JPH08174994A - Ohp sheet for ink jet recording - Google Patents

Abstract

PURPOSE: To improve the printing characteristics, water resistance, preservation stability, blocking resistance, etc., by providing an ink receiving layer containing polyvinyl acetal resin, water-soluble acrylic resin and filler on a transparent base. CONSTITUTION: An ink jet recording OHP sheet comprises an ink receiving layer containing polyvinyl acetal resin. water-soluble acrylic resin and filler on a transparent base. Preferably, the weight ratio of the acetal resin to the acrylic resin is set to (9:1) to (3:7). As the filler, acrylic resin fine particles having mean particle size of 0.1 to 30μm are used. The acetal resin is synthesized by reacting aldehyde with polyvinyl alcohol and acetalizing it. As the polyvinyl alcohol to be the material of the acetal resin, its polymerization degree is 300 to 4500, preferably 500 to 4500.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an inkjet recording O.
HP sheet, especially transparency, printing characteristics, water resistance,
The present invention relates to an OHP sheet for inkjet recording, which has excellent storage stability and blocking resistance.

[0002]

2. Description of the Related Art The ink jet recording system is low in noise, capable of high-speed recording, multi-coloring, compact printer, and recording / printing on both special recording paper and plain paper. Therefore, it has been widely adopted in various recording and printing devices such as facsimiles, printers, and computer terminals, and occupies a field of important information devices that have been rapidly spreading in recent years.

On the other hand, in recent years, a method of directly recording and printing information from a computer on a so-called overhead projector (OHP) sheet has been put into practical use, and an ink jet recording method is also adopted as this recording method. The OHP sheet used in this system has a structure in which an ink receiving layer is formed on a light transmissive substrate.

This OHP sheet for ink jet recording (hereinafter sometimes simply referred to as "OHP sheet").
The following six items are examples of the characteristics required for the above.

High transparency. The absorption of ink into the ink receiving layer is rapid, there is no color stain such as yellow, magenta, cyan, and black, and the saturation is high and a clear color tone can be reproduced (printing characteristics, especially fixability). When performing multi-color recording by combining inks, each ink component is quickly absorbed even if ink dots overlap on the same surface of the recording sheet, and the recording surface does not become dirty even at high speed recording It has ink absorption speed and ink absorption capacity (printing characteristics).

It is water resistant and does not cause image bleeding or bleeding even if water adheres to it. OHP sheets are stacked in a paper feed case such as an inkjet printer, and the stacked sheets often cause blocking.
Do not cause blocking when stacking sheets (blocking resistance). No fading occurs even when the printed matter is stored (stability over time).

In order to satisfy these conditions,
For example, in JP-A-59-174381, OHP
It has been proposed to use a water-soluble resin such as polyvinyl alcohol or carboxymethyl cellulose for the ink receiving layer of the sheet. Further, JP-A-58-89391 proposes to crosslink the water-soluble resin in the ink receiving layer of the OHP sheet in order to improve water resistance.

[0008]

However, when a water-soluble resin such as polyvinyl alcohol or carboxymethyl cellulose is used in the ink receiving layer, the transparency of the entire OHP sheet and the printing characteristics of the ink are good, but the water resistance is poor. There is a problem that it will be enough. Further, when the water-soluble resin of the ink receiving layer is crosslinked, the water resistance becomes good, but there is a problem that the absorbability of the ink and the temporal stability after printing are deteriorated.

Furthermore, the transparency of the OHP sheet is lowered, and when the sheet is fed to the printer, the sheets may rub against each other and damage the ink receiving layer or the substrate, which is a problem in handling. It was

For these reasons, conventionally, no OHP sheet for ink jet recording has been provided which can satisfy all of the above properties (1) to (3).

The present invention has been made in view of the above conventional circumstances, and has transparency, printing characteristics, water resistance, storage stability,
OH for inkjet recording with excellent blocking resistance
The purpose is to provide a P sheet.

[0012]

The OHP sheet for ink jet recording according to the present invention is characterized in that an ink receiving layer containing a polyvinyl acetal resin, a water-soluble acrylic resin and a filler is provided on a light transmitting substrate.

The present invention will be described in detail below. The OHP sheet of the present invention is characterized in that an ink receiving layer containing a polyvinyl acetal resin, a water-soluble acrylic resin and a filler is provided on a light transmissive substrate.

The polyvinyl acetal resin is synthesized by reacting polyvinyl alcohol with an aldehyde to form an acetal. Alternatively, it can be synthesized by concurrently performing saponification and acetalization using polyvinyl acetate. The acetalization method includes dissolution method, precipitation method,
A conventionally known method such as a homogeneous method can be adopted.

