JP2011046862A - Acrylic resin composition and acrylic film prepared by molding the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acrylic resin composition capable of providing a film which can be stably processed for the thermal transfer of a reflector element and is excellent in transparency, film processability, and weatherability. <P>SOLUTION: The acrylic resin composition includes a (meth)acrylic resin containing an acrylic polymer (A) and the following lubricant (C). The acrylic polymer (A) is prepared by copolymerizing at least one monomer component selected from the group consisting of methacrylate, acrylate, and other copolymerizable vinyl monomers in the presence of a crosslinked acrylic polymer having a structure of at least one layer, which is prepared by polymerizing monomer components including an acrylic monomer and a polyfunctional monomer having two or more nonconjugated double bonds per molecule which is copolymerizable with the acrylic monomer. The acrylic polymer has a weight average particle size of 300-3,000 Å. The lubricant (C) is an ester compound of a hydroxyl group-containing compound having a hydroxyl value of 30-185 mg/g and a carboxyl group-containing compound. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an acrylic resin composition, an acrylic film formed by molding the acrylic resin composition, and use thereof.

  A general retroreflective sheet has a laminated structure composed of a plurality of layers including a surface protective layer, an intermediate layer as necessary, and a reflective element layer.

  In the form in which the prism is formed on one surface of the reflective element layer, the reflective element layer is required to have thermal transferability (prism moldability). Therefore, polycarbonate resin has been conventionally used from the viewpoint of thermal transferability. However, the polycarbonate resin has poor weather resistance. For this reason, an acrylic resin is laminated as a surface protective layer on a polycarbonate resin reflective element layer to produce a product.

  On the other hand, an acrylic resin is used for the reflective element layer from the viewpoint of transparency required for the retroreflective sheet. Generally, it is commercialized in a form in which a surface protective layer made of an acrylic resin is laminated on a reflective element layer made of an acrylic resin. As used in the surface protective layer, the acrylic resin has an advantage of excellent weather resistance. However, with a conventional retroreflective sheet that uses acrylic resin for the reflective element layer, the curved part tends to whiten or crack when attached to or pasted on a undulating substrate, or the retroreflective sheet is made thin. There is a problem that is not easy. As a sheet or film having transparency and excellent processability such as whitening resistance, for example, an acrylic resin composition containing a cross-linked elastic polymer such as Patent Document 1 or Patent Document 2 is formed. It has been known. However, since the film made of an acrylic resin composition containing these cross-linked elastic polymers is exclusively for in-mold molding, no study has been made on thermal transferability.

Japanese Patent Application No. 2001-138614 Japanese Patent Application No. 9-238910

  Therefore, the present invention provides an acrylic resin composition that can be stably processed even when a reflective element or the like is thermally transferred.

  As a result of intensive studies, the present inventors have found that, when a (meth) acrylic resin containing an acrylic polymer having a specific particle size and a specific lubricant are used, transparency, film processability, and weather resistance are used. As a result, the inventors have found that it is possible to form a film having excellent heat transfer properties as well as excellent heat transfer properties, thereby completing the present invention.

That is, this invention is an acrylic resin composition containing the (meth) acrylic resin and the lubricant (C) described below.
Acrylic polymer (A):
From a monomer component (a-1) comprising an acrylic monomer and a polyfunctional monomer having two or more non-conjugated double bonds per molecule that can be copolymerized with the acrylic monomer In the presence of the cross-linked acrylic polymer (A-1) having a structure of at least one layer, at least selected from the group consisting of methacrylic acid esters, acrylic acid esters and other vinyl monomers copolymerizable Obtained by copolymerizing a kind of monomer component (a-2),
An acrylic polymer having a weight average particle diameter of 300 to 3,000 mm.
Lubricant (C):
An ester compound of a hydroxyl group-containing compound and a carboxyl group-containing compound having a hydroxyl value of 30 to 185 mg / g.

  The hydroxyl group-containing compound is preferably glycerin and / or pentaerythritol. The carboxyl group-containing compound is preferably a fatty acid and / or a saturated dicarboxylic acid. The fatty acid is preferably an alkyl group having 13 to 25 carbon atoms.

  The (meth) acrylic resin may include at least one thermoplastic polymer (B) selected from the group consisting of methacrylic acid esters, acrylic acid esters, and other copolymerizable vinyl monomers.

  The lubricant (C) is preferably contained in an amount of 0.1 to 7 parts by weight with respect to 100 parts by weight of the (meth) acrylic resin.

  The acrylic resin composition can contain a colorant.

  The acrylic film of the present invention is formed by molding the above acrylic resin composition.

  The acrylic film preferably has a thickness of 10 to 500 μm.

  The acrylic film may have a prism type retroreflective element formed on one side.

  The acrylic film of the present invention is used for the retroreflective sheet of the present invention.

  The retroreflective sheet may be an acrylic film in which a prismatic retroreflective element is formed on one surface of the retroreflective sheet.

  According to the acrylic resin composition of the present invention, a film excellent in thermal transferability (prism moldability) and excellent in transparency, film processability and weather resistance can be obtained. If the film of the present invention is used for a retroreflective sheet, the retroreflective sheet can be thinned.

It is a block diagram of a retroreflection sheet. It is a block diagram of the retroreflective sheet | seat made into the single layer. It is sectional drawing of the acrylic film which thermally transferred the prism type retroreflection element. It is a conceptual diagram of the measuring method of the retroreflection coefficient by JISZ8714.

