Multi-stage processing of sealant materials

Abstract

The present teachings generally relate to sealant compositions adapted for foaming, curing, or some combination thereof, methods of making activatable sealant compositions, and methods of using the same. Activatable sealant compositions include one or more, preferably high softening or melting point, polymeric materials, one or more foaming agents, one or more foaming agent activators, and one or more hydrocarbon resins, and are delivered to an article of manufacture to provide functional attributes such as sealing, baffling, damping, reinforcement, or a combination thereof.

Description

[Technical field]

[0001] The present teachings generally relate to a multi-step processing method and type of composition of activatable sealants that are otherwise activated by heat during formulation using a single-step process. [Background technology]

[0002] For many years, the automotive industry has been concerned with sealing vehicles from noise, fuel fumes, and harsh weather conditions such as rain, snow, excessive heat, and humidity. Proper sealing can isolate the vehicle's interior space from exterior noise, protect interior components such as electronics from moisture and salt, prevent corrosion of components located within the vehicle panel cavities, and aid in the overall comfort of the vehicle. Among the sealing strategies employed in the automotive industry is the use of preformed heat-activated, foamable or non-foamable sealants that may be crosslinkable. These sealants are activated during one or more processing steps used to cure the various layers of paint during the coating of the vehicle. Thus, the heat-reactive sealant must develop adhesion and foamability, as required, at times and temperatures similar to the paint coatings utilized. These times and temperatures typically range from about 20-40 minutes and about 150-200°C, respectively. Thus, the formulation and formation of the sealant must typically be carried out well below these temperature ranges to avoid premature activation (eg, foaming and / or crosslinking) of the sealant material.

[0003] The present teachings provide a multi-step processing method that allows for a wide selection of polymeric materials that may have higher initial compounding temperatures, and thus are not traditionally used for these types of activatable sealants. This may include polymeric materials that are more readily available from lower cost, broader sources, and more diverse sources. In some cases, the polymeric materials may have mechanical and physical properties that are difficult to obtain using traditional ingredients. Furthermore, processing of sealant materials according to the present teachings may allow for the use of polymeric materials that are readily available from recycled, post-industrial, or post-consumer sources. Summary of the Invention [Problem to be solved by the invention]

[0004] In view of the above, it would be desirable to provide a method of forming a foamable / curable sealant composition utilizing a multi-step processing method. It would be desirable to provide a foamable / curable sealant composition that utilizes polymeric materials not previously utilized in the field, allowing for a wider range of sources and a greater variety of polymeric materials to be selected. Additionally, it would be desirable to provide a foamable / curable sealant composition that is less expensive and more environmentally friendly (e.g., by utilizing recycled materials). [Means for solving the problem]

[0005] The present teachings generally relate to foamable / curable sealant compositions that can address one or more of the above needs, including one or more, preferably high softening or melting point, polymeric materials, one or more foaming agents, one or more foaming agent activators, and one or more temperature processing aids, and are delivered to an article of manufacture to provide functional attributes such as sealing, baffling, dampening, reinforcement, or a combination thereof.

[0006] The foamable / curable sealant compositions described herein may include one or more of the following aspects: The foamable / curable sealant compositions may include one or more auxiliary agents, process oils, pigments, and / or inert fillers. The one or more, preferably high softening or melting point, polymeric materials may be derived from recycled, post-industrial or post-consumer sources.

[0007] In one aspect, the teachings herein disclose a foamable / curable sealant composition comprising one or more, preferably high softening or melting point, polymeric materials, one or more blowing agents, one or more blowing agent activators, and one or more temperature processing aids selected from hydrocarbon resins, process oils, waxes, EPDM, liquid elastomers, high melt flow copolymers, or low melting point copolymers, the foamable / curable sealant composition being delivered to an article of manufacture.

[0008] The composition may include a coagent. The coagent may be selected from an acrylate, a methacrylate, or a maleimide. The coagent may be any component that has free radical reactivity.

[0009] The one or more, preferably high softening or melting point, polymeric materials may be selected from high density polyethylene (HDPE), low density polyethylene (LDPE), or linear low density polyethylene (LLDPE). The one or more, preferably high softening or melting point, polymeric materials may be recycled from post-industrial or post-consumer sources. The one or more, preferably high softening or melting point, polymeric materials may comprise at least about 50% or more of the total composition of the foamable / curable sealant.

[0010] The blowing agent or agents may be azodicarbonamide.

[0011] The one or more blowing agent activators may be selected from zinc oxide, dicyandiamide, calcium salts, ureas, or substituted ureas.

[0012] The composition may include a processing oil. The composition may include a pigment. The composition may include an inert filler. The composition may be heat activated.

[0013] The composition may be provided to the article of manufacture as a sheet, strip, patch, ring, disc, or combination thereof. The article of manufacture may be a sealing baffle for a motor vehicle.

[0014] In another aspect, the teachings herein are directed to a multi-step method for processing a foamable / curable sealant composition, comprising, in a first step, combining one or more, preferably high softening or melting point, polymeric materials with one or more modifying components to obtain a resultant first mixture, and, in a second or subsequent step, combining the resultant first mixture with one or more foamable / curable components to obtain a foamable / curable sealant composition. The second or subsequent step may not begin until the temperature of the resultant first mixture falls below the temperature at which the foamable / curable components are activated.

[0015] The second or subsequent steps may be carried out at a lower temperature than the first step. The second or subsequent steps may be for a shorter period of time than the first step.

