JP2000290496A - Polyurethane foam having photocatalytic function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyurethane foam resistant to the lowering of strength, etc., of the foam and having excellent physical properties and a photocatalytic function sufficiently exhibiting the photocatalytic function such as antibacterial property. SOLUTION: The objective polyurethane foam having photocatalytic function is produced by treating the surface of anatase titanium oxide surface-treated with a monoalkyltrialkoxy-type silane coupling agent of formula CnH2n+1Si(OR)3 (18>=n>=4; R is CH3 or C2H5) and dispersing the treated titanium oxide in the whole foam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyurethane foam having a photocatalytic function. More specifically, highly safe titanium oxide, which is also approved as a food additive, is dispersed throughout the foam to form a polyurethane foam. The present invention relates to a polyurethane foam provided with a photocatalytic function such as decomposition and removal of harmful chemical substances, decomposition of malodorous substances in the air, and antibacterial and antifungal by photocatalytic action.

[0002]

2. Description of the Related Art Conventionally, polyurethane foams have been used for cleaning foams for kitchen cleaners and the like, cosmetic foams,
It is used as a foam for filters of air conditioners and the like, and a foam for raising seedlings such as Japanese radish, and these foams have recently been required to have antibacterial properties.

[0003] In response to such demands, as a method for imparting antibacterial properties to polyurethane foam, for example, an antibacterial agent is held on the polyurethane foam surface via an adhesive, or an antibacterial agent is dispersed in a solvent. A method has been used in which a polyurethane foam is impregnated in a solvent and then dried to carry an antibacterial agent on the entire foam.

[0004] The antibacterial polyurethane foam produced by such a method is not only extremely difficult to remove the solvent by drying, but also impairs the required texture of the polyurethane foam and causes the antibacterial agent to flow out of the polyurethane foam. There is a problem that the antibacterial property is poor in persistence.

[0005] Antibacterial agents include organic antibacterial agents such as quaternary ammonium salts. These antibacterial agents are poor in persistence and, when used in food containers or food production, are safe. There were many things with sexual problems.

[0006] Compared with these antibacterial agents, silver-based antibacterial agents such as silver-supported zirconium phosphate and silver-supported hydroxyapatite are known, and these are more durable than added organic antibacterial agents. In terms of safety, it is relatively preferable to organic antibacterial agents.

However, when the above silver-based antibacterial agent is added to urethane foam, almost no antibacterial effect can be obtained by a film adhesion method, which is the most common antibacterial test method, for a material having a large porosity such as polyurethane foam. I couldn't.

This is presumably because silver ions necessary for exhibiting antibacterial properties do not elute from the silver-based antibacterial agent embedded in the polyurethane resin. Further, in the case of a silver-based antibacterial agent, it is conceivable that the antibacterial property is impaired due to the action of a catalyst or the like used for a reaction for producing a polyurethane foam.

[0009]

In recent years, the use of titanium oxide in various fields has been attempted since antibacterial properties are obtained by the photocatalytic action of titanium oxide. However, when titanium oxide is dispersed and used in plastic materials such as polyurethane foam, titanium oxide having a large photocatalytic effect has a large oxidizing effect on organic substances, and the resin itself around the titanium oxide is also oxidized and deteriorated. There has been a problem that it is easy to cause a decrease.

The present invention has been made in order to solve the above-mentioned drawbacks, and is a polyurethane having a photocatalytic function capable of sufficiently exhibiting photocatalytic functions such as antibacterial properties, without deteriorating the strength of the foam itself. The purpose is to provide a form.

[0011]

The present invention provides (1) C _n H
Anatase type titanium oxide surface-treated with a monoalkyl trialkoxy type silane coupling agent of _{2n + 1} Si (OR) ₃ (18 ≧ n ≧ 4, R is CH ₃ or C ₂ H ₅ ) (2) a polyurethane foam having a photocatalytic function, wherein the particle size of the anatase type titanium oxide is 25 to 40 nm; and (3) silane. The treatment amount of the coupling agent is 5 to 20 in weight ratio before hydrolysis to anatase type titanium oxide.
% Of the polyurethane foam having a photocatalytic function according to the above (1) or (2).

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The polyurethane foam of the present invention is obtained from a polyol, an organic isocyanate foaming agent, etc., and at least anatase type titanium oxide surface-treated with the above-mentioned specific silane coupling agent is used as a foam. It is dispersed and contained therein.

