JP2019148031A - Three-dimensional shape compact and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a three-dimensional shape molded body including a heat insulator that can give a three-dimensional shape in less than 5 minutes and can be applied to high-temperature heat insulation applications so as to satisfy productivity requirements, and A three-dimensional shaped article produced by the method is provided.
SOLUTION: A method for producing a three-dimensional shaped molded body from a plate-like body composed of inorganic fiber groups, the step of applying, coating, spraying or impregnating colloidal silica on one side of the plate-like body And a step of heating and pressurizing so that one surface of the plate-like body becomes a recess.
[Selection] Figure 2

Description

  The present invention relates to a manufacturing method of a three-dimensional shape molded body obtained by molding an inorganic fiber group into a three-dimensional shape, and a three-dimensional shape molded body manufactured by the method.

In a structure that becomes a catalytic reaction system at a high temperature, such as a manifold of a motorcycle or an automobile, the thermal insulation efficiency of the structure is important in order to maintain the reaction efficiency (at a high temperature). Further, in the vicinity of the muffler near the exhaust gas discharge port, a sound absorbing material for absorbing the engine sound and further its resonance sound is attached.
In general, heat insulation of such a structure is made by wrapping a heat insulating material made of a plate-like material such as a mat or felt mainly composed of glass fiber excellent in heat resistance or a flexible blanket around a structure requiring heat insulation. Is going on. As for sound absorption of automobile exhaust systems, since heat resistance is generally required, mats and felts mainly composed of inorganic fibers with excellent heat resistance, or flexible blankets and other plate-like bodies and sheets are subject to sound absorption. This can be done by wrapping around the structure.

  However, since these winding operations are time-consuming, in recent years, it seems to meet the outer shape of the structure to be mounted in order to improve the mounting workability of the heat insulator and the sound absorbing material and to improve the heat insulation efficiency and adhesion. It is desired at the production site to use a molded body molded in the above manner. In response to such demands, methods have been proposed for molding plate-like bodies such as mats and blankets or directly molding inorganic fiber groups.

Japanese Patent No. 4728506 (Patent Document 1) states that “the glass fiber is compressed into a desired compression shape and held at a temperature lower by 10 to 100 ° C. than the softening point, thereby fusing the contact points between the glass fibers. Thereafter, a method for forming a glass fiber molded article in which the glass fiber is cooled to solidify the fusion and maintain the compressed shape is proposed.
The above method is a method in which glass fiber aggregates (cotton-like or felt-like) are heated and pressurized so that the glass fibers are fused together and molded.
Such fusion molding depends on the type of glass fiber to be used and the temperature at the time of molding, but at least the surface of the glass fiber needs to be melted. For example, at 780 ° C. for 30 minutes (first embodiment), Like 780-810 degreeC for 15 minutes (2nd Embodiment), 10 minutes or more are required as high temperature which can fuse | melt glass, and as fusion time. Maintaining a high temperature of 700 ° C. or higher for 15 minutes or more is difficult to accept at the production site because of high costs and an obstacle to improving productivity.

In Japanese Patent No. 5715538 (Patent Document 2), as a method for producing a sound absorbing material, “a step of aggregating inorganic fibers and attaching a binder containing sugars and polyisocyanate between some of the inorganic fibers; Heating the inorganic fiber to which the binder is attached to a crosslinking temperature at which the saccharide is crosslinked with the polyisocyanate, and bonding the fibers partially with the crosslinked binder; and the inorganic fiber bonded with the binder Is heated to a temperature at which the binder is carbonized, and a method for producing an inorganic fiber aggregate including a step of carbonizing a part or all of the binder is proposed.

In the above method, a combination of saccharide and polyisocyanate is used as a binder, and fibers are bonded to each other by crosslinking of the binder to maintain the imparted shape.
In the examples, the molding by the sugar cross-linking reaction is performed at 230 ° C. for 1 minute. The short time of 1 minute can sufficiently meet the demands required at the production site, and there is an advantage that it is not necessary to increase the cost from the viewpoint of the heating temperature. However, since an organic substance is used as a binder, when used as a heat insulating material for a high-temperature reaction system at 250 ° C. or higher, the binder starts to gradually burn out, and at 600 ° C. or higher, the binder is burned out.

As a glass fiber thermoforming method that can be used as a high temperature reaction system heat insulating material of 250 ° C. or higher, US Pat. No. 7,889,943 (Patent Document 3) discloses an aggregate of silica glass fibers containing Al ₂ O ₃ ( Binderless) is set in a mold and molded at 400 degrees Fahrenheit (204.4 ° C.) to 1300 degrees Fahrenheit (704.4 ° C.) for 6 minutes to heat and harden the fibers to produce a conical shaped body. A method has been proposed. The silica-based glass fiber containing Al ₂ O ₃ used here has heat resistance up to 2000 degrees Fahrenheit (about 1000 ° C.) and is binderless, so it can be applied to high-temperature heat insulation applications. Can provide the body. On the other hand, regarding the heating time, although it depends on the heating temperature, it was disclosed that a molded body having a desired shape could not be obtained at 1112F (600 ° C) for 1 minute and at 700F (371 ° C) for 3 minutes. (Table 1).

