Organic carbonate as blowing agent

Abstract

A thermally expandable composition that comprises at least one organic compound having at least one cyclic carbonate group as a blowing agent, at least one catalyst for the blowing agent, at least one reactive binder and at least one hardener and/or accelerator. Also provided are molded bodies containing the composition, and a method for sealing and filling hollow spaces in components, in order to strengthen or stiffen components, in particular hollow components, and for adhering movable components through use of molded bodies of this type, as well as to the use of corresponding cyclic organic carbonates as a blowing agent in thermally expandable compositions.

Claims

1. A thermally expandable composition containing: 1 (1) at least one organic compound comprising at least one cyclic carbonate group as a chemical blowing agent, (2) at least one catalyst for the blowing agent, (3) at least one reactive binder, and (4) at least one hardener and/or accelerator.

2. The thermally expandable composition according to claim 1, wherein the at least one organic compound comprising at least one cyclic carbonate group as a chemical blowing agent comprises a polyether and/or polyester, and wherein at least two, cyclic carbonate groups are bound to the polyether and/or polyester.

3. The thermally expandable composition according to claim 1, wherein the at least one organic compound used as a chemical blowing agent is a cyclic organic carbonate of Formula (I) ##STR00006## wherein is a single bond or a double bond, where if the ring contains a double bond, R.sub.1 is not bound by an exocyclic double bond, but rather by a single bond; and R.sub.1 is a linear or branched, substituted or unsubstituted alkyl, a linear or branched, substituted or unsubstituted heteroalkyl, a linear or branched, substituted or unsubstituted alkenyl, a linear or branched, substituted or unsubstituted alkynyl, a substituted or unsubstituted cycloalkyl, a substituted or unsubstituted aryl, or —C(O)—R.sup.a, where R.sup.a is a linear or branched, substituted or unsubstituted alkyl, a linear or branched, substituted or unsubstituted heteroalkyl, a linear or branched, substituted or unsubstituted alkenyl, a linear or branched, substituted or unsubstituted alkynyl, a substituted or unsubstituted cycloalkyl, or a substituted or unsubstituted aryl; a is an integer from 0 to 5; and r is a natural number from 1 to 10.

4. The thermally expandable composition according to claim 3, wherein the at least one organic compound used as a blowing agent is a cyclic organic carbonate of Formula (II) ##STR00007## wherein , a and r are as defined above and R.sub.2 is defined in the same way as R.sub.1.

5. The thermally expandable composition according to claim 1, wherein the at least one organic compound used as a blowing agent is a cyclic organic carbonate of Formula (III) or (IV) ##STR00008## wherein each b and each c are, independently of one another, a natural number from 1 to 5; and each X is selected independently from the group consisting of O, S and N.

6. The thermally expandable composition according to claim 1, wherein the at least one organic compound used as a blowing agent is a cyclic organic carbonate of Formula (V) or (VI) ##STR00009##

7. The thermally expandable composition according to claim 1, wherein the reactive binder is selected from the group consisting of epoxides, rubbers, peroxidically crosslinkable polymers and combinations thereof.

8. The thermally expandable composition according to claim 1, wherein the at least one catalyst is selected from the group consisting of Lewis acids, Brønsted acids and mixtures thereof.

9. The thermally expandable composition according to claim 8, wherein the at least one catalyst is selected from the group consisting of mineral acids and salts thereof, carboxylic acids and salts thereof, metal complexes, metal salts and mixtures thereof.

10. The thermally expandable composition according to claim 1, wherein the thermally expandable composition comprises from 0.1 to 40 wt. % of the at least one organic carbonate, based on total weight of the thermally expandable composition.

11. A shaped body comprising the thermally expandable composition according to claim 1.

12. A method for sealing and filling cavities in components, for strengthening or stiffening components, optionally hollow components, and for bonding movable components, comprising: applying the thermally expandable composition according to claim 1 to a component, optionally in a cavity of the component, or between movable components; and heating to expand and cure said composition such that the thermally expandable composition seals, fills, strengthens or stiffens the component or bonds the movable components.

13. The method according to claim 12 for sealing and filling cavities in components and for strengthening or stiffening components, wherein a shaped body comprising the thermally expandable composition is inserted into a component, and is then heated to a temperature of above 30° C., such that the thermally expandable composition expands, and seals, fills, strengthens or stiffens the component.

14. A method for acoustically sealing cavities in components and/or for sealing cavities in components from water and/or moisture, or for strengthening or stiffening hollow components, comprising inserting the shaped body according to claim 11 into a cavity in the components or into the hollow components; and expanding and curing by heating the thermally expandable composition of the shaped body.

15. The method according to claim 12, comprising foaming the thermally expandable composition by heating in the presence of the at least one organic compound comprising at least one cyclic carbonate group as a chemical blowing agent in the thermally expandable composition wherein the thermally expandable composition comprises from 0.1 to 40 wt. % of the at least one organic carbonate, based on total weight of the thermally expandable composition.

