JPH10298252A - Curable composition and preparation thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a curable compsn. excellent in clarity by compounding a silica-based polycondensate obtd. by the hydrolysis and polycondensation of a silane compd. in the presence of colloidal silica having a specified particle size a polyfunctional (meth)acrylate, and a polymn. initiator. SOLUTION: A (meth)acryloyloxysilane compd. represented by formula I (R<1> is H or methyl; R<2> is 1-3C alkyl, etc.; R<3> is H or a 1-10C hydrocarbon group; and q is 1-6) is subjected to hydrolysis and polycondensation at 45-100 deg.C for 3-24 hr in the presence of colloidal silica having an average particle size of 1-100 nm to give a silica-based polycondensate. The objective compsn. contains this silica-based polycondensate, a polyfunctional (meth)acrylate comprising 100-50 wt.% di(meth)acrylate represented by formula II (R<4> is H or methyl; and m and n are each 1-5) and 0-50 wt.% alkanediol di(meth)acrylate and/or polyethylene glycol di(meth)acrylate, and a polymn. initiator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curable composition and a method for producing the same, and more particularly to a curable composition having good dispersibility of silica fine particles in a polyfunctional (meth) acrylate.
The present invention also relates to a curable composition having excellent transparency and the like and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, various industrial fields have been researching composite materials for improving performance by blending an organic substance with an inorganic substance to make a composite by utilizing both characteristics.
In such a composite material, the inorganic substance is uniformly dispersed by controlling the interface between the organic substance and the inorganic substance by a technique such as silane coupling treatment or grafting.

However, in order to obtain a composite material having excellent transparency, it is necessary to match the refractive index of an organic substance with that of an inorganic substance, and if it is intended to disperse inorganic fine particles on the order of nanometers (hereinafter referred to as nm), At present, it is difficult to put the inorganic fine particles into practical use because of the high-order aggregation of the inorganic fine particles, which significantly deteriorates the fluidity (thixotropic properties) and prevents the high filling.

As a technique for solving these problems, for example, JP-A-5-209027 discloses a curable composition excellent in transparency and rigidity in which colloidal silica is uniformly dispersed in methyl methacrylate using a silane compound. Things are listed. However, this silane compound is still insufficient in terms of the effect on organic matrices having different polarities (for example, polyfunctional (meth) acrylate having high hydrophobicity). That is, a curable composition having good dispersibility of colloidal silica and excellent transparency has not yet been obtained.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a curable composition in which colloidal silica of the order of nm is uniformly dispersed in a highly hydrophobic polyfunctional (meth) acrylate, and which is excellent in transparency and the like. It is an object of the present invention to provide a method for easily and satisfactorily producing the curable composition.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, by selecting a silane compound in consideration of polarity and reactivity and specifying reaction conditions, etc.
For the first time, it has been found that silica fine particles can be uniformly and satisfactorily dispersed in a polyfunctional (meth) acrylate having extremely high hydrophobicity, and a curable composition having excellent transparency and the like can be obtained.

That is, the above object can be achieved by the present invention described below.

In the presence of colloidal silica having an average particle size of 1 to 100 nm, the following general formula (I)

[0009]

Embedded image (Wherein, R ¹ is a hydrogen atom or a methyl group, R ² is an alkyl group or a phenyl group having 1 to ³ carbon atoms, R ³ is a hydrogen atom or a hydrocarbon residue having 1 to 10 carbon atoms, q is 1 to 6 And a silica-based condensation polymer (a) obtained by hydrolyzing and condensation-polymerizing a (meth) acryloyloxysilane compound (a-1) represented by the following general formula (II):

[0010]

Embedded image (Wherein, R ⁴ is a hydrogen atom or a methyl group, m and n each independently represent an integer of 1 to 5) di (meth) acrylate (b) 100 to 50 parts by weight, and
0 to 50 parts by weight of at least one di (meth) acrylate (c) selected from the group consisting of alkanediol di (meth) acrylate and polyethylene glycol di (meth) acrylate [provided that component (b) and component (c) Curable composition comprising: a polyfunctional (meth) acrylate (d) containing a poly (meth) acrylate (d) and a polymerization initiator (e).

