JPH0543731B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing vinyl chloride resin, and more specifically, the present invention relates to a method for producing vinyl chloride resin, and more specifically, when graft copolymerizing vinyl chloride onto an acrylic polymer latex by a suspension polymerization method, it is possible to produce a vinyl chloride resin with less scale. Regarding the manufacturing method. [Prior Art] As a method for obtaining a vinyl chloride resin having excellent weather resistance and impact resistance, a method of graft copolymerizing vinyl chloride onto an acrylic copolymer latex is known. However, when graft-copolymerizing vinyl chloride onto acrylic copolymer latex by suspension polymerization, the acrylic copolymer may Polymer called scale usually adheres to the parts of the equipment that come into contact with the copolymer latex and monomer, reducing the cooling capacity of the polymerization tank, or once the polymer adheres and peels off, it gets mixed into the vinyl chloride resin, causing quality problems. Problems such as a decrease in Therefore, it is customary to clean the inside of the polymerization tank each time after completion of polymerization and then perform polymerization again, but this requires a great deal of labor and time, resulting in a decrease in the operating rate of the polymerization tank and an increase in cost. Many methods have been proposed to prevent polymers from adhering to the inner walls of polymerization tanks.
Although these methods are effective in preventing polymer adhesion in the case of vinyl chloride homopolymerization, they are almost ineffective in graft copolymerization of vinyl chloride to acrylic copolymer latex, and neither method is used industrially. The method was not satisfactory. [Problems to be Solved by the Invention] An object of the present invention is to reduce the amount of polymer adhesion produced when graft copolymerizing vinyl chloride to an acrylic copolymer latex by a suspension polymerization method, thereby achieving practical polymerization. The purpose is to provide a method. [Means for solving the problem] The present inventors have conducted extensive research to achieve the above object, and have surprisingly found that if an acrylic copolymer latex with a specific structure is used, polymer adhesion can be reduced. The inventors have discovered that even a small amount of attached polymer can be easily removed by washing with water, etc., and that there are no adverse effects such as slowing down the polymerization reaction or deteriorating various physical properties of the product, and the present invention has been achieved. . That is, in the method for producing a vinyl chloride resin of the present invention, when graft copolymerizing vinyl chloride to an acrylic copolymer latex by a suspension polymerization method, acrylic copolymer 60 to 60 is used as the acrylic copolymer latex. The second-order transition temperature of the homopolymer is 99% by weight.
It is characterized by using a material obtained by graft copolymerizing 40 to 1% by weight of monomers at a temperature of 80°C or higher. In addition to alkyl acrylate and/or alkyl methacrylate, the acrylic copolymer latex used in the present invention is a copolymer with other copolymerizable monomers and also has a homopolymer secondary transition temperature. This is a copolymer latex obtained by graft copolymerizing monomers at a temperature of 80°C or higher. Examples of alkyl acrylate and alkyl methacrylate include methyl acrylate,
Ethyl acrylate, n-propyl acrylate, iso-butyl acrylate, n-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, n-decyl acrylate, n-dodecyl acrylate, lauryl acrylate, etc., and their methacrylates can be given. In addition, copolymerizable monomers include monofunctional monomers such as olefins such as ethylene, propylene, and hexene, aromatic vinyls such as styrene, α-methylstyrene, and vinyltoluene, and acrylonitrile and methacrylonitrile. Unsaturated nitriles, vinyl esters such as vinyl acetate and vinyl propionate, vinyl ethers such as butyl vinyl ether and lauryl vinyl ether, polyfunctional monomers such as ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate,
