U.S. patent application number 11/076298 was filed with the patent office on 2005-07-21 for bonding of a fluoropolymer layer to a substrate.
This patent application is currently assigned to 3M Innovative Properties Company. Invention is credited to Arren, Dirk H., Coggio, William D., Fukushi, Tatsuo, Govaerts, Ludo, Hintzer, Klaus, Kaspar, Harald.
Application Number | 20050159558 11/076298 |
Document ID | / |
Family ID | 23315939 |
Filed Date | 2005-07-21 |
United States Patent
Application |
20050159558 |
Kind Code |
A1 |
Govaerts, Ludo ; et
al. |
July 21, 2005 |
Bonding of a fluoropolymer layer to a substrate
Abstract
The present invention comprises a substrate having a
fluoropolymer on at least one of its surfaces wherein one of the
substrates or the fluoropolymer comprises a hydride function MH
wherein M is Si, Ge, Sn or Pb. The invention further comprises
articles comprising the substrate and fluoropolymer; a method of
bonding the fluoropolymer to the substrate; a fluoropolymer
composition that contains the fluoropolymer, a polyhydroxy cure
composition, and an organic composition comprising the hydride
function MH; a premix that contains the fluoropolymer and the
hydride function MH; and a fluoropolymer composition that comprises
(a) a thermoplastic fluoropolymer comprising Cl, Brand/or I atoms
and (b) an organic compound that comprises the hydride function
MH.
Inventors: |
Govaerts, Ludo; (Ranst,
BE) ; Arren, Dirk H.; (Schoten, BE) ; Fukushi,
Tatsuo; (Woodbury, MN) ; Coggio, William D.;
(Hudson, WI) ; Hintzer, Klaus; (Kastl, DE)
; Kaspar, Harald; (Burgkirchen, DE) |
Correspondence
Address: |
3M INNOVATIVE PROPERTIES COMPANY
PO BOX 33427
ST. PAUL
MN
55133-3427
US
|
Assignee: |
3M Innovative Properties
Company
|
Family ID: |
23315939 |
Appl. No.: |
11/076298 |
Filed: |
March 9, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11076298 |
Mar 9, 2005 |
|
|
|
10282677 |
Oct 29, 2002 |
|
|
|
60336405 |
Oct 31, 2001 |
|
|
|
Current U.S.
Class: |
525/326.3 ;
525/326.2; 525/384; 525/387 |
Current CPC
Class: |
Y10T 428/1393 20150115;
B32B 7/10 20130101; C08L 27/12 20130101; B32B 27/28 20130101; C08K
5/54 20130101; C08K 5/54 20130101; B32B 25/08 20130101; B32B 1/08
20130101 |
Class at
Publication: |
525/326.3 ;
525/326.2; 525/387; 525/384 |
International
Class: |
C08F 014/18 |
Claims
What is claimed is:
1. Fluoropolymer composition comprising: (a) a thermoplastic melt
processible semi-crystalline fluoropolymer comprising chlorine,
bromine and/or iodine atoms; and (b) an organic compound comprising
a hydride function MH, wherein M is selected from Si, Ge, Sn and
Pb.
2. A fluoropolymer according to claim 1 wherein said fluoropolymer
is a copolymer of tetrafluoroethylene and/or vinylidene fluoride
and one or more comonomers selected from the group consisting of a
chlorine containing monomer, ethylene, propylene,
hexafluoropropylene, fluorinated vinyl ethers and fluorinated allyl
ethers.
3. A fluoropolymer according to claim 1 wherein said fluoropolymer
is a copolymer of tetrafluoroethylene and/or vinylidene fluoride
and one or more comonomers selected from the group consisting of
chlorotrifluoroethylene, vinyl chloride, vinylidene chloride,
ethylene, propylene, perfluorinated vinyl ethers and
hexafluoropropylene.
4. Fluoropolymer composition comprising: (a) a fluoropolymer; (b) a
cure composition comprising a polyhydroxy compound; and (c) a
silazane.
5. A fluoropolymer according to claim 4 wherein said fluoropolymer
is a copolymer of tetrafluoroethylene and/or vinylidene fluoride
and one or more comonomers selected from the group consisting of a
chlorine containing monomer, ethylene, propylene,
hexafluoropropylene, fluorinated vinyl ethers and fluorinated allyl
ethers.
6. A fluoropolymer according to claim 4 wherein said fluoropolymer
is a copolymer of tetrafluoroethylene and/or vinylidene fluoride
and one or more comonomers selected from the group consisting of
chlorotrifluoroethylene, vinyl chloride, vinylidene chloride,
ethylene, propylene, perfluorinated vinyl ethers and
hexafluoropropylene.
7. A fluoropolymer according to claim 4 wherein said silazane is a
disilazane corresponding to the formula:
H.sub.uSi(R.sup.f).sub.3-u--NR.s- up.g--SiH.sub.u(R.sup.h).sub.3-u
wherein u is 1 or 2, R.sup.f and R.sup.h each independently
represents an alkyl group or an aryl group and R.sup.g represents
hydrogen, an alkyl group or an aryl group.
8. A fluoropolymer according to claim 7 wherein said disilazane is
HSi(CH.sub.3).sub.2--NH--Si(CH.sub.3).sub.2H.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. Ser. No.
10/282,677, filed Oct. 29, 2002, now allowed, which claims priority
to Provisional Application No. 60/336,405, filed Oct. 31, 2001, the
disclosures of which are herein incorporated by reference.
FIELD
[0002] The present invention relates to an improvement in bonding
of a fluoropolymer, i.e. a polymer having a fluorinated backbone,
to a substrate such as for example a non-fluorinated elastomer,
silicone elastomer or even another fluoropolymer such as for
example a layer of a thermoplastic fluoropolymer. In particular,
the present invention relates to the use of an organic compound
having a hydride function MH, wherein M is selected from Si, Ge, Sn
and Pb to improve the bonding properties of a fluoropolymer.
BACKGROUND
[0003] The beneficial properties of fluoropolymers are well known
in the art and include for example, high temperature resistance,
high chemical resistance including for example high resistance to
solvents, fuels and corrosive chemicals, and non-flammability.
Because of these beneficial properties, fluoropolymers find wide
application particularly where materials are exposed to high
temperature and/or chemicals.
[0004] For example, fluoropolymers are used in fuel management
systems which include for example fuel tanks, fuel filler lines and
fuel supply lines in cars or other motor vehicles because of their
excellent resistance to fuels and because of the good barrier
properties that can be achieved with fluoropolymers. Additionally,
fluoropolymers, in particular fluoroelastomers, may be used in a
hose connecting the compressor of a turbo engine with an
intercooler. Because of the high temperature of the compressed air,
non-fluorine elastomers such as ethylene acrylic based elastomers
or silicone elastomers cannot be used for such a hose.
[0005] Fluoropolymers are generally more expensive than
non-fluorine polymers and accordingly, materials have been
developed in which the fluoropolymer is used in combination with
other materials to reduce the overall cost of an article. For
example, in the aforementioned hose used in turbo engines, it has
been proposed to use a relatively thin layer of fluoroelastomer as
an inner layer of a multilayer hose where the outerlayer of the
hose is then a non-fluorine elastomer such as for example a
silicone elastomer. It is required in such a multilayer hose that
the fluoropolymer layer be firmly and reliably bonded to the other
layers of the hose. Unfortunately, bonding of fluoropolymers to
other substrates is often difficult and in particular bonding to
silicone elastomers has been found difficult. This is further
complicated by the fact that various silicone compositions exist
such that in one instance a particular fluoropolymer composition
may show good bonding, yet in another instance satisfactory bonding
may not be obtained. To solve this problem, tie layers have been
proposed between the fluoropolymer and other materials such as a
silicone elastomer, but this increases cost and makes the
manufacturing more complicated.
[0006] A further application in which a multi-layer article
including a fluoropolymer layer is used is in a fuser member of a
plain paper copier. Such a fuser member typically has a thermally
conductive silicone elastomer which is bonded to a fluoroelastomer
surface layer which may also include conductive particles. Such a
fuser member is disclosed in for example U.S. Pat. No. 5,217,837.
