Process of producing polymeric binder for toner

FIELD: polymer production.

SUBSTANCE: invention relates to production of polymeric binders for toner and can be used for copying appliances and printers. Process comprises separate preparation via emulsion polymerization of (i) low-molecule weight copolymer of styrene (α-methylstyrene), 2-ethylhexyl acrylate (or butyl acrylate) and methacrylic acid at monomer weight ratio (88-91.5):(8-11):(0.5-1.0) with intrinsic viscosity in toluene 0.08-1.2 dL/g and (ii) high-molecule weight copolymer of styrene (α-methylstyrene) and 2-ethylhexyl acrylate (or butyl acrylate) at monomer weight ratio (88-92):(8-12) with intrinsic viscosity in toluene 1.0-1.28 dL/g. In both cases, polymerization is carried out at 60-70% to monomer conversion close to 100%. Resulting latexes of low- and high-molecule weight copolymers are supplemented by stopper and antioxidant and then mixed with each other at "dry" weight ratio between 70:30 and 75:25 and coagulated intrinsic viscosity in toluene 1.0-1.28 dL/g. with electrolyte solutions to form polymer characterized by intrinsic viscosity in toluene 0.4-0.45 dL/g and polydispersity Mw/Mn, which ensures bimodal molecular weight distribution of copolymer. The latter has melting (spreading) point 125-137°C and softening temperature 70-75°C.

EFFECT: improved quality of electrographic printing.

2 cl, 1 tbl, 4 ex

 

The present invention relates to the production of a polymeric binder for toner. Polymeric binders are the basis of the electrophotographic compositions (toners for copiers and printers.

Known methods for producing polymeric binder based on polystyrene with a low molecular weight type PSN and its copolymer with butyl acrylate - PSNB.

However, these binders are not widely used in modern copiers due to low quality copies.

The closest to the technical nature of the proposed method is a method of obtaining a binder for toner, described in U.S. patent No. 5321091. According to the method is carried out radical polymerization ethyleneamines monomer or mixture Ethylenediamine monomers in the absence or in the presence of initiators. The obtained low molecular weight polymer dissolved in the polymerized monomers to hold mortar or suspension polymerization to obtain a resinous product. Obtained a resinous product is a polymer or copolymer ethyleneamines monomer or mixture Ethylenediamine monomers containing not more than 70% insoluble in tetrahydrofuran (THF) substances having a polydispersity equal to 5, with a peak in the region of molecular weight of from 2000 to 10000 in mo is colerne-mass distribution and the peak in the region of from 15,000 to 100,000 in molecular weight distribution of soluble in THF parts and component in a mixture with a polymer with a molecular weight of not more than 10000 number of from 10 to 50% by weight resin composition, softening temperature which is 50°With, a polydispersity not exceeding 15.

The disadvantage of this method is the long duration of polymerization (6-60 hours). Furthermore, the binder has a wide range of molecular weights in the low molecular weight part and the lack of reproducibility of the properties of the polymer obtained after dissolution of such low molecular weight polymer in the monomer and subsequent polymerization. Thus obtained polymer contains insoluble (crosslinked) part, and the peak has a high molecular weight component in the interval 15000-100000.

It is known that to ensure the high quality Xerox toner binder should have a molecular mass distribution (MMD) of low molecular weight peak of about 15,000 and high-molecular - level 500-800000.

The present invention is to obtain a polymeric binder for toner, providing a high-quality image in electrophotographic printing by increasing the sharpness of the image and improve the ability of the polymer to be kept on paper, and reducing the time of polymerization.

