Electroplating-resistant composition and dry film prepared therefrom, cured product, and electrode for solar cell

Abstract

Provided are an electroplating-resistant composition and a dry film prepared therefrom, a cured product, and an electrode for a solar cell, which composition has good electroplating resistance, and can reduce the content of carbon residue left by exposure and development and improve adhesiveness. The electroplating-resistant composition comprises: (A) an epoxy-modified acrylic resin, (B) a co-polymerized acrylic resin, (C) a polyfunctional acrylic monomer, and (D) a photopolymerization initiator, wherein relative to the total mass of the epoxy-modified acrylic resin (A) and the co-polymerized acrylic resin (B) in terms of solid components, the content of the co-polymerized acrylic resin (B) is 10-50 mass%, and the photopolymerization initiator (D) comprises an acylphosphine-oxide-based photopolymerization initiator.

Description

Electroplating resist composition, dry film thereof, cured product and electrode for solar cell Technical Field

[0001] The present invention relates to an anti-electroplating composition, in particular to an anti-electroplating composition used in manufacturing an electrode of a solar cell, and its dry film, cured product and an electrode of a solar cell using the same, belonging to the field of anti-electroplating materials used in solar cell manufacturing. Background Art

[0002] Globally, energy and environmental issues are receiving increasing attention, and the use of new energy sources such as solar energy is being actively promoted. Solar cells are devices that directly convert light energy into electrical energy through the photoelectric or photochemical effects. Currently, crystalline silicon solar cells that operate using the photovoltaic effect are the mainstream and have been applied in many fields, including transportation, communications, meteorology, satellites, lighting, and power stations.

[0003] Various research and development efforts have been actively carried out on solar cell electrodes, which are core components of solar cells, and their manufacturing methods. In order to further reduce the cost and increase the efficiency of solar cells, the use of electroplating to produce metal electrodes for solar cells has also attracted much attention. This method mainly replaces expensive silver partially or completely with lower-cost metals such as copper and nickel. When using electroplating to produce electrodes, it is necessary to define the position and size of the metal electrodes on the surface of the solar cell through a graphic mask, and use anti-plating ink for the mask opening process.

[0004] Patent Document 1 discloses a polyacrylate resin containing silicone side chains, formed by free radical polymerization of various acrylate monomers with a silicone resin containing carbon-carbon double bonds. The resulting alkali-soluble, electroplating-resistant photosensitive resin exhibits excellent etching resistance and electroplating resistance, and can be used to prepare electroplating-resistant inks. The resin aims to improve adhesion through the hydrolysis of silicone, and does not address the carbon content remaining after development.

[0005] Patent Document 2 discloses a method for printing an inexpensive, grid-lined, plating-resistant ink, replacing the expensive dry film. After printing, the ink only needs to be cured by UV or thermal baking before plating, making it suitable for large-scale production. However, no research was conducted on how to reduce the carbon content left after development or improve acid resistance and adhesion.

[0006] Patent Document 3 discloses a matte solder mask ink prepared using an acrylic copolymer resin, achieving excellent matte and curing properties. The preparation method is simple, the raw material costs are low, the production requirements are minimal, and large-scale production is possible. However, no research has been conducted on how to reduce the carbon content left after development or improve acid resistance and adhesion.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: CN108003271A

[0010] Patent Document 2: CN109427917A

[0011] Patent Document 3: CN110804339A

[0012] Summary of the Invention

[0013] Problems to be solved by the invention

[0014] Previous plating-resistant inks used to manufacture solar cell electrodes suffered from carbon residue and acid resistance issues, resulting in insufficient adhesion to the plated metal grid lines, leading to grid dropout (copper grid line detachment). This can lead to reduced overall module power and localized overheating, shortening module lifespan and, in severe cases, potentially damaging the cell assembly. Therefore, there is an urgent need to develop a plating-resistant ink that maintains plating resistance while maintaining low carbon residue (less than 5%) and preventing grid dropout.

[0015] Solutions for solving problems

[0016] The present inventors conducted in-depth research and found that by using a specific main resin and adjusting the ratio between the main resin and the monomer, the carbon residue on the battery cell after ink development and washing can be reduced, the acid resistance can be improved, and ultimately the adhesion of the copper grid after copper plating with the anti-electroplating composition can be improved, thereby completing the present invention.

[0017] That is, the present invention is as follows.

[0018] 1. A plating resist composition comprising (A) an epoxy-modified acrylic resin, (B) a copolymerized acrylic resin, (C) a multifunctional acrylic monomer, and (D) a photopolymerization initiator, wherein the copolymerized acrylic resin (B) accounts for 10 to 50% by mass relative to the total mass of the (A) epoxy-modified acrylic resin and the copolymerized acrylic resin (B) in terms of solid content, and the photopolymerization initiator (D) comprises an acylphosphine oxide-based photopolymerization initiator.

[0019] 2. The plating resist composition according to item 1, wherein the epoxy-modified acrylic resin (A) is at least one of the following resins:

[0020] reacting a multifunctional epoxy resin with an unsaturated monocarboxylic acid, and reacting a saturated or unsaturated polyacid anhydride with the generated hydroxyl group to obtain a carboxyl group-containing resin; and

[0021] A carboxyl group-containing resin is obtained by reacting a polyfunctional epoxy resin with an unsaturated monocarboxylic acid and reacting a saturated or unsaturated polybasic acid anhydride with the generated hydroxyl group, to which a compound having one epoxy group and one or more (meth)acryloyl groups is further added.

[0022] 3. The anti-electroplating composition according to 1 or 2, characterized in that the (B) copolymerized acrylic resin is a copolymerized resin having a carboxyl group obtained by reacting (a) a carboxyl group-containing (meth) acrylic copolymerized resin with (b) a compound having an ethylene oxide ring and an ethylenically unsaturated group in one molecule.

