TWI591673B - Method of forming an insulating film - Google Patents

Description

Method for forming insulating film

The present invention relates to a method of forming an insulating film.

As a screen display device that replaces a large and heavy cathode ray tube, a so-called flat panel display that is light and thin is attracting attention. Although liquid crystal displays are actively being developed as flat panel displays, liquid crystal displays have the disadvantage of narrow viewing angles. In addition, a plasma display device of a self-luminous discharge type display or a screen display device using an electronic release device has a wide viewing angle compared with a liquid crystal display, and can meet the requirements of large screen and high definition. Is rising.

The plasma display has a structure in which the front panel and the back panel are opposed to each other at a fixed interval and hermetically sealed by a sealing glass. The display electrode and the address electrode are opposed to each other in a discharge space provided between the front panel and the back panel. Then, plasma discharge occurs between the electrodes, and ultraviolet rays are generated by a gas such as Xe-Ne encapsulated in the discharge space, and the particles are passed through the phosphor in the discharge space for display.

In the front panel, the display electrode including the conductive metal particles is formed into a strip shape, and the insulating film for covering the electrodes to maintain the plasma discharge is formed into a solid film shape. Further, the back surface plate is formed with an address electrode, and an insulating film for coating the same is formed in the same manner as the front panel. Furthermore, the insulating film on the back panel is specified in order to suppress the plasma discharge width in a fixed range. The display is performed in the unit cell while ensuring a uniform discharge space to form a separator, and a phosphor layer for emitting light is formed in the unit cell.

As an existing method of forming the insulating film as described above, it is known that an insulating paste containing glass particles is applied onto a substrate by a screen printing method or an overall coating method, and dried, and the organic component is thermally decomposed and removed, and the glass particles are sintered. The method (Patent Document 1). Moreover, the insulating film of the front panel needs to be manipulated to have the characteristics of the insulating film and the electrode having high withstand voltage and high visible light transmittance, the surface roughness of the insulating film, and the state of the bubble in the insulating film. Techniques such as characteristics (Patent Documents 2 and 3).

In addition, as a method of forming an insulating film which does not cause cracking and peeling from the substrate, and simultaneous sintering of the separator and the insulating film without impairing the formation of the separator, development using a thermal polymerization-containing polymerization is being developed. A method of insulating paste of an agent and a thermosetting component (Patent Document 4).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. Hei 11-246236

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2005-38824

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2008-60064

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2001-26477

However, the conventional method for forming an insulating film can obtain a table. An insulating film having a small surface roughness, that is, an insulating film having high microscopic smoothness, and at the same time, on the surface of the insulating film, irregularities on the substrate due to electrodes or the like are also observed, and an insulating film having high overall smoothness cannot be obtained. . The problem of the unevenness of the entire insulating film is caused by the shrinkage of the coating film at the same shrinkage ratio on the convex portion (for example, the electrode forming portion) of the substrate and the concave portion (for example, the electrode non-forming portion) of the substrate when the coating film is heated. Even if a thermoplastic polymer such as a highly stretchable compound having a urethane skeleton and an acrylic resin is used to improve the flexibility and toughness of the insulating film, if the degree of unevenness is large, the insulating film is cracked, so the present state is eager. Looking forward to alternative technology.

In order to solve the above problems, the inventors of the present invention have repeated the results of intensive studies and found the following inventions (1) to (9).

(1) A method of forming an insulating film, comprising: applying a coating film containing a thermal polymerization initiator, a thermosetting component, and glass particles to a substrate having irregularities to obtain a coating film; and heating the coating film A semi-hardening step of obtaining a semi-hardened film having a hardening rate of 30 to 95%; and a sintering step of heating the semi-cured film to obtain an insulating film.

(2) The method for forming an insulating film according to (1) above, wherein the heating temperature of the semi-hardening step is T ₁ and the 10-hour half-life temperature of the thermal polymerization initiator is T ₁₀ , which satisfies T ₁₀ <T ₁ ≦T ₁₀ +30 °C relationship.

(3) The method for forming an insulating film according to (2) above, wherein the coated film after the heating in the semi-hardening step is cooled at a temperature T ₂ lower than the T ₁ to obtain the semi-cured film.

(4) The method for forming an insulating film according to (3) above, wherein the T _{2 is} lower than the T ₁₀ .

(5) The method of forming an insulating film described in any one of the through (4) above (2), wherein the holding time of the above-described half-life of less than ₁ T T ₁ of the above-mentioned thermal polymerization initiator.

(6) The method for forming an insulating film according to any one of the above (1) to (5), wherein the thermal polymerization initiator is a compound which is activated to be an active radical species, and has a 10-hour half-life temperature T ₁₀ is 60~110 °C.

(7) The method for forming an insulating film according to any one of the above (1), wherein the thermosetting component contains a compound having three or more carbon-carbon unsaturated double bonds.

(8) The method for forming an insulating film according to any one of the above (1) to (7) wherein the organic solid component of the insulating paste has a carbon-carbon unsaturated double bond density of 3 to 9 mmol/g.

(9) A plasma display device comprising: a substrate; a plurality of electrode pairs disposed on the upper surface of the substrate; and a plasma display element covering the insulating film of the electrode, wherein the substrate is vertically oriented with respect to the upper surface of the substrate When the maximum thickness of the insulating film is H1 and the minimum thickness of the insulating film in the vertical direction with respect to the upper surface of the substrate is H2, the relationship of 0.2 [μm] ≦ H1 - H2 ≦ 1.0 [μm] is satisfied.

According to the present invention, it is possible to provide an insulating film having a characteristic of a so-called high withstand voltage and high visible light transmittance, and having no cracks or smooth surface irregularities even when the substrate has irregularities due to an electrode or the like.

[Formation of the Invention]

Hereinafter, the preferred embodiments of the present invention are described in detail, but the present invention is not limited thereto.

A method of forming an insulating film according to the present invention, comprising: applying a coating film containing a thermal polymerization initiator, a thermosetting component, and glass particles to a substrate having irregularities to obtain a coating film; and heating the coating film And obtaining a semi-hardening step of a semi-hardened film having a hardening rate of 30 to 95%; and a sintering step of heating the semi-cured film to obtain an insulating film.

The insulating paste used in the method for forming an insulating film of the present invention needs to contain a thermal polymerization initiator, a thermosetting component, and glass particles, but may contain other components such as a thermoplastic polymer, a plasticizer, a solvent, a dispersant, and a uniformity. A paint or filler. As a method of producing the insulating paste, a method in which the materials are stirred in advance and then kneaded by a disperser such as a roll mill, followed by filtration and defoaming under reduced pressure can be exemplified.

As a thermal polymerization initiator, it is preferable that the active radical species can be heated to have a 10-hour half-life temperature T ₁₀ of 40 to 130 ° C, and the stability of the insulating paste is ensured and the activity of the radical is sufficient for 10 hours. The half-life temperature T _{10 is} preferably from 60 to 110 °C.

The 10-hour half-life temperature T ₁₀ (hereinafter, referred to as "T ₁₀ ") means a time required until one half of the thermal polymerization initiator decomposes and remains half of the amount, that is, a temperature at which the half-life is 10 hours. When T ₁₀ is 40° C. or more, the stability of the insulating paste can be maintained, and at 130° C. or lower, the activity at the heating temperature can be sufficiently exhibited. When the T ₁₀ is less than 40 ℃ tackifier is caused after a long time stability can not be maintained like insulating paste, if a high surface tension, it is difficult to form a coating film having high smoothness. Further, if T _{10 is} more than 130 ° C, the heating temperature of the high semi-hardening step must be set, and the surface of the obtained semi-cured film is uneven due to the rapid evaporation of the solvent contained in the insulating paste.

As the thermal polymerization initiator, an organic peroxide or an azo compound is preferred.

As the organic peroxide having a T ₁₀ of 40 to 130 ° C, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl) peroxydicarbonate, peroxygen can be exemplified. Di(methoxyisopropyl) dicarbonate, di(2-ethylhexyl)peroxydicarbonate, di(3-methyl-3-methoxybutyl)peroxydicarbonate, peroxy neodecanoic acid Tertiary butyl ester, 2,4-dichlorobenzhydryl peroxide, tert-butyl peroxytrimethylacetate, 3,5,5-trimethylhexyl peroxide, octanyl peroxide, cerium peroxide Base, peroxidized lauryl sulfhydryl, peroxy succinic acid, ethoxylated oxime, peroxy(2-ethylhexanoic acid) tertiary butyl ester, meta-toluene formazan, benzammonium peroxide, peroxygen Tert-butyl butyl butyrate, 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis(tri-butylperoxy) Cyclohexane, peroxybutyl succinate, butyl laurate, butyl peroxy 3,3,5-trimethylhexanoate, peroxycyclohexane, Tert-butyl butyl isopropyl carbonate, 2,5-dimethyl-2,5-bis(benzhydrylperoxy)hexane, 2,2-bis(tertiary butylperoxy)octane Peracetic acid tri Butyl ester, 2,2-bis(tertiary butylperoxy)butane, butyl peroxybenzoate, n-butyl 4,4-bis(tertiary butylperoxy)pentanoate, two Di-tertiary butyl peroxyisophthalate, butanone peroxide, α,α'-bis(tri-butylperoxyisopropyl)benzene, dicumyl peroxide, 2,5-dimethyl -2,5-di(tertiary butylperoxy)hexane, tertiary butyl peroxy cumene, dicumyl hydroperoxide or di-tertiary butyl peroxide.

