U.S. patent application number 11/940976 was filed with the patent office on 2008-05-29 for buffer layer for strings.
This patent application is currently assigned to NANO-PROPRIETARY, INC.. Invention is credited to Yunjun Li, Dongsheng Mao, Zvi Yaniv.
Application Number | 20080124546 11/940976 |
Document ID | / |
Family ID | 39186839 |
Filed Date | 2008-05-29 |
United States Patent
Application |
20080124546 |
Kind Code |
A1 |
Yaniv; Zvi ; et al. |
May 29, 2008 |
Buffer Layer for Strings
Abstract
A thin buffer layer is used to coat on the multi-filament
wrapped string to fill the gaps. The polymers of the buffer-layer
coating have a high melt-flow (low viscosity) during coating
process to fill all the gaps between the filaments, and the
filaments are fixed by the coatings onto base core materials.
Inventors: |
Yaniv; Zvi; (Austin, TX)
; Li; Yunjun; (Austin, TX) ; Mao; Dongsheng;
(Austin, TX) |
Correspondence
Address: |
FISH & RICHARDSON P.C.
P.O BOX 1022
Minneapolis
MN
55440-1022
US
|
Assignee: |
NANO-PROPRIETARY, INC.
Austin
TX
|
Family ID: |
39186839 |
Appl. No.: |
11/940976 |
Filed: |
November 15, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60866199 |
Nov 16, 2006 |
|
|
|
Current U.S.
Class: |
428/377 ;
427/206 |
Current CPC
Class: |
D07B 1/165 20130101;
D07B 2205/3007 20130101; D07B 2201/2074 20130101; D07B 2205/10
20130101; D07B 2201/1036 20130101; D07B 2201/2087 20130101; D07B
2205/3007 20130101; D07B 1/02 20130101; D07B 2205/2046 20130101;
D07B 2205/2046 20130101; D07B 2801/20 20130101; D07B 2801/22
20130101; D07B 2801/16 20130101; D07B 2801/22 20130101; D07B
2205/10 20130101; D07B 1/162 20130101; Y10T 428/2936 20150115; A63B
51/02 20130101; G10D 3/10 20130101 |
Class at
Publication: |
428/377 ;
427/206 |
International
Class: |
D02G 3/00 20060101
D02G003/00 |
Claims
1. A coating for a string, comprising: a core filament wrapped with
a plurality of wrapping filaments of a smaller diameter than the
core filament; a buffer layer coating filling in gaps between the
wrapping filaments and between the wrapping filaments and the core
filament; and an outer coating covering over the buffer layer
coating, wrapping filaments and core filament.
2. The coating of claim 1, wherein the buffer layer coating
comprises a polymer.
3. The coating of claim 1, wherein the buffer layer coating
comprises nylon.
4. The coating of claim 3, wherein the buffer layer coating
comprises nylon 6.
5. The coating of claim 3, wherein the buffer layer coating
comprises nylon 11.
6. The coating of claim 3, wherein the outer coating comprises a
composite of nylon and clay nanoparticles.
7. The coating of claim 3, wherein the outer coating comprises a
composite of nylon and carbon nanotubes.
8. The coating of claim 6, wherein the outer coating further
comprises a modifier.
9. A method for coating a string comprising: wrapping a core
filament having a first diameter with one or more wrapping
filaments having a second diameter that is less than the first
diameter; extruding a melted nylon into gaps between the one or
more wrapping filaments and into gaps between the wrapping
filaments and the core filament; extruding a coating on a
circumference of the string so that it covers the one or more
wrapping filaments and the melted nylon in the gaps.
10. The method of claim 9, wherein the melted nylon comprises nylon
6.
11. The method of claim 9, wherein the melted nylon comprises nylon
11.
12. The method of claim 9, wherein the coating comprises a
composite of nylon and clay nanoparticles.
13. The method of claim 9, wherein the coating comprises a
composite of nylon and carbon nanotubes.
14. The method of claim 9, wherein the coating comprises a
composite of nylon and ceramic particles.
