CA1327672C - Continuous method of treating polymer reaction mixture - Google Patents
Continuous method of treating polymer reaction mixtureInfo
- Publication number
- CA1327672C CA1327672C CA000552736A CA552736A CA1327672C CA 1327672 C CA1327672 C CA 1327672C CA 000552736 A CA000552736 A CA 000552736A CA 552736 A CA552736 A CA 552736A CA 1327672 C CA1327672 C CA 1327672C
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- CA
- Canada
- Prior art keywords
- polymer
- molecular weight
- reaction mixture
- heat
- styrene polymer
- Prior art date
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Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G9/00—Developers
- G03G9/08—Developers with toner particles
- G03G9/087—Binders for toner particles
- G03G9/08702—Binders for toner particles comprising macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- G03G9/08706—Polymers of alkenyl-aromatic compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F6/00—Post-polymerisation treatments
- C08F6/06—Treatment of polymer solutions
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- Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Spectroscopy & Molecular Physics (AREA)
- General Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Developing Agents For Electrophotography (AREA)
Abstract
ABSTRACT
A continuous method of treating a polymer reaction mixture for continuously separating a styrene polymer and volatile ingredient by flowing down, for example, a mixture of low molecular weight styrene polymer and high molecular weight styrene polymer through a circular-ring-shaped space formed between a jacketed double pipe and a concentrically located inner pipe of a heat-exchanger, and flashing into a vacuum chamber connected with said heat-exchanger, is provided.
The polymer is useful for the preparation of electrophotographic toner.
A continuous method of treating a polymer reaction mixture for continuously separating a styrene polymer and volatile ingredient by flowing down, for example, a mixture of low molecular weight styrene polymer and high molecular weight styrene polymer through a circular-ring-shaped space formed between a jacketed double pipe and a concentrically located inner pipe of a heat-exchanger, and flashing into a vacuum chamber connected with said heat-exchanger, is provided.
The polymer is useful for the preparation of electrophotographic toner.
Description
1327~72 SPECIFICATION
Title of the Invention .
Continuous Method of Treating Polymer Reaction Mixture Background of the Invention 1. Fie]Ld of the Invention The present invention relates to a method for separating a styrene polymer useful in the field of electrophotographic toner by continuously treating a reac~ion mixture containing the styrene polymer prepared by the homopolymerization of styrene monomer or its coPolymerization with other vinyl monomer to separate and remove volatile ingredients such as unreacted monomer, polymerization solvent and ~ `
decomposition product of polymerization initiator by use of a specific separation equipment of the volatile ingredients.
Title of the Invention .
Continuous Method of Treating Polymer Reaction Mixture Background of the Invention 1. Fie]Ld of the Invention The present invention relates to a method for separating a styrene polymer useful in the field of electrophotographic toner by continuously treating a reac~ion mixture containing the styrene polymer prepared by the homopolymerization of styrene monomer or its coPolymerization with other vinyl monomer to separate and remove volatile ingredients such as unreacted monomer, polymerization solvent and ~ `
decomposition product of polymerization initiator by use of a specific separation equipment of the volatile ingredients.
2. Descr~iPtion of the Prior Art Methods ~or separating the bulk- or solution- :
polymerized styrene polymer from the reaction mixture have been disclosecl in Japanese Patent Publication Nosu 31678/1970, 29797/]L973 etc. The styrene polymer I described in these publications has a relatively high ~.
.. . .
:,:
1327~72 .
molecular weight in order to use, for example, for molding application. These methods have a dis-advantage and not suitable for treating the reaction mixture containing the styr~ne polymer of this -invention.
For example, Japanese Patent Publication No. 29797/1973 discloses a method for using a vertical multitubular heat-exchanger~ In the case, however, of applying the heat-exchanger for the reaction mixture of styrene polymer in this invention, flow rate oi- the reaction mixture into the heating zone is remarkably increased. This is because the low molecular weight polymer always existing in the aforesaid reaction mixture is foamed by the reduced 15 pressure in the heat exchanger. Therefore the flow -! line of reaction mixture still maintains its original direction after flowing into the heating zone, and ' the distribution oi. i--low amount to each tube ~ends to be uneven in the heating zone. This phenomenon results in variation of flow amount, flow amount distribution and resiàence time in the heating zone. Consequently the efficiency for removing the volatile ingredients is found to have a remarkable fluctuation and the -~
quality of product is greatly damaged. It is of course possible to homogenize the flow amount distribution to some extent by fitting a dispersion plàte at the 1327~72 inlet of heating zone. It, however, is still unsatisfactory so long as the vertical multitubular heat-exchanger is used.
Disclosure of the Invention An object of an aspect of this .Invention is to provide a method for continuously separating a styrene polymer containing a very small amount of a volatile ingr~dient by homogeneously flowing a reaction mixture o~ the styrene polymer containing a low molecular weight lo polymer into a heating zone of a heat-exchanger and removing the volatile ingredient from the reaction mixture under uniform conditions.
An aspect of the invention is as follows: -A continuous method of treating a polymer reaction ~ixture for separating a styrene polymer to be used for electrophotographic toner by continuously removing volatile ingredient from a reaction mixture containing the styrene polymer obtained by polymerizing styrene .
mono~er alone or with other vinyl monomer, which . 20 co~pri~es flowing doun and preheating the reaction mixture containing said styrene polymer through a circular-ring-shaped space of a heat-exchanger, said heat-exchanger consisting of an outer double pipe as a ~acket of circulating heat medium, a concentrically located inner pipe of the heat-exchanger for circulating the ~eat medium and the circular-ring-shaped space formed in between, and flashing the reaction mixture containing said styrene polymer into a vacuum chamber connected uith said heat-exchanger to continuously sQparate the styrene polymer and the volatile ingredient; wherein the reaction mixture at least contains a low molecular weight polymer having a number ~:
~verage molecular weight of 1,000 - 5,000 and a glass transition te~pera,ture of 40 - 80C.
