JPH09296014A - Vinylidene chloride copolymer resin latex - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vinylidene chloride copolymer resin latex which is hard and durable and forms a coating film excellent in adhesion under a high temp. atmosphere. SOLUTION: This vinylidene chloride copolymer resin latex is obtd. by emulsion polymerization of a monomer mixture of 86-94wt.% vinylidene chloride, 0.1-1.2wt.% vinyl monomer contg. a carboxylic group, and 4.8-13.9wt.% at least one vinyl monomer which is copolymerizable with these monomers, and the electrical resistance of the latex at 25 deg.C is 2,000-20,000Ω.m, and the melt viscosity at 170 deg.C of the powder obtd. by freeze drying of the latex is not more than 140Pa.s.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is applied to a plastic film used for food packaging, silver halide photographic light-sensitive materials, etc. to form a hard coating film having excellent durability, which is treated under boiling water or in a high humidity atmosphere. The present invention relates to a vinylidene chloride-based copolymer resin latex having good adhesiveness to a plastic film substrate without the presence of a solvent-based adhesive layer even under a condition of being left for a long time.

[0002]

2. Description of the Related Art Vinylidene chloride copolymer resin latex is coated on a plastic film such as polypropylene, polyester, nylon and the like, and is used heavily for significantly improving its gas and water vapor barrier properties. For this vinylidene chloride copolymer resin latex, a hard coating film is required to be formed in order to improve durability such as blocking resistance and scratch resistance. Further, the latex is required to have good adhesiveness to the plastic film substrate even under the condition that the formed coating film is left to stand in boiling water treatment or high humidity atmosphere for a long time. ing.

That is, for vinylidene chloride copolymer resin latex, a hard coating film having excellent durability is formed, and even under conditions where it is left to stand in boiling water treatment or high humidity atmosphere for a long time, It is required to have good adhesiveness with a plastic film substrate. In order to meet these requirements, the following improvements have been attempted. For example, in the case of forming a hard coating film with excellent durability, in order to improve the adhesiveness with the plastic film substrate after boiling water treatment, vinylidene chloride-based dialysis treated using a diaphragm made of an appropriate material A copolymer resin latex is proposed in Japanese Patent Publication No. Sho 48-10941, and it is disclosed that it has good adhesiveness to a plastic film substrate even after being treated with boiling water. However, under the condition of being left in a high humidity atmosphere for a long time, it was difficult to obtain the adhesiveness targeted by the present invention without the interposition of the adhesion promoter layer.

Similarly, when a hard coating film having excellent durability is formed, the adhesion to the plastic film substrate after boiling water treatment is improved by dialysis treatment with a cellulose membrane. A vinylidene chloride-based copolymer resin latex containing vinylidene chloride monomer units and methacrylic acid monomer units in the following ratio was proposed in Japanese Examined Patent Publication No. 59-41660, and even after being treated with boiling water, a plastic film base It has been disclosed that it has good adhesion to wood. However, under the condition of being left in a high humidity atmosphere for a long time, it was difficult to obtain the adhesiveness targeted by the present invention without the intervention of the solvent-based adhesive layer. A method of interposing a solvent-based adhesive layer as an anchor coat in order to assist the adhesiveness is generally known. However, in response to solvent regulations resulting from environmental problems in recent years, it is required to achieve a high degree of adhesion between a plastic film substrate and the coating film without using a solvent-based adhesive.

Further, when a hard coating film having excellent durability is formed, the weight average molecular weight of 5000 is used for improving the adhesiveness with a plastic film substrate in a high humidity atmosphere.
A vinylidene chloride-based copolymer resin latex characterized by being 0 or less is proposed in JP-A-4-184431, and even after being left for 3 days in a high humidity atmosphere of 25 ° C. and 85% RH, it is solvent-based. It is disclosed to have good adhesion to plastic film substrates without the interposition of an adhesive layer. However, it was difficult to obtain the adhesiveness aimed at by the present invention under severe conditions, for example, in which a high humidity atmosphere of 25 ° C. and 100% RH was left for 5 days.

