Patent Description:
Foaming materials have been widely used in noise control applications at many places in automotive, airplanes as well as building acoustics.

For the application in automotive, normally a foaming article made from a foaming composition comprising foaming material, such as ethylene-vinyl acetate (EVA) copolymer, is heated at a baking window from <NUM> to <NUM> depending on the production line of the automotive. The foaming article made from the existing foaming composition exhibits good volume expansion during the current foaming process. However, the current baking window requires high energy inputs and does not meet with the global trend of energy saving.

<CIT> discloses a thermally expandable composition that shows excellent properties in terms of expansion stability over a wide temperature range and that can be expanded at temperatures below <NUM> and is especially suitable for baffle and/or reinforcement elements. The composition comprises a crosslinkable polymer, an antioxidant, a chemical blowing agent and a specific activator.

Therefore, there is a need for developing a foaming composition, and a foaming article made from the foaming composition which is able to expand sufficiently at a lower temperature baking window from <NUM> to <NUM>. The foaming article is desired to be also applicable to the existing automotive production lines with the baking window from <NUM> to <NUM>.

The present invention relates to a foaming composition, comprising:.

wherein the content of the crosslinking enhancer is from <NUM> to <NUM>% by weight based on the total weight of the composition.

A foaming article made from the foaming composition exhibits high initial volume expansion ratio at the baking window from <NUM> to <NUM> and shows excellent stability after storage under a condition of <NUM> and <NUM>% RH for <NUM> months.

The present invention also relates to a foaming article made by curing the foaming composition in the temperature range of <NUM> to <NUM>, and preferably in the temperature range of <NUM> to <NUM>.

The present invention also relates to a foaming article made from the foaming composition by the steps of:.

The present invention also relates to a foamed article made from the foaming composition.

The present invention also relates to a foamed article made from the foaming article.

The present invention also relates to a vehicle comprising a vehicle part filled with the foamed article, wherein the vehicle part may be a pillar, a door or a vehicle body.

In the following passages the present invention is described in more detail. Each aspect so described may be combined with any other aspect or aspects unless clearly indicated to the contrary. In particular, any feature indicated as being preferred or advantageous may be combined with any other feature or features indicated as being preferred or advantageous.

In the context of the present invention, the terms used are to be construed in accordance with the following definitions, unless a context dictates otherwise.

The terms "comprising", "comprises" and "comprised of" as used herein are synonymous with "including", "includes" or "containing", "contains", and are inclusive or open-ended and do not exclude additional, non-recited members, elements or process steps.

The EVA copolymer of the present invention refers to any common EVA copolymer, preferably having a vinyl acetate (VA) content of <NUM>% by weight or more and a melt index of <NUM> to <NUM> grams per <NUM> minutes at <NUM>/<NUM>, and more preferably having a VA content of <NUM>% to <NUM>% by weight and a melt index of <NUM> to <NUM> grams per <NUM> minutes at <NUM>/<NUM> measured by ASTM D1238. Examples of commercially available EVA copolymers are, for example, Elvax <NUM> from Dupont; Elvax <NUM> from Dupont; and Elvax <NUM> from Dupont.

In some embodiments of the present invention, the amount of EVA copolymer in the foaming composition of the invention is from <NUM>% to <NUM>%, and preferably from <NUM>% to <NUM>% by weight based on the total weight of the composition.

The foaming agent of the present invention refers to any common foaming agent, and may be selected from <NUM>,<NUM>'-oxybis(benzenesulfonyl hydrazide) (OBSH), azodicarbonamide, diisopropyl azodicarboxylate and any combination thereof.

In some embodiments of the present invention, the foaming agent prefers to be OBSH.

Examples of commercially available foaming agents are, for example, OBSH from IMCD Australia Limited; and OBSH from Western Reserve Chemical.

In some embodiments of the present invention, the amount of the foaming agent of the invention is from <NUM> to <NUM>%, and preferably from <NUM> to <NUM>% by weight based on the total weight of the composition.