Japanese Patent No. 4728506 Japanese Patent No. 5715538 US Pat. No. 7,889,943

As described above, according to the method of forming a glass fiber aggregate using an organic binder, molding in a short time of 1 minute is possible, but the heat resistance of the obtained molded body depends on the organic binder. Therefore, it cannot be applied to heat insulation applications at 600 ° C. or higher.
On the other hand, a binderless method, for example, a fusion molding method using fusion of glass fibers takes time for molding and is not satisfactory in terms of productivity.
According to the thermoforming method using a special glass fiber as proposed in Patent Document 3, it has become possible to shorten the molding time without impairing the original high-temperature heat resistance of the glass fiber. However, molding in 5 minutes or less has not been achieved.

However, at the production site, from the viewpoint of productivity, it is desired that the molding time be limited to less than 5 minutes.
The present invention has been made in view of the above circumstances, and the object of the present invention is to provide a three-dimensional shape in less than 5 minutes and be applicable to high-temperature heat insulation applications so as to satisfy productivity requirements. Another object of the present invention is to provide a method capable of producing a three-dimensional shape molded body including a proper heat insulator, and a three-dimensional shape molded body manufactured by the method.

  The method for producing a three-dimensional shape molded body of the inorganic fiber group of the present invention is a method for producing a three-dimensional shaped molded body from a plate-like body composed of the inorganic fiber group, on one side of the plate-like body, A step of coating, coating, spraying or impregnating colloidal silica; and a step of heating and pressurizing so that one side of the plate-like body becomes a concave portion.

  The colloidal silica is preferably a suspension dispersed in an aqueous dispersion medium as colloidal particles having an average particle diameter of 1 to 120 nm. In this case, a substantially spherical colloidal particle having an average particle diameter of 4 to 18 nm may be a suspension dispersed in an aqueous dispersion medium, or a substantially spherical colloidal particle having an average particle diameter of 4 to 18 nm is a chain. Or you may disperse | distribute in the water-system dispersion medium as the particle | grains aggregated in the branched form.

  The inorganic fiber is preferably a silica-based inorganic fiber having a hydroxyl group.

The pressurizing pressure is preferably performed by pressing the one surface at a pressure at which the thickness of the plate-like body is reduced by 5% or more and less than 50% before and after pressurization. It is preferable that temperature is 100-500 degreeC.
Under such conditions, the heating / pressurizing step can be performed with a heating / pressurizing time of less than 5 minutes.
As the plate-like body, a mat obtained by needle punching an inorganic fiber group is preferably used.

The present invention also includes a three-dimensional shape molded body produced by the above production method.
Therefore, the three-dimensional shape molded body of the present invention is a molded body in which inorganic fibers are intertwined and molded into a three-dimensional shape, and the cured silica material enters at least a part of the concave side surface of the three-dimensional shape. And a three-dimensionally shaped molded article having no silica cured product on the convex surface.
As said three-dimensional shape, the shape which has a recessed part suitable for the shape of an attachment location may be employ | adopted suitably.

  According to the production method of the present invention, it is possible to produce a three-dimensional shaped article suitable for an attachment site at a temperature lower than the glass softening point and the melting point and in a short time. And since the manufactured three-dimensional shaped molded body only needs to be attached at the work site, it is excellent in workability and helps to improve productivity. In addition, since the three-dimensional shape molded body of the present invention does not use an organic binder, it has excellent heat resistance based on the inherent heat resistance of the inorganic fiber that is a constituent material, and is a heat insulating material, a high-temperature sound absorbing material, and a buffer. It can also be suitably used as a material.

It is a schematic diagram which shows the structure of the plate-shaped object comprised by the inorganic fiber group used as a molding material. It is a structure schematic diagram for demonstrating the manufacturing method of one Embodiment of this invention. It is a cross-sectional schematic diagram which shows the structure of the three-dimensional shape molded object manufactured with the manufacturing method of one Embodiment of this invention. It is a structure schematic diagram for demonstrating the evaluation method employ | adopted in the Example. The tray type molded body No. 1 is a photomicrograph (magnification: 500 times) taken from the surface of the concave portion 1. 4 is a photomicrograph (magnification 500 times) taken from the concave surface of a tray-type molded body produced as Reference Example 2.

[Method for producing three-dimensional shape molded body]
A method for producing a three-dimensional shaped body from a plate-like body composed of inorganic fibers,
Applying, coating, spraying or impregnating colloidal silica on one side of the plate-like body; and heating and pressurizing so that one side of the plate-like body becomes a recess.

<Plate-like body composed of inorganic fibers>
First, a plate-like body used as a molding material will be described.
A plate-like body used as a molding material is a plate-like body of an inorganic fiber group. Specifically, a long fiber or short fiber aggregate is formed into a plate shape, and examples thereof include a nonwoven fabric, a mat, and a felt. Of these, a mat (needle mat) in which fibers are entangled by a needle punch and a plate-like body having a predetermined thickness is stabilized is preferably used.
The inorganic fibers constituting the plate-like body are not limited to one type, and may be a combination of two or more types of inorganic fibers.

