JPS59191737A - Production of highly adhesive polyester molding - Google Patents

Abstract

PURPOSE:To provide the titled molding having excellent adhesion to various substrates, by carrying out a corona discharge treatment by spraying a gas having a specified oxygen content on a surface to be treated. CONSTITUTION:In the corona discharge treatment of a molding of a polyester composed of a dibasic acid residue composed of at least 80mol% of terephthalic acid and a glycol residue comprising continuously feeding it to a corona discharge treatment device, a gas contg. 20vol% or less oxygen or a gas mixture thereof is sprayed on the surface of the molding to be subjected to the corona discharge treatment to such an extent that the ratio (DELTA oxygen index/DELTA nitrogen index) of the rates of the changes of oxygen index and nitrogen index in the thin layer within 100Angstrom from the surface of the molding before and after the corona discharge treatment is 1.5-3.5, and the nitrogen index in the thin layer within 100Angstrom from the outermost surface of the molding after the corona discharge treatment is 3 or above, thus producing the titled highly adhesive polyester molding.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a polyester molded article with good adhesiveness, and more specifically, by controlling the change in the atomic composition of the surface layer of the molded article by corona discharge treatment. It concerns how to obtain it.

Surface modification of plastic molded products by corona discharge is
It is known as a processing technique for film, and has achieved substantial effects such as "improving adhesiveness" by activating the surface. However, the results are not completely satisfactory.

The wood inventors have focused on polyester molded products, for example, applying corona discharge treatment to polyester films to improve their surface properties (particularly to improve adhesion)11. I thought of establishing a method that would allow (9).

For example, as a corona discharge treatment method for plastic molded products,
As seen in Japanese Patent Publication No. 4B-17747, there is a technique for promoting chemical changes on the discharge surface by supplying an organic solvent to the discharge section, but it is difficult to apply this to molded products where residual solvent is a problem.

Also Journal of Applied Polym
er 5science.

Vol, 15. P, 13B5-1375 (+971) describes a technique of performing corona discharge treatment in an inert gas atmosphere, and suggests that the influence of activation or deterioration due to the treatment atmosphere may be caused by changing the atmospheric atmosphere to, for example, a low-oxygen atmosphere. Techniques have also been proposed to perform processing in place of . However, this type of conventional method requires a large amount of inert gas, resulting in high costs.Furthermore, corona discharge technology for running film under an inert atmosphere eliminates atmospheric air entrained by the film. A special shield made of cotton is required to cut it off, making the equipment complex.
Even so, a complete or almost complete inert atmosphere was not guaranteed, and only a substantially low oxygen atmosphere was formed, so a low treatment level had to be maintained.

The reason why conventional improvement processing methods cannot achieve sufficient results can be considered as follows. In other words, the key to improving processing efficiency is thought to be the gas atmosphere in the discharge processing section, but conventional improvement methods only address the gas atmosphere within the processing system or chamber; This seems to be because shielding failure due to accompanying flow (outside air) in the surface layer is not taken into consideration. Therefore, patch type static 1
Processing in the 1-state would alleviate the above-mentioned problems, but this would significantly reduce industrial productivity and raise market prices, making it practical only for limited applications. . Moreover, if we try to increase the processing effect through continuous processing as described above, the processing speed will inevitably slow down, but this will damage the surface of the processed object and cause problems such as poor appearance, poor adhesion, and increased blocking. is derived. In conventional corona discharge treatment under atmospheric conditions, the surface of the object to be treated is oxidized and oxidized deterioration products are generated on the surface. ” - cannot be made to do so.

The wood inventors have been fascinated by this situation for some time, and at first they conducted research aimed at improving the corona discharge treatment technology itself, as usual. As a result, when a single composition or composite composition gas with an oxygen content of 20% by volume or less is sprayed onto the treated surface, the amount of oxygen gas on the surface of the molded product is extremely small, and the treatment effect is mainly affected by the direct influence of nitrogen gas. After learning that this could be obtained, the present invention was completed. Oxygen content 2
The reason why the corona discharge surface becomes strongly influenced mainly by nitrogen gas when a single composition gas or a composite composition gas of 0% by volume or less is sprayed has not been fully elucidated, but the following is tentatively explained. It can be predicted 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% by volume. 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 blowing means according to the present invention is adopted, the entrained air composition is Since part or all of the air layer is expelled and replaced, the composition of the accompanying air layer changes. This change is due to air containing 21% oxygen by volume being replaced by blowing gas containing less than 20% oxygen by volume, 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 discussion above, there is a point in blowing gases that contain less than 20% oxygen, so gaseous components other than oxygen include nitrogen gas, Regardless of argon gas, helium gas, )2 m gas, etc.
Alternatively, they may be used alone, and in either case,
The effect of nitrogen gas will become significant.

