JP2020186148A - Coated inorganic fiber porous body - Google Patents

Abstract

To provide a coated inorganic fiber porous body which is suitable for use under a higher temperature because, even though inorganic fibers which constitute an inorganic porous body has good thermal resistance, thermal resistance of a binder such as a silane coupling agent and the like is limited.SOLUTION: The coated inorganic fiber porous body comprises: a porous body 1 containing inorganic fibers except asbestos; and a coating member 2 which coats at least a portion of a surface of the porous body. In the porous body, a content of the inorganic fibers relative to all inorganic components is 80 mass% or more, a content of the inorganic fiber and the coupling agent relative to the whole of the porous body is 95 mass% or more, a content of the organic binder is 0.5 mass% to 10 mass%, a bulk density of the porous body is 0.001 to 0.1 g/cm3, and an emissivity of the coating member is lower than an emissivity of the porous body. The coating member contains a metal and has an emissivity of 0.5 or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a coated inorganic fiber porous body including an inorganic fiber porous body and a coating member, and its use.

Inorganic fiber porous material (foam) has elasticity similar to polyurethane foam and polyethylene foam, is lightweight, has excellent heat insulation and sound absorption, and is nonflammable, so it can be used as heat insulation and sound absorption materials for various industries. Can be used.
Asbestos fiber is the most suitable as the inorganic fiber used for producing this kind of porous body, but in recent years, it has become difficult to use asbestos fiber for environmental hygiene reasons, so an inorganic fiber other than asbestos fiber was used. Porous bodies have been developed.
For example, Patent Document 1 discloses that an inorganic fiber whose surface is charged is foamed using a surfactant having a hydrophilic group having a reverse sign to obtain a foam.

International Publication No. 2016/121400

The inorganic fiber porous body maintains its integrity by binding the inorganic fibers to each other with a binder. Inorganic fibers The inorganic fibers constituting the porous body have good heat resistance, but the heat resistance of a binder such as a silane coupling agent is limited. Therefore, there is room for further improvement from the viewpoint of using the inorganic fiber porous body as a heat insulating material, a sound absorbing material, or the like at a high temperature.
An object of the present invention is to provide a coated inorganic fiber porous body suitable for use at a high temperature.

According to the present invention, the following coated inorganic fiber porous bodies and the like are provided.
1. 1. Porous bodies containing inorganic fibers excluding asbestos,
Includes a coating member that covers at least a portion of the surface of the porous body.
The bulk density of the porous body is 0.001 to 0.1 g / cm ³ .
A coated inorganic fiber porous body in which the emissivity of the covering member is lower than the emissivity of the porous body.
2. 2. The coated inorganic fiber porous body according to 1 above, wherein the emissivity of the covering member is 0.5 or less.
3. 3. The coated inorganic fiber porous body according to 1 or 2, wherein the covering member contains a metal.
4. The coated inorganic fiber porous body according to any one of 1 to 3 above, wherein the covering member covers one side or both sides of the sheet-shaped porous body.
5. The porous body containing the inorganic fiber contains the inorganic fiber excluding asbestos and the coupling agent, and contains the coupling agent.
The content of the inorganic fiber in all the inorganic components is 80% by mass or more.
The inorganic fiber porous body according to any one of 1 to 4, wherein the content of the inorganic fiber and the coupling agent with respect to the entire porous body is 95% by mass or more.
6. The porous body containing the inorganic fiber contains the inorganic fiber excluding asbestos and the organic binder, and contains
The inorganic fiber porous body according to any one of 1 to 4, wherein the content of the inorganic fiber is 90% by mass or more.
7. The inorganic fiber porous body according to 6 above, wherein the content of the organic binder is 0.5% by mass or more and 10% by mass or less.
8. The inorganic fiber porous body according to any one of 1 to 7, wherein the inorganic fiber is glass fiber.

According to the present invention, it is possible to provide a coated inorganic fiber porous body suitable for use at a high temperature.

It is sectional drawing which conceptually explains the coated inorganic fiber porous body which concerns on one Embodiment of this invention. It is the schematic of the high temperature reflectance / transmittance measuring apparatus used for measuring the emissivity. It is sectional drawing of the heating part of the high temperature reflectance / transmittance measuring apparatus used for measuring the emissivity.

The coated inorganic fiber porous body according to one embodiment of the present invention includes a porous body containing inorganic fibers other than asbestos and a coating member that covers at least a part of the surface of the porous body, and is bulky of the porous body. The density is 0.001 to 0.1 g / cm ³ , and the radiation rate of the covering member is lower than the radiation rate of the porous body.

Such a coated inorganic fiber porous body is suitable for use at a high temperature, and for example, even when the inorganic fibers constituting the porous body are bonded to each other by a binder (reinforcing material), the heat resistant temperature of the reinforcing material is exceeded. Can be used at high temperatures. It is presumed that the reason why such an effect is exhibited is that the temperature rise of the porous body is suitably suppressed by the covering member.

