JPS62113528A - Porous molded form and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a porous molded form having uniform holes, a high porosity and a high strength by a method wherein a multitude of linear extruded materials, consisting of an inorganic substance, is laminated so as to form wave forms or loops in a plane orthogonal to the thickness of the molded form substantially. CONSTITUTION:A viscous elastic material, consisting of an inorganic substance, is extruded from a multitude of nozzle holes provided in an extruding dice 2 to form an unit linear extruded material 8 while said extruded material 8 is descended vertically to receive it on a receiving surface 14 in a spiral configuration. In this case, the receiving surface 14 or the extruding dice 2 is moved laterally by half way or return ways whereby said spiral or wavy material is laminated into the direction of height (the direction shown by an arrow sign H) and a porous molded form consisting of a plurality of layers is made, however, said liner extruded material forms continuous waveforms or loops having substantially an equal pitch in a plane orthogonal substantially to the direction of the thickness of a plate-like porous molded form substantially and is arranged under a condition that the unit linear extruded material is connected or entangled with at least one piece of the neighboring other unit linear extruded material.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a porous molded body and a method for manufacturing the same.

[Conventional technology]

In recent years, porous molded bodies have been used for applications such as furnace materials, adsorbents, sound absorbing materials, heat insulating materials, and tent carrier hats. As porous molded bodies, the following are conventionally known.

■As shown in Fig. 14, a viscoelastic material A made of an inorganic substance or a synthetic resin is linearly extruded through a number of nozzle holes 5 provided in an extrusion die 2, and is allowed to fall vertically.
Porous pores obtained by stacking the extruded linear extrudates 8 while keeping the distance between the top surface of the stack and the exit end of the extrusion die 2 approximately constant while winding the linear extrudates 8 spirally around the top surface of the stack. A body molded body in which a large number of linear extrudates 8 made of inorganic substances or synthetic resins are each spirally wound and laminated, and the spirally wound laminates 7 are joined to each other on adjacent surfaces. It is a porous molded body formed by intertwining or intertwining (JP-A-58-116134).

A typical example of the molded body is shown in FIG. 15.

Linear extrudate cross-sectional diameter: 1.5mmφ Turning outer circumference diameter Near, Ommφ Turning inner circumference diameter: 4. Ommφ Opening of surface layer*: Approximately 25% Due to its manufacturing method, such a molded body is produced under the condition that the linear extrudates 8 are subjected to mutual force, that is, in a situation where the linear extrudates 8 are forcibly restrained. By laminating and molding, a molded product can be obtained, and regularity can be obtained.

■By attaching a slurry-like inorganic substance to the surface of polyurethane foam, then drying and firing, a porous ceramic material (ceramic foam) with a shape and structure similar to that of polyurethane foam is created.

■A honeycomb molded body that is extruded through a honeycomb die.

■Porous material that utilizes the pores between particles obtained by consolidating inorganic materials with a fixed particle size with a binder and then sintering them.

[Problems with Prior Art] These conventional technologies are utilized in fields that take advantage of their respective characteristics, but when viewed from another perspective, they have the following drawbacks.

First, the porous molded body (2) is a porous molded body composed of a linear extrudate having a uniform cross section, and is a porous body with excellent performance in terms of strength. However, due to the manufacturing method, the resulting porous body has the following problems. That is, the viscoelastic material A is linearly extruded from a large number of nozzle holes 5 provided in the extrusion die 2 and is allowed to fall in the vertical direction, and the extruded linear extrudates are stacked spirally on the top surface of the stack in the vertical direction. Since it is a porous body obtained by
The size of the pores is non-uniform in the (starting part of rolling) and the end surface 9b of lamination (where the viscoelastic material is separated from the die surface and lowered to the final upper surface of lamination to complete the lamination) compared to the central part. . Moreover, this porous body is normally used as a furnace material, heat insulating material, or catalyst carrier by passing gas and liquid in the same direction as the stacking direction (the direction of the arrow in Fig. 14). The non-uniformity of the pore size between the lamination start surface or the lamination end surface and the exit surface is a serious defect as it allows for variations in usage conditions. On the other hand, in order to prevent this defect, it is possible to remove the uneven portions on both end faces by cutting and removing it, but when cutting, the linear extrudate is cut in a direction that reduces the wire diameter. Alternatively, since the cross section of the linear extrudate is exposed on the surface, the result is a porous body whose strength and width are inferior to the center at both ends, or a porous body which has the disadvantage that both ends are easily chipped. It is the body.

