DE3005406A1 - METHOD AND MEANS FOR TREATING WOOD - Google Patents

Description

description

The invention relates to the treatment of wood in order to improve its properties, in particular it relates to that Impregnation of wood with a resin and, if necessary, with various additives such as wood preservatives and fire retardants or flame retardants (hereinafter generally referred to as "flame retardants").

It is known that wood expands and contracts depending on the degree of swelling of its cell walls. The cell walls of wood have varying degrees of swelling depending on the specific solvent or solvent vapor to which it is exposed is, and depending on its affinity for this solvent or solvent vapor. This is how you get one high degree of swelling if wood is exposed to water or steam while its cell walls are drained, which leads to leads to shrinkage if one uses less polar solvents or mixtures of solvents, such as an ethanol / xylene mixture, suspends.

In addition, the cell wall of wood, which consists mainly of cellular chains, exhibits a maximum when it is swollen Porosity, i.e. the free space between the respective cellular chains is large, and if they are not is swollen, the porosity is very small. Hence, the size and amount of the molecules that are inside the cell walls depend on can be deposited or separated by wood, depending on the degree of swelling of the cell walls.

The aforementioned property of wood is used in many ways

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Wisely exploited to give it specific properties. For example, water-soluble polyglycols, such as, for example, polyethylene glycol with a molecular weight of about 3000 to about 6000, can be introduced into the cell walls of wood in the wet or swollen state (cf. AJ Stam, "New and Better Ways to Dimensionally Stabilize Wood" in "Forest." Products Journal ", 9 (1959): 3,107-110, and Harry C. Le si ie,""Man Society Technology, A Journal of Industrial Arts Education" 33 (1): September 13-16 / October 1973) . These polyglycols have a low vapor pressure and, unlike water, evaporate very slowly. Therefore, the above treatment is very effective in preventing wood from cracking. Such a treatment is often used to treat wood engravings, wooden statues and the like in order to give these pieces of wood a long life even if they are kept in a dry atmosphere. However, polyglycols remain water-soluble and are leached out when wood treated with them is exposed to humid conditions. The applicability of this treatment is therefore very limited. Using roughly the same concept, water-soluble phenolic and urea resins of low molecular weight are used to treat wood (see U.S. Patents 3,968,276, 3,519,476 and 3,493,417). In order to fix these resins within the cell walls of the wood, the phenolic resin must be hardened or crosslinked after the heat treatment in order to make it insoluble in water. Very often a combination of heat and pressure is used to further compact the wood. Such treatment requires, even if it is effective, the use of special equipment and it is therefore only ⁺ '"PEG of the Woodworker's Heart" in

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the industrial production of special objects applied, where resistance to water or chemicals or structural strength or a combination of which is required.

Many other polymers have also been used to impregnate wood * Some of them include the Use of acrylic type monomers (U.S. Patent 3,663,261), polyisocyanate (US Pat. No. 3,539,386) and dibromopropyl glycidyl ether (US Pat. No. 3,483,021). at All of these treatments require a secondary treatment of the wood after impregnation in order to remove the monomers polymerize in situ to fix them in the wood. The most commonly used secondary treatment is darjh to heat the impregnated wood, although in the case of vinyl-type monomers, such as acrylic monomers, also one Gamma irradiation can be applied. The secondary treatment after impregnation is expensive and cumbersome. As a result, none of these methods have gained wide acceptance in the industry.

Even if the cell walls of the wood are in a wet or in a swollen state, only relatively small molecules can penetrate the cell walls of the wood. the The size of the molecule that penetrates the cell walls of the wood depends on the degree of swelling and the type of wood away. Polymers with large molecules do not penetrate into a swollen wood cell wall either. For example Polyvinyl acetate and. Polyacrylate emulsions for years Manufacture of adhesives and protective coatings for wood used. Unlike condensation polymers, such as that

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phenolic resin mentioned above, these emulsions are produced by free radical or chain polymerization and they do not contain appreciable amounts of low molecular weight components (see F. W. Billmeyer Jr., "Text Book of Polymer Science", Interscience Publishers, 1966). As a result, the wood cell walls swell when that Wood is treated with these emulsions, as a result of the presence of water on it, but the polymer molecules are too big to penetrate the swollen wooden cell wall. The wood is therefore given a protective coating, his however, other properties, such as resistance to cracking, are not affected. It is therefore it is not possible to use a water-dispersed polymer having a large molecule to achieve the objects of the invention to reach.

Although low molecular weight vinyl resins such as acrylic resins are already known to be useful for the treatment of wood cell walls, for the resistance to cracking, the dimensional stability and others Up to now, however, it was not known to improve properties. Such resins have been proposed, for example for use in polishing agents as a leveling aid1.

Alkyd resins are condensation polymers, and they contain a significant amount of components with a low Molecular weight (see "Text Book of Polymer Science", supra). In addition, alkyd resins can be crosslinked and cured , i.e. they become solvent-resistant and

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partially infusible if they are allowed to react with air. So far they were only soluble in organic solvents Alkyd resins standard commercial products. The organic solvents in these alkyd resins do not cause any swelling the wooden cell walls. Many of them even cause the wood cell walls to shrink through displacement of water and reduce the porosity of the wood.

