WO2015122174A1

WO2015122174A1 - Methacrylic resin and molded article

Info

Publication number: WO2015122174A1
Application number: PCT/JP2015/000596
Authority: WO
Inventors: 修二磯井; 正和亀田
Original assignee: 株式会社クラレ
Priority date: 2014-02-14
Filing date: 2015-02-10
Publication date: 2015-08-20
Also published as: JPWO2015122174A1; JP6592364B2

Abstract

The present invention provides a methacrylic resin which can be formed into a curved part having improved dimensional accuracy when the methacrylic resin is subjected to a bending or deep drawing processing to form the curved part. The methacrylic resin according to the present invention is a methacrylic resin which comprises a crosslinked alkyl methacrylate polymer, and has a storage modulus of 1.6 MPa or more at 210ºC, 3.0 MPa or less at 170ºC and 6.0 MPa or less at 140ºC in a rubbery flat area thereof, and has a peak value of tanδ in a viscoelastic property of 1.5 or more.

Description

Methacrylic resin and molded products

The present invention relates to a methacrylic resin and a molded product using the same.

A methacrylic resin is a resin containing an alkyl methacrylate polymer polymerized using at least one monomer containing an alkyl methacrylate such as methyl methacrylate.
Methacrylic resins are excellent in transparency, colorability, moldability, weather resistance, etc., making use of these properties as signboards, decoration materials, lighting covers, automobile parts, glazing materials, etc. in various fields. Widely used.
Furthermore, in recent years, with the expansion of the use of methacrylic resin, it has come to be used in the sanitary field such as a bathtub, a bathroom, and a bathroom, and the kitchen field such as a top plate of a system kitchen.

成形 Molded products used in the sanitary field and kitchen field have many curved parts, unlike signboards that are often composed of flat surfaces. For this reason, methacrylic resins used in these applications are required to have higher moldability that allows easy bending or deep drawing.

Since methacrylic resin is originally a thermoplastic resin, it can be bent by heating, but it is easy to flow and difficult to deep-draw.
By using a cross-linked alkyl methacrylate polymer, molding processability is improved, and deep drawing or the like becomes possible.

In Patent Documents 1 and 2, at least one monomer containing an alkyl methacrylate is polymerized in the presence of a polymerization initiator to obtain a prepolymerized syrup, and the resulting syrup further contains at least one kind of alkyl methacrylate. A method for producing a methacrylic resin in which a monomer, a polymerization initiator, a crosslinking agent and the like are added and polymerized in a mold is disclosed.

As a related technique of the present invention, there is Patent Document 3.
In Patent Document 3,
A crosslinked alkyl methacrylate polymer molded product containing an inorganic filler,
(I) the α dispersion peak temperature of the loss elastic modulus (E ″) in the dynamic viscoelastic properties is 100 ° C. or higher;
(Ii) the peak value of tan δ in the dynamic viscoelastic property is 0.8 or more;
and,
(Iii) The storage elastic modulus in a rubber-like flat region 160 ° C. is 30 MPa or less;
There is disclosed a crosslinked alkyl methacrylate-based polymer molded article characterized by having the following characteristics (i) to (iii): (Claim 1)

Japanese Patent Laid-Open No. 10-237260 Japanese Patent Laid-Open No. 10-237132 Japanese Patent Laid-Open No. 9-302100

When a curved portion is formed by performing a bending process or a deep drawing process using a methacrylic resin containing a cross-linked alkyl methacrylate polymer obtained by a conventional manufacturing method, thickness unevenness may occur in the curved part. It is preferable that bending or deep drawing can be performed with higher dimensional accuracy.

The present invention has been made in view of the above circumstances, and a methacrylic resin capable of increasing the dimensional accuracy of a bending portion obtained when a bending portion or deep drawing is performed to form the bending portion. It is intended to provide.
In addition, although the methacrylic resin of the present invention is suitably used when a bending process or a deep drawing process is performed to form a curved portion, it can be used for any application.

The methacrylic resin of the present invention is
A methacrylic resin containing a cross-linked alkyl methacrylate polymer,
The storage elastic modulus in the rubber-like flat region is 1.6 MPa or higher at 210 ° C., 3.0 MPa or lower at 170 ° C., and 6.0 MPa or lower at 140 ° C.,
And,
The peak value of tan δ in the dynamic viscoelastic property is 1.5 or more,
Methacrylic resin.