This U.S. patent describes a multilayer fuser member in which the
silicone elastomer is bonded to the fluoroelastomer with the
intermediate of an adhesive layer. The manufacturing of such a
fuser member is unfortunately cumbersome. A similar system is
described in U.S. Pat. No. 6,020,038.
[0007] Further, in certain applications, it may further be
desirable to bond fluoropolymers of different nature and
composition to each other. For example, in a fuel supply line, it
may be desirable to bond a fluoroelastomer layer to
fluorothermoplastic polymer layer. Although both polymers are
fluoropolymers, desired bond strength may still not be
achieved.
[0008] Accordingly, it would be desirable to find a way of
improving bonding of a fluoropolymer to other substrates such as
for example non-fluorine elastomers, silicone rubbers and other
fluoropolymers. Preferably, this solution is cost effective,
convenient and reliable and can be applied to a wide variety of
substrates.
SUMMARY
[0009] In one embodiment, the present invention provides a material
comprising a substrate having on at least one surface thereof a
fluoropolymer layer comprising a fluoropolymer. The fluoropolymer
layer and/or the substrate comprises an organic compound comprising
a hydride function MH, wherein M is selected from Si, Ge, Sn and
Pb. This material can be formed into an article in which the
fluoropolymer is firmly bonded to the substrate by reacting the
fluoropolymer layer to the substrate. Accordingly, the invention
further provides the article that is obtained from reacting the
fluoropolymer layer to the substrate.
[0010] In a further aspect, the present invention provides a method
of bonding a fluoropolymer to a substrate comprising reacting the
fluoropolymer layer to the substrate in the presence of an organic
compound having a hydride group comprising a hydride function MH,
wherein M is selected from Si, Ge, Sn and Pb.
[0011] It has been found in connection with the present invention
that a fluoropolymer layer can be effectively bonded to a substrate
if an organic compound having a hydride function MH is present. In
particular, good bonding of a fluoroelastomer layer to other
elastomers, including non-fluorine type elastomers such as silicone
rubbers can be obtained. Surprisingly, these good bonding
properties can be obtained with a wide variety of silicone rubber
compositions.
[0012] In a further aspect, the present invention relates to a
particular fluoropolymer composition that can be used for bonding a
fluoroelastomer layer to a substrate. This aspect of the invention
provides a fluoropolymer composition that comprises:
[0013] (a) a fluoropolymer;
[0014] (b) a cure composition comprising a polyhydroxy compound;
and
[0015] (c) an organic compound comprising a hydride function MH,
wherein M is selected from Si, Ge, Sn and Pb.
[0016] In yet a still further aspect, the present invention
provides a premix for providing a curable fluoropolymer
composition, said premix comprising a fluoropolymer and an organic
compound comprising a hydride function MH, wherein M is selected
from Si, Ge, Sn and Pb, and said curable fluoropolymer composition
being obtainable from said premix by adding thereto one or more
components of a cure composition.
[0017] In a further aspect, a fluoropolymer composition is provided
that comprises:
[0018] (a) a thermoplastic fluoropolymer comprising chlorine,
bromine and/or iodine atoms; and
[0019] (b) an organic compound comprising a hydride function MH,
wherein M is selected from Si, Ge, Sn and Pb.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] The following figures are included by way of further
illustration of some embodiments of the present invention. It will
be understood that these drawings merely serve to illustrate the
invention without limiting the invention in any way thereto.
[0021] FIGS. 1 and 2 are cross-sectional schematic representations
of a multi-layer hose or tube that can be obtained with the
invention.
DETAILED DESCRIPTION
[0022] The organic compound having one or more hydride functions MH
may either be a simple organic compound or a polymeric compound. By
"polymeric compound" is meant that the compound comprises repeating
units that are actually or conceptually derived from lower
molecular weight compounds, i.e. monomers. The polymerization
degree may vary widely and includes a low polymerization degree
such as for example a polymerization degree of 2 to 50 repeating
units as well as a large polymerization degree of more than 50.
Thus, the term "polymeric compound" should be understood to include
oligomeric compounds that typically have a low polymerization
degree. If the organic compound is polymeric, the hydride function
may be contained in the terminating group of the polymeric chain
and/or in a repeating unit of the polymeric compound.
[0023] The organic compound having one or more MH functions is
typically a non-fluorinated compound although the possibility of
using an organic compound that has fluorine substituents is not
excluded.
[0024] In one embodiment of the present invention, the organic
compound is a siloxane or a silazane that comprises one or more MH
functions. Typically, when the organic compound is a siloxane or a
silazane, the MH functions will be --SiH functions. Preferably, the
SiH function will be an --OSiH or a --NSiH whereby the hydrogen is
attached to a silicon atom that is further bonded to an oxygen or
nitrogen atom. The siloxane or silazane may be a simple low
molecular weight organic compound or may be a polymeric compound
including for example a polysiloxane which may be linear, branched
or cyclic.
[0025] Examples of low molecular weight siloxanes include for
example alkoxy silanes corresponding to the formula:
(R.sup.a).sub.a(R.sup.bO).sub.tSiH.sub.w (I)
[0026] wherein each R.sup.a independently represents an alkyl group
such as for example methyl or ethyl or another lower alkyl
(C.sub.1-C.sub.7 alkyl group) or an alkyl group substituted with a
substituent such as for example an aryl group, an ester, an alkoxy
etc., or aryl group optionally substituted such as for example with
an alkyl group, an ester, an alkoxy etc.; each R.sup.b
independently represents an alkyl group, preferably a lower alkyl
group and which may optionally be substituted; t and w represent an
integer of at least 1 and the sum of s+t+w being 4. Examples of
siloxanes according to the above formula include
HSi(OCH.sub.2CH.sub.3).sub.3 and
(CH.sub.3).sub.2(CH.sub.3CH.sub.2O)SiH.
[0027] In accordance with another embodiment of the present
invention, the organic compound is a polysiloxane (oligomer or
polymer), comprising a polysiloxy backbone. Such polymer or
oligomer may be terminated by a group containing one or more SiH
functions and/or may contain SiH groups distributed along the
backbone. The SiH groups may form part of the backbone or they can
be present in a side group attached to the backbone.
[0028] For example, the polysiloxanes for use with this invention
include those that correspond to the formula: 1
[0029] wherein R.sup.1, R.sup.2, R.sup.3, R.sup.6, R.sup.7, R.sup.8
and R.sup.9 each independently represents hydrogen, an alkoxy
group, an alkyl optionally substituted such as for example with an
aryl group, an ester, an alkoxy etc., or aryl group optionally
substituted such as for example with an alkyl group, an ester, an
alkoxy etc.; R.sup.4 and R.sup.5 each independently represents an
alkoxy group, an alkyl or aryl group each of which may optionally
be substituted, x represents a value of 0 to 150, y represents a
value of 0 to 150 and with the proviso that when x=0, at least one
of R.sup.1, R.sup.2, R.sup.6, R.sup.7, R.sup.8 and R.sup.9
represents a hydrogen atom.
[0030] Specific examples of siloxanes include 1,1,3,3
tetraisopropyl disiloxane,
diphenyl-1,1,3,3-tetrakis(dimethylsiloxy)disiloxane available from
United Chem, silylhydride terminated poly(dimethylsiloxane),
poly(methyl hydro siloxane) and copolymers of dimethylsiloxane and
methylhydrosiloxane.
[0031] Further siloxanes that can be used may be cyclic such as
those corresponding to the formula: 2
[0032] wherein R.sup.c represents hydrogen, an alkyl group or an
aryl group, R.sup.d and R.sup.e each independently represents an
alkyl or aryl group, i is at least 1 and the sum of i+j is at least
3. Specific examples of cyclic siloxanes according to the above
formula are 1,3,5-trimethyl cyclosiloxane and
1-phenyl-3,3,5,5-tetramethyl cyclosiloxane.
[0033] Polysiloxanes and siloxanes having SiH groups are known in
the art and can be produced according to well-known procedures such
as disclosed in for example: Encyclopedia of Polymer Science and
Engineering, Second Edition, V15, Silicones, pgs. 204-308, John
Wiley & Sons, 1989. Siloxanes having SiH groups are also
generally commercially available. Preferably, the siloxane or
polysiloxane will have a molecular weight between 150 g/mol and
10,00 g/mol.