In the past decade, alkyd resins have been used in water or in a mixture of water and a polar solvent are soluble, to a large extent in industrial finishes, such as coatings for washing machines, refrigerators, Automobiles and the like., Used. It was not previously known, however, that it was also the basis for a Wood treatment represent to this so highly_desired To impart properties, such as reduced cracking, improved dimensional stability and practically permanent fire resistance or flame retardancy and good preservation without the need for secondary heating or gamma irradiation treatment after impregnation is required. It is enough to simply expose them to air to cross-link them to form a polymer in situ to build. Since they are in water and contain a very large amount of small but reactive molecules, they also penetrate the wooden cell walls excellently.

The invention relates to a method for treating wood in order to improve its properties, thereby is characterized in that the wood to be treated with a water-dilutable resin in a water-miscible

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Solvent and water are brought into contact in an amount sufficient to keep the resin in the cell walls of the wood fibers to separate out (to be deposited), whereby the resin contains molecules of one size, which in the free cavities can enter the cell walls, and the resin in the cell walls is converted into a water-insoluble form will. With this treatment one obtains wood with an improved dimensional stability and with an improved one Resistance to cracking when exposed to water. Further improvements to the wood properties can be achieved by adding additives such as preservatives (wood preservatives) or fire-resistant or flame retardants (flame retardants) separates or deposits in the cell walls of the wood and fixes the additives therein with the insolubilized resin.

In a preferred embodiment of the invention Specific chemical mixtures are permanently deposited (deposited) within the cell walls of wood fibers, whereby the combination of chemicals to be deposited in water or in combinations of water and a water-miscible one Solvent have been made soluble so as to swell the wood cell wall and maximize it To achieve penetration of the chemicals into the wall itself. The chemicals are selected so that at least one of the components of the mixture consists of molecules of a small size, which in the presence of the solvent in the free cavities in the cell walls can penetrate and the ambient conditions either alone or assisted due to the presence of other chemicals, which can act as catalysts, in a water-insoluble

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borrowed form can be converted, taking them at the same time include other water soluble chemicals that may be present in the mixture, reducing the tendency of the Total mixture, leached out during the subsequent treatment of the wood with water or with water-containing solutions to be eliminated or greatly diminished.

In the chemical used according to the invention, which is in a water-insoluble form can be converted, it can be a water-dilutable alkyd resin or a modified, act alkyd resin that can be diluted with water. Examples of such alkyd resins are dilutable with water long, medium or short oil alkyd resins currently used by a number of different manufacturers are commercially available and in the industrial coating industry are known. Modified alkyd resins, such as urethane modified alkyd resins, are also commercially available and known to those skilled in the art. These alkyd resins or modified alkyd resins are generally in or in water Mixtures of water and a polar solvent soluble in almost neutral or weakly alkaline solutions, Examples of suitable polar solvents are butanol or higher alcohols, ketones, butyl cellosolve, butyl carbitol, Propasol and N-methylpyrrolidone.

As is known, alkyd resins are made by combining synthetic dibasic acids such as phthalic anhydride, Isophthalic anhydride, trimellitic acid, with synthetic or natural fatty oils, i.e. glycerides of fatty acids. The fatty acids or their glycerides that generally contain mixtures of

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Fatty acids with varying chain lengths and varying degrees of unsaturation in the chain.

Alkyd resins can additionally be modified by combining them with different glycols. Examples for glycols that are commonly used are pentaerythritol diethylene glycol. More drastic changes in alkyd resin properties can be achieved by crosslinking the same by adding isocyanates such as toluene diisocyanate. The latter alkyd resins are commonly referred to as urethane modified alkyd resins. Alkyd resins modified with urethane dry out to be much harder surface coatings (finishes) than alkyd resins, which have not been modified in this way. Other examples of modified alkyd resins include Modification by reacting them with natural resins, such as rosin, or with other synthetic resins, such as phenolic resins, Amino resins, silicone resins, or by reacting them with imides, styrene and the like.

The final molecular weight or the degree of polymerization of the alkyd resins is controlled by adding controlled Amounts of an excess of one of the reactants - the fatty acids or glycols. As a result, the finished contain Alkyd resins generally contain minor amounts of unreacted hydroxyl or acid groups, or both. Alkyd resins made using relatively low Synthetic polybasic acid to fatty acid ratios have been established are called long oil alkyd resins denotes those who are using a

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very high ratios are known as short oil alkyd resins and those under Using a medium ratio are referred to as medium oil alkyd resins.

