Raw material for processed resin objects and method for producing same

Abstract

This raw material for processed resin objects comprises a powder of type II anhydrous gypsum and a thermoplastic resin. The powder of type II anhydrous gypsum is contained in an amount of 55-65 mass% with respect to the total mass of the raw material for processed resin objects, the thermoplastic resin is contained in an amount of 35-45 mass% with respect to the total mass of the raw material for processed resin objects, and the powder of type II anhydrous gypsum has a particle diameter distribution in which 80% or more is accounted for by components having particle diameters of 10 μm or less.

Description

Raw Material for Resin Processed Product and Method for Producing the Same

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

[0002] Gypsum board is extremely useful as a building material and is widely used in various structures. On the other hand, the amount of waste gypsum board generated when, for example, demolishing structures is enormous and tends to increase further in the future.

[0003] Waste gypsum board is recyclable; specifically, gypsum and paper extracted from waste gypsum board can be recycled as recycled resources. At present, when recycling is performed, most of the gypsum extracted from, for example, waste gypsum board is used for remanufacturing gypsum board or as a solidifying material for sludge or the like. However, the amount of recycled waste gypsum board is very small compared to the total generated amount of waste gypsum board. In fact, most waste gypsum board is landfilled. That is, it cannot necessarily be said that the improvement and spread of the recycling environment for waste gypsum board are progressing as desired.

[0004] Landfill disposal of waste gypsum board is currently carried out at managed industrial waste disposal sites. However, industrial waste disposal sites have limitations in securing sites, and it is desirable to avoid their operation as much as possible in order to suppress environmental load and health damage.

[0005] In view of the above circumstances, realization of an environment where as much waste gypsum board as possible can be recycled is desired. Under these circumstances, various technologies related to the treatment of waste gypsum board have been proposed in the past, and are disclosed in, for example, Patent Documents 1 to 4.

[0006] Patent Document 1: Japanese Unexamined Patent Publication No. 2023-36207 Patent Document 2: Japanese Unexamined Patent Publication No. 2023-36205 Patent Document 3: Japanese Unexamined Patent Publication No. 2022-24689 Patent Document 4: Japanese Patent No. 6088277

[0007] The inventors of this case believe that the following reasons (1) to (4) are the undesirable reasons why the improvement and widespread adoption of the recycling environment for waste gypsum board is not progressing: (1) The main uses of gypsum extracted from waste gypsum board (remanufacturing of gypsum board and solidification material) are currently very limited. In other words, the market is limited, and many companies are not interested in entering it. (2) The gypsum extracted from waste gypsum board is generally required to be so-called dihydrate gypsum and in an acicular crystalline state. In other words, such characteristics or properties restrict the uses of reuse and make it difficult to expand the market (uses). (3) The gypsum extracted from waste gypsum board currently contains a certain amount of foreign matter such as sand and plastic. Such foreign matter can cause undesirable environmental effects, for example, and restricts its uses. (4) Recycling waste gypsum board is costly and time-consuming. This is a barrier to entry.

[0008] Based on the above circumstances, the inventors of this case conducted thorough research and found that the applications of gypsum extracted from waste gypsum board can be expanded by improving its properties and manufacturing process.

[0009] Specifically, the inventors of this invention have found that by extracting gypsum from waste gypsum board as fine anhydrous gypsum, particularly type II anhydrous gypsum, and properly removing impurities, the uses of gypsum extracted from waste gypsum board can be significantly expanded.

[0010] More specifically, high-purity, fine-grained Type II anhydrous gypsum can be used, for example, as a raw material for resin products that are environmentally conscious and have excellent processing precision. Because such gypsum-containing resin raw materials contain few or no impurities, they are expected to be used in the consumer sector.

[0011] The inventors of this invention believed that in order to expand the applications of resin processing materials by making them usable in various molding processes (mold processing), it would be beneficial to produce resin processing materials by mixing anhydrous type II gypsum with thermoplastic resin. Resin processing products formed from such resin processing materials have the advantage of potentially having improved strength due to the use of anhydrous type II gypsum compared to products made solely from thermoplastic resin. Above all, the use of recycled materials is of great significance in the current climate of increasingly serious environmental problems.

