ADHESIVE COMPOSITION

Abstract

The present invention is in the field of an improved adhesive composition, use of said composition and products comprising said composition. The adhesive composition may be a one component and a two component adhesive, each component typically comprising various ingredients. The present adhesives are water-based dispersions.

Claims

1. Aqueous adhesive composition comprising (a1) 40-97 wt. % of a dispersion, comprising one or more of polychloroprene dispersion, polyurethane dispersion, natural rubber dispersion, styrene-butadiene-styrene copolymer dispersion, nitrile-butadiene rubber, polyvinyl butyral dispersion, styrene-butadiene rubber dispersion, and combinations thereof, the dispersion comprising 30-80 wt. % solids, (a2) 2-50 wt. % plasticizer, wherein the plasticizer is selected from mono-esters from benzoic acid and a C.sub.4-C.sub.16 alcohol, and combinations thereof, (a3) 0.0-5 wt. % surfactant, (a8) 0.1-40 wt. % pH stabilizer, (a9) 0.1-2 wt. % of one or more of a fungicide, a bactericide, and an algaecide, and preferably at least one of (a5) 0.1-40 wt. % of a resin dispersion, the resin dispersion comprising 30-70 wt. % solids, (a6) 0.1-8 wt. % of an acid binder, (a7) 0.1-15 wt. % thickener, (a10) 0.001-1 wt. % defoamer, (a11) 0.001-1 wt. % emulsifier, (a12) 0.001-1 wt. % wetting agent (a13) 0.1-2 wt. % of a colorant, and (a14) 0.1-3 wt. % of anti-degradant, (a4) the remainder being water, wherein all parts are calculated based on the total weight of the composition.

2. Adhesive composition according to claim 1, further wherein the alcohol is selected from single branch alcohols, branched alcohols, primary alcohols, secondary alcohols, tertiary alcohols, substituted alcohols, and combinations thereof.

3. Adhesive composition according to claim 1, wherein the alcohol is a C.sub.9-C.sub.11 alcohol, preferably a C.sub.10 alcohol.

4. Adhesive composition according to claim 1, wherein the dispersion (a1) comprises 16-97 wt. % polychloroprene dispersion, preferably 40-76 wt. %, more preferably 50-72 wt. %, even more preferably 55-70 wt. %, such as 60-65 wt. %.

5. Adhesive composition according to claim 1, wherein a (dynamic) viscosity is 20-25000 mPa*s (according to ISO 2555).

6. Adhesive composition according to claim 1, wherein a pH is 7-13.5.

7. Adhesive composition according to claim 1, wherein a glass transition temperature is 193-223K (80 to 50 C.) (according to ISO 22768).

8. Adhesive composition according to claim 1, wherein (a6) the acid binder is one or more of a basic metal salt, preferably an oxide salt, a bicarbonate salt, or a carbonate salt.

9. Adhesive composition according to claim 1, wherein (a7) the thickener is one or more of a gum.

10. Use of an adhesive composition according to claim 1, for one or more of obtaining a low glass transition temperature, for high energy impact application, for prolonged storage, for improved stability, and for low temperature use.

11. Product comprising an adhesive composition according to claim 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention relates in a first aspect to a composition according to claim 1.

[0026] In an example of the present composition the alcohol is selected from single branch alcohols, branched alcohols, primary alcohols, secondary alcohols, tertiary alcohols, substituted alcohols, alcohols comprising one or more double bonds, alcohols comprising one or more triple bonds, and combinations thereof, such as butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, and hexadecanol. It has been found that not too long chained alcohols, and not too short alcohols, the length of the alcohol relating to a longest chain thereof, are preferred in terms of applicability to the present composition, mixing properties, lowering Tg, stabilizing the pH, etc. In particular it is preferred to use a C9-C11 alcohol, preferably a C10 alcohol. It is noted that the present esters often relate to a mixture of esters, e.g. a C9-C11 benzoate mixture, having mainly C10-benzoate, and some C9- and C11 benzoate.