The peroxide compound of the present invention refers to any common peroxide compound and preferably organic peroxides. The peroxide compound functions as a crosslinking agent for the crosslinking of EVA copolymer.

Examples of the peroxide compounds include but not limited to <NUM>,<NUM>-dimethyl-<NUM>,<NUM>-di(tert-butylperoxy) hexane, tert-butyl peroxybenzoate, benzoyl peroxide, di(tert-butylperoxyisopropyl) benzene, dicumyl peroxide, <NUM>,<NUM>-di(t-butylperoxy)-<NUM>,<NUM>,<NUM> -trimethylcyclohexane, butyl <NUM>,<NUM>-bis(tert-butyldioxy) valerate and any combination thereof.

Examples of commercially available peroxide compounds, for example, are DCP40 from Arkema; and Varox 231XL from Vanderbilt Chemicals;.

In some embodiments of the present invention, the amount of the peroxide compound is from <NUM> to <NUM>%, preferably from <NUM> to <NUM>% and more preferably from <NUM> to <NUM>% by weight based on the total weight of the composition.

The polyamine of the present invention refers to any common polyamine and functions as a crosslinking agent for the crosslinking of EVA copolymer.

Examples of the polyamine include but not limited to diethyltoluenediamine, chlorodiaminobenzene, diethanolamine, diisopropanolamine, triethanolamine, tripropanolamine, <NUM> ,<NUM>- hexanediamine and any combination thereof.

Commercially available polyamine, for example, is Fujicure-FXR-1090FA from T&K Toka.

In some embodiments of the present invention, the amount of the polyamine is from <NUM>% to <NUM>%, and preferably from <NUM>% to <NUM>% by weight based on the total weight of the composition.

The crosslinking enhancer of the present invention refers to any common crosslinking enhancer which is able to induce foaming at lower temperature. The crosslinking enhancer includes but not limited to trimethylolpropane trimethacrylate, zinc diethyl dithiocarbamate, di(morpholin-<NUM>-yl) disulphide, dipentamethylenethiuram tetrasulfide and any combination thereof.

Examples of commercially available crosslinking enhancers are, for example, SR350 from Sartomer; and VISIOMER TMPTMA from Evonik.

In some embodiments of the present invention, the amount of the crosslinking enhancer is from <NUM>% to <NUM>%, and preferably from <NUM>% to <NUM>% by weight based on the total weight of the composition.

The primary antioxidant of the present invention functions as hydrogen atom donors in the conversion of peroxy radical oxidation intermediates to nonradical hydroperoxides and prevents the EVA copolymer from degradation. The primary antioxidant is a phenolic antioxidant.

In some embodiments of the present invention, the primary antioxidant prefers to be a hindered phenolic antioxidant.

Examples of the primary antioxidants include but not limited to pentaerythrityl-tetrakis[<NUM>-(<NUM>,<NUM>-di-tert-butyl-<NUM>-hydroxyphenyl)-propionate], octadecyl <NUM>-(<NUM>,<NUM>-di-tert-butyl-<NUM>-hydroxyphenyl)propionate, <NUM>,<NUM>'-Bis(<NUM>,<NUM>-di-tert-butyl-<NUM>-hydroxyphenyl)-N,N'-hexamethylenedipropionamide and any combination thereof.

Examples of commercially available primary antioxidants are, for example, Irganox <NUM> from Ciba; Irganox L107 from Ciba; and Irganox L109 from Ciba.

In some embodiments of the present invention, the amount of the primary antioxidant is from <NUM> to <NUM>%, and preferably from <NUM>% to <NUM>% by weight based on the total weight of the composition.

The secondary antioxidant of the present invention is different from the primary antioxidant and works together with the primary antioxidant to further remove the hydroperoxides so that the hydroperoxides will not decompose to form new initiating radicals for oxidation. The secondary antioxidant is selected from a phosphorus containing oxidant, a sulfurous containing oxidant and any combination thereof.

