JPH059341A - Photodegradable polyolefin resin composition - Google Patents

Abstract

PURPOSE:To obtain the title composition capable of rapidly degrading when exposed to solar light or ultraviolet ray by adding a phosphorus-containing metal complex to a polyolefin resin in a specific amount. CONSTITUTION:The objective composition obtained by blending 100 pts.wt. polyolefin resin (e.g. polyethylene) with 0.0001-5 pts.wt. (preferably 0.01-l pts.wt.) phosphorus-containing metal complex (e.g. compound expressed by formula II) expressed by formula I (R<1> is alkyl, aryl, etc.; R<2> is alkyl, alkoxy, etc.; X<1> and X<2> are 0 or S; M is Cr, Mn, etc.; n is numerical value corresponding to valency of M) and stabilizer, plasticizer, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyolefin resin composition which deteriorates and decomposes and collapses extremely rapidly when exposed to sunlight or ultraviolet rays.

[0002]

2. Description of the Related Art Plastic resins such as polyolefin resins such as polyethylene, polypropylene, polyvinyl chloride and polystyrene are easy to melt and
Since it is inexpensive, it is widely used in the fields of containers, films, sheets, pipes, packaging materials, etc., and the total amount used is increasing.

However, these plastic resins are extremely stable under natural conditions. In addition, the conventional resins have been focused on improving durability, and since additives such as heat stabilizers, light stabilizers, and light deterioration inhibitors have been added, the original shape remains for a long time even after disposal. Therefore, it takes an extremely long time to be decomposed and reduced into nature.
Therefore, it is a social problem to destroy the natural circulation system and pollute the environment.

In order to solve such a problem, the plastic is separated and collected from the waste and reused, or when it cannot be recovered, it is burned together with the waste and used as a heat source. Alternatively, when it is left in the environment as waste, it is preferable to decompose it as soon as possible and reduce it naturally.

As one of the methods described in particular, there is a method in which a compound having a photosensitizing action is added to a plastic material and decomposed by irradiation with sunlight or ultraviolet rays.
If you can increase the rate of plastic decomposition,
It is believed that the rate at which plastic left in the environment is naturally reduced will increase, which will lead to the solution of environmental pollution. However, the preparation of such a photodegradable plastic has the drawback that, for example, expensive additives must be used in relatively large amounts.

[0006]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned conventional problems, and an object thereof is to provide an inexpensive plastic composition having high photodegradability, particularly a polyolefin resin composition. .. Another object of the present invention is to provide the above photodegradable polyolefin resin composition containing a predetermined phosphorus-containing metal complex.

[0007]

The photodegradable polyolefin resin composition of the present invention is a phosphorus-containing metal complex represented by the following general formula (I) with respect to 100 parts by weight of a polyolefin resin.
It contains 0.0001 to 5 parts by weight, whereby the above-mentioned object is achieved.

[0008]

[Chemical 2]

Here, R ¹ is an alkyl group, an aryl group or an aralkyl group, and R ² is an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an aralkyl group,
Or an aralkyloxy group, X ¹ and X ² are each independently O or S, and M is Cr, Mn, F
e, Co, Cu, Zn, Zr, W, or Ce,
n is a numerical value that is the valence of M.

Of the phosphorus-containing metal complexes used in the present invention, commonly used compounds are shown in Table 1.

[0011]

[Table 1]

The above phosphorus-containing metal complex is an Organophosphor
usCompounds , 2nd edn, Kosolapoff, GMand Maier, L., V
It is synthesized by a known method described in ols 1-7, Wiley, New York, 1972-76 and the like. For example, the compound shown as No. 9 in Table 1 is obtained by reacting benzene and diphosphorus pentasulfide under an aluminum chloride catalyst to obtain Ph ₂ P (S) SH (provided that P 2
h represents a phenyl group. ) And reacting with FeCl ₃ or the like.