The alkyd resins of the above type are in both aromatic and aliphatic hydrocarbon solvents soluble and insoluble in most polar solvents such as water, methanol and butanol. before Recently, alkyd resins have been reacted with various chemicals to increase their solubility in polar solvents to enhance. This can be achieved by incorporating more polar groups into the alkyd structure. So For example, an alkyd resin can be made using an excess of acid, the end product being has an acid number that is within the range of from about 10 to about 100, preferably from about 20 to about 60. The acid groups are then determined using an amine or ammonia or a combination partially or completely neutralized by amines and ammonia. The products made in this way are then in polar solvents such as methanol, butanol, carbitol, butylcellosolve (ethylene glycol monobutyl ether) and Mixing these solvents with water, soluble. To achieve complete solubility, you may need Mixtures of solvents of the above type can be used. For example, some these alkyd resins have better solubility in higher-boiling solvents, such as butyl carbitol (diethylene glycol monobutyl ether) or butylcellosolve, on and in addition can

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adding these solvents will increase the amount of water that can be used as part of the solvent system. The alkyd resins which can be used according to the invention are are these alkyd resins that have been modified to dissolve them in polar solvents, and they will referred to here as water-dilutable alkyd resins.

In addition to simple alkyd resins, oil alkyd resins can also be used a short, medium or long chain, which by reacting the same with isocyanates, acrylic! compounds or other suitable chemicals commonly used to modify alkyd resins can be used in the practice of the invention. These modifications are the same such as those used in conjunction with aikyd resins based on an organic solvent, which have been further modified with neutralizable acid groups in order to make them soluble in polar solvents do.

It should be noted that the present invention is by no means limited to the above types of modified Aikyd resins is limited. Any water dilutable can be used in the practice of the invention polymeric system used in polar solvents or mixtures of polar solvents or mixtures of a polar solvent and water is soluble and, for example, by curing (crosslinking) by exposure to air or by evaporation of water or by volatilization of a water-soluble making amine component under temperature and pressure

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Environmental conditions can be converted into a water-insoluble stage. To achieve the best results each resin that is selected should contain at least 5% by weight molecules having a molecular weight less than about 1000, preferably 10% by weight of molecules with a molecular weight of less than about 1000. This will the entry into the free spaces of the wooden cell wall is encouraged. The largeran molecules that are too large to fit into the Being able to enter free spaces of the wooden cell wall forms a protective and decorative layer on the wooden surface.

Although all polymeric systems which can be diluted with water, as indicated above, are in accordance with the invention are generally useful, it should be noted that some resins may be more suitable for a particular application can than others. For example, the stability of the resin-solvent systems and in some systems differs resin precipitation can occur faster than in others. It was found that the choice of resin is more critical for stability in more dilute resin solutions containing less than about 20 weight percent resin. Several resins can be tried in such solutions in order to select one with optimal properties. Example 3, described below, illustrates a resin-solvent system with relative long-term stability at low resin concentrations.

Alkyd resins that can be thinned with water react like alkyd resins that can be thinned with oil or an organic solvent or modified alkyd resins with the oxygen

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in the air and they crosslink to form a water-insoluble product. The networking speed The rate can be increased by adding small amounts, generally 0.05 to 1.0% by weight, of catalysts such as e.g. Desiccants, can be increased considerably. examples for Desiccants that can be used according to the invention, are calcium, cobalt, manganese and zirconium naphthenates or chelate salts of calcium, cobalt, manganese or zirconium.

It has surprisingly been found that the above-mentioned, water-dilutable alkyd resin solutions, when applied to wood are applied, penetrate into the wood cell wall and are insoluble in water when exposed to air will. They can therefore be used to stabilize the wood cell walls, greatly improving them Dimensional stability or a reduced tendency to expand and contract with changes in humidity, to lend.

It has also surprisingly been found that other chemicals which are normally water soluble or in the above mentioned Alkyd resin solutions are soluble when in contact are used with these alkyd resin or modified alkyd resin solutions, also penetrate the HolzzeE walls and are fixed in the wood during the subsequent air curing of the alkyd resin or modified alkyd resin and are practically not leachable by water.

This cannot only be applied to make the wood dimensionally stable to make but it can also applied

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to treat wood with a string of chemicals that give it durability and other special properties. In this way, normally water-soluble fire retardant or flame retardant chemicals can be used to make treated wood permanent, non-water leachable fire retardant or fire retardant. to impart flame retardant properties. In a corresponding manner, water-soluble wood preservatives of both organic and inorganic nature can be incorporated into wood, and after the alkyd resin or modified alkyd resin has cured, they are no longer leachable so that the wood is able to retain these compounds even under wet and damp conditions of use .

The present invention can be used in a variety of ways. For example, if you wish is to make wood dimensionally stable and resistant to cracking, a simple treatment with a Solution of an alkyd resin that can be diluted with water and that contains suitable drying agents, resulting in drying connected to the air, suffice. The amount of material deposited or deposited in the wood cell walls is proportional to the concentration of the material in the treatment solution. This applies to both the binder polymer as well as for the other components, such as the wood preservatives or fire-retardant or flame-retardant Medium (fire retardant).

The polymer binder used can be used in a concentration

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tion of about 70 wt .-% or of only about 5 wt .-% are present. In general, mixtures of about 5 wt.% To about 30% by weight is preferred, since above this concentration range the viscosity of the solution is very high. Very viscous Solutions take a long time to move into the wood. The viscosity can be reduced somewhat by heating the solution will. From a purely practical standpoint, however, it is more convenient to use room temperature and use lower concentration ranges. Although concentrations of about 5 wt .-% resin binder already one significant improvement in terms of dimensional stability of treated wood and with regard to the fixation of other additives in it should result in a concentration at least about 8% by weight resin are used, if it is to be essentially prevented that the additives are leached out by water.

