Water-based adhesive fixing composition having improved creep properties

Abstract

The present invention relates to a composition comprising at least one aqueous dispersion of a copolymer of the styrene-(meth)acrylic/(meth)acrylate type, at least one filler, and a particular thickening system, as well as the use of such a composition as a fixing glue.

Claims

1. An adhesive composition comprising: a) from 50 to 75 wt %, relative to the weight of the adhesive composition, of an aqueous dispersion in water of at least one polymer obtained from: (a1) a styrene monomer, and (a2) at least one comonomer that is a (meth)acrylic acid, a basic salt of said acid, an alkyl (meth)acrylate whose alkyl moiety, saturated or unsaturated, linear or branched, cyclic or acyclic, has 1 to 30 carbon atoms, said alkyl moiety optionally being interrupted by one or more oxygen atoms, optionally epoxidized and/or optionally terminated with a hydroxyl function, and optionally (a3) a silanized comonomer that is a vinyl silane or a silanized (meth)acrylic acid ester, the aqueous dispersion a) having a content of dry matter of 30 to 80 wt % relative to the weight of said dispersion a), b) from 2.5 to 6 wt %, relative to the weight of the adhesive composition, of at least one sepiolite, c) from 0.5 to 3 wt %, relative to the weight of the adhesive composition, of a composition comprising: c1) a water-based composition comprising at least one polymer obtained from: (c1.1) at least one monomer that is a (meth)acrylic acid, 2-acrylamido-2-methyl propane sulphonic acid, 2-sulphoethyl methacrylate, styrene phosphonic acid, or a basic salt of these acids, and (c1.2) at least one comonomer that is a (meth)acrylamide or vinyl pyrrolidone, the content of dry matter in the water-based composition c1) being 10 to 40 wt % relative to the weight of said water-based composition c1), and/or c2) a water-based composition comprising: (c2.1) at least one polymer obtained from: (c2.1.1) at least one monomer that is a (meth)acrylic acid ester or maleic acid ester, said ester comprising at least one hydrocarbon group, saturated or unsaturated, linear or branched, cyclic or acyclic, having from 8 to 30 carbon atoms, and which moreover may or may not be alkoxylated by one or more C.sub.1-C.sub.4 oxyalkylene groups, and (c2.1.2) at least one comonomer that is a (meth)acrylic acid or a (meth)acrylic acid ester not having a hydrocarbon group, saturated or unsaturated, linear or branched, cyclic or acyclic, having from 8 to 30 carbon atoms, or (c2.2) at least one polyurethane comprising at least one hydrocarbon group, saturated or unsaturated, linear or branched, cyclic or acyclic, having from 8 to 30 carbon atoms, and which moreover may or may not be alkoxylated by one or more C.sub.1-C.sub.4 oxyalkylene groups, the water-based composition c2) having content of dry matter 20 to 40 wt % relative to the weight of said water-based composition c2), and d) from 20 to 40 wt % of at least one filler.

2. The composition according to claim 1, wherein the polymer in the aqueous dispersion a) has a glass transition temperature (Tg) less than or equal to 65 C.

3. The composition according to claim 1, wherein the polymer in the water-based composition c1) is obtained from: (c1.1) at least one monomer that is a (meth)acrylic acid or basic salt thereof, and (c1.2) at least one comonomer that is a (meth)acrylamide.

4. The composition according to claim 1, wherein the water-based composition c1) is an inverted emulsion.

5. The composition according to claim 1, wherein the polymer (c2.1) comprised in the water-based composition c2) is obtained from: (c2.1.1) at least one monomer that is an alkyl (meth)acrylate or alkyl mono- or dimaleate, the alkyl moiety, linear or branched, cyclic or acyclic of each of these monomers having from 8 to 30 carbon atoms, and which moreover may or may not be alkoxylated by one or more C.sub.1-C.sub.4 oxyalkylene groups, and (c2.1.2) at least one comonomer from that is a (meth)acrylic acid or alkyl (meth)acrylate whose linear or branched, cyclic or acyclic alkyl moiety has 1 to 4 carbon atoms.

