Epoxy resins and their applications

Abstract

This invention provides an epoxy resin that not only possesses outstanding storage stability but also demonstrates excellent processability in the manufacture of dielectrics for metal-clad laminates. [Solution] An epoxy resin represented by the following formula (I), In formula JPEG2026047038000007.jpg2595, each Ar is an arylene having one or more epoxy groups, each Ar may be the same or different, each R is a methylene, m1 and m2 are independent integers in the range of 0 to 4, n is greater than zero, and when the epoxy resin is characterized by gel permeation chromatography (GPC), the peak representing the region where n is less than 5 has a total area A, the peak representing the region where n is 5 or greater has a total area B, and the ratio of B to A (B / A) is 0.40 to 1.40, the epoxy resin.

Description

Technical Field

[0001] The present invention provides an epoxy resin, and particularly provides an epoxy resin having specific gel permeation chromatography (GPC) characteristics. Since the epoxy resin of the present invention has excellent storage stability and processability, it is particularly suitable for use in metal-clad laminates.

Background Art

[0002] A printed circuit board (PCB) can be used as a board for electronic devices, includes various electronic components that can be electronically connected to each other, and can provide a stable circuit operating environment. A general printed circuit board is a copper clad laminate (CCL).

[0003] Generally, a copper clad laminate can be manufactured by the following method: uniformly mixing a thermosetting resin (such as a phenol resin, an epoxy resin, etc.) and other additives, dissolving or dispersing them in a solvent to form a varnish; impregnating a reinforcing material (a glass fiber fabric) with the varnish, partially curing the impregnated reinforcing material to a semi-cured state (i.e., B-stage) to obtain a prepreg; stacking a certain number of layers of prepregs, stacking a metal foil on at least one outer surface of the stacked prepregs to provide a stacked object; and hot pressing the stacked object (i.e., C-stage) to obtain a copper clad laminate.

[0004] Examples of the thermosetting resins mentioned above include phenolic resins, epoxy resins, and others. Among these, epoxy resins are particularly widely used due to their excellent electrical insulation and heat resistance. However, in order to ensure the stability of copper-clad laminate quality, varnishes containing thermosetting resins must have excellent storage stability, meaning that phenomena such as crystallization and phase separation must not occur under long-term storage conditions. However, epoxy resins commonly face the problem of being prone to crystallization, resulting in insufficient storage stability. [Overview of the project] [Means for solving the problem]

[0005] From the above viewpoint, the present invention provides an epoxy resin that not only has outstanding storage stability but also demonstrates outstanding processability in the manufacture of dielectrics for metal-clad laminates. As a result, the manufactured metal-clad laminate is free from resin defects.

[0006] Therefore, the object of the present invention is an epoxy resin represented by the following formula (I), [ka] During the ceremony, Each Ar is an arylene having one or more epoxy groups, and each Ar may be the same or different. Each R is methylene, m1 and m2 are independent integers in the range of 0 to 4. n is greater than zero, The objective is to provide an epoxy resin characterized by gel permeation chromatography (GPC) such that when the epoxy resin is characterized, the peak representing the region where n is less than 5 has a total area A, the peak representing the region where n is 5 or greater has a total area B, and the ratio of B to A (B / A) is between 0.40 and 1.40.

[0007] In one embodiment of the present invention, each Ar is independently a divalent group derived from a phenol, cresol, m-benzenediol, or bisphenol compound, and is further epoxidized.

[0008] In one embodiment of the present invention, n is in the range of 1 to 400.

[0009] In one embodiment of the present invention, when an epoxy resin is characterized by gel permeation chromatography, the total area B of the peaks representing the region where n is 5 or greater is in the range of 30% to 59% of the total peak area.

[0010] In one embodiment of the present invention, when an epoxy resin is characterized by gel permeation chromatography, the total area A of peaks representing the region where n is less than 5 is in the range of 41% to 70% of the total peak area.

[0011] In one embodiment of the present invention, gel permeation chromatography is performed by dissolving an epoxy resin in tetrahydrofuran at a concentration of 1.25 wt%; supplying the dissolved epoxy resin to a series of separation columns at a flow rate of 1.0 mL / min; and collecting the sample and analyzing the collected sample using a differential refractive index detector, wherein the series of columns consists of one column C1, two columns C2, and one column C3 in a given arrangement, column C1 being 30 cm long, with an inner diameter of 7.8 mm, packed with polystyrene-divinylbenzene having an average particle size of 5 μm and an average pore size of 7.5 nm, column C2 being 30 cm long, with an inner diameter of 7.8 mm, packed with polystyrene-divinylbenzene having an average particle size of 5 μm and an average pore size of 2 nm, and column C3 being 30 cm long, with an inner diameter of 7.8 mm, packed with polystyrene-divinylbenzene having an average particle size of 5 μm and an average pore size of 1.5 nm.

[0012] In one embodiment of the present invention, a methyl ethyl ketone solution of epoxy resin with a solid content of 70% by weight has a viscosity of 200 cp to 800 cp at 25°C.

[0013] In one embodiment of the present invention, the epoxy resin has an epoxy equivalent number of 275 to 300 g / eq.

[0014] In one embodiment of the present invention, the epoxy resin has a softening point of 60°C to 95°C.

[0015] Another object of the present invention is to provide a thermosetting resin composition comprising the epoxy resin and solvent described above.

[0016] In one embodiment of the present invention, the thermosetting resin composition further comprises additives selected from the group consisting of curing agents, curing accelerators, elastomers, fillers, dispersants, reinforcing agents, viscosity modifiers, flame retardants, plasticizers, coupling agents, and combinations thereof.

