JP4938432B2 - Continuous production method of cured acrylic resin - Google Patents

Description

  The present invention relates to a method for continuously producing a cured acrylic resin. More specifically, the present invention relates to a method for continuously producing a cured acrylic resin product having a good quality by a simple method with high energy efficiency and high productivity using a simple apparatus.

  As a method for producing a plate-like body by polymerizing and curing an acrylic polymerizable composition, a batch method using a mold and a continuous method for continuously producing a plate-like body by polymerizing and curing in a continuous plate-like space are known. It has been. As a batch method using a mold, a gasket (mold) is formed by inserting a gasket between two metal plates or glass plates and press-bonding with a clamp, and an acrylic polymerizable composition is injected into the mold In general, a method of polymerizing and curing in a water tank or an air circulation oven and then disassembling the mold and taking out a plate-shaped polymerized cured product is generally employed (see, for example, Patent Document 1). However, the batch method using a mold has problems that the operation is complicated, the productivity is very low, and the cost is high.

In addition, as a method of continuously producing a plate-like acrylic resin cured product, a continuous curing device composed of an endless belt and an auxiliary device is used for a methyl methacrylate monomer mixture or an acrylic resin artificial marble plate. A method of continuously producing a plate-like product by continuously injecting an acrylic polymerizable composition such as a polymerization raw material mixture and polymerizing and curing as the endless belt moves is known (Patent Documents 2 and 2). 4).
However, in the conventional method for continuously producing a plate-like acrylic resin cured product described above, in order to polymerize and cure the acrylic polymerizable composition, a heating device and a cooling device are provided along the movement path of the acrylic polymerizable composition. The temperature at the time of polymerization and curing can be set up by dividing the air-curing type curing chamber into multiple areas (rooms), and individually providing a blower, heater, circulation duct, nozzle unit, etc. in each area (room). A method of making individual adjustments is adopted. For this reason, the facilities are complicated and costly. Moreover, in the case of such a conventional method for continuously producing a cured acrylic resin, depending on the brand to be produced, the production amount, etc., each heating device, cooling device, heating conditions for each room or area, etc. Because it is necessary to individually adjust so that the curing on the upper and lower surfaces of the plate-shaped body is performed uniformly, it takes a lot of time and effort when changing brands or changing manufacturing conditions, and it is complicated. Requires skill. In addition, since the heating and cooling zones are separated, the heat exchanger in the heating zone always needs to be heated, while the heat exchanger in the cooling zone always cools the polymerization heat generated by the polymerization reaction. There is a drawback that the opposite process must always be performed in the adjacent area and the energy efficiency is very poor.

JP-A-53-112990 U.S. Pat. No. 4,133,861 Japanese Patent Publication No. 47-34815 JP-A-10-217264 "Organic peroxide general catalog (10th edition) General properties, action and application, selection, analysis method", 1-5 (Table 1), published by Nippon Oils and Fats, 2003

  An object of the present invention is to install a heating device and a cooling device in a plurality of stages, or to divide an air circulation type chamber into a plurality of areas (rooms) and to supply a fan, a heater, a circulation duct, and a nozzle unit in each area (room). Without using complicated and expensive equipment such as individually, etc., using a simple manufacturing equipment, continuous high-quality acrylic resin cured products with improved energy efficiency and high productivity It is to provide a method of manufacturing automatically.

  The present inventors have intensively studied to achieve the above-described object. As a result, while continuously supplying the acrylic polymerizable composition to one hot-air circulating heating furnace not partitioned into a plurality of zones (chambers) and continuously moving in the hot-air circulating heating furnace It has a 10-hour half-life temperature that is 10 to 60 ° C. lower than the temperature of hot air introduced into the hot air circulating heating furnace as a thermal polymerization initiator for polymerizing and curing the acrylic polymerizable composition at that time. When a specific thermal polymerization initiator is used, polymerization curing is sufficiently performed while the acrylic polymerizable composition continuously moves in the hot-air circulating heating furnace, and curing of the acrylic resin with good quality is achieved. It was found that a product was obtained.

  In addition, the present inventors continuously supply an acrylic polymerizable composition to the above-described hot air circulation type heating furnace that is not partitioned into a plurality of zones (chambers) to produce an acrylic resin cured product, From the time when the acrylic polymerizable composition reaches the inlet of the hot-air circulating heating furnace, the temperature of the acrylic polymerizable composition or its polymerized cured product reaches the same temperature as the hot air introduced into the hot-air circulating heating furnace. Until the temperature of the acrylic polymerizable composition or the temperature of the polymerized cured product reaches the same temperature as the temperature of the hot air introduced into the hot-air circulating heating furnace, the polymerization cured product exits from the hot-air circulating heating furnace. It has been found that when the acrylic polymerizable composition is polymerized and cured such that the ratio to the time to reach a specific range is within a specific range, the acrylic polymerizable composition can be polymerized and cured more smoothly. .

  Furthermore, the present inventors circulate hot air in the hot air circulation heating furnace, that is, hot air circulation type in introducing hot air into the hot air circulation heating furnace and taking out gas (hot air) from the hot air circulation heating furnace. Extraction of gas (hot air) from the heating furnace is performed from a plurality of specific locations in the hot air circulation heating furnace, and the gas (hot air) extracted from the plurality of locations is mixed and then introduced into the hot air circulation heating furnace When the temperature is adjusted and recirculated (re-introduced) to the hot air circulation heating furnace, the heat of the gas (hot air) taken out from the hot air circulation heating furnace can be effectively reused without waste, and extremely high thermal energy efficiency Thus, it was found that the acrylic resin cured product can be continuously produced, and the present invention was completed based on these various findings.

That is, the present invention
(1) An acrylic polymerizable composition containing an unsaturated monomer mainly composed of methyl methacrylate and a thermal polymerization initiator is supplied to a molding space that continuously moves forward in a hot-air circulating heating furnace. A method of continuously producing an acrylic resin cured product by polymerization and curing, wherein the thermal polymerization initiator is 10 to 60 ° C. higher than the temperature (Ta) (° C.) of hot air introduced into a hot air circulating heating furnace. A method for continuously producing a cured acrylic resin, characterized by using a thermal polymerization initiator having a low 10-hour half-life temperature.

And this invention,
(2) The continuous production method of the above (1), wherein the temperature (Ta) (° C.) of the hot air introduced into the hot air circulation heating furnace is a constant temperature in the range of 30 to 120 ° C .;
(3) The atmospheric temperature (Tb) (° C.) in the hot air circulation heating furnace is changed to [temperature of hot air introduced into the hot air circulation heating furnace (Ta) (° C.) − 10 (° C.)] and [hot air circulation type The continuous production method of the above (1) or (2), which is maintained at a temperature within the range of the temperature of hot air introduced into the heating furnace (Ta) (° C.) + 10 (° C.)]; and
(4) When the acrylic polymerizable composition reaches the inlet of the hot air circulation type heating furnace, the temperature of the hot air introduced into the hot air circulation type heating furnace (Ta ) The time to reach the same temperature as (° C.) is (A), and the temperature of the hot air introduced into the hot air circulation furnace (Ta) (° C.) When the time from when the temperature reaches the same temperature until the polymerization cured product reaches the outlet of the hot-air circulating heating furnace is (B), (A) / (B) = 1-3 A continuous production method according to any one of the above (1) to (3), wherein the acrylic polymerizable composition is polymerized and cured in a hot-air circulating heating furnace;
It is.

Furthermore, the present invention provides
(5) Until the product temperature of the inlet of the hot air circulation heating furnace and the acrylic polymerizable composition or its polymerized cured product reaches the same temperature as the temperature (Ta) (° C) of the hot air introduced into the hot air circulation heating furnace _A gas take-out part from the hot air circulation heating furnace is provided in the area (E _A ), and the temperature of the hot air introduced into the hot air circulation heating furnace (Ta) ) A gas extraction part from the hot air circulation heating furnace is provided in an area (E _B ) between the point where the temperature reaches the same temperature as (° C.) and the exit of the hot air circulation heating furnace, and the area (E _A ) and the area (E _B ) The gas extracted from the gas extraction part provided in each of the above is mixed into a mixed gas, and the mixed gas is adjusted to the temperature (Ta) (° C) of hot air introduced into the hot-air circulating heating furnace to circulate hot air (1) to (4) Any continuous production method;
(6) The temperature (T _mix ) (° C) of the mixed gas obtained by mixing the gas extracted from the gas extraction section provided in each of the section (E _A ) and the section (E _B ), and the hot-air circulating furnace The continuous production method of the above (5), wherein the difference from the temperature (Ta) (° C) of the hot air to be introduced is 5 ° C or less;
(7) The continuous production method according to any one of (1) to (6), wherein the acrylic polymerizable composition is an acrylic polymerizable composition for producing an acrylic resin-based artificial marble further containing an inorganic powder; and ,
(8) The continuous production method according to any one of (1) to (7), wherein a plate-like acrylic resin cured product is produced;
It is.

