MOISTURE-CAPTURING, -STORING, AND/OR -RELEASING COMPOSITION

Abstract

The present invention relates to a composition comprising a first component being an inorganic mineral or mineral-like material having a porous structure, and a second component being a hygroscopic compound; a process for preparing such a composition; a composite material comprising a such a composition; a product comprising such a composition and/or composite material as well as a use of such a composition and/or a composite material as a flame retardant or as a humidity adjusting agent.

Claims

1. A composition comprising a first component being an inorganic mineral or mineral-like material having a porous structure, and a second component being a hygroscopic compound.

2. The composition according to claim 1, wherein the inorganic mineral or mineral-like material is a calcium carbonate-, magnesium carbonate-, calcium phosphate- and/or magnesium phosphate-containing material, and preferably a calcium carbonate- and/or magnesium carbonate-containing material, more preferably is a surface-reacted calcium carbonate or a hydromagnesite, and most preferably is a surface-reacted calcium carbonate.

3. The composition according to claim 2, wherein the surface-reacted calcium carbonate is a reaction product of natural ground calcium carbonate or precipitated calcium carbonate with carbon dioxide and one or more H.sub.3O.sup.+ ion donors, wherein the carbon dioxide is formed in situ by the H.sub.3O.sup.+ ion donors treatment and/or is supplied from an external source, preferably the at least one H.sub.3O.sup.+ ion donor is selected from the group consisting of hydrochloric acid, sulphuric acid, sulphurous acid, phosphoric acid, citric acid, oxalic acid, an acidic salt, acetic acid, formic acid, and mixtures thereof, and acidic salts thereof, and more preferably is phosphoric acid.

4. The composition according to claim 1, wherein the second component is present in anhydrous form, or wherein the second component is present in an at least partially hydrated form and/or dissolved form.

5.-6. (canceled)

7. The composition according to claim 1, wherein the hygroscopic compound is chosen from the group consisting of salts, polyalkylene glycols, polyols, silicon-containing compounds, urea, alpha-hydroxy acids, or polymers, more preferably is a hygroscopic salt, and most preferably is calcium chloride.

8. The composition according to claim 1, wherein the hygroscopic compound in its anhydrous form or partially hydrated form has a moisture pick-up susceptibility from 0.01 to 4.00 g[H.sub.2O]/g[compound], preferably from 0.01 to 3.0 g[H.sub.2O]/g[compound], more preferably from 0.25 to 2.5 g[H.sub.2O]/g[compound], even more preferably from 0.50 to 2.5 g[H.sub.2O]/g[compound], and most preferably from 1.0 to 2.0 g[H.sub.2O]/g[compound] at equilibrium capacity and at a relative humidity of 50% and at a temperature of +23° C. (±2° C.).

9. The composition according to claim 1, wherein the hygroscopic compound is present in an amount from 1.0 to 90 wt. %, preferably from 5.0 to 75 wt. %, more preferably from 7.5 to 60 wt. %, and most preferably from 10 to 40 wt. %, calculated from the dry weight of the hydroscopic compound and based on the total dry weight of the inorganic mineral or mineral-like material and the hygroscopic compound.

10. The composition according to claim 1, wherein the inorganic mineral or mineral-like material has a median particle size d.sub.50 from 1.0 μm to 100 μm, more preferably from 2.0 μm to 80 μm and most preferably from 3.0 μm to 40 μm and/or a specific surface area of from 20 to 200 m.sup.2/g, more preferably from 25 to 180 m.sup.2/g and most preferably from 30 to 100 m.sup.2/g as measured by the BET nitrogen method.

11. The composition according to claim 1, wherein the inorganic mineral or mineral-like material has an intra-particle intruded specific pore volume in the range from 0.1 to 2.3 cm.sup.3/g, more preferably from 0.4 to 1.8 cm.sup.3/g, and most preferably from 0.6 to 1.6 cm.sup.3/g, calculated from mercury porosimetry measurement.

