JP2017000069A - Foamed resin, resin molded body, laminated resin molded body, sound absorption material and water absorption material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing method facilitating pulverization of foamed resin such as foamed urethane having independent bubbles, and to provide foamed resin having novel characteristics obtained by the processing method.SOLUTION: The foamed resin is provided that has structure in which at least a part of independent bubbles are connected with each other by action of a microorganism, and that has an average particle diameter of 2000 μm or more and 8000 μm or less, or an average particle diameter of 50 μm or more and 1000 μm or less. It is preferable that the foamed resin is urethane, and it is preferable that the microorganism is a microorganism that belongs to genus Streptomyces having urethane decomposing ability.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a foamed resin, and more particularly to a foamed resin subjected to a decomposition treatment using microorganisms, and a pulverized product, a water absorbing material and a sound absorbing material using the same.

  Polyurethane is a polymer having a urethane bond and is also called urethane resin. Polyurethane is gradually decomposed under the influence of moisture hydrolysis, nitrogen oxides (NOx) in the air, salinity, ultraviolet rays, heat, microorganisms, etc., and produces compounds harmful to human bodies and aquatic organisms. Since the leaked polyurethane may cause enormous environmental pollution, it is usually collected by taking preventive measures such as adsorbing it to earth and sand, surrounding it, etc. and sealing it in a container. A recycling system has also been developed for polyurethane, but about 40% of waste polyurethane is still landfilled.

  The inventors found a novel microorganism having adsorption ability and resolution for urethane from soil and filed a patent application (Patent Document 1). The microorganism was found to be a novel actinomycete belonging to the genus Streptomyces from mycological properties and DNA analysis. Since this microorganism has an adsorptivity to urethane, it can bind and agglomerate urethane particles dispersed in water to effectively remove (adsorb and purify) urethane.

JP 2010-220610 A

  Although the microorganism described in Patent Document 1 has an adsorption ability and resolution for urethane, it is necessary to further improve the decomposition rate of urethane for industrial use, and there is room for improvement in that respect.

By the way, as urethane, an elastic body and a material having high viscoelasticity, such as soft polyurethane, are known, but it has been very difficult to pulverize such polyurethane at room temperature. In particular, polyurethane having independent bubbles has high elasticity and mechanical strength, and is more difficult to process than a foam in which bubbles are communicated.
As a method for powderizing such urethane foam, there is known a method of pulverizing after solidifying by freezing using liquid nitrogen. However, such a method is not practical because the equipment becomes large and the running cost increases.

  Then, this invention aims at providing the processing method for making it easy to grind foaming resin like foaming urethane which has an independent cell, and providing the foaming resin which has a new characteristic obtained by the processing method concerned. To do.

  As a result of intensive investigations by the present inventors to solve the above-described problems, at least some of the bubbles are connected to each other by causing microorganisms to act on the foamed resin having independent bubbles, and further to a predetermined particle size. Was found to be effective, and the present invention was completed.

That is, the present invention adopts the following configuration.
(1) A foamed resin characterized by having a structure in which at least some of the independent bubbles are linked by the action of microorganisms and having an average particle size of 2000 μm or more and 8000 μm or less.
(2) A foamed resin having a structure in which at least some of the independent bubbles are linked by the action of microorganisms, and an average particle size of 50 μm or more and 1000 μm or less.
(3) The foamed resin as described in (1) or (2) above, wherein the foamed resin is urethane.
(4) The foamed resin according to any one of (1) to (3) above, wherein the microorganism is a microorganism belonging to the genus Streptomyces having urethane decomposability.
(5) A resin molded product obtained by molding the foamed resin according to (1) and / or (2).
(6) A laminated resin molded article comprising at least one foamed resin molded article obtained by molding the foamed resin according to (1) and / or (2) into a layer.
(7) Use of the foamed resin according to any one of (1) to (4) above, the resin molded body according to (5) above, or the laminated resin molded body according to (6) above. Characteristic sound absorbing material.
(8) The foamed resin according to any one of (1) to (4) above, the resin molded body according to (5) above, or the laminated resin molded body according to (6) above is used. Features a water-absorbing material.

  According to the present invention, it is possible to provide a foamed resin having characteristics as a new material having both characteristics of a foamed resin having independent bubbles and a foamed resin having continuous bubbles. Since the foamed resin has a predetermined particle size, it can exhibit characteristics excellent in water absorption and sound absorption.

