WO2013017135A1 - Matière cellulosique comprenant un silicate de métal - Google Patents

Matière cellulosique comprenant un silicate de métal Download PDF

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Publication number
WO2013017135A1
WO2013017135A1 PCT/DK2012/050286 DK2012050286W WO2013017135A1 WO 2013017135 A1 WO2013017135 A1 WO 2013017135A1 DK 2012050286 W DK2012050286 W DK 2012050286W WO 2013017135 A1 WO2013017135 A1 WO 2013017135A1
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WO
WIPO (PCT)
Prior art keywords
metal silicate
cellulosic material
composition
liquid metal
wood
Prior art date
Application number
PCT/DK2012/050286
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English (en)
Inventor
Mette Bjerregaard BLOMGREEN
Michael ØSTERBY
Michael NØRGÅRD
Original Assignee
Bollerup Jensen A/S
Frøslev Træ A/S
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bollerup Jensen A/S, Frøslev Træ A/S filed Critical Bollerup Jensen A/S
Publication of WO2013017135A1 publication Critical patent/WO2013017135A1/fr
Priority to PCT/DK2013/050258 priority Critical patent/WO2014019590A1/fr
Priority to US14/418,637 priority patent/US20150183888A1/en
Priority to EP13752576.2A priority patent/EP2879848A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/20—Silicates
    • C01B33/32—Alkali metal silicates
    • C01B33/325—After-treatment, e.g. purification or stabilisation of solutions, granulation; Dissolution; Obtaining solid silicate, e.g. from a solution by spray-drying, flashing off water or adding a coagulant

Definitions

  • a cellulosic material comprising metal silicate
  • the present invention relates to a novel cellulosic material, such as wood, comprising a high content of a metal silicate positioned inside the cellulosic material.
  • Metal silicates are a group of compounds including sodium silicate, potassium silicate and lithium silicate.
  • Sodium silicate is the most widely used metal silicate, and is the common name for sodium metasilicate, Na 2 Si0 3 , also known as water glass or liquid glass. It is available in aqueous solution and in solid form and may find use in e.g. cements, passive fire protection, refractories, textile and lumber processing, and automobiles.
  • metal silicate and in particular sodium silicate can be used as e.g. a fire protective agent in wood preservation, such as in a paint composition or as an "impregnation" agent.
  • a fire protective agent in wood preservation, such as in a paint composition or as an "impregnation" agent.
  • the uptake of the metal silicate in the cellulosic material is limited, if any uptake happens at all.
  • WO 94/12289 discloses a method for using silicate compounds to create a surface protection of e.g. a wood article.
  • US 6,146,766 discloses a method for fire- protecting cellulosic material with sodium silicate. It is described that the method uses a combination of vacuum and pressure to penetrate cellular walls. Increased fire protection appears to be documented, however there are no data showing that the sodium silicate actually penetrates the materials. Furthermore, the chemical properties of the used sodium silicate are not further defined.
  • WO 2009/008797 discloses a method for strengthening wood structures comprising the use of a waterglass composition having a pH below 5. This document does not define any further details on the chemical properties of the composition used, besides the pH.
  • WO 2009/087262 discloses a method for impregnating wood or wood products, wherein said wood or wood products are initially pre-treated with the blue-stain fungus. Such pre-treatment should enhance the uptake of sodium silicate.
  • the present invention provides a different solution to the above problem.
  • a modified metal silicate composition for the preservation step positioning of the metal silicate inside the cellulosic structures is enhanced.
  • an object of the present invention relates to cellulosic materials comprising a high content if metal silicate.
  • one aspect of the invention relates to a cellulosic material comprising metal silicate
  • cellulosic material comprises metal silicate, and/or
  • said cellulosic material does not comprise viable or non-viable blue-stain fungus or tracers thereof.
  • Another aspect of the present invention relates to a process for providing a cellulosic material comprising metal according to the invention comprising
  • cellulosic material providing the cellulosic material comprising metal silicate.
  • liquid metal silicate has been subjected to a mechanical
  • Yet another aspect of the present invention is to provide a cellulosic material obtainable by a process according to the invention.
  • Figure 1 shows wood impregnated with modified low viscosity sodium silicate (top) and with non-modified low viscosity sodium silicate (bottom). It can be seen that only the modified sodium silicate penetrates into the wood board (darker colouring). For the non-modified sodium silicate are very thin dark colouring at the surface of the board is visible.
  • the board has the dimensions 2.54 cm X 10,16 cm (1 X 4 inches).
  • Figures 2-4 show state-of-the-art graphs in relation to sodium silicate dependency on solid content, ratio and temperature (textbook by J.G. Vail, Soluble Silicates Vol. 1, Reinhold, New York, 1952).
  • Figure 5 shows state-of-the-art knowledge in relation to the change in types silicates present in a sodium silicate composition when changing the Na : Si ratio.
  • Each line indicate a different type of silicate.
