JP6785327B2 - Non-adhesive compression method using high frequency of hardwood - Google Patents

Description

The present invention belongs to the manufacturing field of hardwood processing, and particularly relates to a non-adhesive compression method using high frequency for hardwood.

Hardwood is a good material for making furniture and wood products, hard and dense, gorgeous in color, beautiful with delicate patterns, but these woods are expensive due to their slow growth and dense wood structure. Is. Soft wood has a high growth rate, is composed of many flat cells with a radiation arrangement inside, contains resin and tannin compounds in the cell cavity, is filled with air, is soft and elastic, but Poor physical mechanical performance, for example, low density, low hardness, prone to dry deformation, and prone to corrosion. In order to enhance the above performance of soft wood, it is necessary to perform surface treatment and heat treatment on the wood. In some cases, it is necessary to compress hardwood so that it is compressed into hardwood in order to satisfy the conditions for production processing.

Hardwoods obtained by conventional surface treatment, heat treatment, and compression technology are prone to derubbering and paint loss, and the inside is prone to corrosion, cracking, low hardness, and water absorption to crack. In order to increase the hardness of hardwood, it is necessary to laminate multiple hardwoods with an adhesive to manufacture a composite board, however, the manufactured composite board contains formaldehyde and benzene substances, which is not good for health. Therefore, providing hardwood with high hardness and no adhesive is a problem that must be solved urgently at present.

In response to the above problems, the present invention further provides a non-adhesive compression method using a high frequency of hardwood, and the method includes the following steps.

1) Wood pretreatment: Wood is pretreated and the average moisture content of wood is controlled to 10-20%.

2) Heat compression treatment: The pretreated wood is heated to an average temperature of 100-110 ° C. at a high frequency, kept warm for 5-7 minutes, and compressed at the first compression rate Y.

3) Hardening treatment: The heat-compressed wood is heated to an average temperature of 180-220 ° C. at a high frequency, kept warm for 5-8 minutes, and then hardened.

4) Cooling treatment: The surface of the hardened wood is cooled at a rate of 5-15 ° C./min by water cooling technology, and the average temperature of the wood is cooled to 70-90 ° C.

5) Curing treatment: The cooled wood is left at room temperature and cured for 13-15 days to obtain a non-adhesive compressed hardwood.

If the pretreated wood is not immediately heat-compressed, it is necessary to wrap the pretreated wood with tin paper or plastic to ensure the moisture content of the pretreated wood.

The high-frequency heating used for the heat compression treatment and the hardening treatment in the present invention may be carried out in the same equipment or in different equipment, and the upper and lower surfaces of the wood may be heated by a metal plate in the heating process. it can.

In the process of cooling treatment, it can be appropriately cooled to 30-50 ° C. depending on the size and material of the wood. In actual production, if it is necessary to cool to a low temperature, it can be realized by increasing the length of the conveyor. In addition, it is necessary to place a metal plate with a temperature of 180-220 ° C on the upper and lower surfaces of the wood during cooling, and the area ratio of the metal plate to the wood is 1.4-1.6: 1. Water cooling technology is by cooling a metal plate on wood with water. Since the surface temperature of the metal plate is high, when a large amount of water is poured into the metal plate, the temperature of the metal plate is also lowered by steam, the temperature of the wood is lowered at a constant speed, and the temperature lowering effect can be enhanced.

The metal plate for cooling and the metal plate for high-frequency heating may be the same metal plate or different metal plates.

The average moisture content of wood is the average value of the moisture content measured in different layers on the surface and inside of the wood, and the average temperature of wood is the average value of the temperatures measured in different layers on the surface and inside of the wood.

Further improved, the water flow velocity of the cooling treatment becomes 0.9-1.3 m / s. By limiting the water flow velocity, the vaporization rate can be increased and the temperature lowering effect can be enhanced.

Further improved, in the process of cooling treatment, the surface temperature of the wood became 85-90 ° C, and at the same time , the wind was cooled, and the wind speed was 9.2-9.7 m / s and the wind temperature was 55-60 ° C. is there.

