JP2017057327A - Polyurethane foam for water treatment carrier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyurethane foam for water treatment carrier having high submergence without specific post-processing on a carrier itself.SOLUTION: There is provided a polyurethane foam for water treatment carrier consisting of a polyol component, an isocyanate component, a catalyst, a foaming agent and a foam stabilizer, wherein the polyol component contains polyether polyol (I) having a number average molecular weight of 3000 to 5000, an average functional group number of 2 to 4 and an ethylene oxide percentage content of 60% or more, and polyether polyol (II) having a number average molecular weight of 2000 to 4000, an average functional group number of 2 to 4 and an ethylene oxide percentage content of 20% or less, ratio of the polyether polyol (I) and the polyether polyol (II) is, by weight ratio, polyether polyol (I)/polyether polyol (II)=60 to 90%/40 to 10%, the isocyanate component is diphenylmethane diisocyanate, and submergence is 600 seconds or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polyurethane foam used for a water treatment carrier used by being immersed in waste water.

  As a wastewater treatment, there is a biological treatment method using microorganisms, which involves immersing a carrier supporting microorganisms in a treatment tank in which wastewater discharged from general households, factory facilities, industrial facilities, etc. is stored. It is characterized by treating the wastewater using its function.

  As the biological treatment method, a water treatment carrier made of a resin foam is placed in and disposed in an aeration tank provided in a septic tank or the like (hereinafter referred to as a treatment tank), and microorganisms are propagated inside the resin foam. This is a treatment method in which organic matter in wastewater is decomposed by microorganisms supported (hereinafter referred to as fixing) and held by the resin foam.

  In the treatment method, the reason why the resin foam is used is that the surface area is large and microorganisms can easily form a biofilm on the surface of the cell of the resin foam. . Examples of the resin foam include polyolefin resin foam and polyurethane resin foam.

  However, the polyurethane foam, which is the resin foam, generally has low hydrophilicity and is not easily adapted to water, and air is held inside by foamed cells (cells). For this reason, even if a 10-mm dice carrier made of a resin foam is put into the treatment tank, it is difficult to sink below the surface of the water, and the specific gravity and the like are low, so that it tends to float on the surface of the water. As a result, it took a long time for the waste water to be immersed in the carrier and swirled through the waste water by stirring, and depending on the thing, it continued to float on the water surface for several days. In the wastewater treatment by the biological treatment method, if the carrier is not immersed in the wastewater, microorganisms do not settle on the carrier and stable wastewater treatment performance cannot be obtained. Accordingly, there has been a demand for further shortening the time (hereinafter referred to as submergence) required from the time when the carrier is put into the waste water until it is immersed.

  In order to solve the above problems, the foam cell is roughened, the cell membrane is removed (film removal treatment), and the drainage into the foam is improved (Patent Document 1), inorganic It has been performed to adjust the apparent specific gravity by applying an apparent specific gravity improver such as fiber, inorganic fine particle, metal fiber, metal fine particle or synthetic resin, or by adhering and curing an isocyanate-terminated polyurethane prepolymer. (Patent Document 2, Patent Document 3).

JP 2004-250593 A JP 2002-292385 A JP 2010-119979 A

  As in Patent Document 1, by removing the film, the water permeability of the foam is improved, and it is easy to physically pass water. However, the time required for immersion is shortened due to the hydrophobicity of the foam itself. It was not sufficient, and there was also a problem that it became difficult to support microorganisms as a result of removing the cell membrane. On the other hand, in Patent Document 2 and Patent Document 3 in which the apparent specific gravity is improved, the penetration property of the drainage of the portion is lowered by applying a resin or the like on one surface of the carrier, and the dipping time is not sufficiently shortened. In addition to the above, when actually used, that is, when being stirred in the treatment tank, there is a problem that the material attached to improve the specific gravity falls off, causing the carrier itself to pollute the water. there were.

  An object of the present invention is to solve the above-mentioned problems and to provide a polyurethane foam for a water treatment carrier having high water settling without post-treatment of the carrier itself.