Glass fibers, carbon fibers, metal fibers, ceramic fibers, and the like can be used as the inorganic fibers used for the constituent fibers of the plate-like body, and can be appropriately selected depending on the application.
Of these, glass fibers and ceramic fibers are preferably used in that they are excellent in heat resistance and have little spring back (elastic return) due to pressure molding.
In particular, silica fibers having hydroxyl groups, preferably silica fibers containing 0.1 to 20% Al ₂ O ₃ and 80 to 99.9% SiO ₂ are preferable. Such silica fibers are also excellent in terms of affinity with colloidal silica used as a binder.

The silica-based inorganic fiber having a hydroxyl group is a thermoformable glass fiber having 81% by weight or more of SiO ₂ and Si (OH) existing in a part of the SiO- network. . Such hydroxyl groups are used in the process of producing filaments or staple fibers from the starting glass material, such as metal or metal oxide ions (eg, Al ³⁺ , TiO ²⁺ or Ti ⁴⁺ , and ZrO ²⁺ or Zr) that were included in the starting glass material. ⁴⁺ ) proton substitution is thought to remain. Hydroxyl group contained in the silica fiber, at about 600 to 800 ° C., and the condensation reaction as follows (1), to form a new siloxane bond (Si-O-Si bonds), of _{H 2} O Can be released.

A specific example of the composition of such a silica-based inorganic fiber having a hydroxyl group is a composition represented by AlO _1.5 · 18 [(SiO ₂ ) _0.6 (SiO _1.5 OH) _0.4 ]. A commercially available product may be used, for example, belcottex (registered trademark) manufactured by belChem Fiber Materials GmbH.

  BELCOTEX® fibers are generally made from silicic acid modified with alumina and have a standard fineness of about 550 tex for standard type staple fiber play yarns. BELCOTEX® fibers are amorphous, typically about 94.5 weight percent silica, about 4.5 weight percent alumina, less than 0.5 weight percent oxide, and 0.5 weight percent. Contains less than percent other ingredients. The average diameter is about 9 μm, and there is little variation in diameter. The melting point is 1500 ° C. to 1550 ° C., and the heat resistance is up to 1100 ° C.

  A silica fiber having a hydroxyl group other than BELCOTEX, a silica fiber not having a hydroxyl group, other inorganic fibers, and the like can be appropriately selected and used depending on the purpose of use and use site.

  The fiber diameter of the inorganic fiber is about 6 to 13 μm, preferably about 7 to 10 μm. The length of the inorganic fiber depends on the type of plate-like body (felt, non-woven fabric, blanket, sheet, etc.), but in general, the length is 1 to 50 mm, preferably 3 to 30 mm, or about 30 to 200 mm. Preferably, a filament of about 50 to 150 mm is used. It is preferable that both filament and staple fiber do not substantially contain shots so that the safety standards of the Ordinance for Enforcement of the Industrial Safety and Health Law are cleared and the substances are not subject to regulation by the specific chemical substance prevention rules.

  In the case where the plate-like body is a needle mat, the fiber length is preferably 30 to 130 mm, more preferably 45 to 100 mm, from the viewpoint of mat formation by needle punching.

  The plate-like body to be used for molding has a thickness of about 3 to 25 mm, preferably 3 to 12 mm, and more preferably 4 to 10 mm. In the production method of the present invention, since pressure molding is performed, a plate-like body that is too thin may be too thin to obtain a desired heat insulating performance, and sufficient strength may be obtained. Is difficult to obtain. On the other hand, if the thickness is too large, the molding time becomes long, and the shape of the molded body tends to be difficult to maintain due to the relationship with the binder amount.

The density of the plate subjected to ^{moldings, 80kg / m 3 ~180kg / m} 3, more preferably ^{90kg / m 3 ~160kg / m 3} .
If the density becomes too high, pressure molding becomes difficult. On the other hand, when the density is too low, the shape retention after molding is lowered, and the strength as the final molded product becomes insufficient. In addition, the heat insulation tends to decrease.

<Colloidal silica>
The colloidal silica used in the production method of the present invention is a suspension in which agglomerates of silicon dioxide (SiO ₂ ) having OH groups on the surface by hydration become colloidal particles and are dispersed in a dispersion medium. Say.

  The dispersion medium is water, an organic solvent (for example, lower alcohols such as isopropanol, esters such as ethyl acetate; ethers such as ethylene glycol monoproether and propylene glycol monomethyl ether; ketones such as methyl ethyl ketone and methyl isobutyl ketone, cyclohexanone. It is possible to use a mixture of water and a lower alcohol (methanol, ethanol, propanol, isopropanol, etc.), but from the viewpoint of the working environment, water, water, etc. A water-based dispersion medium such as a mixed liquid of lower alcohol is preferably used.

The colloidal particles are formed by polymerizing silicon dioxide by forming siloxane bonds (Si—O—Si—), and the presence of SiOH groups and OH ⁻ ions on the surface of the particles makes it possible to electrically charge them with alkali ions. Multilayers are formed and stabilized by repulsion between particles.
In such colloidal particles as a dispersoid, the dispersion medium evaporates by heating, and the SiOH groups present on the particle surface form new siloxane bonds, so that the colloidal particles are integrated with each other (on the surface of the colloidal particles). Fusing) and can function as a binder.

