Method for producing composite molded article and composite molded article

Abstract

To provide a method for producing a composite molded article, which allows for an easy production of a molded article having excellent mechanical strength, and the composite molded article.SOLUTION: A method for producing a composite molded article according to the embodiment includes the steps of: preparing a raw material containing a polymer material including a crystalline polymer and an inorganic solid material; and compressing the raw material while heating it to a molding temperature below a melting point of the crystalline polymer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a method for manufacturing a composite compact and a composite compact. [Background technology]

[0002] Composite molded articles are known that are obtained by mixing a plastic material with a filler. Patent Document 1 describes a technique that uses wax as the base material so as not to impair the physical and mechanical properties of the polymer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-017905 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for a technique for easily producing a high-strength composite molding without using special additives as in Patent Document 1.

[0005] The problem to be solved by the present invention is to provide a method for producing a composite molded article, which allows for the easy production of a molded article having excellent mechanical strength, and the composite molded article. [Means for solving the problem]

[0006] The present inventors conceived the idea that excellent mechanical strength could be achieved in a composite molded product by combining an inorganic solid material with a polymer material. As a result of extensive research, the present inventors discovered that a composite molded product with excellent mechanical strength could be produced by compression molding at a molding temperature below the melting point of the crystalline polymer contained in the polymer material.

[0007] The present invention may include the following aspects. [1] A method for producing a composite molded body, comprising the steps of: preparing a raw material containing a polymer material including a crystalline polymer and an inorganic solid material; and compressing the raw material while heating it to a molding temperature below the melting point of the crystalline polymer. [2] The method according to [1], wherein the crystalline polymer is partially fluidized at the molding temperature. [3] The method according to [1] or [2], wherein the crystallinity of the crystalline polymer increases before and after the compressing step. [4] The method according to any one of [1] to [3], further comprising the step of pouring the raw material into a mold, wherein the compressing step comprises compressing the raw material in the mold at the molding temperature. [5] The method according to any one of [1] to [4], wherein at least one of the polymer material and the inorganic solid material comprises waste and / or a material derived from waste. [6] The method according to any one of [1] to [5], wherein the crystalline polymer comprises one or more selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyamide, polyacetal, polyoxymethylene, polyphenylene sulfide, polyether ether ketone, polytetrafluoroethylene, and cellulose. [7] The method according to any one of [1] to [6], wherein the inorganic solid material comprises at least one selected from the group consisting of silicon oxide, metal oxide, and metal sulfate. [8] The method according to any one of [1] to [7], wherein the inorganic solid material comprises one or more selected from the group consisting of fly ash, gypsum, and concrete. [9] The method according to any one of [1] to [8], wherein the composite molding contains 10 parts by mass or more and 99 parts by mass or less of the polymer material and 1 part by mass or more and 80 parts by mass or less of the inorganic solid material, with the entire composite molding being 100 parts by mass.

[10] The method according to any one of [1] to [9], further comprising the step of pulverizing at least a portion of the raw material before the step of compressing the raw material.

[11] A composite molded product comprising a polymer material containing a crystalline polymer and an inorganic solid material, wherein the crystalline polymer has a crystallinity of more than 50%.

[12] The composite molded body according to

[11] , wherein some of the carbon atoms contained in the composite molded body are bonded to semimetal atoms or metal atoms. [Effects of the Invention]

[0008] According to the present invention, a molded article having excellent mechanical strength can be easily produced. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a scanning electron microscope (SEM) image of the composite molded body obtained in Example 1-1. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes a manufacturing method of a composite molded body and a composite molded body according to an embodiment. Note that the following embodiment shows one aspect of the present invention, does not limit the present invention, and can be arbitrarily modified within the scope of the technical concept of the present invention. Furthermore, each configuration and each feature of the embodiment can be arbitrarily combined.

[0011] <1. Method for manufacturing composite molded body> The method for manufacturing a composite molded body according to this embodiment includes the steps of preparing a raw material containing a polymer material including a crystalline polymer and an inorganic solid material, and compressing the raw material while heating it to a temperature below the melting point of the crystalline polymer.

[0012] <1-1.Definition> In this specification, the term "composite molded body" refers to a molded body in which two or more materials with different chemical compositions (e.g., organic and inorganic materials) are molded together. The two or more materials may or may not be uniformly mixed.

[0013] As used herein, "polymer material" refers to an organic polymer material. "Natural polymer material" refers to an organic polymer material derived from natural products. "Synthetic polymer material" refers to an organic polymer material artificially synthesized. A polymer material may be a single type of organic polymer material that has a substantially common chemical composition, or a mixture of two or more types of organic polymer materials that have different chemical compositions.

[0014] "Organic polymer material" refers to an organic compound composed of one or more types of structural units repeatedly bonded together, and has a mass average molecular weight of 1,000 or more.

[0015] As used herein, the term "crystalline polymer" refers to a polymer that can form crystalline regions in its structure where molecules are regularly arranged.

[0016] In this specification, the term "inorganic solid material" refers to an inorganic material that is solid at room temperature and normal pressure.

[0017] In this specification, "thermal compression molding" means applying heat and pressure to an object to mold it into a predetermined shape.

[0018] In this specification, the term "major component" refers to a component that accounts for more than 50% by mass of the total.

[0019] <1-2. Raw materials> The above method uses a polymer material and an inorganic solid material as raw materials, and by mixing these raw materials and subjecting them to thermal compression molding, a composite molded product with excellent mechanical strength can be obtained.

