JP7093663B2 - Curable resin composition and its manufacturing method - Google Patents

Description

The present invention relates to a curable resin composition and a method for producing the same.

Polysiloxane paints for the purpose of extending the life of the coating film, especially high weather resistance and high hardness, have been studied for a long time. This is because the siloxane bond forming the polysiloxane is energetically strong and therefore difficult to decompose by heat or ultraviolet rays, and it is easy to form a dense crosslinked film having a small molecular weight between crosslink points. These polysiloxanes are generally synthesized by hydrolysis and condensation reaction of a silane monomer having an alkoxylyl group called a silane coupling agent, and further, from the viewpoint of cost, a silane coupling agent commercially available. It was common to use.

Considering the environment and health, the demand for water-based polysiloxane will increase, but polysiloxane alone synthesized from commercially available silane coupling agents is structurally difficult to water-based, so water-soluble resins and emulsifiers are used. Water systemization by co-emulsification was common. For example, Patent Documents 1 and 2 describe a method of water-based formation by co-emulsification using a water-soluble resin or an emulsifier.

JP-A-11-172200 JP-A-2010-196034

However, the above method has a problem that a transparent coating film cannot be obtained due to deterioration of water resistance and weather resistance due to the additive origin and poor film formation. In Patent Document 1, the amino group is neutralized with an acid to form a salt, so that polysiloxane alone is solubilized without using a water-soluble resin or an emulsifier. The coating film using the resin produced by this method has a problem that the water resistance is lowered because it contains a large amount of water-based groups. Further, in Patent Document 2, when the mass ratio of the structure derived from polysiloxane in the composite resin composition is 65% or more, the viscosity is remarkably increased and gelation is caused, so that it is difficult to make the polysiloxane alone water-soluble. There was a problem.

In view of the above, the present invention includes a glycidyl group-containing modified polysiloxane resin, which has excellent storage stability, can be stored for a long time, and can provide a coating film having high water resistance, weather resistance and transparency. It is an object of the present invention to provide a curable resin composition and a method for producing the same.

The present invention is a curable resin composition containing a glycidyl group-containing modified polysiloxane resin, wherein the glycidyl group-containing modified polysiloxane resin contains at least one of the following structural units (I) to (V), and is described above. The composition ratios of the structural units (I) to (V) satisfy (d + e) / (a + b + c + d + e) ≧ 0.7, and the content of the glycidyl group with respect to the total solid content of the glycidyl group-containing modified polysiloxane resin is 12% by weight or more. In the curable resin composition, water is contained in an amount of 30% by weight or more and alcohol is contained in an amount of 10% by weight or less based on the total solid content of the glycidyl group-containing modified polysiloxane resin. Regarding.

In the formula, a to e indicate an integer of 0 or more, and d + e is 1 or more.
R ¹ represents a hydrogen atom, a methyl group, an ethyl group, or a propyl group.
^R2 represents a substituted or unsubstituted vinyl group, a phenyl group or a cyclic or acyclic alkyl group having 1 to 8 carbon atoms, and has at least one or more glycidyl groups. R ² may be the same or different.

The curable resin composition preferably has a silicon content of 15% by weight or more based on the total solid content of the glycidyl group-containing modified polysiloxane resin.

The curable resin composition is 3-glycidyloxypropyltrimethoxysilane single condensation, or 3-glycidyloxypropyltrimethoxysilane and methyltrimethoxysilane, vinyltrimethoxysilane, dimethyldimethoxysilane, or 3-glycidyloxypropyl. It is preferably synthesized by co-condensation with one or more silane compounds selected from four types of methyldimethoxysilane.

The curable resin composition contains ^R2 which is a methyl group in the structural units (I) to (V), and the content of the methyl group contained in the total amount of the glycidyl group-containing modified polysiloxane resin is 2% by weight. It is preferably% or more and 12% by weight or less.

The present invention also comprises a step of obtaining the glycidyl group-containing modified polysiloxane resin by hydrolyzing and dehydrating and condensing the silane compound using an acidic catalyst, and the curable resin composition comprises the curable resin composition. The step of setting the water content to 30% by weight or more based on 100% by weight of the total amount of the substance, and setting the alcohol content to 10% by weight or less based on 100% by weight of the total amount of the curable resin composition. The present invention relates to a production method comprising a step, wherein the glycidyl group-containing modified polysiloxane resin contains 12% by weight or more of the glycidyl group with respect to the total amount of solid content.

According to the present invention, curability containing a glycidyl group-containing modified polysiloxane resin, which has excellent storage stability, can be stored for a long time, and can provide a coating film having high water resistance, weather resistance, and transparency. A resin composition and a method for producing the same can be provided.

Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these embodiments.

(Curable resin composition)
The curable resin composition of the present invention contains a glycidyl group-containing modified polysiloxane resin as an essential component. The glycidyl group-containing modified polysiloxane resin contains a glycidyl group, which is a polar group, and is an oligomer, so that it is water-soluble. Further, since the glycidyl group-containing modified polysiloxane resin contains a large amount of D1, T1 and T2 structures (which will be described later for D1, T1 and T2) which are partial condensates, and has a large amount of silanol groups which are polar groups. Shows water solubility.

In addition, the curable resin composition of the present invention has a high molecular weight due to the progress of condensation during curing, and the amount of silanol groups is also reduced, so that the water solubility is lowered and a cured coating film having high water resistance can be obtained. Further, by reacting the glycidyl group contained in the curable resin composition at the time of curing, it is possible to increase the water resistance by increasing the molecular weight of the curable resin composition.

The glycidyl group-containing modified polysiloxane resin in the present invention is a resin having a structure in which the terminal of a propyl group directly connected to a silicon atom is replaced with a glycidyl group, and at least one of the above structural units (I) to (V) is used. include.

There are five types of the above-mentioned structural units, and each structural unit may or may not be included. Therefore, the repetition numbers a, b, c, d and e of each of these structural units indicate integers of 0 or more, respectively. However, when none of these constituent units is contained, it is excluded, and since any one of them is always contained in the polysiloxane resin, the total of a, b, c, d and e is 1 or more. The upper limit of the total of a, b, c, d and e is not particularly limited, but is preferably 100 or less, more preferably 80 or less, further preferably 60 or less, and particularly preferably 40 or less.

Further, it is preferable that at least one of the structural unit (IV) and the structural unit (V) is contained in the polysiloxane structure. Therefore, the total of d and e is preferably an integer of 1 or more, more preferably an integer of 2 or more, and even more preferably an integer of 3 or more.

In the polysiloxane structure composed of the structural units described above, it is preferable that a to e satisfy (d + e) / (a + b + c + d + e) ≧ 0.7. This formula shows that the ratio of the T1 and T2 structures to the D1, D2, T1, T2 and T3 structures constituting the polysiloxane is 0.7 or more. Here, the D1 structure and the D2 structure are siloxanes formed by forming a siloxane bond with one or two alkoxy groups among the two alkoxy groups bonded to the silicon atom contained in the organodialkoxysilane, respectively. The unit (constituent unit), T1, T2, and T3 structure, respectively, refers to one, two, or three alkoxy groups among the three alkoxy groups bonded to the silicon atom contained in the organotrialkoxysilane. A siloxane unit (constituent unit) formed by forming a siloxane bond in a group. The large number of T1 and T2 structures means that the polysiloxane has many silanol groups in the presence of water, and the water solubility of the polysiloxane is high. The abundance ratio of each component D1, D2, T1, T2, T3 structure can be calculated from the peak area ratio derived from the D1, D2, T1, T2, and T3 structures using ²⁹ Si-NMR.

