Different-phase thermoplastic composition for use as a sound insulation material with improved damping performance

Abstract

The heterophase thermoplastic composition comprises a polyolefin continuous phase containing an ethylene / α-olefin interpolymer and an acrylic discontinuous phase dispersed in the polyolefin continuous phase at a rate of less than 20 pphr per 100 parts per resin, wherein the composition has a tanδ of 0.11 or greater at a frequency of 200 rad / s. A method that may include preparing the heterophase thermoplastic composition comprises combining a polyolefin and an acrylic resin to form a blend, and heating the blend to form a polyolefin continuous phase in which the acrylic discontinuous phase is dispersed.

Description

[Technical Field]

[0001] This invention relates to heterogeneous olefin acrylate hybrid materials for use in sound insulation and attenuation applications. [Background technology]

[0002] Plastics and other products used in sound insulation materials form an important part of soundproofing in residential, automotive, and commercial environments. Sound insulation materials are usually made into extruded and thermoformed sheets that are trimmed and installed to improve sound attenuation of internal and / or external noise sources. Alternatively, some materials are injection molded to take the shape of the area to minimize the trimming operation. Many solutions have been proposed to reduce noise and vibration in different parts of a vehicle; for example, the use of dash mats and flooring carpets in the vehicle cabin is a known method to minimize noise problems.

[0003] Among plastics, sound-insulating materials containing polyolefin resins are thermoformable, mechanically strong, and offer improved sound attenuation. Non-polar polyolefin materials are often preferred over other plastics (e.g., PVC or EVA) due to the need to reduce VOC emissions and associated odors. Generally, increasing the density and attenuation (i.e., tanδ) of a sound-insulating material results in improved observed sound attenuation properties. Conventional approaches to achieve this have involved adding inorganic fillers to increase density and corresponding sound-insulating properties. However, increased density is accompanied by decreased flexibility and elongation properties, potentially resulting in compositions that are too rigid and brittle for installation and handling in many intended applications. [Overview of the project]

[0004] In one embodiment, the present disclosure relates to a heterophase thermoplastic composition comprising a polyolefin continuous phase containing an ethylene / α-olefin interpolymer and an acrylic discontinuous phase dispersed in the polyolefin continuous phase at a rate of less than 20 pphr per 100 parts per resin, and having a tanδ of 0.11 or more at a frequency of 200 rad / s.

[0005] In another embodiment, the present disclosure relates to a method which may include preparing a heterogeneous thermoplastic composition, comprising combining a polyolefin and an acrylic resin to form a blend, and heating the blend to form a continuous polyolefin phase in which an acrylic discontinuous phase is dispersed. [Modes for carrying out the invention]

[0006] Each embodiment relates to heterogeneous thermoplastic composite compositions having a polyolefin matrix phase and a discontinuous acrylic polymer internal phase, suitable for a wide range of sound insulation and attenuation applications. The heterogeneous thermoplastic composite compositions may have a density of at least 1.5 g / cc, and the compositions have a tanδ of 0.11 or greater at a frequency of 200 rad / s. The method involves blending the polyolefin matrix phase with an acrylic polymer and optionally a filler to produce a dispersed acrylic discontinuous phase.

[0007] The heterophase materials disclosed herein are multiphase materials that incorporate a polyolefin continuous phase forming a matrix to a dispersed acrylic discontinuous phase that enhances sound insulation properties, while minimizing changes in the mechanical properties of the matrix phase. Specifically, by maintaining the proportion of the acrylic discontinuous phase in the heterophase thermoplastic composition below a "penetration threshold" of 20 parts per 100 parts of resin (pphr), the acrylic internal phase is kept discontinuous and does not form a mutually penetrating network. Maintaining the discontinuous acrylic internal phase provides a material with improved sound attenuation performance while minimizing negative effects on the tensile properties of the blend and copolymer materials that form a mutually penetrating network. Generally, the heterophase thermoplastic compositions disclosed herein may have a density of at least 1.5 g / cc, a tensile strength of 1.5 MPa or higher, and a tensile elongation at break of 30% or higher. Sound insulation materials made from heterophase materials exhibit flexibility (e.g., low Shore A) and may be suitable for assembly in many applications, including automotive, industrial, and construction.

