U.S. patent application number 15/582803 was filed with the patent office on 2017-08-17 for cyanoacrylate compositions.
The applicant listed for this patent is Henkel IP & Holding GmbH. Invention is credited to Barry N. Burns, Comac Duffy, Clara Goff, John Guthrie, John Killoran, Marisa Phelan, Bernard Ryan.
Application Number | 20170233618 15/582803 |
Document ID | / |
Family ID | 58708088 |
Filed Date | 2017-08-17 |
United States Patent
Application |
20170233618 |
Kind Code |
A1 |
Phelan; Marisa ; et
al. |
August 17, 2017 |
CYANOACRYLATE COMPOSITIONS
Abstract
This invention relates to cyanoacrylate-containing compositions,
which when cured provide improved heat resistance.
Inventors: |
Phelan; Marisa; (Co.
Tipperary, IE) ; Duffy; Comac; (Co. Louth, IE)
; Killoran; John; (Dublin, IE) ; Burns; Barry
N.; (Dublin, IE) ; Guthrie; John; (Prosperous
Naas, IE) ; Ryan; Bernard; (Scholarstown, IE)
; Goff; Clara; (Dublin, IE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Henkel IP & Holding GmbH |
Duesseldorf |
|
DE |
|
|
Family ID: |
58708088 |
Appl. No.: |
15/582803 |
Filed: |
May 1, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13226184 |
Sep 6, 2011 |
9657120 |
|
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15582803 |
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Current U.S.
Class: |
156/330.9 |
Current CPC
Class: |
C08F 22/32 20130101;
C09J 5/00 20130101; C09J 11/06 20130101; C08F 222/34 20130101; C09J
5/06 20130101; C08F 222/32 20130101; C08F 222/32 20130101; C09J
4/00 20130101; C08F 222/32 20130101; C08F 222/322 20200201; C08F
222/322 20200201; C08F 20/34 20130101; C09J 133/14 20130101; C09J
2433/00 20130101; C09J 4/00 20130101; C08F 20/00 20130101; C08F
120/34 20130101; C08F 222/32 20130101 |
International
Class: |
C09J 133/14 20060101
C09J133/14; C09J 5/00 20060101 C09J005/00 |
Claims
1. A cyanoacrylate adhesive composition having improved resistance
to thermal degradation at elevated temperature conditions of at
least 120.degree. C., comprising: (a) ally-2-cyanoacrylate, and (b)
a bis-functional cyanoacrylate in an amount of about 10 to about 20
weight percent based on the cyanoacrylate adhesive composition.
2. (canceled)
3. The composition according to claim 1, further comprising a
member selected from the group consisting of methyl cyanoacrylate,
ethyl-2-cyanoacrylate, propyl cyanoacrylates, butyl cyanoacrylates,
octyl cyanoacrylates, and .beta.-methoxyethyl cyanoacrylate.
4-5. (canceled)
6. The composition according to claim 1, wherein the
bis-cyanoacrylate is selected from the group consisting of
1,10-decanediol bis-cyanoacrylate, 1,8-octanediol
bis-cyanoacrylate, and 1,6-hexanediol bis-cyanoacrylate.
7. The composition of claim 1, further comprising a stabilizing
amount of an acidic stabilizer and a free radical inhibitor.
8. The composition according to claim 1, further comprising an
accelerator component.
9. The composition according to claim 8, wherein the accelerator
component is selected from the group consisting of calixarene,
oxacalixarene, silacrown, cyclodextrin, crown ether,
poly(ethyleneglycol) di(meth)acrylate, ethoxylated hydric compound,
and combinations thereof.
10. The composition according to claim 9, wherein the crown ether
is selected from members within the group consisting of 15-crown-5,
18-crown-6, dibenzo-18-crown-6,
benzo-15-crown-5-dibenzo-24-crown-8, dibenzo-30-crown-10,
tribenzo-18-crown-6, asym-dibenzo-22-crown-6, dibenzo-14-crown-4,
dicyclohexyl-18-crown-6, dicyclohexyl-24-crown-8,
cyclohexyl-12-crown-4, 1,2-decalyl-15-crown-5,
1,2-naphtho-15-crown-5, 3,4,5-naphtyl-16-crown-5,
1,2-methyl-benzo-18-crown-6, 1,2-methylbenzo-5,
6-methylbenzo-18-crown-6, 1,2-t-butyl-18-crown-6,
1,2-vinylbenzo-15-crown-5, 1,2-vinylbenzo-18-crown-6,
1,2-t-butyl-cyclohexyl-8-crown-6, asym-dibenzo-22-crown-6, and
1,2-benzo-1,4-benzo-5-oxygen-20-crown-7 and combinations
thereof.
