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 resin processed products containing type II anhydrous gypsum and a method for producing the same.

Background Art

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

[0003] Waste gypsum board can be recycled. Specifically, the gypsum and paper removed from waste gypsum board can be recycled as recycled resources. When recycling, at present, for example, most of the gypsum removed from waste gypsum board is used for the remanufacture of 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 amount of waste gypsum board generated. In reality, most waste gypsum boards are 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] The landfill treatment of waste gypsum board is currently carried out at a managed industrial waste disposal site. However, industrial waste disposal sites have limitations in securing land, and it is desirable to avoid their operation as much as possible in order to suppress environmental impact and health hazards.

[0005] Due to the above circumstances, it is desired to realize an environment in which as many waste gypsum boards as possible can be recycled. For these reasons, various technologies related to the treatment of waste gypsum board have been proposed conventionally, and are disclosed, for example, in Patent Documents 1 to 4 and the like.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0007] The inventor of the present case considered that the reasons why the improvement and popularization of the recycling environment of waste gypsum board are not progressing as desired are as follows (1) to (4). (1) The main uses of the gypsum taken out from waste gypsum board (remanufacture of gypsum board and solidifying material) are currently very limited. That is, the market is limited, and many operators are not willing to enter. (2) The gypsum taken out from waste gypsum board is generally required to be so-called dihydrate gypsum and in the state of acicular crystals. That is, such characteristics or properties impose restrictions on the reuse applications and make it difficult to expand the market (applications). (3) The gypsum taken out from the current waste gypsum board has some foreign substances such as sand and plastic remaining. Such foreign substances may cause undesirable effects, for example, on the environment and impose restrictions on the applications. (4) Recycling waste gypsum board requires a lot of costs and labor. This point has become an entry barrier.

[0008] Then, based on the above circumstances, the inventors of the present case conducted intensive studies and found that the applications of the gypsum taken out from waste gypsum board can be expanded by devising the properties and manufacturing process of the gypsum.

[0009] Specifically, the inventors of the present case found that by making the gypsum taken out from waste gypsum board into fine anhydrous gypsum, particularly type II anhydrous gypsum, and appropriately removing impurities, the applications of the gypsum taken out from waste gypsum board can be significantly expanded.

[0010] More specifically, high-purity and fine Type II anhydrous gypsum can be used, for example, as a raw material for resin processed products with excellent processing accuracy considering environmental issues. Since such a raw material for resin processed products containing gypsum has no or few impurities, it can be expected to be utilized in the civil field.

[0011] And, the inventor of the present invention considered that in order to enable the raw material for resin processed products to be used in various molding processes (die processing) and further expand its uses, it would be beneficial to produce a raw material for resin processed products by mixing Type II anhydrous gypsum with a thermoplastic resin. Resin processed products formed from such a raw material for resin processed products have an advantage in that their strength can be improved by Type II anhydrous gypsum compared to, for example, processed products consisting only of a thermoplastic resin. Above all, the use of recycled materials has great significance in the current situation where the severity of environmental problems is increasing.

[0012] However, since Type II anhydrous gypsum does not change its form even when heated to the temperature at which the thermoplastic resin melts, it impairs the fluidity of the thermoplastic resin during molding, and proper processing cannot be performed depending on the content of Type II anhydrous gypsum. In addition, Type II anhydrous gypsum can cause roughness on the surface of the processed product, resulting in restrictions on its uses. Also, depending on the content of Type II anhydrous gypsum, although the strength is good, the toughness may become poor, etc., which can also cause restrictions on its uses.

[0013] On the other hand, by reducing the content of Type II anhydrous gypsum, the problem of fluidity during molding can be solved. However, the strength of the completed processed product decreases, and the significance of using recycled materials is lost, and the appeal for environmental issues is lost.

[0014] From the above viewpoints, the inventor of the present invention has earnestly studied a raw material for resin processed products containing Type II anhydrous gypsum and a thermoplastic resin that can obtain the advantage of improving the strength of molded products by Type II anhydrous gypsum, suppress the decrease in toughness, and ensure suitable fluidity during molding.

[0015] The present invention was conceived from the above background, and aims to provide a resin processed material raw material and a manufacturing method thereof that can form a resin processed material with good processing accuracy by ensuring suitable fluidity during the molding of the resin processed material, and can ensure good strength and toughness.

