JP3358886B2 - Water-permeable foam molding having voids - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foamed molded article having an open space, having water permeability, and used as a drainage material for civil engineering, construction, horticulture and the like.

[0002]

2. Description of the Related Art A foam molded article having communicating voids is disclosed in Japanese Unexamined Patent Publication No. Hei.
And JP-A-5-177723. Among these, the former molded body is formed by bonding polystyrene foamed resin particles to each other, and the latter molded body has a longest portion having a length of 2c.
A number of non-spherical foam molded chips having a diameter of m or more are fused to each other. Japanese Patent Application Laid-Open No. 3-224727
In the publication, foamed columnar polyolefin-based resin particles having an L / D (L: length of the longest portion, D: cross-sectional length of the maximum body portion) of 2 to 10 are mutually fused in an irregular direction. A foamed molded polyolefin resin body has been proposed. Each of the above-mentioned foamed molded articles has a certain degree of water permeability because of having communicating voids.

[0003] However, in the above-mentioned conventional foam molding, the bonding strength between the foamed particles is insufficient, or it is difficult to balance the porosity and the fusion strength between the foamed particles. However, there is a problem that a porosity exceeding a certain value cannot be obtained, so that a drastic improvement in porosity cannot be expected. That is, since the foamed molded article described above is bonded and integrated with the foamed particles using an adhesive, the bonding strength is weak and brittle. In the foamed molded article described in the second, the longest chip is used. Part length is 2
cm or more, it is difficult to control the porosity of the molded body by controlling the chip filling rate by easily changing the packing density of the chips in the mold, and it is not possible to obtain a uniform porosity. Furthermore, in the last foamed molded article, when trying to obtain a molded article having a sufficient porosity, the fusion strength between the foamed particles becomes weak, and conversely, when trying to increase the fusion strength between the foamed particles, there is a sufficient void. It is difficult to balance both the porosity and the fusion strength such that the porosity cannot be obtained, so that a good molded article having a porosity of a certain value or more cannot be obtained. As described above, the conventional foamed molded article having the interconnected voids does not have a stable and sufficient porosity, and therefore, the control of water permeability to which the influence of the magnitude of the porosity greatly contributes cannot be achieved.

Incidentally, even in the case of a conventional foamed molded article having interconnected voids, a foamed molded article having a large porosity can be obtained if the fusion strength between the foamed particles is ignored. The foam molded article having a sufficient porosity exhibits good water permeability.

[0005] However, when such a foamed molded article having low fusion strength is buried in the ground as an embedding material for a road, for example, it collapses due to a large load from above and digs the road again. It is difficult to collect when performing construction,
The original purpose of reducing the work labor by using the foam molded body instead of embankment etc. can not be achieved, and after all, the fusion strength of the molded body must be emphasized and there is no water permeability and drainage of rainwater etc. A conventional foam molded article having good fusion strength without any voids is used.

Accordingly, the present inventors have previously filed an application (Japanese Patent Application No. 5-309777) relating to a molded product capable of controlling water permeability and having good fusion strength. However, although the above-mentioned molded product exhibits good water permeability, it is necessary to control the water permeability to be small, to obtain uniform water permeability, and to prevent clogging when burying in the ground or the like. Tends to be adjusted to be small. In such a case, particularly in such a case, the surface of the molded article has a strong tendency to repel water immediately after being sprayed with water, and does not readily penetrate the inside of the foamed molded article. In other words, once water has passed through, it shows good water permeability when it passes water continuously, but when water first passes through a dried molded body, it passes until water passes through It takes a long time, and depending on the application and the conditions at the time of use, there are problems such as formation of water pools on the surface of the foamed molded article.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional drawbacks, and it is intended to provide a continuous void having excellent hydrophilicity, quick water wetting, and exhibiting good water permeability from the beginning when water comes into contact with a molded article. It is an object to provide a water-permeable foamed molded article having the same.