[0020] The raw material may further contain materials other than the polymer material and the inorganic solid material. The total amount of the polymer material and the inorganic solid material contained in 100 parts by mass of the raw material may be, for example, 10 parts by mass to 100 parts by mass, 30 parts by mass to 99 parts by mass, 50 parts by mass to 98 parts by mass, 70 parts by mass to 97 parts by mass, 80 parts by mass to 96 parts by mass, or 90 parts by mass to 95 parts by mass. If the total amount of the polymer material and the inorganic solid material is less than 10 parts by mass, the improvement in mechanical strength due to the polymer material and the inorganic solid material may not be sufficiently achieved in the composite molded product.

[0021] The raw material may include waste. For example, one or both of the polymer material and the inorganic solid material may include waste or waste-derived materials. Preferably, both the polymer material and the inorganic solid material included in the raw material are waste or waste-derived materials. For example, the polymer material includes plastic waste and / or synthetic fiber waste. For example, the inorganic solid material includes industrial waste generated from facilities such as power plants, factories, construction sites, and laboratories.

[0022] By using waste-derived materials as raw materials, resources can be reused to produce excellent composite molded products. In particular, when both the polymer material and the inorganic solid material contained in the raw materials are obtained from waste, it is very preferable because excellent composite molded products can be produced by effectively utilizing both plastic waste, which is difficult to handle, and waste from the coal mining and construction industries, which produce large amounts of waste.

[0023] <1-2-1. Polymer materials> The polymer material itself contributes to the mechanical strength of the composite molded body, while also functioning as a matrix that supports the particles of the inorganic solid material. The amount of polymer material contained in 100 parts by mass of raw material may be, for example, 10 to 99 parts by mass, 15 to 90 parts by mass, 20 to 80 parts by mass, 25 to 50 parts by mass, or 30 to 40 parts by mass. If the amount of polymer material is 10 parts by mass or more, it can bind the inorganic solid material. If the amount of polymer material is 99 parts by mass or less, it can be expected that the inorganic solid material will improve strength.

[0024] The polymeric material includes one or both of synthetic polymeric materials and natural polymeric materials. Examples of synthetic polymeric materials include plastics, synthetic fibers, thermosetting resins, etc. Examples of natural polymeric materials include cotton, linen, etc.

[0025] The polymer material includes a crystalline polymer. The polymer material may also include a polymer other than a crystalline polymer. The amount of crystalline polymer contained in 100 parts by mass of the polymer material may be, for example, 10 parts by mass or more and 100 parts by mass or less, 50 parts by mass or more and 99 parts by mass or less, 70 parts by mass or more and 98 parts by mass or less, or 90 parts by mass or more and 95 parts by mass or less. If the content of the crystalline polymer is 10 parts by mass or more, the strength of the molded body can be expected to be improved by the crystalline portion.

[0026] Examples of crystalline polymers include one or more selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyamide, polyacetal, polyoxymethylene, polyphenylene sulfide, polyether ether ketone, polytetrafluoroethylene, and cellulose. However, crystalline polymers are not limited to these. Among the above examples of crystalline polymers, cellulose is an example of a natural polymer material, and the other materials are examples of synthetic polymer materials. The polyethylene may be one or more of high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE).

[0027] A crystalline polymer may contain crystalline regions in which molecules are regularly arranged within its structure. Crystalline polymers typically contain crystalline regions in which molecules are regularly arranged and amorphous regions in which molecules are irregularly distributed. The crystallinity of a crystalline polymer can be expressed by its degree of crystallinity. For example, a crystalline polymer may have a degree of crystallinity of 5% to 100%, 10% to 99%, 20% to 98%, 30% to 97%, 40% to 96%, 50% to 95%, 60% to 92%, 70% to 90%, or 80% to 85%. If the degree of crystallinity of a crystalline polymer is 5% or higher, the crystalline portion can be expected to improve the strength of the molded article.

[0028] The crystallinity of the crystalline polymer (hereinafter referred to as X c ) is the enthalpy of fusion of a crystalline polymer, ΔH, measured by differential scanning calorimetry (DSC). m However, the degree of crystallinity X can be calculated based on whether cold crystallization of crystalline polymers occurs in DSC measurements. c The calculation formula is different.

[0029] (1) When cold crystallization of crystalline polymers does not occur The melting enthalpy (measured value) of the crystalline polymer obtained by DSC measurement is expressed as ΔH m The literature value of the enthalpy of fusion of the crystalline polymer is ΔH m 0 If the mass % of materials other than the crystalline polymer in the measurement sample is w, the crystallinity of the crystalline polymer, X c can be calculated using the following relation:

number

[0030] (2) Cold crystallization of crystalline polymers occurs The melting enthalpy (measured value) of the crystalline polymer obtained by DSC measurement is expressed as ΔH m The cold crystallization enthalpy (measured value) of the crystalline polymer is ΔH cThe literature value of the enthalpy of fusion of the crystalline polymer is ΔH m 0 If the mass % of materials other than the crystalline polymer in the measurement sample is w, the crystallinity of the crystalline polymer, X c can be calculated using the following relation:

number

[0031] Examples of polymers other than crystalline polymers include polyvinyl chloride (PVC), polystyrene (PS), polymethyl methacrylate (PMMA), acrylonitrile butadiene styrene copolymer (ABS), polycarbonate (PC), modified polyphenylene ether (m-PPE), polyethersulfone (PESU), polyetherimide (PEI), polyamideimide (PAI), etc. The polymer material may contain one or more of these, or may contain polymers other than these.

