JP5291298B2 - Phosphor paste composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluorescent paste composition excellent in screen printability and storage stability, and which can be defatted at a low temperature. <P>SOLUTION: This fluorescent paste composition comprises a (meth)acrylic resin, a fluorescent substance, an organic solvent and an imidazole-based compound, where the imidazole-based compound is expressed by chemical formula (1) or the like, wherein R<SB>1</SB>represents C<SB>n</SB>H<SB>2n+1</SB>(n is an integer of 5 or more) or C<SB>n</SB>H<SB>2n-1</SB>(n is an integer of 5 or more); R<SB>2</SB>and R<SB>3</SB>each represents H, C<SB>n</SB>H<SB>2n+1</SB>(n is an integer of 1-5) or C<SB>n</SB>H<SB>2n</SB>OH (n is an integer of 1-5); R<SB>4</SB>represents H or C<SB>n</SB>H<SB>2n+1</SB>(n is an integer of 1-5). <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

The present invention relates to a phosphor paste composition that is excellent in screen printability and storage stability and can degrease a binder resin at a low temperature.

As the binder resin used for the phosphor paste composition, a cellulose resin such as ethyl cellulose is generally used. However, in consideration of the process of dispersing phosphors, printing a pattern by screen printing, degreasing the binder resin by firing, and obtaining a phosphor layer, the cellulose-based resin is used at 500 ° C. or higher for degreasing. Must be fired. Therefore, there are problems such that a large amount of energy is required in the production process, and the baking time becomes long.

On the other hand, as a binder resin, a method using a (meth) acrylic resin that has excellent thermal decomposability and can be degreased at a low temperature has been studied. However, when a (meth) acrylic resin is used, the phosphor paste composition is very sticky, so that screen printing may cause yarn drawing by the (meth) acrylic resin to occur on the screen printing plate. Therefore, it has been difficult to obtain a phosphor paste composition suitable for screen printing.
If the blending ratio of the (meth) acrylic resin is reduced, the tackiness can be reduced, but the viscosity of the phosphor paste composition is remarkably lowered accordingly. Therefore, when the phosphor is dispersed, the phosphor may settle or aggregate, and the storage stability is not sufficient. In particular, the red phosphor is an inorganic compound such as YBO ₃ : Eu, (Y, Gd) BO ₃ : Eu, and has a higher specific gravity than other color phosphors and the like, in which the red phosphor is dispersed. The storage stability of the body paste composition was very poor.

Therefore, in order to achieve both good screen printability and storage stability, a method of blending a small amount of the molecular weight of the high molecular weight (meth) acrylic resin has been studied. However, when the molecular weight of the (meth) acrylic resin is increased, the viscosity of the phosphor paste composition can be increased even if the blending ratio of the acrylic resin is small, but the addition amount of the (meth) acrylic resin is small. Even if it exists, there existed a problem that the yarn drawing by (meth) acrylic-type resin would generate | occur | produce at the time of screen printing.

For example, Patent Document 1 discloses a method of adding a thixotropic agent such as fatty acid amide, hydrogenated castor oil, or polyamino acid. However, these thixotropic agents are all additives for increasing the viscosity of the paste composition, and it was difficult to obtain a paste composition having a viscosity suitable for screen printing in the first place.

Patent Document 2 discloses a method of adding a compound having one or more carboxyl groups such as stearic acid in order to improve the dispersibility of inorganic powders such as phosphors and glass powders. By adding a compound having at least one carboxyl group, the carboxyl group is adsorbed on the surface of the inorganic powder to neutralize the surface potential or inactivate the hydrogen bonding site, and the steric effect of the portion other than the carboxyl group By suppressing the aggregation of the inorganic powder, the dispersibility of the inorganic powder in the paste composition is improved. However, with this method, it has been difficult to maintain long-term storage stability. In particular, when a phosphor having a high specific gravity such as a red phosphor was dispersed in a paste composition having a low viscosity, the viscosity of the paste composition changed remarkably with time, and the storage stability was poor.

In Patent Document 3, in order to improve the dispersibility of the phosphor in the phosphor paste, a nonionic surface active composed of a compound containing a hydroxyalkyl group such as (bis (2-hydroxyethyl) alkylamine and a nitrogen atom). A method of adding an agent is disclosed.
However, since the phosphor paste disclosed in the example of Patent Document 3 has a viscosity of 4.4 Pa · s to 5.0 Pa · s, the phosphor immediately after being dispersed in such a phosphor paste. Shows good dispersibility, but has a problem that the phosphor settles with time.
Therefore, it has been very difficult to achieve the contradictory purpose of reducing the adhesiveness of the phosphor paste to improve the screen printability and ensuring good storage stability.
JP 2000-144124 A JP 2003-257314 A JP 2003-292947 A

An object of this invention is to provide the phosphor paste composition which is excellent in screen printability and storage stability, and can degrease binder resin at low temperature in view of the said present condition.

