JP2023158011A - Method for manufacturing organic glass molding having hard coat layer - Google Patents

Abstract

To provide an organic glass molding having a hard coat layer, capable of maintaining high transparency even after being bent by heating at high temperature.SOLUTION: The method for manufacturing an organic glass molding having a hard coat layer comprises: the heating step of heating organic glass having a hard coat layer and obtained by thermally transferring the hard coat layer on an organic glass base; and the bending step of bending the organic glass having the hard coat layer after the heating. The heating step includes heating the organic glass having the hard coat layer by radiant heat until the surface temperature of the organic glass having the hard coat layer reaches a predetermined bending preparation temperature.SELECTED DRAWING: Figure 3

Description

The present invention relates to a method for producing an organic glass molded product with a hard coat layer. More specifically, the present invention relates to a manufacturing method capable of obtaining an organic glass molded product with a hard coat layer that maintains high transparency even after bending work that involves heating at high temperatures.

In order to impart scratch resistance to the surface of organic glass, a hard coat layer is formed on the surface. In addition to scratch resistance, in particular, when the organic glass mentioned above is a highly transparent base material such as a polycarbonate plate, in order to take advantage of the high transparency of the base material itself, transparent organic glass molded products with a hard coat layer are also required. sexuality is required.

For example, Patent Document 1 listed below discloses a structure in which a primer layer and a hard coat layer are laminated on a polycarbonate plate by extruding the polycarbonate plate and transferring it using a thermal transfer film. There is.

When such an organic glass with a hard coat layer is bent after being heated at a high temperature, there has been a problem in that the imaging ratio of the molded product after the bending process is reduced.

Japanese Patent Application Publication No. 2005-178035

An object of the present invention is to provide an organic glass molded product with a hard coat layer that maintains high transparency even after bending work that involves heating at high temperatures.

As a result of intensive studies to solve the above problems, the present inventors discovered that the above problems could be solved by limiting the heating method performed before bending to heating using radiant heat, and completed the present invention. I ended up doing it.

(1) The method includes a heating step of heating an organic glass with a hard coat layer formed by thermally transferring a hard coat layer onto an organic glass substrate, and a bending step of bending the heated organic glass with a hard coat layer. . A method for manufacturing an organic glass molded product with a hard coat layer, wherein in the heating step, heating is performed using radiant heat until the surface temperature of the organic glass with the hard coat layer reaches a predetermined bending preparation temperature.

(2) In the heating step, the heating time until the surface temperature of the organic glass with the hard coat layer reaches the bending preparation temperature is shorter than the limit heating time corresponding to the bending preparation temperature specified below. The method for producing an organic glass molded product with a hard coat layer according to (1), wherein the time is set as the time.
(Limit heating time)
After heating the organic glass with a hard coat layer until the surface temperature reaches a preset bending preparation temperature, the mapping ratio of the organic glass with a hard coat layer determined by the following mapping ratio measurement method becomes the predetermined lower limit mapping ratio. The heating time is defined as the limit heating time corresponding to the bending preparation temperature of the organic glass with the hard coat layer.
(Method for measuring imaging ratio)
Using a mapping ratio measuring device compliant with JIS K7374:2007, the hard coat layer of organic glass with a hard coat layer is placed on a sample stand with the hard coat layer facing the light source, and measurement is performed at a reflection angle of 60° and a comb width of 2 mm.

(3) The method for producing an organic glass molded product with a hard coat layer according to (2), wherein the lower limit mapping ratio is 90%.

(4) The bending preparation temperature is 120° C. or more and 140° C. or less, and the heating time until the surface temperature of the hard coat layer-equipped organic glass reaches the bending preparation temperature is 150 seconds or less, (1) The method for producing an organic glass molded product with a hard coat layer according to any one of (3) above.

(5) The bending preparation temperature is 150°C or more and 160°C or less, and the heating time until the surface temperature of the hard coat layer-equipped organic glass reaches the bending preparation temperature is 200 seconds or less, (1) The method for producing an organic glass molded product with a hard coat layer according to any one of (3) above.
(6) The method for producing an organic glass molded product with a hard coat layer according to any one of (1) to (5), wherein the radiant heat is radiant heat from infrared rays.

(7) The method for manufacturing an organic glass molded product with a hard coat layer according to (6), wherein the infrared ray is a mid-infrared ray having a center wavelength of 2.5 μm or more and 5.0 μm or less.

