JP3457062B2 - Saponified ethylene-vinyl acetate copolymer solution, aqueous dispersion and laminate - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a saponified ethylene-vinyl acetate copolymer (hereinafter abbreviated as EVOH) solution or aqueous dispersion and a laminate using the same, more specifically, it is left unheated. The present invention relates to an EVOH solution or an aqueous dispersion which is excellent in stability, transparency, gas barrier property and the like, and is also excellent in adhesiveness to a substrate, and a laminate coated with these.

[0002]

2. Description of the Related Art A film obtained from EVOH has excellent transparency and oxygen barrier property and is useful as various packaging materials for foods, medical products, industrial chemicals, etc., or as a composite material laminated with plastic film, paper or metal foil. is there. Although an EVOH film can be formed by any method, it is possible to form a film having a relatively small film thickness, and a film having a complicated shape such as a hollow container can be easily formed. The solution coating method, in which a solution of EVOH dissolved in a solvent or an aqueous dispersion of EVOH dispersed in water is applied to a substrate, has attracted attention due to the fact that it is possible to form a resin and the coating operation can be performed with a relatively simple device. ing.

In such a method, flame treatment, corona treatment, anchor coat treatment, primer treatment and the like have been conventionally performed on the surface of the base material in order to improve the adhesion to the base material. Polyurethane compounds and polyester-isocyanate compounds are preferably used as agents. However, when the above anchor coat treatment is performed, the process becomes long and the treatment agent and treatment device are required, which leads to an increase in cost. To solve this drawback, JP-A-4-8745 proposes blending a polyoxazoline compound with EVOH.

Further, when performing the solution coating method,
The storage stability and the storage stability of the EVOH solution become problems, and EVOH precipitates are deposited, which may cause disadvantages such as re-dissolution at high temperature during use. As a solution to this problem, JP-A-2-47144 discloses that boric acid is added to an EVOH solution.

Further, the applicant of the present invention also discloses in Japanese Patent Laid-Open No. 5-295119.
In the publication, it is proposed that the use of an EVOH solution having a specific melting point improves the leaving stability, the adhesion to a substrate, the transparency of a coating film, and the like. On the other hand, EVO
The aqueous dispersion of H is used as a coating liquid because it has a relatively low viscosity and does not thicken even if the EVOH concentration is high, as compared with the solution type. The coating liquid is described in, for example, JP-A-54-7874.
JP-A-54-101844 discloses a coating solution obtained by adding water and alcohol to EVOH, heating and dissolving the mixture, and then adding a surfactant to remove the alcohol.
JP-A-56-61 discloses a coating solution obtained by adding water, alcohol and a surfactant to EVOH, heating and dissolving the EVOH, and then removing the alcohol under forced high speed stirring.
In JP No. 430, a hydrophilic solvent and a surfactant are added to EVOH, and a solution obtained by heating and dissolving is emulsified and dispersed in a precipitant, and then the dispersion is aggregated at a pH of 5.5 or less, and the residue is filtered to remove the residue. Each coating liquid obtained by mixing and redispersing is disclosed.

[0006]

However, when the inventors of the present invention examined the technique disclosed in Japanese Patent Application Laid-Open No. 4-84745 in detail, the stability of the EVOH solution, especially at room temperature or higher (40 It was found that the stability of the film after being left to stand at about (° C.) and the transparency of the coating film after molding were insufficient. Further, the technique disclosed in Japanese Patent Laid-Open No. 2-47144 is EV
The purpose is to improve the stability of the OH solution, and the improvement of the adhesiveness to the substrate is not taken into consideration, and it is still insufficient.

Also in Japanese Patent Laid-Open No. 5-29119,
Use of only an EVOH solution having a specific melting point can be adopted when a polar polymer such as a polyester film is used as a base material, but when a nonpolar polymer such as a polyolefin is used as a base material, it is still more in terms of adhesiveness. It is not satisfactory, and the above thermal storage stability at about 40 ° C. is not taken into consideration.

On the other hand, regarding the aqueous dispersion type, the present inventors have made a detailed study on the matters disclosed in the above-mentioned publication, and in JP-A-54-78748, when the concentration of the dispersion is increased. There is a drawback that the viscosity becomes high, the subsequent processability, coating property, uniform film forming property, etc. deteriorate, and it is difficult to increase the concentration. In Japanese Patent Laid-Open No. 54-101844, similar to the above, there are problems such as an increase in viscosity with increasing concentration, poor leaving stability of emulsion, and poor transparency after film formation, and Japanese Laid-Open Patent Publication No. 56-61430. Also in the publication, there is a problem that the dispersion production process is complicated in addition to the increase in viscosity due to the same high concentration as described above, and there is still no satisfactory aqueous dispersion type, gas barrier property, coating film. In reality, it is expected to develop a coating solution of EVOH which is excellent in transparency and stability upon standing by heat and is also excellent in adhesiveness to a substrate such as polyolefin.

