JP2010070729A - Method for producing polylactic acid-based resin molding, and polylactic acid-based resin molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a polylactic acid-based resin molding excellent in moldability and heat resistance and exhibiting a practical temperature control with water, by maintaining a sufficient crystallization rate. <P>SOLUTION: A polylactic acid-based resin composition includes (A) a polylactic acid-based resin and (B) 0.1-1.0 wt.% of a trimesic acid compound. In the method for producing the polylactic acid-based resin molding, the composition is melted at a temperature of 230-250°C for 0.5-5.0 min and molded at a crystallization temperature of 70-90°C. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a polylactic acid-based resin molded article that is excellent in moldability and heat resistance by maintaining a sufficient crystallization rate and that can be practically controlled in water temperature. The present invention also relates to a polylactic acid resin molded body molded by the method.

  With the recent increase in environmental awareness, the demand for polylactic acid resin produced from non-petroleum resources is increasing. However, since the polylactic acid resin generally has a low crystallization speed, it takes a long time to crystallize the polylactic acid resin for the purpose of improving the heat resistance, so that the productivity is poor. For example, when the mold temperature is 80 ° C. or less in injection molding, there is a problem that crystallization does not proceed and the molded product cannot be removed from the mold, and the heat resistance of the molded product is low. When forming into a product exposed to a relatively high temperature, such as tableware, a cup or a home appliance without performing sufficient crystallization, the product (molded product) has a problem of causing thermal deformation and the like.

  As a means to solve such problems, the technology for blending polylactic acid resins with inorganic crystal nucleating agents such as talc, mica and calcium carbonate, and organic crystal nucleating agents are blended to improve the crystallization speed. The technology to make it known is known. However, the addition of the inorganic crystal nucleating agent has a problem that the flowability of the resin is lowered during molding, and the moldability is deteriorated.

  Therefore, various polylactic acid crystal nucleating agents for improving the crystallization rate of polylactic acid have been proposed. For example, Patent Documents 1 to 3 listed below disclose techniques in which a trimesic acid compound is blended as a crystal nucleating agent.

  In these conventional techniques, the crystallization (mold) temperature conditions are 100 ° C. and 30 ° C. A mold at 100 ° C. has oil temperature control (temperature control with oil), and a crystallization temperature of 80 ° C. or lower is desired for practical water temperature control (temperature control with water). Further, since the crystallization temperature at 30 ° C. is not higher than the glass transition temperature (softening temperature) of polylactic acid, polylactic acid does not crystallize and remains in an amorphous state, and crystallization at 70 to 90 ° C. (gold Mold) temperature is desired. Furthermore, in these conventional techniques, the crystal nucleating agent addition concentration (addition amount of the crystal nucleating agent) is preferably 0.05 to 5 parts by weight, and 0.2 to 1.5 parts by weight with respect to 100 parts of polylactic acid. Is only described as being particularly preferred. Since the crystal nucleating agent is expensive, it is desired that the amount added is small.

JP 2006-328163 A JP 2006-342259 A JP 2006-348159 A

  An object of this invention is to provide the manufacturing method of the polylactic acid-type resin molding which is excellent in a moldability and heat resistance by maintaining sufficient crystallization speed, and can perform practical water temperature control.

  As a result of measuring and examining the crystallization rate in detail by changing the crystal nucleating agent and the crystal nucleating agent addition concentration, the present inventors have used a specific crystal nucleating agent and a specific crystal nucleating agent addition concentration. In the present invention, it has been found that the crystallization speed is improved at a low crystallization temperature (70 to 90 ° C.) and in a low addition amount region (0.1 to 1.0 wt%) contrary to the conventional common sense. Reached.

  That is, first, the present invention is an invention of a method for producing a polylactic acid resin molded product from a polylactic acid resin composition containing (A) a polylactic acid resin and (B) a trimesic acid compound, A polylactic acid resin composition containing (A) a polylactic acid resin and (B) 0.1 to 1.0 wt% of a trimesic acid compound is melted at a melting temperature of 230 to 250 ° C., a melting time of 0.5 to 5 It is characterized by melting at 0 minutes and molding at a crystallization temperature of 70 to 90 ° C.