[Method for measuring storage elastic modulus in rubbery flat region]
In the present invention, the storage elastic modulus of a methacrylic resin in a rubber-like flat region is measured by a dynamic thermomechanical property analysis method (DMTA method). That is, applying a sinusoidal stress to the sample in a mode such as bending, shearing, or tension (tensile mode in the present invention), measuring the storage modulus of the sample as a function of temperature, The storage elastic modulus at 170 ° C., 200 ° C., and 210 ° C. is determined. Here, the storage elastic modulus is an elastic response and corresponds to energy that can be completely recovered.
For specific measurement examples, see the section “Examples” below.

[Method of measuring tan δ peak value and peak temperature]
In the present invention, the tan δ peak value and peak temperature of the methacrylic resin are measured by a dynamic thermomechanical property analysis method (DMTA method). That is, a sinusoidal stress is applied to a sample in a mode such as bending, shearing, or tension (in the present invention, a tensile mode), and the loss tangent of the sample, that is, tan δ, is measured as a function of temperature. Find the temperature. Here, tan δ is a dimensionless number and is equal to the ratio of the loss elastic modulus to the storage elastic modulus per cycle.
For specific measurement examples, see the section “Examples” below.

The molded product of the present invention is a molded product made of the above methacrylic resin of the present invention.
The molded product of the present invention includes a primary molded product such as a resin plate, and a secondary molded product molded using the primary molded product.

According to the present invention, it is possible to provide a methacrylic resin capable of increasing the dimensional accuracy of the obtained bending portion when the bending portion is formed by performing bending or deep drawing.

2 is a graph (DMTA curve) showing the relationship between temperature and storage elastic modulus obtained in Example 1, Comparative Example 1, and Comparative Example 2. 6 is a graph showing the relationship between temperature and tan δ obtained in Example 1 and Comparative Example 2.

The present invention relates to a methacrylic resin.
The methacrylic resin is a resin containing at least one alkyl methacrylate polymer obtained by polymerizing at least one monomer containing alkyl methacrylate.
The methacrylic resin of the present invention contains at least one crosslinked alkyl methacrylate polymer.
The methacrylic resin of the present invention preferably contains at least one crosslinked alkyl methacrylate polymer and at least one non-crosslinked linear alkyl methacrylate polymer.

The methacrylic resin of the present invention has the following physical properties.
That is, the storage elastic modulus in the rubber-like flat region is 1.6 MPa or more at 210 ° C., 3.0 MPa or less at 170 ° C., and 6.0 MPa or less at 140 ° C.
Moreover, the peak value of tan δ in the dynamic viscoelastic property is 1.5 or more.

As described in the section “Problems to be Solved by the Invention”, bending or deep drawing using a methacrylic resin containing a cross-linked alkyl methacrylate polymer obtained by a conventional manufacturing method is performed and curved. When the portion is formed, thickness unevenness may occur in the curved portion.
It is considered that the thickness unevenness is greatly affected by the storage elastic modulus unevenness due to the resin temperature unevenness during the molding process.
A dynamic thermomechanical property analysis method (DMTA method) yields a DMTA curve showing the relationship between temperature and storage modulus (see FIG. 1).
In the DMTA curve, when the glass transition point Tg is exceeded, the storage elastic modulus greatly decreases, but thereafter, a rubber-like flat region where the storage elastic modulus does not change greatly even when the temperature is raised appears. In the rubber-like flat region, the polymer molecular chain moves but does not melt completely. Thereafter, when the temperature is further raised and the flow region is entered, the storage elastic modulus is greatly lowered.
In the methacrylic resin, the molding process is performed within the temperature of the rubber-like flat region. In a methacrylic resin, for example, it is heated to a relatively high temperature within the temperature of the rubber-like flat region, and molding is performed within a temperature between this heating temperature and the lower limit temperature of the rubber-like flat region.
Even if there is uneven temperature of the resin during processing and molding, if the temperature range of the rubber-like flat region is wide, there will be little unevenness of storage elastic modulus, small thickness unevenness in the stretched part, and forming a curved part with high dimensional accuracy. Can do.

140 ° C. is the reference temperature on the low temperature side of the rubber-like flat region, 210 ° C. is the reference temperature on the high temperature side of the rubber-like flat region, and 170 ° C. is the reference temperature of the intermediate region of the rubber-like flat region. It is preferable that the difference in storage elastic modulus at these three reference temperatures is small.

