U.S. patent application number 12/148572 was filed with the patent office on 2009-02-19 for dental adhesive.
Invention is credited to Joachim E. Klee, Uwe Lehman.
Application Number | 20090048367 12/148572 |
Document ID | / |
Family ID | 40363482 |
Filed Date | 2009-02-19 |
United States Patent
Application |
20090048367 |
Kind Code |
A1 |
Klee; Joachim E. ; et
al. |
February 19, 2009 |
Dental adhesive
Abstract
Non-aqueous dental adhesive comprising a mixture containing (i)
one or more polymerizable monomers optionally containing an acidic
group, (ii) a polymerization initiator, and (iii) a thermal
polymerization inhibitor of the following formula (I): ##STR00001##
wherein R'.sub.1 represents a hydrogen atom, or a saturated
hydrocarbon group having 1 to 18 carbon atoms. R'.sub.2, which may
be the same or different if more than one R'.sub.2 is present,
independently represent a saturated hydrocarbon group having 1 to
18 carbon atoms, and c represents an integer of from 1 to 4, and
(iv) optionally an organic solvent.
Inventors: |
Klee; Joachim E.;
(Radolfzell, DE) ; Lehman; Uwe; (Konstanz,
DE) |
Correspondence
Address: |
DENTSPLY INTERNATIONAL INC
570 WEST COLLEGE AVENUE
YORK
PA
17404
US
|
Family ID: |
40363482 |
Appl. No.: |
12/148572 |
Filed: |
April 21, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10493721 |
Apr 26, 2004 |
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12148572 |
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Current U.S.
Class: |
523/118 |
Current CPC
Class: |
A61K 6/30 20200101; A61K
6/30 20200101; C08L 33/00 20130101; C08L 33/00 20130101; A61K 6/30
20200101; A61K 6/62 20200101; A61K 6/71 20200101 |
Class at
Publication: |
523/118 |
International
Class: |
A61K 6/00 20060101
A61K006/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 18, 2006 |
EP |
PCT/EP2006/010051 |
Claims
1. Non-aqueous dental adhesive comprising a mixture containing (i)
one or more polymerizable monomers optionally containing an acidic
group, (ii) a polymerization initiator, and (iii) a thermal
polymerization inhibitor of the following formula (I): ##STR00012##
wherein R'.sub.1 represents a hydrogen atom, or a saturated
hydrocarbon group having 1 to 18 carbon atoms. R'.sub.2, which may
be the same or different if more than one R'.sub.2 is present,
independently represent a saturated hydrocarbon group having 1 to
18 carbon atoms, and c represents an integer of from 1 to 4, (iv)
optionally an organic solvent.
2. The dental adhesive according to claim 1, which is stable at
storage for at least 10 days at 60.degree. C.
3. The dental adhesive according to claim 1 or 2, wherein the
saturated hydrocarbon group is a straight chain or branched
C.sub.1-18 alkyl group or a C.sub.3-8 cycloalkyl group optionally
substituted by one or more C.sub.1-5 alkyl groups or a C.sub.4-8
cycloalkylalkyl group optionally substituted by one or more
C.sub.1-5 alkyl groups.
4. The dental adhesive according to any one of the preceding
claims, wherein R'.sub.2 is a tert.-butyl group.
5. The dental adhesive according to any one of the preceding
claims, wherein the inhibitor is TBHQ or BHA.
6. The dental adhesive according to any one of the preceding
claims, wherein the inhibitor is contained in an amount of from
0.01 to 0.5 mol %.
7. The dental adhesive according to any one of the preceding
claims, wherein the aqueous mixture further contains an organic
water soluble solvent selected from the group of alcohols and
ketones such as ethanol, propanol, butanol, acetone, methyl ethyl
ketone.
8. The dental adhesive according to any one of the preceding
claims, wherein said polymerization initiator is a photo initiator
such as camphor quinone.
9. The dental adhesive according to any one of the preceding
claims, which further contains an inorganic filler and/or an
organic filler; preferably the filler is a nanofiller.
