JPH0428003B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention is applicable to mortar, slate,
This article relates to a method for producing vinyl acetate/acrylic copolymer, which is useful as a resin for paints applied to concrete, roof tiles, etc. (Prior art) Vinyl acetate-acrylic paints, whose main component is vinyl acetate-acrylic copolymer (hereinafter abbreviated as "vinyl acetate"), have excellent coating workability and are relatively inexpensive, so they are suitable for the above-mentioned applications. However, compared to acrylic paints whose main component is an acrylic copolymer that does not contain vinyl acetate components, their gloss, water resistance, alkali resistance, and weather resistance are not necessarily satisfactory. In addition, pigment dispersibility,
Workability was also poor. Therefore, the following has been proposed to improve these shortcomings. (1) In order to improve the pigment dispersibility and gloss of acetic acid-acrylic paints, various studies have been made to improve the dispersibility of various pigments such as carbon black and titanium white. For example, Japanese Patent Publication No. 48-39215 , Special Publication No. 55-25322, Special Publication No. 1982-
No. 23791, Japanese Patent Publication No. 57-67613, and Japanese Patent Publication No. 57-67613 disclose hydrophilic functional groups such as maleic anhydride, saturated branched fatty acid vinyl, basic monomers, acidic monomers, and unsaturated dicarboxylic acids. It has been proposed to improve pigment dispersibility and improve gloss by copolymerizing an appropriate amount of a polymerizable monomer having the following. Also, JP-A-57
-80408 and JP-A-57-100165 disclose that pigment dispersibility is improved by copolymerizing an appropriate amount of an acid anhydride with a specific structure, such as alkenyl succinic anhydride, and then neutralizing it with a base. It has been proposed to improve gloss. (2) For the same purpose as (1), Special Publication No. 58-50647 states:
By performing a polymerization reaction in the presence of an alkyd resin to obtain biacrylic acetate, pigment dispersibility is improved,
It has been proposed to improve gloss. (3) In addition to improving gloss by improving pigment dispersibility as in (1) and (2) above, by lowering the molecular weight of the copolymer or increasing the vinyl acetate content. Known to improve gloss. (4) A method of increasing the molecular weight or a method of increasing the content of methyl methacrylate component is known for the purpose of improving water resistance, alkali resistance, and weather resistance. (5) As a method for obtaining biacrylic acetate for paints that has good gloss, water resistance, alkali resistance, and weather resistance, JP-A-60-96636 describes (a) biacrylic acetate with a low content of vinyl acetate. A method using a blend of acetic acid and biacrylic acetate with a high content of vinyl acetate, and (b) a method of solution polymerizing vinyl acetate and acrylic monomer in the presence of biacrylic acetate with a high content of vinyl acetate have been proposed. There is. (Problems to be Solved by the Invention) However, in the method (1) described above, gloss is improved by improving pigment dispersibility, but acid anhydrides neutralized with hydrophilic monomers and bases do not have hydrophilic properties. Due to the presence of functional groups, water resistance, alkali resistance, and weather resistance are reduced.Also, in method (2) mentioned above, gloss is improved due to improved dispersibility, but water resistance, alkali resistance, and weather resistance are reduced. It may decrease. As described above, gloss can be improved by any of the methods for improving pigment dispersibility, but there is a problem in that water resistance, alkali resistance, and weather resistance deteriorate. Furthermore, although the method (3) described above can improve gloss, it has the problem of deteriorating water resistance, alkali resistance, and weather resistance. On the other hand, method (4) mentioned above is
Although it is possible to improve water resistance, alkali resistance, and weather resistance, there is a problem in that the gloss decreases. In addition, in method (5) mentioned above, the synthesis of biacrylic acetate with a high content of vinyl acetate and biacrylic acetate with a low content of vinyl acetate is carried out by normal batch polymerization, so the polymerization time is 20 to 40 hours. In addition to the length of the process, each process must be polymerized separately, leading to problems such as very poor productivity and complicated operations. In addition, in this batch polymerization, in order to shorten the polymerization time,
Usually, a method is used to add a polymerization initiator in the late stage of polymerization, but adding a polymerization initiator reduces the molecular weight of the copolymer produced in the late stage of polymerization, and the copolymer has a low vinyl acetate content. As a result, there is a problem in that water resistance, alkali resistance and weather resistance are significantly reduced. An object of the present invention is to solve the above-mentioned problems and provide a method for producing with high productivity acetic acid acrylic paint for paints that has good gloss, water resistance, alkali resistance, and weather resistance. (Means for Solving Problems) The present invention provides at least two raw material monomer components containing vinyl acetate and methyl methacrylate as main components.
