Process for producing a polymer emulsion

A polymer emulsion is produced by the free radical polymerization of a monomer having an ethylenic unsaturated double bond in the presence of 0.1 to 10 wt parts of a compound having the formula ##STR1## wherein R.sub.1 represents hydrogen atom or methyl group; R.sub.2 represents hydrogen atom, methyl or ethyl group; R.sub.3 represents an alkyl group having 6 to 22 carbon atoms; n is 1, 2, or 3; and X represents a halogen atom, per 100 wt parts of the monomer.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a process for producing a cationic polymer 
emulsion. More particularly, it relates to a process for producing a 
cationic emulsion of polymer which has both mechanical and chemical 
stability. 
2. Description of the Prior Art 
In the manufacture of synthetic rubbers, synthetic resins and paints, 
aqueous emulsion polymerization using an emulsifier has been employed to 
produce the polymer. The conventional emulsifiers used, however, have 
deleterious effects on the properties of the latex or polymer produced. 
Further, the conventional emulsifiers can cause difficulties. Recently, 
pollution caused by the conventional emulsifiers has become a problem. 
Conventional emulsifiers are found in the waste water from the washing and 
filtering steps of the process for producing a polymer by emulsion 
polymerization, and the discharged waste water is a source of water 
pollution. In addition, the emulsifier that remains in the polymer causes 
the polymer to adhere on mixing rolls and molds. 
In preparing adhesive compositions, it is necessary to use emulsion-type 
adhesive compositions instead of solvent-type adhesive compositions 
because of the air pollution caused by the solvents in solvent-based 
adhesive compositions. Unfortunately, the conventional emulsifiers have 
the effect of lowering the adhesive property of the emulsion. It has been 
theorized that these difficulties are caused by the bonding of the 
conventional emulsifiers through physical adsorption on the polymer 
particles in the emulsion. It is known that conventional emulsifiers can 
be removed from the polymer particles when heat or pressure is applied to 
them. 
It has been proposed to produce polymer emulsions by using an unsaturated 
acid or a reactive emulsifier without using the conventional emulsifiers 
(Japanese Unexamined Patent Publication Nos. 34588/1974 and 40388/1974). 
However, there is no disclosure in the prior art for producing a cationic 
polymer emulsion. 
Accordingly, there exists a need for a process which can prepare cationic 
polymer emulsions without using conventional emulsifiers. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a process for the 
production of a cationic polymer emulsion having mechanical and chemical 
stability without using conventional cationic emulsifiers. Polymer 
emulsion means aqueous emulsions of homopolymers or copolymers of a 
monomer having an ethylenically unsaturated double bond. 
This and other objects of the present invention have been attained by 
producing a cationic polymer emulsion by free radical polymerization of a 
monomer having an ethylenically unsaturated double bond in the presence of 
0.1 to 10 wt parts, preferably 2 to 5 wt parts of a compound having the 
formula 
##STR2## 
wherein R.sub.1 represents hydrogen atom or methyl group; R.sub.2 
represents hydrogen atom, methyl or ethyl group; R.sub.3 represents an 
alkyl group having 6 to 22 carbon atoms; n is 1, 2 or 3; and X represents 
a halogen atom, per 100 wt parts of the monomer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The compounds having the above formula can be produced by reacting a 
primary, secondary or tertiary amine having a C.sub.6-22 alkyl group with 
an alkyl halide such as allyl chloride, methallyl chloride, allyl bromide 
and the like. Typical componds having the formula include 
allyldodecylammonium chloride, methallyltridecylammonium chloride, 
diallyldodecylammonium chloride, triallyldodecylammonium bromide, 
allyldimethyloctylammonium chloride, methallyldimethyloctadecylammonium 
chloride, methallyldimethylcoconutalkylammonium bromide, 
allyldimethyldodecylammonium chloride, diallylmethylhexylammonium 
chloride, and the like. The reactive emulsifier can be used by itself, or 
used together with a conventional cationic emulsifer such as 
dodecyltrimethylammonium chloride, coconutalkyltrimethylammonium chloride, 
coconutalkyldimethylbenzylammonium chloride, dodecylpyridinum chloride and 
the like. 
The monomers having an ethylenically unsaturated double bond used in this 
invention include dienes such as 1-chlorobutadiene, 2,3-dichlorobutadiene, 
2-cyanobutadiene, isoprene, chloroprene, etc. and ethylene, styrene, vinyl 
chloride, vinyl acetate, vinyl pyridine, acrylonitrile, acrylates and 
methacrylates, and mixtures thereof. 
Known free radical initiators can be used in the process of this invention; 
2,2' azobisisobutylamidine hydrochloride having a cationic terminal group 
is especially preferable. It is also possible to use mixtures of 
hydroperoxide and amines or other known redox-type catalysts, as the 
initiator. 
It is possible to use conventional molecular weight modifiers which have 
been previously used in emulsion polymerization. Typical molecular weight 
modifiers include alkylmercaptans, alkylxanthogendisulfides, 
halohydrocarbons and the like. It is also possible to add a polyfunctional 
monomer such as divinylbenzene, glycidylmethacrylate, etc., in order to 
form a gel. The amount of the additives can be selected as desired to 
control the molecular weight and gelation. 
The polymerization can be conducted at 0.degree. to 100.degree. C, 
preferably 10.degree. to 80.degree. C. The pH of the polymerization system 
can be in the broad range of acidic to alkaline pH, but is preferably in 
the range of neutral to acidic pH. 
