JP2005126517A - Colored acrylic resin film for surface material of retroreflective sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prepare a colored acrylic resin film which is used for the surface material of a retroreflective sheet and can satisfy a color phase and a reflection performance needed when used for the retroreflective sheet. <P>SOLUTION: This colored acrylic resin film for the surface material of the retroreflective sheet is characterized by having a chromaticity coordinate (x, y) in a XYZ color system in a range of (0.016, 0.381), (0.185, 0.340), (0.317, 0.436) and (0.224, 0.806), when the colored acrylic resin film side of a laminate of the colored acrylic resin film to a gray color oily color paper sheet having a Munsell number of N5.5 is measured in a standard light D65 condition under an illumination-light receiving geometrical condition (a) (45°irradiation, vertical light receiving) defined in JIS Z 8722, and having a Y value of ≥2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a skin material for a retroreflective sheet, and relates to a transparent and colored acrylic resin film that protects the retroreflective sheet and imparts design properties to the base material. The present invention relates to a colored acrylic resin film that can be used as a skin material for a retroreflective sheet used in the above-mentioned and protect the surface thereof, and can impart design properties.

  Retroreflective sheets that reflect incident light toward the direction of the light source have been well known in the past, and are used in various fields by taking advantage of their retroreflective properties and excellent visibility at night. For example, road signs, construction signs, etc. using a retroreflective sheet reflect light from a light source such as a headlight of a traveling vehicle at night or the like toward the light source direction, that is, the direction of the traveling vehicle. It provides excellent visibility to the driver of the vehicle who is the viewer of the vehicle and enables clear information transmission. Retroreflective sheets used as such road signs, construction signs, etc. are colored for good visibility, and characters and patterns are directly screen printed on the colored retroreflective sheets. It is formed by.

There are white, yellow, red, yellow-red, green, and blue as the types of colors of the colored retroreflective sheeting. For each color, the color range and the lower limit of the luminance rate (β) are defined in the standard. . For example, in the case of the JIS standard, the color of the green retroreflective sheet is JIS Z9117, and the condition of the standard light D65 is based on the illumination and light reception geometric condition a (45 ° illumination, vertical light reception) specified in JIS Z8722. The chromaticity coordinates (x, y) in the XYZ color system when measured in (0.1, 0.492), (0.191, 0.441), (0.157, 0.379) And (0.116, 0.387), and the lower limit of the luminance rate (β) is determined to be 0.04. Here, the luminance rate (β) is a value indicating the ratio of the sample luminance to the value of 1.00 as the value of the complete diffuse reflection surface.
Further, in ASTM D4956, the color of the green retroreflective sheet is such that the chromaticity coordinates (x, y) in the XYZ color system are (0.026, 0.399), (0.166, 0.364), It is within the range of (0.286, 0.446) and (0.207, 0.771), and the lower limit value of the Y value is 3.0.

  As a method of obtaining the colored retroreflective sheet as described above, it is obtained by kneading a colorant in any of the steps up to the production of the film in addition to the method of coloring the surface layer of the retroreflective sheet by printing. A method of laminating the colored film as a protective layer on the base material of the retroreflective sheet is conceivable. Among these methods, the latter is preferable in consideration of the reflection performance and manufacturing cost of the retroreflective sheet.

As a cover film for a retroreflective sheet, JP-A-62-24741 (Patent Document 1) and JP-A-62-24742 (Patent Document 2) are composed of a thermoplastic polymer and a multilayer structure polymer. A gel with a controlled gel content is disclosed. This film is excellent in weather resistance and processability. Furthermore, a retroreflective sheet using a colorless and transparent polymethylmethacrylate film and a method for producing the same are disclosed in Examples of JP-A-11-15415 (Patent Document 3). This film is excellent in impact resistance and weather resistance.
Although these films are excellent in weather resistance, workability, and impact resistance, none of the published publications mentions a colored retroreflective sheet and a method for obtaining the same.

On the other hand, although not assumed to be used as a skin material for a retroreflective sheet, various colored films and colored layers have been disclosed so far.
Among these, JP 2002-331619 A (Patent Document 4) has a weather resistance that can be used outdoors and a flexible marking film substrate that can be applied to a curved surface. A colored acrylic resin film is disclosed. The examples of this publication disclose that a colored acrylic resin film can be obtained by adding a titanium oxide pigment to a commercially available flexible acrylic raw material.

Japanese Patent Laid-Open No. 2001-253033 (Patent Document 5) describes a coloring for constituting a marking film having an appropriate film strength, flexibility and shape followability, and high color saturation and weather resistance. A transparent layer is disclosed. The examples of this publication disclose that a cyanine blue organic pigment is added to an acrylic urethane paint to obtain a blue colored transparent layer.
Japanese Patent Application Laid-Open No. 2002-49315 (Patent Document 6) discloses a colored substrate layer for constituting a marking film having excellent weather resistance and appropriate flexibility and shape followability. Examples of the publication disclose that a colored base layer is obtained by adding a white pigment to a vinyl chloride resin or adding cyanine blue to a polypropylene resin.

  However, although the colored acrylic resin film disclosed in the above-mentioned JP-A-2002-331619 (Patent Document 4) exhibits excellent performance as a colored layer for constituting a marking film, Does not mention the hue and transparency required when used as a retroreflective sheet. Furthermore, since the colored acrylic resin film 1 disclosed in the examples of the publication has 15 parts by mass of titanium oxide added to 100 parts by mass of the resin component and is inferior in transparency, the skin material of the retroreflective sheet Not as satisfactory.

  Moreover, although the base material layer disclosed in Japanese Patent Application Laid-Open No. 2001-253033 (Patent Document 5) shows very excellent performance as a colored layer for constituting a marking film, in this publication, There is no mention of specific hue and transparency when the thermoplastic resin is colored. Furthermore, the film containing 5 parts by mass of the cyanine blue organic pigment in the base layer with respect to 100 parts by mass of the resin disclosed in the examples of the publication does not provide the hue required as a retroreflective sheet. Further, since it is inferior in transparency, it is not satisfactory as a skin material for a retroreflective sheet.

  Furthermore, although the colored base material layer disclosed in Japanese Patent Application Laid-Open No. 2002-49315 (Patent Document 6) exhibits excellent performance as a colored layer for constituting a marking film, No mention of typical film hues. Furthermore, the colored base material layer described in the examples of the publication includes a vinyl chloride resin in which 45 parts by mass of a white pigment is added to 100 parts by mass of the resin, or 4 cyanine blue pigments to 100 parts by mass of the resin. It is a colored polypropylene resin composition added in parts by mass, and when this film is used as the skin of a retroreflective sheet, the hue required as a retroreflective sheet is not obtained, and the transparency is inferior. It is not satisfactory as a skin material.

As described above, a colored acrylic resin film that can be used as a skin material for a retroreflective sheet that satisfies the hue and reflection performance required when used as a retroreflective sheet has not been known. Therefore, development of colored acrylic resin film for the skin of the retroreflective sheet, specifically, the colored acrylic resin film for the skin of the retroreflective sheet that can satisfy the hue and reflection performance required when used as a retroreflective sheet is strongly desired. It was rare.
JP-A-62-4741 JP-A-62-4742 Japanese Patent Laid-Open No. 11-15415 JP 2002-331619 A JP 2001-253033 A JP 2002-49315 A

  Accordingly, an object of the present invention is to provide a colored acrylic resin film for the skin of a retroreflective sheet that can satisfy the hue and reflection performance required when used as a retroreflective sheet.

  As a result of intensive studies on the colored acrylic resin film for the retroreflective sheet, the present inventors kneaded a specific colorant into the acrylic resin film so that the chromaticity coordinates (x, y) are within a specific range. It has been found that by coloring, a colored acrylic resin film that can satisfy the hue and reflection performance required when used as a retroreflective sheet can be obtained, and the present invention has been achieved.

  That is, the colored acrylic resin film for the skin of the retroreflective sheet of the present invention is a colored acrylic resin film used as a skin material for the retroreflective sheet, and the colored acrylic resin film and a murine colored oily colored paper having a Munsell symbol of N5.5 XYZ color when the colored acrylic resin film side is measured under the condition of standard light D65 under the illumination and light reception geometric conditions a (45 ° illumination, vertical light reception) specified in JIS Z8722 The chromaticity coordinates (x, y) in the system are (0.016, 0.381), (0.185, 0.340), (0.317, 0.436) and (0.224, 0. 806), and the Y value is 2 or more.

Moreover, it is desirable that the colored acrylic resin film for the retroreflective sheeting of the present invention contains any one of a phthalocyanine colorant, a condensed polycyclic colorant, and an inorganic colorant.
The total light transmittance of the colored acrylic resin film is preferably 30% or more as measured by the method defined in JIS K7361-1.
The colored acrylic resin film for the skin of the retroreflective sheeting of the present invention is preferably composed of an acrylic resin composition containing the following multilayer structure polymer (I) and the following thermoplastic polymer (II).

[Multilayer structure polymer (I)]
From the center, the multilayer structure polymer (I) is composed of the innermost layer polymer (IA), the first intermediate layer polymer (IB), the second intermediate layer polymer (IC), and the outermost layer polymer ( ID) in the order of the multilayer structure polymer,
The innermost layer polymer (IA) includes at least an alkyl methacrylate (I-A1) having an alkyl group having 4 or less carbon atoms, an alkyl acrylate (I-A2) having an alkyl group having 8 or less carbon atoms, an aromatic system A polymer obtained by polymerizing a vinyl monomer (I-A3) and a polyfunctional monomer (I-A4), having a glass transition temperature of 10 ° C. or higher;
The first intermediate layer polymer (IB) includes at least an alkyl acrylate (I-B1) having an alkyl group having 8 or less carbon atoms, an aromatic vinyl monomer (I-B2), a polyfunctional monomer A polymer having a glass transition temperature of 0 ° C. or less, obtained by polymerizing the body (I-B3) and the graft crossing agent (I-B5),
The second intermediate layer polymer (IC) is composed of alkyl methacrylate (I-C1) having an alkyl group having 4 or less carbon atoms, alkyl acrylate (I-C2) having an alkyl group having 8 or less carbon atoms, and aromatic vinyl. A polymer obtained by polymerizing the monomer (I-C3) and the graft crossing agent (I-C4),
The outermost layer polymer (ID) is composed of an alkyl methacrylate (ID1) having an alkyl group having 4 or less carbon atoms, an alkyl acrylate (ID2) having an alkyl group having 8 or less carbon atoms, and an aromatic vinyl monomer. It is a polymer having a glass transition temperature of 50 ° C. or higher obtained by polymerizing the body (I-D3).

