POLYESTER RESIN COMPOSITION AND POLYESTER RESIN FORMED ARTICLE

Abstract

A polyester resin composition includes: a polylactic acid; a poly(3-hydroxyalkanoate); pentaerythritol; and a silicate. In the polyester resin composition, an amount of the polylactic acid is from 55 to 75 parts by weight, and an amount of the poly(3-hydroxyalkanoate) (B) is from 25 to 45 parts by weight, with respect to 100 parts by weight of a total amount of the polylactic acid and the poly(3-hydroxyalkanoate); an amount of the pentaerythritol is from 0.05 to 20 parts by weight with respect to 100 parts by weight of the total amount of the polylactic acid and the poly(3-hydroxyalkanoate); and an amount of the silicate is from 10 to 40 parts by weight with respect to 100 parts by weight of the total amount of the polylactic acid and the poly(3-hydroxyalkanoate).

Claims

1. A polyester resin composition comprising: a polylactic acid; a poly(3-hydroxyalkanoate); pentaerythritol; and a silicate, wherein: an amount of the polylactic acid is from 55 to 75 parts by weight, and an amount of the poly(3-hydroxyalkanoate) is from 25 to 45 parts by weight, with respect to 100 parts by weight of a total amount of the polylactic acid and the poly(3-hydroxyalkanoate); an amount of the pentaerythritol is from 0.05 to 20 parts by weight with respect to 100 parts by weight of the total amount of the polylactic acid and the poly(3-hydroxyalkanoate); and an amount of the silicate is from 10 to 40 parts by weight with respect to 100 parts by weight of the total amount of the polylactic acid and the poly(3-hydroxyalkanoate).

2. The polyester resin composition according to claim 1, wherein the silicate is at least one selected from the group consisting of talc, mica, kaolinite, montmorillonite, and smectite.

3. The polyester resin composition according to claim 1, wherein the poly(3-hydroxyalkanoate) is at least one selected from the group consisting of poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), and poly(3-hydroxybutyrate-co-4-hydroxybutyrate).

4. A polyester resin formed article produced by melting the polyester resin composition according to claim 1 and then forming the molten polyester resin composition at 25 to 55° C.

5. The polyester resin composition according to claim 2, wherein the poly(3-hydroxyalkanoate) is at least one selected from the group consisting of poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), and poly(3-hydroxybutyrate-co-4-hydroxybutyrate).

6. A method for producing an article, comprising: melt-kneading a polyester resin composition comprising, with respect to 100 parts by weight of a total amount of a polylactic acid and a poly(3-hydroxyalkanoate): 55 to 75 parts by weight of the polylactic acid; 25 to 45 parts by weight of the poly(3-hydroxyalkanoate); 0.05 to 20 parts by weight of pentaerythritol; and 10 to 40 parts of a silicate, and forming the polyester resin composition.

7. The method according to claim 6, wherein the forming is performed at a cooling temperature of 25 to 55° C.

8. The method according to claim 6, wherein the melt-kneading is performed at a resin temperature of 160 to 200° C.

9. The method according to claim 6, the method further comprising drying the resin composition at a temperature of 40 to 80° C. prior to the forming.

Description

EXAMPLES

[0072] Hereinafter, one or more embodiments of the present invention is specifically described with reference to examples, but the technical scope of one or more embodiments of the present invention is not limited by these examples.

[0073] Polylactic acid (A): products indicated below were used. [0074] PLA-1: Ingeo 3251D manufactured by NatureWorks LLC [0075] PLA-2: Ingeo 3260HP manufactured by NatureWorks LLC [0076] PLA-3: Ingeo 4060D manufactured by NatureWorks LLC

[0077] Poly(3-hydroxyalkanoate) (B): production examples and products indicated below were used. P3HA-1: one obtained in Production Example 1 was used.

Production Example 1

[0078] Culture production was performed by using KNK-005 strain (see U.S. Pat. No. 7384766).

