12
Copolymers, Polyblends, and Composites Downloaded from pubs.acs.org by UNIV OF CALIFORNIA SANTA BARBARA on 09/22/18. For personal use only.
Aminimides XVI. Copolymerization Studies of Aminimides with 4-Vinylpyridine and N -Vinylpyrrolidone and Use of Copolymers in Adhesive Systems H. J. LANGER and B. M. CULBERTSON Research Center, A s h l a n d O i l , Inc., Columbus, Ohio 43216
Copolymerization studies demonstrated that aminimide, 1,1dimethyl-1-(2-hydroxypropyl)amine methacrylimide (DHA) co polymerizes readily with 4-vinylpyridine (4VP) and N-vinylpyr rolidone (NVP). These copolymers could be thermolyzed in solution to give soluble poly(4-vinylpyridine-co-isopropenyl iso cyanate) and poly(N-vinylpyrrolidone-co-isopropenyl isocyanate) materials. The reactivity ratios of each monomer pair were determined, and the Alfrey-Price Q and e values for DHA were calculated: for DHA (M )-4VP (M ), r = 0.41, r = 0.77, Q = 0.68, and e = 0.58; and for DHA (M )-NVP (M ), r = 0.15, r = 0.35, Q = 0.14, and e = 0.58. The DHA-4VP copolymers quaternized readily to give a new family of water-soluble poly electrolyte materials. The various copolymers were examined as adhesion promoters for rubber-tire cord composites. 1
2
1
2
1
2
1
2
I
t has been demonstrated that aminimide monomers, such as 1,1-dimethyll - ( 2 - h y d r o x y p r o p y l ) a m i n e methacrylimide ( D H A ) , are very useful for -
+
preparing reactive polymers with pendent acyl aminimide ( — C O N — N = ) residues ( I ) . Further, when the materials are heated, the aminimide group on these polymers suffers a carbon-nitrogen migration reaction, giving tertiary amines and reactive polymers w i t h pendent isocyanate moieties ( 1 ). B o t h the aminimide and isocyanate groups promote adhesion of polymers to various surfaces ( I ). The literature offers numerous examples of investigations of copolymers of vinylpyridines and N-vinylpyrrolidones and of their use i n adhesive applica tions. F o r example, 4-vinylpyridine ( 4 V P ) has been grafted onto rubber and used i n copolymers blended with rubber to improve the adhesion of rubbers to metals and other tire cord materials (2, 3, 4). P o l y ( N - v i n y l p y r r o l i d o n e ) has very good adhesion to glass, metals, and various plastics and can be used to give improved adhesion between glass fiber and other plastics i n glass fiber129
130
COPOLYMERS,
POLYBLENDS, A N D COMPOSITES
reinforced composites ( 5 ) . Copolymers of N-vinylpyrrolidone ( N V P ) and v i n y l acetate or acrylic esters are also useful as laminating and pressure-sensitive adhesives (6, 7 ) . This study was undertaken to see if improved tire cord adhesive systems could be developed using poly ( D H A - C O - 4 V P ) and/or poly ( D H A - c o - N V P ) materials. Since these copolymer systems were new and since previously published Q and e values for D H A ( 8 ) , 4 V P ( 9 ) , and N V P (10) suggested poor copolymerizability between the monomer sets, a detailed copolymeriza tion study of these monomer pairs was needed. In summary, this study was initiated to determine copolymerization characteristics, i.e. reactivity ratios, of D H A - c o - 4 V P and D H A - c o - N V P , to characterize briefly some of the physical and chemical properties of the resultant materials, and to evaluate select copolymers in tire cord adhesive systems. Experimental Monomers, Initiator, and Solvents. D H A was recrystallized from ethyl acetate (mp 1 4 6 ° - 1 4 7 ° C ) . 