[0023] 4. The plating resist composition according to 3, wherein the amount of the polyfunctional acrylic monomer (C) is 12 to 35 parts by mass based on 100 parts by mass of the total mass of the (A) epoxy-modified acrylic resin and the (B) copolymerized acrylic resin in terms of solid content.

[0024] 5. The plating resist composition according to 1 or 2, characterized in that the (D) photopolymerization initiator further comprises a benzophenone-based photopolymerization initiator, an α-aminoacetophenone-based photopolymerization initiator, and a thioxanthone-based photopolymerization initiator.

[0025] 6. Use of the plating resist composition according to any one of 1 to 5 above for producing an electrode for a solar cell.

[0026] 7. A dry film, characterized in that it is obtained by coating the plating resist composition according to any one of 1 to 5 on a carrier film and drying the coating.

[0027] 8. A cured product, characterized in that it is obtained by curing the plating resist composition according to any one of 1 to 5.

[0028] 9. A cured product, characterized in that it is obtained by curing the resin layer of the dry film according to 8.

[0029] 10. An electrode for a solar cell, characterized by comprising the cured product according to 8 or 9.

[0030] Effects of the Invention

[0031] According to the present invention, a plating resist composition having low carbon residue on solar cell cells, high resolution, good acid resistance and high copper grid adhesion can be provided, as well as a dry film, a cured product and a solar cell electrode using the same. DETAILED DESCRIPTION

[0032] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The word "exemplary" is used herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior or preferred over other embodiments.

[0033] In addition, numerous specific details are provided in the following detailed description to better illustrate the present invention. Those skilled in the art will appreciate that the present invention can be practiced without certain specific details. In other instances, methods, means, equipment, and steps well known to those skilled in the art are not described in detail in order to highlight the main points of the present invention.

[0034] Unless otherwise stated, the units used in this specification are international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0035] In this specification, the use of "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

[0036] References throughout this specification to "some specific / preferred embodiments," "other specific / preferred embodiments," "embodiments," etc., mean that the particular elements (e.g., features, structures, properties, and / or characteristics) described in connection with the embodiments are included in at least one embodiment described herein and may or may not be present in other embodiments. Furthermore, it should be understood that the elements may be combined in any suitable manner in various embodiments.

[0037] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints A and B.

[0038] In this specification, (meth)acrylic acid is a term that collectively refers to acrylic acid, methacrylic acid, and a mixture thereof, and the same applies to other similar expressions.

[0039] The present invention provides a plating resist composition, characterized in that it contains (A) an epoxy-modified acrylic resin, (B) a copolymerized acrylic resin, (C) a multifunctional acrylic monomer, and (D) a photopolymerization initiator, wherein the copolymerized acrylic resin (B) accounts for 10 to 50% by mass relative to the total mass of the (A) epoxy-modified acrylic resin and the copolymerized acrylic resin (B) in terms of solid content, and the photopolymerization initiator (D) contains an acylphosphine oxide-based photopolymerization initiator.

[0040] Hereinafter, each component of the plating resist composition of the present invention will be described in detail.

[0041] (A) Epoxy-modified acrylic resin

[0042] The epoxy-modified acrylic resin (A) contained in the plating resist composition of the present invention is a resin having multiple (meth)acryloyl groups in its molecule and is cured by polymerization and / or crosslinking via the ethylenically unsaturated double bonds of the (meth)acryloyl groups upon irradiation with light.

[0043] (A) The epoxy-modified acrylic resin is not particularly limited, and may be, for example, a resin having a plurality of (meth)acryloyl groups in a molecule obtained by modifying an epoxy resin with acrylic acid.

[0044] In addition, from the perspective of imparting alkali developability, it is preferred that the epoxy-modified acrylic resin (A) has multiple carboxyl groups in addition to multiple (meth)acryloyl groups in the molecule. From the perspective of alkali developability and resolution, the acid value of the epoxy-modified acrylic resin is preferably 5 to 100 mgKOH / g, more preferably 10 to 90 mgKOH / g, and even more preferably 20 to 80 mgKOH / g.

[0045] Epoxy-modified acrylic resins typically include those obtained by reacting a multifunctional epoxy resin with (meth)acrylic acid and adding a dibasic acid anhydride to the hydroxyl groups present in the side chains; and those obtained by further adding a compound having one epoxy group and one or more (meth)acryloyl groups in the molecule to the resin. Examples of compounds having one epoxy group and one or more (meth)acryloyl groups include glycidyl (meth)acrylate, α-methylglycidyl (meth)acrylate, and 3,4-epoxycyclohexylmethyl methacrylate.

[0046] Examples of polyfunctional epoxy resins useful for synthesizing epoxy-modified acrylic resins include bisphenol A epoxy resins, bisphenol F epoxy resins, hydrogenated bisphenol A epoxy resins, brominated bisphenol A epoxy resins, bisphenol S epoxy resins, phenol novolac epoxy resins, cresol novolac epoxy resins, bisphenol novolac epoxy resins, biphenyl epoxy resins, naphthol epoxy resins, naphthalene epoxy resins, dicyclopentadiene epoxy resins, dicyclopentadiene novolac epoxy resins, triphenylmethane epoxy resins, alicyclic epoxy resins, aliphatic chain epoxy resins, phosphorus-containing epoxy resins, anthracene epoxy resins, norbornene epoxy resins, adamantane epoxy resins, fluorene epoxy resins, aminophenol epoxy resins, aminocresol epoxy resins, and alkylphenol epoxy resins. These epoxy resins may be used alone or in combination of two or more. Among these polyfunctional epoxy resins, from the viewpoint of further exhibiting the effects of the present invention, phenol novolac-type epoxy resins and cresol novolac-type epoxy resins are preferred, and cresol novolac-type epoxy resins are more preferred.

[0047] Examples of dibasic acid anhydrides used to synthesize epoxy-modified acrylic resins include phthalic anhydride, tetrahydrophthalic anhydride, and hexahydrophthalic anhydride. These epoxy resins can be used alone or in combination of two or more. From the perspective of further enhancing the effects of the present invention, tetrahydrophthalic anhydride is preferred.

