Patent Application
20180015637
This invention relates to a method of manufacturing medium or high density fiber board, especially to a method of manufacturing high density fiber board using crop straws.
In the current market, there is only technique of manufacturing wood fiber board. Such technique is not applicable when using straws as the raw materials. However, some board manufacturing processes using straws as the raw materials either add cement into the applied liquid to create cement board, or choose specific cotton straws or maize straws. In the first case, although straws are used as the raw materials, the cement board is heavy and rough and is not as good as medium or high density fiber board. In the second case, the applicable field is quite narrow and the productivity is very low. Consequently, the technology to manufacture medium or high density fiber board purely using straws as the raw materials is still blank.
This invention relates to a method of manufacturing crop straw fiber board, wherein the method includes the following steps:
In said step (2) of softening the straw raw materials, horizontal digester is adopted. The digester is inclined to the ground with an included angel of 3 to 6°. The digester is injected with water to digest the raw materials, wherein the weight ratio of water to the straws is 1 to 1. The temperature of the steam in the digester is 80 to 160° C. The pressure in the digester is 3 to 6 kilograms/cm2. The time that the raw materials use to pass through the digester is 10 to 20 minutes.
In said step (4) of sending the straw fibers into the liquid applying system, the straw fibers are pushed in the tube by steam force, while adhesive is sprayed. The weight ratio of the adhesive to the straw fibers is 12 to 100. The straw fibers obtained from drying with hot wind have moisture content of 12% to 18%.
In said step (6) of dehydrating by hot-pressing, the hot-pressing is conducted in a high temperature and medium pressure environment, wherein the temperature is 130 to 200° C., and the pressure is 110 to 150 kilograms/cm2. The said dehydrating by hot-pressing lasts for 40 to 70 seconds. The plate blank obtained has moisture content of 6% to 7%.
In said step (7) of adhering by hot-pressing, the hot-pressing is conducted in a medium temperature and high pressure environment, wherein the temperature is 100 to 150° C., and the pressure is 200 to 260 kilograms/cm2. The process of adhering by hot-pressing lasts for 40 to 70 seconds.
In said step (8) of shaping by cold-pressing, the process of shaping by cold-pressing is conducted in an environment wherein the temperature is −10 to 10° C. and the pressure is 200 to 260 kilograms/cm2. The process of shaping by cold-pressing lasts for 40 to 70 seconds.
The said adhesive is formaldehyde-free artificial board adhesive.
The merits of this invention are: Any crop straws could be selected as the raw materials; it has a wide scope of application; the pollution caused by burning the straws is reduced, resource re-cycling is achieved. Besides, this invention adopts formaldehyde-free adhesive, making the fiber board obtained safe and environmental.
This invention discloses the manufacture of high-density fiber board made of crop straws with the following steps:
In said step (2) of softening the straw raw materials, horizontal digester 5 is adopted. The digester 5 is inclined to the ground with an included angel of 3 to 6°. The digester 5 is injected with water to digest the raw materials, wherein the weight ratio of water to the straws is 1 to 1. The temperature of the steam in the digester 5 is 80 to 160° C. The pressure in the digester 5 is 3 to 6 kilograms/cm2. The time that the raw materials pass through the digester 5 is 10 to 20 minutes.
In said step (4) of sending the straws into the liquid applying system, the straw fibers are pushed in the tube by steam force, while adhesive is sprayed. The weight ratio of the adhesive to the straw fibers is 12 to 100. The straw fibers obtained from drying with hot wind have moisture content of 12% to 18%.
In said step (6) of dehydrating by hot-pressing, the hot-pressing is conducted in a high temperature and medium pressure environment, wherein the temperature is 130 to 200° C., and the pressure is 110 to 150 kilograms/cm2. The said dehydrating by hot-pressing lasts for 40 to 70 seconds. The plate blank obtained has moisture content of 6% to 7%.
In said step (7) of adhering by hot-pressing, the hot-pressing is conducted in a medium temperature and high pressure environment, wherein the temperature is 100 to 150° C., and the pressure is 200 to 260 kilograms/cm2. The process of adhering by hot-pressing lasts for 40 to 70 seconds.
In said step (8) of shaping by cold-pressing, the process of shaping by cold-pressing is conducted in an environment wherein the temperature is −10 to 10° C. and the pressure is 200 to 260 kilograms/cm2. The process of shaping by cold-pressing lasts for 40 to 70 seconds.
The said adhesive is formaldehyde-free artificial board adhesive.
The application of the manufacturing method of the fiber board made of crop straws of this invention is explained in reference of the drawings below.
As shown in
Straw fibers separated in the defiberator 7 are conveyed forward spirally via the transmission tube by steam force pushing device, while adhesive is sprayed from the walls of the tube. The process of stirring and mixing the adhesive is finished while conveying the straw fibers.
The adhesive selected in this invention is formaldehyde-free artificial board adhesive (CN200910200643.X). This adhesive is made of mixture of two formula liquid, i.e. made of mixture of paraffin emulsion and polyvinyl alcohol mixture, wherein the formula of paraffin emulsion is (percentage by weight):
The mixed straw fibers are sent to hot wind with temperature of 100 to 135° C. to dry. This process lasts for 8 to 12 seconds. The dried straw fibers' moisture content is 12% to 18%.
Then the straw fibers are paved to such a density that is needed to make fiber board, and is pre-pressed into a plate blank with thickness of 30 to 180 mm.
As is shown in
The plate blank is sent from No. 1 hot press into No. 2 hot press 9 to be adhered by hot-pressing in a medium temperature and high pressure environment, wherein the temperature is 100 to 150° C., and the pressure is 200 to 260 kilograms/cm2. The process of adhering by hot-pressing lasts for 40 to 70 seconds. The optimal temperature to adhere is 120° C. When the plate blank is dehydrated in No. 1 hot press 8, the adhesive is able to completely adhere and fix the straw fibers under the temperature and press environment in No. 2 hot press 9.
Then the plate blank is sent from No. 2 hot press 9 into No. 3 cold press 10. No. 3 press is cold press, wherein the temperature is −10 to 10° C. to shape the plate blank by cold-pressing. While shaping the plate blank, physical character generated from quick cooling is used to further improve the adhesiveness of the plate blank. The said cold press 10 is formed by adding refrigerant into the pipeline of the hot press board of the existed hot press.
After the three presses are set in tandem, each press has the same pressing time, which means production line is formed and productivity is improved. The plate blank is produced into medium or high density fiber board by trimming and sanding, so as to achieve the industrial standard of the medium or high density fiber board ruled by the Chinese government.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201410774745.3 | Dec 2014 | CN | national |
This application is a national stage entry of PCT Application No. PCT/CN2015/094237 filed on Nov. 10, 2015, which claims the benefit of Chinese Application No. 201410774745.3 filed on Dec. 16, 2014, each of which is incorporated herein by reference
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2015/094237 | 11/10/2015 | WO | 00 |
