WO2008129113A1

WO2008129113A1 - Improved composite product, adhesive product and method for the preparation of the same

Info

Publication number: WO2008129113A1
Application number: PCT/FI2007/000104
Authority: WO
Inventors: Jarmo Hukkanen; Kaino Virtanen
Original assignee: Jarmo Hukkanen; Kaino Virtanen
Priority date: 2007-04-23
Filing date: 2007-04-23
Publication date: 2008-10-30

Abstract

The invention is related to a composite product that consists of fibre material, a binding agent that keeps it together and additives. The binding agent is water glass and the product furthermore contains mineral substance, preferably graphite that works as a fire resistant material and increases the water resistance. The invention is furthermore related to a method of preparing a composite product. In a preferable embodiment the fibre material and graphite are mixed well together. Wall paper glue or wood adhesive is added to this mixture, after which the mixture is again mixed and dry water glass is added after which the mixture is again mixed. Water is added to get the desired rigidity of the mixture, with which it can be regulated and then the mixture is poured into a form and compressed to desired density. The composite product according to the invention may be a board product or a product in some other, 3-dimensional formation.

Description

IMPROVED COMPOSITE PRODUCT, ADHESIVE PRODUCT AND METHOD FOR THE PREPARATION OF THE SAME

TECHNICAL FIELD

The invention is related to an improved composite product, which consists of fibre material, a cohesive binding agent, and additives. The invention is also related to an improved adhesive product. Furthermore, the invention is related to methods for preparation of the composite product and the adhesive product.

TECHNICAL BACKGROUND

Prior known particle boards and plywood boards contain resin as binding agent, which is harmful for the environment. The problem with those is that different harmful gases, for example formaldehyde, are spread from them to the indoor air of the building.

Therefore, more environmentally friendly alternatives have been tried to develop. Water glass is an environmentally friendly substance, which is known from other connections. Its water resistance is, however, not especially good and therefore there are certain problems related to its use. A known technique that improves the water resistance of water glass is addition of pigments and metal salts. Heat treatment combined with washing with acids has also been tried, as well as glyoxal treatment (Kirk Othmer (1997), vol. 22, p. 23). However, the strength and endurance of such products has not been sufficiently good.

A further problem related to the prior art fibre products is their poor or lacking fire resistance. This problem relates to both board products and other, 3-dimensional composite products made of fibre.

THE OBJECT TO THE INVENTION The object of the invention is to obtain a composite product, with which said disadvantages of prior art products are avoided or reduced. Especially, the object of the invention is to achieve a composite product, such as a board product or a fibre product with 3-dimentional form, which is fire resistant, sufficiently strong and manufactured of pure natural materials, which do not contain substances that are harmful for the environment or humans.

SUMMARY OF THE INVENTION

The invention is based on a discovery that water glass and mineral substance, such as graphite, together give good water resistance and fire resistance for a composite product comprising fibres. The invention is further based on a discovery that a good adhesion and impregnation of the fibres is achieved by further using solvent, such as dimethyl sulphoxide in the production of the composite product, whereby good strength and endurance of the composite product is achieved.

The composite product of the invention consists of fibre material, a cohesive binding agent and additives, and it is characterized in that water glass is used as binding agent and in that the product comprises mineral substance, preferably graphite, as a substance that increases fire and water resistance, and that the product also comprises solvent, such as dimethyl sulfoxide. A method for producing a composite product according to the invention is characterized by preparing a composite product using at least said materials.

The invention also concerns an adhesive product, which is characterized in that the product comprises water glass, mineral substance, which works as a fire resistant material and as a substance that increases the water resistance, and solvent. A method for producing an adhesive product according to the invention is characterized by preparing the product using at least said materials.

The preferred embodiments of the product and method are presented in the dependent claims.

The fibre material can consist of for example wood particles, wood chips, veneer, peat, flax or hemp. The fibre material most preferably consists of natural fibre.

