JP6799241B2 - Foam resin manufacturing method - Google Patents

Description

The present invention relates to a method for producing a foamed resin, and more particularly to a method for producing a foamed resin for a sound absorbing material or a water absorbing material that has been decomposed using a microorganism.

Polyurethane is a polymer having a urethane bond and is also called a urethane resin. Polyurethane is gradually decomposed by hydrolysis by water and the influence of nitrogen oxides (NOx) in the air, salt, ultraviolet rays, heat, microorganisms, etc., and produces compounds harmful to the human body and aquatic organisms. Since the leaked polyurethane may cause enormous environmental pollution, it is usually collected by taking preventive measures such as adsorbing it on earth and sand, enclosing it, and sealing it in a container after treatment. Recycling systems have also been developed for polyurethane, but about 40% of waste polyurethane is still landfilled.

The inventors have found a novel microorganism having an adsorptive ability and resolution for urethane in soil and filed a patent application (Patent Document 1). From the mycological properties and DNA analysis, the microorganism was identified as a novel actinomycete belonging to the genus Streptomyces. Since this microorganism has an adsorptive property to urethane, urethane particles dispersed in water can be bound and aggregated to effectively remove (adsorb and purify) urethane.

JP-A-2010-220610

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

By the way, as urethane, a material having an elastic body and high viscoelasticity such as flexible polyurethane is also known, but it is 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 pulverizing such urethane foam, a method of freezing and solidifying with liquid nitrogen and then pulverizing is known. However, such a method is not practical because the equipment becomes large and the running cost becomes high.

Therefore, the present invention provides a processing method for facilitating pulverization of a foamed resin such as urethane foam having independent bubbles, and provides a method for producing a foamed resin having novel characteristics obtained by the processing method. With the goal.

As a result of repeated earnest investigations by the present inventors in order to solve the above problems, at least some of the bubbles are connected to each other by allowing microorganisms to act on the foamed resin having independent bubbles, and the particle size is further adjusted to a predetermined size. We found that this is effective, and completed the present invention.

That is, the present invention adopts the following configuration.
(1) A method for producing a foamed resin for a sound absorbing material or a water absorbing material, which has a structure in which at least a part of independent bubbles are connected by the action of microorganisms and has an average particle size of 2000 μm or more and 8000 μm or less. There,
The foamed resin is urethane foam,
The process of treating urethane foam with independent bubbles with unsaturated fatty acids,
A step of allowing a microorganism belonging to the genus Streptomyces having urethane resolution to act on the urethane foam treated with the unsaturated fatty acid to form a structure in which at least a part of independent bubbles of the urethane foam are connected. When,
A step of pulverizing urethane foam after allowing the microorganisms to act so that the average particle size is 2000 μm or more and 8000 μm or less.
Have,
Microcavities of 1 μm or more and 10 μm or less are formed on the wall surface of the cells in the portion where the independent cells are connected to each other.
A method for producing a foamed resin for a sound absorbing material or a water absorbing material.
(2) A method for producing a foamed resin for a sound absorbing material or a water absorbing material, which has a structure in which at least a part of independent bubbles are connected by the action of microorganisms and has an average particle size of 50 μm or more and 1000 μm or less. There,
The foamed resin is urethane foam,
The process of treating urethane foam with independent bubbles with unsaturated fatty acids,
A step of allowing a microorganism belonging to the genus Streptomyces having urethane resolution to act on the urethane foam treated with the unsaturated fatty acid to form a structure in which at least a part of independent bubbles of the urethane foam are connected. When,
A step of pulverizing urethane foam after allowing the microorganisms to act so that the average particle size is 50 μm or more and 1000 μm or less.
Have,
Microcavities of 1 μm or more and 10 μm or less are formed on the wall surface of the cells in the portion where the independent cells are connected to each other.
A method for producing a foamed resin for a sound absorbing material or a water absorbing material.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a method for producing a foamed resin having characteristics as a new material having both characteristics of a foamed resin having independent bubbles and a foamed resin having communicated bubbles. The foamed resin obtained by the method has a predetermined particle size, so that it can exhibit excellent properties of water absorption and sound absorption.

