JP2013129719A - Resin composition and molded body obtained by molding the resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin composition containing a polylactic acid resin and excellent in heat resistance and transparency.SOLUTION: The resin composition contains 20-35 mass% of a polylactic acid resin (A) and 65-80 mass% of a methacrylic resin (B), wherein the total content of components other than the polylactic acid resin (A) and the methacrylic resin (B) is ≤10 mass%. A methyl acrylate segment represented by CH-CHCOOCHis not substantially contained in the resin composition.

Description

  The present invention relates to a resin composition mainly composed of a polylactic acid resin and a methacrylic resin, and a molded body formed by molding the resin composition.

  In general, resins such as polypropylene (PP), ABS (acrylonitrile-butadiene-styrene resin), polyamide (PA6, PA66), polyester (PET, PBT), and polycarbonate (PC) are used as molding materials. Molded bodies made from such resins are excellent in moldability and mechanical strength, but when discarded, they increase the amount of dust and are hardly decomposed in the natural environment. However, since it remains in the ground semipermanently, there is a problem that the global environmental load is high.

  On the other hand, in recent years, biodegradable polyester resins such as polylactic acid have attracted attention from the viewpoint of environmental conservation. Among the biodegradable polyester resins, polylactic acid resin, polyethylene succinate, polybutylene succinate, and the like can be mass-produced, and thus are low in cost and highly useful.

  Among them, polylactic acid resin can be produced from plants as raw materials, and even if incinerated after use, it is neutral as a carbon balance considering carbon dioxide absorbed during the growth of these plants. That is, the polylactic acid resin is a resin having a low load on the global environment.

  However, the polylactic acid resin itself is inferior to various conventionally used molding resins (that is, polypropylene, polyamide, etc.) in terms of moldability and various physical properties. Therefore, in order to achieve a good balance between low environmental impact, moldability, and physical properties in the polylactic acid resin, it contains various additives, modifies the polylactic acid resin itself, and other resins than the polylactic acid resin. A method of mixing (alloying) is being studied.

  For example, Patent Literature 1 describes that an impact resistance improving material is added to a polylactic acid resin as an additive. Patent Document 2 describes that a resin composition with improved transparency is obtained by increasing the D-form content of polylactic acid. However, in the case of Patent Documents 1 and 2, the resulting resin composition has insufficient heat resistance, and in order to achieve certain heat resistance, it is necessary to greatly reduce the content of polylactic acid resin. There is a problem that an environmentally friendly resin composition cannot be obtained.

  Furthermore, Patent Document 3 describes that a (meth) acrylic acid ester copolymer is added to a polylactic acid resin. Acrylic resins such as methacrylic resin (PMMA resin) are extremely good in compatibility with polylactic acid resin, and maintain transparency after alloying with polylactic acid resin. There is. For this reason, it is widely used in various applications because of its transparency. Furthermore, it is widely used in applications that require performances other than transparency, taking advantage of its texture (hardness). The provision of low environmental impact to the acrylic resin by alloying the acrylic resin and the polylactic acid resin is a significant contribution, particularly in terms of fixing carbon dioxide.

  However, as in Patent Document 3, in alloying a polylactic acid resin and an acrylic resin, a resin composition having good compatibility can be obtained, but the heat resistance inherent in the acrylic resin is There is a problem that it is greatly damaged.

  Patent Document 4 describes that a methyl methacrylate polymer is blended with a polylactic acid resin. However, even in the case of Patent Document 4, the heat resistance of the obtained resin composition is insufficient.

No. 2005/123831 JP 2008-239836 A JP 2004-269720 A JP 2008-007594 A

  Therefore, this invention makes it a technical subject to solve said problem, and to provide the resin composition which contains a polylactic acid resin and is excellent in heat resistance and transparency.

  The present inventor has reached the present invention as a result of intensive studies to solve the above problems.

That is, the present invention has the following contents.
(1) 20 to 35% by mass of polylactic acid resin (A) and 65 to 80% by mass of methacrylic resin (B), and the total content of components other than polylactic acid resin (A) and methacrylic resin (B) is 10 A resin composition having a mass% or less, wherein the resin composition does not substantially contain a methyl acrylate segment represented by CH ₂ —CHCOOCH ₃ .
(2) The resin composition according to (1), wherein a deflection temperature under load at 0.45 MPa is 78 ° C. or higher.
(3) The resin composition according to (1) or (2), wherein the total light transmittance is 90% or more.
(4) A molded article obtained by molding the resin composition of any one of (1) to (3).