Furthermore, the silanol group content, which greatly affects the water solubility, can be calculated by using the following method. First, using ¹ H-NMR, a calibration curve of the amount of methoxysilyl group was prepared from methyltrimethoxysilane using tetraethoxysilane as an internal standard, and the content of the methoxysilyl group in the glycidyl group-containing modified polysiloxane resin was determined. Quantify. Next, the silanol group content can be calculated by subtracting the methoxysilyl group amount from the molar ratio of the D1, D2, T1, T2, and T3 structures and the measurement result of the silicon content described later. The silanol group content is preferably 3% by weight or more, more preferably 5% by weight or more, and particularly preferably 10% by weight or more. If the silanol group is less than 3% by weight, the water solubility may be insufficient and the silanol group may not be dissolved in water.

The order of linking the five types of structural units in the polysiloxane resin is not limited. Further, when b, c and d of the structural units (II), (III) and (IV) each represent an integer of 2 or more, the same structural unit existing in a plurality may be continuous with each other. Further, another structural unit may be sandwiched between them. That is, the type of copolymerization may be either block copolymerization or random copolymerization.

In each structural unit, there is a place where the description of the structure in which the oxygen atom bonded to the silicon atom is further bonded is omitted, but in this place, another siloxane unit (constituent unit) is bonded to the oxygen atom. It means that you are doing it. Further, a bond may be formed between the two locations contained in one molecule represented by the structural units (I) to (V) to form a cyclized polysiloxane structure in the molecule. Further, when the structural unit (I) or the structural unit (V) is 0, it also means that another structural unit is bonded to the end of the polysiloxane structure, and the structural unit (I) is at the end. )-(V) may be bonded to two units of the structure represented by (V), or a cyclized structure may be formed in the molecule.

The details of the substituents ^R1 and ^R2 contained in the structural units (I) to (V) will be described below, but when a plurality of the substituents R1 and R2 are present, the substituents may be the same. , A plurality of types may coexist within the range satisfying the following definitions.

R ¹ represents a hydrogen atom, a methyl group, an ethyl group or a propyl group.

R ² represents a substituted or unsubstituted vinyl group, a phenyl group or a cyclic or acyclic alkyl group having 1 to 8 carbon atoms. When the polysiloxane resin contains 1 or more R ² , at least 1 or more of the R ² has a glycidyl group.

From the viewpoint of transparency, solvent resistance and water resistance of the coating film, ^R2 is preferably a group having 6 or less carbon atoms, and more preferably 3 or less carbon atoms. When the end of the alkyl group is substituted with any organic functional group such as glycidyloxypropyl group, epoxycyclohexyl group, (meth) acryloyloxy group, mercapto group or styryl group, R ² is due to the reactivity of the organic functional group. 3 is preferable, and when it is not substituted with an organic functional group, it is particularly preferable from the viewpoint that the methyl group having 1 carbon does not dissipate the cross-linking reaction when forming a cured coating film.

When R ² represents a 3-glycidyloxypropyl group, the content of the glycidyl group is preferably 12% by weight or more based on the total amount of the glycidyl group-containing modified polysiloxane resin. The content of the glycidyl group is more preferably 20% by weight or more, and particularly preferably 25% by weight or more. In the above range, the hydrophilicity of the glycidyl group-containing modified polysiloxane resin can be enhanced, the curing reaction proceeds sufficiently, and a cured film having excellent hardness, water resistance, and weather resistance can be formed.

The content of glycidyl group refers to the content of epoxy group in the present invention, and the weight of the epoxy ring contained in 3-glycidyloxypropyl group which is ^R2 with respect to the total solid content of the modified polysiloxane resin containing glycidyl group. It means a ratio and is determined by the following method. First, the epoxy equivalent with respect to the total amount of the resin composition is measured using a general-purpose automatic titrator GT-200 (Mitsubishi Chemical Analytech). For example, when the measurement result of the epoxy equivalent is 430, it means that the epoxy group is contained in 43/430 × 100 = 10% by weight because the molecular weight of the epoxy group is 43.

When R ² represents a methyl group, the content of the methyl group is preferably 2% by weight or more and 12% by weight or less based on the total amount of the glycidyl group-containing modified polysiloxane resin. The content of the methyl group is more preferably 4% by weight or more and 10% by weight or less, and particularly preferably 5% by weight or more and 7% by weight or less. In the above range, the silicon content in the glycidyl group-containing modified polysiloxane resin can be increased, and the steric hindrance caused by R ² is reduced, so that the curing reaction proceeds sufficiently, and the weather resistance, water resistance, and solvent resistance are reduced. It is possible to form an excellent cured coating film.

The content of the methyl group means the weight ratio of the methyl group as ^R2 to the total solid content of the glycidyl group-containing modified polysiloxane resin, and is determined by the following method. First, using ¹ H-NMR, a calibration curve of the methyl group amount is prepared from methyltrimethoxysilane using tetraethoxysilane as an internal standard, and the methyl group content in the glycidyl group-containing modified polysiloxane resin is quantified. do. Since the molecular weight of methyltrimethoxysilane is 136.2, methyltrimethoxysilane contains 15 / 136.2 = 11.0% by weight of the methyl group, and this value and tetraethoxysilane are used as internal standards. The content of the methyl group with respect to the total solid content of the glycidyl group-containing modified polysiloxane resin can be calculated from the calibration line. However, when the glycidyl group-containing modified polysiloxane resin contains a solvent, the content of the methyl group means the ratio to the non-volatile content containing no solvent.

In the polysiloxane structure composed of the siloxane unit (constituent unit) described above, the silicon content is preferably 15% by weight or more and 40% by weight or less with respect to the total solid content of the glycidyl group-containing modified polysiloxane resin. .. The silicon content is preferably 16% by weight or more and 30% by weight or less, and more preferably 19% by weight or more and 25% by weight or less. By using the glycidyl group-containing modified polysiloxane resin having a high silicon content as described above, the reaction points at the time of forming the cured film are increased, so that the crosslink density in the cured film is increased, and the hardness of the cured film formed is increased. Water resistance can be increased. Further, a high silicon content means that there are many parts in the cured film that are not easily torn or deteriorated by heat and / or light, that is, the cured film tends to have high weather resistance.

The silicon content means the weight ratio of silicon atoms to the total solid content of the glycidyl group-containing modified polysiloxane resin, and is determined by the following method. First, ²⁹ Si-NMR is used to quantify the molar ratios of the D1, D2, T1, T2, and T3 structures contained in the glycidyl group-containing modified polysiloxane resin.

When the glycidyl group-containing modified polysiloxane resin contains a T3 structure, ²⁹ Si-NMR is used in advance, and tetraethylsilane is used as an internal standard, and [2- (3,4-epoxycyclohexyl) ethyl] -heptaisobutylcil is used. Based on the calibration curve of the silicon content derived from the T3 structure prepared using sesquioxane, the silicon content derived from the T3 structure is calculated with respect to the total solid content of the glycidyl group-containing modified polysiloxane resin. From this value and the molar ratio of each structure, the silicon content (total of the silicon contents derived from the D1, D2, T1, T2 and T3 structures) with respect to the total solid content of the glycidyl group-containing modified polysiloxane resin can be obtained.

