JP2019001883A - Acrylic multilayer polymer - Google Patents

Abstract

To provide an acrylic multilayer polymer excellent in transparency, ductility, film production property, pyrolytic resistance, folding resistance, hot water whitening resistance, and stress whitening resistance, and high in hardness, tear strength.SOLUTION: There is provided an acrylic multilayer polymer consisting of an outer layer consisting of a thermoplastic polymer (III), and a crosslinked elastic layer having an intermediate layer consisting of a crosslinked rubber polymer (II) and a crosslinked elastic body layer having an inner layer covered by intermediate layer, and covered in contact with the outer layer, in which a value calculated by Formula:x y z/d is 400 to 1000, where amount of an acetone soluble part contained in the acrylic multilayer polymer is x mass% based on the acrylic multilayer polymer, acetone swelling degree of the acetone insoluble part contained in the acrylic multilayer polymer is y mass%, number average value of a ratio of a longer diameter to a short diameter of a part stained with ruthenium by an electron microscope observation is z, and number average value of a diameter of the part stained with ruthenium by the electron microscope observation is d nanometer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an acrylic multilayer polymer. More specifically, the present invention relates to an acrylic multilayer polymer having excellent transparency, ductility, film-forming property, heat decomposability, folding resistance, hot water whitening resistance, stress whitening resistance, and high hardness and tear strength.

In order to adjust the characteristics of the methacrylic resin, a technique using an acrylic crosslinked rubber polymer or the like is known.
For example, Patent Document 1 discloses that a part of a methacrylic ester copolymer is grafted to acrylate cross-linked elastic particles, and a reduced viscosity of methyl ethyl ketone soluble component is 0.2 to 0.8 dl / g. A methacrylic resin composition is disclosed.

  Patent Document 2 discloses an acrylic graft copolymer obtained by graft-polymerizing a monomer component containing a methacrylic ester to an acrylic ester rubber-like polymer, and a methacrylic polymer containing 80% by mass or more of a methyl methacrylate unit. Disclosed is a resin composition comprising a coalescence and having a reduced viscosity of methyl ethyl ketone solubles of 0.2 to 0.8 dl / g.

  Patent Document 3 discloses that methyl methacrylate is 80 to 99.95% by mass, acrylic acid alkyl ester monomer having an alkyl group having 1 to 8 carbon atoms is 0 to 19.95% by mass, and crosslinkable monomer is 0.05. A core comprising polymer (III) obtained by polymerizing ˜2% by mass, an acrylic acid alkyl ester monomer having an alkyl group having 1 to 8 carbon atoms, and an aromatic vinyl monomer An inner shell containing a crosslinked rubber polymer (I) obtained by polymerizing 1 to 19% by mass of a polymer and 1 to 5% by mass of a crosslinkable monomer, and 80 to 100% by mass of methyl methacrylate and the number of carbon atoms It is a three-layer polymer particle composed of an outer shell containing a thermoplastic polymer (II) obtained by polymerizing 0 to 20% by mass of an acrylic acid alkyl ester monomer having 1 to 8 alkyl groups. Resin containing crosslinked rubber particle component It discloses a Narubutsu.

  In Patent Document 4, a monomer having an alkyl methacrylate ester as a main component is graft-polymerized in the presence of an innermost layer polymer having a structure of one layer or two or more layers obtained by using an alkyl acrylate ester as a main component. A rubber-containing polymer having a multilayer structure of two or more layers having a mass average particle diameter of 0.01 to 0.5 μm formed by molding an outermost layer polymer having a structure of one layer or two or more layers. An acrylic resin composition is disclosed.

  Such blending of an acrylic crosslinked rubber polymer with a methacrylic resin brings about an improvement in ductility, while at the same time causing a decrease in hardness, a decrease in film forming property, and the like.

JP 2003-128734 A JP 2004-137298 A JP, 2006-186081, A JP 2006-143785 A

  An object of the present invention is to provide an acrylic multilayer polymer that is excellent in transparency, ductility, film-forming property, thermal decomposition resistance, folding resistance, hot water whitening resistance, stress whitening resistance, and has high hardness and tear strength. That is.

  In order to achieve the above object, the present invention including the following aspects has been completed.

[1] An acrylic multilayer polymer comprising an outer layer made of a thermoplastic polymer (III) and a crosslinked elastic body layer covered in contact with the outer layer,
The crosslinked elastic body layer has an intermediate layer made of a crosslinked rubber polymer (II) and an inner layer made of the crosslinked polymer (I) and covered in contact with the intermediate layer,
The crosslinked polymer (I) is composed of 40 to 98.95% by mass of structural units derived from methyl methacrylate, 1 to 59.95% by mass of structural units derived from monofunctional monomers other than methyl methacrylate, and polyfunctional. Consisting of 0.05 to 0.4 mass% of structural units derived from monomers,
The crosslinked rubber polymer (II) is derived from a structural unit derived from methyl methacrylate and a structural unit derived from alkyl acrylate having an alkyl group having 1 to 8 carbon atoms and / or a conjugated diene. A structure comprising 80 to 98% by mass of structural units and 1.0 to 1.7% by mass of structural units derived from a polyfunctional monomer, and derived from a polyfunctional monomer in the crosslinked rubber polymer (II) The ratio of the mass of the structural unit derived from the polyfunctional monomer in the crosslinked polymer (I) to the mass of the unit is 0.05 to 0.25,
Thermoplastic polymer (III) is 80 to 100% by mass of structural units derived from methyl methacrylate, and 0 to 20% by mass of structural units derived from an alkyl acrylate ester having an alkyl group having 1 to 8 carbon atoms. Consists of
The amount of the crosslinked polymer (I) is 1 to 30% by mass, the amount of the crosslinked rubber polymer (II) is 20 to 49% by mass, and the amount of the thermoplastic polymer (III) is based on the acrylic multilayer polymer. 50-79% by mass,
The amount of acetone-soluble component contained in the acrylic multilayer polymer is x% by mass with respect to the mass of the acrylic multilayer polymer, and the acetone swelling degree of acetone-insoluble component contained in the acrylic multilayer polymer is y% by mass. Ruthenium observed by an electron microscope in a section obtained by melting a strand obtained by melting an acrylic multilayer polymer at 250 ° C. using a capillograph and flowing out at a shear rate of 1220 sec ^−1. When the number average value of the ratio of the major axis to the minor axis of the stained portion is z, and the number average value of the diameter of the ruthenium stained portion observed by the electron microscope is d nanometer, the formula: x · y -The value calculated by z / d is 400 or more and 1000 or less,
Acrylic multilayer polymer.

[2] The acrylic multilayer polymer according to [1], wherein the acetone-soluble component has a ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn) of 2 to 3.
[3] The acrylic multilayer polymer according to [1] or [2], wherein y is 500 to 650.
[4] The methacrylic multilayer polymer according to any one of [1] to [3], wherein z is 1.3 to 3.0.
[5] The acrylic multilayer polymer according to any one of [1] to [4], wherein x is 48 to 60 and d is 60 to 110.

[6] A film comprising the acrylic multilayer polymer according to any one of [1] to [5].

  The acrylic multilayer polymer of the present invention is excellent in transparency, ductility, film-forming property, thermal decomposition resistance, folding resistance, hot water whitening resistance and stress whitening resistance, and has high hardness and tear strength. The acrylic multilayer polymer of the present invention is suitable as a molding material for electric parts, vehicle parts, optical parts, ornaments, signs, building materials and the like. The film of this invention is excellent in the uniformity of thickness, and is excellent in the lamination property to another member. For example, the film of the present invention does not whiten and is excellent in flexibility even if it is subjected to bending or the like after being laminated with a vinyl chloride film.