15. The method of claim 9, wherein the coating comprises a
composite of nylon and glass particles.
16. The method of claim 9, wherein the coating is between 1 and 100
micrometers thick.
17. The coating of claim 1, further comprising: another plurality
of wrapping filaments wrapped around the outer coating; another
buffer layer coating filling in gaps between the another plurality
of wrapping filaments; and another outer coating covering over the
another buffer layer coating.
18. The coating of claim 3, wherein the coating comprises a
composite of nylon and glass particles.
19. The coating of claim 3, wherein the coating comprises a
composite of nylon and ceramic particles.
Description
[0001] This application claims priority to U.S. Provisional
Application Ser. No. 60/866,199, which is hereby incorporated by
reference hereby.
BACKGROUND
[0002] The strings for sports equipment (e.g., tennis raquets) or
musical instruments are usually coated with a thin layer at their
outmost surface to improve their durability, spin, feeling, etc.
Polyamide (nylon), polyester, and other polymers have been used to
coat on strings. Nanocomposites, such as clay and carbon nanotube
reinforced nylon 6 nanocomposites, having better physical
properties than neat nylon 6, are of a potential to be highly
durable string coating materials with other functionalities. The
reinforcing polymeric composites using nano-sized clay particles
with high aspect ratio have been investigated since the 1980's (see
U.S. Pat. No. 4,739,007). Strings are usually polymer materials
with a multi-layer structure--core filament, wrapping filaments on
the core filament, and coating. For the strings with multi-layer
structures, coating materials are required to match the base
materials and have good melt-flow properties (acceptable viscosity)
at certain temperature to allow them to be penetrated into the gaps
between the wrapping filaments. Viscosity of a nanocomposite is
usually higher than neat nylon 6 at the same temperature. Thus, the
nanocomposite may not easily penetrate into the gaps between the
wrapping filaments. FIG. 1 shows an SEM image of a cross-section
view of a nylon 6/clay nanocomposite coated on a wrapping filament.
It can be seen that the nanocomposite material did not successfully
fill out the gaps. Many defects were left in the string which will
result in unacceptable durability of the strings. The gaps will
result in chipping-off or unacceptable durability of coatings
during high impact hitting of balls. More over, due to creation of
the gaps, coatings also fail to a fix the filaments on the core
materials of the string. FIG. 2 shows the chipped materials from
filaments and coatings after high impact tests on the strings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] FIG. 1 shows an SEM image of a cross-section view of a nylon
6/clay nanocomposite coated on a wrapping filament;
[0004] FIG. 2 shows an SEM image of chipped materials from
filaments and coatings after high impact tests on a string;
[0005] FIG. 3A illustrates a cross-section of a core filament with
wrapping filaments surrounding it;
[0006] FIG. 3B illustrates a buffer layer applied onto the wrapping
filament;
[0007] FIG. 3C illustrates a coating applied onto the buffer layer;
and
[0008] FIG. 4 illustrates another embodiment of the present
invention.
DETAILED DESCRIPTION
[0009] Although polymer nanocomposites have higher
physical/mechanical properties than neat polymer materials, they
normally have higher viscosity or melt-flow during an extrusion or
coating process. To solve this problem, a thin buffer layer is used
to coat on the multi-filament wrapped string to fill the gaps. The
polymers of the buffer-layer coating have a high melt-flow (low
viscosity) during coating process to fill all the gaps between the
filaments, and the filaments are fixed by the coatings onto base
core materials.
Example 1
A Coating System with a Nylon 6 Buffer Layer
[0010] FIG. 3A illustrates a cross-section of a string for coating
comprised of one monofilament core 301 wrapped with
smaller-diameter multi-filaments 302. Neat nylon 6 pellets as may
be obtained from UBE Industries Inc. (product name: UBE SF 1018 A)
are melted. The buffer layer coating 303 is applied by an extrusion
process at temperatures ranging from 220.degree. C. to 270.degree.
C. The thickness of the buffer layer 303 may be from 10 to 100
micrometers. The gaps between the multi-filaments 302 are fully
filled by the neat nylon 6 coating.