[0012] However, since Type II anhydrous gypsum does not change its form even when heated to the temperature at which thermoplastic resins melt, it impairs the fluidity of the thermoplastic resin during molding, and depending on the content of Type II anhydrous gypsum, proper processing may not be possible. In addition, Type II anhydrous gypsum can cause surface roughness of processed products, which may limit their applications. Furthermore, depending on the content of Type II anhydrous gypsum, while strength may be good, toughness may be poor, which may also limit its applications.

[0013] On the other hand, reducing the content of anhydrous type II gypsum can resolve the fluidity problem during molding. However, this would reduce the strength of the finished product, diminish the significance of using recycled materials, and lose its appeal to environmental concerns.

[0014] From the above perspective, the inventors of this case have diligently researched a resin processing material containing type II anhydrous gypsum and a thermoplastic resin that can obtain the advantage of improved strength of molded products made with type II anhydrous gypsum, suppress the decrease in toughness, and ensure suitable fluidity during molding.

[0015] This invention was conceived against the above background, and aims to provide a resin material and a method for manufacturing the same that can form a resin workpiece with good processing accuracy, good strength and toughness, by ensuring suitable fluidity during molding of the resin workpiece.

[0016] The present invention relates to the following [1] to [5].

[0017] [1] A resin processed material comprising anhydrous gypsum powder of type II and a thermoplastic resin, wherein the anhydrous gypsum powder of type II is contained in an amount of 55% by mass or more and 65% by mass or less of the total mass of the resin processed material, the thermoplastic resin is contained in an amount of 35% by mass or more and 45% by mass or less of the total mass of the resin processed material, and the particle size distribution of the anhydrous gypsum powder of type II is such that 80% or more of the components have a particle size of 10 μm or less.

[0018] [2] A resin processed material comprising type II anhydrous gypsum powder and a thermoplastic resin, wherein the type II anhydrous gypsum powder is contained in an amount of 55% by mass or more and 65% by mass or less of the total mass of the resin processed material, the thermoplastic resin is contained in an amount of 35% by mass or more and 45% by mass or less of the total mass of the resin processed material, 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, the type II anhydrous gypsum powder is a non-acicular and non-plate-like crystalline material, and the type II anhydrous gypsum component accounts for 90% by mass or more of the whole, and the type II anhydrous gypsum powder is obtained from waste gypsum board.

[0019] [3] A waste gypsum board containing a gypsum core and paper attached to the gypsum core is crushed, and a first crushing step is made to separate the crushed gypsum core from the paper; a heating step is made to heat the intermediate gypsum powder to make type II anhydrous gypsum and to burn off any residue containing paper and / or plastic in the intermediate gypsum powder; a second crushing step is made to crush the intermediate gypsum powder after the heating step into fine gypsum powder; and a raw material production step is made to produce a resin processed raw material by mixing the fine gypsum powder as type II anhydrous gypsum powder with a thermoplastic resin, wherein 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. A method for producing a resin processed material using waste gypsum board, wherein in the raw material preparation step, the anhydrous gypsum powder of type II is mixed with the thermoplastic resin such that the anhydrous gypsum powder is contained in an amount of 55% by mass or more and 65% by mass or less relative to the total mass of the resin processed material, and the thermoplastic resin is contained in an amount of 35% by mass or more and 45% by mass or less relative to the total mass of the resin processed material.

[0020] [4] A waste gypsum board containing a gypsum core and paper attached to the gypsum core is crushed, and a first crushing step is taken to separate the crushed gypsum core from the paper; a heating step is taken to heat the intermediate gypsum powder to 700°C or higher to make type II anhydrous gypsum, and to burn off any residue containing paper and / or plastic in the intermediate gypsum powder; a second crushing step is taken to crush the intermediate gypsum powder after the heating step into fine gypsum powder; and a raw material production step is taken to produce a resin processed raw material by mixing the fine gypsum powder as type II anhydrous gypsum powder with a thermoplastic resin, wherein 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. A method for producing a resin processed material using waste gypsum board, wherein in the raw material preparation step, the anhydrous gypsum powder of type II is mixed with the thermoplastic resin such that the anhydrous gypsum powder is contained in an amount of 55% by mass or more and 65% by mass or less relative to the total mass of the resin processed material, and the thermoplastic resin is contained in an amount of 35% by mass or more and 45% by mass or less relative to the total mass of the resin processed material.

