JPH0415317B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for producing paper with a high content of inorganic powder,
More specifically, the present invention relates to a method for continuously producing powder-containing paper that has a very uniform texture and a high yield of inorganic powder by applying wet papermaking technology. (Conventional technology) Aluminum hydroxide, talc, kaolinite,
Inorganic substances such as zeolite and sepiolite have many excellent properties such as heat insulation, heat resistance, nonflammability, adsorption, chemical stability, and electrical insulation, and attempts are being made to apply and utilize these properties. is being actively pursued in all areas. In particular, in recent years, these inorganic materials have been molded into sheet shapes for applications that could not be used in powder form, such as insulation materials, high-temperature sealing materials, reinforcing materials, heat-resistant packing materials, sound-deadening materials, filter media, and heat-resistant filters. A lot of research is being carried out to use inorganic materials, separators, wire coating materials, catalyst carriers, noncombustible building materials, etc., and various methods of forming these inorganic materials into sheets have also been proposed. In particular, the wet papermaking method used in the paper manufacturing industry is attracting attention from various quarters as it can produce sheets with relatively uniform thickness and density. However, it has been extremely difficult to continuously form these inorganic materials, especially powder materials, into sheets by simply applying the commonly used wet papermaking method. In other words, unlike cellulose fibers obtained from wood etc., inorganic powder is very fine particles and has a high specific gravity. These inorganic powders cannot be made into a sheet due to the following reasons. Therefore, several methods have been proposed for forming these inorganic powders into sheets using a wet papermaking method. One method is to add a fibrous substance and a coagulant to inorganic powder to make paper. For example, Japanese Patent Publication No. 52-5328 discloses that 50-98% by weight of inorganic fine powder and 50-2% by weight of pulp are used. A method is disclosed in which an amphoteric surfactant is added to a slurry to adsorb and aggregate inorganic fine powder on the fibrous surface, and a sheet-like molded product is obtained by a normal wet papermaking method. However, although this method can produce some sheet-like products, it has not been possible to continuously obtain sheets with a high yield of inorganic fine powder and a uniform texture. That is,
The agglomerated flocs of inorganic fine powder and pulp produced by the amphoteric surfactant in the storage tank will settle immediately when stirring is stopped, and although sedimentation can be prevented if stirring is continued, the flocs will be destroyed by the impact of stirring. Otherwise, the flocs are fragmented into small flocs, and it is extremely difficult to supply the flocs that maintain a constant shape from the storage tank to a flow box or the like. Further, in the conveying system from the storage tank to the paper making wire, agglomerated flocs were deposited along the way, making it impossible to always supply a constant amount of the agglomerated slurry onto the paper making wire. Furthermore, the supply onto the paper-making wire is only by the force of the water flow, and the coagulated slurry with high specific gravity tends to stagnate under the water flow and cannot flow smoothly, forming a paper layer with a uniform texture. It was difficult. Further, another method is proposed in Japanese Patent Publication No. 30399/1983. That is, as a method for producing a sheet-like product with uniform thickness and density, paper stock in which fine inorganic powder has been adsorbed and aggregated is passed through a strip-shaped nozzle that reciprocates linearly and has a gap of a constant slit width into a papermaking tank. A method for dispersing and making paper is disclosed. Although it is true that this method yields sheets with a relatively uniform texture, the production method is batch-based, making it impossible to produce sheets continuously and is extremely inefficient. It was hot. (Problems to be Solved by the Invention) The present invention solves the drawbacks of conventional methods for producing inorganic powder sheets, namely, the yield of inorganic powder during papermaking is poor.
