|Title of Invention||
A PROCESS FOR PRODUCING COMPREGS FROM BAMBOO MATS/VENEERS OF PLANTATION TIMBER OR A COMBINATION THEREOF.
|Abstract||This invention relates to Compregs from Bamboo Mats/Veneers of plantation timber or a combination and a process for the preparation thereof comprising steps of :- - coating of bamboo mats/veneers with phenol formaldehyde resin followed by drying; - heating of the assembly of mats/ veneers or a combination thereof in a hydraulic hot press fitted with platen or specially designed moulding dies followed by cooling and stabilization.|
|Full Text||FIELD OF INVENTION
This invention relates to compregs from Bamboo Mats/Veneers of plantation timber or a combination and a process for the preparation thereof.
Imported timber is presently used for the development of compregs of 8mm thickness. The compreg requirement by Indian Railways alone is increasing many folds as thrust now is on the use of high strength materials in coach building. Currently for the raw materials, the industries are dependent on imported timbers and also the product is very expensive.
OBJECTS OF THE INVENTION
An object of this invention is to propose compregs from Bamboo Mats/Veneers of plantation timber or a combination and a process for the preparation thereof. It can be used in transformer industries as electrical grade compregs. This acts as a wood alternative and reduces consumption of wood in the form of wood veneers. This would ease the pressure on import of timber.
Another object of this invention is to propose compregs from Bamboo Mats/Veneers of plantation timber or a combination and a process for the preparation thereof, which may be used for railway coaches viz., the seats and berths.
Yet another object of this invention is to propose compregs from Bamboo Mats/Veneers of plantation timber or a combination and a process for the preparation thereof which has high strength properties and is economical.
Further objects and advantages of this invention will be more apparent from the ensuing description.
STATEMENT OF INVENTION
According to this invention there is provided a process for producing compregs from Bamboo Mats/Veneers of plantation timber or a combination thereof comprising steps of :- coating of bamboo mats/veneers with phenol formaldehyde resin followed by drying; - heating of the assembly of mats/ veneers or a combination thereof in a hydraulic hot press fitted with platen or specially designed moulding dies followed by cooling and stabilization.
DETAIL DESCRIPTION OF THE INVENTION
According to this invention, bamboo mats are dipped in diluted resin of phenol formaldehyde for 10-30 minutes, which is prepared by reacting phenol and formaldehyde in the ratio of 1:1-1:3 and in the presence of an alkali catalyst such as Sodium Hydroxide (NaoH) wherein concentration of resin is 25-30%. The viscosity of the resin maintained around 40 - 400 centipoise at 25°C with total dry solid content being 30-60%, which possesses water tolerance of 1:5-1:30. The mats are dipped/soaked in resin solution for the stipulated period depending on the thickness of sliver used.
After squeezing out of excess resin, the resin coated mats are stabilized for a period of 20-200 minutes in open air followed by drying till the moisture content is brought down to 4-16%.
The drying is carried out in a drying chamber or band dryer or in open air for 0-24 hrs depending upon the ambient temperature.
The veneers from plantation timbers of thickness lmm-3mm are dried to a moisture content of 4% - 10%. The veneers are then passed on through a glue spreader to coat the veneers with PF resin which is same as given for bamboo mats.
The glue coated veneers are subjected to open air drying for about 2-6 hours so as to bring down the moisture content of glue coated veneers to 14%- 20%.
The mats assembly comprising of 2-30 mats or 1-50 veneers or combination of 10-20 mats and 1-30 veneers. Number of mats or veneers in the assembly depends on the thickness of compreg required. They are loaded into a hydraulic hot press fitted with specially designed platens or moulding dies with heating and cooling arrangement and released after stipulated time of pressing wherein hot pressing is done at 120-180°C for 3-30 minutes depending upon thickness at a pressure of 50-150 kgs/cm2 and cooling is carried out for about 20-60 minutes so as to bring down the temperature to 80°C.
Thereafter, the compregs are downloaded from hot press and stacked horizontally for 0-72 hrs for stabilization in open air. Finally the sheets are trimmed and kept ready for dispatch.
A high tonnage hydraulic hot press fitted with platens or specially designed moulding dies with heating and cooling arrangements are used in the production of bamboo mat compregs. These compregs possess high strength properties and are dimensionally stable.
The thickness of compregs depends upon the thickness of slivers and number of mats used. The compregs may be made of mats or veneer /veneer and mats in combination. The compregs described above may be provided with phenolic film overlays and release film on either side.
Woven bamboo mats of size 50 cms x 50 cms are taken. Fifteen number of such mats are soaked in phenol formaldehyde resin solution stacked to drain out excess resin, which is dried for 10 minutes for 7% moisture content and then assembled. The total assembly of mats are placed between the platens or moulding dies in the hydraulic hot press and pressed for 22 minutes at 80 kg/cm2 pressure and at 150°C. The pressed panel is cooled to 80°C under pressure in the hot press and removed. The compregs are then conditioned for 48 hours in air. Thereafter, the moulded compreg is given usual finishing before use.
It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims: -
|Indian Patent Application Number||777/CHE/2006|
|PG Journal Number||01/2011|
|Date of Filing||27-Apr-2006|
|Name of Patentee||INDIAN PLYWOOD INDUSTRIES & TRAINING RESEARCH INSTITUTE,|
|Applicant Address||P.B. NO. 2273, YESHWANTHPUR P.O. TUMKUR ROAD, BANGALORE-560 022, INDIAN INSTITUTE|
|PCT International Classification Number||B 27 D 1/00|
|PCT International Application Number||N/A|
|PCT International Filing date|