This result is achieved by a method of obtaining a polymer binder for a toner by the polymerization of styrene (α-methylstyrene) with acrylic monomers, according to which the WMD receive separate emulsion polymerization of a low molecular weight copolymer of styrene (α -methylstyrene), 2-ethylhexyl acrylate or butyl acrylate and methacrylic acid in a ratio of monomers (parts by weight) (88-91,5):(8-11):(0.5 to 1.0) with the characteristic viscosity in toluene of 0.08 and 0.12 DL/g and a high molecular weight copolymer of styrene (α-methylstyrene) with 2-hexyl acrylate or butyl acrylate with a ratio of monomers (parts by weight) (88-92):(8-12), respectively, with a characteristic viscosity in toluene and 1.0 of 1.28 DL/g, both polymerization is carried out with a conversion of the monomers is close to 100%, at a temperature of from 60 to 70°obtained latexes low molecular weight and high molecular weight copolymers are added, a stopper and an antioxidant, mix them in a weight ratio of dry matter from 70:30 to 75:25 and coagulated with a solution of electrolytes, get polymer with a characteristic viscosity of 0.4-to 0.45 DL/g and a polydispersity Mw/Mn19-32, providing a bimodal molecular weight distribution of the copolymer.

The resulting polymer has a melting temperature (spreading) 125-137°and the softening temperature of 70-75°C.

The polymer has a bimodal molecular weight distribution with peaks in the area of 15000 and 600-800 thousand when assessing his MMD in a solution of dimethylformamide.

These characteristics of the polymeric binder for toners provide high quality electrophotographic printing.

When receiving alimango binder for toner can be used as auxiliary substances, emulsifiers, based on the alkyl - and arylsulfonate, the alkyl sulphonates, disproportionating rosin, natural and synthetic fatty acids.

As the polymerization initiators can be used peroxide and gidroperekisi (potassium persulfate, Gidropress of cumene, benzoyl peroxide), azoisobutyronitrile.

As a polymerization activator applicable, sodium sulfite, triethanolamine, rongalit, Trilon B, iron semiwide riser, as a regulator of the molecular weight can be used tert-dodecylmercaptan, ciproxin (diisopropylcarbodiimide), bis-ethylxanthate.

As a polymerization stopper may be used sodium dimethyldithiocarbamate, diethylhydroxylamine, hydroquinone, as an antioxidant netanayahu type - Agidol-2 polygard (tennispalatsi), JSC-6 (trimethylbenzenesulfonyl), P-23 (2,4,6-tri-tert-butylphenol).

Coagulation of the latex exercise with alum, aluminium sulphate, calcium chloride.

All of these products provide the necessary quality of polymeric materials for toner and physical characteristics, provided by the invention.

The present invention is illustrated by the following examples.

Example 1.

In polymerization having a jacket and a stirrer, load (in parts by weight): styrene 90, 2-ethyl hexyl acrylate 10, sulfinol 4, lane is Ulfat potassium 04, sodium sulfite 0,2, water 200, tert-dodecylmercaptan 0,05 include stirring, bring the mixture to 60°and conducting polymerization until the conversion of the monomers is close to 100%. The resulting latex is discharged, charged with sodium dimethyldithiocarbamate in the amount of 0.2 parts by weight, and introduce the antioxidant - bis-(5-methyl-3-tert-butyl-2 oksifenil)methane or Agidol 2 in the amount of 0.5 parts by weight of the resulting polymer is recovered from the latex by ethanol, dried and analyzed. The characteristic viscosity of the polymer in toluene is 1.12 DL/g Later in the unit load (in parts by weight): styrene 90, 2-ethyl hexyl acrylate 10, methacrylic acid 0,5, sulfinol 4, potassium persulfate and 0.4, sodium sulfite 0,2, water 200, tert-dodecylmercaptan 4 include stirring, raise the temperature in the apparatus to 65-70°and conducting polymerization until the conversion of monomer to 100%. Curing time is 5 hours. The resulting latex is discharged, stoppering the sodium dimethyldithiocarbamate in the amount of 0.2 parts by weight, filled with antioxidant - Agidol-2 in the amount of 0.5 parts by weight of the resulting polymer is recovered from the latex of ethyl alcohol, dried, and determine the characteristic viscosity in toluene, which is 0.1 DL/g