Based on the improved results of the corona discharge treatment technology as described above, we attempted to apply it to polyester molded products.
The adhesion was significantly improved and the height was 11. It was confirmed that the adhesiveness did not decrease even under λ and high humidity, and the present invention was completed.

That is, the gist of the present invention lies in the following points.

80 mol% or more of polyester molded product consisting of two groups of X-acid residues consisting of terephthalic acid and glycol residues is continuously fed to a corona discharge treatment device comprising at least one pair of electrodes facing each other. When carrying out corona discharge treatment by transferring the molded article to the surface of the molded article, a gas of a single composition or a composite composition having an oxygen content of 20% or less is blown onto the corona discharge treated surface of the molded article. The ratio between each change in oxygen index and nitrogen index before and after corona discharge treatment in the thin layer within [Δ oxygen index / Δ nitrogen index] is 1.5 to -3.5, and the outermost surface of the surface of the treated object The nitrogen index after corona discharge treatment in the thin layer part within 100A from
A method for producing a highly adhesive polyester molded article, characterized in that:

(The oxygen index and nitrogen index were determined by the following method. Using an ESCA spectrometer ES-200 model (manufactured by Kokusai Electric Co., Ltd.), the integral was determined from the 1s orbital spectrum of carbon on the surface of the molded product. Calculate the ratio between the intensity and the integrated intensity obtained from the peak corresponding to the binding energy of organic nitrogen from the ls orbital spectrum of oxygen, and calculate the number of oxygen per 100 carbon atoms based on the integral ratio. , this value is defined as the oxygen index. Also, 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 that is the object of the present invention is a dibasic It is a polyester composed of acid residues (80 mol% or more of the dibasic acid is terephthalic acid) and glycol residues. 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, cepatic acid, succinic acid, oxalic acid, etc. groups, and also residues of oxyacids such as p-hydroxybenzoic acid can be used. In addition, the glycol residue is a normal alkylene glycol residue, and examples thereof include residues such as ethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, and cyclohexane dimetatool. However, particularly practically, residues of ethylene glycol, tetramethylene glycol, and cyclohexane dimetatool are used. A particularly useful polymer is polyethylene terephthalate or polytetramethylene terephthalate.

The most typical example of the molded product of the present invention is a film or sheet (hereinafter referred to as a film), and it is applicable to unstretched films, uniaxially stretched films, biaxially stretched films, etc., but other Examples of molded articles include long articles such as fibers, pipes, tapes, woven fabrics, and nonwoven fabrics.

When forming the molded article using the polyester,
Although it may be produced from polyester alone, other polymer components may be blended within the range that does not adversely affect the properties of the polyester molded product, and generally it is not more than 20% by weight based on the total weight of the composition. Mix within the range. 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, antifogging agents, ultraviolet absorbers, flame retardants, clarifying agents, antioxidants, light stabilizers, and antistatic agents are added based on the type and purpose of the molded product. , may contain additives such as dyes and pigments.
All materials that do not adversely affect the performance of corona discharge are included in the scope of the present invention, regardless of whether they are used singly or in combination.

In producing a polyester molded article using a polyester composition made of the above-mentioned materials, a known method may be followed for each molded article, and the scope of the present invention may be determined depending on the specificity of the manufacturing method. There is no deviation from this. Therefore, the method for producing the molded product may be freely selected, but since the typical molded product 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 a film from the raw material of the composition in I- by a normal polyester film forming method, such as the T-Guy method or the inflation method. If this is stretched in one or two directions, 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
Sometimes a method is adopted in which corona discharge is applied while replacing the product once it has been rolled up.

