JPH1121438A - Biodegradable plastic colored composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject colored composition capable of producing a molding product having excellent pigment dispersion and colored appearance, comprising a polylactic acid and a polylactic acid-aliphatic polyester copolymer, a pigment and a polyhydric alcohol fatty acid ester as a pigment dispersant. SOLUTION: This composition comprises 10-200 pts.wt. of a pigment- dispersant premixture composed of 100 pts.wt. of a polylactic acid or a polylactic acid-aliphatic polyester copolymer of the formula (R and R' are each a 1-18C alkylene; (m) is a positive integer; (n) and (p) are each 0 or a positive integer; (q) is 0 or 1) (preferably one comprising 0-60 wt.% of a polyester structural unit derived from a dicarboxylic acid and a diol based on a lactic acid-derived structural unit and having 20,000-400,000 weight - average molecular weight) as a pigment dispersion retaining medium, a pigment and 1-250 pts.wt., preferably 5-150 pts.wt. based on 100 pts.wt. of the pigment of a polyhydric alcohol fatty acid ester (e.g. hydroxystearic acid triglyceride) as a pigment dispersant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for coloring polylactic acid as a biodegradable plastic or a copolymer of the same with an aliphatic polyester.

[0002]

2. Description of the Related Art Conventionally, pigments and dyes have been used for coloring thermoplastic resins. However, many dyes have drawbacks in color transfer property, light fastness and the like, and pigments are mainly used.

[0003] The pigment is a particulate matter having a particle size of 0.1 to several tens of μm, and a desired colored state is produced by kneading and adding to a molten resin. However, if the pigment particles are aggregated, a good colored state is obtained. However, the appearance of the resin molded product lacks beauty and sometimes impairs the mechanical strength. Therefore, in order to prevent agglomeration of the pigment particles and obtain a good dispersion state, a method of mixing the pigment with an appropriate dispersing medium, a method of processing the mixed material with a machine having an impact force or a grinding force, a method of removing water, A method in which the pigment wetted by the above method is stirred and mixed with an appropriate dispersion medium, and the wet substance of the pigment is replaced with water by a dispersion medium. Generally, the pigment dispersion becomes better as the latter, but as a simple dispersion method, a method of mixing with an appropriate dispersion medium is often used. Dispersion media include metal soaps other than low molecular weight resins and plasticizers, especially metal soaps that are metal salts of higher fatty acids as a dispersant,
It is widely used for general-purpose resins such as olefins, styrenes and acrylics.

[0004] On the other hand, various compositions have been proposed for biodegradable plastics since they have the advantage of facilitating disposal of plastics. In the classification from the manufacturing process, it can be classified into a microorganism production system, a chemically synthesized system and a natural polymer system. Microbial production systems include microorganism-produced polyester copolymers and microbial polysaccharides.Chemical synthesis systems include water-soluble polymers such as polyvinyl alcohol and polyethylene glycol, aliphatic polyesters such as polycaprolactone, and polylactic acid. Natural polymer systems include starch and cellulose derivatives, chitin / chitosan systems and protein systems. In any case, its practical use has been studied.

[0005] Although these resins have been able to maintain sufficient performance even when used for daily plastic products such as films, sheets, bottles, etc., they are inferior in price and processing to conventional general-purpose thermoplastic resins. Absent. Therefore, there are few examples of practical use except for a part, and there are few examples of coloring, and the optimal formulation of pigment dispersion has not been sufficiently elucidated.

[0006]

SUMMARY OF THE INVENTION Polylactic acid or a polylactic acid-aliphatic polyester copolymer, which is a biodegradable plastic of a chemical synthesis system, is a colorless and transparent resin. To obtain, give good hue in coloring, do not affect the transparency of the resin,
It is necessary to use a pigment having good dispersion. If transparency is emphasized, the amount of the pigment used is naturally reduced, and the dispersion must be better. It is desired that the dispersion be excellent even in the case of coloring that does not require transparency. Therefore, it is conceivable that the pigment is well dispersed and kneaded with a resin. However, many steps are required to knead and finely disperse the pigment, which is not economical. It is conceivable to use a pigment dispersant as a method of easily dispersing.However, a metal salt of a higher fatty acid, which is frequently used, impairs the transparency of the resin or an opaque color in which a large amount of pigment is used. Since a large amount of the metal salt is used, bloom (powder blowing) may occur on the surface of the stored resin molded product.

