Epoxy resin and application thereof

Abstract

The present invention provides an epoxy resin represented by the following formula (I): wherein Ar is a stretching aryl group having an epoxy group, and each Ar may be the same or different; r is a methyl group; m1 and m2 are each independently an integer from 0 to 4; n is greater than 0; and when the epoxy resin is measured by gel permeation chromatography (GPC), the sum of the peak areas of the portions where n is less than 5 is A, the sum of the peak areas of the portions where n is 5 or more is B, and the ratio of B to A (B / A) is 0.40 to 1.40.

Description

Technical Field

[0001] This invention relates to an epoxy resin, and more particularly to an epoxy resin exhibiting specific gel permeation chromatography (GPC) properties. The epoxy resin of this invention possesses good solvent solubility, preservation, and processability, making it particularly suitable for use in metal foil laminates. Background Technology

[0002] Printed circuit boards (PCBs) serve as substrates for electronic devices, housing various electrically interconnected electronic components to provide a stable circuit operating environment. A common PCB substrate is the copper clad laminate (CCL).

[0003] Generally, copper foil laminates can be manufactured as follows: A thermosetting resin (e.g., phenolic resin, epoxy resin, etc.) is uniformly mixed with other additives and dissolved or dispersed in a solvent to form a varnish. A reinforcing material (e.g., fiberglass fabric) is impregnated with this varnish, and the impregnated reinforcing material is cured to a semi-cured state (i.e., B-stage) to obtain a precured sheet. Subsequently, a predetermined number of precured sheets are stacked, and a copper foil is stacked on at least one outer side of the stacked precured sheets to provide a laminate. The laminate is then subjected to a hot-pressing operation (i.e., C-stage) to obtain a copper foil laminate.

[0004] Examples of thermosetting resins include phenolic resins and epoxy resins, among which epoxy resins are widely used due to their excellent insulation and heat resistance. However, to ensure the quality stability of copper foil laminates, the varnish formulated with thermosetting resins must have good shelf life, meaning that it should not crystallize or separate during long-term storage. Existing epoxy resins generally suffer from the problem of easy crystallization and poor solvent solubility and shelf life. Summary of the Invention

[0005] In view of this, the present invention aims to provide an epoxy resin that not only has good solvent solubility and preservation properties, but also exhibits good processability in the application of dielectric layer materials for the manufacture of metal foil laminates, and the resulting metal foil laminates will not have adhesive shortage.

[0006] Therefore, one object of the present invention is to provide an epoxy resin as shown in formula (I),

[0007]

[0008] in,

[0009] Ar is an aryl group with an epoxy group, and each Ar may be the same or different;

[0010] R is an elongyl group;

[0011] m1 and m2 are each independent integers from 0 to 4;

[0012] n is greater than 0; and

[0013] When the epoxy resin is measured by gel permeation chromatography, the sum of the peak areas of the portion where n is less than 5 is called A, and the sum of the peak areas of the portion where n is greater than 5 is called B, and the ratio of B to A (B / A) is 0.40 to 1.40.

[0014] In one embodiment of the present invention, each Ar is independently a divalent group derived from phenol, cresol, resorcinol, or bisphenol compounds and further epoxidized.

[0015] In one embodiment of the present invention, n is 1 to 400.

[0016] In one embodiment of the present invention, when the epoxy resin is measured by gel permeation chromatography, the sum of the peak areas B of the portions where n is 5 or more accounts for 30% to 59% of the total area.

[0017] In one embodiment of the present invention, when the epoxy resin is measured by gel permeation chromatography, the sum of the peak areas A of the portions where n is less than 5 accounts for 41% to 70% of the total area.

[0018] In one embodiment of the present invention, gel permeation chromatography is performed under the following test conditions: epoxy resin is dissolved in tetrahydrofuran at a concentration of 1.25% by weight; separation is performed by sequentially connecting a column C1, two columns C2, and a column C3 at a flow rate of 1.0 mL / min, wherein column C1 is 30 cm long, has an inner diameter of 7.8 mm, and is filled with polystyrene-divinylbenzene with an average particle size of 5 μm and an average pore size of 7.5 nm; each of the columns C2 is 30 cm long, has an inner diameter of 7.8 mm, and is filled 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 filled 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 refractive index detector.

[0019] In one embodiment of the present invention, a 70% by weight solids solution of epoxy resin in methyl ethyl ketone has a viscosity of 200 centipoise (cp) to 800 centipoise at 25°C.

[0020] In one embodiment of the present invention, the epoxy equivalent of the epoxy resin is 275 to 300 g / eq.

