A yellowing-resistant solder resist ink based on alicyclic epoxy resin and a preparation method thereof

Abstract

The present invention provides a yellowing-resistant solder mask ink based on an alicyclic epoxy resin and a preparation method thereof. The ink comprises component A and component B. Component A comprises the following ingredients: an acrylic resin emulsion, a modified acrylic resin, a reactive monomer, a photoinitiator, an amino-modified filler, a pigment, an additive, and a solvent; and component B comprises the following ingredients in parts by weight: an alicyclic epoxy resin, an additive, and a solvent. The modified acrylic resin is obtained by reacting a multifunctional epoxy resin, acrylic acid, and an acrylate. This invention not only exhibits excellent yellowing resistance but also combines the advantages of alicyclic and aromatic ring structures to improve ink stability, adhesion, toughness, and other properties. This overcomes the shortcomings of existing technologies and provides new insights for the development of solder mask inks.

Description

Technical Field

[0001] The present invention relates to the field of solder resist inks, and in particular to a yellowing-resistant solder resist ink based on alicyclic epoxy resin and a preparation method thereof. Background Art

[0002] Epoxy resin is one of the main components of solder mask ink. When combined with curing agents, pigments, fillers, and other materials, it forms a highly hard, chemically resistant, and insulating solder mask layer, preventing solder bridging during soldering and protecting circuits. Cycloaliphatic epoxy resins are highly reactive and cure faster than traditional bisphenol A epoxy resins, resulting in polymers with higher molecular weights and lower shrinkage, making them more suitable for high-precision printing. Solder mask inks based on cycloaliphatic epoxy resins have found widespread application in high-end applications such as PCB manufacturing and LED lighting, and demand continues to grow with the advancement of UV curing technology.

[0003] Conventional epoxy resin-based inks still have some problems. For example, the benzene ring structure in o-cresol epoxy resin or bisphenol A epoxy resin easily generates free radicals under ultraviolet radiation, forming chromophores, which cause the ink to yellow, especially in white ink. Using alicyclic epoxy resins as an alternative can effectively avoid these problems, but these resins still have the disadvantages of poor toughness and insufficient stability. Their reliability in high-temperature and corrosive environments is also less than ideal, which has hindered the further promotion and application of such products.

[0004] In summary, there is an urgent need to develop a new technical solution to solve the problems existing in the existing technology. Summary of the Invention

[0005] The present invention provides an alicyclic epoxy resin-based anti-yellowing solder resist ink and a preparation method thereof. The alicyclic epoxy resin-based anti-yellowing solder resist ink is composed of components such as a modified acrylic resin, an amino-modified filler, and an alicyclic epoxy resin. It not only has good yellowing resistance, but also combines the advantages of alicyclic and aromatic ring structures, improves the ink's stability, adhesion, toughness, strength and other capabilities, overcomes the defects of the existing technology, and provides new ideas for the development of solder resist inks.

[0006] One object of the present invention is to provide a yellowing-resistant solder resist ink based on alicyclic epoxy resin, wherein the yellowing-resistant solder resist ink based on alicyclic epoxy resin comprises component A and component B.

[0007] The component A comprises the following components in parts by mass:

[0008]

[0009]

[0010] The component B comprises the following components in parts by mass:

[0011] 1-10 parts of cycloaliphatic epoxy resin

[0012] 1-10 parts of additives

[0013] 1-10 parts of solvent;

[0014] in,

[0015] The modified acrylic resin is obtained by reacting multifunctional epoxy resin, acrylic acid and acrylate.

[0016] Furthermore, the amino-modified filler is obtained by reacting an aminosilane coupling agent oligomer with boron nitride.

[0017] Preferably, the aminosilane coupling agent is KH-550.

[0018] Furthermore, the active monomer is an acrylate having a monofunctional group or a multifunctional group.

