U.S. patent application number 10/546951 was filed with the patent office on 2007-06-28 for one-part solvent-based adhesive for bonding polymer materials.
Invention is credited to Douglas H. Mowrey, Patrick A. Warren.
Application Number | 20070149665 10/546951 |
Document ID | / |
Family ID | 32908067 |
Filed Date | 2007-06-28 |
United States Patent
Application |
20070149665 |
Kind Code |
A1 |
Mowrey; Douglas H. ; et
al. |
June 28, 2007 |
One-part solvent-based adhesive for bonding polymer materials
Abstract
What is disclosed are adhesives and bonding methods employing a
single coat of a solvent-based adhesive that effectively bonds
thermoplastic polymers and especially thermoplastic elastomers. The
adhesive components are a organosilane component selected from
organosilane-isocyanate adduct and isocyanato-organosilane, a
post-chlorinated polymer containing propylene repeating units or
derivative thereof, and solvent. Also disclosed are methods for
joining a rigid, structural substrate to a molten polymer such as a
TPE via injection molding or extrusion. Durable adhesion between
the adhesive treated portion of the rigid sub-strate and the
melt-processed polymer is achieved with or without a previous heat
treatment on the adhesive-coated substrate prior to joining to the
thermoplastic melt.
Inventors: |
Mowrey; Douglas H.;
(Titusville, PA) ; Warren; Patrick A.; (Erie,
PA) |
Correspondence
Address: |
LORD CORPORATION;PATENT & LEGAL SERVICES
111 LORD DRIVE
CARY
NC
27512
US
|
Family ID: |
32908067 |
Appl. No.: |
10/546951 |
Filed: |
February 26, 2004 |
PCT Filed: |
February 26, 2004 |
PCT NO: |
PCT/US04/05806 |
371 Date: |
May 9, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10377069 |
Feb 28, 2003 |
6878231 |
|
|
10546951 |
May 9, 2006 |
|
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Current U.S.
Class: |
524/262 ;
524/543; 524/571 |
Current CPC
Class: |
C09J 123/28 20130101;
C08G 18/809 20130101; C08K 5/544 20130101 |
Class at
Publication: |
524/262 ;
524/543; 524/571 |
International
Class: |
C08K 5/24 20060101
C08K005/24 |
Claims
1. A liquid adhesive comprising an organosilane-containing
component selected from the group consisting of a
organosilane-isocyanate adduct and an isocyanato-organosilane, a
polymer comprising post-chlorinated propylene repeating units, and
an organic solvent.
2. The adhesive according to claim 1 wherein said polymer has a
weight average molecular weight of from 5,000 to 60,000 and a
chlorine content of from 10 wt. % to 60 wt. %.
3. The adhesive according to claim 1 wherein said polymer is
selected from crystalline polypropylene, noncrystalline
polypropylene, ethylene-propylene copolymer,
ethylene-propylene-diene copolymer, and
propylene-C.sub.4-C.sub.10-.alpha.-olefin copolymer.
4. The adhesive according to claim 1 wherein said post-chlorinated
polymer is maleated.
5. The adhesive according to claim 1 wherein said organic solvent
is selected from the group consisting of aromatic and halogenated
aromatic hydrocarbons.
6. The adhesive according to claim 1 having a total solids content
of from 5 to 50 wt. %.
7. The adhesive according to claim 1 wherein said
organosilane-containing component is a organosilane-isocyanate
adduct containing the linkage --NH--C(O)-A-R--Si, wherein A is O,
S, or N, and R is a divalent C.sub.1-C.sub.20 hydrocarbyl
group.
8. The adhesive according to claim 1 wherein the
organosilane-containing component is an isocyanatosilane containing
at least one hydrolyzable group and at one free isocyanate group
and having the structure (E) ##STR7## wherein R.sup.1 is a
monovalent aliphatic, cycloaliphatic or aromatic radical having
from 1 to 20 carbon atoms; R.sup.2 is a monovalent aliphatic,
cycloaliphatic or aromatic organic radical containing from 1 to 8
carbon atoms, --R.sup.3--O--R.sup.4, and ##STR8## where R.sup.3 is
an alkylene group having from 1 to 4 carbon atoms and R.sup.4 is an
alkyl group having from 1 to 4 carbon atoms; a is zero or 1, and Z
is a divalent organic radical attached to the silicon atom via a
carbon-silicon bond.
9. A method for joining a polymer extrudate to a continuous or
elongated structural member which has been treated with the
adhesive of claim 1 comprising passing the adhesive-treated
substrate adjacent to or through an extruder die, and joining the
member to the extrudate to form a joined article, and cooling the
joined article.
10. The method of claim 9 wherein said joined article is a window
channel.
11. A method for joining an injection molded polymer to a
structural member which has been treated with the adhesive of claim
1, comprising inserting the adhesive-treated member into an
injection mold cavity adapted to receive the member, exposing an
adhesive-treated surface of the member to the mold cavity,
injecting said polymer into the cavity contacting the polymer with
the treated surface of the member, and cooling the polymer.
Description
FIELD OF THE INVENTION
[0001] The invention pertains to solvent-based polymer-bonding
adhesives, such as thermoplastic elastomers and elastomer
vulcanizates to similar or dissimilar substrates. The adhesives
employ a silane-containing component and a chlorinated polymer.
BACKGROUND OF THE INVENTION
[0002] It is well known that thermoplastic articles formed from a
variety of polyolefin-containing plastic materials have widely
varying surface properties, including surface tension, roughness
and flexibility. As substrates used in forming a bonded composite,
achieving durability, i.e., environmentally-resistant bonding has
been a continuing challenge. There are many known adhesion
promoters used as tie-coats, or primers for paints on
polyolefin-based materials. Applying a tie coat is normally an
added step in the coating process. The adhesion promoter is usually
applied in a thin layer, normally about 6 to 10 microns
(.mu.m).
[0003] Known adhesion promoters for coatings olefin-based
thermoplastic surfaces contain chlorinated polyolefins, some
examples of which are described in U.S. Pat. Nos. 4,997,882;
5,319,032 and 5,397,602. Others include carboxy-modified
polyolefins. See U.S. Pat. No. 4,299,754 teaching
carboxylate-modified polyolefins in aromatic or aliphatic
hydrocarbon or a chlorinated hydrocarbon.
