Phenolic resin foam

Abstract

To provide a phenol resin foam which is excellent in alkali resistance, can be suitably used in a concrete placing method such as a wet external heat insulation method, and is applied as a heat insulating material for construction.SOLUTION: A phenolic resin foam satisfying the following (1), (2), and (3) and having a closed-cell ratio of 80% or more and a foam density of 20 to 80kg / m3: (1) The presence ratio of the metal compound in the outermost layer of the phenolic resin foam is from 0.5 to 25.0%. (2) The presence ratio of the metal compound in the center layer of the phenol resin foam is 0.5 to 15.0%. (3) The phenolic resin foam has an average bubble size of 50 to 120 μm in a cross section obtained by horizontally cutting the phenolic resin foam at the 5mm in the thickness direction from the outermost layer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a phenolic resin foam that has excellent alkali resistance and is suitable for use as a thermal insulating material for construction in concrete pouring methods such as wet external thermal insulation methods. [Background technology]

[0002] Traditionally, glass wool and foamed resin moldings have been widely used as building insulation materials. There are two known types of exterior insulation methods: dry exterior insulation and wet exterior insulation. Inexpensive glass wool has mainly been used in the dry exterior insulation method. However, when glass wool absorbs moisture from within the wall and becomes heavy, it loses its shape and sags toward the bottom of the wall, making it difficult to maintain its shape for long periods of time, resulting in a significant decline in its insulating effectiveness over the long term.

[0003] On the other hand, Patent Document 1 discloses a wet external insulation method in which a mortar layer is provided on an insulation board made of a foamed resin molded body or the like, and a glass fiber mesh is arranged and mortar is provided on the surface.

[0004] The wet external insulation method described in Patent Document 1 uses glass fiber mesh as a mesh with a mortar layer on top of the insulation material. The placement of the glass fiber mesh can prevent the insulation material and the mortar layer above it from peeling off. However, there are cases where the strength of the glass fiber mesh itself is insufficient, or where the strength of the glass fiber mesh is reduced by alkaline components from the mortar, resulting in the problem of the mortar layer peeling off over the long term.

[0005] Phenolic resin foam has been used as a thermal insulation material for construction applications due to its flame retardancy and long-term thermal insulation performance. However, phenolic resin foam has a fairly high alkali concentration, and under harsh usage conditions such as high temperature and humidity, it is preferable for the foam to have higher alkali resistance. Under such conditions, if mortar is directly laminated to the phenolic resin foam, there is a risk that the strength of the phenolic resin foam itself will decrease, resulting in the mortar falling off after construction.

[0006] Another possible method for solving the problem of alkali-induced deterioration of phenolic resin foam is to reduce the water absorption rate of the foam to make it difficult for alkali components to penetrate into the foam. Patent Document 2 discloses a method for reducing the amount of water absorption by adding a specific metal salt to phenolic resin foam. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-231723 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-131859 Summary of the Invention [Problem to be solved by the invention]

[0008] Patent Document 2 discloses calcium carbonate as a metal salt to be added to a phenolic resin foam, but there is a problem in that the proportion of calcium carbonate present in the surface layer of the phenolic resin foam is insufficient, making it impossible to sufficiently suppress deterioration due to alkali.

[0009] Therefore, an object of the present invention is to provide a phenolic resin foam having excellent heat insulating properties while improving the alkali resistance of the surface layer of the phenolic resin foam. [Means for solving the problem]

[0010] As a result of extensive research to achieve the above object, the inventors have discovered a method for improving alkali resistance compared to conventional phenolic resin foams while maintaining excellent heat insulating performance by adding a specific metal compound to a phenolic resin and increasing the content of the metal compound, particularly in the outermost layer that comes into contact with alkali, and have completed the present invention.

[0011] [1] Satisfying the following (1), (2), and (3), with a closed cell rate of 80% or more and a foam density of 20 to 80 kg / m 3 Phenolic resin foam. (1) The content of the metal compound in the outermost layer of the phenolic resin foam is 0.5 to 25.0%. (2) The content of the metal compound in the central layer of the phenolic resin foam is 0.5 to 15.0%. (3) The average cell diameter of a cross section of the phenolic resin foam cut parallel to the outermost layer at a position 5 mm from the outermost layer in the thickness direction is 50 to 120 μm. [2] The phenolic resin foam according to [1], having a thermal conductivity of 0.0260 W / (m·K) or less at 23°C. [3] The phenolic resin foam according to [1] or [2], wherein the proportion of the metal compound in the outermost layer of the phenolic resin foam is greater than the proportion of the metal compound in the central layer of the phenolic resin foam. [4] The phenolic resin foam according to any one of [1] to [3], wherein the metal of the metal compound is at least one selected from the group consisting of calcium, magnesium, zinc, barium, aluminum, iron, sodium, and potassium, and is one or more metal compounds formed in combination with at least one selected from the group consisting of oxides, chlorides, sulfates, and carbonates. [5] The phenolic resin foam according to any one of [1] to [4], which has a strength retention rate of 30% or more of tensile strength after an alkali resistance test. [Effects of the Invention]

[0012] According to the present invention, by efficiently distributing a specific metal compound in the thickness direction of a phenolic resin foam, a phenolic resin foam having excellent alkali resistance and a method for producing the same can be provided. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. However, the present invention is not limited to the following embodiment.

[0014] In this embodiment, the metal element of the metal compound is preferably one selected from the group consisting of calcium, magnesium, zinc, barium, aluminum, iron, sodium, and potassium. The metal compound is preferably selected from the group consisting of oxides, chlorides, sulfates, and carbonates of the aforementioned metals. Among these, calcium sulfate, magnesium sulfate, iron sulfate, sodium sulfate, and potassium sulfate are more preferred, with calcium sulfate being the most preferred. These metal compounds may be used alone or in combination. The metal compounds contained in the phenolic resin foam can be identified using commonly used techniques such as X-ray diffraction (XRD).