10. Use of a compound of the following formula (I): ##STR00013##
wherein R'.sub.1 represents a hydrogen atom, or a saturated
hydrocarbon group having 1 to 18 carbon atoms. R'.sub.2, which may
be the same or different if more than one R'.sub.2 is present,
independently represent a saturated hydrocarbon group having 1 to
18 carbon atoms, and c represents an integer of from 1 to 4, as a
thermal polymerization inhibitor in a dental composition.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a dental adhesive having
improved storage stability and low toxicity. The dental adhesive
may be a one-pack dental adhesive composition, in particular a
total etch dental adhesive. The present invention also relates to
the use of a specific thermal polymerization inhibitor in a dental
adhesive composition.
BACKGROUND OF THE INVENTION
[0002] Dental adhesive compositions known from the prior art
typically contain a mixture of a polymerizable monomer and an
initiator system in a suitable solvent. The activity of the
polymerizable monomers and the initiator system of the mixture must
be adapted to provide sufficient curing activity and adhesion on
dentin and enamel surfaces. However, an increased activity leads to
a complex stability problem during storage of the components of the
mixture. Specifically, the initiator system may be activated
leading to premature polymerization of the mixture.
[0003] As a result of the stability problem of the mixture, the
storage stability at room temperature of commercial dental adhesive
compositions known from the prior art may be insufficient. For
example, conventional commercial one-part self-etching,
self-priming dental adhesive compositions must be stored in a
refrigerator in order to avoid deterioration by solvolysis or
polymerization. The commercial composition "iBond Gluma inside" may
be mentioned, which has a low thermal stability when stored at
temperatures of 37.degree. C. or 50.degree. C. due to premature
polymerization within less than two weeks, which is indicative of
an insufficient thermal stability at room temperature for all
practical purposes. Similar stability problems are observed with
other dental adhesive compositions.
[0004] EP-A 1 548 021 suggests hydrolysis stable one-part
self-etching, self-priming dental adhesive compositions containing
specific monomers having improved resistance against hydrolysis
under acidic conditions. In order to improve the stability of the
initiator system, EP-A 1 548 021 suggests a stabilizer such as
hydroquinone monomethylether, 2,6-di-tert.-butyl-p-cresol,
tetramethyl piperidine N-oxyl radical and galvanoxyl radical.
However, generic one-part self-etching, self-priming dental
adhesive composition known from EP-A 1 548 021 still require
improvement of the thermal stability at storage for attaining a
stability of at least 10 days at 60.degree. C. required. Moreover,
hydroquinone is an allergenic compound imparting undesirable toxic
properties to a dental adhesive composition.
SUMMARY OF THE INVENTION
[0005] It is a problem of the present invention to provide a dental
adhesive composition having a low toxicity and thermal stability at
storage of at least 10 days at 60.degree. C.
[0006] Moreover, it is the problem of the present invention to
provide a specific class of compounds which may be used to
stabilize a dental adhesive composition for at least 20 days during
storage at 60.degree. C.
[0007] The present invention provides a non-aqueous dental adhesive
comprising a mixture containing
(i) one or more polymerizable monomers optionally containing an
acidic group, (ii) a polymerization initiator, (iii) a thermal
polymerization inhibitor of the following formula (I):
##STR00002## [0008] wherein [0009] R'.sub.1 represents [0010] a
hydrogen atom, or a saturated hydrocarbon group having 1 to 18
carbon atoms. [0011] R'.sub.2, which may be the same or different
if more than one R'.sub.2 is present, independently represent
[0012] a saturated hydrocarbon group having 1 to 18 carbon atoms,
and [0013] c represents an integer of from 1 to 4, and (iv)
optionally an organic solvent.
[0014] The present invention is based on the recognition that a
mixture containing
one or more polymerizable monomers optionally containing an acidic
group, one or more organic or inorganic acids, and a polymerization
initiator is problematic with regard to polymerization whereby
conventional stabilizers such as hydroquinone monomethylether,
2,6-di-tert.-butyl-p-cresol, tetramethyl piperidine N-oxyl radical
and galvanoxyl radical provide an insufficient effect for attaining
a high storage stability.
[0015] The present invention is furthermore based on the
recognition that a specific class of water insoluble stabilizers
provides a surprising stabilizing effect so that a dental adhesive
may be provided which has an excellent storage stability due to an
improved resistance against premature polymerization.
