JP5564901B2 - Primer layer forming coating solution, primer layer and highly durable UV cut plastic substrate - Google Patents

Description

  The present invention provides a highly durable UV-cut plastic substrate having a transparent plastic substrate excellent in durability, a primer layer formed on the transparent plastic substrate, and a hard coat layer formed on the primer layer. In particular, the present invention relates to a primer layer forming coating solution for forming a primer layer, a primer layer obtained by using this coating solution, and a highly durable UV-cut plastic substrate having the primer layer.

  Transparent plastic base materials such as polycarbonate resin are lightweight and excellent in transparency, impact resistance, and the like, and therefore are used as lighting materials for vehicles and buildings as members that replace glass. However, since it is inferior in practical properties such as scratch resistance and weather resistance as compared with glass, improvement in surface properties is required.

  As means for improving the weather resistance of transparent plastic substrates, polyorganosiloxane-based (silicone-based), melamine-based thermosetting resins, etc., or polyfunctional acrylic-based photocurable resins can be used. A coating method has been proposed, and among them, a hard coat material using a silicone-based thermosetting resin is applied in glazing applications for vehicles that require high wear resistance.

  However, silicone hard coat materials have been a major problem in the past because of their poor adhesion to plastic substrates. For this reason, generally, a method of modifying the surface of a plastic substrate by improving the adhesion by interposing a primer layer such as an acrylic resin coating between the plastic substrate and the silicone-based hard coat layer Has been adopted.

  However, in the article coated with the silicone hard coat layer through the primer layer, the primer layer is decomposed and deteriorated by ultraviolet rays irradiated from sunlight when exposed to the outdoors for a long time, and the entire primer layer shrinks in volume. As a result, microcracks are generated in the hard coat of the upper layer, and peeling at any of the interfaces of the transparent plastic substrate / primer layer / hard coat layer is known to have poor durability. Yes.

  Therefore, as a method for producing a transparent plastic substrate having both weather resistance and scratch resistance, JP-A-56-92059 (Patent Document 1), JP-A-1-149878 (Patent Document 2), and JP-A-Hei 3 No. 6282 (Patent Document 3) and the like propose a method of adding an organic ultraviolet absorber to the primer layer.

  However, when an organic ultraviolet absorber is added to the primer layer, there have been problems such as whitening of the film and deterioration of adhesion due to bleeding out of the organic ultraviolet absorber due to long-term outdoor exposure.

  On the other hand, there is a method in which an organic ultraviolet absorber is contained in the silicone hard coat layer. However, in this case, there is a problem that a large amount of the ultraviolet absorber cannot be added from the viewpoint of scratch resistance.

  For this reason, Japanese Patent Application Laid-Open No. 11-58654 (Patent Document 4) proposes a method in which an organic ultraviolet absorber and a light stabilizer are distributed and contained in both the hard coat layer and the primer layer. However, when a large amount of the organic ultraviolet absorber is contained to such an extent that the deterioration of the primer layer can be completely prevented, there is a problem that the mechanical strength of the hard coat layer and the primer layer is surely lowered.

  Furthermore, organic UV absorbers are excellent in compatibility with organic resins and solvents, but the compounds themselves that make up organic UV absorbers are easily decomposed and deteriorated by wet heat and UV rays. ) In many cases, the function cannot be imparted for a long time, and the weather resistance of the surface-coated plastic substrate itself is limited to about 10 years when exposed outdoors. In addition, some benzotriazole ultraviolet absorbers have restrictions on use due to concerns about safety to the human body.

  Under such circumstances, particularly in the construction and automobile fields where high durability is required, a surface-coated high-performance plastic substrate, particularly a surface using an inorganic ultraviolet absorber that hardly causes the above-described problems. There is a need for a coated plastic substrate.

  Here, zinc oxide, titanium oxide, cerium oxide, etc. are widely known as representative examples of inorganic ultraviolet absorbers having a transparent wavelength region with respect to visible light (approximately 380 to 780 nm). Yes. However, the lifetime of these inorganic ultraviolet absorbers per se with respect to ultraviolet irradiation is semi-permanent, but many exhibit strong photocatalytic activity, which promotes oxidative degradation degradation of the organic resin binder that is contacted by ultraviolet irradiation, such as choking. It may cause product trouble. For this reason, in order to apply and apply the inorganic ultraviolet absorber to the surface coating material, it is necessary to separately suppress the photocatalytic action on the surface of the inorganic ultraviolet absorber by surface treatment of the inorganic ultraviolet absorber itself. .

  Therefore, in order to suppress the photocatalytic action on the surface of the inorganic ultraviolet absorbent material, a hydrolyzable silane monomer such as a silane coupling agent, or as disclosed in JP 2002-362925 A (Patent Document 5). There has been proposed a method of forming a polysiloxane film on the surface of oxide particles such as zinc oxide using methylhydrogenpolysiloxane which is a kind of reactive silicone oil.

  For example, titanium oxide particles having a polysiloxane film used in cosmetics or the like are directly mixed with titanium oxide particle powder and reactive silicone oil, or once dispersed in a solvent, It can be obtained by mixing the dispersion and reactive silicone oil, removing the solvent, and then drying by heating. In addition, when applied to a daylighting material application such as a window glass unlike a cosmetic application, the product base material is required to have high transparency without cloudiness. That is, in the matrix in which the particles are dispersed, it is necessary to maintain the dispersibility of the particles at a very high level, and the surface treatment technology of the inorganic ultraviolet absorber suppresses the aggregation of the inorganic ultraviolet absorber particles. At the same time, two aspects of sufficiently suppressing the photocatalytic activity are required. For this reason, generally, a method of finely crushing oxide particles such as zinc oxide formed with the polysiloxane film obtained by the above-described method using a medium stirring mill or the like is employed. It was done.

  However, as a result of studies by the present inventors, the following problems have been clarified.

  When forming a film on the surface of oxide particles, which are inorganic UV absorbers, using hydrolyzable silane monomers, hydrolyzable silane monomers are hydrolyzed and polycondensed by the sol-gel method to obtain oxide particle surfaces. A polysiloxane film is formed. However, in order to make the hydrolysis reaction proceed quickly, an acid catalyst such as hydrochloric acid or nitric acid, or an alkali catalyst such as sodium hydroxide, potassium hydroxide, or ammonia and water are required. The oxide particles are likely to aggregate due to pH fluctuations, and the aggregated oxide particles have a problem that the silane monomer is difficult to uniformly contact the individual oxide particles.

  In addition, condensation between surplus silane monomers easily occurs in the course of the reaction, and the generated oligomer reacts across a plurality of oxide particles, resulting in a coarse and strong condensation cluster interposing a silica component during solvent removal and drying. The problem that is easily formed occurs.

  In addition, since the mechanical strength of the coating formed on the oxide particles is low and the coating damage in the subsequent process such as crushing / dispersing treatment is large, as a result, the surface of the oxide particles such as zinc oxide is partially exposed. As a result, it became clear that it was difficult to obtain a reproducible effect.

  On the other hand, a reactive silicone oil as disclosed in Patent Document 5 has a structure in which a linear polysiloxane is a main chain, and a side chain and part of both ends are substituted with reactive groups. Yes. And since the reactive silicone oil is a high molecular weight substance, for example, it is easy to wet with respect to the oxide particle surface such as zinc oxide, and a highly active group such as Si-H can be introduced in a stable state. There is a merit that the reactivity to is high. However, since the reactive silicone oil is in the form of a series long chain, the influence of the steric factor is great, and the content of reactive groups present in the molecule is low, so that self-condensation is difficult. In addition, since it is difficult to form a three-dimensional bond between polymers, the film-forming property is low, and the surface of oxide particles such as zinc oxide is partially exposed due to film damage during pulverization treatment. There were problems such as low stability and low mechanical strength.

  Under such technical background, the present inventors have already proposed a method for producing surface-treated zinc oxide fine particles in which the photocatalytic action on the surface of the zinc oxide fine particles is suppressed (Patent Document 6).