[0006]

The object of the present invention is to coat a plastic film used for food packaging, silver halide photographic light-sensitive materials and the like to form a hard coating film having excellent durability and at the same time boiling water. To provide a vinylidene chloride-based copolymer resin latex having good adhesion to a plastic film substrate without the intervention of a solvent-based adhesive layer even under the condition of being treated or left in a high-humidity atmosphere for a long time. The purpose is.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, a vinylidene chloride copolymer resin latex having a specific electric resistivity and melt viscosity solves the above problems. The present invention has been completed and the present invention has been completed. That is, the present invention relates to a vinylidene chloride monomer of 86 to 94% by weight, a carboxyl group-containing vinylic monomer of 0.1 to 1.2% by weight, and one or more other vinylic monomers copolymerizable therewith. Monomer 4.
A vinylidene chloride copolymer resin latex obtained by emulsion polymerization of a monomer mixture consisting of 8 to 13.9% by weight, wherein the latex has an electrical resistivity of 2 at 25 ° C.
2,000 to 20,000 Ω · m, and the melt viscosity at 170 ° C. of the powder obtained by freeze-drying the latex is 1
It relates to a vinylidene chloride-based copolymer resin latex, which is 40 Pa · s or less.

The content of vinylidene chloride of the present invention is 86-9.
4% by weight is suitable. If it is less than 86% by weight, the crystallinity is low, and the coating film hardness aimed at by the present invention cannot be exhibited. On the other hand, if it exceeds 94% by weight, the copolymer will be crystallized immediately after the polymerization, and the latex particles will become hard, resulting in poor film formability. It is preferably 88% by weight to 93% by weight, and more preferably 89% by weight to 92% by weight. In the present invention, a vinyl monomer containing a carboxyl group is essential. When the carboxyl group-containing vinyl monomer is not used, the adhesiveness with the plastic film substrate in the normal state cannot be expressed.

The content of the vinyl monomer containing a carboxyl group of the present invention is 0.1 to 1.2% by weight. 0.1% by weight
If it is less than 1.2%, the adhesiveness to the plastic film substrate in the normal state is deteriorated. On the other hand, if it exceeds 1.2% by weight, the flowability when coating / drying the latex is deteriorated, and it is Adhesiveness is reduced. More preferably 0.2
~ 1.0% by weight. Examples of the carboxyl group-containing vinyl monomer include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid and fumaric acid. The content of the other copolymerizable vinyl monomer of the present invention is 4.8 to 13.9% by weight. 4.8
If it is less than wt%, the film formability will be poor. In addition, 13.9%
If it exceeds, the coating film hardness that the present invention aims at cannot be expressed.

The copolymerizable vinyl-based monomer is, for example, ethylene-based α, β such as methyl acrylate, propyl acrylate, butyl acrylate, or methyl methacrylate.
-Alkyl ester monomers of unsaturated carboxylic acids. Further, for example, a monomer having a nitrile group such as acrylonitrile or methacrylonitrile can be similarly mentioned. Also, hydroxyalkyl esters of ethylene α, β-unsaturated carboxylic acids, amide compounds of ethylene α, β-unsaturated carboxylic acids such as acrylamide, vinyl esters such as vinyl chloride and vinyl acetate, and vinyl ethers such as vinyl methyl ether. And allyl esters such as allyl acetate, and allyl ethers such as allyl methyl ether. Further, styrene compounds are also included.

The electrical resistivity (Ω ·
m) is 25 in accordance with JIS K-0101 12.
The electric conductivity (S / m) at ° C was measured and the reciprocal thereof was taken. The vinylidene chloride copolymer resin latex of the present invention has an electric resistivity of 2000 at 25 ° C.
Up to 20000 Ω · m. Electric resistivity is 200
When it is less than 0 Ω · m, the hydrophilic substance in the latex is not sufficiently removed, and the target adhesiveness to the plastic film substrate in a high humidity atmosphere cannot be obtained. Also, 200
If it exceeds 00 Ω · m, the stability of the latex decreases, which is not preferable.