[0008]

That is, the present invention provides (1) a foamed molded article having interconnected voids formed by bonding and integrating foamed resin particles, wherein the molded article contains a hydrophilicity imparting agent. Or a water-permeable foamed molded article characterized by being coated, (2) the base resin of the foamed resin particles containing a hydrophilicity-imparting agent to adjust the contact angle to water to less than 96 degrees. A water-permeable foamed molded article containing the hydrophilicity-imparting agent according to the above (1),
(3) The water-permeable foam molded article according to (1) or (2), wherein the hydrophilicity-imparting agent is one or more surfactants selected from polyhydric alcohol fatty acid esters. Is the gist.

[0009]

Embodiments of the present invention will be described below in detail. The water-permeable foamed molded product having interconnected voids of the present invention is a molded product in which a plurality of foamed particles containing or coated with a hydrophilicity-imparting agent are fused and integrated with each other, and a void portion communicated between the foamed particles is provided. have.

In the present invention, the hydrophilicity-imparting agent may be contained in the molded article or may be applied. If applied, the hydrophilicity-imparting agent is washed by passing water through the molded article. There is a problem in terms of sustainability because the surface may be scraped off due to friction of the surface. On the other hand, when the hydrophilicity-imparting agent is contained, even if the hydrophilicity-imparting agent on the surface of the molded body is temporarily washed away or peeled off by water flow or friction, the hydrophilicity-imparting agent is removed from the inside of the molded body. Bleed (leaching)
Even if a hydrophilicity-imparting agent that does not show a bleeding phenomenon is included, it will not be washed away or peeled off by being contained in a molded article.

Further, when a molded article contains a hydrophilicity imparting agent, it is preferable because it has many advantages such as maintaining the hydrophilicity on the cut surface even when cutting is performed at the site where the molded article is used. .

Examples of the hydrophilicity-imparting agent used in the present invention include silicone compounds such as dimethylpolysiloxane, water-soluble polymers such as sulfonated polystyrene, polyoxyethylene and polyvinylpyrrolidone, and ethylene glycol, glycerin and polyethylene glycol. Hydrophilic liquids and surfactants are also included.

Regardless of whether or not the above-mentioned hydrophilicity imparting agent is contained or applied to obtain a molded article, in view of durability and durability, a water-soluble polymer obtained by crosslinking and insolubilizing the polymer is preferable. Surfactants are preferred from the viewpoint of easy handling of the material resin. On the other hand, when a molded body is obtained by adding a hydrophilicity-imparting agent to the base resin, a surfactant is most preferable because of its compatibility with the base resin, durability, bleeding property, and good durability. .

In particular, surfactants are described in detail. Examples include anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants. The following examples are mainly used. Can be That is,
Examples of the anionic surfactants include olefin sulfates, fatty alcohol sulfates such as oleyl alcohol sulfate soda, alkyl sulfates, fatty acid ethyl sulfonates, alkyl sulfonates, and alkyl naphthalene sulfonates. And alkylbenzene sulfonates.

Further, as the cationic surfactant, primary amine salts, tertiary amine salts, quaternary ammonium compounds, pyridine derivatives and the like are used in the present invention.

Other examples of the cationic surfactant include higher alkylamines such as N, N'-bis (hydroxylethyl) -N-alkylamine represented by the following chemical formula (1).

[0017]

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Examples of the nonionic surfactant include sorbitan monofatty acid esters represented by the following chemical formula 2, polyhydric alcohol fatty acid esters represented by the following general formula 3, and the like. The fatty acid pentaerythritol shown, for example, is used in the present invention.

[0019]

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[0020]

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[0021]

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Examples of the polyhydric alcohol fatty acid esters include monoglyceride stearate, monoglyceride oleate, diglyceride stearate, monoglyceride oleate, diglyceride oleate and the like.