In order to solve the above problems, the polyurethane foam for a water treatment carrier of the present invention comprises (1) a polyol component, an isocyanate component, a catalyst, a foaming agent, and a foam stabilizer, and the polyol component has a number average molecular weight of 3000. To 5000, polyether polyol (I) having an average number of functional groups of 2 to 4, ethylene oxide content of 60% or more, number average molecular weight of 2000 to 4000, average number of functional groups of 2 to 4, ethylene oxide content of The polyether polyol (II) is 20% or less, and the ratio of the polyether polyol (I) to the polyether polyol (II) is, by weight ratio, polyether polyol (I) / polyether polyol (II ) = 60-90% / 40-10%, and the isocyanate component is diphenylmethane dii A cyanate, characterized in that submerged resistance is less than 600 seconds.
Furthermore, (2) It is more preferable that the number of cells is 25 to 45 cells / 25 mm and the air flow rate is 3 ml / cm ² / s or more.

  The polyurethane foam for a water treatment carrier of the present invention has very high water settling without subjecting the foam to a special post-treatment. Therefore, if the polyurethane foam for a water treatment carrier of the present invention is used, the water treatment carrier can be quickly immersed in the treatment tank and then quickly transferred to the microorganism fixing stage. For this reason, compared with the conventional water treatment support | carrier, the time required to exhibit the stable water treatment performance can be shortened greatly.

It is a reference figure for explaining submergence.

  Hereinafter, the polyurethane foam for a water treatment carrier of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a reference diagram of the submersion test. The “water subsidence” in the present invention refers to the property that the water treatment carrier sinks into water after the water treatment carrier is put on the waste water.

  The polyurethane foam for a water treatment carrier of the present invention is obtained by mixing and foaming raw materials comprising a polyol component, an isocyanate component, a foaming agent, a foam stabilizer, and a catalyst, and has a water settling of 600 seconds or less.

  As said polyol component, at least 2 sort (s) of polyether polyol (I) and polyether polyol (II) is included.

  Polyether polyol (I) has a number average molecular weight of 3000 to 5000, an average number of functional groups of 2 to 4, and an ethylene oxide content of 60% or more. The EO content is preferably 70% or more.

The polyether polyol (II) has a number average molecular weight of 2000 to 4000, an average number of functional groups of 2 to 4, and an ethylene oxide content of 20% or less.

The blending ratio of the polyether polyol (I) and the polyether polyol (II) is such that when the total amount of the polyether polyol (I) and the polyether polyol (II) is 100% by weight, the polyether polyol (I) / Polyether polyol (II) is 60 to 90% / 40 to 10%.
The EO content in the polyol component is more preferably 45 to 68%. If the EO content is too high, collapse tends to occur, while if it is too low, shrinkage tends to occur when foaming.

  In addition, as said polyol component, if it is a grade which does not impair the effect of this invention, you may use together the well-known polyol generally used for the flexible polyurethane foam. For example, low molecular weight polyols that can be used as a crosslinking agent are exemplified.

Diphenylmethane diisocyanate (MDI) is used as the isocyanate component.
Moreover, it is preferable to set it as the weight ratio of 90-120 by an isocyanate index as a compounding ratio of a polyol component and an isocyanate component. By setting the isocyanate index in the numerical range, it is easy to obtain predetermined water settling.

In addition, as long as it is a grade which does not impair the effect of this invention, you may use together the well-known isocyanate currently used for the flexible polyurethane foam as said isocyanate component.
Examples of known isocyanates include aromatic polyisocyanates such as tolylene diisocyanate (TDI) 1,5-naphthalene diisocyanate and paraphenylene diisocyanate, and aliphatic polyisocyanates such as hexamethylene diisocyanate, hydrogenated MDI and isophorone diisocyanate. It can also be used. In addition to these, a prepolymer type polyisocyanate can also be used.

  As a foaming agent, the well-known thing used for manufacture of a polyurethane foam can be used. For example, water, acid amides, nitroalkanes, etc., which decomposes by heat, such as trichlorofluoromethane and chlorodifluoromethane as low-boiling inert solvents, methylene chloride, water, acid amide, nitroalkane etc. Examples of those that generate water include sodium bicarbonate and ammonium carbonate. These foaming agents may be used alone or in combination of two or more. Preferably, water and methylene chloride are used in combination. Use of water and methylene chloride is preferable because the polyurethane foam can be foamed well.

