JP5084119B2 - Method for producing acrylic acid (salt) water-soluble polymer - Google Patents

Description

The present invention relates to a method for producing an acrylic acid (salt) -based water-soluble polymer. More specifically, the present invention relates to a method for producing an acrylic acid (salt) -based water-soluble polymer which exhibits an excellent function as a thickener and a flocculant and can be used in various fields such as raw materials for various industrial products.

Acrylic acid (salt) water-soluble polymer has excellent basic performance as a thickener, adhesive, flocculant, hygroscopic agent, desiccant, etc., added for excavating soil treatment agent, poultice and poultice In addition to chemicals, dredging agents, etc., it is widely used in medicine, paints, papermaking, detergents and cosmetics, water treatment, textile treatment, civil engineering and construction, agriculture and horticulture, adhesives, ceramics, manufacturing processes, and other fields. Yes. In addition, those of higher quality in terms of viscosity, amount of remaining monomer, etc. are used for foods and feeds, for example, as thickeners, noodle loosening promoters and pig gastric ulcer inhibitors. .

As a method for producing an acrylic acid (salt) -based water-soluble polymer, for example, a production method for obtaining a polymer by developing a monomer on a steel substrate such as a belt polymerizer and polymerizing it is preferably used. In such a production method, when the acrylic acid (salt) -based water-soluble polymer is a highly tacky polymer, the base steel and the polymer strongly adhere to each other and cannot be easily separated (separated). Do not mold). Various methods have been reported as a method for enhancing the releasability. For example, a method of making a belt of a belt polymerization machine a specific structure or material, an acrylic acid (salt) system by adding a surfactant A method for producing a water-soluble polymer, a method for supplying a release film on a belt substrate and winding it after polymerization, a method for attaching a release material on the belt substrate, and the like are known.

In the method of using a belt of a belt polymerization machine with a specific structure or material, for example, one using an electropolishing substrate or one having a curved structure in which the substrate of the belt is all made of resin ( For example, see Patent Document 1.) However, when an electropolishing substrate is used, the acrylic acid (salt) -based water-soluble polymer having strong adhesiveness may have insufficient releasability (effect). In addition, when using a resin base material, it is necessary to use a thick base material in order to obtain sufficient strength, and since it is a resin material, heat transfer is poor and heat removal is hardly expected. However, when polymerized without sufficient heat removal, only a polymer having a small molecular weight can be obtained. For example, sufficient performance may not be exhibited even when used as a thickener, flocculant, cataplasm, etc. .

On the other hand, in the method of producing an acrylic acid (salt) -based water-soluble polymer by adding a surfactant, the product purity and product safety may be reduced. Further, as a method for supplying and winding a release film, a method of placing a synthetic resin film on a base material is disclosed (for example, see Patent Document 2). According to this method, it is described that the film is wound up at the belt exit, but since the apparatus becomes complicated and expensive, there is room for improvement in simplifying the apparatus.

Among the conventional methods, the mold release material sticking method is awarded because it has the simplest equipment and a high-purity product is obtained, and is a method used for a water-absorbent resin (for example, see Patent Document 3). A method (for example, see Patent Document 4) used for a water-soluble resin is disclosed. However, in these methods, since heat removal is not sufficient, it is difficult to produce a high molecular weight product. Therefore, when trying to obtain a high molecular weight polymer, low-temperature cooling water is required. Usually, in order to make the cooling water sufficiently low in temperature, a refrigerator is required, and the equipment is expensive. There was room for ingenuity to manufacture inexpensively.

In these methods, the polymerization is usually carried out under an inert gas stream such as nitrogen gas at the time of polymerization, so that the dry inert gas comes into contact with the surface of the polymer. Moreover, when the cooling water which is not sufficiently lowered in temperature by the release material attaching method is used, the temperature of the polymer hydrous gel becomes abnormally high. For this reason, it is difficult to obtain a polymer with little residual monomer by the conventional release material pasting method, because the polymer surface is dried by an inert gas stream. Therefore, there has been room for contrivance to produce a polymer with little residual monomer at low cost.
JP-A-62-156102 (page 1-4) Japanese Patent Publication No.8-5926 (first page) JP-A-4-175319 (page 1-2) JP 61-155405 A (page 1-2)

The present invention has been made in view of the above situation, and an object of the present invention is to provide an acrylic acid (salt) -based polymer having high adhesiveness, low residual monomer, and high safety at low cost.

The present inventor has made various studies on a method for producing an acrylic acid (salt) -based water-soluble polymer, and paid attention to the fact that the production method by photopolymerization is industrially useful. When the photopolymerization is carried out on a substrate having a heat conductivity, it is sufficient even if the water of the comparatively low-temperature cooling tower that reaches approximately 35 ° C. in summer is used as it is due to excellent thermal conductivity. It has been found that the polymerization solution can be cooled. For this reason, in addition to the fact that a refrigerator is not required and the equipment cost can be kept low, the polymerization liquid can be sufficiently cooled even with relatively high-temperature cooling tower water, so acrylic acid having a high molecular weight. It has been found that (salt) -based water-soluble polymers can be produced at low cost. Further, it has been found that an acrylic acid (salt) -based water-soluble polymer having high adhesiveness can be easily peeled off by using a release material having a specific thickness made of a specific material. Furthermore, it has been found that by controlling photopolymerization below a specific peak temperature, a stable acrylic acid (salt) polymer having a high molecular weight and a low residual monomer content can be obtained. I came up with the idea that it can be solved on a case-by-case basis. Furthermore, it has been found that it can be suitably applied to various uses such as pharmaceuticals, paints, civil engineering / architecture, agriculture / horticulture, paints and adhesives, ceramics, manufacturing processes, and other general industrial use. It has been reached.