Further, other nonionic surfactants include
Carboxyl derivatives, imidazoline derivatives such as hydroxyl ethyl imidazoline sulfate, fatty alcohol ethylene oxide adducts, fatty acid ethylene oxide adducts, fatty amino or fatty acid amide ethylene oxide adducts, alkylphenol ethylene oxide adducts, alkyl naphthol ethylene Oxide adducts, ethylene oxide adducts of polyhydric alcohol fatty acid esters, polyethylene glycol and the like can be mentioned.

In the present invention, the surfactant includes
Among them, it is preferable to use polyhydric alcohol fatty acid esters, and it is particularly preferable that the ester is a partial ester in terms of bleeding speed. When polyhydric alcohol fatty acid esters are used as the surfactant, the foamed particles constituting the molded article do not become insufficiently fused to each other by containing the surfactant. The hydrophilicity can be imparted to the foamed molded article without lowering the fusion strength between the foamed particles in the foamed molded article.

In the present invention, the above-mentioned various surfactants may be used alone or in combination of two or more. Also, higher alcohols and the like can be used in combination.

When a molded product contains a surfactant, a hydrophilic liquid or a silicon compound among the hydrophilicity imparting agents,
The content of the hydrophilicity-imparting agent with respect to the whole foamed molded body is preferably 0.3 to 7% by weight. If the content of the hydrophilicity-imparting agent such as the surfactant is less than 0.3% by weight, the molded body cannot be sufficiently made hydrophilic, and the water permeability of the molded body may not be sufficiently improved. When the content of the hydrophilicity-imparting agent is more than 7% by weight, there is a possibility that a problem may be caused in the fusion property between the foamed particles, such as defective fusion between the foamed particles, and it is uneconomical. In the present invention, the more preferable content of the hydrophilicity-imparting agent is 1.1 to 3% by weight.

When the hydrophilicity-imparting agent is a water-soluble polymer, the content of the hydrophilicity-imparting agent with respect to the whole foamed molded product is preferably 3 to 40% by weight. When the content of the water-soluble polymer is less than 3% by weight, the hydrophilicity cannot be sufficiently increased,
The hydrophilicity of the molded product cannot be sufficiently improved. When the content of the water-soluble polymer exceeds 40% by weight, it is difficult to obtain good expanded particles in the step of obtaining expanded particles from resin particles.

Means for incorporating the hydrophilicity-imparting agent into the foamed molded article include, at the time of producing the base resin particles in the stage prior to producing the foamed particles constituting the foamed molded article, the molten raw material resin and the hydrophilicity-imparting agent. Can be kneaded, but usually it is preferable to prepare a masterbatch of a hydrophilicity-imparting agent in consideration of dispersibility and the like and knead it with the base resin.
As means for forming the base resin mixed with the hydrophilicity-imparting agent into foamed particles, a method in which the base resin mixed with the hydrophilicity-imparting agent is formed into particles, and then the base resin particles are expanded. For example, a method in which foamed particles containing a hydrophilicity-imparting agent are obtained by directly extruding and foaming a base resin mixed with a hydrophilicity-imparting agent and cutting the resin may be used.

On the other hand, when obtaining a molded article coated with a hydrophilicity-imparting agent, the hydrophilicity-imparting agent is preferably 0.01 to 0.5.
A method of applying hydrophilicity to the surface of the foamed molded article by a method of applying the solution to a foamed particle or the like and then molding the particle in a mold can be used.

In the present invention, it is particularly remarkable when the porosity of the foamed molded product is a relatively small one of 5 to 30% or the average of the maximum hole diameter of the void is a relatively small one of 1 to 4 mm. The effect of improving water permeability is obtained. In addition, the water permeability (JIS-A1218 constant water level formula) is 1.0 × 10 ^−3.
-5.0 × 10 ⁻¹ (cm / sec), more preferably 1.0 × 10 ^{−3 to} 1.0 × 10 ⁻¹ (cm / sec). The effect of improving water permeability is obtained.