Therefore, there is a need for a dispersant that disperses the pigment well, does not cause undesirable coloring of the resin, does not impair transparency, does not cause bloom, and does not inhibit biodegradability.

[0008]

Means for Solving the Problems The inventors of the present invention have made intensive studies in view of the above situation, and found that polylactic acid or polylactic acid-aliphatic ester copolymer can be obtained by using a polyhydric alcohol fatty acid ester as a pigment dispersant. It has been found that there is little coloration without impairing the transparency and that the pigment dispersibility in the resin is good and there is no bloom in the resin molded product, and the present invention has been completed.

That is, the present invention first provides a polylactic acid or polylactic acid-aliphatic polyester copolymer composition comprising a pigment and a pigment dispersant as essential components, wherein the pigment dispersant is A biodegradable plastic coloring composition comprising a polyhydric alcohol fatty acid ester.

According to a second aspect of the present invention, the pigment dispersant is used in an amount of 5 to 150 parts by weight per 100 parts by weight of the pigment.
A composition as described.

According to a third aspect of the present invention, in the polylactic acid-aliphatic polyester copolymer, the aliphatic polyester is a copolymer of an aliphatic dicarboxylic acid and a polyhydric alcohol, and is used in an amount of 0 to 100 parts by weight of polylactic acid. 2. The composition according to claim 1, wherein the composition is a copolymer obtained at a ratio of about 150 parts by weight.

According to a fourth aspect of the present invention, there is provided the composition according to any one of the first to third aspects, further comprising a chelating agent and / or an acidic phosphate.

According to a fifth aspect of the present invention, there is provided the composition according to any one of the first to fourth aspects, which is a colorant composition.

And so on. Such a composition is usually obtained as a melt-kneaded body, but may be in various forms such as a masterbatch as a colorant composition, a pellet-like compound for molding, or a final molded product.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Typical and best modes of the embodiment of the present invention will be specifically shown in the following examples. Will be described.

The polylactic acid or the copolymer of polylactic acid and the aliphatic polyester according to the present invention is a product represented by the following formula, wherein the structural unit derived from lactic acid is derived from dicarboxylic acid and diol. The polyester unit derived from dicarboxylic acid and diol is 0 to 15% by weight based on 100% by weight of polylactic acid.
0 parts by weight) having a weight average molecular weight of 20,000 to 400,000.

Further, the polymerization catalyst used in the production of these copolymers is deactivated to improve the stability during kneading and molding.
Those containing structural units derived from chelating agents and / or acidic phosphate esters are also added. For details, see
173266. R, R ': alkylene having 1 to 18 carbon atoms m: positive integer n, p: 0 or positive integer q: 0 or 1 (when p = 0, polylactic acid) (where n = q = 0) The method for producing these polymers is not particularly limited, but the method for producing polylactic acid among lactic acid-based polyesters is based on the use of lactide, which is a cyclic dimer of lactic acid, as a catalyst for the ring-opening polymerization. There is a method of performing ring-opening polymerization in the presence. The copolymerization component other than the component derived from lactic acid of the lactic acid-based polyester includes a polyester structure derived from dicarboxylic acid and diol, a structure derived from lactone, a structure derived from glycolic acid, and a structure derived from polyether. Among these, a method for producing a structure derived from a dicarboxylic acid and a diol of a lactic acid-based polyester includes a method of ring-opening lactide, which is a cyclic dimer of lactic acid, to a polyester of a dicarboxylic acid and a diol in the presence of a ring-opening polymerization catalyst. It can be obtained by a method obtained by copolymerization and transesterification, or by a transesterification reaction between a polyester of dicarboxylic acid and diol and polylactic acid.

