Method of waterproofing a wood powders

 

(57) Abstract:

The invention relates to a method for gidrofobizirovannogo dispersed wood intended for use as a filler in polymer materials. Describes a method of waterproofing a wood powders, including thermochemical processing of their chemical compound. The method differs in that the dry powder is impregnated with at normal temperature 1-10 wt. % solution in chloroform or hexane pine oleoresin, consisting of 75-76% diterpene resin acids of the formula C19H29COOH, 16-18% of turpentine or monoterpenic hydrocarbons of the formula C10H16and up to 6% of water for 17 h, after which the impregnated powder is dried from the solvent at 60oC to constant mass and incubated at 150-180C for 6 hours Obtained hydrophobizated powders retain the positive properties of the starting powders (particle size, low specific weight and high resistance to water absorption with a low content of water-repellent. table 1.

The present invention relates to a method for gidrofobizirovannogo dispersed wood intended for use as a filler politiskie physico-mechanical, art-decorative and other useful properties. Having in mind the large number of substandard wood and the problem of its disposal, considerable interest is the use of it in a relatively new quality - cheap dispersed filler heavy hydrocarbon polymers - polyethylene, polypropylene, etc. In this case, it is necessary to ensure its compatibility with polymers. So the introduction of crushed wood (flour) in the polyethylene reduces the strength of the products due to weak surface interactions, whereas in the case of secondary polyethylene containing a polar group, there is an increase in strength [E. P. Mamunya, V. D. mysak, D. Semenovich. Vysokomol.Conn.1994. T A 36 N 8, S. 1358]. The same is observed for the functionalized polypropylene. Similarly, grafting of organic groups on the wood filler, i.e., hydrophobicity, improves compatibility with polyolefins and increases physical and mechanical characteristics [M. M. Sain, B. V. Kokta. Polim. Plast.Technol. and Eng - 1994. V. 33.N 1. P. 88].

Thus, the use of dispersed wood fillers in the compositions and hydrocarbon polymers involves the modification of the polymer or nigerianization) wood fillers available (cheap) reagents is preferred to the reception, than modification of the polymer.

Known methods of increasing the stability of dispersed wood to the action of moisture. So steaming wood flour and process it before drying a dilute solution of sulfuric acid improves the resistance due to the removal of wood amorphous (soluble) [Ed.mon. USSR N 1518123]. Processing of wood powder in the vapor phase organic matter (bitumen, tar, paraffin) when 160-350oC in the vortex dryer increases the resistance and strength of powders [Ed.mon. USSR N 1723072].

More efficient combined methods of improving water resistance. For example, thermal (temperature measurement from 800 to 75o) and subsequent two-stage chemical treatment of wood particles 2 to 10% solution of calcium chloride at 20-30oWith, and then 2 to 15% solution of sodium silicate [Ed.mon. N 1433400] . A significant (2-3-fold) reduction in water absorption of the wood is achieved by sequential processing of the first 30% solution of trichlorotriazine in CCl4and then 10% toluene solution of methylprednisolone, and fixing organosilicon does not occur in the absence of primary processing [E. N. Pokrovsky, V. I. Sidorov, N. N. Melnikova. Chemistry of wood-Onno-active, seriously volatile compounds, which imposes stringent requirements on process technology.

Optimal from the point of view of reducing the water absorption of the dispersed wood way is in thermochemical processing using oligomeric gmailassistant or mixed alkoxysilanes [U.S. Pat. RF N 2126774]. It includes the impregnation of wood powder oligoastrocytoma for 15 - 20 min, followed by heat treatment at 100-180oC for 1 h Products heat treatment containing from 4 to 40 wt.%. compounds of silicon (ash), characterized in ~ 10 times less water absorption (compared to untreated samples) and in addition a slight increase resistance to burning and biodegradable. The last two indicators of interest from the standpoint of stability of the product during storage.

The disadvantages of this method of waterproofing is using to achieve the effect of hydrophobization of significant quantities of water-repellent (from 4 to 40% by weight). In addition, reduced water absorption is large in comparison with the original wood powder (575 up to 40-60%), but not in absolute value.

