EP0958330A1

EP0958330A1 - Fireproofing agent for particle or fibre boards

Info

Publication number: EP0958330A1
Application number: EP97925009A
Authority: EP
Inventors: Herbert G. Nopper; Hubert F. Schmidt
Original assignee: Sud-West-Chemie GmbH
Current assignee: Sud-West-Chemie GmbH
Priority date: 1996-05-30
Filing date: 1997-05-28
Publication date: 1999-11-24
Also published as: BR9709375A; CA2256398A1; DE19621606A1; WO1997046635A1; AU3030197A

Abstract

The invention concerns a fireproofing agent which can be applied to boards or shaped parts of particles or fibres, obtained from wood or components of annual plants, in order to render them fireproof. The fireproofing agent according to the invention contains between 65 and 85, preferably 74, parts by weight ammonium sulphate, between 10 and 25, preferably 19, parts by weight borax and between 4 and 10, preferably 7, parts by weight trisodiumphosphate. In addition, between 0.5 and 2 parts by weight, preferably 1 part by weight, sodium metasilicate can be added. The invention further concerns a method of fireproofing boards or shaped parts of this type. According to this method, the particles or fibres are first impregnated with a solution of the fireproofing agent according to the invention, are then dried to a moisture content of between approximately 1 % and approximately 12 %, preferably between 1 and 4 %, are subsequently glued with a binder, combined to form pressed mats, and finally compressed to form boards or shaped parts.

Description

FIRE PROTECTION AGENT FOR CHIP OR FIBER PANELS

description

The invention relates to a fire protection agent for boards or molded parts made of chips or fibers, which were obtained from wood or components of annual plants, and to such boards and molded parts containing such a fire protection agent. The invention further relates to a method for fire-resistant equipping of such plates or molded parts.

Sheets or molded parts of the type mentioned are generally highly flammable. Due to their material properties, however, they are used in a variety of ways as a material, for example in furniture construction, in the interior construction of buildings and in motor vehicles. In many possible uses, however, the easy flammability of the chipboard or fiberboard and molded parts, which results from the easy flammability of the organic raw materials used, interferes. Especially in the construction industry, for safety reasons, efforts are being made to use only flame-retardant or fire-resistant materials.

In the past, attempts have repeatedly been made to make wood-based panels and panels made from renewable raw materials fire-retardant or fire-resistant. For this purpose, it was proposed, for example, in DE 31 44 773 A1 to apply an aqueous solution of inorganic salts to a wood chip granulate which is to be pressed into a wood chip molded body, and then to glue and compress the granulate. In order to be able to produce wood chip moldings that are not only fire-retardant, but fire-resistant or even highly fire-resistant, it has so far been necessary in any case to additionally apply a fire-resistant layer to the surfaces of the wood chip moldings.

The invention is therefore based on the object of proposing a fire protection agent with which plates or molded parts made of chips or fibers, which are made of Wood or components of annual plants have been obtained, can be made fire-resistant. Furthermore, it is an object of the invention to provide panels and molded parts of the type mentioned which are fire-resistant or highly fire-resistant and to propose a method for fire-resistant finishing of panels or molded parts of the type mentioned. The proposed fire protection agent must be compatible with the usual binders for gluing the chips or fibers and must not develop smoke gases harmful to health under the influence of flames.

This object is achieved according to the invention with a fire protection agent which contains 65 to 85, preferably 74 parts by weight of ammonium sulfate, 10 to 25, preferably 19 parts by weight of borax and 4 to 10, preferably 7 parts by weight of trisodium phosphate. The sheets and moldings proposed according to the invention contain this fire protection agent.

The method according to the invention for the fire-resistant finishing of panels or molded parts of the type mentioned at the beginning comprises the following method steps:

- The chips or fibers are impregnated with a solution of the proposed fire protection agent,

the impregnated chips or fibers are dried to a moisture content of approximately 1% to approximately 12%, preferably 1 to 4%,

the impregnated and dried chips or fibers are glued with a binder,

- The impregnated, dried and glued chips or fibers are combined to press fleeces and then pressed into sheets or molded parts.