This is a method for producing the curable composition of the present invention, which comprises conducting hydrolysis and condensation polymerization to obtain a silica-based condensation polymer (a) at a reaction temperature of 45 to 100 ° C. for a reaction time of 3 hours.
A method for producing a curable composition, which is carried out for up to 24 hours.

Generally, in order to obtain a silica-based polycondensate by modifying the surface of colloidal silica as spherical fine particles, an arbitrary silane compound is mixed in a colloidal silica dispersion and water in the system or fresh water is added. It is known that hydrolysis and polycondensation may be performed with added water. The present invention uses a specific silica-based condensation polymer (a) as this kind of silica-based condensation polymer, thereby preventing silica fine particles from aggregating in the polyfunctional (meth) acrylate (e). It is based on the effect of being able to disperse uniformly, with low viscosity, and well.

The silica-based condensation polymer (a) used in the present invention
Uses a specific silane compound (a-1) in consideration of the polarity and reactivity with the polyfunctional (meth) acrylate (d), and in the presence of colloidal silica, the silane compound (a-1)
Is obtained by surface modification by hydrolysis and polycondensation.

The curable composition of the present invention uses the silica-based polycondensate (a) to uniformly form fine silica particles in the polyfunctional (meth) acrylate (d) having extremely high hydrophobicity without agglomeration. The composition is excellent in fluidity and transparency.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail.

The component (a) used in the present invention is obtained by converting the (meth) acryloyloxysilane compound (a-1) represented by the general formula (I) into the presence of colloidal silica having an average particle diameter of 1 to 100 nm. It is a silica-based condensation polymer obtained by hydrolysis and condensation polymerization. In this specification, “(meth) acryloyl” indicates “acryloyl and / or methacryloyl”.

In the silica-based polycondensate (a) obtained by such hydrolysis and polycondensation, a hydrolyzate of a silane compound is mainly retained on part or all of the surface of colloidal silica as spherical fine particles. This is a condensed polymer having a configuration in which the surface properties of colloidal silica are modified to be hydrophobic. This surface modification can be easily performed by causing hydrolysis and condensation polymerization of a specific silane compound in the presence of colloidal silica.

The colloidal silica used for obtaining the component (a) mainly has an average particle diameter of 1 to 100 nm.
Can be used in a state where the silica fine particles are dispersed in a colloidal state in a dispersion medium. The term “colloidal” as used herein means a state in which silica fine particles are uniformly and stably dispersed in a liquid (dispersion medium).

The dispersion medium is not particularly limited.
Alcohols such as isopropyl alcohol, cellosolves, dimethylacetamide, xylene, water and the like can be used. Particularly, alcohols, cellosolves, and water are preferable.

The general formula (I) used for obtaining the component (a)
(Meth) acryloyloxysilane compound (a-1) represented by the formula: Methyldimethoxysilane and the like are preferred. Among them, γ-methacryloyloxypropylmethyldimethoxysilane is particularly preferred.

The amount of the silane compound (a-1) used to obtain the component (a) is not particularly limited, and may be appropriately determined as desired. The amount of colloidal silica added is preferably 1 to 100 parts by weight, more preferably 5 to 50 parts by weight, based on 100 parts by weight of the solid content (silica content). As described above, when the addition amount of the silane compound (a-1) is appropriately increased, the dispersibility becomes good, and when the addition amount is appropriately reduced, the physical properties are hardly inhibited. That is, by setting the content within the above preferable range, a curable composition having both excellent dispersibility and physical properties can be obtained.

In the production method of the present invention, when producing the silica-based condensation polymer (a), the hydrolysis and the condensation polymerization reaction are carried out at a reaction temperature of 45 to 100 ° C. and a reaction time of 3 to 24 hours. Particularly, the reaction temperature is 60 to 100 ° C., and the reaction time is 3 to 10
It is preferable to carry out under the condition of time. Further, these reactions are preferably performed under stirring. If the polycondensation reaction is carried out at a low temperature for a short time outside of this range, the hydrolysis and the polycondensation reaction become insufficient, and even when the silane compound (a-1) is used, the silica surface is sufficiently treated with the silane compound. Tend not to be. For this reason, the reaction system tends to cause aggregation, decrease transparency, and increase the viscosity to form a gel.

