JPH06272196A - Substrate paper for releasing paper - Google Patents

Abstract

PURPOSE:To obtain a substrate paper for producing tackified products of excellent printing operability without curling or waving by coating the obverse face of a thick paper with a polyolefin resin composition and the reverse face with a specific resin composition. CONSTITUTION:The obverse face of a thick paper is coated with a polyolefin resin composition and the reverse face with a resin composition containing a mixture of a copolymer with a wax melting at 50 to 100 deg.C. The copolymer is prepared by emulsion polymerization of monomer components of (a) a mixture of hydrophobic alpha,beta-mono-ethylenic unsaturated monomer such as acrylic alkyl ester, methacrylic alkyl ester or a mixture thereof with an aromatic unsaturated monomer, (b) alpha,beta-unsaturated carboxylic acid and (c) other alpha,beta-monoethylenic comonomer bearing no cross-linkable group at a weight ratio of (a):(b):(c) of (30-90):(10-15):(0-60) and the amount of the wax is 2 to 40 pts.wt. per 100 pts.wt. of the total monomers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release paper base paper used for adhesive products such as adhesive paper and adhesive sheets, and more particularly to a release paper base paper having both sides of a base paper coated with a synthetic resin composition. Is.

[0002]

2. Description of the Related Art Adhesive papers and sheets are labels, stickers,
Printed on stickers, patches, tack forms, etc., it is used for a wide range of purposes such as commercial, industrial, office and household. These adhesive products generally have an adhesive sandwiched between a surface substrate and a release paper.

Paper, synthetic paper, laminated paper, film, foil, cloth and the like are used as the surface base material.

As release paper, base paper or substrate such as laminated paper, glassine paper, clay coated paper, resin coated paper, film, etc., coated on one or both sides with a polyolefin resin, silicone compound or fluorine compound, etc. It is formed by applying and processing the stripping agent on one side or both sides.
Among them, there is also a single-sided release agent-treated backside treated release paper in which a layer of synthetic resin or the like is provided on the backside of the base paper.

As the adhesive, a rubber type, an acrylic type, a vinyl ether type emulsion type, a solvent type,
Various adhesives such as hot melt type and radiation curable type are used. In many cases, an adhesive product is manufactured by a method in which a release agent is applied to a base paper and dried, an adhesive agent is further applied to the release agent application surface and dried, and then a surface base material is attached. In this case, the base paper shrinks after being coated and dried twice with the release agent and the adhesive, and the reactivity with respect to moisture and humidity is enhanced. Therefore, there is a drawback that the base paper tends to curl or wavy due to changes in humidity.

Further, as a special release agent, there is a radiation curable type such as EB or UV which does not require much heat when curing the release agent, but in these cases also, the base paper shrinks due to the coating and drying of the pressure-sensitive adhesive, so that moisture or moisture The reactivity with respect to humidity is enhanced, and when the humidity changes, curling or waviness tends to occur.

Therefore, a curl breaker is used to flatten the curled adhesive product on the surface opposite to the curling direction by using a curl breaker, or an air conditioner for adjusting the moisture content of the paper, steam damping, curling by water application, etc. There is also a method of straightening. However, in the case of a curl breaker, an air conditioner, and steam damping, the effect is insufficient and the process is inevitable. In addition, in the case of water application, there is a problem that the curl (water application curl) on the surface to which water is applied becomes stronger because it has a straightening effect but it is difficult to control the amount of water applied.

When a substrate having good dimensional stability against humidity changes such as films is used as the surface substrate,
It is common to use backside treated paper that has a layer of polyvinylidene chloride, polystyrene, styrene-butadiene copolymer, cellulose derivative, polyolefin resin, etc. on the backside of the release paper, but when the humidity change is still large In some cases, curling or waviness of the adhesive product may occur due to moisture absorption and desorption from the back surface or the side surface.

On the other hand, as a measure against curling and waviness, the base paper which serves as the base paper for the release paper has been improved, and a method of adding various chemicals at the time of making the base paper has been proposed. There are drawbacks such as efficiency and economical efficiency, and a method that is inexpensive and sufficiently satisfactory has not yet been established.