[0019] Furthermore, the acrylate includes alkyl acrylate, hydroxyalkyl acrylate, aminoalkyl acrylate and polyethylene glycol acrylate.

[0020] Furthermore, the alicyclic epoxy resin is a multifunctional alicyclic epoxy resin.

[0021] Preferably, the alicyclic epoxy resin is 4,5-epoxytetrahydrophthalic acid diglycidyl ester (CAS No.: 25293-64-5)

[0022] Furthermore, the acrylic resin emulsion is a carboxyl-containing acrylic resin emulsion.

[0023] Furthermore, the multifunctional epoxy resin is AG-80 epoxy resin (tetraglycidyldiaminodiphenylmethane).

[0024] Furthermore, the preparation method of the yellowing-resistant solder resist ink based on alicyclic epoxy resin comprises the following steps:

[0025] S1, mixing a multifunctional epoxy resin, acrylic acid and a polymerization inhibitor, and heating the mixture to react to obtain an intermediate product;

[0026] S2, mixing the intermediate product, acrylate, emulsifier and initiator, and heating the mixture to react to obtain a modified acrylic resin;

[0027] S3. Mixing acrylic resin emulsion, modified acrylic resin, active monomer, photoinitiator, amino-modified filler, pigment, additive and solvent to obtain component A; mixing alicyclic epoxy resin, additive and solvent to obtain component B; then mixing component A and component B to obtain yellowing-resistant solder resist ink based on alicyclic epoxy resin.

[0028] Furthermore, in step S1, the mass ratio of the multifunctional epoxy resin to acrylic acid is (1.4-1.6):1.

[0029] Furthermore, in step S1, the temperature of the heating reaction is 80-100°C.

[0030] Furthermore, in step S2, the acrylate is alkyl acrylate, hydroxyalkyl acrylate, aminoalkyl acrylate and polyethylene glycol acrylate in a mass ratio of (3-5):(3-5):(3-5):(1-3).

[0031] Furthermore, in step S2, the temperature of the heating reaction is 50-90°C.

[0032] The present invention has the following beneficial effects:

[0033] The present invention provides a yellowing-resistant solder mask ink based on alicyclic epoxy resin, comprising a modified acrylic resin, an amino-modified filler, an alicyclic epoxy resin and other components. The modified acrylic resin is a tetrafunctional epoxy resin that first undergoes a ring-opening reaction with acrylic acid to obtain an intermediate product having multiple double bonds, and then undergoes a polymerization reaction with n-butyl acrylate, hydroxyethyl acrylate, dimethylaminoethyl acrylate, and polyethylene glycol acrylate. On the one hand, the modified acrylic resin has both hydrophilic and hydrophobic groups, and thus has a certain surface activity, which improves the stability of the ink, can make the components more stably dispersed, and helps to improve the surface morphology of the film layer during curing and film formation; on the other hand, the component contains a large number of active functional groups, which can improve the adhesion of the ink to the substrate, and the amino and hydroxyl groups therein can also cross-link with the alicyclic epoxy resin, thereby introducing the branched structure of the intermediate product into the ink coating, further improving the stability and strength of the product.

[0034] The present invention also uses aminosilane coupling agent oligomers to modify the filler, thereby improving the compatibility between the filler and the organic resin and introducing a higher density of amino groups, so that it can be more fully cross-linked with components such as epoxy resin and acrylic resin to obtain a more three-dimensional and stable structure. Synergistic enhancement is achieved through multiple components, thereby improving the comprehensive performance of the solder mask ink.

[0035] In addition, the active groups in the various components of the present invention can also interact with each other through hydrogen bonds, which has a promoting effect on the stability of the pigment, thereby giving the product better yellowing resistance on the basis of the alicyclic epoxy resin, and also improving the corrosion resistance and acid and alkali resistance of the solder mask ink layer. DETAILED DESCRIPTION

[0036] In order to more clearly illustrate the technical solutions of the present invention, the following examples are given. Unless otherwise stated, the raw materials, reactions and post-processing methods mentioned in the examples are common raw materials on the market and technical methods well known to those skilled in the art.