As an azo compound having a T ₁₀ of 40 to 130 ° C, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2-azobisisobutyronitrile, 2,2' can be exemplified. - azobis(2-methylbutyronitrile), 1,1-azobis(cyclohexan-1-carbonitrile), 1-[(1-cyano-1-methylethyl)azo]formamidine Amine (2-(aminomercaptoazo)isobutyronitrile), 2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyl Benzylamine}, 2,2'-azobis{2-methyl-N-[2-(1-hydroxybutyl)]propanamine}, 2,2'-azobis[2- Methyl-N-(2-hydroxyethyl)propanamide], 2,2'-azobis[N-(2-propenyl)-2-methylpropanamide], 2,2'- Azobis(N-butyl-methylpropionamide), 2,2'-azobis(N-cyclohexyl-2-methylpropionamide), 2,2'-azobis[2- (5-methyl-2-imidazolin-2-yl)propane] dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride or 2,2'-Azobis[2-(5-methyl-2-imidazolin-2-yl)propane]disulfate dihydrate.

The ratio of the thermal polymerization initiator is preferably from 1 to 15% by mass, preferably from 7 to 12% by mass, based on the thermosetting component to be described later. When the thermal polymerization initiator is less than 1% by mass, irregularities are generated on the surface of the semi-cured film. In addition, when the thermal polymerization initiator is more than 15% by mass, precipitation or cracking of the thermal polymerization initiator on the surface of the semi-cured film is likely to occur.

As the thermosetting component, a compound having a carbon-carbon unsaturated double bond (hereinafter referred to as "compound C") is preferred. As the compound C, a compound having a vinyl group, a propylene group, a (meth) acrylate group or an acrylamide group can be exemplified, but various kinds of compounds are being developed to be able to be based on reactivity, solubility, double bond equivalent, and the like. Appropriately It is preferred to select a compound having a (meth) acrylate group, that is, a (meth) acrylate compound.

Among the (meth) acrylate compounds, a semi-cured film which is capable of forming a three-dimensional network structure, which has a high reaction rate by using a living radical species generated by a thermal polymerization initiator as a starting point, and which is capable of forming a three-dimensional network structure. From the viewpoint of maintaining the effect of smoothing the smoothness of the semi-cured film, a (meth) acrylate compound having three or more functional groups is preferred. Examples of the (meth) acrylate compound having three or more functional groups include trimethylolpropane tri(meth) acrylate, ethoxylated trimethylolpropane tri(meth) acrylate, and propoxylated three. Hydroxymethylpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propoxylated glycerol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, two - trimethylolpropane tetra(meth)acrylate, dipentaerythritol hydroxypenta(meth)acrylate, dipentaerythritol pentaacrylate or dipentaerythritol hexaacrylate or such rings Oxylkane metabolites.

Further, a polymer having a carbon-carbon unsaturated double bond in its side chain is also preferred as the compound having a carbon-carbon unsaturated double bond. As such polymers, for example, a main chain having an acrylic structure, a urethane structure, a polyester structure or an epoxy structure, and a side chain having a carbon-carbon double bond can be exemplified.

When the compound C is used as the thermosetting component, the carbon-carbon unsaturated double bond density (hereinafter referred to as "Y") of the organic solid component in the insulating paste is preferably 3 to 9 mmol/g, preferably 3.5. ~7mmol/g. When Y is less than 3 mmol/g, the effect of maintaining the smoothness of the coating film is small, and unevenness is generated on the surface of the insulating film. Further, if Y is more than 9 mmol/g, the sintering shrinkage rate of the film of the sintering step becomes too large, and the partial film floats from the substrate. Start.

In addition, the organic solid component in the insulating paste refers to an organic component which is an organic component contained in the insulating paste, and the solvent is removed.

Y is calculated by the following formula (2) using the double bond equivalent Z calculated by the following formula (1). When a different plurality of compounds C are used in combination, Y is calculated by the total number of individual carbon-carbon unsaturated double bond densities.

Z(g/mol)=M/N‧‧‧(1)

M: molecular weight of compound C

N: the number of carbon-carbon unsaturated double bonds of compound C

Y(mol/g)=Σ(O/Z)‧‧‧(2)

O: ratio of the compound C of the organic solid component (% by mass) / 100

The volume ratio of the compound C to all the inorganic components in the insulating paste is preferably from 0.5 to 1.5, more preferably from 0.6 to 1.2. If the volume ratio of the compound C is less than 0.5, irregularities are generated on the surface of the insulating film. Further, if the volume ratio of the compound C is more than 1.5, the partial film floats from the substrate. In addition, all the inorganic components in the insulating paste may refer to all inorganic compounds contained in the insulating paste, and also include glass particles.

The insulating paste used in the method for forming an insulating film of the present invention preferably contains a thermoplastic polymer. As the thermoplastic polymer, a cellulose resin or an acrylic resin can be exemplified. The proportion of the thermoplastic polymer is preferably from 1 to 40 parts by mass, more preferably from 2 to 20 parts by mass, per 100 parts by mass of the glass particles. As the cellulose resin, ethyl cellulose, hydroxyethyl cellulose, methyl cellulose or carboxymethyl cellulose can be exemplified. However, ethyl cellulose is preferred because the dispersibility of the glass particles is good, and the coating property of the insulating paste in the screen printing or the overall coating method can be imparted, and the sintering step is easily and thermally decomposed and volatilized. As the acrylic resin, a monomer or copolymer of acrylic acid or alkyl acrylate or methacrylic acid or alkyl methacrylate is preferred. More specifically, for example, polyacrylic acid, polymethacrylic acid, polymethyl acrylate, polyethyl acrylate, polymethyl methacrylate, polyethyl methacrylate, polypropyl methacrylate, polymethacrylic acid A monomer or copolymer of butyl ester or polyhexyl methacrylate is preferred.

The insulating paste used in the method for forming an insulating film of the present invention may contain a solvent. The term "solvent" as used herein means a liquid component which volatilizes by 60% by mass or more in the heating temperature and heating time of the semi-hardening step. The solvent is used for the purpose of adjusting the viscosity of the insulating paste and obtaining better fluidity for the selected coating method, but it is relatively easy to volatilize at the heating temperature and heating time of the semi-hardening step. As the solvent, terpineol, diethylene glycol butyl ether acetate, diethylene glycol monophenyl ether acetate, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate can be exemplified. , butyl carbitol acetate, butyl carbitol, γ-butyrolactone, butyl acesulfame acetate, celecoxib acetate, butyl acesulfame, butyl methoxyacetate or n-butyl acetate or a mixture thereof. The proportion of the solvent in the insulating paste is preferably 20 to 60% by mass, preferably 20 to 40% by mass.

The insulating paste used in the method for forming an insulating film of the present invention may contain a plasticizer. The plasticizer is used for the purpose of improving the smoothness of the semi-hardened film. The plasticizer is preferably sufficiently higher than the boiling point of the heating temperature T ₁ of the semi-hardening step, and is substantially non-volatile in the semi-hardening step. As the plasticizer, butyl benzyl phthalate, dioctyl phthalate, diisooctyl phthalate, dinonyl phthalate, dibutyl phthalate or phthalate can be exemplified. Isodecyl methacrylate or a mixture of these. The proportion of the plasticizer in the insulating paste is preferably 0.5 to 10% by mass, preferably 1 to 5% by mass. When the proportion of the plasticizer is less than 0.5% by mass, a portion where the solvent is volatilized locally is generated, and the smoothness of the semi-cured film is easily deteriorated. In addition, when the proportion of the plasticizer is more than 10% by mass, the compatibility with the thermoplastic polymer or the thermosetting component is insufficient, and the smoothness of the semi-cured film is easily deteriorated.

As the glass particles contained in the insulating paste used in the method for forming an insulating film of the present invention, for example, a component selected from the group consisting of ZnO ₂ , B ₂ O ₃ , Bi ₂ O ₃ , SiO ₂ and PbO can be used. Although it is a glass particle which is a main component, it is preferable to use a lead-free glass particle by the use of the environmental load material. The term "main component" as used herein means a component which contains the most in mass %. In particular, ZnO-B ₂ O ₃ -based lead-free glass particles containing TiO ₂ and further selected from the group consisting of CuO, MoO ₃ , CeO ₂ , MnO ₂ and CoO, represented by the following composition ratio It is preferable that the yellowing due to the reaction with the electrode is not easily caused, the transparency is good, and the sinterability is good at a temperature of 600 ° C or lower.