[0048] Therefore, from the perspective of further exerting the effects of the present invention, epoxy-modified acrylic resins obtained by reacting a phenol novolac epoxy resin or a cresol novolac epoxy resin with (meth)acrylic acid and adding tetrahydrophthalic anhydride to the hydroxyl groups present in the side chains are more preferred. From the perspective of minimizing residue after exposure and development, epoxy-modified acrylic resins obtained by reacting a phenol novolac epoxy resin with acrylic acid and adding tetrahydrophthalic anhydride to the hydroxyl groups present in the side chains are particularly preferred. From the same perspective, epoxy-modified acrylic resins obtained by further adding glycidyl (meth)acrylate to these epoxy-modified acrylic resins are also preferred.

[0049] As the epoxy-modified acrylic resin (A), a commercial product or a synthetic product may be used. Specific examples of the synthetic product include the following compounds:

[0050] (1) A carboxyl group-containing resin obtained by reacting a polyfunctional epoxy resin with (meth)acrylic acid and adding a dibasic acid anhydride such as phthalic anhydride, tetrahydrophthalic anhydride, or hexahydrophthalic anhydride to the hydroxyl groups present in the side chains.

[0051] (2) A carboxyl group-containing resin obtained by reacting a polyfunctional epoxy resin obtained by epoxidizing the hydroxyl groups of a bifunctional epoxy resin with epichlorohydrin with (meth)acrylic acid and adding a dibasic acid anhydride to the generated hydroxyl groups.

[0052] (3) A carboxyl group-containing resin obtained by further adding a compound having one epoxy group and one or more (meth)acryloyl groups in the molecule, such as glycidyl (meth)acrylate, α-methylglycidyl (meth)acrylate, or 3,4-epoxycyclohexylmethyl methacrylate, to the carboxyl group-containing resin described in (1) or (2) above.

[0053] From the perspective of being more conducive to solving the technical problems of the present invention, the above-mentioned (1) type (A) epoxy-modified acrylic resin is preferred, among which the carboxyl-containing resin obtained by reacting a multifunctional epoxy resin with an unsaturated monocarboxylic acid and reacting a saturated or unsaturated polyacid anhydride with the generated hydroxyl group is more preferred.

[0054] The weight average molecular weight of the epoxy-modified acrylic resin (A) is generally preferably 2,000 to 150,000, more preferably 3,000 to 30,000, even more preferably 4,000 to 15,000, and most preferably 6,000 to 10,000. A weight average molecular weight of 2,000 or greater provides good resolution. On the other hand, a weight average molecular weight of 150,000 or less provides good developability.

[0055] The amount of the epoxy-modified acrylic resin (A) blended is preferably 50-90% by mass, more preferably 60-80% by mass, relative to the total mass of the epoxy-modified acrylic resin (A) and the copolymerized acrylic resin (B) in terms of solid content. When the amount of the epoxy-modified acrylic resin (A) blended is within this range, the plating resist composition exhibits moderate viscosity, improved coating properties, and excellent plating resist performance. In particular, a blending amount within the range of 60-80% by mass can further reduce the amount of residual carbon after development.

[0056] (B) Copolymerized acrylic resin

[0057] The (B) copolymerized acrylic resin is a copolymerized resin having a carboxyl group obtained by reacting (a) a carboxyl group-containing (meth)acrylic copolymerized resin with (b) a compound having an ethylene oxide ring and an ethylenically unsaturated group in one molecule.

[0058] The carboxyl group-containing (meth)acrylic copolymer resin (a) is obtained by copolymerizing a (meth)acrylate with a compound having one unsaturated group and at least one carboxyl group in one molecule. Examples of the (meth)acrylate constituting the carboxyl group-containing (meth)acrylic copolymer resin (a) include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, and hexyl (meth)acrylate; hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, and caprolactone-modified 2-hydroxyethyl (meth)acrylate; and glycol-modified (meth)acrylates such as methoxydiethylene glycol (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, isooctyloxydiethylene glycol (meth)acrylate, phenoxytriethylene glycol (meth)acrylate, methoxytriethylene glycol (meth)acrylate, and methoxypolyethylene glycol (meth)acrylate. These may be used alone or in combination of two or more.

[0059] Examples of the compound having one unsaturated group and at least one carboxyl group in one molecule include acrylic acid, methacrylic acid, modified unsaturated monocarboxylic acids in which the unsaturated group and the carboxylic acid are chain-extended, such as β-carboxyethyl (meth)acrylate, 2-acryloyloxyethylsuccinic acid, 2-acryloyloxyethylhexahydrophthalic acid, unsaturated monocarboxylic acids having an ester bond by lactone modification, modified unsaturated monocarboxylic acids having an ether bond, and substances containing two or more carboxyl groups in the molecule such as maleic acid. These compounds may be used alone or as a mixture of two or more.

[0060] As the compound (b) having an ethylene oxide ring and an ethylenically unsaturated group in one molecule, any compound having an ethylene oxide ring and an ethylene oxide ring in one molecule may be used, and examples thereof include glycidyl (meth)acrylate, α-methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxycyclohexylethyl (meth)acrylate, 3,4-epoxycyclohexylbutyl (meth)acrylate, and 3,4-epoxycyclohexylmethylaminoacrylate. Among them, 3,4-epoxycyclohexylmethyl (meth)acrylate is preferred. These (e) compounds having an ethylene oxide ring and an ethylenically unsaturated group in one molecule may be used alone or in combination of two or more.

[0061] From the viewpoints of electroplating copper resistance and acid resistance, the acid value of the copolymerized acrylic resin (B) is preferably 40 to 130 mgKOH / g, more preferably 50 to 120 mgKOH / g. The weight-average molecular weight of the copolymerized acrylic resin (B) is generally preferably 10,000 to 50,000, more preferably 15,000 to 40,000, further preferably 18,000 to 30,000, and most preferably 22,000 to 28,000.

