JP2003138153A - Photo and biodegradable polymer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a photo and biodegradable polymer composition in which titanium oxide particles is uniformly dispersed without being mutually agglomerated and which keeps inherent transparency of the polymer. SOLUTION: Titanium dioxide whose surface is modified with a or with both saturated or an unsaturated carboxylic acid and a saturated or unsaturated amine. An electron donative group-containing polymer is used as a part of the structure of the polymer so that titanium dioxide in the polymer can be compounded in a nanosize area and the transparency of the polymer composition is kept.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer composition in which titanium dioxide ultrafine particles are combined with a biodegradable polymer, which is decomposed and decomposed by light. Further, the present invention relates to a photo-biodegradable polymer composition which can be used for a molded article such as a film requiring transparency because the biodegradable polymer has original transparency.

[0002]

2. Description of the Related Art Reusing as a recycling is being studied as a countermeasure for a method for treating plastic waste. In parallel with this, the study of decomposing it in the natural environment and returning it to natural recycling is being widely promoted. For example, biodegradable polymers that are decomposed by organisms and microorganisms in soil and sea have come into practical use. More recently,
A method of decomposing by utilizing sunlight has been studied, and ultrafine titanium dioxide particles (1 to 100 nm) are mixed with a biodegradable polymer and self-decomposing and decomposing by sunlight,
So-called photo-biodegradable polymer compositions have also attracted attention and are disclosed in, for example, JP-A-8-1806 and JP-A-9-194692. The method of mixing these titanium dioxides is carried out by mechanical melt kneading, for example, a single-screw and twin-screw extruder,
It is carried out by directly making products using a Banbury mixer, various kneaders, loaders, etc., or once pelletizing.

Although each of the titanium dioxide ultrafine particles having a diameter of 1 to 100 nm is in an invisible region, the surface energy thereof is so large that the particles are easily aggregated, or the aggregated particles are bonded to each other to form large particles. When making a molded product of biodegradable polymer and titanium dioxide,
Aggregation of titanium dioxide is unavoidable and the molded product loses transparency. Therefore, the range of use is limited to the field where transparency is not questioned at all.

[0004]

Therefore, the present invention makes it possible to uniformly disperse titanium dioxide particles in a polymer without agglomerating each other, and a photo-biodegradable polymer composition which does not impair the original transparency of the polymer. It is to provide things.

[0005]

DISCLOSURE OF THE INVENTION As a result of earnest research in view of the above situation, the inventors of the present invention have found that the surface of titanium oxide is a saturated or unsaturated carboxylic acid alone or a saturated or unsaturated carboxylic acid and a saturated or unsaturated amine. Agglomeration between particles can be suppressed by using titanium dioxide ultrafine particles modified by both, and when a polymer containing an electron-donating group as part of the structure of the biodegradable polymer is used, the polymer and titanium dioxide The present inventors have completed the present invention by discovering that fine particles can be composited in the nano-sized region to maintain the original transparency of the polymer.

The present invention will be described in detail below. Titanium dioxide has a photocatalytic ability and decomposes various organic substances that are difficult to decompose into carbon dioxide and water, etc., only by using the light energy of sunlight without using harmful chemicals. In addition, it is a safe and harmless substance, and there is no risk of secondary pollution even if it is discarded. Ultrafine particles generally have a particle size of 1 to 100 nm
Since the surface area is remarkably larger than that of particles having a particle size of 100 nm or more, the photocatalytic ability of each particle is also very high. On the other hand, conversely, as the surface area increases, particles tend to aggregate. In the strongly acidic region in water, H ⁺ is adsorbed on the surface to resist electricity, but a dispersion can be obtained, but it is very difficult to secure stability as ultrafine particles in the vicinity of neutrality and in organic solvents. . The titanium dioxide ultrafine particles used in the present invention are modified with an acidic group or both an acidic group and a basic group in order to suppress aggregation of particles and to ensure dispersibility in an organic solvent. As a result, the dispersibility in the polymer matrix is also very high, and the haze (cloudiness value) change of the composition that does not impair the transparency, more specifically, the 10% by weight titanium dioxide-containing film measured according to JIS K 7105. (ΔH) is 5% or less, preferably 4%, in terms of film thickness of 300 μm, with respect to the film not containing it.
Below, a photo-biodegradable polymer composition having a content of 3% or less is more preferably obtained. The titanium dioxide ultrafine particles used in the present invention are produced by the steps of titanium dioxide ultrafine particle synthesis, ultrafine particle surface acidic group modification, and ultrafine particle surface basic group modification, which will be described below.

