JP2016169293A - Polylactic acid-based resin composition and sheet-like molded body formed of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polylactic acid-based resin composition which can reduce an environmental load, can obtain a molded body excellent in transparency and heat resistance, and is also excellent in moldability; and a molded body formed of the polylactic acid-based resin composition.SOLUTION: A resin composition contains a polylactic acid resin (A), a specific organic amide compound (B), and an adipic acid ester-based plasticizer (C). A polylactic acid-based resin composition contains 0.1-2 pts.mass of an organic amide compound (B) and 0.1-2 pts.mass of an adipic acid ester-based plasticizer (C) with respect to 100 pts.mass of the polylactic acid resin (A), where a ratio of the polylactic acid resin (A) in the resin composition is 80 mass% or more. The total content of the organic amide compound (B) and the adipic acid ester-based plasticizer (C) is 2.5 pts.mass or less with respect to 100 pts.mass of the polylactic acid resin (A). When a content of the organic amide compound (B) is represented by b, and a content of the adipic acid ester-based plasticizer (C) is represented by c, a relationship of 0.3<c/b<1.5 is satisfied.SELECTED DRAWING: None

Description

  The present invention relates to a polylactic acid resin composition that is excellent in transparency and heat resistance by containing a specific plasticizer and a crystal nucleating agent, and a sheet-like molded article obtained from the polylactic acid resin composition. .

  The polylactic acid resin can be applied to a wide range of uses because heat resistance is improved by sufficiently proceeding with crystallization. However, when a polylactic acid resin is used alone, the crystallization rate may generally be slow. For this reason, after melting the polylactic acid resin and completely dissolving the crystals, it is subjected to extrusion molding to produce a sheet. When the sheet is subjected to normal roll cooling, the sheet is thermoformed. In some cases, the crystallization of the polylactic acid resin does not proceed sufficiently during the molding process. As a result, the obtained molded product is thermally deformed when the glass transition temperature of the polylactic acid resin is 57 ° C. or higher, resulting in poor heat resistance.

  Therefore, for the purpose of imparting heat resistance to a molded body made of a sheet obtained from a polylactic acid resin, crystallization is performed by performing heat treatment, performing stretching orientation, or using both heat treatment and stretching orientation. Methods to promote are being studied.

  As a method of performing heat treatment to promote crystallization of polylactic acid resin, a crystal nucleating agent such as talc is added to polylactic acid resin to produce a sheet having a high crystallization speed, and this sheet is heated to a mold. There is known a manufacturing method in which molding is performed in a short time (Patent Document 1). However, in this case, the transparency is inferior, and the transparency of the sheet before molding is low. Moreover, when the molding is performed, if the resin component is a polylactic acid resin alone, the processability is good, but if other biodegradable resins are blended for the purpose of improving impact resistance and the like, the molding cycle is increased. In some cases, the length becomes extremely long (for example, several times longer), and practical workability may not be obtained.

  In addition, a resin composition is obtained by adding a transparent nucleating agent such as aliphatic carboxylic acid amide, aliphatic carboxylate, aliphatic alcohol, and aliphatic carboxylic acid ester to the aliphatic polyester, and is obtained from this resin composition. A method is known in which a sheet is heat-treated during or after molding (Cited document 2). However, in this case, although the sheet before molding is highly transparent, the transparency may decrease due to crystallization after molding. In addition, there is a problem that the crystallization rate at the time of temperature rise is not sufficient and the heat treatment time required for crystallization is long, so that the practicality is inferior.

  Also known is a method for producing a sheet having excellent transparency and heat resistance by adding a polylactic acid copolymer to a polylactic acid resin and crystallizing it by heating for a molding cycle time (Patent Document 3). There is a method for producing a sheet having excellent transparency and heat resistance by adding a crystallization accelerator or an organic crystal nucleating agent to a polylactic acid-based polymer and controlling the size of the crystal to cause crystallization by heat treatment. Known (Patent Document 4). However, in these cases, although the transparency is excellent, the crystallization speed is not sufficient, so that there is a problem that the heat treatment is short and the heat resistance is inferior due to insufficient crystallization.

  As a method of stretching orientation to promote crystallization of polylactic acid resin, a crystallization speed is obtained by adding a transparent agent such as aliphatic carboxylic acid amide to polylactic acid resin and then orienting it by stretching during molding. A method of improving transparency and maintaining transparency after crystallization is known (Patent Document 5). However, in general, the stretch ratio of the molded body varies greatly depending on the part, so it is difficult to improve the heat resistance of the entire molded body in a molded body having a low-magnification part or a molded body with a low overall magnification. There was a case.

JP 2003-253209 A JP 09-278991 A International Publication No. 2007/142106 Pamphlet International Publication No. 2006/121056 Pamphlet JP 2004-345150 A

  The present invention is intended to solve the above-mentioned problems, can reduce the environmental load, can obtain a molded article excellent in transparency and heat resistance, and can also be molded into workability. An object of the present invention is to provide an excellent polylactic acid resin composition. Furthermore, it aims at providing the sheet-like molded object which consists of this polylactic acid-type resin composition, and was excellent in transparency and heat resistance.

As a result of intensive studies to solve the above problems, the present inventors have solved the above problems in a polylactic acid-based resin composition containing a polylactic acid resin, a specific plasticizer, and a specific crystal nucleating agent. The present invention has been found.
That is, the gist of the present invention is as follows.