[Thermoplastic polymer (II)]
The thermoplastic polymer (II) comprises 50 to 100% by mass of an alkyl methacrylate unit having an alkyl group having 1 to 4 carbon atoms and 0 to 50% by mass of another vinyl monomer unit copolymerizable therewith. The polymer has a reduced viscosity (0.1 g of polymer dissolved in 100 ml of chloroform and measured at 25 ° C.) of 0.1 l / g or less.

The colored acrylic resin film for the retroreflective sheeting of the present invention is preferably made of an acrylic resin composition containing the following multilayer structure polymer (III).
[Multilayer structure polymer (III)]
The multilayer polymer (III) is a multilayer polymer arranged in the order of the innermost layer polymer (III-A), the intermediate layer polymer (III-B), and the outermost layer polymer (III-C) from the center. Yes,
The innermost layer polymer (III-A) is a polymer having units derived from alkyl acrylate (III-A1) having an alkyl group having 1 to 8 carbon atoms and units derived from graft crossing agent (III-A5). Yes,
The intermediate layer polymer (III-B) is a unit derived from an alkyl acrylate (III-B1) having an alkyl group having 1 to 8 carbon atoms, and an alkyl methacrylate (III-B2) having an alkyl group having 1 to 4 carbon atoms. And a polymer having a composition different from that of the innermost layer polymer (III-A), and a unit derived from the graft crossing agent (III-B5).
The outermost layer polymer (III-C) is a polymer having units derived from alkyl methacrylate (III-C1) having an alkyl group having 1 to 4 carbon atoms.

  The colored acrylic resin film for the skin of the retroreflective sheeting of the present invention comprises a colored acrylic resin film and an oily colored paper having a Munsell symbol of N5.5 superimposed on each other, and the colored acrylic resin film side is stipulated in JIS Z8722. The chromaticity coordinates (x, y) in the XYZ color system when measured under the condition of the standard light D65 under the geometric condition a (45 ° illumination, vertical light reception) of light reception is (0.016, 0 .381), (0.185, 0.340), (0.317, 0.436), and (0.224, 0.806), and the Y value is 2 or more, so recursion The hue and reflection performance required when used as a reflection sheet can be satisfied.

In addition, if the colored acrylic resin film for the skin of the retroreflective sheet of the present invention contains any one of a phthalocyanine colorant, a condensed polycyclic colorant, and an inorganic colorant, it is used as a retroreflective sheet. In this case, the hue and the reflection performance required for the above can be satisfied.
Moreover, if the total light transmittance of the colored acrylic resin film is 30% or more as measured by the method defined in JIS K7361-1, the reflection of the retroreflective sheet manufactured using the colored acrylic resin film as the skin material Visibility is very good when it is used for road signs etc. without performance degradation.

Moreover, if the colored acrylic resin film for the skin of the retroreflective sheet of the present invention is made of an acrylic resin composition containing the multilayer polymer (I) and the thermoplastic polymer (II), the weather resistance, The impact property becomes good, and the temperature dependency of transparency becomes small.
Further, if the colored acrylic resin film for the skin of the retroreflective sheet according to the present invention is made of an acrylic resin composition containing the multilayer polymer (III), the weather resistance and impact resistance are improved, and the transparency is improved. The temperature dependence of becomes smaller.

Hereinafter, the present invention will be described in detail.
<Colored acrylic resin film>
The colored acrylic resin film for the skin of the retroreflective sheeting of the present invention (hereinafter also referred to as a colored acrylic resin film) is formed by superimposing the colored acrylic resin film on a gray-colored oily colored paper having a Munsell symbol of N5.5. Chromaticity coordinates in the XYZ color system (x) when the film side is measured under the conditions of standard light D65 under illumination and light reception geometric conditions a (45 ° illumination, vertical light reception) specified in JIS Z8722 , Y) must be in the range of (0.016, 0.381), (0.185, 0.340), (0.317, 0.436) and (0.224, 0.806) Don't be.

  Here, “range of (0.016, 0.381), (0.185, 0.340), (0.317, 0.436) and (0.224, 0.806)” 1, (0.016, 0.381), (0.185, 0.340), (0.317, 0.436), (0.224, chromaticity coordinates (x, y)) 0.806) and the first (0.016, 0.381) coordinates are connected to each other by a straight line.

When a colored acrylic resin film having chromaticity coordinates (x, y) in this range is used as the skin material of the retroreflective sheet, the retroreflective sheet can satisfy the hue described in, for example, JIS Z9117, and reflect The visibility of the sheet can be increased.
Preferred ranges of chromaticity coordinates (x, y) are (0.016, 0.381), (0.185, 0.340), (0.317, 0.436) and (0.224, 0. 806), more preferably in the range of (0.056, 0.389), (0.166, 0.364), (0.286, 0.446) and (0.219, 0.720). is there.

  As an oily colored paper with a Munsell symbol of N5.5, the mouse color (Munsell symbol: N5.5) of the standard color card 230 of Nippon Color Research Co., Ltd. can be used.

The Y value of the colored acrylic resin film for the retroreflective sheeting of the present invention is defined by JIS Z8722 in which the colored acrylic resin film is superposed on a gray colored oily colored paper having a Munsell symbol of N5.5. It is a value measured under the condition of the standard light D65 according to the illumination and light reception geometric condition a (45 ° illumination, vertical light reception), and this Y value must be 2 or more.
When the Y value is 2 or more, when the colored acrylic resin film is used as a skin material of the retroreflective sheet, the hue of the retroreflective sheet can satisfy the standard of ASTM D4956 and used for road signs and the like. In this case, the visibility becomes good. A more preferable Y value is 3 or more.

  As described above, the colored acrylic resin film for the skin of the retroreflective sheeting of the present invention is formed by superimposing a colored acrylic resin film and a gray-colored oily colored paper having a Munsell symbol of N5.5 on the colored acrylic resin film side to JIS Z8722. The chromaticity coordinates (x, y) in the XYZ color system when measured under the conditions of the standard light D65 according to the specified illumination and light reception geometric condition a (45 ° illumination, vertical light reception) are (0. 016, 0.381), (0.185, 0.340), (0.317, 0.436) and (0.224, 0.806) and by setting the Y value to 2 or more The hue of the retroreflective sheet using this as a skin material can satisfy both the standards of JIS Z9117 and ASTM D4956.

  The total light transmittance of the colored acrylic resin film for the retroreflective sheeting of the present invention is preferably 30% or more as measured by JIS K7361-1. When the total light transmittance is less than 30%, the reflective performance of the retroreflective sheet manufactured using the colored acrylic resin film as a skin material tends to be lowered, and when used for a road sign, the visibility tends to deteriorate. This is not preferable. Further, the total light transmittance is preferably 32% or more, particularly preferably 34% or more.

<Acrylic resin>
The colored acrylic resin film for the skin of the retroreflective sheeting of the present invention is a film made of an acrylic resin composition containing an acrylic resin as a main component and a colorant or the like added thereto. By using the acrylic resin, it is possible to impart excellent weather resistance to the film.
The acrylic resin is not particularly limited, but the main raw material is at least one selected from the group consisting of methyl methacrylate, ethyl methacrylate, propyl methacrylate and butyl methacrylate, and acrylic acid having an alkyl group having 1 to 8 carbon atoms as necessary. Examples thereof include a single polymer or a copolymer obtained by using ester, vinyl acetate, vinyl chloride, styrene, acrylonitrile methacrylonitrile or the like as a copolymerization component. In addition, a multilayer structure polymer as described in JP-B-59-36646, JP-B-62-19309, JP-B-63-20459 and JP-A-63-77963 can be used. .

The preferred acrylic resin used for the colored acrylic resin film for the retroreflective sheeting of the present invention is, for example, an acrylic resin (L) that combines a multilayer structure polymer (I) and a thermoplastic polymer (II) described below, Or it is a multilayer structure polymer (III).
That is, since the retroreflective sheet is mainly used outdoors such as a road sign, it is preferable to use a skin material having good weather resistance and impact resistance. As a method of imparting this impact resistance, there is a method of containing a rubber component, etc., but in this case, the transparency of the skin material changes due to the change in environmental temperature, and the reflection performance important as a retroreflective sheet It may decrease or the hue of the retroreflective sheet may change. The colored acrylic resin film using the above-mentioned acrylic resin (L) and multilayer structure polymer (III) has good weather resistance and impact resistance, and the temperature dependency of transparency is small. Can be suitably used.
Hereinafter, the acrylic resin of the preferable form mentioned above is demonstrated concretely.

<Multilayer structure polymer (I)>
The acrylic resin (L) used in the present invention is preferably 20 to 90 parts by mass of the multilayer structure polymer (I) and 80 to 10 parts by mass of the thermoplastic polymer (II) ((I) + (II) = 100. Part by mass).

From the center, the multilayer structure polymer (I) is composed of the innermost layer polymer (IA), the first intermediate layer polymer (IB), the second intermediate layer polymer (IC), and the outermost layer polymer ( ID) in the order of the multilayer structure polymer,
The innermost layer polymer (IA) includes at least an alkyl methacrylate (I-A1) having an alkyl group having 4 or less carbon atoms, an alkyl acrylate (I-A2) having an alkyl group having 8 or less carbon atoms, an aromatic system A polymer obtained by polymerizing a vinyl monomer (I-A3) and a polyfunctional monomer (I-A4), having a glass transition temperature of 10 ° C. or higher;
The first intermediate layer polymer (IB) includes at least an alkyl acrylate (I-B1) having an alkyl group having 8 or less carbon atoms, an aromatic vinyl monomer (I-B2), a polyfunctional monomer A polymer having a glass transition temperature of 0 ° C. or less, obtained by polymerizing the body (I-B3) and the graft crossing agent (I-B5),
The second intermediate layer polymer (IC) is composed of alkyl methacrylate (I-C1) having an alkyl group having 4 or less carbon atoms, alkyl acrylate (I-C2) having an alkyl group having 8 or less carbon atoms, and aromatic vinyl. A polymer obtained by polymerizing the monomer (I-C3) and the graft crossing agent (I-C4),
The outermost layer polymer (ID) is composed of an alkyl methacrylate (ID1) having an alkyl group having 4 or less carbon atoms, an alkyl acrylate (ID2) having an alkyl group having 8 or less carbon atoms, and an aromatic vinyl monomer. It is a polymer having a glass transition temperature of 50 ° C. or higher obtained by polymerizing the body (I-D3).

