JP2003119242A - Method for producing polyurethane foam and heat insulating box - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a high quality polyurethane foam which excels in heat insulating performance, mechanical strengths and the like, and a heat insulating box using this polyurethane foam. SOLUTION: An inorganic lamellar substance is uniformly dispersed in the resin of a polyurethane foam by previously dispersing the inorganic lamellar substance in a polyisocyanate in crystal layer units.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyurethane foam having excellent mechanical strength, and an insulating box body in which an outer box and an inner box are filled with the polyurethane foam obtained by this method.

[0002]

2. Description of the Related Art Foamed heat insulating materials are widely used in equipment such as refrigerators, freezers, refrigerating / freezing cases, heat-retaining rooms, etc. that keep the inside temperature at a predetermined temperature against changes in ambient temperature. Among them, polyurethane foam is often used because of its excellent heat insulating property and productivity.

Polyurethane foam is required to have a good heat insulating property from the viewpoint of energy saving, but in the equipment such as the refrigerator, the freezer and the heat retaining room, the polyurethane foam not only functions as a heat insulating material but also has a structure. As a result, the function of supporting the main body of the equipment is also required, and low density and high strength polyurethane foam is being actively developed.

As a method of increasing the strength of the polyurethane foam, it is possible to increase the strength of the polyurethane resin which is the matrix of the polyurethane foam.

For example, in Japanese Unexamined Patent Publication No. 10-168305, an inorganic layered substance is organized by an organic onium ion and then swollen with an oligomer containing a functional group which reacts as a polyol component of polyurethane, and then,
An oligomer containing the inorganic layered material is mixed with an isocyanate compound to cause a polyurethane reaction between the functional group of the oligomer and the isocyanate compound,
A method for producing a polyurethane rubber composite material having excellent tensile strength is disclosed.

However, in this manufacturing method, the inorganic layered material organically modified with an organic onium ion is added to the component of the polyurethane rubber which is hydrogen bonded to the inorganic layered material, that is, the polyol. However, in the formation of polyurethane foam, the reaction of the polyol, which is the main component forming the polyurethane resin, and the isocyanate compound is fast, so it is necessary to uniformly mix the polyol and the isocyanate compound in a short time. However, since the polyol has a higher viscosity than the isocyanate compound and hydrogen bonds with the inorganic layered substance, the viscosity of the polyol becomes extremely large when the inorganic layered substance is added to the polyol. That is,
Since the viscosity difference between the polyol and the isocyanate compound becomes large, for example, when foam molding is performed using a high-pressure foaming machine that is widely used in the production of thermosetting rigid polyurethane foam, the mixing of the polyol and the isocyanate compound is poor, and the matrix resin However, there is a problem in that the polyurethane resin, which is the above item, is not cured sufficiently and the characteristics of the polyurethane foam cannot be exhibited. Further, there is a problem that the inorganic layered substance cannot be finely dispersed in the polyurethane resin of the matrix resin, and the effect of strengthening the strength of the polyurethane foam by the inorganic layered substance cannot be exhibited.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and even in the foam molding of polyurethane foam having a short curing time and high productivity, the matrix resin is used. It is intended to provide a method for forming a polyurethane foam excellent in mechanical strength by finely dispersing an inorganic layered substance in crystal layer units.

[0008]

A first method for producing a polyurethane foam according to the present invention comprises mixing a polyisocyanate compound in which an inorganic layered material is dispersed with a polyol containing a foam stabilizer, a catalyst and a foaming agent. To foam.

A second method for producing a polyurethane foam according to the present invention is the same as the first method for producing a polyurethane foam, wherein the inorganic layered substance is montmorillonite, saponite, hectorite, beidellite, stevensite, nontronite, vermiculite. , Halloysite, magadiite, kanemite, and mica.

A third method for producing a polyurethane foam according to the present invention is the same as the method for producing a polyurethane foam according to the first or second aspect, wherein the inorganic layered substance has an organic onium ion having a substituent capable of reacting with an isocyanate compound in the molecule. It is to be modified beforehand with a compound.

