JP2016060048A - Polylactic acid strand - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polylactic acid strand suitable for materials of three-dimensional molding capable of high accuracy and stable melting sedimentation molding, a manufacturing method therefor, a manufacturing method of a three-dimensional molded article using the polylactic acid strand and the three-dimensional molded article.SOLUTION: There is provided a polylactic acid strand having an average diameter of 1.0 to 3.5 mm, a diameter variation rate represented by the formula (iii-1) of 3% or less and a diameter variation width represented by the formula (iii-2) of 15% or less and a thermal shrinkage when immersed in silicone oil held at the melting point of the sample for 1 minute of 10% or more. Diameter variation rate (%)=σ/D×100(iii-1), Diameter variation width (%)=(D-D)/D×100(iii-2), where σ: standard deviation of outer diameter, D: average of outer diameter (mm), D: maximum value of outer diameter and D: minimum value of outer diameter.SELECTED DRAWING: None

Description

  The present invention relates to a material suitable for three-dimensional modeling and a three-dimensional modeling method.

2. Description of the Related Art Conventionally, there is known a technique for performing three-dimensional modeling by sequentially laminating a resin for each cross section obtained by cutting a modeling target by a plurality of parallel surfaces, and generating a modeling target that becomes a three-dimensional model of the modeling target. . Such a technique is called three-dimensional modeling, and can be used for component prototyping and product manufacturing.
As a three-dimensional modeling method, an optical modeling method using a photocurable resin, a powder lamination method using a metal or resin powder, a melt deposition method in which a resin is melted and deposited, a paper, a resin sheet, or a thin metal plate is laminated. A thin plate laminating method, an ink jet method in which a liquid or powdered resin or metal is jetted are known.

  As an example of the melt deposition method, Patent Document 1 discloses a melt deposition method using a thermoplastic polymer material. In this technique, a solid thermoplastic polymer material is supplied to a discharge head, the polymer material is melted in the discharge head, and the molten polymer material is discharged from the discharge head and deposited in layers. repeat. The thermoplastic polymers that can be used in this technology are polyethersulfone, polyetherimide, polyphenylsulfone, polyphenylene, polycarbonate, high impact polystyrene, polysulfone, polystyrene, acrylic resin, amorphous polyamide, polyester, nylon, PEEK. And ABS are illustrated. In particular, polylactic acid, which is a plant-derived thermoplastic polyester, is suitably used in this method because it can be melted and discharged at a relatively low temperature and has a superior environmental load.

One of the problems of the melt deposition method using polylactic acid is the problem of dripping. Since general polylactic acid has a glass transition temperature of about 60 ° C. and is in a solid state at room temperature, it is solidified by cooling the molten resin from the discharge head to near room temperature, and a desired three-dimensional model. Can be formed. However, if the discharged molten resin is not cooled quickly, it is in a rubber state until the temperature of the resin falls below the glass transition point, so the resin can easily move from the desired position due to gravity or contact with the discharge head. Therefore, there is a problem that a desired three-dimensional model shape is not formed.
For example, FIG. 1 is a diagram of a modeling apparatus viewed from the side while a three-dimensional model having a bridge-like structure is being modeled using a melt deposition modeling apparatus. Reference numeral 1 denotes an ejection head, and 2 denotes a laminated bed. 3 represents a bridge girder structure that has already been formed. A portion surrounded by a dotted line 4 represents a design drawing of a bridge-like structure to be formed. Since the discharge head 1 discharges resin as shown in this design drawing, the resin is discharged from the tip under the discharge head. Although the resin moves from the left to the right while being discharged, the discharged resin hangs down due to the action of gravity as represented by 5 and the desired structure represented by 4 may not be obtained.

  As a second problem, there is a problem of ejection speed stability. In the melt deposition method, a strand formed by linearly molding the thermoplastic resin is generally used. The modeling by the melt deposition method is automatically performed according to a predetermined program, and the resin supply speed is set each time according to the moving speed of the discharge head, so that a desired three-dimensional model can be modeled. However, if the strand cannot be supplied to the discharge head for some reason, such as clogging in the supply path, or if the strand falls greatly from the assumed resin supply amount, the resin can be stably delivered according to the discharge speed set by the program. As a result of not being discharged, a desired three-dimensional model cannot be formed.

As a third problem, there is a problem of responsiveness of the discharge speed control. In order to form a desired three-dimensional model, the discharge speed of the molten resin needs to be accurately controlled. During molding, the molten resin is not always discharged at a constant discharge volume.When the discharge is not necessary, the discharge is stopped, and if the movement speed of the discharge head is reduced, the discharge speed must be reduced accordingly. Yes, this discharge rate increase / decrease control is frequently repeated during modeling. A diagram of a general melt deposition modeling apparatus is disclosed in Patent Document 2. As shown in this figure, in a general melt deposition modeling apparatus, in order to simplify parts, a device such as a gear pump that measures molten resin and supplies it to a discharge port at a predetermined speed is not used. A method of controlling the discharge speed of the molten resin by using the characteristics as a solid and controlling the speed (feed speed) of feeding the strand to the discharge nozzle is used. However, since a strand made of a thermoplastic polymer material that itself flows through a rubber state by heating is used like a piston, between the increase / decrease control of the strand feed speed and the actual increase / decrease of the discharge speed that occurs as a result. As a result of the occurrence of a slight time lag, there is a problem of responsiveness of the discharge speed control that a desired three-dimensional shape is not accurately formed.
As described above, there are many problems in the polylactic acid strand for melt deposition modeling.

JP-T-2005-53439 Japanese Patent Laid-Open No. 3-158228

  An object of the present invention is to provide a polylactic acid strand suitable for a three-dimensional modeling material that solves the above-described conventional problems and enables highly accurate and stable melt deposition modeling, and a method for producing the same. Another object of the present invention is to provide a method for producing a three-dimensional structure using a polylactic acid strand and a three-dimensional structure.

The present inventors diligently studied about a polylactic acid strand for three-dimensional modeling that enables highly accurate and stable melt deposition modeling. As a result, it has been found that by using a strand having a high heat shrinkage at the melting point as a material, the problem of dripping at the time of modeling can be solved. In addition, strands with precisely controlled diameters are used as materials, and the thermal and structural properties of the strand surface are highly controlled to improve discharge speed stability and discharge speed control responsiveness. The present invention was completed by finding that a desired three-dimensional structure can be obtained accurately and with high accuracy.
That is, the present invention includes the following.

1. The average value of the diameter is 1.0 to 3.5 mm, the diameter variation rate represented by the following formula (iii-1) is 3% or less, and the diameter variation range represented by the following formula (iii-2) is A polylactic acid strand having a heat shrinkage of 10% or more when immersed for 1 minute in silicone oil held at the melting point of the sample at 15% or less.
Diameter variation rate (%) = σ / D × 100 (iii-1)
Diameter fluctuation range (%) = (D _Max −D _Min ) / D × 100 (iii-2)
σ: Standard deviation of outer diameter D: Average value of outer diameter (mm)
D _Max : Maximum outer diameter D _Min : Minimum outer diameter

2. 2. The polylactic acid strand according to 1 above, wherein a portion having a thickness of (diameter / 4) satisfies the following A from the surface of the strand.
A: In the spectrum analyzed by the temperature rise DSC, the temperature at the top of the crystal melting peak is 140 ° C. or higher, the calorie of the melting peak is 30 J / g or higher, and the half width of the melting peak is 20 ° C. or lower.

3. The average value of the diameter is 1.0 to 3.5 mm, the diameter variation rate represented by the following formula (iii-1) is 3% or less, and the diameter variation range represented by the following formula (iii-2) is 15 Is a method for producing a polylactic acid strand having a heat shrinkage rate of 10% or more when immersed in a silicone oil held at the melting point of the sample for 1 minute,
Diameter variation rate (%) = σ / D × 100 (iii-1)
Diameter fluctuation range (%) = (D _Max −D _Min ) / D × 100 (iii-2)
σ: Standard deviation of outer diameter D: Average value of outer diameter (mm)
D _Max : Maximum value of outer diameter D _Min : Minimum value of outer diameter (i) Polylactic acid resin having a lactic acid content of 50% or more, a molecular weight of 100,000 to 350,000, and a melting point of 140 to 180 ° C. is 200. Melted at ~ 240 ° C,
(Ii) The molten polylactic acid resin is extruded from a base at 230 to 260 ° C. to form a filamentous material,
(Iii) The filamentous material is cooled and solidified in cooling water at a temperature of Tg to (Tg + 20) ° C. in a range of 1 to 5 cm from the base surface to the liquid level of the water-cooled bath, and then water or air at 0 to 30 ° C. And again, solidify by cooling to make a strand,
(Iv) The cooled strand is taken up at a speed of 5 to 20 m / min, stretched in a single stage or multiple stages at a magnification of 1.5 to 3 times at 80 to 120 ° C., and (v) the stretched strand When it is drawn at the same speed as stretching, it is cooled and solidified with air at 10 to 30 ° C.,
The manufacturing method of the polylactic acid strand containing each process.

4). 4. The production method according to 3 above, comprising a step of heat-treating at 80 to 100 ° C. after stretching, wherein the portion of the thickness (diameter / 4) satisfies the following A from the surface of the obtained polylactic acid strand.
A: In the spectrum analyzed by the temperature rise DSC, the temperature at the top of the crystal melting peak is 140 ° C. or higher, the calorie of the melting peak is 30 J / g or higher, and the half width of the melting peak is 20 ° C. or lower.
5. (I) The polylactic acid strand is supplied to the discharge head, the polylactic acid strand is melted in the discharge head, and (ii) the melted polylactic acid is discharged from the discharge head to a specified position and deposited in layers. Solidify lactic acid,
A method for producing a three-dimensional structure including each step and repeating each step (i) to (ii), wherein the polylactic acid strand according to 1 or 2 is used as a polylactic acid strand. A method for manufacturing a three-dimensional structure.
6). A three-dimensional structure using a polylactic acid strand obtained by the production method described in 3 or 4 above.

  According to the present invention, it is possible to obtain a polylactic acid strand capable of obtaining a desired three-dimensional shaped article stably and with high accuracy in melt lamination modeling.

It is the figure which looked at the modeling apparatus from the side during modeling using a melt deposition modeling apparatus, and the bottom of the place which discharges resin is hollow, and it was discharged. It is a figure showing the condition where resin has dripped. It is the schematic showing an example of the apparatus suitable for manufacturing the polylactic acid strand of this invention.

  Hereinafter, the present invention will be described in detail.

<Polylactic acid strand>
The polylactic acid strand in the present invention is obtained by forming a polymer material containing polylactic acid as a main component into a strand shape. A main component is 50 weight% or more of a structural component.

  Here, polylactic acid consists of lactic acid units whose main chain is mainly represented by the following formula (1). In this specification, “mainly” is preferably a ratio of 90 to 100 mol%, more preferably 95 to 100 mol%, and still more preferably 98 to 100 mol%.

  The lactic acid unit represented by the formula (1) includes an L-lactic acid unit and a D-lactic acid unit, which are optical isomers. The main chain of the polylactic acid is preferably mainly an L-lactic acid unit, a D-lactic acid unit or a combination thereof.

The polylactic acid is preferably poly D-lactic acid whose main chain is mainly composed of D-lactic acid units, and poly L-lactic acid whose main chain is mainly composed of L-lactic acid units. The proportion of other units constituting the main chain is preferably in the range of 0 to 10 mol%, more preferably 0 to 5 mol%, and still more preferably 0 to 2 mol%.
Examples of other units constituting the main chain include units derived from dicarboxylic acids, polyhydric alcohols, hydroxycarboxylic acids, lactones and the like.

  Examples of the dicarboxylic acid include succinic acid, adipic acid, azelaic acid, sebacic acid, terephthalic acid, and isophthalic acid. Examples of the polyhydric alcohol include aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, octanediol, glycerin, sorbitan, neopentyl glycol, diethylene glycol, triethylene glycol, polyethylene glycol, and polypropylene glycol. Or aromatic polyhydric alcohol etc., such as what added ethylene oxide to bisphenol, etc. are mentioned. Examples of the hydroxycarboxylic acid include glycolic acid and hydroxybutyric acid. Examples of the lactone include glycolide, ε-caprolactone, β-propiolactone, δ-butyrolactone, β- or γ-butyrolactone, pivalolactone, δ-valerolactone, and the like.

The weight average molecular weight of polylactic acid is preferably in the range of 100,000 to 500,000, more preferably 110,000 to 350,000, and still more preferably 120,000 to 250,000 in order to achieve both the mechanical properties and the modeling properties of the molded product. The weight average molecular weight is a value measured by gel permeation chromatography (GPC) and converted to standard polystyrene.
When polylactic acid is poly-D-lactic acid or poly-L-lactic acid and is homophase polylactic acid, it has a crystal melting peak (Tmh) between 150-190 ° C. by differential scanning calorimetry (DSC) measurement. The heat of crystal melting (ΔHmsc) is preferably 10 J / g or more. By satisfying the range of the crystal melting point and the crystal melting heat, the heat resistance of the shaped article can be enhanced.

Further, as the main chain of polylactic acid, stereocomplex polylactic acid containing a stereocomplex phase formed by poly L-lactic acid units and poly D-lactic acid units is also suitably employed.
Stereocomplex polylactic acid preferably exhibits a crystal melting peak of 190 ° C. or higher by differential scanning calorimetry (DSC) measurement.
The stereocomplex polylactic acid preferably has a stereocomplexation degree (S) defined by the following formula (i) of 90 to 100%.
S = [ΔHms / (ΔHmh + ΔHms)] × 100 (i)
(However, ΔHms represents the crystal melting enthalpy of stereocomplex phase polylactic acid, and ΔHmh represents the melting enthalpy of polylactic acid homophase crystal.)
The crystallinity of stereocomplex polylactic acid, particularly the crystallinity by XRD measurement, is preferably at least 5%, more preferably 5-60%, even more preferably 7-60%, particularly preferably 10-60%. is there.