  In the acrylic resin composition of the present invention, a compound obtained by esterifying a hydroxyl group-containing compound and a carboxyl group-containing compound having a hydroxyl value of 30 to 185 mg / g is used as the lubricant (C).

  Examples of the hydroxyl group-containing compound include glycerin, pentaerythritol, ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, triethylene glycol, hydrogenated bisphenol. A, bisphenol dihydroxypropyl ether, trimethylol ethane, trimellilol propane, trishydroxymethylaminomethane, dipentaerythritol and the like. Among these, glycerin and pentaerythritol are preferable from the viewpoint of industrial products that can be obtained at low cost. These compounds may be used alone or in combination of two or more.

  The carboxyl group-containing compound is not particularly limited, but from the viewpoint of light resistance and high reactivity, a compound having a primary carboxyl group is preferable, and a fatty acid and / or a saturated dicarboxylic acid is preferable.

  The fatty acid is preferably a saturated monocarboxylic acid from the viewpoint of oxidative degradation. From the viewpoint of gas generation due to unesterified products, those having an alkyl group with 13 to 25 carbon atoms are preferred, and examples include myristic acid, palmitic acid, margaric acid, stearic acid, behenic acid, and montanic acid. More preferably, the alkyl group has 15 to 25 carbon atoms, and more preferably 17 to 25 carbon atoms.

  The saturated dicarboxylic acid may be a chain type or may have a cyclic structure in the molecule. From the viewpoint of suppressing the intramolecular dehydration condensation reaction, those having 3 to 8 carbon atoms are preferred. For example, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and the like can be mentioned.

  As the carboxyl group-containing compound, the above compounds may be used alone or in combination of two or more.

  The hydroxyl value of the ester compound of the lubricant (C) is 30 to 185 mg / g, preferably 60 to 160 mg / g. If the ester compound has a hydroxyl value of 30 to 185 mg / g, the film-forming property, transparency and prism moldability will be good. Here, the hydroxyl value is a value determined in accordance with JIS K 0070-1992, and specifically, as described later.

  The ester compound of the lubricant (C) preferably has an acid value of 25 mg / g or less, more preferably 20 mg / g or less, and still more preferably 15 mg / g or less, from the viewpoint of reducing unreacted products. Here, the acid value is a value determined in accordance with JIS K 2501-2003, and is specifically as described below.

  The content of the lubricant (C) is preferably 0.1 to 7 parts by weight and more preferably 0.5 to 5 parts by weight with respect to 100 parts by weight of the (meth) acrylic resin. If the amount is less than 0.1 part by weight, the prism moldability may not be good. On the other hand, if it exceeds 7 parts by weight, the film formability and transparency may not be good.

  The (meth) acrylic resin used in the acrylic resin composition of the present invention contains the following acrylic polymer (A).

  The acrylic polymer (A) of the present invention is selected from the group consisting of methacrylic acid esters, acrylic acid esters, and other copolymerizable vinyl monomers in the presence of the crosslinked acrylic polymer (A-1). Obtained by copolymerizing at least one monomer component (a-2).

  The crosslinked acrylic polymer (A-1) includes an acrylic monomer, a polyfunctional monomer having two or more non-conjugated double bonds per molecule that can be copolymerized with the acrylic monomer, A crosslinked acrylic polymer having a structure of at least one layer, comprising a monomer component (a-1) containing

  In the present invention, the acrylic monomer means an acrylic ester, a methacrylic ester and an ethylenically unsaturated monomer.

  Examples of the acrylate ester include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and n-octyl acrylate. Among them, acrylic acid alkyl esters are preferable, and alkyl groups having 1 to 8 carbon atoms are more preferable. These may be used alone or in combination of two or more.

  Examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate and the like. Among them, methacrylic acid alkyl esters are preferable, and alkyl groups having 1 to 4 carbon atoms are more preferable. These may be used alone or in combination of two or more.

  Examples of the ethylenically unsaturated monomer include vinyl halides such as vinyl chloride and vinyl bromide, vinyl cyanides such as acrylonitrile and methacrylonitrile, vinyl esters such as vinyl formate, vinyl acetate and vinyl propionate, and styrene. Aromatic vinyl derivatives such as vinyltoluene and α-methylstyrene, vinylidene halides such as vinylidene chloride and vinylidene fluoride, acrylic acid and salts thereof such as acrylic acid, sodium acrylate, calcium acrylate, β-hydroxy acrylate Acrylic acid alkyl ester derivatives such as ethyl, dimethylaminoethyl acrylate, glycidyl acrylate, acrylamide, N-methylol acrylamide, methacrylic acid and salts thereof such as methacrylic acid, sodium methacrylate, calcium methacrylate, Examples include methacrylic acid alkyl ester derivatives such as methacrylamide, β-hydroxyethyl methacrylate, dimethylaminoethyl methacrylate, and glycidyl methacrylate. Among these, aromatic vinyl derivatives are preferable from the viewpoint of adjusting the refractive index with a high refractive index monomer. These copolymerizable ethylenically unsaturated monomers may be used alone or in combination of two or more.

  From the viewpoint of film processability, the monomer component (a-1) preferably contains 40% by weight or more of acrylic acid ester in 100% by weight of acrylic monomer, more preferably 50%. % By weight or more.

  The proportion of the methacrylic acid ester used in the monomer component (a-1) is preferably 0 to 40% by weight, more preferably 0 to 20% by weight, in 100% by weight of the acrylic monomer.

  The ethylenically unsaturated monomer used for the monomer component (a-1) is preferably 0 to 20% by weight, more preferably 0 to 10% by weight in 100% by weight of the acrylic monomer. .