[0034] Suitable silazanes for use with the invention include for
example disilazanes corresponding to the formula:
H.sub.uSi(R.sup.f).sub.3-u--NR.sup.g--SiH.sub.u(R.sup.h).sub.3-u
(IV)
[0035] wherein u is 1 or 2, R.sup.f and R.sup.h each independently
represents an alkyl group or an aryl group and R.sup.g represents
hydrogen, an alkyl group or an aryl group. A specific example of a
silazane is HSi(CH.sub.3).sub.2--NH--(CH.sub.3).sub.2H.
[0036] In a further embodiment of the present invention, the
organic compound corresponds to the formula: 3
[0037] wherein R represents a hydrocarbon group optionally
comprising one or more substituents and wherein the R groups may be
the same or different and whereby two R groups may be linked to
each other so as to form a ring, M is selected from Si, Ge, Sn and
Pb, q is a value of 1 to 3, x is a value of 1 to 3, y and z
represent a value of 0 to 3 and the sum of y+z=4-x. Examples of
substituents that may be present on the hydrocarbon group R include
alkoxy, aryloxy, halogens such as chlorine and bromine, nitrile
groups, hydroxy groups and amino groups. The backbone of the
hydrocarbon group may further be interrupted by one or more
heteroatoms such as for example oxygen and nitrogen atoms. Typical
examples of hydrocarbon groups include saturated or unsaturated
linear, branched or cyclic aliphatic groups and aromatic groups.
Specific examples are C.sub.1-C.sub.5 alkyl groups, aryl groups
having 6 to 12 carbon atoms, arylalkyl and alkylaryl groups having
7 to 14 carbon atoms.
[0038] Compounds according to formula (V) include in particular
those according to formula (VI):
R.sub.ySi--H.sub.x (VI)
[0039] wherein R, y and x have the same meaning as above.
Preferably, R in the above formula (VI) is an aryl group such as
for example phenyl.
[0040] Compounds of formula (V) and (VI) are known and have been
described in for example J. Am. Chem. Soc., 116 (1994), page
4521-4522. Examples of compounds according to formula V include
tri(n-butyl)tin hydride, tri(ethyl)silyl hydride,
di(trimethylsilyl)silylmethyl hydride, tri(trimethylsilyl)silyl
hydride, tri(phenyl)silyl hydride. Compounds of formula (V) have
further been disclosed in EP 761 735.
[0041] The organic compound is typically included in a composition
for providing the fluoropolymer layer. However, this may not be
necessary and it is also contemplated that the organic compound is
included in the substrate to which the fluoropolymer is to be
bonded in particular in the surface layer of the substrate to which
the fluoropolymer is being bonded. The amount of organic compound
used in a composition for providing the fluoropolymer layer may
vary widely and the optimal amount can be readily determined by one
skilled in the art through routine experimentation. Typically, an
amount of 0.01% by weight to 5% by weight, preferably between 0.1%
by weight and 4% by weight based on the weight of fluoropolymer is
included in the composition for preparing the fluoropolymer
layer.
[0042] The fluoropolymer of the fluoropolymer layer may have a
partially or fully fluorinated backbone. Particularly preferred
fluoropolymers are those that have a backbone that is at least 30%
by weight fluorinated, preferably at least 50% by weight
fluorinated, more preferably at least 65% by weight
fluorinated.
[0043] Examples of fluoropolymers for use in this invention include
polymers of one or more fluorinated monomers optionally in
combination with one or more non-fluorinated monomers. Examples of
fluorinated monomers include fluorinated C.sub.2-C.sub.8 olefins
that may have hydrogen and/or chlorine atoms such as
tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE),
2-chloropentafluoropropene, dichlorodifluoroethylene, vinyl
fluoride, vinylidene fluoride (VDF) and fluorinated alkyl vinyl
monomers such as hexafluoropropylene (HFP); fluorinated vinyl
ethers, including perfluorinated vinyl ethers (PVE) and fluorinated
allyl ethers including perfluorinated allyl ethers. Suitable
non-fluorinated comonomers include vinyl chloride, vinylidene
chloride and C.sub.2-C.sub.8 olefins such as ethylene (E) and
propylene (P).
[0044] Examples of perfluorovinyl ethers that can be used in the
invention include those that correspond to the formula:
CF.sub.2.dbd.CF--O--R.sub.f
[0045] wherein R.sub.f represents a perfluorinated aliphatic group
that may contain one or more oxygen atoms.
[0046] Particularly preferred perfluorinated vinyl ethers
correspond to the formula:
CF.sub.2.dbd.CFO(R.sup.a.sub.fO).sub.n(R.sup.b.sub.fO).sub.mR.sup.c.sub.f
[0047] wherein R.sup.a.sub.f and R.sup.b.sub.f are different linear
or branched perfluoroalkylene groups of 1-6 carbon atoms, in
particular 2 to 6 carbon atoms, m and n are independently 0-10 and
R.sup.c.sub.f is a perfluoroalkyl group of 1-6 carbon atoms.
Specific examples of perfluorinated vinyl ethers include perfluoro
(methyl vinyl) ether (PMVE), perfluoro (ethyl vinyl) ether (PEVE),
perfluoro (n-propyl vinyl) ether (PPVE-1),
perfluoro-2-propoxypropylvinyl ether (PPVE-2),
perfluoro-3-methoxy-n-propylvinyl ether,
perfluoro-2-methoxy-ethylvinyl ether and
CF.sub.3--(CF.sub.2).sub.2--O--CF(CF.sub.3)--CF.sub.2--O--CF(CF-
.sub.3)--CF.sub.2--O--CF.dbd.CF.sub.2.
[0048] Suitable perfluoroalkyl vinyl monomers correspond to the
general formula:
CF.sub.2.dbd.CF--R.sup.d.sub.f or
CH.sub.2.dbd.CH--R.sup.d.sub.f
[0049] wherein R.sub.d.sup.f represents a perfluoroalkyl group of 1
to 10, preferably 1 to 5 carbon atoms. A typical example of a
perfluoroalkyl vinyl monomer is hexafluoropropylene.
[0050] The fluoropolymers for use in connection with the present
invention can be made in accordance with any of the known
polymerization methods for making fluoropolymers. Such methods
include without limitation, aqueous emulsion polymerization,
suspension polymerization and polymerization in an organic
solvent.
[0051] According to a particular embodiment, the fluoropolymer is a
substantially amorphous polymer that shows hardly any melting point
if at all. Such fluoropolymers are particularly suitable for
providing fluoroelastomers, which are typically obtained upon
curing of an amorphous fluoropolymer. Amorphous fluoropolymers
include for example copolymers of vinylidene fluoride and at least
one terminally ethylenically-unsaturated fluoromonomer containing
at least one fluorine atom substituent on each double-bonded carbon
atom, each carbon atom of said fluoromonomer being substituted only
with fluorine and optionally with chlorine, hydrogen, a lower
fluoroalkyl radical, or a lower fluoroalkoxy radical. Specific
examples of copolymers include for example copolymers having a
combination of monomers as follows: VDF-HFP, TFE-P, VDF-TFE-HFP,
VDF-TFE-PVE, TFE-PVE, E-TFE-PVE and any of the aforementioned
copolymers further including units derived from a chlorine
containing monomer such as CTFE. Still further examples of suitable
amorphous copolymers include copolymers having a combination of
monomers as in CTFE-P.
[0052] Preferred amorphous fluoropolymers generally comprise from
20 to 85%, preferably 50 to 80% by moles of repeating units derived
from VDF, TFE and/or CTFE, copolymerized with one or more other
fluorinated ethylenically unsaturated monomer and/or one or more
non fluorinated C.sub.2-C.sub.8 olefins, such as ethylene and
propylene. The units derived from the fluorinated ethylenically
unsaturated comonomer when present is generally between 5 and 45
mole %, preferably between 10 and 35 mole %. The amount of
non-fluorinated comonomer when present is generally between 0 and
50 mole %, preferably between 1 and 30 mole %.
