Polysilazane compound, polysilazane composition, and adhesive agent

Abstract

The present invention provides (A) a polysilazane compound that has structures represented by formulae (A-1), (A-2), and (A-3) and does not have a hydrosilyl group (in the formulae, each R is a group selected from among an aliphatic hydrocarbon group having 1 to 6 carbon atoms and a phenyl group, and the R groups may be the same as or different from each other in the polysilazane compound, provided that the ratio of the phenyl group to the total amount of the R groups is 0.3 or less). The polysilazane compound is characterized in that the ratio of each structural unit to the polysilazane compound satisfies all of formulae (1) to (3).　Formula (1): (A-1) + (A-2) + (A-3) = 1; formula (2): 0.2 ≤ (A-1) ≤ 0.7; and formula (3): 0 < (A-2) ≤ (A-3) × 4. Thus, provided is a material which has a high and tunable refractive index, has high heat resistance, and is capable of bonding members with sufficient strength.

Description

Polysilazane compound, polysilazane composition, and adhesive

[0001] The present invention relates to a polysilazane compound, a polysilazane composition, and an adhesive.

[0002] In recent years, with the development of LED technology, further improvement in the brightness and heat resistance of LED devices has been studied. Conventionally, the mainstream method for increasing brightness has been to arrange a plurality of LEDs side by side. However, for the purpose of miniaturization and weight reduction, a method aiming for high brightness with a single LED chip has been studied. In particular, high brightness is required for lighting and vehicle headlights. The color of an LED can be adjusted by an LED chip and a phosphor or quantum dot (QD) for wavelength conversion. The light generated from the LED chip is finally emitted into the atmosphere through various members. In order to increase the brightness, the refractive index of each member becomes very important. This is because when light passes through a member, light is refracted or diffracted due to the refractive index difference between the members. Although these physical phenomena also vary depending on the shape of the members and cannot be generally stated, generally, the smaller the refractive index difference between the members, the higher the light extraction efficiency. Specifically, higher brightness can be obtained when there is a sealing layer with an intermediate refractive index between the LED chip and the air rather than when light exits from the LED chip with a high refractive index into the air with a low refractive index.

[0003] A general methyl-based silicone resin has a refractive index of about 1.40 to 1.45. However, in order to obtain higher light extraction efficiency, a higher refractive index is required. Therefore, a phenyl-based silicone resin modified with a phenyl group having a higher refractive index than a methyl group may be used (Patent Document 1). However, when a phenyl group is introduced, the viscosity and the hardness after curing tend to increase, and there is a problem that it deteriorates and coloring occurs when exposed to high temperatures. Therefore, there is a limit to the amount that can be modified, and the refractive index can be guaranteed up to about 1.45 to 1.55 for reliable long-term use. There is also a method of dispersing a filler with a high refractive index in a silicone resin to increase the refractive index. However, it is difficult to maintain uniform dispersion and transparency, and there is a limit to the addition amount, so a significant improvement in the refractive index cannot be achieved (Patent Document 2).

[0004] Japanese Patent Publication No. 2019-528246 Japanese Unexamined Patent Application Publication No. 2021-155256

[0005] This invention has been made in view of the above circumstances, and aims to provide a material that has a high refractive index, allows for refractive index adjustment, has high heat resistance, and can bond components with sufficient strength.

[0006] To solve the above problems, the present invention provides (A) a polysilazane compound having a structure represented by the following formulas (A-1), (A-2), and (A-3), and having no hydrosilyl group, (In the formula, R is a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms or a phenyl group, and R may be the same or different in the polysilazane compound. However, the proportion of phenyl groups is 0.3 or less of the total R.) The present invention provides a polysilazane compound characterized in that the ratio of each structural unit to the polysilazane compound satisfies all of the following formulas (1) to (3): (A-1) + (A-2) + (A-3) = 1 …(1) 0.2 ≤ (A-1) ≤ 0.7 …(2) 0 < (A-2) ≤ (A-3) × 4 …(3)

[0007] The polysilazane compound of the present invention provides a material that has a high refractive index, allows for refractive index adjustment, has high heat resistance, and can bond components with sufficient strength.

[0008] Furthermore, it is preferable that the polysilazane compound has a methyl group as R in formula (A-1).

[0009] From the viewpoint of the stability and workability of the generated polymer, it is preferable that R in the above formula (A-1) is a methyl group.

