JPH0561294B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a polyester molded article with good adhesiveness, and more specifically, a technique for changing the atomic composition of the surface layer of the molded article by corona discharge treatment while transporting the molded article. The aim is to obtain a polyester molded product with excellent adhesive properties by appropriately adjusting the adhesive properties.
Surface modification of plastic molded articles by corona discharge is generally known as a surface treatment technique for plastic films, and has had substantial effects such as improved adhesion due to surface activation. However, the results are not completely satisfactory. The present inventors have focused particularly on polyester molded products, and have found that, for example, when subjecting a polyester film to corona discharge treatment to improve its surface (particularly to improve adhesion), the treatment efficiency is sufficiently satisfactory at the actual production level. I decided to establish a method that would allow me to obtain this. As a method for corona discharge treatment of plastic moldings, for example, as shown in Japanese Patent Publication No. 17747/1982,
Although there is a technique for promoting chemical changes on the discharge surface by supplying an organic solvent to the discharge section, it is difficult to apply this technique to molded products where residual solvent may be a problem. Also Journal of Applied
Polymer Science, Vol.15, p.1365-1375 (1971)
describes a technique in which corona discharge treatment is performed in an inert gas atmosphere, and suggests that differences in treatment atmosphere may have an effect on activation or deterioration. Based on this, techniques have been proposed in which processing is performed by replacing the atmospheric atmosphere with, for example, a low-oxygen atmosphere. However, the implementation techniques that have been proposed so far have various drawbacks as described below. For example, the method disclosed in Japanese Patent Application Laid-Open No. 55-50034 is
The chamber that covers the entire film running space, including the plastic film unwinding reel, take-up reel, and the corona discharge treatment device installed between them, is regarded as one closed space, and the entire atmosphere of the chamber is controlled. This is what we are trying to do.
Therefore, a large amount of inert gas is required, and a special sealing mechanism is required to make the chamber itself airtight, which makes the apparatus complicated and these factors raise the cost. Therefore, as a practical problem, a sufficient inert atmosphere cannot be guaranteed, and it has not yet been possible to freely control the gas composition on the outermost surface of the film. Furthermore, Japanese Patent Application Laid-Open No. 57-23634 discloses that a hood covering the corona discharge atmosphere (hereinafter referred to as the first hood) is provided to locally control the atmosphere, and another hood (hereinafter referred to as the first hood) is provided in front of the first hood. A control method is disclosed in which a second hood) is provided and an inert gas is sprayed onto the traveling film in the second hood. However, with this technology, for example, in Example 2, ``from the slit provided at a 45° angle from the bottom of the pipe toward the film inlet side.''
Supplying CO ₂ into the hood (Note: 2nd hood)
configuration is recommended. From this explanation, it is clear that the inert gas is intended to be supplied into the second hood, and that the gas blown out from the slit hits the inner wall of the second hood and diffuses into the second hood. It is clear that the inert gas is filled inside the hood and covers the film surface, and the publication also states that it is best to avoid blowing out inert gas from directly hitting the discharge electrode, and that the inside of the first hood is It states that the supply of inert gas may be stopped once the gas atmosphere has been replaced with inert gas, and the second hood is expected to play a supplementary role to the first hood. It is clear that it is nothing more than Therefore, this method is more realistic than the technique of replacing the entire atmosphere inside the chamber with an inert gas, but
The studies have only been conducted from the perspective of controlling the entire atmosphere inside the hood, and there is no concept of focusing on the outermost surface of the molded product, which is the most important for corona discharge. Furthermore, in JP-A No. 56-49737, a technique was started in which drying gas is blown into the hood in order to prevent outside air from entering the corona discharge atmosphere.