The invention suits well for the production of board products, such as particle board, peat board or plywood type board. The invention is also very suitable for the production of composite products of other, 3-dimensional forms. Examples of such products are car parts, such as buffers and dashboards, which can thus be made of natural, harmless materials, and still it is possible to achieve very high strength and endurance for the product. The composite products may also comprise flax or hemp as the fibre material. The behaviour of such products are also safer in e.g. car components because no sharp projections are formed in a car collision.

In a preferred embodiment of the method of the invention, fibre material and graphite are used, which are mixed well with each other. Wallpaper glue or wood adhesive is added in this mixture if such glue is used after which the mixture is mixed again, and water glass is added as dry material, after which the mixture is mixed again. Water and solvent is added to achieve desired rigidity, by which rigidity can be regulated, and then the mixture is poured to a form and pressed to desired density.

The compression temperature is preferably 180° - 200⁰C and the compression pressure is ca 32 bar, with which the desired density is achieved. However, the compression temperature can be substantially reduced by adding zinc oxide into the product.

For example, when preparing wooden particle board according to the invention, the wood material used for preparing a particle board can be e.g. ca 70 - 90 vol. -% saw dust or chips, 3-10 vol. -% water glass as dry material, preferably 8 - 9 vol.-%, 2,5 - 14 vol. -% graphite, preferably 5,5 vol.-%, 2-6 vol.-% wall paper glue or wood adhesive, and 5-15% solvent, such as dimethyl sulfoxide, DMSO, which is biologically degradable.

Graphite and water glass are non-flammable natural materials, which are harmless for humans and the nature. Furthermore, water glass hinders decay and moulding, so thanks to such a fire resistant material, other wood preservatives and mould preservatives are no more necessarily needed.

Gypsum can also be used in the invention as a fire resistant material. This at the same time increases the rigidity and strength of the product. In addition, the price of a fire resistant material containing such a substance is economic.

Also wallpaper glue can be used in the product of the invention. The wall paper glue (starch) is a water-soluble natural material, which is economic and environmentally friendly and does not contain harmful substances for humans and the nature. Alternatively wood adhesives can be used instead of wall paper glue. A preferred embodiment of a particle board according to the invention contains in addition to the chips as main components ca 5-15 vol. -% water glass, (if the humidity of the water glass is 53%), 2,5-14 vol. -% graphite and 2-6 vol. -% wallpaper glue or wood adhesive, 5-15 % solvent, and when desired, additives in accordance with the sub claims. If dry water glass is used, the amount of it is ca 2-10 vol. -%.

It is preferable to add 0,5-5%, preferably 1-3% zinc oxide by weight. The zinc oxide improves the drying of water glass, and thus lower processing temperatures can be used. Zinc oxide also improves the water resistance of the product.

In tests, it has also been noticed that the water resistance of water glass can in the invention especially advantageously be improved by adding to the composition a little amount of calcium sulphate (gypsum) or lithium carbonate or lithium chloride or titanium sulphate. In a particle board, it is also preferable to use titanium oxide (TiU₂) as a substance that increases the water resistance. The additions of salts have to be done so that the water glass is as homogeneous as possible after the additions. The homogenisation can be improved by means of rigorous agitation and grinding as well as heating. Also a little particle size of the additive improves the homogenBation. Thus, the formulation, with which the board is done, can contain a little amount of additives that improve the water resistance (0,01-5 %), such as lithium salts and/or lithium compounds, titanium salts and/or titanium compounds, calcium salts and/or calcium compounds and other corresponding additives.

It is also advantageous to include a small amount, such as 0.1-2%, of wax, preferably dry natural wax in the product. This further improves the water/moisture resistance of the product.

It is also possible to use the mixture of the invention without fibres as an adhesive product as such. Such an adhesive products has same advantages as the composite product; good water resistance, fire resistance, strength and endurance. Such an adhesive product is not harmful to the environment or humans, as the components of the product are natural/biodegradable materials. The adhesive product can be made with same mutual proportions of water glass, mineral substance, such as graphite, and solvent, such as dimethyl sulfoxide DMSO, possible wallpaper glue or wood adhesive as the composite product, except that the adhesive product itself does not comprise fibres as its main component. Same additives can be used in the adhesive product as in the composite product. Also, the function of each component is similar as described in relation to the composite product.