[0009]

Means for Solving the Problems As a result of intensive studies aimed at achieving the above object, the present inventors have found that the ethylene content is 60 mol% or less, the saponification degree is 90 mol% or more, and the melting point (Tm ) Satisfies the following formula (I), EVOH, an alkali (earth) metal salt or its hydroxide, and water and a carbon number of 1 to 4
It is composed of a mixed solvent of the lower alcohols mentioned above, and the blending amount of the alkali (earth) metal salt or its hydroxide is EVOH100.
0.05 to 50 parts by weight with respect to parts by weight of an EVOH solution, or the EVOH and an alkali (earth) metal salt or a hydroxide thereof, and similarly an alkali (earth) metal salt or a hydroxide thereof. The present invention has been completed by finding the fact that an EVOH aqueous dispersion having a blending amount of 0.01 to 2.5 parts by weight with respect to 100 parts by weight of EVOH can achieve the above object. -209-1.46Et + 3.31Sv <Tm <-109-1.46Et + 3.31Sv ... (I) Tm: Melting point (degreeC) by a differential scanning calorimeter Et: Ethylene content (mol%) Sv: Degree of saponification (mol%)

In the present invention, the specific melting point (T
The greatest feature is to mix an alkaline (earth) metal salt or a hydroxide thereof into an EVOH solution or an aqueous dispersion having m). With such a combination, gas barrier property, transparency of coating film, The effect of the present invention is that the heat storage stability is excellent and that the adhesiveness to the substrate is good. Hereinafter, the present invention will be specifically described.

The EVOH used in the present invention has an ethylene content of 60 mol% or less, preferably 25 to 55 mol%, more preferably 27 to 50 mol%, and a saponification degree of the vinyl acetate component of 90 mol% or more, preferably. It must be 95 mol% or more. When the ethylene content is low, the gas barrier property at high humidity tends to be lowered, while when it exceeds 60 mol%, sufficient gas barrier properties and coating properties such as printability are deteriorated. If the saponification degree is less than 90 mol%, the gas barrier property and the moisture resistance will be deteriorated.

Further, in the present invention, the melting point (Tm) determined from the peak temperature of the EVOH measured by a differential scanning calorimeter (DSC) is the ethylene content (Et mol%) and the saponification degree (Sv mol). %) EVOH in a range satisfying the following formula (I) is defined. -209-1.46Et + 3.31Sv <Tm <-109-1.46Et + 3.31Sv ... (I)

When the Tm value is smaller than the above range, the gas barrier property against oxygen and the like is deteriorated, and when the Tm value is larger than the above range, the stability of the solution or dispersion is deteriorated, and the solution or the dispersion is solidified at room temperature, or the base material is hardened. The adhesive strength is reduced and the object of the present invention cannot be achieved.
That is, as long as the Tm value of the EVOH is within the above range, the EVOH solution or aqueous dispersion obtained by combining the EVOH with an alkali (earth) metal salt or a hydroxide thereof can provide gas barrier properties, transparency and heat resistance. Excellent in leaving stability,
Moreover, the effect peculiar to the present invention that the adhesiveness to the base material such as polyolefin is excellent can be obtained. Such EVO
Other than H, the effect of the present invention cannot be obtained.

EVOH as defined in this invention is generally not commercially available. That is, ordinary E commercially available
The melting point of VOH is higher than the melting point of the present invention regardless of the ethylene content or saponification degree, and the effect of the present invention cannot be obtained by using EVOH having such a high melting point. Further, the EVOH contains a smaller amount of propylene, isobutene, α-octene, α-dodecene, α.
-Containing an α-olefin such as octadecene, an unsaturated carboxylic acid or a salt thereof, a partial alkyl ester, a complete alkyl ester, a nitrile, an amide, an anhydride, a comonomer such as an unsaturated sulfonic acid or a salt thereof as a copolymer component It doesn't matter.

In the present invention, the solvent for the EVOH is 10 to 90% by weight of water and 90 to 10% by weight of a lower alcohol having 1 to 4 carbon atoms, particularly at least one of propyl alcohol or butyl alcohol, methyl alcohol and ethyl alcohol. % Mixture is used. The amount of water is 10
-90 wt%, preferably 30-70 wt%, 1
If it is 0% by weight or less or 90% by weight or more, it is difficult to obtain a uniform solution and the coating film becomes opaque.

Examples of alcohol components such as propyl alcohol include n-propyl alcohol and iso-propyl alcohol, and examples of butyl alcohol include n-butyl alcohol, iso-butyl alcohol, sec-butyl alcohol and tert-butyl alcohol. , Iso-propyl alcohol is preferably used.

There is any method for obtaining EVOH satisfying the above Tm value, and the degree of polymerization may be controlled during the polymerization or saponification of EVOH, or the distribution of the degree of saponification may be taken into consideration. Practically, it is advantageous to treat EVOH obtained by a usual industrial production method with a peroxide or the like. Hereinafter, such a method will be described in detail.

When the ethylene content is 60 mol% or less, the saponification degree is 90 mol% or more, and the melting point (Tm) is -109- in the above formula.
Those having a melting point higher than the value calculated from 1.46Et + 3.31Sv (for example, when the ethylene content is 38 mol% and the saponification degree is 99.6 mol%, the value of the above formula is 165. 2 ° C, higher than that, eg melting point 1
73 ° C.) is dissolved in the above mixed solvent of water and lower alcohol. The concentration of the EVOH is 1 to 50% by weight,
It is preferably 10 to 40% by weight. Hydrogen peroxide (usually 35% by weight aqueous solution) was added to the solution, and EVOH / hydrogen peroxide water (35% by weight aqueous solution) = 1 / EVOH.
0.03 to 1/3 (weight ratio) is added, and the mixture is stirred at 40 to 90 ° C. for 1 to 50 hours, preferably 1 to 20.
Time to process. In some cases, metal catalysts (CuCl ₂ , CuSO ₄ , MoO ₃ and F) are used to adjust the reaction rate.
eSO ₄ , TiCl ₄ , SeO ₂ etc.) 1-5 per solution
It is preferable to add about 000 ppm, preferably about 10 to 3000 ppm. Also, water, alcohol,
The order of adding EVOH and hydrogen peroxide is not limited to the above order. Of course, it is also possible to charge the above-mentioned compounds all at once. At the end of the treatment, one point is that the viscosity of the solution at the time of start is about 10% or less of the initial viscosity.

