JP2000027097A - Backside treating agent using aqueous emulsion for release paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a backside treating agent for releasing paper exhibiting good solvent resistance, blocking resistance and heat resistance when coated on paper, film or cloth. SOLUTION: This backside treating agent is obtained by including an aqueous emulsive composition having two-layer structure obtained by polymerizing at least one kind of aqueous vinyl-based monomer component II including 50-100 wt.% (meth)acrylamide in the presence of seed emulsion I of which seeds are a copolymer including 10-50 wt.% (meth)acrylonitrile based on the total copolymerizable monomers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous emulsion which can be applied to paper, film, cloth and the like to obtain excellent solvent resistance, blocking resistance and heat resistance. For example, a primer for release paper, a back surface treatment agent,
The coated surface such as a binder of a diazo photosensitive paper and a binder for an offset master can be used for applications requiring solvent resistance, blocking resistance, and heat resistance. In particular, when used as an undercoating agent when preparing a release paper, an excellent release coating liquid sealing effect can be obtained when a solvent-type release agent is applied thereon.

[0002]

2. Description of the Related Art Conventionally, as a release agent component used in release paper, silicone dissolved in a solvent has been used. This silicone is expensive, and it is necessary to obtain sufficient release performance with the smallest possible coating amount. Therefore, in general, silicone is applied after performing a filling treatment with an undercoat layer so that the silicone does not seep into the paper.

As such an undercoat layer, clay coating, coating of an aqueous polymer such as polyvinyl alcohol or starch, or lamination of polyethylene is used (US Pat. No. 3,403,045). issue). Recently, a resin emulsion such as an acrylate copolymer emulsion has been applied (Japanese Patent Publication No. 63-54035).

[0004] Although clay coating has heat resistance, it has poor adhesion to silicone, and aqueous polymers such as polyvinyl alcohol and starch have a brittle coating film and poor water resistance.
When stored only in the undercoat layer such as when the humidity is high, blocking is easy. Further, a laminate obtained by laminating polyethylene or the like has characteristics such as smoothness and flexibility, but is inferior in heat resistance.

[0005] Furthermore, resin emulsions are excellent in film-forming properties, but inferior in heat resistance and solvent resistance, and lack a sealing effect. Also, a method of mixing oxidized starch with a resin emulsion for the purpose of improving heat resistance and solvent resistance (Japanese Patent Application Laid-Open No. Sho 60-2)
No. 45683). Further, in the preparation of an image carrier for transfer, there is a method in which a paper is treated with a release agent and a binder emulsion composed of acrylonitrile-butadiene rubber is applied (US Pat. No. 3,933,503).

[0006]

As described above, at present, the coating resin compositions used so far do not always satisfy all the properties. The present invention overcomes the above-mentioned drawbacks of the prior art, and provides a back surface treatment agent for release paper using an aqueous emulsion composition that provides excellent solvent resistance, blocking resistance, heat resistance, and the like.

[0007]

Means for Solving the Problems The present inventors have found that film forming properties,
In a resin emulsion having excellent solvent resistance, an aqueous vinyl-based monomer, particularly (meth) acrylamide, is further obtained by polymerizing a solvent resistance and a blocking resistance,
As a result of finding an aqueous emulsion having excellent heat resistance and further intensive studies, the present invention has been completed.

That is, the present invention is to polymerize at least one aqueous vinyl monomer component (II) in the presence of a seed emulsion (I) containing 10 to 50% by weight of (meth) acrylonitrile in a comonomer. And a method for producing an aqueous emulsion, characterized in that a copolymer emulsion having a two-layer structure is obtained.

Further, the present invention relates to a method of polymerizing at least one aqueous vinyl monomer component (II) in the presence of a seed emulsion (I) containing 10 to 50% by weight of (meth) acrylonitrile in a comonomer. The present invention provides an aqueous emulsion composition having a two-layer structure.