Conventionally, the silane coupling agent used as a reinforcing material is inherently excellent in water repellency, but cannot sufficiently exhibit water repellency at high temperatures, and is improved from the viewpoint of preventing deterioration of inorganic fibers due to moisture in the air. There was room. According to the coated inorganic fiber porous body of the present embodiment, deterioration of the inorganic fiber is prevented by easily maintaining the original water repellency of the silane coupling agent even at a high temperature. Not only when an inorganic binder such as a silane coupling agent is used, but also when another reinforcing material such as an organic binder is used, the inherent characteristics of the reinforcing material (water repellency, flexibility) at high temperatures. (Sex, etc.) can be suitably retained.

FIG. 1 is a cross-sectional view conceptually explaining a coated inorganic fiber porous body according to an embodiment of the present invention. In FIG. 1, 1 is a porous body and 2 is a covering member.

The coated inorganic fiber porous body according to the present embodiment is composed of the porous body 1 and the two covering members 2 and 2, and has a plate shape (corrugated plate shape) as a whole.

The porous body 1 will be described in detail later, but the emissivity (also referred to as emissivity) of the porous body 1 is, for example, 0.6 or more, 0.65 or more, 0.7 or more, 0.75 or more, or 0.8. It can be 0.99 or less, 0.98 or less, 0.95 or less, or 0.9 or less.
The emissivity of the porous body 1 and the emissivity of the covering member 2 described later mean values calculated by the following formula.
Radiance (-) = 1-Reflectance (-)-Transmittance (-)
Here, "(-)" means that the unit is dimensionless, and the reflectance (-) and the transmittance (-) are under the temperature condition of 25 ° C. using a high-temperature reflectance / transmittance measuring device. It means a value calculated by the following formula from the incident light intensity, the reflected light intensity and the transmitted light intensity measured when the measurement sample is irradiated with an electromagnetic wave having a wavelength of 2 to 15 μm.
Reflectance (-) = (Reflected light intensity / Incident light intensity)
Transmittance (-) = (transmitted light intensity / incident light intensity)

Examples of the high-temperature reflectance / transmittance measuring device include those shown in a schematic diagram in FIG.
In the high-temperature reflectance / transmittance measuring device X shown in FIG. 2, the incident light 71 having a wavelength of 2 to 15 μm emitted from the Fourier transform infrared spectrophotometer (FT-IR6100 type manufactured by JASCO Corporation) 6 is reflected. It is reflected by the mirror 8 and guided into the sample chamber, and irradiates the sample 10 attached to the center of the turntable 9. The sample 10 has a structure in which the sample 10 is heated by a halogen heater (UL-SH-V500 manufactured by Ushio, Inc.) 11 in a state of being attached to a holder h provided in the center of the turntable 9. The intensity of the reflected light or the transmitted light 72 from the sample 10 is detected by the detector 12 separately provided on the arm portion of the turntable 9 having the mounting portion of the sample 10 as the rotation axis and orbiting around the sample 10.

A structural example of the heating portion of the high-temperature reflectance / transmittance measuring device X is shown in FIG. 3 in a cross-sectional view.
As shown in FIG. 3, halogen heaters 11 are installed on the front surface and the back surface of the sample 10, and when the detector 12 captures the reflected light or the transmitted light from the sample 10, the halogen heater 11 blocks the optical path. It is installed at an angle on the top of the sample 10 so that it does not exist. When measuring the reflected light or the transmitted light, the halogen heater 11 is also rotated together with the sample 10 so that the surface temperature of the sample 10 can always be kept constant. Cooling water 13 is introduced from the outside into the bottom of the turntable 9 on which the sample 10 is installed and the halogen heater 11, and is circulated and cooled.

In this embodiment, the sheet-shaped porous body 1 is used. The thickness of the sheet-shaped porous body 1 is not particularly limited and can be appropriately set according to the purpose, application, etc., for example, it may be 0.2 mm or more, 0.5 mm or more, or 1 mm or more, and 50 mm or less. , 30 mm or less or 20 mm or less.

(Coating member)
The two covering members 2 and 2 cover both sides of the sheet-shaped porous body 1 and sandwich the porous body 1. The covering members 2 and 2 are each in the form of a sheet having a plurality of uneven structures. Since the covering member 2 has an uneven structure, the rigidity of the coated inorganic fiber porous body is improved, and the vibration damping property of suppressing the vibration of the coated inorganic fiber porous body itself is improved. The improvement of vibration damping property can also contribute to the improvement of sound absorption property and quietness.

The emissivity of the covering member 2 is lower than the emissivity of the porous body 1, and is preferably 0.5 or less, 0.4 or less, and more preferably 0.3 or less. The lower limit of the emissivity of the covering member 2 is not particularly limited and may be, for example, 0.001, 0.005 or 0.01.

The material of the covering member 2 is not particularly limited as long as it satisfies the above-mentioned emissivity condition, and preferably contains a metal. The metal is not particularly limited, and examples thereof include stainless steel, aluminum, magnesium, iron, alloys thereof, and those obtained by plating them.

The form of the sheet-shaped covering member is not particularly limited, and examples thereof include a metal plate and a metal foil.

The thickness of the covering member is not particularly limited and can be appropriately set according to the purpose, application and the like. For example, it may be 0.01 mm or more, 0.03 mm or more or 0.05 mm or more, and 3 mm or less and 3 mm. It can be less than or equal to or less than 1.50 mm.

The coated inorganic fiber porous body described above can be used as, for example, a heat insulating material or the like. When the coated inorganic fiber porous body is used as a heat insulating material, the surface of the coated inorganic fiber porous body provided with the covering member 2 can be installed so as to face the high temperature side (heat generating body side).