That is, the present invention is a method for producing an acrylic acid (salt) -based water-soluble polymer by performing photopolymerization of a monomer component on a substrate using a polymerization liquid containing the monomer component, Photopolymerization is controlled so that the primary peak temperature is 80 ° C. or lower on a base material having a release material with a thickness of 0.15 mm or less on a heat conductive base material with a thermal conductivity of 6 W / m · K or higher. Is a method for producing an acrylic acid (salt) -based water-soluble polymer.
The present invention is described in detail below.

In the method for producing an acrylic acid (salt) -based water-soluble polymer of the present invention, a monomer component is photopolymerized on a base material having a release material having a thickness of 0.15 mm or less on a heat conductive base material. Is.
As the heat conductive substrate, if it is made of a material that has thermal conductivity and is suitable for polymerization of monomer components on the substrate when cooled from the lower side of the substrate Well, those having a thermal conductivity of 6 W / m · K or more can be suitably used. By using the base material having such a thermal conductivity, the cooling water can be sufficiently cooled even when the temperature of the cooling water is relatively high. The thermal conductivity is more preferably 7 W / m · K or more, and still more preferably 8 W / m · K or more. As specific examples of the heat conductive substrate, steel, iron, copper and the like are suitable. Among these, steel is preferable. As a material of the steel heat conductive substrate, a known material such as SUS such as SUS301, SUS304, SUS316, SUS316L or carbon steel (CS) can be used. Among these, SUS301, SUS304, SUS316, and SUS316L are preferable, and it is particularly preferable to use a SUS-made heat conductive substrate such as SUS301.

The release material may be any material that can easily peel off the water-soluble polymer after photopolymerization, such as a fluororesin film, a fluororesin-impregnated glass cloth, a glass cloth adhesive tape, a Kapton adhesive tape, a fluororesin film, polyphenylene sulfite. Examples thereof include a film, a polyether film, a polyester film, an acetate cloth, a silicone rubber, a polypropylene film, and a glass cloth. Among these, a fluororesin film or a fluororesin impregnated glass cloth is preferable. By using a fluororesin film or a fluororesin-impregnated glass cloth as the release material, it is possible to easily peel off the acrylic acid (salt) -based water-soluble polymer having high adhesiveness.
The release material has a thickness of 0.15 mm or less. If it exceeds 0.15 mm, the release material may be too thick and heat removal through the heat conductive substrate may not be performed efficiently. More preferably, it is 0.13 or less, More preferably, it is 0.10 or less. The thickness of the release material refers to the thickness of the release material itself, and does not include the thickness of a paste material or the like for attaching the release material to the heat conductive substrate.

The photopolymerization is performed while controlling the primary peak temperature to be 80 ° C. or lower. According to photopolymerization, the light irradiation intensity and irradiation time can be easily set and changed, so that the polymerization time can be further shortened and the productivity can be improved. In the present invention, the peak temperature is a peak temperature (maximum value) formed when the temperature of the reaction solution rises and falls or maintains the same temperature after the start of polymerization, and the primary peak temperature is the peak temperature of the peak. If it is possible, it means the peak temperature, and if there are a plurality of peak temperatures, it means the first peak temperature. That is, when the time is plotted on the horizontal axis and the temperature of the reaction solution is plotted on the vertical axis, the peak that appears first after the start of polymerization among the peaks formed when the temperature rises and falls is taken as the primary peak. For example, in the case of a temperature pattern in the case of polymerization with a constant light intensity, usually only one peak can be formed, so this peak is set as the primary peak. When the light intensity is increased during the polymerization, the second peak may appear along with the rapid polymerization of the residual monomer after increasing the light intensity following the first peak. In this case, The first peak appears as the primary peak.

When the primary peak temperature (primary peak temperature of the polymerization solution) exceeds 80 ° C., the polymerization reaction proceeds excessively, and the molecular weight of the resulting acrylic acid (salt) water-soluble polymer is not sufficiently high. In addition, there is a possibility that the monomer remaining in the polymer cannot be sufficiently reduced. More preferably, it is 75 degrees C or less, More preferably, it is 70 degrees C or less. The lower limit of the primary peak temperature of the polymerization solution may be a temperature at which the molecular weight is sufficient, and is preferably 30 ° C. or higher. More preferably, it is 35 degreeC or more, More preferably, it is 40 degreeC or more.

As the polymerization method in the photopolymerization, a method by aqueous solution polymerization in which the reaction solution is in the form of an aqueous solution is preferable. In the aqueous solution polymerization, it is preferable to perform the polymerization in a state in which dissolved oxygen dissolved in the aqueous solution is removed in advance by, for example, a method of bubbling nitrogen gas.
In the aqueous solution polymerization, the layer thickness of the aqueous solution containing the monomer component is preferably 5 to 50 mm. If the layer thickness is less than 5 mm or more than 50 mm, the monomer component remains in the resulting polymer and the molecular weight of the polymer may not be sufficiently high. More preferably, it is 8-30 mm, More preferably, it is 10-20 mm.

In the photopolymerization, the polymerization operation method may be batch or continuous, but a method by static polymerization is preferred. There is a belt polymerization method as a particularly preferable polymerization method, and this polymerization method is a single polymerization form of standing polymerization and continuous. Thus, the photopolymerization is preferably performed using a belt polymerization machine using a belt as a heat conductive substrate. By using a belt polymerization machine, there is an advantage that continuous production becomes possible.
The belt is not particularly limited as long as it has a release material having a thickness of 0.15 mm or less on a heat conductive substrate. Thus, a method for producing an acrylic acid (salt) -based water-soluble polymer by carrying out photopolymerization of monomer components on a belt using a belt polymerization machine, wherein the belt polymerization machine has a heat transfer property. An acrylic acid (salt) -based water-soluble polymer comprising a belt having a release material having a thickness of 0.15 mm or less on a substrate, and wherein the photopolymerization is performed so that the peak temperature is 80 ° C. or less. This manufacturing method is also one of the preferred embodiments of the present invention.

