Method for producing powder, powder, and resin

Abstract

The present invention provides a method for producing a powder, a powder, and a resin that can exhibit a higher VOC adsorption effect. [Solution] The method for producing the powder comprises the steps of: crushing a porous material such as a sea urchin shell, which has many micropores filled with organic matter and is mainly composed of calcium carbonate; and firing the pulverized material obtained from the crushing step at a temperature of 680°C to 710°C for 2 to 6 hours. After that, the powder is kneaded into a resin to create a resin body.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a powder, the powder itself, and a resin. [Background technology]

[0002] Conventionally, a method for producing calcium oxide powder has been proposed, which involves crushing and calcining sea urchin shells to obtain calcium oxide powder (see Patent Document 1). In this method, sea urchin shells are calcined at a temperature of 700°C or lower, then calcined again at a temperature of 1000 to 1100°C to convert the calcium carbonate, the main component of sea urchin shells, into calcium oxide, and then spread thinly in the air and left to disintegrate into a fine powder. Sea urchin shells are porous bodies with numerous micropores, and organic matter is embedded in each micropore. In Patent Document 1, the organic matter is removed by calcination at least to 1000 to 1100°C. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2009-126777 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The inventors of this case have been studying the adsorption effect of VOCs (Volatile Organic Compounds) such as calcium oxide. They have found that in order to enhance the VOC adsorption effect, it is necessary to remove organic matter by calcining sea urchin shells, as well as to increase the specific surface area of ​​powders such as calcium oxide.

[0005] However, although the manufacturing method described in Patent Document 1 yields calcium oxide powder, The specific surface area was not particularly large, and it was difficult to say that a sufficient VOC adsorption effect was achieved.

[0006] The present invention was made to solve these conventional problems, and its objective is to provide a method for producing a powder, a powder, and a resin that can exhibit a higher VOC adsorption effect. [Means for solving the problem]

[0007] To solve the aforementioned problems, the method for producing a powder according to the present disclosure comprises a first step of pulverizing a porous body having a large number of micropores filled with organic matter, with calcium carbonate as the main component, and a second step of calcining the pulverized material obtained by the pulverization in the first step at a temperature of 680°C to 710°C for 2 hours to 6 hours.

[0008] Furthermore, the powder relating to this disclosure is a powder having an average particle size of 5.0 μm or more and 22.5 μm or less, with a calcium oxide content of 80 wt% or more, and a specific surface area of ​​1.0 m² measured by the nitrogen adsorption method (BET method). 2 The specific surface area is 1.0 m² or more, either containing 50 wt% or more of calcium carbonate relative to the total, and measured by the nitrogen adsorption method (BET method). 2 It is 1 / g or more.

[0009] Furthermore, the resin body according to this disclosure is formed by kneading the above powder into a resin. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a method for producing a powder, a powder, and a resin that can exhibit a higher VOC adsorption effect. [Brief explanation of the drawing]

[0011] [Figure 1] This is a diagram showing a resin body according to the first embodiment. [Figure 2] This is a scanning electron microscope (SEM) image of the powder material, which is a part of the composition shown in Figure 1. [Figure 3] Figure 2 is a magnified view of a portion of the photograph shown. [Figure 4] It is a graph showing the pore size distribution of the powder shown in FIG. 1. [Figure 5] It is a process diagram showing a method for manufacturing a resin body according to the first embodiment. [Figure 6] It is a configuration diagram showing a resin body according to the second embodiment. [Figure 7] It is a graph showing the pore size distribution of the powder shown in FIG. 6. [Figure 8] It is a process diagram showing a method for manufacturing a resin body according to the second embodiment.

Embodiments for Carrying out the Invention

[0012] Hereinafter, the present invention will be described in accordance with preferred embodiments. Note that the present invention is not limited to the embodiments shown below, and can be appropriately changed without departing from the spirit of the present invention. Also, in the embodiments shown below, there are some places where the illustration and description of some configurations are omitted. However, it goes without saying that well-known or well-understood technologies are appropriately applied within the range where there is no contradiction with the content described below regarding the details of the omitted technologies.

[0013] FIG. 1 is a configuration diagram showing a resin body according to the first embodiment. Since there are a large number of reference numerals 20 in FIG. 1, only a part of them will be indicated by reference numerals. As shown in FIG. 1, the resin body 1 includes a resin 10 and a powder body 20. In the first embodiment, the resin 10 is not particularly limited, but a resin (for example, polypropylene) that does not contain additives other than antioxidants is preferred.

[0014] The powder 20 has an average particle size of 5.0 μm or more and 22.5 μm or less. The proportion of calcium oxide in the powder 20 is 80 wt% or more with respect to the whole, and most of the remainder is, for example, calcium carbonate. The average particle size is obtained by observing the particles with a scanning electron microscope (SEM), measuring the diameters of 20 randomly selected particles, and adopting the average thereof. The proportions of calcium oxide and calcium carbonate are calculated from the intensity ratio of the strongest peaks of calcium oxide and calcium carbonate by measuring each sample by the powder X-ray diffraction method.

