TWI519581B - White hardening resin composition - Google Patents

Description

White curable resin composition

The present invention relates to a white curable resin composition having excellent shielding power, and more particularly to a white curable resin composition which can be used as a reflective film of a solder resist film or a reflective sheet of a circuit board such as a printed wiring board. And a printed wiring board and a reflection sheet having a cured product of the white curable resin composition.

The printed wiring board is formed on a substrate to form a pattern of a conductor circuit, and is used by soldering an electronic component in a soldering area of the drawing, and the circuit portion excluding the soldering region is covered with a solder resist film as a permanent protective film. Thereby, when the electronic component is soldered on the printed wiring board, the solder is prevented from adhering to an unnecessary portion, and the circuit conductor is prevented from being directly exposed to the air to be oxidized or corroded by humidity. Moreover, the shielding force of the solder resist film is used to prevent the pattern information of the conductor circuit from being seen from the outside.

In addition, in recent years, with the advancement of technology, the demand for miniaturization and weight reduction in the field of electrical appliances has increased. Accordingly, in order to arrange smaller electronic components at high density, the micro-pitch of the conductor circuit pattern of the printed wiring board has been sought. Chemicalization, miniaturization, and high precision. According to this, the solder resist film is required to have higher performance in terms of characteristics such as resolution, dimensional accuracy, and thin film formation. Therefore, in Patent Document 1, a solder resist composition which masks a conductor pattern pattern even if a solder resist film is thinned by blending a specific white pigment with a specific coloring pigment has been proposed, and Patent Document 2 has been proposed. Proposed by blending Cyanine is a white curable resin composition for printed wiring boards which has a high content and contains titanium oxide.

However, even if the specific coloring pigment proposed in Patent Document 1 is blended, the solder resist film becomes yellowish brown depending on the heat history when the solder resist composition is applied to the printed wiring board and hardened, and there is a pattern for the conductor circuit. The problem of reduced shielding power.

Further, in the white curable resin composition proposed in Patent Document 2, a pigment having a low discoloration property due to a heat history is used, so that phthalocyanine is blended. However, in the white curable resin composition of Patent Document 2, the resin component is yellowed by the heat history, and as a result, the solder resist film is discolored to a yellowish brown color, and there is a problem that the shielding force for the conductor circuit pattern is lowered.

In addition, in recent years, in order to reduce the environmental load, solar cells have attracted attention, and in order to improve the power generation efficiency of solar cells, a reflection sheet having high reflectance and excellent discoloration resistance is required.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Special Opening 2005-311233

[Patent Document 2] Special Opening 2009-238771

[Summary of the Invention]

In view of the above, an object of the present invention is to provide a white curable resin composition which is non-destructive in reflectance, resolution, dimensional accuracy, and the like. Each of the characteristics is excellent in the shielding power, and a cured product which suppresses discoloration due to the heat history can be obtained.

The aspect of the present invention is a white curable resin composition characterized by comprising: (A) a carboxyl group-containing photosensitive resin, (B) a photopolymerization initiator, (C) a diluent, (D) an epoxy compound, (E) Titanium oxide, (F) Threne-based blue colorant. The reduction-based blue colorant of the component (F) means a blue dye having a polycyclic fluorene skeleton and a reducing dye. Therefore, the reduced blue colorant of the present invention is a vat dye which is different from the above-described phthalocyanine which is a pigment.

The aspect of the present invention is a white curable resin composition containing 0.003 to 0.055 parts by mass of the above (F) reducing (Threne) blue coloring agent with respect to 100 parts by mass of the above (E) titanium oxide.

The aspect of the present invention is a white curable resin composition containing 40 to 300 parts by mass of the above (E) titanium oxide per 100 parts by mass of the carboxyl group-containing photosensitive resin.

The aspect of the invention is a printed wiring board characterized by having a cured product which hardens the white curable resin composition.

The aspect of the invention is a printed wiring board in which the cured product has a L* value of 70 or more, an a* value of -2.5 to -0.5, and a b* value of -6.0 to -2.5 in a film thickness of 20 μm.

The aspect of the invention is a reflection sheet characterized by having a film obtained by curing the white curable resin composition.

According to the present invention, a white curable resin composition which is a white pigment-containing titanium oxide and which has a non-destructive reflectance, an analytical property and a dimensional accuracy by blending a reducing blue coloring agent can suppress a heat history It is discolored and becomes a cured product excellent in shielding power. Further, when the cured product of the white curable resin composition of the present invention is applied onto the substrate on which the conductor pattern is formed, the difference between the color tone of the cured product on the conductor pattern pattern and the color tone of the cured product on the substrate can be reduced. . Therefore, a white curable resin composition which is a cured product excellent in the shielding force of the conductor circuit pattern can be obtained. In the above-mentioned aspect, it is considered that by blending the reducing blue coloring agent, even if the photosensitive resin containing a carboxyl group is yellowed by heat, the yellowing of the cured white curable resin composition can be suppressed, and the shielding force can be prevented. The reduction. In other words, it is considered that the photosensitive resin containing a carboxyl group is yellowed by the heat history, but it is affected by the heat history of the reduced blue coloring agent, and the yellowing of the cured white curable resin composition can be suppressed, and the cured product can be prevented. The shielding power is reduced.

