JPS59136333A - Manufacture of polyolefin molded article having high bonding property - Google Patents

Abstract

PURPOSE:To improve the corona treating effect, and to improve the bonding strength of a polyolefin molded article with various other materials, by passing the molded article continuously through a corona discharge treatment apparatus having oppositely placed electrodes, and specifying the ratios of O/C and N/C of the treating surface before and after the treatment. CONSTITUTION:A polyolefin molded article (e.g. film, etc. of polypropylene, etc.) is passed continuously through a corona discharge treatment apparatus having at least a pair of oppositely placed electrodes to effect the corona treatment of the surface. In the above process, the surface to be treated is blasted with a simple gas or a mixed gas (e.g. an inert gas such as N2, H2, etc.) having a composition other than the composition of air, to adjust the ratio of the differences of (O/C) and (N/C) in the thin layer within 100Angstrom from the surface before and after the treatment [DELTA(O/C)/DELTA(N/C)] at -3.5-0, and the (N/C) ratio in the thin layer within 100Angstrom from the surface after the treatment at >=3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a highly adhesive polyolefin molded product, and more specifically, to a polyolefin molded product that has sufficiently enhanced corona discharge treatment effects at a practical production level and has improved adhesion to various materials. The present invention relates to a method for manufacturing.

Corona discharge treatment of plastic films and molded materials has been carried out for a long time, and is an indispensable technique for surface modification of polyolefin films such as polyethylene and polypyrene, and its scope of application is increasingly expanding. It is expected that this will continue. In order to deal with this situation, it is necessary to improve the processing efficiency of corona discharge itself and explore its possibilities, and although extensive improvement research has been conducted so far, it is still not sufficient. I'm in a situation where I can't say anything.

For example, as a corona discharge treatment method for plastic molded products,
As seen in Japanese Patent Publication No. 48-17747, 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 Poly
mer Sc:tence.

you, 15,? , 1365-1375 (1971
) describes a technique of performing corona discharge treatment in an inert gas atmosphere, and if the effect of activation or deterioration due to the treatment atmosphere is suggested, the treatment may be performed by replacing the atmospheric ambient air with, for example, a low-acid cumulative atmosphere. Techniques for doing this have also begun to be proposed. However, this type of conventional method, such as Tokkosho! 56-
The method of No. 18381 required a large amount of inert gas, which caused the problem of high cost.
The method of No. 23634 (corona discharge technology under an inert ambient atmosphere for running film) requires a special shield structure to block the atmosphere that is entrained by the film, making the equipment complex, and still A completely or almost completely inert atmosphere was not guaranteed and one had to settle for a low treatment level.

The reason why conventional improvement processing methods cannot achieve sufficient results can be considered as follows. In other words, the key to increasing processing efficiency is thought to be the gas atmosphere in the discharge processing section, but conventional improvement methods only consider the gas atmosphere in the processing system or chamber as a problem, and do not focus on the surface layer of the object to be processed. This seems to be because the obstruction caused by the accompanying flow (outside air) is not taken into account. Therefore, if the processing was carried out in a stationary state using a batch method, the above-mentioned problems would be alleviated, but this would significantly reduce industrial productivity and raise market prices, so it is only practical for limited applications. cannot be converted into Moreover, in order to obtain a high processing effect through continuous processing as described above, the processing speed must be reduced, but this will damage the surface of the processed object and cause problems such as poor appearance, poor adhesion, and increased blocking. It's derived. In the conventional corona discharge treatment under atmospheric conditions,
Since the surface of the object to be treated undergoes oxidation and oxidized deterioration products are generated on the surface, adhesion cannot be improved beyond a certain level even if the degree of treatment is increased.