Preferably, the angle between the wind direction and the upper and lower surfaces of the wood is 55-58 °.

The wind sources are located on the upper surface and the lower surface of the wood, respectively, and the wind blows upward at an angle of 55-58 ° with the upper surface of the wood with respect to the upper surface of the wood, and the lower surface of the wood with respect to the lower surface of the wood. The wind blows downward at an angle of 55-58 °.

As the surface temperature of wood decreases, the rate of evaporation of water vapor decreases. Air cooling is required when the surface temperature of the wood drops to 85-90 ° C. to ensure a constant velocity drop of the wood surface. Wind cooling plays a role of drying because the water vapor generated in the water cooling process comes into contact with the surface of the wood. It controls the temperature and direction of the wind, increases the evaporation rate of water vapor, increases the drying efficiency, and prevents springback.

Further improved, in the heat compression treatment process, the pretreated wood is heated while maintaining a preset heating rate v ₁ and a preset temperature difference ΔT ₁ . Here, v ₁ = 5-7 ° C./min, ΔT ₁ = 4-7 ° C., and the high frequency is 8-10.5 MHz.

Further to improve, in the curing process, heating rate v ₂ set in advance to heat compressed wood _is heated while maintaining the temperature difference △ T ₂ set in advance. Here, v ₂ = 20-25 ° C./min, ΔT ₂ = 2-5 ° C., and the high frequency is 2.8-16.5 MHz.

The temperature difference in the present invention is the difference between the maximum temperature and the minimum temperature of all the temperatures measured for the upper and lower surfaces of wood and layers having different thicknesses, and the temperature difference is rationally controlled to have a compression effect (the present invention). The temperature difference in the present invention is the difference between the maximum temperature and the minimum temperature of all the measured temperatures for the upper and lower surfaces of the wood and the layers having different thicknesses). It is also within the scope of the protection of the present invention to rationally control the difference in moisture content of wood to enhance the compression effect.

Further improved, between the heat compression treatment and the hardening treatment, further heating and compression treatment is included, and a specific method is to heat the heat-compressed wood to an average temperature of 150-155 ° C. of the wood at a high frequency. , 5-10 min heat retention, high frequency 15-17 MHz, heating rate 15-20 ° C / min, and cooling with water to an average wood temperature of 100-110 ° C, cooling rate 3-5 ° C / min. It is min, and the second compression is performed.

After the heat compression treatment, the wood is also subjected to a temperature rise compression treatment to recompress the structure that the wood absorbs water, eliminate the water absorption status that can exist in the compressed wood, significantly improve its stability, and absorb water. The purpose is to reduce performance. The second compression rate = 5-10%.

Further improved, the first compressibility Y is obtained by the following equation.

Further improved, the specific method of the curing treatment is as follows.

41) The compressed wood is heated to an average temperature of 135-140 ° C. of the wood at a high frequency, kept warm for 2-5 minutes, and the high frequency is 14.2-16.5 MHz.

42) The wood is heated to an average temperature of 180-220 ° C. at a high frequency and kept warm for 2-3 minutes, and the high frequency is 3.7-4.3 MHz.

43) Stop heating, cool the wood with wind to an average wood temperature of 165-170 ° C, keep it warm for 2-3 minutes, and the wind speed is 6.8-8 m / s.

44) The wood is continuously heated to an average wood temperature of 180-220 ° C. at a high frequency, kept warm for 3-5 minutes, and the high frequency is 2.8-3.5 MHz.

The present invention specifically limits the curing treatment and remarkably enhances the curing effect.

Further improved, the specific method of curing is to place the cooled wood on a horizontal dry surface, apply a pressure of 5.5-7.2 MPa to the upper surface of the wood, cure for 3 days, and then cure. Reduce the pressure by 1.2-1.5 MPa daily until pressure is 0 and continue to cure for 10-12 days .

The curing process should be in a dry and dark place. You may go in the warehouse.

