JP4384904B2 - Acrylic syrup composition and method for producing acrylic resin plate - Google Patents

Description

  The present invention relates to an acrylic syrup composition and a method for producing an acrylic resin plate excellent in heat resistance, transparency and low water absorption.

  Acrylic resin plates are used in lenses, automobile parts, lighting parts, various electronic displays and the like because of their excellent optical properties. However, acrylic resin plates have the disadvantages that heat resistance is insufficient when heat treatment is performed at high temperatures, and that shape changes such as warpage are likely to occur due to water absorption.

  As a technique for improving the heat resistance of an acrylic resin plate, a method of introducing a crosslinked structure is known. For example, a method has been proposed in which a composition containing methyl methacrylate and polyfunctional (meth) acrylate is poured into a mold and cast-polymerized (see, for example, Patent Document 1). However, since the viscosity of the raw material is low in this method, there are many inconveniences and inconveniences in handling such as the raw material is likely to leak from the mold, and even if degassing operation is performed prior to polymerization, oxygen is easily dissolved again when it comes into contact with air. . Furthermore, the obtained resin molded product tends to warp due to water absorption.

  As a method for thickening the raw material, a method in which a polyfunctional (meth) acrylate of alkylene glycol is added to a composition comprising a methyl methacrylate homopolymer and methyl methacrylate and subjected to casting polymerization has been proposed (for example, , See Patent Document 2). In this method, the viscosity of the raw material can be increased, but the resulting resin molded product tends to warp due to water absorption.

In addition, for the purpose of improving heat resistance and shape stability, a method of casting polymerization of a polyfunctional (meth) acrylate having a tricyclodecane structure has been proposed (for example, see Patent Document 3). However, in this method, the viscosity of the raw material is low. Furthermore, as a method for increasing the viscosity of a raw material, a method in which an amorphous polyolefin is used in combination with a polyfunctional (meth) acrylate having a tricyclodecane structure has been proposed (for example, see Patent Document 4). However, this method tends to lower the transparency of the resin molded product obtained.
JP 2002-265538 A Japanese Patent Publication No. 4-75241 Japanese Patent Publication No. 4-30410 JP 2002-11739 A

  An object of the present invention is to provide a method for producing an acrylic resin plate excellent in heat resistance, transparency and low water absorption, and an acrylic syrup composition particularly useful for producing the acrylic resin plate. .

In the present invention, 4 to 64% by mass of a monoethylenically unsaturated monomer containing a methacrylic acid alkyl ester having an alkyl group having 1 to 4 carbon atoms, and a polyfunctional (meth) acrylate represented by the following general formula (1) and 35 to 95 wt%, and an acrylic syrup composition comprising a polymer 30% by mass (meth) containing acrylate units (co) of the following general formula (2), wherein the (co) A polymer is a composition which consists of 80-100 mass% of (meth) acrylate units shown by following General formula (2), and 0-20 mass% of methacrylic acid alkylester units which have a C1-C4 alkyl group. .

(In the formula, R ¹ represents H or CH _3. )

(Wherein R ² represents H or CH ₃ ).

Furthermore, the present invention relates to a monoethylenically unsaturated monomer 4 to 64% by mass containing a methacrylic acid alkyl ester having an alkyl group having 1 to 4 carbon atoms, and a polyfunctional (meth) represented by the general formula (1). acrylate 35 to 95% by weight, an acrylic-based syrup composition comprising a polymer 30% by mass (meth) containing acrylate units (co) that represented by the general formula (2), wherein the (co ) A composition comprising 80 to 100% by mass of a (meth) acrylate unit represented by the following general formula (2) and 0 to 20% by mass of a methacrylic acid alkyl ester unit having an alkyl group having 1 to 4 carbon atoms. It is a manufacturing method of the acrylic resin board which has the process of superposing | polymerizing and hardening.

  In the acrylic syrup composition of the present invention, since a specific composition is adopted, it is possible to improve inconvenience and inconvenience in handling during casting polymerization, and further, while maintaining the excellent optical properties of the acrylic resin, , Transparency and low water absorption can be greatly improved. In particular, by using this acrylic syrup composition in a method for producing an acrylic resin plate, an acrylic resin plate excellent in heat resistance, transparency and low water absorption can be easily produced.

