Regenerated foam articles and methods of making same

Abstract

The present application discloses a multilayer article comprising a first layer, the first layer comprising a first thermoplastic polyolefin. The first layer is in contact with a fourth layer, the fourth layer comprises an olefin polymer having a peak melting point of 130 DEG C to 170 DEG C, the elastic modulus of the first layer is lower than that of the fourth layer, and the elastic modulus is measured according to ASTM D638. The multilayer article can be used as a panel for the interior of an automobile.

Description

Technical Field

[0001] This disclosure relates to recycled foam products and methods for manufacturing the same. Background Technology

[0002] Recycling polymer materials is becoming increasingly important and economically valuable. Significant progress has been made in recycling thermoplastic polymers, but recycling cross-linked (also known as thermoset) materials remains a major challenge. The fact that polymers cannot be remelted once cross-linked has been a major obstacle to recycling cross-linked materials. Furthermore, cross-linked materials, especially cross-linked foams, are often bonded to thermoplastics. Attempting to reuse these materials typically requires separating the thermoplastics from the cross-linked foam, a time-consuming and labor-intensive process. Recycling cross-linked materials involves various chemical methods to reduce the number of crosslinks. These methods are often expensive and can have negative environmental impacts. When these methods are applied to cross-linked foams, there is an additional problem of gas release from the cells, which can negatively affect the final product. Even when cross-linked materials are adequately treated for reuse, residual cross-linking agents can negatively impact the final product.

[0003] There is still a need in the field for a method to reprocess cross-linked materials, particularly foamed cross-linked materials. Summary of the Invention

[0004] This application discloses a multilayer article comprising a first layer comprising a first thermoplastic polyolefin. The first layer is in contact with a fourth layer comprising an olefin polymer with a peak melting point of 130°C to 170°C. The elastic modulus of the first layer is lower than that of the fourth layer, the elastic modulus being measured according to ASTM D638. This multilayer article can be used as a panel in an automotive interior.

[0005] This application discloses a method for preparing a multilayer article, the method comprising: extruding a first layer comprising a first thermoplastic polyolefin; unwinding a fourth layer from a feed roll, wherein the fourth layer comprises an olefin polymer having a peak melting point of 130°C to 170°C, and the elastic modulus of the first layer being lower than that of the fourth layer; and feeding the first layer and the fourth layer into the roll gap of a roller mill, and laminating the first layer and the fourth layer in the roll gap to form a multilayer article.

[0006] This application also discloses a method for recycling multi-layered articles, the method comprising:

[0007] Crushing a multi-layered product (A), said multi-layered product (A) comprising:

[0008] a) A first layer, the first layer comprising a first thermoplastic polyolefin; and

[0009] b) A fourth layer comprising an olefin polymer with a peak melting point of 130°C to 170°C; or

[0010] Crushing a multi-layered product (B), the multi-layered product (B) comprising:

[0011] i) A first layer comprising a first thermoplastic polyolefin;

[0012] ii) A second layer comprising a second thermoplastic polyolefin;

[0013] iii) A third layer comprising a third thermoplastic polyolefin; and

[0014] iv) A fourth layer comprising an olefin polymer with a peak melting point of 130-170°C. The first thermoplastic polyolefin differs from the second thermoplastic polyolefin.

[0015] In a melt processing machine, powder corresponding to a multilayer product (A) or powder corresponding to a multilayer product (B) to be pulverized is melt-blended with an additional thermoplastic polyolefin; wherein the powder made from the pulverization of the multilayer product (A) and the multilayer product (B) each comprises at least 50 wt% thermoplastic polyolefin. Attached Figure Description

[0016] Figure 1 This is an exemplary schematic diagram of a multi-layered product;

[0017] Figure 2 This is an exemplary simplified schematic diagram of a method for preparing multilayer articles;

[0018] Figure 3 yes Figure 1 A schematic diagram of an exemplary multilayer article; wherein the multilayer article is bonded to a crosslinked polypropylene and a thermoplastic polyolefin substrate. Detailed Implementation

[0019] definition

[0020] Cellular structure refers to the cellular structure inside a foam material, in which air bubbles are encased within a solid matrix, thus forming a lightweight porous structure.

[0021] Cross-linked polypropylene (sometimes referred to by its abbreviation XLPP) is commonly used in applications such as automotive parts, insulation materials, and foam products, particularly in scenarios requiring durability and stability under harsh conditions. It is a modified form of polypropylene (PP) in which covalent bonds, or "crosslinks," are formed between polymer chains. This crosslinking process improves the material's properties by enhancing its resistance to thermal, chemical, and mechanical stresses. It essentially strengthens the material's structure, providing better resistance to heat distortion, impact, and cracking, while also improving its durability under long-term exposure to extreme conditions. Cross-linked polypropylene foam is a specialized material known for use in industries requiring lightweight, durable, and insulating properties.

[0022] The term "olefin" refers to a class of hydrocarbons containing at least one carbon-carbon double bond (C=C). Olefins are polymerized to produce polyolefins.

[0023] Polyolefins are sometimes referred to as "olefin polymers" in this article.

[0024] Detailed description

[0025] This document discloses a multilayer article that functions similarly to artificial leather and can be used as a panel in an automobile. The panel has a soft touch and can be used alone in automotive interiors (resulting in a flexible and flexible component) or in combination with a rigid backing (resulting in a rigid component). In one embodiment, the multilayer article may comprise two or more layers, preferably three or more layers, more preferably four or more layers (multilayer article), wherein each layer comprises a thermoplastic polyolefin. Based on the total weight of each layer, the thermoplastic polyolefin content in each layer is greater than 50 wt%. In one embodiment, based on the total weight of the multilayer article, the thermoplastic polyolefin content in the multilayer article is greater than 50 wt%, preferably greater than 55 wt%, and more preferably greater than 60 wt%.