Mono- or polyalkylene glycol acrylates or methacrylates such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1.3-propylene glycol dimethacrylate, 1.3-butylene glycol dimethacrylate, 1.4-butylene glycol dimethacrylate, diallyl phthalate , di- or triallyl compounds such as diallyl maleate, diallyl fumarate, diallyl succinate, and triallyl isocyanurate, and divinyl compounds such as divinylbenzene and butadiene. The alkyl acrylate, alkyl methacrylate, and copolymerizable monomers may be used alone or in combination of two or more to obtain a copolymer. The acrylic copolymer used in the present invention is obtained by emulsion polymerization, and preferably has an average particle diameter of 0.01 to 10 μm as a latex. To obtain a copolymer using a general emulsion polymerization method, for example, pure water, an anionic emulsifier, and a water-soluble polymerization initiator are charged into a jacketed polymerization reactor, and the air inside the can is expelled. Next, monomers copolymerizable with alkyl acrylate and/or alkyl methacrylate are charged, and after emulsification, the inside of the can is heated with a jacket to start the reaction. The reaction is exothermic, and the internal temperature is controlled by the jacket as necessary. After the reaction is complete,
Unreacted monomers are removed from the can to obtain an acrylic copolymer in the form of a latex. The method of charging into the polymerization reactor is not limited. Further, if necessary, a particle size adjusting agent and a catalyst decomposition accelerator may be added to control the reaction. Examples of monomers whose secondary transition temperature of the homopolymer to be graft copolymerized to the acrylic copolymer is 80°C or higher include styrene, α-methylstyrene, aromatic vinyls such as vinyltoluene, acrylonitrile, methacrylonitrile, etc. Unsaturated nitrites, alkyl methacrylates such as methyl methacrylate and isopropyl methacrylate, and the like can be mentioned. These may be graft copolymerized alone or in combination of two or more. The amount of this monomer used is 0.01 to 40% by weight in the acrylic copolymer, more preferably 0.1 to 40% by weight.
30% by weight, most preferably 1 to 20% by weight. If it is less than 0.01% by weight, no scale prevention effect can be expected, and if it is more than 40% by weight, impact resistance will decrease, which is not preferable. In addition, if the acrylic copolymer contains a monomer whose secondary transition temperature in the homopolymer is 80°C or higher, the amount of monomer used in the graft copolymerization is reduced accordingly, and the acrylic graft copolymer is The amount of monomers with a homopolymer secondary transition temperature of 80°C or higher in the copolymer latex is 40% by weight.
It is desirable to keep the following. Graft copolymerization of a monomer with a homopolymer secondary transition temperature of 80°C or higher to an acrylic copolymer involves polymerizing the acrylic copolymer by emulsion polymerization, and then further grafting while the radicals are still alive. It is preferred to proceed by adding the monomers to be copolymerized, but the acrylic copolymer is separately polymerized,
A method may also be used in which emulsified particles having a predetermined particle size are subjected to graft copolymerization. In addition, as long as the monomer to be graft copolymerized is mainly a monomer whose homopolymer has a secondary transition temperature of 80°C or higher, other monomers may be included, and the acrylic copolymer latex may be graft copolymerized. In order to improve the properties of the vinyl chloride resin obtained by polymerization, it is desirable that other monomers be contained even in small amounts. Acrylic copolymer latex can be produced up to a concentration of approximately 50 wt% by the above method, but during production,
In terms of handling, it is advantageous to have a content of about 10 to 30 wt%. The amount of acrylic copolymer latex to be used is appropriately determined depending on the intended use of the final product. In the present invention, the acrylic copolymer latex is
The scale reduction effect remains the same even if graft copolymerization is carried out as is or after coagulation using suspension polymerization, but industrially, acrylic copolymer latex is coagulated and/or aggregated before chlorination. A method of graft copolymerizing vinyl can be carried out advantageously. Coagulates and/or coagulates acrylic copolymer latex.
