JPH0521070B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a release paper having a release layer that has excellent printing properties, particularly with water-based inks such as fountain pens, water-based pens, and printer inks, and has good release properties against adhesives. It is something.

Release paper, in which a release agent layer is formed on a paper base material, is widely used as a separator in pressure-sensitive labels, pressure-sensitive tapes, and the like. Note that in this specification, "paper" includes not only paper made of intertwined fibers in a narrow sense, but also synthetic paper, etc., as well as sheet or film materials whose essential purpose is writing or printing. shall be. As a release agent,
Polyorganosiloxanes, copolymers of acrylic esters, waxes, paraffins, etc. have been used or proposed, but the printability of the surface of the release layer, especially when using water-based inks, is still insufficient. . Therefore, when printing on release paper, treatment with a release agent that has both printing properties and release properties is essential, but there has been no release agent suitable for such uses.

Furthermore, the paper used as the base material for release paper that requires such printability is required to have good writing properties and the feel of normal paper, so it is better to use resin-coated paper or processed paper such as film laminated paper. However, it is preferable to use paper without seals, such as ordinary high-quality paper. However, with such unfilled paper, the release agent has a strong permeability into the base material, and conventional solvent or emulsion type release agents cannot provide a good release surface.

The main object of the present invention is to solve the above-mentioned problems, to have a coating cured layer of an ionizing radiation-curable release agent that can be applied without a solvent, and to have good releasability and good resistance to water-based inks. The purpose of this paper is to provide a release paper that has excellent printability.

The release paper of the present invention was developed to achieve the above-mentioned object, and more specifically, the release paper of the present invention has a polyorganosiloxane moiety in one molecule on a paper base material,
It is characterized by having a release layer consisting of a cured layer coated with an ionizing radiation-curable release agent having a polyether moiety and a free acrylic group.

The present invention will be explained in more detail below. In the following descriptions, "%" and "parts" indicate the composition.
are based on weight unless otherwise specified.

The ionizing radiation-curable release agent used in the present invention (hereinafter often simply referred to as "release agent") has a polyorganosiloxane moiety, a polyether moiety, and a free acrylic group in one molecule. This release agent can be obtained by using an organopolysiloxane having a polyether bond represented by the following general formula (1) as a starting material and introducing a free acrylic group thereto by a method as explained below.

However, here, R ¹ and R ² are each a methyl, ethyl, propyl or trifluoropropyl group, x and y are each a positive number; m is an integer of 0 to 4; n is an average value in the range of 2 to 3 .

In the organopolysiloxane represented by the above general formula (1), the releasability of the resulting release agent layer can be controlled by the degree of polymerization y of the organopolysiloxane moiety, and the releasability of the resulting release agent layer can be controlled in the range of 5 to 500, particularly 10 to 500. Preferably used. When the degree of polymerization y is less than 5, sufficient releasability cannot be obtained, and when it exceeds 500, printing suitability is slightly reduced. Also, the polyether part (C _o
H _2o O) _x has the most important influence on the printability of the resulting release agent layer, and if an alkylene oxide in which n is 4 or more is used, the desired printability cannot be obtained. n can be a mixture of 2 and 3, but its average value is also 2 to 3, preferably 2 to 3.
The range of 2.5 is particularly preferable in terms of providing good printing suitability for water-based inks. The degree of polymerization x of the polyether portion is determined in relation to the degree of polymerization of the organopolysiloxane portion, mainly so as to provide a good balance between the release properties and printing properties of the release agent layer obtained. In other words, when the value of y/x becomes large and the organopolysiloxane portion becomes relatively large,
The releasability increases but the printability deteriorates, and conversely, when the value of y/x decreases and the polyether portion decreases, the printability increases but the releasability deteriorates. Therefore, a range of 0.5 to 10 is appropriate for y/x.