However, with this technology, the intention is only to suck out the wet gas in the hood and introduce dry gas to perform gas replacement, so to speak, and there is no concept of applying a spot to the outermost surface of the molded product. . The reason why conventional improvement processing methods cannot achieve sufficient results can be considered as follows. In other words, the results of corona discharge appear on the outermost surface of the molded product, and therefore, although the gas composition at the outermost surface of the molded product is important, conventional improvement methods simply treat the entire inside of the processing system or chamber. It is only recognized that controlling the gas atmosphere is sufficient, and there are also obstacles caused by the accompanying flow (outside air) on the surface layer of the molded product that is carried in while traveling, that is, the overall gas atmosphere inside the chamber and the molded product. This seems to be because differences in the gas composition covering the outermost surface are not taken into consideration. If processing is carried out in a batch-type stationary state, the above-mentioned obstacles will not be a problem, but this will significantly reduce industrial productivity and increase market prices, so in the end it will only be used for a limited number of purposes. It cannot be put into practical use. On the other hand, in order to obtain the desired processing effect in the continuous production system as described above, the processing speed must be considerably low, but this will damage the surface of the molded object and cause poor appearance. Problems such as poor adhesion and increased blocking arise. In conventional corona discharge treatment under atmospheric conditions, the surface of the molded product undergoes oxidation and an oxidized deterioration layer is formed on the surface, so even if the degree of corona discharge treatment is increased, the adhesion cannot exceed a certain level. It cannot be improved. The inventors of the present invention have been concerned about this situation for some time and have conducted various studies. As a result, nitrogen gas,
Or mainly nitrogen gas with oxygen content of 20% by volume.
When a nitrogen-containing composition gas with the following composition is continuously sprayed from the bottom of the discharge side electrode onto the treated surface of the workpiece, the amount of oxygen gas on the surface of the molded object becomes extremely small, and the effect of the nitrogen gas is mainly directly affected. This led to the completion of the present invention after discovering that the desired treatment effects could be obtained. The reason why the corona discharge surface becomes strongly influenced mainly by nitrogen gas when nitrogen gas or a nitrogen-containing composite composition gas with an oxygen content of 20% by volume or less is sprayed cannot be fully elucidated. Although not, you can think of it as follows. That is, the surface of the molded product transferred to the corona discharge section is accompanied by a considerable amount of air, although it varies depending on the surface characteristics and the transfer speed, and its composition is generally oxygen: 21% by volume, nitrogen: 78% capacity
It is. On the other hand, the composition of the entrained air on the surface of the molded product cannot be easily changed by the above-mentioned ordinary means, such as adjusting the atmosphere in the chamber, but when the above-mentioned blowing means according to the present invention is adopted, the blowing gas is Since part or all of the entrained air layer is expelled and replaced, the composition of the entrained air layer changes.
This change is due to air containing 21% oxygen being replaced by blown gas containing less than 20% oxygen, so the oxygen concentration decreases relatively and the effect of nitrogen gas, which is present as the main component, is reduced. On the contrary, it increases, and an effect that cannot be obtained by conventional corona discharge treatment under an atmospheric atmosphere is exhibited. As mentioned in the above discussion, if the nitrogen gas or oxygen content is
The point is that a composite composition gas containing 20% by volume or less of nitrogen is continuously sprayed from the bottom of the discharge side electrode onto the treated surface of the molded product, so gas components other than oxygen and nitrogen include: argon gas,
Regardless of whether it is helium gas, carbon dioxide gas, etc., the influence of nitrogen gas will be significant in any case. When we attempted to apply the improved corona discharge treatment technology to polyester molded products as described above, we found that there were no inconveniences in terms of blocking or slipping, and the adhesion was significantly improved. It was confirmed that the adhesiveness did not deteriorate even under high temperature and high humidity, and the present invention was completed. That is, the gist of the present invention resides in the following points. A polyester molded product composed of dibasic acid residues of which 80 mol% or more is terephthalic acid and glycol residues is continuously transferred to a corona discharge treatment device comprising at least one pair of electrodes facing each other. When performing corona discharge treatment, nitrogen gas,
Or mainly nitrogen gas with oxygen content of 20% by volume