[0015] In addition, the powder 20 has a specific surface area measured by the nitrogen adsorption method (BET method) of 1.0 m 2 / g or more, and preferably has a specific surface area of 2.50 m 2 / g or more. The specific surface area measured by the BET method is usually obtained by enclosing the measurement target particles in a system at a vacuum and liquid nitrogen temperature, and then detecting the amount of nitrogen adsorbed by the particles when the nitrogen vapor pressure in the system is gradually increased, and can be said to reflect the actual surface area of the sample.

[0016] FIG. 2 is a photograph of a scanning electron microscope (SEM) showing the state of the powder 20, which is a partial configuration of FIG. 1, before pulverization, and FIG. 3 is a partially enlarged photograph of the photograph shown in FIG. 2. Since there are a large number of reference signs SK and CR in FIG. 2 or FIG. 3, only a part thereof is indicated by the reference signs. The electron microscope used was JSM-6010 manufactured by JEOL Ltd.

[0017] The powder 20 is obtained by pulverizing the structure ST shown in FIG. 2. This structure ST is obtained by firing a sea urchin shell. The sea urchin shell is a porous body in a state where an organic substance fills fine pores. The type of sea urchin used as the raw material is not particularly limited, and for example, purple sea urchin or the like may be used.

[0018] The structure ST is made of sea urchin shells, and as a result of calcining, organic matter in the micropores is removed, resulting in a skeleton SK that forms numerous micropores H. The skeleton SK has a width of approximately 5 μm (more specifically, for example, between 3 μm and 7 μm), and the pore diameter of the numerous micropores H is approximately between 2.0 μm and 31.3 μm. The pore volume of the numerous micropores H, calculated by the BET method, is 8.5 × 10⁻⁶. -3 cm 3 / g or more 39.2×10 -3 cm 3 The density is less than or equal to / g, and the pore size peak is between 2.0 nm and 50.0 nm. Furthermore, as shown in Figure 3, the structure ST has numerous cracks CR in the framework SK. The length of the cracks CR is, for example, between 30 nm and 170 nm.

[0019] The structure ST described above has numerous micropores H and numerous cracks CR. Therefore, even in its crushed state, the structure ST has a large specific surface area, and since the proportion of calcium oxide is 80 wt% or more, it can exhibit a higher VOC adsorption effect.

[0020] Figure 4 is a graph showing the pore size distribution of powder 20 shown in Figure 1. When the pore size distribution of powder 20 was evaluated by the GCMC method, as shown in Figure 4, the pore size peak was around 10 nm (9.5 nm to 11.0 nm), and was at least 1 nm or larger.

[0021] Figure 5 is a process diagram showing the manufacturing method of the resin body 1 according to the first embodiment. As shown in Figure 5, in manufacturing the resin body 1 according to the first embodiment, the sea urchin shell is first dried (S1). In this step, for example, it is dried for 24 hours in a temperature environment of 80°C.

[0022] Next, coarse grinding is performed (S2: first step). In this step, the material is ground using a granulator (SPCII-200, Harmo Co., Ltd.) to an average particle size of approximately 3 mm. After that, fine grinding is performed (S3: first step). In this step, for example, a high-speed mill (HS-20, manufactured by Labonect Co., Ltd.) is used to obtain a pulverized material with an average particle size of 5.0 μm to 22.5 μm.

[0023] Next, firing takes place (S4: Second step). In this step, the finely ground material is placed in a crucible and fired in an electric furnace. The firing temperature is between 680°C and 710°C. The firing time is between 2 hours and 6 hours. The firing is carried out in an air atmosphere.

[0024] Here, if the firing temperature is less than 680°C or the firing time is less than 2 hours, the insufficient temperature and time will make it difficult for cracks CR to form in the powder 20. Also, if the firing temperature exceeds 710°C or the firing time exceeds 6 hours, the cracks CR in the powder 20 will be filled in by sintering. Therefore, by firing at a temperature between 680°C and 710°C and for a time between 2 hours and 6 hours, it is possible to properly form cracks CR in the powder 20, increase the specific surface area, and exhibit a higher VOC adsorption effect.

[0025] Furthermore, sea urchin shells have organic matter filling their micropores (H). The calcination process also removes this organic matter. In addition, the heat treatment causes the calcium carbonate, the main component of sea urchin shells, to decompose into calcium oxide. During this process, the sea urchin shells shrink. This shrinkage makes them more susceptible to crack formation (CR). Other factors such as the vaporization and detachment of organic matter, and the destabilization of the calcium carbonate crystal structure by various elements also make them more prone to crack formation (CR).