  • an aspect of the present invention relates to a cellulosic material
  • - comprising detectable metal silicate more than 1 mm from any surface of said material, such as more than 2 mm, such as more than 3 mm, such as more than 4 mm, such as more than 5 mm, such as more than 6 mm, such as more than 8 mm, such as more than 10 mm, such as more than 20 mm such as more than 30 mm, and/or - wherein at least 10%, such as at least 20%, such as at least 30%, such as at least 40%, such as at least 50%, such as at least 60% such as at least 70%, such as at least 80%, such as at least 90% or such as at least 95% of said cellulosic material is preserved with metal silicate, and/or
  • - comprising at least 50 kg metal silicate / m 3 of cellulosic material, such as at least 100 kg metal silicate / m 3 , such as at least 150 kg metal silicate / m 3 , such as at least 200 kg metal silicate / m 3 , such as at least 250 kg metal silicate / m 3 , such as at least 300 kg metal silicate / m 3 , such as at least 350 kg metal silicate / m 3 , such as at least 400 kg metal silicate / m 3 , such as at least 500 kg metal silicate / m 3 , such as at least 600 kg metal silicate / m 3 , such as at least 700 kg metal silicate / m 3 , such as at least 800 kg metal silicate / m 3 , such as at least 900 kg metal silicate / m 3 , such as in the range 50 kg to 2000 kg metal silicate / m 3 , such as, in the range 50 kg to 1800 kg metal silicate /
  • said cellulosic material does not comprise viable or non-viable blue-stain fungus or tracers thereof.
  • the presented aspect solves the problem of pre-treatment of the cellulosic material as previously described.
  • the above features describing the presence of the metal silicate in the cellulosic material all relates to the presence of metal silicate throughout a large proportion of the cellulosic material.
  • the amount of metal silicate present inside the cellulosic material may be determined by different methods:
  • Measurements of the distribution of metal silicate in the cellulosic material may be determined by electron microscopy. - The percentage of preserved cellulosic material may be determined as the amount of material wherein metal silicate can be determined.
  • the weight/weight ratio may be determined by measuring the dry weight of the cellulosic material before and after the preservation treatment, or by comparison to a reference level.
  • the cellulosic material comprises detectable metal silicate more than 1 mm from a surface of said material, wherein the surface is substantially parallel to vascular structures (such as xylem and/or phloem) in a wood board.
  • Unmodified metal silicate may be able to enter into wood structures from the "end" of a wood board, since the xylem and/or phloem provides space for the metal silicate.
  • the surface is position at least 10 cm away from a free "end" of a wood board, such as at least 30 cm such as at least 50 cm, such as at least 80 cm or such as at least 100 cm.
  • the amount of metal silicate which may penetrate wood structures through open "ends" is not significant since it may only impregnate a minor part of the board near the ends.
  • metal silicates exist and in the table below some types of metal silicates are listed.
  • the table shows examples of different types of sodium silicate and potassium silicate and their properties. These metal silicates may be used as starting materials for preparing the metal silicate composition of the present invention, as the first liquid metal silicate.
  • °Be Baume
  • GV weight/weight ratio between Si0 2 and Na 2 0 or between Si0 2 and K 2 0.
  • the metal silicate may be selected from the group consisting of sodium silicate, potassium silicate and lithium silicate.
  • the metal silicate may be selected from the group consisting of sodium silicate and potassium silicate, more preferably the metal silicate is sodium silicate.
  • Sodium silicate (water glass) is a member of the family of soluble sodium silicates and is considered the simplest form of glass.
  • Water glass is derived by fusing sand and soda ash; it is non-combustible with low toxicity. It may be used as catalysts and silica gels; soaps and detergents; adhesives; water treatment; bleaching and sizing of textiles and paper pulp; ore treatment; soil solidification; glass foam; pigments; drilling muds; binder for foundry cores and molds; waterproofing mortars and cements; and surface impregnating wood.
  • the cellulosic material may preferably have a volume of at least about 0.5 cm 3 , such as at least 1 cm 3 , such as at least 2 cm 3 , such as at least 5 cm 3 , such as at least 50 cm 3 , such as at least 500 cm 3 , such as at least 1000 cm 3 , such as at least 10000 cm 3 . It is to be understood that timber or boards may have a much larger volume.
  • the cellulosic material has a thicknes of at least 1 cm, such as at least 2 cm, such as as least 3 cm or such as in the range 1 to 10 cm.
  • cellulosic material refers to materials comprising cellulose, such as plywood, fiberboard and wood.
  • the cellulosic material according to the invention is wood.
  • wood refers to fibrous tissue found in many plants. It is an organic material, a natural composite of cellulose fibers (which are strong in tension) embedded in a matrix of lignin which resists compression.
  • wood It is common to classify wood as either softwood or hardwood.
  • the wood from conifers e.g. pine
  • the wood from dicotyledons usually broad-leaved trees, e.g. oak
  • hardwood usually broad-leaved trees
  • Wood may be further divided into heartwood and sapwood.