The polyol, organic isocyanate, foaming agent and the like used in the formation of the polyurethane foam of the present invention may be any of those usually used in the production of polyurethane foam. Also, the amounts of these components can be the same as those used in ordinary production of polyurethane foam. Furthermore, catalysts, foam stabilizers, as long as they are usually used for the production of polyurethane foam,
You may mix | blend other components other than the above, such as a pigment.

According to the present invention, it has a photocatalytic action and is used as an antibacterial agent.
The titanium oxide used is the surface of anatase-type titanium oxide
Is C_n H_{2n + 1}Si (OR)_Three (However, 18 ≧ n ≧ 4, R is
CH _Three Or C_Two H_Five ) Is a monoalkyl trialkoxy
Any material that has been treated with a silane coupling agent
No. The surface of anatase type titanium oxide is silane coupling
Treatment with titanium dioxide, the photocatalytic activity of the titanium oxide
The deterioration of the physical properties of the resin due to
System is controlled so that it does not cause a problem when using
Properties such as antibacterial properties. In addition, the above specific system
Anatase oxidized titan treated with orchid coupling agent
Form polyurethane foam by using
Polyamide with excellent physical properties without adversely affecting the reaction
Urethane foam can be obtained stably.

The particle size (average particle size) of the anatase type titanium oxide is preferably 25 to 40 nm.
The larger the particle size of titanium oxide, the smaller the surface area as particles. Therefore, if the amount of addition is the same, the smaller the particle size, the greater the photocatalytic action. On the other hand, if the amount of titanium oxide added to the polyurethane foam increases, the photocatalytic action increases, but the change in the physical properties of the foam increases. If the particle size of the titanium oxide exceeds 40 nm, it is necessary to increase the addition amount in order to obtain a sufficient photocatalytic action, and the effect on the physical properties of the foam may not be negligible. If the particle size of titanium oxide is less than 25 μm, it is difficult to manufacture, and as will be described later, the surface area becomes very large, the amount of the silane coupling agent required for the surface treatment increases, and the cost increases.

Titanium oxide includes rutile type and brookite type in addition to the anatase type, and the titanium oxide used in the present invention is not limited to 100% anatase type, and the above-mentioned rutile type, brookite type, amorphous layer, etc. May be contained, as long as the component is mainly anatase type.

Since anatase-type titanium oxide is calcined at a low temperature, it has a hydroxyl group on its surface before being treated with a silane coupling agent, and has a property of easily adsorbing atmospheric moisture near the particle surface. The hydroxyl group adsorbing moisture on the surface of the titanium oxide reacts with the isocyanate group of the organic isocyanate at the time of urethane reaction when forming a polyurethane foam, and inhibits a normal reaction between the polyol and the isocyanate.

On the other hand, by treating the anatase type titanium oxide particles 1 with a hydrophobic organoalkoxysilane coupling agent as shown in FIG. Further, it is possible to prevent direct reaction between the adsorbed water and the isocyanate group, thereby stabilizing the physical properties of the polyurethane foam.

The alkoxyl group (R) of the silane coupling agent is a methyl group or an ethyl group. This is because it is necessary to sufficiently remove alcohol and unreacted silane, etc., generated when the titanium oxide surface is treated with a silane coupling agent when forming a polyurethane by adding titanium oxide. Even if alcohol is generated, methyl alcohol, ethyl alcohol, and the like are easily removed by means of vacuum and reduced pressure. In the case of a silane coupling agent having an alkoxyl group other than the above (for example, a long chain having a butyl group or more), it is difficult to remove generated alcohol.

The length of the alkyl group of the silane coupling agent is such that _n of C _n H _{2n + 1} satisfies 18 ≧ n ≧ 4 and n is 4
~ 18 can be used. As the length of the alkyl group increases, the hydrophobicity increases, and the possibility of affecting the polyurethane formation reaction decreases. However, as shown in FIG. 1, when the silane coupling agent is to be arranged on the surface of the titanium oxide particles 1, if the alkyl group (A) becomes large and n becomes 19 or more, it becomes difficult to arrange neatly. Adversely affects the polyurethane formation reaction. On the other hand, if the silane coupling agent has an alkyl group of C18 or less, the arrangement is sufficiently performed and the polyurethane forming reaction can be favorably performed. When the length of the alkyl group of the silane coupling agent is reduced, the hydrophobicity of the titanium oxide is reduced, but the titanium oxide is easily arranged on the surface of the titanium oxide particles.
As shown in (1), an ideal three-dimensional structure of the silane coupling agent is formed on the surface of the titanium oxide, and the surface is completely covered with the silane coupling agent, so that the polyurethane formation reaction is not hindered. However, when n of the alkyl group of the silane coupling agent is 3 or less, the small hydrophobicity cannot be ignored, and the influence on the polyurethane formation reaction may be increased. The length (n) of the alkyl group is preferably 10 ≧ n
≧ 6. More preferably, n = 8, and C ₈ H ₁₇ Si (OCH ₃ ) is used as a specific silane coupling agent.
₃ or C ₈ H ₁₇ Si (OC ₂ H ₅ ) ₃ .

