JP2011241262A - Biodegradable porous body and water-absorbing material using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new biodegradable porous body obtained by a simple method, having an open-cell structure and further having water-absorbing properties, and to provide a water-absorbing material using the porous body.SOLUTION: The open-cell porous body comprising a powder having ≥0.001 g/cmand ≤0.1 g/cmof bulk density, and a binder component is regulated so that the melting point or the softening point of the binder component may be lower than the melting point or the softening point of the powder, and the porous body may contain ≥1 pt.wt. and ≤30 pts.wt. of a surfactant based on 100 pts.wt. of the powder.

Description

  The present invention relates to an open-cell porous body and a water-absorbing material using the open-cell porous body.

  The porous body is a solid having a large number of cavities filled with bubbles inside. Well, a structure in which cavities are connected to each other is called an open cell structure, and a porous body having such an open cell structure often has a property of absorbing liquid (water absorption).

  For example, polyurethane foam having an open cell structure is widely used as a sponge for washing dishes by utilizing its water absorption. In addition, polyurethane foam or phenol foam having an open cell structure is used as a flower arrangement pedestal. This utilizes its water absorption and has a function of holding fresh flowers without dying over a long period of time. Furthermore, in the agricultural field, a porous body obtained by solidifying rock wool has been used as a medium used in hydroponics and the like. The porous body used in this application retains the root of the plant to be cultivated, and has a function of sucking up water containing nutrients and supplying it to the root. Thus, a porous body having the property of absorbing liquid is extremely useful.

  As a proposal of an open-cell porous body, for example, Patent Document 1 discloses a polylactic acid porous body having a continuous pore having an average pore diameter of 1 to 30 μm and made of a polymer mainly composed of lactic acid. The porous body is prepared by dissolving a polymer containing lactic acid as a main component, a water-soluble polyalkylene ether and a copolymer of lactic acid in a solvent to form a solution, drying the solution to obtain a solid, and then another liquid. And the copolymer is eluted. However, the manufacturing method has a problem that the procedure is extremely complicated and the cost tends to increase. Moreover, although a film-like thing can be obtained, there exists a problem that a communicating structure is easy to change at the time of drying, and it is difficult to obtain a comparatively thick thing.

  Patent Document 2 discloses that a biodegradable plastic is mixed or kneaded with an organic foaming agent, water, and natural fiber, and then placed in a mold and heated and foamed in the mold, or after kneading and extrusion, the pressure is released. An open-cell body made mainly of at least one biodegradable plastic manufactured by a method such as foaming is disclosed.

JP 2006-306983 A JP 2000-217683 A

  An object of the present invention is to provide a novel porous body having an open-cell structure and water absorption and a water-absorbing material using the same by a simple method.

  As a result of intensive studies on the above problems, the inventors of the present invention have found that an open-cell porous material composed of a powder having a low bulk density, a binder component having a specific melting point or softening point, and a surfactant has a volume shrinkage of the powder. Thus, the present invention has been completed by finding that it can be thermoformed and has good water absorption and moderate brittleness.

The first aspect of the present invention is an open-cell porous body comprising a powder having a bulk density of 0.001 g / cm ³ or more and 0.1 g / cm ³ or less, a binder component, and a surfactant. The melting point or softening point of the binder component is lower than the melting point or softening point of the powder and contains 1 part by weight or more and 30 parts by weight or less of the surfactant with respect to 100 parts by weight of the powder. The present invention relates to an open-cell porous body.

As a preferred embodiment,
(1) The powder is polylactic acid,
(2) The bulk density is 0.01 g / cm ³ or more and 0.2 g / cm ³ or less,
(3) A powder having a bulk density of 0.001 g / cm ³ or more and 0.1 g / cm ³ or less and a binder component are obtained by fusing each other by heating.
(4) The powder is subjected to hydrolysis treatment.
The present invention relates to the open-cell porous body described above.

The open-cell porous body of the present invention is obtained by a simple method, exhibits excellent water absorption, and has a uniform open-cell structure throughout.
Since the open-cell porous body of the present invention has high water absorption, it can be preferably used as a pedestal for flower arrangements or a plant culture medium.