In a production method in which unreacted monomers are removed after continuous polymerization in a multi-stage continuous stirred tank reactor in which methacrylic acid is polymerized in at least one continuous stirred tank reactor connected in series, This invention relates to a method for producing a vinyl acetate/acrylic copolymer, which produces a copolymer with a methyl mole fraction of 0.65 to 0.93, and which reduces the polymerization rate in the final stage of a continuous stirred tank reactor to 80% or less. continuous stirred tank reactor
A tank reactor (hereinafter abbreviated as CSTR) is a reactor that is configured to continuously supply raw materials such as monomers, initiators, and solvents from one end of the reactor for reaction, and simultaneously take out products from the other end. It is a vessel,
For stirring, a stirrer such as a turbine blade, paddle blade, or double helical blade is usually installed, but if natural stirring is achieved by refluxing the monomer or solvent, the stirrer can be omitted. .
Stirring is preferably carried out so that a substantially complete mixed flow (see Polymerization Chemistry Exercises, edited by the Society of Polymer Science, p. 137) is established. When multiple CSTRs are connected in series,
The number of CSTRs is referred to as the number of stages, and in the present invention, the number of stages is two or more, preferably 10 or less. If the number of stages is only one, only one with a uniform copolymer composition can be produced, and paints containing such a copolymer as a main component have poor properties such as gloss or water resistance and are not suitable for use. If there are too many stages,
An increase in the number of CSTRs increases equipment costs and makes operation and operation troublesome, so 10 stages or less is preferable. Unreacted monomers in the reaction solution after polymerization reaction (continuous polymerization) in multiple stages of CSTR need to be removed. Paints whose main component is a copolymer that still contains unreacted monomers have a problem with monomer odor, have poor drying properties, and have poor properties such as water resistance. Removal of unreacted monomers can be carried out by known methods such as distillation of monomers, but it is preferably carried out using a continuous distillation column. This continuous distillation column is not particularly limited as long as it can separate unreacted monomers, and may be a packed column, plated column, or the like.
The unreacted monomers separated by distillation may be extracted from the system and disposed of or used for other purposes, but in consideration of economic efficiency, it is preferable to circulate them as they are to the CSTR and reuse (recycle) them. In the present invention, it is necessary to set the molar fraction of methyl methacrylate in the copolymer produced in at least one CSTR to 0.65 to 0.91, and
It is particularly preferable that the molar fraction of methyl methacrylate in the copolymer produced by CSTR is 0.65 to 0.93, since it is easy to adjust the molar fraction of the copolymer. The mole fraction of methyl methacrylate is 0.65~
In order to newly generate a copolymer of 0.93 in the second and subsequent stages of CSTR, for example, all or part of the methyl methacrylate in the raw material is transferred to a predetermined second and subsequent stage of CSTR.
This can be achieved by supplying to CSTR. In this case, checking whether the mole fraction adjustment has been carried out as desired is done by checking the copolymer flowing out from the previous stage CSTR (sampled at the previous stage outlet) and the copolymer flowing from the previous stage CSTR.
