CN113246256A - Production method of ultrahigh-density large-thickness fiberboard - Google Patents
Production method of ultrahigh-density large-thickness fiberboard Download PDFInfo
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- CN113246256A CN113246256A CN202110574127.4A CN202110574127A CN113246256A CN 113246256 A CN113246256 A CN 113246256A CN 202110574127 A CN202110574127 A CN 202110574127A CN 113246256 A CN113246256 A CN 113246256A
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- glue
- fiberboard
- alkaline solution
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
- B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
- B27N3/04—Manufacture of substantially flat articles, e.g. boards, from particles or fibres from fibres
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
- B27N1/00—Pretreatment of moulding material
- B27N1/02—Mixing the material with binding agent
- B27N1/0209—Methods, e.g. characterised by the composition of the agent
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
- B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
- B27N3/08—Moulding or pressing
- B27N3/10—Moulding of mats
- B27N3/12—Moulding of mats from fibres
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
- B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
- B27N3/08—Moulding or pressing
- B27N3/18—Auxiliary operations, e.g. preheating, humidifying, cutting-off
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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Wood Science & Technology (AREA)
- Forests & Forestry (AREA)
- Dry Formation Of Fiberboard And The Like (AREA)
Abstract
The invention belongs to the technical field of high-density fiberboard production, and particularly relates to a production method of an ultrahigh-density large-thickness fiberboard, which comprises the following steps: preparing materials, slicing, washing, cooking, hot grinding, sizing, drying, fiber winnowing, paving, prepressing, continuously hot pressing, curing, sanding, cutting and warehousing, wherein the sizing is to apply an adhesive and an acidic curing agent to fibers; spraying alkaline solution on the upper surface and the lower surface of the pre-pressed plate blank by using an alkaline solution spraying device between the pre-pressing and the continuous hot pressing to enable the glue on the surface of the plate blank to be alkaline; compared with the prior art, the large-thickness and ultrahigh-density fiberboard produced by the invention has the advantages of smooth board surface, high surface joint strength, convenience for secondary processing, no edge breakage, high static bending strength and the like; (2) the curing speed of the urea-formaldehyde glue on the surface of the slab in the continuous hot pressing process is reduced and the over-curing is avoided.
Description
Technical Field
The invention belongs to the technical field of high-density fiberboard production, and particularly relates to a production method of an ultrahigh-density large-thickness fiberboard.
Background
The production process of the fiberboard mainly adopts urea-formaldehyde glue as an adhesive. In the production and use process, in order to increase the curing strength of the urea-formaldehyde glue and shorten the curing time, an acidic (ammonium chloride) curing agent is generally heated in the glue mixing process. Free formaldehyde exists in the urea-formaldehyde resin adhesive, a curing agent ammonium chloride is added to react with the free formaldehyde in the urea-formaldehyde resin, the ammonium chloride reacts with water and the ammonium chloride is thermally decomposed to respectively release hydrochloric acid, the three reactions are carried out to rapidly reduce the pH value of the urea-formaldehyde resin adhesive, weak acid curing is realized, the molecular weight is gradually increased, and finally the body-type reticular structure resin is formed.
The production of the fiberboard adopts a continuous hot pressing process: when the plate blank enters the hot press, the upper surface and the lower surface firstly contact the steel belt to receive heat conduction; then the water in the plate blank generates water vapor under the combined action of high temperature and high pressure, the heat is gradually transferred from the surface of the plate blank to the core layer, so that the glue in the plate blank is heated to have good fluidity and is uniformly distributed, and then the glue reaches the curing temperature to generate the joint strength and is cured. The disadvantages of such a production process are: because the heating temperature and the heating time of the plate blank are gradually reduced from the surface layer to the core layer, the curing degree and the strength of the surface layer glue and the core layer glue of the plate blank are different.
Particularly, when a high-thickness and ultrahigh-density fiber board is produced, the problem is more prominent because the hot pressing period is long. When producing a large-thickness, ultra-high density fiberboard, the hot pressing cycle may be extended due to the longer heat conduction time required. The surface of the plate blank is subjected to high temperature and high pressure for a long time, and the glue on the surface of the plate blank can generate over-solidification and strength attenuation phenomena, so that the moisture content of the surface of a finished product plate is reduced, the plate surface is embrittled, and the edge is easy to break during processing and is not easy to process. Due to the excessive aging of the glue, the surface bonding strength and the static bending strength are also greatly reduced, and the product quality is seriously influenced.
