Resin processed raw material and method for producing the same

Abstract

To provide a resin processed raw material that enables the formation of a resin processed product having excellent processing accuracy as well as excellent strength and toughness by securing suitable fluidity during molding of the resin processed product.SOLUTION: A resin processed raw material includes type II anhydrous gypsum powder and a thermoplastic resin, where the type II anhydrous gypsum powder is contained by 55 mass% or more and 65 mass% or less based on the total mass of the resin processed raw material, the thermoplastic resin is contained by 35 mass% or more and 45 mass% or less based on the total mass of the resin processed raw material, and the particle size distribution of the type II anhydrous gypsum powder shows that 80% or more of particles are 10 μm or less.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a raw material for a resin processed product containing type II anhydrous gypsum and a method for producing the same. [Background technology]

[0002] Gypsum board is a very useful building material and is widely used in various buildings. However, the amount of waste gypsum board generated during, for example, the demolition of a building is enormous, and is expected to increase in the future.

[0003] Waste gypsum boards can be recycled; specifically, the gypsum and paper extracted from waste gypsum boards can be recycled as recyclable resources. When recycling, currently, for example, most of the gypsum extracted from waste gypsum boards is used to remanufacture gypsum boards or as a solidification material for sludge, etc. However, the amount of recycled waste gypsum boards is very small compared to the total amount of waste gypsum boards generated. In reality, most waste gypsum boards are landfilled. In other words, it cannot be said that the improvement and spread of the recycling environment for waste gypsum boards is progressing as desired.

[0004] Currently, waste gypsum boards are landfilled at controlled industrial waste disposal sites. However, there is a limit to the amount of land available for such sites, and in order to reduce environmental impact and health hazards, it is desirable to avoid such operations as much as possible.

[0005] For these reasons, it is desirable to realize an environment in which as much waste gypsum board as possible can be recycled. For these reasons, various techniques for processing waste gypsum board have been proposed, and are disclosed in, for example, Patent Documents 1 to 4. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2023-36207 A [Patent Document 2] JP 2023-36205 A [Patent Document 3] JP 2022-24689 A [Patent Document 4] Patent No. 6088277 Summary of the Invention [Problem to be solved by the invention]

[0007] The present inventors believe that the reasons why the improvement and widespread adoption of the recycling environment for waste gypsum boards has not progressed as desired are the following (1) to (4). (1) The main uses of the gypsum extracted from waste gypsum boards (remanufacturing gypsum boards and solidification material) are currently very limited. In other words, the market is limited, and many companies are reluctant to enter the market. (2) The gypsum extracted from waste gypsum boards is generally required to be in the form of gypsum dihydrate and needle-shaped crystals. In other words, these characteristics and properties place restrictions on the uses for recycling, making it difficult to expand the market (uses). (3) The gypsum extracted from the current waste gypsum board still contains a certain amount of foreign matter, such as sand and plastic, which can cause undesirable effects, for example, on the environmental front, limiting its uses. (4) Recycling waste gypsum board requires a lot of cost and effort, which acts as a barrier to entry.

[0008] The present inventors conducted intensive research in light of the above circumstances and discovered that by improving the properties of the gypsum extracted from waste gypsum boards and the manufacturing process, its uses could be expanded.

[0009] Specifically, the inventors have discovered that by converting the gypsum extracted from waste gypsum boards into fine anhydrous gypsum, particularly type II anhydrous gypsum, and by properly removing impurities, the uses of the gypsum extracted from waste gypsum boards can be significantly expanded.

[0010] More specifically, high-purity, fine anhydrous gypsum type II can be used, for example, as a raw material for resin processed products that are environmentally friendly and have excellent processing accuracy. Such gypsum-containing raw materials for resin processed products have no or few impurities, and are therefore expected to be used in the consumer sector.

[0011] The inventors of the present invention considered that it would be beneficial to produce a resin processed raw material by mixing type II anhydrous gypsum with a thermoplastic resin in order to make the resin processed raw material usable in various molding processes (mold processing) and to expand its applications. A resin processed product formed from such a resin processed raw material has the advantage that the strength can be improved by type II anhydrous gypsum compared to a processed product made only of a thermoplastic resin, for example. Above all, the use of recycled materials is of great significance in the current situation where environmental problems are becoming more serious.