（２） 有機アミド化合物（Ｂ）とアジピン酸エステル系可塑剤（Ｃ）の合計含有量が、ポリ乳酸樹脂（Ａ）１００質量部に対して、２．５質量部以下であり、かつ有機アミド化合物（Ｂ）の含有量をｂ、アジピン酸エステル系可塑剤（Ｃ）の含有量をｃとしたときに以下の範囲内であることを特徴とする請求項１に記載のポリ乳酸系樹脂組成物。
０．３＜c／ｂ＜１．５
（３） 有機アミド化合物（Ｂ）がエチレンビスステアリン酸アミド、メチレンビスステアリン酸アミド、Ｎ，Ｎ´−ジステアリルアジピン酸アミドから選ばれる少なくとも一種であることを特徴とする、（１）又は（２）に記載のポリ乳酸系樹脂組成物。
（４） （１）〜（３）のいずれかに記載のポリ乳酸系樹脂組成物にて形成されるシート状成形体であって、下記（イ）〜（ハ）を同時に満足することを特徴とするシート状成形体。
（イ）厚みが１００〜５００μｍである。
（ロ）１１０℃、２０秒熱処理後のヘイズ値が１５以下である。
（ハ）（イ）の熱処理後、ＤＳＣで測定した融解熱量が２５Ｊ/ｇ以上である。 (1) A resin composition comprising a polylactic acid resin (A), an organic amide compound (B) represented by the following formula (1) or formula (2), and an adipic ester plasticizer (C): The organic amide compound (B) is contained in an amount of 0.1 to 2 parts by weight (B) and the adipic acid ester plasticizer (C) is contained in an amount of 0.1 to 2 parts by weight with respect to 100 parts by weight of the lactic acid resin (A). A polylactic acid resin composition, wherein the proportion of the polylactic acid resin (A) in the resin composition is 80% by mass or more.

(2) The total content of the organic amide compound (B) and the adipic acid ester plasticizer (C) is 2.5 parts by mass or less with respect to 100 parts by mass of the polylactic acid resin (A), and the organic amide 2. The polylactic acid resin composition according to claim 1, wherein the polylactic acid resin composition is in the following range when the content of the compound (B) is b and the content of the adipic acid ester plasticizer (C) is c. object.
0.3 <c / b <1.5
(3) The organic amide compound (B) is at least one selected from ethylene bis stearic acid amide, methylene bis stearic acid amide, N, N′-distearyl adipic acid amide, (1) or ( The polylactic acid resin composition as described in 2).
(4) A sheet-like molded body formed from the polylactic acid resin composition according to any one of (1) to (3), wherein the following (a) to (c) are satisfied at the same time: A sheet-like molded product.
(A) The thickness is 100 to 500 μm.
(B) The haze value after heat treatment at 110 ° C. for 20 seconds is 15 or less.
(C) After the heat treatment of (i), the heat of fusion measured by DSC is 25 J / g or more.

The polylactic acid-based resin composition of the present invention can be crystallized by heating at a highly practical molding cycle time, and can be molded into various molded products having excellent transparency and heat resistance after crystallization. Can get well. By using the polylactic acid resin composition of the present invention, the range of use of the polylactic acid resin, which is a low environmental load material, can be greatly expanded, and the industrial utility value is extremely high.
Moreover, since the sheet-like molded object of this invention is formed with the polylactic acid-type resin composition of this invention, it is excellent in transparency and heat resistance, and can be widely used for various uses.

Hereinafter, the present invention will be described in detail.
The polylactic acid resin composition of the present invention (hereinafter sometimes simply referred to as “resin composition”) comprises a polylactic acid resin (A), a specific organic amide compound (B), and an adipate ester plasticizer (C ).

As the polylactic acid resin (A), poly (L-lactic acid), poly (D-lactic acid), and a mixture or copolymer thereof can be used.
In the present invention, the polylactic acid resin is preferably crystalline in consideration of the mechanical properties and heat resistance of the obtained molded product, and among them, the melting point is preferably 150 ° C. or higher. If the melting point is less than 150 ° C, the heat resistance may be poor. The melting point of the polylactic acid resin varies depending on the copolymerization ratio of L-lactic acid and D-lactic acid. Among the polylactic acid resins, polylactic acid resins mainly composed of poly (L-lactic acid) have been put into practical use. However, polylactic acid resins mainly composed of poly (L-lactic acid) depend on optical purity. Its melting point is different. In order to set the melting point of the polylactic acid resin to 150 ° C. or higher, the ratio of the D-lactic acid component is preferably 5.0 mol% or less, and the ratio of the D-lactic acid component is 2.0 mol% or less. It is preferable that the ratio of the D-lactic acid component is 1.5 mol% or less. In general, the upper limit of the melting point of the polylactic acid resin is about 190 ° C.

  The amount of residual lactide of the polylactic acid resin (A) is preferably less than 0.5% by mass. If the amount of residual lactide is 0.5% by mass or more, not only may there be an adverse effect on processability such as a large amount of fumes during processing, but hydrolysis of the resulting molded product may be accelerated. .