By blending 0.003 to 0.055 parts by mass of a reducing (Threne) blue coloring agent with respect to 100 parts by mass of titanium oxide, the above hiding power is further enhanced. In addition, by blending 40 to 300 parts by mass of titanium oxide with respect to 100 parts by mass of the carboxyl group-containing photosensitive resin, it is possible to obtain a white curable resin having a high reflectance and a cured product excellent in resolution and dimensional accuracy. Things.

By coating the white curable resin composition of the present invention on a printed wiring board, the loss of reflectance, resolution, and dimensional accuracy can be suppressed, and discoloration due to heat history can be suppressed, and the shielding force for the conductor circuit pattern can be excellent. Solder mask film. For a hardened coating film having a film thickness of 20 μm, the L* value is 70 or more, the a* value is -2.5 to -0.5, and the b* value is -6.0 to -2.5, and the white color of the cured coating film is remarkable, and the efficiency can be formed. A printed wiring board such as a light-emitting diode element (LED) is used.

By coating the surface of the sheet-like base film with the white curable resin composition of the present invention, a reflection sheet having a reflective film which is non-destructive in reflectance, resolution, and dimensional accuracy can be obtained, and discoloration due to heat history can be suppressed. .

[Formation for implementing the invention]

Next, each component of the white curable resin composition of the present invention will be described. The white curable resin composition of the present invention is characterized by comprising (A) a carboxyl group-containing photosensitive resin, (B) a photopolymerization initiator, (C) a diluent, (D) an epoxy compound, and (E) oxidation. Titanium, (F) reduction blue colorant.

(A) carboxyl group-containing photosensitive resin

The carboxyl group-containing photosensitive resin is not particularly limited, and any of a photosensitive carboxyl group-containing resin having one or more photosensitive unsaturated double bonds and a carboxyl group-containing resin having no photosensitive unsaturated double bonds can be used. Examples of the component (A) include a radically polymerizable unsaturated monocarboxylic acid such as acrylic acid or methacrylic acid, which is at least a part of an epoxy group of a polyfunctional epoxy resin having two or more epoxy groups in the molecule. The reaction is carried out to obtain an epoxy group-modified (meth) acrylate, and the polybasic acid-modified epoxy (meth) acrylate obtained by reacting a polybasic acid or an anhydride thereof with the generated hydroxyl group.

The polyfunctional epoxy resin is preferably a bifunctional or higher epoxy resin. Either the epoxy equivalent is not particularly limited, but is generally 1000 or less, preferably 100 to 500. The polyfunctional epoxy resin may, for example, be a rubber modified epoxy resin such as a biphenyl type epoxy resin, a naphthalene type epoxy resin, a dicyclopentadiene type epoxy resin or a polyfluorene modified epoxy resin. , phenol-phenolic varnish type epoxy resin such as ε-caprolactone-modified epoxy resin, bisphenol A type, bisphenol F type, bisphenol AD type, etc., cresol novolac type ring such as o-cresol novolac type Oxygen resin, bisphenol A novolac type epoxy resin, cyclic aliphatic polyfunctional epoxy resin, glycidyl ester type polyfunctional epoxy resin, glycidylamine type multifunctional epoxy resin, heterocyclic type A functional epoxy resin, a bisphenol modified novolac type epoxy resin, a polyfunctional modified novolac type epoxy resin, a condensed epoxy resin having a phenol and an aromatic aldehyde having a phenolic hydroxyl group, and the like. Further, a halogen atom such as Br or Cl may be introduced into the resin. Among these, from the viewpoint of the flexibility of the coating film, a rubber-modified epoxy resin such as a polyfluorene-modified epoxy resin is preferable. These epoxy resins may be used singly or in combination of two or more.