[0021] [5] Anhydrous gypsum powder of type II used in the manufacture of a resin processed product raw material by mixing with a thermoplastic resin, wherein the thermoplastic resin is contained in an amount of 35% by mass or more and 45% by mass or less with respect to the total mass of the resin processed product raw material, and is contained in an amount of 55% by mass or more and 65% by mass or less with respect to the total mass of the resin processed product raw material, and the particle size distribution of 80% or more of the components is 10 μm or less.

[0022] According to the present invention, it is possible to form resin workpieces that have good processing accuracy, good strength and toughness, and can be made by ensuring suitable fluidity during molding.

[0023] This figure shows a schematic configuration of an example of a system used for manufacturing resin processed material according to the present invention. This is a flowchart showing the manufacturing procedure for resin processed material using the system shown in Figure 1. This figure shows an SEM image of an example of type II anhydrous gypsum powder used in resin processed material according to the present invention. This figure shows a graph of an example of particle size distribution of type II anhydrous gypsum powder used in resin processed material according to the present invention.

[0024] An embodiment of the present invention will be described below.

[0025] <Raw Materials for Resin-Processed Products> A raw material for resin-processed products according to one embodiment of the present invention is a raw material for resin-processed products comprising type II anhydrous gypsum powder and a thermoplastic resin. Specifically, the raw material for resin-processed products according to this embodiment contains type II anhydrous gypsum powder in an amount of 55% to 65% by mass of its total mass, and thermoplastic resin in an amount of 35% to 45% by mass of its total mass. Furthermore, in the particle size distribution, 80% or more of the components of the type II anhydrous gypsum powder contained in the raw material for resin-processed products have a particle size of 10 μm or less.

[0026] The specific gravity of type II anhydrous gypsum powder is generally 2.97 g / cm³, and the specific gravity of thermoplastic resin is generally 0.9 to 1.0 g / cm³. In this case, by setting the content of type II anhydrous gypsum powder to 55% to 65% by mass and the content of thermoplastic resin to 35% to 45% by mass, the ratio of the volume of type II anhydrous gypsum powder to the volume of thermoplastic resin becomes approximately 1:2. In this case, when the thermoplastic resin is melted and mixed with type II anhydrous gypsum powder, it can coat each particle of type II anhydrous gypsum powder with a thickness of about half the particle diameter. Furthermore, since the particle size distribution of type II anhydrous gypsum powder shows that 80% or more of the components have a particle size of 10 μm or less, the type II anhydrous gypsum powder disperses easily in the thermoplastic resin, and a coating state of type II anhydrous gypsum powder by the thermoplastic resin is easily formed. As a result, when anhydrous gypsum powder of type II is mixed with a thermoplastic resin, a sea-island structure can be suitably formed in which the thermoplastic resin forms the sea phase and the anhydrous gypsum powder of type II forms the island phase.

[0027] As a result, the resin material according to this embodiment ensures suitable fluidity during the molding of the resin product. This can lead to improved processing accuracy of the resin product. Furthermore, since more than half of the mass ratio of the resin material consists of hard type II anhydrous gypsum powder, good strength of the resin product can be ensured, while the sufficient inclusion of thermoplastic resin ensures good toughness of the resin product. Moreover, since the particle size of many components in the type II anhydrous gypsum powder is 10 μm or less, surface roughness of the finished resin product is suppressed, and there are other advantages such as the relaxation of restrictions on the application of the resin product. The components of the resin material and components that can be selectively added will be described in detail below.

[0028] (Type II Anhydrous Gypsum Powder) As mentioned above, Type II anhydrous gypsum powder contained in resin processed raw materials has a particle size distribution in which 80% or more of the components have a particle size of 10 μm or less. The particle size distribution of Type II anhydrous gypsum powder is measured using a laser diffraction / scattering particle size distribution analyzer (Microtrac MT3300EXII manufactured by Microtrac Bell Co., Ltd.). Specifically, isopropyl alcohol (refractive index 1.38) is selected as the solvent, a refractive index of 1.81 is selected for the particle conditions, permeability is selected as permeable, and non-spherical is selected for the particle shape.