Description

PRACTICAL EXAMPLES

Example 1: Synthesis of Organic Carbonates from Epoxides and Carbon Dioxide

(1) Tetrabutylammonium bromide, chloride and iodide were obtained from Acros. The epoxides D.E.R. 331 and D.E.R. 749 were obtained from Dow Chemicals. Celloxide 2021P was obtained from Daicel, and Prepo 2000LV was obtained from Henkel AG & Co. KGaA.

(2) The carbonates were prepared using a two-part 1-liter glass reactor equipped with a hollow mechanical stirrer and a thermometer. The temperature was kept constant by connecting the thermometer to a hot plate. Dry ice (CO.sub.2) was supplied to another 1-liter balloon. The released gas was introduced into the main reactor through a polyethylene tube by means of the hollow stirrer. The epoxide was supplied to the reactor, together with the corresponding catalyst (10 wt. % of the epoxide), and heated at 140° C. while being continuously stirred. Bubbles could be observed in the epoxide mixture.

(3) Dry ice was added to the 1-liter balloon every 4 to 5 hours. After 2 to 3 days, the mixture was white and highly viscous. At this stage, the reaction mixture was cooled.

(4) TABLE-US-00001 TABLE 1 Synthesis of carbonates using tetrabutylammonium halogen salts as catalysts Yield after 1 Yield after 2 Yield after 3 day* days* days* Tetrabutylammonium 77.8% ~99% 100% bromide Tetrabutylammonium 94.0%   94% 94% chloride Tetrabutylammonium 69.2% 90.9% 100% iodide Epoxide: D.E.R. 331: 2,2-bis-[4-(2,3-epoxypropoxy)phenyl]propane/no solvent/*yield calculated from .sup.1H NMR measurement.

(5) TABLE-US-00002 TABLE 2 Epoxide resins used as starting materials for the synthesis of organic carbonates Epoxide Molecule structure Form EEW* EGC** D.E.R. 331 product of liquid 182-192 5,200-5,500 epichlorohydrin with bisphenol A Prepo 2000LV prepolymer liquid D.E.R. 749 product of liquid epichlorohydrin and tetramethylolmethane (pentaerythritol) Celloxide double heterocycle liquid 128-145 2021P *EEW: epoxide equivalent weight (g/eq); **EGC: epoxide group content (mmol/kg)

(6) The synthesis of an organic carbonate of Formula (VII) starting from D.E.R. 749 and using tetrabutylammonium chloride as the synthesis catalyst and the decomposition mechanism using Cu(acac).sub.2 as the decomposition catalyst are shown in the following diagram.

(7) ##STR00005##

Example 2: Epoxide-Based, Thermo-Hardening Adhesives Containing the Blowing Accent According to the Invention

(8) First Recipe

(9) Kane Ace MX-125 (bisphenol-A-diglycidyl ether+25% core shell particle (styrene-butadiene copolymer)) was obtained from Kaneka, and Cab-o-Sil TS 720 and Monarch 580 were obtained from Cabot. Super 40 was obtained from Ulmer Weisskalk. 3M glass bubble VS5500 was obtained from 3M. Kevlar 1F1464 was obtained from DuPont. Omyacarb 4HD was obtained from Omya. Dyhard UR700 (3-phenyl-1,1-dimethylurea) and Dyhard 100SH (dicyandiamide) were obtained from Alz chem.

(10) TABLE-US-00003 TABLE 3 First recipe Compound wt. % 1 D.E.R. 331 11.78%* 1 Kane Ace MX-125 23.56%* 1 Prepo 2000LV 15.26%* 2 Cab-o-Sil TS 720 1.88%* 3 Super 40 3.77%* 3 3M glass bubble VS5500 13.95%* 4 Kevlar 1F1464 1.88%* 4 Omyacarb 4HD 16.58%* 5 Monarch 580 0.19%* 5 Dyhard UR700 0.19%* 5 Dyhard 100SH 3.96%* 6 carbonate 7.00%* 6 catalyst ** *% of the total weight/ ** this parameter is variable

(11) The formulation was obtained by step-by-step mixing of the components, as specified by the numbering in table 3. D.E.R. 331, Kane Ace MX-125 and Prepo 2000LV were filled into a container, which was adapted to the desired amounts. Mixing was carried out using a mechanical stirrer (MOLTENI/LABMAX P2 3/1—2001 type coupled to a DIAPHRAGM VACUUM PUMP/MD 4C 3.0 m.sup.3/h). The mixture was mixed in vacuo for 15 minutes. Cab-o-Sil TS 720 was added and slowly mixed at atmospheric pressure, and this was followed by further mixing in vacuo. After 15 minutes, Super 40 and 3M glass bubble VS5500 were added using the same procedure as for Cab-o-Sil TS 700. For steps 4, 5 and 6, the compounds were added to the mixture and mixed therein in vacuo for 15 minutes in each case.

(12) The weight proportion of the catalyst was varied depending on the carbonate (molecular weight) and the expected reaction speed. The obtained mixture was a black, fibrous formulation.