[0016] The one or more, preferably high softening or melting point, polymeric materials may be selected from high density polyethylene (HDPE), low density polyethylene (LDPE), or linear low density polyethylene (LLDPE). The one or more, preferably high softening or melting point, polymeric materials may be recycled from post-industrial or post-consumer sources. The modifying component may be selected from one or more of low melting point polymeric materials (melting point preferably less than 100° C.), low softening point polymeric materials (softening point preferably less than 100° C.), low molecular weight polymeric materials (molecular weight preferably less than 500 g / mol), waxes, hydrocarbon resins, plasticizers, process oils, or combinations thereof. The foamable / curable component may be selected from one or more of blowing agents, blowing agent activators, coagents, or combinations thereof.

[0017] The teachings herein are further directed to sealant compositions that include one or more, preferably high softening or melting point, polymeric materials, one or more blowing agents, one or more blowing agent activators, and one or more components selected from hydrocarbon resins, processing oils, waxes, EPDM, liquid elastomers, high melt flow copolymers, or low melting point copolymers. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 illustrates a prior art material exposed to extreme humidity. [Figure 2A] FIG. 1 illustrates a material in accordance with the present teachings. [Figure 2B] FIG. 1 illustrates a material in accordance with the present teachings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The explanations and examples provided herein are intended to familiarize others skilled in the art with the teachings, their principles, and their practical applications. Those skilled in the art can adapt and apply the teachings in numerous forms as may best suit the requirements of a particular use. Thus, the specific embodiments of the teachings described are not intended to be exhaustive or limiting of the teachings. Thus, the scope of the teachings should not be determined with reference to the above description, but rather with reference to the appended claims, along with the full scope of equivalents to which the claims are entitled. The disclosures of all articles and references, including patent applications and publications, are incorporated by reference for all purposes. Other combinations are possible, as can be gleaned from the claims below, which are also incorporated by reference herein.

[0020] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 275,164, filed November 3, 2021, the contents of which are incorporated by reference in their entirety for all purposes.

[0021] The present teachings provide a foamable / curable sealant composition, a method of making the foamable / curable sealant composition, and a method of using the same. The foamable / curable sealant composition of the present teachings can be employed to form parts to provide functional attributes such as sealing, baffling, damping, reinforcement, or a combination thereof. The foamable / curable sealant composition can be useful in the construction of articles of manufacture such as buildings, appliances, and / or transportation vehicles (e.g., boats, trains, automobiles).

[0022] Activation of the sealant composition is typically caused by exposure to stimuli such as pressure, moisture, heat, radiation, etc. Activation can cause the sealant composition to undergo chemical and / or physical changes. This can include changes in shape such as flowing, foaming, expanding, etc. This can result in the formation of a physical barrier while exerting adhesion to the substrate and / or sealing of cavities. Preferably, the foamable / curable sealant composition is activated upon exposure to heat. When the foamable / curable sealant composition is heat activated, the heat for activation can be provided from a variety of sources, such as, but not limited to, microwave energy, ionizing radiation, furnaces, thermoelectric devices, electrical energy, chemical reactions, and / or combinations thereof. In a preferred embodiment, the foamable / curable sealant composition is processed with the article of manufacture, and heat is provided by the inherent processing or assembly process employed to make the article. For example, the foamable / curable sealant composition may be applied to the structure of an automotive vehicle and may be activated upon exposure to temperatures frequently encountered in e-coat oven bakes, primer oven bakes, paint oven bakes, combinations thereof, etc. for such automotive vehicles. Typical cure conditions for automotive coatings range from about 150° C. or less to about 200° C. or more, although it would be desirable to reduce these temperatures.

[0023] The foamable / curable sealant composition may undergo crosslinking, which can aid in the entrapment of gas from the foaming agent, aid in the adhesion of the sealant composition to surfaces with which it comes in contact, and / or increase the elastic modulus of the sealant composition so that the material better resists deformation or movement from the position designated to perform its sealing function.

[0024] composition The foamable / curable sealant composition may include a number of different components or ingredients, such as, for example, polymeric materials, copolymeric materials, foaming agents, foaming agent activators, coagents, resins, processing oils, organic peroxides, antioxidants, pigments, fillers, and combinations thereof. The number of different components or ingredients can function to modify one or more physical properties (e.g., melting point, softening point, viscosity) of the polymeric material and / or aid in the activation of the sealant composition.

[0025] The foamable / curable sealant composition may include one or more polymeric materials. The one or more polymeric materials may be amorphous, crystalline, or a combination of both. Suitable amorphous polymeric materials include, but are not limited to, polystyrene, polymethyl methacrylate, and acrylonitrile butadiene styrene. Suitable crystalline polymeric materials for incorporation into the foamable / curable sealant composition include, but are not limited to, polypropylene, polyethylene terephthalate, polybutylene terephthalate, and polyethylene terephthalate glycol.

[0026] Preferably, the foamable / curable sealant composition may contain ethylene homopolymers, copolymers, and / or terpolymers. By way of example, the foamable / curable sealant composition may contain high density polyethylene (HDPE) (density 0.941 to 0.965 g / cm 3 ), low-density polyethylene (LDPE) (density 0.91-0.925g / cm 3 ), copolymers of ethylene and / or linear low density polyethylene (LLDPE) (density 0.91-0.94 g / cm 3The copolymers may contain alpha olefins such as butene, hexene, and octene, also referred to as olefins (e.g., ethylene copolymers). The illustrative examples in Tables 1-4 and 5 show suitable ethylene copolymers with melt flow rates (MFR) ranging from about 7 g / 10 min or less to about 70 g / 10 min or more. Unless otherwise specified, MFR is measured at 190° C. and 2.16 kg according to ISO 1133. For purposes of clarity, melt flow rate (MFR) is used synonymously with melt flow index (MFI).

