JPS6250199A - Sheet-shaped article for writing - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to improvements in writing sheets, and more particularly to improvements in the writability and erasability of writing surfaces such as electronic blackboards and whiteboards.

[Conventional technology]

Conventionally, sheet-like materials that can be written on and erased using commercially available whiteboard markers (for example, 1 Whiteboard Marker PM-91" Kokuyo-Ken, "Sakura Whiteboard Marker WBK" manufactured by Sakura Crevasse) include polyethylene,
Films such as polypropylene and polyvinyl chloride, laminates using them, and enamel products are used, but in recent years, laminates of ethylene/tetrafluoroethylene copolymer and biaxially oriented polyester films have been used. The body was used as a film for the writing surface (screen) of an electronic blackboard.

[Problem that the invention seeks to solve]

However, such writing sheets have poor writing properties.
For example, if you write on a whiteboard with a −-cur, it will bounce and you will not be able to get a clear screen. In addition, if you leave writing on the screen for a long time, it may not be able to be erased, or even if it can be erased, the erased residue will stick to the screen and the surface will become dirty. Especially when used as an electronic blackboard screen. However, the problem was that the stains were visible on the copied surface.

The present invention does not have the above-mentioned drawbacks, that is, it has good writability.

To provide a writing sheet with excellent erasability and from which erasing residue on the screen can be easily removed.

[Failure to solve the problem]

The present invention relates to a writing sheet comprising a protective layer on the writing side surface of a flexible sheet, the protective layer comprising a methyl-based silane coupling agent.

It consists of a reaction product mainly composed of an epoxy-based silane coupling agent and a curing agent, and is a mixture of the mixed amount (A) of the methyl-based silane coupling agent and the mixed amount (B) of the epoxy-based silane coupling agent. The ratio (A)/(B) is 5
It is a sheet-like article for writing characterized by having a ratio of /95 to 90/10.

What is the flexible sheet-like material referred to in the present invention?

These include organic plastic sheets (including films), paper, and laminates thereof. Organic plastic sheets are not particularly limited as long as they are molded from organic resins, but typical examples include polyesters such as polyethylene terephthalate and polycarbonate, polyolefins, polyamides, polyimides, polysulfones, polyetherimides, polyamideimides, and polyethersulfones. , polyphenylene sulfide, polyarylate.

Examples include fluororesins. Toughness.

A polyester sheet is preferred in terms of flatness, two-dimensional stability, adhesiveness, and the like. Among polyester sheets, polyethylene terephthalate C (hereinafter abbreviated as PET),
A biaxially stretched film (hereinafter the biaxially stretched film will be abbreviated as BO film) made of a copolymer having a PET component of 90 mol or more is preferred. The protective layer coating surface of the sheet material is subjected to discharge treatment, primer treatment, antistatic treatment,
It may also be one that has been subjected to matting treatment, flame retardant treatment, printing of 9 designs, 2 coloring, etc. Alternatively, additives such as a weathering agent, a coloring agent, a matting agent, an antistatic agent, and a flame retardant may be dispersed in a sheet-like material.

The thickness of the sheet-like material is 20 to 300μ, the tensile elastic modulus is 100 to 2000 d/m when measured with a Tensilon type tensile tester at a tensile speed of 200 mm/min, and the heat shrinkage rate is 2% or less when measured at 120 ° 0. Surface average roughness cutoff 2.5 m measured with a three-dimensional roughness meter (manufactured by Koita Research Institute)
m ) is preferably 0.8 μ or less. Flexibility and two-dimensional stability of sheet materials.

In terms of flatness and erasability, the thickness is 30 to 200μ, the tensile modulus is 200 to 1.000/wn, and the heat shrinkage rate is 1.
It is more preferable to set the average roughness of one surface to 0.4μ.

The methyl-based silane coupling agents applicable to the present invention are represented by the following general formulas (a) to e.

+(-CHs-(CH2),,S i(OR"),-ffl
C) 11 [However, m = 0 is still 1. n=an integer from 1 to 10.

R'-alkyl group having 1 to 10 carbon atoms, phenyl group.

Typical examples of methyl-based silane coupling agents include hydrocarbon residues selected from cyclohexyl groups, R″-carbonized groups selected from alkyl groups having 1 to 10 carbon atoms, and methyltrimethoxysilane, dimethyl Dimethoxysilane, methyltriethoxysilane.

Examples include dimethyljethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, and tolyltrimethoxysilane. In particular, from the viewpoint of erasability, the silane coupling agent of general formula (A) is preferred, and methyltrimethoxysilane is more preferably used.