The proposed fire protection agent is a mixture of inorganic salts which contain no chlorides and are not toxic. It is compatible with all known condensation and polymerization resins, for example urea, melamine and phenol formaldehyde resins, epoxy resins, novolak resins, PMDI resins, etc. In addition, it does not cause harmful gases to evaporate from the finished plate or the finished one Molding.

The ammonium sulfate contained in the proposed fire protection agent promotes the surface charring of cellulose through the formation of sulfuric acid. Borax puffs up when heated and has an additional disinfectant effect; it also serves as a melt flux when pressing the press tile. The trisodium phosphate also contained in the fire protection agent decomposes from 75 ° C to NaOH and P ₂ 0 ₅ ; it has emulsifying, water softening and buffering properties.

By mixing these three salts in the ratio given, a fire protection agent is obtained with which plates or molded parts made of chips or fibers, which have been obtained from wood or components of annual plants, can be made fire-resistant.

An advantageous development of the fire protection agent according to the invention is that an additional 0.5 to 2 parts by weight, preferably 1 part by weight, of sodium metasilicate is added. Sodium metasilicate has a water-softening effect, has a wetting agent effect and a disinfectant effect and releases water when heated. If it is added to a solution of the fire protection agent, it serves as a wetting agent and thus promotes the wetting of the chips or fibers with the fire protection agent. An advantageous side effect is the fungicidal and insecticidal properties that the fire retardant obtains by adding the sodium metasilicate.

The proposed fire protection agent is best used when it is in an aqueous solution, the solution concentration being 20 to 50%, preferably 30 to 35%. With such an aqueous solution, the chips or fibers can be impregnated with the fire protection agent and thus impregnated even before being instructed and pressed into sheets or molded parts.

To solve the further problems, plates or molded parts made of chips or fibers, which were obtained from wood or parts of annual plants, which contain the above-mentioned fire protection agent according to the invention are proposed. This fire protection agent can comprise ammonium sulfate, borax and trisodium phosphate in the mixture ratios indicated above or, as an advantageous further development, additionally contain sodium metasilicate.

These panels or molded parts have the best flame-retardant properties if the ratio between the dry matter of the proposed fire protection agent and the dry matter of the chips or fibers is 0.1 to 0.4, preferably 0.2.

According to the invention, fire-resistant plates or molded parts are produced from chips or fibers using the method described in claim 11. A solution of the proposed fire protection agent is therefore used to pre-impregnate the chips or fibers with which the chips or fibers are impregnated. The fire protection agent can contain the salt mixture specified in claim 1 or the salt mixture described in claim 2. The fire protection agent is preferably present in an aqueous solution with a concentration of 20 to 50%, preferably 30 to 35%. The chips or fibers can be pre-impregnated with the fire protection agent in an immersion bath or by injecting the fire protection agent into a continuous mixer or a mixing screw. The density of the fire protection agent solution used is preferably approximately 1.2 g / cm ³ , it having a pH in the slightly alkaline range, preferably approximately 8.5.

To glue the chips or fibers, these must usually not exceed a moisture content of approx. 12%. Therefore, after impregnation with an aqueous fire protection agent solution, it is necessary to dry the impregnated chips or fibers. After drying, the impregnated chips or fibers have a pH of approx. 3.5 to 4.5.

Urea or melamine resins are preferably used for gluing the chips or fibers impregnated with the fire protection agent. This offers the great advantage that the ammonium sulfate contained in the fire retardant dissociates during the pressing of the chips or fibers due to the resulting heating and acts as a hardener for the binder. The addition of a separate hardening substance is therefore unnecessary. In the case of chips or fibers made of straw, however, PMDI resins are preferably used as binders.

The result of the method according to the invention consists of plates or molded parts made of chips or fibers which are fire-resistant to highly fire-resistant, without it being necessary to apply an additional flame-retardant coating. The invention is explained further below using two examples.

Example 1:

Pine wood chips were obtained in a known manner by machining round wood, so that their length was 5 to 15 mm, their width 2 to 4 mm and their thickness 0.2 to 0.5 mm. These chips were pre-dried to a moisture content of approximately 30%.

A fire protection agent solution of the following composition was added to the predried chips in a continuous mixer.