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1327~72 - 4 - :
-. Brief Description of the Drawings . Figure 1 is a vertical section illustrating an embodiment of equipment suitable for use in this ~` invention.
Figure 2 is a section along the line A-A' in Figure 1.
In these Figures, 1 is inlet valve, 2 is head of heat-exchanger, 3 is intermediate flange, 4 is heat exchange jacket, 5 is vacuum chamber, 6 is condenser, 7 is discharge pump, 8 is tube in the inner pipe of heat-exchanger, 9 is inner pipe of heat-exchanger, 10 is circular-ring-shaped space, 11 is inside wall of hea~-exchanger, 12 is dispersed fluid, 13 is outlet fluid, 14 is valatile gas, 15 is . copolymer, 16 is heat medium inlet to inner pipe, 17 - 19 is heat medium flow line in inner pipe, 20 is heat medium outlet of inner pipe, 21 is heat medium inlet, 22 is heat medium outlet, 23 is vacuum chamber jacket, and 2~ is outside wall of heat-exchanger jacket.
~ . ' Preferred Embodiments of the Invention The method of this invention can of course be applied for continuously treating the reaction :
1327~72 mixture of styrene polymer polymerized by a batch process and separating the polymer. By combining - with such a process that disclosed, for example, in Japanese Patent Laid-open No. 125481/1976, the method of this invention can provide an extremely effective process for continuously preparing the styrene polymer `- containing a low molecular weight polymer.
~` The styrene polymer which is the object of this invention includes the low molecular weight polymer having a number average molecular weight of 1,000 - 5,000 and a glass transition temperature ranging 40 - 80C, a styrene polymer consisting of 70 - 30 parts of above low molecular weight polymer and 30 - 70 parts of a high molecular weight polymer, and a mixture of above styrene polymer with a low molecular weight polyalefins.
¦ The monomer which constitutes so-called styrene polymer of this invention includes styrene and other vinyl monomar. The examples of other vinyl monomer which may be used include o-methyl styrene, m-methyl ~tyrene, p-methyl styrene, ~-methyl styrene, p-t-butyl styrene, vinyl naphthalene, vinyl chloride, vinyl fluoride, vinyl acetate, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, methyl acrylate, ethyl acrylate, -~t ", . ,,, , , ,,, " ,, , ~"~ ,, ,,j "" ~"~ , ",,, ,, " J ""- ,; ~ ~ " " : " ~ ", -`~ 1327~72 n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, dimethyl fumarate, di-i-propyl fumarate, di-n-butyl fumarate, di-i-butyl fumarate, dimethyl maleate, diethyl maleate, di-i-propyl maleate, di-n-butyl maleate~ di-i-butyl maleate, 2-vinyl-pyridine, 2-vinylpyrrole, N-vinylcarbazole, N-vinylindole and N-vinylpyrrolidone. At least one of these monomers can be copolymerized with styrene. In the practice of this invention, styrene alone or a mixture of styrene with methacrylic acid and/or methyl methacrylate is particularly preferred among these vinyl monomers.
Besides in this invention, a homogeneous mixture of polymer can also be prepared effectively by uniformly mixing other high molecular weight styrene polymer with the reaction mixture of low molecular weight polymer prior to applying the method of this invention. Furthermore the resulting mixture can also be added with at least one of the low molecular ; 25 weight polyoleffins such as low molecular weight ~ polypropylene, polyethylene wax, polytetrafluoroethylene :i .' ' ': .
1327~72 and the like to obtain a uniform mixture.
ccording to the method of this invention, the volatile ingredients can be eontinuously removed from the reaction mixture of styrene polymer containing the low molecular weight polymer, which was difficult to perform by the prior art. The volatile content of i aforesaid styrene polymer can always be reduced to ~ 0.3~ or less without remarkable variation in the d~ efficiency for removing the volatile ingredients. In ~ .
addition, such low content of volatile matter in the aforesaid styrene polymer can provide electrophoto~
~a graphic toner which is excellent in blocking resistance, offset resistance and electrostatic charge and is very valuable in the actual use.
The eguipment for separating the volatile ingredients in this invention includes, for example, that illustrated in Figures 1 and 2 which is disclosed -in Japanese Patent Laid-open No. 24411/1981. The subject to be treated in this disclosure is a reactive 20 mixture of polymer. The reactive polymer causes a ~"
crosslink`ing reaction by heating in the treatment and generated gel adheres to the pipe. Therefore the -~
object of eguipment; in above disclosure is to prevent blockage of pipes in the heat-exchanger. On the other hand, the subject of this invention to be treated is a reaction mixture of styrene polymer containing the ' ,.': ., .' ','; '' .
~ low molecular weight polymer and causes no gelling -~ reaction when heated. In addition, the object of using this equipment in this invention is to uniformly flow the reaction mixture into the heating zone of the heat-exchanger, remove the vola~ile ingredients ~ from the reaction mixture under uniform conditions ¦ and continuously prepare the low molecular weight styrene polymer having a very low content of the ' volatile ingredients. As mentioned above, the present invention is quite different from aforesaid disclosure in the subject and object of treatment.
A preferred example for continuously treating the reaction mixture in this invention will ~ -be illustrated as follows.
That is, vinyl polymer is carried out a bulk polymerization at 60 - 150C to a polymerization ratio of 30 - 90% by weight, successively added with a solvent to reduce viscosity of the reaction mixture and conducted a solution polymerization to obtain the high molecular weight polymer. A styrene type vinyl monomer is separately polymerized at a temperature of 190 - 230C in a state of solution to obtain the low molecular weight polymer.
~ ~ mixture is prepared from 30 - 70 parts `~25 by weight of the high molecular weight polymer as solid ~and 70 - 30 parts by weight of the low molecular weight , 1327~72 g polymer as solid.