[0015] In this embodiment, the metal compound content in the outermost layer of the phenolic resin foam is in the range of 0.5 to 25.0%, preferably 0.5 to 20.0%, more preferably 1.0 to 20.0%, even more preferably 3.0 to 20.0%, and most preferably 5.0 to 20.0%. By adding a metal compound in this range to the outermost layer, sufficient alkali resistance can be achieved even with a small amount. A metal compound content below 0.5% is insufficient in the outermost layer, failing to provide sufficient alkali resistance. Furthermore, a metal compound content above 25.0% is undesirable because it may degrade the heat insulating performance due to the heat conduction of the metal compound and may even cause the cell membrane to break from the metal compound, resulting in a lower closed cell ratio. Here, the outermost layer of the phenolic resin foam refers to the outermost layer on the surface perpendicular to the thickness direction of the phenolic resin foam. The metal compound content is determined by averaging the results of evaluations of the top and bottom surfaces. The method for measuring the proportion of the metal compound present in the outermost layer will be specifically explained in the examples described later.

[0016] In the phenolic resin foam of this embodiment, the content of the metal compound in the central layer is in the range of 0.5 to 15.0%, preferably 0.5 to 10.0%, more preferably 3.0 to 10.0%, and most preferably 5.0 to 10.0%. If the content of the metal compound in the central layer exceeds 15.0%, the cell membranes are more likely to be ruptured starting from the metal compound, which can lead to a decrease in the closed cell content and thermal conductivity of the phenolic resin foam. Therefore, it is not preferable for the content of the metal compound in the central layer to exceed 15.0%. Furthermore, if the content of the metal compound in the central layer is less than 0.5%, the content of the metal compound in the outermost layer of the phenolic resin foam will naturally be reduced, making it difficult to obtain the desired effect of adding the metal compound. Therefore, it is not preferable for the content of the metal compound in the central layer to be less than 0.5%. Here, the central layer refers to a layer located at the center of the phenolic resin foam in the thickness direction and parallel to the outermost layer. The method for measuring the proportion of the metal compound in the core layer will be specifically explained in the examples described later.

[0017] In the phenolic resin foam of this embodiment, the proportion of the metal compound in the outermost layer of the phenolic resin foam is preferably greater than the proportion of the metal compound in the central layer. By satisfying this condition, the metal compound is efficiently distributed in the thickness direction of the phenolic resin foam, which makes it easier to maintain both the alkali resistance and excellent heat insulating performance of the phenolic resin foam, resulting in a greater effect. The value obtained by dividing the proportion of the metal compound in the outermost layer of the phenolic resin foam by the proportion of the metal compound in the central layer is preferably greater than 1.00, more preferably 1.10 or more, even more preferably 1.30 or more, particularly preferably 1.60 or more, and most preferably 1.70 or more.

[0018] In the phenolic resin foam of this embodiment, the average cell diameter of a cross section of the phenolic resin foam taken 5 mm from the outermost layer (after removing the facing material, if any) in the thickness direction is in the range of 50 to 120 μm, preferably 50 to 110 μm, more preferably 70 to 110 μm, even more preferably 70 to 100 μm, and most preferably 80 to 100 μm. If the average cell diameter at this position is within this range, the metal compound content in the phenolic resin foam on the surface side of this position can be increased accordingly. Therefore, it has been found that the surface side of the phenolic resin foam can exhibit alkali resistance. Note that if the average cell diameter is less than 50 μm, the density of the outermost layer becomes too high, which may cause the foamable phenolic resin composition to easily seep out from the surface of the facing material, potentially contaminating the equipment used to mold the foam. Also, if the average cell diameter is greater than 120 μm, the proportion of metal compounds in the outermost layer may decrease, potentially resulting in a loss of alkali resistance. Therefore, it is not preferable for the average bubble diameter to be greater than 120 μm.

[0019] The closed cell content of the phenolic resin foam in this embodiment is 80% or more, preferably 85% or more, more preferably 90% or more, and most preferably 95% or more. If the closed cell content is too low, the foaming agent encapsulated in the cells is more likely to be replaced with air, which tends to increase the thermal conductivity, accelerate the rate of deterioration of the thermal conductivity over a long period of time, and reduce the compressive strength. The method for measuring the closed cell content will be specifically explained in the Examples below.

[0020] The density of the phenolic resin foam in this embodiment is 20 kg / m 3 ~80kg / m 3 and 25 kg / m 3 ~55kg / m 3 is preferred, and 27 kg / m 3 ~45kg / m 3 is more preferred, and most preferably 27 kg / m 3 ~40kg / m 3 The density is 20 kg / m 3If the density is lower than 80 kg / m, the strength is low and the foam is easily damaged during transportation or application. Also, if the density is low, the cell membrane tends to be thin. If the cell membrane is thin, the blowing agent in the foam is easily replaced with air, and furthermore, the metal compound particles may make the cell membrane even more prone to breakage, making it difficult to obtain a high closed cell ratio. Also, if the density is lower than 80 kg / m, the foam is easily damaged. 3 If the density is higher, the thermal conductivity of the solid components, such as the phenolic resin, increases, which tends to reduce the heat insulating performance. A method for measuring the density of the phenolic resin foam will be specifically described in the examples below.

[0021] The average particle size of the metal compound in this embodiment is preferably 0.1 to 500 μm, more preferably 0.1 to 300 μm, even more preferably 1 to 200 μm, and most preferably 1 to 100 μm. When the average particle size is small, particles tend to aggregate, making it difficult to improve dispersibility. This increases the viscosity of the phenolic resin raw material, making it difficult to uniformly mix the metal compound into the resin. This may result in poor dispersibility of the metal compound. Furthermore, when the particle size is large, the area ratio of the outermost layer becomes more uneven compared to when the particle size is small, even with the same amount added. This large unevenness results in a localized presence of a large amount of metal compound, making it difficult to fully demonstrate alkali resistance. The method for measuring the average particle size of the metal compound is specifically explained in the examples described below.

[0022] The thermal conductivity of the phenolic resin foam of this embodiment, measured at 23°C, is preferably 0.0260 W / (m·K) or less, more preferably 0.0250 W / (m·K) or less, even more preferably 0.0230 W / (m·K) or less, particularly preferably 0.0210 W / (m·K), and most preferably 0.0200 W / (m·K). The lower limit of the thermal conductivity of the phenolic resin foam measured at 23°C is not particularly limited, but is typically about 0.0150 W / (m·K). The method for measuring thermal conductivity will be specifically described in the examples below.

