a first type of waterproofer which is contemplated for the systems of the present invention are alkyl amine oxides . these amine oxides have the general formula ## str2 ## wherein r 7 contains from 8 to 40 carbon atoms and is saturated or unsaturated . r 8 and r 9 may be methyl , ethyl , propyl , isopropyl , hydroxyethyl , hydroxyethoxyethyl or hydroxyethyl polyethoxyethyl radicals where the oxygen is linked to nitrogen by a coordinate covalent bond . if desired , r 8 and r 9 may be linked to form a cyclic group . while all of the listed amine oxides have waterproofing function , those with greater than 14 carbons in its alkyl group are particularly effective . ( a ) octadecyldimethylamine oxide , where r 7 is 18 and r 8 and r 9 are methyl , and ( b ) hexadecyldimethylamine oxide , where r 7 is 16 and r 8 and r 9 are methyl . a second type of waterproofer contemplated for use in the present invention comprises waterproofing quaternary ammonium compounds having the formula : ## str3 ## wherein r 11 is a c 12 - c 30 alkyl or c 6 - c 20 aryl - substituted alkyl , and r 12 is a c 12 - c 20 alkyl . preferably , in a waterproofing quaternary ammonium compound , r 11 is a c 12 - c 30 alkyl , and r 12 is a c 12 - c 30 alkyl group . x may be a halide , including chloride , bromide , fluoride , iodide , or a carbonate , methosulfate , ethosulfate , acetate , propionate , hydroxide , ethylhexanoate or any other counteranion disclosed in u . s . pat . nos . 5 , 399 , 762 or 5 , 559 , 155 . thus , the total number of carbon atoms is r 11 + r 12 ≧ 24 . more preferably , r 11 is a c 12 - c 18 alkyl group , and r 12 is a c 12 - c 18 alkyl group . two preferred waterproofing quaternary ammonium compounds are di ( c 12 to c 18 ) dimethylammonium chloride and ditallowamidoethyl polyoxyethylene - methylammonium methosulfate . a final type of waterproofer contemplated for use in the present invention comprises alkyl acetoacetates having the formula : ## str4 ## wherein r 10 is an alkyl group containing 8 to 40 carbon atoms , though preferably 12 to 20 carbon atoms , and is saturated or unsaturated . r 10 is c 18 in a preferred alkyl acetoacetate . special mention is made of octadecyl acetoacetate available from lonza ag . also contemplated by the present invention are combinations of any of the above with each other , with esters or with small amounts of low molecular weight polyolefins or other waxes or resins . these waterproofers hinder migration of the quat molecules from a substrate under wet conditions . furthermore , where surface corrosion problems are related to the water holding properties of the quat , the waterproofer displaces or prevents the entry of water . quaternary ammonium compounds are specifically contemplated for use as a biocide in the treatment systems of the present invention . biocidal quaternary ammonium compounds have the formula : ## str5 ## wherein r 11 is a c 1 - c 20 alkyl or c 6 - c 20 aryl - substituted alkyl group , r 12 is a c 6 - c 20 alkyl group . x may be a halide , including chloride , bromide , fluoride , iodide , or a carbonate , borate , carboxylate , methosulfate , ethosulfate , acetate , propionate , hydroxide , ethylhexanoate or any other counteranion disclosed in u . s . pat . nos . 5 , 399 , 762 or 5 , 559 , 155 . an example is didecyldimethylammonium chloride . another example is didecyldimethylammonium carbonate . quaternary ammonium compounds which have biocidal properties include those where r 11 is a c 6 - c 18 alkyl or a benzyl group , and r 12 is a c 6 - c 18 alkyl group . thus , the total number of carbons is r 11 + r 12 = 16 - 24 . preferably , r 11 is a c 8 - c 12 alkyl group , and r 12 is a c 8 - c 12 alkyl group . when r 11 is benzyl , r 12 is preferably c 12 - c 16 alkyl group . special mention is made of quats wherein r 11 is a c 8 alkyl , c 9 isoalkyl , c 10 alkyl , c 12 alkyl , or benzyl group ; and r 12 is a c 10 alkyl , c 12 , c 14 alkyl or c 16 alkyl group . a preferred chloride quat is didecyldimethylammonium chloride wherein r 11 and r 12 are a n - c 10 group . this quat may be usefully applied in the form of an 80 % water / ethanol solution ( bardac ® 2280 ; lonza inc .). useful carbonate quats have the above - shown formula wherein r 11 is a methyl , c 8 alkyl , c 9 isoalkyl , c 10 alkyl , c 12 alkyl , c 14 alkyl , c 16 alkyl , or benzyl group ; and r 12 is a c 10 alkyl , c 12 alkyl , c 14 alkyl , or c 16 alkyl group . a preferred carbonate quat is didecyldimethylammonium carbonate wherein r 11 and r 12 are a n - c 10 alkyl group . didecyldimethylammonium carbonate , as a 70 - 80 percent ( by weight ) solution , is a yellow / orange liquid that has a slightly fruity odor . this formulation has a flash point of about 160 ° f ., and reacts with carboxyl containing compounds . this carbonate quat is made by the method disclosed in u . s . pat . nos . 5 , 523 , 487 and 5 , 438 , 034 . one or more of the carbonate quats alone or in combination with the corresponding chloride quat can be formulated in the present waterproofer wood preservative systems . the two principle components of the present waterproofer and preservative system , the waterproofer and the biocide , should be combined in amounts which allow the waterproofer to prevent exposure of the treated wood to water and the biocide to function against biological attack , such as fungal growth . in general , a ratio of waterproofer to biocide of 1 : 1 has been found effective , with a range of 0 . 