The crystalline melting point of stereocomplex polylactic acid is preferably 190 to 250 ° C, more preferably 200 to 230 ° C. The crystal melting enthalpy by DSC measurement of stereocomplex polylactic acid is preferably 20 J / g or more, more preferably 20 to 80 J / g, still more preferably 30 to 80 J / g. When the crystalline melting point of stereocomplex polylactic acid is less than 190 ° C., the heat resistance is deteriorated. Moreover, when it exceeds 250 degreeC, it will be necessary to shape | mold at the high temperature of 250 degreeC or more, and it may become difficult to suppress thermal decomposition of resin. Therefore, it is preferable that stereocomplex polylactic acid shows a crystal melting peak of 190 ° C. or higher by differential scanning calorimetry (DSC) measurement.
In the stereocomplex polylactic acid, the weight ratio of poly D-lactic acid to poly L-lactic acid is preferably 90/10 to 10/90. More preferably, it is in the range of 80/20 to 20/80, more preferably 30/70 to 70/30, particularly preferably 40/60 to 60/40, and theoretically preferably as close to 1/1 as possible. .
The weight average molecular weight of the stereocomplex polylactic acid is preferably in the range of 50,000 to 500,000, more preferably 80,000 to 350,000, and still more preferably 120,000 to 250,000. The weight average molecular weight is a value measured by gel permeation chromatography (GPC) and converted to standard polystyrene.

Poly L-lactic acid and poly D-lactic acid can be produced by a conventionally known method. For example, it can be produced by ring-opening polymerization of L- or D-lactide in the presence of a metal-containing catalyst. In addition, low molecular weight polylactic acid containing a metal-containing catalyst is crystallized as desired or without crystallization, under reduced pressure or from normal pressure, in the presence of an inert gas stream, or absent It can also be produced by solid phase polymerization. Furthermore, it can be produced by a direct polymerization method in which lactic acid is subjected to dehydration condensation in the presence or absence of an organic solvent.
The polymerization reaction can be carried out in a conventionally known reaction vessel. For example, in a ring-opening polymerization or direct polymerization method, a vertical reactor or a horizontal reactor equipped with a stirring blade for high viscosity, such as a helical ribbon blade, is used alone, or Can be used in parallel. Moreover, any of a batch type, a continuous type, a semibatch type may be sufficient, and these may be combined.
Alcohol may be used as a polymerization initiator. Such alcohol is preferably non-volatile without inhibiting the polymerization of polylactic acid, such as decanol, dodecanol, tetradecanol, hexadecanol, octadecanol, ethylene glycol, trimethylolpropane, pentaerythritol, etc. Can be suitably used. It can be said that the polylactic acid prepolymer used in the solid-phase polymerization method is preferably crystallized in advance from the viewpoint of preventing resin pellet fusion. The prepolymer is in a solid state in a fixed vertical or horizontal reaction vessel, or in a reaction vessel (such as a rotary kiln) in which the vessel itself rotates, such as a tumbler or kiln, in the temperature range from the glass transition temperature of the prepolymer to less than the melting point. Polymerized.

Metal-containing catalysts include alkali metals, alkaline earth metals, rare earths, transition metals, fatty acid salts such as aluminum, germanium, tin, antimony, titanium, carbonates, sulfates, phosphates, oxides, hydroxides , Halides, alcoholates and the like. Among them, fatty acid salts, carbonates, sulfates, phosphates, oxides, hydroxides containing at least one metal selected from tin, aluminum, zinc, calcium, titanium, germanium, manganese, magnesium and rare earth elements Products, halides, and alcoholates are preferred.
Tin compounds due to low catalytic activity and side reactions, specifically stannous chloride, stannous bromide, stannous iodide, stannous sulfate, stannic oxide, tin myristate, tin octylate Tin-containing compounds such as tin stearate and tetraphenyltin are exemplified as preferred catalysts. Among these, tin (II) compounds, specifically, diethoxytin, dinonyloxytin, tin (II) myristate, tin (II) octylate, tin (II) stearate, tin (II) chloride and the like are suitable. Illustrated.
The amount of the catalyst used is 0.42 × 10 ^{−4 to} 100 × 10 ⁻⁴ (mole) per 1 kg of lactide, and 1.68 × 10 ^{−4 in} consideration of reactivity, color tone and stability of the resulting polylactides. To 42.1 × 10 ⁻⁴ (mol), particularly preferably 2.53 × 10 ^{−4 to} 16.8 × 10 ⁻⁴ (mol).

The metal-containing catalyst used for the polymerization of polylactic acid is preferably deactivated with a conventionally known deactivator prior to using polylactic acid. Examples of such a deactivator include an organic ligand having a group of chelate ligands having an imino group and capable of coordinating with a polymerized metal catalyst. Also, dihydridooxoline (I) acid, dihydridotetraoxodiphosphorus (II, II) acid, hydridotrioxoline (III) acid, dihydridopentaoxodiphosphoric acid (III), hydridopentaoxodi (II, IV) Acid, dodecaoxohexaphosphoric acid (III), hydridooctaoxotriphosphoric acid (III, IV, IV) acid, octaoxotriphosphoric acid (IV, III, IV) acid, hydridohexaoxodiphosphoric acid (III, V) acid, hexaoxodiacid Examples thereof include low oxidation number phosphoric acids having an acid number of 5 or less, such as phosphorus (IV) acid, decaoxotetralinic (IV) acid, hendecaoxotetraphosphoric (IV) acid, and eneoxooxophosphorus (V, IV, IV) acid. Further, orthophosphoric acid represented by the formula xH ₂ O · yP ₂ O ₅ and x / y = 3 may be mentioned. Moreover, polyphosphoric acid which is 2> x / y> 1, and is called diphosphoric acid, triphosphoric acid, tetraphosphoric acid, pentaphosphoric acid or the like based on the degree of condensation, and a mixture thereof can be mentioned. Moreover, the metaphosphoric acid represented by x / y = 1, especially trimetaphosphoric acid and tetrametaphosphoric acid are mentioned. Further, ultraphosphoric acid represented by 1> x / y> 0 and having a network structure in which a part of the phosphorus pentoxide structure is left (these may be collectively referred to as a metaphosphoric acid compound) may be mentioned. Moreover, the acid salt of these acids is mentioned. Moreover, the monovalent | monohydric and polyhydric alcohol of these acids, the partial ester of polyalkylene glycol, and complete ester are mentioned. Examples thereof include phosphono-substituted lower aliphatic carboxylic acid derivatives of these acids.

In view of the catalyst deactivation ability, orthophosphoric acid represented by the formula xH ₂ O · yP ₂ O ₅ and x / y = 3 is preferred. Moreover, 2> x / y> 1, and polyphosphoric acid referred to as diphosphoric acid, triphosphoric acid, tetraphosphoric acid, pentaphosphoric acid and the like, and a mixture thereof are preferable from the degree of condensation. Further, metaphosphoric acid represented by x / y = 1, particularly trimetaphosphoric acid and tetrametaphosphoric acid are preferable. Ultraphosphoric acid represented by 1> x / y> 0 and having a network structure in which a part of the phosphorus pentoxide structure is left (these may be collectively referred to as a metaphosphoric acid compound) is preferable. Moreover, the acidic salt of these acids is preferable. Further, monovalent or polyhydric alcohols of these acids or partial esters of polyalkylene glycols are preferred.

The metaphosphoric acid compound used in the present invention is a cyclic metaphosphoric acid in which about 3 to 200 phosphoric acid units are condensed, an ultra-region metaphosphoric acid having a three-dimensional network structure, or an alkali metal salt or an alkaline earth metal salt thereof. Onium salts). Among them, cyclic sodium metaphosphate, ultra-region sodium metaphosphate, phosphono-substituted lower aliphatic carboxylic acid derivative dihexylphosphonoethyl acetate (hereinafter sometimes abbreviated as DHPA) and the like are preferably used.
The polylactic acid preferably has a lactide content of 1 to 5000 ppm by weight. The lactide contained in the polylactic acid deteriorates the resin and deteriorates the color tone at the time of melt processing, and in some cases, it may be disabled as a product.
The poly L- and / or poly D-lactic acid immediately after the melt ring-opening polymerization usually contains 1 to 5% by weight of lactide, but the poly L- and / or poly D-lactic acid molding starts from the end of the polymerization. At any stage up to the above, a conventionally known lactide weight loss method, that is, a vacuum devolatilization method in a single or multi-screw extruder, or a high vacuum treatment in a polymerization apparatus is carried out alone or in combination. In addition, lactide can be reduced to a suitable range.

The smaller the lactide content, the better the melt stability and heat-and-moisture resistance of the resin, but there is also the advantage of lowering the resin melt viscosity, making it reasonable and economical to meet the desired purpose. is there. In other words, it is reasonable to set it to 1 to 1000 ppm by weight where practical melt stability is achieved. More preferably, a range of 1 to 700 ppm by weight, more preferably 2 to 500 ppm by weight, particularly preferably 5 to 100 ppm by weight is selected. By having a lactide content in such a range that the polylactic acid component is in this range, it is possible to improve the stability of the resin at the time of three-dimensional modeling of the molded product of the present invention, the advantage that the molded product can be efficiently manufactured, and the stability of the molded product against moisture and heat And low gas properties can be improved.
The stereocomplex polylactic acid is prepared by bringing poly L-lactic acid and poly D-lactic acid into contact in a weight ratio of 10/90 to 90/10, preferably by melt contact, and more preferably melt kneading. Can be obtained. The contact temperature is preferably 190 to 300 ° C, more preferably 200 to 290 ° C, and still more preferably 210 to 280 ° C, from the viewpoint of improving the stability of polylactic acid when melted and the degree of stereocomplex crystallinity.
The method of melt kneading is not particularly limited, but a conventionally known batch type or continuous type melt mixing apparatus is preferably used. For example, a melt-stirred tank, a single-screw or twin-screw extruder, a kneader, a non-shaft vertical stirrer, “Vibolac (registered trademark)” manufactured by Sumitomo Heavy Industries, Ltd., N-SCR manufactured by Mitsubishi Heavy Industries, Ltd. ( Glasses blades, lattice blades or Kenix type stirrers made by Hitachi, Ltd., or Sulzer type SMLX type static mixer equipped pipe type polymerization equipment can be used. A non-axial vertical stirring tank, an N-SCR, a twin-screw extruder, or the like that is a polymerization apparatus is preferably used.

In the polylactic acid used in the present invention, a method of blending a specific additive in order to stably and highly promote the formation of stereocomplex polylactic acid crystals is preferably applied without departing from the gist of the present invention. The additive is not particularly limited as long as it has a transesterification catalytic ability. Among them, organic acid metal salts are preferably used, and examples thereof include known phosphoric acid metal salts, carboxylic acid metal salts, and sulfonic acid metal salts.
The polymer material of the present invention preferably has a small molecular weight change rate under heating conditions. When the weight average molecular weight of the polymer material of the present invention is Mw ₁ and the weight average molecular weight after the heating test is Mw ₂ , the molecular weight change rate is represented by the following formula (ii).
Molecular weight change rate (%) = [(Mw ₂ −Mw ₁ ) / Mw ₁ ] × 100 (ii)
Here, Mw ₁ and Mw ₂ are values measured by gel permeation chromatography (GPC) and converted to standard polystyrene. The molecular weight may be evaluated by the solution viscosity method or other methods when evaluation by GPC is difficult. In addition, when gelation occurs after wet heat treatment and it becomes difficult to evaluate the molecular weight, the molecular weight change rate is regarded as a plus infinity value.

In melt deposition modeling using a thermoplastic polymer material, when using a melt deposition modeling apparatus equipped with a plurality of ejection heads and stacking a plurality of different materials at the same time, the ejection head waiting for ejection is heated. Therefore, it is preferable that the change in physical properties under heating conditions is small. As an indicator of such a change in physical properties over time, in particular, a change in physical properties due to hydrolysis, a change in molecular weight under wet heat conditions of 80 ° C. and 95% RH (relative humidity) can be employed. When the molecular weight of the three-dimensional modeling material changes, the fluidity of the material heated by the ejection head changes as described below. If the molecular weight is too low, the fluidity becomes excessive, and dripping of the material and disturbance of the supply speed occur. On the other hand, if the molecular weight is too high, the fluidity is too low, and the discharge amount is reduced and the discharge head is clogged. From this viewpoint, the molecular weight change rate after treatment for 12 hours at 80 ° C. and 95% RH is preferably −50% or more, more preferably −20% or more, further preferably −10% or more, and −10% or more plus 100% or less is more preferable. By satisfying this characteristic, the physical properties of the polymer material during storage and modeling can be stabilized, and modeling can be performed stably.
Moreover, as long as the polylactic acid resin to be used is within the range not impairing the effects of the present invention, generally used matting agents such as titanium oxide and calcium carbonate, lubricants, antioxidants, heat resistance agents, heat resistance agents, light resistance, Agents, ultraviolet absorbers, antistatic agents, flame retardants, and the like.

<Shape of polylactic acid strand>
In the present invention, the polylactic acid strand refers to a polymer material containing polylactic acid as a main component formed into a strand shape, that is, a fiber shape having a diameter of approximately 1 mm or more. The average value of the diameter of the strand is 1.0 to 3.5 mm. Polylactic acid strands with diameters in this range are likely to have moderate flexibility and rigidity, and when used for melt deposition modeling, there are abnormalities due to breakage or buckling in the process from the strand feed mechanism to the discharge head. It is preferable because it hardly occurs.
From the viewpoint of achieving that the polymer material is supplied to the discharge head at a desired volume speed when the strand feed rate (linear velocity in the length direction) is controlled by a strand feed mechanism such as a roller, The diameter is preferably stable. Specifically, the diameter variation rate is preferably 5% or less, more preferably 3% or less, further preferably 2% or less, and most preferably 1% or less.

  The strand-shaped polylactic acid supplied to the discharge head is in a solid state on the upstream side and in a molten liquid state on the downstream side (nozzle outlet side of the discharge head), and the solid on the upstream side is downstream like a piston. The molten resin is ejected from the ejection head by extruding the molten liquid. In order for the supplied solid strands to always function as a piston, it is necessary that the strands have a sufficient length and that their outer diameter is not too small compared to the inner diameter of the discharge head. On the other hand, it is indispensable to prevent the strands from clogging in the discharge head that the strand has a sufficient length and that the outer diameter is not larger than the inner diameter of the discharge head. From the above viewpoint, it is preferable that the fluctuation range of the diameter of the strand is small. Specifically, the diameter fluctuation range is 15% or less, preferably 12% or less, more preferably 9% or less, and even more preferably 7% or less.

