JPH05230246A - Molded object and production thereof - Google Patents

Abstract

PURPOSE:To improve surface hardness, adhesion, and durability by applying a silicon compound on a specific polymer surface having acid groups and converting the compound into a silica polymer through polycondensation to form a covering layer. CONSTITUTION:A composition containing at least 30wt.% polyfunctional monomer having two or more (meth)acryloyloxy groups per molecule is applied to the surface of a molding of an organic material and the monomer is polymerized to form a polymer layer having a thickness of 1mum or larger. The surface of the layer is irradiated with ultraviolet having a wavelength of 300nm or shorter and them immersed in a 0.1-50wt.% aqueous alkali solution at 0-100 deg.C for 0.01-100hr to generate acid groups in an amount of 0.02mumol/cm<2> or larger on the surface. The acid groups are covered with a silicon compound represented by the formula XaSi(OY)4-a (wherein X is an organic functional group containing an epoxy group, Y is a hydrocarbon group, and a is 1-3). The compound is subjected to hydrolysis and polycondensation in the presence of a perchloric acid compound, water, and an organic solvent to form a covering layer of a silica polymer.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a molded article having excellent surface hardness and a method for producing the same. The molded product obtained from the present invention can be used in various fields such as the field of construction, the field of automobiles, and the field of optics.

[0002]

2. Description of the Related Art Synthetic resin moldings such as polymethylmethacrylate resin, polycarbonate resin, and diethylene glycol bisallyl carbonate resin have the advantages of being lighter and cheaper than glass products, and taking advantage of these advantages. It is used in various fields. However, since the surface hardness of these synthetic resin molded products is insufficient, the surface is damaged by the action of contact with other objects, impact, scratching, etc. during transportation of the molded product, attachment of parts or use. Product yield is reduced and aesthetics are impaired. Especially when the molded product is used for optical lenses, fashion glasses, sunglasses, spectacle lenses such as corrective lenses, windows, etc., damages that occur on the surface will significantly reduce the commercial value or render it unusable in a short period of time. Therefore, it is strongly required to improve the surface hardness of the surface of these synthetic resin molded products.

Various attempts have hitherto been made in order to satisfy such requirements. JP-A-51-2736, JP-A-54-87736, JP-A-55-94
Abrasion resistance is improved by a coating composition containing a mixture of colloidal silica and a hydrolyzable silicon compound in a hydrolyzing medium such as alcohol or water as described in 971. In addition, I.KAETSU et al. Report (Journal of Applied Polymer Science vol.22 487-
496 (1978)), a coating composition using a hydrolyzable silicon compound containing an epoxy group and a (meth) acrylate compound containing an epoxy group is effective for improving the wear resistance of diethylene glycol bisallyl carbonate resin. It is said that.

[0004]

However, a film formed by the coating composition disclosed in JP-A-51-2736 and JP-A-54-87736 has a drawback that it is poor in resistance to moisture and humidity. Kaisho 55-94971
The coating film of the coating composition of Japanese Patent Laid-Open Publication has insufficient heat resistance and has a problem in durability such that cracks tend to occur in the coating film.
In addition, I.KAETSU's report (Journal of Applied Polymer S
cience vol.22 487-496 (1978)), it is said that a film obtained by polycondensation of a hydrolyzable silicon compound containing an epoxy group is difficult to obtain sufficient adhesion to polymethylmethacrylate resin and polycarbonate resin. ing. This is considered to cause poor adhesion because the surfaces of the polymethylmethacrylate resin and the polycarbonate resin do not have enough functional groups that chemically react with the epoxy groups.

A drawback of the coating composition in which the above-mentioned colloidal silica and hydrolyzable silicon compound are mixed is that the substrate is not subjected to an appropriate surface treatment and the functional groups on the substrate are insufficient, so that the colloid is not present. It is considered that the OH group on the surface of the crystalline silica and the OH group of the hydrolyzable silicon compound molecule are not chemically bonded to the base material.

[0006]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that a specific monomer,
As a result of employing ultraviolet irradiation and alkali treatment, a specific large amount of acidic groups can be generated on the surface of the molded product, and it was found that treating this portion with a silicon compound is very effective, and the present invention was completed.