In some embodiments of the present invention, the secondary antioxidant is selected from phosphite, phosphonate and any combination thereof.

Examples of the secondary antioxidants include but not limited to bis(<NUM>,<NUM>-ditertbutylphenyl)pentaerytritol diphosphate, tris(<NUM>,<NUM>-ditert-butylphenyl) phosphite, and combinations thereof.

Commercially available secondary antioxidant, for example, is Irgafos <NUM> from BASF.

In some embodiments of the present invention, the amount of the secondary antioxidant is from <NUM>% to <NUM>%, and preferably from <NUM>% to <NUM>% by weight based on the total weight of the composition.

In some embodiments of the present invention, the foaming composition may further optionally include other additives, such as at least one wax, at least one adhesive promoter, at least one filler, at least one lubricant, at least one dye and any combination thereof.

In some embodiments of the present invention, the foaming composition may optionally include at least one wax. Preferably, the wax is a microcrystalline wax with a melting temperature of <NUM> to <NUM>. Examples of commercially available wax are, for example, Microsere 5999A from The International Group; and BE SQUARE <NUM> Amber Wax from Petrolite Corp.

In some embodiments of the present invention, the foaming composition may optionally include at least one adhesive promoter. The adhesive promoter includes but not limited to terpolymer of ethylene, acrylic ester and maleic anhydride. Examples of commercially available adhesive promoter are, for example, Bondine HX <NUM> Arkema; and Lotader Bondine HX <NUM> from Arkema France INC.

In some embodiments of the present invention, the foaming composition may optionally include at least one filler. The filler includes but not limited to silica, mica, and talc. Commercially available filler is, for example, Talc <NUM> from Beijing Lanning Talc factory.

In some embodiments of the present invention, the foaming composition may optionally include at least one lubricant. The lubricant includes but not limited to fatty alcohols and their dicarboxylic acid esters, fatty acid esters of short-chain alcohols, fatty acids, fatty acid amides. Commercially available lubricant is, for example, stearic acid from Changzhou Chemical Co.

In some embodiments of the present invention, the foaming composition may optionally include at least one dye. Preferably, the dye is carbon black. Commercially available dye is, for example, Monarch <NUM> from Cabot corporation.

In a preferred embodiment, the foaming composition comprises:.

A foaming article of the present invention may be made by curing the foaming composition in the temperature range of <NUM> to <NUM>, and preferably in the temperature range of <NUM> to <NUM>.

In some embodiments of the present invention, the foaming article may be prepared by the steps of:.

A foamed article of the present invention may be prepared by heating the foaming articles in a temperature range from <NUM> to <NUM>. In some embodiments of the present invention, the foaming article may be heated from <NUM> to <NUM> minutes, preferably from <NUM> to <NUM> minutes, and most preferably from <NUM> to <NUM> minutes.

In the present invention, the initial volume expansion ratio (R) of the foaming article may be determined by the steps of:.

In the present invention, the volume expansion ratio (Rs) of the foaming article after storage may be determined by the steps of:.

In the present invention, the change of volume expansion ratio (Rc) of the foaming article after storage may be determined by the steps of:<MAT>.

The foaming article of the present invention has preferably an initial volume expansion ratio (R) equal to or greater than <NUM>% after being heated at the temperature of <NUM>.

The foaming article of the present invention has preferable an initial volume expansion ratio (R) equal to or greater than <NUM>% after being heated at the temperature of <NUM>.

The foaming article of the present invention has preferable a volume expansion ratio (Rs) greater than or equal to the initial volume expansion ratio (R) after being stored under a condition of <NUM> and <NUM>% RH for <NUM> months.

