FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)
1. "AN IMPROVED PROCESS FOR PREPARATION OF ANTI-FUNGAL, ANTI-WOOD BORER AND ANTI-TERMITE FORMULATION".
2. APPLICANTS
(a) Name : Deepak Nitrite Limited
(b) Nationality : Indian
(c) Address: "Deepak Complex", National Games Road, Yerawada,
Pune-411 006, Maharashtra State, India
The following specification particularly describes the invention and the manner in which it is to be performed:-
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This invention relates to an improved process for preparation of anti-fungal, anti-wood borer and anti-termite formulation. The said preparation is used for protection of wood and wood-based products such as plywood, blockboard, particle board, flush door, medium density fibre board, etc. The said formulation is added to the Phenol-Formaldehyde (PF),Urea-Formaldehyde (UF) and Melamine-Urea-Formaldehyde (MUF) resin at the time of manufacture of above wood products.
The conventional method for protecting wood products is based on the use of compounds of Boron, Copper and insecticide formulations such as aldrin, lindane and chlorpyrifos. Some of the above referred chemicals are having a narrow spectrum of activity and others are having a broad spectrum of activity. The said chemicals are in the form of powder or aqueous or solvent based formulations and they are added to the resin during the preparation of glue, mixed thoroughly and the chemically treated glue is then applied to the core veneers which then go into assembly of plywood of different thickness followed by hot pressing. In case of particle board or medium density fiber board, the chemicals are added to the glue which is then mixed with the wood particles or fibers and then hot pressed. The presence of the chemical in the glue line and its penetration in the adjoining veneers along with the glue during hot pressing protects the veneers from attack of fungus, wood borers and termites in two different ways-firstly by destroying any infection in the form of fungal spores or wood borer eggs that may be present in the veneers and secondly, in the long run protecting the finished plywood / board from outside attack of insects.
The presence of the anti-fungal chemical in the glue line prevents the fungal attack on the plywood under conditions of high humidity / moisture by inhibiting the germination and growth of fungal spores that are naturally present in the air or on the wood surface. In the absence of any such protective anti-fungal chemical, the decay fungi breakdown the various components of wood enzymatically to forms that they readily assimilate. Such wood is said to be decayed. In the absence of a suitable glue line additive and under moist conditions the plywood is attacked by decay fungi and termites. Under dry conditions wood borers attack plywood, tunneling deep inside the veneers and convert the wood
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into powder. Plywood that has been so attacked by fungus, termite and borer is said to be decayed or rotted and it loses its desirable properties of strength and structure.
The said conventional chemicals have the disadvantages of being acidic in nature and as such they may interfere with the bonding of PF resin and cause delamination of plywood. Copper being a heavy metal is not environment-friendly.
Formulations based on insecticides are unstable, they tend to decompose during hot pressing, and the insecticides being insoluble in water, they give non-uniform protection for a short period of time. Most of these insecticides are highly toxic, sometimes carcinogenic and cause long term damage to workers exposed to them.
In the present invention described hereinafter for an improved process for preparation of anti-fungal, anti-wood borer and anti-termite formulation, the following steps are involved :-
(a) For the manufacture of mixed nitrotoluenes, toluene is treated with a mixture of
nitric acid and sulfuric acid to carry out its nitration and the resultant organic
mixture generated in this reaction contains the major product, i.e. mixed
nitrotoluenes and co-products consisting of a mixture of nitrocresols and other
unidentified products. After the completion of nitration reaction, the organic
mixture is physically separated from the acids, organic mixture is then washed
with alkali to remove the nirtocresols and other unidentified products. These
washings are collectively referred to as 'Black Liquor', which is an aqueous co-
product stream.The said 'Black Liquor' consists of a mixture of nitrocresols and
other unidentified products and is deep red in colour, with a high Chemical
Oxygen Demand (COD) of 29,000 mg/1 to 30,000 mg/1.
(b) Concentrated mineral acids such as Sulfuric acid, Hydrochloric acid is added to
'Black Liquor' to adjust its pH between 6.0 to 0.0 at room temperature under
stirring thereby precipitating the nitrocresols and other unidentified products from
the 'Black Liquor' in the form of 'total precipitated solids'. The precipitation is
carried out by adjusting the pH of the black liquor between 6.0 to 0.0 by addition
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of concentrated mineral acid such as Hydrochloric acid, Sulfuric acid at room temperature. The precipitation is complete in 30 minutes to 60 minutes, the slurry of total precipitated solids is chilled to a temperature ranging from 5 °C to 15 °C and filtered to get a wet cake of total precipitated solids (dark yellow in colour), which is then dried at temperature of 30 °C to 40 °C to yield dry solid, (c) The said dried solid is placed in metal tray and water and an amine type spreader and sticker additive(s) is mixed with it to obtain a homogeneous paste. Amine type additives such as mono-ethylamine, di-ethylamine, tri-ethylamine, etc. are used for this purpose.