[0032] <1-2-2. Inorganic solid materials> The inorganic solid material improves the mechanical strength of the composite molded body. For example, the inorganic solid material may be in the form of numerous inorganic particles. The amount of inorganic solid material contained in 100 parts by mass of raw material may be, for example, 1 part by mass to 80 parts by mass, 10 parts by mass to 75 parts by mass, 20 parts by mass to 70 parts by mass, 30 parts by mass to 65 parts by mass, or 50 parts by mass to 60 parts by mass. When the amount of inorganic solid material is 1 part by mass or more, a composite molded body with sufficient strength can be produced. When the amount of inorganic solid material is 80 parts by mass or less, the composite molded body can be prevented from becoming brittle and failing to solidify or crumbling.

[0033] The inorganic solid material may be, for example, an inorganic solid material that can function as a binder capable of binding particles of other materials together. Examples of inorganic solid materials that can function as binders include fly ash, gypsum, cement, ground granulated blast furnace slag, and sodium silicate.

[0034] The inorganic solid material may be, for example, an inorganic solid material for construction. Examples of the inorganic solid material for construction include fly ash, gypsum, concrete, cement, silica fume, blast furnace slag fine powder, sand, stone, gravel, etc.

[0035] The inorganic solid material may, for example, contain Si atoms. By bonding with the carbon atoms contained in the polymer material, the Si atoms can facilitate the formation of crystal nuclei, stabilize the crystals of the crystalline polymer, and may improve the crystallinity of the crystalline polymer. Also, locally formed SiC may improve the strength of the composite body. Among the above examples, fly ash, concrete, cement, silica fume, blast furnace slag fine powder, sand, stone, gravel, sodium silicate, etc. are Si-containing inorganic solid materials containing Si atoms.

[0036] The inorganic solid material may, for example, contain one or more selected from the group consisting of silicon oxide, metal oxides, and metal sulfates. The silicon oxide may be silicon dioxide, but is not limited thereto, and may be a silicon oxide SiOx (0 < x ≤ 2) in which silicon atoms and oxygen atoms are bonded in an arbitrary composition ratio. Examples of the metal oxides include aluminum oxide, iron oxide, calcium oxide, magnesium oxide, etc. Examples of the metal sulfates include calcium sulfate, barium sulfate, magnesium sulfate, aluminum sulfate, etc.

[0037] The inorganic solid material may, for example, contain one or more selected from the group consisting of fly ash, gypsum, and concrete.

[0038] Fly ash is a spherical, vitreous ash collected from combustion gases, a type of coal ash produced as a by-product at thermal power plants. The type of fly ash is not particularly limited and may be one or more of Type I, Type II, Type III, and Type IV. When the inorganic solid material contains fly ash, the amount of fly ash contained in 100 parts by mass of the inorganic solid material may be, for example, 10 parts by mass to 100 parts by mass, 50 parts by mass to 99 parts by mass, 80 parts by mass to 98 parts by mass, or 90 parts by mass to 95 parts by mass.

[0039] The gypsum is calcium sulfate hydrate or calcium sulfate anhydrite, or a material containing these as a main component. The hydration amount of the gypsum is not particularly limited, and examples of gypsum with different hydration amounts include gypsum dihydrate, gypsum hemihydrate, and anhydrous gypsum. Furthermore, the gypsum may not be pure calcium sulfate hydrate or calcium sulfate anhydrite, but may be natural gypsum or chemical gypsum (such as phosphate gypsum, flue gas desulfurization gypsum, titanic gypsum, refined gypsum, and hydrofluoric gypsum). When the inorganic solid material contains gypsum, the amount of gypsum contained in 100 parts by mass of the inorganic solid material may be, for example, 10 parts by mass to 100 parts by mass, 50 parts by mass to 99 parts by mass, 80 parts by mass to 98 parts by mass, or 90 parts by mass to 95 parts by mass.

[0040] Concrete is a material formed by mixing and hardening cement, coarse aggregate, fine aggregate, and water. Examples of cement include Portland cement, blast furnace slag powder, silica fume, and fly ash. Examples of coarse aggregate include natural gravel and blast furnace slag coarse aggregate. Examples of fine aggregate include natural sand and blast furnace slag. The amount of each component in concrete is not particularly limited. The concrete contained in the inorganic solid material may be concrete structures of any shape, or concrete in various forms, such as fragments, granules, or powder, resulting from crushing concrete structures. The concrete contained in the inorganic solid material may also be concrete waste. Examples of concrete waste include concrete rubble generated during the construction of structures such as buildings, roads, railways, and utility poles. When the inorganic solid material includes concrete, the amount of concrete contained in 100 parts by mass of the inorganic solid material may be, for example, 10 parts by mass or more and 100 parts by mass or less, 50 parts by mass or more and 99 parts by mass or less, 80 parts by mass or more and 98 parts by mass or less, or 90 parts by mass or more and 95 parts by mass or less.