[0053] In an embodiment where a fluoroelastomer is desired, the
fluoropolymer will typically be cured. The fluoropolymer layer may
be cured by any of the methods known to those skilled in the art
and will typically include a cure composition such that the
fluoropolymer layer can be cured. The cure composition typically
includes one or more components that cause the fluoropolymer chains
to link with each other thereby forming a three dimensional
network. Such components may include catalysts, curing agents
and/or coagents.
[0054] In one embodiment of curing the fluoropolymer layer a so
called peroxide cure system may be used. In a typical peroxide cure
system, the fluoropolymer is provided with one or more cure sites
that comprise a halogen capable of participating in a peroxide cure
reaction and the composition for providing the fluoropolymer
contains an organic peroxide. The halogen capable of participating
in a peroxide cure reaction is typically bromine or iodine and may
be distributed along the polymer chain and/or may be contained in
the end groups of the fluoropolymer. Typically, the amount of
bromine or iodine contained in the fluoropolymer is between 0.001
and 5%, preferably between 0.01 and 2.5%, by weight with respect to
the total weight of the fluoropolymer. It has further been found
that chlorine is also capable of participating in a peroxide cure
reaction of the fluoropolymer if the organic compound having MH
functions is present. Accordingly, fluoropolymers that also contain
chlorine atoms and/or bromine or iodine can be used for curing in a
peroxide cure reaction. The amount of chlorine in the fluoropolymer
may vary from 0.001% by weight to 10% by weight but is typically
between 0.01% by weight and 5% by weight based on the weight of
fluoropolymer. A particularly suitable polymer for use with a
peroxide cure system is a polymer that includes units that are
derived from CTFE or another chlorine containing monomer. Specific
examples include copolymers that have a combination of
CTFE-VDF-TFE-HFP as monomers. Of course a chlorine containing
fluoropolymer for use in a peroxide cure system may additionally be
modified with bromine and/or iodine. The fluoropolymer for use in
the peroxide cure reaction typically will have a molecular weight
of 10.sup.4 to 5.times.10.sup.5 g/mol and the molecular weight
distribution can be monomodal as well as bimodal or multimodal.
[0055] In order to introduce halogens, which are capable of
participation in the peroxide cure reaction, along the chain, the
copolymerization of the basic monomers of the fluoropolymer is
carried out with a suitable fluorinated cure-site monomer (see for
instance U.S. Pat. Nos. 4,745,165, 4,831,085, and 4,214,060). Such
comonomer can be selected for instance from:
[0056] (a) bromo- or iodo-(per)fluoroalkyl-perfluorovinylethers
having the formula:
Z--R.sub.f--O--CF.dbd.CF.sub.2
[0057] wherein Z is Br or I, Rf is a (per)fluoroalkylene
C.sub.1-C.sub.12, optionally containing chlorine and/or ether
oxygen atoms; for example: BrCF.sub.2--O--CF.dbd.CF.sub.2,
BrCF.sub.2CF.sub.2--O--CF.dbd.CF.sub.2,
BrCF.sub.2CF.sub.2CF.sub.2--O--CF.dbd.CF.sub.2,
CF.sub.3CFBrCF.sub.2--O--- CF.dbd.CF.sub.2, and the like;
[0058] (b) bromo- or iodo (per)fluoroolefins such as those having
the formula:
Z'--R'.sub.f--CF.dbd.CF.sub.2
[0059] wherein Z' is Br or I, R'.sub.f is a (per)fluoroalkylene
C.sub.1-C.sub.12, optionally containing chlorine atoms; for
instance: bromotrifluoroethylene, 4-bromo-perfluorobutene-1, and
the like; or bromofluoroolefins such as
1-bromo-2,2-difluoroethylene and
4-bromo-3,3,4,4-tetrafluorobutene-1;
[0060] (c) non-fluorinated bromo-olefins such as vinyl bromide and
4-brorno-1-butene;
[0061] (d) chlorine containing monomers including chlorine
containing fluorinated monomers such as for example chlorine
containing fluorinated C.sub.2-C.sub.8 olefins such as CTFE and
non-fluorinated chlorine containing monomers such as chlorinated
C.sub.2-C.sub.8 olefins such as vinyl chloride and vinylidene
chloride.
[0062] In replacement of or in addition to the cure site comonomer,
the fluoropolymer can contain a cure site component in terminal
position, deriving from a suitable chain transfer agent introduced
in the reaction medium during the polymer preparation, as described
in U.S. Pat. No. 4,501,869 or derived from a suitable initiator.
Examples of useful initiators include X(CF.sub.2).sub.nSO.sub.2Na
with n=1 to 10 (where X is Br or I) or an initiator composition
comprising ammonium persulfate and potassium bromide.
[0063] Examples of chain transfer agents include those having the
formula R.sub.fBr.sub.x, wherein R.sub.f is a x-valent
(per)fluoroalkyl radical C.sub.1-C.sub.12, optionally containing
chlorine atoms, while x is 1 or 2. Examples include
CF.sub.2Br.sub.2, Br(CF.sub.2).sub.2Br, Br(CF.sub.2).sub.4Br,
CF.sub.2ClBr, CF.sub.3CFBrCF.sub.2Br, and the like. Further
examples of suitable chain transfer agents are disclosed in U.S.
Pat. No. 4,000,356.
[0064] Suitable organic peroxides are those which generate free
radicals at curing temperatures. A dialkyl peroxide or a
bis(dialkyl peroxide) which decomposes at a temperature above
50.degree. C. is especially preferred. In many cases it is
preferred to use a di-tertiarybutyl peroxide having a tertiary
carbon atom attached to peroxy oxygen. Among the most useful
peroxides of this type are 2,5-dimethyl-2,5-di(tertiarybu-
tylperoxy)hexyne-3 and
2,5-dimethyl-2,5-di(tertiarybutylperoxy)hexane. Other peroxides can
be selected from such compounds as dicumyl peroxide, dibenzoyl
peroxide, tertiarybutyl perbenzoate, .alpha.,.alpha.'-bis(t-but-
ylperoxy-diisopropylbenzene), and
di[1,3-dimethyl-3-(t-butylperoxy)-butyl]- carbonate. Generally,
about 1-3 parts of peroxide per 100 parts of fluoropolymer is
used.
[0065] Another component which is usually included in a cure
composition based on an organic peroxide, is a coagent composed of
a polyunsaturated compound which is capable of cooperating with the
peroxide to provide a useful cure. These coagents can be added in
an amount equal to 0.1 and 10 parts per hundred parts
fluoropolymer, preferably between 2 to 5 parts per hundred parts
fluoropolymer. Examples of useful coagents include triallyl
cyanurate; triallyl isocyanurate; triallyl trimellitate;
tri(methylallyl) isocyanurate; tris(diallylamine)-s-triazine;
triallyl phosphite; N,N-diallyl acrylamide; hexaallyl
phosphoramide; N,N,N',N'-tetraalkyl tetraphthalamide;
N,N,N',N'-tetraallyl malonamide; trivinyl isocyanurate;
2,4,6-trivinyl methyltrisiloxane; N,N'-m-phenylenebismaleimide;
diallyl-phthalate and tri(5-norbornene-2-methylene)cyanurate.
Particularly useful is triallyl isocyanurate. Other useful coagents
include the bis-olefins disclosed in EPA 0 661 304 A1, EPA 0 784
064 A1 and EPA 0 769 521 A1.
[0066] According to a further embodiment, the curing of the
fluoropolymer may be effected using a polyhydroxy compound and the
cure composition will thus comprise a polyhydroxy compound. The
advantage of using a polyhydroxy compound for curing the
fluoropolymer is that it will not be necessary to include special
cure site components in the fluoropolymer. In addition to the
polyhydroxy compound, a polyhydroxy curing system generally also
comprises one or more organo-onium accelerators in addition to the
polyhydroxy compound. The organo-onium compounds useful in the
present invention typically contain at least one heteroatom, i.e.,
a non-carbon atom such as N, P, S, O, bonded to organic or
inorganic moieties and include for example ammonium salts,
phosphonium salts and iminium salts. One class of quaternary
organo-onium compounds useful in the present invention broadly
comprises relatively positive and relatively negative ions wherein
a phosphorus, arsenic, antimony or nitrogen generally comprises the
central atom of the positive ion, and the negative ion may be an
organic or inorganic anion (e.g., halide, sulfate, acetate,
phosphate, phosphonate, hydroxide, alkoxide, phenoxide,
bisphenoxide, etc.).
