Polymerizable compositions comprising polyamines and poly(dihydrobenzoxazines)

A polymerizable composition comprising a poly(3,4-dihydro-3-substituted-1,3 benzoxazine) and a reactive polyamine, wherein the polyamine is at least difunctional and its reactive groups are primary or secondary amine and wherein the poly(dihydrobenzoxazine) is the reaction product of about 1 equivalent of a primary amine, about 1 equivalent of a phenol and about two equivalents of formaldehyde. The compositions are useful as potting, encapsulating and laminating resins and as surface coatings.

This invention relates to compositions comprising poly(dihydrobenzoxazines) 
and polyamines containing primary or secondary amine groups. The invention 
further relates to methods of curing the compositions of the invention and 
to the resultant cured products and to their use as protective coatings. 
W. J. Burke et al (J. Org. Chem 30, 3423 (1965) and J. L. Bishop (Thesis, 
Univ. of Utah 1962) describe the potential reactions of 
dihydro-1,3-benzoxazines with a number of different types of compounds 
(HY) characterized by the presence of a highly nucleophilic carbon or 
nitrogen atom. 
##STR1## 
These ring opening aminoalkylation reactions as described by Burke and 
Bishop do not liberate volatiles. The reaction aptitude depends both on 
the structure of the 1,3-dihydrobenzoxazine and on the structure of the 
nucleophile containing molecule. Burke and Bishop do not include primary 
amines among the HY compounds, or secondary amines except for the 
heterocyclic secondary amines, indole and carbazole which are incapable of 
providing polymerization systems. No polymerization reactions of 
dihydrobenzoxazines are described. 
Rigterink describes the formation of poly(dihydrobenzoxazines) from various 
combinations of polymethylene diamines and phenols (U.S. Pat. No. 
2,826,575) and from amines with bis-phenols (U.S. Pat. No. 2,825,728). 
These materials were used as parasiticides. 
Burke et al (J. Am. Chem. Soci., 72, 4691 (1950) and J. Org. Chem., 26, 
4403 (1961)) and Kuehne et al (J. Med. Pharm. Chem., 5, 257 (1962)) 
describe the formation of poly(dihydrobenzoxazines) of polyhydric phenols 
and amines but do not discuss the polymerization of these 
poly(dihydrobenzoxazines) or their reaction with amines. 
H. Schreiber (British Pat. No. 1,437,814) describes the preparation and use 
of dihydrobenzoxazine polymers and prepolymers. These materials are 
relatively slow curing by themselves and in the presence of resins and 
polymerizable compounds. Specifically, the heating of these materials both 
alone and with epoxy resins typically provides gel times of several hours 
at temperatures &gt;100.degree. C. 
The present invention provides a composition comprising a reactive 
polyamine and a poly(3,4-dihydro-3-substituted-1,3-benzoxazine). The 
reactive polyamine contains primary and/or secondary amine groups which 
react with the dihydrobenzoxazine groups of the poly(hydrobenzoxazine) to 
cure the composition. The poly(dihydrobenzoxazines) are oligomeric 
mixtures wherein the majority of individual molecules contain at least two 
3,4-dihydro-3-substituted-1,3-benzoxazine moieties. 
The compositions of the invention cure more rapidly than 
dihydrobenzoxazines cured by themselves or in previously disclosed 
combination with other polymerizable compounds such as epoxides. For 
example the poly(dihydrobenzoxazines) are capable of reacting with primary 
or secondary amines in the temperature range of about 25.degree. to about 
200.degree. C. in times less than 30 minutes. The reaction between a 
dihydrobenzoxazine and an amine generates very little volatile matter 
since it involves a ring opening aminoalkylation reaction. Further, 
poly(dihydrobenzoxazines) can be selected which have long pot lives when 
combined with primary and/or secondary amine containing polyamines but 
which react rapidly and efficiently at elevated temperatures. This 
contrasts with most epoxy resin systems combined with polyamines which 
have a relatively brief pot life. The polyamines can be readily modified 
to increase pot life even more when used in combination with 
dihydrobenzoxazines. Other aspects of the invention are directed to the 
method of curing the compositions of the invention, to the resultant cured 
products and to their use as protective coatings. Curing can be achieved 
over a broad pH range from moderately acid to highly basic. The only 
limitation for cure pH may be at low pH values where acid hydrolysis of 
the dihydrobenzoxazine ring can occur and protonation of the amine by the 
acid can retard reaction. 
Depending on the structure of the polyamine and poly(dihydrobenzoxazine) a 
wide range of desirable cured properties are obtained in the cured 
composition including chemical resistance, toughness, flexibility and 
hardness. When the compositions of the invention are applied as coatings 
to metallic substrates and cured they provide good corrosion resistance to 
the substrates. 
The ring opening aminoalkylation reaction of 3,4-dihydro-1,3 benzoxazine 
with an amine group produces a methylene diamine linkage. 
##STR2## 
This methylene diamine bridge consisting of a single carbon joining two 
amine groups forms the major polymerization linkage when 
poly(dihydrobenzoxazines) are reacted with polyamines. Amine compounds 
where two amine nitrogen atoms are joined to a single carbon atom are 
generally regarded to be unstable and can usually be isolated only as 
their acid salts or in complex cyclic ring structures such as 
hexamethylene tetramine. In contrast, the cured compositions of the 
present invention comprising such diamine bridges possess surprising 
toughness, durability and excellent chemical resistance to solvents and 
corrosive environments. Thermal resistance of the cured systems is more 
than adequate for conventional protective coating applications. 
The dihydrobenzoxazines are prepared by the condensation of a phenol, a 
primary amine and formaldehyde, the condensation product being 
substantially formaldehyde free and incapable of generating formaldehyde 
at the curing step. The base strength pK.sub.b of the primary amines may 
be in the range of 3 to 13. The poly(dihydrobenzoxazines) prepared from 
aromatic amines with pK.sub.b &gt;7, generally yield mixtures and solutions 
with polyamines which are more stable at room temperature yet cure more 
completely at lower temperatures than compositions of polyamines and 
poly(dihydrobenzoxazines) derived from more basic amines with pK.sub.b &lt;7. 
This result runs contrary to the well known generalization that the 
aminoalkylation aptitude of a dihydrobenzoxazine increases with basicity 
of the amine from which the oxazine is derived. 
Poly(dihydrobenzoxazine) compounds suitable for admixture with polyamine 
compounds to provide the uncured compositions of the present invention can 
be prepared by a variety of techniques from many types of coreactants. 
Many of the preferred dihydrobenzoxazines are oligomeric mixtures wherein 
the majority of individual molecules contain at least two 
3,4-dihydro-3-substituted-1,3-benzoxazine groups. The dihydrobenzoxazines 
can be made by reacting about one equivalent of an amine containing at 
least two primary groups with about two equivalents of formaldehyde and 
about one equivalent of a monophenol containing at least one unsubstituted 
ortho position. Suitable di-primary amines include hydrazine, and C.sub.2 
to C.sub.40 unsubstituted and substituted di-primary amines such as 
bis(aminophenyl)alkanes, diaminobenzenes, diaminoalkanes, 
diaminocycloalkanes and various polyoxyalkylene diamines. Suitable 
polyamines include poly(aminophenyl)alkanes, alkane polyamines and 
polyoxyalkylene polyamines. Diaminobenzenes and bis(aminophenyl)alkanes 
are preferred amino reactants. The optional substituents of these di- and 
polyamines include alkyl, alkoxy, aryl and halo substituents. Examples of 
suitable phenols include C.sub.6 to C.sub.20 phenols such as phenol, alkyl 
phenols, alkoxy phenols, aryl phenols, halophenols, naphthols and other 
aromatic hydroxy materials which have at least one unsubstituted position 
ortho to each hydroxy group and which may contain substituents which do 
not substantially deactivate these unsubstituted ortho positions and do 
not react with primary amine groups, such as alkyl, alkoxy, aryl or halo 
substituents. 
