CA1068038A

CA1068038A - Polyacrylic hot melt adhesives

Info

Publication number: CA1068038A
Application number: CA264,433A
Authority: CA
Inventors: John D. Guerin; Thomas W. Hutton; John J. Miller; Richard E. Zdanowski
Original assignee: Rohm and Haas Co
Current assignee: Rohm and Haas Co
Priority date: 1975-11-24
Filing date: 1976-10-29
Publication date: 1979-12-11
Also published as: DE2653184A1; AU1991676A; MX4551E; US4152189A; JPS6047301B2; AU513061B2; JPS5265549A; GB1557289A; FR2332300B1; NZ182696A; US4045517A; FR2332300A1

Abstract

ABSTRACT OF THE DISCLOSURE

Novel polyacrylic hot melt adhesives prepared by blending a polymer having a Tg of -85° to 0°C. with a polymer having a Tg of 20° to 150°C. are disclosed.

Description

l(~V;:~

I`his invention relates to novel polyacryllc hot melt adhesives and to methods for preparing same.
Adhesives can be divided into three categories:
solvent borne, water borne and 100% solids. Materials in the first two categories must be subjected to a vehicle removal process, subsequent to coating and/or laminating operations. In the case of water borne adhesives, this procedure is uneconomical in terms of energy and time consumption. Solvent borne adhesives are somewhat more economical in this respect requiring less time and energy, -however, the solvent removal process presents pollution, fire and explosion hazards. Hot melts are essentially 100%
solids adhesives and therefore no vehicle removal opera-tions are necessary. These materials are applied in a molten state and are then cooled rapidly with the aid of a chill roll. Therefore, coating or laminating operations can be conducted at higher speeds with less equipment, lower energy consumption and greater safety than with vehicle borne adhesives.
Most hot melt adhesives (particularly pressure sensitive adhesives) are blends of elastomers with plasti-cizer and tackifiér resins derived from natural rosins.
These adheslves generally exhibit poor clarity and deep coloration or both which are undesirable in applications wherein the adhesive will be visible (e.g., transparent laminations). Many of the elastomers employed in these adhesives contain unsaturated chemical bonds (e.g., styrene-butadiene block copolymers), these bonds are vulnerable to attack by oxygen and ultraviolet radiation.
This vulnerability contributes to loss of adhesive properties and discoloration on ageing, particularly in outdoor applications.

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The term "hot melts" as employed here is meant to include both pressure sensitive adhesives and laminating adhesives. An excellent compendium of hot melt adhesives is contained in the book Hot Melt Adhesives, Noyes Data Corporation (1974).
The novel polyacrylic hot melt adhesives of thé
instant invention require no nonacrylic additives, are only very lightly colored and are substantially insensitive -toward oxidation and ultravi~let exposure.
The polyacrylic hot melt adhesives of the invention are compositions comprising a blend of: ;
A. from 5 to about 95 parts by weight of an addition copolymer having a Tg in the range of from about 0 to about -85C. comprising: ~ -1. from about 85 to 99.5 parts by weight of a monomer or monomers selected from alkyl (Cl 18) or alkoxyalkyl abrylate which may also contain minor amounts of alkyl methacrylates, alkoxyalkyI methacrylates, styrene, acrylonitrile, vinyl acetate, vinyl chloride, vinylidene ~; - ;
chloride, ethylene, butadiene, isoprene, vinyl ether and the like;
2. from about 0.5 to about 15 parts by weight of an ethylenically unsaturated amine, carboxylic acid or sulfonic acid or mixtures thereof with B. from about 5 to about 95 parts by welght of an addition copolymer having a Tg in the range of from about 20 to about 150 C. and comprising:
1. from about 85 to about 99.5 parts by weight of a monomer or monomers selected from a monomer ~ -of the formula: R 1 CH2=C-., . . ,,., , ~,~ :

~068038 (Cl 5), lower cycloalkyl (C5 6) or isobornyl,or styren3, acrylonitril~, vinyl acetate, vinyl chlo.ride, vinylidene chloride, ethylene, butadiene, isoprene, vinyl ether and the likeand (2) from about 0.5 to about 15 parts by : -weight of an ethylenically unsaturated carboxylic or sulfonic acid or an amine or mixtures thereof. -~
Preferred hot melt adhesive compositions of -this invention comprise a blend of: . .
A. from about 35 to about 90 parts by weight , . ~ ..
of a copolymer having a Tg in the range of from -20C.
to about ~5C. comprising:
(1) from about 88 to::about 98.5 parts by weight of a lower alkyl acrylate (Cl 8) and (2) from about 1.5 to about 12 parts by .weight of an ethylenically unsaturated acid or amine with .. B. from about 10 to about 65 parts by weight of a copolymer having a Tg of 35C. or more preferably . in the range of from about 3~C. to about 110C. comprising:
(1) from about 88 to 98.5 parts by weight of the monomer of the formula:

CH2=C -C02R
wherein R is hydrogen or methyl and R is lower alkyl, lower cycloalkyl or isobornyl and (2) from about 1.5 t~ about 12 parts by ..
weight of an ethylenically unsaturate~ carboxylic acid or amine.
Pressure sensitive adhesives can best be prepared employing from about 15 to about 30 parts by weight of Copolymer B, supra whereas blends containirg 1~6~30 3 ~

greater than 30 parts by weight of Copolymer B, supra, are suitable for use as nontacky laminating adhesives.
Especially preferred are compositlons comprising a blend of:
A. from ab3ut 60 to ab~ut 85 parts by weight of a copolymer comprising:
lo from about 94 to 98 parts by weight of a monomer selected from butyl acrylate, 2-ethylhQxyl acrylate, methyl acrylate, ethyl acrylate, isobutyl 10 acrylate isoamyl acrylate or _-propyl acrylate and ~ -2. from about 2 to about 6 p~rts by weight of dimethylaminoethyl acrylate or methacrylate, diethyl- ~-aminosthyl acrylate or methacrylate or tert-butylaminoethyl methacrylate with B. from aboutl5 to about ~0 parts by weight of ~ -a copoiymer comprising:
1. from about 9~ to 98 parts by weight of isobutyl methacrylate, isobornyl acrylate, isobornyl meth-acrylate, methyl methacrylate and the like and ~ ' 2. 20 from about 2 to 6 parts by weight of anacid selected from methacrylic acid, acrylic acid or itaconic acid. ;~
The preferred systems are compatible, that is one o~ the polymers is soluble or substantially solubls ln the other polymer. To determine compatibility a 30%
solution of the copolym¢rs is prepared in a suitable solvent such as toluene and the like, blended in the desired proportions and spread on a glass plate at a thickness of about 20 mils. The blend is allowed to air dry for one half ':~

~ 5 ~
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hour, dried in a 150C. oven for three hours, allowed to cool and examined visually for clarity. ~he systems are considered compatible if they form a substantially clear film.
The viscosity of the blends at 177C. (350F.) at 100% solids is generally in the range of from about 1,000 to about 1,000,000 cps with the preferred blends having -viscosities in the range of from about 1,000 to about 250,000 cps.
Blending is preferred since we have found that forming a single polymer from the same ratios of monomers as in a blend affords very poor if not totally unsuitable hot melt adhesive.
Examples of acrylate monomers whlch form ;~
15 polymers having low Tgs include the methyl, ethyl, n- --propyl, isopropyl, isobutyl, sec-butyl, n-butyl, n-pentyl, 2-ethylhexyl, methoxyethyl and ethoxyethyl acrylates.
Examples of monomers which form polymers having Tgs of 20~ to 150C. include tert-butyl acrylate, cyclo-20 hexyl acrylate and methacrylate also included are the methyl, ethyl, _-propyl, i-propyl, _-butyl, i-butyl, sec butyl, tert-butyl, isopentyl, cyclohexyl and isobornyl methacrylates.
The ethylenically unsaturated containing carboxylic acid, su~fonic acid or amine employed in the preparation -of the copolymers are monomers having the following formula:

CH2=C-X

wherei~ R is hydrogen, methyl or carboxy and X is mono-or di-lower alkylamino lower alkoxy carbonyl su~h as di-methylaminoethoxycarbonyl, diethylaminoethoxycarbonyl, ^ -G- `

.. . . . . ~ ~ .. . . ~ - .

106803~
tert-butylaminoethoxycarbonyl and the like, sulfo lower alkoxycarbonyl such as 2-sulfoethoxycarbonyl and the like, a 5- or 6-membered heterocyclic amine radical such as 2 or 4-pyridyl, 2-quinolyl and the like, carboxy, lower alkoxy carbonyl methyl, such as methoxycarbonylmethyl, ~ -ethoxycarbonylmethyl, propoxycarbonylmethyl, butoxycarbonyl-methyl and the like or carboxy lower alkyl such as carboxy- `
methyl and the like. While in general either an acid or amine or a mixture thereof will afford adhesives, it is preferred that the copolymers with the high Tgs contain the acid and the copolymers with low Tgs contain the amine.
Examples of the carboxylic acids, suIfonic acids or amines which can be employed include acrylic acid, methacrylic acid, itaconic acid and its alkyl esters such as the methyl, ethyl, propyl, n-butyl esters and the like, 2-sulfoethyl methacrylate, tert-butylaminoethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl meth-acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, 2- or 4 pyridine, 2-vinylquinoline and the like.
The copolymers embodied herein may be prepared by mass (or bulk), emulsion, suspension of solution polymeriza-tion techniques. For the purposes of this invention, solution polymerization and especially sequential solution polymeriza- `
tion is preferred beaause of the superior adhesive properties of the resulting polymer.

-7- `

V31~
It has been found that by conducting solution polymerizations at reflux temperatures in the presence of . - -water, higher molecular weight polymers are obtained. The addition of water to the reaction mixture lowers the reflux temperature of the reaction mixture; slows the rate of de-composition in the initiator employed in the polymerization and because the reaction is conducted at reflux, the oxygen of the air is excluded from the reaction.
The amount of water employed is dependent upon the initiator, solvent, type of monomers employed and con-centration of monomers. In general, water is employed in the ~;-range of from about 0.1 parts per 100 parts of total monomer employed to about 5.0 parts and, preferably, in the range of ;~
from 0.1 to 1.0 parts.
The most preferred procedure is not to add the water in one portion but to add water initially in the range of from about 0.1 to about 0.30 parts with subsequent multiple additions of water in the range of from about 0.01 to about 0.12 parts whenever the reflux temperature begins to exceed -the desired reaction temperature.

