KR100725754B1 - Fully biodegradable master batch with photodegradability introduced by reacting with oxygen, and its pla composite - Google Patents

Abstract

Provided are a method for preparing a biodegradable master batch, a biodegradable master batch prepared by the method which can be degraded by light, and a resin composition containing the master batch. A method comprises the steps of preparing a chip from a powder composition comprising an inorganic or organic additive and a biodegradable polycaprolactone as a matrix polymer in a ratio of 70:30 to 15:85 by weight, and introducing it into a compounding machine; injecting the air containing oxygen to the mixture with a velocity of 0.1-3 cm^3/sec through an air injection hole; and immediately cutting the extruded product discharged from the compounding machine into a form of chip, cooling it with air, and sealing and packaging it.

Description

Fully biodegradable master batch production method with photodegradation function induced by using oxygen reaction and polylactide resin composition containing same {Fully biodegradable master batch with photodegradability introduced by reacting with oxygen, and its PLA composite}

1 is a graph showing an infrared spectrogram of a master batch (M / B) of the present invention.

Figure 2 is a biaxial extrusion compounding machine screw combination diagram for manufacturing a master batch (M / B) of the present invention.

Figure 3 is a view showing a biaxial extrusion compounding machine used to manufacture the master batch (M / B) of the present invention.

The present invention relates to a method for producing M / B for imparting photodegradation function to a fully biodegradable resin composition and to a polylactide resin composition comprising M / B prepared for application to films, sheets, and moldings.

In general, disposable films, sheets, and moldings used as non-degradable polymers are disposed of in a contaminated state depending on the intended use, and thus have to undergo a cleaning process for recycling, resulting in secondary pollution such as water environmental pollution. In addition, incineration may cause fatal air pollutants such as dioxins as well as incinerator damage due to high calorific value of the polymer. Therefore, in order to solve these problems, research into alternative biodegradable polymers has been actively conducted.

However, films, sheets, and moldings made from these fully biodegradable polymers also cannot fully take advantage of biodegradation when placed in a special environment that lacks biodegradation conditions, i. In particular, marine-related disposable products, agricultural mulching film, etc. are required for both biodegradation and photolysis at the same time. Therefore, in order to fundamentally solve the environmental pollution of non-degradable plastics used as various disposable products, a completely biodegradable resin composition having photodegradation properties is urgently needed.

The present invention has been made in view of the above-described demands, and an object of the present invention is to provide a method for producing a fully biodegradable master batch provided with photodegradation properties and a polylactide resin composition containing the same.

The present invention for achieving the above object provides a method for producing a fully biodegradable master batch (hereinafter referred to as "M / B") endowed with photodegradation characteristics and a polylactide resin composition containing the same.

The present invention uses oxygen in the air together with a reaction initiator to induce carboxyl or hydroperoxide compounds, which are photosensitive groups that absorb ultraviolet energy in natural light to biodegradable polymers that are decomposed by natural microorganisms. It is a harmless, very simple and inexpensive way to give photodegradation performance by means of injection.

Conventional methods copolymerize photosensitive group monomers or blend photodegradable additives when polymerizing non-degradable polymers, which cannot ignore the extra cost and the potential for unreacted materials.

On the other hand, the present invention is a simple, very efficient and harmless environment-friendly method in which oxygen in the air is naturally generated when the oxygen in the air is introduced into the natural phenomenon occurring during the manufacturing process of M / B. The prepared M / B is an invention for preparing and applying a resin composition having both photodegradability and biodegradability by blending with polylactide, which is a fully biodegradable polymer.

In general, a method for producing a degradable plastic can be divided into two types, photodegradable and biodegradable. Biodegradable polymer refers to a substance that is modified or degraded by a microorganism or an enzyme produced by the microorganism. Commercially available biodegradable polymers include Polylactide (PLA) from NatureWalk, a natural polymer from corn starch, Poly (hydrobutyrate-co-hydroxyvalerate) from IC, a petrochemical raw material from microbial polymers, and Polycaprolatone from Union Carbide ( PCL) is the most famous.