  A polyfunctional monomer having two or more non-conjugated double bonds per molecule that can be copolymerized with an acrylic monomer (hereinafter, sometimes simply referred to as “polyfunctional monomer”). It is a component that affects the gel content of the cross-linked acrylic polymer and the graft ratio to the cross-linked acrylic polymer, and is used as a cross-linking agent, a graft crossing agent, and the like. For example, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, dipropylene glycol dimethacrylate or acrylates of these methacrylates, vinyl group-containing polyfunctional monomers such as divinylbenzene, divinyl adipate, diallyl phthalate, diallyl maleate, Examples include allyl group-containing polyfunctional monomers such as allyl acrylate, allyl methacrylate, triallyl cyanurate, and triallyl isocyanurate. You may use these individually or in combination of 2 or more types.

  It is preferable that the usage-amount of a polyfunctional monomer is 0.2-2 weight part with respect to 100 weight part of acrylic monomers, More preferably, it is 0.3-1.5 weight part. When the amount used is less than 0.2 parts by weight, the transparency may decrease, and when it exceeds 2 parts by weight, the prism moldability may decrease, which is not preferable.

  The production method of the crosslinked acrylic polymer (A-1) in the present invention is not particularly limited, and a known emulsion polymerization method, emulsion-suspension polymerization method, suspension polymerization method, bulk polymerization method or solution polymerization method can be applied. However, the emulsion polymerization method is particularly preferable.

  In the emulsion polymerization method of the cross-linked acrylic polymer (A-1), the monomer component (a-1) or the type and ratio of the polyfunctional monomer can be changed to be multilayered. The smaller the difference in refractive index of the monomer component (a-1) used, the better. If the difference is large, the transparency tends to decrease.

  In the crosslinked acrylic polymer (A-1), the glass transition temperature (Tg) in each layer is preferably less than 0 ° C, more preferably less than -5 ° C. If Tg is 0 ° C. or higher, film processability may be reduced. Here, Tg was calculated using the formula of “Polymer Hand Book (Polymer Hand Book (J. Brandrup, Interscience, 1989)”) using the formula of Fox (however, polyfunctional monomer). It is calculated without including body, initiator, and surfactant.

  The monomer component (a-2) may be at least one selected from the group consisting of methacrylic acid esters, acrylic acid esters and other copolymerizable vinyl monomers. From the viewpoint of transparency, it is preferable to contain a methacrylic acid ester, and an acrylic acid ester and / or another copolymerizable vinyl monomer may be used in combination as necessary.

  Examples of the methacrylic acid ester that can be used for the monomer component (a-2) include those similar to the methacrylic acid ester used for the crosslinked acrylic polymer (A-1). Among these, methacrylic acid alkyl esters are preferable, and alkyl groups having 1 to 4 carbon atoms are more preferable. These methacrylic acid esters may be used alone or in combination of two or more.

  Examples of the acrylate ester that can be used for the monomer component (a-2) include the same acrylate esters as those used for the crosslinked acrylic polymer (A-1). Among these, an alkyl acrylate ester is preferable, and an alkyl group having 1 to 8 carbon atoms is more preferable. These acrylic acid esters may be used alone or in combination of two or more.

  Examples of other copolymerizable vinyl monomers that can be used for the monomer component (a-2) include vinyl halides such as vinyl chloride and vinyl bromide, vinyl cyanides such as acrylonitrile and methacrylonitrile, Vinyl esters such as vinyl formate, vinyl acetate and vinyl propionate, aromatic vinyl derivatives such as styrene, vinyl toluene and α-methylstyrene, vinylidene halides such as vinylidene chloride and vinylidene fluoride, acrylic acid, sodium acrylate and acrylic Acrylic acid such as calcium acid and salts thereof, β-hydroxyethyl acrylate, dimethylaminoethyl acrylate, glycidyl acrylate, acrylamide, N-methylol acrylamide, etc., alkyl ester derivatives, methacrylic acid, sodium methacrylate, Methacrylic acid Examples include methacrylic acid such as lucium and its salts, methacrylic acid alkyl ester derivatives such as methacrylamide, β-hydroxyethyl methacrylate, dimethylaminoethyl methacrylate, glycidyl methacrylate, and the like. Among these, aromatic vinyl derivatives are preferable from the viewpoint of economy and refractive index adjustment, and styrene is particularly preferable. These other copolymerizable vinyl monomers may be used alone or in combination of two or more.

  The monomer component (a-2) preferably contains 80% by weight or more of methacrylic acid ester in 100% by weight of the monomer component (a-2), and from the viewpoint of solvent resistance, 85% by weight or more is preferable. 90% by weight or more is more preferable. The upper limit may be 100% by weight.

  The monomer component (a-2) preferably contains 20 to 0% by weight or less of the acrylic acid ester in 100% by weight of the monomer component (a-2). From the viewpoint of solvent resistance, the monomer component (a-2) is 15 to 0. % By weight or less is preferable, and 10 to 0% by weight or less is more preferable.

  The monomer component (a-2) is used within the range of 0 to 20% by weight of the other copolymerizable vinyl monomer in 100% by weight of the monomer component (a-2). It is possible.

  Examples of the method for producing the acrylic polymer (A) include a suspension polymerization method and an emulsion polymerization method, and it is preferable to produce the acrylic polymer (A) by an emulsion polymerization method.