  • Heartwood is wood that as a result of a naturally occurring chemical
  • Heartwood may (or may not) be much darker than living wood. It may (or may not) be sharply distinct from the sapwood.
  • other processes, such as decay can discolor wood, even in woody plants that do not form heartwood, with a similar color difference, which may lead to confusion.
  • Sapwood is the younger, outermost wood; in the growing tree it is living wood, and its principal functions are to transport water from the roots to the leaves and to store up and give back according to the season the reserves prepared in the leaves. However, by the time they become competent to conduct water, all xylem tracheids and vessels have lost their cytoplasm and the cells are therefore functionally dead. All wood in a tree is first formed as sapwood.
  • said wood is hardwood or softwood or a combination thereof.
  • said wood comprises heartwood and/or sapwood.
  • said wood is sapwood, e.g. from pine.
  • wood materials according to the present invention are timber and lumber (boards) of different sizes and shapes.
  • a fire retardant material is one having properties that provide comparatively low flammability or flame spread properties.
  • materials that have been used to treat wood for fire retardancy including ammonium phosphate, ammonium sulfate, zinc chloride, dicyandiamide-phosphoric acid and sodium borate.
  • the solution to increasing the metal silicate concentration inside a cellulosic material is related to the liquid metal silicate composition and not pre-treatment of the cellulosic material as described in WO 2009/087262.
  • another aspect of the present invention relates to a process for providing a preserved cellulosic material according to the invention comprising
  • liquid metal silicate or cellulosic material is mechanically or chemically pre-treated, with the proviso that said cellulosic material is not biologically pre-treated, such as with blue-stain fungus.
  • liquid metal silicate composition is pre-treated.
  • liquid metal silicate composition is mechanically pre- treated (modified). Mechanical modification of a liquid metal silicate composition is also described in example 1.
  • liquid metal silicate compositions according to the present invention show uptake of higher concentrations of metal silicate into the cellulosic material, such as wood, compared to unmodified liquid metal silicate compositions (see example 2).
  • the term "into said cellulosic material” refers to the situation where the metal silicate according to the present invention is detectable inside the wood structure.
  • the metal silicate according to the present invention is detectable more than 1 mm into said cellulosic material, such as more than 2 mm, such as more than 3 mm, such as more than 4 mm, or such as more than 5 mm.
  • the term "onto said cellulosic material” refers to the situation where the metal silicate according to the present invention is only detectable on the surface of the cellulosic material.
  • the metal silicate according to the present invention is only detectable for at most 1 mm into said cellulosic material, such as at most 0.5 mm into said cellulosic material, e.g. at most 0.25 mm into said cellulosic material. It is to be understood by the mentioned distance, that it relates to the distance from any surface of said cellulosic material, wherein said surface is a surface visible to the human eye. Thus, a "surface” is not a microscopic surface present inside e.g. a wood structure, but relates to what would normally be considered the surface of e.g. a standard wood board. Thus, in an embodiment said surface is a visible surface.
  • modified liquid metal silicate composition (second metal silicate composition) of the present invention were able to penetrate the cellulosic material (the sapwood) and enter into the cellulosic material.
  • unmodified liquid metal silicate composition (a first metal silicate composition) was not able to enter into the cellulosic material but stayed onto the surface of the cellulosic material.
  • the viscosity of the liquid metal silicate composition of the present invention is relatively lower than an unmodified metal silicate composition, there may still be a high solid content.
  • the liquid metal silicate composition according to the invention has a solid content of the metal silicate in the range 0.5% - 80%, such as in the range 0.5% - 70%, such as in the rang, 0.5% - 60%, such as in the range, 0.5% - 50%, such as in the range, 0.5% - 40%, such as in the range, 0.5% - 30%, such as in the range, 0.5% - 20%, such as in the range 0.5% - 10%, such as in the range 0.5% - 5%, such as in the range 0.5% - 3%. Since this may also depend on the specific type of cellulosic material the user has to consider whether it is appropriate to dilute or concentrate the composition before use.
  • heart wood is denser in structure than sapwood it is more difficult to get the liquid metal silicate composition into heartwood compared to sapwood.
  • sapwood has a more open structure which may allow the metal silicate composition to penetrate more deeply into the structure.
  • Some cellulosic material, such as boards may comprise both heartwood and sapwood and they may not be equally modified with the liquid metal silicate composition.
  • heartwood is much more resistant to e.g. moisture and therefore also microorganisms such difference may not affect the overall preservation of the material.
  • the metal silicate composition may be positioned into or onto the cellulosic material by different means.
  • said positioning is performed by at least one of the methods selected from the group consisting of reduced pressure, e.g. vacuum, added pressure, dipping, brushing, spraying, and sap-, microwaving, high-frequency, and introduction of the sodium silicate composition in a supercritical state.
  • reduced pressure e.g. vacuum, added pressure, dipping, brushing, spraying, and sap-, microwaving, high-frequency, and introduction of the sodium silicate composition in a supercritical state.