A second method for making poly(dihydrobenzoxazines) is by the reaction of 
an unsubstituted or substituted primary amine, and formaldehyde with a 
C.sub.6 to C.sub.30 polyphenol containing at least two hydroxysubstituted 
aromatic rings each with at least one unsubstituted position ortho to each 
hydroxy group optionally containing substituents such as alkyl, alkoxy, 
aryl or halo substituents which do not substantially deactivate the 
unsubstituted ortho positions and do not react with primary amines. The 
reaction ratio is typically about one equivalent of such polyphenol to one 
equivalent of primary amine, and two equivalents of formaldehyde. The 
primary amines may contain alkyl, alkoxy, aryl or halo substituents. 
Suitable primary amines contain from one to twenty carbon atoms and 
include aminoalkanes, aminocycloalkanes, aminoalkenes, amino glycols, and 
arylamines such as aniline and naphthylamine. Aniline and substituted 
anilines are preferred amine reactants. Suitable polyphenols include 
hydroquinone, resorcinol and catechol, biphenols, naphthalenediols, 
phloroglucinol, bisphenols, novolac resins prepared from phenol and 
substituted phenols, and the alkyl, alkoxy, aryl and halo substituted 
derivatives of these polyphenols. Preferred polyphenols include 
hydroquinone, bisphenol A, bis(4-hydroxyphenyl)methane, 4-hydroxyphenyl 
ether, 4-hydroxyphenyl sulfone, and 4,4'-bisphenol. 
A third method for preparing poly(dihydrobenzoxazines) is provided by the 
reaction of a mixture of any of the above listed monophenols and/or 
polyphenols with a mixture of any of the above listed monoamines and/or 
polyamines and formaldehyde to form oligomers of average molecular weight 
in the range of about 300 to about 2000, containing an average of at least 
about two dihydro-1,3-benzoxazine moieties per molecule. Many reaction 
combinations are possible but to maximize dihydrobenzoxazine formation, 1 
phenol group and 2 molecules of formaldehyde should be present for each 
amine group in the reaction mixture. 
The poly(dihydrobenzoxazine) portion of the composition of the present 
invention can consist of one type of dihydrobenzoxazine or a mixture of 
dihydrobenzoxazines derived from different phenols and/or different 
amines. These mixtures can be obtained either by blending already formed 
dihydrobenzoxazines or by forming mixed dihydrobenzoxazine products by 
using a blend of reactants as set forth hereinabove. 
Generally in the preparation of dihydrobenzoxazine prepolymers 100% 
conversion of the amine reactant to dihydrobenzoxazine does not occur 
because of side reactions. The products of the side reaction are for the 
most part characterized by the formation of dibenzyl amine linkages 
between the ortho and para positions of adjacent phenol rings. Once these 
dibenzyl amine linkages form it becomes impossible for the bridged amine 
group to participate in heterocyclic dihydro-1,3-benzoxazine ring 
formation. For example, products typically formed from diamines with 
monophenol and formaldehyde or from diphenols with monoamines and 
formaldehyde, will contain the expected bis(dihydrobenzoxazines), but will 
also contain lesser amounts of higher molecular weight oligomers typically 
having at least two terminal dihydrobenzoxazine groups but also having one 
or more internal dibenzylamine linkage. Typical products made by the 
disclosed method will have 50 to 95% of the amine groups in the 3-position 
of the dihydrobenzoxazine ring. The remaining 5 to 50% of the amine groups 
will be principally in the form of dibenzylamine bridging. Another side 
reaction which can occur during and after dihydrobenzoxazine formation is 
the condensation of a formed dihydrobenzoxazine ring with a 
non-heterocyclized phenol ring containing an unreacted ortho or para ring 
position via an aminoalkylation reaction. This ring opening addition 
reaction results in dibenzylamine formation. These side reactions increase 
the molecular weight and may decrease the dihydrobenzoxazine functionality 
causing undesirable effects in the two component compositions of the 
present invention. These undesirable effects include reduced pot life and 
higher viscosity. Other side reactions are the conventional condensation 
of formaldehyde with phenols to form methylol groups and methylene 
bridges. These side reactions are controlled by the reaction method set 
forth herein. 
My preferred method for making dihydrobenzoxazines for use in this 
invention involves combining the phenol, amine and formaldehyde in the 
presence of a process solvent at temperatures which minimize the side 
reaction products. Aqueous formaldehyde can be added to a solution of 
amine and the phenol in the process solvent. In cases where the amine e.g. 
hexamethylene diamine reacts initially with formaldehyde to form 
crosslinked amine formaldehyde intermediates which are difficult to 
redissolve, it is preferable to make a dispersion of the phenol, process 
solvent and formaldehyde and add the amine or a solution of amine slowly 
to this dispersion. The process solvent is selected on the basis of its 
ability to dissolve the poly(dihydrobenzoxazine) reaction product and form 
immiscible phases with water and/or form azeotropic compositions with 
water. It is also desirable if possible for the process solvent to be a 
solvent for the two-component systems disclosed in this invention. 
Preferred solvents include methylene chloride, toluene, xylene and 
n-butanol or mixtures of these with themselves or other solvents. Many 
other solvent choices are possible. Other solvents can be added at the end 
of the process to make the poly(dihydrobenzoxazine) compatible with the 
polyamine component and to meet the requirements of the end use. 
Formaldehyde can be introduced in any of the forms which provide or 
generate formaldehyde such as aqueous formalin, formaldehyde in methanol, 
solid paraform or trioxane. Generally, concentrated aqueous formaldehyde 
solutions are preferred for economic reasons, but alcoholic formalin is 
often desirable when solubility problems are encountered durng 
poly(dihydrobenzoxazine) formation. It is generally preferable to combine 
the reactants below 55.degree. C. to minimize the undesirable side 
reaction of formaldehyde condensing with phenol to form methylol groups 
which can generate cure volatiles at the time of use. Such side reactions 
can also be minimized by reacting the primary amine with formaldehyde to 
form an amine formaldehyde intermediate product which is then reacted with 
the phenol to form the dihydrobenzoxazine. 
There is a distinct difference in the sensitivity of different 
dihydrobenzoxazine compositions to side reactions during processing. 
Dihydrobenzoxazines made from amines which are more basic (pK.sub.b &lt;7) 
are more sensitive to side reactions during processing and consequently 
give lower dihydrobenzoxazine yields. Advantageously these 
dihydrobenzoxazines are processed in a temperature range of 20.degree. to 
70.degree. C. Dihydrobenzoxazines based on amines with pK.sub.b &gt;7 are 
less subject to side reactions and are advantageously processed in the 
40.degree. C. to 120.degree. C. range. Advantageously after the addition 
of the reactants, which is done at the low end of the appropriate 
temperature range, the reaction is refluxed at an intermediate temperature 
in the appropriate range to maximize dihydrobenzoxazine formation. The 
reaction is then completed by removing water and unreacted monomers and 
possibly solvent at the middle to high temperature point of the 
appropriate reaction range. With a process solvent such as methylene 
chloride, the completed reaction mixture separates into two layers and the 
upper aqueous layer can be withdrawn. The methylene chloride and remaining 
water can then be removed by vacuum distillation. It is generally 
preferable to remove water by azeotropic distillation to increase the 
extent of reaction of the components forming the dihydrobenzoxazine and to 
minimize the loss of organic materials in the water layer. It is generally 
advantageous to use a stoichiometric excess of formaldehyde. This excess 
improves the conversion. An excess of 1 to 5% is preferable. The excess 
unreacted formaldehyde can be very efficiently removed with the water 
removed from the reaction mixture. Stripping of water and process solvent 
under reduced pressure also effectively removes unreacted formaldehyde. It 
is also sometimes desirable to use a slight excess in the range of about 1 
to about 5 percent of the primary amine used to form the 
dihydrobenzoxazine above 1 equivalent for each phenolic hydroxyl. However, 
at least 2 equivalents of formaldehyde based on the total amine should be 
present to react with the amine. 
