JP2744948C - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial applications>   The present invention relates to a polyester film containing a myriad of fine bubbles on its surface and inside.
About film. Specifically, by containing fine closed cells,
The film has a reduced apparent specific gravity, and has whiteness, hiding degree and adhesiveness
The present invention relates to a stretched polyester film having excellent properties. <Problems to be solved by conventional technology and invention>   Conventionally, polyester film has excellent mechanical properties, electrical properties, and chemical resistance
Since it has heat resistance and the like, it is widely used in various industries. Toriwa
The biaxially stretched polyethylene terephthalate film is flatter than other films
It has excellent dimensional stability and is offered to the market at relatively low cost.
It is an indispensable material for information base materials.   For example, one of the products used in offices and conference rooms is an electronic white board.
The important part of the electronic whiteboard, namely the copyboard part, is a white polyester film.
Telephone cards and railway cars
Magnetic cards typified by flashless cards also use the white filter as a base material.
Lum is used, and the excellent characteristics as described above are unfortunately exhibited.   However, although the white film has excellent properties, it increases the degree of concealment.
Various adverse effects are caused by the extremely large amount of white pigments
. That is, the film sometimes contains inorganic particles having a large specific gravity, for example, titanium oxide particles.
Of 10% by weight or more, the apparent specific gravity of the film is 1.7 or more.
Reaches 2.0 or more, which is a unit volume per unit compared to a normal film without the addition of a pigment.
Weight increases by 20 to 50%.   Such an increase in apparent specific gravity is a cause of increasing daily slack due to its own weight.
You. For example, in the case of the above-mentioned electronic white board, if it has been used for a long time,
It has become a very fast process, and has significantly reduced product value.   Also, the inorganic particles in such a white film increase the rigidity of the film itself.
The knife life in film slitting and card cutting
It may cause shortening or cut the hand at the film edge during processing.
There were also problems in productivity, handling workability, and the like.   At the same time, when obtaining a film product of a certain required area,
Of course, the work load also had to be large.   Therefore, the present inventors have tried to reduce the apparent specific gravity in order to solve these problems.
As a result, for example, as proposed in Japanese Patent Application No. 61-313896, a film is formed into a foam structure.
Into a polyester film containing microbubbles.
Has been found to be able to significantly improve the daily slack. The film is finely dispersed
Hidden properties are also provided by the closed cells, which reduces the amount of pigment added.
Coupled with the ability to reduce the film stiffness,
The service life of the knife at the time of construction was greatly extended, and the number of cuts at the film edge was gradually reduced.   However, a polyester foam containing fine bubbles that has achieved such an excellent effect.
But not necessarily sufficient in terms of other film properties
Was. That is, the film has large irregularities on its surface.
The adhesion, which was thought to improve rather than the conventional white film, was unexpectedly
It turned out to be inferior. In addition, the blurring of printed images is also newly pointed out.
It was necessary to improve these problems.   By the way, various surface treatments are usually applied to improve the adhesiveness of the polyester film.
Applying is a well-known fact. For example, flame treatment, solvent treatment, surface coating treatment
Treatment, corona discharge treatment, plasma treatment, ultraviolet treatment, ion putting treatment,
Radiation treatment, sand blast treatment, etc.
Proposals have been made to improve the adhesion.   However, such surface treatments have traditionally been mainly flat, regular polyester fibres.
This was done on the surface of a very rough
There are no examples for ester films.   The reason for this is that a film with a relatively large roughness conventionally has improved adhesion.
Is not necessary. That is, the greater the roughness, the more
The contact area with the adhesive layer increases, and the anchor of the adhesive layer itself that has penetrated deeply into the recesses
-Generally, it is considered that the adhesive strength is improved because the effect is increased.
In fact, the results obtained were almost explained by the concept.   Therefore, as described above, the roughness is extremely large as in the film of the present invention.
In this case, it is clear that this conventional approach to adhesiveness has been overturned.
The conventional surface treatment methods for improving adhesion cannot always be simply applied.
Is shown. Furthermore, internal bubbles are created like the film according to the present invention.
A new method for improving the adhesion of films with special surface shapes
It is not always easy to predict and it is not entirely clear what method is effective
It was no exaggeration to say the current situation.   However, among such various surface treatments, it is effective for the film according to the present invention.