[0026] Thereafter, kneading is performed (S5). In this step, the powder body 20 is kneaded into the resin 10. As a result, the resin body 1 with a reduced amount of resin 10 used can be obtained. Moreover, since the powder body 20 is kneaded, the resin body 1 that exhibits the VOC adsorption effect can be obtained.

[0027] In this way, the manufacturing method of the powder body 20 according to the first embodiment is fired at a temperature of 680°C or higher and 710°C or lower for 2 hours or more. Therefore, it is avoided that cracks CR are hardly formed in the powder body 20 as in the case of firing at a temperature lower than 680°C. Also, the possibility that the cracks CR in the powder body 20 are filled by sintering as in the case of firing exceeding 710°C or firing exceeding 6 hours can be reduced. Therefore, cracks CR can be appropriately formed in the powder body 20, the specific surface area can be increased, and a higher VOC adsorption effect can be exhibited.

[0028] Further, the powder body 20 according to the first embodiment has an average particle size of 5.0 μm or more and 22.5 μm or less, the ratio of calcium oxide to the whole is 80 wt% or more, and the specific surface area measured by the BET method is 1.0 m 2 / g or more. Therefore, it is possible to provide the powder body 20 that can increase the specific surface area and exhibit a higher VOC adsorption effect.

[0029] Also, the resin body 1 according to the first embodiment is formed by kneading the powder body 20 into the resin 10. As a result, the powder body 20 is added to the resin 10 to reduce the resin amount, and the resin body 1 with a further reduced resin amount can be provided.

[0030] Next, the manufacturing method of the powder body, the powder body, and the resin body according to the second embodiment will be described. The manufacturing method of the powder body, the powder body, and the resin body according to the second embodiment are the same as those of the first embodiment, but are partially different. Hereinafter, the differences from the first embodiment will be described.

[0031] Figure 6 is a diagram showing the resin body according to the second embodiment. Unlike the first embodiment, the powder 30 according to the second embodiment shown in Figure 6 has a calcium carbonate content of 50 wt% or more of the total, with the majority of the remainder being, for example, calcium oxide. Preferably, the calcium carbonate content of the powder 30 is 70 wt% or more of the total. Calcium carbonate exhibits a VOC adsorption effect similar to calcium oxide.

[0032] Furthermore, the powder 30 has a specific surface area of ​​1.0 m² as measured by the BET method. 2 The amount is 1 / g or more, and preferably the specific surface area is 1.30 m². 2 This refers to anything that is 1 / g or more.

[0033] Such a powder 30 can be obtained by further calcining the powder 20 shown in the first embodiment in a carbon dioxide atmosphere. Specifically, the powder 30 can be obtained by calcining the powder 20 according to the first embodiment in an atmosphere with a carbon dioxide concentration of 50% or more at a temperature of 450°C to 710°C for 2 hours to 6 hours.

[0034] Here, calcium oxide can be converted back to calcium carbonate by calcination in a carbon dioxide atmosphere. Therefore, the powder 30 has a calcium carbonate content of 50 wt% or more. Furthermore, when calcium oxide is kneaded into the resin 10, it reacts with additives other than the antioxidant in the resin 10 to generate acetaldehyde. However, calcium carbonate does not generate acetaldehyde, and the resin body 2 according to the second embodiment can suppress the generation of acetaldehyde more than the resin body 1 according to the first embodiment.

[0035] Furthermore, when sea urchin shells (calcium carbonate) are calcined and thermal decomposition generates calcium oxide, shrinkage occurs, making it easier for cracks (CR) to form. On the other hand, when calcium oxide is converted back to calcium carbonate, crystal growth (expansion) tends to fill in some of the cracks (CR). Therefore, powder 30 has a specific surface area of ​​1.0 m² as measured by the BET method. 2 It is 1.30m or more per gram, preferably 1.30m2 It is stated to be 1g or more.

[0036] Here, we consider a case where sea urchin shells are calcined once in a carbon dioxide atmosphere (concentration of 50% or more) instead of in an air atmosphere. In this case, calcium oxide is less likely to be generated, and calcium carbonate powder can be obtained. However, according to the inventors' research, in this case, the specific surface area becomes smaller, for example, 0.293 m². 2 It was found that the amount would be around / g. Therefore, in order to suppress the generation of acetaldehyde, for example, while increasing the adsorption effect of VOCs, it is preferable to calcine in an air atmosphere and then calcine again in a carbon dioxide atmosphere.