The open-cell porous body of the present invention comprises a powder and a binder component having a bulk density of 0.001 g / cm ³ or more and 0.1 g / cm ³ or less, and is 1 to 30 parts by weight with respect to 100 parts by weight of the powder. Part or less of a surfactant.

The bulk density of the powder constituting the open-cell porous body of the present invention is 0.001 g / cm ³ or more and 0.1 g / cm ³ or less, preferably 0.002 g / cm ³ or more and 0.05 g / cm ^3. It is as follows. If the bulk density of the powder is less than 0.001 g / cm ³ , the strength of the molded product obtained using the powder tends to decrease, and if it exceeds 0.1 g / cm ³ , the powder is used. Not only does the weight of the resulting molded body increase, but the continuous internal cavity volume per unit volume tends to decrease.
The bulk density of the powder is measured according to JIS K6911 and can be calculated based on the following formula (1).
Bulk density of powder (g / cm ³ ) = [mass of graduated cylinder with sample (g) −mass of graduated cylinder (g)] / [volume of sample (cm ³ )] (1)

  The powder used in the present invention is not particularly limited as long as the powder has a predetermined bulk density, but the foam is pulverized from the point that the bulk density of the powder can be easily adjusted widely. It is preferable to obtain by doing.

  The pulverization process used in the present invention can be easily performed using a known technique. Preferable specific examples include a method using a pulverizer such as a jet mill, a cutter mill, a ball mill, a spiral mill, and a hammer mill. At this time, a method of screening the processed product after passing through the pulverizer and selecting only the sufficiently fine powder may be used in combination. Further, for the purpose of preventing the melting of the base resin during pulverization, a method of cooling the foam or pulverizer is also preferably used.

  When the powder used in the present invention is obtained by crushing a foam, the bulk density of the powder tends to depend on the density of the foam used for the crushing and the shape of the powder. The smaller the density and the larger the aspect ratio of the powder, the smaller the tendency.

  The powder obtained by pulverizing the foam in the present invention tends to have a fine structure in which flakes are connected, and can have a low bulk density. In this case, not only is the open-cell porous body lighter, but also the internal continuous cavity ratio can be increased, so that the amount of water absorption per volume can be significantly increased.

In the present invention, in order to obtain a powder having a fine structure in which flakes are connected, the average cell diameter of the foam used is preferably 100 μm or more and 1000 μm or less, more preferably 150 μm or more and 700 μm or less. When the average cell diameter of the foam is less than 100 μm, the powder contains closed cells and the water absorption tends to decrease. On the other hand, if the average bubble diameter exceeds 1000 μm, the bulk density of the powder tends to increase.
The average cell diameter of the foam is obtained by photographing the cell structure of the foam with an electron microscope, calculating the length per cell in accordance with ASTM: D3576-94, and multiplying the cell size by 1.5. It is a value.

  The average outer diameter of the powder in the present invention varies depending on the properties of the porous body to be obtained, but is preferably 100 μm or more and 2000 μm or less.

  The “average outer diameter” as used in the present invention refers to the diameter at which the cumulative percentage is 50% in the mass-based particle size distribution of the dry sieving particle size determined by the dry sieving test method defined in JIS K0069. Specifically, in the figure where the cumulative percentage (%) for each sieve opening obtained by the above test using the standard sieve specified in JIS Z8801-1 is plotted, and each store is connected by a straight line, The average outer diameter is determined with the value of the opening with a percentage of 50%.

  Examples of the powder suitably used in the present invention include polyethylene resins, polypropylene resins, polystyrene resins, polyamide resins, polyether resins, acrylic resins, vinyl resins, cellulose and derivatives thereof, and aromatic polyester types. Examples thereof include resins and aliphatic polyester resins, and aliphatic polyester resins are preferable because they exhibit thermoplasticity and have relatively good processability. In addition, since aliphatic polyester-based resins tend to exhibit good biodegradability, they are suitable because they do not require special treatment when disposed of after being used for agricultural and horticultural materials such as pedestals for flower arrangements. Can be used.