[0027] One or more polymeric materials included in the foamable / curable sealant composition may exhibit a high softening point or high melting point. High softening and high melting point materials are those with softening and / or melting points between 100 and 120°C. Materials that soften or melt in this range require compounding or processing temperatures approaching those experienced in typical paint baking ovens (e.g., 110-140°C or higher) and are therefore typically not selected for use in materials intended to expand and / or cure in such ovens. Conventional processing of these high softening and high melting point materials into formulated foamable sealants requires high temperatures that can lead to premature activation and curing. The softening points of the polymers described herein can be measured according to ASTM-D1525.

[0028] The preferably high softening or melting point polymeric material may comprise about 30% or more, 40% or more, 50% or more, or 60% or more by weight of the total amount of polymeric material included in the foamable / curable sealant composition. The preferably high softening or melting point polymeric material may comprise about 30% or more, 40% or more, 50% or more, or 60% or more by weight of the total amount of polymeric material included in the foamable / curable sealant composition.

[0029] Preferably the high softening or melting point polymeric material is a thermoplastic material, preferably a polyolefin, more preferably an ethylene homopolymer or copolymer.

[0030] In a preferred embodiment, the polymeric material comprises or consists essentially of polyethylene.

[0031] In a preferred embodiment the polyethylene has a melt flow rate (MFR), measured according to ISO 1133 at 190°C and 2.16 kg, of at least 5 g / 10 min, preferably at least 10 g / 10 min, more preferably at least 20 g / 10 min, even more preferably at least 30 g / 10 min, even more preferably at least 40 g / 10 min, even more preferably at least 50 g / 10 min, most preferably at least 60 g / 10 min and especially at least 70 g / 10 min.

[0032] In a preferred embodiment the polyethylene has a melt flow rate (MFR), measured according to ISO 1133 at 190°C and 2.16 kg, of at most 70g / 10min, preferably at most 60g / 10min, more preferably at most 50g / 10min, even more preferably at most 40g / 10min, even more preferably at most 30g / 10min, even more preferably at most 20g / 10min, most preferably at most 10g / 10min and especially at most 5g / 10min.

[0033] As one non-limiting example, a preferably high softening or melting point polymeric material is a high density polyethylene (HDPE) resin.

[0034] As one non-limiting example, a preferably high softening or melting point polymeric material is a low density polyethylene (LDPE) resin.

[0035] As another non-limiting example, a preferably high softening or melting point polymeric material is a linear low density polyethylene (LLDPE) resin.

[0036] As another non-limiting example, the preferably high softening or melting point polymeric material is an ethylene copolymer with a low percentage of comonomer.

[0037] In a preferred embodiment, the polymeric material comprises or consists essentially of a copolymer, preferably an ethylene vinyl acetate copolymer.

[0038] In preferred embodiments, the copolymer, preferably an ethylene vinyl acetate copolymer, comprises at least about 1.0% by weight of the total polymeric material, preferably at least about 2.0% by weight, more preferably at least about 3.0% by weight, and even more preferably at least about 4.0% by weight.

[0039] In a preferred embodiment, the copolymer, preferably an ethylene vinyl acetate copolymer, comprises at least about 1.0 wt.%, preferably at least about 2.0 wt.%, more preferably at least about 3.0 wt.%, and even more preferably at least about 4.0 wt.% of the total volume-expandable sealant composition.

[0040] As noted above, the use of other polymeric materials is contemplated.

[0041] The one or more polymeric materials included in the foamable / curable sealant composition may be manufactured from a variety of raw materials. The one or more polymeric materials included in the foamable / curable sealant composition may be derived from recycled sources. For example, post-consumer source grades of polyethylene terephthalate are readily available from recycled water and soda bottles. High density polyethylene (HDPE) grades are readily available from recycled milk containers. Low density polyethylene (LDPE) and linear low density polyethylene (LLDPE) grades are readily available from many types of recycled films, including plastic shopping bags and injection molded bottle lids. Illustrative examples of foamable / curable sealant compositions containing recycled grades of low density polyethylene (LDPE) and linear low density polyethylene (LLDPE) are shown in Table 6, Examples I-18 and I-19.

[0042] The foamable / curable sealant composition may include one or more foaming agents. The one or more foaming agents may function to generate an inert gas that forms an open and / or closed cell structure within the foamable / curable sealant composition, as desired. The foamable / curable sealant composition may contain a physical or chemical foaming agent.

[0043] A physical blowing agent may consist of a low boiling point solvent encapsulated in a polymer shell, which upon heating softens the polymer shell and causes the low boiling point solvent to boil, expanding the polymer shell, increasing its volume and decreasing its density. One exemplary physical blowing agent suitable for use herein is available under the trade name EXPANCEL® commercially available from Nouryon, Inc.

[0044] Chemical blowing agents decompose upon exposure to heat, releasing a gas, causing a change in volume and a decrease in density of the polymeric composition they are incorporated in. Chemical blowing agents included in the foamable / curable sealant composition may be endothermic or exothermic.

[0045] Endothermic blowing agents are capable of absorbing heat from the matrix during activation. Suitable endothermic blowing agents include, but are not limited to, metal salts of carbonate and bicarbonate ions. Two exemplary endothermic blowing agents suitable for use herein are commercially available under the tradename KYCEROL™ from Rit-Chem and HYDROCEROL® from Clariant.