[0027] The present composition may have various optional components, such as (a5) 0.1-40 wt. % of a resin dispersion, preferably 0.2-30 wt. %, more preferably 0.3-20 wt. %, the resin dispersion comprising 30-70 wt. % solids, preferably having 40-60 wt. % solids, more preferably having 45-55 wt. % solids, (a6) 0.1-8 wt. % of an acid binder, preferably 0.2-5 wt. %, more preferably 0.3-3 wt. %, (a7) 0.1-15 wt. % thickener, preferably 0.2-10 wt. %, more preferably 0.5-5 wt. %, (a10) 0.001-1 wt. % defoamer, preferably 0.005-0.5 wt. %, more preferably 0.01-0.05 wt. %, (a11) 0.001-1 wt. % emulsifier, preferably 0.005-0.5 wt. %, more preferably 0.01-0.05 wt. %, (a12) 0.001-1 wt. % wetting agent preferably 0.01-0.3 wt. %, more preferably 0.05-0.1 wt. %, (a13) 0.1-2 wt. % of a colorant, preferably 0.2-1 wt. %, more preferably 0.3-0.5 wt. %, and (a14) 0.1-3 wt. % of anti-degradant, preferably 0.2-1 wt. %, more preferably 0.3-0.5 wt. %.

[0028] In an example of the present composition the dispersion (a1) comprises 16-97 wt. % polychloroprene dispersion, preferably 20-80 wt. %, preferably 40-76 wt. %, more preferably 50-72 wt. %, even more preferably 55-70 wt. %, such as 60-65 wt. %.

[0029] In an example of the present composition a (dynamic) viscosity is 20-25000 mPa*s (according to ISO 2555), such as 0.1-5 Pa*s. Such a viscosity is preferred in view of the manner of application, such as by a spray gun.

[0030] In an example of the present composition a pH is 7-13.5, such as 10-11.5. This pH is found to keep the composition stable for a prolonged period of times, typically a few months, and prevents the plasticizer from segregating.

[0031] In an example of the present composition a glass transition temperature is 193-223K (80 to 50 C.) (according to ISO 22768). For sake of comparison prior art adhesives with 17.8 wt. % DIBP or DBT have a glass transition temperature of 218.3 K and 212.0 K, respectively, versus the present 17.8 wt. % C.sub.10-benzoate mono ester of 208.5K. The present adhesive is therefor also particularly suited when used at a low temperature.

[0032] In an example of the present composition (a6) the acid binder is one or more of a basic metal salt, preferably an oxide salt, a bicarbonate salt, or a carbonate salt.

[0033] In an example of the present composition (a7) the thickener is one or more of a gum.

[0034] In a second aspect the present invention relates to a use of the present adhesive composition for one or more of obtaining a low glass transition temperature, for high energy impact application, for prolonged storage, for improved stability, and for low temperature use.

[0035] In a third aspect the present invention relates to a product comprising the present adhesive composition.

[0036] The invention is further detailed by the accompanying figures and examples, which are exemplary and explanatory of nature and are not limiting the scope of the invention. To the person skilled in the art it may be clear that many variants, being obvious or not, may be conceivable falling within the scope of protection, defined by the present claims.

EXAMPLES/EXPERIMENTS

[0037] The invention although described in detailed explanatory context may be best understood in conjunction with the accompanying examples.

TABLE-US-00001 TABLE 1 Adhesive compositions according to the invention (1-3), prior art compositions 4 (DIBP) and 5 (DBT), and comparative example 6 without plasticizer. Adhesive compositions Sample no. 1 2 3 4 5 6 Dispercoll 600.0 600.0 600.0 600.0 600.0 600.0 Benzoate 80.0 160.0 240.0 DIBP 160.0 DBT 160.0 Additives + 140.25 140.25 140.25 140.25 140.25 140.25 water Totaal 820.25 900.25 980.25 900.25 900.25 740.25