The monomer component in the present invention forms an acrylic acid (salt) -based water-soluble polymer by photopolymerization, and contains acrylic acid and / or acrylate as a main component. As the acrylate, neutralized product obtained by neutralizing acrylic acid with monovalent metal, divalent metal, ammonia, organic amine, etc., that is, sodium acrylate, potassium acrylate, magnesium acrylate, calcium acrylate, acrylic Ammonium acid is preferred. Among these, sodium acrylate is preferable. The above acrylic acid (salt) monomers may be used alone or in combination of two or more.
The monomer component of the present invention is preferably such that the amount of the monomer component, which is a raw material used, is 100 mol%, and the acrylic acid (salt) monomer is used in an amount of 50 mol% or more. More preferably, it is 60 mol% or more, More preferably, it is 70 mol% or more, Especially preferably, it is 80 mol% or more, Most preferably, it is 90 mol% or more. Monomers other than acrylic acid (salt) monomers are preferably 50 mol% or less in the total monomer components. More preferably, it is 40 mol% or less, More preferably, it is 30 mol% or less, Especially preferably, it is 20 mol% or less, Most preferably, it is 10 mol% or less.

The monomer other than acrylic acid (salt) is not particularly limited. For example, α-hydroxy (meth) acrylic acid, crotonic acid, methacrylic acid, and these acid-type monomers are monovalent metals, Unsaturated monocarboxylic acid monomers such as neutralized products obtained by neutralization with divalent metals, ammonia, organic amines, etc .; maleic acid, fumaric acid, itaconic acid, citraconic acid, and their acid forms Unsaturated dicarboxylic acid monomer such as neutralized product obtained by neutralizing the body with monovalent metal, divalent metal, ammonia, organic amine, etc .; vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, styrene sulfone Acid, 2- (meth) acrylamido-2-methylpropanesulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid, sulfoethyl (meth) acrylate, sulfopropyl (meth) acrylate , 2-hydroxysulfopropyl (meth) acrylate, sulfoethylmaleimide, and neutralized products obtained by neutralizing these acid monomers with monovalent metals, divalent metals, ammonia, organic amines, etc. Unsaturated sulfonic acid monomers; (meth) acrylamide methanephosphonic acid, 2- (meth) acrylamide-2-methylpropanephosphonic acid, and these acid-type monomers as monovalent metal, divalent metal, ammonia Unsaturated phosphonic acid monomers such as neutralized products obtained by neutralization with organic amines; (meth) acrylamide monomers such as (meth) acrylamide and t-butyl (meth) acrylamide; (meth) Hydrophobic monomers such as acrylic ester, styrene, 2-methylstyrene, vinyl acetate; 3-methyl-2-buten-1-ol (prenol), 3-methyl-3-butene -1-ol (isoprenol), 2-methyl-3-buten-2-ol (isoprene alcohol), 2-hydroxyethyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, polyethylene Hydroxyl monoisoprenol ether, polypropylene glycol monoisoprenol ether, polyethylene glycol monoallyl ether, polypropylene glycol monoallyl ether, glycerol monoallyl ether, N-methylol (meth) acrylamide, glycerol mono (meth) acrylate, vinyl alcohol, etc. Unsaturated monomers having dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, etc. On monomers; (meth) nitriles such as acrylonitrile-based monomer, and the like.

The concentration of the monomer component in the polymerization solution at the start of polymerization is preferably 28 to 60% by mass. If the concentration of the monomer component is less than 28% by mass, the concentration of the monomer component may be too low to cause sufficient polymerization, and if it exceeds 60% by mass, the polymerization reaction may run away. . More preferably, it is 32-55 mass%. More preferably, it is 34-50 mass%. In addition, the said polymerization liquid is a solution containing a monomer, and the solution diluted with solvents, such as water, is preferable. The concentration of the monomer component in the polymerization solution is obtained by setting the reaction solution containing all the monomer components used for polymerization as 100% by mass.
The neutralization degree of the monomer or polymer in the polymerization reaction solution is preferably 0 to 60 mol%, and the pH of the reaction solution is preferably strongly acidic.

In the production method described above, the primary peak temperature of the polymerization liquid is controlled to be 80 ° C. or lower. The primary peak temperature is controlled by bringing the lower surface of the heat conductive substrate into contact with water. Preferably it is done. The bottom surface of the heat conductive substrate having excellent thermal conductivity can be cooled by contacting with water, and the polymerization liquid can be sufficiently cooled through a thin release material of 0.15 mm or less that can sufficiently secure the thermal conductivity. it can.
Although the temperature of the water which contacts the lower surface of the said heat conductive base material will not be specifically limited if it is the temperature which can cool a polymerization liquid, It is preferable that it is 20-40 degreeC. In the present invention, in order to polymerize on a specific thin release material affixed on a substrate having excellent thermal conductivity, it is possible to sufficiently cool the polymerization liquid even when using comparatively low and high temperature cooling water, An acrylic acid (salt) polymer having a high molecular weight and a small residual monomer content can be obtained at low cost. Usually, in summer, the upper limit of the water temperature in the cooling tower is about 35 ° C. According to the manufacturing method of the present invention, water having a relatively high temperature of about 35 ° C. can be used as the cooling water, so that a refrigerator for cooling the cooling water is not required and the equipment cost is reduced. The temperature of the water is preferably 25 to 38 ° C, and more preferably 30 to 35 ° C.

The primary peak temperature is preferably controlled by using near ultraviolet rays of 10 W / m ² or less. If it exceeds 10 W / m ² , the amount of light is too high and the primary peak temperature exceeds 80 ° C. As a result, a sufficiently high molecular weight polymer cannot be obtained, and a large amount of insoluble matter may be generated. More preferably, it is 8 W / m ² or less, and further preferably 6 W / m ² or less. The lower limit is preferably 1 W / m ² or more. If it is less than 1 W / m ² , the polymerization reaction may not be promoted sufficiently. More preferably, it is 1.5 W / m ² or more, and further preferably 2 W / m ² or more.