11. The composition according to claim 1, further comprising
additives selected from the group consisting of tougheners, shock
resistant additives, thixotropy conferring agents, thickeners,
dyes, and combinations thereof.
12. Reaction products of the composition according to claim 1.
13. A method of bonding together two substrates, comprising the
steps of: applying a cyanoacrylate-containing composition according
to claim 1, to at least one of the substrates and mating together
the substrates for a time sufficient to permit the adhesive to
fixture.
14. A method of preparing a cyanoacrylate-containing composition
according to claim 1, comprising the steps of: providing an
allyl-2-cyanoacrylate, and combining therewith with mixing a
bis-cyanoacrylate component.
15. (canceled)
Description
BACKGROUND
Field
[0001] This invention relates to cyanoacrylate-containing
compositions, which when cured provide improved heat
resistance.
Brief Description of Related Technology
[0002] Cyanoacrylate adhesive compositions are well known, and
widely used as quick setting, instant adhesives with a wide variety
of uses. See H. V. Coover, D. W. Dreifus and J. T. O'Connor,
"Cyanoacrylate Adhesives" in Handbook of Adhesives, 27, 463-77, I.
Skeist, ed., Van Nostrand Reinhold, New York, 3rd ed. (1990). See
also G. H. Millet, "Cyanoacrylate Adhesives" in Structural
Adhesives: Chemistry and Technology, S. R. Hartshorn, ed., Plenun
Press, New York, p. 249-307 (1986).
[0003] In the past, efforts have been made to improve the heat
resistance of cured products of cyanoacrylate composition,
particularly upon exposure to temperatures of 80.degree. C. and
greater. As the cured products are thermoplastic in nature they
tend to soften as the temperature increases and when the T.sub.g of
the material is surpassed the cured product begins to flow. As the
temperature increase progresses, a degradation begins and the
physical properties deteriorate. As a result, commercial
applications for cyanoacrylates where exposure to elevated
temperature conditions is likely have proven tricky and
consequently have been limited.
[0004] Attempts to remedy this situation have been undertaken in
the past.
[0005] For instance, U.S. Pat. No. 5,288,794 (Attarwala) is
directed to an improved cyanoacrylate monomer adhesive formulation,
where an effective amount, for enhancing the thermal resistance of
the polymerized adhesive, of a mono, poly or hetero aromatic
compound characterized by at least three substitutions on an
aromatic ring thereof, two or more of the substitutions being
electron withdrawing groups, is provided. Examples of the aromatic
compound are given as 2,4-dinitrofluorobenzene;
2,4-dinitrochlorobenzene; 2,4-difluoronitrobenzene;
3,5-dinitrobenzonitrile; 2-chloro-3,5-dinitrobenzonitrile;
4,4'-difluoro-3,3'-dinitrophenyl sulfone; pentafluoronitrobenzone;
pentafluorobenzonitrile;
.alpha.,.alpha.,.alpha.-2-tetrafluoro-p-tolunitrile and
tetrachloroterphthalonitrile.
[0006] Prior to the discovery in the '794 patent, numerous attempts
have been made to improve the thermal stability of cyanoacrylate
adhesive bonds.
[0007] For instance, U.S. Pat. No. 3,832,334 is directed to the
addition of maleic anhydride, which is reported to produce
cyanoacrylate adhesives having increased thermal resistance (when
cured) while preserving fast cure speed.
[0008] U.S. Pat. No. 4,196,271 is directed to tri-, tetra- and
higher carboxylic acids or their anhydrides, which are reported to
be useful for improving heat resistance of cured cyanoacrylate
adhesives.
[0009] U.S. Pat. No. 4,450,265 is directed to the use of phthalic
anhydride to improve heat resistance of cyanoacrylate adhesives.