[0029] Furthermore, the Type II anhydrous gypsum powder used in this embodiment is a non-acicular and non-plate-shaped crystalline material. Gypsum is generally an acuicular crystalline material, and this characteristic is utilized to improve bonding strength with other materials, among other advantages. However, the Type II anhydrous gypsum powder used in this embodiment is deliberately made into a non-acicular and non-plate-shaped crystalline material, thereby suppressing adverse effects on fluidity during molding. The state of being a non-acicular and non-plate-shaped crystalline material is obtained by finely grinding the Type II anhydrous gypsum powder.

[0030] Furthermore, Type II anhydrous gypsum powder is defined as having a Type II anhydrous gypsum component of 90% by mass or more of the total. The state of having a Type II anhydrous gypsum component of 90% by mass or more in 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% by mass or more. The mass ratio of Type II anhydrous gypsum components in Type II anhydrous gypsum powder is determined by calculating the Ca component and the S component using wavelength-dispersive X-ray fluorescence analysis and then summing them up.

[0031] In this embodiment, it is assumed that the Type II anhydrous gypsum powder described above is obtained from waste gypsum board. This ensures that the raw materials for the resin processed product consist mostly of recycled materials, thus providing an appeal to environmental concerns. However, the Type II anhydrous gypsum powder does not necessarily have to be obtained from waste gypsum board.

[0032] (Thermoplastic Resins) The thermoplastic resins that make up the raw materials for resin processed products include, for example, one or more of the following: polypropylene, polyethylene, polystyrene, polyvinyl chloride, polyacetal, polyamide, polyethylene terephthalate, polycarbonate, polyphenylene sulfide, polyamide-imide, and polyetheretherketone. However, thermoplastic resins other than those exemplified herein may also be used.

[0033] Preferably, the thermoplastic resin used has a melt flow rate (MFR) of 4 g / 10 min or more and 6 g / 10 min or less, measured under conditions of JIS K 7210-1:2014, at a temperature of 230°C and a load of 2.16 kg. Such an MFR ensures suitable fluidity during molding and high strength and toughness in the molded resin product. While a higher MFR of a thermoplastic resin allows for higher material fluidity during molding, it generally tends to decrease the strength and toughness of the molded resin product due to the lower molecular weight. An MFR of 4 g / 10 min or more and 6 g / 10 min or less is not necessarily high, but it can be used without problems during molding even when mixed with type II anhydrous gypsum powder, and is advantageous in terms of ensuring strength and toughness.

[0034] From the viewpoint of ensuring the above-mentioned MFR, ensuring high strength and toughness in the resin processed product after molding, and ease of availability, the thermoplastic resin preferably contains polypropylene, and in particular, it is preferable that the polypropylene contains block polypropylene (block PP) or block copolymer. In this case, the thermoplastic resin may contain 80% to 100% by mass of polypropylene (block polypropylene) based on the total mass of the thermoplastic resin. Polypropylene has a relatively low specific gravity, which is advantageous from the viewpoint of ensuring fluidity by securing its volume.

[0035] Block polypropylene (block PP) is a material in which EPR (ethylene propylene rubber) is dispersed in polypropylene, and the dispersion of EPR can improve its mechanical strength.

[0036] (Other components) The resin material may consist only of the type II anhydrous gypsum powder and thermoplastic resin as described above, but may also contain other components. For example, the resin material may contain at least one of a lipophilic surfactant and a coupling agent. In this case, the dispersion state of the type II anhydrous gypsum powder and the thermoplastic resin will be good, and the fluidity during molding may be good. When at least one of the lipophilic surfactant and the coupling agent is included, it is not desirable to include an excessive amount, and the content ratio of at least one of the lipophilic surfactant and the coupling agent may be 0.1% by mass or more and 5% by mass or less of the total mass of the resin material.