Recent references to fully biodegradable plastics include: U.S. Pat.No. 5512617, U.S. Pat.No.5599858, U.S. Pat.No.5609677, U.S. Pat.No.5681873, U.S. Pat.No.5693321, U.S. Pat.No. Patent 5656721, U.S. Pat.5678324, U.S. Pat.No.5644020, U.S. Pat.No.5639518, U.S. Pat.No.5637631, U.S. Pat.

Disposable products made of these biodegradable polymers can be collected and composted after use, but when used in nature, especially when used as aquatic living area, marine and agricultural mulching film, photodegradation properties are also necessary.

Therefore, in the present invention, polycaprolactone (PCL) of Union Carbide Co., Ltd. was used as a matrix polymer to prepare M / B with added photodegradable properties. In the present invention, polylactide is not used as a matrix for M / B production because polylactide (PLA) has a relatively high processing temperature and hydrolysis is difficult to control moisture. In addition, the processing window (processing window range) is narrow, the rapid molecular weight decrease occurs during M / B manufacturing is not suitable for M / B. In contrast, polycaprolactone has a low melting point and viscosity, and a wide processing window, thereby preventing excessive decomposition of the matrix during M / B manufacturing.

Photodegradable polymer refers to a polymer that is decomposed by breaking the polymer ring by the ultraviolet ray energy of the sun, the physical properties of the polymer and ultimately the molecular weight. In order to give such photodegradability to existing plastics, the method of mixing photolysis M / B is usually used. In the present invention, it is intended to produce photodegradable and biodegradable M / B, and also to prepare photodegradable and fully biodegradable resin compositions using the same.

In the present invention, however, photodegradability is given to the biodegradable polymer in a completely different manner from the conventional method of showing M / B having photodegradation performance below to manufacture photodegradation and fully biodegradable M / B.

Conventional photolysis M / B manufacturing methods are classified into three categories.

Firstly, the metal ion-based polymer M / B is a method of transition metals such as iron, nickel, cadmium, and cobalt, and TiO ₂ as a photo-oxidation accelerator. Transition metals facilitate the photooxidation of oxygen in weak parts of the polymer main chain, resulting in peroxads, hydroperoxides, or carboxyl compounds in the polymer main chain, which are decomposed by ultraviolet light in the atmosphere. Is disclosed in US Pat. No. 4,440,311.

This method has the advantage of using the existing compounding method (compounding or mixing), but since the transition metals are added, these metals accumulate after decomposition and should be tested for the effects on animals and plants. The disadvantage is that it is limited.

Secondly, the method of US Pat. No. 3,753,52 is a method of polymerizing a vinyl ketone monomer as described below using a conventional polymer synthesis method.

Wherein R, R 'are hydrogen, methylene, ethylene, phenyl and the like (B. Baum and R. A. White, "Polymers and Ecological Problems", Pleunum Press, N.Y. p45-60 (1973)). This method has a disadvantage in that the production of vinyl ketone monomers is difficult, but photolysis is known to occur relatively well. That's because light-sensitive ketone groups are attached laterally (Macromolecules, 17, 2830 (1984)).

The third method is a method registered in US Pat. Nos. 2495286 and 3825620, in which carbon monoxide (CO) is bonded to a polymer main chain in a high temperature and high pressure reaction vessel. The chemical structural formula is as follows.

It is known here that ketone groups are introduced into the main chain, which slightly degrades the photodegradability. In addition, a method of introducing ketone carboxyl groups into the main chain and oxidizing the photoactivated NOCl with polyethylene and then hydrolyzing with oxime (CNOH) is known (J. of Appl. Polym. Sci., Vol. 19, 923 (1975).

