JP2002331509A - Method for heat pressing of woody laminated mat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for heat pressing a woody laminated mat capable of heating uniformly and at a high speed to an inside when a wood piece mat is thermally press molded by steam injection. SOLUTION: A method for heat pressing a woody laminated mat wherein steam is injected to the laminated mat from a central part of a heat pressing machine under a state wherein a steam injecting area is <=80% of total area of the heat pressing machine in a method for heat pressing of the woody laminated mat to be heated and pressurized by injecting high pressure water steam from a group of pores bored on the heat pressing machine by arranging the laminated mat wherein thermosetting adhesives-applied wood piece are laminated, between a pair of heat pressing machines.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for hot pressing a wooden laminated mat.

[0002]

2. Description of the Related Art Conventionally, a wood-based composite material obtained by laminating wood chips coated with a thermosetting adhesive, heating and applying pressure, and laminating and hardening the wood chips has been used as a structural material. As the structural material, board materials such as particle board, fiber board, OSB (oriented strand board), PSL (parallel strand lumber), and OSL (oriented strand board) are used.
Strands and lumbers), and in recent years, these composite materials have been required to have a large cross-sectional shape due to the decrease in large-diameter trees and the enlargement of buildings.

[0003] As means for producing the above-mentioned large cross-sectional shape, a steam injection press capable of heating the inside at a high speed has attracted attention. Steam injection is a method in which steam is injected from holes or slits provided on the surface of a hot plate, and the inside is heated at a high speed by flowing steam into the gaps between the pieces of wood constituting the mat. It is effective as a means for improving productivity to a large cross-sectional shape that takes more time, and these studies have been actively conducted.

A piece of wood used in the above-mentioned woody composite material is
In general, a material that is long in the fiber direction and has a small thickness is used, and a mat made of wood pieces has a structure in which a number of wood piece layers 2 formed by arranging wood pieces 1 are stacked as shown in FIG. Therefore, the size of the pieces of wood varies, and the positions of the pieces are random. Therefore, even if there are many gaps in one layer, by stacking many layers, as shown in FIG. Since different layers of wood pieces are placed above and below the gap,
Holes that can penetrate straight up and down the mat 3 are not usually formed.

FIG. 3 shows a cross section of the mat cut in the thickness direction. In a steam injection press, usually a mat 3
Is a hot platen 4 having a steam injection port 6 and a metal mesh 5
Are in contact with each other. When the steam is injected from the steam injection port 6 to the mat 3, the steam flows through the steam channel 8 formed by connecting the gaps of each layer in a zigzag manner while pushing out the air as shown in FIG. Steam permeates in the direction. Since the steam flow path sometimes runs backward in the thickness direction, in order for the steam to penetrate in the thickness direction, it is necessary to pass through a distance several times to several tens times the linear distance, and the resistance to the flow is It will be very large.

On the other hand, as shown in FIG. 5, the flow of steam in the plane direction of the mat linearly passes through the gap between the wood pieces and reaches the outside of the mat from the steam injection port at a substantially shortest distance. Low resistance to flow. Therefore, the steam easily flows in the plane direction even though the thickness direction is short at the straight line distance.

In addition, since steam is more likely to escape outside the mat than at the center of the mat, the amount of steam injected from the outside of the hot plate is relatively larger than that at the center, and is injected from the center. The amount of steam produced is reduced. Therefore, as shown in FIG. 6, there is a problem that air remaining without being displaced stays and air pockets are formed, and the central portion of the mat tends to be insufficiently heated. Regarding this solution, for example,
As described in Japanese Patent Application Publication No. 00-280207, a method has been proposed in which steam is injected from one hot plate and vacuum is drawn from the other hot plate.

However, compared to the method of injecting steam from both sides, the method of injecting steam from one side doubles the distance that steam must pass, so that the resistance is also doubled. Such that the resistance in the thickness direction is smaller than that in the layer direction,
It is effective for heating a mat of about 20 mm or less, but when manufacturing a wood-based composite material for a structural material having a thickness of 40 mm or more, there is a great possibility that it takes much time to heat the entire mat. Further, the injection vapor pressure is 0.4 MPa or more, and since a differential pressure higher than the atmospheric pressure (0.1 MPa) cannot be obtained by evacuation, the influence on the vapor permeation rate is small. In addition, there is a difference in steam pressure on both sides of the hotplate. Since there is a correlation between the steam pressure and the steam temperature, a difference in pressure causes a difference in temperature and a thermal distortion occurs in the molded product, which causes a problem that the molded product may be warped.

[0009]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a uniform and high-speed heat-press molding of a wood chip mat by steam injection in view of the above-mentioned problems in producing the conventional wood-based composite material molded article. Another object of the present invention is to provide a method for press-pressing a wood-based laminated mat capable of heating the interior of the mat.