Copolymer flowing out from CSTR (at the outlet of the relevant stage)
This can be done by knowing the mole fraction of the copolymer newly produced in the relevant stage based on the mole fraction of the copolymer (sampled by CSTR) and the polymerization rate of the previous stage and the relevant stage. The molar fraction (M) of the copolymer obtained can be calculated using the following formula. M=XbMb−XaMa/Xb−Xa Here, Xa is the polymerization rate of CSTR in the previous stage, Xb
is the polymerization rate of CSTR in the relevant stage, Ma is the polymerization rate in the previous stage
The mole fraction of methyl methacrylate in the copolymer flowing out from the CSTR and Mb is the mole fraction of methyl methacrylate in the copolymer flowing out from the CSTR of the stage. In addition, in the present invention, the polymerization rate (X) is defined by the following formula. X=F _P /F _M +F _P ×100 (%) Here, F _P is the flow rate of the copolymer flowing out from the CSTR (Kg/hr), and F _M is the flow rate of the total monomer flowing out from the CSTR. (Kg/hr). Furthermore, the mole fraction of the copolymer can be determined by analyzing the composition using nuclear magnetic resonance spectroscopy (NMR). If a copolymer with a molar fraction of methyl methacrylate of 0.65 to 0.93 in any CSTR is not formed, water resistance or gloss will be insufficient. FIG. 4 shows a curve showing the relationship between the polymerization rate and the molar fraction (instantaneous value) of methyl methacrylate in the copolymer produced when the reaction is carried out using one CSTR. The curve in Figure 4 shows the reactivity of methyl methacrylate (r ₁ = 26) and the reactivity of vinyl acetate when the (mole fraction) of the raw material monomers is 0.36 methyl methacrylate and 0.64 vinyl acetate, and the reaction temperature is 82°C. Ratio (r ₂ =
0.003) (see Copolymerization-1, edited by The Society of Polymer Science, p. 59). As is clear from Figure 4, when the polymerization rate is less than 5%, the molar fraction of methyl methacrylate in the resulting copolymer exceeds 0.93, while when the polymerization rate exceeds 55%, the copolymer is formed. The mole fraction of methyl methacrylate in the copolymer is
It can be seen that it is less than 0.65. As mentioned above, the molar fraction of the copolymer produced is closely related to the polymerization rate, and as shown in Figure 4, the molar fraction of methyl methacrylate in the copolymer produced is The curve showing the relationship between (instantaneous value) differs depending on the raw material monomer composition (mole fraction), so the mole fraction of methyl methacrylate in the copolymer produced in at least one CSTR is It is necessary to select the polymerization rate so that the ratio is in the range of 0.65 to 0.93. The polymerization rate is
Since it depends on the reaction temperature and residence time, it is necessary to select an appropriate reaction temperature and residence time. In addition, in the present invention, the residence time (θ (hr))
is defined by the following equation. θ=Vr/F (hr) Here, Vr is the amount of reaction liquid in the CSTR (), and F is the flow rate of the liquid supplied to the CSTR (/hr). In the present invention, the weight ratio of the final stage CSTR is 80
% or less. When the polymerization rate of CSTR in the final stage exceeds 80%, the amount of homopolymerized low molecular weight vinyl acetate increases. In such cases, paints using acetic acid biacrylic have reduced water resistance. In the present invention, it is preferable that the mole fractions of vinyl acetate and methyl methacrylate in the copolymer flowing out from the final stage CSTR are 0.73 to 0.33 for vinyl acetate and 0.27 to 0.67 for methyl methacrylate. If the molar fraction is within this range, a coating material using the obtained copolymer will have better gloss, water resistance, alkali resistance, and weather resistance. The mole fractions of vinyl acetate and methyl methacrylate in the copolymer flowing out from the final stage CSTR are set to 0.73 to 0.33 for vinyl acetate and 0.27 to 0.27 for methyl methacrylate.
The value of 0.67 can be achieved mainly by adjusting the molar fraction of vinyl acetate and methyl methacrylate as raw material monomers supplied to the polymerization system. If the polymerization system is such that the amount of monomer supplied (Kg/h) is equal to the amount of copolymer flowing out from the final stage CSTR (Kg/h), from the continuous stirred tank reactor in the final stage The mole fractions of vinyl acetate and methyl methacrylate in the copolymer flowing out were determined to be 0.73 to 0.33 for vinyl acetate and 0.27 to 0.67 for methyl methacrylate.