  The weight average molecular weight (Mw) of the polylactic acid resin (A) is preferably 100,000 to 300,000, more preferably 120,000 to 200,000. If the Mw of the polylactic acid resin is less than 100,000, the melt viscosity is too low, and the resulting molded product tends to be inferior in mechanical properties. On the other hand, when Mw exceeds 300,000, the melt viscosity becomes too high and melt extrusion tends to be difficult when obtaining a molded product. The Mw of the polylactic acid resin can be measured by gel permeation chromatography (GPC) described later.

The polylactic acid resin composition of the present invention may contain other thermoplastic resins other than the polylactic acid resin (A), but the content of the polylactic acid resin (A) in the resin composition is The content of the polylactic acid resin composition is preferably 80% by mass or more, more preferably 90% by mass or more, and further preferably 93% by mass or more.
A commercially available product can be suitably used as the polylactic acid resin (A), and examples thereof include trade names “2500HP”, “3100HP”, “4032D”, “3001D”, “4042D” and the like manufactured by Nature Works.

In the present invention, an organic amide compound represented by the following formula (1) or formula (2) (for the purpose of increasing the crystallization speed of the polylactic acid resin and maintaining transparency when the polylactic acid resin is crystallized) It is necessary to use B) (hereinafter sometimes simply referred to as “organic amide compound (B)”) together with the adipic acid ester plasticizer (C). The organic amide compound (B) is a compound that can exert an effect as a nucleating agent and is excellent in compatibility with a polylactic acid resin. For this reason, when an organic amide compound (B) is used, there exists an advantage that the molded object excellent in transparency can be obtained compared with the case where another crystal nucleating agent is used.

  Moreover, it is preferable that melting | fusing point of an organic amide compound (B) shall be 110-150 degreeC. And it is preferable to select the thing higher than the heat processing temperature at the time of shaping | molding and below the kneading | mixing temperature at the time of obtaining a resin composition. Dispersibility is improved by dissolving the crystal nucleating agent at the time of kneading, and if it is higher than the heat treatment temperature, crystal nucleation is stabilized and the heat treatment temperature is raised, which is preferable from the viewpoint of improving the crystallization speed. Further, those having such a melting point are preferable from the viewpoint of improving transparency and crystallization speed because a large number of fine crystals are rapidly precipitated in the cooling process from the molten state of the resin.

  Specific examples of the organic amide compound (B) include the following compounds. Methylene bis stearic acid amide, ethylene bis capric acid amide, ethylene bis lauric acid amide, ethylene bis stearic acid amide, hexamethylene bis stearic acid amide, N, N'-distearyl adipic acid amide, ethylene bis hydroxy stearic acid amide, hexa Examples include methylene hydroxystearic acid amide and hexamethylene bisoleic acid amide. Among these, methylene bis stearic acid amide, ethylene bis stearic acid amide, and N, N′-distearyl adipic acid amide are preferably used from the viewpoint of easy adjustment of the crystallization rate and transparency. These organic amide compounds (B) may be used alone or in combination.

  The content of the organic amide compound (B) in the polylactic acid-based resin composition of the present invention needs to be 0.1 to 2 parts by mass with respect to 100 parts by mass of the polylactic acid resin (A). It is preferable that it is 0.2-1.5 mass parts, and it is more preferable that it is 0.3-1.2 mass parts. If the amount is less than 0.1 part by mass, the effect as a nucleating agent is poor, and the crystallization rate is insufficient. Therefore, the obtained molded article is inferior in heat resistance. In addition, since the number of crystal nuclei to be generated is reduced, the molded product obtained by increasing the crystal size is inferior in transparency. On the other hand, when the amount exceeds 2 parts by mass, not only the effect as a crystal nucleating agent is saturated, but also the amount of the organic amide compound added is too large, so that the transparency of the polylactic acid-based resin composition is lowered.

  Next, the adipic acid ester plasticizer (C) will be described. The polylactic acid-based resin composition of the present invention contains an adipate ester plasticizer (C) for the purpose of increasing the crystallization speed of the polylactic acid resin and maintaining transparency when the polylactic acid resin is crystallized. It contains. The adipic acid ester plasticizer (C) is a plasticizer excellent in compatibility with the polylactic acid resin. Therefore, when an adipic acid ester plasticizer is used, there is an advantage that a molded body having high crystallization and excellent transparency can be obtained as compared with the case of using other plasticizers.

Examples of the adipate plasticizer (C) include bis [2- (2-methoxyethoxy) ethyl] adipate, bis (butyldiglycol) adipate, benzyl [2- (2-methoxyethoxy) ethyl] adipate, di- Examples include n-butyl adipate, dioctyl adipate, methyl diglycol butyl diglycol adipate, benzyl methyl glycol adipate, benzyl butyl diglycol adipate, and the like.
Among them, from the viewpoint of compatibility with polylactic acid resin and transparency, bis [2- (2-methoxyethoxy) ethyl] adipate, bis (butyldiglycol) adipate, benzyl [2- (2-methoxyethoxy) ethyl] Adipate can be preferably used. These adipate ester plasticizers (C) may be used alone or in combination.