[0062] The amount of the copolymerized acrylic resin (B) is 10 to 50% by mass, preferably 20 to 40% by mass, relative to the total mass of the epoxy-modified acrylic resin (A) and the copolymerized acrylic resin (B) in terms of solid content. When the amount of the copolymerized acrylic resin (B) is within this range, the cured film of the plating resist composition exhibits excellent resolution and good plating resistance. If the amount is less than 10% by mass, the residual carbon content during development increases. If the amount is greater than 50% by mass, the resolution and plating resistance are adversely affected.

[0063] (C) Multifunctional acrylic monomer

[0064] The polyfunctional acrylic monomer (C) contained in the plating resist composition of the present invention is a compound having multiple (meth)acryloyl groups in its molecule. The polyfunctional acrylic monomer (C) is photocured by irradiation with active energy rays, thereby rendering the plating resist composition of the present invention insoluble in an alkaline aqueous solution or contributing to rendering the plating resist composition of the present invention insoluble in an alkaline aqueous solution.

[0065] Examples of such (C) multifunctional acrylic monomers include diacrylates of diols such as ethylene glycol, methoxytetraethylene glycol, polyethylene glycol, propylene glycol, and hexylene glycol; polyacrylates of polyols such as trimethylolpropane, pentaerythritol, dipentaerythritol, and trishydroxyethyl isocyanurate, or their ethylene oxide adducts or propylene oxide adducts; polyacrylates of phenoxyacrylate, bisphenol A diacrylate, and ethylene oxide adducts or propylene oxide adducts of these phenols; polyacrylates of glycidyl ethers such as glycerol diglycidyl ether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, and triglycidyl isocyanurate; and melamine acrylates, and / or methacrylates corresponding to the above-mentioned acrylates.

[0066] Furthermore, examples include: epoxy acrylate resins obtained by reacting a multifunctional epoxy resin such as a cresol novolac epoxy resin with acrylic acid (such epoxy acrylate resins do not include those belonging to the above-mentioned (A) epoxy-modified acrylic resin); and epoxy urethane acrylate compounds obtained by further reacting the hydroxyl group of the epoxy acrylate resin with a half-urethane compound (obtained by reacting a hydroxy acrylate such as pentaerythritol triacrylate with a diisocyanate such as isophorone diisocyanate).

[0067] These (C) polyfunctional acrylic monomers can be used alone or in combination of two or more.

[0068] From the viewpoint of achieving the effects of the present invention, it is preferred to include a trifunctional or higher acrylic monomer. Furthermore, from the viewpoint of improving resolution and plating resistance, it is more preferred to include a tetrafunctional or higher acrylic monomer, and even more preferred to include a pentafunctional or higher acrylic monomer.

[0069] The amount of the multifunctional acrylic monomer (C) is preferably 12 to 35 parts by mass, more preferably 15 to 30 parts by mass, relative to 100 parts by mass of the total solids content of the epoxy-modified acrylic resin (A) and the copolymerized acrylic resin (B). Including the multifunctional acrylic monomer (C) in this amount can provide the plating resist composition with superior plating resistance and developability, further suppressing development residue and cell surface scratches.

[0070] If the amount of the multifunctional acrylic monomer (C) exceeds 35 parts by mass, the content of the epoxy-modified acrylic resin (A) becomes relatively low, the photocurability and developability during exposure decrease, the resolution may become poor, and satisfactory plating resistance is difficult to obtain. In addition, there is a tendency for the residual carbon content after exposure and development to increase. If the amount is less than 12 parts by mass, it is difficult to improve the photocurability, and it is difficult to form a pattern by alkaline development after active energy ray irradiation, resulting in poor resolution and poor copper plating resistance. From the viewpoint of further exerting the effects of the present invention, the amount is more preferably 15 to 30 parts by mass.

[0071] The molecular weight of the polyfunctional acrylic monomer (C) is generally preferably 200 to 3000, more preferably 250 to 2000, and even more preferably 300 to 1000. A weight average molecular weight of 200 or greater provides good resolution. On the other hand, a weight average molecular weight of 3000 or less provides good developability.

[0072] Examples of commercially available (C) multifunctional acrylic monomers include MT3501A (a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, manufactured by Zhangjiagang DIC Chemical Co., Ltd.).

[0073] (D) Photopolymerization initiator

[0074] The (D) photopolymerization initiator contained in the plating resist composition of the present invention comprises an acylphosphine oxide-based photopolymerization initiator. In addition, the plating resist composition of the present invention may further contain a photopolymerization initiator other than the acylphosphine oxide-based photopolymerization initiator.

[0075] As photopolymerization initiators other than the acylphosphine oxide-based photopolymerization initiators, known substances suitable for use in electroplating resist compositions can be used, for example: benzoin and its alkyl ethers such as benzoin, benzoin methyl ether, and benzoin ethyl ether; acetophenones such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, and 4-(1-tert-butyldioxy-1-methylethyl)acetophenone; 2-methylanthraquinone, 2-amylanthraquinone, 2-tert-butylanthraquinone, Anthraquinones such as 1-chloroanthraquinone; thioxanthones such as isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, and 2-chlorothioxanthone; ketals such as acetophenone dimethyl ketal and benzil dimethyl ketal; benzophenones such as benzophenone, 4-(1-tert-butyldioxy-1-methylethyl)benzophenone, 3,3',4,4'-tetrakis(tert-butyldioxycarbonyl)benzophenone, and 4,4'-bis(diethylamino)benzophenone; and xanthones, etc.

[0076] In addition, as the (D) photopolymerization initiator, oxime ester-based photopolymerization initiators having an oxime ester group, alkylphenone-based photopolymerization initiators, α-aminoacetophenone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, titanocene-based photopolymerization initiators, phosphate-based photopolymerization initiators, etc. can also be used.

[0077] Examples of commercially available benzophenone-based photopolymerization initiators include EAB manufactured by BASF GmbH of Germany.