The near-ultraviolet rays of 10 W / m ² or less preferably have an irradiation time of 10 minutes or more. If the irradiation time is less than 10 minutes, the primary peak temperature may exceed 80 ° C., so that a high molecular weight polymer may not be obtained. More preferably, it is 15 minutes or more, More preferably, it is 20 minutes or more. The upper limit of the irradiation time is preferably less than 100 minutes, and if it is 100 minutes or more, the productivity is lowered and the effects of the present invention cannot be sufficiently obtained. More preferably, it is less than 80 minutes, More preferably, it is less than 60 minutes.

The photopolymerization preferably includes a step of polymerizing by irradiating near ultraviolet rays of 10 W / m ² or less, and a step of completing the polymerization by irradiating near ultraviolet rays exceeding 10 W / m ² . By irradiating near-ultraviolet rays of different intensities in two stages in this way, the polymerization of the monomer is promoted, and the resulting polymer can have a sufficiently high molecular weight. The amount of the monomer remaining in the resin can be reduced, and the resulting acrylic acid (salt) -based water-soluble polymer can be of high quality. In the step of polymerizing by irradiation with near ultraviolet rays of 10 W / m ² or less (during the primary reaction), light of 0 W / m ² and 10 W / m ² or less is constantly irradiated, and the near ultraviolet rays exceeding 10 W / m ^2. In the step of completing the polymerization by irradiating (at the time of the secondary reaction), it is preferable that light exceeding 10 W / m ² is constantly irradiated. Therefore, any light with an intensity in the range of 10 W / m ² or less may be irradiated during the primary reaction, and any light with an intensity in the range exceeding 10 W / m ² during the secondary reaction. May be. The light intensity is not particularly limited as long as it satisfies such an intensity range. For example, a method of repeatedly changing the light irradiation intensity between strong and weak may be used.

When the near-ultraviolet ray exceeding 10 W / m ² irradiated in the second stage is 10 W / m ² or less, the amount of light may be too low to reduce the remaining monomer sufficiently. More preferably, there shall exceed 12W / ^{m 2,} more preferably in excess of 15W / ^{m 2.} The upper limit is preferably 100 W / m ² or less. If it exceeds 100 W / m ² , the irradiation intensity is too strong, and the product may be colored, or a sufficiently high molecular weight polymer may not be obtained. More preferably, it is 80 W / m < ² > or less, More preferably, it is 50 W / m < ² > or less.
The irradiation time of the near-ultraviolet ray in the second stage is not particularly limited as long as the remaining monomer can be sufficiently reduced, but is preferably 1 to 30 minutes. More preferably, it is 3-20 minutes, More preferably, it is 5-15 minutes.

As the lamp that emits near ultraviolet rays in the polymerization step, for example, incandescent bulbs; halogen bulbs; fluorescent lamps and metal halide lamps, high pressure sodium lamps, low pressure sodium lamps, mercury lamps and other HID (HIGH INTERNITY DISCHARGE LAMPS) lamps are preferable. . Among them, a HID lamp is preferable, and a mercury lamp such as a fluorescent mercury lamp, an incandescent fluorescent mercury lamp, a transparent mercury lamp, a chalkless mercury lamp, and a black light mercury lamp is more preferable. In particular, a black light mercury lamp that emits only near ultraviolet rays is particularly preferable. Further, the wavelength region of near ultraviolet rays is preferably 300 nm or more and preferably 500 nm or less. When ultraviolet rays having a wavelength of less than 300 nm are irradiated, the polymerization reaction may be accelerated, and an acrylate polymer having a high viscosity and a small amount of residual monomer may not be obtained.

In the present specification, the near-ultraviolet light irradiation intensity is the light irradiation intensity measured on the upper surface of the reaction liquid irradiated with near-ultraviolet light, that is, the reaction liquid surface. The light irradiation intensity can be measured with the following light meter.
Apparatus: UV meter Manufacturer: Custom Co., Ltd. Model: Main unit UVA-365
Sensor: UV sensor (Spectra response 300nm to 400nm)
In addition, as a problem related to the intensity of near-ultraviolet rays, there is a problem that polymerization control becomes difficult if the intensity is too strong, that is, a quality problem that bumping problem and insoluble matter tend to increase. First, the primary reaction is performed at a reduced strength, and then the strength is increased, which is advantageous for such a problem.

As a method of changing the intensity of near ultraviolet rays, a method using ultraviolet lamps having different irradiation intensities, a method of increasing or decreasing the irradiation intensity by inverter control, a method of installing a light reducing plate between the ultraviolet lamp and the polymerization liquid, etc. Thus, the irradiation intensity of near ultraviolet rays can be changed. At the laboratory level, for example, as shown in FIGS. 3 and 4, an ultraviolet lamp with different irradiation intensity is used, and the irradiation intensity is increased by adding a reflective shade to the ultraviolet lamp at the second stage of irradiation. Can be changed. In addition, when the belt polymerization method is used as the polymerization step, the near-ultraviolet irradiation intensity can be changed by installing a light-reducing plate such as a punching metal between the belt and the ultraviolet lamp. Even in the case of using a plurality of different light-attenuating plates, the irradiation intensity can be changed as appropriate, so near-ultraviolet rays having different intensities can be irradiated in two stages, and the method of the present invention Can be used.