  That is, this production method uses a silicone resin in place of the above-described reactive silicone oil and hydrolyzable silane monomer, and has a dispersion in which fine zinc oxide particles are dispersed in a solvent and at least one having a polysiloxane bond. A mixed solution containing the surface-treated zinc oxide fine particle precursor in which the above silicon atom is mixed with a silicone resin having a silanol group and / or an alkoxysilyl group to adsorb the silicone resin on the surface of the zinc oxide fine particle, and the above solvent And a first step of producing a dry solid by heat-treating the mixed solution to dryness, and a second step of producing surface-treated zinc oxide fine particles by crushing the dry solid.

  And since the silicone resin used in this method contains much more alkoxysilyl groups and silanol groups in the molecule than the reactive silicone oil, it has high self-condensation and excellent film-forming properties. In addition, there is no need to add an acidic (or basic) catalyst or water to promote the hydrolysis / polycondensation reaction unlike the hydrolyzable silane monomer, so that the pH change of the system is small during surface treatment. It does not impair the dispersibility of the zinc fine particles. For this reason, it becomes possible to apply a uniform and highly reproducible coating treatment to the surface of individual zinc oxide particles. Furthermore, silicone resins can be applied to cured coatings by introducing methyl groups or phenyl groups into the molecule. Since flexibility is imparted, film damage in the second step such as crushing / dispersing can be suppressed. Therefore, according to the method described in Patent Document 6, it is possible to obtain uniform surface-treated zinc oxide fine particles in which the surface of the zinc oxide fine particles can be uniformly coated with little damage and the photocatalytic action is suppressed. .

  By the way, the above-mentioned wet surface treatment method using a reactive silicone oil, a hydrolyzable silane monomer, etc. including the manufacturing method of the surface treatment zinc oxide fine particle described in the said patent document 6 is (1) Raw material grinding | pulverization process, Each process such as (2) surface treatment process, (3) solvent removal / drying process, and (4) redispersion process is necessary, and the treatment process is complicated, resulting in problems in manufacturing cost and productivity.

  In particular, it is industrially difficult to apply the above-described conventional surface treatment method to inorganic ultraviolet absorbers in the paint and plastics industry, where the market price has been established with inexpensive organic ultraviolet absorbers. I can say that.

  That is, in a transparent plastic substrate having a primer layer formed on a transparent plastic substrate and a hard coat layer formed on the primer layer, while maintaining practical transparency and substrate adhesion, There is no known primer composition that can completely suppress cracking and peeling of the hard coat layer by outdoor exposure. In particular, in the method of adding an ultraviolet absorber to a primer layer, if a surface treatment technology for an inorganic ultraviolet absorber is established, which is inexpensive and industrial, stable performance as a primer layer forming composition can be ensured. It becomes easy and the durability of the transparent plastic substrate itself can be improved.

JP 56-92059 A JP-A-1-149878 Japanese Patent Laid-Open No. 3-6282 JP-A-11-58654 JP 2002-362925 A JP 2009-120721 A

  The present invention has been made paying attention to such problems, and the problem is that it has excellent ultraviolet absorption (shielding) ability and maintains good adhesion to a transparent plastic substrate and a hard coat layer. And providing a primer layer-forming coating solution (composition) for forming a primer layer that dramatically improves durability outdoors, and a primer layer formed using this coating solution, and further transparent An object of the present invention is to provide a highly durable UV cut plastic base material having a hard coat layer formed on a plastic base material through a primer layer formed using a primer layer forming coating solution by an inexpensive and industrial production method.

  Therefore, in order to achieve the above-mentioned problems, the present inventors have conducted intensive studies. As a result, the silicone resin, which is a silane compound, is introduced into a mill base composed of zinc oxide raw material powder and a solvent, and zinc oxide is used using a wet medium stirring mill. First, a coating solution precursor for forming a primer layer containing the coated zinc oxide fine particles and the solvent without removing the above-mentioned solvent is prepared while the raw material powder is pulverized and the surface of the pulverized zinc oxide fine particles is coated with a silicone resin. It was found that the primer layer forming coating liquid (composition) can be easily obtained by preparing and mixing an acrylic resin binder with the primer layer forming coating liquid precursor. Furthermore, the primer layer formed by applying this primer layer-forming coating solution (composition) on a transparent plastic substrate and heat-curing has excellent ultraviolet absorption (shielding) ability and transparency. The resulting primer layer maintains good adhesion to the transparent plastic substrate and hard coat layer, making the highly durable UV-cut plastic substrate excellent in outdoor durability inexpensive and industrial It came to be found that it can be provided by a typical manufacturing method.

That is, the invention according to claim 1
Primer for forming the above-mentioned primer layer of a highly durable UV-cut plastic substrate having a transparent plastic substrate, a primer layer formed on the transparent plastic substrate, and a hard coat layer formed on the primer layer In the coating liquid for layer formation,
A silane compound is charged into a mill base composed of zinc oxide raw material powder and a solvent, and the zinc oxide raw material powder is pulverized and the surface of the pulverized zinc oxide fine particles is coated with the silane compound using a wet medium stirring mill. A primer layer-forming coating solution precursor containing a coating-treated zinc oxide fine particle having a primary particle diameter of 100 nm or less and a solvent prepared without removal, and an acrylic system mixed with the primer layer-forming coating solution precursor A polysiloxane comprising a resin binder and consisting of repeating siloxane bonds (Si-O-Si) as a main chain (however, each silicon atom constituting the main chain is composed of four oxygen atoms, the Q unit structure coupled to the conditions), and one or more molecular end alkoxysilyl group (Si-oR) and / or silanol groups (Si- Blocked with H), characterized in that the silane compound is constituted by a silicone resin having a hydrocarbon group and / or a phenyl group having 1 to 18 carbon atoms in the molecule as the organic substituent.

The invention according to claim 2
In the primer layer forming coating solution according to the invention of claim 1,
The silicone resin contains 10 to 300 parts by weight with respect to 100 parts by weight of the zinc oxide fine particles,
The invention according to claim 3
In the primer layer forming coating solution according to the invention of claim 1,
The acrylic resin binder is a (meth) acrylic resin obtained by polymerizing an alkyl acrylate monomer or an alkyl methacrylate monomer,
The invention according to claim 4
In the primer layer forming coating solution according to any one of claims 1 to 3,
The zinc oxide fine particles contain 30 to 500 parts by weight with respect to 100 parts by weight of the acrylic resin binder,
The invention according to claim 5
In the primer layer forming coating solution according to any one of claims 1 to 4,
Characterized in that it contains one or more organic ultraviolet absorbers selected from benzophenone derivatives, benzotriazole derivatives, triazine derivatives and cyanoacrylate derivatives,
The invention according to claim 6
In the primer layer forming coating solution according to any one of claims 1 to 5,
It contains one or more hindered amine light stabilizers selected from 2,2,6,6-tetramethylpiperidine derivatives and 1,2,2,6,6-pentamethyl-4-piperidine derivatives. Is.

Next, the invention according to claim 7 provides:
In the primer layer formed on the transparent plastic substrate,
It is obtained by heating and curing a coating layer formed by coating the primer layer forming coating solution according to any one of claims 1 to 6 on a transparent plastic substrate,
The invention according to claim 8 provides:
In the primer layer according to the invention of claim 7,
The haze value of the primer layer alone is 1.5% or less when the ultraviolet transmittance is 10% or less.

Furthermore, the invention according to claim 9 is
In high durability UV cut plastic substrate,
A transparent plastic substrate, a primer layer having a film thickness of 1 to 20 μm formed on the transparent plastic substrate using the primer layer forming coating solution according to claim 1, and a primer layer Characterized by comprising a hard cord layer having a thickness of 1 to 20 μm,
The invention according to claim 10 is:
In the high durability UV cut plastic substrate according to the invention of claim 9,
The hard coat layer is a silicone resin,
The invention according to claim 11 is:
In the high durability UV cut plastic substrate according to the invention of claim 9,
The transparent plastic base material is polymethyl methacrylate resin, polycarbonate resin, polystyrene resin, polyester resin, polyacetal resin, polysulfone resin, polyether sulfone resin, polyvinyl chloride resin, polyvinylidene chloride resin, epoxy resin, unsaturated polyester resin. , A polyurethane resin, a diallyl phthalate resin, a diethylene glycol bisallyl carbonate resin, an acetyl cellulose resin, a sulfur-containing urethane resin, or a crosslinked (meth) acrylic resin,
The invention according to claim 12
In the high durability UV cut plastic substrate according to the invention of claim 9,
The transparent plastic substrate is a polycarbonate resin.

