Expandable rubber composition, its column filler and method of using the same

Abstract

The present invention relates to an expandable rubber composition comprising at least one rubber, a toughener, a filler, a blowing agent, a curing agent and an adhesion promoter, wherein the adhesion promoter comprises a maleic anhydride modified rubber, and related methods of use thereof. The expandable rubber composition is capable of being used as a pillar filler (e.g., in automotive industry applications) after curing and foaming, which provides high curing rate and expansion rate at low curing temperature, good foaming performance, excellent strength and bonding performance after curing. The pillar filler has good corrosion resistance and can be used for cavity filling.

Description

Technical Field

[0001] This disclosure relates to expandable rubber compositions for low-temperature curing, their pillar fillers and components, and related methods of use. The expandable rubber compositions and pillar fillers can be used, for example, in the automotive industry for sealing cavities. Background Technology

[0002] In recent years, expandable resins have been developed for filling or sealing hollow components (e.g., vehicles), thereby reducing noise and preventing vibration in such vehicles. For example, these expandable resins are used to manufacture parts with predetermined shapes (sometimes referred to by those skilled in the art as sound insulation panels or cavity filler inserts) and placed in the hollow cavities of a vehicle, after which the expandable resin expands to fill or seal the cavity. Expandable resin formulations developed for these applications are commonly referred to as column fillers.

[0003] For pillar filler applications, the material is typically provided in extruded form on a metal or plastic carrier, which is then clamped or attached to a suitably designed location within the vehicle body. During subsequent electrophoretic coating and baking processes, the material expands and cures to form a sound-absorbing barrier layer, improving the noise, vibration, and harshness (NVH) performance of the vehicle or system. Therefore, it requires a high expansion rate to fill cavities and good adhesion to the metal to ensure it does not fall off during curing and foaming. Furthermore, pillar fillers need to provide excellent resistance to common corrosive conditions, such as salt spray and cyclic corrosion testing.

[0004] Since some OEMs have found that the temperature of the cavity is always lower than that of the electrophoretic coating, and require expandable compositions that have both a fast curing rate and a high expansion rate under low-temperature curing conditions, they can reduce rework caused by sagging. Summary of the Invention

[0005] Therefore, the object of this invention is to overcome the above-mentioned disadvantages by providing a high-performance, expandable, rubber-based column filler composition that exhibits high curing rate and expansion rate at low curing temperatures, good foaming properties, and excellent strength and adhesion after curing. This column filler also has good corrosion resistance and can be used for cavity filling.

[0006] According to one aspect, the present invention relates to an expandable rubber composition comprising: a) At least one type of rubber, b) Toughening agents, c) At least one filler comprising active zinc oxide. d) Foaming agent, e) Curing agent, and f) Adhesion accelerators, The adhesion promoter mentioned above comprises maleic anhydride-modified rubber.

[0007] According to one aspect, the present invention relates to a method of using an expandable rubber composition, the method comprising: a) Applying an expandable rubber composition of at least one embodiment of the present invention to at least one substrate of an article having cavities or gaps; b) Curing and foaming the expandable rubber composition in the article at a temperature of 120°C to 220°C for at least 15 to 50 minutes to fill the cavity or gap.

[0008] According to another aspect, the present invention also relates to column fillers comprising cured and foamed products of expandable rubber compositions according to the present invention.

[0009] In another aspect, the present invention relates to an article comprising a cavity or gap and a cured / foamed composition disposed between and adhered to the cavity or gap of the article, wherein the cured / foamed composition is a cured / foamed product of an expandable rubber composition according to the present invention.

[0010] According to another aspect, the present invention also relates to an automobile frame, the automobile frame including the articles of the present invention. Attached Figure Description

[0011] Figure 1 The corrosion resistance test results for samples E1 and CE1 are shown. Detailed Implementation

[0012] The invention is described in more detail in the following paragraphs. Unless explicitly stated otherwise, each aspect thus described may be combined with one or more other aspects. In particular, any feature indicated as preferred or advantageous may be combined with one or more other features indicated as preferred or advantageous.

[0013] In the context of this invention, unless the context otherwise requires, the terminology used will be interpreted according to the following definitions.

[0014] Unless the context clearly specifies otherwise, the singular forms “a / an” and “the” as used herein include both the singular and plural references. For example, references to “filler” cover embodiments having one, two, or more fillers. Unless the content clearly specifies otherwise, the term “or” as used in this specification and the appended claims is generally used in its meaning including “and / or”.

[0015] As used herein, the term “comprising / comprises / comprised of” is synonymous with “including / includes” or “containing / contains”, and is inclusive or open-ended, and does not exclude additional undescribed members, elements, or method steps.

[0016] The term "room temperature" refers to a temperature in the range of 20°C (inclusive) to 25°C (inclusive).

[0017] The definition of numerical endpoints includes all numbers and fractions falling into their respective ranges, as well as the listed endpoints.

[0018] Unless otherwise defined, all terms used in this disclosure (including technical and scientific terms) have the meanings commonly understood by one of ordinary skill in the art to which this invention pertains. Further guidance includes terminology definitions to better understand the teachings of this invention.