[0041] <1-2-3. Crushing and mixing of raw materials> Each component of the raw material preferably has a size suitable for thermal compression molding. If the raw material is excessively large, it may be appropriately pulverized before mixing. That is, a step of pulverizing at least a portion of the raw material (e.g., one or both of the polymer material and the inorganic solid material) may be performed before the raw material is compressed. The pulverization method is not particularly limited, and any method such as pulverization, crushing, chemical decomposition, or classification can be used alone or in combination. The optimal size of the raw material depends on the material, molding conditions, and the application of the composite molded body. For example, the particle size of both the polymer material and the inorganic solid material may be 100 nm or more and 10 mm or less. The particle size distribution is also not particularly limited, as long as it has a particle size distribution suitable for molding. Note that the particle sizes of the polymer material and the inorganic solid material do not necessarily have to be uniform.

[0042] The components of the raw materials are mixed before molding. The method of mixing the raw materials is not particularly limited. The components may be mixed until they are homogeneous, or they may be subjected to molding in an inhomogeneous state without being sufficiently mixed. The mixing process of the raw materials may be omitted.

[0043] The mixing ratio of the polymer material and the inorganic solid material is not particularly limited. The amount of inorganic solid material added, based on 100 parts by mass of polymer material, may be, for example, 1 part by mass to 1000 parts by mass, 5 parts by mass to 500 parts by mass, 10 parts by mass to 300 parts by mass, 20 parts by mass to 200 parts by mass, 50 parts by mass to 150 parts by mass, or 70 parts by mass to 100 parts by mass. When the amount of inorganic solid material added is 1 part by mass or more, a composite molded product with sufficient strength can be produced. When the amount of inorganic solid material is 1000 parts by mass or less, the inorganic solid material can be bound by the polymer material.

[0044] <1-3. Thermal compression molding> The raw material is heated and compressed to form a desired shape. For example, in thermal compression molding, a predetermined molding pressure is applied to the raw material for a predetermined molding time while the raw material is maintained at a predetermined molding temperature. This compresses the raw material at a high temperature. The molding process can be carried out without heating the raw material above the melting point of the crystalline polymer.

[0045] <1-3-1. Molding method> There are no particular limitations on the specific molding method as long as it is possible to heat and compress the raw material. As non-limiting examples, the following techniques can be used. (1) Molding using a mold: The raw material is placed in a mold of a predetermined shape, heated to the molding temperature, and compressed within the mold. (2) Extrusion molding: Heated raw materials are extruded through a die (a mold with an extrusion opening) to form the raw materials into a desired shape. Since the raw materials are pressurized by the extrusion process, thermal compression molding can be performed. (3) Injection molding: The heated material is pressurized and injected into a mold, and then cooled to form the material into a desired shape. Since the material is pressurized by the injection operation into the mold, thermal compression molding can be performed. (4) Vacuum forming: The raw material is placed on a mold, a cover is placed on top of it, and a vacuum is drawn between the mold and the cover to compress the raw material. (5) Pressure molding: The raw material is placed on a mold and compressed by applying pressure from above with compressed air. (6) Autoclave molding: The raw material is heated and pressurized in an autoclave. The raw material may be autoclaved after each of the above treatments.

[0046] The molding method using the mold (1) above will be further explained below as an example. The shape, structure, size, and material of the mold are not particularly limited as long as the raw material can be molded into the desired shape. The mold has a mold frame that forms a space for introducing the raw material (hereinafter also referred to as the "molding space"). The molding space may be, for example, a recess defined by the mold frame. The mold may be a single structure or may be composed of two or more parts. The mold may be a so-called hot press device. The mold used for extrusion molding may have an extrusion port for extruding the raw material.

[0047] The raw material placed in the mold is heated to a molding temperature. The raw material is consolidated by being compressed in the mold and molded into a desired shape corresponding to the shape of the mold. The heat treatment may be carried out before, during, or after compression. The raw material may be placed in a preheated mold, or the raw material in contact with the mold may be heated by placing the raw material in the mold and then heating the mold. After the thermal compression, the mold is cooled and the molded body is released from the mold. The molded body may be cooled by natural cooling or may be cooled at a desired cooling rate by temperature control.

[0048] <1-3-2. Molding conditions> First, the molding temperature will be described. Here, the "molding temperature" refers to the temperature of the raw material during thermal compression molding.

[0049] Generally, crystalline polymers contain crystalline regions and amorphous regions. Below the glass transition temperature, neither the crystalline nor amorphous regions flow. Above the glass transition temperature and below the melting point, the crystalline regions do not substantially flow, while the amorphous regions flow. Above the melting point, the crystalline regions melt, and the entire crystalline polymer flows. Thus, the behavior of crystalline polymers during thermal compression molding changes depending on the relationship between the molding temperature and the glass transition temperature and melting point of the crystalline polymer.

[0050] The molding temperature is below the melting point of the crystalline polymer contained in the polymer material. Here, when the polymer material contains multiple types of crystalline polymers, the molding temperature is below the melting point of at least one type of crystalline polymer, and preferably below the melting points of all crystalline polymers contained in the polymer material. If molding is performed at a temperature below the melting point of the crystalline polymer, the crystalline regions of the crystalline polymer do not melt, and the strength derived from the crystalline regions of the crystalline polymer can be maintained in the resulting composite molded product.

[0051] The molding temperature is preferably equal to or higher than the glass transition temperature of the polymer contained in the polymer material. Here, when the polymer material contains multiple types of polymers, the molding temperature may be equal to or higher than the glass transition temperature of at least one type of polymer, and is preferably equal to or higher than the glass transition temperatures of all polymers contained in the polymer material. In such cases, the crystalline polymer partially fluidizes at the molding temperature. Specifically, the amorphous region of the crystalline polymer at least partially fluidizes at the molding temperature. If the molding temperature is set to a temperature equal to or higher than the glass transition temperature, the amorphous region of the polymer material fluidizes, bonding the particles of the inorganic solid material together, thereby improving the strength of the composite molded product.