In the methacrylic resin of the present invention, the storage elastic modulus in a rubber-like flat region is 1.6 MPa or more at 210 ° C., 3.0 MPa or less at 170 ° C., and 6.0 MPa or less at 140 ° C.
When the storage elastic modulus at 140 ° C. exceeds 6.0 MPa, the storage elastic modulus on the low temperature side of the rubber-like flat region is higher than the preferred range, and when there is temperature unevenness during molding, the thickness of the low temperature portion is from the desired thickness. There is a risk of shifting.
Since the difference in storage elastic modulus at the three reference temperatures is smaller, the thickness unevenness is smaller, and a curved portion with higher dimensional accuracy can be formed, the storage elastic modulus at 140 ° C. is 4.3 MPa or less. Is preferred.
When the storage elastic modulus at 210 ° C. is less than 1.6 MPa, the storage elastic modulus on the high temperature side of the rubber-like flat region is lower than the preferred range, and when there is temperature unevenness during molding, the thickness of the high temperature portion is from the desired thickness. There is a risk of shifting.
The storage elastic modulus at 210 ° C. is 1.65 MPa or more because the difference in storage elastic modulus at the three reference temperatures is smaller, the thickness unevenness is smaller, and a curved portion with higher dimensional accuracy can be formed. Is preferred.
Since the molding processability of the methacrylic resin is good, the storage elastic modulus at 170 ° C. is preferably 3.0 MPa or less, and more preferably 2.5 MPa or less.

The storage elastic modulus at each temperature of the rubber-like flat region can be adjusted to a preferable range by appropriately selecting the type and blending amount of raw materials used for the production of the methacrylic resin.
For example, the storage elastic modulus at each temperature of the rubber-like flat region can be adjusted by appropriately selecting the type and amount of the monomer and crosslinking agent used.
More specifically, the storage elastic modulus at each temperature of the rubber-like flat region is adjusted by the mass average molecular weight (MW) and blending amount of the linear alkyl methacrylate polymer and the kind and blending amount of the crosslinking agent. can do.

In the present invention, since the processability of the methacrylic resin is improved, the peak value of tan δ in the dynamic viscoelastic property is 1.5 or more. More preferably, it is 1.55 or more. If the peak value of tan δ in the dynamic viscoelastic properties is less than 1.5, the ratio of the viscosity term of the obtained methacrylic resin is too low, and it is not suitable for thermoforming such as bending.

The peak value of tan δ in the dynamic viscoelastic properties is preferably 1.8 or less because the molding processability of the methacrylic resin becomes good. When the peak value of tan δ in the dynamic viscoelastic characteristics is more than 1.8, there is a possibility that a poor appearance due to thickness unevenness in the stretched part may occur in a molding process such as a bending process.

The tan δ peak temperature in the dynamic viscoelastic property is preferably 100 ° C. or higher, more preferably 120 ° C. or higher, and preferably 130 ° C. or lower because the molding processability of the methacrylic resin is improved.

The tan δ peak value of the methacrylic resin tends to increase as the proportion of the linear polymer portion in the resin increases and as the crosslink density in the resin decreases. By adjusting the amount of the linear alkyl methacrylate polymer and the crosslinking agent in the resin, the tan δ peak value and peak temperature of the methacrylic resin can be adjusted within a preferred range.
More specifically, the peak value and peak value of tan δ are adjusted within a preferred range depending on the mass average molecular weight (MW) and blending amount of the linear alkyl methacrylate polymer and the type and blending amount of the crosslinking agent. be able to.

The method for producing the methacrylic resin of the present invention is not particularly limited.
Alkyl methacrylate is added to prepolymerized syrup or dissolved syrup (S) containing at least one non-crosslinked linear alkyl methacrylate polymer (P) and at least one monomer (M1) containing alkyl methacrylate. A method in which at least one monomer (M2) is added and polymerization and crosslinking are performed is preferred.
In this method, prepolymerized syrup or dissolved syrup (S), at least one monomer (M2) comprising an alkyl methacrylate, at least one polymerization initiator (A), at least one crosslinking agent (B), In addition, if necessary, at least one optional additive is blended to prepare a liquid raw material mixture, the liquid raw material mixture is poured into a mold, a polymerization reaction is performed, and a primary molded product such as a resin plate is formed. A methacrylic resin can be produced.

The prepolymerized syrup is obtained by prepolymerizing at least one monomer (M1) containing an alkyl methacrylate in the presence of a polymerization initiator, and is obtained from an uncrosslinked linear alkyl methacrylate polymer (P) and an unpolymerized syrup. And the monomer (M1) of the reaction.
The dissolved syrup is obtained by converting a non-crosslinked linear alkyl methacrylate polymer (P) polymerized using at least one monomer containing alkyl methacrylate into at least one monomer (M1) containing alkyl methacrylate. ).