[0046] The exothermic blowing agent can release heat during activation. Suitable exothermic blowing agents include, but are not limited to, azodicarbonamide, dinitrosopentamethylenetetramine, p-toluenesulfonylhydrazide, or p,p'-oxybis(benzenesulfonylhydrazide). Preferably, azodicarbonamide is utilized as the exothermic blowing agent.

[0047] The blowing agent(s) may be present in an amount of 0.5% or less to about 11% or more by weight of the total foamable / curable sealant composition. The exact amount of blowing agent(s) may be selected based on the desired amount of volume change and the desired temperature of activation for a particular sealant application. As one non-limiting example, a low density polyethylene (LDPE) based composition containing 2% azodicarbonamide can achieve about a 200-300% increase in volume when heated at a temperature range of about 162.78-204.44°C (325-400°F) for about 20-40 minutes. Materials with this level of volume increase are preferred for applications such as water blocking and where some mechanical strength is required. Polyethylene-based compositions made according to the present teachings and in the range of about 200-400% expansion are suitable for sealing where some exposure to hydrocarbon fuels such as diesel fuel or gasoline is expected. Similarly, a low density polyethylene (LDPE) based sealant composition incorporating 4.2% azodicarbonamide blowing agent can achieve a 1000-1200% volume increase when heated for about 20-40 minutes at a temperature range of about 162.78-204.44°C (325-400°F). Incorporation of azodicarbonamide at a level of 8.4% produces a volume increase of as much as 2000%, as shown in illustrative Examples I-12 and I-13 of Table 3.

[0048] The foamable / curable sealant composition may include one or more blowing agent activators. The one or more blowing agent activators may function to lower the temperature at which the blowing agent produces gas to foam the composition. The one or more blowing agent activators lower the foaming temperature of the foamable / curable sealant composition, so their use requires further lowering of the compounding temperature before adding the blowing agent and the associated blowing agent activator. The one or more blowing agent activators may include zinc or calcium salts, and / or nitrogen-containing compounds. Preferably, the blowing agent activator is a metal salt or oxide, e.g., a metal oxide such as zinc oxide. Other preferred blowing agent activators include ureas and substituted ureas. Dicyandiamide may also be used as a blowing agent activator.

[0049] The foamable / curable sealant composition may include one or more components that function to either lower the melting temperature or softening point, to lower the viscosity, or to lower both the melting temperature or softening point and the viscosity of the foamable / curable sealant material. The one or more components for lowering the melting temperature, softening point and / or viscosity, defined herein as temperature processing aids, are preferably fully compatible or at least partially compatible with the other polymeric components of the foamable / curable sealant composition in the solid phase, the melt phase, or both. The one or more temperature processing aids are preferably added to the foamable / curable sealant composition in the early stages of processing to reduce the temperature and shear heating that occurs in subsequent processing stages where heat sensitive components may be added. The one or more temperature processing aids include, but are not limited to, hydrocarbon resins, process oils, liquid elastomers, waxes or low molecular weight polymers and copolymers. The total of the one or more temperature processing aids is preferably present in an amount of about 10% or more, more preferably 20% or more, and even more preferably 30% or more. The total of the one or more temperature processing aids is preferably present in an amount of about 50% or less. The one or more temperature processing aids may include hydrocarbon resins, waxes, liquid elastomers, and low molecular weight polymers.

[0050] The one or more temperature processing aids may include one or more hydrocarbon resins. The one or more hydrocarbon resins may function to reduce the melting temperature or softening point of the foamable / curable sealant composition. The one or more hydrocarbon resins may function to reduce the melt viscosity of the foamable / curable sealant composition. The one or more hydrocarbon resins may function to improve the adhesion of the foamable / curable sealant composition to a substrate (e.g., metal). Additionally, the one or more hydrocarbon resins may function to improve the overall corrosion resistance. The hydrocarbon resins may be present in an amount of about 5% or less to about 15% or more of the total weight of the foamable / curable sealant composition. Suitable hydrocarbon resins may include, but are not limited to, aromatic C-9 resins, aliphatic C-5 resins, and / or combinations thereof, as shown in the exemplary Tables 1 and 2 presented herein. Suitable hydrocarbon resins may also include coumarone-indene resins and those based on farnesene. Suitable hydrocarbon resins may also include rosin acids and esters derived from biosources.

[0051] In a preferred embodiment, the one or more hydrocarbon resins comprise at least about 1.0 wt.%, preferably at least about 2.0 wt.%, more preferably at least about 3.0 wt.%, and even more preferably at least about 4.0 wt.% of the total volume-expandable sealant composition.

[0052] In a preferred embodiment, the one or more hydrocarbon resins comprise at most about 10% by weight of the total volume-expandable sealant composition, preferably at most about 9.0% by weight, more preferably at most about 8.0% by weight, and even more preferably at most about 7.0% by weight.

[0053] The foamable / curable sealant composition may also lack one or more hydrocarbon resins. As can be seen from Comparative Example C2 in Table 2 (prepared without any hydrocarbon resin), the expansion results show that the inclusion of a hydrocarbon resin in the foamable / curable sealant composition is not essential to obtain good expansion properties. Thus, the composition without a hydrocarbon resin may be suitable for various applications known to those skilled in the art. However, the incorporation of an appropriate amount of one or more hydrocarbon resins may prove beneficial to obtain one or more of the improvements listed herein, such as ease of processing, improved adhesion to metals, and / or improved corrosion resistance.