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. A gas with a single composition or a composite composition with an oxygen content of 20% by volume or less [specifically, a gas from which an appropriate amount of oxygen has been removed from air, a gas from which an appropriate amount of something other than oxygen has been added to air, and N2 or H2, Ar, CO2, Xe, Kr, CI2, NH3,
A mixture of inert gas such as NOX or ionic gas (hereinafter abbreviated as inert gas for convenience) can be blown. The blowing speed is not particularly limited, but is preferably 1% or more of the transfer speed of the polyester molded material.As will be detailed later, the speed is 100% from the outermost surface of the surface to be treated.
By strictly specifying the relationship between the oxygen index and nitrogen index before and after corona discharge treatment in the thin layer part within A, various materials (e.g. metals; various inks, especially cellulone inks, water-based inks, etc.); resins, For example, it is possible to obtain a polyester molded product having extremely excellent adhesion to vinylidene chloride (single or copolymers, functional group-containing resins, etc.).

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, the shape of the cover, etc. shown in the drawings are only representative. Since the drawings merely show an example of application to a 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 a main part showing the implementation concept of the present invention, and 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 discharge side electrode. The side electrodes, 4 are gas supply pipes, 5 are gas jets 1-1.6 are running films. That is, the film 6 is attached to the metal drum 1 rotating in the direction of arrow A.
The discharge side electrode 3 is introduced from the direction of arrow B and further pulled out in the direction of arrow C, and is connected to a high voltage generator (not shown), and the discharge side electrode 3 is connected to a high voltage generator (not shown), and polyester, epoxy resin, ceramic, chlorosulfonated polyethylene, Under the influence of high-pressure corona generated by applying a high voltage of several thousand to several hundred V at a high frequency of several hundred KC/S between the metal drum 1 covered with EP rubber, silicone rubber, etc., If it is in the atmosphere, ozone and nitrogen oxides are generated and carbonyl groups and carboxyl groups are formed on the surface of the film, 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 the tree example, the entire corona discharge atmosphere is isolated from the atmosphere by the electrode cover 2, and a gas outlet 5 is provided on the discharge side electrode 3 to blow inert gas toward the surface of the film 6. Since the nitrogen gas is configured in a similar manner, the oxygen content in the entrained air layer is substantially reduced, thereby eliminating the above-mentioned problem, and the influence of nitrogen gas is greatly increased, thereby reducing corona discharge to the surface layer of the film 6. The effect can be maximized.

This situation will be explained in more detail as follows.

In other words, a slight entrained air layer is formed on the surface of the film 6 that enters at a fairly high speed along the direction of arrow B, and even if the atmosphere in the corona discharge section is replaced with an inert gas, the film The surface of 6 is still in an atmospheric atmosphere. Therefore, in carrying out the present invention,
As shown in FIG. 3, by strongly blowing inert scum onto the film surface and bursting and dispersing the entrained air layer 7 with the jet stream 8, the gas composition in the entrained air layer 7 on the film surface is changed and nitrogen gas is Increase the ratio. In some cases, the surface is almost completely replaced with an inert gas. The flow velocity of the jet stream 8 necessary to obtain the effect described above by bursting and dispersing the accompanying air layer 7 cannot be determined uniformly because it varies depending on the shape and size of the object to be treated, the speed at which it is carried into the processing equipment, etc. As a result of experiments, it was found that it is most preferable to determine the speed based on the speed of entry of the entrained air layer 7 (in other words, the speed of transport of the material to be treated). That is, the inert gas jet velocity is set to 1% or more, preferably 10% or more, of the conveyance speed of the material to be treated.
More preferably, by increasing the amount to 40% or more, the entrained air layer 7 can be destroyed and dispersed to such an extent that the disadvantages described above are not substantially eliminated. The angle at which the ejected gas blows onto the film can be freely selected depending on the effective angle. The speed at which the material to be processed is carried in is generally about 1 to 500 m/min.

