HEMP AS

A RAW MATERIAL FOR PAPER MAKING

Final YearPulp and Paper Technology.

Seminar by,

Miss. Mayuri Kalane.

Hemp:Hemp is a

Herbaceous annual plant with a single, unbranched stem which grows over 4-5 months growing season to a height of about 5 m & dia.50-60mm

Hemp:Hemp is known for its long and

durable soft fiber. botanical name Cannabis sativa L.Hemp is an annual shrub with ,yield

12-14 tons of dry matter/hector.Hemp stem is divided into two parts:-• Hemp Core- Relatively thin outer

layer.• Hemp Bast – inner woody part.

Hemp:Hemp Core Constitutes

30 to 35% of fiber, with fiber length 20 to 55mm & width 16 to 50 µm.

Hemp Bast comprises about 65-70% fiber, with fiber length 0.5 to 0.6 mm & width 15 to 25 µm.

Need Of hemp:

One of the major industries depending on forests is the pulp and paper industry which uses the woody /non-woody fiber obtained from forest.

But obtaining the continuous supply of such woody fibers from the fragile

forest ecosystem in the future will become more and more difficult.

The reasons for this potential short supply of wood are:

pressure from the environment over-harvesting, sustainable forest management

which allows less cuts per year though it aims to supply fibers for many more years.

demands from social corners like recreational facilities.

Address to the problem of short supply of wood and increasing

demands: Improve the technology to make

the best use of available fibers. use other fiber resources Like

non-woods.promote more recycling of paper. make best use of the available

residues of round wood from other industries for pulp-making.

As a result industries are looking either for inventing changes in the technology to improve the efficiency of the use of harvested wood or research for some alternative raw materials.

In fact, from16" century to 18" century, much of the pulp produced was from non-woody fiber, especially from hemp.

But due to the developing new technologies and cheaper woody fibers resulted in the decline of hemp .

Narcotic Issue of Hemp There are many different varieties of

cannabis plants. Marijuana and hemp come from the same species of plant, Cannabis sativa L.

but from different varieties or cultivars. However, hemp is genetically different and is distinguished by its use and chemical makeup.

Hemp contains only 0.3-1.0% of THC

(delta-9 tetrahydrocannabinol, psychoactive chemical).

THC.

Marijuana refers to the flowering tops and leaves of psychoactive cannabis varieties, which are grown for their high content of THC about 10%; some sample tests indicate THC levels reaching 20%-30%, or greater.

As well growing Hemp for THC is uneconomical

Marijuana and Hemp are easily differentiable.

Reasons for using Hemp : Hemp can help to provide sustainable

fiber resource for pulp production5-8 tones of fiber per acres.

Also hemp cultivation needs moderate use

of fertilizers. o Nitrogen :12 kg/ton of dry matter.o Potassium: 15 kg/ton of dry matter.o Phosphorous: 4 kg/ton of dry mater.

Use hemp can decrease the pressure on forests and the environment.

less energy is required for using hemp in pulp production.

Lignin content in hemp is less than that of wood, which means less use of chlorine for pulping, bleaching and potential increased use of alternative methods of non-chlorine bleaching.

Fine quality paper from hemp can be recycled 7to 8 times.

Soil condition:Site Requirement:Hemp is said to grow best on fertile,

well drained, medium-heavy soils and especially well on silty loams, clay loams, and silty clays. It can grow on again wide variety of soil types. A pH of less than 5 has been reported unfavorable to Hemp Production.

Climatic Condition:Climatic Condition: Climatic Condition of the northern

plains are favorable to hemp production.

Agro climatic conditions of Assam and other Northeast region in India are very much suitable to grow Hemp in India.

Cultivation of HempSeed bed: It should be similar to

cereal bed and free from weeds. A stable seedbed made in march and cleaned before drilling during late April/early May is needed. Organic fertilizer need to be worked into the seed bed.

Hemp grown in green house.

Cultivation includes:Drilling: The seeds of Hemp are

sowed at an average of 30kg/acre. The seed must be drilled with a conventional 4inch cereal drill into moisture to the depth of 2 inch.