[0011] A wear-resistant coating 304 is then coated (FIG. 3C) by an
extrusion process at temperatures ranging from 240.degree. C. to
280.degree. C. A nylon 6/clay or nylon 6/carbon nanotube
nanocomposite may be employed as the wear-resistant coating
material 304. The nylon 6 nanocomposite produced by in-situ
polymerization may contain 4% nano-clay filler. Other nylon 6
nanocomposites produced by melt-compounded process may also be used
for the wear-resistant coatings 304. Except for the clay, carbon
nanotubes, ceramic particles such as SiO.sub.2 and Al.sub.2O.sub.3,
or glass particles may be used to make nylon 6 nanocomposites. The
Nylon 6 nanocomposites may also be modified by rubber modifiers to
improve the ductility and toughness. The thickness of the
wear-resistant coating may be from 1 to 100 micrometers.
Example 2
A Coating System with a Nylon 11 Buffer Layer
[0012] Again referring to FIG. 3A, the string for coating is one
monofilament core 301 wrapped with smaller-diameter multi-filaments
302. Neat nylon 11 may be obtained from ARKEMA Inc. Nylon 11 has a
very good melt flow at temperatures over 220.degree. C. Good impact
strength and shear strength also make nylon 11 a good buffer layer
material. In FIG. 3B, the buffer layer coating 303 is applied by an
extrusion process at temperatures ranging from 190.degree. C. to
270.degree. C.
[0013] The thickness of the buffer layer 303 may be from 10 to 100
micrometers. The gaps between the multi-filaments 302 are fully
filled by the neat nylon 11 coating.
[0014] Referring to FIG. 3C, a wear-resistant coating 304 is then
coated by an extrusion process at temperatures ranging from
240.degree. C. to 280.degree. C. Nylon 6/clay or a nylon 6/carbon
nanotube nanocomposite may be employed as the wear-resistant
coating material 304. The nylon 6 nanocomposite produced by in-situ
polymerization may contain 4% nano-clay filler. Other nylon 6
nanocomposites produced by melt-compounded process may also be used
for the wear-resistant coating 304. The nylon 6 nanocomposites may
also be modified by rubber modifiers to improve the ductility and
toughness. The thickness of the wear-resistant coating 304 may be
from 1 to 100 micrometers.
[0015] Except for the extrusion process to deposit a coating on the
string, other methods such as spraying, dipping, spin coating,
brushing, painting, and immersing processes can be used to deposit
a coating on the surface of strings. Nylon 6 nanocomposites may be
melted at higher than 190.degree. C. and extruded to deposit a
coating on the strings. Nylon 6 nanocomposites may be dissolved in
a solvent such as formic acid and sprayed, dipped, spin coated,
brushed, painted, or immersed to deposit a coating on the string at
room temperature or elevated temperatures. The solvent may be then
removed by a follow-up process such as an evaporation method.
[0016] FIG. 4 illustrates another embodiment of the present
invention. Essentially, the coated string structure of FIG. 3C is
then coated again with smaller-diameter multi-filaments 401. A
buffer layer coating 402, similar to layer 303, is applied by an
extrusion process at temperatures ranging from 190.degree. C. to
270.degree. C. The thickness of the buffer layer 402 may be from 10
to 100 micrometers. The gaps between the multi-filaments 401 are
fully filled by the neat nylon 11 coating. A wear-resistant coating
403 is then coated by an extrusion process at temperatures ranging
from 240.degree. C. to 280.degree. C. Nylon 6/clay or a nylon
6/carbon nanotube nanocomposite may be employed as the
wear-resistant coating material 403. The nylon 6 nanocomposite
produced by in-situ polymerization may contain 4% nano-clay filler.
Other nylon 6 nanocomposites produced by melt-compounded process
may also be used for the wear-resistant coating 403. The nylon 6
nanocomposites may also be modified by rubber modifiers to improve
the ductility and toughness. The thickness of the wear-resistant
coating 403 may be from 1 to 100 micrometers.
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