  The content of the adipic acid ester plasticizer (C) in the polylactic acid resin composition of the present invention needs to be 0.1 to 2 parts by mass with respect to 100 parts by mass of the polylactic acid resin (A). Yes, it is preferably 0.2 to 1.5 parts by mass, and more preferably 0.3 to 1.2 parts by mass. If the content is less than 0.1 parts by mass, the effect of promoting crystallization is poor, and crystallization is not sufficiently performed at the time of molding, and the resulting molded product is inferior in heat resistance. On the other hand, when the content exceeds 2 parts by mass, the crystal growth rate becomes faster than the crystal nucleus formation rate, and the crystal size becomes large, so that the transparency is inferior. Moreover, since a glass transition temperature falls when the amount of plasticizer addition increases, the obtained molded object will be inferior to heat resistance or heat-and-moisture resistance. Furthermore, since it becomes easy to bleed out, an external appearance may worsen.

  Even if the organic amide compound (B) or the adipic acid ester plasticizer (C) is added alone to the polylactic acid resin (A), the effect of the present invention cannot be obtained. In general, crystallization of a polymer proceeds in two stages, ie, generation of polymer crystal nuclei and crystal growth. The above-mentioned organic amide compound (B) can be present in the polylactic acid resin (A) with good dispersibility, and upon cooling, a large number of fine crystal nucleating agent crystals are instantly formed, resulting in polymer crystal nuclei. The effect of promoting the formation and increasing the number of crystal nuclei is remarkable. However, even if crystal nuclei are generated, if the crystal growth rate is slow, the total crystallization rate does not reach a satisfactory level. The adipate ester plasticizer (C) has an extremely high effect of improving the crystal growth rate of the polymer. By using the organic amide compound (B) and the adipic ester plasticizer (C) in combination, both the generation of crystal nuclei and the crystal growth can be improved in a balanced manner.

  Furthermore, from the viewpoint of maintaining transparency, a combination of the organic amide compound (B) and the adipic acid ester plasticizer (C) is preferable. In the crystallization of a polymer, if crystal growth is uniformly performed from a large number of polymer crystal nuclei, the polymer is microcrystallized and transparency is increased. Therefore, a combination of an organic amide compound (B) capable of generating a large number of crystal nuclei and an adipate plasticizer (C) having a high effect of improving the crystal growth rate is preferable.

  In order to improve both transparency and heat resistance, it is important to balance the amount of crystal nuclei and the crystal size. For that purpose, an organic amide compound (B) and an adipate plasticizer ( It is important to add C) in a balanced manner.

  That is, when the content of the organic amide compound (B) is b and the content of the adipic ester plasticizer (C) is c, the total content of both is 100 parts by mass of the polylactic acid resin (A). (B + c) is preferably 2.5 parts by mass or less, more preferably 2.0 parts by mass or less, and further preferably 1.5 parts by mass or less.

  Furthermore, the ratio of b and c is preferably 0.3 <c / b <1.5, and more preferably 0.4 <c / b <1.2. When the ratio of b and c is within this range, it is possible to obtain a molded article having a good balance between crystal nucleation and crystal growth and particularly excellent transparency and heat resistance.

  In order to further accelerate the crystallization of the polylactic acid resin (A), the polylactic acid-based resin composition of the present invention has a crystal nucleus other than the organic amide compound (B) as long as the effects of the present invention are not impaired. It is also possible to mix an agent. Examples of such crystal nucleating agents include organic crystal nucleating agents and inorganic crystal nucleating agents. Examples of the organic crystal nucleating agent include phosphonic acid metal salts, sulfonic acid metal salts, and aromatic amides. Examples of the inorganic crystal nucleating agent include layered silicates such as silica, talc, smectite, mica, vermiculite, and swellable fluorine mica.

In the present invention, in order to further promote the crystallization of the polylactic acid resin (A), a crosslinking agent may be used in combination as necessary to crosslink the polylactic acid resin (A).
Examples of the crosslinking agent include (meth) acrylic acid ester compounds, silane compounds, polyhydric anhydrides, epoxy compounds, isocyanate compounds, organic peroxides, metal complexes, and the like. These crosslinking agents can be used alone or in combination of two or more.

  Examples of (meth) acrylic acid ester compounds include glycidyl methacrylate, glycidyl acrylate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, ethylene glycol dimethacrylate, ethylene glycol diacrylate, glycerol dimethacrylate, Examples thereof include hydroxypropyl monomethacrylate, polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, polypropylene glycol dimethacrylate, polypropylene glycol diacrylate, and polytetramethylene glycol dimethacrylate.

  Examples of the silane compound include vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 3-glycidoxypropyltriethoxysilane. Examples of the polyvalent carboxylic anhydride include phthalic anhydride, maleic anhydride, adipic anhydride, trimellitic anhydride, and the like.

  Examples of the epoxy compound include bisphenol A type diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, and terephthalic acid diglycidyl ester. Examples of the isocyanate compound include diisocyanate, triisocyanate, hexamethylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, xylylene diisocyanate, and diphenylmethane diisocyanate.

  Organic peroxides include n-butyl-4,4-bis-t-butylperoxyvalerate, dicumyl peroxide, di-t-butyl peroxide, di-t-hexyl peroxide, 2,5- Dimethyl-2,5-di (t-butylperoxy) hexane, t-butylperoxy-2-ethylhexyl monocarbonate, 3,6,9-triethyl-3,6,9-trimethyl-1,4,7 -Tripa-oxonan and the like. In addition, since an organic peroxide decomposes | disassembles and is consumed at the time of mixing with resin, it may not remain | survive in the obtained polylactic acid-type resin composition. Examples of the metal complex include lithium formate, sodium methoxide, potassium propionate, and magnesium ethoxide.