More specifically, the '265 patent is directed to and claims an
adhesive composition comprising a polymerizable constituent the
major part of which comprises at least one ester of 2-cyanoacrylic
acid, characterized in that the composition additionally comprises
a proportion of phthalic anhydride effective for favorably
influencing the strength and/or durability of adhesive bonds formed
from the composition, under exposure to moisture or elevated
temperature. The effective amount is reported as 0.1% to 5.0%, such
as 0.3% to 0.7%, by weight of the composition. The '265 patent
reports the superiority of phthalic anhydride over compositions
where no additive was used, and where maleic anhydride was used
(though less pronounced in the case of stainless steel lap shears
than in those of aluminium).
[0010] U.S. Pat. No. 4,532,293 is directed to the use of
benzophenonetetracarboxylic acid or its anhydride to provide a
superior heat resistance for cyanoacrylate adhesives.
[0011] U.S. Pat. No. 4,490,515 is directed to cyanoacrylate
compositions containing certain maleimide or nadimide compounds to
improve hot strength properties.
[0012] U.S. Pat. No. 4,560,723 describes certain cyanoacrylate
adhesives containing a certain treated copolymer toughener, and a
"sustainer" compound having certain compatibility properties said
to provide improved retention of toughness on heat aging of the
cured adhesive. Various substituted aryl compounds are identified
as suitable "sustainers," including nitrobenzene,
1,2-dichlorobenzene, 1,2,4-trichlorobenzene and
bromochlorobenzene.
[0013] One way to improve thermal stability without resorting to
additive chemistry involves the use of an allyl-2-cyanoacrylate, in
whole or in part, as the cyanoacrylate component. It is believed
that allyl-2-cyanoacrylate will undergo a cross-linking reaction
through the allyl functional groups, once given a post-bake (either
as an additional process step or as a result of the environment in
which they are used) after the initial cure occurs.
[0014] While the application of a post-bake certainly provides an
allyl-2-cyanoacrylate-containing adhesive with significant
improvements in thermal durability (see FIG. 1), post-bake
processing is not devoid of its own issues. For instance, the
additional step of a post-bake requires added labor, time and
expense to the process. And, a post-bake results in a considerable
loss in initial performance while the cross-links are being formed
thermally. This loss is referred to as "the dip", with bond
strength recovery occurring after approximately one week at a
temperature of 150.degree. C. (See FIG. 1.)
[0015] Despite these efforts, there has been a long standing, but
unmet, desire to achieve more robust thermal performance from
cyanoacrylate compositions. It would accordingly be quite
advantageous to provide a solution to that desire.
SUMMARY
[0016] The present invention remedies the shortcomings on thermal
performance of cyanoacrylate compositions by providing a
cyanoacrylate composition, which when cured provides improved heat
resistance, through broadly speaking the combination of (a) a
mono-functional cyanoacrylate component and (b) a multi-functional
cyanoacrylate component.
[0017] This invention is also directed to a method of bonding
together two substrates, which method includes applying to at least
one of the substrates a composition as described above, and
thereafter mating together the substrates.
[0018] In addition, the present invention is directed to reaction
products of the inventive compositions.
[0019] Also, the invention is directed to a method of preparing the
inventive compositions.
[0020] The invention will be more fully understood by a reading of
the section entitled "Detailed Description of the Invention", which
follows.
BRIEF DESCRIPTION OF THE FIGURES
[0021] FIG. 1 shows an X--Y plot of thermal performance of
allyl-2-cyanoacrylate on grit blasted mild steel, after aging at a
temperature of 150.degree. C. On the plot, X is time (days) and Y
is bond strength [N/mm.sup.2].
[0022] FIGS. 2A and 2B show in a bar chart format hot strength (at
a temperature of 120.degree. C. and 150.degree. C.), respectively,
of LOCTITE 401, ethyl-2-cyanoacrylate, allyl-2-cyanoacrylate and
ethyl-2-cyanoacrylate containing 10 and 15 wt % of 1,8-octanediol
bis-cyanoacrylate where the three time elements are given in the
legend. FIG. 2C shows an X--Y plot of thermal durability (at a
temperature of 150.degree. C.) of ethyl-2-cyanoacrylate
(represented by the open circle), and ethyl-2-cyanoacrylate
containing 10 (represented by the open triangle) and 15 wt % of
1,8-octanediol bis-cyanoacrylate (represented by the open diamond).
On the plot, Y is bond strength [N/mm.sup.2].
