JPH0653627B2 - Method for producing porous inorganic molded body - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a method for producing a porous inorganic molding which has a large number of pores inside, is lightweight, and has excellent insulation properties.

[Conventional technology]

Conventionally, cement is mixed with reinforcing materials such as wood chips and pulp fiber, and a raw material mixture is further formed by mixing expandable plastic beads, and the mixture is heated to foam the expandable plastic beads in the raw material mixture. A porous cement board that is lightweight and has insulation properties such as heat insulation and soundproofing by melting a large number of pores in the molded body by melting the plastic beads foam particles obtained by foaming the plastic beads A manufacturing method is provided (JP-A-54-157125, JP-B-63-1276).

[Problems to be Solved by the Invention]

However, when wood pieces are used as the reinforcing material, there is almost no entanglement among the wood pieces, so the strength of the product obtained is not sufficient unless the pressing force during molding is increased to increase the product density, and When pulp fibers are used as the material, the density of the cement-pulp fiber mixture is increased, and foaming of the expandable plastic beads is suppressed.

[Means for Solving the Problems]

The present invention, as a means for solving the above conventional problems,
A mixture of a wood fiber bundle, curable inorganic powder, and expandable plastic beads, which are made bulky by branching and / or bending and / or bending, is molded into a predetermined shape and the foamed by heating. The present invention provides a method for producing a porous inorganic molded body which foams a flexible plastic bead and cures the curable inorganic powder.

The present invention is characterized by using a wood fiber bundle as a reinforcing material. And in the present invention, the wood fiber bundle is a bundle of wood single fibers, and the wood fiber bundle is made bulky by branching and / or bending and / or bending. In order to produce a wood fiber bundle that is made bulky by branching and / or bending and / or bending, the wood is immersed in a chemical solution such as caustic soda, sodium sulfite, calcium sulfite, or the wood is steamed. By heating, or by using the above-mentioned chemical solution immersion and steam heating together, swelling without completely dissolving lignin, hemicellulose, resin, etc., which plays a role of a binder of wood single fibers contained in wood It is defibrated by allowing the binder to remain after it has been retained, and therefore does not inhibit the curing reaction of the curable inorganic powder such as cement, and the lignin is removed from the binder by almost completely removing it. It has a larger diameter than fine pulp fibers. And the diameter of the wood fiber bundle is about 0.1 to 2.0 mm
And the length is in the range of about 2-35 mm, preferably in the range of 10-30 mm.

When the wood fiber bundle is branched, the diameter of the wood fiber bundle is within the range of about 0.1 to 2.0 mm assuming that the wood fiber bundle is not branched, and the wood fiber bundle is curved and / or bent. If so, the length refers to the actual length of the wood fiber bundle, not the distance between the ends.

The wood fiber bundle is bulky due to the above size and shape, but its bulk specific gravity is in the range of about 0.03 to 0.05 g / cm ³ . Here, the volume specific gravity is 8 cm in inner diameter and the volume of 2000 ml is filled with 2000 ml of the absolutely dried wood fiber bundle, and the whole weight is measured, and the weight of the whole graduated cylinder is subtracted from the total weight to obtain the wood fiber bundle. Of the graduated cylinder is placed on the wood fiber bundle filled with a disk that fits exactly into the inner diameter of the graduated cylinder, a weight is placed on the disk, and a weight of 1 kg is applied to the wood fiber bundle. It is determined by measuring the volume of the wood fiber bundle and dividing the weight (g) of the wood fiber bundle by the volume (cm ³ ).

In order to make the wood fiber bundle bulky by branching and / or bending and / or bending, the degree of swelling and defibration of the binder is adjusted. The defibration is performed, for example, by a grinding disc, and the degree of defibration is adjusted by adjusting the disc gap of the grinding disc.