12. The composition according to claim 1, wherein the composition has a total moisture content in the range from 1.0 to 90 wt. %, preferably from 2.5 to 75 wt. %, more preferably from 5.0 to 60 wt. %, and most preferably from 10 to 50 wt. %, based on the total weight of the composition.

13. A process for preparing the composition of claim 1, the process comprising the steps of: a) providing a first component being an inorganic mineral or mineral-like material having a porous structure, b) providing a second component being a hygroscopic compound c) mixing the first component of step a) with the second component of step b), d) optionally drying the mixture obtained in step c).

14. The process according to claim 13, wherein step c) refers to one or more solid blending step(s), and preferably the second component of step b) is provided in anhydrous form or in partially hydrated form, or wherein step c) refers to one or more impregnating step(s), and preferably the first component of step a) is provided in solid form or in form of an aqueous suspension, more preferably in solid form, and preferably the second component of step b) is provided in liquid form, more preferably in form of an aqueous solution.

15. The process according to claim 13, wherein the process further comprises the steps of: f) providing a coating and/or encapsulating agent g) mixing the coating and/or encapsulating agent of step f) with the mixture obtained in step c) or d).

16. A composite material comprising a composition according to claim 1.

17. The composite material according to claim 16 further comprising one or more materials selected from polymers, organic fibres, binders or resins, and preferably the composite material further comprises a resin or a combination of a resin and organic fibres.

18. A product comprising the composition according to claim 1.

19. A product according to claim 18, wherein the composition and/or the composite material is present throughout the whole product or is only present in at least one part of the product, preferably in a surface or surface-near layer of the product.

20. The product according to claim 19, wherein the product is a wood-based board, a humectant or a desiccant, and preferably a wood-based board, more preferably a fibre or particle board, and most preferably a particle board, a high-density fibre (HDF) board, medium-density fibre (MDF) board, low-density fibre (LDF) board, an oriented strand board (OSB), a hardboard, or an insulation board.

21. Use of a composition according to claim 1 as a flame retardant or as a humidity adjusting agent, preferably as desiccant or humectant.

22. The use according to claim 21, wherein the flame retardant is part of a flame resistant product, preferably a flame resistant wood-based board, more preferably a flame resistant fibre or particle board, and most preferably a particle board, a high-density fibre (HDF) board, medium-density fibre (MDF) board, low-density fibre (LDF) board, oriented strand board (OSB), hardboard, or an insulation board.

Description

FIGURES

[0349] FIG. 1: Moisture-capturing and -storing of the inventive composition 1 at 50% relative humidity (50%) and 90% relative humidity (90%) at 25° C. over a period of 100 min compared with a surface-reacted calcium carbonate SRCC1 not being impregnated with a hygroscopic compound (50% and 90%). The “moisture uptake” refers to the amount in gram of captured moisture/water per gram of composition.

[0350] FIG. 2: Moisture-capturing and—storing of the inventive composition 1 at 50% relative humidity (50%) and 90% relative humidity (90%) at 25° C. over a period of three days compared with a surface-reacted calcium carbonate SRCC1 not impregnated with a hygroscopic compound (50% and 90%). The “moisture uptake” refers to the amount in gram of captured moisture/water per gram of composition.

[0351] FIG. 3: Heat release rate of the inventive product (particle board P13 and P14 comprising the inventive composition 1 as flame retardant) and comparative products over time in a fire resistance test according to ISO 5660-1, Prüfung zum Brandverhalten.

[0352] FIG. 4: Total heat release rate and total mass loss of the inventive product (particle board P13 and P14 comprising the inventive composition 1 as flame retardant) and comparative products over time in a fire resistance test according to ISO 5660-1, Prüfung zum Brandverhalten.

[0353] FIG. 5: Extinction coefficient measured for the inventive product (MCI; MDF comprising the inventive composition 1 as flame retardant) and comparative products over time in a fire resistance test according to ISO 5660-1, Prüfung zum Brandverhalten.