The EVOH solution thus obtained may be blended with an alkali (earth) metal salt or a hydroxide thereof as it is to prepare the EVOH solution of the present invention, but preferably an enzyme such as catalase is added and left. It is better to decompose and remove hydrogen peroxide. The method for removing the residual hydrogen peroxide is not limited to the above method, and a known removal method can be adopted as long as the effect of the present invention is not impaired. Alternatively, the solution may be replaced with a solvent and dissolved in a mixed solvent of water and alcohol specified in the present invention to prepare an arbitrary solution.
Alternatively, the desired solid EVOH can be obtained by removing the solvent of water and alcohol from the solution by a known method using a fluidized bed dryer, a gas stream dryer, a freeze dryer or the like.

In order to obtain the EVOH aqueous dispersion of the present invention, the solid EVOH obtained as described above is dispersed in water to obtain an aqueous dispersion. In the present invention, however,
The method for producing the dispersion is not limited, and the methods described in JP-A-54-78748 and JP-A-54-101844 are not limited.
JP-A-56-61430, JP-A 5-1
Although conventionally known methods such as JP-A-799001 are appropriately adopted, JP-A-5-179001 which uses a centrifugal separation method from the viewpoints of obtaining fine particles and the easiness of concentration operation, etc.
The method according to the publication is particularly preferred.

That is, (1) a step of heating and dissolving the above-mentioned hydrogen peroxide-treated EVOH in a mixed solvent of alcohol having 1 to 4 carbon atoms and water, and (2) cooling the obtained solution to obtain the EVOH. Precipitation step, (3) precipitated EVOH
A step of concentrating the dispersion liquid containing
(4) a step of adding an aliphatic ketone and a dispersion stabilizer to the obtained concentrated solution to obtain a stable dispersion; and (5) a step of removing the aliphatic ketone and alcohol from the obtained dispersion, The method for producing an aqueous dispersion remarkably exhibits the effects of the present invention. A more specific manufacturing method is as follows.

The alcohol used in step (1) has 1 to 4 carbon atoms, and is methyl alcohol, ethyl alcohol, n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, iso-butyl alcohol, t. Examples thereof include one or more mixed alcohols such as butyl alcohol, and industrially, methyl alcohol and iso-propyl alcohol are preferable from the viewpoints of cost and removability.

The mixing ratio of water and alcohol is not particularly limited, but the weight ratio of water / alcohol = 9/1 to 1/9 is preferable, and water / alcohol = 7/3 to 3 is more preferable.
/ 7. If the mixing ratio is out of this range, the solubility of EVOH decreases, so that it becomes difficult to prepare a homogeneous EVOH solution, and a dispersion of good quality cannot be obtained. A preferable range of the melting temperature is 50 to 120 ° C. The amount of EVOH with respect to the water-alcohol mixed solvent is 50 to 12
Solubility at 0 ° C can be added. At this time, the EVOH concentration is 1% by weight or more and less than 20% by weight, which takes into consideration the solubility in a water-alcohol mixed solvent and the stability of the solution, and is preferably 1 to 15% by weight.

The EVOH solution is prepared according to known procedures. That is, EV is added to the above water-alcohol mixed solvent.
OH mixed, turbine type under heating at 50-120 ° C,
Rotation speed 1 using a stirrer equipped with a ribbon type stirring blade
Mix and stir under the condition of 0 to 1000 rpm to prepare a solution of EVOH.

Step (2) The EVOH solution obtained in Step (1) is cooled and EVOH
Precipitate fine particles to form a dispersion. That is, step (1)
By lowering the temperature of the EVOH solution (above the critical melting temperature of EVOH) to below the critical melting temperature of EVOH, EVOH fine particles are deposited by utilizing the difference in solubility due to the temperature difference. The cooling temperature of this process is EVOH
Considering the precipitation effect of fine particles, it is usually preferable to set the temperature to 40 ° C. or lower.

[0026]Process (3) What is the centrifugal separation method used in this process?
Separation of two liquid phases or liquid and solid phases by the difference of
This is a method using a normal centrifuge. Immediately
The amount of EVOH fine particles deposited by cooling in step (2)
Disperse the liquid with a screw decanter type or cylindrical type.
Solid-liquid separation is performed by a cardiac sedimentation separator and the supernatant is removed to EV
An OH concentrate is obtained. EVOH concentration after this concentration
20% by weight or more is essential, and if less than 20% by weight,
It takes time to remove alcohol in (5) and also has stability
descend. The upper limit is not particularly limited, but this work
About 40% by weight was
It is the limit. A preferred range is 20 to 35% by weight.

Step (4) Aliphatic ketone is added to the EVOH concentrate obtained in Step (3).
A dispersion stabilizer is added to stabilize the dispersion of EVOH fine particles in the concentrated liquid. That is, the aliphatic ketone remains as an anti-agglomeration agent, thereby preventing alcohol swelling of the EVOH fine particles, and the dispersion stabilizer is effective for imparting surface activity and protective colloidal property, and secondary aggregation and blocking of the fine particles ( Gelation), and it is possible to produce a dispersion liquid of EVOH having stable dispersibility.