6. The composition according to claim 1, wherein the polymers (c2.1) and (c2.2) are associative polymers.

7. The composition according to claim 1, having a pH greater than or equal to 7.

8. The composition according to claim 1, wherein the filler is calcium carbonate, and said filler may be hydrophilic or hydrophobic, precipitated or micronized.

9. The composition according to claim 1, comprising at least one plasticizer that is a hydroxylated compound that is liquid at a temperature of 15 to 25 C., and possess from 4.0 to 5.0 milliequivalents of OH function per gram of plasticizer.

10. In a fixing glue, capable of fixing an element on a ceiling, a floor or an approximately vertical substrate, said fixing glue comprising an adhesive, wherein the improvement comprising using the adhesive of claim 1.

Description

BRIEF DESCRIPTION OF FIGURES

(1) FIG. 1 shows application of the adhesive of the invention to a substrate

(2) FIG. 2-4 shows the use of increasing weights on the substrate to test adhesion.

(3) The following examples are given purely for illustration of the invention and are not to be interpreted as limiting its scope.

(4) Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.

(5) In the foregoing and in the examples, all temperatures are set forth uncorrected in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.

(6) The entire disclosures of all applications, patents and publications, cited herein and of corresponding FR application No. 14/62.641, filed Dec. 17, 2014 are incorporated by reference herein.

EXAMPLES

(7) Each of the adhesive compositions in examples 1 to 3 is prepared by mixing the ingredients described in Table 1 below by the method of preparation described in application US2003/0144405. In particular, the composition in example 3 corresponds to the composition in the examples in patent application US2003/0144405. The filler used in this example is a highly dispersed hydrophilic silica sold by the company Wacker under the name Silica HDK T30, and the dispersant used in this example is a water-based composition of ammonium polyacrylate at 35 wt % dry extract, sold by the company BASF under the name Pigmentverteiler.

(8) The contents of the ingredients presented in Table 1 are expressed in grams.

(9) TABLE-US-00001 TABLE 1 Ex. 1 Ex. 2 Ex. 3 Ingredients (invention) (invention) (comparative) AxilatDS2120 61.4 61.6 64.75 Pangel S9 4.9 4.9 Silica HDK T30 2.0 Texipol 63-202 1.1 2.0 Acrysol TT615 1.4 CaCO.sub.3 30.5 30.6 29.9 Texanol 1.0 1.0 Ecodis P90 0.4 0.4 Pigmentverteiler 1.0 Water, additives q.s. 100 q.s. 100 q.s. 100 q.s.: quantity sufficient to reach a total weight of the composition of 100 g

(10) Two test series are carried out on each of the adhesive compositions prepared.

(11) Test Series No. 1:

(12) For each of the adhesive compositions prepared, the following are evaluated at the moment of use: the ease of use of the composition and the strength of the glued joint on wood, alternately varying the weight of the object glued on, until rupture of the glued joint occurs.

(13) The operating protocol followed for each of the adhesive compositions tested is described below.

(14) Operating Protocol:

(15) On the front of an oak board of about 155 g, with length of 25 cm and width of 10 cm, several weights are fixed so as to obtain an object (board+weight) of about 1.5 kg, representing gluing of approximately 60 kg/m.sup.2. The weights fixed are distributed uniformly on the surface of the board in order to obtain an object of uniform weight overall.

(16) After preparation of the adhesive composition, it is put in a mastic cartridge equipped with an extrusion nozzle having an outlet diameter of 5 mm and extruded manually using a skeleton gun on the back of the oak board.

(17) For each test, the adhesive composition is applied on the board in a zigzag pattern as illustrated in FIG. 1.

(18) The length of the strand of adhesive composition extruded is about 0.7 meters.

(19) Immediately after application of the adhesive composition, the coated face of the board is pressed firmly against a sheet of Placoplatre about 2.5 meters long and 1.20 meters wide, fixed beforehand on a vertical wall.

(20) The position of the board is recorded accurately on the Placoplatre sheet, for subsequently determining the creep properties of the adhesive composition.