[0004] Performance obtained with chlorinated polyolefin in
tie-layers for coatings is not predictive for bonding of
olefin-based articles to substrates typically encountered, such as
steel and aluminum. This is demonstrated in an article in the
Journal of Coating Technology, 65, No. 827 p. 21 (1993) for
chlorinated polyolefins.
[0005] In the case of bonding rigid substrates in-line to a molten
olefin-based thermoplastic profile or in insert-injection molding,
temperatures above the processing temperature or heat dwell times
must be avoided. Melt-processible thermoplastic elastomers, or
TPE's, TPV's, TPO's (hereinafter collectively, "TPE") are desirable
materials for forming such products as window channels,
weatherstrips, and various automobile trim pieces. A rigid,
structural substrate such as metal or rigid thermoplastic is joined
in-line to the molten profile. In similar fashion, there are known
methods where a rigidifying substrate and TPE are joined by insert
injection molding. Improved adhesion between the substrate and TPE
is desired.
[0006] U.S. Pat. No. 5,051,474 to Warren, et al discloses adhesives
comprising a linear polyester polyurethane, a halogenated
polyolefin, a phenolic resin, and a cross-linker. The formulation
is preferably utilized as a two-component adhesive for bonding
polymer blend-based thermoplastic elastomers to various substrates
such as metal.
[0007] U.S. Pat. No 5,268,404 to Mowrey discloses a one-part
adhesive composition exhibiting strong rubber-to-metal bonds with
excellent environmental resistance without the necessity of first
priming the metal surface. The composition comprises a halogenated
polyolefin, an aromatic nitroso compound, metal oxide such as zinc
oxide or magnesium oxide, and optionally a vulcanizing agent such
as sulfur or selenium, a phenolic epoxy resin, or carbon black.
[0008] U.S. Pat. No. 5,432,246 to Fenn et al. discloses a silane
oligomer made from a secondary amino-alkoxy silane, a
polyisocyanate and optionally a single isocyanate group, resulting
in a substituted urea, with no free remaining isocyanate
groups.
[0009] U.S. Pat. No. 6,512,039 to Mowrey discloses an adhesive
designed to bond metal to peroxide cured elastomers. A
representative formulation comprises from 10 to 20% of
chlorosulfonated polyethylene, from 15-25% of an acid scavenger,
from 35-45% of a polymaleimide, from 5-15% of precipitated silica,
and 10-20% of an isocyanatosilane.
[0010] EP 0187171 discloses primers for thermoplastic polyolefins.
Representative of these primer is a composition comprising
chlorinated polyolefin, such as polypropylene, or graft-modified
polypropylene, a crosslinkable binder and a crosslinking agent
selected from amines, amidoamines, isocyanates, poly-isocyanates,
cyanurates, and acrylates containing --OH or --COOH groups.
[0011] Representative adhesives containing polyisocyanates, or
bonding agents such as aminosilanes are known. U.S. Pat. No.
4,031,120 (Lord) discloses one-coat adhesives based on
isocyanatosilane or an isocyanate-organosilane adduct. A variety of
film formers are suggested. Optimally, the adhesive includes a
nitroso compound. It would be industrially important to provide
good primary adhesion bonding of a one-coat adhesive to more than
one type of TPE under conditions of limited heat, such as extrusion
bonding or cladding, or insert injection molding.
SUMMARY OF THE INVENTION
[0012] In one aspect the invention provides a method for bonding a
TPE to a substrate by employing a single coat, liquid,
solvent-based adhesive which comprises an organosilane component
selected from organosilane-isocyanate adduct (A) or
isocyanato-organosilane (B), and a post-chlorinated polymer
comprising propylene repeating units. The typical nonvolatile
component amounts are 10 to 90 wt. % of the organosilane component
and 90 to 10 wt. % of post-chlorinated polymer and an overall
solids content range of 5 to 50 wt. % in organic solvent.
[0013] In a method aspect, the invention includes a method of
bonding a rigid, structural substrate to a molten polymer
comprising contacting a molten polymer extrudate with a treated
substrate. The substrate is treated by applying adhesive to the
substrate, and drying. Another method aspect is a method for
bonding a polymer injection melt which comprises contacting the
injection melt to a treated substrate contained in the injection
mold. The substrate is treated by applying adhesive and drying.
After contacting the injection melt to the adhesive-treated portion
of the substrate, the composite is cooled, and removed from the
mold. Durable adhesion between the adhesive treated portion of the
inserted rigid substrate and the melt-processed polymer is achieved
with or without a heat treatment applied to the adhesive-coated
substrate prior to joining to the TPE.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0014] The polymeric film former employs a base polymer which is
post-chlorinated polypropylene (CPP). The base polymer comprises
propylene repeating units. The film former can encompass
derivatives of post-chlorinated polypropylene. The base polymer
weight average molecular weight is from 5,000 to 60,000, and
preferably from 15,000 to 45,000. The chlorine content should be in
the range of 10 to 60 weight %, and preferably chlorine content is
from 20-50 weight %. As the base polymer comprising propylene
repeating units, these include crystalline polypropylene,
noncrystalline polypropylene, ethylene-propylene copolymer,
ethylene-propylene-diene copolymer, propylene-
C.sub.4-C.sub.10-.alpha.-olefin copolymer may be used. The base
polymer may actually be a blend of polypropylene homopolymer and a
copolymer comprising propylene repeating units may also be used. As
an example of a blend, 25 to 95 wt. % of a propylene homopolymer is
combined with from 5 to 75 wt %, preferably 10 to 60 wt. % of a
random propylene copolymer containing repeating units based on
1-butene, 1-pentene, 1-hexene, 1-heptene, or 1-octene. Most
preferred is chlorinated polypropylene available commercially under
the Hardlen.RTM. designation. Examples include Hardlen 13-LP
chlorinated polypropylene from Toyo Kasei Kogyo Co., Ltd., and
products under the Eastman CP-343-1 and CP-343-3 designations.