²⁹ If the peak of the T3 structure is not confirmed by Si-NMR and it is judged that the glycidyl group-containing modified polysiloxane resin does not contain the T3 structure, 1,1,3,3-tetramethyl-1,3- Calibration line for D1 structure prepared using diethoxypropanedisiloxane, calibration line for D2 structure prepared using octamethylcyclotetrasiloxane, 1,1,3,3-tetramethoxy-1,3-dimethyl Calculate the silicon content of each structure based on the calibration line for the T1 structure prepared using propanedisiloxane and the calibration line for the T2 structure prepared using methyl (bistrimethylsilyloxy) monomethoxysilane. Therefore, the silicon content of the glycidyl group-containing modified polysiloxane resin with respect to the total solid content can be obtained from the molar ratio of each structure. However, the silicon content means the ratio of the glycidyl group-containing modified polysiloxane resin to the solid content containing no solvent when the resin contains a solvent.

The curable resin composition of the present invention is set to have a water content of 30% by weight or more and an alcohol content of 10% by weight or less with respect to the total solid content of the glycidyl group-containing modified polysiloxane resin. The curable resin composition can be a water-based paint that is not designated as a dangerous substance because the vapor pressure decreases due to the high water content and the small amount of solvent, and the flash point rises or disappears. You can. The lower the solvent content, the more preferable, specifically, 8% by weight or less is preferable, 5% by weight or less is more preferable, and 1% by weight or less is particularly preferable.

When the curable resin composition of the present invention is used as a water-based paint, it is preferable to contain a small amount of solvent from the viewpoint of wettability to a substrate, and an appropriate amount is contained in the range of 10% by weight or less. May be good.

In the present application, the method for measuring the water content of the composition is not particularly limited, and the water content can be measured using a known moisture meter. The method for measuring the solvent content is not particularly limited, and the solvent content can be measured by using, for example, gas chromatography.

(Organoalkoxysilane)
Examples of the organoalkoxysilane used in the glycidyl group-containing modified polysiloxane resin contained in the curable resin composition include organotrialkoxysilane represented by the general formula (VI) and organoloxysilane represented by the general formula (VII). It is preferable to use at least one of the dialkoxysilanes. It is more preferable to use at least the organotrialkoxysilane represented by the general formula (VI), and if necessary, to use the organodialkoxysilane represented by the general formula (VII) in combination.

In the formulas (VI) and (VII), the definitions and specific examples of the substituents ^R1 and ^R2 are the same as those described above for the structural units (I) to (V).

Specific examples of the organotrialkoxysilane are not particularly limited, but are, for example, methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane, and propyl. Examples thereof include trimethoxysilane, propyltriethoxysilane, propyltriisopropoxysilane, butyltrimethoxysilane, butyltriethoxysilane, butyltriisopropoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, hexyltriisopropoxysilane and the like. .. One of these may be used, or two or more thereof may be used in combination.

Specific examples of the organodialkoxysilane are not particularly limited, but for example, dimethyldimethoxysilane, dimethyldiethoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, and vinylmethyldimethoxysilane. , Vinylmethyldiethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexylmethyldiethoxysilane and the like. One of these may be used, or two or more thereof may be used in combination.

In the organoalkoxysilane, the alkoxy group bonded to the silicon atom (OR ¹ in the formulas (VI) and (VII)) is preferably an alkoxy group having 1 to 3 carbon atoms, from the viewpoint that hydrolysis and dehydration condensation reaction can easily proceed. , A methoxy group or an ethoxy group is preferable, and a methoxy group is most preferable.

In the organoalkoxysilane, the organic group bonded to the silicon atom (R ² in the formulas (VI) and (VII)) is an organic substituted with a vinyl group, a phenyl group, an alkyl group having 1 to 6 carbon atoms or a glycidyloxy group. Groups are preferred. From the viewpoint of increasing the water solubility of the curable resin composition, an organic group substituted with a glycidyloxy group is more preferable. From the viewpoint that the steric hindrance is small, the curable resin composition of the present invention has excellent curability, and the water solubility is not impaired, an unsubstituted methyl group and an ethyl group are preferable, and a methyl group is particularly preferable.

From the viewpoint of availability and cost, 3-glycidyloxypropyltrimethoxysilane and methyltrimethoxysilane are most preferable as the organoalkoxysilane.

Further, the organic group bonded to the silicon atom in the organoalkoxysilane is not particularly limited, but may have a functional group. By having a functional group, it is possible to give the curable resin composition of the present invention a curing form based on the functional group in addition to a curing form based on the hydrolysis and dehydration condensation reaction of the hydrolyzable silyl group. Become. By incorporating such a curing form using a functional group, it may be possible to suppress the shrinkage of the coating film due to the hydrolysis of the hydrolyzable silyl group and the dehydration condensation reaction. Such functional groups are not particularly limited, and examples thereof include a glycidyloxy group, an epoxycyclohexyl group, a (meth) acryloyloxy group, an amino group, an aminoethylamino group, an anirino group, a mercapto group and a styryl group. It may have only one kind of these functional groups, or it may have a plurality of kinds.

Examples of the organoalkoxysilane having such a functional group include 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, and 8-glycidyloxyoctyltrimethoxysilane. , 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3- (meth) acryloyloxypropyltrimethoxysilane, 3- (meth) acryloyloxypropylmethyldimethoxysilane, 3- (meth) acryloyloxypropyltriethoxy Silane, 3- (meth) acryloyloxypropylmethyldiethoxysilane, (meth) acryloyloxyoctyltrimethoxysilane, (meth) acryloyloxyoctyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane , 3-Aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, N- (2-aminoethyl) ) -3-Aminopropylmedyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltriethoxysilane and the like.

Among the above descriptions, the glycidyl group-containing modified polysiloxane resin contained in the curable resin composition includes only 3-glycidyloxypropyltrimethoxysilane (single condensation), or 3-glycidyloxypropyltrimethoxysilane and methyl. More preferably, it is synthesized by cocondensation with one or more silane compounds selected from four kinds of trimethoxysilane, vinyltrimethoxysilane, dimethyldimethoxysilane, and 3-glycidyloxypropylmethyldimethoxysilane.

(Manufacturing of curable resin composition)
The method for producing the curable resin composition of the present invention is not particularly limited, but an example will be described below.

The curable resin composition of the present invention contains a glycidyl group-containing modified polysiloxane resin, and when the curable resin composition is produced, an organoalkoxysilane containing a silane coupling agent having a glycidyl group is contained in water. It comprises a step of forming the glycidyl group-containing modified polysiloxane resin by subjecting it to a hydrolysis and dehydration condensation reaction in the reaction solution. The glycidyl group-containing modified polysiloxane resin contains at least one of the structural units (I) to (V). Further, the curable resin composition has a water content of 30% by weight or more and an alcohol content of 10% by weight or less with respect to the total solid content of the glycidyl group-containing modified polysiloxane resin by using vacuum distillation or the like. Adjust and use as follows. Further, the glycidyl group-containing modified polysiloxane resin preferably contains 12% by weight or more of the glycidyl group with respect to the total solid content.