[0010] Furthermore, it is preferable that the ratio of the structural unit represented by formula (A-1) in the polysilazane compound is within the range of 0.3 to 0.7.

[0011] If the ratio of structural units represented by the above formula (A-1) is within the above range, the hardness of the cured product will be high and the adhesive strength will be sufficient.

[0012] Furthermore, it is preferable that the ratio of the structural unit represented by formula (A-3) in the polysilazane compound is within the range of 0.1 to 0.7.

[0013] Furthermore, the refractive index of the polysilazane compound after curing at 25°C can be within the range of 1.50 to 1.65.

[0014] The cured product obtained from the polysilazane compound has a high refractive index and its refractive index can be adjusted.

[0015] Furthermore, the present invention can provide a polysilazane composition comprising the polysilazane compound described above and a solvent.

[0016] By including the above-mentioned solvent in the polysilazane composition, the viscosity of the polysilazane composition can be adjusted and its wettability to the substrate can be improved.

[0017] The polysilazane compound of the present invention can be used to make an adhesive containing the above-mentioned polysilazane compound.

[0018] The polysilazane compound of the present invention has a high refractive index after curing, is less prone to voids and cracks, and has excellent heat resistance, making it suitable for use as an adhesive.

[0019] The polysilazane composition of the present invention can be used to make an adhesive containing the above-mentioned polysilazane composition.

[0020] The polysilazane composition of the present invention is less prone to voids and cracks during curing and has excellent heat resistance, making it suitable for use as an adhesive.

[0021] As described above, the polysilazane compounds of the present invention have three types of structures and are specific polysilazane compounds that do not have a hydrosilyl group. With the polysilazane compounds and polysilazane compositions of the present invention, it is possible to obtain cured products with a high refractive index, adjustable refractive index, and high heat resistance. Furthermore, the above polysilazane compounds and polysilazane compositions have sufficiently high adhesive properties and can be suitably used as adhesives.

[0022] As mentioned above, there was a need to develop a material that had a high refractive index, whose refractive index could be adjusted, had high heat resistance, and could bond components with sufficient strength.

[0023] As a result of diligent research into the above-mentioned problems, the inventors have found that certain polysilazane compounds and certain polysilazane compositions can solve the above-mentioned problems, and have completed the present invention.

[0024] That is, the present invention relates to (A) a polysilazane compound having a structure represented by the following formulas (A-1), (A-2), and (A-3), and having no hydrosilyl group, (In the formula, R is a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms or a phenyl group, and R may be the same or different in the polysilazane compound. However, the proportion of phenyl groups is 0.3 or less of the total R.) The polysilazane compound is characterized in that the ratio of each structural unit to the polysilazane compound satisfies all of the following formulas (1) to (3): (A-1) + (A-2) + (A-3) = 1 …(1) 0.2 ≤ (A-1) ≤ 0.7 …(2) 0 < (A-2) ≤ (A-3) × 4 …(3)

[0025] The present invention will be described in detail below, but the present invention is not limited to these descriptions.

[0026] [Polysilazane Compounds] The polysilazane compounds of the present invention are (A) polysilazane compounds having the structure represented by the following formulas (A-1), (A-2), and (A-3), and having no hydrosilyl group, (In the formula, R is a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms or a phenyl group, and R may be the same or different in the polysilazane compound. However, the proportion of phenyl groups is 0.3 or less of the total R.) The polysilazane compound is characterized in that the ratio of each structural unit to the polysilazane compound satisfies all of the following formulas (1) to (3): (A-1) + (A-2) + (A-3) = 1 …(1) 0.2 ≤ (A-1) ≤ 0.7 …(2) 0 < (A-2) ≤ (A-3) × 4 …(3)

[0027] The different structures of the polysilazane compound of the present invention, designated as (A-1), (A-2), and (A-3), are described below.

[0028] (A-1) Structure (In the formula, R is a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms or a phenyl group, and R may be the same or different in the polysilazane compound. However, the proportion of phenyl groups is 0.3 or less of the total R.)