Further, although the void* (simplified void ratio per volume) can be made large, the aperture ratio is relatively small, as shown in the example shown in FIG. 15.

Additionally, the following two points may become problematic depending on the application. One point is that single-porous molded bodies are made by laminating linear extrudates in the direction of gravity, so although the pores may vary in size,
Straight through holes are likely to occur, and for example, when used as a filter material, these straight through holes will impede the filter effect. As a filter material, it is generally preferable to have three-dimensional, intricate pores. The second point is that the surface layer of the 6-pore porous body, which has a relatively small porosity, that is, the open area ratio, is composed of a linear extrudate that is rotated and laid down due to its manufacturing method. ing. As mentioned above, when considering filter materials, what is necessary for the filter function is uniform and intricate pores, and the proportion of linear extrudates that can be called aggregate that make up the pores is small. In other words, the one with a larger aperture ratio.

Although desirable in terms of filter efficiency, the present porous material is fundamentally inferior in that respect.

Next, the ceramic foam (3) has a regular dodecahedral skeleton structure and is a porous body with a large porosity of 80%.

Due to its manufacturing method, this porous body is made by attaching a slurry-like inorganic substance with an adjusted viscosity to the surface of polyurethane foam and firing it, and since no external pressure is applied to this inorganic substance, the constituent aggregate itself is also porous. It is of good quality. Therefore, it is inferior in strength to porous bodies made of dense aggregates that are subjected to external pressure such as extrusion molding, and in extreme cases, the inorganic materials that make up the porous bodies are more likely to be absorbed than the surface of the porous bodies. May scatter in fine powder form. In addition, the ceramic foam has polyurethane foam punch marks (empty M) inside its aggregate, and the cross-sectional shape of the cavity is quite acute. When viewed in the longitudinal direction, the skeleton is extremely thin at the center compared to both ends, making it a structure that is easily defective with notches here and there.

Next, regarding the honeycomb structure (3), this structure has a low pressure loss and a large contact area, and when used as a catalyst carrier, for example, it becomes a catalyst with extremely high reaction efficiency. However, since it has two-dimensional pores, when used as a filter, only the pores on the entrance surface can be used, and the Rta as a filter is extremely short compared to a porous body having E-dimensional pores.

Although willow moldings have uses as precision materials, their porosity is the smallest among ① to ②, making them lacking in versatility.

Generally, the strength of a porous body decreases in inverse proportion to its porosity.Therefore, it is out of the question if the overall shape can compensate for the decrease in strength, but consider a flat plate as a general-purpose shape. In this case, the strength affects the thickness of the flat plate, and furthermore, the thicker the plate, the greater the ventilation resistance, which narrows the industrial range of application. In addition, the use of porous bodies will continue to expand in the future, and the materials used will be ceramics, such as oxides such as alumina, mullite, cordierite, and zirconia, or carbides and nitrides such as SiC and Si3N4. For applications such as filtration media, heat insulation materials, catalyst carriers, etc. that require heat resistance and IFt tactility,
By making the material a porous material such as activated carbon or silica gel, it can be used in a wide variety of adsorption fields. However, in order to promote industrial use, a porous molded body with uniform pores, high porosity, and high strength is essential.

The present invention provides a porous molded body having exactly such characteristics.
This was completed as a result of repeated studies to overcome the problems of the technology described in the above issue and the shortcomings of the conventional technology such as ceramic foam.

[Summary of the Invention] The first invention according to the present application is a molded article composed of a large number of linear extrudates made of an inorganic substance, the linear extrudates having a direction approximately parallel to the thickness direction of the molded article. It is a porous molded body characterized by forming a waveform or a loop in a plane in orthogonal directions.