Furthermore, the following configuration is preferable.
The innermost layer polymer (IA) is
30-99.7% by mass of acrylic methacrylate (I-A1) having an alkyl group having 4 or less carbon atoms,
0.1 to 69.8% by mass of an alkyl acrylate (I-A2) having an alkyl group having 8 or less carbon atoms,
Aromatic vinyl monomer (I-A3) 0.1-25% by mass,
Polyfunctional monomer (I-A4) 0.1-10% by mass, and graft crossing agent (I-A5) 0-5% by mass ((I-A1) + (I-A2) + (I-A3) ) + (I−A4) + (I−A5) = 100% by mass) is a polymer having a glass transition temperature (hereinafter referred to as Tg) of 10 ° C. or higher. A Tg of 10 ° C. or higher is preferred because the resulting colored acrylic resin film tends to have good transparency. The amount of the innermost layer polymer (IA) in the multilayer structure polymer (I) (100% by mass) is 2 to 35% by mass in terms of impact resistance of the resulting colored acrylic resin film. Is preferred.

The first intermediate layer polymer (IB) is
60-99.7% by mass of alkyl acrylate (I-B1) having an alkyl group having 8 or less carbon atoms,
Aromatic vinyl monomer (I-B2) 0.1-39.8 mass%
0.1 to 10% by mass of a polyfunctional monomer (I-B3),
Monomer (I-B4) having a copolymerizable double bond (0 to 20% by mass) and graft crossing agent (I-B5) 0.1 to 5% by mass ((I-B1) + (I-B2) ) + (I−B3) + (I−B4) + (I−B5) = 100 mass%), and is preferably a polymer having a Tg of 0 ° C. or less. A Tg of 0 ° C. or lower is preferable because the resulting colored acrylic resin film tends to have good impact resistance. Moreover, the quantity of the 1st intermediate | middle layer polymer (IB) which occupies for a multilayer structure polymer (I) (100 mass%) is 5-60 mass% at the point of the impact resistance of the colored acrylic resin film obtained. Preferably there is.

The second intermediate layer polymer (IC) is
Alkyl methacrylate (I-C1) having an alkyl group having 4 or less carbon atoms, 20 to 89.8% by mass,
10 to 79.8 mass% of alkyl acrylate (I-C2) having an alkyl group having 8 or less carbon atoms,
Aromatic vinyl monomer (I-C3) 0.1-25% by mass, and graft crossing agent (I-C4) 0.1-5% by mass ((I-C1) + (I-C2) + (I -C3) + (I-C4) = 100% by mass) is preferable. The amount of the second intermediate layer polymer (IC) in the multilayer structure polymer (I) (100% by mass) is preferably 2 to 20% by mass. Moreover, it is preferable that the latex particle diameter in the 2nd intermediate | middle layer polymer (IC) stage in manufacture of multilayer structure polymer (I) is 0.03-0.2 micrometer.

The outermost layer polymer (ID) is
Alkyl methacrylate (I-D1) 51 to 99.8% by mass having an alkyl group having 4 or less carbon atoms,
0.1 to 48.9% by mass of alkyl acrylate (I-D2) having an alkyl group having 8 or less carbon atoms, and 0.1 to 25% by mass of aromatic vinyl monomer (I-D3) ((I-D1 ) + (I−D2) + (I−D3) = 100 mass%) is preferably a polymer having a Tg of 50 ° C. or higher. A Tg of 50 ° C. or higher is preferred because the resulting colored acrylic resin film tends to have good heat resistance. Further, the amount of the outermost layer polymer (ID) in the multilayer structure polymer (I) (100% by mass) is 10 to 80% by mass in terms of heat resistance of the resulting colored acrylic resin film. preferable.

Here, Tg of a polymer is calculated | required by the following Fox formula, for example in the case of the copolymer which consists of monomer a, b, c ....
1 / Tg = ma / Tga + mb / Tgb + mc / Tgc ...
Tg: Tg [K] of copolymer, ma: mass fraction of monomer a, Tga: Tg [K] of homopolymer obtained from monomer a, mb: mass fraction of monomer b, Tgb: Tg [K] of the homopolymer obtained from the monomer b, mc: Mass fraction of the monomer c, Tgc: Tg [K] of the homopolymer obtained from the monomer c.

  The alkyl methacrylate (I-A1) having an alkyl group having 4 or less carbon atoms constituting the innermost layer polymer (IA) may be either linear or branched, for example, butyl methacrylate, propyl methacrylate, Examples include ethyl methacrylate and methyl methacrylate. These can be used alone or in admixture of two or more. Among these, methyl methacrylate is preferable from the viewpoint of transparency.

  Examples of the alkyl acrylate (I-A2) having an alkyl group having 8 or less carbon atoms include methyl acrylate, ethyl acrylate, butyl acrylate, propyl acrylate, 2-ethylhexyl acrylate, and the like. These can be used alone or in admixture of two or more. Of these, butyl acrylate is preferable from the viewpoint of Tg.

  Examples of the aromatic vinyl monomer (I-A3) include styrene, α-methylstyrene, paramethylstyrene, and the like. These can be used alone or in admixture of two or more. Of these, styrene is preferable from the viewpoint of economy.

  The polyfunctional monomer (I-A4) is a monomer having two or more copolymerizable double bonds in one molecule. Examples of the polyfunctional monomer (I-A4) include alkylene glycol dimethacrylates such as ethylene glycol dimethacrylate, 1,3-butylene dimethacrylate, 1,4-butylene glycol dimethacrylate, and propylene glycol dimethacrylate; Polyvinylbenzene such as divinylbenzene and trivinylbenzene; alkylene glycol diacrylate and the like. These can be used alone or in admixture of two or more. Among these, alkylene glycol dimethacrylate is preferable, and 1,3-butylene glycol dimethacrylate is more preferable.

  The graft crossing agent (I-A5) is a monomer having two or more different copolymerizable double bonds in one molecule. Examples of the graft crossing agent (I-A5) include copolymerizable α, β-unsaturated monocarboxylic acid or dicarboxylic acid allyl ester, methallyl ester, crotyl ester, triallyl cyanurate, triallyl isocyanurate, and the like. Is mentioned. These can be used alone or in admixture of two or more. Of these, allyl methacrylate and triallyl cyanurate are particularly preferable.

As the alkyl acrylate (I-B1) having an alkyl group having 8 or less carbon atoms constituting the first intermediate layer polymer (IB), the alkyl acrylate represented by (I-A2) may be used alone or in combination of two or more. Can be mixed and used.
As the aromatic vinyl monomer (I-B2), styrene, α-methylstyrene, paramethylstyrene and the like shown in (I-A3) can be used alone or in admixture of two or more.

  Examples of the polyfunctional monomer (I-B3) include ethylene glycol dimethacrylate, 1,3-butylene dimethacrylate, 1,4-butylene glycol dimethacrylate, and propylene glycol dimethacrylate represented by (I-A4). Alkylene glycol dimethacrylate; polyvinylbenzene such as divinylbenzene and trivinylbenzene; alkylene glycol diacrylate and the like can be used alone or in admixture of two or more. Among these, alkylene glycol dimethacrylate is preferable, and 1,3-butylene glycol dimethacrylate is more preferable.

  The monomer (I-B4) having a double bond capable of copolymerization is a monomer other than the above-mentioned monomers and copolymerizable with the above-mentioned monomers. For example, lower alkoxy acrylate , Acrylic monomers such as cyanoethyl acrylate, acrylamide, acrylic acid and methacrylic acid, styrene, alkyl-substituted styrene, acrylonitrile, methacrylonitrile and the like. These can be used alone or in admixture of two or more.

  As the graft crossing agent (I-B5), allyl ester, methallyl ester, crotyl ester, triallyl cyanurate of the copolymerizable α, β-unsaturated monocarboxylic acid or dicarboxylic acid shown in (I-A5) Triallyl isocyanurate can be used alone or in admixture of two or more. Of these, allyl methacrylate and triallyl cyanurate are particularly preferable.

  As the monomer and graft crossing agent constituting the second intermediate layer polymer (IC) and the outermost layer polymer (ID), the innermost layer polymer (IA) and the first intermediate layer weight The same thing as a unification (IB) is mentioned. These can be used alone or in admixture of two or more.

The final latex particle size of the multilayer structure polymer (I) is preferably 0.03 to 0.2 μm, more preferably 0.04 to 0.15 μm, and most preferably 0.05 to 0. .1 μm. When the final latex particle size becomes too large, not only the transparency is lowered, but also the transparency may change due to a temperature change. When used as a skin material for a retroreflective sheeting outdoors such as a road sign, if the transparency changes due to a change in outside air temperature, it is not preferable because it causes a reduction in reflection performance and a change in hue. On the other hand, if the particle size is too small, the impact resistance is lowered, which is not preferable.
The acrylic resin used as the skin material of the retroreflective sheet is preferably highly transparent in terms of reflection performance, and is mainly used outdoors such as road signs, so that it is preferable to have high impact resistance.

  Furthermore, in order to reduce the temperature dependence of the total light transmittance and the haze value, the amount of alkyl methacrylate having 4 or less carbon atoms in each layer in the multilayer polymer (I) is reduced by the first intermediate layer polymer (I- From B), the amount of the alkyl methacrylate monotonously increasing toward the second intermediate layer polymer (IC) and the outermost layer polymer (ID) and occupying the first innermost layer polymer (IA) is the first. The amount is preferably larger than the amount occupied in the intermediate layer polymer (IB).

  Aromatic vinyl monomer in each layer (IA), (IB), (IC), (ID) of the multilayer structure polymer (I) and having an alkyl group having 8 or less carbon atoms The mass ratio to the alkyl acrylate (aromatic vinyl monomer / alkyl acrylate) is preferably 5/95 to 50/50, and more preferably 10/90 to 30/70. As the mass ratio goes away from this range, the transparency decreases, and the reflection performance tends to decrease when used as a skin material for a retroreflective sheet.

As a method for producing the multilayer structure polymer (I), a sequential multi-stage polymerization method by an emulsion polymerization method is the most suitable polymerization method. The production of the multilayer structure polymer (I) is not particularly limited, and for example, by emulsion suspension polymerization method in which after emulsion polymerization, the outermost layer polymer is converted to a suspension polymerization system at the time of polymerization. It can be carried out.
In addition, although not particularly limited, when the multilayer structure polymer (I) is produced by emulsion polymerization, the monomer mixture that gives the innermost layer polymer (IA) is preliminarily mixed with water and a surfactant. An emulsion is preferably prepared by mixing, supplying this emulsion to the reactor and polymerizing it, and then supplying the monomer mixture constituting each remaining layer to the reactor in order and polymerizing.

