JPS6076340A - Easy adhesive polyester film - 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 The present invention relates to a surface-coated polyester film having an easily adhesive interface. More specifically, the primer scatters and adheres to the surface in a granular state, creating an easily adhesive interface that provides not only close contact between the base material and the granular primer but also a wide range of adhesion between the coating layer of the top coat material. The present invention relates to a polyester film having the following properties.

Polyesters synthesized from aromatic dibasic acids or their ester-forming derivatives and diols or their ester-forming derivatives, such as polyethylene terephthalate or copolymers thereof, polyalkylene naphthalates, and also this polymer and small proportions of other resins. It is well known to melt-extrude a blended product with the above to form a film. This biaxially stretched polyester film has better heat resistance, gas barrier properties, electrical properties, and chemical resistance than films made of other resins. However, since the surface is highly crystal oriented, the surface has high cohesiveness and poor receptivity to paints, adhesives, and inks.

Therefore, when forming a synthetic resin layer on the surface of a polyester film, in order to strengthen the adhesion between the two, the substrate surface must be subjected to corona discharge treatment, ultraviolet irradiation treatment, plasma treatment, or flame treatment to activate the surface and then synthesize the resin layer. A means of coating with a resin coating has been applied.

However, although these methods of activating the substrate surface can be expected to improve adhesion to the coating material layer by increasing secondary bonding force due to wetting, the activation rate decreases over time and surface treatment The adhesion force obtained is not necessarily satisfactory and cannot be a sufficient means.

Other methods to increase the receptivity of polyester film surfaces include etching, which involves swelling or partially dissolving the surface with various agents; This method is based on the principle of etching the surface by dipping it in a chemical to relax the crystal orientation near the surface, while at the same time reducing the cohesiveness and increasing the adhesion of the binder resin. It is the most reliable, and the adhesion between the base material and the synthetic resin coating layer provided thereon is strong.

However, some of the chemicals used in this method are harmful, making handling dangerous and requiring extreme care to prevent environmental pollution from being released into the atmosphere. There are disadvantageous issues.

In addition, when coating and impregnating these, rusting of equipment and machinery, etc.
Not only is this accompanied by corrosion, but the processing solution may remain in the substrate film after processing, and over time may leach out and have an adverse effect on the upper coating layer. Therefore, this type of technology is gradually disappearing.

As a further development of this method, there is a method in which a single layer of primer (undercoat layer) is spread over the base material in advance to form a thin surface layer that is different from the base material, and then a desired synthetic resin hh layer is coated. . When forming the undercoat layer, the coating process is generally performed in a process separate from the film forming process, so there is a risk that dust such as dirt and debris may be mixed in during the process. For this reason, it is necessary to maintain the delicate quality of highly processed film products such as audio magnetic tape, video magnetic tape, computer magnetic tape, X-ray photographic film, printing photographic film, diazomic film, etc. Even if an easily adhesive interface is successfully formed, the base film cannot be used in applications where surface defects are caused by dust. In particular, when finishing the base film into the desired processed product, in order to modify the surface to be highly processable,
Providing a step of primer coating lacks rationality and cannot be said to be advantageous from an economical or industrial technical point of view.

Therefore, if the undercoating process is carried out in an atmosphere that is as dust-free as possible, i.e. in the sequence of polyester film production, it will be possible to fully support the use of the above-mentioned advanced film processing products. Become. Therefore, it is desirable to perform subtraction processing in an inline process.
In the prior art, the formation of an easily adhesive interface by primer coating on the surface of a polyester film has been mostly achieved by coating the surface layer with a composition dissolved in an organic solvent. Therefore, if this method is attempted during the film forming process, the surrounding organic solvent gas will volatilize, creating an environment that is unfavorable from a safety and hygiene perspective.
There are rumors that major equipment related to film production must be made explosion-proof. Therefore, although it is theoretically possible to incorporate undercoat treatment in-line, in practice it causes numerous problems and in reality, the process must be done offline.Moreover, the primer coating As for the effect of surface modification itself, even if conventionally known primers are highly effective for a specific topcoat composition, they are not effective for others, so it is unlikely that they will be sufficiently satisfactory over a wide range of areas. It is difficult to say that there is a material that has a surface receptivity.In addition, applying a primer coating, even if the amount is minimal, prevents the formation of a flat thin film on the surface layer. The weir handling is significantly impaired, so-called slippage becomes poor, and wrinkles are likely to occur.For bases such as those for magnetic tapes whose surface is made as flat as possible to improve electromagnetic properties,
This tendency is especially remarkable, and 6
- Not only is it extremely difficult to wind up and unwind, but if left untreated, a sticky blocking phenomenon occurs, which is extremely difficult to avoid unless the surface of the pace is extremely roughened.

