KR20110062424A - Method for manufacturing particle board - Google Patents

Abstract

PURPOSE: A manufacturing method of an environment-friendly particle board is provided to reduce cost of products while reducing environment problems by using recycled wood chips not wood or ash lumber. CONSTITUTION: A manufacturing method of an environment-friendly particle board includes the following steps: crushing raw materials into chips; drying the crushed chips; sorting the dried chips according to size and weight; coating the chips with an additive and an adhesive; forming a mat by arranging the chips in order; manufacturing a particle board panel by pressing the molded mat; cooling the panel; and wrapping the cooled panel after cutting the panel to a setting size.

Description

Eco-Friendly Particle Board Manufacturing Method {METHOD FOR MANUFACTURING PARTICLE BOARD}

The present invention relates to a method for manufacturing an environmentally friendly particle board, and more particularly to a particle board manufacturing method using a combination of non-added formaldehyde (NAF) adhesive and green adhesive (Green Resin) to reduce the amount of formaldehyde dissipation to natural wood materials. It is about.

A conventional particle board is obtained by crushing wood, applying an adhesive to a wood body obtained by cutting and then compression molding. Particle boards are widely used in interior and exterior wall finishing materials, partition materials, decorative materials, and kitchen furniture because of their low manufacturing cost, easy construction, and low strength.

However, in general, urea-formaldehyde resin or urea-melamine-formaldehyde resin adhesive used in the manufacture of particle boards releases formaldehyde and volatile organic compounds, which are harmful to human health. Therefore, a method of using MDI (4,4'-diphenylmethane diisocyanate), which is an isocyanate-based urethane adhesive, is generally used as an eco-friendly NAF (Non Added Formaldehyde) resin that does not use formaldehyde.

MDI (4,4'-diphenylmethane diisocyanate) has the advantage of excellent water resistance of the board manufactured after adhesiveness and hardening, but it is very sensitive to moisture and requires a special input device in addition to the existing equipment, and it is not easy to apply on site. The price is also very expensive.

In addition, there is a disadvantage that an expensive release agent must be used to prevent sticking to the hot plate during the press process during the particle board manufacturing process, and because it is sensitive to moisture, there is a limitation that must be handled very sensitively in process conditions. .

Moreover, MDI adhesive is an eco-friendly NAF (Non-added Formaldehyde) adhesive that does not use any formaldehyde component, but in the particle board manufactured using this, small amount of natural formaldehyde naturally occurring in wood materials is detected. .

Other eco-friendly adhesives include natural adhesives such as starch, tannin, and protein extraction adhesives, but they are more expensive than conventional urea resin adhesives or have longer curing times. There are disadvantages.

Therefore, MDI (4,4'-diphenylmethane diisocyanate), an isocyanate-based urethane adhesive showing excellent physical properties as an eco-friendly adhesive, is used only as a middle layer adhesive without a release agent, and is extracted from wood as a surface resin. Particle boards can be manufactured using a composite adhesive using tannin, an environmentally friendly material.

Generally, water and hexamine (Hexamethylenetetramine) may be used as MDI and tannin hardener. However, instead of MDI and tannin, which are generally used for more improved production conditions, DCM with Scavenger function is used for MDI in the middle layer, and tannin (which has a relatively long curing time as a tanner) tannin) In order to shorten the curing time of the adhesive, TA (Tining Agent for Tannin Resin), an amine-based complex curing agent, is used.

Meanwhile, wax is generally added to increase the water resistance of the particle board. The wax is effective for dimensional stabilization such as water absorption and thickness expansion rate of the manufactured particle board.

The present invention was developed to solve the disadvantages of using an MDI adhesive or a tannin adhesive alone as an adhesive of an eco-friendly particle board, while using an MDI adhesive and a tannin adhesive together to take advantage of each adhesive and dissipate the amount of formaldehyde. It is to provide a particle board manufacturing method that reduces the natural wood (native wood) class.

The present invention,

Crushing the raw material into chips;

Drying the shredded chips;

Sorting the surface and middle chips by size and weight of the dried chips;

Applying an adhesive and an additive to the chip using a surface layer and a middle layer applicator;

Arranging the chips in surface-layer-surface order to form a mat;

Thermoforming the molded mat with a press to produce a particle board panel;

Cooling the manufactured panel;

Cutting and cooling the cooled panel to a predetermined size;

It is achieved by changing the type of adhesive and additives applied to the surface and middle layer applicators during the above steps.

The present invention,

When the adhesive is applied to the surface layer and the middle layer in the manufacture of the particle board by using an applicator, a natural adhesive such as MDI adhesive or tannin, which can be used as urea resin or urea-melamine resin or eco-friendly adhesive, is used. When used as an additive, the amount of formaldehyde that is more harmful to human health is greatly reduced to a very small level generated from natural wood.

