JPH06199034A - Recording sheet - Google Patents

Abstract

PURPOSE:To make quick absorption of ink drops possible while preventing blots and blurs by a method wherein a recording sheet suitable for recording with an ink jet printer is formed of two hydrated alumina porous layers in specific thickness having specific average pore radiuses that are different from each other. CONSTITUTION:In the recording sheet described herein, a hydrated alumina porous layer that has avergae pore radius of 30-80 angstrom and is made of boehmitesol in 100-160nm radius of secondary aggregated particles is layered in thickness of 5-40mum over a base that is made of plastic or paper. A hydrated alumina porous layer that has average pore radius of 50-100 angstrom and is made of boehmitesol in 300-500nm radius of secondary aggregated particles is layered in thickness of 1-20mum further thereon. Pore volume in the hydrated alumina porous layer is set as 0.3-1.0cc/g, and boehmitesol whose boehmite primary particle is in thickness of 60-100 angstrom on both sides of a crystal is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording sheet, particularly a recording sheet suitable for recording with an ink jet printer.

[0002]

2. Description of the Related Art In recent years, an overhead projector (hereinafter referred to as an OHP) has been increasingly used in place of a conventional slide projector for presentations at various academic conferences and conferences. In addition, transparent color printing is required for applications such as posters and packaging. Since printing and printing of these transparent sheets have no absorbency in the sheet itself as a base material, special consideration is required in terms of printing speed and drying as compared with printing performed on a general paper surface.

In order to obtain a very small amount of printed matter such as OHP sheets, a method of editing an original with a personal computer or a word processor and printing with a printer is widely used, and full-color printing is easy for the printer. Therefore, the inkjet method is attracting attention because of its low printing noise.

OHP sheets for ink jet printers are required to have both transparency and ink absorbability. The inventor of the present invention has disclosed in JP-A-2-276670.
JP-A No. 2003-242242 proposes a recording sheet which has both transparency and ink absorbability and is suitable as a recording material for an inkjet printer.

[0005]

In the ink jet system, ink droplets are ejected from a nozzle toward a recording material at a high speed, and in order to prevent clogging of the nozzle, a large amount of ink is used for the ink. Is included. To obtain high color density, it is necessary to use a large amount of ink,
The recording material is required to absorb ink quickly and to have a high absorptivity having an excellent color forming property.

In the ink jet system, one droplet ejected from a nozzle forms one dot of an image. If the ink is not absorbed promptly, the phenomenon of beading, in which droplets are joined to each other on the surface of the recording material to distort the dots, or the droplets come into contact with the sheet transfer means or the like and the image is blurred, Or there is a risk of bleeding.

The present invention provides a recording sheet capable of quickly absorbing ink droplets when they come into contact with each other to obtain an image without dot joining or blurring or blurring. To aim.

[0008]

SUMMARY OF THE INVENTION The present invention provides two
Secondary agglomerated particle diameter of the secondary agglomerated particle diameter is 5 to 40 μm, with an alumina hydrate porous layer having a mean pore radius of 30 to 80 Å formed from boehmite sol having a secondary agglomerated particle diameter of 100 to 160 nm. The present invention provides a recording sheet having an alumina hydrate porous layer having an average pore radius of 50 to 100Å formed from boehmite sol having a thickness of 300 to 500 nm and a thickness of 1 to 20 μm.

The recording sheet of the present invention has an alumina hydrate porous layer having an average pore radius of 30 to 80Å on a substrate. In this specification, this alumina hydrate porous layer is hereinafter referred to as a lower layer. When the average pore radius of the lower layer is 30 Å or less, it is not suitable because the dye in the ink does not have sufficient adsorbability. When the average pore radius of the lower layer exceeds 80Å, the transparency of the alumina hydrate porous layer is impaired, the color density of the recorded matter decreases, and when the base material is transparent, the transparency of the recording sheet is reduced. It is also unsuitable because it impairs sex. Here, the average pore diameter is based on the nitrogen desorption method.

The lower layer has a secondary agglomerated particle diameter of 100 to 16
It must be formed from 0 nm boehmite sol. The diameter of the secondary agglomerated particles of boehmite sol is 1
When it is less than 00 nm, the ink absorbency of the lower layer and the adsorbability of the dye in the ink are not sufficient, which is unsuitable. If the diameter of the secondary aggregated particles of the boehmite sol exceeds 160 nm, the transparency of the lower layer decreases, which is not preferable.

