JPS60155452A - Printable release paper - 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 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 those made of intertwined fibers in a narrow sense, but also synthetic papers, etc., as well as sheet or film-like materials for writing or printing purposes. shall be. As the release agent, polyorganosiloxane, acrylic ester copolymer, wax, paraffin, etc. are used.
Or, although it has been proposed, the printability of the surface of the release layer still remains
Printability is particularly poor when using water-based ink.

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 (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 and to have a coating cured layer of a radiation-curable release agent that can be coated without a solvent.
The object of the present invention is to provide a release paper that has both good releasability and good printability even with water-based inks.

The release paper of the present invention was developed to achieve two objectives, and more specifically, the release paper of the present invention contains the following components (a) to
A printable release paper characterized by having a release layer made of a cured product of a radiation-curable organopolysiloxane composition comprising (c).

(a) - In the molecule, the general formula (R1 in the formula represents a hydrogen group or a methyl group, R2 represents a substituted or unsubstituted monovalent hydrocarbon group, or represents an alkylene group or a -CO.〇- group) , n is a positive number less than or equal to 4,
p is a positive number, m is O or a positive integer, a is O1 or 2
100 parts by weight of an organopolysiloxane having at least one siloxane unit represented by the general formula (where R3 is an alkylene group and R4 is a substituted or unsubstituted monovalent hydrocarbon) mercaptoalkyl group-containing organopolysiloxane having at least two siloxane units represented by 0, b is 0, l or 2)
．． 1 to 50 parts by weight, and (c) photosensitizer 0 to 10 parts by weight.

The present invention will be explained in more detail below. In the following description, "%" and "part" expressing quantitative ratios are based on weight unless otherwise specified.

The siloxane (a) constituting the radiation-curable release agent (hereinafter often simply referred to as "release agent") used in the present invention has at least one siloxane unit represented by the above general formula (1>), and has at least one siloxane unit represented by the above general formula (1>). The meaning of the group is also as mentioned above, but to add a little bit, specific examples of R2 include methyl group,
Included are alkyl groups such as ethyl and propyl groups, aryl groups such as phenyl, aralkyl groups such as benzyl, and alkaryl groups such as xylene. Further, R2 may be any halogenated hydrocarbon group such as a chloromethyl group, a chloropropyl group, or a dichlorophenyl group. X is
It shows an ester bond of a methylene group, an ethylene group, a propylene group, a butylene group, etc.
In nO)p, when n is larger than 4, the lipophilicity becomes excessive and the hydrophilicity becomes poor. The value of n is in the range of 4 or less, and may be not only a constant value but also a mixture of n=2 and n=3, for example. Further, the value of p is in the range of 1-1000, particularly preferably in the range of 10 to 300. If the polyether portion is small, the wood-philicity will be low, the contribution of siloxane bonds will be large, and the water repellency will be strong.

Siloxane (a) has at least one siloxane unit represented by general formula (1), but has the following formula (3):
In combination with the siloxane unit represented by formula (1), it is preferable that 1 to 50 mol % of the total siloxane units be the siloxane unit represented by formula (1).

R'CS i Ot<-cv2・”・(3) (However,
RIl is the same or different group selected from the same group as R2, and C is a siloxane unit represented by a number of 0<c<4.

Specific examples of siloxane (a) include the following. In the following formula, Me is a methyl group, φ
represents a phenyl group, respectively -(OC2H4) @
CH2CH=CI(21-OCCH=CH.

Me 10000C=CH2 The group R3 in the siloxane unit represented by formula (2) of siloxane (b) represents a divalent hydrocarbon group, and specific examples thereof include a methylene group, an ethylene group, propylene group,
It also includes alkylene groups such as butylene groups, arylene groups such as phenylene groups, alkaline groups such as phenylethylene groups, and groups in which the hydrogen atoms in these groups are substituted with halogen atoms, etc. R4 is a monovalent hydrocarbon Examples include alkyl groups such as methyl group and ethyl group, alkenyl groups such as vinyl group or allyl group, aryl group, alkaryl group, etc., and hydrogen atoms of these groups are substituted with halogen atoms, etc. The following groups are exemplified.

Siloxane (b) has at least one siloxane unit represented by the above formula (2), and in combination with the siloxane unit represented by the following formula (4), the siloxane (b) has a siloxane unit of 50 to 100, which is the median of all siloxanes.
The number of molecules Ij, whose mol% is preferably siloxane units represented by formula (2), is not particularly limited, but when used without a solvent, it is preferably about 500 to 3000.