[0054] The foamable / curable sealant composition may include a process oil. The process oil may function to lower the melting point or softening point of the base polymer. The process oil may function to lower the viscosity of the foamable / curable sealant composition. Additionally, the process oil may function to lower the overall cost of the foamable / curable sealant composition. The process oil may be present in an amount of about 5% or less to about 15% or more of the total weight of the foamable / curable sealant composition. A suitable process oil may be paraffin oil or any other known process oil in the art and literature suitable for use herein. It is also contemplated that the foamable / curable sealant composition may lack a process oil.

[0055] Waxes are low molecular weight solids that are oleophilic and hard, but malleable. These can include paraffin waxes, as well as vegetable- and animal-based waxes. Liquid elastomers include, but are not limited to, polyisobutylene, polybutadiene (available under the trade name Indopol® from INEOS), isoprene rubber, styrene butadiene rubber, ethylene propylene rubber (EPR) and ethylene propylene diene monomer (EPDM) rubber (available under the trade name Trilene® from Lion Elastomers). Low molecular weight copolymers suitable for reducing melting point and / or viscosity include, but are not limited to, polyolefin elastomers and plastomers (e.g., ethylene octene copolymers available under the trade name Affinity® GA series available from Dow, with a melt index of 500-1500 g / 10 min, 2.16 Kg at 190°C). Also suitable are ethylene methacrylate, ethylene butyl acrylate and ethylene vinyl acetate copolymers, especially those having higher melt flow rates and / or lower melting points than the polymers they modify.

[0056] The foamable / curable sealant composition may include one or more coagents. The one or more coagents may function to improve the crosslinking of the foamable / curable sealant composition. The one or more coagents may function to improve the entrapment of gas. Typically, the coagent may be a low molecular weight monomeric or oligomeric material having reactive double bonds that react by a free radial mechanism. The one or more coagents may be maleimide-based or may contain allyl, vinyl, acrylate, or methacrylate functionality. A common factor for the coagent is the presence of a free radical curable double bond that functions to react with the free radical generator and the polymeric material of the foamable / curable sealant composition. The one or more coagents may be monofunctional, difunctional, or polyfunctional, which refers to the number of double bonds in each molecule of the coagent. Suitable coagents may include, but are not limited to, phenylmethane maleimide formaldehyde condensates, aliphatic bismaleimides, aromatic bismaleimides, ethoxylated bisphenol A diacrylate, trimetholyl propane trimethactrylate, dipentaerythritol pentaacrylate, hexaacrylate blends, and / or combinations thereof. Preferred coagents are based on maleimide functionality because of their ability to work well at very low concentrations, i.e., as low as 0.2% by weight of the total formulation. It is contemplated that the foamable / curable sealant composition may lack one or more coagents. However, the illustrative examples in Table 1 show the beneficial effect of increased expansion at all bake conditions, especially at the high bake temperature of 400°F, compared to Comparative Example C-1, which does not contain a coagent.

[0057] The foamable / curable sealant composition may include one or more free radical generators. Free radical generators in which the generation of free radicals is initiated or accelerated by an external stimulus such as heat or ultraviolet radiation are preferred. In a preferred embodiment, the generation of free radicals is accelerated by heat. Free radical generators include, but are not limited to, persulfates, azo compounds, and hydroperoxides. In a preferred embodiment, the free radical generator is an organic peroxide. The one or more free radical generators can function to generate a sufficient amount of free radicals to affect crosslinking of the foamable / curable sealant composition by interacting with one or more coagents and one or more polymeric materials contained in the composition. The one or more free radical generators used in the final stage of formulation may have a long half-life at ambient and slightly elevated temperatures. The one or more organic peroxides may exhibit a shorter half-life at temperatures near or above the temperature at which the composition is formulated to generate gas. The one or more free radical generators may be present in an amount of about 0.5% or less to about 1.5% or more of the total weight of the foamable / curable sealant composition. Suitable free radical generators of the organic peroxide type include, but are not limited to, butyl 4,4-di(tert-butylperoxy)-valerate, and 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, or any other known organic peroxides in the art and literature suitable for use herein.

[0058] Comparative Example C-3, shown in Table 2, is formulated without any organic peroxide. The expansion at lower bake conditions is similar to that with organic peroxide, but the composition has improved flowability since the vertical rise of the composition is lower. More importantly, the volume expansion at high temperatures of about 400°F is significantly reduced without the addition of organic peroxide. Thus, the addition of organic peroxide proves beneficial in increasing the volume expansion at high bake temperatures.

[0059] The foamable / curable sealant composition may include an antioxidant. The antioxidant may function to prevent degradation of the polymeric material during formulation and / or to scavenge free radicals that may be generated during formulation of the foamable / curable sealant composition. The antioxidant may be already incorporated into the polymeric material of the foamable / curable sealant composition by the manufacturer or may be added separately to the foamable / curable sealant composition. A suitable antioxidant may be any suitable antioxidant known in the art and literature. The antioxidant levels suitable for use herein may be those present and added to the polymeric material by the manufacturer. It is also contemplated that the foamable / curable sealant composition may lack an antioxidant.

[0060] The foamable / curable sealant composition may include one or more pigments. The one or more pigments may be useful for marking the foamable / curable sealant composition to identify and / or detect the sealant and ensure proper installation of the seal during assembly operations. Suitable pigments may include, but are not limited to, various organic and inorganic pigments, metal oxides, carbon black, and the like.