[0021] In one embodiment of the present invention, the softening point of the epoxy resin is 60°C to 95°C.

[0022] Another object of the present invention is to provide a thermosetting resin composition comprising the above-mentioned epoxy resin and solvent.

[0023] In one embodiment of the invention, the thermosetting resin composition further comprises additives selected from the group consisting of: hardeners, hardening accelerators, elastomers, fillers, dispersants, toughening agents, viscosity modifiers, flame retardants, plasticizers, coupling agents, and combinations thereof.

[0024] Another object of the present invention is to provide a semi-cured sheet, which is obtained by impregnating or coating a substrate with the above-mentioned thermosetting resin composition and drying the impregnated or coated substrate.

[0025] Another object of the present invention is to provide a metal foil laminate, which is obtained by laminating the above-mentioned prepreg with a metal foil, or by coating the above-mentioned thermosetting resin composition onto a metal foil and drying the coated metal foil.

[0026] To make the above-mentioned objectives, technical features and advantages of the present invention more apparent and understandable, the following detailed description is provided with reference to some specific embodiments. Detailed Implementation

[0027] The following describes some specific embodiments of the present invention; however, the present invention can be practiced in many different forms and should not be construed as limited to those set forth in the specification.

[0028] Unless otherwise stated, the terms “a,” “the,” and similar terms used in this specification and claims shall be understood to include both singular and plural forms.

[0029] In this article, the units for weight average molecular weight Mw and number average molecular weight Mn are grams per mole (g / mol).

[0030] The advantages of this invention compared to the prior art lie particularly in that, by controlling the gel permeation chromatography properties of epoxy resins, it improves the solvent solubility, preservation, and processability of epoxy resins. These advantages are surprising because the correlation between the solvent solubility, preservation, and processability of epoxy resins and their GPC properties has never been recognized in the prior art. The following provides a detailed description of the epoxy resin of this invention and its applications.

[0031] 1. Epoxy resin

[0032] 1.1. Structure of epoxy resin

[0033] The epoxy resin in this case is a biphenyl-type epoxy resin. A biphenyl-type epoxy resin refers to a resin that simultaneously possesses a biphenyl structure and an epoxy structure in its molecule. It can be prepared by reacting biphenyl compounds with phenolic compounds to produce biphenyl-type phenolic resin, followed by further epoxidation. In this invention, the epoxy resin has the structure shown in formula (I):

[0034]

[0035] The definitions of Ar, R, m1, m2, and n are as follows.

[0036] [Ar]

[0037] Ar is an aryl group with an epoxy group, and each Ar may be the same or different. Ar may be a divalent group derived from phenolic compounds and further epoxidized. In one embodiment of the invention, each Ar may be an independent divalent group derived from phenol, cresol, resorcinol, or bisphenol compounds and further epoxidized, wherein the epoxidation can be carried out by reaction with epichlorohydrin. Therefore, each Ar may be an independent divalent group derived from phenol, cresol, resorcinol, or bisphenol compounds and further epoxidized.

[0038] R1 and R2 are each an independent hydrogen atom or an organic group.

[0039] [R]

[0040] R stands for promethyl group, i.e., -CH2-, which can be a reaction residue of biphenyl compounds and phenolic compounds.

[0041] [m1 and m2]

[0042] m1 and m2 represent the number of methyl groups on the benzene ring of the biphenyl structure. Since the biphenyl structure of the resin can be derived from biphenyl compounds, m1 and m2 can each be independent integers from 0 to 4, depending on the type of biphenyl compound.

[0043] [n]

[0044] n is greater than 0, which represents the number of repetitions of the structural unit in parentheses, preferably 1 to 400, more specifically 1 to 200, and even more specifically 1 to 100. n can be determined by the molecular weight of the epoxy resin. In one embodiment of the invention, n is 1 to 20, and the value of n is determined by the weight average molecular weight Mw.

[0045] 1.2. Properties of epoxy resin in gel permeation chromatography (GPC)

[0046] When the epoxy resin of this invention is measured by gel permeation chromatography, portions with different n values ​​will produce different signals at different positions in the spectrum. Generally, the smaller the n value, the longer the elution time in the gel permeation chromatography measurement. Therefore, the peak values ​​in the gel permeation chromatography spectrum can be sequentially labeled with their corresponding n values ​​according to the order of elution time. The inventors have discovered that by controlling the peak area ratio of portions representing different n values, the obtained epoxy resin with the structure of formula (I) can have good solvent solubility, preservation, and processability.