In the case of the method of the present invention, a hot air circulation type heating furnace that is not partitioned into a plurality of chambers and has a very simple structure is used as a heating device for polymerizing and curing an acrylic polymerizable composition, and a complicated temperature is used. Without requiring management or temperature control, it is possible to produce an acrylic resin cured product having a sufficient quality that is sufficiently cured by polymerization and having a good quality, with high productivity.
Furthermore, in the present invention, the temperature of the acrylic polymerizable composition or the polymerization cured product thereof is introduced into the hot air circulating heating furnace from the time when the acrylic polymerizable composition reaches the inlet of the hot air circulating heating furnace. The time A until reaching the same temperature as the temperature (Ta) (° C.), and the temperature of the hot air introduced into the hot-air circulating heating furnace (Ta) (° C.) by the product temperature of the acrylic polymerizable composition or its polymerized cured product By adopting a condition in which the ratio (A / B) to the time B until the polymerized cured product reaches the outlet of the hot-air circulating heating furnace from the point of time when the temperature reaches the same temperature as in the range from 1 to 3, Polymerization and curing of the system polymerizable composition can be performed more smoothly.

In the present invention, the temperature of the hot air circulating heating furnace and the temperature of the acrylic polymerizable composition or the polymerized cured product thereof are the same as the temperature (Ta) (° C.) of hot air introduced into the hot air circulating heating furnace. The temperature until reaching (E _A ) (previous stage) and the temperature of the acrylic polymerizable composition or its polymerized cured product is the same as the temperature (Ta) (° C.) of the hot air introduced into the hot air circulating furnace Gas extraction parts from the hot air circulation heating furnace are provided in both the area (E _B ) (rear stage area) between the point where the temperature has been reached and the outlet of the hot air circulation heating furnace, respectively, The gas taken out from the gas take-out part provided in the above is mixed to make a mixed gas, and the mixed gas is adjusted to the hot air temperature (Ta) (° C.) to be introduced into the hot air circulation heating furnace, and then into the hot air circulation heating furnace by recycling, zone convection oven (E _B) Subsequent zone) by effectively reused without waste heat of high temperature hot air generated (gas), in a very high energy efficiency, it is possible to continuously and economically producing an acrylic resin cured product.
According to the method of the present invention, any of acrylic resin-based artificial marble, artificial granite, and other cured acrylic resins can be produced smoothly and with good productivity. In particular, the method of the present invention is an acrylic resin having a plate shape. It is effective for the production of cured resin.

The present invention is described in detail below.
The present invention supplies an acrylic polymerizable composition containing an unsaturated monomer mainly composed of methyl methacrylate and a thermal polymerization initiator to a molding space that continuously moves forward in a hot-air circulating heating furnace. This is a continuous process for producing a cured acrylic resin that is polymerized and cured into an acrylic resin cured product while moving in a hot air circulating heating furnace, and the acrylic resin cured product is continuously removed from the heated air circulating heating furnace. is there.
The "hot air circulation type heating furnace" used in the present invention continuously introduces hot air of a predetermined temperature into the furnace, and at the same time continuously removes gas from the furnace, thereby circulating hot air in the furnace, It refers to a heating furnace in which the atmospheric temperature in the furnace is maintained at or close to the temperature of hot air introduced into the furnace.
The internal space of the hot air circulation type heating furnace used in the present invention is not partitioned into a plurality of chambers, and the acrylic polymerizable composition enters the hot air circulation type heating furnace from the inlet portion where the hot air circulation type heating furnace enters. One continuous space (heating chamber) is formed up to the exit portion where the cured acrylic resin produced by polymerization and curing is taken out.

In the present invention, hot air adjusted to a predetermined temperature (Ta) (° C.) is introduced (blown) into a hot air circulation type heating furnace composed of one continuous space (heating chamber), and the hot air circulation type heating is performed. The gas (hot air) in the hot air circulating heating furnace (space) is taken out from a predetermined place of the furnace, and after the temperature of the extracted gas is adjusted to the temperature (Ta), it is reintroduced into the hot air circulating heating furnace.
The acrylic polymerizable composition continuously supplied to the hot air circulating heating furnace is moved (advanced) continuously in the hot air circulating heating furnace by the hot air circulating in the hot air circulating heating furnace. Polymerized and cured to obtain a cured acrylic resin.

In the present invention, in the continuous production of the acrylic resin cured product by the method described above, the temperature of the hot air (Ta) introduced into the hot air circulation heating furnace as the thermal polymerization initiator to be contained in the acrylic polymerizable composition. ) A thermal polymerization initiator having a 10-hour half-life temperature that is 10 to 60 ° C. lower than (° C.) is used. That is, in the present invention, a thermal polymerization initiator having a 10-hour half-life temperature within the range of [Ta-60 (° C.)] to [Ta-10 (° C.)] is used.
By using a thermal polymerization initiator having a 10-hour half-life temperature that is 10-60 ° C. lower than the temperature (Ta) (° C.) of the hot air introduced into the hot-air circulating heating furnace as the thermal polymerization initiator, an acrylic resin Fully polymerized and cured without causing a decrease in the polymerization curing rate of the cured product, poor control of the polymerization and curing reaction, foaming and physical properties in the resulting acrylic resin cured product, and a decrease in productivity due to slow polymerization curing. Thus, a cured acrylic resin having excellent physical properties and appearance can be continuously produced with high productivity.

If the 10-hour half-life temperature of the thermal polymerization initiator contained in the acrylic polymerizable composition is higher than [Ta-10 (° C.)], the decomposition temperature of the thermal polymerization initiator becomes too high, and hot air circulation occurs. Since the thermal decomposition rate of the thermal polymerization initiator in the heating furnace becomes slow and a long time is required for the polymerization and curing, the acrylic resin cured product cannot be continuously produced with high productivity. On the other hand, when the 10-hour half-life temperature of the thermal polymerization initiator is lower than [Ta-60 (° C.)], the thermal polymerization initiator is easily decomposed at a low temperature, and the thermal polymerization initiator and an acrylic type containing the thermal polymerization initiator Not only is the storage and handling of the polymerizable composition difficult, the thermal decomposition of the thermal polymerization initiator proceeds rapidly in the hot air circulating heating furnace, foaming occurs in the cured acrylic resin, and the polymerization curing is sufficient. Will not be done.
In the present invention, as the thermal polymerization initiator, it is preferable to use a thermal polymerization initiator having a 10-hour half-life temperature that is 15 to 50 ° C. lower than the temperature (Ta) (° C.) of the hot air introduced into the hot-air circulating heating furnace. It is more preferable to use a thermal polymerization initiator having a 10-hour half-life temperature that is 20 to 40 ° C. lower than the temperature (Ta) (° C.) of the hot air.

As used herein, “10-hour half-life temperature of thermal polymerization initiator” refers to a temperature at which the thermal polymerization initiator molecule is thermally decomposed and reduced to the original half after 10 hours. That is, at the same polymerization temperature, the higher the 10-hour half-life temperature, the slower the decomposition rate and the slower the polymerization reaction rate.
The “10-hour half-life temperature of the thermal polymerization initiator” has already been described in various documents and is known. In the present invention, the “10-hour half-life of the thermal polymerization initiator” is described in Non-Patent Document 1. Based on the value of the “period temperature”, the difference between the temperature (Ta) (° C.) of the hot air introduced into the hot-air circulating heating furnace and the 10-hour half-life temperature of the thermal polymerization initiator is determined, and the 10-hour half-life temperature is the hot air The thing of 10-60 degreeC lower than the temperature (Ta) (degreeC) of the hot air introduce | transduced into a circulation type heating furnace, Preferably the thing 15-50 degreeC lower, More preferably, the thing 20-40 degreeC lower is used.

In the acrylic polymerizable composition used in the present invention, only one kind of thermal polymerization initiator having a 10-hour half-life temperature within the above-mentioned range defined in the present invention may be used, or two or more kinds may be used. You may use it in combination.
In some cases, a thermal polymerization initiator having a 10-hour half-life temperature within the range defined in the present invention and a thermal polymerization initiator having a 10-hour half-life temperature outside the range defined by the present invention are included. It can also be used in combination.

  The content of the thermal polymerization initiator in the acrylic polymerizable composition is such that all unsaturated monomers mainly composed of methyl methacrylate contained in the acrylic polymerizable composition are contained in order to facilitate the polymerization and curing reaction. Usually, it is preferably 0.01 to 3% by mass, and more preferably 0.03 to 2% by mass based on the mass.

