Solvent composition

Abstract

A solvent composition is provided, which may be a mixture of two or more components. The molecule in the solvent comprises a carbonyl group, an ether linkage, and a group selected from-OH and-NH2.

Description

[0001] introduction

[0002] Photosensitive materials are widely used, for example, in the manufacture of printed circuits in the electronics industry. One useful class of photosensitive materials is photosensitive polyimides. Generally speaking, polyimides are typically the reaction product of one or more dianhydride monomers and one or more diamine monomers. In the formation of photosensitive polyimides, one or more of the monomers typically has one or more substituent groups that react with photons to form groups that initiate and / or participate in crosslinking reactions.

[0003] In a common process for making printed circuits, a layer containing a photosensitive polyimide is present on a surface. Some portions of the layer are exposed to radiation (e.g., ultraviolet light), while other portions are not. The portions exposed to radiation undergo crosslinking, while the unexposed portions do not. In this process, the layer is then contacted with an alkaline solution, which degrades the uncrosslinked polyimide to produce monomeric portions. The layer is then washed with one or more solvents to dissolve the monomeric portions. The layer is then washed with water to remove the solvent and the dissolved monomeric portions.

[0004] US 2012 / 0276741 describes a cleaning process using a liquid mixture containing at least two benign chemicals that can form eutectics.

[0005] It is desirable to provide a solvent suitable for dissolving the monomeric moieties produced in a process such as the one described above. Desirable properties of such a solvent include one or more of the following: the relevant monomers have good solubility in the solvent; the solvent is relatively nonvolatile; the solvent is not considered reproductively toxic; the solvent has a melting point of 65°C or less; the solvent is relatively easy to prepare; and the solvent has very few or no halogen atoms. It is also desirable that the solvent have one or more of the following properties: the solvent is relatively inexpensive; and the solvent is biodegradable. Summary of the Invention

[0006] A first aspect is a solvent composition SC1, comprising one or more compounds C1, one or more compounds C2 and one or more compounds C3,

[0007] a) wherein each compound C1 comprises one or more chemical groups selected from the list consisting of -NH2 and -OH, wherein the -OH group, if present, can or can not be part of a carboxyl group;

[0008] b) wherein each compound C2 contains one or more ether bonds;

[0009] c) wherein each compound C3 contains one or more carbonyl groups, which may or may not be part of a carboxyl group;

[0010] d) wherein a single compound can be used as two or more of Compound C1, Compound C2, and Compound C3;

[0011] e) wherein the solvent composition SC1 has a melting point of 65° C. or less;

[0012] f) wherein the solvent composition SC1 has no halogen atoms or has a halogen atom based on the solvent composition

[0013] halogen atoms in an amount of 0.1 wt% or less based on the weight of SC1;

[0014] g) wherein there is a temperature T1 of greater than or equal to 15° C. and less than or equal to 40° C., wherein the solvent composition SC1 is liquid at temperature T1, and wherein at temperature T1, the solubility of monomer A in the solvent composition SC1 is 0.5 wt.-% or more, based on the weight of the solvent composition SC1, wherein monomer A has the following structure:

[0015]

[0016] h) wherein at the temperature T1, the solubility of monomer B in the solvent composition SC1 is 0.5 wt. % or more, based on the weight of the solvent composition SC1, wherein monomer B has the following structure:

[0017]

[0018] A second aspect is a solvent composition SC2 comprising one or more mixtures of compounds selected from the group consisting of:

[0019] M1) A mixture consisting of urea, glycolic acid and diethylene glycol n-butyl ether, wherein the weight percentages of urea, glycolic acid and diethylene glycol n-butyl ether meet one of criteria A) or criteria B), wherein all percentages are by weight based on the weight of mixture M1, wherein pU is the percentage of urea, pGA is the percentage of glycolic acid, and pDBE is the percentage of diethylene glycol n-butyl ether, and wherein criteria A) and criteria B) are defined as follows:

[0020] Criteria A): pGA is 8% or more, pGA is less than 32%, pU is 0% or more, pU is 30% or less, and pDBE = 100-(pU +

[0021] pGA);

[0022] Standard B): pGA is 32% or more, pGA is 50% or less, pU is 10%

[0023] or higher, pU is 30% or lower, and pDBE=100-(pU

[0024] +pGA);

[0025] M2) a mixture of urea and diethylene glycol, wherein the molar ratio of urea to diethylene glycol is from 0.1:1 to 0.3:1;

[0026] M3) a mixture consisting of glycolic acid and diethylene glycol, wherein the molar ratio of glycolic acid to diethylene glycol is from 0.1:1 to 5:1;

[0027] M4) and a mixture of urea and 2-phenoxyethanol, wherein the molar ratio of urea to 2-phenoxyethanol is from 0.1:1 to 0.3:1. DETAILED DESCRIPTION

[0028] The following terms are defined herein as follows.