EXAMPLES

In the following, the invention is described by means of some example applications.

EXAMPLE 1

Particle boards were prepared at VTT (Technical Research Centre of Finland) of surface and middle-layer particles delivered by Koskinen Oy for use in the preparation of particle boards. The glue material used was according to the following formulation, a mixture of water glass (Huber Engineered Materials, sodium silicate Zeopol^® 22), graphite powder (delivered by the inventor) and wallpaper glue (bought from a store):

30 dl chips = 76 vol. -% 6 dl sodium silicate = 15,2 vol. -% 2 dl graphite = 5 vol. -% 1 ,5 dl wallpaper glue = 3,8 vol. -%

The density and dry material content of the materials to be used in the formulation were determined so that the substances of the glued particle mass could be calculated as absolute masses before compression. These are presented in table 1.

Table 1. Densities of used materials

In the following text wall paper glue also means wood adhesives, which have same properties as the wall paper glue in comparison.

As the water content of the glued mass was more than 50 % of weight of the dry matter content with the sodium silicate addition according to the formulation, the dry matter of the wallpaper glue (4 grams of carboxyl methyl cellulose) was added directly to the sodium silicate without preparing any water solution.

With this formulation two doses of glued mass was prepared, half of which consisted of outer-layer particles for a particle board and the other half consisted of middle-layer particles. The particles were spread out over a plywood form with a surface area of 20 cm x 20 cm and with a height of 25 cm. The particles were spread out in such way that a half of the glued outer-layer particles were put first, then the middle-layer particles and onto that, the rest of the outer-layer chips. The compressed particle mats were pressed into boards in a temperature of 110° C. Overlong compression times (30 min 5 and 90 min) were used for the boards because of the high water content and for avoiding delamination, a 15 min. cooling time was furthermore performed after the compressbn. The boards were pressed to a thickness of 12 mm and the starting pressure of the compression was 35 bar.

The boards are marked with numbers 12 and 13 in the result table.

Table 2. The results of the boards made according to the basic formulation.

EXAMPLE 2

In this example, the wallpaper glue was left out from the formulation and two different water glass/graphite amounts were tested in relation to the particles. With the change in the formulation, there was strived both to a decreased total amount of particles in the board and to a decreased water content to be closer to a normal level (12-13 %), because it is difficult to control the compression of a board in a higher water content. It was also strived to achieve a typical board density, 680 kg/m³. Table 3. Compositions of the formulations 1 and 2

There were 42% of outer-layer particles and 58 % of middle-layer particles within the particles to be glued. The whole formulations have been presented in figures 3 and 4. In figures 3 and 4 there have also been presented examples of board formulations of prior art.

The boards were pressed to a goal thickness of 12 mm and the calculated density was 680kg/m ³. A low density automatically decreases the IB-value. Boards 4 and 5 were close to the goal thickness and also the best IB-results were achieved with board numbers 4 and 5, which were pressed in 80⁰C and which had a cooling step of 10 minutes and which had been made with formulations 1 and 2.

In the basic formulation, the relation between the graphite and the particles (formulations 4 and 5) was still changed and the test was repeated with the conditions of board number 5 (best IB).

In addition, the water resistance of the boards was tried to improve by using as additive, in formulation 4, 1 % TiO2 and LJ2C03 of weight of water glass. The additive in formulation 6 was gypsum (CaS04) which is a by-product of chemical producer Kemira Oyj. All these substances inproved the water resistance of the board.

Table 5. The compositions of formulations 4, 5 and 6

Particles vol. -% Water glass vol. -% Graphite vol. -%

Formulation 4 90 6 4

Formulation 5 80 12 8

Formulation 6 77 15 5(+gypsum 3 vol. -%)

A high temperature improves the water resistance of water glass, why a separate heat treatment was tried for one of the samples. A new test piece was taken from the earlier prepared test board 5, which was kept in 200⁰C in an oven for one hour. The swelling was tested from the test piece after the heat treatment. The swelling was only 4,6 %.