In order to
This can be done by setting the value to ~0.67. It is preferable from the standpoint of equipment, operation, etc. that all monomers supplied to the polymerization system be supplied to the first stage CSTR. In the present invention, the molar fraction of vinyl acetate and methyl methacrylate as raw material monomer components is preferably 0.73 to 0.33 for vinyl acetate and 0.27 to 0.67 for methyl methacrylate. The paint used has poor gloss, water resistance, etc. The most preferred mode of carrying out the invention is
Final stage CSTR with 2 to 3 CSTRs connected in series
Next, using a reaction apparatus configured with a continuous distillation column connected, the raw material monomers and polymerization initiator were adjusted to have a molar fraction of vinyl acetate and methyl methacrylate of 0.73 to 0.33 and 0.27 to 0.67. The raw material liquid consisting of
Supply to CSTR and increase the polymerization rate of first stage CSTR from 5 to
The polymerization reaction was carried out to produce a copolymer with a molar fraction of methyl methacrylate of 0.65 to 0.93, and the polymerization rate in the final stage of CSTR was 80% or less. Polymerization is carried out so that there is almost no reacted methyl methacrylate, and the reaction mixture flowing out from the final stage CSTR is distilled in a continuous distillation column, and the separated unreacted monomer (mostly vinyl acetate) is transferred to the final stage CSTR. This is a method of circulating supply and reuse. More preferably in this embodiment, the reaction temperature and residence time of each stage are adjusted so that the molecular weight of the copolymer flowing out from the CSTR of each stage is approximately the same. For this adjustment, it is also an effective means to supply a solution consisting of a polymerization initiator and a solvent to the final stage CSTR. By such an embodiment, acetic acid biacrylic acid having the best properties can be obtained economically, and the reactor has good operability and is easy to control. In the present invention, copolymerizable monomers other than methyl methacrylate and vinyl acetate can be used as necessary. Such copolymerizable monomers include acrylic acid alkyl esters such as butyl acrylate and ethyl acrylate, methacrylic acid alkyl esters other than methyl methacrylate such as butyl methacrylate, methacrylic acid, acrylic acid,
Examples include acidic monomers such as maleic anhydride and basic monomers such as α-vinylpyridine. These monomers are preferably used in amounts such that the molar fraction of these monomers in the copolymer is 0.20 or less. Further, the present invention may be carried out in the presence of an alkyd resin for the purpose of improving the pigment dispersibility of a biacrylic acetate-based paint containing biacrylic acetate as a main component. The alkyd resin is preferably used in an amount of 5% by weight or less based on the copolymer other than the alkyd resin. As the polymerization initiator, those commonly used as polymerization initiators can be used, such as azo compounds such as azobisisobutyronitrile, and peroxides such as benzoyl peroxide. The polymerization initiator is usually used in a proportion of 0.01 to 10% by weight based on the monomer. Further, a chain transfer agent such as tertiarydecyl mercaptan may be used in combination. Further, as the polymerization solvent, aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate, etc. can be used. The polymerization solvent is usually used in an amount of 300% by weight or less based on the monomer. The obtained biacrylic acetate contains pigments such as titanium white,
An extender pigment such as calcium carbonate or barium sulfate can be added to make an enamel paint, or a clear paint can be created without adding extender pigments. As a method for producing enamel paint, known methods such as roll, sand mill, and disperser methods can be used. In addition, so-called paint additives such as pigment dispersants, pigment admixtures, leveling agents, antifoaming agents, etc. may be added to improve the performance and workability of paints. The paint can be applied to mortar, slate, concrete, tiles, etc. for building exteriors by methods such as dipping, brushing, spraying, and rolling. Next, the present invention will be explained using the drawings. FIG. 1 is a schematic diagram showing an example of an apparatus for implementing the present invention. In FIG. 1, a mixture of monomers and polymerization initiator is continuously fed through pipe 1 to CSTR 2. At this time, a solvent may be supplied at the same time if necessary. In CSTR2, the reaction temperature and residence time are controlled to achieve a predetermined polymerization rate. The residence time can be adjusted by changing the feed liquid flow rate, by changing the reactor capacity of the CSTR, or by adjusting the height of pipe 3, which is an overflow pipe, etc. may be changed. The reaction liquid coming out of the CSTR 2 passes through the pipe 3 and is sent to the second stage CSTR 4.
The reaction liquid coming out of the CSTR 4 is sent to a continuous distillation column 6 through a pipe 5. The unreacted monomer separated in the continuous distillation column 6 passes through the pipe 7 to the second stage.
It may be circulated to CSTR4 and reused. The acetic acid biacrylic solution from which unreacted monomers have been removed is transferred to pipe 8.
It is continuously extracted through. In addition, in order to adjust the polymerization rate of the second-stage CSTR4 and the molecular weight of the copolymer produced in the second-stage CSTR4, a mixed solution of a solvent and a polymerization initiator was passed through the pipe 9 to the CSTR4.
