JP7140492B2 - Phenolic resin foam and method for producing the same - Google Patents

Description

The present invention relates to phenolic resin foams.

Phenolic resin foams are used in various fields as heat insulating materials because they are excellent in flame retardancy, heat resistance, chemical resistance, corrosion resistance, and the like. For example, in the construction field, phenolic resin foams are used as synthetic resin building materials, particularly as heat insulating materials for wallboards.
Phenolic resin foams are usually produced by foaming and curing an expandable phenolic resin composition containing a phenolic resin, a blowing agent, an acid catalyst (curing agent) and the like. The phenolic resin foam thus produced has closed cells, and the closed cells contain gas generated from the foaming agent.
It has been proposed to use a mixture of 2-chloropropane, a chlorinated aliphatic hydrocarbon, and isopentane, an aliphatic hydrocarbon, as a blowing agent for phenolic resin foams. A phenolic resin foam using such a mixture as a foaming agent is said to be essentially free of cell defects and exhibit stable and low thermal conductivity (see Patent Document 1).

Japanese Patent No. 4939784

According to the findings of the present inventors, when constructing a phenolic resin foam, fine shavings generated when cutting the phenolic resin foam tend to adhere to the phenolic resin foam, making it difficult to clean in some cases.
An object of the present invention is to provide a phenolic resin foam to which chips are less likely to adhere.

The present inventors paid attention to the surface resistivity of the phenolic resin foam. If the surface resistivity is reduced, it becomes less likely to be charged with static electricity, and the adhesion of chips can be suppressed.

The present invention has the following aspects.
<1> Contains a phenolic resin and a halogenated unsaturated hydrocarbon, has a density of 15 to 50 kg/m ³ , an average cell diameter of 200 μm or less, a closed cell rate of 80% or more, and a surface resistivity of 1×10 ¹² . A phenolic resin foam that is Ω/□ or less.
<2> The phenolic resin foam of <1>, which has an equilibrium water content of 3 to 10% by mass.

According to the present invention, it is possible to obtain a phenolic resin foam to which chips are less likely to adhere.

The phenolic resin foams of the present invention comprise a cured phenolic resin and a blowing agent comprising a halogenated unsaturated hydrocarbon.
The phenolic resin foam of the present invention can be obtained by a method comprising foaming and curing a foamable phenolic resin composition comprising a phenolic resin, a blowing agent comprising a halogenated unsaturated hydrocarbon, and an acid catalyst. .

<Phenolic resin>
As the phenolic resin, a resol type one is preferable.
A resol-type phenolic resin is a phenolic resin obtained by reacting a phenolic compound and an aldehyde in the presence of an alkali catalyst.
Phenol compounds include phenol, cresol, xylenol, paraalkylphenol, paraphenylphenol, resorcinol and modified products thereof. Aldehydes include formaldehyde, paraformaldehyde, furfural, acetaldehyde and the like.
Alkali catalysts include sodium hydroxide, potassium hydroxide, calcium hydroxide, aliphatic amines (trimethylamine, triethylamine, etc.), and the like.
However, the phenol compound, aldehyde and alkali catalyst are not limited to those mentioned above.
The ratio of the phenol compound and the aldehyde used is not particularly limited. Preferably, the molar ratio of phenolic compound to aldehyde is from 1:1 to 1:3, more preferably from 1:1.3 to 1:2.5.

The weight average molecular weight Mw of the phenolic resin determined by gel permeation chromatography is generally 400-3000, preferably 700-2000. If the weight-average molecular weight Mw is less than 400, the closed cell content tends to decrease, which tends to lead to a decrease in compressive strength and a decrease in long-term thermal conductivity performance. Moreover, a foam with many voids and a large average cell diameter is likely to be formed. If the weight-average molecular weight Mw is more than 3000, the viscosities of the phenolic resin raw material and the phenolic resin composition become too high, requiring a large amount of blowing agent to obtain the required expansion ratio. A large amount of blowing agent is not economical.

<Blowing agent>
Blowing agents include halogenated unsaturated hydrocarbons. Halogenated unsaturated hydrocarbons include fluorinated unsaturated hydrocarbons, chlorinated unsaturated hydrocarbons, chlorinated fluorinated unsaturated hydrocarbons, brominated fluorinated unsaturated hydrocarbons, iodinated fluorinated unsaturated hydrocarbons, etc. is mentioned. The halogenated unsaturated hydrocarbon may be one in which all of the hydrogen atoms are substituted with halogen atoms, or one in which some of the hydrogen atoms are substituted with halogen atoms.
As the halogenated unsaturated hydrocarbon, those having fluorine atoms such as fluorinated unsaturated hydrocarbons and chlorinated fluorinated unsaturated hydrocarbons are preferable.
These halogenated unsaturated hydrocarbons may be used singly or in combination of two or more.