Table 7. Preparation of compressed boards

According to the results, the heat treatment improved the swelling result of a board that earlier did not stand water so that the swelling after the heat treatment was only 4,6 %. This result has to be considered to be very good. Such a conclusion should either not be drawn from the results that the heathg would affect the IB-vaϋe in a worsening manner as the heat treated samples are located in the middle of the board and had already been used earlier.

STUDYING RESULTS

The following conclusions can be drawn from the composition and the test results of those: - The swelling and IB (13% and 0,52 Mpa) of a board made with the two first formulations were close to the goal even without a separate heat treatment

The swelling can be considerably improved with the heat treatment (200⁰C, 1 h)

PREPARATION EXAMPLE 2

Particle boards were prepared according to the following formulation: 30 dl particles = 82,2 vol.-%

4 dl sodium silicate = 11 voI.-%

1 dl graphite = 2,7 vol.-%

1 ,5 dl wallpaper glue = 4,1 vol.-%

The mixture was thorough^ mixed for ca ten minutes until a composition with a solid and uniform mass was obtained and from which a cohesive board could be prepared. The mass was then placed in a form for preparation of a board. Baking paper was placed at the upper and lower surfaces of the board to avoid adhesion and the mass was compressed by pressing. The form was thereafter placed in an electric oven for 15 minutes in a temperature of 200⁰C. Thereafter, it was taken out from the oven and dried to a final dryness. The board hardened and the result was a cohesive board.

PREPARATION EXAMPLE 3

Particle boards were prepared according to the following formulation: 30 dl cutter chips = 83,3 vol. -% 1 dl graphite = 5,5 vol. -%

3 dl dry matter water glass (= sodium silicate) = 8,3 vol. -% 1 ,5 dl wallpaper glue = 2,8 vol. -%

The dry-materials are first mixed together. It is important that the cutter chips and the graphite are mixed well and that the graphite does not stay at the bottom of the vessel. Then the wallpaper glue is added and mixing is performed again. The water glass dry matter is added next, and mixing is performed again. Water is added last, with which the rigidity of the mixture can be regulated. The mixture is poured in a form in which it is compressed to the desired density. Baking paper has to be put between the press jaws or the like so that the mass would not fasten to the jaws. The compression temperature has to be 180-200 °C so that the dry water glass would melt.

This composition was found to be the best one in view of the final board. The board was not too moist and it was very cohesive. Its fire resistance properties are the same as those of boards 4 and 5, as the compound amounts correspond to each other.

PREPARATION EXAMPLE 4

Particle boards were prepared according to the following formulation: 30 dl cutter chips = 76,9 vol. -% 1 dl graphite = 5,1 vol. -% 1 dl gypsum = 2,6 vol. -%

6 dl water glass = 15,4 vol. -% Result: Stands in water without being destroyed. If the amount of gypsum is increased with 50 % the board is not cohesive at all.

COMPARISON EXAMPLE 1 30 dl cutter chips 18O g (=3 dl) graphite

200 g (=1 ,5 dl) blast furnace 11 water glass = 22,5 vol. -%

Result: too moist, too much water glass.

COMPARISON EXAMPLE 2 30 d I cutter chips 2 dl graphite 1 dl wallpaper glue 1 I water glass (=15,4 vol-%)

Result: a little better water resistance, but not really good.

COMPARISON EXAMPLE 3

A particle board was prepared from the following composition in the same way.

Particle boards were prepared with the following formulation:

30 dl cutter chips = 76,9 vol. -%

7 dl sodium silicate = 18 vol. -% 2 dl graphite = 5,1 vol. -%

The board handened but stayed moist. There is too much water glass, in other words sodium silicate, in this board.

FIRE-RESISTANCE TEST

The fire resistance tests were performed at VTT Building and Transport department with particle board samples, done with formulations 4 and 5 (see example 2 above).

During the period 3.7.2002-5.8.2002, the samples were kept in a space with a temperature of 23°C and the relative humidity was 50 %. According to the follow-up of the weight of the samples, the samples reached a constanthumidity during the conditioning.

The fire resistance properties of the samples were studied 5.8.2002 by using a calorimeter according to standard ISO 5660.