Therefore, it is necessary to develop a method for producing ultra-high density and large thickness fiberboard to reduce the curing rate of the surface urea-formaldehyde glue and avoid over-curing during the continuous hot pressing of the board blank.
Disclosure of Invention
The invention provides a production method of an ultrahigh-density large-thickness fiberboard, aiming at the problem of excessive curing of glue on the surface of a slab in the hot pressing process.
In order to achieve the purpose, the invention adopts the technical scheme that: a production method of an ultrahigh-density large-thickness fiberboard comprises the following steps: preparing materials, slicing, washing, cooking, hot grinding, sizing, drying, fiber winnowing, paving, prepressing, continuously hot pressing, curing, sanding, cutting and warehousing, wherein the sizing is to apply an adhesive and an acidic curing agent to fibers; and between the pre-pressing and the continuous hot pressing, spraying alkaline solution on the upper surface and the lower surface of the pre-pressed plate blank by using an alkaline solution spraying device to enable the glue on the surface of the plate blank to be alkaline.
The most commonly used urea-formaldehyde glue for the production of the fiber board is an acid curing glue, and the urea-formaldehyde glue has the most ideal bonding strength for the fiber board under the condition of weak acidity (pH value of 4.5-6). The curing time is prolonged as the pH of the urea-formaldehyde glue is increased. The pH value in the urea-formaldehyde glue determines the reaction mechanism and the reaction rate, and because free aldehyde, reactive sites of urea, hydroxymethyl and the like exist in the urea-formaldehyde glue, the curing time of the urea-formaldehyde glue and the pH value form a certain linear relationship. Alkaline solution is sprinkled through surface about to the slab in this application for slab surface glue is basicity, reduces the solidification rate of slab surface glue in continuous hot pressing process, thereby avoids slab surface glue to overcure.
Preferably, after spraying alkaline solution on the upper surface and the lower surface of the pre-pressed slab, the pH value of the slab surface glue is 8.3-9.0.
Preferably, the pH of the alkaline solution is 9.5 to 11.7.
Preferably, the alkaline solution is a sodium hydroxide solution.
Preferably, the alkali liquor spraying device comprises an upper atomizing water pipe and a lower atomizing water pipe, and the flow ratio of alkali liquor in the upper atomizing water pipe and the lower atomizing water pipe is 1: 4-2: 3.
Preferably, the flow ratio of the alkali liquor in the upper atomization water pipe and the lower atomization water pipe is 1: 2.
Preferably, urea-formaldehyde glue and ammonium chloride curing agent are applied to the fibers in the sizing step.
Preferably, the urea-formaldehyde glue and the ammonium chloride curing agent are sequentially applied to the fibers in the sizing step, or the ammonium chloride curing agent and the urea-formaldehyde glue are mixed before the sizing, and the mixed urea-formaldehyde glue and the ammonium chloride curing agent are applied to the fibers in the sizing step.
Compared with the prior art, the invention has the advantages and positive effects that:
compared with the prior art, (1) between prepressing and continuous hot pressing, alkaline liquor spraying devices are utilized to spray alkaline solution on the upper surface and the lower surface of the prepressed plate blank, so that the glue on the surface of the plate blank is alkaline, the curing rate of the urea-formaldehyde glue on the surface of the plate blank in the continuous hot pressing process is reduced, and over-curing is avoided;
(2) the large-thickness and ultrahigh-density fiberboard produced by the invention has the advantages of smooth board surface, high surface joint strength, convenience for secondary processing, no edge breakage, high static bending strength and the like.
Detailed Description
In order that the above objects, features and advantages of the present invention may be more clearly understood, the present invention is further described below.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and thus the present invention is not limited to the specific embodiments of the present disclosure.
Example 1
As described further below, a method for producing an ultra-high density large thickness fiberboard comprises the steps of: preparing materials, slicing, washing, stewing, hot grinding, gluing, drying, fiber winnowing, paving, prepressing, continuously hot pressing, preserving, sanding, cutting and warehousing.
