UTIl.1ZAT1~N OF UNCURED RESIN IMPREGNATED PATER SCRA P
May 1944
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No. 1582
UNITED STATE$ ; DEPARTMENT OF AGRICULTUR E
FOREST SERVIC E
!FOREST PRODUCTS LABORATOR Y
L
Madison, Wisconsi n
In Cooperation with
Y
the University of
Wisoonsi .
fr,
UTILIZATION OF UNCURED RESIN IMPREGNATED PAPER SCRAP By MELBURN HEINIG, Assistant Chemis t
and F . A . SIMMONDS, Chemis t
Introductio n
In the commercial production of paper-base laminated plastic, substantial amounts of uncured resin-impregnated paper scrap in the form of trimming s
and rejects can be accumulated . The resin content of this material ma y
average 35 percent . It was believed that there would be an economic advantag e
of reclaiming the scrap provided it can be handled in the paper mill withou t
undue difficulty, that resin retention is high, and that a product of reason able quality can be obtained . This report presents the results of a limite d
number of trials made for obtaining information on the possibility of re claiming scrap resin-impregnated paper .
Summary of Conclusion s
The satisfactory properties of paper-base laminated plastics made fro m
papers containing reclaimed, uncured, resin-impregnated paper scrap rangin g
up to 100 percent, combined with the fact that no serious difficulty was en countered in reworking the scrap, indicate the practicability of the re-us e
of such material . In making paper commercially from this material, however ,
consideration should be given to the desirability of a closed white wate r
system in order to obviate any possible toxic effects of the effluent .
Scope of Wor k
Several furnishes containing various amounts of repulped, resin-impregnated paper scrap from a commercial source and new commercial sulfite pulp ,
with a maximum test of 100 percent of scrap, were made into paper on a Fourdrinier machine with ordinary operating technique . The paper containing onl y
scrap material was molded, both with and without prior addition of resin b y
impregnation . All other papers were impregnated with additional resin, prio r
to molding, with the amounts added estimated to yield a final total resi n
content of about 35 percent . Certain physical properties of the test panel s
were determined .
-This mimeograph is one of a series of progress reports prepared by th e
Forest Products Laboratory to further the Nations war effort . Result s
here reported are preliminary and may be revised as additional data be come available .
Restricted Mimeo . No . 1582
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H:
Furnish Preparation and Paper Makin g
The paper scrap had been made from black spruce unbleached Mitscherlic h
pulp and was impregnated with Bakelite resin BV-16526, A quantity of the scrap
was beaten with the roll at the bedplate setting for 25 minutes at a temperatur e
of about 20 0 C . and a consistence, based on fiber, of 4 percent . Pronounce d
foaming occurred at the start of beating, but this trouble was eliminated by th e
addition of kerosene in a volume equivalent to 1 .4 gallons per ton of Scrap .
Although at the end of the beating treatment email flakes of unfiberised pape r
still persisted, further processing would have resulted in a paper too low i n
absorbency for impregnating ,
The repulped scrap was used for making papers containing 100, 50, 25 ,
and 15 percent of scrap by adding a commercial unbleached Mitscherlich sulfit e
pulp made from black spruce . This pulp was a part of a shipment used in establishing a standard laminated paper plastic (papreg) at the U. S . Forest Product s
Laboratory in June 1943 . No trouble was encountered in running the foregoin g
furnishes on the paper machine .
As each run of paper was made, a sample of the wet web was taken off th e
first wet press . When the paper contained 100 percent scrap material a sampl e
of white water was also collected . The wet web samples and the white wate r
solids were then extracted with acetone, and the amounts soluble were considere d
as indications of the resin content .
