WO2012105297A1 - Process for producing functional colloidal silica solution, ultraviolet-curable resin composition for hard coats using same, and cured product thereof - Google Patents

Abstract

The present invention provides a process for producing a functional colloidal silica capable of yielding a ultraviolet-curable hard coat material which combines hardness and low cure shrinkage and which ensures excellent scratch resistance, tight adhesion and economical efficiency. A process for producing a functional colloidal silica solution which is obtained by subjecting (A) 100 parts by weight (in terms of silica) of a water-dispersible colloidal silica that has a mean particle diameter of 1 to 30nm and a hydrogen ion concentration (pH) of 6 or less, (B) 20 to 30 parts by weight of a methacryloxy-containing alkoxysilane and (C) 50 to 500 parts by weight of a polar solvent having a dielectric constant of 10 or more to hydrolysis in the presence of (D) 0.001 to 1 part by weight of (D) a radical polymerization inhibitor, and then subjecting the resulting system to azeotropic dehydration/ solvent displacement using (E) 1-methoxy-2-propanol and which exhibits a mean particle diameter of 1 to 30nm and an at most 1.5-fold difference in the mean particle diameter of the silica between before and after the hydrolysis.

Description

Method for producing functional colloidal silica solution, resin composition for ultraviolet curable hard coat using the same, and cured product thereof

The present invention relates to a functional colloidal silica solution used for forming a protective film excellent in pencil hardness, abrasion resistance, low curling property, adhesion and economy on the surface of optical films such as polycarbonate and plastic parts. The present invention relates to a production method, an ultraviolet curable hard coat resin composition, and a cured product thereof.
Background art

Optical film and plastic parts such as polycarbonate, polymethylmethacrylate, polystyrene, polyester, triacetylcellulose, etc. are used to prevent the surface from being scratched by handling during production and to prevent scratches caused by user use. A protective hard coat layer is provided on one side or both sides.

This hard coat layer generally has a film thickness of 1 to 20 μm, and various active energy ray curable resins and thermosetting resins are used. However, when a hard coat layer is provided, there are insufficient pencil hardness, poor adhesion, and film curling, and improvements have been desired.

In JP-A-57-13214 (Patent Document 1) and JP-A-2009-102503 (Patent Document 2), a composition of particles and an acrylate obtained by treating the surface of water-dispersible colloidal silica with methacryloxysilane is disclosed. And use as a photo-curing coating agent. This coating agent is characterized in that the performance of the coating agent is improved by treating the surface of the silica particles with a specific organosilane and a specific condition.
However, such a coating agent is not always satisfactory. In other words, in order to improve the hardness of the protective film, it is necessary to increase the crosslink density of the film after curing. However, if the hardness of the film is increased, warpage and curl due to curing shrinkage increase, and the hardness and low curling property are increased. There was a problem that it was difficult to balance.

In JP 2009-91448 A (Patent Document 3), the surface of a water-dispersible colloidal silica is treated with methacryloxysilane and the main component is silica and pentaerythritol triacrylate, so that the hardness and low curling property of the film are reduced. Although some improvement was seen, further improvement was desired.

On the other hand, in Japanese Patent Application Laid-Open No. 7-109355 (Patent Document 4), the hardness of the film is improved by using as a main component silica and an acrylate monomer whose surface is treated with methacryloxysilane on the surface of solvent-dispersible colloidal silica. However, since the expensive solvent-dispersible colloidal silica is used as a starting material, the final product obtained is also expensive, which is disadvantageous in terms of economy.

JP 57-13214 A JP 2009-102503 A JP 2009-91448 A JP 7-109355 A

In the prior art, the surface hardness was increased by using many polyfunctional acrylate monomers or adding colloidal silica whose surface was treated with a specific organosilane, but when using many polyfunctional acrylate monomers. In particular, problems often occur in curing shrinkage.
In order to solve such a shrinkage problem, it is conceivable to reduce the shrinkage by replacing the acrylic monomer resin skeleton itself with a soft component. There was a problem that the hard coating agent for surface protection was not suitable.

Further, even when the amount of the surface-treated colloidal silica was increased, the surface hardness was not sufficiently improved, and the brittleness of the film and the decrease in adhesion were sometimes observed.