A second invention according to the present application is to extrude a viscoelastic material made of an inorganic substance through a number of nozzle holes provided in an extrusion die to form a unit linear extrudate, and to extrude the unit linear extrudate in a longitudinal direction. This is a method for producing a porous molded product, which is characterized by lowering the porous molded product to a receiving surface and landing it in a spiral or wave shape.

The inorganic material may be a porous inorganic material, a non-porous material, or an organic material.

First, porous #A organic materials include, for example, zeolite (whether synthetic or natural), γ-alumina,
Examples include silica gel, silica/alumina, boehmite, activated titania, activated carbon, and molecular sieve carbon. Further, examples of the non-porous inorganic substance include metal-resistant minerals such as mullite, corundum, and cordierite. These inorganic substances are generally available in the form of powder or granules.

In order to make these inorganic substances into viscoelastic materials, for example, a binder is added to the inorganic substances and kneaded, and the viscosity is adjusted to form a slurry.

There are no particular restrictions on the binder, and any binder can be used as long as it exhibits a caking function for powder and granules. Typical binders include MC, CMC, starch, and CM3 (carboxymethyl starch), HEC (hydroxyethyl heptalulose), HPC (hydroxypropylcellulose), sodium ligninsulfonate, calcium ligninsulfonate, polyvinyl alcohol,
Examples include organic binders such as acrylic esters, methacrylic esters, phenolic resins, and melamine resins; inorganic binders such as water glass, colloidal silica, colloidal alumina, colloidal titanium, bentonite, and waste acid aluminum; In addition, it is preferable that the blending ratio of the binder is 35% or less (based on the total kneaded material) in terms of dry amount.If this value is exceeded, the strength of the final product will decrease, so it is recommended. Can not.

There are no restrictions on the mixing and kneading means, and any known device or machine may be used. However, if a screw extrusion molding machine is used to extrude the linear material, the screw of the molding machine may be used. You can also mix*.

The thus kneaded material is extruded into a linear product using the above-mentioned screw extruder or plunger extruder.

[Description of Embodiments] (Claim 2) This molded product can be applied to each purpose by gathering independent linear products and assembling them in a casing. By joining or intertwining with at least one of these casings, it is useful as a high-strength integrally molded product that does not require a casing.

(Claim 3) By making the molded body shape plate-like, it becomes a porous plate with a large plate and homogeneous pore surface, which could not be achieved with the conventional technology, and is suitable for various high-temperature filter plates, adsorption, and separation. It is useful as a board, etc.

The bonding or intertwining of adjacent medium linear extrudates is, for example, as shown in FIGS. 1 to 4. Figures 1 and 2
The figure shows the case of a single layer, in which adjacent unit linear extrudates are joined or intertwined in the same plane. 3 and 4 show the case of two layers; in FIG. 3, the upper layer and the lower layer are substantially orthogonal, and in FIG. 4, the upper layer and the lower layer are substantially parallel.

In this case, the unit linear objects of the lower layer (dotted line) and the upper layer (actual m) are joined or intertwined.

Note that linear extrudates that have been given adhesiveness with a binder are
It retains its properties even after extrusion, and can be easily joined by contacting it with a small amount of force.

(Claim 4) When the inorganic substance is a non-porous material, it can be used as a high-strength filter material, a heat insulating material, in fields where heat resistance or chemical resistance is important,
It is useful as a sound deadening member, etc.

(Claim 5) When made of a porous material, it is useful as an adsorption/separation material for various gases and liquids, or as a catalyst carrier, taking advantage of its porosity.

(Claim 6) In the case of a width layer in the thickness direction, for example, by using silica gel, activated carbon, etc. as the material, it can be used as a dehumidifying material with ultra-low pressure drop and an adsorbent for removing bad odors. This ultra-low pressure drop means that the target gas and liquid can easily pass through the filter, resulting in system downsizing and
It also produces economic effects such as reduced energy consumption.