50 parts by weight of water,

37 parts by weight of ammonium sulfate,

9.5 parts by weight of borax,

3.5 parts by weight of trisodium phosphate.

The ratio between the mass of the added fire protection agent solution and the dry mass of the chips was 0.6.

The impregnated chip was then dried in a drum dryer to a residual moisture of approx. 1% and metered into a glue mixer. An aqueous binder of the following composition was added to the impregnated chip in the glue mixer.

82.5 parts by weight of urea-formaldehyde liquid resin (65%), 5 parts by weight of paraffin emulsion (50%), 12.5 parts by weight of water.

In this process step, it was not necessary to add a hardener substance, since the dried, impregnated chip had a pH of 3.5 to 4 and the added fire retardant thus acted as a hardener when pressed. The ratio between the mass of the aqueous binder and the mass of the dried, impregnated chip was approximately 0.2. The glued chips were sprinkled into a fleece and pressed into a particle board for 3.4 minutes at a temperature of 180 ° C. with a pressing time factor of 10 sec / mm. The chipboard produced in this way had the following parameters:

Thickness: 20.4 mm

Density: 650 kg / m ³

Weight per m ² : approx.13.3 kg

Flexural strength: approx. 24 N / mm ²

Cross tensile strength (V 20): approx.0.42 N / mm ²

Cross tensile strength (V 100): approx.0.18 N / mm ²

Thickness swelling (2 h): approx.5.5%

The finished chipboard can be used as a furniture board in dry and damp rooms as well as outdoors according to DIN standards 68761 (parts 1 and 4), 68762, 68763 and 68800.

The fire-resistant equipment of the chipboard was tested by pointing the full flame of a Bunsen burner at a distance of 13.5 cm to the surface of the board, whereby the temperature was between 800 ° C and 1000 ° C. A flame treatment of 5 minutes could not cause the particle board to ignite. Only a surface charring was found; the smoke development was extremely low. The chipboard met the requirements of DIN standard 4102.

Example 2:

Wheat straw was chopped up to a length of 4 to 8 mm, a width of 0.5 to 2 mm and a thickness of about 0.15 mm. These straw fibers were mixed in a mixing screw with a fire protection agent solution of the following composition:

21 parts by weight of ammonium sulfate, 5.4 parts by weight of borax, 3 parts by weight of trisodium phosphate, 0.6 parts by weight of sodium metasilicate, 70 parts by weight of water. The ratio between the mass of the added fire protection agent solution and the dry mass of the straw fibers was 0.67.

The impregnated straw fibers were then freed of excess fire protection agent solution in a dewatering screw and then dried to a residual moisture content of approximately 4%.

PMDI resin was sprayed onto these straw fibers, so that a ratio between the mass of the PMDI resin and the dry mass of the straw fibers was 0.06.

The impregnated and glued straw fibers were sprinkled into a fleece, heated in a preheating station to a core temperature of approx. 60 ° C. and then for 4.4 minutes, at a temperature of 200 ° C. and with a pressing time factor of 15 sec / mm, pressed into a fiberboard. The finished fiberboard had the following parameters:

Thickness: 17.5 mm

Density: 550 kg / m ³

Weight per m ² : 9.6 kg

This fiberboard was also exposed to the flame of a Bunsen burner at a distance of 13.5 cm, so that a temperature between 800 ° C. and 1000 ° C. resulted on the surface of the plate. After a flaming time of 5 minutes, the plate experienced no change except for surface charring that developed without flame formation. There was only very little smoke development. The DIN standard 4102 was also met.

Claims

Fire retardant for boards or molded parts made of chips or fibers and process for fire-resistant finishing of such boards or molded parts

1. Fire retardant for boards or molded parts made of chips or fibers, which were obtained from wood or parts of annual plants, containing: 65 to 85, preferably 74 parts by weight of ammonium sulfate, (NH ₄ ) ₂ S0 ₄ ;

10 to 25, preferably 19 parts by weight of borax, Na ₂ B ₄ 0 ₇ ^• 10 H ₂ 0;

4 to 10, preferably 7 parts by weight of trisodium phosphate, Na ₃ P0 ₄ ^• 12 H ₂ 0.