The present invention is a phosphor paste composition containing a (meth) acrylic resin, a phosphor, an organic solvent and an imidazole compound, wherein the imidazole compound is represented by the following chemical formula (1) or the following chemical formula (2). A phosphor paste composition.

Ｒ_１は、Ｃ_ｎＨ_２ｎ＋１（ｎは、５以上の整数）、又は、Ｃ_ｎＨ_２ｎ−１（ｎは、５以上の整数）を示し、Ｒ_２は、Ｈ、Ｃ_ｎＨ_２ｎ＋１（ｎは、１〜５の整数）、又は、Ｃ_ｎＨ_２ｎＯＨ（ｎは、１〜５の整数）を示し、Ｒ_３は、Ｈ、Ｃ_ｎＨ_２ｎ＋１（ｎは、１〜５の整数）、又は、Ｃ_ｎＨ_２ｎＯＨ（ｎは、１〜５の整数）を示し、Ｒ_４は、Ｈ、又は、Ｃ_ｎＨ_２ｎ＋１（ｎは、１〜５の整数）を示す。

R ₁ represents C _n H _{2n + 1} (n is an integer of 5 or more) or C _n H _2n-1 (n is an integer of 5 or more), R ₂ represents H, C _n H _{2n + 1} (n Is an integer of 1 to 5) or C _n H _2n OH (n is an integer of 1 to 5), R ₃ is H, C _n H _{2n + 1} (n is an integer of 1 to 5), Alternatively, C _n H _2n OH (n is an integer of 1 to 5), and R ₄ is H or C _n H _{2n + 1} (n is an integer of 1 to 5).

Ｒ_５は、Ｃ_ｎＨ_２ｎ＋１（ｎは、５以上の整数）、又は、Ｃ_ｎＨ_２ｎ−１（ｎは、５以上の整数）を示し、Ｒ_６は、Ｈ、Ｃ_ｎＨ_２ｎ＋１（ｎは、１〜５の整数）、又は、Ｃ_ｎＨ_２ｎＯＨ（ｎは、１〜５の整数）を示し、Ｒ_７は、Ｈ、Ｃ_ｎＨ_２ｎ＋１（ｎは、１〜５の整数）、又は、Ｃ_ｎＨ_２ｎＯＨ（ｎは、１〜５の整数）を示し、Ｒ_８は、Ｈ、又は、Ｃ_ｎＨ_２ｎ＋１（ｎは、１〜５の整数）を示す。
以下に本発明を詳述する。

R ₅ represents C _n H _{2n + 1} (n is an integer of 5 or more) or C _n H _2n-1 (n is an integer of 5 or more), and R ₆ represents H, C _n H _{2n + 1} (n Represents an integer of 1 to 5) or C _n H _2n OH (n is an integer of 1 to 5), R ₇ is H, C _n H _{2n + 1} (n is an integer of 1 to 5), Alternatively, C _n H _2n OH (n is an integer of 1 to 5) is shown, and R ₈ is H or C _n H _{2n + 1} (n is an integer of 1 to 5).
The present invention is described in detail below.

As a result of intensive studies, the present inventors have added a phosphor and an imidazole compound having a specific structure to a binder resin composition containing a (meth) acrylic resin and an organic solvent, so that screen printability and storage are improved. It has been found that a phosphor paste composition having excellent stability and capable of degreasing the binder resin at a low temperature can be produced, and the present invention has been completed.
Until the present inventors have discovered, imidazole compounds have been generally used as sensitizers, but as a dispersant for dispersing phosphors contained in paste compositions and inorganic powders such as glass powders. It was not used. By using an imidazole compound having a specific structure as an additive for a phosphor paste composition, the present inventors have excellent storage of a phosphor paste composition containing a phosphor, particularly a red phosphor having a high specific gravity. It has been found that stability can be exhibited.
The phosphor paste composition of the present invention is excellent in storage stability because the imidazole compound forms a structure that suppresses the precipitation of the phosphor together with the phosphor in the phosphor paste composition.

The phosphor paste composition of the present invention contains an imidazole compound represented by the following chemical formula (1) or the following chemical formula (2).

Ｒ_１は、Ｃ_ｎＨ_２ｎ＋１（ｎは、５以上の整数）、又は、Ｃ _７ Ｈ _１４ −ＣＨ＝ＣＨ−Ｃ _８ Ｈ _１７ を示し、Ｒ_２は、Ｈ、Ｃ_ｎＨ_２ｎ＋１（ｎは、１〜５の整数）、又は、Ｃ_ｎＨ_２ｎＯＨ（ｎは、１〜５の整数）を示し、Ｒ_３は、Ｈ、Ｃ_ｎＨ_２ｎ＋１（ｎは、１〜５の整数）、又は、Ｃ_ｎＨ_２ｎＯＨ（ｎは、１〜５の整数）を示し、Ｒ_４は、Ｈ、又は、Ｃ_ｎＨ_２ｎ＋１（ｎは、１〜５の整数）を示す。

R ₁ represents C _n H _{2n + 1} (n is an integer of 5 or more), or C ₇ H ₁₄ —CH═CH—C ₈ H ₁₇ , R ₂ represents H, C _n H _{2n + 1} (n is 1 to 5) or C _n H _2n OH (n is an integer of 1 to 5), R ₃ is H, C _n H _{2n + 1} (n is an integer of 1 to 5), or C _n H _2n OH (n is an integer of 1 to 5) and R ₄ is H or C _n H _{2n + 1} (n is an integer of 1 to 5).