  When the addition of the trimesic acid compound is 0.1 wt% or less, the effect as a crystal nucleating agent does not appear. If it is 1.0 wt% or more, the crystallization rate is slow and material costs are also required. When the melting temperature is 230 ° C. or lower, the dispersibility of the crystal nucleating agent is inferior and the crystallization rate is slow. When it is 250 ° C. or higher, polylactic acid is decomposed and physical properties are lowered. When the melting time is 0.5 minutes or less, the dispersibility is poor and the crystallization rate is slow. If it is 5.0 minutes or more, polylactic acid is decomposed and physical properties are lowered. When the crystallization temperature is 70 ° C. or less, the crystallization of polylactic acid does not proceed. If it is 90 ° C. or higher, oil is required for temperature control, and special equipment must be introduced.

  As the trimesic acid compound, those known as crystal nucleating agents in the production of a polylactic acid-based resin molded product can be used. Among these, a trimesic acid triamide compound represented by the following general formula (1) is preferably exemplified.

［式中、Ｒ^１はトリメシン酸から全てのカルボキシル基を除いて得られる残基を表す。３個のＲ^２は同一又は相異なって、炭素数１〜４の直鎖状若しくは分岐鎖状のアルキル基を１〜３個有していてもよいシクロヘキシル基、又は炭素数１〜４の直鎖状若しくは分岐鎖状のアルキル基を表す。］

[Wherein R ¹ represents a residue obtained by removing all carboxyl groups from trimesic acid. Three R ^{2 s} are the same or different and are each a cyclohexyl group optionally having 1 to 3 linear or branched alkyl groups having 1 to 4 carbon atoms, or a straight chain having 1 to 4 carbon atoms. Represents a chain or branched alkyl group. ]

  In the present invention, the amount of trimesic acid compound added is 0.1 to 1.0 wt%, more preferably 0.3 to 0.5 wt%.

  In this invention, although the melting temperature of the polylactic acid-type resin composition used as a raw material is 230-250 degreeC, 235-245 degreeC is more preferable.

  In the present invention, the molding method is not particularly limited, and for example, injection molding, extrusion molding, injection blow molding, injection extrusion blow molding, injection compression molding, extrusion blow molding, extrusion thermoform molding, melt spinning, or the like is employed.

  Secondly, the present invention is a polylactic acid resin molded body produced by the above method. The polylactic acid resin molded product of the present invention has a high degree of crystallinity and excellent heat resistance.

  In the low crystallization temperature (70 to 90 ° C.) that has not been conventionally employed, and in the low addition amount region (0.1 to 1.0 wt%) contrary to the conventional technical common sense, the present invention This is an extremely practical technique because the crystallization speed of the resin molded body can be improved and water temperature control can be adopted. That is, by maintaining a sufficient crystallization rate, it became possible to produce a polylactic acid-based resin molded article having excellent moldability and heat resistance and capable of practical water temperature control.

  The polylactic acid resin used in the present invention is not particularly limited, and polylactic acid resins having lactic acid units having various optical purities can be used, but a structural unit composed of L-lactic acid residues (so-called L-lactic acid units). Or it is preferable that the structural unit (what is called D-lactic acid unit) which consists of D-lactic acid residues exists in the range of 80-99.5 mol% with respect to all the structural units which comprise polylactic acid-type resin. Such a polylactic acid resin is relatively easy to obtain and has a high melting point, so that it becomes easy to obtain a resin composition having better heat resistance. The structural unit consisting of L-lactic acid residue or D-lactic acid residue is more preferably in the range of 90 to 99.2 mol%, and 93 to 99 mol, based on all structural units constituting the polylactic acid resin. More preferably, it is in the range of%.

  Moreover, what is derived from L-lactic acid, D-lactic acid, DL-lactic acid, L-lactide, D-lactide, meso-lactide alone or a mixture thereof can be used as the polylactic acid resin. That is, it may be produced by direct dehydration condensation of lactic acid or by lactide ring-opening method.