  The reason why the acrylic multilayer polymer of the present invention exhibits the above-mentioned effects is not clear, but the crosslinked polymer (I) suppresses deformation of the crosslinked rubber polymer (II) during melt flow and plastic deformation. By doing so, it is presumed that stress whitening in the acrylic multilayer polymer is suppressed. Further, it is presumed that the crosslinked polymer (I) contributes to improvement of melt moldability of the acrylic multilayer polymer by suppressing gelation. It is presumed that controlling the flexibility of the crosslinked polymer (I) by the amount of the polyfunctional monomer contributes to the improvement of the ductility, folding resistance and tear strength of the acrylic multilayer polymer.

It is a figure which shows the electron micrograph of the acrylic type multilayer polymer of this invention.

  Embodiments of the present invention will be described below, but the present invention is not limited to the embodiments.

  The acrylic multilayer polymer of the present invention comprises an outer layer made of a thermoplastic polymer (III) and a crosslinked elastic body layer covered in contact with the outer layer.

  The thermoplastic polymer (III) is a polymer composed of a structural unit derived from methyl methacrylate and a structural unit derived from an alkyl acrylate ester having an alkyl group having 1 to 8 carbon atoms. It is preferable that the thermoplastic polymer (III) does not contain a structural unit derived from a polyfunctional monomer.

  The amount of the structural unit derived from methyl methacrylate constituting the thermoplastic polymer (III) is 80 to 100% by mass, preferably 85 to 97% by mass, based on the mass of the thermoplastic polymer (III). .

  The amount of the structural unit derived from the alkyl acrylate ester having an alkyl group having 1 to 8 carbon atoms constituting the thermoplastic polymer (III) is 0 to 20 mass relative to the mass of the thermoplastic polymer (III). %, Preferably 3 to 15% by mass.

  Examples of the alkyl acrylate ester having an alkyl group having 1 to 8 carbon atoms include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and propyl acrylate.

  The outer layer may be a single layer composed of one kind of thermoplastic polymer (III) or a multilayer composed of two or more kinds of thermoplastic polymers (III).

  The amount of the thermoplastic polymer (III) is 50 to 79% by mass, preferably 54 to 76% by mass, and more preferably 58 to 72% by mass with respect to the mass of the acrylic multilayer polymer.

  The crosslinked elastic body layer has an intermediate layer made of a crosslinked rubber polymer (II) and an inner layer made of the crosslinked polymer (I) and covered with the intermediate layer. In the crosslinked elastic layer, the inner layer and the intermediate layer preferably form a core and a shell.

  Crosslinked polymer (I) consists of a structural unit derived from methyl methacrylate, a structural unit derived from a monofunctional monomer other than methyl methacrylate, and a structural unit derived from a polyfunctional monomer.

  The amount of the structural unit derived from methyl methacrylate constituting the crosslinked polymer (I) is 40 to 98.95% by mass, preferably 45 to 79.9% by mass, based on the mass of the crosslinked polymer (I). It is.

The amount of the structural unit derived from the monofunctional monomer other than methyl methacrylate constituting the crosslinked polymer (I) is 1 to 59.95% by mass with respect to the mass of the crosslinked polymer (I), preferably It is 20-54.9 mass%.
Monofunctional monomers other than methyl methacrylate include methacrylic acid esters other than methyl methacrylate such as ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate; methyl acrylate, ethyl acrylate, butyl acrylate, acrylic acid 2 -Acrylic esters such as ethylhexyl and propyl acrylate; Aromatic vinyl compounds such as styrene, p-methylstyrene and α-methylstyrene; Maleimide compounds such as N-propylmaleimide, N-cyclohexylmaleimide and N-o-chlorophenylmaleimide Can be mentioned.

The amount of the structural unit derived from the polyfunctional monomer constituting the crosslinked polymer (I) is 0.05 to 0.4% by mass, preferably 0.1% with respect to the mass of the crosslinked polymer (I). It is -0.3 mass%.
Polyfunctional monomers include ethylene glycol dimethacrylate, propylene glycol dimethacrylate, triethylene glycol dimethacrylate, hexanediol dimethacrylate, ethylene glycol diacrylate, propylene glycol diacrylate, triethylene glycol diacrylate, allyl methacrylate, triallyl Examples include isocyanurate.

  The inner layer may be a single layer made of one kind of cross-linked polymer (I) or a multi-layer made of two or more kinds of cross-linked polymers (I).

  The amount of the crosslinked polymer (I) is 1 to 30% by mass, preferably 2 to 10% by mass, more preferably 3 to 7% by mass, based on the mass of the acrylic multilayer polymer.

  The inner layer made of the crosslinked polymer (I) has two types in order to control the flexibility of the crosslinked elastic layer and to store a low molecular weight additive such as an ultraviolet absorber. A multilayer composed of the above crosslinked polymer (I) is preferred.

  The crosslinked rubber polymer (II) is a structural unit derived from methyl methacrylate, a structural unit derived from an alkyl acrylate ester having an alkyl group having 1 to 8 carbon atoms, and / or a structural unit derived from a conjugated diene, and Consists of structural units derived from functional monomers.

  The amount of the structural unit derived from methyl methacrylate constituting the crosslinked rubber polymer (II) is 1 to 19% by mass, preferably 1.9 to 10% by mass, based on the mass of the crosslinked rubber polymer (II). It is.

  The amount of the structural unit derived from the alkyl acrylate ester having an alkyl group having 1 to 8 carbon atoms constituting the crosslinked rubber polymer (II) and / or the amount of the structural unit derived from the conjugated diene depends on the amount of the crosslinked rubber polymer (II). 80 to 98% by mass, preferably 88.9 to 97% by mass, based on the mass of

  Examples of the alkyl acrylate ester having an alkyl group having 1 to 8 carbon atoms include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and propyl acrylate.

  Examples of the conjugated diene include 1,3-butadiene and isoprene.

The amount of the structural unit derived from the polyfunctional monomer constituting the crosslinked rubber polymer (II) is from 1 to 1.7% by mass, preferably 1.1, based on the mass of the crosslinked rubber polymer (II). It is -1.6 mass%.
Polyfunctional monomers include ethylene glycol dimethacrylate, propylene glycol dimethacrylate, triethylene glycol dimethacrylate, hexanediol dimethacrylate, ethylene glycol diacrylate, propylene glycol diacrylate, triethylene glycol diacrylate, allyl methacrylate, triallyl Examples include isocyanurate.
From the viewpoint of improving ductility, folding resistance, and tear strength, the polyfunctional monomer in the cross-linked polymer (I) with respect to the mass of the structural unit derived from the polyfunctional monomer in the cross-linked rubber polymer (II) The ratio of the mass of the derived structural unit is 0.05 to 0.25, preferably 0.06 to 0.25, and more preferably 0.08 to 0.20.
The glass transition temperature of the crosslinked rubber polymer (II) is preferably lower than the glass transition temperature of the crosslinked polymer (I).

  The intermediate layer may be a single layer composed of one kind of crosslinked rubber polymer (II), or may be a multilayer composed of two or more kinds of crosslinked rubber polymers (II).

  The amount of the crosslinked rubber polymer (II) is 20 to 49% by mass, preferably 24 to 44% by mass, and more preferably 25 to 39% by mass with respect to the mass of the acrylic multilayer polymer.