(A) It is the microscope picture which observed the mode of the foaming cell before making microorganisms act on urethane foam. (B) It is the microscope picture which observed the mode of the foaming cell after making microorganisms act on urethane foam. It is a photograph which shows the external appearance of the foamed resin whose average particle diameter is 2000 micrometers or more and 8000 micrometers or less. It is a photograph which shows the external appearance of the foamed resin whose average particle diameter is 50 micrometers or more and 1000 micrometers or less. It is the microscope picture which observed the surface of the foaming resin whose average particle diameter is 300 micrometers. It is a photograph which shows an example of the external appearance of the resin molding which shape | molded the foaming resin whose average particle diameter is 5000 micrometers. It is a photograph which shows an example of the external appearance of the resin molding which shape | molded the foaming resin whose average particle diameter is 300 micrometers. It is a graph showing the result of the sound absorption rate in the high frequency area | region of the foamed resin measured in the Example. It is a graph showing the result of the sound absorption rate in the low frequency area | region of the foamed resin measured in the Example. It is a graph showing the result of the sound absorption coefficient of the resin molding measured in the Example. It is a graph which shows the result of the water absorption of the resin molding measured in the Example. It is a graph which shows the result of the water retention of the resin molding measured in the Example.

[Foamed resin]
The foamed resin according to the present invention has a structure in which at least some independent bubbles are connected by the action of microorganisms, and has a predetermined particle size. As a result, a foamed resin having characteristics as a new material having both characteristics of a foamed resin having independent bubbles and a foamed resin having continuous bubbles can be obtained.

For example, when the average particle diameter of the foamed resin having a structure in which at least some of the independent bubbles are linked by the action of microorganisms is 2000 μm or more and 8000 μm or less, it can be preferably used as a sound absorbing material or a water absorbing material. In particular, a resin molded body molded using the foamed resin having an average particle diameter of 3000 μm or more and 6000 μm or less has a sound absorption coefficient superior to that of a conventional sound absorbing material in a low frequency region. In order to produce a foamed resin molded article having an excellent sound absorption coefficient in a low frequency region, the average particle diameter of the foamed resin is more preferably 4000 μm or more and 5000 μm or less.
In the present invention, the average particle diameter of the foamed resin refers to the median diameter of the volume average particle diameter.

  Further, a foamed resin having a structure in which at least some of the independent bubbles are connected by the action of microorganisms can be preferably used as a sound absorbing material or a water absorbing material even when the average particle size is 50 μm or more and 1000 μm or less. . A foamed resin having an average particle size of 50 μm or more and 1000 μm or less exhibits superior properties in terms of sound absorption rate, water absorption, and water retention in a high frequency range, compared to those having an average particle size of 2000 μm or more and 8000 μm or less. To do. In addition, a resin molded body formed using a foamed resin having an average particle diameter of 50 μm or more and 1000 μm or less also has excellent sound absorption coefficient in a low frequency region. In order to produce a foamed resin molded article excellent in water retention, the average particle diameter is more preferably 100 μm or more and 600 μm or less, and further preferably 200 μm or more and 500 μm or less.

The foamed resin according to the present invention can be obtained by pulverizing a foamed resin having independent bubbles to a predetermined particle size after allowing a microorganism having a resolution to act on the foamed resin. . In FIG. 1, the microscope observation photograph of the cross section of the foamed resin which has the independent bubble before and behind making microorganisms act is shown. FIG. 1 (A) shows a state before the microorganism is made to act, and FIG. 1 (B) shows a state after the microorganism is made to act.
When a microorganism having resolution is allowed to act on a foamed resin having independent bubbles, fine cavities of about 1 μm to 10 μm are formed on the wall surfaces of the bubbles. As the decomposition action by the microorganisms progresses, the independent bubbles are connected by the fine cavities. Accordingly, the foamed resin after the action of microorganisms exhibits both characteristics of the foamed resin having bubbles communicated with the foamed resin having independent bubbles.

Since the foamed resin having a structure in which at least some of the independent bubbles are connected by the action of microorganisms has many starting points that break when pulverized, it can be easily pulverized to a desired particle size. FIG. 2 shows a photograph of the particulate foamed resin having an average particle diameter of 2000 μm or more and 8000 μm or less. FIG. 3 shows a photograph of a powdery foamed resin having an average particle size of 50 μm or more and 1000 μm or less.
The method of pulverizing the foamed resin after the action of microorganisms is not particularly limited, and may be appropriately selected depending on the purpose. For example, when the average particle size of the foamed resin is 2000 μm or more and 8000 μm or less, it may be pulverized by a cutting mill or the like. Moreover, what is necessary is just to grind | pulverize, for example by the method using a centrifugal type grinder, etc., when making the average particle diameter of a foamed resin into 50 micrometers or more and 1000 micrometers or less.

  As shown in FIG. 1 (B), the diameter of the fine cavity formed on the wall surface of the bubble when the microorganism is allowed to act on the foamed resin having independent bubbles is about 1 to 10 μm, and the size of the diameter is constant. Not done. However, if the foamed resin after the action of microorganisms is made into a powder having an average particle size of 1000 μm or less, the diameter of the fine cavities can be made uniform to a size of about 1 μm. This is because when the foamed resin is pulverized, it breaks starting from a portion of a fine cavity having a relatively large aperture. As a result, the above-mentioned foamed resin having a particle size of 50 μm or more and 1000 μm or less has a constant microcavity and more stable material characteristics. FIG. 4 shows a micrograph of the surface of the foamed resin having an average particle size of 300 μm.