  The content of the cross-linking agent is preferably 0.01 to 1.0% by mass with respect to the entire polylactic acid resin composition, from the viewpoint of transparency and processability to a molded body. It is more preferable that it is 01-0.5 mass%.

  The polylactic acid resin composition of the present invention may be blended with at least one end-capping agent selected from the group consisting of a carbodiimide compound, an epoxy compound and an oxazoline compound from the viewpoint of improving heat and humidity resistance. The blending amount of the terminal blocking agent is preferably 0.01 to 10% by mass, and preferably 0.1 to 5% by mass with respect to the total amount of the polylactic acid resin composition, from the viewpoint of inhibiting the crystallization rate. It is more preferable.

  The polylactic acid-based resin composition of the present invention includes a pigment, a heat stabilizer, an antioxidant, a vegetable fiber, a reinforcing fiber, a weathering agent, an antistatic agent, an impact resistance agent, and a compatibilizing agent as long as the characteristics are not impaired. Additives such as can be added.

  As a method for obtaining the polylactic acid resin composition of the present invention, a polylactic acid resin (A), an organic amide compound (B), an adipic acid ester plasticizer (C) and, if necessary, by a known method such as melt kneading. There is a method of kneading the additive to be added accordingly. In melt kneading, a general kneader such as a single screw extruder, a twin screw extruder, a roll kneader, or a Brabender can be used, but in order to improve the dispersibility of each component with respect to the polylactic acid resin, It is preferable to use a twin screw extruder.

  As described above, in the method of obtaining a polylactic acid resin composition by melt-kneading, the polylactic acid resin (A) and the organic amide compound (B) may be dry blended and fed from a hopper, or the organic amide You may supply a compound (B) using a feeder etc. from the middle of an extruder. In addition, since the adipic acid ester plasticizer (C) is liquid at room temperature, a method of supplying it from the middle of kneading using a heating quantitative liquid feeder or the like is more preferable. Thereafter, the obtained polylactic acid-based resin composition is taken up in a strand shape and cooled, and then cut into a pellet shape to obtain a pellet of the polylactic acid-based resin composition.

  Next, the molded product of the present invention will be described. The molded article of the present invention is formed from the above-described polylactic acid resin composition of the present invention. Examples of the molded article of the present invention include those obtained by various methods such as injection molding, extrusion molding, blow molding, and foam molding. Once a molded body (sheet-like product) is obtained by extrusion molding, it may be heated again to form a molded body. Alternatively, a molded body (preform) once obtained by injection molding may be blow molded to form a molded body. That is, the final molded body and the molded body (intermediate body) used for obtaining the molded body are included in the molded body of the present invention.

Especially, as a molded object of this invention, the sheet-like molded object made into the sheet form by extrusion molding is preferable. A sheet-like molded object is normally used in order to obtain various molded objects by the shaping | molding method as mentioned later.
The sheet-like molded product of the present invention satisfies the following (A) to (C) simultaneously.
(A) The thickness is 100 to 500 μm.
(B) The haze value after heat treatment at 110 ° C. for 20 seconds is 15 or less.
(C) After the heat treatment of (b), the heat of fusion measured by DSC is 25 J / g or more.

  The thickness of the sheet-like molded product of the present invention is 100 to 500 μm, and preferably 200 to 400 μm. It is preferable to appropriately set the thickness within these ranges depending on the application and required performance.

  The condition (b) is an index indicating that the sheet-like molded product of the present invention maintains transparency even after being subjected to the heat treatment during the molding process. The heat treatment at 110 ° C. for 20 seconds is adopted as a general heat treatment condition during the forming process, and the haze value (Hb) after the heat treatment of the sheet-like formed body of the present invention is 15 or less. Among these, it is preferably 12 or less, and more preferably 10 or less. When the haze value (Hb) exceeds 15, the molded product obtained after the molding process is inferior in transparency.

  And as for the sheet-like molded object of this invention, it is preferable that the heat of fusion measured by DSC is 25 J / g or more after the heat treatment at 110 ° C. for 20 seconds as the condition of (C), especially 30 J / g or more. It is preferable that it is 32 J / g or more. This value indicates the degree of crystallinity after molding and is an index indicating heat resistance. If the heat of fusion is less than 25 J / g, the molded product obtained after the molding process does not have a high degree of crystallinity and is inferior in heat resistance.

  Furthermore, the sheet-like molded product of the present invention has a haze value (Hd) of 20 or less after treating the sheet after the heat treatment (110 ° C., 20 seconds heat treatment) of (b) in a 1700 W, 60 second microwave oven. In particular, it is preferably 18 or less, and more preferably 15 or less. This value is an index of the heat resistance of the molded body obtained after the molding process from the viewpoint of transparency. When the haze value (Hd) after processing in a microwave oven for 1700 w for 60 seconds exceeds 20, a molded product obtained from a sheet-shaped molded product is inferior in transparency when heated in a microwave oven.

  In addition, the difference [(Hd) − (Hb)] between the haze value (Hb) and the haze value (Hd) in (b) is preferably 10 or less, and more preferably 5 or less. If the difference in haze value exceeds 10, the molded product obtained from the sheet-shaped molded product of the present invention is inferior in transparency after being processed in a microwave oven.

  In addition, the measuring method of haze in this invention is performed according to JISK-7105.