An embodiment of the method for producing a (meth) acrylic acid-based water-soluble polymer of the present invention will be described with reference to FIG. In FIG. 1, 6 is an arrow indicating the direction of light irradiation, and 7 is an arrow indicating the belt driving direction.
FIG. 1 shows a form in which a light-reducing plate is provided. A light-reducing plate 3 is installed between a continuous base belt 1 and an ultraviolet lamp 2. In this case, by operating the belt 1, the reaction solution moves under the light-reducing plate 3. When near ultraviolet rays of a certain intensity are irradiated here by the ultraviolet lamp 2, when moving the portion where the light reducing plate 3 is installed, near ultraviolet rays (near ultraviolet rays of 10 W / m ² or less) with reduced light irradiation intensity are generated. When the reaction solution is irradiated and moved in a portion where the light reducing plate 3 is not installed, the reaction solution is irradiated with near-ultraviolet rays having a constant intensity (near-ultraviolet exceeding 10 W / m ² ). Accordingly, the light irradiation intensity can be changed by moving the reaction solution by the belt 1 and passing through the portion where the light reducing plate 3 is provided and the portion where the light reducing plate 3 is not provided.

The width on the belt traveling direction side is preferably 10 cm or more, and more preferably 3 m or less. More preferably, it is 20 cm or more, More preferably, it is 30 cm or more, More preferably, it is 2 m or less, More preferably, it is 1.5 m or less.

In the polymerization step performed using the polymerization solution, it is preferable to perform polymerization using a photopolymerization initiator. By polymerizing using a photopolymerization initiator, the polymer can have a high viscosity, and the amount of the remaining monomer can be reduced. In this case, it is preferable to mix a photopolymerization initiator in the polymerization solution.
The photopolymerization initiator is not particularly limited as long as it exhibits its effects, but an azo initiator is preferable. As the azo initiator, 2,2′-azobis (2-amidinopropane), 2,2′-azobis (N, N′-dimethyleneisobutylamidine), 2,2′-azobis [2- (5- Methyl-2-imidazolin-2-yl) propane], 1,1′-azobis (1-amidino-1-cyclopropylethane), 2,2′-azobis (2-amidino-4-methylpentane), 2, 2'-azobis (2-N-phenylaminoamidinopropane), 2,2'-azobis (1-imino-1-ethylamino-2-methylpropane), 2,2'-azobis (1-allylamino-1- Imino-2-methylbutane), 2,2'-azobis (2-N-cyclohexylamidinopropane), 2,2'-azobis (2-N-benzylamidinopropane) and its hydrochloric acid, sulfuric acid, vinegar 4,4'-azobis (4-cyanovaleric acid) and its alkali metal salts, ammonium salts, amine salts, 2- (carbamoylazo) isobutyronitrile, 2,2'-azobis (isobutyramide), etc. 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2'-azobis [2-methyl-N- (1,1'-bis (hydroxymethyl) ethyl) propion Amide], 2,2′-azobis [2-methyl-N-1,1′-bis (hydroxyethyl) propionamide] and the like are preferable. Among these, azo-based water-soluble initiators such as 2,2′-azobis-2-amidinopropane dihydrochloride are more preferable. As described above, in the polymerization step, a method for producing an acrylate polymer in which the polymerization initiator is an azo water-soluble initiator. An azo water-soluble initiator is also a preferred embodiment of the present invention.

As the photopolymerization initiator, a photopolymerization initiator other than the azo-based water-soluble initiator can be used. Such photopolymerization initiators include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propane. Eutectic mixture of -1-one, 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184) and benzophenone, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1 -Propan-1-one, 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl)- Butanone-1,2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 (Irgacure 36) ) And 2,2-dimethoxy-1,2-diphenylethane-1-one (Irgacure 651), bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (2 , 6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide (CGI403) and 2-hydroxy-2-methyl-1-phenyl-propan-1-one (Darocur 1173) A mixture of bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide (CGI403) and 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184), bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine 1: 1 mixture of oxide (CGI403) and 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184), 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and 2-hydroxy-2-methyl- 1: 1 liquid mixture with 1-phenyl-propan-1-one (Darocur 1173), bis (η ⁵ -2,4-cyclopentadien-1-yl) -bis (2,6-difluoro-3- ( 1H-pyrrol-1-yl) -phenyl) titanium,

Oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone], eutectic mixture of 2,4,6-trimethylbenzophenone and 4-methylbenzophenone, 4-methylbenzophenone and Liquid mixture with benzophenone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone] and methylbenzophenone derivative Liquid mixture, 1- [4- (4-benzoylphenylsulfanyl) phenyl] -2-methyl-2- (4-methylphenylsulfanyl) propan-1-one, benzyldimethyl ketal, 2-hydroxy-2-methyl-1 -Phenyl-1-propanone, α-hydroxycyclohexyl-fur Nyl ketone, ethyl 4-dimethylaminobenzoate, acrylated amine synergist, benzoin (iso- and n-) butyl ester, acrylic sulfonium (mono, di) hexafluorophosphate, 2-isopropylthioxanthone, 4-benzoyl-4 ' -Methyldiphenyl sulfide, 2-butoxyethyl 4- (dimethylamino) benzoate, ethyl 4- (dimethylamino) benzoate,

Examples thereof include benzoin, benzoin alkyl ether, benzoin hydroxyalkyl ether, diacetyl and derivatives thereof, anthraquinone and derivatives thereof, diphenyl disulfide and derivatives thereof, benzophenone and derivatives thereof, and benzyl and derivatives thereof. These may be used alone or in combination of two or more.

The amount of the photopolymerization initiator used is preferably 0.0001 g or more and more preferably 1 g or less with respect to 1 mol of the monomer component used for polymerization. Thereby, the molecular weight and polymerization rate of the acrylic acid (salt) water-soluble polymer can be made sufficiently high. More preferably, it is 0.001 g or more and 0.5 g or less.

