JP2012149205A - Polyglycolic acid composition, resin molding and molded product including polyglycolic acid and decomposition method of polyglycolic acid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a PGA composition in which PGA can be decomposed and removed in a short time by means of immersion in an aqueous alkali solution, to provide a PGA-containing resin molding or molded product partly containing the resin molding, and to provide a method for decomposing PGA in the resin molding or molded product.SOLUTION: The polyglycolic acid composition includes 100 pts.mass of polyglycolic acid and 1-25 pts.mass of water-soluble polymer or water-soluble oligomer, such as polyvinyl alcohol, polyalkylene glycol, polyacrylic acid or glycolic acid oligomer. The resin molding containing polyglycolic acid formed from the polyglycolic acid composition as well as the molded product partly containing the resin molding are provided. Furthermore, the method for decomposing polyglycolic acid included in the resin molding and molded product comprises bringing the resin molding containing polyglycolic acid into contact with an aqueous medium at a temperature of 50-200°C if desired, followed by immersing it for 10 seconds to 110 minutes in an aqueous alkali solution of a temperature 20-95°C with the concentration of 2-15 mass%.

Description

  The present invention relates to a polyglycolic acid composition in which the degradability of polyglycolic acid, which is a biodegradable resin, is promoted, a polyglycolic acid resin molded article, a molded article having the resin molded article in a part thereof, and a polyglycol The present invention relates to an acid decomposition method.

  Aliphatic polyesters such as polylactic acid and polyglycolic acid are attracting attention as biodegradable polymer materials that have a low environmental impact because they are decomposed by microorganisms or enzymes existing in nature such as soil and sea. In addition, since aliphatic polyester has biodegradable absorbability, it is also used as a medical polymer material such as surgical sutures and artificial skin.

  Aliphatic polyesters can be synthesized, for example, by dehydration polycondensation of α-hydroxycarboxylic acids such as glycolic acid and lactic acid. In order to efficiently synthesize high-molecular weight aliphatic polyesters, in general, α-hydroxycarboxylic acid is used. A method of synthesizing a bimolecular cyclic ester of an acid and subjecting the cyclic ester to ring-opening polymerization is employed. For example, polyglycolic acid is obtained by ring-opening polymerization of glycolide, which is a bimolecular cyclic ester of glycolic acid. Polylactic acid is obtained by ring-opening polymerization of lactide, which is a bimolecular cyclic ester of lactic acid.

  Among aliphatic polyesters, polyglycolic acid (hereinafter sometimes referred to as “PGA”) has high degradability, mechanical strength such as heat resistance and tensile strength, and particularly, a film or sheet. The gas barrier properties are excellent. In addition, PGA is expected to be used as an agricultural material, various packaging (container) materials and medical polymer materials by taking advantage of the high cycle time, dimensional stability, and chemical resistance based on the high crystallinity of PGA. In addition, applications are being developed alone or in combination with other resin materials. The manufacturing methods of these products include extrusion molding, injection molding, compression molding, injection compression molding, transfer molding, cast molding, stampable molding, blow molding, stretched film molding, inflation film molding, laminate molding, calendar molding, and foam molding. Melt molding and other molding methods such as RIM molding, FRP molding, powder molding or paste molding are employed. Further, paying attention to degradability and strength of PGA, its usefulness is recognized as a raw material or additive in the fields of paints, coating agents, inks, toners, agricultural chemicals, pharmaceuticals, cosmetics and the like.

  As a method of utilization utilizing the degradability of aliphatic polyesters such as polylactic acid and polyglycolic acid, the purpose of the final product is formed by temporarily adding a resin molded product member made of aliphatic polyester to the product intermediate. After being achieved, a technique for disassembling and removing a member of a resin molded product made of the aliphatic polyester is known.

  For example, Japanese Patent Laid-Open No. 2002-344116 (Patent Document 1) discloses that a conductive layer is formed by electroless plating on an insulating base having a predetermined shape formed by injection molding, and polylactic acid, aliphatic polyester, or poly A circuit component manufacturing method is disclosed in which a resin mask of a mixture or copolymer of lactic acid and aliphatic polyester is integrally formed, and after electrolytic plating, the resin mask is removed by hydrolysis with an alkaline aqueous solution. Further, Patent Document 1 discloses that a resin mask is formed by injecting a resin into an injection mold in which an insulator base is set. It is disclosed to immerse in a caustic (NaOH, KOH, etc.) aqueous solution of about 15% by mass and a temperature of about 25 to 70 ° C. for about 1 to 120 minutes.

