JP2014234467A - Sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet excellent in heat resistance, transparency, and impact resistance.SOLUTION: The sheet contains a polylactic acid resin and an acrylic block copolymer. The acrylic block copolymer is either a polymer which has a segment comprising methyl methacrylate and a segment comprising an acrylic ester, or a polymer which has a segment comprising methyl methacrylate and a segment comprising a methacrylic ester. The polylactic acid resin has a melting point of 190°C or higher and lower than 230°C.

Description

  An object of this invention is to provide the sheet | seat excellent in heat resistance, transparency, and impact resistance.

  Polylactic acid is a polymer that is melt-moldable with excellent transparency and has biodegradable characteristics, so that it can be decomposed in the natural environment and released as carbon dioxide or water after use. Development has been promoted. On the other hand, in recent years, polylactic acid itself is made from renewable resources (biomass) originating from carbon dioxide and water, so carbon that does not increase or decrease in the global environment even if carbon dioxide is released after use. Neutral properties have attracted attention and are expected to be used as environmentally friendly materials. In addition, lactic acid, which is a monomer of polylactic acid, is being produced at low cost by fermentation using microorganisms, and has been considered as an alternative material for general-purpose polymers made of petroleum-based plastics. As it is put into practical use, it has come to be used as a molded container for food and a cup lid for beverages. However, since polylactic acid has low heat resistance compared to polypropylene and biaxially stretched polystyrene, which are generally used as food containers, it is currently limited to containers that do not require heat resistance. .

  As one means for solving such problems, attention has been paid to the use of a polylactic acid resin forming a stereocomplex. The polylactic acid resin forming the stereocomplex is formed by mixing optically active poly-L-lactic acid and poly-D-lactic acid, and has a very high melting point and crystallization speed compared to ordinary polylactic acid resin. . Since the polylactic acid resin containing a stereocomplex crystal exhibits high rigidity even at high temperatures, it can be expected to develop into a container that requires heat resistance. Polylactic acid resins with stereocomplex crystals are known to show very high transparency despite being crystallized, and are suitable for food containers and other applications where transparency is very important. It can be said that. From such a background, applications relating to a molded body made of a mixture of poly-L-lactic acid and poly-D-lactic acid, such as Patent Document 1 and Patent Document 2, have been filed. However, since polylactic acid resin originally has low impact resistance, there is a problem that it is inferior in practicality when used in the above-described molded container.

JP 2007-90550 A JP 2008-63502 A

  An object of the present invention is to provide a sheet containing a polylactic acid resin excellent in heat resistance, transparency and impact resistance in order to solve the above-described problems.

In order to solve the above problems, the present invention has the following configuration. That is:
(1) A sheet containing a polylactic acid resin and an acrylic block copolymer,
The acrylic block copolymer is a polymer having a segment made of methyl methacrylate and a segment made of acrylic ester, or a polymer having a segment made of methyl methacrylate and a segment made of methacrylate ester,
The polylactic acid resin has a melting point of 190 ° C. or higher and lower than 230 ° C.
(2) The glass transition temperature of the segment made of the acrylic ester is 20 ° C. or less, and the absolute value of the difference in refractive index between the segment and the polylactic acid resin is 0.03 or less, or the segment made of the methacrylate ester The glass transition temperature of the sheet is 20 ° C. or less, and the absolute value of the difference in refractive index between the segment and the polylactic acid resin is 0.03 or less.
(3) The sheet according to (1) or (2), wherein the stereo ratio of the polylactic acid resin is 80% or more and 100% or less.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the sheet | seat containing the polylactic acid resin excellent in heat resistance, transparency, and impact resistance.

The present invention is a sheet comprising a polylactic acid resin and an acrylic block copolymer, and the acrylic block copolymer is a polymer having a segment composed of methyl methacrylate and a segment composed of an acrylic ester, A polymer having a segment composed of methyl acid and a segment composed of methacrylic acid ester, wherein the polylactic acid resin has a melting point of 190 ° C. or higher and 230 ° C. or lower.

The polylactic acid resin used in the present invention means that the lactic acid component is 70 mol% or more and 100 mol% or less in 100 mol% of all monomer components constituting the polylactic acid resin.

  And polylactic acid resin may contain other components other than the lactic acid component (L-lactic acid component or D-lactic acid component) in the range which does not impair the performance of this invention. Examples of other components include polycarboxylic acids, polyhydric alcohols, hydroxycarboxylic acids, lactones, and the like. Specifically, succinic acid, adipic acid, sebacic acid, fumaric acid, terephthalic acid, isophthalic acid, 2, Polyvalent carboxylic acids such as 6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium sulfoisophthalic acid or derivatives thereof, ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, octanediol, Neopentyl glycol, glycerin, trimethylolpropane, pentaerythritol, trimethylolpropane or pentaerythritol added with ethylene oxide or propylene oxide, bisphenol with ethyl Polyhydric alcohols such as aromatic polyhydric alcohols, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol or their derivatives obtained by addition reaction of hydroxide, glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 4-hydroxy Hydroxycarboxylic acids such as valeric acid and 6-hydroxycaproic acid, and glycolide, ε-caprolactone glycolide, ε-caprolactone, β-propiolactone, δ-butyrolactone, β- or γ-butyrolactone, pivalolactone, δ-valerolactone, etc. Lactones and the like.