  In addition, it is very difficult to pulverize a conventional foamed resin having independent bubbles. For example, when the foamed resin is frozen and solidified and pulverized, it costs nearly 100,000 yen per kg and is not practical. In contrast, a foamed resin having a structure in which at least some independent bubbles are connected by the action of microorganisms can be easily pulverized even at room temperature, and is desired at a very low cost of about several hundred yen per kg. It is possible to grind to a particle size of.

The material of the foamed resin according to the present invention is not particularly limited. Examples of the synthetic resin material include polyurethane foam, polystyrene foam, polyethylene foam (PEF), polypropylene foam (PPF), and phenol foam. Moreover, carbonized cork etc. can be mentioned as a natural material.
Moreover, the said microorganisms should just be microorganisms which have resolution | decomposability with respect to resin which comprises a foamed resin. For example, when the foamed resin is made of urethane, it is not particularly limited as long as it is a microorganism having urethane decomposability, but is preferably a microorganism having a sufficiently high ability to decompose urethane. As such a microorganism, for example, a microorganism belonging to the genus Streptomyces (see Patent Document 1) can be preferably used.

  As an example of a microorganism having urethane decomposability, a microorganism (Streptomyces C13a) specified by the accession number FERM P-21770 can be given. On February 12, 2009, the microorganism was deposited at the Patent Organism Depositary (National Institute of Advanced Industrial Science and Technology, Tsukuba City 1-1-1 Tsukuba Center Chuo No. 6) with the above accession number. ing. In addition, as long as it has the urethane adsorption | suction and resolution | decomposability equivalent to this, the mutant of the said microorganism can also be used preferably. Specifically, for example, S.M. albogriseolus (NBRC12834), S. alboliseolus. thermolyticus (NBRC14269), and S. Viridodiastaticus (NBRC13106) or the like can be preferably used.

(Method for producing foamed resin)
The foamed resin according to the present invention is produced by allowing a microorganism having a resolution to act on a foamed resin having independent bubbles to the resin constituting the foamed resin, and then pulverizing it to a desired size. Is possible. As described above, the foamed resin can include, for example, polyurethane foam, polystyrene foam, polyethylene foam (PEF), polypropylene foam (PPF), phenol foam, and the like as synthetic resin materials, and carbonized as a natural material. Cork etc. can be mentioned. Moreover, the said microorganisms should just be microorganisms which have resolution | decomposability with respect to the resin which comprises a foamed resin, and when the resin is polyurethane, the above-mentioned microorganisms which have urethane resolution can be utilized.

In the foamed resin having independent bubbles as a starting material, the size of the bubbles is not particularly limited, and various types can be used. For example, a foamed resin having an independent bubble particle size of about 10 μm or more and 300 μm or less can be used. Generally, the structure of a foamed resin is determined by a foaming agent added at the time of molding. The foamed resin as the starting material does not need to be completely independent of all the bubbles, and may include a portion where the bubbles are connected in part.
In the following, the resin constituting the foamed resin is polyurethane, and the foamed resin of the present invention is produced by taking as an example the case where it is a microorganism specified by the accession number FERM P-21770 as a microorganism having a resolution for the polyurethane. A method will be described.

  As the urethane foam having independent bubbles, for example, waste materials such as a bed, an automobile seat, and a steering can be used. These waste materials have high physical strength and are difficult to pulverize, but they are pulverized by processing them into a foamed resin having a structure in which at least some of the independent bubbles communicate with each other by the action of microorganisms having urethane resolution. Can be easier.

In the case of producing the foamed resin according to the present invention using the foamed urethane having independent bubbles, the step of treating the material to be treated containing the foamed urethane having independent bubbles with the unsaturated fatty acid, and the unsaturated fatty acid. It is preferable to perform a step of allowing a microorganism belonging to the genus Streptomyces having urethane resolution to act on the treated material.
A foamed resin according to the present invention can be produced by allowing a microorganism having urethane resolution to act on foamed urethane having independent bubbles, but before that, the foamed urethane is made of unsaturated fatty acid before the microorganism is allowed to act. By treating it, the decomposition action of urethane by microorganisms can be dramatically increased.