The amount of acetone-soluble component contained in the acrylic multilayer polymer is x% by mass with respect to the mass of the acrylic multilayer polymer, and the acetone swelling degree of acetone-insoluble component contained in the acrylic multilayer polymer is y% by mass. Ruthenium observed by an electron microscope in a section obtained by melting a strand obtained by melting an acrylic multilayer polymer at 250 ° C. using a capillograph and flowing out at a shear rate of 1220 sec ^−1. The number average value of the ratio of the major axis to the minor axis of the dyed portion (hereinafter sometimes referred to as aspect ratio) is z, and the number average value of the diameter of the ruthenium-dyed portion observed with an electron microscope (hereinafter referred to as “aspect ratio”) The average diameter) may be d nanometers, the value calculated by the formula: x · y · z / d is 400 or more and 1000 or less, preferably 4 0 to 950 or less, more preferably 500 or more 900 or less. When the value calculated by the formula: x · y · z / d is large, the stress whitening resistance and the hot water whitening resistance tend to decrease. When the value calculated by the formula: x · y · z / d is small, the film forming property, ductility, folding resistance, and tear strength tend to decrease. The amount of the alkali-soluble component, the degree of acetone swelling, the aspect ratio, and the number average value of the particle diameter can be adjusted by the amount of the polyfunctional monomer used, the ratio between the outer layer and the cross-linked elastic layer, and the like.

  From the viewpoint of improving the balance between improvement in ductility, folding resistance and tear strength, and improvement in transparency and stress whitening resistance, the acrylic multilayer polymer preferably has an acetone swelling degree of acetone-insoluble matter contained therein. Is 500-650 mass%, More preferably, it is 510-630 mass%, More preferably, it is 520-600 mass%.

  From the viewpoint of coexistence of improvement in ductility, folding resistance and tear strength, and improvement in film forming property, the amount of acetone-soluble component contained in the acrylic multilayer polymer is relative to the acrylic multilayer polymer. Preferably it is 48-60 mass%, Preferably it is 49-59 mass%, More preferably, it is 49-58 mass%.

  The degree of swelling of acetone and the amount of acetone soluble matter are determined as follows. 2 g (w0) of the acrylic multilayer polymer precisely weighed was added to 100 ml of acetone and stirred at room temperature for 24 hours. The obtained liquid was put into a centrifuge tube and centrifuged at 5 ° C. and 20000 rpm for 120 minutes. The supernatant was then removed by decantation, leaving insolubles at the bottom of the settling tube. Acetone was added to the settling tube and stirred. Centrifugation was performed at 5 ° C. and 20000 rpm for 120 minutes. The supernatant was then removed by decantation. The insoluble matter in the state of absorbing acetone was taken out from the bottom of the settling tube, and its mass w1 was measured. The insoluble matter in a state where acetone was absorbed was dried at 80 ° C. to obtain an insoluble matter containing no acetone, and its mass w2 was measured. The degree of acetone swelling of acetone-insoluble matter was calculated by the formula: 100 × w1 / w2. The amount of acetone soluble matter was calculated by the formula: 100 × (w0−w2) / w0.

The acetone-soluble component can be obtained by removing acetone from the supernatant at 50 ° C. under reduced pressure and drying the solid residue at 80 ° C.
The acetone-soluble component is preferably a ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn), preferably 2 to 3, more preferably, from the viewpoint of achieving both improved film-forming properties and improved warm water whitening resistance. 2.1 to 2.8, more preferably 2.2 to 2.7.
In addition, the acetone-soluble component has a weight average molecular weight of preferably 50,000 to 150,000, more preferably 60,000 to 120,000, from the viewpoint of achieving both improved film-forming properties and improved film strength. More preferably, it is 70,000-100,000.

The aspect ratio is preferably 1.3 to 3.0, more preferably 1.3 to 2.5, and still more preferably 1 from the viewpoints of improving ductility and folding resistance and suppressing anisotropy of tear strength. 4 to 2.2. The aspect ratio in the present application is that an acrylic multilayer polymer is melted at 250 ° C. using a capillograph, and a strand obtained when flowing out at a shear rate of 1220 sec ⁻¹ is cut in the longitudinal direction, and is observed with an electron microscope. It is the number average value of the ratio of the major axis to the minor axis of the ruthenium-stained portion.
Moreover, the number average value (average diameter) of the diameter of the ruthenium-stained portion observed with an electron microscope is preferably 60 to 110 nm, more preferably 65 to 105 nm, and still more preferably 70 to 100 nm.
The crosslinked polymer (I) or the crosslinked rubber polymer (II) is easily dyed with ruthenium. On the other hand, the thermoplastic polymer (III) is hardly dyed by ruthenium. The ruthenium-dyed portion is considered to be a portion where the crosslinked polymer (I) or the crosslinked rubber polymer (II) is exposed by cutting.

The acrylic multilayer polymer is not particularly limited depending on the production method. For example, emulsion polymerization can be exemplified.
In the case of emulsion polymerization, for example, the monomer (i) for constituting the crosslinked polymer (I) is emulsion-polymerized to obtain a latex containing the crosslinked polymer (I), and the crosslinked rubber polymer ( Add monomer (ii) to constitute II) and seed emulsion polymerize monomer (ii) to obtain a latex containing crosslinked polymer (I) and crosslinked rubber polymer (II). Further, a monomer (iii) for constituting the thermoplastic polymer (III) is added thereto, and the monomer (iii) is subjected to seed emulsion polymerization to obtain a latex containing an acrylic multilayer polymer. it can. Emulsion polymerization is a known method used to obtain a latex containing a polymer. Seed emulsion polymerization is a method in which a monomer polymerization reaction is performed on the surface of seed particles. Seed emulsion polymerization is preferably used to obtain core-shell structured polymer particles.

  The polymerization initiator used in emulsion polymerization and seed emulsion polymerization is not particularly limited. Examples of the polymerization initiator include water-soluble inorganic initiators such as potassium persulfate and ammonium persulfate; redox initiators comprising inorganic initiators combined with sulfites or thiosulfates; organic peroxides The redox initiator etc. which combine ferrous salt or sodium sulfoxylate etc. can be mentioned. The polymerization initiator may be added to the reaction system all together at the start of the polymerization, or may be added to the reaction system separately at the start of polymerization and during the polymerization in consideration of the reaction rate.

  The emulsifier used in emulsion polymerization and seed emulsion polymerization is not particularly limited. Examples of the emulsifier include dialkyl sulfosuccinates such as sodium dioctyl sulfosuccinate and sodium dilauryl sulfosuccinate which are anionic emulsifiers, alkyl benzene sulfonates such as sodium dodecylbenzene sulfonate, and alkyl sulfates such as sodium dodecyl sulfate; Polyoxyethylene alkyl ether, polyoxyethylene nonylphenyl ether, etc., which are emulsifiers; polyoxyethylene nonylphenyl ether sulfate, such as sodium polyoxyethylene nonylphenyl ether sulfate, which is a nonionic / anionic emulsifier, polyoxyethylene alkyl ether sulfate Polyoxyethylene alkyl ether sulfates such as sodium, alkyl ethers such as sodium polyoxyethylene tridecyl ether acetate Carboxylic acid salts and the like. The number of moles of the oxyethylene structural unit added in the nonionic emulsifier and the nonionic anionic emulsifier is preferably 30 mol or less, more preferably 20 mol or less, most preferably in order to prevent the foaming property of the emulsifier from becoming extremely large. Is 10 mol or less. These emulsifiers can be used alone or in combination of two or more.

  The usage-amount of a polymerization initiator and an emulsifier can be suitably set so that the average particle diameter (D) of the acryl-type multilayer polymer contained in latex may become a desired range. The amount of the emulsifier used varies depending on the type of the emulsifier. For example, it is preferably 0.5 to 3 parts by mass, more preferably 100 parts by mass relative to the total amount of monomers for producing the acrylic multilayer polymer. Is 1 to 2 parts by mass.