The specific composition of the phenol and amine used to form the 
poly(dihydrobenzoxazine) can also significantly affect the yield and the 
potential for side reactions. For example, a para alkyl substituted phenol 
reactant reduces the level of ring opening amino alkylation side 
reactions. 
The resulting poly(dihydrobenzoxazines) are also different in their 
property behavior depending on whether or not they are formed from a 
strongly basic or a weakly basic amine. Table I compares the 
characteristics of poly(dihydrobenzoxazines) in these two categories 
manifested during manufacture and use. However, the presence of various 
substituents on the benzoxazine molecule can alter strict adherence to 
these categorized characteristics. 
TABLE I 
______________________________________ 
Comparison of Poly(dihydrobenzoxazines) Prepared 
from Strongly Basic Amines and Weakly Basic Amines 
Poly(dihydrobenzoxazines) 
Poly(dihydrobenzoxazines) 
from amines with pK.sub.b &lt;7 
from amines with pK.sub.b &gt;7 
______________________________________ 
More subject to side 
Less subject to side 
reactions during and 
reactions during and 
after preparation. 
after preparation. 
Lower dihydrobenzoxazine 
Higher dihydrobenzoxazine 
yield yield. 
Sensitive to aging in 
Not sensitive to aging 
polar and protic in polar and non polar 
solvents. Less solvents. 
sensitive to aging 
in non polar solvents. 
Stable as 100% solids 
Stable as 100% solids 
at 25.degree. C. at 25.degree. C. 
More sensitive to ring 
Less sensitive to ring 
opening aminoalkylation 
opening aminoalkylation 
reaction. reaction. 
More sensitive to acids 
Less sensitive to acids 
and hydrolysis of and hydrolysis of 
dihydrobenzoxazine ring. 
dihydrobenzoxazine ring. 
More tendency to form high 
Less tendency to form 
viscosity association 
high viscosity 
products with polyamine 
association products 
components in solution. 
with polyamine components 
in solution. 
Tendency toward short pot 
Tendency toward long pot 
life when blended with 
life when blended with 
polyamines. polyamines. 
______________________________________ 
There is probably not a sharp demarcation with increasing pK.sub.b but a 
gradual transition. In respect to these differences and the fact that the 
dihydrobenzoxazines derived from weakly basic amines show greater 
stability and are more resistant to side reactions and aging effects, it 
is an unexpected and a surprising result of this invention that these 
weakly basic amine products will react as fast or faster and often more 
completely than the strongly basic amine products with the polyamine 
components of the two component systems of the present invention. 
Purified dihydrobenzoxazine oligomers can be used in the practice of this 
invention but they generally offer no significant advantages over the 
oligomers containing controlled levels of side reaction products. Also 
they are not as economical to make and consequently not as commercially 
viable. 
The coreactants for dihydrobenzoxazines which provide the second component 
of the compositions of this invention include a large variety of compounds 
which contain primary or secondary amine groups. Advantageously, such 
polyamines contain at least two primary and/or secondary amine groups per 
molecule, have molecular weights in the range of about 58 to about 15,000 
and have amine equivalent weights in the range of about 29 to about 1500. 
Preferably the polyamines are oligomers of molecular weight in the range 
of about 100 to about 5,000 and have amine equivalent weights in the range 
of about 50 to about 1000. The rate of cure of the compositions of the 
present invention can be regulated by adjusting the ratio of primary to 
secondary amine groups in the polyamine molecule. For fast rate of 
reaction of the polyamine compound with the dihydrobenzoxazine component, 
the majority of the amine groups of the polyamine should be primary. 
Moreover the position and environment of the amine groups in the polyamine 
can be important since steric hinderance can influence the rate of 
reaction. 
Low molecular weight polyamines which can be used as crosslinkers or 
hardeners for poly(dihydrobenzoxazines) include those C.sub.2 to C.sub.40 
amines typically classed as curing agents for epoxy resins. These include 
the alkane polyamines such as ethylene diamine, diethylene triamine, 
triethylene tetraamine, hexamethylene diamine, trimethylhexamethylene 
diamine, bis-hexamethylene triamine and triaminononane; the 
polyamino-cycloalkanes such as isophorone diamine, 
bis(aminomethyl)norbornane, and diaminocyclohexanes; the 
polyoxypropyleneamines commercially known by the tradename "Jeffamines", 
(sold by Jefferson Chemical Co., Inc. a subsidiary of Texaco Inc.) the 
polyamines based on heterocyclic backbones such as 
1,4-bis(3-aminopropyl)piperazine and 4-aminomethylpiperidine; the aromatic 
polyamines such as benzene, toluene and xylene diamines and the methylene 
dianilines. Also included are a large variety of commercial polyamines 
based on fatty acid chemistry including dimer acid based products such as 
Versamine.RTM.551 and 552 (sold by Henkel Corporation) and 
Kemamine.RTM.DP-3680 and DD-3680 (sold by Humko Chemical Div., Witco 
Chemical Corp.). 
Amine groups can be introduced into a variety of backbone polymeric or 
oligomeric structures containing functional groups such as oxirane, 
isocyanate and carboxy, by reacting these materials under conditions, well 
known to the art with low molecular weight polyamines or amine 
intermediates. Amine groups can be attached to oligomers such as 
polyester, acrylic, and urethane oligomers having carboxy groups, by 
reacting the carboxy groups with difunctional amines. Also such free 
carboxy groups can be reacted with alkyleneimine or substituted 
alkyleneimine, as set forth in U.S. Pat. No. 3,679,564 and U.S. Pat. No. 
3,617,453. 
Blocked amines can be attached to backbone polymers and oligomers and 
subsequently transformed into primary amine groups. Such blocked amine 
groups can be attached to epoxy resins or acrylic resins having pendant 
oxirane groups by reacting a ketimine derived from reacting an excess of 
ketone with a polyamine containing at least one primary amine group and a 
secondary amine group. Blocked amines reacted with epoxy resins are 
described in U.S. Pat. No. 4,379,911. Blocked amines can also be reacted 
with carboxy containing compounds such as dimerized fatty acids as 
described in U.S. Pat. No. 3,523,925. 
Representative polyamine polymers containing amine groups can be derived 
from epoxy and epoxy-modified diglycidyl ethers of bisphenol A, various 
aliphatic polyethylene or polypropylene glycol (diglycidyl ether) adducts, 
and glycidyl ethers of phenolic resins, such epoxy resins being 
commercially available. The preparation of adducts of polyepoxide resins 
and polyamines is described in detail in U.S. Pat. Nos. 4,093,594 and 
4,111,900. Polyadducts of ammonia and epoxide compounds are described in 
U.S. Pat. No. 4,310,645. 
Polyamine polymers containing primary and secondary amine groups can be 
modified further by reacting them partially with monoepoxides, diepoxides 
or other amine reactive reagents. These reactions can be used to moderate 
the reactivity of the polyamine component with dihydrobenzoxazines. Also, 
such reactions can be used to plasticize, flexibilize and otherwise modify 
the properties of the cured compositions of the present invention. 