The unsaturated fatty acid may be an unsaturated fatty acid containing one or more double bonds in the structure. In addition, the unsaturated fatty acid is preferably liquid under the use temperature condition of room temperature because the material to be treated can be easily treated. In this case, room temperature means, for example, about 0 ° C. or more and 35 ° C. or less.
Examples of the unsaturated fatty acid include oleic acid, linoleic acid, palmitoleic acid, α-linolenic acid, γ-linolenic acid, arachidonic acid, docosahexaenoic acid (DHA), erucic acid, succinic acid, Linderic acid, palmitoleic acid, and elaidin. An acid etc. are mentioned. These unsaturated fatty acids may be used alone or in a combination of two or more.
The unsaturated fatty acid is preferably an unsaturated fatty acid containing one unsaturated bond rather than one containing two or more double bonds in the structure.
Among the above unsaturated fatty acids, oleic acid, erucic acid, and linoleic acid can be particularly preferably used.

  Examples of the method of treating the material to be treated with the unsaturated fatty acid include a method of immersing the material to be treated in the unsaturated fatty acid or applying an unsaturated fatty acid to the material to be treated. In particular, the method of immersing the material to be treated in the unsaturated fatty acid is preferable because the unsaturated fatty acid can act on the entire material to be treated and is a simple method.

  The longer the time for treating the material to be treated with the unsaturated fatty acid, the better. However, the effect can be obtained even for several seconds. In order to obtain a higher effect, it is preferable to perform the treatment for about 1 hour or more. In addition, in the case of performing industrially, it is disadvantageous to perform the treatment for an excessively long time, and therefore it is preferable to set it to about 48 hours at the longest. From these viewpoints, the time for treating the material to be treated with the unsaturated fatty acid is more preferably 8 hours or more and 24 hours or less.

  The temperature at the time of processing a to-be-processed material with an unsaturated fatty acid is not specifically limited, It is preferable to carry out in the temperature range in which an unsaturated fatty acid hold | maintains a liquid. For example, when oleic acid or linoleic acid is used as the unsaturated fatty acid, the treatment may be performed at about 30 ° C.

In the step of treating the material to be treated with the unsaturated fatty acid, the unsaturated fatty acid and alcohol are preferably mixed and used. In general, unsaturated fatty acids have a high viscosity and are difficult to handle. However, when mixed with alcohol, the viscosity decreases and the handling is improved. Moreover, when the viscosity of the treatment liquid in which the unsaturated fatty acid and the alcohol are mixed is lowered, it is possible to suppress the phenomenon that the materials to be treated immersed in the treatment liquid are aggregated and fixed. As a result, stable processing with little variation is possible. Furthermore, since the treatment liquid having a low viscosity penetrates quickly into the material to be treated, not only the surface of the material to be treated but also the entire treatment can be performed.
Thus, by making the said processing liquid which mixed the unsaturated fatty acid and alcohol acted on a to-be-processed material, physical properties, such as a breaking stress and elongation of a to-be-processed material, can be reduced significantly. In the case where microorganisms are allowed to act on the material to be treated, the material to be treated is crushed as small as possible, rather than a large lump, so that the decomposition efficiency of the microorganisms is improved. For this reason, when the physical properties such as the breaking stress and elongation of the material to be treated are reduced as described above, it is preferable that the material to be treated is easily crushed.

  Further, by allowing microorganisms to act on the material to be treated that has been sufficiently treated with the unsaturated fatty acid not only on the surface but also on the inside, it is possible to proceed the decomposition uniformly to the inside of the material to be treated. If the decomposition is sufficiently advanced to the inside of the material to be treated, it becomes easy to finely pulverize the material to be treated after the microorganisms act on it.

  Moreover, the effect which wash | cleans the surface of a to-be-processed material is also acquired by using the processing liquid which mixed unsaturated fatty acid and alcohol. Silicone release agents and acrylic urethane-based barrier coats may adhere to the surface of the treated material containing urethane foam, and these deposits reduce the decomposition efficiency of the treated material by microorganisms. Is. In the case of such a material to be treated, by using a treatment liquid in which the unsaturated fatty acid and the alcohol are mixed, the silicone-based release agent and the acrylic urethane-based barrier coat adhered to the surface of the material to be treated are removed. It is possible to prevent degradation of the decomposition efficiency of the material to be treated by microorganisms.

  The type of the alcohol is not particularly limited, but preferably has a lower viscosity than the unsaturated fatty acid and has sufficient solubility affinity for the unsaturated fatty acid. Moreover, the thing with the high cleaning effect of the said silicone type mold release agent or an acryl urethane type barrier coat is preferable. From the standpoint of availability, it is preferable to use a lower alcohol. Specifically, any one selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-butanol and 2-methyl-2-butanol Alternatively, a mixture of two or more kinds can be preferably used.

  The mixing ratio of the unsaturated fatty acid and the alcohol is preferably 1: 9 to 7: 3 in terms of volume ratio in consideration of reducing the amount of the unsaturated fatty acid adsorbed as much as possible in consideration of the subsequent steps. : 7 to 6: 4 is more preferable, and 5: 5 is even more preferable.