(A) It is a micrograph which observed the state of the foam cell before letting a microorganism act on urethane foam. (B) It is a micrograph which observed the state of the foam cell after letting a microorganism act on urethane foam. It is a photograph which shows the appearance of the foamed resin which has an average particle diameter of 2000 μm or more and 8000 μm or less. It is a photograph showing the appearance of the foamed resin having an average particle diameter of 50 μm or more and 1000 μm or less. It is a micrograph which observed the surface of the foamed resin with an average particle diameter of 300 μm. It is a photograph which shows an example of the appearance of the resin molded body which molded the foamed resin with an average particle diameter of 5000 μm. It is a photograph which shows an example of the appearance of the resin molded body which molded the foamed resin with an average particle diameter of 300 μm. It is a graph which shows the result of the sound absorption coefficient in a high frequency region of the foamed resin measured in an Example. It is a graph which shows the result of the sound absorption coefficient in a low frequency region of the foamed resin measured in an Example. It is a graph which shows the result of the sound absorption coefficient of the resin molded article measured in an Example. It is a graph which shows the result of the water absorption rate of the resin molded article measured in an Example. It is a graph which shows the result of the water retention of the resin molded article measured in an Example.

[Foam resin]
The foamed resin according to the present invention has a structure in which at least a part of 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 communicated bubbles can be obtained.

For example, when the average particle size of the foamed resin having a structure in which at least a part of independent bubbles are connected 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 product formed by using the foamed resin having an average particle size 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 product having excellent sound absorption in the low frequency region, the average particle size of the foamed resin is more preferably 4000 μm or more and 5000 μm or less.
In the present invention, the average particle size of the foamed resin means the median diameter of the volume average particle size.

Further, the foamed resin having a structure in which at least a part of 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. .. Foamed resins having an average particle size of 50 μm or more and 1000 μm or less exhibit excellent properties in terms of sound absorption coefficient, water absorption, and water retention in a high frequency region, as compared with those having an average particle size of 2000 μm or more and 8000 μm or less. To do. In addition, a resin molded product molded using a foamed resin having an average particle size of 50 μm or more and 1000 μm or less is also excellent in sound absorption coefficient in a low frequency region. In order to produce a foamed resin molded product having excellent water retention, the average particle size 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 allowing a microorganism having a resolution to act on the foamed resin having independent bubbles and then pulverizing the foamed resin so as to have a predetermined particle size. .. FIG. 1 shows a microscopic photograph of a cross section of a foamed resin having independent bubbles before and after the action of microorganisms. FIG. 1 (A) shows the state before the action of the microorganism, and FIG. 1 (B) shows the state after the action of the microorganism.
When a microorganism having a 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 surface of the bubbles. As the decomposition action by microorganisms progresses, independent bubbles come to be connected by microcavities. As a result, the foamed resin after the action of the microorganisms exhibits the characteristics of both the foamed resin having independent bubbles and the foamed resin having communicated bubbles.

The foamed resin having a structure in which at least a part of the independent bubbles are connected by the action of microorganisms can be easily pulverized to a desired particle size because many starting points of fracture appear when pulverized. FIG. 2 shows a photograph of a particulate foam resin having an average particle size of 2000 μm or more and 8000 μm or less. Further, 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 the microorganism is not particularly limited, and it may be appropriately selected depending on the intended 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. When the average particle size of the foamed resin is 50 μm or more and 1000 μm or less, it may be crushed by, for example, a method using a centrifugal type crusher.