[0354] FIG. 6: Carbon monoxide (smoke) development measured for the inventive product (MCI; MDF comprising the inventive composition 1 as flame retardant) and comparative products over time in a fire resistance test according to ISO 5660-1, Prüfung zum Brandverhalten.

[0355] FIG. 7: Water-capturing and water-storing potential of inventive compositions 2a (10%), 2b (20%) and 2c (30%) in comparison with surface-reacted calcium carbonate SRCC2 not being dry blended with calcium chloride. The “moisture uptake” refers to the amount in gram of captured moisture/water per gram of composition.

EXAMPLES

[0356] 1. Preparation of the Inventive Composition

[0357] 1.1 Materials

[0358] A) First Component: Surface-Reacted Calcium Carbonate (SRCC)

[0359] a) SRCC1 has a d.sub.50=4.44 μm, a d.sub.98=11.0 μm, a SSA=54.7 m.sup.2g.sup.−1 and an intra-particle intruded specific pore volume of 0.807 cm.sup.3/g (for the pore diameter range of 0.004 to 0.47 μm).

[0360] SRCC1 was prepared according to the following procedure: SRCC1 was obtained by preparing 350 litres of an aqueous suspension of ground calcium carbonate in a mixing vessel by adjusting the solids content of a ground limestone calcium carbonate from Omya SAS, Orgon having a weight-based median particle size of 1.3 μm, as determined by sedimentation, such that a solids content of 10 wt %, based on the total weight of the aqueous suspension, is obtained.

[0361] Whilst mixing the slurry at a speed of 6.2 m/s, 11.2 kg phosphoric acid was added in form of an aqueous solution containing 30 wt % phosphoric acid to said suspension over a period of 20 minutes at a temperature of 70° C. After the addition of the acid, the slurry was stirred for additional 5 minutes, before removing it from the vessel and drying using a jet-dryer.

[0362] b) SRCC2 has a d.sub.50=6.6 mm, d.sub.98=13.7 mm, SSA=59.9 m.sup.2g.sup.−1 with an intra-particle intruded specific pore volume is 0.939 cm.sup.3/g (for the pore diameter range of 0.004 to 0.51 μm). SRCC2 was obtained by preparing 350 litres of an aqueous suspension of ground calcium carbonate in a mixing vessel by adjusting the solids content of a ground limestone calcium carbonate from Omya SAS, Orgon having a mass based median particle size of 1.3 μm, as determined by sedimentation, such that a solids content of 10 wt.-%, based on the total weight of the aqueous suspension, is obtained.

[0363] Whilst mixing the slurry at a speed of 6.2 m/s, 11.2 kg phosphoric acid was added in form of an aqueous solution containing 30 wt.-% phosphoric acid to said suspension over a period of 20 minutes at a temperature of 70° C. After the addition of the acid, the slurry was stirred for additional 5 minutes, before removing it from the vessel and drying using a jet-dryer.

[0364] B) Second component: Calcium chloride

[0365] a) Calcium chloride 1: 42% calcium chloride in aqueous solution

[0366] b) Calcium chloride 2: Pelletized CaCl.sub.2) (anhydrous, granular, mm, ≥93%.

[0367] Sigma-Aldrich, Switzerland) was ground to particles 0.2 mm using a high speed rotor mill (Ultra Centrifugal Mill ZM 200, Retsch GmbH, Haan, Germany).

[0368] 1.2 Preparation process of the inventive composition

[0369] A) Inventive composition 1:

The inventive composition 1 was obtained by performing the following steps:
a) Providing surface-reacted calcium carbonate SRCC1 in solid form
b) Providing calcium chloride in form of an 42% calcium chloride aqueous solution (Calcium chloride 1)
c) Impregnating the surface-reacted calcium carbonate of step a) with the aqueous calcium chloride solution of step b) by placing 623 g of the surface-reacted calcium carbonate (TP2760/2) in a Lödige Mixer and adding 335 g of 42 wt. % CaCl.sub.2) aqueous solution using a funnel, while steering the surface-reacted calcium carbonate with a constant speed of 400-900 rpm. 958 g of the inventive composition with a final content of 18 wt. % CaCl.sub.2) on surface-reacted calcium carbonate (dry/dry) was obtained.
d) Drying the product obtained in step c) in a drying chamber overnight at 130° C.