  In this invention, content of the monoethylenically unsaturated monomer containing the methacrylic acid alkylester which has a C1-C4 alkyl group is 4-64 mass% in a composition. When the content is 4% by mass or more, the appearance is improved, and when it is 64% by mass or less, the heat resistance tends to be improved. Furthermore, this content is preferably 7 to 52% by mass, and more preferably 12 to 47% by mass. Moreover, when the total amount of the monoethylenically unsaturated monomer containing the methacrylic acid alkyl ester which has a C1-C4 alkyl group is 100 mass parts, the methacrylic acid alkyl ester which has a C1-C4 alkyl group Is preferably 50 parts by mass or more, and the ratio of other monoethylenically unsaturated monomers is preferably 50 parts by mass or less. When the ratio is set, transparency tends to be improved, and heat resistance may be further improved.

  Examples of the alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, and methacrylic acid. Examples include t-butyl acid. These can also be used in combination. Of these, methyl methacrylate is particularly preferred.

  Examples of monoethylenically unsaturated monomers other than methacrylic acid alkyl ester having an alkyl group having 1 to 4 carbon atoms include, for example, styrene, α-methylstyrene, acrylonitrile, acrylic acid, methacrylic acid, methyl acrylate, acrylic acid Ethyl, n-butyl acrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, isostearyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, isobornyl methacrylate, glycidyl methacrylate, tetrahydro methacrylate Examples include furfuryl, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, methoxyethyl methacrylate, ethoxyethyl methacrylate, and the like. These can also be used in combination. Among them, alkyl methacrylate having an alkyl group having 8 to 20 carbon atoms such as 2-ethylhexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, and isostearyl methacrylate is preferable from the viewpoint of a decrease in water absorption.

  The following general formula (1)

(In the formula, R ¹ represents H or CH _3. )
Content of polyfunctional (meth) acrylate shown by is 35-95 mass% in a composition. When this content is 35% by mass or more, the heat resistance is improved, and when it is 95% by mass or less, the appearance tends to be good. This content is preferably 45 to 90% by mass, and more preferably 50 to 85% by mass.

The compound represented by the general formula (1), for example, bis (oxymethyl) tricyclo [5,2,1,0 ^2,6] decane acrylate, bis (oxymethyl) tricyclo [5, 2, 1, 0 ^2,6 ] decanedimethacrylate. These can also be used in combination.

  The following general formula (2)

(In the formula, R ² represents H or CH _3. )
The content of the (co) polymer containing a (meth) acrylate unit represented by is 1 to 30% by mass in the composition. When the content is 1% by mass or more, the viscosity of the composition is increased, and the handleability during casting polymerization is improved. When the content is 30% by mass or less, impact resistance tends to be improved. It is preferable that it is 3-20 mass%. Here, the (co) polymer means a homopolymer or a copolymer.

In the present invention, when a conventional methyl methacrylate homopolymer is used by using a (co) polymer containing a (meth) acrylate unit represented by the general formula (2) in a specific range of blending amount Compared with, a molded article such as a resin plate having excellent physical properties such as transparency and low water absorption can be obtained.

The compound represented by the general formula (2), for example, tricyclo [5,2,1,0 ^2,6] dec-8-yl acrylate, tricyclo [5,2,1,0 ^2,6] deca - 8-yl methacrylate is mentioned. These can also be used in combination.

The (co) polymer containing the (meth) acrylate unit represented by the general formula (2) may contain other monomer units as necessary. The other monomers, Ru alkyl methacrylate units der having an alkyl group of 1 to 4 carbon atoms.

The content of methacrylic acid alkyl ester le Unit having an alkyl group of 1 to 4 carbon atoms, (co) in the polymer, Ru der 20 wt% or less. There exists a tendency for an external appearance to improve that this content is 20 mass% or less. Furthermore, the content is preferably 10% by mass or less. Further, by other monomer units is methacrylic acid alkyl ester unit having an alkyl group having 1 to 4 carbon atoms, tend to improve transparency, also it is the heat resistance is further improved.

Specific examples of the methacrylic acid alkyl ester le having an alkyl group of 1 to 4 carbon atoms, include the same ones listed above.

As a method for producing the (co) polymer containing the (meth) acrylate unit represented by the general formula (2), various conventionally known methods such as a bulk polymerization method and a suspension polymerization method can be used. .