[0019] In the context of this disclosure, several terms will be used.

[0020] The term "polymer" as used herein is consistent with its common usage in chemistry. A polymer is composed of many repeating subunits. The term "polymer" is used to describe materials obtained from polymerization reactions.

[0021] As used in this article, “curing” means exposure to any form of radiation, heating, or physical or chemical reaction that causes hardening or increased viscosity.

[0022] The "D" used in this article 50 "Particle size" means that the particle size distribution is such that at least 50% by weight of the particles have a diameter smaller than a specified value. Unless otherwise stated, particle size is determined by laser diffraction.

[0023] The "M" used in this article w"" refers to the weight-average molecular weight and means the theoretical value determined by gel permeation chromatography (GPC) relative to linear polystyrene standards from 1.1 M to 580 Da, and can be performed using the Waters 2695 separation module with a Waters 2414 differential refractometer (RI detector).

[0024] As discussed above, embodiments of this disclosure relate to expandable rubber compositions comprising at least an epoxy resin; a toughening agent; an accelerator; a foaming agent; and a curing agent.

[0025] rubber The formulations according to the invention comprise at least rubber, including solid rubber and / or liquid rubber. Natural rubber and / or synthetic rubber are suitable for use in this invention.

[0026] Examples of suitable rubbers are: polybutadiene, preferably having a very high proportion (typically above 95%) of cis-1,4 double bonds; styrene-butadiene rubber, such as styrene-butadiene-styrene copolymer (SBS) or styrene-butadiene terpolymer (e.g., styrene-isoprene-butadiene polymer); butadiene-acrylonitrile rubber; styrene-isoprene rubber, such as benzene-isoprene-styrene copolymer (SIS) or styrene-isoprene terpolymer; styrene-ethylene / propylene-styrene copolymer (SEPS), styrene-ethylene / ethylene / propylene-styrene copolymer (SEEPS); synthetic or natural isoprene rubber; polycyclooctenamene; butyl rubber; or polyurethane rubber.

[0027] In some embodiments, the solid rubber is selected from styrene-butadiene rubber and styrene-isoprene rubber, particularly from styrene-butadiene polymers and styrene-isoprene block copolymers, and especially preferably from styrene-butadiene polymers. The solid rubber particularly has a weight-average molecular weight greater than 100,000 g / mol.

[0028] In some embodiments, the liquid rubber is selected from butadiene-isoprene rubber and styrene-butadiene rubber, especially butadiene-isoprene rubber. The liquid rubber particularly has a weight-average molecular weight of less than 100,000 g / mol, especially less than 70,000 g / mol. The weight-average molecular weight range of the liquid rubber is preferably 2,000 to 100,000 g / mol, especially 5,000 to 70,000 g / mol, more preferably 10,000 to 50,000 g / mol.

[0029] In some embodiments, the rubber content in the expandable rubber composition is preferably 15 to 60 parts by weight, or 15 to 55 parts by weight, or 20 to 55 parts by weight, or 20 to 45 parts by weight, or 25 to 50 parts by weight, or 15 to 45 parts by weight, based on the total weight of the formulation.

[0030] toughening agent The expandable rubber composition of the present invention contains at least a toughening agent.

[0031] In some implementations, the toughening agent comprises EVA (ethylene-vinyl acetate) resin and petroleum hydrocarbon resin.

[0032] Examples of commercially available EVA (ethylene-vinyl acetate) resins include, for example, those sold by DuPont as EvaflexEV 250, Elvas 460, Elvax 3180, Elvax 150W, Elvax 3180Z, Elvax 210W, and Elvax 3182.

[0033] Examples of commercially available petroleum hydrocarbon resins include, for example, DNPR-11 sold as a C-9 resin by Shanghai Daode Trading Co. Ltd, and U 90 and YL 90 sold by YUEN LIANG INDUSTRIAL & CO. LTD.

[0034] In some embodiments, the expandable rubber composition comprises 1 to 20 parts by weight, or 1 to 15 parts by weight, or 1 to 10 parts by weight, or 1 to 8 parts by weight, or 1.5 to 8 parts by weight, or 2 to 8 parts by weight of a toughening agent.

[0035] The expandable rubber composition of the present invention preferably contains at least 1 part by weight, or at least 1.5 parts by weight, or at least 2 parts by weight, or at least 2.5 parts by weight of total toughening agent. The expandable rubber composition of the present invention preferably contains at most 20 parts by weight, or at most 15 parts by weight, or at most 10 parts by weight, or at most 8 parts by weight of total toughening agent. Preferred amounts include 1 to 10 parts by weight, or 2 to 8 parts by weight.

[0036] filler In expandable rubber compositions, fillers are used to increase thixotropy, reduce density, or maintain modulus.

[0037] In some embodiments, the packing material comprises activated zinc oxide. The BET specific surface area (measured with gaseous nitrogen) of the zinc oxide packing is greater than 10 m². 2 / g, or greater than 15 m 2 / g, or greater than 20 m 2 / g, or greater than 25 m 2 / g, or greater than 30 m 2 / g, or greater than 35 m 2 / g, or greater than 38 m 2 / g, or equal to or greater than 40 m 2 / g.