The chemical composition of the said dried solid was determined by chromatographic methods. HPLC (High Performance Liquid Chromatography) analysis of the said dried solid revealed the presence of at least 7 to 8 compounds of which 2,6-dinitro- p- cresol was major component constituting about 80 to 85 % w/w of the mixture and minor components 4,6-dinitro-o-cresol and 2,4,6-trinitro-m-cresol which were identified by comparison with known standards. Thin Layer Chromatography (TLC) revealed (solvent system chloroform : methanol :: water 20 ml : 5 ml : 3 drops ) presence of at least 6 compounds of which 2,6-dinitro-p-cresol ,4,6-dinitro-o-cresol and 2, 4, 6-trinitro-m-cresol were identified by comparison with known standards. The said dried solid has soluble in solvents like methanol, ethanol, and mixed xylene and sparingly soluble in water.
ANTI-FUNGAL PROPERTY
Assay methods to evaluate the anti-fungal properties of the said dried solid vis-a-vis known anti-fungal chemicals 2,4- and 2,6-dinitrophenol mixture and pentachlorophenol (PCP) were standardised as follows:
(a) Growth inhibition test
The activity of the sodium salt of the said dried solid was tested against nine fungal cultures obtained in pure from decaying wood, soil and air. The sodium salt of the said
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dried solid was incorporated into the sterile molten growth medium (Yeast Extract Malt Extract Agar) at predetermined concentrations and after solidification of the agar medium, the plate was inoculated with a spore suspension of the test culture and incubated at room temperature. Theplates were checked for growth at 24 h intervals for 8 to 10 days and growth inhibition pattern for the said dried solid and dinitrophenol (sodium salt ) was recorded. The said dried solid (in the form of sodium salt) at the concentration of 100 ppm to 400 ppm allowed good growth with sporulation, at 500 to 900 ppm there was poor growth with sporulation and at 1000 ppm scanty or no growth and no sporulation of all the cultures tested. Dinitrophenol (in the form of sodium salt) at the concentration of 100 to 200 ppm allowed good growth with sporulation, at 300 ppm there was scanty or no growth and no sporulation of all the cultures tested. Pentachlorophenol (in the form of sodium salt) at 100 ppm inhibited growth of eight out of nine cultures tested and at 500 ppm growth of all nine cultures was inhibited. The antifungal property of the said dried solid was more pronounced under acidic conditions than alkaline conditions.
(b) Application test.
To arrive at the practical minimum inhibitory concentration of the said dried solid against fungal infection on wood and to assess the anti-fungal protection offered, clean wood chips (free of fungal infection) were treated with different concentrations of the antifungal chemical by dipping in the solution for a fixed period of time (30 minutes), air dried, and inoculated with the test culture. The inoculated wood chips were incubated in sterile Petri dishes in a humid atmosphere and checked for fungal spoilage. An untreated and uninoculated wood chip alongwith an untreated but inoculated wood chip served as controls. The growth inhibition pattern for the said dried solid, dinitrophenol and pentachlorophenol was recorded. All untreated but inoculated wood chips showed good fungal growth and spoilage. The treated but uninoculated wood chips showed no spoilage. The said dried solid (aqueous solution of sodium salt, pH 3.5 to 5.0) at 1000 ppm to 2000 ppm concentration permitted poor growth of five out of nine cultures tested and at 2500 ppm growth of all cultures was inhibited. Dinitrophenol and pentachlorophenol (aqueous solution of sodium salt) at 1000 ppm concentration showed
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total inhibition of fungal growth on the wood chips. The said dried solid (formulation prepared in mixed xylene) at 1000 ppm to 2000 ppm concentration permitted poor growth of some cultures , at 2500 ppm to 5000 ppm no significant growth of any culture was observed and at 5000 ppm to 10,000 ppm total growth inhibition of all cultures was observed. Similar results were obtained with methanolic solution of the said dried solid.
ANTI-WOOD BORER (Lyuctus sp.) PROPERTY
The anti-wood borer property of the said dried solid was tested by the following application test:
Test pieces of mango and rubber wood (wood types that are rich in starch and very prone to borer attack) were treated by dipping in aqueous formulation (1 % w/w solution of sodium salt of nitrocresols) prepared from the said dried solid and after drying these treated pieces along with untreated controls were exposed to an environment where borer infestation was predominantly present in susceptible wood pieces in a plastic jar. The test pieces were exposed to this natural infection process for a period of one year with intermittent observations.
None of the wood pieces treated with the aqueous formulation prepared from the said dried solid were attacked by borers, whereas the untreated controls were attacked and wood flour was observed to fall from the exit holes of the adult insect. The results indicated that the said dried solid formulation offered resistance to the wood from borer attack. Similar results were obtained with wood pieces treated with solvent based formulation (1 % w/v of the said dried solid)