  When the alcohol is used for the purpose of cleaning the surface of the material to be treated, the material to be treated may be washed with alcohol before the material to be treated is treated with the unsaturated fatty acid. In this case, the material to be treated may be washed by immersing the material in alcohol and shaken, and then the unsaturated fatty acid or a mixture of the unsaturated fatty acid and alcohol may be allowed to act on the material to be treated.

The method for causing the microorganism to act on the material to be treated is not particularly limited as long as the material to be treated and the microorganism are in contact with each other. For example, there is a method in which a material to be treated is added to a culture solution in which the microorganism is cultured and culture of the microorganism is continued. In addition, a to-be-processed material may be added to the culture solution which does not contain microorganisms, and the said microorganisms may be newly inoculated here.
Since the microorganism belonging to the genus Streptomyces is a soil fungus, it has a strong growth potential at a relatively low temperature, a simple medium of carbon and inorganic salts, and is cultured by a simple method (general shaking culture). it can. In addition, it can survive in harsh environments due to the formation of spores, and generally produces antibacterial compounds, and thus has the advantage of high inhabitability even in a heterogeneous microbial environment. The medium and culture method for culturing the microorganism may be performed according to the description in Patent Document 1.

The longer the time for which the microorganisms are allowed to act on the material to be treated, the better. However, the urethane may be sufficiently decomposed in consideration of the content of urethane in the material to be treated and the amount of microorganisms to act.
The temperature at which the microorganisms are allowed to act on the material to be treated may be a temperature suitable for the growth of microorganisms or the decomposition of urethane, for example, 26 to 45 ° C, preferably around 30 to 45 ° C.

It is also possible to cause the microorganism to act while treating the material to be treated with the unsaturated fatty acid, that is, to cause the microorganism to act on the material to be treated in the presence of the unsaturated fatty acid. For example, the microorganism may be cultured by adding an unsaturated fatty acid and a material to be treated to the microorganism culture solution. The concentration of the unsaturated fatty acid at this time may be 0.1% (W / V) or less.
By doing in this way, it becomes possible to decompose | disassemble the urethane contained in a to-be-processed material by a simpler method.

[Resin molding]
The resin molded body according to the present invention is characterized by molding the foamed resin according to the present invention.
The resin molded body can be manufactured using, for example, a known chip urethane manufacturing facility. That is, a binder as an adhesive component and the foamed resin according to the present invention may be blended and heated and press-molded while passing steam. As a result, a resin molded body having an elastic structure in which the foamed resin is solidified in a desired shape can be obtained while the fine cavities formed on the wall surfaces of the bubbles are maintained without being blocked. As the binder, for example, a moisture curable isocyanate prepolymer can be preferably used.
FIG. 5A shows an appearance photograph of a resin molded body obtained by molding a foamed resin having an average particle diameter of 5000 μm. Moreover, the external appearance photograph of the resin molding which shape | molded the foaming resin whose average particle diameter is 300 micrometers in FIG.5 (B) is shown.

  The shape of the resin molded body is not particularly limited, and may be appropriately changed according to the purpose. In addition, chip urethane is known as a reproduction of the conventional pulverized foam resin, but because of the large pulverized urethane pulverized material, complicated shapes cannot be molded, and its use has been limited. . On the other hand, the resin molded body according to the present invention can be processed into a complicated shape by using a powdery foamed resin of 50 μm or more and 1000 μm or less as the foamed resin of the raw material.

When the average particle diameter of the foamed resin as the material of the resin molded body is 2000 μm or more and 8000 μm or less, a resin molded body that can be preferably used as a sound-absorbing material or a water-absorbing material can be produced, particularly in a low frequency region. It becomes a resin molding excellent in sound absorption.
Even when the average particle diameter of the foamed resin used as the material of the resin molded body is 50 μm or more and 1000 μm or less, it is possible to produce a resin molded body that can be preferably used as a sound absorbing material or a water absorbing material, and is particularly excellent in water retention. A resin molded body is obtained.
In addition, when manufacturing the resin molding which concerns on this invention, it mixes and manufactures foam resin with an average particle diameter of 2000 micrometers or more and 8000 micrometers or less, and an average particle diameter of 50 micrometers or more and 1000 micrometers or less. Also good.

[Laminated resin molded product]
The laminated resin molded product according to the present invention is characterized by having at least one resin molded product obtained by molding the foamed resin according to the present invention into a layer.
For example, as described above, the laminated resin molded body is manufactured by using a known chip urethane manufacturing facility by using the foamed resin of the present invention as a material, and producing another layered resin molded body having at least one layer. What is necessary is just to laminate | stack with a layered resin molding. For example, by laminating a resin molded body manufactured using a foamed resin having an average particle diameter of 2000 μm or more and 8000 μm or less and a resin molded body manufactured using a foamed resin having an average particle diameter of 50 μm or more and 1000 μm or less. A laminated resin molded product having the characteristics of both resin molded products is obtained.

