JPS62173252A - High-transparent easily adhesive film and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a highly transparent and easily adhesive film and a method for producing the same, and more specifically to highly processed products such as membranes, graph inks, substrates for optoelectronic products, etc. The present invention relates to a polyester film having high transparency and easy adhesion that is useful as a polyester film, and a method for producing the same.

<Prior Art> It is known to melt-extrude thermoplastic polyesters, such as polyethylene terephthalate or its copolymers, polyethylene naphthalate or its copolymers, or blends of these with small proportions of other resins, to form films. be.

It is also known that the resulting biaxially stretched and heat-set polyester film has better heat resistance, gas barrier properties, electrical properties, and chemical resistance than films made of other resins. However, since its surface is highly crystal oriented, it has high cohesion on one surface and has poor receptivity to paints, adhesives, inks, and the like.

Therefore, when a synthetic resin layer is provided on the surface of such a polyester film, the surface of the film is activated by subjecting it to corona discharge treatment, ultraviolet irradiation treatment, plasma treatment, or flame treatment in order to strengthen the adhesion between the two. Additionally, a method of coating with a synthetic resin coating has been applied. However, although these methods of activating the film surface can be expected to improve adhesion to the coating layer by increasing the secondary bonding force due to wetting, the activity decreases over time. Therefore, these means of activating the film surface are not necessarily satisfactory.

As another method for increasing the receptivity of the polyester film surface, etching methods have been proposed in which the surface is swollen or partially dissolved with various agents. This protects the film surface from acids and alkalis.

The surface of the film is etched by contacting with an aqueous amine solution, trifluoroacetic acid, or phenols, etc., to decompose the crystal orientation near the surface, ease dissolution, etc., and at the same time reduce cohesion and improve adhesion to the binder resin. The effect is most reliable, and the adhesion between the film and the layer provided thereon, such as a synthetic resin coating layer, becomes strong. However, some of the chemicals used in this method are harmful and can be dangerous to handle, and volatilized substances from the chemicals are released into the atmosphere, so thorough precautions must be taken to avoid contaminating the working environment. There are various disadvantages in practical terms, such as the need for

As a method similar to this method, one layer of primer (undercoat layer) is provided on the surface of the film in advance, a thin surface layer that is different from the base film is formed, and then a desired layer, such as a synthetic resin layer, is coated. When forming the undercoat layer, the coating process is usually carried out in a process different from the polyester film forming process.However, highly processed products such as membranes.

In applications where precise and delicate quality must be maintained, such as graphics and optoelectronics,
Even if five easily adhesive surfaces are formed, if the resulting film has surface defects due to dust, it cannot be used as a base film for these purposes, but this defect is likely to occur in this separate process. Therefore, it is desirable to perform the undercoating process in an atmosphere as free from dust as possible. There is a polyester film forming process that satisfies these conditions, and by performing an undercoating process in this process, it will be possible to obtain a product that can be fully used for the above-mentioned advanced film processing products.

On the other hand, in the prior art, the method of modifying the surface of a polyester film to an easily adhesive surface by treating the surface with a primer is often achieved by applying a composition dissolved in an organic solvent to the surface of the film. It's here. If such a method is carried out during film production, the fugitive organic solvent may contaminate the surrounding environment, cause unfavorable safety and hygiene conditions, and have a negative impact on the film forming process, so the use of organic solvents should be kept to a minimum. It should be stopped. Therefore, when performing in-line subbing treatment in the film forming process, it is preferable to use a composition using water as a solvent from the viewpoints of process, economy, and safety. Therefore, many primer compositions using water as a solvent have been proposed, and in particular, Boliure! Many proposals have been made for aqueous solutions or dispersions of polyesters and polyesters. However, these primer compositions focus on imparting easy adhesion and do not consider imparting slipperiness, so for example, when the composition is applied to a transparent flat polyester film, the resulting coated product may cause adhesive blocking. , there was a strong tendency for the coefficient of friction to increase, making handling difficult. On the other hand, improving the slipperiness of the film,
One method for improving handling properties is to add a granular lubricant to BolJ ester to form a film, but in this case, the lubricant reduces the transparency of the film, especially in the case of thick films of 25 μm or more, the light transmittance decreases. was large, and its uses were limited. This reduction in light transmission cannot be improved by the above primer composition.

As mentioned above, until now, it has been difficult to provide a single layer of primer on a highly transparent and flat film to provide a film with both easy adhesion and slipperiness, thereby providing a film with good no-undling properties.