In the above description, the case where the covering member covers both sides of the sheet-shaped porous body has been mainly shown, but the present invention is not limited to this. The covering member may cover one side of the sheet-shaped porous body.

In the above description, the case where the porous body is in the form of a sheet is mainly shown, but the present invention is not limited to this. The porous body can have any shape, and the covering member may be provided so as to cover at least a part of the surface of the pore body.

In the above description, the case where the covering member is in the form of a sheet having an uneven structure is mainly shown, but the present invention is not limited to this. The covering member may be in the form of a flat sheet. Further, the covering member is not limited to the case of a sheet shape, and may have an arbitrary shape.

(Perforated body)
Next, the porous body will be described in detail.
The porous body used in each of the above-described embodiments has a bulk density (normal temperature (about 20 ° C.), compression rate 0%) of 0.001 to 0.1 g / cm ³ . When the bulk density is in the above range, the flexibility can be increased and the deformation characteristics can be improved. The lower limit of the bulk density is preferably smaller, but in consideration of strength and compressive stress, it is preferably 0.005 g / cm ³ or more, and more preferably 0.007 g / cm ³ or more. The upper limit is preferably not 0.050 g / cm ³ or less, more preferably 0.030 g / cm ³ or less.

The above-mentioned porous body is obtained, for example, by foaming a liquid in which inorganic fibers are dispersed and then removing the liquid. Upon foaming, a surfactant can be added to the liquid. In addition, the foam from which the liquid has been removed can be heat-treated, if necessary. Further, the porous body can include a reinforcing material for reinforcing the bond between the inorganic fibers. Such a reinforcing material is incorporated into the porous body by adding it to the liquid, applying it to the foam from which the liquid has been removed, or applying it to the foam that has been heat-treated.
The obtained porous body has a so-called sponge structure in which innumerable cell-shaped voids made of inorganic fibers are formed, and is extremely lightweight.
Hereinafter, the constituent members of the porous body and the manufacturing method will be described.

(Inorganic fiber)
The inorganic fiber contained in the porous body is not particularly limited, and for example, one or more selected from ceramic fiber, biosoluble fiber (alkaline earth silicate fiber, rock wool, etc.) and glass fiber can be used. The porous body does not contain asbestos fibers.

The biosoluble inorganic fiber is, for example, an inorganic fiber having a physiological saline solubility of 1% or more at 40 ° C.
The saline solubility is measured, for example, as follows. That is, first, 1 g of a sample prepared by crushing an inorganic fiber to 200 mesh or less and 150 mL of physiological saline are placed in an Erlenmeyer flask (volume 300 mL) and placed in an incubator at 40 ° C. Next, horizontal vibration of 120 rpm is continuously applied to the Erlenmeyer flask for 50 hours. Then, each element (main element may be) silicon (Si), magnesium (Mg), calcium (Ca), sodium (Na), potassium (K) and aluminum (Al) contained in the filtrate obtained by filtration. Concentration (mg / L) is measured with an ICP luminescence analyzer. Then, the physiological saline solubility rate (%) is calculated based on the measured concentration of each element and the content (mass%) of each element in the inorganic fiber before dissolution. That is, for example, when the measurement elements are silicon (Si), magnesium (Mg), calcium (Ca) and aluminum (Al), the physiological saline solubility C (%) is calculated by the following formula. C (%) = [amount of filtrate (L) x (a1 + a2 + a3 + a4) x 100] / [mass of inorganic fiber before dissolution (mg) x (b1 + b2 + b3 + b4) / 100]. In this formula, a1, a2, a3 and a4 are the measured concentrations of silicon, magnesium, calcium and aluminum (mg / L), respectively, and b1, b2, b3 and b4 are the inorganic fibers before dissolution, respectively. The content (% by mass) of silicon, magnesium, calcium and aluminum.

The biosoluble fiber has, for example, the following composition.
Total of SiO ₂ , ZrO ₂ , Al ₂ O ₃ and TiO ₂ 50% by mass to 82% by mass
Total of alkali metal oxide and alkaline earth metal oxide 18% by mass to 50% by mass

Further, the biosoluble fiber can be composed, for example, having the following composition.
SiO ₂ 50-82% by mass
Total of CaO and MgO 10-43% by mass

The average fiber diameter of the inorganic fiber is not particularly limited, but a finer one is preferable. In one embodiment, the average fiber diameter of the inorganic fibers can be, for example, 0.08 μm to 4.0 μm, 0.1 μm to 2.0 μm, or 0.2 μm to 1.0 μm. The average fiber diameter can be obtained from the fiber diameters measured for 100 randomly selected fibers.

(Reinforcing material)
The reinforcing material is not particularly limited, and a material capable of bonding inorganic fibers to each other can be used. In one embodiment, the porous body may contain, as a reinforcing material, one or more selected from the group consisting of a coupling agent, an inorganic binder and an organic binder.