[0010]

According to the present invention, a laminated mat formed by laminating wood pieces to which a thermosetting adhesive is applied is arranged between a pair of heating press boards, and is provided on the heating press board. In the heating press method for a wood-based laminated mat, in which high-pressure steam is injected from the group of pores onto the laminated mat to heat and pressurize, the steam injection area from the center of the heated press panel to the laminated mat is 80 of the total area
% Of the wood-based laminated mat.

[0011] The raw materials of the above wood chips include cedar, cypress,
Conifers such as spruce, fir, and radiata pine; broadleaf trees such as birch, apiton, chamelere, sengonglaut, and aspen, etc. Plant material.
Examples of the form of the woody material include raw materials such as logs and thinned wood of the above species, scrap materials generated at factories and housing construction sites, waste pallet materials discarded after transporting members, demolition waste materials generated when dismantling buildings, and the like. Can be

[0012] As an apparatus for processing the above raw materials into wood chips,
Examples include a chipper, a crusher, a defibrator, a ring flaker, a rotary cutter, a rotary flaker, and the like.

The types of wood pieces obtained from the above processing apparatus include chips (several cm to several tens cm pieces) from a chipper or a crusher, fibers from a defibrillator, and particles (several mm to From a rotary cutter, a stick (a piece of chopstick-shaped wood with a cross section of several mm and a length of several tens of cm), a strand from a rotary flaker (a piece of wood with a thickness of about 1 mm and a length of several tens of cm), etc. Is mentioned.

The thermosetting adhesive is a phenol resin,
Adhesives for the wood industry used for plywood and particle boards, such as urea resins and isocyanates. These adhesives are used alone or in combination of several types. The mixing amount of the adhesive depends on the density, shape and surface condition of the wood piece, but is usually used at a ratio of 1 to 20% by weight based on the weight of the wood piece.

A thermosetting adhesive can be adhered to the surface of the wood piece by using an application means such as a spray on a conveyor or in a drum blender.

As the laminating apparatus for forming the above-mentioned wooden laminated mat (hereinafter referred to as mat), a laminating apparatus suitable for the shape of a piece of wood is used. For example, a fibrous material such as a fiber is a dry carding machine or a wet type. For a small piece such as a particle, a weight-regulating type forming machine or a volume-regulating type forming machine; a disc-orienter, a cross-orienter, or the like for a strand or the like having a particularly long shape in the fiber direction is used.

The heating press used in the present invention is provided with a large number of holes and slits (groups of holes) for injecting steam into the mat. There is no particular limitation on the diameter of the hole or the gap size of the slit, but generally, the range of 0.5 to 5.0 mm is preferable.

According to the present invention, steam is injected from the center of the heating press board to the above mat at a steam injection area of 80% or less of the entire area of the heating press board. That is, the position where the above-mentioned group of pores is arranged is a region including the center of the heating press plate, and the area ratio of the region to the entire heating press plate is 80%
%, The effect of the present invention appears. When the steam is selectively injected from the specific position, the steam flowing out from the end face is suppressed as shown in FIG. Therefore, insufficient heating at the center of the mat can be suppressed. More preferably, it is 60% or less.

Further, in the method of the present invention, before the high-pressure steam is injected, it is preferable that the space in which the mat is arranged is placed in a reduced pressure state, since air that hinders the penetration of the steam is removed. This is preferable in that it can increase the penetration rate of the polymer. As a structure of a heating press device that enables the space in which the mat is arranged to be in a reduced pressure state, a structure in which the inside is sealed by an upper mold 10 and a lower mold 11 as shown in FIG. Heating press board 4
In the closed container 17.

The wood-based molded product obtained by the method of the present invention includes particle board, fiber board, OSB
(Oriented Strand Board), PSL (Parallel Strand Lumber), OS
L (Oriented Strand Lumber) and the like.

(Operation) According to the present invention, since steam can be effectively infiltrated into the central portion, the central portion of the mat can be efficiently heated, and insufficient heating can be suppressed. As a result, the molding cycle can be shortened and the occurrence of product defects can be suppressed.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below based on embodiments. (Example 1) Internal width is 1000 mm and length is 3000
In a rectangular area of 800 mm in the width direction including the center point and 1500 mm in the length direction including the center point on the lower surface of the upper die 10 and the upper surface of the lower die 11 having the structure shown in FIG. Arranged at pitch. This steam injection area was 40% of the entire area of the heating press board. afterwards,
The temperature was raised to 180 ° C. Next, chamelere (Eucally
ptus degrupta, density 0.4 g / cm ³ )
(10mm × 4mm)
mm × 400 mm) and a urethane-based adhesive (polymeric MDI; manufactured by Sumitomo Chemical Bayer Urethane Co., Ltd., trade name “Sumijur 4
4V20 ") was spray-coated at 5 parts by weight to obtain 200 kg of a mixture of wood chips and an adhesive.