  Considering the heat resistance of the sheet in the present invention, it is important that the polylactic acid resin of the present invention has a melting point of 190 ° C. or higher and lower than 230 ° C. The melting point of the polylactic acid resin here is a value determined from the raw material of the polylactic acid resin. The melting point of the polylactic acid resin is preferably 200 ° C. or higher and lower than 230 ° C., more preferably 205 ° C. or higher and lower than 230 ° C., and particularly preferably 210 ° C. or higher and lower than 230 ° C.

  In addition, the polylactic acid resin has a melting point of 190 ° C. or higher and lower than 230 ° C., and at the same time, a single crystal derived from poly-L-lactic acid and a single crystal derived from poly-D-lactic acid in the range of 150 ° C. or higher and lower than 185 ° C. In some cases. Then, the melting enthalpy (ΔHsc) of the endothermic curve having a peak at 190 ° C. or more and less than 230 ° C. and the melting enthalpy (ΔHomo) of the endothermic curve having a peak of 150 ° C. or more and less than 185 ° C. are calculated. It is preferable from the viewpoint of transparency that the stereoization rate (Sc rate) is 80% or more and 100% or less. The Sc ratio is more preferably 85% to 100%, particularly preferably 90% to 100%. In addition, from the viewpoint of heat resistance, the polylactic acid resin A in the present invention preferably has a melting enthalpy of a melting peak existing at 190 ° C. or higher and lower than 230 ° C. of 20 J / g or higher.

  As described above, it is important that the polylactic acid resin has a melting point of 190 ° C. or higher and lower than 230 ° C. and an Sc ratio of 80% or more and 100% or less, and a method for controlling the melting point and the Sc ratio within the ranges is not particularly limited. However, as the polylactic acid resin, for example, the following method A) or B) is preferable.

  A) As polylactic acid resin A, a mixture of poly-L-lactic acid and poly-D-lactic acid is used.

  B) As the polylactic acid resin A, a polylactic acid block copolymer composed of a segment composed of poly-L-lactic acid and a segment composed of poly-D-lactic acid is used.

  From the viewpoint of setting the melting point of the polylactic acid resin A to 190 ° C. or higher and lower than 230 ° C., both methods A) and B) are suitable, but the Sc ratio is 80% or more and 100% or less, and the sheet is formed. In particular, it is particularly preferable to use a polylactic acid block copolymer as the method B), that is, the polylactic acid resin A, in that excellent transparency and heat resistance can be obtained.

  Here, poly-L-lactic acid means a polylactic acid resin containing 70 mol% or more and 100 mol% or less of an L-lactic acid component in 100 mol% of all monomer components constituting the polylactic acid resin. Poly-D-lactic acid means a polylactic acid resin containing 70 mol% or more and 100 mol% or less of a D-lactic acid component in 100 mol% of all monomer components constituting the polylactic acid resin. In addition, as poly-L-lactic acid, it is more preferable that the lactic acid component in the polylactic acid resin is 100 mol%, and the L-lactic acid component is more preferably 90 mol% or more and 100 mol% or less, and more preferably 95 mol% or more and 100 mol%. More preferably, it is contained in an amount of not more than mol%, particularly preferably not less than 98 mol% and not more than 100 mol%. Further, as poly-D-lactic acid, it is more preferable that the lactic acid component in the polylactic acid resin is 100 mol%, and further the D-lactic acid component is contained in an amount of 90 mol% to 100 mol%, more preferably 95 mol% or more. The content is more preferably 100 mol% or less, and particularly preferably 98 mol% or more and 100 mol% or less.

  The polylactic acid block copolymer in the present invention refers to a polylactic acid block copolymer composed of a segment composed of poly-L-lactic acid and a segment composed of poly-D-lactic acid. The meanings of poly-L-lactic acid and poly-D-lactic acid here are as described above.

  The weight average molecular weight of the polylactic acid block copolymer when the polylactic acid block copolymer is used as the polylactic acid resin A in the present invention is not particularly limited, but is in the range of 100,000 to 500,000. It is preferable in terms of moldability and mechanical properties. More preferably, it is in the range of 120,000 to 400,000, and more preferably in the range of 130,000 to 350,000.

  As the polylactic acid resin in the present invention, it is preferable to use a polylactic acid block copolymer. In this case, the weight average molecular weight of the segment composed of poly-L-lactic acid and the segment composed of poly-D-lactic acid is particularly limited. Although it is not a thing, among the segment which consists of poly-L-lactic acid in the polylactic acid block copolymer or the segment which consists of poly-D-lactic acid, the weight average molecular weights of any one segment are 60,000 or more and 300,000 or less It is preferable that the weight average molecular weight of the other segment is 10,000 or more and 100,000 or less. More preferably, the segment made of poly-L-lactic acid or the segment made of poly-D-lactic acid in the polylactic acid block copolymer has a weight average molecular weight of 100,000 to 270,000 in one segment, The weight average molecular weight is from 20,000 to 80,000, and particularly preferably, the weight average molecular weight of one segment is from 150,000 to 240,000, and the weight average molecular weight of the other segment is from 30,000 to 60,000.

  In the polylactic acid resin in the present invention, the mass ratio of L-lactic acid units to D-lactic acid units in the whole polylactic acid resin is preferably 80:20 to 20:80, and is 75:25 to 25:75. Is more preferable, and 70:30 to 30:70 is more preferable. When the mass ratio of each of the L-lactic acid unit and the D-lactic acid unit is in the range of 80:20 to 20:80, the polylactic acid resin easily forms a stereocomplex crystal. As a result, the melting point of the polylactic acid resin A Is 190 ° C. or higher and lower than 230 ° C., and the Sc ratio is 80% to 100%.