The polyester of a dicarboxylic acid and a diol can be obtained by a known and common production method by dehydration / deglycol condensation or transesterification. The diol component is
Although not particularly limited, specifically, ethylene glycol,
Propylene glycol, 1,2-butylene glycol,
1,3-butylene glycol, 1,4-butylene glycol, 2,3-butylene glycol, 1,4-pentanediol, 1,5-pentanediol, 2,4-pentanediol, 1,6-hexanediol, octane Diol, neopentyl glycol, cyclohexane dimethanol, xylene glycol, diethylene glycol,
Examples include triethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, dibutanediol, and polytetramethylene glycol.

The dicarboxylic acid component is not particularly limited, but specific examples thereof include succinic acid, methylsuccinic acid, 2-methyladipic acid, methylglutaric acid, adipic acid, azelaic acid, sebacic acid, brassic acid, dodecanedicarboxylic acid, and cyclohexane. Examples thereof include dicarboxylic acid, maleic anhydride, and fumaric acid. Examples of the polymerization catalyst used in the production of the lactic acid-based polyester include, for example, transesterification catalysts, metals such as tin, zinc, lead, titanium, bismuth, zirconium, germanium, and cobalt, and compounds thereof, particularly metal-organic compounds and carbonates. Salts, halides,
Among them, tin octoate, zinc chloride, alkoxytitanium and the like can be mentioned.

However, if the polymerization catalyst remains in the lactic acid-based polyester, the lactic acid structural units in the lactic acid-based polyester are regenerated in the form of lactide at the time of heat molding, and the strength of the lactic acid-based polyester is reduced. /
Alternatively, it is preferable to deactivate the action of the catalyst by adding an acidic phosphoric acid ester.

The amount of the chelating agent and / or the acidic phosphoric acid ester is 0.1 to 100 parts by weight based on 1 part by weight of the catalyst. The chelating agent is not particularly limited. , Disodium ethylenediaminetetraacetate, oxalic acid, phosphoric acid, pyrophosphoric acid, alizarin, acetylacetone, diethylenetriaminepentaacetic acid, triethylenetetraminehexaacetic acid, catechol,
-T-butylcatechol, L (+)-tartaric acid, DL-tartaric acid, glycine, chromotropic acid, benzoylacetone, citric acid, gallic acid, dimethylcaptopropanol, triethanolamine, cyclohexanediaminetetraacetic acid, ditoluoyltartaric acid, dibenzoyltartaric acid Is mentioned.

The acid phosphates refer to acid phosphates, phosphonates, alkylphosphonic acids, and the like, and mixtures thereof. Specific examples of acidic phosphate esters include monomethyl phosphate, dimethyl phosphate, monoethyl phosphate, diethyl phosphate, monopropyl phosphate, dipropyl phosphate, monoisopropyl phosphate, diisopropyl phosphate, monobutyl phosphate, and phosphorus. Dibutyl acid, monopentyl phosphate, dipentyl phosphate, monohexyl phosphate,
Dihexyl phosphate, monooctyl phosphate, dioctyl phosphate, mono-2-ethylhexyl phosphate, di-2-ethylhexyl phosphate, monodecyl phosphate, didecyl phosphate, diisodecyl phosphate, monoundecyl phosphate, diundecyl phosphate, monophosphate monophosphate Dodecyl, monotetradecyl phosphate, ditetradecyl phosphate, monohexadecyl phosphate,
Examples include dihexadecyl phosphate, monooctadecyl phosphate, dioctadecyl phosphate, monophenyl phosphate, diphenyl phosphate, monobenzyl phosphate, dibenzyl phosphate, and the like.