<Object of the invention> The object of the present invention is to apply various coatings applied to polyester films, such as cellophane ink, UV ink, offset ink, gravure ink, diazo paint, hard coat agent, matte paint, gelatin composition, etc. It is an object of the present invention to provide a highly transparent polyester film provided with a single layer of primer that has excellent adhesion to. Another object of the present invention is to provide a preferred method for producing such a highly transparent and easily adhesive polyester film.

<Configuration of the Invention> According to the present invention, an aqueous polyurethane is coated with two or more epoxy groups on at least one side of a polyester film having a center line average roughness (Ra) of 0.02 μm or less. The light transmittance (550 nm) is 80%.
An aqueous primer coating solution containing polyurethane and an epoxy compound having two or more epoxy groups is applied to at least one side of the above highly transparent and easily adhesive film and the polyester film before crystal orientation is completed, and then dried and stretched. , by a method for producing a highly transparent and easily adhesive film, which is characterized by heat treatment to complete crystal orientation, center line average roughness (Ra) of 0.02 μm or less, and light transmittance (550 nm) of 80% or more. achieved.

In the present invention, polyester is a linear saturated polyester synthesized from an aromatic dibasic acid or its ester-forming derivative and a diol or its ester-forming derivative. Specific examples of such polyesters include polyethylene terephthalate, polyethylene isophthalate fuvobutylene terephthalate, and poly(1,4-cyclohexylene dimethylene terephthalate).

Examples include polyethylene-2,6-naphthalene dicarboxylate, and also include copolymers thereof or blends of these with small proportions of other resins.

The polyester film of the present invention is obtained by melt-extruding such a linear saturated polyester resin, forming it into a film by a conventional method, and subjecting it to orientation crystallization and heat treatment crystallization. This polyester film is crystal oriented to such an extent that the heat of crystal fusion measured by a scanning calorimeter in a nitrogen stream [at a heating rate of 10° C./min] usually exhibits a value of 4 ad, /, 51 or more. is preferred.

In the present invention, the surface roughness of the polyester film is specified by the center line average roughness Ra, and Ra is 0.02.
It is less than μm, preferably 0.015 μm. Further, the film has a transmittance of 80 cm or more for light having a wavelength of 550 nm. Such a transparent flat film can be obtained by adding no fine particles to the polyester or by adding a small amount of particles having a small size. Moreover, it is preferable that the polyester film has a thickness of 25 to 300 μm.

In the present invention, a polyester film before completion of crystal orientation at °C refers to an unstretched film obtained by thermally melting the polymer and forming it into a film as it is; an unstretched film oriented in either the vertical direction or the horizontal direction. A uniaxially stretched film that has been further stretched and oriented at a low magnification in both the vertical and horizontal directions (a biaxially stretched film before being finally re-stretched in the vertical or horizontal direction to complete oriented crystallization) ) etc.

The aqueous primer coating liquid used in the present invention contains an aqueous polyurethane and an epoxy compound having two or more epoxy groups.

This water-based polyurethane has an increased affinity for water, for example, by a carboxylic acid group, a sulfonic acid group, or a sulfuric acid half-ester base, and such water affinity-imparting groups are usually introduced during or after the synthesis of the polyurethane. For example, the introduction of carboxylic acid groups during polyurethane synthesis
Either a carboxylic acid group-containing polyhydroxy compound is used as one of the raw material polyhydroxy compounds, or a hydroxyl group-containing carboxylic acid or an amine 7 group-containing carboxylic acid is reacted with the incyanate group of polyurethane having unreacted incyanate groups, and then the reaction is performed. This can be carried out by adding the product to an aqueous alkaline solution under high speed stirring and neutralizing it.

In addition, the introduction of a sulfonic acid group or a sulfuric acid half-ester group is usually carried out by forming a prepolymer from a polyhydroxy compound, a polyincyanate, and a chain lengthening agent, and then adding a sulfonic acid group and a 7-mino group or a hydroxyl group that can react with the terminal incyanate group to the prepolymer. This can be carried out by adding and reacting a compound having an acid base or a sulfuric acid half ester base in its molecule to finally obtain an aqueous polyurethane having a sulfonic acid group or a sulfuric acid half ester base in its molecule. In this case, it is preferable to carry out the formation reaction in an organic solvent, then add water and then remove the solvent. Another method is to synthesize a polyurethane having a sulfonic acid group using a compound having a sulfonic acid group as one of the raw materials, and then neutralize the polyurethane by adding it to an alkaline aqueous solution under high-speed stirring. Method: A sulfonic acid alkali salt (e.g. -So
, Na, etc.). As the alkaline aqueous solution, it is preferable to use an aqueous solution of sodium hydroxide, potassium hydroxide, ammonia, furkylamine, etc., but the alkali does not remain in the coating film (undercoat film) (ammonia evaporates under drying conditions). Amines are particularly preferred.The amount of bases such as carboxylic acid groups, sulfonic acid groups, sulfuric acid half ester bases, etc. is preferably 5 to 15% by weight.