In the present invention, a photosensitive group carboxyl group is introduced into polycaprolactone (PCL), which is a fully biodegradable polymer, to prepare M / B capable of both photolysis and biodegradation. The mechanism for introducing the Sensitivity Group is as described below. In other words, the mechanism for generating radicals and then carboxyl groups by mechanical mastication alone or by addition of a reaction initiator is as follows (W. Schnabel, "Polymer Degradation: Principles and Applications", Hanser International , p. 64-94 (1981), JF Rabek, "Photostabilization of Polymers: Principles and Applications", Elsevier Applied Science, New York, p. 2-17 (1990)). When polycaprolactone (hereinafter referred to as 'PCL') chain is subjected to shear stress or normal stress (normal stress or elongational stress) by mechanical force, PCL generates polymer radicals as shown in the formula (1). Alternatively, when a reaction initiator is used, radicals are more easily formed by heat, and the radicals remove hydrogen from the PCL chain to form a polymer radical of formula (1). The polymer radical of the formula (1) means both the main chain end group and the radical in the chain. The radicalization by mechanical force is represented by the abbreviation P of polymer because the molecular weight is still at the polymer level even if the PCL chain is divided into two.

These polymer radicals (P.) cause oxidation with oxygen in the immediate surroundings to produce peroxide radicals such as (2).

These polymer peroxide radicals take away the hydrogen groups of other polymers around them to produce hydroperoxides and other polymer radicals (see Eq. (3)), and the resulting polymer radicals react with oxygen to form polymer peroxide radicals. At this time, since the supply of oxygen is a rate step of generating the polymer peroxide, the addition of calcium carbonate or other inorganic additives increases the permeability of oxygen, thereby increasing the production rate of the polymer peroxide radical. The subsequent reaction is the same as (3).

Here, POO · is a polymer peroxide radical as in formula (2), and the polymer radical (P ·) in (3) reacts with oxygen again to produce a polymer peroxide radical as in formula (2).

The polymer hydroperoxide produced as shown in Equation (3) is very active and generates polymer oxy radicals and hydroxy radicals as shown in Equation (4) easily by light or heat.

The hydroxy radical generated in the formula (4) again generates a polymer radical as shown in the formula (5), the generated radical generates the polymer peroxide radical as shown in the formula (2), and the reaction follows the formula (3) after.

The polymer oxy radical (PO.) Made in formula (4) generates terminal aldehydes as in formula (6) or forms main chain ketone groups as in formula (7).

The polymer radical (P.) generated here follows the reaction after formula (2), and the low molecular radical (R.) acts as an initiator to continue the ketone group formation reaction. R is a low-molecular compound having 0 to 12 carbon atoms, such as hydrogen, methyl, ethyl, phenyl, and a reaction initiator. The final reaction of these generated radicals is the main chain ketone group introduction type as shown in equation (8), the crosslinking as shown in equation (9), or the polymer having the main chain ketone group as shown in equation (10). Hydrogen peroxide, such as formula (11), is produced to repeat the reaction after formula (4).

Among the reaction mechanisms mentioned above, the key molecular structure of the photocatalytic and biodegradation oxidation-promoting additives is the introduction of ketone or ketone carboxyl groups such as the formulas (6), (7), (8), (9), and (10). Depends on what you do Existing methods are a method of polymerizing a chemical copolymer or adding a photocatalyst such as a transition metal to assist the oxidation reaction as in (2). In the present invention, it is essential to generate the polymer radicals such as the formula (1) in order to cause the oxidizing action of the formula (3), and melt the PCL polymer at a suitable temperature, and then use a high-speed super mixer equipped with a heating device. When rotating at a rotational speed of about 500-3000 revolutions per minute, molecules are easily broken by stress, resulting in polymer radicals as shown in (1). Adding a small amount of the reaction initiator can form a photosensitive group more effectively.

An important technique for the oxidation of polymer radicals in the present invention is the permeability of oxygen. Oxygen permeability of plastic is so low that it is impossible to supply enough oxygen in M / B process time. Therefore, there is a need for a technology that smoothly supplies oxygen into the melt.

This method adds inorganic or organic additives such as talc, calcium carbonate, natural zeolite, quicklime, titanium oxide starch, fine natural powder, etc. so that the introduced air can be easily and evenly diffused into the melt. The present invention shows a significant difference in the purpose and function with conventional mineral M / B. The purpose of the existing inorganic M / B is made for the purpose of price control and some mechanical properties control has little photolysis function. However, a high content of calcium carbonate mineral M / B is produced a little ketone group due to the air remaining in the inorganic input, but its amount is insufficient, it is difficult to exert a colytic function.