An exception to this is when the primer coating is performed in a continuous process prior to the final desired coating, such as a magnetic coating or a photographic emulsion coating, in which case this type of blocking and handling problem can be avoided; Disadvantages that are unilaterally imposed only on those in a position to perform continuous coating, such as improvements and modifications to equipment that can perform continuous coating, and the hardships of maintaining two continuous processes in good condition at the same time, when one of the processes is in poor condition. Considering losses due to decreased yield, etc., even if it seems efficient, the actual economic burden is extremely large. For example, in the case of a polyester film with a thickness of 25p or less, which is a flat paste for magnetic tape with a center line average roughness (Ra) of less than 0.015μ, for the reasons mentioned above, a primer coat is applied before applying the magnetic paint. It is difficult to do this unless you use a means to do this, and it is difficult to do this in the form of an independent primer coat, or the film material provider should share this responsibility and provide the user with an easy-to-adhesive film with a primer foot. is extremely difficult.

In general, when a film is used as a roll, its transportability, handling, ease of handling, blocking properties, etc. are determined by the slippery properties of the contact surfaces of the film, or by the transport system during film formation. Frictional behavior at each contact point plays a large role, and in order to keep this low, it is necessary to reduce the adhesive shearing force unique to the base film substrate, or to maintain the Young's modulus of the polymer material at a high level during pressure bonding. Alternatively, it is known in principle to form minute protrusions on the surface to reduce the contact surface area. However, if a primer is formed that is compatible with the polyester film,
Since most of the thin film exhibits flat characteristics, it is difficult to reduce the coefficient of friction for the reasons mentioned above unless the base is roughened to a large extent and contributes to reducing the contact area. In other words, in order to reduce the coefficient of friction and ensure ease of handling, it can be said that an effective measure is to reduce the adhesive shearing force at the surface layer interface or to reduce the surface contact area. In order to reduce the adhesive shearing force, it is possible to add organic lubricants and oils and fats to the primer, which are also effective in preventing blocking. In addition, in order to make the contact area relatively small, small particles that form protrusions on the primer layer, for example, C.
It is preferable to add aCO3, Mg0TIO, ZnO, etc. so that a small amount of air exists between the contact layers. Even if the primer is pulled out skillfully, there are still problems such as the adhesion between the important primer layer and the base paste being significantly weakened, or the original primer effect not being fully expressed.1. is almost impossible for the reasons mentioned above.

In view of this, the inventor has proposed that blocking is less likely to occur,
In addition, as a result of intensive research aimed at providing a polyester film that is particularly suitable for use with magnetic tapes, the 9-film was selected as a primer-coated polyester film that has excellent transportability and ease of handling. The composition is applied under specific conditions, the primer is scattered and fixed on the entire surface in the form of particles, and the center line average roughness (Ra) is maintained within a range of not exceeding 0.05μ, and the proportion of the total surface area is projected. It was discovered that a film maintained at an area of 1% or more could completely achieve the object, and the present invention was achieved.

Aspects of the present invention will be successively explained below.

The composition selected in the present invention is a mixture consisting of one or more types of water-dispersed polymer liquid and a surfactant, and it is preferable that the film forming temperature of the polymer is rather high.
As a tentative standard, a temperature of 40°C or higher is desirable. On the other hand, the specific conditions for applying the composition require a series of steps such as applying the composition to the polyester before completing crystal orientation, and then completing biaxial stretching and oriented crystallization. The temperature conditions are as follows: lateral stretching temperature: 75°C to 120°C, crystallization temperature: 180°C.
It is necessary for the coating material U to undergo a heat history of ~245°C.

By combining these conditions, a single layer of primer can be scattered and fixed to the film surface extremely uniformly in the form of particles. In this way, the main aim of the present invention is not to simply form a single layer of primer on the substrate as a flat film (the main aim of the present invention is to make the primer itself into particles under special conditions and fix it in order to develop easy adhesion. This method is completely different from the conventional method in which an inorganic filler, for example, is added to a single layer of primer, and the friction coefficient is reduced by reducing the contact surface area by the protrusions.

