Viscosity adjusting solvent, solvent composition and method for producing the same, and method for adjusting solvent viscosity

Abstract

To provide a viscosity adjusting solvent that, even when added to a solvent having a high boiling point and high viscosity, allows viscosity adjustment while suppressing a decrease in the 5% weight loss temperature.SOLUTION: The problem is solved by using, as a viscosity adjusting solvent, a solvent containing 90 wt.% or more of a compound represented by the formula (I) (where R is hydrogen or a C1-C4 alkyl group), for adjusting the viscosity of a solvent which has a higher viscosity than the viscosity adjusting solvent at 25°C as measured with a B-type viscometer and has a 5% weight loss temperature from 160°C to 180°C inclusive.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a viscosity-adjusting solvent. The present invention relates to a solvent composition containing a viscosity-adjusting solvent and a target solvent, and a method for producing the same. The present invention relates to a method for adjusting the viscosity of a solvent using a viscosity-adjusting solvent.

Background Art

[0002] In recent years, in the field of electronics, by printing a paste containing insulating or conductive inorganic particles such as glass paste, silver paste, dielectric paste, solder paste, etc. on a substrate, the formation of electronic circuits and elements, and soldering to the mounting positions of electronic components on the substrate are carried out. Such inorganic particle-containing pastes are required to have a viscosity suitable for printing methods such as screen printing and inkjet printing. Also, in order to remove organic substances from the paste after printing, a sintering treatment is performed at 150°C to 200°C. Therefore, solvents for suspending inorganic particles (also called paste solvents) having high viscosity and high boiling point are used. For example, in Patent Document 1, isobornyl cyclohexanol, a terpene-based solvent having high viscosity and high boiling point, is used for the preparation of inorganic particle-containing paste.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the viscosity of the solvent in which inorganic particles are suspended is too high, it is known to add a low-viscosity solvent such as lower alcohols like ethanol and propanol, or alcohols such as ethylene glycol and terpineol to adjust the viscosity. In Patent Document 1, terpineol is mixed to adjust the viscosity of isobornyl cyclohexanol. However, conventionally, all the solvents added for viscosity adjustment were compounds with a lower boiling point than the paste solvent. Therefore, the evaporation start temperature of the paste solvent after viscosity adjustment was low. In recent years, SiC (silicon carbide) power semiconductors that can operate even at 250°C or higher have been developed and commercialized. Since a high current flows through the power semiconductor, a considerable amount of heat is generated. Therefore, a high melting temperature of 250°C or higher is also required for the solder that joins the power semiconductor to the substrate. For a paste containing a solder with a high melting temperature, it is necessary to use a solvent having a high boiling point and an appropriate viscosity from the viewpoint of solder jointability during reflow. Thus, the solvent for suspending inorganic particles may be required to have not only an appropriate viscosity but also a high boiling point.

[0005] On the other hand, among low-viscosity solvents used to adjust the viscosity of high-viscosity solvents such as paste solvents, those having a high boiling point have not been known so far. An object of the present invention is to provide a viscosity-adjusting solvent that can suppress a decrease in the 5% weight loss temperature and can adjust the viscosity even when added to a solvent having a high boiling point and a high viscosity. Another object of the present invention is to provide a solvent composition using such a viscosity-adjusting solvent, a method for producing the same, and a method for adjusting the viscosity.

Means for Solving the Problems

[0006] The present invention provides a viscosity-adjusting solvent containing 90% by weight or more of a compound represented by the following formula (I). This viscosity-adjusting solvent is used to adjust the viscosity of a target solvent, and the target solvent is a solvent having a viscosity at 25°C measured with a B-type viscometer higher than that of the above viscosity-adjusting solvent and a 5% weight loss temperature of 160°C or higher and 180°C or lower. [Chemical formula] (In the formula, R is hydrogen or an alkyl group having 1 to 4 carbon atoms)

[0007] The present invention provides a solvent composition comprising a viscosity-adjusting solvent containing 90% by weight or more of the compound represented by the above formula (I) and a target solvent. The target solvent is as described above.

[0008] The present invention provides a method for producing a solvent composition, which includes a step of obtaining a solvent composition by mixing a viscosity-adjusting solvent containing 90% by weight or more of the compound represented by the above formula (I) and a target solvent. Further, the present invention provides a method for adjusting the viscosity of a solvent, which includes a step of obtaining a solvent composition by mixing a viscosity-adjusting solvent containing 90% by weight or more of the compound represented by the above formula (I) and a target solvent, and a step of measuring the viscosity of the solvent composition. The target solvent is as described above.

Advantages of the Invention

[0009] According to the viscosity-adjusting solvent of the present invention, the solvent can be adjusted to a desired viscosity while maintaining a high boiling point.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Modes for Carrying Out the Invention

[0011] <Viscosity-Adjusting Solvent> The viscosity-adjusting solvent of the present invention is a solvent used for adjusting the viscosity of a target solvent, and is characterized by containing 90% by weight or more of a compound represented by the following formula (I). In this specification, "adjusting the viscosity of the target solvent" means obtaining a solvent composition having a desired viscosity by mixing the viscosity-adjusting solvent and the target solvent. The target solvent will be described later.

Chemical Formula

[0012] In formula (I), R is hydrogen or an alkyl group having 1 to 4 carbon atoms. The alkyl group having 1 to 4 carbon atoms is preferably an unsubstituted alkyl group, and examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a 1-methylpropyl group, and a t-butyl group. Among them, a methyl group is particularly preferred. The compound represented by formula (I) includes any isomers such as positional isomers and geometric isomers. The compound represented by formula (I) contained in the solvent for viscosity adjustment of the present invention may be a compound having a single structure or a mixture of two or more isomers.