  The polylactic acid-based resin may have other structural units other than lactic acid residues as long as the effects of the present invention are not impaired. The range is preferably 50 mol% or less, more preferably It is 20 mol% or less. Examples of such other structural units include aliphatic dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and azelaic acid, and aliphatic glycols such as ethylene glycol, propylene glycol, and 1,4-butanediol. Hydroxycarboxylic acid units derived from the above; units of hydroxycarboxylic acids such as glycolic acid, β-hydroxybutyric acid, hydroxypivalic acid, and hydroxyvaleric acid.

  In the present invention, the molecular weight of the polylactic acid resin is not particularly limited, but the number average molecular weight (Mn) is preferably in the range of 5,000 to 400,000, and preferably 10,000 to 200,000. More preferred. When the number average molecular weight (Mn) is smaller than 5,000, when a molded product is produced using the obtained resin composition, the strength thereof decreases, the acid component content increases, the hydrolyzability increases, etc. This tends to reduce the stability. On the other hand, when it is larger than 400,000, the moldability tends to deteriorate when the resulting resin composition is molded.

  In addition, the polylactic acid-type resin used by this invention may use what was induced | guided | derived from a plant from the point of availability, L- or D-methyl lactate, L- or D-ethyl lactate. It is also possible to use a product produced from a lactic acid derivative such as a raw material (monomer) or a product produced by a microorganism.

  A trimesic acid triamide compound suitable as (B) trimesic acid compound which is a crystal nucleating agent used in the present invention is represented by the following general formula (1).

［式中、Ｒ^１はトリメシン酸から全てのカルボキシル基を除いて得られる残基を表す。３個のＲ^２は同一又は相異なって、炭素数１〜４の直鎖状若しくは分岐鎖状のアルキル基を１〜３個有していてもよいシクロヘキシル基、又は炭素数１〜４の直鎖状若しくは分岐鎖状のアルキル基を表す。］
で表される。

[Wherein R ¹ represents a residue obtained by removing all carboxyl groups from trimesic acid. Three R ^{2 s} are the same or different and are each a cyclohexyl group optionally having 1 to 3 linear or branched alkyl groups having 1 to 4 carbon atoms, or a straight chain having 1 to 4 carbon atoms. Represents a chain or branched alkyl group. ]
It is represented by

  There is no particular limitation on the production method of the trimesic acid triamide compound, for example, trimesic acid or its acid chloride and a cyclohexylamine optionally having a linear or branched alkyl group having 1 to 4 carbon atoms, or It can be obtained by amidating a linear or branched alkylamine having 1 to 4 carbon atoms.

  Specific examples of the cyclohexylamine optionally having a linear or branched alkyl group having 1 to 4 carbon atoms include cyclohexylamine, 2-methylcyclohexylamine, 3-methylcyclohexylamine, 4-methyl. Cyclohexylamine, 2-ethylcyclohexylamine, 3-ethylcyclohexylamine, 4-ethylcyclohexylamine, 2-n-propylcyclohexylamine, 3-n-propylcyclohexylamine, 4-n-propylcyclohexylamine, 2-iso-propyl Cyclohexylamine, 3-iso-propylcyclohexylamine, 4-iso-propylcyclohexylamine, 2-n-butylcyclohexylamine, 3-n-butylcyclohexylamine, 4-n-butylcyclohexylamine, -Iso-butylcyclohexylamine, 3-iso-butylcyclohexylamine, 4-iso-butylcyclohexylamine, 2-sec-butylcyclohexylamine, 3-sec-butylcyclohexylamine, 4-sec-butylcyclohexylamine, 2-tert -Butylcyclohexylamine, 3-tert-butylcyclohexylamine, 4-tert-butylcyclohexylamine, 2,3-dimethylcyclohexylamine, 2,4-dimethylcyclohexylamine, 2,5-dimethylcyclohexylamine, 2,6-dimethyl Cyclohexylamine, 2,3,4-trimethylcyclohexylamine, 2,3,5-trimethylcyclohexylamine, 2,3,6-trimethylcyclohexylamine, 2,4,6-trimethyl Chill cyclohexylamine, 3,4,5-trimethyl cyclohexylamine, and the like. Specific examples of the linear or branched alkylamine having 1 to 4 carbon atoms include methylamine, ethylamine, n-propylamine, iso-propylamine, n-butylamine, iso-butylamine, sec-butylamine, tert -Butylamine is mentioned.