(Manufacturing conditions)
The production method of the present invention comprises a step of hydrolyzing and dehydrating and condensing an organoalkoxysilane in a reaction solution containing water, and a to e in the structural units (I) to (V) are (d + e) /. Under the condition that (a + b + c + d + e) ≧ 0.7, the step of removing the generated alcohol and the step of diluting with water are carried out, and the water content is 30% by weight or more and the alcohol content is 10% by weight or less based on the total amount of the composition. Including the process. Either the alcohol removal step or the water dilution step may be performed first. If the alcohol removal step is carried out first, the required reaction vessel can be small because the concentration can always be high. If the dilution step with water is carried out first, the resin concentration increases and the possibility of gelation can be reduced.

Generally, it is difficult to stop the hydrolysis and dehydration condensation reaction of a silane compound in the middle of the reaction. For example, in the case of dilution using a solvent, the dehydration condensation reaction proceeds even if it is slow, and eventually (d + e) / (a + b + c + d + e) <0.7. On the other hand, in the case of dilution using water, for example, the equilibrium of the hydrolysis and dehydration condensation reaction shifts to the hydrolysis side due to the presence of water, so that the progress of the dehydration condensation reaction is suppressed.

Further, depending on the composition of the organoalkoxysilane, for example, the content of methyltrimethoxysilane is high in the organoalkoxysilane, the condensation reaction may proceed, that is, the curing reaction may proceed and the water solubility may not be exhibited. From this point of view, in order to increase the water solubility of the obtained polysiloxane, the content of 3-glycidyloxypropyltrimethoxysilane with respect to the total amount of the constituents of the organoalkoxysilane is preferably 40% by weight or more, more preferably 70% by weight or more. , 85% by weight is particularly preferable. If the content of 3-glycidyloxypropyltrimethoxysilane is less than 20% by weight, it cannot be diluted with water, and if it is 20% by weight or more and less than 40% by weight, it can be diluted with water, but the storage stability is insufficient. There is a concern that precipitation may occur or gelation may occur over time.

The amount of water used in the hydrolysis and dehydration condensation steps of the present invention shall be 40 mol% or more and 200 mol% or less with respect to 100% of the total number of moles of alkoxy groups bonded to silicon atoms contained in organoalkoxysilane. Is more preferable, 50 mol% or more and 100 mol% or less is more preferable, and 60 mol% or more and 80 mol% or less is particularly preferable. If the amount of water used is too small, the reaction of organoalkoxysilane does not proceed sufficiently, and a coating film with good transparency cannot be obtained, or unreacted organoalkoxysilane volatilizes together when removing alcohol. May be done. On the contrary, if the amount of water used is too large, there is a concern that the step of removing the generated alcohol and the step of diluting with water cannot be carried out under the condition that the general formula (d + e) / (a + b + c + d + e) <0.7 is satisfied. ..

Although it is not always necessary to use a catalyst in the hydrolysis and dehydration condensation steps of the present invention, it is preferable to add an acidic catalyst for the purpose of facilitating the satisfaction of (d + e) / (a + b + c + d + e) <0.7. The acidic catalyst has an effect of particularly accelerating hydrolysis in the hydrolysis and dehydration condensation reaction of the silane compound. On the other hand, basic catalysts and metal catalysts have a large effect of promoting the dehydration condensation reaction, and easily lead to a D2 structure or a T3 structure (d + e) / (a + b + c + d + e) <0.7, and remove the generated alcohol. It is difficult to carry out the process and the diluting process with water.

As the acidic catalyst, an organic acid is preferable, and a phosphoric acid ester or a carboxylic acid is more preferable, because of compatibility with an organoalkoxysilane or an organic solvent. Specific examples of organic acids include ethyl acid phosphate, butyl acid phosphate, dibutylpyrophosphate, butoxyethyl acid phosphate, 2-ethylhexyl acid phosphate, isotridecyl acid phosphate, dibutyl phosphate, bis (2-ethylhexyl) phosphate, and formic acid. Examples thereof include acetic acid, formic acid and isofatty acid. The amount of the catalyst added can be adjusted as appropriate, but may be, for example, about 50 ppm or more and 3% by weight or less with respect to organoalkoxysilane. Although the reaction time can be shortened by adding a large amount of catalyst, the catalyst remaining in the coating film may reduce its water resistance. Further, after the reaction is completed, the resin composition of the present invention may be gelled by the action of a catalyst. Therefore, it is preferable that the amount of the catalyst used is small within the range in which the effect of shortening the reaction time by the catalyst is achieved.

The temperature of the reaction solution when carrying out the hydrolysis and dehydration condensation steps of the present invention can be appropriately set by those skilled in the art, but for example, it is preferable to heat the reaction solution to a range of 50 ° C. or higher and 150 ° C. or lower. The reaction time can be appropriately set by those skilled in the art, but may be, for example, about 10 minutes or more and 48 hours or less.

The alcohol removing step of the present invention can be carried out by subjecting the reaction solution after the hydrolysis and dehydration condensation steps to vacuum distillation to distill off the alcohol. The conditions for vacuum distillation can be appropriately set by those skilled in the art.

(Other ingredients)
The curable resin composition of the present invention may contain other resins, metal oxide particles, solvents and the like as components other than the glycidyl group-containing modified polysiloxane resin.

Silica particles are preferable as those that can be blended without impairing curability, hardness, and weather resistance. The silica particles preferably have a silanol group on the particle surface. The silanol group can react with ^one OR group in the structural unit (I), such as the silanol group and the alkoxysilyl group contained in the glycidyloxypropyl-modified posiloxane resin of the present invention. Since it is incorporated into the cured coating film via a covalent bond, the hardness and weather resistance are not impaired, and the hardness of the cured coating film is improved by the hardness of the silica particles depending on the blending amount. The blending amount is preferably 1% by weight or more and 30% by weight or less, more preferably 5% by weight or more and 25% by weight or less, and 10% by weight, based on the resin content excluding volatile components such as solvent and water in the resin composition. More than 20% by weight is particularly preferable. If it is more than 30% by weight, a large amount of silanol groups not used in the curing reaction may remain in the cured coating film, which may reduce the water resistance. Further, if it is more than 60% by weight, the ratio to the film forming component is too high, and sufficient film forming property may not be obtained, resulting in poor appearance. On the other hand, if it is less than 1% by weight, the coating film performance is not adversely affected, but the hardness and weather resistance obtained from the silica particles may not be positively affected.

When a condensation catalyst is used in synthesizing a glycidyl group-containing modified polysiloxane resin in the present invention, the curable resin composition of the present invention usually also contains the condensation catalyst.

Further, the curable resin composition of the present invention may contain a resin component not derived from the production method in addition to the above-mentioned glycidyl group-containing modified polysiloxane resin. As such a resin, water-soluble, water-dispersed, and emulsion-type resins of (meth) acrylic resin, vinyl chloride, and epoxy resin are preferable. Further, since weather resistance is often required when polysiloxane is used, a (meth) acrylic resin is preferable among the above resin groups, and a (meth) acrylic resin having a hydrolyzable silyl group in the side chain is further preferable. .. Further, although it is not a resin component, organoalkoxysilane itself may be contained.

The curable resin composition of the present invention may appropriately contain a known resin other than those described above.