The average value, variation rate, and variation range of the diameter are measured by the following methods. The outer diameter is measured while scanning the strand at a constant speed with a laser type outer diameter measuring device (for example, LS-9000 manufactured by Keyence Corporation) having a measurement accuracy of ± 5 μm or more. A moving average value of data of 8 or more points measured during a length shorter than 50 mm is taken as one measurement value, and 1000 measurement values are sampled at an interval of 50 mm / point. From the average value (D) of the sampled 1000 strand outer diameters, the standard deviation (σ) of the outer diameter, the maximum value of the outer diameter (D _Max ), and the minimum value of the outer diameter (D _Min ), the following formula (iii) -1) and (iii-2), the average value, variation rate, and variation range of the strand diameter are calculated.
Diameter variation rate (%) = σ / D × 100 (iii-1)
Diameter fluctuation range (%) = (D _Max −D _Min ) / D × 100 (iii-2)
σ: Standard deviation of outer diameter D: Average value of outer diameter (mm)
D _Max : Maximum outer diameter D _Min : Minimum outer diameter

<Shrinkage of polylactic acid strand>
The polylactic acid strand of the present invention has a thermal shrinkage rate of 10% or more when immersed for 1 minute in silicone oil held at the melting point of the sample. In general, when a layered structure such as a bridge is formed in a melt layered modeling using a thermoplastic polymer material, a situation occurs in which the lower layer of the place where the molten resin is discharged from the discharge head is hollow as shown in FIG. However, the polylactic acid strand of the present invention contains a semi-molten resin at the time of melting and discharging, and the thermal contraction action prevents the drooping.

  Furthermore, generally in melt layered modeling using thermoplastic polymer materials, when stopping discharge at a portion where discharge is not required during modeling, discharge is possible even if the strand feed rate is set to zero or the strand is pulled back to minus. Due to the residual pressure of the resin pushed into the tip of the head, excess resin may be ejected and a three-dimensional model with a desired shape may not be obtained. Since the shrinkage starts when heated, the residual pressure at the tip of the discharge head can be instantly canceled and the discharge of excess resin can be reduced at the same time as the strand feeding is stopped or pulled back. It becomes easy to obtain a model with high dimensional accuracy. From this point of view, the thermal shrinkage when immersed for 1 minute in oil held at the melting point of the polylactic acid strand sample is preferably 5% or more, more preferably 10% or more, and more preferably 20% or more. Is more preferable.

The measurement of heat shrinkage is tested by the following method. A polylactic acid strand sample is cut to a length of 150 mm, and a marked line is attached to a portion 100 mm from one end (referred to as end A). The other end (referred to as end B) is held with tweezers, and immersed in silicone oil maintained at the melting point of the polylactic acid strand sample so that the portion from end A to the marked line is sufficiently immersed in the silicone oil. After immersion for 1 minute, the silicone oil is taken out, wiped with excess oil, cooled to room temperature, the length from the end A to the marked line is measured, and is defined as Lmm. The thermal contraction rate is calculated according to the equation (iv).
Thermal contraction rate (%) = 100−L (iv)
A sample subjected to heat shrinkage measurement is a sample after heat setting at 110 ° C. for 1 hour in order to accurately measure the melting point. The heat setting is performed with both ends of the polylactic acid strand fixed. The melting point for determining the temperature of the silicone oil in the heat shrink test is 130 ° C. or higher in a temperature rising DSC (differential scanning calorimetry) spectrum measured at a temperature rising rate of 20 ° C./min from 30 ° C. to 250 ° C. Among the endothermic peaks, the peak temperature of the peak with the highest peak intensity is defined as the melting point.

<Crystalline of polylactic acid strand>
In the polylactic acid strand of the present invention, a portion having a thickness of (diameter / 4) satisfies the following A from the surface of the strand.
A: In the spectrum analyzed by the temperature rise DSC, the temperature at the top of the crystal melting peak is 140 ° C. or higher, the calorie of the melting peak is 30 J / g or higher, and the half width of the melting peak is 20 ° C. or lower.
In melt additive manufacturing using polylactic acid strands, the strands inside the discharge head are heated above the melting point of polylactic acid so that they have sufficient fluidity near the discharge port and approach normal temperature as they move away from the discharge port. Therefore, the resin has fluidity (viscoelasticity) distribution according to the strand temperature at each location. That is, the portion close to the discharge port has a relatively high fluidity as a molten liquid, the portion sufficiently away from the discharge port has no fluidity as a solid, and the portion in between is derived from an amorphous part of polylactic acid. It will have rubber-like viscoelasticity. On the other hand, when stopping discharge at a portion where discharge is not required during modeling, the strand feed speed is made zero or pulled back to a negative, and the solid strand in the discharge head acts as a piston. Thus, the discharge amount is controlled. At this time, if a resin having rubber-like viscoelasticity is present in the discharge head, the solid strand feeding / stopping operation is mitigated by the rubber-like resin, so that the molten resin can be discharged / discharged from the discharge port. As a result of the delay in stopping, a three-dimensional model having a desired shape may not be obtained.

On the other hand, when a polylactic acid strand having a high crystal melting heat amount and a sharp melting peak in the temperature-enhanced DSC spectrum is supplied to the discharge head and heated, it takes a sufficiently hard solid state below the melting start temperature, and the melting start temperature is reduced. If the temperature exceeds the range, the molten liquid having a good fluidity is quickly taken, and the temperature range for taking the rubber-like viscoelastic body causing the above problems is small. Therefore, the solid strand feeding / stopping operation is well transmitted to the molten resin at the discharge port, so that it becomes easy to obtain a three-dimensional model having a desired shape with high dimensional accuracy.
In addition, in order for the strand to play a role as a sufficiently hard piston, the shape of the entire strand can be obtained if the thickness (diameter / 4) from the surface (side surface of the cylinder) is sufficiently hard. The change is sufficiently suppressed, and the above effects are sufficiently exhibited.

  From this point of view, in the spectrum obtained by surface DSC analysis of the portion having a thickness of (diameter / 4) from the surface of the polylactic acid strand, the calorific value of the melting peak is preferably 5 J / g, more preferably 10 J / g or more, and 20 J / g. The above is more preferable, 30 J / g or more is more preferable, and 40 J / g or more is most preferable. Further, the half width of the melting peak is preferably 30 ° C. or less, more preferably 20 ° C. or less, and further preferably 10 ° C. or less. In addition, the degree of crystallinity derived from polylactic acid measured by wide-angle X-ray diffraction analysis (WAXD) from the surface of the polylactic acid strand (diameter / 4) is preferably 10% or more, more preferably 15% or more. Preferably, 20% or more is more preferable. Here, the crystallinity derived from polylactic acid is the sum of the crystallinity derived from homopoly L-lactic acid and poly D-lactic acid and the crystallinity derived from stereocomplex polylactic acid.

  In the present invention, the temperature-rising DSC analysis of the portion having a thickness of (diameter / 4) from the surface of the polylactic acid strand is performed as follows. Sampling uses a precision nipper, cuts the polylactic acid strand to a length of 1 mm, and cuts the side surface (a portion having a thickness of (diameter / 4) from the outer circumference of the circle) once into a comb to obtain a sample piece. This is repeated at any point of the polylactic acid strand, and a total of 5 mg sample pieces are used for DSC measurement. Sampling may be performed by other similar methods. The sample is sealed in an aluminum seal cell and subjected to temperature rising DSC analysis from 30 ° C. to 250 ° C. at a temperature rising rate of 20 ° C./min. Of the endothermic peaks at 130 ° C. or higher in the obtained DSC spectrum, the peak with the highest peak intensity is taken as the melting peak. The melting point is the temperature at the peak of the melting peak.

<End sealant>
The polylactic acid used for the production of the polylactic acid strand is preferably added with an end-capping agent, that is, an agent that seals acidic end groups of the polymer material and acidic groups generated by decomposition. Polylactic acid is hydrolyzed by autocatalysis of acidic groups derived from its structure, but end-capping agents are agents that have the effect of suppressing this autocatalysis and delaying hydrolysis.
As the end-capping agent, an epoxy compound or a carbodiimide compound is preferably used, and a carbodiimide compound is more preferably used because it can react with a carboxyl terminal group quickly and selectively.
In addition, as the end-capping agent, volatilization of the liberated isocyanate compound is suppressed, the viewpoint of maintaining a good modeling work environment, and gasification of the liberated isocyanate compound causes bubbles to be mixed into the shaped product and the appearance of the shaped product The cyclic carbodiimide compound described later is more preferably used from the viewpoint of eliminating the possibility of impairing the quality.

<Cyclic carbodiimide compound>
The cyclic carbodiimide compound has a cyclic structure. The cyclic carbodiimide compound may have a plurality of cyclic structures.
The cyclic structure has one carbodiimide group (—N═C═N—), and the first nitrogen and the second nitrogen are bonded by a bonding group. One cyclic structure has only one carbodiimide group. The number of atoms in the cyclic structure is preferably 8 to 50, more preferably 10 to 30, and still more preferably 10 to 20.
Here, the number of atoms in the ring structure means the number of atoms that directly constitute the ring structure, and is, for example, 8 for an 8-membered ring and 50 for a 50-membered ring. This is because if the number of atoms in the cyclic structure is smaller than 8, the stability of the cyclic carbodiimide compound is lowered, and it may be difficult to store and use. From the viewpoint of reactivity, there is no particular restriction on the upper limit of the number of ring members, but cyclic carbodiimide compounds having more than 50 atoms are difficult to synthesize, and the cost may increase significantly. From this viewpoint, the number of atoms in the cyclic structure is preferably selected in the range of 10-30, more preferably 10-20.
The cyclic structure is preferably a structure represented by the following formula (2).

(In the formula, Q is a divalent to tetravalent linking group that is an aliphatic group, an alicyclic group, an aromatic group, or a combination thereof, and may contain a hetero atom.)
In the formula, Q is a divalent to tetravalent linking group that is an aliphatic group, an alicyclic group, an aromatic group, or a combination thereof, each of which may contain a hetero atom and a substituent. A heteroatom in this case refers to O, N, S, P. Two of the valences of this linking group are used to form a cyclic structure. When Q is a trivalent or tetravalent linking group, it is bonded to a polymer or other cyclic structure via a single bond, a double bond, an atom, or an atomic group.
The linking group may include a heteroatom and a substituent, each having a divalent to tetravalent carbon number of 1 to 20 aliphatic group, a divalent to tetravalent carbon number of 3 to 20 alicyclic group, A linking group which is a tetravalent aromatic group having 5 to 15 carbon atoms or a combination thereof and has a necessary number of carbon atoms to form the cyclic structure defined above is selected. Examples of combinations include structures such as an alkylene-arylene group in which an alkylene group and an arylene group are bonded.

  The linking group (Q) is preferably a divalent to tetravalent linking group represented by the following formula (3-1), (3-2) or (3-3).

In the formula, Ar ¹ and Ar ² are each independently a 2- to 4-valent aromatic group having 5 to 15 carbon atoms which may contain a hetero atom and a substituent.

As an aromatic group, each of which contains a hetero atom and may have a heterocyclic structure, an arylene group having 5 to 15 carbon atoms, an arenetriyl group having 5 to 15 carbon atoms, an arenetetra having 5 to 15 carbon atoms Yl group. Examples of the arylene group (divalent) include a phenylene group and a naphthalenediyl group. Examples of the arenetriyl group (trivalent) include a benzenetriyl group and a naphthalenetriyl group. Examples of the arenetetrayl group (tetravalent) include a benzenetetrayl group and a naphthalenetetrayl group. These aromatic groups may be substituted. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.
R ¹ and R ² each independently contain a heteroatom and a substituent, each having 2 to 4 valent aliphatic groups having 1 to 20 carbon atoms and 2 to 4 valent fatty acids having 3 to 20 carbon atoms A cyclic group, and a combination thereof, or a combination of the aliphatic group, the alicyclic group, and a divalent to tetravalent aromatic group having 5 to 15 carbon atoms.

  Examples of the aliphatic group include an alkylene group having 1 to 20 carbon atoms, an alkanetriyl group having 1 to 20 carbon atoms, and an alkanetetrayl group having 1 to 20 carbon atoms. Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, a dodecylene group, and a hexadecylene group. As the alkanetriyl group, methanetriyl group, ethanetriyl group, propanetriyl group, butanetriyl group, pentanetriyl group, hexanetriyl group, heptanetriyl group, octanetriyl group, nonanetriyl group, decantriyl group, dodecantriyl group, Examples include a hexadecantriyl group. As alkanetetrayl group, methanetetrayl group, ethanetetrayl group, propanetetrayl group, butanetetrayl group, pentanetetrayl group, hexanetetrayl group, heptanetetrayl group, octanetetrayl group, nonanetetrayl group Decanetetrayl group, dodecanetetrayl group, hexadecanetetrayl group and the like. These aliphatic groups may be substituted. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.

  Examples of the alicyclic group include a cycloalkylene group having 3 to 20 carbon atoms, a cycloalkanetriyl group having 3 to 20 carbon atoms, and a cycloalkanetetrayl group having 3 to 20 carbon atoms. Examples of the cycloalkylene group include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclononylene group, a cyclodecylene group, a cyclododecylene group, and a cyclohexadecylene group. As cycloalkanetriyl group, cyclopropanetriyl group, cyclobutanetriyl group, cyclopentanetriyl group, cyclohexanetriyl group, cycloheptanetriyl group, cyclooctanetriyl group, cyclononanetriyl group, cyclodecanetriyl group Group, cyclododecane triyl group, cyclohexadecane triyl group and the like. As cycloalkanetetrayl group, cyclopropanetetrayl group, cyclobutanetetrayl group, cyclopentanetetrayl group, cyclohexanetetrayl group, cycloheptanetetrayl group, cyclooctanetetrayl group, cyclononanetetrayl group, cyclodecanetetrayl group Yl group, cyclododecanetetrayl group, cyclohexadecanetetrayl group and the like. These alicyclic groups may be substituted. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.

