CN100546783C - Light-colored to white wooden material board - Google Patents

Abstract

The present invention relates to light-colored to white wood substrates produced from bleached wood fibers and/or dyed with white pigment beating.

Description

Light-coloured to white wooden material panels

The present invention relates to by the light-coloured to white wood base board of bleaching wood-fibred production and/or dyeing with the Chinese white making beating.

In the wood-base materials field, the market positive maximum expansion of so-called medium density fibre board (MDF) (MDF plate) and high density fiberboard (HDF plate).Output is in the past decade many three times.

MDF can process as traditional particieboard with the HDF plate.Therefore yet, also be applicable to the manufacturing of form parts and be applied to day by day during furniture makes because of its uniform structure.Therefore, for example be used for the goods of indoor layout and decorative purpose (as layout), and high-quality furniture is made by this plank and should like timber structure as seen only be coated with no colored paint or cover layer for keeping then in trade fair.

Certainly, depend on the type of used timber, these planks have more or less significantly brown, and this only has very little aesthetic values in field of furniture.

By disclosed with pigment making beating dyeing with contain dye coloring agent composition the Natural color of wood-fibred is compensated among the WO-A-04/35276.Can obtain so coloured, fully dyeing, sun-proof and therefore aesthetic high-quality MDF plate, this plate is applicable to that durable goods for example are used for the production of the furniture of sphere of life.

Yet, not light at present or even white wood base board, especially MDF plate.For example the production of kitchen or bathroom goods is meaningful especially yet this plate is especially for furniture and indoor ornament.

Although know is by association with pulp bleaching and interpolation Chinese white or white filler, blue colorant and fluorescent whitening agent production blank sheet of paper already, and at for example Paper Trade Journal, 145, the 26-27 page or leaf has description in (1961), but those skilled in the art not expectation can obtain white wood base board by this way, particularly the MDF plate.

Therefore, thus used wood-fibred still comprises oxidation-sensitive variable color and the material (for example lignin) that no longer comprises in paper pulp in the production of MDF plate.In addition, the MDF plate is produced down at 200 ℃, is higher than the temperature of paper production far away, and therefore, except the natural brown of wood-fibred, the brown that generating process is relevant owing to the thermal decomposition of oxidation and wooden composition is painted.In addition, the MDF plate that adds furniture exposing to the open air basically under light is more permanent and stronger and cause tangible yellowing than conventional paper.

Therefore the purpose of this invention is to provide light color or white wood base board.

Therefore, found the light-coloured to white wood base board produced by the wood-fibred of bleaching.

In addition, found light-coloured to white wood base board with Chinese white making beating dyeing.

And, found that wherein dispersion additionally comprises fluorescent whitening agent with the light-coloured to white wood base board of Chinese white dispersion making beating dyeing.

At last, found by the wood-fibred production of bleaching and the light-coloured to white wood base board that dyes with the Chinese white making beating.

Particularly, found the wood base board of the light-coloured to white that dyes by the wood-fibred production of bleaching and with Chinese white dispersion making beating, wherein dispersion comprises fluorescent whitening agent.

Wood base board according to the present invention is characterised in that their brightness or their whiteness.Depend on the combination of the method that adopts, required whiteness is determined easily.Especially for example obtain blank by the wood-fibred of bleaching with Chinese white dispersion making beating dyeing, wherein dispersion additionally comprises fluorescent whitening agent.Light plate with less whiteness is also only by the bleaching wood-fibred or by just obtaining with Chinese white making beating dyeing.

Can be MDF or HDF plate or particieboard according to wood base board of the present invention.Preferred especially MDF plate.

MDF and HDF plate are usually with continuation method production.The wood chip (fragment) moist in small, broken bits that at first will wash preheats about 80 ℃ and softening in boiling vessel under the temperature of the pressure of 2-5 crust and 100-150 ℃ then.In the refiner in downstream, make this fragment de-fibering then.This refiner has radial clearance angle by two and the metal dish of rotation in the opposite direction close to each other is formed.Fiber leaves refiner by so-called spray tree lace (blowline).Here, use glue usually.Used adhesive is generally urea/formaldehyde resin, strengthens with melamine under some situation, perhaps for moist-proof board urea/melamine/formaldehyde resin.Isocyanates is also as adhesive.This adhesive is applied to fiber with required additive (for example curing agent, paraffin dispersion, colouring agent) usually.The fiber of having used glue is then by drying machine, and being dried to water capacity therein is 8-15 weight %.Under some individual cases, this glue also only is applied to the fiber of drying in the continuous running mixer of special use subsequently.