An inorganic acid or an organic acid can be used as a catalyst for performing a hydrolysis or condensation reaction for obtaining the silica-based condensation polymer (a). As the inorganic acid, for example, hydrochloric acid, hydrofluoric acid, hydrohalic acid such as hydrobromic acid, sulfuric acid,
Phosphoric acid and the like. Examples of the organic acid include formic acid, acetic acid, oxalic acid, acrylic acid, methacrylic acid and the like. Among them, it is particularly preferable to use an aqueous solution of hydrochloric acid of 0.01N or more.

A solvent can be used in the hydrolysis-condensation reaction system in order to moderate the reaction and make the reaction uniform. As the solvent, those having good compatibility with the reactant silane compound, water and the catalyst are preferable. Specific examples include water,
Examples thereof include alcohols such as isopropyl alcohol, ketones such as acetone, and ethers such as dioxane.
Further, the above-mentioned colloidal silica dispersion medium may be used as it is, or may be newly added in a necessary amount. The amount of the solvent used is not particularly limited as long as the reactants can be uniformly dissolved. To keep the concentrations of the reactants from becoming too dilute,
That is, it may be appropriately adjusted so that the reaction rate does not significantly decrease.

The silica-based condensation polymer (a) described above is
By uniformly dispersing the poly (meth) acrylate (d) containing the di (meth) acrylate (b) and the di (meth) acrylate (c), a curable composition can be obtained.

The di (meth) acrylate (b) is a highly hydrophobic di (meth) acrylate represented by the general formula (II). It is derived, for example, from bisphenol A. The hydrophobicity of the component (b) depends on the number of ethyleneoxy groups (m, n) in the general formula (II), and in terms of higher hydrophobicity, m and n in the general formula (IV) Preferably, each is independently 1 or 2. Also, R
It is also preferred that ⁴ is a methyl group. In particular, component (b)
Is more preferably 2,2′-bis (4-methacryloyloxyethoxyphenylpropane).

The di (meth) acrylate (c) is at least one selected from the group consisting of alkanediol di (meth) acrylate and polyethylene glycol di (meth) acrylate. Among them, triethylene glycol dimethacrylate is preferred.

The polyfunctional (meth) acrylate (d) used in the present invention is the above-mentioned di (meth) acrylate (b) 1
0 to 50 parts by weight, and 0 to 50 parts by weight of di (meth) acrylate (c) [provided that the total of the components (b) and (c) is 100 parts by weight]. The polyfunctional (meth) acrylate (d) may further contain a polyfunctional (meth) acrylate other than the components (b) and (c) as long as the polarity is not significantly increased, depending on the purpose of use and the like. . Examples of the polyfunctional (meth) acrylate other than the components (b) and (c) include a urethane-based polyfunctional (meth) acrylate. The content of the polyfunctional (meth) acrylate other than the components (b) and (c) is preferably 40% by weight or less in the component (d).

The curable composition of the present invention may contain a polyfunctional (meth) compound as long as the crosslink density is not significantly reduced.
In addition to acrylate (d), monofunctional (meth) such as methyl methacrylate, benzyl methacrylate, 2-hydroxyethyl methacrylate, and n-butyl methacrylate
Acrylates may be mixed and used.

In the present invention, the ratio of the amount of the polyfunctional (meth) acrylate (d) to the amount of the silica-based condensed polymer (a) is not particularly limited, and is appropriately determined according to the purpose of use. I just need. From the viewpoint that the dispersion effect of the silica-based condensation polymer (a) is exhibited and the viscosity of the curable composition does not become extremely high, the total of the silica-based condensation polymer (a) and the polyfunctional (meth) acrylate (d) It is preferable that the component (a) is 5 to 70 parts by weight based on 100 parts by weight.