On the other hand, the total degree of polymerization of organopolysiloxane is 2x
+y affects the reactivity with polyisocyanate. If 2x+y is too small, a large amount of polyisocyanate is required, which has such an effect that the releasability deteriorates. If 2x+y is too large, the degree of crosslinking of the release agent will decrease, resulting in a decrease in film strength or poor curing. Taking these points into consideration, x is selected from a range of 2 to 100.

The alkylene moiety C _n H _2n located between the organopolysiloxane moiety and the polyether moiety does not particularly need to exist, and in this case it has the advantage of being able to be produced at low cost. It has the advantage of increasing the stability of polysiloxane. However, organopolysiloxanes with m of 5 or more have no particular advantage in terms of performance, but are disadvantageous in terms of raw material availability, so m is 3.
or 4 is preferred, particularly 3 is most preferred. Specific examples of organopolysiloxanes include the following.

Although there is some degree of discretion in the method of introducing free acrylic groups into the organopolysiloxane (component (A)) represented by the above general formula (1), the first method is the above organopolysiloxane (component (A)). component
A method is used in which (A)) is reacted with (B) an organic polyisocyanate and (C) an acrylate compound having at least one active hydrogen-containing group such as a hydroxyl group, a carboxyl group, or an amino group in one molecule.

As the polyisocyanate (B), aliphatic and aromatic polyisocyanates having two or more isocyanate groups in the molecule are used, and specifically, tetramethylene diisocyanate, hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate,
4,4-diphenylmethane diisocyanate,
1,5-naphthalene diisocyanate, 3,3'-
Dimethyl 4,4'-diphenylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, trimethylhexamethylene diisocyanate, triphenylmethane triisocyanate, and etc. can be mentioned. These polyisocyanates may be used in combination.

Next, as the acrylate compound (component (A)) used in the present invention, one having at least one active hydrogen-containing group selected from a hydroxyl group, a carboxyl group, and an amide group in one molecule is used, Specifically, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, 4-hydroxycyclohexyl acrylate, 5-hydroxycyclooctyl acrylate, 5-hydroxycyclooctyl methacrylate, 2 -Hydroxy-3 phenyloxypropyl acrylate, etc., and adducts of acrylic acid, methacrylic acid, or 2-hydroxyethyl acrylate with phthalic anhydride; one active hydrogen group such as acrylamide, methacrylamide, N-methylolacrylamide, etc. Furthermore, addition reaction products of diepoxy compounds and acrylic acid such as ethylene glycol diglycidyl ether dimethacrylate, diethylene glycol diglycidyl ether dimethacrylate, propylene glycol glycidyl ether diacrylate, and phthalic acid diglycidyl ester diacrylate; Alternatively, a reaction product of glycidyl acrylate or glycidyl methacrylate and a dibasic acid may be mentioned. As a specific dibasic acid,
itaconic acid, maleic acid, fumaric acid, succinic acid,
Examples include adipic acid and terephthalic acid.

The above components (A), (B) and (C) are organopolysiloxane (component (A)) and acrylate compound (component
(C)) and the total amount of polyisocyanate (component
Within that range, more specifically, 1 of component (B) is used in a quantitative ratio that is approximately equal to the equivalent of (B)).
Component (C) is 0.01 to 0.7 equivalent, especially 0.4 equivalent
The range of ~0.7 equivalent is the peelability, printability, coating suitability,
This is preferable in terms of harmonizing curability, cured film properties, etc.

There is also some degree of discretion in the method of reacting the above three components.

In the first embodiment, an excess of organic polyisocyanate is reacted with organopolysiloxane to form a prepolymer having free isocyanate groups at both ends. At this time, the chain length of the prepolymer can be changed by changing the quantitative ratio of organopolysiloxane and polyisocyanate. Next, an acrylate compound is added to both ends of the prepolymer obtained above. In a second embodiment, an organic polyisocyanate and an acrylate compound are first reacted to produce a compound having a free isocyanate group at at least one end, and then further reacted with an organopolysiloxane.

