Rigid polyurethane foam

Abstract

To reduce thermal conductivity of a rigid polyurethane foam relative to conventional levels.SOLUTION: A rigid polyurethane foam contains a first structural unit derived from a polyol and a second structural unit derived from an isocyanate, the rigid polyurethane foam containing fine particles having a thermal conductivity lower than that of a polyurethane resin containing the first structural unit and the second structural unit, and a third structural unit having a higher degree of stereostructural freedom than the first structural unit and the second structural unit.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a rigid polyurethane foam that can be used, for example, as a heat insulating material for a refrigerator. [Background technology]

[0002] In order to further reduce the thermal conductivity of rigid polyurethane foam, it has been considered to incorporate porous fine particles such as aerogel or aerosil into the polyurethane foam, as disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2014-502305 Summary of the Invention [Problem to be solved by the invention]

[0004] However, as a result of actual experiments conducted by the present inventors, it was found that simply incorporating microparticles, as described in the aforementioned patent documents, was not enough to sufficiently reduce the thermal conductivity of rigid polyurethane foam.

[0005] The present invention has been made in view of the above problems, and its main object is to further reduce the thermal conductivity of rigid polyurethane foams compared to conventional ones. [Means for solving the problem]

[0006] That is, the rigid polyurethane foam according to the present invention is as follows. [1] A rigid polyurethane foam containing a first structural unit derived from a polyol and a second structural unit derived from an isocyanate, fine particles having a thermal conductivity lower than that of a polyurethane resin containing the first structural unit and the second structural unit; A rigid polyurethane foam comprising: the first structural unit; and a third structural unit having a higher degree of freedom in terms of three-dimensional structure than the second structural unit. [2] The rigid polyurethane foam according to [1], wherein the third structural unit is a structural unit derived from a polyol and / or a structural unit derived from a surfactant. [3] The rigid polyurethane foam according to [1] or [2], wherein the third constitutional unit contains a linear structure. [4] The rigid polyurethane foam according to any one of [1] to [3], wherein the molecular weight of the third constitutional unit is 50 or more and 500 or less. [5] The rigid polyurethane foam according to any one of [1] to [4], wherein the content of the third constitutional unit is 0.5% by mass or more and 5% by mass or less, based on 100% by mass of the rigid polyurethane foam. [6] The rigid polyurethane foam according to any one of [1] to [5], wherein the fine particles are chemically bonded to the urethane resin. [7] The rigid polyurethane foam according to any one of [1] to [6], wherein the content of the fine particles is 0.01% by volume or more and 0.5% by volume or less, based on 100% by volume of the rigid polyurethane foam. [8] The rigid polyurethane foam according to any one of [1] to [7], wherein the content of the fine particles is 0.1% by mass or more and 1.5% by mass or less, based on 100% by mass of the rigid polyurethane foam. [9] The rigid polyurethane foam according to any one of [1] to [8], wherein the surfaces of the fine particles are modified with a compound containing a hydrophilic group and a hydrophobic group.

[10] The rigid polyurethane foam according to any one of [1] to [9], wherein the fine particles have an average particle size of 0.03 μm or more and 20 μm or less.

[11] The bulk density of the fine particles is 200 kg / m 3 The rigid polyurethane foam according to any one of [1] to

[10] , which is:

[12] The rigid polyurethane foam according to any one of [1] to

[11] , wherein the first structural units contain structural units derived from an aliphatic non-aromatic amine compound having 2 to 4 functional groups and having ethylene oxide added thereto in an amount of 1% by mass to 10% by mass, and structural units derived from an aromatic amine compound having 4 to 6 functional groups and having both ethylene oxide and propylene oxide added thereto in an amount of 65% by mass to 99% by mass.

[13] The rigid polyurethane foam according to any one of [1] to

[11] , wherein the first structural unit contains structural units derived from a compound of an aromatic dicarboxylic acid having 2 to 4 functional groups and having a diol added thereto in an amount of 1% by mass to 10% by mass.

[14] A method for producing a rigid polyurethane foam according to any one of [1] to

[13] , a premix containing a material constituting the first constitutional unit, a material constituting the third constitutional unit, a foaming agent, and fine particles; A method for producing a rigid polyurethane foam, comprising mixing the material constituting the second structural unit with the material constituting the second structural unit to produce a rigid polyurethane foam.