Ｒ_５は、Ｃ_ｎＨ_２ｎ＋１（ｎは、５以上の整数）、又は、Ｃ_ｎＨ_２ｎ−１（ｎは、５以上の整数）を示し、Ｒ_６は、Ｈ、Ｃ_ｎＨ_２ｎ＋１（ｎは、１〜５の整数）、又は、Ｃ_ｎＨ_２ｎＯＨ（ｎは、１〜５の整数）を示し、Ｒ_７は、Ｈ、Ｃ_ｎＨ_２ｎ＋１（ｎは、１〜５の整数）、又は、Ｃ_ｎＨ_２ｎＯＨ（ｎは、１〜５の整数）を示し、Ｒ_８は、Ｈ、又は、Ｃ_ｎＨ_２ｎ＋１（ｎは、１〜５の整数）を示す。

R ₅ represents C _n H _{2n + 1} (n is an integer of 5 or more) or C _n H _2n-1 (n is an integer of 5 or more), and R ₆ represents H, C _n H _{2n + 1} (n Represents an integer of 1 to 5) or C _n H _2n OH (n is an integer of 1 to 5), R ₇ is H, C _n H _{2n + 1} (n is an integer of 1 to 5), Alternatively, C _n H _2n OH (n is an integer of 1 to 5) is shown, and R ₈ is H or C _n H _{2n + 1} (n is an integer of 1 to 5).

In the present specification, the imidazole compound means an imidazoline compound (dihydroimidazole) represented by the chemical formula (1) and an imidazole compound represented by the chemical formula (2).
Especially, it is preferable that the fluorescent substance paste composition of this invention contains the imidazole type compound represented by the said Chemical formula (1).

In the chemical formula (1), R ₁ is a structure represented by C _n H _{2n + 1} (n is an integer of 5 or more) or C _n H _2n-1 (n is an integer of 5 or more). R ₁ is preferably a structure represented by C _n H _{2n + 1} (n is an integer of 5 to 30) or C _n H _2n-1 (n is an integer of 5 to 30). When n is less than 5, the storage stability of the phosphor paste composition may not be obtained, and when n is more than 30, the alkyl group or alkenyl group has a long chain length. Residues may be generated.
Further, _{R 1 is, C n H 2n + 1 (} n is an integer of 10 to 20), _{or, C n H 2n-1 (} n is an integer of 10 to 20) is a structure represented by, and linear A structure is more preferable. In the chemical formula (1), when R ₁ has a linear structure, a phosphor paste composition having excellent storage stability can be obtained.

In the chemical formula (1), R ₂ is a structure represented by H, C _n H _{2n + 1} (n is an integer of 1 to 5), or C _n H _2n OH (n is an integer of 1 to 5). it is not particularly limited as long, inter alia, H, or _is preferably a C _{2 H} 4 OH.

In the chemical formula (1), R ₃ is a structure represented by H, C _n H _{2n + 1} (n is an integer of 1 to 5), or C _n H _2n OH (n is an integer of 1 to 5). Although it will not specifically limit if it is, it is preferable that it is H especially.

In the chemical formula (1), R ₄ is not particularly limited as long as it is a structure represented by H or C _n H _{2n + 1} (n is an integer of 1 to 5). .

In the chemical formula (2), R ₅ is a structure represented by C _n H _{2n + 1} (n is an integer of 5 or more) or C _n H _2n-1 (n is an integer of 5 or more). R ₅ is preferably a structure represented by C _n H _{2n + 1} (n is an integer of 5 to 30) or C _n H _2n-1 (n is an integer of 5 to 30). When n is less than 5, the storage stability of the phosphor paste composition may not be obtained, and when n is more than 30, the alkyl group or alkenyl group has a long chain length. Residues may be generated.
Further, R ₅ is a structure represented by C _n H _{2n + 1} (n is an integer of 10 to 20) or C _n H _2n-1 (n is an integer of 10 to 20), and is linear. A structure is more preferable. In the chemical formula (2), when R ₅ has a linear structure, a phosphor paste composition having excellent storage stability can be obtained.

In the chemical formula (2), R ₆ is a structure represented by H, C _n H _{2n + 1} (n is an integer of 1 to 5), or C _n H _2n OH (n is an integer of 1 to 5). it is not particularly limited as long, inter alia, H, or _is preferably a C _{2 H} 4 OH.