The coupling agent is not particularly limited, and examples thereof include a silane coupling agent and a titanium coupling agent. The silane coupling agent is not particularly limited, and examples thereof include methyltrimethoxysilane. The method of applying the coupling agent to the porous body is not particularly limited, and for example, a method of heating the coupling agent to attach the generated steam to the porous body and reacting with the steam can be used. By treating with steam, the coupling agent is hydrolyzed, dehydrated and condensed, and adheres to the porous body. As another method, a method in which the porous body is directly impregnated with the coupling agent, heated, and then brought into contact with water vapor may be used.

The inorganic binder is not particularly limited, and is, for example, SiO ₂ system (SiO ₂ particles, water glass (sodium silicate), Al ₂ O ₃ system (Al ₂ O ₃ particles, basic aluminum acid such as polyaluminum chloride, etc.), etc.). Phosphates, clay minerals (synthetic, natural) and the like can be mentioned. The method of applying an inorganic binder to a porous body is not particularly limited. For example, in the process of producing a porous body, an inorganic binder is added to a liquid in which inorganic fibers are dispersed. As another method, an inorganic binder may be applied to the porous body after removing the liquid or the porous body after heat treatment by coating or the like.

Organic binders are not particularly limited, and for example, rubber (latex) materials such as silicone rubber, acrylic rubber, natural rubber, and styrene-butadiene rubber, water-soluble resins such as polyethylene oxide, thermoplastic resins such as polypropylene, and heat such as phenol resins. One or more selected from the group consisting of curable resin can be used.
The organic binder can include polymers, preferably crosslinked polymers such as the rubber (latex) materials described above. The method of applying the organic binder to the porous body is not particularly limited, and for example, a method of containing the organic binder in a liquid in which inorganic fibers are dispersed can be used in the process of producing the porous body. As another method, an organic binder may be applied to the porous body after removing the liquid or the porous body after the heat treatment by coating or the like.

(Surfactant)
In one embodiment, the porous body can include a surfactant. Such a surfactant may be added for the purpose of foaming the above-mentioned liquid in the process of producing the porous body. Therefore, in other embodiments, such a surfactant may be eliminated by a treatment for removing the liquid, a heat treatment, or the like, and may not be contained in the porous body. As the surfactant, for example, one or more selected from the group consisting of a cationic surfactant, an anionic surfactant, an amphoteric surfactant and a nonionic surfactant can be used.

(Other ingredients)
The porous body can contain components other than those described above as long as the effects of the present invention are not impaired. Other components include, for example, functional materials such as a radiation shielding material, a sealing property improving material, and a sound absorbing property adjusting material. One type of functional material may be added alone, or two or more types may be added in combination.

The radiation shielding material is a material that imparts a function of shielding radiation (radiation) to a porous body. Here, radiation shielding can be achieved, for example, by reflection, absorption or scattering. As the radiation shielding material, for example, one or more selected from the group consisting of fiber and powder can be used.

The sealing property improving material is a material having a function of improving the sealing property (sealing property) of the porous body. As the sealing property improving material, for example, scaly powder can be used. The scaly powder has a scaly or plate-like particle shape, for example, talc, chlorite, cericite, mica, glass flakes, kaolin, graphite (scaly graphite), aluminum flakes, aluminum diboronidated. , Nickel flakes, boron nitride and the like can be used.

The sound absorbing property adjusting material is a material having a function of adjusting the sound absorbing property of the porous body. As the sound absorbing property adjusting material, for example, fibers having a diameter larger than that of the inorganic fibers contained in the porous body, fibers having a diameter smaller than that of the inorganic fibers contained in the porous body, and powder can be used. As the powder, for example, a scaly powder can be used, and the same material as the sealability improving material described above can be used.

(composition)
In one embodiment, the porous body is
100 parts by mass of inorganic fiber; 0 to 30 parts by mass, 0.5 to 20 parts by mass, 1 to 10 parts by mass or 1 to 5 parts by mass of reinforcing material; 0 to 5 parts by mass of surfactant, 0.1 to 5 parts by mass It can contain 0.5 parts by mass or 0.01 to 1 parts by mass; and other components in a ratio of 0 to 30 parts by mass, 0.5 to 20 parts by mass or 1 to 10 parts by mass. In addition, 0 part by mass means that the said component is not contained.

In one embodiment, 70% by mass or more, 75% by mass or more, 80% by mass or more, 85% by mass or more, 90% by mass or more, 95% by mass or more, 96% by mass or more, 97% by mass or more, 98% by mass of the porous body. % Or more, 99% by mass or more, 99.5% by mass or more, 99.9% by mass or more are substantially inorganic fibers; inorganic fibers and reinforcing materials; inorganic fibers and surfactants; or inorganic fibers, reinforcing materials and Consists of a surfactant. Here, the remainder of% by mass can be one or more selected from the other components described above, and at least one of the unavoidable impurities.

[Manufacturing method of porous body]
Next, an example of the method for producing the porous body described above will be described. As described above, in one embodiment, the porous body is composed of a foam obtained by foaming a liquid in which inorganic fibers are dispersed and then removing the liquid. Upon foaming, a surfactant can be added to the liquid. In addition, the foam from which the liquid has been removed can be heat-treated, if necessary. Further, the porous body can include a reinforcing material for reinforcing the bond between the inorganic fibers. Such a reinforcing material is incorporated into the porous body by adding it to the liquid, applying it to the foam from which the liquid has been removed, or applying it to the foam that has been heat-treated.
An example of using a coupling agent as a reinforcing material and an example of using an organic binder as a reinforcing material will be described in detail below.