4 V P was dried over molecular sieves and frac tionally distilled under nitrogen; a middle fraction w i t h bp 64°C/18mm and n = 1.5551 was collected just prior to use. N V P was also dried and redis tilled under nitrogen just before use (bp 9 0 ° C / 1 0 m m ) . Monomers, hydroxyethyl acrylate ( H A ) , hydroxyethyl methacrylate ( H E M A ) , hydroxypropyl methacrylate ( H P M A ) , and glycidyl methacrylate ( G M A ) were used as re ceived from commercial sources. Azobis(isobutyronitrile) ( A I B N ) was recrys tallized from methanol (mp 1 0 2 ° - 1 0 3 ° C ) . The solvents N , N - d i m e t h y l f o r m amide ( D M F ) and cyclohexanone and the reagents methyl chloride and methyl chloroacetate were purified by standard techniques. A l l other solvents ( A R grade) were used as received. A n a l y t i c a l Procedures. T h e purity of all copolymers, i.e. absence of monomers, was checked by thin layer chromatography ( T L C ) . Composition of the D H A - c o - 4 V P copolymers was determined from elemental analysis data obtained by Micro-Analysis, Inc., W i l m i n g t o n , D e l . Compositions of the D H A - c o - N V P copolymers were determined by non-aqueous titration, using 0 . 1 N perchloric acid and gentian violet indicator in glacial acetic acid (11). Isocyanate was determined as reported previously (12). T h e nuclear magnetic resonance ( N M R ) spectra were recorded on a Varian A-60 spectrometer, using deuterated dimethyl sulfoxide ( D M S O ) as solvent and tetramethylsilane as internal standard. IR spectra were obtained on a Perkin-Elmer 237B IR spectrophotometer. A D u P o n t 900 differential thermal analyzer and a 950 thermal gravimetric analyzer unit were used for differential thermal analysis ( D T A ) and thermal gravimetric analysis ( T G A ) . A l u m i n a was used as reference, and the finely divided polymer samples were analyzed under nitrogen ( 0 ° - 5 0 0 ° C ) at heating rates of 10° or 20°C/min. G e l permeation chromatography ( G P C ) was run on a Waters model 200 G P C unit, using D M F as solvent. Inherent viscosities (r/ ) were determined in methanol at 3 0 ° C using Ubbelohde capillary viscometers (concentration, 0.5 g / d l ) . Copolymerization Studies. A l l copolymerizations for determining reac tivity ratios were CÎ Tied out under nitrogen in sealed Wheaton pressure bottles fitted w i t h a magnetic stir bar. The monomers, solvent (2-propanol, 4 0 % of total monomer), and A I B N were combined; the mixtures were then degassed by conventional freeze-thaw techniques, flushed under nitrogen, sealed, and polymerized (see Tables III and I V for conditions). A l l copolymerizations were terminated by pouring the reaction mixtures into a large excess of non-solvent (acetone or diethyl ether). The crude polymer was redissolved, reprecipitated D
2 5
inh
12.
LANGER
A N D CULBERTSON
Aminimides
131
by a non-solvent, collected, washed, dried to constant weight in vacuo, weighed to determine conversion, and checked for purity by T L C . Copolymerizations to high conversions were carried out in round-bottomed flasks fitted with stirrer, thermometer, gas inlet tube, and reflux condenser. A l l systems were deaerated, and the polymerizations were performed under nitro gen. Conversions were determined by weighing the isolated copolymers. The polymers were purified as described above. Rearrangement Reaction. The copolymers were dissolved in freshly dis tilled D M F or cyclohexanone (ca. 10% solids) and heated under reflux while a dry nitrogen stream was passed through the solution. After 1.5 hrs of reac tion, only a trace amount of amine was detectable in the distillate. The solution was allowed to cool, and the isopropenyl isocyanate copolymers were then isolated by pouring the thermolyzed polymer solution into a large excess of non-solvent. The polymers were filtered, washed, redissolved in chloroform, and then analyzed. Quaternization Reaction. In a pressure bottle equipped with a magnetic stirrer, the copolymer was dissolved in methanol, and methyl chloride was then added to slight excess. For reaction conditions, see Table V I . After the specified reaction time, the excess methyl chloride was allowed to evaporate, and the polymer was isolated by precipitation into acetone. After purification, the quaternized copolymer was characterized by IR and chlorine elemental analysis. Similar experiments were conducted using equimolar amounts of methyl chloroacetate. Adhesion Tests. The wire used for testing was National Standard single strand, brass-plated wire (diameter, 0.16"). T w o polyester cord materials were used, D u P o n t T-68-1300/3 and Fiber