The preferred electrical resistivity at 25 ° C. is 30.
The range is from 00 to 15000 Ω · m. Particularly preferred is the range of 3000 to 8000 Ω · m. In order to obtain the vinylidene chloride copolymer resin latex of the present invention, the monomer mixture is polymerized by ordinary emulsion polymerization or the like, and the obtained latex is dialyzed to adjust the electrical resistivity at 25 ° C. To manufacture. Examples of the type of dialysis membrane used for dialysis treatment include those made of regenerated cellulose, polyacrylonitrile, polysulfone, or the like. The latex is placed in a dialysis tube composed of these membranes and allowed to stand in ion-exchanged water, and the ion-exchanged water is slowly stirred for dialysis treatment.

The type of polymerization initiator, surfactant, etc. used in the vinylidene chloride copolymer resin latex of the present invention is not particularly limited, but these additives are produced from the latex even after the above-mentioned dialysis treatment. It may remain in the coating film and cause a decrease in the adhesiveness with the plastic film substrate in a high humidity atmosphere, so it is desirable that the amount used is as small as possible. The melt viscosity at 170 ° C. of the present invention is a value obtained by measuring 2 g of a freeze-dried latex product under the following conditions.

[0014] Plunger: Diameter 1.0 cm ² Die: D / L = 1mm / 2mm load: 10 kg Temperature: 170 ° C. preheating: 100 seconds Measure Position: 7Mm～10mm

The vinylidene chloride copolymer resin latex of the present invention has a polymer powder obtained by freeze-drying the latex having a melt viscosity at 170 ° C. of 140 Pa · s or less. If this value exceeds 140 Pa · s,
The flowability when applying and drying latex decreases,
The target adhesiveness to the plastic film substrate in a high humidity atmosphere cannot be obtained. Particularly preferable is a melt viscosity of 100 Pa · s or less. 170 referred to in the present invention
The vinylidene chloride copolymer resin having a melt viscosity at 140C of 140 Pa · s or less can be obtained by adjusting the weight average molecular weight according to the monomer composition.

[0016]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. In Examples and Comparative Examples, parts and% are by weight unless otherwise specified. The measured values used in the examples of the present invention were measured by the following methods.

(A) Preparation of coated film A biaxially stretched polyester film having a thickness of 100 μ and subjected to corona discharge treatment, and a vinylidene chloride-based copolymer resin latex to be dried using a Mayer bar to achieve a dry film thickness of 1 μ And dried in a hot air circulation dryer at 180 ° C. for 2 minutes. Gelatin was coated on the formed coat layer using a Meyer bar so as to have a dry film thickness of 0.2 μm, and dried in a hot air circulation dryer at 170 ° C. for 2 minutes. Further, gelatin was applied to the target using a Meyer bar so as to have a dry film thickness of 5 μm, and left to dry in a room kept at 20 ° C. for one day. The coating film thus prepared was subjected to an aging treatment at 40 ° C. for one day.

(B) 25 ° C. electrical resistivity The electrical conductivity (S / m) at 25 ° C. is measured based on JIS K-0101 12, and the reciprocal thereof is taken. (C) Melt Viscosity at 170 ° C. Melt viscosity of 2 g of the freeze-dried latex product was measured by a flow tester [CFT-500 manufactured by Shimadzu Corporation] under the following conditions.

[0019] Plunger: Diameter 1.0 cm ² Die: D / L = 1mm / 2mm load: 10 kg Temperature: 170 ° C. preheating: 100 seconds Measure Position: created in 7Mm～10mm (d) high-humidity treatment (a) above Coated film at 25 ℃, 100%
After storing in an RH atmosphere for 5 days, it was taken out and sandwiched between filter papers to absorb water droplets adhering to the surface of the coated film.