[0052] The specific molding temperature can be appropriately determined depending on the application, and may be, for example, 40°C or higher and 300°C or lower, 50°C or higher and 250°C or lower, 60°C or higher and 200°C or lower, 70°C or higher and 150°C or lower, 80°C or higher and 140°C or lower, 90°C or higher and 130°C or lower, 95°C or higher and 125°C or lower, or 100°C or higher and 120°C or lower.

[0053] Next, the molding pressure will be described. The molding pressure can be appropriately determined depending on conditions such as the raw materials, molding temperature, and application. The molding pressure may be, for example, 1 MPa to 100 MPa, 10 MPa to 90 MPa, 15 MPa to 80 MPa, 20 MPa to 70 MPa, 25 MPa to 60 MPa, or 30 MPa to 50 MPa. If the molding pressure is 1 MPa or more, the shape of the composite compact after compression can be maintained. If the molding pressure is 100 MPa or less, molding failure due to excessive pressure can be suppressed.

[0054] Next, the molding time will be described. The molding time can be appropriately determined depending on conditions such as the raw material, molding temperature, molding pressure, and application. The molding time may be, for example, from 10 seconds to 1 hour, from 20 seconds to 50 minutes, from 30 seconds to 40 minutes, from 1 minute to 30 minutes, from 5 minutes to 25 minutes, or from 10 minutes to 20 minutes.

[0055] The atmosphere in the molding space where the thermal compression molding is performed is not particularly limited. For example, the thermal compression molding may be performed in the atmosphere, in a reduced pressure environment, or in an environment replaced with any atmospheric gas such as an inert gas.

[0056] Preferably, the crystallinity of the crystalline polymer increases before and after the thermal compression molding step. For example, the crystallinity of the crystalline polymer increases by 0.1% or more, 1% or more, 5% or more, or 10% or more before and after the thermal compression molding step. Here, when the polymer material contains multiple types of crystalline polymers, the crystallinity of at least one type of crystalline polymer contained in the polymer material increases before and after the compression molding step. Preferably, the crystallinity of all crystalline polymers contained in the polymer material increases before and after the compression molding step.

[0057] <1-4. Presumed mechanism of strength improvement> By carrying out thermal compression molding under the above conditions, a composite molded product with excellent mechanical strength can be obtained. Here, "excellent mechanical strength" means that at least one of compressive strength, bending strength, and tensile strength is greater than that of a molded product obtained by molding the raw material polymer material or inorganic solid material alone under the same molding conditions (molding temperature, molding pressure, and molding time).

[0058] As shown in the examples below, the present inventors have discovered that a composite molded body with excellent mechanical strength can be obtained by subjecting a raw material mixture of a crystalline polymer and an inorganic solid material to thermal compression molding at a molding temperature below the melting point of the crystalline polymer. The obtained composite molded body had superior mechanical strength (e.g., compressive strength) to a molded body obtained by molding the crystalline polymer alone. The obtained composite molded body had superior bonding strength between the constituent materials to a molded body obtained by molding the inorganic solid material alone, and had the ability to maintain the shape of the molded body. Although not intended to be restrictive of the present invention, the present inventors speculate that the following mechanism is the reason why such a composite molded body was obtained.

[0059] In general, inorganic solid materials have superior mechanical strength to crystalline polymers. This is due to the fact that the atoms of the inorganic solid material bond together via ionic bonds to form a dense crystalline structure, resulting in high structural strength and density. However, even when the inorganic solid material is heated at temperatures as low as the melting point of the crystalline polymer, the individual particles do not fuse together. Therefore, even when the inorganic solid material is subjected to thermal compression molding alone, the particles do not bond well together, making it difficult to maintain the shape of the molded product. In contrast, organic polymer materials can function as binders that bind the particles of the inorganic solid material together. In particular, when the amorphous region fluidizes above the glass transition temperature, the polymer can efficiently penetrate between the particles of the inorganic solid material during thermal compression molding, bonding them together. Therefore, by mixing a polymer and an inorganic solid material and then performing thermal compression molding, the particles of the inorganic solid material, which has excellent mechanical strength, can be bonded together, and the mechanical strength of the inorganic solid material can be reflected in the final composite molded product.

[0060] Furthermore, by using a crystalline polymer and molding it while heating below the melting point of the crystalline polymer, it is possible to bond the particles of the inorganic solid material together in the amorphous regions while maintaining the mechanical strength of the crystalline regions. If the composite were heated at a temperature above the melting point of the crystalline polymer, the crystalline regions would also melt, and the crystallinity of the crystalline polymer in the composite would likely decrease compared to before molding. However, by setting the molding temperature at a level that does not melt the crystalline regions, it is possible to maintain the crystallinity of the crystalline polymer without any decrease before and after molding. Therefore, the final composite can have excellent mechanical strength derived from both the inorganic solid material and the crystalline regions of the crystalline polymer.