[0047] Specifically, when the epoxy resin of the present invention is measured by gel permeation chromatography (GPC), the sum of the peak areas representing the portion where n is less than 5 is A, the sum of the peak areas representing the portion where n is 5 or more is B, and the ratio of B to A (B / A) is 0.40 to 1.40. For example, B / A can be 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 a range consisting of any two of the above values. Studies have found that if the B / A value is below the lower limit of the aforementioned range, the epoxy resin with the structure of formula (I) has poor solvent solubility and is prone to precipitation from the solvent. If the B / A value is above the upper limit of the aforementioned range, the epoxy resin with the structure of formula (I) has poor processability, and the resulting metal foil laminate will have insufficient adhesive, failing to form a complete dielectric layer.

[0048] In this invention, gel permeation chromatography is performed under the following test conditions: epoxy resin is dissolved in tetrahydrofuran at a concentration of 1.25% by weight; separation is performed by sequentially connecting a column C1, two columns C2, and a column C3 at a flow rate of 1.0 mL / min, wherein column C1 is 30 cm long, has an inner diameter of 7.8 mm, and is filled with polystyrene-divinylbenzene with an average particle size of 5 μm and an average pore size of 7.5 nm; each of the columns C2 is 30 cm long, has an inner diameter of 7.8 mm, and is filled 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, has an inner diameter of 7.8 mm, and is filled 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 refractive index detector. In this invention, the peak values ​​in the obtained gel permeation chromatography chromatogram are sequentially labeled with their corresponding n values ​​according to the order of elution time. Then, software is used to calculate the peak area and related proportion of the portion representing each n value, wherein the peak area is calculated as the integral area of ​​the line connecting the start and end points of the peak within a specified range.

[0049] Under the condition that the B / A value is between 0.40 and 1.40, there are no particular restrictions on the signal distribution of the portion representing n less than 5 and the portion representing n greater than 5 in the gel permeation chromatography spectrum. In other words, the portion representing n less than 5 can be composed of one or more sub-parts with n less than 5. The portion representing n greater than 5 can be composed of one or more sub-parts with n greater than 5, more specifically, it can be composed of one or more sub-parts with n from 5 to 400. In one embodiment of the present invention, the portion representing n less than 5 mainly includes the sub-parts with n=1, n=2, n=3, and n=4, and the portion representing n greater than 5 mainly includes the sub-parts with n=5, n=6, and n=7.

[0050] In one embodiment of the present invention, when the epoxy resin is measured by gel permeation chromatography, the sum of the peak areas B representing the portion where n is 5 or more accounts for 30% to 59% of the total area. For example, the sum of the peak areas B representing the portion where n is 5 or more may account for 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% of the total area, or be within a range consisting of any two of the above values.

[0051] In one embodiment of the present invention, when the epoxy resin is measured by gel permeation chromatography, the sum of the peak areas A of the portions where n is less than 5 accounts for 41% to 70% of the total area. For example, the sum of the peak areas A of the portions where n is less than 5 may account for 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% of the total area, or be within a range consisting of any two of the above values.

[0052] In one embodiment of the present invention, when the epoxy resin is measured by gel permeation chromatography, the portion representing n=1 has a peak area a1, and the peak area a1 accounts for more than 20% of the total area, more specifically, 20% to 30% of the total area. For example, the peak area a1 representing the portion representing n=1 may account for 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30% of the total area, or be within a range consisting of any two of the above values.

[0053] The gel permeation chromatography (GPC) properties of the epoxy resin of this invention can be adjusted by controlling the raw material composition or reaction conditions. For example, the aforementioned means of controlling the raw material composition include controlling the molar ratio of phenolic compounds to biphenyl compounds in the raw materials to adjust the B / A value. Generally speaking, the higher the molar ratio of phenolic compounds to biphenyl compounds (moles of phenolic compounds / moles of biphenyl compounds), the lower the B / A value, and vice versa. The aforementioned means of controlling the reaction conditions include controlling the reaction temperature or using a segmented polymerization reaction to prepare the resin. Generally speaking, the higher the reaction temperature, the higher the B / A value, and vice versa.

[0054] 1.3. Other properties of epoxy resins

[0055] Other properties of the epoxy resin of the present invention can be adapted to the required application, provided that the B / A value is between 0.40 and 1.40.

[0056] In one embodiment of the present invention, the weight average molecular weight (Mw) of the epoxy resin is 1600 or more, preferably 1600 to 5000. For example, the weight average molecular weight (Mw) of the epoxy resin may be 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 fall within the range of any two of the above values. The weight-average molecular weight Mw is expressed in grams per mole. The weight-average molecular weight Mw was measured using the aforementioned gel permeation chromatography.