The polyamine component can also be modified by forming ketimine 
derivatives of the pendant primary amine groups or by forming organic acid 
salts of the pendant amines. When these modified polyamine components are 
combined with certain poly(dihydrobenzoxazine) components disclosed 
herein, they form more stable two component compositions. The systems are 
made curable by hydrolyzing the ketimine or by volatilizing the organic 
acid by application of heat. 
The polyamine component can also be in the form of oxazolidine functional 
polymer. In this case pendant secondary amine groups are blocked by the 
formation of oxazolidine derivatives. Mixtures of polybenzoxazines with 
oxazolidine blocked polyamines are stable until hydrolysis frees the 
reactive secondary amine functions which then become heat curable. Methods 
of preparing certain oxazolidinefunctional polymers are described in U.S. 
Pat. No. 4,373,008. 
Other useful polymers containing amine groups include polyamide resins, for 
example, condensation products of dimerized fatty acids coreacted with 
difunctional amine, such as ethylene diamine. Polyamide resins generally 
have a molecular weight between about 500 and 5,000. Further useful 
polymers containing amine groups include amine modified acrylic resins, 
polyester resins and polyurethane resins having a molecular weight range 
of about 500 to about 5,000. 
The relative proportions of polybenzoxazine and polyamine components to 
allow the compositions of the present invention to cure, may fall within a 
wide range depending upon the particular composition of each of the 
components. For maximum cure response at least one dihydrobenzoxazine 
group is present to react with each primary amine group present in the 
polyamine. However, additional dihydrobenzoxazine groups may be present to 
react with the secondary amine groups of the polyamine or with the 
secondary amine groups which form when a dihydrobenzoxazine reacts with a 
primary amine group. In general, the amount of dihydrobenzoxazine 
functionality used is sufficient to react with enough of the primary 
and/or secondary amine groups present in the polyamine to result in 
crosslinking at elevated temperature cure to whatever extent is desired or 
needed to obtain a satisfactory balance or combination of mechanical 
properties and chemical and solvent resistance in the cured composition. 
The ratio of poly(dihydrobenzoxazine) to polyamine advantageously may fall 
in the range of 0.2 to 3.0 equivalents of dihydrobenzoxazine group in the 
poly(dihydrobenzoxazine) per equivalent of actual and/or potential primary 
and/or secondary amine in the polyamine. 
The two component compositions of the present invention may be cured at a 
temperature in the range of about 50.degree. to about 200.degree. C. 
Preferably curing is effected in the temperature range of about 
100.degree. to about 160.degree. C. when the dihydrobenzoxazine component 
is derived from an aromatic amine and the amine component of the two 
component composition is a primary amine. When the benzoxazine component 
is derived from an aliphatic amine, the cure temperature is preferably in 
the range of about 130.degree. to about 180.degree. C. 
The two component compositions of the present invention can be catalyzed 
with selected catalysts to speed or accelerate the cure at a given 
temperature or to enhance the degree of cure at a lower temperature. The 
more effective catalysts are generally Lewis acids, metal salts or complex 
compounds (particularly chelates). Suitable Lewis acids include 
iron-II-chloride, iron-III-chloride, zinc chloride, tin-II-chloride, 
tin-IV-chloride, aluminum-chloride, zinc cyanide, borontrifluoride and 
borontrifluoride etherate. 
Suitable metal salts are salts of transition metals, if they do not come 
within the group of Lewis acids such as cobalt-, manganese- and 
lead-naphthenates; iron oleates; zinc, tin and organotin salts of C.sub.1 
-C.sub.20 carboxylic acids such as zinc and tin (II)-naphthenates, 
hexoates, octoates, palmitates, stearates and dimethylvalerates; 
dibutyltin diacetate, dibutyltin dioctoate, and dibutyltin dilaurate; and 
acetates, chlorides, sulphates and octoates of bi- and trivalent cobalt, 
of mono- and bivalent copper and bivalent lead. Suitable complex compounds 
include carbonyls of nickel, iron, molybdenum, cobalt, manganese and 
tungsten; acetyl acetonates of iron, copper, nickel, cobalt, zinc, lead, 
aluminum, manganese, magnesium, molybdenum, titanium, thorium, zirconium 
and vanadium; bis-(dibenzoylmethane)-copper; bis(ethylacetoacetate)-copper 
and -iron; co-ordination compounds of titanium, zirconium, hafnium, 
thorium and manganese with .beta.-diketones, .beta.-ketoesters and 
.beta.-hydroxyaldehydes; di(2-ethylhexyl)-tin oxide and dioctyl tin oxide. 
Catalysts which are particularly suitable are: zinc octoate, tin octoate, 
dibutyltin diacetate, dibutyltin dimaleate, dibutyltin dilaurate, cobalt 
triacetate, cobalt trioctoate, copper (II)-acetate, and zirconium octoate. 
The quantity of catalyst used is generally in the range of from 1 ppm to 
20% by weight preferably from 100 ppm to 5% by weight based on the total 
weight of the reactants. However, it may be practically advantageous to 
keep the concentration of the catalyst as low as possible. The optimum 
catalyst concentration depends on the nature of the starting material and 
on the activity of the particular catalyst and can be readily determined 
by techniques known to those in the art. Selection of an appropriate 
catalyst is frequently determined by its compatibility with the 
polymerizable composition. 
The two component compositions of this invention are used as potting, 
encapsulating, molding and laminating resins and as surface coatings. They 
are conveniently used as solutions in organic solvents for surface coating 
applications. The poly(dihydrobenzoxazines) are generally soluble in 
chlorinated hydrocarbons, aromatic hydrocarbons cyclic ethers and the 
glycol ether solvents. Ketones such as methyl ethyl ketone and methyl 
isobutyl ketone can also be used as solvents. Mixed solvents can be used 
with the poly(dihydrobenzoxazines) and often improve compatibility with 
various polyamine coreactants. Preferred solvents include 2-ethoxyethanol, 
and 2-butoxyethanol and mixtures of these glycol ether solvents with 
xylene and toluene. The polyamine components are generally soluble in the 
same solvents as the poly(dihydrobenzoxazine). The 
poly(dihydrobenzoxazine) and polyamine solutions can be mixed and stored 
as a one package system or mixed just prior to use depending upon the 
stability of the mixtures. As disclosed herein, dihydrobenzoxazines 
derived from weakly basic amines generally form more stable solutions with 
polyamines than do dihydrobenzoxazines derived from strongly basic amines. 
Improved storage stability with certain poly(dihydrobenzoxazines) is 
achieved by mixing them with a ketimine blocked polyamine. Hydrolysis of 
the ketimine at the time of application makes the two component coating 
system reactive. With certain poly(dihydrobenzoxazines) described herein 
it is possible to stabilize their solutions with polyamines by forming an 
organic acid salt with the amine groups in the polyamine. Volatile organic 
acids are preferred for forming salts with pendant amine groups and 
include formic acid, acetic acid, propionic acid, butyric acid, acrylic 
acid, methacrylic acid and cyclohexanoic acid. The organic acid is 
preferably an aliphatic monocarboxylic acid having up to 4 carbon atoms. 
The concentration of the two component coating systems in solution can vary 
widely depending on the application requirements, economics and handling 
ease. 
The coating composition can also contain pigments of the conventional type 
such as iron oxides, lead oxides, strontium chromate, carbon black, 
titanium dioxide, talc, barium sulfate, phthalocyanine blue and green, 
chromic green, zinc phosphates, lead silicate, silica, silicates and the 
like. 
Defoamers, tints, slip agents, thixotropes and levelling agents are common 
auxiliary components to most coatings and may be employed in the 
compositions of the present invention. 