The content of silicon dioxide in colloidal silica, that is, the solid content in the suspension is about 5 to 60% by mass, preferably 5 to 50% by mass, and more preferably about 10 to 40% by mass.
When the content rate of silicon dioxide, that is, the solid content rate becomes too low, the amount of coating for securing the amount of silicon dioxide necessary for maintaining the shape of the molded body increases. This is because it is disadvantageous in terms of productivity improvement because it is necessary to lengthen the amount of energy required for evaporation of water, which is a dispersion medium at the time of heat molding, and thus the heating time. Moreover, it is because the intensity | strength of the molded object finally obtained becomes inadequate when the coating amount to a plate-shaped object is inadequate.
On the other hand, when the content rate (solid content rate) of silicon dioxide becomes too high, the silicon dioxide powder remaining on the surface of the molded product after molding tends to increase. The silicon dioxide powder remaining on the surface of the molded body causes dust and causes deterioration in handling workability. Moreover, the stability of the colloidal particles which are dispersoids as a state of the suspension or dispersion before molding decreases, and gelation tends to occur. In addition, as the application method to the plate-like body, it is difficult to apply the spraying method, so the coating method and the coating method are applied. It becomes difficult to impregnate silicon dioxide into the inside of the body, and as a result, the binder function of maintaining the shape of the molded body may not be sufficiently exhibited.

  The size (average particle size) of the colloidal particles in the suspension is not particularly limited, but is 1 to 200 nm, preferably 2 to 100 nm, more preferably 3 to 50 nm, still more preferably 4 to 25 nm, particularly preferably. 4-18 nm. When the particle diameter is increased, the number of particles is relatively decreased when the content is the same, or the strength of the obtained molded product tends to decrease. Moreover, the shape retainability as a molded body also tends to be lowered.

  The average particle diameter here refers to the average primary particle diameter of the colloidal particles, and can be determined as a sphere equivalent diameter by a dynamic light scattering method, a Sears method, a BET method, a laser diffraction scattering method, or the like. What is necessary is just to select a measuring method suitably with the magnitude | size of colloidal silica. For example, it is preferable to use the BET method or the laser diffraction scattering method for fine particles of several tens of nm or less. The particle size can be measured by a dynamic light scattering method using a commercially available particle size distribution measuring apparatus. The Sears method is referred to Analytical Chemistry, vol. 28, p. 1981-1983, 1956, which is an analytical technique applied to the measurement of the average particle size of colloidal silica.

The colloidal particles in the suspension may be not only in the state where the spherical particles are dispersed individually, but also in the case where the fine particles are present as aggregates. As an aspect of aggregation, for example, the microparticles may be elongated to form a chain state or a beaded state.
Here, in the case of a chain-like or bead-like aggregate, it may be a case where fine silica particles are associated in the extending direction to form elongated chain-like secondary particles, or a part of the associated particles of silanol Secondary particles in which groups are condensed and bonded to each other may be used. In addition, the elongated shape is not limited to a straight line shape, and may be a branched shape or a partial mesh shape.
In the case of particles in a chain shape, a thread shape, or a bead shape, the average particle diameter includes a case where the particle diameter (secondary particle diameter) in the above range is assumed as a sphere. Such a secondary particle diameter can be measured by a dynamic light scattering method. In addition, it is preferable that the average particle diameter as a colloid primary particle (spherical particle) which comprises a secondary particle is 4-18 nm.

  When colloidal particles are aggregated or associated, a hard coating tends to be formed and tends to be excellent from the viewpoint of maintaining the applied three-dimensional shape. On the other hand, when the average particle diameter is increased, or when the chain is aggregated or aggregated in a chain or bead shape, a part of the chain or beaded aggregate particle remains on the surface layer without being impregnated into the plate-like body. This is because the ratio remaining on the surface of the molded body tends to be high, and the amount remaining after being powdered on the surface of the three-dimensional shape molded body tends to increase. Since the increase in the amount of residual powder on the surface of the molded product causes dust, from the viewpoint of handling and workability, a suspension (colloidal silica) in which the particle size is small and the spherical particles are dispersed individually. preferable.

  In addition, if the colloidal particles as the dispersoid become too large, it may be difficult to impregnate the inside of the plate-like body composed of inorganic fibers, or as a result, the function as a binder necessary for shape retention tends to be reduced. is there. From this viewpoint, the average particle size (primary particle size) of colloidal silica is preferably smaller.

The stability of colloidal particles is generally sensitive to pH. From the viewpoint of preventing gelation, it is preferably stabilized with alkalinity, specifically, Na ions.
The suspension usually contains metal ions that become cations for stabilizing the colloidal particles because the colloidal particles are usually charged with anions. The liquid property (pH) of the suspension is related to the stabilization of the colloidal particles, but is usually alkaline (pH 8 to 11) when stabilized with Na ions. However, the amount of strong alkali ions for stabilization may be reduced to about neutral to acidic (pH 4 to 7).

  The specific gravity at 20 ° C. of the suspension usually depends on the silica content. When the silica content is in the above range, it is about 1.10 to 1.40, preferably about 1.12 to 1.25. is there.