  Japanese Unexamined Patent Application Publication No. 2009-62609 (Patent Document 2) discloses that the surface of a substrate formed by injection molding a thermoplastic resin as an insulator is roughened, and polyglycolic acid or polylactic acid is applied to the roughened surface. After partially covering with a coating material made of a simple substance, a mixture of polylactic acid and aliphatic polyester, or a copolymer, and electrolessly plating the surface of the substrate that is not covered with the coating material A method of manufacturing a molded circuit component is disclosed in which the coating material coated on the surface of the substrate is removed. Patent Document 2 discloses that a coating method of a coating material is formed by injecting a resin into an injection mold in which a base is set. Patent Document 2 discloses that the coating material is removed. It is disclosed to immerse in an aqueous solution of caustic alkali (NaOH, KOH, etc.) having an alkali compound concentration of 2 to 15 mass% and a temperature of 25 to 70 ° C. for about 1 to 120 minutes.

  Furthermore, as molding of a three-dimensional molded product (three-dimensional molded product) by three-dimensional lamination molding, a stereolithography method using a photocurable resin, a powder lamination method using a metal or resin powder, and melting and depositing the resin There are known a melt deposition method, a sheet lamination method in which paper, a resin sheet or a metal thin plate are laminated, an ink jet method in which a liquid or powdery resin or metal is jetted.

  In three-dimensional laminate molding, while forming a three-dimensional shape, while preventing the branching part and overhanging part from floating and forming a precise three-dimensional shape, while forming a support member and a dummy part There has been known a method of cutting and removing the support member and the dummy portion after forming a desired three-dimensional image. For example, JP-A-2-251419 (Patent Document 3) discloses forming a dummy portion.

  In Japanese Patent Laid-Open No. 9-123290 (Patent Document 4), in a three-dimensional shape forming method for forming an arbitrary three-dimensional shape, a pattern portion where the three-dimensional shape exists and a non-pattern portion where the three-dimensional shape does not exist have two different properties After forming the predetermined solid composed of the three-dimensional pattern portion and the non-patterned portion by forming a layer using the material, and sequentially laminating only the non-pattern portion in the predetermined solid It is disclosed that the removal is performed by utilizing the difference in properties. Patent Document 4 discloses that the properties include melting point, solubility or photodisintegration, and the formation of a three-dimensional shape is performed by jetting ink in a specific example, and further, resin, metal, ceramics, etc. It is disclosed that a method using powder may be used.

  Among aliphatic polyesters, PGA has high decomposability, heat resistance, and high crystallinity, and therefore, these masks, covering materials, support members, dummy portions, non-pattern portions, and the like (hereinafter referred to as “auxiliary members”). Expectation is also high as a material of a resin molded body used in the above.

  However, in the manufacturing process of the molded circuit component and the three-dimensional molded product, auxiliary members made of PGA are formed, and these products are molded and manufactured. Finally, the auxiliary members made of PGA are removed. There is a need to. As a method for removing the auxiliary member, as disclosed in Patent Documents 1 and 2, a molded body having a part of the auxiliary member made of PGA (for a final product such as a molded circuit component product or a three-dimensional molded product product). Is equivalent to an intermediate molded body)). However, when an auxiliary member made of PGA is disassembled and removed by alkali treatment, for example, a molded product body that becomes a final product such as a molded circuit component product or a three-dimensional molded product, that is, an auxiliary member made of PGA. Among the (intermediate) molded bodies provided with a portion of the PGA, a portion excluding the auxiliary member made of PGA may be deteriorated by contact with an alkaline aqueous solution, and a solution has been demanded.

  Further, when PGA is removed by alkali decomposition from a molded body containing an auxiliary member made of PGA and a metal such as copper or aluminum, for example, metal powder, corrosion of the metal is caused by contact with alkali. There was a need for a solution.

  If the concentration of the alkaline aqueous solution for decomposing and removing PGA is reduced or the contact treatment time between the resin molded product and the alkaline aqueous solution is shortened, the possibility of the deterioration of the target resin molded product is reduced. It takes a long time to remove PGA and is not efficient.

  Therefore, the PGA contained in the molded body partially including a resin molded product containing PGA, which can decompose and remove PGA in a short time and can suppress deterioration of various materials in contact with the alkaline aqueous solution. A decomposition method was desired.

  Furthermore, there is an increasing demand for controlling the speed of decomposition and removal of resin molded products containing PGA mainly composed of PGA. Japanese Patent Application Laid-Open No. 2004-168895 (Patent Document 5) discloses that the rate of enzymatic degradation is improved by dispersing water-soluble resin particles in a biodegradable resin. Polylactic acid or polybutylene sushi Although it is specifically disclosed to enzymatically degrade a composition consisting of nate and polyacrylic acid particles, there is no teaching about the degradation of PGA or PGA compositions with aqueous alkaline solutions.

JP 2002-344116 A JP 2009-62609 A JP-A-2-251419 JP-A-9-123290 JP 2004-168895 A

  An object of the present invention is to provide a PGA composition capable of decomposing and removing PGA in a short time by immersion in an alkaline aqueous solution, a resin molded product containing PGA formed by molding the composition, or a part of the resin molded product. An object of the present invention is to provide a molded body provided and a method for decomposing PGA contained in a resin molded product or molded body.

  As a result of intensive studies on the above problems, the present inventors have solved the above problems by making the configuration using PGA a PGA composition containing PGA and a water-soluble polymer or water-soluble oligomer. I found what I could do.