[0037] The terms "preferred," "preferably," "more preferred," and the like, used herein, refer to embodiments of the invention that may provide certain benefits under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the invention.

[0038] It should be understood that, except in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and appended claims are approximations that may vary depending upon the desired properties to be obtained by the present invention.

[0039] The acrylic resin emulsion in the embodiment of the present invention is Sartomer SB520A20, and the acid value is 200 mgKOH / g (content 80%).

[0040] The active monomer in the embodiment of the present invention is methyl acrylate.

[0041] The photoinitiator in the embodiment of the present invention is ITX and UVI-6976 in a mass ratio of 1:1.

[0042] The pigment in the embodiment of the present invention is titanium dioxide.

[0043] The auxiliary agent in the embodiment of the present invention is the leveling agent isopropyl alcohol.

[0044] The solvent in the embodiment of the present invention is a divalent acid ester.

[0045] The alicyclic epoxy resin in the embodiment of the present invention is 4,5-epoxytetrahydrophthalic acid diglycidyl ester.

[0046] The polymerization inhibitor in the embodiment of the present invention is p-hydroxyanisole; the emulsifier is OP-10, purchased from Aladdin; and the initiator 1 and the initiator 2 are ammonium persulfate.

[0047] The polyethylene glycol methacrylate M in the embodiment of the present invention W =300, purchased from Sigma Aldrich.

[0048] The preparation method of the amino-modified filler in the embodiment of the present invention comprises the following steps:

[0049] 110 parts of ethanol and 110 parts of KH-550 were mixed, and a mixture of 8 parts of deionized water and 34 parts of ethanol was added dropwise under a nitrogen atmosphere. The mixture was stirred at 20°C for 2 hours, and then heated to 80°C for reflux reaction for 2 hours. The solvent was removed by distillation under reduced pressure to obtain a silane coupling agent oligomer.

[0050] 100 parts of deionized water were used as solvent, 10 parts of boron nitride and 5 parts of the silane coupling agent oligomer were added, the mixture was stirred at 70° C. for 6 hours, and the mixture was filtered and dried to obtain an amino-modified filler.

[0051] The “parts” in the embodiments of the present invention refer to parts by mass.

[0052] Example 1

[0053] A yellowing-resistant solder resist ink based on an alicyclic epoxy resin, comprising component A and component B.

[0054] The component A comprises the following components in parts by mass:

[0055]

[0056] The component B comprises the following components in parts by mass:

[0057] 6 parts of cycloaliphatic epoxy resin

[0058] 2 parts of additives

[0059] 5 parts solvent.

[0060] The preparation method of the yellowing-resistant solder resist ink based on alicyclic epoxy resin comprises the following steps:

[0061] S1. Using 20 parts of DMF as solvent, 1.5 parts of AG-80 epoxy resin, 1 part of acrylic acid and 0.03 parts of polymerization inhibitor were mixed, reacted at 90°C for 4 hours, and the solvent was removed and dried to obtain an intermediate product;

[0062] S2, using 60 parts of water as a solvent, mixing the intermediate product with 5 parts of n-butyl methacrylate, 0.6 parts of an emulsifier, and 0.1 parts of initiator 1, reacting at 60° C. for 2 h under a nitrogen atmosphere, then adding 5 parts of hydroxyethyl methacrylate, 5 parts of dimethylaminoethyl methacrylate, 2 parts of polyethylene glycol methacrylate, and 0.3 parts of initiator 2, continuing the reaction for 12 h, removing the solvent, and drying to obtain a modified acrylic resin;

[0063] S3. According to the above-mentioned parts by mass, the acrylic resin emulsion, the modified acrylic resin, the active monomer, the photoinitiator, the amino-modified filler, the pigment, the additive and the solvent are mixed to obtain component A; the alicyclic epoxy resin, the additive and the solvent are mixed to obtain component B; then the components A and B are mixed, stirred and dispersed evenly, and then ground to a fineness of ≤20 μm and passed through a 120-mesh sieve to obtain a yellowing-resistant solder resist ink based on alicyclic epoxy resin.