[0016] Accordingly, the present invention also relates to the use
of a compound of the following formula (I):
##STR00003## [0017] wherein [0018] R'.sub.1 represents [0019] a
hydrogen atom, or a saturated hydrocarbon group having 1 to 18
carbon atoms. [0020] R'.sub.2, which may be the same or different
if more than one R'.sub.2 is present, independently represent
[0021] a saturated hydrocarbon group having 1 to 18 carbon atoms,
and [0022] c represents an integer of from 1 to 4, as a thermal
polymerization inhibitor in a dental composition.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] The dental adhesive composition according to the present
invention contains a water-insoluble thermal polymerization
inhibitor of formula (I). Preferably, the saturated hydrocarbon
group which may be present as R'.sub.1 or R'.sub.2 in formula (I)
represents a straight chain or branched C.sub.1-8 alkyl group or a
C.sub.3-8 cycloalkyl group optionally substituted by one or more
C.sub.1-5, alkyl groups or a C.sub.4-18 cycloalkylalkyl group
optionally substituted by one or more C.sub.1-5 alkyl groups.
[0024] Preferably, R'.sub.1 represents a straight chain or branched
C.sub.1-18 alkyl group. In a preferred embodiment, R'.sub.1 is
hydrogen or a tert.-butyl group.
[0025] R'.sub.2 in formula (I) is believed to provide a steric
effect due to the bulky nature of the substituent in this position.
Therefore, at least one R'.sub.2 in formula (I) is a saturated
hydrocarbon group having 1 to 18 carbon atoms. Accordingly, in a
specific embodiment, at least one R'.sub.2 in formula (I)
represents a branched C.sub.3-18 alkyl group or a C.sub.4-8
cycloalkyl group optionally substituted by one or more C.sub.1-5
alkyl groups or a C.sub.4-18 cycloalkylalkyl group optionally
substituted by one or more C.sub.1-5 alkyl groups. More
specifically, at least one R'.sub.2 in formula (I) preferably
represents a branched C.sub.3-18 alkyl group or a C.sub.3-18
cycloalkyl group optionally substituted by one or more C.sub.1-5
alkyl groups. Even more specifically, at least one R'.sub.2 in
formula (I) preferably represents a branched C.sub.3-8 alkyl group.
In a further preferred embodiment, R'.sub.2 is a tert.-butyl
group.
[0026] c represents an integer of from 1 to 4, preferably 1 or 2.
In a specific embodiment, c is 1.
[0027] Preferably, thermal polymerization inhibitor is a compound
of the following formula (I'):
##STR00004##
wherein
[0028] R'.sub.1 represents a hydrogen atom, or a saturated
hydrocarbon group having 1 to 18 carbon atoms; R'.sub.2 represents
a saturated hydrocarbon group having 1 to 18 carbon atoms. Most
preferably, the inhibitor is tert.-butyl hydroquinone (TBHQ) or
tert.-butyl hydroxyanisole (BHA).
[0029] Preferably, the inhibitor is contained in the dental
adhesive composition in an amount of from 0.01 to 0.5 mol %, more
preferably in an amount of from 0.05 to 0.3 mol %.
[0030] The dental adhesive composition according to the present
invention contains a polymerizable monomers optionally containing
an acidic group.
[0031] The polymerizable monomers in the dental adhesive
composition according to the invention are capable of free-radical
polymerization and are preferably (meth)acrylate monomers or
oligomers. The dental adhesive according to the invention may
contain a polymerizable monomer or oligomer as a mixture of
different compounds or as isomers of the same compound. The
polymerizable monomer or oligomer may include a derivative of at
least one unsaturated carboxylic acid selected from the group
consisting of acrylic acid, methacrylic acid, cyanoacrylic acid and
itaconic acid, and mixtures thereof, a derivative of styrene, or a
polymerizable moiety containing a carbon-carbon double bond
conjugated with a carbonyl group.
[0032] The (meth)acrylate monomer or oligomer is selected from
materials having at least one, and preferably two to four
polymerizable double bonds per molecule so that the cured dental
adhesive be crosslinked and thus better suited for use in the oral
cavity. Monomers with a single polymerizable double-bond may be
used in order to adjust the viscosity of the composition.
