JPH07159903A - Transmission screen - Google Patents

Abstract

PURPOSE:To obtain a transmission screen having excellent embossing accuracy, scratching resistance, wear resistance, friction resistance and adhesion property of the embossed face and having uniform brightness all over the screen which is useful for a screen of a microfilm reader, projection TV and the like. CONSTITUTION:This screen is equipped with an observation plane and a projection plane and has a plastic film or sheet as the base body. The observation plane consists of an elastic polyester layer formed on the surface of the base body and has a fine rugged surface formed by embossing. This layer contains crystalline polyester having butylene terephthalate as the main repeating unit as a hard segment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmissive screen, and more specifically, it can form a fine uneven surface on an observation surface with a high degree of accuracy by embossing, is excellent in shape retention of the uneven surface, and scratches the surface of the screen. The present invention relates to an economical transmissive screen that is hard to be scratched and is economical.

[0002]

2. Description of the Related Art Transmissive screens are used as screens for microfilm readers, projection televisions and the like.

In a conventional transmissive screen, a screen made of a plastic film or sheet is used as a base material for the purpose of preventing the projected image from being difficult to see due to the external light reflected on the viewing surface or the light source being transparent. It is practiced to form fine irregularities and to apply a matte paint. And, as a method of applying this fine unevenness, heat is applied to the plastic film or sheet to soften it,
Then, a so-called embossing method of pressing the engraved metal roll and a sand mat processing method of spraying particles such as sand having high hardness to the surface of the film or sheet to give unevenness are performed.

However, although the embossing is performed in this embossing, the shape of the embossing causes a return deformation together with a relaxation of the internal strain due to the heat of the subsequent secondary processing such as bonding. However, there is a drawback that it is difficult to avoid returning to some extent. In addition, the sand mat processing has drawbacks that it requires a long processing step and increases cost, and that it is difficult to perform uniform processing over the entire screen, which causes uneven optical characteristics.

Further, it is difficult to obtain a sufficient matte effect by applying a matte paint, and in order to further improve it, if the particle size of the matte agent is increased and the amount of addition is increased, it will be other than matte. However, there is a drawback in that image characteristics such as contrast, brightness, and resolution of the optical properties of are adversely affected.

Further, as a measure for improving the heat resistance / holding property of the embossed shape and the transferability of the embossed shape, most of the conventional substrate films and sheets are made of a polymer having a high glass transition point. Therefore, it has high rigidity and hardness. Most of the substrates of this type, such as hard polyvinyl chloride film and polyester film, are easily scratched and scratched during handling and cleaning, and even when the depth is shallow, they stand out. This will adversely affect the image quality.

Therefore, Japanese Utility Model Application Laid-Open No. 2-39238 proposes to mix elastic rubber-like particles as a matting agent for matting paints with a binder resin and apply the mixture.
Costs increase due to procurement of rubber-like particles and coating work, and further measures are required.

[0008]

The inventors of the present invention have made earnest studies to develop a transmissive screen that solves the above problems. As a result, a plastic film or sheet is used as a base material, and an elastic polyester layer is formed on the surface of the observation surface side. Is provided
When the surface of the elastic polyester is embossed, a) the desired concavo-convex shape by the embossing is highly accurate,
It can be easily performed b) The shape retention of the fine irregularities shows excellent stability against heat during secondary processing and subsequent aging c) Due to this, matte and diffused light transmittance are improved. Excellent d) High total light transmittance and bright screen e) Scratch on the surface of the screen and scratches are not likely to occur, therefore the durability and handling of the screen are excellent f) Furthermore, an elastic polyester layer and a base film, In particular, the adhesiveness with the polyester film / sheet does not require special treatment, and high values can be obtained.As a comprehensive evaluation, it is possible to manufacture transmissive screens that are superior in terms of quality and cost than before. That is, the present invention has been achieved and the present invention has been achieved.

[0009]

That is, according to the present invention, in a transmissive screen having an observation surface and a projection surface and using a plastic film or sheet as a base material, the observation surface is provided on the surface of the base material. A transmissive screen comprising a layer of elastic polyester having a finely textured surface formed by embossing and having a crystalline segment of butylene terephthalate as a main repeating unit as a hard segment.