The radically polymerizable unsaturated monocarboxylic acid to be used is not particularly limited, and examples thereof include acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, and the like, and at least one of acrylic acid and methacrylic acid (hereinafter sometimes referred to as (Meth)acrylic acid), particularly preferably acrylic acid. The methacrylic acid reactive agent is an epoxy (meth) acrylate. The reaction method of the epoxy resin and the radically polymerizable unsaturated monocarboxylic acid is not particularly limited, and for example, it can be reacted by heating an epoxy resin with acrylic acid in a suitable diluent.

a polybasic acid or a polybasic acid anhydride which reacts with a hydroxyl group formed by the reaction of the above epoxy resin with a radically polymerizable unsaturated monocarboxylic acid, and has a free resin The carboxyl group. The alkali acid or its acid anhydride to be used is not particularly limited, and either saturated or unsaturated can be used. Examples of the polybasic acid include succinic acid, maleic acid, adipic acid, citric acid, citric acid, tetrahydrofurfuric acid, 3-methyltetrahydrofurfuric acid, 4-methyltetrahydrofurfuric acid, and 3- Ethyltetrahydrofurfuric acid, 4-ethyltetrahydrofurfuric acid, hexahydrononanoic acid, 3-methylhexahydrophthalic acid, 4-methylhexahydrophthalic acid, 3-ethylhexahydrophthalic acid, 4- Ethyl hexahydrophthalic acid, methyltetrahydrofurfuric acid, methyl hexahydrofuric acid, cyclomethylenetetrahydrofurfuric acid, methylcyclomethylenetetrahydrofurfuric acid, trimellitic acid, homobenzene As the tetrabasic acid, diglycolic acid, etc., the polybasic acid anhydride can be exemplified by such an acid anhydride. These compounds may be used singly or in combination of two or more.

In the present invention, the polybasic acid-modified unsaturated monocarboxylic acid epoxy resin may be used as a photosensitive resin, but the carboxyl group of the polybasic acid-modified unsaturated monocarboxylic acid epoxy resin described above has 1 One or more of the radically polymerizable unsaturated groups are reacted with a glycidyl group-containing compound having an epoxy group, and a radically polymerizable unsaturated group is further introduced, and further, a photosensitive resin which improves photosensitivity can be further used.

The photosensitive resin which enhances the photosensitivity is a side chain of a polymer skeleton of a photosensitive resin of a precursor which is bonded to a precursor of a photosensitive resin by a reaction of a final glycidyl compound, so photopolymerization reactivity High, it can have excellent photographic properties. Examples of the compound having one or more radical polymerizable unsaturated groups and an epoxy group include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and pentaerythritol triacrylate. Glycidyl ether and the like. Further, the glycidyl group may have a complex number in one molecule. Has more than one of the above radical polymerizations The compound of the unsaturated group and the epoxy group may be used singly or in combination of two or more.

The lower limit of the acid value of the carboxyl group-containing photosensitive resin is 30 mg KOH/g, preferably 40 mgKOH/g, from the point of positive alkali development. In addition, the upper limit of the acid value is 200 mg KOH/g from the point of preventing dissolution of the exposed portion by the alkali developing solution, and is preferably 150 from the point of preventing deterioration of moisture resistance and electrical properties of the cured product. mgKOH/g.

Further, the lower limit of the weight average molecular weight of the carboxyl group-containing photosensitive resin is 3,000, preferably 5,000, from the viewpoint of the toughness of the cured product and the dryness of the touch. In addition, the upper limit of the weight average molecular weight is 200,000, preferably 50,000, from the viewpoint of compatibility with the diluent of the component (C) and smooth alkali developability.

As a carboxyl group-containing photosensitive resin, for example, ZFR-1124, FLX-2089 (above, manufactured by Nippon Kayaku Co., Ltd.), Cyclomer P (ACA) Z-250, and Cyclomer P (ACA) Z-300 are mentioned. (The above, manufactured by Daicel Chemical Industry Co., Ltd.), Ripoxy SP-4621 (made by Showa Polymer Co., Ltd.), and the like. These resins may be used singly or in combination of two or more.

(B) Photopolymerization initiator

The photopolymerization initiator is not particularly limited as long as it is generally used, and examples thereof include an anthraquinone initiator, a benzoin, a benzoin methyl ether, a benzoin ethyl ether, and a benzoin isopropyl group. Ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoethyl benzene, 2,2-dimethoxy-2-phenyl acetophenone, 2 ,2-diethoxy-2-phenylethyl benzene, 2-hydroxy- 2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-propane 1-ketone, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)one, benzophenone, p-phenylbenzophenone, 4,4'-diethyl Aminobenzophenone, dichlorobenzophenone, 2-methyl onionone, 2-ethyl onionone, 2-tert-butyl onionone, 2-amino onionone, 2-methylsulfide Choline ketone, 2-ethyl thiazolone, 2-chlorothianicone, 2,4-dimethylthiaxanone, 2,4-diethylthiane, benzyl dimethyl A ketal, an ethenyl dimethyl ketal, a p-dimethylamino benzoic acid ethyl ester, and the like. These may be used singly or in combination of two or more. The blending amount of the photopolymerization initiator is 5 to 25 parts by mass, preferably 8 to 20 parts by mass, per 100 parts by mass of the carboxyl group-containing photosensitive resin.