[0079] The composition of a seed medium was: 1 w/v % Meat-extract, 1 w/v % Bacto-Tryptone, 0.2 w/v % Yeast-extract, 0.9 w/v % Na.sub.2HPO.sub.4.12H.sub.2O, and 0.15 w/v % KH.sub.2PO.sub.4 (pH 6.8).

[0080] The composition of a preculture medium was: 1.1 w/v % Na.sub.2HPO.sub.4.12H.sub.2O, 0.19 w/v % KH.sub.2PO.sub.4, 1.29 w/v % (NH.sub.4).sub.2SO.sub.4, 0.1 w/v % MgSO.sub.4.7H.sub.2O, and 0.5 v/v % trace metal salt solution (prepared by dissolving, in 0.1 N hydrochloric acid, 1.6 w/v % FeCl.sub.3.6H.sub.2O, 1 w/v % CaCl.sub.2.2H.sub.2O, 0.02 w/v % CoCl.sub.2.6H.sub.2O, 0.016 w/v % CuSO.sub.4.5H.sub.2O, and 0.012 w/v % NiCl.sub.2.6H.sub.2O). Palm oil was added at one time as a carbon source at a concentration of 10 g/L.

[0081] The composition of a P3HA production medium was: 0.385 w/v % Na.sub.2HPO.sub.4.12H.sub.2O, 0.067 w/v % KH.sub.2PO.sub.4, 0.291 w/v % (NH.sub.4).sub.2SO.sub.4, 0.1 w/v % MgSO.sub.4.7H.sub.2O, 0.5 v/v % trace metal salt solution (prepared by dissolving, in 0.1 N hydrochloric acid, 1.6 w/v % FeCl.sub.3.6H.sub.2O, 1 w/v % CaCl.sub.2.2H.sub.2O, 0.02 w/v % CoCl.sub.2.6H.sub.2O, 0.016 w/v % CuSO.sub.4.5H.sub.2O, and 0.012 w/v % NiCl.sub.2.6H.sub.2O), and 0.05 w/v % BIOSPUREX 200K (defoaming agent: manufactured by Cognis Japan Ltd.).

[0082] First, a glycerol stock (50 μl) of KNK-005 strain was inoculated into the seed medium (10 ml) and seed-cultured for 24 hours. Then, the resulting seed culture was inoculated at 1.0 v/v % into a 3-liter jar fermenter (MDL-300 manufactured by B. E. MARUBISHI Co., Ltd.) containing 1.8 L of the preculture medium. Preculture was performed for 28 hours under operation conditions where a culture temperature was 33° C., a stirring speed was 500 rpm, and a ventilation volume was 1.8 L/min while pH was controlled to be in the range of 6.7 to 6.8. The pH control was performed by using a 14% aqueous ammonium hydroxide solution.

[0083] Then, the resulting preculture was inoculated at 1.0 v/v % into a 10-liter jar fermenter (MDS-1000 manufactured by B. E. MARUBISHI Co., Ltd.) containing 6 L of the production medium. Culture was performed under operation conditions where a culture temperature was 28° C., a stirring speed was 400 rpm, and a ventilation volume was 6.0 L/min while pH was controlled to be in the range of 6.7 to 6.8. The pH control was performed by using a 14% aqueous ammonium hydroxide solution. Palm oil was used as a carbon source. The culture was performed for 64 hours. After the completion of the culture, cells were collected by centrifugal separation, washed with methanol, and lyophilized, and the weight of the dried cells was measured.

[0084] One hundred milliliters of chloroform was added to one gram of the obtained dried cells, and the resulting mixture was stirred at room temperature all day and night to extract the P3HA from the cells. The mixture was filtered to remove the cell residue, and then the resulting filtrate was concentrated by an evaporator until its total volume became 30 ml. Thereafter, 90 ml of hexane was gradually added to the filtrate, and the resulting mixture was left for 1 hour in the state of being gently stirred. The mixture was filtered to separate the deposited P3HA, and then the polyester resin was vacuum-dried at 50° C. for 3 hours. In this manner, the P3HA was obtained.