[0029] The polysilazane structure (A-1) is the structure described above. In the formula, R is a group selected from aliphatic hydrocarbon groups or phenyl groups having 1 to 6 carbon atoms, such as methyl, ethyl, vinyl, and phenyl groups, and these may be the same or different in the polysilazane compound. However, the proportion of phenyl groups is 0.3 or less of the total R, and preferably 0 to 0.2. Among these, from the viewpoint of the stability and workability of the resulting polymer, it is more preferable that R is a methyl group, and even more preferable that R is all methyl groups. The ratio of the above (A-1) structural units must be within the range of 0.2 to 0.7 of the total polysilazane compound. If it is less than 0.2, the viscosity of the polysilazane compound will increase, impairing workability. If it exceeds 0.7, sufficient hardness will not be obtained in the cured product, and the adhesive strength will be insufficient. The preferred range for the ratio of (A-1) is 0.3 to 0.7, and more preferably 0.4 to 0.5.

[0030] (A-2) Structure

[0031] The polysilazane structure (A-2) is the structure described above. The ratio of structural units of (A-2) above must be greater than 0 and equal to or less than four times the ratio of structural units of (A-3) described below. Since the structural units of (A-2) contain T units of Si, the crosslinking density increases easily during curing, which has the effect of increasing adhesive strength. On the other hand, it contributes little to improving the refractive index, so if there is too much of it, the refractive index cannot be increased. Therefore, the ratio of structural units of (A-2) and (A-3) is important for adjusting the adhesive strength and refractive index. The preferred range for the ratio of structural units of (A-2) above is within the range of 0.01 to 0.4. More preferably, it is within the range of 0.05 to 0.3. Within this range, the viscosity is not too high and sufficient adhesive strength is achieved, so it is preferable.

[0032] (A-3) Structure

[0033] The polysilazane structure (A-3) is the structure described above. The ratio of structural units in (A-3) must be the same as, or greater than, 1 / 4 the ratio of structural units in (A-2) described above. (A-3) has the effect of increasing the refractive index due to the inclusion of phenyl groups. Basically, increasing the ratio of structural units in (A-3) increases the refractive index of the polysilazane compound, so it is possible to adjust the refractive index by changing the ratio with the structural units in (A-2) described above. The preferred range for the ratio of structural units in (A-3) is 0.1 to 0.7. More preferably, it is within the range of 0.15 to 0.5.

[0034] Furthermore, the polysilazane compound of the present invention satisfies all of the following formulas (1) to (3) in terms of the amounts of the structural units of formulas (A-1), (A-2), and (A-3): (A-1) + (A-2) + (A-3) = 1 …(1) 0.2 ≤ (A-1) ≤ 0.7 …(2) 0 < (A-2) ≤ (A-3) × 4 …(3)

[0035] If the values ​​fall outside the range that satisfies these equations, the high refractive index cannot be maintained, resulting in an imbalance in viscosity, adhesive strength, and other factors, and impairing workability.

[0036] The ratios of the structural units (A-1), (A-2), and (A-3) above are as follows: １ H-NMR and ２９ This can be determined by Si-NMR.

[0037] Furthermore, while the molecular weight of the polysilazane compound of the present invention is not particularly limited, it is preferable that the weight-average molecular weight be in the range of 500 to 10,000 from the viewpoint of workability such as curing speed and viscosity. A weight-average molecular weight of 500 or more is preferable because curing proceeds quickly, and a weight-average molecular weight of 10,000 or less is preferable because the viscosity is easy to handle and there is no risk of curing during use. The weight-average molecular weight was measured using a GPC apparatus with polystyrene as the standard substance in the following manner.

[0038] [Measurement Conditions] Developing solvent: Tetrahydrofuran (THF) Flow rate: 0.6 mL / min Detector: UV detector Column: TSK Guardcolumn SuperH-L TSKgel SuperMultipore HZ-M (4.6 mm I.D. × 15 cm × 4) (All manufactured by Tosoh Corporation) Column temperature: 40°C Sample injection volume: 20 μL (THF solution with a concentration of 0.5 wt%)

[0039] In the present invention, in order to obtain high refractive index characteristics, a polysilazane compound is used instead of the conventionally used silicone resin. This is related to the difference in the behavior during curing between the silicone resin and the polysilazane compound. In the case of a silicone resin, when it contains a large amount of phenyl groups, the solvent solubility is poor due to the influence of steric hindrance and the viscosity also increases, making coating difficult. Although the solvent solubility and viscosity can be improved by making the molecular weight as small as possible, in the case of an addition polymerization type, the number of carbon-carbon bonds as bonding groups for curing increases, resulting in a decrease in heat resistance. In addition, in the case of a condensation curing type, although carbon-carbon bonds are not included, the amount of desorbed components during condensation increases, so when used in applications where members such as adhesives are sandwiched, voids are likely to occur.