(Meth)acrylate monomer materials useful herein are well known in
the art. The preferred materials generally include monomers having
a central portion containing an organic moiety and at least two
(meth)acrylic end groups. Desirable characteristics for such
monomers and/or oligomers include good film forming properties, low
viscosity, low polymerization shrinkage, low water sorption and the
ability to cure rapidly and completely in the mouth. It is also
desirable that the monomers be low in volatility and non-irritating
to the tooth pulp. A mixture of two or more appropriate
methacrylate monomers is within the scope of this invention. In
fact, depending on the choice of monomers, mixture are often highly
desirable to optimize the characteristics of the resulting dental
composition.
[0033] The polymerizable monomer or oligomer may also be selected
from the group consisting of hydroxyethyl acrylate, hydroxypropyl
acrylate, diurethane dimethacrylate resin, hydroxyethyl
methacrylate, hydroxypropyl methacrylate, trimethylolpropane
triacrylate, 1,6-hexanediacrylate, glycerin diacrylate,
triethyleneglycol diacrylate, tetraethyleneglycol diacrylate, and
2-acrylamido-2-methyl-1-propansulfonic acid, a reaction product of
butane tetracarboxylic acid dianhydride and
hydroxyethylmethacrylate, triethyleneglycol dimethacrylate,
urethane dimethacrylate, and a reaction product of butane
tetracarboxylic acid dianhydride and glycerol dimethacrylate, or
acrylamides or derivatives thereof such as
2-acrylamido-2-methylpropane sulphonic acid,
N,N-methylene-bis-acrylamide, N,N-ethylene-bis-acrylamide, and
1,3-bis(acrylamido)-N,N-diethylpropane.
[0034] The polymerizable monomer or oligomer may be a phosphate
based acid adhesion promoter selected from the group consisting of
phosphate ester or phosphonate derivatives of radical polymerizable
alcohol or polyol derivatives. The phosphate ester derivatives may
be prepared using the method given in U.S. Pat. No. 4,514,342. As
examples of suitable carboxylic acid based adhesion promoters may
be mentioned the reaction product between butanetetracarboxylic
acid dianhydride and hydroxylethyl acrylate as in U.S. Pat. No.
5,218,070. Various radical polymerizable acidic monomers useful as
adhesion promoters may also be obtained by many other means, for
instance as given in U.S. Pat. No. 4,806,381 and U.S. Pat. No.
6,350,839.
[0035] The polymerizable monomer or oligomer may further be a
carboxylic acid based adhesion promoter selected from the group
consisting of reaction products between acid anhydrides and radical
polymerizable derivatives of alcohols. The acid anhydride may be
selected from the group consisting of butanetetracarboxylic acid
dianhydride, tetrahydrofurantetracarboxylic acid dianhydride,
benzenetetracarboxylic acid dianhydride and benzentricarboxylic
acid an hydride. The radical polymerizable derivatives of alcohols
may be selected from the group consisting of hydroxyethyl acrylate,
hydroxypropyl acrylate, glycerol diacrylate, pentaerythritol
triacrylate, dipentaerythritol pentaacrylate, hexanediol acrylate,
polyethylenoxide acrylate, and triallypentaerythritol.
[0036] These may be mono- or polyfunctional acrylates and
methacrylates, of the kind described, for example, in EP-A-0 480
472. Moreover, functionalized monomers with terminal acrylate or
methacrylate groups may likewise be used, of the kind described,
e.g., in DE-A-2 312 559 and in EP-A-0 219 058.
[0037] The dental adhesive according to the present invention may
contain polymerizable monomers in an amount of from 5 to 90 wt-%,
preferably in an amount of from 20 to 70 wt. %.
[0038] It is preferred that the monomer or oligomer or monomer or
oligomer blend has a viscosity of at most 100 Pas at 23.degree. C.,
more preferably at most 5 Pas.
[0039] The dental adhesive composition according to the invention
may optionally comprise an organic solvent. In a preferred
embodiment, the dental adhesive contains one or more further
solvents selected from conventional inert solvents such as
short-chain alcohols, short-chain ketones, aliphatic or unsaturated
ethers, and cyclic ethers conventionally used in the dental field.
Preferred solvents are selected from acetone, ethanol and
t-butanol. The dental adhesive composition may contain the solvent
in an amount of from 10 to 95 wt. %.