The polyvinyl alcohol used as the raw material for the polyvinyl acetal resin generally has a degree of polymerization of 300 to
4,500, preferably 500-4500 are used. The higher the degree of polymerization of polyvinyl alcohol, the better the ink fixability and water resistance of the OHP sheet obtained. The saponification degree of polyvinyl alcohol is usually 8
It is 0.0 to 99.5 mol%.

On the other hand, examples of aldehydes used for the synthesis of polyvinyl acetal include aliphatic aldehydes and aromatic aldehydes. Of these, aliphatic aldehydes include formaldehyde, acetaldehyde, butyraldehyde, hexyl aldehyde, octyl aldehyde,
Decyl aldehyde and the like can be mentioned. Further, as the aromatic aldehyde, benzaldehydes having a substituent such as benzaldehyde, 2-methylbenzaldehyde, 3-methylbenzaldehyde, 4-methylbenzaldehyde, chlorobenzaldehyde, phenylacetaldehyde, and phenyl-substituted alkylaldehydes such as β-phenylpropionaldehyde. Examples thereof include those having a condensed aromatic ring such as compounds, naphthaldehyde and anthraldehyde, and those having a substituent such as a hydroxyl group, an alkoxy group, an amino group and a cyano group on the aromatic ring. Of these,
Aromatic aldehydes are preferably used because the resulting OHP sheet has good ink fixability, water resistance, and transparency.

The degree of acetalization of the polyvinyl acetal resin used in the present invention is preferably in the range of 2 to 40 mol%, more preferably 3 to 30 mol%, and particularly preferably 5 to 20 mol%. is there. If the degree of acetalization is too low, the resulting OHP sheet has good ink fixability but poor water resistance. Conversely, if the degree of acetalization is too high, water resistance is good but ink fixation The sex becomes worse.

Here, the degree of acetalization is expressed by the following formula, where A is the number of moles of acetal groups contained in the polyvinyl acetal resin, B is the number of moles of acetyl groups, and C is the number of moles of hydroxyl groups. Is the value to be set. {A / (A + B + C)} × 100 [mol%]

By using the polyvinyl acetal resin, it is possible to improve the printing characteristics without sacrificing other characteristics.

On the other hand, the OHP sheet of the present invention contains a water-soluble acrylic resin together with the polyvinyl acetal resin in the ink receiving layer. In the present invention, any water-soluble acrylic resin may be used as long as it is a resin or resin composition composed of a water-soluble acrylic acid ester polymer. Specifically, it is composed of a polymer of acrylic acid ester (polyacrylic acid ester) obtained by esterification reaction of acrylic acid or acrylic chloride with alcohols, transesterification reaction of methyl acrylate, and the like. The water-soluble acrylic resin is available as an aqueous solution or an aqueous emulsion, forms a water-resistant film after drying, and improves the adhesiveness between the translucent substrate and the ink receiving layer, resulting in good blocking resistance. To

In the ink receiving layer, the weight ratio of polyvinyl acetal resin to water-soluble acrylic resin is 9: 1 to.
The range of 3: 7 is preferable, and the range of 6: 4 to 4: 6 is more preferable. If the proportion of water-soluble acrylic resin is too high,
The ink absorbency of the ink receiving layer is lowered, and the ink dries slowly. On the other hand, if the amount of polyvinyl acetal is too much, the film strength of the ink will decrease. Thus, by mixing two specific resins in a specific ratio to form the ink receiving layer, an OHP sheet for inkjet recording having excellent printing characteristics, water resistance and adhesiveness can be obtained.

In the OHP sheet of the present invention, the ink receiving layer further contains a filler. As the filler, organic polymer fine particles, inorganic oxide fine particles and the like can be used. Specific examples of organic polymer particles include acrylic resin, styrene resin, urea-formaldehyde resin,
Examples of the fine particles of benzoguanamine resin, silicone resin, fluororesin and the like, and inorganic oxide fine particles include silica, talc, alumina and the like. Of these,
Organic polymer fine particles, particularly acrylic resin fine particles are preferable because the OHP sheet obtained has good transparency, suppression of blocking, and scratch resistance.

The particle size of such a filler is 0.1 to 30.
The range of μm is preferable, and the range of 3 to 30 μm is particularly preferable. If this particle size is too large, the roundness of the printed dots will deteriorate, and if it is too small, blocking of the OHP sheet will occur easily. The particle shape of the organic polymer fine particles is better as it is closer to a true sphere. That is, the closer the particle shape is to a spherical shape, the higher the transparency of the receiving layer and the less likely it is that a scratch will occur.

When the amount of the filler contained in the ink receiving layer of the OHP sheet for ink jet recording of the present invention is too large, blocking is less likely to occur, but the transparency of the OHP sheet is lowered, and conversely, when the amount is too small, the transparency is decreased. Although good, blocking is likely to occur. For this reason,
The amount of the filler added depends on the amount of resin 10 that forms the ink receiving layer.
It is preferably 1 to 20 parts by weight, more preferably 1 to 10 parts by weight, relative to 0 parts by weight.