[0012] However, since type II anhydrous gypsum does not change shape even when heated to a temperature at which the thermoplastic resin melts, it impairs the fluidity of the thermoplastic resin during molding, and depending on the content of type II anhydrous gypsum, proper processing cannot be performed. In addition, type II anhydrous gypsum causes roughness on the surface of the processed product, which may limit its use. In addition, depending on the content of type II anhydrous gypsum, although the strength is good, the toughness may be poor, which may limit its use.

[0013] On the other hand, the problem of fluidity during molding can be solved by reducing the content of type II anhydrite, but the strength of the finished processed product will decrease, and the significance of using recycled materials will be lost, and the appeal of environmental issues will be lost.

[0014] From the above viewpoints, the present inventors have conducted extensive research into a raw material for a resin processed product containing type II anhydrous gypsum and a thermoplastic resin, which can obtain the advantage of improving the strength of a molded product by type II anhydrous gypsum while suppressing a decrease in toughness and ensuring suitable fluidity during molding.

[0015] The present invention has been devised against the above background, and aims to provide a raw material for a resin processed product, which can ensure suitable fluidity during molding of the resin processed product, thereby achieving good processing precision, and which can form a resin processed product that has good strength and toughness, and a method for manufacturing the same. [Means for solving the problem]

[0016] The present invention relates to the following [1] and [2].

[0017] [1] A resin processed raw material containing type II anhydrous gypsum powder and a thermoplastic resin, The amount of the II-type anhydrous gypsum powder is 55% by mass or more and 65% by mass or less based on the total mass of the resin processed raw material, The thermoplastic resin is contained in an amount of 35% by mass or more and 45% by mass or less based on the total mass of the resin processed raw material, The type II anhydrous gypsum powder is a raw material for resin processed products, in which 80% or more of the components in the particle size distribution have a particle size of 10 μm or less.

[0018] [2] A first crushing process in which a waste gypsum board including a gypsum core material and paper attached to the gypsum core material is crushed, and an intermediate gypsum powder obtained by crushing the gypsum core material is separated from the paper; A heating step of heating the intermediate gypsum powder to convert it into type II anhydrous gypsum and burning off residues including paper and / or plastic contained in the intermediate gypsum powder; A second crushing step of crushing the intermediate gypsum powder after the heating step into fine gypsum powder; A raw material preparation process for preparing a resin processed raw material by mixing the fine gypsum powder as type II anhydrous gypsum powder with a thermoplastic resin, The type II anhydrous gypsum powder has a particle size distribution in which 80% or more of the components have a particle size of 10 μm or less, In the raw material preparation process, the type II anhydrous gypsum powder and the thermoplastic resin are mixed so that the type II anhydrous gypsum powder is contained in an amount of 55 mass% or more and 65 mass% or less relative to the total mass of the resin processed raw material, and the thermoplastic resin is contained in an amount of 35 mass% or more and 45 mass% or less relative to the total mass of the resin processed raw material. This is a manufacturing method for a resin processed raw material using waste gypsum board. Effect of the Invention

[0019] According to the present invention, it is possible to obtain a resin processed product having good processing accuracy and good strength and toughness by ensuring suitable fluidity during molding. [Brief description of the drawings]

[0020] [Figure 1] 1 is a diagram showing a schematic configuration of an example of a system used for producing a raw material for a resin processed product according to the present invention. FIG. [Diagram 2] 2 is a flowchart showing a procedure for producing a raw material for a resin processed product by the system shown in FIG. 1. [Diagram 3] FIG. 2 is a diagram showing an SEM image of an example of type II anhydrous gypsum powder used as a raw material for a resin processed product according to the present invention. [Figure 4] FIG. 2 is a graph showing an example of particle size distribution of type II anhydrous gypsum powder used as a raw material for a resin processed product according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] An embodiment of the present invention will now be described.