It is possible to provide an organic glass molded product with a hard coat layer that maintains high transparency even after bending that involves heating at high temperatures.

1 is a schematic diagram showing an example of a method for producing an organic glass molded product with a hard coat layer according to the present invention. FIG. 1 is a schematic cross-sectional view showing the layer structure of an organic glass with a hard coat layer constituting the molded organic glass with a hard coat layer of the present invention. FIG. 1 is a schematic cross-sectional view showing the layer structure of an organic glass molded product with a hard coat layer that can be obtained by the manufacturing method of the present invention.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the purpose of the present invention. can.

<Organic glass molded product with hard coat layer>
The organic glass molded product 100 with a hard coat layer (see FIG. 3) of the present invention has a hard coat layer 12b formed on the surface of the organic glass substrate 11 (see FIG. 2). It is a processed molded product.

In addition, the mapping rate of the organic glass molded product 100 with a hard coat layer (see Figure 3) may be as long as it satisfies each requirement in accordance with the level of transparency required for each product, but usually Preferably, the ratio is greater than 90%. By the "method for producing an organic glass molded product with a hard coat layer" of the present invention, it is possible to obtain the organic glass molded product 100 with a hard coat layer that has excellent transparency.

In this specification, the term "mapping ratio" refers to a measured value that can be obtained by the "mapping ratio measuring method" described below, unless otherwise specified.
(Method for measuring imaging ratio)
Using a mapping ratio measuring device compliant with JIS K7374:2007, the hard coat layer of organic glass with a hard coat layer was placed on a sample stand with the hard coat layer facing the light source, and the measurement was performed at a reflection angle of 60° and a comb width of 2 mm.

<Organic glass with hard coat layer>
The details of the organic glass 10 with a hard coat layer used in the "method for producing an organic glass molded product with a hard coat layer" of the present invention will be explained. The organic glass 10 with a hard coat layer is a laminate in which a hard coat layer 12b is thermally transferred to at least one surface of the organic glass substrate 11. The organic glass 10 with a hard coat layer can be manufactured by a method of thermally transferring a "transfer sheet 12 with a hard coat layer" described below onto the surface of the organic glass substrate 11.

By subjecting this organic glass 10 with a hard coat layer to the "heating step" and "bending step" that constitute the "method for manufacturing an organic glass molded product with a hard coat layer" of the present invention, the transparency after bending is improved. An excellent organic glass molded product 100 with a hard coat layer can be obtained.

[Basic configuration]
In the hard coat layer-equipped organic glass 10, the hard coat layer 12b is usually bonded to the organic glass substrate 11 via two adhesive layers (see FIG. 2). The two adhesive layers are a heat seal layer 12d formed on the surface of the organic glass substrate 11, and a primer layer 12c formed between the heat seal layer 12d and the hard coat layer 12b. Note that the term "adhesive layer" in this specification includes the above-mentioned heat seal layer and primer layer, and any of these layers is also included in the "adhesive layer" in this specification.

In the hard coat layer-equipped organic glass 10 having the above-described layer structure, the primer layer 12c usually contains a particulate antiblocking agent. In the primer layer 12c, the particle size (secondary particle size after aggregation) of the particulate antiblocking agent contained in the same layer is larger than the thickness of the primer layer 12c itself, at least in part thereof. Due to the existence of the portion where the hard coat layer is attached, blocking of the primer layer 12c during the manufacturing process of the hard coat layer-equipped organic glass 10 can be sufficiently avoided.

When the secondary particle size of at least some of the inorganic fillers contained as an anti-blocking agent in the primer layer 12c of the hard coat layer-equipped organic glass 10 exceeds the thickness of the primer layer 12c, These particles (antiblocking agent) tend to be a cause of a decrease in image clarity. Therefore, in such a case, the method for manufacturing an organic glass molded product with a hard coat layer according to the present invention is particularly superior to conventional manufacturing methods.

[Organic glass substrate]
Regarding the organic glass substrate 11 constituting the organic glass with hard coat layer 10, various organic glasses can be appropriately selected depending on the desired molded product. However, as described above, the hard coat layer-equipped organic glass 10 is characterized by a small decrease in image mapping after bending processing that involves heating at high temperatures. From the viewpoint of taking advantage of this excellent feature, it is preferable to use an organic glass plate having excellent transparency as the organic glass substrate 11. Specifically, an organic glass plate made of polycarbonate resin, ABS resin, acrylic resin, or the like can be cited as a specific example of a preferable organic glass plate.