The foaming article of the present invention has preferable a change of volume expansion ratio (Rc) of at least <NUM>%, at least <NUM>%, at least <NUM>%, or at least <NUM>% when the foaming article is stored under a condition of <NUM> and <NUM>% RH for <NUM> months and then heated at the temperature of <NUM>.

The present invention will be further described and illustrated in detail with reference to the following examples. The examples are intended to assist one skilled in the art to better understand and practice the present invention, however, are not intended to restrict the scope of the present invention. All numbers in the examples are based on weight unless otherwise stated.

The initial volume expansion ratio (R) of the foaming article was obtained by:.

The volume expansion ratio (Rs) of the foaming article after storage was obtained by:.

The change of volume expansion ratio (Rc) of the foaming article after storage was calculated by the formula of Rc=(Rs-R)/R;.

Foaming composition samples were prepared according to Table 1A and 1B, by mixing the components selected from:.

In Table 2A, 2B, 3A and 3B, the performance of the foaming articles made from the foaming compositions in Example <NUM> to <NUM> Examples <NUM>-<NUM> are comparative examples respectively without polyamine, primary and secondary antioxydants. All of the foaming articles obtained in Example <NUM> to <NUM> had high initial volume expansion ratio (R) in the baking window of <NUM> to <NUM> and showed good stability after <NUM> months' storage under a condition of <NUM> and <NUM>% RH.

When the content of the crosslinking enhancer was high as shown in Example <NUM>, the foaming article was not expanded sufficiently across the baking window of <NUM> to <NUM> compared with the foaming articles in Example <NUM> to <NUM>.

When only a peroxide compound or a polyamine was presented in the foaming composition as shown in Examples <NUM> and <NUM>, the foaming articles made from the foaming compositions expanded to a less extent across the baking window of <NUM> to <NUM> compared with the foaming articles obtained in Example <NUM> to <NUM>. Furthermore, the volume expansion ratio (Rs) of the foaming articles in Example <NUM> and <NUM> was smaller than the initial volume expansion ratio (R) after <NUM> months' storage under a condition of <NUM> and <NUM>% RH.

When only the primary or secondary antioxidant was presented in the foaming composition as shown in Examples <NUM> and <NUM>, (comparative examples) the foaming articles made from the foaming compositions expanded to a less extent across the baking window of <NUM> to <NUM> compared with the foaming articles obtained in Example <NUM> to <NUM>. Furthermore, the volume expansion ratio (Rs) of the foaming articles in Example <NUM> and <NUM> was smaller than the initial volume expansion ratio (R) after <NUM> months' storage under a condition of <NUM> and <NUM>% RH.

It was found that the volume expansion ratio (Rs) of the foaming articles after storage in Example <NUM> to <NUM> was at least the same of the initial volume expansion ratio (R) indicating that the foaming articles were stable after <NUM> month's storage under the condition of <NUM> and <NUM>% RH. It was further found that the volume expansion ratio (Rs) of the foaming article after storage was significantly larger than the initial volume expansion ratio (R) when the foaming articles were heated at the temperature of <NUM> in Example <NUM> to <NUM> as shown in Table <NUM>. For instance, the change of volume expansion ratio (Rc) of the foaming article after storage could reach up to <NUM>% in Example <NUM>. This suggested that the foaming article made by the foaming composition in the present invention could be stored for a much longer time if the foaming article was to be heated at the temperature of <NUM>.

Claim 1:
A foaming composition comprising:
(a) at least one ethylene-vinyl acetate (EVA) copolymer;
(b) at least one foaming agent;
(c) at least one peroxide compound;
(d) at least one polyamine;
(e) at least one crosslinking enhancer;
(f) at least one primary antioxidant, the primary antioxidant being a phenolic antioxidant; and
(g) at least one secondary antioxidant, the auxiliary antioxidant being selected from phosphorus-containing antioxidants, sulfur-containing antioxidants, and any combination thereof;
wherein the content of the crosslinking enhancer is from <NUM> to <NUM>% by weight based on the total weight of the composition.