[0040] On the other hand, while polysilazane compounds exhibit increased viscosity when they contain a large amount of phenyl groups, similar to silicone resins, they can be used with virtually no problems even when the molecular weight is reduced. This is because, during the curing reaction of polysilazane, nitrogen atoms in the structure are replaced by oxygen atoms by oxygen gas and moisture in the atmosphere, causing crosslinking. At this time, the amount of oxygen gas that penetrates into the polysilazane compound and the amount of ammonia gas released by the curing reaction are almost the same, so voids due to rapid gas generation do not occur. However, if the structure of the polysilazane compound contains hydrosilyl groups, desorption gas is generated regardless of the amount of oxygen gas that penetrates, resulting in voids and making it unusable. Therefore, it is important that the polysilazane compounds of the present invention are composed of the structures (A-1), (A-2), and (A-3) described above, and that the main chain in the structure does not contain carbon-carbon bonds or hydrosilyl groups. They are composed only of the structures (A-1), (A-2), and (A-3), and do not contain any structures other than those described above (A-1) to (A-3).

[0041] [Refractive Index] The polysilazane compound of the present invention may have a refractive index in the range of 1.50 to 1.65 at 25°C after curing. The refractive index is the value obtained when measuring the refractive index at a wavelength of 633 nm at 25°C using a micro-spectroscopic film thickness meter (Otsuka Electronics Co., Ltd., OPTM) for a coating film with a thickness of 1 μm.

[0042] <Polysilazane composition> In the present invention, a polysilazane composition can be provided which comprises the polysilazane compound described above and a solvent.

[0043] [Solvent] The polysilazane composition of the present invention may contain a solvent to improve workability during coating. Examples of diluent solvents include alkane compounds such as n-hexane, n-octane, and n-nonane; alkene compounds such as 1-octene, 1-nonene, and 1-decene; cycloalkane compounds such as cyclohexane, methylcyclohexane, and dimethylcyclohexane; ester compounds such as n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, isoamyl acetate, and ethyl caproate; and ether compounds such as diethyl ether, dibutyl ether, and ethylene glycol diethyl ether.

[0044] The diluent can be considered to be used for adjusting the viscosity of the above polysilazane composition and improving the wettability to the substrate. However, when the total polysilazane composition is 100% by mass, it is preferable that the non-volatile content exceeds 50% by mass. If the amount of the diluent is 50% by mass or less, it is preferable because the diluent hardly remains in the cured product.

[0045] [Curing Catalyst] A curing catalyst may be added to the polysilazane composition of the present invention as necessary. The curing catalyst is not particularly limited as long as the polymerization of the polysilazane compound used proceeds, but it is preferably a catalyst that can be uniformly dispersed in order not to impair transparency. Examples of specific curing catalysts include carboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, linolenic acid, linoleic acid, oleic acid, and oxalic acid, hydroxycarboxylic acids such as malic acid and citric acid, and organic acids, titanium, manganese, cobalt, nickel, zinc, and other d-block elements belonging to the fourth period of the periodic table, ruthenium, rhodium, palladium, osmium, iridium, platinum, and other platinum group elements, aluminum, tin, zinc, and other amphoteric elements, and the like, and metal compounds having these metal elements. Among them, organic aluminum compounds and organic zirconium compounds are particularly preferable because the curing reaction proceeds with a small amount of addition, they are soluble in solvents, and there is no coloring.

[0046] The mixing ratio with the polysilazane compound varies depending on the composition of the polysilazane compound and the type of curing catalyst added. In the case of an organic aluminum compound, it is preferably within the range of 0.01 to 5 parts by mass with respect to 100 parts by mass of the polysilazane composition. Within this range, the balance between the curing rate and workability is excellent when used as an adhesive.

[0047] [Other Additives] In addition to curing catalysts and solvents, the polysilazane composition of the present invention may also contain additives such as fillers. Examples of fillers include, for example, homogeneous or heterogeneous metal fillers containing metallic elements such as magnesium, aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, zinc, gallium, zirconium, niobium, palladium, and platinum; reinforcing inorganic fillers such as fumed silica, fumed titanium dioxide, and fumed alumina; and non-reinforcing inorganic fillers such as fused silica, alumina, zirconium oxide, calcium carbonate, calcium silicate, titanium dioxide, ferric oxide, and zinc oxide.