  Among the trimesic acid triamide compounds, a triamide compound having a cyclohexane ring is preferable because it is particularly excellent in improving the crystallization speed of the polylactic acid resin. For example, trimesic acid tricyclohexylamide, trimesic acid tri (2-methylcyclohexylamide), trimesic acid tri (3-methylcyclohexylamide), trimesic acid tri (4-methylcyclohexylamide), trimesic acid tri (2,3-dimethyl) Cyclohexylamide) is preferred, and trimesic acid tricyclohexylamide and trimesic acid tri (2-methylcyclohexylamide) are particularly preferred.

  The trimesic acid triamide compounds can be used alone or in admixture of two or more.

  The shape of the trimesic acid triamide compound is not particularly limited, but an average particle size of 10 μm or less and a maximum particle size of 30 μm or less are preferable, and an average particle size of 5 μm or less and a maximum particle size of 20 μm or less are particularly preferable. When the average particle size is larger than 10 μm or the maximum particle size is larger than 30 μm, the dissolution of the trimesic acid triamide compound in the polylactic acid resin is insufficient, and the nucleation action on the polylactic acid resin tends to be reduced. There is. As a result, the relative crystallinity of the obtained molded product is lowered, and the heat resistance tends to be lowered. Here, the maximum particle size refers to a particle size in which the percentage of the particle amount smaller than the particle size is 99% with respect to the total particle amount when measured by the method described in Examples described later.

  The lactic acid resin composition used as a starting material in the present invention can contain a carbodiimide compound as necessary. The carbodiimide compound exhibits an effect of suppressing hydrolysis of the polylactic acid resin by performing a crosslinking reaction with the terminal carboxylic acid of the polylactic acid resin.

  The carbodiimide compound is not particularly limited as long as it has one or more carbodiimide groups in the molecule. For example, a carbodiimide compound synthesized by a decarboxylation reaction from an isocyanate compound according to a conventionally known method can be used. Moreover, you may use what is marketed. Examples of the monocarbodiimide compound having one carbodiimide group in the molecule include aliphatic or alicyclic monocarbodiimides such as diisopropylcarbodiimide, dicyclohexylcarbodiimide and dioctylcarbodiimide, and aromatic monocarbodiimides such as diphenylcarbodiimide. As an isocyanate compound in the synthesis of a polycarbodiimide having two or more carbodiimide groups in the molecule, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2 Aromatic diisocyanates such as 1,4-tolylene diisocyanate, tetramethylxylylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate; Nert, 1-methyl-2,4-cyclohexane diisocyanate, 1-methyl-2,6-cyclohexane diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, etc. The aliphatic Alicyclic diisocyanate and the like are.

  The polycarbodiimide may have all or part of the isocyanate group remaining at the end sealed, and as such a sealing agent, monoisocyanate such as cyclohexyl isocyanate, phenyl isocyanate, tolyl isocyanate, etc. Compound: Compounds having active hydrogen such as hydroxyl group and amino group are exemplified. Among the carbodiimide compounds, polycarbodiimide having two or more carbodiimide groups in the molecule is preferable from the viewpoint of improving hydrolysis resistance of a molded product molded from the obtained resin composition. Polycarbodiimide obtained from aliphatic or alicyclic carbodiimide, aliphatic or alicyclic diisocyanate is preferable from the viewpoint of the compatibility of the above and the hydrolysis resistance of a molded product molded from the resulting resin composition. In the present invention, as the carbodiimide compound, one or more kinds of compounds can be used.

  When a carbodiimide compound is used, it can be appropriately changed according to each application, but is preferably 0.2 to 5 wt% with respect to 100 parts by weight of the polylactic acid resin used, and 0.5 to 2. More preferably, it is 5 wt%.