  The resin composition of the present invention is excellent in transparency because it has a polylactic acid resin and a methacrylic resin as main components and the total content of components other than both resins is 10% by mass or less. And since it does not contain a methyl acrylate segment substantially, it is excellent in heat resistance. In addition, the resin composition of the present invention has an advantage that it has a low environmental load. By using this resin composition for various applications, the range of use of polylactic acid resin, which is a low environmental load material, can be greatly expanded, and the industrial utility value is extremely high.

Hereinafter, the present invention will be described in detail.
The resin composition of the present invention essentially contains 20 to 35% by mass of the polylactic acid resin (A) and 65 to 80% by mass of the methacrylic resin (B). Furthermore, the resin composition of the present invention has a total content of components other than the polylactic acid resin (A) and the methacrylic resin (B) of 10% by mass or less, and is represented by CH ₂ —CHCOOCH ₃ in the resin composition. Which contain substantially no methyl acrylate segment.

  As the polylactic acid resin (A), poly (L-lactic acid), poly (D-lactic acid), and a mixture or copolymer thereof can be used in terms of heat resistance and moldability. Among these, from the viewpoint of biodegradability and moldability, it is preferable that poly (L-lactic acid) is mainly used.

  The melting point of the polylactic acid resin (A) is preferably 160 ° C. or higher in consideration of mechanical properties and heat resistance of the obtained molded body. In the polylactic acid resin (A), in order to make the melting point 160 ° C. or higher, the ratio of the D-lactic acid component may be less than about 3 mol%.

  Furthermore, it is particularly preferable that the polylactic acid resin (A) has a D-lactic acid component ratio of 0.6 mol% or less from the viewpoint of moldability when obtaining a molded body and heat resistance of the obtained molded body. . As the polylactic acid resin (A) in which the ratio of the D-lactic acid component is 0.6 mol% or less, a commercially available product can be suitably used. For example, “S-09, which is a polylactic acid resin manufactured by Toyota, Inc. ”,“ S-12 ”,“ S-17 ”, and the like.

  In the present invention, it is preferable to use a polylactic acid resin (A) having a low molecular weight from the viewpoint of transparency. Specifically, the melt flow rate (MFR) measured at a temperature of 210 ° C. and a load of 2.16 kg in accordance with JIS standard K-7210, which is an index of molecular weight, is 0.1 g / 10 min or more. , Preferably less than 400 g / 10 minutes. Especially, it is especially preferable that this MFR is 50 g / 10min or more and is less than 200 g / 10min. When the melt flow rate of the polylactic acid resin (A) is less than 0.1 g / 10 minutes, it may be undesirable from the viewpoint of operability at the time of processing, for example, when the components are kneaded, the load becomes extremely large. Further, when the melt flow rate of the polylactic acid resin (A) exceeds 400 g / 10 min, the molded product obtained from the resin composition of the present invention may be unfavorable in terms of mechanical properties. is there.

  As a method for adjusting the melt flow rate of the polylactic acid resin (A) to a predetermined range, when the melt flow rate is too large, a small amount of chain extender, for example, a diisocyanate compound, a bisoxazoline compound, an epoxy compound, A method of increasing the molecular weight of the polylactic acid resin (A) by using an acid anhydride or the like can be mentioned. On the other hand, when the melt flow rate of the polylactic acid resin (A) is too small, a method of mixing the polylactic acid resin with a polyester resin or a low molecular weight compound having a high melt flow rate can be mentioned. In the present invention, when a component other than a polylactic acid resin and a methacrylic resin such as a chain extender, a polyester resin, or a low molecular weight compound is used, the total content is 10% by mass or less of the entire resin composition. It is essential to do. The reason will be described later.

  The polylactic acid resin (A) used in the present invention is produced by a known melt polymerization method or by further using a solid phase polymerization method.