[0061] The foamable / curable sealant composition may include one or more inert fillers. The one or more inert fillers may function to reinforce cell walls to improve foaming properties. The one or more inert fillers may function to change the rheology of the foamable / curable sealant composition to reduce sagging or slippage of the sealant before or during curing, especially when the composition is heated. Additionally, the inert fillers may function to lower the overall cost of the foamable / curable sealant composition. Suitable inert fillers may include, but are not limited to, calcium carbonate, talc, wollastonite, various types of clay, metal oxides, silica, mica, and the like. The one or more inert fillers may include materials in the form of fibers, such as glass fibers, aramid fibers, cellulose fibers, polymeric fibers, and the like. The one or more inert fillers may be present as round or substantially round particles and / or as flakes, needles, and platelets. It is also contemplated that the foamable / curable sealant composition may be devoid of inert fillers.

[0062] formation The formation of the foamable / curable sealant composition may be accomplished by a multi-stage or multi-step processing method. In a first blending step, the polymeric material is blended with the modifying component. The polymeric material may exhibit a high melting point or a high softening point, as described herein above. The modifying component may function to lower the melting or softening point, to lower the viscosity, or to lower both the melting or softening point and the viscosity of the polymeric material. The modifying component may be selected from low melting or softening point polymeric materials, low molecular weight polymeric materials, waxes, hydrocarbon resins, plasticizers, process oils, or combinations thereof, as described herein. Preferably, the modifying component is added at a lower level than the high melting or softening point polymeric material. Preferably, the modifying component is at least partially compatible with the high melting or softening point polymeric material. It is contemplated that blending of the high melting or softening point polymeric material with the modifying component may be performed in one or more initial first steps, as needed, to obtain the desired resulting first mixture. The resulting first mixture may include a mixture having a low melting or softening point, low viscosity, or both. Importantly, ingredients that play a role in the activation of the foamable / curable sealant composition are not included in these first compounding steps.

[0063] For safe compounding (i.e., to avoid undesired activation during part formation), compounding temperatures may need to be kept well below the temperature at which the foamable / curable sealant composition activates. For effective mixing, it may be necessary to compound the polymeric materials at temperatures above their softening or melting points. For example, for crystalline polymeric materials, compounding temperatures are preferably at least 10°C higher than the melting temperature of the material. For amorphous polymeric materials that do not have a distinct melting temperature, it may be necessary to compound the materials at temperatures at least 10°C higher than their softening points. Preferably, compounding may be performed at temperatures at least 20°C higher than the softening point of the material. For materials according to the teachings herein that foam and / or cure at about 150°C or lower, it may be necessary to compound such materials at about 120°C or lower, or preferably about 110°C or lower, or more preferably 105°C or lower. Thus, when using a single-step or single-stage process, the polymeric materials that can be used may be limited to those with melting or softening points below 100°C. Some exemplary polymeric materials of this type include, but are not limited to, copolymers of ethylene monomers, such as vinyl acetate, methyl acrylate, ethyl acrylate, and butyl acrylate, at comonomer levels of 18% or more. Such materials are effective in destroying the regularity of the polymer chain and thus destroying its ability to crystallize. Additionally, suitable exemplary elastomeric materials that do not have a discernible melting or softening point include, but are not limited to, ethylene propylene diene monomer rubber (EPDM), styrene-butadiene rubber (SBR), nitrile butadiene rubber (NBR), and bromobutyl rubber.

[0064] In a second or subsequent compounding step, the resulting mixture is compounded with one or more foamable / curable components. The foamable / curable components may be selected from blowing agents, blowing agent activators, coagents, and the like, or combinations thereof, as described herein. This second or subsequent compounding step is performed at a lower temperature than the first compounding step, and is typically or preferably of shorter duration than the first compounding step. Importantly, this second or subsequent compounding step is not performed until the processing temperature of the mixture has been reduced, so as not to activate heat sensitive components.

[0065] In some cases, masterbatches may be generated during the multi-step processing method. When a portion of the final product is compounded and collected for further processing, the material is typically referred to as a masterbatch. However, it is not necessary to generate and separate a masterbatch. For example, if both the first compounding step and the second or subsequent compounding steps are performed using a batch mixing process, it is not necessary to discharge the product mixture of the first compounding step from the mixer or to cool it to ambient temperature. Instead, it is necessary to remove enough heat energy from the first product mixture so that activation of the reactive components added during the second or subsequent compounding steps does not occur.

[0066] The illustrative examples in Table 5 were prepared without the use of a masterbatch to demonstrate that the foamable / curable sealant compositions of the present teachings can instead be prepared according to the careful stepwise addition of the components. Whether or not the formation of a separate masterbatch is used, it is important that the temperature of the combined components be low enough so as not to activate the foaming agent or crosslinking agent used to produce the final foamable composition.

[0067] Mixing and molding In the multi-step processing method presented herein, various types of mixing techniques can be employed. It is contemplated that the foamable / curable sealant composition can be prepared using any suitable mixing technique known in the art and literature, provided that the first compounding step produces a mixture suitable for use in the second or subsequent compounding steps. For example, batch compounding, continuous compounding, or a combination thereof may be employed. Batch mixing equipment suitable for use herein includes, but is not limited to, double arm sigma blade mixer, Banbury mixer, Shaw mixer, planetary mixer, and the like. Continuous processing equipment suitable for use herein includes, but is not limited to, co-rotating or counter-rotating twin screw extruder, Buss kneader, single screw extruder with mixing elements, and the like.