As an aromatic group, each of which contains a hetero atom and may have a heterocyclic structure, an arylene group having 5 to 15 carbon atoms, an arenetriyl group having 5 to 15 carbon atoms, an arenetetra having 5 to 15 carbon atoms Yl group. Examples of the arylene group include a phenylene group and a naphthalenediyl group. Examples of the arenetriyl group (trivalent) include a benzenetriyl group and a naphthalenetriyl group. Examples of the arenetetrayl group (tetravalent) include a benzenetetrayl group and a naphthalenetetrayl group. These aromatic groups may be substituted. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.
X ¹ and X ² each independently contain a heteroatom and a substituent, each having a 2 to 4 valent aliphatic group having 1 to 20 carbon atoms and a 2 to 4 valent fatty acid having 3 to 20 carbon atoms It is a cyclic group, a divalent to tetravalent aromatic group having 5 to 15 carbon atoms, or a combination thereof.

  Examples of the aliphatic group include an alkylene group having 1 to 20 carbon atoms, an alkanetriyl group having 1 to 20 carbon atoms, and an alkanetetrayl group having 1 to 20 carbon atoms. Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, a dodecylene group, and a hexadecylene group. As the alkanetriyl group, methanetriyl group, ethanetriyl group, propanetriyl group, butanetriyl group, pentanetriyl group, hexanetriyl group, heptanetriyl group, octanetriyl group, nonanetriyl group, decantriyl group, dodecantriyl group, Examples include a hexadecantriyl group. As alkanetetrayl group, methanetetrayl group, ethanetetrayl group, propanetetrayl group, butanetetrayl group, pentanetetrayl group, hexanetetrayl group, heptanetetrayl group, octanetetrayl group, nonanetetrayl group Decanetetrayl group, dodecanetetrayl group, hexadecanetetrayl group and the like. These aliphatic groups may be substituted. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.

  Examples of the alicyclic group include a cycloalkylene group having 3 to 20 carbon atoms, a cycloalkanetriyl group having 3 to 20 carbon atoms, and a cycloalkanetetrayl group having 3 to 20 carbon atoms. Examples of the cycloalkylene group include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclononylene group, a cyclodecylene group, a cyclododecylene group, and a cyclohexadecylene group. As the alkanetriyl group, cyclopropanetriyl group, cyclobutanetriyl group, cyclopentanetriyl group, cyclohexanetriyl group, cycloheptanetriyl group, cyclooctanetriyl group, cyclononanetriyl group, cyclodecanetriyl group , Cyclododecanetriyl group, cyclohexadecanetriyl group and the like. As the alkanetetrayl group, cyclopropanetetrayl group, cyclobutanetetrayl group, cyclopentanetetrayl group, cyclohexanetetrayl group, cycloheptanetetrayl group, cyclooctanetetrayl group, cyclononanetetrayl group, cyclodecanetetrayl group Group, cyclododecanetetrayl group, cyclohexadecanetetrayl group and the like. These alicyclic groups may be substituted. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.

  As an aromatic group, each of which contains a hetero atom and may have a heterocyclic structure, an arylene group having 5 to 15 carbon atoms, an arenetriyl group having 5 to 15 carbon atoms, an arenetetra having 5 to 15 carbon atoms Yl group. Examples of the arylene group include a phenylene group and a naphthalenediyl group. Examples of the arenetriyl group (trivalent) include a benzenetriyl group and a naphthalenetriyl group. Examples of the arenetetrayl group (tetravalent) include a benzenetetrayl group and a naphthalenetetrayl group. These aromatic groups may be substituted. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.

In formulas (3-1) and (3-2), s and k are integers of 0 to 10, preferably 0 to 3, more preferably 0 to 1. When s and k exceed 10, the cyclic carbodiimide compound is difficult to synthesize, and the cost may increase significantly. From this viewpoint, the integer is preferably selected in the range of 0 to 3. When s or k is 2 or more, X ¹ or X ² as a repeating unit may be different from other X ¹ or X ² .
X ³ is a divalent to tetravalent C 1-20 aliphatic group, a divalent to tetravalent C 3-20 alicyclic group, each of which may contain a heteroatom and a substituent, A tetravalent aromatic group having 5 to 15 carbon atoms, or a combination thereof.

Examples of the aliphatic group include an alkylene group having 1 to 20 carbon atoms, an alkanetriyl group having 1 to 20 carbon atoms, and an alkanetetrayl group having 1 to 20 carbon atoms. Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, a nonylene group, a decylene group, a dodecylene group, and a hexadecylene group. As the alkanetriyl group, methanetriyl group, ethanetriyl group, propanetriyl group, butanetriyl group, pentanetriyl group, hexanetriyl group, heptanetriyl group, octanetriyl group, nonanetriyl group, decantriyl group, dodecantriyl group, Examples include a hexadecantriyl group. As alkanetetrayl group, methanetetrayl group, ethanetetrayl group, propanetetrayl group, butanetetrayl group, pentanetetrayl group, hexanetetrayl group, heptanetetrayl group, octanetetrayl group, nonanetetrayl group Decanetetrayl group, dodecanetetrayl group, hexadecanetetrayl group and the like. These aliphatic groups may contain a substituent, such as an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, or an ester group. , Ether group, aldehyde group and the like.

  Examples of the alicyclic group include a cycloalkylene group having 3 to 20 carbon atoms, a cycloalkanetriyl group having 3 to 20 carbon atoms, and a cycloalkanetetrayl group having 3 to 20 carbon atoms. Examples of the cycloalkylene group include a cyclopropylene group, a cyclobutylene group, a cyclopentylene group, a cyclohexylene group, a cycloheptylene group, a cyclooctylene group, a cyclononylene group, a cyclodecylene group, a cyclododecylene group, and a cyclohexadecylene group. As the alkanetriyl group, cyclopropanetriyl group, cyclobutanetriyl group, cyclopentanetriyl group, cyclohexanetriyl group, cycloheptanetriyl group, cyclooctanetriyl group, cyclononanetriyl group, cyclodecanetriyl group , Cyclododecanetriyl group, cyclohexadecanetriyl group and the like. As the alkanetetrayl group, cyclopropanetetrayl group, cyclobutanetetrayl group, cyclopentanetetrayl group, cyclohexanetetrayl group, cycloheptanetetrayl group, cyclooctanetetrayl group, cyclononanetetrayl group, cyclodecanetetrayl group Group, cyclododecanetetrayl group, cyclohexadecanetetrayl group and the like. These alicyclic groups may contain a substituent, such as an alkyl group having 1 to 20 carbon atoms, an arylene group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, and an ester. Group, ether group, aldehyde group and the like.

  As an aromatic group, each of which contains a hetero atom and may have a heterocyclic structure, an arylene group having 5 to 15 carbon atoms, an arenetriyl group having 5 to 15 carbon atoms, an arenetetra having 5 to 15 carbon atoms Yl group. Examples of the arylene group include a phenylene group and a naphthalenediyl group. Examples of the arenetriyl group (trivalent) include a benzenetriyl group and a naphthalenetriyl group. Examples of the arenetetrayl group (tetravalent) include a benzenetetrayl group and a naphthalenetetrayl group. These aromatic groups may be substituted. Examples of the substituent include an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 15 carbon atoms, a halogen atom, a nitro group, an amide group, a hydroxyl group, an ester group, an ether group, and an aldehyde group.

Ar ¹ , Ar ² , R ¹ , R ² , X ¹ , X ² and X ³ may contain a hetero atom, and when Q is a divalent linking group, Ar ¹ , Ar ² , R ¹ , R ² , X ¹ , X ² and X ³ are all divalent groups. When Q is a trivalent linking group, one of Ar ¹ , Ar ² , R ¹ , R ² , X ¹ , X ² and X ³ is a trivalent group. When Q is a tetravalent linking group, one of Ar ¹ , Ar ² , R ¹ , R ² , X ¹ , X ² and X ³ is a tetravalent group or two are trivalent It is a group.

  When cyclic carbodiimide is added to the material of the present invention, it contains end-capped polylactic acid having a structure in which the cyclic carbodiimide compound of the end-capping agent is bonded to the end of the polymer material. The cyclic carbodiimide compound reacts with the carboxyl group of the polymer material as follows to form a structure represented by the following (4) at the terminal of the polymer material.

(X is the main chain of the polymer material, and Q is a linking group that connects the first nitrogen and the second nitrogen of the carbodiimide group.)
Polylactic acid to which cyclic carbodiimide is added can be produced by mixing polylactic acid and a cyclic carbodiimide compound. The cyclic carbodiimide compound reacts with the terminal of polylactic acid to seal the terminal. Excess cyclic carbodiimide compound remains unreacted in the material.

Therefore, the polylactic acid to which the cyclic carbodiimide is added contains polylactic acid with a terminal capped and a cyclic carbodiimide compound. Further, depending on the degree of reaction of terminal modification, a polymer material whose terminal is not sealed may be contained.
The content of the cyclic carbodiimide compound remaining in the material unreacted is 0.001 to 10 parts by weight, preferably 0.01 to 5 parts by weight, more preferably 0.1 to 1 part per 100 parts by weight of polylactic acid. Parts by weight. If the amount is less than 0.001 part by weight, the effect of inhibiting hydrolysis may not be exhibited continuously. When the amount is excessively more than 10 parts by weight, gelation of the polymer material proceeds, and the fluidity and fusing property during heating may be impaired.

<Stabilizer>
The material used for producing the polylactic acid strand can contain a stabilizer. As a stabilizer, what is used for the stabilizer of a normal thermoplastic resin can be used. For example, an antioxidant, a light stabilizer, etc. can be mentioned. By blending these agents, a molded product having excellent mechanical properties, moldability, heat resistance and durability can be obtained.
Examples of the antioxidant include hindered phenol compounds, hindered amine compounds, phosphite compounds, thioether compounds, and the like.

  Examples of hindered phenol compounds include n-octadecyl-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) -propionate, n-octadecyl-3- (3′-methyl-5 ′). -Tert-butyl-4'-hydroxyphenyl) -propionate, n-tetradecyl-3- (3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) -propionate, 1,6-hexanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate], 1,4-butanediol-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) -Propionate], 2,2'-methylene-bis (4-methyl-tert-butylphenol), triethylene glycol-bis 3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate], tetrakis [methylene-3- (3 ′, 5′-di-tert-butyl-4-hydroxyphenyl) propionate] methane, 3,9-bis [2- {3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] 2,4,8,10-tetraoxaspiro ( 5,5) Undecane and the like can be mentioned.

  As a hindered amine compound, N, N′-bis-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionylhexamethylenediamine, N, N′-tetramethylene-bis [3- (3′-Methyl-5′-tert-butyl-4′-hydroxyphenyl) propionyl] diamine, N, N′-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionyl ] Hydrazine, N-salicyloyl-N'-salicylidenehydrazine, 3- (N-salicyloyl) amino-1,2,4-triazole, N, N'-bis [2- {3- (3,5-di -Tert-butyl-4-hydroxyphenyl) propionyloxy} ethyl] oxyamide and the like. Preferably, triethylene glycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) -propionate] and tetrakis [methylene-3- (3 ′, 5′-di-tert-butyl) -4-hydroxyphenyl) propionate] methane and the like.

  As the phosphite compound, those in which at least one P—O bond is bonded to an aromatic group are preferable. Specifically, tris (2,6-di-tert-butylphenyl) phosphite, tetrakis ( 2,6-di-tert-butylphenyl) 4,4′-biphenylene phosphite, bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol di-phosphite, 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl phosphite, 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecyl) phosphite, 1,1,3-tris (2-methyl-4-ditridecyl phosphite-5-tert-butylphenyl) butane, tris (mixed mono and di-no Butylphenyl) phosphite, tris (nonylphenyl) phosphite, 4,4'-isopropylidene-bis (phenyl - dialkyl phosphite), and the like.

  Among them, tris (2,6-di-tert-butylphenyl) phosphite, 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl phosphite, bis (2,6-di-tert-butyl) -4-Methylphenyl) pentaerythritol-diphosphite, tetrakis (2,6-di-tert-butylphenyl) 4,4′-biphenylene phosphite and the like can be preferably used.

  Specific examples of thioether compounds include dilauryl thiodipropionate, ditridecyl thiodipropionate, dimyristyl thiodipropionate, distearyl thiodipropionate, pentaerythritol-tetrakis (3-lauryl thiopropionate), Pentaerythritol-tetrakis (3-dodecylthiopropionate), pentaerythritol-tetrakis (3-octadecylthiopropionate), pentaerythritol tetrakis (3-myristylthiopropionate), pentaerythritol-tetrakis (3-stearylthio) Propionate) and the like.

Specific examples of the light stabilizer include benzophenone compounds, benzotriazole compounds, aromatic benzoate compounds, oxalic acid anilide compounds, cyanoacrylate compounds, hindered amine compounds, and the like.
Examples of the benzophenone compounds include benzophenone, 2,4-dihydroxybenzophenone, 2,2′-dihydroxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2 ′. -Dihydroxy-4,4'-dimethoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxy-5-sulfobenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 5-chloro-2-hydroxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-methoxy -2'-carbo Shi benzophenone, 2-hydroxy-4- (2-hydroxy-3-methyl - acryloxy-isopropoxyphenyl) benzophenone.

  Examples of the benzotriazole compound include 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- (3,5-di-tert-butyl-2-hydroxyphenyl) benzotriazole, 2- (3,5- Di-tert-amyl-2-hydroxyphenyl) benzotriazole, 2- (3 ′, 5′-di-tert-butyl-4′-methyl-2′-hydroxyphenyl) benzotriazole, 2- (3,5- Di-tert-amyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (5-tert-butyl-2-hydroxyphenyl) benzotriazole, 2- [2′-hydroxy-3 ′, 5′-bis (Α, α-Dimethylbenzyl) phenyl] benzotriazole, 2- [2′-hydroxy-3 ′, 5′-bis (α, α Dimethylbenzyl) phenyl] -2H- benzotriazole, 2- (4'-octoxy-2'-hydroxyphenyl) benzotriazole.

Examples of the aromatic benzoate compounds include alkylphenyl salicylates such as p-tert-butylphenyl salicylate and p-octylphenyl salicylate.
Examples of oxalic acid anilide compounds include 2-ethoxy-2′-ethyloxalic acid bisanilide, 2-ethoxy-5-tert-butyl-2′-ethyloxalic acid bisanilide, and 2-ethoxy-3′-. Examples include dodecyl oxalic acid bisanilide.
Examples of the cyanoacrylate compound include ethyl-2-cyano-3,3′-diphenyl acrylate and 2-ethylhexyl-cyano-3,3′-diphenyl acrylate.