There is plenty of potential to find a way, and it's worth investigating each one.
Was. However, there is a method of impairing the basic characteristics of the film of the present invention having special characteristics.
Needless to say, it cannot be adopted, but a method that can be manufactured easily and at low cost is selected.
Doing so was an important industrial factor. <Means to solve the problem>   In view of such circumstances, the present inventors have investigated the adhesive properties of a polyester film containing fine bubbles.
As a result of diligent investigations for improving the quality, the present inventors have reached the present invention.   That is, the gist of the present invention is that the surface roughness (Ra) is 0.25 μm or more,
At least one axis having a specific gravity of 0.4 to 1.3 and a hiding degree of 0.2 or more
On one or both sides of polyester film containing microbubblesThickness 0.0
1-0.5 μmA film provided with a coating layer, wherein the coating layer in the coating layer
0.1 to 3.0 wt% anionic or nonionic interface with respect to the solid content to be formed
A film characterized by containing an activator.   Hereinafter, the present invention will be described in detail.   The polyester in the present invention includes terephthalic acid, isophthalic acid, naphthalenediene
Aromatic dicarboxylic acids such as carboxylic acids or esters thereof, and ethylene glycol
, Ethylene glycol, 1,4-butanediol, neopentyl glycol, 1
Manufactured by polycondensation with glycol components such as 1,4-cyclohexanedimethanol
Polyester.   These polyesters react directly with the aromatic dicarboxylic acid and the glycol component.
In addition to alkyl esters of aromatic dicarboxylic acids and glycol components
And transesterification, followed by polycondensation or aromatic dicarboxy. It can also be produced by a method such as polycondensation of diglycol ester of acid.
You.   Representative examples of such polyesters include polyethylene terephthalate and polyether.
Tylene-2,6-naphthalate or polybutylene terephthalate, and the like.
It is. This polyester may be a homopolymer or a third component copolymerized.
It may be a polymer. In any case, in the present invention, ethylene terephthalate
Rate units and / or ethylene-2,6-naphthalate units and / or butylene
The terephthalate unit is at least 70 mol%, preferably at least 80 mol%, more preferably
Preferably, a polyester having 90 mol% or more is used.   In the present invention, if the degree of polymerization of the polyester is too low, the mechanical strength is low.
The intrinsic viscosity of the polyester is 0.4 or more, preferably 0.5 to 1.
2, more preferably 0.55 to 0.85.   Now, when making a normal polyester film into a film,
Is the surface of the film, so as not to impair the slipperiness between the film and metal rolls.
Uses polyester containing moderately fine inert particles as a roughness-imparting agent
However, the polyester used in the present invention preferably does not contain such inert fine particles.
New This is because of the control of whiteness and hiding degree of the film obtained by the inert fine particles.
This is because it may interfere with your business. However, the characteristics of the film
As long as there is no hindrance to the properties, even if a polyester containing such inert fine particles is used,
There is nothing wrong.   In the present invention, a film is produced using the polyester described above.
However, the film is a film having a structure having fine closed cells on its surface and inside.
The apparent specific gravity of the film needs to be 0.4 or more and 1.3 or less.
It is preferably 0.6 or more and 1.3 or less, more preferably 0.8 or more and 1.3 or less.
is there. That is, if the apparent specific gravity exceeds 1.3, the daily weight of the film due to its own weight will increase.
No longer has any effect on sagging, whereas below 0.4 the mechanical strength of the film
Is not preferable because of lack.   The hiding degree of the film of the present invention is required to be 0.2 or more, preferably
Is 0.3 or more. When the hiding degree is less than 0.2, the presence of the
Not only does the diameter of the bubbles become larger and the mechanical strength decreases, but also for white films
When used, it is not preferable because a large amount of pigment must be added.   It is also necessary that the film of the present invention is stretched in at least one direction.
The stretching ratio is 4 times or more, preferably 9 times or more in area ratio.
Is preferred. That is, the unstretched polyester film is filled as is well known.
This is because of poor mechanical strength.   The film of the present invention needs to have the above-mentioned properties,
Unless the structure is contained and does not impair such properties and requirements, its manufacturing method
The law is not particularly limited. That is, a structure containing such fine bubbles is manufactured.