  In the resin composition of the present invention, the content of the polylactic acid resin (A) needs to be 20 to 35 mass%, preferably 20 to 30 mass%. If it is less than 20% by mass, the contribution to the environment is small. On the other hand, if it exceeds 35% by mass, the heat resistance and moldability are poor.

And the resin composition of this invention makes it essential to contain a methacryl resin (B) as mentioned above. The methacrylic resin (B) is polymethyl methacrylate (PMMA), which is a polymer material mainly composed of a methyl methacrylate polymer. Commercially available PMMA often contains vinyl monomer units other than methyl methacrylate units. And, in many cases, PMMA is contained 0.05 to 10 wt% of methyl acrylate segments _(CH 2 -CHCOOCH _3). On the other hand, the present inventor found for the first time the effect that the heat resistance of the resin composition is remarkably improved when a methacrylic resin substantially not containing a methyl acrylate segment is used, leading to the present invention.

Accordingly, in the present invention, as the methacrylic resin (B), it is necessary to use those which do not substantially containing methyl acrylate segments _(CH 2 -CHCOOCH _3). The methacrylic resin (B) substantially not containing the methyl acrylate segment (CH ₂ —CHCOOCH ₃ ) has improved heat resistance, and accordingly, the resin composition of the present invention containing such a methacrylic resin (B). Things also have improved heat resistance.

  In the present invention, “substantially no methyl acrylate segment” is measured and determined as follows.

Using a Fourier transform infrared spectrophotometer (manufactured by Shimadzu Corporation, “FTIR-8400S”), a sample is brought into close contact with a prism surface having a diameter of about 2 mm, and an infrared spectrum is measured. As a sample, a 2 mm-thick plate obtained by molding a methacrylic resin (B) at a mold surface temperature of 50 ° C. using an injection molding machine (manufactured by Toshiba Machine Co., Ltd., “IS-80G type”) is used. The measurement conditions are integration 120, decomposition 1 [1 / cm], and abbreviation Happ-Genzel. In the obtained infrared absorption (IR) spectrum, after confirming that a peak derived from a methyl methacrylate segment (810 cm ⁻¹ peak) appears clearly, a peak derived from a methyl acrylate segment (830 cm ⁻¹ peak) What does not exist is set as "substantially does not contain a methyl acrylate segment."

  The methacrylic resin (B) in the present invention preferably has a weight average molecular weight of 20,000 to 300,000, more preferably 50,000 to 250,000. When the weight average molecular weight exceeds 300,000, it becomes difficult to obtain compatibility with the polylactic acid resin (A). On the other hand, if it is less than 20,000, when it is set as the resin composition of this invention, physical properties, such as heat resistance and transparency which a methacryl resin (B) has, cannot be utilized, and it is not preferable. By using the methacrylic resin (B) having the above molecular weight, in an industrially useful melt-kneading method, the polylactic acid resin (A) and the methacrylic resin (B) are compatible with each other, and heat resistance and transparency are improved. A resin composition having excellent processability can be obtained.

  Further, the methacrylic resin (B) preferably has a deflection temperature under load at 1.8 MPa of 100 ° C. or higher, more preferably 105 ° C. or higher. When the deflection temperature under load is 100 ° C. or higher, there is an advantage that a resin composition having high heat resistance can be obtained.

  As such a methacrylic resin (B), for example, “Delagrass K” series which is a cast plate manufactured by Asahi Kasei Chemical Co., Ltd. can be used.

  In the resin composition of the present invention, the content of the methacrylic resin (B) needs to be 65 to 80% by mass, and preferably 70 to 80% by mass. If it is less than 65% by mass, the performance inherent in the methacrylic resin such as heat resistance cannot be exhibited sufficiently. On the other hand, if it exceeds 80% by mass, the content of the polylactic acid resin (A) becomes too small, and it becomes difficult to sufficiently exhibit low environmental impact.

  In the resin composition of the present invention, the content of components other than the polylactic acid resin (A) and the methacrylic resin (B) (hereinafter sometimes referred to as “other components”) may be 10% by mass or less. It is necessary and is preferably 2% by mass or less, more preferably 0.5% by mass or less. When content of another component exceeds 10 mass%, transparency of the resin composition obtained will fall.