The amount of wood preservative or mixtures of wood preservatives used depends in turn on the desired level of protection. Pentachlorophenol can, for example, in concentration ranges from about 0.5 to about 6% by weight, preferably from about 2 to about 5 weight percent. On the other hand, tributyltin oxide adducts are generally used used in concentration ranges from about 0.1 to about 0.5% by weight. Fire retardants can be used in a corresponding manner or mixtures of fire retardants in concentration ranges from about 2 to about 15% by weight are used which in turn depends on the level of protection required. Other wood treatment chemicals that can be used are copper 8-quinolinolate and copper ammonium borate.

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The wood can be treated sequentially or simultaneously with preservatives, fire retardants and resin binders will. If the wood is first coated with a fire retardant or wood preservative and then with the binder of the System according to the invention is treated, can be higher Degrees of protection are achieved than are possible with simultaneous treatment. For example, a Fire retardants, such as borax, are only compatible with the binder system according to the invention up to about 4% by weight (compatible) and to achieve the desired level of fire resistance a larger amount must be in the Wood can be deposited (deposited). In such circumstances, the wood can first contain 10 to 15 wt% borax in water and then with the binder of the invention System are treated to fix the higher borax concentration in the cell walls.

The resin binder and other wood treatment chemicals may be brought into contact with the wood by any suitable method. All are applicable conventional methods such as brushing, spraying, dipping or by putting the wood under Vacuum sets what the treatment with the treatment solution under pressure at ambient temperature or higher Temperature follows, depending on the type of wood used and the desired degree of penetration.

If desired, in the formulations or preparations conventional pigments, dyes, thickeners, leveling agents and extenders both organic and

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may also be of an inorganic nature.

The invention is illustrated in more detail by the following examples, but without being limited to it.

example 1

The improvement in wood properties achieved by the present invention is reflected in the durability of the Wood against dimensional changes when changing the

Moisture content and dimensional changes

3
of the wood itself. For maple samples of about 1.5 cm, which are made with resin solutions with a concentration of 20, 40 and
60% by weight impregnated and left in the air for two weeks
have been dried, the following % dimensional changes were found in the saturated moisture content and in the dry state.

Resin in the
Solution (wt .-%) Tangential
V / o / Radial
(Ί ^ ^+>
V / o / 0 112.18 105.46 20th 110.25 103.86 40 109.24 103.44 60 104.94 101.83 Dimension in the Saturation χ 100 Dimension in the Oven drying

The above results were obtained when the

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Place wood samples overnight in the resin solutions given in the table below. After the two week air drying period they were re-immersed in water overnight. Oven drying was carried out at (.50 C to weight inconsistency; performed and it usually lasted about 3 hours.

Ingredients 60% by weight 40% by weight 20% by weight

dilutable with water

Medium oil alkyd resin, 627.0 412.0 200.0

80% in butyl cellosolve

Ammonium hydroxide (28 / O) 36.0 24.0 12.0 Butyl cellosolve 34.6 77.6 120.0 water 138.4 310.4 480.0 6% cobalt naphthenate ⁺⁾ 4.0 2.7 1.3 18% Zr-naphthenate ^+; 2.0 1.3 0.7 Active 8+ ⁾ 2.8 1.9 0.9 BYK 301 ⁺⁺⁾ 6.0 4.0 2.0 all in all 836.0 824.0 812.0

⁺ ^ 6% Co-naphthenate, 18% Zr-naphthenate and Aktiv-8 are drying agents

^{++ /} BYK 301 is a wetting agent

From the above results it can be seen that impregnation of wood with the solution is a great improvement the dimensional stability and that the dimensional stability imparted in the tangential direction was bigger. It is also essential that treatment be given too

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an equalization of the changes in direction both in tangential as well as in the radial direction. The improvement in dimensional stability also shows that the Polymers actually penetrated the cell wall.

Similar results were obtained when treating Lindmholz-jZuckerhutfichtai-jPelbpappel samples with the above Solutions.

During this investigation it was also found that the wood did not return to its original dimensions after treatment with the resin solution and the subsequent one-week hardening in air. The% dimensional changes in this treatment for maple are given below:

Resin con ζ en t ra 11on
(Wt%) Tangential Radial Sample (oven dry) 45 0 0 0 15th 20th 103.4 101, 64 40 103.86 102, X 60 105.81 102, Length of treated

Length of the untreated sample (oven dry)

This is further evidence that the polymer actually penetrated the wood cell walls.

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Example 2

The treatment of wood according to the invention gives it not only dimensional stability but also greatly improved resistance to cracking. This has been demonstrated on the basis of three equivalent samples' staining areas.

Sample 1 was only dried in the oven and was relatively free of cracks *

Sample 2 was oven dried, saturated with water by immersion for about 20 minutes, and then oven dried. Numerous cracks were visible.