The average particle diameter (D) of the acrylic multilayer polymer contained in the latex is preferably 80 nm or more and 150 nm or less, more preferably 90 nm or more and 120 nm or less. When the particle diameter of the acrylic multilayer polymer is too small, the number average value of the diameter of the ruthenium-stained portion observed with an electron microscope tends to be small. When the particle diameter of the acrylic multilayer polymer is too large, the stress whitening resistance tends to decrease.
The average particle diameter D of the acrylic multilayer polymer contained in the latex can be determined as follows. The latex containing the acrylic multilayer polymer was diluted with ion-exchanged water so as to have a concentration of 0.05% by mass, and the obtained diluted solution was thinly cast on a support plate and dried. A gold-palladium alloy was vapor-deposited on the dried product, which was observed with a scanning electron microscope (manufactured by JEOL Ltd., equipped with a JSM7600F transmission electron detector) to determine the number average particle size.

  In the present invention, the emulsion polymerization of the monomer (i), the seed emulsion polymerization of the monomer (ii) and the seed emulsion polymerization of the monomer (iii) may be sequentially performed in one polymerization tank, The polymerization tank may be changed sequentially for each of the emulsion polymerization of the monomer (i), the seed emulsion polymerization of the monomer (ii) and the seed emulsion polymerization of the monomer (iii). In the present invention, it is preferable to perform each polymerization sequentially in one polymerization tank. Moreover, the temperature of the reaction system during the polymerization is preferably 30 to 120 ° C, more preferably 50 to 100 ° C.

  Further, in any of the emulsion polymerization of monomer (i), seed emulsion polymerization of monomer (ii) and seed emulsion polymerization of monomer (iii), a reactive ultraviolet absorber, for example, 2- [2-hydroxy-5- (2-methacryloyloxyethyl) phenyl] -2H-1,2,3-benzotriazole and the like can be added. A reactive ultraviolet absorber is introduced into the molecular chain of the acrylic multilayer polymer, and the ultraviolet resistance of the acrylic multilayer polymer is improved. The addition amount of the reactive ultraviolet absorber is preferably 0.05 to 5 parts by mass with respect to 100 parts by mass of the total amount of monomers used for the production of the acrylic multilayer polymer.

  Chain transfer agents can be used in each polymerization to control molecular weight. The chain transfer agent used for each polymerization is not particularly limited. Examples of chain transfer agents include alkyl mercaptans such as n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-hexadecyl mercaptan; xanthogen disulfides such as dimethylxanthogen disulfide and diethylxanthogen disulfide; tetrathiuram disulfide And thiuram disulfides such as halogenated hydrocarbons such as carbon tetrachloride and ethylene bromide. The amount of the chain transfer agent used can be appropriately set within a range in which each of the polymers (I), (II), and (III) can be adjusted to a predetermined molecular weight. The amount of the chain transfer agent used in the seed emulsion polymerization of the monomer (iii) can be appropriately set so that the acrylic multilayer polymer has a desired melt flow rate. The suitable amount of chain transfer agent used in each polymerization varies depending on the amount of polymerization initiator used in the polymerization. The amount of the chain transfer agent used in the seed emulsion polymerization of the monomer (iii) is preferably 0.05 to 2 parts by mass, more preferably 0.08 with respect to 100 parts by mass of the monomer (iii). -1 part by mass.

  Next, the latex obtained by the above polymerization is coagulated. The latex can be coagulated by a known method. Examples of the coagulation method include a freeze coagulation method, a salting out coagulation method, and an acid precipitation coagulation method. Of these, the freeze coagulation method is preferable because it does not require the addition of a coagulant as an impurity. Instead of latex coagulation, latex spray drying may be employed. Before the latex is coagulated or spray-dried, it is preferable to filter the latex with a wire mesh having an opening of 50 μm or less in order to remove foreign substances.

  The slurry obtained by coagulation is washed as necessary and then dehydrated. It is preferable to repeat washing and dehydration so that the acid value of the acrylic multilayer polymer is in a desired range. By washing and dehydrating the slurry, water-soluble components such as emulsifiers and catalysts can be removed from the slurry. The slurry can be washed and dehydrated by, for example, a filter press, a belt press, a gina centrifuge, a screw decanter centrifuge, or the like. It is preferable to use a decanter type centrifugal dehydrator from the viewpoint of productivity and washing efficiency. The slurry is preferably washed and dehydrated at least twice. As the number of washing and dehydration increases, the remaining amount of water-soluble components decreases. However, from the viewpoint of productivity, the number of washing and dehydration is preferably 3 times or less.

  The dehydration is performed so that the water content of the slurry is preferably less than 0.3% by mass, more preferably less than 0.2% by mass. Drying of the dehydrated slurry is preferably performed at a temperature of 40 to 80 ° C. in order to further reduce the water content while preventing deterioration of the polymer. The dehydrated slurry is dried with an average residence time, preferably 0.5 to 5 hours, more preferably 1 to 3 hours. The lower the water content after dehydration and drying, the better the warm water whitening resistance and the boiling water whitening resistance.

The acrylic multilayer polymer of the present invention can be made into a molding material by kneading alone or in combination with a thermoplastic resin and then pelletizing. The mass ratio of the thermoplastic resin / acrylic multilayer polymer is preferably 0/100 to 95/5, more preferably 10/90 to 90/10.
The thermoplastic resins that can be used in combination with the acrylic multilayer polymer of the present invention include polycarbonate polymers, vinyl chloride polymers, vinylidene fluoride polymers, methacrylic resins, ABS resins, AES resins, AS Examples thereof include resins and acrylic resins. Of these thermoplastic resins, acrylic resins are preferred.

  The acrylic resin used as the thermoplastic resin is preferably a resin having a structural unit derived from methyl methacrylate and a structural unit derived from a monofunctional monomer other than methyl methacrylate. The amount of the structural unit derived from methyl methacrylate in the acrylic resin is preferably 80 to 100% by mass, more preferably 85 to 100% by mass with respect to the mass of all the structural units of the acrylic resin. The amount of the structural unit derived from the monofunctional monomer other than methyl methacrylate in the acrylic resin is preferably 0 to 20% by mass, more preferably 1 to 15% by mass with respect to the mass of all structural units of the acrylic resin. %.

  Monofunctional monomers other than methyl methacrylate include methyl acrylate, ethyl acrylate, butyl acrylate, propyl acrylate, hexyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, benzyl acrylate, etc. Acrylic acid ester monomers: Ethyl methacrylate, butyl methacrylate, propyl methacrylate, hexyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, etc .; Vinyl acetate, styrene, p-methylstyrene Aromatic vinyl compounds such as o-methylstyrene, m-methylstyrene, α-methylstyrene and vinylnaphthalene; ethylenically unsaturated nitriles such as acrylonitrile and methacrylonitrile; acrylic acid; Methacrylic acid, alpha, such as crotonic acid, beta-unsaturated carboxylic acid; N- ethylmaleimide, and the like maleimide compounds such N- cyclohexyl maleimide. Of these, alkyl acrylates having 1 to 6 carbon atoms in the alkyl group are preferred. Monofunctional monomers can be used alone or in combination of two or more. The acrylic resin preferably does not contain a structural unit derived from a polyfunctional monomer.

  The acrylic resin used as the thermoplastic resin has a glass transition temperature of preferably 95 ° C. or higher, more preferably 100 ° C. or higher, and further preferably 105 ° C. or higher. The acrylic resin has a melt flow rate at 230 ° C. under a load of 3.8 kg, preferably 0.5 to 20 g / 10 minutes, more preferably 0.8 to 10 g / 10 minutes. The acrylic resin preferably has a weight average molecular weight of 60,000 to 150,000.