<Synthesis of Titanium Dioxide Ultrafine Particles> Titanium dioxide ultrafine particles are produced by hydrolysis of titanium alkoxide or Japane.
se. Journal of Applied Physics, Volume 37, 4603-4
The titanium dioxide ultrafine particle synthesizing method described in 608 page (1998) can be adopted. In the latter case, titanium tetrachloride (TiCl ₄ ) solution is first hydrolyzed, and hydrochloric acid-containing titanium oxychloride (TiOCl ₂ ) obtained therefrom is obtained.
Titanium dioxide is produced by hydrolyzing an aqueous solution or a solution dissolved in a mixed solvent of water and an alcohol such as ethanol. At this time, if a monohydric alcohol such as ethanol or a polyhydric alcohol such as ethylene glycol is added, the reaction is promoted, and finally 1 to 100
It is preferable because ultrafine titanium dioxide particles having a thickness of 10 nm can be obtained. It is considered that this is because alcohol molecules are adsorbed and activated on the surface of the ultrafine titanium dioxide particles that are being produced, and the coating prevents the particle diameter from increasing due to aggregation. Titanium dioxide is separated from the produced titanium dioxide solution by a method such as centrifugation and repeatedly washed with a suitable solvent such as ethyl acetate.

<Modification of Ultrafine Particle Surface with Acidic Group> After washing with ethyl acetate, titanium dioxide is surface-modified with an acidic group. In this process, as the modification of the acidic group progresses, the dispersibility in an organic solvent improves.

The acidic group is a group which releases H ⁺ in water and exhibits acidity, and examples thereof include a carboxyl group, a hydroxyl group and a sulfone group, but a carboxyl group is preferable.
The organic compound having a carboxy group is a saturated or unsaturated carboxylic acid. Examples include acetic acid, propionic acid, acrylic acid, methacrylic acid, hexylic acid, octanoic acid, dodecanoic acid, stearic acid, oleic acid, benzoic acid and the like. As a tendency, as the number of methylene groups increases, it becomes easier to disperse in a solvent having low polarity. The surface-modified titanium dioxide ultrafine particles thus synthesized are first dispersed in an alcohol such as ethanol or 1-butanol. After heating under reflux or ultrasonic chemical treatment, the same amount of a low polar solvent such as toluene is added to change the polarity of the solvent. It is possible to dissolve the desired polymer in this and form the titanium dioxide ultrafine particle / polymer composition.

<Modification of basic group on the surface of ultrafine particles> Titanium dioxide ultrafine particles modified with an acidic group have many active sites. Therefore, depending on the combination with the selected polymer, yellow or red coloring may occur. There is also. To prevent this, the surface is modified with a basic group. The basic group is a group which receives H ⁺ in water and exhibits basicity, and an amino group (amine) is mainly mentioned. For example, a basic modification is made by adding amine to a toluene / 1-butanol solution of ultrafine titanium dioxide particles. To do.

The amines used are alkanolamines such as methylamine, propylamine, hexylamine, dodecylamine and ethanolamine, and saturated or unsaturated aliphatic amines such as allylamine. Dissolution of ultrafine particles in a solvent of low polarity. When dispersion is desired, amines with a large number of methylene groups are selected. The surface-modified product is washed with esters such as ethyl acetate and alcohols such as methanol and ethanol.

Further, the titanium dioxide ultrafine particles whose surface is modified with both acidic groups and basic groups are dispersed in a desired solvent. The solvent used in the present invention can be selected from known ones depending on the type of biodegradable polymer used. For example, aromatic hydrocarbons such as toluene and xylene, chloroform,
Halogenated hydrocarbons such as trichloroethane, ketones such as acetone and methyl ethyl ketone, and N.I.
N-dimethylformamide, N.I. A solvent such as N-dimethylacetamide or dimethylsulfoxide can be used.