(When using a coupling agent)
An example of a manufacturing method when a coupling agent is used as a reinforcing material is a manufacturing process for producing an inorganic fiber dispersion, a foaming step for foaming the inorganic fiber dispersion, and a dehydration step for drying the foam (porous). It is composed of a step of removing the dispersion medium) and a step of applying the coupling agent to apply the coupling agent. In order to promote the adhesion of the coupling agent, a firing step of firing the foam at a predetermined temperature may be added before the coupling agent applying step.

One aspect of the manufacturing process is a charging step in which the surface of the inorganic fiber is brought into contact with an alkaline or acidic treatment liquid to charge the charged inorganic fiber negatively or positively, and a dispersion liquid is prepared by adding a surfactant to the charged inorganic fiber. Includes a surfactant addition step to make. It is preferable to add a cationic surfactant when the surface of the inorganic fiber is negatively charged, or an anionic surfactant when the surface of the inorganic fiber is positively charged.

In the charging step, the zeta potential on the surface of the inorganic fiber is controlled by adjusting the pH using an alkaline or acidic treatment liquid. Specifically, the zeta potential on the surface of the inorganic fiber is negative or positive.

In the surfactant addition step, preferably, a surfactant having a hydrophilic group having a reverse sign is added to the charged inorganic fiber, and the hydrophilic group side of the surfactant is adsorbed on the surface of the inorganic fiber to cause a hydrophobic group. The inorganic fiber (outermost surface) is made hydrophobic by arranging the side opposite to the surface of the inorganic fiber. In this state where the surfactant is adsorbed on the surface of the inorganic fiber to make the surface of the inorganic fiber hydrophobic, when air is introduced and foamed by the foaming step described later, bubbles are formed on the hydrophobic group side of the surface of the inorganic fiber. Can be promoted to obtain a well-foamed foam. In other words, by controlling the zeta potential on the surface of the inorganic fiber, a surfactant is allowed to interact with the inorganic fiber to make the fiber hydrophobic, and bubbles are easily locked (attached) around the inorganic fiber to foam. Form the foam (sponge structure).

As the treatment liquid, any acid or base of an inorganic compound and an acid or base of an organic compound may be used as long as they can be dissolved in water to change the pH. The zeta potential on the surface of the inorganic fiber shall show a non-zero value, for example, -5 mV to -70 mV, -7 mV to -60 mV, -10 mV to -45 mV, + 5 mV to + 65 mV, + 7 mV to + 60 mV, or + 10 mV to + 45 mV. Since the pH for achieving a predetermined zeta potential differs depending on the type of fiber, the pH cannot be uniquely specified, but the pH is, for example, negatively charged at pH 7.5 to 13 and positive at pH 2 to 6. Can be charged to. The zeta potential can be obtained by dispersing the fibers in an aqueous dispersion medium adjusted to a predetermined pH and measuring the fibers using a general-purpose zeta potential meter (for example, Model FPA, manufactured by AFG Analytic).

Further, the charging step and the surfactant addition step in the manufacturing step can be carried out over time or at the same time. When the charging step and the surfactant addition step are carried out at the same time, the treatment liquid, the inorganic fiber and the surfactant can be mixed together. On the other hand, when the charging step and the surfactant addition step are carried out over time, the inorganic fibers can be preliminarily opened with a treatment liquid, dispersed and charged, and then mixed with the surfactant. In addition, as another aspect of the production step, an amphipathic substance, a silane coupling agent having a hydrophobic functional group, a titanium coupling agent having a hydrophobic functional group, or the like is used without using a surfactant. It is also possible to prepare an inorganic fiber whose surface has been hydrophobized by surface treatment by putting it in a dispersion liquid (dispersion medium). The coupling agent in this step is for making a hydrophobic state in order to form a foam. The coupling agent used in the subsequent coupling agent application step is for preventing the form of the foam from collapsing when it gets wet with water.

The amount of the surfactant in the dispersion can be appropriately adjusted from that of the inorganic fiber, and for example, the amount of the surfactant may be 0.01 to 1.0 part by mass with respect to 100 parts by mass of the glass fiber. The surfactant can be preferably 0.1 to 0.8 parts by mass, more preferably 0.2 to 0.7 parts by mass. If the amount of the surfactant added is too small, the surface of the inorganic fiber may not be sufficiently hydrophobized and the foamability may decrease, while if the amount of the surfactant is too large, the surfactants adhere to each other. It can be adjusted in view of the fact that the surface of the inorganic fiber may not be sufficiently hydrophobized.

In the foaming step, air (bubbles) is supplied from the bubble supply device to the inorganic fiber dispersion liquid, which is a mixture of the treatment liquid, the inorganic fibers, and the surfactant, and foamed. Air (bubbles) may be supplied to the inorganic fiber dispersion liquid by stirring to foam the inorganic fiber dispersion liquid without using the bubble supply device. The bubble magnification, bubble amount, and bubble diameter can be adjusted by such a bubble supply device and stirring.

In the dehydration step, the foam is dehydrated by drying (including natural drying) the dispersion medium contained in the dispersion at room temperature or a predetermined temperature outside normal temperature for a predetermined time (for example, 4 hours).