[0037] Figure 7 is a graph showing the pore size distribution of the powder 30 shown in Figure 6. When the pore size distribution of the powder 30 was evaluated by the GCMC method, the pore size peak was less than 1 nm, as shown in Figure 7. This means that the powder 30 according to the second embodiment expanded (crystal growth) compared to the powder 20 according to the first embodiment, filling in some of the cracks CR, and as a result the specific surface area became smaller. However, as mentioned above, the powder 30 according to the second embodiment, which has calcium carbonate as its main component, can suppress the generation of acetaldehyde when kneaded into the resin 10. Furthermore, compared to the case where sea urchin shells are calcined once in a carbon dioxide atmosphere without being calcined in an air atmosphere, the specific surface area measured by the BET method for the powder 30 according to the second embodiment is 1.0 m² when calcined in an air atmosphere. 2 It can be 1g or more.

[0038] Figure 8 is a process diagram showing the manufacturing method of the resin body 2 according to the second embodiment. As shown in Figure 8, first the steps S1 to S4 shown in Figure 5 are carried out. This first yields a powder body 20 mainly composed of calcium oxide.

[0039] Next, a second firing is performed (S6: third step). In this step, the powder 20 is fired in an atmosphere with a carbon dioxide concentration of 50% or more at a temperature of 450°C to 710°C for 2 to 6 hours. This process converts calcium oxide back to calcium carbonate, yielding powder 30. The conversion of calcium oxide back to calcium carbonate by firing at 450°C or higher is also described in the Ceramics Industry Journal, Vol. 89, No. 1034, pp. 568-571, 1981. Although this process causes crystal growth and leads to a decrease in specific surface area, a certain level of specific surface area can be secured because firing in an atmospheric environment is performed once in step S4. Furthermore, by performing the firing at 710°C or lower and for 6 hours or less, it is possible to suppress the situation in which the cracks CR that have been formed are filled in by sintering.

[0040] Subsequently, mixing takes place (S5). In this process, the powder 30 is mixed into the resin 10. In particular, since the powder 30 is mainly composed of calcium carbonate, the generation of acetaldehyde is suppressed. As a result, it is not necessary to use powder 20 that can only be mixed into a specific resin 10 in order to suppress the generation of acetaldehyde, and the range of resin 10 that can be selected can be broadened.

[0041] Thus, the method for producing the powder 30 according to the second embodiment involves calcining the obtained powder 20 at a temperature of 450°C or higher for 2 hours or more in an atmosphere with a carbon dioxide concentration of 50% or higher. Therefore, the calcium oxide obtained by calcination in an atmospheric environment can be converted to calcium carbonate. Here, calcium carbonate can obtain the same VOC adsorption effect as calcium oxide. Furthermore, when calcium oxide is kneaded into a specific resin 10, it reacts with some additives to generate acetaldehyde. However, calcium carbonate generates less acetaldehyde, and therefore allows for a wider range of resin 10 to be selected during kneading. Thus, the range of resins 10 that can be kneaded can be broadened.

[0042] Furthermore, the powder 30 has an average particle size of 5.0 μm or more and 22.5 μm or less, a calcium carbonate content of 50 wt% or more, and a specific surface area of ​​1.0 m² as measured by the BET method. 2 It is 1 / g or more. Therefore, while calcium carbonate is the main component, the specific surface area can be increased. As a result, it is possible to use calcium carbonate, which does not easily generate acetaldehyde, as the main component, and to exhibit VOC adsorption effect.

[0043] Although the present invention has been described above based on embodiments, the present invention is not limited to the above embodiments, and modifications may be made without departing from the spirit of the invention, and if possible, publicly known or well-known technologies may be combined.

[0044] For example, the above embodiment described a method for producing powders 20 and 30 from sea urchin shells. However, the powders are not limited to sea urchin shells and may be produced from other natural materials (for example, coral skeletons) that have a porous structure containing calcium carbonate, similar to sea urchin shells, and that contain organic matter within the porous structure. [Explanation of Symbols]

[0045] 1,2: Resin body 10: Resin 20,30: Powder CR: Crack H: Micropore

Claims

1. The first step involves crushing a porous material that has numerous micropores filled with organic matter, with calcium carbonate as the main component. A second step involves firing the pulverized material obtained by the first step at a temperature of 680°C to 710°C for 2 hours to 6 hours. A method for producing a powder, characterized by comprising the following:

2. The process further comprises a third step in which the powder obtained in the second step is calcined in an atmosphere with a carbon dioxide concentration of 50% or more at a temperature of 450°C to 710°C for 2 hours to 6 hours. A method for producing a powder according to feature 1.

3. A powder having an average particle size of 5.0 μm or more and 22.5 μm or less, The calcium oxide content is 80 wt% or more of the total, and the specific surface area measured by the BET method is 1.0 m². ２ / g or more A powder characterized by the following features.

4. A powder having an average particle size of 5.0 μm or more and 22.5 μm or less, The proportion of calcium carbonate to the total is 50 wt% or more, and the specific surface area measured by the BET method is 1.0 m². ２ / g or more A powder characterized by the following features.

5. The powder according to either claim 3 or claim 4 is kneaded into a resin to form the product. A resin body characterized by the following features.

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