Bismaleimides and methods for making the same

Abstract

The present invention provides a bismaleimide which is obtained by maleimiding the amino group of a dimer diamine, and in which the mixed solubility and handling properties are sufficiently improved when mixed with other agents such as a curable resin, and a method for producing the same. The present invention relates to a bismaleimide which is obtained by maleimiding the amino group of a dimer diamine, and has the following characteristics. 1) The acid value of the bismaleimide is 2 mg-KOH / g or less. 2) The viscosity of the bismaleimide measured at 25°C using a B-type viscometer is 3.0 Pa-s or less.

Description

Technical Field

[0001] This invention relates to a bismaleimide and its manufacturing method. Background Technology

[0002] Electronic components used in mobile phones, smartphones, laptops, and other electronic devices are increasingly characterized by high-density integration and mounting. For resin materials such as adhesives and sealants used in these components, materials with low water absorption, excellent reliability, and high heat resistance are required. As a component of compositions used in these adhesives and sealants, a method using bismaleimide is known. The bismaleimide is formed by maleimizing the amino group of a dimer diamine (an aliphatic diamine derived from a dimer acid with 24 to 48 carbon atoms, hereinafter sometimes simply referred to as "DDA"). For example, Patent Document 1 discloses a method using maleimide as a component of an adhesive composition for mounting LED elements. Patent Document 2 discloses a method using bismaleimide as a component of an anisotropic conductive adhesive composition for printed wiring substrates.

[0003] Aliphatic bismaleimides can be obtained by known methods disclosed in patent documents 3-5, etc. Specifically, they can be manufactured, for example, by reacting a diamine with maleic anhydride in a solvent under an acid catalyst to imide and then purify the product. These bismaleimides are also commercially available from Designer Molecules Inc. (sometimes abbreviated as DMI) under trade names such as BMI-689, BMI-1500, BMI-1700, and BMI-3000. Because these aliphatic bismaleimides contain trace amounts of unclosed ring-forming acids such as maleamic acid, fumaric acid, and Michael adducts (compounds formed by the Michael addition reaction of MAA with an amine, which further reacts with maleic anhydride), their acid values ​​significantly exceed 2 mg-KOH / g. Using these acidic components in electronic components poses a problem of negatively impacting electrical properties.

[0004] As a solution to the above problems, Patent Document 6 describes the following manufacturing method: after manufacturing bismaleimide (crude bismaleimide) with a high acid value and residual acid components, maleamic acid and other impurities are removed by reacting with a carbodiimide compound (CDI), thereby reducing the acid value to below 2 mg-KOH / g.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2017-31227

[0008] Patent Document 2: Japanese Patent Application Publication No. 2015-193725

[0009] Patent Document 3: U.S. Statutory Invention Registration No. H424

[0010] Patent Document 4: U.S. Publication No. 20080262191

[0011] Patent Document 5: Japanese Patent Publication No. 10-505599

[0012] Patent Document 6: Japanese Patent Application Publication No. 2018-115156

[0013] Patent Document 7: Japanese Patent Application Publication No. 2014-132066 Summary of the Invention

[0014] However, even with bismaleimides whose acid value is reduced to below 2 mg-KO H / g by minimizing impurities from acids such as maleamide, problems still exist. Specifically, because the viscosity of the bismaleimide is not sufficiently reduced, it is difficult to mix with other agents such as curing resin compositions, thus impairing workability.

[0015] On the other hand, in order to increase the yield during the maleimide reaction, basic compounds such as aliphatic tertiary amines are sometimes coexisted (e.g., Patent Document 7), but even in such cases, it is still impossible to sufficiently reduce the viscosity of bismaleimide.

[0016] Therefore, the present invention was made to solve the above-mentioned problems, and its object is to provide a bismaleimide that, while sufficiently reducing the acid content from by-products, further sufficiently reduces viscosity.

[0017] The inventors conducted in-depth research and found that the above-mentioned problems could be solved by using two specific acid catalysts to produce crude bismaleimide and then reacting it with a carbodiimide compound, thus completing the present invention.

[0018] The present invention is based on the following: A bismaleimide, which is formed by maleimidation of the amino group of a dimer diamine, and has the following characteristics.

[0019] 1) The acid value of the above-mentioned bismaleimide is less than 2 mg-KOH / g.

[0020] 2) The viscosity of the above-mentioned bismaleimide, measured by a type B viscometer at 25°C, is below 3.0 Pa·s.

[0021] This invention further relates to the above-mentioned bismaleimide, in 1In H-NMR, when comparing the integral value (A) of the peak corresponding to the proton of the methylene group directly bonded to the nitrogen atom of the maleimide group and the integral value (B) of the peak corresponding to the vinyl proton of the maleimide group, the B / A ratio exceeds 0.80.

[0022] The present invention further relates to a method for manufacturing the above-mentioned bismaleimide, characterized by comprising the following steps.