The curable resin composition of the present invention may contain a solvent other than water in an amount of 10% by weight or less based on the curable resin composition. The solvent is not particularly limited, and a solvent suitable for dissolving or dispersing a glycidyl group-containing modified polysiloxane resin is preferable, and considering the human influence during painting, it is more volatile than water. A lower solvent is more preferred. Examples of such a solvent include dientylene glycol and propylene glycol monomethyl ether.

(Coating liquid)
The curable resin composition of the present invention can be a curable resin composition for paints, that is, a coating liquid. When making a coating liquid, pigments, plasticizers, dispersants, anti-settling agents, antifungal agents, preservatives, anti-skin agents, desiccants, anti-dripping agents, matting agents, anti-static agents, conductive agents, flame retardants And the like, known additives for paints can be appropriately blended. Since the curable resin composition of the present invention has excellent hardness, weather resistance, and high transparency, it is preferable to use it as a coating liquid for a clear coating film containing no pigment.

The curable resin composition or coating liquid of the present invention contains a curing agent because the curing reaction of the coating film is promoted in the presence of the curing agent and the working time at the time of forming the coating film can be shortened. Alternatively, it is preferably a two-component composition or coating solution containing the curing agent in another package.

As the curing agent, a known curing agent as a curing agent used for a curable composition utilizing a hydrolysis reaction and a dehydration condensation reaction of an alkoxysilyl group can be appropriately used. Specifically, as the curing agent, the above-mentioned condensation catalyst can be used, and an organic tin compound, a titanium chelate compound, an aluminum chelate compound, an organic amine compound, a phosphoric acid ester compound, and the like can be used.

Specific examples of the organic tin compound include dioctyl tin bis (2-ethylhexyl malate), dioctyl tin oxide or a condensate of dibutyl tin oxide and silicate, dibutyl tin dioctate, dibutyl tin dilaurate, dibutyl tin distearate, and dibutyl tin diacetyl. Acetonate, dibutyl tin bis (ethyl malate), dibutyl tin bis (butyl malate), dibutyl tin bis (2-ethylhexyl malate), dibutyl tin bis (oleyl malate), stanas octoate, tin stearate, di-n- Examples include butyltin laurate oxide. Specific examples of the organotin compound having an S atom in the molecule include dibutyltin bisisononyl-3-mercaptopropionate, dioctyltin bisisononyl-3-mercaptopropionate, and octylbutyltin bisisononyl-3-mercaptopropio. Nate, dibutyltin bisisooctylthioglucolate, dioctyltin bisisooctylthioglucolate, octylbutyltin bisisooctylthioglucolate and the like can be mentioned.

Specific examples of the titanium chelate compound include titanium acetylacetonate, titaniumtetraacetylacetonate, titaniumethylacetoacetate, titanium phosphate compound, titaniumoctylene glycolate, titaniumethylacetoacetate and the like.

Specific examples of the aluminum chelate compound include ethyl acetoacetate aluminum diisopropyrate, aluminum tris (acetyl acetate), aluminum tris (ethyl acetoacetate), aluminum monoacetyl acetonate bis (ethyl acetoacetate), and alkyl acetyl acetate aluminum diisopropi. The rate etc. can be mentioned.

Specific examples of the organic amine compound include triethylamine, triethylenediamine, trimethylamine, tetramethylenediamine, N-methylmorpholine, N-ethylmorpholine, N, N'-diethyl-2-methylpiperazine, laurylamine, dimethyllaurylamine and the like. Can be mentioned.

As the phosphoric acid ester compound, an acidic phosphoric acid ester compound is preferable, and specific examples thereof include ethyl acid phosphate, butyl acid phosphate, dibutyl phosphate, butoxyethyl acid phosphate, 2-ethylhexyl acid phosphate, and ethylene glycol acid. Examples thereof include phosphate, dibutyl phosphate, bis (2-ethylhexyl) phosphate and the like.

Since the present invention contains a 3-glycidyloxypropyl group, among the above-mentioned cured products, those that cure the epoxy group are more preferable. From this viewpoint, titanium chelate compounds, aluminum chelate compounds, and organic amine compounds are particularly preferable.

The amount of the curing agent used can be appropriately adjusted according to the curing temperature and the curing time, but for example, it is preferably about 1 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the glycidyl group-containing modified polysiloxane resin. 2, 2 parts by weight or more and 5 parts by weight or less are more preferable.

The curable resin composition of the present invention can be applied to a substrate and cured to form a coating film. The conditions for coating and curing are not particularly limited, but it is preferable to use a heat source to promote evaporation of the solvent during curing.

The thickness of the coating film to be formed is not particularly limited, but in the present invention, the thickness after drying is preferably 5 μm or more and 100 μm or less. If the thickness is thinner than 5 μm, the water resistance and moisture resistance of the coating film may be insufficient. If the thickness exceeds 100 μm, cracks may occur due to curing shrinkage during formation of the coating film. It is more preferably 10 μm or more and 60 μm or less, and further preferably 20 μm or more and 40 μm or less.

Further, the coating film formed by the present invention has extremely high transparency, and the haze value is preferably 0.3 or less, more preferably 0.2 or less, and 0.1 or less. It is more preferable to have.

The base material to which the curable resin composition of the present invention can be applied is not particularly limited, and for example, glass, polycarbonate (PC), acrylic, acrylic silicon, acrylic urethane, acrylonitrile, butadiene, styrene (ABS), ABS / PC, etc. Various substrates such as polyethylene terephthalate (PET) can be used.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

The substances used in the examples and comparative examples are as follows.

Organoalkoxysilane Methyltrimethoxysilane (A-1630: Momentive Performance Materials Japan GK, molecular weight 136.2)
Methyltriethoxysilane (XIAMETER OFS-6370: Toray Dow Corning Co., Ltd., molecular weight 178.3)
Vinyltrimethoxysilane (A-171: manufactured by Momentive Performance Materials Japan GK, molecular weight 148.2)
Phenyltrimexisilane (Z-6124: Toray Dow Corning Co., Ltd., molecular weight 198.3)
3-Glysidyloxypropyltrimethoxysilane (A-187: manufactured by Momentive Performance Materials Japan GK, molecular weight 236.3).

Condensation catalyst dibutyl phthalate (manufactured by Johoku Chemical Industry Co., Ltd., molecular weight 210.2).
Triethylamine (Nacalai Tesque, Inc., molecular weight 101.2)
Dibutyl Tin Laurate (Nitto Kasei Co., Ltd. Molecular Weight 631.6)

Curing catalyst Polyethylenimine (Wako Pure Chemical Industries, Ltd., average molecular weight about 1800)
Dibutyl phthalate (manufactured by Johoku Chemical Industry Co., Ltd., molecular weight 210.2).

Examples, comparative examples and reference examples of the synthesis of the curable resin composition are shown below. The mixing ratio and the like are shown in Tables 1 and 2.

(Example 1: Synthesis of polysiloxane resin)
A-187 100.0 parts by weight and DBP 0.015 parts by weight were placed in a 300 mL volumetric 4-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and the mixture was stirred at room temperature for 10 minutes, and then pure water was added 13.7. A condensate was obtained by adding parts by weight and continuing stirring while raising the temperature in an oil bath heated to 90 ° C. for 4 hours. The obtained condensate was distilled under reduced pressure using an evaporator, methanol generated by the reaction was removed and concentrated, and then water was added and diluted to obtain a 45% concentration polysiloxane resin-containing aqueous solution.