As the aliphatic ketone used in this step, acetone and methyl ethyl ketone are preferably used. The amount used is 100 to 200 with respect to 100 parts by weight of EVOH.
0 weight part is preferable, More preferably, it is 250-1500.
Parts by weight. When the amount of the aliphatic ketone added exceeds the above range, it takes time to remove the solvent in the step (5), and when it is less, the stability of the EVOH dispersion liquid deteriorates.

Usual anionic and nonionic surfactants are used as the dispersion stabilizer, and specific examples of the anionic surfactant include sodium vinyl sulfonate, sodium dodecylbenzene sulfonate, sodium lauryl sulfonate and the like. As the nonionic type, there are polyoxyethylene type polyoxyethylene lauryl ether, polyoxyethylene nonylphenol ether, polyoxyethylene sorbitan monooleate, polyoxypropylene type and polyoxyethylene-polyoxypropylene copolymer type. . The amount of the surfactant used is preferably in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of EVOH as an amount that can be emulsified and dispersed and does not impair the characteristics of the coating film of the EVOH dispersion.

It is also advantageous to use a protective colloid agent as a dispersion stabilizer, and polyvinyl alcohol, partially saponified polyvinyl alcohol, polyvinyl alcohol derivatives, modified polyvinyl alcohol, cellulose derivatives such as hydroxyethyl cellulose and hydroxypropyl cellulose, poly Examples thereof include sodium acrylate, polyacrylic acid amide, polyvinylpyrrolidone and the like. The amount used is preferably in the range of 0.1 to 10 parts by weight based on 100 parts by weight of EVOH for the same reason as for the surfactant. The surfactant and protective colloid agent are preferably added as an aqueous solution of 1 to 20% by weight.

The aliphatic ketone and the dispersion stabilizer may be added to the EVOH concentrate with stirring, and any stirrer may be used. The order of addition is not particularly limited, but it is more efficient to add the aliphatic ketone first and then add the dispersion stabilizer, so that the dispersion liquid can be formed. In this step, since a considerably large amount of aliphatic ketone and water as a dispersion stabilizer solvent are systematically added, the concentration of the concentrated EVOH dispersion liquid once drops, but both step (3) and this step are final. It is essential to obtain a stable aqueous dispersion.

Also in this step, if necessary, it is possible to add an anti-blocking agent or a film-forming auxiliary agent in order to prevent sticking when a film is formed. In this case, examples of the anti-blocking agent include inorganic powders such as silica and talc, and examples of the film forming aid include polyhydric alcohols such as ethylene glycol, propylene glycol and glycerin. The usage is EVOH1
0.01 to 10 parts by weight of the inorganic powder with respect to 00 parts by weight,
The film-forming aid is appropriately selected from the range of 5 to 100 parts by weight.

Step (5) An aqueous dispersion having an EVOH concentration of 5 to 50% by weight, preferably 10 to 40% by weight, in which a solvent such as an aliphatic ketone and an alcohol is removed from the above EVOH dispersion and water is used as a main component of the medium. Get the liquid. That is, the EVOH dispersion is stirred under reduced pressure (30 to 100 mmHg) and / or under heating (40
To 80 ° C.), all or part of the aliphatic ketone and alcohol in the dispersion is removed to reduce the alcohol content in the aqueous medium to 5% by weight or less. Further, it is desirable to remove all of the aliphatic ketone, but even if a small amount remains, the effect of the present invention is not impaired.

In the present invention, the EVOH obtained as described above
An alkali (earth) metal salt or its hydroxide is added to the solution or EVOH aqueous dispersion. The alkali (earth) metal salts or hydroxides thereof include hydroxides such as sodium hydroxide and potassium hydroxide, acetates such as sodium acetate, potassium acetate, calcium acetate and magnesium acetate, sodium sulfate and potassium sulfate. Examples thereof include sulfates such as magnesium sulfate, carbonates such as sodium carbonate and potassium carbonate, hydrogencarbonates such as magnesium hydrogencarbonate and hydrogensulfate, and preferably sodium hydroxide, potassium hydroxide, sodium acetate, potassium acetate. Etc. are used.

The amount of the alkali (earth) metal salt or its hydroxide compounded is 0.01 to 100 parts by weight of EVOH.
It is 2 parts by weight, preferably 0.05 to 2 parts by weight. If the amount of the alkali (earth) metal salt or its hydroxide compounded is less than 0.01 parts by weight, the adhesive strength will be insufficient, while 2
If the amount is more than the amount by weight, the transparency and gas barrier property of the produced film deteriorate, and the effect of the present invention cannot be obtained. Further, in the case of the EVOH solution, a mixed solvent of water and a lower alcohol having 1 to 4 carbon atoms is also blended as described above.
The order of mixing H, an alkali (earth) metal salt or a hydroxide thereof, and the mixed solvent is not particularly limited, and batch charging is performed or an alkali (earth) metal salt or a water thereof is added to a solution in which EVOH is dissolved in a mixed solvent. An oxide is added, EVOH is added later, or the like is appropriately selected.