  When the polylactic acid block copolymer is used in the polylactic acid resin in the present invention, the production method is not particularly limited, and a general production method of polylactic acid can be used. Specifically, poly-L-lactic acid and poly-D-lactic acid are mixed in a twin-screw extruder to produce a mixture, and the mixture is solid-phase polymerized to produce the polylactic acid block copolymer. A ring-opening polymerization of L-lactide or D-lactide of a cyclic dimer formed from a lactic acid component of a raw material in the presence of a catalyst, and further adding lactide which is an optical isomer of the polylactic acid. The lactide method for producing a polylactic acid block copolymer by ring-opening polymerization, and melt-kneading poly-L-lactic acid and poly-D-lactic acid for a long time at a temperature higher than the melting end temperature of the component having the higher melting point A method for producing a polylactic acid block copolymer by transesterifying the segment of the L-lactic acid component and the segment of the D-lactic acid component, and converting the polyfunctional compound into poly-L-lactic acid and poly-D-lactic acid. Mixed By reacting, poly -L- lactic acid and polylactic -D- acid covalently coupled with a polyfunctional compound, and a method for producing a polylactic acid block copolymer. Any method may be used for the production method of the polylactic acid block copolymer, but a step of producing a mixture by mixing poly-L-lactic acid and poly-D-lactic acid in a twin screw extruder, It is obtained by using a method comprising a step of producing the polylactic acid block copolymer by solid-phase polymerization of the mixture, and a step of producing a sheet of the present invention using the polylactic acid block copolymer. The sheet obtained is preferable in that it has excellent heat resistance and transparency.

  In the present invention, the content of the polylactic acid resin is preferably 50% by mass or more and 99.9% by mass or less when the total component of the sheet of the present invention is 100% by mass. If it is less than 50% by mass, it is inferior in plantiness, which is a characteristic of polylactic acid, and if it is more than 99.9%, it is inferior in impact resistance. More preferable content is 70 mass% or more and 99.5 mass% or less, More preferably, it is 80 mass% or more and 99 mass% or less.

  Furthermore, the sheet according to the present invention has a heat resistance at a predetermined temperature, and when the polylactic acid resin is crystallized by performing a heat treatment at a predetermined temperature, the degree of crystallinity of the polylactic acid resin molding is 10% or more. Preferably, it is 13% or more. When the crystallinity of the molded body is less than 10%, severe deformation occurs due to its own weight at high temperature, which is inferior in practicality. Considering that the ratio of the poly-L-lactic acid segment and the poly-D-lactic acid segment is 1: 1 in the stereocomplex crystal, the upper limit of the crystallinity is 50%.

  The sheet in the present invention contains an acrylic block copolymer in the sense of imparting impact resistance. The acrylic block copolymer in the present invention is a polymer having a segment made of methyl methacrylate and a segment made of acrylic ester, or a polymer having a segment made of methyl methacrylate and a segment made of methacrylate. It is important to be.

  In the sheet of the present invention, the glass transition temperature of the segment made of an acrylate ester is 20 ° C. or less, and the absolute value of the difference in refractive index between the segment and the polylactic acid resin is 0.03 or less, or from the methacrylate ester The segment has a glass transition temperature of 20 ° C. or lower, and the absolute value of the difference in refractive index between the segment and the polylactic acid resin is preferably 0.03 or lower. This will be described in detail below.

  Examples of the unit composed of an acrylic ester include esters composed of a compound having acrylic acid and a hydroxyl group, such as an ester composed of acrylic acid and an aliphatic alcohol, and an ester composed of acrylic acid and a polyalkylene glycol having a terminal hydroxyl group. Can be mentioned. Among these, the glass transition temperature is 20 ° C. or less as a segment composed of the above units, and the absolute value of the difference in the refractive index of polylactic acid is 0.03 or less in terms of imparting impact resistance and transparency. Of particular importance. Here, the refractive index and glass transition temperature of the segment made of acrylate ester are the same values as the homopolymer of the acrylate ester, and the refractive index and glass transition temperature of these homopolymers are “POLYMER HANDBOOK THIRD EDITION”. (Wiley-Interscience). Examples of acrylic esters that satisfy the above characteristics include ethyl acrylate (glass transition temperature: −24 ° C., refractive index: 1.4685), butyl acrylate (glass transition temperature: −54 ° C., refractive index 1.463), acrylic 3-methoxypropyl acid (glass transition temperature: -75 ° C., refractive index 1.471) and lauryl acrylate (“Kyoeisha Chemical Co., Ltd.“ Light Acrylate LA ”) Glass transition temperature: −3 ° C., refractive index: 1 4427), ethoxy-diethylene glycol acrylate (“Kyoeisha Chemical Co., Ltd.“ Light Acrylate EC-A ”) Glass transition temperature: −70 ° C., refractive index: 1.4370), methoxy-triethylene glycol acrylate (Kyoeisha Chemical Co., Ltd.) “Light Acrylate MTG-A” Glass transition temperature: −50 ° C., refractive index: 1.4452 2-hydroxyethyl acrylate (Kyoeisha Chemical Co., Ltd. “Light acrylate HOA (N)” Glass transition temperature: −15 ° C., refractive index: 1.448), 2-acryloyloxyethyl-succinic acid (Kyoeisha Chemical Co., Ltd.) “HOA-MS (N)” glass transition temperature: −40 ° C., refractive index: 1.4642), methoxypolyethylene glycol acrylate (“AM-90G” glass transition temperature: −71 ° C., refractive index) : 1.46), and the like.