RlcSio, 4-c)7□...(4) Here, R'
, c have the same meaning as in equation (3).

Specific examples of siloxane (b) include those listed below.

Me Me Me Me Note that these siloxanes (a) and (b) are not particularly limited in their molecular structures, and may be linear, branched, or cyclic.

The release agent used in the present invention is to
0.1 to 50 parts, preferably 5 to 20 parts. If the amount of siloxane (b) is less than 0.1 part, the curability will be insufficient, and if it is added in excess of 50 parts, the releasability and writability will deteriorate.

The siloxane constituting the release agent may be composed entirely of the above-mentioned siloxanes (a) and (b), but in addition to these, for example, up to about 99 mol% of other siloxane components may be added to the siloxane (a). It can also be included. Such other siloxane components include 1, for example, a compound represented by the general formula % (5) (where R6 is the same or different group selected from the same group as R2, and d is a number such that O<d<4). Specifically, heptanoorganosiloxanes such as monomethylsiloxane, monophenylsiloxane, or monovinylsiloxane, diorganosiloxanes such as dimethylsiloxane, diphenylsiloxane, divinylsiloxane, or methylvinylsiloxane, trimethylsiloxane, Triorganosiloxanes such as dimethylvinylsiloxane and the like can be mentioned.

Furthermore, as the photosensitizer (component (c)) in the present invention, various conventionally known ones can be used, and specifically, acetophenone, flobiophenone,
Benzophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, 4
- Contains an organosilicon group which is disclosed in Japanese Patent Publication No. 48794/1983 as having excellent compatibility with chlorobenzophenone, 4,4'-1-dimethoxybenzophenone, benzfuran, benzoin, benzoin isopropyl ether, and organopolysiloxane. These photosensitizers (c), exemplified by benzophenone derivatives, are siloxanes (i) when the release agent is UV-curable.
It is desirable to add 0.5 parts or more per 100 parts, but it can be omitted when curable with ionizing radiation such as electron beams, but in any case, adding more than 10 parts will cause peeling. It should be avoided as it reduces the storage stability of the agent.

If necessary, it is also possible to add an antioxidant such as hydroquinone as a pot life extender to the release agent, and the amount added is preferably 50 to 11,000 pp. Depending on the purpose of use, conventional diorganopolysiloxanes, fillers, colorants, and other embellishing agents may be added to the extent that the characteristics are not impaired.

The stripping agent is obtained by mixing each of the above components, and its viscosity (mainly determined by the viscosity of the siloxane) is preferably about 10,000 cSt or less, considering workability when used as a solvent-free stripping agent. However, depending on the application, siloxanes ranging from low viscosity to high viscosity (including solids at room temperature) can be used.If siloxane has a high viscosity, it can be dispersed or dissolved in an organic solvent, It can be used after dilution.

If necessary, the acrylate monomer having an unsaturated bond can be used as a mixture with other reactive monomers, pigments, fillers, and other additives. , vinyl or allyl group-containing monomer, for example 5 to 100 parts per 100 parts of release agent.
It is used up to a certain extent.

The release paper of the present invention can be 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 such as ultraviolet rays or electron beams.

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, lightweight coated paper, and polyethylene laminated paper are preferably used. It will be done.

The appropriate amount of the release agent to be applied is 0.1 to 5 g/m' (solid content). If the coating amount is less than 0.1 g/m2, the unevenness on the surface of the substrate will not be completely flattened, and therefore sufficient releasability will not be obtained. Also 5 g/m
Even if more than 2 coatings are applied, 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 during 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. I do.

After applying the release agent as described above, for example 1
．． It is easily and quickly cured to provide a release layer by irradiation with ultraviolet light for 0 seconds or less or electron beam or other ionizing radiation of less than IOM Rad, particularly 5 M Rad or less. Examples of UV sources include xenon lamps, low pressure
Medium-pressure or high-pressure mercury, etc. can be used, and various electron beam accelerators such as bump graph type, synchronized transformer type, linear type, dynamidron type, and high frequency type can be used as the electron beam source.
An electron beam emitted from the electron beam having an energy in the range of 50 to 1000 KeV, preferably 1<10 to 300 keV is used. More specifically, as a source of ultraviolet light,
For example, the output per unit length is 80 to 160 W/c
m, the dominant wavelength is approximately 365 nm, and the wavelength range is 230 to 450 nm.
The irradiation time is generally several seconds or less, but a short time is preferable in order to avoid being affected by heat, and a time of 1 second or less is particularly preferable, that is, an electric power of 160W The irradiation time should be 1 second or less per 1 cm of lamp, and the electron beam can be irradiated with a spot beam at high speed or a continuous curtain-shaped beam from a linear filament, and the irradiation dose is is selected from the range o, 1 to 10 MRad.

