Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
WO 96/10054 PCT/US95/12186
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1_ F,'_Pld of theInvention
The present invention is directed to an improved
process for carpet reclamation and more particularly,
the process is directed to the use of an agent for
chemically softening or dissolving binder material con-
ventionally associated with carpet in order to expedite
and simplify the reclamation process.
2. nescript,'_on of the Prior Art
Carpet reclamation processes have been previously
proposed in the art and are exemplified by the process
disclosed in U.S. Patent No. 5,230,473, issued to
Hagguist et al., July 27, 1993.
In the Hagguist et al. method, apart from intro-
ductory steps which involve screening the carpet, and
preliminary loop cutting and other processing, the
removal of the secondary backing involves a whole
series of steps. This additionally is the situation
when the binder material is to be removed from the
primary backing.
In greater detail and with respect to the removal
of the secondary backing from the carpet, the carpet
must be initially exposed to fluids under pressure for
loosening and debonding the latex binder from the sec-
ondary backing. The next step includes passing the
remaining material. onto a further processing stage
where the secondary backing is mechanically treated
with~rotating mechanical impingement devices on both
sides of the carpet. It is the mechanical arrangement
that results in the removal of the secondary backing.
At this time, the bindersystem is still substantially
intact.
In order to remove the binder material, the re-
maining carpet structure must be passed to yet another
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stage where there is included a plurality of rotating
brushes as well as rotating high pressure nozzle heads.
This, as indicated by the patentees, results in the
gradual loosening and removal of the binder system from
the primary backing.
In view of the teachings of this reference, it
is clear that the method is dependent on the use of
mechanical means for the removal of not only the sec-
ondary backing, but further the removal of the latex
binder conventionally positioned between the secondary
backing and the primary backing.
The Hagguist et al. process also suffers the draw-
backs common to all multiple step processes, including
increased production time and cost, the use of a great-
er number of wing parts, the potential requirement
for a larger labor force and difficulty in efficiently
operating at a commercial level wherein, for example,
millions of, square meters of carpet may be processed.
In view of what has been proposed in the prior art
set forth above, there clearly exists a need for a high
efficiency method of reclaiming base components of a
carpet quickly and without the use of toxic contami-
nants or multiple stage processes.
BRz"'~ S'LJN~.~3RY OF THE nQVENTION
The present invention satisfies the above needs
and achieves the results and benefits set forth below
by providing a process for reclaiming carpet compo-
nents, the carpet including backing material, binder
material and carpet pile, the process comprising the
steps of: contacting the carpet with a composition
including a chemical softening agent (as defined below) '
for the binder and separating the pile from the
backing.
The amount of chemical softening agent in the
composition and the conditions for the contacting step,
WO 96110054 ~ PCT/US95/12186
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for example temperature and time, may be selected to
either substantially dissolve the binder or soften the
binder.
The process and device of the present invention
permits the reuse and recycle of the pile material into
critical end uses requiring a high degree of product
purity such as, for example, carpet fibers, plastic
pellets and other materials. Once the contacting step
is complete, the backings may be separated from each
other by making use of mechanical means, fluid means
including air and liquid flow, vacuum means or by
manual means.
According to yet another aspect of one embodiment
of the present invention there is provided a system
for reclaiming carpet components, the carpet including
backing material, binding material and carpet pile, the
system including: advancing means for advancing the
carpet to a solvent application means; solvent applica-
tion means for applying solvent to the carpet to dis-
solve the binder material; and collection means for
collecting separated backing material and carpet pile.
It will be readily appreciated that the process
as set forth herein is clearly applicable to all carpet
types including, for example, standard carpet with
styrene butadiene rubber latex binders and primary and
secondary backings, and those with foam layers, includ-
ing urethanes.
B~TEF DESCRIPTIcmr OF' T,ElE DRAW~1C~
Having thus generally described the invention,
reference will be made below to the accompanying draw-
ings illustrating preferred embodiments and in which:
Figures 1 and 2 illustrate various types of
carpeting in cross-section; and
Figure 3 is a schematic illustration of the
process according to one embodiment of the present
invention.
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DETAILED DESCRIY1.1C3N of TFiE PREFERRED EMBODI~TS
Referring now to the drawings, Figures 1 and 2
illustrate cross-sectional views of typical carpet .
varieties which are processable according to the pres-
s ent invention. In Figure 1, the carpet 10 includes a
primary backing 12 within which is disposed carpet pile
14. The carpet pile 14 is fixedly secured to backing
12 with binder 16, typically a latex binder. Prefera-
bly, a secondary backing 18 is additionally provided
and is secured to primary backing 12 by binder 16.
Figure 2 illustrates a second carpet type wherein
the binder material 16 comprises a foam material 20 and
the carpet 10 does not include a secondary backing.
Ti~hile these carpet types are shown as exemplary of
carpets processable according to the present invention,
it will be appreciated by those skilled in the art that
other types of carpeting may also be processed accord-
ing to the present invention.