Solvents which can be employed in these solution polymerizations are, in general, organic solvents which when containing water reflux at a lower temperature than when they are anhydrous. Examples of solvents which can be employed -include aromatic hydrocarbons, such as benzene, toluene, xylene, mesitylene and the like; aliphatic hydrocarbons, such as butane, pentane, hexane, heptane, isooctane and the like, ketones, such as methylethyl ketone, methylisobutyl ketone and the like; esters, such as ethyl acetate, propyl acetate, butyl acetate, ethyl propionate and the like; ethers, such as butyl ether, anisole and butoxyethanol; alcohols such , ., , . ~ . . .

V;~8 as butanol, pentanol and the like; halogenated aliphatic hydrocarbons such as chloroform and the like and mixtures of same.
1he preferred procedure is to conduct the polymerization in the solvent toluene at a temperature in the range of from about 112 to about 118 C.
In the preparation of the blends it has been -found that in sequential solution polymerizations water can ~ ;`
be added to any or all of the copolymerizations. For example, in the preparation of hot melt adhesives, either Copolymer A
or Copolymer B can be formed f1rst and that the addition of water at either or both polymerization steps involved causes an increase to the molecular weight of the copolymer. It is preferred, however, to add water to the second monomer mix to form higher molecular weight Copolymer A (Tg = -85 to 0 C.).
As polymerization catalyst there may be used one or more peroxides which are known to act as free radical catalysts and which have solubility in aqueous solutions of the emulsifier. Highly convenient are the persulfates, including ammonium, sodium and potassium persulfates or hydrogen peroxide or the perborates or percarbonates. Preferred are the organic peroxides used in solution polymerizations including benzoyl peroxide, tert-butyl hydroperoxide, cumene peroxide, tetralin peroxide, acetyl peroxide, caproyl peroxide, tert-butyl peracetate, tert-butyl perbenzoate, tert-butyl diperpthalate, tert-butyl peroctoate, methylethyl ketone peroxide, tert-butyl per-pivalate and the like. `
The usual range of catalyst employed is from about 0.01% to about 3~ of catalyst with reference to the weight of the monomer mixture. The preferred range is from -about 0.02 to about 1.0% with the range of from about 0.05 ~ o ` -.

` 1068~3~
to about o. 8% bsing most preferred. ~ne optimum amount of cat-~lyst is d termined in large part by the nat~e of the particular monomers employed including lmpurities which accompany particular monomsrs.
~hese systems, though normally employed as 100%
solids, can, if nseded, also be applied b-J dissol~ing i~ a suitable so~e~t lncluding tol~ene xylen~, acetone, methyl-ethyl ketone, methylisobutyl ketQne. halogenated nydro-carbons such as chloro~orm, dichloroethane ~nd the like.
; 10 While, i~ general, no additi~es are needed, the following ma~
be employed:
adhesl~e agents, such as colophonium, phe~ol resi~s? natural resin, ~ coumarone-indene resin, . . . . . .. . .. . . .. . .. . _ . . .. __ _ .
. rosinester and hydrated rosin derivatives may be incorporated;
. . _ .. . .. .. . _ _ . .. ._. .. _ . . _ ._ ... _ . _ .. _ _ _ _ _ 1~ fillers and pigme~ts may be added t~ obtai~ needed~
properties. ~pical f~llers i~clude: powdered ~uartz, pelrl . white barium sul~ate, light spar (gypsum), chalk a~d the li~e and antioxid~ts, ultraviolet inhibitors, plasticizers and pigments may also be employed.

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106803~
PREPARATION OF POLY~ERS HAVING T~'s OF 0C. AND LESS
E~AMPLE 1 - Co~olYmer of BUtYl acr.vlate and Methacrvlic Acid A monomer m.ix is prepared from butyl acrylate (98 parts), methacrylic acid (2 parts), tert-butyl per- .
octoate (0.1 parts) and hy~roxyethyl mercaptan (0.05 parts).
To a flas~ containing toluene (19.3 parts) is added 15 ~.
parts of the monomer mix and the contents heated to 110C.
with stirring. ~ne remainder of the monomer mix is added ~-~
: at a constant rate over a three hour period at 110C. The poly.mer.ization mixture is held at 110C. for 30 minu~es and then treated during 30 minutes with a solution prepared ... . ~
from toluene (0.83 parts) and tert-butyl ~eroctoate (0.2 ~ -parts). After the mixture is held at 110C. for 30 minutes longsr and then cooled, there is obtained a solution containing 53.2% by weight of polymer represent~
ing a conversion of 100%. The Brook~ield Viscosity of the ~ solution at three rpm is 162,000 cps.
Z By follo~ing substantially the procedure of Example 1, the copoly~srs with a Tg of 0 or less ..
described in Iable I are prepared.