[0026] The polyolefins used in each layer can be thermoplastic or crosslinked (sometimes referred to as thermoset). In one embodiment, the polyolefin used for each layer is a thermoplastic polyolefin. This makes the multilayer article easy to recycle. Because each layer includes a polyolefin, the multilayer article can be easily recycled and reused (during or after its life cycle), thereby minimizing material loss in landfills.

[0027] This application also discloses a method for manufacturing a multilayer article. In one embodiment, a first method for manufacturing a multilayer article includes: co-extruding at least two or more layers, preferably three or more layers (each layer comprising a polyolefin) to form a first laminate. The first laminate is then bonded to a fourth layer (hereinafter referred to as a "backing layer"), also comprising a polyolefin, in a roll mill to form a multilayer article. In one embodiment, the fourth layer comprises an olefin polymer with a peak melting point of 130 to 170°C.

[0028] This application also discloses a method for recycling multilayer articles. In use, the multilayer article can optionally be disposed on a cross-linked polypropylene foam (sometimes referred to as XLPP foam) and / or a rigid thermoplastic polyolefin substrate (sometimes referred to as a TPO substrate) (which acts as a carrier) to form a rigid multilayer article. The cross-linked polypropylene foam and the rigid thermoplastic polyolefin substrate provide strength and impart geometry to the multilayer article (a combination of the first layer 102 and any of the remaining layers 104, 106, and 108), thereby forming a three-dimensional object suitable for automotive interiors. Thus, the rigid multilayer article has a soft surface provided by layer 102 while possessing structural rigidity and the ability to bear loads when needed (due to the cross-linked polypropylene foam and / or the rigid thermoplastic polyolefin substrate). In one embodiment, the thermoplastic polyolefin content in the multilayer article is greater than at least 50 wt%, preferably greater than 55 wt%, and more preferably greater than 60 wt%, based on the total weight of the rigid multilayer article.

[0029] Multilayer or rigid multilayer products can be easily recycled as a whole to produce recycled pellets, which can be partially used to manufacture the multilayer products disclosed herein. Since each layer of a rigid multilayer product comprises a polyolefin, complete recycling can be easily achieved in a single process without generating significant waste. Furthermore, the lack of extensive crosslinking materials in multilayer or rigid multilayer products minimizes phase separation between the various polymer components added during recycling, facilitating the conversion of recycled material into reusable thermoplastic polyolefins. The substantial absence of polymers other than polyolefins in multilayer or rigid multilayer products minimizes phase separation, inhomogeneity, and incompatibility during reprocessing, thereby reducing waste and defects typically generated. Minimal material is required for landfill disposal. The recycled polyolefins can then be used for… Figure 1 and Figure 3 In any layer of the multilayer product shown.

[0030] Figure 1This is an exemplary schematic diagram of a multilayer article 100. The multilayer article 100 includes multiple layers, layer 102, layer 104, layer 106, and layer 108, wherein the composition of at least one layer differs from that of at least one other layer. In one embodiment, the multilayer article includes at least one layer 102 (referred to herein as first layer 102) in contact with layer 108 (referred to herein as fourth layer 108). In one embodiment, the article includes at least two distinct layers: first layer 102 and second layer 104 disposed on fourth layer 108, but may also include at least three layers disposed on fourth layer 108: first layer 102, second layer 104, and third layer 106. Layers 104 and 106 may be optional layers (e.g., the multilayer article 100 may not include these layers). In a preferred embodiment, the multilayer article includes at least four distinct layers: first layer 102, second layer 104, third layer 106, and fourth layer 108. Each of the four different layers: first layer 102, second layer 104, third layer 106, and fourth layer 108, comprises a polyolefin. In one embodiment, first layer 102, second layer 104, and third layer 106 comprise a thermoplastic elastomer. In yet another embodiment, first layer 102 or second layer 104 comprises a foamed thermoplastic elastomer.

[0031] from Figure 1 It can be seen that the first layer 102 is in direct contact with the second layer 104, while the second layer 104 (when present) is in direct contact with the first layer 102 and the third layer 106 on its two opposite surfaces. The third layer 106 is in direct contact with the second layer 104 and the fourth layer 108 on its opposite surfaces. The fourth layer 108 is in direct contact with the third layer 106 on at least one surface. Figure 1 As can be seen from this, in one embodiment, the first layer 102 and the fourth layer 108 are the outer layers of the multilayer article.

[0032] As will be explained in detail below, each of the above layers (first layer 102, optional second layer 104, optional third layer 106 and fourth layer 108) can be disposed on cross-linked polypropylene foam.

[0033] In one embodiment, each of the first layer 102, the second layer 104, and the third layer 106 may have the same or different chemical compositions, although their physical structures may differ. For example, the first layer 102 and the third layer 106 may have the same or different thicknesses, but both are solid films (substantially non-porous), while the second layer 104 is a foamed layer (with a porosity greater than 25%, preferably greater than 40%, more preferably greater than 50% by volume), and its thickness may differ from that of the first layer 102 or the third layer 106. All these features will be discussed below.

[0034] In one embodiment, the elastic modulus of the first layer 102 and optionally the third layer 106 is higher than that of the second layer 104, which comprises foam. The elastic modulus of the fourth layer 108 is higher than that of the first layer 102, the second layer 104, and the third layer 106. All elastic moduli are determined according to ASTM D638.

[0035] The composition of the first layer 102d may be the same as or different from that of the third layer 106. The third layer 106 may be optional. Layers 102 and 106 are elastic (each with an elastic modulus greater than or equal to 0.01 MPa and less than 100 MPa, preferably less than 10 MPa, as determined by ASTM D638) and may each include a thermoplastic elastomer. In one embodiment, the first layer 102 may include a first thermoplastic elastomer, while the third layer 106 may include a third thermoplastic elastomer. In one embodiment, the chemical composition of the first thermoplastic elastomer may be the same as that of the third thermoplastic elastomer. In another embodiment, the chemical composition of the first thermoplastic elastomer may be different from that of the third thermoplastic elastomer.