Sample 3 was oven dried and then immersed in the polymer system given in the table below. Only a few small cracks were visible after oven drying.

Components parts by weight

Medium oil dilutable with water- 248.70 Alkyd resin, SO% in butyl cellosolve

Ammonium hydroxide (28%) 15.00

Butyl cellosolve 59.51

Water 493.93

Tinuvin 328+ ⁾ 4.46

6% cobalt naphthenate 1.24

18% Zr naphthenate 0.62

Active-8 1.36

BYK 301 2.60

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'Tinuvin 328 is a UV absorber

Example 3

It has already been shown earlier that wood preservatives and fire-retardant or flame-retardant agents (fire retardants), which are leached out of wood when exposed to water, for example by rain, according to the invention essentially fixed in the wood and can no longer be made accessible.

Pentachlorophenol is a common wood preservative * For its job, pentachlorophenol is generally dissolved in aromatic and aliphatic hydrocarbons. Wood blocks that have been treated with pentachlorophenol lose the wood preservative when they are leached with water at a very high rate.

3
A 1 cm block of wood was treated with 5% by weight of pentachlorophenol and examined for its chlorine content before and after leaching with water (1 month) using an energy dispersive X-ray analysis (EDXA). The absence of chlorine in the leached sample clearly indicated that most of the pentachlorophenol had been leached. Another 1 cm block of wood was treated with a solution of 5% by weight of pentachlorophenol and 14% by weight of water-dilutable alkyd resin. The block was air dried for 30 days. Again was under

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Application of the EDXA. before and after leaching with water (1 month) determines its chlorine content. The result clearly showed that very little chlorine was lost were - the polymer had fixed the pentachlorophenol within the wood.

The same procedure can be used to add other chemicals such as fire retardants to wood and make them non-leachable.

⁺ 'The treatment solution was prepared from a combination of the mixtures A and B given in the table below.

Mixture A
Pentachlorophenol
Butyl cellosolve
Ammonia (28 %)

Mixture B

Aroion 385+ ⁾ 955

Ammonia (28%) 22

Butyl Cellosolve 64 Cobalt Hydrocure 6.5

Activ-8 4.0

Mixture A 1190

it was mixed for 15 minutes and it was added:

Water 2700

Adjustment of the pH value with ammonia (28%) to 8.5

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Alkyd resin diluted with water, sold by from Ashland Chemical Company

Example 4

This example shows that, similar to the wood preservative of Example 3, there is also a fire retardant inside the wood cell walls can be deposited (deposited) and fixed against leaching with water by the resin.

The procedure described in Example 2 was repeated, this time using 42 g of the binder mixture of Example 2 (5%) sodium borate was added. The wood blocks used were 5 cm by 10 cm by 1/2 cn. After treatment the block was air dried at room temperature for two weeks. Then he was at his broadside incised up to half. One of the halves was repeatedly washed with water and allowed to air dry. The water-washed and non-washed parts of the block became a lighted match that was in a Distance of 10 cm from the end grain side of the block was exposed. Both blocks started after 8 minutes to char. In the case of an untreated block, the charring started afterwards under identical conditions 4 minutes.

The above discussion and experiments are primarily illustrative of the present invention based on the use of water-dilutable alkyd resins

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Zen. As indicated above, however, the present invention can be used with any water-dilutable polymer System can be carried out in polar solvents or mixtures of polar solvents with water is soluble and then convertible to a water-insoluble stage. In this regard, it has been found that Film-forming resins which can be diluted with water and prepared from vinyl monomers are advantageous for the use according to the invention Have properties. These water-dilutable resins, derived from vinyl monomers, are made by Water evaporation in the g and film formation and / or by volatilization ammonia or an amine that has reacted with acid groups in the resin to a form insoluble in water converted.

The water-thinnable resins based on vinyl monomers are advantageous in that they contain much less organic polar solvent can be formulated as the water-thinnable alkyd resins. Indeed it is Certain types of these vinyl resins do not require any organic solvent at all and they only will formulated with water as the solvent as indicated in U.S. Patent Application No. ^ A02A.

In the present case, small amounts of a water-miscible organic solvent can be used, to achieve a vinyl resin that forms a film under ambient conditions. The use of only small amounts of the organic solvent (generally less than about 10% by weight, preferably less than 5% by weight,

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based on the weight of the preparation) offers both environmental and economic advantages Advantages. The functional advantages are very important.

In this context it should be noted that the organic cosolvents used to make the alkyd polymer mixture dilutable with water, too good solvents for some of the dark colored chemicals that are naturally found in wood. Therefore, by applying these solutions to the wood, these dark colored compounds appear on the surface brought, the wood becomes dark and its natural beauty is impaired. They also run with water miscible organic solvents cause difficulties with certain types of water-soluble chemicals, such as wood preservatives and fire retardants that are added to the formulation for permanent separation in the wood that has been treated with the formulation (preparation). When adding certain of these Connections to a formulation (preparation) that contains larger amounts of organic solvent separates The mixture is divided into two layers - a resin-cosolvent layer and a water-wood preservative and / or fire retardant layer. This phenomenon closes the use of most water soluble compounds to formulate a uniform wood treatment solution and the larger amounts of organic solvent containing systems are therefore only useful when used in conjunction with chemicals that contain one have fairly good solubility in the mixture, e.g.