In the chemical formula (2), R ₇ is a structure represented by H, C _n H _{2n + 1} (n is an integer of 1 to 5), or C _n H _2n OH (n is an integer of 1 to 5). Although it will not specifically limit if it is, it is preferable that it is H especially.

In the chemical formula (2), R ₈ is not particularly limited as long as it is a structure represented by H or C _n H _{2n + 1} (n is an integer of 1 to 5). .

Specific examples of the imidazole compound are not particularly limited, and examples of the imidazole compound represented by the chemical formula (1) include 2- (8-heptadecenyl) -2-imidazoline-1-ethanol (R ₁ : _{C 7 H 14 -CH = CH-} C 8 H 17, R 2: C 2 H 4 OH, R 3: H, R 4: H), 2- undecyl imidazoline _{(R 1: C 11 H 23} , R 2 : H, R ₃ : H, R ₄ : H), 2-heptadecylimidazoline (R ₁ : C ₁₇ H ₃₅ , R ₂ : H, R ₃ : H, R ₄ : H) and the like. Among these, when 2- (8-heptadecenyl) -2-imidazoline-1-ethanol is used, a phosphor paste composition having excellent storage stability can be obtained, and therefore, it can be suitably used.

Examples of the imidazole compound represented by the chemical formula (2) include 2- (8-heptadecenyl) -2-imidazole-1-ethanol (R ₅ : C ₇ H ₁₄ —CH═CH—C ₈ H ₁₇ , R _6. : C ₂ H ₄ OH, R ₇ : H, R ₈ : H), 2-undecylimidazole (R ₅ : C ₁₁ H ₂₃ , R ₆ : H, R ₇ : H, R ₈ : H), 2- Heptadecyl imidazole (R ₅ : C ₁₇ H ₃₅ , R ₆ : H, R ₇ : H, R ₈ : H) and the like can be mentioned.

Although it does not specifically limit as content of the said imidazole type compound in the fluorescent substance paste composition of this invention, A preferable minimum is 0.01 weight% and a preferable upper limit is 10 weight%. When the content of the imidazole compound is less than 0.01% by weight, the storage stability of the phosphor paste composition may not be sufficiently obtained. When the content exceeds 10% by weight, it may be fired at a low temperature. Residues may be generated. A more preferable lower limit of the content of the imidazole compound is 0.1% by weight, and a more preferable upper limit is 5% by weight.

The phosphor paste composition of the present invention contains a (meth) acrylic resin as a binder resin.
The (meth) acrylic resin is not particularly limited as long as it is a (meth) acrylic resin that can be degreased at a low temperature (400 ° C. or lower). For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl ( (Meth) acrylate, n-butyl (meth) acrylate, tert-butyl (meth) acrylate, isobutyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isobornyl (meth) acrylate, n-stearyl ( Homopolymers of (meth) acrylate monomers such as (meth) acrylate and benzyl (meth) acrylate, and the above (meth) acrylate monomers, polypropylene oxide, polymethylethylene oxide, polyethylethylene oxide, polytri Chiren'okishido, and it can be used a copolymer of having a polyoxyalkylene structure of polytetramethylene oxide and the like (meth) acrylate monomer. Here, for example, (meth) acrylate means acrylate or methacrylate.
Especially, since the viscosity of the phosphor paste composition suitable for screen printability can be obtained while reducing the content of (meth) acrylic resin, the glass transition temperature (Tg) is high and degreasing is performed at a low temperature. It is preferable to contain a methyl methacrylate monomer which can be used as a polymer component, and polymethyl methacrylate which is a homopolymer of a methyl methacrylate monomer is particularly preferable.

The (meth) acrylic resin preferably has at least one hydrogen bonding functional group only at the molecular end. When the hydrogen bonding functional group is present in the molecular side chain of the (meth) acrylic resin, the (meth) acrylic resin and the organic solvent are compatible with each other, so that an appropriate phase separation state described later is difficult to be expressed, and the phosphor paste composition The viscosity of the product will decrease. When the content of the (meth) acrylic resin is increased in order to obtain a viscosity suitable for screen printing, problems such as the occurrence of yarn drawing during screen printing occur. On the other hand, the hydrogen bonding functional group is not present in the molecular side chain of the (meth) acrylic resin, but is present only at the molecular end, so that the (meth) acrylic resin and the organic solvent are not compatible with each other and appropriate phase separation Even when the content of (micro) separation resin is small and the content of (meth) acrylic resin is small, the adhesive strength of the phosphor paste composition is lowered with sufficient viscosity. The screen printability is improved without the occurrence of yarn pulling.

The hydrogen bonding functional group is not particularly limited, and examples thereof include a hydroxyl group, a carboxyl group, and an amino group. Of these, a hydroxyl group and a carboxyl group are preferred for the reason that there is little influence on the thermal decomposability of the (meth) acrylic resin.