[0057] The number average molecular weight Mn of the epoxy resin can be from 800 to 2000, preferably from 850 to 1600. For example, the number average molecular weight Mn of the epoxy resin can be 800, 850, 900, 950, 1000, 1050, 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450, 1500, 1550, or 1600, or fall within a range consisting of any two of the above values.

[0058] The polydispersity index (PDI) of the epoxy resin (i.e., "Mw / Mn") can be from 1.1 to 4.5, preferably from 1.4 to 4.3. For example, the polydispersity index (PDI) of the epoxy resin can be 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 a range consisting of any two of the above values.

[0059] In one embodiment of the present invention, a 70% by weight solids methyl ethyl ketone solution of epoxy resin has a viscosity of 200 to 800 centipoise at 25°C. For example, the viscosity of a 70% by weight solids methyl ethyl ketone solution of epoxy resin at 25°C may be 200 centipoise, 250 centipoise, 300 centipoise, 350 centipoise, 400 centipoise, 450 centipoise, 500 centipoise, 550 centipoise, 600 centipoise, 650 centipoise, 700 centipoise, 750 centipoise, or 800 centipoise, or a range consisting of any two of the above values.

[0060] In one embodiment of the present invention, the epoxy resin may have an epoxy equivalent of 275 to 300 g / eq. For example, the epoxy equivalent of the epoxy resin may be 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 within a range consisting of any two of the above values. The epoxy equivalent is measured according to ASTM D1652.

[0061] In one embodiment of the present invention, the epoxy resin may have a softening point of 60°C to 95°C. For example, the softening point of the epoxy resin may be 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 a range consisting of any two of the above values.

[0062] 2. Preparation of epoxy resin

[0063] The preparation method of the epoxy resin of this invention is not particularly limited. For example, a phenolic resin can be prepared by reacting a biphenyl compound and a phenolic compound at an appropriate temperature, followed by epoxidation with epichlorohydrin, thereby preparing the epoxy resin. Detailed preparation methods are illustrated in the examples below and will not be repeated here.

[0064] 3. Resin composition

[0065] The epoxy resin of this invention possesses excellent solvent solubility and preservation properties, thus it can be uniformly mixed with solvents and, if desired, additives, and dissolved or dispersed in solvents to form slurries, colloidal groups, varnishes, etc. Therefore, this invention also provides a thermosetting resin composition comprising the above-mentioned epoxy resin and solvent.

[0066] The solvent can be any inert solvent that can dissolve or disperse the components of the resin composition but does not react with them, such as aromatic hydrocarbons, ethers, alcohols, or ketones. Examples of such solvents include, but are not limited to: acetone, butanone, cyclohexanone, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, propylene glycol methyl ether, γ-butyrolactone, dimethylformamide (DMF), dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP). The aforementioned solvents can be used alone or in combination. There is no particular limitation on the amount of solvent used; in principle, it is sufficient to ensure that the components of the resin composition are uniformly dissolved or dispersed therein.

[0067] Without departing from the technical principles of this invention, the resin composition of this invention may further include selected components as needed to adaptively improve the processability of the resin composition during manufacturing, or to improve the physicochemical properties of electronic materials made from the resin composition. The selected components include, but are not limited to, additives selected from the following group: curing agents, curing accelerators, elastomers, fillers, dispersants, toughening agents, viscosity modifiers, flame retardants, plasticizers, and coupling agents. The aforementioned additives may be used alone or in any combination.

[0068] 4. Prepreg and metal foil laminate

[0069] This invention also provides a semi-cured sheet made from the above-described thermosetting resin composition, wherein the sheet is prepared by impregnating a substrate with the flame-retardant composition described above or coating the above-described thermosetting resin composition onto a substrate, and then drying the impregnated or coated substrate. The substrate may be a reinforcing material. Generally, the reinforcing material includes, but is 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, NE-glass, S-glass, L-glass, D-glass, T-glass, Q-glass, UN-glass, 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, polyimide, polyamide (e.g., Kevlar), polyester, liquid crystal polymers (e.g., liquid crystal polyester), polytetrafluoroethylene, ultra-high molecular weight polyethylene (UHMWPE), and high-modulus polypropylene (HMPP). Reinforcing materials can take the form of, but are not limited to, woven fabrics, non-woven fabrics, rovings, woven felt, and surface felt.