[0029] As used herein, an ether bond is a chemical group in which an oxygen atom is connected to two carbon atoms via a single bond. Each of the two carbon atoms is in turn connected only to hydrogen atoms or other carbon atoms.

[0030] As used herein, a carbonyl group is a group in which a carbon atom is connected to an oxygen atom via a double bond. The carbon atom is connected to two other atoms via single bonds, and those other atoms can be of any type.

[0031] As used herein, the melting point of a composition is the onset temperature of a melting transition as measured by differential scanning calorimetry (DSC) at 10°C / minute. If more than one transition is detected, the melting point of the composition is determined to be the onset temperature of the transition occurring at the lowest temperature of all transitions.

[0032] As used herein, a "polyimide" is a polymer having the following structure (I):

[0033]

[0034] In structure (I), the ellipses represent chemical groups, R is a chemical group, and n is 10 or higher.

[0035] The ratios presented herein are characterized as follows. For example, if a ratio is referred to as 3:1 or greater, then the ratio may be 3:1 or 5:1 or 100:1, but not 2:1. This characterization can be generally stated as follows. When a ratio is referred to herein as X:1 or greater, it is meant that the ratio is Y:1, where Y is greater than or equal to X. For another example, if a ratio is referred to as 15:1 or less, then the ratio may be 15:1 or 10:1 or 0.1:1, but may not be 20:1. Generally speaking, when a ratio is referred to herein as W:1 or less, it is meant that the ratio is Z:1, where Z is less than or equal to W.

[0036] The present invention relates to a solvent composition, designated herein as SC1, comprising one or more compounds of type designated herein as C1, one or more compounds of type designated herein as C2, and one or more compounds of type designated herein as C3. In some embodiments, one or more compounds are present that have properties that cause the compound to belong to two or more of the C1, C2, and / or C3 types.

[0037] Compound C1 contains one or more chemical groups selected from -NH2 and -OH in its molecule. Compounds containing -OH groups are considered to be C1 compounds herein, regardless of whether the -OH group is attached to a carbon atom that is also attached to an oxygen or nitrogen atom. For example, compounds containing -OH groups are considered to be C1 compounds herein, regardless of whether the -OH group is part of a carboxyl group. Preferred compounds C1 contain two or more -NH2 groups or two or more -OH groups. Preferred compounds C1 have 5 or fewer carbon atoms; more preferably four or fewer; more preferably 3 or fewer; more preferably two or fewer. Preferred compounds C1 are urea, glycolic acid, 2-phenoxyethanol, glycerol, lactic acid, ethylene glycol, diethylene glycol, glucose, sorbitol, diethylene glycol n-butyl ether, and mixtures thereof; more preferably urea, glycolic acid, lactic acid, glucose, and mixtures thereof; more preferably urea, glycolic acid, and mixtures thereof.

[0038] Compound C2 contains one or more ether bonds. Preferred Compound C2 has 4 or more carbon atoms; more preferably 6 or more; more preferably 8 or more. Preferred Compound C2 has 12 or fewer carbon atoms; more preferably 10 or fewer; more preferably 8 or fewer. Preferred Compound C2 is 2-phenoxyethanol, diethylene glycol, and diethylene glycol n-butyl ether.

[0039] Compound C3 contains one or more carbonyl groups. Preferred Compound C3 are glucose, lactic acid, glycolic acid, and urea; more preferred are glycolic acid and urea. Preferred Compound C3 has 5 or fewer carbon atoms; more preferred are 4 or fewer; more preferred are 3 or fewer; and more preferred are 2 or fewer. Preferred Compound C3 also conforms to Compound C1. Preferably, each Compound C3 present also conforms to Compound C1.