[0017] Another object of the present invention is to provide a prepreg prepared by impregnating a substrate with the above-mentioned thermosetting resin composition, or by coating a substrate with the above-mentioned thermosetting resin composition and drying the impregnated or coated substrate.

[0018] Another object of the present invention is to provide a metal-clad laminate prepared by laminating the above-mentioned prepreg and metal foil, or by coating the above-mentioned thermosetting resin composition onto the metal foil and drying the coated metal foil.

[0019] To make the above-mentioned objectives, technical features, and advantages of the present invention more apparent, the present invention will be described in detail with reference to several specific embodiments below. [Modes for carrying out the invention]

[0020] Several specific embodiments of the present invention will be described in detail. However, the present invention may be embodied in various embodiments and should not be limited to those described herein.

[0021] Unless otherwise specified, expressions such as "a", "the", etc. as listed in this specification and the claims shall include both the singular and the plural forms.

[0022] In this specification and the claims, the units of weight-average molecular weight (Mw) and number-average molecular weight (Mn) are grams per mole (g / mol).

[0023] When compared with the prior art, the advantages of the present application lie in the improvement of the storage stability and processability of epoxy resins, particularly by controlling the gel permeation chromatography characteristics of epoxy resins. This was surprising because it was not recognized in the prior art that the storage stability and processability of epoxy resins are related to their GPC characteristics. Details of the epoxy resins of the present invention and their uses are provided below.

[0024] 1. Epoxy Resin 1.1. Structure of Epoxy Resin The epoxy resin of the present invention refers to a biphenyl-type epoxy resin, which is defined as a resin containing both biphenyl and epoxy in its molecular structure. The biphenyl-type epoxy resin can be prepared by reacting a biphenyl compound with a phenolic compound to form a biphenyl phenolic resin and then epoxidizing it. In the present invention, the epoxy resin has a structure represented by the following formula (I), [Chemical Formula] In the formula, the definitions of Ar, R, m1, m2 and n are as follows.

[0025] [Ar] Ar is an arylene having one or more epoxy groups. Each Ar may be the same or different, and the H bonded to Ar refers to a hydrogen on the aromatic ring of Ar. Ar is derived from a phenol compound and may be a divalent group that can be further epoxidized. In one embodiment of the present invention, each Ar is independently a divalent group derived from a phenol, cresol, resorcinol, or bisphenol compound and can be further epoxidized. Epoxidation can be carried out by reaction with epichlorohydrin. Thus, each Ar is independently, [ka] This is possible, where R1 and R2 are independently hydrogen atoms or organic groups.

[0026] [R] R is methylene (i.e., -CH2-), which may be a reaction residue obtained by reacting a biphenyl compound with a phenol compound.

[0027] [m1 and m2] m1 and m2 represent the number of methyl groups on the benzene ring of the biphenyl structure. Since the biphenyl structure of the resin may originate from a biphenyl compound, m1 and m2 can independently be integers in the range of 0 to 4, depending on the type of biphenyl compound.

[0028] [n] n is greater than zero and represents the number of repetitions of the structural unit in parentheses. n is preferably in the range of 1 to 400, more specifically 1 to 200, and even more specifically 1 to 100. The value of n can be determined by the molecular weight of the epoxy resin. In one embodiment of the present invention, n is in the range of 1 to 20, which is determined by the weight-average molecular weight Mw of the epoxy resin.

[0029] 1.2. Gel Permeation Chromatography (GPC) Properties of Epoxy Resins When epoxy resins are characterized by gel permeation chromatography, regions with different n values ​​produce distinct signals at different positions on the spectrum. Generally, the smaller the value of n, the longer the elution time in gel permeation chromatography measurements. Therefore, based on the order of elution times, peaks in the gel permeation chromatography spectrum can be sequentially identified by the corresponding n values. The inventors have found that by controlling the peak area ratio of regions representing different n values, the resulting epoxy resin represented by equation (I) exhibits outstanding storage stability and processability.

[0030] Specifically, when epoxy resins are characterized by gel permeation chromatography, the peak representing the region where n is less than 5 has a total area A, the peak representing the region where n is 5 or greater has a total area B, and the ratio of B to A (B / A) is between 0.40 and 1.40. For example, the B / A value may be within the range of 0.40, 0.43, 0.45, 0.48, 0.50, 0.53, 0.55, 0.58, 0.60, 0.63, 0.65, 0.68, 0.70, 0.73, 0.75, 0.78, 0.80, 0.83, 0.85, 0.88, 0.90, 0.93, 0.95, 0.98, 1.00, 1.03, 1.05, 1.08, 1.10, 1.13, 1.15, 1.18, 1.20, 1.23, 1.25, 1.28, 1.30, 1.33, 1.35, 1.38, or 1.40, or any two of the values ​​described herein. The inventors have found that when the B / A value falls below the lower limit of the above range, the storage stability of the epoxy resin represented by formula (I) is insufficient, and the epoxy resin tends to precipitate from the solvent. When the B / A value exceeds the upper limit of the above range, the processability of the epoxy resin represented by formula (I) is insufficient, and the resulting metal-clad laminate has resin defects, resulting in an incomplete dielectric layer.