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EXAM~LE 9 - Cop~lymer of Butyl acrylate and tert-Butyl-aminoetll~l methacrYl~te A solution of toluene (19.3 parts), butyl acrylate(l2.4 parts), tert-butylaminosthyl methacrylate (2.58 parts) and 0.10 parts of a 75% solutio~ of tert-butyl perpivalate contained in a flask is heated to 92C.
with stirring for 30 minutes. A monomer mix containing butyl acrylate (70.4 parts), tert-butylaminoethyl meth-acrylate (14.6 parts) and 0.228 parts of a 75,~ solution of ~-tert-butyl perpivalate is then added at a constant rate over three hours to the stirred reaction mixture at 92C.
The reaction mixture is maintained at 92C. for 30 minutes -~
while being diluted with toluene ~20 parts). A ch~ser catalyst of toluene (1.25 parts) and 0.20 parts of a 75%
solution of tert-butyl peripvalate is added over 30 minul}~s; ~
the reaction mixture is held at 92C. for 30 minutes ~ -following which it is cooled to afford a solution con- ~ ~
.~ -, , , taining 67.0% by weight of a polymer representing a ..
conversion of 94.5~ of the t~leoretical. The Brookfield `;-~
viscosity of the solution at six rpm is 13 ,~00 cps.
By following substantially the procedure as described in Example 9, the following soft polymers described in Table II are prepared.
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106803t~ 1 PREPARATION OF PO~YM~RS HAVI~G ~'s OF 20 to 150C.
. . . _ EXAMPLE 2~ - IsobutYl mathacrYlate and MethacrYlic Acid A monomer mixture is prepared fro~ isobutyl methacrylate (96.3 parts) arld methacrylic acid (3.7 parts).
A catalyst solution is prep~red from xylene (11.8 parts) and tert-butyl peroctoate (1.10 p~rts). To a flask e~uipped with a stirrer is added xylene (30.1 parts), 15.1 parts monomer mix and 1.4 parts catalyst solution. The contents are heated to 115C. at which point the remaining monomer solution and 7.96 parts catalyst solution are added at a constant rate o~er a two hour period with the reaction -mixture maintained at 115C. The remainder of the catalyst solution is added at a uniform rate over 30 minutes. After an additional 15 ~inutes at 115C., the reaction mixture is cooled and diluted with xylene (72 parts) to afford a solution containing 45.6~ by weight of polymer representing a conversion of 98.2% of the theoretical. The Brookfield viscosity of the solution at 30 rpm is 13,~40 cps. ~ -~
By follo-~ing substantially the procedure of Example 23, the products described in Iable III are prepared.

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EXAMPLE ~8 - Isobutyl methacrylate (96.3) - Itaconic Acid (~.7) _ _ To a flask equipped with a stirrer is added 2-methoxyethanol (12.3 parts), toluene (27.4 parts)ald itaconic acid (3.7 parts). ~he contents are hsated to re-flux and a monomer mix containing isobutyl methacrylate (96.3 parts), toluene (9.58 parts) and tert-butyl peroctoate (0.93 parts) are added at a constant rate over th-ee hours.
The reaction mixtures are held at reflux for 15 minutes, treàtéd ~ver a period of one hour with a solution of toluene (5.5 parts) and tert-butyl peroctoate (0.93 parts), diluted with toluene (10.5 parts) and then cooled to affo~d a poly~er solution containing 59.4% by weight of polymer representing a conversion of 93.9% of the theoretical. The Brookfield 15 viscoslty oi the solutlon at 30 rpm is l1,500 cps.

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FORM HOT MELT AHD3~IVE~
The poly~ers of Examples 1-23 and the polymers of Examples 23-38 are blended to afford compatible mixtures exhib.iting hot melt adhesive properties. The blending is accomplished by removing solvent from each polymer at 150-175C. and 5-10 tor. The required quantities of the in-dividual polymers are weighed into a beaker, heated to 175C.
and blended to afford the hot melt adhesives of Table IV.

' .: . . ................ .. ,,.... .,, ,........ . "., , .,~ ~, _ 20 _ `

1~)6803~ ~ ;
T~LE IV
Parts by weight of Pol y~ners of Poly~ners ofPolymers ofExam~OOs 23-38 Blen1 Example N~. Example No.of Mixture ~ 2 20 41 ~' 2 25 ~2 ~ 2 30 43 " 2 35 ' ~4` - ~ ~ 2 ~0 :: ;
" 15 20 46 - ~ 15 ~ 25 47 " 15 30 48 ~ 15 35 `
49 " 5 - 30 :
" 5 35 `
~ . .
51 " 5 40 52- ~ 6 30 `
53 " 6 35

5~ ~ 6 40 " 7 30 56 ~ 7 40 57 " 1 25 . :
58 " 1 30 .
59 ~ 1 35 .
" 1 40 .
61 2~ 1 40 ~ :~
62 " 1 50 63 " 1 60 --`
64 ~ 1 70 ~ 8 35 - ~: -~',' ' ., -. .

1068~3~3 ~
~ . .