[0070] Furthermore, the present invention also provides a metal foil laminate made from the aforementioned prepreg, comprising a dielectric layer and a metal layer located on at least one surface of the dielectric layer, wherein the dielectric layer is formed from the aforementioned prepreg and the metal layer is formed from a metal foil. Specifically, multiple layers of the aforementioned prepreg can be stacked, and a metal foil (such as a copper foil) is stacked on at least one outer surface of the dielectric layer formed by the stacked prepregs to provide a laminate, and the laminate is subjected to a hot-pressing operation to obtain a metal foil laminate. Alternatively, the flame-retardant composition of the present invention can be directly coated onto a metal foil and the coated metal foil can be dried to obtain a metal foil laminate.

[0071] The outer metal foil of the aforementioned metal foil laminate can be further patterned to produce a printed circuit board.

[0072] 5. Examples

[0073] 5.1 Measurement Method

[0074] [Gel Permeation Chromatography (GPC) Test]

[0075] The prepared epoxy resin was dissolved in tetrahydrofuran at a concentration of 1.25% by weight, and then fed into a series of tubular columns C1 (model: TOSOH TSKgel G3000HxL), C2 (model: TOSOH TSKgel G2000HxL), and C3 (model: TOSOH TSKgel G3000HxL) at a flow rate of 1.0 mL / min at 40 °C. Separation was performed using G1000HxL columns. Column C1 was 30 cm long with an inner diameter of 7.8 mm and filled with polystyrene-divinylbenzene with an average particle size of 5 μm and an average pore size of 7.5 nm. Columns C2 and C3 were also 30 cm long with an inner diameter of 7.8 mm and filled with polystyrene-divinylbenzene with an average particle size of 5 μm and an average pore size of 2 nm. Column C3 was 30 cm long with an inner diameter of 7.8 mm and filled with polystyrene-divinylbenzene with an average particle size of 5 μm and an average pore size of 1.5 nm. Samples were collected and analyzed using a Waters 2414RI refractive index detector. The peak values ​​in the resulting gel permeation chromatography chromatograms were sequentially labeled with their corresponding n-values ​​according to elution time. Then, the peak area and related proportions representing each n-value were calculated using the SISC32 software. The peak area was calculated as the integral area of ​​the line connecting the start and end points of the peak within a specified range.

[0076] [Viscosity Test]

[0077] The prepared epoxy resin was formulated into a 70% by weight solids solution of methyl ethyl ketone and placed in a constant temperature water bath at 25°C for 2 hours. The viscosity was then measured using a Brookfield viscometer, with the unit of viscosity being centipoise.

[0078] [Epoxy Equivalent Test]

[0079] The epoxy equivalent of the prepared epoxy resin was measured according to ASTM D 1652. The unit of epoxy equivalent is g / eq.

[0080] [Softening Point Test]

[0081] The softening point of the prepared epoxy resin was measured according to JIS K 7234. The unit of softening point is °C.

[0082] [Solvent Solubility and Preservation Test]

[0083] The prepared epoxy resin was formulated into a 70% by weight solids solution of methyl ethyl ketone and placed in a refrigerator at 5°C. The solution was observed daily for any precipitation and the time of precipitation was recorded. If no precipitation occurred after 70 days, it was recorded as "no precipitation".

[0084] [Processability Test]

[0085] The prepared epoxy resin was combined with phenolic resin (Changchun PF8110) to formulate a varnish with an epoxy equivalent to hydroxyl equivalent ratio of 1, and its gel time was controlled to be 100 to 120 seconds. A fiberglass cloth was impregnated in the varnish and then dried to prepare a fiberglass cloth prepreg. Five fiberglass cloth prepregs were stacked, and a copper foil was placed on the outermost layer on each side, followed by hot pressing. After hot pressing, the copper foil was removed by etching, and the surface of the fiberglass cloth was observed for any missing adhesive. If missing adhesive was observed, the processability test was not passed and recorded as "×"; if no missing adhesive was observed, the processability test was passed and recorded as "○".

[0086] 5.2. Preparation of epoxy resin

[0087] [Example 1]

[0088] In a four-necked flask equipped with a stirrer, thermometer, and condenser, 275.3 g of phenol and 1 g of p-toluenesulfonic acid were added. 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, followed by washing with water. After washing, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, yielding a phenolic resin.

[0089] 100 g of the previously prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were uniformly mixed. The temperature was raised to 55°C, and 40 g of potassium hydroxide was added in batches over 120 minutes. The reaction was then carried out at 55°C for 2 hours, followed by raising the temperature to 70°C and reacting at 70°C for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The resulting filtrate was added to 560 g of methyl isobutyl ketone and dissolved. Then, the temperature was raised to 55°C, and 2 g of 30% (w / w) sodium hydroxide aqueous solution was added, and the reaction was carried out for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, yielding epoxy resin. The obtained 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.