[0085] The 3HH content of the obtained P3HA was measured by gas chromatography in the following manner. In a vessel, 2 ml of a sulfuric acid-methanol mixed liquid (15:85) and 2 ml of chloroform were added to 20 mg of the dried P3HA, and the vessel was tightly sealed. Then, the resulting mixture was heated at 100° C. for 140 minutes to obtain a methyl ester of P3HA degradation product. After cooling, 1.5 g of sodium hydrogen carbonate was added thereto little by little for neutralization, and the resulting mixture was left as it was until generation of carbon dioxide stopped. The mixture was well mixed with 4 ml of diisopropyl ether added thereto, and then centrifuged. Thereafter, the monomer unit composition of the polyester degradation product in a supernatant was analyzed by capillary gas chromatography. The gas chromatography was performed by using GC-17A manufactured by Shimadzu Corporation as a gas chromatograph and NEUTRA BOND-1 (with a column length of 25 m, a column inner diameter of 0.25 mm, and a liquid film thickness of 0.4 μm) manufactured by GL Sciences Inc. as a capillary column. He gas was used as a carrier gas; a column inlet pressure was set to 100 kPa; and a sample was injected in an amount of 1 μl. Temperature conditions were as follows: the temperature was increased from an initial temperature of 100° C. to 200° C. at a rate of 8° C./min, and was further increased from 200° C. to 290° C. at a rate of 30° C./min. As a result of the analysis performed under the above conditions, the P3HA was found to be poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P3HB3HH) as represented by the chemical formula (1). The content of the 3-hydroxyhexanoate (3HH) was 5.6 mol %.

[0086] After the completion of the culture, P3HB3HH was obtained from the culture solution by the method described in International Publication No. WO 2010/067543. The P3HB3HH had a weight-average molecular weight of 600,000 as measured by GPC.

[0087] P3HA-2: one obtained in Production Example 2 was used.

<Production Example 2>

[0088] P3HB3HH, i.e., poly(3-hydroxyalkanoate) raw material, was obtained in the same manner as in Production Example 1, except that KNK-631 strain was used and palm kernel oil was used as a carbon source. The P3HB3HH had a weight-average molecular weight of 650,000, and the 3HH content therein was 11.4 mol %. P3HA-3: one obtained in Production Example 3 was used.

<Production Example 3>

[0089] By using C. necator H16 strain (ATCC17699) as a production strain, P3HB having a weight-average molecular weight of 850,000 was prepared in accordance with International Publication No. WO 09/145164.

[0090] P3HA-4: EM5400F (P3HB4HB) manufactured by Ecomann was used.

[0091] Other materials used in Examples and Comparative Examples are indicated below.

[0092] Pentaerythritol (C): pentaerythritol (Neulizer P manufactured by The Nippon Synthetic Chemical Industry Co., Ltd.)

[0093] Silicate (D): talc (MICRO ACE K-1 manufactured by Nippon Talc Co., Ltd.)

Example 1

[0094] (Production of Polyester Resin Composition)

[0095] PLA-1 as the polylactic acid (A), P3HA-1 as the poly(3-hydroxyalkanoate) (B), the pentaerythritol (C), and talc as the silicate (D) were blended at a blending ratio shown in Table 1 (blending ratios shown in the table presented below are expressed in part(s) by weight) and melt-kneaded by using an intermeshed co-rotation twin screw extruder (TEM-26SS manufactured by TOSHIBA MACHINE CO., LTD.) at a setting temperature of 160 to 180° C. and a screw rotation speed of 100 rpm to obtain a polyester resin composition. At the time, the resin temperature was 188° C. The temperature of the molten resin discharged from a die was directly measured with a type K thermocouple and defined as the resin temperature. The polyester resin composition was extruded through the die to be a strand, and the strand was cut to obtain pellets. The obtained pellets were dehumidified and dried at 80° C. to remove water therefrom.