  • composition according to the invention when used for wood preservation it may be advantageously to have other components added to the composition.
  • the process further comprises hardening said liquid metal silicate composition after the liquid metal silicate composition has been positioned into and/or onto said cellulosic material.
  • said hardening is provided by
  • a hardener such as an acid, C0 2 , bicarbonate, or one or more metal salt such as calcium chloride and/or zink chloride
  • the metal silicate will polymerize thus become water insoluble and subsequently be unable to leach from the material or perform a reduced leaching.
  • the problem with leaching may be less pronounced if the liquid metal silicate is positioned inside a cellulosic material such as a wood structure, opposed to standard positioning of the metal silicate where it will only be positioned on the surface of the cellulosic material, e.g. wood structure due to lack of penetration.
  • leaching refers to the loss of a part of the metal silicate composition from the cellulosic material over a period of time. Leaching may be due to rain or high moisture content in the surrounding environment.
  • hardening refers to the situation where the metal silicate composition or part of the metal silicate composition is stabilized. Hardening may be by polymerization of the metal silicate which reduces the water solubility and makes it difficult for the metal silicate to leach from the cellulosic material.
  • Another possible process to avoid or reduce leaching may be to combine heating and reduced pressure, e.g. vacuum.
  • said hardening process is performed under reduced pressure, e.g. vacuum, at a temperature in the range 45-85°C.
  • said temperature is in the range 55-85°C, such as 65-85°C, or such as 75-85°C.
  • said temperature is in the range 45-75°C, such as 45-65°C, or such as 45-55°C.
  • the advantage of the reduced pressure, e.g. vacuum is that the effect of heating at standard pressure may be obtained at a lower temperature. This is an advantage for cellulosic material, e.g.
  • said reduced pressure or vacuum is in the range 0.1-0.9 bar, such as 0.20-0.90 bar, such as 0.30-0.90 bar, such as 0.40-0.90 bar, such as 0.50-0.90 bar, such as 0.60-0.90 bar, such as 0.70-0.90 bar, or such as 0.80-0.90 bar.
  • said reduced pressure or vacuum is in the range 0.1-0.8 bar, such as 0.10-0.70 bar, such as 0.10-0.60 bar, such as 0.10-0.50 bar, such as 0.10-0.40 bar, such as 0.10-0.30 bar, or such as 0.10-0.20 bar.
  • said hardening process takes place for 10 minutes to 24 hours, such as 1-24 hours, such as 3-24 hours, such as 5-24 hours, such as 8-24 hours, such as 12-24 hours, such as 16- 24 hours, or such as 20-24 hours.
  • said hardening process takes place for 10 minutes to 20 hours, such as 1-16 hours, such as 1-12 hours, such as 1-8 hours, or such as 1-4.
  • said reduced pressure, e.g. vacuum is in the range 1-90% vacuum and said temperature is in the range 45-85°C.
  • said hardening process is performed for 30 minutes to 24 hours, such as 0-24 hours.
  • the liquid metal silicate composition is in the range 0.1-0.8 bar, such as 0.10-0.70 bar, such
  • the liquid metal silicate composition which may be used to provide a cellulosic material according to the present invention has novel properties.
  • the invention relates to a novel composition comprising a liquid metal silicate composition such as sodium silicate, potassium silicate and/or lithium silicate having a lower viscosity than a corresponding type of liquid metal silicate.
  • the invention relates to a liquid metal silicate composition, having a viscosity of 45 mPa.s or less measured at 20°C at a solid content of 39% or about 39% of said metal silicate, in an aqueous solution.
  • the term "about” refers to a deviation of the solid content in the percentages of +/- 2%, such as +/- 1.5%, such as +/- 1%, such as +/- 0.5%.
  • Different factors influencing viscosity of a liquid metal silicate such as the mole ratio, solid content and temperature. Thus, if a change in viscosity is needed, at least one of the mole ratio, solid content or temperature could be adjusted.
  • compositions according to the present invention also covers compositions with a solid content different from 39%, compositions with temperatures different from 20°C and compositions which are not in an aqueous solution.
  • the 39% solid content, the 20°C temperature and the aqueous solution simply relate to the condition under which the viscosity should be measured. The person skilled in the art would know how to change these conditions to match these criteria.
  • the compositions according to the invention may have different solid contents, different temperatures and be solubilised in different solutions, which may result in a lower or higher viscosity, however when adjusted to the conditions defined herein, the skilled person is capable of evaluating if the viscosity falls within the scope of the present invention, having a viscosity of 45 mPa.s or less.
  • the metal silicate composion according to the present invention has a solid content of the metal silicate in the range 5-60%, such as 10-60%, such as 15-60%, such as 20-60%, such as 30-60%, such as 10-50%, such as 10- 40%, such as 10-30%, or such as 10-20% metal silicate.
  • the viscosity of such compositions may still be measured at 20°C at a solid content of about 39% of said metal silicate, in an aqueous solution.