4 may be supplied. Furthermore, in order to adjust the molar fraction of the copolymer produced in the second stage CSTR 4, it is also an effective method to supply a portion of the monomer from the pipe 9. Furthermore, by supplying a predetermined amount of solvent from the pipe 10, the nonvolatile content and viscosity of the copolymer solution drawn out through the pipe 8 can be adjusted. FIG. 2 is a schematic diagram showing another apparatus for implementing the present invention. The device shown in FIG. 2 has a three-stage CSTR, which is the device shown in FIG. 1 plus one CSTR connected to the device shown in FIG. In FIG. 2, a mixture of monomers and polymerization initiator is continuously fed to CSTR 12 through pipe 11. At this time, a solvent may be supplied at the same time if necessary. In CSTR12,
The reaction temperature and residence time are controlled to achieve a predetermined polymerization rate. The reaction liquid coming out of the CSTR 12 passes through the pipe 13 and is sent to the second stage CSTR 14. The reaction liquid coming out of the CSTR 14 passes through a pipe 15 and is sent to the third stage CSTR 16. CSTR1
The reaction liquid discharged from 6 is sent to a continuous distillation column 18 through a pipe 17. Unreacted monomers separated in the continuous distillation column 18 may be recycled to the third stage CSTR 16 through a pipe 19 and reused. The acetic acid biacrylic solution from which unreacted monomers have been removed is continuously extracted through a pipe 20. Also,
Polymerization rate of 3rd stage CSTR16 and 3rd stage CSTR
In order to adjust the molecular weight of the copolymer produced in step 16, a mixture of a solvent and a polymerization initiator may be supplied to CSTR 16 through pipe 21. Furthermore, in order to adjust the molar fraction of the copolymer produced in the third stage CSTR 16, it is also an effective method to supply a portion of the monomer from the pipe 21. Furthermore, by supplying a predetermined amount of solvent from the pipe 22, the nonvolatile content and viscosity of the copolymer solution drawn out through the pipe 20 can be adjusted. (Example) Next, the present invention will be explained with reference to Examples, but the present invention is not limited thereto. Parts are by weight. Example 1 Continuous polymerization was carried out using the equipment shown in FIG.
The stirrers of CSTR2 and CSTR4 have upper stages with 45° paddle-shaped blades (CSTR2: blade length 15cm, blade width 3cm, number of blades 4
CSTR4: wingspan 20cm, wingspan 4.5cm, number of sheets 4)
The lower stage is a turbine blade (CSTR2: blade length 15cm, blade width 3cm, number of blades 4, CSTR4: blade length 20cm, blade width 4.5
A two-stage blade consisting of 4 blades (cm, number of blades) was used (rotation speed was 88 rpm in both cases). From pipe 1, 60 parts of vinyl acetate (the mole fraction of raw material monomer components vinyl acetate and methyl methacrylate is vinyl acetate 0.64), 40 parts of methyl methacrylate (the mole fraction of raw material monomer components vinyl acetate and methyl methacrylate is methacrylate) methyl acid 0.36),
Azobisisobutyronitrile 0.35 parts, toluene 25
The liquid consisting of
Supplied to CSTR2. In CSTR2, the heat of polymerization was removed by reflux, and the reaction temperature was controlled at 86°C. In addition, the height of the overflow pipe 3 was adjusted so that the residence time was 2.5 hours.
The reaction solution from CSTR2 overflowed through pipe 3 and was sent to CSTR4, which had a capacity of 50 liters. In addition, in order to make the molecular weight of the copolymer produced in the first stage CSTR2 and the copolymer produced in the second stage CSTR4 almost equal, a liquid consisting of 98 parts of toluene and 2 parts of azobisisobutyronitrile was added to the pipe. 9 was supplied by the second stage CSTR4 at 1 Kg/hr.
In CSTR4, the reaction temperature was controlled at 82°C in the same manner as in CSTR2, in which the heat of polymerization was removed by reflux. Further, the height of the overflow pipe 5 was adjusted so that the residence time was 25 hours. The reaction liquid exiting CSTR 4 overflows through pipe 5, joins with 2 kg/hr of toluene for dilution supplied through pipe 10, and is continuously packed with 1/4-inch McMahon packing with an inner diameter of 100 mm and 50 theoretical plates. The liquid was sent to the distillation column 6. Unreacted monomers are separated in the continuous distillation column 6, and the non-volatile content (hereinafter abbreviated as NV) of 50% and cardner viscosity are separated from the bottom of the column through the pipe 18.