[0023] FIGS. 3-6 show X--Y plots of bond strength retention over
time (in days) at successively greater elevated temperatures
(120.degree. C., 150.degree. C., 180.degree. C., and 200.degree.
C., respectively) of formulations prepared from a mono-functional
cyanoacrylate (allyl-2-cyanoacrylate) and a multi-functional
cyanoacrylate (1,6-hexanediol bis-cyanoacrylate, at progressively
greater levels with the open diamond representing 5%, the open
triangle representing 10% and the open square representing 15%)
compared with a control (without the bis-cyanoacrylate, represented
by the open circle) on grit blasted mild steel substrates. On the
plots, Y is bond strength [N/mm.sup.2].
[0024] FIGS. 7-10 show X--Y plots of bond strength retention over
time (in days) at successively greater elevated temperatures
(120.degree. C., 150.degree. C., 180.degree. C., and 200.degree.
C., respectively) of rubber toughened formulations prepared from
allyl-2-cyanoacrylate/ethyl-2-cyanoacrylate as the mono-functional
cyanoacrylate and a multi-functional cyanoacrylate (1,6-hexanediol
bis-cyanoacrylate, at progressively greater levels with the open
diamond representing 5%, the open triangle representing 10%, the
open square representing 12.5%, and the X representing 15%)
compared with a control (without the bis-cyanoacrylate, represented
by the open circle) on grit blasted mild steel substrates. On the
plots, Y is bond strength [N/mm.sup.2].
[0025] FIG. 11 shows in a bar chart format bonding performance in
terms of tensile strength after a room temperature cure of 24 hours
to various plastic substrates, for Samples E-I. The Y axis is
measured in N/mm.sup.2.
[0026] FIG. 12 show an X--Y plot of bond strength retention over
time (in days) at an elevated temperature of 150.degree. C. of
formulations prepared from a mono-functional cyanoacrylate
(allyl-2-cyanoacrylate) and a multi-functional cyanoacrylate
(1,6-hexanediol bis-cyanoacrylate, at progressively greater levels
with the open diamond representing 10%, the open triangle
representing 15% and the open square representing 20%) compared
with a control (without the bis-cyanoacrylate, represented by the
open circle) on grit blasted mild steel substrates. On the plot, Y
is bond strength [N/mm.sup.2].
[0027] FIG. 13 shows in a bar chart format bonding performance in
terms of tensile strength after a room temperature cure of 24 hours
to various plastic substrates, for Samples J-M. The Y axis is
measured in N/mm.sup.2.
DETAILED DESCRIPTION
[0028] As noted above, this invention is directed to a
cyanoacrylate composition, which when cured provides improved heat
resistance.
[0029] The cyanoacrylate component includes at least one
mono-functional cyanoacrylate monomer which may be chosen with a
raft of substituents, such as those represented by
H.sub.2C.dbd.C(CN)--COOR, where R is selected from C.sub.1-15
alkyl, alkoxyalkyl, cycloalkyl, alkenyl, aralkyl, aryl, allyl and
haloalkyl groups. Desirably, the cyanoacrylate monomer is selected
from at least one, desirably at least two, of methyl cyanoacrylate,
ethyl-2-cyanoacrylate, propyl cyanoacrylates, butyl cyanoacrylates
(such as n-butyl-2-cyanoacrylate), octyl cyanoacrylates,
allyl-2-cyanoacrylate, .beta.-methoxyethyl cyanoacrylate and
combinations thereof. A particularly desirable mono-functional
cyanoacrylate monomer includes allyl-2-cyanoacrylate. A
particularly desirable combination of mono-functional cyanoacrylate
monomers includes allyl-2-cyanoacrylate together with an alkyl
cyanoacrylate, such as ethyl-2-cyanoacrylate.
[0030] The mono-functional cyanoacrylate component should be
included in the compositions in an amount within the range of from
about 50% to about 99.98% by weight, with the range of about 70% to
about 85% by weight, of the total composition being desirable.
[0031] In addition to the mono-functional cyanoacrylate component
is a multi-functional cyanoacrylate component. Multi-functional
cyanoacrylate components are ordinarily bis-cyanoacrylates, but may
be tri-functional, tetra-functional or penta-functional as
well.