[0022] <Raw materials for resin processed products> The resin processed raw material according to one embodiment of the present invention is a resin processed raw material containing anhydrous gypsum powder of type II and a thermoplastic resin. More specifically, the resin processed raw material according to this embodiment contains anhydrous gypsum powder of type II with respect to its total mass in an amount of 55% by mass to 65% by mass, and a thermoplastic resin of 35% by mass to 45% by mass, relative to its total mass. The anhydrous gypsum powder contained in the resin processed raw material has a particle size distribution in which 80% or more of the components have a particle size of 10 μm or less.

[0023] The specific gravity of the II-type anhydrous gypsum powder is generally 2.97 g / cm3, and the specific gravity of the thermoplastic resin is generally 0.9 to 1.0 g / cm3. In this case, by making the content of the II-type anhydrous gypsum powder 55% by mass or more and 65% by mass or less, and making the content of the thermoplastic resin 35% by mass or more and 45% by mass or less, the ratio of the volume of the II-type anhydrous gypsum powder to the volume of the thermoplastic resin is approximately 1:2. In this case, when the thermoplastic resin is melted and mixed with the II-type anhydrous gypsum powder, each particle of the II-type anhydrous gypsum powder can be coated with a thickness of about half the particle diameter. Furthermore, the II-type anhydrous gypsum powder is one in which the particle diameter of 80% or more of the components in the particle diameter distribution is 10 μm or less, so that the II-type anhydrous gypsum powder is easily dispersed in the thermoplastic resin, and a coating state of the II-type anhydrous gypsum powder by the thermoplastic resin is easily formed. This makes it possible to suitably form a sea-island structure in which the thermoplastic resin forms a sea phase and the anhydrous gypsum powder forms an island phase when the anhydrous gypsum powder is mixed with the thermoplastic resin.

[0024] As a result, the resin processed product raw material according to the present embodiment can ensure suitable fluidity during molding of the resin processed product. This can improve the processing accuracy of the resin processed product. In addition, since more than half of the components in the resin processed product raw material by mass ratio are hard type II anhydrous gypsum powder, the strength of the resin processed product can be ensured, while the thermoplastic resin is also contained sufficiently, the toughness of the resin processed product can be ensured. Furthermore, since the particle diameter of many components in the type II anhydrous gypsum powder is 10 μm or less, the roughness of the surface of the completed resin processed product is suppressed, and there are also advantages such as easing the restrictions on the use of the resin processed product. Below, each component of the resin processed product raw material and components that can be selectively added will be described in detail.

[0025] (Type II anhydrite powder) As described above, the type II anhydrous gypsum powder contained in the resin processed material is one in which 80% or more of the components have a particle size of 10 μm or less in the particle size distribution. The particle size distribution of the type II anhydrous gypsum powder is a value measured using a laser diffraction / scattering particle size distribution measuring device (Microtrack MT3300EXII manufactured by Microtrack Bell Co., Ltd.). As specific measurement conditions, isopropyl alcohol (refractive index 1.38) is selected as the solvent, 1.81 is selected as the particle condition, transmission is selected as the particle transmittance, and non-spherical is selected as the particle shape.

[0026] In addition, the type II anhydrous gypsum powder used in this embodiment is non-needle crystalline and non-plate crystalline. Gypsum is generally a needle crystalline body, and by utilizing this characteristic, it exhibits advantages such as improving the bonding strength with other members. However, the type II anhydrous gypsum powder used in this embodiment is intentionally made to be non-needle crystalline and non-plate crystalline, which can suppress adverse effects on the fluidity during molding. The non-needle crystalline and non-plate crystalline state can be obtained by finely grinding the type II anhydrous gypsum powder.

[0027] Further, the type II anhydrous gypsum powder is one in which the type II anhydrous gypsum component is 90 mass% or more relative to the total. A state in which the type II anhydrous gypsum component is 90 mass% or more in the type II anhydrous gypsum powder means that the total value (mass%) of the Ca component and the S component in the type II anhydrous gypsum powder is 90 mass% or more. The mass ratio of the type II anhydrous gypsum component in the type II anhydrous gypsum powder is specified by determining the Ca component and the S component by wavelength dispersive X-ray fluorescence analysis and adding them up.

[0028] In this embodiment, it is assumed that the above-mentioned type II anhydrous gypsum powder is obtained from waste gypsum board. As a result, the resin processed product raw material is mostly made of recycled materials, and the appeal to environmental issues can be secured. However, the type II anhydrous gypsum powder does not have to be obtained from waste gypsum board.