TABLE IV. cont.
Parts b~ weight of Polym0rs of Blend Polym rs of Poly~ers of of Mixtu .. re 67 " 2 35 68 ~ 2 40 69 ~ ~ 30 ~70 ~ 5 35 ~ :
71 ~ ~ 5 ~o ~ :
72 .~ ~ 30 73 " 6 35 74 " 6 : 40 -" 7 30 .
76 " 7 35 77 " 7 40 79 " 2 35 ~ 2 40 81 " 5 3 82 " 5 35 83 '' 5 40 8~ " 7 30 " 7 35 86 ~ 7 ~o 87 ~7 5 3 88 " 5 35 89 " 5 ~
" 7 3 91 " 7 35 92 " 7 ~0 _ ~ _ - . . .. ..
~ ` . . .
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106803~

T~L~ cont.
Parts b~J weight of Polymers of Examples 23-38 Polymers of Per 100 Parts Polymers ofExample No of Mixture Blends Example No.

9~ ~ 2 35 " 2 40 96 " 5 3 97 " 5 35 98 " 5 40 99 " 6 30 100 1~ 6 ' 35 101 " 6 ~0 ~:;
102 " 7 3 103 1' ,7 35 10~ " 7 40 ;;

106 ~l 5 5 107 ~ 5 ~0 108 " 2 30 109 " 2 , 35 110 " 2 40 ;~
111 " 7 3 -112 " . 7 35 113 ~I 7 ~0 ;:

115 ~ 1 30 ~ .
116 ll 1 35 ~ :-.
117 " ~ 1 40 . -~
118 " 2 25 -:-~:
- ~3 - . ;

~068038 TA~LE IV, co~t.
Parts by weight of Poly~srs of Examples 23-38 Polymers of Polymers of Per 100 Parts Blends ExamP_e No. ExamPle No. of Nixtl1re 120 ~ 2 35 121 " 2 40 ;
122 " 3 123 ~ 3 20 124 " 4 10 125 " 4 20 126 " 4 25 127 " 4 30 ~;
28 ~ 8 35 :
129 31 10 25 ;~`
130 . ~ 10 30 131 " 10 35 ;
132 " 11 25 ,.
133 . 11 3 134 ~ 11 35 135 " 9 25 136 ll 9 137 " 9 35 -138 ~ 12 25 139 " 12 30 140 ll 12 35 141 ~ 13 25 142 " 13 3 143 " 3 35 ;;
144 " 14 25 . -- , .~-1068038 ~
TABLE IV~ cont.
Parts b~ weight of Polymers of Examples 23-38 Polymers of Polymers of Per 100 Parts Blends ExamPle No. ExamPle No. of Mlx~ture 146 ll 14 35 -148 " 10 30 149 ll 10 35 151 t~ 11 30 -; ~
152 ll 11 ~ 35 - ~ -153 I~ 9 25 154 ll 9 30 155 ll 9 ~ 35 -~
156 ~ 12 25 157 I~ - 12 - 3 I ;~
158 ~ 12 35 159 I ~ 13 25 r ~ ~
160 ~ 13 30 : -161 ~ 13 35 162 ll 14 25 163 ll 14 30 ` ~
1~4 1~ 14 35 I ;

166 ll 10 30 167 ~l 10 35 168 ll 11 25 169 ll 11 30 170 ll 11 35 171 ll 9 25 -'' _ ~5 _ -~
~, 10680;~8 TABLE l_ cont.
Parts b~J weight of Polymers o~
Exampl0s 23 -38 Pol~ers ofPolymers of Per 100 Parts Blend ExamPle No. Ex~m~le No. of MixtllrQ

173 " 9 35 174 ~I 12 25 175 " 12 30 176 I~ 12 35 177 " 13 25 178 ll 13 3 179 " 13 35 180 " 14 25 181 " 14 30 182 " 1~+ 35 18~+ " 2 30 185 ,. 2 35 ~ .
186 " 2 40 -188 " 2 25 189 " 2 , 30 190 ~ 2 35 192 " 16 25 193 " 16 30 195 " 16 )+0 196 " . 17 20 197 " 17 25 ~:
198 ~l 17 3 :
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2 6 - ~

_ _ , .. , , , ., . . . . ,, , , , , . , , _ ' 1068038 TA~LE IV~ cont. .
Parts b~ weight of Polymsrs of Examples 23-38 Polymers of Polymers of Por 100 Parts Blends Example No. Example No. of M~xtu~ ____ 200 " 17 40 201 " 18 20 ~ -202 " 18 25 ;~:
203 " 18 30 204 " 18 35 205 " 18 40 206 " 19 20 207 . "~ 19 5 ~ .
208 " 19 30 209 " . 19 35 ; .:
210 . " 19 ~0 ``:: -.. 211 " 20 15 .;
212 " 20 20 213 20 r 5 214 . " 20 30 215 " 20 35 216 " 21 20 217 " 21 25 218 " 21 30 219 " 21 35 220 " 21 40 222 " 17 25 223 " 17 30 224 " 17 35 225 " 17 ~