[0031] In this invention, gel permeation chromatography is performed by dissolving an epoxy resin in tetrahydrofuran at a concentration of 1.25 wt%; supplying the dissolved epoxy resin to a series of separation columns at a flow rate of 1.0 mL / min; and collecting the sample and analyzing the collected sample using a differential refractive index detector, wherein the series of columns consists of one column C1, two columns C2, and one column C3 in a given arrangement, column C1 is 30 cm long, has an inner diameter of 7.8 mm, and is packed with polystyrene-divinylbenzene with an average particle size of 5 μm and an average pore size of 7.5 nm, column C2 is 30 cm long, has an inner diameter of 7.8 mm, and is packed with polystyrene-divinylbenzene with an average particle size of 5 μm and an average pore size of 2 nm, and column C3 is 30 cm long, has an inner diameter of 7.8 mm, and is packed with polystyrene-divinylbenzene with an average particle size of 5 μm and an average pore size of 1.5 nm. In this invention, the peaks in the obtained gel permeation chromatography spectrum can be sequentially identified by corresponding n values ​​based on the order of elution times. Software is then used to assist in calculating the peak area and the corresponding ratio for the region representing each n value, and the peak area is calculated as the integral area defined by connecting the start and end points of peaks within a specific range with lines.

[0032] Under conditions where the B / A value is between 0.40 and 1.40, the signal distribution in the gel permeation chromatography spectrum is not particularly limited to the region where n is less than 5 and the region where n is 5 or greater. That is, the region where n is less than 5 may consist of one or more subregions where n is less than 5. The region where n is 5 or greater may consist of one or more subregions where n is 5 or greater, and more specifically, these may consist of one or more subregions where n is in the range of 5 to 400. In one embodiment of the present invention, the region where n is less than 5 mainly includes the subregions where n=1, n=2, n=3, and n=4, and the region where n is 5 or greater mainly includes the subregions where n=5, n=6, and n=7.

[0033] In one embodiment of the present invention, when an epoxy resin is characterized by gel permeation chromatography, the total area B of peaks representing the region where n is 5 or greater is in the range of 30% to 59% of the total peak area. For example, the total area B of peaks representing the region where n is 5 or greater relative to the total peak area may be within the range of 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, or 59%, or any two of the values ​​described herein.

[0034] In one embodiment of the present invention, when an epoxy resin is characterized by gel permeation chromatography, the total area A of peaks representing the region where n is less than 5 is in the range of 41% to 70% of the total peak area. For example, the total area A of peaks representing the region where n is less than 5 relative to the total peak area may be within the range of 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, or 70%, or any two of the values ​​described herein.

[0035] In one embodiment of the present invention, when an epoxy resin is characterized by gel permeation chromatography, the peak representing the region where n is 1 has an area a1, and area a1 is 20% or more of the total peak area, more specifically in the range of 20% to 30% of the total peak area. For example, with respect to the total peak area, area a1 may be within the range of 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%, or any two of the values ​​described herein.

[0036] The GPC properties of the epoxy resin of the present invention can be adjusted by controlling the composition of the raw materials or the reaction conditions. For example, a method for controlling the composition of the raw materials includes controlling the molar ratio of the phenol compound to the biphenyl compound in the raw materials to adjust the B / A value. Generally, the higher the molar ratio of the phenol compound to the biphenyl compound (moles of phenol compound / moles of biphenyl compound), the lower the B / A value, and conversely, the lower the molar ratio, the higher the B / A value. A method for controlling the reaction conditions includes controlling the reaction temperature or preparing the resin using a stepwise polymerization process. Generally, the higher the reaction temperature, the higher the B / A value, and conversely, the lower the reaction temperature, the lower the B / A value.

[0037] 1.3. Other properties of epoxy resins Under conditions where the B / A value is between 0.40 and 1.40, other properties of the epoxy resin of the present invention can be adaptively adjusted according to the requirements of the intended application.

[0038] In one embodiment of the present invention, the epoxy resin has a weight-average molecular weight of 1600 or more, preferably 1600 to 5000. For example, the weight-average molecular weight Mw of the epoxy resin may be within the range of 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300, 2400, 2500, 2600, 2700, 2800, 2900, 3000, 3100, 3200, 3300, 3400, 3500, 3600, 3700, 3800, 3900, 4000, 4100, 4200, 4300, 4400, 4500, 4600, 4700, 4800, 4900, or 5000, or any two of the values ​​described herein. The unit of weight-average molecular weight Mw is g / mol. The weight-average molecular weight (Mw) is measured by the gel permeation chromatography described above.

[0039] The epoxy resin may have a number-average molecular weight Mn in the range of 800 to 2000, preferably 850 to 1600. For example, the number-average molecular weight Mn of the epoxy resin may be within the range of 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, or 1600, or any two of the values ​​described herein.

[0040] Epoxy resins may have a polydispersity index PDI (i.e., "Mw / Mn") in the range of 1.1 to 4.5, preferably 1.4 to 4.3. For example, the polydispersity index PDI of an epoxy resin may be within the range of 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.4 or 4.5, or any two of the values ​​described herein.

[0041] In one embodiment of the present invention, a methyl ethyl ketone solution of an epoxy resin with a solid content of 70% by weight has a viscosity of 200 cp to 800 cp at 25°C. For example, the viscosity of a methyl ethyl ketone solution of an epoxy resin with a solid content of 70% by weight at 25°C may be within the range of 200 cp, 250 cp, 300 cp, 350 cp, 400 cp, 450 cp, 500 cp, 550 cp, 600 cp, 650 cp, 700 cp, 750 cp, or 800 cp, or any two of the values ​​described herein.