[0008] Heterogeneous thermoplastic compositions include a polyolefin phase that can form a continuous matrix supporting an acrylic discontinuous phase, thereby increasing mechanical durability and tensile elongation. The combination of the polyolefin phase and the acrylic phase is defined as the polymer or "resin" portion of the heterogeneous thermoplastic composition. Examples of polyolefins include homopolymers, random and block interpolymers, and random and block copolymers prepared from C2-C10 linear, branched, or cyclic α-olefins. Preferred polyolefins include ethylene / α-olefin interpolymers and copolymers and propylene / α-olefin interpolymers and copolymers. Examples of α-olefins, but not limited to these, include C3-C20 linear, branched, or cyclic α-olefins, such as propene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-octadecene. α-olefins may also have cyclic structures such as cyclohexane or cyclopentane, resulting in α-olefins such as 3-cyclohexyl-1-propene (allylcyclohexane) and vinylcyclohexane; norbornene and related olefins; and α-methylstyrene. Non-limiting examples of such ethylene / α-olefin copolymers and interpolymers include nearly linear, uniformly branched olefin interpolymers such as AFFINITY® Polyolefin Plastomer and ENGAGE® Polyolefin Elastomer, available from The Dow Chemical Company.

[0009] The heterogeneous thermoplastic composition may contain a continuous polyolefin phase having a density according to ASTM D3574-17 of 0.95 g / cc or less, 0.92 g / cc or less, 0.90 g / cc or less, or in the range of 0.85 g / cc to 0.95 g / cc. In some cases, the continuous polyolefin phase has a melt index according to ASTM D1238-20 in the range of 0.8 to 10 g / 10 min (2.16 kg at 190°C).

[0010] The heterogeneous thermoplastic composition may contain a polyolefin continuous phase in the range of 5% to 30% by weight, 10% to 30% by weight, or 10% to 25% by weight, in weight percent (wt%).

[0011] The polyolefin continuous phase may contain secondary polyolefins such as high-density polyethylene (HDPE) to adjust rigidity and improve high-temperature performance. The polyolefin continuous phase may contain a constant fraction of HDPE having a density according to ASTM D3574-17 of 0.99 g / cc or less, or 0.98 g / cc or less, or in the range of 0.93 g / cc to 0.97 g / cc.

[0012] In some cases, the heterogeneous thermoplastic composition may contain high-density polyethylene as a component of the polyolefin continuous phase in an amount of 10% by weight or less, 8% by weight or less, 6% by weight or less, or in the range of 0.1% by weight to 10% by weight.

[0013] HDPE may have a melt index according to ASTM D1238-20 in the range of 0.5 to 10 g / 10 min (2.16 kg at 190°C).

[0014] Heterogeneous thermoplastic compositions may include an acrylic internal phase that forms a discontinuous distribution of acrylic particles within a polyolefin continuous phase. The acrylic discontinuous phase is added at a concentration below the penetration threshold to minimize the formation of co-continuous phase morphology (i.e., interpenetration networks). While not limited to theory, the formation of co-continuous morphology can result in a decrease in tensile elongation and other mechanical properties.

[0015] The acrylic discontinuous layer can be prepared from one or more alkyl (meth)acrylate monomers. As used herein, "(meth)acrylic" refers to both the acrylate monomer and the methacrylate monomer. The acrylic internal phase can be prepared from at least one of acrylic polymers or copolymers. In some cases, the acrylic internal phase may be non-crosslinked and / or contain linear (meth)acrylate polymers. The acrylic internal phase may contain one or more alkyl (meth)acrylate monomers, including derivatives of (meth)acrylate monomers having alkyl chains in the range of 1 to 20 carbon atoms, such as ethyl (meth)acrylate, ethylhexyl (meth)acrylate, methyl (meth)acrylate, butyl (meth)acrylate, lauryl (meth)acrylate, and poly(ethylene glycol) methacrylate.

[0016] The acrylic internal phase may contain a mixture of at least one alkyl (meth)acrylate and one or more comonomers, such as one or more further non-alkyl acrylate comonomers. Suitable non-alkyl acrylate comonomers include acrylic acid, ethylenically unsaturated aromatic monomers including styrene, alkylstyrenes (e.g., methylstyrene and ethylstyrene), and acrylamide monomers (e.g., dimethylacrylamide and diacetoneacrylamide). One or more non-alkyl acrylate comonomers may be present in the acrylic internal phase in weight percent (W%) up to 60%, 50%, or 40%, or in the range of 0% to 50%.