[0090] [Example 2]

[0091] In a four-necked flask equipped with a stirrer, thermometer, and condenser, 29.8 g of phenol and 1 g of p-toluenesulfonic acid were added. 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. Then, 94.1 g of phenol and 84.5 g of 4,4'-bis(chloromethyl)-1,1'-biphenyl were added again, 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 the mixture was washed with water. After washing, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, yielding a phenolic resin.

[0092] 100 g of the previously prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were uniformly mixed. The temperature was raised to 55°C, and 40 g of potassium hydroxide was added in batches over 120 minutes. The reaction was then carried out at 55°C for 2 hours, followed by raising the temperature to 70°C and reacting at 70°C for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The resulting filtrate was added to 560 g of methyl isobutyl ketone and dissolved. Then, the temperature was raised to 55°C, and 2 g of 30% (w / w) sodium hydroxide aqueous solution was added, and the reaction was carried out for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, yielding epoxy resin. The obtained 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.

[0093] [Example 3]

[0094] In a four-necked flask equipped with a stirrer, thermometer, and condenser, 275.3 g of phenol and 1 g of p-toluenesulfonic acid were added. 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, followed by washing with water. After washing, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, yielding a phenolic resin.

[0095] 100 g of the previously prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were uniformly mixed. The temperature was raised to 55°C, and 40 g of potassium hydroxide was added in batches over 120 minutes. The reaction was then carried out at 55°C for 2 hours, followed by raising the temperature to 70°C and reacting at 70°C for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The resulting filtrate was added to 560 g of methyl isobutyl ketone and dissolved. Then, the temperature was raised to 55°C, and 2 g of 30% (w / w) sodium hydroxide aqueous solution was added, and the reaction was carried out for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, yielding epoxy resin. The obtained 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.

[0096] [Example 4]

[0097] In a four-necked flask equipped with a stirrer, thermometer, and condenser, 89.2 g of phenol and 1 g of p-toluenesulfonic acid were added. 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. Then, 336.0 g of phenol and 280.0 g of 4,4'-bis(chloromethyl)-1,1'-biphenyl were added again, 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, followed by washing with water. After washing, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, yielding a phenolic resin.

[0098] 100 g of the previously prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were uniformly mixed. The temperature was raised to 55°C, and 40 g of potassium hydroxide was added in batches over 120 minutes. The reaction was then carried out at 55°C for 2 hours, followed by raising the temperature to 70°C and reacting at 70°C for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The resulting filtrate was added to 560 g of methyl isobutyl ketone and dissolved. Then, the temperature was raised to 55°C, and 2 g of 30% (w / w) sodium hydroxide aqueous solution was added, and the reaction was carried out for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, yielding epoxy resin. The obtained 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.

[0099] [Example 5]

[0100] In a four-necked flask equipped with a stirrer, thermometer, and condenser, 70.1 g of phenol and 1 g of p-toluenesulfonic acid were added. 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. Then, 247.3 g of phenol and 220.0 g of 4,4'-bis(chloromethyl)-1,1'-biphenyl were added again, 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, followed by washing with water. After washing, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, yielding a phenolic resin.

[0101] 100 g of the previously prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were uniformly mixed. The temperature was raised to 55°C, and 40 g of potassium hydroxide was added in batches over 120 minutes. The reaction was then carried out at 55°C for 2 hours, followed by raising the temperature to 70°C and reacting at 70°C for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The resulting filtrate was added to 560 g of methyl isobutyl ketone and dissolved. Then, the temperature was raised to 55°C, and 2 g of 30% (w / w) sodium hydroxide aqueous solution was added, and the reaction was carried out for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, yielding epoxy resin. The obtained 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.

[0102] [Example 6]

[0103] In a four-necked flask equipped with a stirrer, thermometer, and condenser, 129.2 g of phenol and 1 g of p-toluenesulfonic acid were added. 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, followed by washing with water. After washing, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, yielding a phenolic resin.

[0104] 100 g of the previously prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were uniformly mixed. The temperature was raised to 55°C, and 40 g of potassium hydroxide was added in batches over 120 minutes. The reaction was then carried out at 55°C for 2 hours, followed by raising the temperature to 70°C and reacting at 70°C for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The resulting filtrate was added to 560 g of methyl isobutyl ketone and dissolved. Then, the temperature was raised to 55°C, and 2 g of 30% (w / w) sodium hydroxide aqueous solution was added, and the reaction was carried out for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, yielding epoxy resin. The obtained 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.