In the present invention, examples of the plastic film or sheet include polyester (eg polyethylene terephthalate, polyethylene-2,6-naphthalate etc.), polyvinyl chloride, polyolefin (eg polyethylene, polypropylene, polymethylpentene etc.), polyamide (eg Nylon 6, Nylon 66
Etc.), polyacrylonitrile, polymethylmethacrylate, polyarylate, polyphenylsulfide, polysulfone, polyethersulfone, polyetherimide, polyvinylidene chloride, polycarbonate, and a film or sheet made of a plastic such as an acetate resin. Further, a film or sheet obtained by laminating two or more of these films or sheets can also be used. Among these, polyester film or sheet, especially polyethylene terephthalate film or sheet, has physical properties (for example, tensile strength, dimensional stability, heat resistance, cold resistance, etc.), processability (for example, peel strength at lamination, processability in lamination, embossing process, etc.). ), Price, etc. are preferable.

A diffusing agent, such as an inorganic substance (powder such as silica or aluminum hydroxide), for the purpose of increasing the diffused light transmittance is added to these plastic films or sheets, and as a transmission screen. Additives for the purpose of flame retardant, antistatic agent, antifungal agent, slippery agent, pigment, reinforcing material, etc., which do not impair the performance, may be contained.

In the present invention, the elastic polyester is an elastic polyester having a hard segment of crystalline polyester having butylene terephthalate as a main repeating unit. As the crystalline polyester, polybutylene terephthalate or copolymerized polyester in which butylene terephthalate accounts for 70% or more of all repeating units is preferable.

As the soft segment of the elastic polyester, for example, an aliphatic polyether such as polytetramethylene glycol, an aromatic dicarboxylic acid (terephthalic acid,
A non-crystalline or non-crystalline copolyester of an aliphatic dicarboxylic acid having 4 to 12 carbon atoms (such as isophthalic acid) (for example, adipic acid, pimelic acid, etc.) and a glycol having 2 to 6 carbon atoms is preferable.

A specific method for producing such elastic polyester (polyester elastomer) is, for example, Japanese Patent Publication No.
The elastic polyester used in the present invention is not limited to these, although detailed descriptions are given in JP-A No. 0-35365 and JP-A No. 58-141236.

In the present invention, the first reason for using a crystalline polyester having butylene terephthalate as a main repeating unit (hereinafter sometimes abbreviated as PBT type crystalline polyester) in the hard segment of the elastic polyester is similar to the design. The ability to form an embossed surface. Generally, in an elastic polymer that is flexible at room temperature, the return deformation occurs with time even after embossing, and the temperature rise during heating in the subsequent secondary processing causes a large deformation of the embossed shape. It is difficult to maintain the shape as designed, and since the shape has a direct effect on the optical properties, which are the basic physical properties, it is not suitable for screen applications. It has been considered difficult to apply the same material at the same time as that for embossing to make it difficult to attach. Therefore, it can be said that the elastic polyester can form an embossed surface close to the design, which is a special effect.

The second reason is that the embossed surface has excellent shape-retaining property even when the temperature rises in the subsequent secondary processing step during heating, and the workability becomes good in connection therewith. For this, the melting point of polybutylene terephthalate, which is a hard segment of elastic polyester, is as high as 200 to 210 ° C., and the amount of hard segment of polybutylene terephthalate is about 30 wt%,
Its heat resistance (softening point) is as high as 150 ° C or higher, even if it is affected to some extent by the composition of the soft segment,
Furthermore, it is considered that the crystallization rate of the hard segment is high.

That is, when the elastic polyester film-like melt is extruded into a plastic film or sheet, for example, a polyester film, the engraved pattern of the embossing roll, which has been cooled and adjusted, is immediately transferred, and at the same time, crystallization is rapidly advanced. However, it is considered that this suppresses the return deformation in the embossing process, and at the same time, its high melting point and softening point greatly contribute to the heat resistance and aging resistance of the shape retention.

The third reason is that it is easy to obtain an embossed shape close to the design (engraving pattern of the embossing roll).
The expected optical properties (matte, diffusive, transmissivity) should be uniform over the entire surface.