Further, the present invention provides a back paper treating agent for release paper using the above-mentioned aqueous emulsion composition.

The seed emulsion (I) used in the present invention
As a resin emulsion obtained by copolymerizing (meth) acrylonitrile. (Meth) acrylonitrile is present in the comonomer in an amount of 10 to 50% by weight, preferably 20 to 5% by weight.
0% by weight. If the content of (meth) acrylonitrile is less than 10% by weight, the solvent resistance of the coating film will be poor, and if it exceeds 50% by weight, the stability of polymerization will be poor.

When polymerizing the seed emulsion, the radical polymerizable monomers copolymerizable with (meth) acrylonitrile include methyl acrylate, ethyl acrylate,
Acrylic esters such as propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, dodecyl acrylate, stearyl acrylate; methacrylic acid Methyl acrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-methacrylate
Methacrylates such as -butyl, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, dodecyl methacrylate, stearyl methacrylate; aromatic vinyl compounds such as styrene, α-methylstyrene and vinyltoluene; acrylic acid, methacrylic Ethylenically unsaturated carboxylic acids such as acids, crotonic acid, itaconic acid, maleic acid, fumaric acid; acrylic acid 2
-Hydroxyethyl, 2-hydroxyethyl methacrylate, acrylamide, methacrylamide, N-methylolacrylamide, N-methylolmethacrylamide,
Hydrophilic monomers such as N-butoxymethylacrylamide, glycidyl acrylate and glycidyl methacrylate; conjugated diolefins such as butadiene, isoprene and chloroprene; vinyl acetate, vinyl chloride, and vinylidene chloride.

A known emulsion polymerization method can be used for the polymerization method of the seed emulsion, and is not particularly limited. The glass transition temperature of the seed emulsion obtained at this time is in the range of −30 to 50 ° C., and more preferably −2 to 50 ° C.
The thing of 0-30 ° C is good. If the glass transition temperature is lower than -20 ° C, the formed film tends to cause blocking, and if it exceeds 50 ° C, the film forming property is poor and the film is brittle.

Next, the aqueous vinyl monomer component (II) to be polymerized in the presence of the seed emulsion (I) is a vinyl monomer which produces an aqueous polymer by polymerization. For example, as an aqueous vinyl monomer component (II),
(Meth) acrylamide in monomer component (II), 50-
Use 100% by weight. Preferably 70 to 100% by weight
It is. 50% by weight of (meth) acrylamide
If it is less than 30, sufficient solvent resistance, heat resistance and blocking resistance cannot be obtained, and polymerization may not proceed stably.

In the present invention, another aqueous vinyl monomer component (II) copolymerizable with (meth) acrylamide
Examples thereof include nonionic vinyl monomers such as diacetone acrylamide, N-methylol acrylamide, N-methylol methacrylamide, and vinylpyrrolidone; acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic acid ester, fumaric acid Anionic vinyl monomers such as acids; dimethylaminoethyl methacrylate;
There are cationic vinyl monomers such as trimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and triethylaminoethyl methacrylate,
These can be used alone or in combination of two or more. In addition to those exemplified here, any vinyl-based monomer that produces an aqueous polymer can be used in the present invention.

When the aqueous vinyl monomer used in the present invention is polymerized in a seed emulsion to produce the composition according to the present invention, the film formed from the obtained composition has a solvent resistance, As long as the blocking properties and heat resistance are not impaired, it is needless to say that the aqueous vinyl-based monomer can be copolymerized with the aqueous vinyl-based monomer using the hydrophobic vinyl-based monomer used in the seed emulsion capable of copolymerizing with the aqueous vinyl-based simple substance. . These are used as one kind or a mixture of two or more kinds.