[0064] Example 2

[0065] A yellowing-resistant solder resist ink based on an alicyclic epoxy resin, comprising component A and component B.

[0066] The component A comprises the following components in parts by mass:

[0067]

[0068] The component B comprises the following components in parts by mass:

[0069] 8 parts of cycloaliphatic epoxy resin

[0070] 3 parts of additives

[0071] 7 parts solvent.

[0072] The preparation method of the yellowing-resistant solder resist ink based on alicyclic epoxy resin comprises the following steps:

[0073] S1. Using 20 parts of DMF as solvent, 1.5 parts of AG-80 epoxy resin, 1 part of acrylic acid and 0.03 parts of polymerization inhibitor were mixed, reacted at 90°C for 4 hours, and the solvent was removed and dried to obtain an intermediate product;

[0074] S2, using 60 parts of water as a solvent, mixing the intermediate product with 5 parts of n-butyl methacrylate, 0.6 parts of an emulsifier, and 0.1 parts of initiator 1, reacting at 60° C. for 2 h under a nitrogen atmosphere, then adding 5 parts of hydroxyethyl methacrylate, 5 parts of dimethylaminoethyl methacrylate, 2 parts of polyethylene glycol methacrylate, and 0.3 parts of initiator 2, continuing the reaction for 12 h, removing the solvent, and drying to obtain a modified acrylic resin;

[0075] S3. According to the above-mentioned parts by mass, the acrylic resin emulsion, the modified acrylic resin, the active monomer, the photoinitiator, the amino-modified filler, the pigment, the additive and the solvent are mixed to obtain component A; the alicyclic epoxy resin, the additive and the solvent are mixed to obtain component B; then the components A and B are mixed, stirred and dispersed evenly, and then ground to a fineness of ≤20 μm and passed through a 120-mesh sieve to obtain a yellowing-resistant solder resist ink based on alicyclic epoxy resin.

[0076] Example 3

[0077] A yellowing-resistant solder resist ink based on an alicyclic epoxy resin, comprising component A and component B.

[0078] The component A comprises the following components in parts by mass:

[0079]

[0080] The component B comprises the following components in parts by mass:

[0081] 10 parts of alicyclic epoxy resin

[0082] 4 parts of additives

[0083] 10 parts solvent.

[0084] The preparation method of the yellowing-resistant solder resist ink based on alicyclic epoxy resin comprises the following steps:

[0085] S1. Using 20 parts of DMF as solvent, 1.5 parts of AG-80 epoxy resin, 1 part of acrylic acid and 0.03 parts of polymerization inhibitor were mixed, reacted at 90°C for 4 hours, and the solvent was removed and dried to obtain an intermediate product;

[0086] S2, using 60 parts of water as a solvent, mixing the intermediate product with 5 parts of n-butyl methacrylate, 0.6 parts of an emulsifier, and 0.1 parts of initiator 1, reacting at 60° C. for 2 h under a nitrogen atmosphere, then adding 5 parts of hydroxyethyl methacrylate, 5 parts of dimethylaminoethyl methacrylate, 2 parts of polyethylene glycol methacrylate, and 0.3 parts of initiator 2, continuing the reaction for 12 h, removing the solvent, and drying to obtain a modified acrylic resin;

[0087] S3. According to the above-mentioned parts by mass, the acrylic resin emulsion, the modified acrylic resin, the active monomer, the photoinitiator, the amino-modified filler, the pigment, the additive and the solvent are mixed to obtain component A; the alicyclic epoxy resin, the additive and the solvent are mixed to obtain component B; then the components A and B are mixed, stirred and dispersed evenly, and then ground to a fineness of ≤20 μm and passed through a 120-mesh sieve to obtain a yellowing-resistant solder resist ink based on alicyclic epoxy resin.