[0013] The solvent for viscosity adjustment of the present invention contains, for example, 90% by weight or more, 90.5% by weight or more, 91% by weight or more, 91.5% by weight or more, 92% by weight or more, 92.5% by weight or more, 93% by weight or more, 93.5% by weight or more, 94% by weight or more, 94.5% by weight or more, 95% by weight or more, 95.5% by weight or more, 96% by weight or more, 96.5% by weight or more, 97% by weight or more, 97.5% by weight or more, 98% by weight or more, 98.5% by weight or more, 99% by weight or more, 99.5% by weight or more, or 100% by weight of the compound represented by formula (I). The solvent for viscosity adjustment of the present invention may contain other substances other than the compound represented by formula (I). Such other substances are not particularly limited, but are preferably those having a 5% weight loss temperature of 160°C or higher, and examples thereof include MTPH. Since MTPH can be used as a raw material for synthesizing the compound represented by formula (I), it may be contained in the solvent for viscosity adjustment of the present invention as an unreacted substance. In a preferred embodiment, the solvent for viscosity adjustment substantially does not contain other substances other than the compound represented by formula (I). Here, the fact that the solvent for viscosity adjustment "substantially does not contain other substances" means that in the solvent for viscosity adjustment, other substances other than the compound represented by formula (I) are contained in a small amount and are not actively added. Examples of the case where other substances are contained in a small amount include the case where they are mixed in trace amounts as impurities or residues, and the case where they are generated in trace amounts due to some chemical reaction or decomposition of the contained components.

[0014] In a preferred embodiment, the compound represented by formula (I) is a compound represented by the following formula (II). The compound represented by formula (II) is isobornyl cyclohexyl acetate (MTPH-Ac).

Chemical formula

[0015] The compound represented by formula (II) includes any isomers such as positional isomers and geometric isomers. The compound represented by formula (II) contained in the viscosity-adjusting solvent of the present invention may be a compound having a single structure or a mixture of two or more isomers.

[0016] In addition to the compound represented by formula (II), examples of the compound represented by formula (I) include isobornyl cyclohexyl formate in which R in formula (I) is hydrogen. Isobornyl cyclohexyl formate has a lower viscosity than MTPH. Also, the 5% weight loss temperature of isobornyl cyclohexyl formate is presumed to be between that of MTPH and MTPH-Ac.

[0017] The viscosity of the solvent for viscosity adjustment of the present invention at 25°C measured with a B-type viscometer depends on the viscosity of the compound represented by formula (I) and is not particularly limited, but is, for example, less than 240 mPa·s. For example, when the solvent for viscosity adjustment consists substantially of MTPH-Ac, the viscosity of the solvent for viscosity adjustment at 25°C measured with a B-type viscometer can be 231 mPa·s. "Consisting substantially of MTPH-Ac" means that the solvent for viscosity adjustment substantially does not contain other substances other than MTPH-Ac. The viscosities presented here are exemplary values. The viscosity can vary depending on the type of isomer of MTPH-Ac and the proportion of isomers contained. The viscosity of the solvent for viscosity adjustment can be measured using a commercially available B-type viscometer (representing a single cylindrical rotational viscometer, also referred to as a Brookfield rotational viscometer). Examples of commercially available B-type viscometers include Brook field DV-III (manufactured by Brookfield). As a specific measurement procedure, an appropriate amount of the solvent for viscosity adjustment adjusted to 25°C is filled into the measurement container of the B-type viscometer, the container is set on the B-type viscometer, and measurement is performed at an appropriate rotational speed using a rotor suitable for the measured viscosity. The viscosity of the compound represented by formula (I) is preferably measured at a rotational speed of 5 rpm by Brook field DV-III (manufactured by Brookfield) using a chamber of SC4-21 and a rotor of SC4-13R.

[0018] The 5% weight loss temperature of the solvent for viscosity adjustment of the present invention is preferably 160°C or higher and 180°C or lower. The lower limit of the 5% weight loss temperature of the solvent for viscosity adjustment is, for example, 160°C, 161°C, 162°C, 163°C, 164°C, 165°C, 166°C, 167°C, 168°C, 169°C or 170°C. The upper limit of the 5% weight loss temperature of the solvent for viscosity adjustment is, for example, 171°C, 172°C, 173°C, 174°C, 175°C, 176°C, 177°C, 178°C, 179°C or 180°C or lower. These upper and lower limit values can be arbitrarily combined. When the solvent for viscosity adjustment consists substantially of MTPH-Ac, the 5% weight loss temperature of the solvent for viscosity adjustment can be 170.5°C. However, this temperature is an exemplary value and can vary depending on the type of isomer of MTPH-Ac and the proportion of isomers contained.

[0019] The 5% weight loss temperature of the viscosity adjusting solvent can be determined by thermogravimetric analysis (TGA). For the measurement by TGA, a commercially available thermal analyzer such as "TG-DTA STA200" manufactured by HITACHI can be used. The measurement atmosphere is an oxygen-containing atmosphere. The oxygen-containing atmosphere may be an air atmosphere or a mixed atmosphere of oxygen and an inert gas such as nitrogen, argon, or helium. Preferably, it is an air atmosphere. The heating rate during thermogravimetric analysis is, for example, 10 °C / min or less. If the heating rate is too fast, the measurement accuracy may decrease, but the heating rate may change during thermogravimetric analysis. For example, at the initial stage of measurement where the solvent does not evaporate, the temperature may be raised at a fast heating rate (such as 20 °C / min), and at around the evaluation temperature, the measurement may be performed at a heating rate of 10 °C / min or less. The vicinity of the evaluation temperature can be determined, for example, by whether the weight change rate is a certain value or more. The lower limit value of the heating rate is not particularly limited, but it is, for example, 1 °C / min.

[0020] The compound represented by the formula (I) can be obtained, for example, by esterifying the compound represented by the following formula (III). The compound represented by the formula (III) is isobornyl cyclohexanol (MTPH).