[0096] (Injection Molding)

[0097] The obtained pellets made of the polyester resin composition were used as a raw material and molded into a bar-shaped test piece complying with ASTM D-648 standard by using an injection molding machine (Si-100IV manufactured by TOYO MACHINERY & METAL CO., LTD.) under the following conditions: the cylinder setting temperature of the molding machine was 160 to 195° C.; and the setting temperature of a mold (molding temperature) was 40° C.

[0098] (Deflection Temperature Under Load)

[0099] The bar-shaped test piece obtained by the injection molding was stored for one month in the atmosphere at a temperature of 23° C. and a humidity of 50%. Thereafter, the test piece was subjected to deflection temperature under load measurement in accordance with the method B of ASTM D-648, and thereby the deflection temperature under load (hereinafter, abbreviated as “DTUL” in some cases) of the test piece was measured. The higher the deflection temperature under load is, the better it is.

[0100] (Burr Evaluation)

[0101] The test piece obtained by the above injection molding was visually observed for burr evaluation. In the burr evaluation, when no burr formation was found, the test piece was evaluated as Good, and when burr formation was found, the test piece was evaluated as Poor.

Examples 2 to 5

[0102] In each of Examples 2 to 5, pellets of a polyester resin composition and a bar-shaped test piece were prepared in the same manner as in Example 1 at a blending ratio shown in Table 1, and the deflection temperature under load measurement and burr evaluation were performed on each test piece. The results are shown in Table 1.

Comparative Examples 1 to 6

[0103] In each of Comparative Examples 1 to 6, pellets of a polyester resin composition and a bar-shaped test piece were prepared in the same manner as in Example 1 at a blending ratio shown in Table 1, and the deflection temperature under load measurement and burr evaluation were performed on each test piece. The results are shown in Table 1.

TABLE-US-00001 TABLE 1 Components and Properties of Injection-Molded Article Comp. Comp. Comp. Comp. Comp. Comp. EX. 1 EX. 2 EX. 3 EX. 4 EX. 5 EX. 1 EX. 2 EX. 3 EX. 4 EX. 5 EX. 6 Main Raw Polylactic acid (A) PLA-1 PLA-2 PLA-2 PLA-2 PLA-1 PLA-2 PLA-1 PLA-1 PLA-1 PLA-1 PLA-1 Materials Poly(3-hydroxyalkanoate) (B) P3HA-1 P3HA-2 P3HA-3 P3HA-4 P3HA-2 — P3HA-1 P3HA-1 P3HA-2 P3HA-1 P3HA-2 Used PLA-1 60 60 60 60 60 80 40 PLA-2 60 70 60 100  P3HA-1 40 40 40 20 P3HA-2 40 40 40 60 Components P3HA-3 30 P3HA-4 40 Pentaerythritol  1   1.5  1   1.5  1  1  1  1 Silicate 30 30 20 30 30 30 30 10 Evaluation DTUL (° C.) 87 91 90 89 85 55 58 60 62 59 73 Burr Good Good Good Good Good Good Good Good Good Good Poor (Components are expressed in units of parts by weight.)

[0104] As shown in Table 1, Comparative Example 1 only contains the polylactic acid. For this reason, Comparative Example 1 exhibits low thermal resistance and a low deflection temperature under load. Comparative Example 2 only contains the polylactic acid and poly(3-hydroxyalkanoate). For this reason, Comparative Example 2 exhibits a low deflection temperature under load. Comparative Example 3 contains no silicate. For this reason, Comparative Example 3 exhibits a low deflection temperature under load. Comparative Example 4 contains no pentaerythritol. For this reason, Comparative Example 4 exhibits a low deflection temperature under load. In Comparative Example 5, the proportion of the polylactic acid is high. For this reason, Comparative Example 5 exhibits a low deflection temperature under load. Comparative Example 6 exhibits burr formation on the test piece since the proportion of the poly(3-hydroxyalkanoate) is high. On the other hand, in Examples 1 to 5, the polylactic acid is mixed with three components, i.e., poly(3-hydroxyalkanoate), pentaerythritol, and silicate. Therefore, each of Examples 1 to 5 exhibits a high deflection temperature under load even with a high proportion of the polylactic acid, and exhibits no burr formation on the test piece.