Means for Solving the Problems

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

[0017] [1] A resin processed material raw material containing 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 based on the total mass of the resin processed material raw material, wherein 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 material raw material, and the type II anhydrous gypsum powder is a resin processed material raw material in which 80% or more of the components have a particle diameter of 10 μm or less in the particle size distribution.

[0018] [2] A first pulverization step of pulverizing a waste gypsum board containing a gypsum core material and paper attached to the gypsum core material, and separating the pulverized intermediate gypsum powder of the gypsum core material from the paper, a heating step of heating the intermediate gypsum powder to form type II anhydrous gypsum and burning off residues containing paper and / or plastic contained in the intermediate gypsum powder, a second pulverization step of pulverizing the intermediate gypsum powder after the heating step into fine gypsum powder, and a raw material production step of producing a resin processed material 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 is such that 80% or more of the components have a particle diameter of 10 μm or less in the particle size distribution, In the raw material preparation step, the type II anhydrous gypsum powder 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 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. The type II anhydrous gypsum powder and the thermoplastic resin are mixed to produce a resin processed product raw material using waste gypsum board.

Advantages of the Invention

[0019] According to the present invention, a resin processed product having good processing accuracy can be formed by ensuring suitable fluidity during molding, and good strength and toughness can be ensured.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0021] Hereinafter, an embodiment of the present invention will be described.

[0022] <Resin Processed Product Raw Material> The raw material for a resin processed product according to an embodiment of the present invention is a raw material for a resin processed product containing type II anhydrous gypsum powder and a thermoplastic resin. Specifically, in the raw material for a resin processed product according to this embodiment, 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 its total mass, and the thermoplastic resin is contained in an amount of 35% by mass or more and 45% by mass or less based on its total mass. And, the type II anhydrous gypsum powder contained in the raw material for a resin processed product has a particle size of 10 μm or less for 80% or more of the components in the particle size distribution.

[0023] The specific gravity of the type II 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 setting the content ratio of the type II anhydrous gypsum powder to 55% by mass or more and 65% by mass or less, and the content ratio of the thermoplastic resin to 35% by mass or more and 45% by mass or less, the ratio of the volume of the type II anhydrous gypsum powder to the volume of the thermoplastic resin is approximately about 1:2. In this case, when the thermoplastic resin is melted and mixed with the type II anhydrous gypsum powder, each particle of the type II anhydrous gypsum powder can be coated with a thickness of about half of the particle size. Furthermore, since the type II anhydrous gypsum powder has a particle size of 10 μm or less for 80% or more of the components in the particle size distribution, the type II anhydrous gypsum powder is easily dispersed in the thermoplastic resin, and the coating state of the type II anhydrous gypsum powder by the thermoplastic resin is easily formed. Thereby, when the type II anhydrous gypsum powder and the thermoplastic resin are mixed, a sea-island structure in which the thermoplastic resin is the sea phase and the type II anhydrous gypsum powder is the island phase can be preferably formed.

[0024] As a result, according to the resin processed product raw material according to this embodiment, suitable fluidity during the molding of the resin processed product can be ensured. Thereby, the processing accuracy of the resin processed product can be improved. In addition, since more than half of the components in terms of the mass ratio of the resin processed product raw material are hard type II anhydrous gypsum powder, good strength of the resin processed product can be ensured, while sufficient inclusion of the thermoplastic resin can ensure good toughness of the resin processed product. Furthermore, since the particle diameters of many components in the type II anhydrous gypsum powder are 10 μm or less, the surface roughness of the completed resin processed product can be suppressed, and there are also advantages such as relaxation of the restrictions on the use of the resin processed product. Hereinafter, each component of the resin processed product raw material and components that can be selectively added will be described in detail.

[0025] (Type II anhydrous gypsum powder) As described above, the type II anhydrous gypsum powder contained in the resin processed product raw material is such that the particle diameters of 80% or more of the components in the particle size distribution are 10 μm or less. 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 (Microtrac MT3300EXII manufactured by Microtrac Bell Co., Ltd.). As specific measurement conditions, isopropyl alcohol (refractive index 1.38) is selected as the solvent, 1.81 is selected as the refractive index for the particle conditions, transmission is selected as the particle permeability, and non-spherical is selected as the particle shape.