  The syrup composition contains the above-described components as main components, but if necessary, further, a colorant, a release agent, an antioxidant, a stabilizer, an antistatic agent, an antibacterial agent, a flame retardant, and an impact resistance modifier. Polymerization regulators such as a quality agent, a light stabilizer, an ultraviolet absorber, a light diffusing agent, a polymerization inhibitor, a chain transfer agent, and terpinolene can be added.

  The acrylic syrup composition of the present invention is a composition containing each monomer and (co) polymer described above as main components. The syrup composition is preferably polymerized and cured and used as an acrylic resin plate.

The production method of the acrylic resin plate of the present invention includes the monoethylenically unsaturated monomer 4 to 64% by mass including the methacrylic acid alkyl ester having an alkyl group having 1 to 4 carbon atoms described above, and a general formula ( Acrylic syrup composition comprising 35 to 95% by mass of a polyfunctional (meth) acrylate represented by 1) and 1 to 30% by mass of a (co) polymer containing a (meth) acrylate unit represented by the general formula (2) The (co) polymer is a methacrylic acid alkyl ester unit having 0 to 100% by mass of a (meth) acrylate unit represented by the following general formula (2) and an alkyl group having 1 to 4 carbon atoms. A step of polymerizing and curing a composition comprising 20% by mass .

  Various conventionally known methods can be used as a polymerization and curing method for the syrup composition. Particularly preferred is a so-called casting polymerization method in which a polymerizable mixture is injected into a mold, polymerized and cured, and then peeled off from the mold.

  For polymerization of the syrup composition, conventionally known various radical initiators can be used. Specific examples of the radical initiator include t-butyl peroxypivalate, t-hexyl peroxypivalate, t-butyl peroxyneodecanoate, t-hexyl peroxyneodecanoate, t-butylperoxy. Isopropyl carbonate, t-hexylperoxyisopropyl monocarbonate, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2, Examples include 2'-azobisisobutyronitrile.

  Below, the method of the casting polymerization which uses methyl methacrylate as a methacrylic acid alkylester which has a C1-C4 alkyl group is illustrated. However, the present invention is not limited to this.

First, and methyl methacrylate, and bis (oxymethyl) tricyclo [5,2,1,0 ^2,6] Dekanji (meth) acrylate, tricyclo [5,2,1,0 ^2,6] dec-8-yl A (meth) acrylate polymer and another monoethylenically unsaturated monomer that can be copolymerized if necessary are charged into a suction bottle, stirred and dissolved to obtain a syrup composition. A polymerization initiator is added to the syrup composition, and vacuum deaeration is performed to obtain a polymerizable mixture. This polymerizable mixture is poured into a mold formed by sandwiching a gasket between a pair of tempered glass sheets, 15 to 120 minutes in a water bath at 60 to 90 ° C, and 30 to 180 minutes in an air furnace at 100 to 150 ° C. Acrylic resin plate can be obtained by performing polymerization and curing and peeling from the mold.

  Instead of this tempered glass sheet, for example, a mirror surface SUS sheet, a glass sheet with fine irregularities on the surface, or an endless belt made of mirror surface SUS that runs oppositely can be used as a mold. The polymerization temperature and time may be appropriately selected as desired.

  The thickness of the acrylic resin plate is preferably 0.5 to 5 mm. When the plate thickness is 0.5 mm or more, when the plate is produced by bulk polymerization, cracks tend not to occur when the acrylic resin plate is peeled from the mold. Moreover, when it is 5 mm or less, there is a tendency that it is difficult to break the plate during polymerization.

  The acrylic resin plate obtained by the present invention is greatly improved in heat resistance, transparency and low water absorption while maintaining the excellent optical properties of the acrylic resin. Such acrylic resin plates are, for example, peripheral materials for exothermic light sources such as incandescent lamp covers and halogen lamp covers, parts of heating household appliances such as clothes dryers, microwave ovens, ovens, eyeglass lenses, sunglasses lenses, and cameras. In-vehicle materials such as lenses, video camera lenses, goggles lenses, contact lenses and other optical lenses, meter covers and other in-vehicle parts, in-vehicle audio equipment parts, in-vehicle display device parts, in-vehicle navigation system parts, Furthermore, it can be used for various display members such as a front plate of various display devices such as a plasma display device, a liquid crystal display device, and a projection display device, and a light guide plate of a liquid crystal display.