Chlorinated fluorinated unsaturated hydrocarbons include those containing chlorine atoms, fluorine atoms and carbon-carbon double bonds in the molecule, such as 1,2-dichloro-1,2-difluoroethene (E and Z isomer), 1-chloro-3,3,3-trifluoropropene (HCFO-1233zd) (E and Z isomers) (for example, HoneyWell, trade name: SOLSTICE LBA), 1-chloro-2, 3,3-trifluoropropene (HCFO-1233yd) (E and Z isomers), 1-chloro-1,3,3-trifluoropropene (HCFO-1233zb) (E and Z isomers), 2-chloro- 1,3,3-trifluoropropene (HCFO-1233xe) (E and Z isomers), 2-chloro-2,2,3-trifluoropropene (HCFO-1233xc), 2-chloro-3,3,3 -trifluoropropene (HCFO-1233xf) (for example, manufactured by SynQuest Laboratories, product number: 1300-7-09), 3-chloro-1,2,3-trifluoropropene (HCFO-1233ye) (E and Z isomers ), 3-chloro-1,1,2-trifluoropropene (HCFO-1233yc), 3,3-dichloro-3-fluoropropene, 1,2-dichloro-3,3,3-trifluoropropene (HFO -1223xd) (E and Z isomers), 2-chloro-1,1,1,4,4,4-hexafluoro-2-butene (E and Z isomers), and 2-chloro-1,1, 1,3,4,4,4-heptafluoro-2-butene (E and Z isomers) and the like.
More preferred are those containing a hydrogen atom, a chlorine atom, a fluorine atom and a carbon-carbon double bond in the molecule (HCFO).

Examples of fluorinated unsaturated hydrocarbons include hydrofluoroolefins (hereinafter also referred to as "HFO") containing hydrogen atoms, fluorine atoms and carbon-carbon double bonds in the molecule. ,3-tetrafluoropropene (HFO-1234yf), 1,3,3,3-tetrafluoropropene (HFO-1234ze) (E and Z isomers), 1,1,1,4,4,4-hexafluoro -2-butene (HFO1336mzz) (E and Z isomers) (for example, manufactured by SynQuest Laboratories, product number: 1300-3-Z6), and those disclosed in JP-T-2009-513812.

The halogenated unsaturated hydrocarbon contained in the foaming agent is advantageous in that it has a low ozone depletion potential (ODP) and a low global warming potential (GWP) and has a low impact on the environment. As the halogenated unsaturated hydrocarbon, a chlorinated fluorinated unsaturated hydrocarbon or a fluorinated unsaturated hydrocarbon is preferred.

The foaming agent preferably further contains a chlorinated saturated hydrocarbon or a saturated hydrocarbon from the viewpoint of lowering production costs.
As the chlorinated saturated hydrocarbon, those having 2 to 5 carbon atoms are preferred. Chlorinated aliphatic hydrocarbons are more preferred. Examples include dichloroethane, propyl chloride, isopropyl chloride, butyl chloride, isobutyl chloride, pentyl chloride, isopentyl chloride and the like.
Among the above, isopropyl chloride (also known as 2-chloropropane) is preferable because of its low ozone layer depletion potential and excellent environmental compatibility.

As the saturated hydrocarbon, those having 3 to 7 carbon atoms are preferred. Examples include butane, isobutane, pentane, isopentane, cyclopentane, hexane, heptane, etc.).

The blowing agent may further contain blowing agents other than the above halogenated unsaturated hydrocarbons, chlorinated saturated hydrocarbons, and saturated hydrocarbons, if desired. Other blowing agents include fluorinated saturated hydrocarbons; low boiling point gases such as nitrogen, argon, carbon dioxide, air; sodium bicarbonate, sodium carbonate, calcium carbonate, magnesium carbonate, azodicarboxylic acid amide, azobisisobutyro Chemical blowing agents such as nitrile, barium azodicarboxylate, N,N'-dinitrosopentamethylenetetramine, p,p'-oxybisbenzenesulfonylhydrazide, trihydrazinotriazine; porous solid materials;

The content of the blowing agent in the phenolic resin foam (or foamable phenolic resin composition) is preferably 1 to 25 parts by mass, more preferably 3 to 15 parts by mass, and 5 to 11 parts by mass per 100 parts by mass of the phenolic resin. Part is more preferred.
The proportion of the halogenated unsaturated hydrocarbon in 100 parts by mass of the foaming agent is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and most preferably 50 parts by mass or more. It may be 100 parts by mass.