(Example 2: Synthesis of polysiloxane resin)
A-187 100.0 parts by weight, A-1630 16.0 parts by weight, and DBP 0.016 parts by weight are placed in a 300 mL volumetric 4-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and stirred at room temperature for 10 minutes. Then, 17.5 parts by weight of pure water was added, and stirring was continued while raising the temperature in an oil bath heated to 90 ° C., and the mixture was reacted for 4 hours to obtain a condensate. The obtained condensate was distilled under reduced pressure using an evaporator, methanol generated by the reaction was removed and concentrated, and then water was added and diluted to obtain a 45% concentration polysiloxane resin-containing aqueous solution.

(Example 3: Synthesis of polysiloxane resin)
A-187 100.0 parts by weight, A-1630 36.1 parts by weight, and DBP 0.018 parts by weight are placed in a 300 mL volumetric four-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and stirred at room temperature for 10 minutes. Then, 17.5 parts by weight of pure water was added, and stirring was continued while raising the temperature in an oil bath heated to 90 ° C., and the mixture was reacted for 4 hours to obtain a condensate. The obtained condensate was distilled under reduced pressure using an evaporator, methanol generated by the reaction was removed and concentrated, and then water was added and diluted to obtain a 45% concentration polysiloxane resin-containing aqueous solution.

(Example 4: Synthesis of polysiloxane resin)
A-187 100.0 parts by weight, A-1630 61.9 parts by weight, and DBP 0.021 parts by weight are placed in a 300 mL volumetric 4-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and stirred at room temperature for 10 minutes. Then, 17.5 parts by weight of pure water was added, and stirring was continued while raising the temperature in an oil bath heated to 90 ° C., and the mixture was reacted for 4 hours to obtain a condensate. The obtained condensate was distilled under reduced pressure using an evaporator, methanol generated by the reaction was removed and concentrated, and then water was added and diluted to obtain a 45% concentration polysiloxane resin-containing aqueous solution.

(Example 5: Synthesis of polysiloxane resin)
A-187 100.0 parts by weight, A-1630 144.3 parts by weight, and DBP 0.029 parts by weight are placed in a 300 mL volumetric 4-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and stirred at room temperature for 10 minutes. Then, 17.5 parts by weight of pure water was added, and stirring was continued while raising the temperature in an oil bath heated to 90 ° C., and the mixture was reacted for 4 hours to obtain a condensate. The obtained condensate was distilled under reduced pressure using an evaporator, methanol generated by the reaction was removed and concentrated, and then water was added and diluted to obtain a 45% concentration polysiloxane resin-containing aqueous solution.

(Example 6: Synthesis of polysiloxane resin)
A-187 100.0 parts by weight, XIAMETER OFS-6370 13.1 parts by weight, DBP 0.016 parts by weight were placed in a 300 mL volumetric 4-necked flask equipped with a stirrer, a thermometer and a reflux condenser for 10 minutes at room temperature. After stirring, 17.5 parts by weight of pure water was added, and the mixture was continuously stirred while being heated in an oil bath heated to 90 ° C. and reacted for 4 hours to obtain a condensate. The obtained condensate was distilled under reduced pressure using an evaporator, methanol generated by the reaction was removed and concentrated, and then water was added and diluted to obtain a 45% concentration polysiloxane resin-containing aqueous solution.

(Example 7: Synthesis of polysiloxane resin)
A-187 100.0 parts by weight, A-171 14.5 parts by weight, and DBP 0.016 parts by weight are placed in a 300 mL volumetric four-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and stirred at room temperature for 10 minutes. Then, 17.5 parts by weight of pure water was added, and stirring was continued while raising the temperature in an oil bath heated to 90 ° C., and the mixture was reacted for 4 hours to obtain a condensate. The obtained condensate was distilled under reduced pressure using an evaporator, methanol generated by the reaction was removed and concentrated, and then water was added and diluted to obtain a 45% concentration polysiloxane resin-containing aqueous solution.

(Example 8: Synthesis of polysiloxane resin)
A-187 100.0 parts by weight, Z-6124 11.9 parts by weight, and DBP 0.016 parts by weight are placed in a 300 mL volumetric 4-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and stirred at room temperature for 10 minutes. Then, 17.5 parts by weight of pure water was added, and stirring was continued while raising the temperature in an oil bath heated to 90 ° C., and the mixture was reacted for 4 hours to obtain a condensate. The obtained condensate was distilled under reduced pressure using an evaporator, methanol generated by the reaction was removed and concentrated, and then water was added and diluted to obtain a 45% concentration polysiloxane resin-containing aqueous solution.

(Comparative Example 1: Synthesis of Polysiloxane Resin)
A-187 100.0 parts by weight, A-1630 16.0 parts by weight, and DBP 0.016 parts by weight are placed in a 300 mL volumetric 4-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and stirred at room temperature for 10 minutes. Then, 17.5 parts by weight of pure water was added, and the mixture was continuously stirred while raising the temperature in an oil bath heated to 90 ° C., and reacted for 36 hours to obtain a condensate. The obtained condensate was distilled under reduced pressure using an evaporator to remove methanol generated by the reaction and concentrate.

(Comparative Example 2: Synthesis of Polysiloxane Resin)
A-187 100.0 parts by weight, A-1630 16.0 parts by weight, and triethylamine 0.0081 parts by weight were placed in a 300 mL volumetric 4-necked flask equipped with a stirrer, a thermometer, and a reflux condenser for 10 minutes at room temperature. After stirring, 17.5 parts by weight of pure water was added, and the mixture was continuously stirred while being heated in an oil bath heated to 90 ° C. and reacted for 4 hours to obtain a condensate. The obtained condensate was distilled under reduced pressure using an evaporator to remove methanol generated by the reaction and concentrate.

(Comparative Example 3: Synthesis of Polysiloxane Resin)
A-187 100.0 parts by weight, A-1630 16.0 parts by weight, and dibutyltin laurate 0.0081 parts by weight were placed in a 300 mL volumetric 4-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and at room temperature. The mixture was stirred for 10 minutes, then 17.5 parts by weight of pure water was added, and the mixture was continuously stirred while being heated in an oil bath heated to 90 ° C. and reacted for 4 hours to obtain a condensate. The obtained condensate was distilled under reduced pressure using an evaporator to remove methanol generated by the reaction and concentrate.

(Comparative Example 4: Synthesis of Polysiloxane Resin)
A-187 100.0 parts by weight, A-1630 336.8 parts by weight, DBP 0.049 parts by weight are placed in a 300 mL volumetric 4-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and stirred at room temperature for 10 minutes. Then, 17.5 parts by weight of pure water was added, and stirring was continued while raising the temperature in an oil bath heated to 90 ° C., and the mixture was reacted for 4 hours to obtain a condensate. The obtained condensate was distilled under reduced pressure using an evaporator, methanol generated by the reaction was removed and concentrated, and then water was added and diluted to obtain a 45% concentration polysiloxane resin-containing aqueous solution.