Further, in the present invention, in the case of the EVOH solution, in addition to the alkali (earth) metal salt or its hydroxide and the mixed solvent, trimethylolpropane, triphenylmethane triisocyanate, ethylene diisocyanate, 1,4 -Butane diisocyanate, 1,6-hexane diisocyanate, dicyclohexylmethane diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, 2,4- and 2,6-
Isocyanate compounds such as tolylene diisocyanate, methylene diphenyl diisocyanate, diphenyl methane-4,4'-diisocyanate and xylene diisocyanate; monoaldehydes such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, glyoxylic acid; glyoxal, malondialdehyde, succindi Aldehyde, glutardialdehyde,
Dialdehydes such as maleindialdehyde and phthalaldehyde; polyhydric aldehydes such as starch; diamines such as hexamethylenetetramine, ethylenediamine, trimethylenediaminephenylenediamine; N-methylolurea, dimethylolurea, alkylated methylolurea, N
Methylol compounds such as methylol melanin and alkylated methylol melanin; epoxy compounds such as epichlorohydrin, propylene oxide, styrene oxide, cyclohexene oxide, cyclopentene oxide; oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid,
At least one selected from dicarboxylic acids such as maleic acid, fumaric acid and phthalic acid can be blended in an amount of about 0.1 to 20% by weight, and the effect of the present invention is exhibited.

The EVOH solution or aqueous dispersion of the present invention thus obtained is applied to a substrate.
The EVOH concentration in the OH solution or the aqueous dispersion is not particularly limited, but in consideration of the coating property on various substrates and the stability of standing, etc., 1 to 50% by weight, preferably 10 to 40% by weight, It is preferably about 20 to 30% by weight.

In the present invention, the substrate to which the EVOH is applied is not particularly limited, and a stretched or unstretched film, sheet, hollow container or paper of various plastics such as polyethylene, polypropylene, polyester, polystyrene, polyvinyl chloride, nylon, etc. , Cellophane, cellulose, cellulose acetate, natural rubber, synthetic rubber,
Examples include metals. The thickness of the base material is 10 to 100.
About 0 μ is suitable.

In the present invention, the EVOH coating film and the substrate can be firmly adhered to each other without applying the anchor coating treatment to the substrate during the coating as in the prior art. As a coating method at this time, a roller coating method such as a Meyer bar, a gravure and a reverse roll method, a spray coating method, a dip coating method or any other known method can be applied. Then, after coating the substrate with the EVOH solution or the aqueous dispersion, drying is performed by a known method. For example, in the case of EVOH solution, the drying temperature is 3
It may be heated at a temperature of 0 to 150 ° C., preferably 70 to 120 ° C. for about 3 seconds to 5 minutes, and the EVOH aqueous dispersion may be heated under the same conditions. Although the volatile components in the coating film, that is, water and alcohol, are removed by such drying, it is usually performed until the volatile components become 2% by weight or less.

Thus, a transparent coating film of EVOH is formed, and the film thickness is practically about 0.5 to 500 μm, preferably about 1 to 100 μm. If it is less than 0.5μ, it is difficult to exhibit sufficient gas barrier properties, while 500
If it is more than μ, it becomes difficult to control the film thickness.
It is also possible to form a moisture-proof layer on the coating film, if necessary, by coating a vinylidene chloride resin, a vinyl chloride-vinyl acetate copolymer, or the like. The formed coating film of the EVOH solution or the aqueous dispersion of the present invention has excellent adhesiveness to various substrates, and it is of course possible to apply it without an anchor coat, but further improvement in adhesiveness is possible. For the purpose, an anchor coating agent such as polyurethane, polyester or polyethyleneimine may be used in combination.

A laminate obtained by coating various substrates with an EVOH solution or an aqueous dispersion is used for packaging foods, beverages, medicines, medicines, electrical parts, machine parts, etc. or containers, heating pipes, wallpaper, etc. It is useful for various purposes. As a packaging material having a high practicability and a layer structure of a container, a substrate (polyester, polyethylene, etc.) having a film thickness of 10 to 1000 μ / EVOH having a film thickness of 0.5 to 500 μ (volatile content of 0.5 to 5) is typically used. % By weight) or on the EVOH layer having the above structure, a vinylidene chloride resin layer or a vinyl chloride-vinyl acetate copolymer layer having a film thickness of about 0.5 to 3 μm is further provided. The shape may be any shape such as a film shape, a sheet shape, a hollow bottle and a tube.

[0042]

INDUSTRIAL APPLICABILITY The present invention is an EVOH solution or an aqueous dispersion containing EVOH having a specific melting point and an alkali (earth) metal salt or its hydroxide. In addition to being excellent in transparency and gas barrier property, it is also extremely excellent in adhesiveness to various base materials such as polyolefin, and laminated with various base materials, for example, food / pharmaceutical packaging, containers, etc. It can also be used as an interior material for construction such as or wallpaper, or as a furniture or interior material for automobiles by coating vinyl leather or the like.

[0043]

EXAMPLES The present invention will be specifically described below with reference to examples. In the examples, "part" and "%" are based on weight unless otherwise specified. Examples 1 to 3 30 parts of EVOH (ethylene content 30 mol%, saponification degree 99.5 mol%, melting point 187 ° C.) was added to a mixed solvent of 22 parts of water and 35 parts of alcohol and added at 70 to 80 ° C. to about 2 Stir for hours to prepare a clear solution. Next, 13 parts of hydrogen peroxide solution (35% aqueous solution) and 50 parts of iron sulfate heptahydrate were added to the solution.
ppm was added and reacted at 80 ° C for about 5 hours under stirring, then cooled to 40 ° C, and further 3000 ppm of catalase.
To remove the residual hydrogen peroxide, and finally prepare a 20% EVOH solution, to which an alkali (earth) metal salt or its hydroxide as shown in Table 2 is added. To obtain an EVOH solution of the present invention. E in the EVOH solution
VOH has an ethylene content of 30 mol% and a saponification degree of 99.
6 mol%, melting point Tm measured by DSC 1
It was 48 ° C. This Tm value is 77 ° C <Tm specified in the present application.
It was <177 ° C.