[0067] Many of the organo-onium compounds useful in this invention
are described and known in the art. See, for example, U.S. Pat. No.
4,233,421 (Worm), U.S. Pat. No. 4,912,171 (Grootaert et al.), U.S.
Pat. No. 5,086,123 (Guenthner et al.), and U.S. Pat. No. 5,262,490
(Kolb et al.), U.S. Pat. No. 5,929,169, all of whose descriptions
are herein incorporated by reference. Representative examples
include the following individually listed compounds and mixtures
thereof:
[0068] triphenylbenzyl phosphonium chloride
[0069] tributylallyl phosphonium chloride
[0070] tributylbenzyl ammonium chloride
[0071] tetrabutyl ammonium bromide
[0072] triaryl sulfonium chloride
[0073] 8-benzyl-1,8-diazabicyclo [5,4,0]-7-undecenium chloride
[0074] benzyl tris(dimethylamino) phosphonium chloride
[0075] benzyl(diethylamino)diphenylphosphonium chloride
[0076] Another class of useful organo-onium compounds include those
having one or more pendent fluorinated alkyl groups. Generally, the
most useful fluorinated onium compounds are disclosed by Coggio et
al. in U.S. Pat. No. 5,591,804.
[0077] The polyhydroxy compound may be used in its free or non-salt
form or as the anionic portion of a chosen organo-onium
accelerator. The crosslinking agent may be any of those polyhydroxy
compounds known in the art to function as a crosslinking agent or
co-curative for fluoroelastomers, such as those polyhydroxy
compounds disclosed in U.S. Pat. No. 3,876,654 (Pattison), and U.S.
Pat. No. 4,233,421 (Worm). Representative aromatic polyhydroxy
compounds include any one of the following: di-, tri-, and
tetrahydroxybenzenes, naphthalenes, and anthracenes, and bisphenols
of the following formula: 4
[0078] wherein A is a difunctional aliphatic, cycloaliphatic, or
aromatic radical of 1 to 13 carbon atoms, or a thio, oxy, carbonyl,
sulfonyl, or sulfonyl radical, A is optionally substituted with at
least one chlorine or fluorine atom, x is 0 or 1, n is 1 or 2, and
any aromatic ring of the polyhydroxy compound is optionally
substituted with at least one atom of chlorine, fluorine, bromine,
or with a carboxyl or an acyl radical (e.g., --COR where R is H or
a C1 to C8 alkyl, aryl, or cycloalkyl group) or alkyl radical with,
for example, 1 to 8 carbon atoms. It will be understood from the
above bisphenol formula that the--OH groups can be attached in any
position (other than number one) in either ring. Blends of two or
more of these compounds are also used.
[0079] One of the most useful and commonly employed aromatic
polyphenols of the above formula is 4,4'-hexafluoroisopropylidenyl
bisphenol, known more commonly as bisphenol AF. The compounds
4,4'-dihydroxydiphenyl sulfone (also known as Bisphenol S) and
4,4'-isopropylidenyl bisphenol (also known as bisphenol A) are also
widely used in practice.
[0080] The cure composition based on polyhydroxy compounds may
further include an acid acceptor. Acid acceptors can be inorganic
or blends of inorganic and organic. Examples of inorganic acceptors
include magnesium oxide, lead oxide, calcium oxide, calcium
hydroxide, dibasic lead phosphite, zinc oxide, barium carbonate,
strontium hydroxide, calcium carbonate, etc. Organic acceptors
include epoxies, sodium stearate, and magnesium oxalate. The
preferred acid acceptors are magnesium oxide and calcium hydroxide.
The acid acceptors can be used singly or in combination, and
preferably are used in amounts ranging from about 2 to 25 parts per
100 parts by weight of the fluoropolymer.
[0081] In a further embodiment of the invention, the cure
composition may comprise an organic peroxide and a polyhydroxy
based cure system as described above. Such cure composition can be
used with a fluoropolymer that has a halogen capable of
participating in a peroxide cure reaction as well as with
fluoropolymers that do not contain such halogens. If the
fluoropolymer has halogens capable of participating in the peroxide
cure reaction, a cure composition having a polyhydroxy compound and
a peroxide can provide for a so called dual cure. The use of an
organic peroxide in the cure composition is particularly beneficial
if the fluoropolymer is to form a fluoroelastomer layer bonded to
another elastomer that is also formed with the use of a peroxide
cure system such as for example in case of a silicone based
elastomer.
[0082] The fluoropolymer composition for providing the
fluoropolymer layer may contain further additives, such as carbon
black, stabilizers, plasticizers, lubricants, fillers, and
processing aids typically utilized in fluoropolymer compounding can
be incorporated into the compositions of the present invention,
provided they have adequate stability for the intended service
conditions.
[0083] The fluoropolymer compositions may be prepared by mixing a
fluoropolymer, a cure composition and the organic compound having
hydride function(s) and other additives in conventional rubber
processing equipment. Such equipment includes rubber mills,
internal mixers, such as Banbury mixers, and mixing extruders.
[0084] It is further possible to prepare a premix of the
fluoropolymer composition whereby the premix comprises the
fluoropolymer and part of other components of the full composition
but not all of them. The composition of such a premix will depend
on desired stability of the premix over a desired period of
storage. For example, the premix may comprise the fluoropolymer,
the organic compound having hydride groups MH and one or more
components of a cure composition but not all of the components
necessary to obtain a curable composition. For example, in case the
cure composition comprises peroxide, it will generally be desired
to exclude the peroxide from the premix and only add the peroxide
at the time of preparing the fluoropolymer composition for
preparing the fluoropolymer layer.
[0085] In a further embodiment of the present invention, the
fluoropolymer layer may comprise a thermoplastic fluoropolymer, in
particular a melt processible thermoplastic fluoropolymer. By the
term "thermoplastic fluoropolymer" is meant a fluoropolymer that is
at least partially crystalline such that a distinct melting point,
typically 100.degree. C. or more, can be identified for example
through a DSC scan of the polymer. By the term "melt processible"
is meant that the fluoropolymer has a melt viscosity such that it
can be processed from the melt through typical melt extrusion
equipment that is available. In a particular preferred embodiment
of the present invention, the thermoplastic fluoropolymer is a
chlorine containing fluoropolymer. Such chlorine atoms may be
introduced in the fluoropolymer through copolymerization with
chlorine containing fluorinated monomers or via chain transfer
agents and/or initiator systems as described above. Alternatively
or additionally, the thermoplastic fluoropolymer may contain
bromine and/or iodine atoms which can also be introduced by
copolymerization of a bromine or iodine containing comonomer, e.g.
as listed above, or through the use of chain transfer agents and/or
initiator systems that introduce Br or I atoms. Specific examples
of thermoplastic fluoropolymers that may be used with this
invention are copolymers having the following combination of
monomers: CTFE-VDF; CTFE-TFE, CTFE-TFE-HFP, CTFE-TFE-HFP-VDF;
CTFE-TFE-HFP-VDF-PPVE, CTFE-TFE-E; bromine or chlorine containing
E-TFE copolymers and bromine or chlorine containing TFE-HFP-VDF
copolymers.
[0086] In accordance with the method of the present invention for
bonding a fluoropolymer layer to a substrate, a fluoropolymer
composition is applied to a substrate and the fluoropolymer layer
is then reacted in the presence of the organic compound having the
hydride function MH to the substrate. Typically, the organic
compound will be present in the fluoropolymer composition and the
fluoropolymer composition may also include a cure composition as
described above if an elastomeric fluoropolymer layer is desired.
Preferably, effective bonding of the fluoropolymer layer is
achieved through a participation of the organic compound in a free
radical reaction.