[0029] (thermoplastic resin) The thermoplastic resin constituting the raw material of the resin processed product includes, for example, one or more of polypropylene, polyethylene, polystyrene, polyvinyl chloride, polyacetal, polyamide, polyethylene terephthalate, polycarbonate, polyphenylene sulfide, polyamideimide, and polyether ether ketone. However, thermoplastic resins other than those exemplified here may also be used.

[0030] As the thermoplastic resin, preferably, one having a melt flow rate (MFR) of 4g / 10 minutes or more and 6g / 10 minutes or less, measured according to JIS K 7210-1:2014 at a temperature of 230°C and a load of 2.16 kg, is used. With such an MFR, it is possible to ensure suitable fluidity during molding, and to ensure high strength and toughness in the resin processed product after molding. The higher the MFR of the thermoplastic resin, the higher the fluidity of the material during molding, while the smaller the molecular weight generally tends to result in a decrease in strength and toughness in the resin processed product after molding. Although an MFR of 4g / 10 minutes or more and 6g / 10 minutes or less is not necessarily high, even when mixed with type II anhydrous gypsum powder, it can be used without problems during molding, and is advantageous in terms of ensuring strength and toughness.

[0031] From the viewpoints of ensuring the above-mentioned MFR, ensuring high strength and toughness in the resin processed product after molding, and ease of availability, it is preferable that the thermoplastic resin contains polypropylene, and in particular, it is preferable that the polypropylene contains block polypropylene (block PP) or a block copolymer. In this case, the thermoplastic resin may contain 80% by mass or more and 100% by mass or more of polypropylene (block polypropylene) based on the total mass of the thermoplastic resin. Since polypropylene has a relatively small specific gravity, it is also advantageous from the viewpoint of ensuring flowability by securing its volume.

[0032] Block polypropylene (block PP) is polypropylene with EPR (ethylene propylene rubber) dispersed in it, and the dispersion of EPR can improve the mechanical strength.

[0033] (Other Ingredients) The resin processed raw material may be composed of only the above-mentioned II-type anhydrous gypsum powder and thermoplastic resin, but may additionally contain other components. For example, the resin processed raw material may contain at least one of a lipophilic surfactant and a coupling agent. In this case, the dispersion state of the II-type anhydrous gypsum powder and the thermoplastic resin becomes good, and the flowability during molding may be good. When at least one of a lipophilic surfactant and a coupling agent is contained, it is not desirable to have an excessive amount, and the content ratio of at least one of the lipophilic surfactant and the coupling agent may be 0.1 mass% or more and 5 mass% or less with respect to the total mass of the resin processed raw material.

[0034] The resin processed product raw material may contain at least one of a pigment and a dye. Since the inclusion of the pigment or dye affects the flowability during molding, the content ratio of the pigment or dye is preferably 0.1% by mass or more and 5% by mass or less with respect to the total mass of the resin processed product raw material.

[0035] <Manufacturing method> Next, an example of a method for producing the above-mentioned raw material for the resin processed product will be described.

[0036] 1 shows a schematic configuration of a production system S used for producing raw materials for resin processed products. The production system S includes a first crushing and separating device 1, a heating device 10, and a second crushing and separating device 20.

[0037] The first crushing and separating device 1 includes a hopper 2 that receives waste gypsum boards, a crushing section 3 that crushes the waste gypsum boards received by the hopper 2, and a separation section 4 that separates the crushed pieces crushed by the crushing section 3. The waste gypsum boards include a gypsum core material and paper attached to the gypsum core material. The crushed pieces crushed by the crushing section 3 include intermediate gypsum powder obtained by crushing the gypsum core material, and paper pieces obtained by crushing or breaking the paper. The separation section 4 separates the intermediate gypsum powder from the paper, for example, by vibrating a sieve.