The first heat insulating box body according to the present invention is foamed by the manufacturing method according to any one of claims 1 to 3 in an outer box, an inner box, and a gap between the outer box and the inner box. , Filled polyurethane foam.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1. The method for manufacturing the polyurethane foam in the first embodiment is performed, for example, in the following procedure. First, an organic onium ion compound having a substituent capable of reacting with an isocyanate compound is dissolved in acidic water, preferably acidic warm water. The inorganic layered substance is added to water in which the organic onium ion compound is dissolved and sufficiently stirred to obtain a precipitate of the inorganic layered substance cation-exchanged with the organic onium ion. The precipitate is thoroughly washed with water and then dried to obtain an inorganic layered substance cation-exchanged with an organic onium ion compound (hereinafter referred to as an onium-modified inorganic layered substance).

Next, the above-mentioned onium-modified inorganic layered material is added to the isocyanate compound and the mixture is sufficiently stirred to obtain an isocyanate mixture in which the onium-modified inorganic layered material is homogeneously dispersed. Next, a foam stabilizer, a catalyst, and a foaming agent are added to the polyol to obtain a well-mixed polyol mixture. If necessary, auxiliary materials such as a chain extender, a cross-linking agent, a flame retardant, an antioxidant, an ultraviolet absorber, an anti-hydrolysis agent, and a colorant may be added. The isocyanate mixture containing the onium-modified inorganic layered material thus obtained and the polyol mixture were stirred and mixed in a high-pressure foaming machine under the conventional polyurethane foam molding conditions, that is, for about 0.5 to 5 minutes. The reaction is carried out in a short time to foam and form a polyurethane foam containing the onium-modified inorganic layered material.

In the present embodiment, the isocyanate compound is a compound having two or more isocyanate groups in one molecule. Such compounds include:
For example, diphenylmethane diisocyanate (hereinafter MD
I), polymeric MDI, toluene diisocyanate (hereinafter referred to as TDI), hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, phenylene diisocyanate, dimethyldiphenyl diisocyanate, tetramethylene diisocyanate,
Examples thereof include isophorone diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate. In the present embodiment, these compounds may be used alone or in combination of two or more kinds.

As the isocyanate compound, for example, an isocyanate prepolymer prepared by reacting a compound having a plurality of active hydrogens in one molecule with an isocyanate compound having an equivalent amount of isocyanate groups larger than the equivalent amount of the active hydrogens of the compound. Alternatively, a polyisocyanate such as an oligomer obtained by reacting the polyisocyanates with each other for several molecules can be used.

In the present invention, examples of the polyol include active hydrogen compounds such as glycerin, trimethylolpropane, pentaerythritol, ethylenediamine, triethanolamine, triethylenediamine, tolylenediamine, diphenylmethanediamine, methylglycoside, sorbitol and sucrose. A polyether polyol compound obtained by adding one molecule or more of an epoxide group such as ethylene oxide or propylene oxide, to a polyester polyol compound in which a polyfunctional hydroxy compound is polycondensed with a polyfunctional carboxylic acid compound such as phthalic acid, or these And a mixture of the above.

In the present invention, the inorganic layered substance is an inorganic compound having a layer structure in which layers formed by covalent bonds or strong bonds having strong covalent properties are stacked by weak bonds. Examples of such compounds include graphite, layered boron nitride, arsenic,
Examples include molybdenum sulfide, mica, and clay minerals. In particular, mica and clay minerals such as montmorillonite, saponite, hectorite, beidellite, stevensite, nontronite, vermiculite, halloysite, magadiite, kanemite and mica are dispersible in polyurethane foam and are available from the viewpoint of availability. Is preferred.

The amount of these inorganic layered substances added to the isocyanate compound is 3 to 30 parts by weight, particularly 3 to 10 parts by weight, relative to 150 parts by weight of the isocyanate compound. If the amount added is less than 3 parts by weight, the effect of increasing the strength of the polyurethane foam by the addition of the inorganic layered material is not remarkable, and if the amount added exceeds 30 parts by weight, the viscosity of the isocyanate mixture containing the inorganic layered material increases. ,
Mixing with the polyol mixture during foam molding becomes insufficient, and the strength and heat insulating properties of the polyurethane foam decrease. Further, if the amount of the inorganic layered substance added exceeds 10 parts by weight, the specific gravity of the polyurethane foam increases.

In the present embodiment, examples of the compound used for previously modifying the inorganic layered material with the organic onium ion include ammonium salts, phosphonium salts, sulfonium salts, and the like. From the viewpoint of availability, the ammonium salt is particularly preferable. . However, it is not limited to these salts.