  The primer layer-forming coating solution according to the present invention is prepared by adding a silane compound to a mill base composed of a zinc oxide raw material powder and a solvent and pulverizing the zinc oxide raw material powder using a wet medium stirring mill, The coating solution precursor for forming the primer layer containing the coating-treated zinc oxide fine particles and the solvent prepared without coating the silane compound and without removing the solvent, and mixed with the coating solution precursor for forming the primer layer The main component is comprised with the acrylic resin binder.

  And according to this invention, unlike the conventional wet surface treatment method with respect to the zinc oxide fine particle surface, inorganic type ultraviolet absorption is not required without said (3) solvent removal and drying process, (4) redispersion process, etc. The coating liquid for primer layer formation to which the agent is applied can be obtained, so that the market price has been established with inexpensive organic UV absorbers, and even in the paint and plastics industry, it is inexpensive to apply inorganic UV absorbers. It can be used as a primer layer forming coating solution.

  Furthermore, the primer layer of the present invention formed using the above-mentioned primer layer forming coating solution has excellent ultraviolet absorption (shielding) ability and transparency, and is excellent as a transparent plastic substrate and a hard coat layer. Therefore, it is also possible to provide a highly durable UV-cut plastic base material having excellent outdoor durability at low cost.

  Next, embodiments according to the present invention will be specifically described.

First, the primer layer forming coating solution according to the present invention is prepared by adding a silane compound to a mill base composed of a zinc oxide raw material powder and a solvent, and pulverizing and pulverizing the zinc oxide raw material powder using a wet medium stirring mill. A coating solution precursor for forming a primer layer containing a coating-treated zinc oxide fine particle having a primary particle diameter of 100 nm or less and a solvent prepared by performing coating treatment with a silane compound on the surface of the fine particle and without removing the solvent, and and it contains an acrylic resin binder that is mixed in the primer layer forming coating liquid precursor, and a polysiloxane comprising repeating siloxane bond (Si-O-Si) backbone (however, constituting the main chain to each silicon atom with the proviso Q unit structure bonded to four oxygen atoms respectively), and one or more molecular end alkoxysilyl group ( i-OR) and / or silanol group (Si-OH), and the silane compound is a silicone resin having a hydrocarbon group having 1 to 18 carbon atoms and / or a phenyl group as an organic substituent in the molecule. It is configured.

  Hereinafter, (1) zinc oxide fine particles and production method thereof, (2) coated (surface) treated zinc oxide fine particles and production method thereof, (3) primer layer forming coating solution, and (4) primer layer forming coating solution are used. Each of the primer layer formation method, (5) hard coat layer, (6) transparent plastic substrate, and highly durable UV-cut plastic substrate will be described in detail below.

(1) Zinc oxide fine particles and production method thereof Ultraviolet light is classified according to wavelength region into UVC light of 280 nm or less, UVB light of 280 to 320 nm, and UVA light of 320 to 400 nm. In the highly durable UV-cut plastic substrate according to the present invention, the UVA light occupies 90% of the ultraviolet light reaching the ground.

  And as an inorganic material which has a transparent wavelength range with respect to visible light (380-780 nm) and absorbs ultraviolet light, the above-mentioned titanium oxide, cerium oxide, etc. other than the said zinc oxide are known. Among them, zinc oxide has the feature that it can selectively absorb UVA light without greatly reducing the visible light transmittance because the absorption edge is on the longer wavelength side compared to titanium oxide, cerium oxide, and the like. doing.

  Zinc oxide is particularly suitable when used as a raw material for a transparent substrate because zinc oxide is excellent in visible light transparency with respect to ultraviolet light absorption properties, although the hiding power as a white pigment does not reach that of titanium oxide. The primary particle diameter of the zinc oxide fine particles needs to be 100 nm or less in order to avoid the light shielding phenomenon due to scattering, and is more preferably 50 nm or less. In this case, the particle diameter is remarkably small with respect to the wavelength of visible light (380 to 780 nm), and Mie or Rayleigh scattering formula is applied to light scattering. In general, the smaller the refractive index of the material, It is known that the smaller the particle size, the smaller the scattering intensity. In this respect, since zinc oxide has a refractive index lower than that of titanium oxide or the like, the intensity of scattered light when compared with the same particle diameter is smaller than that of titanium oxide or the like. That is, zinc oxide has a smaller tendency to scatter incident light than other inorganic transparent ultraviolet absorbers, and as a result, higher transparency can be obtained when dispersed in a resin binder or plastic.

  Next, a method for producing zinc oxide fine particles will be described with an example.

  First, zinc oxide crystals are hexagonal (wurtzite type), and zinc atoms and oxygen atoms are tetrahedrally coordinated with each other by four atoms, and this is a framework for developing various physical properties. And, the industrial production method of zinc oxide is roughly divided into a dry method in which molten zinc is steam-oxidized and a wet method in which basic zinc carbonate is made by adding a soda ash solution to a zinc sulfate aqueous solution. In the present invention, wet powder from which crystals with a finer particle diameter are obtained is used as a raw material. Specifically, a precipitate is generated from an aqueous zinc solution and an alkaline aqueous solution, and this is aged, and the precipitate is moistened with alcohol to start drying to obtain a zinc oxide fine particle precursor, and then the zinc oxide fine particle precursor. The body is fired into zinc oxide fine particles.

  Here, the zinc compound for preparing the zinc aqueous solution is not particularly limited, and examples thereof include zinc nitrate, zinc chloride, zinc acetate, and zinc sulfate. Nitrate is preferable because of easy removal of impurities.

  On the other hand, the alkaline aqueous solution is not particularly limited, and examples thereof include aqueous solutions of sodium hydroxide, potassium hydroxide, ammonium hydrogen carbonate, ammonia, and the like. The alkali concentration of sodium hydroxide or the like in the alkaline aqueous solution is preferably 1.0 to 1.5 times the chemical equivalent necessary for the zinc compound to become a hydroxide. This is because if the alkali is equal to or more than the chemical equivalent, the charged zinc compound can react, and if it is 1.5 times or less, the cleaning time for removing the residual alkali does not increase.

  Next, the formation and aging of the precipitate will be described.

  The precipitate is formed by dropping an aqueous solution of a zinc compound into an alkaline aqueous solution that is continuously stirred. By dropping the aqueous solution of the zinc compound into the alkaline aqueous solution, the supersaturation degree is instantaneously reached and a precipitate is generated, so that a precipitate of fine particles of zinc carbonate and zinc hydroxide carbonate having a uniform particle diameter is obtained. Precipitates of fine particles of zinc carbonate and zinc hydroxide carbonate with the same particle size as described above, whether an alkaline solution is dropped into an aqueous solution of zinc compound or a zinc compound solution and an alkaline solution are dropped in parallel It is difficult to get.

  Although the alkaline aqueous solution temperature at the time of the production | generation of a precipitate is not specifically limited, It is 50 degrees C or less, Preferably it is room temperature. The lower limit of the temperature of the alkaline aqueous solution is not determined, but if it is too low, a cooling device or the like is newly required. Therefore, it is preferable that the temperature is not required. The dropping time of the aqueous zinc compound solution in the alkaline aqueous solution is less than 30 minutes, preferably 20 minutes or less, more preferably 10 minutes or less from the viewpoint of productivity. After completion of the dropwise addition, aging is carried out with continuous stirring in order to make the system uniform. The aging temperature is the same as that during precipitation. The time for continuous stirring is not particularly limited, but is 30 minutes or less, preferably 15 minutes or less from the viewpoint of productivity.

  The precipitate obtained after the aging is washed by decantation, but is sufficiently washed until the conductivity of the washing liquid becomes 1 mS / cm or less. This is because a desired ultraviolet absorption (shielding) characteristic can be obtained if there are few impurities such as chlorine ions, nitrate ions, sulfate ions and acetate ions remaining in the fine particles. Therefore, it is preferable to sufficiently wash until the conductivity of the supernatant after washing becomes 1 mS / cm or less (corresponding to a residual impurity amount of 1.5% or less).