In the production of particieboard, being applied in the continuous mixer on the formerly dry fragment of glue carried out.

To use the fiber or the fragment of glue then and pour out, obtain plate if be fit to the cold prepressing reality and under 170-240 ℃, in hot press, suppress to obtain piece (mat).

In production, use bleaching wood-fibred (following term " wood-fibred " and " fragment " are as broad as long and term " wood-fibred " also mean comprise " fragment ") according to the embodiment of light wood base board of the present invention.

In the chemical bleaching of wood-fibred, the contained color impurities of timber is eliminated or made it invalid by oxidation and/or reduction chemicals.For example hydrogen peroxide, ozone, oxygen and organic and inorganic persalt such as peracetate, percarbonate and perborate, especially its alkali metal salt, particularly sodium salt is applicable to oxidation bleaching, preferred percarbonate and hydrogen peroxide.For example reduction-sulfurization compound such as dithionite, dithionite, sulphite or sulfur dioxide, sulfuric acid and its salt, particularly alkali metal salt and especially sodium salt, and hydroxycarboxylic acid such as citric acid and malic acid are applicable to reducing bleach.Preferred reducing agent is dithionite and sulphite, particularly sodium hydrogensulfite, and malic acid and citric acid.

According to wood base board of the present invention, preferred especially at first oxidation is the wood-fibred of reducing bleach then.

Oxidation bleaching very particularly preferably uses percarbonate or hydrogen peroxide to carry out, and reducing bleach uses sulphite, malic acid or citric acid to carry out.

In bleaching process, favourable program for 90-150 ℃ and up to 3 the crust pressure under in countercurrent tower, handle 5-40 weight % concentration continuously with the aqueous solution or the dispersion of bleaching agent moisture wood-fibred dispersion.Usually, this program is carried out in the presence of complexant such as EDTA to avoid transition metal ions to cause the degraded of bleaching agent.

Under the situation of the preferred embodiment of the wood base board according to the present invention, the bleaching of fiber is carried out in plate production, especially under MDF/HDF plate situation.Bleaching agent can be added in the fragment in preheater or the boiling vessel.Preferably also add complexant.

In principle, all can be obtained from the fibre of plant material and all can be used as base material according to wood base board of the present invention.Therefore, except that normally used wood-fibred, the fiber that for example is obtained from palm is what be fit to.Preferred substrates is light die model, especially dragon spruce or pine tree, but also can use more dark-coloured die model such as beech.

In the particularly preferred embodiment of the wood base board according to the present invention, the bleaching wood-fibred is used in combination with Chinese white making beating dyeing.Can improve whiteness fatefully like this.Yet also can carry out separately with Chinese white making beating dyeing.Obtain light plate in this case equally.

According to the present invention, term " Chinese white " comprises inorganic pigment and high light scattering plastics emulsion and gives the dispersion of whiteness, this inorganic pigment is titanium dioxide (rutile, C.I. Pigment white 6), calcium carbonate and mixture magnesium carbonate/calcium (as dolomite), zinc oxide, zinc sulphide, lithopone and sodium aluminum silicofluoride for example.Particularly preferred Chinese white is a titanium dioxide.Certainly also can use the mixture of Chinese white.

This Chinese white preferably uses with the form of aqueous dispersion, and wherein they exist with form in small, broken bits, because they can be introduced directly in the MDF/HDF production process via the spray tree lace individually or with glue with this form.

This pigment dispersion can comprise conventional auxiliary agent, especially wetting agent and dispersant, antifoaming agent and biocide in addition, also comprises antisettling agent, water-loss reducer and rheology modifier, and preferably by for example in agitating ball mill the wet-milling all components prepare.

The recommended density of Chinese white is generally based on dried fibres 0.5-15% in the wood base board of preparation, preferred 1-6%.

The further raising of whiteness can realize that this is because the blue fluorescence of their band (complementary color) has compensated graying and yellowing by adding fluorescent whitening agent.

In principle, the fluorescent dye that all turn blue, especially commercially available prod are for example

(BASF),

(Clariant) or

(Ciba), come from and comprise stilbene, distyrene biphenyl, cumarin and naphthalene diformazan imide, and be suitable via the chemical grade material of doubly linked benzoxazole and benzimidazole system.

Fluorescent whitening agent can be introduced in the MDF/HDF production process individually or with Chinese white and glue with the form of aqueous dispersion or solution.

If the use fluorescent whitening agent, its concentration in the wood base board of preparation is generally based on dried fibres 0.01-1%, preferred 0.08-0.2%.