If the proportion of the base is too small, the water affinity of the polyurethane will be insufficient, making it difficult to prepare a coating solution, and if it is too large, the inherent properties of the polyurethane will be impaired, which is not preferable. Such a water-based polyurethane can be prepared by using a dispersant if desired.
It forms a stable aqueous dispersion or an aqueous solution.

Examples of polyhydroxy compounds used in the synthesis of polyurethane include polyethylene glyfur, polypropylene glycol, polyethylene propylene glycol, polytetramethylene glycol, hexamethylene glycol, tetramethylene glycol, 1,5-bentanediol.

Diethylene glyfur, triethylene glyfur, polycaprolactone, polyhexamethylene adipate, polyhexamethylene sebacate.

Polytetramethylene adipate, polytetramethylene sebacate, trimethylol propane, trimethylol button, pesotaerythritol.

Glycerin and the like can be mentioned. Examples of the polyisocyanate compound include hexamethylene diisocyanate, diphenylmethane diisocyanate, tolylene diisocyanate, inhopane diisocyanate, and an adduct of tolylene diisocyanate and trimethylolethane.

Examples include adducts of hexamethylene diinocyanate and trimethylolethane.

Examples of carboxylic acid-containing polyols include dimethylolpropionic acid and dimethylolbutyric acid.

Examples include dimethylolvaleric acid and trimellitic acid bis(ethyleneglyfur) ester. As a carboxylic acid containing a 7-mino group.

For example, β-aminobutyric acid, p-pionic acid, γ-7minobutyric acid, p-
Examples include 7s benzoic acid. Examples of hydroxyl group-containing carboxylic acids include 3-hydroxypropionic acid, r-hydroxybutyric acid, P-(2-hydroxyethyl)
benzoic acid.

Examples include malic acid. Examples of compounds having an amino group or a hydroxyl group and a sulfonic group include aminemethanesulfonic acid, 2-aminoethanesulfonic acid, and 2-aminoethanesulfonic acid.
Examples thereof include 7/-5-methylbenzene-2-sulfonic acid, sodium β-hydroxyethanesulfonate, aliphatic di-primary amine compound pudipan sultone, butane sultone addition products, and preferably aliphatic di-primary amine compounds. Examples include propane sultone adducts of grade amine compounds. Furthermore, examples of compounds containing an amino group or a hydroxyl group and a sulfuric acid half-ester group include aminoethanol sulfate, diamine diamine ethanol sulfate, aminobutanol sulfate, hydroxyethanol sulfate, γ-hydroxypusibanol sulfate, α-hydroxybutanol sulfate. etc. can be mentioned.

Polyurethane can be synthesized using these compounds by conventionally well-known methods.

Examples of epoxy compounds having two or more epoxy groups that crosslink with aqueous polyurethane include 1, where e=1 to 13 CH, -OH C-CHx C-CHt 0-CHt-C-CH.

1 0'-O''Q'C
H.

Preferred examples include aliphatic epoxy compounds such as.

The aqueous primer coating liquid used in the present invention may be an aqueous solution or an aqueous dispersion (but is not limited to the percentage).The ratio of the aqueous polyurethane to the epoxy compound is 100 parts by weight of the former to 1 to 40 parts by weight, further 2
It is preferable that it is 30 parts by weight. If the proportion of the epoxy compound is too high, the adhesion properties will be lowered, and if it is too low, the solvent resistance will be lowered, making it difficult to obtain a good coated surface when the coating is applied, which is the object of the present invention, which is not preferable. The crosslinking reaction between water-based polyurethane and epoxy compounds proceeds even at low temperatures. Therefore, 1. the primer composition of the present invention has the advantage that even if the heating conditions such as drying of the wrapping solution are insufficient, the crosslinking density increases over time, and a primer with constant solvent resistance can always be obtained. ing.