In addition to the alkyl type, there is also a quaternary ammonium salt type silane coupling agent. Urethane foam using titanium oxide treated with this type of silane coupling agent has a sufficient antibacterial effect. Could not be obtained. This is considered to be because the cations and the like in the ammonium ions stop the electron emission due to the ultraviolet irradiation and act as a neutralizing agent, so that the photocatalytic action of titanium oxide is reduced.

The optimal treatment amount of the organoalkoxysilane coupling agent for titanium oxide is such that the particle surface of the anatase type titanium oxide is covered with a monomolecular film (theoretical amount). The minimum coating area of the silane coupling agent is substantially constant without being influenced by the length of the alkyl group or the like, and is approximately 300.
Since it is about 500 m ² / g, the treatment amount can be substantially determined by the particle diameter of the titanium oxide used. Table 1 shows the particle size and surface area of titanium oxide and the situation of titanium oxide when treated with 10% by weight of a silane coupling agent.

As in the case of titanium oxide having a particle size of 50 nm shown in Table 1, when the treatment amount of the silane coupling agent exceeds the above theoretical amount, the excess silane coupling agent is hydrolyzed to form a powder. It may adhere to the surface of titanium oxide to inhibit the polyurethane formation reaction, or may cause deterioration in the physical properties of the generated urethane foam. Table 1
When the treatment amount is smaller than the theoretical amount as in the case of titanium oxide having a particle size of 50 nm shown in (1), a large amount of hydroxyl groups and the like on the titanium oxide surface remains, and the influence on the polyurethane formation reaction increases. Also, as the amount of the silane coupling agent to be treated increases, the raw material cost increases.

For these reasons, it is preferable to use an anatase type titanium oxide having a particle size of 25 nm to 40 nm as a raw material and to use a titanium oxide treated with a silane coupling agent of 5 to 20% by weight based on the titanium oxide. preferable.

[0025]

[Table 1]

As the polyol used in the polyurethane foam of the present invention, one or both of a polyether polyol and a polyester polyol can be used as a mixture. Examples of the polyether polyol include an alkyl oxide adduct of polyhydric alcohol such as ethylene glycol or propylene oxide or ethylene oxide, an alkyl oxide adduct of triethanolamine or the like, and a mixture of propylene oxide and ethylene oxide of the above alcohol or amine. Alkyl oxide adducts, styrene or graft-type polymer polyols such as acrylonitrile, etc., as polyester polyols, aliphatic carboxylic acids such as adipic acid or phthalic acid, aromatic carboxylic acids such as terephthalic acid or a mixture thereof. Ethylene glycol, 3
Methylpentanediol, octanediol, polyester polyol having a hydroxyl group at the end obtained by polymerization from aliphatic glycols such as neopentyl glycol or triols such as glycerin, or caprolactone or β-methylvalerolactone by addition ring-opening polymerization. And the resulting polyester polyols.

The organic isocyanate is an organic compound containing two or more isocyanate groups in the same molecule, and includes aliphatic and aromatic isocyanates, polyisocyanate monomers, mixtures and modified products thereof. It is. Examples of the aliphatic isocyanate include hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and norbonane diisocyanate, and examples of the aromatic isocyanate include tolylene diisocyanate and diphenylmethane diisocyanate.

As the blowing agent, water is mainly used, but if necessary, a low-boiling organic compound such as methylene chloride or a gas such as carbon dioxide can also be used.

Further, in some cases, auxiliary agents such as a flame retardant such as a halogenated phosphoric acid ester, an antioxidant, a plasticizer, a filler and a coloring agent may be blended.

As the catalyst, an amine-based catalyst, a tin-based catalyst, or a combination thereof can be used. Examples of the amine-based catalyst include triethylenediamine, dimethylethanolamine, triethylamine, N, N, N ', N ". , N ''
-Pentamethyldiethylenetriamine, N, N, N ',
There are N'-tetramethylhexaethylenediamine, N-ethylmorpholine, N-methylmorpholine and the like, and as the tin catalyst, dibutyltin dilaurate, dibutyltin diacetate, stannasoctoate, stannasoleate, etc. can be used. .