In the present invention, when the aqueous vinyl monomer component (II) is polymerized in the presence of the seed emulsion (I) to produce an aqueous emulsion having a two-layer structure, the seed emulsion (I) and the aqueous vinyl The solid content ratio of the system monomer component (II) is (50:50) to (95: 5).
It is. Preferably it is (60:40)-(90:10). At this time, if the ratio of the aqueous vinyl monomer component (II) exceeds 50% by weight, the resulting film has poor water resistance, and tends to block when the humidity is high. Conversely, if it is less than 5% by weight, sufficient solvent resistance and heat resistance cannot be obtained.

The method of polymerizing the aqueous vinyl monomer component (II) in the presence of the seed emulsion (I) is to prepare the seed emulsion (I) in advance, prepare it, and then prepare the aqueous vinyl monomer. Polymerization is carried out by adding, or a seed emulsion is produced, and an aqueous vinyl monomer is continuously added to carry out polymerization.

The method of adding the aqueous vinyl monomer component can be simultaneous, continuous or divided dropping. In this case, it may be selected in consideration of polymerization stability, control of polymerization heat, etc.
It does not affect the performance of the resulting aqueous emulsion.

As the polymerization initiator, radical polymerization is carried out using only a peroxide such as potassium persulfate, ammonium persulfate or hydrogen peroxide, or the above-mentioned peroxide and sodium acid sulfite or sodium thiosulfate are used. Redox polymerization can be carried out in combination with such a reducing agent. The amount of the radical polymerization initiator to be used is suitably from 0.1% to 20% by weight relative to the aqueous vinyl monomer. More preferably, it is 0.1% to 10%.

The reaction temperature varies depending on the type of the monomer to be used, the type of the polymerization initiator, and the like.
A temperature range of 0 ° C. is appropriate. In addition, if necessary,
It is also possible to add a chain transfer agent such as mercaptans.

The particle size of the aqueous emulsion of the present invention is 0.1.
It is suitably from 0.5 to 0.6 μm. More preferably, 0.
1 to 0.4 μm is good.

Further, according to the production method of the present invention, a stable aqueous emulsion can be produced without using a surfactant which is usually used when conducting emulsion polymerization. Of course, a surfactant may be used if necessary.

In such an aqueous emulsion, an aqueous polymer such as celluloses, starch and polyvinyl alcohol, a crosslinking agent such as a melamine resin, a formaldehyde resin and an aqueous epoxy resin, and a filler may be used as long as the desired effects of the present invention are not impaired. , An antifoaming agent, a wetting agent, a leveling agent, a film-forming auxiliary, and the like can be appropriately added.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The aqueous emulsion composition thus obtained can be directly applied to paper, film, cloth or the like, or an inorganic pigment such as calcium carbonate, clay, titanium oxide or a plastic pigment. When mixed with an organic pigment, such an aqueous emulsion composition is used as a binder for the pigment and applied to paper or the like, a film having excellent solvent resistance, blocking resistance, and heat resistance can be obtained.

For example, a primer for a release paper, a back surface treatment agent,
Diazo photosensitive paper binder, coated surface such as offset master binder solvent resistance, blocking resistance,
Useful for applications requiring heat resistance. In particular, when preparing a release paper, an excellent sealant effect of a release agent coating liquid can be obtained as an undercoating agent for applying a solvent-type release agent. Further, it is also useful as a back surface treatment agent for release paper requiring blocking resistance and heat resistance.

When used as a binder for diazo photosensitive paper and a binder for offset master, it has good miscibility with inorganic pigments and the like, and a stable pigment coating solution can be obtained.
When formed into a film, an excellent solvent-resistant film is obtained.

[0028]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto. Hereinafter, in Examples and Comparative Examples, parts are parts by weight unless otherwise specified.