  Next, the washed precipitate is wet-treated with an alcohol solution to obtain a wet-processed product, and then the wet-processed product is dried to obtain a zinc oxide fine particle precursor. Then, the zinc oxide fine particle precursor is dried to obtain zinc oxide fine particles. By performing the wet treatment, aggregation of the zinc oxide fine particle precursor after drying can be avoided.

  The alcohol concentration of the alcohol solution is preferably 50% by mass or more. This is because if the alcohol concentration is 50% by mass or more, the zinc oxide fine particles can be prevented from becoming strong aggregates and exhibit excellent dispersibility.

  The alcohol solution used in the wet treatment will be described. Although the alcohol used for the said alcohol solution is not specifically limited, Alcohol which melt | dissolves in water and whose boiling point is 100 degrees C or less is preferable. Examples include methanol, ethanol, propanol, and tert-butyl alcohol.

  The wetting process will be described. The wet treatment may be performed by adding the filtered and washed precipitate into the alcohol solution and stirring, and the time and stirring speed at this time may be appropriately selected according to the treatment amount. The amount of the alcohol solution when the precipitate is put into the alcohol solution may be a liquid amount that can easily stir the precipitate and ensure fluidity. The agitation time and agitation speed are appropriately selected on the condition that the precipitate containing the part that has been partially aggregated during the filtration and washing described above is uniformly mixed in the alcohol solution until the aggregated part is eliminated.

  In the wet treatment, the temperature is usually room temperature, but if necessary, it is possible to carry out the heating while heating the alcohol so that the alcohol is not lost by evaporation. Preferably, by heating at a temperature equal to or lower than the boiling point of the alcohol, disappearance of the alcohol during the wet treatment can be avoided, and the loss of the effect of the wet treatment can be avoided. By maintaining the presence of alcohol during the wet treatment, the effect of the wet treatment is obtained, and the precipitate does not become a strong aggregate after drying, which is preferable.

  The drying of the wet processed product will be described. Drying conditions such as drying temperature and time are not particularly limited, and it is only necessary to start heat drying in a state where the wet processed product is wet with alcohol. After the wet treatment, the precipitate does not become a strong agglomerate even if heat drying is performed. Therefore, the drying conditions may be appropriately selected depending on the treatment amount of the wet treated product, the treatment apparatus, and the like.

By the drying treatment, a zinc oxide fine particle precursor subjected to a wet treatment can be obtained. The precursor is a mixed phase of ZnCO ₃ and Zn ₅ (OH) ₆ (CO ₃ ) ₂ and ZnCO ₃ (()) with respect to the (200) XRD peak intensity of Zn ₅ (OH) ₆ (CO ₃ ) ₂ 104) The ratio to the XRD peak intensity is 0.6 or more. In particular, the ratio of the ZnCO ₃ (104) XRD peak intensity to the (200) XRD peak intensity of Zn ₅ (OH) ₆ (CO ₃ ) ₂ is 0.6 or more. Satisfactory values are obtained in the crystallite size, specific surface area and average particle size of the above, and the ultraviolet absorber (shield) produced using the zinc oxide fine particles exhibits desired optical characteristics.

  On the other hand, as an alcohol solution used in the wet treatment, an alcohol solution containing at least one element selected from Si, Al, Zr, and Ti, less than 15% by weight in terms of oxide, is used as necessary. Also good. Preferred examples of the alcohol solution are the same as described above. By taking this configuration, one or more elements selected from Si, Al, Zr, and Ti are present independently in the vicinity of zinc oxide, and the grain growth of zinc oxide is suppressed during firing. . If the content of these elements in terms of oxide is less than 15% by weight, the content ratio of zinc oxide does not decrease, so that the ultraviolet absorption (shielding) characteristic is maintained and the hiding power is maintained.

  The dried zinc oxide precursor is baked to improve ultraviolet absorption (shielding) characteristics and hiding power. The calcination is performed in the atmosphere, in an inert gas such as nitrogen, argon, or helium, or in a mixed gas of the inert gas and a reducing gas such as hydrogen. The treatment temperature at this time is preferably lower than 350 ° C. and preferably 500 ° C. or lower from the viewpoint of desired ultraviolet absorption (shielding) characteristics. What is necessary is just to select the processing time at this time suitably according to the processing amount and baking temperature of a zinc oxide precursor.

Described above, according to the manufacturing method of the zinc oxide fine particles, the crystallite diameter of 17Nm～20nm, a specific surface area of less than ^{30m 2} / ^g~55m 2 / g, and an average particle diameter is 19nm~35nm Zinc oxide fine particles are obtained. However, the average particle diameter is a value obtained from d = 6 / ρ · S (d: particle diameter, ρ: true density, S: specific surface area).

(2) Coated (surface) -treated zinc oxide fine particles and method for producing the same Zinc oxide fine particles exhibit a stronger photocatalytic activity as the particle size becomes smaller. This may cause product troubles such as (Chalking, chalking). In order to apply the zinc oxide fine particles to the surface coating (coating) material and put it to practical use, it is necessary to suppress the catalytic action by surface treatment or the like.

  That is, the surface treatment technology for zinc oxide fine particles requires two aspects of suppressing the aggregation of the zinc oxide fine particles and at the same time sufficiently suppressing the photocatalytic activity as described above. The performance will be greatly affected.

  In addition, the non-desorbable integral blend method is employed for the coating (surface) treatment method of the zinc oxide fine particles according to the present invention. That is, a silane compound is introduced into a mill base composed of a zinc oxide raw material powder and a solvent, and the zinc oxide raw material powder is pulverized using a wet medium stirring mill and the surface of the pulverized zinc oxide fine particles is coated with the silane compound (surface) In addition to performing the treatment, a coating solution precursor for forming a primer layer containing a coating-treated zinc oxide fine particle having a primary particle diameter of 100 nm or less coated with a silane compound and a solvent without removing the solvent is obtained.

  In the coating (surface) treatment method according to the present invention, a solvent removal treatment for removing the solvent and drying (firing), which was an essential step in the conventional wet surface treatment method [(3) Solvent removal / drying step described above] And, it is possible to obtain the coating liquid precursor for forming the primer layer only in the above-mentioned one step without requiring the dispersion (disintegration) treatment of the coating (surface) treatment powder [(4) redispersion step described above]. Become. In addition, the solvent which concerns on the said mill base is not specifically limited, For example, various kinds of common solvents and organic solvents, such as alcohol, ether, ester, a ketone, an aromatic compound, can be used.

The silane compound applied to the zinc oxide fine particle coating (surface) treatment method according to the present invention is a silicone resin (silane oligomer) made of a silicone polymer having a polysiloxane bond, and a siloxane bond (Si—O—). A polysiloxane composed of repeating Si) as a main chain (provided that the Q unit structure in which each silicon atom constituting the main chain is bonded to four oxygen atoms), and one or more molecular terminals Is blocked with an alkoxysilyl group (Si-OR) and / or a silanol group (Si-OH) formed by hydrolysis of an alkoxysilyl group, and organic substitution of a hydrocarbon group having 1 to 18 carbon atoms and / or a phenyl group Examples are silicone resins that require high molecular weight molecules in the molecule as groups and have the molecular structures [1] and [2] shown below. That.

［但し、Ｒは、炭素原子数１〜１８のアルキル基またはフェニル基である。各末端基におけるＲは、分子中内において全て同じ基であっても、異なった基であってもよい。］

[However, R is a C1-C18 alkyl group or a phenyl group. R in each terminal group may be the same group or different groups in the molecule. ]

  Silicone resins, unlike linear silicone reactive silicone oils based on dimethylpolysiloxane, have alkoxysilyl groups and silanol groups in their molecules and are self-condensing, so they have film-forming properties. high. In addition, since it has a three-dimensionally crosslinked siloxane skeleton, rapid self-condensation is unlikely to occur, and it is acidic (or basic) to promote hydrolysis and polycondensation reactions like hydrolyzable silane monomers. Since there is no need to add a catalyst or water, the pH variation of the system is small during the surface treatment, and the dispersibility of the zinc oxide fine particles is not impaired, so the surface of each zinc oxide fine particle is uniformly and highly reproducible. (Surface) treatment is possible, and an excellent coating (surface) treatment effect can be obtained in inactivating the photocatalytic activity of the zinc oxide fine particles. In addition, by changing the molecular weight and the introduction rate of methyl and phenyl groups, which are organic substituents in the molecule, it is possible to increase compatibility with various solvents and resin media, and to adjust the polarity. It is also possible to function as an excellent polymer dispersant for zinc fine particles.