As shown in FIG. 1 (B), when a microorganism is allowed to act on a foamed resin having independent bubbles, the diameter of the microcavities formed on the wall surface of the bubbles is about 1 to 10 μm, and the size of the diameter is constant. Not done. However, when 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 substance having a size of about 1 μm. This is because when the foamed resin is crushed, it breaks starting from a portion of a fine cavity having a relatively large diameter. As a result, in the foamed resin having a particle size of 50 μm or more and 1000 μm or less, the diameter of the fine cavities is constant, and the material properties are more stable. FIG. 4 shows a micrograph of the surface of a foamed resin having an average particle size of 300 μm.

It is very difficult to crush a conventional foamed resin having independent bubbles. For example, when the foamed resin is frozen and solidified and crushed, it costs nearly 100,000 yen per kg, which is not realistic. On the other hand, a foamed resin having a structure in which at least a part of 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 the particle size of.

The material of the foamed resin according to the present invention is not particularly limited, and examples of the synthetic resin material include polyurethane foam, polystyrene foam, polyethylene foam (PEF), polypropylene foam (PPF), and phenol foam. As a natural material, carbonized cork and the like can be mentioned.
Further, the microorganism may be any microorganism having a resolution with respect to the resin constituting the 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 resolution, but it 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 decomposing ability, a microorganism (Streptomyces C13a) specified by accession number FERM P-21770 can be mentioned. The microorganism was deposited at the National Institute of Advanced Industrial Science and Technology Patent Organism Depositary Center (1-1-1 Higashi, Tsukuba City, Ibaraki Prefecture, Tsukuba Center Central No. 6) on February 12, 2009 with the above-mentioned deposit number. ing. The mutant strain of the above microorganism can also be preferably used as long as it has the same urethane adsorption and resolution. Specifically, for example, S. albogriseolus (NBRC12834), S.A. thermoluteus (NBRC14269), and S.M. Viridodistaticus (NBRC13106) and the like can be preferably used.

(Manufacturing method of foamed resin)
The foamed resin according to the present invention is produced by allowing a microorganism having a resolution on the resin constituting the foamed resin to act on the foamed resin having independent bubbles, and then pulverizing the foamed resin to a desired size. Is possible. As described above, as the foamed resin, for example, polyurethane foam, polystyrene foam, polyethylene foam (PEF), polypropylene foam (PPF), phenol foam and the like can be mentioned as synthetic resin materials, and carbonized as a natural material. Cork can be mentioned. Further, the microorganism may be any microorganism having a resolution with respect to the resin constituting the foamed resin, and when the resin is polyurethane, the above-mentioned microorganism having a urethane resolution can be used.

In the foamed resin having independent bubbles as a starting material, the size of the bubbles is not particularly limited, and various ones can be used. For example, a foamed resin having a particle size of independent bubbles of 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 used as a starting material does not have to be completely independent of all the bubbles, and may include a portion in which the bubbles are connected to each other.
In the following, the foamed resin of the present invention will be produced by taking as an example the case where the resin constituting the foamed resin is polyurethane and the microorganism specified by the accession number FERM P-21770 as a microorganism having a resolution for the polyurethane. The method will be described.

As the urethane foam having independent bubbles, for example, waste materials such as beds, automobile seats, and steering wheels can be used. These waste materials have high physical strength and are difficult to crush, but they are crushed by allowing microorganisms having urethane resolution to act on them to process them into a foamed resin having a structure in which at least a part of independent bubbles are communicated. Can be made easier.

When the foamed resin according to the present invention is produced using urethane foam having independent bubbles, a step of treating a material to be treated containing urethane foam having independent bubbles with an unsaturated fatty acid and the unsaturated fatty acid It is preferable to carry out a step of allowing a microorganism belonging to the genus Streptomyces having urethane decomposability to act on the material to be treated in 1.
The foamed resin according to the present invention can be produced by allowing a microorganism having urethane resolution to act on urethane foam having independent bubbles. At that time, urethane foam is made of unsaturated fatty acids before the microorganism is allowed to act. By treating it, the decomposition action of urethane by microorganisms can be dramatically enhanced.