The boehmite sol is a colloidal solution in which boehmite (AlOOH) crystal particles are dispersed as sol particles. In the boehmite sol, primary particles may aggregate to form secondary particles. In the present invention, the boehmite sol thus formed with secondary agglomerated particles is used. The secondary agglomerated particle diameter is the size of the secondary particles measured by a laser method. Particle size measurement by the laser method is based on the principle that particles in a liquid that is in Brownian motion are irradiated with He-Ne laser light, light is scattered by Rayleigh scattering, and Doppler shift is caused by particle motion. It is by law.

The thickness of the lower layer is 5 to 40 μm. If the thickness of this layer is less than 5 μm, the ink absorbency and the amount of dye adsorbed in the ink are insufficient, which is not suitable. If the thickness of this layer exceeds 40 μm, the transparency of the recording sheet may be impaired and the mechanical strength of the lower layer may be reduced, which is not suitable.

In the recording sheet of the present invention, an alumina hydrate porous layer having an average pore radius of 50 to 100Å is provided on the lower layer. In this specification, this layer is hereinafter referred to as an upper layer. When the ink adheres to the recording sheet, the upper layer absorbs the ink rapidly and functions to prevent beading, ink blurring, and the like.

When the average pore radius of the upper layer is 50 Å or less, the ink absorption rate is not sufficiently high, which is not suitable.
If the average pore radius exceeds 100Å, the transparency of the upper layer will be impaired, the color density of the recorded matter will decrease, and if the substrate is transparent, the transparency of the recording sheet will also be impaired, which is unsuitable. .

The upper layer has a secondary agglomerated particle diameter of 300 to 50.
It must be formed from 0 nm boehmite sol. The diameter of secondary agglomerated particles of boehmite sol is 3
When the thickness is less than 00 nm, the ink absorption speed of the upper layer is not sufficient, which is unsuitable. If the diameter of the secondary aggregated particles of the boehmite sol exceeds 500 nm, the transparency of the upper layer is lowered, which is not preferable.

The thickness of the upper layer must be 1 to 20 μm. When the thickness of the upper layer is less than 1 μm, the effect of the present invention is not exhibited and the ink absorption speed is not sufficiently increased. When the thickness of the upper layer is more than 20 μm, the effect of increasing the absorption speed of the ink is not further increased, the transparency of the recording sheet may be impaired, and the mechanical strength of the upper layer may be decreased, which is not suitable. Is.

Further, the alumina hydrate porous layer preferably has a pore volume of 0.3 to 1.0 cc / g in both the upper and lower layers. When the pore volume is less than 0.3 cc / g,
It is not preferable because the ink absorbency may become insufficient. If the pore volume exceeds 1.0 cc / g, the transparency of the alumina hydrate porous layer may be impaired, which is not preferable.

In the present invention, the pore characteristics of the alumina hydrate layer change depending on the size and shape of the colloidal particles of boehmite sol. The pore characteristics depend not only on the secondary particles but also on the primary particles, and in the case of primary particles composed of large boehmite crystals, a porous layer having a large average pore radius can be obtained. In the recording sheet of the present invention, the boehmite primary particles have a crystal thickness of 60 to 60 in the (020) plane direction.
It is preferably 100Å. If the thickness is less than 60Å, the pore radius of the porous layer becomes small, and the ink absorbability and the dye adsorbability in the ink may be insufficient, which is not preferable. On the contrary, this thickness is 10
If it exceeds 0Å, the transparency of the porous layer may be impaired, which is not preferable.

The thickness of the boehmite crystal grains in the (020) plane direction is determined by the Scherrer's equation (t = 0.9) from the diffraction angle 2θ of the peak of the (020) plane of the powder X-ray diffraction analysis and the half value width B.
λ / Bcos θ). In this equation, λ is the wavelength of X-rays.

When a binder is used to impart mechanical strength to the porous layer, the pore characteristics also change depending on the kind and amount of the binder. Generally, the larger the amount of binder, the smaller the average pore radius.

