition of claim 9, wherein the mixture of polychloroprenes comprise: A1) at least one polychloroprene in aqueous dispersion having a hardness greater than or equal to 85 Shore A, and/or A2) at least one polychloroprene in aqueous dispersion having a hardness less than or equal to 55 Shore A.

11. The adhesive composition of claim 9, wherein the at least one mineral filler is selected from the group consisting of calcium carbonate, silica, a composite based on silica and kaolinite, sepiolite, and a mixture thereof.

12. The adhesive composition of claim 9, further comprising: at least one metal oxide; at least one adhesion agent selected from the group consisting of copolymers of styrene and (meth)acrylic acid, copolymers of styrene and (meth)acrylic acid ester, copolymers of styrene and (meth)acrylamide, homopolymers and copolymers of butadiene, vinyl acetate polymers, polyurethanes obtained from at least one polyol and at least one polyisocyanate, and mixtures comprising at least one polyurethane obtained from at least one polyol and at least one polyisocyanate and at least one polyester obtained by polycondensation between at least one polyol and at least one polyacid; at least one tackifying resin; at least one thickener; at least one polyvinyl chloride; and/or at least one aqueous dispersion of silica nanoparticles.

13. The adhesive composition of claim 12, wherein the at least one metal oxide is ZnO.

14. The adhesive composition of claim 9, wherein the adhesive composition has a viscosity ranging from 30,000 to 120,000 mPas, measured at 23 C.

15. A multilayer structure comprising at least two identical or different layers of material bonded to one another by a layer of the adhesive composition of claim 9.

Description

EXAMPLES OF THE INVENTION

(1) The compositions of examples 1 to 10 according to the invention are prepared from the different ingredients indicated in table 1, by mixing the ingredients one by one in a mixer and by adding the fillers and the thickener last.

(2) The contents indicated in table 1 are expressed as % by weight of dry ingredients relative to the total weight of the composition.

(3) Each composition is then subjected to the tests described below.

(4) Neoprene aqueous-based contact adhesives sold under the name Cege100 contact by Cegecol (comprising approximately 5% by weight of filler) (C2) and Uzin Wk 222 by Uzin (comprising approximately 22% by weight of filler) (C1) are tested under the same conditions as the adhesive compositions of examples 1 to 10 according to the invention.

(5) 1/ Evaluation of the Drying Time

(6) For these tests, a laminated wood support, which is approximately 30 cm long, 30 cm wide and 1.5 mm thick, and a standard CTBS agglomerated wood support, which is approximately 30 cm long, 30 cm wide and 3 cm thick, were used.

(7) The adhesive composition is applied to the wood surface (back) of the laminated support and the surface of the standard CTBS agglomerated wood support by means of a standardized notched spatula, making it possible to deposit approximately 200 g/m.sup.2 of composition on each surface of the supports.

(8) The supports coated with adhesive are left to dry in the open air at 20 C. in a humid environment at 65% relative humidity.

(9) The drying time on the support is evaluated qualitatively by regularly exerting a small amount of pressure on the lines of adhesive by means of a finger or paper. The adhesive is estimated to be dry when there is no transfer of adhesive onto the finger or the paper.

(10) The drying times observed on the agglomerated support are shorter than the drying times observed on the laminated support, due to the greater porosity of the agglomerated support.

(11) Only the drying time results on the laminated support were therefore retained and recorded in table 2 below. The results are expressed in minutes.

(12) 2/ Evaluation of the Mechanical Properties by Shear Strength

(13) Unless indicated otherwise in the present application, the preparation of the test specimens and the tensile shear strength tests were carried out in accordance with standard ISO 4587:2003, using a Zwick Z020 dynamometer (exerting a vertical pulling force at a constant rate of 500 meters per second).

(14) For these tests, a beech test specimen, which is 10 cm long, 2.5 cm wide and 3 mm thick, and a laminated wood test specimen with the same dimensions (length, width and thickness), are used.

(15) The adhesive composition is applied by double adhesive coating on the two test specimens by means of a standardized notched spatula, making it possible to deposit approximately 200 g/m.sup.2 of composition on each surface of the test specimens. The adhesive composition is applied to one of the ends of each test specimen over an adhesive bonding zone 2.5 cm long and 2.5 cm wide.

(16) Once they are coated with adhesive, the test specimens are left to dry in the open air at 20 C. in an environment having a level of humidity of between 55% and 65% relative humidity.

(17) When the adhesive is dry, the two test specimens are assembled at the adhesively coated zone, then clamped by means of a clamping bench until the time t at which the test specimens are pulled.

(18) The increase in cohesion of the adhesive composition is evaluated by measuring, at different times t (2 hours, 24 hours and 7 days, respectively, after adhesive coating), the strength of the adhesive joint subjected to a shearing stress.

(19) The results are expressed as kilograms per centimeter squared and are recorded in table 2 below.

(20) 3/ Evaluation of the Heat Resistance

(21) This test is carried out in order to evaluate the heat resistance of the adhesive bond when the adhesively bonded assembly is stressed in terms of temperature.

(22) For these tests, a beech test specimen, which is 10 cm long, 2.5 cm wide and 3 mm thick, and a laminated wood test specimen with the same dimensions (length, width and thickness), are used.

(23) The adhesive composition is applied to one of the ends of each test specimen over an adhesive bonding zone 2.5 cm long and 2.5 cm wide.

(24) Once they are coated with adhesive, the test specimens are left to dry in the open air at 20 C. in an environment having a level of humidity of between 55% and 65% relative humidity.

