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Basic

Softwood comes from coniferous trees and has long fibers while hardwood comes from deciduous trees and has short fibers. Softwood has longer fibers, is stronger and rougher, and is used for products like paper bags and corrugated boxes. Hardwood has shorter fibers, is smoother, and is used for products like writing paper and tissue paper. Examples of softwood include pine, fir and spruce while examples of hardwood include oak and maple. Hardwood has a higher density than softwood, which impacts paper properties.

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152 views3 pages

Basic

Softwood comes from coniferous trees and has long fibers while hardwood comes from deciduous trees and has short fibers. Softwood has longer fibers, is stronger and rougher, and is used for products like paper bags and corrugated boxes. Hardwood has shorter fibers, is smoother, and is used for products like writing paper and tissue paper. Examples of softwood include pine, fir and spruce while examples of hardwood include oak and maple. Hardwood has a higher density than softwood, which impacts paper properties.

Uploaded by

vivek singh
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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Raw material:

Softwood : these are the plant with needle shape leaves and having
long fiber.(Gymnosperms i.e naked seed)

Hardwood: : these are the plant with broad shape leaves and having
short fiber.(Angiosperms i.e seed inside the fruit)

Softwood Hardwood
Fiber length Long fiber (3-6mm) Short fiber (1mm)
Type of tree These wood comes from These wood comes from
coniferous trees deciduous trees
Feature Stronger and rougher Smoother
Typical product Paper bags and corrugated Writing paper and tissue
box paper
Example Pine, redwood, fir, spruce Oak ,maples
Composition of
wood
Cellulose 42%±2 45%±2
Lignin 28±3% 20±3%
Extractives 3±2% 5±2%
Hemi-cellulose 30-32% 18-25%

How density of wood is related paper

Paper yield per unit volume is proportional to density and high density
wood pulp has slower beating rate, bigger bulk, and tensile strength.
Hardwood has the higher density than softwood.

1. Softwood pulp paper has good flexibility ,high folding strength


,good tensile strength and printability .ex text paper, coated
paper, map paper, offset paper ,technical papers.
2. Hard wood pulp paper is loose with strong absorptivity and high
opaqueness, high thickness ,high stiffness.
3. Softwood pulp is more expensive than hardwood pulp .

Cellulose : cellulose is complex carbohydrate or polysaccharides’


consisting of 3000 or more glucose unit.

Or

Cellulose is linear chains of D-glucose linked by ß-1,4-glycosidic


bonds .
Hollo-cellulose : is a term for the entire carbohydrate fraction of
wood which includes cellulose and hemicelluloses.
α – cellulose : - indicate un-degraded higher molecular weight
cellulose .
β-cellulose :- it indicate degraded cellulose.
γ-cellulose :- it consist of mainly cellulose.
Pentosan:- softwood contain 7-10% and hardwood contain 19-
25%. Pentosan content in the pulp indicate the extent of loss of
hemicelluloses during pulping and bleaching .
Hemicellulose :- it is group of complex heteropolysaccharides
made of various sugars( D-xylose ,D- glucose etc).it having DP
around 200.
Hemicelluloses increases the strength of paper (
especially tensile, burst , and fold) and the pulp yield but are not
desired in dissolving pulp

Lignin: - lignin is complex and high molecular weight polymer built


upon phenyl propane unit and composed of carbon ,hydrogen
,oxygen.
Extractive :- these are materials in wood that are soluble in
neutral organic solvents. Example terpenes, fatty acids.
Non woody fibers :-

source cellulose lignin Extractive Hemicellulose


bagasse 40 20 10 30
wheat 30 15 5 50
jute 71 13 2 14
hemp 70 6 2 22

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