[0105] [Comparative Example 1]

[0106] In a four-necked flask equipped with a stirrer, thermometer, and condenser, 526.1 g of phenol and 1 g of p-toluenesulfonic acid were added. 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, followed by washing with water. After washing, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, yielding a phenolic resin.

[0107] 100 g of the previously prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were uniformly mixed. The temperature was raised to 55°C, and 40 g of potassium hydroxide was added in batches over 120 minutes. The reaction was then carried out at 55°C for 2 hours, followed by raising the temperature to 70°C and reacting at 70°C for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The resulting filtrate was added to 560 g of methyl isobutyl ketone and dissolved. Then, the temperature was raised to 55°C, and 2 g of 30% (w / w) sodium hydroxide aqueous solution was added, and the reaction was carried out for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, yielding epoxy resin. The obtained 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.

[0108] [Comparative Example 2]

[0109] In a four-necked flask equipped with a stirrer, thermometer, and condenser, 182.7 g of phenol and 1 g of p-toluenesulfonic acid were added. 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, followed by washing with water. After washing, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, yielding a phenolic resin.

[0110] 100 g of the previously prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were uniformly mixed. The temperature was raised to 55°C, and 40 g of potassium hydroxide was added in batches over 120 minutes. The reaction was then carried out at 55°C for 2 hours, followed by raising the temperature to 70°C and reacting at 70°C for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The resulting filtrate was added to 560 g of methyl isobutyl ketone and dissolved. Then, the temperature was raised to 55°C, and 2 g of 30% (w / w) sodium hydroxide aqueous solution was added, and the reaction was carried out for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, yielding epoxy resin. The obtained 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.

[0111] [Comparative Example 3]

[0112] In a four-necked flask equipped with a stirrer, thermometer, and condenser, 129.2 g of phenol and 1 g of p-toluenesulfonic acid were added. 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, followed by washing with water. After washing, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, yielding a phenolic resin.

[0113] 100 g of the previously prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were uniformly mixed. The temperature was raised to 55°C, and 40 g of potassium hydroxide was added in batches over 120 minutes. The reaction was then carried out at 55°C for 2 hours, followed by raising the temperature to 70°C and reacting at 70°C for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The resulting filtrate was added to 560 g of methyl isobutyl ketone and dissolved. Then, the temperature was raised to 55°C, and 2 g of 30% (w / w) sodium hydroxide aqueous solution was added, and the reaction was carried out for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, yielding epoxy resin. The obtained 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.

[0114] [Comparative Example 4]

[0115] In a four-necked flask equipped with a stirrer, thermometer, and condenser, 129.2 g of phenol and 1 g of p-toluenesulfonic acid were added. 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, followed by washing with water. After washing, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, yielding a phenolic resin.

[0116] 100 g of the previously prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were uniformly mixed. The temperature was raised to 55°C, and 40 g of potassium hydroxide was added in batches over 120 minutes. The reaction was then carried out at 55°C for 2 hours, followed by raising the temperature to 70°C and reacting at 70°C for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The resulting filtrate was added to 560 g of methyl isobutyl ketone and dissolved. Then, the temperature was raised to 55°C, and 2 g of 30% (w / w) sodium hydroxide aqueous solution was added, and the reaction was carried out for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, yielding epoxy resin. The obtained 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.

[0117] [Comparative Example 5]

[0118] In a four-necked flask equipped with a stirrer, thermometer, and condenser, 129.2 g of phenol and 1 g of p-toluenesulfonic acid were added. 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, followed by washing with water. After washing, the resulting oil layer was heated under reduced pressure to remove unreacted phenol, yielding a phenolic resin.

[0119] 100 g of the previously prepared phenolic resin, 452 g of epichlorohydrin, and 113 g of propylene glycol methyl ether were uniformly mixed. The temperature was raised to 55°C, and 40 g of potassium hydroxide was added in batches over 120 minutes. The reaction was then carried out at 55°C for 2 hours, followed by raising the temperature to 70°C and reacting at 70°C for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove excess epichlorohydrin. The resulting filtrate was added to 560 g of methyl isobutyl ketone and dissolved. Then, the temperature was raised to 55°C, and 2 g of 30% (w / w) sodium hydroxide aqueous solution was added, and the reaction was carried out for 1 hour. After the reaction was completed, pure water was added and the mixture was repeatedly washed until the product was neutral. After washing, the resulting oil layer was distilled under reduced pressure to remove methyl isobutyl ketone, yielding epoxy resin. The obtained 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.