The preferable lower limit of the number average molecular weight in terms of polystyrene of the (meth) acrylic resin is 5000, and the preferable upper limit is 50000. If the number average molecular weight is less than 5,000, the (meth) acrylic resin and the organic solvent cannot exhibit an appropriate phase separation (microphase separation), and the viscosity required for screen printing may not be obtained. If it exceeds 50000, the (meth) acrylic resin and the organic solvent are completely phase separated, and the adhesive strength of the phosphor paste composition of the present invention is increased, which may cause problems in screen printability. is there. The upper limit with the more preferable number average molecular weight of the said (meth) acrylic resin is 40000, and a more preferable upper limit is 30000. In particular, the (meth) acrylic resin having a number average molecular weight of 5,000 to 30,000 is preferable because a clear print pattern can be obtained during screen printing.
In the conventional phosphor paste composition, a (meth) acrylic resin having a relatively high molecular weight has been used in order to maintain a viscosity capable of screen printing. In contrast, in the phosphor paste composition of the present invention, a (meth) acrylic resin having a number average molecular weight in the range of 5000 to 50000 is obtained by appropriately phase-separating (microphase separation) the phosphor paste composition. In addition to being able to exhibit good screen printability even when used, it has become possible to reduce the residue of (meth) acrylic resin after firing.
In addition, the measurement of the number average molecular weight by polystyrene conversion can be obtained by performing GPC measurement using, for example, a column LF-804 manufactured by SHOKO as a column.

When the (meth) acrylic resin after the polymerization reaction is used without being purified as the binder resin used in the phosphor paste composition of the present invention, a monomer or oligomer that is a low molecular weight component may be used as the phosphor paste composition. It is preferable that it is not contained in. When a monomer, oligomer, or the like, which is a low molecular weight component, is contained in the phosphor paste composition, the monomer, oligomer, or the like may act as a plasticizer and reduce the viscosity of the phosphor paste composition.

The molecular weight distribution (weight average molecular weight / number average molecular weight = Mw / Mn) of the (meth) acrylic resin is preferably 3 or less, more preferably 2.5 or less.
If the molecular weight distribution exceeds 3, monomers or oligomers that are low molecular weight components act as plasticizers, and if the phosphor paste composition does not have sufficient viscosity, or if it contains a high molecular weight component ( In some cases, the yarn may be drawn by a (meth) acrylic resin, which may cause a problem during screen printing.

Although it does not specifically limit as content of the (meth) acrylic resin in the fluorescent substance paste composition of this invention, A preferable minimum is 5 weight% and a preferable upper limit is 25 weight%. When the content of the (meth) acrylic resin is less than 5% by weight, the phosphor paste composition may not have sufficient viscosity and storage stability may not be sufficiently obtained, and exceeds 25% by weight. If the phosphor paste composition is too viscous and sticky, problems may occur during screen printing.

As a method for introducing a hydrogen bonding functional group only at the molecular end of the (meth) acrylic resin, for example, the above-mentioned (meth) acrylate monomer is used as a free radical under a chain transfer agent having a hydrogen bonding functional group. Under a polymerization method, a living radical polymerization method, an iniferter polymerization method, an anionic polymerization method, a living anion polymerization method or the like, a (co) polymerization method or a polymerization initiator having a hydrogen bonding functional group And (co) polymerization of the above-mentioned (meth) acrylate monomer by a conventionally known method such as a free radical polymerization method, a living radical polymerization method, an iniferter polymerization method, an anion polymerization method, or a living anion polymerization method. These methods may be used in combination.
Moreover, it can be confirmed by, for example, ¹³ C-NMR that a hydrogen-bonding functional group is introduced only at the molecular end of the (meth) acrylic resin.

The chain transfer agent is not particularly limited as long as it is a chain transfer agent having the hydrogen bonding functional group. For example, a mercaptopropanediol having a hydroxyl group as a hydrogen bonding functional group, a carboxyl group as a hydrogen bonding functional group. Examples thereof include thioglycerol, mercaptosuccinic acid, mercaptoacetic acid, aminoethanethiol having an amino group as a hydrogen bonding functional group, and the like.

The polymerization initiator is not particularly limited as long as it is a polymerization initiator having the hydrogen bonding functional group. For example, P-menthane hydroperoxide (“Permenta H” manufactured by NOF Corporation), diisopropylbenzene hydroperoxide (Japan) (Oil & Fats Company "Park Mill P"), 1,2,3,3-tetramethylbutyl hydroperoxide (Nippon Yushi Co., Ltd. "Perocta H"), cumene hydroperoxide (Nippon Yushi Co., Ltd. "Park Mill H-80"), t -Butyl hydroperoxide ("Perbutyl H-69" manufactured by NOF Corporation), cyclohexanone peroxide ("Perhexa H" manufactured by NOF Corporation), 1,1,3,3-tetramethylbutyl hydroperoxide, t-butylhydro Peroxide, t-amyl hydroperoxide, Disuccinic acid perox ide (paroyl SA) and the like.