  Examples of hindered amine compounds include 4-acetoxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-2,2,6, 6-tetramethylpiperidine, 4- (phenylacetoxy) -2,2,6,6-tetramethylpiperidine, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine, 4-methoxy-2,2, 6,6-tetramethylpiperidine, 4-octadecyloxy-2,2,6,6-tetramethylpiperidine, 4-cyclohexyloxy-2,2,6,6-tetramethylpiperidine, 4-benzyloxy-2,2 , 6,6-tetramethylpiperidine, 4-phenoxy-2,2,6,6-tetramethylpiperidine, 4- (ethylcarba Yloxy) -2,2,6,6-tetramethylpiperidine, 4- (cyclohexylcarbamoyloxy) -2,2,6,6-tetramethylpiperidine, 4- (phenylcarbamoyloxy) -2,2,6,6 -Tetramethylpiperidine, bis (2,2,6,6-tetramethyl-4-piperidyl) carbonate, bis (2,2,6,6-tetramethyl-4-piperidyl) oxalate, bis (2,2,6 , 6-tetramethyl-4-piperidyl) malonate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (2,2,6,6-tetramethylpi-4-peridyl) adipate, bis (2,2,6,6-tetramethylpi-4-peridyl) terephthalate, 1,2-bis (2,2,6,6-tetramethylpi-4-peridylo) Cis) -ethane, α, α′-bis (2,2,6,6-tetramethyl-4-piperidyloxy) -p-xylene, bis (2,2,6,6-tetramethyl-4-piperidyl) -Tolylene-2,4-dicarbamate, bis (2,2,6,6-tetramethyl-4-piperidyl) -hexamethylene-1,6-dicarbamate, tris (2,2,6,6-tetramethyl -4-piperidyl) -benzene-1,3,5-tricarboxylate, tris (2,2,6,6-tetramethyl-4-piperidyl) -benzene-1,3,4-tricarboxylate, 1- “2- {3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy} -2,2,6,6-tetramethylpiperidine, 1,2,3,4-butanetetracarboxylic acid And 1,2,2, , 6-Pentamethyl-4-piperidinol and β, β, β ′, β′-tetramethyl-3,9- [2,4,8,10-tetraoxaspiro (5,5) undecane] dimethanol And the like. In this invention, E component may be used by 1 type and may be used in combination of 2 or more type. As the stabilizer component, a hindered phenol compound and / or a benzotriazole compound are preferable. The content of the stabilizer is preferably 0.01 to 3 parts by weight, more preferably 0.03 to 2 parts by weight, per 100 parts by weight of polylactic acid.

<Crystallization accelerator>
The material used for producing the polylactic acid strand can contain an organic or inorganic crystallization accelerator. By containing the crystallization accelerator, a molded product having excellent mechanical properties, heat resistance, and moldability can be obtained.
That is, by applying the crystallization accelerator, moldability and crystallinity are improved, and a molded product that is sufficiently crystallized even in normal injection molding and excellent in heat resistance and moist heat resistance can be obtained. In addition, the manufacturing time for manufacturing the molded product can be greatly shortened, and the economic effect is great.

As the crystallization accelerator used in the present invention, those generally used as crystallization nucleating agents for crystalline resins can be used, and both inorganic crystallization nucleating agents and organic crystallization nucleating agents are used. be able to.
As inorganic crystallization nucleating agents, talc, kaolin, silica, synthetic mica, clay, zeolite, graphite, carbon black, zinc oxide, magnesium oxide, titanium oxide, calcium carbonate, calcium sulfate, barium sulfate, calcium sulfide, boron nitride , Montmorillonite, neodymium oxide, aluminum oxide, phenylphosphonate metal salt and the like. These inorganic crystallization nucleating agents are treated with various dispersing aids in order to enhance the dispersibility in the composition and the effect thereof, and are in a highly dispersed state with a primary particle size of about 0.01 to 0.5 μm. Are preferred.

  Organic crystallization nucleating agents include calcium benzoate, sodium benzoate, lithium benzoate, potassium benzoate, magnesium benzoate, barium benzoate, calcium oxalate, disodium terephthalate, dilithium terephthalate, dipotassium terephthalate, Sodium laurate, potassium laurate, sodium myristate, potassium myristate, calcium myristate, barium myristate, sodium octacolate, calcium octacolate, sodium stearate, potassium stearate, lithium stearate, calcium stearate, magnesium stearate , Barium stearate, sodium montanate, calcium montanate, sodium toluate, sodium salicylate, potassium salicylate, salicy Organic carboxylic acid metal salts such as zinc acid, aluminum dibenzoate, β-naphthoic acid sodium, β-naphthoic acid potassium, sodium cyclohexanecarboxylic acid and the like, and organic sulfonic acid metal salts such as sodium p-toluenesulfonate and sodium sulfoisophthalate. Can be mentioned.

Also, organic carboxylic acid amides such as stearic acid amide, ethylenebislauric acid amide, palmitic acid amide, hydroxystearic acid amide, erucic acid amide, trimesic acid tris (tert-butylamide), low density polyethylene, high density polyethylene, polyiso Propylene, polybutene, poly-4-methylpentene, poly-3-methylbutene-1, polyvinylcycloalkane, polyvinyltrialkylsilane, high melting point polylactic acid, sodium salt of ethylene-acrylic acid copolymer, sodium of styrene-maleic anhydride copolymer Examples thereof include salts (so-called ionomers), benzylidene sorbitol and derivatives thereof such as dibenzylidene sorbitol.
Among these, at least one selected from talc and organic carboxylic acid metal salts is preferably used. Only one type of crystallization accelerator may be used in the present invention, or two or more types may be used in combination.
The content of the crystallization accelerator is preferably 0.01 to 30 parts by weight, more preferably 0.05 to 20 parts by weight per 100 parts by weight of the polymer material.

<Filler>
The material used for the production of the polylactic acid strand can contain an organic or inorganic filler. By containing the filler component, a molded product having excellent mechanical properties, heat resistance, and moldability can be obtained.
Organic fillers such as rice husks, wood chips, okara, waste paper ground materials, clothing ground materials, cotton fibers, hemp fibers, bamboo fibers, wood fibers, kenaf fibers, jute fibers, banana fibers, coconut fibers Plant fibers such as pulp or cellulose fibers processed from these plant fibers and fibrous fibers such as animal fibers such as silk, wool, angora, cashmere and camel, synthetic fibers such as polyester fibers, nylon fibers and acrylic fibers , Paper powder, wood powder, cellulose powder, rice husk powder, fruit husk powder, chitin powder, chitosan powder, protein, starch and the like. From the viewpoint of moldability, powdery materials such as paper powder, wood powder, bamboo powder, cellulose powder, kenaf powder, rice husk powder, fruit husk powder, chitin powder, chitosan powder, protein powder, and starch are preferred. Powder, bamboo powder, cellulose powder and kenaf powder are preferred. Paper powder and wood powder are more preferable. Paper dust is particularly preferable.

These organic fillers may be those directly collected from natural products, but may also be those obtained by recycling waste materials such as waste paper, waste wood and old clothes.
The wood is preferably a softwood material such as pine, cedar, oak or fir, or a hardwood material such as beech, shii or eucalyptus.
Paper powder is an adhesive from the viewpoint of moldability, especially emulsion adhesives such as vinyl acetate resin emulsions and acrylic resin emulsions that are usually used when processing paper, polyvinyl alcohol adhesives, polyamide adhesives Those containing hot melt adhesives such as are preferably exemplified.
The blending amount of the organic filler is not particularly limited, but from the viewpoint of moldability and heat resistance, it is preferably 1 to 300 parts by weight, more preferably 5 to 200 parts by weight, per 100 parts by weight of the polymer material. More preferably, it is 10-150 weight part, Most preferably, it is 15-100 weight part. If the blending amount of the organic filler is less than 1 part by weight, the effect of improving the moldability of the composition is small, and if it exceeds 300 parts by weight, uniform dispersion of the filler becomes difficult, or other than moldability and heat resistance In addition, the strength and appearance of the material may decrease, which is not preferable.

For use in the production of the polylactic acid strand, it is preferable to contain an inorganic filler. A composition excellent in mechanical properties, heat resistance and moldability can be obtained by the inorganic filler. As the inorganic filler used in the present invention, a fibrous, plate-like, or powder-like material used for reinforcing ordinary thermoplastic resins can be used.
Specifically, for example, carbon nanotube, glass fiber, asbestos fiber, carbon fiber, graphite fiber, metal fiber, potassium titanate whisker, aluminum borate whisker, magnesium whisker, silicon whisker, wollastonite, imogolite, sepiolite, Asbestos, slag fiber, zonolite, gypsum fiber, silica fiber, silica-alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, and other fibrous inorganic fillers, layered silicate, and organic onium ions Layered silicate, glass flake, non-swelling mica, graphite, metal foil, ceramic beads, talc, clay, mica, sericite, zeolite, bentonite, dolomite, kaolin, powdered silicic acid, feldspar powder, potassium titanate, shirasuba Plates and particles of inorganic fillers such as carbon nanoparticles such as carbon, calcium carbonate, magnesium carbonate, barium sulfate, calcium oxide, aluminum oxide, titanium oxide, aluminum silicate, silicon oxide, gypsum, novaculite, dosonite and white clay fullerene Agents.

Specific examples of layered silicates include smectite clay minerals such as montmorillonite, beidellite, nontronite, saponite, hectorite, and soconite, various clay minerals such as vermiculite, halosite, kanemite, and kenyanite, Li-type fluorine teniolite, Na And swellable mica such as Li-type fluorine teniolite, Li-type tetrasilicon fluorine mica and Na-type tetrasilicon fluorine mica. These may be natural or synthetic. Among these, smectite clay minerals such as montmorillonite and hectorite, and swellable synthetic mica such as Li type fluorine teniolite and Na type tetrasilicon fluorine mica are preferable.
Among these inorganic fillers, fibrous or plate-like inorganic fillers are preferable, and glass fiber, wollastonite, aluminum borate whisker, potassium titanate whisker, mica, and kaolin, a cation-exchanged layered silicate. Is preferred. The aspect ratio of the fibrous filler is preferably 5 or more, more preferably 10 or more, and further preferably 20 or more.

Such a filler may be coated or converged with a thermoplastic resin such as an ethylene / vinyl acetate copolymer or a thermosetting resin such as an epoxy resin, or may be treated with a coupling agent such as aminosilane or epoxysilane. May be.
The amount of the inorganic filler is preferably 0.1 to 200 parts by weight, more preferably 0.5 to 100 parts by weight, still more preferably 1 to 50 parts by weight, particularly preferably 1 to 100 parts by weight of polylactic acid. -30 parts by weight, most preferably 1-20 parts by weight.

<Release agent>
The material used for producing the polylactic acid strand can contain a release agent. As the mold release agent used in the present invention, those used for ordinary thermoplastic resins can be used.
Specific examples of release agents include fatty acids, fatty acid metal salts, oxy fatty acids, paraffins, low molecular weight polyolefins, fatty acid amides, alkylene bis fatty acid amides, aliphatic ketones, fatty acid partial saponified esters, fatty acid lower alcohol esters, fatty acid polyvalents. Examples include alcohol esters, fatty acid polyglycol esters, and modified silicones. By blending these, a polylactic acid molded product excellent in mechanical properties, moldability, and heat resistance can be obtained.
Fatty acids having 6 to 40 carbon atoms are preferred. Specifically, oleic acid, stearic acid, lauric acid, hydroxystearic acid, behenic acid, arachidonic acid, linoleic acid, linolenic acid, ricinoleic acid, palmitic acid, montan Examples thereof include acids and mixtures thereof. The fatty acid metal salt is preferably an alkali metal salt or alkaline earth metal salt of a fatty acid having 6 to 40 carbon atoms, and specific examples include calcium stearate, sodium montanate, calcium montanate, and the like.

Examples of the oxy fatty acid include 1,2-oxysteric acid. Paraffin having 18 or more carbon atoms is preferable, and examples thereof include liquid paraffin, natural paraffin, microcrystalline wax, petrolactam and the like.
As the low molecular weight polyolefin, for example, those having a molecular weight of 5000 or less are preferable, and specific examples include polyethylene wax, maleic acid-modified polyethylene wax, oxidized type polyethylene wax, chlorinated polyethylene wax, and polypropylene wax. Fatty acid amides having 6 or more carbon atoms are preferred, and specific examples include oleic acid amide, erucic acid amide, and behenic acid amide.
The alkylene bis fatty acid amide is preferably one having 6 or more carbon atoms, and specifically includes methylene bis stearic acid amide, ethylene bis stearic acid amide, N, N-bis (2-hydroxyethyl) stearic acid amide and the like. As the aliphatic ketone, those having 6 or more carbon atoms are preferable, and examples thereof include higher aliphatic ketones.

Examples of the fatty acid partial saponified ester include a montanic acid partial saponified ester. Examples of the fatty acid lower alcohol ester include stearic acid ester, oleic acid ester, linoleic acid ester, linolenic acid ester, adipic acid ester, behenic acid ester, arachidonic acid ester, montanic acid ester, isostearic acid ester and the like.
Examples of fatty acid polyhydric alcohol esters include glycerol tristearate, glycerol distearate, glycerol monostearate, pentaerythritol tetrastearate, pentaerythritol tristearate, pentaerythritol dimyristate, pentaerythritol Examples include tall monostearate, pentaerythritol adipate stearate, sorbitan monobehenate and the like. Examples of fatty acid polyglycol esters include polyethylene glycol fatty acid esters and polypropylene glycol fatty acid esters.

Examples of the modified silicone include polyether-modified silicone, higher fatty acid alkoxy-modified silicone, higher fatty acid-containing silicone, higher fatty acid ester-modified silicone, methacryl-modified silicone, and fluorine-modified silicone.
Of these, fatty acid, fatty acid metal salt, oxy fatty acid, fatty acid ester, fatty acid partial saponified ester, paraffin, low molecular weight polyolefin, fatty acid amide, and alkylene bis fatty acid amide are preferred, and fatty acid partial saponified ester and alkylene bis fatty acid amide are more preferred. Of these, montanic acid ester, montanic acid partial saponified ester, polyethylene wax, acid value polyethylene wax, sorbitan fatty acid ester, erucic acid amide, and ethylene bisstearic acid amide are preferred, and particularly, montanic acid partial saponified ester and ethylene bisstearic acid amide are preferred. preferable.
A mold release agent may be used by 1 type and may be used in combination of 2 or more type. The content of the release agent is preferably 0.01 to 3 parts by weight, more preferably 0.03 to 2 parts by weight with respect to 100 parts by weight of the polymer material.