The unsaturated fatty acid may be an unsaturated fatty acid containing one or more double bonds in its structure. Further, it is preferable that the unsaturated fatty acid is liquid under the operating temperature condition of room temperature because the material to be treated can be easily treated. In this case, the room temperature means, for example, about 0 ° C. or higher and 35 ° C. or lower.
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, touhacic acid, linderic acid, palmitoleic acid, and elaidic acid. Examples include acid. These unsaturated fatty acids may be used alone or in combination of two or more.
Further, as the unsaturated fatty acid, an unsaturated fatty acid containing one double bond is preferable to 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 and a method of applying the 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 it is a simple method.

The longer the time for treating the material to be treated with the unsaturated fatty acid is, the more preferable it is, but the effect can be obtained even in a few seconds. In order to obtain a higher effect, it is preferable to treat for about 1 hour or more. In addition, when it is carried out industrially, it is disadvantageous to carry out the treatment for too long, so it is preferable to set it to about 48 hours at the longest. From these viewpoints, it is more preferable that the time for treating the material to be treated with the unsaturated fatty acid is 8 hours or more and 24 hours or less.

The temperature at which the material to be treated is treated with the unsaturated fatty acid is not particularly limited, and it is preferable to carry out the treatment within the temperature range in which the unsaturated fatty acid holds the 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, it is preferable to use the unsaturated fatty acid mixed with alcohol. In general, unsaturated fatty acids have a high viscosity and are difficult to handle, but when mixed with alcohol, the viscosity decreases and the handleability is improved. Further, when the viscosity of the treatment liquid in which the unsaturated fatty acid and the alcohol are mixed is lowered, the phenomenon that the materials to be treated immersed in the treatment liquid aggregate and stick to each other can be suppressed. This enables stable processing with little variation. Further, since the treatment liquid having a low viscosity permeates into the inside of the material to be treated quickly, it is possible to treat not only the surface of the material to be treated but also the whole.
By allowing the treatment liquid, which is a mixture of unsaturated fatty acids and alcohol, to act on the material to be treated in this way, physical properties such as breaking stress and elongation of the material to be treated can be significantly reduced. When microorganisms are allowed to act on the material to be treated, the decomposition efficiency of the microorganisms is better when the material to be treated is crushed as small as possible than when it is a large mass. Therefore, when the physical properties such as breaking stress and elongation of the material to be treated are lowered as described above, the material to be treated is preferably small and easily crushed.

Further, by allowing microorganisms to act on the material to be treated which has been sufficiently treated with unsaturated fatty acids not only on the surface but also on the inside, decomposition can be uniformly promoted to the inside of the material to be treated. If the decomposition has progressed sufficiently to the inside of the material to be treated, it becomes easy to finely crush the material to be treated after the action of microorganisms into a powder.

Further, by using a treatment liquid in which an unsaturated fatty acid and an alcohol are mixed, the effect of cleaning the surface of the material to be treated can be obtained. Silicone-based mold release agents and acrylic urethane-based barrier coats may adhere to the surface of the material to be treated containing urethane foam, and these deposits reduce the decomposition efficiency of the material to be treated by microorganisms. It is a thing. In the case of such a material to be treated, a silicone-based release agent and an acrylic urethane-based barrier coat adhering to the surface of the material to be treated are removed by using a treatment liquid in which the unsaturated fatty acid and alcohol are mixed. It is possible to prevent the decomposition efficiency of the material to be treated by microorganisms from being lowered.

The type of the alcohol is not particularly limited, but it is preferably one having a viscosity lower than that of the unsaturated fatty acid and having a sufficient dissolving affinity for the unsaturated fatty acid. Further, those having a high cleaning effect on the silicone-based mold release agent and the acrylic urethane-based barrier coat are preferable. It is preferable to use a lower alcohol from the viewpoint of easy availability. 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 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 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 immersed in alcohol for washing such as shaking, and then the unsaturated fatty acid or a mixture thereof and alcohol may be allowed to act on the material to be treated.