As described above, the curling and waviness of the adhesive product caused by the release paper are caused by printing, die cutting,
In the stage of processing labels, stickers, etc. through steps such as sheet cutting, paper feed failure, paper misalignment, printing misalignment, etc. occur. The quality problem of release paper is a serious obstacle to the quality of adhesive products, and the improvement of release paper is strongly desired.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to prevent curling or waviness of an adhesive product caused by a single-sided release paper.
Improved by using a base paper for release paper whose back surface is coated with a synthetic resin composition, which is inexpensive and has no curl or wavy,
Moreover, it is to provide a base paper for release paper for efficiently producing an adhesive product having excellent printing workability.

[0012]

DISCLOSURE OF THE INVENTION The present invention provides a base paper for a release paper in which both sides of a base paper are coated with a synthetic resin composition, one side of which is coated with a polyolefin resin composition and the other side of which is a monomer mixture consisting of: A release paper coated with a resin composition containing 2 to 40 parts by weight of a wax having a melting point of 50 to 100 ° C. as a main component and a wax having a melting point of 50 to 100 ° C. with respect to 100 parts by weight of all monomers. It is a base paper. Hydrophobic α / β-monoethylenically unsaturated monomer (hereinafter referred to as “hydrophobic monomer”) comprising at least one of acrylic acid alkyl ester, methacrylic acid alkyl ester or acrylic acid alkyl ester, methacrylic acid alkyl ester and unsaturated aromatic monomer. ) Is 30 to 90% by weight of all monomers. α · β-monoethylenically unsaturated carboxylic acid (hereinafter referred to as “unsaturated carboxylic acid”) is 10 to 10% of all monomers.
It is 15% by weight. Other α / β-monoethylenically unsaturated monomers having no crosslinkable functional group capable of copolymerizing with these (hereinafter referred to as “comonomer”) account for 60% by weight or less of all monomers.

[0013]

The present invention provides a base paper for release paper, which maintains the good performance of conventional release paper without curling or waviness due to humidity change and has an excellent printing workability. is there.

The present invention is particularly effective for an adhesive product using as a surface base material such as a film or a vapor-deposited paper having extremely low moisture absorption / desorption property. Further, an adhesive product using such a surface base material is required to have good smoothness on the silicone paper coated with release paper. Considering these points,
It is preferable that one side of the base paper for release paper is coated with the polyolefin resin composition.

The components of the above resin composition for coating the back surface of the base paper for release paper, which is a feature of the present invention, will be described in order. Typical examples of the hydrophobic monomer are, for example, butyl acrylate and acrylic acid-2-
Ethylhexyl, butyl methacrylate, methacrylic acid-
2-ethylhexyl, lauryl methacrylate, stearyl methacrylate, styrene, alkyl acrylates such as α-methylstyrene, alkyl methacrylate and unsaturated aromatic monomers, which are acrylic acid ester, methacrylic acid ester or acrylic acid ester, It is necessary that at least one of the methacrylic acid ester and the unsaturated aromatic monomer is present in the range of 30 to 90% by weight, more preferably 30 to 89% by weight, based on the total monomers of the resin component.

Typical examples of the unsaturated carboxylic acid include, for example, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, etc., and at least one of them is used as a total monomer of the resin component. To 10 to 15% by weight, more preferably 11 to 14% by weight.

Typical examples of the other α / β-monoethylenically unsaturated monomer which may be copolymerized with the hydrophobic monomer as the copolymer of are, for example, methyl acrylate, ethyl acrylate and methyl methacrylate. , Vinyl acetate, acrylonitrile, etc., and it is necessary that at least one of them is present in an amount of 60% by weight or less based on the total monomers of the resin component.

When the ratio of the above-mentioned hydrophobic monomer to all the monomers is less than 30% by weight, the water resistance of the formed film obtained is lowered and the effect of mixing with the wax is remarkably lowered.

When the ratio of the unsaturated carboxylic acid to all the monomers is less than 10% by weight, the stability of emulsion dispersion of the cobolomer obtained is hindered, and it is difficult to obtain a stable emulsion dispersion. On the other hand, when it exceeds 15% by weight, the formed film obtained tends to have poor water resistance, and further, the viscosity change due to the pH change of the emulsified dispersion liquid is significantly affected to deteriorate the coating workability.

If the ratio of the above-mentioned comonomer to all the monomers exceeds 60% by weight, the hydrophilicity of the resulting copolymer becomes too strong, the water resistance of the film formed is lowered, and the effect of mixing with the wax is reduced. Will not be recognized.