(Composition ratio of ZnO-B ₂ O ₃ based lead-free glass particles (better composition ratio in parentheses))

ZnO: 25 to 55 mass% (28 to 50 mass%)

B ₂ O ₃ : 10 to 40% by mass (15 to 35 mass%)

ZnO+B ₂ O ₃ : 46~80% by mass (49~75% by mass)

SiO ₂ : 1 to 20% by mass (3 to 18% by mass)

Bi ₂ O ₃ : 0 to 50% by mass (1 to 30% by mass)

Li ₂ O: 0 to 8 mass% (0 to 5 mass%)

Na ₂ O: 0 to 10% by mass (0 to 7% by mass)

K ₂ O: 0 to 15% by mass (0 to 13% by mass)

Li ₂ O+Na ₂ O+K ₂ O: 0 to 15% by mass (0.1 to 13% by mass)

MgO: 0 to 20% by mass (0 to 17% by mass)

CaO: 0 to 20% by mass (0 to 17% by mass)

SrO: 0 to 20% by mass (0 to 17% by mass)

BaO: 0 to 20% by mass (0 to 17% by mass)

MgO+CaO+SrO+BaO: 0~25% by mass (0~20% by mass)

TiO ₂ : 0.3 to 10% by mass (0.5 to 8 mass%)

CuO: 0.01 to 0.3% by mass (0.05 to 2.5% by mass)

CuO+MoO ₃ +CeO ₂ +MnO ₂ +CoO: 0.01 to 6% by mass (0.01 to 5% by mass)

In order to reduce bubbles in the insulating film, the glass particles are preferably used in an average particle diameter D ₅₀ of 3.0 μm or less and a maximum particle diameter D _max of 20 μm or less.

The proportion of the other components in the insulating paste is preferably 0 to 3% by mass of the dispersant, 0 to 1% by mass of the leveling agent, and 0 to 3% by mass of the filler.

The coating step of the method for forming an insulating film of the present invention refers to a step of applying an insulating paste to a substrate having irregularities to obtain a coating film. The term "substrate" as used herein refers to a plate material containing glass or ceramics.

According to the present invention, an insulating film having high smoothness can be formed regardless of the unevenness on the substrate. The method for forming the insulating film of the present invention is The unevenness on the substrate is preferably in the range of 1 to 20 μm in height and 1 to 1000 μm in pitch, and is preferably used in the range of 1 to 7 μm in height and 50 to 500 μm in pitch.

As a method of applying an insulating paste to a substrate, an integral coating method or a screen printing method using a bar coater, a roll coater, a slit die coater, or a knife coater can be used, but the number of times of application is small. In other words, the overall coating method is preferred, and from the viewpoint of less unevenness in the plane and high coating film thickness accuracy, an overall coating method using a slit die coater is preferred. Further, if the viscosity of the insulating paste or the like is appropriate, a coating film having high overall smoothness can be obtained.

The thickness of the coating film obtained in the coating step can be appropriately determined in consideration of the shrinkage of the subsequent step, etc., but in order to ensure insulation and smoothness, it is preferable to adjust the thickness of the insulating film obtained by the sintering step to 5 to 100 μm. It is preferably adjusted to 20 to 60 μm. Further, when an electrode is formed on the substrate, the thickness of the coating film of the convex portion (electrode forming portion) of the substrate is individually adjusted to 30 to 150 μm, and the thickness of the coating film of the concave portion (electrode non-forming portion) of the substrate is adjusted to 31~ 170 μm is preferred.

The semi-hardening step of the method for forming an insulating film of the present invention means that the coating film obtained by the coating step is heated at a temperature T ₁ and then cooled to a temperature T ₂ to obtain a semi-cured film having a hardening rate of 30 to 95%. step.

By heating the coating film at a temperature T ₁ (hereinafter referred to as "T ₁ ") and performing thermal curing, the viscosity of the coating film can be increased to maintain the flat shape of the coating film, and unevenness on the surface of the semi-cured film can be suppressed.

As to a method of heating T _1, the coating film can be uniformly heated, the drying machine in order to better IR irradiation. Yet, it is harmless to the coating film into pre-warmed to T ₁ and the start of the dryer is heated, or the coated film is harmless at room temperature into a dryer after the start of heating, raising the temperature stepwise or continuously. Although T ₁ is suitably determined depending on the kind of the thermal polymerization initiator, the step management is preferably in the range of 40 ° C < T ₁ ≦ 140 ° C, preferably 60 ° C < T ₁ ≦ 120 ° C.

T ₁ and the above T ₁₀ are preferably in a relationship satisfying the following formula (3), and preferably satisfy the relationship of the following formula (4). Further, when a plurality of kinds of thermal polymerization initiators having different half-lives of 10 hours are used in combination, T ₁₀ can be calculated by weighted averaging.

T ₁₀ <T ₁ ≦T ₁₀ +30°C‧‧‧(3)

T ₁₀ <T ₁ ≦T ₁₀ +10°C‧‧‧(4)

When T _{1 is} less than T ₁₀ , thermal curing of the polymerization initiator and the thermosetting component cannot be promoted, and irregularities are generated on the surface of the semi-cured film. Further, when T _{1 is} larger than T ₁₀ + 30 ° C, the decomposition rate of the thermal polymerization initiator becomes excessively fast, and it is difficult to control not only the hardening rate of the semi-cured film but also the degree of hardening in the semi-cured film.

The heating temperature is from the time of reaching T ₁ until the start of cooling, that is, the holding time of T ₁ (hereinafter referred to as "t ₁ "), and the half life of the thermal polymerization initiator smaller than T ₁ is preferably 0.5~, preferably 0.5~ 3 hours. When t ₁ is a half life or more, irregularities or cracks are likely to occur. Yet, even when the heating temperature exceeds Buyer than T _1, if the range of T ₁ ± 5 ℃, also can be regarded as an error range of t ₁ are continued.

T ₁ is possible by heating the coating film at the start, cooled below the temperature T ₁ T ₂ (hereinafter referred to as "T _2") to obtain hardening of 30 to 95% of a semi-cured film. By cooling to T ₂ , the addition of active radical species can be inhibited from occurring. Further, if the sintering step is performed by omitting the cooling of T ₂ , the thermal curing progresses out of control, and cracks are formed on the surface of the obtained insulating film.

In order to sufficiently suppress the occurrence of the addition of the active radical species, the T ₂ system is preferably lower than T ₁₀ . If the cooling rate or time can be appropriately set, the hardening rate of the obtained semi-cured film may be in the range of 30 to 95%, but the hardening rate of the obtained semi-cured film is preferably in the range of 50 to 93%. . The hardening rate X of the semi-hardened film is formed by using an insulating paste which has been applied to the substrate in the coating step to form a mold coating film, which is heated and cooled under the same conditions (temperature and time) as the semi-hardening step, and is calculated and obtained. The hardening rate of the model semi-hardened film is determined. More specifically, a model coating film having a thickness of 100 μm × a length of 1 mm × a width of 1 mm is formed on a heating table of ATR (Attenuated Total Reflectance) crystal, and the model is obtained by in-situ measurement by infrared spectroscopic analysis. The peak intensity (hereinafter referred to as "S") of the C=C stretching vibration of the carbon-carbon unsaturated double bond derived from the individual thermosetting component of the coating film, the model semi-cured film, and the fully cured film can be used The X calculated by the following formula (5) determines the hardening rate of the semi-hardened film.

X(%)=(S ₀ -S _x )/(S ₀ -S ₁₀₀ )×100‧‧‧ Equation (5)

S ₀ : model coated film S

S ₁₀₀ : S of fully cured film

S _x : model semi-hardened film S

The term "completely cured film" as used herein refers to a film obtained by heating a mold coating film under normal pressure at a time of 1000 times the half-life of the thermal polymerization initiator at T ₁₀ + 80 ° C.

When the hardening rate of the semi-hardened film is less than 30%, the effect of suppressing unevenness is insufficient because the effect of maintaining the flat shape by thermal hardening is small. In addition, when the hardening rate of the semi-hardened film is more than 95%, the semi-cured film loses toughness, and cracks are generated in a portion where the thickness of the film such as the electrode forming portion in the subsequent sintering step is small due to the variation in local shrinkage stress.

Further, the amount of the solvent remaining in the semi-cured film which is not volatilized after the semi-hardening step is preferably from 0 to 40% by volume, preferably from 0 to 20% by volume, based on the total volume of the semi-cured film. If the amount of the residual solvent is more than 40% by volume, irregularities are formed on the surface of the insulating film.

The sintering step of the method for forming an insulating film of the present invention refers to a step of obtaining a semi-cured film obtained by the semi-hardening step to obtain an insulating film. The sintering step is roughly classified into a pre-heating process of thermally decomposing and removing the organic component in the semi-hardened film, and a sintering process with the sintered glass particles or the like.