ANTI-TERMITE PROPERTY
The anti-termite property of the said dried solid was tested by the following application test:
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Test pieces of mango and rubber wood (wood types that are very prone to termite attack) were treated by dipping in aqueous formulation (1 % w/w solution of sodium salt of nitrocresols) prepared from the said dried solid and after drying these treated pieces along with untreated controls, they were exposed to an environment where subterranean termite attack was predominantly present in wood work. The test pieces were exposed to this natural infection process for a period of one year with intermittent observations.
None of the wood pieces treated with the aqueous formulation prepared from the said dried solid were attacked by termites, whereas the untreated controls were attacked and completely destroyed by the termites. The results indicated that the said dried solid formulation offered resistance to the wood from termite attack. Similar results were obtained with wood pieces treated with solvent based formulation (1 % w/v of the said dried solid).
The anti-fungal, anti-wood borer and anti-termite property of the said dried solid vis-a-vis known anti-fungal, anti-wood borer and anti-termite chemicals was evaluated in the laboratory in application tests and the results further confirmed by testing the wood samples treated with aqueous formulation of the said dried solid for fungus, wood borer and termite resistance at reputed National Institutes such as Forest Research Institute, Dehra Dun and Indian Plywood Industries Research and Training Institute, Bangalore. From the application tests it was concluded that the said dried solid offered good protection to wood against fungal, borer and termite attack and spoilage at a concentration of 10,000 ppm and its anti-fungal activity was approximately half that of the well known anti-fungal chemical pentachlorophenol at the same concentration. It was decided to prepare anti-fungal, anti-wood borer and anti-termite formulation containing the said dried solid and use it as an additive in the resin at a final concentration of 1 % w/w in practical application.
COMPATIBILITY OF FORMULATION WITH PHENOL-FORMALDEHYDE
RESIN
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The compatibility of the formulation with PF liquid resin was evaluated in laboratory and pilot plant studies as follows:
1. Laboratory studies.
The formulation based on the said dried solid was added to a commercial sample of liquid PF resin at different concentrations ranging from 0.25 % w/w to 1.5 % w/w, mixed thoroughly to dissolve completely in the alkaline resin and allowed to stand overnight. To arrive at the practical concentration of the said dried solid in the resin, the pH, viscosity, flow time, gel time and shelf life of the chemically treated resin were observed over a period of time and the results recorded. The viscosity (flow time), pH, gel time and shelf life of the resin was not found to be significantly altered at the above mentioned concentrations of the formulation. The formulation based on the said dried solid was acidic in nature and sparingly soluble in water, however, the presence of the additive in the formulation and the free alkali (caustic soda) in the PF resin helped in dissolving the said dried solid from the formulation in the PF resin and converting it to its sodium salt, which is water soluble, by reaction with caustic soda.
From the above tests it was concluded that the formulation based on the said dried solid was compatible with the liquid PF resin without affecting its "Pot Life" and without significantly altering its desirable properties of pH, flow time, gel time and shelf life at the above mentioned concentrations.
2. Pilot plant studies
To the liquid PF glue prepared by dissolving 1 kg PF powder in 1 kg water and adding 200 g Maida (extender), the formulation based on the said dried solid was added at different concentrations ranging from 1 % w/w to 2 % w/w, mixed thoroughly to dissolve completely and the pH, flow time and gel time was measured and bond strength determined of both the plain PF glue and chemically treated PF glue by preparing sample pieces of 4 and 6 mm thickness plywood (l'x 1') using glue and veneers of different
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wood species such as mango, eucalyptus and poplar. Results of these studies confirmed the laboratory findings on compatibility of formulation with PF glue as given below:
pH Flow Time Gel Time
(B 6 Cup) (140 +/- 2 °C)
PFglue 11.25 35 seconds 3 min.21 sec.
PF glue 11.35 35 seconds 3 min.25 sec.
(chemically
treated)
1 % w/w
Hot Press Parameters
Open Assembly Time (Time between gluing and hot pressing) 1 hour Hot Press Temperature (Platen) 140 +/- 1 °C Specific Pressure 16 - 17 kg/m Hot Press Cycle 8 min.
Boards prepared from chemically treated and plain PF glue were subjected to dry and wet shear strength (after 8 hour in boiling water) and results were found to be satisfactory indicating that the presence of the formulation based on the said dried solid in the glue did not adversely affect the bond strength of the glue. Results of these studies are given below:
Wood Glue used Shear strength
Species Dry Wet
Kgf Wood failure Kgf Wood failure
Poplar Plain PF 105 100% 98 100%
125 100% 85 100%
190 80% 93 100%
Average 140 Kgf
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Poplar