  In addition, the unit composed of methacrylic acid ester includes an ester composed of a compound having acrylic acid and a hydroxyl group, such as an ester composed of methacrylic acid and an aliphatic alcohol, or an ester composed of acrylic acid and a polyalkylene glycol having a terminal hydroxyl group. Is mentioned.

  Among these, the glass transition temperature is 20 ° C. or less as a segment composed of the above units, and the absolute value of the difference in the refractive index of polylactic acid is 0.03 or less in terms of imparting impact resistance and transparency. Particularly important, the refractive index and glass transition temperature of the segment composed of the above units are the same values as the homopolymer of the methacrylic acid ester, and the refractive index and glass transition temperature of these homopolymers are “POLYMER HANDBOOK THIRD”. EDITION "(Wiley-Interscience). Examples of methacrylic acid satisfying the above characteristics include dodecyl methacrylate (glass transition temperature: -65 ° C., refractive index: 1.474), methacrylic acid, etc. and 2-ethylhexyl methacrylate (Kyoeisha Chemical Co., Ltd. “Light Ester EH” glass Transition temperature: −10 ° C., refractive index: 1.4398), isodecyl methacrylate (“Light Ester ID” manufactured by Kyoeisha Chemical Co., Ltd.) Glass transition temperature: −41 ° C., refractive index: 1.4424), n-lauryl methacrylate ( “Eye ID” manufactured by Kyoeisha Chemical Co., Ltd. Glass transition temperature: −65 ° C., refractive index: 1.4440), methoxypolyethylene glycol methacrylate (“M-90G” manufactured by Shin-Nakamura Chemical Co., Ltd.) glass transition temperature: −69 ° C., refraction Rate: 1.458).

  In the acrylic block copolymer of the present invention, the content of the segment consisting of methyl methacrylate is 20% or more and 80% or less when all components of the acrylic block copolymer are 100% by mass. preferable. If it is less than 30%, the compatibility between the polylactic acid and the acrylic block copolymer is inferior, and a highly transparent sheet cannot be obtained. On the other hand, if it exceeds 80%, a sufficient impact resistance improving effect cannot be obtained.

  In the acrylic block copolymer of the present invention, the weight average molecular weight of the segment composed of methyl methacrylate is preferably 1000 or more and 50000 or less, and more preferably 3000 or more and 40000 or less. In the acrylic block copolymer of the present invention, the weight average molecular weight of the segment made of acrylic acid ester or the segment made of methacrylic acid ester is preferably 5,000 or more and 500,000 or less, more preferably 10,000 or more and 400,000 or less. preferable.

  In the acrylic block copolymer of the present invention, the content of the segment consisting of an acrylate ester or the segment consisting of a methacrylic acid ester is 20% by mass when all the components of the acrylic block copolymer are 100% by mass. The content is preferably 80% by mass or less. If it is less than 30% by mass, a sufficient impact resistance improving effect cannot be obtained, and if it exceeds 80% by mass, the transparency is inferior.

  The acrylic block copolymer in the present invention may have a segment consisting of the above-mentioned methyl methacrylate and a segment consisting of methyl methacrylate or a segment consisting of methyl acrylate. Any block structure of a coalescence or a multi-block copolymer may be taken.

  Furthermore, the weight average molecular weight of the acrylic block copolymer in the present invention is preferably from 50,000 to 700,000, and more preferably from 100,000 to 400,000.

  As an example of an acrylic block copolymer that satisfies the above-mentioned properties, “Kuraty LA2140e”, “Kuraty LA2250”, “Kuraty LA4285” manufactured by Kuraray Co., Ltd. having a block copolymer structure of methyl methacrylate and butyl acrylate. And “Nanostrength MAM” manufactured by Arkema.

In the present invention, the content of the acrylic block copolymer is preferably 0.1% by mass or more and 30% by mass or less when the total components of the sheet of the present invention are 100% by mass. When the amount is less than 0.1% by mass, the impact resistance is inferior. When the amount is more than 30% by mass, the plant degree, which is a characteristic of polylactic acid, is inferior. More preferable content is 0.5 mass% or more and 20 mass% or less, More preferably, it is 1 mass% or more and 10 mass% or less.

The sheet of the present invention, if necessary, other additives as long as the object of the present invention is not impaired, for example, flame retardants, heat stabilizers, crystal nucleating agents, plasticizers, particles, light stabilizers, antioxidants, Appropriate amounts of coloring agents such as anti-coloring agents, ultraviolet absorbers, antistatic agents, plasticizers, tackifiers, organic lubricants such as fatty acid esters and waxes or antifoaming agents such as polysiloxanes, pigments and dyes it can. The sheet of the present invention may contain a resin other than the polylactic acid resin and the acrylic block copolymer.

The sheet of the present invention may be provided with a functional layer on the surface for the purpose of preventing blocking, preventing antistatic, imparting releasability, improving scratch resistance, and the like. Furthermore, in order to impart designability to the sheet of the present invention, a printing layer can be formed on the surface layer according to the purpose.

Although there is no restriction | limiting in particular in the thickness of the sheet | seat of this invention, It is preferable that they are 50 micrometers or more and 2000 micrometers or less, More preferably, it is 100-1500 micrometers, More preferably, it is 200-750 micrometers.

The sheet of the present invention may have a laminated structure with a layer having a structure different from that of the sheet of the present invention.