(E) Adhesiveness with plastic film substrate (adhesiveness after high-humidity treatment) 15 minutes after the treatment of (d) above, the coated film surface is razored vertically at 5 mm intervals. Make 7 notches each to make 36 squares, and stick adhesive tape (Nitto tape: product name, manufactured by Nitto Denki Kogyo Co., Ltd.) on this and quickly peel off in 180 ° direction. This operation is performed within 30 minutes after the treatment (d). By this method, if the unpeeled portion is 100%, ◎, 95%
The above items were marked as ∘ to ⊚, 80% or more as ◯, 60% or more as Δ, and less than 60% as x. Adhesive strength sufficient for practical use is classified into ○ or higher among the above five levels.

(F) Coating hardness The strength and elongation of the coating obtained by drying the vinylidene chloride copolymer resin latex was measured under the following conditions. Sample preparation: Latex is coated on an aluminum foil using a Mayer bar and dried at 180 ° C. for 2 minutes. Repeat until the target film thickness is 30 μm. The coating film is peeled off from the aluminum foil to obtain a cast film.

Sample history: 40 ° C., left for 1 day. Measuring machine: Tensile tester [Tensilon UTM-4L manufactured by Toyo Seiki Co., Ltd.] Measuring conditions: temperature 70 ° C., grasping length 50 mm, pulling speed 50 mm / min Evaluation standard: initial elastic modulus (5% modulus) 10 kgf /
mm ² or more is ◎, 6 kgf / mm ² or more is ○, 3 kgf
/ Mm ² or more was evaluated as Δ, and less than that was evaluated as x. Adhesive strength that can withstand practical use is classified into ⊚ and ∘ in the above four stages.

Example 1 A vinylidene chloride copolymer resin latex was produced by the following method. 87 parts of water, 0.25 parts of sodium alkyl sulfonate (Merosolate H: product name of Bayer, trade name, the same applies hereinafter) and sodium bisulfite 0.1 in a pressure-resistant reactor provided with a glass lining.
After degassing, the temperature of the contents was adjusted to 53.5
C. Vinylidene chloride (VDC) 9 in a separate container
1.5 parts, methyl methacrylate (MMA) 4 parts, methacrylonitrile (MAN) 4 parts and methacrylic acid (MA
A) 0.5 part was metered and mixed to prepare a monomer mixture. The monomer mixture was continuously metered into the pressure-resistant reactor for 20 hours. In parallel, sodium persulfate was continuously and quantitatively injected so that the total amount became 0.3 part.

During this period, the content was kept at 53.5 ° C. and the reaction was allowed to proceed until the internal pressure dropped sufficiently. A 15% aqueous solution of sodium alkyl sulfonate was added to the latex thus obtained, and the gas-liquid surface tension at 20 ° C. was 42 mN /
It was adjusted to be m. Thereafter, unreacted monomers were removed by steam stripping. Next, using a dialysis membrane with a cut-off molecular weight of 10,000, in which the membrane material is cellulose,
Dialysis was performed for 2 hours. Dialysis treatment using
A latex having an electric resistivity of 3000 Ω · m at 5 ° C. was obtained. Table 1 shows the electrical resistivity, the melt viscosity of the freeze-dried powder of the latex at 170 ° C., the performance of the applied coating film, and the like of the resulting vinylidene chloride copolymer resin latex, together with the composition and performance of the latex. .

(Example 2) 86.0 parts of vinylidene chloride (VDC) and methyl methacrylate (MM) were mixed with the monomer mixture.
A) 6.75 parts, methacrylonitrile (MAN) 6.7
The same procedure as in Example 1 was carried out except that 5 parts and 0.5 part of methacrylic acid (MAA) were measured and mixed. The properties and the like of the obtained latex are shown in Table 1 as in Example 1. (Example 3) Vinylidene chloride (VD) was added to the monomer mixture.
C) 94.0 parts, methyl methacrylate (MMA) 2.7
The same procedure as in Example 1 was carried out except that 5 parts, 2.75 parts of methacrylonitrile (MAN) and 0.5 part of methacrylic acid (MAA) were measured and mixed. The properties and the like of the obtained latex are shown in Table 1 as in Example 1.

(Example 4) 91.5 parts of vinylidene chloride (VDC) and methyl methacrylate (MM) were mixed with the monomer mixture.
A) The same as Example 1, except that 4.2 parts, methacrylonitrile (MAN) 4.2 parts and methacrylic acid (MAA) 0.1 parts were measured and mixed. The performance and the like of the obtained latex are shown in Table 1 as in Example 1. (Example 5) Vinylidene chloride (VD) was added to the monomer mixture.
C) 91.5 parts, methyl methacrylate (MMA) 3.6
The same procedure as in Example 1 was performed except that 5 parts, 3.65 parts of methacrylonitrile (MAN) and 1.2 parts of methacrylic acid (MAA) were measured and mixed. The properties and the like of the obtained latex are shown in Table 1 as in Example 1.

(Example 6) 91.5 parts of vinylidene chloride (VDC) and methyl methacrylate (MM) were mixed with the monomer mixture.
Example 1 was carried out in the same manner as in Example 1 except that 4 parts of A), 4 parts of methacrylonitrile (MAN) and 0.5 parts of acrylic acid (AA) were measured and mixed. The properties and the like of the obtained latex are shown in Table 1 as in Example 1. (Example 7) The same procedure as in Example 1 was performed except that a dialysis membrane having a cut-off molecular weight of 50,000 and made of polyacrylonitrile was used and the dialysis treatment was performed for 1 hour. The properties and the like of the obtained latex are shown in Table 1 as in Example 1.

(Example 8) A dialysis membrane having a cut-off molecular weight of 50,000 and made of polyacrylonitrile was used.
The same procedure as in Example 1 was carried out except that the dialysis treatment was performed for a time. The properties and the like of the obtained latex are shown in Table 1 as in Example 1. (Example 9) The same procedure as in Example 1 was carried out except that a dialysis membrane having a cut-off molecular weight of 50,000 and made of polyacrylonitrile was used and the dialysis treatment was performed for 4 hours. The properties and the like of the obtained latex are shown in Table 1 as in Example 1. (Example 10) The same procedure as in Example 1 was carried out except that a dialysis membrane having a cut-off molecular weight of 50,000 and made of polyacrylonitrile was used and the dialysis treatment was performed for 10 hours. The properties and the like of the obtained latex are shown in Table 1 as in Example 1.

[0029]

[Table 1]

In Examples 7 to 10, as shown in the column of adhesiveness after high-humidity treatment in Table 1, dialysis treatment is performed using a dialysis membrane having a cut-off molecular weight of 50,000 and made of polyacrylonitrile. It can be seen that there is an outstanding improvement effect after the high humidity treatment. Surprisingly, the effect is larger than that when the dialysis treatment is performed with the cellulose membrane. (Example 11) The same procedure as in Example 1 was performed except that the amount of sodium persulfate was changed to 0.25 part. The properties of the obtained latex are shown in Table 2 as in Example 1.

(Example 12) 90.0 parts of vinylidene chloride (VDC) and methyl methacrylate (M
MA) 4 parts, methyl acrylate (MA) 4 parts, acrylonitrile (AN) 1.7 parts and methacrylic acid (MA
A) The same as Example 1, except that 0.3 parts were prepared by weighing and mixing. The properties of the obtained latex are shown in Table 2 as in Example 1. (Example 13) Vinylidene chloride (VD
C) 90.0 parts, methyl methacrylate (MMA) 4 parts,
Methyl acrylate (MA) 4 parts, acrylonitrile (A
N) 1.7 parts and methacrylic acid (MAA) 0.3 parts were prepared by weighing and mixing, and using a dialysis membrane having a cut-off molecular weight of 50,000 and made of polyacrylonitrile as a membrane material,
The same procedure as in Example 1 was performed except that the dialysis treatment was performed for 1.5 hours. The properties of the obtained latex are shown in Table 2 as in Example 1.

COMPARATIVE EXAMPLE 1 83.5 parts of vinylidene chloride (VDC) and methyl methacrylate (MM) were mixed with the monomer mixture.
A) The same as Example 1 except that 8 parts, methacrylonitrile (MAN) 8 parts and methacrylic acid (MAA) 0.5 parts were prepared by measuring and mixing. The properties of the obtained latex are shown in Table 2 as in Example 1. As shown in the column of coating film hardness in Table 2, when the vinylidene chloride monomer is lower than 86% by weight, the crystallinity is low and the coating film hardness aimed at by the present invention cannot be expressed.

(Comparative Example 2) The same procedure as in Example 1 was carried out except that no dialysis treatment was carried out. The properties of the obtained latex are shown in Table 2 as in Example 1. As shown in the adhesiveness after high-humidity treatment in Table 1, the target adhesiveness cannot be obtained without dialysis treatment. (Comparative Example 3) The same procedure as in Example 1 was carried out except that a dialysis membrane having a cut-off molecular weight of 50,000 and made of polyacrylonitrile was used and subjected to dialysis treatment for 6 hours. The properties of the obtained latex are shown in Table 2 as in Example 1. Table 2
As shown in the column of "Adhesion under high humidity", when the electrical resistivity at 25 ° C is less than 2000 Ω · m, the effect of improving the adhesiveness after the high humidity treatment is not exhibited.

(Comparative Example 4) The same procedure as in Example 1 was carried out except that a dialysis membrane composed of polyacrylonitrile as a membrane material and having a cut-off molecular weight of 50,000 was used and dialysis treatment was performed for 11 hours. The properties of the obtained latex are shown in Table 2 as in Example 1. As shown in the column of adhesiveness under high humidity in Table 2, the stability of the latex decreases when the electrical resistivity at 25 ° C exceeds 20,000 Ω · m, and the adhesion after high humidity treatment decreases due to poor film formation. To do. (Comparative Example 5) The same operation as in Example 1 was carried out except that the amount of sodium persulfate was changed to 0.23 part. The properties of the obtained latex are shown in Table 2 as in Example 1. Table 2
As shown in the column of “Adhesiveness after high humidity treatment”, if the melt viscosity at 170 ° C. exceeds 140 Pa · s, the target adhesiveness cannot be obtained.

Comparative Example 6 A monomer mixture was prepared by adding 90.0 parts of vinylidene chloride (VDC) and methyl methacrylate (MM).
A) 4 parts, methyl acrylate (MA) 4 parts, acrylonitrile (AN) 1.7 parts and methacrylic acid (MAA)
The same procedure as in Example 1 was performed, except that 0.3 part was prepared by weighing and mixing and no dialysis treatment was performed. The properties of the obtained latex are shown in Table 2 as in Example 1. As shown in the column of adhesiveness after high humidity treatment in Table 2,
The target adhesiveness cannot be obtained without dialysis treatment.

[0036]

[Table 2] As described above, as shown by the adhesiveness after high-humidity treatment and the coating film hardness in Tables 1 and 2, it is impossible to satisfy both the adhesiveness after high-humidity treatment and the coating film hardness in any of the comparative examples. As seen in the examples of the present invention in which the adhesion under high humidity is improved while maintaining the coating film hardness, it is shown that the present invention is effective.

[0037]

INDUSTRIAL APPLICABILITY The vinylidene chloride copolymer resin latex of the present invention is applied to plastic films used for food packaging, silver halide photographic light-sensitive materials, etc., and is hard and excellent in durability, and treated with boiling water. Insulates gas and water vapor of plastic film by forming a coating film with good adhesiveness to the plastic film substrate without interposition of solvent-based adhesive layer even under conditions such as being left in a high humidity atmosphere for a long time Significantly improves the sex.

Claims (1)

[Claims] 1. A vinylidene chloride monomer of 86 to 94% by weight and a carboxyl group-containing vinyl monomer of 0.1 to 1.2.
A vinylidene chloride-based copolymer resin latex obtained by emulsion polymerization of a monomer mixture consisting of 4.8 to 13.9% by weight of one or more other vinyl-based monomers copolymerizable with them. The electrical resistivity of the latex at 25 ° C. is 2000 to 20000 Ω · m, and 170 of powder obtained by freeze-drying the latex is obtained.
A vinylidene chloride-based copolymer resin latex having a melt viscosity at 140C of 140 Pa · s or less.