Curable inorganic powder used in the present invention, cement, inorganic powder that hardens by hydration reaction such as gypsum, cement, calcium-containing inorganic powder such as gypsum and silica sand, silica stone powder, silica fume, shirasu balloon and the like. A mixed inorganic powder that hardens by a calcium silicate reaction such as a mixture with a silicic acid-containing inorganic powder, an inorganic powder that hardens due to crystal rearrangement of magnesium carbonate, and the like, and a desirable curable inorganic powder for the present invention is cement and silica sand. It is preferable that the content of cement in the mixture is 30 to 70% by weight. By mixing the cement and the silicic acid-containing inorganic powder in the above ratio, the hardening of the curable inorganic powder due to the calcium silicate reaction proceeds very smoothly.

The wood fiber bundle and the curable inorganic powder are mixed and used as a raw material for an inorganic molded body. In the case of the dry manufacturing method, the raw material mixture is sprayed on a template, and the wood fiber bundle is usually added to the raw material mixture in an amount of about 5 to 25% by weight.

Further, inorganic fillers such as perlite, bentonite, blast furnace slag, rice ash, fly ash, diatomaceous earth, etc., organic fillers such as synthetic resins, synthetic resin foams, wood chips, wood flour, etc. may be added. Of these components, perlite is desirable as an additive component because it reduces the weight of the product and imparts lubricity to the raw materials to facilitate mixing. The perlite is usually contained in the raw material in an amount of 5 to 15% by weight. When the curable inorganic powder is cement, a curing accelerator such as magnesium chloride, calcium chloride, aluminum sulfate, water glass, or aluminate may be added. The hardening accelerator is usually added in an amount of 2 to 4% by weight with respect to cement.

The above examples do not limit the present invention.

The expandable plastic beads used in the present invention are beads of thermoplastics such as polyethylene, polypropylene and polystyrene impregnated with a volatile foaming agent such as propane, butane, pentane and petroleum ether. In the present invention, the expandable plastic beads may be added to the raw material mixture as they are, but usually, the expandable plastic beads are heated to about 95 to 105 ° C. and pre-expanded and added to the raw material. The amount of the expandable plastic beads added is usually 0.5 to 5% by weight in the raw material mixture. When the amount of the expandable plastic beads added is 0.5% by weight or less, the case of voids in the molded article is reduced and the insulation property becomes insufficient, but when it is 5% by weight or more, the proportion of voids is increased. It becomes too large and the strength of the molded product decreases.

The above raw material mixture is sprinkled on a template to form a mat, but in the continuous production method, a large number of the templates are placed on a belt conveyor. The raw material mixture sprinkled on the template is slightly pressed by a roll or the like if desired, and the mat is then pressure-hardened in the presence of water to be molded into a desired shape. The amount of water added is usually 3 in the above raw material mixture.
0 to 45% by weight is included. Clamping conditions are usually 10 to 20 kg / cm ^{2 of} pressure, temperature of 60 to 80 ° C., time of 20
It is performed in about 30 hours, and heating is usually performed with steam. The pressing is performed by sandwiching the mat between two mold plates, but the mold plate surface may be provided with a predetermined shape, an uneven pattern or the like.

The inorganic molded body of the present invention is usually molded into a plate shape, but may be molded into a block shape or the like if desired.

The inorganic molded body of the present invention is cured in an autoclave if desired after compression hardening. Curing conditions are usually pressure of 10-2
It is 0 kg / cm ² , the temperature is 160 to 180 ° C., and the time is 5 to 10 hours.

By the autoclave curing, the expandable plastic beads are completely expanded, and at the same time, the plastic foam particles formed by the expansion of the expandable plastic beads are melted and the foaming agent in the cells escapes to the outside, and the plastic foam is It rapidly shrinks to form a large number of pores inside the inorganic molded body. A plastic coating layer attributed to the plastic foam particles is formed on the inner wall surface of the pores.

The above-mentioned autoclave curing is not always essential, and after compression, the expandable plastic beads may be foamed by heating at normal pressure, and then natural curing may be performed. In addition to the dry manufacturing method, pressing molding or the like may be applied, or the foamable plastic beads may be foamed simultaneously with molding by heating during molding.

In this way, the porous inorganic molded body of the present invention is obtained.