[0017] In some cases, the acrylic internal phase may contain a resin having, as a weight percentage, 50% to 80% by weight of alkyl (meth)acrylate, 0% to 30% by weight of styrene, and 0% to 10% by weight of acrylic acid.

[0018] The heterogeneous thermoplastic composition may contain an acrylic internal phase having a density according to ASTM D3574-17 of 0.95 g / cc or less, 0.92 g / cc or less, 0.90 g / cc or less, or in the range of 0.85 g / cc to 0.95 g / cc.

[0019] The acrylic internal phase may have a glass transition temperature (Tg) in the range of -60°C to 10°C or -40°C to -10°C, calculated by Fox's formula, and may contain a non-crosslinked component, which has a calculated Tg of less than -10°C (or is completely non-crosslinked). g This is calculated using Fox's formula [Bulletin of the American Physical Society 1,3 Page 123 (1956)]. Fox's formula is as follows: T g Calculate:

[0020]

number

[0021] In Fox's formula, w1 and w2 refer to the weight fractions of two comonomers based on the weight of the monomer packed into the reactor, T g(1) and T g(2) This refers to the glass transition temperature of two corresponding homopolymers at Kelvin temperature. If three or more monomers are present, an additional term (w) is used. n / T g(n) ) is added. For the purposes of this disclosure, the glass transition temperatures of homopolymers are those reported in the “Polymer Handbook” edited by J. Brandrup and E. Himmergut, Interscience Publishers, 1966. If the publication does not report the Tg of a particular homopolymer, the Tg of the homopolymer is measured by differential scanning calorimetry (DSC).

[0022] The heterophasic thermoplastic composition may contain an acrylic discontinuous phase in the range of 20 parts per hundred resin (pphr) or less, 15 pphr or less, or 10 pphr or less, or 5 pphr to 18 pphr.

[0023] The heterophasic thermoplastic composition may contain one or more fillers including calcium carbonate, barium sulfate, silica, alumina, alumina trihydrate (ATH), wollastonite, clay (e.g., kaolin), mica, talc, fibers, particles, or beads of reinforcing materials (e.g., glass, carbon fiber, graphite, graphene, etc.), derivatives of any of them, and the like. The one or more fillers can be added in the range of 0 weight % to 85 weight %, or 0 weight % to 80 weight %, or 1 weight % to 80 weight % in terms of weight percentage (wt%) of the composition. The particle sizes of the fillers can be different, but can have an average particle size (d50) in the range of 1 micron to 30 microns.

[0024] The heterophasic thermoplastic composition can also contain one or more dispersants that promote the dispersion, distribution, and wetting of the filler additives. Suitable dispersants include C6 - C25 linear, branched, cyclic, or aromatic fatty acids, such as myristic acid, stearic acid, palmitic acid, behenic acid, oleic acid, tall oil, tall oil fatty acid, alkenyl succinic anhydride, monoesterified alkenyl succinic anhydride, and the like. The concentration of the dispersant added should be sufficient to promote the dispersion of the filler but can be below the threshold that affects the thermoforming performance or causes excessive odor. In some cases, the dispersant can be added to the heterophasic thermoplastic composition in the range of up to 2 weight %, or up to 1 weight %, or 0.1 weight % to 2 weight % in terms of weight percentage (wt%).

[0025] The heterophasic thermoplastic composition may contain a resin extender such as process oil or mineral oil at up to 10 weight %, 8 weight %, or 5 weight % in terms of weight percentage.

[0026] The heterogeneous thermoplastic composition may contain one or more additives, including defoaming agents; colorants such as colorants, dyes or pigments; film-forming agents, thickeners, moisture-scavenging agents (e.g., zeolites, molecular sieves, p-toluenesulfonyl isocyanates, etc.), odor absorbers (e.g., activated carbon, zeolites, etc.), adhesion promoters, thixotropic agents, antioxidants; wetting agents such as surfactants; filler dispersants, thickeners, compatibilizers, settling inhibitors, syneresis inhibitors, flame retardants, and / or filler treatment agents.