The compositions of the present invention may be used for coating numerous 
substrates, such as metals, wood, glass, and plastics to produce thereon 
after curing at temperatures between 50.degree. and 200.degree. C., and 
preferably between 100.degree. and 175.degree. C., protective films which 
possess chemical resistance, corrosion resistance, durability, hardness, 
toughness, flexibility, and other mechanical properties. The compositions 
are particularly desirable as primer coatings for metal surfaces. They 
exhibit good adhesion to various substrates including galvanized metal, 
cold rolled steel (untreated and phosphate treated), hot rolled steel, and 
aluminum. The coating compositions of the present invention can be applied 
to a variety of solid substrates by conventional methods, such as flowing, 
spraying or dipping to form a continuous surface film.

The invention is further described and illustrated in the following 
examples which should not be construed as limiting its scope. All parts 
and percentages are by weight unless otherwise indicated. The percent 
closed dihydrobenzoxazine value represents the percentage of primary amine 
incorporated into dihydrobenzoxazine rings. The remainder is consumed in 
side reactions. 
EXAMPLE I 
Preparation of Dihydrobenzoxazine 1 
To a suitably equipped glass resin reactor equipped with stirrer is charged 
450 parts phenol, 450 parts toluene and 595 parts of 50% formalin. A 
uniform toluene-water dispersion is maintained with agitation. The 
temperature of the reaction mixture is adjusted to 25.degree. C. and 
maintained below 30.degree. C. while 144 parts of ethylene diamine are 
added slowly. The reaction mixture is stirred for 2 hours at 30.degree. C. 
after the amine addition is complete. The reaction mixture is heated to 
46.degree. C. under reduced pressure and refluxed for 3 hours. After 3 
hours the distillate is passed through an oil water separator in the 
distillate return line. The toluene is continuously returned to the 
reactor while the water is removed. Azeotropic water removal is continued 
while the batch temperature is increased to 69.degree. C. and the pressure 
is gradually reduced to about 5.0 kPa. The reaction mixture is essentially 
water free. It is cooled while 150 parts of 2-butoxyethanol are added and 
mixed in. The clear pale yellow solution is filtered. The product had the 
following composition and properties: Percent closed dihydrobenzoxazine 
66%; equivalent wt. 224; solids 55.2%; Brookfield viscosity 12 cps 
@25.degree. C. 
EXAMPLE II 
Alternate Method For Benzoxazine 1 
To a suitably equipped glass resin reactor equipped with stirrer is charged 
450 parts phenol, 450 parts methylene chloride and 144 parts of ethylene 
diamine. The temperature of the reaction mixture is adjusted to 25.degree. 
C. and 595 parts of 50% formalin is added while maintaining the 
temperature below 30.degree. C. The reaction mixture is stirred for 2 
hours at 30.degree. C. after formaldehyde addition is complete. The 
reaction mixture is heated to atmospheric reflux and refluxed for 3 hours. 
The reaction mixture is allowed to cool and separate into two layers. The 
upper water layer is withdrawn and discarded. The lower organic layer is 
reheated to atmospheric reflux and distilled to remove solvent. Heating is 
continued with the gradual application of vacuum until a temperature of 
70.degree. C. at about 5.0 kPa pressure is reached. The very viscous 
product is removed from the reactor and allowed to cool. The light yellow 
semi-solid product has 67% closed dihydrobenzoxazine ring. Upon standing, 
the clear amorphous product slowly crystallizes to an opaque, grainy 
solid. 
EXAMPLE III 
Preparation of Dihydrobenzoxazine 2 
The procedure of Example 1 is repeated except that 397.4 parts of 70% 
hexamethylene diamine are used in place of the ethylene diamine. The 
hexamethylene diamine (HMD) solution is added slowly with good agitation 
to prevent any buildup of polymeric HMD-formaldehyde condensate. The clear 
pale yellow solution of poly(dihydrobenzoxazine) has the following 
composition: Percent closed dihydrobenzoxazine 60%, equiv. wt. 330, solids 
59.0%. 
EXAMPLE IV 
Preparation of Dihydrobenzoxazine 3 
The procedure of Example III is repeated except that 719 parts of 
t-butylphenol is used in place of the 450 parts of phenol. The clear pale 
yellow solution of poly(dihydrobenzoxazine) has the following composition 
and properties. Percent closed dihydrobenzoxazine ring 69%, equiv. wt. 
336, solids 63.8%; Brookfield viscosity 110 cps. 
EXAMPLE V 
Preparation of Dihydrobenzoxazine 4 
To a suitably equipped glass resin reactor equipped with stirrer are 
charged 100 parts bisphenol A, 70 parts toluene and 81.5 parts of aniline. 
The slurry is warmed and agitated to form a uniform solution. An inert 
nitrogen atmosphere is maintained over the reaction mixture. The 
temperature of the reaction mixture is adjusted to 50.degree. C. and 108 
parts of 50% formalin are added slowly, while the temperature is 
maintained at 50.degree. to 55.degree. C. After formalin addition is 
complete the batch is refluxed at 65.degree. C. for 1 hour under reduced 
pressure. The batch is then heated to atmospheric reflux and the reflux 
condensate is permitted to separate into an aqueous phase and organic 
phase in an oil/water separator. The organic phase of the condensate is 
returned to the reactor and the aqueous phase is removed. After about 83 
parts of water are removed and the reaction temperature reaches 
116.degree. C., the clear product solution is cooled while 21 parts of 
2-butoxyethanol are added. The clear pale yellow solution of 
poly(dihydrobenzoxazine) had the following composition and properties: 
percent closed dihydrobenzoxazine ring 83%, equiv. wt. 278, solids 71.6%, 
Brookfield viscosity 305 cps. 
EXAMPLE VI 
Preparation of Dihydrobenzoxazine 5 
To a suitably equipped glass resin reactor equipped with stirrer are 
charged 228 parts of Bisphenol A, 240 parts toluene and 130.0 parts of 
monoethanolamine. The slurry is warmed and stirred to form a uniform 
solution. An inert nitrogen atmosphere is maintained over the reaction 
mixture. The temperature of the reaction mixture is adjusted to 50.degree. 
C. and 256 parts of 50% formalin are added slowly, while the temperature 
is maintained at 50.degree.-55.degree. C. After formalin addition is 
complete the batch is refluxed at 70.degree. C. for 3 hours under reduced 
pressure. The stirring is stopped and the reaction mixture is allowed to 
separate into two layers. The top water layer (175 parts) is removed. The 
remaining organic bottom layer is heated with the gradual application of 
vacuum to remove remaining solvent and other volatiles. When the 
temperature reaches 110.degree. C. at a pressure of 3.5 kPa, the fluid 
resin is poured from the reactor and allowed to solidify. The resulting 
yellow product has a dihydrobenzoxazine ring content of 63%, a calculated 
equivalent weight of 316, and a softening point of 88.degree. C. A 
solution of the resin dissolved in methyl ethyl ketone solvent is observed 
to gel after 1 month storage at room temperature. A sample in solid form 
shows no compositional change after 1 year at room temperature. 
EXAMPLE VII 
Preparation of Mixed Dihydrobenzoxazine 6 
To a suitably equipped glass resin reactor equipped with stirrer are 
charged 228 parts of Bisphenol A, 240 parts toluene, 93.1 parts of aniline 
and 65.2 parts of monoethanolamine. The slurry is warmed and stirred to 
form a uniform solution. An inert nitrogen atmosphere is maintained over 
the reaction mixture. The temperature of the reaction mixture is adjusted 
to 50.degree. C. and 256 parts of 50% formalin are added slowly, while the 
temperature is maintained at 45.degree.-50.degree. C. After formalin 
addition is complete the batch is refluxed at 60.degree. C. for 3 hours 
under reduced pressure. The stirring is stopped and the reaction mixture 
is allowed to separate into two layers. The top water layer (167 parts) is 
removed. The remaining organic bottom layer is heated with the gradual 
application of vacuum to remove the remaining solvent and other volatiles. 