Industries T-785-1000/3. The general procedure for coating the steel wire consisted of cleaning the wire, coating it with the D H A - 4 V P copolymer, curing the coating 80 sec at 445 °F, coating the wire a second time with an emulsion consisting of a resorcinol-formaldehyde ( R F ) resin and a styrene-butadiene-vinylpyridine latex (Gen-Tac F S , General Tire & Rubber C o . ) , and curing the second coating 80 sec at 4 4 5 ° F . F o r polyester cord, the procedure was modified so that each coating process gave correct pretensioning and stretch to the finished cord. The first dip consisted of quaternized D H A - 4 V P or poly ( D H A - N V P ) copolymer and a commercial epoxide resin, and it was cured 45 sec at 4 4 5 ° F . In accordance with A S T M wire adhesion test D2229-635, the steel cord samples were embedded in a general purpose rubber stock, and the composite was vulcanized, aged, and then tested on an Instron tester at a head speed of 6 in./min. Eight samples per treatment were generally tested. Since the em bedment length was 0.25 i n . , the static adhesion, i.e. the force required to extract the steel cord, is reported in pounds per 0.25 inch. The polyester cord Η-pull tests were conducted according to A S T M D2138-67 procedure. Usually 18 samples were tested, and adhesion was reported as the number of pounds needed to p u l l a ^ - i n . length of cord from the vulcanized rubber. Results and Discussion General Copolymerization Studies. D H A - 4 V P S Y S T E M . In order to examine the copolymerizability of D H A with 4 V P and to investigate some properties of the copolymer, equimolar amounts of D H A and 4 V P were copolymerized i n 2-propanol at 7 0 ° C . The powdery, off-white, purified polymer was soluble i n D M F , slightly soluble in chloroform, and insoluble i n water and tetrahydrofuran ( T H F ) . In contrast, p o l y ( 4 V P ) was soluble in T H F , D M F , and chloroform. Extraction of the copolymer failed to produce D H A or 4 V P homopolymer. The G P C curve, with narrow molecular weight distribution and with only
132
COPOLYMERS,
POLYBLENDS,
AND
COMPOSITES
moderate amounts of molecular weight tails, demonstrated clearly that the copolymer was homogeneous. Attempts were made to determine structure by both N M R and IR. The IR spectrum of the copolymer(s) (free film) had absorption bands at 1605 and 755 c m " (pyridine ring vibrations), 825 c m " ( C - H deformation vibra tion), and 1580 c m " (aminimide carbonyl); this supported the structure of p o l y ( D H A - c o - 4 V P ) . The N M R spectrum showed D H A and 4 V P moieties, but the resolution was too poor for quantitative assignments. Thermal properties of the copolymer were investigated by D T A , T G A , and IR. The copolymer(s) had distinct thermograms, indicating transforma tion of the aminimide monomer segments to isopropenyl isocyanate residues and elimination of the tertiary amine, l , l - d i m e t h y l - l - ( 2 - h y d r o x y p r o p y l ) a m i n e . A typical D T A curve had a strong exotherm at 1 5 0 ° - 2 2 5 ° C (midpoint ca. 1 8 0 ° C ) ; the T G A curve indicated onset of weight loss at 150°C w i t h an increase to a maximum rate i n the region of the D T A exotherm. The weight loss of tertiary amine failed to match theoretical amounts because some amine was retained by the isocyanate-hydroxyl (urethane formation) reaction. W h e n copolymer films were heated at 1 5 0 ° - 2 0 0 ° C ) for various times, the band i n the spectra at 1580 c m " vanished and new bands appeared at 2260 c m " ( — N C O ) and 1710 c m " (urethane carbonyl). Mixtures with various D H A - 4 V P compositions were copolymerized to study the effect of monomer composition upon copolymer conversion. The 1
1
1
1
1
1
100
0
L. 0.0
1
1
0.2
I
I
0.4
I
I
0.6
I
I
1
0.8
.
1.0
DHA IN MONOMER FEED (MOLE FRACTION)
Figure 1.
Conversion and inherent viscosity as a function of monomer composition in the copolymerization of DHA with 4VP Conditions: 70°C,
3 hrs, and AIBN 2 wt % of total monomer
12.
LANGER
AND CULBERTSON
Aminimides
TIME
Figure 2.