[0036] The first thermoplastic elastomer includes a propylene-based elastomer, a vinyl elastomer, polypropylene, and a filler. In one embodiment, the filler may be optional. The first layer 102 and the third layer 106 each comprise at least 50% by weight of a thermoplastic olefin polymer, and both are in the form of a solid film without any significant pores. Both layers 102 and 106 comprise flexible films. Preferably, the flexible film has a soft touch.

[0037] As used herein, the term "propylene-based elastomer" refers to a polymer that comprises more than 50% molar amount of polymeric propylene monomers (based on the total amount of polymerizable monomers) and includes at least one comonomer.

[0038] In the embodiments described herein, the propylene-based elastomer is a propylene copolymer, or a combination of a polypropylene homopolymer and a polypropylene copolymer. In some embodiments, the propylene-based elastomer is a propylene / olefin copolymer. The polypropylene homopolymer may be isotactic, atactic, or syndiotactic. In some embodiments, the propylene-based elastomer is an isotactic polypropylene homopolymer.

[0039] The propylene / olefin copolymer can be a random copolymer or a block copolymer. The propylene / olefin copolymer includes: (a) propylene-derived units comprising less than or equal to 100% by weight, such as at least 70%, at least 80%, at least 90%, at least 92%, or at least 95% by weight of propylene-derived units; and (b) units comprising less than 30% by weight of units derived from one or more α-olefin comonomers, such as less than 25%, less than 20%, less than 10%, less than 8%, or less than 5% by weight of units derived from one or more α-olefin comonomers. In further embodiments, the propylene-based elastomer can be a combination of one or more propylene homopolymers, one or more propylene copolymers, or a combination of one or more propylene homopolymers and one or more propylene copolymers.

[0040] In embodiments where the propylene-based elastomer comprises at least one α-olefin comonomer, the α-olefin comonomer has no more than 20 carbon atoms. For example, the α-olefin comonomer may have 3 to 10 carbon atoms, or 3 to 8 carbon atoms. Exemplary α-olefin comonomers include, but are not limited to, ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and 4-methyl-1-pentene. One or more α-olefin comonomers may, for example, be selected from the group consisting of ethylene, 1-butene, 1-hexene, and 1-octene; or, alternatively, from the group consisting of ethylene. In the embodiments herein, the propylene-based elastomer may be (or may not be) a homopolymer, copolymer, or interpolymer.

[0041] Propylene-based elastomers can be prepared using any method for polymerizing propylene and optionally a comonomer. For example, gas-phase, bulk or slurry-phase, solution polymerization, or any combination thereof can be used. The polymerization can be a one-stage, two-stage, or multi-stage process carried out in at least one polymerization reactor. For two-stage or multi-stage processes, different combinations can be used, such as gas-gas phase, slurry-slurry phase, or slurry-gas phase processes. Suitable catalysts may include Ziegler-Natta catalysts, single-center catalysts (metallocene or confined geometry), or non-metallocene, metal-center, heteroaryl ligand catalysts, or combinations thereof.

[0042] Based on the total weight of the first layer 102 or the third layer 106, the content of the propylene-based elastomer in the first layer 102 or the third layer 106 can be 50 to 70 wt%, preferably 55 to 65 wt%.

[0043] In addition to the propylene-based elastomer, the first layer 102 or the third layer 106 also includes a vinyl elastomer. This vinyl elastomer comprises: (a) units derived from ethylene at a weight percentage of less than or equal to 100%, such as at least 70%, 80%, 90%, 92%, or 95% by weight of units derived from propylene; and (b) units derived from one or more α-olefin comonomers at a weight percentage of less than 30%, such as at least 25%, 20%, 10%, 8%, or 5% by weight of units derived from one or more α-olefin comonomers. As used herein, the term "vinyl elastomer" refers to a polymer comprising more than 50% by molar amount of polymerizable ethylene monomers (based on the total amount of polymerizable monomers), and optionally may comprise at least one comonomer.

[0044] In embodiments where the vinyl elastomer comprises at least one α-olefin comonomer, the α-olefin comonomer has no more than 20 carbon atoms. For example, the α-olefin comonomer may have 3 to 10 carbon atoms, or 3 to 8 carbon atoms. Exemplary α-olefin comonomers include, but are not limited to, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and 4-methyl-1-pentene. One or more α-olefin comonomers may, for example, be selected from the group consisting of propylene, 1-butene, 1-hexene, and 1-octene; or, alternatively, from the group consisting of 1-hexene and 1-octene. In the embodiments herein, the vinyl elastomer may be (or may not be) a homopolymer, copolymer, or interpolymer.

[0045] Vinyl elastomers can be prepared by gas-phase, solution-phase, or slurry polymerization, or any combination thereof, using any type of reactor or reactor configuration known in the art, such as fluidized bed gas-phase reactors, loop reactors, stirred tank reactors, parallel and / or series batch reactors, or any combination thereof. In some embodiments, a gas-phase reactor or a solution reactor is used. Catalysts used to prepare the vinyl elastomers described herein may include Ziegler-Natta, metallocene, confined geometry, single-center catalysts, or combinations thereof. For example, vinyl elastomers may be LLDPEs, such as znLLDPE (referring to linear polyethylene prepared using a Ziegler-Natta catalyst), uLLDPE (or “ultra-linear low-density polyethylene,” which may include linear polyethylene prepared using a Ziegler-Natta catalyst), or mLLDPE (referring to LLDPE produced using polyethylene prepared using a metallocene or confined geometry catalyst).

