Transparent laminate film

Abstract

A coat layer and a substrate layer are combined to prepare a transparent laminate film; the coat layer has a surface with a maximum height of rolling circle waviness profile (W.sub.EM) in accordance with JIS B0610 of 5 to 15 m and an arithmetic average roughness (Ra) of not less than 0.5 m. The transparent laminate film provides a comfortable writing experience and a reduced abrasion of a pen tip. The coat layer may have the surface with the arithmetic average roughness (Ra) of 0.5 to 5 m. The coat layer may contain particles and a binder component. The binder component may comprise a polyfunctional (meth)acrylate, and a urethane (meth)acrylate and/or a thermoplastic elastomer. The transparent laminate film may have a total light transmittance of not less than 85%. The transparent laminate film may be disposed on a surface of a display of a pen-input device.

Claims

1. A display having a surface with a maximum height of rolling circle waviness profile (W.sub.EM) in accordance with Japanese Industrial Standards (JIS) B0610 of 5 to 15 m and an arithmetic average roughness (Ra) of not less than 0.5 m.

2. The display according to claim 1, which comprises a transparent laminate film comprising a substrate layer and a coat layer, wherein the coat layer has a surface with a maximum height of rolling circle waviness profile (W.sub.EM) in accordance with Japanese Industrial Standards (JIS) B0610 of 5 to 15 m and an arithmetic average roughness (Ra) of not less than 0.5 m.

3. The display according to claim 2, wherein the coat layer has the surface with the arithmetic average roughness (Ra) of 0.5 to 5 m.

4. The display according to claim 2, wherein the transparent laminate film has a total light transmittance of not less than 85% and a haze of 1 to 30%.

5. The display according to claim 1, which is a transmissive display.

6. The display according to claim 1, which is a touch screen display, wherein the transparent laminate film is disposed on a surface of the touch screen display.

7. A pen-input device comprising the display recited in claim 1.

8. The pen-input device according to claim 7, which uses a pen having a plastic pen tip.

Description

EXAMPLES

(1) The following examples are intended to describe this invention in further detail and should by no means be interpreted as defining the scope of the invention. The transparent laminate films obtained in Examples and Comparative Examples were evaluated for the following items.

(2) [Thickness of Coat Layer (Flat Portion)]

(3) The thickness of the coat layer was measured at any 10 points using an optical thickness meter, and the average value was calculated.

(4) [Haze and Total Light Transmittance]

(5) Using a haze meter (trade name NDH-5000W manufactured by Nippon Denshoku Industries Co., Ltd.), the total light transmittance was measured in accordance with JIS K7361 and the haze was measured in accordance with JIS K7136. The transparent laminate film was disposed so as to face the coat layer toward a beam receiver, and the measurement of the haze was carried out.

(6) [Arithmetic Average Roughness Ra]

(7) In accordance with JIS B0601, the arithmetic average roughness Ra was measured using a surface texture and contour measuring instrument (SURFCOM 570A manufactured by Tokyo Seimitsu Co., Ltd.).

(8) [Maximum Height of Rolling Circle Waviness Profile (W.sub.EM)]

(9) In accordance with JIS B0610, the maximum height of rolling circle waviness profile (W.sub.Em) was measured using a surface texture and contour measuring instrument (SURFCOM 570A manufactured by Tokyo Seimitsu Co., Ltd.) under the following conditions.

(10) Stylus: Waviness (0102505)

(11) Specification of stylus: 800 mR, ruby

(12) Driving speed: 3 mm/s

(13) f reduction cut-off value: 8 mm

(14) Measuring length: 15 mm

(15) [Pencil Hardness]

(16) The pencil hardness was measured by applying a load of 7.4 N in accordance with JIS K5400.