  Examples of other components include glass fiber, talc, and hydrolysis inhibitor. Among these, glass fiber and talc are expected to have an effect of imparting heat resistance to the resin composition. However, when glass fiber or talc is contained, if the content exceeds 10% by mass, there is a problem that the transparency is remarkably lowered.

  In addition, when the resin composition of this invention contains the hydrolysis inhibitor as another component in the ratio of 10 mass% or less, the heat-and-moisture resistance (durability) of a resin composition is improved and the performance is prolonged. It becomes possible to maintain stably for a period.

  As the hydrolysis inhibitor, those having a carbodiimide compound as a main component are suitably used.

  As the carbodiimide compound, various compounds can be used, and any compound having one or more carbodiimide groups in the molecule is not particularly limited. Examples thereof include aliphatic monocarbodiimide, aliphatic polycarbodiimide, alicyclic monocarbodiimide, alicyclic polycarbodiimide, aromatic monocarbodiimide, and aromatic polycarbodiimide. Furthermore, you may have various heterocyclic rings or various functional groups in a molecule | numerator.

  It does not specifically limit as a method of manufacturing a carbodiimide compound, Many methods, such as the method of manufacturing an isocyanate compound as a raw material, are mentioned.

  As the carbodiimide compound, a carbodiimide compound having an isocyanate group in the molecule and a carbodiimide compound having no isocyanate group in the molecule can be used without distinction.

  As the carbodiimide skeleton of the carbodiimide compound, N, N′-di-o-triylcarbodiimide, N, N′-dioctyldecylcarbodiimide, N, N′-di-2,6-dimethylphenylcarbodiimide, N-triyl-N '-Cyclohexylcarbodiimide, N-triyl-N'-phenylcarbodiimide, N, N'-di-p-nitrophenylcarbodiimide, N, N'-di-p-hydroxyphenylcarbodiimide, N, N'-di-cyclohexylcarbodiimide N, N'-di-p-triylcarbodiimide, p-phenylene-bis-di-o-triylcarbodiimide, 4,4'-dicyclohexylmethanecarbodiimide, tetramethylxylylenecarbodiimide, N, N-dimethylphenylcarbodiimide , N, N′-di-2, - diisopropyl phenyl carbodiimide, include many carbodiimide skeleton.

  Specific examples of the carbodiimide compound include many compounds, and examples of the alicyclic monocarbodiimide include dicyclohexylcarbodiimide. Examples of the alicyclic polycarbodiimide include polycarbodiimide derived from 4,4′-dicyclohexylmethane diisocyanate. Examples of the aromatic monocarbodiimide include N, N′-diphenylcarbodiimide, N, N′-di-2,6-diisopropylphenylcarbodiimide and the like. In addition, examples of the aromatic polycarbodiimide include polycarbodiimide derived from phenylene-p-diisocyanate, polycarbodiimide derived from 1,3,5-triisopropyl-phenylene-2,4-diisocyanate, and the like.

  In polycarbodiimide, both ends of the molecule or any part of the molecule has a functional group such as an isocyanate group, or the molecular structure is different from other parts such as branched molecular chains. It does not matter if it is.

  In the resin composition of the present invention, the content of the hydrolysis inhibitor mainly composed of a carbodiimide compound is preferably 0.05% by mass or more, and more preferably 0.1% by mass. If it is less than 0.05% by mass, the intended durability may not be obtained. In addition, the upper limit of content of the carbodiimide compound which is another component is 10 mass%. This is because when the amount exceeds 10% by mass, the color tone of the resin composition is greatly impaired, and thus the transparency is poor as described above.

  In addition to the above, the resin composition of the present invention includes pigments, heat stabilizers, antioxidants, weathering agents, plasticizers, lubricants, mold release, as long as the effects of the present invention are not impaired. Agents, antistatic agents, and the like. Although it does not specifically limit as a flame retardant, For example, a phosphorus flame retardant, a metal hydroxide, etc. are mentioned. Examples of heat stabilizers and antioxidants include hindered phenols, hindered amines, sulfur compounds, copper compounds, alkali metal halides, and the like. In addition, the method of containing these other components in the resin composition of the present invention is not particularly limited.