Examples of the substituent contained in the organic onium ion compound and capable of reacting with the isocyanate compound include a substituent having an active hydrogen such as a hydroxyl group, an amino group, a carboxyl group and a hydrosulfur group, a glycidyl group and an isocyanate group. Is raised.

In the present embodiment, since the inorganic layered material is onium-modified, the inorganic layered material is uniformly dispersed in the isocyanate compound in crystal layer units. Therefore, even if the polyureta foam is foam-molded by mixing the isocyanate compound to which the inorganic layered substance is added and the polyol and curing the gel time for a short time of 5 minutes or less, the crystalline layer of the inorganic layered substance is previously formed in the isocyanate compound. Since it is sufficiently exfoliated, it is possible to easily obtain a polyurethane foam in which the inorganic layered substance is uniformly dispersed in crystal layer units. Furthermore, since the inorganic layered material is dispersed in an isocyanate compound having a viscosity lower than that of the polyol, the difference in viscosity between the isocyanate mixture and the polyol mixture is not so large, and it is possible to uniformly mix both components with an existing foam molding machine. it can.

Further, in the present embodiment, since the inorganic layered material is modified with the organic onium ion compound having a substituent capable of reacting with the isocyanate compound in the molecule, when the inorganic layered material is dispersed in the isocyanate compound,
The organic onium ion and the isocyanate compound react between the layers of the inorganic layered material, the layers of the inorganic layered material are further expanded, and the dispersion of the inorganic layered material in crystal layer units becomes more uniform. In addition, since the organic onium ion and the isocyanate compound form a covalent bond, the inorganic layered substance and the isocyanate compound more strongly influence each other via the organic onium ion, and a polyurethane foam machine obtained by using this isocyanate compound Strength is dramatically improved.

The polyurethane foam of this embodiment also has
It can be used as a heat insulating material having a required shape and excellent in heat insulating property, strength and dimensional stability by processing into various shapes after foam molding. Further, when the polyurethane foam is foamed, it can be used as a heat insulating material surrounding the periphery of a member having a complicated shape by appropriately adopting a method such as an injection method, a casting method or a spraying method. By filling this polyurethane foam in the space between the outer box and the inner box such as a box body, it is possible to obtain a heat-insulating box body that is lightweight, has high strength, is excellent in heat retention performance, and has a large effective volume.

[0024]

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

Example 1. An onium-modified inorganic layered material is prepared as follows. 100 g of sodium-type montmorillonite {Kunipia P (Kunimine Industries Co., Ltd.)}, which is an inorganic layered substance, was preliminarily dissolved with 0.1 mol of hydrochloric acid and 0.1 mol of diaminododecane at 80 ° C. hot water 10
By adding to L and stirring vigorously, a precipitate of montmorillonite cation-exchanged with ammonium ions (hereinafter referred to as onium-modified montmorillonite A) is obtained. The precipitate is washed with water three times and then dried to obtain onium-modified montmorillonite A powder. As a result of measuring the interlayer distance of the unit crystal layer of this powder by an X-ray diffraction method, the interlayer distance was larger than the interlayer distance of sodium-type montmorillonite before onium modification.

Next, 5 parts by weight of the onium-modified montmorillonite A obtained as described above was added to 150 parts of polymeric MDI having an amine equivalent of 135 in a dry air atmosphere.
An isocyanate mixture in which the onium-modified montmorillonite A is dispersed is obtained by adding it to parts by weight and stirring at 40 ° C. for 6 hours. As for the onium-modified montmorillonite A in this isocyanate mixture, the interlayer distance of the unit crystal layer was measured by the X-ray diffraction method. As a result, the interlayer distance was further expanded by being dispersed in the polymeric MDI.

Next, 100 parts by weight of the hydroxyl value is 390 m.
gKOH / g aromatic amine polyether polyol, 3 parts by weight of foam stabilizer {SZ-1675 (Nippon Unicar Co., Ltd.)}, and 3 parts by weight of catalyst {Kaolizer N
o. 31 (Kao Co., Ltd.)} and 12 parts by weight of cyclopentane and 2 parts by weight of a foaming agent with stirring, and
Prepare a polyol mixture.

Next, 155 parts by weight of the isocyanate mixture and 120 parts by weight of the polyol mixture are mixed and stirred, and foamed by a high-pressure foaming machine, and an insulating box having a space between the outer box and the inner box. Fill the voids in the body to obtain a heat-insulating box. The foaming gas of the polyurethane foam in this example is carbon dioxide gas generated by the reaction between cyclopentane or water and isocyanate, and the reaction profile of polyurethane is such that the cream time is 5 to 8 seconds and the gel time is 35 to 45 seconds. is there.

