JP5533171B2 - Method for producing saponified ethylene vinyl acetate copolymer resin - Google Patents

Description

  The present invention relates to a method for producing a saponified ethylene vinyl acetate copolymer resin and a method for improving the quality of a saponified ethylene vinyl acetate copolymer resin by setting the water content after drying to 0.25 wt% or less.

  Saponified ethylene vinyl acetate copolymer resin has high weather resistance and excellent airtightness, so it can be used for powder coating of fences and poles, adhesive interlining for clothing, laminated glass intermediate layer, sterile cooked rice tray and frozen food packaging It is used for a wide range of applications such as gas barrier containers.

  Saponified ethylene vinyl acetate copolymer resin (hereinafter abbreviated as saponified EVA) is produced by reacting ethylene vinyl acetate copolymer resin (hereinafter abbreviated as EVA) pellets with caustic soda in methanol. Then, the final product of saponified EVA is manufactured through the steps of neutralization, washing and drying.

  For the final drying, a dryer as shown in FIG. 1 is used.

  From the air inlet (1), by the blower (2), through the heater (3), through each valve (4), from the hot air outlet (5) through the hot air intake mesh (6), to the dryer (7) Supply hot air to

  After the saponified EVA is dried, the hot air is discharged out of the system through a draining mesh (8).

  However, the EVA dust pellets (hereinafter referred to as “fine”) block the hot air intake mesh (6) and the water draining mesh (8) in the hot air intake mesh (6) and the draining mesh (8). The flow path of the saponified EVA is uneven in the dryer, the drying of the saponified EVA is not uniform, the drying unevenness and the moisture content of the saponified EVA increase, and the mesh part of the hot air intake mesh (6) and drained mesh (8) each time In order to eliminate clogging, the entire dryer has to be cleaned, resulting in a long drying time and reduced production efficiency.

  The purpose of the present invention is to shorten the drying time by carrying out various improvements in the method for washing hot air intake mesh (6) and draining mesh (8) when drying saponified EVA with a dryer. At the same time, the water content in the saponified EVA is reduced to improve the quality of the saponified EVA.

  In the present invention, EVA pellets are reacted with caustic soda in methanol at 70 to 90 ° C, neutralized and washed at 40 to 50 ° C using hydrochloric acid methanol solution, washed with water at 40 ° C and dried. A method for producing a saponified EVA, wherein when saponified EVA is dried with a dryer equipped with a hot air intake and a draining mesh, the mesh part of the hot air intake and the mesh part of the draining mesh are washed with a high pressure washer. The cleaning end point is characterized by visually confirming that there is no impurity of saponified EVA in the cleaning liquid discharged from the lower part of the dryer.

  As the water pressure of the high-pressure washing machine, for example, if a water pressure of 5 MPa or more is adopted, it becomes possible to perform washing efficiently.

  For the reaction, neutralization, and washing of the ethylene vinyl acetate copolymer resin pellet with caustic soda in methanol, a conventionally known method can be used.

  When the saponified EVA is dried with a dryer, the following (I) to (III) are carried out in the washing method of the mesh portion of the hot air intake mesh (6) and the drained mesh (8), and the saponified EVA is dried. In addition to reducing the saponified EVA, the water content in the saponified EVA can be reduced to improve the quality of the saponified EVA. The amount of water in the saponified EVA after drying varies depending on the use, but generally needs to be 1.0 wt% or less.

  The drying time of the saponified EVA becomes shorter as the drying temperature becomes higher. However, when the drying temperature is raised, a welding trouble between the pellets occurs. Therefore, the drying process is performed in two stages while keeping the initial drying temperature low. For example, the first stage drying is performed at around 80 ° C. for 5 to 7 hours, and the second stage drying is performed at a temperature 5 to 10 ° C. higher than the first stage for 5 to 7 hours.

The fineness of the mesh is not particularly limited as long as the pellets do not pass through it, but for example, a size of about 10 mesh is sufficient.
(I) The cleaning of the mesh portion of the hot air intake mesh (6) and the draining mesh (8) is changed from the conventional cleaning by the hose sprinkling to the cleaning by the high pressure washer.
(II) The mesh portion of the hot air intake mesh (6) or the draining mesh (8) is washed when the moisture value of the saponified EVA increases by 0.04 to 0.06 wt% immediately after washing the mesh portion.
(III) In addition to confirming that there is no visual fineness of the mesh portion of the hot air intake mesh (6) or the draining mesh (8) as a method for determining the end point of cleaning, fine or the like in the cleaning liquid discharged from the lower part of the dryer Visually confirm that there are no impurities.

  Below, each improvement point is demonstrated in detail.