[0042] In one embodiment of the present invention, the epoxy resin has an epoxy equivalent number of 275 to 300 g / eq. For example, the epoxy equivalent number of the epoxy resin may be within the range of 275 g / eq, 276 g / eq, 277 g / eq, 278 g / eq, 279 g / eq, 280 g / eq, 281 g / eq, 282 g / eq, 283 g / eq, 284 g / eq, 285 g / eq, 286 g / eq, 287 g / eq, 288 g / eq, 289 g / eq, 290 g / eq, 291 g / eq, 292 g / eq, 293 g / eq, 294 g / eq, 295 g / eq, 296 g / eq, 297 g / eq, 298 g / eq, 299 g / eq, or 300 g / eq, or any two of the values ​​described herein. The epoxy equivalent number is measured according to ASTM D1652.

[0043] In one embodiment of the present invention, the epoxy resin has a softening point of 60°C to 95°C. For example, the softening point of the epoxy resin may be within the range of 60°C, 62.5°C, 65°C, 67.5°C, 70°C, 72.5°C, 75°C, 77.5°C, 80°C, 82.5°C, 85°C, 87.5°C, 90°C, 92.5°C, or 95°C, or any two of the values ​​described herein.

[0044] 2. Preparation of epoxy resin The method for preparing the epoxy resin of the present invention is not particularly limited. For example, the epoxy resin can be prepared by reacting a biphenyl compound and a phenol compound at an appropriate temperature to obtain a phenol resin, and then carrying out an epoxidation reaction with this phenol resin and epichlorohydrin. Detailed preparation methods are illustrated in the following examples and will be described in more detail here.

[0045] 3.Resin composition The epoxy resin of the present invention has excellent storage stability and can be uniformly mixed with solvents and, optionally, additives, and dissolved or dispersed in the solvent to form slurries, colloids, varnishes, and other forms. Accordingly, the present invention also provides a thermosetting resin composition comprising the epoxy resin and solvent described above.

[0046] The solvent can be any inert solvent that can dissolve or disperse the components of the resin composition but does not react with these components, including aromatic hydrocarbons, ethers, alcohols, or ketones. Examples of solvents include, but are not limited to, acetone, buttanone, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, propylene glycol methyl ether, γ-butyrol actone, dimethylformamide (DMF), dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP). The solvents described above can be used individually or in any combination. The amount of solvent used is not particularly limited, as long as the components of the resin composition can be uniformly dissolved or dispersed.

[0047] Without departing from the technical principles of the present invention, the resin composition of the present invention may further contain any components depending on the need to adaptively improve the processability of the resin composition during the manufacturing process, or the need to improve the physicochemical properties of the electronic material produced from the resin composition. Examples of optional components include, but are not limited to, additives selected from the group consisting of curing agents, curing accelerators, elastomers, fillers, dispersants, reinforcing agents, viscosity modifiers, flame retardants, plasticizers, and coupling agents. The above-mentioned additives may be used individually or in any combination.

[0048] 4. Prepreg and metal-clad laminates The present invention also provides a prepreg prepared from the thermosetting resin composition described above. The prepreg is prepared by impregnating a substrate with the thermosetting resin composition described above, or by coating a substrate with the thermosetting resin composition described above and drying the impregnated or coated substrate. The substrate may be a reinforcing material. Generally, examples of reinforcing materials include, but are not limited to, fibers selected from the group consisting of glass fibers, inorganic fibers other than glass fibers, organic fibers, and combinations thereof. Examples of glass fibers include, but are not limited to, E glass fibers, NE glass fibers, S glass fibers, L glass fibers, D glass fibers, T glass fibers, Q glass fibers, UN glass fibers, and spherical glass. Examples of inorganic fibers other than glass fibers include, but are not limited to, quartz fibers, paper fibers, and carbon fibers. Examples of organic fibers include, but are not limited to, polyimides, polyamides (such as Kevlar), polyesters, liquid crystal polymers (such as liquid crystal polyesters), polytetrafluoroethylenes, ultra-high molecular weight polyethylene (UHMWPE), and high-modulus polypropylene (HMPP). Examples of reinforcing materials include, but are not limited to, woven fabrics, nonwoven fabrics, roving yarns, chopped strand felts, and surface felts.

[0049] In addition, the present invention also provides a metal-clad laminate prepared from the above-described prepregs. The metal-clad laminate comprises a dielectric layer and a metal layer on at least one surface of the dielectric layer, wherein the dielectric layer is formed from a prepreg and the metal layer is formed from a metal foil. Specifically, a metal-clad laminate can be obtained by stacking a plurality of the above-described prepregs, stacking a metal foil (such as copper foil) on at least one outer surface of the dielectric layer formed from the prepregs, providing a stacked object, and then hot-pressing the stacked object to obtain a metal-clad laminate. Alternatively, a metal-clad laminate can be prepared by directly coating the above-described thermosetting resin composition onto a metal foil and drying the coated metal foil.

[0050] The outer metal foil of the metal-clad laminate can be further patterned to form a printed circuit board.

[0051] 5. Examples 5.1. Test Method [Gel Permeation Chromatography (GPC) Test] The prepared epoxy resin was dissolved in tetrahydrofuran at a concentration of 1.25 wt% and then supplied at a flow rate of 1.0 mL / min to a series of separation columns consisting of one column C1 (model: TOSOH TSKgel G3000HxL), two columns C2 (model: TOSOH TSKgel G2000HxL), and one column C3 (model: TOSOH TSKgel G1000HxL). Column C1 is 30 cm long and 7.8 mm inner diameter, packed with polystyrene-divinylbenzene with an average particle size of 5 μm and an average pore size of 7.5 nm. Column C2 is 30 cm long and 7.8 mm inner diameter, packed with polystyrene-divinylbenzene with an average particle size of 5 μm and an average pore size of 2 nm. Column C3 is 30 cm long and 7.8 mm in diameter, packed with polystyrene-divinylbenzene with an average particle size of 5 μm and an average pore size of 1.5 nm. The sample is collected and analyzed using a differential refractive index detector (model: Waters 2414 RI detector). The peaks in the resulting gel permeation chromatography spectrum can be sequentially identified by the corresponding n values ​​based on the order of elution times. Then, using SISC32 software available from Scientific Information Service Company, the peak area and the corresponding ratio for the region representing each n value are calculated, and the peak area is calculated as the integral area defined by connecting the start and end points of peaks within a specific range with lines.

