JP4463634B2 - Plasticizer for biodegradable resin - Google Patents

Description

  The present invention relates to a biodegradable resin plasticizer and a biodegradable resin composition excellent in flexibility, transparency and bleed resistance.

In recent years, biodegradable resins that are decomposed by microorganisms in a natural environment have attracted attention, and researches on polyesters derived from polylactic acid, aliphatic polyhydric alcohols and aliphatic carboxylic acids have been actively conducted. In particular, polylactic acid is desirable in that it can be produced using renewable plants such as corn and sweet potato as raw materials. From the viewpoint of physical properties, the glass transition point is 60 ° C., the melting point is 170 to 180 ° C., and the heat stability is high. It has the feature that it is excellent in. However, polylactic acid has a defect that its molecular structure is rigid and therefore lacks flexibility. For this reason, various methods of adding a plasticizer to a resin have been proposed as methods for imparting flexibility. For example, Patent Document 1 discloses a method using an acetylated citrate ester such as acetyltri-n-butyl citrate or acetyltriethyl citrate as a plasticizer. Patent Document 2 discloses a method using acetylated monoglyceride as a plasticizer. However, at present, there are few plasticizers that are satisfactory in terms of flexibility, transparency, and bleed resistance required for resin physical properties.
JP-T 9-501456 JP 2000-302956 A

  An object of the present invention is to provide a plasticizer suitable for a biodegradable resin typified by polylactic acid and a biodegradable resin composition excellent in flexibility, transparency, and bleed resistance.

  The present inventors have found that the above problem can be solved by using a specific ester of alkyl glyceryl ether or an ester of an alkylene oxide adduct of alkyl glyceryl ether as a plasticizer.

  That is, the present invention relates to a biodegradable resin plasticizer containing a compound represented by formula (1) (hereinafter referred to as compound (1)), a biodegradable resin, and a biodegradable resin containing this plasticizer. A resin composition is provided.

(Wherein R ¹ represents a linear or branched alkyl group having 1 to 18 carbon atoms, and COR ³ and COR ⁴ each independently represents a linear or branched acyl group having 2 to 18 carbon atoms. , R ² represents an alkylene group having 2 to 3 carbon atoms, and m + n R ^{2 s} may be the same or different, and m and n are numbers representing the average number of added moles of the oxyalkylene group, and 0 ≦ m ≦ 50, 0 ≦ n ≦ 50, and 0 ≦ m + n ≦ 50.)

  The plasticizer of the present invention has good compatibility with the biodegradable resin, and the biodegradable resin composition containing the plasticizer has excellent flexibility and transparency, and even when stored at high temperatures, the plasticizer bleeds. There is no bleed resistance.

[Plasticizer]
The plasticizer of the present invention contains compound (1). In the compound (1), R ¹ is a linear or branched alkyl group having 1 to 18 carbon atoms from the viewpoint of excellent flexibility, transparency and bleed resistance, and is a linear or branched chain having 1 to 14 carbon atoms. Branched alkyl groups are preferred. Preferred R ¹ is methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert-butyl group, n-amyl group, i-amyl group. Group, n-hexyl group, i-hexyl group, n-heptyl group, i-heptyl group, n-octyl group, i-octyl group, 2-ethylhexyl group, n-nonyl group, i-nonyl group, n -Decyl group, i-decyl group, n-undecyl group, i-undecyl group, n-dodecyl group, i-dodecyl group, n-tridecyl group, i-tridecyl group, n-tetradecyl group, i-tetradecyl group can do.

In the compound (1), COR ³ and COR ⁴ are each independently a linear or branched acyl group having 2 to 18 carbon atoms from the viewpoint of excellent flexibility, transparency, and bleed resistance. -14 linear or branched acyl groups are preferred. Preferred examples of the acyl group having 2 to 14 carbon atoms include acetic acid, propionic acid, butyric acid, valeric acid, isovaleric acid, caproic acid, heptanoic acid, caprylic acid, 2-ethylhexanoic acid, nonanoic acid, capric acid, undecanoic acid, Examples include acyl groups derived from lauric acid, tridecanoic acid, and myristic acid. Moreover R ¹ in compound (1), the total number of carbon atoms of R ³ and R ⁴ is preferably 3 to 22, 3 to 14 is more preferable.