The above-mentioned phosphorus-containing metal complex is activated by the energy of light to act as a photochemical sensitizer, whereby the polyolefin is oxidized to introduce hydroperoxide into the polymer side chain, and finally a carbonyl group is produced. Thus, it has a function of promoting the disintegration of the polyolefin by photolysis of the ketone.

The polyolefin resin in the present invention includes polyethylene, polypropylene, poly (4-methyl-1-pentene), polystyrene and the like, and further forms a graft copolymer of the above-mentioned polymer and another vinyl polymer, or the above-mentioned polymer. There are copolymers of the obtained monomers and other vinyl monomers, blended products of the (co) polymers, and the like. Further, copolymers containing nylon, polyester, polyvinyl chloride, polyacrylonitrile, and monomers capable of forming these polymers as copolymerization components are also effective.

The phosphorus-containing metal complex is contained in the composition in an amount capable of decomposing the polyolefin when the molded article of the polyolefin composition containing the complex is irradiated with light. The amount thereof varies depending on the type of the polyolefin resin, the type of the phosphorus-containing metal complex, the desired decomposition time, etc., but is usually 0.0001 to 5 parts by weight, preferably 0.001 to 1 part by weight, relative to 100 parts by weight of the polyolefin resin. .. The polyolefin resin molded article according to the present invention, the disintegration rate when it is left outdoors to disintegrate is largely dependent on the conditions at that time, but is generally determined by the addition amount of the phosphorus-containing metal complex, It is important to determine in advance the amount of addition that is commensurate with the predetermined time of disintegration according to the application.

As described above, since the amount of the phosphorus-containing metal complex is extremely small, the molding conditions are such that extrusion, inflation and other usual manufacturing methods are used, the physical properties of the molded product are not impaired, and the cost of the molded product is low. It can be kept cheap.

When a molded article is prepared using the photodegradable polyolefin resin composition of the present invention, for example, i) a phosphorus-containing metal complex is directly directly mixed with a polyolefin resin in a kneader such as a roll, Banbury, or kneader. Alternatively, a method of melt-kneading with an extruder or the like; ii) a method of previously mixing with a polyolefin resin with a Henschel mixer or the like to improve dispersion of the phosphorus-containing metal complex, and then melt-kneading with a kneader or an extruder by the above-described method; Alternatively, various known methods can be used, including iii) a method of once preparing a master batch of a high-concentration phosphorus-containing metal complex and then kneading with a polyolefin resin in the above kneader or extruder.

Since the above-mentioned complex used in the present invention also functions as a thermal antioxidant, a thermal antioxidant is not particularly required, but other antioxidants may be contained depending on the case.
Further, other compounding agents such as a stabilizer, a plasticizer, a foaming agent, a lubricant, an antistatic agent, an antistatic agent, a filler or a coloring agent of an organic pigment or an inorganic pigment can significantly enhance the effects of the present invention. It may be contained to the extent that it is not damaged.

Of the above phosphorus-containing metal complexes, iron or copper complexes are particularly effective in promoting photodegradation. On the other hand, since the nickel complex has a large effect of photostability, it deviates from the object of the present invention.

[0020]

EXAMPLES Examples will be described below, but the present invention is not limited to the scope of these examples.

Example 1 Commercially available low density polyethylene 10
In 0 part by weight, a phosphorus-containing metal complex of the following formula (II) (No.
0.2 parts by weight of the compound shown by 4) was added and kneaded sufficiently at about 160 ° C.