Rows of Hemp plants were about 7 inches apart with 2 inches distance between the plant in each row.

Harvesting procedure for Hemp Hemp harvesting

would be done early September.

Process includes:CuttingTurningBailingRetting

Harvesting ProcedureCutting: The crop

is cut with o mower or swather .

Turning: Turning is done with a rotary rake.

Baling: Turning in Bales with Baler.

Retting of HempRetting is done to separate bast

and Core fibers.It is carried out by immersing the

Hemp stalks in water in streams, pond, or artificial tanks for 8 days and second time little more days.

This process in complete when the bark, including the fiber, gets separated from stalks.

Hemp production in tonnes 2003–2004FAOSTAT (FAO)

 China 23000 79 % 24000 79 %

 France 4300 15 % 4300 14 %

 Chile 1250 4 % 1250 4 %

 Russia 200 1 % 300 1 %

 Turkey 150 1 % 150 < 1 %

 Ukraine 150 1 % 150 < 1 %

 Romania 100 < 1 % 100 < 1 %

 Hungary 40 < 1 % 40 < 1 %

 Poland 15 < 1 % 15 < 1 %

 Spain 8 < 1 % 8 < 1 %

 Serbia and Montenegro

2 < 1 % 2 < 1 %

Total 29215 100 % 30315 100 %

Morphological Properties Of Hemp Fiber.

Properties Hemp Core Hemp Core

Fiber Length(L)(mm) 0.5-0.6 5-55

Fiber Width (D) (µm) 15-25 16-50

Cell Wall Thickness , (µm)

3 14

Slenderness ratio (L/D)

27.5 1000

Chemical Analysis of Hemp:

Raw Material

Hemp Core

Hemp Bast

Cellulose %

36.3 71.7

Lignin % 27.1 4.0

Extractives %

1.2 0.9

Ash % 1.2 1.5

Pulping of Hemp.Following Types Of Pulping Can be

carried out with Hemp as a Raw material:-

Kraft PulpingSoda PulpingOrganosolve pulpingAlkaline thermomechenical PulpingChemithermomechenical Pulping

Pulping Kraft Pulping of certain fibers was

carried on at same pulping conditions and compared :

Cut Hemp stalk or Core fiber.Hemp bast fiber.Hemp wood retted.Hemp wood non retted.Birch.Pine .

Cut Hemp Stalk

Uncut & Cut Hemp Bast Fibers

Hemp Wood Retted

Hemp Wood Non Retted

Pulping process: Kraft Pulping

conditions: Bath Ratio 1:6 for

Bast fibers & 1:5 for Stalk fibers.

Temp. was raised to 165 °C in 90 min. & retained for 90 min.

Sulfidity was varied from 4-26%

Fig.1 Relationship between the Kappa number and the amount

of active alkali added in the process of the delignification of hemp raw materials and birch and

pine wood.

Fig.2 Comparison of pulp yields from industrial hemp raw

materials and conventional ones from wood at their different pulping levels.

Oxygen Delignification of Hemp

Oxygen Delignification of Hemp Bast Fiber as carried out at following conditions:

Oven dry fibers: 40gmConsistency: 8%Oxygen pressure: 6 Mpa at 100 °C0.1% MgSO4 dissolved in water.NaOH charged up to 2%Time 60 min.

Fig.3 Variations in the Kappa number of hemp bast fibers in the oxygen delignification process depending on the

amount of NaOH used.

Fig.4 Yield of hemp bast fibers in the process of their oxygen delignification compared with that in the process of

delignification with Kraft cooking liquor

Bleaching of HempBleaching of Hemp was carried out

using four stage (DEpAp) Procedure with Chlorine dioxide (D),Extraction (Ep), Acid (A), Peroxide (P) stages in sequence.

Procedure:In the first step, the pulp of 3.5%

consistency was acidified with dilute sulfuric acid. Sodium Chlorite solution was added in proportion to the kappa number of pulp.

The treated pulp was then kept in the water bath at a temperature of 50 °C for 60 min. Pulp was then washed carefully and used for the extraction stage.