The acrylic resin is not particularly limited by the manufacturing method. For example, it can be obtained by performing a known polymerization reaction such as a radical polymerization reaction or an anionic polymerization reaction by a known polymerization method such as a bulk polymerization method or a solution polymerization method. A commercially available acrylic resin can be used. For example, manufactured by Kuraray Co., Ltd. parapet ^TM, Mitsubishi Rayon Co., Ltd. Acrypet ^TM, manufactured by Sumitomo Chemical Co., Ltd. SUMIPEX ^TM, Asahi Kasei Chemicals Co., Ltd. del Pets ^TM, DOW CHEMICAL Co., Ltd. Paragurasu ^TM and Orogurasu ^TM, etc. Can be mentioned. Moreover, the methacryl resin prescribed | regulated to ISO8257-1 may be sufficient. The acrylic resin can be mixed in an amount of preferably 5 to 40 parts by mass, more preferably 10 to 35 parts by mass with respect to 100 parts by mass of the acrylic multilayer polymer of the present invention.

  The acrylic multi-layer polymer of the present invention is a known resin such as an ultraviolet absorber, an antioxidant, a light stabilizer, an anti-aging agent, a plasticizer, a polymer processing aid, a lubricant, a dye, or a pigment, if necessary. Additives may be included. The total content of the additive for resin is preferably 1 to 10 parts by mass with respect to 100 parts by mass of the total amount of the acrylic multilayer polymer and the thermoplastic resin blended as necessary. The additive for resin may be added at the time of resin melting, may be dry blended with resin pellets, or may be added by a masterbatch method.

The polymer processing aid comprises 60% by mass or more of structural units derived from methyl methacrylate and 40% by mass or less of structural units derived from vinyl monomers other than methyl methacrylate, and has an intrinsic viscosity of 3 to 6 dl / g. It is a high molecular compound. Examples of the vinyl monomer include methacrylic acid esters such as ethyl methacrylate, butyl methacrylate and cyclohexyl methacrylate; aromatic vinyl compounds such as styrene, p-methylstyrene and α-methylstyrene; N-propylmaleimide And maleimide compounds such as N-cyclohexylmaleimide and N-o-chlorophenylmaleimide. The intrinsic viscosity of the polymer processing aid is preferably 3 to 6 dl / g. When the intrinsic viscosity is within this range, the effect of improving the film forming property tends to be high.
A commercially available product can be used as the polymer processing aid. Commercially available polymer processing aids, Mitsubishi Rayon Co., Ltd. Metablen ^TM, and the like Kaneka Co. Kane Ace ^TM, DOW CHEMICAL Co. Paraloid ^TM.

  Examples of the ultraviolet absorber include benzophenones, benzotriazoles, triazines, benzoates, salicylates, cyanoacrylates, succinic anilides, malonic esters, formamidines, and the like. These may be used alone or in combination of two or more. Among these, benzotriazoles (compounds having a benzotriazole skeleton) and triazines (compounds having a triazine skeleton) are preferable. Benzotriazoles or triazines have a high effect of suppressing resin degradation (for example, yellowing) due to ultraviolet rays.

  Examples of benzotriazoles include 2- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol (manufactured by BASF; trade name TINUVIN329), 2- (2H- Benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol (manufactured by BASF; trade name TINUVIN234), 2,2′-methylenebis [6- (2H-benzotriazole-2 -Yl) -4-tert-octylphenol] (manufactured by ADEKA; LA-31), 2- (5-octylthio-2H-benzotriazol-2-yl) -6-tert-butyl-4-methylphenol be able to.

  Examples of triazines include 2,4,6-tris (2-hydroxy-4-hexyloxy-3-methylphenyl) -1,3,5-triazine (manufactured by ADEKA; LA-F70) and its analogs. Certain hydroxyphenyltriazine-based ultraviolet absorbers (manufactured by BASF; CGL777, TINUVIN460, TINUVIN479, etc.), 2,4-diphenyl-6- (2-hydroxy-4-hexyloxyphenyl) -1,3,5-triazine, etc. Can be mentioned.

In addition, an ultraviolet absorber having a maximum molar extinction coefficient εmax at a wavelength of 380 to 450 nm of 1200 dm ³ · mol ⁻¹ cm ⁻¹ or less can be preferably used. Examples of such an ultraviolet absorber include 2-ethyl-2′-ethoxy-oxalanilide (manufactured by Clariant Japan, Inc .; trade name “Sandyuboa VSU”).

Since the acrylic multilayer polymer of the present invention is excellent in adhesiveness with a thermoplastic resin, it is suitable for producing a laminate having a layer made of the acrylic multilayer polymer of the present invention and a layer made of a thermoplastic resin. ing. The laminate is not particularly limited by its production method. For example, a method for producing a laminate comprising separately melting and coextruding the acrylic multilayer polymer of the present invention and a thermoplastic resin, a molded product made of a thermoplastic resin, such as a film, sheet, plate, etc. Further, a method for producing a laminate comprising press molding, coating extrusion molding, insert molding or in-mold molding of the acrylic multilayer polymer of the present invention, a molded body comprising the acrylic multilayer polymer of the present invention, for example, A method for producing a laminate including press molding, coating extrusion molding, insert molding or in-mold molding of a thermoplastic resin on a film, sheet, plate, etc., a molded body comprising the acrylic multilayer polymer of the present invention, and heat Examples include a method for producing a laminate including welding, bonding, pressure bonding and the like with a molded body made of a plastic resin.
Examples of thermoplastic resins that can be used in the laminate include polycarbonate polymers, vinyl chloride polymers, vinylidene fluoride polymers, methacrylic resins, ABS resins, AES resins, AS resins, the aforementioned acrylic resins, and the like. Can be mentioned.

  The acrylic multilayer polymer of the present invention can be applied to various uses. For example, billboard parts such as advertising towers, stand signboards, sleeve signboards, billboard signs, and rooftop signs; display parts such as showcases, partition plates, and store displays; fluorescent lamp covers, mood lighting covers, lamp shades, light ceilings, and light walls Lighting parts such as chandeliers; interior parts such as pendants and mirrors; building parts such as doors, domes, safety window glass, partitions, staircases, balconies, roofs of leisure buildings, sashes, kitchen doors, doors; Aircraft windshield, pilot visor, motorcycle, motorboat windshield, bus shading plate, automotive side visor, rear visor, head wing, headlight cover and other parts related to transport equipment; sound image nameplate, stereo cover, TV protection mask, automatic Electronic equipment parts such as display covers for vending machines Medical equipment parts such as incubators and X-ray parts; equipment-related parts such as machine covers, instrument covers, experimental devices, rulers, dials, observation windows; light guide plates and films for display devices, light guide plates for backlights, Optical parts such as films, LCD protective plates, Fresnel lenses, lenticular lenses, front plates of various displays, diffusers and reflectors; traffic-related parts such as road signs, guide plates, curved mirrors and sound barriers; automotive interior surfaces Materials, film materials such as mobile phone surface materials and marking films; members for household appliances such as canopy materials and control panels for washing machines, top panels for rice cookers; other greenhouses, large aquariums, box aquariums, clock panels, List bathtubs, sanitary, desk mats, game parts, toys, masks for facial protection when welding, etc. Can.