[0078] Examples of commercially available thioxanthone-based photopolymerization initiators include ITX manufactured by Hubei Gurun Technology Co., Ltd.

[0079] Commercially available oxime ester photopolymerization initiators include Irgacure OXE01 and Irgacure OXE02 manufactured by BASF Japan, and N-1919 and NCI-831 manufactured by ADEKA Corporation. Photopolymerization initiators having two oxime ester groups in the molecule are preferably used, and specifically, oxime ester compounds having a carbazole ring structure are exemplified.

[0080] Examples of commercially available alkylphenone-based photopolymerization initiators include α-hydroxyalkylphenone-based products such as Omnirad 184, Omnirad 1173, Omnirad 2959, and Omnirad 127 manufactured by IGM Resins BV.

[0081] Examples of the α-aminoacetophenone-based photopolymerization initiator include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, and commercially available products such as Omnirad 907 manufactured by IGM Resins BV.

[0082] Specific examples of the acylphosphine oxide-based photopolymerization initiators include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, and trifunctional or higher-functional acylphosphine-based photopolymerization initiators.

[0083] As commercially available products of the acylphosphine oxide-based photopolymerization initiator, Omnirad TPO manufactured by IGM Resins, Omnirad 819 and Omnipol TP manufactured by IGM Resins BV, etc. can be used.

[0084] Specific examples of the titanocene-based photopolymerization initiator include bis(cyclopentadienyl)-diphenyltitanium, bis(cyclopentadienyl)-titanium dichloride, bis(cyclopentadienyl)-bis(2,3,4,5,6-pentafluorophenyl)titanium, and bis(cyclopentadienyl)-bis(2,6-difluoro-3-(pyrrol-1-yl)phenyl)titanium. Commercially available products include Omnirad 784 manufactured by IGM Resins BV.

[0085] The photopolymerization initiator of the present invention preferably contains a benzophenone-based photopolymerization initiator, an α-aminoacetophenone-based photopolymerization initiator, a thioxanthone-based photopolymerization initiator, and an acylphosphine oxide-based photopolymerization initiator. The preferred mixing ratio of benzophenone-based photopolymerization initiator: thioxanthone-based photopolymerization initiator: α-aminoacetophenone-based photopolymerization initiator: acylphosphine oxide-based photopolymerization initiator is 1-3:1-3:10-20:2-10 by mass. Although the detailed mechanism is unclear, the inventors of the present invention have found that in order to take into account low carbon residue, good acid resistance and high adhesion to copper grid lines, acylphosphine oxide-based photopolymerization initiator is an essential initiator component. If the above-mentioned photopolymerization initiators are used in the above-mentioned mixing ratio, an anti-plating composition can be obtained whose cured film has high resolution, low carbon residue, good acid resistance and high adhesion to copper grid lines.

[0086] Without affecting the effects of the present invention, other types of photopolymerization initiators commonly used in the art, such as those mentioned above, may also be appropriately compounded.

[0087] The total amount of these photopolymerization initiators is suitably 0.01 to 30 parts by weight, preferably 5 to 25 parts by weight, relative to 100 parts by weight of the total solid content of the epoxy-modified acrylic resin (A) and the copolymerized acrylic resin (B). If the amount of the photopolymerization initiator used is less than the above range, the photocurability of the composition tends to deteriorate. On the other hand, if the amount is too high, the properties of the plating resist composition may be deteriorated, which is not preferred.

[0088] Other ingredients

[0089] The plating resist composition of the present invention may contain an inorganic filler, but preferably does not contain an inorganic filler from the viewpoint of reducing exposure and development residues. Moreover, the plating resist composition of the present invention has excellent plating resistance even without an inorganic filler.

[0090] The plating resist composition of the present invention may contain (E) a colorant, and a known and commonly used organic colorant may be used. It should be noted that the (E) colorant that may be contained in the plating resist composition of the present invention preferably does not include an inorganic filler.

[0091] Examples of the colorant (E) include perylene-based, phthalocyanine-based, anthraquinone-based, monoazo-based, disazo-based, azo lake-based, benzimidazolone-based, perylene-based, diketopyrrolopyrrole-based, condensed azo-based, anthraquinone-based, quinacridone-based, isoindolinone-based, and anthraquinone-based colorants.

[0092] Such (E) coloring agents may be used alone or in combination of two or more.

[0093] Furthermore, the plating resist composition of the present invention may contain (F) an organic solvent, which is used for preparation of the composition and adjustment of viscosity.

[0094] Examples of the organic solvent (F) include ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, and petroleum solvents. More specifically, the organic solvents include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; esters such as ethyl acetate, butyl acetate, diethylene glycol ethyl ether acetate, dipropylene glycol methyl ether acetate, propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, and propylene glycol butyl ether acetate; alcohols such as ethanol, propanol, ethylene glycol, and propylene glycol; aliphatic hydrocarbons such as octane and decane; and petroleum solvents such as petroleum ether, naphtha, hydrogenated naphtha, and solvent naphtha.

[0095] Such (F) organic solvents may be used alone or in combination of two or more.

[0096] In addition, the plating-resistant composition of the present invention may also be compounded with known and commonly used additives such as thermal polymerization inhibitors, thermal curing catalysts, ultraviolet absorbers, plasticizers, flame retardants, antistatic agents, antioxidants, volatile agents, antioxidants, antibacterial / antifungal agents, defoaming agents, leveling agents, anti-sag agents, thickeners, adhesion-imparting agents, thixotropy-imparting agents, photoinitiator aids, sensitizers, photobase generators, thermoplastic resins, elastomers, organic fillers, release agents, surface treatment agents, dispersants, dispersing aids, surface modifiers, stabilizers, phosphors, and cellulose resins as needed.

[0097] Among them, melamine is preferably added. As an antioxidant, it improves the adhesion between the substrate and the cured film of the thermosetting composition by inhibiting oxidation of the conductor (copper) on the substrate. As a thermosetting catalyst, it can improve the acid and alkali resistance, metal plating resistance, adhesion, and hardness of the dry film formed by the electroplating resist composition, the curing agent, etc.

