JPS5827815B2 - Method for producing surface-treated vinyl alcohol polymer film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a vinyl alcohol polymer film surface-treated with a fluororesin.

Vinyl alcohol polymer films such as polyvinyl alcohol films have poor slip properties as they are, and they tend to block when stacked or rolled up. Therefore, it is necessary to attach fine inorganic or organic powder to the film surface. However, if a sufficient amount of fine powder is attached to improve slip properties and anti-blocking properties, there is a problem in that heat sealing properties and adhesive sealing properties are impaired, and the attached fine powder There is also the problem that it easily falls off.

In addition, a method of coating with polystyrene emulsion instead of fine powder has recently been proposed, but the effect of improving slip property and blocking resistance is not necessarily sufficient, and furthermore, the excellent gloss and transparency of polyvinyl alcohol film are reduced. There is a fear that

The present invention completely solves the above-mentioned conventional problems, and the surface-treated vinyl alcohol polymer film is coated with an aqueous dispersion or solution of fluororesin on the surface of the vinyl alcohol polymer film and dried. It is characterized by producing a combined film.

When the surface of the film treated in this manner is observed under an electron microscope, it can be seen that fluororesin particles are randomly scattered.

When a fluororesin dispersion is used, spherical particles are scattered on the surface of the film, either individually or in groups of several to ten or more.

The same applies to the case where a fluororesin solution is used.

This seems to be because even though the fluororesin appears to be completely dissolved in the organic solvent, it is actually suspended in the organic solvent as fine particles.

The fact that the fluororesin particles are scattered on the film surface gives the film various properties.

And the coverage rate of the film surface with fluororesin is 0.5
It is desirable to be in Section 2.

This value is considerably smaller than the coverage rate in conventional inorganic fine powder coating methods.

In addition, in the case of aqueous dispersion coating, the average diameter of the fluororesin in the aqueous dispersion is 0.08 to 0.8μ, especially 0.1 to 0.6μ, and even after coating and drying, the particle size is approximately this size. The particle size is maintained, which is considerably smaller than the average particle size of normal inorganic fine powders and spherical.

In this regard, JP-A-51-1.34766 and JP-A-51-13
No. 4767, No. 138770, No. 51-1, No. 13877, No. 51-1
No. 38771, No. 139867, No. 139867, No. 51-
In the 139868 Aoyo Publication, the particle size is 1 to 100μ as a fine powder to be sprinkled on a polyvinyl alcohol film.
In particular, particles with a particle size of 5 to 20 microns are used, and it is said that particles with a particle size of 1 micron or less have little adhesion prevention effect.

Among ordinary inorganic fine powders, some primary particles have the same particle size as the fluororesin of the present invention, but on the actual film surface, they aggregate with each other and form blocks of about 3μ. many.

These differences, combined with the specific material of the fluororesin particles, provide extremely favorable results for surface treatment of vinyl alcohol polymer films.

That is, the present invention has the following excellent effects.

(1) High slip property, static friction coefficient 20°C18
At 0% RH, the static friction coefficient is, for example, 0.40, which is significantly superior to the static friction coefficient of commercially available equivalent products, which is, for example, around 0.8.

This property means that the winding of the film proceeds smoothly, the winding appearance is beautiful, and it is easy to align the bags during bag making, making it practical.
- This is a big advantage.

(2) Excellent blocking resistance.

Even if a large number of films or bags are stacked or the films are wound on a winder, blocking will not occur between the films.

Shows sufficient blocking resistance even at high temperatures and high humidity.

(3) Does not impair heat sealability.

Even with ordinary commercially available products, if the amount of fine powder sprayed or coated is increased, the slip properties and anti-blocking properties will be improved accordingly, but the heat seal properties will be drastically reduced and the product will eventually lose its practicality.

However, in the present invention, even if the coverage is small, the heat sealability is hardly impaired, although the slip properties and anti-blocking properties are significantly improved as described above.

(4) Does not impair adhesive sealing properties.

For the same reason as stated in (3) above, in the present invention, the sealing performance by glue is hardly impaired.