[Sound absorbing material]
The sound absorbing material according to the present invention is characterized by using the foamed resin, the resin molded body, or the laminated resin molded body according to the present invention.
In general, the sound absorbing effect of the sound absorbing material is exhibited by absorbing sound vibration energy and converting it into thermal energy. In the sound absorbing material using the foamed resin, the foamed resin itself is elastic and easily absorbs energy, and the foamed resin itself macroscopically vibrates due to being miniaturized. Due to the synergistic effect of these two phenomena, it is considered that an excellent sound absorbing effect is exhibited particularly in a high frequency region of 2000 Hz or higher. In particular, a sound absorbing material using a foamed resin having an average particle diameter of 50 μm or more and 1000 μm or less shows a sound absorption coefficient equivalent to a sinsalate (sound absorbing heat insulating material manufactured by 3M), which has a proven record as a sound absorbing material, in a high frequency region.
The sound absorbing material using the resin molded body or the laminated resin molded body has an excellent sound absorbing effect particularly in a low frequency region of 1000 Hz or less. It is considered that this is because the entire surface is shaken by receiving low-frequency sound waves having a long wavelength on the continuous surface of the resin molded body or the laminated resin molded body, thereby producing a sound absorbing effect. In the low frequency region, a resin molded body produced using a foamed resin having an average particle diameter of 2000 μm or more and 8000 μm or less has a particularly high sound absorption coefficient.
The sound absorbing material according to the present invention can be preferably used as a sound absorbing heat insulating material for a refrigerator, a vending machine, or the like.

[Water absorbing material]
The water-absorbing material according to the present invention uses the foamed resin, resin molded body or laminated resin molded body according to the present invention.
As described above, the foamed resin according to the present invention has a structure in which bubbles are connected by a fine cavity. For this reason, the water-absorbing material using the foamed resin has a high water-absorbing property, and further, the water once absorbed is difficult to be released and has excellent water retention properties. This is presumably because the water absorbed by the surface tension of water is retained as it is while the water is absorbed by the bubble portions connected by capillary action. In particular, foamed resin having an average particle size of 50 μm or more and 1000 μm or less converges to a small size with a fine cavity diameter of about 1 to 2 μm, so that moisture absorbed by capillary action is dissipated by the surface tension of water. It is hard to be done.
Moreover, the water absorbing material using the said resin molded object or laminated resin molded object has the outstanding water absorption and water retention similarly.
The water-absorbing material according to the present invention can be used, for example, as a planter for plant growth or a humidity control material. From the effect of excellent water retention, it can be preferably used for plant growth, and can also be applied to the greening of rooftops of buildings.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

[Example 1]
(Material to be treated)
A material obtained by pulverizing waste urethane foam used for automobile steering to a size of about 5 mm square was used as a material to be treated.
For the pulverization of the foamed urethane waste, a cutting mill SM300 manufactured by Vander Scientific Co., Ltd. (formerly Lecce Co., Ltd.) was used.
(Unsaturated fatty acid)
As the unsaturated fatty acid, oleic acid (manufactured by Wako Pure Chemical Industries, Ltd., grade: Wako first grade) was used.
(Microorganism)
A microorganism (strain: C13a) specified by the accession number FERM P-21770 was used as a microorganism having urethane adsorption / degradability.

(Culture medium)
As a medium for culturing the microorganism, YES-G medium prepared as follows was used.
A KH ₂ PO ₄ solution and a Na ₂ HPO ₄ solution having concentrations shown in Table 1 below were prepared, and 10 mL and 40 mL were mixed to prepare Solution A. Other Solution B, Solution C, and Solution D were solutions having compositions as shown in Table 1 below. The prepared Solutions A to D were sterilized under the conditions of 121 ° C. and 20 minutes.
A 3 L Erlenmeyer flask was mixed with 20 mL of Solution A, 4.0 g of gelatin, 970 mL of distilled water, and 0.5 g of (NH ₄ ) ₂ SO ₄ , and sterilized at 121 ° C. for 20 minutes. After cooling, 10 mL of Solution B, 0.1 mL of Solution C (10-fold concentration), and 2 mL of Solution D were added to the 3 L Erlenmeyer flask to prepare a YES-G medium.

-Process of treating material to be treated with unsaturated fatty acid-
A solution prepared by diluting oleic acid with 99% ethanol to a concentration of 10% (W / W) was prepared and added to a 100 mL Erlenmeyer flask.
About 4 to 5 g of the material to be treated was placed in the 100 mL Erlenmeyer flask, the material to be treated was completely immersed, covered with aluminum foil, and treated at room temperature for 1 hour.
After the treatment time had elapsed, the inside of the Erlenmeyer flask was washed with tap water and distilled water, and further distilled water was added and washed with ultrasonic waves. The material to be treated was taken out from the Erlenmeyer flask and further washed with distilled water. Thereafter, it was dried overnight at 40 ° C. and sterilized under the conditions of 121 ° C. and 20 minutes.