The present inventors have focused on these circumstances and have been conducting research with the aim of developing a corona discharge treatment method that can provide polyolefin molded products with a high degree of adhesion at an industrial production level. The present invention was made as a result of such research, and has a structure in which a polyolefin molded product is continuously passed through a corona discharge treatment device comprising at least one pair of electrodes facing each other to perform corona discharge treatment. In this process, the method of the present invention is applied by spraying a single gas or a mixture of gases having a composition other than air onto the surface to be treated, and after corona discharge treatment in a thin layer of 100 or less within 100λ of the surface to be treated. Polyolefin molded products include films, sheets, fibers, pipes, tapes, woven fabrics, non-woven fabrics, and other elongated products, and the polyolefins that make up these molded products include various known polyolefins. Typical polyolefins for films or sheets include:
Homopolymers such as polyethylene, polypropylene, polybutene-1, poly-4-methylpentene-1, polyhexene, various copolymers containing about 70 weight units or more of propylene constituent units, 40 weight-1 tq6 propylene constituent units
Examples include polyolefin blends containing a certain amount or more. In addition, stabilizers, lubricants, anti-blocking agents, antifogging agents, ultraviolet absorbers, flame retardants, clarifying agents, antioxidants, and light-fastening agents are added to molded products made of these polyolefins as necessary. , antistatic agents, dyes, pigments, and other additives may be included, 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 singly or in combination. .

In the present invention, the above-mentioned polyolefin molded product is treated,
Surface treatment is carried out by continuously passing the molded article through a corona discharge treatment device comprising at least one pair of electrodes facing each other. For example, air with an appropriate amount removed from it, or air with an appropriate amount added to it, as well as N, , Hl, Ar% co
, , o, , O8, Xθ, Kr, etc., including inert gases and ionic gases alone or in combination (but excluding air), hereinafter abbreviated as inert gas for convenience.] is sprayed.

The spraying speed is not particularly limited, but is preferably 1% or more of the feeding speed of the polyolefin molded product. As will be detailed later, before and after the corona discharge treatment in a thin layer of 100 or less on the surface to be treated, various materials (for example, gold M + various inks, especially cellulose-based inks, water-based inks, etc.; resins, such as vinylidene chloride-based Polyolefin molded articles with extremely excellent adhesion to resins (alone or copolymers, functional group-containing resins, etc.) 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, the shape of the cover, etc. shown in the drawings are only representative examples.
Further, 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. A side electrode, 4 a gas supply pipe, 5 a gas outlet, and 6 a running film. That is, the film 6 is introduced from the direction of arrow B into the metal drum 1 rotating in the direction of arrow A, and is further pulled out in the direction of arrow C. 3 and a metal drum 1 covered with polyester, epoxy resin, ceramic, chlorosulfonated polyethylene, EP rubber, etc. by applying a high voltage of several thousand to several hundred ■ at a high frequency of several hundred KC/S. Under the influence of the generated high-pressure corona, for example, in the natural atmosphere, ozone and nitrogen oxide are generated, and carbonyl groups and carboxyl groups are generated 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, thereby blocking the surface. 1 - In the example shown in this figure, 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 direct inert gas toward the surface of the film 6. Since the above-mentioned problem is solved and the film 6
The corona discharge effect on the surface layer can be maximized.

To explain this situation in more detail, a slight accompanying air layer is formed on the surface of the film 6, which heals in the direction of arrow B and enters at a fairly high speed, making the atmosphere in the corona discharge area inert. Even if the gas is replaced, the surface of the film 6 itself remains surrounded by the atmosphere. Therefore, in carrying out the present invention, as shown in FIG. Almost completely replaced with gas. The flow velocity of the jet stream 8 required to destroy and disperse the entrained air layer 7 cannot be uniformly determined because it varies depending on the shape and size of the object to be treated, the speed of conveyance to the processing equipment, etc., but as a result of experiments, It has been found that it is most preferable to set the value based on the entry speed of No. 7 (in other words, the transport speed of the object to be processed). That is, by setting the inert gas jet velocity to 1% or more of the conveyance speed of the material to be treated, preferably 10q6 or more, and more preferably 40q6 or more, the entrained air layer 7 can be eliminated to the extent that it is practically inconvenient. be able to. The speed at which the plate to be processed is carried in is generally about 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 is expected not only to function as an atmosphere retainer, but also to protect the electrode 3 from mechanical impact and to suppress accompanying flow even to the slightest extent. 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, by squeezing the lower end (film side) of the cover 2 and at the same time introducing inert gas into the cover 2 from the conduit 10, the gas flows in the direction of the arrow so that it is converged along the inner surface of the slope 9. The 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 value of the electrode cover 2 is further improved.

However, 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 running film 6, so what considerations should be taken on the entrance side regarding sealing performance or air infiltration barrier properties. Although it is 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 exert the above-mentioned sealing function on the inlet and outlet sides of the cover 2 to the minimum extent, it is necessary to release the liquid onto the film surface at a speed of at least 0.2q6 or more, preferably 1096 or more relative to the film running speed. is desired. 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 necessary to improve economic efficiency and the required quality of the final product. It should be decided appropriately based on the balance.