[Action]

Since the wood fiber bundle used in the porous inorganic molded body of the present invention is made bulky by branching and / or bending and / or bending, it is mixed with a curable inorganic powder or the like to form a raw material mixture. In the state, the fiber bundles are entangled with each other through a certain distance, but since the fiber bundle has a diameter larger than that of a wood single fiber such as pulp fiber, it has a certain degree of rigidity and is entangled in a thread-like shape. Instead, the curable inorganic powder, expandable plastic beads, and the like are held between the fiber bundles entwined in this way. The rigidity of the fiber bundles described above serves to maintain the distance between such fiber bundles and maintain bulkiness. Therefore, since such a bulky state is maintained even when the molding pressure is exerted, foaming of the expandable plastic beads due to heating during molding or after molding is less likely to interfere with the fiber bundle,
The foaming is done smoothly. Further, when the dry production method is applied to the production of the porous inorganic molded body of the present invention, the raw material mixture can be loosened by mechanical stirring or the like, and the raw material mixture can be easily dispersed evenly on the template. However, after spraying, as described above, the raw material components such as curable inorganic powder and expandable plastic beads are entangled by the entanglement of the wood fiber bundle through a certain distance.
It is possible to form a mat which does not lose its shape and in which the expandable plastic beads can be smoothly foamed.

Also in the product, the porosity based on the plastic foam obtained by the smooth foaming of the expandable plastic beads in the matrix and the fiber bundles of the wood fiber bundle are firmly entangled with each other through a certain distance as described above. That is, the specific reinforcing effect synergizes with each other to provide a porous inorganic molded body having a small specific gravity and therefore a light weight, a high insulation property and a high strength. Further, in the production of the porous inorganic molded body of the present invention, autoclave curing is carried out after pressing, but the foaming and melting of the expandable plastic beads and the curing reaction of the curable inorganic powder during the autoclave curing are almost complete. To end. Unlike conventional wood fibers, the fiber bundle of the present invention is defibrated without dissolving the lignin, hemicellulose, resin, etc., which are the curing inhibitors of cement by shortening the cooking time during defibration, and thus cured. The hardening of the water-soluble inorganic powder proceeds smoothly without being hindered. Therefore, a plastic coating attributed to the foamed melt of the expandable plastic beads is applied to the inner wall surface of the pores in the product, and a product having low porosity but low water permeability and therefore high freeze resistance is obtained, and the product is In the above, the curing reaction of the curable inorganic powder hardly progresses, and the dimensional change of the product due to the curing reaction is avoided.

〔The invention's effect〕

Therefore, in the present invention, it is possible to obtain a porous inorganic molded body that is lightweight, rich in insulation properties, has high strength, and has extremely good dimensional stability, and to manufacture the porous inorganic molded body by a dry manufacturing method. It is possible and it is easy to obtain a homogeneous product by the dry manufacturing method. Further, since the wood fiber bundle of the present invention has a large reinforcing effect, a porous molded product having a sufficiently large strength can be obtained even when the amount of addition is 25% by weight or less, and therefore a porous molded product excellent in nonflammability can be obtained. .

〔Example〕

 Examples 1-10 The following composition is mixed with a mixer.

Cement 46% by weight Silica sand 28 〃 Perlite 10 〃 Wood fiber bundle 10 〃 Expandable polystyrene beads (pre-expanded product) 3 〃 Aluminum sulfate 3 〃 The above-mentioned wood fiber bundle has branching and / or bending with the following dimensions and bulk specific gravity / Or use a bent one.

Water was added to the above mixture to make the water content 40% by weight, and then the mixture was sprayed on the lower mold plate to form a mat having a thickness of 55 mm. The upper mold plate was brought into contact with the mat, and the pressure was 10 kg / c after press molding.
Press-cure and cure at m ² and temperature of 70 ° C. for 25 hours. The obtained molded body was a plate-shaped body having a thickness of 15 mm, and the molded body was then placed in an autoclave at a pressure of 15 kg / cm ² and a temperature of 165.
After being cured at 7 ° C. for 7 hours, the expandable polystyrene beads in the molded product foam and then melt.