-Process of causing microorganisms to act on treated material-
The microorganism (C13a) was inoculated into 100 mL of YES-G medium and cultured with shaking to obtain a preculture solution. The culture conditions were 40 ° C., 140 rpm, and 11 days.
10 mL of the preculture solution thus obtained was added to 1 L of YES-G medium and shake-cultured to obtain a main culture solution. The culture conditions were 40 ° C., 140 rpm, and 9 days.
50 mL of the main culture solution was added to the 100 mL Erlenmeyer flask containing the material to be processed prepared above and shake-cultured. The culture conditions were 40 ° C. and 80 rpm.
The period during which microorganisms are allowed to act was one week.

-Washing process-
After each culture period, the bacterial solution was discarded, and the material to be treated was rinsed with distilled water and then ultrasonically washed with 99% ethanol. Further, the material to be treated was washed with distilled water and then dried at 40 ° C. overnight.
As a result, a particulate foamed resin (hereinafter referred to as “particle product”) having a structure in which at least some of the independent bubbles are connected by the action of microorganisms and having an average particle diameter of 5000 μm was obtained. The particle product was reduced by 3 mass% with respect to the weight before processing.
The average particle size of the foamed resin was measured using a laser analysis scattering type particle size distribution measuring apparatus LA960 (manufactured by Horiba, Ltd.). Sampling was performed by wet measurement using distilled water as a medium.

[Example 2]
The particle product obtained in Example 1 was pulverized by using an ultracentrifugal pulverizer (Rotor Mill ZM200) manufactured by Vander Scientific Co., Ltd. (formerly Lecce Co., Ltd.).
Unlike conventional urethane foam having independent bubbles, it could be easily pulverized even at room temperature, and a powdered foamed resin (hereinafter referred to as “powder product”) having an average particle size of 300 μm could be obtained.

[Example 3]
The particle product obtained in Example 1 was mixed with a binder as an adhesive component. As the binder, a moisture curable isocyanate prepolymer (manufactured by Token Resin Co., Ltd.) was used. Then, a disk-shaped resin molded body (hereinafter referred to as “particle molded product”) having a diameter of 90 cm and a thickness of 20 mm as shown in FIG. 5 was manufactured by press molding while passing steam.
A steam press was used for press molding.

[Example 4]
Resin molded body as shown in FIG. 6 (hereinafter referred to as “powder molded product”) in the same manner as in Example 3 except that the particle product used in Example 3 was changed to the powder product obtained in Example 2. Manufactured.

-Evaluation-
<Microscope observation>
The state of the cell of the particle product obtained in Example 1 was observed with a microscope. The result is shown in FIG. As shown in FIG. 1B, fine cavities having a diameter of about 1 μm to 10 μm were observed on the wall surfaces of the independent bubbles. In addition, it was observed that this fine cavity penetrated into the cell.
Similarly, the state of the cell of the powder product obtained in Example 2 was observed with a microscope. The result is shown in FIG. As shown in FIG. 4, the fine cavities on the wall surfaces of the independent bubbles of the powder product were uniformed to have a diameter of about 1 μm. This is because, in the process of manufacturing the powder product, the particle product was broken starting from a fine cavity portion having a relatively large diameter.

<Sound absorption characteristics>
(Foamed resin)
The sound absorption characteristics of the particle product obtained in Example 1 and the powder product obtained in Example 2 were evaluated. The sound absorption characteristics were evaluated according to ISO 10534-2 and ASTM E 1050 using a normal incidence sound absorption measurement system (DS2000) manufactured by Ono Sokki Co., Ltd.
Specifically, a system that calculates normal incidence sound absorption coefficient, reflection coefficient, and standardized impedance by radiating sound waves from the speaker built into the acoustic impedance tube end into the tube and measuring the transfer function between two microphones in the tube It is. The specifications of the acoustic impedance tube were changed in the high frequency region and the low frequency region. The B tube in the high frequency region has a length of 500 mm and an inner diameter of 29φ, and the A tube in the low frequency region has a length of 835 mm and an inner diameter of 100φ.
FIG. 7 shows the measurement result in the high frequency region, and FIG. 8 shows the measurement result in the low frequency region.

In FIG. 7 and FIG. 8, “initially pulverized product” means a product obtained by pulverizing urethane foam having independent bubbles, which has not been pretreated with fatty acids or treated with microorganisms, to a size of about 5 mm square. “Synthrate” means a sound absorbing heat insulating material manufactured by 3M.
As shown in FIG. 7, a large sound absorption effect was recognized particularly in a high frequency region of 2000 Hz or higher. In both the particle product and the powder product, the sound absorption characteristics were improved compared to the initial pulverized product. In the case of a powder product, an effect close to that of a synthesizer with a proven track record as a sound absorbing material was obtained.