(Comparative Example 5: Synthesis of Polysiloxane Resin)
A-187 100.0 parts by weight, A-1630 1299.1 parts by weight, and DBP 0.147 parts by weight are placed in a 300 mL volumetric 4-necked flask equipped with a stirrer, a thermometer and a reflux condenser, and stirred at room temperature for 10 minutes. Then, 17.5 parts by weight of pure water was added, and stirring was continued while raising the temperature in an oil bath heated to 90 ° C., and the mixture was reacted for 4 hours to obtain a condensate. The obtained condensate was distilled under reduced pressure using an evaporator, methanol generated by the reaction was removed and concentrated, and then water was added and diluted to obtain a 45% concentration polysiloxane resin-containing aqueous solution.

(Comparative Example 6: Synthesis of Polysiloxane Resin)
A 300 mL volume 4 flask equipped with a stirrer, a thermometer and a reflux condenser was charged with 100.0 parts by weight of A-1630 and 0.010 parts by weight of DBP, stirred at room temperature for 10 minutes, and then pure water was added 17.5. A condensate was obtained by adding parts by weight and continuing stirring while raising the temperature in an oil bath heated to 90 ° C. for 4 hours. The obtained condensate was distilled under reduced pressure using an evaporator, methanol generated by the reaction was removed and concentrated, and then water was added and diluted to obtain a 45% concentration polysiloxane resin-containing aqueous solution.

(Reaction time)
In each Example and Comparative Example, the reaction time was defined as the time during which the organoalkoxysilane, the condensation catalyst, and water were mixed at room temperature and then the mixture was heated in an oil bath heated to 80 ° C.

(Reference example 1: Synthesis of (meth) acrylic resin)
In a 300 mL volumetric 4-necked flask equipped with a stirrer, thermometer, reflux condenser, nitrogen gas introduction tube and dropping funnel, 35.8 parts by weight of iPA was charged according to the formulation shown in Table 2 and 90 while introducing nitrogen gas. After heating to ° C, a mixture of 2.0 parts by weight of A-174, 40.0 parts by weight of BA, 48.3 parts by weight of MMA, 10.0 parts by weight of AA, and 7.22 parts by weight of V59 was added to the dropping funnel for 3 hours. It was dropped at a constant velocity. Next, a mixed solution of 0.36 parts by weight of V59 and 10.0 parts by weight of iPA was added dropwise at a constant velocity over 1 hour. Then, the mixture was subsequently stirred at 90 ° C. for 3 hours to synthesize a (meth) acrylic resin having a trimethoxysilyl group and a carboxyl group in the side chain. The weight average molecular weight of the obtained resin was 7300.

Various evaluation methods are shown below. The results of each evaluation are also shown in Table 1 or Table 3.

(Calculation of various component contents)
In Examples 1 to 8 and Comparative Examples 1 to 6, the calculated value of methanol removed by distillation was 90%. The ratio of T1 and T2 structures ((d + e) / (a + b + c + d + e)), the content of glycidyl group and silicon in the obtained polysiloxane resin are shown in Table 1. Each calculation method is shown below.

(Calculation of siloxane unit abundance ratio)
The abundance ratio of siloxane units in the curable resin composition was calculated from the peak area ratios derived from the D1, D2, T1, T2, and T3 structures using ²⁹ Si-NMR. Peaks derived from the D1, D2, T1, T2, and T3 structures show peaks at different positions (chemical shifts), and specifically, for example, when they have at least one of the structural units (I) to (V). , D1, D2, T1, T2, and T3 structures can be confirmed in the vicinity of -10 ppm to -18 ppm, -20 ppm to -25 ppm, -45 ppm to -52 ppm, -54 ppm to -62 ppm, and -64 to -70 ppm, respectively. By the above method, the abundance ratio of the siloxane unit in the synthesized curable resin composition was confirmed.

(Calculation of glycidyl group content)
The epoxy equivalent with respect to the total amount of the resin composition was measured using a general-purpose automatic titrator GT-200 (Mitsubishi Chemical Analytec). For example, when the measurement result of the epoxy equivalent is 430, it means that the epoxy group is contained in 43/430 × 100 = 10% by weight because the molecular weight of the epoxy group is 43.

(Calculation of silicon content in siloxane unit)
First, using ²⁹ Si-NMR, the molar ratios of the D1, D2, T1, T2, and T3 structures contained in the glycidyl group-containing modified polysiloxane resin are quantified using tetraethylsilane as an internal standard. Next, the silicon content derived from the T3 structure contained in the glycidyl group-containing modified polysiloxane resin is calculated from the molar ratio of the T3 structure and the calibration curve. The calibration curve was prepared in advance using ²⁹ Si-NMR, using tetraethylsilane as an internal standard, and using [2- (3,4-epoxycyclohexyl) ethyl] -heptaisobutylsilsesquioxane. The total amount of silicon contained in the resin composition was calculated from the obtained silicon content derived from the T3 structure and the molar ratio of the initially obtained D1, D2, T1, T2, and T3 structures. For example, when the molar ratio of the T1, T2, and T3 structures determined by ²⁹ Si-NMR is 1: 2: 3, and the silicon content derived from the T3 structure is calculated to be 3% by weight from the calibration curve. The silicon feed rate contained in this resin composition can be calculated to be 6% by weight.

(Calculation of methyl group content directly linked to silicon)
¹ Using 1 H-NMR, a calibration curve of the methyl group amount is prepared from methyltrimethoxysilane using tetraethoxysilane as an internal standard, and the methyl group content in the glycidyl group-containing modified polysiloxane resin is quantified. Since the molecular weight of methyltrimethoxysilane is 136.2, methyltrimethoxysilane contains 15 / 136.2 = 11.0% by weight of the methyl group, and this value and tetraethoxysilane are used as internal standards. The content of the methyl group with respect to the total solid content of the glycidyl group-containing modified polysiloxane resin was calculated from the calibration line.

(Water soluble)
When the curable resin composition is dissolved in pure water at 25 ° C. by 40% by weight under 1 atm, the curable resin composition is made water-soluble, and in other cases, it is made water-insoluble. , Described in the table.

(Storage stability 1 (gelation))
A glycidyl group-containing modified polysiloxane resin-containing aqueous solution adjusted to have a non-volatile content of 45% is sealed in a glass bottle and allowed to stand in a hot air dryer heated to 25 ° C. The time when the fluidity could not be confirmed was set as the gel point, and the time was described in the table.

(Storage stability 2 (precipitation))
A glycidyl group-containing modified polysiloxane resin-containing aqueous solution adjusted to a non-volatile content of 45% was placed in a hot air dryer heated to 25 ° C. in a sealed state in a glass bottle, and a white precipitate was deposited at the bottom of the container by 1 mm or more. The time point was set as the precipitation point, and the time was described in the table.

(Preparation of coating liquid)
A curing catalyst and water for dilution were added to the obtained curable resin composition and stirred until uniform to obtain a coating liquid. The compounding ratio of each component is as described in Examples, Comparative Examples and Reference Examples ([Table 1] and [Table 2]). The blending amount shown in each table is based on the weight of the active ingredient, and the resin aqueous solution having a resin content of 45% obtained in each Example, Comparative Example and Reference Example is actually blended. Therefore, the blending amount of the coating liquid is a value obtained by dividing the blending amount of the resin described in each table by 45%.