The temperature of the hot air introduced into the hot air circulation heating furnace is the composition of the acrylic polymerizable composition, the moving speed of the acrylic polymerizable composition or the cured acrylic resin in the hot air circulation heating furnace, the hot air circulation heating. Depending on the scale of the furnace, the thickness and width of the cured acrylic resin to be produced, the pattern, etc., the acrylic resin can be smoothly and sufficiently polymerized and cured, the acrylic resin In view of productivity of the cured product, the temperature is preferably within a range of 30 to 120 ° C, and more preferably within a range of 40 to 90 ° C.
The temperature of the hot air introduced into the hot air circulation heating furnace is preferably a constant temperature within the above-mentioned temperature range from the viewpoint that the atmosphere temperature in the hot air circulation heating furnace can be controlled smoothly and easily.

The atmospheric temperature in the hot air circulating heating furnace is determined by the heat absorption by the acrylic polymerizable composition in the initial stage supplied to the hot air circulating heating furnace, the heat generated by the decomposition or polymerization of the thermal polymerization initiator, etc. The temperature is not necessarily completely the same over the entire region in the circulating heating furnace. In the present invention, the atmospheric temperature (Tb) (° C.) in the entire region in the hot air circulation heating furnace is set as [temperature of hot air introduced into the hot air circulation heating furnace (Ta) (° C.) − 10 (° C.)], It is preferable to maintain the temperature within the range of [temperature of hot air introduced into hot air circulating heating furnace (Ta) (° C.) + 10 (° C.)], and [temperature of hot air introduced into hot air circulating heating furnace (Ta) (° C.) − 5 (° C.)] and [temperature of hot air introduced into the hot air circulating heating furnace (Ta) (° C.) + 5 (° C.)] are more preferably maintained.
By maintaining the atmospheric temperature in the entire region in the hot-air circulating heating furnace within the above-mentioned temperature range, the polymerization and curing of the acrylic polymerizable composition is smoothly performed without unevenness, and a high-quality acrylic resin cured product is obtained. Obtainable.
As a method of maintaining the atmospheric temperature in the entire region in the hot air circulation heating furnace in the above-described temperature range, for example, a plurality of locations of the hot air circulation heating furnace according to the distribution state of the atmospheric temperature in the hot air circulation heating furnace The hot air circulating heating furnace is provided with a hot air circulating heating furnace at a plurality of locations in the hot air circulating heating furnace. And a method of circulating hot air, a method of controlling the amount of hot air introduced into the hot air circulation heating furnace, a gas extraction amount from the hot air circulation heating furnace, a method of combining them, and the like.

When the acrylic resin cured product is continuously produced according to the method of the present invention, the product temperature of the acrylic polymerizable composition and the acrylic resin cured product in the hot air circulating heating furnace is generally as shown in FIG. It becomes temperature history.
More specifically, as shown in FIG. 1, the acrylic polymerizable composition continuously supplied from the inlet of the hot air circulating heating furnace has a hot air circulating heating furnace as it advances through the hot air circulating heating furnace. The product temperature is gradually increased by the heated gas (hot air) inside and reaches the temperature (Ta) (° C) of the hot air introduced into the hot-air circulating heating furnace. Since the thermal polymerization initiator is decomposed and polymerization curing proceeds to generate heat of polymerization, the product temperature of the acrylic polymerizable composition or acrylic resin cured product is the temperature of the hot air introduced into the hot air circulating heating furnace ( The atmospheric temperature of the hot air circulation heating furnace reaches a higher peak temperature, and then the product temperature of the cured acrylic resin is gradually lowered to a temperature lower than the lower limit of the atmospheric temperature in the hot air circulation heating furnace. Reach the exit of the furnace.

In the present invention, the temperature of the hot air introduced into the hot air circulation heating furnace from the time when the acrylic polymerizable composition reaches the inlet of the hot air circulation heating furnace, the product temperature of the acrylic polymerizable composition or its polymerized cured product. (Ta) The time required to reach the same temperature as (° C.) is (A), and the temperature of the hot air introduced into the hot air circulation heating furnace (Ta) (Ta) ( (A) / (B) = 1 to 3 [i.e., (B), where (B) is the time from when the temperature reaches the same temperature as when the polymerization cured product reaches the outlet of the hot-air circulating heating furnace. It is preferable to carry out the polymerization and curing so that the time of A) is 1 to 3 times the time of (B), and (A) / (B) = 1.5 to 2 [(A) is (B) It is more preferable to carry out the polymerization and curing so as to be 1.5 to 2 times larger than the above.
By setting the ratio of the time lengths (A) and (B) [(A) / (B)] to the above-described range, the cured acrylic resin is sufficiently polymerized and cured and has excellent physical properties and appearance. Can be manufactured with good productivity while maintaining good thermal energy efficiency.
In order to set the ratio of the length of time (A) and (B) [(A) / (B)] to the above-mentioned range, the kind of thermal polymerization initiator contained in the acrylic polymerizable composition ( 10-hour half-life temperature), its blending amount, the temperature of the hot air introduced into the hot air circulation heating furnace, the ambient temperature in the hot air circulation heating furnace, the acrylic polymerizable composition and the acrylic in the hot air circulation heating furnace The moving speed of the cured resin may be adjusted.

If the ratio of (A) / (B) described above deviates from the above range and the time corresponding to (A) becomes too long, the temperature rise in the hot air circulating heating furnace and the progress of the polymerization are slow and the productivity is increased. In addition, since the curability due to the polymerization initiator is poor, post-cure is necessary in a later step. Moreover, since the time corresponding to (B) is relatively short, the ambient temperature in the region corresponding to (B) in the hot-air circulating heating furnace is lowered, and the gas taken out from the region corresponding to (B) A large amount of heat energy is required to heat the gas to the temperature (Ta) (° C.) when the hot air is heated to the temperature (Ta) (° C.) and recirculated to the hot air circulation heating furnace.
On the other hand, if the ratio of (A) / (B) is out of the above range and the time corresponding to (A) becomes too short, the acrylic polymerizable composition or the cured acrylic resin reaches the peak temperature. Despite the completion of the reaction, the residence time (cooling time) in the hot air circulating heating furnace is taken longer than necessary, and the productivity of the cured acrylic resin is likely to be lowered.
As used herein, “the product temperature of the acrylic polymerizable composition or the cured acrylic resin” refers to the temperature of the acrylic polymerizable composition itself or the cured acrylic resin itself. It can obtain | require by measuring the temperature of the center part of an adhesive composition or acrylic resin hardened | cured material. For example, when the acrylic polymerizable composition or the acrylic resin cured product is a continuous plate-like product having a square cross section, the intersection of two diagonal lines in the cross section forming the square is the center. What is necessary is just to measure the temperature of an intersection part as center temperature.

In the continuous production method of the cured acrylic resin of the present invention, the acrylic polymerizable composition is supplied from the inlet of the hot air circulation type heating furnace, polymerized and cured as an acrylic resin cured product from the outlet of the hot air circulation type heating furnace. The time until removal [the total time of (A) and (B) described above] is the composition of the acrylic polymerizable composition, the size and shape of the cured acrylic resin to be produced, the brand, and the hot air circulation heating furnace. The temperature of the hot air to be introduced, the atmospheric temperature in the hot air circulation heating furnace, the moving speed of the acrylic polymerizable composition and the cured acrylic resin in the hot air circulation heating furnace, and casting the acrylic polymerizable composition Although it may vary depending on the molding space (a container in which an acrylic polymerizable composition is placed), it is generally 20 to 100 minutes, particularly 30 to 60 in terms of the quality and productivity of the resulting cured acrylic resin. It is preferable that a degree.
Moreover, the moving speed (advance speed) of the acrylic polymerizable composition and the cured acrylic resin in the hot air circulating heating furnace is usually 0.05 to 2 m / min, particularly about 0.1 to 1 m / min. It is preferable for the acrylic polymerizable composition to be sufficiently and smoothly polymerized and cured.