Problems include the fact that the sheet has a low content of inorganic powder, is difficult to form, and has uneven density and thickness, and as a result, paper breaks are likely to occur and continuous paper making is difficult. The purpose is to solve the problem. (Means for Solving the Problem) As a result of intensive study, the present inventors have determined that the agglomeration of unagglomerated slurry mainly composed of inorganic powder can be carried out from a storage tank to a paper-making wire instead of the conventional storage tank. It has been found that even if the process is carried out during the flow of the mixture, a uniform floc can be obtained. Furthermore, we conducted repeated studies on a method of feeding the coagulated flocs to the papermaking wire without destroying them, and finally completed the present invention. FIG. 1 of the drawings is a schematic process diagram of an embodiment of the present invention. The gist of the present invention will be explained based on the drawings: (1) The unagglomerated slurry 4 mainly composed of inorganic powder dispersed in the storage tank 1 is transferred to the feed pipe 7 leading from the storage tank 1 to the flow box 13. By adding a flocculant during the flow through the medium, flocculation occurs, forming flocs 1.
(2) The agglomerated flocs 10 are supplied to the flow box 13 and mixed with carrier water 14 supplied from near the bottom of the flow box at a position lower than the feed pipe 7 attached to the flow box 13. (3) Next, the agglomerated flocs overflowing from the flow box 13 are supplied onto the paper making wire 16 via a smooth surface flow plate 15 with an inclination angle of 5 to 45 degrees from the overflow part to the paper making wire 16, The objective is to obtain paper with a high content of inorganic powder by papermaking. In the present invention, the unagglomerated slurry mainly composed of inorganic powder is one in which inorganic powder, fibrous substances, organic binders, inorganic binders, etc. are dispersed in water, and other additives are added as necessary. Agents can also be blended. The inorganic powder in the present invention refers to non-metallic inorganic matter,
Powder or fine fibers of metals, insoluble salts, etc., such as silica stone, silica sand, diatomaceous earth, bauxite,
Sericite, bentonite, acid clay, chinastone, waxite, feldspar, limestone, wollastonite, gypsum, dolomite, magnesite, talc, asbestos, alumina, magnesia, zirconia, titanium oxide, spinel, synthetic cordierite, synthetic mullite , TiC, ZrC,
Carbide such as VC, TaC, SiC, _B4C , TiN,
Nitrides such as BN, TaN, _Si3N4 , _AlN , graphite,
Ferrous oxide, ferric oxide, lead oxide, zinc oxide, nickel oxide, beryllium oxide, cupric oxide, cobalt oxide, manganese dioxide, titanium dioxide, barium carbonate, manganese carbonate, magnesium carbonate, calcium carbonate, barium sulfate , magnesium hydroxide, aluminum silicate, magnesium silicate,
Synthetic zeolite, natural zeolite, silica gel,
Examples include powders or fine fibers of sepiolite, potassium titanate, barium titanate, activated carbon, graphite, amorphous silica, etc., and one or more of these is selected depending on the desired performance. The fibrous substance is added for the purpose of improving the separation of the wet paper from the papermaking wire during papermaking or imparting the necessary strength to the sheet, and is at least 0.5 parts by weight or more by weight of 40 parts by weight per 100 parts by weight of the inorganic powder. It is preferable that less than 1 part is added. Such fiber materials include wood pulp, linter, animal and vegetable fibers such as cotton, silk, hemp, and mulberry; synthetic fibers such as polyester, polyamide, and polyolefin; modified cellulose fibers such as regenerated cellulose fibers and microfibrillated cellulose; and glass. Fibers, inorganic fibers such as rock wool, etc. can be used. In addition, the organic binder increases the bonding strength of inorganic powders and fibrous substances, gives the sheet strength, flexibility, and abrasion resistance, and makes the sheet easier to handle. It is preferable to add at least 0.1 parts by weight to 10 parts by weight or less. As such an organic binder, known synthetic rubber latex, synthetic resin emulsion, water-soluble polymer, etc. can be used. Furthermore, an inorganic binder such as colloidal silica, alumina sol, titania sol, etc. can be blended for the purpose of increasing the binding strength of the inorganic powder, fibrous material, etc., and increasing the proportion of inorganic matter in the obtained sheet. Although the present invention does not limit the blending ratio of inorganic powder, fibrous material, organic binder, inorganic binder, etc., according to the method of the present invention, a sheet with an inorganic powder content of 99.5% can be produced. It is also possible to make paper. The present invention will be explained below based on the drawings. An inorganic powder, a fibrous substance, an organic binder, an inorganic binder, and the like are each put into a storage tank 1 and adjusted to a non-agglomerated slurry 4. Alternatively, part or all of it may be prepared elsewhere and then transferred to a storage tank. The storage tank in the present invention is a container equipped with a stirring device that can uniformly and continuously disperse the unagglomerated slurry, and the shape of the container, the type of the stirring device, etc. are not limited. Unagglomerated slurry 4 uniformly dispersed in storage tank 1
is agglomerated during its flow, and is transferred to flow box 1.