Chemical formula

[0021] The compound represented by the formula (III) includes any isomers such as positional isomers and geometric isomers. The compound represented by the formula (III) used for the synthesis of the compound represented by the formula (I) may be a compound having a single structure or a mixture of two or more isomers. The compound represented by the formula (III) itself may be obtained by synthesis or a commercially available product may be used. Examples of commercially available products include Telsorb MTPH (manufactured by Nippon Terpene Chemical Co., Ltd.).

[0022] When esterifying MTPH, for example, by reacting MTPH with formic acid, a carboxylic acid having 2 to 5 carbon atoms, a carboxylic acid halide having 2 to 5 carbon atoms, or a carboxylic anhydride having 4 to 10 carbon atoms (a carboxylic anhydride using a carboxylic acid having 2 to 5 carbon atoms), the compound represented by the formula (I) can be obtained. Examples of the carboxylic acid having 2 to 5 carbon atoms include acetic acid, propionic acid, butyric acid, valeric acid, isobutyric acid, pivalic acid, angelic acid, and isovaleric acid. Examples of the carboxylic acid halide having 2 to 5 carbon atoms include acetyl chloride, propionyl chloride, butyryl chloride, valeryl chloride, isobutyryl chloride, pivaloyl chloride, angeloyl chloride, isovaleryl chloride, acetyl bromide, propionyl bromide, butyryl bromide, valeryl bromide, isobutyryl bromide, pivaloyl bromide, angeloyl bromide, isovaleryl bromide, acetyl iodide, propionyl iodide, butyryl iodide, valeryl iodide, isobutyryl iodide, pivaloyl iodide, angeloyl iodide, and isovaleryl iodide. Examples of the carboxylic anhydride having 4 to 10 carbon atoms (a carboxylic anhydride using a carboxylic acid having 2 to 5 carbon atoms) include acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, isobutyric anhydride, pivalic anhydride, angelic anhydride, and isovaleric anhydride. Among them, from the viewpoints of reactivity and environmental load, it is preferable to use a carboxylic anhydride having 4 to 10 carbon atoms (a carboxylic anhydride using a carboxylic acid having 2 to 5 carbon atoms). For example, when esterifying MTPH to synthesize MTPH-Ac, it may be reacted with acetic acid, an acetic acid halide, or acetic anhydride, and preferably with acetic anhydride and MTPH. After completion of the reaction, the reaction product may be subjected to a known purification method such as distillation under reduced pressure to purify the compound represented by the formula (I).

[0023] The weight percentage of the compound represented by the formula (I) in the viscosity-adjusting solvent can be determined by the GC area percentage obtained from the result of analyzing the viscosity-adjusting solvent by gas chromatography (GC). Here, "GC area percentage" refers to the ratio of the peak area of the compound represented by the formula (I) to the total peak area of the viscosity-adjusting solvent containing the compound represented by the formula (I).

[0024] The reaction temperature in the esterification of MTPH is, for example, 50°C to 200°C, preferably 60°C to 180°C, and particularly preferably 70°C to 160°C. The reaction time in the esterification of MTPH is, for example, 12 hours or more. Preferably, after reacting for 12 hours or more, a carboxylic acid, a carboxylic acid halide or a carboxylic anhydride is added once again, and the reaction is continued for 3 hours or more. Whether the compound represented by the formula (I) is produced by the esterification of MTPH can be confirmed by a known measurement method such as IR (infrared spectrophotometer) or NMR (nuclear magnetic resonance apparatus). Preferably, it is confirmed by the ATR (attenuated total reflection measurement) method or the NaCl method using an infrared spectrophotometer. The ATR method is a method of obtaining the absorption spectrum of the sample surface by measuring the light that totally reflects on the sample surface. In the measurement of the compound represented by the formula (I) produced by the esterification of MTPH, the broad peak of the hydroxyl group shown above at 3000 cm -1 The above-mentioned broad peak of the hydroxyl group disappears, and the peak of the carbonyl group derived from the ester appears at 1500 to 2000 cm -1 .

[0025] As used herein, the "target solvent" refers to a solvent that requires viscosity adjustment and forms a solvent composition with the desired viscosity when mixed with the viscosity-adjusting solvent. The target solvent in the present invention is a solvent having a viscosity at 25°C measured with a B-type viscometer higher than that of the viscosity-adjusting solvent of the present invention and a 5% weight loss temperature of 160°C or higher and 180°C or lower. As long as it has these viscosities and 5% weight loss temperature, the target solvent may be a single solvent or a mixture of two or more solvents.

[0026] The target solvent is a solvent containing at least one compound selected from, for example, alcohols and terpenes. Here, since MTPH has an extremely high viscosity of 550000 mPa·s at 25°C measured with a B-type viscometer and a 5% weight loss temperature of 171.1°C, the solvent containing MTPH can be a suitable target solvent. When the target solvent is a solvent containing MTPH, it is preferable that the solvent contains 95% by weight or more of MTPH. Note that the viscosity and 5% weight loss temperature of MTPH shown here are exemplary values. These numerical values can vary depending on the type of MTPH isomers and the ratio of the isomers contained. In a preferred embodiment, the target solvent is a solvent consisting essentially of MTPH. Here, "consisting essentially of MTPH" means that the target solvent substantially does not contain other substances other than MTPH. That the target solvent "substantially does not contain other substances" means that in the target solvent, other substances other than MTPH are contained in a small amount even if any, and such substances are not actively added.

[0027] The viscosity of the target solvent at 25°C measured with a B-type viscometer is not particularly limited as long as it is higher than the viscosity of the viscosity-adjusting solvent of the present invention under the same measurement conditions. The measurement of viscosity with a B-type viscometer is as described above. Preferably, the viscosity of the target solvent at 25°C measured with a B-type viscometer is 240 mPa·s or more and 1000000 mPa·s or less. The lower limit of the viscosity of the target solvent at 25°C measured with a B-type viscometer is preferably 240 mPa·s, 300 mPa·s, 500 mPa·s, 1000 mPa·s, 1500 mPa·s or 2000 mPa·s. The upper limit of the viscosity of the target solvent at 25°C measured with a B-type viscometer is preferably 1000000 mPa·s, 900000 mPa·s, 800000 mPa·s, 700000 mPa·s or 600000 mPa·s. These upper and lower limit values can be arbitrarily combined.