5 The results of the test in view of heat development and smoke formation of the sample have been presented for board 4 and board 5 in figure 2. The characteristics describing the test results are the following:

1) The fire effect per surface area of the sample (kW/m²), which describes how strongly the sample develops heat when burning, in other words the strength of o the burning of the sample.

2) The smoke formation speed (RSP, m²/s), that describes how much smoke the sample forms during the test.

The heat development of board 4 is in the beghning of the test clearly lowerthan the heat development of a corresponding wood sample without any fire protection. 5 From this it can concluded that the sample would be classified quite well in a classification test. The fire technical behaviour of building tools according to classification [1] concerning the heat development would probably be B, when it would be D with the reference sample.

The heat development of board 5 is in the beginning of the test a little lower than the0 heat development of a corresponding wood sample without any fire protection used as reference sample. From this it can be concluded that the sample wood be classified in the same way as the reference sample. Thus, the fire technical behaviour of building tools in accordance with the heat development of classification [1] would probably be D. 5 On the basis of the results, the heat development of board 4 is better than that of board 5.

According to the results, the smoke formation speed of boards 4 and 5 does not deviate so much with respect of classification from the smoke formation speed of the reference sample.

The tests were repeated using approx. 10% dimethyl sulfoxide DMSO as solvent and 1-3% zinc oxide as additive in producing the products of the above examples. The solvent substantially improves the absorption of the product components and additives into the fibre material. As a result the strength and water resistance of the composite product is much improved while the good fire resistance properties are maintained. By adding zinc oxide it was possible to use lower processing temperature in order to achieve same results. Zinc oxide causes the water glass to dry in a lower temperature, and thus a temperature as low as 80-100 ⁰C could be used. Water resistance was also increased when zinc oxide was added. The water/moisture resistance could also be increased by adding 1 % of dry natural wax in the product.

The invention is not restricted to the above preferable embodiments of usage, but can vary in scope of the invented idea determined by the patent claims.

For example, although graphite has been mentioned as one mineral substance to be used as a mineral component of the product, also other alternatives exist. For example, also other form of carbon can be used as a mineral substance instead of graphite. However, it has appeared that carbon black does not have optimal fire resistance properties in the product according to the invention.

Also, even if dimethyl sulfoxide, DMSO has been described as the preferable solvent in producing the product, it is possible to use alternatively some other corresponding solvent. However, it is preferable that the solvent is biologically degradable.

One should also note that even if the examples above have related board products, the invention is just as suitable for the production of composite products which may have any 3-dimensional form. And even if the examples have related to using wood as fibre material, it is also possible to use other fibre materials, such as flax, peat or hemp for producing the product. [1]= Collection of building Rules in Finland, part E1 : Fire safety of building Rules and instructions 2002, Helsinki: Ministry of Environment 200240 p. (The degree of the Ministry of environment government of the fire safety of buildings given 12.3.2002.)

Claims

1. Composite product, which comprises fibre material, a binding agent that keeps it together, and additives, characterized in that the product comprises:

- water glass as binding agent, - mineral substance, which works as a fire resistant material and as a substance that increases water resistance, and

- solvent .

2. A composite product according to claim 1 , characterized in that the fibre material is wood particles, wood chips, veneer, peat, flax or hemp.

3. A composite product according to claim 1 or 2, characterized in that it is a particle board, peat board or plywood type board.

4. A composite product according to claim 1 or 2, characterized in that it has a 3-dimensional formation.

5. A composite product according to any previous claim, characterized in that the mineral substance is graphite or another form of carbon.

6. A composite product according to any previous claim, characterized in that it contains 10-30 vol.-% graphite, preferably 12 vol.-%.

7. A composite product according to any previous claim, characterized in that the product contains gypsum, which works as a water resistance giving substance.

8. A composite product according to any previous claim, characterized in that the product contains 0,2-5%, preferably 1-3% zinc oxide as an additive.

9. A composite product according to any previous claim, characterized in that the product contains a little amount (0,01-10%) of other additives, which improve the water resistance, such as lithium salts and/or such compounds, titanium salts and/or such compounds, calcium salts and/or such compounds, wax, such as dry natural wax, or other corresponding additives.