In addition, as a copolymer, a functional group-containing monomer that imparts crosslinkability by heat or an acidic catalyst, such as acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, or glycidyl. Acrylate, glycidyl methacrylate, β-hydroxyethyl acrylate,
It is also possible to copolymerize at least one kind of β-hydroxypropyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl methacrylate and the like in an amount of about 0.5 to 5% by weight. By copolymerizing such a functional group-containing monomer, the resulting copolymer is given thermosetting properties, and as a result, by subjecting it to a heat drying treatment that is usually carried out at the time of coating, the resulting coated product has a water resistance. Since it is imparted and durability is improved, excellent water resistance can be maintained for a long period of time.

The copolymer emulsion of the above-mentioned components constituting the composition of the present invention is prepared by using a water-soluble polymerization initiator in the presence of a surfactant and / or an oligomer having a surface-active property or a water-soluble polymer substance. It is carried out by an emulsion polymerization method in which the polymerization is performed. The surfactant is appropriately selected by combining at least one kind of anionic, nonionic or cationic surfactant.

The water-soluble polymerization initiator is also a polymerization initiator used in ordinary radical polymerization, for example, a persulfate such as ammonium persulfate, potassium persulfate or sodium persulfate, hydrogen peroxide, t-butyl. Inorganic or organic peroxides such as hydroperoxide can be used. In that case, a reducing substance, for example, sodium metabisulfite, sodium bisulfite, or sodium rongalitate is combined with the water-soluble polymerization initiator to form an emulsion by using a radical polymerization initiator system by oxidation-reduction reaction. A so-called redox polymerization method for carrying out polymerization can also be applied.

On the other hand, the melting point of the composition of the present invention is 5
The emulsion containing wax in the range of 0 to 100 ° C. includes paraffin wax, microcrystalline wax and intermediate product wax, and it is particularly important to use a mixture of paraffin and microcrystalline wax. These waxes are used as a mixture of one kind or two or more kinds, and these are mixed with an anionic surfactant and / or
Alternatively, it is used as a wax emulsion using a nonionic surfactant.

The mixing ratio of the above-mentioned copolymer and the above wax in the composition of the present invention is copolymer 1 based on the solid content ratio.
The amount of wax is 2 to 40 parts by weight, more preferably 5 to 30 parts by weight, based on 00 parts by weight. When the proportion of this wax is less than 2 parts by weight, the effect of water resistance is small. On the other hand, if the amount exceeds 40 parts by weight, the stability of the aqueous dispersion becomes unstable, and layer separation occurs during long-term storage,
In addition, the adhesiveness and adhesiveness of the coated substrate are also reduced, and it becomes difficult to maintain durability and water resistance.

The method of adding the wax emulsion includes a method of adding the wax emulsion after the production of the copolymer emulsion and a method of producing the copolymer emulsion in the presence of the wax emulsion. Good.

As a method for coating or impregnating the composition obtained as described above onto paper, a coater coating method such as a bar, rod, air knife, doctor knife, gravure roll, various rolls, curtain, spray or a size is applied. A commonly used method such as an impregnation method such as pressing can be applied.

Further, the release paper base paper of the present invention is further curled by setting the water immersion elongation of the base paper used to 0.5 to 3.0%, more preferably 0.5 to 2.5%. And wavy can be improved. At this time, if the water immersion elongation exceeds 3.0%, curling or waviness occurs due to moisture absorption and desorption from the back surface or side surfaces, while if it is less than 0.5%, it is difficult to manufacture the base paper. Because it is not realistic.

As a method for producing a base paper, for example, there is a method in which various chemicals are added at the time of making a base paper or a base paper made by a Fourdrinier paper machine, a twin wire paper machine, a Yankee paper machine or the like. As a chemical additive, a wet paper strength enhancer such as a fibrin reactive resin or a dimensional stabilizer may be used. The present invention is of course not limited to these, but contains 0.2 to 1.0% by weight of a higher fatty acid synthetic sizing agent as an internally added size of the papermaking raw material with respect to the absolutely dry pulp, and further has a surface size of It is preferable to size press the coating liquid containing starch as the main component in the range of 0.5 to 2.0 g / m ² in terms of solid content weight. For the size press coating liquid, for example,
Surface sizing agents, paper strength agents, other auxiliaries and the like can be added.