The aqueous ply 7-coating solution is prepared by dissolving or dispersing the above two components in an aqueous medium, and is used by adding a required amount of surfactant such as anionic surfactant or nonionic fine surfactant. be able to. Such a surfactant is preferably one that can lower the surface tension of the aqueous coating solution to 40 dyne/F or less and promotes wetting to the polyester film, such as polyoxyethylene alkylphenyl ether, polyoxyethylene fatty acid ester, and nrubitan. Fatty acid ester, glycerin fatty acid ester, fatty acid metal soap, alkyl sulfate, alkyl sulfonate,
Examples include furkylsulfosuccinate, quaternary ammonium chloride, and alkylamine hydrochloride. Furthermore, antistatic agents and ultraviolet absorbers, for example, may be added to the extent that the effects of the present invention are not lost.

Pigments, organic fillers, inorganic fillers, lubricants.

Other additives such as anti-bootking agents can be mixed.

The aqueous primer coating solution may be applied to the polyester film in a normal coating process, that is, in a process of coating the biaxially stretched and heat-set polyester film separately from the film manufacturing process. However, in this process,
Coating in a clean atmosphere is desirable for highly processed products as it easily traps dust and other substances.

From this point of view, coating during the polyester film manufacturing process is preferable. In particular, it is preferable to apply an aqueous primer coating liquid to one or both sides of the polyester film before the crystal orientation is completed during this step. In this case, the solid content concentration of the aqueous primer coating liquid is usually 30% by weight or less, more preferably 10% by weight or less. The amount of coating is 0.5 to 20 g per 1 d of running film, and &'! l~
log is preferred.

Any known coating method can be used as the coating method.

For example, roll coating method, gravure coating method, -luplash method, spray coating.

It is preferable to apply the air knife foot method, the impregnation method, the curtain foot method, etc. alone or in combination.

The polyester film coated with the aqueous coating solution is dried and subjected to processes such as stretching and heat setting. For example, a longitudinally stretched polyester film coated with an aqueous primer coating solution is guided into a stenter, where it is laterally stretched and heat-set.

During this time, the coating solution dries and further undergoes a crosslinking reaction, forming a continuous film on the film. Heat for the crosslinking reaction is usually supplied by heat during stretching or heat setting.

For example, at 200°C for about 10 seconds, at 150°C for about 1
It may be heated for about 15 minutes at 120° C., about 8 seconds at 220° C., or it may be heated under harsher or milder conditions. The coating solution should be dried at 100°C.
for about 5 seconds.

It may be heated at 110°C for about 5 seconds and at 90°C for about 20 seconds. It may also be air-dried.

Oriented crystallization conditions of polyester film, e.g. stretching,
Conditions such as heat fixation can be carried out under conditions conventionally accumulated in the art.

The light transmittance of the film thus obtained is 80% or more at a wavelength of 550° C.m. The light transmittance of the film depends on the light transmittance of the base film because the primer layer is extremely thin.

The polyester film of the present invention is UV ink.

It exhibits extremely high adhesion to hard coat paints, gelatin compositions, etc., has high transparency even in thick pastes, does not cause adhesive blocking, and has good lubricity, making it easy to handle.

<Example> The present invention will be further explained below with reference to Examples.

Note that "parts" in the examples mean "parts by weight." Moreover, each characteristic of the film was measured by the following method.

1. Apply the evaluation paint to the adhesive primer-coated polyester film, and after drying, make scratches with a K blade at intervals of 1 m, apply adhesive tape, and then peel it off rapidly.
The number of stitches X that remained without peeling out of 00 pieces is expressed as /100.

2. Surface roughness Ra (Center Line Ave
rage: Center line average roughness) According to JIS BO601, using a high-precision surface roughness meter 5E-3FAT manufactured by Koita Research Institute, the needle radius was 2μ.
m, load 30TR9, magnification 200,000 times.

Hang the chart under the condition of cutoff 0.08 vnx, extract a part of measurement length L from the film surface roughness curve in the direction of its center line, and connect the center line of this extracted part to the X axis and the direction of vertical magnification. is the Y axis, and the roughness curve is Y =
When expressed as f (X), the value given by the following formula is μ
Expressed in meters.

Ra= (l/L), /' oL□ f(x) ld
x For this measurement, the reference length is 1.25 parts M, and 4 pieces are measured.
Expressed as an average value.

3. Film friction coefficient (film slippery) AS
According to TM D 1894-63, the coefficient of static friction (μ3) between the coated surface and the polyethylene terephthalate film (non-coated surface) is measured using a slippery measuring device manufactured by Toyo Tester Co., Ltd. However, the thread plate shall be a gas plate and the load shall be 1 kp.