In the firing step, the foam is fired at a high temperature (for example, 450 ° C.) to remove the surfactant. The firing step can be carried out at the same time as the dehydration step.

In the coupling agent application step, the foam is reacted with the coupling agent and water vapor to apply the foam. Specifically, the steam generated by heating the coupling agent is attached to the foam and reacted with the steam. By treating with steam, the coupling agent is hydrolyzed, dehydrated and condensed, and adheres to the foam. For example, the foam and the coupling agent vapor are brought into contact with each other in a closed container (a closed container in which gas does not enter the container from the outside but the pressure can be increased by heating inside). After contact, water is put into a closed container to generate water vapor and react with the coupling agent. When a large amount of the coupling agent is applied, the foam may be directly impregnated with the coupling agent and heated instead of or in addition to the above treatment. Then it is brought into contact with water vapor.

In the porous body using the coupling agent, the porous body contains inorganic fibers other than asbestos and the coupling agent, and the content of the inorganic fibers in all the inorganic components is 80% by mass or more, and the total of the porous body The content of the inorganic fiber and the coupling agent is preferably 95% by mass or more.
For a specific example of this aspect, reference is made to International Publication No. 2016/121400.

(When using an organic binder)
An example of a manufacturing method when an organic binder is used as a reinforcing material is a manufacturing process for producing an inorganic fiber dispersion liquid, a foaming step for foaming the inorganic fiber dispersion liquid, and a dehydration step (dispersion) for drying the foam (porous material). It is a manufacturing method including a step of removing a medium).

One aspect of the manufacturing process includes a charging step of negatively or positively charging the surface of the inorganic fiber in water, a surfactant addition step, and an organic binder addition step.

For the charging step and the surfactant addition step, the description of the production method when the above-mentioned coupling agent is used is incorporated.

In the organic binder addition step, the organic binder can be added to water containing inorganic fibers. The organic binder can be added in the form of, for example, a resin emulsion. Such resin emulsions can include a polymer and a cross-linking agent for cross-linking the polymer. In one embodiment, the cross-linking agent acts to cross-link the polymer, for example, with a subsequent dehydration step.

In the fabrication steps described above, the surfactant addition step can be carried out simultaneously with or after the charge step. When the charging step and the surfactant addition step are carried out at the same time, the treatment liquid, the inorganic fiber and the surfactant can be mixed together. When the surfactant addition step is carried out after the charging step, the inorganic fibers can be pre-opened with a treatment liquid, dispersed and charged, and then mixed with the surfactant.
Also, the organic binder addition step can be carried out at the same time as the charging step or after the charging step. Further, the organic binder addition step can be carried out before or after the surfactant addition step, or at the same time as the surfactant addition step.

In addition, as another aspect of the production step, an amphipathic substance, a silane coupling agent having a hydrophobic functional group, a titanium coupling agent having a hydrophobic functional group, or the like is used without using a surfactant. It is also possible to prepare an inorganic fiber whose surface has been hydrophobized by surface treatment by putting it in a dispersion liquid (dispersion medium). The coupling agent in this step is for making a hydrophobic state in order to form a porous body. The coupling agent used in the subsequent coupling agent application step is for preventing the morphology of the porous body from collapsing when it gets wet with water.

For the foaming step, the description of the manufacturing method when the above-mentioned coupling agent is used is incorporated.

In the dehydration step, the foam (porous material) is dehydrated by drying (including natural drying) the dispersion medium contained in the dispersion liquid at room temperature or a predetermined temperature outside normal temperature for a predetermined time. From the viewpoint of preferably holding the organic binder, the drying temperature can be, for example, 200 ° C. or lower, 150 ° C. or lower, 100 ° C. or lower, or 90 ° C. or lower.

In one embodiment, the method for producing a porous body can further include a coupling agent applying step of applying a coupling agent to the dried porous body described above. In the coupling agent application step, the description of the manufacturing method when the above-mentioned coupling agent is used is incorporated. From the viewpoint of significantly exerting the effect of the organic binder, it is also preferable to omit the coupling agent applying step.

In another example of the production method when an organic binder is used as the reinforcing material, the porous body is, for example, a production step for producing an inorganic fiber dispersion (excluding the step of adding an organic binder) and an inorganic fiber dispersion. A foaming step of foaming, a dehydration step of drying the foam (porous body) (a step of removing the dispersion medium), a step of firing the dried foam (porous body), and a step of adding an organic binder to the fired product. And, obtained by a manufacturing method including.
The step before the firing step of the second manufacturing method is the same as the dehydration step of the first manufacturing method except that the organic binder addition step is not carried out.
In the firing step, the dried foam is fired at a high temperature (for example, 450 ° C.) to remove the surfactant. The firing step can be carried out at the same time as the dehydration step.
In the organic binder addition step, the organic binder is added to the fired product obtained by firing by a method such as coating or spraying.
In the step of drying the organic binder, water or an organic solvent, which is a dispersion medium contained in the applied organic binder-containing material, is dried and removed by heating or the like as necessary. When a crosslinkable organic binder is used, the organic binder can be crosslinked by, for example, the above-mentioned drying step or a crosslinking step such as a heat treatment that can be separately provided.