[0040] In some embodiments, solvent composition SC1 may contain one or more "other" compounds, defined herein as compounds that do not qualify as any of Compound C1, Compound C2, or Compound C3. In preferred embodiments, the amount of "other" compounds in solvent composition SC1 is relatively small or zero. That is, the total amount of all "other" compounds, based on the weight of solvent composition SC1, is preferably from 0% to 20% by weight; more preferably from 0% to 5% by weight; more preferably from 0% to 1% by weight; more preferably from 0% to 0.2% by weight; more preferably from 0% to 0.05% by weight; and more preferably from 0% to 0.01% by weight. In some embodiments, the amount of "other" compounds in solvent composition SC1 is zero.

[0041] The solvent composition SC1 has a melting point. Preferably, the melting point of the solvent composition SC1 is 65° or lower; more preferably 55°C or lower; more preferably 40°C or lower; more preferably 35°C or lower; more preferably 30°C or lower.

[0042] Preferably, in the practice of the present invention, one or more compounds C1 have a melting point. The melting point of the solvent composition SC1 will preferably be lower than the melting point of one or more compounds in compound C1. Similarly, preferably, one or more compounds C2 have a melting point, and preferably, the melting point of the solvent composition SC1 will be lower than the melting point of one or more compounds in compound C2. Additionally, preferably, one or more compounds C3 have a melting point, and preferably, the melting point of the solvent composition SC1 will be lower than the melting point of one or more compounds in compound C3. Preferably, the melting point of the solvent composition SC1 is lower than each melting point of each compound C1, each compound C2, and each compound C3.

[0043] As an illustrative, non-limiting example of a comparison of these preferred melting points, it is useful to consider an embodiment in which solvent composition SC1 contains two compounds: one compound (X) that corresponds only to compounds C1 and C3, and another compound (Y) that corresponds only to compound C2. In this preferred embodiment, the melting point of solvent composition SC1 is lower than both the melting point of compound X and the melting point of compound Y.

[0044] Halogen atoms are completely absent from the solvent composition SC1, or if present, are present in limited amounts. The amount of halogen atoms in the solvent composition SC1 is from 0% to 0.1% by weight, preferably from 0% to 0.03% by weight, more preferably from 0% to 0.01% by weight, more preferably from 0.003% by weight, and more preferably from 0% to 0.001% by weight, based on the weight of the solvent composition SC1.

[0045] The solvent composition SC1 is liquid within a temperature range, and the range includes at least one temperature T1 at which the solvent composition SC1 is liquid, wherein T1 is greater than or equal to 15° C. and T1 is less than or equal to 65° C. Preferably, there is a T1 greater than or equal to 20° C. Preferably, there is a T1 less than or equal to 30° C.

[0046] It is expected that the solvent composition SC1 will be able to dissolve the monomer fraction produced during the degradation of the photosensitive polyimide. To evaluate this property, monomer A and monomer B (as defined above) were used. Many monomers used to prepare photosensitive polyimides have strong similarities to (or are identical to) monomer A or monomer B. It is expected that because the solvent composition SC1 can usefully dissolve high concentrations of monomer A and monomer B, the solvent composition SC1 will also be able to usefully dissolve high concentrations of any monomer fraction produced during the degradation of the photosensitive polyimide.

[0047] There is a temperature T1 as defined above at which the solubility of monomer A in solvent composition SC1 is 0.5% by weight or more, preferably 1% by weight or more, more preferably 2% by weight or more, more preferably 5% by weight or more, based on the weight of solvent composition SC1. At the same temperature T1, the solubility of monomer B in solvent composition SC1 is 0.5% by weight or more, preferably 1% by weight or more, more preferably 2% by weight or more, more preferably 5% by weight or more, based on the weight of solvent composition SC1.

[0048] The solvent composition SC1 is preferably soluble in water at 25° C. Specifically, the preferred amount of the solvent composition SC1 to be dissolved in water at 25° C. is 1 wt % or more, more preferably 2 wt % or more, more preferably 5 wt % or more, more preferably 10 wt % or more, based on the weight of water.

[0049] Preferably, the solvent composition SC1 does not cause teratogenic effects when tested in experimental animals. Preferably, the solvent composition SC1 does not need to be labeled as "toxic to reproduction" according to the guidelines of the 2012 publication "Hazard Communication Standard" published by the US Occupational Health and Safety Administration in the United States Code of Federal Regulations 29 CFR 1910.1200.