According to wood base board of the present invention, wherein very particularly preferably in conjunction with all characteristics (bleaching wood-fibred, Chinese white and fluorescent whitening agent), this is because individual effect strengthens to obtain maximum overall whiteness by cooperative effect.

With regard to this process, very advantageously be preparation before injecting the MDF/HDF production process, to be added to by the spray tree lace glue at single aqueous dispersion Chinese white and fluorescent whitening agent together.

All can control in any variation aspect the physical property by the compacting wood base board that the method according to this invention causes by quality and the quantity of selecting adhesive.

Embodiment

Production according to MDF plate of the present invention

According to the standard of the color measurements of CIELAB, measure with by do not bleach wood-fibred and do not add Chinese white and equation of light Δ L that the MDF plate of the similar production of fluorescent whitening agent is compared as the whiteness tolerance of the plate of producing.

Embodiment 1

A) in 5l jar with anchor agitator and thermostatic control heating with 70g wood pulp (dragon spruce) and 1g ethylenediamine tetra-acetic acid (

BASF) in 3l water, be heated with stirring to 70 ℃.Stirred 1 hour down at 70-75 ℃ after adding the 7g SODIUM PERCARBONATE.Add 7g afterwards and connect sodium sulfite also at last 70-75 ℃ of further down the stirring 30 minutes.

Being cooled to after the room temperature, is to separate with liquid component on the screen cloth of 1mm and washing and thoroughly producing under circulating water tout court in mesh size with wood pulp.The filtrate that makes expansion then in the drying oven in complete alternation under 60 ℃ dry 3 days.

B) wood-fibred from the bleaching of step a) is mixed fully and with the glue batch of material injection of mentioning in the table 1 in paddle mixer.

Table 1

The glue batch of material
		Urea/melamine/formaldehyde resin, concentration 69 weight % in water	100.0 weight portion
The paraffin dispersion, concentration 60 weight % in water	4.1 weight portion
		Water	49.2 weight portion
		Solid resin content in the liquid	45％
Hard resin/dried fibres	14％
		The liquid of every 100kg dried fibres	31.1kg

The fiber that to use glue is then poured out obtaining piece, and cold prepressing is real and press down at 190 ℃ and to make plate.

Comparative Examples C1

Be similar to embodiment 1b) in the operation described produce the MDF plate by unbleached wood-fibred.

Embodiment 2

By unbleached wood-fibred (dragon spruce) and be similar to embodiment 1b) produce the MDF plate, that wood-fibred is mentioned with table 2 and comprise the glue batch of material injection of white pigment titanium dioxide.

Table 2

The glue batch of material
		Urea/melamine/formaldehyde resin, concentration 69 weight % in water	100.0 weight portion
The paraffin dispersion, concentration 60 weight % in water	4.1 weight portion
		The titanium dioxide preparation, concentration 70 weight % in water	39.4 weight portion
Water	9.8 weight portion
Solid resin content in the liquid	45％
		Hard resin/dried fibres	14％
Titanium dioxide/dried fibres	5.6％
		The liquid of every 100kg dried fibres	31.1kg

It is the whiteness (L represents with equation of light Δ) that standard reaches that table 3 has been listed based on Comparative Examples C1.

Table 3

Embodiment	ΔL
		1	12
2	10
		C1	-

Embodiment 3

To be equivalent in the spruce wood fragment in the sodium sulfite aqueous solution based on 40 weight % concentration of dried fibres 7.5% sodium hydrogensulfite is added to the MDF pilot-plant in MDF plate production process the boiling vessel.This MDF production process is continuous as usual, and output 21kg/h passes through the refiner de-fibering with fragment, and the glue batch of material that table 4 is mentioned is applied on the fiber that obtains continuously via the spray tree lace.

Table 4

The glue batch of material
		Urea/melamine/formaldehyde resin, concentration 66.5 weight % in water	100.0 weight portion
The paraffin dispersion, concentration 60 weight % in water	4.0 weight portion
		Water	33.8 weight portion
		Solid resin content in the liquid	48％
Hard resin/dried fibres	14％
		The liquid of every 100kg dried fibres	29.2kg

The wood-fibred of having used glue is dried to the about 9 weight % of remaining moisture content in the continuous dryer of downstream, and pours out then in batches and obtain piece, cold prepressing real and under 190 ℃ the press time coefficient compacting with 15s/mm obtain the thick plate of 16mm.

Comparative Examples C2

Be similar to the operation of describing among the embodiment 3 and produce the MDF plate, but do not add sodium sulfite.

Table 5 has shown that based on Comparative Examples C2 be the whiteness (L represents with equation of light Δ) that standard reaches.