3. The unagglomerated slurry 4 is supplied to the flow box 3 through a feed pipe 7, but in the middle of the feed pipe 7 there is another feed pipe for supplying a flocculant 9 to the feed pipe. The unagglomerated slurry is flocculated in the feed pipe by a predetermined amount of flocculant supplied via the metering pump 3', valve 5', and flow meter 6, and flocculated flocs 10
is formed. Furthermore, it is supplied to the flow box 13. The flocculant may be added in one step or in two steps. In the present invention, the flow box means to uniformly mix the coagulated flocs 10 flown from the storage tank and the carrier water 14 consisting of white water and fresh water without destroying the flocs, and to distribute a certain amount of the flocs at an angle of inclination. It is a device for overflowing onto a flow plate 15 having a smooth surface, and its shape is not particularly limited as long as it has these functions. It is preferable that a stirring device 12 is provided as a means for uniformly mixing the coagulated flocs and the carrier water, and it is more preferable that the stirring device 12 be able to freely change the stirring speed. Further, the carrier water needs to be supplied from near the bottom of the flow box 13, which is lower than the feed pipe 7 attached to the flow box 13.
This prevents the flocs from settling and facilitates the mixing of the flocs and the carrier water. The agglomerated flocs overflowing from the flow box 13 are then fed onto the papermaking wire 16 through a flow plate 15 with an inclined angle and a smooth surface. In the present invention, the inclination angle from the overflow part of the flow box 13 to the paper making wire 16 is 5 to 5.
It is necessary to use a 45 degree smooth surface flow plate. The flow plate serves to supply the agglomerated flocs onto the papermaking wire uniformly, especially evenly in the width direction of the papermaking wire. The components of coagulated flocs are mostly inorganic substances and have a high specific gravity.If the conventional feeding method from the flow box to the papermaking wire is used, the coagulated flocs will accumulate on the way, and the coagulated flocs will not be uniformly transferred to the papermaking wire. Cannot be supplied above. The material and shape of the flow plate are not limited as long as the surface is smooth. If the surface is not smooth, for example if it is uneven, when the agglomerated flocs pass through the surface, they will accumulate on the uneven parts and will eventually form into lumps and be fed onto the paper making wire, resulting in a high powder content with good formation. Paper is no longer available. The agglomerated flocs thus fed onto the papermaking wire are then dewatered by suction and, if necessary, dried to produce paper with a high content of inorganic powder. Example 1 97 parts by weight of aluminum hydroxide powder (parts by dry weight, the same applies hereinafter), 3 parts by weight of hemp fiber, 5 parts by weight of polyacrylic acid ester emulsion, and 3000 parts by weight of water were mixed, and the mixture was prepared as shown in FIG. The slurry was poured into a storage tank 1 and constantly stirred with a rotary blade 2 and circulated with a centrifugal pump 3 to prepare a uniformly dispersed non-agglomerated slurry 4. Then, the valve 5 was opened while checking with the flow meter 6 so that the amount of unagglomerated slurry 4 supplied was a specified amount, and the unagglomerated slurry 4 was flowed into the feed pipe 7. At the same time, a fixed amount of the cationic polyacrylamide polymer flocculant, which has been uniformly dissolved in advance, is injected into the feed pipe 7 using the metering pump 3' into the dissolution tank 8, which is separate from the storage tank 1. Unagglomerated slurry in 4
were agglomerated to form an agglomerated floc 10. Further, an anionic polyacrylamide fixing agent 11 was injected from another feed pipe to stabilize the agglomerated flocs 10. The agglomerated flocs 10 generated in the feed pipe 7 are transferred to a flow box 1 equipped with a variable speed rotary stirrer 12.