Or in the case of agglomeration, after charging vinyl chloride,
The effect will be further improved if stirring is performed to disperse the coagulated and/or aggregated acrylic copolymer in the vinyl chloride. In that case, the temperature can be freely selected from 0°C to 65°C. When carrying out the aqueous suspension polymerization method, the amount of water used is 1 to 5 times, preferably 1 to 3 times, the total amount of the copolymer of the backbone polymer and the vinyl chloride monomer. The method of obtaining a graft copolymer resin by the suspension polymerization method of the present invention is, for example, in a jacketed polymerization reactor, pure water, a coagulant for acrylic copolymer latex, a radical polymerization initiator, a suspension stabilizer, If necessary, add a polymerization degree regulator, add the acrylic copolymer latex under stirring, and solidify it. Then, after removing the air inside the can, vinyl chloride is charged together with other vinyl compounds as necessary. do. Thereafter, the inside of the can is heated with a jacket to start graft copolymerization. Graft copolymerization is an exothermic reaction, and the internal temperature is controlled by the jacket as necessary. After the reaction is completed, unreacted vinyl chloride is removed from the can to obtain a slurry of graft copolymer resin. The slurry is dehydrated and dried in a conventional manner to obtain a graft copolymer resin. Note that the suspension stabilizer may be added after removing the air inside the can. In carrying out the present invention, it is advantageous to carry out the graft copolymerization by a radical polymerization method, and the radical polymerization initiators used for this purpose include lauroyl peroxide, tert-butyl peroxypivalate, diisopropyl peroxydi carbonate, organic peroxides such as dioctyl peroxydicarbonate, 2,2'-azobisisobutyronitrile, 2,2'-azobis-2,
Examples include oil-soluble polymerization initiators such as azo compounds such as 4-dimethylvaleronitrile, and water-soluble polymerization initiators such as potassium persulfate and ammonium persulfate. The amount of these polymerization initiators used is
The amount is preferably 0.005 to 1.0 parts by weight per 100 parts by weight. Dispersants include methylcellulose, ethylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, polyvinyl alcohol and partially saponified products thereof, gelatin, polyvinylpyrrolidone, starch, maleic anhydride.
Styrene copolymers, etc., and these may be used alone or in combination. The amount added is suitably 0.01 to 1.0 parts by weight per 100 parts by weight of vinyl chloride. Furthermore, in the present invention, a chain transfer agent used in conventional methods for polymerizing vinyl monomers may be added in an amount of 0.001 to 10 parts by weight per 100 parts by weight of vinyl chloride. [Effects of the Invention] If graft copolymerization is carried out by the method of the present invention, scale adhesion is reduced, so there is no decrease in the cooling capacity of the polymerization tank, and once attached scale peels off and comes into contact with the stirrer, reducing the stirring power. There is no need to worry about an increase in water content, there is almost no need for canning to remove scale, and the final product, the vinyl chloride resin, has improved firmness. [Example] Hereinafter, the present invention will be specifically explained with reference to Examples. Reference Example 1 [Production of acrylic copolymer latex] In a polymerization machine with an internal volume of 5 m ³ equipped with a stirring blade, 2000 kg of deionized water, 7.0 kg of anionic emulsifier, 0.7 kg of ammonium persulfate, and 630 kg of n-butyl acrylate were added.
Kg and 35 Kg of 1.3-butylene glycol dimethacrylate were put therein, and after replacing the internal air with nitrogen, polymerization was carried out at 60°C. Fifteen hours after the start of polymerization, the internal temperature began to rise rapidly, so heat was removed using a jacket and a backflow condenser. One hour later, 35 kg of methyl methacrylate was added.
The remaining monomer reaction was continued for another 10 hours to terminate the polymerization reaction. The concentration of the obtained latex was 26% by weight, and the particle size was 0.08 μm. Example 1 2700 kg of deionized water and partially saponified polyvinyl alcohol were placed in a polymerization machine with an internal volume of 7 m ³ equipped with a stirring blade.