  In the emulsion polymerization method, it is preferable to use a usual polymerization initiator, particularly a polymerization initiator that generates free radicals. Specific examples of such a polymerization initiator include inorganic peroxides such as potassium persulfate and sodium persulfate, and organic peroxides such as cumene hydroperoxide and benzoyl peroxide. In addition, oil-soluble initiators such as azobisisobutyronitrile are also used. These may be used alone or in combination of two or more.

  These polymerization initiators may be used as a normal redox type polymerization initiator in combination with a reducing agent such as sodium sulfite, sodium thiosulfate, sodium formaldehyde sulfoxylate, ascorbic acid, ferrous sulfate and the like.

  The surfactant used in the emulsion polymerization method is not particularly limited, and any surfactant for normal emulsion polymerization can be used. Examples thereof include anionic surfactants such as sodium alkyl sulfate, sodium alkylbenzene sulfonate, and sodium laurate, and nonionic surfactants such as a reaction product of alkylphenols and ethylene oxide. These surfactants may be used alone or in combination of two or more. Further, if necessary, a cationic surfactant such as alkylamine hydrochloride may be used.

  The polymer latex obtained by the emulsion polymerization method is separated and recovered by usual coagulation (for example, coagulation using a salt) and washing, or by treatment such as spraying or freeze-drying.

  The copolymerization of the monomer component (a-2) may be carried out by adding a chain transfer agent. The chain transfer agent is preferably selected from those usually used for radical polymerization, and specific examples thereof include, for example, alkyl mercaptans having 2 to 20 carbon atoms, mercapto acids, thiophenol, carbon tetrachloride and the like. These are used alone or in combination of two or more.

The graft ratio of the monomer component (a-2) to the crosslinked acrylic polymer (A-1) is preferably 50 to 140% by weight, more preferably 60 to 120% by weight. When the graft ratio is 50 to 140% by weight, both the prism moldability and the film processability are good. Here, the graft ratio means that 1 g of the acrylic polymer (A) dry resin powder obtained by emulsion polymerization or the like is dispersed and dissolved in 50 ml of methyl ethyl ketone, and the insoluble matter can be separated with a centrifuge (30,000 rpm × 2 Hrs). This is a value calculated by the following formula after separating the soluble content and measuring the weight of the insoluble content that has been sufficiently dried by vacuum drying as the rubber-graft content.
Graft rate (%)
= ((Weight of rubber / graft-weight of crosslinked acrylic polymer (A-1)) / weight of crosslinked acrylic polymer (A-1)) × 100
The weight average particle diameter of the acrylic polymer (A) is 300 to 3000 mm, preferably 500 to 2000 mm, more preferably 600 to 1800 mm, and most preferably 700 to 1500 mm. When the weight average particle diameter is 300 to 3000 mm, both transparency and film processability are good. Here, the weight average particle diameter of the acrylic polymer (A) is a temperature of 23 ° C. ± 2 ° C. and a humidity of 50 using a sample obtained by diluting the acrylic polymer (A) latex to a solid content concentration of 0.02%. It is a value measured from a light transmittance at a wavelength of 546 nm using a spectrophotometer (manufactured by HITACHI, Spectrophotometer U-2000) at% ± 5%.

  The reduced viscosity of the methyl ethyl ketone soluble part of the acrylic polymer (A) is preferably 0.35 dl / g or less, more preferably 0.32 dl / g or less. If it exceeds 0.35 dl / g, the prism moldability may deteriorate. Here, the reduced viscosity is a value obtained by measuring a methyl ethyl ketone-soluble component in a 0.3% N, N′-dimethylformamide solution at 30 ° C.

  The (meth) acrylic resin used in the acrylic resin composition of the present invention has at least one monomer component selected from methacrylic acid ester, acrylic acid ester and other vinyl monomers copolymerizable. You may contain the thermoplastic resin (B) which consists of.

  The thermoplastic polymer (B) is composed of a monomer component containing 80% by weight or more of methacrylic acid ester and 0 to 20% by weight of acrylic acid ester and / or other copolymerizable vinyl monomer. It is preferable.

  As the methacrylic acid ester, those similar to the methacrylic acid ester used in the above-mentioned crosslinked acrylic polymer (A-1) can be used, and methacrylic acid alkyl ester is preferable, and the alkyl group has 1 to 4 carbon atoms. Is more preferable. Methacrylic acid esters may be used alone or in combination of two or more.

  The content of the methacrylic acid ester is preferably 80% by weight or more, more preferably 85% by weight in 100% by weight of the monomer component. If it is less than 80% by weight, the solvent resistance may decrease.

  Examples of other copolymerizable vinyl monomers include vinyl halides such as vinyl chloride and vinyl bromide, vinyl cyanides such as acrylonitrile and methacrylonitrile, vinyl esters such as vinyl acetate and vinyl propionate, and styrene. , Aromatic vinyl such as α-methylstyrene, aromatic vinyl derivatives such as o-chloroethylene, m-chloroethylene, acrylic acid such as vinylidene chloride, acrylic acid and sodium acrylate, and salts thereof, and acrylic acid esters such as acrylamide Derivatives, methacrylic acid such as methacrylic acid and sodium methacrylate or salts thereof, and methacrylic acid ester derivatives such as methacrylamide. Among these, styrene is preferable from the viewpoints of economy and refractive index adjustment. These may be used alone or in combination of two or more.

  As the acrylic ester, those similar to the acrylic ester used in the crosslinked acrylic polymer (A-1) can be used, and among them, an acrylic alkyl ester is preferable, and the alkyl group has 1 to 8 carbon atoms. Those are more preferred. These acrylic acid esters are used alone or in combination of two or more.