133
(min)
Conversion vs. time plots of the copolymerization of DHA with 4VP
Conditions: 70°C, AIBN 2 wt % of total monomer, and monomer concentrations: upper curve, 40 mole % DHA and lower curve, 60 mole % DHA
polymer yield increased until the content of D H A i n the monomer mixture reached about 40 mole % ; it then decreased when this concentration was exceeded (see Figure 1 ) . Furthermore, the initial monomer feed had a strong effect on the inherent viscosity; increasing the D H A content i n the feed lowered the molecular weight of the isolated polymer, probably b y increased chain transfer reactions. T y p i c a l examples of the relation between time and conversion for two different concentrations of D H A and 4 V P are presented i n Figure 2. Conversion increased linearly without any induction period, and the reaction was very fast i n the early stages. T h e rate of copolymerization increased w i t h the con centration of 4 V P . In the D H A - 4 V P studies, we found that copolymer yield and inherent viscosity varied considerably with the solvent used for polymerization (Table I ) . Solvents greatly affect free radical polymerization, although the mechanisms of some interactions is uncertain. F o r example, the effect of solvents o n the rate of polymerization has been attributed to complex formation and to vis cosity effects w h i c h alter rates of initiation, propagation, and termination (13, 14, 15). T h e data i n Table I do not indicate any clear tendency, and no molec ular weight-conversion correlation of the copolymers is apparent. T h e variation i n copolymer yields is readily explained b y differences i n solubility of D H A .
134
COPOLYMERS,
Table I.
POLYBLENDS, A N D COMPOSITES
Effect of Solvents o n the Copolymerization of D H A w i t h 4 V P Solvent
Conversion, %
Viscosity, vinh
Solubility at 25°C,g/dl
Benzene 2-Ethoxyethanol 2-Propanol Dimethvlformamide Acetonitrile
3.7 19.0 23.8 13.0 0.6
0.34 0.32 0.31 0.48 0.28
1.0 23.0 25.0 18.0 8.4
a
Polymerization conditions: 40 mole % D H A , 6 0 ° C , 3 hr, and A I B N 2 wt % of total monomer.
a
D H A - N V P S Y S T E M . W e conducted several copolymerization experiments to high conversion i n order to examine some characteristics of the systems and to determine some properties of the formed copolymers. T h e findings are sum marized i n Table II. The purified poly ( D H A - c o - N V P ) materials were white, powdery solids completely soluble i n water, alcohols, chloroform, D M F , a n d D M S O and insoluble i n acetone, benzene, and ether. T h e copolymers h a d good film-forming properties, i.e. air-dried films were clear and hard with a high gloss. The inherent viscosity of the D H A - N V P copolymer solutions varied with the feed composition (see Tables II and I V ) ; the value was m i n i m u m for 80 mole % D H A i n the monomer feed. Similar behavior, i.e. decrease i n mo lecular weight with increase i n D H A content i n feed, was observed for the D H A - 4 V P systems. This is further evidence of D H A participation i n lowering molecular weight b y increased monomer-induced chain transfer reactions. The I R spectra of the copolymers had strong absorption bands at 1710 cm (pyrrolidone unit) and 1580 c m " (aminimide carbonyl). W h e n films of the copolymers were heated ( 1 5 0 ° - 2 0 0 ° C ) , the band at 1580 c m vanished and a new strong band appeared at 2250 c m " w h i c h was indicative of the described aminimide-isocyanate rearrangement. A g a i n , the N M R spectra had poor resolution but the broad bands indicated D H A and N V P moieties. The D T A thermograms for D H A - N V P copolymers had endotherms near 120°C w h i c h could be associated with water loss. [Poly ( N V P ) is reported to have a very high affinity for water absorption.] However, these endotherms were also observed on carefully dried samples, and no weight loss was noted on the T G A curves. Unfortunately, the D T A samples could not be recycled since the copolymers underwent the rearrangement reaction. It may be argued that the endotherm was associated with the glass transition temperature of the materials. However, additional work is required to answer this question. Exo thermic activity followed at 1 5 0 ° - 2 4 0 ° C (midpoint, 1 8 5 ° C ) , w h i c h was also attributable to the aminimide-isocyanate rearrangement. T h e T G A curves, - 1
1
- 1
1
Table I I . Feed, % DHA
20 30 40 50 60 a b
Copolymerization of D H A w i t h N V P to H i g h Conversion" Time, hrs
Conversion,
%
Copolymer, mole % DHA
2.67 2.27 2.15 2.00 2.00
70 85 92 78 87
25 35 43 54 62
Viscosity,
Vinh 0.28 0.24 0.22 —
0.19
Polymerization conditions: 7 0 ° C , and A I B N 2 wt % of total monomer. Obtained on D u P o n t T-68 1300/3 cord.