  The monomer mixture that gives the innermost layer polymer (IA) was dispersed in water, in particular, by supplying an emulsion prepared by mixing with water and a surfactant in advance to the reactor and polymerizing it. In this case, a multilayer structure polymer in which the number of particles having a diameter of 55 μm or more present in the dispersion is 0 to 50 per 100 g of the multilayer structure polymer (I) can be easily obtained. A colored acrylic resin film using the multilayer structure polymer (I) thus obtained as a raw material has a characteristic that the number of fish eyes in the film is small, and is preferable because the appearance is good.

  As the surfactant used in preparing the emulsion, anionic, cationic and nonionic surfactants can be used, and anionic surfactants are particularly preferable. Examples of the anionic surfactant include rosin soap; potassium oleate, sodium stearate, sodium myristate, sodium N-lauroyl sarcosinate, dipotassium alkenyl succinate; sulfate ester salts such as sodium lauryl sulfate Sulfonic acid salts such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium alkyldiphenyl ether disulfonate; phosphate esters such as polyoxyethylene alkylphenyl ether sodium phosphate; polyoxyethylene alkyl ether sodium phosphate And phosphoric acid ester salts. Of these, phosphate esters such as polyoxyethylene alkyl ether sodium phosphates are preferable from the viewpoint of ecological protection from endocrine disrupting chemicals, which have become a problem in recent years.

  Preferable specific examples of the surfactant include NC-718 manufactured by Sanyo Kasei Kogyo Co., Ltd., Phosphanol LS-529, Phosphanol RS-610NA, Phosphanol RS-620NA, Phosphorol manufactured by Toho Chemical Industry Co., Ltd. Nord RS-630NA, Phosphanol RS-640NA, Phosphanol RS-650NA, Phosphanol RS-660NA, Latemu P-0404, Latemulu P-0405, Latemulu P-0406, Latemulu P-0407 manufactured by Kao Corporation Is mentioned.

  In addition, as a method for preparing an emulsified liquid, a method in which a monomer mixture is charged in water and then a surfactant is added, a method in which a surfactant is charged in water and then a monomer mixture is charged, Examples thereof include a method of charging water after charging a surfactant into the monomer mixture. Among these, the method of charging the surfactant after charging the monomer into water and the method of charging the monomer mixture after charging the surfactant into water are the methods for obtaining the multilayer structure polymer (I). Is preferred.

Moreover, as a mixing apparatus for preparing an emulsion prepared by mixing the monomer mixture that gives the innermost layer polymer (IA) constituting the multilayer structure polymer (I) with water and a surfactant. These include a stirrer equipped with a stirring blade; various forced emulsifiers such as a homogenizer and a homomixer; a membrane emulsifier.
Further, the emulsion to be prepared may have either a W / O type or an O / W type dispersion structure, particularly an O / W type in which oil droplets of a monomer mixture are dispersed in water, and oil droplets in a dispersed phase. The diameter is preferably 100 μm or less.

  The innermost layer polymer (IA), the first intermediate layer polymer (IB), the second intermediate layer polymer (IC), and the outermost layer polymer (I) constituting the multilayer structure polymer (I) As the polymerization initiator used when forming (ID), known ones can be used. As the addition method, a method of adding to one or both of the aqueous phase and the monomer phase can be adopted. Particularly preferred polymerization initiators include peroxides, azo initiators, or redox initiators in which an oxidizing agent / reducing agent is combined. Among these, a redox initiator is more preferable, and a sulfoxylate initiator combined with ferrous sulfate, ethylenediaminetetraacetic acid disodium salt, longalite, and hydroperoxide is particularly preferable.

In particular, an emulsion prepared by mixing the monomer mixture giving the innermost layer polymer (IA) with water and a surfactant is supplied to the reactor and polymerized, and then the first intermediate layer polymer. In the method in which the monomer mixture that gives (IB), the second intermediate layer polymer (IC), and the outermost layer polymer (ID) is sequentially fed to the reactor and polymerized, After heating the aqueous solution containing monoiron, ethylenediaminetetraacetic acid disodium salt and Rongalite to the polymerization temperature, the prepared emulsion is supplied to the reactor for polymerization, and then the first containing a polymerization initiator such as peroxide. A method in which a monomer mixture giving an intermediate layer polymer (IB), a second intermediate layer polymer (IC), and an outermost layer polymer (ID) is sequentially supplied to a reactor and polymerized. The method for obtaining the multilayer structure polymer (I) is most preferable.
In addition, although superposition | polymerization temperature changes with kinds and quantity of the polymerization initiator to be used, Preferably it is 40-120 degreeC, More preferably, it is 60-95 degreeC.

<Thermoplastic polymer (II)>
The thermoplastic polymer (II) in the present invention is derived from 50 to 100% by mass of a structural unit derived from an alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms, and other vinyl monomers copolymerizable therewith. The polymer has a reduced viscosity (0.1 g of the polymer dissolved in 100 ml of chloroform and measured at 25 ° C.) of 0.1 l / min. It is a polymer which is g or less.

As the alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms used in the thermoplastic polymer (II), methyl methacrylate is most preferable.
Examples of other vinyl monomers copolymerizable with alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms used in the thermoplastic polymer (II) include methyl acrylate, ethyl acrylate, butyl acrylate, and propyl acrylate. Alkyl acrylates such as 2-ethylhexyl acrylate; alkyl methacrylates such as butyl methacrylate, propyl methacrylate, ethyl methacrylate and methyl methacrylate; aromatic vinyl compounds such as styrene, α-methyl styrene and paramethyl styrene; acrylonitrile, methacrylonitrile, etc. And vinyl cyanide compounds.

The reduced viscosity of the thermoplastic polymer (II) is 0.1 l / g or less. When the reduced viscosity exceeds 0.1 l / g, the fluidity is deteriorated, which is not preferable in terms of film moldability.
The polymerization method for obtaining the thermoplastic polymer (II) is not particularly limited, and various methods such as a commonly known suspension polymerization method and emulsion polymerization method are applied.
The thermoplastic polymer (II) is industrially available as the Mitsubishi Danyon BR series.

<Multilayer structure polymer (III)>
The multilayer polymer (III) is a multilayer polymer arranged in the order of the innermost layer polymer (III-A), the intermediate layer polymer (III-B), and the outermost layer polymer (III-C) from the center. is there.
The multilayer polymer (III) may be mixed with the thermoplastic polymer (II) as long as the film properties are not impaired.

The innermost layer polymer (III-A) is a polymer having units derived from alkyl acrylate (III-A1) having an alkyl group having 1 to 8 carbon atoms and units derived from graft crossing agent (III-A5). Yes,
The intermediate layer polymer (III-B) is a unit derived from an alkyl acrylate (III-B1) having an alkyl group having 1 to 8 carbon atoms, an alkyl methacrylate (III-B2) having an alkyl group having 1 to 4 carbon atoms. A polymer having a unit derived from and a unit derived from the graft crossing agent (III-B5) and having a composition different from that of the innermost layer polymer (III-A),
The outermost layer polymer (III-C) is a polymer having units derived from alkyl methacrylate (III-C1) having an alkyl group having 1 to 4 carbon atoms.

Furthermore, the following composition is preferable.
The innermost layer polymer (III-A) comprises 50 to 99.9% by mass of a structural unit derived from an alkyl acrylate (III-A1) having an alkyl group having 1 to 8 carbon atoms, and an alkyl group having 1 to 4 carbon atoms. 0 to 49.9 mass% of structural units derived from alkyl methacrylate (III-A2) having, 0 to 20 mass% of structural units derived from other monomer (III-A3) having a copolymerizable double bond , 0-10 mass% of structural units derived from polyfunctional monomer (III-A4) and 0.1-10 mass% of structural units derived from graft crossing agent (III-A5) ((III-A1) + (III-A2) + (III-A3) + (III-A4) + (III-A5) = 100% by mass).

  The intermediate layer polymer (III-B) contains 9.9 to 90% by mass of a structural unit derived from an alkyl acrylate (III-B1) having an alkyl group having 1 to 8 carbon atoms and an alkyl group having 1 to 4 carbon atoms. 9.9 to 90% by mass of structural unit derived from alkyl methacrylate (III-B2) having, and 0 to 20% by mass of structural unit derived from other monomer (III-B3) having a copolymerizable double bond , 0-10 mass% of structural units derived from polyfunctional monomer (III-B4) and 0.1-10 mass% of structural units derived from graft crossing agent (III-B5) ((III-B1) + (III-B2) + (III-B3) + (III-B4) + (III-B5) = 100% by mass) and is a polymer having a composition different from that of the innermost layer polymer (III-A). .

  The outermost layer polymer (III-C) is composed of 80 to 100% by mass of a structural unit derived from an alkyl methacrylate (III-C1) having an alkyl group having 1 to 4 carbon atoms and an alkyl having an alkyl group having 1 to 8 carbon atoms. 0 to 20% by mass of structural units derived from acrylate (III-C2) and 0 to 20% by mass of structural units derived from other monomer (III-C3) having a copolymerizable double bond ((III- C1) + (III-C2) + (III-C3) = 100 mass%).

  The alkyl acrylate (III-A1) having an alkyl group having 1 to 8 carbon atoms constituting the innermost layer polymer (III-A) may be either linear or branched. Specific examples thereof include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate and the like. These can be used alone or in admixture of two or more. Of these, n-butyl acrylate is preferred.

  The C1-C4 alkyl methacrylate (III-A2) constituting the innermost layer polymer (III-A) may be either linear or branched. Specific examples thereof include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate and the like. These can be used alone or in admixture of two or more. Of these, methyl methacrylate is preferred.

  Examples of the other monomer (III-A3) having a copolymerizable double bond constituting the innermost layer polymer (III-A) include lower alkoxy acrylate, cyanoethyl acrylate, acrylamide, acrylic acid, methacrylic acid. Acrylic monomers such as acids; styrene, alkyl-substituted styrene, acrylonitrile, methacrylonitrile and the like can be used.

The polyfunctional monomer (III-A4) constituting the innermost layer polymer (III-A) can be used as necessary. A polyfunctional monomer is defined as a monomer having two or more copolymerizable double bonds in one molecule. Preferable specific examples thereof include alkylene glycol dimethacrylates such as ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, and propylene glycol dimethacrylate. In addition, polyvinylbenzene such as divinylbenzene and trivinylbenzene can be used. Of these, 1,3-butylene glycol dimethacrylate is preferred.
Also, even when the polyfunctional monomer does not act at all, as long as the grafting agent is present, a fairly stable multilayer structure polymer is obtained. For example, when the hot strength or the like is strictly required, a polyfunctional monomer may be arbitrarily added depending on the purpose of addition.