  • the viscosity of the liquid metal silicate according to the invention may vary depending on the specific purpose.
  • the viscosity at 20°C at a solid content of about 39% of said metal silicate, in an aqueous solution is in the range 1-45 mPa.s, such as 1-43 mPa.s, such as 1-41 mPa.s, such as 1-39 mPa.s, such as 1-35 mPa.s, such as 1-30 mPa.s, such as in the range 1-25 mPa.s, such as 1-20 mPa.s, such as 1-15 mPa.s, such as 1-10 mPa.s.
  • the viscosity at 20°C at a solid content of about 39% of said metal silicate, in an aqueous solution is in the range 5-45 mPa.s, such as 10-45 mPa.s, such as 15-45 mPa.s, such as 15-43 mPa.s, such as 15-41 mPa.s, such as 15-39 mPa.s, such as in the range 20-39 mPa.s, such as 25-39 mPa.s, or such as 28-39 mPa.s.
  • the viscosity at 20°C at a solid content of about 39% of said metal silicate, in an aqueous solution is in the range 5-15 mPa.s, in the range 10-20 mPa.s, in the range 15-25 mPa.s, in the range 20-30 mPa.s, in the range 25-35 mPa.s, in the range 30-40 mPa.s, or in the range 35-45 mPa.s.
  • viscosity is measured by a Brookfield viscosimeter at 20°C. Said viscosity is measured at average sea-level pressure, such as 101.325 kPa, e.g. using a Brookfield viscosimeter model LVT-DVII, serienr. 017141.
  • the liquid metal silicate according to the invention may have different pHs depending on the purpose, however preferably the pH is alkaline. Thus, in another embodiment the liquid metal silicate composition has a pH in the range 8.5-14, such as 9-14, such as 11-14 or such as 12-14. At such elevated pHs the
  • composition is stable for long periods of time
  • the liquid metal silicate composition has a pH in the range 1-5, such as 1-4.5, such as 1-4, such as 2-4, such as 2.5-4, or such as 3.5- 4.
  • the liquid metal composition according to the invention may be defined by the ratio between the viscosity and the solid content of the metal silicate.
  • the invention relates to a liquid metal silicate composition characterized in that said composition has a ratio between the viscosity and the solid content of said metal silicate of less than 1.150, such as less than 1, such as less than 0.8, or such as less than 0.6.
  • the viscosity is measured as mPa.s and the solid content is measured as (w/w) on dry matter % of the metal silicate. Dry matter is a measurement of the mass percentage of the matter when completely dried relative to the un-dried matter.
  • the viscosity of metal silicates also depend on the weight/weight ratio between the metal and the silicate, such as the Si0 2 to Na 2 0 ratio and Si0 2 to K 2 0 ratio.
  • the weight/weight ratio between the silicate and the metal is above 0.50, e.g. above 0.75, such as above 1, e.g. above 1.25, such as above 1.50, e.g. above 1.70, e.g. above 2, such as above 2.25, e.g. above 2.50, such as above 2.75, e.g. above 3, e.g. in the range of 20 to 1, such as 6 to 1, such as 5 to 1, such as 4 to 1 such as 3.30 to 1.58.
  • Agent for preserving cellulosic material is above 0.50, e.g. above 0.75, such as above 1, e.g. above 1.25, such as above 1.50, e.g. above 1.70, e.g. above 2, such as above 2.25, e.g. above 2.50, such as above 2.75, e.g. above 3, e.g. in the range of 20 to 1, such as 6 to 1, such as 5 to 1, such as 4 to 1 such as 3.30 to 1.58.
  • a composition according to the invention may find use in many applications.
  • composition is an agent for preserving cellulosic material, such as wood.
  • the terms "preservation”, “preserved” or “preservation agent” relates to an improvement of cellulosic material compared to a control material without metal silicate.
  • An enhancement may be in relation to fire protection, attacks from insects such as termites, and attacks from microorganisms, such as fungus and bacteria.
  • the cellulosic material according to the invention is preserved with metal silicate.
  • the process according to the invention relates to a process for providing a cellulosic material preserved with a metal silicate.
  • a further benefit of providing enhancement according to the present invention is the benefit on the environmental safety due to non-toxicity of the composition relative to other known fungicides and fire retardant components.
  • composition according to the invention is capable of maintaining a reduced viscosity over a long period of time, preferably, without having to take special precautions.
  • said viscosity is stable for at least 2 hours, at least 10 hours, at least 1 day, at least 2 days, at least 5 days, at least 20 days, at least 40 days, such as at least 60 days, or such as at least 90 days.
  • the improved properties of the liquid metal silicate composition of the present invention may be provided by the process of producing the composition.
  • Another aspect relates to a process for producing a liquid metal silicate composition comprising the steps of:
  • Yet an aspect of the present invention relates to a liquid metal silicate composition obtainable by a process according to the present invention.