The polymerization initiator (e) used in the present invention may be arbitrarily selected according to the use of the curable composition, a polymerization method suitable for the purpose, and the like. In the case of thermal polymerization, various peroxides,
The azo compound can be used for bulk polymerization and suspension polymerization. In particular, in the case of suspension polymerization, transparent polymer beads in which colloidal silica is uniformly dispersed can be obtained. In the case of photopolymerization using visible light or ultraviolet light, benzophenones, benzoin alkyl ethers, anthraquinones, thioxanthones, acylphosphine oxides, α-diketones and the like can be used. In the case of photopolymerization, a reducing agent such as a tertiary amine may be used in combination. Further, an oxidizing agent such as a peroxide and a reducing agent such as an amine may be separately compounded and mixed at the time of use to perform redox polymerization. The amount of the polymerization initiator (e) used is based on 100 parts by weight of the polyfunctional (meth) acrylate (d).
0.01 to 10 parts by weight is preferred.

The curable composition of the present invention comprises the above-mentioned components (a) to (e) as main components.
Depending on the purpose, etc., inorganic fillers such as silica powder, quartz powder, and glass beads having an average particle diameter of more than 100 nm; polymethyl methacrylate, polyethyl methacrylate, and (meth) acrylate structure as main repeating units A filler such as a (meth) acrylate-based polymer such as a copolymer may be blended. The compounding amount of these fillers is 100 total of the silica-based condensation polymer (a), the polyfunctional (meth) acrylate (d) and the polymerization initiator (e).
It is preferably from 10 to 900 parts by weight based on parts by weight.

The curable composition of the present invention may further contain, if necessary, pigments such as titanium oxide and iron oxide, ethanol,
Solvents such as ethyl acetate, polymerization inhibitors such as hydroquinone and phenols, rubbers, oxidation stabilizers, and ultraviolet absorbers can also be added.

Further, the curable composition of the present invention is excellent in dispersibility, fluidity and transparency, so that it is very useful for various uses such as optical materials, paint materials and dental materials.

[0035]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following description, “parts” means “parts by weight” unless otherwise specified.

<Example 1> (Preparation of Colloidal Silica Dispersion) Isopropyl alcohol-dispersed colloidal silica [silica content 30% by weight,
Average particle size 10-20 nm, trade name: Snowtex I
PA-ST; manufactured by Nissan Chemical Co., Ltd.] 100 parts of γ-methacryloyloxypropylmethyldimethoxysilane
And 3 parts of a 0.01 N hydrochloric acid aqueous solution, and the mixture was stirred at 70 ° C. for 7 hours.

Thereafter, 110 parts of 2,2'-bis (4-methacryloxyethoxyphenyl) propane was added, and all volatile components were distilled off under reduced pressure to obtain a colloidal silica dispersion. This colloidal silica dispersion had uniform dispersion of colloidal silica in the form of primary particles in the system, and had excellent transparency and fluidity.

(Preparation of curable composition) To 10 parts of this colloidal silica dispersion, 0.03 part of camphorquinone as a photopolymerization initiator and 0.2 part of ethyl p-dimethylaminobenzoate as a reducing agent were added and dissolved. To obtain a curable composition.

(Formation of Cured Product) The curable composition was filled in a stainless steel mold (inner diameter 10 mm, thickness 1 mm) having a cover glass with a thickness of 0.1 mm on the lower surface, and the same cover glass was placed on the upper surface. And then irradiated with light from both sides using a visible light irradiator (trade name: GC Light; manufactured by GC Corporation) for 60 seconds to obtain a cured product.

The cured product was measured for total light transmittance (%) in accordance with JIS K6714. Table 1 shows the results.

Example 2 Instead of the polyfunctional (meth) acrylate in Example 1, a mixture of 88 parts of 2,2'-bis (4-methacryloyloxyethoxyphenyl) propane and 22 parts of triethylene glycol dimethacrylate was used. A curable composition was prepared and a cured product was formed in the same manner as in Example 1 except that the composition was used. Table 1 shows the results.