[0370] B) Inventive Composition 2:

The inventive composition 2 was obtained by performing the following steps:
a) Providing surface-reacted calcium carbonate SRCC2 in solid form,
b) Providing calcium chloride in anhydrous form (Calcium chloride 2),
c) SRCC2 was weighed into a 0.5 l bottle (PE-LD, Semadeni, Germany) and the calcium chloride 2 was added to obtain the indicated loading of calcium chloride for inventive composition 2a to 2c. The bottle was immediately closed and the components were dry blended by mixing in a Turbula® Shaker Mixer (Glen Mills Inc, Clifton N.J., USA) for 2 min. Approximately 100 ml was transferred into a 600 ml beaker (150 mm diameter) and covered with filter paper for testing (see section 1.3.B, Test 2). The remaining powder mixture was closed and the PE bottle sealed with parafilm.

[0371] Three different inventive compositions were prepared according to the process above:

Inventive composition 2a: 10 wt. % of calcium chloride
Inventive composition 2b: 20 wt. % of calcium chloride
Inventive composition 2c: 30 wt. % of calcium chloride

Dry Mass

[0372] Dry mass was determined using a Halogen Moisture Analyzer (HB43-S, Mettler Toledo, Switzerland) drying at 200° C.

[0373] 1.3 Moisture-Capturing and -Storing Capability of the Inventive Compositions

[0374] A) Test 1

Moisture-capturing tests were performed to determine the moisture-capturing and -storing potential for the surface-reacted calcium carbonate as described in 1.1. A) a), i.e. the SRCC1 alone, and for the inventive composition 1 as obtained by the process described in 1.2. A).

[0375] Samples of both batches were placed in Petri dishes and dried over night at 105° C. The samples were kept under 2 different humidity conditions:

[0376] 50% relative humidity in a climate controlled laboratory at 25° C.

[0377] 90% relative humidity in a desiccator in the laboratory at 25° C.

[0378] The sample weight was recorded overtime. After three days the samples were dried over night at 105° C. and the experiment was repeated.

[0379] The results for moisture capturing and storing are shown in FIG. 1 for a timescale of 100 minutes and in FIG. 2 for a timescale of 3 days.

[0380] FIG. 1 shows that during the first 100 minutes the samples in 50% relative humidity (rH) absorb more moisture than the samples kept in 90% rH. The samples under 50% rH were kept in the open laboratory with laboratory air currents rather than the limited space desiccator where the atmosphere needs to keep replenishing by diffusion of moisture as the sample takes up the moisture in this static local atmosphere. FIG. 2 shows how, over the period of 3 days, the comparative surface-reacted calcium carbonate SRCC1 has only taken up a small amount of moisture when kept at 50% rH. The moisture capturing is slightly more pronounced when the comparative sample is kept at 90%. In comparison thereto, the inventive composition 1 has captured and stored a significant higher amount of water during the first 100 minutes as well as over the period of 3 days. When kept at 50% rH, the inventive composition 1 has reached an equilibrium at 0.35 g(water)/g(composition). This means that for 1 g of inventive composition 1 (of which 18 wt. % is CaCl.sub.2)) 0.35 g of moisture has been taken up into the composition. At this state, the inventive composition 1 is still a free flowing powder, which is easy to handle.

[0381] B) Test 2

The covered beakers containing inventive composition 2a to 2c were kept in a climate chamber (KBF LQC 240, Binder, Germany) in the dark at 25° C. with 60% relative humidity.

[0382] FIG. 7 shows the water-capturing and water-storing of inventive compositions 2a (10%), 2b (20%) and 2c (30%) in comparison with surface-reacted calcium carbonate SRCC2 not being dry blended with calcium chloride.