[0028] The lower limit of the 5% weight loss temperature of the target solvent is, for example, 160°C, 161°C, 162°C, 163°C, 164°C, 165°C, 166°C, 167°C, 168°C, 169°C, or 170°C. The upper limit of the 5% weight loss temperature of the target solvent is, for example, 171°C, 172°C, 173°C, 174°C, 175°C, 176°C, 177°C, 178°C, 179°C, or 180°C. These upper and lower limit values can be arbitrarily combined. The 5% weight loss temperature of the target solvent can be determined by measurement using the TGA method, similar to the solvent for viscosity adjustment of the present invention. The details of the measurement are as described above. Thus, since the 5% weight loss temperature of the solvent for viscosity adjustment of the present invention and the target solvent is of the same degree, the 5% weight loss temperature hardly changes even when the solvent for viscosity adjustment of the present invention and the target solvent are mixed. Therefore, when the solvent for viscosity adjustment of the present invention is mixed with the target solvent, a decrease in the 5% weight loss temperature can be suppressed as compared with the case where a low-boiling solvent for viscosity adjustment is mixed.

[0029] The solvent for viscosity adjustment of the present invention can be used, for example, to adjust the viscosity of a solvent for preparing a paste containing insulating or conductive inorganic particles such as glass paste, silver paste, dielectric paste, solder paste, etc. Preferably, it is used to adjust the viscosity of a solvent for preparing a solder paste. Particularly preferably, it is used to adjust the viscosity of a solvent for preparing a solder paste used in the manufacture of power semiconductors.

[0030] In another embodiment, a solvent containing 90% by weight or more of the compound represented by the above formula (I) may be used as a solvent for producing a paste containing insulating or conductive inorganic particles. That is, the present invention provides a paste solvent containing 90% by weight or more of the compound represented by the above formula (I). Examples of the paste include glass paste, silver paste, dielectric paste, solder paste, etc.

[0031] <Solvent Composition> The solvent composition of the present invention is characterized by comprising a viscosity-adjusting solvent containing 90% by weight or more of the compound represented by the above formula (I) and a target solvent. Details of each of the viscosity-adjusting solvent and the target solvent are as described above. The solvent composition of the present invention is a mixture of solvents adjusted to a desired viscosity by mixing the viscosity-adjusting solvent of the present invention and the target solvent. In a preferred embodiment, the compound represented by the above formula (I) is the compound (MTPH-Ac) represented by the above formula (II). As the target solvent, a solvent containing the compound (MTPH) represented by the above formula (III) is preferable, a solvent containing 95% by weight or more of MTPH is more preferable, and a solvent consisting essentially of MTPH is particularly preferable.

[0032] The viscosity of the solvent composition of the present invention is not particularly limited and can be appropriately determined according to the application. The viscosity of the solvent composition can be measured at 25°C using a B-type viscometer in the same manner as the measurement of the viscosity of the viscosity-adjusting solvent of the present invention. Details of the viscosity measurement are as described above. The 5% weight loss temperature of the solvent composition of the present invention is, for example, 160°C or higher and 180°C or lower. As described above, since the 5% weight loss temperatures of the viscosity-adjusting solvent and the target solvent of the present invention are similar, the 5% weight loss temperature hardly changes even when the viscosity-adjusting solvent and the target solvent of the present invention are mixed. Therefore, in the solvent composition of the present invention, a decrease in the 5% weight loss temperature is suppressed compared to the case where a low-boiling viscosity-adjusting solvent is used. The 5% weight loss temperature of the solvent composition can be determined by measurement by the TGA method in the same manner as the viscosity-adjusting solvent of the present invention. Details of the measurement by the TGA method are as described above. Note that both the 5% weight loss temperature and the evaporation start temperature are indicators of evaporation characteristics. If the 5% weight start temperature does not change after the viscosity is adjusted, it is considered that the evaporation start temperature also does not change.

[0033] In the solvent composition of the present invention, the ratio of the viscosity-adjusting solvent to the target solvent is not particularly limited. Depending on the desired viscosity, the viscosity-adjusting solvent and the target solvent can be mixed at any ratio to obtain a solvent composition. The respective ratios of the viscosity-adjusting solvent and the target solvent in the solvent composition can be expressed in weight%. These weight% are determined according to the ratio of the added weight of each of the viscosity-adjusting solvent and the target solvent to the weight of the solvent composition. The method for producing the solvent composition will be described later.

[0034] The use of the solvent composition of the present invention is not particularly limited. For example, it can be used as a solvent for preparing pastes containing insulating or conductive inorganic particles such as glass paste, silver paste, dielectric paste, solder paste, etc. Preferably, it is used as a solvent for preparing solder paste. Particularly preferably, it is used as a solvent for preparing solder paste used in the manufacture of power semiconductors.

[0035] <Method for Producing Solvent Composition> The method for producing the solvent composition of the present invention includes a step of obtaining the solvent composition of the present invention by mixing a viscosity-adjusting solvent containing 90% by weight or more of the compound represented by the above formula (I) with a target solvent. The details of each of the viscosity-adjusting solvent and the target solvent are as described above. In a preferred embodiment, the compound represented by the above formula (I) is the compound (MTPH-Ac) represented by the above formula (II). As the target solvent, a solvent containing the compound (MTPH) represented by the above formula (III) is preferable, a solvent containing 95% by weight or more of MTPH is more preferable, and a solvent consisting essentially of MTPH is particularly preferable.