  The total weight of the silicone resin used for coating (surface) treatment with zinc oxide fine particles is particularly preferably 10 to 300 parts by weight with respect to 100 parts by weight of zinc oxide fine particles. That is, when the amount of the silicone resin is less than 10 parts by weight, the coating amount of the silicone resin may not be sufficient with respect to the surface of the zinc oxide fine particles, and it becomes difficult to sufficiently suppress the photocatalytic activity of the zinc oxide fine particles. This is because when contained in the layer, the organic resin binder or the resin base material may be oxidatively deteriorated to cause problems such as choking. In addition, the dispersion stability of the zinc oxide fine particles tends to be low, and sufficient transparency may not be imparted to the resulting primer layer. On the other hand, when the silicone resin exceeds 300 parts by weight, the silicone resin reacts across a plurality of zinc oxide fine particles or the condensation or aggregation of excess silicone resins easily occurs during the coating (surface) treatment. As a result, the zinc oxide fine particles cannot be highly dispersed, and it may be difficult to impart sufficient transparency to the resulting primer layer.

  Furthermore, the molecular weight of the silicone resin is preferably 100 to 100,000, more preferably 500 to 10,000. If the molecular weight is 100 or more, sufficient film-forming properties can be obtained, and if it is 100,000 or less, the viscosity does not become too high, and the efficiency and dispersibility of the zinc oxide raw material powder during the coating (surface) treatment process are improved. A decrease can be avoided.

(3) Primer layer forming coating solution The primer layer forming coating solution according to the present invention is a primer layer forming coating solution precursor containing a silicate-coated zinc oxide fine particle having a primary particle diameter of 100 nm or less and a solvent as described above. And an acrylic resin binder mixed in the primer layer forming coating solution precursor.

[A] (Meth) acrylic resin binder The primer layer-forming coating solution according to the present invention is one in which the silicate-coated zinc oxide fine particles are highly dispersed in a liquid medium. In addition, the primer layer forming coating liquid contains an organic binder resin in the liquid medium as a film-forming component in order to finally form a primer layer that is a solid medium on a plastic substrate. And as organic binder resin for paints, styrene resin, acrylic resin, cellulose derivative, urethane resin, melamine resin, epoxy resin, phenol resin, etc. are widely used and are selected according to the purpose as appropriate. Examples of the organic binder resin contained in the primer layer forming coating liquid according to the invention include dispersibility of the silicate-coated zinc oxide fine particles, adhesion to the plastic substrate and the upper hard coat material, transparency of the material itself and processing. In view of the properties and the like, a (meth) acrylic resin obtained by polymerizing an alkyl acrylate monomer or an alkyl methacrylate monomer is desirable.

  Further, the blending amount of the zinc oxide fine particles can be arbitrarily set according to the thickness of the primer layer, the required optical properties, and mechanical properties, but with respect to 100 parts by weight of the (meth) acrylic resin binder. It is preferably in the range of 30 to 500 parts by weight. If the blending amount of the zinc oxide fine particles is within the above range, the intended ultraviolet absorption characteristic (ultraviolet transmittance of 10% or less) can be achieved within a predetermined primer layer thickness (1 to 20 μm). In addition, it is possible to avoid agglomeration of the zinc oxide fine particles in the resin matrix, so that it is possible to maintain good transparency.

[B] Organic UV Absorbing Material The primer layer forming coating solution according to the present invention uses zinc oxide fine particles as the UV absorber, and the lifetime as the UV absorber is semi-permanent. It can be used. However, for the purpose of further enhancing the ultraviolet absorption (shielding) ability, an organic ultraviolet absorbing material selected from the following group can be appropriately blended in the primer layer forming coating solution. The organic UV-absorbing material is not particularly limited, but it is at least one selected from benzophenone derivatives, benzotriazole derivatives, triazine derivatives and cyanoacrylate derivatives from the viewpoint of availability and cost. Is desirable.

  As the organic ultraviolet absorbing material, specifically, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone, 2- (2-hydroxy- 5-methylphenyl) benzotriazole, 2- (2-hydroxy-5-t-octylphenyl) benzotriazole, 2- (2-hydroxy-3,5-di-t-butylphenyl) benzotriazole, 4- (2 -Acryloxyethoxy) -2-hydroxybenzophenone polymer, 2- (2-hydroxy-4-hexyloxyphenyl) -4,6-diphenyltriazine and the like can be exemplified. It is not limited.

[C] Hindered amine light stabilizer (HALS)
The primer layer forming coating solution according to the present invention suppresses ultraviolet deterioration of organic components such as an organic binder resin in the primer layer over a long period of time by using zinc oxide fine particles as an ultraviolet absorber. For the purpose of further extending the lifetime of the organic component, a hindered amine light stabilizer (HALS) can be blended in the primer layer forming coating solution.

  Examples of the hindered amine light stabilizer (HALS) include 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy. -1,2,2,6,6-pentamethylpiperidine, 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-1,2,2,6,6-pentamethylpiperidine Bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, bis (2,2,6,6- Tetramethyl-1-octoxypiperidinyl) sebacate, 4- {3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl Xy} -1- [2- {3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy} ethyl] -2,2,6,6-tetramethylpiperidine, bis (1,2 , 2,6,6-pentamethyl-4-piperidinyl) 2-butyl-2- (3,5-di-t-butyl-4-hydroxybenzyl) malonate, 8-acetyl-3-dodecyl-7,7,9 , 9-Tetramethyl-1,3,8-triazaspiro [4.5] decane-2,4-dione, tetrakis (2,2,6,6-tetramethyl-4-piperidinyl) 1,2,3,4 -Butanetetracarboxylate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidinyl) 1,2,3,4-butanetetracarboxylate, tridecyltris (2,2,6,6-tetra Methyl -Piperidinyl) 1,2,3,4-butanetetracarboxylate, tridecyltris (1,2,2,6,6-pentamethyl-4-piperidinyl) -1,2,3,4-butanetetracarboxylate, Ditridecyl bis (2,2,6,6-tetramethyl-4-piperidinyl) 1,2,3,4-butanetetracarboxylate, ditridecyl bis (1,2,2,6,6-pentamethyl-4- Piperidinyl) 1,2,3,4-butanetetracarboxylate, 3,9-bis [1,1-dimethyl-2- {tris (2,2,6,6-tetramethyl-4-piperidinyloxycarbonyl) ) Butylcarbonyloxy} ethyl] -2,4,8,10-tetraoxaspiro [5.5] undecane, 3,9-bis [1,1-dimethyl-2- {tris (1, 2,2,6,6-pentamethyl-4-piperidyloxycarbonyl) butylcarbonyloxy} ethyl] -2,4,8,10-tetraoxaspiro [5.5] undecane, 2,2,4,4-tetra Methyl-20- (β-lauryloxycarbonyl) -ethyl-7-oxa-3,20-diazadispiro [5.1.1.12] heneicosan-21-one, 2,4,6-tris {N-cyclohexyl- N- (2-oxo-3,3,5,5-tetramethylpiperazino) ethyl} -1,3,5-triazine and the like. Preferably, bis (2,2,6,6-tetramethyl-4-piperidinyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, bis (2,2,6, 6-tetramethyl-1-octyloxy-4-piperidinyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) 2-butyl- (3,5-di-t-butyl-4 -Hydroxybenzyl) malonate, 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro [4.5] decane-2,4-dione, 2,2,4 , 4-Tetramethyl-20- (β-lauryloxycarbonyl) -ethyl-7-oxa-3,20-diazadispiro [5.1.1.1.2] heneicosan-21-one, tetrakis (1,2,2 6,6-pentamethyl-4-piperidinyl) 1,2,3,4-butanetetracarboxylate, tridecyl tris (1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3 4-butanetetracarboxylate, 4- {3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy} -1- [2- {3- (3,5-di-t-butyl) -4-hydroxyphenyl) propionyloxy} ethyl] -2,2,6,6-tetramethylpiperidine, more preferably bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, Bis (2,2,6,6-tetramethyl-1-octyloxy-4-piperidinyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) 2-buty Ru- (3,5-di-t-butyl-4-hydroxybenzyl) malonate, 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro [4.5 Decane-2,4-dione, 2,2,4,4-tetramethyl-20- (β-lauryloxycarbonyl) -ethyl-7-oxa-3,20-diazadispiro [5.1.1.12] Heneicosan-21-one, tridecyl-tris (1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, 4- {3- (3,5- Di-t-butyl-4-hydroxyphenyl) propionyloxy} -1- [2- {3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy} ethyl] -2,2,6 , 6-Tetramethyl Piperidine, and the like. Moreover, these can use 1 type (s) or 2 or more types.