[0032] Bis-cyanoacrylates are embraced by structure I
##STR00001##
where R in structure I is a linkage selected from (CH.sub.2).sub.n,
with n being 2, 3, 4, 5, 6, 8, 9, 10, or 12, such as a linear or
branched chain alkylene. Bis-cyanoacrylates of this sort may be
prepared through a transesterification reaction using an
appropriate diol to yield the alkylene center segment for "R".
Desirable examples of these bis-cyanoacrylates include
1,10-decanediol bis-cyanoacrylate, 1,8-octanediol
bis-cyanoacrylate, and 1,6-hexane bis-cyanoacrylate. An appropriate
synthetic method to yield such bis-cyanoacrylates may be found
generally in U.S. Pat. No. 3,975,422 (Buck), U.S. Pat. No.
4,012,402 (Buck), and U.S. Pat. No. 6,096,848 (Gololobov), and
International Patent Publication No. WO 2010/091975.
[0033] The multi-functional cyanoacrylate component should be
included in the compositions in an amount within the range of from
about 5% to about 30% by weight, with the range of about 10% to
about 20% by weight, of the total composition being desirable.
[0034] Accelerators may also be included in the inventive
cyanoacrylate compositions, such as any one or more selected from
calixarenes and oxacalixarenes, silacrowns, crown ethers,
cyclodextrins, poly(ethyleneglycol) di(meth)acrylates, ethoxylated
hydric compounds and combinations thereof.
[0035] Of the calixarenes and oxacalixarenes, many are known and
are reported in the patent literature. See e.g. U.S. Pat. Nos.
4,556,700, 4,622,414, 4,636,539, 4,695,615, 4,718,966, and
4,855,461, the disclosures of each of which are hereby expressly
incorporated herein by reference.
[0036] For instance, as regards calixarenes, those within the
following structure are useful herein:
##STR00002##
where R.sup.1 is alkyl, alkoxy, substituted alkyl or substituted
alkoxy; R.sup.2 is H or alkyl; and n is 4, 6 or 8.
[0037] One particularly desirable calixarene is tetrabutyl
tetra[2-ethoxy-2-oxoethoxy]calix-4-arene.
[0038] A host of crown ethers are known. For instance, examples
which may be used herein either individually or in combination,
include 15-crown-5, 18-crown-6, dibenzo-18-crown-6,
benzo-15-crown-5-dibenzo-24-crown-8, dibenzo-30-crown-10,
tribenzo-18-crown-6, asym-dibenzo-22-crown-6, dibenzo-14-crown-4,
dicyclohexyl-18-crown-6, dicyclohexyl-24-crown-8,
cyclohexyl-12-crown-4, 1,2-decalyl-15-crown-5,
1,2-naphtho-15-crown-5, 3,4,5-naphtyl-16-crown-5,
1,2-methyl-benzo-18-crown-6, 1,2-methylbenzo-5,
6-methylbenzo-18-crown-6, 1,2-t-butyl-18-crown-6,
1,2-vinylbenzo-15-crown-5, 1,2-vinylbenzo-18-crown-6,
1,2-t-butyl-cyclohexyl-18-crown-6, asym-dibenzo-22-crown-6 and
1,2-benzo-1,4-benzo-5-oxygen-20-crown-7. See U.S. Pat. No.
4,837,260 (Sato), the disclosure of which is hereby expressly
incorporated herein by reference.
[0039] Of the silacrowns, again many are known, and are reported in
the literature.
[0040] Specific examples of silacrown compounds useful in the
inventive compositions include:
##STR00003##
dimethylsila-11-crown-4;
##STR00004##
dimethylsila-14-crown-5;
##STR00005##
and dimethylsila-17-crown-6. [0041] See e.g. U.S. Pat. No.
4,906,317 (Liu), the disclosure of which is hereby expressly
incorporated herein by reference.
[0042] Many cyclodextrins may be used in connection with the
present invention. For instance, those described and claimed in
U.S. Pat. No. 5,312,864 (Wenz), the disclosure of which is hereby
expressly incorporated herein by reference, as hydroxyl group
derivatives of an .alpha., .beta. or .gamma.-cyclodextrin would be
appropriate choices as an accelerator component.