In the present invention, it is preferable to use a thermal polymerization initiator in combination with a photopolymerization initiator. By using the thermal polymerization initiator in combination, the amount of the remaining monomer can be reduced.
As the thermal polymerization initiator, a wide range of polymerization initiators soluble in an aqueous medium can be used. For example, hydrogen peroxide; persulfates such as ammonium persulfate, sodium persulfate, potassium persulfate; 2 Azo compounds such as 2,4'-azobis (2-amidinopropane) dihydrochloride, 4,4'-azobis- (4-cyanovaleric acid), 2,2'-azobisisobutyronitrile; An organic peroxide such as succinic acid is preferred. These can use 1 type (s) or 2 or more types. Among these, persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate, hydrogen peroxide, and the like are more preferable, and ammonium persulfate is more preferable.

As the usage-amount of the said thermal-polymerization initiator, 0.01-1 mass% is preferable with respect to 100 mass% of said monomer components. In order to accelerate the decomposition of these thermal polymerization initiators, an organic or inorganic reducing agent can be used in combination.
When using a reducing agent, 0.01-3 mass% is preferable with respect to 100 mass% of monomer components.

In the polymerization step, a chain transfer agent may be used as necessary. Examples of the chain transfer agent include sulfur-containing compounds such as sulfite (hydrogen) salts, thioglycolic acid, thioacetic acid, and mercaptoethanol; phosphorous acid compounds such as phosphorous acid and sodium phosphite; hypophosphorous acid and sodium hypophosphite Hypophosphorous acid compounds such as: alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol and n-butyl alcohol. These may be used alone or in combination of two or more. Among these, hypophosphorous acid compounds are preferable. More preferred is sodium hypophosphite.
The amount of the chain transfer agent used may be appropriately set depending on the polymerization concentration, a combination with a photopolymerization initiator, and the like, but is preferably 0.0001 g or more with respect to 1 mol of the monomer component used for the polymerization. Moreover, 0.2 g or less is preferable. 0.001 g or more and 0.1 g or less is more preferable, and 0.005 g or more and 0.05 g or less is particularly preferable.

As the polymerization solvent, water is preferably used. In addition to water, a hydrophilic organic solvent or the like may be used in combination as appropriate. As the hydrophilic organic solvent, alcohols such as methanol and ethanol; ketones such as acetone, lower ethers and the like are preferable.

The polymerization conditions in the polymerization step may be set as appropriate according to the composition of the monomer component, the type of photopolymerization initiator and the type and amount of thermal polymerization initiator added as necessary, The concentration of the monomer component in the reaction solution (monomer concentration) is 28% by mass or more, 60% by mass or less, more preferably 32 to 55% by mass, and still more preferably. Is 34-50 mass%. The above polymerization start time is when a reaction liquid containing a predetermined amount of monomer components is prepared and polymerized for polymerization. By increasing the monomer concentration, the thickening action of the polymer can be further enhanced. Further, it is more advantageous in terms of improving productivity. However, when the monomer concentration is too high, the insoluble content increases, which is not preferable. Further, the primary polymerization peak temperature is preferably within the above-mentioned range, but the temperature at which the polymerization is started is preferably 50 ° C. or lower. More preferably, it is 35 degrees C or less, More preferably, it is 30 degrees C or less. A lower polymerization initiation temperature is advantageous in terms of productivity because there is no danger based on abnormal reactions such as bumping, and a reaction at a high concentration is facilitated. The polymerization temperature is also an effective polymerization condition for improving the physical properties of the resulting acrylic acid (salt) -based water-soluble polymer.

In the production method of the present invention, an acrylic acid (salt) -based water-soluble polymer that is a dried product can be obtained by drying the polymer obtained by the polymerization step preferably at 50 ° C to 220 ° C. As a method for drying the polymer, for example, it is preferable to increase the surface area of the polymer or to dry under reduced pressure by a method such as cutting the polymer so as to be easily dried. If the drying temperature is lower than 50 ° C., the polymer may not be sufficiently dried. If the drying temperature is higher than 220 ° C., thermal crosslinking of the polymer may occur, and the insoluble matter may increase. Moreover, when higher than 240 degreeC, there exists a possibility that the cutting | disconnection of the principal chain of a polymer and a crosslinking point may occur. Therefore, a more preferable drying temperature is 100 to 210 ° C. More preferably, it is 150-200 degreeC. In addition, what is necessary is just to set suitably as drying time according to the moisture content, drying temperature, etc. which are contained in a polymer.

The neutralization degree of the acrylic acid (salt) -based water-soluble polymer obtained by the production method of the present invention is preferably 0 to 60 mol%. The degree of neutralization of the acrylic acid (salt) -based water-soluble polymer is neutralized when the sum of the acid groups of the acrylate polymer and the groups in the neutralized state is 100 mol%. This means the content (neutralization degree) of the group in a dry state. In general, the lower the degree of neutralization, the worse the releasability. However, according to the present invention, there is an advantage that the polymer having the low neutralization degree can be easily released. More preferably, it is 50 mol% or less, More preferably, it is 40 mol% or less.

The group in the neutralized form is a group in which a dissociable hydrogen ion in an acid group is substituted with another cation. Therefore, the neutralization degree can be obtained by, for example, the monomer component forming an acrylic acid (salt) -based water-soluble polymer being x mol of acrylic acid, y mol of sodium acrylate as a salt of acrylic acid, and nonionic properties. Assuming that n moles of the monomer are contained and all of them are polymerized, the nonionic monomer is not ionic and is not in a neutralized form.

In the above formula, the denominator is the sum of the number of moles of the acid group amount used for the production of the acrylic acid (salt) -based water-soluble polymer and the neutralized base amount. A molecule is a neutralized form of a base weight. According to the above formula, the degree of neutralization (the content ratio of the neutralized group) can be obtained as mol%.