  The sheet according to the present invention preferably has a haze of 5% or less in order to develop in applications where transparency is important such as food containers. The haze referred to here is a value in consideration of the thickness of the sheet, and is a value converted to a standard of 250 μm. The lower the haze, the better. However, the practical lower limit is 0.1% due to light absorption of the sheet itself and scattering due to surface roughness. The haze of the sheet is more preferably 4% or less, and further preferably 3% or less.

The sheet in the present invention can be formed into a molded body through a production method including a step of preheating the sheet in the present invention (hereinafter referred to as a preheating step) and a step of forming the preheated sheet. The shape of the molded body is not particularly limited as long as it is obtained by the above-described production method, and examples thereof include a rectangular container or a cylindrical container having a polygonal shape on the bottom surface, a tray, a cup, a case, and The thing which has the shape of those cover materials is mentioned. In addition, the shape of the molded product of the present invention is not particularly limited, but it can be used for display bottles of beverage vending machines, and other various packaging products such as blister packs used for display and packaging of products. Various industrial materials, such as a molded object and a surface material, can be mentioned preferably.

Such a manufacturing method as described above is called thermoforming such as vacuum forming method, vacuum / pressure forming method, plug assist forming method, straight forming method, free drawing forming method, plug and ring forming method, skeleton forming method, etc. Various molding methods can be applied. In the various molding methods, the preheating process described above includes an indirect heating method and a hot plate direct heating method. The indirect heating method is a method in which the sheet is preheated by a heating device installed at a position away from the sheet, and the hot plate is heated directly The method is a method in which the sheet is preheated by contacting the sheet and the hot plate, and any method can be preferably used as the preheating step in the method for producing a molded article of the present invention.

Below, the manufacturing method of the sheet | seat of this invention is described.

  The resin composition as a raw material is melt-extruded into an extruder, foreign matter is removed by a wire mesh, and the flow rate is optimized by a gear pump, and then supplied to a manifold die and extruded from the die into a sheet. The sheet is brought into close contact with the casting drum by an air knife or a system such as electrostatic application, and is cooled and solidified to form an unstretched sheet.

  Here, it is preferable to use a wire mesh mesh of 50 to 400 mesh in order to prevent surface roughness due to mixing of foreign matters such as gels and thermally deteriorated materials.

  The sheet of the present invention is preferably produced by a production method including a step of performing a heat treatment at a temperature of 70 ° C. or higher in order to obtain a heat-resistant sheet having a stereocomplex crystal. In order to improve the heat resistance of the sheet, the temperature of the heat treatment step is preferably 70 ° C. or higher and 210 ° C. or lower, more preferably 75 ° C. or lower and 180 ° C. or lower, and further preferably 80 ° C. or higher and 150 ° C. or lower. The time for performing the heat treatment is preferably 5 seconds to 10 minutes and more preferably 5 seconds to 5 minutes in order to cause crystallization to proceed. Although it does not specifically limit as a method to heat-process, The method by a heating oven and the method by a heating roll are preferable. In the method using a heating oven, as a heating method, a method using hot air, a method using a far infrared heater, a method using a combination thereof, or the like can be preferably employed.

Since the sheet of the present invention is excellent in transparency and heat resistance, and also has reduced environmental load, packaging containers, various electronic / electrical equipment, OA equipment, vehicle parts, machine parts, and other agricultural materials It is useful for various uses such as fishery materials, transport containers, play equipment and sundries. Among them, it can be preferably used for applications requiring moldability, transparency, and heat resistance, such as food containers and beverage cup lids.

[Methods for measuring physical properties and methods for evaluating effects]
The physical property measuring method and the effect evaluating method in the present invention are as follows.

1. Using a sheet thickness dial gauge type thickness gauge (JIS B7503 (1997), UPAIGHT DIAL GAUGE (0.001 × 2 mm), No. 25, measuring element 5 mmφ flat type manufactured by PEACOCK), 10 cm in the MD direction and TD direction of the sheet Ten points were measured at intervals, and the average value was taken as the sheet thickness (μm) of the sheet.

2. Tensile modulus measurement Tensile modulus (MPa)
Using TENSILON UCT-100 manufactured by Orientec Corp. equipped with a thermostatic chamber, stress-strain measurement at 80 ° C. was performed, and samples were cut into strips with a length of 150 mm in the vertical direction and a MD direction of 10 mm in width as the vertical direction. In a thermostatic chamber adjusted to 80 ° C., the distance between the initial tensile chucks is 50 mm, the tensile speed is 200 mm / min, and the measurement is performed according to the method specified in JIS K-7127 (1999). Using the first linear portion, the difference in stress between two points on the straight line was divided by the difference in strain between the same two points to calculate the tensile modulus. The measurement was performed 10 times in total, and the average value was adopted. Since this elastic modulus is an index of rigidity at high temperatures, it can be interpreted that the higher the value, the higher the heat resistance.

3. Transparency: Haze value (%)
The haze value of the sheet was measured using a haze meter HGM-2DP type (manufactured by Suga Test Instruments Co., Ltd.). The measurement was performed 5 times per sample, and was obtained from the average value of the 5 measurements.

4). The weight average molecular weight of the molecular weight polylactic acid resin is a standard polymethyl methacrylate conversion value measured by gel permeation chromatography (GPC). GPC measurement was performed using a WATERS differential refractometer WATERS 410 as a detector, a WATERS MODEL 510 as a pump, and a column in which Shodex GPC HFIP-806M and Shodex GPC HFIP-LG were connected in series. The measurement conditions were a flow rate of 0.5 mL / min, hexafluoroisopropanol was used as a solvent, and 0.1 mL of a solution having a sample concentration of 1 mg / mL was injected.