[0038] The particle size of the intermediate gypsum powder pulverized in the first crushing and separating device 1 is not particularly limited, and the intermediate gypsum powder may be pulverized in a relatively coarse state (state in which the particle size varies widely). The particle size of the intermediate gypsum powder may be, for example, 15 mm or less, or about 5 mm or less. However, since the processing by the second crushing and separating device 20 in the subsequent stage can be performed smoothly and accurately if the intermediate gypsum powder is finely crushed in the first crushing and separating device 1, it is desirable that the particle size of the intermediate gypsum powder be about 5 mm or less.

[0039] A general gypsum board crushing device may be adopted as the first crushing / separating device 1. For example, a gypsum board processing system manufactured by Towa Kogyo Co., Ltd. or a gypsum board separator manufactured by Hosoda Kikaku Co., Ltd. may be adopted as the first crushing / separating device 1. However, the specific configuration of the first crushing / separating device 1 is not particularly limited.

[0040] The heating device 10 heats the intermediate gypsum powder pulverized in the first crushing and separating device 1. The heating device 10 heats the intermediate gypsum powder to convert it into type II anhydrous gypsum, and also performs heating to burn off residues including paper and / or plastic contained in the intermediate gypsum powder.

[0041] The intermediate gypsum powder pulverized in the first pulverizing and separating device 1 is so-called gypsum dihydrate (CaSO4·2H2O). In order to reliably convert the gypsum dihydrate into type II anhydrous gypsum and to reliably burn off the paper and plastic contained in the intermediate gypsum powder, heating at a high temperature is required. For this reason, it is preferable that the heating device 10 is capable of heating the intermediate gypsum powder to 700°C or higher, and preferably 800°C or higher. However, as long as the gypsum dihydrate can be reliably converted into type II anhydrous gypsum, the heating temperature is not particularly limited.

[0042] A kiln (rotary kiln) may be adopted as the heating device 10. However, the specific configuration of the heating device 10 is not particularly limited, and other furnaces or ovens may be adopted.

[0043] The second crushing and separating device 20 is a device that receives the intermediate gypsum powder heated by the heating device 10 and crushes it. In this example, the second crushing and separating device 20 is configured by an airflow type crusher having a classification function.

[0044] In detail, the second crushing and separating device 20 includes an inlet 21 for receiving intermediate gypsum powder, a fine crushing section 22 for crushing the intermediate gypsum powder received from the inlet 21 into fine gypsum powder, a classification section 23 for separating components having a larger particle size from the fine gypsum powder crushed in the fine crushing section 22, a collection section 24 for collecting the components having a larger particle size separated by the classification section 23, and an outlet 25 for taking out the fine gypsum powder. The fine gypsum powder formed here corresponds to type II anhydrous gypsum powder.

[0045] The fine pulverizing section 22 includes a rotor with blades, and the intermediate gypsum powder is pulverized into a fine state by dividing the intermediate gypsum powder with a swirling flow caused by the rotating rotor or by colliding the intermediate gypsum powder with itself. The classification section 23 separates the fine gypsum powder pulverized in the fine pulverizing section 22 from the residue containing sand contained in the intermediate gypsum powder. In this embodiment, the classification section 23 has a structure that allows the fine gypsum powder pulverized in the fine pulverizing section 22 to pass downstream and forms a clearance that restricts the passage of components with a particle size larger than that of the fine gypsum powder downstream. In this structure, the components whose passage is restricted by the classification section 23 are pulverized again by the fine pulverizing section 22 or drop out of the fine pulverizing section 22 and are accumulated below the rotor of the fine pulverizing section 22. In particular, components that cannot be pulverized into fine gypsum powder are sequentially accumulated below the rotor. However, the classifying section 23 may also have a structure in which, for example, air resistance and centrifugal force are applied to move the residue radially outward and discharge the fine gypsum powder in the rotor axial direction.

[0046] The type II anhydrous gypsum powder assumed for use in the present invention is one in which the particle diameter of 80% or more of the components in the particle diameter distribution is 10 μm or less, and is assumed to be obtained from intermediate gypsum powder. In order to enable such fine pulverization, the second pulverization and separation device 20 adjusts the rotation speed, classification clearance, raw material input amount (input amount of intermediate gypsum powder), air volume, etc. In the case of the above-mentioned particle diameter distribution, the particle diameter of many components in the fine gypsum powder is 10 μm or less. Here, the particle diameter of sand is generally about 20 μm to 2 mm, and when pulverization and classification are performed with the above-mentioned particle diameter distribution in mind, the residue containing sand can be accurately separated from the fine gypsum powder by the classification unit 23. This can suppress the state in which the residue is mixed into the fine gypsum powder.