[0015] Many suitable derivatives of chlorinated polypropylene
useful herein are known. Such a representative derivative is a
polymer comprising propylene repeating units which is modified by
incorporating one or more ethylenic unsaturated monomers, e.g.,
acrylate or methacrylate monomers, macromonomers, vinyl-functional
organosilanes, liquid terminal ethylenic polydiene polymers and/or
other graft-functional materials such as maleic acid anhydride, or
maleimides. These are typically introduced into solution with
chlorinated polypropylene, as taught in Japanese Kokai No. 24316
(1976), No. 36128 (1982), No. 215667 (1986), US 4,608,415 and US
5,130,373. The starting CPP material is for example Hardlen.RTM.
14-LLB manufactured by Toyo Kasei Kogyo Co., Ltd. of weight average
molecular weight about 30,000, a chlorine content 27%, as a 30%
solution in toluene. Up to 40 wt. parts total of monomers, and/or
macromonomers and/or liquid polymers, etc., are present with 100
wt. parts of CPP in a peroxide-initiated reaction in solution of
organic solvent. In another chlorinated polypropylene derivative,
chlorinated polypropylene is derivatized ("maleated") with 0.1 to
10 wt. "phr" (parts per hundred CPP) of maleic acid anhydride
according to known methods. As a further alternative derivative,
maleic acid anhydride and acryl- or methacryl-modified hydrogenated
polybutadiene, are incorporated using peroxide under known
conditions.
[0016] As preferred derivatives of chlorinated polypropylene there
are included maleic anhydride modified, or maleated chlorinated
polypropylene. An exemplary maleic anhydride derivative can be
prepared by combining 100 wt. parts of chlorinated polypropylene
having a chlorine content, for example of 30% with 10 wt. parts of
maleic anhydride and 300 parts of chlorobenzene in a reactor
equipped with a reflux condenser, and dissolving by heating at
110.degree. C. To this solution, 10 wt. parts of benzoyl peroxide
are added thereto over a 6-hour period of addition. After
completion of the addition, the mixture is allowed to further react
under agitation for 3 hours at the same temperature. After the
reaction is completed, chlorobenzene and unreacted maleic anhydride
are distilled off under atmospheric pressure followed by vacuum
stripping at 1 mm Hg at 140.degree. C. The bound maleic anhydride
content of chlorinated polypropylene is about 8 wt. %, and the
bonded chlorine content is about 27%. This derivative is readily
taken up in the solvent used for formulating the adhesive having a
typical solids range of 5 to 25 wt. %. Commercially available
derivatives of chlorinated polypropylene modified with maleic
anhydride include CP 343-1, from Eastman Chemical Company,
Kingsport Tenn., HARDLEN.RTM. CY-9122P, from Toyo Kasei Kogyo,
Ltd., Osaka, Japan, and HYPALON.RTM. CP-826, available from DuPont
Dow Elastomers L.L.C., Wilmington, Del.
[0017] Specific exemplary derivatizing agents for CPP include
liquid type polybutadiene number average molecular weight 500 to
5000, acrylic acid oligomer having a hydroxyl value of 95,
molecular weight 570, a styrene/acrylonitile macromonomer having a
terminal methacryloyl radical, isobutyl methacrylate macromonomer
having a terminal methacryloyl radical, with molecular weight 6000,
and 2-ethylhexylcarylate. The acrylic, maleic- or
methacrylic-modified polybutadienes useful for derivatizing are
known and made according to known methods such as by esterification
reaction of hydrogenated OH-terminal polybutadiene to acrylic acid
or methacrylic acid, (ii) by an addition reaction of the
diisocyanate-hydroxyacrylate or hydroxymethacrylate prepolymer to
OH-polybutadiene, (iii) by a ring-opening esterification reaction
of hydrogenated polybutadiene containing a carboxyl group to
glycidyl acrylate or glycidyl methacrylate, (iv) by an addition
reaction of iminolacrylate or iminolmethacrylate to hydrogenated
polybutadiene containing a carboxyl group, or (v) by the Ene
reaction. Likewise, other suitable chlorinated polypropylene
derivatives can be prepared using known polyolefin modifying agents
containing functional groups such as sulfonate groups, carboxylic
acid anhydride groups, hydroxyl groups, epoxide groups, carboxylic
acid ester groups, carboxylic acid amide groups, carboxylic acid
groups, and the like can be reacted with chlorinated
polypropylene.
[0018] The adhesive compositions of this invention are prepared by
conventional mixing in one or more organic solvents. For ease of
application, as is conventional in this art, the components are
mixed and dispersed in inert organic liquid diluents which are the
primary carrier of the homogeneous, refined mixture of solids, and
once the wet adhesive composition has been applied, the carrier is
readily removed by evaporation. Examples of suitable organic
solvents are, aromatic and halogenated aromatic hydrocarbons such
as benzene, toluene, xylene, chlorobenzene, dichlorobenzene, and
the like; halogenated aliphatic hydrocarbons such as
trichloroethylene, perchloroethylene, propylene dichloride and the
like; ketones such as methyl ethyl ketone, methyl isobutyl ketone,
and the like; ethers, naphthas, etc., including mixtures of such
carriers. Preferred organic solvents are xylene and toluene, ortho-
and para-chlorotoluene, optionally in combination with
tetrachloroethylene. The amount of solvent employed is that which
provides a composition suitable for use as an easily applied
adhesive and ordinarily such as to provide a total solids content
(TSC) ranging from about 5 to 50 wt. %, preferably about 10 to
about 30 wt. %, and more preferredly 10 to 20 wt. %.