The thickness of the organic glass substrate 11 plate made of polycarbonate resin or the like is not particularly limited. However, this thickness is preferably 1 mm or more and 20 mm or less, and more preferably 1.5 mm or more and 15 mm or less.

(Hard coat layer)
The hard coat layer 12b is a layer that has a function of imparting scratch resistance to the surfaces of the hard coat layer-equipped organic glass 10 and the hard coat layer-equipped organic glass molded product 100.

The hard coat layer 12b is a layer made of a cured product of a curable resin composition. The main resin of the curable resin composition forming the hard coat layer 12b is not particularly limited. However, for example, polyester resin, epoxy resin, polyurethane resin, amino alkyd resin, melamine resin, guanamine resin, urea resin, thermosetting acrylic resin, ionizing radiation curable resin, etc. are preferred resins for forming the hard coat layer 12b. This can be mentioned as a specific example. From the viewpoint of imparting higher levels of weather resistance and scratch resistance, among the above, it is preferable that the resin forming the hard coat layer 12b be an ionizing radiation curable resin.

The ionizing radiation curable resin is a curable resin that is cured by irradiation with ionizing radiation, and examples of ionizing radiation include electromagnetic waves or charged particle beams that have energy quantum capable of polymerizing or crosslinking molecules, such as: In addition to ultraviolet light (UV) or electron beams (EB), electromagnetic waves such as X-rays and γ-rays, and charged particle beams such as α-rays and ion beams are also used.

The ionizing radiation-curable resin that can be used for the hard coat layer 12b can be appropriately selected from polymerizable oligomers (prepolymers) and polymerizable polymers that have been conventionally used as resins that have ionizing radiation-curable properties. In order to obtain good curing characteristics, it is difficult to bleed out, has coating properties even when the solid content is about 95 to 100%, and has no curing shrinkage when curing to form the hard coat layer 12b. Preferably, those that do not occur easily.

The thickness of the hard coat layer 12b is not particularly limited. However, the thickness is usually about 1 μm or more and 20 μm or less. The thickness of the hard coat layer 12b is preferably 2 μm or more and 20 μm or less, and 2 μm or more, from the viewpoint of obtaining excellent weather resistance and its sustainability, and from the viewpoint of maintaining the transparency of the hard coat layer-equipped organic glass 10. More preferably, it is 10 μm or less.

The uncured resin layer formed by applying the resin composition described above becomes the hard coat layer 12b by being cured by heat treatment or by irradiation with ionizing radiation such as an electron beam. When using an electron beam as the ionizing radiation, the accelerating voltage can be selected appropriately depending on the resin used and the thickness of the layer, but usually the accelerating voltage is 70 kV or more and 300 kV or less, and the irradiation dose is about 5 Mrad or more and 10 Mrad or less. It is preferable to cure the uncured resin layer.

(Primer layer)
The primer layer 12c is arranged between the hard coat layer 12b and the heat seal layer 12d in the organic glass 10 with a hard coat layer, and is arranged between the hard coat layer 12b and the heat seal layer 12d in the organic glass 10 with a hard coat layer and the organic glass molded product 100 with a hard coat layer. This layer functions as a stress relaxation layer for the hard coat layer 12b and also has a function of improving the adhesion of the hard coat layer 12b to the organic glass substrate 11.

The primer layer of the transfer sheet 12 with a hard coat layer, that is, the primer layer 12c of the organic glass 10 with a hard coat layer, is formed using a composition for forming a primer layer containing a binder resin. The binder resin contained in the composition for forming a primer layer is not particularly limited, but preferably contains a two-part curable resin consisting of a main resin and a curing agent.

As the above-mentioned main material used to form the primer layer 12c, for example, polyurethane resin, (meth)acrylic resin, vinyl chloride/vinyl acetate copolymer, polyester resin, petitral resin, chlorinated polypropylene, chlorinated polyethylene, etc. can be used. I can do it. These binder resins may be used alone or in combination of two or more. Among these binder resins, polyurethane resins are preferably used from the viewpoint of adhesiveness and weather resistance.

Examples of the curing agent that accelerates the curing of each of the above main ingredients used in forming the primer layer 12c include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, cyclohexanephenylene diisocyanate, naphthalene-1,5-diisocyanate, and the like. Isocyanate curing agents and the like can be used.

The thickness of the primer layer 12c is not particularly limited, but is preferably, for example, 0.1 μm or more and 5 μm or less, more preferably 1 μm or more and 4 μm or less.