[0023] The alkali resistance of the phenolic resin foam of this embodiment can be evaluated by using the tensile strength of the foam before and after the alkali-accelerated test described below as indicators. The tensile strength retention rate of the phenolic resin foam of this embodiment after the alkali-accelerated test is preferably 30% or more, more preferably 50% or more, and even more preferably 70% or more. If the tensile strength retention rate is less than 30%, sufficient alkali resistance cannot be imparted, and when used in a wet external insulation construction method, the adhesive strength between the mortar and the phenolic resin foam gradually decreases. Because the reduced adhesive strength may cause the mortar to peel off from the phenolic resin foam, the tensile strength retention rate is preferably 30% or more.

[0024] The phenolic resin foam of this embodiment can be obtained by foaming and curing, on a surface material, a "phenolic resin raw material" containing a phenolic resin, a "foamable phenolic resin composition" containing a metal compound, a surfactant, a phenolic resin curing catalyst, and a foaming agent.

[0025] Phenolic resin raw materials contain a phenolic resin as a main component, water, and possibly other components. Phenolic resin raw materials immediately after synthesis typically contain excess water. Therefore, the phenolic resin raw materials must be dehydrated to a predetermined moisture content before use in preparing a foamable phenolic resin composition. The moisture content of the phenolic resin raw materials is preferably 1 to 20 mass%, more preferably 1 to 13 mass%, even more preferably 2 to 10 mass%, particularly preferably 3 to 10 mass%, and most preferably 3 to 8.5 mass%, based on the mass of the phenolic resin raw materials. If the moisture content of the phenolic resin raw materials is less than 1 mass%, the viscosity of the phenolic resin raw materials becomes too high, resulting in high pressure in the equipment and increased risk of poor delivery. Furthermore, if the moisture content of the phenolic resin raw materials is higher than 20 mass%, the viscosity of the foamable phenolic resin composition decreases, reducing the closed cell content of the phenolic resin foam. Furthermore, the residual moisture content after foaming and curing increases, making it difficult for the phenolic resin foam to form closed cells, resulting in reduced thermal insulation. Furthermore, dissipating the residual moisture by heating during molding of the phenolic resin foam requires significant energy and time.

[0026] The phenolic resin in this embodiment is typically a condensation polymer of phenol and formaldehyde, and can be obtained, for example, by polymerizing phenol and formaldehyde as raw materials by heating them in the temperature range of 40 to 100°C in the presence of an alkali catalyst.

[0027] The amount of the metal compound added is preferably 15 parts by mass or less, more preferably 0.5 to 15 parts by mass, even more preferably 1 to 15 parts by mass, and most preferably 3 to 15 parts by mass, per 100 parts by mass of the phenolic resin (phenolic resin raw material). If the amount of the metal compound added is less than 0.5 parts by mass, the content of the metal compound in the phenolic resin foam will be low, and the effect of the addition will not be sufficient. Therefore, an amount of the metal compound added less than 0.5 parts by mass is not preferred. On the other hand, if the amount of the metal compound added is more than 15 parts by mass, the viscosity of the foamable phenolic resin composition after the addition of the metal compound will be too high, which will likely result in poor liquid delivery. Therefore, an amount of the metal compound added more than 15 parts by mass is not preferred. Furthermore, if the viscosity becomes too high, it will be difficult to achieve the expansion ratio required for the phenolic resin foam, which may deteriorate the closed cell ratio and even the thermal conductivity of the resulting phenolic resin foam.

[0028] Surfactants commonly used in the production of phenolic resin foams can be used, with nonionic surfactants being particularly effective. The surfactant preferably contains at least one compound selected from the group consisting of polyoxyalkylene (alkylene oxide), which is a copolymer of ethylene oxide and propylene oxide; condensates of alkylene oxide and castor oil; condensates of alkylene oxide and alkylphenols such as nonylphenol and dodecylphenol; polyoxyethylene alkyl ethers having 14 to 22 carbon atoms in the alkyl ether moiety; fatty acid esters such as polyoxyethylene fatty acid esters; silicone compounds such as polydimethylsiloxane; and polyalcohols. These compounds may be used alone or in combination of two or more. The amount of surfactant is not particularly limited, but is preferably 0.3 to 10 parts by mass per 100 parts by mass of the phenolic resin (or phenolic resin raw material).

[0029] The curing catalyst may be any acidic curing catalyst capable of curing phenolic resins, but an acid anhydride curing catalyst is preferred. Examples of the acid anhydride curing catalyst include phosphoric anhydride and arylsulfonic anhydride. Examples of arylsulfonic anhydrides include toluenesulfonic acid, xylenesulfonic acid, phenolsulfonic acid, substituted phenolsulfonic acid, xylenolsulfonic acid, substituted xylenolsulfonic acid, dodecylbenzenesulfonic acid, benzenesulfonic acid, and naphthalenesulfonic acid. These may be used alone or in combination. Resorcinol, cresol, saligenin (o-hydroxybenzyl alcohol), p-methylolphenol, and the like may also be added as curing aids. These curing catalysts may also be diluted with a solvent such as ethylene glycol or diethylene glycol. The amount of the curing catalyst is not particularly limited, but is preferably 3 to 30 parts by mass per 100 parts by mass of the combined amount of the phenolic resin (or phenolic resin raw material) and surfactant.

[0030] In this embodiment, the blowing agent may include one or more selected from chlorinated and non-chlorinated hydrofluoroolefins, hydrocarbons, and halogenated hydrocarbons.