[0087] Thus, in an embodiment of the invention, reacting and
thereby bonding the fluoropolymer layer to the substrate is carried
out by heating the fluoropolymer layer and the substrate generally
in the presence of a compound having one or more groups capable of
participating in a free radical reaction, such as ethylenically
unsaturated groups. The compound having such groups may be present
in the substrate and/or the fluoropolymer layer. For example, a
compound having unsaturated groups may be the coagent of a peroxide
cure composition described above. Also, in case the substrate
comprises a layer of a composition that upon curing forms a
silicone rubber, the composition of this layer will typically
involve compounds having ethylenically unsaturated groups.
Generally, reacting the fluoropolymer layer to the substrate will
also involve the use of a free radical generating compound such as
for example a free radical polymerization initiator. Preferably, an
organic peroxide is used as a free radical generating compound in
particular if the fluoropolymer layer includes a peroxide cure
system as a cure composition. However, also other free radical
generating compounds can be used such as for example azo compounds.
Bonding of the fluoropolymer to the substrate may be effected by
heating the fluoropolymer layer provided on the substrate to a
temperature of 120.degree. C. to 200.degree. C. and for 1 to 120
min (preferably 140.degree. C. to 180.degree. C. and for 3 to 60
min.). The heating may further be carried out while simultaneously
applying pressure.
[0088] Reaction of the fluoropolymer layer to the substrate may
further be carried out by exposure of the fluoropolymer layer and
substrate to actinic radiation, e.g. UV radiation. For example, if
a photoinitiator is included in the substrate and/or fluoropolymer
layer, bonding may be effected through the use of UV radiation.
Substrates to which the fluoropolymer layer can be bonded include
substrates that have a layer comprising an elastomer. Suitable
elastomers include non-fluorine type of elastomers such as silicone
rubbers, acrylonitrile butadiene rubber (NBR), butadiene rubber,
chlorinated and chloro-sulfonated polyethylene rubber, chloroprene,
copolymers of ethylene and propylene (EPM) rubber, terpolymer of
ethylene, propylene, and a diene (EPDM) rubber, ethylene oxide and
chloromethyl oxirane (ECO) rubber, epichlorohydrin-ethylene
oxide-allylglycidylether terpolymer (GECO), polyisobutylene,
polyisoprene, polysulfide, polyurethane, blends of polyvinyl
chloride and NBR, styrene butadiene (SBR) rubber, ethylene-acrylate
copolymer rubber, and ethylene-vinyl acetate rubber and
thermoplastic elastomers derived from ethylene-propylene-diene
terpolymer (EPDM) and a polypropylene. Bonding of the fluoropolymer
layer to an elastomeric layer of a substrate may involve providing
the fluoropolymer layer on a layer comprising a composition that
upon curing forms the elastomeric layer. Such is particularly
preferred when bonding the fluoropolymer layer to a silicone
rubber. Further substrates include layers of fluoropolymers such as
for example fluorothermoplastics. Still further, the substrate can
be a metal substrate or a plastic substrate including for example a
non-fluorinated polymer. Examples of non-fluorinated polymers
include a polyamide, a polyolefin, a polyurethane, a polyester, a
polyimide, a polystyrene, a polycarbonate, a polyketone, a
polyurea, a polyacrylate, and a polymethylmethacrylate, or a
mixture thereof. Polyamides useful as the non-fluorinated polymeric
substrate are generally commercially available. For example,
polyamides such as any of the well-known nylons are available from
a number of sources. Particularly preferred polyamides are nylon-6,
nylon-6,6, nylon-11, and nylon-12. It should be noted that the
selection of a particular polyamide material should be based upon
the physical requirements of the particular application for the
multi-layer article. For example, nylon-6 and nylon-6,6 offer
better heat resistance properties than nylon-11 and nylon-12,
whereas nylon-11 and nylon-12 offer better chemical resistance
properties. In addition, other nylon materials such as nylon-6,12,
nylon-6,9, nylon-4, nylon-4,2, nylon-4,6, nylon-7, and nylon-8 can
be used, as well as a polymer blend of nylon 6 and polyolefin.
Useful polyolefin polymers include homopolymers of ethylene,
propylene, and the like, as well as copolymers of these monomers
with, for example, acrylic monomers and other ethylenically
unsaturated monomers such as vinyl acetate and higher
alpha-olefins. Such polymers and copolymers can be prepared by
conventional free radical polymerization or catalysis of such
ethylenically unsaturated monomers. The degree of crystallinity of
the polymer can vary. The polymer may, for example, be a
semi-crystalline high density polyethylene or can be an elastomeric
copolymer of ethylene and propylene. Carboxyl, anhydride, or imide
functionalities can be incorporated into the polymer by
polymerizing or copolymerizing functional monomers such as acrylic
acid or maleic anhydride, or by modifying the polymer after
polymerization, e.g., by grafting, by oxidation, or by forming
ionomers. Examples include acid modified ethylene acrylate
copolymers, anhydride modified ethylene vinyl acetate copolymers,
anhydride modified polyethylene polymers, and anhydride modified
polypropylene polymers.
[0089] Multi-layer articles having a fluoropolymer layer bonded to
a substrate in accordance with the invention can be produced by any
of the known methods for making multi-layer articles. For example,
the layers of the multi-layer article can be prepared in the form
of thin films or sheets and then laminated together by application
of heat, pressure, or combinations thereof to form a bonded
multi-layer article. Alternatively, each of the layers can be
co-extruded to form a multi-layer article. It is also possible to
form one or more of the individual layers by extrusion coating,
e.g., using a crosshead die. The heat and pressure of the method by
which the layers are brought together (e.g. extrusion or
lamination) can be sufficient to provide adequate adhesion between
the layers. It may, however, be desirable to further treat the
resulting article, for example, with additional heat, pressure, or
both, to enhance the bond strength between the layers. One way of
supplying additional heat when the multi-layer article is prepared
by extrusion is by delaying the cooling of the multi-layer article
at the conclusion of the extrusion process. Alternatively,
additional heat energy can be added to the multi-layer article by
laminating or extruding the layers at a temperature higher than
necessary for merely processing the components. As another
alternative, the finished multi-layer article can be held at an
elevated temperature for an extended period of time. For example,
the finished article can be placed in a separate apparatus for
elevating the temperature of the article such as an oven or heated
liquid bath. Combinations of these methods can also be used.
[0090] Several articles in which a fluoropolymer layer is bonded to
a substrate can be made according to the invention. Thus, according
to one embodiment, the article may comprise a fuser member of a
plain paper copier system. Such a fuser member may comprise a metal
core covered with a silicone elastomer that is bonded to a
fluoroelastomer fusing surface layer. Because of the use of the
organic hydride compound of the invention, firm bonding between the
fluoroelastomer and silicone layer can be obtained in such a fuser
system which may therefore be manufactured in a more convenient and
easy way without the need for intermediate adhesive layers.
According to another embodiment, a hose for use in for example a
turbo engine can be made in which a layer of fluoroelastomer,
generally as an innermost layer, is bonded to non-fluorine rubber,
in particular a silicone rubber.
[0091] According to a further embodiment, a fluoropolymer layer
comprising a thermoplastic fluoropolymer may be bonded to an
elastomer. Such layers of thermoplastic fluoropolymer generally
represent effective barriers against solvents and fuels.
Preferably, the thermoplastic fluoropolymer is a fluoropolymer that
is halogenated with one or more halogens selected from chlorine,
bromine and iodine. Examples of such thermoplastic fluoropolymers
have been described above. By bonding such a thermoplastic
fluoropolymer layer to an elastomer, fuel management systems
including in particular fuel hoses can be obtained that have a high
level of impermeability thereby minimizing escape of fuel from a
fuel system. The thermoplastic fluoropolymer layer can be
effectively bonded to a layer of elastomer that is based on
fluoropolymers as well as a layer of elastomer that is based on
non-fluorine containing polymers. The thermoplastic fluoropolymer
layer may also be bonded to a non-fluorinated polymeric
substrate.