Prior to the performance of the process of the
present invention, the carpet may be screened for pro-
cessing suitability. The use of visual inspection,
metal detectors, etc., may be employed to this end.
Further, the carpet may be cleaned or preconditioned
with, for example, a surface active agent or other
compounds) to enhance the processing thereof.
The process of the present invention includes
contacting the carpet with a composition which includes
a chemical softening agent for the binder. 'I"he te~tn
"chemical softening agent", as utilized herein, is
defined as any agent capable under specified conditions
of softening or dissolving a material, for example a
binder material, via chemical reaction or interaction
therewith. The specific chemical softening agent will
therefore be selected based on the type and nature of
the binder used in the carpet. The teen "composition"
is defined herein to include, without limitation, mix-
tures, solutions, emulsions, dispersions and the like.
WO 96/10054 PCT/US95/12186
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The chemical softening agent preferably is non-
toxic and environmentally friendly. A preferred chemi-
cal softening agent includes at least one dimethyl
ester. Dimethyl adipate, dimethyl glutamate, dimethyl
succinate and mixtures thereof are especially pre-
ferred. Particularly preferred chemical softening
agents are dimethyl succinate and a mixture of dimethyl
adipate and dimethyl glutarate. Suitable dimethyl es-
ters are commercially available from Monsanto Company
under the trade name SAN1~SOL~.
Suitable compositions include aqueous or non-
aqueous compositions of the chemical softening agent.
In order to further enhance the dissolution or soften-
ing of the binder, additional chemicals may be added to
the composition including, for exar~le, surface active
agents to enhance the wettability of the backing mate-
rial of the carpet. In addition, thickeners may be
added to control the flow and adhesive properties of
the composition. A particularly useful thickener is
commercially available from B. F. Goodrich under the
trade name CARBOPOL~.
A preferred composition includes at least one
dimethyl ester and water, most preferably in a weight
ratio of about 1:1.
The concentration of chemical softening agent in
the composition will vary greatly depending on the type
of carpet and the conditions utilized in the contacting
step such as, for example, time and temperature. Pre-
ferred chemical softening agent amounts are from at
least about 10% by weight based on the total weight of
the composition.
The contacting step may be performed by any meth-
od, including, for example, immersing the carpet in the
' composition, applying the composition to the pile or
applying the composition to the backing. Preferably,
the contacting step is performed in the presence of a
surface active agent. The surface active agent may be
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added to the composition which contacts the carpet. or
it may be pre-applied to the carpet prior to the con-
tacting step. Suitable surface active agents include,
for example, anionic and nonionic surfactants.
The condition for the contacting step will vary
greatly depending on, for example, the carpet type,
type and concentration of chemical softening agent, and
the like. Contact time will generally extend at least
5 seconds while the contact temperature may range from
ambient temperatures to just below the boiling point of
the composition. In a preferred embodiment wherein at
least one dimethyl ester is utilized as the chemical
softening agent, the contacting step is performed at a
temperature of at least 20°C, more preferably at least
35°C.
Preferably, the concentration of solvent is
selected and the contacting step is perfornled under
conditions sufficient to reduce the amount of force
required to remove a tuft from the carpet by at least
50% according to the test set forth in the examples
below.
In a first particularly preferred embodiment, the
concentration of chemical softening agent is selected
and the contacting step is performed under conditions
sufficient to substantially dissolve the binder in the
agent. Most preferably, the pile removed after the
contacting step will therefore be substantially free
from binder as the binder is dissolved in the agent.
The process may further include removing the dissolved
binder from the composition and recovery of the chemi-
cal softening agent.
In a second preferred embodiment, the concentra-
tion of chemical softening agent is selected and the
contacting step is performed under conditions suffi- '
cient to soften the binder. In this embodiment, the
WO 96/10054 PCT/US95/12186
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process of the present invention optionally includes
removing binder from the pile after pile is separated
from the backing.
Any residual composition present on the individual
base components (pile and/or backing[s]) of the carpet
may be removed by simply washing the components and
this may additionally include pressurized washing mak-
ing use of a suitable washing agent.
Turning to Figure 3, which illustrates a schematic
illustration of a device suitable for practicing the
process of the invention for processing the carpet of
FIG 1, a first roller 30 advances the carpet material
to a first pair of liquid nip rollers 32 and 34. First
set of rollers 32 and 34 include the composition for
application onto the secondary backing 18 of the carpet
10. The composition is preferably heated such that the
contacting step is conducted at a temperature of at
least 35°C. A second set of rollers 36 and 38 further
apply additional amount of the composition through the
secondary backing into the binder material of the
carpet.
The carpet is then passed between two star wheels
40 and 42 which mechanically loosen the secondary back-
ing from the carpet passing therethrough. At this
point, the secondary backing is effectively removed
from the carpet and to this end, an abrasive roll 44 is
provided and further acts on a smooth roll 46 to remove
the secondary backing from the carpet. The removed
secondary backing may be passed ~n through rollers 48
and 50 to a high pressure wash, globally denoted by
numeral 52, optionally dried by pressure rollers 54 and
56 and collected on a spool 58 for subsequent usage.