[0031] Examples of chlorinated hydrofluoroolefins include 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd, for example, E-isomer (HCFO-1233zd(E)), manufactured by Honeywell Japan Co., Ltd., product name: Solstice (trademark) LBA), 1,1,2-trichloro-3,3,3-trifluoropropene (HCFO-1213xa), 1,2-dichloro-3,3,3-trifluoropropene (HCFO-1223xd), 1,1-dichloro-3,3, 3-Trifluoropropene (HCFO-1223za), 1-chloro-1,3,3,3-tetrafluoropropene (HCFO-1224zb), 2,3,3-trichloro-3-fluoropropene (HCFO-1231xf), 2,3-dichloro-3,3-difluoropropene (HCFO-1232xf), 2-chloro-1,1,3-trifluoropropene (HCFO-1233xc), 2-chloro-1,3,3-trifluoropropene (HCFO-1233xe), 2-chloro 1-chloro-3,3,3-trifluoropropene (HCFO-1233xf), 1-chloro-1,2,3-trifluoropropene (HCFO-1233yb), 3-chloro-1,1,3-trifluoropropene (HCFO-1233yc), 1-chloro-2,3,3-trifluoropropene (HCFO-1233yd), 3-chloro-1,2,3-trifluoropropene (HCFO-1233ye), 3-chloro-2,3,3-trifluoropropene (HCFO-1233yf), 1 1-chloro-1,3,3-trifluoropropene (HCFO-1233zb), 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd), 1-chloro-2,3,3,3-tetrafluoropropene (HCFO-1224yd, for example, Z-form (HCFO-1224yd(Z)), manufactured by AGC Inc., product name: AMOLEA (trademark) 1224yd), and the like, and these configurational isomers, i.e., E-form or Z-form, or a mixture thereof, may be used.

[0032] Examples of non-chlorinated hydrofluoroolefins include 1,3,3,3-tetrafluoroprop-1-ene (HFO-1234ze, for example, E-isomer (HFO-1234ze(E)), manufactured by Honeywell Japan Co., Ltd., product name: Solstice™ ze), 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz, for example, Z-isomer (HFO-1336mzz(Z)), manufactured by Chemours Inc., Opteon™ 1100), 2,3,3,3 1,1,3,3,3-tetrafluoro-1-propene (HFO-1234yf), 1,1,3,3,3-pentafluoropropene (HFO-1225zc), 1,3,3,3-tetrafluoropropene (HFO-1234ze), 3,3,3-trifluoropropene (HFO-1243zf), 1,1,1,4,4,5,5,5-octafluoro-2-pentene (HFO-1438mzz), and the like are examples of such configurational isomers, i.e., E- and Z-isomers, which may be used singly or in combination.

[0033] Examples of hydrocarbons that can be used as blowing agents include cyclic or chain alkanes, alkenes, and alkynes having 3 to 7 carbon atoms. Specifically, compounds such as normal butane, isobutane, cyclobutane, normal pentane, isopentane, cyclopentane, neopentane, normal hexane, isohexane, 2,2-dimethylbutane, 2,3-dimethylbutane, and cyclohexane can be used as blowing agents. Among these, compounds selected from pentanes such as normal pentane, isopentane, cyclopentane, and neopentane, and butanes such as normal butane, isobutane, and cyclobutane are preferred. While the halogenated hydrocarbon is not particularly limited, from the viewpoints of low thermal conductivity, low ozone depletion potential and global warming potential, and boiling point, halogenated hydrocarbons containing at least one hydrogen atom, halogenated hydrocarbons containing no two or more halogen atoms, or halogenated hydrocarbons containing no fluorine atoms are preferred, with isopropyl chloride being more preferred. These blowing agents may be used alone or in combination of two or more.

[0034] The amount of foaming agent added to the phenolic resin foam of this embodiment is preferably 3.0 to 25.0 parts by mass, more preferably 5.0 to 22.5 parts by mass, even more preferably 6.5 to 22.5 parts by mass, and most preferably 7.5 to 21.5 parts by mass, relative to 100 parts by mass of the total amount of the phenolic resin (or phenolic resin raw material) and surfactant. If the amount of foaming agent is less than 3.0 parts by mass, it becomes very difficult to obtain the required expansion ratio, and a high-density foam tends to be formed. If the amount of foaming agent exceeds 25.0 parts by mass, the plasticizing effect of the foaming agent reduces the viscosity of the foamable phenolic resin composition, and excessive foaming occurs, which tends to break the cells of the foam and reduce the closed cell ratio. A decrease in the closed cell ratio tends to reduce physical properties such as long-term insulation performance and compressive strength. By keeping the amount of foaming agent added relative to the total amount of the phenolic resin (or phenolic resin raw material) and surfactant within the above numerical range, a foaming pressure of 20 to 80 kg / m can be obtained. 3 The phenolic foam can be formed having a density of

[0035] In addition to the components described above, the foamable phenolic resin composition of this embodiment may contain additives. When urea is added, as is commonly known, urea may be added directly to the reaction solution during or near the end of the phenolic resin reaction, or urea that has been methylolated in advance with an alkali catalyst may be mixed with the phenolic resin. Examples of additives other than urea include phthalate esters, which are commonly used as plasticizers, and glycols such as ethylene glycol and diethylene glycol. Aliphatic hydrocarbons, high-boiling alicyclic hydrocarbons, or mixtures thereof may also be used as additives. The content of the additive is preferably 0.5 to 20 parts by mass per 100 parts by mass of the phenolic resin (or phenolic resin raw material). Adding too much of these additives may reduce the viscosity of the foamable phenolic resin composition, potentially causing cell collapse during foaming and curing. On the other hand, adding too little additive will not achieve the desired effect. Therefore, the content of the additive is more preferably 1.0 to 10 parts by mass.

[0036] In this embodiment, the following flame retardants may be added to the foamable phenolic resin composition as needed. The flame retardant may be selected from, for example, bromine compounds such as tetrabromobisphenol A and decabromodiphenyl ether, phosphorus or phosphorus compounds such as aromatic phosphate esters, aromatic condensed phosphate esters, halogenated phosphate esters, and red phosphorus, antimony compounds such as ammonium polyphosphate, antimony trioxide and antimony pentoxide, metal hydroxides such as aluminum hydroxide and magnesium hydroxide, and carbonates such as calcium carbonate and sodium carbonate.

[0037] A foamable phenolic resin composition can be obtained by mixing the above-mentioned phenolic resin raw material, metal compound, curing catalyst, foaming agent, and surfactant in the above-mentioned ratios.

[0038] The phenolic resin foam can be obtained, for example, by a continuous production method including a mixing step of multiple raw materials, a dispensing step of continuously dispensing a foamable phenolic resin composition onto a traveling facing material, a top-surface-coating step of covering the top surface opposite the surface where the dispensed foamable phenolic resin composition contacts the facing material with a facing material, and a foaming and heat-curing step, as described below. In another embodiment, the foamable phenolic resin foam can also be obtained by a batch production method in which the foamable phenolic resin composition described above is poured into a mold whose inside is coated with a facing material and a mold release agent, and foamed and heat-cured. The phenolic resin foam obtained by the batch production method can also be sliced ​​as needed.

[0039] The facing material sandwiching the phenolic resin foam is a sheet-like substrate, preferably flexible to prevent breakage during production. Flexible facing materials include synthetic fiber nonwoven fabrics, synthetic fiber woven fabrics, glass fiber paper, glass fiber woven fabrics, glass fiber nonwoven fabrics, glass fiber blended paper, paper, metal film, or combinations thereof. These facing materials may contain a flame retardant to impart flame retardancy. Flame retardants may be selected from, for example, bromine compounds such as tetrabromobisphenol A and decabromodiphenyl ether; phosphorus or phosphorus compounds such as aromatic phosphate esters, aromatic condensed phosphate esters, halogenated phosphate esters, and red phosphorus; antimony compounds such as ammonium polyphosphate, antimony trioxide, and antimony pentoxide; metal hydroxides such as aluminum hydroxide and magnesium hydroxide; and carbonates such as calcium carbonate and sodium carbonate. These flame retardants may be kneaded into the facing material fibers or added to binders such as acrylic, polyvinyl alcohol, vinyl acetate, epoxy, and unsaturated polyester. The surface of the facing material can also be treated with a water repellent or asphalt-based waterproofing agent such as a fluororesin-based, silicone resin-based, wax emulsion-based, paraffin-based, or acrylic resin / paraffin wax-based combination. These water repellents and waterproofing agents can be used alone or applied to the facing material together with the flame retardant.

[0040] It is preferable that the face material has high gas permeability. Suitable face materials include synthetic fiber nonwoven fabric, glass fiber paper, glass fiber nonwoven fabric, paper, and pre-punched metal film. Among these face materials, those with an oxygen permeability of 4.5 cm as measured in accordance with ASTM D3985-95 are suitable. 3 / (24h·m 2) or more is particularly preferred. When a facing material with low gas permeability is used, the moisture generated when the phenolic resin hardens cannot be sufficiently dispersed from within the foam, and the moisture remains in the foam, which tends to result in the formation of a foam with a low closed cell ratio and many voids. As a result, it can be relatively difficult to maintain good heat insulating performance over a long period of time. In view of the seepage of the foamable phenolic resin composition into the facing material during foaming and the adhesiveness between the foamable phenolic resin composition and the facing material, when a synthetic fiber nonwoven fabric is used for the facing material, the basis weight thereof is preferably 15 to 200 g / m 2 , more preferably 15 to 150 g / m 2 , and more preferably 15 to 100 g / m 2 , particularly preferably 15 to 80 g / m 2 , and most preferably 15 to 60 g / m 2 When a glass fiber nonwoven fabric is used, the weight per unit area is preferably 30 to 600 g / m 2 , more preferably 30 to 500 g / m 2 , and more preferably 30 to 400 g / m 2 , particularly preferably 30 to 350 g / m 2 , and most preferably 30 to 300 g / m 2 is.

[0041] The method for producing a phenolic resin foam of this embodiment includes a mixing step of a plurality of raw materials, a discharging step, a top surface material coating step, and a foaming and curing step.

[0042] In the mixing step, the metal compound is mixed with the phenolic resin raw material using a mixer. In order to improve the kneadability of the metal compound and the phenolic resin and to obtain a phenolic resin foam more efficiently and stably, the mixing step preferably includes a step of pre-kneading the metal compound and the phenolic resin before adding the blowing agent and the curing catalyst to obtain a metal compound-added phenolic resin composition.

[0043] The method for adding the metal compound to the phenolic resin or phenolic resin composition and kneading them is not particularly limited, and mixing may be performed using a hand mixer, a pin mixer, or the like, or a twin-screw extruder, a kneader, or the like.

[0044] In the discharging step, a surfactant, a curing catalyst, a foaming agent, etc. are mixed uniformly with the mixture of the phenolic resin and the metal compound in a mixer, and then the mixture is discharged.

[0045] To achieve this technology, it is important to manufacture the phenolic resin foam laminate by the following manufacturing method: a mixing step (a) of mixing a foamable phenolic resin composition containing a phenolic resin, a surfactant, a foaming agent, an acidic curing agent, and a metal compound using a mixer, a discharging step (b) of distributing and discharging the mixed foamable phenolic resin composition onto a lower surface material using 9 to 60 nozzles, a pre-molding step (c) of foaming and curing the foamable phenolic resin composition dispensed onto the lower surface material to obtain a phenolic resin foam laminate having face materials disposed on at least the upper and lower surfaces of the phenolic resin foam, and a main molding step (d) of accelerating foaming and curing and molding, wherein the average temperature of the center of the foamable phenolic resin composition dispensed from the dispensing nozzles when the lower surface material and the foamable phenolic resin composition come into contact in the discharging step (b) is 40°C to 55°C, and the ambient temperature in the pre-molding step (c) is 60°C to 80°C, and the residence time is 5 minutes to 20 minutes. Preferably, the average temperature at the center of the foamable phenolic resin composition discharged from the dispensing nozzle is 40°C or higher and 53°C or lower, the ambient temperature in the pre-molding step (c) is 70°C or higher and 80°C or lower, and the residence time is 12 minutes or higher and 20 minutes or lower. The above-mentioned upper surface material covering step is included in the pre-molding step, and the foaming and curing step are included in the pre-molding step and the main molding step.

[0046] By adjusting the average temperature of the center of the foamable phenolic resin composition discharged from the dispensing nozzle when the lower surface material and the foamable phenolic resin composition come into contact in the discharge step (b) to 40°C or higher and 53°C or lower, only the foaming agent near the surface layer of the foamable phenolic resin composition immediately after discharge becomes more likely to volatilize, and the bubble diameter in the surface layer becomes smaller, making it possible to distribute a large amount of metal compound unevenly in the surface layer.As a result, it is possible to contain the metal compound in the surface layer even with a small amount of metal compound added, and it has been found that sufficient alkali resistance can be exhibited.