[0022]

[Chemical 3]

The kneaded product was molded into a thin film having a thickness of 70 μm by a compression molding machine or an extrusion molding machine inflation device. Separately, a film containing no phosphorus-containing metal complex (standard film) was prepared. The film containing the phosphorus-containing metal complex has no change in the initial physical properties of tensile strength and elongation as compared with the standard film (here, "there is no change in the initial physical property" is as described above). Shows that the physical properties of the obtained film at the time of preparation are the same as those of the standard film at the time of preparation), and the physical properties after being left for 60 days in a room equipped with an ordinary fluorescent lamp. It was almost the same as before leaving it. next,
The newly created film was put on a due panel light control weather meter, the film was taken out at regular intervals, the elongation percentage of the film was measured, and the elongation remaining percentage was calculated. The method for measuring the elongation rate and the method for calculating the elongation remaining rate are shown below.

(Elongation rate) Elongation rate refers to the ratio of the elongation when the film piece of the material is pulled in the longitudinal direction to the original length, and according to JIS K 6781, Shimadzu Autograph AG-A (computer measurement Control precision universal testing machine), chuck distance 10 cm, width 1 cm, pulling speed 500 mm / min. It is calculated by the following formula.

[0025]

[Equation 1]

(Elongation Residual Rate) The elongation rate is measured before the film is subjected to the due panel light control weather meter (before the weather resistance test) (0 hours). Then, this film was subjected to a weather resistance test by applying a weather meter for a predetermined time (x hours). Later measure the elongation again,
The ratio (%) of the elongation rate at this time to the elongation rate before the test is defined as the elongation remaining rate. The residual elongation rate is calculated by the following formula.

[0027]

[Equation 2]

The above results are shown in Table 2. In Table 2 ☆
Indicates that the film was pulverized or ruptured during the weather resistance test or during the measurement of the residual elongation rate, and the subsequent weather resistance test or the residual elongation rate measurement became impossible.

(Examples 2 to 4) As a phosphorus-containing metal complex,
A film was obtained in the same manner as in Example 1 except that the compounds shown in Table 2 were added in the amount shown in Table 2. The initial physical properties of the obtained film did not change at all, and the physical properties after being left for 60 days in a room equipped with an ordinary fluorescent lamp were almost the same as those before being left. The elongation residual ratio of these films was measured by the same method as in Example 1. The results are shown in Table 2.

(Examples 5 and 6) The same as Example 1 except that a commercially available polypropylene was used in place of the low density polyethylene, and the compound shown in Table 2 was added as the phosphorus-containing metal complex in the number shown in Table 2. To obtain a film.
The temperature at the time of kneading the polypropylene and the phosphorus-containing metal complex was about 170 ° C. The initial physical properties of the obtained film did not change at all, and it was 60 in a room equipped with an ordinary fluorescent lamp.
The physical properties after leaving for a day were almost the same as those before leaving. The elongation residual ratio of these films was measured by the same method as in Example 1. The results are shown in Table 2.

Example 7 Example 1 was repeated except that a commercially available impact-resistant polystyrene was used in place of the low-density polyethylene and the compound shown in Table 2 was added as the phosphorus-containing metal complex in the number shown in Table 2. A film was obtained in the same manner. The temperature when kneading polystyrene and phosphorus-containing metal complex is about 18
It was set to 0 ° C. The initial physical properties of the obtained film did not change at all, and the physical properties after being left for 60 days in a room equipped with an ordinary fluorescent lamp were almost the same as those before being left. The elongation residual ratio of these films was measured by the same method as in Example 1. The results are shown in Table 2.

Comparative Example 1 A film was obtained by kneading and molding in the same manner as in Example 1 without adding a phosphorus-containing metal complex to a commercially available low density polyethylene. The physical properties of the film after being left for 60 days in a room equipped with an ordinary fluorescent lamp were almost the same as those before being left. The elongation residual ratio of this film was measured by the same method as in Example 1. The results are shown in Table 3. In Table 3, a star indicates that the film was pulverized or ruptured during the weather resistance test or the measurement of the elongation residual ratio, and the subsequent weather resistance test or the elongation residual ratio measurement became impossible.