  In the lactic acid resin composition used as a starting material in the present invention, dibasic sulfate, dibasic lead stearate, calcium hydroxide, calcium silicate, etc. Inorganic additives, lubricants, pigments, impact resistance improvers, processing aids, reinforcing agents, colorants, flame retardants, weather resistance improvers, UV absorbers, antioxidants, hydrolysis resistance improvers, fungicides Agents, antibacterial agents, light stabilizers, antistatic agents, silicone oil, antiblocking agents, mold release agents, foaming agents, various additives such as fragrances; various fibers such as glass fibers and polyester fibers; silica, wood flour, etc. Filler; optional components such as various coupling agents can be blended as required.

  Furthermore, the lactic acid resin composition used as a starting material in the present invention is a polyurethane resin; a polyamide resin; a polyester resin; a polyvinyl chloride resin; a polyvinylidene chloride resin; Resin; Polyoxymethylene resin; Saponified ethylene-vinyl acetate copolymer; Acrylic resin such as polyacrylate, polymethacrylate, polymethyl methacrylate, methyl methacrylate-acrylic acid ester copolymer; Cyanide with aromatic vinyl compound Contains vinyl resin copolymer; aromatic vinyl compound-vinyl cyanide compound-olefin compound copolymer; methyl methacrylate-styrene-butylene copolymer; other resins such as styrene polymer and olefin polymer You may do it.

  The lactic acid resin composition used as a starting material in the present invention can be obtained by kneading the above components. There is no restriction | limiting in particular as the kneading | mixing method of each component, It can mix by a conventionally well-known method. For example, a dry blend method in which each component is charged and mixed in a tumbler, V-type blender, ribbon blender, Hellshell mixer, tumbler mixer, etc., and the dry blend is further mixed with a single screw or twin screw extruder, kneader, roll, etc. The method of melt-kneading above the melting temperature of lactic acid-type resin, cooling, and pelletizing is mentioned. Moreover, the solution blend method etc. which dissolve each resin in a solvent and remove a solvent after mixing are mentioned.

  In the present invention, the crystallization time is a time required for completion of heat generation due to crystallization as measured by a differential scanning calorimeter (DSC).

  The polylactic acid-based resin molded product of the present invention can be easily molded into molded products of various shapes by known molding methods such as extrusion molding, injection molding, calendar molding, vacuum molding, and pressure molding, The obtained molded body can be a molded body having excellent heat resistance. It can also be formed into a fiber by melt spinning.

  In the present invention, the “melting temperature” of the trimesic acid compound to the molten polylactic acid resin is obtained by heating the resin composition (pellet or dry blend) containing the trimesic acid compound under an optical microscope. The temperature at which the trimesic acid compound is dissolved in the resin and no solid is observed. In addition, in the case of injection molding, whether or not the trimesic acid compound is dissolved in the molten polylactic acid resin can be easily determined by visually observing the molten resin composition coming out from the nozzle tip of the heating cylinder. it can. That is, if the trimesic acid compound is not completely dissolved in the molten polylactic acid-based resin and any solid remains, the molten resin composition is cloudy. There is no transparency. Similarly, in extrusion molding, it can be confirmed whether or not the molten resin composition is completely dissolved by visual observation of the transparency of the molten resin composition discharged from the die. In the case of other molding methods, it can be confirmed in the molding step whether the molten resin composition discharged from the cylinder nozzle or the die is completely dissolved by visual observation.

  Further, kneading so that the solid trimesic acid compound does not exist can be carried out by adjusting the residence time of the resin composition during heating and melting, the screw rotation speed, and the like. Next, while maintaining this molten state, the resin composition is subjected to a molding step to cool and crystallize the resin composition.