In the present invention, as means for producing expanded particles, for example, the base resin is melt-kneaded by an extruder, extruded into strands, and then cut into appropriate lengths after cooling, or First, resin particles in the form of pellets are produced by means such as cooling after cutting, and then the resin particles are dispersed in a dispersion medium in the presence of a foaming agent in a closed container, and the temperature is equal to or higher than the softening temperature of the resin particles. The resin particles are impregnated with the blowing agent by heating to a temperature, and then the container is opened once, and the resin particles and the dispersion medium are simultaneously placed in the container while maintaining the pressure in the container at a pressure equal to or higher than the vapor pressure of the blowing agent. Means such as blowing the resin particles under a lower pressure atmosphere (usually under atmospheric pressure) to foam the resin particles are usually employed.

Examples of the base resin used for the expanded particles include polystyrene, poly-α-methylstyrene, styrene-maleic anhydride copolymer, blend or graft polymer of polyphenylene oxide and polystyrene, acrylonitrile-styrene copolymer, acrylonitrile-butadiene- Styrene polymers such as styrene terpolymer, styrene-butadiene copolymer and high impact styrene; polyvinyl chloride, vinyl chloride-
Vinyl chloride polymers such as vinyl acetate copolymers, chlorinated polyvinyl chloride, copolymers of ethylene or propylene and vinyl chloride; polyamide resins, polyester resins, phenol resins, urethane resins, and polyolefin resins.

Examples of the polyolefin resin include polypropylene-based resins such as ethylene-butene random copolymer, ethylene-butene block copolymer, ethylene-propylene block copolymer, ethylene-propylene random copolymer, ethylene-propylene-butene random terpolymer, and homopolypropylene. Resins, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, linear ultra low density polyethylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ethylene-methacrylic acid copolymer Polyethylene resins such as ionomer resins cross-linked with metal ions, polybutene-1, polypentene, ethylene-acrylic acid-maleic anhydride terpolymer Chromatography and the like.

The polyolefin resin may be used in a non-crosslinked state, or may be used after being crosslinked by peroxide or radiation.

Among the above-mentioned base resins, low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, linear ultra-low-density polyethylene, polypropylene, polybutene ,
Preferred are ethylene-propylene copolymer, propylene-butene copolymer, ethylene-butene-propylene terpolymer and the like.

Among the above-mentioned base resins, particularly preferred are ethylene-propylene random copolymer, propylene-butene random copolymer, ethylene-butene random copolymer.
It is a propylene random terpolymer.

In the present invention, the above-mentioned various polymers may be used alone as usual, or may be used in combination of two or more. In addition, a biodegradable plastic such as polycaprolactone, poly-β-hydroxybutyric acid and / or a copolymer thereof, polyvinyl alcohol, and modified starch may be mixed with the above-mentioned base resin. In the case where the biodegradable plastic is mixed with the base resin described above, the two may be mixed before foaming, or the foamed particles obtained by foaming both may be mixed with each other. Alternatively, non-foamed resin particles of a biodegradable plastic may be mixed with foamed particles made of the base resin. Further, it is preferable to add 5 to 40% by weight of a thermoplastic elastomer such as ethylene-propylene rubber to impart flexibility to the base resin.

The base resin particles of the expanded particles are melt-kneaded in an extruder together with, for example, a master batch of an inorganic substance or the like to which the base resin is added, extruded from a die die having a desired cross-sectional shape such as a cylindrical shape, and cooled. After that, it can be obtained by cutting to a predetermined length. In the present invention, as described above, foamed particles can be obtained by conventionally known means.