For example, Japanese Patent Application Laid-Open No. 50-38765 and Japanese Patent Publication No.
For adding a gas or a vaporizable substance as described in No. 56, etc.
Method; described in JP-A-52-43871 and JP-B-58-50625.
A method of adding a substance that generates gas by utilizing chemical decomposition as described above;
Alternatively, it is described in JP-A-51-34963 and JP-B-52-27666.
Add a substance that is soluble in the solvent as described, and after molding, impregnate the liquid and extract.
And any other method may be used. However, these manufacturing methods
Is a method that can be easily adopted because it involves special molding equipment and complicated manufacturing processes.
Is not always hard to say.   Therefore, as a method for obtaining the polyester film containing fine bubbles of the present invention, for example,
For example, Japanese Patent Application No. 61-313896 proposed by the present inventors (Japanese Patent Application Laid-Open No. 63-16 / 1988). No. 8441) is preferably employed.   That is, a specific polypropylene is blended with polyester and extruded into a sheet.
Then, the sheet is stretched at least uniaxially to form a film.
For more information, polyester has a melt flow index (hereinafter abbreviated as MFI).
) A crystalline polypropylene homopolymer of 0.2 to 120 is blended in an amount of 3 to 20 wt%.
Melt extruding into a substantially amorphous sheet, which is then at least
Can be formed into a film by stretching in an uniaxial direction at an area magnification of 4 times or more.
Polyester film containing numerous closed cells on the surface and inside
How to   By adopting such a method, the apparent specific gravity of the film of the present invention is 0.4 to 1.3, and
The degree of concealment is 0.2 or more, the surface roughness (Ra) is 0.25 μm or more,
It is possible to easily obtain a film stretched at least in a uniaxial direction. Only
Also without the modification of the conventional film forming equipment
Manufacturing cost, the benefits of adding manufacturing costs are extremely large
.   This method will be described in more detail. Crystalline poly compounded in such a method
The propylene homopolymer is at least 95 mol% or more, preferably 98 mol%.
% Or more is a polymer having a prolene unit. That is, the polypropylene used
When ren is amorphous, it bleeds out on the surface of amorphous sheet
However, it is not preferable because it contaminates the surface of the cooling drum, the stretching roll and the like. Also take
For example, if ethylene units are copolymerized in polypropylene by 10 mol% or more,
It is not preferable because fine bubbles cannot be sufficiently contained in the inside of the stretched film.   The M.P. F. I. Is 0.2 to 120, preferably 0.5 to
50 is preferred. That is, M. F. I. Is less than 0.2, the generated bubbles
It becomes extremely large and breaks frequently during stretching. F. I. Exceeds 120
Any loss such as clip detachment during stretching in the tenter
This is not preferred.   The blending amount of the polypropylene is preferably 3 to 20% by weight. That is, the composition
When the amount is less than 3 wt%, the amount of fine bubbles generated is small, and the apparent specific gravity of the film is reduced.
It is difficult to achieve 1.3 or less, while if it exceeds 20 wt%, breakage occurs during stretching.
Not preferred.   On the other hand, in such a method, it is necessary to further stretch at least uniaxially.
Case. This is not just for the purpose of providing sufficient mechanical strength as described above.
Instead, simply blending polyester and polypropylene makes fine closed cells
Cannot be provided, and this is achieved only when the stretching step is used in combination.   Such a stretching method itself does not require any special operation, and is a normal polyester film.
Is carried out under the same conditions as in the production of Ie polyester and polypropylene
Using the extruder at 250-300 ° C
And cooled to about 70 ° C. or less to form a substantially amorphous sheet. Then
The sheet is stretched in the longitudinal and / or transverse directions at an area magnification of 4 times or more, preferably 9 times or more.
The heat treatment is further performed at 120 to 250 ° C. to obtain an apparent specific gravity of 0.1 according to the present invention.
It is possible to easily produce a film having a hiding power of 0.2 or more that is 4 or more and 1.3 or less.
it can.   Thus, the film of the present invention was produced as a white film having high hiding power.
However, as long as the basic characteristics are not impaired, various additives are blended according to various uses.
There is nothing wrong with it. Such additives include, for example, antioxidants, ultraviolet absorbers.