The phosphor paste composition of the present invention contains a phosphor.
The phosphor is not particularly limited, and examples thereof include CRT phosphors, lamp phosphors, PDP phosphors, X-ray phosphors, phosphorescent phosphors, and the like used for various purposes. Specifically, for example, as a red phosphor, Y ₂ O ₃ : Eu, Y ₂ O ₂ S: Eu, YBO ₃ : Eu, (Y, Gd) BO ₃ : Eu, Y (P, V) O ₄ Eu, GdBO ₃ : Eu, Y ₂ SiO ₅ : Eu, Y ₃ Al ₅ O ₁₂ : Eu, ScBO ₃ : Eu, LuBO ₃ : Eu, Zn ₃ (PO ₄ ) ₂ : Mn, etc .; as a green phosphor Sr ₆ Si ₃ O ₃ Cl ₄ : Eu, ZnS: Cu, Al, LaPO ₄ : Ce, Tb, CaMgSi ₂ O ₆ : Eu, (Ba, Sr, Mg) O.aAl ₂ O ₃ Mn, (Y, Gd) BO ₃ : Tb, Zn ₂ SiO ₄ : Mn, BaAl ₁₂ O ₁₉ : Mn, BaMgAl ₁₀ O ₁₇ : Mn, BaMgAl ₁₀ O ₁₇ : Mn, Eu, BaMgAl ₁₄ O ₂₃ : Mn, CaAl ₁₂ O _{19 : Mn, SrAl 12 O 19:} Mn, YBO 3: Tb, LuBO 3: Tb, GdBO 3: Tb, Gd 2 O 2 S: Tb, ScBO 3: Tb, Sr 4 Si 3 O 8 Cl 4: Eu and the like; As the blue phosphor, ZnS: Ag, Al, (SrCaBaMg) ₅ (PO ₄ ) ₃ Cl: Eu, BaMgAl ₁₀ O ₁₇ : Eu, BaMgAl ₁₄ O ₂₃ : Eu, Y ₂ SiO ₅ : Ce, CaWO ₄ , CaWO ₄ : Pb, (Ca, Sr) MgSi ₂ O ₆ : Eu, (Ca, Sr) Mg ₂ Si ₂ O ₇ : Eu, (Ca, Sr) ₂ MgSi ₂ O ₇ : Eu, etc .; , Sr ₄ Al ₁₄ O ₂₅ : Eu, Dy, etc .; Examples of white phosphors include Ca ₁₀ (PO ₄ ) ₆ FCl: Sb, Mn.

The phosphor paste composition of the present invention can also be suitably used when it contains the red phosphor.
In general, since the red phosphor has a higher specific gravity than other phosphors, when the phosphor paste composition contains a red phosphor, the red phosphor easily settles and the storage stability is not sufficient. . On the other hand, in the phosphor paste composition of the present invention, even when the red phosphor is contained, the red phosphor does not settle and is excellent in storage stability. This is considered because the imidazole compound forms a structure that suppresses the precipitation of the red phosphor in the phosphor paste composition of the present invention.

Although it does not specifically limit as content of the said fluorescent substance, The binder resin composition which consists of components (components other than fluorescent substance and an imidazole type compound), such as a (meth) acryl resin and an organic solvent among the fluorescent substance paste compositions of this invention. A preferable lower limit is 30 parts by weight and a preferable upper limit is 85 parts by weight with respect to 100 parts by weight of the product. When the content of the phosphor is less than 30 parts by weight, the resulting phosphor paste composition may have a low viscosity and storage stability may not be sufficient. When the content of the phosphor exceeds 85 parts by weight, it may be difficult to disperse the phosphor in the obtained phosphor paste composition.

The phosphor paste composition of the present invention contains an organic solvent.
The organic solvent preferably has at least one hydroxyl group or acetoxy group in the molecule. As a result, appropriate phase separation (microphase separation) between the (meth) acrylic resin and the organic solvent is facilitated, and the blending ratio of the (meth) acrylic resin is reduced while maintaining a viscosity suitable for screen printing. Becomes easy and can be degreased at low temperatures.

The said organic solvent has a preferable minimum of a boiling point of 170 degreeC, and a preferable upper limit of 280 degreeC. When the boiling point of the organic solvent is less than 170 ° C., the organic solvent volatilizes during screen printing, and screen printing may be difficult. When the boiling point exceeds 280 ° C., the phosphor paste composition of the present invention is reduced. It may not be possible to fire at low temperatures. A more preferable lower limit of the boiling point of the organic solvent is 200 ° C., and a more preferable upper limit is 250 ° C.