(21) The assembly is left to dry for 24 hours at 20 C. and 60% relative humidity.

(22) Measurement of the Creep Properties Under Load (at 24 Hours):

(23) After drying for 24 h in the conditions stated above, the cohesion of the adhesive joint is evaluated.

(24) If the wooden board remained glued on its Placoplatre substrate without creep of more than 1 mm toward the floor, it is considered that the adhesive joint is strong enough to support the surface load applied of 60 kg/m.sup.2. Then the test is started again, increasing the surface load applied by 20 kg/m.sup.2 until the adhesive joint is no longer strong enough to support said load, i.e. until we observe: either detachment of the board, which drops to the floor, or creep of the adhesive joint. This creep is reflected in vertical movement of the board toward the floor of more than 1 mm relative to its initial position.

(25) FIGS. 2, 3 and 4 show the distribution of the weights fixed to the surface of the board corresponding to a surface load of 60 kg/m.sup.2, 80 kg/m.sup.2 and 100 kg/m.sup.2 respectively.

(26) The surface load applied before which detachment of the board is observed, corresponds to the maximum surface load allowing the object to be held in place. The value of the latter is expressed in kilograms per square meter and is given in Table 2.

(27) The results show that the compositions of examples 1 and 2 according to the invention are able to fix a heavier object on a wall than the composition of example 3 according to the prior art. The adhesive compositions according to the invention therefore have better tack than the composition of the prior art.

(28) Evaluation of the Ease of Use of the Adhesive Composition:

(29) The extrudability of the adhesive composition is evaluated at the moment of application of the composition by the operator in the conditions described above.

(30) It was found that the compositions of examples 1 and 2 according to the invention offer the same advantages in terms of ease of use, notably by extrusion, relative to the composition of example 3 according to the prior art.

(31) Test Series No. 2: Tensile Shear Strength

(32) Unless stated otherwise in the present application, preparation of the test specimens and the tests of tensile shear strength were carried out according to standard NF EN 1465, using a Zwick Z020 dynamometer.

(33) The test specimens used for the tests are prepared by cutting strips 10 cm long, 2.5 cm wide and 5 mm thick from natural beech.

(34) A test specimen of beech, with its free end coated beforehand with an adhesive composition on an overlap 2.5 cm long and 2.5 cm wide, is put in each of the jaws of the dynamometer. The test specimens are assembled by aligning and bringing into contact the zones coated with adhesive, pressing them against one another.

(35) Coating with the adhesive composition was carried out using a standardized notched-edge spatula so as to obtain, after pressing, a continuous adhesive joint with thickness of about 0.2 mm on the overlapped zone.

(36) The assembly is left to dry for 7 days at 23 C. and 50% relative humidity.

(37) Tensile Shear Strength (at 7 Days):

(38) After drying for 7 days in the conditions mentioned above, the strength of the adhesive joint is evaluated by applying a vertical pulling force at a constant speed of 500 meters per second.

(39) The shearing force applied on the adhesive joint is measured continuously until rupture of the assembly. The maximum value recorded before rupture corresponds to the shear strength of the adhesive composition at 7 days. The results are expressed in newtons per square meter and are given in Table 2 below.

(40) The values of shear strength observed for the compositions of examples 1 and 2 according to the invention are above 20.10.sup.5 N/m.sup.2 (minimum value acceptable), and even above 50.10.sup.5 N/m.sup.2, thus showing that the adhesive joint formed gives good hold (called final tack) even 7 days after bringing the surfaces coated with adhesive into contact. This value at 7 days demonstrates the maximum value of gluing attained, while knowing that this value is maintained over time for several years.

(41) TABLE-US-00002 TABLE 2 Ex. 1 Ex. 2 Ex. 3 Characteristics (invention) (invention) (comparative) Maximum load tolerated at 100 100 60 24 h (in kg/m.sup.2) (oak/Placoplatre) Tensile shear strength at 7 58 .Math. 10.sup.5 67 .Math. 10.sup.5 days (in N/m.sup.2) (beech/beech)

(42) The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.

(43) From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.