The acrylic multilayer polymer of the present invention is excellent in transparency and processability, and suppresses the bleeding out of the ultraviolet absorber, so that, for example, surface layers of building materials for indoor and outdoor use such as sashes, doors, kitchen doors, and various covers , Various terminal boards, printed wiring boards, speakers, microscopes, binoculars, cameras, watches, and other optical equipment, and video / optical recording / optical communication / information equipment related parts such as cameras, VTRs, projection TVs, etc. , Filters, prisms, Fresnel lenses, protective films for various optical disks (VD, CD, DVD, MD, LD, etc.) substrates, optical switches, optical connectors, liquid crystal displays, light guide films and sheets for liquid crystal displays, flat panel displays, flat Light guide film / sheet for panel display, plasma display, Light guide film / sheet for laser display, light guide film / sheet for electronic paper, retardation film / sheet, polarizing film / sheet, polarizing plate protective film / sheet, polarizer protective film / sheet, wavelength plate, light diffusion film / Sheet, prism film / sheet, reflective film / sheet, anti-reflection film / sheet, viewing angle widening film / sheet, anti-glare film / sheet, brightness enhancement film / sheet, display element substrate for liquid crystal and electroluminescence, touch panel, touch panel It can be suitably applied to applications such as a light guide film / sheet for use, a spacer between various front plates and various modules.
Specifically, for example, various liquid crystal display elements such as mobile phones, digital information terminals, pagers, navigation, in-vehicle liquid crystal displays, liquid crystal monitors, light control panels, displays for OA devices, displays for AV devices, and electroluminescence displays It can be used for an element or a touch panel. In addition, from the point of being excellent in weather resistance, for example, building interior and exterior members, curtain walls, roof members, roofing materials, window members, gutters, exteriors, wall materials, flooring materials, construction materials, The present invention is particularly preferably applicable to known building materials such as road construction members, retroreflective films / sheets, agricultural films / sheets, lighting covers, signboards, and translucent sound insulation walls.

  The acrylic multilayer polymer of the present invention can be applied to a solar cell surface protective film, a solar cell sealing film, a solar cell back surface protective film, a solar cell base film, a gas barrier film protective film, etc. for solar cell applications. It is.

  The film of the present invention comprises the acrylic multilayer polymer of the present invention. The film of the present invention can be obtained by a known film forming method. Examples of the film forming method include an extrusion molding method, an inflation molding method, a blow molding method, a melt casting method, and a solution casting method. Of these, the extrusion method is preferred. According to the extrusion molding method, a film having improved toughness, excellent handleability, and excellent balance between toughness, surface hardness and rigidity can be obtained. The temperature of the resin discharged from the extruder is preferably set to 160 to 270 ° C, more preferably 220 to 260 ° C.

  Among the extrusion molding methods, from the viewpoint of obtaining a film having good surface smoothness, good specular gloss, and low haze, the acrylic multilayer polymer of the present invention is extruded from a T die in a molten state, and then two of them are extruded. A method including forming a film by sandwiching the above mirror roll or mirror belt is preferable. The mirror roll or the mirror belt is preferably made of metal. The linear pressure between the pair of mirror rolls or the mirror belt is preferably 2 N / mm or more, more preferably 10 N / mm or more, and even more preferably 30 N / mm or more.

  Moreover, it is preferable that the surface temperature of a mirror surface roll or a mirror surface belt is 130 degrees C or less. The pair of mirror rolls or mirror belts preferably have at least one surface temperature of 60 ° C. or higher. When such a surface temperature is set, the resin discharged from the extruder can be cooled at a speed faster than natural cooling, and a film having excellent surface smoothness and low haze can be easily produced.

  The film of the present invention may be subjected to a stretching treatment. By the stretching treatment, a film that has high mechanical strength and is difficult to crack can be obtained. The stretching method is not particularly limited, and examples thereof include a uniaxial stretching method, a simultaneous biaxial stretching method, a sequential biaxial stretching method, and a tuber stretching method. The temperature at the time of stretching is preferably from 100 to 200 ° C, more preferably from 120 to 160 ° C, from the viewpoint that the film can be stretched uniformly and a high-strength film can be obtained. Stretching is usually performed at 100 to 5000% / min on a length basis. The stretching is preferably performed so that the area ratio is 1.5 to 8 times. A film with less heat shrinkage can be obtained by heat setting after stretching.

  The thickness of the film of the present invention is not particularly limited, but is preferably 0.2 mm or less, more preferably 1 to 200 μm, still more preferably 10 to 100 μm, and still more preferably 15 to 75 μm. The thinner the film is, the lower the ultraviolet absorbing ability. Since the acrylic multilayer polymer of the present invention hardly generates bleed-out even when a large amount of an ultraviolet absorber is added, it is easy to increase the ultraviolet absorbing ability in a thin film.

The film of the present invention has high transparency, high heat resistance, and even during molding at high temperature, the occurrence of mold stains, bleeding out, etc. is suppressed, and the occurrence of problems due to transpiration of ultraviolet absorbers can be reduced. In addition, because it can be made thin, a polarizer protective film, a retardation film, a liquid crystal protective plate, a surface material for a portable information terminal, a display window protective film for a portable information terminal, a light guide film, silver nanowires and carbon nanotubes on the surface It is suitable for coated transparent conductive films, front plate applications for various displays, and the like. In particular, since the film of the present invention has a small retardation, it is suitable for a polarizer protective film.
The film of the present invention has high transparency and processability, and even if a large amount of an ultraviolet absorber is added, it is difficult for bleeding out to occur. Therefore, a film for building materials, an IR cut film, a crime prevention film, a scattering prevention film, and a decorative film , Metal decorative film, solar cell back sheet, flexible solar cell front sheet, shrink film, in-mold label film, gas barrier film base film.

  A functional layer can be provided on at least one side of the film or sheet of the present invention. Examples of the functional layer include a hard coat layer, an antiglare layer, an antireflection layer, an antisticking layer, a light diffusion layer, an antiglare layer, an antistatic layer, an antifouling layer, a slippery layer, and a gas barrier layer.

  Next, the present invention will be described more specifically with reference to examples and comparative examples. “Part” and “%” used in Examples and Comparative Examples all mean “part by mass” and “% by mass”.

Abbreviations such as monomers used in Examples and Comparative Examples are as follows.
MMA: methyl methacrylate ALMA: allyl methacrylate MA: methyl acrylate BA: butyl acrylate n-OM: n-octyl mercaptan

  The physical properties of the acrylic multilayer polymers obtained in the examples and comparative examples were measured as follows.

[Particle size of acrylic multilayer polymer in latex: D]
The latex containing the acrylic multilayer polymer was diluted with ion-exchanged water so as to have a concentration of 0.05% by mass, and the obtained diluted solution was thinly cast on a support plate and dried. A gold-palladium alloy was vapor-deposited on the dried product, which was observed with a scanning transmission electron microscope (manufactured by JEOL Ltd., JSM7600F) to determine the number average particle size.

[Acetone soluble content, acetone insoluble content, and acetone swelling degree: y]
A precisely weighed acrylic multilayer polymer powder 2 g (w0) was added to 100 ml of acetone and stirred at room temperature for 24 hours. The obtained liquid was put into a centrifuge tube and centrifuged at 5 ° C. and 20000 rpm for 120 minutes. The supernatant was then removed by decantation, leaving insolubles at the bottom of the settling tube. Acetone was added to the settling tube and stirred. Centrifugation was performed at 5 ° C. and 20000 rpm for 120 minutes. The supernatant was then removed by decantation. The insoluble matter in the state of absorbing acetone was taken out from the bottom of the settling tube, and its mass w1 was measured. The insoluble matter in a state where acetone was absorbed was dried at 80 ° C. to obtain an insoluble matter containing no acetone, and its mass w2 was measured. The degree of acetone swelling of acetone-insoluble matter was calculated by the formula: 100 × w1 / w2. The amount of acetone soluble matter was calculated by the formula: 100 × (w0−w2) / w0. The amount of acetone insolubles was calculated by the formula: 100 × w2 / w0.
Acetone was removed from the supernatant with a rotary evaporator at 50 ° C. under reduced pressure, and the solid residue was dried at 80 ° C. to obtain an acetone-soluble component.