[0038] Commercially available activated zinc oxide includes materials sold by LANXESS under the trademark Bayoxide Z aktiv, and activated zinc oxide filler D. 50 Preferably, the size is from about 0.01 to 500 micrometers. Typically, the composition may contain more than 2 to about 20 parts by weight, or about 2.1 to about 10 parts by weight, or about 2.2 to about 8 parts by weight, or about 2.1 to about 5.5 parts by weight, or about 3 to about 6 parts by weight of active zinc oxide.

[0039] In some embodiments, the loading of active zinc oxide filler may be greater than 2.0 parts by weight, or at least 2.1 parts by weight, or at least 2.2 parts by weight, or at least 2.5 parts by weight, or at least 3.0 parts by weight, or at least 4.0 parts by weight.

[0040] In some embodiments, the compositions of the present invention optionally comprise known fillers, such as various ground or precipitated chalk, quartz powder, alumina, non-flaky clay, dolomite, carbon fiber, glass fiber, polymer fiber, titanium dioxide, calcined silica, fumed silica, carbon black, calcium oxide, calcium carbonate, calcium magnesium carbonate, barite, and talc.

[0041] In other embodiments, calcium carbonate and / or talc, optionally present, are used as fillers in the composition. Commercially available calcium carbonate includes material sold by Perfection Nanometer New Material Co., Ltd. as Calciumcarbonate SPT. The D of the calcium carbonate filler... 50 The diameter is preferably from about 0.01 to 500 micrometers.

[0042] Typically, the composition may contain about 0.1 to about 30 parts by weight, or 10 to about 30 parts by weight, or 15 to about 25 parts by weight of filler.

[0043] curing agent The expandable rubber composition also includes a curing agent system containing at least one peroxide and at least one quinone, quinone dioxime, or dinitrobenzene. In particular, the combination of a peroxide curing agent with a quinone, quinone dioxime, or dinitrobenzene-based curing agent produces excellent expansion properties while resulting in good adhesion and elasticity of the resulting foam. This combination achieves a good balance where the formulation does not harden too rapidly. If the formulation hardens too rapidly, the surface will crack during expansion, and the foam will collapse due to gas escape.

[0044] In some embodiments, the content of the curing agent system is preferably 0.1 to 10 parts by weight, or 0.1 to 5 parts by weight, or 0.1 to 3 parts by weight, or 0.5 to 3 parts by weight, based on the total weight of the composition.

[0045] In particular, organic peroxides (e.g., ketone peroxides, diacyl peroxides, peresters, perketals, and hydrogen peroxide) are preferred according to the present invention. Particularly preferred are, for example, hydroperoxide cumene, tert-butyl peroxide, bis(tert-butylperoxide)diisopropylbenzene, bis(tert-butylperoxide isopropyl)benzene, diisopropylbenzene peroxide, tert-butyl peroxybenzoate, dialkyl percarbonate, diperoxyketal (e.g., 1,1-di-tert-butylperoxide-3,3,5-trimethylcyclohexane), ketone peroxides (e.g., methyl ethyl ketone peroxide), 4,4-di-tert-butylperoxide-n-butylvalerate, and trioxepane (e.g., 3,3,5,7,7-pentamethyl-1,2,4-trioxepane).

[0046] According to the invention, particularly preferred peroxides are those commercially available from Akzo Nobel or Pergan, such as 3,3,5,7,7-pentamethyl-1,2,4-trioxane, 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane, di-tert-butylperoxide, 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane, tert-butyl cumene peroxide, bis(tert-butylperoxide isopropyl)benzene, dicumene peroxide, 4,4-bis(tert-butylperoxide)valerate, tert-butyl peroxide-2-ethylhexyl carbonate, 1,1-bis-(tert-butylperoxide)-3,3,5-trimethylcyclohexane, tert-butyl peroxide, di-(4-methylbenzoyl)peroxide, and dibenzoyl peroxide. According to the present invention, bis(tert-butylperoxyisopropyl)benzene, bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane and / or diisopropylbenzene peroxide are particularly preferred as peroxides.

[0047] It has also been found that, according to the invention, it is advantageous that the peroxide used is substantially inert at room temperature and is only activated when heated to relatively high temperatures (e.g., when heated to temperatures between 120°C and 140°C). According to the invention, it is particularly advantageous that the peroxide used has a half-life of 60 minutes at or below 130°C, meaning that after heating the thermally expandable formulation containing said peroxide to 130°C for 60 minutes, more than half of the peroxide used has decomposed. According to the invention, such a peroxide having a half-life of 60 minutes at or below 115°C is particularly preferred.

[0048] In addition, various peroxides can be used in combination, especially those mentioned above as preferred.