As described above, the resin composition of the present invention comprises a polylactic acid resin (A) and a methacrylic resin (B) as main components, and even when it contains other components, the amount is 10% by mass or less. is there. Then, the resin composition of the present invention, it is necessary not to contain methyl acrylate segment represented by CH ₂ -CHCOOCH ₃ in the resin composition essentially. In order to satisfy this condition, as described above, it is necessary to use a methacrylic resin (B) that does not substantially contain a methyl acrylate segment represented by CH ₂ —CHCOOCH _3. It is also necessary to use a component that does not substantially contain the methyl acrylate segment represented by CH ₂ —CHCOOCH ₃ .

The resin composition of the present invention has significantly improved heat resistance by not containing substantially the methyl acrylate segment represented by CH ₂ —CHCOOCH ₃ in the resin composition. The resin composition of the present invention, the term "substantially free of methyl acrylate segments represented by CH ₂ -CHCOOCH _3." Is intended to determine measured as follows.

Using a Fourier transform infrared spectrophotometer (manufactured by Shimadzu Corporation, “FTIR-8400S”), a sample is brought into close contact with a prism surface having a diameter of about 2 mm, and an infrared spectrum is measured. As a sample, a 2 mm-thick plate obtained by molding the resin composition at a mold surface temperature of 50 ° C. using an injection molding machine (manufactured by Toshiba Machine Co., Ltd., “IS-80G type”) is used. The measurement conditions are integration 120, decomposition 1 [1 / cm], and abbreviation Happ-Genzel. In the obtained infrared absorption (IR) spectrum, after confirming that a peak derived from a methyl methacrylate segment (810 cm ⁻¹ peak) appears clearly, a peak derived from a methyl acrylate segment (830 cm ⁻¹ peak) What does not exist is set as "substantially does not contain a methyl acrylate segment."

  Furthermore, the resin composition of the present invention preferably has a deflection temperature under load at 0.45 MPa of 78 ° C. or higher, more preferably 80 ° C. or higher, as an index of excellent heat resistance. The deflection temperature under load was measured by using an injection molding machine (“IS-80G type” manufactured by Toshiba Machine Co., Ltd.) at a mold surface temperature of 50 ° C., and then preparing a test piece for general physical properties measurement (ISO type). 75, a deflection temperature under load (thermal deformation temperature) at a load of 0.45 MPa is measured.

  And as a parameter | index which is excellent in transparency, it is preferable that the total light transmittance is 90% or more, and it is preferable that the resin composition of this invention is 92% or more especially. The total light transmittance was measured using an injection molding machine (manufactured by Toshiba Machine Co., Ltd., “IS-80G type”) after preparing a test piece for measurement having a mold surface temperature of 50 ° C. and a thickness of 2 mm, and then JIS K- It is measured according to 7105.

  In order to produce the resin composition of the present invention, means for mixing the polylactic acid resin (A), the methacrylic resin (B), and other components as necessary is not particularly limited, but uniaxial or biaxial extrusion The method of melt-kneading using a machine is mentioned. In order to improve the kneading state, it is preferable to use a twin screw extruder. Here, the kneading temperature is preferably in the range of (melting point of polylactic acid resin + 5) ° C. to (melting point of polylactic acid resin + 100) ° C. The kneading time is preferably 20 seconds to 30 minutes. When the temperature is lower or shorter than this range, the kneading or reaction may be insufficient. Conversely, when the temperature is higher or longer than this range, the resin may be decomposed or colored. Absent.

  The resin composition of the present invention can be formed into various molded bodies by molding methods such as injection molding, blow molding, extrusion molding, inflation molding, vacuum forming after sheet processing, pressure forming, and vacuum / pressure forming. Especially, it is preferable to shape | mold by the injection molding method, In addition to a general injection molding method, gas injection molding, injection press molding, etc. are employable.

  An example of injection molding conditions suitable for the resin composition of the present invention is as follows. That is, it is appropriate that the cylinder temperature is equal to or higher than the melting point or flow start temperature of the resin composition, preferably 190 to 270 ° C. The mold temperature is suitably set to a temperature of (melting point −20) ° C. or lower of the resin composition. As mold temperature, 30 degreeC or more is preferable and 40-70 degreeC is especially preferable. If the cylinder temperature or the mold temperature is too low, the operability may become unstable, such as a short circuit occurring in the molded body, or may easily fall into an overload. On the other hand, if the cylinder temperature or the mold temperature is too high, the resin composition may be decomposed, and the strength of the resulting molded product may be reduced, or problems such as coloring may easily occur.

