JPS5937425B2 - wood drying method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for drying wood, and more particularly to a new method for boiling or steam drying wood.

Raw wood usually contains a large amount of water, and if it is used as is, the wood will shrink as it dries after use, causing cracks and warping, resulting in peeling at the bonded areas.

For this purpose, it is required that the wood be dried to a moisture content of less than 15 inches.

The easiest way to dry wood is to simply stack the wood in a well-ventilated condition, called sun drying, but drying to a moisture content of around 15% with this method depends on the type of wood. However, it generally takes several years, and even if the squid is dried using this method, it reaches an equilibrium state at a water content of 15, and it is impossible to dry the squid below this level.

For this purpose, various drying methods have been developed, one of which is to steam the wood or heat it with steam.

Regarding this method, the method of Japanese Patent Publication No. 50-16842 and the method of Japanese Patent Application Laid-open No. 48-85704 have been recently developed.

The method disclosed in Japanese Patent Publication No. 50-16842 involves punching one or more holes in unseasoned wood, steaming it at 100 to 110°C for 30 minutes to 3 hours with or without an acrylic resin emulsion, and then exposing it to air for 3 days. This is a method of leaving it to dry.
Although it is a very good method, it still has the following drawbacks.

In other words, since the temperature inside the steamer is as high as 100-110°C, it is necessary to adjust the temperature, humidity, and pressure accurately.
Not only does this incur a large amount of cost, but the adjustment itself is extremely difficult, and the short heating time of 30 minutes to 3 hours causes drawbacks due to drying stress.

Additionally, there are restrictions on the types of wood that can be used, and it is limited to softwoods and hardwoods that are easy to dry and that have been dried at low temperatures to a maximum of around 20%.

Furthermore, among mechanical properties, it has disadvantages such as poor impact bending strength and the color of the wood tends to be dark brown.

In addition, it also has the disadvantage that surface cracks tend to occur when exposed to direct sunlight during drying in the atmosphere.

Furthermore, the method disclosed in JP-A No. 48-85704 involves blowing live steam directly into the raw wood and then drying it with hot air. However, in this method, heat transfer is slower than in the boiling method, and local overheating occurs. As a result, uniform heating is difficult to achieve, and uneven drying is likely to occur.

The inventor of the present invention has been conducting intensive research in order to overcome the drawbacks of the above-mentioned conventional methods. At this time, it was discovered that wood could be dried with high yield in an extremely short period of time if the water in the sealed container was drained and then dried without actively introducing outside air into the container after boiling.This invention is the invention. I have reached the point where I can complete the Q.

That is, in the present invention, wood is immersed in water or hot water, then boiled in a closed container, the water in the closed container is drained without actively introducing outside air, and then the water is boiled in a closed container using conventional methods. This relates to a method for drying wood, which is characterized by drying the wood.

In the present invention, when boiling wood, the wood is first immersed in water or hot water and then boiled in a closed container.

The water or hot water at this time is preferably water of 95°C or lower, preferably hot water of 80 to 90°C.

There is no hindrance to adding a wood softener, such as soap, to the water or hot water if necessary.

After soaking the wood thoroughly in water or hot water, boil it in a closed container.

The means for boiling is not particularly specified, and any of various means may be effectively applied, and boiling may be performed, or boiling may be performed using steam.

This boiling is carried out to ensure that the inside of the wood is thoroughly impregnated with water, and is usually about 50 to 95°C.

The boiling time varies depending on the type of wood and its moisture content, but the boiling time is generally about 3 to 96 hours, which is sufficient to allow water to penetrate into the wood.

This boiling causes the fibers of the wood to swell and the nignin to soften, making it possible to remove components that inhibit drying, such as oils and fats (resins) in the wood.

When boiling is completed, the water in the sealed container is discharged without actively introducing outside air into the sealed container.

That is, after boiling is completed in the closed container, only the water is discharged without opening the closed container.

Due to this drainage, the wood in the closed container is left in an atmosphere containing a large amount of water vapor.

At this time, the water in the container may be drained gradually, or may be removed all at once.

By draining the airtight container in this way without actively opening it, the boiled wood is exposed to an atmosphere with an extremely high water vapor content in the airtight container.

The time for leaving the wood as it is in the sealed container after draining is usually about 30 minutes to 3 hours, preferably 1 to 2 hours.
It takes about an hour.

When draining water during γ, it is preferable to complete the draining within the above-mentioned time period.

Next, in the present invention, the treated wood is dried.

The drying method at this time may be any conventional method, such as hot air drying, vacuum drying, high frequency heating, etc.

The drying temperature may be 40 to 95°C, and any of the above-mentioned methods may be any conventionally known method.

For example, when applying a hot air drying method, hot air heated to a predetermined temperature may be blown into a closed container.

There are no particular restrictions on the wood to which the method of the present invention can be applied, and a wide variety of woods can be used, but Japanese oak is particularly preferred.