PF (chemically
treated) 110
l%w/w 180
135

90% 95% 100%

93 88 105

100% 85% 100%

Average 142 Kgf
3. Plant trials.
Plant trials conducted at several plywood manufacturing units across the country confirmed the compatibility of the formulation based on the said dried solid with the PF glue and plywood manufacturing process and no adverse effect of addition of the formulation on the wet and dry shear strength of the plywood was observed. Results of one such trial for the manufacture of 12 mm plywood are given below:

Species

Dry shear strength Kgf Wood failure

Wet shear strength
Kgf Wood failure

Mango/ 156 95% 146 85%
Garjan 160 100% 130 90%
122 95 % Average 146 Kgf 128 80%
Mango/ 110 80% 62 100%
Eucalyptus 118 95% 110 90%
134 70% Average 120 Kgf 120 90%
Further, the formulation based on the said dried solid was tested as a glue line additive in the manufacture of blockboard (19 mm thickness) at a prominent manufacturer by incorporating the formulation into the PF glue at 1 % and 1.5% w/w level and the formulation was found to be compatible with block board manufacture.
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4. Stability of chemicals in manufactured plywood
The active ingredient in the said dried solid in the formulation was found to be stable to heat during hot pressing cycles of varying length depending on the thickness of the plywood being manufactured and sample pieces of plywood prepared with chemically treated glue on digestion and extraction with hot water /caustic lye solution and analysis on HPLC (High Performance Liquid Chromatography) revealed the presence of nitro-cresols in the active form as detailed below:
Assuming a coverage of 300 square metres for 100 Kg resin for single glue line (both sides gluing) and addition of 1 Kg formulation to 100 Kg PF resin, 1 square inch of 6 mm ply (2 glue lines) contains approximately 0.0033 g cresol Practical observation after 1 year of manufacture is 1 square inch of 6 mm ply (2 glue lines) contains 0.0036 g cresol Results indicate that the said dried solid in the formulation remain stable during hot pressing and subsequent storage of the board , thus providing protection to the wood against possible attack from outside. Chemicals from the glue line were found to be migrating to the adjoining veneers and HPLC analysis of veneers stripped of glue revealed the presence of 0.03 Kg cresol per cubic metre of veneer (mango).
5. Biological testing of finished plywood,
PF plywood prepared from non-durable wood veneers like mango, poplar, semul, rubber wood, etc. were tested in-house for resistance to fungus (Mycological test as per IS 1734 (Part 7): 1983 and IS 4873:1993), resistance to termites ( Accelerated termite resistance test as per IS 4833:1993) and resistance to borers (natural infestation test as prescribed by IPIRTI, Bangalore) as described below and the formulation based on the said dried solid was found to confer good resistance to the plywood against these pests.
Mycological test - Test pieces of PF plywood prepared with formulation based on the said dried solid as glue line additive were subjected to attack of wood rotting fungi under humid conditions for a period of 12 weeks at end of which the weight loss in the pieces was estimated. The formulation gave good protection against fungus attack to the plywood
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Termite resistance test - Test pieces of PF plywood prepared with formulation based on the said dried solid as glue line additive were subjected to attack of subterranean termites by burying them in termite mounds for a period of 6 months and estimating the weight loss at the end of the testing period. The formulation gave good protection against termite attack to the plywood.
Borer resistance test - Test pieces of PF plywood prepared with formulation based on the said dried solid as glue line additive were subjected to attack of wood borers (Lyctus species) in the natural infestation test for a period of 8 months and the extent of damage to wood was assessed. The formulation gave good protection against borer attack to the plywood.
COMPATIBILITY OF FORMULATION WITH UREA-FORMALDEHYDE RESIN
The compatibility of the formulation with UF liquid resin was evaluated in laboratory and pilot plant studies as described for PF resin and the formulation was found to be compatible with UF resin. The only difference was for dissolution of the formulation in UF resin it was necessary to add liquor ammonia to maintain pH at desired level.
FORMULATION
The glue line additive formulation prepared from the said dried solid was found to be very effective in preventing the attack of fungus, borer and termite on plywood as determined in application tests at different plywood manufacturers.
ADVANTAGES
The major advantage of this invention is that, unlike the conventional glue line additive chemicals, the said dried solid formulation is free of highly toxic and chemically unstable insecticides, it is stable and does not decompose at hot press temperatures and it does not lose activity over a period of time, no toxic fumes are emitted during hot pressing as no thermal degradation takes place, it does not adversely affect the rubber rollers of glue