[0047] When obtaining fine gypsum powder having the above-mentioned particle size distribution, in the classification section 23 of the second crushing and separating device 20 in this example, the classification clearance is set to between 1.5 mm and 3.0 mm, preferably between 1.5 mm and 2.5 mm, more preferably between 1.75 mm and 2.25 mm, specifically 2 mm in this example. Such a clearance is set to accurately separate the residue containing sand. In order to efficiently proceed with the refinement and the removal of the residue containing sand at the same time, it is desirable to set the classification clearance to between 1.5 mm and 3.0 mm, preferably between 1.5 mm and 2.5 mm, more preferably between 1.75 mm and 2.25 mm, specifically 2 mm in this example. However, the numerical value of the classification clearance is not particularly limited.

[0048] Furthermore, the fine gypsum powder pulverized by the fine pulverizing section 22 of the second pulverizing / separating device 20, which is an airflow pulverizer, loses its needle-like or plate-like crystal form and tends to become fine granules.

[0049] In this example, the residue separated by the classification unit 23 is not circulated as in a general airflow type pulverizer, but is collected by the collection unit 24. This can prevent the residue from being mixed into the fine gypsum powder finally taken out from the outlet 25. However, the residue collected by the collection unit 24 also contains gypsum components, which may be re-introduced into the inlet 21 in order to make effective use of them. In this case, it is preferable to remove sand from the residue and then re-introduce it into the inlet 21. In addition, when the fine gypsum powder is taken out from the outlet 25, applying vibration to the outlet 25 makes it easier to take out the fine gypsum powder. Although not shown, a vibration generator is provided at the outlet 25, and vibration is applied at a predetermined period.

[0050] As the second crushing and separating device 20, various airflow type crushers may be adopted, but a collecting section 24 is additionally provided. As the second crushing and separating device 20, for example, a SELENIMIRROR MKCL8-20 (registered trademark) manufactured by Masuko Sangyo Co., Ltd. may be used. Note that, although the second crushing and separating device 20 in this example is an airflow type crusher having a classification function, other crushing devices may be used and do not necessarily have a classification function as long as they can obtain type II anhydrous gypsum powder in which 80% or more of the components have a particle size of 10 μm or less in the particle size distribution assumed for use in the present invention.

[0051] Thereafter, the II-type anhydrous gypsum powder as the fine gypsum powder obtained from the second crushing and separating device 20 is mixed with a thermoplastic resin. Specifically, the II-type anhydrous gypsum powder and the thermoplastic resin are mixed so that the II-type anhydrous gypsum powder is contained in an amount of 55% by mass to 65% by mass and the thermoplastic resin is contained in an amount of 35% by mass to 45% by mass relative to the total mass of the resin processed raw material. At this time, the II-type anhydrous gypsum powder may be mixed with the molten thermoplastic resin, and then hardened to form pellets as the resin processed raw material.

[0052] When mixing the resin processed product, a pellet manufacturing device 30 including a mixer 31, an extruder 32, and a pelletizer 33 as shown in Fig. 1 may be used. In this case, after the II-type anhydrous gypsum powder and the thermoplastic resin are mixed in the mixer 31, the mixture is fed into the extruder 32, and the thermoplastic resin is melted and extruded into, for example, a string shape. Thereafter, the string-shaped mixture is cooled and then finely cut by the pelletizer 33 to form pellets as the raw material for the resin processed product.

[0053] When one or more of a surfactant, a coupling agent, a pigment and a dye are mixed into the raw material of the resin processed product, one or more of these may be added to a mixer in the second crushing and separating device 20 and / or the pellet manufacturing device and mixed therein.

[0054] 2 is a flow chart showing the procedure for producing raw materials for resin processed products by the production system S. The procedure for producing raw materials for resin processed products will be described in detail below.