[0036] The mixing of the viscosity-adjusting solvent and the target solvent can be carried out in a suitable container by a known mixing method using, for example, a stirrer, a magnetic stirrer and a stirring bar. The order of adding the viscosity-adjusting solvent and the target solvent of the present invention to the container is arbitrary. Preferably, the viscosity-adjusting solvent with a lower viscosity is added first, and then the target solvent is added. By placing the viscosity-adjusting solvent with a lower viscosity under the target solvent with a higher viscosity in the container, splashing at the start of stirring can be prevented. The stirring time is, for example, 30 minutes or more, preferably about 1 hour. Although stirring may be carried out for more than 1 hour, attention needs to be paid to the evaporation of the solvent.

[0037] The temperature in the mixing of the viscosity-adjusting solvent and the target solvent is not particularly limited. However, when the viscosity of the target solvent is high (for example, when the viscosity at 25°C is 550,000 mPa·s like MTPH), it may not be possible to mix uniformly at room temperature. In such a case, it is preferable to mix the viscosity-adjusting solvent and the target solvent while heating. By heating, the viscosity of the target solvent decreases and it becomes easier to mix. Even when not heated, frictional heat generated by stirring may cause the temperature to rise between the solvent composition and the container. When mixing while heating, the heating temperature is 50°C or higher and 100°C or lower, preferably 55°C or higher and 90°C or lower, more preferably 60°C or higher and 80°C or lower. If the temperature is below 50°C, the viscosity of the target solvent may not decrease sufficiently and uniform stirring may not be possible. Also, if it exceeds 100°C, the components in the solvent may volatilize. When the components volatilize, the composition ratio of the solvent composition may change and the desired viscosity may not be obtained.

[0038] The mixing ratio of the viscosity-adjusting solvent and the target solvent of the present invention can be determined according to the desired viscosity. For example, when it is desired to obtain a solvent composition with a viscosity slightly lower than that of the target solvent, the addition amount of the viscosity-adjusting solvent can be reduced. Also, when it is desired to significantly lower the viscosity of the target solvent and obtain a solvent composition with a low viscosity, the addition amount of the viscosity-adjusting solvent can be increased.

[0039] In the production method of the present invention, a step of measuring the viscosity of the solvent composition obtained after the step of obtaining the solvent composition can be further included. By including this step, the viscosity of the obtained solvent composition can be known. The viscosity of the solvent composition can be measured at 25°C using a B-type viscometer in the same manner as the measurement of the viscosity of the viscosity-adjusting solvent of the present invention. Details of the viscosity measurement are as described above.

[0040] <Method for Adjusting Viscosity of Solvent> In the method for adjusting the viscosity of the solvent of the present invention, first, a viscosity-adjusting solvent containing 90% by weight or more of the compound represented by the above formula (I) and the target solvent are mixed to obtain the solvent composition of the present invention. Details of each of the viscosity-adjusting solvent and the target solvent are as described above. In a preferred embodiment, the compound represented by the above formula (I) is the compound (MTPH-Ac) represented by the above formula (II). As the target solvent, a solvent containing the compound (MTPH) represented by the above formula (III) is preferable, a solvent containing 95% by weight or more of MTPH is more preferable, and a solvent consisting essentially of MTPH is particularly preferable. Details of the mixing of the viscosity-adjusting solvent and the target solvent are the same as those described in the production method of the solvent composition of the present invention.

[0041] In the method for adjusting the viscosity of the solvent of the present invention, the viscosity of the obtained solvent composition is measured. The viscosity of the solvent composition can be measured at 25°C using a B-type viscometer in the same manner as the measurement of the viscosity of the viscosity-adjusting solvent of the present invention. Alternatively, when the viscosity at the temperature at which the solvent composition is actually used is desired to be known, the viscosity at that temperature may be measured. The lower limit of the temperature in the viscosity measurement is not particularly limited as long as the solvent composition does not solidify, but is, for example, 10°C. The upper limit of the temperature in the viscosity measurement is not particularly limited as long as the solvent composition does not volatilize, but is, for example, 100°C. Also, the viscosity may be measured at a plurality of different temperatures, or the viscosity may be continuously measured within a desired temperature range. In a preferred embodiment, the viscosity is measured at 20°C or higher and 55°C or lower.

[0042] After measuring the viscosity of the obtained solvent composition, if the desired viscosity is not obtained, a viscosity-adjusting solvent or a target solvent may be further added to the solvent composition to readjust the viscosity. For example, when the viscosity of the measured solvent composition is higher than the desired viscosity, a viscosity-adjusting solvent can be further added to the solvent composition. Alternatively, when the viscosity of the measured solvent composition is lower than the desired viscosity, a target solvent can be further added to the solvent composition. After further adding and mixing the viscosity-adjusting solvent or the target solvent, the viscosity of the obtained solvent composition can be measured again to confirm whether the desired viscosity is achieved.

[0043] Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited to these examples.

Examples

[0044] [Production Example 1] Production of Viscosity-Adjusting Solvent 1. Synthesis of Isobornyl Cyclohexyl Acetate 118.2 g of isobornyl cyclohexanol (Tersorb MTPH, Nippon Terpene Chemical Co., Ltd.) was added to a four-necked eggplant flask (300 ml), and the mixture was stirred while heating to 80°C. After heating to 80°C, 76.6 g of acetic anhydride was added dropwise over 30 minutes, and the mixture was stirred at 80°C for 12 hours. After stirring for 12 hours, an additional 15.3 g of acetic anhydride was added, the mixture was heated to 100°C, and stirred at 100°C for 3 hours to cause a reaction. After completion of the reaction, the reaction product was subjected to vacuum distillation using a Claisen tube. The reaction product after vacuum distillation was 127.9 g. When all of the isobornyl cyclohexanol reacted with acetic anhydride, the yield of isobornyl cyclohexyl acetate was 96.8%.