Adhesion H Values, lbs b
27.1 28.9 33.9 37.8 35.9
12.
LANGER
A N D CULBERTSON
Table III.
Copolymerization of D H A (Μχ) w i t h 4 V P (M ,) to L o w Conversions" L
DHA, înoles
4VP, moles
DHA in Monomer Feed, mole %
0.01 0.02 0.03 0.04 0.06 0.08 0.10 0.12 0.14 0.16
0.19 0.18 0.17 0.16 0.14 0.12 0.10 0.08 0.06 0.04
5 10 15 20 30 40 50 60 70 80
a
135
Aminimides
Con version,
4.80 9.00 5.30 6.25 8.00 3.50 1.00 7.15 3.14 9.60
%
0 Content DHA in of Copolymer, Polymer, mole % wt %
3.48 4.48 5.44 5.98 7.11 7.80 9.03 10.51 12.24 13.91
12.54 16.60 20.73 23.15 28.27 31.95 38.48 47.08 58.34 70.62
Time, min
Copolymer Mole Ratio
60 70 80 80 90 60 40 90 60 90
0.143 0.199 0.262 0.301 0.394 0.469 0.625 0.889 1.400 2.404
Polymerization conditions: 2-propanol. 7 0 ° C , and A I B N 1 wt % of total monomer.
w i t h onset of weight loss at ca. 150°C, support this interpretation and show almost theoretical weight loss ( 1 5 0 ° - 2 5 0 ° C ) for amine. Reactivity Ratio Studies. D H A - 4 V P S Y S T E M . A series of D H A - 4 V P ( M - M ) copolymerizations was carried out to l o w conversions ( < 1 0 % ) w i t h the monomer pair ratio being varied. Table III summarizes the data. In the corresponding copolymerization diagram, the composition of the copolymer is plotted as a function of the composition of the initial monomer concentration 1
2
MOLE FRACTION OF DHA IN MONOMER
Figure 3.
Copolymer composition curves
, DHA-4VP
and
,
DHA-NVP
136
COPOLYMERS, POLYBLENDS, A N D COMPOSITES
Table I V .
Copolymerization of D H A ( Μ ) w i t h N V P ( M ) to L o w Conversions χ
2
a
DHA, moles
NVP, moles
DHA in M onomer Feed, mole %
0.03 0.04 0.06 0.08 0.10 0.12 0.14 0.16
0.17 0.16 0.14 0.12 0.10 0.08 0.06 0.04
15 20 30 40 50 60 70 80
a
Con version,
8.60 9.40 10.00 10.00 5.40 7.40 2.67 4.92
%
Copolymer Analysis, DHA in meq. Polymer, DHA mole %
2.09 2.59 3.03 3.41 3.63 3.90 4.05 4.25
Copolymer Viscosity, Mole Ratio Vinh
0.380 0.558 0.775 1.038 1.215 1.597 1.831 2.268
27.55 35.82 43.66 50.94 55.40 61.50 64.68 69.40
— —
0.45 0.41 0.36 0.29 0.27 0.19
Polymerization conditions: 2-propanol, 6 0 ° C , and A I B N 1 wt % of total monomer.