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Pentachlorophenol or fire retardants that are soluble in polar solvents. Such connections are expensive, compared to water soluble compounds, and often not as effective when used in appropriate amounts. Through the use of resins made from vinyl monomers, which allows the use of a relatively allow small amounts of organic cosolvents, the above-mentioned problems are avoided Systems exist which require the use of larger amounts of organic cosolvents.

Polymers made from vinyl monomers, such as acrylic polymers, both copolymers and homopolymers, are generally prepared by reactions resulting in a proportionate lead to narrow molecular weight distribution. As with the alkyd resins, the selected resin should be based on Vinyl based at least 5% by weight of the resin molecules have a molecular weight less than about 1000, preferably at least about 10% by weight of the resin molecules have a molecular weight i have about 1000 within. In a preferred embodiment it is desirable to have sufficiently larger molecules available in the formulation, which cannot penetrate the wood cell wall and therefore a protective and decorative outer surface coating form. For this purpose, the preferred formulations (preparations) are those that are usually two different vinyl polymers combine, one with the small molecules for penetration into the wood, and the other with relatively larger molecules for film formation on the surface of the wood. The larger molecules generally have a molecular weight of about

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20,000 to about 200,000, with a typical formulation (preparation) being one in which 95% of the molecules have a molecular weight within the range of 90,000 to 110,000.

It has been found that the iced emulsions that by Emulsion polymerization of vinyl containing monomers can be used to formulate the treating solution. Examples of monomers that contain a vinyl group are vinyl acetate, methyl methacrylate, Ethyl ethacrylate, acrylamide, acrylonitrile, styrene, isoprene and maleic anhydride. These monomers can be polymerized with themselves to form homopolymers. Preferably, however, one is carefully selected mixture of monomers is used to achieve certain properties, such as the minimum film-forming temperature, the hardness of the dried film and the like. To control. The polymerization is generally in the absence of oxygen using a free radical initiator such as a peroxide, wherein the monomer or the monomer mixture is suspended in water, carried out with stirring and the temperature becomes so adjusted so that it is above the temperature which is necessary for the decomposition of the initiator.

Many commercially available acrylic emulsions contain organic ones Cosolvents that serve as thickeners and / or coalescing agents. If these water-soluble wood preservatives or leverschutzmittel are added, a flocculation of the emulsion or one or more of the

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Additives occur. Examples of emulsions which have been found suitable are given below. It however, other emulsions can also be used which are film formers at or below room temperature and are stable in the presence of the additives.

The polymers with a low molecular weight, whether they are in the form of an emulsion or in Be in the form of clear solutions, synthesized using the polymerization reaction described above, this time, however, a suitable chain transfer component is added to the reaction mixture. Emulsion polymers with a large or small molecular weight, which have been prepared using an acid, such as acrylic acid or methacrylic acid, or a mixture of such acids, as part of the monomer mixture, tend to Form clear solutions when amines or ammonia are added to bring their pH to alkaline Range, generally above 8 or 8.5. Although they are soluble in this form, they lose When used as a binder or film former, they use the ammonia or the volatile amine (if a volatile amine used to adjust the pH) by evaporation and they become insoluble in water.

When a mixture of a polymer with a high molecular weight and a polymer having a low molecular weight is used, it co-permeates Water and the additives into the wood cell walls and when the water evaporates it is deposited in it (separated

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stores). The high molecular weight fraction is added to form a film on the outer surface, protecting it from the elements and also giving it an aesthetic look. Through training These components that form a surface film can also be mixed with pigments and the treatment solution To add dyes, so that one. a wood treatment and wood coating or wood staining system in the form of a single mixture. The weight ratio between the The high molecular weight resin and the low molecular weight resin are generally 95: 5 to 50:50, preferably about 90:10 to 70:30.

When such pigmented systems are used, the pigments also serve as UV light absorbers. It is known that UV light breaks down wood. Therefore, the working life of the wood is further improved by incorporating the pigment. at clear coatings, the same goal can be achieved by adding UV absorbers. Typical examples of UV absorbers are given in the examples described above.

The examples described below illustrate typical formulations or preparations in which resins are used which have been made from vinyl monomers and which can be formulated with a relatively small amount of an organic polar cosolvent. In the following Example 5, both the resin having the large molecular weight and the resin having the small molecular weight Molecular weight a variety of acid groups associated with

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Ammonium hydroxide can be neutralized. As a result, it receives a white, transparent solution which is very readily soluble in water. Example 8 explains that it is possible to Formulation (preparation) add inorganic fire retardants and wood protection salts without phase separation occurs because of the relatively low concentration of organic polar cosolvent.