[0019] Isocyanatosilane adducts are prepared by effecting a
reaction between a co-reactive organosilane and a polyisocyanate by
adding the organosilane, preferably as a dilute solution, to the
polyisocyanate, also preferably diluted, at a temperature in the
range from about 10.degree. to about 100.degree. C., while
agitating the mixture by a mechanical stirrer or similar device. A
stoichiometric amount of equivalents of isocyanate groups in the
polyisocyanate can be reacted with co-reactive groups of the
organosilane, or preferably, a stoichiometric excess of isocyanate
groups to co-reactive organosilane is used. While not essential, a
suitable catalyst, e.g., dibutyltin dilaurate, can be employed. The
reaction readily proceeds when catalyst is employed, and is mildly
exothermic
[0020] In one embodiment the organosilane-containing component is
an adduct (A) of an isocyanate-reactive organosilane and a molar
excess of polyisocyanate that is co-reactive therewith
("organosilane-isocyanate adduct"). The organosilane is coupled
through a functional hydrocarbyl group bonded directly to the
silicon. This linkage can be represented in abbreviated fashion as
--NH--C(O)--A-R--Si, wherein representative groups A include O, S,
>N--, and R is a divalent hydrocarbyl C.sub.1-C.sub.20 group,
especially C.sub.2-C.sub.4. Isocyanate-organosilane adducts are
taught in U.S. Pat. No. 4,031,120, and prepared by reacting a
multifunctional organosilane and a polyisocyanate, in dilute
solution, conducted at a temperature in the range from about
10.degree. C. to about 100.degree. C. while agitating the mixture
by a mechanical stirrer or similar device. An optional conventional
catalyst, such as dibutyltin dilaurate, can be employed. The
reaction is instantaneous and exothermic when catalysts are
employed. It is most preferred that the amount of polyisocyanate
present during the reaction be such as to ensure obtaining an
resulting adduct having at least one free isocyanate group.
[0021] A specific illustration of an isocyanate-organosilane adduct
is disclosed in U.S. Pat. No. 5,623,044 and is the reaction product
of a secondary aminoalkoxy silane and a polyisocyanate. As an
example, 485 g of HDl (Desmodur N-100 ex. Mobay) (2.59 equivalents)
and 225 g of alkyl phthalate are charged to a resin kettle equipped
with a mechanical agitator, a thermometer, a N.sub.2 inlet adapter
and an addition funnel. The mixture is thoroughly mixed and purged
under N.sub.2 blanket. About 300 g of silane
(N,N-bis[(3-trimethoxysilyl)-propyl]amine) (0.88 equivalents) is
slowly added to the mixture. The resulting adduct has an isocyanate
content of 7.0%.
[0022] Representative isocyanate-reactive organofunctional silanes
suitable for making an adduct with a polyisocyanate include without
limitation the known silanes that contain an abstractible hydrogen,
such as amino, mercapto, and hydroxy groups, ----COOH, ----NH----,
----CONH.sub.2, ----CONH---- including polyols, polyamines,
polymercaptans and polyacids. Examples of starting silanes are
N,N-bis[(3 -triethoxysilyl)propyl]amine;
N,N-bis[(3-tripropoxysilyl)propyl]amine;
N-(3-trimethoxysilyl)propyl-3-[N-(3
-trimethoxysilyl)-propylamino]propionamide;
N-(3-triethoxysilyl)propyl-3-[N-3-triethoxysilyl)-propylamino]propionamid-
e;
N-(3-trimethoxysilyl)propyl-3-[N-3-triethoxysilyl)-propylamino]propiona-
mide; 3-trimethoxysilylpropyl
3-[N-(3-trimethoxysilyl)-propylamino]-2-methyl propionate;
3-triethoxysilylpropyl 3-[N-(3-triethoxysilyl)propylamino]-2-methyl
propionate; 3-trimethoxysilylpropyl 3-[N-(3-triethoxysilyl)
-propylamino]-2-methyl propionate; and the like. A commercial
example silane is gamma-mercaptopropyl-trimethoxysilane (available
as A189 from Union Carbide) or N,N'-bis((3-trimethoxysilyl)propyl)
amine.
[0023] Aminofunctional organosilanes are most preferred and include
but are not limited to aminofunctonal organosilanes having the
structure (A) ##STR1## wherein R, R.sup.1, R.sup.2, and "a" are as
previously defined for structure (A); and R.sup.5 is selected from
the group consisting of hydrogen, monovalent aliphatic radicals
having from 1 to 8 carbon atoms, monovalent cycloaliphatic radicals
having from 4 to 7 ring carbon atoms, phenyl, alkaryl radicals
having 6 nuclear carbon atoms and containing one or more
substituent alkyl groups having from 1 to 4 carbon atoms, and
--R.sup.6--NH--R.sup.7, wherein R.sup.6 is selected from the group
consisting of divalent aliphatic, cycloaliphatic and aromatic
radicals having from 1 to 20 carbons, there being preferably at
least two carbon atoms separating any pair of nitrogen atoms, with
R.sup.6 being preferably an alkylene group of 2 to 9 carbon atoms;
and R.sup.7 being the same as R.sup.5 and preferably is hydrogen.
Specific representative isocyanate-reactive organosilanes, where
"g" and "d" represent gamma and delta, respectively, are
hydroxypropyltrimethoxysilane, hydroxypropyltriethoxysilane,
hydroxybutyltrimethoxysilane, g-aminopropyltrimethoxysilane
g-aminopropyltriethoxysilane, methylaminopropyltrimethoxysilane,
g-aminopropyltripropoxysilane, g-aminoisobutyltriethoxysilane,
g-aminopropylmethyldiethoxysilane,
g-aminopropylethyldiethoxysilane,
g-aminopropylphenyldiethoxysilane, d-aminobutyltriethoxysilane,
d-aminobutylmethyldiethoxysilane, d-aminobutylethyldiethoxysilane,
g-aminoisobutylmethyldiethoxysilane,
N-methyl-g-aminopropyltriethoxysilane,
N-phenyl-g-aminoisobutylmethyldieth oxysilane,
N-ethyl-d-aminobutyltriethoxysilane,
N-g-aminopropyl-g-aminopropyltriethoxysilane,
N-.beta.-aminoethyl-g-aminoisobutyltriethoxysilane,
N-g-aminopropyl-d-aminobutyltriethoxysilane,
N-aminohexyl-g-aminoisobutylmethyidiethoxysilane,
methylaminopropyltriethoxysilane,
g-aminopropylmethoxydiethoxysilane, and the like. Examples of
commercially available amino-functional organosilanes include
Silquest.TM. Y-9669, N-phenyl-gamma-aminopropyltrimethoxysilane,
Silquest.TM. A1170, bis-(g-trimethoxysilylpropyl)amine,
Silquest.TM. A1100, g-aminopropyltriethoxysilane, Silquest.TM.