In carrying out the method of the present invention, the hot air circulation system in the hot air circulation heating furnace is not particularly limited, and the temperature difference of the ambient temperature in the entire region in the hot air circulation heating furnace can be kept as small as possible. Any method may be employed as long as the heat energy efficiency for hot air circulation in the hot air circulation heating furnace can be kept as high as possible.
In particular, the area between the up product temperature convection inlet and an acrylic polymerizable composition of the furnace or a cured polymer reaches the same temperature as the temperature of the hot air introduced into the hot air circulation type heating furnace (E _A) [Area corresponding to the time of (A) described above] is provided with a gas take-out part from the hot air circulation heating furnace, and the temperature of the acrylic polymerizable composition or its polymerized cured product is introduced into the hot air circulation heating furnace. Gas from the hot air circulating heating furnace in the area (E _B ) [the area corresponding to the time of (B) described above] between the point where the temperature reaches the same temperature as the hot air temperature and the outlet of the hot air circulating heating furnace The temperature of the hot air which mixes the gas taken out from the gas extraction part provided in each of the section (E _A ) and the section (E _B ) into a mixed gas and introduces the mixed gas into the hot-air circulating heating furnace (Ta) temperature control and hot air circulation Method for introducing into the furnace is preferably used. By adopting such a method, the area reduced gas [general hot air introduced into the hot air circulation type heating furnace temperature of the temperature taken from the gas take-out section in the _{(E A) (Ta) (} ℃) cold gas than ] Is heated by a high-temperature gas extracted from the gas extraction section in the section (E _B ) [generally, a gas having a temperature higher than the temperature (Ta) of the hot air introduced into the hot-air circulating heating furnace]. The temperature (T _mix ) (° C.) of the mixed gas obtained by mixing the gas is very close to the temperature (Ta) of the hot air introduced into the hot air circulation heating furnace, and the mixed gas is used as the hot air circulation heating furnace. The heat energy required to heat and adjust the temperature until reaching the temperature (Ta) to be introduced (circulated) into the heat exchanger is very small, and the heat energy efficiency is extremely high.

In the present invention, a hot-air circulating position and number of the gas extraction unit in each of the zones of the furnace (E _A) and area (E _B), the position and the number of hot air introduction portion provided in the hot air circulation type heating oven, a hot air circulation type Adjusting the scale (size) of the heating furnace, the heat retention of the apparatus, etc., the temperature of the mixed gas (T _mix ) that is obtained by mixing the gas extracted from each of the zone (E _A ) and zone (E _B ) It is preferable that the difference between (° C.) and the temperature (Ta) (° C.) of the hot air introduced into the hot air circulating heating furnace is 5 ° C. or less, further 4 ° C. or less, and particularly 3 ° C. or less.

Although not limited, as a hot air circulation system in a hot air circulation type heating furnace preferably employed in the method of the present invention, the one exemplified in FIG. 2 can be exemplified.
In FIG. 2, 1 is a hot-air circulating heating furnace, 2 is an inlet of the hot-air circulating heating furnace, 3 is an outlet of the hot-air circulating heating furnace, 4 is a continuous conveying means such as a conveyor, and 5 is an acrylic polymerizable composition or Acrylic resin cured product, 6a, 6b, 6c and 6d are hot air introduction parts in the hot air circulation heating furnace, 7a, 7b, 7c and 7d are gas (hot air) extraction parts in the hot air circulation heating furnace, and 8a and 8b are pumps Gas circulation devices such as 9a and 9b indicate heat exchangers.
In the apparatus shown in FIG. 2, two hot air introduction portions 6a and 6b and two 6c and 6d are provided in the upper and lower portions of the hot air circulating heating furnace, respectively, and in the upper and lower portions of the hot air circulating heating furnace. Two take-out portions 7a and 7b and 7c and 7d for gas (hot air) are provided. The extraction portion 7a and 7c of the inlet portion 6a and 6c and gas hot air is provided with the above-mentioned areas (E _A), extraction unit 7b and 7d of the inlet portion 6b and 6d and gas hot air above the area ( E _B ).
In the apparatus of FIG. 2, before the hot air introduced into the hot air circulation heating furnace from the hot air introduction parts 6a, 6b, 6c and 6d sufficiently heats the hot air circulation heating furnace, the gas extraction part 7a, It is necessary to consider the mutual arrangement position of the hot air introduction parts 6a, 6b, 6c and 6d and the gas extraction parts 7a, 7b, 7c and 7d so that they are not taken out from 7b, 7c and 7d. .

In the apparatus shown in FIG. 2, zones reduced gas [general hot air introduced into the hot air circulation type heating furnace temperature of the temperature taken from the take-out portion 7a of the gas is provided over the _{(E A) (Ta) (} ℃) The gas having a lower temperature than the gas is a gas having a high temperature taken out from the gas take-out section 7b provided in the upper part of the section (E _B ) [generally, the temperature (Ta) of hot air introduced into the hot air circulation heating furnace. After being mixed with (a gas having a temperature higher than (° C.)] to become a mixed gas, the hot air is sent to the heat exchanger 9a by the gas circulation device 8a and introduced into the hot air circulation heating furnace 1 by the heat exchanger 9a The temperature is adjusted to the temperature (Ta) (usually heating temperature control), and is again introduced (circulated) from the hot air introduction sections 6a and 6b into the hot air circulation type heating furnace.
Further, a gas with a lowered temperature taken out from the gas take-out part 7c provided at the lower part of the hot air circulating heating furnace [generally, the temperature is higher than the temperature (Ta) (° C.) of hot air introduced into the hot air circulating heating furnace. The lower gas] is a gas with a higher temperature taken out from the gas take-out section 7d provided at the lower part of the section (E _B ) [generally from the temperature (Ta) (° C.) of hot air introduced into the hot-air circulating furnace. Is mixed with the gas having a high temperature] to be a mixed gas, which is then sent to the heat exchanger 9b by the gas circulation device 8b and introduced into the hot air circulation heating furnace 1 by the heat exchanger 9b (Ta ) (Usually heating temperature control), and is again introduced (circulated) from the hot air introduction sections 6c and 6c to the hot air circulation type heating furnace.

When the apparatus shown in FIG. 2 is used, the acrylic resin cured product can be produced with extremely high thermal energy efficiency and high productivity by reusing and circulating the gas taken out from the hot-air circulating heating furnace.
In the apparatus shown in FIG. 2, two hot air introduction parts are provided at each of the upper and lower parts of the hot air circulation heating furnace, and two gas (hot air) extraction parts are provided at the upper and lower parts of the hot air circulation heating furnace, respectively. Although provided, the apparatus used in the present invention is not limited to the apparatus shown in FIG. 2, and the number of hot air introduction parts and gas (hot air) extraction parts may be larger than in FIG. 2.
Moreover, in the apparatus of FIG. 2, introduction of hot air from the upper part of the hot air circulation type heating furnace and removal of gas (hot air), introduction of hot air from the lower part of the hot air circulation type heating furnace and extraction of gas (hot air), However, the present invention is not limited to this. For example, hot air from the upper part of the hot-air circulating heating furnace is used, but the two gas-circulation devices 8a and 8b and the two heat exchangers 9a and 9b are used. And introduction of gas (hot air) and introduction of hot air from the lower part of the hot air circulation type heating furnace and removal of gas (hot air) using one gas circulation device and one heat exchanger It doesn't matter.
In addition, when the gas (usually air) in the hot air circulation heating furnace is contaminated by components generated from the acrylic polymerizable composition, the hot air circulating outside the hot air circulation heating furnace is made clean. You may employ | adopt the system which can take in new gas (air) to a hot-air circulation path.

In carrying out the method of the present invention, an acrylic polymerizable composition is supplied to a molding space that continuously moves in a hot air circulation type heating furnace, and is polymerized and cured while moving in the hot air circulation type heating furnace, and then an acrylic resin. Any method or apparatus can be used as long as it is a cured product and the acrylic resin cured product can be continuously taken out from the hot-air circulating heating furnace, and is not particularly limited. In the continuous production technology of the acrylic resin cured product Conventionally employed methods and devices can be employed.
For example, (1) a long film is sequentially supplied and placed on one endless belt that continuously advances in a hot-air circulating heating furnace, and retainers are arranged on both sides so that the upper groove is opened in a concave groove shape. A method of forming a continuous molding space, injecting an acrylic polymerizable composition into the molding space, and polymerizing and curing it while moving forward in the hot air circulating heating furnace, (2) continuously in the hot air circulating heating furnace A retainer (weir) is arranged on both sides between two endless belts arranged at a predetermined interval above and below to form a continuous enclosed molding space having a square cross section, and in the molding space A method in which an acrylic polymerizable composition is injected and polymerized and cured while moving forward in a hot-air circulating heating furnace. (3) In the method (2), a molding formed by two endless belts and a side retainer. (4) A plurality of dies having a predetermined finite molding space (cavity) are placed on an endless belt that continuously moves forward in a hot-air circulating heating furnace. Examples thereof include a method in which the resin is continuously moved forward, filled with an acrylic polymerizable composition in each mold, and polymerized and cured while being moved forward in a hot air circulation type heating furnace.
The acrylic resin cured product taken out from the hot air circulation type heating furnace is cooled to room temperature, and the long acrylic resin cured product is cut into an appropriate size as required according to the application, etc. The scale acrylic resin cured product can be stored, distributed, sold, and secondary-processed in the same size.