  The manufacturing method of the sheet-like molded product of the present invention is not particularly limited, and examples thereof include a T-die method, an inflation method, and a calendar method. Among these, from the viewpoint of versatility, a T-die method in which a material is melt-kneaded and extruded using a T-die is preferable.

  In the case of producing a sheet-like molded article by the T-die method, a polylactic acid resin (A), an organic amide compound (B), an adipate plasticizer (C It is preferable to obtain a resin composition by kneading the resin composition, and supply the pelletized resin composition to a molding machine. Moreover, the method of producing a sheet-like molded object using the masterbatch of an organic amide type compound (B) and an adipic acid ester type plasticizer (C) is also preferable.

  An example of the manufacturing method of the sheet-like molded object of this invention is shown below. For example, the pellets of the polylactic acid resin composition are supplied to a hopper of a single screw extruder or a twin screw extruder, and the twin screw extruder is set, for example, to a cylinder temperature of 180 to 230 ° C and a T die temperature of 200 to 230 ° C. A sheet-like molded body can be obtained by heating, melting and kneading the resin composition pellets, extruding, and cooling with a cast roll set to a temperature range of 30 to 50 ° C.

  The method for obtaining the molded body by molding the sheet-shaped molded body as described above is not particularly limited, but from the viewpoint of versatility, among vacuum forming, pressure forming, vacuum / pressure forming, and press forming. It is preferable to employ any one of these molding methods. Prior to the forming process, it is preferable to heat the sheet-like formed body with a hot plate or hot air. In the hot plate method, since the sheet-shaped molded body and the hot plate are in direct contact, the surface state of the hot plate may be transferred to the sheet-shaped molded body and impair the transparency of the molded body. More preferably, heating is performed.

  A specific example of a method for heating the sheet-like molded body will be described below. First, the sheet-like molded body is heated with a hot plate or hot air for 5 to 60 seconds in a range of (glass transition temperature of polylactic acid resin composition + 20) ° C. to (melting point of polylactic acid resin composition−10) ° C. Then, the sheet-like molded body is softened and, in addition, a part thereof is crystallized. Then, it shape | molds by the method of a vacuum or a compressed air. At this time, if the heating temperature is too low or the heating time is too short, softening is insufficient and shaping cannot be performed. On the other hand, if the heating temperature is too high or the heating time is too long, the crystallization of the sheet-like molded body proceeds too much, and the formability deteriorates.

  The mold temperature during the molding process may be set below the glass transition temperature of the polylactic acid resin composition and released immediately after molding, but the mold temperature is substantially reduced to the polylactic acid resin. It is preferable to crystallize in the mold within the range of 80 to 130 ° C., which is the temperature at which the composition is most easily crystallized, and more preferable to crystallize at 90 to 120 ° C. When the mold temperature exceeds 130 ° C., the crystallization speed of the polylactic acid resin becomes extremely slow, and the crystal may melt because it approaches the melting point of the polylactic acid resin. It may take time to obtain the rigidity required for delay and mold release. On the other hand, when the mold temperature is less than 80 ° C., crystallization is slow, an uncrystallized portion remains, and heat resistance may be insufficient. The time required for molding (molding cycle) is preferably 60 seconds or less, and more preferably 30 seconds or less.

  An example of a molded body obtained from the sheet-like molded body of the present invention obtained by the above method is shown below. For example, various containers such as a sterilization container, a container for pouring hot water, a retort container, a container that can be used in a microwave oven, a lunch box, a hot drink lid, etc. It can be used for trays and the like, and can be suitably used for container lids, blister packs, clear cases and the like that require transparency.

Hereinafter, the present invention will be described more specifically with reference to examples. The measurement methods used for evaluating the examples and comparative examples are as follows.
(1) Weight average molecular weight (Mw) of polylactic acid resin
Using a gel permeation chromatography device (manufactured by Shimadzu Corporation) equipped with a differential refractive index detector (manufactured by Shimadzu Corporation, trade name “RID-10A”), tetrahydrofuran (THF) as an eluent and a flow rate of 1.0 ml / min. , Measured at 40 ° C. As columns, SHODEX KF-805L and KF-804L (manufactured by Showa Denko KK) were used. The sample was dissolved in 0.5 ml of chloroform after dissolving 10 mg of the resin composition, diluted with 5 ml of THF, filtered through a 0.45 μm filter, and then used for measurement. The molecular weight was converted using polystyrene (manufactured by Waters) as a standard sample.
(2) Amount of residual lactide of polylactic acid resin As a sample solution for measurement, 0.5 ml of a sample, 10 ml of dichloromethane, and 0.5 ml of a 100 ppm internal standard solution were added and stirred and dissolved by a shaker (150 rpm × 40 minutes). Cyclohexane was added thereto to precipitate a polymer, which was filtered through a disk filter for HPLC (pore size: 0.45 μm) and measured by gas chromatography. L-lactide manufactured by Tokyo Chemical Industry Co., Ltd. was used as the standard substance, and 2,6-dimethyl-γ-pyrone was used as the internal standard substance.
Gas chromatography (trade name “HP-6890”, manufactured by Hewlett Packard Co., Ltd.) uses helium as a carrier gas at a flow rate of 2.5 ml / min, an oven program is held at 80 ° C. for 1 minute, and 200 ° C. at 20 ° C./minute. The temperature was raised to 0 ° C., and the temperature was raised to 280 ° C. at 30 ° C./min. The column was DB-17 (30 m × 0.25 mm × 0.25 μm) manufactured by J & W, and the detector was a hydrogen flame ion detector (temperature 300 ° C.), and the internal standard method was used for measurement.