[0026] In addition, the type II anhydrous gypsum powder used in this embodiment is a non-needle crystal and a non-plate crystal. Gypsum is generally a needle crystal and exhibits advantages such as improving the bonding strength with other members by taking advantage of this property. However, the type II anhydrous gypsum powder used in this embodiment is deliberately made into a non-needle crystal and a non-plate crystal, whereby it can be suppressed that the fluidity during molding is adversely affected. The state of a non-needle crystal and a non-plate crystal can be obtained by finely pulverizing the type II anhydrous gypsum powder.

[0027] Moreover, the type-II anhydrous gypsum powder has a type-II anhydrous gypsum component of 90% by mass or more based on the whole. The state where the type-II anhydrous gypsum component in the type-II anhydrous gypsum powder is 90% by mass or more 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 the type-II anhydrous gypsum component in the type-II anhydrous gypsum powder is specified by obtaining the Ca component and the S component by wavelength dispersive fluorescent X-ray analysis and adding them up.

[0028] In the present embodiment, it is assumed that the above type-II anhydrous gypsum powder is obtained from waste gypsum board. Thereby, most of the raw material for resin processed products consists of recycled materials, and the appeal for environmental issues can be ensured. However, the type-II anhydrous gypsum powder does not necessarily have to be obtained from waste gypsum board.

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

[0030] As the thermoplastic resin, preferably, those conforming to JIS K 7210-1:2014 and having a melt flow rate (MFR) measured under the conditions of a temperature of 230°C and a load of 2.16 Kg of 4 g / 10 min or more and 6 g / 10 min or less are used. In the case of such an MFR, suitable fluidity during molding can be ensured, and high strength and toughness can be ensured in the resin processed product after molding. The higher the MFR of the thermoplastic resin, the higher the fluidity of the material during molding. On the other hand, generally, as the molecular weight decreases, the strength and toughness tend to decrease in the resin processed product after molding. An MFR of 4 g / 10 min or more and 6 g / 10 min or less is not necessarily high, but even when mixed with the 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 MFR, ensuring high strength and toughness in the resin processed product after molding, and ease of availability, the thermoplastic resin preferably includes polypropylene, and particularly as polypropylene, it preferably includes 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 less of polypropylene (block polypropylene) based on the total mass of the thermoplastic resin. Polypropylene has a relatively small specific gravity, which is also advantageous from the viewpoint of ensuring fluidity by securing its volume.

[0032] Block polypropylene (block PP) is a material in which EPR (ethylene propylene rubber) is dispersed in polypropylene, and the mechanical strength can be improved by the dispersion of EPR.

[0033] (Other components) The raw material for the resin processed product may be composed only of the type II anhydrous gypsum powder and the thermoplastic resin as described above, or may additionally contain other components. For example, the raw material for the resin processed product 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 can be improved, and the fluidity during molding can be improved. When containing at least one of a lipophilic surfactant and a coupling agent, it is not desirable to have an excessive amount, and the content ratio of at least one of a lipophilic surfactant and a coupling agent may be 0.1% by mass or more and 5% by mass or less based on the total mass of the raw material for the resin processed product.

[0034] Also, the raw material for the resin processed product may contain at least one of a pigment and a dye. Since the inclusion of a pigment and a dye affects the fluidity during molding, the content ratio is preferably 0.1% by mass or more and 5% by mass or less based on the total mass of the raw material for the resin processed product.

[0035] <Manufacturing method> Next, an example of the method for manufacturing the raw material for the resin processed product will be described.

[0036] FIG. 1 shows a schematic configuration of a manufacturing system S used for manufacturing the raw material for the resin processed product. The manufacturing system S includes a first pulverizing and separating device 1, a heating device 10, and a second pulverizing and separating device 20.

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

[0038] The particle size of the intermediate gypsum powder pulverized in the first pulverizing and separating device 1 is not particularly limited, and it may be pulverized in a relatively coarse state (a state where 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, since the treatment by the second pulverizing and separating device 20 performed in the subsequent stage can be carried out smoothly and accurately when the intermediate gypsum powder is finely pulverized in the first pulverizing and separating device 1, it is desirable that the particle size of the intermediate gypsum powder be about 5 mm or less.

[0039] As the first pulverizing and separating device 1, a general gypsum board pulverizing device may be employed. As the first pulverizing and separating device 1, for example, a gypsum board treatment system manufactured by Toowa Kogyo Co., Ltd. or a gypsum board separator manufactured by Hosoda Kikaku Co., Ltd. may be employed. However, the specific configuration of the first pulverizing and separating device 1 is not particularly limited.