As the foaming agent used for obtaining the foamed particles, propane, butane, pentane, hexane, cyclobutane, cyclopentane, cyclohexane,
Trichlorofluoromethane, dichlorodifluoromethane, chlorofluoromethane, trifluoromethane, 1,
2,2,2-tetrafluoroethane, 1-chloro-1,
1-difluoroethane, 1,1-difluoroethane, 1
Volatile foaming agents such as -chloro-1,2,2,2-tetrafluoroethane and inorganic gas-based foaming agents such as nitrogen, carbon dioxide, argon, and air, among which the ozone layer is not destroyed. And an inexpensive inorganic gas foaming agent is preferable,
Particularly, nitrogen, air, and carbon dioxide are preferable. The amount of the foaming agent except nitrogen and air is usually 2 to 50 parts by weight per 100 parts by weight of the resin particles. Nitrogen and air are 20-70
It is used by being pressed into a closed container within a pressure range of kgf / cm ² G. The amount of the foaming agent to be used is appropriately selected according to the relationship between the bulk density of the foamed particles to be obtained and the foaming temperature.

In obtaining foamed particles, any dispersion medium for dispersing the resin particles may be used as long as it does not dissolve the resin particles. Examples of such a dispersion medium include:
Water, ethylene glycol, glycerin, methanol, ethanol and the like can be mentioned, but water is usually used.

In the present invention, when the foamed particles are obtained, when the base resin particles are dispersed in a dispersion medium and heated to a set temperature, as long as they do not interfere with the hydrophilicity-imparting action of the hydrophilicity-imparting agent, An anti-fusion agent may be used to prevent fusion between the resin particles. As the anti-fusing agent, any inorganic or organic type can be used as long as it does not dissolve in water or the like and does not melt even by heating, but generally, an inorganic type is preferable. Powders such as kaolin, talc, mica, aluminum oxide, titanium oxide, and aluminum hydroxide are suitable as the inorganic anti-fusion agent. Anionic surfactants such as sodium dodecylbenzenesulfonate and sodium oleate are preferably used as a dispersing aid. As the anti-fusing agent, an average particle diameter of 0.001 to 100 μm, particularly 0.0
It is preferably from 01 to 30 μm. The amount of the anti-fusing agent is usually 0.01 to 100 parts by weight of the resin particles.
10 parts by weight are preferred. The surfactant as a dispersing agent is usually 0.001 to 5 per 100 parts by weight of the resin particles.
It is preferable to add parts by weight. The surfactant as a dispersing agent does not have any adverse effect on the action of the hydrophilicity-imparting agent for imparting hydrophilicity in the present invention.

In the present invention, the foamed particles may be used in a base resin such as black, gray, brown or the like as long as they do not interfere with the hydrophilicity-imparting action of the hydrophilicity-imparting agent. You may color by adding a coloring pigment or dye. If colored foamed particles obtained from a colored base resin are used, a colored foam molded article can be obtained. The color of the coloring pigment or dye is yellow, in addition to those exemplified above,
Red, pink, green, blue and the like can be selected according to the use of the molded article.

When an additive such as a color pigment, a dye or an inorganic substance is added to the base resin, the additive can be kneaded into the base resin as it is. It is preferable to prepare a master batch and knead it with the base resin. The addition amount of the coloring pigment and the dye varies depending on the coloring color, but is usually preferably 0.01 to 15 parts by weight based on 100 parts by weight of the base resin, and talc, calcium carbonate, borax, aluminum hydroxide and the like. When an inorganic substance is added, the amount is preferably 0.001 to 5 parts by weight based on 100 parts by weight of the base resin. By adding the inorganic substance to the base resin in the above amount, an effect of improving the expansion ratio and an effect of adjusting the cell diameter to 50 to 350 μm can be expected.

In the present invention, in addition to the above-mentioned methods for obtaining expanded particles, an extruded foam is obtained by direct extrusion foaming from a die having a desired cross-sectional shape using an extruder.
A method such as obtaining foamed particles by cutting the foam into an appropriate length can be applied.

