JPS5936655B2 - Method for producing polyolefin composition - Google Patents

Description

[Detailed description of the invention] The present invention relates to new useful polyolefin compositions.

More specifically, the present invention relates to a polyolefin composition that has excellent adhesion to various substrates. Polyolefins such as polyethylene, polypropylene, and polybutene have various excellent properties as thermoplastic resins, and are well known as general-purpose resins that find use in a wide range of fields such as hollow products, fibers, films, and injection molded products. However, since polyolefin resins do not have functional groups in their molecules, they have excellent chemical resistance, but because they have polar groups, they have poor performance in terms of adhesion and printability, which greatly limits the scope of their use. . Various methods have hitherto been taken to improve this drawback. Modifying the polyolefin by adding an unsaturated compound, particularly an unsaturated carboxylic acid or its anhydride to the polyolefin and heating it is an effective means that has been conventionally used to improve the above-mentioned drawbacks of polyolefins. one of.

As a further advance of such improvement measures, JP-A-49-109432 describes a polyolefin composition comprising 99 to 20 parts by weight of the above-mentioned modified polyolefin and 1 to 80 parts by weight of an inorganic filler. It is also stated that the addition of an inorganic filler improves the properties (particularly the adhesive strength with other substances) more than in the case of the above-mentioned modified polyolefin alone.

Examples of the inorganic filler include powder, plate, or fibrous inorganic materials such as talc, silica, calcium carbonate, asbestos, clay, gypsum, anhydrous calcium sulfate, bentonite, glass, mica, iron oxide, and titanium white. There is. However, although the composition described in JP-A-49-109432 has excellent adhesive properties (adhesive strength to other materials), it has the drawback of being weak against bending and easily cracking.

As a result of intensive research to find a polyolefin composition that has excellent adhesive properties, is resistant to bending, and is resistant to cracking, the present inventor has found that 100 parts by weight of polyolefin is mixed with at least one selected from the group consisting of unsaturated carboxylic acids and their anhydrides. By adding and heating 0.01 to 20 parts by weight of the compound and 0.1 part by weight or more but less than 1 part by weight of silicon dioxide,
The inventors have discovered that a composition excellent in both adhesion and bending resistance can be obtained, and have arrived at the present invention.

A feature of the present invention is that a very small amount (0.1 part by weight or more and less than 1 part by weight, based on 100 parts by weight of the polyolefin) of silicon dioxide is used together with the polyolefin and the unsaturated carboxylic acid or its anhydride.

When using less than 0.1 part by weight of silicon dioxide per 100 parts by weight of polyolefin, a composition with excellent adhesive properties cannot be obtained. On the other hand, when 1 part by weight or more of silicon dioxide is used per 100 parts by weight of polyolefin, only a composition with low bending resistance and easily cracked can be obtained. In the present invention, polyolefins include homopolymers of olefins such as ethylene, propylene, butene, hexene, and 4-methylbenzene, copolymers of these olefins, vinyl compounds such as styrene and butadiene, diene compounds, etc. It means copolymers with olefins and mixtures of these polymers (including copolymers).

Examples of unsaturated aliphatic carboxylic acids and their anhydrides used for modifying polyolefins include maleic acid, fumaric acid, crotonic acid, acrylic acid, methacrylic acid, maleic anhydride, and itaconic anhydride.

The polyolefin composition of the present invention comprising the polyolefin, the carboxylic acids, and silicon dioxide is distinguished from a mere mixture.

In other words, even after extracting this composition with hot acetone, which is a good solvent for the carboxylic acids, when taking an infrared spectrum of the composition, an absorption band peculiar to the carboxylic acids is observed, indicating that these carboxylic acids are a polyolefin. It is presumed that there is some kind of chemical bond with. The carboxylic acids (or anhydrides thereof) and silicon dioxide can be incorporated into the polyolefin No. 5 by various methods.

That is, a method in which the carboxylic acids and silicon dioxide are simultaneously added to polyolefin and heated to react, a method in which silicon dioxide is added after adding the carboxylic acid to polyolefin and heated to react, and a method in which silicon dioxide is added to polyolefin and then silicon dioxide is added to polyolefin. A method of adding the above carboxylic acids and heating, a method of adding a mixture of silicon dioxide and the above carboxylic acids to polyolefin and causing a heating reaction, 4. method, a method of combining these methods, and a method of adding one or two components in predetermined amounts. A so-called masterbatch method in which an excess amount is added in advance can also be used. Furthermore, in the reaction of the carboxylic acids, a so-called radical generator such as oxygen, dixyl oxide, ditertiary butyl peroxide, or tertiary butyl perbenzoate may be present. In the present invention, the heating reaction may be carried out by using an extruder, or by using a kneading machine such as a Banbury mixer or a ribbon mixer roll.

Although this reaction can be carried out without a solvent or in the presence of a solvent, it is preferable to carry out the reaction without a solvent from the viewpoint of post-treatment steps. The time required for this reaction varies depending on the reaction conditions, so it cannot be definitively stated, but a few seconds to several hours is generally sufficient, and a very short period of several minutes is sufficient.The reaction temperature also depends on the temperature at which radicals are generated. Particularly when the reaction is modified without a solvent, the reaction treatment is preferably carried out at a temperature higher than the melting point of the polyolefin used. The amount of the carboxylic acid (or anhydride thereof) used in the present invention is 0.01 to 20 parts by weight, preferably 0.05 to 10 parts by weight, based on 100 parts by weight of the polyolefin. If the amount added is too small, the desired adhesive strength cannot be obtained, and if the amount added is too large, side reactions such as excessive crosslinking and decomposition reactions become significant, making it impossible to obtain the desired results. Silicon dioxide refers to so-called silica, which is commonly used as a natural product or a synthetic product, and it does not matter whether the silica has pores or not.