(5) Pass the printing test.

Even if the treated film of the present invention is printed using vinylon ink and the printed film is subjected to a peel test with an adhesive tape, a kneading test, and a scratch test,
The printed surface will not fall off or become unclear.

This is probably due to the fact that the present invention has a small coverage of the fluororesin, has a small particle size and is spherical, and has good adhesion to the film, making it able to withstand the above tests.

(6) Transparency and gloss are not impaired.

Even with the fluororesin treatment of the present invention, compared to untreated products,
Transparency and gloss remain almost unchanged.

The vinyl alcohol polymer in the present invention refers to a partial or complete saponified product of a vinyl ester polymer or copolymer, or a subsequently modified product.

Examples include (a) polyvinyl alcohol obtained by saponifying polyvinyl acetate with a molar ratio of about 50 to 100; (b) monomers that are mainly vinyl acetate and copolymerizable with it, such as olefins (ethylene, propylene, α Butene, α-
octene, α-dodecene, α-occudecene, etc.), unsaturated monocarboxylic acids (acrylic acid, methacrylic acid, crotonic acid, etc.) or their esters or salts, unsaturated polycarboxylic acids (maleic acid, fumaric acid, itaconic acid, etc.) etc.) or their partial or complete esters or salts or anhydrides), unsaturated sulfonic acids (ethylene sulfonic acid, allyl sulfonic acid, mequalyl sulfonic acid, etc.) or their salts, amides (acrylamide, methacrylamide, etc.)
, copolymers with nitrile (acrylonitrile, meccrylonitrile, etc.), vinyl ether, vinyl ketone, vinyl chloride, etc., in which part or all of the vinyl acetate component is saponified (the proportion of other copolymerizable monomers is 50
The ethylene content may be less than or equal to 20 molar, particularly F0 or less, but when ethylene is used as the comonomer, the ethylene content may be up to about 95 molar.

), (c) above (a), (b) f acecooling, urethanization, phosphoric acid esterification, cyanoethylation, or modified products after grafting a vinyl monomer.

Such vinyl alcohol polymer films include not only flat films, but also cylindrical films and sheets, as well as hollow fibrous materials, bottle-shaped or box-shaped containers, and the like.

These films may be subjected to heat treatment, -axial or biaxial stretching treatment, lamination treatment with other substrates, etc.

Fluororesins include polytetrafluoroethylene, polychlorotrifluoroethylene, tetrafluoroethylene-hexafluorobutylene pyrene copolymer, polyvinylidene fluoride, polyvinyl fluoride, etc., but the first three are particularly preferred. Al in polytetrafluoroethylene.

The fluororesin is applied in the form of a dispersion or a solution, but the form of a dispersion is superior to that of a solution (organic or inorganic solvent solution) in terms of the effects of imparting slip properties and anti-blocking properties.

The medium of the dispersion is usually water, but even if an organic solvent is contained there is no particular problem except for contamination of the working environment due to volatilization.

Now, in the case of an aqueous dispersion, the average particle size of the fluororesin is 0.08
It is desirable to select from the range of 0.1 to 0.6 μ, especially 0.1 to 0.6 μ.

If the average particle size is too small, it is not only difficult to manufacture, but also
On the contrary, the slip properties and anti-blocking properties become insufficient. On the other hand, if the average particle size is too large, the particles tend to peel off easily, resulting in insufficient suitability for printing tests.

Even in the case of a solution, the fluororesin becomes scattered on the film surface in the form of particles upon drying.

During application, the aqueous fluororesin dispersion contains a surfactant for dispersion (for example, a nonionic surfactant), as well as polyvinyl alcohol and other adhesive polymers, polystyrene, and polyacrylic acid esters to prevent shedding. For example, an emulsion of 5 to 4
00 weight coefficient may be used, and fine powders such as silicon dioxide, aluminum oxide, and titanium oxide fine powders may be added, and antifoaming agents and other additives may be added.