The epoxy silane coupling agent is represented by the following general formula.

°Ku. H/L-“・　1′・ [However, m = O or 1. n=an integer from 1 to 10.

Fl' - alkyl group having 1 to 10 carbon atoms, phenyl group.

Hydrocarbon residue selected from cyclohexyl group, R'/=
A hydrocarbon residue selected from alkyl groups having 1 to 10 carbon atoms].

Typical examples of epoxy silane coupling agents include γ-glycidoxypropyltrimethoxysilane, γ
-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β (!1.4
-Epoxycyclohexyl)ethyltrimethoxysilane, etc.

In particular, silane coupling agents of the general formula) are preferred.

Further preference is given to using γ-glycidoxypropyltrimethoxysilane.

The mixing ratio of the amount of methyl silane coupling agent mixed (A) and the amount of epoxy silane coupling agent mixed (B) is (A)/(B) = 5/95 to 90/10 in weight ratio. ．． Preferably it is 20/80 to 70150, more preferably 30/70 to 60/40. If the mixing ratio of the silane coupling agent is less than 5/95, the erasability will be poor and the surface will be stained with residual shadows. Also, if it exceeds 90/10, the area written with a whiteboard marker will bounce off and you will not be able to draw clear lines or letters.

The curing agent used in the present invention may be any known curing agent that crosslinks by reacting with the epoxy group of the epoxy silane coupling agent.9 For example, aliphatic amine, aromatic amine, modified amine, acid anhydride, polyamide, Examples include melamine resin, phenol resin, and amino resin.

amine, diethylaminopropylamine 7, m-phenylenediamine, diaminodiphenylsulfone.

Dicyandiamide, boron trifluoride monoethylamine,
These include phthalic anhydride, hexahydrophthalic anhydride, and pyromellitic anhydride. It is also possible to use a mixture of two or more of these.

It is preferable to use aliphatic amines and aromatic amines in terms of easy removal of erasing residue, and aliphatic amines having 1 to 20 carbon atoms are preferable in terms of side-lighting properties. Typical examples include diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

The curing agent is preferably added in an equivalent amount to the epoxy group, and if it is too little, the performance of the protective layer will deteriorate.

The equivalent number of curing agents is calculated by a known method.2For example, in the case of an amine-based curing agent, active hydrogen is Blend the number of grams (1 gram amount) containing 1 piece.

The protective layer of the present invention is mainly composed of the composition described above, but various surfactants, inorganic particles, cationic monomers, oligomers, polymers, etc. may be dispersed and blended within the range that does not impair the purpose of the present invention. Good too.

In the present invention, the main reaction product means that the reaction product generated by the methyl silane coupling agent, epoxy silane coupling agent, and curing agent accounts for 60% by weight or more of the composition forming the protective layer. It is more preferable when the weight is 80 or more.

The reaction product of the present invention is a condensation reaction of silanol groups caused by hydrolysis of a methyl-based silane coupling agent and an epoxy-based silane coupling agent, and a crosslinking reaction between the epoxy group of the epoxy-based silane coupling agent and a curing agent. It is a good product, and the reaction rate of wrinkled lanol groups and epoxy groups is not particularly limited, but it is preferably 50 or more, more preferably 80 or more, and especially when the reaction rate is 90 or more, the erasability is remarkable. improves. The reaction rate of silanol groups is determined by quantifying the amount of silanol groups generated by hydrolysis of the silane coupling agent (C) and the amount of silanol groups remaining after condensation (D). The amount of epoxy groups (F) is calculated by quantifying the amount (F) of epoxy groups remaining after the reaction.

Furthermore, FT-IR (Fourier transform infrared spectrophotometer) is used to quantify these, and even in cases where measurement is difficult, measurements can be made.

The thickness of the protective layer is not particularly limited as long as it does not impair flexibility, but it is preferably 0.5 to 10μ.
In terms of durability and flexibility, it is more preferable to set the thickness to 2 to 5 μm.

Average surface roughness cutoff of protective layer surface 2.5nm+
) is 0.8μ or less, and from the viewpoint of erasability, it is more preferably 0.4μ or less.

The writing sheet used in the present invention is a known whiteboard (for example, Japanese Patent Application Laid-open No. 182795/1983).

Whiteboard described in Japanese Patent Application Laid-Open No. 60/25747)
A typical example is a sheet-like material used for an electronic blackboard screen, which is flexible enough to be easily written on and erased with a marker.