The primer layer 12c having such a thickness contains a particulate antiblocking agent. This antiblocking agent can be appropriately selected from known antiblocking agents made of inorganic particles and the like that have been conventionally used in various resin laminate molded products.

As described above, the particle size of at least some of the particles of the inorganic filler, which is an anti-blocking agent, contained in the primer layer 12c of the organic glass 10 with a hard coat layer depends on the thickness of the primer layer. The present invention is particularly effective when the Here, the above-mentioned "particle size of the antiblocking agent (particles)" refers to the particle size of the secondary particles after the aggregation when the primary particles are aggregated within the primer layer 12c.

Inorganic particles such as silica, alumina, aluminum hydroxide, barium sulfate, talc, and calcium carbonate can be preferably used as particulate antiblocking agents to be included in the primer layer 12c of organic glass with a hard coat layer. This can be mentioned as a specific example. These inorganic particles can not only sufficiently suppress the occurrence of blocking phenomena during the manufacturing stage, but also have high transparency, so they can be used to form organic glass with hard coat layer 10 and organic glass with hard coat layer 10. It is easy to maintain a high level of transparency.

From the viewpoint of suppressing blocking while maintaining transparency, the average particle size of the antiblocking agent is preferably about 0.1 to 10 μm. It is preferable that at least a part of the particles, preferably more than half of all the particles, actually exceed the thickness of the primer layer described above (preferably 0.1 μm or more and 5 μm or less). Incidentally, the particle size of the antiblocking agent can be measured using a laser diffraction type particle size distribution analyzer.

Further, the content of the antiblocking agent is preferably 0.1 parts by mass or more and 30 parts by mass or less, more preferably 3 parts by mass or more and 20 parts by mass or less, based on 100 parts by mass of the above binder resin. preferable.

In addition, the primer layer 12c may contain various additives other than those mentioned above, as necessary, within a range that does not impair the effects of the present invention. Examples of such additives include ultraviolet absorbers, light stabilizers, wear resistance improvers, infrared absorbers, antistatic agents, adhesion improvers, leveling agents, thixotropic agents, coupling agents, and plasticizers. agent, antifoaming agent, filler, solvent, coloring agent, etc. These additives can be appropriately selected from commonly used additives.

(heat seal layer)
The heat seal layer 12d is a layer provided to bond the hard coat layer 12b to the organic glass substrate 11 in order to form the hard coat layer 12b on the surface of the transfer body. It has a function of adhering to the base 11.

Resins with thermal fusibility that can be used for the heat-sealing layer 12d are determined depending on the material of the organic glass substrate 11 and the transfer temperature and pressure during thermal transfer, but generally acrylic resins, Resins such as vinyl chloride-vinyl acetate copolymer, polyamide resin, polyester resin, chlorinated polypropylene, chlorinated rubber, urethane resin, epoxy resin, and styrene resin are preferable, depending on the material of the organic glass substrate 11 and the use of the transfer product. One or more resins are selected from among the above resins. Among the above-mentioned resins, it is particularly preferable to use an acrylic resin alone, since it has a small refractive index difference with the particles contained in the primer layer 12c and has excellent transparency, and improves transparency and weather resistance.

Like the hard coat layer 12b and primer layer 12c, the heat seal layer 12d can also contain a weather resistance improving agent such as an ultraviolet absorber or a light stabilizer in order to further improve weather resistance. As the ultraviolet absorber and light stabilizer that can be used, various resins and additives similar to those described in the primer layer 12c can be used as appropriate.

The thickness of the heat seal layer 12d is preferably 1 μm or more and 7 μm or less, and 1 μm or more and 6 μm or less, from the viewpoint of adhering the hard coat layer 12b to the organic glass substrate 11 and ensuring excellent transparency. It is more preferable that it is below.

[Transfer sheet with hard coat layer]
In order to obtain the organic glass 10 with a hard coat layer by integrating the laminate including the hard coat layer 12b, primer layer 12c, and heat seal layer 12d described above on the surface of the organic glass substrate 11, It is preferable to use the transfer sheet 12 with a coat layer.

The transfer sheet 12 with a hard coat layer includes, for example, each resin that will constitute the hard coat layer 12b, the primer layer 12c, and the heat seal layer 12d of the organic glass 10 with a hard coat layer on a base film such as a polyester film. It is a material laminate in which the layers are stacked in this order.