A1110, g-aminopropyltrimethoxysilane, and Silquest.TM. A1120,
N-(.beta.-aminoethyl)-gamma-aminopropyltrimethoxysilane, available
from OSI, Inc.
[0024] Representative hydroxyl group-containing organosilanes
include but are not limited to compounds of the general structure
B: ##STR2## wherein R is a divalent aliphatic, cycloaliphatic or
aromatic saturated or unsaturated radical having from 1 to 20
carbon atoms, and is preferably an alkylene radical having from 1
to 9, most preferably 2 to 4, carbon atoms; R.sup.1 is a monovalent
aliphatic, cycloaliphatic or aromatic radical having from 1 to 20
carbon atoms, and is preferably selected from the group consisting
of alkyl radicals having from 1 to 4 carbon atoms, cycloalkyl
radicals having from 4 to 7 ring carbon atoms, and aryl radicals
having 6, 10, or 14 nuclear carbon atoms, and including such aryl
radicals containing one or more substituent alkyl groups having
from 1 to 4 carbon atoms; R.sup.2 is a monovalent aliphatic,
cycloaliphatic or aromatic organic radical containing from 1 to 8
carbon atoms, and is preferably selected from the group consisting
of alkyl radicals having from 1 to 4 carbon atoms,
R.sup.3--O--R.sup.4, and ##STR3## where R.sup.3 is an alkylene
group having from 1 to 4 carbon atoms (methyl, ethyl, propyl,
butyl) and R.sup.4 is an alkyl group having from 1 to 4 carbon
atoms; and a is zero or 1, preferably zero;
[0025] Representative mercaptofunctional silanes reactive with
polyisocyanates include but are not limited to those having the
structure (C) ##STR4## wherein R, R.sup.1, R.sup.2 and "a" are as
previously defined for structures A or B; Commercially available
mercaptosilane is sold by OSI as SILQUEST A-189,
mercaptopropyltrimethoxysilane.
[0026] The preferred starting material organosilane comprises a
single organic chain having from 1 to 20 carbon atoms bonded to
silicon, said chain having at least one extractable hydrogen atom,
said extractable hydrogen atom preferably being attached to a
functional group separated from the silicon atom by at least 3
interconnected carbon atoms. The active hydrogen moiety is in any
position in the molecule whereby this group displays significant
activity according to the Zerewitnoff test described by Wohler in
the Journal of the American Chemical Society, Vol. 49, p. 3181
(1927).
[0027] Starting polyisocyanates for making isocyanate-organosilane
adducts (A) can be aliphatic aliphatic, cycloaliphatic,
arylaliphatic, heterocyclic or aromatic polyisocyanate, or mixtures
thereof, with an average isocyanate functionality of at least about
2.0 and an equivalent weight of at least about 80. Preferably, the
isocyanate functionality of the polyisocyanate is at least about
2.0, more preferably at least about 2.2, and is more preferably at
least about 2.3; and is preferably no greater than about 4.0, more
preferably no greater than about 3.5, and is most preferably no
greater than about 3.0. Examples of useful diisocyanates include
2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate (TDI),
diphenylmethane 4,4'-diisocyanate (MDI), 1,4-phenylene
diisocyanate, dicyclohexylmethane diisocyanate (H.sub.12-MDI),
isophorone diisocyanate (IPDI), 1,6-hexanediisocyanate, and
1,3-(.alpha.,.alpha.,.alpha.',.alpha.'-tetramethyl)xylylene
diisocyanate (TMXDI) 2,2,4-trimethylhexamethylene-1,6-diisocyanate;
hexamethylene-1,6-diisocyanate, diphenylmethane-4,4'-diisocyanate,
triphenylmethane-4, 4'4-triisocyanate,
3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate,
polymethylene polyphenylisocyanate, m-phenylenediisocyanate,
p-phenylenediisocyanate, 2,6-tolylene diisocyanate,
1,5-naphthalenediisocyanate, naphthalene-1,4-diisocyanate,
diphenylene-4,4'-diisocyanate, 3,3'-bi-tolylene-4,4'-diisocyanate,
ethylene diisocyanate, propylene-1,2-diisocyanate,
butylene-2,3-diisocyanate, ethylidenediisocyanate,
butylidenediisocyanate, xylylene-1,4-diisocyanate,
xylylene-1,3-diisocyanate, methylcyclohexyldiisocyanate,
cyclopentylene-1,3-diisocyanate, cyclohexylene-1,4-diisocyanate,
4,4'-methylene-bis(cyclohexylisocyanate),
p-phenylene-2,2'-bis(ethylisocyanate), 4,4'-diphenylene
ether-2,2'-bis(ethylisocyanate), tris(2,2',2''-ethylisocyanate
benzene), 5-chloro-phenylene-1,3-bis(propyl-3-isocyanate),
5-methoxy-phenylene-1,3-bis(propyl-3-isocyanate),
5-cyanophenylene-1,3-bis(propyl-3-isocyanate),
4-methyl-phenylene-1,3-bis(propyl-3-isocyanate), and the like.
Polyisocyanates can be formed as dimers, trimers, tetramers and the
like using customary and known, suitable catalysts. In an oligomer,
free isocyanate groups may be present along with uretdione, biuret,
isocyanurate, urea and/or allophanate groups. Oligomerization can
be carried out readily with low molecular mass polyols such as
trimethylolpropane or homotrimethylolpropane, glycerol, and the
like. Dimers are known for instance from U.S. Pat. No.
2,671,082.