The non-crosslinked linear alkyl methacrylate polymer (P) may be a homopolymer or copolymer of at least one alkyl methacrylate, or at least one other alkyl methacrylate and at least one other copolymerizable copolymer. A copolymer with an unsaturated monomer may be used.

The alkyl methacrylate used as a raw material for the non-crosslinked linear alkyl methacrylate polymer (P) is preferably an alkyl ester of 1 to 20 carbon atoms of methacrylic acid, and an alkyl ester of 1 to 12 carbon atoms of methacrylic acid. More preferred.
Examples of the alkyl methacrylate include methyl methacrylate (MMA), ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, and cyclohexyl methacrylate.
It is preferable to use at least methyl methacrylate (MMA) as a raw material for the non-crosslinked linear alkyl methacrylate polymer (P).

As a raw material of the non-crosslinked linear alkyl methacrylate polymer (P), as other copolymerizable unsaturated monomers that can be used in combination with alkyl methacrylate,
Alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, and cyclohexyl acrylate;
Hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 2-hydroxy-3-chloropropyl (meth) acrylate;
(Meth) acrylic acid;
(Meth) acrylic acid metal salts;
Vinyl monomers such as vinyl chloride, vinyl acetate, and vinyl toluene;
Acrylonitonyl;
Acrylamide;
Styrenic monomers such as styrene and α-methylstyrene;
and,
And maleic anhydride.

The polymerization rate in the prepolymerized syrup is not particularly limited, preferably 5 to 40%, more preferably 5 to 30%.
If the polymerization rate is less than 5%, the peak value of tan δ is lowered, and there is a possibility that bending or deep drawing with a desired high dimensional accuracy may be difficult.
Here, the “polymerization rate” is the ratio of the amount (mass) of the monomer used in the polymerization reaction to the amount (mass) of the charged monomer.
The concentration of the non-crosslinked linear alkyl methacrylate polymer (P) in the prepolymerized syrup or dissolved syrup (S) is not particularly limited, and is preferably 5 to 40% by mass, and 5 to 30% by mass. More preferably.
The mass average molecular weight (MW) of the non-crosslinked linear alkyl methacrylate polymer (P) in the prepolymerized syrup or dissolved syrup (S) is not particularly limited, but is preferably 100,000 to 1,500,000, preferably 700,000 to 120. Ten thousand is more preferable.
When the mass average molecular weight (MW) is less than 100,000, durability such as chemical resistance may be lowered.

Instead of the prepolymerized syrup or dissolved syrup (S), a partially crosslinked alkyl methacrylate-based gel polymer can also be used.
For the partially crosslinked alkyl methacrylate-based gel polymer, refer to Patent Document 3 listed in the “Background Art” section.

As the monomer (M2), at least one alkyl methacrylate can be used. As the monomer (M2), at least one alkyl methacrylate and another copolymerizable unsaturated monomer can be used in combination.

Examples of the alkyl methacrylate used as the monomer (M2) include methyl methacrylate (MMA), ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, 2-ethylhexyl methacrylate, and lauryl methacrylate. And cyclohexyl methacrylate.
It is preferable to use at least methyl methacrylate (MMA) as the monomer (M2).

As the monomer (M2), other copolymerizable unsaturated monomers that can be used in combination with alkyl methacrylate,
Alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, and cyclohexyl acrylate;
Hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 2-hydroxy-3-chloropropyl (meth) acrylate;
(Meth) acrylic acid;
(Meth) acrylic acid metal salts;
Vinyl monomers such as vinyl chloride, vinyl acetate, and vinyl toluene;
Acrylonitonyl;
Acrylamide;
Styrenic monomers such as styrene and α-methylstyrene;
and,
And maleic anhydride.

The polymerization initiator (A) is not particularly limited.
For example, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), acetylcyclohexylsulfonyl peroxide, isobutyryl peroxide, Cumyl peroxyneodecanoate, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, dimyristyl peroxycarbonate, di- (2-ethoxyethyl) peroxydicarbonate, di- (methoxyisopropyl) per Examples thereof include oxydicarbonate and di- (2-ethylhexyl) peroxydicarbonate.