  The total content of the acrylate ester and / or other copolymerizable vinyl monomer is preferably 0 to 20% by weight, more preferably 0 to 10% by weight in 100% by weight of the monomer component. is there.

  The reduced viscosity of the methyl ethyl ketone soluble part of the thermoplastic polymer (B) is preferably 0.35 dl / g or less, more preferably 0.34 dl / g or less, and still more preferably 0.32 dl / g or less. If it exceeds 0.35 dl / g, the prism moldability may deteriorate. The measurement of the reduced viscosity here is the same as the measurement of the reduced viscosity of the acrylic polymer (A).

  The thermoplastic polymer (B) is obtained by polymerizing these monomer components. The polymerization method is not particularly limited, and can be performed by suspension polymerization, emulsion polymerization, bulk polymerization, or the like. In order to bring the reduced viscosity of the polymer within the above range, a chain transfer agent may be used. Various conventionally known chain transfer agents can be used, and mercaptans are particularly preferred. The amount of chain transfer agent to be used must be appropriately determined depending on the type and composition of the monomer.

  The acrylic resin composition of the present invention preferably has a gel fraction of 25 to 50% by weight, more preferably 30 to 50% by weight, and still more preferably 100% by weight of (meth) acrylic resin. Is 30 to 45% by weight. If the gel fraction is 25 to 50% by weight, there is an advantage that crackability, bending whitening resistance, and prism formability are improved.

  The gel content (%) in the acrylic resin composition is calculated by multiplying the gel content (%) of the acrylic polymer (A) by the blending ratio of the acrylic polymer (A).

The gel content of the acrylic polymer (A) was determined by collecting a predetermined amount of the dry resin powder of the acrylic polymer (A) on a 100-mesh wire net, immersing it in methyl ethyl ketone for 48 hours, and drying it under reduced pressure to remove the methyl ethyl ketone. Then, the weight which became constant weight is read, and it calculates by following Formula (1).
Gel content of acrylic polymer (A) (%)
= (Weight after re-drying / weight of sample collected) × 100 (1)
The gel content (%) in the acrylic resin composition is obtained by multiplying the gel content (%) of the acrylic polymer (A) by the blending ratio of the acrylic polymer (A), from the following formula (2). Calculated. Here, the blending ratio of the acrylic polymer (A) refers to the blending ratio of the acrylic polymer (A) to the acrylic resin composition. Gel content in acrylic resin composition (%)
= (Gel content of acrylic polymer (A) (%)) x (Blend ratio of acrylic polymer (A)) (2)
Depending on the purpose, the acrylic resin composition of the present invention may be added with one or a combination of two or more additives such as an antioxidant and an ultraviolet absorber for increasing stability to heat and light. Good. A coloring agent may be added as needed for the purpose of coloring. For example, organic dyes such as thioxanthene, coumarin, perylene, methine, benzopyran, thioindigo, anthraquinone, and organic pigments such as phthalocyanine Can be added. Furthermore, polycarbonate resins other than acrylic resins, polyester resins, and the like may be combined.

  The acrylic resin composition of the present invention is particularly useful as a film. For example, transparency, solvent resistance, prism moldability, and the like can be obtained by an ordinary melt extrusion method such as an inflation method, a T-type die extrusion method, or a calendar method. An acrylic film excellent in crackability, film processability and the like is obtained.

  The thickness of the film is suitably about 10 to 500 μm, preferably 30 to 300 μm, and more preferably 75 to 200 μm.

  The acrylic film of the present invention can be used for applications such as a retroreflective sheet, an antireflection film, a polarizing film, a diffusion film, a light guide plate, and a surface protective film.

  The acrylic film of the present invention is suitable for thermal transfer of a reflective element on one side, and for example, a prism type retroreflective element such as a triangular pyramid prism shown in FIG. 3 can be formed. Examples of the shape of the reflective element include a hemisphere, a quadrangular pyramid, and a triangular frustum. The height of the element is preferably 100 μm or less.

  The acrylic film of the present invention is used as a reflective element layer of a general retroreflective sheet having a laminated structure formed of a plurality of layers such as a surface protective layer and a reflective element layer or an intermediate layer as shown in FIG. May be. Moreover, as shown in FIG. 2, it can be used as a surface layer of a retroreflective sheet in which a surface protective layer and an antireflection layer are integrated. Such a single layer can be manufactured at a lower cost than a general retroreflective sheet and can be thinned.

  The retroreflective sheet of the present invention can be suitably used for safety materials such as signs such as road signs and construction signs, license plates of vehicles such as automobiles and motorcycles, rear-end collision prevention boards, clothing, and lifesaving equipment.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated more concretely, these do not limit this invention at all. In the following description, “part” or “%” represents “part by weight” and “% by weight”, respectively, unless otherwise specified.

  Measurement and evaluation in Examples and Comparative Examples were performed using the following conditions and methods.

(1) Polymerization conversion rate The obtained acrylic polymer (A) latex was dried in a hot air dryer at 120 ° C. for 1 hour to determine the amount of solid components, and polymerized by 100 × solid component amount / charged monomer. Conversion (%) was calculated.

(2) Gel content rate of acrylic resin composition The gel content rate in the acrylic resin composition is the ratio of the acrylic polymer (A) to the gel content rate (%) of the acrylic polymer (A). Calculated by multiplication.