When the foaming agent is a mixture of two or more types of foaming agents, the composition (mass ratio) of the foaming agent contained in the foamable phenolic resin composition is different from the composition of the foaming agent contained in the foamed and cured phenolic resin foam. Almost match. The composition of two or more blowing agents contained in the phenolic resin foam can be confirmed, for example, by the following solvent extraction method.
Solvent extraction method:
A standard gas of a halogenated unsaturated hydrocarbon, a halogenated saturated hydrocarbon, or a saturated hydrocarbon is used in advance to determine the retention time under the following measurement conditions with a gas chromatograph-mass spectrometer (GC/MS). Next, 1.6 g of a sample of the phenolic resin foam from which the upper and lower face materials were removed was placed in a crushing glass container, and 80 mL of tetrahydrofuran (THF) was added. After crushing the sample to the extent that it is immersed in the solvent, it is pulverized and extracted with a homogenizer for 1 minute and 30 seconds, the extract is filtered through a membrane filter with a pore size of 0.45 μm, and the filtrate is subjected to GC/MS. The type of hydrocarbon is identified from the retention time and mass spectrum determined in advance. The detection sensitivity of each of the foaming agent components is measured using standard gases, and the composition (mass ratio) is calculated from the detection area and detection sensitivity of each gas component obtained by the GC/MS.
・ GC / MS measurement conditions Column used: DB-5ms (Agilent Technologies) 60 m, inner diameter 0.25 mm, film thickness 1 μm
Column temperature: 40°C (10 minutes) -10°C/min -200°C
Inlet temperature: 200°C
Interface temperature: 230°C
Carrier gas: He 1.0 mL/min Split ratio: 20:1
Measurement method: scanning method m/Z = 11 to 550

<Additive>
(acid catalyst)
The acid catalyst is included in the foamable phenolic resin composition to cure the phenolic resin.
Examples of acid catalysts include organic acids such as benzenesulfonic acid, ethylbenzenesulfonic acid, p-toluenesulfonic acid, xylenesulfonic acid, naphthalenesulfonic acid and phenolsulfonic acid, and inorganic acids such as sulfuric acid and phosphoric acid. These acid catalysts may be used alone or in combination of two or more.
The content of the acid catalyst in the foamable phenol resin composition is preferably 5 to 30 parts by mass, more preferably 8 to 25 parts by mass, even more preferably 10 to 20 parts by mass, per 100 parts by mass of the phenolic resin.

(Surfactant)
The foamable phenolic resin composition may contain a surfactant. A surfactant contributes to miniaturization of the bubble diameter (cell diameter).
Surfactants are not particularly limited, and those known as foam stabilizers and the like can be used. Examples include castor oil alkylene oxide adducts, silicone surfactants, polyoxyethylene sorbitan fatty acid esters, and the like. These surfactants may be used alone or in combination of two or more.
It is preferable to use a surfactant having an HLB (Hydrophilic-Lipophilic Balance) of 8 to 18. When the HLB of the surfactant is within the above range, it is easy to obtain a phenolic resin foam that absorbs less water when the atmospheric humidity increases. HLB of the surfactant is more preferably 10-14. When multiple types of surfactants are mixed and used, the HLB is the weighted average of the HLB of each component.

When the phenolic resin foam contains a surfactant, the content of the surfactant in the foamable phenolic resin composition is preferably 1 to 10 parts by mass, more preferably 2 to 5 parts by mass, per 100 parts by mass of the phenolic resin. preferable. If the content of the surfactant is at least the lower limit of the above range, the cell diameter tends to be uniformly small. .

The surfactant used in the present invention can be detected and quantified in the phenolic resin foam from a relatively low concentration to a high concentration by analysis using the following measurement equipment.

The first measurement device that may be mentioned is the matrix-assisted laser desorption ionization-time-of-flight mass spectrometer (MALDI-TOF/MS). Analysis by this instrument is performed by irradiating a mixture of the matrix and the sample to be measured with a laser beam and ionizing the sample molecules through the matrix for soft ionization. It is characterized by the ability to measure high molecules.

The next measuring instrument to be mentioned is NMR. This device is a measurement device using nuclear magnetic resonance, and can identify the structure of a substance to be measured because the position of the measured peak (chemical shift) varies depending on the chemical environment of the nuclide. Further, since the molar ratio can be quantified from the integrated value of the peak, it is possible to quantify the surfactant used in the present invention using the internal standard method.