  The “unsaturated monomer mainly composed of methyl methacrylate” contained in the acrylic polymerizable composition used in the present invention means the total mass (total mass) of unsaturated monomers contained in the acrylic polymerizable composition. ) Based on unsaturated monomers containing 50% by weight or more of methyl methacrylate. The acrylic polymerizable composition used in the present invention may contain methyl methacrylate in a proportion of 60% by mass or more based on the total mass of unsaturated monomers contained in the acrylic polymerizable composition. Preferably, it is contained in a proportion of 70% by mass or more. Based on the total mass of unsaturated monomers contained in the acrylic polymerizable composition, the acrylic resin cures with excellent weather resistance and high-class feeling by containing methyl methacrylate in the above-mentioned proportion. You can get things.

  The acrylic polymerizable composition used in the present invention contains 50% by mass or less of other unsaturated monomers together with methyl methacrylate based on the total mass of unsaturated monomers contained in the acrylic polymerizable composition. The content of the other unsaturated monomer is preferably 40% by mass or less, and preferably 70% by mass or less based on the total mass of the unsaturated monomer. More preferred.

  The type of the other unsaturated monomer is not particularly limited and may be any unsaturated monomer that can be copolymerized with methyl methacrylate. As a specific example, the number of carbon atoms in one molecule is 1-18. Monohydric alcohol or ester of monohydric phenol and acrylic acid, ester of monohydric alcohol or monohydric phenol and methacrylic acid having 2 to 18 carbon atoms in one molecule, carbon atom number of 2 in one molecule Monoester of dihydric alcohol of ~ 4 with acrylic acid or methacrylic acid, acrylic acid, methacrylic acid, acrylonitrile, acrylamide, styrene, α-methylstyrene, vinyl acetate, vinyl chloride, vinylidene chloride, vinylidene fluoride, ethylene, anhydrous Monofunctional unsaturation such as maleic acid, maleic acid, fumaric acid, butadiene, isoprene, glycidyl (meth) acrylate (Meth) acrylic acid and ethylene glycol, polyethylene glycol, propylene glycol, 1,3-butanediol, neopentyl glycol, 1,6-hexanediol, tetramethylolmethane, dimethylolethane, trimethylolethane, dimethylol Polyfunctional unsaturated monomers such as polyvalent esters with polyhydric alcohols such as propane, trimethylolpropane, pentaerythritol and dipentaerythritol, allyl (meth) acrylate, divinylbenzene and triallyl isocyanurate; 1 type, or 2 or more types of these can be used.

  In particular, it is desirable to use a small amount of a polyfunctional unsaturated monomer together with methyl methacrylate from the viewpoint of improving the heat resistance and stain resistance of the cured acrylic resin obtained by polymerization and curing. As the types of polyfunctional unsaturated monomers, those described above can be used, and in particular, ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, and the like. preferable. The content of the polyfunctional unsaturated monomer in the acrylic polymerizable composition is preferably 0.05 to 5% by mass based on the total mass of the unsaturated monomer contained in the acrylic polymerizable composition. 0.1 to 4% by mass is more preferable. When the content of the polyfunctional unsaturated monomer is less than the above range, the acrylic resin cured product obtained by polymerization and curing may be insufficient in heat resistance, stain resistance, etc. If the amount is too large, the cured acrylic resin obtained by polymerization and curing tends to be too hard, the bending resistance during processing increases, and the bending workability tends to deteriorate.

The acrylic polymerizable composition used in the present invention contains only an unsaturated monomer mainly composed of methyl methacrylate as an organic polymerizable component (organic polymer component), and contains an already polymerized organic polymer. Or an acrylic monomer mainly composed of a structural unit derived from methyl methacrylate for adjusting the viscosity of the acrylic polymerizable composition together with an unsaturated monomer mainly composed of methyl methacrylate. The coalescence may be dissolved and contained as necessary.
When the acrylic polymerizable composition contains an acrylic polymer, it may contain only one kind of acrylic polymer, or two or more kinds of acrylic polymers having different compositions and molecular weight distributions. It may contain.
An acrylic polymerizable composition containing an acrylic polymer together with an unsaturated monomer mainly composed of methyl methacrylate is, for example, an acrylic polymer composed mainly of methyl methacrylate. Examples thereof include a method of directly dissolving in a saturated monomer and a method of previously polymerizing an unsaturated monomer mainly composed of methyl methacrylate to a low polymerization rate.

In the case where the acrylic polymerizable composition contains an acrylic polymer together with an unsaturated monomer mainly composed of methyl methacrylate, the content of the acrylic polymer is a monomer mainly composed of methyl methacrylate. And based on the total mass of the acrylic polymer, 5 to 40% by mass is preferable, and 15 to 30% by mass is more preferable.
By including the acrylic polymer in an amount within the above-mentioned range in the acrylic polymerizable composition, the viscosity of the acrylic polymerizable composition can be adjusted to a viscosity suitable for production of a plate-like body. . When the content of the acrylic polymer in the acrylic polymerizable composition is larger than the above range, poor appearance of the cured acrylic resin obtained by polymerization and curing, deterioration of physical properties, and the like are likely to occur.

The acrylic polymerizable composition used in the present invention may or may not contain an inorganic powder. When the inorganic powder is contained, the heat resistance and hardness of the cured acrylic resin obtained by polymerization and curing are increased. Furthermore, a marble-like cured acrylic resin (acrylic resin artificial marble) can be produced by polymerizing and curing an acrylic polymerizable composition containing an inorganic powder. On the other hand, when the acrylic polymerizable composition does not contain an inorganic powder, a transparent acrylic resin cured product is generally obtained.
The continuous production method of the present invention is particularly suitable as a continuous production technique for an acrylic resin artificial marble using an acrylic polymerizable composition containing an inorganic powder.

  When the acrylic polymerizable composition contains an inorganic powder, any inorganic powder that is insoluble in an unsaturated monomer mainly composed of methyl methacrylate and does not inhibit the polymerization and curing can be used. Specific examples include aluminum hydroxide, aluminum oxide, calcium carbonate, calcium silicate, calcium aluminate, barium sulfate, calcium sulfate, magnesium hydroxide, silica, talc, clay, and the like. Or 2 or more types can be used. Among the above, aluminum hydroxide, magnesium hydroxide, barium sulfate, and silica are preferably used, and aluminum hydroxide is more preferably used from the viewpoint of obtaining a high-quality acrylic resin cured product.

  When the acrylic polymerizable composition contains an inorganic powder, its content may vary depending on the performance, appearance, color tone, etc. required for the acrylic resin cured product. Based on the total mass of the unsaturated monomer and the inorganic powder as a main component, 80 to 20% by mass is preferable, and 70 to 40% by mass is more preferable. A cured acrylic resin obtained from an acrylic polymerizable composition that does not contain inorganic powder or has an inorganic powder content less than the above range is more resistant to heat than those containing an inorganic powder in the above range. , There is a tendency for the hardness and the like to be low, and it does not show marble-like. On the other hand, if the content of the inorganic powder in the acrylic polymerizable composition is more than the above range, the acrylic resin polymerization raw material mixture cannot be slurried and becomes difficult to mix, and the strength of the resulting cured acrylic resin, etc. Decreases.

In order to obtain an acrylic resin cured product having a pattern such as marble or granite having a greater decorative effect, the acrylic polymerizable composition used in the present invention, together with the above-described inorganic powder, has a predetermined particle size or Granules and crushed particles having a color tone can be contained.
In addition, the acrylic polymerizable composition used in the present invention includes a coupling agent such as phosphate ester or silane, a release agent such as stearic acid, a dye / pigment, a reinforcing material, a modifier, and a stabilizer as necessary. 1 type, or 2 or more types of various additives, such as an agent, a ultraviolet absorber, a flame retardant, a polymerization regulator, an antibacterial agent, and an impact modifier.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples and the like, but the present invention is not limited to the following examples. In the following Examples and Comparative Examples, the reaction rate of the acrylic polymerizable composition, the measurement of the product temperature of the acrylic polymerizable composition and the cured acrylic resin, and the time (A) described above [acrylic The temperature of the hot air introduced into the hot-air circulating heating furnace from the time when the polymerizable composition reaches the inlet of the hot-air circulating heating furnace (Ta) (° C) The time required to reach the same temperature as above] and the time of (B) above [the temperature of the hot air introduced into the hot air circulating heating furnace (Ta) when the product temperature of the acrylic polymerizable composition or acrylic resin cured product is The measurement of the time required to reach the outlet of the hot-air circulating heating furnace from the time when the temperature reached the same temperature as (° C.) was determined as follows.