The ultra-high density large-thickness fiberboard refers to an ultra-high density fiberboard with the thickness not less than 12 mm. The density of the high-density board is 600-900 kg/cubic meter, and the ultra-high density fiberboard refers to a fiberboard with the density higher than that of the high-density board.
Sizing is to apply adhesive and acidic curing agent to the fibers; and (4) spraying alkaline solution on the upper surface and the lower surface of the pre-pressed plate blank by using an alkaline solution spraying device between pre-pressing and continuous hot pressing (after pre-pressing), so that the glue on the surface of the plate blank is alkaline.
After the alkaline solution is sprayed on the upper surface and the lower surface of the pre-pressed plate blank, the PH value of the glue on the surface of the plate blank is 8.3 (the general trend is that the larger the thickness of the finished product fiberboard is, the larger the set PH value of the glue on the surface of the plate blank after the alkaline solution is sprayed is, and the specific set value is that the PH value of the glue on the surface of the plate blank after the alkaline solution is sprayed is determined through tests).
The alkaline solution is sodium hydroxide solution, and the pH value of the alkaline solution is 9.5-11.7.
When the thickness of the produced finished product fiberboard is changed, the PH value of the glue on the surface of the slab needs to be adjusted after the alkaline solution is sprayed, and the adjusting method comprises the following steps: the PH value of the alkaline solution is not changed, but the moving speed of the plate blank when the alkaline solution is sprayed is adjusted; the rate of movement of the mat is constant while spraying the alkaline solution, but the PH of the alkaline solution is changed.
The alkali liquor spraying device comprises an upper atomizing water pipe and a lower atomizing water pipe, and the flow ratio of alkali liquor in the upper atomizing water pipe to the alkali liquor in the lower atomizing water pipe is 1: 4-2: 3. Preferably, the flow ratio of the alkali liquor in the upper atomization water pipe and the lower atomization water pipe is 1:2 (the alkali liquor sprayed on the lower surface of the plate blank partially drips). The technical scheme is adopted to ensure that the PH values of the glue on the upper surface and the lower surface of the plate blank are basically consistent after the alkaline solution is sprayed.
Urea-formaldehyde glue and ammonium chloride curing agent are applied to the fibers in sequence in the sizing step. The urea-formaldehyde glue is an acid curing glue, and the urea-formaldehyde glue has the most ideal bonding strength to the fiberboard under the condition of weak acidity (pH value of 4.5-6). The curing time is prolonged as the pH of the urea-formaldehyde glue is increased.
The pH value in the urea-formaldehyde glue determines the reaction mechanism and the reaction rate, and because free aldehyde, reactive sites of urea, hydroxymethyl and the like exist in the urea-formaldehyde glue, the curing time of the urea-formaldehyde glue and the pH value form a certain linear relationship.
The pH of the urea-formaldehyde glue is about 8.0 before the ammonium chloride curing agent is applied to the fiber; the PH of the glue was about 7.0 after the ammonium chloride curative was applied to the fibers.
Example 2
The difference between this example and example 1 is: after alkaline solution is sprayed on the upper surface and the lower surface of the pre-pressed plate blank, the PH value of glue on the surface of the plate blank is 9.0, the PH value of the glue on the surface of the plate blank cannot be too large, if the PH value of the glue is too large, the plate blank is not completely cured after being continuously hot-pressed, the temperature of the plate is still above 100 ℃, and steam bounce still exists. After the plate leaves the hot press and is separated from the constraint of pressure, the thickness still rebounds, the density of the product becomes low, the structure is damaged, the quality of the plate is greatly influenced, and the density and the service performance of the plate are directly influenced.
The ammonium chloride curing agent and the urea-formaldehyde glue are mixed prior to sizing, and the mixed urea-formaldehyde glue and ammonium chloride curing agent are applied to the fibers in the sizing step.
Example 3
The difference between this example and example 1 is: sizing is the application of a thermosetting phenolic resin adhesive and an acidic curing agent phosphoric acid to the fibers.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in other forms, and any person skilled in the art may apply the above-mentioned technical details to other fields by using the equivalent embodiments with equivalent changes or modifications, but any simple modification and equivalent changes made to the above embodiments according to the technical spirit of the present invention may still fall within the protection scope of the technical solution of the present invention.
