Phthalate-free plasticized adhesive sealant composition

Abstract

Adhesive sealant composition comprising at least one moisture-crosslinkable prepolymer and, as plasticizing agent, an ester compound of formula (I): ##STR00001##
in which: R.sup.1, R.sup.2 and R.sup.3 represent an oxycarbonylalkyl radical of 4 to 20 carbon atoms; R.sup.4 represents a hydrogen atom, a methyl or ethyl radical or else a radical: —CH.sub.2—R.sup.5 in which R.sup.5 represents an oxycarbonylalkyl radical of 4 to 20 carbon atoms.

Claims

1. An adhesive sealant composition comprising: 10% to 30% by weight of at least one moisture-crosslinkable prepolymer which is a polyurethane comprising —NCO end groups, 5% to 35% by weight of, as a plasticizing agent, an ester compound of formula (I): ##STR00012## in which: R.sup.1, R.sup.2 and R.sup.3, which are identical and each represent an oxycarbonylalkyl radical of formula —O—C(O)-alkyl having from 4 or 5 carbon atoms; R.sup.4 represents a radical: —CH.sub.2—R.sup.5 in which R.sup.5 is identical to R.sup.1, R.sup.2 and R.sup.3, from 20% to 70% by weight of at least one filler, and from 0.01% to 1% by weight of at least one crosslinking catalyst, the percentages by weight being expressed with respect to the total weight of the adhesive sealant composition.

2. The adhesive sealant composition according to claim 1, wherein the ester compound of formula (I) is pentaerythritol tetravalerate.

3. The adhesive sealant composition according to claim 1, having from 15% to 30% by weight, on the basis of the weight of the said composition, of the ester of formula (I).

4. The adhesive sealant composition according to claim 1, that is a single-component sealant composition.

5. The adhesive sealant composition according to claim 1, comprising: from 15% to 25% by weight of the moisture-crosslinkable prepolymer, from 15% to 30% by weight of the ester of formula (I), and from 40% to 70% by weight of the filler, the percentages by weight being expressed with respect to the total weight of the adhesive sealant composition.

6. Ready-for-use article, comprising the adhesive sealant composition as defined in claim 1 in a hermetic packaging sheltered from air.

7. Article according to claim 6, wherein the packaging is an aluminium cartridge provided with a protective cap.

Description

EXAMPLE A REFERENCE

(1) thixotropic composition having an anti-sag effect consisting of a 23.3% weight/weight suspension of bis-urea in DIDP

(2) First of all, a solution A of 17.17% weight/weight of n-butylamine in 82.83% weight/weight of DIDP and a solution B of 29.46% weight/weight of 4,4′-MDI in 70.34% weight/weight of DIDP are prepared. The two solutions A and B are heated to 100° C. and then introduced, each under a pressure of 100 bar, into a reactor, in which they are sprayed continuously over one another in a ratio A/B=50.1/49.9 by weight, corresponding to an n-butylamine/MDI molar ratio equal to 2. The reaction is immediate and the temperature of the reactor reaches 140° C. at the end of manufacture.

(3) At the reactor outlet, a stable 23.3% weight/weight dispersion of a bis-urea in DIDP is obtained, the bis-urea being of formula:

(4) ##STR00011##

(5) The Brookfield viscosity of the suspension, measured at 23° C., is 15 Pa.Math.s.

Example B Reference

(6) adhesive sealant composition based on polyurethane prepolymer comprising-NCO end groups comprising, as plasticizer, DIDP and, as anti-sag agent, the thixotropic composition of Example A

(7) The following sealant composition, in which the percentages are percentages weight/weight, is prepared by simple mixing of the ingredients: 17% of polyurethane comprising —NCO end groups obtained by reaction of a mixture of 80% by weight of tolylene 2,4-diisocyanate and 20% by weight of tolylene 2,6-diisocyanate with a mixture of a polyether diol with a molar mass of 2000 g/mol and of a polyether triol with a molar mass of 4200 g/mol, 25% of carbonate filler, 20% by weight of PVC, 15% by weight of the thixotropic composition of Example A, 10% by weight of DIDP as plasticizer, 8% by weight of xylene, 5% by weight of other additives, including the crosslinking catalyst.

(8) The polyurethane was introduced into the composition in the form of a solution in xylene.

(9) The sealant composition obtained is packaged in an aluminium cartridge, provided with a nozzle, for the purpose of its application by means of a gun for the tests described below.

B.1. Test on the Migration of the Plasticizer

(10) This test is a good indicator of the migration of the plasticizer out of the crosslinked sealant.

(11) A weight of 1 g of sealant, in the approximate shape of a sphere, is deposited, by means of the cartridge containing the composition of Example B, at the centre of a 1.sup.st square glass sheet with a side length of 5 cm, which was placed horizontally beforehand.

(12) A 2.sup.nd glass sheet identical to the 1.sup.st is subsequently strongly applied to the said sealant mass and by means of a manual pressure, so as to superimpose the two sheets and to thus spread the sealant in the approximate shape of a disc with a diameter of approximately 4.5 cm.

