JPH10140043A - Anti-reflective paint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject coating capable of excellently preventing reflections by dispersing a specific amount of fine particles of a synthetic resin having a specific particle size and fine particles of carbon black in a specific ratio in a synthetic resin binder. SOLUTION: This coating for preventing reflections is obtained by dispersing (B) fine particles of a synthetic resin having 15-50μm average particle size and (C) fine particles of carbon black having <=1μm average particle size in (A) 100 pts.wt. of a synthetic resin binder in (10:1)-(1:5) weight ratio and in 20-500 pts.wt. sum total of the components B and C. As the component A, specifically a heat-curing acrylic resin is preferable. As the component B, fine particles of an acrylic resin are preferable. This coating is used in a direct coating on a place to be prevented from reflections.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel anti-reflection coating, and more particularly, to an effective anti-reflection coating which is effective for shielding light from various optical devices such as cameras, copiers and developing machines. It relates to paint to prevent.

[0002]

2. Description of the Related Art In general, various obstacles due to reflection of incident light pose a problem in optical devices such as cameras, copiers and developing machines. For example, in the case of a camera, the incident light is reflected on the inner wall and adversely affects the film, or the light from the light source is reflected on the camera inner wall and enters the finder optical path to make it difficult to see the finder visual field image. In a copying machine, when an image is formed on a photoconductor, light generated from the inside of the copying machine is reflected inside the copying machine, and makes the image on the photoconductor unclear. Also, in a developing machine, there is a problem that incident light is reflected on an inner wall and is exposed to a film being developed, or when printing on photographic paper, a photograph becomes out of focus and becomes unclear. Occurs.

In order to solve such a problem, in the case of various optical devices, especially cameras, a camera body, a shutter case, a cover, and the like are formed of a black matte plastic material, or a flocking paper is attached. Measures have been taken.

[0004] However, the method of forming the inner wall of an optical device with a black matte plastic material is technically complicated because a portion related to light reflection that cannot be predicted at the design stage is processed only at that portion. It is inevitable that the cost is high, and furthermore, it has disadvantages such as not being able to obtain a satisfactory antireflection effect for light incident at a low angle, and in the method of attaching flocking paper,
In addition to thickening over the entire surface, it has drawbacks such as adhesion of surrounding dust and re-adhesion of hair falling off from the flocking paper, resulting in contamination.

[0005] On the other hand, in recent years, with the trend of miniaturization of cameras and the like, the demand for miniaturization of each component has been further increased, and as a result, the inner wall surface for anti-reflection has become thinner. What does not generate garbage has been demanded.

[0006]

Under such circumstances, the present invention has excellent anti-reflection properties, especially anti-reflection properties and light-shielding properties for light incident at a low angle, and generates dust. The object of the present invention is to provide an antireflection coating suitable for antireflection of optical equipment without causing the above.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to develop an antireflection coating having excellent functions as described above, and as a result, a synthetic resin binder having a specific particle size has been obtained. It has been found that the object can be achieved by dispersing the resin fine particles and the carbon black fine particles at a predetermined ratio and in a predetermined amount, and based on this finding, the present invention has been completed.

That is, according to the present invention, (A) synthetic resin fine particles having an average particle diameter of 15 to 50 μm and (B) carbon black fine particles having an average particle diameter of 1 μm or less are mixed in 100 parts by weight of a synthetic resin binder. The present invention provides an antireflection coating characterized by being dispersed at a ratio of 1: 1 to 1: 5 and in a total amount of 20 to 500 parts by weight.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The antireflection coating of the present invention contains a synthetic resin binder, (A) fine particles of synthetic resin and (B) fine particles of carbon black. A curable resin or a thermoplastic resin that is cured by light or light is used.

In the present invention, thermosetting resins such as acrylic, urethane, phenol, melamine, urea, diallyl phthalate, polyester, epoxy and alkyd resins are used as the synthetic resin binder. A curable resin is preferably used. These may be used alone or in combination of two or more. Among these, a thermosetting acrylic resin is particularly preferable because of its excellent heat resistance, moisture resistance, solvent resistance, surface hardness and the like. Examples of the thermoplastic resin include a thermoplastic acrylic resin, a vinyl chloride resin, a butyral resin, and a styrene / butadiene resin.