Comparative Example 2 A film was obtained in the same manner as in Example 1 except that 0.3 part by weight of the dimethyldithiocarbamate iron complex was used instead of the phosphorus-containing metal complex.
When the initial physical properties of the obtained film were examined, the elongation remaining ratio was 91%. 60 in a room with normal fluorescent lights
The physical properties after leaving for a day were almost the same as those before leaving. The elongation residual ratio of this film was measured by the same method as in Example 1. The results are shown in Table 3.

Comparative Example 3 A film was obtained in the same manner as in Example 1 except that 0.3 part by weight of nickel diphenyldithiophosphinate complex was used instead of the phosphorus-containing metal complex. There is no change in the initial physical properties of the obtained film,
Further, the physical properties after being left for 60 days in a room equipped with an ordinary fluorescent lamp were almost the same as those before being left. The elongation residual ratio of this film was measured by the same method as in Example 1.
The results are shown in Table 3.

Comparative Example 4 Comparative Example 1 except that commercial polypropylene was used instead of low density polyethylene.
A film was obtained in the same manner as in. The physical properties of the film after being left for 60 days in a room equipped with an ordinary fluorescent lamp were almost the same as those before being left. About this film Example 1
The elongation remaining ratio was measured in the same manner as in. The results are shown in Table 3.
Shown in.

Comparative Example 5 A film was obtained in the same manner as in Comparative Example 1 except that a commercially available high impact polystyrene was used in place of the low density polyethylene. The physical properties of the film after being left for 60 days in a room equipped with an ordinary fluorescent lamp were almost the same as those before being left. The elongation residual ratio of this film was measured by the same method as in Example 1. The results are shown in Table 3.

[0037]

[Table 2]

[0038]

[Table 3]

In Table 3, phosphorus-containing metal complexes * 1 and *
2 represents the following compounds, respectively.

[0040]

[Chemical 4]

It can be seen from Table 2 that the film containing the phosphorus-containing metal complex of the present invention disintegrates in an extremely short period when left under natural outdoor conditions. On the other hand, from Table 3, it can be seen that all the films containing no phosphorus-containing metal complex disintegrate very slowly. Although the film to which the dimethyldithiocarbamate iron complex was added (Comparative Example 2) showed relatively good disintegration, it was still insufficient, and conversely, the film to which the nickel diphenyldithiophosphinate complex was added (Comparative Example 3) was used. It is light stable. Thus, these compounds do not act as photodisintegration promoters. As an index showing the degree of deterioration,
Absorption ratio of carbonyl group in infrared absorption spectrum (Abs.1710cm ^-1 /Abs.2030cm ^-1 = carbonyl index)
It was found that only the initial deterioration could be judged, although there was a comparison based on the size of. For reference, the time-dependent changes in the carbonyl index of the films of Examples 2 and 4 and Comparative Examples 1 and 2 upon irradiation with light are shown in FIG.

[0042]

As described above, according to the present invention, when a specific phosphorus-containing metal complex is added to a polyolefin resin in a predetermined ratio, it is stable in indoor use, but exposed to ultraviolet rays or sun rays outdoors. Then, a polyolefin resin composition exhibiting extremely rapid disintegration is obtained. This composition can be widely used for various photo-degradable plastic molded articles.

[Brief description of drawings]

FIG. 1 is a graph showing changes in carbonyl index with time when a film using the photodegradable polyolefin composition of the present invention and a conventional polyolefin resin film were applied to a due panel light control weather meter.

Claims (1)

Claims: 1. With respect to 100 parts by weight of a polyolefin resin,
Phosphorus-containing metal complex represented by the following general formula (I): 0.0001 to 5
Photodegradable polyolefin resin composition containing parts by weight: Here, R ¹ is an alkyl group, an aryl group, or an aralkyl group, R ² is an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an aralkyl group, or an aralkyloxy group, and X ¹ and X ² are respectively Independently O or S, M is Cr, Mn, Fe, Co, C
u, Zn, Zr, W, or Ce, and n is a numerical value of the valence of M.