[0048] The above-mentioned fillers may be added to further improve the refractive index of the composition, but care must be taken regarding transparency and dispersibility. Other additives include organosiloxane oligomers containing functional groups selected from alkenyl groups, alkoxysilyl groups, and epoxy groups, adhesive aids such as organooxysilyl-modified isocyanurate compounds and their hydrolysis condensates, and silicone oils such as dimethyl silicone and phenyl silicone, which can be added in any proportion depending on the required properties.

[0049] Methods for applying the polysilazane compound or polysilazane composition of the present invention include, for example, roll coating methods such as chamber doctor coaters, single-roll kiss coaters, reverse kiss coaters, bar coaters, reverse roll coaters, forward-rotating roll coaters, blade coaters, and knife coaters, as well as spin coating methods, dispensing methods, dipping methods, spraying methods, transfer methods, and slit coating methods.

[0050] There are no particular restrictions on the substrate to be coated, but examples include organic synthetic resins such as polyethylene (PE), polyvinyl chloride (PVC), polystyrene (PS), polyvinyl acetate (PVAc), polyurethane (PUR), acrylonitrile butadiene styrene resin (ABS), acrylic resin (PMMA), polyamide (PA), nylon, polycarbonate (PC), polyethylene terephthalate (PET), polyimide (PI), and bismaleimide resin (BMI); silicone resins such as methyl silicone and phenyl silicone; metals such as aluminum, silicon, iron, nickel, copper, silver, and gold; oxides such as alumina, silica, titanium dioxide, and zinc oxide; and nitrides such as boron nitride, aluminum nitride, silicon nitride, and gallium nitride. Optical materials whose performance is improved by increasing the refractive index are particularly preferred.

[0051] The thickness of the coating film varies depending on the difference in coefficient of thermal expansion with the substrate and the exposure temperature, but generally, the cured film thickness is preferably 0.1 to 100 μm, and more preferably 0.5 to 50 μm.

[0052] It is preferable to apply the uncured polysilazane compound or polysilazane composition to one or both of the components to form a coating film, and then heat and dry the coating film. This step is intended to completely remove solvents and low-molecular-weight components contained in the coating film, but it is not necessarily required if no solvents are present.

[0053] The processing temperature for the heating and drying process is typically in the range of 25°C to 200°C, preferably 70°C to 150°C. Preferred processing methods for the heating and drying process include heat treatment, microwave treatment, and infrared treatment. When used as an adhesive, after the heating and drying process, the parts to be bonded are pressed together to prevent air bubbles from forming and allowed to cure. Curing proceeds sufficiently even at room temperature, but heating can accelerate the curing process even further.

[0054] [Adhesives] The polysilazane compounds and polysilazane compositions of the present invention are less prone to voids and cracks during curing and have excellent heat resistance, making them suitable for use as adhesives.

[0055] The present invention will be specifically described below using synthesis examples, embodiments, and comparative examples, but the present invention is not limited to these. In the following examples, "parts" refers to parts by mass.

[0056] [Synthesis Example A] 4,000 g of pyridine was mixed with 326 g of dimethyldichlorosilane, 302 g of methyltrichlorosilane, and 107 g of phenyltrichlorosilane as starting materials. Ammonia gas was blown into the reaction mixture at a rate of 1.0 L / min for 425 minutes to react these silanes. At this time, a white ammonium chloride salt was formed, which was removed by filtration. The filtrate was heated at 100°C under a reduced pressure of approximately 800 Pa to remove the pyridine by distillation to obtain polysilazane compound A. The ratios of (A-1), (A-2), and (A-3) in the obtained compound were... １ H-NMR and ２９ The results were obtained by Si-NMR and are shown in Table 1 below.

[0057] [Synthesis Example B] 4,000 g of pyridine was mixed with 326 g of dimethyldichlorosilane, 265 g of methyltrichlorosilane, and 160 g of phenyltrichlorosilane as starting materials. Ammonia gas was blown into the reaction mixture at a rate of 1.0 L / min for 425 minutes to allow these silanes to react. Subsequently, the same procedure as in Synthesis Example A was carried out to obtain polysilazane compound B. The ratios of (A-1), (A-2), and (A-3) in the obtained compound are shown in Table 1 below.

