Composite adhesive webs and their production

Disclosed is a composite adhesive web and a process for the production of such a web. The thermally adhesive web of the invention is comprised of a composite of randomly arranged thermoplastic filaments or, parallel thermoplastic filaments interconnected by randomly arranged thermoplastic fibers or filaments, and a fibrous thermal adhesive nonwoven sheet containing thermoplastic fibers, preferably low melting thermally adhesive fibers.

BACKGROUND OF THE INVENTION 
The present invention is in a composite adhesive web and a process for its 
production. 
British Pat. No. 1,117,751 describes the reproduction of a thermally 
adhesive web from a tissue of randomly arranged thermoplastic filaments. 
The webs are widely used in combination with nonwoven materials as 
stiffening interlinings, which can be ironed onto materials to be 
stiffened, i.e., garment parts. 
In the method of the British Specification, thermoplastic material is 
continuously extruded and collected as a web on a continuously moving 
sheet. The moving sheet is preferably a nonwoven. The filaments in the web 
are caused or allowed to fuse to one another and to the sheet to form a 
fusible interlining for various apparel applications. 
The thermoplastic polymers can be extruded and collected as a web on a 
continuously moving sheet, where the filaments are caused or allowed to 
fuse to one another, but not to the sheet. In this case, the tissue of the 
randomly arranged thermoplastic filaments bonded to one another can easily 
be removed from the carrying sheet to form a thermally adhesive web. 
The extrusion process to form a web from randomly arranged thermoplastic 
filaments can be as described in British Pat. No. 1,117,751 or in a 
meltblown process as described in U.S. Pat. No. 3,825,380. 
The webs of the prior art are useful as thermal adhesives in various 
textile interlining and other applications. The webs are lightweight 
typically weighing from 20 to 80 g/sq.m. Because the webs are thin and 
light, they have a rather low tensile strength. Heavier webs tend to be 
firm but brittle. 
It is often desired to use the web in form of a tape. Typically the minimum 
width is 10-13 mm. However, because of the low tensile strength and/or 
brittleness, and because of the difficulties in handling the tape, 
especially using high speed mechanical handling apparatus, it is necessary 
to insure that the tape has sufficient tensile strength. If the tape does 
not have sufficient strength it will break during handling. Despite the 
above and other difficulties, thermally adhesive webs have been widely 
used and have gained recognition as important materials. However, the 
above-described disadvantages have imposed some constraints on their 
application. 
A thermal adhesive web of improved tensile properties can be formed 
according to U.S. Pat. No. 4,490,427 which discloses a web wherein 
parallel filaments of thermally adhesive polymers are bonded to, and 
interconnected by, randomly arranged polymeric fibers. The use of parallel 
arranged thermoplastic filaments improves the tensile strength of such a 
material, but still not to the desired tensile strength. 
U.S. Pat. No. 4,440,819 discloses multidirectional fiber arrays wherein 
graphite, glass or other fibers in substantially unidirectional arrays are 
interconnected with polymeric fibers. Interconnected material may 
subsequently be layered, impregnated with resin and laminated to yield 
unidirectional fibers/resins/polymer fiber composites. 
However, it has been found that thermally adhesive webs of the prior art 
lack the desired tensile - elongation properties especially at weights 
over 40 g/sq.m. 
SUMMARY OF THE INVENTION 
The present invention is in a composite adhesive web and a process for the 
production of such a web. The thermally adhesive web of the invention is 
comprised of a composite of randomly arranged thermoplastic filaments or, 
parallel thermoplastic filaments interconnected by randomly arranged 
thermoplastic filaments, and a fibrous thermal adhesive nonwoven sheet 
containing thermoplastic fibers, preferably low melting thermally adhesive 
fibers. This fibrous thermal adhesive nonwoven sheet may comprise 10-90% 
of thermoplastic fibers and 90-10% of other fibers. The fibers therein are 
interconnected by means of heat and/or pressure, or dispersed polymeric 
binders or a combination of these. The thermoplastic fibers may be 
comprised of co-, ter-, or higher polyester or polyamides or PVC, i.e., 
such as a terpolymer of nylon 6, 66, and 12. The meltpoint range of the 
thermoplastic fibers is in the range of 75.degree.-140.degree. C. The 
thermal adhesive nonwoven sheet may comprise about 50-60% of the weight of 
the composite web and the thermoplastic fibers and filaments of 40-98% of 
the composite web. The composite has a weight of from 10 g/sq.m to 180 
g/sq.m and may be in the form of a tape. 