[0061] Furthermore, as described below, examples were also confirmed in which the crystallinity of the crystalline polymer increased before and after thermal compression molding. Although the mechanism behind this increase in crystallinity is not fully understood, the following mechanism is hypothesized. During thermal compression molding, when metalloid or metal atoms such as Si or Ca contained in the inorganic solid material bond to carbon atoms in the crystalline polymer (e.g., carbon atoms near the end of a linear polymer), the formation of crystal nuclei is facilitated and the crystals of the crystalline polymer are stabilized. This may improve the crystallinity of the crystalline polymer. Furthermore, compounds obtained by bonding metalloid or metal atoms to carbon atoms often have high strength and toughness, so these compounds may also improve the strength of the composite molded product. However, an increase in crystallinity is not an essential condition for the present invention.

[0062] <2. Composite molded body> The composite molded product according to this embodiment is a composite molded product containing a polymer material containing a crystalline polymer and an inorganic solid material, in which the crystallinity of the crystalline polymer is greater than 50%.

[0063] The composite molded article can be used for any purpose, for example, as a material for building materials, architecture, furniture, carpets, containers, interior goods, tableware, decorative items, and the like.

[0064] <2-1. Components of the composite molding> The composite molded body contains the above-mentioned polymer material and inorganic solid material. As mentioned above, other materials may also be contained. The amount of polymer material contained in 100 parts by mass of the composite molded body may be, for example, 10 parts by mass or more and 99 parts by mass or less, 15 parts by mass or more and 90 parts by mass or less, 20 parts by mass or more and 80 parts by mass or less, 25 parts by mass or more and 50 parts by mass or less, or 30 parts by mass or more and 40 parts by mass or less. When the amount of polymer material is 10 parts by mass or more, the inorganic solid material in the composite molded body can be sufficiently bound. When the amount of polymer material is 99 parts by mass or less, the composite molded body can have sufficient strength.

[0065] The amount of crystalline polymer contained in 100 parts by weight of the polymer material may be, for example, 10 parts by weight or more and 100 parts by weight or less, 50 parts by weight or more and 99 parts by weight or less, 70 parts by weight or more and 98 parts by weight or less, or 90 parts by weight or more and 95 parts by weight or less. As described above, the crystallinity of the crystalline polymer may be greater than 50%, for example, 55% or more, 60% or more, 65% or more, 70% or more, 75% or more, 78% or more, 80% or more, 82% or more, 85% or more, 87% or more, or 90% or more. When the crystallinity of the crystalline polymer is greater than 50%, the crystalline regions of the crystalline polymer can sufficiently improve the mechanical strength of the composite molded product.

[0066] The amount of inorganic solid material contained in 100 parts by mass of the composite molded body may be, for example, 1 part by mass or more and 80 parts by mass or less, 10 parts by mass or more and 75 parts by mass or less, 20 parts by mass or more and 70 parts by mass or less, 30 parts by mass or more and 65 parts by mass or less, or 50 parts by mass or more and 60 parts by mass or less. If the amount of inorganic solid material is 1 part by mass or more, the composite molded body can have sufficient strength. If the amount of inorganic solid material is 80 parts by mass or less, the composite molded body can be prevented from becoming brittle and not solidifying or collapsing.

[0067] Based on 100 parts by mass of polymer material, the amount of inorganic solid material contained in the composite molding may be, for example, 1 part by mass or more and 1000 parts by mass or less, 5 parts by mass or more and 500 parts by mass or less, 10 parts by mass or more and 300 parts by mass or less, 20 parts by mass or more and 200 parts by mass or less, 50 parts by mass or more and 150 parts by mass or less, or 70 parts by mass or more and 100 parts by mass or less.

[0068] Preferably, some of the carbon atoms in the composite compact are bonded to metalloid or metal atoms. Such interatomic bonds can improve the crystallinity of the crystalline polymer. Furthermore, the formation of high-strength metalloid carbides (e.g., SiC) or metal carbides (e.g., CaC) in the composite compact can improve the mechanical strength of the composite compact.

[0069] For example, the infrared absorption spectrum of the composite molding is -1absorption bands around (for example, 793 cm -1 ~795cm -1 This peak suggests that bonding between carbon atoms and silicon atoms (Si-C bonds) occurs in the composite compact.

[0070] <2-2. Physical properties of composite moldings> The composite molded article is molded to have various properties such as strength, rigidity, hardness, water resistance, heat resistance, etc. depending on the application. The molded article has properties suitable for construction applications, for example.

[0071] The compressive strength of the composite compact may preferably be 10 MPa or more, 15 MPa or more, 20 MPa or more, 22.5 MPa or more, 25 MPa or more, 27.5 MPa or more, or 30 MPa or more.

[0072] The flexural strength of the composite compact may preferably be 10 MPa or more, 12 MPa or more, 14 MPa or more, 15 MPa or more, 16 MPa or more, 18 MPa or more, 20 MPa or more, 22 MPa or more, 23 MPa or more, or 24 MPa or more.

[0073] The tensile strength of the composite compact may preferably be 5 MPa or more, 7 MPa or more, 9 MPa or more, 10 MPa or more, or 11 MPa or more.

[0074] <3. Effects> According to the above-described manufacturing method of a composite molded body and the composite molded body, a polymer material containing a crystalline polymer and an inorganic solid material are thermally compressed at a molding temperature below the melting point of the crystalline polymer, thereby maintaining a relatively high crystallinity of the crystalline polymer and obtaining a composite molded body with excellent mechanical strength. In addition to being able to produce a high-strength molded body using a relatively simple method, molding at a temperature below the melting point of the crystalline polymer naturally results in low-temperature molding, which significantly reduces molding costs. [Example]

[0075] The present invention will be described below with reference to experimental examples, but the present invention is not limited to the following experimental examples.