5. Melting point, stereo ratio (Sc ratio)
The melting point of the polylactic acid resin was measured with a differential scanning calorimeter (DSC) manufactured by PerkinElmer. The measurement conditions are 5 mg of the sample, a nitrogen atmosphere, and a heating rate of 20 ° C./min. Here, the melting point refers to the temperature of the peak top in the crystal melting peak.

  The melting point shown here refers to the first measurement (1stRUN), where the temperature was raised from 30 ° C. to 250 ° C. at a rate of temperature increase of 20 ° C./min, then cooled to 30 ° C. at a rate of temperature decrease of 999 ° C./min. (2ndRUN) is a melting point measured when the temperature is raised from 30 ° C. to 250 ° C. at a rate of temperature increase of 20 ° C./min.

  In addition, the Sc ratio of the polylactic acid resin is measured by the melting point measurement method, and the melting enthalpy (ΔHsc) of the endothermic curve having a peak at 190 ° C. or higher and lower than 230 ° C. and the endotherm having a peak at 150 ° C. or higher and lower than 185 ° C. The value calculated from Formula (1) using the melting enthalpy (ΔHomo) of the curve.

Sc rate = 100 × ΔHsc / (ΔHsc + ΔHomo) (1)
6). Glass Transition Temperature The value described in “POLYMER HANDBOOK THIRD EDITION” (Wiley-Interscience) was used as the glass transition temperature of the segment composed of acrylic acid ester or methacrylic acid ester in the acrylic block copolymer. Moreover, about the thing which is not described in the said literature, the homopolymer was created and it measured using the same apparatus as the measuring method of the said melting | fusing point. As the measurement conditions, the sample was 5 mg in a nitrogen atmosphere, and the temperature was increased from −100 ° C. to 200 ° C. at a temperature increase rate of 20 ° C./min in the first measurement (1stRUN), and then the temperature decrease rate was 999 ° C./min to −100 ° C. Then, the temperature was raised from −100 ° C. to 200 ° C. at a temperature rising rate of 20 ° C./min in the second measurement (2ndRUN). Here, the glass transition temperature is lower in the region where the baseline of the DSC curve measured when the temperature is raised from −100 ° C. to 250 ° C. at 2nd RUN changes to the sigmoid type in the endothermic direction. Refers to the intersection of the extension of the baseline and the tangent of the inflection point in the sigmoid.

7). For the refractive index polylactic acid resin, a sheet made of only the polylactic acid resin is prepared in advance, and then the refractive index (Nx, Ny, Nz) in the MD direction, TD direction, and thickness direction of the sheet is set to 25 ° C. by an Atago Abbe refractometer. The average refractive index (N) was calculated by the following formula.
N = (Nx + Ny + Nz) / 3
The refractive index of the segment made of acrylic acid ester or methacrylic acid ester in the acrylic block copolymer was the value described in “POLYMER HANDBOOK THIRD EDITION” (Wiley-Interscience). Moreover, about the thing which is not described in the said literature, the homopolymer was created and it measured using the Abbe refractometer like polylactic acid.

8). Impact resistance: Impact value (N · m / mm)
Using a film impact tester (manufactured by Toyo Seiki Seisakusho), an impact value was measured using a hemispherical impact head having a diameter of 1/2 inch in an atmosphere of a temperature of 23 ° C. and a humidity of 65% RH. A sheet sample was prepared in a size of 100 mm × 100 mm, and the measurement was performed 5 times per sample. Furthermore, the impact value for each time was divided by the thickness of the measurement sample, and the impact value per unit thickness was obtained from the average value of five measurements. The sample thickness was measured with a digital micrometer.

9. Crystallinity (wide-angle X-ray measurement)
With respect to diffraction peaks obtained by a wide-angle X-ray diffraction method (2θ-θ scan method) with an X-ray diffractometer (D8 ADVANCE manufactured by Bruker AXS), 2θ ranges from 10 to 30 with a diffraction curve accompanying an amorphous part as a baseline. The total area (Stotal) is 100%, and the sum (Ssc) of diffraction peak areas around 12 degrees, 21 degrees, and 24 degrees based on the stereocrystal is obtained, and the crystallinity is obtained by equation (2). .

Crystallinity = Total / (Stotal + area of diffraction curve associated with amorphous part) × 100
... (Formula 2)
Measurement conditions X-ray source: CuKα ray output: 40 kV, 40 mA
Slit diameter: DS = SS = 1 degree, RS = 0.6 mm, RSm = 1 mm
Detector: Scintillation counter Measurement range: 5 to 80 degrees Step width (2θ): 0.05 degrees Scan speed: 1 degree / min

The raw materials used in the production examples, examples, and comparative examples of the present invention are as follows. In the production examples, examples, and comparative examples, the following abbreviations may be used.