  • a preferred embodiment of the present invention relates to a process for producing a liquid metal silicate composition according to the invention comprising a) providing a first liquid metal silicate composition,
  • a second liquid metal silicate composition having a viscosity of 45 mPa.s or less measured at 20°C at a solid content of about 39%, in an aqueous solution, and
  • first metal silicate composition relates to any metal silicate composition
  • second metal silicate composition relates to a metal silicate composition which has been subjected to a process according to the invention. As described under c) such process may be repeated to further modify the composition.
  • Yet an aspect of the present invention relates to a liquid metal silicate composition obtainable by a process according to the present invention.
  • compositions according to the present invention also cover compositions with a solid content different from 39%, compositions with temperatures different from 20°C and compositions which are in a liquid solution different from an aqueous solution.
  • the 39% solid content, the 20°C temperature and the aqueous solution simply relate to the condition under which the viscosity should be measured.
  • the modification treatment according to the invention may be performed by 5 different means or combination of different means.
  • the modification treatment may be selected from the group consisting of mechanical treatment, chemical treatment, enzymatic treatment, temperature treatment and pressure treatment.
  • said mechanical treatment is provided by beading, milling,
  • said means for making these mechanical treatments may also vary.
  • said beading, milling, comminuting or grinding is performed by a bead mill.
  • the period of performing the modification treatment may vary depending on the specific type of treatment at the desired viscosity to reach.
  • said modification treatment such as mechanical treatment, may be repeated for at least 2 minutes such as at least 5 minutes, such as least 10 minutes, such as at least 20 minutes, such as at least 30 minutes, such as at least
  • the modification treatment such as mechanical treatment is repeated for a period of 2 minutes to 8 hours, such as 2 minutes to 4 hours, such as 2 minutes to 60 minutes, such as 15 minutes to 60 minutes.
  • the time may be adjusted also by e.g. the force applied during
  • the force may also be adjusted by the size of the beads.
  • the optimal size of beads may be determined by determining the size of the particles which are to be 30 exposed to the bead mill.
  • the Particle size ditribution in a sodium silicate composition was determined by using a Malvern Mastersizer 2000 instrument with a Hydro S dispersion unit with demineralised water as dispersant. The measurement was performed by means of laser diffraction and particles in the size interval from 0.02-2000 ⁇ are measured.
  • the sample (unmodified waterglas type 44) was measured twice.
  • the particle size distribution is calculated based on the assumption that the particles are spherical.
  • the Waterglass were found to contain two particle sizes. One size was
  • the optimal bead size is calculated as follows:
  • Max grinding result 0.45 ⁇ .
  • the beads have an average diameter in the range 20- 1300 ⁇ , such as in the range 100-1300 ⁇ , such as in the range 200-1300 ⁇ , such as in the range 300-1300 ⁇ , such as in the range 400-1300 ⁇ , such as in the range 500-1300 ⁇ , such as in the range 20-1000 ⁇ , such as in the range 20-800 ⁇ , such as in the range 20-600 ⁇ , such as in the range 20-400 ⁇ , such as in the range 20-300 ⁇ , such as in the range 20-200 ⁇ , such as in the range 100-700 ⁇ , such as in the range 200-600 ⁇ , such as in the range 300- 500 ⁇ .
  • a glass bead may e.g. made of glass (such as microglass beads) or titanium. Glass beads are commercially available and may be obtained from Sigmund Lindner. Thus, the skilled person may adjust several parameters of e.g. mechanical treatment to obtain a desired viscosity level.
  • the second metal silicate composition has a reduced viscosity relative to the first metal silicate composition
  • the second metal silicate composition has a reduced ratio between the
  • metal silicates In the art of metal silicates, it is generally believed that the viscosity of metal silicates depends on the solid content, the ratio between the metal and the silicate, the density and the temperature.
  • WO2009/087262 describes the problem of high viscosity sodium silicate when impregnating wood.
  • composition comprises an equilibrium of different forms of the metal silicate (textbook by Her; The chemistry if silica, 1979; figure 3.42 and corresponding text). Without being bound by theory it is the hypothesis that the equilibrium is shifted towards ring structures (and away from branched structures) when the composition is treated according to the present invention, such as by mechanical treatment. Thus, since it may be difficult to define the composition by its components the viscosity of the composition may be used as a reliable measure of a very specific feature for such composition and a good indicator for that the components of a composition has been modified.
  • an aspect of the present invention relates to a liquid metal silicate composition obtainable by a process according to the present invention.
  • the viscosity is reduced without changing the
  • the concentration of metal silicate in the composition is the same as the solid content in the first composition.
  • the viscosity is reduced independently of the solid content.
  • the viscosity is reduced without changing the ratio between the metal component and the silicate component.
  • the viscosity is reduced without changing the temperature of the metal silicate in the composition or the overall temperature of the composition.