A test piece of polyurethane foam was cut out from the heat-insulating box thus obtained, and its thermal conductivity,
Compressive mechanical strength and bubble size uniformity were measured. Here, the thermal conductivity is measured by a measuring device {AUTO-Λ (Eiko Seiki Co., Ltd.
Manufactured by the company)}. Compressive mechanical strength is JIS K72
It was measured by 20. The uniformity of foam cell size was observed by scanning electron microscopy of the foam cross section. The measurement results are shown in Table 1 together with the formulation.

Examples 2-3. A heat insulating box filled with polyurethane foam is obtained in the same manner as in Example 1 except that the amount of onium-modified montmorillonite A is changed as shown in Table 1. A polyurethane foam test piece was cut out from the heat insulating box thus obtained, and thermal conductivity, compression mechanical strength, and uniformity of cell size were measured in the same manner as in Example 1. The measurement results are shown in Table 1 together with the formulation.

Example 4. A heat insulating box filled with polyurethane foam is obtained in the same manner as in Example 1 except that montmorillonite (onium-modified montmorillonite B) in which cation exchange is performed using diphenylmethanediamine instead of diaminododecane used in Example 1 is used.
A polyurethane foam test piece was cut out from the heat insulating box thus obtained, and thermal conductivity, compression mechanical strength, and uniformity of cell size were measured in the same manner as in Example 1.
The measurement results are shown in Table 1 together with the formulation.

Example 5. Cation-exchanged montmorillonite (onium) using 3,9-bis (3-aminopropyl) -2,4,8,10-tetrooxaspiro [5,5] undecane in place of the diaminododecane used in Example 1 A heat insulating box filled with polyurethane foam is obtained in the same manner as in Example 1 except that the modified montmorillonite C) is used. A polyurethane foam test piece was cut out from the heat insulating box thus obtained, and thermal conductivity, compression mechanical strength, and uniformity of cell size were measured in the same manner as in Example 1. The measurement results are
The results are shown in Table 1.

Example 6. Instead of diaminododecane used in Example 1, montmorillonite (onium-modified montmorillonite D) cation-exchanged using a polyether polyol obtained by adding propylene oxide to ethylenediamine having an average molecular weight of 700 was used. In the same manner as in 1 above, an insulating box body filled with polyurethane foam is obtained. A polyurethane foam test piece was cut out from the heat insulating box thus obtained, and thermal conductivity, compression mechanical strength, and uniformity of cell size were measured in the same manner as in Example 1. The measurement results are
The results are shown in Table 1.

Example 7. A heat insulating box filled with polyurethane foam is obtained in the same manner as in Example 1 except that montmorillonite (onium-modified montmorillonite E) cation-exchanged with stearylamine is used instead of the diaminododecane used in Example 1. A polyurethane foam test piece was cut out from the heat-insulating box thus obtained, and the thermal conductivity of the test piece was measured in the same manner as in Example 1.
Compressive mechanical strength and bubble size uniformity were measured. The measurement results are shown in Table 1 together with the formulation.

Comparative Example 1. A heat insulating box filled with polyurethane foam is obtained in the same manner as in Example 1 except that 150 parts by weight of polymeric MDI having an amine equivalent of 135 is used instead of the isocyanate mixture. A polyurethane foam test piece was cut out from the heat insulating box thus obtained, and thermal conductivity, compression mechanical strength, and uniformity of cell size were measured in the same manner as in Example 1. The measurement results are shown in Table 1 together with the formulation.

Comparative Example 2.100 parts by weight of hydroxyl value is 39
Aromatic amine polyether polyol of 0 mgKOH / g, 3 parts by weight of a foam stabilizer {SZ-1675 (Nippon Unicar Co., Ltd.)}, and 3 parts by weight of catalyst {Kaolizer No. 31 (Kao Co., Ltd.), 12 parts by weight of cyclopentane and 2 parts by weight of water, and 5 parts by weight of onium-modified montmorillonite A at 40 ° C. in a dry air atmosphere at 6 ° C. By stirring for a time, a polyol mixture in which the onium-modified montmorillonite A is dispersed is obtained. 125 parts by weight of this polyol mixture and 150 parts by weight of a polymeric MDI having an amine equivalent of 135 are mixed and stirred, and foamed by a high-pressure foaming machine to form a space in a heat-insulating box having a space between the outer box and the inner box. Fill the part to obtain a heat-insulating box.