2. Use of the Inventive Composition as a Flame Retardant—Manufacturing of Composites Comprising the Inventive Composition and Evaluation of Fire Resistance

2.1 Example 1

[0383] 2.1.1 Manufacturing of a Particle Board Comprising the Inventive Composition as Flame Retardant

[0384] Different types of particle boards with partial substitution of wood particles by flame retardant were manufactured in lab scale (Table 1.). Surface layer (fine) and core layer (gross) wood chips were used for production of three layered particleboard. The MUF adhesive was provided by BASF AG under the name Kauramin Leim 620 flüssig. The amount of adhesive applied in each board and other manufacturing parameters are given is in Table 1.

TABLE-US-00001 TABLE 1 Particle board variants manufactured according to parameters given in Table 2 and by applying flame retardants as defined in Table 3. Pressing Core layer Surface layer Flame factor (CL) glue (SL) glue Glue retardant Wood Label (sec/mm) (%) (%) type * substitution Panel 1 15 15 15 MUF EcoChem 10% SL, 0% CL Panel 2 15 15 15 MUF EcoChem 10% SL, 0% CL Panel 3 15 15 15 MUF EcoChem 10% SL, 10% CL Panel 4 15 15 15 MUF EcoChem 10% SL, 10% CL Panel 5 15 15 15 MUF — — Panel 6 15 15 15 MUF — — Panel 7 15 30 30 MUF MSC 20% 15.06704 Panel 8 15 30 30 MUF MSC 20% 15.06704 Panel 9 15 25 25 MUF MSC 20% 15.06704 Panel 10 15 25 25 MUF MSC 20% 15.06704 Panel 11 15 20 20 MUF MSC 20% 15.06704 Panel 12 15 20 20 MUF MSC 20% 15.06704 Panel 13 15 15 15 MUF MSC 20% 15.06704 Panel 14 15 15 15 MUF MSC 20% 15.06704 * as defined in Table 3

TABLE-US-00002 TABLE 2 Lab scale manufacturing parameters for particle boards Plate dimensions 400 × 400 × 15.2 mm Ratio of SL/CL/SL 25/50/25 (mass-based) Target density 650 Kg/m3 Solid content of MUF resin 69.5% Hardener (Ammonium sulfate) 1% (40% w/w water solution) based on solid resin Resinated particles with 14% (based on dry wood) target moisture content

TABLE-US-00003 TABLE 3 Type of flame retardant used as partial substitute in particle board manufacturing EcoChem Commercially available flame retardant in powder form by EcoChem ® Inventive composition 1 Surface-reacted calcium carbonate powder SRCC1 impregnated with 18 wt. % (dry/dry) calcium chloride salt as described in example section 1.2.A having an equilibrium moisture content as shown for a rH of 50% in FIG. 2.

[0385] The wood particles were placed in a drum blender (rotation speed: 110 U/min) and the adhesive was applied with a sparing nozzle (air pressure: 2 bars). After application of the adhesive/glue the resinated particles were mixed for 5 more minutes. Then, the flame retardant was added and the mixture was blended for 5 min. Hot-pressing of the particle boards was performed on a laboratory press (HLOP210, Höfer Presstechnik GmbH) at 220° C. After production, the boards were left to cool down overnight.

[0386] 2.1.2 Fire Resistance Performance of Particle Board Comprising the Inventive Composition 1 as Flame Retardant

[0387] Board samples were conditioned at a temperature of 23±2° C. and a relative humidity of 50±5% until they reached a constant mass according to DIN EN 13238.

[0388] The board samples were then tested according to ISO 5660-1, Prüfung zum Brandverhalten—Teil 1: Heat release rate (Cone-Calorimeter method) and smoke development (dynamic measurement), using a board sample with dimensions of 100 mm×100 mm and a heat flux density of 50 kW/m.sup.2. Back and edges of samples were sealed with aluminum foil with thickness of 0.02 mm.