By setting the treatment conditions as described above, the treatment effect of corona discharge is enhanced and the adhesion is significantly improved.
In order to consistently and stably exhibit these effects, we conducted further research based on the belief that it was necessary to quantitatively understand the surface characteristics of the treated object before and after treatment. the result,
(2) It has been found that the adhesiveness of a thin layer within 100A of the surface of the object to be treated can be guaranteed at a corona discharge treatment level. In other words, by controlling the El- after treatment (and strictly controlling the surrounding atmosphere), for example, metals, various printing inks (especially cellulose-based inks, water-based inks, etc.), chloride Adhesion to various synthetic resins such as vinylidene-based single or copolymer resins and functional group-containing resins can be dramatically improved. Although there are various methods for measuring surface properties as described above, the most suitable one is the ESCA method.

Polyolefin molded articles satisfying the above requirements can sometimes be obtained under conventional treatment conditions, and can also be realized by known corona discharge treatment under a nitrogen gas atmosphere.

However, as explained earlier, in order to secure such a high level of (-) ratio as mentioned above, large-scale equipment is required in the conventional method, which targets at least continuous processing, so it is difficult to put it into practical use on an industrial scale. Met. On the other hand, the method of the present invention can be used to improve the performance. On the other hand, there is also a report that the adhesion of plastic materials to various materials is simply determined by the production ratio of N (relative to C) determined by the ESCA method. However, such reports capture only one aspect that affects adhesion. By the way, considering the fact that simply mixing an antistatic agent or lubricant with a varying N component to the material does not improve adhesion, but rather reduces it, an increase in the (-) ratio does not immediately correlate with adhesion. That is clear. Therefore, we also examined other factors that affect adhesion, and found that the values almost accurately represent the effect of corona discharge treatment, that is, the effect of improving adhesion.
It has been confirmed that those treated in such a way that this value becomes 1.8 or less exhibit a high level of adhesion that meets the purpose. By the way, it is not possible to obtain a high level of adhesion even if it is insufficient. In this sense, the treatment method shown in the figure is adopted between nuclear power plants, and the treatment conditions are set so that the ratio (5) above is 3 or more and [ON Δ(d)/Δ(d)] is 1.8 or less. It is essential to control.

ON However, as I was further researching [Δ(5)/Δ(-5,)], I realized that the region where the above ratio is negative,
In other words, even if the constituent oxygen atoms in the film (oxygen atoms brought in from the corona discharge treatment atmosphere, various oxygen-containing additives, and oxygen atoms derived from oxygen-containing polymer compounds that are mixed as necessary) are However, if the nitrogen atoms in the released and removed cine active gas are replaced and removed, and as a result, the number of nitrogen atoms increases, the above-mentioned effect becomes even more pronounced, especially in the range of -3.5 to 0. , the blocking resistance is further improved, and the change in adhesive strength over time is extremely reduced. Similarly, the formation of such a negative region is not due to the degree of formation of nitrogen gas, but rather,
Rather, it was found that it largely depends on the ratio of oxygen atoms in the film and the form of oxygen atoms present as described above. Thus, in the present invention, ON has determined [Δ(d)/Δ(d)] to be -3.5 to 0, but in reality, it is extremely difficult to obtain an area even smaller than 3.5. there were.

The present invention is roughly configured as described above, and in addition to stipulating the corona discharge treatment conditions, the treatment effect can be constantly grasped from the amount of change in the (j) ratio and (υ) ratio of the surface layer when turned on before and after the treatment. As a result, it has become possible to reliably obtain polyolefin molded products with excellent adhesiveness to various materials.

Next, an experimental example will be shown.

The method for evaluating surface properties adopted in this experimental example is as follows.

(1) Measurement using haze + JTS-6714 (2)
Printing Ink Adhesion Using a commercially available printing ink for cellophane, red and white printing was performed using a gravure printing machine.

After printing, it was simultaneously dried in the usual manner, and a tape peeling test was conducted using a commercially available cellophane tape manufactured by Chiban Co., Ltd.