Applicable primers include water-dispersed acrylic resin and vinylidene chloride/PVC copolymer.

Examples include acrylic styrene resin, epoxy resin, polyurethane resin, among others, film forming temperature,
Polyurethane dispersions with a relatively high melting point and a large Young's modulus are preferred. If the film formation temperature drops significantly below 40° C., the resin may melt at the high temperatures encountered during film formation, potentially resulting in a flat film. Furthermore, if the Young's modulus of the resin film itself is too low, even if it is possible to form a single layer of granular primer, the result will be unfavorable in terms of slippery properties and blocking.

In this sense, it is preferable that the resin film has a microhardness meter (Shore A) of 40° or more in order to fully implement the present invention.

The polyurethane may be aromatic polyurethane or aliphatic polyurethane as long as it satisfies the above conditions, and its types include polyester type, polyether type, or ionic, i.e. anionic, type to enable water dispersion.1. It may be of any cationic type. Usable products include Sunbren UX-3500 (Sanyo Kasei Q Softex U-Zoo), UE-296A (chemical soap),
Bathcoal V-217 (Kaisei Chemical Industry).

Rethermin W-10200 (Dainichiseika), Impranil DLN■ (Bayer), Impranil DLH■ (Bayer), HydraKariju-140■ (Inu Nippon Ink),
Eiserak S-4040■ (Nudugaya Chemical) tc can be cited as an example.

The various resins to be used as primers as described above may be used alone or in a mixture of two or more without any problem, as long as the purpose of the present invention is not significantly impaired.

There is also no problem in adding a small proportion of a surfactant to the primer of the present invention in order to maintain a better painted surface appearance or to improve the wetting properties of the primer surface. Further, in order to improve the performance of the coating film properties of the primer itself, for example, a crosslinking agent or a crosslinking accelerator may be added, as long as the above-mentioned purpose is not hindered.

As mentioned above, the granular primer of the present invention is different from the conventional concept of covering the entire surface of the base film with a thin film, but in terms of effectiveness, it is necessary to cover 1- or more of the total area (projected area ratio). If it is occupied by granular primer 13-, it will be fully effective.

If it is less than 1 inch, the effect may be zero, but it is rather insufficient and deviates from the purpose of the present invention.

In order to explain the present invention in more detail, one example will be described below, but this is an illustration and is not limited thereto. Note that the measurement items in the examples were measured by the following methods.

1 Adhesive Primer Coating Treatment The polyester film was coated with various top coats under specified conditions, and Scotch tape Ji600 (manufactured by Three Hachi Co., Ltd.) width 19 + 4 m was applied.
/ m *Length 8 cIn was pasted without air bubbles, and the top was leveled with a manual load roll as described in JISC2701 (IT 5), and the pasted laminated part 5m was used with Toyo Seiki Co., Ltd. Tensilon. At a head speed of 300w/min,
This sample is peeled off in a T-shape, the peel strength at this time is measured, and this is divided by the tape width to obtain y/cm. In T-shaped peeling, the laminate was placed with the tape side facing down, and the distance between the tension chucks was 514 m.

2. Surface slipperiness The coefficient of static friction was measured on the primer-coated surface and the non-coated surface at a temperature of 20° C. and a humidity of 60% RH using a sliver measuring tester manufactured by Toyo Tester Co., Ltd.

3 Blocking resistance Two films (5 cm x 5 cm) are pasted together on the coated surfaces, and the thickness of the film is Vc6 x 6 cm.
m silicone rubber, followed by the same dimensions and thickness 3m/m
A glass plate is sandwiched from both sides, and this weighs lc2Kg.
24 hours in an atmosphere of 40℃ x 75cmRH with a load of
After being released, the film surfaces were peeled off from each other, and those that were completely peeled off were marked with ○, those with surface defects caused by adhesion on either side were marked with ×, and those with slight defects were marked with △. .

4 Center flatness roughness Ra) Stylus type surface roughness meter manufactured by Tokyo Seimitsu Co., Ltd. (Sarfeom8B)
With a needle radius of 2 μ and a load of 0.19 gr, the standard length direction of the film was set at 50 m with respect to the film standard length of 26 m/m.
Magnify 20,000 times in the surface roughness direction and plot the roughness curve. A part of the reference length 211) was cut out along the measurement length in the direction of the center line, and the roughness curve was expressed as Y = f(x), with the center line of this cut out part being xh and the direction of vertical magnification being Y-. The value given by the samurai's formula is expressed in μ.