In order to analyze the surfactant in the phenolic resin foam, it is first necessary to extract the surfactant from the phenolic resin foam. For example, a phenolic resin foam is cut to a certain size, ground with a pestle and mortar, and made into a fine powder using a Soxhlet extractor. Extract. The extract can be dried and weighed to determine the amount of extract. The dried product is measured by MALDI-TOF/MS. At this time, a sodium iodide/acetone solution can be used as an ionization aid, and a dithranol/chloroform solution can be used as a matrix.
For example, when measuring polyoxyethylene stearyl ether of alkyl group C18 with HLB=17.6, the most frequent peak appears around 2010 and the peak interval is detected at about 44. Based on this detection state, the presence of polyoxyethylene alkyl ether and its amount can be estimated from the height (intensity) of the peak.

Also, using the same dried sample as above, dissolving it in deuterated chloroform solvent, using dimethyl sulfoxide as an internal standard substance in NMR, for example, at 400 MHz, from the peak intensity appearing at 2.6 PPM and 3.6 PPM, Determine the amount of polyoxyethylene alkyl ether in the dried sample. When measuring the above-mentioned polyoxyethylene stearyl ether of alkyl group C18 with HLB = 17.6 from the phenolic resin foam, in the Soxhlet extraction, components other than the surfactant are also extracted, so in a known sample , Using a calibration curve for the added amount of surfactant and the amount of surfactant in the Soxhlet extract, determine the amount in the foam. By measuring in this way, even if the content in the sample is extremely small, the amount of surfactant present in the phenolic resin foam can be measured with high accuracy.

(other ingredients)
Other components that can be added to the foamable phenolic resin composition include those known as additives for phenolic foams, such as urea, plasticizers, fillers, flame retardants (e.g., phosphorus-based flame retardants, etc.), Cross-linking agents, organic solvents, amino group-containing organic compounds, coloring agents, neutralizing agents, and the like can be mentioned.

<Manufacturing method>
A foamable phenolic resin composition can be prepared by mixing the components described above.
The mixing order of each component is not particularly limited. can be supplied to a mixer and stirred to prepare a foamable phenolic resin composition.

The phenolic resin foam of the present invention can be produced by foaming and curing the foamable phenolic resin composition.
The phenolic resin foam can be produced by known methods. For example, a foamable phenol resin composition is heated in a heating furnace to foam and cure (foaming/curing step), and further cured and dried in a dryer (post-curing/drying step) to form a phenol resin foam. A method of manufacture is preferred.

A face material may be provided when the phenolic resin foam is produced by foam molding.
The surface material is not particularly limited, and glass paper, glass fiber woven fabric, glass fiber nonwoven fabric, glass fiber mixed paper, kraft paper, synthetic fiber nonwoven fabric composed of fibers such as polyester, polypropylene, nylon, spunbond nonwoven fabric, At least one selected from aluminum foil-clad nonwoven fabric, aluminum foil-clad kraft paper, metal plate, metal foil, plywood, calcium silicate plate, gypsum board and wood-based cement board is preferable, especially glass fiber mixed paper, Glass fiber non-woven fabrics and synthetic fiber non-woven fabrics are preferred because they are readily available due to their high industrial distribution. Among them, the synthetic fiber nonwoven fabric is preferable because it is easy to handle because it is possible to control the texture and fluffiness of the surface layer of the nonwoven fabric by changing the pattern of heat-sealing points between fibers with an embossing heating roll in manufacturing. In addition, when the face material is a synthetic fiber nonwoven fabric, it is possible to suppress the occurrence of wrinkles due to shrinkage of the face material due to moisture in the expandable phenol resin composition and water generated during condensation of the phenol resin.
The face material may be provided on one side or both sides of the phenol resin foam. When provided on both sides, each face material may be the same or different.
As a method of providing a face material when producing a phenolic resin foam, for example, a face material is placed on a continuously running conveyor belt, a foamable phenol resin composition is discharged onto the face material, and A method of laminating another face material and then passing the laminate through a heating furnace for foam molding can be used. As a result, a phenolic resin foam with face materials is obtained in which the face materials are laminated on both sides of the sheet-like phenolic resin foam.
The face material may be attached to the phenolic resin foam with an adhesive after foam molding.