The synthetic resin binder may contain a crosslinking agent, if desired. Examples of the crosslinking agent include a urea resin, a melamine resin, an isocyanate resin, an aziridine resin, an oxazoline resin, and the like. Particularly, a melamine resin is preferable because it has excellent heat resistance, solvent resistance, and coating film hardness. The mixing ratio of the crosslinking agent is usually in the range of 10 to 50% by weight based on the synthetic resin binder. If the amount is less than this, desired properties cannot be obtained, and if it is more than this, the coating film is too hard and brittle.

Further, when a crosslinking agent is used, it is desirable to use a reaction catalyst in combination in order to accelerate the reaction.
Examples of the reaction catalyst include ammonia and ammonium chloride. The mixing ratio of the reaction catalyst is usually in the range of 0.1 to 10% by weight based on the crosslinking agent.

Next, examples of the synthetic resin fine particles of the component (A) include fine particles of melamine resin, benzoguanamine resin, benzoguanamine / melamine / formalin condensate, acrylic resin, urethane resin, styrene resin and the like. These may be used alone or in combination of two or more. Among them, acrylic resin is particularly preferable because it can diffusely reflect light on the surface to prevent linear reflection of incident light. The shape of the synthetic resin fine particles is not particularly limited, but is preferably spherical from the viewpoint of improving the flow characteristics of the coating material and providing excellent coating suitability.

The average particle size of the synthetic resin fine particles is 15 to
It needs to be in the range of 50 μm. When the average particle diameter is less than 15 μm, the reflectance at a low angle increases, and when the average particle diameter exceeds 50 μm, the dispersion stability of the coating material deteriorates,
Synthetic resin particles are likely to settle. The average particle diameter of the synthetic resin fine particles is particularly preferably in the range of 20 to 40 μm from the viewpoints of suppression of reflectance at a low angle and dispersion stability of the paint.

On the other hand, the carbon black fine particles of the component (B) need to have an average particle diameter of 1 μm or less. When the average particle size exceeds 1 μm, the difference in particle size from the component (A) decreases, and the surface area decreases.
Since the carbon packing density is reduced, the light absorption ability is reduced, and the antireflection property is deteriorated. From the viewpoint of antireflection properties, the particularly preferred average particle diameter of the carbon black fine particles is 0.5 μm or less.

In the present invention, the compounding ratio of the synthetic resin fine particles of the component (A) and the carbon black fine particles of the component (B) must be in the range of 10: 1 to 1: 5 by weight. is there. When the proportion of the component (A) is less than the above range, the irregular reflection efficiency of the coating film surface is deteriorated, and the hardness of the coating film is reduced. When the ratio is large, the light absorbency is deteriorated, the degree of blackness is reduced, and the appearance is reduced. Be impaired. From the viewpoint of the irregular reflection efficiency of the coating film surface, the hardness of the coating film, the appearance, and the like, the particularly preferable mixing ratio of the components (A) and (B) is in the range of 5: 1 to 1: 2.

In the paint of the present invention, (A)
It is necessary to mix and disperse the component and the component (B) in such a ratio that the total amount thereof becomes 20 to 500 parts by weight with respect to 100 parts by weight of the synthetic resin binder.
If the amount is less than 20 parts by weight, the adhesion to the substrate is poor, and the reflectance may be high. If the amount is more than 500 parts by weight, the coating film tends to be brittle. From the viewpoints of the properties of the coating film and the antireflection properties, the preferable amount of the components (A) and (B) is in the range of 50 to 200 parts by weight based on 100 parts by weight of the synthetic resin binder.

The antireflection coating of the present invention is prepared by suspending a synthetic resin binder, component (A) and component (B) in water or an organic solvent or a mixture of water and an organic solvent. Can be. At this time, if necessary, various additives conventionally used, for example, a thickener, a dispersant,
A coloring agent, an antifoaming agent and the like can be blended. In particular, a water-soluble acrylic resin is preferable because it provides an excellent thickening effect and a dispersing effect to the paint. When this water-soluble acrylic resin is compounded, its mixing ratio is usually in the range of 0.5 to 5% by weight based on the total amount of the synthetic resin binder, the component (A) and the component (B). 0.5% by weight
If it is less than 3, the thickening effect is insufficient, and the effect of improving coating suitability is not sufficiently exhibited. If it exceeds 5% by weight, the liquid viscosity becomes too high, and the coating suitability deteriorates.