[0088] Comparative Example 1

[0089] A yellowing-resistant solder resist ink based on alicyclic epoxy resin. The difference between this comparative example and Example 1 is that step S1 is deleted, and in step S2, the mass of the intermediate product is replaced by n-butyl methacrylate. The amounts of other components and the preparation method are the same as those in Example 1.

[0090] Comparative Example 2

[0091] A yellowing-resistant solder resist ink based on an alicyclic epoxy resin. This comparative example differs from Example 1 in that step S2 is modified as follows: using 60 parts of water as a solvent, the intermediate product, 15 parts of n-butyl methacrylate, 0.6 parts of an emulsifier, and 0.2 parts of an initiator 1 are mixed, the mixture is reacted at 60° C. under a nitrogen atmosphere for 12 hours, the solvent is removed, and the mixture is dried to obtain a modified acrylic resin; the amounts of other components and the preparation method are the same as those in Example 1.

[0092] Comparative Example 3

[0093] A yellowing-resistant solder resist ink based on an alicyclic epoxy resin. The difference between this comparative example and Example 1 is that the preparation method of the amino-modified filler is modified as follows: 100 parts of deionized water are used as a solvent, 10 parts of boron nitride and 5 parts of KH-550 are added, the mixture is stirred at 70°C for 6 hours, and the amino-modified filler is obtained by filtration and drying. The amounts of other components and the preparation method are the same as those in Example 1.

[0094] Test Case

[0095] The performance tests were conducted on the yellowing-resistant solder resist inks based on alicyclic epoxy resins prepared in Examples 1-3 and Comparative Examples 1-3.

[0096] The test method is as follows:

[0097] The yellowing-resistant solder resist inks based on alicyclic epoxy resin prepared in the examples and comparative examples were applied to PCB boards respectively and light-cured for 1 h (wavelength 395 nm, intensity 25.0 mW / cm 2 The film was then cured at 150°C for 1 hour to form a 0.7 mm thick film.

[0098] Adhesion: Use a needle to make an X-shape on the film. Then, apply cellophane tape to the cuts and pull. Evaluate based on the following criteria:

[0099] Qualified: not torn off;

[0100] Unqualified: A lot of tearing off.

[0101] Bending resistance: Bend the solder mask film 180° with the film facing outward and evaluate based on the following criteria:

[0102] Qualified: No cracks on the film;

[0103] Unqualified: There are cracks on the film.

[0104] Acid resistance: PCBs coated with yellowing-resistant solder resist ink based on alicyclic epoxy resin were immersed in a 10% sulfuric acid solution at 20°C. After 30 minutes, the coating condition and adhesion were evaluated. The criteria for determination were as follows:

[0105] Pass: No change or slight change was found;

[0106] Unqualified: There is swelling or shedding on the coating film.

[0107] Heat resistance: Thermal shock performance test is conducted according to the method in IPC-SM-840E. The judgment criteria are as follows:

[0108] Qualified: no bubbles or cracks;

[0109] Unqualified: bubbles and cracks appear.

[0110] Anti-yellowing performance: The reflectivity of the sample was measured after reflow soldering for three times. The reflow soldering conditions were: 190℃*3min, 220℃*2min, 240℃*3min, 280℃*4min, for a total of 12min.

[0111] The test instrument used is an X-RITE colorimeter model SP62. The larger the △B value, the more serious the yellowing.

[0112] The test results are shown in Table 1.