When the temperature reaches 110.degree. C. at a pressure of 3.5 kPa, the 
fluid resin is poured from the reactor and allowed to solidify. The 
resulting yellow product has a dihydrobenzoxazine ring content of 69%, a 
calculated equivalent weight of 312, and a softening point of 78.degree. 
C. 
EXAMPLE VIII 
Preparation of Polyamine A 
Eight hundred and seventy five parts of polyglycidyl ether of Bisphenol A 
(sold by Shell Chemical Co. under the tradename Epon 1004F) possessing an 
epoxy equivalent weight of 875 is added to 516 parts of methyl isobutyl 
ketone and the mixture is stirred and heated to 60.degree. C. to dissolve 
the epoxy resin while any water present is removed by azeotropic 
distillation under reduced pressure. At 60.degree. C. under a dry nitrogen 
blanket, 414 parts of a methyl isobutyl ketone solution containing 267.4 
parts of diketimine derived from one mole of diethylene triamine and 2 
moles of methyl isobutyl ketone (as described in U.S. Pat. No. 3,523,925) 
are added and the batch is heated to 120.degree. C. where it is held for 2 
hours. The batch is cooled to 80.degree. C. and 36 parts of water are 
added and mixed in to hydrolyze the ketimine. The pale yellow polyamine 
solution is cooled and filtered. The product has a calculated number 
average m.w. of 1956 and is essentially tetrafunctional in primary amine. 
The solids content of the product solution is 54.8%. 
EXAMPLE IX 
Preparation of Polyamine B 
The procedure of Example VIII is repeated except that at 60.degree. C. 
under a dry nitrogen blanket, 170.3 parts of a monoketimine derived from 1 
mole of N-methyl-1,3-propane diamine and 1 mole of methyl isobutyl ketone 
are added in place of the diketimine and the batch is heated to 
120.degree. C. where it is held for 2 hours. The batch is cooled to 
80.degree. C. and 18 parts of water are added and mixed in to hydrolyze 
the ketimine. The dark yellow polyamine solution is cooled and filtered. 
The product has a calculated number average molecular weight of 1926 and 
is essentially difunctional in primary amine. The solids content of the 
solution is 68.2%. 
EXAMPLE X 
Preparation of Polyamine C 
The procedure of Example VIII is repeated and after the addition of 36 
parts of water, the reaction is cooled to 60.degree. C. At 60.degree. C., 
229 parts of an aliphatic mono glycidyl ether (sold by Ciba Geigy under 
the tradename Araldite DY027) possessing an epoxy equivalent weight of 229 
is added. The reaction mixture is held at 60.degree. C. for 1 hour and 
then cooled and filtered. The product had a calculated number average 
molecular weight of 2414 and is essentially difunctional in primary amine 
and difunctional in secondary amine. The solids content is 64.4%. 
EXAMPLE XI 
Preparation of Polyamine D 
The procedure of Example X is repeated except that in place of the Araldite 
DY027, 280 parts of a butyl glycidyl ether (sold by Ciba Geigy under the 
tradename Araldite RD-1) possessing an epoxy equivalent weight of 140 are 
added. After adding the monoepoxide at 60.degree. C. and holding one hour 
the reaction mixture is heated to 120.degree. C. for 2 hours. The solution 
is cooled and filtered. The product has a calculated average molecular 
weight of 2516 and is essentially tetrafunctional in secondary amine with 
a low residual primary amine content. The solids content is 62.0%. 
Table II summarizes the properties of Examples VIII to XI made to have 
different reactive functionality arising from different levels of primary 
and secondary amine content. 
TABLE II 
__________________________________________________________________________ 
POLYAMINE COMPONENTS - EPOXY BACKBONE 
##STR3## 
where: 
##STR4## 
Average 
Approximate Reactive 
Example 
Polyamine M.W. Amine Functionality and 
__________________________________________________________________________ 
Type 
VIII A. 
##STR5## 1956 Tetrafunctional 1.degree. Amine 
IX B. 
##STR6## 1926 Difunctional 1.degree. Amine 
X C. 
##STR7## 75% R.sub.3 = H 25% R.sub.3 = Adduct of 
monoepoxide Araldite EY027 
2414 Difunctional 1.degree. Amine 
Difunctional 2.degree. Amine 
XI D. 
##STR8## 50% R.sub.3 = H 50% R.sub.3 = Adduct of 
monoepoxide Araldite RD-1 
2516 Tetrafunctional in 2.degree. 
Amine 
__________________________________________________________________________ 
EXAMPLE XII 
Dihydrobenzoxazine Compositions 
Eight coating compositions made from combinations of the four polyamines of 
Examples VIII to XI with different dihydrobenzoxazines are shown in Table 
III. Test results on coated metal test panels obtained under different 
cure conditions are included in the table. The coatings are normally draw 
coated at 50% solids solution on zinc phosphated test panels to give dry 
coatings of 28.+-.5 microns in thickness. The results generally illustrate 
the excellent coating properties which can be obtained from the two 
component systems claimed in this invention when properly cured. 
A comparison of Example XII-2 involving a dihydrobenzoxazine derived from a 
weak base amine (aniline) with Examples XII-3 and XII-4 involving 
dihydrobenzoxazines derived from stronger base amines was made using 
polyamine C formulated at constant equivalents of added 
dihydrobenzoxazine. Example XII-2 develops a combination of coating 
hardness, solvent resistance and corrosion resistance at cure temperatures 
14.degree. to 28.degree. C. lower in temperature than Examples XII-3 and 4 
containing dihydrobenzoxazines derived from strong base amines. 
Further, dihydrobenzoxazine 4 derived from a weak base amine when used in 
Example XII-6, with high secondary amine containing polyamine D, also 
develops cure properties at temperatures at least 30.degree. C. lower than 
Examples XII-7 and 8 based on the stronger base dihydrobenzoxazines 
combined with polyamine D. 
The effect of using catalysis is also demonstrated by the data in Table 
III. Dihydrobenzoxazine 4 was combined with a low functionality polyamine 
B in Example XII-5. The cured film developed reasonable properties at 
177.degree. C. cure. However, with 1.5 to 2.0% levels of tin octoate 
catalyst excellent film properties were obtained at 149.degree. C. 
TABLE III 
__________________________________________________________________________ 
COATING COMPOSITIONS COMPRISING DIHYDROBENZOXAZINE AND POLYAMINE 
Equiva-.sup.a 
lents 
Bake.sup.b Gardner.sup.d 
Dihydro- Weight 
DHB per 
Temp. 
MEK.sup.c 
Pencil 
Impact 
Salt Spray.sup.e 
Example 
benzoxazine 
Polyamine 
Ratio 
mole PA 
.degree.C. 
rubs Hardness 
(Joules) 
500 hr. 