Therefore, it is basically difficult to reduce the curing shrinkage while maintaining the hardness, and there has been a demand for a hard coat agent that achieves both hardness and low curing shrinkage and is excellent in adhesion.

The present invention has been made in view of the above problems, and its purpose is to form a pencil hardness, scratch resistance, film curling, adhesion, economy when a hard coat layer is formed on the surface of an optical film or plastic part. The present invention provides a method for producing a functional colloidal silica solution used in a hard coat resin composition with improved properties, and a hard coat resin composition using the functional colloidal silica solution obtained by the method. .

The present inventor has solved the above-mentioned problems of the prior art and provides a functional colloidal silica to provide an ultraviolet curable hard coat agent which has both hardness and low curing shrinkage and is excellent in scratch resistance, adhesion and economy. As a result of intensive studies, the inventors found that an ultraviolet curable hard coating agent using a functional colloidal silica solution having a particle size in a certain range synthesized by the following composition and process is extremely effective and completes the present invention. It came to.

That is, the present invention
(A) Water-dispersible colloidal silica having an average particle diameter of 1 to 30 nm and a hydrogen ion concentration (pH) of 6 or less; 100 parts by weight as silica content
(B) Methacrylic group-containing alkoxysilane; 20 to 30 parts by weight
(C) a polar solvent having a dielectric constant of 10 or more; 50 to 500 parts by weight
(D) radical polymerization inhibitor; after the hydrolysis reaction in the presence of 0.001 to 1 part by weight,
(E) Obtained by azeotropic dehydration using 1-methoxy-2-propanol and solvent substitution, the average particle size is 1 to 30 nm, and the difference in the average particle size of silica before and after the hydrolysis reaction is 1 A method for producing a functional colloidal silica solution within 5 times,
And the functional colloidal silica solution, an acrylate resin and / or a urethane acrylate resin, and a photopolymerization initiator, an ultraviolet curable hard coat resin composition, wherein the solid content based on the functional colloidal silica solution UV-curable hard coat resin composition having a solid content of 50% or more,
And an optical film or a plastic part having a hard coat layer having a thickness of 1 to 20 μm, which is formed by applying the ultraviolet curable hard coat resin composition and then curing by ultraviolet irradiation.

According to the present invention, when a hard coat layer is formed on an optical film and a plastic part, it is possible to provide a hard coat resin composition with improved pencil hardness, scratch resistance, adhesion, and film curling at a relatively low cost. it can.
Detailed Description of the Invention

Hereinafter, the present invention will be described in detail.

The component (A) used in the present invention is water-dispersible colloidal silica having an average particle size of 1 to 30 nm and a hydrogen ion concentration (pH) of 6 or less.
Generally, colloidal silica fine particles are obtained by dispersing ultrafine particles of silicic anhydride having an average particle size of 1 to 200 μm in water or an organic solvent.
Dispersion media used for colloidal silica include alcohol solvents such as water, methanol, ethanol, isopropanol, n-propanol, isobutanol and n-butanol, polyhydric alcohol solvents such as ethylene glycol, ethyl cellosolve, butyl cellosolve, etc. Polyhydric alcohol derivatives, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and diacetone alcohol, and monomers such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate and tetrahydrofurfuryl acrylate. From the viewpoint of the hydrolysis reaction step, water-dispersible colloidal silica having a hydrogen ion concentration (pH) of 6 or less is particularly preferable.
These colloidal silicas are produced by a known method, and those having a concentration of about 5 to 40% mainly as a silica content are preferable.
The average particle size is 1 to 30 nm, preferably 10 to 30 nm, more preferably 15 to 30 nm, and still more preferably 18 to 25 nm. Those having a particle diameter of less than 1 nm are expensive, and gelation tends to occur in the reaction process. Moreover, the thing with a particle diameter exceeding 30 nm reduces the transparency of a cured film. Colloidal silica can remarkably improve the scratch resistance of the cured film and is effective in imparting anti-curl properties.
In the present invention, since the water in the colloidal silica is finally azeotropically dehydrated and solvent-substituted, it is preferable that the silica concentration in the colloidal silica is high from the economical aspect, and the concentration can be increased. An average particle size of about 18 to 25 nm is optimal.
In the present invention, those having an average particle diameter in the range of 18 to 25 nm and silica in the range of 30 to 40% are preferable.