<Antistatic agent>
The material used for producing the polylactic acid strand can contain an antistatic agent. Examples of the antistatic agent include quaternary ammonium salt compounds such as (β-lauramidopropionyl) trimethylammonium sulfate and sodium dodecylbenzenesulfonate, sulfonate compounds, and alkyl phosphate compounds.
One type of antistatic agent may be used, or two or more types may be used in combination. The content of the antistatic agent is preferably 0.05 to 5 parts by weight, more preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the polymer material.

<Plasticizer>
The material used for producing the polylactic acid strand can contain a plasticizer. As the plasticizer, generally known plasticizers can be used. Examples include polyester plasticizers, glycerin plasticizers, polycarboxylic acid ester plasticizers, phosphate ester plasticizers, polyalkylene glycol plasticizers, and epoxy plasticizers.
As a polyester plasticizer, acid components such as adipic acid, sebacic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid and ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, Examples thereof include polyesters composed of diol components such as 1,6-hexanediol and diethylene glycol, and polyesters composed of hydroxycarboxylic acids such as polycaprolactone. These polyesters may be end-capped with a monofunctional carboxylic acid or a monofunctional alcohol.
Examples of the glycerol plasticizer include glycerol monostearate, glycerol distearate, glycerol monoacetomonolaurate, glycerol monoacetomonostearate, glycerol diacetomonooleate, and glycerol monoacetomonomontanate.

Polyvalent carboxylic acid plasticizers include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diheptyl phthalate, dibenzyl phthalate, butyl benzyl phthalate, trimellitic acid tributyl, trimellitic acid trioctyl, Trimellitic acid esters such as trihexyl meritate, isodecyl adipate, adipic acid esters such as adipate-n-decyl-n-octyl, citrate esters such as tributyl acetylcitrate, and bis (2-ethylhexyl) azelate Examples include sebacic acid esters such as azelaic acid ester, dibutyl sebacate, and bis (2-ethylhexyl) sebacate.
Examples of the phosphate ester plasticizer include tributyl phosphate, tris phosphate (2-ethylhexyl), trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, diphenyl-2-ethylhexyl phosphate, and the like.

Polyalkylene glycol plasticizers such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly (ethylene oxide-propylene oxide) block and / or random copolymers, ethylene oxide addition polymers of bisphenols, tetrahydrofuran addition polymers of bisphenols, etc. And end-capping compounds such as a terminal epoxy-modified compound, a terminal ester-modified compound, and a terminal ether-modified compound.
Examples of the epoxy plasticizer include an epoxy triglyceride composed of alkyl epoxy stearate and soybean oil, and an epoxy resin using bisphenol A and epichlorohydrin as raw materials.

  Specific examples of other plasticizers include benzoic acid esters of aliphatic polyols such as neopentyl glycol dibenzoate, diethylene glycol dibenzoate, triethylene glycol-bis (2-ethylbutyrate), and fatty acids such as stearamide. Examples thereof include fatty acid esters such as amide and butyl oleate, oxyacid esters such as methyl acetylricinoleate and butyl acetylricinoleate, pentaerythritol, various sorbitols, polyacrylic acid esters, silicone oils, and paraffins.

As the plasticizer, at least one selected from polyester-type plasticizers and polyalkylene-type plasticizers can be preferably used, and only one type may be used, or two or more types may be used in combination.
The content of the plasticizer is preferably 0.01 to 30 parts by weight, more preferably 0.05 to 20 parts by weight, and further preferably 0.1 to 10 parts by weight per 100 parts by weight of the polymer material. In the present invention, each of the crystallization nucleating agent and the plasticizer may be used alone, or more preferably used in combination.

<Impact resistance improver>
The material used for producing the polylactic acid strand can contain an impact resistance improving agent. The impact resistance improver is one that can be used to improve the impact resistance of a thermoplastic resin, and is not particularly limited. For example, at least one selected from the following impact resistance improvers can be used.

  Specific examples of impact modifiers include ethylene-propylene copolymers, ethylene-propylene-nonconjugated diene copolymers, ethylene-butene-1 copolymers, various acrylic rubbers, ethylene-acrylic acid copolymers and their Alkali metal salts (so-called ionomers), ethylene-glycidyl (meth) acrylate copolymers, ethylene-acrylate copolymers (for example, ethylene-ethyl acrylate copolymers, ethylene-butyl acrylate copolymers), modified ethylene -Propylene copolymer, diene rubber (eg polybutadiene, polyisoprene, polychloroprene), diene and vinyl copolymer (eg styrene-butadiene random copolymer, styrene-butadiene block copolymer, styrene-butadiene-styrene block copolymer) Coalescence, styrene Soprene random copolymer, styrene-isoprene block copolymer, styrene-isoprene-styrene block copolymer, polybutadiene graft copolymerized with styrene, butadiene-acrylonitrile copolymer), polyisobutylene, isobutylene and butadiene Or a copolymer with isoprene, natural rubber, thiocol rubber, polysulfide rubber, polyurethane rubber, polyether rubber, epichlorohydrin rubber and the like can be mentioned.

In addition, those having various cross-linking degrees, various micro structures such as those having a cis structure, a trans structure, etc., a core layer and one or more shell layers covering the core layer, and adjacent layers are composed of heterogeneous polymers. A so-called core-shell type multi-layered polymer can also be used.
Furthermore, the various (co) polymers mentioned in the above specific examples may be any of random copolymers, block copolymers, block copolymers and the like, and can be used as the impact resistance improver of the present invention.
The impact resistance improver is preferably 1 to 30 parts by weight, more preferably 5 to 20 parts by weight, and still more preferably 10 to 20 parts by weight with respect to 100 parts by weight of polylactic acid.

<Others>
The material used for the production of the polylactic acid strand may contain a thermosetting resin such as a phenol resin, a melamine resin, a thermosetting polyester resin, a silicone resin, or an epoxy resin within a range not departing from the gist of the present invention. Further, the material may contain a flame retardant such as bromine, phosphorus, silicone, and antimony compound as long as it does not contradict the gist of the present invention. Colorants containing organic and inorganic dyes and pigments, for example, oxides such as titanium dioxide, hydroxides such as alumina white, sulfides such as zinc sulfide, ferrocyanides such as bitumen, and chromium such as zinc chromate Contains acid salts, sulfates such as barium sulfate, carbonates such as calcium carbonate, silicates such as ultramarine, phosphates such as manganese violet, carbon such as carbon black, metal colorants such as bronze powder and aluminum powder, etc. You may let them. Also, nitroso type such as naphthol green B, nitro type such as naphthol yellow S, azo type such as naphthol red and chromophthal yellow, phthalocyanine type such as phthalocyanine blue and fast sky blue, and condensed polycyclic coloring such as indanthrone blue An agent or the like may be included. However, depending on the type of colorant, the reactivity of the end-capping agent may be hindered, such as by modifying the end-capping agent due to its reactivity such as acidity. Is preferred. Further, additives such as a slidability improving agent such as graphite and fluorine resin may be contained. These additives can be used alone or in combination of two or more.

<Method for producing polylactic acid strand>
The method for producing the polylactic acid strand of the present invention comprises:
(I) Melting a polylactic acid resin having a lactic acid content of 50% or more, a molecular weight of 100,000 to 350,000, and a melting point of 140 to 180 ° C at 200 to 240 ° C,
(Ii) The molten polylactic acid resin is extruded from a base at 230 to 260 ° C. to form a filamentous material,
(Iii) The filamentous material is cooled and solidified in cooling water at a temperature of Tg to (Tg + 20) ° C. within a distance of 1 to 5 cm from the base surface to the liquid level of the water-cooled bath, and then water or air at 0 to 30 ° C. Again, solidify by cooling to make a strand.
(Iv) The cooled strand is taken up at a speed of 5 to 20 m / min, stretched in a single stage or multiple stages at a magnification of 1.5 to 3 times at 80 to 120 ° C., and (v) the stretched strand Each step of cooling and solidifying with air at 10 to 30 ° C. is included when the film is drawn at the same speed as in stretching.

(Melting step (i))
The melting step (i) is a step of melting the polylactic acid resin in the range of 200 to 240 ° C. The polylactic acid resin has a lactic acid content of 50% or more, a molecular weight of 100,000 to 350,000, and a melting point of 140 to 180 ° C.
The melting zone is not particularly limited as long as it is a temperature at which the polylactic acid resin at 200 to 240 ° C. is melted, but is preferably 200 to 240 ° C., more preferably 220 to 240 ° C.

(Extrusion process (ii))
The extrusion step (ii) is a step of extruding a molten polylactic acid resin from a base at 230 to 260 ° C. to form a filamentous material.
When the die temperature is less than 230 ° C., the melt viscosity is high and the strands pulsate, which is not preferable because the fluctuation width of the yarn diameter increases. If the temperature exceeds 260 ° C., the melt viscosity becomes too low, so that it is difficult to match the yarn diameter, and durability is lowered due to generation of a low molecular compound due to thermal decomposition, which is not preferable.

(Cooling and solidification step (iii))
In the cooling and solidification step (iii), the obtained filamentous material is cooled and solidified in cooling water at a temperature of Tg to (Tg + 20) ° C. in a range of 1 to 5 cm from the base surface to the liquid surface of the water cooling bath, This is a step of cooling and solidifying again with water or air at 0 to 30 ° C. to form a strand.
The distance from the base surface to the liquid level of the water-cooled bath is in the range of 1 to 5 cm. Preferably it is 1-4 cm. If it is less than 1 cm, the portion where the liquid is applied to the base surface is rapidly cooled, and the method of stretching by free fall is not stable, so the yarn diameter varies, which is not preferable. If the length exceeds 5 cm, the strand is sufficiently stretched, but since the cooling time becomes long, the strand fluctuates from side to side, so that the fluctuation width of the yarn diameter increases, and further, the roundness cannot be maintained. It is not preferable.

The cooling water temperature of the first cooling bath is in the range of Tg to Tg + 20 ° C. of polylactic acid. Rapid cooling below Tg is not preferred because the cooling rate in the strand and the surface are significantly different, and the roundness cannot be maintained due to shrinkage. If Tg + 20 ° C. is exceeded, the strands are not solidified and are crushed by a roller or the like, so that the roundness cannot be maintained, which is not preferable.
Furthermore, in the second stage, it is preferable to cool and solidify at 0 to 30 ° C. with water or air. Since the strand of the present invention is as thick as 1 to 3.5 mm in diameter, the inside is not yet cooled and solidified only by the first cooling bath, so it is crushed by the stretching roller and can maintain roundness. Therefore, the second cooling bath is characterized by being cooled and solidified again.

(Extension process (iv))
The drawing step (iv) is a step of drawing the cooled strand at a speed of 5 to 20 m / min and drawing it at 80 to 120 ° C. at a magnification of 1.5 to 3 times in one or more stages. In the stretching step (iv), the film is stretched 1.5 to 3 times at 80 to 120 ° C. If it is less than 1.5 times, the obtained strand is easy to break, and thus it is impossible to stably form a three-dimensional shape. If it exceeds 3 times, the unstretched strand becomes too thick, so that it is easy to be crushed by the first stretching roller and the roundness cannot be maintained.
As the stretching method, dry heat stretching using hot air, heat medium stretching using a heating medium such as water, and the like can be used. Since the first-stage drawing is a process for constructing the basic structure of the strand, it is preferable to use heating medium drawing that can be heated uniformly. Stretching may be completed in one stage or in multiple stages. When stretching in the second and subsequent stages, either heat medium stretching or dry heat stretching may be used. Since the second stage stretching is usually higher than the first stage stretching temperature, dry heat stretching is often employed from the viewpoint of temperature uniformity.

(Heat treatment process)
You may heat-process after extending | stretching. Heat treatment at 80 to 120 ° C. is preferably performed at 0.9 to 1.1 times.

(Cooling and solidifying step (v))
The cooling and solidifying step (v) is a step of cooling and solidifying with air at 10 to 30 ° C. when the drawn strands are drawn at the same speed.
At the time of winding, it is preferable not to wind immediately, but to wind after cooling by air cooling at 10 to 30 ° C. If it is less than 10 degreeC, although it is preferable for cooling, since it will dew condensation, since the obtained strand must be dried again, it is not preferable. If the temperature exceeds 30 ° C., the temperature of the strand becomes close to Tg, so that it is deformed, the roundness cannot be maintained, and the yarn diameter is greatly shaken.

(Polylactic acid strand)
According to the method for producing a polylactic acid strand of the present invention, the average value of the diameter is 1.0 to 3.5 mm, the diameter variation rate is 3% or less, and the diameter variation range is 15% or less. A polylactic acid strand having a heat shrinkage of 10% or more when immersed in silicone oil held for 1 minute is obtained.
The number of polylactic acid strands is not particularly limited, and may be appropriately changed depending on the size of the equipment.

In the present invention, attention is paid to the fact that the cooling and solidification and drawing behavior of the polylactic acid resin is very sensitive to the stability and roundness of the yarn diameter, and a high-quality polylactic acid strand is obtained with good yarn production. Thus, a manufacturing method for providing a necessary amount of heat has been found.
That is, in order to obtain a polylactic acid strand having a strand breakage, a stable yarn diameter, and a roundness when stretching at the number of stretching steps necessary for obtaining a high-quality strand and a stretching ratio, each stretching is performed. There are optimum drawing temperature and draw ratio in the number of stages, and in order to give the amount of heat necessary for drawing the polylactic acid strand within the drawing temperature range, the winding speed must be set within a certain range. It is what I found. In spite of the drawing temperature being within the conditions, when the winding speed is out of the conditions, the necessary amount of heat cannot be given to the polylactic acid strand, and the variation in the yarn diameter and the roundness can be maintained. It becomes impossible.

<Figure 2>
Next, an example of the method for producing the polylactic acid strand of the present invention will be described with reference to FIG. A manufacturing method may be adopted.