[15] The method for producing a rigid polyurethane foam according to

[14] , wherein the viscosity of the premix is ​​500 mPa·s or more and 2000 mPa·s or less. [Effects of the Invention]

[0007] According to the present invention, the rigid polyurethane foam contains fine particles having a lower thermal conductivity than the urethane resin and a third constituent unit having a higher degree of freedom in three-dimensional structure than the first and second constituent units that constitute the urethane resin, thereby making it possible to further reduce the thermal conductivity of the rigid polyurethane foam compared to conventional products. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing how bubble growth is suppressed in a rigid polyurethane foam according to one embodiment of the present invention. FIG. [Figure 2]1 is a schematic diagram showing the structure of a rigid polyurethane foam according to this embodiment and a conventional rigid polyurethane foam. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of the present invention will be described in detail below with reference to the drawings. <Configuration of the rigid polyurethane foam according to this embodiment> The rigid polyurethane foam according to this embodiment is produced by foaming and curing to form numerous bubbles inside. This foaming and curing can be produced by reacting a polyol, which is a raw material for the first structural unit contained in the rigid polyurethane foam, with an isocyanate, which is a raw material for the second structural unit, to produce a polyurethane resin containing the polyol-derived first structural unit and the isocyanate-derived second structural unit, and then foaming with a blowing agent.

[0010] The rigid polyurethane foam according to this embodiment preferably has a density of 30 kg / m or more and 45 kg / m or less, more preferably 32 kg / m or more and 40 kg / m or less, and even more preferably 32 kg / m or more and 38 kg / m or less. Rigid polyurethane foam is a urethane foam that loses its restoring properties and cushioning properties after hardening, and is often used for heat insulation purposes.

[0011] The first structural unit is a chemical structural unit obtained after the polyol that serves as the material for the first structural unit is incorporated into the polyurethane resin. Examples of the polyol that serves as the material for the first structural unit include polyether polyol and / or polyester polyol.

[0012] The polyol used as the material for the first structural unit preferably contains a structural unit derived from an aromatic amine compound having 4 to 6 functional groups and having both ethylene oxide and propylene oxide added thereto. Specific examples of the structural unit derived from an aromatic amine compound include 2,3-toluenediamine, 2,4-toluenediamine, and 2,6-toluenediamine. The content of the structural unit derived from an aromatic amine compound is preferably in the range of 65% to 99% by mass, where the entire polyol used as the material for the first structural unit is taken as 100% by mass.

[0013] The polyol used as the material for the first structural unit may contain a structural unit derived from an aliphatic non-amine compound having two or more and four or less functional groups and having ethylene oxide added thereto. Specific examples of structural units derived from aliphatic non-aromatic amine compounds include ethylene glycol, propylene glycol, glycerin, and pentaerythritol. In this case, the content of the structural unit derived from the aliphatic non-aromatic amine compound is preferably in the range of 1% by mass to 10% by mass, where the total amount of the polyol used as the material for the first structural unit is taken as 100% by mass. By including a non-aromatic amine compound in the polyol used as the material for the first structural unit in the above-mentioned range, steric hindrance due to aromatic rings can be suppressed, thereby improving the strength of the cell film. As a result, the cells can be made finer and high gas barrier properties can be imparted, which is believed to further reduce the thermal conductivity of the rigid polyurethane foam.

[0014] The polyol that is the material for the first structural unit may be an aromatic dicarboxylic acid having two or more and four or less functional groups, and may contain a structural unit derived from a compound to which a diol is added. Specific examples of the aromatic dicarboxylic acid that constitutes the structural unit derived from a compound to which a diol is added include phthalic anhydride and terephthalic acid. Examples of diols that can be used include diethylene glycol, 1,4-butanediol, 1,3-propanediol, and 3-methyl-1,5-pentanediol.

[0015] The polyol that is the material for the first structural unit may contain only one type of structural unit selected from the group consisting of structural units derived from the aromatic amine compounds described above, structural units derived from aliphatic non-aromatic amine compounds, and structural units derived from aromatic dicarboxylic acids to which a diol has been added, or may contain two or more types of structural units.