[0027] The heterogeneous thermoplastic composition may have a Shore A hardness of less than 100, less than 90, or less than 80 according to ASTM D2240 at a holding time of 10 seconds.

[0028] The heterogeneous thermoplastic composition may have a tensile elongation at break according to ATMM D412 type C at 25°C, characterized by elongations of more than 20%, more than 30%, or more than 40%.

[0029] The heterogeneous thermoplastic composition may have a density of at least 1.2 g / cc, 1.5 g / cc, or 1.7 g / cc according to ASTM D792-16.

[0030] The heterogeneous thermoplastic composition may have a tanδ of 0.05 or higher, 0.10 or higher, 0.11 or higher, 0.14 or higher, or 0.15 or higher, or in the range of 0.05 to 0.5 at 200 rad / s.

[0031] The bar torsion mode can be used to characterize the shear storage modulus, loss modulus, and tanδ. The bar torsion mode can be performed on a sample approximately 3 mm thick using a torsion test fixture with ARES-G2 (TA Instruments). For the test, a sample strip 12.75 mm wide and 40 mm long is punched out from the plaque and fixed with a clamp. Frequency sweeps are performed in 10°C increments with 10 minutes of equilibration, capturing data in the range of -30 to 30°C. Frequency range: 0.1 to 200 rad / s in the linear viscoelastic (LVE) regime.

[0032] Heterogeneous thermoplastic compositions can be applied to substrates as sound-insulating materials. These sound-insulating components can be manufactured using any known method, including injection molding, extrusion, thermoforming, pultrusion, or surface application techniques such as curtain coaters and spray coaters. Heterogeneous thermoplastic compositions may be applied to substrates as a molten material or formed into articles, which are then applied to the substrates by gravity, adhesive, melting, or other suitable techniques.

[0033] Heterophase thermoplastic compositions can be used as sound-dampening or sound-insulating materials that can reduce vibration or sound in noise, vibration, and harshness (NVH) applications, including in automobiles, transportation, flooring, and soundproofing materials. Heterophase thermoplastic compositions can attenuate a single frequency of vibration, all frequencies of vibration, or one or more frequency bands of vibration. For example, heterophase thermoplastic polymers can attenuate vibration frequencies caused by road noise, environmental noise, footsteps, and other impacts. [Examples]

[0034] The following embodiments are provided to illustrate embodiments of the present invention, but are not intended to limit their scope. Table 1 provides the materials used in the following embodiments. All parts and percentages are by weight unless otherwise indicated.

[0035] [Table 1]

[0036] The sample formulations were combined using a Haake 3000 mixer according to the formulations listed in Table 2. After mixing, the resin was placed inside a 165mm × 165mm × 3mm steel window frame mold and nested between two polytetrafluoroethylene sheets. This decorative frame assembly was compressed at 2 tons for 2 minutes, followed by 24 tons and 190°C for 2 minutes. The decorative frame assembly was then placed in a cooling press and molded at 24 tons for 2 minutes. The resulting decorative frame was approximately 3mm thick and 165mm long × 165mm wide.

[0037] [Table 2]

[0038] The sample tests were conducted as follows, and the results are shown in Table 3 (comparative sample) and Table 4 (sample of the present invention).

[0039] Shore A hardness was assessed according to ASTM D2240-21 with a holding time of 10 seconds.

[0040] Tensile properties were tested at room temperature on tensile bars die-cut from decorative frames, according to the ATMM D412-16 Type C.

[0041] Density was tested according to ASTM D792-16.

[0042] The modulus of elasticity and tanδ were measured for bar-torsion specimens. The bar-torsion mode was performed using an ARES-G2 (TA Instruments) with a torsion fixing device. A 12.75 mm wide, 40 mm long specimen strip (3 mm thick) was punched out from a decorative frame and fixed to a clamp. Frequency sweeps were performed using the LVE regime over a range of 0.1 to 200 rad / s at 23°C.

[0043] To conduct the insertion loss test, acoustic simulations were performed on each formulation shown in Tables 3 and 4 to predict performance. In this model, a metal substrate (CRS 0.8 mm) treated with a sound insulation material is sandwiched between a sound source chamber and a receiving chamber. This test apparatus is similar to the "APAMAT" apparatus used by carpet layer suppliers to verify an acoustic package with dimensions of 33'' × 33''. The sound source chamber is excited at both the sound level and the vibration level.