By adopting such conditions, the accompanying air layer can be destroyed and dispersed, and the vicinity of the 11 corona discharge parts can be protected with an inert gas atmosphere at the same time. The electrode cover 2 shown 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 implementing the present invention, the electrode cover 2 may be removed from time to time, but in order to suppress the amount of inert gas consumed, it is desirable to reconsider its function as an atmosphere-maintaining device. As shown in Fig. 4, if the lower end (film side) of the cup 2 is squeezed and at the same time inert gas is introduced into the cover 2 from the conduit 10, the gas will be converged along the inner surface of the slope 9. The gas flows in the direction of the arrow, and a gas curtain effect is exerted at the entrance 11 of the cover 2. That is, the intrusion of the accompanying air layer is blocked on the input side 1, and the value of the electrode cover 2 is further improved.

Furthermore, as shown in FIG. 5, if the extension cover 11 is placed close to the surface of the molded product, the extension cover 11 will be filled with inert gas leaking from inside the cover 52. Therefore, the accompanying air layer entering from the cover 11 is also destroyed and dispersed little by little as it progresses inside the cover 11. 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, it is also possible to blow inert gas from the extension cover 11, and in this case the blowing angle can be freely selected, but in any case, the inert gas can be blown directly at the film introduction part. Since active gas is blown, the replacement efficiency for the entrained air layer is extremely high.

On the other hand, on the exit side of the film 6 (the right side in Figure 4), the gas inside the cover 2 is discharged along with the traveling film 6, so what considerations should be taken on the entrance side regarding sealing performance or air intrusion barrier properties? Although not necessary, 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 at the inlet and outlet sides of the cover 2 to the minimum level, the film running speed should be at least 0.2%, preferably 10% or more. It is desirable to release the film onto the film surface at a speed of -. Regarding the jetting speed of inert gas, please refer to the gas jetting port 5 and the cover 2.
The entry and exit of
It is not really necessary to set a limit on the amount of water, and it may be determined appropriately based on the balance between economical efficiency and the required quality of the final product.

By setting the processing conditions as described below, the processing effect of corona discharge can be enhanced and the adhesion properties can be greatly improved. We proceeded with further research, believing that it was necessary to quantitatively understand the surface characteristics before and after. As a result, (1) the ratio of the amount of change in the oxygen index and nitrogen index after the corona discharge treatment part e in the thin layer within 1 OOA of the surface of the workpiece [Δoxygen index/Δnitrogen index], and (2) the same <By controlling the nitrogen index after corona discharge treatment in a thin layer within 100A of the film surface to By,
It has been found that a high degree of adhesion can be guaranteed. In other words, the facts found in (1) above are that [Δoxygen index/Δnitrogen index 1 is 1.5 to -3.5, and in (2) above, the nitrogen index after treatment is By strictly controlling the processing conditions and processing atmosphere of corona discharge, we can make it possible to reduce This means that the adhesiveness with various synthetic resins such as resins and functional group-containing resins can be dramatically improved, and will be described in more detail below.

First, a polyester molded article that satisfies the requirement of [nitrogen index ≧3] specified in the present invention can sometimes be obtained under conventional treatment conditions, and can also be realized by known corona discharge treatment in a nitrogen gas atmosphere. be. However, as explained earlier, it is difficult to put it into practical use on an industrial scale, as large-scale equipment is required to ensure such a high level of nitrogen index, at least with the conventional method, which is intended for continuous processing. 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 components into the material, the nitrogen index will increase, but if you consider the fact that just mixing antistatic agents and lubricants, which are N-containing components, will not improve the adhesion, but will actually decrease it, the nitrogen index will increase. It is clear that an increase in index does not directly correlate with adhesion. Therefore, we also investigated other factors that affect adhesion, and found that the value calculated by [Δ oxygen index / Δ nitrogen index] almost accurately represents the corona discharge treatment effect, that is, the adhesion propensity effect. It has been confirmed that those treated to give this value of 1.5 to -3.5 exhibit a high level of adhesion suitable for the purpose. Incidentally, even if the nitrogen index within 100A of the surface layer after treatment is 3 or more, if [Δoxygen index/Δnitrogen 9 index] exceeds 1.5, the corona discharge treatment effect is insufficient. High levels of adhesion cannot be achieved.

In this sense, the treatment method of the present invention is adopted, and the nitrogen index is 3 or more, and [Δoxygen index/Δnitrogen index] is 1.
It is essential to control the processing conditions so that the ratio is between 5 and -3.5. Incidentally, it was practically extremely difficult to make this ratio smaller than -3.5.