[0098] The plating resist composition of the present invention may be in the form of a dry film including a carrier film (support) and a layer composed of the plating resist composition formed on the carrier film.

[0099] When forming a dry film, the plating resist composition of the present invention is diluted with the aforementioned organic solvent and adjusted to an appropriate viscosity. The composition is then applied to a carrier film in a uniform thickness using a notch wheel coater, a knife coater, a lip coater, a rod coater, an extrusion coater, a reverse coater, a transfer roll coater, a gravure coater, a spray coater, or the like. The composition is then dried, typically at a temperature of 50 to 130° C. for 1 to 30 minutes, to form a resin layer as a dried coating. The resin layer is not particularly limited and is generally selected within a range of 10 to 150 μm, preferably 20 to 60 μm, in terms of film thickness after drying.

[0100] As the carrier film, a plastic film is used, preferably a polyester film such as polyethylene terephthalate, a polyimide film, a polyamide-imide film, a polypropylene film, a polystyrene film, or the like. The thickness of the carrier film is not particularly limited, but is generally selected within the range of 10 to 150 μm.

[0101] In this case, after forming the resin layer on the carrier film, a removable cover film is preferably further laminated on the surface of the resin layer to prevent dust from adhering to the surface of the resin layer. Examples of the removable cover film include polyethylene film, polytetrafluoroethylene film, polypropylene film, and surface-treated paper. When the cover film is peeled off, the adhesion between the resin layer and the cover film should be smaller than the adhesion between the resin layer and the carrier film.

[0102] As a method for producing a solar cell electrode using the plating resist composition of the present invention or a dry film thereof, a known production method can be adopted.

[0103] For example, the anti-plating composition of the present invention can be adjusted to a viscosity suitable for the coating method as needed, and applied to the surface of a solar cell formed into a pyramid-shaped velvet by methods such as screen printing, curtain coating, spraying, and roller coating. The solvent contained in the composition is evaporated and dried at a temperature of, for example, 60 to 100° C. as needed to form a coating film. Alternatively, the dry film of the present invention is laminated to the surface of a solar cell formed into a pyramid-shaped velvet, and the carrier film is peeled off to form a layer formed by the anti-plating composition on the surface of the solar cell. Then, the photomask having a predetermined exposure pattern is selectively exposed by active energy ray irradiation, and the unexposed portion is developed at a temperature of, for example, about 30° C. with a developer such as 1 to 2% Na2CO3 or K2CO3 solution for, for example, 60 to 90 seconds to form an anti-plating mask having a predetermined exposure pattern. Electroplating is performed on the surface of the cell formed with the anti-plating mask, thereby forming a metal layer as an electrode on the surface of the cell at the pattern gap. Then, the anti-plating mask is stripped and removed by using NaOH or KOH solution at a temperature of 40 to 70° C., and then a solder layer is plated by PVD. After sintering, a solar cell module with electrodes is obtained.

[0104] Example

[0105] The embodiments of the present invention will be described in detail below with reference to the examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention. Where specific conditions are not specified in the examples, the methods were performed according to conventional conditions or the conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be obtained commercially.

[0106] In addition, unless otherwise specified, "parts" and "%" below are based on mass.

[0107] The plating resist compositions of Examples 1 to 15 and Comparative Examples 1 to 7 were obtained by mixing the components shown in Tables 1 and 2 at the indicated blending ratios (based on mass).

[0108]

Table 1

[0109]

Table 2

[0110] Remark:

[0111] *1 (A) Epoxy-modified acrylic resin: a cresol novolac-type epoxy-modified acrylic resin prepared in Synthesis Example 1, having a solid content of 64% and an acid value of 58 mgKOH / g

[0112] *2 (B) Copolymerized acrylate resin, acrylic copolymer prepared as follows in Synthesis Example 2, solid content 54%, acid value 109 mgKOH / g

[0113] *3(C) Multifunctional acrylic monomer, MT3501A, manufactured by Zhangjiagang DIC Chemical Co., Ltd., a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (solid content 100%)

[0114] *4 (E) Blue pigment, FASTOGEN BLUE FA5380, manufactured by DIC Corporation

[0115] *5 Silicone defoamer, KS-66, manufactured by Shin-Etsu Chemical Co., Ltd.

[0116] *6 Polymer defoamer, BYK-057, manufactured by BYK-CHEMIE GmbH

[0117] *7 Dispersant, BYK-110, manufactured by BYK-CHEMIE GmbH

[0118] *8(D) Photopolymerization initiator EAB, 4,4'-bis(diethylamino)benzophenone, manufactured by BASF, Germany

[0119] *9(D) Photopolymerization initiator, TPO, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, manufactured by IGM RESINS BV

[0120] *10(D) Photopolymerization initiator, Omnirad 369, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-1-butanone, manufactured by IGM RESINS BV

[0121] *11(D) Photopolymerization initiator, ITX, 4-isopropylthioxanthone, manufactured by Hubei Gurun Technology Co., Ltd.

[0122] *12(D) Photopolymerization initiator, Omnirad 907, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, manufactured by IGM RESINS BV

[0123] *13Melamine, made by Guangzhou Jiachun Electronics Co., Ltd.

[0124] *14(F) Solvent, carbitol acetate (CA), manufactured by Jiangsu Tianyin Chemical Co., Ltd.