In the present invention, when the M / B prepared to confirm the generation of the ketone group by mechanical method in the infrared spectroscopy was confirmed that the presence of the polymer hydroperoxide of the compound with a wavelength of 920 cm ^-1 absorption band, and also 1720 and By confirming the presence of a ketone carboxyl group with a 1430 cm ^-1 absorption band, it can be demonstrated that the mechanical method in the present invention can introduce carboxyl compounds essential for photodegradable M / B development (see FIG. 1). .

In addition, these films were exposed to natural light in order to demonstrate photodegradation by adding M / B, and the degree of photodegradation according to light exposure time was measured through mechanical strength, surface magnification, intrinsic viscosity measurement, and thermal analysis. , Biodegradability was confirmed by the composting method of ISO 14855.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited by them in any way.

The M / B manufacturing process, the film manufacturing process for photodegradation and biodegradability evaluation and the biodegradation photodegradation evaluation method made by applying very strong stress used in the present invention are described below.

<M / B manufacturing process: introduction of ketone or ketone carboxyl group>

The biodegradable polymer PCL and inorganic or organic additives, which are necessary for M / B production, are mixed in a weight percent of 70:30 to 15:85, and then mixed in a chip and powder in a tumbler, and then introduced into the compounding machine. do. In this process, 0.1-3 parts by weight of a reaction initiator may be added to increase the reaction effect. Compounding can use all existing polymer kneaders. Examples are thermostatic supermixes, bamboo mixes, kneaders and twin screw extruders. In the present invention, a twin screw extruder mixer was used. The screw arrangement of the twin screw extruder increased the mixing efficiency and the production efficiency of the photosensitive group by making the kneading area into two areas (see FIG. 2). The air was installed with an air inlet just after the hopper (see Figure 3). The flow rate of the input air was 0.1-3 cm ³ per second. The melt from the dies of the compounding machine is cut into chips directly from the die, air-cooled and dry sealed.

Ketone or ketone carboxyl group formation, a photodegradable characteristic group, was determined by the presence and intensity of absorption bands around 1640 cm ^-1 and 1700 cm ^-1 using infrared spectroscopy.

<Production of Polylactide Resin Composition>

The prepared M / B compounded the resin composition with the dried polylactide up to 5-90% by weight according to the purpose by using a twin screw extruder used in the production of M / B to prepare a resin composition. Screw structure reduces kneading and hydrolysis of unneeded polymers by uniting the kneading zones into one. The composition is prepared in the form of a chip.

<Film Manufacturing Process>

The polylactide resin composition prepared by the above method was used to prepare a film having a thickness of 0.03 mm using an inflation film maker.

<Evaluation of Photodegradability of PLA Resin Composition Film>

The photodegradation evaluation was performed by exposing the film prepared above to outdoor summer standard natural light (place; on campus in Daedong Yeungnam University, Gyeongsan-si, Gyeongsangbuk-do) to measure the time when the tensile strength and elastic modulus retention at the breaking point was 5% or less. Here, the retention rate is 100% when the light exposure time is 0 hours.

<Biodegradability Evaluation>

The biodegradable measuring device was constructed based on ISO 14855. The biodegradable side suitability can be largely divided into a device in a chamber and an external device. The device outside the thermostat has an air compressor to provide a constant supply of air, and a hose for supplying air is connected into the thermostat. The temperature in the chamber is designed to maintain 58 ± 2 ℃. In the chamber, the sample is mixed with compost, which is an inoculum, for decomposition. Before supplying air to the main reactor, pre-conditioner 20g / L NaOH solution is used to remove CO ₂ from air and supply it with water to the reactor. The air exiting the reactor is measured by CO ₂ analyzer (SIEMENS, ULTRAMAT 21) to measure the amount of carbon dioxide in the air. And the air flow and temperature until the measurement was measured with a wet gas meter (SHINAGAWA SEIKI Co., W-NK-1A).