The heating for thermal decomposition and removal of the organic component in the semi-hardened film is preferably carried out at 300 to 450 ° C for 5 to 30 minutes. When the heating temperature is less than 300 ° C, the removal of the organic component is insufficient, and the bubbles in the insulating film are increased. Further, when the heating temperature is more than 450 ° C, the volume shrinkage due to thermal decomposition and removal of the organic component is caused, and the insulating film is likely to be cracked.

The heating system for sintering the glass particles or the like is preferably carried out at 500 to 600 ° C for 5 to 15 minutes, preferably at a temperature equal to or higher than the softening point of the glass particles for 5 to 15 minutes. If the heating temperature for sintering is too high than the softening point of the glass particles, and the heating time becomes too long, the substrate is deformed, and the components such as the substrate or the electrode and the components in the insulating film are Carry out the reaction.

In the sintering step of the method for forming an insulating film of the present invention, when an electrode is formed on a substrate, the sintering shrinkage rate of the semi-hardened film of the convex portion (electrode forming portion) of the substrate is significantly higher than that of the concave portion of the substrate (electrode non-forming portion) The semi-cured film has a sintering shrinkage ratio, so that an insulating film having high overall smoothness can be obtained. The difference in the sintering shrinkage ratio of the portion is based on the mass transfer from the convex portion (electrode forming portion) of the substrate to the concave portion (electrode non-forming portion) of the substrate. Although the principle is not clear, it is considered that in the process of thermally decomposing and removing the organic component, once the organic component is softened or liquefied, the viscosity is largely reduced, and on the other hand, it is presumed to be intentionally left by semi-hardening. The unreacted thermosetting component is thermally cured, and the surface tension can be increased by thickening the entire film, and the flat shape of the semi-cured film can be maintained and directly transferred to the sintering process.

As described above, the method for forming an insulating film of the present invention is preferably formed by forming an insulating film on a substrate having electrodes or the like formed on the substrate.

A plasma display device of the present invention is a plasma display device including a substrate, a plurality of electrode pairs disposed on the substrate, and an insulating film covering the electrode, wherein the above is perpendicular to the upper surface of the substrate When the maximum thickness of the insulating film is H1 and the minimum thickness of the insulating film in the direction perpendicular to the upper surface of the substrate is H2, the relationship of 0.2 [μm] ≦ H1 - H2 ≦ 1.0 [μm] is satisfied. Further, it is preferable that H1 and H2 satisfy the relationship of 0.2 [μm] ≦ H1 - H2 ≦ 0.5 [μm].

When the plasma display device of the present invention is a plasma display front panel (hereinafter referred to as a "front panel"), if H1-H2 is 0.2 μm or more, the production efficiency is improved by the improvement of exhaust efficiency, and By good The priming discharge reduces power consumption. In addition, when the thickness is 1.0 μm or less, the gap with the back surface plate becomes uniform and small, and the discharge can be stably stabilized by greatly reducing the cross-talk phenomenon, so that the reliability is remarkably improved. Further, since the interference phenomenon is greatly reduced, the distance between adjacent electrodes is reduced, and the opening portion is widened, whereby the brightness can be remarkably improved.

When the plasma display device of the present invention is a plasma display back panel (hereinafter referred to as "back panel"), if H1-H2 is 0.2 μm or more, it is possible to suppress the separator formed on the insulating film from falling. In addition, when it is 1.0 μm or less, it is possible to prevent cracking of the insulating film by suppressing stress concentration in the insulating film due to excessive unevenness.

The smoothness of the surface of the insulating film can be evaluated by a laser microscope. More specifically, a portion on the electrode on the surface of the insulating film (approximately the central portion in the width direction of the electrode) and none of the surface of the insulating film can be measured at a magnification of 50 times at a plane 100 using a laser microscope (VK-9700; manufactured by Keyence Corporation). The height difference of the electrode portions (approximately the central portion between adjacent electrodes) was quantitatively evaluated by calculating the average value thereof. This average value can be directly used as the value of the above "H1-H2". Further, when cracks were generated, no cracks were measured, and when cracks were generated in total, measurement was impossible.

The defect on the surface of the insulating film can be evaluated by observing the number of cracks or bubbles by a laser microscope (magnification: 50 times).

An example of the manufacturing method of the front panel is shown below. First, indium tin oxide (hereinafter referred to as "ITO") is sputtered on a glass substrate, and a transparent electrode is formed by photo-etching. Printing a photosensitive black for forming a black electrode on a glass substrate on which a transparent electrode has been formed A coating film was formed by coloring the electrode paste, and a highly conductive photosensitive white electrode paste was applied to form a two-layer coating film. The obtained two-layer coating film was exposed and developed together to form an elongated bus bar electrode pattern. The front panel can be obtained by sintering the obtained bus bar electrode pattern to form an insulating film covering the bus bar electrode pattern. Further, as needed, it is also possible to form a protective film mainly composed of a black strip or a black matrix or MgO for enhancing contrast.

As the glass substrate, heat-resistant glass (PP8 or PP9 (manufactured by Nippon Electric Glass Co., Ltd.) or PD200 (manufactured by Asahi Glass Co., Ltd.)) for soda glass or a plasma display panel can be exemplified. The paste for forming a black electrode is mainly composed of an organic binder, a black pigment, and a conductive powder. However, when a pattern is formed by photolithography, a photosensitive organic compound can be used as the organic binder. As the black pigment, a metal oxide is preferred. As the metal oxide, although titanium black or a metal oxide of copper, iron, manganese or cobalt can be exemplified, a metal oxide of cobalt is preferred because of little fading after sintering. As the conductive powder, a metal powder or a metal oxide powder can be exemplified. As the metal powder, gold, silver, copper or nickel can be exemplified.

Since the black electrode is high in electrical resistance, the above-described manufacturing method is coated with a white electrode paste having a lower electrical resistivity. As the white electrode paste, silver may be used as a main component. The film thickness of the black electrode after sintering and the white electrode after sintering is preferably 1 to 7 μm. Further, the line width of the two electrodes after sintering is preferably 20 to 100 μm, and the pitch is preferably 1 to 1000 μm. Further, the thickness of the insulating film is preferably 5 to 100 μm. As a method of forming the insulating film, a method of forming the insulating film of the present invention is preferred.

An example of a method of manufacturing a back panel is shown below. First, an elongated electrode pattern is formed on a glass substrate, and an insulating film covering the same is formed. A photosensitive separator paste for forming a separator is applied onto a glass substrate on which an electrode pattern and an insulating film have been formed to form a coating film, which is dried and then exposed and developed to form a separator pattern such as a lattice. The obtained electrode pattern, insulating film, and separator pattern are sintered at a temperature of 570 to 620 ° C for 10 to 60 minutes, and a back sheet can be obtained by forming a phosphor.

As a method of forming the elongated electrode pattern, a photosensitive paste method can be exemplified. As a method of forming the insulating film, a method of forming the insulating film of the present invention is preferred.

As a coating method of the photosensitive spacer paste, a bar coater, a roll coater, a slit die coater, a knife coater, or screen printing can be exemplified. The thickness of the coating film of the photosensitive separator paste can be determined in consideration of the height of the desired separator and the shrinkage rate due to sintering. In order to secure a sufficient discharge space to form brightness, the height of the separator is preferably 100 μm or more.

The exposure of the coating film of the photosensitive separator paste is usually a method of passing through a photomask, but it is also possible to draw directly by laser light or the like. As the exposure device, a stepper exposure machine or a proximity exposure machine can be exemplified. As the active light source, ultraviolet rays, ultraviolet rays, electron beams, X-rays or laser light can be exemplified, but ultraviolet rays are preferred. As the light source of the ultraviolet light, a low pressure mercury lamp, a high pressure mercury lamp, an ultra high pressure mercury lamp, a halogen lamp or a germicidal lamp can be exemplified, but an ultrahigh pressure mercury lamp is preferred. Although the exposure conditions vary depending on the thickness of the coating film of the photosensitive separator paste, an ultrahigh pressure mercury lamp having a power of 1 to 100 mW/cm ² is usually used for exposure for 0.01 to 30 minutes. Further, as a method of development, a dipping method, a spraying method, or a painting method can be exemplified.

As a method of forming the phosphor, a photolithography method, a dispenser method, or a screen printing method can be exemplified. The thickness of the phosphor is preferably 10 to 30 μm, preferably 15 to 25 μm.

[Examples]

The present invention will be described in detail below with reference to the examples and comparative examples, but the invention is not limited thereto.