[Molecular weight of acetone-soluble matter]
6 mg of acetone-soluble component was dissolved in 10 ml of tetrahydrofuran to obtain a solution. By measuring the chromatogram under the following conditions by gel permeation chromatography (GPC) and converting it to the molecular weight of standard polymethyl methacrylate, the weight average molecular weight (Mw), number average molecular weight (Mn), molecular weight distribution (Mw) / Mn).
The baseline is that the slope of the peak on the high molecular weight side of the GPC chart changes from zero to positive when viewed from the earlier retention time, and the slope of the peak on the low molecular weight side is negative when viewed from the earlier retention time. A line connecting points that change from zero to zero.
GPC device: manufactured by Tosoh Corporation, HLC-8320
Detector: Differential refractive index detector Column: TSKgel SuperMultipore HZM-M manufactured by Tosoh Corporation and Super HZ4000 connected in series were used.
Eluent: Tetrahydrofuran Eluent flow rate: 0.35 ml / min Column temperature: 40 ° C
Calibration curve: Prepared using data of 11 kinds of standard polymethyl methacrylate.

[Aspect ratio of crosslinked elastic layer: z]
Using a capillograph (“Capillograph 1D” manufactured by Toyo Seiki Seisakusho Co., Ltd.), an acrylic multilayer polymer was formed into strands under the conditions of a temperature of 250 ° C., a capillary length of 39.99 mm, a capillary diameter of 1.00 mm, a test speed, and 100 mm / min. Molded. Using a microtome, the obtained strand was cut in a direction parallel to the flow direction (MD) at −100 ° C. to obtain a thin piece having a thickness of 40 nm. The flakes were dyed with ruthenium. The dyed thin piece was observed with a scanning transmission electron microscope (JSM7600F, manufactured by JEOL Ltd.) at an acceleration voltage of 25 KV and photographed (for example, see FIG. 1. The micron bar at the bottom white line of the photograph represents 100 nm). Twenty or more major and minor axes of the ruthenium-stained portion (section exposed portion of the crosslinked elastic body, oval black-gray portion in FIG. 1) were measured. The number average value (aspect ratio) of the ratio of the major axis to the minor axis was calculated.

[Particle diameter of crosslinked elastic layer: d]
Using a hydraulic press molding machine, mold size 50 mm x 120 mm, press temperature 250 ° C, preheating time 3 minutes, press pressure 50 kg / cm ² , press time 30 seconds, cooling temperature 20 ° C, cooling pressure 50 kg / cm ^{2. An} acrylic multilayer polymer was molded into a 3 mm flat plate under the condition of cooling time of 10 minutes. Using a microtome, the obtained flat plate was cut in a direction parallel to the long side at −100 ° C. to obtain a flake having a thickness of 40 nm. The flakes were dyed with ruthenium. The stained flakes were observed with a scanning transmission electron microscope (JSM7600F, manufactured by JEOL Ltd.) at an acceleration voltage of 25 KV and photographed. 20 or more diameters of the ruthenium-stained portion (section exposed portion of the crosslinked elastic body) were measured. The number average value (average diameter) of the diameter of the ruthenium-stained portion was calculated.

  The effect exhibited by the acrylic multilayer polymer obtained in Examples and Comparative Examples was evaluated as follows.

[Film forming properties]
The acrylic multilayer polymer powder was dried at 80 ° C. for 12 hours. Thereafter, the acrylic multilayer polymer was extruded by a single screw extruder with a 65φ vent equipped with a hanger coat die having a die width of 400 mm under conditions of an extrusion temperature of 250 ° C., a die temperature of 250 ° C., and a die lip opening of 0.6 mm. Then, it was taken up and cooled by a metal roll having a roll temperature of 80 ° C. to obtain a film having a thickness of 50 μm. About the obtained film, thickness of 20 points was measured at intervals of 50 mm in the MD direction, and a standard deviation, an average value, and a coefficient of variation (= standard deviation / average value × 100) were calculated from the measured values. When the coefficient of variation was 2% or less, it was rated as “A”, and when the coefficient of variation was over 2%, it was rated as “B”.

[Haze]
A small piece of 50 mm × 50 mm was cut out from the film, and the haze (H0) of the small piece was measured using a haze meter MH-150 manufactured by Murakami Color Research Laboratory.

[Hot water whitening resistance]
The 50 mm × 50 mm pieces were immersed in boiling water for 4 hours. Then, it was dried at 100 ° C. for 8 hours. About this small piece, haze (H1) was measured using the Haze meter MH-150 by Murakami Color Research Laboratory. A case where the difference between H0 and H1 was 2 or less was rated as “A”, and a case where the difference between H0 and H1 was more than 2 was evaluated as “B”.

[Stress whitening resistance]
The piece of the test piece broken in the tensile elongation measurement test was visually observed.
The case where the entire surface of the piece was whitened was rated as “C”, the case where only the fractured portion was whitened as “B”, and the case where there was no whitened portion as “A”.

[Ductility]
The film was punched out to obtain a JIS K 7127 (ISO 572-3) type 1B test piece. The test piece was pulled at 200 mm / min, and the elongation immediately before breaking was measured. This measurement was performed in the direction of extrusion (MD) and the direction perpendicular to the direction (TD). The tensile elongation was calculated by the formula: tensile elongation (%) = (elongation just before breaking / distance between chucks) × 100. The larger the tensile elongation, the higher the ductility.

[Tear strength]
The tear strength of the film was measured according to JIS K 7128-1. This measurement was performed in the direction of extrusion (MD) and the direction perpendicular to the direction (TD).

[Folding resistance]
The film was cut to obtain a test piece having a length of 120 mm and a width of 15 mm. For the test piece, using a MIT test machine (Toyo Seiki Seisakusho Co., Ltd.), in accordance with JIS P 8115, under conditions of a load of 2.45 N, a bending angle of 135 °, a bending speed of 175 rpm, and a tip gripper tip radius of 0.38 mm. Then, the bending was repeated and the number of folding reciprocations until breaking was counted. This was performed 5 times for each of the extrusion direction (MD) and the direction perpendicular to the extrusion direction (TD), and the average value (folding strength) of the bending reciprocation was calculated.

Example 1
A reactor equipped with a stirrer, thermometer, nitrogen gas inlet tube, monomer inlet tube and reflux condenser was charged with 1050 parts of deionized water, 1 part of sodium dodecylbenzenesulfonate and 0.05 part of sodium carbonate, and reacted. The inside of the vessel was sufficiently replaced with nitrogen gas to make it substantially free of oxygen. The temperature in the reactor was 80 ° C. To this, 0.1 part of a 3% aqueous solution of potassium persulfate was added and stirred for 5 minutes. Thereafter, 26.2 parts of monomer mixture (i) consisting of 49.9% MMA, 49.9% BA, and 0.2% ALMA was continuously added dropwise over 20 minutes. After completion of the dropwise addition, the polymerization reaction was further performed for at least 30 minutes so that the polymerization conversion rate was 98% or more.

  Next, 0.05 part of a 3% aqueous solution of potassium persulfate was added to the reactor and stirred for 5 minutes. Thereafter, 157.4 parts of a monomer mixture (ii) consisting of 5% MMA, 93.5% BA, and 1.5% ALMA was continuously added dropwise over 40 minutes. After completion of the dropwise addition, the polymerization reaction was further performed for at least 30 minutes so that the polymerization conversion rate was 98% or more.

Next, 0.5 part of a 3% aqueous solution of potassium persulfate was added to the reactor and stirred for 5 minutes. Thereafter, 341.1 parts of a mixture (iii) consisting of 87.2% MMA, 12.5% BA, and 0.3% n-OM was continuously added dropwise over 100 minutes. After completion of the dropwise addition, the polymerization reaction was further performed for at least 60 minutes so that the polymerization conversion rate was 98% or more to obtain a latex containing the acrylic multilayer polymer (A1).
Subsequently, the latex containing the acrylic multilayer polymer (A1) was frozen at −30 ° C. for 4 hours. The frozen latex was poured into 80 ° C. warm water twice as much as that and dissolved to obtain a slurry. The slurry was held at 80 ° C. for 20 minutes. Then, it dehydrated and dried at 70 ° C. to obtain a powder of an acrylic multilayer polymer (A1).