[0068] In a conventional one-step batch compounding process, all components requiring melt processing must be melt processable at temperatures below the activation temperature of the heat-reactive components. Melt processing of crystalline materials must occur at temperatures at least slightly above their melting points (e.g., above 10°C). Melt processing of amorphous materials must occur at temperatures at least slightly above their softening points. Melt processable components include thermoplastic polymers, rubbers or elastomers, solid hydrocarbon resins, solid epoxy resins, and the like. In a one-step compounding process, the minimum processing temperature is determined by the component with the highest melting or softening point. To avoid the possibility of activation of heat-activated components, the maximum processing temperature will be at least 10°C lower, more preferably 20°C lower, and more preferably 30°C lower than the activation temperatures of heat-activated components (e.g., blowing agents and latent peroxides).

[0069] The foamable / curable sealant composition / material formed by the multi-step processing method may be shaped according to various techniques known in the art and literature. For example, the foamable / curable sealant material may be preformed. Preformed is defined herein as being delivered with a well-defined shape and stable dimensions prior to activation. The material may be delivered as sheets, strips, patches, rings, disks, and the like. In one embodiment, the foamable / curable sealant material may be injection molded. In another embodiment, the foamable / curable sealant material may be extruded (e.g., in sheets) or through a profile die that produces a continuous flow of material with complex geometric shapes. The material can then be cut into sections of desired length to create three-dimensionally shaped parts. The material may be delivered alone or in combination with other components such as metals, composites, thermosets, thermoplastics, and the like. In a preferred embodiment, the material is delivered to a molded polyamide or polyester to form a sealing baffle.

[0070] The term baffle is defined herein to mean a structure designed to form a barrier against the movement of air, moisture, dust, noise, combinations thereof, and the like. A typical design combines an inert component, such as a thermoplastic, thermoset, metal, composite, or the like, with a foamable / curable material that foams and adheres to various surfaces. The foamable / curable material may be disposed around the inert material. The baffle may include pins or tabs for positioning the baffle prior to activation of the foamable / curable material, and for installation of the baffle. When inserted into a cavity, for example, in an A-pillar, B-pillar, or C-pillar of an automobile, there is a space between the baffle and the wall of the cavity that the baffle is intended to seal, thereby allowing various cleaning solutions, phosphating solutions, and electrocoat solutions to escape from the vehicle. However, upon activation, the sealant material disposed around the baffle foams until it contacts and adheres to the cavity wall, thus sealing the cavity and firmly installing the baffle. [Example]

[0071] The present teachings can be further illustrated by the following non-limiting examples presented in tabular form. The components used in the illustrative examples and comparative controls are listed in Table 7 below. Additionally, Table 6 presented herein below shows the masterbatch compositions used in the illustrative examples.

[0072] Illustrative Examples I-1 through I-7 and Comparative Control C-1 are shown in Table 1. Comparative Control C-1 was prepared without the use of any co-agents.

[0073] [Table 1]

[0074] Table 2 shows illustrative examples I-8 to I-11 and comparative examples C2 and C3. Comparative example C2 was prepared without the use of a hydrocarbon resin. Comparative example C3 was prepared without the use of an organic peroxide.

[0075] [Table 2]

[0076] Table 3 shows the larger volume expansion of illustrative examples I-12 and I-13.

[0077] [Table 3]

[0078] Table 4 shows illustrative examples I-14 to I-17.

[0079] [Table 4]

[0080] Table 5 shows the use of recycled polyethylene in illustrative examples I-18 and I-19. The components used in the illustrative examples are listed in Table 7 below.

[0081] [Table 5]

[0082] Table 6 shows the masterbatch compositions A through E used in the illustrative examples.

[0083] [Table 6]

[0084] Table 7 lists the ingredients used in the illustrative examples and comparative examples.

[0085] [Table 7]

[0086] The data in Tables 8 to 10 show several positive performance advantages associated with the compositions of the above inventive examples. The data in Table 8 demonstrate that the compositions of the teachings herein can maintain very good foaming performance at the indicated bake conditions, even after exposure to severe humidity at 35° C. for one week immediately prior to activation. The materials maintain over 85% of their volumetric expansion after this humidity exposure condition, when compared to the volumetric expansion without such exposure. The improved foaming behavior after exposure to humidity is especially evident at higher bake temperature conditions. The materials according to the invention also advantageously have fewer surface defects and better cell structure when activated after humidity exposure, compared to commercial sealants with similar expansion. The resulting L-2811 commercial sealant after exposure is shown in FIG. 1, and Examples I-2 and I-5 are shown in FIG. 2A and FIG. 2B. In each figure, the sample on the left was exposed to a temperature of 400°F for 40 minutes, the sample in the middle was exposed to a temperature of 340°F for 20 minutes, and the sample on the right was exposed to a temperature of 325°F for 30 minutes.

[0087] [Table 8]

[0088] Materials according to the teachings herein also demonstrate performance advantages after activation. The data in Table 9 demonstrate that materials according to the teachings herein have lower water absorption after activation compared to commercially available materials with similar volume expansion levels.

[0089] [Table 9]

[0090] The data in Table 10 demonstrate that materials according to the teachings herein can also achieve improved resistance to exposure to hydrophobic fluids such as automotive fuel. The durometer of several inventive materials and commercial controls is measured after activation, followed by 24 hours of immersion in Ford Fuel B, a mixture of 70% by weight isooctane and 30% by weight toluene. Immediately after the 24 hours of exposure, the durometer of each material is remeasured. The materials according to the teachings herein retain at least half of their initial durometer reading after 24 hours of immersion in Fuel B, while the durometer reading of the commercial high expansion material drops to 0. Even the higher expansion examples I-12 and I-13 retain more than 50% of their initial durometer value.