In this way, porous molded bodies 1 to 10 are obtained.

Comparative Examples 1 to 8 In the compositions of Examples 1 to 10, the wood fiber bundles having the following dimensions and bulk specific gravity, which were branched and / or curved and / or bent, were used, but otherwise the porous molding was performed in the same manner. Get bodies 11-18.

The spraying workability, the deformability of the mat, and the specific gravities, bending strengths and freeze resistance of the molded products 1 to 18 of the above Examples and Comparative Examples were measured. The results are shown in Tables 1 and 2.
The shape of the mat is 2 cm on the lower template on which the mat is placed.
The stroke is checked for the shape of the mat when it is moved up and down three times in a cycle of 1 second. Freezing resistance is ASTMC-
A freeze-thaw test is performed by the 666B method, and the state of the molded article after 300 cycles is examined.

Referring to Table 1 above, an average diameter of 0.1 to 2.0 mm and a length of 10
Examples 1 to 30 with a bundle of wood fibers in the range of 30 mm and branched and / or curved and / or bent
It is understood that No. 10 is easy to loosen the mixture, easy to spread and does not lose the shape of the formed mat, and that the above wood fiber bundle is extremely useful for the dry manufacturing method.
On the other hand, Comparative Example 1 using a wood fiber bundle having an average diameter of 0.1 mm or less
And 2, or Comparative Examples 7 and 8 using the wood fiber bundles having an average length of 30 mm or more, the entanglement of the wood fiber bundles is likely to become a thread-like shape, thus causing a problem in spraying workability. Further, Comparative Examples 3 and 4 using the wood fiber bundles having an average diameter of 2.0 mm or more, or Comparative Examples 5 and 6 using the wood fiber bundles having an average length of 10 mm or less are not sufficiently entangled with the wood fiber bundles. Inferior strength. Therefore, when the wood fiber bundles of Comparative Examples 1 to 8 are used, the dry manufacturing method is difficult to apply.

Further, referring to Table 2 above, the molded bodies 11 and 12 using the wood fiber bundle having an average diameter of 0.1 mm or less have a large specific gravity of 1 or more, and the molded body 13 using the wood fiber bundle having an average diameter of 2.0 mm or more. And 14, or the molded bodies 15 and 16 using the wood fiber bundle having an average length of 10 mm or less, the entanglement of the wood fiber bundle is insufficient and the bending strength is reduced. Further, even if the average length of the wood fiber bundle is 30 mm or more, uneven distribution occurs as in the case of the molded bodies 17 and 18, and as a result, a molded body having a uniform structure cannot be obtained and the bending strength is lowered. . Further, in the molded body 12, even if it has a high specific gravity, the freezing resistance is slightly inferior because the foam is slightly crushed, and in the molded bodies 13 and 14, the specific gravity is low, the internal porosity is large and the freeze resistance is poor. ing.

Example 11 A branched and curved wood fiber bundle having an average diameter of 1.0 mm, an average length of 18 mm, and a bulk specific gravity of 0.040 g / cm ³ was mixed with the following composition by a mixer.

Cement 48% by weight Rice ash 20 〃 Diatomaceous earth 10 〃 Wood fiber bundle 15 〃 Expandable polystyrene beads (pre-expanded product) 2 〃 Calcium chloride 5 〃 Water content of the above mixture was adjusted to 35% by weight It is sprinkled on the plate to form a mat with a thickness of 75 mm, the upper mold plate is brought into contact with the mat, and after press molding, the pressure is 15 kg / cm.
^2. Press-cure for 30 hours at a temperature of 75 ° C. The obtained molded body was a plate-shaped body having a thickness of 20 mm, and the molded body was then placed in an autoclave at a pressure of 17 kg / cm ² and a temperature of 170.
It is aged at ℃ for 8 hours.

In this way, the porous molded body 19 is obtained.