(17) [Steel Wool (SW) Durability]

(18) Using a steel wool durability tester provided with a stick 1.0 cm in diameter covered with a #0000 steel wool, the steel wool was allowed to go back and forth on the surface of the coat layer 10 times (at velocity: 10 cm/s) under a constant load (a load of 100 g). Then the transparent laminate film was attached to a black acrylic plate with the use of an optical agglutinant. The state of the surface was observed under the light of a fluorescent tube provided with a three-band fluorescent lamp, and the number of scratches was counted. The SW durability was evaluated on the basis of the following criteria.

(19) A: No scratches appear.

(20) B: One or two scratches appear.

(21) C: Three or more scratches appear.

(22) [Pen Tip Abrasion Resistance]

(23) Using a sliding tester for touch panel, a digital pen for Nintendo DS (registered trademark), which is a mobile game machine, was allowed to go back and forth 50 mm on the sample 10000 times under a load of 500 g. Thereafter, the abrasion length of the pen tip was measured.

(24) [Comfortable Writing Experience]

(25) The surface of the coat layer was evaluated for a comfortable writing experience with a digital pen for Nintendo DS (registered trademark) by 8 subjects on the basis of the following criteria.

(26) A: Five or more subjects judged the film to be comfortable to write on, similar to a pencil-on-paper writing experience.

(27) B: Four or less subjects judged the film to be comfortable to write on, similar to a pencil-on-paper writing experience.

(28) [Material]

(29) Transparent PET substrate film: A4300 manufactured by Toyobo Co., Ltd., thickness: 100 m

(30) Hardcoat film A: KB film N10 manufactured by Kimoto Co., Ltd.

(31) Hardcoat film B: KB film N30 manufactured by Kimoto Co., Ltd.

(32) Polyfunctional acrylate: polyfunctional acrylic UV-curable monomer (dipentaerythritol penta- to hexa-acrylate, DPHA manufactured by Daicel-Allnex Ltd.

(33) Urethane acrylate: polyfunctional urethane acrylate, PU3210 manufactured by Miwon Specialty Chemical Co., Ltd.

(34) Urethane elastomer: polyurethane elastomer, DAIALLOMER EX002 manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.

(35) Cellulose derivative: cellulose acetate propionate, CAP manufactured by Eastman Chemical Company, Ltd.

(36) Acrylic particle (5 m): FH-5005 manufactured by Toyobo Co., Ltd., average particle size: 5 m, crosslinked polymethacrylate particles

(37) Acrylic particle (8 m): SSX-108 manufactured by Sekisui Plastics Co., Ltd., average particle size: 8 m, crosslinked polymethacrylate particles

(38) Acrylic particle (10 m): FH-S010 manufactured by Toyobo Co., Ltd., average particle size: 10 m, crosslinked polymethacrylate particles

(39) Acrylic particle (15 m): FH-5015 manufactured by Toyobo Co., Ltd., average particle size: 15 m, crosslinked polymethacrylate particles

(40) Acrylic particle (20 m): SSX-120 manufactured by Sekisui Plastics Co., Ltd., average particle size: 20 m, crosslinked polymethacrylate particles

(41) Initiator A: photopolymerization initiator, IRGACURE 184 manufactured by BASF Japan Ltd.

(42) Initiator B: photopolymerization initiator, IRGACURE 907 manufactured by BASF Japan Ltd.

Examples 1 to 3 and Comparative Examples 4 to 5

(43) In a mixed solvent of methyl ethyl ketone, methoxypropanol, and 1-butanol [methyl ethyl ketone/methoxypropanol/1-butanol=4/3/3 (volume ratio)], resin components and particles combined at a proportion shown in Table 1, and 1.0 part by weight of the initiator A and 1.0 part by weight of the initiator B relative to 80 parts by weight of the polyfunctional acrylate were blended to prepare a liquid composition having a total material concentration of 30% by weight.