[0047] If the average temperature at the center of the extruded foamable phenolic resin composition is less than 40°C, the timing of volatilization of the blowing agent near the surface of the extruded foamable phenolic resin composition from each nozzle will be delayed, resulting in larger bubble diameters in the surface layer and insufficient distribution of the metal compound in the surface layer, which may result in an insufficient amount of metal compound being unevenly distributed, resulting in an inability to exhibit alkali resistance. Furthermore, if the average temperature at the center of the extruded foamable phenolic resin composition exceeds 53°C, the blowing agent contained in the foamable phenolic resin composition will volatilize too much, and foaming will be accelerated more than curing, which may result in a decrease in the closed cell ratio, which is undesirable. The average temperature at the center of the extruded foamable phenolic resin composition can be optimized by adjusting the temperature and flow rate of the water in the mixing head distribution section where the various components are mixed, as well as the rotation speed. In addition, the average temperature at the center of the foamable phenolic resin composition immediately after being discharged from the mixer was determined by measuring the temperature at the center of the foamable phenolic resin material discharged from any 10 nozzles, and then averaging the temperatures at the center of the foamable phenolic resin composition discharged from 8 nozzles, excluding the highest and lowest temperatures.

[0048] In the preforming step (c), the ambient temperature during preforming is preferably 60° C. or higher and 80° C. or lower, and the residence time is preferably 5 minutes or higher and 20 minutes or lower. These ranges of ambient temperature and residence time are preferable because they promote curing of the surface layer while volatilizing the blowing agent contained in the vicinity of the surface layer of the foamable phenolic resin immediately after discharge, thereby increasing the proportion of metal compounds in the outermost layer of the resulting phenolic resin foam and achieving both a high closed cell ratio and fine cell diameters in the phenolic resin foam.

[0049] More specifically, in the pre-molding step (c), the atmospheric temperature during pre-molding is set relatively high (60°C or higher and 80°C or lower) and the residence time is set relatively long (5 minutes or higher and 20 minutes or lower), thereby accelerating the volatilization of the foaming agent near the surface layer of the foamable phenolic resin composition while quickly curing the surface layer of the foamable phenolic resin composition, and thereby making it possible to obtain the desired phenolic resin foam.

[0050] For heating in the main molding step (d) following the pre-molding step (c), for example, the following first oven and second oven can be used.

[0051] In the first oven, the foamable phenolic resin composition is foamed and cured in an atmosphere of 60 to 110°C for a residence time of 10 to 60 minutes. For example, an endless steel belt type double conveyor or a slat type double conveyor is used as the first oven. In the first oven, the uncured foam is cured while being formed into a plate, thereby obtaining a partially cured foam. The temperature inside the first oven does not need to be uniform throughout, and multiple temperature zones may be provided.

[0052] The second oven can accelerate curing with a residence time of 60 to 240 minutes in an atmosphere of 70 to 120°C. The second oven is preferably used to post-cure the phenolic resin foam partially cured in the first oven. The partially cured foam boards may be stacked at regular intervals using spacers or trays. If the temperature in the second oven is too high, the pressure of the blowing agent inside the foam cells may become too high, potentially causing cell collapse. Conversely, if the temperature in the second oven is too low, it may take too long to volatilize the excess moisture in the foam while promoting the reaction of the phenolic resin. Therefore, the preferred ambient temperature in the second oven is 80 to 110°C.

[0053] The manufacturing method for obtaining the phenolic resin foam of this embodiment is not limited to the above-mentioned method.

[0054] As described above, the manufacturing method according to this embodiment can provide a phenolic resin foam having excellent alkali resistance and excellent heat insulating performance. [Example]

[0055] The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited to the following examples.

[0056] The following items were measured and evaluated for the composition, structure and properties of the phenolic resin and phenolic resin foam in the examples and comparative examples.

[0057] (closed bubble rate) The closed cell content of the phenolic resin foam was measured by the following method in accordance with ASTM-D-2856-94(1998) Method A. That is, a cube specimen of approximately 25 mm square was cut out from the center in the thickness direction of the phenolic resin foam. When a specimen of uniform thickness of 25 mm could not be obtained due to the thinness of the foam, the surface of the cut cube specimen of approximately 25 mm square was sliced ​​in increments of approximately 1 mm to prepare a specimen of uniform thickness. The length of each side was measured with a vernier caliper, and the apparent volume (V1: cm 3 ) and the mass of the specimen (W: significant figures 4, g). Subsequently, a dry automatic density meter (Shimadzu Corporation, trade name "AccuPyc II1340") was used to measure the closed space volume (V2: cm2) of the specimen in accordance with the method described in Method A of ASTM-D-2856. 3 The surface area (A: cm) of the specimen was calculated from the length of each side already measured. 3 The open volume (VA: cm) of the cut bubbles on the surface of the specimen was calculated by substituting the determined t and A into the formula: VA = (A × t) / 1.14. 3 ) was calculated. The density of the solid phenolic resin was set to 1.3 g / cm 3 The volume of the solid portion that constitutes the bubble wall contained in the specimen (VS: cm 3 ) was calculated using the formula: VS = specimen mass (W) / 1.3. The closed cell ratio was calculated using the following formula (1). Closed cell ratio (%)=[(V2-VS) / (V1-VA-VS)]×100 (1) The closed cell ratio was measured for six foams obtained under the same manufacturing conditions, and the average value was used as the representative value for foams obtained under those manufacturing conditions.

[0058] (Measuring the average bubble diameter) The average cell diameter in the central layer and 5 mm below the outermost layer of a phenolic resin foam can be determined using the following method. The average cell diameter of a cross section cut parallel to the outermost layer at a position 5 mm below the outermost layer was measured by cutting a section 5 mm below the outermost layer on one side of the phenolic resin foam parallel to the front and back surfaces, and then measuring only the surface of the phenolic resin foam that did not include the outermost layer. Specifically, a photograph of the cut surface of the specimen was taken at a magnification of 50x. Four lines, each with a length equivalent to 2,000 μm in the actual cross section of the foam, were drawn on the photograph, avoiding voids. The number of cells crossing each line was counted, and the cell diameter obtained by dividing 2,000 μm by the number of cells was determined. Similarly, a section 5 mm below the outermost layer on the opposite side was cut parallel to the front and back surfaces, and the cell diameter was determined in the same manner as above. The average value of the obtained eight cell diameters was calculated and used as the average cell diameter (t: cm) of the phenolic resin foam. Note that the term "void" refers to a cell having a diameter equivalent to a roughly circular diameter of 1.5 cm or more on the 50x magnified photograph.