Next, the biodegradable polymer used in the present invention means
Examples of the biodegradable polyester include biodegradable polyester, polycarbonate, polyamide, and polyamino acid. Polylactic acid (PLA),
Examples of the biodegradable polycarbonate include polyglycolic acid (PGA), poly, polyhydroxybutyric acid (PHB), polydiglycolic acid butylene, polycaprolactone, polybutylene succinate, and polybutylene succinate / adipate copolymer. As polyethylene carbonate (PEC) and biodegradable polyamide, nylon 4, nylon 2 / nylon 6 copolymer, and biodegradable polyamino acid such as polyaspartic acid can be used. Further, a mixture of two or more of them can also be used. Among them, polylactic acid is particularly preferable in terms of transparency.

<Polymer composition (composite with biodegradable biopolymer)> Separately prepared solution of the biodegradable polymer exemplified above is mixed to obtain titanium dioxide ultrafine particle / polymer mixed solution. If necessary, heating and stirring can be performed in order to promote the complexation of the titanium dioxide ultrafine particles and the polymer. The reason why it is possible to form a composite with a polymer in the nano region is to suppress aggregation of particles by using titanium dioxide ultrafine particles whose surface is modified with a saturated or unsaturated carboxylic acid, a saturated or unsaturated amine, It is believed that this is because it is possible to disperse the above in an organic solvent. Furthermore, since the ultrafine titanium dioxide particles interact with electron-donating groups (ester-bonded oxygen, carbonate-bonded oxygen, amide-bonded oxygen, etc.) in the polymer and cause electron transfer or charge transfer, they do not aggregate. Dispersed one by one in the polymer matrix
It is preferable that the electron-donating group is contained in the polymer structure because it is considered to be complexed.

<Polymer composition (content of titanium dioxide)> The amount to be combined with the polymer is not particularly limited, but the amount to be combined depends on the application to be used and the required photodecomposition rate of the polymer. It can be adjusted appropriately, but 0.001 to 50% by weight, more preferably 0.01 to 30% by weight, still more preferably 0.1 to 1% with respect to the polymer.
0wt% is good. If the compounding amount is large, the mechanical properties inherent to the polymer will be impaired, and if the compounding amount is small, sufficient photodegradability may not be obtained. Therefore, appropriate mixing is performed according to the application. The titanium dioxide ultrafine particles / polymer mixed solution is added to a poor solvent such as hexane, heptane, methanol, etc., and the dried and powdered composition is directly or once pelletized, and then formed into a film or sheet using an extruder. can do.

<Additives> The photo-biodegradable polymer composition according to the present invention has a purpose (for example, moldability, secondary processability, degradability, tensile strength, heat resistance, storage stability, weather resistance, etc.) at the time of molding. Various additives (plasticizer, antioxidant, UV absorber, heat stabilizer, flame retardant, internal release agent, inorganic additive, antistatic agent, surface wetting improver, incineration aid, pigment) ,
Lubricants, natural products) and the like can be added. For example, in inflation molding and T-die extrusion molding, a film,
Inorganic additives and lubricants (aliphatic carboxylic acid amides) can be added in order to prevent blocking and improve the slipperiness of the sheet.

The inorganic additive is not particularly limited,
Examples thereof include silica, calcium carbonate, talc, kaolin, kaolinite, titanium oxide and zinc oxide, and silica and calcium carbonate are particularly preferable. These may be used alone or as a mixture of two or more. As organic additives, starch and its derivatives, cellulose and its derivatives, pulp and its derivatives, paper and its derivatives,
Examples thereof include flour, okara, bran, coconut shell, coffee mash, and protein. These may be used alone or as a mixture of two or more.

<Molded Article and Manufacturing Method Thereof> The photo-biodegradable polymer composition according to the present invention is a suitable material that can be applied to publicly known molding methods, and the obtained molded article is not particularly limited. Examples thereof include films and sheets, monofilaments, multifilaments such as fibers and non-woven fabrics, injection molded articles, blow molded articles, laminates, foams, and thermoformed articles such as vacuum formed articles. Further, the photo-biodegradable composition according to the present invention has a good moldability when stretch-oriented and crystallized, and the effect of the present invention remarkably appears.
It is suitable for the production of sheets, tape yarns, stretch blow molded products and (mono-, multi-) filaments.