The organic solvent is not particularly limited. For example, ethylene glycol ethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoisobutyl ether, trimethylpentanediol monoisobutyrate. , Diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, terpineol, texanol, isophorone, butyl lactate, dioctyl phthalate, dioctyl adipate, benzyl alcohol, phenylpropylene glycol, cresol and the like.
Of these, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoisobutyl ether, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, terpineol, and texanol are preferable, and among them, diethylene glycol monoisobutyl ether, diethylene glycol monobutyl ether, diethylene glycol monobutyl ether Butyl ether acetate, terpineol, and texanol are particularly suitable, and diethylene glycol monobutyl ether, diethylene glycol monobutyl ether acetate, terpineol, and texanol are particularly preferably used.
In addition, these organic solvents may be used independently and 2 or more types may be used together.

The phosphor paste composition of the present invention has a preferred lower limit of 8 Pa · s and a preferred upper limit of 40 Pa · s when measured at 23 ° C. using a B-type viscometer with the probe rotation speed set to 10 rpm. . When the viscosity is less than 8 Pa · s, the viscosity of the phosphor paste composition becomes low, the phosphor may settle, and a problem may occur in storage stability. When the viscosity exceeds 40 Pa · s, the adhesiveness of the phosphor paste composition increases, and yarn spinning may occur during screen printing.

The phosphor paste composition of the present invention is excellent in screen printability.
When the conventional phosphor paste composition is screen-printed, problems such as fading of the print pattern or inability to print have occurred. On the other hand, since the phosphor paste composition of the present invention is excellent in the storage stability of the phosphor, a clean print pattern can be obtained even after long-term storage.

The method for producing the phosphor paste composition of the present invention is not particularly limited and includes conventionally known methods. For example, the components are mixed using various mixers such as a ball mill, a blender mill, and a three roll. Methods and the like. Specifically, for example, the (meth) acrylic resin and the organic solvent are mixed using a mixer to prepare a binder resin composition, and then the phosphor and the imidazole compound are added to the binder resin composition. The method of adding and mixing using a mixer etc. is mentioned.

The binder resin composition has a preferred lower limit of viscosity of 2 Pa · s and a preferred upper limit of 20 Pa · s when measured at 23 ° C. using a B-type viscometer with the probe rotation speed set to 10 rpm. When the viscosity is less than 2 Pa · s, the viscosity of the obtained phosphor paste composition becomes low, the phosphor may settle, and a problem may occur in storage stability. When the viscosity exceeds 20 Pa · s, it may be difficult to sufficiently disperse the phosphor in the obtained phosphor paste composition.

ADVANTAGE OF THE INVENTION According to this invention, the phosphor paste composition which is excellent in screen printing property and storage stability and can degrease binder resin at low temperature can be provided.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Example 1
In a 2 L separable flask equipped with a stirrer, a cooler, a thermometer, a hot water bath and a nitrogen gas inlet, 100 parts by weight of methyl methacrylate (MMA), mercaptopropanediol as a chain transfer agent, and 100% by weight of diethylene glycol monobutyl ether as an organic solvent The monomer mixture was obtained.

The obtained monomer mixture was bubbled with nitrogen gas for 20 minutes to remove dissolved oxygen, and then the temperature inside the separable flask system was replaced with nitrogen gas and heated until the hot water bath boiled with stirring. An ethyl acetate solution of a polymerization initiator was added, and further an ethyl acetate solution of a polymerization initiator was added several times during the polymerization.

Seven hours after the start of polymerization, the polymerization was terminated by cooling to room temperature. Thereby, a diethylene glycol monobutyl ether solution of polymethyl methacrylate (PMMA) having a hydroxyl group at the terminal was obtained. The obtained (meth) acrylic resin was analyzed by gel permeation chromatography using a column LF-804 manufactured by SHOKO as a column, and the number average molecular weight in terms of polystyrene was as shown in Table 1.
To the diethylene glycol monobutyl ether solution of polymethyl methacrylate thus obtained, diethylene glycol monobutyl ether is further added so as to have the composition ratio shown in Table 1, and dispersed with a high-speed disperser to produce a binder resin composition. did.

With respect to the obtained binder resin composition, 2- (8-heptadecenyl) -2-imidazoline-1-ethanol is represented as an imidazole compound, and (Y, Gd) BO ₃ : Eu (red phosphor) is represented as a phosphor. The mixture was added so as to have the composition ratio described in 1, sufficiently kneaded using a high-speed stirrer, and kneaded with a three-roll mill until it reached a smooth state to prepare a phosphor paste composition.

(Examples 2-6, Comparative Examples 1-6)
A binder resin composition and a phosphor paste composition were prepared in the same manner as in Example 1 except that each component was adjusted to have the composition ratio described in Table 1, Table 2, or Table 3.

(Evaluation)
The phosphor paste compositions prepared in Examples 1 to 6 and Comparative Examples 1 to 6 were evaluated by the following methods.
The results are shown in Table 4.