In either embodiment, the above reactions proceed without a catalyst, but a catalyst can be used to accelerate the reaction. Such catalysts include dibutyltin dilaurate, stannous octoate, dioctyltin diacetate, morpholine, triethylenediamine, and the like. These catalysts can be used, for example, in a proportion of 0.01 to 1.0%, based on the total weight of the reaction mixture.

The second method for obtaining a release agent by introducing a free acrylic group is to prepare an organopolysiloxane (component (A)) represented by the above general formula (1), which has a group reactive with its hydroxyl group, as follows. This is a method of reacting with an acrylate compound (component (D)) classified into groups (a) to (c).

(a) Compounds having at least one carboxyl group in one molecule Specifically, acrylic acid, methacrylic acid, 2-
Adducts of hydroxyethyl methacrylate and phthalic anhydride; or reaction products of glycicyl acrylate or glycicyl methacrylate with dibasic acids such as itaconic acid, maleic acid, fumaric acid, succinic acid, acipic acid, and terephthalic acid. , etc.

(b) Acrylate compound having an ethyleneimine ring represented by the following general formula (2) (R ³ in the formula represents a hydrogen atom or an acrylic group having 1 to 4 carbon atoms, and k is an integer of 1 to 10.) Specifically, those represented by the following chemical formula are exemplified.

(c) Acrylate compound having an epoxy group represented by the following general formula (3) (R ⁴ in the formula is a hydrogen atom or has 1 to 4 carbon atoms.
(1 is an integer of 1 to 10) Specifically, glycicyl ester of acrylic acid or methacrylic acid can be mentioned.

The acrylate compound having a group reactive with the hydroxyl group described above (component (D)) is used in an approximately equivalent amount to the organopolysiloxane described above (component (A)).

The reaction conditions for both of the above components differ slightly depending on the type of reactive group in the acrylate compound (component (D)). Examples of typical methods are as follows.

b) In the case of carboxyl groups, the dehydration condensation reaction with the hydroxyl groups in the organopolysiloxane (component (A)) can be carried out using mineral acids such as sulfuric acid and hydrochloric acid, organic acids such as aromatic sulfonic acids, or borofluoride. A Lewis acid such as an etherate is used as a catalyst. Using a large excess of benzene and toluene as solvents, the water produced is separated by azeotropic distillation to allow the reaction to proceed.

b) In the case of the ethyleneimine ring, the ring-opening addition reaction with the hydroxyl group is performed using sulfuric acid, HBF ₄ ,
It is carried out in the presence of an acid catalyst such as HBF ₃ OR.

c) In the case of epoxy groups The ring-opening addition reaction with hydroxyl groups also proceeds by heating without a catalyst, but it is possible to accelerate the reaction by adding a catalyst. As the catalyst, an acid or a base is used, and usually inorganic bases and organic bases are mainly used. Examples of the inorganic base include potassium hydroxide and sodium hydroxide. Examples of the organic base include tertiary amines such as triethylamine and pyridine.

The release agent obtained as described above may be used alone, but if necessary, other reactive monomers,
It can be used in mixtures with solvents, pigments, fillers and other additives. As the reactive monomer, an acrylate monomer having an unsaturated bond or a vinyl or allyl group-containing monomer is used, for example, in an amount of about 5 to 100 parts per 100 parts of the release agent.

The release paper of the present invention is obtained by applying the above-mentioned release agent or release mixture onto a paper base material and curing it by irradiating it with ionizing radiation.

As the base material, various uncoated or coated papers such as rough paper, medium quality paper, high quality paper, gravure paper, cotton paper, art paper, coated paper, etc. are suitably used.

The appropriate amount of the release agent to be applied is 0.1 to 5 g/m ² (solid content). If the coating amount is less than 0.1 g/m ² , the unevenness on the surface of the substrate will not be completely flattened, and therefore sufficient releasability will not be obtained. Also
Even if it is applied in an amount exceeding 5 g/m ² , no further improvement in releasability can be expected and it becomes uneconomical. The coating method is basically arbitrary, and for example, methods such as roll coating, gravure coating, air knife coating, curtain flow coating, etc. are used. In terms of coating suitability, it is desirable that the viscosity at the time of coating be 10,000 centistokes or less, and if necessary, the viscosity can be adjusted by adjusting the molecular weight of the above reaction product or diluting it with a reactive monomer as appropriate. .