The crosslinking agent (B) is not particularly limited, and a monomer having at least two (meth) acryloyl groups in the molecule is preferably used.
For example,
Ethylene glycol di (meth) acrylate, 1,3-propylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate (1,3-butanediol di (meth) acrylate), 1,4-butylene Glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate,
Diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate,
Dimethylolethane di (meth) acrylate, 1,1-dimethylolpropane di (meth) acrylate, 2,2-dimethylolpropane di (meth) acrylate,
Trimethylolethane tri (meth) acrylate, trimethylolpropane tri (meth) acrylate,
Tetramethylol methane tri (meth) acrylate, tetramethylol methane di (meth) acrylate,
Tetraethylene glycol di (meth) acrylate,
2,2-bis [4-((meth) acryloxyethoxy) phenyl] propane, 2,2-bis [4-((meth) acryloxypentenoxy) phenyl] propane,
1,4-bis ((meth) acryloyloxymethyl) cyclohexyl di (meth) acrylate,
And polyethylene glycol di (meth) acrylate represented by the following general formula (X).

In the above formula (X), n is an integer of 4 or more, preferably 4 to 14.

In the case of a di (meth) acrylate-based cross-linking agent, the greater the number of carbons between the di (meth) acrylates, the softer the resulting resin tends to be and the lower the storage elastic modulus in the rubbery flat region. .
The temperature range of the rubber-like flat region in the DMTA curve can be adjusted by appropriately selecting the type and amount of the crosslinking agent.
Among the above crosslinking agents, 1,3-butane has a wide temperature range in the rubber-like flat region, and a methacrylic resin having a small difference in storage elastic modulus at 140 ° C., 170 ° C. and 210 ° C. is easily obtained. Diol di (meth) acrylate, neopentyl glycol dimethacrylate, and polyethylene glycol di (meth) acrylate represented by the above formula (X) are preferable.

If necessary, a chain transfer agent (C) and / or an ultraviolet absorber (D) can be used as an additive. These can be used alone or in combination of two or more.

The chain transfer agent (C) is not particularly limited. For example,
Styrene dimers such as α-methyl-styrene dimer;
mercaptans such as n-octyl mercaptan, n-dodecyl mercaptan, and hyophenol;
Thioglycolic acid or esters thereof such as thioglycolic acid, ethyl thioglycolate, and butyl thioglycolate;
β-mercaptopropionic acid, methyl β-mercaptopropionate, β-mercaptopropionic acid such as octyl β-mercaptopropionate, and esters thereof.
As the chain transfer agent (C), styrene dimers such as α-methyl-styrene dimer are preferable.
When a styrene dimer such as α-methyl-styrene dimer is used as the chain transfer agent (C), the greater the amount used, the softer the resin obtained, and the value of the storage elastic modulus in the rubbery flat region Tend to be lower.

The ultraviolet absorber (D) is not particularly limited, and examples thereof include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole.

If necessary, one or more other additives can be used.
Other additives are not particularly limited, other types of resins, antioxidants, colorants such as pigments and dyes, dispersants, fillers, pattern materials such as resin granules and natural stone granules, plasticizers, and the like A mold release agent or the like can be added within a range not impairing the object of the present invention.

The mixing ratio of the raw materials is not particularly limited.
Let the total amount of raw materials other than a polymerization initiator (A) and a ultraviolet absorber (D) be 100 mass parts.
The amount of prepolymerized syrup or dissolved syrup (S) is preferably 30 to 98 parts by mass, and more preferably 50 to 95 parts by mass.
The amount of monomer (M2) (total amount in the case of plural types) is preferably 2 to 70 parts by mass, and more preferably 5 to 50 parts by mass.
The amount of the crosslinking agent (B) (the total amount in the case of plural kinds) is preferably 0.01 to 1.5 parts by mass, more preferably 0.3 to 0.8 parts by mass. If the amount of the cross-linking agent (B) exceeds 1.5 parts by mass, the peak value of tan δ may be lowered, and it may be difficult to perform bending processing or deep drawing processing with a desired high dimensional accuracy.
The amount of the chain transfer agent (C) (the total amount in the case of a plurality of types) is 0 to 1 kg per 1 kg of the total amount of raw materials other than the polymerization initiator (A), the chain transfer agent (C), and the ultraviolet absorber (D). 2.0 g is preferable, and 0 to 0.5 g is more preferable. When the amount of the chain transfer agent (C) exceeds 2.0 g, the durability such as chemical resistance of the methacrylic resin plate obtained by primary molding may be lowered.
The amount of the polymerization initiator (A) (the total amount in the case of plural types) is 0.00 per kg of the total amount of raw materials other than the polymerization initiator (A), the chain transfer agent (C), and the ultraviolet absorber (D). The range of 05 to 3.0 g is preferable, and it is more preferable that the amount be adjusted within the optimum range in accordance with the blending ratio of the raw materials.
The amount of the ultraviolet absorber (D) (the total amount in the case of plural types) is 0 to 1 per kg of the total amount of raw materials other than the polymerization initiator (A), the chain transfer agent (C), and the ultraviolet absorber (D). 2.0 g is preferable, and 0 to 1.0 g is more preferable. If the amount of the ultraviolet absorber (D) exceeds 2.0 g, the methacrylic resin plate may be colored.