As the pigment used in the present invention, any of conventionally known inorganic pigments, organic pigments and extender pigments can be used. Examples of the pigment according to the present invention include inorganic pigments such as carbon black, titanium oxide, red iron oxide, ultramarine, cobalt aluminate and other calcined pigments, phthalocyanine, perylene, anthraquinone, quinacridone, isoindolinone, and indolinone. Organic pigments such as danthrene-based and azo-based pigments, and extender pigments such as calcium carbonate, barium sulfate, talc, clay, and silica are exemplified.

As the polyhydric alcohol fatty acid ester for the pigment dispersant according to the present invention, any of commonly used esters known in different applications and fields can be used, but it is preferable that the ester be solid at normal temperature. Further, a hydroxyl group may be contained in the structure. Further, those conventionally known as a pigment dispersant for polycarbonate or polyacetal may be used.

Fatty acids include palmitic acid, myristic acid, lauric acid, oleic acid, stearic acid, montanic acid, hydroxystearic acid and the like, and polyhydric alcohols include glycerin, pentaerythritol and sorbitol. .

Examples of such substances include glycerin mono, di, tripalmitate, palmitic acid mono,
Di, tri, tetrapentaerythritol ester, myristic acid mono, di, trisorbitol ester, glycerin mono, di, trimiristat, glycerin mono,
Di, trilaurate, glycerin mono, di, tristearate, fatty acid polyhydric alcohol esters such as montanic acid alcohol ester, hydroxypalmitic acid mono,
Di, triglyceride, hydroxy myristate mono,
Di, triglyceride, hydroxy lauric acid mono,
Di, triglyceride, hydroxystearic acid mono,
And polyhydric alcohol esters of hydroxyl group-containing fatty acids such as di- and triglycerides.

As the polyhydric alcohol fatty acid ester having a hydroxyl group, the polyhydric alcohol ester of a hydroxyl group-containing fatty acid, that is, the carboxyl group of the hydroxyl group-containing fatty acid and the hydroxyl group of the polyhydric alcohol have an ester bond as compared with the polyhydric alcohol ester of a fatty acid. Compounds having a structure linked by are preferred. This indicates that the hydroxyl groups of the hydroxyl group-containing fatty acid contribute more to the pigment dispersibility than the residual hydroxyl groups of the polyhydric alcohol. As the polyhydric alcohol fatty acid ester having a hydroxyl group according to the present invention,
Glycerin esters of hydroxyl group-containing fatty acids are more preferred.

In order to obtain the composition of the present invention, it is preferable that a pigment and a polyhydric alcohol fatty acid ester as a pigment dispersant are appropriately mixed in advance to prepare a pigment premix, and then mixed with a polymer component.

The proportion of the polyhydric alcohol fatty acid ester used in preparing the pigment premix varies greatly depending on the kind of the pigment, but is usually 1 to 250 parts by weight, preferably 5 to 150 parts by weight, per 100 parts by weight of the pigment. Range of parts.

When an organic pigment or carbon black is used, 50 to 150 parts by weight based on 100 parts by weight of the pigment are used.
Parts by weight, when an inorganic pigment or extender other than carbon black is used, 5-1 to 100 parts by weight of the pigment.
It is particularly preferred that the content be in the range of 00 parts by weight.

The pigment premix may be used in any form. For example, a so-called dry color in which a pigment and a pigment dispersant are uniformly mixed in a powder form, or a pigment in a pigment dispersion holding medium together with a pigment dispersant. Can be used as a masterbatch color which is melt-kneaded and dispersed.

In general, the master batch color may be prepared by mixing a pigment with a pigment dispersant in advance and then dispersing the pigment in a pigment dispersion holding medium at a high concentration. At this time, melt kneading, pulverization, and the like can be appropriately performed.

As the pigment dispersion holding medium, it is preferable to use polylactic acid or polylactic acid-aliphatic polyester copolymer as a biodegradable plastic. When preparing the master batch color, the total weight ratio of the pigment and the pigment dispersant to the pigment dispersion holding medium is not particularly limited, but is usually 10 per 100 parts by weight of the pigment dispersion holding medium.
0 to 200 parts by weight.