In an additional aspect of the invention, there is provided a novel and 
improved nonwoven sheet having inherent adhesive properties. 
The various features of novelty which characterize the invention are 
pointed out with particularity in the claims annexed to and forming a part 
of this specification. For a better understanding of the invention, its 
operating advantages and specific objects obtained by its use, reference 
should be had to the accompanying drawings and descriptive matter in which 
there is illustrated and described a preferred embodiment of the 
invention.

DESCRIPTION OF A PREFERRED EMBODIMENT 
Composite webs according to the present invention are comprised 
substantially of a composite of randomly arranged thermoplastic filaments, 
or parallel thermoplastic filaments interconnected by randomly arranged 
thermoplastic filaments, and a fibrous thermal adhesive nonwoven sheet, 
containing thermoplastic fibers. 
The thermoplastic fibers may be comprised of co-, ter-, or higher 
polyesters, polyamides or PVC, i.e., such as a terpolymer of nylon 6, 66 
and 12. The melt point range of the thermoplastic fibers is in the range 
of 75.degree.-140.degree. C. 
Natural or man-made fibers used in textile applications have by the 
polymerchemical nature of the polymers, and by the manner of 
manufacturing, a much higher level of tenacity than the thermoplastic 
filaments used in thermally adhesive webs. The typical tensile strength of 
man-made staple fibers are given in Chart No. 1 (from E. Wagner: Die 
Textilen Rohstoffe, DFV Frankfurt/M 1981): 
______________________________________ 
Chart No. 1 
Tensile Strength 
cN*/dtex 
p**/den 
______________________________________ 
PET - staple fibers 
2.0-6.5 2.3-7.4 
Nylon (.6,) 
staple fibers 3.5-5.0 4.0-5.7 
Rayon (B-type,HT) 
staple fibers 1.8-3.4 2.0-3.9 
______________________________________ 
*cN = Centi Newton (.01N) 
**p = pond = 0.9807 cN; 1 kp = 1000 p 
Polymeric fibers in thermally adhesive webs, depending on their 
polymerchemical properties (i.e., lower crystallinity, less draw 
orientation), normally have much lower tenacity than the above-mentioned 
textile fibers. 
______________________________________ 
Chart No. 2 
Tensile Strength 
cN/dtex 
p/den 
______________________________________ 
Co-PES filaments in 
thermally adhesive webs 
0.05-0.1 0.06-0.11 
Co-or Ter-PA filaments 
in thermally adhesive webs 
0.02-0.15 
0.02-0.17 
______________________________________ 
In nonwoven applications natural or man-made fibers, regardless of the 
fiber length, may be manufactured in the form of fibrous sheets with 
randomly arranged or to some extent oriented fibers, which may be 
interconnected by means of heat and/or pressure using high melting fibers 
(150.degree.-250.degree. C.) or dispersed polymeric binders or a 
combination of these procedures. These nonwoven fleeces are widely used in 
textile and many other applications. These nonwovens by the nature of the 
comprising components do not act as a thermally activated adhesive. 
In this invention, natural or man-made fibers and thermally adhesive 
polymeric fibers, regardless of the length of these fibers, are 
manufactured in the form of fibrous sheets with randomly arranged or to 
some extent oriented fibers, which may be interconnected by means of heat 
and/or pressure, or dispersed polymeric binders, or a combination of these 
procedures. The manufactured fibrous sheets comprise 10-90% thermal 
adhesive polymeric fibers, preferably 30-70% and 90-10% other fibers. The 
thermally adhesive polymeric fibers may be comprised of co-, ter- or 
higher polyesters or polyamides or PVC, i.e., terpolymer of Nylon 6, 66 
and 12. The meltrange of the thermal adhesive polymeric fibers is 
preferably 75.degree.-140.degree. C. or higher, but below the melting 
range of the contained other fibers. The dispersed polymer binder, 
preferably thermoplastic resin of a type such as PVAc, PVC, PES etc., if 
used to interconnect the thermally adhesive and other polymeric fibers, 
may also have thermal adhesive properties. 