[0040] The dental adhesive composition according to the present
invention may further comprise an initiator. A chemical initiator
may be used in case of a multicomponent composition. The chemical
initiator is able to form radicals by mixing at least two
chemically different substances, which have to be stored
separately, without a further input of energy, which radicals are
then able to initiate a polymerization reaction. Examples of such
chemical initiator systems are peroxy amine or peroxy proton
donor/metal compound mixtures, of the kind described by J. M.
Antonucci et al. in J. Dental Research (1979), 58 (9), page
1887-1889 or in U.S. Pat. No. 5,166,117 and in EP-A-0 115 410, 0
115 948, 0 120 559 and 0 277 413. More preferred are initiators
capable of forming radicals without mixing of different components,
but based on input of energy such as thermal or light energy. In
this case, the dental adhesive composition may be a one-component
dental adhesive composition, wherein the initiator is a
photoinitiator and/or a thermal initiator. The composition may
comprise an alpha-diketone such as camphor quinone.
[0041] The dental adhesive may further contains an inorganic filler
and/or an organic filler; preferably the filler is a nanofiller. A
filler may be contained in an amount of from 0.5 to 20 wt. %, more
preferably 2 to 10 wt. %.
[0042] A one-pack composition means that the composition of the
present invention is contained in only one container which may be
stored and allows application of the composition without any mixing
and without any special equipment before the application.
[0043] A total etch composition is a one-pack composition having
priming and bonding activity on a dental surface such as dentin or
enamel.
[0044] The invention will now be further illustrated with reference
to the following examples
EXAMPLES
[0045] Test Formulation containing different inhibitors.
[0046] A series of test formulations containing different thermal
polymerization inhibitors was prepared in order to illustrate the
surprising thermal stability of a dental adhesive composition
according to the present invention. The standard composition was
used as follows:
TABLE-US-00001 Component Content (wt.-%) BAP 63.2 BAA-TCD 21.1
DHPOBA_analog 54.2 2-Acrylamido-2-methyl- 43.8 propanesulfonic acid
(AMPS) Camphor Quinone 1.3 TPO 3.2 DMABE 1.5 Total 100.00 Active
Matrix 55 Acrylic acid 9 Water 36 Total 100
[0047] The following comparative inhibitors were tested:
(i) hydroquinone (HQ), (ii) hydroquinone monomethylether (HQME),
(iii) bisphenol A, (iv) propyl gallate (PG)
[0048] The following inhibitors according to the present invention
were tested:
(vii) tert-Butylhydroquinone (TBHQ), and (viii)
tert.-Butylhydroxyanisol (BHA).
##STR00005##
[0049] Test formulations containing different inhibitors or
inhibitor concentrations were stored in Prime&Bond NT bottles
(Dentsply DeTrey) at 60.degree. C. until thermal polymerization.
The bottles were daily examined by shaking the bottle, whereby the
acoustical test turned out to be rather sensitive, and by taking a
sample with a pipette. When polymerization seemed to have occurred
or after a certain minimum storage time (20 days) the bottles were
sliced open and the solution were examined visually.
[0050] According to the results of the above described Arrhenius
investigation at least a thermal stability of about 11 days at
60.degree. C. is necessary so that the dental adhesive composition
may be stored at room temperature.
Results
[0051] The Test Formulation containing different inhibitors in
different amounts, was investigated regarding its thermal stability
by storing these formulations at 60.degree. C. The samples were
daily examined. In case of polymerization a gel or a solid,
polymerized body was observed.
[0052] The dark shaded columns represent formulations with
inhibitors, respectively inhibitor concentrations, which were
polymerized after the depicted time at 60.degree. C. The light
shaded columns represent formulations, which were not polymerized
until the depicted time. Usually after 20 days the investigation
was terminated.
[0053] In the comparison, hydroquinone (HQ) was used in an amount
of 0.15 mol % showing some stabilization effect. However,
hydroquinone is an allergenic compound and therefore undesirable
for use in a generic dental composition. Hydroquinone
monomethylether (HQME) as well as BHT failed to provide a
sufficient thermal stability.