[0037] Furthermore, the resin processed material may contain at least one of pigments and dyes. Since the content of pigments and dyes affects the fluidity during molding, it is desirable that their content be between 0.1% and 5% by mass relative to the total mass of the resin processed material.

[0038] <Manufacturing Method> Next, an example of a manufacturing method for the resin processed material raw material described above will be explained.

[0039] Figure 1 shows a schematic configuration of a manufacturing system S used for producing raw materials for resin processed products. The manufacturing system S comprises a first crushing and separation device 1, a heating device 10, and a second crushing and separation device 20.

[0040] The first crushing and separating apparatus 1 includes a hopper 2 for receiving waste gypsum board, a crushing unit 3 for crushing the waste gypsum board received in the hopper 2, and a separating unit 4 for separating the crushed fragments from the crushing unit 3. The waste gypsum board includes a gypsum core material and paper attached to the gypsum core material. The crushed fragments crushed in the crushing unit 3 include intermediate gypsum powder obtained by crushing the gypsum core material and paper fragments obtained by crushing or tearing the paper. The separating unit 4 separates the intermediate gypsum powder from the paper, for example, by vibrating a sieve.

[0041] The particle size of the intermediate gypsum powder pulverized in the first pulverizing and separating apparatus 1 is not particularly limited, and may be pulverized in a relatively coarse state (a state in which the particle size varies greatly). The particle size of the intermediate gypsum powder may be, for example, 15 mm or less, or about 5 mm or less. However, finely pulverizing the intermediate gypsum powder in the first pulverizing and separating apparatus 1 allows the treatment performed in the subsequent second pulverizing and separating apparatus 20 to be performed smoothly and with high accuracy, so it is desirable that the particle size of the intermediate gypsum powder is about 5 mm or less.

[0042] As the first pulverizing and separating apparatus 1, a conventional gypsum board pulverizing apparatus may be employed. As the first pulverizing and separating apparatus 1, for example, a gypsum board processing system manufactured by Towa Kogyo Co., Ltd., or a gypsum board separator manufactured by Hosoda Planning Co., Ltd. may be employed. However, the specific configuration of the first pulverizing and separating apparatus 1 is not particularly limited.

[0043] The heating device 10 heats the intermediate gypsum powder pulverized by the first pulverizing and separating apparatus 1. The heating device 10 performs heating to convert the intermediate gypsum powder into type II anhydrous gypsum, and to burn off residues containing paper and / or plastic contained in the intermediate gypsum powder.

[0044] The intermediate gypsum powder pulverized by the first pulverizing and separating apparatus 1 is so-called dihydrate gypsum (CaSO₄·2H₂O). Heating at a high temperature is required to reliably convert dihydrate gypsum into type II anhydrous gypsum and reliably burn off paper and plastic contained in the intermediate gypsum powder. Therefore, it is preferable that the heating device 10 is capable of heating the intermediate gypsum powder at 700°C or higher, preferably 800°C or higher. The heating temperature for converting the intermediate gypsum powder into type II anhydrous gypsum may be 700°C or higher, 720°C or higher, 740°C or higher, 760°C or higher, 780°C or higher, or 800°C or higher. The heating temperature for converting the intermediate gypsum powder into type II anhydrous gypsum may be 1000°C or lower, 980°C or lower, 960°C or lower, 940°C or lower, 920°C or lower, or 900°C or lower. However, the temperature during heating is not particularly limited as long as dihydrate gypsum can be reliably converted into type II anhydrous gypsum.

[0045] As the heating device 10, a kiln (rotary kiln) may be employed. However, the specific configuration of the heating device 10 is not particularly limited, and other furnaces or kilns may be employed.

[0046] The second pulverizing and separating device 20 is a device that receives and pulverizes intermediate gypsum powder heated by the heating device 10. In this example, the second pulverizing and separating device 20 is constituted by an airflow pulverizer having a classification function.

[0047] Specifically, the second pulverizing and separating device 20 includes an input port 21 that receives intermediate gypsum powder, a fine pulverizing section 22 that pulverizes the intermediate gypsum powder received from the input port 21 into fine gypsum powder, a classifying section 23 that separates components having a larger particle diameter from the fine gypsum powder pulverized by the fine pulverizing section 22, a collecting section 24 that collects the large particle diameter components separated by the classifying section 23, and an outlet 25 for taking out the fine gypsum powder. The fine gypsum powder formed herein corresponds to type II anhydrous gypsum powder.