Further improved, in the process of heat compression treatment and temperature rise compression treatment, the intermediate region and the surrounding region of wood are heated at high frequencies, respectively, and the high frequency ratio of the intermediate region to the high frequency ratio of the surrounding region is 1: 0.88-. It is 0.94. In the process of hardening treatment, the intermediate region and the surrounding region of the heat-compressed wood are heated at high frequencies, respectively, and the high frequency ratio of the intermediate region to the high frequency ratio of the surrounding region is 1: 0.93-0.96.

The intermediate region and the surrounding region of the wood may be limited by the size of the wood, and in order to improve the uniformity of the heating and curing temperature, a wood having an area ratio of the intermediate region to the surrounding region of 2: 9 is generally selected. To do.

The non-adhesive compressed hardwood produced by the method of the present invention has a very high average hardness and average density, the density and hardness are uniformly distributed, the area of the internal honeycomb structure is small, and the content of air, resin and tannin compound is high. It is extremely low, has a low water absorption rate inside and outside the hardwood, can withstand boiling and intrusion of water, and has stable properties.

Hereinafter, specific embodiments of the present invention will be described in detail. Of course, the specific embodiments described herein are for the purpose of explaining and interpreting the present invention, and are not intended to limit the present invention.

The high-frequency non-adhesive compression method for hardwood according to Example 1 of the present invention includes the following steps.

1) Wood pretreatment: Wood with a density of ρ = 0.6 is pretreated, and the average moisture content of the wood is controlled to 10%.

2) Heat compression treatment: The pretreated wood is heated while maintaining a preset heating rate v ₁ and a preset temperature difference ΔT ₁ at a high frequency, and heated to an average temperature of 100 ° C. of the wood. It is kept warm for 7 minutes, compressed at a compression rate of 45%, v ₁ = 5 ° C./min, ΔT ₁ = 4 ° C., and the high frequency is 6 MHz.

3) curing: heat compression treated heating rate v ₂ set in advance _wood, heating the temperature difference △ T ₂ set in advance while keeping a high frequency, and heated to an average temperature 180 ° C. of the wood, It is kept warm for 8 minutes and cured, and v ₂ = 20 ° C./min, ΔT ₂ = 2 ° C., and the high frequency is 15.5 MHz.

4) Cooling treatment: The surface of the hardened wood is cooled at a rate of 5 ° C./min by water cooling technology, the average temperature of the wood is cooled to 70 ° C., and the water flow velocity of the cooling treatment is 0.9 m / s. Wind cooling is performed at the same time as the surface temperature of the wood reaches 85 ° C., the wind speed is 9.2 m / s, and the wind temperature is 55 ° C.

5) Curing treatment: The cooled wood is placed on a horizontal dry surface, a pressure of 5.5 MPa is applied to the upper surface of the wood, and after curing for 3 days, the curing pressure is reduced by 1.2 MPa every day until it becomes 0. Obtain a non-adhesive compressed hardwood that will continue to cure for 10 days .

The non-adhesive compression method of hardwood according to Example 2-4 of the present invention using high frequency is different from Example 1 in the change of parameters, and is specifically shown in Table 1.

(Table 1)
Table 1 Parameters of the non-adhesive compression method using high frequency for hardwood according to Example 2-4

Example 5
The high-frequency non-adhesive compression method for hardwood according to Example 5 of the present invention includes the following steps.

1) Wood pretreatment: Wood with a density of ρ = 0.6 is pretreated, and the average moisture content of the wood is controlled to 10%.

2) Heat compression treatment: The intermediate region and the surrounding region of the pretreated wood are heated with a preset heating rate v ₁ and a preset temperature difference ΔT ₁ at a high frequency, and the average temperature of the wood is maintained. Heated to 100 ° C, kept warm for 7 minutes, compressed at a compression rate of 45%, v ₁ = 5 ° C / min, ΔT ₁ = 4 ° C, the high frequency in the intermediate region is 9.8 MHz, and the high frequency in the surrounding region. Is 8.8 MHz.