Once the secondary backing 18 has been completely
removed, the primary backing 12, together with the pile
14 and binder 16, are further treated with the solvent
using a nip roller arrangement 60 and 62 in a similar
manner as set forth with respect to nips 32 and 34.
WO 96/10054 PCT/US95/12186
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After a suitable dwell time, the remaining material is
subjected to a high pressure water wash at 64 in order
to remove any residual binder from the primary baclting
along with any remaining solvent. After entering the
washing cycle64, the primary backing and carpet pile
is then dried in a drying cycle at 66 using any suit-
able means for effectively drying, e.g. forced hot air.
In order to remove the carpet pile 14 from the
primary backing 12, once dried, the primary backing and
carpet pile are passed into contact over a source of
vacuum. In the embodiment shown, this is an inverted
vacuum plate 68 which pulls the carpet pile 14 of the
primary backing 12 for subsequent collection as gener-
ally indicated by the arrow 70 in Figure 3. Any re-
maining particles of binder 16 are then dropped into a
collection unit (not shown). 'Ihe separated primary
backing 12 is then optionally washed and passed on to a
collection spool, the latter steps not being schemati-
cally illustrated in Figure 3.
As further steps, the solvent may be applied
pressurably to the carpet. Further, the carpet may be
passed through the system a second time, when required.
In addition to the above, the spent solvent may be
reused by recycling the same subsequent to filtering
the spent solution. Further, the solvent may be puri-
fied by distillation or other well known chemical puri-
fication techniques.
Other solvents may be combined with the dissolving
solvent to enhance dissolution or softening of the
binder.
'rhe following examples, while not intended to
limit the scope of the present invention, serve to
further illustrate and describe its benefits.
WO 96/10054 PCT/US95/12186
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ales 1-9
I . s i t i on prP~ ra fi i nn
Compositions for use in the process of the present
invention were fozmu.lated according to the specifica-
tions set forth in Table 1 below.
Table 1
Ca~ositia~ns
Item Chemical Softening Agent Water
No. Wt % of Composition Wt o of Composition
1 dimethyl adipate, 1000 0o
2 dimethyl adipate, 500 500
3 dimethyl succinate, 100% 0o
4 dimethyl succinate, 50% 50%
5 dimethyl glutarate, 100a 0o
6 dimethyl glutarate, 500 500
dimethyl adipate, 23-270
7 dimethyl glutarate, 72-76o po
dimethyl adipate, 12-140
8 dimethyl glutamate, 36-380 500
WO 96/10054 ~ PCT/US95112186
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II. ~'ar~t- Treatment Procedure
2-inch (5.08 cm) by 2-inch (5.08 cm) samples of a
conventional carpet construction having tufts, a prima-
ry backing, a styrene-butadiene rubber latex adhesive
and a secondary backing were partially immersed in one -
of the composition items in Table 1 at ambient tempera-
ture. For each composition item, the composition
amounts tested were 5 ml, 7 ml and 10 ml. For each
amount tested, the immersion times tested were 5 min-
utes, 60 minutes and 18 hours. Control samples were
left untreated.
III. 'T'~?ft Removal Test
The samples, including the controls, were then
tested to determine the force required to remove a tuft
from the sample. Each sample was immobilized and any
excess composition removed. The tip of an individual
tuft was then grasped with a clamp and pulled on until
it was removed from the carpet sample without breaking.
The clamp was connected to a conventional INSTRON~
testing device which measured the maximum pulling force
exerted on the tuft by the clamp during its removal
from the carpet sample. Three individual tufts from
each sample were tested in this manner and an arithme-
tic average force (F) for each sample was calculated.
A force reduction percentage versus the control was
also calculated as
%nF = [ (F~~1-F) / F~~,1] x 100%
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The results are set forth below in Table 2,
with item numbers corresponding to those provided
, in Table 1.
~ Table 2
Force Reduction o
Item No . ( o a F from Control
)
1 67.8
75.0
57.1
4 78.6
5 57.1
78.6
7 71.4
8 78.6
Control
(Untreated Samples) 0
As shown above, the process of the present inven-
tion reduced the force required for tuft removal at
least 50o and for some items as much as 75a or more.
PCT/LT595/12186
WO 96/10054
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,ales 10-14
For exatt~ples 10-14, compositional items 2, 4, 6,
and 8 from Table 1 were utilized in test procedures
identical to those set forth i~ Examples 1-9 except
that the treatment of the carpet sample was conducted
at a temperature of 50°C. The results are set forth
below in Table 3.
Table 3
Test Item Composition % nF from
No. Item No. Control
10 2 82.1
11 4 89.3
12 6 85.7
13 8 78.6
Control
14 (Untreated Samples) 0
As shown above, the presence of heat in the con-
tacting step of the process of the present invention
further reduces the force required for tuft removal.
Although embodiments of the invention have been
described in detail herein, it will be appreciated by
those skilled in the art that n~~merous modifications
may be made to the invention without departing from the
intended scope of the invention.