[0045] The above-mentioned Tersorb MTPH as a synthesis raw material and the above-mentioned reaction product after vacuum distillation were analyzed by the ATR method using an infrared spectrophotometer (IRSpirit manufactured by SHIMADZU). In this analysis, the number of integration times was 40 times. The analysis results of Tersorb MTPH and the above-mentioned reaction product are shown in FIGS. 1 and 2. In FIG. 1, at 3320 cm -1A broad peak derived from the hydroxy group of isobornyl cyclohexanol was detected nearby. On the other hand, in Figure 2, the peak near 3320 cm -1 detected in Figure 1 disappeared, and a sharp peak of the carbonyl group derived from the acetyl group was detected near 1735 cm -1 . Also, the horizontal axis of Figures 1 and 2 indicates wavelength (cm -1 ), and the vertical axis indicates transmittance (%T). From these results, it was confirmed that the hydroxy group of isobornyl cyclohexanol reacted with acetic anhydride, acetylation occurred, and isobornyl cyclohexyl acetate could be synthesized.

[0046] 2. Synthesis of isobornyl cyclohexyl formate 118.2 g of isobornyl cyclohexanol (Tersorb MTPH, Nippon Terpene Chemical Co., Ltd.) was added to a 4-neck eggplant flask (300 ml), and the mixture was stirred while heating to 60 °C. After heating to 60 °C, 29.9 g of formic acid was added dropwise over 30 minutes, and the mixture was stirred at 60 °C for 3 hours. After stirring for 3 hours, distillation under reduced pressure was carried out using a Claisen tube. The reaction product after distillation under reduced pressure was 109.1 g. When all of the isobornyl cyclohexanol reacted with formic acid, the yield of isobornyl cyclohexyl formate was 82.5%. The viscosity of the reaction product after distillation under reduced pressure was clearly lower than that of the raw material MTPH.

[0047] The above reaction product after distillation under reduced pressure was analyzed by the NaCl method using an infrared spectrophotometer (FT / IR-460plus manufactured by JASCO Corporation). In this analysis, the number of accumulations was 16 times. The analysis results of the above reaction product are shown in Figure 8. Refer to Figure 1 for the analysis results of the raw material Tersorb MTPH. As described above, in Figure 1, a broad peak derived from the hydroxy group of isobornyl cyclohexanol was detected near 3320 cm -1 . On the other hand, in Figure 8, the peak near 3320 cm -1 detected in Figure 1 disappeared, and a sharp peak of the carbonyl group derived from the formyl group was detected near 1720 cm -1 . Also, the horizontal axis of Figure 8 indicates wavelength (cm -1) and the vertical axis indicates transmittance (%T). From these results, it was confirmed that the hydroxyl group of isobornylcyclohexanol reacted with formic acid, causing formylation and synthesizing isobornylcyclohexyl formate.

[0048] 3. Gas Chromatography Analysis The reaction product after the reduced pressure distillation was subjected to GC analysis using a GC-2014 (manufactured by Shimadzu Corporation) under the following conditions. Column: Inertcap 1MS 30m x 0.25mm Film 0.25μm Inj. / Det. (Inlet and Detector Temperature): 280℃ / 280℃ ·Temperature (column temperature): 120℃ → heating rate 5℃ / min → 260℃ (12 min) Carrier gas: N2 Control mode: Constant linear velocity (linear velocity 30 cm / s) Split ratio: 1 / 100 Analysis time: 40 min Injection volume: 0.5 μl

[0049] As a result of GC analysis, the reaction product after the above vacuum distillation was found to be mainly composed of isobornylcyclohexyl acetate, and the GC area percentage of isobornylcyclohexyl acetate was 92%. Therefore, it was found that the reaction product after the above vacuum distillation contained 92% by weight of isobornylcyclohexyl acetate. In the following experiments, the reaction product after the above vacuum distillation is called "isobornylcyclohexyl acetate" and Tersolve MTPH is called "isobornylcyclohexanol".

[0050] As a result of GC analysis of isobornylcyclohexyl formate synthesized under the same analytical conditions as above, a peak of isobornylcyclohexyl formate was detected between the retention time of isobornylcyclohexyl acetate and that of isobornylcyclohexanol. From this result, it was inferred that the 5% weight loss temperature of isobornylcyclohexyl formate is between that of isobornylcyclohexyl formate and isobornylcyclohexanol.

[0051] 4. Viscosity Measurement Using a B-type viscometer (Brookfield DV-III manufactured by Brookfield), a SC4-21 chamber, and a SC4-13R rotor, the viscosity of isobornyl cyclohexyl acetate was measured at 20 °C, 25 °C, 40 °C, and 55 °C under the measurement condition of a rotational speed of 5 rpm. The viscosity of isobornyl cyclohexanol was measured under the same conditions as above except that the chamber was changed to SC4-6R and the rotor was changed to SC4-14. Also, for comparison, the viscosity of terpineol C (manufactured by Nippon Terpene Chemical Co., Ltd.), a conventional viscosity-adjusting solvent, was measured under the same conditions as isobornyl cyclohexyl acetate. The results are shown in Figure 3.

[0052] Referring to Figure 3, the viscosity of isobornyl cyclohexanol was 2,180,000 mPa·s at 20 °C, 550,000 mPa·s at 25 °C, 11,400 mPa·s at 40 °C, and 800 mPa·s at 55 °C. It was shown that isobornyl cyclohexanol is a very high-viscosity solvent. The viscosity of terpineol C was 85 mPa·s at 20 °C, 54 mPa·s at 25 °C, 20 mPa·s at 40 °C, and 8 mPa·s at 55 °C. It was shown that terpineol C is a low-viscosity solvent. The viscosity of isobornyl cyclohexyl acetate was 364 mPa·s at 20 °C, 231 mPa·s at 25 °C, 65 mPa·s at 40 °C, and 21 mPa·s at 55 °C. Although isobornyl cyclohexyl acetate is synthesized from high-viscosity isobornyl cyclohexanol, as shown in Figure 3, its viscosity was significantly reduced. From these results, it was suggested that isobornyl cyclohexyl acetate can be used as a viscosity-adjusting solvent like terpineol C.