When multiple layers are used, the applications are further expanded.For example, by using ceramic as the material, it can be used as a filter for removing impurities in molten metal, a filter for purifying high-temperature exhaust gas, heat insulation, and sound deadening materials. By using a porous material such as silica gel or activated carbon zeolite, a molded article with high adsorption and separation capacity and high strength can be obtained.

(Claim 7) A continuous corrugated or loop-shaped linear extrudate with a substantially equal pitch in a plane substantially perpendicular to the thickness direction is formed in a direction in which adjacent layers in the thickness direction are orthogonal to each other. The arrayed porous material has a characteristic of having little anisotropy in terms of strength (bending strength and tensile strength).

(Claims 8 and 9) In addition, this continuous waveform 9 or loop-shaped linear extrudate is generally a large plate-like porous material whose wire diameter or pitch may be changed in the thickness direction. When using the body as a filter, it is preferable not to install anything that reduces the effective surface area of the filter, such as a support material, on the filter side, or if the support material itself is used at high temperatures, the support material itself needs to be high-strength at high temperatures. Therefore, it is economically disadvantageous. but,
It is natural that the overall strength decreases as the size increases, and in order to compensate for this decrease in strength, the plate thickness is generally increased. Furthermore, the problem here is that
As the plate thickness increases, the ventilation resistance also increases, resulting in problems such as an increase in the size of various auxiliary equipment.

In other words, in large plate-like porous bodies, etc., there is low ventilation resistance.
In addition, high-strength products are required, and although Saiki Giei was unable to meet this requirement, by changing the wire diameter or pitch in the thickness direction, this requirement could be met. It is satisfying.

To be more specific, it is composed of a thick plate part that has a filter function and a thick plate part that does not have a filter A running part and is a coarse, low ventilation resistance part that aims to improve strength. A thin wire diameter linear extrusion and/or an integrally formed product with a dense layer pitch, and the main part of the strength improvement a is a thick wire diameter linear extrusion and/or a coarse layer pitch. By doing so, it becomes possible to respond.

(Claim 10) In addition to the large size, the cross-sectional shape of the linear extrudate can be modified to have an irregular cross-sectional shape, such as a star shape or a gear shape, to increase the surface area compared to large cross-sections, so that it can be used, for example, as a catalyst carrier. In this case, the reaction efficiency will be increased, or when used as a filter material, the collection rotation will be improved, and furthermore, it will be used as a highly efficient filter with less re-scattering of the fruit to be complemented.

(Claim ti) By increasing the lamination density at the outer periphery of the plate-shaped porous body, the strength can be further improved, and the porous body can be made to provide very effective /\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\visatom-by-component” properties.

(Claim 12) Next, when a porous body such as that of the present invention is installed as a filter or a catalyst carrier in various system piping channels, the flow velocity distribution in the piping is a physical phenomenon such that the flow velocity in the center is higher than that in the vicinity of the pipe wall. Since it is faster than the flow rate, this flow rate distribution is not an ideal condition from the viewpoint of the efficiency of the filter or the reaction efficiency of the catalyst, that is, from the viewpoint of effectively utilizing the entire surface of the filter. This flow rate distribution is forced to: J41, increasing the lamination density in the center of the porous body is beneficial in effectively using the entire surface of the porous body.

(Claim 13) By making the overall shape corrugated, a thin plate with high strength (
Mainly bending strength).

In this case, a thin plate is formed in advance and the thin plate is or
This can be easily achieved by placing it horizontally on a desired wavy mold while retaining its plasticity and press-molding it.

In addition, if the installation method shown in Fig. 13 is used, P
Although it is desirable that the dimension H be larger, various tests have shown that the maximum PH dimension that can be attached to a corrugated mold without cracking the plastic linear extrudate constituting the thin plate is about 100 mm. In addition, the pH is generally determined by the balance with the pH, and ideally it is 120 mm or less.

(Claim 14) By moving the receiving surface or the extrusion die in the lateral direction, one way or reciprocating, the spiral or corrugated material is laminated in the height direction, thereby producing a porous molded product consisting of multiple layers. be able to.

[Embodiments of the invention] Embodiments of the present invention will be described below based on the drawings.