  Regarding the change of the method for cleaning the mesh part of (I), the conventional hose watering cleaning has a low water pressure and cannot sufficiently remove various impurities such as fines accumulated in the mesh part. In the part of the saponified EVA where a part of the saponified EVA remains after washing and the hot air does not flow through the closed part of the mesh and the hot air does not flow, the drying is not sufficiently achieved, and the drying is temporarily stopped and dried. After the saponified EVA in the machine is taken out, the entire dryer must be cleaned, including the hot air intake mesh (6) and the draining mesh (8).

  Therefore, in the present invention, by changing to a high-pressure washing machine having a high water pressure, various impurities accumulated in the mesh portion are sufficiently removed, and the clogged portion of the mesh portion is completely removed. As a result, the drying time is shortened and the water content in the saponified EVA is reduced to improve the quality of the saponified EVA.

  By washing the entire dryer by stopping the drying operation of (II) when the moisture value of the saponified ethylene vinyl acetate copolymer resin is increased by 0.04 to 0.06 wt% immediately after washing the mesh portion, By sufficiently removing various impurities deposited on the part and completely removing the clogged part of the mesh part, there is no drying unevenness in the washing machine, and not only the drying time is shortened, but also saponified EVA. It is possible to improve the quality of the saponified EVA by reducing the amount of water contained therein.

  The time point at which 0.04 to 0.06 wt% is increased corresponds to cleaning every 7 days in the current plant, and the cleaning frequency is every 7 days.

  In addition to confirming that the cleaning end point of (III) is free of impurities such as fine visual inspection of the mesh portion of the hot air intake mesh (6) and draining mesh (8), in the cleaning liquid discharged from the lower part of the dryer By adding the confirmation that impurities such as fines are not present, drying unevenness in the washing machine is further eliminated and the drying time is shortened, and the water content in the saponified EVA is reduced to reduce the amount of water in the saponified EVA. Quality can be improved.

  The drying method of the saponified EVA of the present invention not only shortens the drying time, but also reduces the amount of water in the saponified EVA, thereby improving the quality of the saponified EVA.

It is a figure which shows the drying method process flow of the saponified EVA of this invention.

  The present invention will be described more specifically by the following examples, but the present invention is not limited to these examples.

Example 1
EVA pellets were reacted with caustic soda in methanol and neutralized and washed to obtain saponified EVA (saponification degree 95%) before drying.

  Thereafter, the following drying was performed.

1200 kg of saponified EVA is supplied to the dryer of (7) in FIG. 1, and hot air of 80 ° C. is passed through the heater (3) by the blower (2) from the air intake port of (1) of FIG. The first drying is carried out for 6 hours by supplying 59 m ³ / min to the dryer (7) through the hot air outlet (5), through the hot air inlet mesh (6), through each valve (4). Then, the temperature of the hot air was raised to 88 ° C., and the second drying was performed for 5 hours. The water content in the saponified EVA after the drying was 0.10 wt%.

  The amount of water increased with the increase in the number of drying batches thereafter, and the amount of water in the saponified EVA after drying after 7 days increased to 0.15 wt%.

  After drying on the 7th day, the impurities accumulated in the hot air intake mesh (6) (10 mesh) and draining mesh (8) (10 mesh) of the dryer are removed from the high pressure washer (Kercher Japan) with a high water pressure of 8 MPa. Washing was carried out until it was confirmed that no impurities were contained in the cleaning liquid from the bottom of the dryer.

  After the washing, when the saponified EVA was similarly dried with a drier, the water content in the saponified EVA after drying returned to 0.10 wt%.

  When the washing every 7 days was carried out three more times, the water content in the saponified EVA returned to 0.10 wt% each time, and the water content in the saponified EVA was maintained at 0.15 wt% or less in all batches. .

  Also, drying in all batches was performed by supplying hot air at 80 ° C. for the first time for 6 hours, and then raising the temperature of the hot air to 88 ° C. for 5 hours for the second time. Drying was performed.

Comparative Example 1
The same saponified EVA as in Example 1 was used as the saponified EVA, and the conventional drying method was performed by using the conventional drying method, watering the hose, and the frequency of washing every 15 days. Carried out.

  1200 kg of saponified EVA is supplied to the dryer of (7) in FIG. 1, and hot air of 80 ° C. is passed through the heater (3) by the blower (2) from the air intake port of (1) of FIG. Each valve (4) is supplied from a hot air outlet (5) through a hot air intake mesh (6) to a dryer (7) and dried for the first time for 6 hours. The temperature was raised to 88 ° C., and the second drying was performed for 9 hours. The water content in the saponified EVA after the drying was 0.10 wt%.

  The amount of water increased due to the increase in the number of subsequent drying batches, and the amount of water in the saponified EVA after drying on the 15th day increased to 0.28 wt%.