The graft crossing agent (III-A5) constituting the innermost layer polymer (III-A) is defined as a monomer having two or more different copolymerizable double bonds in one molecule. Specific examples thereof include allyl, methallyl, or crotyl ester of copolymerizable α, β-unsaturated carboxylic acid or dicarboxylic acid. In particular, acrylic acid, methacrylic acid, maleic acid, or acrylic ester of fumaric acid is preferable. Of these, allyl methacrylate is preferable because of its excellent effect. In addition, triallyl cyanurate, triallyl isocyanurate and the like are also effective. In the graft crossing agent (III-A5), mainly the conjugated unsaturated bond of the ester reacts much faster than the allyl group, methallyl group, or crotyl group, and chemically bonds. A substantial portion of the allyl, methallyl, or crotyl group works effectively during the polymerization of the next layer polymer to provide a graft bond between adjacent two layers.
In addition, you may superpose | polymerize in presence of a chain transfer agent.

The content of units derived from alkyl acrylate (III-A1) having an alkyl group having 1 to 8 carbon atoms in 100% by mass of all monomer units constituting innermost layer polymer (III-A) is a multilayer structure. From the viewpoint of physical properties such as film moldability and impact resistance of the polymer (III), it is 50 to 99.9% by mass, more preferably 55 to 77.9% by mass, and most preferably 60 to 69.%. 9% by mass.
The content of units derived from alkyl methacrylate (III-A2) having an alkyl group having 1 to 4 carbon atoms in 100% by mass of all monomer units constituting innermost layer polymer (III-A) is 0 to It is 49.9 mass%, More preferably, it is 20 mass% or more, Most preferably, it is 30 mass% or more. Further, it is more preferably 44.9% by mass or less, and most preferably 39.9% by mass or less.
The unit derived from the other monomer (III-A3) having a copolymerizable double bond in 100% by mass of all monomer units constituting the innermost layer polymer (III-A) is 0-20. It is mass%, More preferably, it is 15 mass% or less.

Content of the unit derived from the polyfunctional monomer (III-A4) in 100% by mass of all monomer units constituting the innermost layer polymer (III-A) is 0 to 10% by mass, More preferably, it is 0.1 mass% or more and 6 mass% or less.
The content of units derived from the graft crossing agent (III-A5) in 100% by mass of all monomer units constituting the innermost layer polymer (III-A) is 0.1 to 10% by mass. When the content is 0.1% by mass or more, the obtained multilayer structure polymer can be formed into a film without deteriorating optical properties such as transparency. A content of 10% by mass or less is preferable because sufficient flexibility and toughness can be imparted to the multilayer structure polymer. More preferably, it is 0.5 mass% or more and 2 mass% or less.
The content of each structural unit in the innermost layer polymer (III-A) is in the above range, such as transparency and impact resistance of a colored acrylic resin film obtained by molding the multilayer structure polymer (III). From the viewpoint of physical properties of

The Tg of the innermost layer polymer (III-A) alone is an intermediate layer polymer (III-B) described later from the viewpoint of impact resistance of the colored acrylic resin film obtained by molding the multilayer structure polymer (III). It is preferably less than a single Tg. More preferably, it is less than 25 degreeC, More preferably, it is 10 degreeC or less, Most preferably, it is 0 degreeC or less.
The content of the innermost layer polymer (III-A) in the multilayer structure polymer (III) (100% by mass) depends on the transparency of the colored acrylic resin film obtained by molding the multilayer structure polymer (III). Is preferably 15 to 50% by mass, and more preferably 15 to 35% by mass. In this case, it is advantageous in terms of reflection performance when the multilayer structure polymer (III) is used as a skin material for the retroreflective sheet.

The innermost layer polymer (III-A) may be a single layer, but is preferably composed of two layers. Further, although not particularly limited, it is preferable that the monomer constitution ratios of the two layers in the innermost layer polymer (III-A) are different from each other.
When the innermost layer polymer (III-A) consists of two layers, from the viewpoint of impact resistance and transparency of the colored acrylic resin film obtained by molding the multilayer structure polymer (III), the inner layer (III- The Tg of A-1) is preferably lower than the Tg of the outer layer (III-A-2). Specifically, the Tg of the inner layer (III-A-1) is preferably less than −30 ° C. from the viewpoint of impact resistance, and the Tg of the outer layer (III-A-2) is from the viewpoint of transparency— 15 to 10 ° C is preferred.

Further, from the viewpoint of transparency, the content of the inner layer (III-A-1) in the innermost layer polymer (III-A) (100 mass%) is preferably 1 to 20 mass%, and the outer layer (III- The content of A-2) is preferably 80 to 99% by mass. An acrylic resin used as a skin material for a retroreflective sheet mainly used outdoors such as a road sign is preferably high in transparency.
As a preferable multilayer structure polymer when the innermost layer polymer (III-A) is composed of two layers, a multilayer structure polymer described in JP-B-62-19309 is exemplified.

  The alkyl acrylate (III-B1) having an alkyl group having 1 to 8 carbon atoms constituting the intermediate layer polymer (III-B) may be either linear or branched. Specific examples thereof include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate and the like. These can be used alone or in admixture of two or more. Of these, preferred are methyl acrylate and n-butyl acrylate.

  The alkyl methacrylate (III-B2) having an alkyl group having 1 to 4 carbon atoms constituting the intermediate layer polymer (III-B) may be either linear or branched. Specific examples thereof include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate and the like. These can be used alone or in admixture of two or more. Of these, methyl methacrylate is preferred.

  Examples of the other monomer (III-B3) having a copolymerizable double bond constituting the intermediate layer polymer (III-B) include lower alkoxy acrylate, cyanoethyl acrylate, acrylamide, acrylic acid, methacrylic acid, etc. Acrylic monomers, styrene, alkyl-substituted styrene, acrylonitrile, methacrylonitrile and the like can be used.

The polyfunctional monomer (III-B4) constituting the intermediate layer polymer (III-B) may be used as necessary. Preferable specific examples thereof include alkylene glycol dimethacrylates such as ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, and propylene glycol dimethacrylate. In addition, polyvinylbenzene such as divinylbenzene and trivinylbenzene can be used. Of these, 1,3-butylene glycol dimethacrylate is preferred.
Even when the polyfunctional monomer does not act at all, as long as the grafting agent is present, a fairly stable multilayer structure polymer is obtained. For example, when the hot strength or the like is strictly required, a polyfunctional monomer may be arbitrarily added depending on the purpose of addition.

Examples of the graft crossing agent (III-B5) constituting the intermediate layer polymer (III-B) include allyl, methallyl, or crotyl ester of a copolymerizable α, β-unsaturated carboxylic acid or dicarboxylic acid. It is done. In particular, acrylic acid, methacrylic acid, maleic acid, or acrylic ester of fumaric acid is preferable. Of these, allyl methacrylate is preferable because of its excellent effect. In addition, triallyl cyanurate, triallyl isocyanurate and the like are also effective. In the graft crossing agent (III-B5), the conjugated unsaturated bond of the ester mainly reacts and bonds chemically much faster than the allyl group, methallyl group, or crotyl group. A substantial portion of the allyl, methallyl, or crotyl group works effectively during the polymerization of the next layer polymer to provide a graft bond between adjacent two layers.
In addition, you may superpose | polymerize in presence of a chain transfer agent.

The content of units derived from alkyl acrylate (III-B1) having an alkyl group having 1 to 8 carbon atoms in 100% by mass of all monomer units constituting the intermediate layer polymer (III-B) is 9. 9-90% by mass. From the viewpoint of transparency of the colored acrylic resin film obtained by molding the multilayer structure polymer (III), it is more preferably 19.9% by mass or more, most preferably 29.9% by mass or more. Further, it is more preferably 60% by mass or less, and most preferably 50% by mass or less.
The content of units derived from alkyl methacrylate (III-B2) having an alkyl group having 1 to 4 carbon atoms in 100% by mass of all monomer units constituting the intermediate layer polymer (III-B) is 9. It is 9-90 mass%. From the viewpoint of transparency of the colored acrylic resin film obtained by molding the multilayer structure polymer (III), it is more preferably 39.9% by mass or more, and most preferably 49.9% by mass or more. Further, it is more preferably 80% by mass or less, and most preferably 70% by mass or less.

The content of units derived from other monomer (III-B3) having a copolymerizable double bond in 100% by mass of all monomer units constituting the intermediate layer polymer (III-B) is: It is 0-20 mass%, More preferably, it is 15 mass% or less.
The content of units derived from the polyfunctional monomer (III-B4) in 100% by mass of all monomer units constituting the intermediate layer polymer (III-B) is 0 to 10% by mass, More preferably, it is 6 mass% or less.
The content of units derived from the graft crossing agent (III-B5) in 100% by mass of all monomer units constituting the intermediate layer polymer (III-B) is 0.1 to 10% by mass. When the content is 0.1% by mass or more, the obtained multilayer structure polymer (III) can be molded without deteriorating optical properties such as transparency. A content of 10% by mass or less is preferable because sufficient flexibility and toughness can be imparted to the multilayer structure polymer (III). More preferably, it is 0.5 mass% or more and 2 mass% or less.

The composition of the intermediate layer polymer (III-B) is preferably different from the composition of the innermost layer polymer (III-A). When the compositions of these polymers are different, film properties such as impact resistance and transparency can be satisfied.
Here, “different composition” as used in the present invention means alkyl acrylate, alkyl methacrylate, other monomers having a copolymerizable double bond, a polyfunctional monomer, and a graft. The type and / or amount of crossover agent is different.

The Tg of the intermediate layer polymer (III-B) alone is preferably in the range of 25 to 100 ° C. A Tg of 25 ° C. or higher is preferred because the heat resistance, scratch resistance, and transparency of the colored acrylic resin film obtained by molding the multilayer structure polymer (III) are improved. More preferably, it is 40 degreeC or more, Most preferably, it is 50 degreeC or more. Moreover, when Tg is 100 degrees C or less, since the multilayer structure polymer with favorable film forming property is obtained, it is preferable. More preferably, it is 80 degrees C or less, Most preferably, it is 70 degrees C or less.
Further, although not particularly limited, the content of the intermediate layer polymer (III-B) in the multilayer structure polymer (III) (100% by mass) is preferably 5 to 35% by mass, more preferably. It is 20 mass% or less. If it is in this range, a function required as an intermediate layer, for example, transparency can be expressed.