(First example) First, a porous molded body was manufactured as shown in FIG.

In this example, a conventional extrusion die 2 shown in FIG. 14 was used as the extrusion die.

A viscoelastic material A made of an inorganic substance is extruded through a number of nozzle holes 5 provided in an extrusion die 2 to form a unit linear extrudate 8, and the unit linear extrudate 8 is vertically lowered to form a receiving surface. 14 in a spiral pattern.

In this example, by moving the receiving surface 14 or the extrusion die 2 in the lateral direction, one way or reciprocating, the spiral or corrugated material is laminated in the height direction (in the direction of arrow H) to form multiple layers. A porous molded body was manufactured.

The porous molded product thus produced is a plate-like porous molded product composed of a large number of i'ti-position linear drawn wire-like extrudates made of an inorganic substance, and the unit linear extrudates are plate-like In addition to forming continuous waveforms or loops with approximately equal pitch in a plane in a direction approximately perpendicular to the thickness direction of the porous molded body,
It is arranged so as to be joined or intertwined with at least one of the adjacent unit linear extrudates.

On the other hand, the appearance of the surface layer of the porous body according to this example is shown in FIG. 6, and its shape characteristics are as follows.

Linear extrudate cross-sectional diameter: 1.5mmφ Turning outer circumference size: 19mmφ Turning inner circumference size: 16mmφ Surface layer opening ratio: Approx. 60% In this example, a case where the unit linear extrudate forms a loop is shown, but the seventh It may also be wavy as shown in Figure (a). Also,
As shown in FIGS. 7(b) and 7(C), the loops may not overlap each other.

Further, in this example, the number of layers in the thickness direction is plural, but a single layer may be used depending on the use of the porous molded body.

(Second Example) Two types of perforated plates were prepared using the same method as in the first example: a perforated plate laminated in only one direction and a perforated plate in which adjacent corner layers are substantially orthogonal to each other in the thickness direction, and the bending strength was compared. I tried.

Material: Mixed sample of SiC and mullite Overall size: 50w x 100L x 20T Constituent wire diameter: 1.5 Overall porosity = 70% A three-point bending test was conducted with span 70II11.

The results are shown in Table 1. Note that the A direction and B direction in Table 1 are the directions shown in FIG.

Table 1 Three-point bending test results (Unit: kg/crn')
(Third Example) A thin strip plate laminated only in one direction was created, and -.
A corrugated plate was press-molded to the specifications shown in the figure, and one test piece was cut from the same flat plate to compare its high-temperature creep strength.

Material: Mullite test piece Overall size: 50X215X8 Wire diameter:
1.5mmφ Overall void volume ratio: 65% Test conditions Approximately 1
The specimen was held for a certain period of time, and the deflection δ of the center portion of the test piece that occurred during this time was measured (δ is the amount shown in FIG. 10).

The results are shown in Table 2. As shown in Table 2, it can be seen that the bending strength of the corrugated sheet is even greater.

Table 2 δ Expression (Fourth Example) A molded body having the following specifications was manufactured by the method shown in the first example.

Molded object specifications Material: Cordurite molded object overall size = 130 φ x 30 t (mm) Constituent wire diameter: 1.5 mm φ Molded object porosity: Approximately 70% The ventilation resistance of this molded object was measured using the device shown in Figure 11. . The results are shown in FIG. 12. FIG. 12 also shows the results for a molded article according to a conventional example (technique described in JP-A-58-116134).

As seen from this result, the ventilation resistance of the present invention was significantly lower despite the same porosity.

This difference is due to the difference in the aperture ratio of the surface layer and the uniformity of the surface layer and the openings.

The performance of the molded body according to this example is shown in Table 3 together with the conventional example.As can be seen from Table 3, the molded body according to this example has excellent ventilation resistance, filter function, bending test, thermal shock performance, porosity, It is superior to the conventional example in terms of uniformity of surface pores.