  The aliphatic polyester resin in the present invention refers to an aliphatic polyester as a main component (50% by weight or more). For example, polylactic acid resin including polylactic acid as a main component, poly-3- (hydroxybutyrate). ), Poly-3- (hydroxybutyrate-covalylate), poly-3- (hydroxybutyrate-cohexanoate) and other hydroxy acid polycondensates, and ring-opening polymers of lactones such as polycaprolactone, poly Examples thereof include polycondensates of aliphatic polyhydric alcohols such as butylene succinate, polybutylene adipate, polybutylene succinate adipate, poly (butylene adipate / terephthalate) and the like, and at least selected from these groups One type can be used. Further, two or more aliphatic polyester resins can be mixed and used.

  Among these, in order to obtain the effects of the present invention, as the aliphatic polyester-based resin, a polylactic acid-based resin or a hydroxy acid polycondensate is preferable, and a polylactic acid-based resin is particularly preferable because it is environmentally friendly.

  The polylactic acid resin in the present invention is not particularly limited, but it is preferable that the main component is polylactic acid whose isomer ratio of the lactic acid component is 5% or more, preferably 8% or more. If the isomer ratio is within this range, the polylactic acid-based resin is amorphous, which is preferable because it is easy to obtain a low-density foam from the viewpoint of foamability and moldability.

  Next, the case where powder is manufactured using a foam will be described.

First, a foam is manufactured using the resin.
Any known production method is preferably used as the method for producing the foam. For example, the extrusion foaming method described in Japanese Patent No. 2005-162804 and the bead method described in Japanese Patent No. 2004-149649 can be applied.

  In addition, the foam obtained as described above may be further subjected to a hydrolysis treatment for the purpose of adjusting the hardness (brittleness).

  The hydrolysis method and conditions are not particularly limited as long as the hydrolysis proceeds uniformly, but the treatment in the soil is extremely long in hydrolysis time, whereas the hydrolysis does not easily occur uniformly. Hydrolysis using high-penetration water vapor or a constant temperature / humidity machine is preferred for foamed molded products using amorphous aliphatic polyester resins as base resins, from the viewpoint of processing uniformity and ease of control. A method using a constant temperature and humidity machine is more preferable.

  When the hydrolysis is performed using a thermo-hygrostat, a foamed molded article having an amorphous aliphatic polyester resin as a base resin is preferably 60 ° C. or higher and 100 ° C. or lower and a relative humidity of 60% or higher, more preferably 60 ° C to 100 ° C, relative humidity 60% to 100%, more preferably 60 ° C to 95 ° C, relative humidity 60% to 100%, preferably 3 hours to 48 hours, The treatment is preferably performed for 4 hours or more and 24 hours or less.

  In the present invention, the shape of the foam is not particularly limited, and any of particles, sheets, and blocks is preferably used. Of these, the subsequent pulverization step is facilitated. Therefore, it is preferably in the form of particles.

The density of the foam used used in the present invention ^is preferably ^{0.001g / cm 3 ~0.1g / cm 3} .

  The open-cell porous body of the present invention has a tendency to be able to solidify the entire molded body by including a binder component having a melting point or softening point lower than the melting point or softening point of the powder, and a heat treatment described later. The temperature can be suppressed below the temperature at which the powder melts or softens, and the shrinkage of the powder can be suppressed.

  The melting point of the powder and the binder component is a temperature showing the maximum peak top in the heat of fusion curve obtained when the temperature is raised from 0 to 200 ° C. at a rate of temperature increase of 10 ° C./min in the differential scanning calorimetry. is there. The softening point of the powder and binder component is a temperature measured according to JIS K5902.

  The binder component content in the open-celled porous body of the present invention is preferably 5 parts by weight or more and 70 parts by weight or less, more preferably 10 parts by weight or more and 60 parts by weight or less with respect to 100 parts by weight of the powder. The amount is more preferably 10 parts by weight or more and 50 parts by weight or less. When the content of the binder component is within the range, shrinkage can be suppressed and an open-cell porous body having moderate brittleness can be obtained.