  The alkyl methacrylate (III-C1) having an alkyl group having 1 to 4 carbon atoms constituting the outermost layer polymer (III-C) may be either linear or branched. Specific examples thereof include methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate and the like. These can be used alone or in admixture of two or more. Of these, methyl methacrylate is preferred.

  The alkyl acrylate (III-C2) having an alkyl group having 1 to 8 carbon atoms constituting the outermost layer polymer (III-C) may be either linear or branched. Specific examples thereof include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate and the like. These can be used alone or in admixture of two or more. Of these, preferred are methyl acrylate and n-butyl acrylate.

  Other monomers (III-C3) having a copolymerizable double bond constituting the outermost layer polymer (III-C) include lower alkoxy acrylate, cyanoethyl acrylate, acrylamide, acrylic acid, methacrylic acid, etc. Acrylic monomers, styrene, alkyl-substituted styrene, acrylonitrile, methacrylonitrile and the like can be used.

The content of units derived from alkyl methacrylate (III-C1) having an alkyl group having 1 to 4 carbon atoms in 100% by mass of all monomer units constituting outermost layer polymer (III-C) is 80 to 100% by mass, more preferably 90% by mass or more, and most preferably 93% by mass or more. Moreover, it is 99 mass% or less more preferably.
The content of units derived from alkyl acrylate (III-C2) having an alkyl group having 1 to 8 carbon atoms in 100% by mass of all monomer units constituting outermost layer polymer (III-C) is 0 to It is 20 mass%, More preferably, it is 1 mass% or more. Further, it is more preferably 10% by mass or less, and most preferably 7% by mass or less.
The content of units derived from the monomer (III-C3) having a copolymerizable double bond in 100% by mass of all monomer units constituting the outermost layer polymer (III-C) is 0 to It is 20 mass%, More preferably, it is 15 mass% or less.

  Moreover, although it does not specifically limit, a chain transfer agent is used at the time of superposition | polymerization of outermost layer polymer (III-C), and the molecular weight of outermost layer polymer (III-C) can be adjusted. This chain transfer agent is preferably selected from those usually used for radical polymerization, and specific examples thereof include alkyl mercaptans having 2 to 20 carbon atoms, mercapto acids, thiophenol, carbon tetrachloride, and the like. These can be used alone or in admixture of two or more. The content of the chain transfer agent is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the monomer ((III-C1) to (III-C3)) of the outermost layer polymer (III-C). . More preferably, it is 0.2 mass part or more, Most preferably, it is 0.4 mass part or more.

  The content of the alkyl acrylate, alkyl methacrylate, other monomer having a copolymerizable double bond, polyfunctional monomer, and graft crossing agent forming the outermost layer polymer (III-C) is as described above. The range is preferable from the viewpoint of film formability and transparency of the colored acrylic resin film obtained by molding the multilayer structure polymer (III).

The Tg of the outermost layer polymer (III-C) alone is preferably 60 ° C. or higher. The Tg of 60 ° C. or higher is preferable because a colored acrylic resin film having good film properties such as scratch resistance when the multilayer structure polymer (III) is formed into a film can be obtained. More preferably, it is 80 degreeC or more, Most preferably, it is 90 degreeC or more.
Although not particularly limited, the content of the outermost layer polymer (III-C) in the multilayer structure polymer (III) (100% by mass) is preferably 15 to 80% by mass, more preferably in terms of film properties. Is 45 to 80% by mass, most preferably 45 to 70% by mass.

As the method for producing the multilayer structure polymer (III), the sequential multi-stage polymerization method by the emulsion polymerization method is the most suitable polymerization method as in the multilayer structure polymer (I). The production of the multilayer structure polymer (III) is not particularly limited, and for example, by emulsion suspension polymerization method in which emulsion polymerization is followed by conversion to a suspension polymerization system at the time of polymerization of each outermost layer polymer. It can be carried out.
Further, although not particularly limited, when the multilayer structure polymer (III) is produced by emulsion polymerization in the same manner as the multilayer structure polymer (I), the single layer polymer (III-A) is obtained. A part or all of the monomer mixture is mixed with water and a surfactant in advance to prepare an emulsion, and after the emulsion is supplied to the reactor and polymerized, the monomer mixture constituting the remaining layers is mixed. A method in which each is sequentially supplied to the reactor and polymerized is preferred.

  The monomer mixture that gives the innermost layer polymer (III-A) was mixed with water and a surfactant in advance, and the emulsion was prepared by supplying it to the reactor and polymerizing it, and in particular dispersed in acetone. In this case, a multilayer structure polymer in which the number of particles having a diameter of 55 μm or more present in the dispersion is 0 to 50 per 100 g of the multilayer structure polymer (III) can be easily obtained. A colored acrylic resin film using the multilayer structure polymer (III) thus obtained as a raw material has a characteristic that the number of fish eyes in the film is small, and is preferable because the appearance is good.

As the surfactant used in preparing the emulsion, the same surfactants as used in preparing the emulsion with the multilayer structure polymer (I) can be used.
The method for preparing the emulsion is also preferably the same method as for the multilayer structure polymer (I).
Also, as a mixing device for preparing an emulsion prepared by mixing the monomer mixture that gives the innermost layer polymer (III-A) constituting the multilayer structure polymer (III) with water and a surfactant. Examples thereof include an apparatus used for preparing an emulsion for producing the multilayer structure polymer (I).
Further, the emulsion to be prepared may have either a W / O type or an O / W type dispersion structure, particularly an O / W type in which oil droplets of a monomer mixture are dispersed in water, and oil droplets in a dispersed phase. The diameter is preferably 100 μm or less.

  Polymerization initiator used in forming the innermost layer polymer (III-A), the intermediate layer polymer (III-B), and the outermost layer polymer (III-C) constituting the multilayer structure polymer (III) As such, a known one can be used. As the addition method, a method of adding to one or both of the aqueous phase and the monomer phase can be adopted. As a particularly preferred polymerization initiator, a peroxide, an azo initiator, or a redox initiator in which an oxidizing agent and a reducing agent are combined is used. Among these, a redox initiator is more preferable, and a sulfoxylate initiator combined with ferrous sulfate, ethylenediaminetetraacetic acid disodium salt, longalite, and hydroperoxide is particularly preferable.

In particular, an emulsion prepared by mixing a monomer mixture that gives the innermost layer polymer (III-A) with water and a surfactant is supplied to the reactor and polymerized, and then the intermediate layer polymer (III -B) and the monomer mixture that gives the outermost layer polymer (III-C) are sequentially fed to the reactor, and the method of polymerization includes ferrous sulfate, ethylenediaminetetraacetic acid disodium salt, Rongalite After raising the temperature of the aqueous solution to the polymerization temperature, the prepared emulsion is supplied to the reactor for polymerization, and then the intermediate layer polymer (III-B) containing a polymerization initiator such as peroxide, and the outermost layer polymer A method in which a monomer mixture giving (III-C) is sequentially fed to a reactor and polymerized is the most preferable method for obtaining a multilayer structure polymer (III).
In addition, although superposition | polymerization temperature changes with kinds and quantity of the polymerization initiator to be used, Preferably it is 40-120 degreeC, More preferably, it is 60-95 degreeC.

When the multilayer structure polymers (I) and (III) are obtained by emulsion polymerization as described above, a chain transfer agent, other polymerization aids and the like may be used. As the chain transfer agent, known ones can be used, and mercaptans are preferred.
The multilayer structure polymers (I) and (III) can be produced by recovering the multilayer structure polymer from the polymer latex produced by the above-described method. The method of recovering the multilayer structure polymer from the polymer latex is not particularly limited, and examples thereof include salting out or acid precipitation coagulation, spray drying, freeze drying, and the like, and the powder is recovered in powder form.

<Colorant>
Examples of the colorant include a colorant masterbatch in which a colorant component is blended using an acrylic resin as a binder, and a dry color in which a dispersant and a colorant component are blended. Here, the colorant masterbatch is a colorant masterbatch in which a colorant component is blended in a high concentration in a resin, and examples of the form include pellets and soft plate-like ones. Moreover, although resin used as a binder is not specifically limited, The thing similar to or similar to the acrylic resin used for a colored acrylic resin film is preferable. The dry color refers to a dispersible powder colorant, which is a colorant that is mechanically made into a fine powder by adding an appropriate dispersant. Preferable dispersants include calcium stearate, magnesium stearate and the like, and these can be used alone or in combination of two or more.

The colorant component is not particularly limited, and examples thereof include phthalocyanine colorants, condensed polycyclic colorants, and inorganic colorants.
Examples of the phthalocyanine colorant include CI Pigment Green 7, CI Pigment Green 36, CI Pigment Green 37, and CI Pigment Green 38.
Examples of the condensed polycyclic colorant include CI Pigment Green 47.
Examples of the inorganic colorant include CI Pigment Green 17, CI Pigment Green 19, and CI Pigment Green 50.

In particular, a phthalocyanine colorant is preferable in terms of transparency and sharpness necessary as a skin material of the retroreflective sheet, and CI Pigment Green 7 is more preferable. The CI Pigment Green 7 is industrially available as “DYMIC MBR 510” manufactured by Dainichi Seika Kogyo Co., Ltd. These colorant components can be used alone or in admixture of two or more.
Further, for the purpose of complementary colors, colorants of other colors such as quinacridone, isoindolinone, isoindoline, perylene, perinone, thioindigo, and quinophthalone may be added.

The concentration of the colorant contained in the colored acrylic resin film for the skin of the retroreflective sheeting of the present invention is such that the colored acrylic resin film is superposed on a gray-colored oily colored paper whose Munsell symbol is N5.5, and the colored acrylic resin film side is The chromaticity coordinates (x, y) in the XYZ color system when measured under the condition of the standard light D65 by the geometric condition a (45 ° illumination, vertical light reception) of illumination and light reception specified in JIS Z8722 , (0.016, 0.381), (0.185, 0.340), (0.317, 0.436) and (0.224, 0.806). For example, in the case of CI Pigment Green 7, 0.2 g / m ^{2 to} 1.5 g / m ² is a preferable range. When the density | concentration of a coloring agent is too high, transparency will fall and there exists a tendency for reflective performance important for a retroreflection sheet to fall. More preferably from ^{0.5g / m 2 ~1.0g / m 2} .

<Manufacture of colored acrylic resin film>
The method for forming the colored acrylic resin film for the retroreflective sheeting of the present invention is not particularly limited, and examples thereof include known solution casting methods, melt extrusion methods such as the T-die method, and the inflation method. Of these, the T-die method is most preferable in terms of economy.