In addition, by using recycled wood instead of wood or lumber, which is generally used wood raw material, it has the effect of reducing environmental problems and reducing the cost of the product.

Particle board manufacturing method of the present invention

Crushing the raw material into chips;

Drying the shredded chips;

Sorting the surface and middle chips by size and weight of the dried chips;

Applying resin and additives to the chip using a surface layer and a middle layer applicator;

Arranging the chips in surface-layer-surface order to form a mat;

Thermoforming the molded mat with a press to produce a particle board panel;

Cooling the panel;

Packaging by cutting the cooled panel to the set size

It is characterized by consisting of.

The particle board manufacturing method of this invention is manufactured by the following process.

Raw Material Preparing Process:

Recycled wood, which is an input raw material, is manufactured into shaving chips by selectively removing and crushing iron materials or foreign substances.

Recycling waste wood is composed of industrial waste wood or general waste wood. Industrial waste wood is mainly waste wood from construction sites, and general waste wood is mainly composed of waste wood from household goods such as furniture.

Drying Process:

The cut chips thus prepared may be subjected to acid-base chemistry in order to meet a constant acidity condition, and are transferred to a dryer and dried.

Chip Screening Process:

The dried chip chips are transferred to a sorter and sorted into surface chips and middle chips according to the size and weight of the chips.

In general, the surface chip is divided into 200㎛ ~ 2.0㎜, the middle layer is divided into 2.0㎜ or more.

Glue Dosing Process:

After that, the selected surface layer chip and middle layer chip are transferred to the applicator, and resin and additives are applied by using a blender in each applicator. The middle layer chip uses MDI resin, a curing agent, a scavenger, and a wax. DCM is used as a curing agent with Scavenger).

In addition, the surface chip uses tannin resin, tannin curing agent TA, and wax.

The application amount of the resin and the additive is shown in Table 1 below.

Resin (Compared to Chip)

Wax (Comparison of Chips)
TA
DCM vs Chip
Surface layer (tannin)
13-15 wt%

1-2 wt%
5-10% by weight -
MDI
3-5 wt%

0.5 to 1 wt%
-
5-10% by weight

TA is a special hardening accelerator for tannin resins. If it is less than the given content, the productivity may be decreased due to uncuring or the property may be degraded. If the content is exceeded, it may cause the physical properties of the board to fall due to premature or overcuring of the surface layer. This can be

In addition, when the amount of DCM used as an adhesive for MDI, which is an environmentally friendly NAF resin, is low, the degree of curing decreases, and when the amount is excessive, the water content increases, which may cause thermal pressure failure.

Mat Forming Process:

As described above, the surface layer chip and the middle layer chip coated with the MDI resin, the tannin resin, and the additive in the applicator form the mat by arranging the chips in the order of surface layer-layer layer-surface layer.

The composition of the surface layer is 40% to 45% by weight, the middle layer is composed of 55% to 60% by weight. The mat maintains the total moisture content at the same level as the existing particleboard, but the surface moisture content is relatively high. Higher heat transfer to the middle layer during press hot press, and spring back phenomenon is reduced due to the low water content of the middle layer.

Pressing Process:

Thereafter, the formed mat is hot pressed at a hot plate temperature of 200 to 250 ° C., thereby completing a particle board panel. The surface moisture content at the press hot press is relatively higher than the middle layer moisture content so that heat transfer to the middle layer is faster, and the spring back phenomenon is reduced due to the lower moisture content of the middle layer.

After completion, the air-cooled particle board panels are cut and packed to a certain size.

Non-treated
After press
Remarks

Emission
(Perforator, mg / 100g)
0.91
1.13
Perforator Method: EN120

Table 2 relates to measurements of trace amounts of formaldehyde emissions naturally released from natural wood.

Table 2 illustrates the trace amounts of formaldehyde dissipation (DIN EN120 Perforator method) naturally released from natural wood. The desiccator method (KS M 1998-4, 2005), which is a KS test method, is a method to measure the amount of formaldehyde dissipated in a certain panel area to measure the native emission of a heterogeneous native chip. In this case, the perforator method, which is a toluene extraction method based on the sample weight, was used.

As a result, a small amount of formaldehyde was detected in the non-hot pressed chip and the hot pressed chip, which showed that a small amount of formaldehyde was dissipated in the board product even when the NAF adhesive without the formaldehyde component in the adhesive and the additive was used. Means that. The amount of radiation emitted from the wood material itself is called natural emission.

1 is a table illustrating the physical properties of the particle board produced by the production method of the present invention and the particle board produced in the laboratory by the conventional manufacturing method.