Polylactic acid resin A: Production Example 1 (polylactic acid block copolymer composed of a segment composed of poly-L-lactic acid and a segment composed of poly-D-lactic acid, weight average molecular weight = 16.6 million, melting point = 213 ° C., (Sc ratio = 88%, refractive index at 25 ° C .: 1.464)
Polylactic acid resin B: Production Example 2 (mixture of poly-L-lactic acid and poly-D-lactic acid Weight average molecular weight = 19.5 thousand, melting point = 211 ° C., Sc ratio = 65%, refractive index at 25 ° C .: 1 .464)
Polylactic acid resin C: Polylactic acid resin dried by a rotary vacuum dryer at 50 ° C. for 8 hours (“Ingeo” 4043D manufactured by Nature Works; D body amount = 4 mol%, melting point = 150 ° C., Sc ratio = 0%: 1 .461)
Acrylic block copolymer A: Production Example 3 (acrylic block copolymer having a segment made of methyl methacrylate and a segment made of methoxypolyethylene glycol methacrylate; glass transition temperature of the segment made of methoxypolyethylene glycol methacrylate = −69 ° C. Refractive index at 25 ° C. of segment made of methoxypolyethylene glycol methacrylate: 1.458, weight average molecular weight of segment made of methyl methacrylate: 9800, weight average molecular weight of block copolymer: 101,000)
Acrylic block copolymer B: Production Example 4 (acrylic block copolymer having a segment made of methyl methacrylate and a segment made of isoamyl acrylate; glass transition temperature of a segment made of isoamyl acrylate = −45 ° C. acrylic acid (Refractive index at 25 ° C. of segment made of isoamyl: 1.4201, weight average molecular weight of segment made of isoamyl acrylate: weight average molecular weight of block copolymer: 80000)
Acrylic block copolymer B: Production Example 4 (acrylic block copolymer having a segment made of methyl methacrylate and a segment made of propyl methacrylate; glass transition temperature of the segment made of propyl methacrylate = 25 ° C. methoxypolyethylene glycol The refractive index at 25 ° C. of the segment made of methacrylate: 1.484, the weight average molecular weight of the segment made of methyl methacrylate: 9800, and the weight average molecular weight of the block copolymer: 101,000)

[Production Example 1] (Production Example of Polylactic Acid Resin A)
In a reaction vessel equipped with a stirrer and a reflux device, 50% by mass of a 90% by mass L-lactic acid aqueous solution was brought to a temperature of 150 ° C., and the reaction was carried out for 3.5 hours while gradually reducing the pressure to distill off water. did. Thereafter, the pressure was changed to normal pressure in a nitrogen atmosphere, 0.02% by mass of tin (II) acetate was added, and a polymerization reaction was performed for 7 hours while gradually reducing the pressure to 13 Pa at 170 ° C. to obtain poly-L-lactic acid. (PLLA1) was obtained. PLLA1 had a weight average molecular weight of 18,000, a melting point of 149 ° C., and a melting end temperature of 163 ° C.

  The obtained PLLA1 was subjected to crystallization treatment at 110 ° C. for 1 hour in a nitrogen atmosphere, followed by solid phase polymerization under a pressure of 60 Pa for 3 hours at 140 ° C., 3 hours at 150 ° C., and 18 hours at 160 ° C., Poly-L-lactic acid (PLLA2) was obtained. PLLA2 had a weight average molecular weight of 203,000 and a melting point of 170 ° C.

  Next, 50 mass% of 90 mass% D-lactic acid aqueous solution is put into a reaction vessel equipped with a stirrer and a reflux apparatus, and the temperature is adjusted to 150 ° C. Reacted for 5 hours. Then, after making atmospheric pressure under nitrogen atmosphere and adding 0.02% by mass of tin (II) acetate, a polymerization reaction was performed for 7 hours while gradually reducing the pressure to 170 Pa at 13 ° C. (PDLA1) was obtained. PDLA1 had a weight average molecular weight of 17,000, a melting point of 148 ° C., and a melting end temperature of 161 ° C.

  The obtained PDLA1 was subjected to a crystallization treatment at 110 ° C. for 1 hour in a nitrogen atmosphere, followed by solid phase polymerization under a pressure of 60 Pa at 140 ° C. for 3 hours, 150 ° C. for 3 hours, and 160 ° C. for 6 hours. Poly-D-lactic acid (PDLA3) was obtained. PDLA2 had a weight average molecular weight of 42,000 and a melting point of 158 ° C.

  PLLA2 and PDLA2 are preliminarily crystallized under a nitrogen atmosphere at a temperature of 110 ° C. for 2 hours, PLLA2 is added from a resin supply port of a TEX30α twin screw extruder (manufactured by Nippon Steel), and PDLA2 is L / D = Added from the side supply port provided in the portion of 30 and melt kneaded. The twin screw extruder is provided with a plasticizing part set at a temperature of 180 ° C. at a part where L / D = 10 from the resin supply port, and a kneading disk is provided at a part where L / D = 30 as a screw capable of applying shear. The structure was such that mixing was possible under the application of shear. Mixing of PLLA2 and PDLA2 was performed at a mixing temperature of 200 ° C. under application of shear. The strand discharged from the die was cooled in a cooling bath and then pelletized with a strand cutter to obtain a pellet-shaped polylactic acid melt-kneaded resin. The obtained polylactic acid melt-kneaded resin was dried in a vacuum dryer at 110 ° C. and a pressure of 13.3 Pa for 2 hours, then subjected to solid phase polymerization at 140 ° C. and a pressure of 13.3 Pa for 4 hours, and then raised to 150 ° C. The mixture was heated for 4 hours, and further heated to 160 ° C. and subjected to solid phase polymerization for 10 hours to obtain a polylactic acid block copolymer. Next, after dry blending 0.5% by mass with respect to 100% by mass of the obtained polylactic acid block copolymer, a catalyst deactivator (manufactured by ADEKA, “ADEKA STAB” AX-71) was set to 240 ° C. , Melt-kneaded with a PCM30 twin screw extruder with two kneading block sections set at a screw speed of 100 rpm, cool the strand discharged from the die in a cooling bath, and then pelletize it with a strand cutter By doing so, a pellet-shaped polylactic acid resin A was obtained.