[0125] Synthesis example 1

[0126] 950 parts of a phenol novolac-type epoxy resin (EPICLONN-770, manufactured by DIC Corporation, softening point 65-75°C, epoxy equivalent 190) (glycidyl group number (total number of aromatic rings): 5.0 mol), 360 parts of acrylic acid (5.0 mol), and 1.5 parts of hydroquinone were added to 650 parts of diethylene glycol monoethyl ether acetate, heated to 100°C, and stirred until uniformly dissolved. Next, 4.3 parts of triphenylphosphine were added, heated to 110°C, and reacted for 2 hours. An additional 1.6 parts of triphenylphosphine was then added, the temperature was raised to 120°C, and the reaction was continued for a further 12 hours. To the resulting reaction solution, 525 parts of an aromatic hydrocarbon (SOLVESSO 150) and 608 parts of tetrahydrophthalic anhydride (4.0 mol) were added, and the reaction was continued at 110°C for 4 hours. Furthermore, 770 parts (5.4 mol) of glycidyl methacrylate was added to the obtained reaction solution, and the reaction was carried out at 115° C. for 4 hours to obtain a phenol novolac type epoxy-modified acrylic resin solution having a solid content acid value of 58 mgKOH / g and a solid content of 64%.

[0127] Synthesis example 2

[0128] A 2-liter separable flask equipped with a stirrer, thermometer, reflux condenser, dropping funnel, and nitrogen inlet tube was charged with 900 g of diethylene glycol dimethyl ether as a solvent and 21.4 g of t-butyl peroxy-2-ethylhexanoate (PERBUTYL O, manufactured by NOF Corporation) as a polymerization initiator, and heated to 90°C. Following the addition, 309.9 g of methacrylic acid, 116.4 g of methyl methacrylate, and 109.8 g of lactone-modified 2-hydroxyethyl methacrylate (PLACCEL FM1, manufactured by DAICEL CHEMICAL INDUSTRIES, LTD.) were added dropwise over 3 hours along with 21.4 g of bis(4-t-butylcyclohexyl) peroxydicarbonate (PEROYL TCP, manufactured by NOF Corporation) as a polymerization initiator, and the mixture was aged for an additional 6 hours to obtain a carboxyl group-containing copolymer resin. The reaction was carried out under a nitrogen atmosphere.

[0129] Next, 363.9 g of 3,4-epoxycyclohexyl methacrylate (Cyclomer A200, manufactured by DAICEL CHEMICAL INDUSTRIES, LTD.), 3.6 g of dimethylbenzylamine as a ring-opening catalyst, and 1.80 g of hydroquinone monomethyl ether as a polymerization inhibitor were added to the resulting carboxyl copolymer resin. The mixture was heated to 100° C. and stirred to effect an epoxy ring-opening addition reaction. After 16 hours, a solution containing 54% by mass (solids content) of an aromatic-free carboxyl resin was obtained. The solid content of the resin had an acid value of 109 mgKOH / g and a weight-average molecular weight of 25,000.

[0130] The plating resist compositions obtained in Examples 1 to 15 and Comparative Examples 1 to 7 were subjected to the following performance evaluation.

[0131] Evaluation methods and benchmarks

[0132] (1) Resolution evaluation

[0133] The electroplating resist compositions of the above-mentioned embodiments and comparative examples were applied to the entire surface of the solar cell, dried at 80°C for 15 minutes, and cooled to room temperature to form a resin layer with a thickness of 10 μm. For the upper surface (exposed surface) of the dried composition, a DI exposure machine (Ledia6 manufactured by SCREEN Corporation) was used to expose a pattern design with line / space of 10 μm / 10 μm, 20 μm / 20 μm, 30 μm / 30 μm, 40 μm / 40 μm, 50 μm / 50 μm, 60 μm / 60 μm, 70 μm / 70 μm, 80 μm / 80 μm, 90 μm / 90 μm, 100 μm / 100 μm, and 200 μm / 200 μm, with a 405 nm light source output of 100% and a radiant energy of 400 mJ / cm 2 The film was exposed at an exposure dose of 1000 nm and developed using a 1 mass % sodium carbonate aqueous solution at 30° C. under a spray pressure of 2 kg for 60 seconds to obtain an evaluation substrate.

[0134] The minimum designed line width remaining on the substrate was visually confirmed and recorded in Tables 1 and 2 as the evaluation of resolution.

[0135] (2) Evaluation of development residue

[0136] The resist plating composition of the above embodiment and comparative example was applied to the entire surface of the solar cell, dried at 80°C for 20 minutes, and then placed at 20°C for 10 minutes to form a resin layer with a thickness of 10 μm. The upper surface (exposed surface) of the dried composition was exposed using a DI exposure machine (Ledia6 manufactured by SCREEN) with a 405 nm light source output power of 100% and a 400 mJ / cm 2 The pattern was exposed with an exposure dose of 1000 nm, and developed using a 1 mass % sodium carbonate aqueous solution at 30° C. and a spray pressure of 2 kg for 60 seconds to obtain an evaluation substrate.

[0137] The surface of the substrate after development was inspected using an EDS element detector: Hitachi SU3500 EDS: Thermo UltraDry 5225 (sample Pt pretreatment). The carbon residue content was determined by the carbon content. The exposure and development residue of the above composition was evaluated based on the carbon content. The evaluation criteria are as follows.

[0138] C% is 0% or more and less than 5% ○

[0139] C% is 5% or more and less than 10% △

[0140] C% is 10% or more ×

[0141] (3) Evaluation of copper plating resistance (adhesion)

[0142] The evaluation substrate obtained in the above (2) was subjected to a copper electroplating process to evaluate the copper electroplating resistance.

[0143] In the copper electroplating process, the plating solution used is: copper sulfate (CuSO4·5H2O) 200g / L, sulfuric acid (H2SO4) 80g / L, chloride ion (Cl - )70mg / L, inhibitor 13ml / L, brightener 30ml / L, leveler 20ml / L. Electroplating operating conditions are: temperature 20-25℃, current density 5A / dm 2 , the stirring intensity is strong, and the electroplated copper thickness is 5 to 50 μm.

[0144] The evaluation items are: 1) whether there is any peeling of the plating resist composition on the surface of the cell after copper plating, and whether there is any cross-circuiting of the copper grid lines; 2) after the copper is plated, a 3M tape stress pull-off test is performed to see if the copper grid lines are peeling off.

[0145] The evaluation criteria are as follows:

[0146] After copper plating, there is no peeling of the resist composition on the surface of the cell, no cross-circuiting of the copper grid lines, and no peeling of the copper grid lines during the 3M tape stress pull-off test.