[0023] 1) A process of preparing a crude bismaleimide solution with an acid value exceeding 2 mg-KO H / g by using an acid with a pKa less than 1 and an acid with a pKa greater than 1 as catalysts, and using the above catalysts with a molar percentage of more than 15 mol% relative to the dimer diamine.

[0024] 2) A process in which the acid value is reduced to below 2 mg-KOH / g by reacting the acid component in the above solution with a carbodiimide compound (CDI).

[0025] The bismaleimide of the present invention has a low viscosity and its acid value is sufficiently reduced, thus exhibiting good miscibility and workability when combined with other agents such as curable resins. Furthermore, although the reason for making the bismaleimide of the present invention low in viscosity and low in acid value is not clearly understood, its reactivity is significantly improved, a phenomenon that is advantageous industrially when combined with other agents. Therefore, it is suitable for use as a component in sealing material compositions, adhesive compositions, etc., used in the manufacture of electronic components using semiconductors, etc. Attached Figure Description

[0026] Figure 1 It is the bismaleimide of Example 1. 1 H-NMR spectrum. Detailed Implementation

[0027] The present invention will now be described in detail. The bismaleimide of the present invention has an acid value of less than 2 mg-KOH / g and a viscosity of less than 3.0 Pa·s as measured by a type B viscometer at 25°C.

[0028] Here, acid value is a parameter that quantitatively expresses the amount of residual acid in the above-mentioned bismaleimide, and can be determined by neutralization titration according to JIS K0070 (1992). The acid value of the bismaleimide of the present invention is preferably 2 mg-OH / g or less, more preferably 1.7 mg-KOH / g or less, even more preferably 1 mg-KOH / g or less, and particularly preferably 0.5 mg-KOH / g or less.

[0029] The viscosity of the bismaleimide of the present invention, measured using a type B viscometer at 25°C, needs to be 3.0 Pa·s or less, preferably 2.5 Pa·s or less, and more preferably 2.0 Pa·s or less. In this way, the bismaleimide exhibits high miscibility when combined with other agents, ensuring good operability.

[0030] The bismaleimide of the present invention has a chemical structure formed by the dehydration condensation of a dimer diamine (DDA) and maleic acid. Here, DDA refers to an aliphatic diamine derived from a dimer acid with 24 to 48 carbon atoms. Commercially available DDA products such as "Versa mine551" manufactured by Cognis Japan and "Priamine 1074" and "Priamine 1075" manufactured by Croda can be used.

[0031] In the bismaleimide manufacturing method of the present invention, DDA is first reacted with maleic anhydride in a solvent in the presence of two acid catalysts to obtain maleamic acid. Then, the amic acid portion of the maleamic acid is imidized to form bismaleimide. At this time, a crude bismaleimide solution with an acid value exceeding 2 mg-KOH / g, containing residual byproducts from the acid, is typically obtained. The maleic anhydride, which is part of the reaction matrix, is used in an equivalent amount relative to the amino group of DDA. Imidization is preferably performed at the reflux temperature of the solvent used, while azeotropically removing the water generated during imidization. The reaction temperature for the imidization is preferably below 150°C, more preferably below 130°C. The reaction time for imidization is preferably 2 to 12 hours, more preferably 4 to 10 hours. If the reaction time exceeds 12 hours, side reactions such as the formation of vinyl polymers may easily occur. In addition, if the time is less than 2 hours, the imidization reaction is not fully carried out, making it difficult to clean and sometimes resulting in a reduced yield.

[0032] As an acid catalyst, two acid catalysts are required. The first acid catalyst uses an acid dissociation constant (pKa) less than 1, and the second acid catalyst uses an acid catalyst with a pKa greater than 1. It should be noted that for acids with two or more nucleotides, the first acid dissociation constant (pKa1) is used as the pKa of that acid for the selection of the acid catalyst.

[0033] Specifically, inorganic acids such as sulfuric acid (pKa: -3) and nitric acid (pKa: -1.4) and organic sulfonic acids such as methanesulfonic acid (pKa: -2.6) and toluenesulfonic acid (pKa: -2.8) can be used as the primary acid catalyst. Among them, methanesulfonic acid and toluenesulfonic acid are preferred.

[0034] As the second acid catalyst, acid catalysts with pKa of 1 to 7 are preferred, and examples include various organic carboxylic acids such as aliphatic carboxylic acids. Examples of aliphatic carboxylic acids as the second acid catalyst include acetic acid (pKa: 4.6), propionic acid (pKa: 4.9), maleic acid (pKa: 1.8), succinic acid (pKa: 4.2), malic acid (pKa: 3.4), and fumaric acid (pKa: 3.0). Furthermore, aliphatic acid anhydrides can be used as chemical equivalents of aliphatic carboxylic acids as the second acid catalyst. Examples of aliphatic acid anhydrides include anhydrides of acetic acid, propionic acid, maleic acid, succinic acid, and malic acid. Among the above-mentioned carboxylic acids or anhydrides, maleic acid, malic acid, acetic acid, and their anhydrides are preferred.