The fourth reason is that when a polyester film or sheet is used as the base film or sheet, the adhesion between the two is excellent and lamination by extrusion coating method,
In the embossing, it is possible to obtain a high adhesion strength of 500 g / 15 mm width or more, which can be practically used, only by subjecting the polyester film side to corona treatment.

The fifth reason is that the thickness of the elastic polyester layer is as thick as 20 μm or more and scratches and scratches are less likely to occur.
In addition, even if a shocking external force is applied, the stress is absorbed and relieved, so that the ability is fully exhibited.

The sixth reason is that the plastic film or sheet alone, for example, the polyester film or sheet alone, is hard to disappear once the fold is formed,
It has drawbacks for screens such as low tear propagation resistance and high rigidity (poor texture), but this drawback is solved by laminating elastic polyester on one side (observation side of screen) or both sides. At the same time, the texture and flexibility can be adjusted by the thickness.

As described above, the elastic polyester constituting one screen has many important functions. The block copolymerization ratio of the (I) hard segment and the (II) soft segment is as follows. The ratio of the hard segment of polybutylene terephthalate is 20 to 6
It is preferably in the range of 0% by weight. This ratio is 20
If it is less than 5% by weight, heat resistance and shape retention are deteriorated.
If it exceeds 0% by weight, the rigidity becomes high, which is not preferable. Further, the polybutylene terephthalate component in the hard segment is preferably a copolymer of 100% (homopolymer) to 70% or more, because when it is less than 70%, the crystallinity (crystallinity, speed) decreases, This is because the role of the hard segment is lowered and the heat resistance and the embossed shape retention are impaired. From the viewpoint of function and cost, a hard segment composition of 100% polybutylene terephthalate is preferable.

The glass transition point of the elastic polyester is
Although not particularly restricted, it is preferably 10 ° C or lower. This is because the probability that the operating environment temperature of the screen is lower, especially in winter, becomes higher, and the elasticity disappears at the temperature below the glass transition point, so that the scratch resistance and the handleability of the screen deteriorate. The glass transition point is adjusted mainly by selecting the composition of the soft segment.

In the present invention, the elastic polyester includes a light diffusing agent, a matting agent, a slippery agent, a pigment, an antistatic agent, a flame retardant, an antifungal agent, a strengthening agent, which does not impair image characteristics such as light transmittance. Fillers, pigments and the like may be added.

In the present invention, the elastic polyester is laminated on one surface (observation surface) or both surfaces (observation surface and projection surface) of the plastic film or sheet. The thickness of the lamination is the presence or absence of the above-mentioned additives and the optical properties thereof. , The form of embossing, the desired flexibility of the screen, etc. Generally, it is 20 μm or more. The elastic polyester is highly transparent when it is not added, and has little dependence on the optical properties depending on the thickness. Therefore, when it is used alone, the range of the thickness is large. However, when a light diffusing agent is added, the light diffusing agent is adjusted according to the relationship with the image resolution, brightness, and the diffuse transmittance of the plastic film or sheet of the substrate.

When the elastic polyester is laminated on the projection side as well, in addition to the embossing of fine irregularities similar to the observation surface, the processing for the purpose of providing a fullnel lens, a lenticular lens, etc. By covering the base film or sheet, scratches,
In some cases, the purpose is to prevent scratches and adjust the texture of the screen.

In the present invention, it is necessary to emboss the elastic polyester layer laminated on at least the observation surface of the base material to form fine irregularities on the surface.

As this laminating / embossing method, the following general methods can be applied.

(1) A method in which elastic polyester is melt-extruded into a film shape by an extruder and laminated on the surface of a plastic film, and at the same time as or immediately after that, a so-called embossing roll engraved is pressed. This method is the most economical
It is also effective in terms of quality.

When a polyester film or sheet is used as the base film or sheet, the corona treatment, which is generally widely used, is enough to withstand a high level of adhesion strength (500 g / 15 mm).
The above is the advantage. Polyester film or sheet is relatively inexpensive and has various properties, so it is also used for the base of screens with a composite structure, but it does not require undercoating when laminated with elastic polyester. It is advantageous in terms of cost reduction and work environment. In order to obtain higher adhesion strength, a combination of corona treatment and subsequent application of an anchor agent can be adopted. In this case, an isocyanate-based anchor agent is suitable as the anchor agent.