`; Then the resulting mixture of polymer solu-~` tion is continuously treated by the method of this ~^ invention to separate the volatile ingredients from the styrene polymer. The resulting styrene polymer has a number average molecular weight (Mn) of 2,000 -15~000, a Z average molecular weight (Mz1 of not less than 400,000 and Mz/Mn of 50 - 600, and is suitable for the preparation of toner resin.
The present invention will hereinafter be illustrated with respect to examples. Unless otherwise indic~ted, part means part by weight.
Example 1 A reactor was charged with 70 parts of styrene and 30 parts of 1:1 solvent mixture of xylene and ethyl benzene and maintained at 210C. Polymer- `~
ization reaction was conducted by continuously feeding an uniform solution containing 0.5 mole of di-t-butyl ~ `
20 peroxide per 100 moles of styrene into the~reactor ;`
~ at a rate`of 750 cc/hr under the internal pressure -~
¦ of 6 kg/cm2. The resulting reaction mixture containing the low molecular weight polymer was charged at the same rate as above from the outlet of reactor through the inlet valve of volatile matter separation equipment to the circular-ring-shaped space of heat-exchanger.
: . .
'. ,.
;~' ,.. .
1327~72 The volatile matter separation equipment is illustrated in Figures 1 and 2. The equipment has outer double pipe for additional use as a jacket of circulating heat medium, concentrically located inner pipe of the 5 h~at exchanger for cir~ulating the heat medium and the circular-ring-shaped space formed between the outer and inner pipes. The heat medium was circulated the jacket and inner pipe at 210C. The temperature was 210C at the outlet of reactor and reduced to 190C
10 at the inside of heat-exchanger head by the foaming due to reduced pressure and latent heat of vaporization.
The reaction mixture was discharged into the vacuum chamber ; maintained at an absolute pressure of 20 mmHg and 3 a jacket temperature of 140C. The mixture wa~ separated 15 into gas and liquid phases by flashing and the liquid phase was collected in the bottom of chamber. The low molecular weight polymer had a temperature of 140C
after separating the volatile ingredients. The resulting polystyrene was continuously discharged from the 20 bottom of vacuum chamber and had a number average mo~ecular weight of 2,500, a glass transition tempera-! ture of 64C and a nonvolatile content of 99.9%.
The number average molecular weight was measured in accorda~nce with gel permeation chromatography ` ~ `
25 using polystyrene clS standard. The glass transition i temperature was measured according to DSC method. The - 13~72 non-volatile content is measured by precisely weighing the sample in a dish, heating it at 105C for 90 minutes and weighing the residual weight to calculate the loss. The same methods of analyses were also used -~ 5 in tne following Examples and Comparative Examples.
~3 .
Comparative Example 1 The reaction mixture of Example 1 containing ~ the low molecular weight polymer was heated by using a .3 10 multitubular heat-exchanger having the pipe outlet directly connecting with the vacuum chamber. The flowing down state of the polymer at the outlet of each pipe in the heat-exchanger was observed from the window equipped on tha vacuum chamber. The flow rate from each pipe was unstable and the non-volatile content of discharged polystyrene was reduced to :
8.9~.
Comparative Example 2 T~e procedures of Example 1 were repeated by using the same reaction mixture containing the low molecular weight polymer and employing the same heat exchanger having the same area of flow line and the same area of heat transmission except the circulation of heat medium through the inner pipe was omitted (that is, used as a hollow pipe). The non-volatile , .
;.'':
content of discharged polystyrene was reduced to 99.2~.
Example 2 The reaction mixture of Example 1 containing 5 the low molecular weight polymer was used as the first component. A high molecular weight styrene polymer derived from 70 parts of styrene and 30 parts of n-butyl acrylate and having a weight average molecular weight of 300,000 and a glass transition temperature 10 of 58C was used as the second component. The first and second components were respectively dissolved in xylene. Both xylene solutions were uniformly mixed in amounts to give a 50:50 weight ratio of the low molecular weight and high molecular weight polymers.
15 Thereafter the same procedures as in Example 1 were carried out by using the same volatile matter separation equipment. The resulting styrene polymer 3 was a homogeneous mixture of the high molecular weight T and low molecul~r weight polymers and had a non-20 volatile content of 99~8%.
Example 3 The reaction mixture of Example 1 containing `
the low molecular weight polymer was add with 5~ by 25 weight of low molecular weight polypropylene and unifonmly mixed. Thereafter the same procedures as `.
,, .~ .
1327~72 in Example 1 was carried out. The low molecular weight ' styrene polymer obtained was a homogeneous mixture with the low molecular weight polypropylene and had a non-volatile content of 99.9~.
` 5 i Example 4 Styrene methacrylic acid copolymer was prepared by using the same procedures as in Example 1 except 67 parts of styrene and 3 parts of methacrylic ~ 10 acid was used in place of 70 parts of styrene. The 3 resulting copolymer had a number average molecular ~ ~
weight of 3,800, a glass transition temperature of ~ ~`
70C, and a non-volatile content of 99.8%.
.:
15 Example 5 ~ `
I A nitrogen replaced flask was charged with ~ -72 parts of styrene and 28 parts of butyl acrylate as vinyl polymers, and heated to 12nC. Bulk polymerization was conducted for 10 hours at this temperature to `
20 obtain a conversion of 55~. Successively 30 parts of i xy]Lene wère added to prepare a solution. A mixture containing 0.1 part ~f dibutyl peroxide dissolved in 50 parts of xylene was continuously add to the solution I over 8 hours at 130C. The reaction was continuad for 25 an hour after completing the addition. The resulting j high molecular weight polymer was named A-l.
'.,'..
1327~72 ; - 14 -In the next step, solution polymerization was conducted by continuously adding a homogeneous solution of O.S mole of di-t-butyl peroxide in 100 moles of styrene at a rate of 750 cc/hr to the mixture consisting of 70 parts of styrene and 30 parts of a solvent mixture containing xylene and ethyl benzene.