Further, various additives may be added to the ink receiving layer within a range that does not impair the effects of the present invention. Examples of the additives include water-based ink adsorption capacity improving agents such as glycerin, polyethylene glycol, and surfactants, and ink weather resistance improving agents such as ultraviolet absorbers and pH adjusters.

The ink receiving layer has a dry film thickness of 3 to 20 μm.
The range of m is desirable, and the range of 5 to 15 μm is particularly preferable. If the film thickness is less than 3 μm, the organic polymer particles, which will be described later, may fall off and the amount of ink received may be reduced.
If it exceeds μm, it may cause an increase in drying time and curling of the sheet in the manufacturing process of the OHP sheet.

The OH for ink jet recording of the present invention
The light-transmitting substrate that constitutes the P sheet may be any one that has good light-transmitting properties, and any one can be used. For example, a resin film of polyester, celluloid, polyvinyl chloride or the like can be used.

The OHP sheet for ink jet recording of the present invention is a coating liquid containing a polyvinyl acetal resin, a water-soluble acrylic resin, a filler, and other additives added as necessary on the surface of such a light-transmitting substrate. Can be easily produced by coating the composition with a bar coater method, a roll coater method, a blade coater method or the like and then drying it to form an ink receiving layer.

Examples of the ink jet ink used for the OHP sheet of the present invention include conventional inks containing a water-soluble dye, a wetting agent, a dye solubilizing agent, water and a water-miscible organic solvent.

[0030]

By forming the ink receiving layer of the OHP sheet for ink jet recording from a polyvinyl acetal resin, a water-soluble acrylic resin and a filler, the OH has excellent transparency, water resistance, ink absorbability and storage stability.
A P sheet is obtained. Further, the blocking property can be improved without impairing the scratch resistance, transparency, and stability over time.

[0031]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples below.

Example 1 To 240 g of polyvinyl alcohol having a degree of polymerization of 1600 and a degree of saponification of 90 mol%, 2 kg of water was added and heated, and when the polyvinyl alcohol was dissolved, the liquid was cooled and 35% by weight of hydrochloric acid was added.
20 g and 50 g of phenylacetaldehyde were added, and it was made to react at 10 degreeC for 5 hours. The degree of acetalization of the polyvinyl phenyl acetoacetal resin thus synthesized was 15 mol%.

58.8 parts by weight of a liquid obtained by dissolving this resin in a mixed solvent of water: isopropyl alcohol = 1: 1 (polyvinylphenylacetoacetal resin solid content conversion value).
And a solution of polyacrylic ester resin (trade name: Julimer AT-613, manufactured by Nippon Pure Chemical Co., Ltd., solid content 25
%, Aqueous solution) 39.2 parts by weight (the weight ratio of polyvinyl phenyl acetal resin and polyacrylic ester resin is 6: 4). To this mixed solution, 2.0 parts by weight of acrylic resin fine particles (trade name “BR89” manufactured by Mitsubishi Rayon Co., Ltd., central particle size 20 μm) was added as a filler to carry out a dissolution operation, and then a valve homogenizer (APV).
Gaulin INC. Made) pressure 200kg / cm
^The dispersion operation was performed in ² to prepare a coating material. This paint was applied onto a polyethylene terephthalate film (“T600” manufactured by Dia foil Co., Ltd., whose surface was corona-treated) with a bar coater to prepare an OHP sheet for inkjet recording having an ink receiving layer having a dry film thickness of 12 μm. did.

The produced OHP sheet was evaluated according to the following evaluation methods, and the results are shown in Table 1. For recording on the OHP sheet, a color inkjet printer "560C" manufactured by Hewlett Packard was used.

(I) Transparency The transparency of the OHP sheet before printing was measured using a transmitted light absorption measuring device (Macbeth TR927).

(Ii) Printing characteristics Printing was performed on the OHP sheet with an ink jet printer, and the printed dots were observed with a microscope. Even when the printing dots were circular and four colors of ink were overlaid and recorded, the ink did not flow out and the image was clear, and the image was judged as ◯, the one with bleeding was evaluated as Δ, and the others were evaluated as ×.

(Iii) Water resistance A OHP sheet was printed with an ink jet printer, the sheet 1 hour after printing was soaked in tap water for 1 minute and then the state of the ink image immediately after being pulled up was observed, and the water was dried. When the ink was allowed to return to its original state, it was evaluated as ◯, when the ink was partially eluted and the ink receiving layer swelled, as Δ, and when the ink receiving layer flowed away as ×.