Example 6

[0105] (Production of Polyester Resin Composition)

[0106] Pellets of a polyester resin composition were prepared in the same manner as in Example 1 at a blending ratio shown in Table 2.

[0107] (Extrusion Forming)

[0108] By using a single screw extruder (Labo Plastmill of the type “20C200” manufactured by Toyo Seiki Seisaku-Sho, Ltd.) to which a T-die having a width of 150 mm and a lip width of 1.5 mm was attached, the prepared pellets made of the polyester resin composition and used as a raw material were extruded under the conditions of a cylinder setting temperature of 160 to 200° C. and a chill roll setting temperature of 50° C., and thereby a sheet with a thickness of 1 mm was obtained. The obtained sheet was subjected to heat sag evaluation. The evaluation result is shown in Table 2.

[0109] (Heat Sag Test)

[0110] The sheet obtained by the above extrusion forming was stored for one month in the atmosphere at a temperature of 23° C. and a humidity of 50%. Thereafter, a strip-shaped test piece having a width of 12.7 mm and a length of 75 mm was punched out of the sheet. The strip-shaped test piece was subjected to a heat sag test complying with JIS K 7195 (except the thickness and length). In the heat sag test, when the deflection of the strip-shaped test piece was not more than 10 mm at a test temperature of 60° C., the test piece was evaluated as Good, and when the deflection of the test piece was more than 10 mm at the test temperature of 60° C., the test piece was evaluated as Poor. The less the deflection of the test piece is, the higher the thermal resistance is.

Comparative Example 7

[0111] Pellets and a sheet of a polyester resin composition were prepared and a heat sag test and evaluation were performed in the same manner as in Example 6 at a blending ratio shown in Table 2. The evaluation result is shown in Table 2.

Comparative Example 8

[0112] Pellets and a sheet of a polyester resin composition were prepared and a heat sag test and evaluation were performed in the same manner as in Example 6 at a blending ratio shown in Table 2. The evaluation result is shown in Table 2.

Comparative Example 9

[0113] Pellets and a sheet of a polyester resin composition were prepared and a heat sag test and evaluation were performed in the same manner as in Example 6 at a blending ratio shown in Table 2. The evaluation result is shown in Table 2.

TABLE-US-00002 TABLE 2 Components and Properties of Injection-Molded Article (Components are expressed in units of parts by weight.) Comparative Comparative Comparative Example 6 Example 7 Example 8 Example 9 Main Raw Polylactic acid (A) PLA-3 PLA-3 PLA-3 PLA-3 Materials Used Poly(3-hydroxyalkanoate) (B) P3HA-1 — — P3HA-1 Components PLA-1 PLA-2 PLA-3 55 100 100 80 P3HA-1 45 20 P3HA-2 P3HA-3 P3HA-4 Pentaerythritol 1 1 1 Silicate 10 30 30 Evaluation Heat sag Good Poor Poor Poor

[0114] As shown in Table 2, Comparative Example 7 only contains the polylactic acid. For this reason, the sheet deflects greatly. Comparative Example 8 contains no poly(3-hydroxyalkanoate). For this reason, the sheet deflects greatly. In Comparative Example 9, the proportion of the poly(3-hydroxyalkanoate) is low. For this reason, the sheet deflects greatly. On the other hand, in Example 6, the polylactic acid is mixed with three components, i.e., poly(3-hydroxyalkanoate), pentaerythritol, and silicate. Therefore, the sheet does not deflect greatly, and has high thermal resistance.

[0115] Although the disclosure has been described with respect to only a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that various other embodiments may be devised without departing from the scope of the present invention. Accordingly, the scope of the invention should be limited only by the attached claims.