[0016] For example, the polyol from which the first structural unit is derived may contain structural units derived from an aromatic amine compound and structural units derived from an aromatic dicarboxylic acid compound to which a diol has been added. By containing structural units derived from an aromatic amine compound and structural units derived from an aromatic dicarboxylic acid compound to which a diol has been added, the aromatic rings of these structural units stack together, further improving the strength of the cell membrane. As a result, the cells can be made finer and high gas barrier properties can be imparted, which is thought to further reduce the thermal conductivity of the rigid polyurethane foam.

[0017] When the polyol that is the material for the first structural units contains structural units derived from an aromatic amine compound and structural units derived from an aromatic dicarboxylic acid compound having a diol added thereto, it preferably contains structural units derived from an aromatic amine compound in a range of 65% by mass to 99% by mass, and structural units derived from an aromatic dicarboxylic acid compound having a diol added thereto in a range of 1% by mass to 10% by mass, where the entire polyol that is the material for the first structural units is taken as 100% by mass.

[0018] As the isocyanate that is the material for the second constitutional unit, any of those that have been conventionally used in rigid polyurethane foams can be used, but in this embodiment, it is preferable to use polymeric MDI.

[0019] The rigid polyurethane foam according to this embodiment further contains fine particles.

[0020] The fine particles have a lower thermal conductivity than the polyurethane resin containing the first constitutional units and the second constitutional units. The thermal conductivity of the fine particles is, for example, preferably 50 mW / m·K or less, more preferably 30 mW / m·K or less, and particularly preferably 20 mW / m·K or less.

[0021] The shape of the fine particles may be any of spherical, spheroidal, other geometric shapes, irregular shapes, etc., but spherical or spheroidal shapes are preferred. More preferably, the shape factor, which is the quotient obtained by dividing the sum of the major axis ratio (the value obtained by dividing the major axis length by the minor axis length) and the roughness coefficient (the value obtained by dividing the cross-sectional area in a plane including the major and minor axes by the square of the perimeter) by 2, is 120 or less.

[0022] The microparticles preferably have, for example, an air layer (core), a spherical or polygonal shell, and a surface layer formed to cover the surface of the shell, and are chemically bonded to the polyurethane resin contained in the rigid polyurethane foam via the surface layer. The chemical bond is not particularly limited, but is preferably a covalent bond.

[0023] The shell is preferably made of an inorganic material having excellent strength and heat resistance, and examples thereof include hollow particles, porous particles, aerogels, xerogels, and the like made of oxides such as silica and alumina.

[0024] The surface layer is formed by, for example, a modifying group fixed to the shell via a chemical bond such as a covalent bond.

[0025] The modifying group can be appropriately used depending on the required performance, and a modifying group containing only a hydrophilic group or a modifying group having both a hydrophobic group and a hydrophilic group can be preferably used.

[0026] The modifying group preferably contains one or more hydrophilic groups, or one or more hydrophobic groups and one or more hydrophilic groups. More preferably, it is a linear group in which a bonding group for chemically bonding the shell and the modifying group, a hydrophobic group, and a hydrophilic group are bonded in this order from the side closer to the shell. Furthermore, it may have a structure in which a bonding group, a hydrophobic group, and a hydrophilic group are arranged from the side closer to the shell, and then a hydrophobic group is further present, or a structure in which pairs of hydrophobic groups and hydrophilic groups are repeated. The surface layer may be composed of only one type of modifying group as described above, or may contain two or more types of modifying groups as described above.

[0027] The binding group may be any group that can chemically bond the shell and the modifying group. For example, if the shell is made of silica, a silane compound such as 3-aminopropyltriethoxysilane may be used. Examples of the hydrophobic group include linear hydrocarbon groups having 1 to 10 carbon atoms, such as an ethyl group, a methyl group, and a propyl group, or cyclic hydrocarbon groups such as a benzene ring. The hydrophilic group preferably has an amino group or a hydroxyl group.

[0028] One modifying group derived from one molecule of the surface treatment agent may contain one or more of the above-mentioned hydrophobic groups, or may contain one or more of the above-mentioned hydrophilic groups. Furthermore, when multiple types of hydrophobic groups and / or hydrophilic groups are contained in one modifying group, the order and number of these groups arranged may be any as long as the structure is such that a binding group is first provided, followed by alternating hydrophobic groups and hydrophilic groups.