(1) Reaction rate of acrylic polymerizable composition:
A part (Wa) of the cured acrylic resin is sampled and dissolved in dichloromethane, and the dichloromethane solution is analyzed by gas chromatography (“GC-14A” manufactured by Shimadzu Corporation). The amount of the monomer was measured, and the reaction rate of the acrylic polymerizable composition was determined by the following mathematical formula.

Reaction rate (%) of acrylic polymerizable composition = [1− {Wc ÷ (Wa × Wb)}] × 100

[Wa is the mass (g) of the sample collected, Wb is the content of all monomers in the acrylic polymerizable composition, and Wc is the mass of the unreacted monomer contained in the sample ( g). ]

(2) Product temperature of acrylic polymerizable composition and acrylic resin cured product:
At the center of the acrylic polymerizable composition cast on the conveyor belt (concave groove-shaped forming space) (the intersection of two diagonal lines in the rectangular cross section of the cast perpendicular to the direction of travel of the conveyor belt), Yokogawa Acrylic polymerizable composition that moves through the hot air circulating heating furnace through the entire moving path from the inlet to the outlet of the hot air circulating heating furnace by inserting a thermocouple connected to a hybrid recorder manufactured by Denki Co., Ltd. and its polymerization The temperature of the cured product (acrylic resin cured product) was measured over time.

(3) Time of (A) and time of (B):
The product temperatures of the acrylic polymerizable composition and the cured acrylic resin measured over time in (2) above were drawn on a graph, and the time (A) and the time (B) were determined from the graph. At that time, the time when the cured acrylic resin reached the outlet of the hot-air circulating heating furnace is the length (m) of the hot-air circulating heating furnace of the acrylic polymerizable composition or the cured acrylic resin. It was obtained by dividing by the moving speed (m / min) in the hot air circulation type heating furnace.

Example 1
(1) A cured acrylic resin was produced using the apparatus shown in FIG. 2 (distance from the inlet 2 to the outlet 3 in the hot-air circulating heating furnace 1 = 10 m). In addition, as an apparatus for continuously producing an acrylic resin cured product, a mold release film is placed on the conveyor 4, weirs are arranged on both sides, and an open groove-shaped molding space (inner dimension of the groove; What formed width x height = 100 cm x 2 cm was used.
(2) 285 parts by mass of methyl methacrylate (MMA), 100 parts by mass of methacrylic resin (PMMA, “Parabeads” manufactured by Kuraray Co., Ltd.), 15 parts by mass of 1,3-butylene glycol dimethacrylate (BG), aluminum hydroxide powder ( 600 parts by weight of “Hijilite” manufactured by Showa Denko KK were mixed and degassed under vacuum to prepare a mixture.

(3) After adjusting the temperature of the mixture obtained in (2) above to 30 ° C., it is continuously fed into the in-line mixer at a feed rate of 5.5 kg / min with a metering pump, and at the same time tertiary butyl peroxyneo Decanoate (thermal polymerization initiator, “Perbutyl ND” manufactured by Nippon Oil & Fats Co., Ltd., 10 hour half-life temperature = 46.4 ° C.) is charged at a rate of 8 g per 1 kg of the mixture and mixed to obtain a highly viscous liquid acrylic system A polymerizable composition is prepared, and the acrylic polymerizable composition is supplied to the molding space of the continuous production apparatus at a position immediately before the inlet 2 of the hot-air circulating heating furnace so that the liquid thickness becomes 11 mm. Then, it was cast into a plate shape and continuously moved in the hot-air circulating heating furnace 1 under the condition of a moving speed of the conveyor 4 of 0.33 m / min to polymerize and cure to produce an acrylic resin cured product. The product temperature of the acrylic polymerizable composition was raised to 32 ° C. immediately before entering the hot-air circulating heating furnace 1.
In performing the manufacturing operation of this acrylic resin cured product, hot air having a temperature of 80 ° C. is introduced into the hot air circulation heating furnace 1 from the hot air introduction parts 6a, 6b, 6c and 6d in advance and the gas (hot air) is taken out. The gas in the hot air circulation heating furnace 1 is taken out from the parts 7a, 7b, 7c and 7d in the same amount as the amount of hot air introduced, and hot air is circulated in the hot air circulation heating furnace 1, Was previously adjusted to 78 ° C. ± 2 ° C., and the acrylic polymerizable composition was supplied from the inlet 2 into the hot-air circulating heating furnace 1 thus adjusted in temperature, and the hot-air circulating heating furnace 1 The inside was moved to the outlet 3 at a moving speed of 0.33 m / min to perform polymerization curing.

(4) In the continuous production operation of the cured acrylic resin of Example 1, as shown in Table 1 below, the acrylic polymerizable composition is gradually heated in the hot air circulation heating furnace 1. The temperature rose and reached 80 ° C. after 17 minutes, reached 141 ° C. (peak temperature) after 19 minutes, and then gradually decreased. After 30 minutes, it was taken out from the hot air circulating heating furnace at 103 ° C.
As a result, the ratio (A) / (B) of time (A) to time (B) was 1.3. Moreover, the reaction rate of the obtained acrylic resin cured product was 99.7%, and was sufficiently cured by polymerization. Furthermore, no bubbles were generated and the appearance was good.
(5) Further, during continuous production of the cured acrylic resin, a mixed gas (gas circulation device 8a and gas mixture mixed after taking out from the gas (hot air) take-out portions 7a, 7b, 7c and 7d of the hot-air circulating heating furnace 1 is used. As a result of measuring the temperature of the mixed gas before being sent to the heat exchangers 9a and 9b by 8b, the average temperature is 78.4 ° C., which is very close to the temperature of the hot air introduced into the hot air circulating heating furnace 1 80 ° C. It was a thing. As a result, the amount of heat energy used when the mixed gas is heated and adjusted to 80 ° C. with the heat exchangers 9a and 9b and recirculated to the hot-air circulating heating furnace is extremely small, and the heat energy efficiency is excellent. It was.

Example 2
(1) A mixture was prepared by adopting the same composition and operation as in (2) of Example 1, the temperature was adjusted to 30 ° C., and then continuously fed to an in-line mixer at 5.5 kg / min with a metering pump. At the same time, bis (4-tertiarybutylcyclohexyl) peroxydicarbonate (thermal polymerization initiator, “Perkadox 16” manufactured by Kayaku Akzo Co., Ltd., 10 hour half-life temperature = 44 ° C.) at a rate of 6 g per 1 kg of the mixture Into the molding space of the same continuous production apparatus used in Example 1 to prepare an acrylic polymerizable composition by charging and mixing, the acrylic polymerizable composition was used in Example 1 with a liquid thickness of 11 mm, It is supplied at a position immediately before the inlet 2 of the hot air circulation heating furnace and cast into a plate shape, and is continuously moved in the hot air circulation heating furnace 1 under the condition that the conveyor 4 moves at a speed of 0.33 m / min. Hardened A ril-based resin cured product was produced. The product temperature of the acrylic polymerizable composition was raised to 34 ° C. immediately before entering the hot-air circulating heating furnace 1.
In performing the manufacturing operation of this acrylic resin cured product, hot air having a temperature of 70 ° C. is introduced into the hot air circulation heating furnace 1 from the hot air introduction parts 6a, 6b, 6c and 6d in advance and the gas (hot air) is taken out. The gas in the hot air circulation heating furnace 1 is taken out from the parts 7a, 7b, 7c and 7d in the same amount as the amount of hot air introduced, and hot air is circulated in the hot air circulation heating furnace 1, Is adjusted in advance to 68 ° C. ± 2 ° C., and the acrylic polymerizable composition is supplied from the inlet 2 into the hot-air circulating heating furnace 1 adjusted in temperature as described above, and the hot-air circulating heating furnace 1 The inside was moved to the outlet 3 at a moving speed of 0.33 m / min to perform polymerization curing.

(2) In the continuous production of the cured acrylic resin of the above (1), as shown in Table 1 below, the acrylic polymerizable composition is heated in the hot air circulation heating furnace 1 and gradually heated. The temperature rose to 70 ° C. after 20 minutes, reached 147 ° C. (peak temperature) after 22 minutes, then gradually decreased, and was taken out from the hot air circulating heating furnace at 110 ° C. after 30 minutes.
As a result, the ratio (A) / (B) of time (A) to time (B) was 2.0. Further, the reaction rate of the obtained cured acrylic resin was 99.6%, and was sufficiently polymerized and cured, and no bubbles were generated, and the appearance was good.
(3) Also, during the continuous production of the cured acrylic resin, the mixed gas (the gas circulation device 8a and the mixed gas) taken out from the gas take-out portions 7a, 7b, 7c and 7d of the hot air circulation heating furnace 1 (hot air) As a result of measuring the temperature of the mixed gas before being sent to the heat exchangers 9a and 9b by 8b, the average temperature is 69.2 ° C., which is very close to the temperature of hot air 70 ° C. introduced into the hot air circulating heating furnace 1 The amount of heat energy used for heating and adjusting the mixed gas to 70 ° C. in the heat exchangers 9a and 9b and recirculating it to the hot-air circulation type heating furnace is very small, and the heat energy efficiency is extremely excellent. .