The reactor consisted of a total of 39 self-made glass apparatuses of 2.5 L size, and three reactors were placed in one sample to obtain an average value. Eleven samples from a total of 13 samples can be tested, the other two being prepared for blanks and identification samples. Do not put the sample in the blank, just put the inoculum compost. All composts used as inoculum were assumed to have a constant shape and subtracted the blank value from the amount of CO ₂ released from each reactor. Identifiers were prepared to validate the device. Cellulose was used in place of the test sample as the identification material. First, the temperature is kept constant at 58 ± 2 ℃ during the experiment period, and air is constantly supplied to the air compressor (domestic production). The air from the air compressor passes through a flow restrictor (MOTT metallurgical corp.) To a constant supply of each sample vessel. And the experiment was performed by darkening the inside of the constant temperature room. The concentration of carbon dioxide released from each sample vessel is determined by CO ₂ at 12 hour intervals. Measurement was made using an analyzer (SIEMENS, ULTRAMAT 21). The flow rate and temperature of the air passed through to the measurement were measured together to calculate the total cumulative amount of carbon released quantitatively. And shake the container by hand every 7 days and stirred. In the case of cellulose and starch, the shape of the sample was used as it is, and the remainder was cut to a size of 1 cm × 1 cm. And the inoculum was used 300g per moisture level in each reactor, the amount of sample was used 30g per reactor. Pre-condition solution was prepared 350ml per bottle of 20g / L NaOH solution prepared by using the distilled water. Each sample vessel was then filled with about 3/4 to facilitate stirring. Biodegradability was determined by the order (net) the amount of CO ₂ generated in the test sample as a percentage of the theoretical CO ₂ generation amount of the sample.

Example 1-7

For preparation of fully biodegradable M / B with photodegradation function, the weight% ratio of PCL and talc is 15: 85-70: 30, initiator 2,5-bis (tert-butylperoxy) -2,5-dimethyl hexane (Luperox ) 0-3 parts by weight were first mixed with a tumbler, and then introduced into a twin screw extruder to prepare M / B. At this time, the temperature was 100-140 ° C, and the revolutions per minute was 300. 0.1-3 cm ³ / sec of air was introduced through the air inlet. 2,5-bis (tert-butylperoxy) -2,5-dimethyl hexane (Luperox) was used as the initiator, and air was added thereto.

TABLE 1

division Composition (% by weight) Initiator (parts by weight) Air flow rate (cm ³ / sec) Absorption bands near frequencies of 1640 cm ^-1 and 1700 cm ^-1 (o, x) Absorption band strength near 1640 cm ^-1 and 1700 cm ^-1 PCL Talc Example 1 15 85 0 0.0 x x Example 2 15 85 0.3 0.0 o △ (weak) Example 3 15 85 0.0 0.3 o ○ (middle) Example 4 15 85 0.3 0.3 o (Strong) Example 5 15 85 0.3 3 o ■ Example 6 15 85 One 3 o ■ Example 7 70 30 0.3 0.3 o ○

Infrared spectroscopy results of Table 1 (see Fig. 1), it can be seen that the absorption band of the strong ketone group appears when the reaction initiator is added and the air is introduced. It was found that the input amount of the initiator and the air did not significantly affect the predetermined amount or more. The results show that the conventional ketone group monomer input polymerization or the photosensitive group can be induced simply but effectively by the method of the present invention without adding a photosensitive agent. The greater the amount of talc, the better the flow of air, which is considered to be good for the formation of photosensitive groups.

Example 8-11

Table 2 shows the physical properties, photodegradation performance, and biodegradability of the films prepared by adjusting the composition of M / B: PLA prepared in Example 4 and prepared by the inflation film method. For reference, when the general film without photolysis is exposed to natural light for 12 months, the tensile strength retention reaches about 30% and the elongation retention about 20%, and less than that (“Handbook of Polymer Degradation”, SH Hamid, MB Amin, and AG Maadhah Ed., P. 127-259, Marcel Dekker, Inc., New York (1992).