  Specific examples of the molded body using the resin composition of the present invention include the following. In other words, various parts and casings around personal computers, mobile phone parts and casings, other resin parts for electrical appliances such as OA equipment parts, bumpers, instrument panels, console boxes, garnishes, door trims, ceilings, floors, engine surroundings Examples include automotive resin parts such as panels. Moreover, it can also be set as a film, a sheet | seat, a hollow molded product, etc.

  The resin composition of the present invention is particularly useful in parts that require sufficient heat resistance and transparency among the above-mentioned applications.

  Hereinafter, the present invention will be described more specifically with reference to examples. The measuring method used for evaluation of the resin composition of an Example and a comparative example is as follows.

(1) Bending strength Bending strength was measured according to ISO 178 using the obtained test specimen for general physical property measurement (ISO type). In the present invention, those having a bending strength of 100 MPa or more are preferred in actual use.

(2) Heat resistance Using the obtained test piece for general physical property measurement (ISO type), the deflection temperature under load (thermal deformation temperature) at a load of 0.45 MPa was measured according to ISO 75.

(3) Transparency Using the obtained 2 mm thick plate, the total light transmittance (unit:%) was measured according to JIS K-7105.

(4) Moisture and heat resistance Two types of test specimens for measuring general physical properties (ISO type) were prepared, and one of them was subjected to measurement of bending strength in accordance with ISO 178 as in the above (1). Thereafter, the other test piece was subjected to a high temperature and high humidity treatment by exposure in a high temperature and high humidity environment at a temperature of 60 ° C. and a relative humidity of 95% RH for 300 hours, and then the bending strength was measured according to ISO 178. The bending strength retention rate was calculated by the following formula and used as an index of heat and humidity resistance.
Bending strength retention (%) = [(Bending strength after 300 hours) / (Untreated bending strength)] × 100

(5) Detection of methyl acrylate segment in resin composition Measurement was performed by the method described above, and the presence or absence was determined.

Moreover, the various raw materials used for the Example and the comparative example are as follows.
MFR represents the melt flow rate. The MFR of the polylactic acid resin is a value measured at 210 ° C. and a load of 2.16 kg, and the MFR of the acrylic resin is a value measured at 230 ° C. and 3.8 kg.

(1) Polylactic acid resin (A)
・ PLA-1
“PLA-3001D” manufactured by Nature Works (D-form content: 1.4%, MFR: 15-30 g / 10 min)
・ PLA-2
“PLA-6251D” manufactured by Nature Works (D-form content: 1.4%, MFR: 50 to 150 g / 10 min)
・ PLA-3
“PLA-4032D” manufactured by Nature Works (D-form content: 1.4%, MFR: 1 to 15 g / 10 min)
・ PLA-4
“S-12” manufactured by Toyota (D-form content: 0.1%, MFR: 6-10 g / 10 min)

(2) Methacrylic resin (B)
・ B-1
Asahi Kasei Chemical Co., Ltd. cast plate “Delagrass K000” (contains no methyl acrylate segment. Deflection temperature of load: 109 ° C.) with a pulverizer (“UC-140S” manufactured by Horai Tekkosha Co., Ltd.) And used as a powder.
・ B-2
“Acrypet VH” (methyl methacrylate / methyl acrylate copolymer resin) (containing methyl acrylate segment, MFR: 1 to 3 g / 10 min, deflection temperature under load: 100 ° C.), manufactured by Mitsubishi Rayon Co., Ltd.