[0058] [Synthesis Example C] 4,000 g of pyridine was mixed with 326 g of dimethyldichlorosilane, 76 g of methyltrichlorosilane, and 428 g of phenyltrichlorosilane as starting materials. Ammonia gas was blown into the reaction mixture at a rate of 1.0 L / min for 425 minutes to allow these silanes to react. Subsequently, the same procedure as in Synthesis Example A was carried out to obtain polysilazane compound C. The ratios of (A-1), (A-2), and (A-3) in the obtained compound are shown in Table 1 below.

[0059] [Synthesis Example D] 4,000 g of pyridine was mixed with 196 g of dimethyldichlorosilane, 416 g of methyltrichlorosilane, and 160 g of phenyltrichlorosilane as starting materials. Ammonia gas was blown into the reaction mixture at a rate of 1.0 L / min for 459 minutes to react these silanes. Subsequently, the same procedure as in Synthesis Example A was carried out to obtain polysilazane compound D. The ratios of (A-1), (A-2), and (A-3) in the obtained compound are shown in Table 1 below.

[0060] [Synthesis Example E] 4,000 g of pyridine was mixed with 457 g of dimethyldichlorosilane, 113 g of methyltrichlorosilane, and 160 g of phenyltrichlorosilane as starting materials. Ammonia gas was blown into the reaction mixture at a rate of 1.0 L / min for 391 minutes to react these silanes. Subsequently, the same procedure as in Synthesis Example A was carried out to obtain polysilazane compound E. The ratios of (A-1), (A-2), and (A-3) in the obtained compound are shown in Table 1 below.

[0061] [Synthesis Example F] 4,000 g of pyridine was mixed with 163 g of dimethyldichlorosilane, 241 g of methylphenyldichlorosilane, 302 g of methyltrichlorosilane, and 107 g of phenyltrichlorosilane as starting materials. Ammonia gas was blown into the reaction mixture at a rate of 1.0 L / min for 425 minutes to allow these silanes to react. Subsequently, the same procedure as in Synthesis Example A was carried out to obtain polysilazane compound F. The ratios of (A-1), (A-2), and (A-3) in the obtained compound are shown in Table 1 below.

[0062] [Synthesis Example G] 4,000 g of pyridine was mixed with 291 g of monomethyldichlorosilane, 265 g of methyltrichlorosilane, and 160 g of phenyltrichlorosilane as starting materials. Ammonia gas was blown into the reaction mixture at a rate of 1.0 L / min for 425 minutes to react these silanes. Subsequently, the same procedure as in Synthesis Example A was carried out to obtain polysilazane compound G. The ratios of (A-1), (A-2), and (A-3) in the obtained compound are shown in Table 1 below.

[0063] [Synthesis Example H] 4,000 g of pyridine was mixed with 326 g of dimethyldichlorosilane and 378 g of methyltrichlorosilane as starting materials. Ammonia gas was blown into the reaction mixture at a rate of 1.0 L / min for 425 minutes to react these silanes. Subsequently, the same procedure as in Synthesis Example A was carried out to obtain polysilazane compound H. The ratios of (A-1), (A-2), and (A-3) in the obtained compound are shown in Table 1 below.

[0064] [Synthesis Example I] 4,000 g of pyridine was mixed with 98 g of dimethyldichlorosilane, 491 g of methyltrichlorosilane, and 214 g of phenyltrichlorosilane as halogenated silane starting materials. Ammonia gas was blown into the reaction mixture at a rate of 1.0 L / min for 485 minutes to allow these silanes to react. Subsequently, the same procedure as in Synthesis Example A was carried out to obtain polysilazane compound I. The ratios of (A-1), (A-2), and (A-3) in the obtained compound are shown in Table 1 below.

[0065] [Synthesis Example J] 4,000 g of pyridine was mixed with 555 g of dimethyldichlorosilane, 4 g of methyltrichlorosilane, and 11 g of phenyltrichlorosilane as halogenated silane starting materials. Ammonia gas was blown into the reaction mixture at a rate of 1.0 L / min for 297 minutes to allow these silanes to react. Subsequently, the same procedure as in Synthesis Example A was carried out to obtain polysilazane compound J. The ratios of (A-1), (A-2), and (A-3) in the obtained compound are shown in Table 1 below.

[0066] [Synthesis Example K] 4,000 g of pyridine was mixed with 326 g of dimethyldichlorosilane, 340 g of methyltrichlorosilane, and 53 g of phenyltrichlorosilane as halogenated silane starting materials. Ammonia gas was blown into the reaction mixture at a rate of 1.0 L / min for 425 minutes to allow these silanes to react. Subsequently, the same procedure as in Synthesis Example A was carried out to obtain polysilazane compound K. The ratios of (A-1), (A-2), and (A-3) in the obtained compound are shown in Table 1 below.