[0046] Based on the total weight of the first layer 102 or the third layer 106, the content of the vinyl elastomer used in the first layer 102 or the third layer 106 can be from 10 wt% to 30 wt%, preferably from 15 wt% to 25 wt%.

[0047] The first layer 102 and the third layer 106 also include a polypropylene homopolymer. It should be noted that this polypropylene homopolymer is additionally added and is different from any polypropylene homopolymer detailed above that may be a component of a propylene-based elastomer. The polypropylene homopolymer can be isotactic, atactic, or syndiotactic. In some embodiments, the polypropylene homopolymer is an isotactic polypropylene homopolymer. The polypropylene homopolymer may also include a small amount of random copolymer polypropylene (i.e., a copolymer of propylene with ethylene, or with an α-olefin comonomer having 3 to 20 carbon atoms), injection-molding grade polypropylene, or high melt strength polypropylene. α-olefin comonomers having 3 to 20 carbon atoms have been listed above and will not be repeated here for brevity. In one embodiment, the high melt strength polypropylene is prepared using polypropylene with a long-chain branched structure. In one embodiment, long-chain branching can be formed by electron beam irradiation, reactive compounding, or a combination thereof.

[0048] Based on the total weight of the first layer 102 or the third layer 106, the content of polypropylene homopolymer used in the first layer 102 or the third layer 106 is 5 wt% to 25 wt%, preferably 10 wt% to 20 wt%.

[0049] The first layer 102 and / or the third layer 106 may also include fillers and additives. "Fillers" include reinforcing fillers such as glass fibers and beads, carbon fibers, carbon nanotubes, carbon black, polymer fibers (e.g., polyester fibers, polyaramid fibers, polyimide fibers, polyetherimide fibers, etc., or combinations thereof), clay, etc., or combinations thereof. These fillers may be in the form of nanoparticles (average particle size less than 100 nanometers) or micron-sized particles (average particle size greater than or equal to 100 nanometers). The fillers may have a unimodal or multimodal (e.g., bimodal, trimodal, etc.) particle size distribution.

[0050] In addition, the first layer 102 and / or the third layer 106 may also include additives, such as: antistatic agents, color enhancers, dyes, lubricants, fillers (such as TiO2 or CaCO3), opacifiers, nucleating agents, processing aids, pigments, primary antioxidants, secondary antioxidants, UV stabilizers, anti-caking agents, slip agents, tackifiers, flame retardants, antimicrobial agents, odor eliminators, antifungal agents, and combinations thereof.

[0051] The amount of one or more fillers and additives added to the first layer 102 and / or the third layer 106 may be at levels commonly used in the art to achieve their intended purpose. In some instances, the content of one or more additives is 0 to 10 wt%, 1 to 5 wt%, and 1.5 to 4 wt% of the total weight of the first layer 102 and / or the third layer 106, respectively.

[0052] As described above, the first layer 102 can be directly disposed on the fourth layer 108, or alternatively disposed on the second layer 104 and the third layer 106. When the first layer 102 is directly bonded to the fourth layer 108, its thickness is 0.10 to 0.7 mm, preferably 0.2 to 0.6 mm.

[0053] When the first layer 102 is bonded to the second layer 104 and the third layer 106, the first layer 102 and the optional third layer 106 may have the same thickness, or the thickness of one layer may be different from that of the other. In one embodiment, the thickness of the first layer 102 is 0.05 to 0.35 mm. In one embodiment, the thickness of the third layer 106 is 0.05 to 0.35 mm.

[0054] Preferably, the second layer 104 is a foamed layer comprising a second thermoplastic elastomer. The second thermoplastic elastomer may be the same as or different from the first thermoplastic elastomer (used in the first layer 102) or the third thermoplastic elastomer (used in the third layer 106). Preferably, the second layer 104 is a foamed layer that includes the same components as the first layer 102 and the third layer 106, except for a blowing agent and / or a nucleating agent (before foaming) used to promote cell formation during foam formation. After the foaming process is complete, residues of the blowing agent and nucleating agent may remain in the foam. The foam may be an open-cell foam, a closed-cell foam, or a foam that combines both. In one embodiment, the foam is preferably a closed-cell foam. Depending on the application, the foam may be a flexible foam or a rigid foam. In a preferred embodiment, the foam is a flexible foam comprising a thermoplastic polyolefin. The foamed layer 104 is not crosslinked.

[0055] The foaming agent can be a physical foaming agent, a chemical foaming agent, or a combination of both. In a preferred embodiment, the foaming agent is a chemical foaming agent. The two types of foaming agents will be described below.

[0056] Physical foaming agents typically produce foam by undergoing phase separation from the dissolved organic polymer when environmental conditions change. Chemical foaming agents, on the other hand, react or decompose when environmental conditions change, releasing gases and thus forming foam.

[0057] Foaming agents are substances capable of creating cellular structures in various materials (e.g., organic polymers) undergoing hardening or phase change through a foaming process. They are typically used when the foaming material (e.g., organic polymer) is in a liquid or molten stage. The cellular structure in the polymer reduces density while increasing the relative stiffness of the original organic polymer. Foaming agents or related mechanisms used to create pores in a matrix to manufacture porous materials (cellular materials) are classified as follows:

[0058] Physical blowing agents include chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrocarbons (e.g., pentane, butane, isopentane, cyclopentane, etc.), and liquid or supercritical carbon dioxide.

[0059] The formation of bubbles / foam is irreversible and endothermic, meaning it requires heat (e.g., from the melting process or the chemical exothermics generated by crosslinking) or pressure changes to cause the liquid foaming agent to evaporate.