  When water is used as the foaming agent, it is preferably contained in an amount of 1.5 to 5% by weight based on 100% by weight of the polyol component. Further, when methylene chloride is used in combination, it is preferably contained at 11% by weight or less. By using methylene chloride in the above range, a high air flow rate and water settling can be easily obtained.

  As a foam stabilizer, a well-known thing used for manufacture of a flexible polyurethane foam can be used. For example, silicone type foam stabilizers such as various siloxane-polyether block copolymers can be used.

  The blending amount of the foam stabilizer is preferably 0.5 to 3.0% by weight with respect to 100% by weight of the polyol component. When the amount is too small, it is difficult to obtain a foam regulating effect, while when it is too large, there is a possibility that the air flow rate and the compression residual strain are deteriorated.

  As a catalyst, the well-known thing used for manufacture of a polyurethane foam can be used. For example, amine-based catalysts such as tertiary amine compounds such as triethylamine, triethylenediamine, bis (2-dimethylaminoethyl) ether, N-methylmorpholine, dimethylaminomethylphenol, and imidazole can be used. In addition, a metal catalyst such as an organic tin compound such as stannous octoate or an organic nickel compound such as nickel acetylacetonate may be used. These catalysts may be used alone or in combination of two or more. In addition, the compounding quantity of a catalyst can be 0.1-1.5 weight%, when the said polyol component is 100 weight%.

  If necessary, other additives can be used in combination as long as the effects of the present invention are not impaired. For example, an antioxidant, a UV absorber, a colorant, and a diluent for reducing the viscosity of the urethane foam raw material to facilitate stirring and mixing.

  The polyurethane foam for a water treatment carrier of the present invention has a water settling of 600 seconds or less. For this reason, when thrown into the treatment tank, it is immediately immersed in the waste water, and the waste water treatment efficiency is improved.

The polyurethane foam for a water treatment carrier preferably has an air permeability of 3 ml / cm ² / s or more without being subjected to film removal treatment, more preferably 90 ml / cm ² / s or more, and 220 ml / cm ² / s. More preferably, it is s or more. If the aeration rate is 3 ml / cm ² / s or more, the water settling can be satisfactorily 600 seconds or less, and if it is 90 ml / cm ² / s or more, the water settling is less than 120 seconds, If it is 220 ml / cm ² / s or more, the water settling is less than 60 seconds, so that the time required for the immersion of the water treatment carrier can be greatly reduced. Incidentally, when the aeration amount can exceed 330ml / ^cm 2 / s, the hardness and mechanical strength of the upper limit of the air permeability of at most 330ml / ^cm 2 / s for fear is to decrease preferred.

  Furthermore, the polyurethane foam for a water treatment carrier preferably has 25 to 45 cells / 25 mm. It is preferable for the number of cells to be in the above numerical range because of excellent mechanical strength and wear resistance.

  The polyurethane foam for a water treatment carrier of the present invention is produced by a conventionally known method. For example, it can be obtained by a method in which a polyol component is mixed with a component excluding an isocyanate component such as a foaming agent, a foam stabilizer, a catalyst, and other auxiliary agents, and then mixed and foamed with the isocyanate component.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to a following example.
[sample]
<Polyol component>
Polyol A: polyether polyol (Accor EP-505S, manufactured by Mitsui Chemicals, Inc.) having a number average molecular weight of 3360, a functional group number of 3, and an EO content of 75%
Polyol B: Polyether polyol having a number average molecular weight of 3,000, a functional group number of 3, and an EO content of 0% (Asahi Glass Co., Ltd., EXCENOL3030)
<Isocyanate component>
Isocyanate A: Polymeric MDI having an NCO content of 31.5% (manufactured by Tosoh Corporation, MR-200)
Isocyanate B: TDI with an NCO content of 42.8% (Mitsui Chemicals Cosmonate T-80)
<Foaming agent>
Foaming agent A: water (ion exchange water)
Foaming agent B: methylene chloride <foam stabilizer>
Foam stabilizer: Silicone surfactant (manufactured by Dow Corning Toray, SH-192)
<Catalyst>
Catalyst A: tertiary amine catalyst, triethylenediamine 33% dipropylene glycol solution (TODA Corporation, TEDA-L33)
Catalyst B: Stanas octoate (Nitto Chemical Co., Ltd., Neostan U-28)