. . - 27 -, , - - , . - , . -.. , i .
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~0680;~3 , TABLE_IV, ~nt.
Parts by weight of Polym~rs of Examples 23-38 Poly~ers of Polymers of Per 100 Par .,s Blends ExamDle No. ExamPle No. of Mixture 22? 36 17 25 228 ~ 17 30 229 " 17 35 230 " 21 15 231 " 21 20 .
- 232 - " 21 25 233 " 21 . 3 234 " 21 ~ 35 :~
235 37 18 . 20 ~ . -236 " 18 25 ~ ~
237 " i8 ~ 3 : :
238 ~ 18 . 35 239 " 18 40 240 " 19 15 241 " 19 20 ~-242 " 19 25 243 " 19 30 244 '' 19 35 245 " 22 15 246 " 22 20 247 " 22 25 248 " 22 30 249 ,. 22 35 250 " 20 15 ~
251 " 20 20 ~ -252 " 20 25 253 " 20 30 25~+ .l 20 35 -- , . :... .
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BLENDIN~J 3~ SEQUENTIAL SO~UTION POEYMERIZA~-lON
~ he blends may also be prepared by a sequsntial solution polymerization 3f the monomer composition required for each phase. The low Tg monomers m~y bs polymerized first, followed by polymerizat~on of the high Tg monomers, as illustrated by Example I or the high Tg polymers and then the low ~g monomers may be polymerized as illustrated by Examples II through XII. The preferred method is the latter.
Blen~ds prepared by sequential polymerization of each phase : . .; - .
10 have performance equivalent or superior to blends of the -separately prepared polymers. ~ ~ -" . . :' -:
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Example I illustrates the sequential polymeriza-tion in which the soft phase is prepared first followed by the hard phase. The soft phase, butyl acrylate/tert-butyl-aminoethyl methacrylate = 95.7/4.3, to hard phase, isobutyl methacrylate (IBMA)/methacrylic acid (MAA) = 96.3/3.7, ratio is 72.5/27.5.
EXAMPLE I
A flask containing toluene (5.35 parts), butyl acrylate (10.4 parts), and tert-butylaminoethyl methacrylate (0.47 parts) is heated until the contents attain 105 C.
when tert-butyl peroctoate (0.012 parts dissolved in ~ -toluene 0.70 parts) is added. The solution is brought to reflux and held at reflux for forty minutes. A soft phase ~-monomer mix prepared from butylacrylate (59.0 parts), tert- ~ -butylaminoethyl methacrylate (2.65 parts), tert-butyl peroctoate (0.031 parts) and toluene (2.08 parts) is added ; -at a uniform rate over lOS minutes to the flask contents at reflux. Following a 15 minute hold period a chaser catalyst composed of 75% tert-butyl peracetate (0.19 parts) and toluene (0.59 parts) is added over a 45 minute period. ~he mixture is held at reflux ~5 minutes), diluted with toluene (1.24 parts). A hard phase monomer mix containing isobutyl meth-acrylate (26.5 parts), methacrylic acid (1.02 parts), toluene (3.58 parts) and 75% ~ -butyl peracetate (0.076 parts) is prepared and added at a uniform rate to the reaction mixture over a 50 minute period. Following a 15 minute hold period a chaser solution at 75% tert-butyl peracetate (0.37 parts) and ~-~
toluene (2.1 parts) is added at a uniform rate over 95 minutes.
After a 15 minute hold period the solution is cooled and it is found to contain 83.1% solids (96.6% overall conversion) and ~ 30 -'~

.: : - --. .-.-lVt;~039 to have a viscosity of 210,000 cps at 53C. The polymer blend is stripped of solvent on a flask-evaporator at 175C. and 5-10 torr.
Examples II through VII illustrate the sequential polymerization in which the hard phase is prepared first followed by the soft phase.
EXAMPLE II
A hard phase monomer mix is prepared from isobutyl ~ ~' methacrylate (26.5 parts), methacrylic acid (1.01 parts), '~
toluene (0.98 parts) and tert-butyl peroctoate (0.45 parts).
To a flask containing toluene (7.50 parts) is added 19.1%
of the monomer mix and the contents are heated to reflux ~ ,-(113C). Fifteen minutes later the addition of the remaining '~
monomer mix is started and continued at a constant rate over 40 `'~
minutes while the flask contents are stirred at reflux. The mixture is held at reflux f`or 15 minutes and then treated during 30 minutes with the addition a* a uniform rate of a ' solution prepared from toluene (1.33 parts~ and tert-butyl -;peroctoate (0.048 parts). Th~e solution is held at reflux for 15 minutes (122 C.) and then a'soft phase monomer mix is prepared from toluene (4.20 parts), butyl acrylate (69.39 ' parts), tert-buty,laminoethyl,methacrylate (3.11 parts) and 75% tert~butyl peracetate (0.049`parts) i9 added over 100 '' minutes at a uniform rate while keeping the flask contents at reflux. During the addition, the reaction temperature ~ , increases from 122 to 139 C. The reaction mixture is held at reflux for 15 minutes and then treated by the uniform 7 addition over 60 minutes of a solution containing toluene ' (2.84 parts) and 75% tert-butyl peracetate (0.20 parts). ~ -After the mixture is held at reflux for 15 minutes longer and then cooled, there is obtained a solution containing 85.5%

, :, 10~8038 by weight of` polymer representing a conversion of 100%. The product is concentrated on a flash evaporator at 175 C. and 3-5 torr. to a nominally 100% solids, highly viscous liquid.
, By following substantially the process of Example II
the sequentially polymerized hard soft copolymer blends of Examples III through VII are prepared, see Table V. Except for Example VII all of the Examples of Table V have the same hard and soft phase composition of Example II.