That is, the molded article of the present invention has 2 in 1 molecule.
A polymer having a structural unit derived from a polyfunctional monomer having at least one (meth) acryloyloxy group as a main constituent unit at least in its surface layer portion, and 0.02 μmol / cm ² or more on the surface of this surface layer portion And a silica polymer obtained by polycondensing a silicon compound represented by the general formula (A) is laminated on the acidic group. is there. X _a Si (OY) _4-a (A) (In the formula, X is an organic functional group Y containing an epoxy group,
The hydrocarbon group a represents an integer of 1 to 3. )

Further, the method for producing a molded article according to the present invention comprises at least a polymer having as a main constituent unit a structural unit derived from a polyfunctional monomer having two or more (meth) acryloyloxy groups in one molecule. The molded product in the surface layer part is irradiated with ultraviolet rays having a wavelength of 300 nm or less and alkali-treated to generate 0.02 μmol / cm ² or more acidic groups in the surface layer part of the molded product, and then the above description Is treated with a silicon compound represented by the general formula (A).

[0009]

The molded article of the present invention and the method for producing the same will be described in detail below. In the present invention, first, at least the surface layer portion of the molded article is formed by polymerizing a composition containing a polyfunctional monomer having two or more (meth) acryloyloxy groups in one molecule. Examples of the polyfunctional monomer include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol (meth) acrylate, ethylene glycol di (meth) acrylate, Triethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate,
3-methylpentanediol di (meth) acrylate,
Diethylene glycol bis β- (meth) acryloyloxypropionate, trimethylolethanedi (meth)
Acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tri (2-hydroxyethyl) isocyanate di (meth) acrylate, pentaerythritol tetra (meth) acrylate, 2,3-bis (meth) acryloyloxyethyloxymethyl [2.2.1] heptane, poly 1,2-butadiene di (meth) acrylate,
1,2-bis (meth) acryloyloxymethylhexane, nonaethylene glycol di (meth) acrylate,
Tetradecane ethylene glycol di (meth) acrylate, 10-decanediol (meth) acrylate, 3,
8-bis (meth) acryloyloxymethyltricyclo [5.2.10] decane, hydrogenated bisphenol A di (meth) acrylate, 2,2-bis (4- (meth) acryloyloxydiethoxyphenyl) propane, 1 ，
4-bis ((meth) acryloyloxymethyl) cyclohexane, hydroxypivalic acid ester neopentyl glycol (meth) acrylate, bisphenol A diglycidyl ether di (meth) acrylate, epoxy modified bisphenol A di (meth) acrylate and the like can be mentioned. it can. As the polyfunctional monomer, only one kind may be used, or two or more kinds may be used in combination. If necessary, they can be used in combination with a monofunctional monomer for copolymerization. The polyfunctional monomer is 30% by weight in the composition.
The above is desirable. When the surface layer portion is formed using only a monofunctional monomer, a small amount of acidic groups can be obtained even after the subsequent irradiation of ultraviolet rays and alkali treatment, and the molded article intended by the present invention cannot be obtained. That is, in the present invention, a polyfunctional monomer (a polyfunctional monomer having two or more (meth) acryloyloxy groups in one molecule)
Using is one of the important components.

Further, in the present invention, a cured film may be formed by coating and supplying the above-mentioned polyfunctional monomer on the surface of a molded article made of a suitable base material and polymerizing it. Alternatively, the entire molded product may be formed only by using the above-mentioned polyfunctional monomer as a main component. When a base material is used, it is desirable that the base material be transparent enough to recognize a transmitted image, but there is no particular limitation. As the base material, an organic material (particularly an organic polymer material) is preferable. However, a composite material of an inorganic material and an organic material can also be used as the base material. Examples of the organic material include acrylic resin, vinyl chloride resin, polycarbonate resin, polyester resin and the like. Further, in the method of coating and polymerizing the polyfunctional monomer as described on the surface of the substrate, the thickness of the polymer layer on the surface is preferably 1 μm or more, and more preferably 3 μm or more. However, as described above, this base material is not always necessary, and the entire molded product is a polyfunctional monomer (a polyfunctional monomer having two or more (meth) acryloyloxy groups in one molecule). It may be composed of a polymer of

Next, the surface layer portion formed by polymerization of the polyfunctional monomer is irradiated with ultraviolet rays having a wavelength of 300 nm or less. This ultraviolet ray may be carried out by appropriately selecting a wavelength range and an irradiation time having energy enough to cut a part of the cross-linked structure of the polymer. The binding energy of the crosslinked structure of the polymer cannot be unconditionally specified because it depends on the composition of the polymer, but ultraviolet rays that impart energy of about 4 eV or more are desirable. The wavelength range with this energy is 3
It is not more than 00 nm. It should be noted that the acidic groups are not sufficiently generated only by performing ultraviolet irradiation. Then, the UV-irradiated portion is subjected to normal alkali treatment, that is, immersion in an alkaline aqueous solution. By this alkali treatment, an acidic group is generated in the surface layer portion in association with the above-mentioned action of ultraviolet irradiation. Examples of the alkaline aqueous solution used for the alkaline treatment include an aqueous solution of sodium hydroxide, potassium hydroxide and the like, and an alkaline aqueous solution in which various solvents such as alcohol are further added. The conditions for alkaline treatment are
UV irradiation amount, composition of UV irradiation site, form of molded product,
It cannot be specified unconditionally because it depends on the desired performance, but when using sodium hydroxide, for example,
It is desirable to use as an aqueous solution having a concentration of 0.1 to 50% by weight, more preferably 1 to 30% by weight.
The temperature of the alkali treatment is 0 to 100 ° C, preferably 20 to 80 ° C. Alkaline treatment time is 0.01
~ 100 hours, preferably 0.1-10 hours.