Example 1 1110 deionized water was placed in a separable flask equipped with a thermometer, a reflux condenser, a stirrer, and a monomer charger.
Parts, 1 part of sodium dodecylbenzenesulfonate,
After purging with nitrogen gas, the temperature was raised to 70 ° C. After adding 10 parts of potassium persulfate, 300 parts of acrylonitrile, 680 parts of n-butyl acrylate, and 20 parts of methacrylic acid were emulsified with 400 parts of deionized water and 1 part of sodium dodecylbenzenesulfonate for 3 hours continuously. Into the flask. Thereafter, the mixture was further reacted at the same temperature for 3 hours, and neutralized to pH 7 with aqueous ammonia to obtain a seed emulsion. To 800 parts of this seed emulsion, 38 parts of acrylamide, 2 parts of acrylic acid and 20 parts of deionized water are added, and the mixture is heated to 40 ° C., followed by 20 parts of a 10% by weight aqueous solution of ammonium persulfate and 20 parts of a 10% by weight aqueous solution of sodium acid sulfite. And a polymerization reaction was carried out for 1.5 hours. Thereafter, the pH was adjusted to 7 with aqueous ammonia to obtain an aqueous emulsion composition. Table 2 shows the evaluation results.

Example 2 A seed emulsion was obtained by repeating the same operation as in Example 1 except that the composition was as shown in Table 1. To 800 parts of the seed emulsion, 80 parts of methacrylamide and 40 parts of deionized water are added, and the mixture is heated to 40 ° C., and then 40 parts of a 10% by weight aqueous solution of ammonium persulfate and 40 parts of a 10% by weight aqueous solution of sodium acid sulfite are added. The polymerization reaction was performed for 1.5 hours. Thereafter, the pH was adjusted to 7 with aqueous ammonia to obtain an aqueous emulsion composition. Table 2 shows the evaluation results.

Example 3 A seed emulsion was obtained by repeating the same operation as in Example 1 except that the composition was as shown in Table 1. To 450 parts of this seed emulsion, 114 parts of methacrylamide, 6 parts of acrylic acid and 310 parts of deionized water were added, and the mixture was heated at 40 ° C.
Then, 60 parts of a 10% by weight aqueous solution of ammonium persulfate and 60 parts of a 10% by weight aqueous solution of sodium acid sulfite were added, and a polymerization reaction was performed for 3 hours. Thereafter, the pH was adjusted to 7 with aqueous ammonia to obtain an aqueous emulsion composition. Table 2 shows the evaluation results.

Example 4 A seed emulsion was obtained by repeating the same operation as in Example 1 except that the composition was as shown in Table 1. To 800 parts of the seed emulsion, 80 parts of methacrylamide and 40 parts of deionized water were added, and the mixture was heated to 40 ° C., and then 40 parts of a 10% by weight aqueous solution of ammonium persulfate and 40 parts of a 10% by weight aqueous solution of sodium acid sulfite were added. The polymerization reaction was performed for 1.5 hours. Then, the pH was adjusted to 7 with aqueous ammonia,
An aqueous emulsion composition was obtained. Table 2 shows the evaluation results.

Example 5 A seed emulsion was obtained by repeating the same operation as in Example 1 except that the composition was as shown in Table 1. To 700 parts of this seed emulsion, 63 parts of acrylamide, 7 parts of methacrylic acid and 90 parts of deionized water are added, and the mixture is heated to 40 ° C.
Subsequently, 70 parts of a 10% by weight aqueous solution of ammonium persulfate and 1 part of
70 parts of a 0% by weight aqueous sodium sulfite solution was charged, and a polymerization reaction was performed for 1.5 hours. Thereafter, the pH was adjusted to 7 with aqueous ammonia to obtain an aqueous emulsion composition. Table 2 shows the evaluation results.

Example 6 A seed emulsion was obtained by repeating the same operation as in Example 1 except that the composition was as shown in Table 1. To 700 parts of the seed emulsion, 49 parts of methacrylamide and 2 parts of acrylic acid
One part was previously dissolved in 160 parts of deionized water, adjusted to pH 7 with aqueous ammonia, and heated to 40 ° C. Subsequently, 35 parts of a 10% by weight aqueous solution of ammonium persulfate and 10 parts by weight of
35 parts by weight of an aqueous solution of sodium acid sulfite by weight
The polymerization reaction was performed for 1.5 hours. Thereafter, the pH was adjusted to 7 with aqueous ammonia to obtain an aqueous emulsion composition.
Table 2 shows the evaluation results.