4. Light transmittance The absorbance of one film was measured using a visible light spectrophotometer, and the light transmittance at a wavelength of 550 nm (shown as @).

Example 1 Aqueous polyurethane dispersion with carboxylic acid amine base [
80 parts (as non-volatile component) of Toyo Polymer ■ (product name: Merci 545), 10 parts of polyoxyethylene nonylphenyl ether (product name: NS-240, manufactured by NOF ■), polyfunctional epoxy compound [Toyo Polymer ■: 10 parts of Merci (trade name: AD-C-65) and 3 parts of a catalyst (Toyo Polymer (trade name: ADCP)) were diluted with ion-exchanged water to prepare an aqueous primer coating solution with a solid content concentration of 2% by weight.

This coating solution was applied by gravure foot method to one side of a 125 μm thick biaxially stretched polyethylene terephthalate film with a center line average roughness Ra of 0.007 μm and no added lubricant, and then heated at 142° C. for 45 seconds. After heat treatment, a primer-coated polyester film with an average coating weight of 55 da(dry)/i was obtained.

Table 1 shows the properties of the obtained film.

Example 2 Intrinsic viscosity measured in 0-f20 phenol at 25°C!
o, 63 polyethylene terephthalate (containing lubricant: calcium carbonate) was melt-extruded onto a rotating cooling drum maintained at 20°C to obtain an unstretched film with a thickness of 1.7 NTR,
Next, after stretching the film 3.6 times in the machine axis direction, a coating solution identical to the coating solution prepared in Example 1 was applied to one side of the uniaxially stretched film by a kiss coating method. The average coating rate at this time was 50~/+rt' in terms of solid content.

Subsequently, it was stretched 3.8 times in the transverse direction FC at 105°C, and further stretched 2 times in the FC direction.
A biaxially oriented polyester film coated with a primer on one side and having a thickness of 125 μm was obtained by heat treatment at 05°C. Table 1 shows the properties of the obtained film.

Example 3 Adipic acid, instead of the polyurethane aqueous dispersion of Example 2,
An aliphatic polyester with an OH value of 53 consisting of sebacic acid, 1,5-bentanediol, and neopentyl glycol components, hexamethylene diincyanate, 7-minoethanol sulfuric acid half ester, and potassium hydroxide contains 10 SO in the molecule. , base 2. A primer-coated polyester film was obtained in exactly the same manner as in Example 2, except that 80 parts of an aqueous polyurethane dispersion (as a non-volatile component) having a solid content ratio of zwt% was used.

Table 1 shows the properties of the obtained film.

Example 4 Except that instead of the coating liquid of Example 2 ((Polyurethane dispersion containing carboxylic acid amine base [manufactured by Inu Nippon Ink Industries ■: trade name] Idran HW-, 1,00) was used,
A primer-coated polyester film was obtained in exactly the same manner as in Example 2. Table 1 shows the properties of the obtained film.

Comparative Example 1 For comparison, various evaluations 2 were conducted using a 125 μm thick lubricant-free polyethylene terephthalate film that was not subjected to primer treatment. The film percentage properties are shown in Table 1.

Comparative Example 2 Using only 90 parts of the aqueous polyurethane resin of Example 1 and 10 parts of polyoxynonylphenyl ether, a polyester film having a ply and a matrix layer containing no aqueous epoxy resin as a crosslinking agent and a catalyst was prepared by the method of Example 1. Obtained. The properties of the obtained film are shown in Table IK.

The looomp-le film of Example 2 was heated at 60°C and 80%
R) When left for 24 hours under the following conditions, a slight blocking phenomenon occurred.

Claims (1)

[Claims] 1. A primer made by crosslinking aqueous polyurethane with an epoxy compound having two or more epoxy groups on at least one side of a polyester film having a center line average roughness (Ra) of 0.02 μm or less. Light transmittance with layer (550
A highly transparent and easily adhesive film with a nm) of 80% or more. 2. The highly transparent and easily adhesive film according to claim 1, wherein the polyester film has a centerline average roughness (Ra) of 0.015 μm or less and a thickness of 25 to 300 μm. 3. Before crystal orientation is completed, at least one side of the polyester film is coated with an aqueous primer coating solution containing polyurethane and an epoxy compound having two or more epoxy groups, and then dried, stretched, and heat treated to achieve crystal orientation. A method for producing a highly transparent and easily accessible film, characterized in that the center line average roughness (Ra) is 0.02 μm or less and the light transmittance (550 μm) is 80% or more.