When producing organic glass 10 with a hard coat layer using the transfer sheet 12 with a hard coat layer, the transfer sheet 12 with a hard coat layer is laminated with the heat seal layer 12d facing the surface of the organic glass substrate 11. The hard coat layer-equipped transfer sheet 12 is transferred onto the surface of the organic glass substrate 11 by heat-pressing. Through this transfer process, a heat seal layer 12d, a primer layer 12c, and a hard coat layer 12b are laminated in this order on the surface of the organic glass substrate 11 (see FIG. 2). can be obtained.

The material of the base film constituting the hard coat layer-equipped transfer sheet 12 is not particularly limited. However, the material of the base film is preferably a polyester resin film or a polyolefin resin film. Moreover, among the above films, a stretched film is more preferable. When the base film is one of these resin films, the hard coat layer can be easily formed. Note that this base film is not an essential component of the hard coat layer-equipped organic glass 10, and is usually peeled off after the above thermal transfer is completed.

Examples of polyester resin films that can be preferably used as the above-mentioned base film include polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, polyarylate, polycarbonate, and ethylene terephthalate-isophthalate copolymer. Various resin films can be mentioned.

<Production method of organic glass molded product with hard coat layer>
Hereinafter, a manufacturing method for manufacturing the organic glass molded product 100 with a hard coat layer will be described. In the following, (a) a step of obtaining an organic glass substrate by extrusion molding, (b) a step of heating the organic glass substrate, (c) a step of transferring a hard coat layer to the organic glass substrate, (d) a hard coat layer. As a total process in which all steps of heating the organic glass with a hard coat layer (heating step in the manufacturing method of the present invention) and (e) bending the organic glass with a hard coat layer (bending step in the manufacturing method of the present invention) are performed in-line. The implementation will be explained by taking as an example (see FIG. 1).

However, the "method for producing an organic glass molded product with a hard coat layer" of the present invention is not limited to the embodiments described below. At least, an "organic glass molded product with a hard coat layer" is manufactured by a "heating step" of heating organic glass with a hard coat layer formed by thermally transferring a hard coat layer onto an organic glass substrate, followed by a "bending step". If it is a method, it is a process within the technical scope of the present invention, regardless of whether or not other steps (for example, steps (a) to (c) above) are implemented or the implementation mode. For example, the organic glass 10 with a hard coat layer to be introduced into the heating step (d) can be obtained through each of the steps (a) to (c), but is not limited thereto. The manufacturing method of the present invention can also be carried out by acquiring an already finished organic glass with a hard coat layer from the market and introducing it into the heating step (d).

Note that the manufacturing method of the present invention for manufacturing the organic glass molded product 100 with a hard coat layer is not limited to an in-line continuous process as shown in FIG. The manufacturing method may be such that each step is performed independently off-line. Each step will be explained below.

[(a) Step of obtaining organic glass substrate by extrusion molding]
Extrusion molding can be performed by a conventionally known method. For example, the material resin (polycarbonate resin) of the organic glass substrate 11 (polycarbonate plate) is heated and melted, extruded from the die of the extruder 20, rolled with a cooling roll, passed through a guide roll, and cooled while being taken up with a take-up roll. By solidifying, the organic glass substrate 11 (polycarbonate plate) can be obtained.

[(b) Step of heating the organic glass substrate]
Next, the extruded organic glass substrate 11 is heated using heaters 30a and 30b. Although heating is performed from both sides in FIG. 1(b), heating may be performed from one side of the organic glass substrate 11. Note that this step is not necessarily an essential step.

[(c) Step of transferring the hard coat layer onto the organic glass substrate]
In order to transfer the laminate including the hard coat layer 12b, primer layer 12c, and heat seal layer 12d (hereinafter also referred to as "transfer layer") to the organic glass substrate 11, as shown in FIG. The transfer sheet 12 with a hard coat layer was unwound from the winding bodies of paper feed rolls 41a and 41b, and the surface of the organic glass substrate 11 such as a polycarbonate plate was made to face the heat seal layer 12d of the transfer sheet 12 with a hard coat layer. In this state, the base film 12a is bonded by heating and pressurizing with the nip rolls 42a and 42b, and then the base film 12a is peeled off. Thereby, the organic glass 10 with a hard coat layer can be obtained.