A copolymer solution of Z ₂ was extracted. The unreacted monomers separated in the continuous distillation column 6 were circulated through the pipe 7 to the second stage CSTR 4 at a rate of 4 kg/hr for reuse. The polymerization rates of CSTR2 in the first stage and CSTR4 in the second stage were 40.5% and 50.0%, respectively. In addition, samples sampled from each CSTR were subjected to gel permeation chromatography (hereinafter referred to as
(abbreviated as GPC) to determine the average molecular weight and degree of dispersion in terms of polystyrene. The results are shown in Table 1. The GPC measurement conditions were as follows. [Measurement conditions] Equipment: Hitachi model 635 (manufactured by Hitachi, Ltd.) Column: Three columns connected in series, 10.7 mm in diameter x 30 cm.
Gelpack R440, R450 and R400M for each column
(Product name, manufactured by Hitachi Chemical Co., Ltd.) is used. Column pressure: 35 Kgf/cm ² Flow rate: 2.03 ml/min Detector: Refractive index detector Example 2 Continuous polymerization experiments were conducted using the third-stage CSTR equipment shown in FIG. The stirrers for CSTR12 and CSTR14 are the same as those for CSTR2 in Example 1, and
The stirrer was the same as that of CSTR4 in Example 1.
The capacities of CSTR12, CSTR14 and CSTR16 are 20, 20 and 50, respectively, and the pipe 2
1. The composition and flow rate of the liquid supplied through pipe 11 and pipe 22 were set to be the same as those of pipe 9, pipe 1, and pipe 10 in Example 1, respectively. Pass the pipe 19 through the third CSTR 16,
Unreacted monomers recovered in the continuous distillation column 18 were recycled and reused. Table 2 shows the reaction temperature, residence time, and polymerization rate of each CSTR. From the bottom of the distillation column
A copolymer with NV 50% and Gardner viscosity Z ₂ was obtained.
Further, the average molecular weight and dispersity obtained in the same manner as in Example 1 are shown in Table 2. Comparative Example 1 While introducing _N2 gas into the second reactor equipped with a thermometer and a stirrer, 500 g of toluene and 300 g of vinyl acetate were added.
g (the mole fraction of raw material monomer components vinyl acetate and methyl methacrylate is vinyl acetate 0.64), 200 g of methyl methacrylate (the mole fraction of raw material monomer components vinyl acetate and methyl methacrylate is methyl methacrylate 0.36), and azobis 4 g of isobutyronitrile was added and reacted at 80° C. for 40 hours with stirring to obtain a copolymer solution with NV of 50% and Gardner viscosity of Z ₂ . Comparative Example 2 Synthesis was carried out in the same manner as in Comparative Example 1 except that 2 g of azobisisobutyronitrile was added at the reaction time of 15 hours, and the reaction was carried out for 20 hours with stirring.
A copolymer solution with NV of 50% and Gardner viscosity Z ₁ was obtained. Next, the copolymer solutions that had been reacted to the end in Comparative Row 1 and Comparative Example 2, and the reaction solutions sampled at 15 hours in the middle of the reactions in Comparative Examples 1 and 2 were treated in the same manner as in Example 1. The results of the GPC analysis are shown in Table 3. Comparative Example 3 A continuous polymerization experiment was conducted using the one-stage CSTR equipment shown in FIG. The agitator of CSTR24 used a turbine blade. From pipe 23, 60 parts of vinyl acetate (the mole fraction of raw material monomer components vinyl acetate and methyl methacrylate is vinyl acetate 0.64), 40 parts of methyl methacrylate (the mole fraction of raw material monomer components vinyl acetate and methyl methacrylate is methacrylate) A liquid consisting of 0.36 parts of methyl acid, 0.70 parts of azobisisobutyronitrile, and 25 parts of toluene was supplied to a CSTR 24 with a capacity of 50 at a rate of 5 kg/hr. CSTR24 removed the polymerization heat by refluxing and controlled the reaction temperature to 82°C. Also, pass through the overflow pipe 29 so that the residence time is 5.0 hours,
It was combined with toluene supplied at a rate of Kg/hr and supplied to the continuous distillation column 26. Unreacted monomers separated in the continuous distillation column pass through pipe 27 and are sent to the CSTR.