The gel content of the acrylic polymer (A) was determined by collecting a predetermined amount of the dry resin powder of the acrylic polymer (A) on a 100-mesh wire net, immersing it in methyl ethyl ketone for 48 hours, and drying it under reduced pressure to remove the methyl ethyl ketone. Thereafter, the constant weight was read and calculated according to the following formula (1).
Gel content of acrylic polymer (A) (%)
= (Weight after re-drying / weight of sample collected) × 100 (1)
The gel content (%) in the acrylic resin composition is obtained by multiplying the gel content (%) of the acrylic polymer (A) by the blending ratio of the acrylic polymer (A), from the following formula (2). Calculated.
Gel content in acrylic resin composition (%)
= (Gel content of acrylic polymer (A) (%)) x (ratio of acrylic polymer (A) in acrylic resin composition)) (2)
(3) Glass transition temperature The values (MMA; 105 ° C, BA; -54 ° C, ST; 100 ° C) described in "Polymer Hand Book (J. Brandrup, Interscience, 1989)" Fox), but not including the polyfunctional monomer, initiator, and surfactant.

(4) Graft rate 1 g of the dry resin powder of the acrylic polymer (A) is dispersed and dissolved in 50 ml of methyl ethyl ketone (MEK), and the insoluble content and the soluble content are separated with a centrifugal separator (30,000 rpm × 2 Hrs). The insoluble matter was sufficiently dried by vacuum drying, and the weight was measured as the rubber / graft content.
Graft rate (%)
= ((Weight of rubber / graft-weight of crosslinked acrylic polymer (A-1)) / weight of crosslinked acrylic polymer (A-1)) × 100
(5) Weight average particle diameter of the acrylic polymer (A) The temperature was 23 ° C. ± 2 ° C. and the humidity was obtained by diluting the obtained acrylic polymer (A) latex to a solid content concentration of 0.02%. The weight average particle diameter was determined from the light transmittance at a wavelength of 546 nm using a spectrophotometer (manufactured by HITACHI, Spectrophotometer U-2000) at 50% ± 5%.

(6) Reduced viscosity Methyl ethyl ketone (MEK) soluble content was measured at 30 ° C using a 0.3% N, N'-dimethylformamide solution. The unit is dl / g.

(7) Measurement of hydroxyl value Based on JIS K 0070-1992, it measured by the following analytical procedures and computed by the following formula.
-Preprocessing-
1) 4.0 g (2.35 mL) of perchloric acid was added to 400 mL of ethyl acetate.
2) 8 mL of acetic anhydride was added and left at room temperature for 30 minutes.
3) It cooled to 5 degreeC, 42 mL of cooled acetic anhydride was added, and it was left to stand at 5 degreeC for 1 hour.
4) The acetic anhydride solution was returned to room temperature.
5) 100 mL of water was added to 300 mL of pyridine to prepare pyridine + water (3 + 1).
―Measurement―
1) 3 g of sample was collected in a 100 mL beaker.
2) 10.0 mL of acetic anhydride solution was added and stirred for 15 minutes.
3) 2 mL of water and 10.0 mL of pyridine + water (3 + 1) were added and stirred for 5 minutes.
4) 10.0 mL of pyridine was added.
5) Titration was performed with a 0.5 mol / L potassium hydroxide / ethanol solution to determine the hydroxyl value.
6) A blank test was performed in the same manner.
Titration solution: 0.5 mo1 / L potassium hydroxide / ethanol solution (f = 1.00)
Reagents: Pure water, pyridine, ethyl acetate, perchloric acid (78%), acetic anhydride -calculation formula-
Hydroxyl value (mg / g) = (BL1-EPl) * TF * Cl * K1 / SIZE
EPl: Titration volume (mL)
BLl: Blank value (56.1542 mL)
TF: Factor of titrant (1.00)
Cl: Concentration conversion coefficient (28.05 mg / mL)
(Formula weight of potassium hydroxide 56.11 × 1/2)
Kl: Unit conversion factor (1)
SIZE: Sample collection amount (g)
(8) Measurement of acid value Based on JIS K 2501-2003, it measured with the following analysis procedures, and computed with the following formula.
―Measurement―
1) About 0.05 g of a sample was weighed and put into a 200 mL tall beaker.
2) 150 mL of titration solvent was added.
3) The liquid temperature was heated to 80 ° C. with a beaker heating device to dissolve the sample.
4) After the liquid temperature became constant at 80 ° C., titration was performed using a 0.1 mol / L potassium hydroxide / ethanol solution to determine the acid value.
Titration solution: 0.1 mol / L potassium hydroxide / ethanol solution (f = 1.00)
Titration solvent: xylene + dimethylformamide (1 + 1)
-a formula-
Acid value (mg / g) = EP1 × FA1 × C1 × K1 / SIZE
EP1: Titration volume (mL)
FA1: Factor of titrant (1.00)
C1: Concentration conversion value (5.611 mg / mL)
(0.1mol / L KOH 1mL potassium hydroxide equivalent)
Kl: coefficient (1)
SIZE: Sample collection amount (g)
(9) Transparency Using a Nippon Denshoku Industries Co., Ltd. haze meter (HAZE METER), the total light transmittance and haze value of a 150 μm thick film were measured by a conventional method. Measured at 23 ° C., the unit is%.

(10) Film-forming property A 150 μm-thick film was extruded by the T-die extrusion method and evaluated according to the following criteria.
◯: There is no appearance defect such as film breakage or streaks on the film surface, and the thickness is uniform and can be extruded stably.
X: Out of film, surface defects such as streaks on the film surface, and extrusion is unstable.