(13) There is then observed, through the upper glass sheet, the appearance of a transparent liquid exuded by the compressed disc of sealant, in the form of a ring surrounding the said disc, with an annular radius of between 1 and 2 mm.

B.2. Test on the Flow of the Non-Crosslinked Sealant after Extrusion

(14) The aim of this test is to assess the extrudability, through the nozzle, of the cartridge-packaged sealant, under the effect of the pressure exerted by the piston, which is integral with the trigger of the gun actuated by the operator.

(15) With this aim, the sealant is extruded under air pressure through a calibrated nozzle and the weight discharged over one minute is measured.

(16) The sealant to be tested is placed in a cylinder-shaped cup (diameter of 24 mm) terminated by an extrusion nozzle with a diameter of 4 mm and a length of 22.5 mm, and a pressure of 3 bars is exerted on the sealant by means of a suitable appliance, the operation being carried out in a climate-controlled chamber at ambient temperature (23° C.).

(17) The flow rate measured is shown in g/minute in the Table below and corresponds to a perfectly compliant sealant behaviour.

B.3. Test on the Tensile Strength Properties of an Adhesive Joint Formed by the Crosslinked Sealant and Uniting Two Substrates

(18) This test is carried out for an adhesive joint uniting two concrete substrates and also for an adhesive joint uniting two aluminium substrates.

(19) The two concrete substrates intended to be joined together are two identical substrates of parallelepipedal shape, having a length of 75 mm, a width of 12 mm and a height of 6 mm, the rectangular face of each substrate intended to be in contact with the joint having a length of 75 mm and a height of 12 mm.

(20) The two aluminium substrates intended to be joined together are two identical substrates of parallelepipedal shape, having a length of 75 mm, a width of 25 mm and a height of 12 mm, the two rectangular faces intended to be in contact with the joint having a length of 75 mm and a height of 12 mm.

B.3.1. Preparation of the Joint Specimens to be Tested

(21) The concrete (or aluminium) joints to be tested are prepared using the sealant of Example B, so that the crosslinked sealant joint which bonds the two substrates is centred on the corresponding rectangular faces, and has a parallelepipedal shape with a length of 50 mm, a width of 12 mm and a height of 12 mm.

(22) The details relating to the shape of the adhesive joint specimens and their preparation are given in European Standard EN 8339 (cf. § 6 and 7). In particular, the sealant of Example 2 is crosslinked by a residence of 28 days in an oven at 23° C. and 50% relative humidity (according to Method A shown in the standard), followed by an alternating cycle of residences in an oven at 70° C. and residences in water at 23° C. (according to Method B shown in the standard).

B.3.2. Tensile Tests on the Joints

(23) The joint specimens prepared according to B.3.1, are drawn in a tensile testing device, the movable jaw of which moves at a constant rate equal to 5.5 mm/minute. The stress applied and the elongation of the test specimen (expressed as %) during the drawing thereof are recorded.

(24) The 100% modulus, corresponding to the stress (in MPa) recorded for an elongation of the joint of 100%, and also the elongation (as %) measured at the breaking of the joint are shown in the table below, for each type of substrate: concrete or aluminium.

B.4. Creep Test

(25) The degree of creep (or sagging or slump) of a sealant employed in a vertical joint is measured according to Standard ASTM D 2202.

(26) An absence of creep of the sealant, i.e. a distance measured on the graduated scale of the appliance of less than 2.5 mm, is observed.

Example C Reference

(27) thixotropic composition consisting of a 23.3% weight/weight suspension of bis-urea in pentaerythritol tetravalerate

(28) Example A is repeated, the DIDP being replaced with pentaerythritol tetravalerate.

(29) A stable 23.3% weight/weight dispersion of the same bis-urea is obtained, the Brookfield viscosity of which, measured at 23° C., is 16.7 Pa.Math.s.

Example 1

According to the Invention

(30) adhesive sealant composition based on polyurethane prepolymer comprising-NCO end groups comprising, as plasticizer, pentaerythritol tetravalerate and, as anti-sag agent, the thixotropic composition of Example C

(31) Example B is repeated, replacing, during the preparation of the sealant: the 10% of DIDP with 10% of pentaerythritol tetravalerate, and the thixotropic composition of Example A with that of Example C.

(32) The results of the tests are shown in the table below.

(33) TABLE-US-00001 Example B Example 1 Migration of the plasticizer between 1 and 2 <0.5 Annular radius (in mm) Flow after extrusion 69 69 (in g/minute) 100% modulus (in MPa) 0.44 0.48 concrete substrate Elongation at break 480 563 (as %) concrete substrate 100% modulus (in MPa) 0.41 0.46 aluminium substrate Elongation at break 213 387 (as %) aluminium substrate Creep distance (in mm) <2.5 <2.5 according to ASTM D 2202

(34) These results reveal, for the sealant of Example 1, a behaviour in the extrusion during the cartridge application which is identical to that of Example B.

(35) The 100% modulus (which indicates the cohesion of the adhesive joint) and the elongation at break (which corresponds to the elasticity of the adhesive joint) are each improved for Example 1 according to the invention in comparison with the reference Example B, both for substrates made of concrete and for substrates made of aluminium.