[0029] The surface layer described above can be formed by surface-treating the shell with a surface treatment agent such as a silane coupling agent having a hydrophobic group and / or a hydrophilic group. More specifically, the surface layer may be formed by chemically bonding the shell surface and the surface treatment agent to each other via a covalent bond or the like, so that a large number of the modifying groups are arranged to cover the surface of the shell. When the surface treatment agent is linear, it is preferable that the modifying groups derived from the surface treatment agent are arranged so as to extend outward from the surface of the shell.

[0030] In this embodiment, when the mass of the entire rigid polyurethane foam is taken as 100% by mass, the content of the microparticles is preferably 0.1% by mass or more and 1.5% by mass or less, more preferably 0.1% by mass or more and 1.4% by mass or less, and even more preferably 0.2% by mass or more and 1.3% by mass or less.

[0031] Furthermore, when the volume of the entire rigid polyurethane foam is taken as 100% by volume, the content of the microparticles is preferably 0.01% by volume or more and 0.5% by volume or less, more preferably 0.05% by volume or more and 0.4% by volume or less, and even more preferably 0.1% by volume or more and 0.3% by volume or less.

[0032] By specifying the content of microparticles as the volume ratio of the microparticles to the volume of the rigid polyurethane foam after foaming and curing, as described above, it is possible to ensure that the number of microparticles necessary to make the cells fine is present in the microparticle-containing rigid polyurethane foam, even if the type of microparticle is changed.As shown in Figure 1, this allows for reliable control of bubble growth and improves the insulating effect.

[0033] By setting the content of microparticles at 0.01% by volume or more, the bubbles can be made smaller without fail. Also, by setting the content of microparticles at 0.5% by volume or less, the viscosity of the mixture, which is the material for the rigid polyurethane foam before foaming and curing, can be prevented from becoming too high, and the increase in thermal conductivity caused by large bubbles generated in the urethane foam remaining trapped and forming voids can be suppressed.

[0034] The bulk density of the fine particles is 200 kg / m 3 It is preferable that the bulk density of the fine particles is 200 kg / m or less. 3 If the bulk density of the fine particles is less than 100%, the viscosity of the mixture will not be too high, and the occurrence of voids described above can be further suppressed, which is preferable. Since the lower the bulk density of the fine particles, the better the heat insulating performance of the polyurethane foam.

[0035] The bulk density can be calculated by gently placing 100 g of fine powder into a measuring cylinder, smoothing the top surface, and reading the bulk volume V0 (unit: ml). The bulk density (g / ml) can then be calculated by converting the unit.

[0036] The average particle size of the microparticles is preferably 0.03 μm or more and 20 μm or less. When the average particle size of the microparticles is 0.03 μm or more, the bubble growth suppression effect due to the presence of the microparticles can be fully exerted, which is preferable. Furthermore, when the average particle size of the microparticles is 20 μm or less, the number of microparticles contained in the rigid polyurethane foam can be sufficiently secured, which can fully exert the bubble growth suppression effect. The average particle size of the microparticles can be measured by observation with a scanning electron microscope.

[0037] The rigid polyurethane foam according to this embodiment further contains a third constitutional unit that constitutes the polyurethane resin together with the first constitutional unit and the second constitutional unit.

[0038] The third constitutional unit is a constitutional unit having a higher degree of freedom in its steric structure than the first constitutional unit and the second constitutional unit. A high degree of freedom in the steric structure means, for example, that the chemical structure of the third constitutional unit is a chain structure that is stretchable in the length direction of the chain structure and / or has a structure with little steric hindrance due to side chains.

[0039] As described above, in a chain structure, examples of compounds that can be used as materials for obtaining a third constituent unit that has a high degree of freedom in its longitudinal direction of expansion and contraction include compounds that have a structure in which polyolefin is the main chain within the molecule and that can form a covalent bond such as a urethane bond with the material that constitutes the first constituent unit or the second constituent unit.

[0040] The compound that serves as the material for the third constitutional unit preferably has functional groups that can form covalent bonds, such as urethane bonds, at both ends of the chain structure described above. Examples of compounds that serve as materials for the third constitutional unit include polyols and surfactants that have a linear structure with relatively small side chains.

[0041] Specific examples of polyols that are materials for the third constitutional units include polyethers such as polyethylene glycol and polypropylene glycol.

[0042] Examples of the surfactant include nonionic surfactants and silicone surfactants.