The molding method of the molded article obtained from the photo-biodegradable polymer composition according to the present invention includes injection molding method,
Blow molding method (injection stretch blow, extrusion stretch blow, direct blow), balloon method, inflation molding, coextrusion method, calender method, hot press method, solvent casting method, (stretch) extrusion molding, extrusion lamination with paper and aluminum Method, profile extrusion molding, thermoforming such as vacuum (pressure) molding, melt spinning (monofilament,
Multifilament, spun bond method, melt blown method, defibrating yarn method, etc.), foam molding method, compression molding method and the like can be mentioned, and any method can be applied. In particular, extrusion molding,
In the case of a molding method that can take a step of stretch-oriented crystallization such as melt spinning, it is possible to improve the practical strength and appearance such as strength, heat resistance, impact resistance, and transparency of the obtained molded body,
More preferably used. The molded product obtained from the photo-biodegradable composition according to the present invention includes, for example, a molded product obtained by a publicly-known / publicly-used molding method, and there is no limitation on its shape, form, size, thickness and the like. .

<Specific Examples of Applications> Bottles, films or sheets, hollow tubes, laminates, vacuum (pneumatic) molding containers, which are obtained by the molding method of the photo-biodegradable polymer composition according to the present invention, ( Mono, multi) filament, non-woven fabric, foam, shopping bag, paper bag, shrink film, garbage bag, compost bag, lunch box, side dish container, food / confectionery packaging film, food wrap film, cosmetic / cosmetic wrap Film, diapers, sanitary napkins, pharmaceutical wrap films, pharmaceutical wrap films, surgical adhesive medicated wrap films applied to stiff shoulders, sprains, etc., agricultural / horticultural films, agricultural chemical wrap films, greenhouse films, Fertilizer bag, packing band,
Film for packaging magnetic tape cassette products such as video and audio, film for flexible disk (FD) packaging, film for plate making, adhesive tape, tape, yarn, seedling pot, waterproof sheet, bag for sandbags, construction film, weed prevention sheet , Vegetation net, various packaging films for foods, electronics, medical care, medicines, cosmetics, etc., and materials used in the fields of agriculture, civil engineering, fisheries, etc. can be suitably used.

[0021]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the examples.

[0022]

Example 1 Titanium tetrachloride (Wako reagent special grade) 15 ml (0.1
38mol) was weighed into a 200ml three-necked flask in a nitrogen atmosphere, and the reaction system was kept at 0 ° C. Then, 15ml of ion-exchanged water was added drop by drop to obtain yellow oily titanium oxychloride (TiO 2).
A Cl ₂ ) solution (9.2 mol / l) was obtained. A mixture of 600 ml of ethanol and 400 ml of ion-exchanged water was placed in a 1-liter three-necked flask, placed in an oil bath and stirred in a nitrogen atmosphere. After the temperature reached 60 ° C and was stabilized, 4 ml of the TiOCl ₂ solution prepared above was diluted with 36.8 ml of deionized water, and a 1 mol / l TiOCl ₂ solution was added dropwise. After 6 hours, the formed titanium dioxide ultrafine particles were centrifuged and washed with 50 ml of ethyl acetate. After performing the centrifugation and washing operations three times in total, ethyl acetate was removed to obtain titanium dioxide ultrafine particles. Ultrafine titanium dioxide particles were dispersed in 50 ml of acetic acid and stirred at room temperature for 60 hours. The precipitate was centrifuged and washed with ethyl acetate three times. Remove a part of it, depressurize it at 120 ℃, and dry it for 6 hours.
When the infrared spectrum was measured by the tablet method, a carboxylate group (-CO
The thus obtained acetic acid-modified titanium dioxide ultrafine particles (1 g in a dry state) in which a peak of O ⁻ ) was measured was added to 100 ml of 1-butanol in a wet state, and sonication was carried out for 1 hour. . To this, 100 ml of toluene was added to obtain a transparent solution in which ultrafine titanium dioxide particles were uniformly dispersed. After adding 50 ml of n-hexylamine to this solution and stirring for 1 hour, the generated precipitate was collected by centrifugation and washed with methanol and the operation of centrifugation was repeated twice. An aliquot was taken out, dried and subjected to infrared spectrum measurement with a KBr tablet, and it was confirmed that the surface of the titanium dioxide ultrafine particles was modified with both acetic acid and amine. The titanium dioxide ultrafine particles modified with acetic acid / n-hexylamine were added to chloroform.
When added in 40 ml, a uniformly dispersed transparent solution was obtained. Polylactic acid (trade name: LACEA (registered trademark) H-1000
A solution prepared by dissolving 9 g of Mitsui Chemicals, Inc. in 80 ml of chloroform was prepared separately, mixed with the solution of titanium dioxide ultrafine particles, and stirred at room temperature for 30 minutes. The solution was further poured into 500 ml of heptane for reprecipitation, and the precipitate was collected by filtration. After drying the precipitate at 60 ° C for 10 hours,
When the powder was pressed at a pressure of 100 kg / cm ² and 180 ° C. for 2 minutes, a colorless transparent film having a thickness of 100 μm was obtained. From the transmission electron microscope observation of the obtained film, it was confirmed that the titanium dioxide ultrafine particles having a particle diameter of 3 to 5 nm were uniformly dispersed in the polymer without any aggregation.
Further, it was confirmed by the measurement of thermogravimetric change that the compounding amount of the titanium dioxide ultrafine particles in the film was 10% by weight.