  The binder component used in the present invention is not particularly limited as long as its melting point or softening point is lower than the melting point or softening point of the powder, but as a preferred specific example, polyolefin resin such as low density polyethylene Glycerol fatty acid esters such as glycerol monostearate, glycerol distearate, glycerol monopalmitate, glycerol dipalmitate, glycerol monobehenate, glycerol dibehenate, glycerol monolaurate; sorbitan stearate, sorbitan tristearate, Sorbitan fatty acid esters such as sobubitan palmitate; ring-opening polymer such as polycaprolactone; polybutylene succinate, polybutylene adipate, polybutylene succinate adipate, poly (butylene adipate) / Terephthalate) polycondensates of an aliphatic polyhydric alcohol and aliphatic carboxylic acids such as, and the like; rosins, rosin esters, natural resins such as shellac. These may be used alone or in combination of two or more. Among these, glycerin fatty acid ester and polycaprolactone are preferable because they are relatively safe and easy to handle.

  The shape of the binder component in the present invention under normal temperature and normal pressure is preferably a solid such as powder or flake.

  In the present invention, the method of mixing the binder component with the powder is not particularly limited. However, as a preferred specific example, the foam and the binder component are supplied to the pulverization step to pulverize the foam and simultaneously mix the binder component. For example, a method for blending the powder and the binder component in powder form, and a method for blending the powder by mixing a solution in which the binder component is dissolved in a solvent.

  The open-cell porous body of the present invention comprises 1 to 30 parts by weight, preferably 1 to 20 parts by weight of a surfactant with respect to 100 parts by weight of the powder. The amount and water absorption rate can be greatly increased. When the surfactant content is less than 1 part by weight, there is a tendency that the effect of improving the water absorption amount and the water absorption rate cannot be obtained. When the surfactant content exceeds 30 parts by weight, the strength of the porous body after water absorption is poor. It will be enough.

  In the present invention, there is no particular limitation on the method of adding the surfactant. As a specific example of a preferred method, a method of mixing the surfactant, the powder and the binder component before obtaining an open-cell porous body. And a method in which a surfactant is kneaded in advance into a base resin constituting the powder.

  As the surfactant used in the present invention, any kind of an anionic surfactant, a cationic surfactant, an amphoteric surfactant, and a nonionic surfactant can be suitably used. Among these, anionic surfactants and nonionic surfactants are preferred because they are relatively safe and inexpensive.

  Specific examples of the surfactant preferably used in the present invention include, for example, sodium aliphatic acid, potassium aliphatic acid, sodium alkylbenzene sulfonate, potassium alkylbenzene sulfonate, higher alcohol sodium sulfate, higher alcohol potassium sulfate, alkyl ether sulfate. Anionic interfaces such as sodium ester ester, potassium alkyl ether sulfate, α-sulfoaliphatic ester, sodium α-olefin sulfonate, potassium α-olefin sulfonate, sodium monoalkyl sulfate, potassium monoalkyl sulfate, sodium monoalkyl phosphate Activating agent; cationic surface activity such as alkyltrimethylammonium chloride, dialkyldimethylammonium chloride, alkylbenzyldimethylammonium chloride Agents; amphoteric surfactants such as alkylcarboxybetaines; polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol ethers, alkyl glucosides, polyoxyethylene fatty acid esters, polyoxyethylene difatty acid esters, sucrose fatty acid esters, sorbitan fatty acid esters, poly And nonionic surfactants such as oxyethylene sorbitan fatty acid ester, fatty acid diethanolamide, and alkyl monoglyceryl ether. These may be used alone or in combination of two or more.

  The open-cell porous body of the present invention can be obtained by fusing powder and a binder component.

  In the present invention, the method for fusing the powder and the binder component is not particularly limited, but a preferable example is a method for fusing the powder and the binder component by heat. As a specific example of the method of fusing powder and binder component by heat, a mixture of powder, binder component and surfactant is put in a mold and treated for a predetermined time at a temperature at which the binder component melts but the powder does not melt. Method, etc.