[0067] [Examples 1] to [Examples 5], [Example 9], and [Comparative Example 1] to [Comparative Example 5] 70 parts of the polysilazane compounds obtained in the above synthesis examples A to K and 30 parts of dibutyl ether were mixed in a vacuum degassing mixer at 25°C for 5 minutes to obtain polysilazane compositions A to K. Compositions A to K were applied to a 1 mm thick alumina plate and heated at 100°C for 10 minutes to dry. Then, a 0.5 mm thick glass plate was pressed on top, taking care not to introduce air bubbles, and heated at 150°C for 24 hours to prepare adhesive test specimens. Separately, these polysilazane compositions A to K were applied to 0.5 mm thick glass plates to thicknesses of 1 μm and 0.5 mm, respectively, heated at 100°C for 10 minutes to dry, and then heat-cured at 150°C for 24 hours to prepare test specimens. Then, adhesion, refractive index measurement of the coating film, and heat resistance tests were performed using the following methods. The results are shown in Table 2 below.

[0068] [Example 6] 70 parts of the polysilazane compound obtained in Synthesis Example B, 30 parts of dibutyl ether, and 0.07 parts of (2-oxo-5-oxa-3-hepten-4-yloxy)aluminum (Kelope EB-2: Hope Pharmaceutical Co., Ltd.) as a curing catalyst were mixed in a vacuum degassing mixer for 5 minutes to obtain polysilazane composition B-1. Subsequently, test specimens were prepared using the same procedure as above, and adhesion, refractive index measurement of the coating film, and heat resistance tests were performed. The results are shown in Table 2 below.

[0069] [Example 7] 70 parts of the polysilazane compound obtained in Synthesis Example B were used as polysilazane composition B-2. Subsequently, test specimens were prepared using the same procedure as above, and adhesion, refractive index measurement of the coating film, and heat resistance tests were performed. The results are shown in Table 2 below.

[0070] [Example 8] 70 parts of the polysilazane compound obtained in Synthesis Example B and 30 parts of n-nonane were mixed in a vacuum degassing mixer at 25°C for 5 minutes to obtain polysilazane composition B-3. Subsequently, test specimens were prepared using the same procedure as above, and adhesion, refractive index measurement of the coating film, and heat resistance tests were performed. The results are shown in Table 2 below.

[0071] [Comparative Example 6] 70 parts of an addition-curing silicone resin containing an equivalent amount of phenyl groups as the polysilazane compound obtained in Synthesis Example C (30% of the total amount of substituents), 30 parts of toluene, and 0.01 parts of a 1,3-diethynyl-1,1,3,3-tetramethyldisiloxane platinum complex as a curing catalyst were mixed in a vacuum degassing mixer for 5 minutes to obtain silicone composition C'. Subsequently, test specimens were prepared using the same procedure as above, and adhesion, refractive index measurement of the coating film, and heat resistance tests were performed. The results are shown in Table 2 below.

[0072] [Evaluation Method] Each test was performed using the test specimens prepared in the examples and comparative examples. The test methods are as follows.

[0073] [Adhesion Test] The adhesion test was performed on the adhesive test specimens prepared using the method described above. First, the specimens were visually inspected for defects such as cracks. Then, for specimens without defects, the alumina plate and glass plate, which were the base materials, were measured according to the method of JIS K 6850:1999, and the specimens were judged to have "good adhesion" if the base material fractured before the adhesive peeled off.

[0074] [Refractive Index Measurement] The refractive index of the coating film was measured at a wavelength of 633 nm at 25°C using a micro-spectrometer (OPTM, Otsuka Electronics Co., Ltd.). A coating film with a thickness of 1 μm was used for the measurement.

[0075] [Heat Resistance Test] In the heat resistance test, the change in total light transmittance after 100 hours at 250°C in a convection oven was measured, with the total light transmittance before the test set to 100%. The measurement was performed using a haze meter (Nippon Denshoku Industries Co., Ltd., NDH4000) in accordance with JIS K 7361-1:1997. A coating film with a thickness of 0.5 mm was used for the measurement.