In the extraction stage, consistency of 10 % was applied and NaOH (2 % of the O.D. basis) and peroxide (1 % of the O.D. basis) were used for extraction. This stage was retained for 90 minutes at a temperature of 80° C of water bath. After completion of desired time, pulp was washed with cold distilled water & used for the next step.

In the acid stage, at 3% consistency Pulp was acidified with the 1 % acid (O.D. basis) and retained for half an hour at a temperature of 50 °C. At the end of 30 minutes, pulp was washed with distilled water, and the last stage of peroxide was then carried out.

At 10% Pulp consistency the chemicals magnesium sulfate (0.25 %). DTPA (0.25 %), NaOH (2%) and peroxide (3 %) were added in Pulp and was then mixed well and retained in water bath at temp. of 80 °C for 4 hours.

At the end , pulp was washed with the distilled water to remove the chemicals used and then collected and weighed. Moisture content was measured to determine the yield of the bleached pulp.

Physical properties of pulp

Particulars Hemp Core pulp

Yield of unbleached pulp% 58

Yield of bleached pulp % 54.4

Brightness Of Bleached pulp %

80.2

CED Viscosity at 27°C (cp) 28.4

Initial Pulp Freeness (°SR) 16

Hand Sheet MakingHand sheets of 60 gsm were made from

both the bleached and unbleached pulp using British hand sheet former.

Hand sheets were dried at temperature of around 23 °C with relative humidity of

50 %. Hand sheets were tested and strength

properties were determined.

Physical strength properties of Paper sheet.

Strength properties

Unbleached Bleached

Bulk density (cc/g) 1.50 1.38Burst Index (kPa sq.m /g)

5.80 4.32

Tear Index (mN Sq.m /g)

11.77 8.37

Tensile Index (N m/g)

62.67 48.17

Folding endurance 320 125

°

Blending of hemp To evaluate the properties of paper from

the blending of pulp, the Bast fiber pulp and the core fiber pulp were blended at a ratio of 50:50.

Hand sheets were prepared and tested and the physical strength properties are presented in Table

Physical strength properties of Bleached Paper sheet made by

Blending.Strength properties Bleached Blended sheetBulk density (cc/g) 1.42Burst Index (kPa sq.m /g)

5.80

Tear Index (mN Sq.m /g)

9.85

Tensile Index (N m/g)

56.60

Folding endurance 190

Investment for hemp assuming high yield, small module scale & no recovery

system. Investment is calculated for 5000ton/year Pilot Plant.

Operation Annual Cost/Tone US$

Investment EstimateRefit 480Greenfield 600Operational CostFiber Crop 130Pulping Operation 400Total Cost 530NBSK* 950

Non Bleached Softwood Kraft pulp is used as a reference

Cannabis sativa. Height 2.5m

Problems encountered in use of Hemp fibers

Their seasonality Large storage area is

needed,Degradation of the fibers due

to improper care in storage. Requires high input and

costlier

ConclusionHemp can

positively seen as a raw material for paper making.

Cost (US$/tone)

process Hemp Hemp Softwood

Chemical Chemomechenical

Chemical

Pulping 2,100 530 820Paper making

1,900 800 800

Total Cost

4,000 1,330 1,620Cost of Chemical and Chemomechenical pulping process of Hemp Vs Chemical

processing of Softwood

Proximate Chemical Analysis Of Hemp

Particulars C. SativaSolubility %1. Cold water 4.22. Hot water 12.843. 1% NAOH 27.64. Alcohol Benzene 3.61Cellulose % 50.8Lignin % 4.8Ash % 4.5Silica % 0.75

Uses of hemp

• Hemp fibers are used in a wide range of products, including fabrics and textiles, yarns and raw or processed spun fibers, paper, carpeting, home furnishings, construction and insulation materials, auto parts, and composites. The interior stalk is used in various applications such as animal bedding, raw material inputs, low-quality papers, and composites. Hemp seed and oilcake are used in a range of foods and beverages, andcan be an alternative food protein source

• Hemp seed is also used forindustrial oils, cosmetics and personal care,

and pharmaceuticals, among other composites