[0389] The test results for the heat release rate, total heat release rate and the total mass loss as shown in FIG. 3 and FIG. 4 demonstrate that the particle boards comprising the inventive composition 1 as flame retardant (P13 and P14) perform at least as good as the particle boards comprising the commercially available flame retardant (EcoChem).

2.2 Example 2

[0390] 2.2.1 Manufacturing of medium density fiberboard comprising the inventive composition 1 as flame retardant

[0391] Five different medium density fiberboards were provided for subsequent fire resistance tests (Table 4)

TABLE-US-00004 TABLE 4 Medium density variants for fire resistant tests MDF variant [abbreviation] Comment MDF comprising the Flame retardant is a surface- inventive composition reacted calcium carbonate 1 [MCI] powder impregnated with 18 wt. % (dry/dry) calcium chloride salt as described in example section 1.2.A having an equilibrium moisture content as shown for a rH of 50% in FIG. 2. MDF comprising EcoChem is a commercially EcoChem [Eco] available flame retardant by EcoChem ® MDF comprising CaCl.sub.2 MDF manufactured with 50% [CaCl2] CaCl.sub.2 salt solution added directly to the fiber during manufacturing process in an amount corresponding to the CaCl.sub.2 amount of the inventive composition 1 REF [REF] Control board without flame retardant B1-MDF[B1 MDF Commercially available MDF-E1- B1 panels (Tavapan)

[0392] Industrial grade wood fibers were weighted and moisture content was determined. Fibers were placed in a Lüdige mixer where 15% (dry on dry fiber) resin MUF Kauramin 627 BASF with solid content of 68% was applied. In addition, Ammonium sulfate hardener and hydrophobing agent Hydrowax 730 von Sasol Wax was applied on fiber.

[0393] Flame retardant was added to the wood fibers as a substitute to the fibers in an amount of 15 wt. % for the MDF variant comprising EcoChem flame retardant and 35 wt. % for the MDF variant comprising the inventive composition 1 (dry/dry).

[0394] The fibers were pressed to a panel using the Höfer hot press using a pressing time of 12 s and a temperature of 220° C. to a final thickness of 15.2 mm and a target density of 700 kg/m2. B1 MDF board was a commercially available panel obtained on free market.

[0395] 2.2.2 Fire resistance performance of MDF comprising the inventive composition 1 as flame retardant MDF samples were conditioned at a temperature of 23±2° C. and a relative humidity of 50±5% until they reached constant mass according to DIN EN 13238. The samples were then tested according to ISO 5660-1, Prüfung zum Brandverhalten—Teil 1: Heat release rate (Cone-Calorimeter Method) and smoke development (dynamic measurement), using sample with dimensions of 100 mm×100 mm and a heat flux density of 50 kW/m.sup.2. Back and edges of samples were sealed with aluminum foil with thickness of 0.02 mm.

TABLE-US-00005 TABLE 5 Test results for MDF variants Sample type as REF CaCl2 Eco MCI MCI B1-MDF B1-MDF defined in Table 4 (2) (2) (2) (1) (2) (1) (2) Maximum extinction 0.4/0.4 1.5 1.4/0.5 0.9 0.9 1.5/1.4 1.4/0.6 coefficient (1/m) Total smoke 40 70 590 90 80 1080 1040 release (m.sup.2/m.sup.2)

[0396] The results in Table 5 and FIGS. 5 and 6 show a superior performance of the two MDF boards (MCI) comprising the inventive composition compared to the other tested boards Eco and B1 MDF. The superior performance is demonstrated by the lower extinction coefficient (which is a measure for smoke development). Overall, the MDF boards comprising the inventive composition as flame retardant are characterized by significantly lower smoke development when compared to the boards manufactured with the commercially available flame retardant (Eco) as well the commercially available B1 MDF board obtained on the market. In addition, carbon monoxide yield is significantly lower for the MDF boards comprising the inventive composition as flame retardant and is in the range for the control board (REF) while the values for the boards with the commercially available flame retardant (Eco) and for the commercially available board (B1 MDF) are almost double.