  Moreover, it can utilize for the use of a transparent conductive material by forming transparent conductive films, such as ITO, on at least one surface on the acrylic resin board of this invention. For example, electric component circuit materials such as capacitors and resistors, copying materials such as electrophotography and electrostatic recording, transparent electrodes for signal input such as liquid crystal displays, electrochromic displays, electroluminescence displays, touch panels, etc., solar cells It can be used for various applications such as a photoelectric conversion element such as an optical amplifier, an antistatic member, an electromagnetic wave shielding member, a surface heating element, and a sensor.

  Hereinafter, the present invention will be described more specifically with reference to examples. In the following description, “parts” and “%” are based on mass. Each evaluation in the table was performed according to the following method.

(1) Weight average molecular weight (Mw):
In order to evaluate the weight average molecular weight of the (co) polymer, 0.05 g of the (co) polymer was dissolved in 10 ml of chloroform (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) and measured under the following conditions. It was.

Apparatus: Liquid chromatography LC-10A type manufactured by Shimadzu Corporation Separation column: 2 KF-806L manufactured by Showa Denko KK Solvent: Chloroform (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.)
Flow rate 1.0ml / min
Detector: Differential refractometer RID-6A manufactured by Shimadzu Corporation
Measurement temperature: 40 ° C
Sample injection volume: 0.1 ml
Standard polymer: Polystyrene.

(2) Deflection temperature under load:
In order to evaluate the heat resistance of the acrylic resin plate, the deflection temperature under load was measured according to the measurement method shown in JIS-K7207.

(3) Haze:
In order to evaluate the optical characteristics of the acrylic resin plate, haze was measured in accordance with the measurement method shown in JIS-K7136.

(4) Water absorption rate:
In order to evaluate the water absorption of the acrylic resin plate, the water absorption was measured as follows. First, the acrylic resin plate was cut into 50 × 50 mm, and the mass a (g) after the sample was dried in a heating furnace at 70 ° C. for 5 days was measured. Next, after dipping in water at 23 ° C. for 20 days and taking out, the sample surface is wiped lightly, and the mass b (g) is measured.
Water absorption (%) = (b−a) / a × 100
As a result, the water absorption was determined.

[Production Example 1]
A monomer mixture consisting of 70 parts of aqueous potassium hydroxide (potassium hydroxide content: 17.1%) and 30 parts of methyl methacrylate was added to a polymerization apparatus equipped with a stirrer and stirred. The temperature was raised to 80 ° C. after the saponification peak was expressed, and the mixture was stirred and held at 85 ° C. for 4 hours after the polymerization peak to obtain an anionic polymer compound aqueous solution (A1). In this heating process, after the temperature reached 70 ° C., 0.05 part of ammonium persulfate was added as a polymerization initiator. Moreover, in order to collect | recover anion type | system | group high molecular weight compound aqueous solution to another container, it diluted with 1000 parts deionized water, and collect | recovered the anionic high molecular weight compound aqueous solution to another container.

[Production Example 2]
In a polymerization apparatus equipped with a stirrer, a monomer mixture consisting of 58 parts of sodium 2-sulfoethyl methacrylate, 31 parts of aqueous potassium methacrylate (potassium methacrylate 30%), 11 parts of methyl methacrylate, and deionized water 900 And the mixture was stirred and dissolved. Thereafter, the mixture was heated to 60 ° C. with stirring in a nitrogen atmosphere, and kept at 60 ° C. with stirring for 6 hours to obtain an aqueous anionic polymer compound solution (A2). In this temperature raising process, after the temperature reached 50 ° C., 0.1 part of ammonium persulfate was added as a polymerization initiator, and 11 parts of methyl methacrylate separately measured was added to the above reaction system over 75 minutes. It was dripped continuously.