(2) The elastic polyester is once formed into a film by a melt extrusion method, and then laminated with a plastic film or a sheet or a woven fabric by a laminating device, and then heated to 150 to 200 ° C. to obtain the elastic polyester. A method of pressing the embossing roll while the layer is softened can be adopted. This method leads to cost increase, but is suitable for small lot production.

The transmissive screen-processed film or sheet thus produced is cut into desired dimensions,
The final shape of the transmissive screen is obtained through secondary processing such as frame processing.

[0033]

EXAMPLES The present invention will be further described below with reference to examples.

Example 1 Polyethylene terephthalate to which 0.8% by weight of silica having an average particle diameter of 3.0 μm was added for the purpose of a light diffusing agent and a lubricant was melt-extruded and rapidly solidified into an unstretched film. The unstretched film is sequentially biaxially stretched (longitudinal stretching ratio 2.8 times, transverse stretching ratio 3.0 times),
Further, one surface was subjected to corona treatment to obtain a biaxially oriented polyester film having a thickness of 75 μm. The total light transmittance of this film was 92%, the haze was 32%, the gloss was high, and the surface tension of the corona-treated surface was 54 dyn / cm.

As the elastic polyester, the hard segment (I) is polybutylene terephthalate (30% by weight), the soft segment (II) is isophthalic acid (80 mol%), sebacic acid (20 mol%) and hexamethylene glycol (100%). Mol%) copolymer (70% by weight)
A block copolymer consisting of and was prepared. The glass transition temperature is -9 ° C, the melting point is 205 ° C, JISK63
The impact resilience measured at 01 (23 ° C.) was 61%. This elastic polymer does not contain additives such as lubricants, flame retardants and antistatic agents. When this elastic polymer is melt extruded and formed into a film, the thickness is 100 μm.
The haze of the film of m was 0.9%.

The above-mentioned elastic polymer chip was dried at 120 ° C. for 4 hours, then fed to the hopper of a 95 mmφ extruder,
An embossing roll (about 35 ° C.) which was melt extruded into a film at 30 ° C., laminated on the corona discharge treated surface of the biaxially oriented polyester film with a thickness of 100 μm, and cooled.
Was pressed to perform embossing (processing speed 30 m /
min).

A transmissive screen having an embossed surface as an observation surface was prepared using the obtained laminated embossed film.

The characteristics of this laminated embossed film are shown in Table 1. This film is a translucent film with an unembossed surface having a matt appearance, and has a high total light transmittance, a bright screen, and a cloudy surface. The degree (a measure of diffuse transmitted light) is also an appropriate value, and it has excellent optical properties as a transmissive screen with low gloss and no peripheral reflection phenomenon. At the same time, the observation surface is coated with an elastic polymer and embossed. Is fully satisfied with the function of not scratching or scratching.

[0039]

[Table 1]

[0040]

According to the present invention, scratches and scratches are greatly improved as compared with the conventional ones, there is no phenomenon of the surrounding objects reflected on the screen screen, and the shape of the fine embossing of the embossing is formed. It is possible to provide a transmissive screen which is excellent in retainability, has various excellent properties such as imparting appropriate flexibility as a screen, and crease resistance, and is manufactured at low cost.

Claims (3)

[Claims] 1. A transmissive screen having an observation surface and a projection surface and using a plastic film or sheet as a base material, wherein the observation surface has a fine uneven surface by embossing provided on the surface of the base material. A transmissive screen comprising a layer of elastic polyester having a hard segment of crystalline polyester having butylene terephthalate as a main repeating unit. 2. The transmissive screen according to claim 1, wherein the crystalline polyester constituting the hard segment is polybutylene terephthalate or copolymerized polyester in which butylene terephthalate accounts for 70% or more of all repeating units. 3. The transmissive screen according to claim 1, wherein the plastic film or sheet is a polyethylene terephthalate film or sheet or a polyethylene-2,6-naphthalate film or sheet.