The polymerization can be stopped by adding a conventional polymerization 
inhibitor such as hydroquinone, t-butyl catechol, phenothiazine, etc. When 
unreacted monomer remains, it can be removed by treating the 
polymerization mixture at an elevated temperature under reduced pressure. 
Having generally described the invention, a more complete understanding can 
be obtained by reference to certain specific examples, which are included 
for purposes of illustration only and are not intended to be limiting 
unless otherwise specified. 
In the examples, the term "part" designates "part by weight" unless 
otherwise defined. 
EXAMPLES 1 to 2 
The polymerization was conducted in a four necked flask equipped with a 
stirrer, a condenser and a temperature detecting device in a nitrogen 
atomsphere. Allyl dimethylcoconutalkylammonium chloride was dissolved in 
130 parts of water at the ratio set forth in Table 1. A mixture of 0.25 wt 
part of n-dodecylmercaptan and 100 parts of chloroprene was added to the 
aqueous solution with stirring. When it reached 40.degree. C, 0.5 parts of 
2,2'-azobisisobutylamidinum chloride as a polymerization initiator was 
added to initiate the polymerization. When the conversion reached 80%, the 
polymerization was stopped by adding hydroquinone. After the addition of 
hydroquinone, the unreacted monomer was removed by the conventional 
stripping method. As shown in Table 1, no aggregate was formed and the 
resulting emulsion has high stability after the polymerization. Even 
though methanol was added to the emulsion, no aggregate was formed 
demonstrating high chemical stability. 
TABLE 1 
______________________________________ 
Allyldimethyl Time for Surface 
coconutalkyl polymeri- 
tension 
Aggregate 
Example 
ammonium chloride 
zation (d/cm) (g) 
______________________________________ 
1 2 240 41.6 0 
2 4 180 36.6 0 
______________________________________ 
EXAMPLES 3 to 9 
In the apparatus of Example 1, the polymerization of Example 1 was repeated 
except using 4.0 parts of the reactive emulsifier instead of 2.0 parts of 
allyldimethylcoconutalkylammonium chloride, and the polymerization was 
stopped and the unreacted monomer was distilled out. As shown in Table 2, 
no aggregate was found after the polymerization. 
TABLE 2 
______________________________________ 
Time for 
polymeri- 
Surface 
Ex. zation tension 
Aggregate 
No. Reactive emulsifier 
(min) (d/cm) (g) 
______________________________________ 
3 allyldimethylcoconut- 
185 36.3 none 
alkylammonium 
bromide 
4 methacryldimethylcoco- 
180 37.4 none 
nutalkylammonium 
chloride 
5 allyldimethyldodecyl- 
170 34.2 none 
ammonium chloride 
6 methallyldimethyl- 
195 35.2 none 
tetradecylammonium 
chloride 
7 allyldimethyl- 180 36.7 none 
octadecylammonium 
chloride 
8 diallyldodecyl- 195 38.8 none 
ammonium chloride 
9 triallyloctyl- 210 39.6 none 
ammonium chloride 
______________________________________ 
The surface tension of the emulsion was satisfactorily low so that the 
resulting emulsion was stable and had as high chemical stability as that 
of Example 1. 
EXAMPLES 10 to 12 
In the process of Example 7, 100 parts of the monomer shown in Table 3 was 
used instead of 100 parts of chloroprene and the emulsions were produced. 
The surface tension of the emulsion was statisfactorily low so that the 
resulting emulsion was stable and had as high a chemical stability as that 
of Example 1. 
TABLE 3 
______________________________________ 
Time for 
polymeri- 
Surface 
Example zation tension 
No. Monomer (min) (d/cm) Aggregate 
______________________________________ 
10 styrene 485 33.5 none 
11 methyl methacrylate 
510 37.2 none 
12 vinyl acetate 360 34.3 none 
______________________________________ 
EXAMPLE 13 
A stainless steel autoclave equipped with an electromagnetic stirrer and a 
pressure gauge was purged with nitrogen and was kept in a reduced 
pressure. 130 Parts of water, 3.0 parts of 
allyldimethylcoconutalkylammonium chloride, 0.3 part of n-dodecylmercaptan 
and 100 parts of butadiene were charged into the autoclave. When the 
temperature reached 40.degree. C, 1.0 part of 2,2'-azobisisobutylamidine 
chloride were added to initate the polymerization. The mixture was heated 
for 8 hours to polymerize it to a conversion of 73%. The unreacted monomer 
was removed by the conventional stripping method. No aggregate was found 
and the resulting emulsion was stable. The surface tension of the emulsion 
was satisfactorily low, 37.1 d/cm, so as to be stable and the resulting 
emulsion had as high a chemical stability as that of Example 1. 
EXAMPLE 14 
In the process of Example 5, a mixture of 90 parts of chloroprene and 10 
parts of 2,3-dichlorobutadiene were used instead of 100 parts of 
chloroprene and the emulsion was produced. No aggregate was found and the 
resulting emulsion was stable. The surface tension of the emulsion was 
satisfactorily low, 34.5 d/cm, so as to be stable and the resulting 
emulsion had high chemical stability. 
EXAMPLE 15 
In the process of Example 14, styrene was used instead of 
2,3-dichlorobutadiene and the emulsion was produced. No aggregate was 
found and the resulting emulsion was stable. The surface tension of the 
emulsion was satisfactorily low, 34.2 d/cm, so as to be stable. Even 
though methanol was added to the emulsion, no aggregate was formed, thus 
demonstrating the high chemical stability of the emulsion. 
Having now fully described the invention, it will be apparent to one of 
ordinary skill in the art that many changes and modifications can be made 
thereto without departing from the spirit or scope of the invention as set 
forth herein.