(25) The adhesive composition is applied by double adhesive coating on the two test specimens by means of a standardized notched spatula, making it possible to deposit approximately 200 g/m.sup.2 of composition on each surface of the test specimens.

(26) When the adhesive is dry, the two supports are assembled then clamped by means of a clamping bench. The assembly is left in the open air for 14 days at 20 C. in an environment having a level of humidity of between 55% and 65% relative humidity. The test specimens are then introduced into an oven, regulated at 23 C., and a 5 kg weight is attached to the end of one of the test specimens, perpendicular to the plane of the adhesive bond. A temperature gradient is applied in the oven, with a rise in temperature of 4.5 C. per minute, and the temperature at which the adhesively bonded assembly yields under the effect of the weight is observed.

(27) The results are expressed as degrees Celsius and are recorded in table 2 below.

(28) 4/ Quality of the Initial Hold

(29) For these tests, the same supports are used as for the test for evaluation of the drying time. The coating is carried out in the same way and under the same conditions as for the test for evaluation of the drying time. The test specimens are then superposed at their coated surface, leaving a 2 cm edge overhanging in order to facilitate gripping at the time of the detachment test.

(30) Immediately after having joined the adhesively coated test specimens by manual pressing, the adhesively bonded assembly is placed on a table lengthwise and is subjected, at the adhesive joint, to a detachment force exerted by the same operator. In order to detach the two test specimens, the operator holds one of the test specimens with one hand, and pulls the end of the other test specimen with the other hand, while exerting a detachment force perpendicular to the plane of adhesive bonding of the assembly.

(31) When the operator is able to detach the supports without force, it is estimated that the initial hold of the adhesive is weak (represented by minus, in results table 2).

(32) When the operator must provide force to detach the supports, it is estimated that the initial hold of the adhesive is strong (represented by minus, + in results table 2). When the force exerted by the operator is insufficient to detach the supports, it is estimated that the initial hold of the adhesive is excellent (represented by minus, ++ in results table 2).

(33) 5/ Evaluation of the Pot Stability

(34) The adhesive composition is kept at 23 C. and 50% relative humidity. The viscosity is measured every 7 days. If, at the end of 28 days, the increase in viscosity measured at 28 days represents less than 25% of the value of the viscosity measured 24 hours after preparation of the adhesive, then it is considered that the formulation is stable and does not change over time.

(35) The results are recorded in table 2 below.

(36) TABLE-US-00001 TABLE 1 Contents as % by dry weight relative to the total weight of the composition Examples Ingredients Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Ex 6 Ex 7 Ex 8 Ex 9 Ex 10 A1) Dispercoll C84 13.2 12.65 12.65 11.55 10.45 9.9 10.18 9.82 9.35 9.35 A2) Dispercoll C VP LS 2372/1 8.7 8.12 8.12 6.96 6.5 6.2 6.2 6.2 5.98 5.98 B) Secoia Exp 503 4 4 4 4 4 4 4 3.5 3.5 3.5 C) CaCO.sub.3 (>1 m) (D50 = 8 m) 16 20 Silica (>1 m) 20 28.7 21 21 21 20 19 19 Neuburg silica (>1 m) 10 15 10 10 14 14 Sepiolite (>1 m) 1.5 1.5 D) Unsaturated cyclic fatty alcohol having a cloud 0.38 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 point of 65 C. Unsaturated acyclic fatty alcohol, the HLB of 1.8 1.8 1.7 1.7 1.7 1.7 1.7 1.7 1.7 1.7 which is equal to 16.5 Mixture of sodium 0.25 0.25 0.25 0.25 0.3 0.3 0.3 0.3 0.3 0.3 monododecylphenoxybenzenedisulfonate salt and sodium didodecylphenoxybenzenedisulfonate salt E) ZnO 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 G) Acronal S813 9.15 8 8 6 7.42 5.87 6 6 5.87 Plextol R 5530 5.4 H) Granolit 150N 8 8 8 8 8 8 8 8 8 8 I) Non-ionic associative polyurethane thickener 0.45 0.45 0.5 0.5 0.3 0.3 0.3 0.3 0.3 0.3 J) PVC powder 6.42 6.7 6.7 6 4 4 4 4 4 4 K) Aqueous dispersion of silica nanoparticles 1.85 1.85 1.85 L) Additives (biocide, antioxidant, antifoaming 0.72 0.72 0.72 0.72 0.72 0.72 0.72 0.72 0.72 0.72 agent) F) Water q.s. q.s. q.s. q.s. q.s. q.s. q.s. q.s. q.s. q.s. 100 100 100 100 100 100 100 100 100 100 q.s.: sufficient amount to achieve a total composition weight of 100 g

(37) TABLE-US-00002 TABLE 2 Examples Characterization Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Ex 6 Ex 7 Ex 8 Ex 9 Ex 10 C1 C2 Drying time on laminate 45 40 35 30 25 20 15 20 22 22 40 45 (min) Shear strength 2 h 11 14 13 13 14 12 13 9 11 10 9 4 (kg/cm.sup.2) 24 h 25 29 27 27 25 29 25 24 26 24 12 16.4 7 d 30 33 31 32 36 34 35 30 35 33 18 16.6 Heat resistance ( C.) 125 125 115 120 120 120 140 140 135 130 115 110 Initial hold + + ++ + ++ ++ ++ ++ + + + + Pot stability yes yes yes yes yes yes yes yes yes yes yes yes