3) Heat-temperature compression treatment: The intermediate region and the surrounding region of the heat-compressed wood are heated to an average temperature of 150 ° C. of the wood at a high frequency and kept warm for 5 minutes. The high frequency of the intermediate region is 16 MHz, and the ambient region The high frequency is 15 MHz, the heating rate is 15 ° C / min, the average temperature of the wood is cooled to 100 ° C with water, the cooling rate is 3 ° C / min, and the second compression is performed, the second. The compression ratio is 5%.

4) The specific method of curing treatment is as follows.

41) heating the compressed treated heating rate v ₂ of the intermediate region and the surrounding region is set in advance of the _timber, heating the temperature difference △ T ₂ set in advance while keeping a high frequency, the average temperature 135 ° C. Wood The high frequency in the intermediate region is 15.6 MHz, the high frequency in the surrounding region is 14.6 MHz, v ₂ = 20 ° C./min, and ΔT ₂ = 2 ° C.

42) Step 41) in treated the heating rate of the intermediate region and the surrounding region preset wood v _2, reheated temperature difference △ T ₂ set in advance while keeping a high frequency, the average temperature of the wood It is heated to 180 ° C. and kept warm for 2 minutes, the high frequency in the intermediate region is 4 MHz, and the high frequency in the peripheral region is 3.8 MHz.

43) The heating is stopped, the average temperature of the wood is cooled to 165 ° C. with wind, the temperature is kept for 2 minutes, and the wind speed is 6.8 m / s.

44) Step 43) in treated the heating rate of the intermediate region and the surrounding region preset wood v _2, continue to heat the temperature difference △ T ₂ set in advance while keeping a high frequency, the average temperature of the wood It is heated to 180 ° C. and kept warm for 3 minutes, the high frequency in the intermediate region is 3.2 MHz, and the high frequency in the peripheral region is 3 MHz.

5) Cooling treatment: The surface of the hardened wood is cooled at a rate of 5 ° C / min by water cooling technology, the average temperature of the wood is cooled to 70 ° C, the water flow velocity of the cooling treatment is 1 m / s, and the wood The wind is cooled at the same time as the surface temperature reaches 85 ° C., the wind speed is 9.2 m / s, the angle between the wind direction and the upper surface of the wood is 55 °, and the wind temperature is 55 ° C.

6) Curing treatment: The cooled wood is placed on a horizontal dry surface, a pressure of 5.5 MPa is applied to the upper surface of the wood, and after curing for 3 days, the curing pressure is reduced by 1.2 MPa every day until it becomes 0. Obtain a non-adhesive compressed hardwood that will continue to cure for 10 days .

The non-adhesive compression method of hardwood according to Example 6-9 of the present invention by high frequency is different from Example 5 in the change of parameters, and specifically, Table 2.

(Table 2)
Table 2 Parameters of the non-adhesive compression method using high frequency for hardwood according to Example 6-9

In Comparative Example 1-14, the parameters of each step of Example 1 and Example 5 are considered, and the results of consideration are shown in Table 3-4, respectively.

(Table 3)
Table 3 Parameters of non-adhesive compression method using high frequency for hardwood according to Comparative Example 1-7

(Table 4)
Table 4 Parameters of non-adhesive compression method using high frequency for hardwood according to Comparative Example 8-14

The consideration of basic performance is as follows.

(Table 5)
Table 5 Basic performance of non-adhesive compressed hardwood manufactured by each method of the present invention

The consideration of water absorption performance is as follows.

With reference to GB / T 1934.1-2009 “Wood Absorption Measurement Method”, the average water absorption rate (%) and water absorption of the non-adhesive compressed hardwood according to Example 1-9 and Comparative Example 1-14 in 6h. Table 6 shows the results of measuring the rate difference (%) and the water absorption thickness expansion rate (%). The average water absorption rate is the average value of each water absorption rate measured in layers having thicknesses of 2 cm, 4 cm, 5 cm, 6 cm and 8 cm on the upper and lower surfaces of non-adhesive compressed hardwood (measures the water absorption rate of a specific thickness). In this case, it can be measured by processing by a method such as cutting or punching), and the water absorption rate difference is the maximum and minimum values of each measured water absorption rate, and the water absorption thickness expansion rate (%) = (Thickness before immersion-thickness after immersion) / Thickness before immersion.