As a result of the above-mentioned ultraviolet irradiation and alkali treatment, 0.02 μmol / cm ² or more of acidic groups are usually produced on the surface of the molded product. From the infrared reflection spectrum of the surface of the molded product in which the acidic group was generated, COO ^{− at} 1570 cm ^−1.
Absorption by ions was observed. From this result, the acidic group is a COOH group or OH generated by hydrolysis of the ester bond.
Presumed to be the basis. In the present invention, the value of the content of the acidic group is represented by the number of moles (μmol / cm ² ) of the basic dye that can be absorbed per unit area of the surface of the molded product. This value is a value obtained by the following method. (1) 0.1 N sodium acetate buffer (PH4.
Create 5). (2) A solution having a methyl violet concentration of 1.0 g / l is prepared based on the buffer solution of (1). (3) A 50 × 50 mm ² molded product is immersed in this solution for 72 hours. (Temperature 25 ° C.) (4) The molded product is taken out and washed with water. (5) Remove water from the molded product after washing with water. (6) The dye is extracted and dissolved by immersing the molded product in an N, N-dimethylformamide solution for 24 hours. (7) The absorbance of the dye extract is measured using 587 nm light. (8) The calibration curve of the dye concentration is obtained from the dye solution dissolved in N, N-dimethylformamide in advance, and the basic dye concentration per unit area of the molded product is calculated.

The value of the content of acidic groups of the present invention (0.02 μ
mol / cm ² or more) means the binding capacity at the surface. In the present invention, the acidic groups are contained appropriately only in the surface layer portion of the polymer layer, the acidic groups are not much contained in the inner side, and the acidic groups are concentrated on the surface side. It is presumed that this acidic group reacts with the epoxy group of the silicon compound (A) to form a chemical bond. Therefore, the upper layer of the polymer layer has a function of chemically bonding the acidic group and the silicon compound (A), and the lower layer of the polymer maintains the crosslink density as it was when the polymer layer was formed. By virtue of these two characteristics, a molded product having extremely good hardness and durability is obtained. The thickness of the layer containing the acidic group is 1 from the outermost surface to the inside.
It is desirable to be within μm. If the thickness of the layer containing an acidic group exceeds 1 μm, the required hardness may not be obtained in some cases. Further, the lower limit of the thickness of the layer cannot be unconditionally specified because it is influenced by the relationship such as the content of the acidic group, but it is generally about 0.01 μm.

Instead of this treatment of the present invention in which ultraviolet irradiation and alkali treatment are successively performed, two or more conventional acidic group introduction methods (plasma treatment, light irradiation graft polymerization, chromium treatment, etc.) are used in one molecule. Even when applied to the polymer of the polyfunctional monomer having a (meth) acryloyloxy group, it is difficult to obtain good results in terms of the amount of acidic groups, hardness, and process easiness. The molded product after the alkali treatment is usually washed with appropriate water. Moreover, you may neutralize and wash with an inorganic acid or an organic acid as needed.

Then, the following general formula (A) X _a Si (OY) _4-a (A) (where X is an organic functional group Y containing an epoxy group, hydrocarbon group a is an integer of 1 to 3) The silica-based polymer obtained by hydrolyzing and polycondensing a silicon compound represented by the formula (1) is subjected to hydrolysis and polycondensation in the presence of a perchloric acid compound, water, and an organic solvent to form an epoxy group. By chemically reacting acidic groups, the surface of the molded product is coated and laminated. Examples of the silicon compound represented by the general formula (A) include glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, β-glycidoxyethyltriethoxysilane, and γ-glycidoxypropyltrimethoxysilane. , Γ-glycidoxypropyltriethoxysilane, glycidoxymethyl (methyl) dimethoxysilane, glycidoxymethyl (ethyl) dimethoxysilane, β-glycidoxyethyl (methyl) dimethoxysilane, β-glycidoxyethyl ( Examples thereof include methyl) dimethoxysilane, γ-glycidoxypropyl (methyl) dimethoxysilane, and γ-glycidoxypropyl (ethyl) dimethoxysilane.