[0048] The fine pulverizing section 22 includes a bladed rotor, and pulverizes the intermediate gypsum powder into a fine state by dividing the intermediate gypsum powder or causing collision between intermediate gypsum powder particles through a swirling flow generated by the rotating rotor. The classifying section 23 separates the fine gypsum powder pulverized by the fine pulverizing section 22 from residues including sand contained in the intermediate gypsum powder. In the present embodiment, the classifying section 23 has a structure that forms a clearance which allows passage of the fine gypsum powder pulverized by the fine pulverizing section 22 to the downstream side, and restricts passage of components having a larger particle diameter than the fine gypsum powder to the downstream side. In this structure, components whose passage is restricted by the classifying section 23 are either pulverized again by the fine pulverizing section 22 or fall off from the fine pulverizing section 22, and accumulate below the rotor of the fine pulverizing section 22. In particular, components that cannot be pulverized into fine gypsum powder sequentially accumulate below the rotor. However, the classifying section 23 may also have a structure in which, for example, aerodynamic drag and centrifugal force are applied to move residues radially outward and discharge fine gypsum powder in the rotor axial direction.

[0049] The Type II anhydrous gypsum powder intended for use in this invention has a particle size distribution in which 80% or more of the components have a particle size of 10 μm or less, and is intended to be obtained from intermediate gypsum powder. In the Type II anhydrous gypsum powder contained in the raw material for resin processed products, the particle size of 80% or more of the components in the particle size distribution may be 8 μm or less, or 5 μm or less. In the second grinding and separation device 20, the rotation speed, classification clearance, raw material input amount (amount of intermediate gypsum powder input), airflow rate, etc. are adjusted so that such fine grinding is possible. With the above particle size distribution, the particle size of many components in the fine gypsum powder will be 10 μm or less, and furthermore, it can be 8 μm or less or 5 μm or less. Here, the particle size of sand is generally about 20 μm to 2 mm, and when grinding and classification are performed with the above particle size 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 mixing of residue into the fine gypsum powder.

[0050] When obtaining fine gypsum powder with the particle size distribution described above, the classification clearance in the classification section 23 of the second grinding and separation apparatus 20 in this example 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 advance both fine grinding and the removal of the residue containing sand simultaneously, 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.

[0051] Furthermore, the fine gypsum powder pulverized by the fine pulverization section 22 of the second pulverization and separation device 20, which is an air-flow type pulverizer, tends to lose its needle-shaped or plate-shaped crystalline form and become fine granular material.

[0052] The residue separated in the classification section 23 is collected by the collection section 24 in this example, without being circulated as in a typical air-jet pulverizer. This helps to suppress the inclusion of residue in the fine gypsum powder that is ultimately removed from the outlet 25. However, the residue collected in the collection section 24 also contains gypsum components, which may be reintroduced to the input port 21 for effective use. In this case, it is desirable to remove the sand from the residue before reintroducing it to the input port 21. Furthermore, when removing the fine gypsum powder from the outlet 25, applying vibration to the outlet 25 makes it easier to remove the fine gypsum powder. Although not shown in the diagram, a vibration generator is provided at the outlet 25, and vibration is applied at a predetermined frequency.

[0053] Various types of air-flow pulverizers can be used as the second pulverization and separation device 20, but a collection unit 24 is additionally provided. For example, the selenium mirror MKCL8-20 (registered trademark) manufactured by Masuko Sangyo Co., Ltd. may be used as the second pulverization and separation device 20. In this example, the second pulverization and separation device 20 is an air-flow pulverizer with a classification function, but other pulverizers may be used as long as they can produce type II anhydrous gypsum powder in which the particle size of 80% or more of the components in the particle size distribution intended for use in the present invention have a particle size of 10 μm or less, and the device does not necessarily have to have a classification function.