25 : 1 to 1 : 0 . 25 anticipated to be within the functional range . the concentration of waterproofer found effective is 0 . 25 - 4 wt %, more particularly , 0 . 5 - 2 wt %. the concentration of biocide found effective is 0 . 25 - 4 wt %, more particularly , 0 . 5 - 2 wt %. the following examples illustrate the invention without limitation . all parts and percentages are given by weight unless otherwise indicated . treating solutions were prepared by mixing the appropriate weight of the waterproofer and quaternary ammonium compound , warning on a hot water bath to melt / dissolve the components into each other and then diluting with warm ( 40 - 50 c ) water with good stirring . the wood treated was either ponderosa pine or southern yellow pine ( syp ) end - grain wafers . the dimensions of the ponderosa pine pieces are 5 &# 34 ;× 0 . 75 &# 34 ;× 0 . 25 &# 34 ; and the syp are 3 . 5 &# 34 ;× 0 . 75 &# 34 ;× 0 . 25 &# 34 ;. the specimen were equilibrated at ambient conditions before treating and were weighed . the samples were then placed in a vacuum desiccator equipped with an addition funnel and evacuated to a pressure ( vacuum ) of 0 . 1 atmosphere for 15 minutes . the treating solution was added to the sample and the pressure in the desiccator increased to atmospheric . the samples were allowed to remain in the solution for five minutes , then removed , blotted , and allowed to air dry to constant weight . the control tws material , which is available in mineral spirits , was applied to samples via a simple one minute soak procedure . soaking experiments were carried out by immersing weighed measured samples in deionized water for 30 minutes . the samples were removed , surface water was blotted and the samples were weighed and the weight percent of water absorbed was calculated for each sample . after the swelling experiment , the samples were air dried and then placed outside on a flat piece of plywood for exposure to the weather . periodically , the samples were returned to the laboratory , air dried to constant weight and once again soaked for 30 minutes and the water uptake determined . water uptake for the last measurement available is given in the tables . data are reported in several tables . since wood can vary , care was taken to use only matched specimens in each table grouping . waterproofing ability is judged by the amount of water that is absorbed by a wooden specimen on immersion for a give time in water . waterproofing index numbers ( wr index ) were calculated by comparing a treated sample with a matched untreated control specimen using the following equation : ## equ1 ## any positive index number indicates a degree of waterproofing for the composition . higher numbers are better than low numbers . a formulation that totally prevents water absorption would have a rating of 100 . for certain millwork applications , an index of 60 is required . any positive number indicates some degree of waterproofing while higher numbers signify the best materials . index numbers of 60 or higher signify particularly good waterproofers . by this criterion , all of the identified materials are good waterproofers . the waterproofing properties are compared to both a non - biocidal waterproofer , thompson &# 39 ; s waterseal ®, available in mineral spirits in the over - the - counter marketplace and a quat combination with pghms which is the subject of u . s . ser . no . 08 / 074 , 314 . data are collected in nine tables and figures . for each table , columns give the name of the waterproofer ( wr ), the name of the biocide or quat ( b ), the amount of each in component in percent , the water uptake of initially treated samples after 30 minutes soaking , the calculated waterproofing index number ( wr index ), and the percent uptake after weathering for a given time . figures corresponding to the data in the tables are also included ( see fig1 - 9 ) showing the percent water uptake ( for thirty minute soaks ) as a function of the number of days of weathering . for each series of samples ( represented by a given table ), a matched set of end - faced wood samples were used . the control in each series is used as the basis for experimental result calculations in that series . in general , the results demonstrate that while prior art compounds such as tws are initially as effective as the combinations of this application , only the presently taught wood preservation systems are effective over long periods of weathering . thus , as evident in the tables which follow , tws , dt95 , pghms and bx18 with dda co3 all show similar waterproofing properties at the early measurement times , but after three years , wood treated with tws or pghms + dda co3 have similar profiles to the untreated control , whereas the new combinations disclosed here performed well after three years . table i______________________________________ponderosa