Example 7 The same operation as in Example 1 was repeated except that the composition was as shown in Table 1, to obtain a seed emulsion. To 700 parts of this seed emulsion, 120 parts of methacrylamide and 120 parts of deionized water were added, and the methacrylamide was dissolved at 40 ° C.
The temperature was raised to 0 ° C. Subsequently, 60 parts of a 10% by weight aqueous solution of ammonium persulfate was added, and a polymerization reaction was carried out for 1.5 hours.
Thereafter, the pH was adjusted to 7 with aqueous ammonia to obtain an aqueous emulsion composition. Table 2 shows the evaluation results.

Comparative Example 1 A seed emulsion was obtained by repeating the same operation as in Example 1 except that the composition was as shown in Table 1. To 800 parts of the seed emulsion, 80 parts of methacrylamide and 40 parts of deionized water are added, and the mixture is heated to 40 ° C. Then, 40 parts of a 10% by weight aqueous solution of ammonium persulfate and 35 parts of a 10% by weight aqueous solution of sodium acid sulfite are added. The polymerization reaction was performed for 0.5 hours. Then, the pH was adjusted to 7 with aqueous ammonia,
An aqueous emulsion composition was obtained. Table 2 shows the evaluation results.

Comparative Example 2 A seed emulsion was obtained by repeating the same operation as in Example 1 except that the composition was as shown in Table 1. 133 parts of acrylamide, 150 parts of acrylic acid
Parts and 570 parts of deionized water, and heated to 40 ° C.
Subsequently, 70 parts of a 10% by weight aqueous solution of ammonium persulfate,
70 parts of a 10% by weight aqueous sodium sulfite solution was added,
The polymerization reaction was performed for 1.5 hours. Thereafter, the pH was adjusted to 7 with aqueous ammonia to obtain an aqueous emulsion composition.
Table 2 shows the evaluation results.

Comparative Example 3 A seed emulsion was obtained by repeating the same operation as in Example 1 except that the composition was as shown in Table 1. To 700 parts of the seed emulsion, 28 parts of methacrylamide and 42 parts of methacrylic acid were previously dissolved in 90 parts of deionized water, adjusted to pH 7 with aqueous ammonia, and heated to 40 ° C. Subsequently, 70 parts of a 10% by weight aqueous solution of ammonium persulfate and 10 parts by weight of
70 parts by weight of aqueous sodium sulfite solution
The polymerization reaction was performed for 1.5 hours. Thereafter, the pH was adjusted to 7 with aqueous ammonia to obtain an aqueous emulsion. Table 2 shows the evaluation results.

Comparative Example 4 A seed emulsion was obtained by repeating the same operation as in Example 1 except that the composition was as shown in Table 1. To 800 parts of the seed emulsion, 80 parts of methacrylamide and 40 parts of deionized water are added, and the mixture is heated to 40 ° C., and then 40 parts of a 10% by weight aqueous solution of ammonium persulfate and 40 parts of a 10% by weight aqueous solution of sodium sulfite are added to polymerize. Was carried out, but aggregates were generated during the polymerization.

Comparative Example 5 For the purpose of comparison with the aqueous emulsion composition of the present invention, the following seed emulsion was polymerized. After placing 1110 parts of deionized water and 1 part of sodium dodecylbenzenesulfonate in a separable flask equipped with a thermometer, a reflux condenser, a stirrer, and a monomer charger, and replacing with nitrogen gas,
The temperature was raised to 70 ° C. After adding 10 parts of potassium persulfate,
Acrylonitrile 450 parts, n-butyl acrylate 52
0 parts, 30 parts of methacrylic acid emulsified with 400 parts of deionized water and 1 part of sodium dodecylbenzenesulfonate,
It was dropped into the flask continuously over 3 hours. Thereafter, the reaction is further performed at the same temperature for 3 hours, and the pH is adjusted with ammonia water.
7 to obtain a comparative aqueous emulsion composition.
Table 2 shows the evaluation results.