(C) thinner

The diluent is, for example, a photopolymerizable monomer of a reactive diluent, and the carboxyl group-containing photosensitive resin is sufficiently photocured to obtain a cured product having acid resistance, heat resistance, alkali resistance and the like. The photopolymerizable single system may, for example, be 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate. , polyethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, hydroxytrimethylacetic acid neopentyl glycol di(meth)acrylate, dicyclopentene Di(meth)acrylate, caprolactone modified dicyclopentenyl di(meth)acrylate, ethylene oxide modified di(meth)acrylate, allylated cyclohexyl di( Methyl) acrylate, trimeric isocyanate di(meth) acrylate, three Hydroxymethylpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide modification Trimethylolpropane tri(meth)acrylate, propylene (propylene oxyethyl) trimeric isocyanate, propionic acid modified dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, A lactone-modified reactive diluent such as dipentaerythritol hexa(meth) acrylate. These may be used singly or in combination of two or more. The blending amount of the above-mentioned reactive diluent is 2.0 to 40 parts by mass, preferably 10 to 35 parts by mass, per 100 parts by mass of the carboxyl group-containing photosensitive resin.

Further, in the case of the diluent, in order to adjust the viscosity or drying property of the white curable resin composition, the reactive diluent and the organic solvent of the non-reactive diluent may be used instead of the above reactive diluent. Examples of the organic solvent include ketones such as methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as toluene and xylene, alcohols such as methanol, isopropanol and cyclohexanol, and cyclohexane and methylcyclohexane. Solvents such as petroleum-based solvents such as alicyclic hydrocarbons, petroleum ethers, and petroleum brains, cellosolvants such as cellosolve and butyl cellosolve, carbitol such as carbitol and butyl carbitol , ethyl acetate, butyl acetate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, diethylene glycol monoethyl ether acetate Such as acetates and the like. These may be used singly or in combination of two or more. The blending amount in the case of using an organic solvent is preferably 10 to 500 parts by mass based on 100 parts by mass of the carboxyl group-containing photosensitive resin.

(D) epoxy compound

The epoxy compound is a hard coat film having sufficient mechanical strength to obtain a crosslinking density of the cured product. The epoxy compound is, for example, an epoxy resin. Examples of the epoxy resin include a bisphenol A type epoxy resin, a novolac type epoxy resin (a phenol novolak type epoxy resin, an o-cresol novolak type epoxy resin, a p-t-butylphenol novolac type, etc.). a bisphenol F-type or bisphenol S-type epoxy resin obtained by reacting epichlorohydrin with bisphenol F or bisphenol S, further having epoxyhexenyl, triepoxyalkylene, pentylene oxide Tricyclic ring-like epoxy resin, bis(2,3-epoxypropyl)trimeric isocyanate, triglycidyl ginseng (2-hydroxyethyl)trimeric isocyanate, etc. Glyceryl trimeric isocyanate, dicyclopentadiene type epoxy resin, adamantyl type epoxy resin. These compounds may be used singly or in combination of two or more. The blending amount of the epoxy compound is from 5 to 50 parts by mass, preferably from 10 to 30 parts by mass, per 100 parts by mass of the carboxyl group-containing photosensitive resin, from the point of obtaining a coating film having sufficient mechanical strength after curing.

(E) titanium oxide

The titanium oxide is used to whiten the cured product, and examples thereof include anatase-type titanium oxide and rutile-type titanium oxide. Any of anatase-type titanium oxide and rutile-type titanium oxide can be used, but anatase-type titanium oxide has higher whiteness than rutile-type titanium oxide, but has photocatalytic activity, and thus sometimes The discoloration of the resin in the white curable resin composition is caused. The rutile-type titanium oxide system hardly has photocatalytic activity, so that discoloration of the cured product can be prevented.

The average particle diameter of the rutile-type titanium oxide particles is not particularly limited, but is exemplified. Such as 0.01 ~ 1μm. The surface treatment agent for the rutile-type titanium oxide particles is also not particularly limited. For the rutile-type titanium oxide system, for example, Fujitsu Titanium Co., Ltd. ("TR-600", "TR-700", "TR-750", "TR-840", Ishihara Satoshi Co., Ltd." can be used. 550", "R-580", "R-630", "R-820", "CR-50", "CR-60", "CR-90", "CR-93", Titanium Industry (shares) "KR-270", "KR-310", "KR-380", Tayca ("JR-1000", "JR-805", "JR-806", etc. These systems can be used separately. Two or more kinds may be used in combination. The blending amount of titanium oxide is 30 to 800 parts by mass based on 100 parts by mass of the carboxyl group-containing photosensitive resin, and is preferably 35 to 500 mass in terms of balance between whiteness and resolution. In order to improve the balance between whiteness and resolution, it is especially suitable for 40 to 300 parts by mass.