(3) Other components [hydrolysis inhibitor]
・ E-1
Carbodiimide “EN160” manufactured by Matsumoto Yushi Co., Ltd.
[Filler]
・ E-2
Owens Corning, chopped glass fiber “FT592” (average fiber diameter 10 μm)
・ E-3
Made by Hayashi Kasei Co., Ltd., talc “MW-HST” (average particle size: 2-8 μm)

Example 1
Using a twin screw extruder (manufactured by Toshiba Machine Co., Ltd., “TEM37BS type”), PLA-1 is used as the polylactic acid resin (A) so as to be 26% by mass with respect to the total amount of the resin composition. ), B-1 was used in an amount of 74% by mass, both were dry blended, and supplied from the root supply port of the extruder. Next, extrusion was carried out while applying a vent under the conditions of a barrel temperature of 230 ° C., a screw rotation speed of 150 rpm, and a discharge of 20 kg / h to obtain a resin composition having the composition shown in Table 1.

  And the resin composition discharged from the front-end | tip of an extruder was cut into the pellet form, and the pellet of the resin composition was obtained. The obtained pellets were dried with hot air at 85 ° C. for 10 hours, and then a test piece for measuring general physical properties (ISO) at an mold surface temperature of 50 ° C. using an injection molding machine (Toshiba Machine Co., Ltd., “IS-80G type”). Type) and 2 mm thick plates were prepared and subjected to various measurements.

Examples 2-12, Comparative Examples 1-5
Resin composition in the same manner as in Example 1 except that the polylactic acid resin (A), methacrylic resin (B) and other components were changed in content and type to those shown in Tables 1 and 2. Got.

  The obtained resin composition was made into pellets as in Example 1, and the pellets were injection-molded in the same manner as in Example 1 to produce general physical property measurement specimens (ISO type) and 2 mm thick plates. The sample was subjected to various measurements.

なお、表１および表２中の組成における数値は、質量％を単位とする。

In addition, the numerical value in the composition of Table 1 and Table 2 makes mass% a unit.

  As is clear from Table 1, the resin compositions obtained in Examples 1 to 12 had a total of components other than the polylactic acid resin and the methacrylic resin of 10% by mass or less, and contained substantially no methyl acrylate segment. Therefore, it was excellent in heat resistance and transparency.

  Since the resin composition obtained in Example 9 contained talc as the other component, compared with Example 5, there was room for improvement in transparency.

  The resin composition obtained in Example 10 had a glass fiber content of 5% by mass, which was greater than the glass fiber content in the resin composition obtained in Example 8. When compared with the resin composition obtained in Example 8, there was room for improvement in transparency.

  Since the resin composition obtained in Example 11 contains 10% by mass of a carbodiimide compound which is a hydrolysis inhibitor, the content of the carbodiimide compound is 8% by mass, and the resin composition obtained in Example 6 In comparison, the heat resistance (bending strength retention) was excellent, but there was room for improvement in transparency.

  Since the resin composition obtained in Example 12 had a low D-form content as the polylactic acid resin (A), it was superior in heat resistance compared to Example 1-3.

  The resin composition obtained in Comparative Example 1 was inferior in heat resistance because a methacrylic resin containing a methyl acrylate segment was used.

  The resin composition obtained in Comparative Example 2 was inferior in heat resistance because a methacrylic resin containing substantially no methyl acrylate segment and a methacrylic resin containing a methyl acrylate segment were used in combination.

  The resin composition obtained in Comparative Example 3 contained a large amount of glass fibers as other components in excess of 10% by mass. As a result, the deflection temperature under load was improved, but the transparency was significantly inferior.

  The resin composition obtained in Comparative Example 4 was inferior in heat resistance because the polylactic acid resin (A) content was excessive and the methacrylic resin (B) content was excessive.

  Although the resin composition obtained in Comparative Example 5 contained a hydrolysis inhibitor as another component in a large amount exceeding 10% by mass, the heat and humidity resistance (bending strength retention rate) was improved. The result was inferior in transparency.

Claims (4)

It contains 20 to 35% by mass of polylactic acid resin (A) and 65 to 80% by mass of methacrylic resin (B), and the total content of components other than polylactic acid resin (A) and methacrylic resin (B) is 10% by mass or less. a resin composition is a resin composition characterized by containing substantially no methyl acrylate segment represented by CH ₂ -CHCOOCH ₃ to the resin composition.   The resin composition according to claim 1, wherein a deflection temperature under load at 0.45 MPa is 78 ° C or higher.   The resin composition according to claim 1 or 2, wherein the total light transmittance is 90% or more. The molded object formed by shape | molding the resin composition in any one of Claims 1-3.