(Example 1)

1 part by mass of 1,1-azobis(cyclohexan-1-carbonitrile), 10 parts by mass of trimethylolpropane propylene oxide-modified triacrylate, 2 parts by mass of ethyl cellulose, 30 parts by stirring Parts by mass of terpineol, 6 parts by mass of butyl carbitol acetate, 1 part by mass of isodecyl phthalate, 50 parts by mass of glass particles A, 0.2 parts by mass of dispersant, and 0.1 part by mass After the leveling agent is mixed, it is kneaded by a roll mill and then subjected to filtration and defoaming under reduced pressure to obtain an insulating paste a.

(Glass particle A: mass ratio of composition ratio, ZnO 35.8 mass%, B ₂ O ₃ 37.1 mass%, SiO ₂ 12.0 mass%, K ₂ O 12.6 mass%, Al ₂ O ₃ 1.4 mass%, TiO ₂ 0.8 mass %, CuO 0.3% by mass, average particle diameter D ₅₀ of 2.0 μm, maximum particle diameter D _max of 10.0 μm, softening point of 584 ° C, and thermal expansion coefficient of 73.7×10 ^-7 /°C)

A glass substrate (PD200; manufactured by Asahi Glass Co., Ltd.) having a strip-shaped electrode pattern having a line width of 40 μm, a film thickness of 5 μm, and a pitch of 200 μm was formed, and the insulating paste a was applied as a solid by a slit die coater. In the form of a coating film a having a film thickness of 105 μm (coating step). also In the film thickness of the coating film a, the film thickness of the concave portion (electrode non-formed portion) of the insulating film a finally obtained is 30 μm, and is determined in consideration of the shrinkage ratio of the insulating paste a.

The coating film a was heated at 95 ° C (T ₁ ) using an IR irradiation type dryer, cooling was started from 95 ° C and then 30 minutes (t ₁ ), and cooled at 25 ° C (T ₂ ) to obtain a semi-hardened film a1. (Semi-hardening step). Also, the cooling time at T ₂ was 2 hours. Further, the special model coating film a was formed on a heating table made of diamond ATR crystals, heated at 95 ° C, cooled from 95 ° C and then 30 minutes, and cooled at 25 ° C for 2 hours. The hardening rate of the model semi-hardened film a1 is determined as the hardening rate of the semi-hardened film a1.

The semi-hardened film a1 was heated at 380 ° C for 10 minutes to thermally decompose and remove the organic component in the semi-hardened film a1. Thereafter, the film was further heated at 600 ° C for 10 minutes to sinter glass particles or the like to obtain an insulating film a1 (sintering step).

(Example 2)

The same operation as in Example 1 was carried out except that t ₁ was 60 minutes, and the insulating film a2 was obtained through the semi-hardened film a2. Further, when determining the rate of hardening of the semi-cured film a2, and t ₁ of the model with the coating film will also a2 heating time was changed to 60 minutes 60 minutes. That is, a special model coating film a is formed on a heating table made of diamond ATR crystals, heated at 95 ° C, cooled from 95 ° C and then 60 minutes, and cooled at 25 ° C for 2 hours. The hardening rate of the semi-hardened film a2 determines the hardening rate of the semi-hardened film a2. In the following Examples 3 to 27 and Comparative Examples 1 to 5, similarly, when T ₁ or t ₁ of the heating conditions of the semi-hardening step was changed, the heating conditions of the mold coating film were also changed in accordance with the change.

(Example 3)

1.2 parts by mass of 1,1-azobis(cyclohexan-1-carbonitrile), 12 parts by mass of di-trimethylolpropane tetraacrylate, 2 parts by mass of ethylcellulose, and 28 parts by mass were stirred in advance. Terpineol, 6 parts by mass of butyl carbitol acetate, 1 part by mass of isodecyl phthalate, 50 parts by mass of glass particles A, 0.2 parts by mass of a dispersing agent, and 0.1 parts by mass of a uniform coating After the agent, the mixture was kneaded by a roll mill and then subjected to filtration and defoaming under reduced pressure to obtain an insulating paste b.

The same operation as in Example 1 was carried out except that the insulating paste b and t _{1 were used} for 60 minutes to obtain an insulating film b.

(Example 4)

0.4 parts by mass of 1,1-azobis(cyclohexan-1-carbonitrile), 3.9 parts by mass of dipentaerythritol pentaacrylate, 6.6 parts by mass of dipentaerythritol hexaacrylate, and 2 masses were previously stirred. Ethylcellulose, 28 parts by mass of terpineol, 6 parts by mass of butyl carbitol acetate, 1 part by mass of isodecyl phthalate, 50 parts by mass of glass particles A, 0.2 mass After dispersing agent and 0.1 part by mass of the leveling agent, the mixture was kneaded by a roll mill, filtered, and defoamed under reduced pressure to obtain an insulating paste c.

The same operation as in Example 1 was carried out except that the insulating paste c and t _{1 were used} for 60 minutes to obtain an insulating film c.

(Example 5)

1 part by mass of 1,1-azobis(cyclohexan-1-carbonitrile), 10 parts by mass of diethylene glycol dimethacrylate, 2 parts by mass of ethyl cellulose, and 30 parts by mass of hydrazine were previously stirred. Sterol, 6 parts by mass of butyl carbitol acetate, 1 part by mass of isodecyl phthalate, 50 parts by mass of glass particles A, 0.2 After the mass part of the dispersant and 0.1 part by mass of the leveling agent, the mixture was kneaded in a roll mill and then subjected to filtration and defoaming under reduced pressure to obtain an insulating paste d.

The same operation as in Example 1 was carried out except that the insulating paste d was used, and an insulating film d was obtained.

(Example 6)

1 part by mass of 2,2-azobisisobutyronitrile, 10 parts by mass of trimethylolpropane propylene oxide modified triacrylate, 2 parts by mass of ethyl cellulose, and 30 parts by mass of acetic acid are stirred in advance Butyl ester, 6 parts by mass of butyl carbitol acetate, 1 part by mass of isodecyl phthalate, 50 parts by mass of glass particles A, 0.2 parts by mass of a dispersant, and 0.1 part by mass of a leveling agent Thereafter, the mixture was kneaded by a roll mill and then subjected to filtration and defoaming under reduced pressure to obtain an insulating paste e.

The insulating film e was obtained by the same operation as in Example 1 except that the coating film of the insulating paste e was used, and T ₁ was changed to 75 ° C and t ₁ was changed to 60 minutes.

(Example 7)

1 part by mass of 2,2-azobis(N-butyl-2-methylpropionamide), 10 parts by mass of trimethylolpropane propylene oxide-modified triacrylate, and 2 parts by mass of a mixture Ethylcellulose, 30 parts by mass of terpineol, 6 parts by mass of butyl carbitol acetate, 1 part by mass of isodecyl phthalate, 50 parts by mass of glass particles A, 0.2 parts by mass After dispersing agent and 0.1 part by mass of the leveling agent, the mixture was kneaded by a roll mill and then subjected to filtration and defoaming under reduced pressure to obtain an insulating paste f.

The insulating film f was obtained by the same operation as in Example 1 except that the insulating paste f was used, and T ₁ was changed to 120 ° C and t ₁ was changed to 60 minutes.

(Example 8)

1 part by mass of 2,2-azobis[2-(2-imidazolin-2-yl)propane]hydrogen dichloride, 10 parts by mass of trimethylolpropane propylene oxide-modified triacrylate, 2 Parts by mass of ethyl cellulose, 30 parts by mass of terpineol, 6 parts by mass of butyl carbitol acetate, 1 part by mass of isodecyl phthalate, 50 parts by mass of glass particles A, 0.2 After the mass part of the dispersant and 0.1 part by mass of the leveling agent, the mixture was kneaded in a roll mill, filtered, and defoamed under reduced pressure to obtain an insulating paste g. Since 2,2-azobis[2-(2-imidazolin-2-yl)propane]hydrogen chloride T _{10 is} low, although it tends to be slightly viscous, it is still practically problem-free.

The insulating film g was obtained by the same operation as in Example 1 except that the insulating paste g was used and the T ₁ was changed to 54 ° C and the t ₁ was changed to 60 minutes.

(Example 9)

1 part by mass of di-tertiary butyl peroxide, 10 parts by mass of trimethylolpropane propylene oxide-modified triacrylate, 2 parts by mass of ethyl cellulose, and 30 parts by mass of terpineol 6 parts by mass of butyl carbitol acetate, 1 part by mass of isodecyl phthalate, 50 parts by mass of glass particles A, 0.2 parts by mass of a dispersing agent, and 0.1 part by mass of a leveling agent, The mixture was kneaded by a roll mill and then subjected to filtration and defoaming under reduced pressure to obtain an insulating paste h.

The same operation as in Example 1 was carried out, except that the insulating paste h was used, and T ₁ was changed to 135 ° C and t ₁ was 60 minutes, respectively, as the insulating film h.