  The molded body produced in the present invention is, for example, a vehicle part, a housing such as a body of a household electrical appliance, a gear, general goods, clothing, a bag, a fastening member such as a fastener or a button, agricultural material, building material, civil engineering It can be suitably used as materials, tableware, toys and the like.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Measurement methods and chemicals used in the following examples and comparative examples are as follows.
[sample]
Polylactic acid resin: CSL40830-2 (Mn = 10.5 × 10 ⁵ , Mw = 2.15 × 10 ⁵ , OP = 98.1%, manufactured by Toyota Motor Corporation)
Trimesic acid compound (crystal nucleating agent): NJester TF-1 (manufactured by Shin Nippon Rika Co., Ltd., hereinafter abbreviated as “TF-1”)

[Molding / Experiment Method; Laboratory Scale Experiment]
1) Mixing of materials: A polylactic acid resin and a crystal nucleating agent were dissolved and mixed in chloroform.
2) Collection of material: The mixed solution was left to dry at room temperature.
3) Experimental sample preparation: The sample was further dried at 70 ° C. for 4 hours and then pressed at 210 ° C. to prepare a sample.
4) Crystallization rate measurement: After the sample was melted at 240 ° C. or 200 ° C. for 1 minute, it was rapidly cooled to 80 ° C. using a rapid heating stage. Using a monochromatic X-ray with a light source wavelength of 0.1 nm, the time change of the peak area of the (110) plane of the polylactic acid crystal was measured, and the crystallization behavior at 80 ° C. was measured.

As shown in FIG. 1, the crystallization rate (v) described in the present invention is the time (half crystallization time (t _1/2 )) when crystallization is half completed in the isothermal crystallization measurement. The reciprocal (v = 1 / t _1/2 ).

  Table 1 below shows a list of TF-1 addition concentration, melting temperature; crystallization rate when 240 ° C, and melting temperature; crystallization rate when 200 ° C. FIG. 2 shows the correlation between the crystal nucleating agent addition concentration (wt%, TF-1 addition concentration) and the crystallization rate when the melting temperature is 200 ° C. Further, FIG. 3 shows the correlation between the crystal nucleating agent addition concentration (wt%, TF-1 addition concentration) and the crystallization rate when the melting temperature is 240 ° C.

  From the results of Table 1, FIG. 2 and FIG. 3, when the melting temperature is 200 ° C., there is no correlation between the crystallization nucleating agent addition concentration (wt%, TF-1 addition concentration) and the crystallization speed. When the melting temperature is 240 ° C., a specific improvement in the crystallization rate is observed in the range of 0.1 to 1.0 wt% of the crystal nucleating agent addition concentration (TF-1 addition concentration).

[Comparison with other crystal nucleating agents]
In addition to the combination of the above polylactic acid (PLA) and trimesic acid compound (crystal nucleating agent, TF-1), it was compared with a combination with another commercially available crystal nucleating agent. Table 2 below shows the crystallization rate at a crystallization temperature of 80 ° C. of the combined composition of polylactic acid (PLA) and various crystal nucleating agents.

Various crystal nucleating agents
TLA114; Takemoto Yushi Co., Ltd., Sulfoisophthalic acid dimethyl barium salt PPA-Zn; Eco Promote, Nissan Chemical Co., Ltd., zinc phenylphosphonate Talc; Microace, Nippon Talc Co., Ltd., Talc WX-1; River Ken Fine Chemical Co., Ltd., 12-hydroxystearic acid ethylene bisamide.

  From the results shown in Table 2, even when the crystallization temperature is 80 ° C., a remarkable crystallization rate cannot be expected even if a crystal nucleating agent other than the trimesic acid compound (TF-1) is added. It can be seen that this is a specific improvement in the crystallization rate by the trimesic acid compound (TF-1).

[Mixing by melt kneading, experiment using an injection molding machine]
Differences from the above embodiment are as follows.
1) Different commercially available polylactic acid materials were used.
2) A melt kneading method was used instead of a polylactic acid and nucleating agent mixing method using a solvent.
3) The polylactic acid was crystallized in the mold by injection molding, not by an experimental apparatus using a small amount of sample.