In the compound (1), R ² is an alkylene group having 2 to 3 carbon atoms, preferably an ethylene group or a propylene group. m and n are numbers indicating the average number of added moles of the oxyalkylene group, and satisfy 0 ≦ m ≦ 50, 0 ≦ n ≦ 50, and 0 ≦ m + n ≦ 50, and m + n R ² are the same. Or different. If different, each R ² O bond may be random or block. From the viewpoint of flexibility, compatibility, and bleed resistance, R ² is preferably an ethylene group. m and n are preferably 1 ≦ m + n ≦ 50, more preferably 1 ≦ m + n ≦ 20, and particularly preferably 3 ≦ m + n ≦ 20 from the viewpoints of flexibility, compatibility, and bleed resistance. Further, from the viewpoint of heat-resistant volatility during resin molding, 1 ≦ m + n is preferable, and 3 ≦ m + n is more preferable. The plasticizer of the present invention has relatively good biodegradability. From the viewpoint of biodegradability, R ² is preferably an ethylene group, and m and n are preferably m + n ≦ 50, and m + n ≦ 20. Further preferred. From these viewpoints, m and n are preferably 0 ≦ m ≦ 20, 0 ≦ n ≦ 20, and 1 ≦ m + n ≦ 20, particularly 3 ≦ m + n ≦ 20.

The plasticizer used in the present invention can be produced by a known method.
For example, first, according to the method disclosed in Japanese Patent Laid-Open No. 2000-344701, the formula (2)
R ¹ —OH (2)
(In the formula, R ¹ has the above-mentioned meaning.)
The alkyl glyceryl ether (3-alkoxy-1,2-propanediol) represented by the formula (3) is obtained by hydrolyzing the glycidyl ether obtained by reacting the alcohol represented by the formula (1) with α-halohydrin. .

(In the formula, R ¹ has the above-mentioned meaning.)
Next, ethylene oxide and / or propylene oxide is added to the alkyl glyceryl ether represented by the formula (3) at 100 to 180 ° C. under pressure using an alkali metal compound such as NaOH, KOH, Na ₂ OCO ₃ as a catalyst. The resulting alkylene oxide adduct is reacted with an acid anhydride such as acetic anhydride or butyric anhydride in the absence of a catalyst or in the presence of a catalyst, or by dehydration condensation with a carboxylic acid having 2 to 18 carbon atoms. ) Can be obtained.

  In addition to the compound (1), the plasticizer of the present invention can contain an unreacted component in the production of the compound (1), a plasticizer other than the compound (1), and the like.

  Examples of the plasticizer other than the compound (1) include acetylated lauric acid monoglyceride and acetyltri-n-butyl citrate.

  The content of the compound (1) in the plasticizer of the present invention is preferably 50% by weight or more, more preferably 70% by weight or more, further preferably 90%, from the viewpoint of achieving the object of the present invention. % By weight or more.

[Biodegradable resin]
The biodegradable resin used in the present invention has a biodegradability based on JIS K6953 (ISO 14855) “Aerobic and ultimate biodegradability and disintegration test under controlled aerobic compost conditions”. The polyester resin which has is preferable.

  The biodegradable resin used in the present invention is not particularly limited as long as it has a biodegradability capable of being decomposed into a low molecular weight compound with the participation of microorganisms in nature. For example, aliphatic polyesters such as polyhydroxybutyrate, polycaprolactone, polybutylene succinate, polybutylene succinate / adipate, polyethylene succinate, polylactic acid resin, polymalic acid, polyglycolic acid, polydioxanone, poly (2-oxetanone) Aliphatic aliphatic copolyesters such as polybutylene succinate / terephthalate, polybutylene adipate / terephthalate, polytetramethylene adipate / terephthalate; starch, cellulose, chitin, chitosan, gluten, gelatin, casein, soy protein, collagen, keratin, etc. And a mixture of the above natural polymer and the above aliphatic polyester or aliphatic aromatic copolyester.