(13) Second Recipe

(14) The recipe was prepared in a step-by-step fashion according to table 4. A polypropylene container was loaded with the first compounds. The mixture was mixed for 1 minute at 0.2 kpa and 2000 r/min using a mixer of the THINKY PLANETARY vacuum mixer Aro 310 type. For the subsequent steps, the same procedure was selected. The obtained mixture is a red, paste-like formulation. Graphtol Rot LG was obtained from Clariant.

(15) TABLE-US-00004 TABLE 4 Second test recipe having a lower viscosity and not having fiber fillers Compound wt. % 1 D.E.R. 331 16.56%* 1 Kane Ace MX-125 33.20%* 1 Prepo 2000LV 21.52%* 2 Cab-o-Sil TS 720 2.64%* 5 Graphtol ROT LG 0.24%* 5 Dyhard UR700 0.24%* 5 Dyhard 100SH 5.60%* 6 carbonate 20.00%* 6 catalyst ** *% of the total weight/ ** this parameter is variable

(16) In order to analyze the organic carbonates obtained in example 1, samples of the above-mentioned recipes that contained the corresponding carbonates (see table 5) were thermo-hardened and the expansion was determined from the change in density. In addition, the conversion rate was tested as a function of the loss in mass resulting from the decomposition of the carbonate. The density of the completely hardened reference formulation without any blowing agents was determined as being 1.06 g/cm.sup.3.

(17) TABLE-US-00005 TABLE 5 Formulations comprising carbonates Carbonate synthesized by Loss in mass Density after hardening D.E.R. 331 carbonate 4.4% 0.72 Prepo 2000LV carbonate 5.0% 0.95 D.E.R. 749 carbonate 1.9% 0.67 Celloxide 2021P carbonate 4.0% 0.84 Conditions: 5 mol. % Cu(acac).sub.2/hardening at 180° C. for 20 minutes

(18) The formulations that have the lowest density after hardening are those that have the best expansion rates. Carbonates prepared from D.E.R. 331 and D.E.R. 749 were the carbonates that resulted in the best expansion for the first recipe. It is also clear from the results that expansion alone is not a good indicator of an effective blowing agent, since some of the formed CO.sub.2 can be lost owing to viscosities that are too low. This indicates the importance of fine tuning the blowing agent in relation to the expected hardening window, and this can be achieved for the organic carbonates simply by selecting different catalysts or different catalyst amounts.

Example 3: Organic Carbonates as Blowing Agents for Crosslinkable Polyethylene Vinyl Acetate (EVA)

(19) Recipe Comprising EVA

(20) The two polymers Alcudia EVA PA 538 and Elvaloy 4170 were obtained from Repsol and DuPont, respectively. The peroxide Peroxan HX 45P was obtained from Pergan.

(21) TABLE-US-00006 TABLE 6 EVA formulation Compound wt. % 1 Alcudia EVA PA 538 69%* 1 Elvaloy 4170 10%* 2 carbonate 20%* 2 catalyst ** 3 Peroxan HX 45P  1%* *% of the total weight/ ** this parameter is variable

(22) The two EVA polymers were mixed in a kneader at 100° C. for 20 minutes. Once the mixture was homogeneous, the mixture was cooled to 90° C. and the carbonate was slowly added. It took between 10 and 120 minutes for the carbonate to be added (depending on the viscosity of the carbonate). Once all of the carbonate had been added, the mixture was mixed until it was homogeneous. The catalyst was then added and mixed therein for 15 minutes at 90° C. The mixture was then cooled and Peroxan HX 45P was added and mixed for 5 minutes at 80° C. The mixture obtained is typically white (if the catalyst is colorless).

(23) This mixture was then pressed at 80° C. with a force of 5 kN for 15 minutes and then for a further 15 minutes at 15° C. Plates having a thickness of 6 mm were obtained.

(24) Some catalysts were tested by means of DSC and those that resulted in the best expansion in epoxide formulations were tested further in the EVA recipe comprising the D.E.R. 331 carbonate.

(25) Iron(II)sulfate heptahydrate was obtained from the applicant. Cobalt(II) acetylacetonate, copper(II) acetylacetonate and zinc(II) acetylacetonate hydrate was obtained from Sigma-Aldrich.

(26) TABLE-US-00007 TABLE 7 Expansion formulation comprising a carbonate and catalyst Loss in Density Volume Catalyst mass before after expansion iron(II)sulfate heptahydrate −0.87%, 0.9923 0.7809 +139.63% (FeSO.sub.4 × 7H.sub.2O) cobalt(II)acetylacetonate −1.82%, 0.987 0.5032 +197.49% (Co(acac).sub.2) copper(II)acetylacetonate −3.48%, 0.996 0.2423 +420.58% (Cu(acac).sub.2) zinc(II)acetylacetonate −3.00%, 0.9478 0.4274 +244.82% hydrate (Zn(acac).sub.2 × H.sub.2O) Blowing agent: carbonate synthesized from D.E.R. 331, together with 5 mol. % of catalyst Hardening at 180° C. for 20 minutes

(27) Copper(II)acetylacetonate (Cu(acac).sub.2) was the catalyst that resulted in the greatest volume increase for the carbonate from D.E.R. 331, with 420% expansion at 180° C.