[0059] (Foam density) The foam density of the phenolic resin foam was measured according to JIS-K-7222. A 20cm square board was cut from the obtained phenolic resin foam and used as a sample. Surface materials such as facings and siding were removed from this sample, and the mass and apparent volume of the remaining foam sample were measured, and the foam density was calculated from these values.

[0060] (Calculation of the proportion of metal compounds in the foam) The proportion of metal compounds present in the foam was determined by mapping the metal elements of the metal compounds using the μ-XRF method, and analyzing the resulting mapping image to determine the area proportion of the metal elements, which was then taken as the proportion of the metal compounds present.

[0061] If a phenolic resin foam surface was attached, the surface was removed and three randomly selected scan points were selected on the outermost layer in the thickness direction. The sample was measured using a μ-XRF (EDAX OrbisPC, AMETEC) with a Rh X-ray tube, 50 kV tube voltage, auto CPS tube current, a scan area of ​​20.08 mm x 12.4 mm, a 78 μm X-axis measurement interval, a 62 μm Y-axis measurement interval, a 30 μm X-ray beam diameter, and a 100 msec measurement time per point. The intensity mapping images of metal elements obtained from the measurements were analyzed using ImageJ (NIH) image analysis software. The images were first scanned and converted to grayscale (monochrome). Next, the images were binarized (black background, white metal elements). The moment method was used as the threshold for binarization. The area ratio (%) of the white area was calculated using Analyze Particles, and the average of the three points was calculated. The area ratio of this metal element was taken as the abundance ratio of the metal compound.

[0062] To calculate the area ratio of the central layer of the phenolic resin foam, the central portion of the phenolic resin foam was sliced ​​in the thickness direction to obtain a cross section, and measurements were taken at three randomly selected points. The average value of the three points was calculated as the proportion of the metal compound in the central layer.

[0063] (Average particle size) The average particle size of the metal compound was determined under the following conditions. Measurements were taken using a particle size distribution analyzer (Nikkiso Microtrac MT3300EXII-SDC). Water was used as the solvent and the metal compound was added dropwise to achieve an appropriate concentration. Using the transmission method, a laser beam with a wavelength of 780 nm and an output of 3 mW was used as the light source. The shape was aspherical, and the measurement time was 30 seconds, with measurements taken twice. The resulting volume average diameter was taken as the average particle size of the metal compound.

[0064] (thermal conductivity) The initial thermal conductivity of the phenolic resin foam was measured in an environment of 23°C according to JIS A 1412-2:1999 using the following method. First, the phenolic resin foam was cut into 600 mm square pieces. The resulting specimens were placed in an atmosphere of 23±1°C and 50±2% humidity, and the change in mass over time was measured every 24 hours. The specimens were conditioned until the mass change rate over 24 hours was 0.2% by mass or less. The conditioned specimens were then peeled off without damaging the foam, and then placed in a thermal conductivity measuring device placed in the same environment.

[0065] The thermal conductivity was measured using a single specimen and a symmetrical measuring device (manufactured by Eiko Seiki Co., Ltd., product name "HC-074 / 600"). The thermal conductivity in a 23°C environment was measured with the low temperature plate at 13°C and the high temperature plate at 33°C.

[0066] (Alkali resistance test) In this embodiment, the alkali resistance was evaluated by the following method. Specifically, foam samples of any thickness were cut into 50 mm (length) x 50 mm (width) pieces, and the outermost layer of the facing material was removed to prepare the foam. The tensile strength of the specimen at this stage was measured and recorded as the initial tensile strength, Ha (kPa). Mortar (Weber: Thermplus Ultra) and water were mixed in a mass ratio of 1:0.27 and then stirred at 500 rpm for 4 minutes using a Three-One motor (HEIDON BL1200). The mixed mortar was applied to a thickness of 7 mm on the outermost layer of the foam sample, from which the facing material had been removed, and then cured for 7 days at 23°C and 50% RH. After curing, the specimens were left in an environment at 70°C and 95% RH for 14 days, followed by another 7 days at 23°C and 50% RH. The tensile strength of the specimen after the test was measured and recorded as the tensile strength, Hb (kPa), after the alkali resistance test. The strength retention rate of the tensile strength was calculated using the following formula (2): Tensile strength retention rate (%) = 100 × Hb / Ha (2)

[0067] The tensile test was carried out as follows. A stainless steel jig, 50 mm wide, 50 mm long, and 2 mm thick, was attached to both the top and bottom surfaces of the specimen in the thickness direction (on the surface of the applied mortar in the case of specimens with mortar attached) with adhesive (Konishi Bond Quick 5). After leaving it at room temperature for 24 hours, it was attached to a strength testing machine (Shimadzu Corporation, AG-Xplus). The tensile test was carried out at a tensile speed of 3 mm / min, and the maximum load L (N) was calculated. The tensile strength was calculated using the following formula (3). Tensile strength (kPa) = L (N) / surface area of ​​the specimen (m 2 ) (3)

[0068] (Viscosity of phenolic resin or phenolic resin raw material) Using a rotational viscometer (manufactured by Toki Sangyo Co., Ltd., RE-85R model, rotor part 3° × R14), the rotation speed was set so that the torque value was 10% or more, and the viscosity value after stabilizing at 40°C for 3 minutes was taken as the measured value.

[0069] (Synthesis of phenolic resin raw materials) A reactor was charged with 3,500 kg of a 52% by mass aqueous formaldehyde solution and 2,510 kg of 99% by mass phenol. The reaction solution in the reactor was stirred with a propeller-rotating stirrer, and the temperature of the reaction solution was adjusted to 40°C with a temperature controller. Next, a 50% by mass aqueous sodium hydroxide solution was added until the pH of the reaction solution reached 8.7. The reaction solution was heated to 85°C over 1.5 hours, and the Ostwald viscosity reached 30 centistokes (=30 × 10 -6 m 2 When the pH reached 1.0 (pH 7.0 / s, measured at 25°C), the reaction solution was cooled and 400 kg of urea was added. The reaction solution was then cooled to 30°C, and a 50% by weight aqueous solution of paratoluenesulfonic acid monohydrate was added until the pH reached 6.4. The resulting reaction solution was concentrated using a thin-film evaporator to obtain a phenolic resin raw material containing phenolic resin. The resulting phenolic resin raw material had a moisture content of 2.4% by weight and a viscosity of 8,800 mPa·s.