Then, the corona-treated surface of the stretched polypropylene film (thickness 20 μ) was coated with the EVOH solution by an applicator coating method, and the temperature was raised to 100 ° C.
Was dried for 3 minutes to obtain a laminate having a dry film thickness of EVOH of 3μ. The following physical properties of the EVOH solution thus obtained and the laminate thereof were measured.

(Stability upon leaving) 10 EVOH solution obtained
0 ml was transferred to a 100 ml graduated cylinder, and the amount of the separated transparent liquid after 2 weeks was measured at 40 ° C. The evaluation criteria are as follows. ○ --- No generation of separation transparent liquid △ --- Generation of separation transparent liquid of less than 10 ml × --- Generation of separation transparent liquid of 10 ml or more (transparency) The haze value (%) of the laminate was measured with a haze meter.

(Interlayer Adhesion) Cellophane tape was adhered to the EVOH surface of the laminate, and the cellophane tape and polypropylene film were pulled at a pulling speed of 300 mm / min to measure the adhesive force (g / 15 mm). (Oxygen barrier property) Oxygen permeability of laminated body (cc / m ² · atm · 24
hr) was measured at 20 ° C. and 65% RH.

Examples 4 to 6 The same as in Example 1 except that EVOH (raw material) having an ethylene content of 30 mol%, a saponification degree of 99.6 mol% and a melting point of 188 ° C. was used and the reaction time was 4 hours. 20% E
A VOH solution was prepared, and then each amount of an alkali (earth) metal salt or its hydroxide as shown in Table 2 was added to obtain an EVOH solution of the present invention and a laminate thereof. The obtained EVO
The same measurement as in Example 1 was performed on the H solution and the laminate. The ethylene content of EVOH in the EVOH solution was 30 mol%, the saponification degree was 99.5 mol%, and the melting point was T.
When m was measured by DSC, it was 148 ° C. This T
The m value satisfied 77 ° C <Tm <177 ° C specified in the present application.

Comparative Example 1 Commercially available EVOH (ethylene content 30 mol%, saponification degree 99.5 mol%, melting point 188 ° C., 77 as in Example 1)
℃ <Tm <177 ℃, the melting point is outside the specification of the present application) 20 parts to water 40 parts, alcohol 40 parts, 70
Stir for about 2 hours at ~ 80 ° C, clear EV with 20% concentration
Prepare OH solution and add sodium hydroxide to EVOH
1 part by weight was added to 100 parts by weight to obtain an EVOH solution and a laminate thereof. The same measurement as in Example 1 was performed on the obtained EVOH solution and the laminate.

Comparative Examples 2 and 3 In Example 1, sodium hydroxide was added to EVOH100.
EVOH was added in the same manner except that 0.005 parts by weight (Comparative Example 2) or 3 parts by weight (Comparative Example 3) was added to the parts by weight.
A solution and its laminate were obtained. The same measurement as in Example 1 was performed on the obtained EVOH solution and the laminate.

Comparative Example 4 In Example 1, 30 parts of EVOH (ethylene content 30 mol%, saponification degree 99.6 mol%, melting point 188 ° C.),
Alcohol 35 parts (water 0 part), hydrogen peroxide water (35% aqueous solution) 35 parts, and the same procedure except that iron sulfate heptahydrate was not added, EV with 20% concentration with Tm value of 188 ° C.
An OH solution was obtained. The Tm value is 77 ° C <T defined in the present application.
It is outside the range of m <177 ° C. Sodium hydroxide was added to the EVOH solution in an amount of 1 part by weight based on 100 parts by weight of EVOH to obtain an EVOH solution and a laminate thereof. Obtained E
The same measurement as in Example 1 was performed on the VOH solution and the laminate.

Comparative Example 5 In Example 1, 30 parts of EVOH (ethylene content 30 mol%, saponification degree 99.5 mol%, melting point 187 ° C.),
Alcohol 35 parts (water 0 part), hydrogen peroxide solution (35% aqueous solution) 35 parts, iron sulfate heptahydrate 3000 ppm, reaction time was 15 hours. EVOH solution was obtained. The Tm value is outside the range of 77 ° C <Tm <177 ° C specified in the present application. The EV
1 part by weight of sodium hydroxide was added to 100 parts by weight of EVOH in the OH solution to obtain an EVOH solution and a laminate thereof. The same measurement as in Example 1 was performed on the obtained EVOH solution and the laminate.

Example 7 To a mixed solvent of 22 parts of water and 35 parts of alcohol, 30 parts of EVOH (ethylene content 30 mol%, saponification degree 99.5 mol%, melting point 187 ° C.) was added and the mixture was heated to about 70 ° -80 ° C. Stir for 2 hours to prepare a clear solution. Next, 13 parts of hydrogen peroxide solution (35% aqueous solution) and 50 parts of iron sulfate heptahydrate were added to the solution.
After adding ppm and reacting at 80 ° C for about 4 hours under stirring, the mixture was cooled to 40 ° C and further catalase was added to 3000 ppm.
30% by removing residual hydrogen peroxide
EVOH solution was obtained. The EVOH solution was heated at 100 ° C. for 9
It was dried under the condition of 0 minutes to obtain solid EVOH. The EV
The ethylene content of EVOH in the OH solution is 30 mol%,
The saponification degree was 99.5 mol%, and the melting point Tm was 148 ° C. as measured by DSC. This Tm value satisfied 77 ° C <Tm <177 ° C specified in the present application.