[0147] After copper plating, there is no peeling of the resist composition on the surface of the cell, and no copper grid cross-circuit. However, the copper grid is peeled off during the 3M tape stress pull-off test.

[0148] After copper plating, the surface of the cell is peeled off due to the resist composition, or there is a copper grid cross-circuit.

[0149] (4) Evaluation of fading (acid resistance)

[0150] The evaluation substrate obtained in the above (2) was evaluated for washability under the following conditions.

[0151] Sodium hydroxide 5 mass% solution is kept at 60℃ for 5 minutes

[0152] The evaluation criteria are as follows:

[0153] After soaking in the stripping solution, there is no residue on the surface of the substrate.

[0154] After soaking in the de-laundering liquid, there is a slight residue, and after washing with water, there is no residue.

[0155] After soaking in the degreasing solution, there is a residue, and after washing with water, there is still a residue ×

[0156] The results of the aforementioned evaluation tests are collectively shown in Tables 1 and 2 above.

[0157] As shown in Tables 1 and 2, Examples 1-4, which contain both (A) an epoxy-modified acrylic resin and 10-40% by mass of (B) a copolymerized acrylate resin, but do not contain Omnirad 369, exhibit superior results in resolution, development residue, and washout performance compared to Comparative Example 1, which does not contain (B) a copolymerized acrylate resin and also does not contain Omnirad 369. Examples 1-4 also exhibit superior results in resolution, development residue, and electroplating copper resistance compared to Comparative Examples 5-7, which contain a higher content of (B) a copolymerized acrylate resin and also do not contain Omnirad 369. While Example 1 exhibits slightly higher development residue than Comparative Example 2, which does not use TPO but uses Omnirad 369, it exhibits significantly superior resolution and electroplating copper resistance.

[0158] In addition, as can be seen from Examples 1 to 4, Examples 5 to 8, and Examples 9, 10, and 12, as the content of the copolymerized acrylate resin (B) further increases, there is a tendency for the development residue to improve but the resolution to decrease (i.e., the residual minimum design line width increases). A comparison between Examples 1, 5, and 9, between Examples 2, 6, and 10, between Examples 3, 7, and 11, and between Examples 4, 8, and 12 shows that as the content of the multifunctional acrylic monomer (C) decreases, there is a tendency for the development residue to improve but the resolution to decrease. Furthermore, a comparison between Example 11 and Examples 13 to 15 shows that when the content of the copolymerized acrylate resin (B) is further increased to the same amount as the epoxy acrylic modified resin (A), there is a tendency for the resolution and electroplating copper resistance to deteriorate, and the development residue is not further improved. Furthermore, in Comparative Examples 3 and 4, although the development residue and washability are excellent when the content of the multifunctional acrylic monomer (C) is further reduced, the resolution and electroplating copper resistance are poor due to the excessive content of the copolymerized acrylate resin (B).

[0159] These results indicate that the plating resist composition of the present invention has high resolution, little development residue, excellent resistance to copper plating and excellent washability, and is suitable for use as a plating resist ink in the manufacture of solar cell electrodes.

[0160] It should be noted that, although the technical solutions of the present invention are described with specific examples, those skilled in the art will appreciate that the present invention should not be limited thereto.

[0161] While various embodiments of the present invention have been described above, the above descriptions are intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or technological improvements in the marketplace, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A plating resistance composition, characterized in that: The invention comprises (A) an epoxy-modified acrylic resin, (B) a copolymerized acrylic resin, (C) a multifunctional acrylic monomer and (D) a photopolymerization initiator, wherein the (B) copolymerized acrylic resin accounts for 10 to 50% by weight relative to the total weight of the (A) epoxy-modified acrylic resin and the (B) copolymerized acrylic resin in terms of solid content, and the (D) photopolymerization initiator comprises an acylphosphine oxide-based photopolymerization initiator.

2. The plating resist composition according to claim 1, characterized in that: The (A) epoxy-modified acrylic resin is at least one of the following resins: Releasing a multifunctional epoxy resin with an unsaturated monocarboxylic acid, and reacting a saturated or unsaturated polyacid anhydride with the generated hydroxyl group to obtain a carboxyl group-containing resin; and A carboxyl group-containing resin is obtained by reacting a polyfunctional epoxy resin with an unsaturated monocarboxylic acid and reacting a saturated or unsaturated polyacid anhydride with the generated hydroxyl group, and a compound having one epoxy group and one or more (meth)acryloyl groups in the molecule is further added to the resin.

3. The anti-plating composition according to claim 1 or 2, characterized in that: The (B) copolymerized acrylic resin is a copolymerized resin having a carboxyl group obtained by reacting (a) a carboxyl group-containing (meth)acrylic copolymerized resin with (b) a compound having an oxirane ring and an ethylenically unsaturated group in one molecule.

4. The anti-plating composition according to claim 3, characterized in that: The amount of the (C) polyfunctional acrylic monomer is 12 to 35 parts by mass based on 100 parts by mass of the total mass of the (A) epoxy-modified acrylic resin and the (B) copolymerized acrylic resin in terms of solid content.

5. The plating-resistant composition according to claim 1 or 2, characterized in that: The (D) photopolymerization initiator further includes a benzophenone-based photopolymerization initiator, an α-aminoacetophenone-based photopolymerization initiator, and a thioxanthone-based photopolymerization initiator.

6. Use of the plating resist composition according to any one of claims 1 to 5 for producing an electrode for a solar cell.

7. A dry film, characterized in that: The plating resist composition according to any one of claims 1 to 5 is applied on a carrier film and dried.

8. A solidified product, characterized in that: This is obtained by curing the plating resist composition according to any one of claims 1 to 5.

9. A solidified product, characterized in that: This is obtained by curing the resin layer of the dry film according to claim 7.

10. An electrode for a solar cell, characterized in that: A cured product according to claim 8 or 9.

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