JP2962531B2 - Photodisintegrable polyolefin resin composition - Google Patents

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 degrades and decomposes very rapidly when exposed to sunlight or ultraviolet rays.

[0002]

2. Description of the Related Art Plastic resins, for example, polyolefin resins such as polyethylene, polypropylene, polyvinyl chloride, and polystyrene are easily melt-molded.
Because of their low cost, they are widely used in the fields of containers, films, sheets, pipes, packaging materials and the like, and the total amount used is increasing.

[0003] However, these plastic resins are extremely stable under natural conditions. In addition, conventional resins have been focused on enhancing durability, and additives such as heat stabilizers, light stabilizers, and light deterioration inhibitors have been added. It takes an extremely long time to be decomposed and reduced into nature.
Therefore, destroying the natural circulation system and polluting the environment has become a social problem.

[0004] In order to solve such a problem, plastics are separated and collected from the garbage and reused. If the plastics cannot be collected, the plastics are burned together with the garbage and used as a heat source. Alternatively, when it is left in the environment as waste, it is preferable to decompose as quickly 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 effect is added to a plastic material and decomposed by irradiation with sunlight or ultraviolet rays.
If the decomposition rate of plastic can be increased,
It is thought that the speed at which plastics left in the environment are naturally reduced will also increase, which will lead to the solution of the problem of environmental pollution. However, preparing such a photodegradable plastic has the disadvantage that expensive additives, for example, must be used in relatively large amounts.

[0006]

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

[0007]

The photo-degradable polyolefin resin composition of the present invention is based on a phosphorus-containing metal complex represented by the following general formula (I) per 100 parts by weight of a polyolefin resin.
0.0001 to 5 parts by weight, thereby achieving the above object.

[0008]

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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 becomes the valence of M.

[0010] Of the phosphorus-containing metal complexes used in the present invention, commonly used compounds are shown in Table 1.

[0011]

[Table 1]

[0012] The above-mentioned phosphorus-containing metal complex is selected from the group consisting of Organophosphor
usCompounds , 2nd edn, Kosolapoff, GMand Maier, L., V
ols 1-7, Wiley, New York, 1972-76, etc. For example, the compound represented by 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 (where P
h represents a phenyl group. ) And reacting it with FeCl ₃ or the like.

The above-mentioned phosphorus-containing metal complex is activated by light energy 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 formed. Thus, it has an action of accelerating the disintegration of polyolefin by ketone photolysis.

The polyolefin resin in the present invention includes polyethylene, polypropylene, poly (4-methyl-1-pentene), polystyrene and the like. Further, a graft copolymer of the above polymer and another vinyl polymer, and the above polymer are formed. Copolymers of the resulting monomer with other vinyl monomers, blends of the above (co) polymers, and the like. In addition, nylon, polyester, polyvinyl chloride, polyacrylonitrile, etc.
Blend comprising a blending component with the polymer, to a <br/> Rabbi, Po polyvinyl chloride, a monomer capable of forming a polyacrylonitrile, polyethylene, polypropylene, poly (4-methyl-1-pentene), polystyrene and the like A copolymer with a monomer that can be formed is also effective, and is included in the scope of the polyolefin resin in the present invention.

[0015] 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 varies depending on the type of the polyolefin resin, the type of the phosphorus-containing metal complex, the desired decomposition time, and the like, but is usually 0.0001 to 5 parts by weight, preferably 0.001 to 1 part by weight, based on 100 parts by weight of the polyolefin resin. . The disintegration rate when the polyolefin resin molded article according to the present invention is left outdoors and disintegrated largely depends on the conditions at that time, but is generally determined by the amount of the phosphorus-containing metal complex to be added. It is important to determine in advance the amount of addition that is commensurate with the predetermined time for disintegration according to the application.

As described above, since the amount of the phosphorus-containing metal complex can be extremely small, the molding conditions are the same as those of ordinary production methods such as extrusion and inflation, and the physical properties of the molded product are not impaired and the cost of the molded product is reduced. It can be kept cheap.