Claims (8)
1. A production method of an ultrahigh-density large-thickness fiberboard comprises the following steps: preparing materials, slicing, washing, stewing, hot grinding, gluing, drying, fiber winnowing, paving, prepressing, continuous hot pressing, curing, sanding, cutting and warehousing, and is characterized in that,
the sizing is to apply adhesive and acidic curing agent to the fiber;
and between the pre-pressing and the continuous hot pressing, spraying alkaline solution on the upper surface and the lower surface of the pre-pressed plate blank by using an alkaline solution spraying device to enable the glue on the surface of the plate blank to be alkaline.
2. The method for manufacturing ultra-high density large thickness fiberboard of claim 1, wherein the PH of the surface glue of the slab is 8.3 to 9.0 after spraying the alkaline solution on the upper and lower surfaces of the slab after the pre-pressing.
3. The method for manufacturing an ultra-high density large thickness fiberboard of claim 2, wherein the PH of the alkaline solution is 9.5 to 11.7.
4. The method for producing an ultra-high density large thickness fiberboard of claim 3, wherein the alkaline solution is a sodium hydroxide solution.
5. The method for producing an ultra-high density large thickness fiberboard of claim 1,
the alkali liquor spraying device comprises an upper atomizing water pipe and a lower atomizing water pipe, and the flow ratio of alkali liquor in the upper atomizing water pipe and the lower atomizing water pipe is 1: 4-2: 3.
6. The method for producing ultra-high density large thickness fiberboard of claim 5, wherein the flow ratio of the alkali liquor in the upper atomization water pipe and the lower atomization water pipe is 1: 2.
7. The method for producing an ultra-high density large thickness fiberboard of any one of claims 1 to 6, wherein urea formaldehyde glue and ammonium chloride curing agent are applied to the fibers in the sizing step.
8. The method for producing an ultra-high density large thickness fiberboard of claim 7,
the urea-formaldehyde glue and the ammonium chloride curing agent are sequentially applied to the fibers in the sizing step, or the ammonium chloride curing agent and the urea-formaldehyde glue are mixed before sizing, and the mixed urea-formaldehyde glue and the ammonium chloride curing agent are applied to the fibers in the sizing step.
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| CN202110574127.4A CN113246256B (en) | 2021-05-25 | 2021-05-25 | Production method of ultrahigh-density large-thickness fiberboard |
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| CN202110574127.4A CN113246256B (en) | 2021-05-25 | 2021-05-25 | Production method of ultrahigh-density large-thickness fiberboard |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1306470A (en) * | 1998-06-23 | 2001-08-01 | 玛索尼特公司 | Method for making composite board using phenol formaldehyde binder |
| CN103085147A (en) * | 2011-11-02 | 2013-05-08 | 大亚科技股份有限公司 | Production method of medium- and high-density fiberboard ultralow in formaldehyde emission |
| CN104210009A (en) * | 2013-06-05 | 2014-12-17 | 北京林业大学 | Method for controlling density distribution of cross section of fibreboard |
| CN106003350A (en) * | 2016-07-13 | 2016-10-12 | 大亚人造板集团有限公司 | Preparation method and application of mildew preventive for artificial board |
| CN109129755A (en) * | 2018-11-07 | 2019-01-04 | 广西横县丽冠人造板有限责任公司 | A kind of production method of high moisture-proof medium density fiber desk personality board |
-
2021
- 2021-05-25 CN CN202110574127.4A patent/CN113246256B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1306470A (en) * | 1998-06-23 | 2001-08-01 | 玛索尼特公司 | Method for making composite board using phenol formaldehyde binder |
| CN103085147A (en) * | 2011-11-02 | 2013-05-08 | 大亚科技股份有限公司 | Production method of medium- and high-density fiberboard ultralow in formaldehyde emission |
| CN104210009A (en) * | 2013-06-05 | 2014-12-17 | 北京林业大学 | Method for controlling density distribution of cross section of fibreboard |
| CN106003350A (en) * | 2016-07-13 | 2016-10-12 | 大亚人造板集团有限公司 | Preparation method and application of mildew preventive for artificial board |
| CN109129755A (en) * | 2018-11-07 | 2019-01-04 | 广西横县丽冠人造板有限责任公司 | A kind of production method of high moisture-proof medium density fiber desk personality board |
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| CN113246256B (en) | 2022-11-04 |
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