pine treated controls with dda co3 dt95 % uptake wr % uptakewr b wr : b start index 870 days______________________________________control none 70 0 158tws none 9 87 107 dda co3 0 : 1 56 20 143 ddac 0 : 1 53 24 182pgmhs dda co3 1 : 2 26 63 142pgmhs dda co3 1 : 1 24 66 146______________________________________ these data indicate that quats alone are not good waterproofers and any function which they have is quickly lost over time . further , combining pgmhs and dda co3 helps initially to retain the waterproofing function . table ii______________________________________ponderosa pine treated with dda co3 and bx18 and dt95 % uptake wr % uptakewr b wr : b start index 900 days______________________________________control 56 0 125tws 8 86 98bx18 dda co3 1 : 1 12 78 52pghms dda co3 1 : 1 9 84 112dt 95 none 10 82 46dt 95 dda co3 1 : 1 11 80 53______________________________________ these data indicate that bx18 and dt 95 are both effective in combination with the quat , and show significant retention of the waterproofing qualities over time . surprisingly , the systems combining dda co3 with bx18 or dt 95 retain waterproofing ability significantly longer than tws or pghms combined with dda co3 . table iii______________________________________ponderosa pine treated with ddac and dda co3 and dt95 % uptake wr % uptakewr b wr : b start index 780 days______________________________________control 63 0 116tws 12 81 99dt 95 ddac 0 . 5 : 1 31 51 78dt 95 ddac 1 : 1 21 67 61dt 95 ddac 2 : 1 20 68 42dt 95 dda co3 0 . 5 : 1 38 40 87dt 95 dda co3 1 : 1 24 62 57______________________________________ these data indicate that both ddac and dda co3 are effective in combination with dt 95 , particularly after long weathering times . table iv______________________________________ponderosa pine treated with dda co3 and odaa , dt 95 % uptake wr % uptakewr b wr : b start index 780 days______________________________________control 64 0 142tws 10 84 100odaa dda co3 0 . 5 : 1 19 70 70odaa dda co3 1 : 1 19 70 61dt 95 dda co3 1 : 1 32 50 67dt 95 none 1 : 0 18 72 62______________________________________ these data indicate that a 1 : 1 ratio between waterproofer and biocide is effective . table v______________________________________ponderosa pine with ddac and 868 % uptake wr % uptakewr b wr : b start index 640 days______________________________________control 65 0 118tws 11 83 88868 ddac 0 . 5 : 1 39 40 69868 ddac 0 . 75 : 1 36 45 63868 ddac 1 : 1 30 54 71______________________________________ these data show that 868 is an effective waterproofer in combination with ddac and shows excellent retention of properties over time . table vi______________________________________ponderosa pine treated with dda co3 and bx18 % uptake wr % uptakewr b wr : b start index 780 days______________________________________control 59 0 120bx18 dda co3 0 . 5 : 1 28 53 58bx18 dda co3 0 . 75 : 1 20 66 45bx18 dda co3 1 : 1 19 68 37______________________________________ these data show that bx18 is an effective waterproofer over a range of wr : b ratios shown . table vii______________________________________ponderosa pine treated with ddac and bx18 and bx16 % uptake wr % uptakewr b wr : b start index 540 days______________________________________control 70 0 . 00 121tws 7 90 49none ddac 0 : 1 52 26 103bx16 ddac 1 : 1 22 69 71bx18 ddac 1 : 1 11 84 58______________________________________ these data indicate that the c 16 and the c 18 compounds are both effective . table viii______________________________________southern yellow pine treated with dda co3 and bx18 % uptake wr % uptakewr b wr : b start index 780 days______________________________________control 54 0 121tws 9 83 136bx18 dda co3 1 : 1 18 67 37______________________________________ these data indicate that good results can be achieved with bx18 on both southern yellow , as well as ponderosa pine . again , the data in table viii highlight the long term effectiveness of the waterproofer system of the invention . table ix______________________________________southern yellow pine treated with ddac and bx18 , odaa % uptake wr % uptakewr b wr : b start index 725 days______________________________________control 51 0 128bx18 none 1 : 0 30 41 47bx18 ddac 1 : 1 38 25 67odaa ddac 1 : 1 17 67 106______________________________________ this data show odaa together with ddac is also effective on southern yellow pine .
the present invention provides a waterproofing wood preservative system comprising a waterproofer selected from the group consisting of an alkyl amine oxide , an alkyl acetoacetate , and a waterproofing quaternary ammonium compound and a biocide comprising at least one biocidal quaternary ammonium compound wherein said waterproofing quaternary ammonium compound is a c 12 - c 30 alkyl or c 6 - c 20 aryl - substituted alkyl , c 12 - c 30 alkyl quaternary ammonium composition and said biocidal quaternary ammonium compound is a c 8 - c 12 alkyl or c 6 - c20 aryl - substituted alkyl , c 8 - c 10 alkyl quaternary ammonium composition . said wood preservative system offers protection against both biological and physical decomposition of wood , as for example , that occurring in long term - weathering .