[0043] The molecular weight of the third constitutional unit derived from these compounds is preferably 50 or more and 500 or less, and more preferably 100 or more and 400 or less.

[0044] In this specification, the term "straight chain" means that there are no side chains, or even if there are side chains, the length of the side chains relative to the main chain is sufficiently short so as not to inhibit the degree of freedom (for example, flexibility) in the three-dimensional structure of the main chain.

[0045] Furthermore, the first constitutional unit, the second constitutional unit, and the third constitutional unit are incorporated into the polyurethane resin of the rigid polyurethane foam while maintaining the original chemical structure of the compound that constitutes each of them, except for the functional groups at both ends that are used to form urethane bonds.

[0046] The content of the third constitutional unit in the rigid polyurethane foam is preferably 0.5% by mass or more and 5% by mass or less, and more preferably 0.6% by mass or more and 4% by mass or less, when the entire rigid polyurethane foam is taken as 100% by mass.

[0047] <Method for producing rigid polyurethane foam according to this embodiment> The rigid polyurethane foam according to this embodiment can be produced, for example, by the following procedures and steps.

[0048] First, a mixture containing the material for the first structural unit and the material for the third structural unit is prepared. Next, this mixture is mixed with fine particles at room temperature and open to the atmosphere, and then a foaming agent is added and mixed in an enclosed space at 20°C to 25°C to prepare a premix.

[0049] From the viewpoint of improving workability when pouring into a mold and foaming and hardening, it is preferable that the viscosity of the premix be 500 mPa·s or more and 2000 mPa·s or less. This preferable viscosity of the premix is ​​measured at 20°C using a TVC-10 manufactured by Toki Sangyo.

[0050] After the material for the second structural unit is added to the premix and stirred, the mixture is poured into an appropriate mold and allowed to foam freely, thereby producing a rigid polyurethane foam.

[0051] Although a wide variety of blowing agents conventionally used in rigid polyurethane foams can be used, it is particularly preferred to use organic solvents with relatively low boiling points, such as cyclopentane, as the blowing agent. Specifically, it is preferred to use blowing agents with boiling points of 55°C or less, and particularly preferred to use blowing agents with boiling points of 50°C or less.

[0052] The premix preferably further contains a foaming aid, and the content of the foaming aid in the premix is ​​0.5% by mass or more and 2.0% by mass or less. The foaming aid is not particularly limited, but is preferably water, from the viewpoint of achieving both high reaction efficiency and low cost.

[0053] The premix may further contain additives such as a catalyst and a foam stabilizer (binder) in addition to the above-mentioned components.

[0054] Examples of the catalyst include a resinification catalyst, a foaming catalyst, a trimerization catalyst, etc. If these catalysts contain a tertiary amine, it is possible to produce a rigid polyurethane foam that is as environmentally friendly as possible while keeping production costs down, and this is preferred.

[0055] As the foam stabilizer, any foam stabilizer conventionally used in rigid polyurethane foams can be used, but it is preferable to use a silicone-based foam stabilizer.

[0056] <Effects of this embodiment> The present inventors have attempted to reduce the overall thermal conductivity of rigid polyurethane foam by incorporating microparticles into the foam, but have found that the thermal conductivity of the rigid polyurethane foam is in some cases barely reduced compared to when the microparticles are not incorporated. In particular, when the microparticles are chemically bonded to the urethane resin, a reduction in thermal conductivity is expected because the microparticles are effectively used to inhibit bubble growth. However, it has been found that in such cases, the reduction in thermal conductivity is not as great as expected. In this regard, the rigid polyurethane foam according to the present embodiment uses a third structural unit with a structure that has minimal steric hindrance. Furthermore, as shown in FIG. 2, the third structural unit is covalently bonded to the first or second structural unit, which have a relatively low degree of freedom and a rigid structure, to form the polyurethane resin, thereby increasing the three-dimensional structural freedom of the polyurethane resin as a whole. As a result, even when the microparticles are incorporated, the expansion ratio during foaming of the rigid polyurethane foam can be maximized, and the overall thermal conductivity of the rigid polyurethane foam can be kept significantly lower than conventional structures.