  Of these, aliphatic polyesters are preferable from the viewpoint of processability, economy, and availability in large quantities, and polylactic acid resins are more preferable from the viewpoint of physical properties. Here, the polylactic acid resin is polylactic acid or a copolymer of lactic acid and hydroxycarboxylic acid. Examples of the hydroxycarboxylic acid include glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, hydroxyheptanoic acid and the like, and glycolic acid and hydroxycaproic acid are preferable. The molecular structure of polylactic acid is preferably composed of 80 to 100 mol% of either L-lactic acid or D-lactic acid and 0 to 20 mol% of each enantiomer. The copolymer of lactic acid and hydroxycarboxylic acid is composed of 85 to 100 mol% of either L-lactic acid or D-lactic acid and 0 to 15 mol% of hydroxycarboxylic acid units. These polylactic acid resins can be obtained by dehydrating polycondensation using L-lactic acid, D-lactic acid and hydroxycarboxylic acid as a raw material by selecting those having the required structure. Preferably, it can be obtained by ring-opening polymerization by selecting a desired structure from lactide, which is a cyclic dimer of lactic acid, glycolide, which is a cyclic dimer of glycolic acid, and caprolactone. Lactide includes L-lactide, which is a cyclic dimer of L-lactic acid, D-lactide, which is a cyclic dimer of D-lactic acid, meso-lactide obtained by cyclic dimerization of D-lactic acid and L-lactic acid, and D- There is DL-lactide, which is a racemic mixture of lactide and L-lactide. Any lactide can be used in the present invention. However, the main raw material is preferably D-lactide or L-lactide.

  Examples of commercially available biodegradable resins include DuPont, trade name Biomax; BASF, trade name Ecoflex; Eastman Chemicals, trade name EsterBio; Showa Polymer Co., Ltd., trade name Bionore; Nippon Synthetic Chemical Industry Co., Ltd., trade name: Matterby; Mitsui Chemicals, Inc., trade name: Lacia; Nippon Shokubai Co., Ltd., trade name: Lunare; Chisso Corporation, trade name: Novon; Cargill Dow Polymers The product name Nature Works etc. is mentioned.

  Among these, a polylactic acid resin (for example, Mitsui Chemicals, Inc., trade name Lacia H-100, H-280, H-400, H-440; Cargill Dow Polymers, trade name Nature Works) is preferable. ), Aliphatic polyesters such as polybutylene succinate (product name Bionore, manufactured by Showa Polymer Co., Ltd.), aliphatic aromatic copolyesters such as poly (butylene succinate / terephthalate) (trade name Bio, manufactured by DuPont) Max).

  From the viewpoint of heat resistance, a crystalline biodegradable resin having a high L-lactic acid purity is preferable, and orientation crystallization is preferably performed by stretching. Examples of the crystalline biodegradable resin include Lacia H-100, H-400, and H-440 manufactured by Mitsui Chemicals.

[Biodegradable resin composition]
The biodegradable resin composition of the present invention contains the plasticizer of the present invention and a biodegradable resin. The content of the plasticizer of the present invention is preferably 1 to 70 parts by weight, more preferably 3 to 50 parts, from the viewpoints of flexibility, transparency, bleed resistance and economy with respect to 100 parts by weight of the biodegradable resin. Part by weight, particularly preferably 5 to 30 parts by weight.

  The content of the biodegradable resin in the biodegradable resin composition of the present invention is preferably 50% by weight or more, more preferably 70% by weight or more from the viewpoint of achieving the object of the present invention.

  The composition of the present invention can contain other components such as a lubricant in addition to the plasticizer. Examples of the lubricant include hydrocarbon waxes such as polyethylene wax, fatty acids such as stearic acid, fatty acid esters such as glycerol ester, metal soaps such as calcium stearate, ester waxes such as montanic acid wax, and alkylbenzene sulfone. And anionic surfactants having an aromatic ring such as acid salts and anionic surfactants having an alkylene oxide addition moiety such as polyoxyethylene alkyl ether sulfate. The content of these lubricants is preferably 0.05 to 3 parts by weight, more preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of the biodegradable resin.

  The composition of the present invention includes an antistatic agent, an antifogging agent, a light stabilizer, an ultraviolet absorber, a pigment, an inorganic filler, an antifungal agent, an antibacterial agent, a foaming agent, a flame retardant, Plasticizers other than the plasticizer of the present invention can be contained as long as the object of the present invention is not hindered.

  Since the composition of the present invention has good processability and can be processed at a low temperature such as 160 to 190 ° C., it can be calendered and the plasticizer is hardly decomposed. The composition of the present invention can be formed into a film or sheet and used for various applications.