By blending a certain amount of the component (B) with respect to the effective amount of the colloidal silica, it can be chemically bonded to the colloidal silica by hydrolysis under an acidic aqueous solution, and the scratch resistance of the cured film can be remarkably improved. .
As such silanes, 3-methacryloxypropyltrimethoxysilane, 2-methacryloxyethyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 2-methacryloxyethyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane However, 3-methacryloxypropyltrimethoxysilane is preferred because of its availability.
The blending amount must be 20 to 30 parts by weight with respect to 100 parts by weight of the effective component (silica content) of component (A).
If the amount is less than 20 parts by weight, the surface treatment of the colloidal silica is not sufficiently performed, and as a result, sufficient wear resistance cannot be obtained. Further, the colloidal silica particles may aggregate in the dehydration step after hydrolysis. When the amount is more than 30 parts by weight, the change in the particle size of the functional colloidal silica solution obtained becomes large, and sufficient hardness and scratch resistance are not exhibited when the ultraviolet curable hard coat composition is prepared. In addition, an excessive component (B) forms an oligomer during hydrolysis, which affects pencil hardness and wear resistance. Furthermore, the curl becomes large when applied to a film substrate.

Component (C) is blended in order to improve compatibility when the components (A) and (B) are hydrolyzed.
Examples of polar solvents having a dielectric constant of 10 or more include 1-butanol, 2-butanol, methanol, ethanol, cellosolve, etc., but compatibility between components (A) and (B) before and after the hydrolysis reaction, colloidal silica Isopropyl alcohol and / or 1-methoxy-2-propanol are preferred from the standpoints of influence on particle size and efficiency of azeotropic dehydration. The amount is preferably 50 to 500 parts by weight, particularly preferably 70 to 150 parts by weight from the viewpoints of compatibility and the solvent distillation efficiency after the hydrolysis reaction.

The (D) component can suppress the polymerization of methacrylic groups and improve the yield by allowing it to coexist during the hydrolysis reaction of the (A) component and the (B) component.

The radical polymerization inhibitor is not particularly limited, and any radical polymerization inhibitor can be used as long as it is generally used as a radical polymerization inhibitor.
Specifically, quinone polymerization inhibitors such as hydroquinone, methoxyhydroquinone, benzoquinone and p-tert-butylcatechol; 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2-tert- Alkylphenol polymerization inhibitors such as butyl-4,6-dimethylphenol, 2,6-di-tert-butyl-4-methylphenol, 2,4,6-tri-tert-butylphenol; alkylated diphenylamine, N, N '-Diphenyl-p-phenylenediamine, phenothiazine, 4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 1,4-dihydroxy- 2,2,6,6-tetramethylpiperidine, 1-hydroxy-4- Amine polymerization inhibitors such as benzoyloxy-2,2,6,6-tetramethylpiperidine; copper dithiocarbamate polymerization inhibitors such as copper dimethyldithiocarbamate, copper diethyldithiocarbamate, copper dibutyldithiocarbamate; 2,2, 6,6-tetramethylpiperidine-1-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-1 1-oxyl polymerization inhibitors such as -oxyl, esters of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl; and the like.

Among these, preferable radical polymerization inhibitors include quinone polymerization inhibitors, amine polymerization inhibitors, copper dithiocarbamate polymerization inhibitors, and 1-oxyl polymerization inhibitors.
Particularly preferred radical polymerization inhibitors include hydroquinone, methoxyhydroquinone, benzoquinone, p-tert-butylcatechol, phenothiazine, alkylated diphenylamine, copper dibutyldithiocarbamate, 2,2,6,6-tetramethylpiperidine-1-oxyl, 4 Examples include -hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, esters of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, and the like. The blending amount is preferably 0.001 to 1 part by weight from the viewpoint of the effect of suppressing the radical polymerization reaction during the hydrolysis reaction and the reactivity of the hard coat composition with respect to ultraviolet rays when prepared into a hard coat composition. 01 to 0.1 parts by weight are preferred.