[0054] Subsequently, the type II anhydrous gypsum powder obtained from the second pulverization and separation device 20 is mixed with the thermoplastic resin. Specifically, the type II anhydrous gypsum powder and the thermoplastic resin are mixed such that the type II anhydrous gypsum powder is contained in an amount of 55% to 65% by mass relative to the total mass of the resin processed material, and the thermoplastic resin is contained in an amount of 35% to 45% by mass relative to the total mass of the resin processed material. At this time, pellets for the resin processed material may be formed by mixing the type II anhydrous gypsum powder with the molten thermoplastic resin and then curing it.

[0055] When mixing resin products, a pellet manufacturing apparatus 30 including a mixer 31, an extruder 32, and a pelletizer 33, as shown in Figure 1, may be used. In this case, after the type II anhydrous gypsum powder and thermoplastic resin are mixed in the mixer 31, the mixture is fed into the extruder 32, where the thermoplastic resin is melted and extruded, for example, into a string shape. After the string-shaped mixture is cooled, it is finely cut by the pelletizer 33 to form pellets that will be used as raw materials for resin products.

[0056] When adding one or more of surfactants, coupling agents, pigments, and dyes to the resin processed material, one or more of these may be introduced into the mixer in the second crushing and separation device 20 and / or the pellet manufacturing device and mixed.

[0057] Figure 2 is a flowchart showing the manufacturing procedure for resin processed raw materials using manufacturing system S. The manufacturing procedure for resin processed raw materials will be explained in detail below.

[0058] First, in step S1, a first crushing and separation step (first crushing) is performed to crush the waste gypsum board containing the gypsum core material and the paper attached to the gypsum core material, and separate the crushed intermediate gypsum powder from the paper fragments. In this example, in the first crushing and separation step, the intermediate gypsum is crushed so that 80% or more of the components of the intermediate gypsum powder have a particle size distribution of 5 mm or less. In this example, the first crushing and separation step is performed using a gypsum board separator manufactured by Hosoda Kikaku Co., Ltd. as the first crushing and separation device 1.

[0059] In step S2, the intermediate gypsum powder obtained in the first pulverization and separation step is heated by the heating device 10 to convert it into type II anhydrous gypsum, and a heating process is performed to burn off any residues containing paper and / or plastic in the intermediate gypsum powder. In this example, the intermediate gypsum powder is heated at 800°C to 900°C for 3 hours or more. In this example, a kiln (rotary kiln) is used as the heating device 10 to perform the heating process.

[0060] In step S3, a second grinding and separation step (second grinding step) is performed to grind the intermediate gypsum powder after the heating step and separate the residue. Specifically in the second grinding and separation step, the intermediate gypsum powder is ground into fine gypsum powder using a second grinding and separation device 20, which is an air-flow type grinder, and the residue containing sand contained in the intermediate gypsum powder is separated in the classification unit 23, and further collected and separated from the fine gypsum powder.

[0061] In this example, by using an air-jet pulverizer, foreign matter (residue) is removed simultaneously with the pulverization of the intermediate gypsum powder in the second pulverization and separation process. This allows for the efficient and simple extraction of the desired high-purity fine gypsum powder, significantly reducing the cycle time compared to, for example, using a sieve. Although pulverization and separation are performed simultaneously in the second pulverization and separation process, separation is not required.

[0062] Figure 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 in step S3 above). In Figure 3, it can be seen that the fine gypsum powder consists of non-acicular and non-plate-like crystals and is in the form of fine granules. Furthermore, the particle size of many components of the fine gypsum powder is 10 μm or less, which is clear when compared with the scale in Figure 3.

[0063] Table 1 below shows the measurement results of the particle size distribution of Type II anhydrous gypsum powder produced by manufacturing system S. Table 1 below shows the measurement results when grinding was performed using two different operating patterns, the first and second. The difference between the first and second operating patterns is the amount of intermediate gypsum powder input; the former was 2.00 kg, and the latter was 3.46 kg. Due to the difference in input amount, there is a difference in the input amount per unit time between the first and second operating patterns.