The reaction conditions maintained were an internal reactor temperature of 210C, the internal pressure of 6 kg/cm2 and an outlet temperature of 100C.
The resulting low molecular weight styrene polymer had a conversion of 99.5% by weight. The t mole~ular weight was measured in accordance with gel t permeation chromatography by using monodispersed standard polystyrene as a reference sample and tetra-; 15 hydrofuran as an eluent. The number average molecular weight thus obtained was 2,100. --Besides the solid polymer A-2 was obtained by separately removing ~he solvent and its glass transition temperature (Tg) was measured with a differential scanning calorimeter by using alumina as ref~rence. The Tg measured was 70C.
A mixture was prepared from 50 parts of above low molecular weight styrene polymer A-2 and 90 parts of the aforesaid high molecular weight polymer A-l (50 parts as solid). The solvent was removed from the mixture by employing the same volatile matter ::
,.
:.'~' . ' :
1327~72 separation equipment of Example 1 as illustrated in Figures 1 and 2. The mixture was heated to 200OC and flashed into a vacuum system maintained at 10 mmHg by using almost the same conditions as in Example 1.
The resulting polymer had Mn of 2,800, Mz of 652,000, Mz~Mn of 233 and Tg of 57C. In addition the polymer had a residual volatile content of 0.09~.
The styrene polymer thus obtained was evaluated the characteristics for the electrophotographic -toner.
(Preparation of the toner) ..
In a Henshel mixer, 100 parts of the resin, 10 parts of carbon black (MA-100: a product of Mitsubishi Chemical Co.) as a coloring agent, 3 parts of poly-propylene wax and 0.5 - 2 parts of Spiron Black TRH as a charge regulator were mixed. The mixture was hot-~neaded with a twin screw extruder at a temperature of 140C (inlet) - 150C (outlet), cooled and crushed.
The resulting coarse particles were finely ground with a jet mill and subjected to air classification to obtain the toner having a particle size of 8 - 20 ~m [ll.S ~m in average). The resulting toner was mixed with 0.15 part of colloidal silica in Henshel mixer and tested.
The amount of charge controlling agent was '` '' ~ .
` 1327~72 controlled to obtain -15 ~C/g of electrostatic charge - after mixing 95 parts of the carrier for EP870 with 5 parts of the toner in a V-blender for 30 minutes.
~Evaluation as the Toner) Furthermore duplication characteristics were measure~ under the following conditions by Electro-photographic Copying Machine EP870 (a product from Minolta Camera Co.) equipped with Teflon hot-rolls.
Fixing ability: TM
A plastic eraser "NONO" (a product from Tombo Pencil Co.) was gone back and forth 20 times j with a constant force between a solid black part and a non-tonered white part on a duplicated sheet.
Toner removal from the black part and soil of the white part were observed and divided into the following four classes.
......... ....... No toner removal at all.
......... ....... Good.
~ ..... Toner was somewhat removed.
X ..... Poor. Toner was removed and caused much soil.
Contamination of the white background:
The white part of the 100th sheet was compared with that of the lO,OOOth sheet in a continuous copying operation. The degree of contamination on the ` ` 1327672 white background due to the scattering of toner was divided into the following three classes.
i ~- O ~.... Good, ... contamin~tion was observed with a magnifying glass having a magnification i of 30 times.
i~ X ...... Contamination was observed with the .~;
naked eye.
Offset resistance:
The offset refers to a phenomenon that a part of the toner is attached on the surface of a fixing roll and then transferred again onto the fresh surface of a paper after one rotation of the roll to cause the contamination of the paper.
O ... No contamination was found over 10,000 sheets of continuous copying operation.
X ... Contamination was found in the same ¦ conditions.
~ '`'`
Blo~cking resistance:
Blocking resistance was evaluated by observing the aggregation after allowing to stand the toner for 8 hours a~ the temperature of 55C under 80% relative humidity. Results were illustrated by the following four classes.
~.
"'.
: -..... . . ..
... No aggregation was found at all.
O ... Aggregation was found partially but easily unfastened.
~` ~ . . . Firm coagulate was founcl in part.
S X ...... Firm coagulate was found entirely.
,, .
Variation of electrostatic charge:
In the continuous copying operation, tribo-electrostatic charges of the 100th and lO,OOOth duplicates were expressed by the following ratio (absolute value).
?
(Amount of charge (Amount of charge after lO,OOOth - after 100th (Amount of charge after lOOtl~rpl-ica~te) x 100(%) `
,~' When the ratio was not more than 10(%), the 3 variation was considered good.
~Dispersibility of the coloring agent:
slide glass was put on a hot plate previou~ly heated at 250 - 300C and a small amount of the toner was placed on the slide glass. A cover gl~s was put on the toner sample simultaneously with the fusion of the toner and pressed with a given pressure for 60 seconds. The sample was taken out of the hot plate and allowed to cool. The dispersion of coloring agent was observed with an optical transmission microscope having a magnification of 400 - 1,000 times. ~`
", .;.:
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1327~72 .~ -- 1 9 .. .
The results of the observation was divided into the following two classes.
-`~ O ...... No undispersed or aggregated particles of ~- the coloring agent were found in any field of vision.
X ... Many undispersed or aggregated particles of the coloring agent were found.
Reproducibility of the completely solid black part:
Irregular gloss of the solid black part was observed on the 100th duplicate from the start of ; copying operation. The results were divided into the following three classes.
.~ .
¦ 15O ...... Irregulax gloss was slight.
~ ... Irregular gloss was found in some degree.
¦ `X ..... Irregulax gloss was remarkable.
- .
(Evaluation results as toner) . _ _ :
20 Fixing ability ~
. __ .__ _ ..
Contamination of the white background 1 Offset resistance O
_ __ ................................. _ Blocking resistance - O
. . . _ ': -Variation of electrostatic charge 5.2 -~' . . ............................................. , Dispersibility of the coloring agent O
., ~.~' . .