Examples 4 to 5 and Comparative Example 3

(44) In a mixed solvent of ethyl acetate and isopropanol [ethyl acetate/isopropanol=6/4 (volume ratio)], resin components and particles combined at a proportion shown in Table 1, and 2.5 parts by weight of the initiator A and 2.5 parts by weight of the initiator B relative to 80 parts by weight of the polyfunctional acrylate (50 parts by weight of the polyfunctional acrylate for Comparative Example 3) were blended to prepare a liquid composition having a total material concentration of 25% by weight.

(45) Each of these liquid compositions was cast on a transparent PET substrate film with the use of any wire bar of #12 to #36 according to a desired film thickness, and then allowed to stand for one minute in an oven at 80 C. Thereafter, the coated film passed through an ultraviolet irradiation equipment (manufactured by Ushio Inc., a high-pressure mercury lamp, dose of ultraviolet ray: 500 mJ/cm.sup.2) for ultraviolet curing treatment to form a coat layer (dry thickness: 7 to 13 m).

Comparative Example 1

(46) As a transparent laminate film, a commercially available hardcoat film A was used.

Comparative Example 2

(47) As a transparent laminate film, a commercially available hardcoat film B was used.

(48) Table 1 shows the evaluation results of the haze, total light transmittance, pencil hardness, SW durability, pen tip abrasion resistance, and comfortable writing experience of the resulting transparent laminate films and commercially available hardcoat films.

(49) [Table 1]

(50) TABLE-US-00001 TABLE 1 Examples Comparative Examples 1 2 3 4 5 1 2 3 4 5 Composition Polyfunctional acrylate 80 80 80 80 80 50 100 80 <parts by weight> Urethane acrylate 20 20 20 20 Urethane elastomer 20 20 50 Cellulose derivative 7 7 7 Acrylic particle (5 m) 5 Acrylic particle (8 m) 2 Acrylic particle (10 m) 2 2 4 Acrylic particle (15 m) 2 1 1 3 2.5 Acrylic particle (20 m) 5 1 Thickness of coat layer (m) 9 7 9 12 12 13 10 12 Ra (m) 0.89 0.86 1.26 0.53 0.69 0.23 0.36 0.26 2.49 1.92 W.sub.EM (m) 5.56 7.60 9.2 8.48 9.13 10.68 12.32 8.57 27.48 16.8 Haze (%) 16.2 20.1 18.4 6.39 12.7 27.0 17.5 15.9 Total light transmittance (%) 90.3 90.4 90.5 91.2 91.4 91.0 90.6 90.1 Pencil hardness 3H 3H 3H H H F 3H 3H SW durability A A A A A C A A Pen tip abrasion resistance (m) 3 4 4 2 3 20 11 Comfortable writing experience A A A A A B B B A A

(51) As apparent from the results in Table 1, the transparent laminate films of Examples have excellent optical characteristics and a small abrasion of the pen tip, as well as provide a comfortable writing experience. In particular, the transparent laminate film of Example 4 has the smallest abrasion of the pen tip, and in addition, satisfies a comfortable writing experience, a low haze, and better visibility. In contrast, the transparent laminate films of Comparative Examples cannot satisfy the characteristics mentioned above simultaneously.

INDUSTRIAL APPLICABILITY

(52) According to the present invention, the transparent laminate film is utilizable for a variety of apparatuses, for example, a pen-input touch screen (in particular, a projected capacitive touch screen of ITO grid system) and a computer pointing device (such as a pen tablet). The pen-input touch screen is used, for example, in combination with a display (e.g., a liquid crystal display, a plasma display, and an organic or inorganic EL display) in a display unit of an electric or electronic equipment or precision equipment, such as a PC, a television, a mobile phone or a smartphone, an electronic paper, a game console, a mobile device, a clock or a watch, or an electronic calculator. Among them, the transparent laminate film, which has an excellent transparency and a low haze, provides an excellent visibility and is thus useful for a transmissive display. Further, the transparent laminate film offers a comfortable writing experience with even a fine-point pen and is thus particularly useful for a transmissive display provided with an electromagnetic induction type pen input system.