The method of allowing the microorganism to act on the material to be treated is not particularly limited as long as the material to be treated is in contact with the microorganism. For example, a method of adding a material to be treated to a culture solution in which the microorganism is cultured to continue culturing the microorganism can be mentioned. The material to be treated may be added to the culture solution containing no microorganism, and the microorganism may be newly inoculated therein.
Since the microorganism belonging to the genus Streptomyces is a soil bacterium, it has a relatively low temperature, strong growth potential in 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, so it has the advantage of having a high habitat rate even in a heterogeneous microbial environment. The medium and the culturing method for culturing the microorganism may be carried out in accordance with the description in Patent Document 1.

The longer the time for the microorganisms to act on the material to be treated is preferable, but 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 on.
The temperature at which the microorganisms act on the material to be treated may be a temperature suitable for the growth of microorganisms and decomposition of urethane, for example, about 26 to 45 ° C., preferably around 30 to 45 ° C.

It is also possible to allow the microorganism to act while treating the material to be treated with the unsaturated fatty acid, that is, to allow the microorganism to act on the material to be treated in the presence of the unsaturated fatty acid. For example, the unsaturated fatty acid and the material to be treated may be added to the culture solution of the microorganism to culture the microorganism. The concentration of unsaturated fatty acid at this time may be 0.1% (W / V) or less.
By doing so, urethane contained in the material to be treated can be decomposed by a simpler method.

[Resin molded product]
The resin molded product according to the present invention is characterized in that the foamed resin according to the present invention is molded.
The resin molded body can be manufactured by using, for example, a known chip urethane manufacturing facility or the like. That is, the binder as an adhesive component and the foamed resin according to the present invention may be blended and heat-press molded while passing steam. As a result, a resin molded product having an elastic structure in which the foamed resin is solidified in a desired shape can be obtained while maintaining the fine cavities formed on the wall surface of the bubbles without being closed. As the binder, for example, a water-curable isocyanate prepolymer or the like can be preferably used.
FIG. 5A shows an external photograph of a resin molded product obtained by molding a foamed resin having an average particle size of 5000 μm. Further, FIG. 5B shows an external photograph of a resin molded body obtained by molding a foamed resin having an average particle size of 300 μm.

The shape of the resin molded product is not particularly limited, and may be appropriately changed depending on the intended purpose. Chip urethane is known as a recycled product of a conventional crushed urethane foam, but since the crushed urethane used is large, it is not possible to mold a product having a complicated shape, and its use is limited. .. On the other hand, the resin molded product according to the present invention can be processed into a complicated shape by using a powdery foamed resin having a size of 50 μm or more and 1000 μm or less as a raw material foamed resin.

When the average particle size of the foamed resin used as the material of the resin molded product is 2000 μm or more and 8000 μm or less, a resin molded product that can be preferably used as a sound absorbing material or a water absorbing material can be produced, and particularly in a low frequency region. It is a resin molded product with excellent sound absorption coefficient.
Even when the average particle size of the foamed resin used as the material of the resin molded product is 50 μm or more and 1000 μm or less, it is possible to produce a resin molded product that can be preferably used as a sound absorbing material or a water absorbing material, and is particularly excellent in water retention. It becomes a resin molded body.
In the case of producing the resin molded product according to the present invention, a foamed resin having an average particle size of 2000 μm or more and 8000 μm or less and a foamed resin having an average particle size of 50 μm or more and 1000 μm or less are mixed and produced. May be 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 layers.
As for the laminated resin molded product, for example, as described above, a layered resin molded product is produced using the foamed resin of the present invention as a material by using a known chip urethane manufacturing facility, and another such as having at least one layer thereof. It may be laminated with the layered resin molded body. For example, by laminating a resin molded body manufactured using a foamed resin having an average particle size of 2000 μm or more and 8000 μm or less and a resin molded body manufactured using a foamed resin having an average particle size of 50 μm or more and 1000 μm or less. , A laminated resin molded product having the characteristics of both resin molded products can be obtained.