TABLE 2

division Furtherance Tensile Strength (MPa) Elongation (%) Modulus of elasticity (MPa) Time to become less than 5% of initial tensile strength in outdoor exposure Time to become less than 5% of initial tensile strength when composting % Biodegradation after 16 weeks by ISO composting M / B PLA Example 8 10 90 32 4 1500 16 4 58 Example 9 30 70 30 2 1300 13 4 60 Example 10 50 50 15 One 1200 11 3 63 Example 11 70 30 10 One 1000 8 3 65 Comparative Example 1 - - 25 660 220 Many years Over decades 0 Comparative Example 2 - -  28 600 1050 8 Many years 5 Comparative Example 3 0 100 33 4.5 1600 Many years 6 44 Comparative Example 4 25 580 215 Many years Many years 2

Comparative Example 1

Table 2 lists the properties, photodegradation performance, and biodegradability of commercially available low density polyethylene films for comparison with the present invention.

Comparative Example 2

Table 2 lists the physical properties, photodegradation performance, and biodegradability of commercially available photodegradable high density polyethylene films for comparison with the present invention.

Comparative Example 3

Table 2 lists the physical properties, photodegradation performance, and biodegradability of commercially available biodegradable PLA films for comparison with the present invention.

Comparative Example 4

Table 2 lists the physical properties, photodegradation performance, and biodegradability of the biodegradable film of a waste payloader bag containing 30% of commercially available biodegradable materials for comparison with the present invention.

In Table 2, the low-density polyethylene film of the non-degradable polymer of Comparative Example 1 was neither photodegradable nor biodegradable, and the photodegradable high-density polyethylene film of Comparative Example 2 was well decomposed, but little biodegradable. PLA film, which is a biodegradable polymer of Comparative Example 3, was biodegradable but not photodegradable at all. In particular, the biodegradable polymer containing a little starch of Comparative Example 4 did not have both biodegradation and photolysis similar to the non-degradable film. However, the film developed in the present invention, both biodegradation and photolysis occurs, it was possible to adjust the decomposition time according to the composition of the M / B.

As described above, the manufacturing method of M / B according to the present invention is a simple, efficient and human body to naturally generate a photosensitive group having a photodegradation function by introducing oxygen in the air to the natural phenomenon occurring during the M / B manufacturing process It was evaluated to be a harmless environment-friendly manufacturing method.

In addition, the polylactide resin composition containing M / B produced by the present invention was evaluated to be an environmentally friendly resin composition having both photodegradability and biodegradability.

Claims (9)

⒜ a biodegradable polymer polycaprolactone (PCL) as a matrix polymer, the inorganic or organic additives in a weight ratio of 70:30 to 15:85 weight ratio of the polycaprolactone, mixed in a powder form to prepare a chip form Introducing into the compounding machine; 투입 introducing air containing oxygen into the mixture at an air inlet at 0.1 to 3 cm ³ / sec; (B) cutting the melt that has passed through the die of the compounding machine into a chip state immediately at the die, air-cooling, and sealingly packing; Method of producing a biodegradation master batch (M / B) added to the photolysis characteristics comprising a. According to claim 1, wherein the inorganic or organic additive is biodegradation master batch (M) is characterized in that at least one selected from talc, calcium carbonate, natural zeolite, quicklime, titanium oxide starch, fine natural material powder (M) / B) method of preparation. The method of claim 1, wherein the reaction initiator is added and mixed in step (iii) to add the biodegradation master batch (M / B). The method of claim 3, wherein the reaction initiator is 2,5-bis (tert-butylperoxy) -2,5-dimethyl hexane. The method of claim 3, wherein the reaction initiator is added in an amount of 0.1 to 3 parts by weight based on the mixture. According to claim 1, wherein the mixing process using a high-speed mixer equipped with a heating device biodegradation master batch with photodegradation properties, characterized in that performed at a temperature of 100 ~ 140 ℃, 500 ~ 3000 revolutions per minute conditions ( M / B) manufacturing method. delete Biodegradation masterbatch (M / B) added with photodegradation properties made by the method of any one of claims 1 to 6. A resin composition prepared by compounding the master batch (M / B) and polylactide (PLA) of claim 8 in a weight ratio of 5 to 90:95 to 10.

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