The thus obtained admixture is laminated while being oriented in one direction, and is laminated to a width of 1,000 mm and a length of 300 mm.
A mat having a thickness of 0 mm and a thickness of 400 mm was prepared, a wire thermocouple was inserted into the center, and the mat was set on the heating press. The upper die 10 of the heating press was lowered until the mat thickness became 160 mm, temporarily stopped, and steam was injected. The steam pressure at this time was 0.05 MPa in relative pressure.

Five seconds after the start of steam injection, the temperature at the center becomes 1
Since the temperature reached 00 ° C., the upper mold 10 was lowered until the thickness became 110 mm. The compression of the mat increased the resistance to the flow of steam, causing the vapor pressure to rise to 0.40 MPa relative pressure. Thirty seconds after the thickness was reduced to 110 mm, the temperature at the center reached an equilibrium state at around 150 ° C., and after maintaining that state for another 30 seconds, the steam injection was stopped. After the steam injection was stopped, the internal steam was leaking, and the internal temperature gradually decreased. Five minutes later, the internal temperature reached 105 ° C, so it was determined that steam had almost escaped.
Raise the upper mold 10 and make the width 1000mm and length 3000
A wood-based molded product having a thickness of 110 mm, a thickness of 110 mm, and a density of 0.6 g / cm ³ was taken out.

After leaving the obtained wood-based molded body indoors for one day, a sample having a width of 40 mm, a thickness of 40 mm and a length of 800 mm was cut out from the vicinity of the center and subjected to a bending test at a span of 640 mm. The flexural modulus of the obtained sample is 1
It was 2 GPa.

(Embodiment 2) Before placing the mat inside the press and lowering the upper die 10 of the press, the space surrounded by the upper die 10 and the lower die 11 by the water ring vacuum pump is set to the atmospheric pressure. The procedure was performed in the same manner as in Example 1 except that the pressure was reduced to -650 mmHg. The temperature at the center from the start of steam injection is 10
The time required to reach 0 ° C. was 3 seconds, and the thickness was 1
After compressing to 10mm, the center temperature is 150 ℃
The time to reach an equilibrium state in the vicinity was 15 seconds.
The flexural modulus of the obtained sample was 12 GPa.

(Comparative Example) The same operation as in Example 1 was carried out except that the steam injection ports were arranged on the entire lower surface of the upper die 10 and the upper surface of the lower die 11 of the press machine. The time required from the start of steam injection until the temperature at the center reaches 100 ° C. is 20 seconds, and even after 5 minutes or more after compressing to a thickness of 110 mm, the temperature at the center does not reach 150 ° C. A molded sample having the same level of physical properties as the examples was not obtained.

[0028]

According to the heating press method of the present invention, a wooden molded product obtained by ordinary hot plate molding can be molded in a short time with high productivity.

[0029]

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the arrangement of wood chips on a single wood chip stacking surface in a mat.

FIG. 2 is a schematic view showing an arrangement of a plurality of laminated wood pieces in a mat.

FIG. 3 is a cross-sectional view in the thickness direction of the wooden laminated mat.

FIG. 4 is a schematic view showing a flow of steam in a thickness direction of the wooden laminated mat.

FIG. 5 is a schematic view showing a flow of steam in a layer direction of a wooden laminated mat.

FIG. 6 is a schematic view showing the flow of steam in the entire wood-based laminated mat by the conventional steam injection method.

FIG. 7 is a schematic diagram showing the flow of steam over the entire mat in the steam injection method according to the first embodiment.

FIG. 8 shows an example of an apparatus configuration for realizing the invention described in claim 2.

FIG. 9 shows another example of a device configuration for realizing the invention described in claim 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wood piece 2 Wood piece layer 3 Woody laminated mat 4 Heating press board 5 Wire mesh 6 Steam injection hole 7 Steam flow direction 8 Steam flow path 9 Air pocket 10 Upper mold of heating press machine 11 Lower mold of heating press machine 12 Hydraulic cylinder 13 Steam piping 14 Boiler 15 Vacuum piping 16 Vacuum pump 17 Sealed vessel

Claims (2)

[Claims] 1. A laminated mat formed by laminating wood pieces to which a thermosetting adhesive has been applied is disposed between a pair of heating press boards, and high-pressure steam is passed through a group of pores formed in the heating press board. Is applied to the laminated mat by heating and pressurizing the wood-based laminated mat, wherein the steam injection area from the center of the heated press board is 80% or less of the entire area of the heated press board. A method of heating and pressing a wood-based laminated mat, which comprises spraying. 2. A space in which said laminated mat is disposed is placed in a reduced pressure state before said high-pressure steam is injected.
A heating press method for the described wood-based laminated mat.