The component (E) is used when water or by-products are distilled off from the system after the hydrolysis reaction.
Conventionally, acrylates with low viscosity such as 1,6-hexanediol diacrylate and tripropylene glycol diacrylate are blended to remove water and by-products by distillation, isobutanol, toluene, IPA (isopropanol) Dehydration or azeotropic dehydration was performed using a solvent such as DMF (dimethylformamide). When dehydration is performed using these materials, the silica particle diameter in the finally obtained functional colloidal silica solution becomes large, and as a result, when prepared into a resin composition for hard coat, pencil hardness, There was an effect on wear and low curl properties.
In addition, when an acrylate having a low viscosity is blended, the obtained functional colloidal silica already contains a specific acrylate, so the properties of the hard coat composition to be finally prepared are limited. Therefore, since it cannot be treated as a versatile masterbatch-like functional colloidal silica, its value is limited.
In addition, any acrylate having such a low viscosity is bifunctional, and a composition containing this acrylate is not suitable for the present invention aiming at high hardness and scratch resistance.
On the other hand, when 1-methoxy-2-propanol is used, there is almost no change in the silica particle diameter in the functional colloidal silica solution before and after hydrolysis. Further, since the azeotropic ratio during dehydration is high, the dehydration efficiency is high and the productivity is excellent.
Moreover, since it is excellent in compatibility with functional colloidal silica, it can be concentrated to a high concentration without an increase in viscosity and thixotropy. Moreover, since it does not contain acrylate or the like, it can be handled as a versatile master batch.
Furthermore, 1-methoxy-2-propanol is suitable for hard coat resin compositions for films and various plastics because it does not affect plastic substrates that are easily affected by organic solvents such as polycarbonate. . The blending amount is not particularly limited as long as it is necessary for azeotropic dehydration and there is an amount capable of stably dispersing the obtained functional colloidal silica.

To produce this functional colloidal silica solution, the components (A) to (C) are hydrolyzed in the presence of the component (D) in the first step. The conditions at this time are not particularly limited, but generally 70 to 120 ° C., more preferably 2 hours or more at the reflux temperature is appropriate.

Next, in the second step, azeotropic dehydration is performed using the component (E) to obtain a functional colloidal silica solution. The conditions for azeotropic dehydration are not particularly limited, but azeotropic dehydration is preferably performed under reduced pressure so that the solution temperature does not become 50 ° C. or higher.

It should be noted that additives such as a silane coupling agent, a leveling agent, an acrylate, a urethane acrylate, and a diluting solvent can be blended within a range not impairing the characteristics of the present invention.

In the present invention, as described above, the average amount of silica particles before and after the hydrolysis reaction is controlled by controlling the blending amount of the methacryl group-containing alkoxysilane and selectively using 1-methoxy-2-propanol for azeotropic dehydration. A functional colloidal silica solution having a diameter difference of 1.5 times or less can be produced.

In order to prepare a resin composition for an ultraviolet curable hard coat using this functional colloidal silica solution, an acrylate resin or a urethane acrylate resin is blended as a binder component, a photopolymerization initiator, a diluting solvent if necessary, and leveling. It can be obtained by blending agents, but in order to obtain a UV-hardening hard coat resin composition with essentially high hardness, a trifunctional or higher polyfunctional type acrylate or urethane acrylate is mainly used as a binder component. It is preferable to do.

In addition, from the viewpoints of hardness, scratch resistance, and low curl properties, the UV curable type is such that the solid content (active ingredient) based on the functional colloidal silica solution is 50% or more of the total solid content (active ingredient). It is necessary to prepare a resin composition for hard coat, and it is particularly preferably 60% or more.

If the composition satisfies the above conditions, the effect of the present invention can be obtained. As a specific composition, a functional colloidal silica solution; an acrylate resin and / or urethane with respect to 100 parts by weight as a silica component A suitable amount is 40 to 100 parts by weight of an acrylate resin, 4 to 16 parts by weight of a photopolymerization initiator, and 200 to 1000 parts by weight as the total solvent content.