( Figure 3 ). This monomer pair had an azeotropic copolymerization composition at ca. 26 mole % D H A . Using the data i n Table III, the general copolymer composition equations, and the Fineman-Ross procedure (16), the reactivity ratios were estimated at r = 0.40 and 0.42 and r = 0.78 and 0.75 with mean values of 0.41 and 0.77 respectively. Values of r = 0.406 and r — 0.773 were calculated b y a com puter program based on least squares. The A l f r e y - P r i c e Q and e values (17) were calculated from the monomer reactivity ratios i n the copolymerization with 4 V P : Q = 0.68 and e = 0.58. The values used for 4 V P i n the calculations were Q = 0.90 and e = —0.50 ( 9 ) . D H A - N V P S Y S T E M . T h e results from a similar series of copolymerizations of D H A ( M J with N V P ( M ) are presented i n Table I V (see Figure 3 for the copolymer composition curve ). This system had an azeotropic copolymeriza tion composition at a much higher D H A content (ca. 60 mole % ). T h e differ ential form of the copolymer equation and the data i n Table I V were used to calculate the reactivity ratios: τ = 0.37 and 0.33 and r = 0.16 and 0.14 with average values of 0.35 and 0.15 respectively. Values of r = 0.352 and r = 0.145 were calculated b y the computer program. Using the values Q = 0.14 and e = —1.14 for N V P (10), the calculated Q and e values for D H A i n this system were Q = 0.14 and e — 0.58. The data from these two studies of monomer reactivity with D H A , as well as data from a previous study i n w h i c h M was methyl methacrylate ( M M A ) and D M F the solvent, are summarized i n Table V . W h e n possible variations i n the Q and e values estimated a n d used for N V P and 4 V P are taken into account, and also that some deviation might be caused b y the tem perature difference, the agreement between the two Q and e± values for D H A found i n this study was satisfactory. However, there was no reasonable corre lation between the Q and e values for D H A obtained w i t h comonomer M M A . It is possible that some monomer-monomer or monomer-solvent interactions may account for this discrepancy, but we detected no proof of such interactions. x
2
2
1
1
1
2
2
2
2
λ
2
l
2
2
1
1
2
2
2
1
1
Table V . Comonomer (71/2)
NVP 4VP MMA
x
Reactivity Ratios and Q and e Values for D H A ( M ) x
Π
0.35 0.41 0.00
r>
Qi
e\
0.15 0.77 1.99
0.14 0.68 0.12
0.58 0.58 -2.45
12.
LANGER
A N D CULBERTSON
137
Aininimides
(1)
CH +
Ν—CH CHCH 2
CH
3
;
O H
Copolymer Reactions. R E A R R A N G E M E N T R E A C T I O N S . T W O p o l y ( D H A - c o 4 V P ) materials w i t h 10-15 mole % D H A were thermolyzed i n refluxing D M F (see Reaction 1 ) . A strong nitrogen sparge was used to help remove the tertiary amine. T h e isolated poly ( 4-vinylpyridine-co-isopropenyl isocyanate) materials were insoluble in ether but soluble i n chloroform, they h a d a strong band i n the I R spectra at 2260 c m and a weak band at 1710 c m " , and they consisted of 1.5-2.0 wt % N C O . A sample of the thermolysis solution h a d a shelf life, i.e. lack of gelation, of about five days. U s i n g the same procedure, a sample of poly ( D H A - c o - N V P ) w i t h 20 mole % D H A was rearranged i n refluxing cyclohexanone (Reaction 2 ) . A sample 1
CH
1
3
(2) CH
3
/ Ν—CH CHCH \ I CH O H 2
3
of the isolated poly (N-vinylpyrrolidone-co-isopropenyl isocyanate) h a d a strong absorption band i n the I R spectra at 2250 c m " . Titration of the isocyanate indicated that the N C O content was 3.25 wt % . T h e shelf life of the unstabilized polymer solution was also about five days. Q U A T E R N I Z A T I O N S T U D I E S . Quaternization of D H A - 4 V P copolymers w i t h methyl chloride and methyl chloroacetate (Table V I ) produced water-soluble, polycation-containing materials with the idealized structure: 1
138
COPOLYMERS,
POLYBLENDS, A N D COMPOSITES
CH I —(CH —CH—(—CH —C—) — 2
2
y
CH
3
CONN—CH CHCH 2
\
CH
3
I 3
OH
R = CH , CH C0 CH 3
2
2
3
In methanol, the viscosities of the polycation materials resembled those of other polyelectrolytes (18), i.e. the inherent viscosity of a typical sample i n creased from 0.41 to 0.64 upon dilution from 0.5 to 0.125 g/dl. T h e I R spectra of the quaternized copolymers had aminimide absorption bands at 1585 c m " (as i n the original p o l y m e r ) , a strong band at 1650 c m " (pyridine r i n g ) , and, with — C H C 0 C H , a strong band at 1750 c m " . 1
1
2
2
Table V I . Copolymer, mole %4VP
40 40 60 60 60 a
1
3
Quaternization of D H A - 4 V P Copolymers
Alkylating Agent
CH CH CH CH CH
3
C1 C1C0 C1C0 C1C() C1C()
2
2
2
2
2
2
2
2
CH CH CH CH
3 3 3 3
T, °C 60 64 25 25 64
Time, hrs
Quat.,
3 1 1 12 3
68.5 66.0
a
% —
36.0 91.5
Calculated from CI analysis and based on 4 V P .