(F) reduction blue colorant

The reduction-based blue coloring agent enhances the whiteness by increasing the L* value of the cured product formed from the white curable resin composition, and at the same time, prevents the yellowing of the cured product due to the heat history, thereby improving the shielding force. For blending. In particular, when the white curable resin composition of the present invention is used as a solder resist film of a printed wiring board, the difference between the color tone of the cured product on the conductor circuit pattern and the color tone of the cured material on the substrate of the printed wiring board can be reduced. That is, in particular, in order to prevent yellowing of a portion on the pattern of the conductor circuit, it is possible to suppress a decrease in the shielding force of the portion, so that a solder resist film having excellent shielding force can be formed. Further, the blending of the reduced blue colorant is improved compared to the blending of other blue colorants (for example, phthalocyanine, onion, and dioxazine). When the whiteness of the cured product is obtained, the resolution and dimensional accuracy of the cured coating film are further improved.

Specific examples of the reducing blue coloring agent include, for example, indanthrene blue-RS (C.I.69800) and indanthrene blue-BC (C.I.69825). In addition, the specific products are, for example, "LIONOGEN BLUE6510" manufactured by Toyo Ink Co., Ltd., "Threne Blue GA210" manufactured by Sanyo Pigment Co., Ltd., "Paliogen Blue" manufactured by BASF Corporation, "Monolite Blue-3R" manufactured by ICI Co., Ltd., Monolite-3RN" and so on. These may be used singly or in combination of two or more.

The blending amount of the blue coloring agent of the reducing system is such that the L* value of the cured product is a specific value or more, and the a* value and the b* value are set to a range in which the white color becomes apparent in white, and can be appropriately selected. The point at which the L* value of the cured product is whiteness is 70 or more, and preferably 80 or more. The a* value is a point at which the reddish color of the hardened material is suppressed and the green color is made white, which is preferably in the range of -2.5 to -0.5, and the copper band red which prevents the hardened material from being coated is recognized. Especially suitable for the range of -2.0~-1.0. The b* value is a point which suppresses the yellowing of the hardened material and the purple color and makes the white obvious. It should be in the range of -6.0 to -2.5, and the copper ribbon yellow which prevents the conductor pattern covered by the hardened material is recognized. It is especially suitable for the range of -5.0 to -3.0.

In the present invention, when the white color is adjusted in the range of the L* value, the a* value, and the b* value described above, for example, the lower limit of the blending amount of the blue-based coloring agent is based on the mass of the titanium oxide 100. For the case of suppressing the color of the white color of the cured product by reddish and yellowish, and making the L* value 70 or more, 0.003 parts by mass, the conductor pattern for preventing the hardened object from being coated The point where the copper color is recognized to improve the shielding property is preferably 0.004 parts by mass, and the point of visually vivid whiteness is obtained, and is particularly preferably 0.01 parts by mass. The upper limit of the amount of the blue coloring agent to be reduced is 100% by mass of titanium oxide, and the green color and the purple color are adjusted to adjust the white color of the cured product, and the L* value is 70 or more. The point is 0.055 parts by mass, and the point where the copper color of the conductor pattern coated with the cured product is prevented from being observed to improve the shielding property is preferably 0.053 parts by mass, and the point of visually vivid whiteness is obtained, particularly preferably 0.050 parts by mass.

That is, the white curable resin composition of the present invention takes into consideration the L* value, the a* value, and the b* value of the cured product, and blends the above-mentioned (A) to (F) components at a specific blending ratio. Or any of the following ingredients.

In the white curable resin composition of the present invention, in addition to the above components (A) to (F), various additives such as an antifoaming agent, various additives, extender pigments, tackifiers, etc. may be appropriately blended as needed. .

A known one can be used for the antifoaming agent, and examples thereof include polyoxymethylene, hydrocarbon, and acrylic. Examples of the additive include a dispersant of a coupling agent such as a decane system, a titanate system, or an alumina system, a boron trifluoride-amine complex, dicyandiamide (DICY) and derivatives thereof, and an organic acid. A potential hardener such as hydrazine, diamine malononitrile (DAMN) and its derivatives, melamine and its derivatives, hydrazine and its derivatives, amine quinone imine (AI) and polyamines, Metal salts of ethyl acetonylacetate such as acetate Zn and acetoxyacetate Cr, enamine, tin octylate, sulfonium salt of the fourth order, triphenylphosphine, imidazole, imidazolium and triethanolamine borate And other hardening accelerators. The body pigment is used to increase the physical strength of the hardened material, and examples thereof include cerium oxide, barium sulfate, and oxygen. Aluminum, aluminum hydroxide, talc, mica, etc. Further, examples of the tackifier include organic bentonite.