10. A composite product according to any previous claim, characterized in that water soluble wood adhesive and/or wall paper glue is used as a binding agent to increase the strength.

11. A composite product according to any previous claim, characterized in that it contains 3-60 vol.-% water glass, preferably 25 vol.-% with a humidity of 63 %.

12. A composite product according to any previous claim, characterized in that it contains 2-15 vol.-% dry matter water glass, preferably 8-11 vol.-%.

13. A product according to any of the previous claims, characterised in that it contains 8-12 vol.-% wall paper glue and/or wood adhesives.

14. A product according to any of the previous claims, characterised in that the amount of the solvent is 1-20%, preferably 5-15% and most preferably 10% in volume.

15. A product according to any of the previous claims, characterised in that the solvent is biologically degradable.

16. A product according to any of the previous claims, characterised in that the solvent is dimethyl sulfoxide DMSO.

17. Method of preparing a composite product that comprises fibre material, a binding agent that keeps it together and additives, characterised in that the product is produced using at least following components: fibre material, water, water glass, mineral substance and solvent.

18. A method according to claim 17, characterized in that the method comprises steps, in which: a) fibre material and graphite as mineral substance are mixed well together, b) wallpaper glue and/or wood adhesive is added to the mixture of step a), after which the mixture is again mixed, c) water glass as dry matter is added, after which the mixture is again mixed, d) mixture of water and water glass is added to achieve desired rigidity, e) solvent is added, f) the mixture is poured into a form, and g) compression to desired density is performed.

19. A method according to claim 17 or 18, characterised in that the compression temperature is 80-200 C for wood and peat material, and 80-122 C for plywood type material.

20. A method according to any of claims 17-19, characterised in that the compression pressure is 18-22 bar for plywood made of birch, and 10-22 bar for plywood made of softwood.

21. A method according to any of claims 17-20, characterised in that the fibre material used is cutter chips, chips, peat, flax or hemp for preparing the composite product.

22. A method according to any of claims 17-21 , characterised in that 50-70 vol.-% fibre material, 2-15 vol.-%, preferably 10-12 vol.-% dry water glass, 10-30 vol.-%, preferably 12 vol.-% graphite, 5-15 vol.% solvent, 8-12 vol.-% wallpaper glue or wood adhesives are used in the preparation of the mixture.

23. A method according to any of the previous claims, characterised in that the solvent is biologically degradable solvent, preferably dimethyl sulfoxide DMSO.

24. A method according to any of claims 17-22, characterised in that 0,1-5%, preferably 1 -3% of zinc oxide is used as an additive.

25. Adhesive product, characterized in that the product comprises:

- water glass, - mineral substance, which works as a fire resistant material and as a substance that increases the water resistance, and

- solvent.

26. An adhesive product according to claim 24, characterized in that the mineral substance is graphite or another form of carbon.

27. An adhesive product according to claim 25 or 26, characterised in that the solvent is biologically degradable.

28. An adhesive product according to any of claims 25-27, characterised in that the solvent is biologically degradable, preferably dimethyl sulfoxide DMSO.

29. An adhesive product according to any of claims 25-28, characterized in that water soluble wood adhesive and/or wall paper glue is used as a binding agent to increase the strength.

30. An adhesive product according to any of claims 25-29, characterized in that the product contains 1-10%, preferably 2-5% zinc oxide as an additive.

31. An adhesive product according to any of claims 25-30, characterized in that the product contains a little amount (0,01-10%) of other additives, which improve the water resistance, such as lithium salts and/or such compounds, titanium salts and/or such compounds, calcium salts and/or such compounds, wax, such as dry natural wax, or other corresponding additives.

32. Method of preparing an adhesive product, characterised in that the product is produced using at least following components: water glass, mineral substance and solvent.

33. A method according to claim 32, characterized in that the mineral substance is graphite or another form of carbon.

34. A method according to any of claim 32 or 33, characterised in that the solvent is biologically degradable, preferably dimethyl sulfoxide DMSO.