[0044] Using VA-One software, the insertion loss performance is predicted for each of the sound insulation compositions. Insertion loss (IL) is used as a measure of the performance of the sound insulation material and is calculated as the difference in sound pressure level (SPL) in a virtual receiving chamber separated from the sound source chamber, according to the formula IL = SPL スチール -SPL AB and the chambers are separated by a steel substrate, without and with the sound insulation material (AB) (coating the opposing receiving chamber).

[0045] The metal substrate and the sound insulation material are modeled as isotropic materials in these acoustic simulations. The material properties of the sound insulation material are shown in Tables 4 and 5, and for all sound insulation material formulations, the Poisson's ratio is assumed to be 0.49. The surface mass density of all sound insulation materials is kept constant at 4.59 kg / m 2 in each simulation, and the thickness is calculated as appropriate. For example, the thickness of sound insulation material C1 is calculated to be 2.37 [mm] based on a density of 1.94 [g / cc].

[0046] [Table 3]

[0047] [Table 4]

[0048] In each example, C1, C4, and C5 do not contain acrylic additives and exhibit tanδ values ​​below the target threshold of 0.11. C2 and C3 exhibit hardness values ​​higher than the acceptable maximum and elongation at break values ​​lower than the acceptable threshold, which are due to the high matrix density (>40 wt% HDPE).

[0049] In contrast, I1 meets the requirements and has a tanδ that is more than 200% higher than the formulation without acrylic components. Similarly, I2 meets the performance requirements and shows a tanδ that is 130% higher than the formulation without acrylic components. I3 meets the performance requirements and the composition has a moderate matrix density (0.90 g / cc) and a moderate concentration of acrylic components. I4 meets the requirements and has a tanδ that is 100% higher than the equivalent formulation without acrylic components.

[0050] Regarding insertion loss, the tests show that the addition of acrylic components helps improve the acoustic performance of sound insulation materials. For example, C1 (0% acrylic, 0% HDPE) shows performance improvements of 4.5 dB and 2.4 dB compared to I1 (3.75% acrylic, 0% HDPE) and I2 (1.875% acrylic, 0% HDPE), respectively. Furthermore, the inclusion of acrylic resin in the polyolefin elastomer / HDPE mixture shows performance improvements of 0.7 dB and 1.7 dB compared to I3 (1.87% acrylic component, 12.08% HDPE) and I4 (3.75% acrylic component, 10.825% HDPE), as well as the predicted insertion loss performance of C5 (0% acrylic component and 13.3% HDPE).

Claims

1. A heterogeneous thermoplastic composition, A continuous polyolefin phase containing ethylene / α-olefin interpolymer, A composition comprising an acrylic discontinuous phase dispersed in the polyolefin continuous phase at a part count (pphr) of less than 20 pphr per 100 parts of resin, and having a tanδ of 0.11 or more at a frequency of 200 rad / s.

2. The composition according to claim 1, comprising the acrylic discontinuous phase in a range of 0.5 pphr to 20 pphr per 100 parts (pphr) of resin.

3. The composition according to claim 1, wherein the acrylic discontinuous phase is a copolymer of butyl acrylate, styrene, and methacrylic acid.

4. The composition according to claim 1, wherein the acrylic discontinuous phase has a Tg according to Fox's formula in the range of -60°C to 10°C.

5. The composition according to claim 1, further comprising an HDPE homopolymer having a density in the range of 0.94 g / cc to 0.99 g / cc according to ASTM D3574-17, in an amount of 0.1 pphr to 35 pphr per 100 parts (pphr) of resin.

6. The composition according to claim 1, wherein the polyolefin continuous phase has a density of 0.92 g / cc or less according to ASTM D3574-17.

7. The composition according to claim 1, having a density of at least 1.5 g / cc according to ASTM D3574-17.

8. The composition according to claim 1, wherein the acrylic discontinuous phase comprises a non-crosslinked acrylic polymer.

9. An article manufactured from the composition described in claim 1.

10. A method for preparing the composition described in claim 1, Forming a blend by combining polyolefin and acrylic resin, A method comprising heating the blend to form the polyolefin continuous phase in which the acrylic discontinuous phase is dispersed.

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