- .
polymerized styrene polymer from the reaction mixture have been disclosecl in Japanese Patent Publication Nosu 31678/1970, 29797/]L973 etc. The styrene polymer I described in these publications has a relatively high ~.
.. . .
:,:
1327~72 .
molecular weight in order to use, for example, for molding application. These methods have a dis-advantage and not suitable for treating the reaction mixture containing the styr~ne polymer of this -invention.
For example, Japanese Patent Publication No. 29797/1973 discloses a method for using a vertical multitubular heat-exchanger~ In the case, however, of applying the heat-exchanger for the reaction mixture of styrene polymer in this invention, flow rate oi- the reaction mixture into the heating zone is remarkably increased. This is because the low molecular weight polymer always existing in the aforesaid reaction mixture is foamed by the reduced 15 pressure in the heat exchanger. Therefore the flow -! line of reaction mixture still maintains its original direction after flowing into the heating zone, and ' the distribution oi. i--low amount to each tube ~ends to be uneven in the heating zone. This phenomenon results in variation of flow amount, flow amount distribution and resiàence time in the heating zone. Consequently the efficiency for removing the volatile ingredients is found to have a remarkable fluctuation and the -~
quality of product is greatly damaged. It is of course possible to homogenize the flow amount distribution to some extent by fitting a dispersion plàte at the 1327~72 inlet of heating zone. It, however, is still unsatisfactory so long as the vertical multitubular heat-exchanger is used.
Disclosure of the Invention An object of an aspect of this .Invention is to provide a method for continuously separating a styrene polymer containing a very small amount of a volatile ingr~dient by homogeneously flowing a reaction mixture o~ the styrene polymer containing a low molecular weight lo polymer into a heating zone of a heat-exchanger and removing the volatile ingredient from the reaction mixture under uniform conditions.
An aspect of the invention is as follows: -A continuous method of treating a polymer reaction ~ixture for separating a styrene polymer to be used for electrophotographic toner by continuously removing volatile ingredient from a reaction mixture containing the styrene polymer obtained by polymerizing styrene .
mono~er alone or with other vinyl monomer, which . 20 co~pri~es flowing doun and preheating the reaction mixture containing said styrene polymer through a circular-ring-shaped space of a heat-exchanger, said heat-exchanger consisting of an outer double pipe as a ~acket of circulating heat medium, a concentrically located inner pipe of the heat-exchanger for circulating the ~eat medium and the circular-ring-shaped space formed in between, and flashing the reaction mixture containing said styrene polymer into a vacuum chamber connected uith said heat-exchanger to continuously sQparate the styrene polymer and the volatile ingredient; wherein the reaction mixture at least contains a low molecular weight polymer having a number ~:
~verage molecular weight of 1,000 - 5,000 and a glass transition te~pera,ture of 40 - 80C.
'` B'l ~.
~ .
. . j ,- ., ~ - . . ;., . . - i . . . - : ; . - ;
`
1327~72 - 4 - :
-. Brief Description of the Drawings . Figure 1 is a vertical section illustrating an embodiment of equipment suitable for use in this ~` invention.
Figure 2 is a section along the line A-A' in Figure 1.
In these Figures, 1 is inlet valve, 2 is head of heat-exchanger, 3 is intermediate flange, 4 is heat exchange jacket, 5 is vacuum chamber, 6 is condenser, 7 is discharge pump, 8 is tube in the inner pipe of heat-exchanger, 9 is inner pipe of heat-exchanger, 10 is circular-ring-shaped space, 11 is inside wall of hea~-exchanger, 12 is dispersed fluid, 13 is outlet fluid, 14 is valatile gas, 15 is . copolymer, 16 is heat medium inlet to inner pipe, 17 - 19 is heat medium flow line in inner pipe, 20 is heat medium outlet of inner pipe, 21 is heat medium inlet, 22 is heat medium outlet, 23 is vacuum chamber jacket, and 2~ is outside wall of heat-exchanger jacket.
~ . ' Preferred Embodiments of the Invention The method of this invention can of course be applied for continuously treating the reaction :
1327~72 mixture of styrene polymer polymerized by a batch process and separating the polymer. By combining - with such a process that disclosed, for example, in Japanese Patent Laid-open No. 125481/1976, the method of this invention can provide an extremely effective process for continuously preparing the styrene polymer `- containing a low molecular weight polymer.
~` The styrene polymer which is the object of this invention includes the low molecular weight polymer having a number average molecular weight of 1,000 - 5,000 and a glass transition temperature ranging 40 - 80C, a styrene polymer consisting of 70 - 30 parts of above low molecular weight polymer and 30 - 70 parts of a high molecular weight polymer, and a mixture of above styrene polymer with a low molecular weight polyalefins.
¦ The monomer which constitutes so-called styrene polymer of this invention includes styrene and other vinyl monomar. The examples of other vinyl monomer which may be used include o-methyl styrene, m-methyl ~tyrene, p-methyl styrene, ~-methyl styrene, p-t-butyl styrene, vinyl naphthalene, vinyl chloride, vinyl fluoride, vinyl acetate, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, methyl acrylate, ethyl acrylate, -~t ", . ,,, , , ,,, " ,, , ~"~ ,, ,,j "" ~"~ , ",,, ,, " J ""- ,; ~ ~ " " : " ~ ", -`~ 1327~72 n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, dimethyl fumarate, di-i-propyl fumarate, di-n-butyl fumarate, di-i-butyl fumarate, dimethyl maleate, diethyl maleate, di-i-propyl maleate, di-n-butyl maleate~ di-i-butyl maleate, 2-vinyl-pyridine, 2-vinylpyrrole, N-vinylcarbazole, N-vinylindole and N-vinylpyrrolidone. At least one of these monomers can be copolymerized with styrene. In the practice of this invention, styrene alone or a mixture of styrene with methacrylic acid and/or methyl methacrylate is particularly preferred among these vinyl monomers.