[0035] The total amount of the two acid catalysts used needs to be at least 115 mol% relative to the molar amount of DDA, preferably at least 150 mol%. If the total amount of acid catalysts used is less than 115 mol%, the viscosity reduction effect is insufficient. Furthermore, if the amount of acid catalyst used is too high, the effect becomes saturated; therefore, considering economy, it is preferable to use 650 mol% or less, and more preferably 520 mol% or less. The amounts of the first and second acid catalysts used can be appropriately determined within the above-mentioned total amount range. As for the amount of the first acid catalyst used, it is preferably in the range of 55 mol% to 285 mol% relative to the molar amount of DDA, more preferably in the range of 85 mol% to 230 mol%. Two or more first acid catalysts can be used; in this case, their total amount used only needs to be within the above-mentioned range for the amount of the first acid catalyst. The amount of the second acid catalyst used is preferably in the range of 55 mol% to 365 mol% relative to the molar amount of DDA, more preferably in the range of 65 mol% to 285 mol%. Two or more second acid catalysts can be used; in this case, their total amount used only needs to be within the above-mentioned range for the amount of the second acid catalyst. The ratio of the first acid catalyst to the second acid catalyst is not particularly limited, but it is preferably in the range of (first acid catalyst) / (second acid catalyst) = 2 / 8 to 8 / 2 (molar ratio), more preferably in the range of 3 / 7 to 7 / 3, and even more preferably in the range of 4 / 6 to 6 / 4. Particularly when maleic anhydride is used not only as a raw material for bismaleimide but also as a second acid catalyst, the amount of the second acid catalyst relative to the aforementioned molar amount of DDA is calculated by subtracting a molar amount equal to twice the molar amount of DDA from the total amount of maleic anhydride used (i.e., the total amount of maleic anhydride used as a raw material for bismaleimide and the total amount of maleic anhydride used as a second acid catalyst). This value only needs to be within the range of the aforementioned amount of the second acid catalyst relative to the molar amount of DDA.

[0036] By using specific amounts of two acid catalysts in combination to promote the maleimide reaction and suppress byproducts such as Michael adducts and vinyl polymers in the production process of crude bismaleimide, a low-viscosity crude bismaleimide solution can be obtained.

[0037] In maleimide reactions, basic compounds (e.g., aliphatic tertiary amines such as triethylamine) are sometimes used in the presence of maleimide to improve yield. However, it is believed that such basic compounds form salts through neutralization reactions with acid catalysts, thereby deactivating a portion of the added acid catalyst. Therefore, in the maleimide reaction of the present invention, it is preferable not to use basic compounds. When basic compounds are used in the presence of maleimide, the total amount of the two acid catalysts relative to the molar amount of DDA is the value obtained by subtracting the amount of basic compound relative to the molar amount of DDA from this total amount. This value is acceptable as long as it falls within the range of the total amount of the two acid catalysts relative to the molar amount of DDA.

[0038] The solvent used in the reaction is not limited to any solvent that dissolves the product bismaleimide. Preferably, amide solvents such as N-methylpyrrolidone (NMP) and dimethylacetamide (DMAc); hydrocarbon solvents such as toluene and xylene; and ether solvents such as ethylene glycol dimethyl ether and diethylene glycol dimethyl ether are used. These solvents can be used alone or in combination of two or more. Among these, a mixed solvent consisting of an amide solvent and a hydrocarbon solvent is preferred. The mixing ratio is not particularly limited, but to achieve the preferred reaction temperature of 150°C or below, a mass ratio of (amide solvent) / (hydrocarbon solvent) of 5 / 5 to 1 / 9 is preferred.

[0039] The concentration of solid components during the reaction is preferably 20-70% by mass, more preferably 30-70% by mass. It should be noted that the concentration of solid components refers to the total mass of the reaction matrix (DDA and maleic anhydride) relative to the total mass of the solution (the total mass of the reaction matrix, solvent, and acid catalyst).

[0040] Next, the crude bismaleimide solution obtained in the above manner is purified to obtain bismaleimide with an acid value of less than 2 mg-KOH / g. That is, in a solvent, CDI is reacted with the acid component in the bismaleimide to achieve an acid value of less than 2 mg-KOH / g. The amount of CDI used corresponds to the acid value of the crude bismaleimide; there is no particular limitation as long as the carbodiimide group is at least one equivalent to the acid value, and it can be appropriately selected in the range of 1 to 1.2 equivalents. The reaction temperature is preferably 30°C to 100°C, more preferably 40°C to 70°C. The concentration of the solid component of the crude bismaleimide relative to the mass of the solution is preferably 20 to 70% by mass, more preferably 30 to 70% by mass. Through this reaction, the acid component in the bismaleimide reacts with CDI, producing a urea derivative of CDI as a byproduct. This urea derivative of CDI can be removed by washing the reaction solution with water, alcohol (methanol, ethanol, etc.), i.e., by solvent extraction. The solvent is then distilled off to obtain bismaleimide with an acid value of less than 2 mg-KOH / g. The acid value of the purified bismaleimide is more preferably less than 1 mg-KOH / g, and even more preferably less than 0.5 mg-KOH / g.

