AGRICULTURE ROOM
SEMICHEMICAL AND SULFITE PULPING EXPERIMENTS AND
PRODUCTION OF SEMICHEMICAL CORRUGATED BOARD
FROM RED GUM (LIOUIDAMPAR STYRACIFLUA)
August 1939
UNITED STATES DEPARTMENT OF AGRICULTURE
FOREST SERVICE
LFOREST —PRODUCTS LABORATORY
Madison, Wisconsin
L-
In Cooperation with the University of Wisconsin
SEMICEEMIC AL AND SULFITE PULPING EXPERIMENTS AND PRODUCTION OF SEMICHEMICAL CORRUGATED BOARD FROM RED GUM (LIQUIDAMBAR STYRACIFLUA)
By
G. H. CHIDESTER, Senior Engineer,
and
J. N. McGOVERN, Assistant Technologist
Large quantities of red gum, among other hardwoods, are available
in pulpwood size in various parts of the South. A. market for rid gum pulpwood would provide an outlet for thinnings and cleanings to supplement its
present use for lumber and be of material aid in improving forestry practice
in many of these areas.
The experiments reported here were made to determine the suitability of red gum for the manufacture of corrugating board, a high tonnage
product in growing demand. Also, preliminary trials were made to furnish
information on the suitability of the wood for sulphite pulp. For corrugating board the semichemical pulping process, which has given a high
yield of pulp suitable for this purpose from other hardwoods with a consequently low cost, was used.
WOOD USED
The sample of red gum (Liouidambax styraciflua) consisting of
about 5 cords, supplied through the courtesy of the Arkansas State Forest
Service, was cut in Prairie County, Arkansas. The stand was second growth
and contained about 200 trees per acre, averaging 10 inches d.b.h. The
properties reporte gl for the wood are given in tables 1, 2, and 3. The
evaluation of the wood showed no abnormalities except for irregularity of
the heartwood. The chemical analysis shows the hip pentosan content
typical of hardwoods. attermeisterg reports a fiber length of 1.55 mm.
and a diameter of 0.031 mm. for red gum.
1
-Schafer,
E. R. and Pew, J. C. Physical and Chemical Properties of Red Gum
(Libuidaribar styraciflua) Pulpwood,. Shipment No.. 150S. U. S.. Forest
Products Laboratory report, Project L-168-5, Problem D-172.
2
-Sutermeister, Edwtn. Chemistry of Pulp and Paper Making.,
R1415
In contrast to blackjack oak which was investigated similarly,"
red gum had a higher cellulose content and lower extractive contents. In
spite of having considerably less bark and larger volume of solid wood per
cord, its lower density resulted in a somewhat lower weight of oven-dry wood
per cord. Although the color of the red gum heartwood was dark as in the
oak, the sapwood was considerably lighter than the oak. Because of the
light color of the sapwood and the much smaller volume of heartwood, the
red gum would be expected to give considerably lighter-colored semichemical
pulp than the oak.
=IC REMIC AL PULPING
Semichemical pulping studies were made in a steam-jacketed,
stainless alloy-lined autoclave to determine the conditions suitable for a
pulp yield range ef about 70 to 80 percent. Larger scale digestions were
then made in a 69-cubic-foot rotary digester to give pulps representative of
those obtainable in high and low yield for the preparation of nine-point
corrugating beard, The results of the digestions are given in table 4.
The first digestion of the autoclave series gave a relatively.
low yield for this type of product (68.1 percent). In the following
digestions the concentration of chemicals in the impregnating liquor was
reduced and shorter times were used for both penetration and cooking to give
higher yields. The highest yield obtained in the series was 76.9 percent.
The results indicated that red gum was more readily reduced by the
semichemical process than was blackjack oak in previous trials, 3 in that
less concentrated liquor and less drastic conditions were necessary to
produce similar yields.
Very little difference was indicated in the strength properties
of the pulps obtained in the different yields. The tearing strength at the
lower freeness was slightly lower for the highest yield pulp and the beating
time was longer. The strength values of all of the red gum pulps were about
double those obtained from blackjack oak, and the color, in some instances,
much lighter.
The two larger-scale digestions gave pulp yields of 73.8 and
79.2 percent. The higher yield pulp developed slightly lower bursting and
tearing strengths and required a longer time for processing than the lower
yield pulp. The color of the higher yield pulp was considerably lighter
than that of the other, probably owing to the fact that the digestion of
the lower yield pulp was carried more nearly to exhaustion of the chemicals
in the liquor.
"VbGovern, J. N. and Chidester, G. H. Semichemical and Sulfite Pulping
Experiments and Production of Semichemical Corrugating Boards from
Blackjack Oak. Project L-168-5, Problem B-189.