  After drying on the 15th day, the impurities accumulated in the hot air intake mesh (6) and the draining mesh (8) of the dryer are washed only with the hose watering, and the hot air intake mesh (6) and the draining mesh of the dryer are washed. In (8), the cleaning was completed only by confirming that various impurities including fines were not visually deposited.

  As a result, in order to keep the water content in the saponified EVA after drying within the specification (0.3 wt% or less), after the first drying with warm air of 80 ° C. for 6 hours, The temperature of the hot air was raised to 88 ° C., and the second drying had to be performed for a long time of 9 hours.

  After the washing, when the saponified EVA was similarly dried with a drier, the water content in the saponified EVA after drying returned to 0.09 wt%, but after drying on the 15th day, it increased to 0.28 wt%. In addition, the entire batch is also dried for the first time with 80 ° C hot air for 6 hours, and then the hot air temperature is raised to 88 ° C for a long time of 9 hours. Otherwise, the water content in the saponified EVA after drying could not be within the specification (0.3 wt% or less).

Example 2
Drying was performed by the following method using saponified EVA (saponification degree: 30%) before drying obtained by the same method as in Example 1.

  1200 kg of saponified EVA is supplied to the dryer of (7) in FIG. 1, and hot air of 55 ° C. is supplied from the air intake port of (1) of FIG. 1 through the heater (3) by the blower (2). Through each valve (4), from the hot air outlet (5), through the hot air intake mesh (6), to the dryer (7), the first drying is performed for 5 hours, and then the temperature of the hot air The temperature was raised to 60 ° C., and the second drying was performed for 7 hours. The water content in the saponified EVA after the drying was 0.06 wt%.

  The amount of water increased due to the increase in the number of subsequent drying batches, and the amount of water in the saponified EVA after drying on the seventh day increased to 0.10 wt%.

  After drying on the 7th day, the water pressure is as high as 8 MPa for various impurities such as fine accumulated on the hot air intake mesh (6) (10 mesh) and the draining mesh (8) (10 mesh) of the dryer. Using a high pressure washer (manufactured by Kercher Japan, HD4 / 8C type), it was sufficiently removed and washed from the bottom of the dryer until no impurities were contained in the washing solution.

  After the washing, when the saponified EVA was similarly dried with a drier, the water content in the saponified EVA after drying returned to 0.06 wt%.

  When the 7-day cleaning was performed three more times, the water content in the saponified EVA returned to 0.06 wt% each time, and the water content in the saponified EVA was maintained at 0.10 wt% or less in all batches. It was.

  Also, drying in all batches was conducted by sending hot air at 55 ° C. for the first time for 5 hours, and then raising the temperature of the hot air to 60 ° C. for 7 hours for the second time. Drying was performed.

Comparative Example 2
The same saponified EVA as in Example 2 was used as the saponified EVA, and the conventional drying method with the conventional drying method, hose watering, the frequency of washing every 15 days, and the method of determining the washing end point was only confirmed inside the dryer. It was conducted.

  1200 kg of saponified EVA is supplied to the dryer of (7) in FIG. 1, and hot air of 55 ° C. is supplied from the air intake port of (1) of FIG. 1 through the heater (3) by the blower (2). Through each valve (4), from the hot air outlet (5), through the hot air intake mesh (6), to the dryer (7), the first drying is performed for 5 hours, and then the temperature of the hot air Was raised to 60 ° C. and a second drying was carried out for 11 hours. The water content in the saponified EVA after the drying was 0.05 wt%.

  The amount of water increased with the increase in the number of drying batches thereafter, and the amount of water in the saponified EVA after the 15th day of drying increased to 0.15 wt%.

  After drying on the 15th day, the impurities accumulated in the hot air intake mesh (6) and the draining mesh (8) of the dryer are washed only with the hose watering, and the hot air intake mesh (6) and the draining mesh of the dryer are washed. Cleaning was completed only by confirming that no impurities were visually deposited in (8).

  As a result, in order to keep the water content in the saponified EVA after drying within the specification (0.3 wt% or less), the first drying with hot air at 55 ° C. was performed for 5 hours, The temperature of the hot air was raised to 60 ° C., and the second drying had to be performed for a long time of 11 hours.

  After the washing, when the saponified EVA was similarly dried with a dryer, the water content in the saponified EVA after drying returned to 0.05 wt%, but after 30 batches of drying, it increased to 0.15 wt%. In addition, drying of all the batches was carried out for 5 hours after the first drying of hot air at 55 ° C. for 5 hours, and then the temperature of the hot air was raised to 60 ° C. Otherwise, the water content in the saponified EVA after drying could not be within the specification (0.3 wt% or less).

Example 3
Using the saponified EVA (saponification degree 80%) before drying obtained by the same method as in Example 1, it was dried by the following method.