[0092] When bonding the thermoplastic fluoropolymer layer to an
elastomer layer or other polymeric substrate, the organic compound
having a hydride function MH may be included in the fluoropolymer
layer having the thermoplastic fluoropolymer and/or in the
elastomer layer or polymeric substrate. In particular, if the
elastomer layer is based on an amorphous fluoropolymer, the organic
compound may conveniently be included in the elastomer layer.
[0093] Several layer arrangements of the fuel management system can
be contemplated and used. For example, the thermoplastic
fluoropolymer layer may be provided as an innermost layer or
outermost layer in a bilayer construction. Alternatively, a
multilayer arrangement can be used in which the thermoplastic
fluoropolymer layer is provided between two layers. For example, a
fluoroelastomer layer can be used as an innermost elastomer layer
and the outermost layer can be a non-fluorinated polymer layer
including a non-fluorine type of elastomer. In such a multilayer
construction, the thermoplastic fluoropolymer layer can be
effectively bonded to both layers as a result of the presence of
the organic compound having a hydride function MH. Preferably, in
the latter arrangement, the organic compound would be contained in
the thermoplastic fluoropolymer layer.
[0094] FIG. 1 and FIG. 2 further illustrate an article according to
this invention in the form of a tube or hose, for example, a hose
suitable for use as a fuel line or turbo charger compressed air
line in an automobile system. Referring to FIG. 1, there is shown a
two-layer article 10 that includes a relatively thick outer layer
16 bonded to an inner layer 14. Outer layer 16 can be the
non-fluorinated polymer layer, as described above, and is designed
to provide article 10 with structural integrity. Outer layer 16
forms outer surface 18 of the hose. The non-fluorinated polymer can
include an elastomer (e.g., silicone rubber, ethylene acrylic
rubber, and the like) and a plastic (e.g., polyamide). Inner layer
14 is a fluoropolymer. Inner layer 14 forms inner surface 12 of the
hose. Inner layer 14 imparts chemical and thermal stability to the
hose. Inner layer 14 also serves as a barrier or protective layer
for outer layer 16 protecting it from solvent, oil or fuel. Because
of solvent and permeation resistance of fluoropolymer, inner layer
14 improves the sealing properties preventing leaking at the ends
of the hose. Some or all of the layers can include an additive to
render them electrically conductive. To further enhance structural
integrity, reinforcing aids such as fibers, mesh, braid, and/or a
wire screen can be incorporated in article 10, e.g., as separate
layers or as part of an existing layer.
[0095] Referring to FIG. 2, there is shown a three-layer article 20
that includes a relatively thick outer layer 28 bonded to an
intermediate layer 26, which is bonded to a thinner inner layer 24.
Outer layer 28 can be the non-fluorinated polymer layer, as
described above, and is designed to provide article 20 with
structural integrity. Outer layer 28 forms outer surface 30 of the
hose. The non-fluorinated polymer can include an elastomer (e.g.,
nitrile rubber, epichlorohydrin rubber, and the like), which can
improve the sealing properties of the article when the hose or tube
is attached to a rigid connector. Inner layer 24 is a
fluoroelastomer. Inner layer 24 forms inner surface 22 of the hose.
Inner layer 24 imparts chemical and thermal stability to the hose.
Because of solvent and permeation resistance of fluoropolymer,
inner layer 24 improves the sealing properties preventing leaking
at the ends. Intermediate layer 26 can be a barrier layer, which
can decrease vapor or gas penetration through the wall of the hose
when the hose is carrying, for example, a volatile organic solvent.
The combination of inner layer 24 and intermediate layer 26
minimizes the total amount of permeation from the hose and
connections within a system. Some or all of the layers can include
an additive to render them electrically conductive. To further
enhance structural integrity, reinforcing aids such as fibers,
mesh, braid, and/or a wire screen can be incorporated in article
20, e.g., as separate layers or as part of an existing layer.
[0096] The invention will now be described with reference to the
following examples without however the intention to limit the
invention thereto. All parts are by weight unless indicated
otherwise.
EXAMPLES
[0097] Abbreviations
[0098] Fluoroelastomer 1: TFE/HFP/VDF terpolymer, further
containing minor amounts of units derived from
4-bromo-3,3,4,4-tetrafluoro butene.
[0099] Fluoroelastomer 2: bisphenol curable TFE/HFP/VDF
terpolymer
[0100] FLS-2650: peroxide curable TFE/HFP/VDF terpolymer, available
from Dyneon
[0101] Fluoroplastic A: Aclar.RTM. 33C, a copolymer of CTFE and
VDF, available from Honeywell
[0102] Fluoroplastic B: Aclar.RTM. 22C, a copolymer of CTFE and
VDF, available from Honeywell
[0103] TFE: tetrafluoroethylene
[0104] VDF: vinylidene fluoride
[0105] HFP: hexafluoropropylene
[0106] CTFE: chlorotrifluoroethylene
[0107] Ca(OH).sub.2: calcium hydroxide, Rhenofit CF, available from
Rhein Chemie.
[0108] Carnauba wax: Flora.TM. 202, available from Int. Wax &
Refining Co
[0109] Trigonox.TM. 101 45B pd: organic peroxide, available from
AKZO
[0110] Perkalink.TM. 301-50: triallyl-isocyanurate, 50% on silicate
carrier, available from Akzo
[0111] TAIC: triallyl-isocyanurate, available from Nippon Kasei
[0112] Varox.RTM.t DBPH50: 45%
2,5-dimethyl-2,5-di(t-butylperoxy)-hexan and 5% di-t-butyl
peroxide, available from R. T. Vanderbilt
[0113] CaO: calcium oxide, Rhenofit F, available from Rhein
Chemie
[0114] N-774: Semi reinforcing furnace carbon black, available from
Degussa
[0115] N-990: carbon black, available from Cancarb
[0116] P-0660: Phenyltris(dimethylsiloxy)silane, available from
United Chemical Technologies
[0117] Elastosil.TM. 760/70 OH, extrusion grade silicone elastomer,
available from Wacker
[0118] Elastosil.TM. 401/60 S, silicone elastomer, available from
Wacker
[0119] Test Methods
[0120] Cure and Theological properties of fluoroelastomer compounds
were evaluated using the following test methods:
[0121] Cure rheology tests were run on uncured, compounded
admixtures using the Moving Die Rheometer (MDR) Model 2000E
Monsanto at 177.degree. C. on an 8 g quantity of the admixture in
accordance with ASTM D 5289-93a for a rotorless rheometer. No
preheat, an oscillator frequency of 100 cpm and a 0.5.degree. arc
were used. Minimum torque (ML), maximum torque (MH), and the
difference between MH and ML (delta torque), were reported. Also
reported were Ts2 (the time to a 2 unit rise in torque from ML;
Tc50 (the time to increase torque above ML by 50% of delta torque),
and Tc90 (the time to increase torque above ML by 90% of delta
torque), all of which were reported in minutes.
[0122] Mooney Scorch was measured according to ASTM 1664, Part C
(Measuring pre-vulcanisation characteristics), at 121.degree. C.
The minimum viscosity (Mmin) was recorded, as well as T3 (time to
scorch=Mmin+3 units) and T18 (time to cure: Mmin+18 units).
[0123] Physical property testing was obtained after
150.times.150.times.2 mm.sup.3 sheets were pressed and allowed to
vulcanise for 7 minutes at 177.degree. C. mold temperature,
followed by post-curing treatment by heating the sheets in a
circulating air oven maintained at about 200.degree. C. for 2
hours.
[0124] Tensile Strength at Break, Elongation at Break and Stress at
100% Elongation were determined using an Instron.TM. mechanical
tester with a 1 kN load cell in accordance with DIN 53504 (S2 die).
Test specimen strips (dumbbell) were cut from post-cured sheets.
All tests were run at a constant cross head displacement rate of
200 mm/min in fivefold. The values reported were averages of the
five tests. Hardness Shore A (2"), Stress at 100% Elongation,
Elongation at Break, and Tensile Strength at Break were reported in
units of Mega Pascals (MPa), %, and MPa respectively.