In the method for producing an acrylic acid (salt) water-soluble polymer, the residual monomer concentration of the acrylic acid (salt) water-soluble polymer is preferably 1% by mass or less. In the acrylic acid (salt) -based water-soluble polymer, if the residual monomer concentration (residual monomer concentration) exceeds 1% by mass, the quality may be low, and the effects of the present invention may not be exhibited sufficiently. More preferably, it is 0.5 mass% or less, More preferably, it is 0.3 mass% or less.
The residual monomer concentration (residual monomer concentration) is the polyacrylic acid described in Food Additives 7th Edition, 436, 437, or Feed Additive Component Specification, etc., 10th Edition, 239, 240 It is measured by the following method described in the section of sodium purity test. When using an acrylic acid (salt) -based water-soluble polymer for food additives or feed additives, when the amount of residual monomer is determined by the following method, the amount must be 1% or less. .

Method for measuring residual monomer (bromine addition method)
About 1 g of this product (polymer) is weighed accurately, put in a 300 ml iodine bottle, add 100 ml of water, and leave it for about 24 hours with occasional shaking to dissolve. To this solution, add exactly 10 ml of potassium bromate / potassium bromide test solution, shake well, add 10 ml of hydrochloric acid quickly, seal immediately and shake again well, then potassium iodide is added to the top of the iodine bottle. Add about 20 ml of the test solution and leave it in the dark for 20 minutes. Next, loosen the stopper and pour the potassium iodide reagent solution, immediately seal it and shake well, then titrate with 0.1 mol / l sodium thiosulfate solution (indicator starch reagent solution 2 mL). Separately, a blank test is performed in the same manner, and the content is obtained by the following formula.

Where a: consumption of 0.1 mol / l sodium thiosulfate solution in the blank test (ml)
b: Consumption of 0.1 mol / 1 sodium thiosulfate solution in this test (ml)

The insoluble matter is preferably 2% by mass or less. In the acrylic acid (salt) -based water-soluble polymer, when the insoluble content exceeds 2% by mass, the quality is low, and the effects of the present invention may not be sufficiently exhibited. More preferably, it is 1 mass% or less, More preferably, it is 0.8 mass% or less, Most preferably, it is 0.6 mass% or less. Most preferably, it is not included.
By adding 1.0 g of an acrylic acid (salt) -based water-soluble polymer to 499 g of ion-exchanged water and stirring for 50 minutes, the insoluble matter was adjusted to 25 ° C. and filtered using a 500 μm mesh sieve. Take out the insoluble matter in the water-containing state, and the following formula:
Insoluble matter (mass%) = {mass of insoluble matter (g) / 500 (g)} × 100
Is a value calculated based on In addition, in this specification, an insoluble content shall be a value measured within 1 minute after filtering the acrylic acid (salt) type | system | group water-soluble polymer in aqueous solution with the said filter. In addition, filtration and weighing are performed under conditions of 25 ° C. and humidity of 60% or more.

The method for producing an acrylic acid (salt) -based water-soluble polymer of the present invention comprises the above-described structure, and produces an acrylic acid (salt) -based polymer with high adhesiveness, low residual monomer and high safety at low cost. Acrylic acid (salt) -based water used as a thickener, adhesive, flocculant, hygroscopic agent, desiccant, etc. in pharmaceutical, paint, civil engineering / architecture, and other general industrial applications A suitable polymer can be produced.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples. Unless otherwise specified, “part” means “part by weight” and “%” means “mass%”.

Example 1
In a beaker with a capacity of 500 ml, acrylic acid 247.9 g, ion-exchanged water 247.9 g, and Darocur (DC) 1173 as photopolymerization initiator (Ciba Specialty Chemicals, chemical name; 2-hydroxy-2-methyl-1-phenyl) 2.1 g of 5% acrylic acid solution of propan-1-one) and 2.1 g of 5% aqueous sodium hypophosphite solution were added.
The acrylic acid concentration in the reaction solution was 50%, and the amount of Darocur 1173 used was 0.03 g with respect to 1 mol of acrylic acid. Moreover, the usage-amount of sodium hypophosphite was a ratio of 0.03g with respect to 1 mol of acrylic acid. After stirring and mixing, a Teflon (registered trademark) film having a thickness of 0.08 mm (adhesive is a silicone system having a thickness of 0.05 mm) is attached to the bottom surface shown in FIG. The water adjusted to ° C. was introduced into a polymerization vessel made of SUS304 through which the water was circulated.
After covering the polymerization vessel with Saran wrap, the dissolved oxygen in the reaction solution was removed by bubbling nitrogen.

Next, as shown in FIG. 3, a black light mercury lamp (H100BL-L, manufactured by Toshiba Lighting & Technology Co., Ltd.) was irradiated from the top having a height of 35 cm. The light intensity is 3.7 w / m ² at the upper surface position of the reaction solution. For the light intensity, the above-mentioned light meter (UV meter (model UVA-365) manufactured by Custom Inc.) was used.
As soon as the light irradiation was started, the polymerization started and reached the primary peak temperature of 73 ° C. after 16 minutes.
Then, after standing for 3 minutes, as shown in FIG. 4, irradiation was performed for 7 minutes by irradiation with a black light mercury lamp with a reflective shade (made by Toshiba Lighting & Technology Co., Ltd., H400BL-L) vertically oriented from the top of 15.5 cm in height. Was completed. The light intensity is 17 w / m ² at the upper surface position of the reaction solution.
When the gel polymer thus obtained was taken out from the polymerization vessel, it was easily released without any polymer remaining attached to the vessel. Next, the gel polymer was finely cut with scissors and then dried under reduced pressure at 80 ° C. Next, after pulverizing with a table pulverizer, it was classified so as to be 40 mesh pass to obtain a polymer (1) made of polyacrylic acid.

The solution viscosity of the polymer (1) was measured as follows.
(Measurement method of solution viscosity)
The viscosity was determined by adding 1.0 g of the polymer (1) to 499 g of ion-exchanged water, stirring for 50 minutes, setting to 25 ° C., and measuring with a B-type viscometer (reading after 10 minutes at 30 rpm). .
Further, the residual monomer of the polymer (1) was measured according to the above-described residual monomer measurement method ([bromine addition method]). The solution viscosity of the polymer (1) was 15 mPa · s, and the residual monomer was 0.2 mol%.