For the preparation of the aqueous dispersion of EVOH,
The following steps (1) to (5) were performed. Step (1) Iso-propyl alcohol 45 was added to 10 parts of the above EVOH.
And 45 parts of water were added and mixed and stirred for about 2 hours at a rotation speed of 500 rpm and a heating state of 80 ° C. with a stirrer of a turbine type stirring blade to prepare a 10% EVOH water-alcohol solution. Step (2) The EVOH solution of step (1) was allowed to stand in a thermostat at 5 ° C. for 24 hours to precipitate EVOH fine particles to obtain a fine particle dispersion.

Step (3) After returning the dispersion liquid to room temperature, it was transferred to a centrifuge and centrifuged for 30 minutes at a rotation speed of 7,000 rpm, and then the supernatant was removed to obtain 40 parts of 25% EVOH concentrate. Got Step (4) Next, 50 parts of acetone was added to the concentrated solution, and the mixture was stirred for about 5 minutes with the same stirrer as in step (1). Thereafter, 0.5 part of a surfactant (sodium laurylate) and 0.2 part of a protective colloid agent (partially saponified polyvinyl alcohol having a polymerization degree of 500 and a saponification degree of 88 mol%) are added, and the mixture is further stirred for 20 minutes. A stable EVOH dispersion was obtained. The surfactant and the protective colloid agent were each used as a 5% aqueous solution.

Step (5) The EVOH dispersion liquid obtained in the step (4) was transferred to an evaporator, and while being heated to 60 ° C., the pressure was gradually reduced to 30 m.
Solvent removal in the dispersion was performed at mHg for about 2 hours. Thereafter, water was added to adjust the concentration to obtain an EVOH aqueous dispersion having a concentration of 20%. The content of iso-propyl alcohol in the aqueous dispersion was 3% in the aqueous medium, and the content of acetone was 0.

Further, 0.2 part by weight of sodium hydroxide (EVOH100) is added to 100 parts by weight of the EVOH aqueous dispersion.
1 part by weight to 1 part by weight) of EVOH of the present invention
An aqueous dispersion was obtained. Further, a laminate was prepared in the same manner as in Example 1, and various physical properties of the obtained EVOH aqueous dispersion and the laminate were measured in the same manner as in Example 1. Examples 8 to 12 Table 1 is the same as Example 7 except that EVOH (raw material) shown in Table 1 was used and the hydrogen peroxide solution treatment time was 20 hours.
An EVOH of the present invention having a Tm value shown in Table 1 was obtained. Next, according to Example 7, an EVOH aqueous dispersion having the composition shown in Table 2 was obtained, and a laminate thereof was further prepared. These E
The same measurement as in Example 1 was performed on the VOH aqueous dispersion and its laminate.

Comparative Example 6 Commercially available EVOH (ethylene content 30 mol%, saponification degree 99.5 mol%, melting point 187 ° C., 77 as in Example 1)
(° C <Tm <177 ° C., melting point is outside the regulation of the present application) 22 parts of water and 35 parts of alcohol were added to 30 parts to obtain an EVOH aqueous dispersion and its laminate in the same manner as in Example 7. The same measurement as in Example 1 was performed on the obtained EVOH aqueous dispersion and its laminate.

Comparative Examples 7 and 8 In Example 7, the blending amount of sodium hydroxide was changed to EVO.
0.005 parts by weight to 100 parts by weight of H (Comparative Example 7)
Alternatively, an EVOH aqueous dispersion and a laminate thereof were obtained in the same manner as in Example 7 except that 3 parts by weight (Comparative Example 8) was used, and each was evaluated.

Comparative Example 9 In Example 7, 30 parts of EVOH (ethylene content 30 mol%, saponification degree 99.5 mol%, melting point 188 ° C.),
Hydrogen peroxide solution (35% aqueous solution) 13 parts, iron sulfate-7
The Tm value was 18 except that the hydrate was not added.
EVOH at 8 ° C. was obtained. The Tm value is 77 as defined in the present application.
It is outside the range of ° C <Tm <177 ° C. Furthermore, the EVOH
An aqueous dispersion (1 part by weight of sodium hydroxide based on 100 parts by weight of EVOH) was prepared in the same manner as in Example 7, and a laminate was prepared. The same measurement as in Example 1 was performed on the obtained EVOH aqueous dispersion and its laminate.

Comparative Example 10 In Example 7, hydrogen peroxide solution (35%) was added without adding water.
% Aqueous solution), iron sulfate heptahydrate 3000 pp
m and the reaction time was 10 hours.
EVOH having an m value of 65 ° C. was obtained. The Tm value is outside the range of 77 ° C <Tm <177 ° C specified in the present application. Furthermore, the E
An aqueous dispersion of VOH was prepared in the same manner as in Example 7, and a laminate thereof was prepared. The same measurement as in Example 1 was performed on the obtained EVOH aqueous dispersion and its laminate. Table 2 shows the measurement results of Examples and Comparative Examples.