Although the base film can be peeled off after the subsequent "bending process," it is preferable to peel it off before the bending process for ease of peeling. The method of peeling the base film 12a from the laminate of the transfer sheet 12 with a hard coat layer and the organic glass substrate 11 is not particularly limited, but for example, the base film is peeled off from the laminate of the transfer sheet 12 with a hard coat layer 12 and the organic glass substrate 11 to the discharge rolls 44a and 44b via the peeling rolls 43a and 43b. By winding up the film 12a, the base film 12a can be continuously peeled off from the laminate.

[(d) Heating process]
This step is a step in which, prior to the subsequent bending step, the hard coat layer-attached organic glass 10, in which the hard coat layer is thermally transferred onto the organic glass substrate obtained in the previous step, is heated. Conventionally, for heating as a preparatory treatment for this bending process, various known heating means have been selected without particular limitation, such as partial heating with a pipe heater, infrared heater, and overall heating with an electric furnace, but the manufacturing method of the present invention In this case, the heating means was limited to heating by radiant heat such as an infrared heater. In other words, the "heating step" constituting the "method for producing an organic glass molded product with a hard coat layer" of the present invention refers to the heating process using radiant heat until the surface temperature of the organic glass with a hard coat layer reaches a predetermined "bending treatment preparation temperature". This is a process of heating.

This "bending treatment preparation temperature" may be any temperature at which the surface temperature of the organic glass substrate 11 constituting the hard coat layer-equipped organic glass 10 is equal to or higher than the glass transition temperature (Tg). For example, if the organic glass substrate 11 is made of polycarbonate In the case of a plate, although it depends on the glass transition temperature (Tg) specific to each polycarbonate plate, the temperature is usually 120°C or higher, and preferably 150°C or higher and 180°C or lower.

In the heating step, it is preferable to heat the organic glass with a hard coat layer until the surface temperature reaches the above-mentioned "bending treatment preparation temperature" within a predetermined short time. Specifically, the heating time until the surface temperature of the organic glass with a hard coat layer reaches the "bending treatment preparation temperature" that is preset for each process is shorter than the "limit heating time" defined below. It is preferable to set the heating conditions so that
(Limit heating time)
After heating the organic glass with a hard coat layer until the surface temperature reaches a preset bending preparation temperature, the mapping ratio of the organic glass with a hard coat layer determined by the following mapping ratio measurement method becomes the predetermined lower limit mapping ratio. The heating time is defined as the limit heating time corresponding to the bending preparation temperature of the organic glass with the hard coat layer.

It is generally known that the image mapping ratio of organic glass with a hard coat layer gradually decreases as the temperature of the organic glass substrate increases. The present inventors conducted further research and found that even when heating to the same temperature, by reaching the required temperature in a shorter time using radiant heat, it is possible to suppress a decrease in the mapping ratio. For example, if the lower limit mapping ratio is specified as 90% due to the transparency required for the product, and the "bending preparation temperature" is 140°C, if the heating time is longer than a certain level, The mapping ratio of the organic glass substrate is less than 90%. By shortening the heating time by setting the heating conditions, the mapping ratio can be maintained at 90% when the temperature reaches 140°C. The heating time at this time is the "limit heating time".

Make the heating time shorter than the "limit heating time" above. In other words, the effect of maintaining transparency by optimizing the heating conditions so that the surface temperature of the organic glass with a hard coat layer reaches the preset "bending treatment preparation temperature" in a shorter time can be improved by using various ovens, etc. Although it is difficult to become obvious due to heat transfer by convection, research by the present inventors has revealed that it is more likely to become obvious by heating by radiant heat such as an infrared heater. Specifically, when the lower limit of the mapping rate is 92%, the mapping rate of organic glass with a hard coat layer decreases to 92% when heated in an oven at a surface temperature of 110°C, but when heated with an infrared heater, the mapping rate decreases to 92%. It has been confirmed that a mapping ratio of 92% or more can be maintained up to 150°C.

Additionally, compared to convection ovens, it is easier to precisely set the time required to raise the temperature of the object to be heated with radiant heat heaters such as infrared heaters. Heating by radiant heat is also effective at this point.

Incidentally, the "mapping rate" related to the above-mentioned definition of "limit heating time" is also synonymous with the above-mentioned definition. Although it is redundant, the measurement method is shown below again.
(Method for measuring imaging ratio)
Using a mapping ratio measuring device compliant with JIS K7374:2007, the hard coat layer of organic glass with a hard coat layer is placed on a sample stand with the hard coat layer facing the light source, and measurement is performed at a reflection angle of 60° and a comb width of 2 mm.