When a molded article is prepared using the photo-degradable polyolefin resin composition of the present invention, for example, i) a kneading machine such as a roll, a Banbury, a kneader, etc., directly containing the phosphorus-containing metal complex together with the polyolefin resin; Or 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 in order to improve the dispersion of the phosphorus-containing metal complex, and then melt-kneading with a kneader or an extruder according to the method described above; Alternatively, various known methods can be used, including a method in which a master batch of a phosphorus-containing metal complex having a high concentration is once prepared and then kneaded with a polyolefin resin in the above kneader or extruder.

Since the complex used in the present invention also functions as a thermal antioxidant, it does not require a thermal antioxidant, but may contain other antioxidants in some cases.
Further, other compounding agents, for example, stabilizers, plasticizers, foaming agents, lubricants, antistatic agents, antiblocking agents, fillers or organic pigments, coloring agents for inorganic pigments, etc., significantly enhance the effects of the present invention. It may be contained to the extent that it is not impaired.

Among the above-mentioned phosphorus-containing metal complexes, particularly, iron or copper complexes have a large effect of promoting photodisintegration. On the other hand, the nickel complex has a large light stability effect, and thus departs from the object of the present invention.

[0020]

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

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

[0022]

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The above kneaded material was formed 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 (standard film) containing no phosphorus-containing metal complex was prepared. The film containing the phosphorus-containing metal complex has no change in the initial physical properties of the tensile strength and the elongation percentage as compared with the standard film (here, “there is no change in the initial physical properties” as described above) Shows that the physical properties of the resulting film at the time of preparation are unchanged compared to those of the standard film at the time of preparation), and the physical properties of the film after being left for 60 days in a room with a normal fluorescent lamp. Was almost the same as before. next,
The newly prepared film was applied to a Dew panel light control weather meter, the film was taken out at regular intervals, the elongation percentage of the film was measured, and the elongation residual rate was calculated. Hereinafter, a method for measuring the elongation and a method for calculating the residual elongation will be described.

(Elongation) The elongation refers to the ratio of the elongation to the original length when a film piece of a material is pulled in the longitudinal direction, and is a Shimadzu Autograph AG-A (computer measurement) according to JIS K6781. Controlled precision universal testing machine), the distance between the chucks was 10 cm, the width was 1 cm, and the tensile speed was 500 mm / min. And is calculated by the following equation.

[0025]

(Equation 1)

(Elongation Residual) The elongation is measured before applying the film to the above-mentioned due panel light control weather meter (before the weather resistance test) (0 hour). Next, the film was subjected to a weather resistance test by applying a weather meter for a predetermined time (x hours). Later, the elongation was measured again,
The ratio (%) of the elongation rate to the elongation rate before the test is defined as the elongation residual rate. The residual elongation is calculated by the following equation.

[0027]

(Equation 2)

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

Examples 2 to 4 As phosphorus-containing metal complexes,
A film was obtained in the same manner as in Example 1 except that the compounds shown in Table 2 were added in the number shown in Table 2. The initial physical properties of the obtained film were not changed at all, and the physical properties after being left in a room with a usual fluorescent lamp for 60 days were almost the same as before. The elongation residual ratio of these films was measured in the same manner as in Example 1. Table 2 shows the results.

(Examples 5 and 6) Same as Example 1 except that commercially available polypropylene was used in place of the low-density polyethylene and the compounds shown in Table 2 were 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 the film was not treated in a room with a normal fluorescent lamp.
The physical properties after standing for the day were almost the same as before. The elongation residual ratio of these films was measured in the same manner as in Example 1. Table 2 shows the results.

Example 7 Commercially available high-impact polystyrene was used in place of low-density polyethylene, and the compound shown in Table 2 was added as a phosphorus-containing metal complex in the same number as in Example 2 except that the number of parts shown in Table 2 was added. A film was obtained in the same manner. The temperature at the time of kneading the polystyrene and the phosphorus-containing metal complex is about 18
0 ° C. The initial physical properties of the obtained film were not changed at all, and the physical properties after being left in a room with a usual fluorescent lamp for 60 days were almost the same as before. The elongation residual ratio of these films was measured in the same manner as in Example 1. Table 2 shows the results.