  1200 kg of saponified EVA is supplied to the dryer of (7) in FIG. 1, and hot air of 78 ° C. is blown from the air intake port of (1) of FIG. 1 through the heater (3) by the blower (2). Through each valve (4), from the hot air outlet (5), through the hot air intake mesh (6), to the dryer (7), the first drying is performed for 5 hours, and then the temperature of the hot air Was raised to 83 ° C. and a second drying was carried out for 5 hours. The water content in the saponified EVA after the drying was 0.20 wt%.

  The amount of water increased with the increase in the number of subsequent drying batches, and the amount of water in the saponified EVA after drying on the seventh day increased to 0.24 wt%.

  After drying on the 7th day, various impurities such as fine deposits accumulated on the hot air intake mesh (6) and draining mesh (8) of the dryer, a high pressure washer with a high water pressure of 8 MPa (manufactured by Kercher Japan) , HD4 / 8C type) was sufficiently removed and cleaning was performed from the bottom of the dryer until no impurities were contained in the cleaning liquid.

  After the washing, when the saponified EVA was similarly dried with a drier, the water content in the saponified EVA after drying returned to 0.20 wt%.

  When the 15 batches were further washed three times, the water content in the saponified EVA returned to 0.20 wt% each time, and the water content in the saponified EVA was maintained at 0.24 wt% or less in all batches. It was.

  In addition, drying of all batches is also performed by sending hot air at 78 ° C for the first time for 5 hours, and then raising the temperature of the hot air to 83 ° C for the second time for 5 hours. Drying was performed.

Comparative Example 3
The same saponified EVA as in Example 3 was used as the saponified EVA, and the conventional drying method with the conventional drying method, hose watering, the frequency of washing every 15 days, and the method for determining the end point of washing was only confirmed inside the dryer. It was conducted.

  1200 kg of saponified EVA is supplied to the dryer of (7) in FIG. 1, and hot air of 78 ° C. is blown from the air intake port of (1) of FIG. 1 through the heater (3) by the blower (2). Each valve (4) is supplied from a hot air outlet (5) through a hot air intake mesh (6) to a dryer (7) and dried for the first time for 6 hours. Was raised to 83 ° C. and a second drying was carried out for 8 hours. The water content in the saponified EVA after the drying was 0.14 wt%.

  The amount of water increased due to an increase in the number of subsequent drying batches, and the amount of water in the saponified EVA after drying on the 15th day increased to 0.34 wt%.

  After drying on the 15th day, various impurities such as fines accumulated on the hot air intake mesh (6) and the draining mesh (8) of the dryer are washed only with the hose watering, and the hot air intake mesh of the dryer Cleaning was completed only by confirming that no impurities were visually deposited on (6) or the draining mesh (8).

  As a result, in order to keep the water content in the saponified EVA after drying within the specification (1.0 wt% or less), the first drying with hot air at 78 ° C. was performed for 5 hours, The temperature of the hot air was raised to 83 ° C. and the second drying had to be performed for a long time of 8 hours.

  After the washing, when the saponified EVA was similarly dried with a drier, the water content in the saponified EVA after drying returned to 0.14 wt%, but after 30 batches of drying, it increased to 0.34 wt%. In addition, drying of all the batches was performed for 5 hours after the first drying of hot air at 78 ° C. for 5 hours, and then the temperature of the hot air was increased to 83 ° C. and drying was performed for a long time of 8 hours. Otherwise, the water content in the saponified EVA after drying could not be within the specification (1.0 wt% or less).

  The production method of the saponified ethylene vinyl acetate copolymer resin of the present application makes it possible to shorten the drying time, and can control the amount of water in the saponified ethylene vinyl acetate copolymer resin after drying to reduce the amount of industrial saponified ethylene. It can utilize for the manufacturing method of vinyl acetate copolymer resin.

1: Air intake 2: Blower 3: Heater 4: Each valve 5: Hot air outlet 6: Hot air intake mesh 7: Dryer 8: Draining mesh

Claims (2)

A method for producing a saponified ethylene vinyl acetate copolymer resin, wherein the pellets of ethylene vinyl acetate copolymer resin are reacted with caustic soda in methanol and then neutralized, washed and dried. When drying with a dryer equipped with an intake port and a draining mesh, the mesh part of the hot air intake port and the mesh part of the draining mesh are washed with a high-pressure washing machine with a water pressure of 5 MPa or more. A method for producing a saponified ethylene-vinyl acetate copolymer resin characterized by visually confirming that there is no impurity in the cleaning liquid discharged from the water. The saponified ethylene vinyl acetate copolymer resin according to claim 1, wherein the mesh portion is washed when the moisture value of the saponified ethylene vinyl acetate copolymer resin is increased by 0.04 to 0.06 wt% immediately after washing the mesh portion. Manufacturing method.

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