[0053] 5. Thermogravimetric Differential Thermal Analysis Using a thermal analyzer (TG-DTA STA200 manufactured by HITACHI), the thermogravimetric changes of isobornyl cyclohexanol, isobornyl cyclohexyl acetate, and terpineol C (20 mg each) were analyzed under temperature conditions of 40 to 400 °C (heating rate 10 °C / min, air 100 ml / min) or at a constant temperature of 250 °C (air 100 ml / min). The results are shown in Figures 4 and 5. In each figure, "TG%" on the vertical axis indicates the weight (%) of each solvent. Also, the horizontal axis in Figure 4 indicates temperature (°C), and the horizontal axis in Figure 5 indicates elapsed time (minutes).

[0054] Referring to Figure 4, it was shown that most of terpineol C evaporates at about 170 °C. On the other hand, isobornyl cyclohexanol showed only about a 5% weight loss even at about 170 °C, indicating that it is a solvent with a high boiling point. Isobornyl cyclohexyl acetate also showed only about a 5% weight loss at about 170 °C, indicating that it has evaporation characteristics similar to those of isobornyl cyclohexanol. Similar results to those in Figure 4 were also obtained in Figure 5. That is, at a temperature of 250 °C, most of terpineol C evaporated in about 8 minutes, while for isobornyl cyclohexanol and isobornyl cyclohexyl acetate, the time until most of them evaporated was about 12 minutes. Also, as shown in Figure 5, it was shown that isobornyl cyclohexanol and isobornyl cyclohexyl acetate have almost the same evaporation characteristics.

[0055] From the above results of viscosity measurement and thermogravimetric differential thermal analysis, it was shown that isobornyl cyclohexyl acetate has a significantly lower viscosity than isobornyl cyclohexanol while having evaporation characteristics almost equivalent to those of isobornyl cyclohexanol. Therefore, it was suggested that isobornyl cyclohexyl acetate can be used as a solvent for adjusting the viscosity of high-viscosity and high-boiling-point solvents such as isobornyl cyclohexanol with little change in its boiling point.

[0056] [Production Example 2] Production of Solvent Composition Isobornyl cyclohexyl acetate and isobornyl cyclohexanol were mixed, and the viscosity and evaporation characteristics of the resulting mixture (solvent composition) were examined.

[0057] 1. Mixing of a viscosity-adjusting solvent and a target solvent 1.1. Example 1 15 g of isobornyl cyclohexanol and 5 g of isobornyl cyclohexyl acetate were added to a 30 ml sample bottle, and the mixture was stirred at 70 °C for 1 hour to obtain a solvent composition.

[0058] 1.2. Example 2 10 g of isobornyl cyclohexanol and 10 g of isobornyl cyclohexyl acetate were added to a 30 ml sample bottle, and the mixture was stirred at 70 °C for 1 hour to obtain a solvent composition.

[0059] 1.3. Example 3 5 g of isobornyl cyclohexanol and 15 g of isobornyl cyclohexyl acetate were added to a 30 ml sample bottle, and the mixture was stirred at 70 °C for 1 hour to obtain a solvent composition.

[0060] 1.4. Comparative Example 1 10 g of terpineol C and 10 g of isobornyl cyclohexanol were added to a 30 ml sample bottle, and the mixture was stirred at 70 °C for 1 hour to obtain a solvent composition.

[0061] 2. Viscosity measurement Using a B-type viscometer (Brookfield DV-III manufactured by Brookfield), a chamber of SC4-21, and a rotor of SC4-13R, the viscosities of the solvent compositions of Examples 1 to 3 and the solvent composition of Comparative Example 1 were measured at temperatures of 20 °C, 25 °C, 40 °C, and 55 °C under the measurement condition of a rotation speed of 5 rpm. The results are shown in Fig. 6. In the figure, for reference, the data of isobornyl cyclohexanol and isobornyl cyclohexyl acetate are also shown.

[0062] Referring to FIG. 6, the viscosities of Example 1 (MTPH 75%) were 45,000 mPa·s at 20°C, 19,000 mPa·s at 25°C, 1,850 mPa·s at 40°C, and 190 mPa·s at 55°C. The viscosities of Example 2 (MTPH 50%) were 5,140 mPa·s at 20°C, 2,300 mPa·s at 25°C, 360 mPa·s at 40°C, and 60 mPa·s at 55°C. The viscosities of Example 3 (MTPH 25%) were 950 mPa·s at 20°C, 480 mPa·s at 25°C, 90 mPa·s at 40°C, and 25 mPa·s at 55°C. The viscosities of Comparative Example 1 (MTPH: terpineol C = 50:50) were 1200 mPa·s at 20°C, 720 mPa·s at 25°C, 180 mPa·s at 40°C, and 45 mPa·s at 55°C. As shown in FIG. 6, the viscosities of the mixtures of Examples 1 to 3 and Comparative Example 1 were lower than that of isobornyl cyclohexanol alone. Also, from the results of Examples 1 to 3, the viscosity decreased according to the addition amount of isobornyl cyclohexyl acetate.

[0063] 3. Thermogravimetric Suggestive Thermal Analysis Using a thermal analyzer (TG-DTA STA200 manufactured by HITACHI), the thermogravimetric changes of the solvent compositions of Examples 1 to 3 and the solvent composition of Comparative Example 1 (each 20 mg) were measured under the temperature conditions of 40 to 400°C (heating rate 10°C / min, air 100 ml / min). The results are shown in FIG. 7. In the figure, for reference, the data of isobornyl cyclohexanol and isobornyl cyclohexyl acetate are also shown.