The following nitrogen-containing composite composition gas is sprayed onto the corona discharge treated surface of the molded product, and during the spraying, the gas is continuously sprayed from the side of the discharge side electrode facing the molded product along the discharge generation direction. By spraying the molded article, the accompanying air layer carried into the corona discharge treatment apparatus along with the transfer surface of the molded article is destroyed and dispersed and replaced with the blown gas, and the outermost surface of the molded article surface is destroyed and dispersed. from
When the amount of change in the oxygen index and nitrogen index in the thin layer portion within 100 Å from before corona discharge treatment to after corona discharge treatment is defined as Δoxygen index and Δnitrogen index, the ratio between the two [Δoxygen index/Δnitrogen index] index]
1.5 to -3.5, and the nitrogen index after corona discharge treatment in the thin layer portion is 3 or more. Note that the oxygen index and nitrogen index are determined by the following method. i.e. ESCA spectrometer ES
-200 model (manufactured by Kokusai Electric Co., Ltd.), the integrated intensity was determined from the 1s orbital spectrum of carbon on the surface of the molded product, and the integrated intensity was determined from the peak corresponding to the binding energy of organic nitrogen from the 1s orbital spectrum of oxygen. The number of oxygen per 100 carbon atoms is determined based on the integral ratio, and this value is defined as the oxygen index. Regarding the nitrogen index, the number of nitrogen per 100 carbon atoms is determined by the same method, and this is defined as the nitrogen index. The polyester targeted by the present invention is a polyester composed of a dibasic acid residue (80 mol% or more of the dibasic acid is terephthalic acid) and a glycol residue. This dibasic acid residue is mainly a terephthalic acid residue, but other dibasic acid residues of up to 20 mol% include isophthalic acid, phthalic acid, adipic acid, sebacic acid, succinic acid, oxalic acid, etc. groups, and also residues of oxyacids such as p-hydroxybenzoic acid can be used.
In addition, glycol residues are ordinary alkylene glycol residues, such as ethylene glycol, propylene glycol, trimethylene glycol,
Examples include residues such as tetramethylene glycol, hexamethylene glycol, and cyclohexanedimethanol, but residues of ethylene glycol, tetramethylene glycol, and cyclohexanedimethanol are particularly practically used. A particularly useful polymer is polyethylene terephthalate or polytetramethylene phthalate. The molded products of the present invention are typically exemplified by films and sheets (hereinafter simply referred to as films), and are applicable to unstretched films, uniaxially stretched films, biaxially stretched films, etc.
Other molded articles include elongated articles such as fibers, pipes, tapes, woven fabrics, and nonwoven fabrics. When forming the molded article using the polyester, it may be manufactured from polyester alone, but other polymer components may be blended as long as it does not adversely affect the properties of the polyester molded article.
Generally, it is blended in an amount of 20% by weight or less based on the total weight of the composition. The polymer components that may be blended may be determined in consideration of the type and properties of the molded product. In addition to polymer components, stabilizers, lubricants, anti-blocking agents, anti-fog agents, ultraviolet absorbers, twist retardants, clarifying agents, antioxidants, light stabilizers, and antistatic agents are added based on the type and purpose of the molded product. The present invention may contain additives such as agents, dyes, and pigments, and all additives that do not adversely affect the implementation of corona discharge are included in the scope of the present invention, regardless of whether they are used alone or in combination. In producing polyester molded articles using a polyester composition made of the above-mentioned materials, it is sufficient to follow a known method for each molded article. will not deviate from the scope. Therefore, the method for producing the molded article may be freely selected, but since a typical molded article to which the present invention is applied is a film, the method for producing the film will be explained as follows. That is, an unstretched film is first formed by forming the above-mentioned composition raw material into a film by a normal polyester film forming method, such as a T-die method or an inflation method. If this is stretched uniaxially or biaxially, a film with satisfactory strength can be obtained. The corona discharge treatment described below may be performed as one of the entire film forming process at the latter stage of the stretching process, and in some cases, the corona discharge treatment may be carried out while the once-rolled product is being re-rolled. In some cases, a method of applying In the present invention, the above-mentioned polyester molded product is treated, and the molded product is continuously transferred to a corona discharge treatment device having at least one pair of electrodes facing each other for surface treatment. Nitrogen gas, or a nitrogen-containing composite gas that is mainly nitrogen gas and has an oxygen content of 20% by volume or less [specifically, a gas from which a suitable amount of oxygen has been removed from air, or a gas containing other than oxygen to air. with an appropriate amount of gas components added, or even N ₂ alone or with it.