2.05Kg, 2.05Kg of methylcellulose, 0.075Kg of 2.2'-azobisisobutyronitrile, 0.24Kg of 2,2'-azobis-2,4-dimethylvaleronitrile, and 15% concentration by weight of water produced using Reference Example 1. 600 kg of acrylic copolymer latex diluted with
After removing the air inside, 1410 kg of vinyl chloride was charged and polymerization was carried out at 57°C. Ten hours after the start of polymerization, the internal pressure of the polymerization machine decreased to 6.5 Kg/cm ² , so unreacted monomers were collected and the slurry was dehydrated and dried. During the polymerization reaction, there was no overload of stirring power, the amount of scale was very small at 0.7 kg, and the resulting resin had excellent fissure eye and shear ruby impact strength. Example 2 In a polymerization machine with an internal volume of 7 m ³ equipped with a stirring blade, 2700 kg of deionized water, 0.75 kg of partially saponified polyvinyl alcohol, 0.75 kg of methyl cellulose, and Al ₂ were added.
(SO ₄ ) ₃ 0.9Kg, 2,2'-azobisisobutyronitrile 0.075Kg and 2,2'-azobis-2,4-
After adding 0.24 kg of dimethylvaleronitrile and removing the internal air with a vacuum pump, the polymerization machine was heated at a temperature of 35℃ for 30 minutes.
Stirring was performed for a minute. 600 kg of the same acrylic copolymer latex (solid content: 90 kg) as used in Example 1 was charged into it while stirring, and solidified. Thereafter, 1410 kg of vinyl chloride was charged, and after stirring for 1 hour, 57 kg of
Polymerization was carried out at °C. Ten hours after the start of polymerization, the internal pressure of the polymerization machine decreased to 6.5 Kg/cm ² , so unreacted monomers were collected and the slurry was dehydrated and dried. There is no overload of stirring power during the polymerization reaction.
The amount of scale was very small at 1.2 kg, and the resulting resin had excellent fiber eye and sharpie impact strength. Example 3 Polymerization was carried out in the same manner as in Example 2, except that 0.375 kg _{of Ca(OH) 2 was} used instead of Al ₂ (SO ₄ ) 3 . There is no overload of stirring power during the polymerization reaction.
The amount of scale was very small at 0.8 kg, and the resulting resin had excellent mechanical strength and sharpie impact strength. Example 4 A copolymer latex having a composition of 70% by weight of n-butyl acrylate, 15% by weight of methyl methacrylate, 5% by weight of acrylonitrile, and 10% by weight of graft copolymerized methyl methacrylate was used as an acrylic copolymer latex. Using 840 kg (solid content: 210 kg) (concentration 25% by weight, particle size 0.07 μm), 2.325 kg, 2.325 kg, and 0.45 kg of partially saponified polyvinyl alcohol, methylcellulose, and 2,2'-azobisisobutyronitrile, respectively.
Kg, and reduced vinyl chloride to 1290Kg, 2,
Polymerization was carried out in the same manner as in Example 1, except that 2'-azobis-2,4-dimethylvaleronitrile was not used and the polymerization temperature was 60°C. 11 from the start of polymerization
After a period of time, the internal pressure of the polymerization machine decreased to 6.5 Kg/cm ² , so unreacted monomers were collected and the slurry was dehydrated and dried. During the polymerization reaction, there was no overload of stirring power, the amount of scale was very small at 1.0 kg, and the resulting resin had excellent fissure eye and sharpie impact strength. Example 5 Using the same acrylic copolymer as used in Example 4, the partially saponified polyvinyl alcohol and methyl cellulose were reduced to 0.9 kg each, and 0.45 kg of calcium citrate was added to produce an acrylic copolymer latex. Polymerization was carried out in the same manner as in Example 4, except that after coagulating in the same manner as in Example 2, vinyl chloride was added and the polymerization was started after stirring for 1 hour. There is no overload of stirring power during the polymerization reaction.