Example 5

Rhoplex B-505 " ⁰ 45.00

Acrysol 527 ^++; 4.44

Ammonium hydroxide (28%) ⁺⁺⁺⁾ 1.00

Water 46.56

Methyl carbitol 3.00

a total of 100.00

Rhoplex 505 is a high molecular weight acrylic copolymer made by Rohm & Haas Company, 40% n.a.

Acrysol 525 is a low molecular weight acrylic resin manufactured by Rohm & Haas Company, 45% n.a.

Ammonium hydroxide is used to adjust the pH value and to achieve clarification.

The total solids content of the above formulation (composition) is 20%. The ratio of B-505 to Acrysol 527 on a solids basis is 9.0: 1.0.

03 0040/061 p

Example 6

Synthemul 40-45O ⁺³ 32.65

Acrysol 527 8.88

Ammonium hydroxide (28 %) 2.00

Water 52.47

Butyl carbitol 4.00

a total of 100.00

⁺ 'Synthemul 40-450 is a polyvinyl acetate / acrylic copolymer emulsion manufactured by Reichhold Chemicals Inc., 49 % nv

Total amount of resin solids = 20%
S-40-450 / AG 527 ratio = 80:20

Example 7

E-1630, 45 % na ⁺⁾ 40.00

Acrysol 527 4.44

Water 52.06

Methyl carbitol 3.50

a total of 100.00

E-1630 is an experimental acrylic emulsion made by Rohm & Haas Company, nv = 45 %

E-1630 / AC-527 ratio = 90:10
Total Resin Solids: 20 %

Example 8

E-1630 40.00

Acrysol 527 4.44

Ö3004Q / Q $ 1S

Fire retardants 10.00

Ny late-10 ⁺ " ¹⁰ 2.00

Water 40.56

Methyl carbitol 3.00

a total of 100.00

Fire retardant made by completely neutralizing dimethylamine with phosphoric acid

⁺⁺ Nylate-10 is a wood preservative manufactured by Seymore Chemicals Co., its active ingredient is copper-8-quinolinolate

Example 9

The formulation (preparation) of Example 8 was based on two 4 "χ 8" blocks yellow cedar applied. The wood was immersed in the preparation for 15 minutes and then on the overnight Allowed air to dry at room temperature. One of the blocks was then under running tap water for 6 hours washed long and dried again overnight at room temperature. The blocks were then subjected to a flame a small blowtorch held 6 inches from its surface. Neither of the two blocks maintained the flame after the blowtorch was removed. After a period of three minutes however, local charring was visible. In a control block of wood that has not been treated at all If exposed to the fire, the wood caught fire and the fire burned within a minute

Ö30040 / QS15

continued after the blowtorch was removed. This experiment shows that the fire retardant (flame retardant Medium) was effective in reducing flame spread and making it non-leachable although it was originally a water-soluble compound.

Example 10

An approximately 1.5 "3" x 4 "(3.8 cm 7.6 cm 10.2) large block of summer oak was immersed in the preparation of Example 8 for 12 hours and for 24 hours air dried. A block of the same size was used as an internal control. The treated block and the control block was then immersed in water for two hours and dried in an oven at 121 C (250 F). When examining these dried blocks, it was found that the untreated block along the radiation cells had cracked while the treated block showed no cracking. This experiment shows that the preparation of Example 8 had effectively stabilized the wood.

The entire experiment was repeated, this time the Acrysol 527 being omitted from the preparation of Example 8 became. In this case it was found that in both the control block and the treated block at Oven drying cracks appeared. This experiment shows that the high molecular weight acrylic polymer alone does Wood not effectively stabilized.

0300AO / 061S

Claims (35)