After applying the release agent as described above, the release paper of the present invention is obtained by irradiating and curing ionizing radiation such as electron beams, gamma rays, x-rays, and short wavelength ultraviolet rays. For example, electron beams are emitted from various types of electron beam accelerators such as Kotscroft-Walton type, Van de Graaff type, resonant transformer type, linear type, dynamitron type, and high frequency type, and are 50 to 1000 KeV.
Preferably, an electron beam with an energy in the range of 100 to 300 KeV is used. The radiation dose is 0.5
~10 Mrad is appropriate.

As described above, according to the present invention, by having a release layer formed by curing a release agent having a polyorganosiloxane part, a polyether part, and a free acrylic group in one molecule by irradiation with ionizing radiation, a good release layer can be obtained. A release paper is provided that has both releasability and good printability even with water-based inks.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Hydroxyethyl acrylate was added dropwise to a mixture of tolylene diisocyanate and 10% ethyl acetate while maintaining the temperature of the reaction system at 40 to 60°C. After the addition was completed, stirring was continued for 2 hours to obtain an adduct of tolylene diisocyanate and hydroxyethyl acrylate.

The adduct obtained above was added in equimolar amounts to the following organopolysiloxane having a polyether bond.

Di-n-butyltin dilaurate was added as a catalyst to this mixture in an amount of about 0.1% of the total amount, and stirring was continued for 3 hours while maintaining the mixture at 50 to 60°C to cause a reaction.

The release agent of the present invention obtained by adding 0.01% of hydroquinone to the reaction product obtained above was coated on high-quality paper (55 kg made by Daishowa Paper Industries) by roll coating in an amount of 0.5 g/m. ² , then apply an electron beam irradiation device (manufactured by ESI,
Using electro curtain CB200/50/30),
It was cured by irradiation with an electron beam under the conditions of an accelerating voltage of 175 KV and an irradiation dose of 1 Mrad. Furthermore, on the opposite side of the surface to which the above release agent was applied, apply acrylic adhesive (BPS2411 manufactured by Toyo Ink) in a striped manner in an amount of 10 g/
It was applied so that it was ² m2. After this, when printing was performed on the peeled surface using an ink containing a polyether binder as the main component, the print was clear and the peeling force against the adhesive (180° peeling, 30cm/min (pulling speed) is
A good result of 10g/cm was obtained. Further, although unwinding was performed at a pulling speed of 100 m/min, no damage to the base material such as paper unevenness occurred.

Example 2 While keeping a mixture of tolylene diisocyanate and its 10% vinegar and ethyl at 50 to 60°C, approximately 0.5 mole of silicone represented by the following formula was added to 1 mole of tolylene diisocyanate.
0.1% of the catalyst di-n-butyltin dilaurate was added dropwise.

After the dropwise addition, stirring was continued for 3 hours to obtain a prepolymer having isocyanate groups at both ends. Then, for 1 mole of the above prepolymer, 2
mol of hydroxyethyl acrylate,
Stirring was continued for 3 hours while maintaining the temperature at 50-60°C. 0.01 for the total amount of reaction products thus obtained.
% of hydroquinone was added.

When the obtained release agent was coated in the same manner as in Example 1 and the writability and releasability were evaluated, good results were obtained.

Example 3 0.1 per mole of organopolysiloxane represented by and organopolysiloxane as catalyst
% by weight of P-toluenesulfonic acid, plus 3% of the total amount
Two moles of acrylic acid was added to a mixture of twice the amount of toluene as a solvent, and the mixture was heated and stirred. Acrylated organopolysiloxane was obtained by continuing heating and stirring for 6 hours while separating the produced water by azeotropic distillation. Hydroquinone was added in an amount of 0.05% by weight to obtain a releasable treatment agent.