The method for producing the white curable resin composition of the present invention described above is not limited to a specific method, but for example, after blending the above components at a specific ratio, three rolls, a ball mill, and a sanding can be used at room temperature. A kneading method such as a machine or a stirring means such as a super mixer or a planetary mixer is kneaded or mixed to produce. Further, before the above-mentioned kneading or mixing, kneading or preliminary mixing may be prepared as needed.

Hereinafter, a method of applying the white curable resin composition of the present invention described above will be described. First, an example in which the white curable resin composition of the present invention is applied as a solder resist film to a printed wiring board will be described.

The white curable resin composition of the present invention produced as described above is used, for example, on a printed wiring board having a circuit pattern formed by etching a copper foil, using a screen printing method, a roll coating method, a rod coating method, or a spray coating method. The method is applied to a desired thickness by a method such as a curtain coating method or a gravure coating method, and the solvent is volatilized in a white curable resin composition, and is heated at a temperature of about 60 to 80 ° C for about 15 to 60 minutes. Dry to form a non-stick coating. Thereafter, a negative film having a pattern in which light transmittance is formed outside the circuit pattern region is adhered to the applied white curable resin composition, and ultraviolet rays are irradiated thereon. Then, the ruthenium coating film was developed by removing the non-exposed regions corresponding to the aforementioned regions with a dilute aqueous alkali solution. In the developing method, a spraying method, a spraying method, or the like can be used, and the dilute alkali aqueous solution used is generally a 0.5 to 5% sodium carbonate aqueous solution, but other bases can also be used. Then, it is aged for 20 to 80 minutes in a hot air circulating type dryer of 130 to 170 ° C, and then coated. The film is thermally cured to form a cured coating film of a desired white curable resin composition on a printed wiring board.

An electronic circuit unit can be formed by soldering electronic parts by a jet welding method, a reflow soldering method, or the like on a printed wiring board coated with the cured coating film obtained in this manner.

Next, an example of a method for producing a reflection sheet by applying the above-described white curable resin composition to the surface of a sheet-shaped base film will be described. After the surface of the sheet-like base film is washed with, for example, an acid treatment, the white curable resin composition produced as described above is applied to the desired thickness on the surface to be cleaned by a specific coating means (for example, 5~100μm thickness). After the application, the film is heated at a temperature of about 60 to 80 ° C for about 15 to 60 minutes to form a non-stick coating film. Then, it is aged at a temperature of about 130 to 170 ° C for 10 to 80 minutes, and a white white reflective film is formed by forming a white hard coating film on the surface of the sheet-like base film.

The material of the sheet-like base film is not particularly limited, and examples thereof include polyimide, polyethylene terephthalate (PET), polyvinyl fluoride (PVF), and ethylene fluoride. Propylene copolymer (FEP), polytetrafluoroethylene (PTFE), linaloamine, polyamine. Yttrium, epoxy, polyetherimide, polyfluorene, polyethylene naphthalate (PEN), liquid crystal polymer (LCP), and the like.

Although the coating method is generally used for printing by a screen printing method using a printing mask, it is not particularly limited as long as it is a coating method which can be uniformly applied. Coating methods other than the screen printing method include, for example, a spray coater, a hot melt coater, a bar coater, a thin coater, a knife coater, a knife coater, an air knife coater, and a curtain coater. , roll coater, gravure coater, flat Printing, dip coating, brushing, etc.

Hereinafter, an example of the method of using the above-mentioned reflection sheet will be described. The reflection sheet can be used, for example, as a backlight sheet on the back side of the solar cell module, that is, on the surface opposite to the surface exposed to the insolation. When a reflection sheet is used as the backlight sheet, the power generation element of the solar cell module is transmitted through the solar cell module without being exposed to light, and is reflected by the reflection film of the reflection sheet to return to the solar cell module from the back side of the solar cell module. Inside the group, the power generation efficiency of the solar cell module is improved. Further, the method of disposing the reflection sheet on the back surface of the solar cell module is a method of directly bonding to the back surface of the solar cell module using, for example, an adhesive or an adhesive tape.

When the reflection sheet is used for a backlight sheet of a solar cell module, for example, a polyethylene terephthalate film having a thickness of 40 μm is used for the base film. Moreover, the white curable resin composition is applied so that the film thickness after hardening becomes a specific value (for example, 20-23 micrometers). Further, the application site of the white curable resin composition is preferably applied to the surface of the base film opposite to the back surface of the solar cell module.

The white curable resin composition of the present invention may be used in a backlight for a street lamp or a surface of a backlight of an LED, etc., in addition to the above-described use, by an appropriate coating method.

[Examples]

Next, the embodiments of the present invention will be described, but the present invention is not limited by the examples as long as it does not exceed the gist thereof.