Furthermore, the viscosity at 25 ° C. is preferably 300 mPa · s or less, more preferably 100 mPa · s or less.
In general, when the viscosity becomes high, gelation tends to occur, and it becomes difficult to apply a spraying method as an application method to a plate-like body as described later. From the viewpoint of workability and productivity, it is preferably 80 mPa · s or less, more preferably 60 mPa · s or less.

  The colloidal silica used in the present invention, that is, the colloidal suspension of silicon dioxide, is derived from the method for producing colloidal silica, and a slight amount (about 500 to 300 ppm) of calcium, magnesium, Sr is contained in the silica sol. , Ba, Zn, Pb, Cu, Fe, Ni, Co, Mn and other divalent metals, Al, Fe. Trivalent metals such as Cr, Ti, and Y may be included.

<Molding method>
The method for producing a three-dimensional shape molded body of the inorganic fiber group of the present invention,
A method for producing a three-dimensional shaped body from a plate-like body composed of inorganic fibers,
Applying, coating, spraying or impregnating colloidal silica on one side of the plate-like body; and heating and pressurizing so that one side of the plate-like body becomes a recess.
Hereinafter, each step will be described.

  Examples of the shape of the molded body formed by molding include a tray shape, a hemispherical shape, a pipe shape, a semicircular cross-sectional shape, and a truncated cone shape, but other shapes may be used.

(1) Application process of colloidal silica In the application process described above, a suspension of silicon dioxide as colloidal silica is applied to one side of a plate-like body composed of an aggregate of fibers (fiber group), applied, sprayed, Or it is the process performed by making single-sided contact. Which of these is adopted can be appropriately selected according to the viscosity and solid content of the suspension of the colloidal silica to be used.

Coating, coating: brush coating, roll coating method such as doctor blade, gravure coater, etc .; screen printing using squeegee; spray coating using air spray gun, airless hand spray, pressure automatic air spray, etc .; colloidal silica only on one side It can be carried out by a contact method for contacting with a suspension.
Of these, the spray method is preferred from the viewpoint of workability and productivity. For example, as shown in FIG. 1, the method of spraying the colloidal silica (suspension) 3 from the single side | surface of the plate-shaped body 1 comprised with the aggregate | assembly (inorganic fiber group) of the inorganic fiber 2 is mentioned.

  When the silicon dioxide content (solid content) of the suspension is about 10 to 50% by mass, or when the viscosity is 300 mPa · s or less, the spray method is advantageous from the viewpoint of work efficiency.

The coating amount of colloidal silica is appropriately selected according to the solid content ratio of the suspension used. Therefore, the coating amount, as solid content per area of the plate is about 100 to 600 / ^{m 2,} preferably 100 to 400 g / ^{m 2,} more preferably 100 to 300 g / ^{m 2} approximately.
When the coating amount (solid content amount) is too large, colloidal silica is not easily impregnated inside the molded body, so that a silica film is easily formed on one surface (application surface) of the molded body. Since a hard silica film is inferior in flexibility and cushioning properties to an aggregate of inorganic fibers, it tends to be inferior in attachment workability. In addition, even when using a fine particle size colloidal silica that is easily impregnated inside the plate-like body, if the coating amount is too large, the amount of silica remaining on the plate-like body surface increases, as a result, Silica powder tends to remain on the surface of the molded body. Since such silica powder causes dust, it causes a decrease in handleability and workability.

  On the other hand, if the concentration (solid content) is too low, the amount of suspension for achieving a predetermined coating amount increases, so that it takes time to dry and the heat-curing time becomes longer, resulting in productivity. Cause a drop in If the coating amount is reduced from the viewpoint of productivity, the amount of silica that should function as a binder is reduced, so that it is difficult to maintain the three-dimensional shape.

(2) Heating / pressurizing process The heating / pressurizing of the plate-like body to which the colloidal silica is applied is usually performed by setting it in a mold heated to a predetermined temperature. At this time, the surface 1a to which the colloidal silica is applied is set so as to be a concave side surface in the target three-dimensional shape.
For example, as shown in FIG. 2, when using a pair of dies of a female mold 11 and a male mold 12, the convex surface of the male mold 12 and the colloidal silica application surface 1 a are set to face each other.

  The cured silica formed by heat solidification is poor in stretchability and flexibility as compared with the inorganic fiber group. Each of the three-dimensionally shaped molded bodies such as trays, hemispheres, and pipes has a surface on the outer peripheral side that has an increased elongation rate due to molding, so depending on the shape, it could not follow the elongation rate and was formed on the surface layer. Cracks may occur in the cured silica layer.

  In the case where the plate-like body is a predetermined cut from the raw fabric roll, the direction corresponding to the longitudinal direction of the strip-like body (for example, the longitudinal direction of the plate-like body) and the width direction of the strip-like body (for example, the lateral direction of the plate-like body) In some cases, the growth rate may be different. In such a case, it is preferable that the mold is set on the side corresponding to the longitudinal direction of the belt-like body on the side having a large elongation rate in relation to the shape of the molded body.