[Tape peel test evaluation criteria]

5I No peeling 4; Ink peeling area less than about 5 inches 3I Ink peeling area 5-10% 2I Ink peeling area 10-50 1; Ink peeling area 50% or more (3) Lamination strength Printing using cellophane ink After that, it is coated with polyethyleneimine, dried, and then laminated with low density polyethylene at 290° C. to a thickness of 30 μm using a melt extrusion method.

Then, after 24 hours of aging, the film and polyethylene layer were peeled off and the adhesive strength was measured. The peeling conditions were 180 degree peeling and a speed of 200+++ m/min. (4) Other Adhesive Properties The vapor deposition properties of aluminum and the adhesion to vinylidene chloride resin were examined in the same manner as in section (2).

(5) (N/C) ratio and (0/C) by ESCA method
Ratio: ESCA spectrometer ES-200 type (
(manufactured by Kokusai Denki Co., Ltd.), one of the carbon atoms on the film surface was
The ratio of the integrated intensity obtained from the 8-orbital spectrum and the integrated intensity obtained from the peak corresponding to the binding energy of organic nitrogen from the IS orbital spectrum of nitrogen is calculated, and based on the integral ratio, the The nitrogen number was determined, and this value was defined and expressed as the (N/C) ratio. The ratio of carbon to oxygen on the film surface was similarly expressed as the number of oxygen per 100 carbon atoms as the (0/C) ratio. The (N/C) ratio and (0/C'') ratio in the strength wood specification are all based on this definition.

Example Isotactic polypropylene, polyoxyethylene (n=20) stearate (0.4 weight ratio based on the total amount of resin) and stearic acid monoglyceride (
0.2 weight ratio) to obtain a raw material composition for film forming,
A biaxially stretched film having a thickness of 25 μm was produced by a conventional method. This is used as the film to be processed, and the oxygen content is o, ooos
Corona discharge treatment was performed while injecting a volumetric amount of nitrogen gas at a spraying speed of 5 m/sec. The power used was 4800 joules/m2, the processing speed was 20 m/min, and the oxygen concentration in the processing atmosphere was 0.008% by volume.

For comparison purposes, a similar corona discharge treatment was performed on a sample in which the treatment atmosphere was simply replaced with nitrogen gas, and the characteristics were compared. The experimental results for the invention examples and comparative examples are also listed in Table 1. Note that the (-) ratio and <-5) ratio in the same table are values within 100λ of the surface layer of the film.

Example A film was formed in the same manner as in Experimental Example 1 by mixing isotactic polypyrene with sorbitan oleate (0.4 li% based on the total amount of resin). Corona discharge treatment was carried out under the same conditions as in Experimental Example 1, except that the nitrogen gas spraying speed was 10 m/sec, and the obtained films were compared in the same manner, and the results shown in Table 4 were obtained.

As can be understood from Table 1, the adhesiveness of the examples of the present invention was stronger than ever before, and was extremely excellent even when an organic additive was used.

4. An additional relationship is the region where the oxygen atoms in the film additive are released and the oxygen atomic weight decreases, and the ratio given above is further shifted to the minus side, specifically, in the range of -8.5 to 0. By targeting the area where the adhesive will become, we aim to increase the adhesion several times as much. In other words, the present invention uses the main parts of the essential features of the original invention as its main parts (the main parts of the essential features), and achieves all the same objectives as the original invention, and is patentable. This invention falls under Article 81, Item 1 of the Act.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram showing the implementation status of the present invention, and FIG. 2 is a conceptual diagram showing the implementation status of the present invention. Side tit = Exemplary sketch, No. 8
The figure is an explanatory diagram showing the destruction situation of the accompanying nitrogen layer, and Figure 4 is t&
It is an explanatory view showing an example of a cover. l...Gold scrap drum 2...vIL pole cover cover 8・Release'#((ttl+electrode 5...Gas outlet 6...Film applicant Kiyobo Co., Ltd. Figure 1 Figure 4 Figure 2

Claims (1)

[Claims] (1) When carrying out corona discharge treatment by continuously passing a polyolefin molded article through a corona discharge treatment apparatus comprising at least one pair of electrodes facing each other, a single or mixed composition other than air is applied to the treatment surface. A method for producing a highly adhesive polyolefin molded product, characterized by the ratio of the amount of change before and after Rona discharge treatment (in a thin layer of less than 100 layers on the surface of the object to be treated).