[Production Example 3]
A reaction vessel equipped with a stirrer, tricyclo [5,2,1,0 ^2,6] dec-8-yl methacrylate 100 parts, as a polymerization initiator 1,1,3,3-tetramethylbutyl peroxy-2 0.1 part of ethyl hexanoate and 0.05 part of t-dodecyl mercaptan as a chain transfer agent were added and stirred to dissolve. Also, 200 parts of deionized water was put in another container, and 0.1 part of the anionic polymer compound aqueous solution (A1) obtained in Production Example 1 as a dispersion stabilizer and the anionic polymer compound aqueous solution obtained in Production Example 2 were used. (A2) 0.36 part and 0.3 part of sodium sulfate as a dispersion stabilizing aid were added and stirred for dissolution. Next, the monomer mixture in which the initiator and the like were dissolved and the deionized water mixture in which the dispersion stabilizer and the like were dissolved were put into a reaction vessel equipped with a stirrer and stirred at 200 rpm for 15 minutes while purging with nitrogen. Thereafter, the nitrogen substitution was stopped, and the polymerization was started by heating to 70 ° C. while stirring at 300 rpm. After the polymerization peak was exhibited, a heat treatment was performed at 95 ° C. for 30 minutes to complete the polymerization. The obtained bead polymer was filtered, washed with water, and dried at 75 ° C. for 24 hours to obtain a bead polymer having a weight average molecular weight of 1,000,000.

[Production Example 4]
A bead polymer having a weight average molecular weight of 400,000 was obtained in the same manner as in Production Example 3 except that 0.05 part of octyl mercaptan was used instead of 0.05 part of t-dodecyl mercaptan as the chain transfer agent. It was.

[Production Example 5]
Tricyclo [5,2,1,0 ^2,6] in place of dec-8-yl methacrylate, 100 parts of tricyclo [5,2,1,0 ^2,6] dec-8-yl methacrylate 90 parts methyl methacrylate A bead polymer having a weight average molecular weight of 400,000 was obtained in the same manner as in Production Example 3, except that 10 parts were used.

[Production Example 6]
To a reactor equipped with a condenser, a thermometer and a stirrer, 100 parts of methyl methacrylate was supplied and heated with stirring. When the internal temperature reached 80 ° C., 2,2′-azobis- (2, 0.05 part of 4-dimethylvaleronitrile) was added and further heated until the internal temperature reached 90 ° C., and the temperature was maintained for 8 minutes. Thereafter, the mixture was cooled to room temperature to obtain a mixture of a methyl methacrylate polymer and a methyl methacrylate having a polymerization rate of 20% and a weight average molecular weight of 250,000.

[Production Example 7]
To a reactor equipped with a condenser, a thermometer and a stirrer, 100 parts of methyl methacrylate was supplied and heated with stirring. When the internal temperature reached 80 ° C., 2,2′-azobisisobutyro 0.0022 part of nitrile was added and further heated until the internal temperature reached 90 ° C., and the temperature was maintained for 30 minutes. Thereafter, the mixture was cooled to room temperature to obtain a mixture of a methyl methacrylate polymer having a polymerization rate of 7% and a weight average molecular weight of 800,000 and methyl methacrylate.

[Example 1]
15 parts of methyl methacrylate, bis (oxymethyl) tricyclo [5,2,1,0 ^2,6] decane dimethacrylate 80 parts, stirred and dissolved bead-like polymer 5 parts obtained in Production Example 3, acrylic A syrup composition was obtained. Further, to this syrup composition, 0.05 parts of t-hexylperoxypivalate as a polymerization initiator, 0.01 parts of 2,2′-azobisisobutyronitrile, and 0.0 part of t-hexylperoxyisopropyl monocarbonate. 02 parts and 0.03 part of terpinolene as a polymerization regulator were mixed, charged into a suction bottle, stirred and dissolved, and vacuum degassed to obtain a polymerizable mixture.

  This polymerizable mixture was poured into a mold constituted by sandwiching a gasket between a pair of tempered glass sheets having a distance of 1.7 mm, air bubbles were removed, and the mixture was placed in a water bath for 60 minutes at 135 ° C. in a water bath at 80 ° C. Polymerization was carried out for 60 minutes in an air furnace. After cooling, it was peeled from the mold to obtain an acrylic resin plate having a thickness of 1 mm.

  This acrylic resin plate was excellent in heat resistance, transparency and low water absorption. Table 1 shows the raw material composition of the syrup composition of this example and the evaluation results of the acrylic resin plate.

[Examples 2, 3, 6 and Comparative Example 1]
An acrylic resin plate was produced in the same manner as in Example 1 except that the raw material composition of the syrup composition shown in Table 1 and Table 2 was adopted. The evaluation results are shown in Tables 1 and 2.