(1) Storage stability (Viscosity change rate (%))
The phosphor paste composition immediately after dispersing the phosphor is put in a 250 ml polyethylene container, and the fluorescence is measured using a B-type viscometer (“DVII + Pro” manufactured by BROOK FILED) at a temperature of 23 ° C. and a rotation speed of 10 rpm. The viscosity η ^A _{10 rpm} (Pa · s) of the body paste composition was measured. Thereafter, the phosphor paste composition placed in a polyethylene container is stored for one month in an environment of a temperature of 23 ° C. and a humidity of 50%, and again using a B-type viscometer under the conditions of a temperature of 23 ° C. and a rotation speed of 10 rpm. Then, the viscosity η ^B _{10 rpm} (Pa · s) of the stored phosphor paste composition was measured, and the viscosity change rate (%) was calculated.
Viscosity change rate (%) was calculated by the following formula.
Viscosity change rate (%) = [(η ^A _{10 rpm−} η ^B _{10 rpm} ) / η ^A _{10 rpm} ] × 100

(2) Storage stability (presence or absence of precipitate)
The phosphor paste composition immediately after the phosphor was dispersed was placed in a 250 ml polyethylene container, and it was visually observed whether or not a precipitate was present at the bottom of the container. Thereafter, the phosphor paste composition placed in a polyethylene container was stored for one month in an environment of a temperature of 23 ° C. and a humidity of 50%, and then it was visually observed again whether a precipitate was present at the bottom of the container.
The following criteria were used to evaluate whether sediment was present at the bottom of the container.
○: No precipitate was observed at the bottom of the container.
X: A precipitate was observed at the bottom of the container.

(3) The phosphor paste composition immediately after the screen-printing phosphor was dispersed was put in a 250 ml polyethylene container and stored for 1 month in an environment of a temperature of 23 ° C. and a humidity of 50%. Next, screen printing was performed using the stored phosphor paste composition in an environment of a temperature of 23 ° C. and a humidity of 50%.
For screen printing, a screen printing machine ("MT-320TV" manufactured by Microtech Co., Ltd.), screen plate making ("SX230 ° B" manufactured by Tokyo Process Service Co., Ltd. (emulsion 20 μm, screen frame 320 mm x 320 mm)), printing substrate (soda glass) 150 mm × 150 mm, thickness 15 mm), and screen printing was performed under the conditions of the following screen printer.
Gap: 2.0mm
Squeegee speed: 50 mm / s
Scraper speed: 50mm / s
Squeegee pressure: 0.25 MPa
Scraper pressure: 0.17 MPa
Back pressure: 0.10 MPa

FIG. 1 shows an aspect of screen printing. A print pattern 1 shown in FIG. 1 is a print pattern formed in the horizontal direction with respect to the moving direction of the squeegee. A print pattern 2 shown in FIG. 1 is a print pattern formed in a 45 ° oblique direction with respect to the moving direction of the squeegee.
With respect to the print pattern 1 and the print pattern 2 shown in FIG. 1, screen printability was evaluated according to the following criteria.
○: No fading was observed in the print pattern.
X: The print pattern was faint or could not be printed.

ADVANTAGE OF THE INVENTION According to this invention, the phosphor paste composition which is excellent in screen printing property and storage stability and can degrease binder resin at low temperature can be provided.

It is a schematic diagram which shows an example of the aspect of screen printing.

Claims (5)

A phosphor paste composition containing a (meth) acrylic resin, a phosphor, an organic solvent, and an imidazole compound,
The imidazole compound is represented by the following chemical formula (1) or the following chemical formula (2).

R ₁ represents C _n H _{2n + 1} (n is an integer of 5 or more), or C ₇ H ₁₄ —CH═CH—C ₈ H ₁₇ ,
R ₂ represents H, C _n H _{2n + 1} (n is an integer of 1 to 5), or C _n H _2n OH (n is an integer of 1 to 5),
R ₃ represents H, C _n H _{2n + 1} (n is an integer of 1 to 5), or C _n H _2n OH (n is an integer of 1 to 5),
R ₄ represents H or C _n H _{2n + 1} (n is an integer of 1 to 5).

R ₅ represents C _n H _{2n + 1} (n is an integer of 5 or more) or C _n H _2n-1 (n is an integer of 5 or more),
R ₆ represents H, C _n H _{2n + 1} (n is an integer of 1 to 5), or C _n H _2n OH (n is an integer of 1 to 5),
R ₇ represents H, C _n H _{2n + 1} (n is an integer of 1 to 5), or C _n H _2n OH (n is an integer of 1 to 5),
R ₈ represents H or C _n H _{2n + 1} (n is an integer of 1 to 5). The phosphor paste composition according to claim 1, wherein the (meth) acrylic resin is polymethyl methacrylate. The phosphor paste composition according to claim 1 or 2, wherein the phosphor is a red phosphor. 4. The phosphor paste composition according to claim 1, wherein the viscosity is 8 to 40 Pa · s measured at 23 ° C. using a B-type viscometer with the probe rotation speed set to 10 rpm. object. The phosphor paste composition according to claim 1, 2, 3 or 4, wherein the organic solvent has at least one hydroxyl group or acetoxy group in the molecule and has a boiling point of 170 to 280 ° C.

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