Collecting agents, lubricants, antistatic agents, dyes, pigments, optical brighteners, matting agents, surfactants, etc.
And an appropriate amount can be added as required by an appropriate method.   For the film thus obtained, in the present invention to improve the adhesive force,
It is necessary to provide a coating layer on one side or both sides.   Among the many surface treatment methods mentioned above, for example, the flame treatment method
Is not preferable because the reproducibility of the adhesive strength is poor. Solvent treatment also reduces mechanical strength
And the solvent penetrates into the air bubbles in the film, making it difficult to remove them.
Therefore, it is not preferable.   On the other hand, the corona treatment method and the plasma treatment method are effective for improving the adhesion.
However, since the adhesive force decreases with time, the adhesiveness after secondary processing is reduced.
Unevenness is not preferred. In addition, the sandblasting method changes the shape of the film surface.
And the film appearance unique to the present invention is hindered.   Therefore, among these many surface treatment methods, the surface coating treatment, that is, the present invention
The most preferable method is to provide a coating layer.
We will take measures to improve the adhesiveness according to the application without impairing the unique texture of Lum.
This is a particularly excellent method because it is easy.   The compound constituting the coating layer of the microbubble-containing polyester film of the present invention has a high content.
It may be a molecular compound or a low molecular compound.
Has a surface layer that does not affect the external appearance and surface roughness of the
If so, a coating material can be selected according to various uses.   For example, thermoplastic resin, crosslinkable resin, or lubricant or antistatic agent
Can be used as needed. Also form a coating layer
Coating agent may be an organic solvent-soluble compound or an aqueous dispersible compound.
I don't know.   More specifically, thermoplastic polyesters soluble in organic solvents; sulfonates, etc.
Water-dispersible thermoplastic polyester containing alkyd polyester; organic
Solvent-soluble or water-dispersible polyurethane resin; polyisocyanate compound;
End-blocked polyurethane resin; vinyl chloride-vinyl acetate, vinylidene chloride
Soluble in organic solvents such as styrene, styrene, vinyl acetate, and acrylic
Is a water-dispersible vinyl resin; epoxy resin; silicone resin; urea resin;
Min-based resins and the like, but in the present invention are particularly limited to these
is not.   That is, the use of the film of the present invention is not specified,
Therefore, the composition of the coating layer is particularly limited because the adhesive properties are different from each other.
It is not of a definable nature. For example, it seems that many proposals have been made
In order to improve adhesion to the magnetic layer using a urethane binder,
A urethane resin-based coating layer exhibits a particularly favorable effect, and is suitable for cellophane ink.
For example, a vinyl resin coating layer is preferable.   However, these findings are for normal flat polyester films.
Extremely rough surface containing bubbles on its surface and inside, like the film of the present invention
There is no example for a large film, and it is not always easy to guess
Was. Furthermore, polyolefin was blended with polyester as the film of the present invention.
When using a composition, it is sufficient that polyolefin is also present on the film surface.
To select a coating agent for a film whose existence is unknown.
Is extremely difficult and must be changed as appropriate for each application.   In the coating layer of the present invention, dyes, pigments, lubricants, antioxidants,
Various additives such as absorbents, antistatic agents, inorganic fine particles, and surfactants are mixed in appropriate amounts
No problem. In particular, the surfactant is mixed with the polyester film layer
It is preferably used in the present invention because it improves wettability between coating layers and improves adhesion.
Can be. That is, when various coating layers were formed in the present invention,
Because of the large number of large protrusions on the surface of the
A surfactant is positively incorporated into the coating agent since the sticking phenomenon easily occurs.   Such a surfactant has a property of being easily collected at an interface between two substances, and the two substances It significantly alters the properties of the interface between them, and in the present invention, the pore containing fine bubbles is used in the present invention.