(Iv) Blocking resistance Two OHP sheets are stacked with the ink receiving layer facing downward,
A weight of 100 g (the contact area with the OHP sheet was 5 cm ² ) was placed thereon, and the plate was allowed to stand for 20 days under the temperature and humidity conditions of 60 ° C. and 90% RH. Then, the sticking of the sheets was observed. When the sheet surface was stuck, it was judged as ×, and when sticking could not be confirmed, it was judged as ○.

(V) Adhesiveness Ink receiving layer of OHP sheet JIS K540
A cross-cut peeling test was performed by a method based on 0, and the number of blocks in which the receptive layer peeled off in 100 blocks was measured. The smaller the number of peeled blocks, the higher the blocking resistance.

(Vi) Storage stability: Four-color printing was performed on an OHP sheet with an ink jet printer, and the dot density after printing was measured using a Macbeth TR927 measuring instrument to measure the change over time in dot density immediately after printing and after 30 days. did. Of the four colors that showed the largest drop in dot density after 30 days,
The dot density of each color was set to 100, and the change amount relative to this was displayed in%. However, print quality evaluation items with x are not evaluated because measurement is impossible.

Example 2 A sheet was prepared in the same manner as in Example 1 except that butyraldehyde was used as the aldehyde in the synthesis of the polyvinyl acetal resin, and the same evaluation was performed.
It was shown to.

Example 3 A sheet was prepared in the same manner as in Example 1 except that the weight ratio of the polyvinyl acetal resin to the polyacrylic acid ester resin was 4: 6, and the same evaluation was performed. The results are shown in Table 1. .

Example 4 A sheet was prepared in the same manner as in Example 1 except that the weight ratio of the polyvinyl acetal resin to the polyacrylic acid ester resin was 9: 1, and the same evaluation was performed. The results are shown in Table 1. .

Example 5 A sheet was prepared in the same manner as in Example 1 except that the weight ratio of the polyvinyl acetal resin to the polyacrylic acid ester resin was set to 2: 8, and the same evaluation was performed. The results are shown in Table 1. .

Example 6 A sheet was prepared in the same manner as in Example 1 except that silica particles were used as the filler, and the same evaluation was performed. The results are shown in Table 1.

Comparative Example 1 Instead of polyvinyl phenyl acetoacetal resin, polyvinyl alcohol (trade name: Gohsenol GH17,
A sheet was prepared in the same manner as in Example 1 except that Nippon Synthetic Chemical Industry Co., Ltd. was used, and the same evaluation was performed. The results are shown in Table 1.

Comparative Example 2 A sheet was prepared in the same manner as in Example 1 except that polyethylene oxide (trade name: PE03, manufactured by Sumitomo Seika Chemicals Co., Ltd.) was used in place of the polyvinyl phenyl acetoacetal resin, and was the same. The results are shown in Table 1.

Comparative Example 3 A solution prepared by dissolving a polyvinyl acetal resin in a mixed solution of water: isopropyl alcohol = 1: 1 and adjusting the solid content to 10% without adding a polyacrylic acid ester, the solid content was 10%.
A sheet as in Example 1 except that 2.0 parts by weight of acrylic resin fine particles (trade name “BR89” manufactured by Mitsubishi Rayon Co., Ltd., central particle size 20 μm) were added as filler to 0 parts by weight equivalent. Was prepared and evaluated in the same manner, and the results are shown in Table 1.

Comparative Example 4 Polyvinyl phenyl acetoacetal resin was not used, and 100 parts by weight of an aqueous solution of polyacrylic ester resin was used as a filler, and acrylic resin fine particles (trade name "BR89" manufactured by Mitsubishi Rayon Co., Ltd., central particle size 20 μm) 2 A sheet was prepared in the same manner as in Example 1 except that 0.0 part by weight was added,
The same evaluation was performed and the results are shown in Table 1.

[0050]

[Table 1]

[0051]

As described in detail above, the OHP sheet for inkjet recording of the present invention is
By forming the ink receiving layer of the HP sheet from a polyvinyl acetal resin, a water-soluble acrylic resin and a filler, the transparency, water resistance and ink absorbency are excellent,
An OHP sheet having good storage stability can be obtained.

Claims (3)

[Claims] 1. An OHP sheet for ink jet recording, comprising an ink receiving layer containing a polyvinyl acetal resin, a water-soluble acrylic resin and a filler provided on a light transmissive substrate. 2. The OHP sheet for inkjet recording according to claim 1, wherein the weight ratio of the polyvinyl acetal resin and the water-soluble acrylic resin is 9: 1 to 3: 7. 3. The OHP sheet for inkjet recording according to claim 1, wherein the filler is acrylic resin fine particles having an average particle diameter of 0.1 to 30 μm.