  The thickness of the colored acrylic resin film for the retroreflective sheeting of the present invention is not particularly limited, but is 10 to 500 μm in terms of film properties. When the thickness is from 10 to 500 μm, the film has an appropriate rigidity, so that the laminate property, the secondary processability and the like become easy, and the film forming property becomes stable and the production of the film becomes easy. More preferably, they are 15 micrometers-200 micrometers, More preferably, they are 30 micrometers-200 micrometers.

  Further, the colored acrylic resin film for the skin of the retroreflective sheet of the present invention, if necessary, contains a general compounding agent such as a stabilizer, a lubricant, a processing aid, a plasticizer, an impact aid, a foaming agent, and a filling agent. Agents, antibacterial agents, antifungal agents, foaming agents, mold release agents, antistatic agents, matting agents, ultraviolet absorbers and the like. In particular, in terms of protecting the base material (retroreflective sheet), it is preferable to add an ultraviolet absorber in order to impart weather resistance. The molecular weight of the ultraviolet absorber used is preferably 300 or more, particularly preferably 400 or more. When an ultraviolet absorber having a molecular weight of less than 300 is used, it may volatilize on a transfer roll or the like when producing a film, thereby causing roll contamination. The ultraviolet absorber is not particularly limited, but a benzotriazole type having a molecular weight of 400 or more or a triazine type having a molecular weight of 400 or more can be particularly preferably used. Specific examples of the former include Tinuvin of Ciba Specialty Chemicals Co., Ltd. 234, Adeka Stub LA-31 from Asahi Denka Kogyo Co., Ltd. Specific examples of the latter include Tinuvin 1577 from Ciba Specialty Chemicals Co., Ltd.

  As a method for adding the compounding agent, a method of supplying the film forming machine for forming a film using an acrylic resin together with the acrylic resin, and a mixture in which the compounding agent is previously added to the acrylic resin are used in various kneaders. There is a method of kneading and mixing. Examples of the kneader used in the latter method include ordinary single screw extruders, twin screw extruders, Banbury mixers, roll kneaders, and the like.

<Retroreflective sheet>
The retroreflective sheet having the colored acrylic resin film for the skin of the retroreflective sheeting of the present invention on the surface is mainly used for road signs, display boards, or safety devices for the purpose of visibility.
The types of retroreflective sheets include capsule-type retroreflective sheets in which glass beads subjected to aluminum vapor deposition are embedded in the base material, and prism-type retroreflective sheets that use a prism-processed resin sheet as a reflector. The colored acrylic resin film for the retroreflective sheeting of the present invention is also used by being laminated on the surface of the retroreflective sheet.

For example, a capsule-type retroreflective sheet is manufactured as follows.
Once the upper half of the glass beads are embedded in the temporary support layer, a metal film is deposited over the gap between the lower half of the beads and the beads, and then a support film made of a thermoplastic polymer is applied in close contact with the metal film. Then, the surface is further covered with a film made of a heat-resistant resin, the temporary support layer on the opposite side is peeled off, and the colored acrylic resin film of the present invention is overlaid on the exposed upper hemisphere portion of the glass beads By using a mold having a convex mesh pattern to create a desired independent small compartment, heat press from the film side made of heat-resistant resin, etc., and heat-melt the support film and partially with the colored acrylic resin film The capsule-type retroreflective sheet is manufactured by forming the connecting wall according to the pattern and forming the independent small compartment vacancies. At this time, when the contact area between the support film and the colored acrylic resin film is large, reflection performance important as a retroreflective sheet tends to be impaired.

Hereinafter, the present invention will be described by way of examples.
Here, “part” in Examples and Comparative Examples represents “part by mass”, and “%” represents “mass%”. Abbreviations in the preparation examples are as follows.
Methyl methacrylate: MMA
Butyl acrylate: BA
Methyl acrylate: MA,
Styrene: ST,
Allyl methacrylate: AMA
1,3-butylene glycol dimethacrylate: BD,
t-butyl hydroperoxide: tBH,
Cumene hydroperoxide: CHP,
n-octyl mercaptan: n-OM.

In Examples and Comparative Examples, the evaluation of the prepared multilayer structure polymer and the measurement of various physical properties of the colored acrylic resin film were carried out by the following test methods.
1) Mass average particle diameter of multilayer polymer:
The polymer latex of the multilayer polymer obtained by emulsion polymerization was measured and determined by a dynamic light scattering method using a light scattering photometer DLS-700 manufactured by Otsuka Electronics Co., Ltd.
2) Total light transmittance of the colored acrylic resin film:
It measured based on JISK7361-1.

3) Chromaticity coordinates (x, y) and Y value of the colored acrylic resin film:
The standard color card 230 of NIPPON KENKEN CO., LTD. (Mouse color with Munsell symbol N5.5) and a colored acrylic resin film are overlaid, and the colored acrylic resin film side is the illumination and light receiving geometry specified in JIS Z8722. The measurement was performed under the condition of standard light D65 under the general condition a (45 ° illumination, vertical light reception).
4) Chromaticity coordinates (x, y) and Y value of the colored acrylic resin film on the white reflective sheet:
A colored acrylic resin film is placed on a commercially available capsule lens type retroreflective sheet (white) (trade name: Nikkalite ULS, manufactured by Nikka Polymer Co., Ltd.), and the colored acrylic resin film side is illuminated and received according to JIS Z8722. The measurement was performed under the condition of standard light D65 under the geometric condition a (45 ° illumination, vertical light reception).

5) Visibility 20 cm square commercially available capsule lens type retroreflective sheet (white) (made by Nikka Polymer Co., Ltd. (trade name: Nikkalite ULS)) was bonded to a 20 cm square colored acrylic resin film so that the four sides matched. In addition, a white white paper cut into a rectangular shape with a length of 10 cm and a width of 3 cm was pasted on a colored acrylic resin film, placed perpendicular to the ground, and the car was stopped at a distance of about 50 m from the retroreflective sheet. The retroreflective article was observed from the driver's seat, and the headlight of the automobile was used as the light for illuminating the retroreflective sheet.
(Double-circle): A rectangle can be confirmed clearly.
○: A rectangle can be confirmed.
Δ: The rectangle looks blurred.
X: A rectangle cannot be confirmed.

(Preparation Example 1)
Preparation of multilayer structure polymer (I-1):
195 parts of ion-exchanged water was put in a reaction vessel equipped with a cooler, the temperature was raised to 70 ° C., and 0.10 parts of sodium formaldehyde sulfoxylate and 0.0002 part of ferrous sulfate were added to 5 parts of ion-exchanged water. The mixture prepared by adding 0.0006 parts of EDTA was added all at once. Next, while stirring under nitrogen, a first monomer mixture and emulsifier (manufactured by Toho Chemical Industry Co., Ltd.) consisting of 2.3 parts of MMA, 2.13 parts of BA, 0.37 part of ST, 0.2 part of BD, and 0.01 part of CHP. : Phosphanol RS610NA) A mixture consisting of 1.3 parts was dropped into the reaction vessel over 8 minutes, and then the reaction was continued for 15 minutes to obtain the innermost layer polymer (I-1-A). Here, the Tg of the innermost layer polymer (I-1-A) was 13 ° C.

Subsequently, after adding a second monomer mixture consisting of 24.54 parts BA, 4.26 parts ST, 1.2 parts BD, 0.225 parts AMA and 0.03 parts CHP over 90 minutes in the polymerization vessel, The reaction was continued for 60 minutes to obtain a first intermediate layer polymer (I-1-B) containing a cross-linked elastic polymer. Here, the Tg of the first intermediate layer polymer (I-1-B) was −40 ° C.
Subsequently, a third monomer mixture of MMA 6 parts, BA 3.28 parts, ST 0.72 parts, AMA 0.15 parts, and CHP 0.02 parts was dropped into the polymerization vessel over 30 minutes, and then 60 minutes. The reaction was continued to form a second intermediate layer polymer (I-1-C).

Next, a fourth monomer mixture consisting of 52.25 parts of MMA, 2.26 parts of BA, 0.49 parts of ST, 0.193 parts of n-OM, and 0.055 parts of tBH was dropped into the polymerization vessel over 130 minutes. Then, reaction was continued for 60 minutes, outermost layer polymer (I-1-D) was formed, and the acrylic resin latex containing multilayer structure polymer (I-1) was obtained. Here, Tg of the outermost layer polymer (I-1-D) was 94 ° C. The mass average particle diameter measured after polymerization was 0.09 μm.
The polymer latex of the obtained multilayer structure polymer (I-1) is filtered using a vibration type filtration device in which a SUS mesh (average opening 62 μm) is attached to the filter medium, and then an aqueous solution containing 3 parts of calcium acetate. Salting out was carried out, and after washing and washing and drying, a powdery multilayer structure polymer (I-1) was obtained.

(Preparation Example 2)
Preparation of multilayer structure polymer (III-1):
After charging 10.8 parts of deionized water into a container equipped with a stirrer, a monomer mixture consisting of 0.3 part of MMA, 4.45 parts of BA, 0.2 part of BD, 0.05 part of AMA, and 0.025 part of CHP is charged. The mixture was stirred and mixed at room temperature. Next, 1.3 parts of an emulsifier (Toho Chemical Industries, Ltd .: Phosphanol RS610NA) was added to the vessel while stirring, and stirring was continued again for 20 minutes to prepare an emulsion.

  Next, 139.2 parts of deionized water was put into a polymerization vessel equipped with a condenser, the temperature was raised to 75 ° C., and 0.20 part of sodium formaldehyde sulfoxylate was added to 5 parts of ion-exchanged water. A mixture prepared by adding 0.0001 part of iron and 0.0003 part of EDTA was charged all at once into the polymerization vessel. Next, the emulsion was added dropwise to the polymerization vessel over 8 minutes while stirring under nitrogen, and then the reaction was continued for 15 minutes to complete the polymerization to obtain the innermost layer polymer (III-1-A1). Subsequently, a monomer mixture consisting of 9.5 parts of MMA, 14.25 parts of BA, 1.0 part of BD, and 0.25 part of AMA was dropped into the polymerization vessel over 90 minutes together with 0.016 part of CHP, and then the reaction was continued for 60 minutes. Thus, a crosslinked rubber elastic body containing a cross-linked elastic polymer (III-1-A2) was obtained. Here, the Tg of the innermost layer polymer (III-1-A1) alone was −48 ° C., and the Tg of the crosslinked elastic polymer (III-1-A2) alone was −10 ° C.