2. Fire protection agent according to claim 1, characterized in that it additionally contains 0.5 to 2 parts by weight, preferably 1 part by weight of sodium metasilicate, Na ₂ Si0 ₃ ^• 9 H ₂ 0.

3. Fire protection agent according to one of claims 1 or 2, characterized gekenn¬ characterized in that it is dissolved in water.

4. Fire protection agent according to claim 3, characterized in that the solution has a concentration of 20 to 50%, preferably 30 to 35%.

5. A board made of shavings or fibers, which was obtained from wood or parts of annual plants, containing a fire protection agent with the following components:

65 to 85, preferably 74 parts by weight of ammonium sulfate, (NH ₄ ) ₂ S0 ₄ ;

6. Plate according to claim 5, characterized in that the fire protection agent additionally contains 0.5 to 2 parts by weight, preferably 1 part by weight sodium metasilicate, Na ₂ Si0 ₃ ^• 9 H ₂ 0.

7. Plate according to one of claims 5 or 6, characterized in that the ratio between the dry mass of the fire retardant and the dry mass of the chips or fibers is 0.1 to 0.4, preferably 0.2.

8. Shaped part made of shavings or fibers, which were obtained from wood or components of annual plants, containing a fire protection agent with the following components:

65 to 85, preferably 74 parts by weight of ammonium sulfate, (NH ₄ ) ₂ S0 ₄ .

9. Molding according to claim 8, characterized in that the fire protection agent additionally contains 0.5 to 2 parts by weight, preferably 1 part by weight sodium metasilicate, Na ₂ Si0 ₃ ^• 9 H ₂ 0.

10. Molding according to one of claims 8 or 9, characterized gekenn¬ characterized in that the ratio between the dry matter of the Brandschutz¬ means and the dry matter of the chips or fibers is 0.1 to 0.4, preferably 0.2.

11. Process for the fire-resistant finishing of boards or molded parts made of chips or fibers, which were obtained from wood or parts of annual plants, with the following process steps:

- The chips or fibers are impregnated with a fire protection agent solution, the dissolved components of which contain:

4 to 10, preferably 7 parts by weight of trisodium phosphate, Na ₃ P0 ₄ 12 H ₂ 0;

the impregnated chips or fibers are dried to a moisture content of about 1% to about 12%, preferably 1 to 4%,

the impregnated and dried chips or fibers are glued with a binder,

12. The method according to claim 11, characterized in that the most dissolved constituents of the fire protection agent solution additionally contain 0.5 to 2 parts by weight, preferably 1 part by weight of sodium metasilicate, Na ₂ Si0 ₃ ^• 9 H ₂ 0.

13. The method according to any one of claims 11 or 12, characterized gekenn¬ characterized in that the fire protection agent solution has a solution concentration of 20 to 50%, preferably 30 to 35%.

14. The method according to any one of claims 11 to 13, characterized gekenn¬ characterized in that the impregnation of the chips or fibers takes place in an immersion bath.

15. The method according to any one of claims 11 to 13, characterized gekenn¬ characterized in that the impregnation of the chips or fibers takes place in a continuous mixer or a mixing screw.

16. The method according to any one of claims 11 to 15, characterized gekenn¬ characterized in that the impregnated chips or fibers are freed from excess fire protection agent solution in a drainage screw.

17. The method according to any one of claims 11 to 16, characterized gekenn¬ characterized in that the fire retardant solution has a pH in the slightly alkaline range, preferably around 8.5.

18. The method according to any one of claims 11 to 17, characterized gekenn¬ characterized in that the impregnated and dried chips or fibers have a pH between 3.5 and 4.5.

19. The method according to any one of claims 11 to 18, characterized gekenn¬ characterized in that the binder consists of urea or melamine resins.

20. The method according to any one of claims 11 to 18, characterized ge indicates that PMDI resins are used as binders for chips or fibers made of straw.

21. The method according to any one of claims 11 to 20, characterized gekenn¬ characterized in that the press nonwovens at temperatures of 180 to 220 ° C and pressures of 150 to 300 N / cm ² are pressed into plates or mold parts.