As the higher fatty acid-based synthetic sizing agent, for example, an alkali salt of a higher fatty acid, an anhydride, a methylol compound or the like can be appropriately selected and used. It is desirable to adjust the addition amount thereof in the range of 0.2 to 1.0% by weight, more preferably 0.3 to 0.8% by weight, based on the bone-dry pulp. If the addition amount is less than 0.2%, it is difficult to obtain the effect,
If it exceeds 1.0%, the interlaminar strength and surface strength of the base paper will decrease.

The surface of the coating solution containing starch as a main component is sized by a size press installed in the drying process of the paper machine. As the starch, for example, oxidized starch, cationized starch and the like can be appropriately selected, and the size press treatment amount is 0.5 to 2.0 g / m ^{2 in} solid content weight, and more preferably 0.8 to.
Adjust to a range of 1.5 g / m ² . If it is less than 0.5 g / m ² , the effect of improving the interlayer strength, surface strength and waist stiffness of the base paper is insufficient, and if it exceeds 2.0 g / m ² , curling and waviness are likely to occur.

The base paper for release paper thus obtained is
There is no curling or waviness due to changes in humidity, and adhesive products using this product have excellent printing workability and suitability for use.

[0033]

EXAMPLES Next, the present invention will be described in detail with reference to Examples, but all parts and% mean “parts by weight” and “% by weight” unless otherwise specified.

Example 1 100 parts of deionized water, 1.5 parts of sodium dodenylbenzel sulfonate, 3.5 parts of polyoxyethylene phenol ether and 0.5 part of ammonium persulfate were dissolved in a reaction vessel made of stainless steel, Then 5 parts of lauryl methacrylate, 65 parts of butyl acrylate, 9 parts of ethyl acrylate, 9 parts of methyl methacrylate and 12 parts of acrylic acid were added.
30 parts of a monomer phase mixed with 1 part was charged, the temperature was raised to 75 to 80 ° C. in a nitrogen stream to start the polymerization, and after 30 minutes, the remaining monomer phase was added dropwise at the same temperature for 180 minutes to complete the polymerization. Let Then, cool to 30 ° C., add 1.2 parts of 28% ammonia water and 5 parts of deionized water, and add pH.
Adjusted to 7.2. The copolymer emulsion (A-1) thus obtained had a solid content of 50.8% and a viscosity (Brookfield) at 25 ° C. of 350 cps.

Next, with respect to 100 parts of the solid content of this copolymer emulsion, 20 parts of a solid content of a wax emulsion having a solid content of 30% (trade name: Carbomul P-212, manufactured by Dik Hercules) is stirred at room temperature. While adding, a stable coating resin composition was obtained.

Next, this resin composition is
The back side of the 1.0% (elongation) base paper is coated using a Mayer bar coater, and a low density polyethylene resin (trade name: Mirason SP16, manufactured by Mitsui Petrochemical Co., Ltd.) has a thickness of 20 μm. As described above, lamination processing was performed with a T-die to prepare a base paper for release paper.

Toluene-based silicone release agent (trade name: KS770, manufactured by Shin-Etsu Chemical Co., Ltd.) is applied to the polyethylene surface of this base paper.
With a bar coater to apply a dry coat amount of 0.5 g / m ² ,
A release paper was obtained by drying with a hot air dryer. An acrylic emulsion paste (trade name: Nikasol L144, manufactured by Nippon Carbide Co., Ltd.) was applied to the release surface of the obtained release paper with a reverse roll coater at a solid content weight of 25 g / m ² and dried. Then, a pressure-sensitive adhesive sheet was obtained by using a polyester film as a surface base material to be bonded to the pressure-sensitive adhesive layer. In the production process of the release paper and the pressure-sensitive adhesive sheet, the release paper base paper could be efficiently produced without curling.

Example 2 5 parts of lauryl methacrylate, 65 parts of butyl acrylate,
The same procedure as in Example 1 was repeated except that the monomer mixture was changed to 9 parts of ethyl acrylate, 8 parts of methyl methacrylate, 12 parts of methacrylic acid and 1 part of glycidyl methacrylate, and the copolymer emulsion (A-
Example 1 except that 2) was obtained and this (A-2) was used.
A base paper, a release paper and an adhesive sheet were prepared in the same manner as in.