(Melting step (i), extrusion step (ii))
The pellet hopper (6) is filled with polylactic acid resin, melted using an extruder (7), weighed with a gear pump (8), and then passed through a filter such as a metal non-woven fabric in the pack (9) from the die. Extrude. At this time, the polylactic acid resin to be used is preferably dried to a moisture content of about 0 to 600 ppm using a vacuum dryer or the like from the viewpoints of yarn production and quality. Further, when the biting property of the extruder is poor, it is possible to reduce the biting failure by previously coating a polylactic acid resin with a very small amount of a lubricant such as calcium stearate. The spinning temperature may be appropriately set in consideration of discharge stability and thermal decomposition of the polylactic acid resin, but is preferably in the range of 200 to 240 ° C.
You may attach a heating cylinder and / or a heat insulation pipe | tube to the nozzle | cap | die surface lower part as needed. The in-cylinder atmosphere temperature is not particularly limited, but is preferably near the melting point of the polylactic acid resin.

(Cooling and solidification step (iii))
The discharged strand (10) is cooled and solidified by the first cooling bath (11). Further, before stretching, the second cooling bath (12) is cooled and solidified again. The first cooling bath is preferably Tg to (Tg + 20) ° C., and the temperature of the second cooling bath is preferably 0 to 30 ° C.

(Extension process (iv))
The obtained strand (10) is subjected to the stretching step after being wound once or without being wound once. Stretching is performed by a multistage stretching method of one stage or two or more stages in order to obtain a polylactic acid strand suitable for three-dimensional modeling. The stretching method is not particularly limited, and a generally known stretching method using stretching rolls (13) and (14) such as a multi-cylinder roll may be adopted. The stretching conditions are carried out according to the production method of the present invention described above. That is, the first-stage stretching is performed between the first roller (13) and the second roller (14), the stretching temperature is set to 80 to 120 ° C., and the stretching ratio is set to 1.5 to 3.0 times. Although there is no limitation in particular in the heat medium used in 1st extending | stretching, it is preferable that it is a extending | stretching bath (15) using a heat medium (water etc.) from a viewpoint of temperature uniformity. When carrying out two or more stages of multi-stage stretching, the strands for which the first stage of stretching has been completed are subsequently subjected to the second stage of stretching. In stretching after the second stage, since it is generally set higher than the temperature of the first stage, it is preferable to use a dry hot air heater.

(Heat treatment process)
The strand (10) drawn in the drawing step is preferably subjected to heat treatment from the viewpoint of improving dimensional stability. A generally known method may be adopted as the heat treatment method, but it is preferable to adopt the heat treatment method of the present invention described above in order to satisfy the yarn forming property and the dimensional stability at the same time. That is, it is preferable to heat-treat the polylactic acid strand (10) in a hot air oven (16) at 80 to 100 ° C. at a magnification of 0.9 to 1.1 after stretching.

(Cooling and solidification step (iii))
Then, before winding up, dimensional stability is acquired by further cooling with a 10-30 degreeC hot-air oven (17). Finally, it winds up with a winder (18).

<Method for manufacturing a three-dimensional structure>
The manufacturing method of the three-dimensional structure of the present invention is as follows:
(I) The polylactic acid strand is supplied to the discharge head, the polylactic acid strand is melted in the discharge head, and (ii) the melted polylactic acid is discharged from the discharge head to a specified position and deposited in layers. Solidify lactic acid,
This method includes each step and repeats the steps (i) to (ii). This method is called a melt lamination method or a melt deposition method.
The discharge head is also called a discharge nozzle or an extrusion head, and has a function of discharging a polymer material melt. In the present invention, the polylactic acid strand of the present invention is used as the polymer material.

<3D objects>
This invention includes the three-dimensional structure using the polylactic acid strand obtained by the manufacturing method of this invention.

  Hereinafter, the present invention will be described by way of examples.

Various characteristics were measured by the following methods.
(1) Average value of strand diameter, variation rate, variation range:
The average value, variation rate, and variation width of the polylactic acid strand diameter were measured under the following conditions using a dimension / outer diameter measuring device LS-9000 (manufactured by Keyence Corporation).

・ Strand scanning speed: 40 m / min ・ Measurement speed: 16000 points / second = 42 μm / point ・ Average number of moving points: 8 points ・ Sampling interval: 50 mm / point ・ Number of sampling points: 1000 points Strand outer diameter value of 1000 sampled points From the average value (D), standard deviation (σ), maximum value (D _Max ), and minimum value (D _Min ) of (mm), the average value, fluctuation rate, and fluctuation width of the strand diameter are calculated by the following formula (v). did.
Average value (mm) = D
Fluctuation rate (%) = σ / D × 100
Fluctuation width (%) = (D _Max −D _Min ) / D × 100 (v)

(2) Measurement of heat shrinkage:
A sufficiently long polylactic acid strand was fixed to a stainless steel frame, and was left to stand in a hot air dryer at 110 ° C. for 1 hour to perform heat setting. Of the endothermic peaks at 130 ° C. or higher in the temperature rising DSC (Differential Scanning Calorimetry) spectrum measured at a temperature rising rate of 20 ° C./min from 30 ° C. to 250 ° C., 5 mg is sampled from the strand after heat setting. The peak temperature of the strongest peak was taken as the melting point after heat setting. The strand after heat setting was cut to a length of 150 mm, and a marked line was attached to a portion 100 mm from one end (referred to as end A). The other end (referred to as end B) was held with tweezers and immersed in silicone oil that was maintained at the melting point after heat setting so that the portion from end A to the marked line was sufficiently immersed in the silicone oil. After soaking for 1 minute, the silicone oil was taken out, wiped with excess oil, cooled to room temperature, and the length from the end A to the marked line was measured to obtain Lmm. The thermal contraction rate was calculated according to the formula (vi).
Thermal contraction rate (%) = 100−L (vi)

(3) DSC (differential scanning calorimetry) measurement of the strand surface:
Using a precision nipper, the polylactic acid strand was cut to a length of 1 mm, and the side surface (a portion having a thickness of (diameter / 4) from the outer circumference of the circle) was cut once into a comb mold to obtain a sample piece. This was repeated at any point of the polylactic acid strand, and a total of 5 mg sample pieces were used for DSC measurement.
A sample piece of 5 mg was sealed in an aluminum seal cell (TA Instruments, Standard Pan, 900786.901 and TA Instruments, Standard Lid, 900779.901), and the DSC device was TA Instruments, TA- The DSC spectrum was obtained by performing a first temperature scan using 2920 under conditions of heating from 30 ° C. to 260 ° C. at a rate of 20 ° C./min under a nitrogen stream. Of the endothermic peaks at 130 ° C. or higher in this DSC spectrum, the peak with the highest peak intensity was taken as the melting peak. The melting point was the temperature at the peak of the melting peak. When there were many melting peaks, the peak temperature at the melting peak was the highest peak temperature.

(4) Modeling test with 3D modeling equipment:
A polylactic acid strand having an average diameter of 1.75 mm ± 0.5 mm was set in a melt deposition three-dimensional modeling apparatus (“BS01” manufactured by Bonsai Lab Co., Ltd., discharge nozzle diameter: 0.4 mm) and suitable for each strand sample. A modeling test was performed at the discharge head temperature under the following conditions.
Discharge head moving speed: 30 mm / min (when discharging resin), 130 mm / min (when discharging is stopped)
Discharge amount (magnification): 100%
Lamination pitch: 0.2mm
Retraction (retraction) amount when stopping discharge: 4mm
Retraction (retraction) speed when discharge is stopped: 50 mm / min Minimum molding time per layer: 5 seconds Number of outer shell layers: 3 layers Filling rate inside: 100%
Laminated bed temperature: 25 ° C
Atmospheric temperature: 25 ° C
Atmospheric relative humidity: 40%
During modeling, the model was not cooled by a fan or blower.

(4-1) Sagging evaluation:
Two cubes each having a side of 10 mm are used as a bridge girder. The bridge girder is arranged in parallel on the horizontal plane so that the distance between the centers of the bridge girder is 50 mm. A bridge-shaped three-dimensional model with a handed shape was designed by three-dimensional CAD, and this model was formed under the above conditions. The distance Z between the portion where the plate-shaped portion of the formed three-dimensional model was closest to the laminated bed and the laminated bed was measured, and the amount of sagging was calculated from the following equation.
Sagging amount (mm) = 10−Z (vii)
The modeling was repeated three times to calculate the average value of the sagging amount, and the average value was 0 mm or more and less than 2 mm, and the pass was 2 mm or more and less than 4 mm, and 4 mm or more was rejected.
(4-2) Evaluation of discharge / stop responsiveness 25 square pillars each having a square cross section of 2 mm and a height of 20 mm are placed on 5 × 5 square lattice points drawn at intervals of 10 mm on a horizontal plane. The arranged three-dimensional model was designed by three-dimensional CAD, and this model was formed under the above conditions. The dimension of the modeled three-dimensional model was measured with a caliper, and the number of prisms having a portion of 3 mm or more out of the two sides of the cross section of the prism was defined as the modeling failure number. The modeling was repeated three times to calculate the average value of the number of modeling failures, and the average value of 0 or more and less than 2 passed, 2 or more and less than 5 passed, and 5 or more failed.
(4-3) Stability of modeling A three-dimensional model in which 25 square pillars with a 10 mm cross-section and a height of 100 mm are placed on 5 × 5 square lattice points drawn at 20 mm intervals on a horizontal plane. Was designed by three-dimensional CAD, and this model was formed under the above conditions. The polylactic acid strand used for modeling used a thing sufficiently exceeding the weight of 300 g (volume: 250 cm 3, continuous length: about 104 m). When the modeling was completed without any abnormality, it was accepted, and when the discharge amount was reduced in the middle or the discharge was stopped, it was rejected.
The following were synthesized as polymer materials.

[Production Example 1] Poly L-lactic acid resin (A1):
To 100 parts by weight of L-lactide (manufactured by Musashino Chemical Laboratory, Inc., optical purity 100%), 0.005 parts by weight of tin octylate was added, and 180 ° C. in a reactor equipped with a stirring blade in a nitrogen atmosphere. The mixture was reacted at 0 ° C. for 2 hours, phosphoric acid equivalent to 1.2 times the amount of tin octylate was added, and then the remaining lactide was removed at 13.3 Pa to obtain chips, thereby obtaining a poly L-lactic acid resin.
The resulting poly L-lactic acid resin had a weight average molecular weight of 152,000, a melting enthalpy (ΔHmh) of 49 J / g, a melting point (Tmh) of 175 ° C., a glass transition point (Tg) of 55 ° C., and a carboxyl group concentration of 13. Equivalent / ton.

[Production Example 2] Poly D-lactic acid resin:
A poly D-lactic acid resin is obtained in the same manner as in Production Example 1 except that D-lactide (manufactured by Musashino Chemical Laboratory, Inc., optical purity 100%) is used instead of L-lactide in Production Example 1. It was. The resulting poly-D-lactic acid resin has a weight average molecular weight of 151,000, a melting enthalpy (ΔHmh) of 48 J / g, a melting point (Tmh) of 175 ° C., a glass transition point (Tg) of 55 ° C., and a carboxyl group concentration of 14 Equivalent / ton.

[Production Example 3] Stereocomplex polylactic acid (A2):
100 parts by weight of polylactic acid resin comprising 50 parts by weight of each of poly L-lactic acid resin and poly D-lactic acid resin obtained in Production Examples 1 and 2 and phosphoric acid-2,2′-methylenebis (4,6-di-tert) -Butylphenyl) sodium ("Adekastab (registered trademark)" NA-11: manufactured by ADEKA Corporation) 0.04 parts by weight was mixed with a blender, dried at 110 ° C for 5 hours, and vented twin screw extrusion with a diameter of 30 mmφ Stereocomplex polylactic acid (A2) Got.
The resulting stereocomplex polylactic acid resin (A2) has a weight average molecular weight of 130,000, a melting enthalpy (ΔHms) of 56 J / g, a melting point (Tms) of 220 ° C., a carboxyl group concentration of 16 equivalents / ton, and stereocomplex crystallization. The degree (S) was 100%.

[Production Example 4] Cyclic carbodiimide (CC2: MW = 516)

o- nitrophenol (0.11 mol) and pentaerythrityl tetra bromide (0.025 mol), potassium carbonate (0.33mol), N, N- dimethylformamide 200ml in reactor installed with a stirrer and a heating device _{N 2} After charging in an atmosphere and reacting at 130 ° C. for 12 hours, DMF was removed under reduced pressure, and the resulting solid was dissolved in 200 ml of dichloromethane and separated three times with 100 ml of water. The organic layer was dehydrated with 5 g of sodium sulfate, and dichloromethane was removed under reduced pressure to obtain an intermediate product D (nitro form).

Next, intermediate product D (0.1 mol), 5% palladium carbon (Pd / C) (2 g), and 400 ml of ethanol / dichloromethane (70/30) were charged into a reactor equipped with a stirrer, and 5 hydrogen substitution was performed. The reaction was performed in a state where hydrogen was constantly supplied at 25 ° C., and the reaction was terminated when there was no decrease in hydrogen. When Pd / C was recovered and the mixed solvent was removed, an intermediate product E (amine body) was obtained.
Next, triphenylphosphine dibromide (0.11 mol) and 150 ml of 1,2-dichloroethane were charged and stirred in a reactor equipped with a stirring device, a heating device, and a dropping funnel in an N ₂ atmosphere. A solution prepared by dissolving the intermediate product E (0.025 mol) and triethylamine (0.25 mol) in 50 ml of 1,2-dichloroethane was gradually added dropwise thereto at 25 ° C. After completion of dropping, the reaction is carried out at 70 ° C. for 5 hours. Thereafter, the reaction solution was filtered, and the filtrate was separated 5 times with 100 ml of water. The organic layer was dehydrated with 5 g of sodium sulfate, and 1,2-dichloroethane was removed under reduced pressure to obtain an intermediate product F (triphenylphosphine compound).
Next, in a reactor equipped with a stirrer and a dropping funnel, di-tert-butyl dicarbonate (0.11 mol), N, N-dimethyl-4-aminopyridine (0.055 mol), dichloromethane under N ₂ atmosphere. 150 ml is charged and stirred. Thereto, 100 ml of dichloromethane in which the intermediate product F (0.025 mol) was dissolved was slowly added dropwise at 25 ° C. After dropping, react for 12 hours. Then, CC2 was obtained by refine | purifying the solid substance obtained by removing dichloromethane. The structure of CC2 was confirmed by NMR and IR.