Example 3
(1) A mixture was prepared by employing the same formulation and operation as in (2) of Example 1, and 1 part by weight of black pigment (“Sopro Toner BK” manufactured by Sanyo Chemical Co., Ltd.) was added to 100 parts by weight of the mixture. A black mixture was prepared by adding in proportions.
(2) Using the black mixture prepared in (1) above, the same operation as in (1) of Example 1 was employed to prepare a black acrylic polymerizable composition and continuously produce a cured acrylic resin. Went. In Example 3, the product temperature of the acrylic polymerizable composition was raised to 31 ° C. immediately before entering the hot-air circulating heating furnace 1.

(3) In the continuous production of the cured acrylic resin of the above (2), as shown in Table 1 below, the acrylic polymerizable composition is heated in the hot air circulation heating furnace 1 and gradually heated. The temperature rose to 80 ° C. after 18 minutes, reached 140 ° C. (peak temperature) after 20 minutes, gradually decreased in temperature, and was taken out from the hot air circulating heating furnace at 101 ° C. after 32 minutes.
As a result, the ratio (A) / (B) of time (A) to time (B) was 1.3. Further, the reaction rate of the obtained cured acrylic resin was 99.6%, and was sufficiently polymerized and cured, and no bubbles were generated, and the appearance was good.
(4) Further, during continuous production of the cured acrylic resin, a mixed gas (gas circulation device 8a and gas mixture mixed after taking out from the gas (hot air) take-out portions 7a, 7b, 7c and 7d of the hot air circulating heating furnace 1 is used. As a result of measuring the temperature of the mixed gas before being sent to the heat exchangers 9a and 9b by 8b, the average temperature is 77.9 ° C., which is close to the temperature of 80 ° C. of the hot air introduced into the hot-air circulating heating furnace 1, A small amount of heat energy was used when the mixed gas was heated to 80 ° C. with the heat exchangers 9a and 9b and recirculated to the hot-air circulating heating furnace, and the heat energy efficiency was excellent.

Example 4
(1) A mixture was prepared by employing the same composition and operation as in (2) of Example 1, and white pigment (“AT K-39 (B)” manufactured by Dainichi Seika Co., Ltd.) 1 was added to 100 parts by mass of the mixture. A white mixture was prepared by mixing parts by mass, and the white acrylic resin cured product was continuously produced using the white mixture by performing the same operation as (3) of Example 1. The white acrylic resin cured product was pulverized with a roll mill, and the pulverized product was sieved to produce white crushed particles having a particle size of 0.1 to 2.4 mm.
(2) The black acrylic resin cured product obtained in (2) of Example 3 was pulverized with a roll mill, and the pulverized product was sieved to produce black crushed particles having a particle size of 0.1 to 2.4 mm. .
(3) The same formulation and operation as in (2) of Example 1 were adopted to prepare a mixture, and with respect to 100 parts by mass of the mixture, 2 parts by mass of the white crushed particles obtained in (1) above and the above The black crushed particles obtained in (2) were added at a rate of 8 parts by mass to prepare a mixture containing white crushed particles and black crushed particles.
(4) Using the mixture containing white crushed particles and black crushed particles prepared in (3) above, the same operation as in (1) of Example 1 was employed to prepare an acrylic polymerizable composition and acrylic Continuous production of a cured resin was carried out. In Example 4, the product temperature of the acrylic polymerizable composition was raised to 31 ° C. immediately before entering the hot air circulating heating furnace 1.

(5) In the continuous production of the cured acrylic resin of the above (4), as shown in Table 1 below, the acrylic polymerizable composition is heated in the hot air circulating heating furnace 1 and gradually heated. The temperature rose to 80 ° C. after 15 minutes, reached 148 ° C. (peak temperature) after 17 minutes, then gradually decreased, and after 29 minutes, it was taken out from the hot-air circulating heating furnace at 105 ° C.
As a result, the ratio (A) / (B) of time (A) to time (B) was 1.1. Moreover, the reaction rate of the obtained acrylic resin cured product was 99.7%, and was sufficiently cured by polymerization. Furthermore, no bubbles were generated and the appearance was good.
(6) Also, during continuous production of the acrylic resin cured product, a mixed gas (gas circulation device 8a and gas mixture) mixed after being taken out from the gas take-out portions 7a, 7b, 7c and 7d of the hot-air circulating heating furnace 1 (hot air) As a result of measuring the temperature of the mixed gas before being sent to the heat exchangers 9a and 9b by 8b, the average temperature is 78.8 ° C., which is very close to the temperature of hot air 80 ° C. introduced into the hot air circulating heating furnace 1 The amount of heat energy required for heating and adjusting the temperature of the mixed gas to 80 ° C. in the heat exchangers 9a and 9b and recirculating it to the hot-air circulating heating furnace was small, and the heat energy efficiency was excellent.

<< Comparative Example 1 >>
(1) A mixture was prepared by adopting the same composition and operation as in (2) of Example 1, the temperature was adjusted to 30 ° C., and then continuously fed to an in-line mixer at 2.9 kg / min with a metering pump. At the same time, lauroyl peroxide (thermal polymerization initiator, “Perroyl L” manufactured by Nippon Oil & Fats Co., Ltd., 10 hour half-life temperature = 61.6 ° C.) was added at a rate of 8 g per 1 kg of the mixture and mixed to produce acrylic polymerization. In the molding space of the same continuous production apparatus used in Example 1 so that the liquid thickness is 11 mm, the acrylic polymerizable composition is placed in the inlet 2 of the hot-air circulating heating furnace. It is supplied at the immediately preceding position and cast into a plate shape, and is continuously moved in the hot air circulating heating furnace 1 under the condition of a moving speed of the conveyor 4 of 0.18 m / min to polymerize and cure the acrylic resin cured product. Manufactured. The product temperature of the acrylic polymerizable composition was raised to 31 ° C. immediately before entering the hot-air circulating heating furnace 1.
In performing the manufacturing operation of this acrylic resin cured product, hot air having a temperature of 70 ° C. is introduced into the hot air circulation heating furnace 1 from the hot air introduction parts 6a, 6b, 6c and 6d in advance and the gas (hot air) is taken out. The gas in the hot air circulation heating furnace 1 is taken out from the parts 7a, 7b, 7c and 7d in the same amount as the amount of hot air introduced, and hot air is circulated in the hot air circulation heating furnace 1, Is adjusted in advance to 68 ° C. ± 2 ° C., and the acrylic polymerizable composition is supplied from the inlet 2 into the hot-air circulating heating furnace 1 adjusted in temperature as described above, and the hot-air circulating heating furnace 1 The inside was moved to the outlet 3 at a moving speed of 0.18 m / min to carry out polymerization curing.

(2) In the continuous production of the cured acrylic resin of the above (1), as shown in Table 1 below, the acrylic polymerizable composition is heated in the hot air circulation heating furnace 1 and gradually heated. The temperature rose to 70 ° C. after 43 minutes, reached 122 ° C. (peak temperature) after 48 minutes, gradually decreased in temperature, and was taken out from the hot air circulation heating furnace at 91 ° C. after 56 minutes.
As a result, the ratio (A) / (B) of time (A) to time (B) was 3.3. Moreover, the reaction rate of the obtained acrylic resin hardened | cured material was 92.9%, and the reaction rate was low compared with Examples 1-4.
(3) Also, during the continuous production of the cured acrylic resin, the mixed gas (the gas circulation device 8a and the mixed gas) taken out from the gas take-out portions 7a, 7b, 7c and 7d of the hot air circulation heating furnace 1 (hot air) As a result of measuring the temperature of the mixed gas before being sent to the heat exchangers 9a and 9b by 8b, the average temperature is 61.8 ° C., so that the temperature of the hot air introduced into the hot air circulating heating furnace 1 is 70 ° C. However, the amount of heat energy used was much larger than those of Examples 1 to 4, and the heat energy efficiency was inferior to Examples 1 to 4.