To carry out the hydrolysis and polycondensation reaction of these silicon compounds, stirring is carried out in the presence of a reaction catalyst, water and an organic solvent at a temperature from room temperature to the reflux temperature for about 1 to 10 hours. water,
When the silicon compound (A) is dissolved in a mixed solvent of organic solvents to be hydrolyzed and polycondensed to form a silica-based polymer, it is necessary to control the PH value of the solvent. JDMiller,
H. Ishida reference (Macromolecules vol.17 1659 (1984))
According to the report, strong acidity (PH1-3), strong alkalinity (PH1)
1 to 14), since the OY group in the silicon compound (A) shifts to the polycondensation reaction while the hydrolysis is incomplete, the silica polymer in the solution has a one-dimensional polymer chain and has a relatively low molecular weight. It becomes a thing. In the vicinity of neutrality (PH7 to 9), the hydrolysis of the OY group is completely performed and then the condensation reaction rapidly occurs, and the silica-based polymer in the solution becomes a polymer having a three-dimensional polymer chain. .. According to our examination, strong acidity (PH1 to 3),
The generated particle size is small and does not cloud, but it is near neutral (PH7
In Nos. 9 to 9), the produced particle size is large and the result is likely to become cloudy. In the extreme case a precipitate formed.

A reaction catalyst is used to control such hydrolysis and polycondensation reaction according to the PH value. As the reaction catalyst, an organic acid, an inorganic acid, an organic base, an inorganic base, or a buffer solution is used. To set the PH value, it is necessary to find suitable conditions in consideration of the stability of the solution and the molecular weight of the silica-based polymer. In our study, PH5-6 is considered desirable. Further, it is desirable that the amount of water to be added be not less than the molar equivalent required for the hydrolysis reaction.

Examples of the organic solvent include alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol, ketones such as acetone and methyl ethyl ketone, and ethers such as tetrahydrofuran. The perchloric acid compound serves as a catalyst for a chemical reaction between an epoxy group contained in a silica-based polymer obtained by hydrolysis and polycondensation and an acidic group (-COOH group, -OH group) on the surface layer of a molded article. use. This includes magnesium perchlorate, ammonium perchlorate, potassium perchlorate,
Sodium perchlorate, perchloric acid, zinc perchlorate, aluminum perchlorate, etc. can be used.

As a method for applying the coating composition used in the present invention to the surface layer of a molded article, spray coating, spin coating, dip coating and the like can be adopted, but workability, smoothness of the coating, etc. From the viewpoint, dip coating is preferable, and when the shape of the molded product is complicated, spray coating is preferable. The coating amount of the coating is such that the thickness of the cured coating is 1 to 30 μm, preferably 1 to 10 μm. When the film thickness of the cured film is less than 1 μm, sufficient surface hardness and abrasion resistance cannot be obtained, and when it exceeds 30 μm, the adhesion to the base material may be deteriorated or the film may be easily cracked. To do. Heating to further polymerize and cure the silica-based polymer applied to the surface layer of the molded product, and to chemically react the epoxy group of the silica-based polymer with the acidic group (-COOH group, -OH group) of the surface layer of the molded product. I do. As the heating conditions, for example, conditions of 100 to 130 ° C. for 10 minutes to 10 hours in an oven can be adopted.

[0020]

EXAMPLES The present invention will be described in more detail with reference to Examples below. Example 1 10% by weight of dipentaerythritol hexaacrylate, 20% by weight of equimolar condensate of succinic acid / trimethylolethane / acrylic acid, tetrahydrofurfuryl acrylate A solution consisting of 5% by weight, 1.2% by weight of a photoinitiator (Darocur 1173 (manufactured by Merck)), 34% by weight of isopropanol, and 20% by weight of toluene was prepared.
A 2 mm-thick polymethylmethacrylate resin plate was immersed in this solution. Then, the film was slowly pulled up at a speed of 0.2 cm / sec to form a film on the surface of the resin plate. Then, this was kept at 35 ° C., and irradiation was performed at a dose of 840 mJ / cm ² using a high pressure mercury lamp having a center wavelength of 365 nm set at a distance of 15 cm from both sides of the resin plate. As a result, a cured film having a thickness of 3.5 μm was obtained on the surface of the resin plate. The pencil hardness (JIS K5400) of the resin plate on which this cured film was formed was 5H.