(Preparation of evaluation film)
The coating liquid was applied onto a glass plate of 70 × 150 × 2 mm using a 6 mil applicator so that the dry film thickness was about 60 μm to form a coating film. After the coating film was cured under the conditions of 23 ° C. and 50% RH for 1 week, the transparency, hardness, weather resistance and water resistance of the coating film were evaluated based on the above-mentioned criteria.

(Transparency of coating film)
The transparency of the coating film formed under the evaluation film preparation conditions was determined by the haze value. To measure the haze value, a color and turbidity simultaneous measuring device COH400 (manufactured by Nippon Denshoku Industries Co., Ltd.) was used, and the value obtained by subtracting the haze value of the glass plate as the base material from the measured value was obtained. Listed in the table.

(hardness)
The hardness of the coating film formed under the evaluation film preparation conditions was measured with a Perzo pendulum hardness tester model 299/300 (manufactured by Ericssen).

(Weatherability)
An accelerated weather resistance test was carried out using a metal weather manufactured by Daipla Wintes Co., Ltd. As the test conditions, after irradiating the test plate at 63 ° C. and 50% RH for 6 hours, dark dew condensation was carried out at 30 ° C. and 98% RH for 2 hours as one cycle, and 25 cycles were continuously carried out. The evaluation was performed by the gloss retention rate calculated from the difference between the gloss value of the coating film surface immediately after formation and the gloss value of the coating film surface after the end of 25 cycles. The gloss value was measured using GM268 (manufactured by Minolta Co., Ltd.). The test plate is prepared by spraying an amount of the coating liquid having a dry film thickness of 10 micromillimeters to 15 micromillimeters onto a glass plate and curing the test plate under the conditions of 23 ° C. and 50% RH for one week. Made in. The side surface of the test plate was sealed with aluminum tape to prevent water from entering the interface between the coating film and the glass substrate (side surface of the test plate) and causing peeling or cracking.

(water resistant)
The coating film formed under the above evaluation film preparation conditions was immersed in warm water heated to 80 ° C. and held for 2 hours, and then the change in the coating film was visually confirmed and evaluated according to the following criteria. The side surface of the test plate was sealed with aluminum tape in order to prevent water from entering the interface between the coating film and the glass substrate (side surface of the test plate) and causing peeling or cracking.
A: When visually observed, there was no white turbidity or cracks in the coating film. B: When visually observed, there was no white turbidity or cracks in the coating film, but a clear glossiness (a phenomenon in which some or all of the gloss was lost) was observed. C: When visually observed, the coating film was cloudy and / or cracks were generated in the coating film.

(Results and discussion)
The glycidyl group-containing modified polysiloxane resins of Examples 1 to 8 were all water-soluble and had good storage stability. On the other hand, Comparative Examples 1 to 3 had insufficient water solubility and could not be diluted with water. Although Comparative Examples 4 to 6 were water-soluble, the storage stability was poor. From the above, it is considered that when the resin is synthesized using an acid catalyst in a relatively short time, the residual ratio of silanol is high and water solubility is observed. On the other hand, when a base catalyst or a tin catalyst was used, it is considered that the condensation of silanol proceeded and the remaining silanol decreased, so that the water did not become water-soluble. Further, even when an acid catalyst is used, it is considered that when the reaction time is long, the condensation of silanol proceeds and the remaining silanol is reduced, so that the water does not become water-soluble.

The results of confirming the film physical characteristics of Examples 1 to 8 are shown in Examples 9 to 16. Further, Reference Example 2 shows general film physical properties in which acrylic silicone and polysiloxane resin are used in combination. All of Examples 9 to 16 showed performance equal to or higher than that of the film properties of Reference Example 2. Examples 10 and 11 were good in terms of hardness, weather resistance, and water resistance, and Examples 12 and 13 were even better. From this, it is considered that the higher the silicon content, the better the hardness, weather resistance, and water resistance, and for alkoxysilane, methoxysilane, which has high reactivity, is better than ethoxysilane, which has low reactivity. Further, in R ² in the constituent units (I) to (V), the methyl group had the best hardness, weather resistance and water resistance. It is considered that this is because there are few steric hindrances and the cross-linking reaction of alkoxysilane is not inhibited.

Claims (6)

A curable resin composition containing a glycidyl group-containing modified polysiloxane resin.
The glycidyl group-containing modified polysiloxane resin contains at least one of the following structural units (I) to (V).
The composition ratio of the composition units (I) to (V) satisfies (d + e) / (a + b + c + d + e) ≧ 0.7.
The content of the glycidyl group with respect to the total solid content of the glycidyl group-containing modified polysiloxane resin is 12% by weight or more.
The curable resin composition contains 30% by weight or more of water and 10% by weight or less of alcohol with respect to 100% by weight of the total amount of the curable resin composition .
Curable resin composition.

In the formula, a to e indicate an integer of 0 or more, and d + e is 1 or more.
R ¹ represents a hydrogen atom, a methyl group, an ethyl group, or a propyl group.
R ² represents a substituted or unsubstituted vinyl group, a phenyl group or a cyclic or acyclic alkyl group having 1 to 8 carbon atoms, and has at least one or more glycidyl groups. R ² may be the same or different. The curable resin composition according to claim 1, wherein the content of silicon with respect to the total solid content of the glycidyl group-containing modified polysiloxane resin is 15% by weight or more. Select from 4 types of 3-glycidyloxypropyltrimethoxysilane single condensation, 3-glycidyloxypropyltrimethoxysilane, methyltrimethoxysilane, vinyltrimethoxysilane, dimethyldimethoxysilane, or 3-glycidyloxypropylmethyldimethoxysilane. The curable resin composition according to claim 1 or 2, which is synthesized by cocondensation with one or more silane compounds. The glycidyl group-containing modified polysiloxane resin contains R ² which is a methyl group in the structural units (I) to (V), and the content of the methyl group contained in the total amount of the glycidyl group-containing modified polysiloxane resin is The curable resin composition according to any one of claims 1 to 3, wherein the content is 2% by weight or more and 12% by weight or less. A coating liquid for a clear coating film containing the curable resin composition according to any one of claims 1 to 4. A method for producing a curable resin composition containing a glycidyl group-containing modified polysiloxane resin.
The glycidyl group-containing modified polysiloxane resin contains at least one of the following structural units (I) to (V).
The composition ratio of the composition units (I) to (V) satisfies (d + e) / (a + b + c + d + e) ≧ 0.7.
The glycidyl group-containing modified polysiloxane resin comprises a step of obtaining the glycidyl group-containing modified polysiloxane resin by hydrolyzing and dehydrating and condensing the silane compound using an acidic catalyst.
The curable resin composition has a step of setting the water content to 30% by weight or more with respect to 100% by weight of the total amount of the curable resin composition, and
A step of setting the alcohol content to 10% by weight or less with respect to 100% by weight of the total amount of the curable resin composition is included.
The production method, wherein the glycidyl group-containing modified polysiloxane resin contains 12% by weight or more of a glycidyl group with respect to the total amount of solid content.

In the formula, a to e indicate an integer of 0 or more, and d + e is 1 or more.
R ¹ represents a hydrogen atom, a methyl group, an ethyl group, or a propyl group.
R ² represents a substituted or unsubstituted vinyl group, a phenyl group or a cyclic or acyclic alkyl group having 1 to 8 carbon atoms, and has at least one or more glycidyl groups. R ² may be the same or different.