[0041] As a CDI that reacts with the acidic component in crude bismaleimide, N,N′-diisopropylcarbodiimide (DIC), 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), bis(2,6-diisopropylphenyl)carbodiimide, diphenylcarbodiimide, di-β-naphthylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, tert-butylisopropylcarbodiimide, di-tert-butylcarbodiimide, N,N′-dicyclohexylcarbodiimide (DCC), poly(1,6-hexamethylenecarbodiimide), poly(4,4′-methylenebiscyclohexylcarbodiimide), poly(1,3-cyclohexylenecarbodiimide), poly(1,4-cyclohexylenecarbodiimide) Cyclohexylcarbodiimide, poly(4,4′-dicyclohexylmethanecarbodiimide), poly(4,4′-diphenylmethanecarbodiimide), poly(3,3′-dimethyl-4,4′-diphenylmethanecarbodiimide), poly(naphthylcarbodiimide), poly(p-phenylenecarbodiimide), poly(m-phenylenecarbodiimide), poly(tolylcarbodiimide), poly(methyl-diisopropylphenylenecarbodiimide), poly(1,3,5-triisopropylphenylenecarbodiimide), poly(1,3,5-triisopropylbenzene and 1,5-diisopropylphenylenecarbodiimide), poly(triethylphenylenecarbodiimide), poly(triisopropylphenylenecarbodiimide), poly(diisopropylcarbodiimide), etc., preferably DIC or EDC. These CDIs can be used alone or in combination of two or more.

[0042] There are no restrictions on the solvents used in the reaction of the acid components in crude bismaleimide with CDI, but hydrocarbon solvents such as toluene, xylene (o-xylene, m-xylene, p-xylene), ethylbenzene, mesitylene, and naphtha are preferred.

[0043] The bismaleimide obtained in this manner is preferably of the following type. 1 The NMR integral ratio (B / A) of H-NMR is greater than 0.80, more preferably 0.82 or higher. Furthermore, B / A is more preferably 0.85 or higher, and even more preferably 0.87 or higher. Here, A is the integral value of the peak corresponding to the proton of the methylene group directly bonded to the nitrogen atom of the maleimide group, and B is the integral value of the peak corresponding to the vinyl proton of the maleimide group. A higher integral ratio indicates a higher maleimide group content in the bismaleimide, meaning that when DDA reacts with maleic acid, the formation of Michael adducts and vinyl polymers, which are byproducts, can be suppressed. This results in a reduction of substances that contribute to viscosity increases.

[0044] Here, the NMR measurement conditions are as follows. (Refer to...) Figure 1 )

[0045] < 1 H-NMR measurement conditions >

[0046] Apparatus: Nuclear Magnetic Resonance Imaging System (manufactured by JEOL Ltd.: Model ECA500)

[0047] Frequency: 500.16MHz

[0048] Reference material: Tetramethylsilane

[0049] Solvent: Dichloroform

[0050] Measurement temperature: 25℃

[0051] Under the above measurement conditions, the chemical shift of the peak corresponding to the proton of the methylene group directly bonded to the nitrogen atom of the maleimide group of bismaleimide is approximately 3.5 ppm. Figure 1 Peak 1). Additionally, the chemical shift of the peak corresponding to the vinyl proton of the maleimide group in bismaleimide is approximately 6.7 ppm ( Figure 1 Peak 2). Therefore, by reading the integral values ​​of these peaks from the NMR spectrum, the NMR integral ratio can be calculated.

[0052] The molecular weight of the bismaleimide of the present invention, as determined by GPC as described later, is preferably in the range of 1400 to 1800, more preferably in the range of 1450 to 1700, even more preferably in the range of 1450 to 1620, and even more preferably in the range of 1450 to 1520.

[0053] The bismaleimide of the present invention exhibits a short gel time due to its excellent curing reactivity. Specifically, the gel time refers to the gel time of a homogeneous composition obtained by adding 0.6 g of dicumyl peroxide as a curing agent to 30 g of bismaleimide and stirring at 180°C, using a value measured according to JIS K6910. The gel time of the bismaleimide of the present invention is typically 300 seconds or less, preferably 280 seconds or less, more preferably 220 seconds or less, and even more preferably 180 seconds or less. There is no particular limitation on the lower limit of the gel time of the bismaleimide of the present invention; the gel time is typically 50 seconds or more (particularly 100 seconds or more).