The arrangement of the thermal adhesive fibers and the other fibers may be 
random or to some extent oriented and may be manufactured on carding 
equipment with a subsequent interconnecting step. 
The fibrous thermal adhesive sheet should be manufactured to have an open 
structure. The openings should be randomly arranged and are preferably 
0.5-5 mm wide and 1-50 mm long. The ratio of width to length should be 
preferably 1:20-100, but may have extended variations. The size of the 
openings may be changed in further manufacturing steps. Adjacent openings 
may be divided just by the thickness of the comprising fiber or by more 
dense areas. 
In the invention, the fibrous thermal adhesive sheet by its composition 
acts itself as a thermal adhesive, usable in apparel or nonapparel 
lamination processes, by means of fusing presses or heated pressure 
rollers. This lightweight thermal adhesive is beneficial for laminating 
lightweight fabrics without the crackiness of thermal adhesive films. 
In the invention, the above-described fibrous thermally adhesive nonwoven 
sheet is combined with a thermally adhesive web with randomly arranged 
fusible polymeric filaments or parallel fusible polymeric filaments 
interconnected by randomly arranged fusible polymeric filaments. The 
composite may be interconnected by means of heat or pressure or a 
combination of both. 
The thermal adhesive nonwoven sheet may comprise about 5-60% of the weight 
of the composite web thermoplastic fibers and filaments 40-98% of teh 
composite web. The weight of the composite is about 10 g/sq.m to below 180 
g/sq.m. In this composite, the fibrous thermally adhesive nonwoven sheet 
provides the necessary tensile strength. The randomly arranged openings 
allow the penetration of the thermally adhesive components to either side 
of the nonwoven sheet if temperature and pressure are applied onto the 
composite. This build-up enables the composite to perform similar to an 
adhesive web. 
In the manufacturing process, the thermally adhesive nonwoven sheet may act 
as a carrier onto which the thermal adhesive polymeric web is applied in a 
known manner of adhesive web production. 
The composite of the present invention has unexpectedly improved 
properties, i.e. improved tensile strength; good adhesion to various 
outerfabrics (i.e. cotton/PES, PES, nylon, cotton, etc.) from one side to 
the other; and ease of manufacturing without a carrying sheet. These 
improved properties not only improve the manufacturing of the invention 
but also allow such materials to now be used for those applications where 
the higher strengths are mandatory or preferred. 
EXAMPLE 1A 
A nonwoven fleece of 12 g/m.sup.2 weight was formed by a carding operation 
using a fibermix of 30% by weight of thermal adhesive polymeric fibers 
(copolyesters) 3.5d.times.1.5" melting at 130.degree. C. and 70% of 
regular polyethylene-terephthalate (PET) staple fibers 3d.times.2". The 
interconnection for the fibers occured by using dispersed polyester based 
polymeric binder (Eastman WD size). A drying operation on multiple sets of 
steamheated cans (Steampressure 20-30 psi) followed. The dry weight of 
binder added win 4 g/m.sup.2 for a total weight of 16 g/m.sup.2. The 
nonwovens sheet had a fiber:binder ratio of 75:25 and a density of 0.039 
g/cm.sup.3. 
EXAMPLE 1B 
Onto the fleece of Example 1A, 50 g/m.sup.2 of a thermally adhesive web was 
applied comprising a copolyester with a melting range of 
130.degree.-135.degree. C. The forming of the composite occured by using a 
combination of heat and pressure by means of calender rollers. The 
temperature was 85.degree. C. and the pressure was 20 psi. 