(3) D-form content of polylactic acid resin About 0.3 g of the polylactic acid resin (A) or the resin composition is added to 6 mL of 1N potassium hydroxide / methanol solution, sufficiently stirred at 65 ° C., and then 450 μL of sulfuric acid. And stirred at 65 ° C. to decompose polylactic acid. 5 mL of this sample, 3 mL of pure water, and 13 mL of methylene chloride were mixed and shaken. After stationary separation, about 1.5 mL of the lower organic layer was collected, filtered through an HPLC disk filter having a pore size of 0.45 μm, and then subjected to GC measurement using HP-6890 Series GC system manufactured by Hewlett Packard. The ratio (%) of the peak area of D-lactic acid methyl ester in the total peak area of lactate methyl ester was calculated, and this was used as the D-form content (%).

(4) Haze Transparency was evaluated by measuring various haze values in accordance with JIS K-7105 using the measurement samples obtained from each of the obtained sheet-like molded product and container A.
1) Haze value (Hb) in (b) of sheet-like molded product
A sample was cut out from the obtained sheet-like molded body, and after sandwiching it with a polyimide film having a thickness of 25 μm, after pressing for 20 seconds at 0.5 kgf / cm ² · g with a press machine having a mold temperature of 110 ° C., a diameter of 60 mm This was taken out into a circular shape and used as a measurement sample.
2) Haze value (Hd) after range treatment of sheet-like molded product
30 mL of water was placed in a ceramic crucible having a diameter of 55 mm and a capacity of 50 mL, and the measurement sample of 1) was placed therein and processed in a microwave oven at 1700 W for 60 seconds. The sample after the microwave treatment was used as a measurement sample.
3) Haze value of molded body before range treatment The bottom portion of the obtained container A was cut out and used as a sample for haze measurement (7 mg).
4) 100 mL of water is put into a container made of haze value ceramics after the range treatment of the molded body, the obtained container A is covered, and it is processed in a 1700 W microwave oven for 60 seconds. A sample was cut out from the bottom of the sample and used as a measurement sample (7 mg).
(5) Heat of fusion In the measurement of haze in (4), a differential scanning calorimeter (manufactured by Perkin Elmer, DSC device “1”) was used to measure the “haze value in (b) of the sheet-like molded product”. DSC7 ") was used to measure the temperature rise crystallization heat (ΔHc) and heat of crystal fusion (ΔHm) when the sample was heated from 20 ° C to 200 ° C at a rate of temperature rise of 20 ° C / min. The heat of fusion was calculated.
Heat of fusion (J / g) = | ΔHm | − | ΔHc |

(6) Heat resistance of the molded body 100 mL of water was put into a ceramic container, covered with the container A, and treated in a 1700 W microwave oven for 60 seconds. The appearance of the container A after the microwave treatment is visually checked for deformation, ○ that has not been deformed, ○ that has been confirmed to be deformed, and that the container has not been deformed, but the container is not deformed, but is sticky due to bleed out Those in which was confirmed were evaluated in three grades.
Moreover, the volume before and behind the microwave oven process of the container A was measured, and the dimensional change rate was computed by the following formula. The dimensional change rate is preferably 0.5% or less, more preferably 0.4% or less, and further preferably 0.3% or less.
Dimensional change rate (%) = [100 × (volume before microwave processing−volume after microwave processing) / volume after microwave processing)

Moreover, the various raw materials used for the Example and the comparative example are as follows.
Polylactic acid resin (A-1): “4032D” manufactured by Nature Works, Inc. (D-form content: 1.4 mol%, residual lactide content: 0.2 mass%, Mw: 160000)

・ Organic amide compound (B)
(B-1): Ethylene bis stearamide ("J-550S" manufactured by Ito Oil Co., Ltd., melting point 142 ° C)
(B-2): Methylenebisstearic acid amide (Nippon Kasei Co., Ltd. “Bisamide LA”, melting point 142 ° C.)
(B-3): Distearyl adipic acid amide (Nippon Kasei Co., Ltd. “Sripacs ZSA”, melting point 141 ° C.)
(B-4): Hexamethylenebisoleic acid amide (“Sripax ZHO” manufactured by Nippon Kasei Co., Ltd., melting point 110 ° C.)
(B-5): Hexamethylenebishydroxystearic acid amide (“Sripax ZHH” manufactured by Nippon Kasei Co., Ltd., melting point 135 ° C.)
Other organic amide compound (X-1): ethylene bisbehenamide (Nippon Kasei Co., Ltd. “Sripacs B”, melting point 142 ° C.)

・ Adipate plasticizer (C)
(C-1): Benzyl [2- (2-methoxyethoxy) ethyl] adipate ("DAIFACTY-101" manufactured by Daihachi Chemical Co., Ltd.)
Other plasticizer (Y-1): Tributyl acetyl citrate (“ATBC” manufactured by Taoka Chemical Co., Ltd.)