[Sound absorbing material]
The sound absorbing material according to the present invention is characterized in that the foamed resin, resin molded product or laminated resin molded product according to the present invention is used.
In general, the sound absorbing effect of a sound absorbing material is exhibited by absorbing the vibration energy of sound and converting it into heat energy. In the sound absorbing material using the foamed resin, the foamed resin itself is an elastic body and easily absorbs energy, and the foamed resin itself vibrates macroscopically due to the miniaturization. It is considered that the synergistic effect of these two phenomena exerts an excellent sound absorption effect particularly in the high frequency region of 2000 Hz or higher. In particular, a sound absorbing material using a foamed resin having an average particle size of 50 μm or more and 1000 μm or less exhibits a sound absorbing coefficient equivalent to that of Thinsulate (a sound absorbing and insulating material manufactured by 3M), which has a proven track record as a sound absorbing material in a high frequency region.
Further, 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 to produce a sound absorbing effect by receiving a low-frequency sound wave having a long wavelength on a continuous surface of the resin molded body or the laminated resin molded body. In the low frequency region, a resin molded product produced by using a foamed resin having an average particle size 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 also be preferably used as a sound absorbing and heat insulating material for, for example, refrigerators and vending machines.

[Water absorbing material]
The water absorbing material according to the present invention is characterized by using a foamed resin, a resin molded product or a laminated resin molded product according to the present invention.
As described above, the foamed resin according to the present invention has a structure in which bubbles are connected to each other by microcavities. Therefore, the water-absorbing material using the foamed resin has high water absorption, and further, it is difficult for the once absorbed water to be released, and it has excellent water retention properties. It is considered that this is because water is absorbed by the bubble portions connected by the capillary phenomenon, while the water absorbed by the surface tension of water is retained as it is. In particular, in the foamed resin having an average particle size of 50 μm or more and 1000 μm or less, the diameter of the fine cavity converges to a small size of about 1 to 2 μm, so that the water absorbed by the capillary phenomenon is dissipated by the surface tension of water. It is hard to be done.
Further, the water absorbing material using the resin molded body or the laminated resin molded body also has excellent water absorption rate and water retention.
The water-absorbing material according to the present invention can be used, for example, as a planter for growing plants and a humidity control material. Due to its excellent water retention effect, it can be preferably used for growing plants, and can also be applied to greening of the roof of a building.
The present invention may also adopt the following configurations.
(1) A foamed resin having a structure in which at least a part of independent bubbles are connected by the action of microorganisms, and has 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 a part of independent bubbles are connected by the action of microorganisms, and has an average particle size of 50 μm or more and 1000 μm or less.
(3) The foamed resin according to the above (1) or (2), 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 resolution.
(5) A resin molded product obtained by molding the foamed resin according to the above (1) and / or the above (2).
(6) A laminated resin molded product having at least one layer of a foamed resin molded product obtained by molding the foamed resin according to the above (1) and / or the above (2) in a layered manner.
(7) The use of the foamed resin according to any one of (1) to (4) above, the resin molded product according to (5) above, or the laminated resin molded product according to (6) above. Characteristic sound absorbing material.
(8) The use of the foamed resin according to any one of the above (1) to (4), the resin molded product according to the above (5), or the laminated resin molded product according to the above (6). Characteristic water absorbing material.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[Example 1]
(Material to be treated)
The waste urethane foam used for the steering of automobiles was crushed to a size of about 5 mm square and used as the material to be treated.
A cutting mill SM300 manufactured by Verder Scientific Co., Ltd. (formerly Lecce Co., Ltd.) was used for crushing the waste urethane foam material.
(Unsaturated fatty acid)
Oleic acid (manufactured by Wako Pure Chemical Industries, Ltd., grade: Wako first grade) was used as the unsaturated fatty acid.
(Microorganisms)
As a microorganism capable of adsorbing and decomposing urethane, a microorganism (strain: C13a) specified by the accession number FERM P-21770 was used.