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spreader as it is free of organic solvents and it does not adversely affect the bond strength as observed with some other acidic glue line additives commercially available. The improved process used for the preparation of this formulation confers on it the singular advantage of even spreading of the chemical in the glue line and further movement from the glue line to the adjoining veneers for effective protection of the entire thickness of the plywood.
The 'Black Liquor' generated during nitration of toluene is otherwise a waste stream, which is put to good use by manufacturing a glue line additive formulation from it and simultaneously taking care of the environmental pollution problems.
This invention will now be illustrated in greater detail with reference to the following examples, but it should be understood that the present invention is not limited thereto.
EXAMPLE 01
To a beaker equipped with a stirrer and a thermometer, 1000 ml of black liquor was charged and concentrated sulfuric acid (11.6 g, 98 % w/w strength) added dropwise under stirring. The resultant mixture was stirred for 30 minutes to complete precipitation at a pH between 0.0 to 6.0.The contents of the beaker were then chilled to 5-15 °C and the slurry of total precipitated solids was filtered and wet cake dried at 35 °C to yield about 26.0 g of the said dried solid.
Glue line additive formulation - To a beaker equipped with a stirrer, sufficient quantity of the said dried solid and water was charged successively and amine type spreader and sticker additive (s) was added dropwise. The mixture was stirred slowly to mix the contents of the beaker thoroughly so that the additive (s) and the said dried solid formed a homogeneous paste with water. The formulation prepared as above was more effective in protecting wood than the conventionally used glue line additives.
EXAMPLE 02
The said dried solid obtained as shown in Example 01 was used for preparing glue line additive formulation with the same set up as shown in Example 01 using mono-ethylamine in place of amine type spreader and sticker additive (s).
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EXAMPLE 03
The said dried solid obtained as shown in Example 01 were used for preparing glue line additive formulation with the same set up as shown in Example 01 using tri-ethylamine in place of amine type spreader and sticker additive(s).
While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.
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We claim:
(1) A process for the preparation of anti-fungal, anti-wood borer and anti-termite formulation comprising the following steps:-
(a) nitration of toluene with acid such as nitric and sulfuric to obtain mixed nitrotoluenes and other co-products.
(b) separation of the said mixed products by washing with alkali to remove nitrocresols and other unidentified products hereinafter referred to as 'Black Liquor',
(c) taking the 'Black Liquor' and adding concentrated mineral acid such as sulfuric acid and hydrochloric acid at room temperature under stirring to precipitate the nitrocresols and other unidentified products as 'total precipitated solids and the same is chilled at 5°C to o 15 ° C and thereafter dried at 30 ° C to 40° C to yield the dried solid,
(d) mixing the said dried solid with water and amine type spreader and sticker additive(s) under stirring to give a homogeneous paste which is an anti-fungal, anti- wood borer and anti-termite formulation .
(2). An improved process for preparation of anti-fungal, anti-wood borer and anti-termite formulation as claimed in claim 1, wherein amine type spreader and sticker additive (s) used is mono-ethylamine, di-ethylamine, tri-ethylamine.
Dated this 17 th day of January, 2006

BHARAT S.SHAH Duly Constituted Attorney
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ABSTRACT
A process for the preparation of anti-fungal, anti-wood borer and anti-termite formulation comprising (a) nitration of toluene with acid to obtain mixed nitrotoluenes and other co-products, (b) separation of the said mixed products by washing with alkali to remove nitrocresols and other unidentified products hereinafter referred to as 'Black Liquor', (c) taking the 'Black Liquor' and adding concentrated mineral acid at room temperature under stirring to precipitate the nitrocresols and other unidentified products as 'total precipitated solids and the same is chilled at 5°C to o 15 ° C and thereafter dried at 30 °C to 40° C to yield the dried solid, (d) mixing the said dried solid with water and amine type spreader and sticker additive(s) under stirring to give a homogeneous paste which is an anti-fungal, anti- wood borer and anti-termite formulation .
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