  More preferably, a hindered amine light stabilizer (HALS) selected from 2,2,6,6-tetramethylpiperidine derivatives or 1,2,2,6,6-pentamethyl-4-piperidine derivatives. There should be. In particular, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, or bis (1,2,2,6, 6-pentamethyl-4-piperidyl) sebacate is preferred in that it is excellent in solubility in (meth) acrylic resin binders and in the effect of suppressing deterioration due to radical oxidation.

[D] Other components The primer layer-forming coating solution according to the present invention is added to the silicate-coated zinc oxide fine particles, the acrylic resin binder, the organic ultraviolet absorbing material, and the hindered amine light stabilizer (HALS). Furthermore, it is possible to add a known additive, diluent, curing catalyst and the like. For example, water or an organic solvent can be used as the diluent, and examples of the organic solvent include alcohols, ketones, esters, ethers, and the like. Specifically, methanol, ethanol, isopropanol, isopropanol, and the like can be given. Examples include alcohols such as butanol, ketones such as methyl ethyl ketone and methyl isobutyl ketone, esters such as ethyl acetate and isobutyl acetate, aromatic compounds such as toluene and xylene, and mixed solvents thereof.

(4) Method for forming primer layer using primer layer forming coating solution The primer layer forming coating solution according to the present invention forms a coating layer (hard coat layer) with a silicone-based coating agent on a transparent plastic substrate. Used for the primer treatment.

  When the primer layer is formed on the transparent plastic substrate using the primer layer forming coating solution according to the present invention, the primer layer forming coating solution is spray coated, roll coated, dip coated on the transparent plastic substrate. It is possible to employ a method in which the binder resin is applied by an appropriate method such as spin coating and the coating layer is heated at room temperature to 150 ° C. for 10 minutes to 2 hours to cure the binder resin. The lower limit temperature, heating time, and heating atmosphere (including vacuum) are not particularly limited as long as the solvent evaporates and the coating layer (coating film) is cured. The film thickness of the primer layer is not particularly limited, but is preferably 1 to 20 μm, particularly preferably 1 to 10 μm, and more preferably 2 to 5 μm. When the film thickness is less than 1 μm, the amount of zinc oxide fine particles added to the resin binder is excessive in order to obtain predetermined optical characteristics (ultraviolet transmittance of 10% or less), and as a result, sufficient adhesion strength can be obtained. There are cases where it is impossible On the other hand, when the film thickness exceeds 20 μm, the increase in haze is increased, and cracks and peeling of the upper hard coat layer may easily occur due to curing shrinkage of the primer layer.

(5) Hard coat layer A highly durable UV-cut plastic substrate according to the present invention comprises a transparent plastic substrate, a primer layer formed on the transparent plastic substrate, and a hard coat formed on the primer layer. It is preferable that the hard coat layer is made of a silicone resin. The silicone resin is a silicon compound having a polysiloxane bond, and examples thereof include a hard coat layer containing an inorganic silane compound and / or a polyorganosiloxane compound as a main component.

This inorganic silane compound, polyorganosiloxane compound, or a mixture thereof can be produced by various methods as described below. For example, the following general formula [3]
R ¹ _n Si (OR ² ) _4-n [3]
[However, R ¹ in the above general formula is a non-hydrolyzable group, and is an alkyl group, a substituted alkyl group (substituent: halogen atom, epoxy group, (meth) acryloyloxy group etc.), alkenyl group, aryl group. Or an aralkyl group, R < ² > is a lower alkyl group, n is an integer of 0 or 1-3. When there are a plurality of R ¹ and OR ² , the plurality of R ¹ may be the same or different, and the plurality of OR ² may be the same or different.] Hydrolysis using a catalyst such as nitric acid or acetic acid, and polycondensation is used. In this case, an inorganic silane-based binder can be obtained by hydrolyzing a compound of n = 0, that is, tetraalkoxysilane, and a polyorganosiloxane-based binder or a mixture of an inorganic silane-based and polyorganosiloxane-based can be partially hydrolyzed. A system binder is obtained. On the other hand, since a compound with n = 1 to 3 has a non-hydrolyzable group, a polyorganosiloxane-based binder can be obtained by partial or complete hydrolysis. In the above case, an appropriate organic solvent may be used for the purpose of controlling the hydrolysis reaction.

  Examples of the alkoxysilane compound represented by the general formula [3] include tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetraisopropoxysilane, tetra-n-butoxysilane, tetraisobutoxysilane, Tetra-sec-butoxysilane, tetra-tert-butoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, Butyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-acryloyloxypropyltrimethoxysilane, γ-methacryloyl Trimethoxysilane, dimethyl dimethoxysilane, methylphenyl dimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, divinyl dimethoxysilane, divinyl diethoxy silane, trivinyl silane, trivinyl silane, and the like. These may be used alone or in combination of two or more.

  In the hard coat layer, since hard coat performance is regarded as important, a layer containing as much inorganic silane compound as possible is preferable as long as necessary adhesion is maintained. In addition, the hard coat layer may contain an organic ultraviolet absorber, a hindered amine light stabilizer, and the like similar to those of the primer layer as desired, as long as the scratch resistance is not impaired.

  This hard coat layer is obtained by applying a hard coat agent-containing coating solution to the primer layer using a known method such as a bar coat method, a knife coat method, a roll coat method, a blade coat method, a die coat method, or a gravure coat method. It can be formed by coating on and air-drying in the air or curing by heating at room temperature to 150 ° C. for 10 minutes to 2 hours.

  The thickness of the hard coat layer thus formed is preferably in the range of 1 to 20 μm, particularly preferably in the range of 1 to 10 μm, more preferably 2 from the viewpoints of uniform coatability and adhesion, film strength and the like. A range of ˜5 μm is more preferable.

(6) Transparent plastic substrate and highly durable UV-cut plastic substrate The transparent plastic substrate according to the present invention is not particularly limited, but it is a transparent organic resin molded product according to the present invention. This is preferable from the viewpoint of obtaining a highly durable UV-cut plastic substrate.

  And the base resin of a transparent plastic base material is not specifically limited, According to a use, it can select suitably. Specifically, polymethyl methacrylate resin, polycarbonate resin, polystyrene resin, polyester resin, polyacetal resin, polysulfone resin, polyether sulfone resin, polyvinyl chloride resin, polyvinylidene chloride resin, epoxy resin, unsaturated polyester resin, polyurethane Resin, diallyl phthalate resin, diethylene glycol bisallyl carbonate resin, acetyl cellulose resin, sulfur-containing urethane resin or cross-linked (meth) acrylic resin, etc. are mentioned, but polycarbonate resin is particularly preferred because of its excellent strength, heat insulation, and durability. Preferably there is.

  The highly durable UV-cut plastic substrate according to the present invention includes a transparent plastic substrate, a primer layer formed on the transparent plastic substrate, and a hard coat formed on the primer layer as described above. Each layer and base material, such as yellowing and peeling, because it has excellent transparency and ultraviolet absorption (shielding) ability, and the lifetime of ultraviolet absorption (shielding) ability contained in the primer layer is semi-permanent. Can be used for a long period of time.

Next, examples of the present invention will be described in detail with reference to comparative examples. In addition, this invention is not limited to a following example.
[Example 1]
ZnO fine particles (specific surface area 75 m ² / g) 25 parts by weight, methyl isobutyl ketone 62.5 parts by weight, and silicone resin (“220FLAKE” manufactured by Toray Dow Corning Co., Ltd.) at a ratio of 12.5 parts by weight A dispersion in which ZnO fine particles having an average dispersed particle size of 100 nm are dispersed without removing the solvent (methyl isobutyl ketone), while performing dispersion treatment and coating treatment with a silicone resin using a medium stirring mill, That is, a primer layer forming coating solution precursor (solution A) in which ZnO fine particles were coated with a silicone resin was prepared.