When an organic binder is used for the porous body, it is preferable that the porous body containing the inorganic fiber contains the inorganic fiber excluding asbestos and the organic binder, and the content of the inorganic fiber is 90% by mass or more.
In one embodiment, the content of the organic binder in the porous body is 0.5% by mass or more and 10% by mass or less.
The content of the organic binder in the porous body is, for example, 1% by mass or more, 1.5% by mass or more, 2% by mass or more, 2.5% by mass or more, 3% by mass or more, 3.5% by mass or more, 4% by mass. % Or more, or 4.5% by mass or more. Further, in one embodiment, the content of the organic binder in the porous body is, for example, 9.5% by mass or less, 9% by mass or less, 8.5% by mass or less, 8% by mass or less, 7.5% by mass or less. It can be 7% by mass or less, 6.5% by mass or less, 6% by mass or less, 5.5% by mass or less, or 5.0% by mass or less.

(When using an inorganic binder)
As described above, the description of the manufacturing method when the organic binder is used as the reinforcing material is appropriately referred to the manufacturing method when the inorganic binder is used as the reinforcing material instead of the organic binder.

[Characteristics of porous body]
Next, the characteristics of the porous body will be described. Desirable properties (for example, physical properties, etc.) can be appropriately imparted to the porous body according to the purpose, application, and the like.

In one embodiment, the porous body can have at least one or more selected from the following properties (1)-(7). In the following description, the normal temperature is 20 ° C. In one embodiment, the properties described below can be retained over the entire range of 5 to 35 ° C. according to JIS Z 8703.

(1) The compressive stresses when compressed at each compression rate of 0 to 90% at room temperature are 2.5 MPa or less, 2.0 MPa or less, 1.5 MPa or less, 1.3 MPa or less, 1.0 MPa or less. It is 0.8 MPa or less, 0.6 MPa or less, 0.4 MPa or less, 0.2 MPa or less, 0.05 MPa or less, or 0.02 MPa or less. The lower limit is 0 MPa.
More preferably, the porous body has all the compressive stresses of 2.5 MPa or less, 2.0 MPa or less, 1.7 MPa or less when compressed at each compressibility of 0 to 90% at a high temperature (450 ° C.). It is 1.5 MPa or less, 1.3 MPa or less, 1.0 MPa or less, 0.8 MPa or less, 0.6 MPa or less, 0.4 MPa or less, 0.2 MPa or less, or 0.04 MPa or less. The lower limit is 0 MPa.
The compressive stress is calculated by dividing the load value during compression of the porous body during the test by the area of the pressed surface in the direction orthogonal to the compression direction (for example, the product of the vertical dimension and the horizontal dimension). For the load during compression, measure the dimensions of the porous body, set the compression rate (0 to 90%) with the thickness of the porous body as 100%, and use a material tester (Autograph, Shimadzu Corporation). It is the load value when compressed to a predetermined thickness (2 mm / min). Compressive stress N / m ² = measured load (N) ÷ sample area (m ² )

(2) The compressive stress when compressed at a compressibility of 80% at room temperature (or all the compressive stresses when compressed at each compressibility at a compressibility of 0 to 80%) is 0.1 MPa or less, 0.5 MPa or less, It is 0.3 MPa or less, 0.1 MPa or less, 0.08 MPa or less, 0.06 Pa or less, 0.04 Pa or less, 0.02 Pa or less, 0.01 MPa or less, 0.008 MPa or less, or 0.005 MPa or less. The lower limit is not limited, but is usually 0.0001 MPa or more or 0.00001 MPa or more.
The compressive stress is measured in the same manner as in the above characteristic (1).

(3) The restoration rate when compressed at a compression rate of 80% (preferably each compression rate from 0 to 90%) at room temperature is 50% or more, 60% or more, 70% or more, 80% or more, 85% or more. 90% or more, or 95% or more. The upper limit is not limited, but is usually 99% or less.
More preferably, the restoration rate when compressed at a compression rate of 80% at high temperature (450 ° C.) (preferably each compression rate from 0 to 90%) is 50% or more, 60% or more, 70% or more, 80%. Above, 85% or more, 90% or more, or 95% or more. The upper limit is not limited, but is usually 99% or less.
For the restoration rate, the compression rate is set (0 to 90%) with the thickness of the porous body as 100%, and compressed to a predetermined thickness (2 mm / min) using a material testing machine (Autograph, Shimadzu Corporation). The thickness of the sample after the test is measured and calculated from the following formula. Restoration rate (%) = (thickness after compression test ÷ thickness before test) x 100

(4) The apparent Young's modulus when compressed at a compression rate of 80% at room temperature is 1 MPa or less, 0.7 MPa or less, 0.6 MPa or less, 0.3 MPa or less, 0.1 MPa or less, 0.05 MPa or less, or 0.01 MPa. It is as follows. The lower limit is not limited, but is usually 0.0001 MPa or more.
The apparent Young's modulus is calculated based on the above-mentioned compressive stress and the amount of strain measured by measuring the dimensions of the sample.