Preparation and Testing of Panel s
Duplicate impregnation runs were made on each'paper using Bakelite resi n
3V-16626 . The aim was to add enough resin to bring the total amount to abou t
35 percent based on the resin-treated Sheet . Reference to table 1 reveals that ,
with the exception of one panel, which consisted of reclaimed scrap only, with out added resin, the total resin content ranged between 33 and 36 percent . The
total resin content values are based on the amount of resin added and the resi n
content of the paper prior to impregnation, which is determined by the percentag e
of acetone-soluble material of the wet web sample ,
i,lolding and testing conditions and results are given in table 1, Panel s
fabricated from paper impregnated in the first series of impregnation runs ;
identified as Nos, 2404-1, 2405-1, 2406-1, and 2407-1, were sent to the mil l
from which the scrap resin-impregnated paper was obtained . The test data show n
in table 1 for these panels are those reported by the mill . The second set o f
panels, identified as Nos . 2404, 2404-2, 2405-2, 2406-2, and 2407-2, wer e
molded from paper impregnated in the second series of impregnation runs an d
were tested at the U, S . Forest Products Laboratory . Because of the condition ,
and low content, of the resin in the paper used in molding panel No, 2404, th e
high pressure of 1,500 pounds per square inch was selected arbitrarily t o
assure lamination, The minimum, pressure necessary was not determined . The
addition, by impregnation, of 15 percent resin to this paper resulted in a material moldable at 250 pounds per square inch from which panels Nos . 2404-1 and
Restricted Mimeo . No, 1582
-2-
2404-2 were made . Test values-for the-Forest P'oduct s =. Laboratory June 194 3
standard papreg containing the same pulp used in the present study are include d
in table 1 for comparison .
Discussion of Results and'ConclLision s
T.he plastii ai; No.. .2404, .containing only . the reclaimed resin-impregnate d
scrap, with no . added .re.sin, and laminated at .- a pressure of 1,500 pounds pe r .
square .inch, although .low. .in aetual .•water'•resjstance, compares favorably in '
strength properties with those recently published for a commercial . high-strengt h
paper-base laminate? and also with those of the Forest Products Laborator y
Jape =1943 standard . The water absorption .of 4,2 percent observed for thi s
plastic is, . however, only-5 percent mor e , t, an. the- upper limit given #nor thO com mercial product . The addition of 15 percent resin (Nos . 2404-1 an d. .404-2 )
improved. water resistance markedly . The average water--re s.i•etance -of :2 .2 percent ;
appears especially :good..for the average specific gravity of .only 1 .32, as- .compared with water resistance and specific gravity values _of- .2 .4 and 1 .40, .! . :
respectively, of the June 1943 standard. which contained only virgin pulp-an d
resin .
The values for the properties of plastic No . 24CO and tlie aver,•age .value s for Nos . 2404-1 and 2404-2(100 percent scrap with added resin)
'. e-corp pare d
with the corresponding values for the June 1943 standard in table ? ., in.;whic h
the values for the standard papreg are taken as 100 for each property .
The results for the mixed furnishes, in comparison with the June 194 3
standard, show that when up to 50 percent or scrap was used 80 percent of the
modulus of elasticity in tension was retained with no sacrifice in the othe r
- . . '
physical properties that were evaluated .
, AltYaough the work reported here is limited., the results .indicate th e
practicability ., gf utilizing resin-impregnated p aper scrap .• in,laminates-,that ar e
not required to•meet high strength specifications in all_properties :- ,
_L T
?Plastics Catalogue, Plastics Catalogue Corporation, New York . 1944 . Page 768 .
-Since this work was . done, TAPPI Bulletin No, 26, February 19, 1944, mention s
the production of,paper base plastic containing reclaimed uncured resin impregnated fabric • sc _rap ._
.
Restricted ? imeo, No . 1582
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Table
scrap compared with those of the Forest Products LAbcratory ,
June 1943 standard for papreg'with the values of .. .the stem.dard ,papreg taken as 100 .
Plastic
No . 2404
Property
.;
: Average o f
: plastic Nos .
2404-1 an d
~_
:
' oion :
Te n
~, :
108
' . 91 '
^..:
102
75
Modulus of rupture
:
~--
96
Modulus of elasticity :
Ultimate
^,
Modulus of elasticity
Flexure :
80
Compression :
.
Yield at 0 .2 percent strain offset . :
104
:
102
:
:
` lOO
;
:
106
:
71
130
100
Mod~lu.o of elasticity
Modulus of rigidi`ty ,
^
I od impact :
FIatwlme
.
Edgewise
. .
Specific gravity
.
^ . .^^
.
`
Water absorption
Restricted Mimeo . Not 1582
:
101
:
..
:
:
175
:
:
^, . . .^,
^ .^
.~
91
.
82
,
.
87
94
'9 3
: