JPH1150000A - Water-base emulsion coating agent for synthetic resin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating agent which is excellent in applicability and adhesion to a film and forms a film excellent in clarity, resistances to water and oil, and heat sealability by using, as the main ingredient, a water-base acrylic emulsion prepd. by the emulsion polymn. in the presence of a specific free-radical-polymerizable emulsifier. SOLUTION: An emulsion coating agent for synthetic resin films having a surface tension of 20-55 mN/m is obtd. by using, as the main ingredient, an acrylic emulsion which is obtd. by the emulsion polymn. of 80-99.9 wt.% ethylenically unsatd. monomer having no functional group, suitably a monomer mainly comprising an acrylic ester, and 0.1-20 wt.% functional monomer copolymerizable therewith, pref. an ethylenically unsatd. carboxylic acid, in the presence of 0.1-10 wt.% (based on the total monomers) propenyl-group-contg. free-radical-polymerizable emulsifier represented by formula I (wherein R is 6-18C alkyl; X is H, SO3 Na, SO3 NH4 , or SO3 K; and n is 5-120), formula II, or formula III (wherein R is the same as in formula I; M is H, Na, K, or NH4 ; and n is 5-100).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating agent for a synthetic resin film, and more particularly, it is excellent in transparency, water resistance, oil resistance, adhesion to a film and coating property, and furthermore, has a heat sealing property. It also relates to an excellent coating agent.

[0002]

2. Description of the Related Art In recent years, synthetic resin films have been used for many purposes. In addition, the performance required with the expanded use of the film is also diverse. Further, composite films in which a synthetic resin film is laminated with a base material such as another film, paper, aluminum foil, or the like, or a film in which a gas barrier coating agent or the like is applied to the film are also often used.
However, synthetic resin films, particularly polyolefin films, have various problems as a base material for composite films because of their low polarity and poor adhesion. Therefore, development of an adhesive for lamination that strongly adheres to a synthetic resin film such as a polyolefin filament and an anchor coating agent that strongly adheres a gas barrier coating agent to the synthetic resin film are desired. Recently, a coating agent for imparting heat sealing properties to a synthetic resin film is also desired. As a prior art, U.S. Pat. No. 3,753,769 describes a coating agent composed of an aqueous alkaline solution of an acrylic resin. However, satisfactory water resistance cannot be obtained due to the aqueous solution, and the liquid viscosity is low. There is a problem that a high concentration cannot be obtained due to the high concentration. Japanese Patent Publication No. 58-55170 describes a coating agent comprising an acrylic aqueous resin dispersion, but the water resistance and adhesiveness to the film were insufficient due to the emulsifier used to disperse the polymer.
Japanese Patent Publication No. 7-45228 describes a method in which a polymer obtained by solution polymerization is neutralized with an alkali and an aqueous liquid is used without using an emulsifier. However, there is a drawback that a high-volatile matter cannot be obtained, and a stable product cannot be obtained because an emulsifier is not used when neutralizing a part to obtain a dispersion type.

[0003]

There is no conventional coating agent which sufficiently satisfies the adhesiveness to a film, water resistance, oil resistance, coating properties and mechanical stability, and further imparts heat sealing properties. There was nothing. The present invention provides a coating agent which can solve the drawbacks of the prior art and further impart heat sealing properties.

[0004]

This problem is solved by using a coating agent mainly composed of an acrylic aqueous emulsion emulsion-polymerized with a specific radically polymerizable emulsifier. The present invention provides: "1. an ethylenically unsaturated monomer having no functional group;
The main component is an emulsion obtained by emulsion polymerization of a monomer having a functional group copolymerizable therewith using a propenyl group-containing radical polymerizable emulsifier, and has a surface tension of 20 to 55 m.
N / m aqueous emulsion coating agent for synthetic resin films. 2. 2. The aqueous emulsion coating agent for a synthetic resin film according to item 1, wherein the monomer having a functional group is an ethylenically unsaturated carboxylic acid. 3. 2. The aqueous emulsion coating agent for a synthetic resin film according to item 1, wherein the ethylenically unsaturated monomer having no functional group is a (meth) acrylate. 4. The blending ratio of the ethylenically unsaturated monomer having no functional group and the monomer having a functional group is 80 to 99.9% by weight: 0.1 to 20% by weight. An aqueous emulsion coating agent for a synthetic resin film according to any one of the preceding claims. 5. 5. The aqueous emulsion coating for a synthetic resin film according to any one of items 1 to 4, wherein the propenyl group-containing radical polymerizable emulsifier is one or more emulsifiers represented by the following general formulas I to III. Agent. General formula I

[0005]

Embedded image

(R is an alkyl group having 6 to 18 carbon atoms, X is H or SO ₃ Na, SO ₃ NH ₄ , SO ₃ K, n is 5
General formula II

[0007]

Embedded image

(R is an alkyl group having 6 to 18 carbon atoms, M is H or Na, K, NH ₄ , n is an integer of 5 to 100)

[0009]

Embedded image

(R is an alkyl group having 6 to 18 carbon atoms, M is H or Na, K, NH ₄ , n is an integer of 5 to 100) 6. The aqueous emulsion coating agent for a synthetic resin film according to any one of items 1 to 5, wherein the propenyl group-containing radical polymerizable emulsifier is used in an amount of 0.1% by weight to 10% by weight based on all monomers. About.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The emulsion coating agent of the present invention is prepared by adding water, a monomer, and a propenyl group-containing radical polymerizable emulsifier as a dispersion medium to a reaction vessel, heating the mixture with stirring, and emulsifying while adding an initiator. Polymerizes. It is also possible to charge a part of water, a monomer, and a propenyl group-containing radical polymerizable emulsifier and carry out emulsion polymerization while dropping the remaining amount. This gives a milky emulsion. In order to use this as a coating agent, the viscosity and nonvolatile content are adjusted to desired values, and the film is coated on a film using a coating machine such as a gravure roll or an air knife coater.

The ethylenically unsaturated monomer having no functional group used in the present invention includes vinyl acetate, vinyl propylene, vinyl laurate, vinyl stearate, α-
Vinyl esters such as vinyl carboxylate [vinyl pivalate and Veova (trade name of Shell Chemical)]; ethyl (meth) acrylate, methyl (meth) acrylate, n-butyl (meth) acrylate (Meth) acrylic acid esters such as isobutyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate; methyl crotonate, ethyl crotonate and maleic acid Unsaturated carboxylic acid esters or unsaturated unsaturated polycarboxylic acid esters other than the above, such as diethyl acrylate and dibutyl maleate; (meth) acrylonitrile, styrene, methylstyrene, chlorostyrene, vinyl chloride, vinylidene chloride,
One or more than one such as ethylene is used. In the present invention, those having (meth) acrylic acid ester as a main component are particularly preferable. Examples of the ethylenically unsaturated monomer having a radical copolymerizable functionality used in the present invention include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, maleic anhydride, maleic acid monoester and the like. Unsaturated carboxylic acids or unsaturated polycarboxylic acid derivatives; unsaturated carboxylic acid amides such as (meth) acrylamide, N-methylol methacrylamide and the like;
Unsaturated glycidyl compounds such as methylol unsaturated carboxylic acid amide and glycidyl (meth) acrylate; alkylolated unsaturated compounds such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate and hydroxyvinyl ether; diallyl phthalate, divinylbenzene And at least one of divinyl or diallyl compounds, unsaturated compounds having an alkoxysilyl group and the like. Among these, an ethylenically unsaturated carboxylic acid is mentioned as an important component for stabilizing particles.
This is because unsaturated carboxylic acids are easily oriented on the particle surface,
This is because when the pH is on the alkaline side, hydrogen atoms dissociate to form an electric double layer and contribute to stabilization of the particles.

The ethylenically unsaturated monomer having no functional group and the ethylenically unsaturated monomer having a functional group copolymerizable therewith are appropriately selected depending on the kind of the film to be used and required physical properties. Used. For example, in order to increase water resistance and oil resistance, a functional group-containing monomer which is easily crosslinked should be selected. The use ratio of the ethylenically unsaturated monomer having no functional group and the ethylenically unsaturated monomer having a functional group copolymerizable therewith is determined depending on which monomer is used in combination. 80 to 99.9% by weight of an ethylenically unsaturated monomer having no functionality with respect to all monomers, and 0.1 to 10% by weight of an ethylenically unsaturated monomer having a copolymerizable functionality. 20% by weight. When the amount of the unsaturated monomer having a functional group is less than 0.1% by weight, the particles are not sufficiently stabilized or crosslinked by the functional group, and when the amount is more than 20% by weight, the adhesive strength and water resistance are remarkably reduced. Absent.

The radical polymerizable emulsifier containing a propenyl group used in the present invention is represented by the following general formulas I to III. General formula I

[0015]

Embedded image

(R is an alkyl group having 6 to 18 carbon atoms, X is H or SO ₃ Na, SO ₃ NH ₄ , SO ₃ K, n is 5
General formula II

[0017]

Embedded image

(R is an alkyl group having 6 to 18 carbon atoms, M is H or Na, K, NH4, and n is an integer of 5 to 100)

[0019]

Embedded image

(R is an alkyl group having 6 to 18 carbon atoms, M is H or Na, K, NH ₄ , n is an integer of 5 to 100)

By using a radical polymerizable emulsifier containing no propenyl group, it is required for a synthetic resin film coating agent. Adhesion to film, water resistance,
Oil resistance, coating properties and mechanical stability can be sufficiently satisfied, and heat sealing properties can be imparted.
The ionicity of the propenyl group-containing radical polymerizable emulsifier is not particularly limited, but an anionic one is preferable. The use amount of the propenyl group-containing radical polymerizable emulsifier is preferably 0.1 to 10% by weight based on all monomers. When the amount is less than 0.1% by weight, the emulsifying power is insufficient, the polymerization stability is insufficient, and the mechanical stability and storage stability of the emulsion are also insufficient. If it is more than 10% by weight, the water resistance decreases due to an increase in hydrophilicity. Other emulsifiers can be used together with the propenyl group-containing radical polymerizable emulsifier. For example, a propenyl group-containing radical polymerizable emulsifier, a nonionic emulsifier having no radical polymerizability, an anionic emulsifier, a water-soluble polymer compound such as polyvinyl alcohol or hydroxyethyl cellulose having a protective colloid function, and a water-soluble polymer such as polyacrylic acid Vinyl polymer and the like. When these are used in combination, it is necessary to use them within a range that does not inhibit the effect of using the propenyl group-containing radical polymerizable emulsifier. The amount used varies depending on the combination, but the preferred range is from 0.01 to 0.01 of the propenyl group-containing radical polymerizable emulsifier.
The range is 10 times.

The emulsion polymerization method is not particularly limited. The whole amount is charged at once and the temperature is raised to a desired temperature while stirring, and a polymerization initiator is appropriately added to carry out polymerization, or a part is charged into a reaction vessel, a polymerization initiator is added, initial polymerization is carried out, and then the remaining amount is dropped. The polymerization can be carried out by adding a polymerization initiator. The latter is more desirable if a fine particle size is required. The obtained emulsion can be used as it is as a coating agent. In addition, the water content can be adjusted to adjust the nonvolatile content and the viscosity. When an unsaturated carboxylic acid is copolymerized, part or all of the copolymer can be neutralized with an alkali and used as a so-called hydrosol.

If desired, an adhesion promoting catalyst such as paratoluenesulfonic acid and titanyl sulfate, a wax, a filler,
Additives such as antistatic agents, lubricants and ultraviolet absorbers can also be added. In order to coat the coating agent of the present invention uniformly and thinly on a synthetic resin film as a base material, the surface tension of the coating agent needs to be 20 to 55 mN / m. This surface tension is measured by a Dunui surface tension measurement method. The surface tension of a synthetic resin film is generally 25 to 45 mN / m when the surface is untreated, and is at most about 57 mN / m even when surface treatment such as corona treatment and plasma treatment is performed. When the surface tension of the coating agent exceeds the surface tension of the synthetic resin film, the wettability and adhesion to the film are significantly deteriorated. Therefore, the upper limit needs to be 55 mN / m. As an example, in the case of a polyolefin film, the surface tension is generally 31 to 52 mN / m. Therefore, the surface tension of the coating agent needs to be 50 mN / m or less, preferably 45 mN / m or less. Further, in order to lower the surface tension below 20 mN / m, a remarkably large amount of wetting agent is required, which adversely affects physical properties, which is not preferable.

To summarize the characteristics of the coating agent of the present invention, since the propenyl group-containing radically polymerizable emulsifier is incorporated into the polymer skeleton, the coating agent is excellent in water resistance and also excellent in oil resistance due to the hydrophilic group of the emulsifier. Further, the heat sealability is good. Since the propenyl group-containing radically polymerizable emulsifier is fixed on the surface of the polymer particles in the form of a copolymer, even when diluted to a low nonvolatile content, it has excellent dispersion stability and mechanical stability. However, since the stability is maintained, it is excellent in film forming property and adhesion to a synthetic resin film. Since the form is an aqueous dispersion, the liquid viscosity can be lowered, so that high non-volatile differentiation is possible as compared with the aqueous solution type, and troubles such as foaming can be avoided by applying the coating with a low viscosity. . Aqueous resin dispersions had the disadvantage that the film-forming properties were inferior when the glass transition point of the polymer was higher than in the aqueous solution type.However, if the unsaturated carboxylic acid was copolymerized and neutralized with an alkali to form a hydrosol, Even a polymer having a high glass transition point does not cause film formation failure. At this time, since a radical polymerizable emulsifier containing a propenyl group is used, the solubility in alkali is excellent.

[0025]

【Example】

Example 1 50 parts by weight of water, 5 parts by weight of methyl methacrylate, 2 parts by weight of ethyl acrylate, 1 part by weight of methacrylic acid, and a propenyl group-containing radical polymerizable emulsifier 0.1 part by weight in a reaction vessel.
5 parts by weight were charged and the temperature was raised with stirring, and 1.0 part by weight of a peroxide-based initiator was added to carry out initial polymerization. Next, a monomer emulsion obtained by emulsion polymerization of 40 parts by weight of water, 55 parts by weight of methyl methacrylate, 28 parts by weight of ethyl acrylate, 4 parts by weight of methacrylic acid, and 1.5 parts by weight of a propenyl group-containing radically polymerizable emulsifier was applied for 2 hours. , And the polymerization is progressed by adding an initiator every 30 minutes. After completion of the dropwise addition, the mixture is stirred and aged while maintaining the temperature to complete the reaction. To this, 130 parts by weight of water and 10% ammonia water 7
Parts by weight were added. The resulting emulsion has a non-volatile content of 30%
Met. To this, water was added to adjust the non-volatile content to 10% to obtain a coating agent. Its surface tension is 45 mN / m
Met.

Example 2 50 parts by weight of water, 3 parts by weight of methyl methacrylate, 2 parts by weight of ethyl acrylate, 1.
0 parts by weight, 0.5 parts by weight of a propenyl group-containing radically polymerizable emulsifier, and 0.5 parts by weight of a radically polymerizable emulsifier having no propenyl group were charged, and the temperature was raised while stirring to obtain a peroxide-based initiator. 0 parts by weight are added to cause initial polymerization. Next, 40 parts by weight of water, 47 parts by weight of methyl methacrylate,
38 parts by weight of ethyl acrylate, 2.0 of methacrylic acid
Parts by weight, and a monomer emulsion obtained by emulsion polymerization of 1.0 part by weight of a propenyl group-containing radical polymerizable emulsifier and 1.0 part by weight of a radical polymerizable emulsifier having no propenyl group were added dropwise over 2 hours, and every 30 minutes The polymerization is advanced by adding an initiator. After completion of the dropwise addition, the mixture is stirred and aged while maintaining the temperature to complete the reaction. To this, 130 parts by weight of water and 7.0 parts by weight of 10% aqueous ammonia were added. The obtained emulsion had a nonvolatile content of 30%. To this, water was added to adjust the non-volatile content to 10% to obtain a coating agent.
Its surface tension was 44 mN / m.

EXAMPLE 3 50 parts by weight of water, 5 parts by weight of methyl methacrylate, 3 parts by weight of ethyl acrylate, 1 part by weight of methacrylic acid, and a propenyl group-containing radical polymerizable emulsifier 0.1 part by weight in a reaction vessel.
5 parts by weight and 0.5 parts by weight of an anionic emulsifier having no radically polymerizable group are charged and heated while stirring, and 1.0 part by weight of a peroxide-based initiator is added to carry out initial polymerization. Then water 4
0 parts by weight, 55 parts by weight of methyl methacrylate, 28 parts by weight of ethyl acrylate, 4 parts by weight of methacrylic acid, 1.0 part by weight of a radical polymerizable emulsifier containing a propenyl group, an anionic emulsifier having no radical polymerizable group.
A monomer emulsion obtained by emulsion polymerization of 5 parts by weight is added dropwise over 2 hours, and an initiator is added every 30 minutes to advance the polymerization. After completion of the dropwise addition, the mixture is stirred and aged while maintaining the temperature to complete the reaction. To this, 130 parts by weight of water and 7.0 parts by weight of 10% aqueous ammonia were added. The obtained emulsion had a nonvolatile content of 30%. To this, water, wax emulsion, and organic fine particle filler were added to reduce the nonvolatile content to 10%.
% To give a coating agent. Its surface tension is 4
It was 4 mN / m.

Comparative Example The procedure of Example 1 was repeated except that sodium polyoxyethylene nonylphenyl ether was used as the emulsifier.
An emulsion having a nonvolatile content of 30% was obtained. Water was added thereto to adjust the non-volatile content to 10% to obtain a coating agent.

Evaluation 1. Polymerization stability: Does not block during the polymerization reaction,
It is checked whether a uniform emulsion is obtained after the polymerization reaction, and whether there is no generation of aggregates when filtered. 2. Mechanical stability: With a Malon type device specified in JIS K 6392, the number of rotations is 2000 rpm, the load is 10
The test is performed under the conditions of Kg and time of 10 minutes, and the mechanical stability is ranked based on the amount of the formed aggregate. ◎: Coagulated mass (mg / 100 g) is 2 or less ○: Coagulated mass (mg / 100 g) is 2 to 10 Δ: Coagulated mass (mg / 100 g) is 10 to 100 ×: Coagulated mass (mg / 100 g) is 100 or more 3. Coatability To surface corona treated polypropylene film, solid content 2.
A coating agent diluted to 10% so as to be 0 g / m ² is applied, and dried at 80 ° C. for 30 seconds. The coating property is evaluated based on the two points of wettability to the film and film forming property. Film wettability ○: No repelling / fish eye △: Fish eye / pinball present ×: Repelling film forming ○: Transparent film forming △: Slightly cloudy ×: Whitening 2. Water resistance After immersing the coating film prepared in the evaluation of coatability in water for 72 hours, removing the water on the surface,
Transparency was observed. In addition, a cellophane adhesive tape was pressure-bonded, rapidly peeled off, and the adhesion of the coated surface was observed. Transparency ○: Transparent ×: Whitening Adhesion ○: Coating surface peels ×: Coating surface does not peel 2. Oil resistance After dipping in the high-boiling-point petroleum-based solvent (No. 5 solvent) and leaving it at 40 ° C. for 72 hours, the surface solvent is wiped off and the state of the surface is observed. ：: The film remains smooth ×: The film swells and wrinkles are generated Heat sealing property 3. The coated surfaces of the coating films prepared in the above are combined and heat-sealed under the conditions of 120 ° C., 1 kg pressure, and 0.5 seconds, and then the sealing strength is measured at a pulling speed of 100 mm / min. ：: Measured value of 80 gf / 15 mm or more ×: Measured value of less than 80 gf / 15 mm The evaluation results are shown in Table 1.

[0030]

[Table 1]

[0031]

The coating agent of the present invention, when coated on a synthetic resin film, has excellent adhesiveness and coatability to the film, and the formed film has transparency, water resistance,
It has excellent oil resistance and heat sealing properties.

Claims (6)

[Claims] An emulsion obtained by emulsion-polymerizing an ethylenically unsaturated monomer having no functional group and a monomer having a functional group copolymerizable therewith with a propenyl group-containing radical polymerizable emulsifier. And the surface tension is 20 to
An aqueous emulsion coating agent for a synthetic resin film having a viscosity of 55 mN / m. 2. The aqueous emulsion coating agent for a synthetic resin film according to claim 1, wherein the monomer having a functional group is an ethylenically unsaturated carboxylic acid. 3. The aqueous emulsion coating agent for a synthetic resin film according to claim 1, wherein the ethylenically unsaturated monomer having no functional group is a (meth) acrylic acid ester. 4. The compounding ratio of an ethylenically unsaturated monomer having no functional group to a monomer having a functional group is 80 to 99.
The aqueous emulsion coating agent for a synthetic resin film according to any one of claims 1 to 3, wherein the amount is 9% by weight: 0.1 to 20% by weight. 5. The synthetic resin according to claim 1, wherein the propenyl group-containing radically polymerizable emulsifier is one or more emulsifiers represented by the following general formulas I to III. Aqueous emulsion coating agent for film. Formula I (R is an alkyl group having 6 to 18 carbon atoms, X is H or SO
₃ Na, SO ₃ NH ₄ , SO ₃ K, n is an integer of 5 to 120) General formula II General formula III (R is an alkyl group having 6 to 18 carbon atoms, M is H or N
a, K, NH ₄ , and n are integers of 5 to 100. (R is an alkyl group having 6 to 18 carbon atoms, M is H or N
a, K, NH4, and n are integers of 5 to 100) 6. The aqueous solution for a synthetic resin film according to claim 1, wherein the propenyl group-containing radical polymerizable emulsifier is used in an amount of 0.1% by weight to 10% by weight based on all monomers. Emulsion coating agent.