Generally, a material having high conversion efficiency that absorbs vibration energy of sound and converts it into heat energy is suitable as the sound absorbing material. In the case of powder products, the foamed resin itself is an elastic body that absorbs energy easily, and the microfabrication of the foamed resin itself as a result of miniaturization has improved the sound absorption rate due to the synergistic effect of these two phenomena. Conceivable.
On the other hand, as shown in FIG. 8, a very large sound absorption effect was not obtained in the low frequency region. In the low frequency region, the sound wavelength becomes longer, the effect of macro vibration is reduced, and because the elastic surface is not continuous, it is considered that a long wavelength energy absorption loss occurred.

(Resin molding)
The sound absorption characteristics in the low frequency region of the particle molded product obtained in Example 3 and the powder molded product obtained in Example 4 were evaluated in the same manner as the above foamed resin. The result is shown in FIG.
As shown in FIG. 9, in the case of the resin molded body, an improvement in the sound absorption characteristics in the low frequency region, which was difficult with the particle product and the powder product, was recognized. This is considered to be due to the fact that the entire surface of the resin molded body is shaken by receiving low-frequency sound waves having a long wavelength on the continuous surface of the resin molded body. In addition, since the surface of the particle molded product is uneven, it is considered that the sound absorption characteristics are further improved by this surface shape.

<Water absorption test>
The particle molded product obtained in Example 3 and the powder molded product obtained in Example 4 were evaluated for water absorption and water retention as follows.
(Water absorption test)
Three test pieces each having a thickness of about 25 mm, a width of about 25 mm, and a length of about 25 mm were cut out from the particle molded product and the powder molded product, and the dimensions were measured in units of 0.1 mm. After drying the test piece at 60 ° C. for 24 hours, immerse the test piece in a container containing pure water at room temperature so that it is completely buried 30 mm below the surface of the water, and slowly stir the water once every few hours. For 24 hours. After 24 hours, the test piece was taken out, placed on a sieve inclined at about 45 ° from the vertical and allowed to stand for 30 seconds, and then each mass was measured in units of 0.01 g. This was taken as the amount of water absorption, converted to a surface area of 100 cm ² , and an average of three points was obtained and evaluated.
The results of the water absorption test are shown in FIG. In FIG. 10, “sponge” means a so-called sponge of foamed resin having continuous pores, and “free foamed product” means foamed urethane having independent bubbles.

(Water retention test)
A metal mesh was placed on the absorbent cotton so that the test piece and the absorbent cotton were not in direct contact with each other, and the water-absorbed test piece used in the water absorption test was placed thereon, and the weight was measured over time. In addition, the test piece which showed the water absorption amount closest to the average value of the water absorption amount in the water absorption test was used as a test piece for the water retention test. At the time of measurement, the upper and lower sides of the test piece were determined, and the measurement was always performed with the same side down.
The results of the water retention test are shown in FIG. In FIG. 11, “sponge” and “free foamed product” mean the same as in FIG. 10.

  As shown in FIGS. 10 and 11, it was confirmed that both the particle molded product and the powder molded product are excellent in water absorption and water retention. In particular, the powder molded product showed higher water absorption and higher water retention than the particle molded product. This is because the powdered foamed resin has a uniform microcavity with a small diameter of about 1 to 2 μm, so that the moisture absorbed by the capillary phenomenon is more than the particle molded product due to the surface tension of the water. This is thought to be due to the fact that it was difficult to be released.

Claims (8)

  A foamed resin characterized by having a structure in which at least some of the independent bubbles are linked by the action of microorganisms and having an average particle size of 2000 μm or more and 8000 μm or less.   A foamed resin characterized by having a structure in which at least some of the independent bubbles are linked by the action of microorganisms, and having an average particle size of 50 μm or more and 1000 μm or less.   The foamed resin according to claim 1 or 2, wherein the foamed resin is urethane.   The foamed resin according to any one of claims 1 to 3, wherein the microorganism is a microorganism belonging to the genus Streptomyces having urethane decomposability.   A resin molded product obtained by molding the foamed resin according to claim 1 and / or 2.   A laminated resin molded article comprising at least one foamed resin molded article obtained by molding the foamed resin according to claim 1 and / or claim 2 into a layer.   A sound-absorbing material using the foamed resin according to any one of claims 1 to 4, the resin molded product according to claim 5, or the laminated resin molded product according to claim 6.   A water-absorbing material using the foamed resin according to any one of claims 1 to 4, the resin molded product according to claim 5, or the laminated resin molded product according to claim 6.