[0052] [Viscosity measurement] The prepared epoxy resin is mixed with a methyl ethyl ketone solution containing 70% by weight of solids and left to stand in a constant temperature bath at 25°C for 2 hours. The viscosity is then measured using a Brookfield viscometer. The unit of viscosity is centipoise (cp).

[0053] [Epoxy equivalent number measurement] The epoxy equivalent number of the prepared epoxy resin is measured according to ASTM D1652. The unit of epoxy equivalent number is g / eq.

[0054] [Softening point measurement] The softening point of the prepared epoxy resin is measured according to JIS K 7234. The unit of the softening point is °C.

[0055] [Storage stability test] The prepared epoxy resin is mixed with a methyl ethyl ketone solution containing 70% by weight of solids and left to stand in a refrigerator at 5°C. The solution is observed daily for any precipitation. The time at which precipitation occurs is recorded. If no precipitation is observed after 70 days, "No precipitation" is recorded.

[0056] [Processability test] The prepared epoxy resin is mixed with phenolic resin (PF8110, available from Chang Chun Plastics Company) in a 1:1 ratio (epoxy equivalents to hydroxy equivalents) to prepare a varnish, and the gel time is controlled to 100s-120s. Glass fiber fabric is impregnated with the varnish and then dried to prepare a prepreg. Five layers of prepreg are stacked, copper foil is placed on the top layer on each side, and then hot pressing is performed. After hot pressing, the copper foil is removed by etching, and the surface of the glass fiber fabric is checked for resin defects. If resin defects are observed, this indicates a failure of the processability test, and the result is recorded as "x". If no resin defects are observed, this indicates a pass of the processability test, and the result is recorded as "○".

[0057] 5.2. Preparation of epoxy resin [Example 1] 275.3 g of phenol and 1 g of p-toluenesulfonic acid were placed in a four-necked flask equipped with a stirrer, thermometer, and condenser. While stirring at 80°C, 306.1 g of 4,4'-bis(chloromethyl)-1,1'-biphenyl was added, and the reaction was maintained at 80°C for 2 hours to obtain the reaction product. Methyl isobutyl ketone was added to the reaction product to adjust the resin solids content to 50% by weight, and then washed with water. After washing with water, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, thereby obtaining the phenolic resin.

[0058] 100 g of prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were homogeneously mixed. The temperature was then raised to 55°C, and 40 g of potassium hydroxide was added to the batch over 120 minutes. The reaction was carried out at 55°C for 2 hours, then the temperature was raised to 70°C, and the reaction was continued at 70°C for 1 hour. Upon completion of the reaction, pure water was added, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The filtered product was then dissolved in 560 g of methyl isobutyl ketone. The temperature was raised to 55°C, and 2 g of 30 wt% aqueous sodium hydroxide solution was added, followed by a reaction for 1 hour. After completion of the reaction, pure water was added again, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, thereby obtaining epoxy resin. The prepared epoxy resin has a weight-average molecular weight (Mw) of 1654, a number-average molecular weight (Mn) of 895, and a polydispersity index (PDI) of 1.848.

[0059] [Example 2] 29.8 g of phenol and 1 g of p-toluenesulfonic acid were placed in a four-necked flask equipped with a stirrer, thermometer, and condenser. While stirring at 90°C, 42.2 g of 4,4'-bis(chloromethyl)-1,1'-biphenyl was added, and the reaction was maintained at 90°C for 2 hours. Subsequently, 94.1 g of phenol and 84.5 g of 4,4'-bis(chloromethyl)-1,1'-biphenyl were added, and the reaction was maintained at 90°C for 2 hours to obtain the reaction product. Methyl isobutyl ketone was added to the reaction product to adjust the resin solids content to 50% by weight, and then washed with water. After washing with water, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, thereby obtaining the phenolic resin.

[0060] 100 g of prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were homogeneously mixed. The temperature was then raised to 55°C, and 40 g of potassium hydroxide was added to the batch over 120 minutes. The reaction was carried out at 55°C for 2 hours, then the temperature was raised to 70°C, and the reaction was continued at 70°C for 1 hour. Upon completion of the reaction, pure water was added, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The filtered product was then dissolved in 560 g of methyl isobutyl ketone. The temperature was raised to 55°C, and 2 g of 30 wt% aqueous sodium hydroxide solution was added, followed by a reaction for 1 hour. After completion of the reaction, pure water was added again, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, thereby obtaining epoxy resin. The prepared epoxy resin has a weight-average molecular weight (Mw) of 3587, a number-average molecular weight (Mn) of 998, and a polydispersity index (PDI) of 3.594.

[0061] [Example 3] 275.3 g of phenol and 1 g of p-toluenesulfonic acid were placed in a four-necked flask equipped with a stirrer, thermometer, and condenser. While stirring at 80°C, 329.5 g of 4,4'-bis(chloromethyl)-1,1'-biphenyl was added, and the reaction was maintained at 80°C for 2 hours to obtain the reaction product. Methyl isobutyl ketone was added to the reaction product to adjust the resin solids content to 50% by weight, and then washed with water. After washing with water, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, thereby obtaining the phenolic resin.