[0057] For example, when this rigid polyurethane foam is used as a heat insulating material for a refrigerator, it is necessary to inject the rigid polyurethane foam into the long and narrow gap between the outer and inner boxes of the refrigerator and allow it to foam and harden. Even in cases where the rigid polyurethane foam is injecting into a long and narrow space and allowing it to foam and harden, if the rigid polyurethane foam contains the third constitutional unit having a high degree of freedom in three-dimensional structure as described above, the expansion ratio can be increased compared to conventional methods, as described above, and the rigid polyurethane foam can be easily filled into the gap (improved filling ability).

[0058] The rigid polyurethane foam according to this embodiment can be used for various purposes as a heat insulating material. Since the thermal conductivity is sufficiently low and the manufacturing cost can be kept within an appropriate range, it can be suitably used, for example, as a heat insulating material for home appliances such as refrigerators.

[0059] The present invention is not limited to the above-described embodiment, and various modifications and combinations of the embodiments may be made as long as they do not deviate from the spirit of the present invention. [Example]

[0060] The present invention will be described in more detail below based on specific examples. However, the following examples are merely examples of the present invention, and the present invention is not limited to the following examples.

[0061] First, mixed solutions with the compositions listed in Table 1 below were prepared. The mixtures, adjusted to a liquid temperature of 25°C, were stirred with a hand mixer at 5,000 rpm for 4 seconds. The viscosity of each mixed solution after stirring was approximately 700 mPa·s. The mixed solutions were poured into a 300 mm × 300 mm × 50 mm wooden box whose temperature was adjusted to 42 to 44°C, and allowed to freely foam to produce the rigid polyurethane foams of the Examples and Comparative Examples. Almost all of the materials used for the first, second, and third constituent units were used to form the rigid polyurethane foam. Table 2 shows the volume percentages of each component, assuming the volume of each rigid polyurethane foam after foaming and curing to be 100% by mass.

[0062] [Table 1] All values ​​in Table 1 are in mass %. The specific details of each component in Table 1 are as follows: Polyol premix: 100 parts by mass of polyol (70% by mass of aromatic amine polyol + 30% by mass of sorbitol polyol) + 3.0 parts by mass of tertiary amine catalyst + 2.5 parts by mass of silicone foam stabilizer + 1.8% by mass of water. The polyol contained in the polyol premix is ​​the material of the first constituent unit. Foaming agent: Marukasol FH (Maruzen Petrochemical Co., Ltd.) Isocyanate (material of the second structural unit): MR-200 Index 110 (manufactured by Tosoh Corporation) Hollow particles: Hollow silica (average particle size (D50): 2 μm) PEG200 or PEG600 (material of the third building block) Silicone surfactants or nonionic surfactants (dispersants)

[0063] [Table 2] In Table 2, the units of values ​​without unit indication are vol%. The volume of the rigid polyurethane foam in Table 2 was calculated from the density of each rigid polyurethane foam and the total mass of the polyol, blowing agent, and isocyanate in Table 1. The volume of the other components was calculated from the density and mass of each component. The density of each rigid polyurethane foam was measured by the following method. <Measurement of the overall density of microparticle rigid polyurethane foam> The weight of a rigid polyurethane foam measuring 300 mm x 300 mm x 50 mm thick was measured using an electronic balance, and the density of the entire foam was calculated from the total volume of the rigid polyurethane foam.

[0064] Next, the performance of these Examples and Comparative Examples was evaluated by the following methods. <Measurement of thermal conductivity> The thermal conductivity of the foamed and cured rigid polyurethane foams of each Example and Comparative Example, each measuring 300 mm x 300 mm x 50 mm thick, was measured at an average temperature of 20°C using a NETZSCH steady-state thermal conductivity measuring device (HFM436). The results are shown in Table 3.

[0065] [Table 3]

[0066] The results in Table 3 show that the rigid polyurethane foams of Examples 1 to 12, which contain the third structural unit, are able to achieve lower thermal conductivity than not only Comparative Example 1, which does not contain microparticles, but also Comparative Example 2, which contains microparticles.