The lower limit mapping ratio may be appropriately set according to the required level of the final product, but is preferably set to 90%. In the manufacturing method of the present invention, by using a conventionally known infrared heater as a heating means, this image mapping ratio can be sufficiently maintained in an organic glass molded product with a hard coat layer using a polycarbonate plate as a base material.

An example of setting the heating conditions is a case where the "bending treatment preparation temperature" is set to a predetermined temperature of 120°C or higher and 140°C or lower, and the surface temperature of the organic glass with a hard coat layer is set at the specified temperature. An example of a preferable setting of the heating conditions is an example in which the heating time to reach the predetermined temperature (the bending temperature) is 150 seconds or less. When a polycarbonate plate or other organic glass having a glass transition temperature Tg of up to about 150° C. is used as a substrate material, by heating under these conditions, the image mapping ratio can be maintained at approximately 90% or higher.

In addition, in cases where processing at a higher temperature is essential, such as when forming a shape with a large curvature (small bending radius) or when it is necessary to shorten the press time, for example, preparation for bending processing is required. When the temperature is set at a predetermined temperature of 150°C or more and 160°C or less, and the heating time until the surface temperature of the organic glass with a hard coat layer reaches the set predetermined temperature (the bending treatment temperature) An example of a preferable setting of the heating conditions is to set the heating condition to 200 seconds or less. When a polycarbonate plate or other organic glass having a glass transition temperature Tg of up to about 150° C. is used as a substrate material, by heating under these conditions, the image mapping ratio can be maintained at approximately 90% or more.

The radiant heat for heating in the heating step is preferably infrared radiant heat. Moreover, it is more preferable that this infrared ray is a mid-infrared ray having a center wavelength of 2.5 μm or more and 5.0 μm or less. When heating with infrared rays, a decrease in mapping ratio can be best suppressed by heating with radiant heat of mid-infrared rays.

[(e) Bending process]
This step is a step in which the heated organic glass 10 with a hard coat layer is bent and deformed into a desired shape to obtain a molded organic glass 100 with a hard coat layer having a curved surface or a bent portion. The bending method is not particularly limited, but one example is a manufacturing method in which a mold is applied to a portion softened by heating and the shape is created by bending it along the mold.

In this manufacturing method, by using the organic glass 10 with a hard coat layer of the present invention, even when bending is performed through a heating process, the image in the organic glass molded product 100 with a hard coat layer after the bending process is The reduction in rate can be sufficiently suppressed.

[Preparation of transfer sheet with hard coat layer]
A curable resin composition for forming a hard coat layer was applied to one surface of the base film to form an uncured resin layer. A hard coat layer (layer thickness: 1.5 μm) was formed by irradiating the uncured resin layer with an electron beam under the conditions of 90 kV and 7 Mrad (70 kGy) to crosslink and harden the uncured resin layer. (This step corresponds to an ionizing radiation curing step). A corona discharge treatment is performed on the surface of the hard coat layer opposite to the base film, and a primer layer forming resin composition is applied to form a primer layer (layer thickness: 2 μm). A heat seal layer (thickness: 1.5 μm) was formed by applying a heat seal layer forming resin composition to the laminate (this step corresponds to a laminate forming step). Through the above operations, a "transfer sheet with hard coat layer" was obtained, in which the base film, hard coat layer, primer layer, and heat seal layer were laminated in this order.

(Base film)
Product name: "Toyobo Ester Film E5101", manufactured by Toyobo Co., Ltd. (film made of polyethylene terephthalate resin (PET) with a thickness of 50 μm)

(Curable resin composition for forming hard coat layer)
Urethane acrylate (trade name "EBLF-2Y", manufactured by Showa Ink Industries, Ltd.): 100 parts by mass Curing agent (hexamethylene diisocyanate-based block isocyanate, manufactured by Showa Ink Industries, Ltd.): For 100 parts by mass of urethane acrylate, the following It was added in the amount shown in 1 (unit: parts by mass).

(Resin composition for forming primer layer)
Acrylic urethane resin (trade name "SG-63", manufactured by DIC Graphics Co., Ltd.): 100 parts by mass Curing agent (hexane methylene diisocyanate, manufactured by Dainichiseika Chemical Industry Co., Ltd.): 6 parts by mass

(Resin composition for forming heat seal layer)
Acrylic resin (product name “TM-R600(NT)K3”, manufactured by Dainichiseika Industries Co., Ltd.)