Besides in this invention, a homogeneous mixture of polymer can also be prepared effectively by uniformly mixing other high molecular weight styrene polymer with the reaction mixture of low molecular weight polymer prior to applying the method of this invention. Furthermore the resulting mixture can also be added with at least one of the low molecular ; 25 weight polyoleffins such as low molecular weight ~ polypropylene, polyethylene wax, polytetrafluoroethylene :i .' ' ': .
1327~72 and the like to obtain a uniform mixture.
ccording to the method of this invention, the volatile ingredients can be eontinuously removed from the reaction mixture of styrene polymer containing the low molecular weight polymer, which was difficult to perform by the prior art. The volatile content of i aforesaid styrene polymer can always be reduced to ~ 0.3~ or less without remarkable variation in the d~ efficiency for removing the volatile ingredients. In ~ .
addition, such low content of volatile matter in the aforesaid styrene polymer can provide electrophoto~
~a graphic toner which is excellent in blocking resistance, offset resistance and electrostatic charge and is very valuable in the actual use.
The eguipment for separating the volatile ingredients in this invention includes, for example, that illustrated in Figures 1 and 2 which is disclosed -in Japanese Patent Laid-open No. 24411/1981. The subject to be treated in this disclosure is a reactive 20 mixture of polymer. The reactive polymer causes a ~"
crosslink`ing reaction by heating in the treatment and generated gel adheres to the pipe. Therefore the -~
object of eguipment; in above disclosure is to prevent blockage of pipes in the heat-exchanger. On the other hand, the subject of this invention to be treated is a reaction mixture of styrene polymer containing the ' ,.': ., .' ','; '' .
~ low molecular weight polymer and causes no gelling -~ reaction when heated. In addition, the object of using this equipment in this invention is to uniformly flow the reaction mixture into the heating zone of the heat-exchanger, remove the vola~ile ingredients ~ from the reaction mixture under uniform conditions ¦ and continuously prepare the low molecular weight styrene polymer having a very low content of the ' volatile ingredients. As mentioned above, the present invention is quite different from aforesaid disclosure in the subject and object of treatment.
A preferred example for continuously treating the reaction mixture in this invention will ~ -be illustrated as follows.
That is, vinyl polymer is carried out a bulk polymerization at 60 - 150C to a polymerization ratio of 30 - 90% by weight, successively added with a solvent to reduce viscosity of the reaction mixture and conducted a solution polymerization to obtain the high molecular weight polymer. A styrene type vinyl monomer is separately polymerized at a temperature of 190 - 230C in a state of solution to obtain the low molecular weight polymer.
~ ~ mixture is prepared from 30 - 70 parts `~25 by weight of the high molecular weight polymer as solid ~and 70 - 30 parts by weight of the low molecular weight , 1327~72 g polymer as solid.
`; Then the resulting mixture of polymer solu-~` tion is continuously treated by the method of this ~^ invention to separate the volatile ingredients from the styrene polymer. The resulting styrene polymer has a number average molecular weight (Mn) of 2,000 -15~000, a Z average molecular weight (Mz1 of not less than 400,000 and Mz/Mn of 50 - 600, and is suitable for the preparation of toner resin.
The present invention will hereinafter be illustrated with respect to examples. Unless otherwise indic~ted, part means part by weight.
Example 1 A reactor was charged with 70 parts of styrene and 30 parts of 1:1 solvent mixture of xylene and ethyl benzene and maintained at 210C. Polymer- `~
ization reaction was conducted by continuously feeding an uniform solution containing 0.5 mole of di-t-butyl ~ `
20 peroxide per 100 moles of styrene into the~reactor ;`
~ at a rate`of 750 cc/hr under the internal pressure -~
¦ of 6 kg/cm2. The resulting reaction mixture containing the low molecular weight polymer was charged at the same rate as above from the outlet of reactor through the inlet valve of volatile matter separation equipment to the circular-ring-shaped space of heat-exchanger.
: . .
'. ,.
;~' ,.. .
1327~72 The volatile matter separation equipment is illustrated in Figures 1 and 2. The equipment has outer double pipe for additional use as a jacket of circulating heat medium, concentrically located inner pipe of the 5 h~at exchanger for cir~ulating the heat medium and the circular-ring-shaped space formed between the outer and inner pipes. The heat medium was circulated the jacket and inner pipe at 210C. The temperature was 210C at the outlet of reactor and reduced to 190C
10 at the inside of heat-exchanger head by the foaming due to reduced pressure and latent heat of vaporization.
The reaction mixture was discharged into the vacuum chamber ; maintained at an absolute pressure of 20 mmHg and 3 a jacket temperature of 140C. The mixture wa~ separated 15 into gas and liquid phases by flashing and the liquid phase was collected in the bottom of chamber. The low molecular weight polymer had a temperature of 140C
after separating the volatile ingredients. The resulting polystyrene was continuously discharged from the 20 bottom of vacuum chamber and had a number average mo~ecular weight of 2,500, a glass transition tempera-! ture of 64C and a nonvolatile content of 99.9%.
The number average molecular weight was measured in accorda~nce with gel permeation chromatography ` ~ `
25 using polystyrene clS standard. The glass transition i temperature was measured according to DSC method. The - 13~72 non-volatile content is measured by precisely weighing the sample in a dish, heating it at 105C for 90 minutes and weighing the residual weight to calculate the loss. The same methods of analyses were also used -~ 5 in tne following Examples and Comparative Examples.
~3 .
Comparative Example 1 The reaction mixture of Example 1 containing ~ the low molecular weight polymer was heated by using a .3 10 multitubular heat-exchanger having the pipe outlet directly connecting with the vacuum chamber. The flowing down state of the polymer at the outlet of each pipe in the heat-exchanger was observed from the window equipped on tha vacuum chamber. The flow rate from each pipe was unstable and the non-volatile content of discharged polystyrene was reduced to :
8.9~.