Table 5

Embodiment	ΔL
		3	4
C2	-

Embodiment 4

There are the 40 weight % concentration sodium sulfite aqueous solution that are equivalent to based on dried fibres 4.5% sodium hydrogensulfite in mixer, to spray on dragon spruce wood chip apparatus.Then these fragments are sent in the boiling vessel of MDF pilot-plant.This MDF production process is continuous as usual, and output 21kg/h passes through the refiner de-fibering with fragment, and the glue batch of material of table 6 being mentioned and comprise white pigment titanium dioxide is applied on the fiber that obtains continuously via the spray tree lace.

Table 6

The glue batch of material
		Urea/melamine/formaldehyde resin, concentration 66.5 weight % in water	100.0 weight portion
The paraffin dispersion, concentration 60 weight % in water	4.0 weight portion
		The titanium dioxide preparation, concentration 70 weight % in water	47.5 weight portion
		Solid resin content in the liquid	44％
Hard resin/dried fibres	14％
		The liquid of every 100kg dried fibres	31.8kg

The wood-fibred of having used glue is dried to remaining moisture content in the continuous dryer of downstream be about 9 weight %, and pour out then in batches and obtain piece, at low temperatures pre-compacted and under 190 ℃ the press time coefficient compacting with 15s/mm obtain the thick plate of 16mm.

Comparative Examples C3

Be similar to the operation of describing among the embodiment 4 and produce the MDF plate, but do not add Chinese white (water with same quantity replaces the titanium dioxide preparation).

Table 7 has shown that based on Comparative Examples C3 be the whiteness (L represents with equation of light Δ) that standard reaches.

Table 7

Embodiment	ΔL
		4	6
C3	-

Embodiment 5

To be equivalent in the beech wood chip in the sodium sulfite aqueous solution based on 40 weight % concentration of dried fibres 6% sodium hydrogensulfite is added to the MDF pilot-plant in MDF plate production process the boiling vessel.This MDF production process is continuous as usual, and output 30kg/h passes through the refiner de-fibering with wood chip, and the glue batch of material that table 8 is mentioned is applied on the fiber that obtains continuously via the spray tree lace.

Table 8

The glue batch of material
		Urea/melamine/formaldehyde resin, concentration 66.5 weight % in water	100.0 weight portion
The paraffin dispersion, concentration 60 weight % in water	4.0 weight portion
		Water	47.5 weight portion
		Solid resin content in the liquid	44％
Hard resin/dried fibres	14％
		The liquid of every 100kg dried fibres	31.8kg

The wood-fibred of having used glue is dried to remaining moisture content in the continuous dryer of downstream be about 9 weight %, and pour out then in batches and obtain piece, at low temperatures pre-compacted and under 190 ℃ the press time coefficient compacting with 15s/mm obtain the thick plate of 16mm.

Embodiment 6

The glue batch of material mentioned in the use table 6 is produced the MDF plate, is similar to the operation of describing among the embodiment 5 but uses white pigment titanium dioxide.

Embodiment 7

The glue batch of material mentioned in the use table 9 is produced the MDF plate, is similar to the operation of describing among the embodiment 5 but is used in combination white pigment titanium dioxide and fluorescent whitening agent.

Table 9

The glue batch of material
		Urea/melamine/formaldehyde resin, concentration 66.5 weight % in water	100.0 weight portion
The paraffin dispersion, concentration 60 weight % in water	4.0 weight portion
		The titanium dioxide preparation, concentration 70 weight % in water comprise the commercially available fluorescent whitening agent of 2 weight %	47.5 weight portion
		Solid resin content in the liquid	44％
Hard resin/dried fibres	14％
		Titanium dioxide/dried fibres	5％
Fluorescent whitening agent/dried fibres	0.2％
		The liquid of every 100kg dried fibres	31.8kg

Comparative Examples C4

Be similar to the operation of describing among the embodiment 5 and produce the MDF plate, but do not add sodium sulfite.

Table 10 has shown that based on Comparative Examples C4 be the whiteness (L represents with equation of light Δ) that standard reaches.

Table 10

Embodiment	ΔL
		5	3
6	6
		7	7
C4	-

Claims (4)

1. light-coloured to white wood base board with Chinese white making beating dyeing, described wood base board is MDF plate, HDF plate or particieboard.

2. according to the wood base board of claim 1, wherein added fluorescent whitening agent.

3. according to the wood base board of claim 1 or 2, it is by the wood-fibred production of bleaching.

4. according to the wood base board of claim 1-3, it is by the at first oxidation bleaching wood-fibred production of reducing bleach then.