  The above heat treatment temperature varies depending on the type of base resin constituting the powder, the type of binder component, and the shape and size of the open-cell porous body to be obtained. preferable. When the heat treatment temperature is less than 60 ° C., the binder component is not sufficiently melted, and a molded product tends to be not obtained. Moreover, when the temperature of heat processing exceeds 120 degreeC, there exists a tendency for the density of a porous body to become high easily and to become an open-cell porous body with inferior water absorption.

  The above heat treatment time varies depending on the type of base resin constituting the powder, the type of binder component, and the shape and size of the open-cell porous body to be obtained, and further the processing temperature, the processing method, etc. It is preferably 5 minutes or more and 10 hours or less. When the heating time is shorter than 5 minutes, the binder component is not sufficiently melted, and there is a tendency that a molded product cannot be obtained. Moreover, when heat processing time exceeds 10 hours, the obtained open-cell porous body shrink | contracts with time, and there exists a tendency for a density to become high.

  In the present invention, various additives, specifically, inorganic substances such as pigments, dyes, talc, calcium carbonate, borax, zinc borate, aluminum hydroxide, calcium stearate, as long as the effects of the present invention are not impaired. It may contain flame retardants, antistatic agents, weathering agents, fillers, antifogging agents, antibacterial agents, lubricants, and the like. Various additives can be added by mixing with the powder and the binder component or by mixing in advance with the base resin of the powder.

The bulk density of the open-cell porous body of the present invention is preferably 0.01 g / cm ³ or more and 0.2 g / cm ³ or less, preferably 0.02 g / cm ³ or more, in terms of light weight and excellent water absorption. More preferably, it is 0.15 g / cm ³ or less.

  The open cell ratio of the open cell porous material of the present invention is preferably 80% or more and 100% or less, and more preferably 90% or more and 100% or less. When the open cell ratio is less than 80%, the amount of water absorption tends to decrease because there are few continuous internal cavities inside the molded body.

  The open cells in the open cell porous body of the present invention are preferably uniform throughout. In addition, it can be evaluated that open-cells are uniform over the whole by cutting out a sample piece from the surface layer part and the center part of the molded body, and measuring the respective open-cell ratios. The open cell ratio of the open cell porous material of the present invention is preferably in the range of 80% or more and 100% or less for both the surface layer portion and the center portion.

  The open-cell porous body of the present invention has a low density and can easily have uniform open cells throughout, and as a result, has a structure that easily exhibits good liquid absorbency. Furthermore, by incorporating a specific amount of a surfactant into the open-celled porous body having the above structure, it becomes possible for the first time to exhibit extremely excellent water absorption. Therefore, the open-cell porous body of the present invention can be suitably used as a water-absorbing material.

  The water-absorbing material in the present invention refers to a material that naturally permeates into the interior and that itself retains the permeated water by contacting with water at normal temperature and pressure. Furthermore, the water-absorbing material of the present invention exhibits water absorption based on a physical phenomenon such as a so-called capillary phenomenon, so that the water holding power is moderately weak. It has a characteristic that can be released.

  Specific examples of the use of the water-absorbing material using the continuous porous material of the present invention include a flower arrangement pedestal, a plant culture medium, a soil conditioner and the like, which are preferably used.

  When using for the said use, there is no restriction | limiting in particular about the shape of an open-cell porous body, It can be set as a suitable shape according to uses, such as a block form and a sheet form.

Hereinafter, although the base for flower arrangements of this invention is demonstrated in detail by a specific Example, this invention is not limited only to this Example.
Unless otherwise specified, “part” and “%” are based on weight.

<Measurement of bulk density of porous porous body>
The obtained open-cell porous body was cut into 5 cm square, its weight (g) was measured, and calculated according to the equation (2).
Bulk density (g / cm ³ ) = [weight of cube (g)] / [125 (cm ³ )] (2)

<Measurement of open cell ratio of open cell porous body>
The surface layer part and the center part of the obtained open-cell porous body were cut out, and measured according to ASTM D-2856 using an air comparison type hydrometer (1000 type, manufactured by Tokyo Science Co., Ltd.). When the open cell ratio of the surface layer part and the central part is 80% or more and 100% or less, the open cell ratio is assumed to be uniform throughout.