<< Comparative Example 2 >>
(1) A mixture was prepared by adopting the same composition and operation as in (2) of Example 1, the temperature was adjusted to 30 ° C., and then continuously fed into an in-line mixer at 1.6 kg / min with a metering pump. At the same time, lauroyl peroxide (thermal polymerization initiator, “Perroyl L” manufactured by Nippon Oil & Fats Co., Ltd., 10 hour half-life temperature = 61.6 ° C.) was added at a rate of 8 g per 1 kg of the mixture and mixed to produce acrylic polymerization. In the molding space of the same continuous production apparatus used in Example 1 so that the liquid thickness is 11 mm, the acrylic polymerizable composition is placed in the inlet 2 of the hot-air circulating heating furnace. It is supplied at the immediately preceding position and cast into a plate shape, and continuously moves in the hot-air circulating heating furnace 1 under the condition of a moving speed of the conveyor 4 of 0.10 m / min to polymerize and cure the acrylic resin cured product. Manufactured. The product temperature of the acrylic polymerizable composition was raised to 33 ° C. immediately before entering the hot-air circulating heating furnace 1.
In performing the manufacturing operation of this acrylic resin cured product, hot air having a temperature of 70 ° C. is introduced into the hot air circulation heating furnace 1 from the hot air introduction parts 6a, 6b, 6c and 6d in advance and the gas (hot air) is taken out. The gas in the hot air circulation heating furnace 1 is taken out from the parts 7a, 7b, 7c and 7d in the same amount as the amount of hot air introduced, and hot air is circulated in the hot air circulation heating furnace 1, Is adjusted in advance to 68 ° C. ± 2 ° C., and the acrylic polymerizable composition is supplied from the inlet 2 into the hot-air circulating heating furnace 1 adjusted in temperature as described above, and the hot-air circulating heating furnace 1 The inside was moved to the outlet 3 at a moving speed of 0.10 m / min to perform polymerization curing.

(2) In the continuous production of the cured acrylic resin of the above (1), as shown in Table 1 below, the acrylic polymerizable composition is heated in the hot air circulation heating furnace 1 and gradually heated. The temperature rose to 70 ° C. after 45 minutes, reached 120 ° C. (peak temperature) after 50 minutes, gradually decreased in temperature, and taken out from the hot air circulating heating furnace at 72 ° C. after 105 minutes.
As a result, the ratio (A) / (B) of time (A) to time (B) was 0.8. Moreover, the reaction rate of the obtained acrylic resin hardened | cured material was 93.3%, and the reaction rate was low compared with Examples 1-4.
(3) Also, during the continuous production of the cured acrylic resin, the mixed gas (the gas circulation device 8a and the mixed gas) taken out from the gas take-out portions 7a, 7b, 7c and 7d of the hot air circulation heating furnace 1 (hot air) As a result of measuring the temperature of the mixed gas before being sent to the heat exchangers 9a and 9b by 8b, the average temperature is 62.5 ° C., so that the temperature of the hot air introduced into the hot air circulating heating furnace 1 is 70 ° C. The amount of heat energy used was much larger than those of Examples 1 to 4, and the heat energy efficiency was inferior to Examples 1 to 4.

<< Comparative Example 3 >>
(1) A mixture was prepared by adopting the same composition and operation as in (2) of Example 1, the temperature was adjusted to 30 ° C., and then continuously fed to an in-line mixer at 5.7 kg / min with a metering pump. At the same time, diisobutyryl peroxide (thermal polymerization initiator, “Perroyl IB” manufactured by NOF Corporation, 10-hour half-life temperature = 32.7 ° C.) was added at a rate of 8 g per 1 kg of the mixture and mixed. A polymerizable composition was prepared, and the acrylic polymerizable composition was introduced into the molding space of the same continuous production apparatus used in Example 1 so that the liquid thickness was 11 mm. Is supplied at a position just before the plate and cast into a plate shape, and is continuously moved in the hot-air circulating heating furnace 1 under the condition of a moving speed of the conveyor 4 of 0.34 m / min. Tried to manufacture However, the temperature of the acrylic polymerizable composition rises to 48 ° C. just before entering the hot-air circulating heating furnace 1, then thickens and becomes impossible to cast, and continuously produces a cured acrylic resin. I couldn't.

  In the case of the present invention, the acrylic resin cured product is sufficiently polymerized and cured using a hot air circulation type heating furnace with a simple structure without requiring complicated temperature control and temperature control, and has excellent physical properties and appearance. Since the cured acrylic resin can be easily produced with good productivity, the present invention is extremely useful as a continuous production method for various cured acrylic resins including acrylic resin artificial marble.

It is a figure which shows the log | history of the product temperature of the acrylic polymerizable composition and acrylic resin hardened | cured material in a hot-air circulation type heating furnace. It is a figure which shows an example of the continuous manufacturing apparatus (hot air circulation type heating furnace) of the acrylic resin hardened | cured material which can be preferably used by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hot-air circulation heating furnace 2 Hot-air circulation heating furnace inlet 3 Hot-air circulation heating furnace outlet 4 Continuous conveyance means, such as a conveyor 5 Acrylic polymerizable composition or acrylic resin cured product 6a Hot-air introduction part 6b Hot-air introduction part 6c Hot air introduction part 6d Hot air introduction part 7a Gas (hot air) extraction part 7b Gas (hot air) extraction part 7c Gas (hot air) extraction part 8d Gas (hot air) extraction part 8a Gas circulation device 8b such as a pump, gas circulation such as a pump Device 9a Heat exchanger 9b Heat exchanger

Claims (7)

An acrylic polymerizable composition containing an unsaturated monomer mainly composed of methyl methacrylate and a thermal polymerization initiator is supplied to a molding space that continuously moves forward in a hot-air circulating heating furnace and polymerized and cured. A method for continuously producing a cured acrylic resin,
As the thermal polymerization initiator, a thermal polymerization initiator having a 10-hour half-life temperature that is 10 to 60 ° C. lower than the temperature (Ta) (° C.) of hot air introduced into the hot-air circulating heating furnace ; and
Hot air temperature (Ta) (° C.) at which the temperature of the acrylic polymerizable composition or its polymerized cured product is introduced into the hot-air circulating heating furnace from the time when the acrylic polymerizable composition reaches the inlet of the hot-air circulating heating furnace ) Is the same temperature as the temperature (Ta) (° C.) of hot air introduced into the hot air circulation heating furnace, where the temperature until reaching the same temperature as in (A) is (A). When the time from when the polymerization hardened material reaches the outlet of the hot air circulation heating furnace to (B) is taken as (A) / (B) = 1-3, the hot air circulation type Polymerizing and curing the acrylic polymerizable composition in a heating furnace;
A method for continuously producing a cured acrylic resin, characterized in that:   The continuous production method according to claim 1, wherein the temperature (Ta) (° C) of the hot air introduced into the hot air circulation heating furnace is a constant temperature within a range of 30 to 120 ° C.   The atmospheric temperature (Tb) (° C.) in the hot air circulating heating furnace is changed to [temperature of hot air introduced into the hot air circulating heating furnace (Ta) (° C.) − 10 (° C.)] and [hot air circulating heating furnace The continuous production method according to claim 1 or 2, wherein the temperature is maintained within a range of the temperature of hot air to be introduced (Ta) (° C) + 10 (° C)]. The area between the inlet of the hot-air circulating furnace and the temperature of the acrylic polymerizable composition or its polymerized cured product reaches the same temperature as the temperature (Ta) (° C) of the hot air introduced into the hot-air circulating furnace (E _A ) is provided with a gas outlet from the hot air circulation heating furnace, and the temperature of the hot air introduced into the hot air circulation heating furnace (Ta) (° C.) ) Is provided in the area (E _B ) between the point where the same temperature is reached and the outlet of the hot-air circulating heating furnace to the outlet of the hot-air circulating heating furnace, and the area (E _A ) and the area (E _B ) The gas extracted from the gas extraction unit provided in each is mixed to make a mixed gas, and the mixed gas is adjusted to the temperature (Ta) (° C.) of hot air introduced into the hot-air circulating heating furnace, and the hot-air circulating heating furnace The description in any one of claims 1 to 3 introduced into The continuous manufacturing method. The temperature (T _mix ) (° C) of the mixed gas obtained by mixing the gas extracted from the gas extraction section provided in each of the section (E _A ) and the section (E _B ), and hot air introduced into the hot-air circulating heating furnace The continuous production method according to claim 4 , wherein the difference from the temperature (Ta) (° C.) is 5 ° C. or less. The continuous production method according to any one of claims 1 to 5 , wherein the acrylic polymerizable composition is an acrylic polymerizable composition for producing an acrylic resin-based artificial marble further containing an inorganic powder. The continuous manufacturing method of any one of Claims 1-6 which manufactures plate-shaped acrylic resin hardened | cured material.

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