An example of an embodiment of the method of the present invention will be described below with reference to the accompanying drawings.

In the drawing, 1 is a sealed container, 2 is wood to be dried, 3 is water, 4 is a water supply port, 5 is a steam blowing pipe, 6 is an overflow pipe, 7
is a drain port, 8 is a line pump, 9 is a blower, 10 is an air heater, 11 is a steam spray nozzle, 12 is a damper, 13
14 indicates a duct, and 14 indicates a ceiling board.

The wood 2 to be dried is left still in a closed container 1, and water is supplied from a water supply port 4 until the wood 2 to be dried is sufficiently submerged.

Next, steam is blown through the steam blowing pipe 5 to boil it.

Drainage during boiling flows out from the overflow vibro.

When boiling is finished, the water is discharged from the discharge lower.

In the present invention, steaming can also be carried out after boiling.

When this steaming is performed, it is desirable that the water flowing out from the discharge lower be circulated by the line pump 8.

Open the damper a short time after draining has finished. On the other hand, hot air heated by the air heater 10 is circulated inside the closed container 1 by the blower 9.

Further, steam can be sprayed from the steam spray nozzle 11 in order to adjust the humidity of the hot air if necessary.

In the present invention, the boiling waste liquid flowing out from the outflow lower can also be used as the next boiling liquid.

Experimental examples are shown below to clarify the features of the present invention.

<Experimental Method> Black tongue and quince were dried using the apparatus shown in the attached drawings under the conditions shown in Table 1 below.

<Experimental Results> When drainage was conducted in a closed container under the conditions shown in Table 1 above, the moisture content of the final wood was 6.5% (weight) for black tongue and 7.2% (weight) for calici. Met.

And those with no warping or cracks in the wood are Fufu 95-9.
It was 7%.

In addition, in this experiment, when the sealed container was opened after boiling and the water was drained in contact with the atmosphere, the moisture content of the final wood after drying for 10 to 12 days was 6.8 in the case of black tan.
% (weight), 7.6% (weight) in the case of Karishi.However, there are extremely many cases where warping or cracking occurs, and the number of cases where no warping or cracking occurs is 50% of Kurokun. In the case of Carisi, it was 60%.

The present invention will be explained below with reference to Examples.

Example 1 Carisi with a moisture content of 45 cm (16 m/m x 300 m/m x 4
000 m/m) and dried using the apparatus shown in the attached drawings.

The amount of water in the sealed container is 60001, and the initial water temperature is 2.
It is 0°C.

The temperature was raised to 85°C over 6 hours, and the mixture was boiled at the same temperature for 48 hours.

After boiling, let it harden for 30 minutes and store the boiled liquid in a sealed container damper 12.
The material was discharged from the discharge lower without opening the material, and then the damper was opened and hot air of 80.degree. C. was blown at a velocity of 1 m/sec between volumes for 5 days to dry it.

The moisture content of the dried wood obtained was 5.5.

Example 2 Carisi with a water content of 45 (32 m/m x 35077 L/m
It was dried using the apparatus shown in the attached drawings.

The amount of water in the sealed container is 60001, and the initial temperature is 20°.
It is C.

It took 8 hours to raise the temperature to 85°C, and boiled at the same temperature for 72 hours.

Next, the boiling liquid was discharged from the discharge lower after about 60 minutes without opening the damper of the sealed container, and the container was dried by blowing hot air at 80° C. at an air velocity of 14 L/see for 10 days.

The moisture content of the dried wood obtained was 60%, and only 4 pieces of wood were warped or cracked.

Example 3 Black tongue with a moisture content of 35% (7m/mX300m/mX4.
ooOm/m) and was dried using the apparatus shown in the attached drawings.

The amount of water in the sealed container is 62001, and the initial temperature is 35°C.
Met.

It took 4 hours to raise the temperature to 90°C, and boiled at the same temperature for 5 hours.

The boiling liquid was then drained in about 25 minutes without opening the damper of the sealed container.

Then, hot air at 75°C was applied at a wind speed of 2 m/see between the volumes for 24 hours.
It was air-dried for an hour.

The moisture content of the obtained wood was 8%, and there were no cracks or warps.

[Brief explanation of the drawing]

The drawing is an example of an apparatus used in carrying out the method of the present invention. 1 is a closed container, 4 is a water supply port, 5 is a steam blowing pipe, 6 is an overflow pipe, 7 is a discharge port, 8 is a line pump, 9
is a blower, 10 is an air heater, 11 is a steam spray nozzle,
12 is a damper, 13 is a duct, and 14 is a ceiling board.

Claims (1)

[Claims] 1 After immersing the wood in water or hot water, boil it in a closed container, then drain the water in the closed container without actively introducing outside air, and then dry it by the usual method. Characteristic wood drying method.