[Production Example 5] End-capping agent-added poly L-lactic acid resin (A3):
99 parts by weight of A1, vacuum dried at 110 ° C. for 5 hours, supplied from the first supply port of the biaxial kneader, melt-kneaded while venting at a cylinder temperature of 210 ° C. and evacuating at 13.3 Pa, and then circular 1 part by weight of carbodiimide (CC2) was supplied from the second supply port, melted and kneaded at a cylinder temperature of 210 ° C., extruded and pelletized to obtain end-capping agent-added poly L-lactic acid (A3).
The obtained poly L-lactic acid resin had a weight average molecular weight of 182,000, a melting enthalpy (ΔHmh) of 43 J / g, a melting point (Tmh) of 173 ° C., a glass transition point (Tg) of 58 ° C., and a carboxyl group concentration of 0. Equivalent / ton.

[Production Example 6] White poly L-lactic acid resin with end-capping agent added (A4):
After A9 was vacuum dried at 99.2 parts by weight at 110 ° C. for 5 hours, it was supplied from the first supply port of the biaxial kneader and melt kneaded while venting at a cylinder temperature of 210 ° C. and evacuating at 13.3 Pa. Then, 0.8 parts by weight of titanium oxide powder (KA-30 manufactured by Titanium Industry Co., Ltd.) was supplied from the second supply port, melted and kneaded at a cylinder temperature of 210 ° C., and extruded to obtain white polylactic acid pellets (A4).
The obtained poly L-lactic acid resin had a weight average molecular weight of 183,000, a melting enthalpy (ΔHmh) of 39 J / g, a melting point (Tmh) of 173 ° C., a glass transition point (Tg) of 57 ° C., and a carboxyl group concentration of 0. Equivalent / ton.

[Production Example 7] Yellow poly L-lactic acid resin with end-capping agent added (A5):
After A9 was vacuum dried at 99.2 parts by weight at 110 ° C. for 5 hours, it was supplied from the first supply port of the biaxial kneader and melt kneaded while venting at a cylinder temperature of 210 ° C. and evacuating at 13.3 Pa. , 0.8 parts by weight of yellow pigment powder (Chrophtal (registered trademark) Yellow K 1210FP manufactured by BASF) was supplied from the second supply port, melted and kneaded at a cylinder temperature of 210 ° C., and extruded to give yellow polylactic acid pellets (A5). Obtained.
The obtained poly L-lactic acid resin had a weight average molecular weight of 181,000, a melting enthalpy (ΔHmh) of 39 J / g, a melting point (Tmh) of 173 ° C., a glass transition point (Tg) of 58 ° C., and a carboxyl group concentration of 0. Equivalent / ton.

[Production Example 8] Black poly L-lactic acid resin with end-capping agent added (A6):
A3 was vacuum-dried at 99.7 parts by weight at 110 ° C. for 5 hours, then supplied from the first supply port of the twin-screw kneader and melt-kneaded while venting at a cylinder temperature of 210 ° C. and evacuating at 13.3 Pa. Carbon black powder (Mitsubishi Chemical Corporation # 44) 0.3 part by weight was supplied from the second supply port, melt kneaded at a cylinder temperature of 210 ° C., and extruded to obtain black polylactic acid pellets (A6).
The obtained poly L-lactic acid resin had a weight average molecular weight of 181,000, a melting enthalpy (ΔHmh) of 36 J / g, a melting point (Tmh) of 173 ° C., a glass transition point (Tg) of 57 ° C., and a carboxyl group concentration of 0. Equivalent / ton.

[Example 1]
(Melting, extrusion)
The polylactic acid resin A1 was previously dried at 100 ° C. with a hot air dryer so that the moisture content was in the range of 200 ppm or less. 0.03 part of calcium stearate as a lubricant is added to 100 parts of polylactic acid resin, and uniformly blended is supplied to a single screw extruder of φ35 mm (L / D = 28) to a spinning temperature of 230 ° C. And melt extruded. The molten polymer was weighed with a gear pump, filtered through a metal nonwoven fabric filter in a pack, and discharged from a die with a hole diameter of 6 mmφ from a die with one hole.
(Cooling solidification)
The discharged polymer was cooled and solidified with hot water at 70 ° C., and then immediately cooled and solidified with a second cooling bath at 10 ° C., and then taken up at a speed of 20 m / min by the first roller.
(Stretching)
The drawn polylactic acid unstretched strand was continuously stretched twice without being wound once between the first roller and the second roller. The temperature of the stretching bath at that time was 80 ° C.
(Cooling solidification)
Subsequently, it was cooled and solidified in a hot air bath at 30 ° C. and wound up to obtain a polylactic acid strand. Table 1 shows the physical properties and evaluation results of the obtained polylactic acid strands. The modeling test was performed at a head temperature of 250 ° C.

[Example 2]
A polylactic acid strand was obtained in the same manner as in Example 1 except that the draw ratio was changed from 2 times to 3 times. Table 1 shows the physical properties and evaluation results of the strands. The modeling test was performed at a head temperature of 250 ° C.

[Example 3]
The stretched strand of Example 1 was produced in the same manner as in Example 1 except that heat treatment was performed in a hot air oven at 95 ° C. at a magnification of 1 between the third roller and the fourth roller. A strand was obtained. Table 1 shows the physical properties and evaluation results of the strands. The modeling test was performed at a head temperature of 250 ° C.

[Example 4]
A polylactic acid strand was obtained in the same manner as in Example 3 except that the draw ratio was changed from 2 to 3 times. Table 1 shows the physical properties and evaluation results of the strands. The modeling test was performed at a head temperature of 250 ° C.

[Example 5]
A polylactic acid strand was obtained in the same manner as in Example 3 except that 100 parts by weight of A2 was used instead of A1. Table 1 shows the physical properties and evaluation results of the strands. The modeling test was performed at a head temperature of 250 ° C.

[Example 6]
A polylactic acid strand was obtained in the same manner as in Example 1 except that 100 parts by weight of A3 was used instead of A1. Table 1 shows the physical properties and evaluation results of the strands. The modeling test was performed at a head temperature of 250 ° C.

[Example 7]
A polylactic acid strand was obtained in the same manner as in Example 3 except that 100 parts by weight of A3 was used instead of A1. Table 1 shows the physical properties and evaluation results of the strands. The modeling test was performed at a head temperature of 250 ° C.

[Example 8]
A white polylactic acid strand was obtained in the same manner as in Example 3 except that 100 parts by weight of A4 was used instead of A1. Table 1 shows the physical properties and evaluation results of the strands. The modeling test was performed at a head temperature of 250 ° C.

[Example 9]
A yellow polylactic acid strand was obtained in the same manner as in Example 3 except that 100 parts by weight of A5 was used instead of A1. Table 1 shows the physical properties and evaluation results of the strands. The modeling test was performed at a head temperature of 250 ° C.

[Example 10]
A black polylactic acid strand was obtained in the same manner as in Example 3 except that 100 parts by weight of A6 was used instead of A1. Table 1 shows the physical properties and evaluation results of the strands. The modeling test was performed at a head temperature of 250 ° C.

[Example 11]
A polylactic acid strand was obtained in the same manner as in Example 3 except that polylactic acid NW4060D manufactured by Nature Works LLC was used instead of A1. Table 1 shows the physical properties and evaluation results of the strands. The modeling test was performed at a head temperature of 220 ° C.

[Comparative Example 1]
(Melting extrusion)
The polylactic acid resin A1 was previously dried at 100 ° C. with a hot air dryer so that the moisture content was in the range of 200 ppm or less. 0.03 part of calcium stearate as a lubricant is added to 100 parts of polylactic acid resin, and uniformly blended is supplied to a single screw extruder of φ35 mm (L / D = 28) to a spinning temperature of 230 ° C. And melt extruded. The molten polymer was measured with a gear pump, filtered in a pack with a metal non-woven fabric filter, and discharged from a 1-hole base through a base with a hole diameter of 6 mmφ.
(Cooling solidification)
The discharged polymer was cooled and solidified with hot water at 70 ° C., and then immediately cooled and solidified with a second cooling bath at 10 ° C., and then taken up at a speed of 20 m / min by the first roller. The taken-out polylactic acid unstretched strand was wound up to obtain a polylactic acid unstretched strand. Table 1 shows the physical properties and evaluation results of the strands. The modeling test was performed at a head temperature of 250 ° C.

[Comparative Example 2]
(Melting extrusion)
The polylactic acid resin A1 was previously dried at 100 ° C. with a hot air dryer so that the moisture content was in the range of 200 ppm or less. 0.03 part of calcium stearate as a lubricant is added to 100 parts of polylactic acid resin, and uniformly blended is supplied to a single screw extruder of φ35 mm (L / D = 28) to a spinning temperature of 230 ° C. And melt extruded. The molten polymer was weighed with a gear pump, filtered through a metal nonwoven fabric filter in a pack, and discharged from a die with a hole diameter of 6 mmφ from a die with one hole.
(Cooling solidification)
The discharged polymer was cooled and solidified with hot water at 70 ° C., and then immediately cooled and solidified with a second cooling bath at 10 ° C., and then taken up at a speed of 20 m / min by the first roller.
(Heat treatment process)
The stretching process was not performed, and the heat treatment process was performed at 1 ×. The temperature of the heat treatment step is 95 ° C. A polylactic acid strand that was heat-treated without stretching was obtained. Table 1 shows the physical properties and evaluation results of the strands. The modeling test was performed at a head temperature of 250 ° C.

From these results, the average value of the diameter is 1.0 to 3.5 mm, the diameter variation rate represented by the following formula is 3% or less, and the diameter variation range is 15% or less, which is maintained at the melting point of the sample. It can be seen that when a polylactic acid strand having a heat shrinkage rate of 10% or more when immersed in a silicone oil for 1 minute is used for melt deposition three-dimensional modeling, excellent moldability is exhibited. Furthermore, in the spectrum where the temperature (DSC / 4) thickness portion from the surface of the strand was subjected to temperature rising DSC analysis, the temperature at the top of the crystal melting peak was 140 ° C. or higher, and the heat amount of the melting peak was 30 J / g or higher. It can be seen that when the full width at half maximum of the melting peak is 20 ° C. or less, particularly excellent discharge / stop response is exhibited.
Moreover, it turns out that such a polylactic acid strand can be manufactured by a specific discharge, cooling, and extending process.

  The material of the present invention exhibits desired performance as a material for three-dimensional modeling, and can be suitably used as a material for this application.

DESCRIPTION OF SYMBOLS 1 Discharge head 2 Laminated bed 3 Shaped bridge-girder-like structure 4 Design drawing of bridge-like structure to be shaped 5 Dropped discharged resin 6 Pellet hopper 7 Extruder 8 Gear pump 9 Pack 10 Strand 11 First cooling bath 12 Second cooling bath 13 Stretch roll 14 Stretch roll 15 Stretch bath 16 Hot air oven 17 Hot air oven 18 Winder

Claims (6)

The average value of the diameter is 1.0 to 3.5 mm, the diameter variation rate represented by the following formula (iii-1) is 3% or less, and the diameter variation range represented by the following formula (iii-2) is A polylactic acid strand having a heat shrinkage of 10% or more when immersed for 1 minute in silicone oil held at the melting point of the sample at 15% or less.
Diameter variation rate (%) = σ / D × 100 (iii-1)
Diameter fluctuation range (%) = (D _Max −D _Min ) / D × 100 (iii-2)
σ: Standard deviation of outer diameter D: Average value of outer diameter (mm)
D _Max : Maximum outer diameter D _Min : Minimum outer diameter The polylactic acid strand according to claim 1, wherein a portion having a thickness of (diameter / 4) from the surface of the strand satisfies A below.
A: In the spectrum analyzed by the temperature rise DSC, the temperature at the top of the crystal melting peak is 140 ° C. or higher, the calorie of the melting peak is 30 J / g or higher, and the half width of the melting peak is 20 ° C. or lower. The average value of the diameter is 1.0 to 3.5 mm, the diameter variation rate represented by the following formula (iii-1) is 3% or less, and the diameter variation range represented by the following formula (iii-2) is 15 Is a method for producing a polylactic acid strand having a heat shrinkage rate of 10% or more when immersed in a silicone oil held at the melting point of the sample for 1 minute,
Diameter variation rate (%) = σ / D × 100 (iii-1)
Diameter fluctuation range (%) = (D _Max −D _Min ) / D × 100 (iii-2)
σ: Standard deviation of outer diameter D: Average value of outer diameter (mm)
D _Max : Maximum value of outer diameter D _Min : Minimum value of outer diameter (i) Polylactic acid resin having a lactic acid content of 50% or more, a molecular weight of 100,000 to 350,000, and a melting point of 140 to 180 ° C. is 200. Melted at ~ 240 ° C,
(Ii) The molten polylactic acid resin is extruded from a base at 230 to 260 ° C. to form a filamentous material,
(Iii) The filamentous material is cooled and solidified in cooling water at a temperature of Tg to (Tg + 20) ° C. in a range of 1 to 5 cm from the base surface to the liquid level of the water-cooled bath, and then water or air at 0 to 30 ° C. And again, solidify by cooling to make a strand,
(Iv) The cooled strand is taken up at a speed of 5 to 20 m / min, stretched in a single stage or multiple stages at a magnification of 1.5 to 3 times at 80 to 120 ° C., and (v) the stretched strand When it is drawn at the same speed as stretching, it is cooled and solidified with air at 10 to 30 ° C.,
The manufacturing method of the polylactic acid strand containing each process. The manufacturing method according to claim 3, comprising a step of heat-treating at 80 to 100 ° C. after stretching, wherein the portion of the thickness (diameter / 4) satisfies the following A from the surface of the obtained polylactic acid strand.
A: In the spectrum analyzed by the temperature rise DSC, the temperature at the top of the crystal melting peak is 140 ° C. or higher, the calorie of the melting peak is 30 J / g or higher, and the half width of the melting peak is 20 ° C. or lower. (I) The polylactic acid strand is supplied to the discharge head, the polylactic acid strand is melted in the discharge head, and (ii) the melted polylactic acid is discharged from the discharge head to a specified position and deposited in layers. Solidify lactic acid,
A method for producing a three-dimensional structure including each step and repeating steps (i) to (ii), wherein the polylactic acid strand according to claim 1 or 2 is used as the polylactic acid strand. A manufacturing method of a three-dimensional structure.   A three-dimensional structure using a polylactic acid strand obtained by the production method according to claim 3 or 4.

Images