Complete quaternization ( D H A included) could not be obtained, w h i c h may be explained b y a low reactivity of D H A for alkylating agents or a decreased overall reaction rate. Fuoss and co-workers (19) observed strong, neighbor group effects i n quaternization studies of p o l y ( 4 V P ) . A s the quaternization proceeded, the rate decreased as a result of the charge buildup on the polymer, and quaternization of the last half of the pyridine ring nitrogen occurred at about one-tenth the initial rate. A D H E S I V E S T U D I E S . T h e D H A - 4 V P copolymers h a d excellent properties as adhesion promoters for rubber-steel (brass-coated) composites (Table V I I ) . The adhesion values of 44.8-47.6 lbs approach the limit of the test, i.e. rubber failure may occur at 45-50 lbs. T h e adhesion values listed i n Table V I I are the optima obtained i n numerous tests i n w h i c h p H , type of R F latex resin, curing temperatures, etc. were varied. Adhesion values ranged from the lower forties to the upper thirties, and coverages were i n the 3 + range. The quaternized D H A - 4 V P copolymers were very useful for promoting adhesion of rubber to polyester cord (Table V I I I ) . T h e D H A - N V P copolymers were also tested as adhesion promoters for polyester-rubber composites. T h e Table V I I .
Static Adhesion D a t a for D H A - 4 V P Copolymers on Brass-Plated Steel W i r e a
Polymer
Composition, mole %
Adhesion Value, lbs
DHA-4VP DHA-4VP
60/40 60/40
46.5 47.6
a
R F performed in situ.
Rubber Coverage, 0-5
4.4 4.4
12.
LANGER
Table VIII.
A N D CULBERTSON
139
Aminimides
Quaternized D H A - 4 V P Copolymers i n Polyester C o r d Adhesives
Copolymer, mole % 4VP
Quat., %
Adhesion H Values, lbs
a
60 40 40
66 89 36
36.4 38.0 40.0
Rubber Coverage, % 90 100 100
B
C
C
« Alkylating agent C H 2 C I C O 2 C H 3 , quaternization with respect to 4 V P . Tested on polyester cord F I T-785-1000/3. Tested on polyester cord DuPont T-68-1300/3. b c
data (Table II) indicate that there h a d to be ca. 50 mole % D H A i n the copolymer for the adhesion values to be comparable to those of the quaternized D H A - 4 V P copolymers. Several terpolymers of D H A and N V P with H E A , H E M A , H P M A , or G M A were prepared and evaluated as film formers and adhesion promoters for poly ester-rubber systems. A l l the copolymers were water soluble. However, cast films became water insoluble when heated ( 1 5 0 ° - 2 0 0 ° C ) because of the crosslinking reactions between isocyanate-hydroxyl or isocyanate-epoxide residues. Data from the terpolymerization experiments are presented i n Table I X . C O A T I N G STUDIES. Coatings were prepared from blends of poly ( D H A - c o N V P ) materials and expoxide resins. Typically, a 50:50 copolymer was dis solved i n methanol and combined with E p o n 812 (Shell Chemical) to give approximately 1:1 aminimide:epoxide. T h e solution was used to coat steel and glass panels to a thickness of ca. 1 m i l after air drying and baking 30 m i n at 160°C. T h e coatings h a d high gloss, adhesion, H pencil hardness, 40-lb face impact, 20-lb reverse impact, and excellent mar resistance, and they passed the conical flex test. T h e good solvent resistance indicated that the films were crosslinked. Summary D H A monomer copolymerizes readily with both 4 V P and N V P to form two new reactive polymers. The copolymers are easily obtained i n high yield, with polymerization rates and molecular weights strongly affected by initial monomer feeds. Reactivity ratio studies, with r — 0.41 and r = 0.77 for D H A - c o - 4 V P and r = 0.35 and r> = 0.15 for D H A - c o - N V P , clearly demon strate that alternating copolymers are obtained. 1
2
L
x
Roth D H A - c o - 4 V P and D H A - c o - N V P materials with low D H A content were thermolyzed i n solution to give soluble, reactive 4VP-co-isopropenyl iso cyanate
a n d NVP-co-isopropenyl isocyanate
copolymers.