  • compositions for preserving cellulosic material Use of a composition for preserving cellulosic material
  • Liquid metal silicate compositions according to the present invention may find use in different applications. It is well known in the art that e.g. sodium silicate may improve preservation of cellulosic materials, such as wood. However, it is also known that sodium silicate cannot penetrate into wood. Thus, sodium silicate preservation may only result in surface preservation, which of course is less efficient, e.g. if preserved wood is subsequently cleaved into smaller units or wear which would result in surfaces starts appearing which are not preserved. Thus, in yet an aspect the invention relates to the use of a composition according to the invention for preserving cellulosic material.
  • composition according to the present invention may be part of e.g. a liquid paint formulation.
  • liquid metal silicate composition of the present invention may preferably be applied to a cellulosic material.
  • a preferred embodiment of the present invention relates to a process for providing a cellulosic material comprising liquid metal silicate, the method comprises the steps of:
  • liquid metal silicate composition according to the invention, - optionally diluting or concentrating said liquid metal silicate composition, - positioning said liquid metal silicate composition into and/or onto said cellulosic material, providing a cellulosic material comprising metal silicate.
  • liquid metal silicate compositions according to the present invention show penetration of higher concentrations of metal silicate into the cellulosic material, such as wood, compared to unmodified liquid metal silicate compositions (see also example 2).
  • the provided liquid metal silicate composition has a viscosity of 45 mPa.s or less, measured at 20°C at a solid content of 39% or about 39%, in an aqueous solution.
  • the modification treatment is mechanical treatment.
  • the term "into said cellulosic material” refers to the situation where the metal silicate according to the present invention is introduced more than 1 mm into said cellulosic material, such as more than 2 mm, such as more than 3 mm, such as more than 4 mm, or such as more than 5 mm.
  • the term "onto said cellulosic material” refers to the situation where the metal silicate according to the present invention is introduced at the most 1 mm into said cellulosic material, or such as at the most 0.5 mm. It is to be understood by the mentioned distance, that it relates to the distance from any surface of said cellulosic material, wherein said surface is a surface visible to the human eye.
  • a "surface” is not a microscopic surface present inside e.g. a wood structure, but relates to what would normally be considered the surface of e.g. a standard wood board.
  • modified liquid metal silicate composition (second metal silicate composition) of the present invention were able to penetrate the cellulosic material (the sapwood) and enter into the cellulosic material.
  • the unmodified liquid metal silicate composition (second metal silicate composition) of the present invention were able to penetrate the cellulosic material (the sapwood) and enter into the cellulosic material.
  • composition (a first metal silicate composition) was not able to enter into the cellulosic material but stayed onto the surface of the cellulosic material. See also example 3.
  • the viscosity of the liquid metal silicate composition of the present invention is relatively lower than an unmodified metal silicate composition, there may still be a high solid content.
  • the liquid metal silicate composition according to the invention has a solid content of the metal silicate in the range 0.5% - 80%, such as in the range 0.5% - 70%, such as in the rang, 0.5% - 60%, such as in the range, 0.5% - 50%, such as in the range, 0.5% - 40%, such as in the range, 0.5% - 30%, such as in the range, 0.5% - 20%, such as in the range 0.5% - 10%, such as in the range 0.5% - 5%, such as in the range 0.5% - 3%.
  • the liquid metal silicate composition according to the present invention has a solid content of the metal silicate in the range 5-60%, such as 10-60%, such as 15-60%, such as 20-60%, such as 30- 60%, such as 10-50%, such as 10-40%, such as 10-30%, or such as 10-20% metal silicate. Since this may also depend on the specific type of cellulosic material the user has to consider whether it is appropriate to dilute or concentrate the composition before use.
  • heart wood is denser in structure than sapwood it is more difficult to get the liquid metal silicate composition into heartwood compared to sapwood.
  • sapwood has a more open structure which may allow the metal silicate composition to penetrate more deeply into the structure.
  • Some cellulosic material, such as boards may comprise both heartwood and sapwood and they may not be equally modified with the liquid metal silicate composition.
  • heartwood is much more resistant to e.g. moisture and therefore also microorganisms such difference may not affect the overall preservation of the material.
  • composition according to the invention when used for wood preservation it may be advantageously to have other components added to the composition.
  • the liquid metal silicate composition further comprises one or more coloring agents.
  • the liquid metal silicate composition further comprises one or more stability enhancing agents. Coloring agent may be beneficial if there is a need to change the appearance of the cellulosic material e.g. wood boards.
  • the liquid metal silicate composition further comprises surfactants or lubricants to increase the uptake in cellulosic materials.
  • the invention relates to a cellulosic material obtainable by a process according to the invention.
  • the present example illustrates how the viscosity of different types of sodium silicate composition can be lowered.
  • sodium silicate type 37/40 and sodium silicate type 44 were processed in a bead mill for different periods of time ranging from 0-40 minutes. The viscosity of the compositions was subsequently measured using a Brookfield viscosimeter model LVT-DVII, memorinr. 017141.
  • Unmodified liquid sodium silicate is generally produced by fusing sand and soda ash and may be provided by different suppliers.