In the present invention, as the pigment premix,
It is preferable to use it in the form of a dry color because it has a small heat history. The method for obtaining the composition of the present invention is not particularly limited, but preferably the pigment premix is melt-kneaded together with a resin (polymer) component. The conditions for melt kneading are as follows:
Any condition can be used as long as they are uniformly dispersed, but usually 16
It is performed within a range of 0 to 200 ° C.

The composition of the present invention may further contain a long-chain aliphatic monocarboxylic acid monoalcohol ester which is a known and commonly used pigment dispersant. Such long-chain aliphatic monocarboxylic acid monoalcohol esters include, for example, stearyl acetate, isostearyl propionate,
Eicosyl acetate, myristyl caproate, butylcyclohexyl propionate, cetyl alcohol acetate, stearyl butyrate and the like can be mentioned.

The composition of the present invention may further contain conventionally known additives such as stabilizers, lubricants, plasticizers and fillers, if necessary. Since the composition of the present invention is as described above, a high-concentration pigment dispersion is prepared by blending and melting and kneading a pigment at a high content ratio, and then appropriately pelletized, a masterbatch colorant is prepared. It is useful for biodegradable polyester plastics. In order to obtain such a colorant, at the time of preparing the above-mentioned pigment premix, the polylactic acid or the polylactic acid-fatty acid polyester copolymer constituting the composition of the present invention is essentially used as a pigment dispersion holding medium. Can be achieved.

Further, the composition of the present invention is melt-kneaded at a pigment content at a concentration required for ordinary coloring to form a highly dispersed pigment, which is appropriately pelletized to form a colored molded article. It is considered to be useful as a compound.

The composition of the present invention may be a colored molded product obtained by molding a highly dispersed pigment by melt-kneading at a pigment content of a coloring concentration.

[0039]

Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited thereto. All percentages in the examples are on a weight basis.

Examples 1 and 2 and Comparative Examples 1 to 7 Copper phthalocyanine green pigment (CIPigment Green)
7) 100 parts and 100 parts of the pigment dispersant described in Table 1 were mixed with a small mixer to obtain a powdery colorant. Then this colorant 0.
1 part of a polylactic acid-aliphatic polyester copolymer (polyester of ethylene glycol, 1,6-hexanediol and sebacic acid is 25:75 in weight ratio to polylactic acid, M
FR = 9gr / 10min (190 ° C × 2.16Kg), Hase ゛ = 20.7%, 2-ethylhexyl phosphate as catalyst deactivator 0.1% in addition to 100 parts of pellets, and in-line screw injection molding machine (mold clamping force 50t) , With Dalmage screw)
It was injection molded at 180 ° C. to form a square plate of a colored polylactic acid-aliphatic polyester composition (5 × 9 × 2 mm).

After observing the haze (turbidity) of the obtained plate with a haze meter, the dispersion of the pigment was evaluated with a microscope at a magnification of 100 times using a heat melting press at 190 ° C. to form a film of about 20 μm.

The pigment dispersibility was evaluated on a five-point scale. 5: Very good-no coarse particles (large particles having a particle size of 30 µm or more) at all, and almost no coarse particles (medium particles having a particle size of about 10 to 30 µm) 4: Good-no coarse particles, but coarse There are some particles. 3: Normal-There are some coarse particles. 2: Defective-There are many coarse particles and many coarse particles. 1: Extremely poor-Both large particles and large particles are large. % For one week, the surface was observed, and the bloom was evaluated.