Irradiation was performed from above the resin plate on which the cured film was formed, using a low pressure mercury lamp having a central wavelength of 254 nm at an irradiation dose of 1300 mJ / cm ² . The acidic group on the surface layer of the resin plate after irradiation was measured by the basic dye methyl violet, and was 0.012 μm.
It was ol / cm ² . Furthermore, the resin plate is 20% by weight
Immersed in an aqueous sodium hydroxide solution at room temperature for 3 hours, washed with water, dried, and then immersed in a 0.05% by weight aqueous solution of sulfuric acid at room temperature
It was soaked in water, washed with water, and dried. The acid groups of the resin plate after the alkali treatment increased to 0.05 μmol / cm ² . Next, the following compositions were mixed, stirred at room temperature (20 ° C.) for 2 hours, and then allowed to stand for a day and night to obtain a coating solution. 1. γ-glycidoxypropyltrimethoxysilane 100.4 parts by weight 1. Isopropyl alcohol 278.3 parts by weight 3. 0.1N acetic acid / 0.1N sodium acetate 22.9 parts by weight (PH 5 buffer solution) 4. Magnesium perchlorate 2.0 parts by weight This solution was pulled up onto the resin plate having an acidic group on the surface layer described above at a speed of 100 cm / min. Dip coat with 1
The reaction was carried out at 05 ° C for 3 hours to form a cured film. The evaluation results of the physical properties of this cured film are shown in Tables 1 and 2.

The evaluation was carried out by the following method. Evaluation method 1. Surface hardness (wear resistance) While pressing a wear wheel (CS-17) manufactured by Taber Co., Ltd. under a constant load against the surface of the sample fixed to the rotary table, the sample was set to 20.
The sample was rotated 0 times and the abrasion of the sample surface was visually observed. 2. Adhesion 11 pieces each in the vertical and horizontal directions with a cutter knife on the sample surface
Make 100 squares by making scratches at 1.5 mm intervals, press cellophane tape 25 mm width (made by Nichiban) against the squares, and peel off rapidly. The number of squares remaining on the sample surface for 100 squares was used as an index of adhesion. 3. Hot water test After soaking in water at 80 ° C. for 20 hours, the adhesion and appearance were examined.

Comparative Examples 1 to 3 In Comparative Example 1, 1.5 mm ordinary window glass was used instead of the resin plate having an acidic group on the surface in the examples.
In Comparative Examples 2 and 3, a surface-hardened acrylic resin (trade name: Acrylite MR, manufactured by Mitsubishi Rayon) was used instead of the resin plate having an acidic group on the surface in the examples. The evaluation results of the physical properties of this cured film are shown in Tables 1 and 2. Table 1. Surface hardness (wear resistance)

[0024]

[Table 1] Note: ○; Slight scratches are visible, but transparency is maintained. △;
Scratches and reduced transparency. ×; severely scratched,
There is no transparency at all. Table 2. durability

[Table 2]

[0025]

As described above, the coated molded article obtained by the present invention is excellent in surface hardness, adhesion and durability. In particular, this molded product has (-Si-O-Si
-) Since it has a cross-linked structure cured film of _n , it has extremely excellent surface hardness. Further, since the present invention is a method which can be manufactured by simple steps and inexpensive equipment, it is advantageous to obtain a molded product having excellent surface hardness.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yukio Kobayashi 4-chome, Sunadabashi, Higashi-ku, Nagoya, Aichi Prefecture 60-1 Mitsubishi Rayon Co., Ltd. Product Development Laboratory (72) Inventor, Yuji Akagi 4-chome, Sunadabashi, Higashi-ku, Nagoya, Aichi No. 60 Mitsubishi Rayon Co., Ltd. Product Development Laboratory

Claims (2)

[Claims] 1. A polymer having a structural unit derived from a polyfunctional monomer having two or more (meth) acryloyloxy groups in one molecule as a main constitutional unit in at least its surface layer portion, and the surface layer portion. 0.02 μmol / c on the surface of
A molded article having m ² or more acidic groups, characterized in that a silica-based polymer obtained by polycondensing a silicon compound represented by the general formula (A) is laminated on the acidic groups. object. X _a Si (OY) _4-a (A) (In the formula, X is an organic functional group Y containing an epoxy group,
The hydrocarbon group a represents an integer of 1 to 3. ) 2. A molded product having a polymer having a structural unit derived from a polyfunctional monomer having two or more (meth) acryloyloxy groups in one molecule as a main constituent unit at least in its surface layer portion. Irradiation with ultraviolet rays having a wavelength of 300 nm or less, alkali treatment is performed to generate 0.02 μmol / cm ² or more of acidic groups in the surface layer portion of the molded article, and then the compound represented by the general formula (A) according to claim 1 is used. A method for producing a molded article, which comprises treating with a silicon compound as described above.