[0064]

[0065] Figure 4 shows a graph representing the particle size distribution shown in Table 1. In Figure 4, the line labeled A shows the particle size distribution of fine gypsum powder ground in the first operating pattern, and the line labeled B shows the particle size distribution of fine gypsum powder ground in the second operating pattern. According to the manufacturing system S, anhydrous type II gypsum powder with a particle size of 10 μm or less can be stably obtained.

[0066] Furthermore, Table 2 below shows the measurement results of the component analysis of Type II anhydrous gypsum powder produced by manufacturing system S, obtained by wavelength-dispersive X-ray fluorescence analysis.

[0067]

[0068] The results in Table 2 show that the combined value of Ca and S components is 90.8% by mass, indicating that the gypsum component is present in high purity.

[0069] Returning to Figure 2, the high-purity, fine type II anhydrous gypsum powder produced in step S3 is mixed with the thermoplastic resin in step S10. The process in step S10 corresponds, for example, to mixing in the mixer 31 described above. Subsequently, in step S11, a resin product raw material containing the type II anhydrous gypsum powder and the thermoplastic resin is produced. The process in step S11 corresponds, for example, to the process in the extruder 32 and pelletizer 33 described above.

[0070] Then, in step S12, the resin processing material is used as a molding material for the resin processed product. For example, after melting, the resin processing material can be poured into a mold and hardened to form a resin processed product.

[0071] The resin material according to this embodiment described above ensures suitable fluidity during the molding of the resin product. This can lead to improved processing accuracy of the resin product. Furthermore, since more than half of the mass ratio of the resin material consists of hard type II anhydrous gypsum powder, good strength of the resin product can be ensured, while the sufficient inclusion of thermoplastic resin ensures good toughness of the resin product. Moreover, since the particle size of many components in the type II anhydrous gypsum powder is 10 μm or less, surface roughness of the finished resin product is suppressed, which also has advantages such as easing restrictions on the application of the resin product.

[0072] 1...First grinding and separation device, 2...Hopper, 3...Grinding section, 4...Separation section, 10...Heating device, 20...Second grinding and separation device, 21...Inlet, 22...Fine grinding section, 23...Classification section, 24...Collection section, 30...Pellet manufacturing device, 31...Mixer, 32...Extruder, 33...Pelletizer

Claims

1. A resin processing material comprising anhydrous gypsum powder of type II and a thermoplastic resin, wherein the anhydrous gypsum powder of type II is contained in an amount of 55% by mass or more and 65% by mass or less of the total mass of the resin processing material, the thermoplastic resin is contained in an amount of 35% by mass or more and 45% by mass or less of the total mass of the resin processing material, and the particle size distribution of the anhydrous gypsum powder of type II is such that 80% or more of the components have a particle size of 10 μm or less.

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

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

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

5. The resin processed 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 material according to claim 1 or 2, wherein the type II anhydrous gypsum powder is in the form of non-acicular and non-plate-like crystals, and the type II anhydrous gypsum component accounts for 90% by mass or more of the total.

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

8. The resin 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 or more and 5% by mass or less based on the total mass of the resin material.

9. The resin material according to claim 1 or 8, further comprising at least one of pigments and dyes in an amount of 0.1% by mass or more and 5% by mass or less with respect to the total mass of the resin material.

10. The process comprises: a first grinding step of grinding a waste gypsum board containing a gypsum core and paper attached to the gypsum core, and separating the intermediate gypsum powder obtained by grinding the gypsum core from the paper; a heating step of heating the intermediate gypsum powder to make type II anhydrous gypsum and burning off any residue containing paper and / or plastic in the intermediate gypsum powder; a second grinding step of grinding the intermediate gypsum powder after the heating step into fine gypsum powder; and a raw material production step of mixing the fine gypsum powder as type II anhydrous gypsum powder with a thermoplastic resin to produce a raw material for resin processing, wherein 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. A method for producing a resin processed material using waste gypsum board, wherein in the raw material preparation step, the anhydrous gypsum powder of type II is mixed with the thermoplastic resin such that the anhydrous gypsum powder is contained in an amount of 55% by mass or more and 65% by mass or less relative to the total mass of the resin processed material, and the thermoplastic resin is contained in an amount of 35% by mass or more and 45% by mass or less relative to the total mass of the resin processed material.

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

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