Example 3 The same procedure as in Example 1 was repeated except that the monomer mixture consisted of butyl acrylate (87 parts), N-methylolacrylamide (1 part) and acrylic acid (12 parts) was used. ), And (A-
Same as Example 1 except that 3) was used.

Example 4 A copolymer emulsion (A-4) was obtained by repeating the same procedure as in Example 1 except that the monomer mixture was changed to 70 parts of butyl acrylate, 18 parts of styrene and 12 parts of acrylic acid. Then, except that this (A-4) was used,
Same as Example 1.

Comparative Example 1 15 parts of lauryl methacrylate and 34 parts of ethyl acrylate
Parts, methyl methacrylate 39 parts and acrylic acid 12 parts, except that the monomer mixture was changed to the same operation as in Example 1 to obtain the copolymer emulsion (B
-1) was obtained and the same as in Example 1 except that this (B-1) was used.

Comparative Example 2 5 parts of lauryl methacrylate, 73 parts of butyl acrylate,
A copolymer emulsion (B-2) was obtained by repeating the same procedure as in Example 1 except that the monomer mixture was changed to 10 parts of ethyl acrylate, 10 parts of methyl methacrylate and 2 parts of acrylic acid. Same as Example 1 except that B-2) was used.

Comparative Example 3 Example 1 was repeated except that a base paper having a water immersion elongation of 3.5% was used.
Same as.

Comparative Example 4 Example 2 was repeated except that a base paper having a water immersion elongation of 3.5% was used.
Same as.

The pressure-sensitive adhesive sheet thus obtained was evaluated as follows. After printing on the surface base material with a glass printer, die cutting (punching) is performed to remove the surplus of the surface base material (70% of the surface base material), and then the sheet is taken out, and the temperature is 25 ° C, the humidity is 90% and the temperature is 20 ° C. After being left for one day in a printing room with a humidity of 30%, the curl and wavy state were evaluated and the results are shown in Table 2.

The curl is evaluated by a sheet (25 cm in the flow direction of the paper machine of the base paper and 1 in the width direction) of the sheet coming out of the glass press.
8 cm) and the straight length at both ends of the curl in the width direction was evaluated. The curled ones were marked with 16 cm or more, and marked with 16 cm or less. As for the waving, the undulating deformation was marked with X, and the flat shape without deformation was marked with ◯.

[0047]

[Table 1]

[0048]

[Table 2]

[0049]

As is clear from the results of the examples, the release paper base paper obtained by using the resin composition of the present invention and the base paper can efficiently obtain the release paper and the adhesive product with high quality. did it. The release paper using the release paper base paper of the present invention has solved the troubles that occur during the adhesive processing. Further, the adhesive product was inexpensive, had no curl or waviness, and was excellent in print workability and suitability for use.

Claims (2)

[Claims] 1. A base paper for release paper in which both sides of a base paper are coated with a synthetic resin composition, one side of which is coated with a polyolefin resin composition, and the back side of which is emulsion copolymerized with a monomer mixture consisting of the following as a main component. The resulting copolymer and wax having a melting point of 50 to 100 ° C.
A base paper for release paper, which is coated with a resin composition in an amount of 2 to 40 parts by weight with respect to parts by weight. Hydrophobic α / β-monoethylenically unsaturated monomer consisting of acrylic acid alkyl ester, methacrylic acid alkyl ester or acrylic acid alkyl ester, methacrylic acid alkyl ester and at least one kind of unsaturated aromatic monomer is 30 to 90% by weight of all monomers. %. The α / β-monoethylenically unsaturated carboxylic acid is 10 to 15% by weight of all monomers. The amount of the other .alpha..beta.-monoethylenically unsaturated monomer having no crosslinkable functional group capable of copolymerizing with these is 60% by weight or less based on the total amount of the monomers. 2. A base paper comprising a surface sizing composition containing 0.2 to 1.0% by weight of a higher fatty acid-based synthetic internally added sizing agent with respect to an absolute dry pulp and starch as a main component. The base paper for release paper according to claim 1, wherein the base paper contains 0 g / m ² and the water elongation of the base paper is 0.5 to 3.0%.