Examples 2-4
Polymers (2) to (4) made of polyacrylic acid were obtained in the same manner as in Example 1 except that the release material shown in Table 1 was used. In the same manner as in Example 1, the mold was easily released without any polymer remaining on the container.
The solution viscosities and residual monomers of the polymers (2) to (4) were measured in the same manner as in Example 1, and the results are shown in Table 1.

Example 5
76.1 g of acrylic acid, 402.6 g of 37% aqueous solution of sodium acrylate, 16.58 g of ion-exchanged water, 5% of 2,2 ′-(2-amidinopropane) dihydrochloride as a photopolymerization initiator in a 500 ml beaker 2.13 g of aqueous solution and 2.64 g of 1% aqueous sodium hypophosphite solution were added.
The concentration of the monomer consisting of acrylic acid and sodium acrylate in the reaction solution was 50%, and the degree of neutralization was 60 mol%. The amount of 2,2 ′-(2-amidinopropane) dihydrochloride used was 0.04 g per mole of monomer. Moreover, the usage-amount of sodium hypophosphite was the ratio of 0.01g with respect to 1 mol of monomers. By polymerizing the polymerization solution under the same polymerization conditions as in Example 1, a polymer (5) composed of a partially neutralized polyacrylic acid was obtained.
In the same manner as in Example 1, the mold was easily released without any polymer remaining on the container.
The solution viscosity and residual monomer of the polymer (5) were measured in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Examples 1 and 2
Comparative polymers (1) to (2) made of polyacrylic acid were obtained in the same manner as in Example 1 except that the release material shown in Table 2 was used.
The solution viscosity and residual monomer (1) to (2) of the comparative polymer were measured in the same manner as in Example 1, and the results are shown in Table 2.

Comparative Example 3
A comparative polymer (3) composed of a partially neutralized polyacrylic acid was obtained in the same manner as in Example 5 except that the release material shown in Table 2 was used.
The solution viscosity and residual monomer (3) of the comparative polymer were measured in the same manner as in Example 5, and the results are shown in Table 2.

FIG. 1 is a conceptual diagram showing one embodiment of a method for producing a (meth) acrylic acid-based water-soluble polymer of the present invention. FIG. 2 is a diagram showing an embodiment of a polymerization apparatus for producing the acrylic acid (salt) -based water-soluble polymer of the present invention. FIG. 3 is a diagram showing an embodiment of the first photopolymerization step in the method for producing an acrylic acid (salt) -based water-soluble polymer of the present invention. FIG. 4 is a diagram showing an embodiment of a second-stage photopolymerization step in the method for producing an acrylic acid (salt) -based water-soluble polymer of the present invention.

Explanation of symbols

1: Continuous base material belt 2: Ultraviolet lamp 3: Light reduction plate 4: Release material 5: Heat transfer base material 6: Light irradiation direction 7: Belt driving direction 10: Saran wrap (manufactured by Asahi Kasei Kogyo Co., Ltd.)
11: 500 ml capacity beaker (SUS304)
12: Thermometer 13: Water (cooling water)
14: Water inlet 15: Water outlet 100: Blacklight mercury lamp (H100BL-L), Toshiba Lighting & Technology Corporation 101: Lamp holder, Toshiba Lighting & Technology Corporation 102: Blacklight mercury lamp (H400BL-L), Toshiba Lighting & Technology Corporation Company 103: Reflection shade (SN-4057T), Toshiba Lighting & Technology Corporation

Claims (8)

Photopolymerization of the monomer component is performed on the substrate using a polymerization liquid containing a monomer component in which the acrylic acid (salt) monomer is 80 mol% or more with respect to 100 mol% of the monomer component. A method for producing an acrylic acid (salt) -based water-soluble polymer having a neutralization degree of 0 to 60 mol%,
The photopolymerization is carried out on a base material obtained by directly attaching a release material having a thickness of 0.15 mm or less on a heat conductive base material having a thermal conductivity of 6 W / m · K or more, and a near ultraviolet ray of 10 W / m ² or less. conducted controlled to primary peak temperature is 80 ° C. or less by using,
The releasing member is a fluororesin film, a fluororesin-impregnated glass cloth, kapton adhesive tape, polyphenylene sulfide film, polyether film, a polyester film, acetate cloth, acrylic acid, wherein either Der Rukoto silicone rubber ( Salt) A method for producing a water-soluble polymer. 2. The method for producing an acrylic acid (salt) -based water-soluble polymer according to claim 1, wherein the photopolymerization is performed using a belt polymerization machine using a belt as a heat conductive substrate. The method for producing an acrylic acid (salt) water-soluble polymer according to claim 1, wherein the release material is a fluororesin film or a fluororesin-impregnated glass cloth. The acrylic acid (salt) -based water-soluble polymer according to any one of claims 1 to 3, wherein the concentration of the monomer component in the polymerization solution at the start of polymerization is 28 to 60% by mass. Manufacturing method. Control of the said primary peak temperature is performed by making the lower surface of a heat conductive base material contact with water, The manufacture of the acrylic acid (salt) type water-soluble polymer in any one of Claims 1-4 characterized by the above-mentioned. Method. The method for producing an acrylic acid (salt) -based water-soluble polymer according to claim 5, wherein the temperature of the water is 20 to 40 ° C. The photopolymerization includes a step of polymerizing by irradiating near ultraviolet rays of 10 W / m ² or less, and then a step of completing polymerization by irradiating near ultraviolet rays exceeding 10 W / m ^2. The manufacturing method of the acrylic acid (salt) type | system | group water-soluble polymer in any one of Claims 1-6. The acrylic acid (salt) -based water-soluble polymer has a residual monomer concentration of 1% by mass or less, according to any one of claims 1 to 7. Manufacturing method of coalescence.

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