.. ."
TABLE V -Parts of Hard Viscosity Polymer per , at 100% ~
100 Parts of Solids and ~--Example No. Total Monomer Conversion (%) 177 C. (cps.) IV 25 . 99.7 6900 V 22.5 100 4000 .

VI 38.4 , VII 20 99.8 5100 "' :....... ... ' ;~ :.:
lHard phase composition: IBMA/MAA = 94.8/5.2 .
. .
., Example VIII illustrates the sequential polymeriza-tion in which the hard phase is prepared first followed by the soft phase; however, during the polymerization of the soft phase, water is added to reduce the reaction temperature with the result that a higher molecular weight soft phase is.
formed.

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EXAMPLE VIII
A hard phase monomer mix is prepared from isobutyl methacrylate (19.26 parts), methacrylic acid (0.74 parts), ; toluene (0.72 parts), and tert-butyl peroctoate (0.16 parts), -To a flask containing toluene (8.18 parts) is added 28.7%
of the monomer mix and the contents are heated -to reflux (115C.). Fifteen minutes later the addition of the remaining monomer mix is started and continued at a uniform rate over 40 . .
minutes while the flask contents are stirred at reflux. The mixture is held at reflux for 15 minutes and then treated during 30 minutes with the addition at a constant rate of a solution prepared from toluene (1.34 parts) and tert-butyl peroctoate (0.034 parts). The solution is held at reflux for 15 minutes (120C) then treated with water (0.24 parts) which reduced the reflux temperature to 107 C. A soft phase monomer mix containing butyl acrylate (76.56 parts), tert-butylaminoethyl-methacrylate (3.44 parts), 75%`tert-butyl peracetate (0.054 parts) and toluene (3.52 parts) is fed at a constant rate over the next 100 minutes. During the addition, the reaction temperature increases from 107 to -129 C. The reaction mixture is held at reflux for 15 minutes and then treated with a solution of 75% tert-butyl peracetate (0.054 parts) and toluene (2.84 parts) which is added at a uniform rate over 60 minutes. The mixture is held for 15 minutes at reflux, diluted with toluene (23.9 parts) and the water removed as a toluene azeotrope.
Toluene (40.85 parts) is used to dilute the polymer which is present as a 55.3% solution (100% conversion) with a ~ ;
Brookfield Viscosity of 33,000 cps. The product is con-centrated with a flask evaporator at 175 C. and 3-5 torr is a nominally 100% solids, highly viscous liquid with a viscosity of 13,200 cps (Brookfield NBT Viscometer, spindle 27, 20 rpm at 177C.).

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Examples IX through XIX of I`able VI are prepared by substantially the process of Example VIII. With the exception of Example XIX, the composition of the hard and soft phases is as in Example VIII. The Examples differ in the amount of hard phase and/or the molecular weight of the hard of soft phase. The molecular weight of the hard phase is altered by changingthe initiator level; the molecular weight of the soft phase is controlled by adjusting the polymerization temperature with added water: (1) with no water (Condition A) the polymerization temperature ranged from 117 -139 C.; :
(2) with 0.24 parts of water per lO0 parts total monomer added prior to the start of the soft phase monomer addition (Condition B) the polymerization temperature ranged from 105 -130C.; (3) with water added as in Condition B and then when-ever the polymerization temperature rises to 115C, 0.08 parts of water are added (Condition C).

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EX~MPLE XX - Sequential Polymerization - Water Added to First CopolYmerization.-A flask containing toluene (76.0 g.), isobutylmethacrylate (51.4 g.) and methacrylic acid (1.96 g.) is heated to 105C. and treated with toluene (5.0 g.~ and tert-butyl peroctoate (0.85 g.). The reaction mixture is brought to reflux (1]5C.) and held there for l5 minutes.
Water (4.0 ml.) is added to decrease the reflux temperature to 100C. A solution of toluene (5.0 g.), isobutyl methacrylate (217.0 g.), methacrylic acid (8.3 g.) and tert-butyl peroctoate (3.6 g.) is then added at a uniform rate over a 45 minute period. The final temperature is 110C.
More toluene (10 g.) is added. The reaction mixture is ~-maintained at reflux for an additional 15 minutes and then treated over a 30 minute period with a solution of toluene ~
(8.6 g.) and tert-butyl peroctoate (0.48 g.). The reaction ~ ~-mixture is then refluxed for 15 minutes at 106C. A soft phase monomer mix prepared from toluene (87.0 g.), butyl acrylate (1067.0 g.), tert-butylaminoethyl methacrylate (48 g.) and tert-butyl peracetate (0.75 g.; 75%) is fed at a constant rate over a 100 minute period. During this addition, the reflux temperature increases to 130C.
Toluene (10 g.) is added. Reflux is maintained for 15 minutes and then a catalyst solution of tert-butyl peracetate (3.0 g.; 75%) in toluene (28.6 g.) is added at a constant rate over a 60 minute period. The reaction mixture is refluxed for an additional 15 minutes and then water -(3 ml.) and toluene (19.6 g.) are removed by azeotropic ;~
distillation. The final solids of 86.5% indicates 100%
conversion of monomers. The solvent is removed with a flash-evaporator at 175C. at 3 to 5 torr. to a nominally 100%
solids liquid with a viscosity of 16,600 cps (Brookfield NBT
Viscometer, Spindle 27, 20 rpm at 177C.).