The antireflection coating of the present invention is used by directly applying it to a place where antireflection is to be performed, or by applying it on a base material to form an antireflection material and then attaching it. You.

[0020]

When the anti-reflection coating of the present invention is used to form an anti-reflection layer, this layer has excellent light-shielding properties and anti-reflection properties, particularly excellent anti-reflection properties for light incident at low angles. Further, since it is thinner than flocked paper and does not cause contamination due to hair loss or dust adhesion unlike flocked paper, it is suitable as an antireflection coating for internal surfaces that adheres to the inner wall of various optical devices such as cameras.

[0021]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, the physical properties in each example were measured by the following methods. (1) Gloss (%): Measured using a gloss meter according to JIS Z8741 (2) Density (visible): Macbath TD
Measured by 904

Examples 1 to 3 19.5 parts by weight of a thermosetting acrylic emulsion (Movinyl 747, solid content: 43% by weight; manufactured by Hoechst Gosei Co., Ltd.), and carbon black fine particles having an average particle diameter of 1 μm or less (GP Black # 4613, 38.6 parts by weight of acrylic resin particles (MBX-30; manufactured by Sekisui Chemical Co., Ltd.) having a solid content concentration of 12% by weight;
3.5 parts by weight, water-soluble acrylic resin (AC-10H, solid content concentration 20% by weight; Nippon Junyaku Co., Ltd.) 3.6 parts by weight, crosslinking agent (melamine resin, Sumitec Resin M-3, solid content concentration) 80% by weight; 4.5 parts by weight of Sumitomo Chemical Co., Ltd., 4.8 parts by weight of ammonia (5% by weight aqueous solution), 0.9 parts by weight of ammonium chloride (20% by weight aqueous solution), ethanol 10
By weight, 39 parts by weight of water were mixed to prepare an antireflection coating. Two kinds of antireflection paints were prepared in the same manner as described above except that the amounts of the above components were changed to the amounts shown in Table 1. The above three kinds of antireflection paints are applied to one side of a 100 μm-thick polyethylene terephthalate film with a wire bar, and heated at 130 ° C. for 5 minutes to a thickness of 40 μm.
Was formed. Table 2 shows the physical properties of the antireflection layer thus obtained.

Comparative Example 1 In Example 1, the average particle size of the acrylic resin particles was 1
An antireflection layer was formed in the same manner as in Example 1 except that the thickness was changed to 0 μm. Table 2 shows the physical properties of this product.

Comparative Examples 2 and 3 An antireflection layer was formed in the same manner as in Example 1 except that the coating composition shown in Table 1 was used as the antireflection paint. Table 2 shows the physical properties of this product.

[0025]

[Table 1]

[Note] 1) Thermosetting acrylic emulsion (Movinyl 74)
7, solid content concentration 43% by weight; manufactured by Hoechst Gosei Co., Ltd.) 2) Acrylic resin particles (MBX-
30; manufactured by Sekisui Plastics Co., Ltd.) 3) Fine particles of carbon black having an average particle diameter of 1 μm or less (GP Black # 4613, solid content concentration: 12% by weight; manufactured by Mikuni Color Co., Ltd.) 4) Crosslinking agents (melamine resin, Sumitec Resin M) -3,
Solid content concentration 80% by weight; manufactured by Sumitomo Chemical Co., Ltd.) 5) Water-soluble acrylic resin (AC-10H, solid content concentration 2)
0% by weight; Nippon Junyaku Co., Ltd.) 6) Ammonia (5% by weight aqueous solution) 7) Ammonium chloride (20% by weight aqueous solution)

[0027]

[Table 2]

As can be seen from Table 2, in Comparative Examples 1 to 3, the gloss was high at any angle, or the gloss was low at the high angle but high at the low angle. Examples 1 to 3 have low gloss at low angles and low gloss at any angles.

Claims (3)

[Claims] 1. A synthetic resin binder having 100 parts by weight,
(A) synthetic resin fine particles having an average particle diameter of 15 to 50 μm and (B) carbon black fine particles having an average particle diameter of 1 μm or less in a weight ratio of 10: 1 to 1: 5, and the total amount thereof is 20 to An antireflection coating, wherein the coating is dispersed so as to be 500 parts by weight. 2. The antireflection coating according to claim 1, wherein the synthetic resin binder is an acrylic resin. 3. The antireflection coating according to claim 1, wherein the synthetic resin binder contains a melamine resin as a crosslinking agent.