The authors of the invention proposes a method of thermochemical hydrophobization drevesiny adaptability. This is achieved through thermo-chemical processing of wood powders pine resin, representing the natural resin of medium composition: 75 - 76% diterpene resin acids gross formula C19H29COOH, 16-18% of turpentine or monoterpenic hydrocarbons gross formula C10H16and up to 6% water. The process involves impregnation of the powder is 1 to 10% wt. solutions of the resin in chloroform or hexane for 17 h and after drying at 60oC to constant mass, heat treatment at 150 - 180oC for 6 hours, the Temperature and time of thermal treatment were selected depending on the conditions of the reaction of esterification of resin acids resin hydroxyl groups of the wood and the sustainability of the source powder and the reaction products.

Method of waterproofing according to the present application is illustrated by the following examples.

Example 1

Wood powder as flour (10 g) with a particle size of 100 to 150 mesh was dried in vacuum at 60oC to constant weight. Then poured the excess impregnating solution - 10% wt. in chloroform pine oleoresin, consisting of 75-76% diterpene resin acids of the formula C19H29COOH, 16 - 18% of turpentine or monoterpenic hydrocarbons of the formula C10HoC to constant weight. Samples with adsorbed on the resin were placed in a furnace for heat treatment at 150oWith 6 hours after that time, the powders were weighed and kept in a desiccator.

For the obtained sample was determined from 3-5 concurrent measurements of water absorption (according to GOST 16483.20-72), wettability (the behavior of water droplets deposited on a plate of pressed powders, characterized apparent boundary contact angle), the coefficient of hydrophilicity (the ratio of the heats of wetting of powders with water and hexane, defined calorimetrically; a value greater than 1 indicates a preferential wetting by water, and a smaller 1 - hexane), and sorption of hydrocarbons - oil (on the maximum amount of oil sorbed 1 g of the powder sorbent in the system oil-water. The results are shown in table (op.2). It contains: data for sample according to the op.2 processed at a temperature of 180o(Op.3): for samples of powders with other contents sorbed and associated pine oleoresin obtained by changing the con the data) powder. From the data table. it can be concluded that as a direct experiment (water absorption) and indirect tests (wettability, the coefficient of hydrophilicity, sorption of hydrocarbons - oil), indicate the hydrophobization of the surface of powders and accordingly reduce the hydrophilic properties inherent in the original wood powder. Thus, the treated resin powders practically cannot be wetted with water, and the values of boundary wetting angles (117 - 149o) significantly exceed 90o(for the original sample - full wettability and boundary angle of zero). To increase the hydrophobic properties of point values of the coefficient of hydrophilicity, smaller units (for the original sample of 1.35) and high sorption capacity with oil (-6 g/g sorbent compared to 2.2 for the original powder). As a result of changes in the properties of the surface in the direction of waterproofing samples processed resin powders was characterized by low water absorption (-10 - 30%) compared with 570% (of the original sample). This is less than for the samples according to the prototype, for which a similar indicator was changed in the range of 40 - 60%.

It should be noted that the hydrophobicity of the dispersed pine wood resin is observed for low absolute reality decreases with increase in the number of bound resin (op.2-5). Let us note that in the case of the prototype, the amount of bound silicon repellent significantly more from units to tens of percents. This suggests, on the one hand, about the effectiveness of the process of waterproofing chemical linking components of wood resin powder. On the other hand, a higher than optimal, the number of water-repellent-resin reduces the effectiveness of waterproofing due to the effect of "peremeshivanija" surface, when the excess molecules of water-repellent due to the orientation of the polar groups on the surface of the consumption of other related molecules, reducing the effect of waterproofing due to the appearance of affinity for water. Indeed, the number of linked resin above 10% (from theory), i.e. higher than in the op.2 and 3 (table), significantly increase the water absorption of the samples. As for lower bounds linked resin (op.8 and 9, 0.03 g/g of sorbent or -2% of theory), further lowering its impractical because of the need to use very dilute solutions of resin in chloroform (1% and below). This significantly slows down the process of adsorption and increases the total duration of thermochemical process of waterproofing.

Way gidrofobizator dry powders impregnated with at normal temperature 1 - 10 wt.% the solution in chloroform or hexane pine oleoresin, consisting of 75 - 76% diterpene resin acids of the formula C19H29COOH, 16 - 18% of turpentine or monoterpenic hydrocarbons of the formula C10H16and up to 6% H2O, for 17 h, after which the impregnated powder is dried from the solvent at 60oC to constant weight and maintained at 150 - 180oC for 6 hours

 

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