[0049] In some embodiments, the peroxide content is preferably greater than 0.2 parts by weight and less than 0.6 parts by weight, or 0.21 to 0.59 parts by weight, or 0.22 to 0.58 parts by weight, or 0.25 to 0.55 parts by weight, or 0.25 to 0.58 parts by weight, or 0.25 to 0.5 parts by weight, based on the total weight of the formulation.

[0050] In addition, the curing agent system also contains at least one quinone, quinone dioxime, or dinitrosylbenzene, especially 1,4-benzoquinone dioxime, nitrosylbenzene, or dinitrosylbenzene, especially 1,4-benzoquinone dioxime.

[0051] In some embodiments, the range of quinone, quinone dioxime, or dinitrosobenzene (especially 1,4-benzoquinone dioxime) is preferably 0.1 to 3 parts by weight, more preferably 0.1 to 2 parts by weight, based on the total weight of the formulation.

[0052] In some embodiments, in addition to peroxide curing agents, sulfur is also used as a curing agent in the following ranges: greater than 0.5 to less than 2.5 parts by weight, or greater than 0.5 to 2.4 parts by weight, or 0.55 to 2.4 parts by weight, or 0.6 to 2.2 parts by weight, or 0.6 to 2 parts by weight, preferably 0.6 to 1.5 parts by weight.

[0053] Adhesion promoter Adhesion promoters are necessary for this invention, as they help improve adhesive properties.

[0054] Suitable adhesion promoters include maleic anhydride-modified rubbers. Maleic anhydride-modified rubbers include maleic anhydride adducts of polybutadiene, maleic anhydride adducts of polypentadiene, maleic anhydride adducts of nitrile butadiene, and their derivatives. Surprisingly, maleic anhydride-modified rubber adhesion promoters have been found to work in conjunction with peroxide curing agents to achieve both good anti-sagging and foam expansion rates.

[0055] In some embodiments, suitable adhesion promoters include maleic anhydride adducts of low molecular weight cis-1,4-polybutadiene having succinic anhydride groups randomly distributed along the polymer chain.

[0056] Commercially available examples of adhesion promoters include LITHENE ULTRA AL-15MA from Synthomer and Polyvest MA 75 from Evonik.

[0057] Typically, the composition may contain more than 1 part by weight to about 10 parts by weight, or about 1.1 to about 8 parts by weight, or about 1.2 to about 6 parts by weight, or about 1.1 to about 5 parts by weight, or about 1.2 to about 5 parts by weight of an adhesion promoter.

[0058] In some embodiments, the loading of the adhesion promoter may be at least 1.0 parts by weight, or at least 1.2 parts by weight, or at least 1.5 parts by weight, or at least 1.8 parts by weight, or at least 2.0 parts by weight, or at least 2.8 parts by weight, or at least 3.5 parts by weight, or at least 4.0 parts by weight, or at least 4.5 parts by weight.

[0059] foaming agent As another essential component for this invention, the heat-expandable rubber composition according to the invention comprises a heat-activated foaming agent. Suitable heat-activated foaming agents are, in principle, all known foaming agents, such as "chemical foaming agents" or "physical foaming agents" that decompose and release gas upon heat treatment (especially heat-expandable hollow spheres). According to the invention, chemical foaming agents are preferred.

[0060] According to the present invention, chemical foaming agents should be understood to mean compounds that decompose upon exposure to heat and thereby release gas.

[0061] Examples of suitable chemical foaming agents are azo compounds, hydrazide compounds, nitroso compounds, and carbachol compounds, such as azobisisobutyronitrile, azodicarbonamide (ADCA), dinitrosopentamethylenetetramine (DNPT), 4,4'-oxobis(benzenesulfonylhydrazine) (OBSH), 4-methylbenzenesulfonylhydrazine, azocyclohexylnitrile, azodiaminobenzene, benzene-1,3-sulfonylhydrazine, benzene-4-sulfonylhydrazine (BSH), calcium azide, 4,4'-diphenyldisulfonyl azide, diphenyl sulfone-3,3'-disulfonylhydrazine, diphenyl ether-4,4'-disulfonylhydrazine, benzene-1,3-disulfonylhydrazine, trihydrazine triazine, 5-phenyltetrazole (5-PT), p-toluenesulfonylhydrazine (TSH), and p-toluenesulfonamide urea (PTSS).

[0062] Another suitable type of foaming agent is H-silane, which is marketed by Huntsmann, for example, under the trade name Foaming Agent DY-5054.

[0063] Furthermore, the carbamates described in DE-A1-102009029030 are particularly suitable as chemically thermally activated foaming agents within the scope of this invention.

[0064] Endothermic chemical foaming agents (especially those selected from bicarbonates, optional functionalized polycarboxylic acids and salts of solid form, and mixtures thereof) are also suitable. These endothermic foaming agents have the advantage of being both harmless to health and non-explosive, and they form fewer volatile organic compounds (VOCs) during expansion. The decomposition products are primarily CO2 and water. Furthermore, products manufactured using them exhibit a more uniform foam structure across the entire process temperature range used for curing. This can also result in lower water absorption. Finally, the decomposition temperature of endothermic foaming agents (especially mixtures thereof) is lower than that of conventional exothermic foaming agents, thus allowing for lower process temperatures and energy savings.