The concentration of the crosslinked alkyl methacrylate polymer in the methacrylic resin is preferably 60 to 95% by mass, and more preferably 75 to 95% by mass.
The concentration of the non-crosslinked linear alkyl methacrylate polymer (P) in the methacrylic resin is preferably 5 to 40% by mass, and more preferably 5 to 25% by mass.
Further, the mass average molecular weight (MW) of the non-crosslinked linear alkyl methacrylate polymer (P) is preferably 100,000 to 1,500,000, more preferably 700,000 to 1,200,000. When the mass average molecular weight (MW) is less than 100,000, durability such as chemical resistance may be lowered.

The method for measuring the concentration of the cross-linked alkyl methacrylate polymer is as follows. A sample is taken from the methacrylic resin and crushed to a particle size of 2 to 3 mm, and the crushed sample is weighed on a balance having an accuracy of 0.1 mg. Thereafter, the crushed sample is put into a cylindrical filter paper, and a solute is extracted with chloroform as a solvent by a Soxhlet extractor. The cylindrical filter paper containing the extraction residue is vacuum-dried for 48 hours, and the mass of the insoluble matter is measured with a balance. Thereby, the density | concentration of a bridge | crosslinking alkylmethacrylate polymer can be calculated.
Further, the non-crosslinked linear alkyl methacrylate polymer (P) can be extracted by the same method, and the concentration and mass average molecular weight (MW) can be measured.

"Molding"
The molded product of the present invention comprises the methacrylic resin of the present invention.
The molded product of the present invention includes a primary molded product such as a resin plate, and a secondary molded product molded using the primary molded product.
Using the primary molded product made of the methacrylic resin of the present invention, a secondary molded product having a curved portion can be obtained by performing bending or deep drawing.
By using the methacrylic resin of the present invention, it is possible to obtain a secondary molded product having a small thickness unevenness of the curved portion and high dimensional accuracy. This secondary molded product can be preferably used in the sanitary field such as a bathtub, a bathroom, and a bathroom, and the kitchen field such as a top plate of a system kitchen.
The primary molded product and the secondary molded product can be produced by a known method.

It does not specifically limit as a casting_mold | template used for primary shaping | molding.
For example, a mold composed of a pair of plate-like bodies such as tempered glass, a chrome-plated plate, or a stainless plate and a soft vinyl chloride gasket,
Examples include a mold formed of a pair of endless belts that travel in the same direction and at the same speed, and a gasket that travels at the same speed as both endless belts on opposite sides of the pair of endless belts.
When a resin plate is produced as a primary molded product, the thickness is generally preferably in the range of 1 to 10 mm depending on the intended use.

As described above, according to the present invention, a methacrylic resin capable of increasing the dimensional accuracy of the bending portion obtained when the bending portion is formed by performing bending processing or deep drawing processing, and the like. A molded article using can be provided.
In addition, although the methacrylic resin of the present invention is suitably used when a bending process or a deep drawing process is performed to form a curved portion, it can be used for any application.

Examples and comparative examples according to the present invention will be described.

Measurement methods in Examples and Comparative Examples are as follows.
(1) Measurement of mass average molecular weight (MW):
A 5 g sample was extracted with 200 ml of chloroform, filtered to collect the filtrate, and methanol was added to form a precipitate. The precipitate was vacuum-dried, and then 0.12 g thereof was dissolved in 20 ml of tetrahydrofuran to obtain a measurement sample. “LC-9A” manufactured by Shimadzu Corporation is used as a molecular weight measuring device, “GPC-802”, “HSG-30” and “HSG-50” manufactured by Shimadzu Corporation and “Shedex A-806” manufactured by Showa Denko KK Was used to measure the molecular weight by GPC.