A constant amount of carrier water 14 supplied from the bottom of the flow box 13 is mixed uniformly with the rotating speed of the rotary stirrer 12 so as not to destroy the flocs 10, and then the flow box 13 is heated. 13, a certain amount overflowed. Next, the agglomerated flocs 10 overflowing from the flow box 13 are flow-diffusion-supplied onto the paper-making wire using a flow plate 15 with a smooth surface extending from the overflow part to the paper-making wire at an angle of 15 degrees, and are further dehydrated and dried. Basis weight 820
g/m ² aluminum hydroxide paper was produced continuously. Example 2 87 parts by weight of aluminum hydroxide powder, 10 parts by weight of alumina fiber, 3 parts by weight of hemp fiber, 5 parts by weight of polyacrylic acid ester emulsion, and 3000 parts by weight of water were charged into storage tank 1. Aluminum hydroxide paper of 610 g/m ² was continuously produced in the same manner. Typical physical properties of the aluminum hydroxide paper obtained in Examples 1 and 2 are shown in the table. As shown in No. 1, all of the sheets had a high yield of inorganic powder, had excellent formation and strength, and were very easy to handle.

[Table] Comparative Example (Production of paper with high aluminum hydroxide content according to conventional example) In the storage tank 21 shown in Fig. 2, 97 parts by weight of aluminum hydroxide powder, 3 parts by weight of hemp fiber, and 5 parts by weight of polyacrylic acid ester emulsion were added. After dispersing the mixture uniformly by rotating the rotary blade 22, a cationic polyacrylamide fixing agent was added to form an agglomerated floc 23 in the storage tank 21. Next, the valve 24 is opened and the agglomerated flocs 23
into the flow box 26 through the feed pipe 25,
After mixing with the carrier water 27, an attempt was made to make paper by overflowing from the flow box 26 onto the paper making wire 28, but the flow of coagulated flocs into the white water resulted in a significantly poor yield, and formation could not be achieved, resulting in paper breakage. This occurred frequently and paper could not be made continuously. (Effects) As described above, the present invention has made it possible to continuously produce high-inorganic powder content paper with high yield and excellent formation. Furthermore, by selecting various inorganic powders depending on the purpose, insulation, heat resistance, nonflammability, adsorption,
By taking advantage of many excellent properties such as chemical stability and electrical insulation, it is possible to produce paper with a high content of inorganic powder that can be used in a wide range of applications.

[Brief explanation of drawings]

Figure 1 is a schematic process diagram of one embodiment of the present invention;
The figure shows a schematic process diagram of a conventional example. 1 and 21 are storage tanks, 2 and 22 are rotating blades, 2' is a stirrer, 3 is a centrifugal pump, 3' is a metering pump, 4
is unagglomerated slurry, 5, 5', 24 are valves, 6
is a flow meter, 7 and 25 are feeding pipes, 8 is a dissolution tank,
9 is a flocculant, 10 is a flocculating floc, 11 is a fixing agent, 12 is a variable rotation stirrer, 13 and 26 are flow boxes, 14 and 27 are carrier water, 15 is a flow plate with a smooth surface, 16 and 28 are paper making wires,
23 indicates agglomerated flocs, respectively.

Claims (1)

[Scope of Claims] 1. A flocculant is added to the unagglomerated slurry 4 mainly composed of inorganic powder dispersed in the storage tank 1 while it is flowing through the feed pipe 7 from the storage tank 1 to the flow box 13. 2. Supplying the flocculated flocs 10 to the flow box 13 from near the bottom of the flow box at a position lower than the feed pipe 7 attached to the flow box 13. 3. Then, the agglomerated flocs overflowing from the flow box 13 are transferred onto the paper making wire 16 via a smooth surface flow plate 15 with an inclination angle of 5 to 45 degrees from the overflow part to the paper making wire 16. 1. A method for producing paper with a high content of inorganic powder, which comprises supplying and paper-making the paper.