(Culture medium)
As the medium for culturing the microorganism, a YES-G medium prepared as follows was used.
A KH ₂ PO ₄ solution and a Na ₂ HPO ₄ solution having the concentrations shown in Table 1 below were prepared, and 10 mL and 40 mL, respectively, were mixed to obtain Solution A. The other Solution B, Solution C, and Solution D were prepared as solutions having the compositions shown in Table 1 below. The prepared Solutions A to D were sterilized at 121 ° C. for 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.

-The process of treating the material to be treated with unsaturated fatty acids-
Oleic acid diluted with 99% ethanol to a concentration of 10% (W / W) was prepared and added to a 100 mL Erlenmeyer flask.
About 4 g 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 for washing with ultrasonic waves. The material to be treated was taken out from the Erlenmeyer flask, and further washed with distilled water. Then, it was sufficiently dried at 40 ° C. and sterilized at 121 ° C. for 20 minutes.

-Process of allowing microorganisms to act on the material to be treated-
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 cultured with shaking to obtain a main culture bacterial solution. The culture conditions were 40 ° C., 140 rpm, and 9 days.
50 mL of the main culture bacterial solution was added to a 100 mL Erlenmeyer flask containing the material to be treated prepared above, and the cells were cultured with shaking. The culture conditions were 40 ° C. and 80 rpm.
The period of action of microorganisms was one week.

-Washing process-
After each culture period, the bacterial solution was discarded, 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 sufficiently dried at 40 ° C. (over night).
As a result, a particle-shaped foamed resin (hereinafter referred to as "particle product") having a structure in which at least a part of independent bubbles are connected by the action of microorganisms and having an average particle size of 5000 μm was obtained. The particle product was reduced by 3% by mass with respect to the weight before treatment.
The average particle size of the foamed resin was measured using a laser analysis scattering type particle size distribution measuring device LA960 (manufactured by Horiba Seisakusho Co., Ltd.). Sampling was performed by wet measurement using distilled water as a medium.

[Example 2]
The particle product obtained in Example 1 was pulverized using an ultracentrifuge crusher (Rotmill ZM200) manufactured by Verder Scientific Co., Ltd. (formerly Lecce Co., Ltd.).
Unlike the conventional urethane foam having independent bubbles, it can be easily pulverized even at room temperature, and a powder-like foamed resin having an average particle size of 300 μm (hereinafter referred to as “powder product”) can be obtained.

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

[Example 4]
A resin molded product as shown in FIG. 6 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 (hereinafter, referred to as “powder molded product”). Manufactured.

-Evaluation-
<Microscopic observation>
The state of the cells of the particle product obtained in Example 1 was observed with a microscope. The result is shown in FIG. 1 (B). As shown in FIG. 1 (B), fine cavities having a diameter of about 1 μm to 10 μm were observed on the wall surface of the independent bubbles. In addition, it was observed that the microcavities invaded the inside of the cell.
Similarly, the state of the cells 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 surface of the independent air bubbles of the powder product were made uniform to have a diameter of about 1 μm. This is because, in the process of manufacturing the powder product, the fine cavity portion having a relatively large diameter of the particle product was the starting point and broke.

<Sound absorption characteristics>
(Foam 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 in accordance with ISO 10534-2 and ASTM E 1050 using a vertical incident sound absorption coefficient measurement system (DS2000) manufactured by Ono Sokki Co., Ltd.
Specifically, a system that radiates sound waves into the tube from a speaker built in the end of the acoustic impedance tube, measures the transfer function between two microphones in the tube, and calculates the vertically incident sound absorption coefficient, reflectance coefficient, and standardized impedance. Is. The specifications of the acoustic impedance tube were changed in the high frequency region and low frequency region. The B tube in the high frequency region had a length of 500 mm and an inner diameter of 29φ, and the A tube in the low frequency region had a length of 835 mm and an inner diameter of 100φ.
The measurement result in the high frequency region is shown in FIG. 7, and the measurement result in the low frequency region is shown in FIG.