[0043] For instance, poly(ethylene glycol) di(meth)acrylates
suitable for use herein include those within the following
structure:
##STR00006##
where n is greater than 3, such as within the range of 3 to 12,
with n being 9 as particularly desirable. More specific examples
include PEG 200 DMA, (where n is about 4) PEG 400 DMA (where n is
about 9), PEG 600 DMA (where n is about 14), and PEG 800 DMA (where
n is about 19), where the number (e.g., 400) represents the average
molecular weight of the glycol portion of the molecule, excluding
the two methacrylate groups, expressed as grams/mole (i.e., 400
g/mol). A particularly desirable PEG DMA is PEG 400 DMA.
[0044] And of the ethoxylated hydric compounds (or ethoxylated
fatty alcohols that may be employed), appropriate ones may be
chosen from those within the following structure:
##STR00007##
where C.sub.m can be a linear or branched alkyl or alkenyl chain, m
is an integer between 1 to 30, such as from 5 to 20, n is an
integer between 2 to 30, such as from 5 to 15, and R may be H or
alkyl, such as C.sub.1-6 alkyl.
[0045] When used, the accelerator embraced by the above structures
should be included in the compositions in an amount within the
range of from about 0.01% to about 10% by weight, with the range of
about 0.1 to about 0.5% by weight being desirable, and about 0.4%
by weight of the total composition being particularly
desirable.
[0046] A stabilizer package is also ordinarily found in
cyanoacrylate compositions. The stabilizer package may include one
or more free radical stabilizers and anionic stabilizers, each of
the identity and amount of which are well known to those of
ordinary skill in the art. See e.g. U.S. Pat. Nos. 5,530,037 and
6,607,632, the disclosures of each of which are incorporated herein
by reference.
[0047] Other additives may be included in the inventive
cyanoacrylate compositions, such as certain acidic materials (like
citric acid), thixotropy or gelling agents, thickeners, dyes, and
combinations thereof.
[0048] In another aspect of the invention, there is provided a
method of bonding together two substrates, which method includes
applying to at least one of the substrates a composition as
described above, and thereafter mating together the substrates for
a time sufficient to permit the adhesive to fixture. For many
applications, the substrate should become fixed by the inventive
compositions in less than about 150 seconds, and depending on the
substrate as little as about 30 seconds.
[0049] In yet another aspect of the invention, there are provided
cured products of the so-described compositions.
[0050] In still another aspect of the invention, there is provided
a method of preparing the so-described compositions. The method
includes providing a mono-functional cyanoacrylate component, and
combining therewith a multi-functional cyanoacrylate component.
[0051] The invention will be further illustrated by the examples
which follow.
EXAMPLES
Synthesis
[0052] Initially, a series of bis-cyanoacrylates are synthesized,
consistent with the procedure set forth on page 14 of International
Patent Publication No. WO 2010/091975. Those bis-cyanoacrylates
are: 1,6-hexanediol bis-cyanoacrylate, 1,8-octanediol
bis-cyanoacrylate and 1,10-decanediol bis-cyanoacrylate.
Formulations
[0053] Cyanoacrylate compositions are prepared from a
mono-functional cyanoacrylate component and a multi-functional
cyanoacrylate component. In one sample, the mono-functional
cyanoacrylate component is chosen to be allyl-2-cyanoacrylate and
the multi-functional cyanoacrylate component is chosen to be
1,6-hexanediol bis-cyanoacrylate, a synthesis for which is
described in the preceding paragraph.
[0054] In the table below, four samples (A-D) are prepared with the
identified constituents in the noted amounts. In the Examples,
"Mono CA" refers to mono-functional cyanoacrylate or a compound
bearing a single cyanoacrylate group and "Multi CA" refers to
multi-functional cyanoacrylate or a compound bearing more than one
cyanoacrylate functional group.
TABLE-US-00001 Constituents Sample/Amt. (wt %) Type Identity A B C
D Mono CA Allyl CA 99.9 94.9 89.9 84.9 Multi CA Hex Diol -- 5 10 15
Bis-CA Accelerator 18 Crown 6 0.1 0.1 0.1 0.1 Stabilizer BF.sub.3 5
ppm 5 ppm 5 ppm 5 ppm
[0055] Each of Samples A-D is applied to grit blasted mild steel
lap shears, and bonded assemblies prepared for thermal performance
evaluation. Initially, a set of lap shear assemblies are aged at an
elevated temperature of 120.degree. C. Then the exposure
temperatures are increased to 150.degree. C., 180.degree. C. and
200.degree. C. Reference to FIGS. 3-6 shows that the use of a
multi-functional cyanoacrylate, such as 1,6-hexanediol
bis-cyanoacrylate, aids in minimizing the dip in
allyl-2-cyanoacrylate compositions.