As shown in FIG. 2, the three-dimensional shape imparting to the plate-like body is generally performed by a press molding method using a press corresponding to a male mold. However, the plate-shaped body is clamped between the female mold and the hot platen, and air is blown from the mold side so that the sheet is brought into contact with the hot plate and softened, and then the blowing of air is stopped. A thermoforming method (pressure forming) that blows compressed air and presses against the molding surface of the female mold, clamps the sheet to a frame suspended above the mold, heats and softens, and then evacuates the sheet and molds the sheet It is also possible to use a vacuum forming method in which it is brought into close contact with the mold, cooled as it is, and formed into a three-dimensional shape.
In any method, pressurization is performed so that the concave portion (the convex surface of the mold) of the molded body, which has a small degree of expansion and contraction in the three-dimensional shape having irregularities, becomes the colloidal silica coated surface.

The applied pressure is the thickness reduction rate (T ₁ −T) when the thickness reduction rate of the plate-like body, that is, the thickness T2 (see FIG. 3) of the final molded body with respect to the initial thickness T1 (see FIG. 1) of the plate-like body. ₂ ) is a pressure that is less than 50%, preferably about 5 to 45%, more preferably about 10 to 40%.
A large thickness reduction rate means that the compression rate of the plate-like body is large. When the compression rate becomes too large, the elastic recovery of the inorganic fibers constituting the plate-like body is likely to occur, and as a result, the shape retention of the molded body is lowered. Further, from the viewpoint of heat insulation, a thicker one tends to have better heat insulation.
On the other hand, if the thickness reduction rate is too low, that is, if the compression rate is too small, the ratio of the fibers immobilized becomes low due to the relationship with the impregnation depth of the colloidal silica into the plate-like body, resulting in shape retention. Tends to be insufficient.

The heating temperature is 100 to 500 ° C, preferably 150 to 500 ° C, more preferably 150 to 400 ° C.
The heating temperature is a temperature necessary and sufficient for evaporating the dispersion medium (usually water) contained in colloidal silica (a suspension of silicon dioxide) in a short time, and may be appropriately selected in relation to the heating time. . The heating time can be shortened by increasing the temperature. When a high temperature of 600 ° C. or higher is selected, a hydroxyl group of colloidal silica can react to form a siloxane bond. However, from the viewpoint of production cost at the molding site, it is preferable that the heating temperature is low as long as productivity is not lowered. On the other hand, when an organic binder is used for producing a plate-like body, such as a nonwoven fabric or a needle mat, it is preferable to heat to a temperature higher than the temperature at which the organic binder is burned out. When such an organic binder remains, for example, in a molded product used for high-temperature applications such as a heat insulating material, the molded product may be colored dark due to deterioration of the organic binder or the like. On the other hand, when the silica fiber having a hydroxyl group is used as the constituent fiber of the plate-like body, when heated to 500 ° C. or higher, the fiber becomes hard and gives physical irritation to the skin surface of the handling worker, causing itching and the like. This causes a decrease in workability and handling. From the above viewpoint, the heating temperature is preferably in the above range.

The pressurization / heating time depends on the type of colloidal silica to be used (average particle diameter and shape of colloidal particles), the silica content of the suspension, the coating amount, the viscosity of the suspension, and the like.
When the colloidal silica suspension used in the present invention is used under the above conditions, it can be cured by heating within 5 minutes, and further within 3 minutes and 1 minute. When the heat curing is insufficient, the pressure-molded shape cannot be retained due to the elastic restoring force of the fiber. On the other hand, heating and pressurization for 5 minutes or more are not preferable from the viewpoint of productivity.

<Three-dimensional shaped molded body of inorganic fibers>
The three-dimensional shape molded body of the present invention is manufactured by the manufacturing method of the present invention. Therefore, specifically, it has the following configuration.

  A molded body in which inorganic fibers constituting the plate-like body are intertwined and molded into a three-dimensional shape. Specific shapes include a tray shape, a hemispherical shape, a pipe shape, a semicircular cross section, and a truncated cone shape. Etc. In such a three-dimensional shape, at least a part of the concave side surface or the inner peripheral side surface is bonded to each other with a cured product of colloidal silica, that is, silicon dioxide fused with a siloxane bond.

  The silicon dioxides may form a bridge. Moreover, the hydroxyl groups in colloidal silica may crosslink and form a siloxane bond. Furthermore, some colloidal silica particles may form bonds with some silica-based inorganic fibers. In such a case, the silica particles are stably held in the molded body, which can contribute to the reduction of silica powder that causes a reduction in dust and workability.

  Although the thickness of the said molded object is based also on the initial thickness of the plate-shaped body of the fiber used as a molding material, it is preferable that it is 3-15 mm normally, More preferably, it is 4-8 mm. When the constituent fibers are long, the tendency of the applied shape to return to the original shape again increases due to the elastic recovery of the fibers. On the other hand, when the fiber length is short, the retention of the three-dimensional shape is excellent, but the sound absorbing property and the heat insulating property are insufficient as the sound absorbing material and the heat insulating material which are the intended use of the three-dimensional shaped molded body.