[0070] Example 1 To 100 parts by weight of phenolic resin raw material, 10 parts by weight of calcium sulfate (average particle size 60 μm) as a metal compound was added using a twin-screw extruder (manufactured by Technovel Corporation) to obtain a mixture of phenolic resin raw material and metal compound. To the metal compound-added phenolic resin raw material, 2.0 parts by weight of an ethylene oxide-propylene oxide block copolymer (BASF, "Pluronic F-127") as a surfactant, 6.3 parts by weight of a blowing agent (normal pentane: nP), and 10 parts by weight of a mixture of 80% by weight of xylene sulfonic acid and 20% by weight of diethylene glycol as a catalyst were added and mixed uniformly. After uniform mixing, the resulting foamable phenolic resin composition was distributed using a multi-port distribution pipe and supplied onto a moving underside material. The mixer used was that disclosed in JP 10-225993 A. Specifically, a mixer was used, which had inlets for the phenolic resin composition containing a solid foam nucleating agent and the foaming agent on the upper side, and an inlet for the acidic curing agent on the side near the center of the agitation section where the rotors agitate. The agitation section was connected to a nozzle for discharging the foamable phenolic resin composition. Specifically, the mixer was composed of the mixing section (front stage) up to the acidic curing agent inlet, the mixing section (rear stage) from the acidic curing agent inlet to the agitation end section, and the distribution section from the agitation end section to the nozzle. The distribution section had multiple nozzles at its tip, designed to ensure uniform distribution of the mixed foamable phenolic resin composition. Furthermore, the distribution section had a jacketed structure, allowing for sufficient heat exchange using temperature-controlled water. The temperature-controlled water temperature of the mixing head distribution section was set to 26°C. A thermocouple was installed at the outlet of the multi-port distribution pipe to measure the average temperature at the center of the foamable phenolic resin composition. The rotation speed of the mixing head was set to 600 rpm. The mixture discharged from the mixer was sandwiched between nonwoven fabrics and sent to a preheated oven at 70°C, where it was retained for 12 minutes. The average temperature of the center of the foamable phenolic resin product immediately after being discharged from the mixer was 45°C. It was then sent to a first oven at 88°C, where it was cured for a retention time of 40 minutes, and then cured in a second oven at 110°C for 2 hours to obtain the phenolic resin foam of Example 1.

[0071] Example 2 The phenolic resin foam of Example 2 was obtained in the same manner as in Example 1, except that the rotation speed of the mixing head was changed to 350 rpm so that the average temperature of the center of the foamable phenolic resin material immediately after being discharged from the mixer was 40°C.

[0072] Example 3 The phenolic resin foam of Example 3 was obtained in the same manner as in Example 1, except that the rotation speed of the mixing head was changed to 950 rpm, so that the average temperature of the center of the foamable phenolic resin material immediately after being discharged from the mixer was 53°C.

[0073] Example 4 A phenolic resin foam of Example 4 was obtained in the same manner as in Example 2, except that the amount of calcium sulfate added was changed to 0.8 parts by mass.

[0074] Example 5 A phenolic resin foam of Example 5 was obtained in the same manner as in Example 3, except that the amount of calcium sulfate added was 15 parts by mass.

[0075] Example 6 A phenolic resin foam of Example 6 was obtained in the same manner as in Example 5, except that the oven temperature in the preforming step was 80°C and the residence time was 20 minutes.

[0076] Example 7 A phenolic resin foam of Example 7 was obtained in the same manner as in Example 1, except that the metal compound was changed to magnesium sulfate.

[0077] Example 8 A phenolic resin foam of Example 8 was obtained in the same manner as in Example 1, except that the metal compound was changed to iron (II) sulfate heptahydrate.

[0078] Example 9 A phenolic resin foam of Example 9 was obtained in the same manner as in Example 1, except that the metal compound was changed to potassium sulfate.

[0079] Example 10 A phenolic resin foam of Example 10 was obtained in the same manner as in Example 6, except that the metal compound was changed to calcium carbonate and the amount added was changed to 1 part by mass.

[0080] (Comparative Example 1) A phenolic resin foam of Comparative Example 1 was obtained in the same manner as in Example 1, except that calcium sulfate, a metal compound, was not added.

[0081] (Comparative Example 2) The phenolic resin foam of Comparative Example 2 was obtained in the same manner as in Example 1, except that the amount of calcium sulfate, a metal compound, added was set to 0.8 parts by mass, the rotation speed of the mixing head was set to 350 rpm, and the temperature of the temperature-controlled water in the mixing head distribution section was changed to 22°C, thereby setting the average temperature of the center of the foamable phenolic resin material immediately after being discharged from the mixer to 38°C.

[0082] (Comparative Example 3) The phenolic resin foam of Comparative Example 3 was obtained in the same manner as in Example 6, except that the rotation speed of the mixing head was changed to 950 rpm and the temperature of the temperature-controlled water in the mixing head distribution section was changed to 28°C, so that the average temperature of the center of the foamable phenolic resin material immediately after being discharged from the mixer was 57°C.

[0083] The above-mentioned measurements and evaluation tests were carried out on Examples 1 to 10 and Comparative Examples 1 to 3. The measurement results and evaluation results are shown in Tables 1 and 2. [Table 1]

[0084] [Table 2]

Claims

[Claim 1] The following (1), (2), and (3) are satisfied, and the closed cell ratio is 80% or more and the foam density is 20 to 80 kg / m ３ Phenolic resin foam. (1) The content of the metal compound in the outermost layer of the phenolic resin foam is 0.5 to 25.0%. (2) The content of the metal compound in the central layer of the phenolic resin foam is 0.5 to 15.0%. (3) The average cell diameter of the cross section of the phenolic resin foam cut parallel to the outermost layer at a position 5 mm from the outermost layer in the thickness direction is 50 to 120 μm.

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