[0050] Four specific mixtures are contemplated as useful embodiments of the present invention; these mixtures are labeled herein as M1, M2, M3, and M4 (defined below). A solvent composition containing one or more of these mixtures is labeled herein as "solvent composition SC2," although solvent composition SC2 may also correspond to solvent composition SC1 as defined above.

[0051] Mixture M1 consists of a mixture of urea, glycolic acid, and diethylene glycol n-butyl ether. Mixture M1 is conveniently described using weight percentages based on the weight of solvent mixture SC2. The weight percentages of urea, glycolic acid, and diethylene glycol n-butyl ether are denoted herein as pU, PGA, and pDEGE, respectively. Mixture M1 meets either Criteria A or Criteria B as described below:

[0052] Benchmark A: pGA is 8% or higher; pGA is less than 32%; pU is higher than 0%; pU is 30% or lower; and pDEGE = 100 - (pGA + pU);

[0053] Benchmark B: pGA is 32% or higher; pGA is 50% or lower; pU is 10% or higher; pU is 30% or lower; and pDEGE is 100-(pGA+pU).

[0054] The mixtures M2, M3 and M4 are most conveniently described using molar ratios.

[0055] Mixture M2 consists of a mixture of urea and diethylene glycol, wherein the molar ratio of urea to diethylene glycol is from 0.1:1 to 0.3:1.

[0056] Mixture M3 consists of a mixture of glycolic acid and diethylene glycol, wherein the molar ratio of glycolic acid to diethylene glycol is from 0.1:1 to 5:1.

[0057] Mixture M4 consisted of a mixture of urea and 2-phenoxyethanol, wherein the molar ratio of urea to 2-phenoxyethanol was from 0.1:1 to 0.3:1.

[0058] Embodiments of the invention are envisaged in which the solvent composition SC2 contains exactly one of the mixtures M1, M2, M3 or M4. Embodiments are also envisaged in which the solvent composition SC2 contains two or more of the mixtures M1, M2, M3 and M4.

[0059] Preferably, the total amount of all mixtures M1, M2, M3 and M4, based on the weight of the solvent composition SC2, is 80% to 100% by weight; more preferably 90% or 100% by weight; more preferably 95% to 100% by weight.

[0060] Preferably, halogen atoms are completely absent from solvent composition SC2, or, if present, are present in limited amounts. The amount of halogen atoms in solvent composition SC2, based on the weight of solvent composition SC1, is preferably from 0% to 0.1% by weight; preferably from 0% to 0.03% by weight; more preferably from 0% to 0.01% by weight; more preferably from 0% to 0.003% by weight; more preferably from 0% to 0.001% by weight.

[0061] In one aspect of the present invention, a solution is formed using solvent composition SC1 or solvent composition SC2 as a solvent, and the solute comprises a degradation product of a photosensitive polyimide. In a preferred embodiment, the solute comprises one or more compounds selected from the group consisting of: a compound having the structure of monomer A, which may have a substituent group; a compound having the structure of monomer B, which may have a substituent group; and mixtures thereof.

[0062] The following are examples of the present invention. Unless otherwise stated, operations were carried out at room temperature (approximately 23°C).

[0063] The materials used are as follows. All materials were obtained from Sinopharm. The water solubility values shown (literature values, as published in Wikipedia) are at 25°C.

[0064] Table 1: Materials

[0065]

[0066] In order to prepare the mixture for testing, each component of the required amount is added to a transparent bottle. The sample is heated and shaken in a 70 ° C baking oven for 1 hour, then taken out and allowed to return to room temperature (about 23 °). The bottle is then photographed using a phase identification and characterization device (PICA-II), which is constructed by Dow for imaging and analysis of research samples. Various binary mixtures (that is, mixtures of just two compounds) have been formed, as shown in Table 2A. In Table 2A, "Com" means component, "op" means opaque, and "nt" means untested. Binary mixtures are characterized in this article by their molar ratio.

[0067] Table 2A: Binary Mixtures

[0068]

[0069] Some samples in Table 2 were selected for further testing and given the following labels. The molar ratio shown is Com 1:Com 2. Melting points were measured by DSC as described above.