[Effects of the Invention] As described above, the present invention provides a porous body in which waveforms or loops arranged at approximately equal pitches are formed in a plane substantially perpendicular to the thickness direction of the plate-shaped porous body. This made it possible to create a porous body with uniform pores in the thickness direction. i.e. 1
In the porous body according to the present invention, uniform pores are always formed on the laminated surface, that is, on the inlet surface and the outlet surface when used as a filter. Also.

It has a high porosity.

The surface layer aperture ratio is significantly increased compared to the prior art.

In this way, by making a loop-shaped or wavy linear extrudate into a porous body formed in a plane substantially perpendicular to the plate thickness direction, it is possible to solve the problem in the plate thickness direction, which was a problem with the conventional technology. This is a porous material that has greatly improved the non-uniformity of pore size and low aperture ratio. In addition, in terms of strength, since the skeleton is made of a linear extrudate with a uniform cross section, the skeleton is partially thin, or the skeleton formed is Although there was a problem of easy chipping due to no external pressure being applied, this porous material has been improved in these areas as well.

[Brief explanation of drawings]

1 to 4 are conceptual diagrams showing the joined state of unit linear extrudates, FIG. 5 is a perspective view for explaining the production of a molded body, and FIG. 6 is a molded body according to an example. FIG. FIG. 7 is a side view showing an example of the shape of a unit linear extrudate. FIG. 8 is a perspective view showing the direction of movement of the extrusion die in the second embodiment, FIG. 9 is a perspective view of a molded product having a corrugated shape as a whole, FIG. 1
Figure 1 is a conceptual diagram showing a ventilation resistance measuring device, Figure 12 is a graph showing the relationship between wind speed and pressure loss, Figure 13 is a perspective view of a molded body to explain the preferred plate thickness, and Figure 14 is a conventional FIG. 15 is a sectional view showing a conventional molded body. Figure 5 Figure 6 Figure 1 Figure 3 Figure 7 (a) (b) (c) Figure 8 Figure 9 Figure 11 Figure 12 □1st generation CM/S)

Claims (15)

[Claims] (1) A molded product composed of a large number of linear extrudates made of an inorganic substance, in which the linear extrudates have a wave shape or a loop in a plane substantially perpendicular to the thickness direction of the molded product. A porous molded body characterized by forming a porous molded body. (2) The porous molded article according to claim 1, wherein the linear extrudate is arranged so as to be joined or intertwined with at least one other adjacent linear material. (3) Claim 1, wherein the molded body has a plate shape;
The porous molded article according to item 2. (4) The porous molded article according to claims 1 to 3, wherein the inorganic substance is a non-porous inorganic substance. (5) The porous molded article according to claim 4, wherein the inorganic substance is a porous inorganic substance. (6) The porous molded body according to any one of claims 1 to 5, wherein the porous molded body has a plurality of layers in the thickness direction. (7) The porous molded article according to claim 6, wherein each layer adjacent in the thickness direction has linear extrudates arranged in directions substantially orthogonal to each other. (8) The porous molded body according to claim 6 or 7, wherein the wire diameter of the linear extrudate is changed for at least one layer of the porous molded body. (9) A porous molded article according to claim 6 or 7, in which the pitch of the corrugated or looped linear extrudates is different in the thickness direction of the porous molded article. (10) The porous molded article according to any one of claims 1 to 9, wherein the linear extrudate has an irregular cross-sectional shape. (11) The porous molded body according to any one of claims 1 to 10, wherein the laminated density of the outer peripheral portion of the porous molded body is increased. (12) The porous molded body according to any one of claims 1 to 10, wherein the laminated density of the central portion of the porous molded body is increased. (13) The porous molded body according to any one of claims 1 to 12, wherein the overall shape of the porous molded body is a corrugated plate shape. (14) A viscoelastic material made of an inorganic substance is extruded through a number of nozzle holes provided in an extrusion die to form a unit linear extrudate, and the unit linear extrudate is vertically lowered onto a receiving surface. 1. A method for producing a porous molded article, which is characterized in that it is deposited in a spiral or wavy shape. (15) A porous molded body according to claim 12, in which spiral or wavy unit linear extrudates are laminated in the height direction by moving a receiver or an extrusion die laterally one way or back and forth. Production method.