A compound that has the effect of improving the wettability between the ester film surface and the coating agent
is there. In the present invention, an anionic or nonionic surfactant is used.   As anionic surfactants, for example, higher fatty acid alcohols commonly known as soap
Potassium metal salts; sulfuric acid such as higher alcohol sulfate alkali metal salts and sulfated oils
Acid ester salts; sulfonic acids such as alkali metal salts of alkyl benzene sulfonic acids
Salts; phosphate esters such as higher alcohol ethylene oxide-added metal phosphate salts
And the like.   Examples of nonionic surfactants include, for example, nonylphenylethylene oxide
Polymoles such as nmol adducts and lauryl alcohol ethylene glycol nmol adducts
Alkylene glycol type; lauric acid monoglyceride and pentaerythritol
Multivalent alcohols such as monopalmitate or sorbitan stearic acid triester
Calls and the like.   Other polyalkylenes such as organopolysiloxane and polydimethylsiloxane
Examples include silicon-based surfactants represented by oxide adducts, and anions,
Fluorinated surfactants combined with nonionic surfactants are also included.   The amount of the surfactant added is preferably 0.001 to 1 with respect to the coating solution for the coating agent.
vol%, more preferably 0.01 to 0.5 vol%. Also the coating layer
It is necessary to add 0.1 to 3% by weight based on the solid matter to be formed.   In the present invention, the method for forming the coating layer is not particularly limited, and the coating layer has already been formed.
It may be applied to the filmed material, or it may be applied in the film manufacturing process.
You may.   For example, when providing a coating layer on a biaxially stretched microbubble-containing polyester film,
The coating agent is applied to the film uniaxially stretched in the longitudinal direction, and the coating agent is dried or undried.
The method in which the film is stretched in the horizontal direction and heat-treated immediately is the same as film formation, coating and drying.
This is particularly advantageous because it can be carried out at a certain point and has a great advantage in view of the manufacturing cost.
Adopted.   Coating method is known reverse coater, gravure coater, kiss coater, etc.
Roll coaters and bar coaters can be preferably used, but are not particularly limited to these.
It is not something to be done.   The thickness of the coating layer is unique to the microbubble-containing polyester film used as the substrate of the present invention.
Is in the range of 0.01 to 0.5 [mu] m so as not to impair the surface appearance.   It is necessary that the coating layer is formed on one side or both sides,
When forming a layer, the coating agent may be the same or different.
It can be appropriately selected according to the needs of various uses. <Example>   Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to the gist thereof.
However, the present invention is not limited to the following embodiments. Method of measuring various characteristic values in the present invention
The method was performed by the following method. (1) Apparent specific gravity   Cut out a 10cm x 10cm square from any part of the film,
After measuring the average thickness of any 9 points with a heater to determine the volume, the cut-out film
Weigh 1cm^ThreeThe weight per unit was taken as the apparent specific gravity. The number of measurements is 5
Of the sample, and the average value was used as the measured value. (2) Concealment degree   Using a Macbeth densitometer TD-904, measure the transmitted light density under the G filter.
The degree of concealment was determined. The larger this value is, the higher the hiding power is. Measurement is for 3 points
No average value was taken as the measured value. (3) Surface roughness Ra (μm)   JIS B-06 using SE-3F type surface roughness meter manufactured by Kosaka Laboratory Co., Ltd.
It measured according to the method of 01-1976. As detailed conditions, stylus diameter 2μm, stylus
The pressure was 30 mg, the cutoff was 0.8 mm, and the measurement length was 2.5 mm.
The average value of 10 points excluding the maximum and minimum values was taken as the measured value. (4) Evaluation of ink adhesion   A predetermined ink is applied to the film surface with a # 8 bar coater so that
After drying at 0 ° C. for 2 minutes, an ink print layer was formed. The sample was heated at 23 ° C and 50% R
After leaving it for 24 hours at H, a Nichiban adhesive tape is stuck on the surface of the ink print layer,
A so-called cellophane tape peeling test was conducted in which the adhesive tape was instantly peeled off from one end.
. At that time, the adhesive strength between the ink print layer and the film was visually determined by the following five ranks.