[0076] <Example 1-1> The following materials were prepared as raw polymer materials and inorganic solid materials. Polymer material: Powdered high-density polyethylene (HDPE) (manufactured by Featherfield Corporation) (median diameter: 70-80 μm, specific gravity: 0.907 g / cm 3 ) Inorganic solid material: Type II fly ash (FA) according to JIS standards (median diameter: 10-20 μm, specific gravity: 1.950 g / cm 3 )

[0077] The raw materials, HDPE and FA, were mixed at a mass ratio of 10:1. Mixing was carried out for 5 minutes using a mixer (37 rpm). The raw material mixture was then packed into a mold and subjected to thermal compression at a molding temperature of 75°C and a pressure of 40 MPa for 5 minutes. The molded body was then removed from the mold. In this way, an HDPE / FA composite molded body was obtained. The molding temperature and molding pressure were determined so as to obtain a composite molded body with excellent mechanical strength at a given mass ratio (the same applies to the following experimental examples).

[0078] <Example 1-2> A composite molded body of HDPE / FA was obtained in the same manner as in Example 1-1, except that the mixing ratio of the raw materials HDPE and FA was 3:1 by mass, the molding temperature was 100°C, and the pressure was 50 MPa.

[0079] <Examples 1-3> A composite molded body of HDPE / FA was obtained in the same manner as in Example 1-1, except that the mixing ratio of the raw materials HDPE and FA was 1:2 by mass, the molding temperature was 125°C, and the pressure was 50 MPa.

[0080] <Example 2> Gypsum was prepared by crushing gypsum board and sieving it through a sieve with a mesh opening of approximately 300 μm (hence, the particle size was 300 μm or less). Except for using this gypsum instead of FA as the inorganic solid material, a composite molded product of HDPE / gypsum was obtained in the same manner as in Example 1-3.

[0081] <Example 3-1> A PET / FA composite molding was obtained in the same manner as in Example 1-1, except that instead of HDPE, synthetic fiber particles made from crushed discarded clothing were used as the polymer material (the mixing ratio of synthetic fiber particles to FA was 10:1 by mass), and the molding temperature was 250°C and the pressure was 40 MPa. The clothing was crushed using a rotary cutter (RC250, Yoshiko Co., Ltd.). An examination of the composition of the crushed synthetic fiber particles revealed that the majority was polyethylene terephthalate (PET), with small amounts of acrylic fiber, rayon, and polyurethane. Hereinafter, the synthetic fiber particles will also be referred to as "PET."

[0082] <Example 3-2> A composite molded product of PET / FA was obtained in the same manner as in Example 3-1, except that the mixing ratio of PET and FA was 1:1 by mass and the molding pressure was 60 MPa.

[0083] Example 4-1 A composite molded body of cotton / PET / concrete was obtained in the same manner as in Example 1-1, except that, instead of HDPE, a mixture of cotton particles made from crushed discarded clothing (100% cotton) and synthetic fiber particles (the same as in Example 3-1) made from crushed discarded clothing was used as the polymer material, and crushed concrete was used instead of FA as the inorganic solid material (the mixing ratio of cotton particles, synthetic fiber particles, and concrete was 1:1:2 by mass), and the molding temperature was 220°C, the pressure was 20 MPa, and the pressure application time was 3 minutes.

[0084] <Example 4-2> A composite molded body of cotton / PET / concrete was obtained in the same manner as in Example 4-1, except that the mixing ratio of cotton particles, synthetic fiber particles (PET), and concrete was set to a mass ratio of 3:7:10.

[0085] <Example 4-3> A cotton / PET / concrete composite molding was obtained in the same manner as in Example 4-1, except that the mixing ratio of cotton particles, synthetic fiber particles (PET), and concrete was 1:1:1 by mass, the molding temperature was 250°C, and the pressure was 5 MPa.

[0086] <Comparative Example 1> An HDPE molded article was obtained in the same manner as in Example 1-1, except that FA was not mixed and only HDPE was used as the raw material.

[0087] <Comparative Example 2> A PET molded article was obtained in the same manner as in Example 3-1, except that FA was not mixed and only PET was used as a raw material.

[0088] <Comparative Example 3> An attempt was made to mold a molded body in the same manner as in Example 1-1, except that HDPE was not mixed and only FA was used as a raw material. However, when molding was attempted, the product did not solidify and crumbled, and molding failed.

[0089] <Comparative Example 4> Except for using only gypsum as a raw material without adding HDPE, an attempt was made to mold a molded body in the same manner as in Example 2. As a result, loose solidification in layers was confirmed, but the obtained molded body was brittle.

[0090] <Comparative Example 5> An attempt was made to mold an HDPE / FA composite in the same manner as in Example 1-1, except that the mixing ratio of the raw materials HDPE and FA was 1:1 by mass and the temperature was 200°C (a temperature higher than the melting point of HDPE). However, the material leaked out of the mold gap, and the molding failed.

[0091] <Comparative Example 6> A cotton / PET composite molding was obtained in the same manner as in Example 4-1, except that no concrete was mixed in, and only cotton particles and synthetic fiber particles (PET) were used as raw materials (the mixing ratio of cotton particles to synthetic fiber particles was 1:1 by mass), and the molding pressure was 5 MPa.