[0060] Chemical blowing agents include azodicarbonamide, hydrazine, and other nitrogen-based organic polymers used in thermoplastic and elastomeric polymer foams, and sodium bicarbonate used in other thermoplastic polymer foams. Gaseous products and other byproducts are formed by the chemical reaction of the blowing agents, a reaction facilitated by the heat generated during foam production or the exothermic reaction of the polymers. Additional heat is released as the foaming reaction occurs simultaneously with the formation of low-molecular-weight compounds used as the blowing gas.

[0061] Mixed physical / chemical blowing agents can also be used to produce foamed organic polymers. Here, chemical and physical blowing agents are used in synergy to balance each other in terms of heat release and absorption, thereby minimizing the temperature rise of the organic polymer and preventing its thermal degradation.

[0062] Suitable examples of physical foaming agents include fluoromethane, chloromethane, difluoromethane, dichloromethane, perfluoromethane, etc.; hydrocarbons such as acetylene, ammonia, butane, butene, isobutane, isobutene, propane, dimethylpropane, ethane, methane, trimethylamine, pentane, cyclopentane, hexane, propane, propylene, alcohols, ethers, ketones, etc.; or combinations thereof.

[0063] In another embodiment, thermally expandable microspheres can be used as a blowing agent. The microspheres consist of an airtight polymer shell (e.g., polyacrylonitrile or polyvinylidene chloride) encapsulating a (cyclic) aliphatic hydrocarbon (e.g., liquid isobutylene). When the thermally expandable microspheres are subjected to temperatures from about 50°C to about 200°C, the polymer shell softens and the (cyclic) aliphatic hydrocarbon expands, thereby promoting an increase in the volume of the microspheres. During expansion, the diameter of the microsphere is 3.5 to 4 times its original diameter, thus its expanded volume is approximately 50 to 60 times larger than its initial volume in its unexpanded state. One example of such thermally expandable microspheres is those sold by Nouryon. DU microspheres.

[0064] Based on the total weight of the second layer 104, before foaming, the content of the foaming agent in the second layer is 1 to 5 wt%, preferably 1.25 to 2.0 wt%. Based on the total weight of the foamed second layer 104, the residual foaming agent (the amount of residual agent in the foam after foaming) is 0.01 to 2 wt%.

[0065] The second layer 104 may also include a nucleating agent. Nucleating agents are typically used in conjunction with chemical foaming agents. They promote the nucleation of cells, which eventually grow through binode decomposition to form foam. Nucleating agents used in polymer foaming are additives that promote bubble formation during the foaming process, resulting in a more uniform cell structure and improved mechanical properties. These additives help control the size, distribution, and density of foam cells, thereby improving the final properties of the polymer foam. Examples of nucleating agents include talc, calcium carbonate, silica, sodium bicarbonate, organic salts, clay, titanium dioxide, metal oxides (e.g., zinc oxide, magnesium oxide, etc.), carbon dioxide gas, nitrogen gas, or combinations thereof.

[0066] Based on the total weight of the second layer 104, the content of the pre-foaming nucleating agent in the second layer 104 can be selected from 0.5 to 2.5 wt%, preferably 1 to 2 wt%.

[0067] In one embodiment, a foam may be prepared by first mixing a polymer with a suitable blowing agent, so that the polymer-blowing agent combination exists in a single-phase form. The polymer-blowing agent combination is maintained at pressure and temperature that effectively keeps it single-phase until it is ready for use. If needed, the composition is pumped through a die or poured into a mold cavity, and the pressure and / or temperature are varied to promote the decomposition of two nodes, thereby achieving the nucleation and growth of intracellular cells in the polymer, ultimately forming a foam. When the pressure and / or temperature in the mold cavity changes, the blowing agent nucleates and grows in the polymer matrix, thereby forming a polymer foam.

[0068] Alternatively, when using chemical blowing agents, the polymer-blowing agent composition is maintained at pressure and temperature that effectively keeps it in a single phase until it is ready for use. When needed, the composition is pumped through a die or poured into a mold cavity, and the pressure and / or temperature are varied to promote the decomposition of the blowing agent, which releases gas, leading to the nucleation and growth of cells in the polymer, forming foam.

[0069] In one embodiment, the thickness of the second layer 104 is 0.15 to 0.90 mm.

[0070] The volume fraction of porosity in the second layer 104 is 60% to 90%, preferably 70% to 88%, and more preferably 75% to 85%. The average size of the pores varies between 15 and 100 micrometers.

[0071] In one embodiment, the fourth layer 108 comprises an olefin polymer having a peak melting point of 130 to 170°C. The fourth layer 108 (sometimes referred to as the backing layer) typically comprises a polypropylene homopolymer or a polypropylene copolymer. Both polypropylene homopolymers and polypropylene copolymers have been described in detail above and will not be repeated here for the sake of brevity.

[0072] The fourth layer 108 can be a solid film or a woven or nonwoven textile. In one embodiment, the fourth layer 108 is a circular knit. Circular knit is a type of fabric produced using a circular knitting machine (rather than a flat knitting machine). During circular knitting, the fabric is woven into a continuous tubular shape, with the machine's needles moving up and down simultaneously in a circular motion. This tubular fabric is then cut along its length. It can then be washed / finished on a tenter frame. The resulting fabric is seamless and elastic, with a wide range of applications, especially suitable for garments requiring comfort and flexibility. The elastic modulus of the fourth layer 108 is typically higher than that of the first layer 102.

[0073] In one embodiment, when the first layer 102 is directly bonded to the fourth layer 108, the thickness of the fourth layer is 0.3 to 1.2 mm, preferably 0.5 to 0.9 mm. On the other hand, when the first layer is bonded to the fourth layer through the second and third layers, the thickness of the fourth layer is 0.1 to 0.5 mm, preferably 0.15 to 0.45 mm.