[0070] Table 2B: Binary mixtures selected from Table 2A

[0071] Label Com1 Com2 molar ratio Melting point (℃) CE2 urea GA 1:1 Less than -80 CE3 urea LA 1:1 Less than -80 CE4 urea EG 0.67:1 Less than -80 CE5 GA EG 1:1 nt IE2 urea DEG 0.25:1 Less than -80 IE3 GA DEG 1:1 nt IE4 urea POE 0.25:1 nt

[0072] Ternary mixtures of urea, GA, and DBE were also formed, as shown in Table 3. The amounts shown are weight percent based on the weight of the ternary mixture.

[0073] Table 3: Ternary mixtures of urea, GA, and DBE

[0074] Mixture number wt% urea %GA by weight wt% DBE Appearance T21 8 88 4 opaque T24 17 72 11 opaque T06 6 69 25 opaque T19 21 60 19 opaque T12 11 53 46 opaque T03 45 52 13 opaque T02 27 46 27 transparent T15 48 43 9 opaque T20 7 42 51 opaque T01 42 36 22 opaque T07 22 32 46 transparent

[0075] Table 3 (continued): Ternary mixtures of urea, GA, and DBE

[0076] Mixture number wt% urea %GA by weight wt% DBE Appearance T05 66 29 5 opaque T13 5 27 68 transparent T16 37 26 37 opaque T11 58 24 18 opaque T08 18 21 61 transparent T14 52 18 30 opaque T22 31 14 55 opaque T10 70 10 20 opaque T17 44 8 48 opaque T04 86 7 17 opaque T23 24 6 70 opaque T18 62 5 33 opaque

[0077] A mixture labeled herein as "IE1" was also formed, having 7.8 wt% urea, 29.4 wt% GA, and 62.8% DBE, which was also transparent. Sample IE1 had a 1:1:1 molar ratio of urea:GA:DBE. Sample IE1 had a melting point of less than -80°C.

[0078] The samples in Table 2B and Sample IE1 are liquids at room temperature (approximately 23°C).

[0079] Each component, sample and sample IE1 in Table 2B were examined by FTIR (Fourier Transform Infra Red) analysis. FTIR spectra were obtained using a Thermo Scientific Nicolet 5700 FTIR spectrometer in ATR mode with a diamond crystal at 4 cm -1 The resolution is 4000cm -1 Up to 5000cm -1 The image was obtained by performing 32 scans in the area.

[0080] The FTIR spectrum of each mixture was compared to the FTIR spectrum of each of the components of the mixture. For each mixture, the FTIR spectrum was the sum of the FTIR spectra of the components of the mixture. This result is expected to indicate that in each mixture, the components did not undergo any chemical reactions.

[0081] The samples in Table 2B, sample IE1, and NMF were tested to determine whether each was a good solvent for monomer A and monomer B. To perform these tests, 0.125 g of monomer A, 0.125 g of monomer B, and 2.5 g of the sample solvent were placed in a vial and photographed using a PICA-II instrument. For each sample, the height of the monomer mixture in the vial was 4 mm. The vial was placed in an oven at 54° C. without stirring for 13 hours. The vial was returned to room temperature and photographed again using the PICA-II instrument. The height of the solid residue was observed. The residue, if any, was considered to be undissolved monomer A, undissolved monomer B, or a mixture thereof. The solvency % of each solvent composition was determined as follows:

[0082] Solvability % = 100*(1-[(final height of monomer) / (initial height of monomer)])

[0083] Table 4: Solvent composition dissolving capacity

[0084]

[0085] Based on the results in Table 4, the inventive solvent compositions IE1, IE2, IE3, and IE4 are excellent solvents for monomers A and B, while the comparative solvent compositions CE2, CE3, CE4, and CE5 are poor solvents for monomers A and B. Solvent NMF is a good solvent for monomers A and B, but NMF has other undesirable properties and falls outside the scope of the present invention. It was observed that in each of the samples with a solvency of 100%, the concentration of monomer A in the final solution was 5% by weight, based on the weight of the solvent composition, and the concentration of monomer B in the final solution was 5% by weight, based on the weight of the solvent composition.

[0086] In interpreting the results, it is important to note that inventive examples IE1, IE2, IE3, and IE4 have molecules with all three required functional groups: (1) -NH2 or -OH, (2) a carbonyl group, and (3) an ether linkage, and are all good solvents for both Monomer A and Monomer B. In contrast, comparative examples CE2, CE3, CE4, and CE5 each lack any ether linkages and are all poor solvents for both Monomer A and Monomer B.