(5) Bulk density at normal temperature (0% compression ratio), 0.13 g / cm ³ or less, 0.12 g / cm ³ or less, 0. 1 g / cm ³ or less, 0.09 g / cm ³ or less, 0.08 g / cm ³ or less, or 0.05 g / cm ³ or less, also, 0.001 g / cm ³ or more, 0.002 g / cm ³ or more , 0.003 g / cm ³ or more, 0.004 g / cm ³ or more, 0.005 g / cm ³ or more, or 0.006 g / cm ³ or more.
The bulk density is calculated by dividing the weight of the porous body by the apparent volume of the porous body (for example, the product of vertical, horizontal and height dimensions) measured using a dimensional measuring device (for example, a caliper).

(6) The integrated value [MPa · g / cm ³ ] of the bulk density and the compressive stress when compressed at a compression rate of 40 to 80% at room temperature is 0.30 or less, 0.28 or less, 0.1 or less. It is 0.05 or less, 0.01 or less, 0.001 or less, or 0.0005 or less.

(7) The average circle-equivalent diameter of the pore diameter in the porous body is 150 μm or more, 180 μm or more, 200 μm or more, or 250 μm or more, and 1000 μm or less, 800 μm or less, 700 μm or less, or 600 μm or less.
・ Average cell diameter (average circle equivalent diameter)
A sample was cut from the foam, and a line transmission image was taken at a resolution of 5 μm / pixel using an X-ray micro CT scanner (SkyScan1272 manufactured by BRUKER). From the obtained X-ray transmission image, a three-dimensional image was synthesized using the attached software (NRrecon and DATAVIEWER) to prepare a cross-sectional image inside the sample. All the pores of the obtained cross-sectional image were measured, and the average diameter equivalent to the circle was calculated. In the measurement, since the portion recognized as the pore has an elliptical shape, the major axis and the minor axis of the pore are measured, and the cross-sectional area is calculated by the following formula.
Pore cross-sectional area = major axis ÷ 2 × minor axis ÷ 2 × π
Further, the diameter corresponding to a perfect circle from the cross-sectional area is set as the diameter equivalent to a circle and calculated by the following formula. Then, the average of the equivalent circle diameters for all the pores in the image is calculated.
Circle equivalent pore diameter = 2 x √ (pore cross-sectional area ÷ π)
The average circle equivalent diameter is the arithmetic mean pore diameter calculated by the following formula.
(In the formula, d is the equivalent diameter of a circle and n is the number of pores.)

Each of the above-mentioned characteristics can be appropriately adjusted (controlled) in, for example, in the method for producing a porous body, depending on the surface active treatment method for the inorganic fiber, the concentration (content ratio) of the inorganic fiber, the expansion ratio, the amount of bubbles, the bubble diameter, and the like. ..

The use of the coated inorganic fiber porous body is not particularly limited, and it can be used even at high temperatures. The coated inorganic fiber porous body can be suitably used, for example, as a heat insulating material having excellent heat resistance. It can also be suitably used as a soundproofing material or a sealing material that can be used at high temperatures.
As heat insulating materials, for example, in the field of transportation equipment, heat insulating materials for railway vehicles, heat insulating materials for automobiles, heat insulating materials for aircraft, heat insulating materials for ships, and in the field of construction, heat insulating materials for walls and ceilings of houses and joint materials. Examples of general industrial fields include heat insulating materials for industrial furnaces, heat insulating materials for piping, and heat insulating materials for ducts.
As soundproofing materials, for example, in the field of transportation equipment, soundproofing materials for railway vehicles, soundproofing materials for automobiles, soundproofing materials for aircraft, soundproofing materials for ships, and in the field of construction, soundproofing materials for walls and ceilings of houses, etc., soundproofing materials for ducts. Examples include soundproofing materials for soundproof walls of highways and railway vehicles, soundproofing materials for gas water heaters, and the like.
Examples of the sealing material include a sealing material for a gas water heater, a sealing material for various industrial exhaust gases, a sealing material for fire prevention and smoke prevention of an elevator, and the like.

1: Porous body 2: Coating member

Claims (8)

Porous bodies containing inorganic fibers excluding asbestos,
Includes a coating member that covers at least a portion of the surface of the porous body.
The bulk density of the porous body is 0.001 to 0.1 g / cm ³ .
A coated inorganic fiber porous body in which the emissivity of the covering member is lower than the emissivity of the porous body. The coated inorganic fiber porous body according to claim 1, wherein the emissivity of the covering member is 0.5 or less. The coated inorganic fiber porous body according to claim 1 or 2, wherein the covering member contains a metal. The coated inorganic fiber porous body according to any one of claims 1 to 3, wherein the covering member covers one side or both sides of the sheet-shaped porous body. The porous body containing the inorganic fiber contains the inorganic fiber excluding asbestos and the coupling agent, and contains the coupling agent.
The content of the inorganic fiber in all the inorganic components is 80% by mass or more.
The inorganic fiber porous body according to any one of claims 1 to 4, wherein the content of the inorganic fiber and the coupling agent with respect to the entire porous body is 95% by mass or more. The porous body containing the inorganic fiber contains the inorganic fiber excluding asbestos and the organic binder, and contains
The inorganic fiber porous body according to any one of claims 1 to 4, wherein the content of the inorganic fiber is 90% by mass or more. The inorganic fiber porous body according to claim 6, wherein the content of the organic binder is 0.5% by mass or more and 10% by mass or less. The inorganic fiber porous body according to any one of claims 1 to 7, wherein the inorganic fiber is glass fiber.