R1415
-2-
44P4RATION OF CORRUGATING BOARD
Three machine runs were made on the two pulps from the larger=
scale digestions to make nine-point corrugating board:. The differences in
the strength of the boards obtained from the two pulps, were again very
small; the tearing strength. obtained from the lower yield pulp was slightly
higher than that obtained from the other (table 5).
The strength of the boards was superior to that of blackjack oak
boards, but may have been partly due to differences in processing. The
strength was much superior to most commercial corrugating boards and excellent products were obtained in corrugating trials.
SULFITZ PULPING
Two sulfite digestions of red gam were made, one under conditions
which would be considered representative of commercial conditions and the
other at comparatively high temperatures in .a short time (table 6). The
total cooking times were 10.1 and S.3 hburs, respectively. The results
showed red gwm to be readily reducible by the sulfite,process. The pulps
were comparatively dark colored, but required a comparatively small amount
of bleach to produce a standard whiteness. The strength was characteristically
low.The results, except for the darker color of the unbleached pulps,
were quite similar to. thee° obtained in pulping other hardwoods, such as
black gum' and aspen, by the sulfite process.
R14f5
Table 1.--Phy sical characteristics of red gum pulpwood, shipment 1508
Weight of cord: (Basis 4-foot unbarked logs, 128 cubic feet
Unbarked, as received. Barked, as received Barked, oven-dry (Weight barked x percentage nonvolatile)
(Solid volume x density) Solid-volume of wood in cord as received Number of logs in cord Straightness (basis number logs in cord) -Nearly straight, less than a deviation of 0.5 inch Crooked, greater than a deviation of 0.5 inch Average deviation of crooked logs from straight Logs with large protruding knots or bumps -(Basis total in cord) .
Knots, average number per log (Basis sample logs) -Small Medium Large Loss through barking -In weight (Basis unbarked logs, as received) (Basis unbarked discs, oven-dry) Specific gravity -(Basis discs i • oven-dry weight, green volume).. (Basis discs, oven-dry weight, oven-dry volume) ...... Density
(Basis discs, oven-dry weight per cu.ft. green volume) Nonvolatile at 105° C. (Basis discs as received) -Uhbarked Barked 4..4 Bark Diameter of barked logs -Maximum ,
Minimum Average Volume of heartwood (Basis discs) Age (Average of discs) Rate of growth, average per inch -R1415
gross volume)
5,670 pounds
4,880 pounds
2,320 pounds
2,340 pounds
80.9 cu.ft.
81
56 percent
44 percent
0.8 inch
2.5 percent
7.6
1.4
.5
13.9 percent
16.0 percent
0.462
.537
28.8 pounds
48.7 percent
47.4 percent
57.8 percent
10.3 inches
4.0 inches
6.6 inches
6.2 percent
34.5 years
10.3 rings
Table 2.--Color anal y sis of red Aum_pulpwoodi. shipment 1908
:
Ives readings : Color analysis from Ives readings
:
Material :
:
:
: Red : Green : Blue : White
:
:
:
•
:
:
:
:
:
Percent
Sapwood...: 78 :
:
:
Heartwood.: 36 :
Table 3.-
65
:Percent:
:Percent:
: Percent
•
•
•
55 :
.
:
23 : .28 :
•
: Primary hue : Secondary hue
:
: Tint : Lumi- : Tint : Lumi:
:nosity : : nosity
.
.
•
18 :Orange : 6.4 :Red
.
21
3 aical
Cellulose Alpha-cellulose Lignin Total pentosans Pentosans in cellulose.. Solubility in -Hot 1 percent sodium hydroxide solution Hot water .Alcohol-benzene Ether 81415
•
55 :Orange : 8.3 :Yellow :
'
:
3.2
.6
wood shipment 1508
Oeoe o 60.5
44.5
21.4
20.7
22.6
percent
percent
percent
percent
percent
12.0 percent
2.5 percent
2.0 percent
.5 percent
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Table 5.--Prop erties of red gum corrugating boards
Kind
Physical properties
Machine: Diges-:
of
:
run : tion : proc- :
:Bursting:Tearing :Tensile : Solid :
:
: essing :Caliper:strength:strength:strength: frac- :Stretch
.
:
: tion
No. : No. : :Points :Pt./lb./:Gm./lb./:
Lb./so. :
:
:
•
: ream
: ream
: la.
:
:
:
:
..
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Ream size -- 25 x 40 - 500
'•
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.
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:
:
:
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.:
.:
1413 : 2498-N: and
: 9.50 :
.52 .. 1.07 : 4,570
.
: Jordan :
:
:
:
:
.
.
:Beater .:
:
1414 : 2496-N: and : 8.12 :
.48 : 1.28 : 4,500
:
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;
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81 4 15
:
..
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:
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R1415