Comparative Example 9 An average diameter of the wood fiber bundle in the composition of Example 11 was 0.08 mm,
Pulp fiber 7 having an average length of 18 mm and a bulk specific gravity of 0.059 g / cm ³ ;
A molded body 21 is manufactured in the same manner except that the polyester fiber having a thickness of 2 denier and the length of 15 mm is replaced with 3 parts by weight of the mixed fiber, but the pulp fiber and the polyester fiber are entangled in a string in the mixture. As compared with Example 11, it was difficult to uniformly spread the mixture on the lower template.

Comparative Example 10 A molded product 22 is manufactured in the same manner as in Example 11 except that the wood fiber bundle is replaced with wood chips having a thickness of 0.4 to 1.0 mm and a bulk specific gravity of 0.095 g / cm ³ which pass through a 10 mm mesh. Since the wood chips had almost no entanglement in the mixture, it was easy to uniformly mix them by mechanical stirring, and it was easy to uniformly spread the mixture on the lower template.

Test The shape deformability of the mats of Examples 11 and 12 and Comparative Examples 9 and 10 and the specific gravity and bending strength of the molded bodies 19 to 21 were measured. The results are shown in Table 3.

According to Table 3, Example 11 does not lose the shape of the mat,
In Comparative Example 9, even if the polyester fibers were mixed, some deformation was still observed. Further, the molded body of Example 11 is obviously lighter in weight and stronger than the molded bodies 20 and 21 of Comparative Examples 9 and 10.

Moreover, the mechanical strength of the molded body 21 is extremely weak and it cannot be practically used. In order to have a strength equivalent to that of Example 11, that is, a bending strength of about 70 kgf / cm ^{2, the} amount of wood chips added was about 30% by weight, and the clamping pressure was 30 kg /
It is necessary to raise it to about cm ² . However, if the amount of wood chips added is increased, the incombustibility of the molded product deteriorates, and if the clamping pressure is increased, the specific gravity of the molded product increases to about 1.3 and becomes heavier. Moreover, high strength products cannot be obtained.

Comparative Example 11 Instead of the wood fiber bundle of Example 1, an unbranched linear wood fiber bundle having an average diameter of 0.10 mm, an average length of 20 mm and a bulk specific gravity of 0.054 g / cm ³ was used, and the same procedure as in Example 1 was performed. The obtained molded body 22 has a specific gravity
It has a bending strength of 1.16 g / cm ³ and a bending strength of 60 kgf / cm ² , and has a specific gravity higher than that of the molded product 1 shown in Table 2, but is inferior in strength.

Comparative Example 12 Instead of the wood fiber bundle of Example 5, a branched and / or curved and / or bent wood fiber bundle having an average diameter of 2.3 mm, an average length of 20 mm and a bulk specific gravity of 0.028 g / cm ³ is used. A molded body 23 obtained by using the same method as in Example 5 has a specific gravity of 0.86 g / c.
It had m ³ and a bending strength of 56 kgf / cm ² , which was inferior to the molded product 5 shown in Table 2.

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C04B 22:14 2102-4G 24:00 2102-4G 22:12) 2102-4G

Claims (4)

[Claims] 1. A mixture of a wood fiber bundle, which is made bulky by branching and / or bending and / or bending, curable inorganic powder, and expandable plastic beads, is molded into a predetermined shape, and A method for producing a porous inorganic molded body, which comprises heating to foam the expandable plastic beads and curing the curable inorganic powder. 2. A template comprising a mixture of a wood fiber bundle, which is made bulky by branching and / or bending and / or bending, curable inorganic powder, and expandable plastic beads. A method for producing a porous inorganic molded article, which comprises forming a mat, pre-curing the mat under pressure in the presence of water, and then curing the foamed plastic beads by curing by heating in an autoclave and curing the foamed plastic beads. 3. The wood fiber bundle has a diameter of 0.1 to 2.0 mm and a length of 2.
The method for producing a porous inorganic molded body according to claim 1 or 2, wherein the porous inorganic molded body has a diameter of ˜35 mm. 4. The bulk specific gravity of the wood fiber bundle is 0.03 to 0.05 g / cm.
^The method for producing a porous inorganic molded body according to claim 1 or 2, which is in the range of ³