[0092] <Evaluation Example 1: Observation of Microstructure with a Scanning Electron Microscope (SEM)> Figure 1 shows an SEM image of the composite molded body obtained in Example 1-1, which was observed using an SEM. As shown in Figure 1, it was confirmed that the composite molded body had a microstructure in which FA particles (spherical particles in Figure 1) were dispersed in the HDPE matrix. This suggests that a strong physical bond was formed between the HDPE and FA.

[0093] <Evaluation Example 2: Mechanical Strength> To evaluate the mechanical strength of the composite compacts, the compressive strength, bending strength, and tensile strength were measured. The size of the test specimen for measuring compressive strength was approximately 10 mm in length, approximately 10 mm in width, and approximately 20 mm in height, in accordance with the standard of ASTM D695. The size of the test specimen for measuring flexural strength was approximately 50 mm x approximately 25 mm, in accordance with the standard of ASTM D790. The test specimen for measuring tensile strength was prepared in accordance with the Type IV standard specified in ASTM D638. Three test specimens were prepared for each of compressive strength, flexural strength, and tensile strength, and measurements were performed three times. However, in Examples 3-1, 3-2, 4-1 to 4-3, and Comparative Example 6, only the flexural strength test was performed.

[0094] The compressive strength, flexural strength, and tensile strength were all measured at room temperature (25±2°C) at a loading rate of 5 mm / min. The time when the first crack appeared in the sample was taken as the maximum load that the sample could withstand.

[0095] <Evaluation Example 3: Differential Scanning Calorimeter (DSC) Measurement> In order to evaluate the thermal properties and crystallinity of the composite molded bodies, measurements and analyses were carried out using a differential scanning calorimeter for Examples 1-1 to 1-3, Example 2, Example 3-1, Example 3-2, Comparative Example 1, and Comparative Example 2. Specifically, a portion (3 mg to 10 mg) of the compact was placed in an aluminum crucible, and the temperature was changed at a rate of 10°C / min to perform DSC measurement. The temperature was raised to 200°C for Examples 1-1 to 1-3 and Comparative Example 1, to 300°C for Example 2, and to 400°C for Examples 3-1, 3-2, and Comparative Example 2.

[0096] In Examples 1-1 to 1-3, Example 2, and Comparative Example 1, the melting temperature T m The enthalpy of fusion of HDPE, ΔH, is calculated from the peak area. m The enthalpy of fusion of the raw material HDPE, ΔH m 0 = 293 J / g, and the crystallinity of HDPE X c was calculated.

[0097] In Examples 3-1 and 3-2 and Comparative Example 2, the cold crystallization temperature T c and melting temperature T m The cold crystallization enthalpy ΔH c and enthalpy of fusion ΔH m The melting enthalpy of the raw material PET, ΔH m 0 = 362.74 J / g, and the crystallinity of PET X c was calculated.

[0098] The crystallinity (before thermal compression) of the HDPE and PET used as raw materials was 82% and 57%, respectively.

[0099] The raw materials, molding conditions, and evaluation results for each experimental example are summarized in Table 1. Here, HDPE is simply referred to as PE. [Table 1]

[0100] <Evaluation Example 4: Infrared Spectroscopic Measurement> In order to investigate the interaction between carbon and other elements in the composite compact, infrared spectroscopy was carried out for Examples 1-1 to 1-3. -1 A peak attributed to the Si-C bond was confirmed in the absorption band around 1000 MHz. In the molded bodies obtained in these examples, the bonding of Si to C facilitates the formation of crystal nuclei and facilitates the stabilization of the crystals of the crystalline polymer, which is presumably improving the crystallinity of the DHPE. Furthermore, since SiC is a material with high strength and toughness, it is presumed that the locally formed SiC improves the strength of the molded body.

Claims

1. providing a raw material including a polymeric material including a crystalline polymer and an inorganic solid material; compressing the raw material while heated to a molding temperature below the melting point of the crystalline polymer; A method for producing a composite molded body, comprising:

2. At the molding temperature, the crystalline polymer partially fluidizes. The method of claim 1.

3. The crystallinity of the crystalline polymer increases before and after the compressing step. The method according to claim 1 or 2.

4. further comprising the step of pouring the ingredients into a mold; the compressing step includes compressing the feedstock in the mold at the molding temperature; The method according to claim 1 or 2.

5. At least one of the polymeric material and the inorganic solid material comprises waste and / or waste-derived material; The method according to claim 1 or 2.

6. The crystalline polymer includes one or more selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyamide, polyacetal, polyoxymethylene, polyphenylene sulfide, polyether ether ketone, polytetrafluoroethylene, and cellulose; The method according to claim 1 or 2.

7. The inorganic solid material includes one or more selected from the group consisting of silicon oxide, metal oxide, and metal sulfate. The method according to claim 1 or 2.

8. The inorganic solid material includes one or more selected from the group consisting of fly ash, gypsum, and concrete; The method according to claim 1 or 2.

9. The composite molded body includes, with the entire composite molded body being 100 parts by mass, 10 parts by mass or more and 99 parts by mass or less of the polymer material and 1 part by mass or more and 80 parts by mass or less of the inorganic solid material. The method according to claim 1 or 2.

10. further comprising the step of comminuted at least a portion of the feedstock prior to compressing the feedstock. The method according to claim 1 or 2.

11. A composite molded body including a polymer material including a crystalline polymer and an inorganic solid material, A composite molded article, wherein the crystalline polymer has a crystallinity of more than 50%.

12. The composite compact according to claim 11, wherein some of the carbon atoms contained in the composite compact are bonded to metalloid atoms or metal atoms.

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