[0028] Preferred diisocyanate functional compounds include IPDI,
MDI, and blends, such as a mixture of isomers, e.g., 2,4-tolylene
diisocyanate and 2,6-tolylene diisocyanate. After formation of an
adduct of polyisocyanate and organosilane, free isocyanate groups
preferably remain, but in alternative embodiments, free NCO may
optionally be partially or completely blocked using conventional
blocking agents, or adjacent groups internally blocked by formation
of uretdione structures, for example. Examples of known blocking
agents are derived from any suitable aliphatic, cycloaliphatic,
aromatic, or alkylaromatic monoalcohol, monoamide, monoamine, or
monooxime. Ketoximes are well-known and unblock at relatively low
temperatures such as 120.degree. C. More sterically hindered,
acid-stable blocking groups include lactams of aminoacids, such as
the lactam of 6-aminohexanoic acid and/or benzotriazole. Other
blocking groups include the active methylene compounds such as
ethyl sec-butyl malonate, acetoacetates, e.g., C.sub.1-C.sub.8
alkyl acetoacetates, for example, n-butyl acetoacetate, isobutyl
acetoacetate, sec-butyl acetoacetate, and t-butyl acetoacetate; and
betadiketones such as acetylacetone.
[0029] In an alternative to an isocyanatosilane adduct (A) as
silane component in the adhesive is an isocyanotosilane such as are
made by pyrolysis of carbamate (silylorganohalide and metal
cyanate) or reacting silicon hydride and allyl isocyanate.
Isocyanatosilanes containing at least one, or more than one
hydrolyzable group and one free isocyanate group are known in the
art and typically represented by the structure ##STR5## wherein
R.sup.1 is a monovalent aliphatic, cycloaliphatic or aromatic
radical having from 1 to 20 carbon atoms, and is preferably
selected from the group consisting of alkyl radicals having from 1
to 4 carbon atoms, cycloalkyl radicals having from 4 to 7 ring
carbon atoms, aryl radicals having 6, 10, or 14 nuclear carbon
atoms, and such aryl radicals containing one or more substituent
alkyl groups having from 1 to 4 carbon atoms; R.sup.2 is a
monovalent aliphatic, cycloaliphatic or aromatic organic radical
containing from 1 to 8 carbon atoms and is preferably selected from
the group consisting of alkyl radicals having from 1 to 4 carbon
atoms, --R.sup.3--O--R.sup.4, and ##STR6## where R.sup.3 is an
alkylene group having from 1 to 4 carbon atoms and R.sup.4 is an
alkyl group having from 1 to 4 carbon atoms; a is zero or 1, and
preferably is zero; and Z is a divalent organic radical attached to
the silicon atom via a carbon-silicon bond. The exact nature of the
Z radical is not critical, i.e., the radical can have any
configuration and combination of groupings that are compatible with
the isocyanato groups. For example, the Z radical can be a
hydrocarbon radical, or it can contain linkages such as ether,
ureido, urethane, and thiourethane linkages. The Z radical can
contain substitutent groups such as halogen. The isocyanatosilane
preferably contains an average of at least one hydrolyzable silane
group, and preferably two such groups in addition to at least one
free isocyanate group per molecule. Useful ranges of molecular
weight are from 200 to about 2,000. An example of an
isocyanatosilane useful in the present invention is Silquest.TM.
A-1310, which is gamma-isocyanatopropyltriethoxysilane.
[0030] The adhesive can optionally further contain known and
customary adjuvants including acid scavengers such as zinc oxide,
magnesium oxide; lead salts such as dibasic lead phosphite, dibasic
lead phthalate, monohydrous tribasic lead maleate, tetrabasic lead
fumarate, and mixtures thereof; epoxy compounds or resins, such as
glycidyl ethers of bisphenol A, epoxysilanes, and epoxyphenolics;
fillers such as precipitated silica, TiO.sub.2; reinforcing agents
such as carbon black; and tinting or coloring agents such as color
pigments and dyes.
[0031] The adhesive according to the invention is versatile and
bonds a variety of elastomers and low-polarity polymeric substrates
to structural parts, such as metallic window channels, trim strips,
bumper guards, edge moldings and the like. The polymeric materials
as well as the substrates are not limited as to the variety of
compositions and shapes. Shaped articles include foils, extrusion
profiles, coils, injection molded parts that are bondable. Bonding
of the polymer material can be to a similar or different material.
A rigid thermoplastic can be bonded to an elastomeric material. An
elastomer can be bonded to a dissimilar substrate such as wood,
metal, or glass. Representative metals are selected from any of the
common structural metals such as iron, steel (including stainless
steel), lead, aluminum, copper, brass, bronze, MONEL.RTM., nickel,
zinc, and treated metals with phosphatizing, galvanizing, and the
like. Prior to bonding, a metal surface is typically cleaned
according to one or more methods known in the art such as
degreasing, grit-blasting and zinc-phosphatizing. The non-metallic
substrates include glass panels, woven or nonwoven glass fabrics,
continuous rovings of glass, such as E-glass; fabrics, fibers or
rovings of polyamides, polyester, and aramids, e.g., Kevlar, a
trademark of E. I. du Pont de Nemours Co., (Inc.),
[0032] Aluminum and steel profiles are especially bondable to TPE
with the adhesive, in the absence of a nitroso compound. The
bondable polymeric substrate materials include the low surface
energy (<45 dynes/cm) polyolefins (e.g. polypropylene,
polyethylene, polyethylene-co-propylene, copolymers of
C.sub.4-C.sub.8 .alpha.-olefins with ethylene and/or propylene,
polyethylene foams, polypropylene foams, ethylene-propylene-diene
terpolymer (EPDM) rubbers, ethylene-propylene rubbers (EPR), etc.),
styrene-ethylene-butene-styrene copolymer (SEBS),
styrene-ethylene-propylene-styrene copolymer (SEPS),
styrene-isoprene-styrene (SIS) rubbers, styrene-butadiene-styrene
(SBS) rubbers, to name a few of these.
[0033] The adhesive compositions are applied to the substrate
surface in a conventional manner such as by dipping, spraying,
brushing, and the like. The substrate surface is dried before
contacting to the polymer to be bonded. In one bonding method, the
surface has been treated with the adhesive and the polymer pressed
together with the adhesive layer in between, and the assembly is
heated to the desired temperature tolerated by the polymer. The
conditions are preselected upon considering the particular polymer
or elastomer being bonded and whether or not it is cured after
contact or cured prior to contact with the substrate. If the
polymer is a curable type and is uncured, the curing is to be
effected during bonding, the conditions will be dictated by the
polymer composition. Vulcanizable elastomers will generally be
cured at a temperature of from about 140.degree. C. to about
200.degree. C. for a time ranging from about 5 to about 60 minutes.