Comparative Examples 1 and 2 Curable compositions were prepared in the same manner as in Examples 1 and 2, except that the reaction time was changed to 1 hour among the reaction conditions in Examples 1 and 2.
A cured product was formed. Table 1 shows the results.

Comparative Example 3 A colloidal silica dispersion was prepared in the same manner as in Example 1, except that 12 parts of γ-methacryloyloxypropyltrimethoxysilane were used instead of the silane compound in Example 1. It became a transparent gel substance and did not show fluidity.

<Comparative Example 4> A curable composition was prepared in the same manner as in Comparative Example 3 except that the reaction time was changed to 1 hour among the reaction conditions in Comparative Example 3. It became a substance and did not show fluidity.

[0045]

[Table 1] As is clear from the results shown in Table 1, in Examples 1 and 2 in which the specific silane compound specified in the present invention and the reaction temperature and reaction time in the specific range were adopted, the surface-modified colloidal silica was composed of primary particles. The colloidal silica dispersion liquid has a high transparency and a suitable fluidity as compared with Comparative Examples 1 to 4, which are uniformly dispersed in a polyfunctional (meth) acrylate in the state described above and employ other conditions and the like. Was.

[0046]

As described above in detail, the curable composition of the present invention is obtained by uniformly dispersing nm-order silica particles in a highly hydrophobic polyfunctional (meth) acrylate by using a specific reaction component. It is a composition that gives a cured product having excellent fluidity and excellent transparency, hardness and abrasion resistance.

Further, the method for producing the curable composition of the present invention realizes sufficient hydrolysis, polycondensation reaction, and sufficient treatment under specific reaction conditions, and can easily and satisfactorily improve the curable composition of the present invention. Can be manufactured.

The curable composition of the present invention has dispersibility, fluidity,
Since it has excellent transparency, it is very useful for various uses such as optical materials, paint materials, and dental materials.

Claims (7)

[Claims] 1. In the presence of colloidal silica having an average particle diameter of 1 to 100 nm, the following general formula (I): (Wherein, R ¹ is a hydrogen atom or a methyl group, R ² is an alkyl group or a phenyl group having 1 to ³ carbon atoms, R ³ is a hydrogen atom or a hydrocarbon residue having 1 to 10 carbon atoms, q is 1 to 6 And a silica-based condensation polymer (a) obtained by hydrolyzing and condensation-polymerizing a (meth) acryloyloxysilane compound (a-1) represented by the following general formula (II): Formula 2 (Wherein, R ⁴ is a hydrogen atom or a methyl group, m and n each independently represent an integer of 1 to 5) di (meth) acrylate (b) 100 to 50 parts by weight, and
0 to 50 parts by weight of at least one di (meth) acrylate (c) selected from the group consisting of alkanediol di (meth) acrylate and polyethylene glycol di (meth) acrylate [provided that component (b) and component (c) Curable composition comprising: a polyfunctional (meth) acrylate (d) containing a polymerization initiator (e) and a polymerization initiator (e). 2. The curable composition according to claim 1, wherein the component (a-1) is γ-methacryloyloxypropylmethyldimethoxysilane. 3. The curable composition according to claim 1, wherein R ⁴ in the general formula (II) is a methyl group, and m and n are each independently 1 or 2. 4. The method according to claim 1, wherein the di (meth) acrylate (c) is triethylene glycol dimethacrylate.
4. The curable composition according to any one of 3. 5. A method for producing the curable composition according to claim 1, wherein the hydrolysis and the condensation polymerization for obtaining the silica-based condensation polymer (a) are carried out at a reaction temperature of 45 to 100 ° C. A method for producing a curable composition, which is performed for a reaction time of 3 to 24 hours. 6. The method for producing a curable composition according to claim 5, wherein an aqueous solution of hydrochloric acid of 0.01 N or more is used as a catalyst for hydrolysis and condensation polymerization to obtain the silica-based condensation polymer (a). 7. The production of a curable composition according to claim 5, further comprising a step of distilling off volatile components of a mixture obtained by adding a polyfunctional (meth) acrylate (d) to the silica-based condensation polymer (a). Method.