The amount of fluororesin dispersion or solution applied is O, O in terms of solid content.
Although it is often done so that the final coverage is 0.2 to 4 hiro (0,
The coating amount should be determined based on the coverage so that it is 5 to 2%.

If the coverage is less than 0.2%, the desired effect will not be achieved sufficiently, while if it exceeds 4%, the coverage will be excessive and the heat-sealability and glue-sealability will be impaired.

The term "coverage rate" as used herein refers to the area covered by the fluororesin particles when the fluororesin-coated surface is observed with an electron microscope.

The film may be coated on one side or both sides, and may be applied not only to the entire surface but also to a part of the film.

Application can be carried out by any method such as roll coating, brush coating, dipping, curtain flow coating, doctor knife coating, and spraying.

Drying may be performed at room temperature or under heating. A reduced pressure drying method is also appropriately employed.

The coefficient of static friction of the film treated in this way is considerably smaller than that of a typical inorganic powder-sprinkled product.

The coefficient of static friction depends on the type of vinyl alcohol polymer film used, its history (heat treatment, stretching, etc.), the type of fluororesin,
In the case of a dispersion, it varies depending on the particle size, amount of coating, drying speed, etc., but for the purpose of the present invention, the coefficient of static friction is 0.6.
Hereinafter, conditions should be selected so that the value is preferably 0.5 or less.

Next, the method of the present invention will be further explained with reference to Examples.

Hereinafter, "parts" and "many" are expressed on a weight basis unless otherwise specified.

Example 1 100 parts of an aqueous dispersion of polytetrafluoroethylene was placed on one side of a polyvinyl alcohol film having a width of 1300 mm and a thickness of 30 μm (polymerization degree of polyvinyl alcohol: 1700, saponification degree: 99.5 molar ratio), which was produced by a casting method. (concentration 60%, average particle size 0.3μ) Antifoaming agent After diluting a small amount of the mixture with water to adjust the concentration to 0.8%, 22
Using 5 mesh rolls, film speed 55 m
7m17+, coat amount (gross) 9.4 l/h
Roll drying was carried out under the conditions of 1-L and then at a roll surface temperature of 140°C.

The coating amount is 0.015 g/m2 in net.

When this film was observed with an electron microscope, it was found that one to several spherical polytetrafluoroethylene particles were scattered independently (the average number was approximately 7.42 x 101).
1 particle/m'), and the coverage of the film surface by the particles was about 1.7% (area).

The static friction coefficient and various physical properties of the thus obtained film were measured.

The results are shown in Table 1. Control example 1 The raw material film of Example 1 (no coating) Control example 2 An aqueous suspension of colloidal silica (average particle size 15 mμ) at a concentration of 1.6 was applied to the raw material film of Example 1 and dried. A film with a coating amount of 0.03 g/e.

Control Example 3 In Control Example 2, the amount of colloidal silica applied was 0.01.
．． When 5 g/yyf'.

Control example 4 The raw material film of Example 1 was coated with an aqueous dispersion of polystyrene (
The film was coated with a film with a density of 1.6 and an average particle size of 01 μm, and the dry coating amount was o, o3 g/m in net.

The results of the above Control Examples 1 to 4 are also shown in Table 1.

In addition, when experiment 1 was conducted in the same manner as Control Example 2 or 3 except that silicon oxide fine powder with a particle size of 1 μ or more was used instead of colloidal silica, the transparency of the film was impaired, the printing test was poor, and the seal was poor. The results showed that the properties were also slightly inferior to those using colloidal silica.

Examples 2 to 6 The following aqueous dispersion was diluted with water to the film of Example 1 to 0.
A coating with a concentration of 8% was applied and dried.

Example 2 Polytetrafluoroethylene aqueous dispersion 100 parts (concentration 50, average particle size 0.3μ) Polyvinyl alcohol 10 parts (
Polymerization degree 500, saponification degree 99.3 moles) Antifoaming agent
Small amount* Example 3 Polychlorotrifluoroethylene aqueous dispersion (concentration 60%
, average particle size 0.3μ) Example 4 Tetrafluoroethylene-hexafluoropropylene copolymer aqueous dispersion 100 parts (concentration 50%, average particle size 0.4μ) Polyvinyl alcohol 10 parts (polymerization degree 500, saponification degree 99.3 mol φ) Example 5 Polyvinylidene fluoride aqueous dispersion Example 6 Polyvinyl fluoride aqueous dispersion The results are shown in Table 2.