[0040] The heating device 10 heats the intermediate gypsum powder pulverized by the first pulverizing and separating device 1. The heating device 10 performs heating in order to heat the intermediate gypsum powder to form type II anhydrous gypsum and burn off the residue containing paper and / or plastic contained in the intermediate gypsum powder.

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

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

[0043] The second pulverizing and separating device 20 is a device that receives and pulverizes the intermediate gypsum powder heated by the heating device 10. In this example, the second pulverizing and separating device 20 is composed of an air-flow type pulverizer having a classification function.

[0044] Specifically, the second pulverizing and separating device 20 includes an inlet 21 for receiving the intermediate gypsum powder, a fine pulverizing section 22 for pulverizing the intermediate gypsum powder received from the inlet 21 into fine gypsum powder, a classification section 23 for separating components having a larger particle diameter than the fine gypsum powder pulverized in the fine pulverizing section 22, a collecting section 24 for collecting the components having the larger particle diameter 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 pulverization unit 22 includes a rotor with blades, and pulverizes the intermediate gypsum powder into a fine state by dividing the intermediate gypsum powder or causing the intermediate gypsum powders to collide with each other by means of a swirling flow generated by the rotating rotor. The classification unit 23 separates the fine gypsum powder pulverized by the fine pulverization unit 22 and the residue containing sand included in the intermediate gypsum powder. In the present embodiment, the classification unit 23 has a structure that forms a clearance that allows the fine gypsum powder pulverized by the fine pulverization unit 22 to pass downstream and restricts the passage of components having a particle size larger than that of the fine gypsum powder downstream. In this structure, the components whose passage is restricted by the classification unit 23 are either pulverized again by the fine pulverization unit 22 or drop off from the fine pulverization unit 22 and are accumulated below the rotor of the fine pulverization unit 22. In particular, the components that cannot be pulverized into fine gypsum powder are sequentially accumulated below the rotor. However, the classification unit 23 may have a structure that, for example, applies air resistance and centrifugal force to move the residue radially outward and discharges the fine gypsum powder in the axial direction of the rotor.

[0046] The type II anhydrous gypsum powder assumed to be used in the present invention has a particle size distribution in which 80% or more of the components have a particle size of 10 μm or less, and it is assumed to be obtained from intermediate gypsum powder. In order to enable such fine pulverization, in the second pulverization and separation device 20, the rotation speed, the classification clearance, the raw material input amount (the input amount of intermediate gypsum powder), the air volume, etc. are adjusted. In the case of the above-described particle size distribution, the particle sizes of many components in the fine gypsum powder are 10 μm or less. Here, the particle size of sand is generally about 20 μm to 2 mm. When pulverization and classification are performed with the intention of the above-described particle size distribution, the residue containing sand can be accurately separated from the fine gypsum powder by the classification unit 23. Thereby, the state in which the residue is mixed into the fine gypsum powder can be suppressed.

[0047] When obtaining the fine gypsum powder with the above particle size distribution, in the classification section 23 of the second pulverizing and separating device 20 in this example, the classification clearance is set 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, and specifically 2 mm in this example. Such a clearance is set to accurately separate the residue containing sand. To efficiently proceed with both refinement and removal of the residue containing sand simultaneously, it is desirable to set the classification clearance 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, and specifically 2 mm in this example. However, the numerical value of the classification clearance is not particularly limited.

[0048] Also, the fine gypsum powder pulverized by the fine pulverizing section 22 of the second pulverizing and separating device 20, which is a pneumatic pulverizer, is likely to become fine granular bodies, losing the form of acicular crystals or plate-like crystals.

[0049] Then, the residue separated in the classification section 23 is collected by the collection section 24 without being circulated like a general pneumatic pulverizer in this example. Thereby, the mixing of the residue in the fine gypsum powder finally taken out from the outlet 25 can be suppressed. However, the residue collected by the collection section 24 also contains a gypsum component, and it may be re-introduced into the inlet 21 in order to effectively utilize it. In this case, it is desirable to remove the sand from the residue and then re-introduce it into the inlet 21. Also, when taking out the fine gypsum powder from the outlet 25, applying vibration to the outlet 25 makes it easier to take out the fine gypsum powder. Although not shown in the figure, a vibration generator is provided at the outlet 25, and vibration is applied at a predetermined cycle.