  • a sodium silicate type 37/40 and a sodium silicate type 44 were modified as described earlier in the specification. Irrespective of the type of sodium silicate used, it was observed that the viscosity dropped significantly with increasing time of treatment/modification of the specific type of sodium silicate. After approximately 30 minutes it seemed like the In a second experiment the viscosities were measured using a Brookfield viscosimeter at 20°C.
  • the table below shows a comparison of the viscosities of modified and unmodified type 37/40 and a type 44 sodium silicate. The samples were modified for 40 minutes.
  • the lowered viscosity is stable for at least three month when stored at ambient temperature.
  • the present example illustrates how cellulosic materials (exemplified by wood boards) may be preserved using sodium silicate with a lowered viscosity compared to a standard (un-modified) sodium silicate.
  • Wood boards (Pine size from 19x100mm to 50x125mm) were preserved with sodium silicate modified according to the present invention using the following process.
  • Modified (by a bead mill as described above) or un-modified sodium silicate Type 44 were diluted in water to a solid content of approximately 3.9% and 7.8%.
  • This example illustrates how leaching of sodium silicate may be avoided after preservation of the cellulosic material.
  • an after-treatment protocol comprising drying said preserved wood, wherein said drying is performed under reduced pressure, e.g. vacuum, at a temperature in the range 45-85°C.
  • Different ranges of reduced pressure may be applied such as 1-90% vacuum. Similar the temperature may be in the range 45-85°C.
  • the time of drying may depend on the type and size of the cellulosic material, thus the time of drying could be in the range 1-3 weeks.
  • An advantage of this procedure compared to standard heating processes is that due to the vacuum the same effect may be obtained at a lower temperature. This is more cost effective.
  • another important feature is that the cellulosic material is not exposed to high temperatures which may result in e.g. bending of wood materials.
  • Wood boards impregnated with low viscosity modified sodium silicate Wood boards impregnated with low viscosity modified sodium silicate.
  • Wood sapwood of scots pine (Pinus sylvestris) of a length of 1.2 meters and a thickness of 2 cm.
  • Sodium silicate Modified sodium silicate type 44 as described in example 1 heated to 60°C.
  • Wood Sapwood of scots pine (Pinus sylvestris) of a length of 0.5 m, width of 0.1 m, and a height of 0.025 m. Volume 0.00125 m 3
  • the boards were sealed at the ends before impregnation to avoid uptake through the ends.
  • Sodium silicate Modified sodium silicate type 44 as described in example 1 heated to 60°C.
  • Figure 1 shows two boards impregnated with sodium silicate. Top: modified low viscosity sodium silicate. Bottom : Un-modified sodium silicate according to the present invention. Dark coloring indicate impregnated parts of the wood.
  • low viscosity modified sodium silicate can penetrate into the center of a standard board. Importantly it can also be seen that un-modified sodium silicate is unable to penetrate the wood and therefore stays at the surface of the wood.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical And Physical Treatments For Wood And The Like (AREA)

Abstract

La présente invention concerne une matière cellulosique comprenant un silicate de métal comprenant un silicate de métal détectable à plus d'1 mm de toute surface de ladite matière et/ou comprenant au moins 50 kg de silicate de métal/m3 de matière cellulosique ; ladite matière cellulosique n'ayant pas été prétraitée avec un champignon de bleuissement et/ou ladite matière cellulosique ne comprenant pas de champignon de bleuissement, viable ou non, ou de traceurs de celui-ci.
PCT/DK2012/050286 2011-08-02 2012-08-02 Matière cellulosique comprenant un silicate de métal WO2013017135A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
PCT/DK2013/050258 WO2014019590A1 (fr) 2012-08-02 2013-08-02 Composition comprenant des silicates de métal dotés de dimensions des particules réduites
US14/418,637 US20150183888A1 (en) 2012-08-02 2013-08-02 Composition comprising metal silicates with reduced particles sizes
EP13752576.2A EP2879848A1 (fr) 2012-08-02 2013-08-02 Composition comprenant des silicates de métal dotés de dimensions des particules réduites

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DKPA201170424 2011-08-02
DKPA201170424 2011-08-02

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CN107356543A (zh) * 2017-05-10 2017-11-17 华南理工大学 一种在线光谱法检测高吸水性树脂吸水速率的方法
EP4039430A1 (fr) * 2021-02-09 2022-08-10 Leko Labs SA Procédé de fabrication d'un composite bois-polymère

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Publication number Priority date Publication date Assignee Title
CN107356543A (zh) * 2017-05-10 2017-11-17 华南理工大学 一种在线光谱法检测高吸水性树脂吸水速率的方法
CN107356543B (zh) * 2017-05-10 2020-02-18 华南理工大学 一种在线光谱法检测高吸水性树脂吸水速率的方法
EP4039430A1 (fr) * 2021-02-09 2022-08-10 Leko Labs SA Procédé de fabrication d'un composite bois-polymère
WO2022171613A1 (fr) * 2021-02-09 2022-08-18 Leko Labs Sa Procédé de fabrication d'un composite bois-polymère

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