The obtained latex of low molecular weight and high molecular weight polymers are mixed in a weight ratio of dry matter 75:25. To the resulting mixture on billaut 1%, considering dry matter, resinate sodium in the form of a 9% solution in water. The mixture was thoroughly mixed and coagulated 5% solution of aluminum sulfate. The coagulation temperature is 60°C. When the polymer precipitates in the form of crumbs the size of 1-2 mm Crumb is separated from the serum, washed with water, wrung out excess water and dried in an air dryer at a temperature not above 60°C. After drying the crumb polymer is ground to the size of the grains is not more than 1 mm, the Characteristic viscosity of the mixed polymer was 0.45 DL/g Properties of the obtained polymer are shown in table.

Example 2.

In polymerization having a jacket and a stirrer, load (in parts by weight): styrene 88, 2-ethyl hexyl acrylate 12, alkilsulfonat sodium 4, potassium persulfate 0,45, sodium sulfite 0,25, water 200, tert-dodecylmercaptan 0,06 include stirring, bring the mixture to 65°and conducting polymerization until the conversion of the monomers is close to 100%. The resulting latex is discharged, charged with sodium dimethyldithiocarbamate in the amount of 0.2 parts by weight and type antioxidant Agidol 2 in the amount of 0.5 parts by weight In a dedicated latex polymer determine the characteristic viscosity in toluene at 20°C. It is 1.0 DL/g Later in the unit load (in parts by weight): styrene 91,5, 2-8 hexyl acrylate, methacrylic acid, 0,5, sulfinol 4, potassium persulfate 0,41, sulfi the sodium 0,2, water 200, tert-dodecylmercaptan 4,0 include stirring, raise the temperature to 60°and conducting polymerization for 5.5 hours until the conversion of monomer to 100%. In the resulting latex injected sodium dimethyldithiocarbamate in the amount of 0.2 parts by weight, the antioxidant Agidol 2 in the amount of 0.5 parts by weight of the resulting polymer determine the characteristic viscosity in toluene at a temperature of 20°that is 0.08 DL/g

The obtained latex of low molecular weight and high molecular weight polymers are mixed in a weight ratio of dry matter 70:30, add resinat sodium 1 parts by weight and coagulated 5% solution of aluminum sulfate, washed, dried at 60°to a moisture content of not more than 0.5%. Determine the characteristic viscosity in toluene at 20°C. It is 0.45 DL/g Properties of the obtained polymer are shown in table.

Example 3.

In polymerization, equipped with a jacket and a stirrer, was loaded (in parts by weight): styrene 92, butyl acrylate, 8 sultanol 4, potassium persulfate and 0.4, sodium sulfite 0,2, water 200, tert-dodecylmercaptan 0,045 include stirring, raise the temperature in the apparatus 70°and conducting polymerization until the conversion of the monomers is close to 100%. In the resulting latex add sodium dimethyldithiocarbamate in the amount of 0.2 parts by weight, the antioxidant Agidol 2 in the amount of 0.5 parts by weight of the resulting polymer determine the nature of the socialist viscosity in toluene at 20° With, which is of 1.28 DL/g In an apparatus equipped with a stirrer and a jacket for heating load (in parts by weight): styrene 88, 11 acrylate, methacrylic acid, 1.0, sulfinol 4, potassium persulfate and 0.4, sodium sulfite 0,2, water 200, tert-dodecylmercaptan of 4.0. Conduct the polymerization at a temperature of 65°With up to a conversion of the monomers is 100%. In latex injected sodium dimethyldithiocarbamate in the amount of 0.2 parts by weight, the antioxidant Agidol 2 in the amount of 0.5 parts by weight of the resulting polymer determine the characteristic viscosity in toluene at a temperature of 20°that is 0.12 DL/g

The obtained latex of low molecular weight and high molecular weight polymers are mixed in a weight ratio of dry matter 75: 25 and coagulated potassium alum (10% solution), washed, dried at 60°With up to a moisture content of 0.5%. Determine the characteristic viscosity in toluene at 20°that is 0.42 DL/g Properties of the obtained polymer are shown in table.