By the way, [Δ oxygen index / Δ nitrogen index 1] indicates that the oxygen atoms constituting the polyester, the oxygen atoms in other polymers that may be blended, or the inherent oxygen atoms in various additives are released and removed by the inert gas. , or may be replaced and removed by nitrogen atoms in the inert gas, resulting in a negative value as described above. This Yanas area is generally -140 to 0
In this range, favorable results can be obtained in that the change in adhesive strength over time becomes extremely small and the blocking resistance is improved.

The present invention is roughly constructed as described above, and in addition to specifying the discharge treatment conditions, the treatment effect can be constantly grasped from the amount of change in the oxygen index and nitrogen index of the surface layer before and after treatment. This makes it possible to reliably obtain polyester molded products with excellent adhesion to various materials.
is. 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 surface layer will be transferred to the back side during winding and storage, and there is no worry that the printing ink will peel off when it is actually applied as a film package. Furthermore, since the adhesive properties with other film base materials are also improved, there is no possibility that the laminated film 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.

(^) Haze Measured according to JIS-8714 (B) Lamination strength After printing with cellophane ink, coating with polyethyleneimine and drying at 290'C! of low-density polypropylene is laminated using a melt extrusion method to a thickness of 30 ILm. Immediately after storage or treatment under various conditions, the adhesive strength between the film and the polypropylene layer is measured by peeling the film and the polypropylene layer. The peeling conditions are 180 degree peeling,
The speed is 200 mm/min.

However, products treated with fresh water and retort were laminated using an incyanate adhesive, and after lamination, they were aged at 40°C for 2 days before evaluation.

Polyethylene terephthalate resin [intrinsic viscosity 0.65]
dl/g ] at 280°C, and the unstretched film was then heated to 90°C by 3.2 times in the machine direction 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 film obtained above was used as the invention example (+) in Table 1.
, We conducted corona discharge treatment under the conditions shown in (2). Furthermore, Comparative Example (1) in Table 1 is a case where the corona discharge part is simply protected in a nitrogen gas atmosphere, and Comparative Example (2) in Table 1 is a case where the corona discharge part is in an air atmosphere. . 1st
The ESCA values are also listed in the table.

When the haze and laminate strength of the corona discharge treated film were determined, the results shown in Table 2 were obtained.

3 Table 1 4 Table 2 (1) Table 2 (2) Table 2 (3) 7 As seen in Table 1.2, the corona discharge treated film of the present invention has a ratio of [Δoxygen index/Δnitrogen] index] was 1.5 or less (especially a negative value), and the laminate strength was significantly improved.

Next, the film of Inventive Example (2) was washed with isopropyl alcohol, and the film after washing was evaluated (Table 3).

8 Table 3

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram showing the implementation status of the present invention, Fig. 2 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 Fig. 4.5. The figure is an explanatory diagram showing an example of an electrode cover. 1... Metal drum 2... Electrode cover 3...
Discharge side electrode 5... Gas outlet 6... Film applicant Toyobo Co., Ltd. 1 205-

Claims (1)

[Claims] Corona discharge treatment in which a polyester molded product composed of dibasic acid residues and glycol residues, of which 80 mol% or more is terephthalic acid, is faced with at least one pair of electrodes. When continuously transferring to the apparatus and performing corona discharge treatment, a single composition gas or a composite composition gas having an oxygen content of 20% by volume or less is sprayed onto the corona discharge treatment surface of the molded article. The ratio of the amount of change in the oxygen index and nitrogen index before and after corona discharge treatment in a thin layer within 100 A [Δoxygen index/Δnitrogen index] is 1.5 to -3.
, 5. A method for producing a highly adhesive polyester molded article, which is characterized in that the thin layer portion within 100 A from the outermost surface of the object to be treated has a transformation index of 3 or more after corona discharge treatment. (However, the oxygen index and nitrogen index were determined by the following method. That is, using an ESCA spectrometer ES-200 model (manufactured by Kokusai Electric Co., Ltd.),
Calculate the ratio between the integrated intensity obtained from the orbital spectrum and the integrated intensity obtained from the peak corresponding to the binding energy of organic nitrogen from the IS orbital spectrum of oxygen, and based on the integral ratio, Find the number of oxygen atoms and define this value 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. )