[0067] Next, assuming that the rigid polyurethane foam is used by filling gaps, such as when used as a heat insulating material for a refrigerator, the filling property was evaluated by the following method. <Flow length (filling ability)> Among the examples and comparative examples listed in Table 1, Examples 1 to 7 and Comparative Example 1 For Example 1 and Comparative Example 2, a fixed amount of each mixed solution was allowed to freely foam in an aluminum mold measuring 1000 mm in height, 175 mm in width, and 25 mm in depth and temperature-controlled at 42 to 44°C, and the height of each rigid polyurethane foam after foaming and curing was measured. The height of the rigid polyurethane foam of Comparative Example 1 containing no microparticles, measured by this method, was defined as 100%, and the heights of the rigid polyurethane foams of the other Examples and Comparative Examples were evaluated. The results are shown in Table 4.

[0068] [Table 4]

[0069] The results in Table 4 show that in Comparative Example 2, in which only microparticles were contained in the rigid polyurethane foam, the height of the rigid polyurethane foam after foaming and hardening was smaller than in Comparative Example 1, in which no microparticles were contained. This shows that in Comparative Example 2, the expansion ratio of the rigid polyurethane foam was reduced due to the inclusion of microparticles. On the other hand, in Examples 1 to 7, which contain the third structural unit in addition to the microparticles, the reduction in height of the rigid polyurethane foam was kept much smaller than in Comparative Example 2, and it was confirmed that Examples 1 to 7 were able to maintain an expansion ratio equivalent to that of Comparative Example 1, which does not contain microparticles, and had sufficient filling properties.

Claims

1. A rigid polyurethane foam containing a first structural unit derived from a polyol and a second structural unit derived from an isocyanate, fine particles having a thermal conductivity lower than that of a polyurethane resin containing the first structural unit and the second structural unit; A rigid polyurethane foam comprising: the first structural unit; and a third structural unit having a higher degree of freedom in terms of three-dimensional structure than the second structural unit.

2. The rigid polyurethane foam according to claim 1, wherein the third structural unit is a structural unit derived from a polyol and / or a structural unit derived from a surfactant.

3. 2. The rigid polyurethane foam according to claim 1, wherein the third structural unit comprises a linear structure.

4. 2. The rigid polyurethane foam according to claim 1, wherein the molecular weight of the third constitutional unit is 50 or more and 500 or less.

5. 2. The rigid polyurethane foam according to claim 1, wherein the content of the third constitutional unit is 0.5% by mass or more and 5% by mass or less, based on 100% by mass of the rigid polyurethane foam.

6. 2. The rigid polyurethane foam according to claim 1, wherein the microparticles are chemically bonded to the urethane resin.

7. 2. The rigid polyurethane foam according to claim 1, wherein the content of said fine particles is 0.01% by volume or more and 0.5% by volume or less, based on 100% by volume of the rigid polyurethane foam.

8. 2. The rigid polyurethane foam according to claim 1, wherein the content of the fine particles is 0.1% by mass or more and 1.5% by mass or less, based on 100% by mass of the rigid polyurethane foam.

9. 2. The rigid polyurethane foam according to claim 1, wherein the surfaces of the fine particles are modified with a compound containing a hydrophilic group and a hydrophobic group.

10. 2. The rigid polyurethane foam according to claim 1, wherein the fine particles have an average particle size of 0.03 μm or more and 20 μm or less.

11. 2. The rigid polyurethane foam according to claim 1, wherein the fine particles have a bulk density of 200 kg / m or less.

12. 2. The rigid polyurethane foam according to claim 1, wherein the first structural units contain structural units derived from an aliphatic non-aromatic amine compound having 2 or more and 4 or less functional groups and having ethylene oxide added thereto in a range of 1% by mass to 10% by mass, and structural units derived from an aromatic amine compound having 4 or more and 6 or less functional groups and having both ethylene oxide and propylene oxide added thereto in a range of 65% by mass to 99% by mass.

13. 2. The rigid polyurethane foam according to claim 1, wherein the first structural unit is an aromatic dicarboxylic acid having 2 or more and 4 or less functional groups, and contains a structural unit derived from a compound to which a diol is added in an amount of 1% by mass to 10% by mass.

14. A method for producing the rigid polyurethane foam according to any one of claims 1 to 13, comprising: a step of preparing a premix by mixing a material constituting the first constitutional unit, a material constituting the third constitutional unit, a foaming agent, and fine particles; and mixing the premix with a material that constitutes the second structural unit to foam and harden a rigid polyurethane foam.

15. 15. The method for producing a rigid polyurethane foam according to claim 14, wherein the viscosity of the premix is ​​500 mPa·s or more and 2000 mPa·s or less.

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