  The powder of the acrylic multilayer polymer (A1) was supplied to a single screw extruder with a vent, melted and kneaded at an average residence time of 3.5 minutes at 265 ° C., and extruded from a T die into a film. The extruded film-like molten resin was wound around a mirror roll to obtain a film having a thickness of 50 μm. The evaluation results are shown in Table 2.

(Example 2)
A reactor equipped with a stirrer, thermometer, nitrogen gas inlet, monomer inlet tube and reflux condenser was charged with 1050 parts of deionized water, 1 part of sodium dodecylbenzenesulfonate and 0.05 part of sodium carbonate, and reacted. The inside of the vessel was sufficiently replaced with nitrogen gas to make it substantially free of oxygen. The temperature in the reactor was 80 ° C. To this, 0.1 part of a 3% aqueous solution of potassium persulfate was added and stirred for 5 minutes. Thereafter, 13.1 parts of a mixture (i-1) consisting of MMA 89.9%, BA 9.9%, and ALMA 0.2% was continuously added dropwise over 10 minutes. After completion of the dropwise addition, the polymerization reaction was further performed for 20 minutes. Then 13.1 parts of a mixture (i-2) consisting of MMA 49.9%, BA 49.9%, and ALMA 0.2% was added dropwise continuously over 10 minutes. After completion of the dropwise addition, the polymerization reaction was further performed for at least 0 minutes so that the polymerization conversion rate was 98% or more.

  Next, 0.05 part of a 3% aqueous solution of potassium persulfate was added to the reactor and stirred for 5 minutes. Thereafter, 157.4 parts of a mixture (ii) consisting of 5% MMA, 93.5% BA, and 1.5% ALMA was continuously added dropwise over 40 minutes. After completion of the dropwise addition, the polymerization reaction was further performed for at least 30 minutes so that the polymerization conversion rate was 98% or more.

Next, 0.5 part of a 3% aqueous solution of potassium persulfate was added to the reactor and stirred for 5 minutes. Thereafter, 341.1 parts of a mixture (iii) consisting of 95% MMA, 4.7% BA, and 0.3% n-OM was continuously added dropwise over 100 minutes. After completion of the dropwise addition, the polymerization reaction was further performed for at least 60 minutes so that the polymerization conversion rate was 98% or more to obtain a latex containing an acrylic multilayer polymer (A2) having an average particle diameter of 100 nm.
Subsequently, the latex containing the acrylic multilayer polymer (A2) was frozen at −30 ° C. for 4 hours. The frozen latex was poured into 80 ° C. warm water twice as much as that and dissolved to obtain a slurry. The slurry was held at 80 ° C. for 20 minutes. Thereafter, it was dehydrated and dried at 70 ° C. to obtain a powder of an acrylic multilayer polymer (A2).

  The powder of the acrylic multilayer polymer (A2) was supplied to a single screw extruder with a vent, melted and kneaded at an average residence time of 3.5 minutes at 265 ° C., and extruded from a T die into a film. The extruded film-like molten resin was wound around a mirror roll to obtain a film having a thickness of 50 μm. The evaluation results are shown in Table 2.

(Examples 3 to 6)
Powders of acrylic multilayer polymers (A3) to (A6) in the same manner as in Example 1 except that the mixture (i), the mixture (ii) and the mixture (iii) were changed to the compositions and addition amounts shown in Table 1. And a film was obtained. The evaluation results are shown in Table 2.

(Comparative Examples 1-5 and 8-9)
Acrylic multilayer polymers (A7) to (A11) and (A14) in the same manner as in Example 1 except that the mixture (i), the mixture (ii) and the mixture (iii) were changed to those having the composition ratio shown in Table 1. ) To (A15) powders and films were obtained. The evaluation results are shown in Table 2.

(Comparative Example 6)
The mixture (i), the mixture (ii) and the mixture (iii) were changed to those having the composition ratio shown in Table 1, and the amount of sodium dodecylbenzenesulfonate was changed to 2 parts. A powder and a film of the multilayered polymer (A12) were obtained. The evaluation results are shown in Table 2.

(Comparative Example 7)
The same method as in Example 1 except that the mixture (i), the mixture (ii) and the mixture (iii) were changed to those having the composition ratio shown in Table 1 and the amount of sodium dodecylbenzenesulfonate was changed to 0.5 part. A powder and a film of an acrylic multilayer polymer (A13) were obtained. The evaluation results are shown in Table 2.

Claims (6)

An acrylic multilayer polymer comprising an outer layer made of a thermoplastic polymer (III) and a crosslinked elastic layer covered in contact with the outer layer,
The crosslinked elastic body layer has an intermediate layer made of a crosslinked rubber polymer (II) and an inner layer made of the crosslinked polymer (I) and covered in contact with the intermediate layer,
The crosslinked polymer (I) is composed of 40 to 98.95% by mass of structural units derived from methyl methacrylate, 1 to 59.95% by mass of structural units derived from monofunctional monomers other than methyl methacrylate, and polyfunctional. Consisting of 0.05 to 0.4 mass% of structural units derived from monomers,
The crosslinked rubber polymer (II) is derived from a structural unit derived from methyl methacrylate and a structural unit derived from alkyl acrylate having an alkyl group having 1 to 8 carbon atoms and / or a conjugated diene. A structure comprising 80 to 98% by mass of structural units and 1.0 to 1.7% by mass of structural units derived from a polyfunctional monomer, and derived from a polyfunctional monomer in the crosslinked rubber polymer (II) The ratio of the mass of the structural unit derived from the polyfunctional monomer in the crosslinked polymer (I) to the mass of the unit is 0.05 to 0.25,
Thermoplastic polymer (III) is 80 to 100% by mass of structural units derived from methyl methacrylate, and 0 to 20% by mass of structural units derived from an alkyl acrylate ester having an alkyl group having 1 to 8 carbon atoms. Consists of
The amount of the crosslinked polymer (I) is 1 to 30% by mass, the amount of the crosslinked rubber polymer (II) is 20 to 49% by mass, and the amount of the thermoplastic polymer (III) is based on the acrylic multilayer polymer. 50-79% by mass,
The amount of acetone-soluble component contained in the acrylic multilayer polymer is x% by mass with respect to the mass of the acrylic multilayer polymer, and the acetone swelling degree of acetone-insoluble component contained in the acrylic multilayer polymer is y% by mass. Ruthenium observed by an electron microscope in a section obtained by melting a strand obtained by melting an acrylic multilayer polymer at 250 ° C. using a capillograph and flowing out at a shear rate of 1220 sec ^−1. When the number average value of the ratio of the major axis to the minor axis of the stained portion is z, and the number average value of the diameter of the ruthenium stained portion observed by the electron microscope is d nanometer, the formula: x · y -The value calculated by z / d is 400 or more and 1000 or less,
Acrylic multilayer polymer.   The acrylic multilayer polymer according to claim 1, wherein the acetone-soluble component has a ratio (Mw / Mn) of the weight average molecular weight to the number average molecular weight of 2 to 3.   The acrylic multilayer polymer according to claim 1 or 2, wherein y is 500 to 650.   The methacrylic multilayer polymer according to any one of claims 1 to 3, wherein z is 1.3 to 3.0.   The acrylic multilayer polymer according to any one of claims 1 to 4, wherein x is 48 to 60 and d is 60 to 110.   A film comprising the acrylic multilayer polymer according to any one of claims 1 to 5.

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