A polyurethane foam test piece was cut out from the heat insulating box thus obtained, and thermal conductivity, compression mechanical strength, and uniformity of cell size were measured in the same manner as in Example 1. The measurement results are shown in Table 1 together with the formulation.

As can be seen from Examples 1 to 7 in Table 1, a polyurethane foam obtained by foaming by mixing an isocyanate mixture in which an onium-modified inorganic layered material is dispersed in an isocyanate compound and a polyol mixture has a urethane reaction in a short time. Polyurethane foam is formed by the method, but the isocyanate mixture and the polyol mixture are uniformly mixed, the onium-modified inorganic layered material is uniformly dispersed, and the same foam as the polyurethane foam containing no inorganic layered material of Comparative Example 1 is used. The size is uniform, and the compression mechanical strength is remarkably improved as compared with the polyurethane foam of Comparative Example 1.

On the other hand, in Comparative Example 2, since the inorganic layered material is dispersed in the polyol, the polyurethane foam obtained by mixing the polyol mixture and the isocyanate compound and foaming the mixture has a difference in viscosity between the isocyanate and the polyol mixture. Is not mixed uniformly, the urethane reaction becomes non-uniform, and the onium-modified inorganic layered material is insufficiently dispersed. Therefore, the polyurethane foam of Comparative Example 2 had a non-uniform cell size, and the polyurethane foam containing no inorganic layered substance of Comparative Example 1
Compressive mechanical strength decreases.

[0040]

[Table 1]

[0041]

According to the first method for producing a polyurethane foam according to the present invention, a polyisocyanate compound in which an inorganic layered substance is dispersed is mixed with a polyol containing a foam stabilizer, a catalyst and a foaming agent to foam the mixture. Thus, it is possible to uniformly mix the polyol and the polyisocyanate compound, and obtain a polyurethane foam having excellent heat insulating properties and mechanical strength.

A second method for producing a polyurethane foam according to the present invention is the same as the first method for producing a polyurethane foam, wherein the inorganic layered material is montmorillonite, saponite, hectorite, beidellite, stevensite, nontronite, vermiculite. , At least one of halloysite, magadiite, kanemite, and mica, and the inorganic layered substance is easily available.

A third method for producing a polyurethane foam according to the present invention is the same as the method for producing a polyurethane foam according to the first or second aspect, wherein the inorganic layered substance has an organic onium ion having a substituent capable of reacting with an isocyanate compound in the molecule. It is modified beforehand with a compound and has excellent dispersibility in polyurethane foam.

The first heat-insulating box body according to the present invention is foamed by the manufacturing method according to any one of claims 1 to 3 in an outer box, an inner box, and a gap between the outer box and the inner box. , Which is composed of filled polyurethane foam, and because polyurethane foam has excellent heat insulating properties and strong mechanical strength,
The space between the outer box and the inner box can be narrowed, and the effective volume can be increased.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 3E067 BA05A BB17A BC06A CA18                       FA01 FC01 GA11 GD01 GD10                 4J034 DA01 DA03 DF14 DG03 DG04                       DG23 HA01 HA02 HA06 HA07                       HA08 HC12 HC13 HC22 HC46                       HC52 HC54 HC61 JA01 JA24                       MA01 NA01 NA03 NA06 QC01                       QC03 QD03 RA06 SA02 SB04                       SB05

Claims (4)

[Claims] 1. A method for producing a polyurethane foam in which a polyol containing a foam stabilizer, a catalyst and a foaming agent is mixed with a polyisocyanate compound in which an inorganic layered material is dispersed to foam the mixture. 2. The inorganic layered material is at least one of montmorillonite, saponite, hectorite, beidellite, stevensite, nontronite, vermiculite, halloysite, magadiite, kanemite and mica. The method for producing a polyurethane foam according to claim 1. 3. The inorganic layered material is preliminarily modified with an organic onium ion compound having a substituent capable of reacting with an isocyanate compound in the molecule.
2. The method for producing a polyurethane foam according to 2 above. 4. A heat insulation comprising an outer box, an inner box, and a polyurethane foam that is foamed and filled in the gap between the outer box and the inner box by the manufacturing method according to claim 1. Box.