[0074] In one embodiment, in one manner of manufacturing the multilayer article 100, the composition for the first layer 102, and optionally the second layer 104 and the third layer 106, is disposed in three separate extruders 202, 204 and 206, as follows: Figure 2 As shown. Figure 2 This is a simplified schematic diagram of an exemplary manufacturing apparatus for manufacturing a multilayer article 100. The first layer 102 and the third layer 106 can be extruded into solid films, while the second layer 104 can be extruded into foam.

[0075] The first layer 102, and optional layers 104 and 106, can be co-extruded together with the fourth layer 108 into the "roll gap" of a roller mill. By adjusting the "roll gap" (i.e., the distance between the relatively positioned roller mills 210 and 212), the required pressure is applied to the first to fourth layers (102, optional 104, optional 106, and 108), thereby forming a multilayer product. The fourth layer 108 can be unwound from the feed roller 208 and fed into the roll gap. Alternatively, it can be co-extruded and then fed into the roll gap, and laminated to form a multilayer product 100. Figure 1 and Figure 3 As can be seen, the first and fourth layers are located on the outer surfaces of the second and third layers, respectively. The inner surface of the second layer is in contact with the inner surface of the third layer.

[0076] The roller mill can be a two-roll mill or a three-roll mill. A three-roll mill is preferred. During the rolling process, the pressure applied to each layer should be sufficient to promote lamination and provide suitable bond strength between the layers (102 to 108) without compromising the quality of the second layer 104 (foamed layer). Excessive compressive force within the roll gap will reduce the porosity of the foamed layer, which is undesirable.

[0077] In one embodiment, a multilayer article comprising two to four layers is arranged on a cross-linked polypropylene foam (sometimes referred to as XLPP foam) and / or a rigid thermoplastic polyolefin substrate (sometimes referred to as TPO substrate) (which serves as a carrier) to form a rigid multilayer article. The cross-linked polypropylene layers may be foam, or alternatively, non-porous solid layers. Figure 3 A multilayer article 100 is depicted, which is bonded to a cross-linked polypropylene layer 302 and a rigid thermoplastic polyolefin substrate 304 to form a rigid multilayer article 400.

[0078] In one embodiment, the multilayer article 100 can be bonded to the cross-linked polypropylene layer 302 and the rigid thermoplastic polyolefin substrate 304 by a cutting, sewing and wrapping process. When the multilayer article 100 is bonded to the cross-linked polypropylene layer 302 and the rigid thermoplastic polyolefin substrate 304 by the cutting, sewing and wrapping process, the thickness of the cross-linked polypropylene layer 302 is 1.0 to 1.5 mm, preferably 1.1 to 1.4 mm; while the thickness of the rigid thermoplastic polyolefin substrate 304 is 2.0 to 3.0 mm, preferably 2.2 to 2.8 mm.

[0079] In another embodiment, the multilayer article 100 can be bonded to the cross-linked polypropylene layer 302 and the rigid thermoplastic polyolefin substrate 304 by a thermoforming process. When the multilayer article 100 is bonded to the cross-linked polypropylene layer 302 and the rigid thermoplastic polyolefin substrate 304 by a thermoforming process, the thickness of the cross-linked polypropylene layer 302 is 2.0 to 3.0 mm, preferably 2.2 to 2.8 mm; while the thickness of the rigid thermoplastic polyolefin substrate 304 is 2.0 to 3.0 mm, preferably 2.2 to 2.8 mm. The thickness of the film and the thickness of each individual layer are measured in a direction perpendicular to the direction in which the extrudate flows out of the extruder die.

[0080] In one embodiment, the multilayer or rigid multilayer article can be recycled at the end of its service life. Since the entire multilayer article comprises polyolefin, full recycling is possible without discarding any portion due to incompatibility. As mentioned above, the thermoplastic polyolefin content is greater than 50 wt%, preferably greater than 55 wt%, and more preferably greater than 60 wt%, based on the total weight of the multilayer or rigid multilayer article. This improves recycling efficiency and reduces waste generated due to incompatibility with downstream materials during recycling.

[0081] In one embodiment, the used multilayer or rigid multilayer article may optionally be shredded in a shredder to a size conducive to introduction into the hopper of an extruder. The shredded article is then fed together with other thermoplastic polyolefins (such as those described above) into a melt processing apparatus to produce a new thermoplastic polyolefin blend, which can be reused. Figure 1 and Figure 3 The multi-layered product shown.

[0082] Suitable melt processing equipment includes extruders, both single-screw and multi-screw extruders. In addition to this requirement, depending on the target application of the melt-processable material, multilayer (or rigid multilayer) products may require more stringent processing conditions to control the trapped gas content in the melt-processable material to the desired level. For example, for sheet applications, the average particle size of the processed multilayer (or rigid multilayer) product is required to be less than or equal to the average cell size of the polymer foam (i.e., the second layer 104). Properties (such as hardness) can be customized based on the average particle size of the processed material. Processed foams with a larger average particle size, due to the higher trapped gas content in the melt during processing, can result in a softer touch or a unique feel / appearance. Conversely, for extremely demanding applications, multilayer (or rigid multilayer) products may require a very small average particle size to ensure that the trapped gas content is negligible during thermal processing. Processing methods include any process that yields a suitable particle size, such as shredding, grinding, cryogenic grinding, or combinations thereof. In addition to the exemplary processes described above, separation, compaction (i.e., densification) or mixing (e.g., incorporating abrasives to help reduce particle size) may also be employed.