The shape of the foamed particles used in the present invention may be any shape, such as particles, chips, and pulverized foamed products, but preferably the relationship between the bulk density ρ ₁ of the foamed particles and the true density ρ ₂ is 0. .25ρ ₂ <ρ ₁ <0.55ρ ₂
In the case where the shape of the expanded particles is, for example, a particle shape, specific examples thereof include a cylindrical shape, a polygonal cylindrical shape, and a columnar shape having a cross-shaped cross section which satisfy the above conditions.
As a method for obtaining foamed particles of a desired shape, when adopting a method in which foamed particles are first obtained and then foamed as described above, when the resinous particles are obtained, an extruder is used. The particles can be formed into a desired shape by selecting the shape of the base of the strand outlet, and the resin particles can be foamed into a desired shape by foaming the resin particles. By selecting the die shape of the extruder, the foamed particles can be formed into a desired shape. However, in order to accurately design the expanded particle shape, after obtaining the base resin particles with an extruder,
It is preferable that the resin particles are expanded.

In the present invention, the expansion ratio of the expanded particles can be usually from 3 to 120 times in bulk ratio, but especially from 3 to 30 times because the compression strength of the molded article can be increased. It is preferably used.

In the present invention, when a hydrophilicity-imparting agent is contained in the base resin of the expanded resin particles, the base resin can be selected by utilizing the fact that the contact angle with water is reduced. .

Generally, the higher the content of the hydrophilicity-imparting agent, the smaller the contact angle becomes. Taking advantage of this, the content of the hydrophilicity-imparting agent is adjusted so that the contact angle is preferably less than 96 degrees, and more preferably the contact angle is less than 87 degrees. By selecting and using the base resin adjusted in this way, compared with a foamed molded article without a hydrophilicity-imparting agent added or a foamed molded article made of a base resin having a contact angle of 96 ° or more, the water permeability effect is improved. Significant difference is seen in

For the measurement of the contact angle, a measured value obtained by sandwiching the base resin between aluminum plates corresponding to the symbol A1080P indicated by JIS H4000 and forming a sheet by hot pressing at 200 ° C. is adopted. The substrate resin sheet obtained by the above method was used as a measurement sample, and the following formula was obtained by a droplet method (droplet volume of about 3 mm ³ ) using CA-S Micro 2 manufactured by Kyowa Interface Chemical Co., Ltd. To be measured. θ / 2 = tan ⁻¹ (h / r) θ: contact angle h: water droplet height r: water droplet radius Ultrapure water is used for water used for measurement. In addition, the value of the contact angle was the same for the case where the base resin was formed into a sheet and the case where the foamed molded product was defoamed by hot pressing.

In producing the water-permeable foamed molded article of the present invention, a method is employed in which the above foamed particles are filled in a mold that can be closed but cannot be closed, heated, and the foamed particles are fused together. Is preferred. After the heat fusion molding, the obtained foamed particle molded body is cooled in the mold either by a water-cooling method or by cooling using the heat of vaporization of a heating medium by a vacuum method. May be used, but cooling by a vacuum method is preferable. In the case of water cooling, the voids of the foamed moldings contain water and become heavy, which may hinder the removal from the mold.

The molded article of the water-permeable expanded particles of the present invention makes use of the water permeability of a training course or a horse path for an equestrian club, an underlay material for artificial turf in a roof garden, a drainage facility such as a dark spot, and a drainage promoting material for a golf course. It can be suitably used for applications such as lightweight embankment materials represented by blocks for the EPS method.