The antimicrobial polyurethane foam of the present invention can be produced by blending titanium oxide treated with a silane coupling agent with a constituent material of the polyurethane foam and performing a predetermined foam molding reaction. As for the timing of blending the titanium oxide, it may be blended at the same time as a usual auxiliary agent or catalyst, or may be blended at the time of mixing a polyol and an organic isocyanate with a mixing head. In order to uniformly disperse the titanium oxide in the foam, it is desirable that the titanium oxide is previously blended with the polyol or the organic isocyanate. It is desirable that the titanium oxide be blended with the polyol in consideration of the stability of the blended liquid. The addition amount of titanium oxide can be appropriately adjusted depending on the required performance such as antibacterial properties, but is preferably 0.5% by weight or more based on the weight of the polyurethane foam, while the viscosity of the polyol increases as the addition amount of titanium oxide increases. In consideration of the moldability of the polyurethane foam, the content is preferably 20.0% by weight or less.

The titanium oxide used in the present invention has a very large particle surface area as compared with ordinary powder particles, and is difficult to disperse in a polyol or the like. Therefore, the titanium oxide is dispersed using a paint roll or a homogenizer alone or in combination. Preferably.

Experimental Examples 1 to 7 With the following composition, molding was carried out by a conventional method to obtain a polyurethane foam in which anatase type titanium oxide treated with an organoalkoxysilane coupling agent was dispersed. Experimental Example 1 had a particle size of titanium oxide of 20 nm and Experimental Example 2
Is 25 nm, Experimental Example 3 is 30 nm, and Experimental Example 4 is 35 n
m, Experimental Example 5 was 40 nm, and Experimental Example 6 was 45 nm, and the treatment amount of the silane coupling agent was 10% by weight. Octyltrimethoxysilane was used as the silane coupling agent. For comparison, a polyurethane foam without titanium oxide was used as a reference example 1 to obtain a polyurethane foam.
The titanium oxide was used by being dispersed in a polyol in advance.

[Polyurethane foam composition (parts by weight)] Polyol * 1 100 Titanium oxide 1.0 Foam stabilizer 0.8 Water 4.2 Amine catalyst 0.12 Thickener 0.28・ Tin-based catalyst 0.3 ・ Methylene chloride 4.5 ・ TDI-80 * 2 56.67

* 1: Polyether polyol having a molecular weight of 3000 * 2: Tolylene diisocyanate

The obtained polyurethane foam was subjected to a fade meter test and an antibacterial test. The results are shown in Tables 2 and 3. Evaluation of the physical properties of the polyurethane foam was performed according to JIS K6401 and 6402.

The reactivity of Experimental Examples 1 to 6 was determined by T.
(Rising time) was slightly delayed, but almost the same reactivity and physical properties were obtained as compared with the blank of Reference Example 1.

[0038]

[Table 2] [Fedometer test results]

The antibacterial test method is as follows. From each polyurethane foam, respectively to create a test sample of length 50 mm × width 5.0 mm × thickness 1.5 mm, respectively were placed in a sterile plastic Petri dish one by one, then the number of bacteria of E. coli about ¹⁰⁵ The microbial solution adjusted to give the number of cells / ml was added to the specimen in each petri dish at 0.
5 ml of the mixture was dropped, and the Petri dish was covered with a polyethylene film to block the outside air, thereby preventing the bacterial solution on the sample sample from drying and the invasion of bacteria from the outside. Ultraviolet irradiation of the specimen was performed by irradiating a petri dish with 20 W of black light at a distance of 40 cm from the specimen and storing the specimen at room temperature. Four hours after the light irradiation, the bacterial solution was washed out from the sample in each petri dish, transferred to a culture medium, and the number of viable bacteria was measured to obtain the number of bacteria in the sample. In addition, the viable cell count was measured in the same manner immediately after the dropping of the bacterial solution, and on the product stored in a dark room without irradiating light. For each specimen, the number of viable bacteria was measured for three specimens under the same conditions, and the average value was calculated. The results are shown in Table 3. In addition, a numerical value of 10 or less indicates that no viable bacteria were detected.