[0023]

Example 2 Titanium dioxide was synthesized in the same manner as in Example 1. The titanium dioxide ultrafine particles were dispersed in 50 ml of octanoic acid and stirred at room temperature for 60 hours. After centrifuging the precipitate,
It was washed three times with ethyl acetate. A portion was taken out, dried at 120 ° C. under reduced pressure for 6 hours, and the infrared spectrum was measured by the KBr tablet method. As a result, a peak of a carboxylate group (—COO ⁻ ) showing the acetic acid modification on the surface of titanium dioxide was measured.
The octanoic acid-modified titanium dioxide ultrafine particles (1 g in a dry state) thus obtained were added to 40 ml of chloroform and sonicated for 1 hour to obtain a uniformly dispersed transparent solution. Chloroform 8 of 9 g of polylactic acid (trade name: LACEA (registered trademark) H-1000 manufactured by Mitsui Chemicals, Inc.)
A solution dissolved in 0 ml was prepared separately, mixed with a solution of titanium dioxide ultrafine particles, and stirred at room temperature for 30 minutes. The solution was further poured into 500 ml of heptane for reprecipitation, and the precipitate was collected by filtration. After precipitate was dried 10 hours at 60 ° C., a pressure of the powder 100kg / cm ^{2, 2} at 180 ° C.
When pressed for a minute, a colorless and transparent film having a thickness of 100 μm was obtained. In addition, as a result of thermogravimetric change measurement, the blending amount of the titanium dioxide ultrafine particles in the film was 10% by weight.
Was confirmed.

[0024]

Comparative Example 1 Ultrafine titanium dioxide particles were synthesized in the same manner as in Example 1. The acetic acid / n-hexylamine modification shown in Example 1 was not carried out, and titanium dioxide was added to 40 ml of chloroform and stirred. However, a transparent solution in which titanium dioxide was uniformly dispersed in chloroform as in Example 1 could not be obtained and was white and turbid. Polylactic acid (trade name: LA
A solution of 9 g of CEA (registered trademark) H-1000 manufactured by Mitsui Chemicals, Inc. in 80 ml of chloroform was prepared separately, mixed with a solution of titanium dioxide ultrafine particles, and stirred at room temperature for 30 minutes. The solution was further poured into 500 ml of heptane for reprecipitation, and the precipitate was collected by filtration. After the precipitate was dried at 60 ° C for 10 hours, the powder was pressed at a pressure of 100 kg / cm2, 180
After pressing at 0 ° C. for 2 minutes, the film was white and opaque. When observed by a transmission electron microscope, submicron-order secondary particles and coarse aggregated particles were observed.