Synthesis Example 1: Synthesis of POE (3) pentyl glyceryl ether diacetate In a 10 L autoclave, pentyl glyceryl ether (3-pentyloxy-1,2-propanediol) (pentyl group is a mixture of linear and branched) 3 kg (18. 5 mol), 10.4 g (0.185 mol) of KOH, nitrogen substitution was performed, the temperature was raised to 110 ° C., dehydration was performed at 5.3 kPa for 1 hour, and then 2444 g of ethylene oxide at 150 ° C. and 0.3 MPa ( 55.5 mol) was added. After aging for 0.5 hours, the reaction mixture was transferred to a flask, 83 g of adsorbent Kyoward 600S (manufactured by Kyowa Chemical Industry Co., Ltd.) was added, and the mixture was stirred at 80 ° C. for 1 hour, filtered under reduced pressure, and POE (3) Pentyl glyceryl ether was obtained. 200 g (0.635 mol) of this product was charged into a 1 L four-necked flask, and 195 g (1.91 mol) of acetic anhydride was added dropwise at 110 to 120 ° C. over 1 hour. After heating at 120 ° C. for 2 hours, acetic acid and acetic anhydride were removed by vacuum distillation, and further vacuum steaming was performed to obtain the target acetate (hereinafter referred to as plasticizer 1). The plasticizer 1 had an acid value of 0.4 (KOHmg / g) and a hydroxyl value of 1 (KOHmg / g) or less.

Synthesis Example 2: Synthesis of POE (6) 2-ethylhexyl glyceryl ether diacetate As in Synthesis Example 1, except that pentyl glyceryl ether is changed to 2-ethylhexyl glyceryl ether and the number of moles of ethylene oxide added is changed from 3 to 6 mol. The target acetate (hereinafter referred to as plasticizer 2) was obtained. The acid value of the plasticizer 2 was 0.3 (KOHmg / g), and the hydroxyl value was 1 (KOHmg / g) or less.

Synthesis Example 3: Synthesis of 2-ethylhexyl glyceryl ether diacetate Except that 200 g of ethylene oxide adduct of pentyl glyceryl ether was changed to 150 g (0.734 mol) of 2-ethylhexyl glyceryl ether and 195 g of acetic anhydride was changed to 225 g (2.2 mol). The target acetate (hereinafter referred to as plasticizer 3) was obtained in the same manner as in Synthesis Example 1. The acid value of the plasticizer 3 was 0.6 (KOHmg / g), and the hydroxyl value was 1 (KOHmg / g) or less.

Examples 1-3 and Comparative Examples 1-2
As a biodegradable resin, a composition comprising 100 parts by weight of a polylactic acid resin (LACEA H-280 manufactured by Mitsui Chemicals, Inc.), which was vacuum-dried at 50 ° C. for 24 hours, and 20 parts by weight of a plasticizer shown in Table 1. The mixture was kneaded with a 4-inch roll at 130 ° C. for 15 minutes, and a test piece having a thickness of 0.5 mm was prepared with a press molding machine at 160 ° C.

  The obtained test pieces were evaluated for flexibility, transparency and bleed resistance by the following methods. These results are shown in Table 1.

<Flexibility evaluation method>
The test piece was punched out with a No. 3 dumbbell, left in a constant temperature room at a temperature of 23 ° C., and a humidity of 50% RH for 24 hours.

<Transparency evaluation method>
The haze value of the test piece was measured using an integrating sphere light transmittance measuring device (haze meter) defined in JIS-K7105. Smaller numbers indicate better transparency.

<Bleed resistance (with or without bleed)>
The test piece (length 100 mm × width 100 mm × thickness 0.5 mm) was stored in a thermostatic bath at 60 ° C. for 60 hours, and the presence or absence of a plasticizer bleed on the surface was observed with the naked eye.

* 1: Acetyl tri-n-butyl citrate
* 2: Acetylated lauric acid monoglyceride

Claims (3)

The biodegradable resin for plasticizer containing a compound represented by the formula (1).

(Wherein R ¹ represents a linear or branched alkyl group having 1 to 8 carbon atoms, COR ³ and COR ⁴ each independently represents an acyl group having 2 carbon atoms, and R ² represents 2 to 2 carbon atoms. 3 represents an alkylene group, and m + n R ^{2 s} may be the same or different, and m and n are numbers indicating the average number of added moles of the oxyalkylene group and satisfying 0 ≦ m + n ≦ 3 . ) A biodegradable resin, biodegradable resin composition containing 1 Symbol placement plasticizer claims (1-50 parts by weight per 100 parts by weight of the biodegradable resin). The biodegradable resin composition according to claim 2 , wherein the biodegradable resin is polylactic acid.