  At the blending ratios shown in Table 1 and Table 2, various foaming agents, foam stabilizers and catalysts were mixed with the polyol component, then mixed with the isocyanate component, and foamed and cured to produce a polyurethane foam. Various evaluations were performed on the polyurethane foam by the following methods.

[density]
It measured based on JISK7222A method.
[Number of cells]
Measured based on JIS K 6400 (Annex).
[Fragile airflow]
It measured based on JISK6400-7B method.
[Submergence]
The obtained polyurethane foam is cut into a cube of 10 mm × 10 mm × 10 mm, and from the stage of standing the carrier on the water surface (FIG. 1- (a)), water soaks from the lower surface of the carrier, and the carrier gradually The time required to completely submerge in water (FIG. 1- (c)) through the stage of sinking into water (FIG. 1- (b)) was completely measured up to the upper surface of the carrier.

<Examples 1 to 10>
The polyurethane foam for a water treatment carrier of the present invention has a very high performance such that the water settling is 600 S or less. Therefore, it can be immersed in a short time when thrown into the waste water.

<Comparative Example 1 and Comparative Example 2>
Comparative Example 1 is a polyol component having an EO content of 41%, comprising 55.0% by weight of polyol A (polyether polyol (I)) and 45.0% by weight of polyol B (polyether polyol (II)). used. On the other hand, in Comparative Example 2, polyol A (polyether polyol (I)) was blended at 95.0 wt% and polyol B (polyether polyol (II)) at 5.0 wt%, and the EO content was 71%. The polyol component was used.
As a result, Comparative Example 1 had severe shrinkage after foaming, and Comparative Example 2 had collapsed, and neither of them had a good foam.
<Comparative Example 3>
In Comparative Example 3, TDI was used as the isocyanate component.
As a result, the water settling was as long as 690 seconds.
<Reference Example 1>
As Reference Example 1, a conventionally used polyurethane foam for water treatment carrier was examined.
As a result, it was confirmed that the submergence study results required several days, and the immersion time was long and the practicality was low.
<Reference Example 2>
As Reference Example 2, a non-film polyurethane foam obtained by subjecting the polyurethane foam for a water treatment carrier of Reference Example 1 to film removal treatment in order to enhance water immersion was examined.
As a result, since the film removal treatment has been performed, the water permeability of the foam itself has been confirmed, but as a result, the time required for water subsidence required several days.

  As confirmed in the above examples, the polyurethane foam for water treatment carrier in the present invention has very high water subsidence compared with the conventional polyurethane foam for water treatment carrier and is put into the treatment tank. It is possible to greatly reduce the time required for immersion from the beginning, leading to the efficiency of water treatment.

1: Water treatment carrier 2: Drainage 3: Immersion area in water treatment carrier

Claims (2)

Polyurethane foam for water treatment carrier consisting of polyol component, isocyanate component, catalyst, foaming agent, foam stabilizer,
The polyol component has a polyether polyol (I) having a number average molecular weight of 3000 to 5000, an average functional group number of 2 to 4, an ethylene oxide content of 60% or more, a number average molecular weight of 2000 to 4000, and an average functional group number. 2 to 4 and a polyether polyol (II) having an ethylene oxide content of 20% or less,
The ratio of the polyether polyol (I) and the polyether polyol (II) is, by weight ratio, polyether polyol (I) / polyether polyol (II) = 60 to 90% / 40 to 10%,
The isocyanate component is diphenylmethane diisocyanate;
A polyurethane foam for a water treatment carrier, wherein the water settling is 600 seconds or less. ^{2. The} polyurethane foam for water treatment carrier according to claim 1, wherein the number of cells is 25 to 45 cells / 25 mm, and the air flow rate is 3 ml / cm ² / s or more.

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