[0061]

[Table 1] EVOH (raw material) EVOH Tm value range after reaction Et Sv Melting point (° C) Tm value Examples 1-3 30 99.5 187 148 77 <Tm <177 〃 4-6 30 99.6 188 148 77 <Tm <177 〃 7 30 99.5 187 148 77 <Tm <177 〃 8 to 12 30 99.9 188 146 78 <Tm <178 Comparative Example 1 to 30 30 99.5 187 187 77 <Tm <177 〃 4 30 99.6 188 188 77 <Tm < 177 〃 5 30 99.5 187 60 77 <Tm <177 〃 6 to 8 30 99.5 187 187 77 <Tm <177 〃 9 30 99.5 188 188 77 <Tm <177 〃 10 30 99.5 187 65 77 <Tm <177 Note) Et : Ethylene content (mol%) Sv: saponification degree (mol%) Tm: melting point by DSC (° C)

[0062]

[Table 2] Alkali (earth) metal salt Aged interlayer Transparency Oxygen permeability or its hydroxide stability Adhesive strength (compound / part by weight) (g / 15mm) (%) (cc / m ² · atm・ 24 hr) Example 1 A ・ 0.01 ○ 250 2.2 4.6 〃 2 A ・ 1.0 ○> 300 2.2 4.4 〃 3 A ・ 2.0 ○> 300 2.2 4. 6 〃 4 B ・ 0.05 ○> 300 2.1 4.5 〃 5 C ・ 2.0 ○> 300 1.9 4.7 〃 6 D ・ 1.0 ○> 300 2.1 4.8 〃 7 A ・ 0.02 ○> 300 2.0 4.5 〃 8 A ・ 0.01 ○ 250 2.1 4.8 〃 9 A ・ 1.0 ○> 300 2.3 4.6 〃 10 B ・0.05 ○> 300 2.1 4.5 〃 11 B ・ 1.0 ○> 300 2.3 4.5 〃 12 C ・ 1.0 ○> 300 2.3 4.7 Comparative Example 1 No additive × 5 2.0 2.8 〃 2 A ・ 0.005 × 5 2.1 2.8 〃 3 A ・0.0 x 5 3.7 4.1 〃 4 A ・ 2.0 × 10 2.1 5.1 〃 5 A ・ 2.0 〇> 300 5.2 42 〃 6 A ・ 0.2 × 5 2. 0 3.1 〃 7 A ・ 0.005 × 5 1.9 2.9 〃 8 A ・ 3.0 × 5 3.1 5.0 〃 9 A ・ 0.01 × 5 2.5 3.2 〃 10 A · 0.2 ○> 300 6.2 86 Note) The blending amount of the alkali (earth) metal salt or its hydroxide is the blending amount based on 100 parts by weight of EVOH. Street. A: sodium hydroxide, B: potassium hydroxide, C: sodium acetate, D: potassium acetate

[0063]

INDUSTRIAL APPLICABILITY The present invention is an EV comprising EVOH having a specific melting point and an alkali (earth) metal salt or its hydroxide.
Since it is an OH solution or an aqueous dispersion, it is excellent in stability under heat for a long time, transparency of coating film, gas barrier property, and also excellent in adhesion to various substrates such as polyolefin. It is used as an interior material for buildings such as food / pharmaceutical packaging, containers and laminates, wallpaper, etc., or PVC leather by coating it with various base materials. You can also do it.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ identification code FI C09D 129/04 C09D 129/04 (58) Fields investigated (Int.Cl. ⁷ , DB name) C08L 23 / 00-23 / 36 C09D 123/00-123/36 C08L 29/00-29/14 C09D 129/00-129/14

Claims (4)

(57) [Claims] 1. A saponified ethylene-vinyl acetate copolymer having an ethylene content of 60 mol% or less, a saponification degree of 90 mol% or more, and a melting point (Tm) satisfying the following formula (I): an alkali. (Earth) consisting of a metal salt or hydroxide thereof and a mixed solvent of water and a lower alcohol having 1 to 4 carbon atoms,
The amount of the alkali (earth) metal salt or its hydroxide compounded is 0.01 to 2.5 parts by weight based on 100 parts by weight of the saponified ethylene-vinyl acetate copolymer ethylene. Saponified vinyl acetate copolymer solution. -209-1.46Et + 3.31Sv <Tm <-109-1.46Et + 3.31Sv ... (I) Tm: Melting point (degreeC) by a differential scanning calorimeter Et: Ethylene content (mol%) Sv: Degree of saponification (mol%) 2. An ethylene-vinyl acetate copolymer saponification product and an alkali having an ethylene content of 60 mol% or less, a saponification degree of 90 mol% or more, and a melting point (Tm) satisfying the following formula (I): (Earth) metal salt or its hydroxide, and the blending amount of alkali (earth) metal salt or its hydroxide is 0.01 to 100 parts by weight of saponified ethylene-vinyl acetate copolymer. 2.5 parts by weight of an aqueous dispersion of saponified ethylene-vinyl acetate copolymer. -209-1.46Et + 3.31Sv <Tm <-109-1.46Et + 3.31Sv ... (I) Tm: Melting point (degreeC) by a differential scanning calorimeter Et: Ethylene content (mol%) Sv: Degree of saponification (mol%) 3. The solution of saponified ethylene-vinyl acetate copolymer according to claim 1 or 2, wherein the solid concentration of EVOH in the solution or aqueous dispersion is 5 to 50% by weight. Dispersion. 4. A laminate comprising a base material coated with the saponified ethylene-vinyl acetate copolymer solution or aqueous dispersion according to claim 1.