  On the other hand, 90 parts by weight of “Primer PH91” manufactured by Momentive Performance Materials Japan G.K. containing acrylic resin binder is added to a benzotriazole ultraviolet absorber (“TINUVIN384-2” manufactured by Ciba Specialty Chemicals Co., Ltd.) 5 5 parts by weight and 5 parts by weight of a hindered amine light stabilizer (“TINUVIN152” manufactured by Ciba Specialty Chemicals Co., Ltd.) were added to prepare a primer solution (solution B) to be mixed with the primer layer forming coating solution precursor. .

  Then, 30 parts by weight of the obtained liquid A (primer layer forming coating liquid precursor) and 70 parts by weight of liquid B (primer liquid) were sufficiently mixed, and the primer layer forming coating liquid according to Example 1 was mixed. Was prepared.

  Next, this primer layer forming coating solution was flow-coated on a polycarbonate plate (“Lexan” manufactured by SABIC) containing an organic ultraviolet absorber and dried at 120 ° C. for 1 hour to form a primer layer. Furthermore, on this primer layer, a polyalkylsiloxane-based hard coat solution (“Tosguard 510” manufactured by Momentive Performance Materials Japan GK) is flow coated and dried at 120 ° C. for 1 hour for the desired hard coat. A layer was formed to produce a highly durable UV-cut plastic substrate according to Example 1.

  And the measurement based on JISK7105 was performed about the total light transmittance and haze value of the film | membrane in the primer layer of the obtained highly durable UV cut plastic base material, and a hard-coat layer.

Furthermore, the durability of the film in the primer layer and the hard coat layer of the obtained highly durable UV cut plastic substrate was evaluated. In addition, this durability evaluation was performed by irradiating ultraviolet rays at 100 mW / cm ² for 500 hours using an ultraviolet irradiation device [“SUV-W131” manufactured by Iwasaki Electric Co., Ltd.]. And it measured by the method similar to the above about the optical characteristic (total light transmittance and haze value) of the film | membrane in the said primer layer and hard-coat layer after ultraviolet irradiation.

The results are shown in Table 1. Table 1 also shows the results obtained in Examples 2 to 4 and Comparative Examples 1 to 3.
[Example 2]
Momentive Performance Materials Japan G.K. which contains 30 parts by weight of the liquid A (a coating liquid precursor for forming a primer layer in which ZnO fine particles are coated with a silicone resin) prepared in Example 1 and an acrylic resin binder “Primer PH91” (ie, primer solution) manufactured by the method was sufficiently mixed at a ratio of 70 parts by weight to prepare a primer layer forming coating solution according to Example 2.

  Next, this primer layer forming coating solution was flow-coated on a polycarbonate plate (“Lexan” manufactured by SABIC) containing an organic ultraviolet absorber and dried at 120 ° C. for 1 hour to form a primer layer. Furthermore, on this primer layer, a polyalkylsiloxane-based hard coat solution (“Tosguard 510” manufactured by Momentive Performance Materials Japan GK) is flow coated and dried at 120 ° C. for 1 hour for the desired hard coat. A layer was formed to produce a highly durable UV cut plastic substrate according to Example 2.

  And about the obtained highly durable UV cut plastic base material, the optical characteristic (total light transmittance and haze value) and durability evaluation of the film | membrane were performed by the method similar to Example 1. FIG.

The results are also shown in Table 1.
[Example 3]
25 parts by weight of ZnO fine particles (specific surface area 75 m ² / g), 72.5 parts by weight of methyl isobutyl ketone, and 2.5 parts by weight of silicone resin (“220FLAKE” manufactured by Toray Dow Corning Co., Ltd.) A dispersion in which ZnO fine particles having an average dispersed particle size of 100 nm are dispersed without removing the solvent (methyl isobutyl ketone), while performing dispersion treatment and coating treatment with a silicone resin using a medium stirring mill, That is, a primer layer forming coating solution precursor (solution C) in which ZnO fine particles were coated with a silicone resin was prepared.

  Then, 30 parts by weight of the obtained liquid C (primer layer forming coating liquid precursor in which ZnO fine particles are coated with a silicone resin), liquid B (primer) containing the acrylic resin binder prepared in Example 1 Liquid) was sufficiently mixed at a ratio of 70 parts by weight to prepare a primer layer forming coating solution according to Example 3.

  Next, this primer layer forming coating solution was flow-coated on a polycarbonate plate (“Lexan” manufactured by SABIC) containing an organic ultraviolet absorber and dried at 120 ° C. for 1 hour to form a primer layer. Furthermore, on this primer layer, a polyalkylsiloxane-based hard coat solution (“Tosguard 510” manufactured by Momentive Performance Materials Japan GK) is flow coated and dried at 120 ° C. for 1 hour for the desired hard coat. A layer was formed to produce a highly durable UV cut plastic substrate according to Example 3.

  And about the obtained highly durable UV cut plastic base material, the optical characteristic (total light transmittance and haze value) and durability evaluation of the film | membrane were performed by the method similar to Example 1. FIG.

The results are also shown in Table 1.
[Example 4]
25 parts by weight of ZnO fine particles (specific surface area 75 m ² / g), 25 parts by weight of methyl isobutyl ketone, and 50 parts by weight of silicone resin (“220FLAKE” manufactured by Toray Dow Corning Co., Ltd.) A dispersion in which ZnO fine particles having an average dispersed particle diameter of 100 nm are dispersed without removing the solvent (methyl isobutyl ketone), ie, dispersion treatment and silicone resin coating treatment using a medium stirring mill, ie, ZnO fine particles A primer layer forming coating solution precursor (solution D) coated with a silicone resin was prepared.

  And 30 parts by weight of the obtained D liquid (primer layer forming coating liquid precursor in which ZnO fine particles are coated with a silicone resin), B liquid (primer) containing the acrylic resin binder prepared in Example 1 Liquid) was sufficiently mixed at a ratio of 70 parts by weight to prepare a primer layer forming coating solution according to Example 4.

  Next, this primer layer forming coating solution was flow-coated on a polycarbonate plate (“Lexan” manufactured by SABIC) containing an organic ultraviolet absorber and dried at 120 ° C. for 1 hour to form a primer layer. Furthermore, on this primer layer, a polyalkylsiloxane-based hard coat solution (“Tosguard 510” manufactured by Momentive Performance Materials Japan GK) is flow coated and dried at 120 ° C. for 1 hour for the desired hard coat. A layer was formed to produce a highly durable UV-cut plastic substrate according to Example 4.

  And about the obtained highly durable UV cut plastic base material, the optical characteristic (total light transmittance and haze value) and durability evaluation of the film | membrane were performed by the method similar to Example 1. FIG.

The results are also shown in Table 1.
[Comparative Example 1]
Momentive Performance Materials Japan GK “Primer PH91” (that is, primer solution) containing an acrylic resin binder flows onto a polycarbonate plate with organic UV absorber (SABIC “Lexan”). Coat and dry at 120 ° C. for 1 hour to form a primer layer. Furthermore, on this primer layer, a polyalkylsiloxane-based hard coat solution (“Tosguard 510” manufactured by Momentive Performance Materials Japan GK) is flow coated and dried at 120 ° C. for 1 hour for the desired hard coat. A layer was formed to produce a durable UV-cut plastic substrate according to Comparative Example 1.

  And about the obtained durable UV cut plastic base material, the optical characteristic (total light transmittance and haze value) and durability evaluation of the film | membrane were performed by the method similar to Example 1. FIG.

The results are also shown in Table 1.
[Comparative Example 2]
The B liquid (primer liquid) containing the acrylic resin binder prepared in Example 1 is flow-coated on a polycarbonate plate (“Lexan” manufactured by SABIC) containing an organic ultraviolet absorber, and then at 120 ° C. for 1 hour. The primer layer was formed by drying. Furthermore, on this primer layer, a polyalkylsiloxane-based hard coat solution (“Tosguard 510” manufactured by Momentive Performance Materials Japan GK) is flow coated and dried at 120 ° C. for 1 hour for the desired hard coat. A layer was formed to produce a durable UV-cut plastic substrate according to Comparative Example 2.