[0087] It should be noted that all components used in the inventive mixtures IE1, IE2, IE3 and IE4 have a solubility of 1 wt% or greater in water at 25° C. Therefore, it is believed that these inventive mixtures also have a solubility of 1 wt% or greater in water at 25° C.

[0088] It should also be noted that the inventive mixtures IE1, IE2, IE3 and IE4 are mixtures of widely available components without chemical reactions. Therefore, these mixtures are considered to be relatively easy to prepare and relatively inexpensive.

Claims

1. A solvent composition SC1 comprising one or more compounds C1, one or more compounds C2 and one or more compounds C3, a) wherein each compound C1 comprises one or more chemical groups selected from the list consisting of -NH2 and -OH, wherein the -OH group, If present, can or can not be part of a carboxyl group; b) wherein each compound C2 contains one or more ether bonds; c) wherein each compound C3 comprises one or more carbonyl groups, which may or may not be part of a carboxyl group; d) wherein a single compound can be used as two or more of Compound C1, Compound C2, and Compound C3; e) wherein the solvent composition SC1 has a melting point of 65° C. or less; f) wherein the solvent composition SC1 has no halogen atoms or has halogen atoms in an amount of 0.1 wt.-% or less, based on the weight of the solvent composition SC1; g) wherein there is a temperature T1 of greater than or equal to 15° C. and less than or equal to 40° C., wherein the solvent composition SC1 is liquid at temperature T1, and wherein at temperature T1, the solubility of monomer A in the solvent composition SC1 is 0.5 wt.-% or more, based on the weight of the solvent composition SC1, wherein monomer A has the following structure: h) wherein at said temperature T1, the solubility of monomer B in said solvent composition SC1 is 0.5 wt% or more based on the weight of said solvent composition SC1, wherein monomer B has the following structure: 2 . The solvent composition SC1 according to claim 1 , wherein the solvent composition SC1 has no reproductive toxicity. 3 . The solvent composition SC1 according to claim 1 , wherein the solubility of the solvent composition SC1 in water at 25° C. is 1% by weight or more based on the weight of the water.

4. The solvent composition SC1 according to claim 1, wherein the total amount of all compounds that do not meet any one of compound C1, compound C2 or compound C3 is 0 wt% or an amount less than 20 wt% based on the total weight of the solvent composition SC1. 5 . The solvent composition SC1 according to claim 1 , wherein the solvent composition SC1 comprises one or more compounds C1 having two or more —OH groups or two or more —NH 2 groups per molecule. 6 . The solvent composition SC1 according to claim 5 , wherein the solvent composition SC1 comprises one or more compounds C1 comprising urea, glycolic acid or a mixture thereof. 7 . The solvent composition SC1 according to claim 1 , wherein the melting point of the solvent composition SC1 is lower than the melting point of one or more compounds in the compound C1.

8. A solvent composition SC2 comprising one or more mixtures of compounds selected from the group consisting of: M1) A mixture consisting of urea, glycolic acid and diethylene glycol n-butyl ether, wherein the weight percentages of urea, glycolic acid and diethylene glycol n-butyl ether meet one of criteria A) or criteria B), wherein all percentages are by weight based on the weight of mixture M1, wherein pU is the percentage of urea, pGA is the percentage of glycolic acid, and pDBE is the percentage of diethylene glycol n-butyl ether, and wherein criteria A) and criteria B) are defined as follows: Criterion A): pGA is 8% or more, pGA is less than 32%, pU is 0% or more, pU is 30% or less, and pDBE=100-(pU+pGA); Criterion B): pGA is 32% or more, pGA is 50% or less, pU is 10% or more, pU is 30% or less, and pDBE=100-(pU+pGA); M2) a mixture of urea and diethylene glycol, wherein the molar ratio of urea to diethylene glycol is from 0.1:1 to 0.3:1; M3) a mixture consisting of glycolic acid and diethylene glycol, wherein the molar ratio of glycolic acid to diethylene glycol is from 0.1:1 to 5:1; M4) and a mixture of urea and 2-phenoxyethanol, wherein the molar ratio of urea to 2-phenoxyethanol is from 0.1:1 to 0.3:

1. 9 . The solvent composition SC2 according to claim 7 , wherein the total amount of all mixtures M1, M2, M3 and M4 is 80% to 100% by weight, based on the weight of the composition SC2.

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