DIPL.-ING. R. SPLANEMANN dipl.-chem. dr. B. REITZNER REINS. REPRESENTATIVES AT THE EPO 'PROFESSIONAL REPRESENTATIVES BEFORE EPO ■ MANDATAIRES AQREES PRES LOEB Envirosol Systems International Ltd. 73 Orinda Way Orinda / CaI./ USA • ooo Munich 2 February 13, 1980 Tal 13 Telephone (089) 226207/224209 Telegrams: Inventius Munich Telex: 528418 intuid Un.er.Ak,.: 1934-1-10.849 Your reference: Method and means for treating wood Patent claims 1. Method of treating wood to improve its properties to improve, characterized in that the wood to be treated with a dilutable with water Resin in a water-miscible solvent in an amount sufficient to contain an effective amount of the resin to deposit the cell walls of the wood, brought into contact wherein the resin contains molecules of a size that in the presence of the solvent in the free voids in the Cell walls can enter, and that the resin in the cell walls under ambient conditions to a water-insoluble one Shape is transformed. 2. The method according to claim 1, characterized in that a water-containing solvent is used. '- 3. The method according to claim 1 or 2, characterized in that a solvent is used which did water Contains miscible organic liquid. 030iH0 / O61 & 4. The method according to any one of claims 1 to 3, characterized in that that an alkyd resin is used as the resin, which is curable or crosslinkable under the action of air, whereby it becomes insoluble in water. 5. The method according to any one of claims 1 to 3, characterized in, that a resin made from a vinyl monomer is used. 6. The method according to claim 5, characterized in that a resin is used which is made from an acrylic monomer became. 7. The method according to any one of claims 1 to 6, characterized in that that a resin is used which contains or consists of a film-forming emulsion, which by evaporation of the solvent has been made insoluble in water. 8. The method according to any one of claims 1 to 7, characterized in that that a resin is used which contains acid groups neutralized with an amine or ammonia to to make it water soluble and that the amine or ammonia is volatilized to make the resin insoluble in water. 9. The method according to any one of claims 1 to 8, characterized in that that a resin is used which contains at least about 5% by weight of molecules with a molecular weight of less than about 1000 contains. 10. The method according to claim 9, characterized in that 830040 / OS1S a resin is used that has at least about 10% by weight molecules having a molecular weight less than about 1000 contains. 11. The method according to claim 10, characterized in that a resin is used which has a considerable proportion contains larger molecules that cannot enter the free cavities in the cell walls and can be selected to form a surface film on the wood. 12. The method according to claim 11, characterized in that the larger molecules have a molecular weight of about 20,000 to about 200,000. 13. The method according to any one of claims 1 to 12, characterized in that the resin in the resin-solvent combination is present in an amount of from about 5 to about 70 percent by weight. 14. The method according to claim 13, characterized in that the resin in the resin-solvent combination in an amount from about 5 to about 30 weight percent. 15. The method according to claim 14, characterized in that the resin in the resin-solvent combination in an amount at least about 8% by weight is present. 16. The method according to any one of claims 1 to 15, characterized in that an additional wood treatment chemical in a water-miscible solvent with the Q3004 0/061 Wood is brought into contact to deposit an effective amount of the chemical in the wood's cell walls before the resin in the cell walls is converted to a water-insoluble form, and that thereafter the wood treatment chemical is fixed in the cell walls by converting the resin into a form which is insoluble in water. 17. The method of claim 16 characterized in that the wood treatment chemical is in the same solvent how the resin is present and that it is simultaneously brought into contact with the wood so that the wood treatment chemical and the resin is co-deposited in the cell walls. 18. The method according to claim 16 or 17, characterized in that the wood treatment chemical is selected from the group of wood preservatives and fire retardant or flame retardant agents (fire retardants). 19. The method of any one of claims 16 to 18 characterized in that the wood treatment chemical is selected is from the group of wood preservatives and fire retardants and that the water-miscible organic liquid makes up no more than about 10 percent by weight of the resin-solvent combination. 20. The method according to claim 19, characterized in that the water-miscible organic liquid is not than about 5 parts by weight of the resin 7 _O solvent combination constitutes more. 21. The method according to claim 19 or 20, characterized in that 030040/0618 net that the wood treatment chemical used is water soluble is. 22. Wood treatment agent, characterized in that that it contains a water-dilutable resin, which is thereby converted into a water-insoluble form It can be exposed to ambient conditions, a water-miscible solvent for the Resin and an effective amount of a wood treatment chemical dispersed in the resin and in the solvent wherein the resin is at least about 10 weight percent molecules having a molecular weight less than about 1000 contains. 23. Wood treatment agent according to claim 22, characterized in that that the solvent contains water and a water-miscible organic liquid. 24. Wood treatment agent according to claim 22 or 23, characterized in that the resin is polymerized Vinyl monomers. 25. Wood treatment agent according to one of claims 22 to 24, characterized in that it contains less than about 10% by weight of the water-miscible organic liquid. 26. Wood treatment agent according to one of claims 22 to 25, characterized in that the resin is in the resin-solvent combination in an amount from about 5 to about 030040/0616 70 % by weight is present. 27. Wood treatment agent according to claim 26, characterized in that that the resin is in the resin-solvent combination is present in an amount of from about 8 to about 30 percent by weight. 28. Wood treatment agent according to one of claims 22 to 27, characterized in that the wood treatment chemical is selected from the group of wood preservatives and fire retardant or flame retardant agents (fire retardants) . 29. Wood treatment agent according to one of claims 22 to 28, characterized in that the wood treatment chemical is a water soluble salt and that the wood treatment agent is less than about 5% by weight of that which is miscible with water contains organic liquid. 30. Wood treatment agent according to one of claims 22 to 29, characterized in that there is a considerable proportion of larger molecules that cannot enter the free cavities in the cell walls can be selected to form a surface film on the wood treated with the wood treatment agent. 31. Wood treatment agent according to claim 30, characterized in that that the weight ratio of high molecular weight resin to low molecular weight resin is about From 95: 5 to about 50:50. Ö30Q40 / 061S 32. Wood treatment agent according to claim 31, characterized in that that the weight ratio of high molecular weight resin to low molecular weight resin is about 90:10 to about 70:30. 33. Wood treatment agent according to one of claims 22 to 32, characterized in that the resin is an acrylic copolymer contains. 34. Wood treatment agent · according to one of claims 22 to 33, characterized in that the resin is in the form of an emulsion. 35. Wood treatment agent according to one of claims 22 to 34, characterized in that the resin contains enough acid groups to make it soluble in an alkaline solution do. 030040/0615