[0054] The bismaleimide of the present invention can be co-located with epoxy resins, phenolic resins, compounds containing unsaturated bonds, and benzo[a]benzene[b]. It can be used as a resin composition, including aziridine compounds, polyimide resins, and polyamide-imide resins. The amount of these compounds can be determined according to the intended use and is not particularly limited, for example, it can be in the range of 5 to 50 parts by weight per 100 parts by weight of the resin composition.

[0055] Examples of epoxy resins include bisphenol A type epoxy resin, bisphenol E type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, polyoxynaphthylene type epoxy resin, bisphenol A phenolic varnish type epoxy resin, biphenyl type epoxy resin, phenolic varnish type epoxy resin, cresol phenolic varnish type epoxy resin, xylene phenolic varnish type epoxy resin, polyfunctional phenol type epoxy resin, naphthalene type epoxy resin, naphthalene skeleton modified phenolic varnish type epoxy resin, naphthylene ether type epoxy resin, phenol aralkyl type epoxy resin, anthracene type epoxy resin, and trifunctional phenol type epoxy resin. Resins, including 4-functional phenolic epoxy resins, triglycidyl isocyanurate, glycidyl ester epoxy resins, alicyclic epoxy resins, dicyclopentadiene phenolic varnish epoxy resins, biphenyl phenolic varnish epoxy resins, phenol aralkyl phenolic varnish epoxy resins, naphthol aralkyl phenolic varnish epoxy resins, aralkyl phenolic varnish epoxy resins, biphenyl aralkyl epoxy resins, naphthol aralkyl epoxy resins, dicyclopentadiene epoxy resins, polyol epoxy resins, phosphorus-containing epoxy resins, glycidylamines, and compounds containing double bonds of butadiene, etc.

[0056] Examples of phenolic resins include bisphenol A type phenolic resin, bisphenol E type phenolic resin, bisphenol F type phenolic resin, bisphenol S type phenolic resin, phenolic varnish resin, bisphenol A phenolic varnish type phenolic resin, glycidyl ester type phenolic resin, aralkyl phenolic varnish type phenolic resin, biphenyl aralkyl type phenolic resin, cresol phenolic varnish type phenolic resin, polyfunctional phenolic resin, naphthol resin, naphthol phenolic varnish resin, polyfunctional naphthol resin, anthracene type phenolic resin, naphthalene skeleton modified phenolic varnish type phenolic resin, phenol aralkyl type phenolic resin, naphthol aralkyl type phenolic resin, dicyclopentadiene type phenolic resin, biphenyl type phenolic resin, alicyclic phenolic resin, polyol type phenolic resin, phosphorus-containing phenolic resin, and hydroxyl-containing organosilicon resins.

[0057] Examples of compounds containing unsaturated bonds include vinyl compounds such as ethylene, propylene, styrene, divinylbenzene, and divinylbiphenyl; monohydric or polyhydric alcohols such as methyl methacrylate, hydroxyethyl 2-methacrylate, hydroxypropyl 2-methacrylate, polypropylene glycol dimethacrylate, trimethylolpropane dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, and dipentaerythritol hexamethacrylate; and epoxy methacrylates such as bisphenol A epoxy methacrylate and bisphenol F epoxy methacrylate.

[0058] As benzo Azine compounds, for example, include 6,6-(1-methylethylidene)bis(3,4-dihydro-3-phenyl-2H-1,3-benzoxylene). 6,6-(1-methylethylidene)bis(3,4-dihydro-3-methyl-2H-1,3-benzoxazine), 6,6-(1-methylethylidene)bis(3,4-dihydro-3-methyl-2H-1,3-benzoxazine) (e.g., benzo[a]azine), etc. Additionally, as commercially available products, for example, "benzo[a]azine" manufactured by Shikoku Chemical Industry Co., Ltd. "Zinc F-a type", "Benzo" Examples include "P-d type" of aziridine and "RLV-100" manufactured by AIR·WATER.

[0059] In addition to being used in the core substrate or cover film of FPC, copper-clad laminate, passivation film, protective film, and interlayer insulating film on the surface of semiconductor elements of semiconductor devices, the resin composition of the present invention can also be used in a wide range of applications such as conformal coating of printed circuit boards, surface protective film of solar cells, alignment film of liquid crystal surface elements, protective film of glass fiber, printing paste composition, and conductive paste composition.

[0060] Example

[0061] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the present invention is not limited to these embodiments.

[0062] <Acid Value>

[0063] The determination was performed using a neutralization titration method according to JIS K0070 (1992). Approximately 1.0 g of bismaleimide was accurately weighed, and the concentration of bismaleimide was diluted to approximately 2% by mass using THF. Bromothymol blue (BTB) was used as an indicator, and titration was performed using potassium hydroxide (KOH). The number of mg of KOH consumed in neutralization was converted to the value per 1 g of bismaleimide.

[0064] <Viscosity>

[0065] Rotational viscosity was measured using a TOKIMEC DVL-BII digital viscometer (Type B viscometer) in a constant temperature bath controlled at 25±0.2℃.