[0050] As the second pulverizing and separating device 20, various air-flow pulverizers can be employed, and a collecting section 24 is additionally provided. As the second pulverizing and separating device 20, for example, a Selene Miller MKCL8-20 (registered trademark) manufactured by Masayuki Sangyo Co., Ltd. may be used. Note that the second pulverizing and separating device 20 in this example is an air-flow pulverizer having a classification function. However, if type II anhydrous gypsum powder in which 80% or more of the components have a particle size of 10 μm or less can be obtained in the particle size distribution assumed for use in the present invention, other pulverizing devices may be used and do not necessarily have to have a classification function.

[0051] Thereafter, the type II anhydrous gypsum powder as the fine gypsum powder obtained from the second pulverizing and separating device 20 is mixed with the thermoplastic resin. Specifically, the type II anhydrous gypsum powder is contained in an amount of 55% by mass or more and 65% by mass or less, and 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, so that the type II anhydrous gypsum powder and the thermoplastic resin are mixed. At this time, after mixing the type II anhydrous gypsum powder into the melted thermoplastic resin, pellets as the resin processed product raw material may be formed by curing.

[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 type II anhydrous gypsum powder and the thermoplastic resin are mixed in the mixer 31, the mixture is introduced into the extruder 32, and the thermoplastic resin is melted and extruded, for example, in a string shape. Thereafter, after the string-shaped mixture is cooled, it is finely cut by the pelletizer 33 to form pellets as the resin processed product raw material.

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

[0054] FIG. 2 is a flowchart showing the manufacturing procedure of the raw material for the resin processed product by the manufacturing system S. Hereinafter, the manufacturing procedure of the raw material for the resin processed product will be described in detail.

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

[0056] In step S2, a heating step is performed to heat the intermediate gypsum powder obtained in the first pulverization and separation step by the heating device 10 to form type II anhydrous gypsum, and burn off the residue containing 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 step.

[0057] In step S3, a second pulverization and separation step (second pulverization step) is performed to pulverize the intermediate gypsum powder after the heating step and separate the residue. In the second pulverization and separation step, specifically, the intermediate gypsum powder is pulverized into fine gypsum powder by the second pulverization and separation device 20 which is a pneumatic pulverizer, and the residue containing sand contained in the intermediate gypsum powder is separated in the classification section 23 and further collected and separated from the fine gypsum powder.

[0058] In this example, by using a pneumatic pulverizer, in the second pulverization and separation step, foreign matters (residues) are removed simultaneously with the pulverization of the intermediate gypsum powder, so that the target high-purity fine gypsum powder can be efficiently and simply taken out, and the tact time can be significantly reduced compared with the case of using a sieve, for example. Note that in the second pulverization and separation step, pulverization and separation are performed simultaneously, but separation may not be performed.

[0059] Figure 3 shows a SEM image of an example of type II anhydrous gypsum powder, which is fine gypsum powder generated by the manufacturing system S (generated by the above step S3). In Figure 3, it can be seen that the fine gypsum powder is composed of non-needle-shaped and non-plate-shaped crystals and is in the form of fine granular bodies. Also, as is clear from comparison with the scale in Figure 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 is performed under two different first and second operation patterns. The difference between the first operation pattern and the second operation pattern is the input amount of intermediate gypsum powder, with the former being 2.00 Kg and the latter being 3.46 Kg. Due to the difference in the input amount, there is a difference in the input amount per unit time between the first operation pattern and the second operation pattern.

[0061]

Table 1

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

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

[0064]

Table 2

[0065] From the results in Table 2, it can be seen that the total value of the Ca component and the S component is 90.8 mass%, indicating that the gypsum component is contained with high purity.

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

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

[0068] The resin processed product raw material according to the present embodiment described above can ensure suitable fluidity during the molding of the resin processed product. As a result, the processing accuracy of the resin processed product can be improved. Further, since more than half of the components in the resin processed product raw material by mass ratio are hard type II anhydrous gypsum powder, good strength of the resin processed product can be ensured, while sufficient inclusion of the thermoplastic resin can ensure good toughness of the resin processed product. Furthermore, since the particle diameters of many components in the type II anhydrous gypsum powder are 10 μm or less, the surface roughness of the completed resin processed product can be suppressed, and there are also advantages such as relaxation of the restrictions on the use of the resin processed product.

Explanation of Reference Numerals

[0069] 1... First pulverization and separation device, 2... Hopper, 3... Pulverization section, 4... Separation section, 10... Heating device, 20... Second pulverization and separation device, 21... Inlet, 22... Fine pulverization section, 23... Classification section, 24... Collection 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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