Example 4.

In polymerization, equipped with a jacket and a stirrer, was loaded (in parts by weight): styrene 72, α-methylsterol 20, butyl acrylate, 8 sultanol 4, potassium persulfate 0,45, sodium sulfite 0,2, water 200, tert-dodecylmercaptan 0,06 include stirring, raise the temperature in the apparatus 80°and conducting polymerization until the conversion of monomer 98-100%. In the resulting latex add dimethyldithio the Mat sodium in amount of 0.2 parts by weight, antioxidant Agidol 2 in the amount of 0.5 parts by weight of the resulting polymer determine the characteristic viscosity in toluene at 20°S, which amounts to 1.1 DL/g In polymerization equipped with a stirrer and a jacket for heating load (in parts by weight): styrene 71, α-methylsterol 20, butyl acrylate 8,5, methacrylic acid 0,5, sulfinol 4,2, potassium persulfate 0,45, sodium sulfite 0,25, water 200, tert-dodecylmercaptan 4,1. Include mixing and raise the temperature to 70°C. the polymerization Process leading to conversion of the monomers is close to 100%. The resulting latex is charged with sodium dimethyldithiocarbamate in the amount of 0.2 parts by weight and type antioxidant Agidol 2 in the amount of 0.5 parts by weight Determine the characteristic viscosity in toluene at a temperature of 20°that is 0.09 DL/g Next latexes low molecular weight and high molecular weight polymers are mixed in a weight ratio of dry matter 75:25 and coagulated with a solution of aluminum sulfate, washed and dried. Determine the characteristic viscosity of the mixed polymer in toluene at 20°that is of 0.44 DL/g Properties of the obtained polymer are shown in table.

Properties of polymers (binders for toner) on the basis of copolymers of styrene
Indicesthe example 1 Example 2Example 3Example 4
The characteristic viscosity of the low molecular weight polymer in toluene at 20°C, DL/g0,10,080,120,09
Characteristic viscosity of high molecular weight polymer in toluene at 20°C, DL/g1,121,01,281,1
The characteristic viscosity of the mixed polymer in toluene at 20°C, DL/g0,450,40,420,44
Softening temperature,°73707575
The melting temperature (spreading),°133125137136

As can be seen from the table, the polymer is fully compliant to the binder for toner and provides high quality images in electrophotographic printing.

1. A method of obtaining a polymer binder for a toner by the polymerization of styrene (α-methylstyrene) with acrylic monomers, characterized in that the receive separate emulsion polymerization of a low molecular weight copolymer of styrene (α-methylstyrene), 2-ethylhexyl acrylate or butyl acrylate and meta is iloveu acid at the ratio of monomers (parts by weight) (88-91,5):(8-11):(0.5 to 1.0) with the characteristic viscosity in toluene of 0.08 and 0.12 DL/g and a high molecular weight copolymer of styrene (α -methylstyrene) with 2-hexyl acrylate or butyl acrylate with a ratio of monomers (parts by weight) (88-92):(8-12), respectively, with a characteristic viscosity in toluene and 1.0 of 1.28 DL/g, both polymerization is carried out with a conversion of the monomers is close to 100%at a temperature of from 60 to 70°C

the obtained latex of low molecular weight and high molecular weight copolymers are added, a stopper and an antioxidant, mix them in a weight ratio of dry matter from 70:30 to 75:25 and coagulated solutions of electrolytes, get polymer with a characteristic viscosity in toluene 0,4-0,45 DL/g and a polydispersity Mw/Mn19-32, providing a bimodal molecular weight distribution of the copolymer.

2. The method according to claim 1, characterized in that the obtained polymer has a melting temperature (spreading) 125-137°and the softening temperature of 70-75°C.



 

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