The acrylate resin, urethane acrylate resin, photopolymerization initiator, and diluting solvent used in the present invention are not particularly limited as long as they are conventionally used in ultraviolet curable hard coat resin compositions. Dipentaerythritol hexaacrylate, pentaerythritol pentaacrylate, dipentaerythritol pentaacrylate, pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate and the like.

Urethane acrylate resins include urethane acrylates “purple light UV-1700B”, “purple light UV-6300B”, “purple light UV-7640B” manufactured by JSR Corporation, Ebecryl® 1290 manufactured by Daicel-Cytec, and “UA-306H” manufactured by Kyoeisha Chemical. Or the like.

As the photopolymerization initiator, any known and generally available ones can be used, but those having a maximum wavelength peak of UV absorption of 400 nm or less are particularly desirable in order to ensure transparency in the visible region.
As such a polymerization initiator, acetophenone-based 1-hydroxy-cyclohexyl-phenyl ketone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-hydroxy-2-methyl-1-phenyl-propane -1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone -1-one, phosphine oxide 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, benzophenone and polymerization accelerators ethyl-4-dimethylaminobenzoate, 2-ethylhexyl-4-dimethylaminobenzoate Combinations such as these can also be used.

As the diluting solvent, known solvents such as alcohol solvents such as 1-methoxy-2-propanol, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, and ester solvents such as ethyl acetate and butyl acetate can be used. It can be used alone or in a mixed solvent system.

In addition, it is desirable that the resin composition for hard coat be filtered before use. The filter material is preferably PTFE, polypropylene, or the like that is not easily eroded by an acrylic compound, and the filter diameter during filtration is preferably about 0.2 to 10 microns because it is easily available. In particular, the filter diameter is divided into two stages, with the passage of 2 to 10 microns in the early stage and 0.2 to 1 micron in the latter stage, so that colloidal silica agglomerates, gels derived from acrylic resin, and dust mixed in from the air are more efficient. It can be removed well and the final appearance of the film can be kept good.

The UV curable hard coat composition described above is applied to the surface of an optical film or plastic part substrate by roll, wire bar, doctor blade, flow, spray, brushing, etc. It can be cured by irradiating with ultraviolet rays. As the ultraviolet light source, any light source that generates ultraviolet light can be used without limitation.
For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a fusion lamp, or the like can be used.
Irradiation conditions vary depending on each lamp, but in the case of a fusion lamp (H bulb), the amount of irradiation light is preferably about 50 to 1000 mJ / cm ^{2 in} the ultraviolet UV-B wavelength region. The ultraviolet curable hard coat composition is preferably irradiated with ultraviolet rays during or after coating and drying, and the irradiation time is preferably 0.5 seconds to 5 minutes. From the viewpoint of curing efficiency or work efficiency of the ultraviolet curable resin, 3 More preferred is seconds to 2 minutes.

In the present invention, the formation thickness of the ultraviolet curable hard coat agent is 1 to 20 μm, preferably 5 to 15 μm. When the film thickness decreases, the influence of polymerization inhibition by oxygen during photocuring increases, and a curing system under an inert gas such as nitrogen is required. Further, when the film thickness becomes extremely large, there is a problem that the deformation of the base material during curing shrinkage becomes large.
Example

Examples of the present invention will be described below, but the present invention is not limited to the following examples. Moreover, a part shows a weight part in an Example.

The evaluation method is as follows.
(Average particle size)
The measurement was performed with a submicron particle size distribution analyzer Coulter N4 Plus manufactured by Beckman Coulter.
(Pencil hardness)
The test was conducted on the film surface on which the cured film was formed according to the test method of JIS K 5600-5-4. However, after conditioning for 16 hours or more under the conditions of 23 ° C. and 50% RH, the load is 1 kg, the test is performed five times with a pencil of the same hardness scale, the type of indentation is visually examined, and the plasticity for each hardness scale Evaluation was performed by the number of times without deformation or cohesive failure / number of tests.
(Abrasion resistance)
Using the Taber abrasion test described in JIS K 7204 and JIS K 7105 using two wheels with a wear wheel CS10F and a load of 250 g on one wheel, and subtracting the haze (haze) at the time of 500 rotations from the initial haze, Abrasion was evaluated. The lower the value, the better the wear resistance.
(Curl property)
The sample was cut out with a size of 100 mm × 100 mm square, and conditioned for 16 hours or more under the conditions of 23 ° C. and 50% RH, and then the lifted distances at the four corners of the sample were measured to obtain an average value.
(Adhesion)
A lattice-shaped crosscut was prepared on the surface of the film on which the cured film was formed according to the test method of JIS K 5600-5-6, and a cellophane tape peeling test with a width of 25 mm was performed. The evaluation of adhesion was shown by the number of remaining eyes / total number of eyes.