As described above, according to the present invention, by having a release layer formed by curing a release agent containing an organopolysiloxane having a polyether moiety and an organopolysiloxane containing a mercapto group by irradiation with radiation, good release can be achieved. To provide a release paper that has both good printing properties and good printability even with water-based inks.

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

W! '' For a series of surganobolisiloxanes represented by the general formula and different in n and m, mercaptopropyl group-containing siloxanes (viscosity 50 cp, 25°C) each end-capped with trimethylsilyl groups were combined to give a total maximum of about It was added at a ratio of lθ%.

Each of the series of mixtures described in Section 2 was applied to high-quality paper (55 kg manufactured by Daishowa Paper Industries) by a roll coating method.
Coating was carried out to a concentration of 5 g/m2, and then an electron beam irradiation device was used, manufactured by CESI, Electro Curtain CB2.
00150/30), and was irradiated with an electron beam and cured under the conditions of an acceleration voltage of 175 KV and an irradiation dose of I M r a d. Furthermore, on the side opposite to the side where the release agent was applied, an acrylic adhesive (BPS2 manufactured by Toyo Ink) was applied in stripes.
411) was applied in an amount of 1Og/m'.

After doing this, we printed on the peeled surface using a printer using an ink containing a polyether binder as the main component, and it was possible to print clearly, and it was also easy to write with oil-based pens, water-based pens, etc. there were. Furthermore, the peeling force against the adhesive (180° peeling, pulling speed of 30 cm/min) was 10 g/cm, which was a good result.

The evaluation results of printing characteristics and releasability of the above series of release agents are summarized in the following table.

However, in the compositions of Examples 1 to 5 in the following table, the ratio of polyether-modified silicone (organopolysiloxane of the above general formula) to mercapto group-containing polyorganosiloxane is 93 nia only in Example 5. Other than that,
Both ratios are 90:10.

The evaluation criteria for printing characteristics and peelability shown in the table above are as follows.

0: Slight ink repellency is observed only in the writing test using a water-based pen.

■=No ink repellency was observed in the writing test with water-based pens and oil-based pens.

Acrylic solvent type adhesive (BP manufactured by Toyo Ink Co., Ltd.)
S-5127) peel force (1806 peel) is 100
g/5 cm or less.

A release agent obtained by adding 5 parts of benzophenone to 100 parts of each of the compositions of Examples 1 to 5 was coated on high-quality paper by a roll coating method in a coating amount. 0.4g/m
2, then output 80
It was cured by irradiating ultraviolet rays from a distance of locm using a W/cm high pressure mercury lamp. Furthermore, an acrylic pressure-sensitive adhesive (Toyo Ink BPS2411) was applied in stripes to the surface opposite to the surface to which the release agent was applied, in an amount of 10 g, 7 m@2. After doing this, clear writing was possible on the peeled surface using a water-based pen or a fountain pen. Furthermore, the peeling force against the adhesive is 10 g/
Good results were obtained with cm.

Claims (1)

[Claims] A printable release layer comprising a cured product of a radiation-curable organopolysiloxane composition comprising the following components (a) to (c) on a paper base material. paper. (a) - In the molecule, the general formula (in the formula, R1 represents a hydrogen group or a methyl group, R2 represents a substituted or unsubstituted monovalent hydrocarbon group, or represents an alkylene group or a -CO.〇- group) , n is 4
The following positive numbers, p is a positive number, m is 0 or a positive integer, a is 0
．． 1 or 2) 100 parts by weight of an organopolysiloxane having at least one siloxane unit represented by the general formula (where Rao is an alkylene group and R4 is a substituted or unsubstituted 1 mercaptoalkyl group-containing organopolysiloxane having at least two siloxane units (representing a valent hydrocarbon group, b is 0.1 or 2)
0.1-50 parts by weight. and (c) 0 to 10 parts by weight of a photosensitizer.