[0055] First, in step S1, a first crushing and separation process (first crushing) is performed in which waste gypsum board containing a gypsum core material and paper attached to the gypsum core material is crushed to separate intermediate gypsum powder obtained by crushing the gypsum core material from paper pieces. In this example, in the first crushing and separation process, the intermediate gypsum powder is crushed so that 80% or more of the components of the intermediate gypsum powder are 5 mm or less in the particle size distribution of the intermediate gypsum powder. In this example, the first crushing and separation process is performed using a gypsum board separator manufactured by Hosoda Kikaku Co., Ltd. as the first crushing and separation device 1.

[0056] In step S2, the intermediate gypsum powder obtained in the first crushing and separation process is heated by the heating device 10 to convert it into type II anhydrous gypsum, and a heating process is performed to burn off residues including paper and / or plastic contained in the intermediate gypsum powder. In this example, the intermediate gypsum powder is heated at 800°C or higher for 3 hours or more. In this example, a kiln (rotary kiln) is used as the heating device 10 to perform the heating process.

[0057] In step S3, a second crushing and separation step (second crushing step) is performed in which the intermediate gypsum powder after the heating step is crushed and the residue is separated. In the second crushing and separation step, more specifically, the intermediate gypsum powder is crushed into fine gypsum powder by a second crushing and separation device 20, which is an airflow crusher, and the residue, including sand, contained in the intermediate gypsum powder is separated by a classification unit 23, and further collected and separated from the fine gypsum powder.

[0058] In this example, by using an airflow pulverizer, foreign matter (residue) is removed at the same time as the intermediate gypsum powder is pulverized in the second pulverization / separation process, so that the desired high-purity fine gypsum powder can be extracted efficiently and easily, and the tact time can be significantly reduced compared to when a sieve is used, for example. Note that, although pulverization and separation are performed simultaneously in the second pulverization / separation process, separation does not necessarily have to be performed.

[0059] Fig. 3 shows an SEM image of an example of type II anhydrous gypsum powder, which is fine gypsum powder produced by the manufacturing system S (produced by step S3 above). Fig. 3 shows that the fine gypsum powder is a non-acicular crystal and a non-plate-like crystal, and is in the form of fine granules. In addition, as can be seen by comparing with the scale in Fig. 3, the particle diameters of many components of the fine gypsum powder are 10 µm or less.

[0060] Table 1 below shows the measurement results of the particle size distribution of type II anhydrous gypsum powder generated by the manufacturing system S. Table 1 below shows the measurement results when grinding was performed using two different operation patterns, first and second. The difference between the first and second operation patterns is the amount of intermediate gypsum powder added, which is 2.00 kg for the former and 3.46 kg for the latter. Due to the difference in the amount added, the amount added per unit time differs between the first and second operation patterns.

[0061] [Table 1]

[0062] Fig. 4 shows a graph representing the particle size distribution shown in Table 1. The line indicated by the symbol A in Fig. 4 represents the particle size distribution of the fine gypsum powder pulverized by the first operation pattern, and the line indicated by the symbol B represents the particle size distribution of the fine gypsum powder pulverized by the second operation pattern. According to the manufacturing system S, type II anhydrous gypsum powder having a particle size of 10 μm or less can be stably obtained.

[0063] In addition, the following Table 2 shows the measurement results of the component analysis of the type II anhydrous gypsum powder generated by the manufacturing system S by wavelength dispersive X-ray fluorescence analysis.

[0064] [Table 2]

[0065] The results in Table 2 show that the combined value of the Ca component and the S component was 90.8 mass %, indicating that the gypsum component was contained at a high purity.

[0066] 2, the high-purity and fine II-type anhydrous gypsum powder produced in step S3 is mixed with a thermoplastic resin in step S10. The process in step S10 corresponds to, for example, the mixing in the mixer 31 described above. Thereafter, in step S11, a resin processed material containing the II-type anhydrous gypsum powder and a thermoplastic resin is produced. The process in step S11 corresponds to, for example, the processes in the extruder 32 and pelletizer 33 described above.

[0067] The resin processed raw material is then used as a molding raw material for a resin processed product in step S12. For example, the resin processed raw material can be melted, poured into a mold, and cured to form a resin processed product.