The basis weight of the face material is not particularly limited, but when using a synthetic fiber nonwoven fabric, the basis weight is preferably 15 g/m ² or more and 200 g/m ² or less, and 15 g/m ² or more and 150 g/m ² or less. more preferably 15 g/m ² or more and 100 g/m ² or less, particularly preferably 20 g/m ² or more and 80 g/m ² or less, and 20 g/m ² or more and 60 g/m ² or less. Most preferably there is.
When glass fiber mixed paper is used, the basis weight is preferably 30 g/m ² or more and 300 g/m ² or less, more preferably 50 g/m ² or more and 250 g/m ² or less, and 60 g/m ² or more. It is more preferably 200 g/m ² or less, and particularly preferably 70 g/m ² or more and 150 g/m ² or less.
When glass fiber nonwoven fabric is used, the basis weight is preferably 15 g/m ² or more and 300 g/m ² or less, more preferably 20 g/m ² or more and 200 g/m ² or less, and 30 g/m ² or more and 150 g. /m ² or less is more preferable.
When the basis weight is at least the above lower limit, the foamable phenol resin composition is less likely to seep out onto the surface of the face material. If the basis weight is equal to or less than the above upper limit, the adhesiveness between the foam and the face material can be enhanced. As a result, the face material is less likely to peel off from the foam, and the surface can be made more beautiful. In addition, it becomes easy to follow the conveying equipment such as a conveyor, and it is easy to improve the productivity of the phenolic resin foam. Particularly when the blowing agent comprises a halogenated saturated hydrocarbon, a fluorinated unsaturated hydrocarbon (HFO), a chlorinated fluorinated unsaturated hydrocarbon and cyclopentane, the inclusion of the blowing agent results in a foamable phenolic resin composition. lower viscosity. When the viscosity of the composition is low, the composition tends to permeate into the face material, and the composition tends to ooze out onto the surface of the face material. can prevent the composition from exuding.

When the face material is a glass fiber mixed paper, the content of the glass fiber relative to the basis weight of the face material is preferably 10% by mass or more and 90% by mass or less, more preferably 30% by mass or more and 70% by mass or less. When the glass fiber content is at least the above lower limit, the flame retardancy of the phenol resin foam board can be further improved. When the glass fiber content is equal to or less than the above upper limit, the peel strength between the phenol resin foam board and the face material can be sufficiently increased.
The remaining main component of the glass fiber mixed paper is cellulose fiber, and may also contain binders, inorganic fillers, colorants, and the like.

When the face material is a synthetic fiber nonwoven fabric, it is preferable to form a so-called emboss (thermocompression-bonded portion) having an uneven shape. By using the embossed face material, the adhesiveness between the face material and the foamable resin composition is further enhanced.
The embossed pattern (pattern) is not particularly limited, but examples thereof include a minus pattern, a point pattern, a weave pattern, and the like. A textured pattern or a negative pattern is preferable from the viewpoint that the embossed uneven shape is large and the adhesiveness to the foam layer can be further enhanced.
In order to emboss the synthetic fiber nonwoven fabric, for example, by a known spunbond method, a crimped continuous fiber web developed under cooling conditions directly below the spinneret is partially thermocompressed with a heat embossing roll, or by latent winding. It is manufactured by crimping a crimped long fiber web by heat treatment and partially heat-pressing it with a hot embossing roll.

In the thermocompression bonding portion formed during embossing, the area per thermocompression bonding portion is preferably 0.05 mm ² or more and 5.0 mm ² or less, more preferably 0.07 mm ² or more and 3.0 mm ² or less. . By using the face material within this range, it is possible to improve the adhesiveness between the expandable resin composition and the face material while suppressing the exudation of the expandable resin composition by the portion fixed by thermocompression. If the area is less ^than 0.05 mm ² , there is little bonding between fibers, physical strength such as friction strength is low, and the foamable resin composition tends to ooze out. The area of the fixed part is large, the texture is hard, and the adhesion between the foamed resin layer and the fibers of the face material is poor. Furthermore, the Frazier air permeability, which will be described later, may decrease, the curing time may become longer, and the closed cell ratio may decrease.
Incidentally, the thermocompression-fixed portion can generally be easily found visually or with an optical microscope or the like. The area of each thermocompression fixed portion can be measured by the following method.

<Percentage of the total area of the fiber fixing portion>
A 10-fold image of the surface of the nonwoven fabric was obtained with an optical microscope. Using image processing software (trade name “Photoshop (registered trademark)”, manufactured by Adobe Systems Incorporated), the total area of the thermocompression fixed part included in a square (unit area) of 100 mm long and 100 mm wide on the surface of the nonwoven fabric. was measured.

The minimum distance between the thermocompression bonding portions is preferably 0.05 mm or more and 5 mm or less, more preferably 0.08 mm or more and 2 mm or less. By using the face material within this range, it is possible to improve the adhesiveness between the foamed resin layer and the face material while suppressing the bleeding of the phenolic resin. If the minimum distance is less than 0.05 mm, there will be many portions fixed by thermocompression, the texture will be hard, and the adhesiveness between the foam layer and the fibers of the face material will tend to be poor. If it exceeds 5 mm, there is little bonding between fibers, physical strength such as frictional strength is low, and the foamable resin composition tends to exude. Moreover, it is preferable that the thermocompression-bonded portions are evenly distributed over the entire surface of the nonwoven fabric.