The above releasable treatment agent was applied to high-quality paper (Daishowa Paper Co., Ltd. 55).
Kg) is coated using a roll coating method at a coating amount of 0.5 g/ ^m2 , and then an electron beam irradiation device (manufactured by ESI/Electro Curtain CB200/
50/30), acceleration voltage 175KV, irradiation dose
It was cured by irradiating it with an electron beam under 3 Mrad conditions.
Furthermore, an acrylic pressure-sensitive adhesive (BPS2411 manufactured by Toyo Ink) was applied in stripes to the non-peelable surface in an amount of 10 g/m ² . After doing this, when we printed on the peeled surface using an ink containing a polyether binder as the main component, clear prints were obtained, and the peeling force against the adhesive (180° peeling, 300cm/min) was obtained. tensile speed) is 10g/cm
and obtained good results. In addition, although unwinding was performed at a pulling speed of 100 m/min, no damage to the base material such as paper flakes occurred.

Example 4 1 mol of the same organopolysiloxane as in Example 3, 0.01% by weight of sulfuric acid as a catalyst, and further 30% by weight of a solvent (methyl ethyl ketone) were added and mixed based on the organopolysiloxane. Set the liquid temperature to 70~
While keeping at 80℃ 2 mol of was added dropwise, and stirring was continued for an additional 5 hours after the addition to obtain an acrylated organopolysiloxane. Hydroquinone was added in an amount of 0.05% by weight to obtain a release agent.

The above releasable treatment agent was applied to high-quality paper (Daishowa Paper Co., Ltd. 55).
Kg) is coated using a roll coating method at a coating amount of 0.5 g/ ^m2 , and then an electron beam irradiation device (manufactured by ESI/Electro Curtain CB200/
50/30), acceleration voltage 175KV, irradiation dose
It was cured by irradiating it with an electron beam under 3 Mrad conditions.

Thereafter, in the same manner as in Example 3, application of an adhesive to the non-peelable surface, printing on the peelable surface, and rewinding tests were performed, and similarly good results were obtained in all cases.

Example 5 1 mol of the same organopolysiloxane as in Example 3, 1% by weight of pyridine as a catalyst, and 30% by weight of a solvent (methyl ethyl ketone) were added and mixed based on the weight of the organopolysiloxane. 2 mol of glycidyl methacrylate was added dropwise while maintaining the liquid temperature at 70 to 80°C, and after the addition, stirring was continued for an additional 5 hours to obtain a methacrylated organopolysiloxane. Hydroquinone was added in an amount of 0.05% by weight to obtain a releasable treatment agent. This releasable treatment agent was coated on high-quality paper (55 kg made by Daishowa Paper Industries) using a roll coating method to a coating amount of 0.5 g/m ² , and then an electron beam irradiation device (ESI
The material was cured by irradiating it with an electron beam using an electrocurtain (CB200/50/30) manufactured by Co., Ltd. at an accelerating voltage of 175 KV and an irradiation dose of 3 Mrad. Thereafter, in the same manner as in Example 3, application of an adhesive to the non-peelable surface, printing on the peelable surface, and rewinding tests were performed, and similarly good results were obtained in all cases.

Example 6 A release treatment agent and treated paper were obtained in the same manner as in Example 3, except that the same molar amount of organopolysiloxane represented by the following formula was used instead of the organopolysiloxane used in Example 3.

Thereafter, in the same manner as in Example 3, application of an adhesive to the non-peelable surface, printing on the peelable surface, and rewinding tests were performed, and similarly good results were obtained in all cases.

Claims (1)

[Claims] 1. A release layer consisting of a cured layer coated with an ionizing radiation-curable release agent having a polyorganosiloxane part, a polyether part and a free acrylic group in one molecule on a paper base material,
Printable release paper.