[0065] Suitable bicarbonates are those of the formula XHCO3, where X can be any cation, especially an alkali metal ion, preferably Na. + or K + Na + It is extremely preferred. Another suitable cation X + It can be selected from NH4 + ½Zn 2+ ½ Mg 2+ ½ Ca 2+ , and their mixtures.

[0066] Suitable polycarboxylic acids include, but are not limited to, solid organic diacids, tricids, or tetracids, especially hydroxyl-functionalized or unsaturated dicarboxylic acids, tricarboxylic acids, tetracarboxylic acids, or polycarboxylic acids, such as citric acid, tartaric acid, malic acid, fumaric acid, and maleic acid. Citric acid is particularly preferred. Therefore, citric acid is advantageous, especially because it is an eco-sustainable blowing agent.

[0067] When using polycarboxylic acids, carbonates are also preferred. Mixtures of bicarbonates, carbonates, and polycarboxylic acids are preferred, thereby allowing for targeted setup of different activation stages and decomposition reactions.

[0068] According to the invention, in each case, based on the total applied formulation, the content of the chemically thermally activated blowing agent is preferably 0.1 to 20% by weight, particularly 0.2 to 15% by weight, more preferably 0.5 to 10.0% by weight. Particularly preferred is the inclusion of sulfonyl hydrazide (especially OBSH) and / or azodicarbonate as at least one blowing agent; in each case, based on the total weight of the formulation, sulfonyl hydrazide and / or azodicarbonate.

[0069] According to the present invention, it is preferable to use a combination of at least one chemically heat-activated blowing agent and at least one physically heat-activated blowing agent in the heat-expandable formulation.

[0070] The amount of foaming agent is preferably selected such that the volume of the thermally expandable compound irreversibly increases by at least 10%, preferably at least 50%, and especially at least 100% when heated to the activation temperature (or expansion temperature). This means that, in addition to normal and reversible thermal expansion according to the compound's coefficient of thermal expansion, the volume of the compound at the activation temperature, compared to its initial volume at room temperature (20°C), causes it to cool. Upon returning to room temperature, it irreversibly increases in such a way that it is at least 10%, preferably at least 50%, and especially at least 100% larger than before. Therefore, the specified degree of expansion refers to the volume of the compound at room temperature before and after it is temporarily heated to the activation temperature.

[0071] The activation temperature in the composition of the present invention is preferably in the range of 120 to 220°C or 140 to 210°C. This temperature should preferably be maintained for a period of 10 to 50 minutes, 15 to 50 minutes, or 15 to 40 minutes.

[0072] Preparation method of expandable rubber composition The method according to the invention also includes obtaining (e.g., manufacturing; purchasing; mixing components of a 1K expandable rubber composition; etc.) the column filler according to the invention, and exposing the expandable rubber composition to conditions to partially or completely cure the epoxy adhesive composition to form the column filler.

[0073] Curing / foaming method for expandable rubber compositions In some embodiments of the invention, the expandable rubber composition is in a liquid phase at room temperature prior to curing and foaming. The expandable rubber composition is preferably cured via the following steps: a) Processing cold-rolled steel (CRS) samples, b) Apply the expandable rubber composition to the treated surface of the sample. c) Allow the sample to cure at a certain temperature for a certain time.

[0074] List of Implementation Plans 1. An expandable rubber composition, said expandable rubber composition comprising: a) At least one type of rubber, b) Toughening agents, c) At least one filler comprising active zinc oxide. d) Foaming agent, e) Curing agent, and f) Adhesion accelerators, The adhesion promoter mentioned above comprises maleic anhydride-modified rubber.

[0075] 2. The expandable rubber composition according to embodiment 1, wherein the adhesion promoter comprises a maleic anhydride adduct of polybutadiene, a maleic anhydride adduct of polypentadiene, or a maleic anhydride adduct of nitrile.

[0076] 3. The expandable rubber composition according to any one of the foregoing embodiments, wherein the adhesion promoter comprises a maleic anhydride adduct of cis-1,4-polybutadiene.

[0077] 4. The expandable rubber composition according to any one of the foregoing embodiments, wherein the expandable rubber composition comprises more than 1 to 10 parts by weight or 1.1 to 5 parts by weight of the adhesion promoter.

[0078] 5. The expandable rubber composition according to any one of the foregoing embodiments, wherein the curing agent comprises at least one selected from peroxides, sulfur, and combinations thereof.

[0079] 6. The expandable rubber composition according to any one of the foregoing embodiments, wherein the expandable rubber composition comprises 0.5 to 3 parts by weight of the curing agent.

[0080] 7. The expandable rubber composition according to any one of the foregoing embodiments, wherein the curing agent comprises a peroxide having a half-life of 60 minutes at or below 130°C.

[0081] 8. The expandable rubber composition according to any one of the foregoing embodiments, wherein the curing agent comprises a peroxide having a half-life of 60 minutes at or below 115°C.