Examples 1 to 7 and Comparative Examples 1 to 4

Each component shown in the following Table 1 was blended at the blending ratio shown in the following Table 1, and prepared by mixing with a stirrer, and then mixed and dispersed at room temperature using three rolls, and prepared in Examples 1 to 7 and Comparative Examples. A white curable resin composition used in 1 to 4. Then, the prepared white curable resin composition was applied onto a substrate by using a test piece production step described later to prepare a test piece. Moreover, the blending amount of each component shown in the following Table 1 is a mass part unless otherwise specified.

The details of each component in Table 1 are as follows.

(A) carboxyl group-containing photosensitive resin

. Cyclomer P (ACA). Z-300: a carboxyl group-containing resin manufactured by Daicel Chemical Industry Co., Ltd. using a resin copolymerized with acrylic acid.

(B) Photopolymerization initiator

. Irgacure 819: bis(2,4,6-trimethylbenzylidene)-phenylphosphine oxide, manufactured by Ciba Specialty Chemicals.

. DAROCURE TPO: 2,4,6-trimethylbenzimidyl diphenylphosphine oxide manufactured by Ciba Specialty Chemicals.

(C) thinner

. Aronix M245: East Asian synthetic (stock), polyethylene glycol diacrylate.

. EDGAC: Sanyo Chemical Co., Ltd., diethylene glycol monoethyl ether acetate.

(D) epoxy compound

. YX-4000: Japan Epoxy Resin (share), dimethyl phenol type epoxy resin.

(E) titanium oxide

. CR-93: Ishihara Industry Co., Ltd., rutile type titanium oxide.

(F) reducing (Threne) blue colorant

. LIONOGEN BLUE 6510: Toyo Ink Manufacturing Co., Ltd.

(G) Other, KS-66 is a polyfluorene-based defoamer manufactured by Shin-Etsu Chemical Co., Ltd. The additive R-974 is a shake-modifying agent made by Japan Aerosil Co., Ltd., a potential hardener made by DICY-7 Japan Epoxy Resin, and melamine is also a latent hardener. LIONOL BLUE 7350: A phthalocyanine blue colorant made by Toyo Ink Manufacturing Co., Ltd. Test film making steps:

A glass epoxy substrate (manufactured by Panasonic Electric Co., Ltd., double-sided copper foil laminate R-1766, thickness 1.6 mmt, conductor thickness 50 μm) formed with a conductor pattern was subjected to surface treatment by polishing, and then screen-printed. In the method, the white curable resin compositions of Examples 1 to 7 and Comparative Examples 1 to 4 were applied, and then pre-dried at 80 ° C for 20 minutes (in the BOX furnace for 25 minutes) in a BOX furnace. After preliminary drying, the film was exposed to 500 m J/cm ² for 1 minute using an exposure apparatus (HMW-680GW manufactured by OAK Co., Ltd.), and then developed at 30 ° C and a 1% sodium carbonate aqueous solution. After the development, a cured film of a white curable resin composition was formed on a glass epoxy substrate by aging at 150 ° C for 60 minutes (70 minutes in a BOX furnace) to prepare a test piece. The thickness of the hardened coating film is 20 to 23 μm.

Evaluation (1) The shielding force for the conductor pattern

After the electroless gold plating treatment, after the reflow treatment, a pressure cooker (Pressure Cooker) treatment was performed, and the shielding force of the white coating film on the conductor pattern of the copper foil was visually observed. The evaluation is based on the following benchmarks.

◎: There is no difference between the pattern on the conductor pattern and the color tone on the substrate.

○: The edge of the conductor pattern is slightly yellowed.

△: There is a slight yellowing on the conductor pattern.

×: There is no change in the pattern of the conductor.

In the electroless gold plating treatment, the test piece was immersed in a plating bath at 85 ° C placed in an electroless nickel plating solution (trade name "Melplate NI-865T", manufactured by Meltex Co., Ltd.) for 15 minutes, and then immersed in an electroless gold plating solution. (The product name "Melplate AU-601", manufactured by Meltex Co., Ltd.) was placed in a 90 ° C plating bath for 10 minutes. The reflow treatment was performed at a preheating temperature of 60 to 120 ° C, a temperature increase rate of 1 ° C / sec, and a peak temperature of 230 ° C. 30 seconds. The pressure cooker treatment was carried out at 121 ° C, 100% RH, and 72 hours.

(2) Hue

After the electroless gold plating treatment, after the reflow treatment, the test piece which has been subjected to the pressure cooker treatment is measured by a color difference meter SE2000 (Nippon Denshoku Industries Co., Ltd.) on the conductor pattern of the glass epoxy substrate and the glass epoxy substrate. Luminance (L* value) and Chromatic index (a* value, b* value) on the substrate.