<Water absorption test of open-cell porous body>
The obtained open-cell porous body was cut into a 3 cm square and its weight was measured. Next, the porous body was allowed to stand on the surface of tap water placed in a cup to absorb water. The weight of the porous body that was allowed to absorb water for 5 minutes was measured, and the weight ratio before and after water absorption was calculated as water absorption according to the formula (3).
Water absorption (g / g) = [weight after water absorption (g)] / [weight before water absorption (g)] (3)

<Evaluation of brittleness of open-cell porous body>
The brittleness was evaluated as follows by vertically inserting a gerbera having a stem having a diameter of 2 mm into the obtained continuous porous body.
○: The stem does not break or bend, and there is no resistance.
Δ: The stem does not break or bend, but there is resistance to insertion.
X: The tip of the stem is crushed, the stem is broken, and it is not allowed.

Example 1
[Production of expanded particles]
Biaxial extrusion of 100 parts by weight of amorphous polylactic acid resin with a D-form ratio of 10%, MI value of 3.7 g / 10 min and 2.0 parts by weight of polyisocyanate compound [manufactured by Nippon Polyurethane Co., Ltd., MR-200] Using a machine (Toshiba Machine, TEM35B), melt kneading was performed at a cylinder temperature of 185 ° C., and using an underwater cutter, approximately 1 mmφ (about 1.5 mg) bead-shaped polylactic acid resin particles were obtained.
With respect to 100 parts by weight of the obtained polylactic acid resin particles, 100 parts by weight of water, 12 parts by weight of deodorized butane (normal butane / isobutane weight ratio = 7/3) as a foaming agent, 10 parts by weight of sodium chloride, and a dispersion aid As an example, 0.3 part by weight of polyoxyethylene oleyl ether was charged into an autoclave and maintained at 84 ° C. for 90 minutes. It was taken out after being sufficiently cooled and dried to obtain amorphous polylactic acid-based resin foamable particles. The resulting polylactic acid-based resin expandable particles had a blowing agent impregnation rate of 5.5%.
The obtained polylactic acid-based resin expandable particles are put into a pre-foaming machine (DHP Co., Ltd., BHP-300) and held under steam at 90 ° C. for 40 to 60 seconds to obtain polylactic acid-based resin expanded particles. It was. The obtained polylactic acid-based resin foamed particles were air-dried, and then the fused particles were separated and removed using a sieve having an opening of 5.60 mm. The bulk magnification of the polylactic acid-based resin expanded particles passed and sorted was 0.025 g / cm ³ and the average cell diameter was 400 μm.
[Preparation of powder]
The obtained foamed particles are wetted with water, pulverized using a cutter mill [manufactured by Tescom, Mill & Mixer TML160] as a pulverizer, vacuum-dried in a vacuum dryer at 40 ° C., and then using a sieve having an opening of 800 μm. Thus, a passed powder was obtained. The bulk density of the obtained powder was 0.031 g / cm ³ and the softening point was 120 ° C.
[Preparation of open-cell porous body]
20 parts by weight of glycerin monostearate [manufactured by Riken Vitamin Co., Ltd., Riquemar S-100P, melting point 70 ° C.] as a binder component, and α-olefin sodium sulfonate as a surfactant with respect to 100 parts by weight of the obtained powder [Lion Co., Ltd., Liporan PJ-400] 3 parts by weight was added and mixed well. 30 g of the obtained mixture was scraped into an aluminum mold (7 cm square) to the full and heat-treated at 100 ° C. for 5 hours to obtain an open-cell porous body.
The resulting open-cell porous body was subjected to bulk density measurement, open-cell ratio measurement, water absorption test, brittleness evaluation, and shrinkage evaluation. The results are shown in Table 1.