Examples 1 to 3 and comparative examples C-1 to C-3
[0125] In examples 1 to 3 and comparative examples C-1 to C-3,
curable fluoroelastomer compositions were made on a two-roll mill
by mixing compounds as given in table 1. The compounds are
presented in parts by weight per hundred parts by weight of
fluoroelastomer (phr) as is custom in the rubber industry. Examples
1 to 3 contained 1 phr P-0660 silane, comparative examples C-1 to
C-3 were made in the same way, but without the addition of silane.
The cure of the resulting mixtures was analysed on 8 g samples of
each mixture, using a Monsanto MDR at 177.degree. C. Press cured
sheets were prepared by pressing at 177.degree. C. and 6.9 Mpa for
6 min. The press-cured sheets were post-cured in air at about
200.degree. C. for 2 hrs. Physical property testing was performed
on press-cured and post-cured sheets; the results are recorded in
Table 2.
1TABLE 1 Composition of curable fluoroelastomer composition
Compound Ex 1 C-1 Ex 2 C-2 Ex 3 C-3 Fluoroelastomer-1 100 100 / / /
/ Fluoroelastomer-2 / / 100 100 / / FLS-2650 / / / / 100 100
Ca(OH).sub.2 5 5 5 5 5 5 Trigonox 101 45B pd 1 1 1 1 1 1 Perkalink
305-50 6 6 6 6 6 6 CaO 5 5 5 5 5 5 N-774 15 15 15 15 15 15 Carnauba
wax 0.75 0.75 0.75 0.75 0.75 0.75 Bisphenol AF 1 1 / / / / Onium*
1.5 1.5 / / / / P-0660 1 / 1 / 1 / Note: onium*:
Tributylmethoxypropyl phosphoniumchloride complex
[0126]
2TABLE 2 physical properties of fluoroelastomers Ex 1 C-1 Ex 2 C-2
Ex 3 C-3 Monsanto MDR (177.degree. C., test time: 6 min) ML (inch
.multidot. pounds) 1.1 1.7 0.8 0.8 1.9 2.0 MH (inch .multidot.
pounds) 6.0 4.9 15.3 11.4 12.9 11.5 MH-ML (inch .multidot. pounds)
4.9 3.2 14.5 10.6 11.0 9.5 Ts2 (min) 2.9 3.3 0.7 1.9 1.3 1.2 Tc50
(min) 3.4 2.6 1.1 3.0 2.3 1.9 Tc90 (min) 5.4 5.1 3.5 5.0 4.6 4.5
Mooney Scorch (@ 121.degree. C.) Mmin (inch .multidot. pounds) 38
46 56 58 T3 (min) 34 >60 47 32 T18 (min) >60 >60 >60
>60 Vulcanisate properties (press cured 7 min @ 177.degree. C.,
post cured 2 hrs @ 200.degree. C.) Hardness shore A (2") 73 73 72
72 Modulus 100% (Mpa) 7.5 3.4 4.0 4.4 Tensile (Mpa) 18.5 14.0 13.4
11.8 Elongation (%) 210 328 277 255 Die C tear (kN/m) 21 27 22
21
[0127] The results in table 2 indicate that the in all cases,
fluoroelastomers with good physical properties were obtained.
[0128] In order to evaluate the adhesion between the above
fluoroelastomers and various silicone rubbers, laminates of
fluoroelastomer/silicone rubber were made. Therefore, sheets were
made of the curable fluoroelastomer compositions of about 2 mm
thickness and of VMQ compositions of about 5-7 mm for making
silicone rubbers. From these sheets, strips were cut of about
2.5.times.7 cm. A narrow strip of PTFE film was inserted between
the curable fluoroelastomer composition and VQM strips, at an edge
for about 1.5 cm. The PTFE film did not adhere to any of the
compositions, and was used only to create two tabs for insertion
into each jaw of an adhesion testing apparatus. The lamination was
accomplished using a hot press at 177.degree. C. for 30 min. The
superposed strips of curable fluoroelastomer composition and VMQ
compounds, having a total thickness of about 7-9 mm were pressed in
a mold of 6 mm in depth. The high temperature and press assured
vulcanization and the formation of a bond between the two layers.
After cooling to room temperature for 4 hours, the laminated sheets
were cut to a width of about 1.27 to 2.54 cm. The adhesion between
the two layers was measured according to ASTM D-1876, using a
Sintech Tester 20 (available from MTS Systems Corporation), with a
cross head speed of 50 mm/min. The results, as given in table 3 are
the average values of at least three specimens.
3TABLE 3 adhesion between fluoroelastomer/silicone laminates Bond
strength (N/mm) Ex 1 C-1 Ex 2 C-2 Ex 3 C-3 VMQ A -- -- >5.7 (RT)
0 (IF) VMQ B -- -- >4.5 (RT) 0.8 (IF) VMQ C -- -- 2.6 (IF/RT) --
VMQ D 1.1 (IF) 0 (IF) >5.2 (RT) 0.8 (IF) Elastosil 5.2 RT 5.5 RT
401/60S Elastosil 5.1 RT/IF 0.7 IF 760/70 OH Notes: IF =
interfacial failure, real indication of bond strength RT = rubber
tear, indicated that the bond was stronger than the elastomer
itself. The value recorded was max value. VMQ A-D: VMQ compounds of
different composition typically used in making turbo charger hoses
Since the Elastosil .TM. samples did not contain curatives,
additional 1.5 phr Trigonox .TM. was used to make the
laminates.
[0129] The results in table 3 indicate a significant increase in
adhesion between the fluoroelastomers produced in the presence of
the silane and silicone rubbers produced from a variety of VMQ
compositions. Whereas the comparative examples did not show good
adhesion to VMQ compounds (except with Elastosil.TM. 401/60S), a
good to very strong adhesion (rubber tear) was noticed for the
fluoroelastomers produced with a silane.
Examples 4 and 5 and Comparative Examples C-4 and C-5
[0130] Fluoroelastomer compounds were made using a two roll mill by
compounding 100 parts FLS-2650, 30 parts N-990, 3 parts calcium
hydroxide (available from C. P. Hall), 2.5 parts Varox.RTM.
DBPH-50, 2.5 parts TAIC and 1 part P-0660. 10 cm.times.10 cm sheets
of about 1.5 mm thickness of curable fluoroelastomer composition
were made, adjusting the gap of the roll mill. One sheet of curable
fluoroelastomer composition was laminated against a 10 cm.times.10
cm sheet of fluoroplastic A, having a thickness of 0.05 mm (example
4) and another sheet of curable fluoroelastomer composition was
laminated against a 10 cm.times.10 cm sheet of fluoroplastic B,
having a thickness of 0.038 mm (example 5). For comparative
examples C-4 and C-5, curable fluoroelastomer compositions were
made as for examples 4 and 5, except that no P-0660 was added. The
comparative compounds were laminated against fluoroplastic A
(comparative example C-4) or against fluoroplastic B (comparative
example C-5). The laminates were made using a hot press at
177.degree. C. for 3 minutes. A 15.2 cm.times.15.2 cm shim stock
with 1.25 mm thickness was used to keep the thickness of the
laminate under the heat press. The samples were removed from the
press and allowed to cool to room temperature. The resulting
samples were cut into three 25.4 mm wide strips. Peel or adhesion
strength were measured on the three strips in accordance with ASTM
D-1876, using an Instron.TM. Model 1125 tester (available from
Instron Corp.), with a cross head speed of 100 mm/min. In order to
facilitate testing of the adhesion between the two layers, a 0.05
mm thick polyester was inserted. The results, as given in table 4
are the average values of at least three specimens (only the middle
80% of the sample was taken into account).
4TABLE 4 adhesion between fluoroelastomers and chlorine containing
fluoroplastics Example Chlorine containing Peel strength No
fluoroplastic --SiH co-agent (phr) (N/mm) 4 Fluoroplastic A 1 1.35
IF 5 Fluoroplastic B 1 1.45 IF C-4 Fluoroplastic A 0 0.12 IF C-5
Fluoroplastic B 0 0.28 IF
[0131] The data in table 4 show that substantially improved
adhesion between fluoroelastomers and chlorine containing
fluoroplastics could be obtained if a --SiH co-agent was added to
the curable fluoroelastomer composition.
* * * * *