TABLE-US-00002 TABLE 2 Results of various T.sub.g measurements using method EN ISO 16805 on the adhesive compositions of table 1. Determination of the Glass Transition Point (Tg) Equipment: Kalorimeter DSC-7 (Fa. Perkin-Elmer) Heizrate 20 K/min, Khlrate 320 K/min Sample no. 1 2 3 4 5 6 Values in C. 1st measurement 59.8 70.0 74.9 58.5 66.5 39.1 2nd measurement 55.8 64.5 70.8 54.7 61.0 42.5 Values in K 1st measurement 213.4 203.2 198.3 214.7 206.7 234.1 2nd measurement 217.4 208.7 202.4 218.5 212.2 230.7
1.sup.st measurement is first heating cycle, 2.sup.nd measurement is second measurement. The 3.sup.rd is not given as the values do not significantly differ from the 2.sup.nd measurement.

[0038] From table 2 it can be seen that the present compositions 1-3 perform better in terms of glass transition temperature T.sub.g, compared to prior art adhesive compositions 4 and 5. It is noted that a slight difference between the results of first and second measurement for the glass transition temperature is present; such is considered typical as the result varies from first to second measurement and thereafter (third and subsequent measurement) remains constant. In this sense the second measurement may be considered as more indicative for the adhesives. At an equal amount of plasticizer sample 2 has a lower T.sub.g compared to samples 4 and 5, which indicates that sample 2 will stay (more) elastic at a lower temperature compared to 4 and 5. A lower T.sub.g may be considered, amongst others, as an indication of a better contactibility of the adhesive composition and a longer open time.

[0039] The tensile strength is measured according to ISO 37/DIN 53504.

TABLE-US-00003 TABLE 3 Results of the tensile tests according to ISO 37/DIN 53504 on the adhesive compositions of table 1. Tensile Strength measurement according ISO37/DIN53504 Equipment: Zwick Z010 Elongation speed is 2000 mm/min. Dumbell-shaped sample S2. Sample no. Elongation 1 2 3 4 5 6 Tensile Strength at a given elongation in N/mm.sup.2 or MPa, measured at Room Temperature. 50% 1.94 1.78 1.29 1.45 1.70 3.27 100% 2.04 1.89 1.40 1.56 1.84 3.26 200% 2.56 2.53 1.75 1.92 2.37 3.60 Tensile Strength at a given elongation in N/mm.sup.2 or MPa, measured at 25 C. 50% 3.26 2.97 2.20 3.21 3.54 6.44 100% 3.77 3.64 2.71 3.83 4.32 200% 4.90 5.25 3.85 5.40 6.11

[0040] From table 3 it can be seen that sample 2 has a lower tensile strength at lower temperatures such as 25 C. A lower tensile stress shows that Sample 2 is more flexible at this temperature compared to samples 4 and 5 (prior art). Also, this lower tensile strength in sample 2 compared to samples 4 and 5 is not present at room temperature. This shows the tensile strength of sample 2 does not increase as much as samples 4 and 5. This shows again that sample 2 is the better choice for low temperatures.

TABLE-US-00004 TABLE 4 Results of pH measurements during storage on the adhesive compositions of table 1 pH measurements Equipement: Mettler Toledo MP220; Electrode: InLab Pro Rotine pH Measured at Room Temperature Sample no. 1 2 3 4 5 6 1 day 12.56 12.55 12.49 12.49 12.42 12.57 84 days 12.34 12.32 12.18 11.07 10.22 12.34 254 days 11.83 11.61 11.18 9.98 9.49 11.62 pH pH, 84 days 0.22 0.23 0.31 1.42 2.20 0.23 pH, 254 days 0.73 0.94 1.31 2.51 2.93 0.95

[0041] From table 4 it can be seen that the pH of sample 2 when stored does decrease much less compared to the samples 4 and 5. The decrease of the pH is a measurement of storage stability so this shows that the plasticizer of the present invention is much more storage stable in this alkaline environment than the plasticizers of the prior art.

[0042] It should be appreciated that for commercial application it may be preferable to use one or more variations of the present system, which would similar be to the ones disclosed in the present application and are within the spirit of the invention.