It was circulated at 4 kg/hr on 24th and reused. NV50% from the bottom of the continuous distillation column 26 through the pipe 28,
It was extracted into a copolymer solution with a Gardner viscosity of _Z2 .
This product was analyzed by GPC in the same manner as in Example 1, and the results are shown in Table 3. Comparative Example 4 A continuous polymerization experiment was conducted using the one-stage CSTR equipment shown in FIG. The agitator of CSTR24 used a turbine blade. From pipe 23, 3 parts of vinyl acetate (mole fraction of vinyl acetate and methyl methacrylate in the raw material monomer component is vinyl acetate 0.03), 97 parts of methyl methacrylate (mole fraction of vinyl acetate and methyl methacrylate in the raw material monomer component) is vinyl acetate
0.97), a solution consisting of 0.70 parts of azobisisobutyronitrile and 25 parts of toluene at a rate of 5 kg/hr.
50 CSTR24 were supplied. CSTR24 removed the polymerization heat by refluxing and controlled the reaction temperature at 82°C. Also, adjust the height of the overflow pipe 25 so that the residence time is 4.0 hours,
The polymerization rate was set to 50%. The reaction liquid overflowing from the pipe 25 passed through the pipe 29, combined with toluene supplied at a rate of 3 kg/hr, and was supplied to the continuous distillation column 26. Unreacted monomers separated in the continuous distillation column pass through pipe 27.
It was circulated and reused in CSTR24 at 4Kg/hr. NV50 is passed from the bottom of the distillation column 26 through the pipe 28.
%, Gardner viscosity Z ₃ copolymer solution was drawn out. This product was analyzed by GPC in the same manner as in Example 1, and the results are shown in Table 3.

【table】

【table】

【table】

[Table] Next, the above Examples 1 and 2 and Comparative Example 1,
The respective copolymer solutions obtained in steps 2, 3, and 4 were separated into two components, a high molecular weight component and a bottom molecular weight component, by GPC, and each of them was subjected to NMR (Hitachi R250 model,
Compositional analysis was performed at Hitachi, Ltd.). (Absorption of -OCH ₃ protons (around 3.6 ppm) of the methyl methacrylate component of the copolymer and vinyl acetate absorption)

Calculated from the integral value of proton absorption (around 2.0 ppm) in [Formula]. The analysis results are shown in Table 4.
The GPC measurement conditions and separation method were as follows. Measurement conditions Equipment: KHD-H1000 type (manufactured by Kyowa Seimitsu Co., Ltd.) Column: Gelpack GL-P50L (Hitachi Chemical Co., Ltd.)
Co., Ltd.) Flow rate: 20 ml/min Sample preparation: A sample was prepared by dissolving 0.3 g of copolymer in 1.5 ml of chloroform Detector: Refractive index detector Classification method The molecular weight distribution was measured under the above measurement conditions. Find the elution volume at which the area on the high molecular weight side of the recorder chart is three times the area on the bottom molecular weight side. Next, the sample is injected again under the same measurement conditions, and at the time when elution is easy, the collection receiver is replaced and the sample is separated into two components: a high molecular weight component and a low molecular weight component. Furthermore, the copolymer solutions produced in the first stage of Examples 1 and 2 and Comparative Examples 3 and 4 were analyzed by NMR.
The composition of the copolymer was analyzed using The results are shown in Table 5.

[Table] The numbers in the table are the content percentages of vinyl acetate components.
(mole fraction).

[Table] The numbers in the table represent the content (mole fraction) of the methyl methacrylate component.
Next, the biacrylic acetate synthesized in Examples 1 and 2 and Comparative Examples 1 to 4 was charged into a 200 ml glass container with the following composition, and applied to a paint shaker for 30 minutes to prepare a seed pen paint. Acetic acid biacrylic titanium white (Ishihara Sangyo R930) Toluene glass beads 60 parts 40 parts 20 parts 100 parts After completion, 60 parts of acetic acid biacrylic was added and the glass beads were separated to obtain a paint with a solid content of 56% by weight. Next, toluene/xylene 50/50 (weight ratio)
The viscosity was determined using an Iwata cup (25°C) using
Diluted to 14 seconds. Apply the diluted paint to ^a slate board (JIS-
A-5403(F)) and used as a test piece plate.