(Example 2)
In [Preparation of open-cell porous body], an open-cell porous body was obtained in the same manner as in Example 1 except that the addition amount of glycerol monostearate was changed to 50 parts by weight.
The resulting open-cell porous body was subjected to bulk density measurement, open-cell ratio measurement, water absorption test, brittleness evaluation, and shrinkage evaluation. The results are shown in Table 1.

(Example 3)
In [Preparation of open-cell porous body], open-cell porous material was obtained in the same manner as in Example 1 except that the binder component was changed to 20 parts by weight of polycaprolactone (manufactured by Wako Pure Chemical Industries, Ltd., melting point 60 ° C., Mw = 10000). A mass was obtained.
The resulting open-cell porous body was subjected to bulk density measurement, open-cell ratio measurement, water absorption test, brittleness evaluation, and shrinkage evaluation. The results are shown in Table 1.

Example 4
In [Production of Expanded Particles], the obtained polylactic acid-based resin expanded particles were controlled at a temperature of 80 ° C. and a relative humidity of 95% [manufactured by Isuzu Seisakusho, program temperature and humidity controller, HPAV-120-40 type] ] Was allowed to stand for 24 hours, and an open-cell porous body was obtained in the same manner as in Example 1 except that the hydrolysis treatment was performed.
The resulting open-cell porous body was subjected to bulk density measurement, open-cell ratio measurement, water absorption test, brittleness evaluation, and shrinkage evaluation. The results are shown in Table 1.

(Comparative Example 1)
In [Preparation of open-cell porous body], an attempt was made to obtain an open-cell porous body in the same manner as in Example 1 except that glycerin monostearate as a binder component was not used. It could not be solidified.

(Comparative Example 2)
In [Preparation of powder], the polylactic acid-based resin expanded particles obtained in Example 1 as a pulverizer were pulverized using an ultracentrimill [manufactured by Nippon Coke Industries, Ltd., UCM type]. In the same manner as in Example 1, powder was obtained, and an open-cell porous body was obtained. The bulk density of the obtained powder was 0.33 g / cm ³ . The resulting open-cell porous body was subjected to bulk density measurement, open-cell ratio measurement, water absorption test, brittleness evaluation, and shrinkage evaluation. The results are shown in Table 1.

(Comparative Example 3)
In [Production of open-cell porous body], rosin ester (Arakawa Chemical Industries, Ltd., S-EA125, softening point 125) as a binder component (component) with respect to 100 parts by weight of the powder obtained in Example 4. C.) 20 parts by weight and 3 parts by weight of α-olefin sulfonic acid sodium salt (Lipolan PJ-400 manufactured by Lion Corporation) were added and mixed well.
The obtained mixture was put into an aluminum mold (7 cm square) and heat-treated at 130 ° C. for 5 hours to obtain an open-cell porous body. I couldn't get a body.

From the results shown in Table 1, it can be confirmed that the open-cell porous body containing the binder component and the surfactant obtained in the Examples and having a low bulk density exhibits high water absorption. In addition, as shown in Example 4, an open-cell porous body using a powder obtained from hydrolyzed foamed particles is suitably used as a flower arrangement pedestal because it exhibits moderate brittleness. I was able to confirm.

Claims (6)

An open-cell porous body comprising a powder having a bulk density of 0.001 g / cm ³ or more and 0.1 g / cm ³ or less, a binder component, and a surfactant,
The melting point or softening point of the binder component is lower than the melting point or softening point of the powder, and the surfactant is contained in an amount of 1 to 30 parts by weight with respect to 100 parts by weight of the powder. Cellular porous body.   2. The open-cell porous body according to claim 1, wherein the powder is made of a polylactic acid resin. The open-cell porous body according to claim 1 or 2, wherein the bulk density is 0.01 g / cm ³ or more and 0.2 g / cm ³ or less. 4. The powder according to claim 1, wherein the powder and binder component having a bulk density of 0.001 g / cm ^{3 to} 0.1 g / cm ³ are fused to each other by heating. Open-cell porous body.   The open-cell porous body according to any one of claims 1 to 4, wherein the powder is hydrolyzed. The water absorption material which consists of an open-cell porous body as described in any one of Claims 1-5.