[0113] Table 1 Performance test results

[0114]

[0115] The above test results show that the yellowing-resistant solder mask ink based on the alicyclic epoxy resin prepared in the embodiment of the present invention has good adhesion, bending resistance, acid resistance, and heat resistance, and does not show obvious yellowing, meeting multiple performance requirements and having excellent overall performance. However, Comparative Examples 1 and 3, which replaced the intermediate product and amino-modified filler, failed to meet the mechanical performance requirements in the case of thicker ink films due to changes in the ink's network cross-linking structure and the degree of bonding between the components. They also showed insufficient bending resistance and reduced stability, resulting in more obvious yellowing. Comparative Example 2, due to the replacement of multiple acrylate monomers, significantly reduced the stability and strength of the ink composition, and suffered from severe yellowing, resulting in the worst overall performance.

[0116] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

[0117] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A yellowing-resistant solder resist ink based on alicyclic epoxy resin, characterized in that: The yellowing-resistant solder resist ink based on alicyclic epoxy resin comprises component A and component B. The component A comprises the following components in parts by mass: 10-30 parts of acrylic resin emulsion 10-20 parts of modified acrylic resin 20-40 parts of active monomer 1-2 parts of photoinitiator 20-30 parts of amino modified filler 3-9 parts pigment 1-5 parts of additives 40-60 parts of solvent; The component B comprises the following components in parts by mass: 1-10 parts of cycloaliphatic epoxy resin 1-10 parts of additives 1-10 parts of solvent; in; The method for preparing the yellowing-resistant solder resist ink based on alicyclic epoxy resin comprises the following steps: S1, mixing a multifunctional epoxy resin, acrylic acid and a polymerization inhibitor, and heating the mixture to react to obtain an intermediate product; S2, mixing the intermediate product, acrylate, emulsifier and initiator, and heating the mixture to react to obtain a modified acrylic resin; S3. Mixing an acrylic resin emulsion, a modified acrylic resin, an active monomer, a photoinitiator, an amino-modified filler, a pigment, an additive, and a solvent to obtain component A; mixing an alicyclic epoxy resin, an additive, and a solvent to obtain component B; and then mixing component A and component B to obtain a yellowing-resistant solder resist ink based on an alicyclic epoxy resin; In step S1, the mass ratio of the multifunctional epoxy resin to acrylic acid is (1.4-1.6):1; In step S2, the acrylate is an alkyl acrylate, a hydroxyalkyl acrylate, an aminoalkyl acrylate and a polyethylene glycol acrylate in a mass ratio of (3-5):(3-5):(3-5):(1-3); The active monomer is methyl acrylate; The photoinitiator is ITX and UVI-6976 in a mass ratio of 1:1; The pigment is titanium dioxide; The auxiliary agent is isopropyl alcohol, a leveling agent; The solvent is a divalent acid ester; The alicyclic epoxy resin is 4,5-epoxytetrahydrophthalic acid diglycidyl ester; The polymerization inhibitor is p-hydroxyanisole; the emulsifier is OP-10, purchased from Aladdin; the initiator is ammonium persulfate; The polyethylene glycol acrylate M W =300, purchased from Sigma Aldrich; The preparation method of the amino-modified filler comprises the following steps: 110 parts of ethanol and 110 parts of KH-550 were mixed, and a mixture of 8 parts of deionized water and 34 parts of ethanol was added dropwise under a nitrogen atmosphere. The mixture was stirred at 20°C for 2 hours, and then heated to 80°C for reflux reaction for 2 hours. The solvent was removed by distillation under reduced pressure to obtain a silane coupling agent oligomer. 100 parts of deionized water were used as solvent, 10 parts of boron nitride and 5 parts of the silane coupling agent oligomer were added, the mixture was stirred at 70° C. for 6 h, and the mixture was filtered and dried to obtain an amino-modified filler.

2. The yellowing-resistant solder resist ink based on alicyclic epoxy resin according to claim 1, characterized in that: In step S1, the temperature of the heating reaction is 80-100°C.

3. The yellowing-resistant solder resist ink based on alicyclic epoxy resin according to claim 1, characterized in that: In step S2, the temperature of the heating reaction is 50-90°C.

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