Comparative Example 2 T~e procedures of Example 1 were repeated by using the same reaction mixture containing the low molecular weight polymer and employing the same heat exchanger having the same area of flow line and the same area of heat transmission except the circulation of heat medium through the inner pipe was omitted (that is, used as a hollow pipe). The non-volatile , .
;.'':
content of discharged polystyrene was reduced to 99.2~.
Example 2 The reaction mixture of Example 1 containing 5 the low molecular weight polymer was used as the first component. A high molecular weight styrene polymer derived from 70 parts of styrene and 30 parts of n-butyl acrylate and having a weight average molecular weight of 300,000 and a glass transition temperature 10 of 58C was used as the second component. The first and second components were respectively dissolved in xylene. Both xylene solutions were uniformly mixed in amounts to give a 50:50 weight ratio of the low molecular weight and high molecular weight polymers.
15 Thereafter the same procedures as in Example 1 were carried out by using the same volatile matter separation equipment. The resulting styrene polymer 3 was a homogeneous mixture of the high molecular weight T and low molecul~r weight polymers and had a non-20 volatile content of 99~8%.
Example 3 The reaction mixture of Example 1 containing `
the low molecular weight polymer was add with 5~ by 25 weight of low molecular weight polypropylene and unifonmly mixed. Thereafter the same procedures as `.
,, .~ .
1327~72 in Example 1 was carried out. The low molecular weight ' styrene polymer obtained was a homogeneous mixture with the low molecular weight polypropylene and had a non-volatile content of 99.9~.
` 5 i Example 4 Styrene methacrylic acid copolymer was prepared by using the same procedures as in Example 1 except 67 parts of styrene and 3 parts of methacrylic ~ 10 acid was used in place of 70 parts of styrene. The 3 resulting copolymer had a number average molecular ~ ~
weight of 3,800, a glass transition temperature of ~ ~`
70C, and a non-volatile content of 99.8%.
.:
15 Example 5 ~ `
I A nitrogen replaced flask was charged with ~ -72 parts of styrene and 28 parts of butyl acrylate as vinyl polymers, and heated to 12nC. Bulk polymerization was conducted for 10 hours at this temperature to `
20 obtain a conversion of 55~. Successively 30 parts of i xy]Lene wère added to prepare a solution. A mixture containing 0.1 part ~f dibutyl peroxide dissolved in 50 parts of xylene was continuously add to the solution I over 8 hours at 130C. The reaction was continuad for 25 an hour after completing the addition. The resulting j high molecular weight polymer was named A-l.
'.,'..
1327~72 ; - 14 -In the next step, solution polymerization was conducted by continuously adding a homogeneous solution of O.S mole of di-t-butyl peroxide in 100 moles of styrene at a rate of 750 cc/hr to the mixture consisting of 70 parts of styrene and 30 parts of a solvent mixture containing xylene and ethyl benzene.
The reaction conditions maintained were an internal reactor temperature of 210C, the internal pressure of 6 kg/cm2 and an outlet temperature of 100C.
The resulting low molecular weight styrene polymer had a conversion of 99.5% by weight. The t mole~ular weight was measured in accordance with gel t permeation chromatography by using monodispersed standard polystyrene as a reference sample and tetra-; 15 hydrofuran as an eluent. The number average molecular weight thus obtained was 2,100. --Besides the solid polymer A-2 was obtained by separately removing ~he solvent and its glass transition temperature (Tg) was measured with a differential scanning calorimeter by using alumina as ref~rence. The Tg measured was 70C.
A mixture was prepared from 50 parts of above low molecular weight styrene polymer A-2 and 90 parts of the aforesaid high molecular weight polymer A-l (50 parts as solid). The solvent was removed from the mixture by employing the same volatile matter ::
,.
:.'~' . ' :
1327~72 separation equipment of Example 1 as illustrated in Figures 1 and 2. The mixture was heated to 200OC and flashed into a vacuum system maintained at 10 mmHg by using almost the same conditions as in Example 1.
The resulting polymer had Mn of 2,800, Mz of 652,000, Mz~Mn of 233 and Tg of 57C. In addition the polymer had a residual volatile content of 0.09~.
The styrene polymer thus obtained was evaluated the characteristics for the electrophotographic -toner.
(Preparation of the toner) ..
In a Henshel mixer, 100 parts of the resin, 10 parts of carbon black (MA-100: a product of Mitsubishi Chemical Co.) as a coloring agent, 3 parts of poly-propylene wax and 0.5 - 2 parts of Spiron Black TRH as a charge regulator were mixed. The mixture was hot-~neaded with a twin screw extruder at a temperature of 140C (inlet) - 150C (outlet), cooled and crushed.
The resulting coarse particles were finely ground with a jet mill and subjected to air classification to obtain the toner having a particle size of 8 - 20 ~m [ll.S ~m in average). The resulting toner was mixed with 0.15 part of colloidal silica in Henshel mixer and tested.
The amount of charge controlling agent was '` '' ~ .
` 1327~72 controlled to obtain -15 ~C/g of electrostatic charge - after mixing 95 parts of the carrier for EP870 with 5 parts of the toner in a V-blender for 30 minutes.
~Evaluation as the Toner) Furthermore duplication characteristics were measure~ under the following conditions by Electro-photographic Copying Machine EP870 (a product from Minolta Camera Co.) equipped with Teflon hot-rolls.
Fixing ability: TM
A plastic eraser "NONO" (a product from Tombo Pencil Co.) was gone back and forth 20 times j with a constant force between a solid black part and a non-tonered white part on a duplicated sheet.
Toner removal from the black part and soil of the white part were observed and divided into the following four classes.
......... ....... No toner removal at all.
......... ....... Good.
~ ..... Toner was somewhat removed.
X ..... Poor. Toner was removed and caused much soil.
Contamination of the white background:
The white part of the 100th sheet was compared with that of the lO,OOOth sheet in a continuous copying operation. The degree of contamination on the ` ` 1327672 white background due to the scattering of toner was divided into the following three classes.
i ~- O ~.... Good, ... contamin~tion was observed with a magnifying glass having a magnification i of 30 times.
i~ X ...... Contamination was observed with the .~;
naked eye.