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

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

(Resin molded product)
The sound absorption characteristics of the particle molded product obtained in Example 3 and the powder molded product obtained in Example 4 in the low frequency region were evaluated in the same manner as in the above foamed resin. The result is shown in FIG.
As shown in FIG. 9, in the case of the resin molded product, improvement in sound absorption characteristics in the low frequency region, which was difficult with the particle product and the powder product, was observed. It is considered that this is because the sound absorbing effect is obtained by receiving low-frequency sound waves having a long wavelength on the continuous surface of the resin molded body and swinging the entire surface of the resin molded body. Further, since the surface of the particle molded product is uneven, it is considered that the sound absorbing 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 about once every few hours. , Water was absorbed for 24 hours. After 24 hours, the test piece was taken out, placed on a sieve inclined at about 45 ° from the vertical and left to stand for 30 seconds, and then the mass of each was measured in units of 0.01 g. This was taken as the amount of water absorption, converted into ² per 100 cm of surface area, and the average of 3 points was calculated and evaluated.
The result of the water absorption test is shown in FIG. In addition, in FIG. 10, "sponge" means a so-called sponge of a foamed resin having communicated pores, and "free foamed product" means urethane foam having independent bubbles.

(Water retention test)
A wire mesh was placed on the absorbent cotton so that the test piece and the absorbent cotton did not come into direct contact with each other, and the water-absorbed test piece used in the water absorption test was placed on the test piece, and the weight was measured over time. In the water absorption test, a test piece showing a water absorption amount closest to the average value of the water absorption amount was used as a test piece for the water retention test. At the time of measurement, the top and bottom of the test piece were determined, and the measurement was always performed with the same side facing down.
The result of the water retention test is shown in FIG. In FIG. 11, “sponge” and “free foam” mean the same as in FIG.

As shown in FIGS. 10 and 11, it was confirmed that both the particle molded product and the powder molded product were 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 diameter of fine cavities of about 1 to 2 μm, so that the water absorbed by the capillary phenomenon is more than that of the particle molded product due to the surface tension of water. It is probable that it became difficult to dissipate.

Claims (2)

A method for producing a foamed resin for a sound absorbing material or a water absorbing material, which has a structure in which at least a part of independent bubbles are connected by the action of microorganisms and has an average particle size of 2000 μm or more and 8000 μm or less.
The foamed resin is urethane foam,
The process of treating urethane foam with independent bubbles with unsaturated fatty acids,
A step of allowing a microorganism belonging to the genus Streptomyces having urethane resolution to act on the urethane foam treated with the unsaturated fatty acid to form a structure in which at least a part of independent bubbles of the urethane foam are connected. When,
A step of pulverizing urethane foam after allowing the microorganisms to act so that the average particle size is 2000 μm or more and 8000 μm or less.
Have,
Microcavities of 1 μm or more and 10 μm or less are formed on the wall surface of the cells in the portion where the independent cells are connected to each other.
A method for producing a foamed resin for a sound absorbing material or a water absorbing material. A method for producing a foamed resin for a sound absorbing material or a water absorbing material, which has a structure in which at least a part of independent bubbles are connected by the action of microorganisms and has an average particle size of 50 μm or more and 1000 μm or less.
The foamed resin is urethane foam,
The process of treating urethane foam with independent bubbles with unsaturated fatty acids,
A step of allowing a microorganism belonging to the genus Streptomyces having urethane resolution to act on the urethane foam treated with the unsaturated fatty acid to form a structure in which at least a part of independent bubbles of the urethane foam are connected. When,
A step of pulverizing urethane foam after allowing the microorganisms to act so that the average particle size is 50 μm or more and 1000 μm or less.
Have,
Microcavities of 1 μm or more and 10 μm or less are formed on the wall surface of the cells in the portion where the independent cells are connected to each other.
A method for producing a foamed resin for a sound absorbing material or a water absorbing material.