[0040]

[Table 3] [Results of antibacterial test of polyurethane foam]

In general, regarding the antibacterial effect, if the number of detected viable bacteria differs from blank by two digits or more,
It is said to have antibacterial effects. From the results in Table 3,
The test results of Experimental Examples 1 to 5 irradiated with ultraviolet light were all 10
The antibacterial properties are very good in the following, and Experimental Example 6 is Reference Example 1
The antibacterial property was better than that, and the effect was confirmed.

The particle size of titanium oxide is 0.2 to 0.3 μm.
Was used to produce a polyurethane foam in the same manner as in Experimental Examples 1 to 6, and evaluated for antibacterial properties. As a result, favorable antibacterial properties were not obtained.

The amount of ultraviolet light in summer is 2 to 4 mW / c.
m ² , and the irradiation dose in this test was 1 compared to summer.
Although the amount is ３ to １ ／, the effect can be obtained by irradiation of such a small amount of ultraviolet rays. (Heisei 1
The light amount measured outdoors at 12:30 am on December 20, 2000 was about 1000 μW / cm ² . In addition, it was about 70 to 140 μW / cm ² indoors through the window glass. )

Experimental Examples 7 to 10, Reference Example 2 Titanium oxide having a particle size of 30 nm was converted to an alkyl group having a length of C ₄
(Experimental Example 7), C ₆ (Experimental Example 8), C ₈ (Experimental Example 9),
Polyurethane was produced in the same manner as in Experimental Examples 1 to 6, using titanium oxide treated with a C ₁₀ (Experimental Example 10) and C ₂₀ (Reference Example 2) monoalkyltrimethoxysilane coupling agent (processing amount: 10% by weight). A foam was formed, and the foaming state of the polyurethane foam was observed. As a result, in Reference Example 2 to C ₂₀ was poor foaming state. The experimental examples 9 to C ₈ foamed state was the best.

[0045]

As described above, according to the present invention, C _n H
Anatase type titanium oxide surface-treated with a monoalkyl trialkoxy type silane coupling agent of _{2n + 1} Si (OR) ₃ (18 ≧ n ≧ 4, R is CH ₃ or C ₂ H ₅ ) By adopting a structure in which the polyurethane foam is dispersed and contained, a polyurethane foam having good physical properties and excellent photocatalytic functions such as antibacterial properties can be obtained. Since the surface of titanium oxide used as a photocatalyst has been treated with a silane coupling agent, a decrease in the physical properties of the resin is suppressed, and the ordinary use of the polyurethane foam does not affect the physical properties.

Further, by using anatase type titanium oxide treated with the above-mentioned specific silane coupling agent, it is possible to stably produce a polyurethane foam having good physical properties without affecting the polyurethane formation reaction. It is possible.

The polyurethane foam of the present invention can provide a hydroponic vegetable which maintains its antibacterial properties even when washed with water and does not have to worry about adhesion of Escherichia coli and the like when used as a nursery bed for radish and the like. Further, when used as a sponge for washing dishes at home, even if the sponge is used continuously, a special state of sterilization and disinfection is not required, and a clean state can be maintained only by light irradiation.

The photocatalytic action of titanium oxide has not only antibacterial properties but also effects such as air purification and deodorization. The polyurethane foam of the present invention can be used for an air purification device for a filter of an air conditioner.

[Brief description of the drawings]

FIG. 1 is a view for explaining a state in which the surface of titanium oxide particles has been treated with a silane coupling agent.

[Explanation of symbols]

 1 Anatase type titanium oxide particles

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI theme coat テ ー マ (reference) C09C 3/12 C09C 3/12 F term (reference) 4G069 AA15 BA04A BA04B BA48A CA17 EB18X EB18Y EC22X EC22Y EE01 4J002 CK021 DE136 EX036 FA091 FB096 FD206 GQ00 4J037 AA22 CB23 CB26 CC26 DD05 EE02 EE08 EE28 FF26 FF30

Claims (3)

[Claims] 1. A _{C n H 2n + 1 Si (} OR) 3 ( where 18 ≧
Photocatalytic function wherein anatase type titanium oxide surface-treated with a monoalkyl trialkoxy type silane coupling agent wherein n ≧ 4 and R is CH ₃ or C ₂ H ₅ ) is dispersed and contained throughout. Polyurethane foam having: 2. The particle size of the anatase type titanium oxide is 25 to 25.
The polyurethane foam having a photocatalytic function according to claim 1, which has a thickness of 40 nm. 3. The treatment amount of the silane coupling agent is 5 to 5% by weight of the anatase type titanium oxide before hydrolysis.
The polyurethane foam having a photocatalytic function according to claim 1 or 2, which is 20%.