(2) Evaluation of dynamic viscoelastic properties:
This was carried out in accordance with JIS K7244-1 and JIS 7244-4.
First, a resin plate (length 1250 mm, width 2500 mm, thickness 3 mm) was cut to obtain a sample 20 mm long, 1.5 mm wide, and 2 mm thick.
Measurement was carried out using a dynamic viscoelasticity measuring apparatus (“Rheogel-E4000” manufactured by UBM).
A sinusoidal vibration having a set frequency and amplitude was applied to the sample at elevated temperature, the stress response generated at that time was detected, and the phase difference between the dynamic stress waveform and the dynamic displacement waveform was obtained. Each data such as storage elastic modulus, loss elastic modulus, and tan δ was plotted with respect to the temperature in the measurement region by an arithmetic expression based on the linear viscoelasticity theory to obtain a DMTA curve or the like. The main measurement conditions were set as follows. From this, the storage elastic modulus in 140 degreeC, 170 degreeC, 200 degreeC, and 210 degreeC of the rubber-like flat area | region was calculated | required. Further, the peak value and peak temperature of tan δ were determined.
<Measurement conditions>
Measurement frequency: 1Hz
Load: 1kg
Measurement mode: Temperature dependence Measurement temperature: 30-250 ° C
Temperature rising condition: 3 ° C / min

"Preparation of pre-polymerized syrup"
2,2′-Azobisisobutyronitrile as a polymerization initiator is added to methyl methacrylate (MMA) and heated with stirring, so that the weight average molecular weight (MW) of the linear methyl methacrylate (MMA) polymer is about Polymerization was carried out until reaching 800,000. Thereafter, the mixture was cooled and further diluted with MMA to prepare a prepolymerized syrup having a viscosity of 10 poise.
The viscosity was measured with a B-type viscometer (NDJ-5S rotational viscometer, rotation speed: 12 rpm, rotor: L-type No. 2), and the mass average molecular weight (MW) was determined by the method described in (1) above. It was measured.

The following three types of monomers were prepared as the monomer (M2).
Methyl methacrylate (MMA),
Ethylhexyl acrylate,
Butyl acrylate.

The following two materials were prepared as the polymerization initiator (A).
2,2′-azobis (isobutyronitrile),
2,2'-azobis (2,4-dimethylvaleronitrile).

The following four materials were prepared as the crosslinking agent (B).
1,3-butanediol dimethacrylate,
Ethylene glycol dimethacrylate,
Polyethylene glycol dimethacrylate represented by the above general formula (X) and n = 4,
Neopentyl glycol dimethacrylate.

As the chain transfer agent (C), the following one kind of material was prepared.
α-methyl-styrene dimer.

As the ultraviolet absorber (D), the following one material was prepared.
2- (2′-hydroxy-5′-methylphenyl) benzotriazole.

The following 1 type of material was prepared as a pigment.
White pigment (titanium oxide paste).

Table 1 shows the prepolymerized syrup, monomer (M2), polymerization initiator (A), crosslinking agent (B), chain transfer agent (C), ultraviolet absorber (D), and pigment. A liquid raw material mixture having a composition was prepared.
In Table 1, the unit of the blending amount of the raw materials other than the polymerization initiator (A) and the ultraviolet absorber (D) is “part by mass”, and the raw materials other than the polymerization initiator (A) and the ultraviolet absorber (D) The total amount is 100 parts by mass.
The blending amount of the polymerization initiator (A) and the ultraviolet absorber (D) is indicated by the added amount [g] per 1 kg of the total amount of raw materials other than the polymerization initiator (A) and the ultraviolet absorber (D).

The obtained raw material mixture was defoamed, poured into a mold composed of a pair of tempered glass and a soft vinyl chloride gasket, and heated at 60 ° C. for 2 hours for primary curing. Further, it was heated at 120 ° C. for 2 hours to be secondarily cured, cooled to about 60 ° C., and then taken out from the mold to obtain a methacrylic resin plate (primary molded product) having a length of 1250 mm, a width of 2500 mm, and a thickness of 3 mm.

About the resin board obtained in each case, the dynamic viscoelastic property described in the above (2) was evaluated.
As a representative example, FIG. 1 shows a graph (DMTA curve) showing the relationship between the temperature and the storage elastic modulus obtained in the evaluation of dynamic viscoelastic properties for Example 1, Comparative Example 1, and Comparative Example 2.
As a representative example, FIG. 2 shows a graph showing the relationship between the temperature obtained by evaluating the dynamic viscoelastic properties and tan δ for Example 1 and Comparative Example 2. In Comparative Example 1, since the peak value of tan δ was almost the same as that in Example 1, the graph showing the relationship between the temperature and tan δ is omitted.
Table 2 shows the evaluation results of the evaluation of dynamic viscoelastic properties for the resin plates obtained in each example.