[0076]

[0077]

[0078] As shown in Table 2 above, the refractive index of the cured coating film in Examples 1 to 9 using the polysilazane compound of the present invention was 1.50 or higher in all cases. Furthermore, the results of the adhesion test were also good.

[0079] On the other hand, in Comparative Example 1, which contained a hydrosilyl group in the polysilazane compound, hydrogen gas was generated during the adhesion test, resulting in voids. In Comparative Example 2, which contained no phenyl group at all, and Comparative Example 5, which contained only a small amount of phenyl group, the refractive index was low. Furthermore, in Comparative Examples 3 and 4, where the structural ratios of (A-1), (A-2), and (A-3) were outside the range of the present invention, the hardness became too high during the adhesion test, resulting in cracks, or the adhesive strength of the cured resin was insufficient.

[0080] In the heat resistance test, Examples 1 to 9 all maintained high total light transmittance compared to the initial values ​​before the test. On the other hand, Comparative Example 6, a silicone resin containing the same amount of phenyl groups as Example 3, showed a significant decrease in total light transmittance.

[0081] These findings indicate that the high refractive index compound of the present invention allows for adjustment of the refractive index, achieving a refractive index exceeding 1.50. Furthermore, it can be said that it is less prone to voids and cracks when used as a coating agent or adhesive, and exhibits excellent heat resistance.

[0082] This specification includes the following embodiments: [1]: (A) A polysilazane compound having a structure represented by the following formulas (A-1), (A-2), and (A-3), and having no hydrosilyl group, (In the formula, R is a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms or a phenyl group, and R may be the same or different in the polysilazane compound. However, the proportion of phenyl groups is 0.3 or less of the total R.) A polysilazane compound characterized in that the ratio of each structural unit to the polysilazane compound satisfies all of the following formulas (1) to (3): (A-1) + (A-2) + (A-3) = 1 …(1) 0.2 ≤ (A-1) ≤ 0.7 …(2) 0 < (A-2) ≤ (A-3) × 4 …(3) [2]: The polysilazane compound according to [1], characterized in that R in formula (A-1) is a methyl group. [3]: The polysilazane compound according to [1] or [2], characterized in that the ratio of the structural unit represented by formula (A-1) in the polysilazane compound is in the range of 0.3 to 0.7. [4]: The polysilazane compound according to [1], characterized in that the ratio of structural units represented by formula (A-3) in the polysilazane compound is in the range of 0.1 to 0.7. [5]: The polysilazane compound according to any one of [1] to [4], characterized in that the refractive index of the polysilazane compound at 25°C after curing is in the range of 1.50 to 1.65. [6]: A polysilazane composition characterized by comprising the polysilazane compound according to any one of [1] to [5] and a solvent. [7]: An adhesive characterized by comprising the polysilazane compound according to any one of [1] to [5]. [8]: An adhesive characterized by comprising the polysilazane composition according to [6].

[0083] It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention.

Claims

1. (A) A polysilazane compound having a structure represented by the following formulas (A-1), (A-2), and (A-3), and lacking a hydrosilyl group, (In the formula, R is a group selected from an aliphatic hydrocarbon group having 1 to 6 carbon atoms or a phenyl group, and R may be the same or different in the polysilazane compound. However, the proportion of phenyl groups is 0.3 or less of the total R.) A polysilazane compound characterized in that the ratio of each structural unit to the polysilazane compound satisfies all of the following formulas (1) to (3). (A-1) + (A-2) + (A-3) = 1 …(1) 0.2 ≤ (A-1) ≤ 0.7 …(2) 0 < (A-2) ≤ (A-3) × 4 …(3) 2. The polysilazane compound according to claim 1, characterized in that R in formula (A-1) is a methyl group.

3. The polysilazane compound according to claim 1, characterized in that the ratio of structural units represented by formula (A-1) in the polysilazane compound is in the range of 0.3 to 0.

7.

4. The polysilazane compound according to claim 1, characterized in that the ratio of structural units represented by formula (A-3) in the polysilazane compound is in the range of 0.1 to 0.

7.

5. The polysilazane compound according to claim 1, characterized in that the refractive index of the polysilazane compound after curing at 25°C is in the range of 1.50 to 1.

65.

6. A polysilazane composition characterized by comprising a polysilazane compound according to any one of claims 1 to 5 and a solvent.

7. An adhesive characterized by comprising a polysilazane compound according to any one of claims 1 to 5.

8. An adhesive characterized by comprising the polysilazane composition described in claim 6.

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