A mixture of inert gas or ionic gas such as H ₂ , Ar, CO ₂ , Xe, Kr, CI ₂ , NH ₃ , NOx, etc. (hereinafter abbreviated as inert gas for convenience)] is added to the bottom of the discharge side electrode. Then spray continuously onto the treated surface. At the time of spraying, the gas is sprayed from the side of the discharge-side electrode facing the molded product along the discharge generation direction. That is, the direction of the blowing is an important point in the present invention, and by blowing the blowing gas from almost directly above the molded object, it becomes possible to destroy and disperse the entrained air layer. Further, it is desirable that the spraying speed be 1% or more of the transport speed (conveyance speed) of the polyester molded article. As will be explained in detail later, the relationship between the oxygen index and nitrogen index before and after corona discharge treatment in the thin layer within 100 Å from the outermost surface of the surface to be treated (the region that has an important effect on adhesion) is strictly specified. By doing so, it has extremely excellent adhesion to various materials (e.g., metals; various inks, especially cellulose-based inks, water-based inks, etc.; resins, such as vinylidene chloride alone or copolymers, functional group-containing resins, etc.). A polyester molded product can be obtained. The structure and effects of the present invention will be clarified below based on the drawings of the embodiments, but the structure and arrangement of the discharge side electrodes and the shape of the cover shown in the drawings are only representative examples. Since the above is merely an example of application to plastic film, it is within the technical scope of the present invention to change the design on the condition that it does not go against the spirit of these descriptions. FIG. 1 is a sectional view of the main parts showing the implementation concept of the present invention,
FIG. 2 is a perspective view showing a part of the discharge side electrode, in which 1 is a metal drum, 2 is an electrode cover, and 3 is a perspective view showing a part of the discharge side electrode.
Reference numeral indicates a discharge side electrode, 4 indicates a gas supply pipe, 5 indicates a gas outlet, and 6 indicates a running film. That is, the film 6 is introduced from the direction of the arrow B into the metal drum 1 rotating in the direction of the arrow A, and further travels in the direction of the arrow C. , applying a high voltage of several thousand to tens of thousands at a high frequency of several hundred KC/S between the metal drum 1 covered with polyester, epoxy resin, ceramic, chlorosulfonated polyethylene, EP rubber, silicone rubber, etc. Under the influence of the high-pressure corona thus generated, for example, in the natural atmosphere, ozone and nitrogen oxide are generated, producing carbonyl groups and carboxyl groups on the surface of the film 6, thereby polarizing the surface. On the other hand, in the conventional example, oxygen in the atmosphere generates oxidized deterioration products on the film surface that inhibit adhesion. However, in this example, the entire corona discharge atmosphere is shielded from the atmosphere by the electrode cover 2, and a slit-shaped gas outlet 5 is provided on the bottom of the discharge side electrode 3 and directed toward the surface of the film 6. Since the structure is such that the inert gas is sprayed almost vertically from the bottom surface of the discharge side electrode 3, the accompanying air layer covering the surface of the molded product is destroyed, and the air layer is controlled by the composition of the sprayed gas. The surface of the molded product is covered by the low-oxygen atmosphere (inside the electrode cover 2), which substantially reduces the oxygen content in the coating gas, thereby increasing the influence of nitrogen gas. As a result, the corona discharge effect on the surface layer of the film 6 is maximized. This situation will be explained in more detail as follows.