Moreover, it is preferable that the density of a molded object is 100-300 kg / m < ³ >, More preferably, it is 130-270 kg / m < ³ >. A low density means that the fiber density in the molded body is low, which tends to cause a decrease in heat insulation performance. On the other hand, increasing the density of the compact means that the fiber compressibility is excessive, and if it exceeds 300 kg / m ³ , the fiber is likely to be elastically restored, and thus the three-dimensional shape of the compact is maintained. Sex is reduced.

  The three-dimensional shape molded body having the above-mentioned configuration is dependent on the thickness and density of the molded body and the type of fiber as the constituent material, but the void formed by the entanglement of the fiber group exhibits vibration reduction and heat insulation effect. Therefore, it can be used as a sound absorbing material, a heat insulating material, and a buffer material.

  In particular, when a silica-based fiber having a hydroxyl group is used as a constituent fiber, water generated by a crosslinking reaction at a high temperature of 600 ° C. or higher consumes heat energy as heat of evaporation, thereby exhibiting an excellent heat insulating effect. Can do. Specifically, it has a heat insulating property of about 600 ° C. or more and about 1000 ° C. In the case of such a three-dimensional shaped article of silica-based fiber having a hydroxyl group as a constituent fiber of the molded body, based on the silica-based fiber and silica used as a binder, 600 ° C. or higher, and further about 800 ° C. to 1000 ° C. Therefore, it can also be used as a sound-absorbing / insulating material that is attached to the exhaust part of an automobile, particularly near the manifold. The use of such a heat insulating material can suppress the temperature drop when the engine is stopped, and can improve the reaction efficiency of the high-temperature catalytic reaction, and thus the engine efficiency. Conventionally, a heat insulating sheet is wound and attached. However, by forming the heat insulating sheet into a three-dimensional shape having a recess along the shape of the attachment portion, the attachment workability can be improved.

[Manufacture of three-dimensional shaped products]
(1) Used material (1-1) Needle mat
A Frenzelit technical needle mat (isoTHERM® BCT) was used.
This needle mat is made of belCotem (registered trademark) 110 (composition is AlO _1.5 · 18 [(SiO ₂ ) _0.6 (SiO _1.5 OH) _0.4 ]] and a fiber diameter of 9 μm is formed into a mat by a needle punch method. The mat thickness is nominally 6 mm.

(1-2) Colloidal silica Colloidal silica having an average particle size and shape as shown in Table 1 (both used Na-type Snowtex (registered trademark) of Nissan Chemical Industries, Ltd.). It is a suspension in which the liquid is stabilized.
The chain colloidal silica is obtained by agglomerating silica particles having a primary particle diameter of 9 to 15 nm in a thread form. The beaded colloidal silica is obtained by agglomerating silica particles having a primary particle diameter of 18 to 25 nm in a bead shape. These average particle diameters shown in the table are average particle diameters of secondary colloidal particles measured by a dynamic light scattering method.

(2) Three-dimensional shape molded body No. 1-7 Production Colloidal silica was sprayed on one side of a needle mat of length x width x thickness 300 mm x 300 mm x 6 mm. A spray amount is 666 g / m < ² > (133-320 g / m < ² > in solid content) as a suspension.
Next, as shown in FIG. 2, the colloidal silica adhering side is set on the concave mold set at 300 ° C. so as to be the upper surface side of the mold, and set at 300 ° C. attached to the upper surface side. a hot press 12 that, 300 ° C., (corresponding to after pressing the thickness (T ₂₎ is the compression ratio to be 65%) the original thickness (T ₁₎ until the 100% and a thickness reduction rate of 35% when press In this state, after holding for 1 minute, the convex mold (heat press) was released, and a tray as shown in FIG. 3 was created. The distance (d1) between the side walls of the three-dimensional shape molded body 4 immediately after molding was 150 mm, and the inclination angle α of the side wall with respect to the horizontal plane was 70 °.
About the created tray, the shape retainability and the handleability were evaluated by the method described later. The results are also shown in Table 1.

(3) Reference examples 1 and 2
Without using colloidal silica, the plate-like body alone was heated at 300 ° C. for 1 minute (Reference Example 1) or 5 minutes (Reference Example) at a pressure of 65% after pressurization (thickness reduction rate 35%). 2), a tray-type molded body shown in FIG. 3 was produced.
About the created tray, shape retainability and handleability were evaluated. The results are also shown in Table 1.

[Evaluation method and evaluation results]
<Shape retention>
As shown in FIG. 4, with the prepared tray-shaped molded body, the guide roller with a load (w) is applied to the side wall of the molded body 4 with the bottom surface fixed, and the size of the load (W) is set. Therefore, the side wall was inclined (in FIG. 4, it is shown by a molded body 4 ′ having an inclined side wall). The amount of movement (x) of the bearing roller (diameter 32 mm, height 34 mm from the bottom of the molded body) corresponding to the load is measured, and the amount x of movement is the displacement amount x (unit: mm) based on the load. It was evaluated with. In addition, the measurement was performed about three molded objects and evaluated based on the average value.
Displacement per 10 g is less than 1 mm: best (◎)
Displacement per 10 g is less than 1 mm to less than 2 mm: good (◯)
Variation amount per 10 g is 2 mm to 5 mm: no problem (Δ)
Mutation amount per 10 g exceeds 3 mm: Poor (x)

<Handability>
The surface of the molded body on the binder coating side was visually observed, and the generation of powder causing dust was visually observed. Further, the surface of the molded body on the binder coating side was touched by hand, and the degree of powder adhesion to the hand was observed.
“△” when powder is generated and the powder is noticeably attached when touched by hand, but the amount of powder attached to the hand when touched by hand is problematic. The case where the amount was not so large was “◯”, and the case where no powder was observed was given as “◎”.