Subsequently, a monomer mixture consisting of 5.96 parts of MMA, 3.97 parts of MA and 0.07 part of AMA was dropped into the polymerization vessel over 45 minutes together with 0.0125 parts of CHP, and then the reaction was continued for 60 minutes. A coalescence (III-1-B) was formed. Here, the Tg of the intermediate layer polymer (III-1-B) alone was 60 ° C.
Next, a monomer mixture consisting of 57 parts of MMA, 3 parts of MA, 0.264 part of n-OM and 0.075 part of tBH was dropped into the polymerization vessel over 140 minutes, and then the reaction was continued for 60 minutes to obtain the outermost layer polymer (III -1-C) was formed to obtain a polymer latex of the multilayer structure polymer (III-1). Here, the Tg of the outermost layer polymer (III-1-C) alone was 99 ° C. The mass average particle diameter measured after polymerization was 0.11 μm.
The polymer latex of the obtained multilayer structure polymer (III-1) is filtered by the same method as in Preparation Example 1, then salted out in an aqueous solution containing 3.5 parts of calcium acetate, washed with water, recovered and dried. As a result, a powdery multilayer structure polymer (III-1) was obtained.

[Examples 1-3, Comparative Examples 1-3]
Adeka Stub LA-31RG (trade name) manufactured by Asahi Denka Kogyo Co., Ltd. as an ultraviolet absorber to 60 parts of the multilayer structure polymer (I-1) obtained in Preparation Example 1 and 40 parts of the thermoplastic polymer (II). Asahi Denka Kogyo Co., Ltd. ADK STAB LA-57 (trade name) as HALS (hindered amine light stabilizer), Ciba Specialty Chemicals Co., Ltd. Irganox 1076 (trade name) and colorant as antioxidant The mixture is added in the amount shown in 1 and mixed using a Henschel mixer, and the mixture is supplied to a degassing extruder (PCM-30 manufactured by Ikekai Tekko Co., Ltd.) heated to 230 ° C. and kneaded to produce pellets. Obtained.

  Here, as the thermoplastic polymer (II), Dianal BR-75 (manufactured by Mitsubishi Rayon Co., Ltd., reduced viscosity 0.057 l / g) was used. In addition, as colorants, Tokushi Co., Ltd. SD-17-A (trade name) (perylene colorant), Tokushi Co., Ltd. SD-30 (trade name) (polychlorocopper phthalocyanine colorant), ( SD-20 (trade name) (condensed azo colorant) manufactured by Tokiki Co., Ltd., DYMIC MBR 510 (trade name) manufactured by Dainichi Seika Kogyo Co., Ltd. (phthalocyanine colorant, CI Pigment Green 7), Dainichi Seika Kogyo DYMIC MBR 421 (trade name) (anthraquinone colorant), manufactured by DYMIC MBR 151 (trade name) (anthraquinone colorant), manufactured by Dainichi Chemical Industry Co., Ltd. DYMIC MBR 155 (trade name) (perylene colorant) was used.

The pellets produced by the above method were dried overnight at 80 ° C., and a cylinder temperature of 200 ° C. to 240 ° C. was measured using a 40 mmφ non-vent screw extruder (L / D = 26) equipped with a 300 mm wide T die. A colored acrylic resin film having a thickness of 85 μm was formed at a die temperature of 250 ° C. and a cooling roll temperature of 70 ° C.
Table 1 and FIG. 2 show the chromaticity coordinates (x, y), the Y value, the total light transmittance measurement results, and the visibility evaluation results in the XYZ color system of the obtained colored acrylic resin film.

[Example 4]
A 85 μm-thickness was prepared in the same manner as in Example 1 except that 100 parts of the multilayer structure polymer (III-1) obtained in Preparation Example 2 as an acrylic resin, and the compounding agent and colorant shown in Table 1 were used. A colored acrylic resin film was obtained.
Table 1 and FIG. 2 show the chromaticity coordinates (x, y), the Y value, the total light transmittance measurement results, and the visibility evaluation results in the XYZ color system of the obtained colored acrylic resin film.

[Example 5]
Except for using 80 parts of the multilayer structure polymer (III-1) obtained in Preparation Example 2 as an acrylic resin, 20 parts of the thermoplastic polymer (II), and using the compounding agents and colorants shown in Table 1. A colored acrylic resin film having a thickness of 85 μm was obtained in the same manner as in Example 1.
Table 1 and FIG. 2 show the chromaticity coordinates (x, y), the Y value, the total light transmittance measurement results, and the visibility evaluation results in the XYZ color system of the obtained colored acrylic resin film.

From the examples and comparative examples, the following became clear.
Since the retroreflective sheet using the colored acrylic resin film in Examples 1 to 5 satisfies both the standards of JIS Z9117 and ASTM D4956, the colored acrylic resin film for the retroreflective sheeting of the present invention is industrial. High utility value.
On the other hand, the retroreflective sheet using the colored acrylic resin film in Comparative Example 1 had a chromaticity coordinate (x, y) in the range described in JIS Z9117, but the Y value did not satisfy ASTM D4956. In addition, the retroreflective sheet using the colored acrylic resin film of Comparative Example 2 satisfies the Y value of ASTM D4956, but the chromaticity coordinates (x, y) in the XYZ color system are chromaticity coordinates described in JIS Z9117 ( x, y) out of range. Further, the retroreflective sheet using the colored acrylic resin film of Comparative Example 3 was not satisfactory in both chromaticity coordinates (x, y) and Y value. Those using the colored acrylic resin films of Comparative Examples 1 to 3 have low industrial utility value because the high visibility required as a retroreflective sheet cannot be obtained.

  The retroreflective sheet having the colored acrylic resin film for the skin of the retroreflective sheet of the present invention on the surface satisfies the standards of JIS Z9117 and ASTM D4956, and can be used for various displays such as road signs and construction signs. Thus, the colored acrylic resin film for the retroreflective sheeting of the present invention has a very high industrial utility value.

It is a graph which shows the range of the chromaticity coordinate (x, y) in the XYZ color system which the colored acrylic resin film for retroreflective sheet | seats of this invention should satisfy. It is a graph which shows the chromaticity coordinate (x, y) in the XYZ color system of the colored acrylic resin film in an Example and a comparative example.

Claims (5)

It is a colored acrylic resin film used as the skin material of the retroreflective sheet,
The colored acrylic resin film is superposed on a mouse-colored oil-based colored paper having a Munsell symbol of N5.5, and the colored acrylic resin film side is subjected to illumination and light receiving geometric conditions a (45 ° illumination, vertical) defined in JIS Z8722. Chromaticity coordinates (x, y) in the XYZ color system when measured under the condition of the standard light D65 by (light reception) are (0.016, 0.381), (0.185, 0.340) , (0.317, 0.436) and (0.224, 0.806), and the Y value is 2 or more.   The colored acrylic resin film for retroreflective sheeting according to claim 1, comprising any one of a phthalocyanine colorant, a condensed polycyclic colorant, and an inorganic colorant.   The total light transmittance of the colored acrylic resin film is 30% or more as measured by the method defined in JIS K7361-1, for retroreflective sheeting according to claim 1 or claim 2, Colored acrylic resin film. 4. The colored acrylic for retroreflective sheeting according to claim 1, comprising an acrylic resin composition containing the following multilayer structure polymer (I) and the following thermoplastic polymer (II): Resin film.
[Multilayer structure polymer (I)]
From the center, the multilayer structure polymer (I) is composed of the innermost layer polymer (IA), the first intermediate layer polymer (IB), the second intermediate layer polymer (IC), and the outermost layer polymer ( ID) in the order of the multilayer structure polymer,
The innermost layer polymer (IA) includes at least an alkyl methacrylate (I-A1) having an alkyl group having 4 or less carbon atoms, an alkyl acrylate (I-A2) having an alkyl group having 8 or less carbon atoms, an aromatic system A polymer obtained by polymerizing a vinyl monomer (I-A3) and a polyfunctional monomer (I-A4), having a glass transition temperature of 10 ° C. or higher;
The first intermediate layer polymer (IB) includes at least an alkyl acrylate (I-B1) having an alkyl group having 8 or less carbon atoms, an aromatic vinyl monomer (I-B2), a polyfunctional monomer A polymer having a glass transition temperature of 0 ° C. or less, obtained by polymerizing the body (I-B3) and the graft crossing agent (I-B5),
The second intermediate layer polymer (IC) is composed of alkyl methacrylate (I-C1) having an alkyl group having 4 or less carbon atoms, alkyl acrylate (I-C2) having an alkyl group having 8 or less carbon atoms, and aromatic vinyl. A polymer obtained by polymerizing the monomer (I-C3) and the graft crossing agent (I-C4),
The outermost layer polymer (ID) is composed of an alkyl methacrylate (ID1) having an alkyl group having 4 or less carbon atoms, an alkyl acrylate (ID2) having an alkyl group having 8 or less carbon atoms, and an aromatic vinyl monomer. It is a polymer having a glass transition temperature of 50 ° C. or higher obtained by polymerizing the body (I-D3).
[Thermoplastic polymer (II)]
The thermoplastic polymer (II) comprises 50 to 100% by mass of an alkyl methacrylate unit having an alkyl group having 1 to 4 carbon atoms and 0 to 50% by mass of another vinyl monomer unit copolymerizable therewith. The polymer has a reduced viscosity (0.1 g of polymer dissolved in 100 ml of chloroform and measured at 25 ° C.) of 0.1 l / g or less. The colored acrylic resin film for a retroreflective sheeting according to any one of claims 1 to 3, which comprises an acrylic resin composition containing the following multilayer structure polymer (III).
[Multilayer structure polymer (III)]
The multilayer polymer (III) is a multilayer polymer arranged in the order of the innermost layer polymer (III-A), the intermediate layer polymer (III-B), and the outermost layer polymer (III-C) from the center. Yes,
The innermost layer polymer (III-A) is a polymer having units derived from alkyl acrylate (III-A1) having an alkyl group having 1 to 8 carbon atoms and units derived from graft crossing agent (III-A5). Yes,
The intermediate layer polymer (III-B) is a unit derived from an alkyl acrylate (III-B1) having an alkyl group having 1 to 8 carbon atoms, and an alkyl methacrylate (III-B2) having an alkyl group having 1 to 4 carbon atoms. And a polymer having a composition different from that of the innermost layer polymer (III-A), and a unit derived from the graft crossing agent (III-B5).
The outermost layer polymer (III-C) is a polymer having units derived from alkyl methacrylate (III-C1) having an alkyl group having 1 to 4 carbon atoms.

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