Next, the method for producing a writing sheet according to the present invention will be described with reference to an example in which a PET-EO film is used as the flexible sheet.

However, the present invention is not limited to these manufacturing methods.

(1) Add methyl-based silane coupling agent and epoxy-based silane coupling agent to water or methanol.

Hydrolysis is carried out by dissolving a predetermined amount in alcohols such as ethanol and isopropyl alcohol, aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, etc. Hydrolysis is carried out with pure water or acidic water containing an acid such as hydrochloric acid, sulfuric acid, acetic acid, or phosphoric acid. If the hydrolysis is exothermic, it is necessary to cool the solution.

This is usually carried out by adding acidic water all at once or gradually into the silane coupling agent solution.

The methyl-based silane coupling agent and the epoxy-based silane coupling agent may be mixed before or after hydrolysis.

A predetermined amount of curing agent is added to the silane coupling agent hydrolyzed mixture and stirred to form a coating solution.

The substrate to be coated may be subjected to corona discharge treatment in air or in various other atmospheres, if necessary.

Alternatively, the anchor treatment may be performed using a known anchor treatment agent such as urethane, acrylic, or epoxy.The coating on the base material is performed using a known method such as a graphiater, reverse coater, or bar coater. 60℃~
Dry at 250°C for about 1 second to 15 minutes. 20 to 180 as necessary to improve the toughness and adhesion of the coating film.
After-curing can be carried out at a temperature of 1 minute to 24 hours.

Although the present invention is characterized by the above-mentioned writing sheet, it can also be made into a writing sheet that can be used on both sides by providing a protective layer on both sides. By providing an antistatic layer on the other side of the object, it is possible to facilitate the removal of erase scum.

An electronic blackboard (for example, a housing described in Japanese Patent Application Laid-Open No. 59-215172, a writing medium fed out by a roller provided in the housing, and a writing medium provided at a predetermined position of the housing) Characters written with a writing instrument.

It consists of a sensor that converts figures, symbols, etc. into electrical signals, a device that supplies a recording medium, and a print head that prints and records on the recording medium according to the sensor's output.It converts the image of Sha9 characters from light into electrical signals. The sensor is placed in close contact with a writing surface, and the writing surface is made up of a plurality of rollers and an endless sheet hung between the rollers, and the writing surface is movable vertically or horizontally relative to the sensor. This includes an electronic whiteboard device characterized by having a structure that allows for. ) When used as a screen film, 5 to 20 weight of titanium oxide fine particles having an average particle diameter of 10 mμ to 3 μm are included in the sheet material for writing of the present invention.

[Effect]

The present invention is a reaction product obtained by mixing a specific silane coupling agent, especially a methyl-based silane coupling agent with excellent erasability, an epoxy-based silane coupling agent with excellent adhesiveness and durability, and a curing agent in a specific ratio. By forming a layer, the following excellent effects can be achieved.

〔Effect of the invention〕

(1) It does not flicker when written with a whiteboard marker and has good writing performance.

(2) It is easy to erase after writing, and it is especially easy to erase even if the writing is left for a long time.

(3) Erasing residue after erasing is small and removal is easy.

[Method of measuring characteristics, evaluation criteria]

The characteristics measurement method and evaluation criteria in the present invention are as follows.

(1) Writability 2 Commercially available whiteboard markers (
After writing with a Sakura white board marker WBK (manufactured by Sakura Crevasse ■) under a pressing load of 200 to 600 g, the repellency of the writing part was judged according to the following criteria.

◎: There is no repulsion at all.

○: Almost no repellency is observed.

△D In some parts, cracks are observed.

×: Significant repellency.

(2) Erasability 2 After writing in the same manner with the above marker, the markings were left under the following conditions and erased using a commercially available acrylic nonwoven fabric eraser.

(a) Immediate room temperature erasure ◎: There is no residual shadow and it is easy to erase.

O: There is almost no residual shadow, but it is difficult to erase it.

△: Some residual shadows are observed.

×: Significant residual shadow.

(3) Adhesion of erasing scum The evaluation was based on the complete absence of erasing scum remaining on the surface after writing and erasing at room temperature.

◎: Almost no erased residue is observed.

O: Some fine powder remains.

Δ: Significant adhesion of fine powder.

×: Significant adhesion of coarse powder.

(4) Flexibility After bending along a cylinder with a diameter of 5wn, the state of cracks on the surface was determined using a microscope.

◎: No cracks at all.

○: There are almost no cracks.

Δ: Innumerable cracks are observed.

×: Significant cracks appear.