If the polymer of the curable type has been cured, the bonding
temperature may range from about 90.degree. C. to above 180.degree.
C. for from 15 to about 120 minutes. Alternatively, in situations
where applicable, the adhesives can be interspersed between the
surfaces to be joined as a solid film or tape (100% solids adhesive
system) with bonding being accomplished as before.
Extrusion Bonding
[0034] A preferred method aspect according to the invention
includes the bonding of thermoplastic processed polymer to a
continuous or elongated structural member which has been
pre-treated with the adhesive. The treated member is passed
adjacent to or through an extruder die, and joined to the molten
polymer extrudate, followed by cooling of the joined article. The
treated substrate may be preheated off-line, and may be brought to
a desired temperature state at the time of joining with the
extrudate. This can be effected by feeding an elongated structural
profile, such as a metal strip, a shaped profile such as a channel
into an extruder die adapted to receive the elongated member.
Durable adhesion between the adhesive treated portion of the
profile substrate and the extruded polymer is achieved with or
without a previous heat treatment on the adhesive pre-treated
substrate prior to joining in this known manner.
[0035] In another method aspect, a structural article is inserted
by the piece into the cavity of an injection mold, melt processible
polymer is injected into the closed mold cavity thereby contacting
the pretreated surface of the inserted article, causing a bonding
between the polymer and substrate. The adhesive is especially
adapted for bonding thermoplastic injected polymer within the mold
cavity in this known manner. This method comprises treating a
predetermined side, or section of a side of a rigid substrate,
e.g., stamped or shaped metal with the adhesive herein, and drying.
The treated substrate is inserted into the cavity of the injection
mold at a predetermined location, and the mold is closed. Molten
thermoplastic is injected into the mold contacting the adhesive
treated portion of the substrate. After cooling sufficient for
ejecting the bonded article, the finished molding is ejected or
removed from the parted mold. Durable adhesion between the adhesive
treated portion of the inserted rigid substrate and the melt
process polymer is achieved with or without a previous heat
treatment on the adhesive-coated substrate prior to joining to the
thermoplastic melt.
EXAMPLE 1
[0036] Adhesive examples A-I, were prepared by mixing.
TABLE-US-00001 % DRY WEIGHTS RAW MATERIALS A B C D E F G H I
Chlorinated polypropylene (A) 95.0 87.0 80.0 89.0 80.0 67.0 80.0
67.0 57.0 MDI - Polydiphenylmethane- 11.0 20.0 33.0 diisocyanate
(B) Adduct of (B) with .gamma.- 20.0 33.0 43.0 aminopropyl
triethoxysilane (80:20 by wt.) amino alkyl trimethoxysilane (C) 5.0
13.0 20.0 Total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0
100.0
[0037] Adhesives above were prepared in xylene at solids ranges
between 21-35%.
[0038] The above adhesives were applied to aluminum coil panels at
a DFT of from 0.0003 to 0.0004 inch (0.007-0.010 mm). Adhesive was
applied to the aluminum panels using a #40 draw down bar. Polymer
materials injection molded to the adhesive treated panels which
were inserted into the mold cavity were Santoprene.RTM. and
Sarlink.RTM. TPE. Santoprene.RTM. is supplied by Advanced Elastomer
Systems. Sarlink.RTM. supplied by DSM Elastomers. After the
adhesive was applied to the metal panels, solvent was driven off by
heating allowing a peak metal temperature of 435.degree. F.
(223.degree. C.) in an oven set at 485.degree. F. (251.degree.
C.).
[0039] Samples where indicated were preheated prior to injection
molding bonding for 2'@250.degree. F. (121.degree. C.). In either
instance, with or without a preheat, excellent bonds were obtained
in accordance with the invention. Insert molding bonding was
obtained using a Toyo.RTM. injection molding press under the
following conditions:
[0040] Injection Pressure 1,100 psi (7,000 kPa), mold temperature:
160.degree. F. (71.degree. C.) Cooling cycle: 45 sec.; zone
temperatures: 1-450.degree. F. (232.degree. C.), 2-450.degree. F.
(232.degree. C.), 3-440.degree. F. (226.degree. C.), 4-430.degree.
F. (221.degree. C.), and 5-420.degree. F. (215.degree. C.)
[0041] Adhesion testing was completed using pliers to peel the
polymer from the metal substrate by hand. In the T-peel testing the
aluminum panels bent often the adhesive was released from the
metal. The percent rubber represents the amount of rubber adhering
to the metal substrate after peeling as a percent of the bond area.
TABLE-US-00002 Santoprene .RTM. Sarlink .RTM. 0' 2' 0' 2' On
aluminum PREHEAT PREHEAT PREHEAT PREHEAT ADHESIVE A 8% 8% 30% 45%
ADHESIVE B 0% 0% 0% 0% ADHESIVE C 0% 0% 0% 0% ADHESIVE D 10% 5% 98%
60% ADHESIVE E 5% 2% 38% 0% ADHESIVE F 0% 0% 70% 0% ADHESIVE G 50%
85% 85% 73% ADHESIVE H 50% 55% 73% 85% ADHESIVE I 45% 80% 43%
97%
[0042] The combination of chlorinated polypropylene and
silane-isocyanate adduct bonds a both types of TPE as indicated by
the minimum 50% polymer retention by the hand-peel test, as
compared to adhesives A-F containing either component alone.
Improvement in bonding with and without a preheating step. Most of
the failure mode was the result of the metal being bent during
testing.