(Table 6)
Table 6 Measurement results of water absorption of non-adhesive compressed hardwood manufactured by each method of the present invention

As is clear from Tables 5 and 6, the non-adhesive compressed hardwood produced by the method of the present invention has significantly improved average density and average hardness, and also has small density difference, hardness difference and water absorption rate difference. The non-adhesive compressed hardwood produced in the present invention has a uniform hardness and density, high performance both inside and outside, and the resin content, tannin compound content and tannin compound content inside the non-adhesive compressed hardwood. The content of the honeycomb-state structure was significantly reduced, indicating that the stability of the non-adhesive compressed hardwood was further guaranteed.

Claims (5)

A wood pretreatment step that pretreats the wood and controls the average moisture content of the wood to 10-20%.
A heat compression treatment step in which the pretreated wood is heated to an average temperature of 100-110 ° C. at a high frequency, kept warm for 5-7 minutes, and compressed at the first compressibility Y.
1) The heat-compressed wood is heated to an average temperature of 135-140 ° C. of wood at a high frequency, kept warm for 2-5 minutes, and has a high frequency of 14.2-16.5 MHz.
2) The wood is heated to an average temperature of 180-220 ° C at a high frequency and kept warm for 2-3 minutes, and the high frequency is 3.7-4.3 MHz.
3) Stop heating, cool the wood to an average temperature of 165-170 ° C with wind, keep it warm for 2-3 minutes, and the wind speed is 6.8-8 m / s.
4) A hardening treatment step in which the wood is continuously heated to an average temperature of 180-220 ° C. of wood at a high frequency, kept warm for 3-5 minutes, and the high frequency is 2.8-3.5 MHz.
The surface of the hardened wood is cooled by water cooling technology at a rate of 5-15 ° C / min to an average temperature of 70-85 ° C, and the water flow velocity of water cooling technology is 0.9-1.3 m / s. Cooling process step ,
The curing treatment step of placing the cooled wood at room temperature and curing it for 13-15 days to obtain a non-adhesive compressed hardwood, and the specific method of curing, put the cooled wood on a horizontal dry surface. After applying a curing pressure of 5.5-7.2 MPa to the upper surface of the wood and curing for 3 days, the curing pressure is reduced by 1.2-1.5 MPa every day until the curing pressure becomes 0, and the curing is continued for 10-12 days. ,
A high frequency non-adhesive compression method for hardwoods, characterized by containing. In the process of cooling, the surface temperature of the wood becomes 85-90 ° C, and at the same time, the wind is cooled. The wind speed is 9.2-9.7 m / s, the wind temperature is 55-60 ° C, and the wind direction and wood. The non-adhesive compression method using a high frequency of hardwood according to claim 2, wherein the angle between the upper and lower surfaces is 55-58 °. The non-adhesive compression method using a high frequency of a hardwood according to claim 1, wherein the first compression ratio Y is obtained by the following formula.

In the process of heat compression treatment and temperature rise compression treatment, the intermediate region and the surrounding region of wood are heated at high frequencies, respectively, and the high frequency ratio of the intermediate region and the surrounding region is 1: 0.88-0.94. .. In the process of hardening, the intermediate region and the surrounding region of the heat-compressed wood are heated at high frequencies, respectively, and the high frequency ratio of the intermediate region to the high frequency ratio of the surrounding region is 1: 0.93-0.96. The non-adhesive compression method using a high frequency of a hardwood according to claim 1. Between the heat compression treatment and the hardening treatment, a temperature heating compression treatment is further included, and a specific method is to heat the heat-compressed wood to an average temperature of 150-155 ° C. of the wood at a high frequency and keep it warm for 5-10 minutes. The high frequency is 15-17MHz, the heating rate is 15-20 ° C / min, and the wood is cooled to an average temperature of 100-110 ° C with water, and the cooling rate is 3-5 ° C / min. The non-adhesive compression method using a high frequency of hardwood according to claim 1, wherein the second compression is performed.