The density of the portions fixed by thermocompression is 5 pieces/cm ² or more and 150 pieces/cm ² or less, more preferably 5 pieces/cm ² or more and 50 pieces/cm ² or less, and 5 pieces/cm ² or more and 30 pieces/cm ² or less. More preferred. The thermocompression bonding portion density means the number of thermocompression bonding portions per unit area, and is expressed by the following equation (s).
Density of thermocompression-bonded portions (pieces/cm ² ) = [number of thermocompression-bonded portions (pieces)]/” [face material surface area (cm ² )] (s)
When the density of the portion to be fixed by thermocompression bonding is at least the above lower limit, the seepage of the expandable resin composition can be suppressed satisfactorily. If the density of the portion fixed by thermocompression bonding is equal to or less than the above upper limit, the adhesiveness between the foamed resin layer and the face material can be further improved, and the water absorption can be reduced. Further, if the density of the portion fixed by thermocompression bonding is equal to or less than the above upper limit value, the Frazier air permeability described later can be increased, and the curing time can be shortened. Also, low thermal conductivity can be maintained over a longer period of time.

The Frazier air permeability of the face material is preferably 60 cm ³ /cm ² ·sec or more and 900 cm ³ /cm ² ·sec or less, and is preferably 100 cm ³ /cm ² ·sec or more and 700 cm ³ /cm ² ·sec or less. More preferably, it is particularly preferably 200 cm ³ /cm ² ·sec or more and 500 cm ³ /cm ² ·sec or less.
If the Frazier air permeability of the face material is less than 60 cm ³ /cm ² ·sec, the curing time in the curing process will be long, or the moisture generated in the curing process will remain in the foam layer, and the residual moisture will be lost in the curing process. When removed, they may become pores and reduce the closed cell ratio.
A face material having a Frazier air permeability of more than 900 cm ³ /cm ² ·sec has a remarkably small basis weight or a remarkably low heat-compression fixing portion density. For this reason, the phenolic resin composition discharged onto the face material oozes out from the face material during the process of foaming and curing, which contaminates the manufacturing equipment. In addition, moisture from the outside easily reaches the foam layer, increasing the amount of water absorption.
The Frazier air permeability is a value calculated by measuring the amount of air passing through the face material using a Frazier tester according to JIS L 1096, and is measured for the face material before being laminated on the foam layer. be.

<Physical properties>
[density]
The density of the phenolic resin foam of the present invention is 15-50 kg/m ³ , preferably 20-40 kg/m ^{3 , more preferably 25-35 kg/m 3 .} If it is at least the above lower limit value, the compressive strength of the phenolic resin foam is likely to be further improved, and if it is at most the above upper limit value, it is easy to further improve the heat insulating properties of the phenolic resin foam.
The density is adjusted by the type and composition of the foaming agent, the type of surfactant, foaming conditions (heating temperature, heating time, etc.), and the like.
A method for measuring the density will be described later.

[Average bubble diameter (cell diameter)]
The average cell diameter of the phenol resin foam of the present invention is 200 µm or less, preferably 50 µm or more and 200 µm or less, more preferably 50 µm or more and 150 µm or less, still more preferably 50 µm or more and 120 µm or less, and most preferably 50 µm or more and 100 µm or less. If the average cell diameter is within the above range, the heat insulating properties of the phenolic resin foam can be further enhanced.
The average cell diameter is adjusted by a combination of the type or composition of the foaming agent, the type of surfactant, foaming conditions (heating temperature, heating time, etc.) and the like.
A method for measuring the average bubble diameter will be described later.

[Closed cell ratio]
The closed cell ratio of the phenolic resin foam of the present invention is 80% or more, preferably 85% or more, more preferably 90% or more, and may be 100%. If the closed cell ratio is at least the above lower limit, the heat insulating properties of the phenolic resin foam can be further enhanced.
The closed cell ratio is adjusted by a combination of the type or composition of the foaming agent, the type of surfactant, foaming conditions (heating temperature, heating time, etc.), and the like.
A method for measuring the closed cell content will be described later.