(Embodiment 10)

0.7 parts by mass of 1,1-azobis(cyclohexan-1-carbonitrile), 10 parts by mass of trimethylolpropane propylene oxide-modified triacrylate, 2 parts by mass of ethyl cellulose, 30 parts by stirring Parts by mass of terpineol, 6 parts by mass of butyl carbitol acetate, 1 part by mass of isodecyl phthalate, 50 parts by mass of glass After the glass particles A and 0.2 parts by mass of the dispersant and 0.1 parts by mass of the leveling agent, they were kneaded by a roll mill, filtered, and defoamed under reduced pressure to obtain an insulating paste i.

The same operation as in Example 1 was carried out except that the insulating paste i and t _{1 were used} for 60 minutes to obtain an insulating film i.

(Example 11)

1.2 parts by mass of 1,1-azobis(cyclohexan-1-carbonitrile), 10 parts by mass of trimethylolpropane propylene oxide-modified triacrylate, 2 parts by mass of ethyl cellulose, 30 parts by stirring Parts by mass of terpineol, 6 parts by mass of butyl carbitol acetate, 1 part by mass of isodecyl phthalate, 50 parts by mass of glass particles A, 0.2 parts by mass of dispersant, and 0.1 part by mass After the leveling agent is mixed, it is kneaded by a roll mill and then subjected to filtration and defoaming under reduced pressure to obtain an insulating paste j.

The same operation as in Example 1 was carried out except that the insulating paste j and t _{1 were used} for 60 minutes, and an insulating film j was obtained.

(Embodiment 12)

0.1 parts by mass of 1,1-azobis(cyclohexan-1-carbonitrile), 10 parts by mass of trimethylolpropane propylene oxide-modified triacrylate, 2 parts by mass of ethyl cellulose, 30 parts by stirring Parts by mass of terpineol, 6 parts by mass of butyl carbitol acetate, 1 part by mass of isodecyl phthalate, 50 parts by mass of glass particles A, 0.2 parts by mass of dispersant, and 0.1 part by mass After the leveling agent is mixed, it is kneaded by a roll mill and then subjected to filtration and defoaming under reduced pressure to obtain an insulating paste k.

The same operation as in Example 1 was carried out except that the insulating paste k and t _{1 were used} for 60 minutes to obtain an insulating film k.

(Example 13)

1.5 parts by mass of 1,1-azobis(cyclohexan-1-carbonitrile), 10 parts by mass of trimethylolpropane propylene oxide-modified triacrylate, 2 parts by mass of ethyl cellulose, and 30 parts by stirring Parts by mass of terpineol, 6 parts by mass of butyl carbitol acetate, 1 part by mass of isodecyl phthalate, 50 parts by mass of glass particles A, 0.2 parts by mass of dispersant, and 0.1 part by mass After the leveling agent was mixed, it was kneaded by a roll mill and then subjected to filtration and defoaming under reduced pressure to obtain an insulating paste 1.

The insulating film 1 was obtained by the same operation as in Example 1 except that the insulating paste 1 and t _{1 were used} for 60 minutes. Since the addition amount of 1,1-azobis(cyclohexan-1-carbonitrile) is large, it is considered that there is a tendency to precipitate slightly at the stage of the semi-cured film, but it is still in a practically problem-free range.

(Example 14)

0.8 parts by mass of 1,1-azobis(cyclohexan-1-carbonitrile), 7.9 parts by mass of trimethylolpropane propylene oxide-modified triacrylate, 2 parts by mass of ethyl cellulose, and 30 parts by stirring. Parts by mass of terpineol, 6 parts by mass of butyl carbitol acetate, 1 part by mass of isodecyl phthalate, 50 parts by mass of glass particles A, 0.2 parts by mass of dispersant, and 0.1 part by mass After the leveling agent is mixed, it is kneaded by a roll mill and then subjected to filtration and defoaming under reduced pressure to obtain an insulating paste m.

The same operation as in Example 1 was carried out except that the insulating paste m and t _{1 were used} for 60 minutes to obtain an insulating film m.

(Example 15)

Pre-stirring 1.1 parts by mass of 1,1-azobis(cyclohexan-1-carbonitrile), 10.8 parts by mass of trimethylolpropane propylene oxide-modified triacrylate, 2 mass Ethylcellulose, 30 parts by mass of terpineol, 6 parts by mass of butyl carbitol acetate, 1 part by mass of isodecyl phthalate, 50 parts by mass of glass particles A, 0.2 mass After dispersing agent and 0.1 part by mass of the leveling agent, the mixture was kneaded in a roll mill, filtered, and defoamed under reduced pressure to obtain an insulating paste n.

The same operation as in Example 1 was carried out except that the insulating paste n and t _{1 were used} for 60 minutes to obtain an insulating film n.

(Embodiment 16)

0.8 parts by mass of 1,1-azobis(cyclohexan-1-carbonitrile), 3.9 parts by mass of epoxy-modified glycerin propylene oxide triacrylate (EO 9 mol), and 3.9 parts by mass of trishydroxyl were previously stirred. Methylpropane propylene oxide modified triacrylate, 2.2 parts by mass of ethyl cellulose, 30 parts by mass of terpineol, 6 parts by mass of butyl carbitol acetate, 1 part by mass of phthalic acid Isodecyl ester, 50 parts by mass of glass particles A, 0.2 parts by mass of a dispersant, and 0.1 part by mass of a leveling agent were kneaded by a roll mill, followed by filtration and defoaming under reduced pressure to obtain an insulating paste o.

The same operation as in Example 1 was carried out, except that the insulating paste o and t _{1 were used} for 60 minutes, as the insulating film o.

(Example 17)

1.3 parts by mass of 1,1-azobis(cyclohexan-1-carbonitrile), 18.3 parts by mass of dipentaerythritol hexaacrylate, 1 part by mass of ethyl cellulose, and 30 parts by mass of a product are stirred in advance. Alcohol, 6 parts by mass of butyl carbitol acetate, 0.5 parts by mass of isodecyl phthalate, 50 parts by mass of glass particles A, 0.2 parts by mass of a dispersing agent, and 0.1 part by mass of a leveling agent The mixture was kneaded by a roll mill and then subjected to filtration and defoaming under reduced pressure to obtain an insulating paste p.

The same operation as in Example 1 was carried out except that the insulating paste p and t _{1 were used} for 60 minutes to obtain an insulating film p. Although a slight floating of the film is locally generated in the insulating film, it is still in a practically problem-free range.

(Embodiment 18)

1 part by mass of 1,1-azobis(cyclohexan-1-carbonitrile), 13.9 parts by mass of trimethylolpropane propylene oxide modified trienoate, 2 parts by mass of ethyl cellulose, and 2 parts by mass of ethyl cellulose, 30 parts by mass of terpineol, 6 parts by mass of butyl carbitol acetate, 1 part by mass of isodecyl phthalate, 50 parts by mass of glass particles A, 0.2 parts by mass of dispersant, and 0.1 mass After the portion of the leveling agent was mixed, it was kneaded by a roll mill and then subjected to filtration and defoaming under reduced pressure to obtain an insulating paste q.

The same operation as in Example 1 was carried out except that the insulating paste q and t _{1 were used} for 60 minutes to obtain an insulating film q.

(Embodiment 19)

0.58 parts by mass of 1,1-azobis(cyclohexan-1-carbonitrile), 5.8 parts by mass of trimethylolpropane propylene oxide modified trienoate, and 2 parts by mass of ethyl cellulose, 30 parts by mass of terpineol, 6 parts by mass of butyl carbitol acetate, 1 part by mass of isodecyl phthalate, 50 parts by mass of glass particles A, 0.2 parts by mass of dispersant, and 0.1 mass After the portion of the leveling agent was mixed, it was kneaded by a roll mill and then subjected to filtration and defoaming under reduced pressure to obtain an insulating paste r.

The same operation as in Example 1 was carried out, except that the insulating paste r and t _{1 were used} for 60 minutes, as the insulating film r.

(Embodiment 20)

0.17 parts by mass of 1,1-azobis(cyclohexan-1-carbonitrile), 17.3 parts by mass of trimethylolpropane propylene oxide modified trienoate, and 2 parts by mass were stirred in advance. Ethylcellulose, 30 parts by mass of terpineol, 6 parts by mass of butyl carbitol acetate, 1 part by mass of isodecyl phthalate, 50 parts by mass of glass particles A, 0.2 parts by mass After dispersing agent and 0.1 part by mass of the leveling agent, the mixture was kneaded by a roll mill and then subjected to filtration and defoaming under reduced pressure to obtain an insulating paste s.

The same operation as in Example 1 was carried out except that the insulating paste s and t _{1 were used} for 60 minutes, and an insulating film s was obtained. Although a slight floating of the film is locally generated in the insulating film, it is still practically problem-free.

(Example 21)

The same operation as in Example 1 was carried out except that T ₁ was changed to 88.5 ° C and t ₁ was 120 minutes, respectively, to obtain an insulating film a3.

(Example 22)

The same operation as in Example 1 was carried out except that T ₁ was changed to 98 ° C and t ₁ was 60 minutes, respectively, to obtain an insulating film a4.