Example 7 A film with a width of 250 mm and a thickness of 4 manufactured by T-die melt extrusion method
An aqueous dispersion of polytetrafluoroethylene ( Concentration 60%, average particle size 0.
3μ) was diluted with water to a concentration of about 1 part, and then applied and dried.

Comparative example 5 Raw material film of Example 7 Comparative example 6 Aqueous suspension of colloidal silica (average particle size 15 mμ) was added to the raw material film of Example 7 at a net weight of 0.03 g/m.
Coated and dried.

Control Example 7 The raw material film of Example 7 was coated with an aqueous polystyrene dispersion (
The film was coated with a film with a concentration of 16% and an average particle size of 0.1μ, and the dry coating amount was approximately o, o3g/= in net.

Example 8 A water diluted solution of a milky white 20% organic solvent solution or dispersion of polytetrafluoroethylene (Neoflon ND-2, manufactured by Daikin Industries, Ltd.) was applied to the raw material film of Example 7, and the dry coating amount was 0 on a net basis. .02** g/m2 film.

Above Examples 7-8, Shown in the table.

The results of Control Examples 5 to 7 are summarized in the third example.
mm, one sheet of α-dodecene-modified trivinyl alcohol film with a thickness of 30μ, copolymerization ratio of α-dodecene of 50 molφ, degree of saponification of vinyl acetate component of 99.5 mol%) was cut into two sheets, front and back, to make a flat film. I got it.

Next, an aqueous dispersion of polychlorotrifluoroethylene (concentration 60, average particle size 0.3μ) diluted with water to a concentration of about 1% was applied to one side of this film, dried, and then applied to the other side. Similar treatment was applied.

Comparative example 8 Raw material film of Example 9 Comparative example 9 Colloidal silica (
An aqueous suspension with an average particle size of 15 mμ) was mixed with a net o, 03
The painted surface was painted and dried for gim.

Control Example 10 An aqueous polystyrene dispersion (concentration 16, average particle size o, iμ) was applied to both sides of the raw material film of Example 9, and the net coating amount per one side was o, o3sym2 after drying.

Example 10 A milky white organic solvent solution or dispersion of polychlorotrifluoroethylene diluted with water was applied to both sides of the raw material film of Example 9, and the dry coating amount per one side was 0.039/m in net. film.

The results of Examples 9 and 10 and Control Examples 8 and 10 are shown in Table 4.

Claims (1)

[Scope of Claims] 1. A surface characterized by applying a fluororesin dispersion or solution to the surface of a vinyl alcohol polymer film and drying the film, so that the coverage of the film surface with the fluororesin is 0.2 to 4φ. A method for producing treated vinyl alcohol polymer films. 2. The method according to claim 1, wherein the dispersion is an aqueous dispersion. 3 The average particle size of the fluororesin in the aqueous dispersion is 0.08 to 0.
．． 8μ. The method according to claim 2. 4 The average particle size of the fluororesin in the aqueous dispersion is 01 to 0.6
The method according to claim 2, wherein μ. 5. The method according to claim 1, wherein the surface-treated film has a static friction coefficient of 0.6 or less. 6. By applying a fluororesin aqueous dispersion having an average particle size of 0.08 to 0.8 μm on the surface of the vinyl alcohol polymer film and drying it, the coverage of the fluororesin particles is increased to 0.2 to 0.2 μm.
4. The method according to claim 1, wherein the coefficient of static friction of the film after being coated with a fluororesin is adjusted to 0.6 or less. 7. Claim 1, wherein the fluororesin is at least one resin selected from the group consisting of polytetrafluoroethylene, polychlorotrifluoroethylene, and tetrafluoroethylene-hexafluoropropylene copolymer.
or the method described in paragraph 6.