The reference length for this measurement is 0.25 M, and eight measurements are taken, three from the direction with the largest value are excluded, and the average value of the five is expressed.

5. Particulate primer occupancy. The entire field of view that can be observed from a photograph at an appropriate magnification using a differential interference microscope or a scanning electron microscope.

When Vn is the area of the uncoated portion in which no particulate matter is formed, the particulate primer occupancy is expressed by the following equation.

Example 1 Using orthochlorophenol as a solvent, 0.125 wt.
．． 1 of polyethylene terephthalate containing 15 wt%
Dry at 60°C, melt extrusion at 284°C, rapidly solidify on a casting drum held at 50.4°C 160°C
An unstretched film of μ was obtained. Immediately after stretching to 3.6 times in the longitudinal direction, that is, immediately before the preheating zone where the single-motion stretched film moves to the next processing, an aqueous dispersion coating solution with a total solid content of 2 wt % is applied using the usual p-ru coating method. One side of it was coated.

The solid content of the coating liquid consists of the following types, and all numbers indicate weight ratios.

Polyvinylidene chloride resin (trade name: Saran EX 2380, non-chemical) 30 Polytechnoxy compound (trade name: EX 314, Nagase Sangyo) 30 Polyethynimine 17- (trade name: p-1ooo, Nippon Shokubai) 30 Surface activity Agent (product name: NS 206/NOF) 10 times 9
It was roughly dried in a preheating zone of 0 to 95°C, then laterally stretched to 3°51 times, and then heat-set at 210°C for 7.7 seconds. In the end, a base film of 15μ was obtained, but the coating amount was 0.03 f/m" (Dry). The scattering of particulate matter could be confirmed from the photograph. The characteristics of the obtained film were summarized as follows. As shown in Table 1f1 below, it can be seen that the basic properties are not different from the uncoated film which is not treated at all under the same conditions, and a good adhesion effect is exhibited.

18-Table 1 Regarding adhesion, the magnetic coating prepared as described below was applied to each film after calendering to a thickness of 5 μm, and the peel strength of the coating was measured.

[Preparation of paint for evaluation]

Nitrocellulose R8I/2 for paint lacquer thinner
(Flakes containing 25 pieces of Impropa Tool Daicel■
Prepare a 40wt solution by dissolving 43.
8 parts, followed by Polyef, Chill resin (Desmoreene 170
0 Bayer M) a 2.5 parts, Nikai chromium powder 2
As a dispersant/wetting agent, soybean oil fatty acid (Legion P manufactured by Riken Vitamin ■), cationic activator (Cation AI4 manufactured by Nippon Oil & Fats ■), and squalene (shark liver oil) were used at 1 part, 0.5 part, and 0 parts, respectively. Add 282 parts of a mixed solvent consisting of methyl ethyl ketone (hereinafter abbreviated as MEK) / cyclohexanone / toluene - 3/4/3 (weight ratio) to a ball mill. h) Prepare this mother liquor 50
1 part, 48 parts of an addition reaction product of trimethylolpropane and toluylene diisocyanate () ρ Natere: manufactured by Nippon Polyurethane Kogyo ■) and 6.25 parts of butyl acetate were added.
Final) C42, 75 wt% magnetic paint for evaluation was prepared.

Example 2 Under the same film forming conditions as in Example 1, in-line coating was performed by replacing the coating liquid composition with the one shown below.

The solid fraction ratio is as follows: N-β (aminoethyl) r-aminopropyltrimethoxysilane (SH6020: Toshi Silicon): 3ON-methylacrylamide (Soken Chemical): 3ON-methylol acrylamide (Torezin F30 Teikoku Chemical) )=10 diphenylmethane-P-diethylene urea (mutual M engineering)
= 20 Surfactant (N8208 Nippon Oil & Fats): 10 Total solids concentration was 2 wt water dispersion.

The final film has o, o a5t/m'(
It was confirmed from the photograph that the particulate matter was evenly distributed. This is shown in Figure 1.

It was found that the polyester film on which this type of granular primer is formed has significantly improved handling properties (equivalent to that of the uncoated polyester film obtained under the same conditions), and has significantly improved adhesion properties. This is shown in Table-2.

The primer occupancy rate was 5.3%, and b was 0.02.
It was 0.