__________________________________________________________________________ 
XII (1) 
4 A 36:64 
4 149 &gt;200 4H 2.26/2.83 
.02 
XII (2) 
4 C 26:74 
3 121 200(37%) 
2H 2.26/2.83 
.02 
135 200(5%) 
2H 2.83/3.39 
.02 
149 &gt;200 4H 3.39/3.96 
.02 
177 &gt;200 5H 3.39/3.96 
.02 
XII (3) 
1 C 22:78 
3 135 70 F 1.13/1.70 
.02 
149 200(75%) 
4H 1.13/1.70 
.02 
177 &gt;200 4H 3.39/3.96 
.02 
XII (4) 
2 C 29:71 
3 135 200(5%) 
H 2.26/2.83 
.15 
149 200(5%) 
2H 2.26/2.83 
.07 
177 &gt;200 4H 3.39/3.96 
.03 
XII (5) 
4 B 30:70 
3 149 200(60%) 
3H 2.26/2.83 
.03 
177 &gt;200 5H 2.83/3.39 
.03 
149.sup.f 
200(5%) 
4H 2.26/2.83 
.03 
149.sup.g 
&gt;200 5H 2.26/2.83 
.03 
XII (6) 
4 D 24:76 
3 135 140 F 1.70/2.26 
.09 
163 &gt;200 4H 3.39/3.96 
.03 
177 &gt;200 5H 3.96/4.52 
.07 
XII (7) 
1 D 20:80 
3 163 165 2H 1.70/2.26 
.02 
193 &gt;200 4H 1.70/2.26 
.02 
XII (8) 
2 D 27:73 
3 163 200(12%) 
3H 1.70/2.26 
.03 
193 &gt;200 4H 1.70/2.26 
.02 
__________________________________________________________________________ 
.sup.a Number of equivalents of dihydrobenzoxazine based on active ring 
content for each average molecular weight unit of polyamine as indicated 
in Table II. 
.sup.b All panels are baked for 20 minutes at indicated bake temperature 
in .degree.C. 
.sup.c MEK double rubs. Value in parenthesis indicates estimated amount o 
film removed after 200 rubs. 
.sup.d Standard Gardner Impact test, forwardjoules. Values represent 
pass/fail. 
.sup.e Standard salt spray test ASTM B 117. Values are maximum scribe 
creep in inches after 500 hours. 
.sup.f 1.5% stannous octoate catalyst. 
.sup.g 2.0% stannous octoate catalyst. 
EXAMPLE XIII 
Dihydrobenzoxazine Compositions 
Sixteen coating compositions made from combinations of eight low molecular 
weight polyamines with different dihydrobenzoxazines are shown in Table 
IV. Test results on coated metal test panels obtained under different cure 
conditions are included in the table. The coatings are normally draw 
coated at 50% solids solution on zinc phosphated test panels to give dry 
coatings of 28.+-.5 microns in thickness. The results generally illustrate 
the excellent coating properties which can be obtained from the two 
component systems claimed in this invention when properly cured. 
It is obvious from a comparison of the examples in the table that the 
nature of the polyamine can contribute significantly to the performance of 
the cured coating compositions. Certain polyamine dihydrobenzoxazine 
combinations such as Example XIII-16 where a polyoxypropylene backbone 
amine is used do not give as good salt spray corrosion results as 
compositions based on polymethylene based polyamines such as 
triaminononane shown in Examples XIII 4-9 or hexamethylene diamine in 
Example XIII-14. Compositions utilizing polyamines derived from dimer acid 
backbones result in cured coatings with higher flexibility as demonstrated 
by impact values in Examples XIII 10-12 and XIII 15. 
The ultimate coating properties of a given composition are dependent on 
cure temperature and time. Examples XIII 4-6 show the property changes 
with a constant composition based on triaminononane and dihydrobenzoxazine 
4 cured at three temperatures. As a general rule, compositions that give 
longer dry rubber cure times as illustrated in Table IV require higher 
temperatures or longer cure times to reach certain optimum coating 
properties such as solvent resistance. The Dry Rubber Cure data in Table 
IV also illustrate the better cure response of compositions utilizing 
dihydrobenzoxazine 4 derived from a weak base amine compared with 
dihydrobenzoxazines 2 and 3 derived from a strong base amine. 
The Examples in Table IV illustrate the many possible polyamine structures 
that can be used in combination with dihydrobenzoxazines in practicing 
this invention. Many combinations of one or more polyamines with one or 
more dihydrobenzoxazines are possible and may be advantageously used to 
gain certain coating property or performance characteristics. 
TABLE IV 
__________________________________________________________________________ 
COATING COMPOSITIONS COMPRISING DIHYDROBENZOXAZINE AND LOW M.W. 
POLYAMINE 
Equiva-.sup.a 
lents DHB 
D.R. 
Dihydro- per primary 
Cure Bake.sup.b 
Pencil 
Gardner.sup.d 
benzox- Weight 
amine equi- 
@ 135.degree. C. 
Temp. 
MEK.sup.c 
Hard- 
Impact 
Salt Spray.sup.e 
Example 
azine 
Polyamine Ratio 
valents 
(sec.) 
.degree.C. 
Rubs 
ness Joules 
500 hr., 
__________________________________________________________________________ 
mm. 
XIII 1 
4 Diethylene triamine 
1/.14 
1.33 211 149 &gt;200 
4H 1.13/1.70 
1.27 
2 2 " 1/.13 
1.33 260 149 &gt;200 
6H 1.70/2.26 
0.25 
3 3 " 1/.11 
1.33 &gt;600 149 125 
2H 0/0.57 
0.25 
4 4 Triaminononane 
1/.19 
1.00 103 121 200 
5H 0.57/1.13 
0.76 
(15%) 
5 4 " 1/.19 
1.00 103 135 &gt;200 
6H 2.83/3.39 
0.25 
6 4 " 1/.19 
1.00 103 149 &gt;200 
7H 3.39/3.96 
0.25 
7 4 " 1/.14 
1.33 134 149 &gt;200 
7H 2.26/2.83 
0.25 
8 2 " 1/.14 
1.33 134 149 &gt;200 
6H 2.26/2.83 
0.25 
9 3 " 1/.12 
1.33 &gt;600 149 &gt;200 
8H 3.39/3.96 
0.25 
10 4 Versamine 552 
1/.71 
1.33 230 149 &gt;200 
2H 13.6/14.7 
1.78 
11 3 " 1/.61 
1.33 &gt;600 177 &gt;200 
F &gt;18 0.25 
12 4 Kenamine 1/.71 
2.00 458 149 &gt;200 
F &gt;18 1.78 
003680 
13 4 Methylene 1/.54 
1.33 362 149 &gt;200 
5H 4.52/5.09 
1.02 
Dianiline 
14 4 Hexamethyl- 
1/.16 
1.33 214 149 &gt;200 
5H 1.70/2.26 
0.76 
ene diamine 
15 4 Versamine 1/0.48 
2.00 388 149 &gt;200 
2H 6.22/6.78 
1.27 
551 
16 4 Jeffamine 1/0.42 
1.33 339 149 &gt;200 
7H 3.39/3.96 
0.51 
T403 
__________________________________________________________________________ 
.sup.a Number of equivalents of dihydrobenzoxazine based on active ring 
content for each equivalent of primary amine in the polyamine. 
.sup.b All panels are baked for 20 minutes at indicated bake temperature 
in .degree.C. 
.sup.c MEK double rubs. Value in parenthesis indicates estimated amount o 
film removed after 200 rubs. 
.sup.d Standard Gardner Impact test, forwardjoules. Values represent 
pass/fail. 
.sup.e Standard salt spray test ASTM B 117. Values are maximum scribe 
creep in inches after 500 hours. 
EXAMPLE XIV 
Ketimine Formation From Versamine 552 
To a suitably equipped glass resin reactor equipped with a stirrer is 
charged 274 parts of Versamine 552 (primary amine equivalent wt.=274) and 
280 parts of methyl isobutyl ketone (MIBK). The reaction is kept under an 
inert nitrogen atmosphere and heated to atmospheric reflux. The distillate 
is passed through an oil/water separator and the water is removed and MIBK 
is returned to the reactor. Heating and water removal is continued until 
water evolution ceases (.about.18 parts water). The solution is cooled and 
stored under dry nitrogen. The light yellow solution contains 67.0% of the 
MIBK ketimine of Versamine 552. 