[0043] The above examples G, H and I were repeated using stainless
steel as the substrate. TABLE-US-00003 Stainless steel Santoprene
.RTM. Sarlink .RTM. 0' 2' 0' 2' PREHEAT PREHEAT PREHEAT PREHEAT
ADHESIVE G 83% 98% 93% 75% ADHESIVE H 73% 97% 63% 93% ADHESIVE I
55% 55% 88% 89%
EXAMPLE 2
[0044] The following adhesives were applied at 0.0003-0.0004 inch
(0.007-0.010 mm) to aluminum coil panels to compare different film
forming polymers. The peak metal temperature after drying the
adhesive was 435.degree. F. (224.degree. C.) in an oven set at
500.degree. F. (260.degree. C.). Each TPE was dried overnite at
160.degree. F. (71.degree. C.) before molding. TABLE-US-00004
Adhesive in Xylene Raw Materials % TSC 45A 45B 45C 45D 45E
Chlorinated polypropylene 15 70 0 0 0 0 Chlorosulfonated PE-1* 10 0
70 0 0 0 Chlorosulfonated PE-2* 20 0 0 70 0 0 Chlorinated NR* 30 0
0 0 70 0 Modified polyolefin 25 0 0 0 0 70 (Eastman 440-1) Silane
adduct (Ex. 1) 19.75 30 30 30 30 30 % Total 16.00 16.00 16.00 16.00
16.00 solids Dry Wt % 100 100 100 100 100 Mixing: Add adhesive and
roll for 1 hour. *as taught in U.S. Pat. No. 4,031,120 absent
nitroso cpd.
[0045] Insert molding bonded composites were obtained using a
Toyo.RTM. injection molding press under the following
conditions:
[0046] Injection Pressure 1,100 psi (7,000 kP), mold temperature:
160.degree. F. (71.degree. C.) Cooling cycle: 45 sec.; zone
temperatures: 1-450.degree. F. (232.degree. C.), 2-450.degree. F.
(232.degree. C.), 3-440.degree. F. (226.degree. C.), 4-430.degree.
F. (221.degree. C.), and 5-420.degree. F. (215.degree. C.)
[0047] Failure modes are: R-polymer; RC-polymer-to-adhesive;
CM-adhesive-to-metal TABLE-US-00005 Testing: Primary Adhesion
Adhesive R TR RC CM CP to Elastomer: Santoprene .RTM. - 2''/min
peel rate 45A 99 1 95 5 97 -- 3 -- -- 45B 100 100 -- -- 100 -- --
45C 100 100 -- -- 100 -- -- 45D 100 100 -- -- 100 -- -- 45E 100 100
-- -- 100 -- -- to Elastomer: Sarlink .RTM. - 2''/min peel rate 45A
90 10 100 95 -- 10 -- -- 45B 100 100 -- -- 100 -- -- 45C 100 100 --
-- 100 -- -- 45D 100 100 100 45E 100 100 -- -- 100 -- --
[0048] The peel results illustrate that Example 2-A bonds metal
well to both TPE polymers whereas example 2B-2F fails in adhesive
to polymer mode.
EXAMPLE 3
[0049] The adhesive formulations of Example 2 were tested in
bonding other polymers such as elastomers under compression molding
during vulcanization without a prebake. The adhesives were spray
applied on pre-heated (150.degree. F./65.degree. C.) zinc
phosphatized steel panels. Dry film thickness was 0.001 inch (0.025
mm). The treated panels were each inserted in a compression mold
and raw elastomer stock applied. The Elastomers were cured as
follows:
[0050] Natural rubber 1-13'@340.degree. F. (171.degree. C.)
[0051] Natural rubber 2-13.5'@340.degree. F. (171.degree. C.)
[0052] Nitrile rubber 1-19.5'@340.degree. F. (171.degree. C.)
[0053] SBR 1-18'@340.degree. F. (171.degree. C.)
[0054] Peroxide cured EPDM-7.5'@340.degree. F. (171.degree. C.)
[0055] Peroxide cured silicone-5'@350.degree. F. (176.degree.
C.)
[0056] "*" denotes sweep, a loss of bonding due to movement of
adhesive by the injection melt flow in the mold.
[0057] Failure modes are: R-rubber; RC-rubber-to-cement;
CM-cement-to-metal. HP--denotes hand peeled. Where indicated,
primary adhesion peel strength values in N/m were obtained per ASTM
D429B. Percent of failure mode is of the bond area. TABLE-US-00006
% % % Ex. N/m R RC CM Nat. Rubber 1 45A HP 20 80 HP 40 60 -- -- 30
70 45B HP 20 80 HP 40 60 -- -- 30 70 45C HP 90 10 HP 10 90 -- -- 50
50 45D HP 100 HP 100 -- -- 100 -- 45E HP 50 50 HP 30 70 -- -- 40 60
Nat. Rubber 2 45A HP 100 875 75 25 875 -- 75 63 45B HP 100 HP 90 10
-- -- 95 10 45C HP 100 HP 10 90 -- -- 10 95 45D HP 100 HP 100 -- --
100 -- 45E HP 50 50 HP 100 -- -- 50 75 Nitrile Rubber 1 45A 7700 5
95 1068 30 70 9280 18 -- 83 45B 11031 5 10 85 11381 10 10 80 11206
8 10 83 45C HP 100 HP 100 -- -- -- 100 45D 16460 100 18210 100
17334 100 -- -- 45E HP 100 HP 100 -- -- 100 100 SBR 1 45A 13132 10
70 20 7879 80 20 10506 10 75 20 45B 9105 5 20 75 8579 20 80 8930 5
20 78 45C HP 5 95 6303 10 90 6303 -- 8 93 45D HP 100 HP 100 -- --
100 -- 45E HP 100 HP 50 50 -- -- 75 50 EPDM 45A 6828 95 5 8755 85
10 5 7879 90 8 5 45B 6128 30 70 5077 10 90 5603 20 -- 80 45C 2626 5
95 2276 5 95 2451 -- 5 95 45D 4902 95 5 5253 60 40 5077 78 23 --
45E* 3151 5 95 3677 5 65 30 3502 5 65 63 Silicone 45A 100 100 -- --
100 -- 45B 100 100 -- -- 100 -- 45C 100 100 -- -- 100 -- 45D 100
100 -- -- 100 -- 45E* 80 20 70 30 -- -- 75 25
* * * * *