[0082] 9. The expandable rubber composition according to any one of the foregoing embodiments, wherein the expandable rubber composition comprises more than 0.2 parts by weight to less than 0.6 parts by weight, or 0.25 to 0.5 parts by weight of a peroxide curing agent.

[0083] 10. The expandable rubber composition according to any one of the foregoing embodiments, wherein the expandable rubber composition comprises more than 0.5 parts by weight to less than 2.5 parts by weight, or 0.6 to 2 parts by weight, or 0.6 to 1.5 parts by weight of a sulfur curing agent.

[0084] 11. The expandable rubber composition according to any one of the foregoing embodiments, wherein the toughening agent comprises one or more selected from EVA resin and petroleum hydrocarbon resin.

[0085] 12. The expandable rubber composition according to any one of the foregoing embodiments, wherein the BET specific surface area of ​​the active zinc oxide, measured with gaseous nitrogen, is greater than 10 m². 2 / g, or greater than 25 m 2 / g.

[0086] 13. The expandable rubber composition according to any one of the foregoing embodiments, wherein the BET specific surface area of ​​the active zinc oxide, measured with gaseous nitrogen, is greater than 35 m². 2 / g, or greater than 40 m 2 / g.

[0087] 14. The expandable rubber composition according to any one of the foregoing embodiments, wherein the expandable rubber composition comprises more than 2 parts by weight to 20 parts by weight, or 2.1 to 10 parts by weight, or 2.1 to 5.5 parts by weight of the active zinc oxide filler.

[0088] 15. The expandable rubber composition according to any one of the foregoing embodiments, wherein the filler further comprises one or more selected from: ground or precipitated chalk, quartz powder, alumina, non-flaky clay, dolomite, carbon fiber, glass fiber, polymer fiber, titanium dioxide, calcined silica, fumed silica, carbon black, calcium oxide, calcium carbonate, calcium magnesium carbonate, barite, talc.

[0089] 16. A method of using an expandable rubber composition, the method comprising: a) Applying the expandable rubber composition according to any one of the foregoing embodiments to at least one substrate of an article having cavities or gaps; b) Curing and foaming the expandable rubber composition in the article at a temperature of 120°C to 220°C for at least 15 to 50 minutes to fill the cavity or gap.

[0090] 17. The method according to embodiment 16, wherein the expandable rubber composition is cured and foamed at a temperature of 140°C to 210°C for at least 15 to 40 minutes to fill the cavity or the gap.

[0091] 18. The method according to embodiment 16, wherein the substrate of the article is metal.

[0092] 19. A column filler comprising a cured and foamed product of an expandable rubber composition according to any one of embodiments 1-15.

[0093] 20. An article comprising a cavity or gap and a cured / foamed composition disposed between and adhered to the cavity or gap of the article, wherein the cured / foamed composition is a cured / foamed product of an expandable rubber composition according to any one of embodiments 1-15.

[0094] 21. A vehicle frame, the vehicle frame comprising the article according to embodiment 20.

[0095] Example The invention will be further described and illustrated in detail below with reference to the embodiments. These embodiments are intended to help those skilled in the art better understand and practice the invention, but are not intended to limit the scope of the invention. Unless otherwise stated, all figures in the embodiments are based on weight.

[0096] raw material

[0097] Example 1 <Preparation of Expandable Rubber Compositions> To prepare the expandable rubber composition E1, all rubber, EVA resin, and C9 resin were added to a kneader and stirred for 30 minutes to form spherical particles. Then, talc, ZnO, CaCO3, stearic acid, plasticizer, and antioxidant were added to the kneader and stirred for another 30 minutes, maintaining the temperature below 60°C. The system was then cooled to below 40°C. Next, a foaming agent, curing agent, plasticizer, and adhesion promoter were added to the kneader and stirred for 30 minutes. The mixture was then stirred and vacuum-treated for 30 minutes, with the vacuum level controlled at less than 0.3 MPa, while maintaining the mixture temperature below 40°C.

[0098] <Curing / Foaming of Expandable Rubber Compositions> The sample of galvanized steel (HDG) was cleaned with acetone and wiped with paper towels, then sprayed on one side with 3 g / m 2 Apply a suitable amount of FERROCOTE 61AUS oil. Cut the adhesive to the specified size and carefully attach it to the steel. Allow all samples / adhesive components to cure / foam separately under different curing / foaming conditions: 1. Incubate at 140°C for 15 minutes, and then at room temperature for 24 hours. 2. Incubate at 150°C for 15 minutes, and then at room temperature for 24 hours. 3. Incubate at 160°C for 15 minutes, and then at room temperature for 24 hours. 4. Incubate at 170°C for 20 minutes, and then at room temperature for 24 hours. 5. Set at 200°C for 20 minutes, and then at room temperature for 24 hours.

[0099] Various tests were performed on the cured structural adhesive samples.

[0100] Examples 2-10 and CE1-CE8 Expandable rubber compositions of E2 to E10 and CE1 to CE8 were prepared according to Example 1. The expandable rubber compositions of E2 to E10 and CE1 to CE8 were cured according to Example 1. Further details are listed in the Results section below.