A methacrylic resin plate (length 1250 mm, width 2500 mm, thickness 3 mm) obtained in each example was heated to 180 ° C. with a heater of a vacuum forming machine, and then a bowl-shaped mold (external dimension, having an opening on the upper surface) The entire circumference of the resin plate was held with a clamp. After pushing up the mold in this state, using a vacuum pump, the air in the space between the mold and the resin plate is evacuated so that the resin plate follows the inner shape of the bowl-shaped mold, and an opening is formed on the upper surface. Secondary forming into a box shape having. This was cooled to about 70 ° C. using a blower, and the cooled and solidified secondary molded product was removed from the mold.
As described above, a box-shaped secondary molded product having outer dimensions of 775 mm in length, 1350 mm in width, and 530 mm in height was obtained.
Confirm the appearance of the obtained secondary molded product with the naked eye, and based on the following criteria, the appearance state due to thickness unevenness in the bent part and the stretched part connected there, and mold reproducibility (molded product faithful to the mold) Was obtained). The evaluation results are shown in Table 2.
Criteria A (good): mold reproducibility is good and there is no appearance defect due to thickness unevenness.
B (possible): The mold reproducibility is good, but there is a slight appearance defect due to thickness unevenness.
C (defect): The mold reproducibility is poor and there is an appearance defect caused by thickness unevenness.

About the secondary molded product of Example 2 (the above-mentioned evaluation result A), Example 5 (the above-mentioned evaluation result B), and Comparative Example 1 (the above-mentioned evaluation result C), thickness unevenness was evaluated as follows.
One portion was selected from the four corners of the obtained secondary molded product, and the bent portion and the stretched portion were cut to obtain fragments. Of the obtained fragments, 10 locations in the depth direction of the secondary molded product are arbitrarily selected within the region where the appearance defect is seen (the region corresponding to the secondary molded product with good appearance), and the micrometer Was used to measure the thickness of each part. A total of nine values were calculated as the absolute value of the difference in thickness between two measurement points adjacent to each other, and the average value was obtained. The measurement result of the average value of the thickness difference was as follows.
Example 2: 0.018 mm
Example 5: 0.020 mm
Comparative Example 1: 0.022 mm.
From the above results, it was found that in Examples 2 and 5 in which there was no appearance defect or few, the thickness unevenness was small compared to Comparative Example 1 in which the appearance defect was present.

In Examples 1 to 7, the storage elastic modulus in the rubber-like flat region is 1.6 MPa or more at 210 ° C., 3.0 MPa or less at 170 ° C., 6.0 MPa or less at 140 ° C., and tan δ A methacrylic resin plate having a peak value of 1.5 or more could be produced. In these Examples 1 to 7, there was no / or slight appearance defect due to uneven thickness of the bent portion and the stretched portion, and a secondary molded product with high mold reproducibility could be obtained.
In Examples 1 to 4, 6, and 7, a methacrylic resin plate having the above characteristics and having a tan δ peak temperature of 130 ° C. or less in the dynamic viscoelastic characteristics could be produced. In Examples 1 to 4, and 6, there was no appearance defect due to thickness unevenness of the bent portion and the stretched portion, and a secondary molded product with high mold reproducibility could be obtained.
The methacrylic resin plate obtained in Comparative Example 1 had a storage elastic modulus at 210 ° C. in a rubber-like flat region lower than that in Examples 1-7. The methacrylic resin plate obtained in Comparative Example 2 had a storage elastic modulus at 140 ° C. higher than those in Examples 1-7. In Comparative Examples 1 and 2, secondary molded products having poor appearance due to thickness unevenness in the bent portion and the stretched portion, no mold reproducibility, and poor appearance aesthetics were obtained.

This application claims priority based on Japanese Patent Application No. 2014-026435 filed on Feb. 14, 2014, the entire disclosure of which is incorporated herein.

The methacrylic resin of the present invention can be suitably used for molded products used in sanitary fields such as bathtubs, bathrooms, and toilets, and kitchen fields such as the tops of system kitchens.

Claims

A methacrylic resin containing a cross-linked alkyl methacrylate polymer,
The storage elastic modulus in the rubber-like flat region is 1.6 MPa or higher at 210 ° C., 3.0 MPa or lower at 170 ° C., and 6.0 MPa or lower at 140 ° C.,
And,
The peak value of tan δ in the dynamic viscoelastic property is 1.5 or more,
Methacrylic resin.
The methacrylic resin according to claim 1, wherein the peak temperature of tan δ in the dynamic viscoelastic property is 130 ° C or lower.
The methacrylic resin according to claim 1 or 2, wherein a storage elastic modulus in a rubber-like flat region is 4.3 MPa or less at 140 ° C.
The methacrylic resin according to any one of claims 1 to 3, comprising a pigment.
A molded article made of a methacrylic resin according to any one of claims 1 to 4.