(11) Prism moldability Using a female mold (100 mm x 100 mm) in which triangular pyramid prisms are arranged in a close-packed manner, acrylic films (transparent, thickness 150 μm) are overlaid, and the triangular pyramid prism is hot pressed. The film was processed as shown in FIG. The hot press conditions were as follows: the resin temperature was 230 ° C. and 20 kg / cm ² pressure was pressed for 2 seconds. After cooling the resin temperature to 90 ° C., the prism film was peeled from the mold. The obtained prism film was subjected to the following evaluation.

  This female mold fabrication will be described. The triangular pyramid prism shape of this mold is a diamond bite (blade) having the tip angle according to the angle formed by the bottom surface and each side surface calculated from the dimensions shown below. A copper male mold was prepared in which a large number of triangular pyramid prisms having a convex shape of 100 μm were arranged in a close-packed manner. Using this copper male mold, a concave female mold whose nickel shape was inverted by electroforming was produced. Three types of diamond tools with tip angles of 64.24 °, 64.54 °, and 82.18 ° are prepared, and diamonds with a tip angle of 64.24 ° on a 100 mm × 100 mm copper plate with a flat ground surface. Using a cutting tool, parallel grooves having a V-shaped cross-section were cut in a repeating pattern so that the repetition pitch was 222 μm and the groove depth was 100 μm. Thereafter, using a diamond bite having a tip angle of 64.54 °, the repetitive pitch is 221 μm, the depth is 100 μm, and the cross-sectional shape is V-shaped so that the crossing angle with the side a1 is 66.64 °. Parallel grooves were cut in a repeating pattern. Further, using a diamond bite having a tip angle of 82.18 °, the repetition pitch is 202 μm, the depth is 100 μm, the intersection angle with side a1 is 56.81 °, and the intersection angle with side a3 is 56.56. Parallel grooves having a V-shaped cross-section were cut in a repeated pattern so as to have an angle.

  The retroreflectivity was evaluated using the obtained prism film based on the following conditions.

In accordance with JIS Z8714, the following items were measured in the layout shown in FIG. 4, and the retroreflection coefficient was calculated according to Equation 1 and Equation 2 (unit: Cd / Lx · m ² ). Specifically, a retroreflective performance measuring instrument NS-1 manufactured by Suga Test Instruments Co., Ltd. was used.
I = Er * L ² (1)
R ′ = I / (En * A) (2)
R ′: retroreflection coefficient I: luminous intensity of the sample observed from the light receiving position (unit: Cd)
Er: Illuminance (unit: Lx) on the light receiver in the arrangement of FIG. 4 (incident angle α: −4 °, observation angle β: 0.2 °)
En: Illuminance on the plane perpendicular to the incident light at the center position of the sample (unit: Lx)
L: Distance between the sample surface center and the light receiver (unit: m)
A: Area of sample surface (unit: m ² )
(12) Cutter test (crackability)
The film obtained at 23 ° C. was scratched 10 cm in length in the MD direction with a cutter, and the cracked state of the cut part was evaluated according to the following criteria. In the cutting with a cutter, the cutter blade edge was inclined 45 ° with respect to the film, and a length of 10 cm was cut in 2 seconds.
○: There is no crack in the cut part.
X: There exists a crack in a cut part.

(13) Folding whitening resistance The film obtained at 23 ° C. was bent once by 180 °, and the change of the bent portion was visually evaluated according to the following criteria.
○: No cracking (whitening) is observed.
X: Cracking (whitening) is observed.

(Synthesis Example 1) Synthesis of crosslinked acrylic polymer (A): P-1
200 parts by weight of water and OSA were added in the amounts shown in Table 1 into an 8 liter polymerization vessel equipped with a stirrer, thermometer, nitrogen gas inlet tube, monomer supply tube, reflux condenser, and the inside of the vessel was sufficiently filled with nitrogen gas. After the substitution to make it substantially free of oxygen, the internal temperature was set to 40 ° C., 5 parts by weight of the mixture (a-1-1) shown in Table 1 was added all at once, and after stirring for 10 minutes, the following substance sodium Formaldehyde sulfoxylate 0.11 part by weight Ferrous sulfate dihydrate 0.004 part by weight Ethylenediaminetetraacetic acid-2-sodium 0.001 part by weight was charged, and the mixture (a-1-2) shown in Table 1 was prepared. After continuously adding and polymerizing at a rate of 10 parts by weight / hour, the polymerization was continued for another 0.5 hours, and the mixture (a-1-3) shown in Table 1 was added at 12.7 parts by weight / hour. After continuously adding and polymerizing at a ratio, 1 more After continuing the polymerization for 0 hour, the polymerization conversion rate is set to 98% or more, the internal temperature is set to 60 ° C., and the mixture (a-2-1) shown in Table 1 is continuously added at a rate of 16.7 parts by weight / hour. After the polymerization, the polymerization was further continued for 1.0 hour, and then the polymerization conversion rate was set to 98% or more to terminate the polymerization to obtain an acrylic polymer (A) latex.

  The obtained latex was salted out with calcium chloride, washed with water and dried to obtain a dry powder (P-1) of acrylic polymerization (A).