EXAMPLE XV 
Stabilized Compositions 
The stabilization of a solution containing polyamine and dihydrobenzoxazine 
is illustrated with the formulations in Table V in which the polyamine is 
deactivated by formation of an acid salt or a ketimine. Dihydrobenzoxazine 
4 (Example V) is combined with Versamine 552 polyamine at a DHB/amine 
equivalence ratio of 1.33/1.0. In Example XV A, the amine and 
dihydrobenzoxazine are dissolved in a mixed butyl cellosolve MIBK solvent. 
In Example XV B, one equivalent of formic acid for each equivalent of 
primary amine is added to the formulation. In Example XV C, Versamine 552 
diketimine, as prepared in Example XIV, is substituted for the unmodified 
Versamine 552 on an equimolar basis in a dry MIBK solution. 
The solutions are allowed to age at 25.degree. C. and viscosity, dry rubber 
and visual changes with time are followed. The results are summarized in 
Tables VI and VII. 
When the components of Example XV are mixed to form Example XVA, an 
immediate viscosity increase is caused by the formation of association 
complexes of the dihydrobenzoxazine and polyamine molecules in the 
composition. This viscosity rapidly increases with a corresponding 
decrease in the D.R. cure time Tables VI and VII. The precipitation of 
insoluble material is observed after fourteen days and this continues with 
time. The viscosity data of Table VI show the rapid increase in viscosity 
for XV A. Viscosity was not recorded after 14 days because of the large 
amount of product precipitation which started to occur. These effects are 
primarily caused by substantial coreaction of dihydrobenzoxazine and 
polyamine. 
When the components of Example XV B are mixed after first forming the 
formic acid salt of the Versamine 552, an immediate high solution 
viscosity develops. This is apparently due to the very strong molecular 
association of the protonated cationic amine groups imparting 
polyelectrolyte behavior. However, the subsequent rate of change of 
viscosity with aging is much less than in the case of Example XV A. The 
dry rubber cure shortens at a much slower rate than in the case of the 
nonacidified composition. The solution remains clear without any precipate 
or insolubles forming. This indicates the acidified compositions are more 
stable and do not advance appreciably in molecular weight. 
When Example XV C is mixed using the ketimine blocked Versamine 552, a very 
low viscosity solution is obtained. The ketimine blocked polyamine will 
not function as readily in forming association complexes as in the case of 
Examples XV A and B. The dry rubber cure stays above the 600 sec. level. 
Advancement of the composition appears minimal although the viscosity does 
increase over the 70 day test period. No insolubles form in this 
composition. 
Both the acid and ketimine methods can be used to stabilize the 
compositions of this invention and inhibit advancement of molecular weight 
arising from chemical reaction of the dihydrobenzoxazine with polyamine. 
The ketimine formation route is more effective in controlling solution 
viscosity buildup. However when compositions XV B and XV C are coated onto 
a metal substrate and heated under curing conditions, the acid is 
volatilized from composition XV B and the MIBK ketimine is hydrolyzed and 
MIBK volatilized from composition XV C, generating the free polyamine 
which then reacts with the polydihydrobenzoxazine. 
TABLE V 
______________________________________ 
COMPOSITIONS OF EXAMPLES 
XV A, B, AND C 
(Parts by weight) 
Dihydro- 
benzo- 
Ver- xazine 
Com- sa- Versamine.sup.a 
4 Butyl 90% 
po- mine 552 Ketimine 
100% Cello- Formic 
sition 
552 100% Solids 
Solids solve MIBK Acid 
______________________________________ 
XV A 30.3 0 41.2 17.6 10.9 0 
XV B 30.3 0 41.2 11.9 10.9 5.7 
XV C 0 39.4.sup.a 41.2 0 19.4 0 
______________________________________ 
.sup.a Reaction product from Example XIII, 39.4 parts ketimine solids 
equivalent to 30.3 parts of Versamine 552. 
TABLE VI 
______________________________________ 
AGING EFFECTS OF EXAMPLES XV A, B AND C 
Brookfield Viscosity, Pa sec 
Days at 25.degree. C. 
XV A XV B XV C 
______________________________________ 
0 1.2 11.5 0.25 
15 75.0 65.0 0.45 
30 heavy precipi- 95.0 0.70 
tate after 21 
days 
48 -- 110 0.95 
64 -- 115 1.05 
______________________________________ 
TABLE VII 
______________________________________ 
AGING EFFECTS OF EXAMPLES XV A, B AND C 
Dry Rubber cure values 
Days @ @ 135.degree. C., seconds.sup.a 
25.degree. C. 
XV A XV B XV C 
______________________________________ 
0 315 (0%) 278 (0%) 600 
15 99 (31%).sup.b 
189 (68%) 600 
30 65 (21%).sup.b 
185 (67%) 600 
48 44 (14%).sup.b 
185 (67%) 600 
64 40 (13%).sup.b 
187 (67%) 600 
______________________________________ 
.sup.a Value in parenthesis is % of original D.R. cure 
.sup.b Insolubles started forming after 15 days in XV A and dry rubber wa 
measured only on soluble portion. XV B and XV C remained clear and 
homogeneous. 
DRY RUBBER CURE TEST 
The Dry Rubber Cure Test (D.R. Cure) is used as a basis of comparison of 
the relative time to gelation of various dihydrobenzoxazine/polyamine 
compositions. The test is also used to follow aging (advancement) of these 
compositions with time. The test involves placing 4 to 5 drops of the 
composition being tested on the center of a flat cure plate controlled at 
135.degree. C. A flat 12.2 mm stainless steel spatula is used to spread 
and butter the compositions over a 25.4 mm diameter area. The time in 
seconds is recorded from the initial placement on the hot plate until the 
composition ceases the flow (string) when buttered with the spatula and 
becomes a rubbery film no longer movable with the spatula. 
CARBON-13 NUCLEAR MAGNETIC RESONANCE SPECTROMETRY OF DIHYDROBENZOXAZINE 
STRUCTURE 
Carbon spectra are recorded with a JEOL FX90Q spectrometer at room 
temperature. Dihydrobenzoxazines are preferably dissolved in chloroform or 
carbon tetrachloride solvents. Typically solution concentrations in the 
30-50% solids range are run. The JEOL FX90Q is equipped with an external 
Li lock. Quantitative NNE measurement conditions are as follows: 
Field=22.5 MH.sub.z, sample tube Q=10 mm, sweep width=5000 H.sub.z, pulse 
width=20 microseconds, accumulation=2K, acquisition time=0.819 sec., pulse 
delay=30 seconds. 
Chemicals shifts were related to TMS (0 ppm) and expressed in ppm. 
Assignments were based on known literature references and values measured 
on model compounds by methods well known to those skilled in the art. The 
dihydrobenzoxazine carbons are numbered conventionally. 
##STR9## 
By comparing the carbon at ring position number 9, in a closed ring 
(.about.150-154 ppm) relative to the same carbon with the benzoxazine ring 
open and a --OH group attached (.about.154-157 ppm) a direct measure of % 
closed ring benzoxazine is obtained. Measurement of the carbon at ring 
position number 2, at 7.9 ppm when R' is a benzenoid ring or at 8.2 ppm 
when R' is a typical alkyl substituent also provides a direct measure of 
closed benzoxazine ring content. The quantitative relation of these 
carbons to the rest of the dihydrobenzoxazine carbons can be used to 
calculate both a % dihydrobenzoxazine content and an effective equivalent 
weight based on ring content. As those skilled in the art can readily 
appreciate, the nature of the substituent R and R' and the nature of 
various side reaction products result in other chemical shifts in the NMR 
spectra. The assignment of these shifts depends on the structure of the 
particular benzoxazine and can be used to measure many other structural 
features of a particular dihydrobenzoxazine.