Comparative Example 1 A commercially available low-density polyethylene was kneaded and molded in the same manner as in Example 1 without adding a phosphorus-containing metal complex to obtain a film. The physical properties of the film after being left for 60 days in a room with a normal fluorescent lamp were almost the same as before. The elongation residual rate of this film was measured in the same manner as in Example 1. Table 3 shows the results. In Table 3, ☆ indicates that the film was powdered or broken during the weather resistance test or the measurement of the residual elongation, so that the subsequent weather resistance test or measurement of the residual elongation became impossible.

Comparative Example 2 A film was obtained in the same manner as in Example 1, except that 0.3 parts by weight of a dimethyldithiocarbamate iron complex was used instead of the phosphorus-containing metal complex.
When the initial physical properties of the obtained film were examined, the residual elongation was 91%. 60 indoors with a normal fluorescent light
The physical properties after standing for the day were almost the same as before. The elongation residual rate of this film was measured in the same manner as in Example 1. Table 3 shows the results.

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

Comparative Example 4 Comparative Example 1 was repeated except that a commercially available polypropylene was used instead of the low density polyethylene.
A film was obtained in the same manner as described above. The physical properties of the film after being left for 60 days in a room with a normal fluorescent lamp were almost the same as before. Example 1 of this film
The elongation residual rate was measured in the same manner as in the above. Table 3 shows the results.
Shown in

Comparative Example 5 A film was obtained in the same manner as in Comparative Example 1, except that a commercially available impact-resistant polystyrene was used instead of the low-density polyethylene. The physical properties of the film after being left for 60 days in a room with a normal fluorescent lamp were almost the same as before. The elongation residual rate of this film was measured in the same manner as in Example 1. Table 3 shows the results.

[0037]

[Table 2]

[0038]

[Table 3]

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

[0040]

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From Table 2, it can be seen that the film containing the phosphorus-containing metal complex of the present invention collapses in a very short time when left under outdoor natural conditions. On the other hand, from Table 3, it can be seen that all of the films containing no phosphorus-containing metal complex disintegrate very slowly. The film to which the dimethyldithiocarbamate iron complex was added (Comparative Example 2) showed relatively good disintegration, but it was still insufficient, and conversely, the film to which the nickel diphenyldithiophosphinate complex was added (Comparative Example 3). Has light stability. Thus, these compounds do not act as photodisintegration promoters. As an index indicating the degree of deterioration,
Absorption ratio of carbonyl group in infrared absorption spectrum (Abs. 1710 cm ^{-1 /} Abs. 2030 cm ^-1 = carbonyl index)
Although there was a comparison based on the magnitude of the above, it was found that only the initial deterioration could be determined. For reference, FIG. 1 shows the time-dependent changes in the carbonyl index of the films of Examples 2 and 4 and Comparative Examples 1 and 2 during light irradiation.

[0042]

According to the present invention, when a specific phosphorus-containing metal complex is added to a polyolefin resin at a predetermined ratio, it is stable for indoor use, but is not exposed to outdoor ultraviolet rays or sunlight. A polyolefin resin composition exhibiting extremely rapid disintegration can be obtained. This composition can be widely used for various photodegradable plastic molded articles.

[Brief description of the drawings]

FIG. 1 is a graph showing the time-dependent changes in the respective carbonyl indices when a film using the photodegradable polyolefin composition of the present invention and a conventional polyolefin resin film are subjected to a Dupanel light control weather meter.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-47-3338 (JP, A) JP-A-50-100141 (JP, A) JP-A-48-17842 (JP, A) 17887 (JP, B1) (58) Field surveyed (Int. Cl. ⁶ , DB name) C08L 23/00-23/36

Claims (1)

(57) [Claims] (1) 100 parts by weight of a polyolefin resin,
0.0001 to 5 phosphorus-containing metal complexes represented by the following general formula (I)
Photodegradable polyolefin resin composition containing parts by weight: Wherein 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 aralkyl group,, X ¹ and X ² are each Independently O or S, M is Cr, Mn, Fe, Co, C
u, Zn, Zr, W, or Ce; and n is a numerical value that is the valence of M.