(3) Reflectance (%)

Initial stage: For the post-maturing test piece, it is made by spectrophotometer U-3410 ((Hybrid) Hitachi, Ltd.: 60 mm integrating sphere), the reflectance at 450 nm was measured.

After irradiation: To assess the light fastness who test piece after post-curing, for 50J / cm UV irradiation of ² (300 ~ 450nm of the UV, 2 minutes), spectrophotometer U-3410 ((shares) manufactured by Hitachi system: 60 mm integrating sphere), the reflectance of the test piece of 450 nm was measured.

After heating: For the evaluation of heat resistance, the test piece after post-aging was heated at 170 ° C for 50 hours, and then made by spectrophotometer U-3410 (manufactured by Hitachi, Ltd.: 60 mm integrating sphere), the reflectance of the test piece of 450 nm was measured.

(4) Analytical

The gap between the residual line of the exposed portion formed by the specific mask (line width 30 to 130 μm) and the removal was visually confirmed.

(5) undercut

The glass epoxy substrate on which the line of the cured coating film was formed was cut by using a mask having a width of 100 μm, and the line was observed from the cut surface, and the width (x) and the width of the bottom side (deep side) on the surface side of the line (y) were measured. , the undercut value is evaluated from (xy)/2.

In Examples 1 to 7 and Comparative Examples 1 to 4, the results of the shielding force, color tone, reflectance, resolution, and undercut of the conductor pattern are shown in Table 2.

From Table 2, the examples in which the reduced blue colorant was blended were compared with Comparative Example 1 in which the blue colorant was not blended and Comparative Examples 2 to 4 in which the phthalocyanine blue colorant was blended, and the glass was inhibited. The yellowing of the hardened coating film on the conductor pattern of the epoxy substrate. Further, the color index (a* value, b* value) on the conductor pattern of the glass epoxy substrate of Examples 1 to 7 and the color index (a* value, b* value) on the substrate of the glass epoxy substrate. The difference is smaller than that of Comparative Examples 1 to 4 (in the embodiment, the difference of the a* value is 0.2 at the maximum, and the difference of the b* value is 0.3 at the maximum, but in the comparative example, the difference of the a* value is 0.4 at the minimum. The aforementioned difference in the b* value is a minimum of 0.4), so that in the embodiment, the difference in hue between the conductor pattern and the substrate is lowered. Therefore, each embodiment is excellent in the shielding force for the conductor pattern.

In particular, from Examples 1 to 5 and Examples 6 and 7, the reducing blue coloring agent was blended in a range of 0.0036 to 0.0375 parts by mass based on 100 parts by mass of the titanium oxide, and the shielding force against the conductor pattern was further improved. Further, in Examples 1 to 5, the a* value was -2.5 to -0.5, and the b* value was -6.0 to -2.5, and the white color of the cured coating film was further more conspicuous.

The examples in which the reduced blue colorant was blended were able to obtain reflectances of the same degree or more as Comparative Examples 1 to 4 of the unblended blue colorant and Comparative Examples 2 to 4 of the blended phthalocyanine blue colorant. , analytical and undercut values. In particular, from Examples 1 to 3 and Comparative Examples 2 to 4, the cured coating film in which the reducing blue coloring agent was blended was more excellent in resolution than the cured coating film in which the phthalocyanine-based blue coloring agent was blended. Also, the undercut value is smaller and the dimensional accuracy is better.

[Industry use possibility]

The white curable resin composition of the present invention can obtain a non-destructive anti- Reflectivity, resolution, and dimensional accuracy, and excellent shielding power, and suppression of discoloration due to thermal history, such as reflection on the solder mask of printed wiring boards, backlights of solar cell modules, etc. The use of films and other fields is of high value.

Claims (6)

A white curable resin composition characterized by comprising: (A) a carboxyl group-containing photosensitive resin, (B) a photopolymerization initiator, (C) a diluent, (D) an epoxy compound, (E) titanium oxide, (F) Threne is a blue colorant. The white curable resin composition according to the first aspect of the invention, wherein the (F) reducing (Threne) blue coloring agent is contained in an amount of 0.003 to 0.055 parts by mass based on 100 parts by mass of the titanium oxide (E). The white curable resin composition of the first aspect of the invention, wherein the (E) titanium oxide is contained in an amount of 40 to 300 parts by mass based on 100 parts by mass of the carboxyl group-containing photosensitive resin. A printed wiring board characterized by having a cured product obtained by curing the white curable resin composition according to any one of claims 1 to 3. The printed wiring board of claim 4, wherein the cured product has a L* value of 70 or more, an a* value of -2.5 to -0.5, and a b* value of -6.0 to -2.5 in a film thickness of 20 μm. A reflection sheet comprising a film obtained by curing a white curable resin composition according to any one of claims 1 to 3 of the patent application.