Synthesis Example 3 Synthesis of Crosslinked Acrylic Polymer (A): P-2
The following substances were added to an 8 liter polymerization vessel equipped with a stirrer, thermometer, nitrogen gas introduction tube, monomer supply tube, reflux condenser:
Water 200 parts by weight Sodium formaldehyde sulfoxylate 0.15 parts by weight Ferrous sulfate dihydrate 0.006 parts by weight Ethylenediaminetetraacetic acid-2-sodium 0.0015 parts by weight and OSA in the amounts shown in Table 1 After charging and substituting the inside of the vessel sufficiently with nitrogen gas to make it substantially free of oxygen, the internal temperature was set to 60 ° C., and the mixture (a-1-1) shown in Table 1 was 12.0 parts by weight / Continuously added at a rate of time, after polymerization, the polymerization conversion rate was increased to 98% or more, and the polymerization was further continued for 0.5 hour. The mixture (a-2-1) shown in Table 1 was 15.6 wt. After continuously adding and polymerizing at a ratio of parts / hour, the polymerization was further continued for 1.0 hour and then the polymerization conversion rate was set to 98% or more to terminate the polymerization, thereby obtaining a latex.

  The obtained latex was salted out with calcium chloride, washed with water and dried to obtain a dry powder (P-2) of acrylic polymerization (A).

Each abbreviation in Table 1 represents the following substance.
OSA; Dioctyl sodium sulfosuccinate BA; Butyl acrylate MMA; Methyl methacrylate ST; Styrene CHP; Cumene hydroperoxide AMA; Allyl methacrylate tDM; Tertiary decyl mercaptan (Examples 1-11, Comparative Examples 1-5)
A dry powder of P-1 to 2 obtained as an acrylic polymer (A), and a methacrylic resin (MMA / MA = 94/6, reduced viscosity 0.29 dl / g, commercial product) as a thermoplastic polymer (B) Name: Sumipex LG6-A (manufactured by Sumitomo Chemical Co., Ltd.) was blended at the blending ratios shown in Tables 3 and 4, and then the ester compound shown in Table 2 as a lubricant (C) (trade name: Riquemar S200, etc .; manufactured by Riken Vitamin Co., Ltd.) Are blended at the blending ratios shown in Tables 3 and 4, and further, 1 part by weight of an ultraviolet absorber: TINUVIN234 (manufactured by Ciba Specialty Chemicals Co., Ltd.), 100 parts by weight of (meth) acrylic resin, and antioxidant. Agent: After blending AO60 (manufactured by ADEKA Co., Ltd.) at a blending ratio of 0.4 parts by weight, it was extruded at 210 ° C setting of a vent type extruder, pelletized, , The extruder 210 ° C. in T die extrusion molding machine into a film (thickness 150 [mu] m) at a die 240 ° C. setting. Various physical properties of the obtained film were evaluated by the above methods. The results are shown in Tables 3-4.

  As shown in Tables 3 and 4, the film molded with the acrylic resin composition of the present invention is excellent in film processability, transparency, and film moldability, and has a high retroreflection coefficient and excellent prism moldability. It is clear. Therefore, the acrylic film of the present invention is suitable for a retroreflective sheet. According to the acrylic film of the present invention, a retroreflective sheet in a form in which the surface protective layer and the reflective element layer are formed into a single layer is also possible.

10: Surface protective layer 11: Reflective element layer (triangular pyramid prism layer)
12: Prism-containing layer 13: Backing film 14: Joint location (convex support)
15: Air layer 21: Light source 22: Retroreflector sample (retroreflective sheet)
23: Light receiving aperture 24: Spectrophotometer α: Observation angle β: Irradiation angle (incident angle)
L: Observation distance

Claims (12)

An acrylic resin composition containing a (meth) acrylic resin containing the following acrylic polymer (A) and the following lubricant (C).
Acrylic polymer (A):
From a monomer component (a-1) comprising an acrylic monomer and a polyfunctional monomer having two or more non-conjugated double bonds per molecule that can be copolymerized with the acrylic monomer In the presence of the cross-linked acrylic polymer (A-1) having a structure of at least one layer, at least selected from the group consisting of methacrylic acid esters, acrylic acid esters and other vinyl monomers copolymerizable Obtained by copolymerizing a kind of monomer component (a-2),
An acrylic polymer having a weight average particle diameter of 300 to 3,000 mm.
Lubricant (C):
An ester compound of a hydroxyl group-containing compound and a carboxyl group-containing compound having a hydroxyl value of 30 to 185 mg / g.   The acrylic resin composition according to claim 1, wherein the hydroxyl group-containing compound is glycerin and / or pentaerythritol. The acrylic resin composition according to claim 1 or 2, wherein the carboxyl group-containing compound is a fatty acid and / or a saturated dicarboxylic acid. The said fatty acid is an acrylic resin composition of Claim 3 whose carbon number of an alkyl group is 13-25.   The (meth) acrylic resin is a thermoplastic resin (B) comprising at least one monomer component selected from the group consisting of methacrylic acid esters, acrylic acid esters and other copolymerizable vinyl monomers. The acrylic resin composition according to any one of claims 1 to 4, further comprising:   The acrylic resin composition according to any one of claims 1 to 5, wherein the lubricant (C) is contained in an amount of 0.1 to 7 parts by weight with respect to 100 parts by weight of the (meth) acrylic resin.   Furthermore, the acrylic resin composition in any one of Claims 1-6 containing a coloring agent.   The acrylic film formed by shape | molding the acrylic resin composition in any one of Claims 1-7.   The acrylic film of Claim 8 whose thickness is 10-500 micrometers.   The acrylic film according to claim 8 or 9, wherein a prism type retroreflective element is formed on one side.   A retroreflective sheet using the acrylic film according to claim 8.   A retroreflective sheet, wherein the surface layer of the retroreflective sheet is the acrylic film according to claim 10.