〔Example〕

Hereinafter, embodiments of the present invention will be described based on Examples.

Examples 1 to 5 Methyltrimethoxysilane [Toray Silicone 5z6070 (manufactured by Toray Silicone)] was used as the methyl-based silane coupling agent, and γ-glycidoxypropyltrimethoxysilane [Toray Silicone] was used as the epoxy-based silane coupling agent. 5H6040 (manufactured by 1-Resilicone ■)] was used.

A 2[1wt% inglobiflorcol solution of each was prepared and hydrolyzed using N/10 hydrochloric acid as a catalyst.

This solution was mixed in the proportions shown in Examples 1 to 5 in Table 1, and triethylene teramine (hereinafter referred to as TETAJ) prepared with isopropyl alcohol to a concentration of 20 wt% was added.
) 10 parts by weight was added to 1 part by weight of N4N to 1 part by weight to prepare a coating liquid. PE with intrinsic viscosity (rv) 0.62 as coating substrate
T is biaxially stretched 3.3 times vertically and 3.5 times horizontally.

Heat-set thickness 75μ, tensile modulus 400-.

A PET-BO film with a heat shrinkage rate of 1% and a surface roughness of 0.01 μm was used, and the coated surface was subjected to corona discharge treatment in air to improve adhesion. A gravure roll was selected so that the coating thickness after drying with a gravure coater was 3μ±05μ, and the entire drying process was carried out for 165"C92 minutes to obtain a writing sheet having a protective layer.This writing sheet was All of them were flexible, had excellent write-once properties and erasability, and had little erasing residue attached to them.

Comparative Examples 1 to 2 Coated and dried in the same manner as in Example 1 using a 20 wt % isopropyl alcohol solution of SZ6070 hydrolyzate (Comparative Example 1).

and T for 100 parts by weight of 5H6040 hydrolyzate.
All samples were prepared by coating and drying in the same manner as in Example 1 using a 2Qwt% inpropyl alcohol solution containing 10 parts by weight of ETA (Comparative Example 2). After the writing sheet of Comparative Example 1 was written with a water-based marker, it flickered and the lines and characters became unclear. Also, part of the coating peeled off during erasing after a period of time, and erasing residue adhered to the screen after erasing, resulting in a significant stain on the screen.

The writing sheet of Comparative Example 2 was heated at high temperature (40°C) after writing.
), the erasability after being left for a long time (16 hours) at high temperature and high humidity (40°C, 100 RI ()) was almost impossible to erase.

Comparative Examples 3 to 4 Writing sheets were created in the same manner as in Example 3, except that 5Z6070'iγ-chloropropyltrimethoxysilane [Toray Silicone 5H6076 (manufactured by Toray Silicone ■)] in Example 6 was used. (Comparative Example 3).

Also, change 5H6040 in Example B to SH6[]76 and T
A writing sheet was prepared in the same manner as in Example 6 except that ITA was removed (Comparative Example 4).

All of these writing sheets had poor erasability and could not be put to practical use.

Example 6 In place of TETA-(i7 metaphenylenediamine) in Example B, 1
A writing sheet was prepared in the same manner as in Example 3 except that 0 parts by weight was added. This writing sheet has good writability,
It had excellent erasability and was flexible with less adhesion of erasing residue.

Comparative Examples 5 to 6 A hard vinyl chloride film with a thickness of 50 μm was bonded to a PET-BO film with a thickness of 75 μm using an all-urethane adhesive to create a writing sheet. (Comparative Example 5).

Also, instead of the hard vinyl chloride film, a 20μ ethylene-tetrafluoroethylene copolymer (copolymerization molar ratio 43
．． 57), (melting point 260°C, 650°C9, speed 10
A writing sheet was prepared in the same manner as in Comparative Example 5 using a film with a melt viscosity of 50,000 poise at 0 sec. The writing sheet of Comparative Example 5 had extremely poor erasability and had a lot of erasing residue attached. In addition, the sheet-like material for writing in Comparative Example B has poor writing properties, such as lines and letters.
Squeezing occurs when the image is crushed, resulting in blurred images, and large particles of eraser residue often adhere to the image after erasing.

Claims (1)

[Claims] A writing sheet comprising a protective layer on the writing side surface of a flexible sheet, the protective layer mainly containing a methyl-based silane coupling agent, an epoxy-based silane coupling agent, and a curing agent. reaction product, and the mixing ratio (A)/(B) of the mixed amount (A) of the methyl-based silane coupling agent and the mixed amount (B) of the epoxy-based silane coupling agent is 5/95 to 90. /10.