For example, preferable examples include fine powder silica and silica gel having a particle size of 0.1 μm or less. A particle size of 100μ or more is suitable.

The amount of silicon dioxide used should be 0.1 part by weight or more and less than 1 part by weight per 100 parts by weight of polyolefin.

If the amount of silicon dioxide used is less than 0.1 parts by weight per 100 parts by weight of polyolefin, its contribution to adhesive strength is small and becomes meaningless. Furthermore, even if the amount of silicon dioxide used is 1 part by weight or more per 100 parts by weight of polyolefin, no decrease in heat-sealing strength to metal is observed, but the base polyolefin becomes extremely brittle, making composite plates heat-sealed to aluminum plates etc. If you try to bend it to more than 900 degrees, it will break and drawing will be difficult, which is not desirable. The composition of the present invention has adhesive properties not only to metals such as aluminum, titanium, nickel, iron, steel, stainless steel, copper, zinc, and tin, but also to basic synthetic resins such as wood, cloth, paper, and polyamide. It also shows good adhesion.

Furthermore, since the composition of the present invention retains the basic properties of the original polyolefin, it is compatible with the unmodified polyolefin. Therefore, the composition of the present invention can be used not only for adhesion between metals and coating metals, but also as an adhesive for bonding metals and basic synthetic resins to synthetic resins that cannot be directly bonded. Furthermore, additives such as colorants, stabilizers, blowing agents, fillers, etc. can be mixed into the composition of the present invention, depending on the intended use, without impairing the original performance. Examples 1 to 4 3 parts by weight of maleic anhydride and 2,5-dimethyl 2,5-di(
30.1 parts by weight of (tertiary butylperoxy)hexyne was added and mixed, and the mixture was extruded using an extruder set at 200°C.

The amount of hot acetone extracted from this reaction mixture was 0.2%, and there was no change in the infrared vector before and after extraction, and no change in the intensity of the 5.6μ absorption band, which is a characteristic absorption of maleic anhydride, was observed. The fact that maleic anhydride is not extracted at all by hot acetone, which is a good solvent, and that the infrared spectrum, especially the absorption intensity at 5 and 6μ, does not change at all before extraction with acetone suggests that there is some kind of interaction between maleic anhydride and opolyethylene. Bonding is expected. A predetermined amount (see Table 1) of finely powdered silica was added to 100 parts by weight of the maleic anhydride-modified polyethylene thus obtained, and the mixture was heated at a predetermined temperature for 5 minutes using a corrosion-resistant aluminum plate with a thickness of 0.1 mm (in Example 4) It was heat-sealed to a thickness of 1 mm on an iron plate. 180 of these samples
Table 1 shows the results of the 0 peel test (JISK-6854) and the 1800 bend test. Further, the adhesive strength of the adherend obtained in this example was measured after immersing it in hot water at 70° C. for 10 days, and the adhesive strength did not decrease at all.

Reference Example 1 The same operation as in Example 1 was performed except that fine powder silica was not added to the maleic anhydride-modified polyethylene obtained in Example 1, and the results shown in Table 1 were obtained.

When this product was immersed in hot water at 70°C, the adhesive strength decreased to less than 0.5 kg/deposition within 24 hours. Reference example 2
~4 The same operation as in Example 1 was carried out except that finely divided silica was added in an amount outside the range of the present invention (see Table 1) to the maleic anhydride-modified polyethylene obtained in Example 1, and the results in Table 1 were obtained in all cases. As shown in Figure 1, cracks occurred during the bending test.

When the same operation as in Example 2 was performed except for changing to polyethylene, the 180° peel strength was 5.5 kg/25
It was abusive and hot.

Reference Example 5 The maleic anhydride-modified polyethylene used in Example 1 was heat-pressed to corrosion-resistant aluminum in the same manner as in Example 1, except that sodium oxide was used instead of finely powdered silica.

The 1800 peel strength was 3.5 kg/25n.

When this product was immersed in hot water at 70°C for 24 hours, the peel strength decreased to less than 0.5 kg/25 m. Example 6 100 parts by weight of medium density polyethylene having a specific gravity of 0.94 was charged into a small kneader and masticated at 170° C. for 5 minutes, after which 4 parts by weight of acrylic acid was added and kneaded well for an additional 5 minutes.

Next, 0.6 parts by weight of 2.5-dimethyl-2.5-di(tert-butylperoxy)hexine-3 was added and kneaded for 10 minutes to complete the reaction. The infrared absorption spectrum of this product after extraction with hot acetone showed strong absorption at 5.8μ, suggesting a bond between polyethylene and acrylic acid. 0.9 parts by weight of silica was mixed with 100 parts by weight of the acrylic acid-modified polyethylene thus obtained.
It was hot-pressed to a corrosion-resistant aluminum plate at 00°C for 5 minutes. The adhesive strength was 60k9/25mm. Comparative Example 6 The same operation as in Example 6 was performed except that silica was not added to the acrylic acid-modified polyethylene obtained in Example 6, and the 180° peel strength was 2.8K9/2.
It was 5mm.

Claims (1)

[Claims] 1. Adding 0.01 to 20 parts by weight of one or more compounds selected from the group consisting of unsaturated carboxylic acids and their anhydrides and 0.1 part by weight or more but less than 1 part by weight of silicon dioxide to 100 parts by weight of polyolefin. A method for producing a polyolefin composition with improved adhesiveness, the method comprising heating.