[0066] <Weight-average molecular weight (Mw)>

[0067] The determination was performed using GPC. The determination conditions are as follows.

[0068] Chromatographic columns: Showa Denko Corporation Shodex® GPC KF-803 × 1 column, GPC KF-804 × 2 columns (3 columns in series)

[0069] Elution buffer: THF

[0070] Temperature: 40℃

[0071] Flow rate: 1.0 mL / min

[0072] Detector: UV detector

[0073] <Mix and compatibility>

[0074] At room temperature, 5g of 2,2-bis(4-glycidoxyphenyl)propane, which is a common epoxy resin prepolymer, is placed into a 20ml glass sample tube, and 5g of bismaleimide is added. The mixture is shaken by hand or stirred with a magnetic stirrer as needed until it reaches a state of no separation, turbidity, or bubbles (uniform state).

[0075] ○: It immediately becomes uniform by shaking it by hand.

[0076] △: Use a mixer to stir until it becomes uniform within 5 minutes.

[0077] ×: Even after stirring with a mixer for 10 minutes, it still did not become uniform.

[0078] <Gel Time>

[0079] As an indicator of curing reactivity, the gel time is determined according to the following steps.

[0080] 0.6 g of dicumyl peroxide as a curing agent was added to 30 g of bismaleimide and stirred to obtain a homogeneous composition. The gel time of the composition at 180 °C was determined according to JIS K6910.

[0081] Specifically, 0.5g of the composition was dropped onto a hot plate at 180°C, and a stopwatch was started. The composition was stirred with a spatula until the viscosity increased. The endpoint was defined as the moment when the spatula could no longer produce threads when pulled upwards, and the measurement time was recorded as the gel time.

[0082] Compositions with a gel time of less than 300 seconds are considered acceptable.

[0083] <Example 1>

[0084] 1) Preparation of crude bismaleimide solution

[0085] Under a nitrogen atmosphere, a mixed solvent consisting of toluene and NMP (mass ratio: toluene / NMP = 80 / 20), a dimerizing diamine (Croda Japan Co., Ltd. "PRIAMINE 1074", molecular weight: 547): 0.17 mol, maleic anhydride: 0.34 mol, p-toluenesulfonic acid as the first acid catalyst: 0.15 mol, and maleic anhydride as the second acid catalyst: 0.22 mol were added to a glass reaction vessel equipped with a reflux cooler with a water separator, a stirrer, and a thermometer, and the mixture was stirred. The resulting solution was heated to reflux while stirring. Water generated during the reaction was separated by azeotropic reaction, and the mixture was refluxed at approximately 125°C for 6 hours. After cooling, a two-phase orange-yellow solution was obtained. The upper phase of the obtained solution was then removed and washed twice with an aqueous solvent to obtain a crude bismaleimide solution with a solid content of 30% by mass using toluene as the solvent. The crude bismaleimide has an acid value of 8.2 mg-KOH / g.

[0086] 2) Use CDI to reduce acid value

[0087] Under a nitrogen atmosphere, the above-mentioned crude bismaleimide solution (200 g), N,N′-diisopropylcarbodiimide (DIC) (1.2 g equivalent to 1.05 times the acid value of the crude bismaleimide), and methanol were added to a glass reaction vessel equipped with a stirrer and a thermometer. The mixture was heated at 60°C for 60 minutes and then cooled to obtain an orange-yellow solution. The solution was purified by washing twice with a water-based solvent, and the solvent was distilled off to obtain bismaleimide (A-1). This bismaleimide had an acid value of 0.97 mg-KOH / g and a viscosity of 2.5 Pa·s. The bismaleimide was measured under the above conditions. 1 H-NMR, the results are shown in Figure 1 .like Figure 1 As shown, using this 1 The integral value (A) of peak 1 (δ: approximately 3.5 ppm multiplet) and the integral value (B) of peak 2 (δ: approximately 6.7 ppm singlet) in the H-NMR spectrum were compared, and the result was B / A = 0.86.

[0088] <Example 2>

[0089] The second acid catalyst was set to maleic acid: 0.12 mol, and the amount of DIC was set to 1.9 g (1.05 equivalents relative to the acid value of crude bismaleimide). Otherwise, the same procedure as in Example 1 was followed to obtain bismaleimide (A-2).

[0090] <Example 3>

[0091] The first acid catalyst was set as methanesulfonic acid: 0.31 mol, the second acid catalyst was set as maleic anhydride: 0.32 mol, and the amount of DIC was set as 0.6 g (1.1 equivalents relative to the acid value of crude bismaleimide). Otherwise, the same procedure as in Example 1 was followed to obtain bismaleimide (A-3).

[0092] <Example 4>

[0093] The first acid catalyst was set as methanesulfonic acid: 0.31 mol, the second acid catalyst was set as maleic acid: 0.26 mol, and the DIC amount was set as 1.1 g (1.0 equivalent relative to the acid value of crude bismaleimide). Otherwise, the same procedure as in Example 1 was followed to obtain bismaleimide (A-4).