[Surface resistivity]
The surface resistivity of the phenolic resin foam of the present invention is 1×10 ¹² Ω/□ or less, preferably 1×10 ¹¹ Ω/□ or less, more preferably 1×10 ¹⁰ Ω/□ or less. When the surface resistivity is equal to or lower than the upper limit of the above range, it is difficult for chips to adhere, and the lower the surface resistivity, the more the adhesion of chips is suppressed. The lower limit of the surface resistivity is not particularly limited, but is preferably 1×10 ⁴ Ω/□ or more, more preferably 1×10 ⁵ Ω/□ or more, in order to achieve a good balance with other physical properties.
The surface resistivity tends to decrease as the halogenated unsaturated hydrocarbon content in the blowing agent increases. It is considered that the polarity of the halogenated unsaturated hydrocarbon contributes to the decrease in surface resistivity.
A method for measuring the surface resistivity will be described later.

[Equilibrium moisture content]
The equilibrium water content of the phenolic resin foam of the present invention is preferably 3 to 10% by mass, more preferably 3 to 8% by mass, and even more preferably 4 to 7% by mass. When the equilibrium water content is at least the lower limit of the above range, a low surface resistivity is likely to be obtained, and when it is at most the upper limit, the heat insulating properties can be further enhanced. A method for measuring the equilibrium moisture content will be described later.

The equilibrium moisture content of the phenolic resin foam can be adjusted by the conditions of the post-curing/drying process.
The post-curing/drying process is performed by adjusting the temperature and time in the curing furnace. When the heating temperature is in the range of 80° C. or higher and 90° C. or lower, the heating is preferably performed for 4.5 hours or longer and 12 hours or shorter. Moreover, when the heating temperature is in the range of 91° C. or higher and 120° C. or lower, the heating is preferably performed for 1 hour or longer and less than 4.5 hours.
If it is less than the above lower limit, it will be in an undried state (drying is not sufficient), post-curing will not be completed, and not only will the cells become coarse and the closed cell rate will decrease, but also the equilibrium moisture content will increase, resulting in thermal conductivity. worsens. On the other hand, if the above upper limit is exceeded, drying by heating proceeds too much, and not only does the bubble burst and the closed cell ratio decreases, but the equilibrium moisture content becomes too low, so chips are generated when the phenolic resin foam is cut. Cheap.
At this time, the structure of the hot air curing furnace is not particularly limited, and may be a single structure or a composite structure. A hot air curing furnace may also be used as the curing furnace. In this case, the wind speed of the hot air is not particularly limited, but is usually 0.5 m/sec or more, preferably 1 m/sec or more. If the wind speed is less than 0.5 m/sec, the post-curing treatment takes too long time, the productivity is poor, and it is difficult to obtain a phenolic resin foam having the desired physical properties.

EXAMPLES The present invention will be described in more detail below using examples, but the present invention is not limited to these examples.
<Measurement method>
Methods for measuring the physical properties of the phenolic resin foam are as follows.
[density]
Density measures the density of a phenol resin foam according to JIS A 9511:2009.

[Average bubble diameter (cell diameter)]
A test piece is cut from approximately the center in the thickness direction of the phenolic resin foam. A cut surface of the test piece in the thickness direction is photographed at a magnification of 50 times. Four straight lines with a length of 9 cm are drawn on the photographed image. At this time, straight lines are drawn so as to avoid voids (spaces of 2 mm ² or more). The number of bubbles crossed by each straight line (the number of cells measured according to JIS K6400-1:2004) is counted for each straight line, and the average value per straight line is obtained. 1800 μm is divided by the average number of bubbles, and the obtained value is taken as the average bubble diameter.
[Closed cell ratio]
The closed cell ratio of the phenolic resin foam is measured according to JIS K7138-2006.
[Thermal conductivity]
Thermal conductivity is measured according to JIS A 1412-2.

[Surface resistivity]
Cut the phenolic resin foam parallel to the thickness direction. The cutting position shall be 5 cm or more inside from the end surface parallel to the thickness direction of the phenol resin foam. The surface resistivity of the cut surface immediately after cutting is measured at an applied voltage of 100 V using a surface resistivity meter (manufactured by Mitsubishi Chemical Corporation, product name: Hiresta UP MCP-HT450). However, when the surface resistivity is 1×10 ¹² Ω/□ or more, the applied voltage is measured at 1000V.