Here, 'MDI board' is a particle board using only MDI resin (resin) as an adhesive, 'Tannin board' is a particle board using only tannin resin as an adhesive, and 'Zeroboard' uses tannin resin as a surface layer adhesive. By using MDI, the particle board of the present invention which exceeds the conventional formaldehyde minimum dissipation condition (Super E0, 0.3 mg / L or less) and whose formaldehyde dissipation is close to zero is referred to.

In addition, TA is a special hardener for tannin resin, and refers to an amine-based composite aqueous solution.

In addition, 'IB' refers to internal adhesion as an internal bond.

In addition, 'MOR' refers to the flexural strength as a modulus of rupture.

As shown in Figure 1, when comparing the formaldehyde emitted from the particle board of the present invention prepared by using the MDI adhesive and tannin adhesive in combination with the particle board prepared in a conventional manner, 0.35mg for the conventional MDI adhesive / L (KS), 1.87mg / 100g (EN), 6.69mg / 100g (EN) was released for tannin adhesive, 0.05 for zeroboard using tannin adhesive and MDI adhesive of the present invention mg / L (KS) and 0.96 mg / 100 g (EN) were released. It can be seen that the formaldehyde emission amount is significantly lower than the conventional method using only the MDI adhesive or tannin adhesive, and the level is similar to the native emission specified in Table 2.

In addition, it can be seen that formaldehyde dissipation can be lowered to 0.03mg / L (KS) and 0.61mg / 100g (EN) by increasing DCM, which is a middle layer additive. It can be significantly reduced to a lower level than wood emission, and also shows the effect of DCM as a scavenger.

Tannin board showed the lowest IB value, 0.44N / mm2, and MDI board 0.59N / mm2 and Zeroboard 0.61N / mm2 showed the same level within the margin of error. .

The density was not significantly different from 0.720 to 0.700 g / cm 3 in all specimens, considering the intestinal deviation. The density value of the particle board produced by the method of the present invention satisfies the density 500 to 800 kg / m 3 (0.5 to 0.8 g / cm 3) specified in KS F3104 particle board type.

Figure 2 is a table illustrating the quality test results of the particle board tested in the particle board factory manufactured by the manufacturing method of the present invention.

Here, 'Zeroboard' uses the tannin resin as the surface adhesive and MDI as the middle layer adhesive, exceeding the conventional formaldehyde minimum dissipation condition (Super E0, 0.3mg / L or less). Refers to the particle board of the present invention close to).

In addition, 'IB' refers to internal adhesion as an internal bond.

In addition, 'MOR' refers to the flexural strength as a modulus of rupture.

As shown in Figure 2, using the particleboard manufacturing conditions of the present invention, the physical property test results of the product manufactured in the field of the actual particleboard factory, good results in adhesion, bending strength, etc., and obtained a formaldehyde dissipation amount, 0.09mg / L ( Desiccator method) and 0.46 mg / 100 g (perforator method) were measured. This result is not very different from the quality of the test board manufactured in the laboratory. The number of samples required for the test was three, and the press factor was maintained at 5.5 to 7.0 sec / mm.

1 is a table comparing the characteristics of the particle board produced by the method of the present invention and the particle board produced experimentally by the conventional method.

Figure 2 is a table showing the physical property test results of the particle board tested in the particle board factory by the method of the present invention.

Claims (5)

Crushing the raw material into chips; Drying the shredded chips; Sorting the surface and middle chips by size and weight of the dried chips; Applying an adhesive and an additive to the chip using a surface layer and a middle layer applicator; Arranging the chips in surface-layer-surface order to form a mat; Thermoforming the molded mat with a press to produce a particle board panel; Cooling the panel; Packaging by cutting the cooled panel to the set size Particle board manufacturing method characterized in that consisting of. The method according to claim 1, MDI resin and additives are applied to the middle layer chip, tannin resin and additives are applied to the surface layer chip. The method according to claim 1, Particle board manufacturing method characterized in that the tannin resin is applied only to the surface layer, and the curing time is shortened by using TA, which is a curing agent for tannin. The method according to claim 1, Particle board manufacturing method characterized in that the MDI is applied only to the middle layer so that no release agent is used, and DCM is used together with the middle layer to suppress the formaldehyde emission of the particle board product to a level below the native emission of wood. . The method according to claim 1, The mat maintains the total moisture content at the same level as the existing particleboard, but the surface moisture content is relatively higher than the middle layer, so that heat transfer to the middle layer is accelerated during press hot press, and the spring back phenomenon is reduced due to the low moisture content of the middle layer. Particle board manufacturing method, characterized in that reduced.

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