[0083] In melt-mixing conditions, the domain size of a processed multilayer product (or rigid multilayer product) is less than or equal to the processing space size of the melt processing equipment. Domain size is defined as the volume occupied by a discrete portion of the material in the processed multilayer product (or rigid multilayer product). Domains may or may not include trapped gases. Under melt-mixing conditions, the shape of domains may be regular or irregular. Furthermore, domains can deform under melt-mixing conditions to pass through the processing space. The processing space is defined as the spaces through which the melt-mixed material flows. For example, in an extruder, the processing space will include the barrel (particularly the space between the screw and barrel), the melt filter (if used), and the orifices in the die (if used). Under melt-mixing conditions, the domain size is less than or equal to the minimum processing space of the melt processing equipment to prevent clogging and blockage.

[0084] During recycling, thermoplastic materials and optional compatibilizers are combined with processed multilayer (or rigid multilayer) materials in a melt-processing apparatus. The desired properties of the melt-processable material will ultimately depend on the specific material system. The added material should be easily melt-processable and, ideally, fully compatible with all existing materials. For example, propylene-ethylene copolymers (e.g., thermoplastic polyolefins) would be suitable thermoplastic polymers to add to systems containing cross-linked polypropylene foam or cross-linked polypropylene foam bonded to a polyethylene surface. In this document, a compatibilizer is defined as an additive that promotes the distribution of the processed multilayer (or rigid multilayer) material throughout the melt-processable polymer matrix and stabilizes the morphology of the final product. The choice of compatibilizer depends on the composition of the processed multilayer (or rigid multilayer) material and the composition of the matrix of the final product. Polymer compatibilizers include block / graft copolymers, polymers with polar side groups, and reactive functional polymers. Reactive compounds that facilitate in-situ formation of copolymers (reactive compatibilizers) are also considered. Examples of such reactive compatibilizers include unsaturated carboxylic acids, etc.

[0085] Examples of unsaturated carboxylic acids include maleic acid, fumaric acid, itaconic acid, methacrylic acid, crotonic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, citraconic acid, etc., or combinations thereof. Examples of derivatives of unsaturated carboxylic acids include maleic anhydride, citraconic anhydride, itaconic anhydride, malonic anhydride, succinic anhydride, glutaric anhydride, adipic anhydride, pimelic anhydride, octanoic anhydride, azelaic anhydride, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, glycidyl acrylate, glycidyl methacrylate, etc., or combinations thereof. Maleic anhydride is a preferred grafting compound.

[0086] When the processed material already includes a processed thermoplastic material (such as the multilayer or rigid multilayer articles described herein), it may not be necessary to add additional thermoplastic material, although additional material may still be added. If the composition includes additional thermoplastic material, this material may be the same as or different from the processed thermoplastic material. For example, if the processed thermoplastic material is polyethylene, the additional thermoplastic material may be polyethylene, polypropylene, or a polyolefin copolymer. As mentioned above, compatibilizers may also be incorporated into the melt-blended composition.

[0087] During melt mixing, the design and / or conditions of the melt processing equipment are selected to minimize or eliminate the effects of any residual foaming agents, crosslinking agents, or combinations thereof. Rheology modifiers may also be included in the melt-mixed composition to aid in the extraction of volatiles during melt mixing. Modifying the rheology of the melt-mixed composition facilitates the removal of volatiles using vacuum. After volatile removal, rheology modifiers can also increase the viscosity and / or melt strength of the composition. Common rheology modifiers include commercially available plasticizers that enhance material flowability. Certain classes of plasticizers include linear or branched phthalates, trimellitics, adipates, polymers, and terephthalates. Processing conditions that affect the quality of the final material include, but are not limited to: screw design, screw speed, barrel temperature distribution, die design, pellet size, use of underwater pelletizers, tool design, and cutting speed.

[0088] It is also conceivable that processed polymer materials can be melt-blended to form granulated processed polymer materials, which can then be melt-blended with additional thermoplastic materials. Similarly, processed cross-linked polymer foams can be melt-blended with a first thermoplastic to form granulated materials, and then the granulated materials can be melt-blended with a second thermoplastic to form a melt-processable material. Rheology modifiers and compatibilizers can be added in any melt-blending step.

[0089] In one embodiment, the recycled thermoplastic polyolefin can be reused. Figure 1 and 3 In any layer of the multilayer article described herein.

[0090] Generally speaking, the present invention may alternatively include, consist of, or be substantially composed of any suitable components disclosed herein. The present invention may additionally or alternatively be formulated to be free of, or substantially free of, any components, materials, ingredients, excipients, or substances used in prior art compositions or unnecessary for achieving the function and / or purpose of the present invention.

[0091] All ranges disclosed herein include endpoint values, and the endpoint values ​​can be combined independently of each other (e.g., the range of "up to 25 wt%, or more specifically 5 wt% to 20 wt%" includes the endpoint values ​​of the range of "5 wt% to 25 wt%" and all intermediate values, etc.).

[0092] "Combination" includes blends, mixtures, alloys, reaction products, and similar forms. Furthermore, the terms "first," "second," etc., used herein do not indicate any order, quantity, or importance, but are used to distinguish different elements. The terms "an," "a," and "the" used herein do not constitute a limitation on quantity and should be interpreted as encompassing both the singular and plural forms, unless otherwise expressly stated herein or the context clearly contradicts it. The suffix "(s)" used herein is intended to encompass both the singular and plural forms of the term it modifies, i.e., to include one or more of the term (e.g., "membrane" encompasses one or more membranes). References throughout this specification to "an embodiment," "another embodiment," "a particular embodiment," etc., indicate that a specific element (e.g., feature, structure, and / or property) described in connection with that embodiment is included in at least one embodiment described herein and may or may not appear in other embodiments. Furthermore, it should be understood that the described elements may be combined in any suitable manner in the various embodiments.

[0093] Although specific embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents may emerge that are currently unforeseeable to the applicant or others skilled in the art. Therefore, the appended claims, as well as any subsequent amendments, are intended to cover all such alternatives, modifications, variations, improvements, and substantial equivalents.