[0062] 100 g of prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were homogeneously mixed. The temperature was then raised to 55°C, and 40 g of potassium hydroxide was added to the batch over 120 minutes. The reaction was carried out at 55°C for 2 hours, then the temperature was raised to 70°C, and the reaction was continued at 70°C for 1 hour. Upon completion of the reaction, pure water was added, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The filtered product was then dissolved in 560 g of methyl isobutyl ketone. The temperature was raised to 55°C, and 2 g of 30 wt% aqueous sodium hydroxide solution was added, followed by a reaction for 1 hour. After completion of the reaction, pure water was added again, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, thereby obtaining epoxy resin. The prepared epoxy resin has a weight-average molecular weight Mw of 1771, a number-average molecular weight Mn of 917, and a polydispersity index PDI of 1.931.

[0063] [Example 4] 89.2 g of phenol and 1 g of p-toluenesulfonic acid were placed in a four-necked flask equipped with a stirrer, thermometer, and condenser. While stirring at 100°C, 140.0 g of 4,4'-bis(chloromethyl)-1,1'-biphenyl was added, and the reaction was maintained at 100°C for 2 hours. Subsequently, 336.0 g of phenol and 280.0 g of 4,4'-bis(chloromethyl)-1,1'-biphenyl were added, and the reaction was maintained at 100°C for 2 hours to obtain the reaction product. Methyl isobutyl ketone was added to the reaction product to adjust the resin solids content to 50% by weight, and then washed with water. After washing with water, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, thereby obtaining the phenolic resin.

[0064] 100 g of prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were homogeneously mixed. The temperature was then raised to 55°C, and 40 g of potassium hydroxide was added to the batch over 120 minutes. The reaction was carried out at 55°C for 2 hours, then the temperature was raised to 70°C, and the reaction was continued at 70°C for 1 hour. Upon completion of the reaction, pure water was added, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The filtered product was then dissolved in 560 g of methyl isobutyl ketone. The temperature was raised to 55°C, and 2 g of 30 wt% aqueous sodium hydroxide solution was added, followed by a reaction for 1 hour. After completion of the reaction, pure water was added again, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, thereby obtaining epoxy resin. The prepared epoxy resin has a weight-average molecular weight Mw of 2911, a number-average molecular weight Mn of 982, and a polydispersity index PDI of 2.964.

[0065] [Example 5] 70.1 g of phenol and 1 g of p-toluenesulfonic acid were placed in a four-necked flask equipped with a stirrer, thermometer, and condenser. While stirring at 100°C, 110.0 g of 4,4'-bis(chloromethyl)-1,1'-biphenyl was added, and the reaction was maintained at 100°C for 2 hours. Subsequently, 247.3 g of phenol and 220.0 g of 4,4'-bis(chloromethyl)-1,1'-biphenyl were added, and the reaction was maintained at 100°C for 2 hours to obtain the reaction product. Methyl isobutyl ketone was added to the reaction product to adjust the resin solids content to 50% by weight, and then washed with water. After washing with water, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, thereby obtaining the phenolic resin.

[0066] 100 g of prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were homogeneously mixed. The temperature was then raised to 55°C, and 40 g of potassium hydroxide was added to the batch over 120 minutes. The reaction was carried out at 55°C for 2 hours, then the temperature was raised to 70°C, and the reaction was continued at 70°C for 1 hour. Upon completion of the reaction, pure water was added, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The filtered product was then dissolved in 560 g of methyl isobutyl ketone. The temperature was raised to 55°C, and 2 g of 30 wt% aqueous sodium hydroxide solution was added, followed by a reaction for 1 hour. After completion of the reaction, pure water was added again, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, thereby obtaining epoxy resin. The prepared epoxy resin has a weight-average molecular weight Mw of 4275, a number-average molecular weight Mn of 10¹², and a polydispersity index PDI of 4.224.

[0067] [Example 6] 129.2 g of phenol and 1 g of p-toluenesulfonic acid were placed in a four-necked flask equipped with a stirrer, thermometer, and condenser. While stirring at 100°C, 202.8 g of 4,4'-bis(chloromethyl)-1,1'-biphenyl was added, and the reaction was maintained at 100°C for 2 hours to obtain the reaction product. Methyl isobutyl ketone was added to the reaction product to adjust the resin solids content to 50% by weight, and then washed with water. After washing with water, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, thereby obtaining the phenolic resin.

[0068] 100 g of prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were homogeneously mixed. The temperature was then raised to 55°C, and 40 g of potassium hydroxide was added to the batch over 120 minutes. The reaction was carried out at 55°C for 2 hours, then the temperature was raised to 70°C, and the reaction was continued at 70°C for 1 hour. Upon completion of the reaction, pure water was added, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The filtered product was then dissolved in 560 g of methyl isobutyl ketone. The temperature was raised to 55°C, and 2 g of 30 wt% aqueous sodium hydroxide solution was added, followed by a reaction for 1 hour. After completion of the reaction, pure water was added again, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, thereby obtaining epoxy resin. The prepared epoxy resin has a weight-average molecular weight (Mw) of 4778, a number-average molecular weight (Mn) of 1474, and a polydispersity index (PDI) of 3.242.

[0069] [Comparative Example 1] 526.1 g of phenol and 1 g of p-toluenesulfonic acid were placed in a four-necked flask equipped with a stirrer, thermometer, and condenser. While stirring at 70°C, 329.5 g of 4,4'-bis(chloromethyl)-1,1'-biphenyl was added, and the reaction was maintained at 70°C for 2 hours to obtain the reaction product. Methyl isobutyl ketone was added to the reaction product to adjust the resin solids content to 50% by weight, and then washed with water. After washing with water, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, thereby obtaining the phenol resin.