[0094] <Example 5>

[0095] The first acid catalyst was set as methanesulfonic acid: 0.39 mol, the second acid catalyst was set as maleic anhydride: 0.49 mol, and the DIC amount was set as 1.2 g (1.03 equivalents relative to the acid value of crude bismaleimide). Otherwise, the same procedure as in Example 1 was followed to obtain bismaleimide (A-5).

[0096] <Comparative Example 1>

[0097] The first acid catalyst was set to methanesulfonic acid: 0.31 mol, no second acid catalyst was used, and the amount of DIC was set to 2.3 g (1.1 equivalents relative to the acid value of crude bismaleimide). Otherwise, the same procedure as in Example 1 was followed to obtain bismaleimide (B-1).

[0098] <Comparative Example 2>

[0099] Without using the first acid catalyst, the second acid catalyst was set to maleic anhydride of the second acid catalyst: 0.32 mol, and the amount of DIC was set to 3.0 g (1.1 equivalents relative to the acid value of crude bismaleimide). Otherwise, the same procedure as in Example 1 was followed to obtain bismaleimide (B-2).

[0100] <Comparative Example 3>

[0101] The first acid catalyst was set to methanesulfonic acid: 0.09 mol, the second acid catalyst was set to maleic anhydride: 0.10 mol, and the DIC amount was set to 2.2 g (1.1 equivalents relative to the acid value of crude bismaleimide). Except as described above, the same procedure as in Example 1 was followed to obtain bismaleimide (B-3).

[0102] <Comparative Example 4>

[0103] According to Patent Document 6 and Example 12, crude bismaleimide was obtained. Conversely, in the same manner as in Example 1, a CDI reaction was performed to obtain purified bismaleimide (B-4). Specifically, a solution of 0.058 mol Versamine 552 dissolved in 90 mL tetrahydrofuran (THF) was slowly added to a solution of 0.127 mol maleic anhydride dissolved in 60 mL THF. After 1 hour of addition, 125 mL acetic anhydride was added, and the reaction mixture was stirred for 24 hours. The reaction mixture was refluxed and maintained at the reflux temperature for 3 hours. 0.1 g benzoquinone was added to the reaction mixture, and the solvent was removed under vacuum. 75 mL THF and 1-hydroxybenzotriazole (HOBt) were added to the resulting residue, dissolved, and stirred at room temperature for 24 hours. Then, the solvent was removed at 30°C, and the residue was extracted twice with 500 mL pentane. The combined pentane fractions, when cooled in a dry ice / isopropanol bath, crystallize out a white solid. This solid is then concentrated by cold filtration to obtain a crude bismaleimide solution with a concentration of 50% by mass, using pentane as the solvent. The acid value of this crude bismaleimide is 9.8 mg-KOH / g. 1.5 g of DIC (1.1 equivalents relative to the acid value of the crude bismaleimide) is added to 120 g of the obtained crude bismaleimide solution, followed by methanol. The mixture is heated at 60°C for 60 minutes and then cooled to obtain an orange-yellow solution. This solution is purified by washing twice with an aqueous solvent, and the solvent is removed by distillation to obtain bismaleimide (B-4).

[0104] <Comparative Example 5>

[0105] According to Patent Document 6 and Example 13, crude bismaleimide was obtained. Conversely, CDI was reacted in the same manner as in Example 1 to obtain purified bismaleimide (B-5). Specifically, a solution of 0.096 mol Versamine 552 dissolved in 60 mL THF was slowly added to a solution of 0.206 mol maleic anhydride dissolved in 300 mL THF. After the addition was complete, the reaction mixture was stirred for one hour, and then HOBt was dissolved in it. The stirred reaction mixture was cooled in an ice bath, and then 0.238 mol DCC was added little by little. After this addition was complete, the reaction mixture was further stirred in an ice bath for one hour. Then, the ice bath was removed, and the stirred reaction mixture was allowed to warm to room temperature overnight. The reaction mixture was filtered, and the resulting solid was washed with THF. All of these THF fractions were combined, and 0.2 g of methoxyphenol was added. Then, the THF was removed at 30°C. The residue was extracted with hexane, and the hexane was removed. Next, by extracting again with pentane, a crude bismaleimide solution with a concentration of 50% by mass was obtained using pentane as a solvent. The acid value of this crude bismaleimide was 6.7 mg-KOH / g. 1.0 g of DIC (1.1 equivalents relative to the acid value of the crude bismaleimide) was added to 120 g of the obtained crude bismaleimide solution, followed by methanol. The mixture was heated at 60°C for 60 minutes and then cooled to obtain an orange-yellow solution. The solution was purified by washing twice with an aqueous solvent, and the solvent was distilled off to obtain bismaleimide (B-5).