(i) Hydrochinone (HQ)--Reference Inhibitor
TABLE-US-00002 ##STR00006##
[0054] (light shaded columns--formulation is not polymerized up to
the recorded time; dark shaded column: formulation is polymerized
after the recorded time)
(ii) Hydrochinone Monomethylether (HQME)--Reference Inhibitor
TABLE-US-00003 ##STR00007##
[0056] After slicing open the samples containing 0.49 and 0.697 mol
% HQME, small pieces of gel were found at the bottom, which were
not detected before by shaking or by the examination with the
pipette.
[0057] After slicing open the sample with 0.193 mol % TBC some
pieces of gel were found at the bottom, which were not detected
before by shaking or by the examination with the pipette.
(iii) Bisphenol A--Reference Inhibitor
TABLE-US-00004 ##STR00008##
(the dark shaded columns indicate that the formulation is
polymerized after the recorded time)
(iv) Propyl Gallate (PG)--Reference Inhibitor
TABLE-US-00005 ##STR00009##
[0059] The dark shaded columns indicate that the formulation is
polymerized after the recorded time
(vii) tert.-Butylhydrochinone (TBHQ)--Inhibitor of the
Invention
TABLE-US-00006 ##STR00010##
[0060] After 14 days and after 20 days at 60.degree. C. the bottles
were sliced open, the contents was investigated and filled in a new
bottle, which was stored again at 60.degree. C. No hints of a
polymerization were found.
[0061] After 20 days at 60.degree. C. the bottles were sliced open
again and the contents was investigated. Only in case of the lowest
TBHQ percentage of 0.013 mol % polymerization was found. This was
not detected before by the daily examination.
(viii) tert.-Butylhydroxyanisole (BHA)--Inhibitor of the
Invention
TABLE-US-00007 ##STR00011##
[0062] After 14 days at 60.degree. C. all bottles were sliced open,
the contents was investigated and filled in a new bottle, which was
stored again at 60.degree. C. The sample with 0.047 mol % showed
after 14 days at 60.degree. C. some pieces of gel, which were not
detected before by shaking or by the examination with the pipette.
After 20 days at 60.degree. C. the bottles were again sliced open.
No indication of polymerization for the samples containing 0.096
mol % and 0.147 mol % were found. The formulation with 0.047 mol %
again contains some small pieces of gel.
Example 1
[0063] The following non-aqueous compositions were prepared with
different amounts of TBHQ as an inhibitor. The compositions were
stored at 65.degree. C. The time required for polymerization and
therefore deterioration of the composition was determined.
TABLE-US-00008 Composition/wt.-% Polymerizable Resins 67.33 67.29
67.25 67.21 CQ/Amine 2.67 2.67 2.67 2.67 TBHQ 0.04 0.08 0.12 0.16
Nanofiller 5.47 5.47 5.47 5.47 t-Butanol 24.5 24.5 24.5 24.5 Sum
100 100 100 100 Days life to polymerization Temp./.degree. C. t/d
t/d t/d t/d 65 4 10 77 >77
[0064] It was found that 0.028-0.2 mol % TBHQ provides a sufficient
thermal stability over 20 days at 65.degree. C.
Comparison Example 1
[0065] The following non-aqueous compositions were prepared with
different amounts of BHT as an inhibitor. The compositions were
stored at 65.degree. C. The time required for polymerization and
therefore deterioration of the composition was determined.
TABLE-US-00009 Composition/wt.-% Polymerizable Resins 35.35 66.87
68.11 53.15 CQ/Amine 1.41 2.67 1.43 2.12 BHT 0.26 0.49 0.49 0.39
Nanofiller 2.89 5.47 5.47 4.35 t-Butanol 60.09 24.50 24.50 40 Sum
100 100 100 100 Days life to polymerization Temp./.degree. C. t/d
t/d t/d t/d 65 1 1 6 4
[0066] It was found that 0.028-0.2 mol % BHT does not provide a
sufficient thermal stability over 20 days at 65.degree. C.
Comparison Example 2
[0067] The following non-aqueous compositions were prepared with
different amounts of PG as an inhibitor. The compositions were
stored at 65.degree. C. The time required for polymerization and
therefore deterioration of the composition was determined.