In the above case, for example, a molded body of the present invention having a thickness of 30 to 60 mm is placed on the surface of a concrete base having a drain groove formed thereon, and sand or rubber chips having a thickness of 30 to 100 mm are spread over the molded body. Can be used. It is preferable that the molded body is colored gray (substantially the same color as the sand or rubber chips) because the horse is not surprised even when the surface of the molded body is exposed due to the deviation of the surface sand or the like. Coloring is usually performed by kneading, for example, carbon black or the like into the expanded particles at the stage of the base resin particles. In other cases, one is usually placed on a concrete foundation with drainage, if necessary.
A molded body of 0 to 30 mm is laid, and an artificial turf is laid on the molded body for use. Since water is easily discharged from the artificial turf through the molded body, the artificial turf dries quickly. In such a case, it is used in a state in which the periphery of a drain pipe having a hole is covered with a molded body, and sand, gravel, soil, and the like are piled thereon. In such a case, a molded body is laid on the ground, and soil, sand, and turf are sequentially provided thereon. In addition, regarding the embankment material, a styrene foam block having no water permeability is usually used as the embankment material, so the drainage property is poor, and when immersed in a large amount of water, the block may be pushed up and moved by the buoyancy of water accumulated around the block. Because of this, it was necessary to cover with a wedge or a wire mesh. However, the use of the molded article of the present invention promotes drainage and eliminates the above danger.

Next, the present invention will be described in more detail with reference to specific examples. Examples 1 to 5 and Comparative Example 1 Each base resin shown in Table 1 (Examples 1 to 5 and Comparative Example 1), carbon black as a pigment, aluminum hydroxide as an inorganic substance, and a surfactant as a hydrophilicity imparting agent (Comparative Example 1 was not added) was melt-kneaded in an extruder, and then extruded into a strand shape from a die having a die shape substantially similar to the cross-sectional shape perpendicular to the cylinder direction of the cylindrical foam particles, and quenched in water. After cutting into a predetermined length and granulating into cylindrical pellets, 1 kg of these pellets, 40 g of carbon dioxide as a foaming agent, 4 g of kaolin as a dispersant,
A mixture of 0.03 g of sodium dodecylbenzenesulfonate as a surfactant and 3 liters of water as a dispersion medium is stirred in a closed vessel (volume of 5 liters) without raising the temperature to a temperature not lower than the melting end temperature. After raising the temperature to the foaming temperature of 15 ° C. and holding for 15 minutes, a back pressure equal to the equilibrium vapor pressure is applied. One end of the container is released while maintaining the pressure, and the resin particles and water are simultaneously released to release the resin particles in a predetermined manner. , And cylindrical foamed particles having L / D (body length / body diameter) as shown in Table 1 were obtained. The masterbatch was prepared so that the amount of aluminum hydroxide was 0.2 wt%, the amount of carbon black was 0.27 wt%, and the amount of surfactant was such that the amount was as shown in Table 1. Was added.

Each of the above expanded particles is 30 cm long × 30 cm wide.
× Using a 6 cm-thick flat plate mold, a water-permeable foam molded article having a shape according to the above-mentioned mold dimensions was obtained. When molding,
Heating was performed at a steam pressure of 3.2 kgf / cm ² G. In addition, a water-cooled system was adopted for cooling the molded body. The fusing property and hydrophilicity of the obtained molded body were measured, and the values are shown in Table 1. Table 1 also shows the bulk ratio and porosity of the molded body. In addition, among the methods for measuring the bulk density and true density of the expanded particles referred to in the present invention, the methods for measuring the porosity, the fusibility, the hydrophilicity, and the bulk ratio of the molded article shown in Table 1, among the above physical properties The evaluation criteria for those evaluated as 〇 × will be described below.

For the bulk density ρ ₁ (g / cm ³ ) of the foamed particles, a plurality of foamed particles having a known weight M ₁ (g) are placed in a measuring cylinder, and a volume D ₁ ( cm ³ ) divided by the weight M ₁ , that is, M
It is a ₁ / D _1.

The true density ρ ₂ (g / cm ³ ) of the expanded particles is calculated by using a known weight M in a measuring cylinder containing alcohol.
More values lather volume of the particles increase indicated scale of the measuring cylinder when sank D ₂ in (cm ³⁾ obtained by dividing the weight M ₂ with ₂ (g), that is, M ₂ / D _2.

The porosity A (%) of the molded article is determined by calculating the apparent volume B from the external dimensions of the foamed molded article and measuring the increased volume when the foamed particle molded article is calmed in alcohol. A (%) = [(B−
C)] / B] × 100 was obtained from the formula.