The amount of scale was very small at 1.1 kg, and the resulting resin had excellent fiber eye and sharpie impact strength. Example 6 840 kg of the same acrylic copolymer latex (solid content 210 kg) used in Example 4 was cooled and solidified with stirring, and mixed with 2700 kg of deionized water, 1.0 kg of partially saponified polyvinyl alcohol, and methyl cellulose. After charging the reactor with 1.0 kg and removing the air inside, the temperature was raised to 60°C and stirred for 30 minutes. Next, 1290 kg of vinyl chloride was charged, and after stirring for 3 hours, 0.45 kg of 2,2'-azobisisobutyronitrile dissolved in acetone was charged, and polymerization was started. Eleven hours after the start of polymerization, the internal pressure of the polymerization machine decreased to 6.5 Kg/cm ² , so unreacted monomers were collected, and the slurry was dehydrated and dried. There was no overload of stirring power during the polymerization reaction, the amount of scale was very small at 1.2 kg, and the resulting resin had excellent fissure eye and sharpie impact strength. Comparative Examples 1-3 An acrylic copolymer latex randomly copolymerized to have the same composition as in Example 1 was used, and the same operations as in Examples 1-3 were carried out. Overload of stirring power occurred 8.5 to 9 hours after the start of polymerization, and the amount of scale decreased to 10
Kg, 13Kg, 12Kg, and the resulting resin had no problem in shear py impact strength, but its impact strength was poor. Comparative Examples 4 to 6 An acrylic copolymer latex randomly copolymerized to have the same composition as in Example 4 was used, and the same operations as in Examples 4 to 6 were carried out. Overload of stirring power occurred 9.5 to 10 hours after the start of polymerization, and the amount of scale decreased to 15
Kg, 6 Kg, and 18 Kg, and although the resulting products had no problem with the mechanical impact strength, the impact strength was poor. Comparative Example 7 As an acrylic copolymer latex, 94.999% by weight of n-butyl acrylate, 5% by weight of 1,3-butylene glycol dimethacrylate, and graft copolymerized methyl methacrylate were used.
The same operation as in Example 2 was carried out except that 0.001% by weight was used. An overload of the stirring power occurred 9.5 hours after the start of polymerization, and the amount of scale was as large as 13 kg, and the resulting resin had poor firmness. Comparative Example 8 As an acrylic copolymer latex, 54% by weight of n-butyl acrylate, 5% by weight of acrylonitrile
The same procedure as in Example 2 was carried out except that 41% by weight of graft copolymerized methyl methacrylate was used. There is no overload of stirring power during the polymerization reaction.
The amount of scale was as low as 1.2 kg, and the resulting resin had excellent firmness, but the shear py impact value was low. Table 1 summarizes the measurement results of polymerization time, yield, scale amount, and various physical properties of the obtained resins for the above Examples and Comparative Examples. The particle size distribution, average particle diameter and fish eye test were as follows. (1) Particle size distribution is JIS standard sieve 60, 80, 100,
Stack 150, 200, 270 meshes and saucers in that order,
Place 50g of sample on the sieve located at the top, and
After being vibrated with a sieve shaker for a minute, the proportion of resin present on each sieve and on the tray was determined and expressed in weight percent. (2) The average particle size is calculated by plotting the cumulative total of the remaining percentage of each mesh on the horizontal axis of the normal probability table and the opening of each mesh (μ) on the vertical axis.
m), and the cumulative total is 50% eye opening (μ
m). (3) Fisher Eye test method PVC 100g Di-2-ethylhexyl phthalate 50g Toa Rika stabilizer Adbastab BC-1゜000J
5g The above mixture is kneaded for 5 minutes using two rolls at 150°C with a roll spacing of 0.3mm, and then a sheet is prepared. Count the number of fish eyes present in the 10 cm x 10 cm area of this sheet by looking through it.

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Claims (1)

[Claims] 1. When producing a graft copolymer by graft copolymerizing vinyl chloride onto an acrylic copolymer latex by a suspension polymerization method, the acrylic copolymer latex contains 60 to 99% by weight of the acrylic copolymer.
A method for producing a vinyl chloride resin, characterized in that 40 to 1% by weight of a monomer whose homopolymer has a secondary transition temperature of 80° C. or higher is graft copolymerized.