(Evaluation Method) Solvent Resistance (Evaluation Method on Film) Examples 1 to 7 and Comparative Examples 1 to
The aqueous emulsions obtained in 3 and 5 were applied to a glass plate with a bar coater # 60 and dried at 120 ° C. for 5 minutes to prepare a test film. The obtained film was cut into a 30 mm square and weighed (W ₀ ). Next, the film was immersed in a toluene solution for 60 minutes, the toluene was lightly wiped off, and then weighed (W ₁ ). The swelling ratio of the film with toluene was calculated by the following formula.

(Equation 1)

(Evaluation in Pigment Coating Liquid) Each aqueous emulsion composition was mixed with clay (aqueous emulsion / clay solids ratio = 50/50) and adjusted to a solid content of 40% by weight with deionized water. Next, bar coater # on high quality commercial paper
20 and dried at 120 ° C. for 1 minute to prepare a test paper. A toluene solution was applied to the obtained test paper, and the state of penetration of toluene was visually observed. ：: No impregnation △: Some impregnation ×: Many impregnation

Blocking Resistance Each resin was diluted to a solid content of 20%, applied to commercially available high quality paper with a bar coater # 20, and dried at 120 ° C. for 30 seconds to prepare a test paper. The obtained test paper was cut into 10 cm squares, aged under the specified conditions of temperature and humidity for about 4 hours, and then a load of about 30 kg was applied to the coated surfaces together, and after 24 hours, cut out and fused. I checked the degree. ：: no fusion at all △: partial fusion ×: full fusion

Heat Resistance Test paper was prepared in the same manner as in the blocking resistance test, and 10
The test pieces were cut into cm squares, and the applied surfaces were put together under a condition of 120 ° C., a load of about 30 kg was applied, and after 24 hours, the degree of fusion was checked. Table 2 shows the results of the solvent resistance, the blocking resistance, and the heat resistance.

[0045]

[Table 1]

[0046]

[Table 2]

[0047]

[Table 3]

[0048]

[Table 4]

[0049]

The aqueous emulsion composition of the present invention comprises:
By applying to materials such as paper, film, and cloth, very excellent solvent resistance, blocking resistance, and heat resistance can be obtained. Particularly, when used as a back surface treatment agent when producing release paper, an excellent release effect can be obtained.

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Claims (4)

[Claims] 1. In the presence of a seed emulsion (I) seeded with a copolymer containing 10 to 50% by weight of (meth) acrylonitrile in a comonomer, 50 to 100% by weight of (meth) acrylamide is A back surface treating agent for release paper, comprising an aqueous emulsion composition having a two-layer structure obtained by polymerizing at least one aqueous vinyl monomer component (II) contained therein. 2. The ratio of the seed emulsion (I) and the aqueous vinyl monomer component (II) is (50: 5)
0) to (95: 5), a back surface treating agent for release paper, comprising the aqueous emulsion composition according to claim 1. 3. The ratio of the seed emulsion (I) to the aqueous vinyl monomer component (II) is (60: 4)
A back surface treating agent for release paper, comprising the aqueous emulsion composition according to claim 1 which is 0) to (90:10). 4. A radical polymerizable monomer copolymerizable with (meth) acrylonitrile is an acrylic ester, a methacrylic ester, an aromatic vinyl compound, an ethylenically unsaturated carboxylic acid, a hydrophilic monomer, or a conjugated diolefin. Selected from vinyl acetate, vinyl acetate, vinyl chloride and vinylidene chloride
A back surface treatment agent for release paper, comprising the aqueous emulsion according to claim 1 which is a seed.