[0106] <Comparative Example 6>

[0107] According to Patent Document 7, Synthesis Example 1, crude bismaleimide was obtained. Conversely, in the same manner as in Example 1, a CDI reaction was performed to obtain purified bismaleimide (B-6). Specifically, triethylamine (38.45 g, 0.380 mol) was added to toluene (200 mL), and methanesulfonic acid (37.44 g, 0.390 mol) was added dropwise while stirring. After stirring at room temperature for 30 minutes, maleic anhydride (25.90 g, 0.264 mol) was added, followed by Priamine 1074 (56.98 g, 0.104 mol). After stirring at room temperature for 30 minutes, the mixture was refluxed at 110°C for 8 hours to remove water from the system. The resulting reaction solution was washed with brine, filtered through silica gel, and the toluene was removed by vacuum distillation to obtain crude bismaleimide. The acid value of this crude bismaleimide was 26.0 mg-KOH / g. The crude bismaleimide was dissolved in toluene. 3.9 g of DIC (1.1 equivalents relative to the acid value of the crude bismaleimide) was added to 200 g of a 30% (w / w) bismaleimide solution. Methanol was then added, and the mixture was heated at 60°C for 60 minutes and then cooled to obtain an orange-yellow solution. The solution was purified by washing twice with an aqueous solvent, and the solvent was removed by distillation to obtain bismaleimide (B-6).

[0108] Table 1 shows the amount of acid catalyst used in the examples and comparative examples, the acid value of the crude bismaleimide, and the amount of CDI used. Table 2 shows the comparison of the acid value, viscosity, NMR content, molecular weight, cured product formulation, and evaluation results of the curing reactivity of the obtained bismaleimides.

[0109]

[0110]

[0111] As shown in the examples, the bismaleimide of the present invention, by using two specific catalysts in combination, not only reduces the acid value but also sufficiently reduces the viscosity. Furthermore, the high miscibility when combined with other agents indicates a significant improvement in workability. Moreover, compared to comparative examples, the gel time is significantly shortened, indicating a significant improvement in reactivity. In Comparative Example 1, which uses only an acid catalyst with a pKa less than 1, and Comparative Example 2, which uses only an acid catalyst with a pKa greater than 1, the viscosity is high, indicating poor miscibility. As shown in Comparative Example 3, even when using both an acid catalyst with a pKa less than 1 and an acid catalyst with a pKa greater than 1, the viscosity increases if the amount of catalyst is small. Furthermore, even in Comparative Examples 4 and 5 according to Patent Document 6, although the acid value is reduced, the viscosity is high, indicating poor miscibility. Additionally, the reactivity during curing is insufficient. As shown in Comparative Example 6, when using an acid catalyst and triethylamine, a basic compound, during the synthesis of crude bismaleimide, the acid catalyst is neutralized, thus the combined effect of the catalysts is not achieved, and the viscosity reduction is insufficient. In addition, the reactivity during curing is insufficient.

[0112] Industrial availability

[0113] The bismaleimide of the present invention has low viscosity and a sufficiently low acid value, thus exhibiting good miscibility and workability when combined with other agents such as curable resins. Furthermore, its reactivity during curing is significantly improved. Therefore, it is suitable for use as a component in sealing material compositions, adhesive compositions, etc., used in the manufacture of electronic components employing semiconductors, etc.

Claims

1. A bismaleimide, formed by maleimidation of the amino group of a dimer diamine, characterized in that: 1) The acid value of the bismaleimide is below 2 mg-KOH / g. 2) The viscosity of the bismaleimide, measured using a type B viscometer at 25°C, is below 3.0 Pa·s. 3) The weight-average molecular weight of the bismaleimide, as determined by GPC, is in the range of 1400 to 1800.

2. The bismaleimide according to claim 1, characterized in that, exist 1 In H-NMR, when comparing the integral value (A) of the peak corresponding to the proton of the methylene group directly bonded to the nitrogen atom of the maleimide group and the integral value (B) of the peak corresponding to the vinyl proton of the maleimide group, B / A exceeds 0.

80.

3. A method for manufacturing bismaleimide, which is the method for manufacturing bismaleimide according to claim 1 or 2, characterized in that, The following processes are included: 1) A process of preparing a crude bismaleimide solution with an acid value exceeding 2 mg-KOH / g by using an acid with a pKa less than 1 and an acid with a pKa greater than 1 as catalysts, and using the catalyst with a molar percentage of more than 115 mol% relative to the dimer diamine. 2) A process of making the acid value less than 2 mg-KOH / g by reacting the acid component in the solution with a carbodiimide compound (CDI).

4. A resin composition comprising: the bismaleimide as described in claim 1 or 2; and selected from epoxy resins, phenolic resins, compounds containing unsaturated bonds, benzo[a]benzene, and other similar compounds. At least one of aziridine compounds, polyimide resins, and polyamide-imide resins.

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