[Production Example 2] (Production Example of Polylactic Acid Resin B)
In Production 1, PDLA1 was crystallized at 110 ° C. for 1 hour in a nitrogen atmosphere, and then subjected to solid phase polymerization under a pressure of 60 Pa for 3 hours at 140 ° C., 3 hours at 150 ° C., and 18 hours at 160 ° C. Poly-D-lactic acid (PDLA3) was obtained. PDLA5 had a weight average molecular weight of 201,000 and a melting point of 170 ° C. Polylactic acid resin B was obtained by melt-mixing the PDLA3 and PLLA2 in the same manner as in Production Example 1.

[Production Example 3] (Production Example of Acrylic Block Copolymer A)
After a 2-liter three-necked flask was put under a nitrogen atmosphere, 800 ml of toluene, 2.5 ml of N, N, N ′, N ″, N ″ -pentamethyldiethylenetriamine, 0.6 mol / liter of isobutylbis (2,6 -Di-t-butyl-4-methylphenoxy) 34 ml of a toluene solution of aluminum, 3.5 ml of 1.3 mol / liter of sec-butyllithium were added, and 32 ml of methyl methacrylate was further added, followed by reaction at room temperature for 3 hours. I let you. Subsequently, the internal temperature of the polymerization solution was cooled to −20 ° C., and 260 ml of methoxypolyethylene glycol methacrylate (“M-90G” manufactured by Shin-Nakamura Chemical Co., Ltd.) was added dropwise over 7 hours. Subsequently, the reaction solution was warmed to room temperature and stirred for about 5 hours. This reaction solution was poured into a large amount of methanol, and the deposited precipitate was recovered to obtain an acrylic block copolymer A.

[Production Example 4] (Production Example of Acrylic Block Copolymer B)
After a 2-liter three-necked flask was put under a nitrogen atmosphere, 800 ml of toluene, 2.5 ml of N, N, N ′, N ″, N ″ -pentamethyldiethylenetriamine, 0.6 mol / liter of isobutylbis (2,6 -Di-t-butyl-4-methylphenoxy) 34 ml of a toluene solution of aluminum, 3.5 ml of 1.3 mol / liter of sec-butyllithium were added, and 32 ml of methyl methacrylate was further added, followed by reaction at room temperature for 3 hours. I let you. Subsequently, the internal temperature of the polymerization solution was cooled to −20 ° C., and 95 ml of isoamyl acrylate (“Light Acrylate IAA” manufactured by Kyoeisha Chemical Co., Ltd.) was added dropwise over 7 hours. Subsequently, the reaction solution was warmed to room temperature and stirred for about 5 hours. This reaction solution was poured into a large amount of methanol, and the deposited precipitate was recovered to obtain an acrylic block copolymer B.

Example 1
In a vent-type extruder (A), a pellet mixture of 99% by mass of polylactic acid resin A and 1% by mass of “Kuraray LA4285” manufactured by Kuraray Co., Ltd. as an acrylic block copolymer at 230 ° C. Extrusion while melting and kneading while venting the vacuum vent part, filtering the polymer with a 100 mesh wire mesh, supplying to the manifold die, extruding into a sheet form from the T die die with the die temperature set at 230 ° C., and contacting each other The sheet was discharged between a pair of casting drums that were rotated in the direction and cooled to 40 ° C. and a polishing roll, adhered to the casting drum, solidified by cooling, and an unstretched sheet was produced. Then, the sheet was wound up by a winder.

  The obtained sheet was 250 μm. Next, heat treatment was performed in a hot air oven at a heat treatment temperature of 150 ° C. for 180 seconds. Further, the obtained sheet was formed into a molded body by the method described in the section for preparing a molded body in [Method for measuring physical properties and method for evaluating effect].

The characteristic values of the obtained sheet are as shown in Table 1, and were excellent in transparency, heat resistance and impact resistance.

Example 2, Example 3, and Comparative Examples 1-4 obtained the sheet | seat like Example 1 except having changed the composition of the sheet | seat as the table | surface. The physical properties of the obtained sheet are shown in Tables 1 and 2.

  The present invention relates to a sheet excellent in transparency, heat resistance and impact resistance, and can be preferably used for various packaging materials used for foods and various industrial materials.

Claims (3)

A sheet comprising a polylactic acid resin and an acrylic block copolymer,
The acrylic block copolymer is a polymer having a segment made of methyl methacrylate and a segment made of acrylic ester, or a polymer having a segment made of methyl methacrylate and a segment made of methacrylate ester,
The polylactic acid resin has a melting point of 190 ° C. or higher and lower than 230 ° C.   The glass transition temperature of the segment made of the acrylic ester is 20 ° C. or less, and the absolute value of the difference in refractive index between the segment and the polylactic acid resin is 0.03 or less, or the glass transition of the segment made of the methacrylate ester 2. The sheet according to claim 1, wherein the temperature is 20 ° C. or less, and the absolute value of the difference in refractive index between the segment and the polylactic acid resin is 0.03 or less.   The sheet according to claim 1 or 2, wherein the stereo ratio of the polylactic acid resin is 80% or more and 100% or less.