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Claims

WHAT IS CLAIMED IS:

1. A composition comprising a blend or sequential polymerization of:
(A) from about 5 to about 95 parts by weight of an addition copolymer having a Tg in the range of from 0°
to -85°C. comprising:
(1) from about 85 to 99.5 parts by weight of a monomer or monomers selected from alkyl (C2 18) or alkoxyalkyl acrylate and (2) from about 0.5 to about 15 parts by weight of an ethylenically unsaturated amine, carboxylic acid or sulfonic acid or mixtures thereof with (B) from about 5 to about 95 parts by weight of an addition copolymer having a Tg in the range of from about 20° to about 150°C. comprising:
(1) from about 85 to about 99.5 parts by weight of a monomer or monomers selected from a monomer of the formula:

wherein R is hydrogen or methyl and R1 is lower alkyl, lower cycloalkyl or isobornyl and (2) from about 0.5 to about 15 parts by weight of an ethylenically unsaturated amine, carboxylic acid or sulfonic acid or mixtures thereof.

2. The composition of Claim 1 comprising a blend of or sequential polymerization of:
(A) from about 35 to about 90 parts by weight of a copolymer having a Tg in the range of from about -20°
to about -65°C. comprising:
(1) from about 88 to about 98.5 parts by weight of an alkyl acrylate and (2) from about 1.5 to about 12 parts by weight of an ethylenically unsaturated carboxylic acid or amine with (B) from about 10 to about 65 parts by weight of a copolymer having a Tg of 35°C. or more such as a Tg in the range of from about 35° to about 110°C. comprising:
(1) from about 88 to about 98.5 parts by weight of a monomer of the formula:

wherein R is hydrogen or methyl and R1 is lower alkyl, lower cycloalkyl or isobornyl and (2) from about 1.5 to about 12 parts by weight of an ethylenically unsaturated carboxylic acid or amine.

3. The composition of Claim 1 wherein the ethylenically unsaturated carboxylic acid, sulfonic acid or amine has the formula:

wherein R2 is hydrogen, methyl or carboxy and X is mono- or di-lower alkylamino lower alkoxy carbonyl, sulfo lower alkoxy carbonyl, a 5- or 6-membered heterocyclic amine radical, hydroxycarbonyl lower alkyl or lower alkoxy carbonylmethyl.

4. The composition of Claim 3 wherein the carboxylic acid, sulfonic acid or amine is selected from acrylic acid, methacrylic acid, itaconic acid and ?-alkyl esters thereof, 2-sulfoethyl methacrylate, tert-butylaminoethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, 2-vinylpyridine, 4-vinylpyridine, dimethylaminoethyl acrylate, diethylaminoethyl acrylate or 2-vinylquinoline.

5. The composition of Claim 4 comprising a blend of:
(A) from about 60 to about 85 parts by weight of a copolymer comprising:
(1) from about 94 to 98 parts by weight of a monomer selected from butylacrylate, 2-ethylhexyl acrylate, methylacrylate, ethyl acrylate, isobutyl acrylate, isoamyl acrylate or n-propyl acrylate and (2) from about 2 to about 6 parts by weight of dimethylaminoethyl acrylate and methacrylate, diethylaminoethyl acrylate and methacrylate or tert-butylaminoethyl methacrylate with (B) from about 15 to about 40 parts by weight of a copolymer comprising:
(1) from about 94 to 98 parts by weight of isobutyl methacrylate and isobornyl acrylate, isobornyl methacrylate, methyl methacrylates and (2) from about 2 to about 6 parts by weight of an acid selected from methacrylic acid, acrylic acid or itaconic acid.

6. The composition of Claim 5 for use as a pressure sensitive adhesive which comprises a blend of from about 70 to about 85 parts by weight of copolymer A and from about 15 to about 30 parts by weight of copolymer B.

7. The composition of Claim 6 comprising from 70 to 85 parts by weight of a copolymer comprising 95.7 parts by weight of butyl acrylate and 4.3 parts by weight of tert-butylaminoethyl acrylate with from 15 to 30 parts by weight of a copolymer of 96.3 parts by weight of isobutyl methacrylate and 3.7 parts by weight of methacrylic acid.

8. The composition of Claim 7 wherein the ratio of the copolymer of isobutyl methacrylate and methacrylic acid to the copolymer of butyl acrylate and tert butylaminoethyl acrylate is 82 to 18.