[0056] Next, the mono-functional cyanoacrylate component is chosen
to be the combination of allyl-2-cyanoacrylate and
ethyl-2-cyanoacrylate, and the multi-functional cyanoacrylate
component was chosen to be 1,6-hexanediol bis-cyanoacrylate.
TABLE-US-00002 Sample/Amt. Constituents (wt %) Type Identity E F G
H I Mono CA ECA 44.95 42.45 39.95 38.70 37.45 Allyl CA 44.95 42.45
39.95 38.70 37.45 Multi CA Hex Diol 0 5 10 12.5 15 Bis-CA
Accelerator 18 Crown 0.1 0.1 0.1 0.1 0.1 6 Stabilizer BF.sub.3 10
ppm 10 ppm 10 ppm 10 ppm 10 ppm Rubber VAMAC 10 10 10 10 10
Toughener VCS 5500
[0057] In the table above, five samples (E-I) are prepared, each
with a VAMAC-branded elastomer as a rubber toughener.
[0058] Each of Samples E-I is applied to grit blasted mild steel
lap shears, and bonded assemblies prepared for thermal performance
evaluation. Initially, a set of lap shear assemblies are aged at an
elevated temperature of 120.degree. C. Then the exposure
temperatures are increased to 150.degree. C., 180.degree. C. and
200.degree. C. Reference to FIGS. 7-10 shows that the use of a
multi-functional cyanoacrylate, such as 1,6-hexanediol
bis-cyanoacrylate, aids in minimizing the dip in
allyl-2-cyanoacrylate/ethyl-2-cyanoacrylate compositions, even when
toughened, particularly with extended heat ageing even at
temperatures of 200.degree. C.
[0059] In addition, other performance evaluations, such as bonding
to plastic substrates, were considered. As shown in the table below
and with reference to FIG. 11, when applied to substrates
constructed of polycarbonate ("PC"), polymethylmethacrylate
("PMMA") and acrylonitrile:butadiene:styrene ("ABS"), Samples E-I
show the following performance in terms of tensile strength
[N/mm.sup.2] after a room temperature cure of 24 hours:
TABLE-US-00003 Sample Substrate E F G H I Polycarbonate 3.91 3.09
1.72 4.27 3.69 Polymethylmethacrylate 5.02 3.41 4.15 7.54 3.69
Acrylonitrile:butadiene:styrene 7.52 7.98 8.61 8.00 8.63
[0060] In the table below, four samples (J-M) are prepared, each
with a PMMA elastomer as a thickener.
TABLE-US-00004 Constituents Sample/Amt. (wt %) Type Identity J K L
M Mono CA ECA 46.7 41.7 39.2 36.7 Allyl CA 46.7 41.7 39.2 36.7
Multi CA Hex Diol 0 10 15 20 Bis-CA Accelerator 18 Crown 6 0.1 0.1
0.1 0.1 Stabilizer BF.sub.3 7 ppm 7 ppm 7 ppm 7 ppm Thickener PMMA
6.5 6.5 6.5 6.5
[0061] Each of Samples J-M is applied to grit blasted mild steel
lap shears, and bonded assemblies prepared for thermal performance
evaluation. A set of lap shear assemblies are aged at an elevated
temperature of 150.degree. C. Reference to FIG. 12 shows that the
use of a multi-functional cyanoacrylate, such as 1,6-hexanediol
bis-cyanoacrylate, aids in minimizing the dip in
allyl-2-cyanoacrylate/ethyl-2-cyanoacrylate compositions, even when
thickened with a PMMA.
[0062] Next, the extent to which Samples J-M bonded together
plastic substrates is evaluated. As shown in the table below and
with reference to FIG. 13, when applied to substrates constructed
of PC, PMMA and ABS, Samples J-M show the following performance in
terms of tensile strength [N/mm.sup.2] after a room temperature
cure of 24 hours:
TABLE-US-00005 Sample Substrate J K L M Polycarbonate 7.05 6.43
4.60 4.31 Polymethylmethacrylate 6.36 4.68 4.17 3.32
Acrylonitrile:butadiene:styrene 8.60 8.65 9.11 8.05
* * * * *