Next, each test piece board was placed at room temperature (20℃).
After drying for 7 days and measuring gloss, water resistance, alkali resistance and weather resistance tests were conducted. The test method and test results are shown in Table 6.

[Table] As shown in Table 4, Examples 1 and 2 of the present invention
The content of the vinyl acetate component as a low molecular weight component of the copolymer synthesized in was almost the same as the content of vinyl acetate component in all components before fractionation, but on the other hand, in Comparative Example 1
In the copolymers synthesized in 2 and 2, the content of vinyl acetate as a low molecular weight component is higher than that of all components before separation, that is, a copolymer with a low molecular weight and high vinyl acetate content is produced. ing. From Table 6, which evaluated paints using these copolymers, Example 1
The paints using the copolymers synthesized in Comparative Examples 1 and 2 had excellent water resistance, alkali resistance, light resistance, and gloss, but the paints using the copolymers synthesized in Comparative Examples 1 and 2 had It was poor in all of the above-mentioned properties, and because it contained a low molecular weight copolymer with a high content of vinyl acetate, it was particularly poor in gloss. Furthermore, as shown in Table 5, Examples 1 and 2 had 1
The mole fraction of methyl methacrylate in the copolymer produced in the CSTR stage was in the range of 0.65 to 0.93, and as mentioned above, the properties of the coating material using it were excellent. On the other hand, the molar fractions of methyl methacrylate in the copolymers synthesized in Comparative Examples 3 and 4 were 0.44 and 0.97, respectively.
Paints using these copolymers outside the range of 0.65 to 0.93 have excellent gloss but poor water resistance, alkali resistance, and weather resistance (Comparative Example 3);
It had excellent alkali resistance and weather resistance, but poor gloss (Comparative Example 4) (Table 6). (Effects of the Invention) The method for producing acetic acid biacrylic copolymer according to the production method of the present invention has excellent productivity, and the resulting paint containing the acetic acid biacrylic copolymer has gloss,
It has excellent water resistance, alkali resistance, and weather resistance.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing one example of the device used to carry out the present invention, FIG. 2 is a schematic diagram showing another example of the device used to carry out the present invention, and FIG. 3 is a comparative example. The schematic diagram showing the apparatus used in and Figure 4 are graphs showing the relationship between the polymerization rate and the molar fraction (instantaneous value) of methyl methacrylate when vinyl acetate and methyl methacrylate are polymerized using one CSTR. It is. Explanation of codes, 1...Pipe, 2...CSTR, 3...
...Pipe, 4...CSTR, 5...Pipe, 6...
Continuous distillation column, 7...pipe, 8...pipe, 9...
...Pipe, 10...Pipe, 11...Pipe, 1
2...CSTR, 13...pipe, 14...
CSTR, 15...Pipe, 16...CSTR, 17
...pipe, 18 ... continuous distillation column, 19 ... pipe, 20 ... pipe, 21 ... pipe, 22 ...
Pipe, 23...Pipe, 24...CSTR, 25
...pipe, 26 ... continuous distillation column, 27 ... pipe, 28 ... pipe, 29 ... pipe.

Claims (1)

[Scope of Claims] 1. Raw monomer components containing vinyl acetate and methyl methacrylate as main components are continuously polymerized in a multi-stage continuous stirred tank reactor in which at least two stirred tanks are connected in series. In the method for producing a vinyl acetate/acrylic copolymer, which removes unreacted monomers, a copolymer having a molar fraction of methyl methacrylate of 0.65 to 0.93 is produced in at least one continuous stirred tank reactor, A method for producing vinyl acetate/acrylic copolymer in which the polymerization rate in the final stage of a continuous stirred tank reactor is 80% or less. 2. Vinyl acetate according to claim 1, wherein the mole fractions of vinyl acetate and methyl methacrylate in the copolymer flowing out from the final stage continuous stirred tank reactor are 0.73 to 0.33 and 0.27 to 0.67, respectively.・Production method of acrylic copolymer. 3. A method for producing a vinyl acetate/acrylic copolymer according to claim 1 or 2, in which unreacted monomers are recycled and reused.