[0064] Referring to FIG. 7, it was shown that most of Comparative Example 1 evaporated at about 240°C. On the other hand, the solvent compositions of Examples 1 to 3, isobornyl cyclohexanol, and isobornyl cyclohexyl acetate had only about 50 to 70% weight loss even at about 240°C, indicating that their boiling points were higher than that of the solvent composition of Comparative Example 1. It was shown that even when isobornyl cyclohexyl acetate was mixed with isobornyl cyclohexanol, it had evaporation characteristics similar to those of isobornyl cyclohexanol.

[0065] 4. Summary of the analysis results of each solvent From the results of the above viscosity measurement and thermogravimetric derivative thermogravimetry, the 5% weight loss temperature, 95% weight loss temperature, and viscosity at 25°C of the solvent compositions of Examples 1 to 3 and the solvent composition of Comparative Example 1 are shown in Table 1. For reference, the respective individual numerical values of isobornyl cyclohexanol, isobornyl cyclohexyl acetate, and terpineol C are also shown.

[0066]

Table 1

[0067] From Table 1, it was found that although isobornyl cyclohexyl acetate has a difference in 5% weight loss temperature of only 0.6°C and a difference in 95% weight loss temperature of only 8.7°C compared to isobornyl cyclohexanol, the viscosity has decreased by 99% or more. Further, the solvent compositions of Examples 1 to 3 obtained by mixing isobornyl cyclohexanol and isobornyl cyclohexyl acetate at various ratios have a lower viscosity than isobornyl cyclohexanol, and it was found that the 5% weight loss temperature is 169.7 to 173°C and the 95% weight loss temperature is 252.3 to 260.5°C. On the other hand, the solvent composition of Comparative Example 1 obtained by mixing isobornyl cyclohexanol and terpineol C had a lower viscosity, but the 5% weight loss temperature was 124.1°C and the 95% weight loss temperature was 240.2°C, which was found to be significantly lower than that of isobornyl cyclohexanol.

[0068] From these facts, it can be seen that as the amount of isobornyl cyclohexyl acetate increases, the viscosity tends to decrease. Therefore, it is considered possible to adjust the viscosity of a solvent having a higher viscosity than isobornyl cyclohexyl acetate, such as isobornyl cyclohexanol. Further, it is considered possible to make a similar adjustment for isobornyl cyclohexyl carboxylate having 3 to 5 carbon atoms and isobornyl cyclohexyl formate, which are ester compounds such as isobornyl cyclohexyl acetate. In addition, regarding the viscosity of the solvent, if about 200 is good, it is also conceivable to use isobornyl cyclohexyl acetate alone as the solvent.

Claims

1. A viscosity-adjusting solvent containing 90% by weight or more of a compound represented by the following formula (I), 【Chemical 1】 (wherein R is hydrogen or an alkyl group having 1 to 4 carbon atoms) wherein the viscosity-adjusting solvent is used to adjust the viscosity of a target solvent, wherein the target solvent is a solvent having a viscosity at 25°C measured with a B-type viscometer higher than that of the viscosity-adjusting solvent and a 5% weight loss temperature of 160°C or higher and 180°C or lower, Viscosity-adjusting solvent.

2. The viscosity-adjusting solvent according to claim 1, wherein the compound represented by the formula (I) is a compound represented by the following formula (II). [Chemical Formula 2]

3. The viscosity-adjusting solvent according to claim 2, wherein the target solvent has a viscosity at 25°C measured with a B-type viscometer of 240 mPa·s or more and 1,000,000 mPa·s or less and a 5% weight loss temperature of 160°C or higher and 180°C or lower.

4. The viscosity-adjusting solvent according to any one of claims 1 to 3, wherein the target solvent is a solvent containing a compound represented by the following formula (III). 【Chemical 3】

5. A solvent composition comprising a viscosity-adjusting solvent containing 90% by weight or more of a compound represented by the following formula (I) and a target solvent, 【Chemical Formula 4】 (wherein R is hydrogen or an alkyl group having 1 to 4 carbon atoms) wherein the target solvent is a solvent having a viscosity at 25°C measured with a B-type viscometer higher than that of the viscosity-adjusting solvent and a 5% weight loss temperature of 160°C or higher and 180°C or lower. Solvent composition.

6. The solvent composition according to claim 5, wherein the compound represented by the formula (I) is a compound represented by the following formula (II). 【Chemical Formula 5】

7. The solvent composition according to claim 6, wherein the viscosity of the target solvent at 25°C measured with a B-type viscometer is 240 mPa·s or more and 1,000,000 mPa·s or less and a 5% weight loss temperature of 160°C or higher and 180°C or lower.

8. The solvent composition according to any one of claims 5 to 7, wherein the target solvent is a solvent containing a compound represented by the following formula (III). 【Chemical Formula 6】

9. A step of obtaining a solvent composition by mixing a viscosity-adjusting solvent containing 90% by weight or more of a compound represented by the following formula (I) and a target solvent, a step of measuring the viscosity of the solvent composition, and including wherein the target solvent is a solvent having a viscosity at 25°C measured with a B-type viscometer higher than that of the viscosity-adjusting solvent and a 5% weight loss temperature of 160°C or higher and 180°C or lower, A method for adjusting the viscosity of a solvent. 【Chemical Formula 7】 (wherein R is hydrogen or an alkyl group having 1 to 4 carbon atoms)

10. A step of obtaining a solvent composition by mixing a viscosity-adjusting solvent containing 90% by weight or more of a compound represented by the following formula (I) with a target solvent, wherein the target solvent is a solvent having a viscosity at 25°C measured with a B-type viscometer higher than that of the viscosity-adjusting solvent and a 5% weight loss temperature of 160°C or higher and 180°C or lower, A method for producing a solvent composition. 【Chemical Formula 8】 (In the formula, R is hydrogen or an alkyl group having 1 to 4 carbon atoms)

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