Was. 5 points; no ink print layer peeled off from film 4 points; A very small part of the ink print layer peels off from the film 3 points; Part of the ink print layer peels off from the film 2 points; Most of the ink print layer peeled off from the film, leaving only a part 1 point: The ink print layer is completely peeled off from the film and does not remain at all (5) Evaluation of applicability   After forming the coating layer on the film surface, observe the coating layer surface and check for uneven coating and coating
The state of the ケ was visually judged in each of the following three ranks. (Uneven coating) ；: Uniformly applied, showing the same gloss as the base surface △: Gloss slightly different from the base surface ×: Mura-like gloss clearly different from the base surface (Applying drop) ；: Uniformly applied, no repelling marks found △: Some repelling marks are observed when applying ×; many repelling marks are observed when applying (6) Melt flow index F. I. (G / 10min)   It measured according to the method of JISK-6758-1981. The lower this value, the
Indicates high melt viscosity. Comparative Example 1   Average particle size 0.3μ on polyethylene terephthalate chip with intrinsic viscosity 0.652
m titanium oxide pigment in polyethylene terephthalate in a twin-screw extruder with vent
The raw material which blended and blended 25wt% master batch chips kneaded with 40wt%
Melted at 290 ° C with an extruder and extruded into a sheet on a 40 ° C cooling drum, about 1m
An amorphous sheet having a thickness of m was obtained. Then, the sheet is tripled in the vertical direction and 3.3 in the horizontal direction.
Stretched twice and heat-treated at 240 ° C for 5 seconds to finally give a film thickness of 100 µm, apparent
A biaxially stretched film having a specific gravity of 1.45, a degree of concealment of 0.69, and Ra of 0.05 (μm) was prepared.
Obtained.   Such a film is usually called a white film, and although it has a hiding power,
The specific gravity was large and the film was extremely flat.   The ink adhesion of this film was 5 points with the polyester ink,
3 points for ink, 1 point for UV screen ink, and 1 point for UV offset ink.
Was. Comparative Example 2   Instead of the titanium oxide pigment masterbatch chip used in Comparative Example 1, M.P. F
. I. 5 (g / 10 min) crystalline polypropylene homopolymer chips
The same procedure as in Comparative Example 1 was carried out except that the compound was blended in an amount of 100% by weight.
A film was obtained. The apparent specific gravity of the obtained film was 1.0, the degree of concealment was 0.61,
Ra is 0.5 (μm), the specific gravity is extremely reduced as compared with Comparative Example 1, and the roughness is
of It was a white film with a large unique texture.   The ink adhesion of this film was 2 points with polyester ink,
1 point for ink, UV screen and UV offset ink
The adhesive strength was inferior to that of the ordinary white film shown in Example 1. Comparative Example 3   Instead of the polypropylene used in Comparative Example 2, M.P. F. I. 10 (g / 10m
5% by weight of polypropylene homopolymer chip and fluorescent whitening agent
3% by weight of polyethylene phthalate chips made into a master batch of 1% by weight
A biaxially stretched film having a thickness of 100 μm was finally obtained in the same manner as in Comparative Example 2 except that
Was.   The apparent specific gravity of the obtained film was 1.2, the degree of concealment was 0.46, and the Ra was 0.27.
(Μm), which was a white film having a reduced specific gravity as compared with Comparative Example 1.   The ink adhesion of this film was 3 points with the polyester ink,
2 points for ink and 1 point for UV screen ink and UV offset ink.
The adhesive strength was inferior to Comparative Example 1. Example 1   Using the same raw material as in Comparative Example 2, melted at 290 ° C in an extruder, cooled at 40 ° C
The sheet was extruded into a sheet to obtain an amorphous sheet having a thickness of about 650 μm. Then the sheet
After stretching uniaxially three times in the machine direction, water-dispersible polyester resin (Te
Phthalic acid / isophthalic acid / isophthalic acid sodium sulfonate / ethylene glycol
/ Diethylene glycol / triethylene glycol based condensation polymer) 20wt
%, Water-dispersible polyester polyurethane resin (terephthalic acid / isophthalic acid / di
Methylpropionic acid / ethylene glycol / diethylene glycol / isophorone
79.5% by weight of diisocyanate polymer and anionic surfactant (dode
An aqueous dispersion containing 0.5 wt% of sodium benzene sulfonate) was applied and
After stretching 3.3 times in the transverse direction, heat treatment was performed at 240 ° C. for 5 seconds.
A 100 μm thick biaxially stretched film having a cloth layer thickness of 0.1 μm was obtained.   The apparent specific gravity of the obtained film is 1.0, the degree of concealment is 0.61, and a coating layer is provided.
The Ra of the contacted surface is 0.5 (μm), showing exactly the same characteristics as Comparative Example 2, and the surface texture is also
The white film was almost unchanged from Comparative Example 2.   The ink adhesion of this film was 5 points with the polyester ink,
5 points for ink, 4 points for UV screen ink and 5 points for UV offset ink.