(Example 23)

The same operation as in Example 1 was carried out except that T ₁ was changed to 118 ° C and t ₁ was changed to 5 minutes, respectively, to obtain an insulating film a5.

(Example 24)

The same operation as in Example 1 was carried out except that t ₁ was 240 minutes, and an insulating film a6 was obtained.

(Embodiment 25)

The same operation as in Example 1 was carried out except that t ₁ was 145 minutes, and an insulating film a7 was obtained.

(Example 26)

The same operation as in Example 1 was carried out except that T ₁ was changed to 78 ° C and t ₁ was changed to 750 minutes, respectively, to obtain an insulating film a8.

(Example 27)

The same operation as in Example 1 was carried out except that T ₁ was changed to 123 ° C and t ₁ was changed to 4 minutes, respectively, to obtain an insulating film a9.

(Comparative Example 1)

1 part by mass of 1,1-azobis(cyclohexan-1-carbonitrile), 2 parts by mass of ethyl cellulose, 40 parts by mass of terpineol, and 6 parts by mass of butyl carbitol acetic acid were stirred in advance. An ester, 1 part by mass of isodecyl phthalate, 50 parts by mass of glass particles A, 0.2 parts by mass of a dispersant, and 0.1 part by mass of a leveling agent, and then kneaded by a roll mill, followed by filtration and under reduced pressure. Defoaming, obtaining an insulating paste v.

The same operation as in Example 1 was carried out except that the insulating paste v and t _{1 were used} for 60 minutes to obtain an insulating film v.

(Comparative Example 2)

10 parts by mass of trimethylolpropane propylene oxide modified triacrylate, 2 parts by mass of ethyl cellulose, 30 parts by mass of terpineol, and 6 parts by mass of butyl carbitol acetate are stirred in advance. 1 part by mass of isodecyl phthalate, 50 parts by mass of glass particles A, 0.2 parts by mass of a dispersing agent, and 0.1 part by mass of a leveling agent, and then kneaded by a roll mill and then filtered and decompressed under reduced pressure. Bubble, get insulation paste w.

The same operation as in Example 1 was carried out except that the insulating paste w and t _{1 were used} for 60 minutes, and an insulating film w was obtained.

(Comparative Example 3)

The same operation as in Example 1 was carried out except that the semi-hardening step was not performed, and the insulating film a11 was obtained.

(Comparative Example 4)

The same operation as in Example 1 was carried out except that the change t ₁ was 5 minutes, and the insulating film a10 was obtained.

(Comparative Example 5)

The same operation as in Example 1 was carried out except that T ₁ was changed to 123 ° C and t ₁ was 60 minutes, respectively, to obtain an insulating film a12.

Table 1 summarizes the results of evaluation of the thermosetting component, the thermal polymerization initiator, the parameters for the semi-curing step, and the insulating film of Examples 1 to 28 and Comparative Examples 1 to 5.

Further, the smoothness of the insulating films obtained in Examples 1 to 27 and Comparative Examples 1 to 5 was evaluated in five stages of A to E. The evaluation criteria of A to E are 0 μm or more and less than 0.5 μm, A, 0.5 μm or more and less than 1 μm, B, 1 μm or more and less than 2 μm, C, 2 μm or more and less than 3 μm, D, and 3 μm or more, and E is not preferable. .

Further, the disadvantage of the insulating film is evaluated in five stages of A to E for cracks and bubbles. As a criterion for the evaluation of the cracks A to E, the cracks are 0 for A, the cracks are 1 for B, the cracks are 2 to 3 for C, and the cracks are 3 or more and less than 5 for D. Five or more are E, and E is not good. As a criterion for evaluating the bubbles A to E, 0 bubbles are A (very good), 1 to 3 bubbles are B, 3 to 5 bubbles are C, bubbles 5 to less than 10 are D, and bubbles are 10 The above is E, and E is not good.

(modulation of photosensitive conductive paste)

10 parts by mass of acrylic resin A (methacrylic acid/methyl methacrylate copolymer; acid value of 120; molecular weight of 10,000) and 5 parts by mass of trimethylolpropane propylene oxide modified triacrylate were previously stirred. 1 part by mass of 2-methyl-(4-methylphenylthio)-2- Olinone acetone, 1 part by mass of 2,4-diethylthioxanthone, 0.1 part by mass of dibutylhydroxytoluene, 15 parts by mass of ester alcohol (Texanol), 65 parts by mass of silver particles (particle diameter of 2 μm) 3 parts by mass of glass particles B, 0.2 parts by mass of a dispersant (SOLSPERSE 20000; manufactured by Lubrizol Co., Ltd., Japan), and 0.1 parts by mass of a leveling agent (L1980; manufactured by Nanben Chemical Co., Ltd.), followed by a roll mill After kneading, filtration and defoaming under reduced pressure were carried out to obtain a photosensitive conductive paste.

(Glass particle B: mass ratio of composition ratio, Bi ₂ O ₃ 73.0% by mass, ZnO 15.0% by mass, B ₂ O ₃ 8.0% by mass, BaO 2.0% by mass, SiO ₂ 1.5% by mass, Al ₂ O ₃ 0.5 mass %, average particle diameter D ₅₀ is 2.0 μm, and maximum particle diameter D _max is 10.0 μm)

(modulation of photosensitive glass paste)

32 parts by mass of the glass powder C, 8 parts by mass of the glass powder D, and 18 parts by mass of the acrylic resin B (addition of 20 parts by mass of glycidyl methacrylate (GMA) to styrene/methacrylic acid) a copolymer of methyl ester/methacrylic acid (copolymerization ratio: 30 parts by mass / 30 parts by mass / 40 parts by mass) as a photosensitive organic component, 12 parts by mass of polypropylene glycol dimethacrylate, and 4 parts by mass 2-benzyl-2-dimethylamino-1-(4- Phenylphenyl)-1-butanone, 25 parts by mass of γ-butyrolactone, 1 part by mass of 1,2,3-benzotriazole and 0.1 part by mass of hydroquinone monomethyl ether, followed by roll milling The base was kneaded and then subjected to filtration and defoaming under reduced pressure to obtain a photosensitive glass paste.

(Glass powder C: 7 mass% of lithium oxide, 22 mass% of cerium oxide, 33 mass% of boron oxide, 3% by mass of zinc oxide, 19 mass% of alumina, 6% by mass of magnesia, 5 mass% of cerium oxide, and calcium oxide 5 Mass %, average particle diameter D ₅₀ is 2.0 μm, and maximum particle diameter D _max is 10.0 μm)

(Glass powder D: sodium oxide/1% by mass, cerium oxide/40% by mass, boron oxide/10% by mass, alumina/33% by mass, zinc oxide/4% by mass, calcium oxide/9% by mass, titanium oxide/ 3 mass%, an average particle diameter D ₅₀ of 2.0 μm, and a maximum particle diameter D _max of 10.0 μm)

(modulation of phosphor paste)

The phosphor powder is stirred in advance (blue phosphor powder: BaMgAl ₁₀ O ₁₇ :Eu, red phosphor powder: (Y, Gd) BO ₃ : Eu, green phosphor powder: Zn ₂ SiO ₄ : Mn) After the ethyl cellulose resin, terpineol, and benzyl alcohol, the mixture was kneaded in a roll mill, filtered, and defoamed under reduced pressure to obtain a phosphor paste.

(Embodiment 28)

The above-mentioned photosensitive electrode paste was printed on a glass substrate (PD200; manufactured by Asahi Glass Co., Ltd.) to form a coating film, and dried at 120 ° C for 10 minutes. The coating film obtained by exposure through a hood was developed with a 0.5% sodium carbonate aqueous solution, and further sintered at 600 ° C under the atmosphere to form a strip-shaped address electrode having a thickness of 5 μm, a line width of 40 μm, and a pitch of 200 μm. pattern.

On the substrate on which the address electrode pattern was formed, the same operation as in Example 1 was carried out to form an insulating film. The formed insulating film did not generate bubbles or cracks, and the value of H1-H2 was 0.3 μm.

The photosensitive glass paste described above was printed on the obtained insulating film to form a coating film. The coating film obtained by exposure through a hood was developed with a 0.5% sodium carbonate aqueous solution, and further sintered at 600 ° C under the atmosphere to form a main separator including a thickness of 120 μm, a bottom width of 30 μm, and a pitch of 200 μm; A lattice-shaped separator of an auxiliary separator of 120 μm, a bottom width of 30 μm, and a pitch of 600 μm. No defects such as cracks or collapses were observed in the formed insulating film and the lattice-shaped separator.

The above-mentioned phosphor paste was applied between the main separators by a spraying method, and sintered at 450 ° C to form a phosphor layer having a thickness of 15 μm to complete the back sheet.