[0091] [Table 10]

[0092] Unless otherwise specified, all ranges include both the endpoints and all numbers between the endpoints. The use of "about" or "approximately" in connection with a range applies to both ends of the range. Thus, "about 20 to 30" is intended to encompass "about 20 to about 30," including at least the specified endpoints.

[0093] The term "generally" or "substantially" to describe an angle measurement may mean about + / -10° or less, about + / -5° or less, or even about + / -1° or less. The term "generally" or "substantially" to describe an angle measurement may mean about + / -0.01° or more, about + / -0.1° or more, or even about + / -0.5° or more. The term "generally" or "substantially" to describe a length measurement, percentage, or ratio may mean about + / -10% or less, about + / -5% or less, or even about + / -1% or less. The term "generally" or "substantially" to describe a length measurement, percentage, or ratio may mean about + / -0.01% or more, about + / -0.1% or more, or even about + / -0.5% or more.

[0094] Unless otherwise specified, any numerical value described herein includes all values ​​from the lower limit to the upper limit in increments of one unit, provided that there is an interval of at least two units between any lower limit and any upper limit. As an example, if the amount of an ingredient, property, or value of a process variable, such as temperature, pressure, time, etc., is, for example, from 1 to 90, 20 to 80, or 30 to 70, the intermediate range values ​​(e.g., 15 to 85, 22 to 68, 43 to 51, 30 to 32, etc.) are intended to be within the scope of the teachings of this specification. Similarly, individual intermediate values ​​are also within the scope of the teachings. For values ​​less than one, one unit is considered to be 0.0001, 0.001, 0.01, or 0.1, as appropriate. These are merely examples of what is specifically intended, and all possible combinations of numerical values ​​between the lowest and highest values ​​recited should be considered to be expressly set forth in this application in a similar manner. Unless otherwise stated, all ranges include both the endpoints and all numbers between the endpoints.

[0095] As will be apparent, any teaching herein of an amount expressed as "parts by weight" also contemplates a similar range expressed as weight percent. Thus, expression of a range as "at least 'x' parts by weight of the product composition" also contemplates the teaching of an amount range of "'x' weight percent" of the product composition, which is similarly described.

[0096] The term "consisting essentially of" to describe a combination is intended to include the specified elements, ingredients, components, or steps, as well as other such elements, ingredients, components, or steps that do not materially affect the basic and novel characteristics of the combination. The use of the terms "comprising" or "including" to describe combinations of elements, ingredients, components, or steps herein also contemplates embodiments that consist essentially of the elements, ingredients, components, or steps.

[0097] Multiple elements, components, ingredients, or steps may be provided by a single integrated element, component, ingredient, or step. Alternatively, a single integrated element, component, ingredient, or step may be divided into separate multiple elements, components, ingredients, or steps. The disclosure of "a" or "one" to describe an element, component, ingredient, or step is not intended to exclude additional elements, components, ingredients, or steps.

[0098] It is understood that the above description is intended to be illustrative, and not limiting. Many embodiments of the means, as well as many applications other than the examples provided, will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the invention should not be determined with reference to the above description, but rather with reference to the appended claims, along with the full scope of equivalents to which the claims are entitled. The disclosures of all articles and references, including patent applications and publications, are incorporated by reference for all purposes. Omission in the following claims of any aspect of the inventive subject matter disclosed herein should not be construed as a disclaimer of such subject matter, nor as a disapproval of such subject matter by the inventors that they did not consider such subject matter to be part of the disclosed inventive subject matter.

Claims

1. In the sealant composition, i. one or more polymeric materials, preferably with a high softening or melting point; ii. one or more blowing agents; iii. one or more blowing agent activators; iv. one or more thermal processing aids; A sealant composition comprising: the one or more processing aids are selected from hydrocarbon resins, waxes, liquid elastomers, low molecular weight polymers, and combinations thereof; Sealant composition.

2. The sealant composition of claim 1 including a coagent selected from an acrylate, a methacrylate, or a maleimide.

3. 3. The sealant composition of claim 1 or 2, wherein the one or more, preferably high softening or melting point, polymeric materials are selected from high density polyethylene (HDPE), low density polyethylene (LDPE), or linear low density polyethylene (LLDPE).

4. 3. The sealant composition of claim 1 or 2, wherein the one or more, preferably high softening or melting point, polymeric materials are recycled from post-industrial or post-consumer sources.

5. 3. The sealant composition of claim 1 or 2, wherein the one or more, preferably high softening or melting point, polymeric materials comprise at least about 50% or more of the total composition of the activatable sealant.

6. 3. The sealant composition of claim 1 or 2, wherein the one or more blowing agents is azodicarbonamide.

7. 3. The sealant composition of claim 1 or 2, wherein the one or more blowing agent activators are selected from zinc oxide, dicyandiamide, calcium salts, ureas, or substituted ureas.

8. The sealant composition of claim 1 or 2, which is heat activated.

9. 3. The sealant composition of claim 1 or 2, supplied to an article of manufacture as a sheet, strip, patch, ring, disc, or combination thereof.

10. 3. The sealant composition of claim 1 or 2, wherein the article of manufacture is a sealing baffle for an automotive vehicle.

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