Synthesis example 1
430 parts of isopropyl alcohol (IPA), Snowtex O-40 manufactured by Nissan Chemical Industries, Ltd. (water-dispersible colloidal silica; silica content 40%, pH of about 3, particle size 16.7 nm), 1340 parts, Momentive Performance Material A mixture of 140 parts TSL8370 (3-methacryloxypropyltrimethoxysilane) and 0.35 parts 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy free radical manufactured by The mixture was refluxed with stirring at about 82 ° C. for 3 hours.

After cooling, 500 parts of 1-methoxy-2-propanol (PGM) was added, and isopropyl alcohol and by-product methanol were distilled off under reduced pressure. Further, 850 parts of 1-methoxy-2-propanol was added in several portions, and water was distilled off under reduced pressure by azeotropic distillation so that the nonvolatile content was 60%. The nonvolatile content was measured under the condition of 150 ° C./30 minutes. Finally, a 1-methoxy-2-propanol solution (FCS-1) of functional colloidal silica having a nonvolatile content of 60% was prepared.

Synthesis example 2
430 parts of isopropyl alcohol used in Synthesis Example 1 were replaced with 830 parts of 1-methoxy-2-propanol, and the total amount of 1-methoxy-2-propanol used for distillation under reduced pressure was changed from 1350 parts to 620 parts (methanol). The ratio used for the vacuum distillation of the water and the like by azeotropic distillation is the same as in Synthesis Example 1. The same applies hereinafter. A 1-methoxy-2-propanol solution (FCS-2) of functional colloidal silica having a content of 60% was prepared.

Synthesis example 3
After cooling, 500 parts of 1-methoxy-2-propanol was added together with 275 parts of pentaerythritol triacrylate, and the total amount of 1-methoxy-2-propanol used for distillation under reduced pressure was increased from 1350 parts. Substituting 1530 parts, a 1-methoxy-2-propanol solution (FCS-3) of functional colloidal silica having a nonvolatile content of 60% was finally prepared in the same procedure as in Synthesis Example 1.

Synthesis example 4
430 parts of isopropyl alcohol, Snowtex O-40 manufactured by Nissan Chemical Industries, Ltd. (water-dispersible colloidal silica; silica content 40%, pH about 3, particle size 16.7 nm), 1340 parts, Momentive Performance Materials Japan A mixture of 140 parts TSL8370 (3-methacryloxypropyltrimethoxysilane) and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy free radical 0.35 parts manufactured by The mixture was stirred and refluxed at 82 ° C. for 3 hours.

After cooling, 357 parts of 1,6-hexanediol diacrylate (HDDA) was added, and isopropyl alcohol, by-produced methanol and water were distilled off under reduced pressure to adjust the nonvolatile content to 98% or more. Finally, a solution of functional colloidal silica having a nonvolatile content of 98% or more (FCS-4; internal functional silica content of about 60%) was prepared.

Synthesis example 5
430 parts of isopropyl alcohol, Snowtex O-40 manufactured by Nissan Chemical Industries, Ltd. (water-dispersible colloidal silica; silica content 40%, pH about 3, particle size 16.7 nm), 1340 parts, Momentive Performance Materials Japan A mixture of 140 parts TSL8370 (3-methacryloxypropyltrimethoxysilane) and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxy free radical 0.35 parts manufactured by The mixture was stirred and refluxed at 82 ° C. for 3 hours.

After cooling, 500 parts of isobutanol (IBA) was added, and isopropyl alcohol and by-product methanol were distilled off under reduced pressure. Further, 1720 parts of isobutanol was added in several portions, and finally an isobutanol solution (FCS-5) of functional colloidal silica having a nonvolatile content of 60% was prepared.

