Compositions: coating or plastic – Coating or plastic compositions – Inorganic settable ingredient containing
Reexamination Certificate
2000-09-06
2002-04-30
Marcantoni, Paul (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Inorganic settable ingredient containing
C264S241000, C264S333000, C264SDIG004
Reexamination Certificate
active
06379457
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a vegetable fibre cement moulded body which utilises vegetable fibre as a reinforcing material and to a method of manufacturing the same.
BACKGROUND ART
Vegetable fibre cement moulded bodies, for example, vegetable fibre cement boards, are normally manufactured by kneading ligneous fibre obtained by processing wood into flakes, excelsior, wood fibre, and the like, or bamboo fibre obtained by processing bamboo in a similar manner, various types of cement, and water, and moulding this kneaded material, followed by curing and hardening of the cement. As sources of ligneous fibre, various kinds of softwood and hardwood timber are widely used. However, recent years have seen a tendency toward timber shortages, and wood conservation is also required from the viewpoint of global environmental protection. As raw materials to replace wood, bamboo materials, which grow rapidly compared to softwood and hardwood timber, and are strong and have a high degree of resiliency, have been gaining attention. However, bamboo materials contain soluble sugars, soluble resins, or the like, which are well known as substances that inhibit the hardening of cement. Therefore, in order to put into practical use materials which contain a large amount of substances that inhibit cement hardening, such as bamboo materials, as raw materials for vegetable fibre materials, an arrangement is necessary for facilitating the smooth hardening of cement.
The following methods have been conventionally proposed as methods of eliminating the cement hardening inhibition caused by the soluble sugars and resins contained in vegetable fibre materials.
For example, a method is cited wherein hardening of cement is promoted by impregnating or mixing in with the vegetable fibre materials metallic salts such as calcium chloride, magnesium chloride, aluminium chloride (Japanese Patent Laid-Open No. 51-26930, Japanese Patent Laid-Open No. 51-151722, Japanese Patent Laid-Open No. 60-118658). Furthermore, Japanese Patent Publication No. 55-14827 discloses a method of rapidly hardening and moulding a ligneous cement moulding wherein a ligneous raw material is made into fine pieces and mixed with water and ultra-rapidly hardening cement to which ferric chloride is added and mixed and then hardened and moulded by heating and pressure-fastening in the range of 90-120° C.
In the above-described method in which a hardening acceleration agent is added, hardening of cement is performed under conditions of pressurisation and heating with the use of, for example, a hot press method, steam curing in a state of fastening, or the like. However, in a system which uses a vegetable fibre material containing a large amount of a substance that inhibits cement hardening, such as a bamboo fibre material, cement does not easily harden at ordinary temperatures, and even if the cement hardens, the strength of the resulting moulded body is extremely low. In addition, for metallic salts used as hardening acceleration agents, chloride types are commonly used; in cases where a chloride-type hardening acceleration agent is used in a construction material, there is a fear that metallic parts such as screws for fastening will rust at the time of constructing the resulting moulded body, and that metallic parts of kneading machines, iron plates for moulding, and the like, will rust at the time of producing the moulded body. In a system wherein a vegetable fibre material containing a large amount of a substance that inhibits cement hardening is used, there is also a fear that since hydration of the cement is markedly delayed, these hardening acceleration agents will not work effectively.
Another method is cited wherein resin portions within excelsior are removed in advance by soak-treating it in river water, sea water, and/or a chemical solution, and using the resulting excelsior (Japanese Patent Laid-Open No. 55-164054). Here, it is stated that, in order to remove the resin portions within the excelsior raw material to an extent which does not adversely affect the production of the excelsior cement boards, it is necessary to pre-soak the excelsior in water for 2 to 10 hours, depending on the type of resin, using mainly cold water in the range of 1 to 45° C. In this case, since a long period of time is required for the soaking treatment, it cannot be denied that there is a reduction in productivity. Moreover, in order to obtain stable product quality, a long period of time is required for soaking, and there is an apprehension that the product quality will vary depending on the type of wood used. Furthermore, Japanese Patent Publication No. 61-4784 discloses a method of manufacturing a ligneous cement board characterised in that the ligneous material is treated beforehand with a salt having 1 or more sulphate radicals selected from the group consisting of magnesium sulphate, calcium sulphate, aluminium sulphate and zinc sulphate, calcium hydroxide and/or calcium carbonate, and 1 or more carboxylic acids selected from the group consisting of formic acid, acetic acid, and oxalic acid, and cement is then mixed in. Moreover, Japanese Patent Publication No. 61-5422 discloses a method of manufacturing a ligneous cement board characterised in that a treatment for preventing the inhibition of the cement hardening of a ligneous material is performed with an aluminium salt of a strong acid and an acetate, and the ligneous material which has undergone this cement hardening inhibition treatment is used to manufacture the ligneous cement board. These treatments all bring about an increase in the cost of the draining process for soaking treatment solutions and in running costs.
There is also a method wherein a substance that inhibits cement hardening in a ligneous material is made insoluble by treatment with paraformaldehyde or formalin (Japanese Patent Laid-Open No. 50-127925). However, the pharmaceuticals used in this method are dangerous, and expenses are incurred for chemical waste treatment facilities, work site, environment facilities and the like, which leads to an increase in costs.
Furthermore, Japanese Patent Publication No. 5-65455 discloses a method of manufacturing a ligneous cement board by kneading a ligneous material, cement and water to form a mixed mat, then moulding the mixed mat by pressure-fastening, and curing and hardening, wherein a metallic compound comprising 1 or more substances selected from sulphates, chlorides, or hydroxides of iron, copper, zinc or lead is mixed into the kneading water, and the metallic compound is bonded to a component extracted from the ligneous material to form a highly stable complex, thereby preventing cement hardening inhibition due to the extracted component.
Furthermore, Japanese Patent Laid-Open No. 8-2954 discloses a method of treating a ligneous reinforcing material characterised in that a surface of the ligneous reinforcing material is coated with calcium carbonate by adding to and mixing in the ligneous reinforcing material calcium hydroxide and bicarbonate of an alkali metal and/or ammonia and heating.
The above-mentioned conventional technologies are methods which prevent substances that inhibit hardening from diffusing into cement by causing gelling to start while the amount of the substances which inhibit cement hardening (soluble sugars and resins, and the like) being eluted from a vegetable fibre material which has been mixed in a mixture of raw materials as a reinforcing material is relatively small, or a method which prevents substances that inhibit cement hardening from being eluted into the cement by pretreating the vegetable fibre material for reinforcement with a chemical. However, in cases where bamboo fibre and the like, which contains a large amount of soluble sugars and resins, as compared to such ligneous fibre materials for reinforcement as softwood and hardwood timber, is used as a vegetable fibre material for reinforcement, since there is a possibility that the soluble sugars and resins will be eluted before the cement hardens, there is a fear that the
Harada Hiroshi
Karibe Hajime
Sotokawa Sachiko
Yamamoto Masahiko
A & A Material Corporation
Marcantoni Paul
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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