[0101] Test methods <Inflation Rate> The expansion rate of each sample was quantified by measuring the density of a test sample with dimensions of approximately 25 mm × 25 mm and a thickness of 3 mm before and after expansion using the following steps: • Weigh the sample in air and let its mass be M1, then weigh it in water at 23℃ ± 1℃ and let its mass be M'1.

[0102] • Place the sample, which is placed on an anti-stick support, in a ventilated oven previously conditioned at the test temperature for the specified time period for this operation. This information is specified in the reference document.

[0103] • Remove the components from the oven and allow them to cool at ambient temperature for 2 hours.

[0104] • Weigh the sample again in the air, and let its mass be M2. Then weigh it in the water, and let its mass be M'2.

[0105] Note: In all cases, ensure that all air bubbles that may be introduced during various processes are carefully eliminated.

[0106] Curing conditions: 1) At 140℃ for 15 minutes, 2) At 150℃ for 15 minutes, 3) At 160℃ for 15 minutes, 4) At 170℃ for 20 minutes, 5) Set at 200℃ for 20 minutes.

[0107] Record the expansion rate results and categorize them as follows: - Failure: Below 600%; - Pass: 600% or higher; - Good: equal to or greater than 800%; - Excellent: equal to or greater than 850%.

[0108] <Sagging performance> Prepare an oiled metal sheet with an undefined plate configuration using one of CRS, HDG, or EG and a lubricant. Press a piece of material (100 mm × 25 mm × 4 mm) firmly onto the oiled metal sheet. Store the sheet at (23°C ± 5°C) for 24 hours, and then bake it under the following conditions: 140°C for 15 minutes, 150°C for 15 minutes, 160°C for 15 minutes, 170°C for 20 minutes, and 200°C for 20 minutes. During storage and baking, the sheet should be held upright so that the length of the sealant is horizontal. After cooling to (23°C ± 5°C), the applied material should be evaluated. Sagging or slippage is not permitted.

[0109] <Corrosion Resistance Test> The samples used for the "corrosion resistance" test are as follows. They undergo a surface treatment conversion and are then cured in electrophoresis, placed horizontally in the laboratory, and subjected to a defined number of cycles before being placed in a salt spray test. Upon toe-out, bottom corrosion and / or peripheral corrosion are recorded. If the adhesive exhibits cohesive failure greater than 90% of the area, it is marked as having no adhesive loss.

[0110] After the corrosion cycle, the adhesive is removed, and if the substrate of the sample has no corrosion spots, it is marked as non-corroded.

[0111] Good adhesion properties contribute to corrosion resistance, and the water resistance of the adhesive also contributes to corrosion resistance.

[0112] Curing conditions: 15 minutes at 140℃, 15 minutes at 150℃, 15 minutes at 160℃, 20 minutes at 170℃, 20 minutes at 200℃; Sample size before curing: 100 mm × 30 mm × 2 mm; Substrate: steel; Storage: 500 hours in a salt spray chamber.

[0113] Table 1.

[0114] Table 1 shows the compositions of expandable epoxy adhesives E1-E3 and CE1-CE5.

[0115] Table 2

[0116] Table 2 shows the test results for expandable epoxy adhesives E1-E3 and CE1-CE5.

[0117] Table 3

[0118] Table 3 shows the compositions of expandable epoxy adhesives E4-E10 and CE6-CE8.

[0119] Table 4

[0120] Table 4 shows the test results for expandable rubber compositions E4-E10 and CE6-CE8.

[0121] As we can see from the table, the designed adhesion promoters and curing agents facilitate low-temperature curing without sagging and provide high adhesion and corrosion resistance. Furthermore, the formulation exhibits good expansion properties (at least 600% expansion rate).

[0122] As we can see from the table, the designed adhesion promoters and curing agents contribute to low-temperature curing and foaming properties, for example, low-temperature curing at at least 140°C for 15 minutes, and the formulation exhibits good expansion properties (>600% expansion rate). Furthermore, all cured and foamed compositions from E1 to E10 show good anti-sagging results, no corrosion, and no loss of adhesion.

[0123] Compared to E1, CE1 contains zinc oxide filler with a low specific surface area, which has a good expansion rate, but results in poor sagging and adhesion loss. Figure 1 CE1 in the study showed significant adhesion loss and corrosion results.

[0124] CE2 contains a slightly excessive amount of sulfur curing agent. The cured and foamed samples have low expansion rates at 140°C and 200°C and have passed sagging, adhesion and corrosion tests.

[0125] Compared to E1 and E2, CE3 uses a peroxide curing agent with a 60-minute half-life at temperatures above 130°C. Cured and foamed samples of CE3 showed low expansion rates at 140-150°C and passed sagging, adhesion, and corrosion tests.

[0126] As can be seen from CE4, a small amount of adhesion promoter not only resulted in poor sagging at 140-160°C, but also in low expansion rate, adhesion loss and corrosion at 140-150°C.

[0127] Based on the results from CE6, it was found that a smaller amount of active zinc oxide filler resulted in a lower expansion rate at 140°C.