  And about the obtained durable UV cut plastic base material, the optical characteristic (total light transmittance and haze value) and durability evaluation of the film | membrane were performed by the method similar to Example 1. FIG.

The results are also shown in Table 1.
[Comparative Example 3]
25 parts by weight of ZnO fine particles (specific surface area 75 m ² / g), 62.5 parts by weight of methyl isobutyl ketone, and 12.5 parts by weight of a dispersant for dispersing fine particles were mixed, and a medium stirring mill was used. A dispersion in which ZnO fine particles having an average dispersed particle size of 100 nm are dispersed without removing the solvent (methyl isobutyl ketone), that is, forming a primer layer in which the ZnO fine particles are not coated with a silicone resin. A coating solution precursor (E solution) was prepared.

  And 30 parts by weight of the obtained E solution (primer layer forming coating solution precursor in which ZnO fine particles are not coated with silicone resin), B solution containing the acrylic resin binder prepared in Example 1 ( Primer solution) was sufficiently mixed at a ratio of 70 parts by weight to prepare a primer layer forming coating solution according to Comparative Example 3.

  Next, this primer layer forming coating solution was flow-coated on a polycarbonate plate (“Lexan” manufactured by SABIC) containing an organic ultraviolet absorber and dried at 120 ° C. for 1 hour to form a primer layer. Furthermore, on this primer layer, a polyalkylsiloxane-based hard coat solution (“Tosguard 510” manufactured by Momentive Performance Materials Japan GK) is flow coated and dried at 120 ° C. for 1 hour for the desired hard coat. A layer was formed to produce a durable UV-cut plastic substrate according to Comparative Example 3.

  And about the obtained durable UV cut plastic base material, the optical characteristic (total light transmittance and haze value) and durability evaluation of the film | membrane were performed by the method similar to Example 1. FIG.

  The results are also shown in Table 1.

"Evaluation"
(1) About the durable UV cut plastic base material which concerns on the comparative example 1 manufactured by applying the primer liquid (primer PH91) which does not contain an ultraviolet absorber, the haze value and total light transmittance in 500 hours of ultraviolet irradiation From the results of Table 1 showing the change of the haze value, the change width of the haze value is 19.8% (20.0-0.2%), and the change width of the total light transmittance is 20.5% (91.5-71. 0%) and the ultraviolet durability is extremely inferior, and it is confirmed that the film appearance change (yellowing, cloudiness, cracks) is also remarkable.

(2) Further, regarding a durable UV-cut plastic substrate according to Comparative Example 2 manufactured by applying a primer solution (primer PH91) containing a benzotriazole ultraviolet absorber and a hindered amine light stabilizer, From the result of 1, the change width of the haze value is 9.8% (10.0-0.2%) and the change width of the total light transmittance is 12% (92.0-80.0%). Although UV durability is slightly better than Example 1, it is confirmed that changes in film appearance (yellowing, cloudiness, cracks) are not different from Comparative Example 1.

(3) In addition, a primer layer forming coating solution precursor in which ZnO fine particles are not coated with a silicone resin, and a primer solution (primer PH91) containing a benzotriazole ultraviolet absorber and a hindered amine light stabilizer From the results shown in Table 1, the change in haze value was 15.1% for the durable UV-cut plastic substrate according to Comparative Example 3 manufactured by applying the primer layer forming coating solution prepared by mixing (15.5-0.4%), the change width of the total light transmittance is 5.5% (88.0-82.5%), and the ultraviolet durability is superior to Comparative Example 1 and Comparative Example 2. In addition, it is confirmed that the film appearance change (white turbidity) is superior to that of Comparative Example 1 and Comparative Example 2. However, it is also confirmed that the change range of the haze value is large.

(4) Compared with these comparative examples, the highly durable UV-cut plastic substrate according to Examples 1 to 4 has almost no change in appearance (crack, choking, bleed), haze value and total light transmittance. The change widths are 0.1% or less and 0.3% or less, respectively, and it is confirmed that the ultraviolet durability is greatly improved.

  According to the present invention, unlike the conventional wet surface treatment method on the surface of zinc oxide fine particles, the primer layer forming application to which the inorganic ultraviolet absorber is applied without the need for solvent removal / drying step, redispersion step, etc. In the paint and plastics industry, where market prices have been established with inexpensive organic UV absorbers, it can be used as an inexpensive primer layer forming coating solution that uses inorganic UV absorbers. Has the above applicability.

Claims (12)

Primer for forming the above-mentioned primer layer of a highly durable UV-cut plastic substrate having a transparent plastic substrate, a primer layer formed on the transparent plastic substrate, and a hard coat layer formed on the primer layer In the coating liquid for layer formation,
A silane compound is charged into a mill base composed of zinc oxide raw material powder and a solvent, and the zinc oxide raw material powder is pulverized and the surface of the pulverized zinc oxide fine particles is coated with the silane compound using a wet medium stirring mill. A primer layer-forming coating solution precursor containing a coating-treated zinc oxide fine particle having a primary particle diameter of 100 nm or less and a solvent prepared without removal, and an acrylic system mixed with the primer layer-forming coating solution precursor A polysiloxane comprising a resin binder and consisting of repeating siloxane bonds (Si-O-Si) as a main chain (however, each silicon atom constituting the main chain is composed of four oxygen atoms, the Q unit structure coupled to the conditions), and one or more molecular end alkoxysilyl group (Si-oR) and / or silanol groups (Si- H) blocked with a silicone resin having a hydrocarbon group having 1 to 18 carbon atoms and / or a phenyl group in the molecule as an organic substituent, and forming the primer layer Coating liquid.   2. The primer layer forming coating solution according to claim 1, wherein the silicone resin is contained in an amount of 10 to 300 parts by weight per 100 parts by weight of the zinc oxide fine particles.   The primer layer-forming coating solution according to claim 1, wherein the acrylic resin binder is a (meth) acrylic resin obtained by polymerizing an alkyl acrylate monomer or an alkyl methacrylate monomer.   The coating liquid for forming a primer layer according to any one of claims 1 to 3, wherein the zinc oxide fine particles are contained in an amount of 30 to 500 parts by weight with respect to 100 parts by weight of the acrylic resin binder.   5. The primer layer-forming coating according to claim 1, comprising at least one organic ultraviolet absorber selected from benzophenone derivatives, benzotriazole derivatives, triazine derivatives, and cyanoacrylate derivatives. liquid.   It contains one or more hindered amine light stabilizers selected from 2,2,6,6-tetramethylpiperidine derivatives and 1,2,2,6,6-pentamethyl-4-piperidine derivatives. The coating liquid for primer layer formation in any one of Claims 1-5.   A primer layer obtained by heat-curing a coating layer formed by coating the primer layer-forming coating solution according to claim 1 on a transparent plastic substrate.   The primer layer according to claim 7, wherein the primer layer has a haze value of 1.5% or less when the ultraviolet transmittance is 10% or less.   A transparent plastic substrate, a primer layer having a film thickness of 1 to 20 μm formed on the transparent plastic substrate using the primer layer forming coating solution according to claim 1, and a primer layer A highly durable UV cut plastic substrate comprising a hard cord layer having a thickness of 1 to 20 μm.   The long-lasting UV-cut plastic substrate according to claim 9, wherein the hard coat layer is a silicone-based resin.   The transparent plastic base material is polymethyl methacrylate resin, polycarbonate resin, polystyrene resin, polyester resin, polyacetal resin, polysulfone resin, polyether sulfone resin, polyvinyl chloride resin, polyvinylidene chloride resin, epoxy resin, unsaturated polyester resin. The high durability UV according to claim 9, which is any one of a polyurethane resin, a diallyl phthalate resin, a diethylene glycol bisallyl carbonate resin, an acetyl cellulose resin, a sulfur-containing urethane resin, or a crosslinked (meth) acrylic resin. Cut plastic substrate.   The highly durable UV-cut plastic substrate according to claim 9, wherein the transparent plastic substrate is a polycarbonate resin.