The bulk magnification (times) of the molded article is a value obtained by dividing the density (g / cm ³ ) of the base resin by the bulk density ρ ₁ (g / cm ³ ) of the foamed particles used for obtaining the molded article. It is.

The fusibility is 5 cm length × 10 cm width × 5 thickness.
Each of the five test specimens obtained by cutting the foamed molded product so as to have a thickness of 1.0 mm was pulled in the longitudinal direction until each specimen was broken, and the fractured surfaces were observed and evaluated according to the following criteria.・ ・ ・: Many broken parts occurred in the foamed particles of the fractured surface in all the test pieces.・ ・ ・: A broken portion occurred in the foamed particles of the fracture surface in all the test pieces. Δ: In some of the test pieces, a broken portion occurred in the foamed particles having a fractured surface. X: The foamed particles of the fractured surface were cut without breaking in all the test pieces.

As shown in FIG. 1, the hydrophilicity was measured at an angle of 30 degrees, a thickness of 60 mm, a width of 150 mm, and a length of 300 mm.
A graduated container 3 (such as a graduated cylinder) is placed below the inclined surface of the dried molded article 1 and water is supplied from the burette 2 at the top of the surface of the molded article 1 by 25 ml / min. Continue dropping at the dropping speed, and mold 1
The amount of water flowing down the surface of the container 3 and remaining in the container 3 per unit time was measured and evaluated based on the following evaluation criteria. A: The amount of water stored in the container is 0 ml / min. 〇: The amount of water accumulated in the container is more than 0 ml / min and less than 1.5 ml / min. △ ・ ・ ・ 1.5ml /
More than 5 minutes and less than 5 ml / min. ×: The amount of water accumulated in the container is 5 ml / min or more.

[0061]

[Table 1]

[0062]

As described above, since the water-permeable foamed molded article of the present invention contains or is coated with a hydrophilicity-imparting agent, it has good water wettability and can be used immediately after contact with water. Even if there is, water can be allowed to pass therethrough, so that there is an effect that good water permeability can be obtained. In addition, since a molded article containing a hydrophilicity-imparting agent such as a surfactant particularly contains a hydrophilicity-imparting agent in the expanded particles constituting the molded article,
The interior of the molded body is hydrophilic, and the hydrophilicity-imparting agent is not washed away by water or rubs off with other objects, or elutes due to friction, and there is no concern that the hydrophilicity-imparting effect is lost, and the durability is maintained. In addition to being favorable, there is an effect that there is no possibility that the hydrophilicity-imparting agent is eluted in a large amount to cause water pollution or the like.

In the above-mentioned hydrophilicity-imparting agent, when one or two or more selected from polyhydric alcohol fatty acid esters are used as the surfactant, the expanded particles contain the surfactant. By doing so, the fusion between the foamed particles does not become insufficient, and the hydrophilicity can be imparted to the foamed molded article without lowering the fusion strength between the foamed particles in the foamed molded article, and therefore, more favorable. This has the effect that a high water permeability can be obtained.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a test method for evaluating the hydrophilicity of a water-permeable foam molded article of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Water-permeable foam molding 2 Burette 3 Container

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-295652 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 9/228, 9/36

Claims (3)

(57) [Claims] 1. A foamed molded article having interconnected voids formed by bonding and integrating foamed resin particles to each other, wherein the molded article contains or is coated with a hydrophilicity imparting agent. Foam molding. 2. The hydrophilicity-imparting agent according to claim 1, wherein the base resin of the expanded resin particles has a contact angle to water of less than 96 degrees by containing a hydrophilicity-imparting agent. A water-permeable foam molded article containing: 3. The water-permeable foamed molded article according to claim 1, wherein the hydrophilicity-imparting agent is one or more surfactants selected from polyhydric alcohol fatty acid esters.