[0068] The resin processed product raw material according to the present embodiment described above can ensure suitable fluidity during molding of the resin processed product. This can improve the processing accuracy of the resin processed product. In addition, since more than half of the components in the resin processed product raw material by mass are hard type II anhydrous gypsum powder, the strength of the resin processed product can be ensured, while the sufficient content of thermoplastic resin can ensure the toughness of the resin processed product. Furthermore, since the particle diameter of many components in type II anhydrous gypsum powder is 10 μm or less, the roughness of the surface of the finished resin processed product is suppressed, and there are also advantages such as easing restrictions on the use of the resin processed product. [Explanation of symbols]

[0069] Reference Signs List 1: first crushing and separating device, 2: hopper, 3: crushing section, 4: separating section, 10: heating device, 20: second crushing and separating device, 21: inlet, 22: fine crushing section, 23: classifying section, 24: collecting section, 30: pellet manufacturing device, 31: mixer, 32: extruder, 33: pelletizer

Claims

1. A resin processed raw material containing type II anhydrous gypsum powder and a thermoplastic resin, The type II anhydrous gypsum powder is contained in an amount of 55% by mass or more and 65% by mass or less based on the total mass of the resin processed raw material, The thermoplastic resin is contained in an amount of 35% by mass or more and 45% by mass or less based on the total mass of the resin processed raw material, The type II anhydrous gypsum powder is a raw material for resin processed products, in which 80% or more of the components in the particle size distribution have a particle size of 10 μm or less.

2. The melt flow rate of the thermoplastic resin is 4 g / 10 min or more and 6 g / 10 min or less when measured in accordance with JIS K 7210-1:2014 at a temperature of 230 ° C. and a load of 2.16 kg. The raw material for resin processed products according to claim 1.

3. The resin processed material according to claim 1 or 2, wherein the thermoplastic resin includes polypropylene.

4. The resin processed material according to claim 3 , wherein the thermoplastic resin contains block polypropylene as the polypropylene.

5. The resin processed product raw material according to claim 4 , wherein the thermoplastic resin contains 80% by mass or more and 100% by mass or more of block polypropylene based on the total mass of the thermoplastic resin.

6. The resin processed material according to claim 1 or 2, wherein the type II anhydrous gypsum powder is a non-needle crystal and a non-plate crystal, and the type II anhydrous gypsum component is 90 mass% or more relative to the total.

7. The resin processed material according to claim 1, wherein the type II anhydrous gypsum powder is obtained from waste gypsum board.

8. 2. The resin processed material according to claim 1, further comprising at least one of a lipophilic surfactant and a coupling agent in an amount of 0.1% by mass to 5% by mass based on the total mass of the resin processed material.

9. The resin processed material according to claim 1 or 8, further comprising at least one of a pigment and a dye in an amount of 0.1% by mass to 5% by mass based on the total mass of the resin processed material.

10. A first crushing step of crushing a waste gypsum board including a gypsum core material and paper attached to the gypsum core material, and separating an intermediate gypsum powder obtained by crushing the gypsum core material from the paper; A heating step of heating the intermediate gypsum powder to convert it into type II anhydrous gypsum and burning off residues including paper and / or plastic contained in the intermediate gypsum powder; A second crushing step of crushing the intermediate gypsum powder after the heating step into fine gypsum powder; A raw material preparation process for preparing a resin processed raw material by mixing the fine gypsum powder as type II anhydrous gypsum powder with a thermoplastic resin, The type II anhydrous gypsum powder has a particle size distribution in which 80% or more of the components have a particle size of 10 μm or less, In the raw material preparation process, the type II anhydrous gypsum powder and the thermoplastic resin are mixed so that the type II anhydrous gypsum powder is contained in an amount of 55 mass% or more and 65 mass% or less relative to the total mass of the resin processed raw material, and the thermoplastic resin is contained in an amount of 35 mass% or more and 45 mass% or less relative to the total mass of the resin processed raw material. This is a manufacturing method for a resin processed raw material using waste gypsum board.

11. The method for producing a resin processed raw material using waste gypsum board according to claim 10, wherein in the raw material preparation process, the molten thermoplastic resin is mixed with the type II anhydrous gypsum powder, and then hardened to form pellets as the resin processed raw material.

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