No. As can be seen from the comparison of 1, 2, and 5, as the average particle size of the colloidal particles increased, the shape retention decreased.
In the case of colloidal particles aggregated in a chain shape, the shape retention tends to be higher than colloidal silica in which spherical particles are dispersed alone (No. 6). However, in the case of agglomeration type colloidal silica, the amount of powder remaining on the surface of the molded body increased, and even when touched by hand, the powder adhered to the hand and was inferior in handleability (No. 6, 7).

  When no binder was used, it was difficult to maintain the shape even if the tray was formed by heating and pressurizing for 1 minute. When the heating / pressurizing time was 5 minutes, the tray shape was maintained, but the holding power was inferior to that when colloidal silica was used.

  The obtained three-dimensional shape compact No. For 1 and Reference Example 2, the concave surface was observed with a microscope (magnification: 500 times) and imaged. The micrographs taken are shown in FIGS. 5 and 6, respectively. Compared to FIG. 6 (Reference Example 2), in FIG. 5 (No. 1), it was confirmed that the fibers were cross-linked in some places, and it was confirmed that the colloidal silica played a role of connecting the fibers together. . Further, in FIG. 5, the cross-linking of the colloidal silica was observed closely in the surface layer portion to which the colloidal silica was applied, but almost no cross-linking was observed inside.

(4) Reference example 3
In place of colloidal silica, an isocyanate (block polyisocyanate “Blonate” (registered trademark) from Taiho Sangyo) was used, and after spraying 30% of the needle mat weight as a solid content on one surface of the plate-like body, 1 under the same conditions as in No. 1. The surface of the molded body adhered to the surface of the convex portion of the male mold, and it was difficult to release the molded body from the male mold. When the molded body was peeled off from the male convex part, a part of the fiber was stuck to the convex part surface.

  The method for producing a three-dimensional shape molded body according to the present invention can produce a molded body having a three-dimensional shape suitable for an attachment location in a short time of less than 5 minutes. It helps to improve productivity for both users (installation site of the molded product). Moreover, since the heat resistance inherent to the inorganic fiber that is a component of the molded body is maintained, it is also useful as a heat insulating material, a sound absorbing material, a buffer material, and the like used for high temperature holding applications.

DESCRIPTION OF SYMBOLS 1 Plate-shaped body 1a Colloidal silica application surface 2 Inorganic fiber 3 Colloidal silica 4 Three-dimensional shape molded body 11 Female mold 12 Male mold

Claims (12)

A method for producing a three-dimensional shaped body from a plate-like body composed of inorganic fibers,
Three-dimensional shape of inorganic fiber group, comprising: coating, coating, spraying or impregnating colloidal silica on one side of the plate-like body; and heating and pressing so that one side of the plate-like body becomes a concave portion Manufacturing method of a molded object.   2. The production method according to claim 1, wherein the colloidal silica is a suspension dispersed in an aqueous dispersion medium as colloidal particles having an average particle diameter of 1 to 120 nm.   The production method according to claim 2, wherein the colloidal silica is a suspension in which substantially spherical colloidal particles having an average particle diameter of 4 to 18 nm are dispersed in an aqueous dispersion medium.   The production method according to claim 2, wherein the colloidal silica is obtained by dispersing substantially spherical colloidal particles having an average particle diameter of 4 to 18 nm in a water-based dispersion medium as particles aggregated in a chain shape or a branched shape.   The said inorganic fiber is a silica type inorganic fiber which has a hydroxyl group, The manufacturing method of any one of Claims 1-4.   The pressure of the pressurization is performed by pressing the one surface at a pressure at which the thickness of the plate-like body is reduced to less than 50% by 5% or more before and after pressurization. The manufacturing method as described in.   The temperature of the said heating is 100-500 degreeC, The manufacturing method of any one of Claims 1-6.   The manufacturing method according to claim 1, wherein the heating / pressurizing step has a heating / pressurizing time of less than 5 minutes.   The manufacturing method according to claim 1, wherein the plate-like body is a mat obtained by needle punching an inorganic fiber group. A molded body in which inorganic fibers are intertwined and molded into a three-dimensional shape,
A three-dimensional shape molded body in which a silica cured product has penetrated into at least part of the concave side surface of the three-dimensional shape, and no silica cured product exists on the convex surface.   The three-dimensional shape molded body according to claim 8, wherein the inorganic fibers are silica-based inorganic fibers having a fiber diameter of 6 to 13 µm. The three-dimensional shape molded body according to claim 8 or 9, wherein the three-dimensional shape molded body is a molded body having a concave portion adapted to a shape of an attachment portion.