[0070] 100 g of prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were homogeneously mixed. The temperature was then raised to 55°C, and 40 g of potassium hydroxide was added to the batch over 120 minutes. The reaction was carried out at 55°C for 2 hours, then the temperature was raised to 70°C, and the reaction was continued at 70°C for 1 hour. Upon completion of the reaction, pure water was added, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The filtered product was then dissolved in 560 g of methyl isobutyl ketone. The temperature was raised to 55°C, and 2 g of 30 wt% aqueous sodium hydroxide solution was added, followed by a reaction for 1 hour. After completion of the reaction, pure water was added again, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, thereby obtaining epoxy resin. The prepared epoxy resin has a weight-average molecular weight Mw of 909, a number-average molecular weight Mn of 622, and a polydispersity index PDI of 1.461.

[0071] [Comparative Example 2] 182.7 g of phenol and 1 g of p-toluenesulfonic acid were placed in a four-necked flask equipped with a stirrer, thermometer, and condenser. While stirring at 70°C, 130.0 g of 4,4'-bis(chloromethyl)-1,1'-biphenyl was added, and the reaction was maintained at 70°C for 2 hours to obtain the reaction product. Methyl isobutyl ketone was added to the reaction product to adjust the resin solids content to 50% by weight, and then washed with water. After washing with water, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, thereby obtaining the phenolic resin.

[0072] 100 g of prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were homogeneously mixed. The temperature was then raised to 55°C, and 40 g of potassium hydroxide was added to the batch over 120 minutes. The reaction was carried out at 55°C for 2 hours, then the temperature was raised to 70°C, and the reaction was continued at 70°C for 1 hour. Upon completion of the reaction, pure water was added, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The filtered product was then dissolved in 560 g of methyl isobutyl ketone. The temperature was raised to 55°C, and 2 g of 30 wt% aqueous sodium hydroxide solution was added, followed by a reaction for 1 hour. After completion of the reaction, pure water was added again, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, thereby obtaining epoxy resin. The prepared epoxy resin has a weight-average molecular weight Mw of 1127, a number-average molecular weight Mn of 718, and a polydispersity index PDI of 1.570.

[0073] [Comparative Example 3] 129.2 g of phenol and 1 g of p-toluenesulfonic acid were placed in a four-necked flask equipped with a stirrer, thermometer, and condenser. While stirring at 100°C, 215.4 g of 4,4'-bis(chloromethyl)-1,1'-biphenyl was added, and the reaction was maintained at 100°C for 2 hours to obtain the reaction product. Methyl isobutyl ketone was added to the reaction product to adjust the resin solids content to 50% by weight, and then washed with water. After washing with water, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, thereby obtaining the phenolic resin.

[0074] 100 g of prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were homogeneously mixed. The temperature was then raised to 55°C, and 40 g of potassium hydroxide was added to the batch over 120 minutes. The reaction was carried out at 55°C for 2 hours, then the temperature was raised to 70°C, and the reaction was continued at 70°C for 1 hour. Upon completion of the reaction, pure water was added, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The filtered product was then dissolved in 560 g of methyl isobutyl ketone. The temperature was raised to 55°C, and 2 g of 30 wt% aqueous sodium hydroxide solution was added, followed by a reaction for 1 hour. After completion of the reaction, pure water was added again, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, thereby obtaining epoxy resin. The prepared epoxy resin has a weight-average molecular weight Mw of 6258, a number-average molecular weight Mn of 1808, and a polydispersity index PDI of 3.461.

[0075] [Comparative Example 4] 129.2 g of phenol and 1 g of p-toluenesulfonic acid were placed in a four-necked flask equipped with a stirrer, thermometer, and condenser. While stirring at 110°C, 202.8 g of 4,4'-bis(chloromethyl)-1,1'-biphenyl was added, and the reaction was maintained at 110°C for 2 hours to obtain the reaction product. Methyl isobutyl ketone was added to the reaction product to adjust the resin solids content to 50% by weight, and then washed with water. After washing with water, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, thereby obtaining the phenolic resin.

[0076] 100 g of prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were homogeneously mixed. The temperature was then raised to 55°C, and 40 g of potassium hydroxide was added to the batch over 120 minutes. The reaction was carried out at 55°C for 2 hours, then the temperature was raised to 70°C, and the reaction was continued at 70°C for 1 hour. Upon completion of the reaction, pure water was added, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The filtered product was then dissolved in 560 g of methyl isobutyl ketone. The temperature was raised to 55°C, and 2 g of 30 wt% aqueous sodium hydroxide solution was added, followed by a reaction for 1 hour. After completion of the reaction, pure water was added again, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, thereby obtaining epoxy resin. The prepared epoxy resin has a weight-average molecular weight Mw of 4902, a number-average molecular weight Mn of 1502, and a polydispersity index PDI of 3.264.

[0077] [Comparative Example 5] 129.2 g of phenol and 1 g of p-toluenesulfonic acid were placed in a four-necked flask equipped with a stirrer, thermometer, and condenser. While stirring at 70°C, 208.9 g of 4,4'-bis(chloromethyl)-1,1'-biphenyl was added, and the reaction was maintained at 70°C for 2 hours to obtain the reaction product. Methyl isobutyl ketone was added to the reaction product to adjust the resin solids content to 50% by weight, and then washed with water. After washing with water, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, thereby obtaining the phenolic resin.