A remarkable improvement over Comparative Example 2 was observed. Also shows better adhesion than Comparative Example 1.
did.   On the other hand, when the coating layer was observed, the coating unevenness was ranked ○, and the coating ケ
And the applicability of the coating agent was extremely good. Example 2   The surfactant in the aqueous dispersion used for forming the coating layer in Example 1 was replaced with a nonionic surfactant.
To 1 wt% of a surfactant (lauryl alcohol ethylene glycol nmol adduct)
Except that an aqueous dispersion containing 79% by weight of a polyester polyurethane resin is used.
As in Example 1, a 100 μm-thick biaxial finally having a coating layer of 0.1 μm
A stretched film was obtained.   The apparent specific gravity of the obtained film was 1.0, the degree of concealment was 0.61, and Ra was 0.51.
(Μm), showing the same film properties as Comparative Example 2, and almost the same surface texture.
This was a white film.   The ink adhesiveness of such a film is a polyester ink and a cellocolor ink.
5 points for UV screen ink and 4 points for UV offset ink
As in the case of No. 1, an improvement in the adhesive strength was observed.   In addition, coating unevenness of the coating layer is rank 、, coating non-appearance is rank △, and coating property is good. Was something. Comparative Example 4   The surfactant in the aqueous dispersion used for forming the coating layer of Example 1 was not blended, and
Except that the stell polyurethane resin was changed to 80 wt%,
Finally, a 100 μm thick film having a coating layer thickness of 0.2 μm was obtained.   The apparent specific gravity of the obtained film was 1.0, the degree of concealment was 0.61, and Ra was 0.52.
(Μm) and almost the same film characteristics and table as Comparative Example 2 in which no coating layer is formed.
Surface texture was shown.   The ink adhesion of such a film depends on the ink for polyester and the cello color ink.
5 points, UV screen ink and UV offset ink 4 points, good
Showed excellent adhesion.   On the other hand, the coating unevenness of the coating layer was rank △, and the coating loss was rank x, which was a practical problem.
Although there was no level, the coatability was somewhat poor.   The results of the film characteristics of Comparative Examples 1 to 4 and Examples 1 and 2 described above are summarized and summarized.
1 is shown. * 1 PES: Water-dispersible polyester resin (terephthalic acid / isophthalic acid / a
Sodium phthalate sulfonate / ethylene glycol / diethylene glycol /
Polyethylene glycol-based condensation polymer) * 2 PU: Water-dispersible polyester polyurethane resin (terephthalic acid / isophthalic acid)
Talic acid / dimethyl propionic acid / ethylene glycol / diethylene glycol /
Isophorone diisocyanate polymer) * 3 Anionic: Anionic surfactant (sodium dodecylbenzenesulfonate)
Da) * 4 Nonionic surfactant: Nonionic surfactant (lauryl alcohol ethylene glycol
Coal nmol adduct) <Effect of the Invention>   As described in detail above, the fine-bubble-containing polyester film of the present invention is coated on the surface thereof.
The film on which the fabric layer has been formed is exposed to the surface of the substrate, that is, the air contained on the surface and inside.
Adhesion can be improved with little loss of the unique texture created by the foam, and printability
Became better.   In other words, conventional surface treatment methods are effective for certain printing inks.
Even if it has no effect on other inks, or the adhesive strength decreases with the passage of time,
In many cases, such as reducing the whiteness of the film,
A major feature of the film of the invention is that it can provide effective adhesiveness according to various uses.
It is.   In other words, the coating layer is optimal for various uses and also provides a strong adhesive force.
The ability to make a suitable choice and easily make the change is a matter
The use of the foam-containing polyester film can be expanded, and its merits are extremely large.

Claims (1)

(1) The surface roughness (Ra) is 0.25 μm or more, and the apparent specific gravity is 0.4 to 1.3.
A film provided with a coating layer having a thickness of 0.01 to 0.5 μm on one or both sides of a microbubble-containing polyester film stretched at least uniaxially and having a hiding degree of 0.2 or more, A film characterized in that the coating layer contains an anionic or nonionic surfactant in an amount of 0.1 to 3.0 wt% with respect to a solid content forming the coating layer.