In the present invention, various base materials may be used regardless of whether they are transparent or opaque. In the present invention, the base material is not particularly limited, and various materials can be used. Specifically, various plastics or papers such as polyester resins such as polyethylene terephthalate, polycarbonate resins, fluorine resins such as ETFE can be preferably used. Further, corona discharge treatment or undercoating may be performed for the purpose of increasing the adhesive strength or the like of the alumina hydrate porous layer.

Means for providing the alumina hydrate porous layer on the base material include, for example, a boehmite sol to which a binder is added to form a slurry, and a roll coater, an air knife coater, a blade coater, a rod coater, a bar coater, a comma coater, etc. It is possible to employ a method of applying and drying. By this method, the lower layer is first provided on the substrate, and preferably, after the binder is sufficiently cured, the upper layer is similarly provided.

[0023]

Since the recording sheet of the present invention is provided with a layer having a high ink absorption rate as the upper layer, when printing is performed with an ink jet printer, for example, when ink is ejected as droplets from a nozzle, It becomes possible to absorb the droplets ejected before the liquid reaches the recording sheet, and high quality recording without beading can be achieved.

[0024]

[Example] Crystal thickness of (020) plane direction synthesized by hydrolytic peptization method of aluminum isopropoxide 78Å, 2
Next, 100 parts by weight of the boehmite sol having a diameter of 145 nm of the next agglomerated particles was mixed with 11 parts by weight of polyvinyl alcohol (both in terms of solid content) and ion-exchanged water to prepare a coating liquid having a solid content of 15% by weight. This coating solution was applied to a polyethylene terephthalate film (thickness 125 μm) using a bar coater so that the thickness when dried was 35 μm, and dried.

Furthermore, 100 parts by weight of boehmite sol having a crystal thickness in the (020) plane direction of 80 Å and a secondary agglomerated particle diameter of 390 nm synthesized by hydrolytic peptization of aluminum isopropoxide, and 11 parts by weight of polyvinyl alcohol (In terms of solid content) and ion-exchanged water were mixed to prepare a coating liquid having a solid content of 10% by weight. This coating liquid was applied onto the above coating layer using a bar coater so that the thickness when dried was 5 μm, and dried.

As a result, the average pore radius on the substrate is 50Å
Of the alumina hydrate porous layer of 35 μm, and further 5 μm of the alumina hydrate porous layer having an average pore radius of 60Å.
A recording sheet having m layers laminated was obtained. This average pore radius was determined by measuring the coating layer obtained by coating and drying the upper layer coating liquid and the lower layer coating liquid on the substrate individually by the nitrogen desorption method.

A solid test pattern was printed on the above-mentioned recording sheet using an inkjet printer (manufactured by Canon Inc .; Pixel Pro). Immediately after printing, even if the printed portion was rubbed with a finger, no ink adhered. Further, when the portion of the pattern where the ink amount was large was observed, dot joining, bleeding, and blurring were not observed.

[0028]

The recording sheet of the present invention has high absorptivity, and when recording with an ink jet printer,
Since the ink droplets ejected from the nozzles can absorb the ink droplets immediately when they come into contact with each other, it is possible to perform high-quality recording without dot distortion, blurring, or blurring. Besides the ink jet printer, it can be suitably used for a recording system with a large amount of ink. Furthermore, when a transparent base material is used in this recording sheet, a recording sheet having high transparency can be obtained, so that it can be suitably used for applications such as an OHP sheet. Further, even when the base material is opaque, high quality printed matter can be obtained.

Claims (4)

[Claims] 1. A secondary aggregate particle diameter of 100 to 1 on a substrate.
An alumina hydrate porous layer having an average pore radius of 30 to 80 Å formed from a boehmite sol of 60 nm has a thickness of 5 to 40 μm.
m with a secondary agglomerated particle diameter of 300
˜500 nm boehmite sol having an average pore radius of 50 to 100 Å
A recording sheet having a thickness of 20 μm. 2. The pore volume of the alumina hydrate porous layer is:
The recording sheet according to claim 1, having a content of 0.3 to 1.0 cc / g. 3. The recording sheet according to claim 1, wherein the boehmite primary particles in the boehmite sol have a crystal thickness in the (020) plane direction of 60 to 100Å. 4. The recording sheet according to claim 1, which is used for recording with an inkjet printer.