[0120] 5.3. Properties Testing of Epoxy Resin

[0121] The properties of the epoxy resins of Examples 1 to 6 and Comparative Examples 1 to 5, including gel permeation chromatography properties, viscosity, epoxy equivalent, softening point, solvent solubility and preservation, and processability, were measured according to the measurement methods described above, and the results are recorded in Tables 1-1 and 1-2 below.

[0122] Table 1-1

[0123]

[0124] Table 1-2

[0125]

[0126]

[0127] As shown in Tables 1-1 and 1-2, the epoxy resins of Examples 1 to 6 of the present invention all have a precipitation time of more than 18 days in the solvent, indicating good solvent solubility and preservation, and no glue shortage, indicating good processability. In contrast, the epoxy resins of Comparative Examples 1 to 5 cannot simultaneously provide the above-mentioned excellent properties. Comparative Examples 1 and 2 show that if the B / A value is lower than the range specified in the present invention, the epoxy resin precipitates from the solvent in a very short time, indicating poor solvent solubility and preservation. Comparative Examples 3 to 5 show that if the B / A value is higher than the range specified in the present invention, the epoxy resin will produce glue shortage and cannot be formed into the desired shape, indicating poor processability.

[0128] The above embodiments are merely illustrative of the principles and effects of the present invention and to illustrate its technical features, and are not intended to limit the scope of protection of the present invention. Any changes or arrangements that can be easily made by those skilled in the art without departing from the technical principles of the present invention are within the scope of the present invention. Therefore, the scope of protection of the present invention is as set forth in the claims.

Claims

1. An epoxy resin, characterized by, which is represented by the following formula (I), wherein Ar is an aromatic group having an epoxy group, each Ar can be the same or different; R is a methylene group; m1 and m2 are each independently an integer of 0 to 4; n is greater than 0; and the sum of the peak areas of the portion in which n is less than 5 is A, the sum of the peak areas of the portion in which n is 5 or more is B, and the ratio (B / A) of B to A is 0.40 to 1.40, when the epoxy resin is measured by gel permeation chromatography.

2. The epoxy resin according to claim 1, wherein each Ar is independently a divalent group derived from a phenol, cresol, resorcinol, or bisphenol compound, and further subjected to epoxidation.

3. The epoxy resin of claim 1, wherein, n is 1 to 400.

4. The epoxy resin of claim 1, wherein, the sum of the peak areas of the portion in which n is 5 or more is B, and B is 30% to 59% of the total area, when the epoxy resin is measured by gel permeation chromatography.

5. The epoxy resin of claim 1, wherein, the sum of the peak areas of the portion in which n is less than 5 is A, and A is 41% to 70% of the total area, when the epoxy resin is measured by gel permeation chromatography.

6. The epoxy resin according to any one of claims 1 to 5, wherein The gel permeation chromatography is performed under the following test conditions: the epoxy resin is dissolved in tetrahydrofuran at a concentration of 1.25% by weight; separation is performed by feeding at a flow rate of 1.0 mL / min into a column C1, two columns C2, and a column C3 connected in series, wherein the column C1 has a length of 30 cm, an inner diameter of 7.8 mm, and is filled with polystyrene-divinylbenzene having an average particle diameter of 5 μm and an average pore diameter of 7.5 nm, each of the columns C2 has a length of 30 cm, an inner diameter of 7.8 mm, and is filled with polystyrene-divinylbenzene having an average particle diameter of 5 μm and an average pore diameter of 2 nm, and the column C3 has a length of 30 cm, an inner diameter of 7.8 mm, and is filled with polystyrene-divinylbenzene having an average particle diameter of 5 μm and an average pore diameter of 1.5 nm; The sample is collected and analyzed with a refractive index detector.

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

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

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

10. A thermosetting resin composition, characterized by comprising: It comprises the epoxy resin of any one of claims 1 to 9 and a solvent.

11. The thermosetting resin composition according to claim 10, wherein It further comprises an additive selected from the group consisting of a hardener, a hardening accelerator, an elastomer, a filler, a dispersant, a flexibilizer, a viscosity adjuster, a flame retardant, a plasticizer, a coupling agent, and combinations thereof.

12. A prepreg, characterized by, It is produced by impregnating or coating a substrate with the thermosetting resin composition of claim 10 or 11, and drying the impregnated or coated substrate.

13. A metal foil laminate, characterized by comprising: It is produced by laminating the prepreg of claim 12 with a metal foil, or by coating a metal foil with the thermosetting resin composition of claim 10 or 11 and drying the coated metal foil.

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