Example 1
100 parts by mass of polylactic acid resin (A-1), 0.6 parts by mass of organic amide compound (B-1), and 0.4 parts by mass of adipic acid ester plasticizer (C-1) It is supplied to a shaft extruder (TEM26SS type manufactured by Toshiba Machine Co., Ltd.), melt kneaded at an extrusion temperature of 190 ° C., a screw rotation speed of 150 rpm, and a discharge rate of 15 kg / h, extruded, processed into pellets, and a polylactic acid resin composition Got. Thereafter, the obtained pellets were vacuum-dried at 60 ° C. for 40 hours.
The dried pellets were melt extruded at an extrusion temperature of 215 ° C. using a single screw extruder with a screw diameter of 90 mm equipped with a T die having a width of 1000 mm, and a sheet having a thickness of 400 μm was cast using a cast roll set at 40 ° C. A molded body was produced.
The obtained sheet-like molded body is supplied to a continuous vacuum / pressure forming machine (FLPD-141-W type manufactured by Asano Laboratories), preheated at a sheet temperature of 100 ° C. for 6 seconds, and then pressed at a mold of 110 ° C. for 20 seconds. The container A (opening inner diameter = 150 mm, bottom inner diameter = 60 mm, container drawing ratio (L / D) = 0.5, bowl type) was molded.

Examples 2-11, Comparative Examples 1-10
A polylactic acid resin composition was obtained in the same manner as in Example 1 except that the amount and type of the organic amide compound (B) and adipic acid ester plasticizer (B) were changed as shown in Table 1. .
And it carried out similarly to Example 1, the sheet-like molded object was obtained, and the container A was obtained from the obtained sheet-like molded object.

  Table 1 shows the characteristic values and evaluation results of the polylactic acid resin compositions, sheet-like molded articles, and containers obtained in Examples 1 to 11 and Comparative Examples 1 to 10.

  As is clear from Table 1, the polylactic acid resin compositions of Examples 1 to 11 were excellent in moldability. And the sheet-like molded object obtained from this resin composition was excellent in transparency also after heat processing, and the heat of fusion after heat processing was high, and it was excellent also in heat resistance. Furthermore, the container obtained by molding the sheet-like molded body was also excellent in transparency and heat resistance, and had a good appearance. In addition, it was kept transparent even after the microwave treatment.

  On the other hand, the polylactic acid resin composition of Comparative Example 1 has an insufficient amount of adipic ester plasticizer (C), so that the crystallization rate is insufficient, and the sheet-like molded product obtained from the resin composition is: The heat of fusion after heat treatment was low and the heat resistance was poor. Further, the container obtained by molding the sheet-like molded body was greatly deformed after the range treatment, and the haze was greatly deteriorated.

  In the polylactic acid resin compositions of Comparative Examples 2, 5, 9, and 10, since the adipate ester plasticizer (C) was too much, the crystal size was too large, and the sheet shape obtained from the resin composition The molded body was inferior in transparency after heat treatment. Furthermore, the container obtained by molding the sheet-like molded body showed bleed-out after the range treatment and was inferior in appearance. In the polylactic acid resin composition of Comparative Example 3, since the amount of the organic amide compound added was too small, the amount of crystal nuclei was insufficient and the crystal size was large. It became inferior to transparency and heat resistance. The polylactic acid resin composition of Comparative Example 4 was inferior in transparency in both the obtained sheet-like molded product and the container because the amount of the organic amide compound added was too large.

  The polylactic acid-based resin composition of Comparative Example 6 uses a plasticizer other than the adipic acid ester-based plasticizer (C), so that the crystallization speed is insufficient, and the obtained sheet-like molded body and container are both transparent. It was inferior to both heat resistance.

The polylactic acid resin compositions of Comparative Examples 7 and 8 were inferior in compatibility with the polylactic acid resin because an organic amide compound other than the organic amide compound (B) defined in the present invention was used. And both the obtained sheet-like molded object and the container were inferior to both transparency and heat resistance.

Claims (4)

A resin composition comprising a polylactic acid resin (A), an organic amide compound (B) represented by the following formula (1) or formula (2), and an adipate ester plasticizer (C): A) 0.1-2 parts by mass (B) of an organic amide compound (B) and 0.1-2 parts by mass of an adipate ester plasticizer (C) with respect to 100 parts by mass, and a resin composition The polylactic acid-type resin composition characterized by the ratio of the polylactic acid resin (A) in it being 80 mass% or more.

The total content of the organic amide compound (B) and the adipic ester plasticizer (C) is 2.5 parts by mass or less with respect to 100 parts by mass of the polylactic acid resin (A), and the organic amide compound (B The polylactic acid-based resin composition according to claim 1, wherein the content is within the following range, where b is the content of) and c is the content of the adipate plasticizer (C).
0.3 <c / b <1.5 The organic amide compound (B) is at least one selected from ethylene bis stearic acid amide, methylene bis stearic acid amide, and N, N'-distearyl adipic acid amide, according to claim 1 or 2. Polylactic acid resin composition. It is a sheet-like molded object formed with the polylactic acid-type resin composition in any one of Claims 1-3, Comprising: The following (I)-(C) is satisfied simultaneously, Sheet-like molding characterized by the above-mentioned body.
(A) The thickness is 100 to 500 μm.
(B) The haze value after heat treatment at 110 ° C. for 20 seconds is 15 or less.
(C) After the heat treatment of (b), the heat of fusion measured by DSC is 25 J / g or more.