Specifically, the following procedure was used.
1) Mixing of materials: Polylactic acid resin (99%) and crystal nucleating agent (1%) were mixed by dry blending.
2) Biaxial kneading of materials: The mixed materials (polylactic acid resin and crystal nucleating agent) were kneaded with a biaxial kneader.
Kneading conditions: kneading temperature 210 ° C., screw rotation speed (100 to 200 rpm), material supply rate (2.5 kg / h)
3) Injection molding conditions: resin temperature 240 ° C., resin residence time in cylinder 1 minute, mold temperature 80 ° C., cooling time 120 seconds 4) Crystallinity: measured using DSC. Cut out the surface layer of the injection-molded specimen and measured. Temperature rising rate 10 ° C./min. The latent heat of fusion at the time of 100% crystallization of PLA was calculated as 93 J / g.
5) Crystallization speed: A film was prepared by using a hot press machine at 200 ° C. for the test piece that was injection molded. The sample was melted for 1 minute at 240 ° C., rapidly cooled to 80 ° C. using a rapid heating stage, and the crystallization rate was calculated by the method described above.

  The following Table 4 and FIG. The content of 1-4 and the result of the injection molding evaluation of the melt-kneaded sample are shown. The mold temperature is 80 ° C.

  Polylactic acid is as shown in Table 3 below.

As a result of Table 4, the following was found.
1) An improvement in the crystallization speed was observed even when different commercially available polylactic acid materials were used and the melt kneading method was used.
Furthermore,
2) Also in the melt-kneaded sample, the crystallization rate is faster when the addition amount of the nucleating agent is 0.5 wt% than when the addition amount is 1.0 wt%.
3) The crystallinity of the injection-molded product is also higher when the addition amount of the nucleating agent is 0.5 wt% than when 1.0 wt% is added.
4) The HDT of the injection-molded product is also higher when the addition amount of the crystal nucleating agent is 0.5 wt% than when 1.0 wt% is added.

  The present invention is a highly practical technique in which water temperature control can be adopted by setting the crystallization temperature in a low temperature range (70 to 90 ° C.) and the amount of expensive nucleating agent added is reduced. The obtained polylactic acid-based resin molded body has high crystallinity and excellent heat resistance.

It is an isothermal crystallization curve figure which shows the definition of crystallization rate (v). The graph shows the correlation between the crystal nucleating agent addition concentration (wt%, TF-1 addition concentration) and the crystallization rate when the melting temperature is 200 ° C. The graph shows the correlation between the crystal nucleating agent addition concentration (wt%, TF-1 addition concentration) and the crystallization rate when the melting temperature is 240 ° C. Melt-kneaded sample No. The content of 1-4 and the result of the injection molding evaluation of the melt-kneaded sample are shown.

Claims (6)

  A polylactic acid resin composition containing (A) a polylactic acid resin and (B) 0.1 to 1.0 wt% of a trimesic acid compound is melted at a melting temperature of 230 to 250 ° C., a melting time of 0.5 to 5 A method for producing a polylactic acid-based resin molded article, characterized by melting in 0 minutes and molding at a crystallization temperature of 70 to 90 ° C. The method for producing a polylactic acid-based resin molded article according to claim 1, wherein the (B) trimesic acid compound is a trimesic acid triamide compound represented by the following general formula (1).

[Wherein R ¹ represents a residue obtained by removing all carboxyl groups from trimesic acid. Three R ^{2 s} are the same or different and are each a cyclohexyl group optionally having 1 to 3 linear or branched alkyl groups having 1 to 4 carbon atoms, or a straight chain having 1 to 4 carbon atoms. Represents a chain or branched alkyl group. ]   The method for producing a polylactic acid-based resin molded article according to claim 1 or 2, comprising a trimesic acid compound in an amount of 0.3 to 0.5 wt%.   The method for producing a polylactic acid-based resin molded article according to any one of claims 1 to 3, wherein the melting temperature is 235 to 245 ° C.   5. The molding according to claim 1, wherein the molding is injection molding, extrusion molding, injection blow molding, injection extrusion blow molding, injection compression molding, extrusion blow molding, extrusion thermoform molding, or melt spinning. The manufacturing method of the polylactic acid-type resin molding of description.   The polylactic acid-type resin molding manufactured by the method in any one of Claims 1 thru | or 5.

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