Table 2 The adhesion (1) was evaluated using the same method as described in Example 1, and the adhesion (n) was evaluated using cellophane printing ink (CL -8709 white) stock solution 1 to Mli:/) toluene/ethyl acetate = 1. / 1/1 mixed solvent was diluted at a ratio of 2 parts to prepare a paint for evaluation. Dainippon Ink (trade name) 22 - The coating thickness was determined using gravure caulk, 2.1μ was applied under the same conditions, and the peel strength was determined using a predetermined method.

Comparative Example 1 Sufficient film formation was observed even when left at room temperature, and the hardness of the formed film was 40° using the Shore A method.
A water-soluble copolymerized polyester (Isresin 2000: Takamatsu Yushi) containing a large amount of water and a methylolated melasin resin (Sumitex Resin M3) for hardening it.
All other film forming conditions were the same as in Example 1, except that the solid content ratio (weight) of Susumu Chemical) and surfactant (NS208 NOF) was replaced with a 2 wt% aqueous solution with a concentration of 80:10:10. In-line coating was performed to form a primer on the surface. As a result, although it was possible to wind the film, the slipperiness of the film itself was greatly reduced, some wrinkles appeared at the edges, and the film could not be completely rolled. The primer effect of this film was found to be sufficient compared to the uncoated film, but as a result of examining the surface using differential interference microscopy, it was clear that the primer was formed as a flat thin film, causing slippage problems. It became.

The erasability (static friction coefficient) of coated/uncoated surfaces is 1.0.
It was confirmed that the film was an easily adhesive film that was extremely difficult to handle, making it difficult to put it to practical use.

Comparative Example 2 In Example 1, the crystallization heat treatment temperature after lateral stretching was changed to 164
℃, and the processing time was increased from 7.7 seconds to 8.8 seconds, and in-line coating was performed with the same coating liquid composition.
Although the formed primer is partially granular, it loses its shape in some places, and there are parts that are exactly the same as the base material and parts that look like dusty surfaces, and the coefficient of static friction is low. It was found that the value had increased to 0.57. However, regarding the primer effect, adhesiveness (1
), there were no problems with gold (at the same level as in Example 1), but the fact that the shape of the primer layer was non-uniform left concerns from a quality standpoint and could not be used.

Example 3, 4.5 Titanium oxide with an intrinsic viscosity of 0.63 and a particle size of 0.3μ measured at 35°C using orthochlorophenol as a solvent was
Polyethylene terephthalate containing 0.25 wtl was dried at 167°C and melt extruded at 287°C -47.8°C.
An unstretched film with a thickness of 152 μm was obtained by rapidly cooling and solidifying it on a casting drum held in the film, and then this was stretched by 3.6 times in the longitudinal direction on a heated metal roll at 93° C.
After this, A3. by the usual method. /K 4. A5. In-line coating was performed successively with the coating liquid of
Stretching was performed by 3.5 times. Then, after heat fixing at 231° C. for 7.4 seconds, it was wound around a core to create four types of samples including a non-coated sample. A summary of the properties of the obtained film is shown in Table 3.

26- -27- The corresponding uncoated films of Examples 3 and 4.5 showed an extremely low adhesion I of 10.79/cm formed as granules, and the primer had an adhesion-promoting effect. was found to be sufficiently expressed.

[Brief explanation of the drawing]

FIG. 1 is a 900x differential interference interference M micrograph showing an aspect of Example 3, showing that particulate matter is scattered on the surface. -K 1 Written amendment to legal proceedings dated 2nd July 1982, Commissioner of the Japan Patent Office 1, Indication of the case, Patent Application No. 184481 2, Name of the invention, Easy-adhesive polyester film 3, Person making the amendment Related Patent Applicant Representative Sa Okamoto Contents of the amendment in Column 6 of "Detailed Description of the Invention" in Part 4 of the Specification (1) On page 3, line 15 of the specification, the [ni-bj] is replaced with "
is corrected to "most". (2) On page 6, line 15 of the same book, there is a 1
amended to "to form". (3) On page 9, line 12, the phrase ``ultimately easy'' is corrected to ``ultimately easy''. (4) On page 23, line 8, [2000J is 1'4]
Corrected to 000J. (5) Table 3 on page 27 has been amended as shown in the attached sheet. that's all

Claims (1)

[Claims] Particulate matter is scattered and fixed on the surface of the polyester film, and its proportion to the total surface area is 1 inch or more in terms of projected area, and the surface roughness in this state is 0.05 μ in center line average roughness (Rh). Brimer-coated, easy-to-adhesive polyester film.