Claims

1. A multi-layer article comprising: a first layer, the first layer comprising a first thermoplastic polyolefin; wherein the first layer is in contact with a fourth layer, the fourth layer comprising an olefin polymer having a peak melting point of 130°C to 170°C; the first layer has a lower modulus of elasticity than the fourth layer, the modulus of elasticity being measured according to ASTM D638; the multi-layer article is useful as a panel for an automotive interior.

2. The multilayer article of claim 1, wherein, the first thermoplastic polyolefin comprises a propylene-based elastomer in an amount of 50 to 70 wt% and an ethylene-based elastomer in an amount of 10 to 30 wt%, based on the total weight of the first layer.

3. The multilayer article of claim 1, further comprising a second layer, wherein, the second layer is disposed between the first layer and the fourth layer, the second layer comprising a foam, the foam comprising a second thermoplastic polyolefin; the second thermoplastic polyolefin is chemically different from the first thermoplastic polyolefin.

4. The multilayer article of claim 3, wherein, the second thermoplastic polyolefin comprises a propylene-based elastomer in an amount of 50 to 70 wt% and an ethylene-based elastomer in an amount of 10 to 30 wt% and a blowing agent residue, based on the total weight of the second layer.

5. The multilayer article of claim 3, wherein, the foam comprises: closed cells, or open cells, or a combination of closed cells and open cells.

6. The multilayer article of claim 3, wherein, the foam comprises closed cells.

7. The multilayer article of claim 3, further comprising: a third layer, wherein the third layer is between the second layer and the fourth layer.

8. The multilayer article of claim 7, wherein, the third layer has the same composition as the first layer.

9. The multilayer article of claim 7, wherein, the second layer has a greater thickness than the first layer and the third layer.

10. The multilayer article of claim 7, wherein, the first layer, the second layer, the third layer, and the fourth layer all comprise a melt processable thermoplastic polyolefin.

11. The multilayer article of claim 1, further comprising a crosslinked polypropylene layer and a thermoplastic substrate layer to form a rigid multilayer article; wherein, the crosslinked polypropylene layer is between the fourth layer and the thermoplastic substrate layer, the first layer is in contact with one face of the fourth layer, the one face being the face of the fourth layer opposite the face in contact with the crosslinked polypropylene layer.

12. The multilayer article of claim 7, further comprising a crosslinked polypropylene layer and a thermoplastic substrate layer to form a rigid multilayer article; wherein, the crosslinked polypropylene layer is between the fourth layer and the thermoplastic substrate layer, the third layer is in contact with one face of the fourth layer, the one face being the face of the fourth layer opposite the face in contact with the crosslinked polypropylene layer.

13. The multilayer article of claim 1, wherein, the fourth layer comprises a fabric or a film, and the fourth layer comprises a polypropylene homopolymer or copolymer.

14. The multilayer article of claim 11 or 12, wherein, the crosslinked polypropylene layer comprises a foam.

15. A method of making a multi-layer article, the method comprising: extruding a first layer, the first layer comprising a first thermoplastic polyolefin; unwinding a fourth layer from a feed roll, wherein the fourth layer comprises an olefin polymer having a peak melting point of 130°C to 170°C, the first layer having a lower modulus of elasticity than the fourth layer; and feeding the first layer and the fourth layer into a nip in a roll mill, laminating the first layer and the fourth layer in the nip to make a multi-layer article.

16. The method of claim 15, further comprising: co-extruding a second layer and a third layer and feeding the second layer and the third layer into the nip in the roll mill; wherein the second layer and the third layer both comprise a thermoplastic polyolefin, the first layer and the fourth layer are on outer surfaces of the second layer and the third layer, respectively, an inner surface of the second layer is in contact with an inner surface of the third layer.

17. The method according to claim 15, further comprising: adhering the multi-layer article to a crosslinked polypropylene layer and a thermoplastic substrate layer to form a rigid multi-layer article; wherein the crosslinked polypropylene layer is positioned between the fourth layer and the thermoplastic substrate layer, the first layer is in contact with one face of the fourth layer, the one face being the face of the fourth layer opposite the face in contact with the crosslinked polypropylene layer.

18. The method according to claim 16, further comprising: adhering the multi-layer article to a crosslinked polypropylene layer and a thermoplastic substrate layer to form a rigid multi-layer article; wherein the crosslinked polypropylene layer is positioned between the fourth layer and the thermoplastic substrate layer, the third layer is in contact with one face of the fourth layer, the one face being the face of the fourth layer opposite the face in contact with the crosslinked polypropylene layer.

19. A method of recycling a multi-layer article, the method comprising: comminuting a multi-layer article (A), the multi-layer article (A) comprising: c) a first layer comprising a first thermoplastic polyolefin; and d) a fourth layer comprising an olefin polymer having a peak melting point of 130 °C to 170 °C; or comminuting a multi-layer article (B), the multi-layer article (B) comprising: v) a first layer comprising a first thermoplastic polyolefin; vi) a second layer comprising a second thermoplastic polyolefin; vii) a third layer comprising a third thermoplastic polyolefin; and viii) a fourth layer comprising an olefin polymer having a peak melting point of 130 °C to 170 °C, wherein the first thermoplastic polyolefin is different from the second thermoplastic polyolefin; in a melt processing machine, melt blending the comminuted multi-layer article (A) corresponding powder or the comminuted multi-layer article (B) corresponding powder with additional thermoplastic polyolefin; wherein the powder made from comminuting the multi-layer article (A) and the multi-layer article (B) each comprises at least 50 wt% thermoplastic polyolefin.

20. The method according to claim 19, wherein, each of the multi-layer article (A) and the multi-layer article (B) further comprises a crosslinked polypropylene layer and a thermoplastic substrate layer.

Images