[Examples 4, 5, and 7, Comparative Example 2]
Example 1 except that the bead polymer obtained in Production Example 4 was used instead of the bead polymer obtained in Production Example 3, and the raw material composition of the syrup composition shown in Table 1 and Table 2 was adopted. An acrylic resin plate was produced in the same manner. The evaluation results are shown in Tables 1 and 2.

[Example 8]
The same procedure as in Example 1 was conducted except that the bead polymer obtained in Production Example 5 was used instead of the bead polymer obtained in Production Example 3 and the raw material composition of the syrup composition shown in Table 1 was adopted. An acrylic resin plate was produced. The evaluation results are shown in Table 1.

[Comparative Example 3]
To a mixture of 20 parts of methyl methacrylate polymer and methyl methacrylate obtained in Production Example 6, bis mixed (oxymethyl) tricyclo [5,2,1,0 ^2,6] decane dimethacrylate 80 parts syrup An acrylic resin plate was produced in the same manner as in Example 1 except that the composition was produced and used. The evaluation results are shown in Table 2.

[Comparative Example 4]
A syrup composition was prepared by mixing 50 parts of neopentylglycol dimethacrylate with 50 parts of the mixture of the methyl methacrylate polymer and methyl methacrylate obtained in Production Example 7, and this example was used except that this was used. In the same manner as in Example 1, an acrylic resin plate was produced. The evaluation results are shown in Table 2.

[Comparative Example 5]
To 100 parts of the mixture of the methyl methacrylate polymer and methyl methacrylate obtained in Production Example 6, 0.05 part of 2,2′-azobis- (2,4-dimethylvaleronitrile) was mixed as a polymerization initiator, The mixture was charged into a suction bottle, stirred and dissolved, and vacuum degassed to obtain a polymerizable mixture.

  This polymerizable mixture was poured into a mold constituted by sandwiching a gasket between a pair of tempered glass sheets having a distance of 1.7 mm, air bubbles were removed, placed in a water bath, 30 minutes in a water bath at 80 ° C., and 130 ° C. Polymerization was carried out for 30 minutes in an air furnace. After cooling, it was peeled from the mold to obtain an acrylic resin plate having a thickness of 1 mm. The evaluation results are shown in Table 2.

[Comparative Example 6]
An acrylic resin plate was produced in the same manner as in Example 1 except that the bead polymer was not used and the raw material composition shown in Table 2 was adopted. The evaluation results are shown in Table 2.

  As shown in Table 1, in Examples 1 to 8, good results were obtained with respect to heat resistance, transparency and low water absorption of the acrylic resin plate. On the other hand, as shown in Table 2, in Comparative Examples 1 to 5, problems such as a decrease in heat resistance of the acrylic resin plate and deterioration in transparency and low water absorption occurred. Further, in Comparative Example 6, although the evaluation result of the obtained acrylic resin plate was good, inconvenience in handling occurred during polymerization, such as leakage of raw materials from the mold.

Claims (2)

4 to 64% by mass of a monoethylenically unsaturated monomer containing a methacrylic acid alkyl ester having an alkyl group having 1 to 4 carbon atoms, and 35 to 95% by mass of a polyfunctional (meth) acrylate represented by the following general formula (1) % And a (co) polymer 1-30 mass% containing a (meth) acrylate unit represented by the following general formula (2) , wherein the (co) polymer is: The composition which consists of 80-100 mass% of (meth) acrylate units shown by General formula (2), and 0-20 mass% of methacrylic acid alkylester units which have a C1-C4 alkyl group .

(In the formula, R ¹ represents H or CH _3. )

(In the formula, R ² represents H or CH _3. ) 4 to 64% by mass of a monoethylenically unsaturated monomer containing a methacrylic acid alkyl ester having an alkyl group having 1 to 4 carbon atoms, and 35 to 95% by mass of a polyfunctional (meth) acrylate represented by the following general formula (1) % And a (co) polymer 1-30 mass% containing a (meth) acrylate unit represented by the following general formula (2) , wherein the (co) polymer is: A step of polymerizing and curing a composition comprising 80 to 100% by mass of the (meth) acrylate unit represented by the general formula (2) and 0 to 20% by mass of a methacrylic acid alkyl ester unit having an alkyl group having 1 to 4 carbon atoms. The manufacturing method of the acrylic resin board which has.

(In the formula, R ¹ represents H or CH _3. )

(In the formula, R ² represents H or CH _3. )