[Preparation of organic glass with hard coat layer]
A resin base made of a polycarbonate plate (300 mm x 300 mm, thickness 4.0 mm) was heated using a hot plate at 150°C. The hard coat film for transfer described above is placed on one side of the heated resin base so that the heat seal layer and the resin base are in contact with each other, and heat lamination is performed using a heated lamination roll at 190°C. "Organic glass" was obtained. In each production and each test described below, this "organic glass with a hard coat layer" was used in both the production and testing of Examples and Comparative Examples.

[Preparation of sample for evaluation of organic glass molded product with hard coat layer]
Using the above-mentioned "organic glass with hard coat layer", "samples for evaluation of organic glass molded products with hard coat layer" of Examples and Comparative Examples were manufactured. In each of the Examples and Comparative Examples, the same material was used in all cases, and only the heating conditions in the heating step were changed to produce different "samples for evaluation of organic glass molded products with hard coat layer".

[Heating process]
The above "organic glass with hard coat layer" was heated under the heating conditions shown in Table 1. Examples 1 to 4 used an infrared heater (center wavelength 5 μm, "Quick Ultra Thermo (QUT60)" (manufactured by TPR Shoji Co., Ltd.)) as a heating means, and Comparative Examples 1 to 3 used an oven ("DN610" (Yamato)) as a heating means. (manufactured by Kagaku Co., Ltd.)) was used. In each example, heating was continued until the surface temperature of the "organic glass with hard coat layer" reached the predetermined "bending treatment preparation temperature" in each example. In this heating step, it was confirmed using a radiation thermometer "AD-5611A (manufactured by A&D)" that the surface temperature of the "organic glass with hard coat layer" reached each bending treatment temperature.

[Test example: Image mapping measurement after heating process]
The image mapping ratios of Examples and Comparative Examples after the "heating step" were each measured by the following "Method for measuring imaging ratio". The results were as shown in Table 1.

(Method for measuring imaging ratio)
Measured using a mapping ratio measuring device "ICM-1T (manufactured by Suga Test Instruments Co., Ltd.)" (based on JIS K7374:2007). The hard coat layer of each "organic glass with hard coat layer" of Examples and Comparative Examples was placed on a sample stand facing the light source, and measurements were taken at a reflection angle of 60° and a comb width of 2 mm. Regarding the measurement after heating, the mapping ratio was measured after each "organic glass with hard coat layer" was naturally cooled to room temperature. The results were as shown in Table 1.

In Example 1 and Comparative Example 1, the "bending treatment preparation temperature" is the same, but the heating means and heating time to reach the same temperature are different, so there is a noticeable difference in the mapping rate (%) after heating. is occurring.

In Example 2 in which the "bending treatment preparation temperature" was set at 150° C., the mapping ratio after heating was 90% when the heating time was 200 seconds. From this result, if the predetermined lower limit mapping rate is 90%, the "limit heating time" when using this material and setting the "bending treatment preparation temperature" to 150 degrees Celsius is 200 seconds, and the heating By setting the heating conditions (e.g., infrared wavelength, intensity, etc.) so that the heating time is 200 seconds or less, the transparency of the organic glass molded product with a hard coat layer can be made to meet the requirements for the final product. can.

The results of Comparative Examples 2 and 3 show that it is virtually impossible to reach a sufficient "bending treatment temperature" and maintain the image mapping ratio by heating by convection heat.

From the above, it can be seen that the "method for manufacturing an organic glass molded product with a hard coat layer" of the present invention is a process that has an advantageous effect when performing bending work that involves heating at high temperatures.

10 Organic glass with hard coat layer 11 Organic glass substrate 12 Transfer sheet with hard coat layer 12a Base film 12b Hard coat layer 12c Primer layer 12d Heat seal layer 20 Extruder 30a, 30b Heater 41a, 41b Paper feed roll 42a, 42b Nip roll 43a, 43b Peeling roll 44a, 44b Paper discharge roll 100 Organic glass molded product with hard coat layer

Claims (1)

A method for producing an organic glass molded product with a hard coat layer, the method comprising:
a heating step of heating organic glass with a hard coat layer formed by thermally transferring the hard coat layer onto an organic glass substrate;
a bending step of bending the heated organic glass with a hard coat layer;
It includes,
In the heating step, heating is performed using radiant heat until the surface temperature of the organic glass with a hard coat layer reaches a predetermined bending preparation temperature.

Images