EXAMPLE 2A 
A nonwoven fleece of 17 g/sq.m weight was formed by a carding operation 
using a fibermix of 30% by weight of thermal adhesive polymeric fibers (a 
copolyester sold by Eastman Kodak under the designation "Kodel 438") 
melting at 130.degree. C. and 70% of regular polyethylene-terephthalate 
(PET) staple fibers, 3 denier by 2 in. The interconnection of the fibers 
occurred by using a dispersed polyester based polymeric binder (Eastman WD 
size). A drying operation on multiple sets of steam heated cans followed. 
The steam pressure was 20-30 psi at 110.degree. C. The total weight of the 
bonded fleece was 22 g/m.sup.2. 
EXAMPLE 2B 
Onto the fleece of Example 2A, 62 g/m.sup.2 of a thermally adhesive web was 
applied comprising a copolyester with a melting range of 
130.degree.-135.degree. C. The forming of the composite occurred by using 
a combination of heat and pressure by means of calender rollers. The 
temperature was 85.degree. C. and the pressure was 20 psi. 
EXAMPLE 3A 
A nonwoven fleece of 14 g/sq.m weight was formed by a carding operation 
using a fibermix of 50% by weight of thermal adhesive polymeric fibers, as 
in Example 1, and 50% of regular polyethylene-terephthalate (PET) fibers. 
The interconnection of the fibers occurred by using a polymeric binder, as 
in Example 1, with a consecutive drying operation. The total wight of the 
bonded fleece was 18 g/sq.m. 
EXAMPLE 3B 
Onto this fleece, 80 g/m.sup.2 of a thermally adhesive web of a copolyester 
with a melting range of 110.degree.-115.degree. C. was applied. The 
forming of the composite occurred by using a combination of heat and 
pressure by means of calendar rollers. The temperature was 70.degree. C. 
and the pressure was 20 psi. 
EXAMPLE 4A 
A nonwoven fleece of 10 g/sq.m weight was formed by a carding operation 
using a fibermix of 60% by weight of the thermal adhesive polymeric 
fibers, as in Example 1, and 40% of regular polyethylene-terephthalate 
(PET) fibers. The interconnection of the fibers occurred by using a 
combination of heat and pressure by means of heated calender rollers. The 
temperature was 105.degree. C. and pressure was 20 kp per cm (kiloponds 
per cm., 1 kp=9.807 Newtons). 
EXAMPLE 4B 
Onto this fleece 50 g/sq.m of a thermally adhesive web was applied 
comprised of a terpolyamide of Nylon 6, Nylon 66 and Nylon 12 with a 
melting range of 110.degree.-120.degree. C. The forming of the composite 
occurred by using a combination of heat and pressure by means of calender 
rollers. The temperature was 70.degree. C. and the pressure was 20 psi. 
The composites of the invention show improved tensile strengths as recorded 
in Table 1. 
TABLE 1 
______________________________________ 
(Tensile/elongation properties of composite adhesive webs) 
Tensile Weight Elonga- 
Area Strength Related tion 
Type of therm. 
Weight (N/in.)** Tensile at 
adhesive web 
(g/sq.m) at break (Nm/g)**** 
break (%) 
______________________________________ 
Random 30 5.9 7.74 59 
PA*-Web 
Random 20 2.6 5.12 110 
PA*-Web 
Random 45 3.3 2.89 54 
PES***-Web 
Composite Web 
Ex. #1B 66 20.4 12.17 41 
Composite Web 
Ex. #2B 84 24.7 11.58 30 
Composite Web 
Ex. #3B 96 17.9 12.34 27 
Composite Web 
Ex. #4B 60 17.9 11.75 42 
______________________________________ 
*Nylon terpolymer of the Pellon SL8 type 
**Newtons per inch 
***Polyester Copolymer of the Pellon SP 20 type 
****Newtonmeter/gram 
It will be understood that the specification and examples are illustrative 
but not limitative of the present invention and that other embodiments 
within the spirit and scope of the invention will suggest themselves to 
those skilled in the art.