[0078] 100 g of prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were homogeneously mixed. The temperature was then raised to 55°C, and 40 g of potassium hydroxide was added to the batch over 120 minutes. The reaction was carried out at 55°C for 2 hours, then the temperature was raised to 70°C, and the reaction was continued at 70°C for 1 hour. Upon completion of the reaction, pure water was added, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The filtered product was then dissolved in 560 g of methyl isobutyl ketone. The temperature was raised to 55°C, and 2 g of 30 wt% aqueous sodium hydroxide solution was added, followed by a reaction for 1 hour. After completion of the reaction, pure water was added again, and the washing process was repeated until the product became neutral. After washing with water, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, thereby obtaining epoxy resin. The prepared epoxy resin has a weight-average molecular weight Mw of 4655, a number-average molecular weight Mn of 1540, and a polydispersity index PDI of 3.023.

[0079] 5.3. Characterization of epoxy resins The properties of the epoxy resins of Examples 1-6 and Comparative Examples 1-5, including gel permeation chromatography properties, viscosity, epoxy equivalent number, softening point, storage stability, and processability, were measured according to the test methods described above, and the results were recorded in Tables 1-1 and 1-2.

[0080] [Table 1-1]

[0081] [Table 1-2]

[0082] As shown in Tables 1-1 and 1-2, the epoxy resins of Examples 1-6 of the present invention had a precipitation time of 18 days or more, which indicated good storage stability, and no resin defects were observed, indicating good processability. In contrast, the epoxy resins of Comparative Examples 1-5 did not simultaneously exhibit these outstanding properties. Comparative Examples 1 and 2, when the B / A value was lower than the range specified in the present invention, precipitated from the solvent in a very short time, but showed insufficient storage stability. Comparative Examples 3-5, when the B / A value was higher than the range specified in the present invention, experienced resin defects, failed to form the desired shape, and showed insufficient processability.

[0083] The above embodiments demonstrate the principle and effectiveness of the present application and its inventive features. Those skilled in the art can proceed with various modifications and substitutions based on the disclosed and proposed features described herein, without departing from the principle. Accordingly, the scope of protection of the present application is as defined in the appended claims.

Claims

1. An epoxy resin represented by the following formula (I), 【Chemistry 1】 During the ceremony, Each Ar is an arylene having one or more epoxy groups, and each Ar may be the same or different. Each R is a methylene group. m1 and m2 are independent integers in the range of 0 to 4. n is greater than zero, The epoxy resin, when characterized by gel permeation chromatography (GPC), has a peak representing the region where n is less than 5 with a total area A, a peak representing the region where n is 5 or more with a total area B, and the ratio of B to A (B / A) is 0.40 to 1.

40.

2. The epoxy resin according to claim 1, wherein each Ar is independently a divalent group derived from phenol, cresol, m-benzenediol, or a bisphenol compound, and is further epoxidized.

3. The epoxy resin according to claim 1, wherein n is in the range of 1 to 400.

4. The epoxy resin according to claim 1, wherein, when the epoxy resin is characterized by gel permeation chromatography, the total area B of the peaks representing the region where n is 5 or more is in the range of 30% to 59% of the total peak area.

5. The epoxy resin according to claim 1, wherein, when the epoxy resin is characterized by gel permeation chromatography, the total area A of the peaks representing the region where n is less than 5 is in the range of 41% to 70% of the total peak area.

6. The epoxy resin according to any one of claims 1 to 5, wherein the gel permeation chromatography is performed by dissolving the epoxy resin in tetrahydrofuran at a concentration of 1.25% by weight; supplying the dissolved epoxy resin to a series of separation columns at a flow rate of 1.0 mL / min; and collecting the sample and analyzing the collected sample using a differential refractive index detector, wherein the series of columns consists of one column C1, two columns C2 and one column C3 in a given arrangement, the epoxy resin according to any one of claims 1 to 5, wherein column C1 is packed with polystyrene-divinylbenzene having a length of 30 cm, an inner diameter of 7.8 mm, an average particle size of 5 μm, and an average pore size of 7.5 nm, the columns C2 are each packed with polystyrene-divinylbenzene having a length of 30 cm, an inner diameter of 7.8 mm, an average particle size of 5 μm, and an average pore size of 2 nm, and the column C3 is packed with polystyrene-divinylbenzene having a length of 30 cm, an inner diameter of 7.8 mm, an average particle size of 5 μm, and an average pore size of 1.5 nm.

7. The epoxy resin according to any one of claims 1 to 5, wherein a methyl ethyl ketone solution of the epoxy resin having a solid content of 70% by weight has a viscosity of 200 cp to 800 cp at 25°C.

8. The epoxy resin according to any one of claims 1 to 5, wherein the epoxy resin has an epoxy equivalent number of 275 to 300 g / eq.

9. The epoxy resin according to any one of claims 1 to 5, wherein the epoxy resin has a softening point of 60°C to 95°C.

10. A thermosetting resin composition comprising the epoxy resin and solvent according to any one of claims 1 to 5.

11. The thermosetting resin composition according to claim 10, further comprising an additive selected from the group consisting of a curing agent, a curing accelerator, an elastomer, a filler, a dispersant, a reinforcing agent, a viscosity modifier, a flame retardant, a plasticizer, a coupling agent, and combinations thereof.

12. A prepreg prepared by impregnating a substrate with the thermosetting resin composition described in claim 10, or by coating a substrate with the thermosetting resin composition described in claim 10 and drying the impregnated or coated substrate.

13. A metal-clad laminate prepared by laminating the prepreg described in claim 12 with a metal foil.

14. A metal-clad laminate prepared by coating a metal foil with the thermosetting resin composition described in claim 10, and drying the coated metal foil.

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