[0128] In addition to insufficient amount of adhesion promoter, CE5 also contains a slightly smaller amount of sulfur curing agent, resulting in worse sag at high temperatures of 170-200°C compared to CE4.

[0129] Insufficient amount of peroxide curing agent in CE7 results in low expansion rate at 140°C to 150°C, poor sagging results, adhesion loss, and corrosion.

[0130] The slightly excessive amount of peroxide curing agent in CE8 resulted in a low expansion rate at 140°C to 150°C and 200°C, but it passed the sagging, adhesion and corrosion tests.

[0131] In Examples 1 to 10, expandable rubber compositions were prepared according to the formulations provided by the present invention. These formulations specifically comprise rubber, toughening agents, fillers, designed adhesion promoters, curing agents, and foaming agents. It can be seen that when the contents of the claimed components of the present invention are within a certain range, the prepared rubber compositions can be cured and foamed at relatively low temperatures (e.g., 140°C to 150°C). Furthermore, the products E1-E10 exhibit good expansion properties (expansion rate >600%), good anti-sagging results, no adhesion loss, and no corrosion.

Claims

1. An expandable rubber composition, said expandable rubber composition comprising: a) At least one type of rubber, b) Toughening agents, c) At least one filler comprising active zinc oxide. d) Foaming agent, e) Curing agent, and f) Adhesion accelerators, The adhesion promoter mentioned above comprises maleic anhydride-modified rubber.

2. The expandable rubber composition according to claim 1, wherein the adhesion promoter comprises a maleic anhydride adduct of polybutadiene, a maleic anhydride adduct of polypentadiene, or a maleic anhydride adduct of nitrile.

3. The expandable rubber composition of claim 1, wherein the adhesion promoter comprises a maleic anhydride adduct of cis-1,4-polybutadiene.

4. The expandable rubber composition of claim 1, wherein the expandable rubber composition comprises more than 1 to 10 parts by weight or 1.1 to 5 parts by weight of the adhesion promoter.

5. The expandable rubber composition according to claim 1, wherein the curing agent comprises at least one selected from peroxides, sulfur, and combinations thereof.

6. The expandable rubber composition according to claim 1, wherein the expandable rubber composition comprises 0.5 to 3 parts by weight of the curing agent.

7. The expandable rubber composition according to claim 1, wherein the curing agent comprises a peroxide having a half-life of 60 minutes at or below 130°C.

8. The expandable rubber composition according to claim 1, wherein the curing agent comprises a peroxide having a half-life of 60 minutes at or below 115°C.

9. The expandable rubber composition according to claim 1, wherein the expandable rubber composition comprises more than 0.2 parts by weight to less than 0.6 parts by weight, or 0.25 to 0.5 parts by weight, of a peroxide curing agent.

10. The expandable rubber composition of claim 1, wherein the expandable rubber composition comprises more than 0.5 parts by weight to less than 2.5 parts by weight, or 0.6 to 2 parts by weight, or 0.6 to 1.5 parts by weight of a sulfur curing agent.

11. The expandable rubber composition according to claim 1, wherein the toughening agent comprises one or more selected from EVA resin and petroleum hydrocarbon resin.

12. The expandable rubber composition according to claim 1, wherein the active zinc oxide has a BET specific surface area greater than 10 m² as measured with gaseous nitrogen. 2 / g.

13. The expandable rubber composition according to claim 1, wherein the active zinc oxide has a BET specific surface area greater than 35 m² as measured with gaseous nitrogen. 2 / g.

14. The expandable rubber composition of claim 1, wherein the expandable rubber composition comprises more than 2 parts by weight to 20 parts by weight, or 2.1 to 10 parts by weight, or 2.1 to 5.5 parts by weight of the active zinc oxide filler.

15. The expandable rubber composition according to claim 1, wherein the filler further comprises one or more selected from the following: ground or precipitated chalk, quartz powder, alumina, non-flaky clay, dolomite, carbon fiber, glass fiber, polymer fiber, titanium dioxide, calcined silica, fumed silica, carbon black, calcium oxide, calcium carbonate, calcium magnesium carbonate, barite, and talc.

16. A method of using an expandable rubber composition, the method comprising: a) Applying the expandable rubber composition according to at least one of claims 1-15 to at least one substrate of an article having cavities or gaps; b) Curing and foaming the expandable rubber composition in the article at a temperature of 120°C to 220°C for at least 15 to 50 minutes to fill the cavity or gap.

17. The method of claim 16, wherein the expandable rubber composition is cured and foamed at a temperature of 140°C to 210°C for at least 15 to 40 minutes to fill the cavity or the gap.

18. The method of claim 16, wherein the substrate of the article is metal.

19. A column filler comprising a cured and foamed product of an expandable rubber composition according to any one of claims 1-15.

20. An article comprising a cavity or gap and a cured / foamed composition disposed between and adhered to the cavity or gap of the article, wherein the cured / foamed composition is a cured / foamed product of an expandable rubber composition according to any one of claims 1-15.

21. A vehicle frame, the vehicle frame comprising the article according to claim 20.

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