That is, on the surface of the film 6 that enters at a fairly high speed along the direction of arrow B, a small amount of entrained air layer is formed, and this can be removed simply by following the conventional method to completely eliminate the entire atmosphere of the corona discharge area. If only the active gas is substituted, the outermost surface of the film 6 remains in an atmospheric atmosphere. Therefore, in carrying out the present invention, inert gas is strongly blown onto the film surface from the direction shown in FIG. 3, and the entrained air layer 7 is destroyed and dispersed by the jet stream 8. Therefore, the gas composition in the accompanying air layer 7 on the film surface is changed to increase the proportion of nitrogen gas. In some cases, the surface can be almost completely replaced with an inert gas. The flow velocity of the jet stream 8 necessary to destroy and disperse the entrained air layer 7 to obtain the above effect cannot be determined uniformly because it varies depending on the shape and dimensions of the molded product, the speed at which it is carried into the corona discharge treatment equipment, etc. However, as a result of experiments, it has been found that it is most preferable to set the speed based on the speed of entry of the entrained air layer 7 (in other words, the speed of transport of the molded product). Since it is generally convenient for understanding that the gas blowing speed is expressed in seconds and the film transport speed is expressed in minutes, such a convention will be followed in the present invention. That is, it is desirable to continuously spray the gas so that the value of the blowing gas velocity expressed in seconds is 1% or more of the value of the transfer velocity of the molded article expressed in minutes, but preferably 10%. If the ratio is more preferably 40% or more, the entrained air layer 7 can be destroyed and dispersed to the extent that there is no substantial problem. The angle at which the ejected gas is blown onto the film can be freely selected depending on the effective angle. The speed at which the molded product is carried in is generally 1 to 500 m/min. By adopting such conditions, it becomes possible to destroy and disperse the accompanying air layer, and at the same time, it becomes possible to protect the vicinity of the corona discharge part with an inert gas atmosphere, as shown in Figure 1. The electrode cover 2 shown in 2 has a primary function of protecting the electrode 3 from mechanical impact rather than an atmosphere maintenance function, and a secondary function of suppressing the accompanying flow. . Therefore, when carrying out the present invention, the electrode cover 2 may be removed from time to time, but in order to suppress the consumption of inert gas, it is desirable to reconsider its function for maintaining the atmosphere. As shown in FIG. 4, if the lower end (film side) of the cover 2 is squeezed and the inert gas is introduced into the cover 2 from the conduit 10 at the same time, the gas will converge along the inner surface of the slope 9. The gas flows in the direction of the arrow as shown, and a gas curtain effect is exerted at the inlet of the cover 2. That is, the intrusion of the entrained air layer is blocked on the inlet side, and the existence value of the electrode cover 2 is further improved. Furthermore, as shown in FIG. 5, if the extension cover 11 is provided particularly at the inlet and brought close to the surface of the molded product, the extension cover 11 will be filled with inert gas leaking from inside the cover 2. Therefore, the accompanying air layer that entered from cover 11 also
As it progresses inside the cover 11, it is broken and dispersed little by little. Therefore, upon reaching the corona discharge atmosphere, the degree of substitution with the inert gas becomes extremely high, and the effects of the present invention are more significantly exhibited. When using the device shown in Fig. 5, inert gas can also be sprayed from the extension cover 11, and the spraying angle can be freely selected, but in any case, the inert gas can be sprayed directly at the film introduction part. is sprayed, so the destruction and dispersion efficiency for the accompanying air layer is extremely high. On the other hand, on the exit side of the film 6 (the right side in Fig. 4), the gas inside the cover 2 is discharged along with the traveling film 6, so the sealing performance or the mechanism for blocking atmospheric intrusion should be given as much consideration as on the entrance side. Although it is not necessary to do so, it is meaningful to take the same consideration as on the inlet side in terms of reducing the amount of inert gas consumed as described above. In order to achieve the above-mentioned sealing function on the inlet and outlet sides of the cover 2 to the minimum extent, the film travel speed must be at least 0.2% or more, preferably 10%.
It is desirable to release the film onto the film surface at a speed higher than that. Regarding the ejection speed of the inert gas, only the lower limit side has been described for both the gas ejection port 5 and the inlet/outlet of the cover 2, but there is no practical need to set an upper limit on the ejection speed, and it is based on economic efficiency and the required quality of the final product. It should be decided appropriately based on the balance. By setting the processing conditions as described above, the treatment effect of corona discharge can be enhanced and the adhesion properties can be greatly improved.・Considering that it was necessary to quantitatively understand the surface properties later on, we proceeded with further research. As a result, (1) the surface of the molded product
Ratio of changes in oxygen index and nitrogen index before and after corona discharge treatment in a thin layer within 100 Å [Δ oxygen index / Δ nitrogen index], and (2) corona discharge in a thin layer within 100 Å of the film surface. It has been found that by strictly controlling the nitrogen index after treatment, a high degree of adhesion can be guaranteed.