TABLE-US-00010 Composition/wt.-% Polymerizable Resins 67.31 67.26
67.21 67.16 CQ/Amine 2.67 2.67 2.67 2.67 PG 0.05 0.10 0.15 0.2
Nanofiller 5.47 5.47 5.47 5.47 t-Butanol 24.5 24.5 24.5 24.5 Sum
100 100 100 100 Days life to polymerization Temp./.degree. C. t/d
t/d t/d t/d 65 0-3 0-3 0-3 0-3
[0068] It was found that 0.028-0.2 mol % PG does not provide a
sufficient thermal stability over 20 days at 65.degree. C.
Example 2
[0069] 0.6945 g N,N'-Bisacrylamido-N,N'-diethyl-1,3-propane, 0.2315
g 3,(4),8,(9)-bis(acrylamido methyl)tricyclo-5.2.1.0.sup.2,6
decane, 0.0595 g Ethyl 2-[12-dihydrogen
phosphoryl-12,2-dioxamidecyl]acrylate, 0.0481 g
2-Acrylamido-2-methyl-propane-sulfonic acid, 0.0141 g camphor
quinone, 0.0355 g bis(2,4,6-trimethylbenzoyl)-phenyl phosphine
oxide, 0.0164 g dimethylamino benzoic acid ethyl ester and 0.003 g
2-tert-Butylhydroquinone were dissolved in a solvent mixture
composed of 0.1800 g acrylic acid and 0.7200 g water.
[0070] The adhesive does not polymerise after storage for 20 days
at 60.degree. C.
Example 3
[0071] 0.6940 g N,N'-Bisacrylamido-N,N'-diethyl-1,3-propane, 0.2313
g 3,(4),8,(9)-bis(acrylamido methyl)tricyclo-5.2.1.0.sup.2,6
decane, 0.0595 g Ethyl 2-[12-dihydrogen
phosphoryl-12,2-dioxamidecyl]acrylate, 0.0481 g
2-Acrylamido-2-methyl-propane-sulfonic acid, 0.0141 g camphor
quinone, 0.0355 g bis(2,4,6-trimethylbenzoyl)-phenyl phosphine
oxide, 0.0164 g dimethylamino benzoic acid ethyl ester and 0.0011 g
2-tert.-butyl-4-methoxyphenol were dissolved in a solvent mixture
composed of 0.1800 g acrylic acid and 0.7200 g water. The adhesive
does not polymerise after storage for 20 days at 60.degree. C.
Comparative Example 3
[0072] 0.6931 g N,N'-Bisacrylamido-N,N'-diethyl-1,3-propane, 0.2310
g 3,(4),8,(9)-bis(acrylamido methyl)tricyclo-5.2.1.0.sup.2,6
decane, 0.0594 g ethyl 2-[12-dihydrogen
phosphoryl-12,2-dioxamidecyl]acrylate, 0.0480 g
2-Acrylamido-2-methyl-propane-sulfonic acid, 0.0141 g camphor
quinone, 0.0354 g bis(2,4,6-trimethylbenzoyl)-phenyl phosphine
oxide, 0.0164 g dimethylamino benzoic acid ethyl ester and 0.0026 g
hydroquinone monomethyl ether were dissolved in a solvent mixture
composed of 0.1800 g acrylic acid and 0.7200 g water.
[0073] The adhesive polymerises after storage for 1 day at
60.degree. C.
Comparative Example 4
[0074] 0.6882 g N,N'-Bisacrylamido-N,N'-diethyl-1,3-propane, 0.2294
g 3,(4),8,(9)-bis(acrylamido methyl)tricyclo-5.2.1.0.sup.2,6
decane, 0.0590 g Ethyl 2-[12-dihydrogen
phosphoryl-12,2-dioxamidecyl]acrylate, 0.0477 g
2-Acrylamido-2-methyl-propane-sulfonic acid, 0.0140 g camphor
quinone, 0.0352 g bis(2,4,6-trimethylbenzoyl)-phenyl phosphine
oxide, 0.0162 g dimethylamino benzoic acid ethyl ester and 0.0103 g
2,6-di-tert.-butyl-4-cresol were dissolved in a solvent mixture
composed of 0.1800 g acrylic acid and 0.7200 g water. The adhesive
polymerises after storage for 2 days at 60.degree. C.
* * * * *