Offset resistance:
The offset refers to a phenomenon that a part of the toner is attached on the surface of a fixing roll and then transferred again onto the fresh surface of a paper after one rotation of the roll to cause the contamination of the paper.
O ... No contamination was found over 10,000 sheets of continuous copying operation.
X ... Contamination was found in the same ¦ conditions.
~ '`'`
Blo~cking resistance:
Blocking resistance was evaluated by observing the aggregation after allowing to stand the toner for 8 hours a~ the temperature of 55C under 80% relative humidity. Results were illustrated by the following four classes.
~.
"'.
: -..... . . ..
... No aggregation was found at all.
O ... Aggregation was found partially but easily unfastened.
~` ~ . . . Firm coagulate was founcl in part.
S X ...... Firm coagulate was found entirely.
,, .
Variation of electrostatic charge:
In the continuous copying operation, tribo-electrostatic charges of the 100th and lO,OOOth duplicates were expressed by the following ratio (absolute value).
?
(Amount of charge (Amount of charge after lO,OOOth - after 100th (Amount of charge after lOOtl~rpl-ica~te) x 100(%) `
,~' When the ratio was not more than 10(%), the 3 variation was considered good.
~Dispersibility of the coloring agent:
slide glass was put on a hot plate previou~ly heated at 250 - 300C and a small amount of the toner was placed on the slide glass. A cover gl~s was put on the toner sample simultaneously with the fusion of the toner and pressed with a given pressure for 60 seconds. The sample was taken out of the hot plate and allowed to cool. The dispersion of coloring agent was observed with an optical transmission microscope having a magnification of 400 - 1,000 times. ~`
", .;.:
:'; `
1327~72 .~ -- 1 9 .. .
The results of the observation was divided into the following two classes.
-`~ O ...... No undispersed or aggregated particles of ~- the coloring agent were found in any field of vision.
X ... Many undispersed or aggregated particles of the coloring agent were found.
Reproducibility of the completely solid black part:
Irregular gloss of the solid black part was observed on the 100th duplicate from the start of ; copying operation. The results were divided into the following three classes.
.~ .
¦ 15O ...... Irregulax gloss was slight.
~ ... Irregular gloss was found in some degree.
¦ `X ..... Irregulax gloss was remarkable.
- .
(Evaluation results as toner) . _ _ :
20 Fixing ability ~
. __ .__ _ ..
Contamination of the white background 1 Offset resistance O
_ __ ................................. _ Blocking resistance - O
. . . _ ': -Variation of electrostatic charge 5.2 -~' . . ............................................. , Dispersibility of the coloring agent O
., ~.~' . .
- .
Claims (3)
1. A continuous method of treating a polymer reaction mixture for separating a styrene polymer to be used for electrophotographic toner by continuously removing volatile ingredient from a reaction mixture containing the styrene polymer obtained by polymerizing styrene monomer alone or with other vinyl monomer, which comprises flowing down and preheating the reaction mixture containing said styrene polymer through a circular-ring-shaped space of a heat-exchanger, said heat-exchanger consisting of an outer double pipe as a jacket of circulating heat medium, a concentrically located inner pipe of the heat-exchanger for circulating the heat medium and the circular-ring-shaped space formed in between, and flashing the reaction mixture containing said styrene polymer into a vacuum chamber connected with said heat-exchanger to continuously separate the styrene polymer and the volatile ingredient; wherein the reaction mixture at least contains a low molecular weight polymer having a number average molecular weight of 1,000 -5,000 and a glass transition temperature of 40 - 80° C.
2. The method as claimed in Claim 1, wherein the styrene polymer is obtained by mixing 70 - 30 parts of said low molecular weight polymer and 30 - 70 parts of a high molecular weight polymer.
3. The method as Claimed in Claim 1, wherein the styrene polymer is obtained by blending the mixture of Claim 2 and a low molecular weight polyolefin.
Priority Applications (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/JP1987/000721 WO1989002902A1 (en) | 1987-09-30 | 1987-09-30 | Process for continuously treating a polymer reaction solution |
| EP87906451A EP0336963B1 (en) | 1987-09-30 | 1987-09-30 | Continuous method of treating a polymer reaction mixture |
| DE87906451T DE3788426T2 (en) | 1987-09-30 | 1987-09-30 | CONTINUOUS PROCESS FOR TREATING A POLYMER REACTION MIXTURE. |
| CA000552736A CA1327672C (en) | 1987-09-30 | 1987-11-25 | Continuous method of treating polymer reaction mixture |
| US07/966,570 US5362595A (en) | 1987-07-10 | 1992-10-26 | Electrophotographic toner production process |
| US08/029,360 US5334473A (en) | 1987-09-30 | 1993-03-10 | Continuous method of treating polymer reaction mixture |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/JP1987/000721 WO1989002902A1 (en) | 1987-09-30 | 1987-09-30 | Process for continuously treating a polymer reaction solution |
| PCT/JP1987/000719 WO1989000718A1 (en) | 1987-07-10 | 1987-09-30 | Toner for electrophotography |
| CA000552736A CA1327672C (en) | 1987-09-30 | 1987-11-25 | Continuous method of treating polymer reaction mixture |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1327672C true CA1327672C (en) | 1994-03-08 |
Family
ID=27167808
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000552736A Expired - Fee Related CA1327672C (en) | 1987-07-10 | 1987-11-25 | Continuous method of treating polymer reaction mixture |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1327672C (en) |
| WO (1) | WO1989002902A1 (en) |
-
1987
- 1987-09-30 WO PCT/JP1987/000721 patent/WO1989002902A1/en active IP Right Grant
- 1987-11-25 CA CA000552736A patent/CA1327672C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| WO1989002902A1 (en) | 1989-04-06 |
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