Synthesis Example 6
The amount of TSL8370 was increased from 140 parts to 240 parts, and finally a 1-methoxy-2-propanol solution (FCS-6) of functional colloidal silica having a nonvolatile content of 60% was synthesized by the same synthesis procedure as in Synthesis Example 1. ) Was produced.

Examples 1 to 4
The functional colloidal silica solutions obtained in Synthesis Examples 1 to 3, the pentaerythritol triacrylate (PETA), and the urethane acrylate (UA; manufactured by JSR Corporation) so that the ultraviolet curable hard coat composition described in Table 1 is obtained. UV-7640B), Irgacure 184 (photopolymerization initiator) manufactured by BASF Japan Ltd., 1-methoxy-2-propanol and the like were prepared, followed by pressure filtration to obtain a hard coat solution. The unit in the table is part by weight.

The hard coat solution thus obtained was applied to a 188 μ-thick easy-adhesive PET film (Lumilar U34 manufactured by Toray Industries Inc.) with a bar coater so as to have a coating thickness of 10 μm, and after curing at 90 ° C. for 1 minute. Using a F450T-10 manufactured by Fusion, an H bulb, a hard coat film was formed by irradiation four times under an ultraviolet irradiation condition of 200 mJ / cm ² (as UV-A). The evaluation results are shown in Table 1.

Comparative Examples 1 to 4
In the same manner as in Examples 1 to 4, the functional colloidal silica solution, pentaerythritol triacrylate obtained in Synthesis Examples 4 to 6 so as to be the ultraviolet curable hard coat composition described in Table 1, manufactured by JSR Corporation Urethane acrylate (purple UV-7640B), Irgacure 184 (photopolymerization initiator) manufactured by BASF Japan Ltd., 1-methoxy-2-propanol and the like were prepared. In Comparative Example 1, FCS-1 was added to prepare the composition shown in Table 1. A hard coat film was formed in the same manner as in Experimental Examples 1 to 4. The evaluation results are shown in Table 1.

As shown in Table 1, by controlling the blending amount of the methacrylic group-containing alkoxysilane as in Synthesis Examples 1 to 3, and by selectively using 1-methoxy-2-propanol for azeotropic dehydration, before and after the hydrolysis reaction A functional colloidal silica solution having a difference in average particle diameter of silica within 1.5 times can be produced. In contrast, in Synthesis Examples 4 and 5 using 1,6-hexanediol diacrylate (HDDA) or isobutanol (IBA) for azeotropic dehydration and in Synthesis Example 6 in which the amount of methacryl group-containing alkoxysilane is too large, Only a large average particle size was obtained.

In Examples 1 to 4 using the functional colloidal silica solution of the present invention, films excellent in pencil hardness, scratch resistance, curling property and adhesion were obtained.

Claims (4)

(A) Water-dispersible colloidal silica having an average particle diameter of 1 to 30 nm and a hydrogen ion concentration (pH) of 6 or less; 100 parts by weight as silica content
(B) Methacrylic group-containing alkoxysilane; 20 to 30 parts by weight
(C) Polar solvent having a dielectric constant of 10 or more; 50 to 500 parts by weight
(D) radical polymerization inhibitor; after the hydrolysis reaction in the presence of 0.001 to 1 part by weight,
(E) Obtained by azeotropic dehydration using 1-methoxy-2-propanol and solvent substitution, the average particle size is 1 to 30 nm, and the difference in the average particle size of silica before and after the hydrolysis reaction is 1 The manufacturing method of the functional colloidal silica solution which is less than 5 times. An ultraviolet curable hard coat resin composition comprising a functional colloidal silica solution obtained by the production method according to claim 1, an acrylate resin and / or a urethane acrylate resin, and a photopolymerization initiator, The resin composition for an ultraviolet curable hard coat whose solid content based on the functional colloidal silica solution is 50% or more based on the total solid content. The ultraviolet curable hard coat resin composition according to claim 2, wherein the acrylate resin and / or the urethane acrylate resin is trifunctional or higher. An optical film or plastic part having a hard coat layer having a thickness of 1 to 20 μm formed by applying the ultraviolet curable hard coat resin composition according to claim 2 or 3 and then curing by ultraviolet irradiation.