(Comparative Example 6)

The same operation as in Example 28 was carried out to form an address electrode pattern on a glass substrate. On the substrate on which the address electrode pattern was formed, the same operation as in Example 8 was carried out to form an insulating film. The insulating film formed did not generate bubbles or cracks, and the value of H1-H2 was 0.1 μm.

Further, in the same manner as in Example 28, a lattice-shaped separator and a phosphor layer were formed on the obtained insulating film to complete a back sheet for a plasma display.

Since the value of H1-H2 for the formed insulating film is less than 0.2 μm, a part of the main separator of the formed separator collapses and the phosphor layer oozes out.

(Comparative Example 7)

The same operation as in Example 28 was carried out to form an address electrode pattern on a glass substrate. On the substrate on which the address electrode pattern was formed, the same operation as in Example 9 was carried out to form an insulating film. The formed insulating film is not produced Bubbles or cracks, etc., the value of H1-H2 is 1.2 μm.

Further, in the same manner as in Example 28, a lattice-shaped separator and a phosphor layer were formed on the obtained insulating film to complete a back sheet for a plasma display.

Since the value of H1-H2 for the formed insulating film is more than 1.0 μm, the insulating film is cracked after the separator is sintered.

(modulation of photosensitive black electrode paste)

15 parts by mass of acrylic resin A, 10 parts by mass of trimethylolpropane propylene oxide modified triacrylate, and 1 part by mass of 2-methyl-(4-methylphenylthio)-2- Olinone acetone, 1 part by mass of 2,4-diethylthioxanthone, 0.1 part by mass of dibutylhydroxytoluene, 30 parts by mass of ester alcohol, 15 parts by mass of cobalt oxide (particle diameter: 400 nm), 30 parts by mass After the glass particles B, 0.2 parts by mass of a dispersant (SOLSPERSE 20000), and 0.1 parts by mass of a leveling agent (L1980), the mixture was filtered by a roll mill and defoamed under reduced pressure to obtain a photosensitive black electrode. paste.

(modulation of photosensitive white conductive paste)

10 parts by mass of acrylic resin A, 5 parts by mass of trimethylolpropane propylene oxide-modified triacrylate, and 1 part by mass of 2-methyl-(4-methylphenylthio)-2- Olinone acetone, 1 part by mass of 2,4-diethylthioxanthone, 0.1 part by mass of dibutylhydroxytoluene, 15 parts by mass of terpineol, 65 parts by mass of silver particles (particle size 2 μm), 3 mass Parts of the glass particles B, 0.2 parts by mass of a dispersant (SOLSPERSE 20000) and 0.1 parts by mass of a leveling agent (L1980), and then subjected to filtration by a roll mill and defoaming under reduced pressure to obtain a photosensitive white color. Conductive paste.

(Example 29)

On a glass substrate (PD200; manufactured by Asahi Glass Co., Ltd.), ITO was sputtered at a thickness of 500 Å, and a transparent electrode having a thickness of 500 Å was formed by photolithography. On the glass substrate on which the transparent electrode was formed, the above-mentioned photosensitive black electrode paste was printed by a screen printing method to form a coating film, and dried at 120 ° C for 10 minutes. Further, the above-mentioned photosensitive white electrode paste was printed by a screen printing method to form a two-layer coating film, which was dried at 120 ° C for 10 minutes. The two-layer coating film obtained by exposure through a light mask was developed with a 0.5% sodium carbonate aqueous solution, and then sintered at 600 ° C under the atmosphere to form a long-shaped confluence having a thickness of 5 μm, a line width of 40 μm, and a pitch of 200 μm. Row electrode pattern.

On the substrate on which the bus bar electrode pattern was formed, the same operation as in Example 1 was carried out to form an insulating film. The formed insulating film did not generate bubbles or cracks, and the value of H1-H2 was 0.3 μm. Finally, MgO is evaporated to form a protective film, and the front panel is completed.

The obtained front panel and the back panel obtained in Example 28 were sealed at 490 ° C using a glass frit sealing agent, and then heated to 410 ° C while vacuum evacuation was performed for 5 hours. Since the value of H1-H2 of the insulating film formed on the front panel is in a preferable range, the time when the degree of vacuum reaches 5.0 × 10 ^-5 Pa is 250 minutes. When the time when the degree of vacuum reaches 5.0 × 10 ^-5 Pa is 300 minutes or less, it is judged that there is no particular problem in the convenience of the manufacturing procedure.

The Xe-Ne mixed gas is sealed in the discharge space, and the device drives the circuit to perform aging to complete the plasma display panel. The obtained plasma display stably performs evoked discharge, and it is also good without interference.

(Embodiment 30)

On the substrate on which the bus bar electrode pattern was formed, the same operation as in Example 2 was carried out to form an insulating film. The insulating film formed did not generate bubbles or cracks, and the value of H1-H2 was 0.2 μm.

Using the obtained front panel and the back panel obtained in Example 28, the same operation as in Example 29 was carried out to complete the plasma display panel.

The time when the degree of vacuum reached 5.0 × 10 ^-5 Pa was 290 minutes without problems. The obtained plasma display is excellent in that the induced discharge is stably performed without interference.

(Example 31)

On the substrate on which the bus bar electrode pattern was formed, the same operation as in Example 3 was carried out to form an insulating film. The formed insulating film did not generate bubbles or cracks, and the value of H1-H2 was 0.4 μm.

Using the obtained front panel and the back panel obtained in Example 28, the same operation as in Example 29 was carried out to complete the plasma display panel.

The time when the degree of vacuum reached 5.0 × 10 ^-5 Pa was 240 minutes without problems. The obtained plasma display is excellent in that the induced discharge is stably performed without interference.

(Example 32)

On the substrate on which the bus bar electrode pattern was formed, the same operation as in Example 5 was carried out to form an insulating film. The insulating film formed did not generate bubbles or cracks, and the value of H1-H2 was 0.8 μm.

Using the obtained front panel and the back obtained in Example 28 The panel was subjected to the same operation as in Example 29 to complete the plasma display panel.

The time when the degree of vacuum reached 5.0 × 10 ^-5 Pa was 230 minutes without problems. The obtained plasma display was stably subjected to induced discharge. The interference occurs at the first place and then eliminated, and is in the range of no problem as a product.

(Comparative Example 8)

On the substrate on which the bus bar electrode pattern was formed, the same operation as in Example 8 was carried out to form an insulating film. The insulating film formed did not generate bubbles or cracks, and the value of H1-H2 was 0.1 μm.

Using the obtained front panel and the back panel obtained in Example 28, the same operation as in Example 29 was carried out to complete the plasma display panel.

The time when the degree of vacuum reached 5.0 × 10 ^-5 Pa was 370 minutes, which was a result of more than 300 minutes. The obtained plasma display is inferior in that the normal voltage is not subjected to induced discharge.

(Comparative Example 9)

On the substrate on which the bus bar electrode pattern was formed, the same operation as in Example 9 was carried out to form an insulating film. The insulating film formed did not generate bubbles or cracks, and the value of H1-H2 was 1.2 μm.

Using the obtained front panel and the back panel obtained in Example 28, the same operation as in Example 29 was carried out to complete the plasma display panel.

The time when the degree of vacuum reached 5.0 × 10 ^-5 Pa was 210 minutes without problems. The obtained plasma display is inferior in that the induced discharge is stably performed while the disturbance frequently occurs.

[Industrial availability]

The method of forming an insulating film of the present invention can be utilized in the manufacture of a plasma display element.

Claims (7)

A method for forming an insulating film, comprising: applying a coating film containing a thermal polymerization initiator, a thermosetting component, and glass particles to a substrate having irregularities to obtain a coating film; and heating the coating film to obtain a curing rate a semi-hardening step of 30 to 95% of the semi-hardened film; and a sintering step of heating the semi-cured film to obtain an insulating film, wherein the heating temperature of the semi-hardening step is set to T ₁ , and 10 of the thermal polymerization initiator When the hour half-life temperature is T ₁₀ , the relationship of T ₁₀ <T ₁ ≦T ₁₀ +30 ° C is satisfied. The method for forming an insulating film according to claim 1, wherein the semi-cured film is obtained by cooling the coated film after the heating in the semi-hardening step to a temperature T ₂ lower than the T ₁ . A method of forming an insulating film according to claim 2, wherein the T _{2 is} lower than the T ₁₀ . The method of forming an insulating film to any one of the requested item, such as 3, wherein the holding time T ₁ T is less than the half life of the heat of _{polymerization} initiator. The method for forming an insulating film according to claim 1, wherein the thermal polymerization initiator is a compound which becomes an active radical species by heating, and the 10-hour half-life temperature T ₁₀ is 60 to 110 °C. The method for forming an insulating film according to claim 1, wherein the thermosetting component contains a compound having three or more carbon-carbon unsaturated double bonds. The method for forming an insulating film according to claim 1, wherein the organic solid component of the insulating paste has a carbon-carbon unsaturated double bond density of 3 to 9 mmol/g.