[0025]

[Comparative Example 2] 90% by weight of polylactic acid (LACEA (registered trademark) H-1000: manufactured by Mitsui Chemicals, Inc.) and 10% by weight of titanium dioxide (ST-01 particle size 5 to 7 nm) manufactured by Ishihara Sangyo Co., Ltd. were mixed by a reblender. rear,
Pelletization was performed by a twin-screw extruder at a cylinder set temperature of 180 ° C. The pellets at a pressure of 100 kg / cm2 and 180 ° C for 2
After pressing for a minute, a 100 μm thick film was obtained. The film was white and opaque, and some shades were also seen. When observed by a transmission electron microscope, submicron-order secondary particles and coarse aggregated particles were observed.

[0026]

[Comparative Example 3] 9 g of pellets of polylactic acid (LACEA (registered trademark) H-100: manufactured by Mitsui Chemicals, Inc.) was once dissolved in 80 ml of chloroform, and the solution was poured into 500 ml of heptane to cause reprecipitation and precipitation. The material was collected by filtration. The precipitate was dried at 60 ° C for 10 hours and then at 100 ° C / cm2 pressure and 180 ° C for 2 hours.
After pressing for minutes, a colorless and transparent film having a thickness of 100 μm was obtained.

Regarding the films obtained in Examples and Comparative Examples,
The results of evaluation of haze and photodegradability by the following methods are shown (Table 1). In addition, each evaluation was performed as follows. 1) Appearance and transparency: Excellent: Visual observation can confirm good transparency Poor: Visual observation does not show good transparency 2) Haze: According to JIS K 7105 Was measured to obtain a haze value converted into a thickness of 300 μm. In addition, ΔH
Represents the difference from Comparative Example 3 in which titanium dioxide ultrafine particles were not blended. 3) Photodegradability test: A 2 cm × 5 cm test piece was prepared and a solar simulator (SSS-252161-ER manufactured by Ushio Co., Ltd.) was used to stably perform a test by sunlight.
The sample was irradiated with 00LUX and the change in appearance was examined. 4) Biodegradability test: A sample subjected to a biodegradability test for 1 month was tested for 2 months at a temperature of 35 ° C and a water content of 30%.
After being embedded in the soil, the change in appearance was examined.

[0028]

[Table 1]

EFFECTS OF THE INVENTION In the present invention, titanium dioxide ultrafine particles are compounded with a biodegradable polymer and decomposed and decomposed by light. Further, since the original transparency of the polymer is not impaired, it can be used for molded products such as films requiring transparency.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shoji Obuchi             580-32 Nagaura, Sodegaura-shi, Chiba Mitsui Chemicals, Inc.             Inside the company F-term (reference) 4F071 AA43 AA50 AA54 AB18 AF52                       AH04                 4J002 CF001 CF181 CG001 CL001                       CL021 DE136 FB086 FD206                       GG02

Claims (7)

[Claims] 1. A biodegradable polymer having an acidic group alone on the surface,
Alternatively, a photo-biodegradable polymer composition, characterized in that ultrafine titanium dioxide particles modified with both an acidic group and a basic group are compounded and decomposed and decomposed by light. 2. Tens measured according to JIS K 7105.
2. The light / raw material according to claim 1, wherein the haze (cloudiness value) change (ΔH) of the film containing wt% titanium dioxide is 5% or less in terms of a film thickness of 300 μm with respect to the film containing no titanium dioxide. Degradable polymer composition. 3. An acidic group for modifying the surface of ultrafine titanium dioxide particles is a saturated or unsaturated carboxylic acid, and a basic group is a saturated or unsaturated amine.
2. The photo-biodegradable polymer composition according to 2 above. 4. The photo-biodegradable polymer composition according to claim 1, wherein the biodegradable polymer contains an electron-donating group in a part of its structure. 5. The biodegradable polymer is biodegradable polyester, biodegradable polycarbonate, biodegradable polyamide,
The photo-biodegradable polymer composition according to claim 1, which is one kind or a mixture of two or more kinds selected from biodegradable polyamino acids. 6. The photo-biodegradable polymer composition according to claim 1, wherein the biodegradable polymer is polylactic acid. 7. A molded article using the photo-biodegradable polymer composition according to claim 1.