In other words, the above-identified facts are that for (1) above, [Δoxygen index/Δnitrogen index] will be 1.5 to -3.5, and for (2) above, that the nitrogen index after treatment will be 3 or more. By strictly controlling the processing conditions and processing atmosphere of corona discharge,
For example, it can dramatically improve adhesion to metals, various printing inks (especially cellulose-based inks and water-based inks, etc.), various synthetic resins such as vinylidene chloride homopolymer or copolymer resins, and functional group-containing resins. This will be explained in more detail below. First, a polyester molded product that satisfies the requirement of [nitrogen index ≧3] specified in the present invention can sometimes be obtained using conventional processing conditions, and can also be obtained by known corona discharge treatment in a nitrogen gas atmosphere. It is possible. However, as explained earlier, in order to ensure the above-mentioned high level of nitrogen index using the conventional method, which is intended for continuous processing at least, large-scale equipment is required, making it difficult to put it into practical use on an industrial scale. Ta. On the other hand, if the method of the present invention is adopted,
The nitrogen index can be easily increased to 3 or more with relatively simple equipment. On the other hand, there are also reports that the adhesion of plastic materials to various materials is simply determined by the nitrogen index determined by the ESCA method.
However, such reports capture only one aspect of the influence on adhesion. By the way, if you blend N-containing ingredients into the material, the nitrogen index will increase, but considering the fact that just mixing antistatic agents and lubricants, which are N-containing ingredients, will not improve the adhesion, but will actually decrease it. It is clear that a mere increase in the nitrogen index does not immediately lead to an improvement in adhesion. Therefore, we investigated other factors that affect adhesion and found the above [Δoxygen index/Δ
The value calculated by [Nitrogen Index] almost accurately represents the effect of corona discharge treatment, that is, the effect of improving adhesion, and products that have been treated such that this value is 1.5 to -3.5 have a high level of adhesion that meets the purpose. The fact that it works has been confirmed. By the way, even if the nitrogen index within 100 Å of the surface layer after treatment is 3 or more, [Δoxygen index/Δnitrogen index] is 1.5.
If it exceeds this amount, the corona discharge treatment effect will be insufficient and a high level of adhesion cannot be obtained. In this sense, it is essential to adopt the treatment method of the present invention and to control the treatment conditions so that the nitrogen index is 3 or more and [Δoxygen index/Δnitrogen index] is 1.5 to −3.5. Note that it was practically extremely difficult to reduce this ratio to less than -3.5. By the way, regarding [Δ oxygen index / Δ nitrogen index], oxygen atoms constituting polyester, oxygen atoms in other polymers that may be blended, or specific oxygen atoms in various additives are released and removed by inert gas. , or may be replaced and removed by nitrogen atoms in an inert gas, resulting in a negative value as described above. In this negative range, generally in the range of -1.0 to 0, favorable results can be obtained in that the change in adhesive strength over time is extremely small and the blocking resistance is improved. The present invention is roughly constructed as described above, and the corona discharge treatment conditions are specified, and the treatment effect is constantly grasped from the amount of change in the oxygen index and nitrogen index of the surface layer before and after treatment. It has become possible to reliably obtain polyester molded products with excellent adhesiveness to various materials. In particular, the effect of improving adhesion is exhibited even after long-term exposure to high temperature and high humidity, and the surface layer with improved adhesion is not easily peeled off from the base layer, so for example, molded When it is a film, there is no possibility that the above-mentioned surface layer will be transferred to the back side during winding and storage, and there is no fear that the printing ink will peel off when it is actually applied as a film package. Furthermore, since the adhesion to other film base materials is improved, there is no possibility that the laminated films will peel off after long-term storage. Next, experiments will be carried out to clarify the effects of the present invention. The method for evaluating surface properties adopted in the experimental examples is as follows. (A) Haze Measured according to JIS-K-6714. (B) Lamination strength After printing with cellophane ink, coat with polyethyleneimine, dry, and then laminate with low density polypropylene at 290°C to a thickness of 30 μm using a melt extrusion method. Immediately after storage or treatment under various conditions, the film and polypropylene layer are peeled off and the adhesive strength is measured.
The peeling conditions are 180 degree peeling and a speed of 200 mm/min. However, products treated with boiling water and retort were laminated using an isocyanate adhesive, and after lamination, they were aged at 40°C for 2 days before evaluation. Film manufacturing example Polyethylene terephthalate resin [intrinsic viscosity
0.65 dl/g] was melt-extruded at 280°C, and the unstretched film was then heated 3.2 times in the machine direction at 90°C and 95°C.