The DHA-co-4VP
copolymers were quaternized to give new cationic polyelectrolytes with properTable IX. Monomers D D D D
H H H H
A A A A
-
N N N N
V V V V
P P P P
-
H H H G
EA E M A PMA MA
Terpolymers of D H A and N V P Time, hrs
Conversion,
5 3 5 3
50 51 60 50
%
H
n
A dhesion Values, lbs 33.6* 37.7 33.2 40.6 C
C
6
Rubber Coverage, 100 100 —
97
Polymerization conditions: 50:40:10 mole / monomer feed, methanol (50% solids), 7 0 ° C , and A I B N 1 wt % of total monomer. Tested on polyester cord D u P o n t T-68-1300/3. Tested on polyester cord FI-T-785-1000/3. α
b
c
c
(
140
COPOLYMERS,
POLYBLENDS, A N D COMPOSITES
ties w h i c h could be greatly modified by adjusting copolymer composition, degree of quaternization, and type of alkylating reagent. These copolymers have a wide range of possible applications. D H A - c o 4 V P and D H A - c o - N V P copolymers are excellent for rubber-steel and r u b b e r polyester adhesive systems respectively. I n addition, quaternized D H A - c o - 4 V P copolymers promote strong adhesion of rubber to polyester tire cord i n v u l canized composites. Acknowledgment The authors wish to acknowledge the help and encouragement of W . J. M c K i l l i p i n this work, P . M e n a r d i for N M R , M . Hallwachs for G P C , D . Gregerson for D T A and T G A experimental work, E . L u c k m a n a n d R . E . F i e l d for excellent technical assistance i n the adhesive studies, a n d B . Bushong for general synthesis work. Literature
Cited
1. McKillip, W . J., Sedor, Ε . Α., Culbertson, B. M . , Wawzonek, S., Chem. Rev. (1973)73,278. 2. Metallgesellschaft A.G., Brit. Patent 943,156 (1963); Chem. Abstr. (1964) 60, 7012c. 3. Keskula, H., U.S. Patent 3,072,598 (1963); Chem. Abstr. (1963) 58, 7000a. 4. Wolfe, W . D., U.S. Patent 2,817,616 (1957); Chem. Abstr. (1958) 52, 5019d. 5. Lorenz, D. H . , in "Encyclopedia of Polymer Science and Technology," Ν. M . Bikales, Ed., Vol. 14, p. 239, Interscience, New York, 1971. 6. Morner, R. R., Longley, R. I., U.S. Patent 2,667,473 (1954); Chem. Abstr. (1954) 48, 6164. 7. Takemoto, K., J. Macromol. Sci. Rev. Macromol. Chem. (1970) 5(1), 33. 8. Culbertson, Β. M . , Sedor, Ε. Α., Slagel, R. C., Macromolecules (1968) 1, 254. 9. Tamikado, T., J. Polym. Sci. (1960) 43, 489. 10. Young, L . J., J. Polym. Sci. (1961) 54, 411. 11. Culbertson, Β. M . , Slagel, R. C., J. Polym. Sci. Part A-1 (1968) 6, 363. 12. Culbertson, B. M . , Freis, R. E . , Macromolecules (1970) 3, 715. 13. Schultz, G. V., Fischer, J. P., Makromol. Chem. (1967) 107, 253. 14. Bengough, W . I., Henderson, Ν. K., Chem. Ind. London (1969) 20, 657. 15. Burnett, G. M . , Cameron, G. G., Parker, R. M . , Eur. Polym. J. (1969) 5, 231. 16. Fineman, M . , Ross, S. D., J. Polym. Sci. (1950) 5, 259. 17. Alfrey, Jr., T., Price, C. C., J. Polym. Sci. (1947) 2, 101. 18. Flory, P. J., "Principles of Polymer Chemistry," p. 635, Cornell University, Ithaca, 1967. 19. Fuoss, R. M . , Watanabe, M., Coleman, B. D., J. Polym. Sci. (1960) 48, 5. RECEIVED April 1, 1974.