[Equilibrium moisture content]
The obtained phenolic resin foam with face material was cut to 200 mm in the width direction and 200 mm in the length direction, and then left for 14 days in an atmosphere at a temperature of 23 ° C. and a relative humidity of 50%. Let _m0 . The phenolic resin foam is placed in an oven at 104° C., the mass after 48 hours is m ₁ , and the equilibrium moisture content (unit: mass %) is calculated by the following formula (1).
Equilibrium water content = (m ₀ - m ₁ )/m ₀ × 100 (1)

<Examples 1 to 7, Comparative Examples 1 to 5>
Examples 4 and 5 are reference examples.
Using the foaming agents shown in Tables 1 and 2, phenolic resin foams were produced by the following method. Tables 1 and 2 show the addition amount of the foaming agent used in each example with respect to 100 parts by mass of the phenolic resin.
Liquid resol type phenolic resin (Asahi Organic Chemicals Industry Co., Ltd., trade name: PF-339) 100 parts by mass, castor oil EO adduct as a surfactant (addition mole number 30, HLB = 11) 4.5 parts by mass, 4 parts by mass of urea was added as a formaldehyde catcher, mixed, and allowed to stand at 20° C. for 8 hours.
To 108.5 parts by mass of the mixture thus obtained, a blowing agent shown in Tables 1 and 2 was added, and 16 parts by mass of a mixture of p-toluenesulfonic acid and xylenesulfonic acid was added as an acid catalyst, followed by stirring and mixing. Then, a foamable phenolic resin composition was prepared.
A first surface material (material: polyester non-woven fabric, weight per unit area: 30 g/m ² , density of thermocompression fixed portions: 8 pieces/cm ² , Frazier air permeability: 300 cm ³ / cm ² · sec), 18 pieces are arranged at equal intervals in the direction perpendicular to the running direction (hereinafter also referred to as the length direction) of the first face material (hereinafter also referred to as the width direction). It was ejected from the nozzle that is A second face material (material: polyester non-woven fabric) was layered thereon. An uncured product was formed in which the expandable phenolic resin composition layer was sandwiched between the upper surface of the first face material and the lower surface of the second face material.
The uncured material was heated at 70° C. for 300 seconds to be foam-molded (foaming/curing process), and post-cured/dried at the heating temperature and time shown in Tables 1 and 2 (post-curing/drying process). Then, it was cut into a width direction of 1820 mm and a length direction of 910 mm to produce a 45 mm thick phenolic resin foam with face material.
Density, average cell diameter, closed cell content, thermal conductivity, equilibrium moisture content and surface resistivity were measured by the above methods. The results are shown in Tables 1 and 2 (hereinafter the same).

<Examples 8 and 9>
A phenol with face material was prepared in the same manner as in Example 1 except that an alkyl ether surfactant (manufactured by Nikko Chemicals, product name "NIKKOL BB-20", HLB = 16.5) was used as a surfactant. A resin foam was produced.

As shown in the results of Tables 1 and 2, Examples 1 to 9 can reduce the surface resistivity compared to Comparative Examples 1 to 5, and the physical properties of the phenolic resin foam such as thermal conductivity It was good.

Claims (2)

A phenolic resin foam comprising a phenolic resin, a blowing agent comprising a saturated hydrocarbon and a halogenated unsaturated hydrocarbon, and a surfactant, wherein
The surface material is made of polyester nonwoven fabric and has 5 to 150 pieces/cm ² of thermocompression fixed portions on both sides, the proportion of the halogenated unsaturated hydrocarbon in the foaming agent is 30 to 70% by mass, and the surfactant The agent has an HLB of 8 to 18, a density of 15 to 50 kg/m ³ , an average cell diameter of 50 to 150 μm, a closed cell rate of 80% or more, and a thermal conductivity of 0.0186 or less, measured by the following method. A phenolic resin foam having a surface resistivity of 1×10 ¹² Ω/□ or less and an equilibrium moisture content of 3 to 10% by mass as measured by (I).
Measurement method (I): A phenolic resin foam is cut parallel to the thickness direction. The cutting position shall be 5 cm or more inside from the end surface parallel to the thickness direction of the phenol resin foam. The surface resistivity of the cut surface immediately after cutting is measured at an applied voltage of 100V. However, when the surface resistivity is 1×10 ¹² Ω/□ or more, the applied voltage is measured at 1000V. A method for producing a phenolic resin foam according to claim 1,
A foamable phenolic resin composition containing a phenolic resin, a blowing agent containing a saturated hydrocarbon and a halogenated unsaturated hydrocarbon, a surfactant having an HLB of 8 to 18, and an acid catalyst is used to form a thermocompression fixing part. After discharging onto a polyester nonwoven fabric having 5 to 150 particles/cm ² , a foaming and curing step of heating, foaming and curing, and after the foaming and curing step, the foamable phenolic resin composition is dried and further cured. It has a post-curing/drying process,
The ratio of the halogenated unsaturated hydrocarbon in the foaming agent is 30 to 70% by mass,
A method for producing a phenolic resin foam, wherein the post-curing/drying step is carried out at 91° C. or higher and 120° C. or lower for 1 hour or longer and 4.5 hours or shorter.