The film was stretched 3.5 times in the transverse direction and further heat-set at 230°C for 3 seconds to obtain a biaxially stretched film with a thickness of 12 μm. The films obtained above were processed using the apparatus shown in FIG.
It was subjected to corona discharge treatment under the conditions shown in (1) and (2). In Examples (1) to (3) of the present invention, a gas mixture of nitrogen gas and air is supplied from the gas supply pipe 4, and the gas outlet 5
This is a case where the gas is blown from the film surface in a substantially perpendicular direction, that is, along the direction of discharge generation. In addition, in comparative example (1), the electrode cover 2
Nitrogen gas is supplied only inside the chamber, and the discharge atmosphere is the same as that of the example.
Same as (1) (O ₂ = 0.1%), but gas outlet 5
Comparative Example (2) is a case in which the corona discharge section was placed under an atmospheric atmosphere. ESCA values are also listed in Table 1. When the haze and lamination strength of the corona discharge treated film were determined, the results shown in Table 2 were obtained.

【table】

【table】

【table】

[Table] As is clear from Tables 1 and 2, in Comparative Examples (1) and (2), [Δoxygen index/Δnitrogen index] was high, and atmospheric removal from the film surface was insufficient. On the other hand, in Examples (1) to (3), [Δoxygen index/Δnitrogen index] was within the range of 1.5 to −3.5, indicating that they had excellent adhesive properties. That is, by adopting the configuration of the present invention, it is possible to remove the entrained air layer on the film surface, and it is confirmed that the removal of the entrained air cannot be achieved by simply changing the discharge atmosphere to a nitrogen atmosphere. Ta. Next, the film of Inventive Example (2) was washed with isopropyl alcohol, and the film after washing was evaluated (Table 3).

【table】

【table】 [Brief explanation of drawings]

Figure 1 is a conceptual diagram showing the implementation status of the present invention, Figure 2
The figure is a sketch diagram illustrating the discharge-side electrode used in the present invention, FIG. 3 is an explanatory diagram showing the state of destruction of the accompanying air layer, and FIGS. 4 and 5 are explanatory diagrams showing an example of the electrode cover. 1...metal drum, 2...electrode cover, 3...
Discharge side electrode, 5... gas jet port, 6... film.

Claims (1)

[Scope of Claims] 1. A corona discharge comprising a polyester molded product composed of dibasic acid residues and glycol residues, of which 80 mol% or more is terephthalic acid, with at least one pair of electrodes facing each other. When continuously transferring to the processing equipment to perform corona discharge treatment, nitrogen gas or a nitrogen-containing composite composition gas mainly composed of nitrogen gas and with an oxygen content of 20% by volume or less is applied to the corona discharge treatment surface of the molded product. When spraying, the gas is continuously sprayed along the discharge generation direction from the side of the discharge-side electrode facing the molded product, so that the gas accompanies the transfer surface of the molded product. The accompanying air layer carried into the corona discharge treatment equipment is destroyed and dispersed and replaced with the blown gas, and the oxygen index and nitrogen index in the thin layer portion within 100 Å from the outermost surface of the molded article are reduced by the corona discharge treatment. When the amount of change from before to after corona discharge treatment is defined as Δ oxygen index and Δ nitrogen index, the ratio between the two [Δ oxygen index / Δ nitrogen index] is set to 1.5 to −3.5, and the corona in the thin layer portion A method for producing a highly adhesive polyester molded article, characterized in that the nitrogen index after discharge treatment is 3 or more. (Here, the oxygen index and nitrogen index are determined by the following method: ESCA spectrometer
Using ES-200 model (manufactured by Kokusai Denki Co., Ltd.), the integrated intensity was determined from the 1s orbital spectrum of carbon on the surface of the molded product, and the integral determined from the peak corresponding to the binding energy of organic nitrogen from the 1s orbital spectrum of oxygen. The ratio with the strength is calculated, and the number of oxygen per 100 carbon atoms is determined based on the integral ratio, and this value is defined as the oxygen index. Regarding the nitrogen index, the number of nitrogen per 100 carbon atoms is determined by the same method, and this is defined as the nitrogen index. )