[0043]

[Table 1] Melting point (differential thermal analysis) of triglyceride of human peroxystearate = 77 ° C Melting point of monoglyceritic acid of stearic acid (differential thermal analysis) = 68 ° C Aluminum stearate (mixed salt of malmitic acid and myristic acid at 50% or more of stearic acid) Melting point (differential thermal analysis) = 124 ° C Calcium stearate (mixed salt of malmitic acid and myristic acid at 50% or more of stearic acid) Melting point (differential thermal analysis) = 187 ° C Magnesium stearate (mixed salt of palmitic acid and myristic acid at 50% or more of stearic acid) Melting point (Differential thermal analysis) = 114 ° C Zinc stearate (mixed salt of palmitic acid and myristic acid at 50% or more of stearic acid) Melting point (differential thermal analysis) = 126 ° C Lithium stearate (Permitic acid, myristic at 50% or more of stearic acid) (Mixed salt of acid) Melting point (Differential thermal analysis) = 198 ℃ 12-Human peroxocystearate (Differential thermal analysis) = 145 ° C. 12-hydrate Loki system stearic acid Mak Bu Neshiumu melting point (differential thermal analysis) = 195 ° C.

Examples 3, 4 and Comparative Examples 8 to 14 Instead of copper phthalocyanine green, ultramarine blue (CIPigmen
t Blue 29), using the dispersants listed in Table 2 in 100 parts each,
A colored polylactic acid-aliphatic polyester copolymer composition was obtained in the same manner as in Examples 1 and 2, except that 0.5 part was added. Then, evaluation of haze, pigment dispersion, and bloom generation were observed in the same manner.

Table 2 shows the results.

[0046]

[Table 2] The dispersants used are the same as those shown in Table 1.

Example 5 and Comparative Examples 15 to 19 Quinacridone red (CIPigment Violet 1) was used as a pigment.
Using 9) and the dispersants shown in Table 3, powdered colorants mixed in 100 parts each were obtained. The polylactic acid-aliphatic polyester copolymer (ethylene glycol and 1,6
-Polyester of hexanediol and sebacic acid is 5:95 in weight ratio with polylactic acid, MFR = 90gr / 10min (190 ° C
× 2.16 kg), Hase ゛ = 7.1%, phosphoric acid 2- as a catalyst deactivator
0.1 part to 0.1% ethylhexyl).
A colored polylactic acid-aliphatic polyester copolymer composition was obtained in the same manner as in Example 2, and the haze, the evaluation of pigment dispersion, and the occurrence of bloom were observed in the same manner.

Table 3 shows the results.

[0049]

[Table 3] The dispersant used was the same as that shown in Table 1 except for the PE wax.

PE wax: molecular weight (Mn) = 5000 (fine powder), viscosity (CPS: 140 ° C.) = 3000, softening point = 111 ° C.

[0051]

According to the pigment-containing coloring composition of the present invention, the pigment is uniformly and finely dispersed in a polymer component, that is, polylactic acid or a polylactic acid-aliphatic polyester copolymer. This has a particularly remarkable effect that there is little haze and no bloom due to the pigment dispersant.

Accordingly, a molded article comprising the composition of the present invention is:
It becomes a biodegradable plastic product having an excellent colored appearance. In particular, in a molded article having a low pigment content and having transparency, such as a transparent film or a bottle, excellent transparency and uniform coloring can be achieved.

In the case of a composition having a high pigment content, the composition is effective as a colorant for polylactic acid or a polylactic acid-aliphatic polyester copolymer, and provides an excellent colored appearance to a biodegradable plastic product. Useful for

Claims (5)

[Claims] 1. A polylactic acid or polylactic acid-aliphatic polyester copolymer composition comprising a pigment and a pigment dispersant as essential components, wherein a polyhydric alcohol fatty acid ester is used as the pigment dispersant. Degradable plastic coloring composition. 2. A pigment dispersant of 5 parts by weight per 100 parts by weight of pigment.
The composition according to claim 1, wherein the composition is used in an amount of from 150 to 150 parts by weight. 3. The polylactic acid-aliphatic polyester copolymer, wherein the aliphatic polyester is a copolymer of an aliphatic dicarboxylic acid and a polyhydric alcohol, and has a ratio of 0 to 150 parts by weight based on 100 parts by weight of the polylactic acid. 2. The composition according to claim 1, which is a product copolymerized with the above. 4. The composition according to claim 1, further comprising a chelating agent and / or an acid phosphate. 5. The composition according to claim 1, which is a colorant composition.