  That is, according to the present invention, a PGA composition comprising 100 parts by mass of PGA and 1 to 25 parts by mass of a water-soluble polymer or water-soluble oligomer is provided.

  According to the present invention, the following PGA compositions (1) to (3) are provided as embodiments.

(1) The PGA composition described above, wherein the PGA is PGA obtained by ring-opening polymerization of 70 to 100% by mass of glycolide and 30 to 0% by mass of another cyclic monomer.
(2) The PGA has a ratio (Mw / Mn) of (a) a weight average molecular weight (Mw) of 10,000 to 800,000, and (b) a weight average molecular weight (Mw) and a number average molecular weight (Mn). The molecular weight distribution represented is 1.5 to 4.0, (c) the terminal carboxyl group concentration is 0.1 to 300 eq / 10 ⁶ g, (d) the residual glycolide amount is 0.2% by mass or less, and (e ) The PGA composition having a 1% thermogravimetric decrease starting temperature of 210 ° C or higher.
(3) The PGA composition, wherein the water-soluble polymer or water-soluble oligomer is polyvinyl alcohol, polyalkylene glycol, polyacrylic acid or glycolic acid oligomer.

  Moreover, according to this invention, the resin molded product containing PGA formed from the said PGA composition is provided.

  Moreover, according to this invention, this molded object provided with the resin molded product containing said PGA in a part of molded object is provided.

According to this invention, the molded object of the following (1)-(3) is provided as an embodiment.
(1) The said molded object contains resin other than a metal or PGA in the part except the resin molded product containing PGA.
(2) The molded body, wherein the molded body is a three-dimensional molded body molded by an ink jet method.
(3) The molded body, wherein the molded body is an injection molded circuit component.

  Furthermore, according to the present invention, the resin molded product or molded body containing PGA is immersed in an alkaline aqueous solution having an alkali compound concentration of 2 to 15% by mass and a temperature of 20 to 95 ° C. for 10 seconds to 110 minutes. A method for decomposing PGA contained in an article or molded body is provided.

  Furthermore, according to the present invention, as an embodiment of the method for decomposing PGA, a resin molded article or molded body containing PGA is contacted with an aqueous medium at a temperature of 50 to 200 ° C. for 1 minute to 14 hours. There is provided a method for decomposing PGA contained in the resin molded article or molded article immersed in the alkaline aqueous solution.

  In the present invention, a PGA composition in which alkali decomposition is promoted is obtained by using a PGA composition containing 100 parts by mass of PGA and 1 to 25 parts by mass of a water-soluble polymer or a water-soluble oligomer. There is an effect that it is possible to shorten the time required for disassembling the PGA contained in the resin molded product, in particular, the PGA contained in the resin molded product provided with the resin molded product containing PGA as an auxiliary member. As a result, there is an effect that the decomposition of PGA can be made efficient, and materials other than PGA can be prevented from being corroded by contact with alkali.

  The present invention relates to a PGA composition containing 100 parts by mass of PGA and 1 to 25 parts by mass of a water-soluble polymer or water-soluble oligomer, and a resin molded product containing PGA formed by molding the PGA composition.

1. PGA (polyglycolic acid)
In the present invention, PGA is a homopolymer of glycolic acid consisting only of glycolic acid repeating units represented by the formula:-(O.CH ₂ .CO)-(glycolide (GL) which is a bimolecular cyclic ester of glycolic acid). In addition, a PGA copolymer containing 70 mol% or more of the glycolic acid repeating unit is included.

  Examples of comonomers that give a PGA copolymer together with glycolic acid monomers such as glycolide include ethylene oxalate (ie, 1,4-dioxane-2,3-dione), lactides, lactones, carbonates, and ethers. , Ether esters, amides and other cyclic monomers; lactic acid, 3-hydroxypropanoic acid, 3-hydroxybutanoic acid, 4-hydroxybutanoic acid, 6-hydroxycaproic acid and other hydroxycarboxylic acids or alkyl esters thereof; ethylene glycol A substantially equimolar mixture of an aliphatic diol such as 1,4-butanediol and an aliphatic dicarboxylic acid such as succinic acid or adipic acid or an alkyl ester thereof; or two or more of these Can do.

  In the present invention, the glycolic acid repeating unit in PGA is 70 mol% or more, preferably 80 mol% or more, more preferably 90 mol% or more, still more preferably 95 mol% or more, and particularly preferably 98 mol% or more. Most preferably, it is a substantially PGA homopolymer of 99 mol% or more. If this ratio is too small, the strength and degradability expected for PGA will be poor. The repeating unit other than the glycolic acid repeating unit is 30 mol% or less, preferably 20 mol% or less, more preferably 10 mol% or less, still more preferably 5 mol% or less, particularly preferably 2 mol% or less, and most preferably. Is used in a proportion of 1 mol% or less.

  In the present invention, PGA is preferably PGA obtained by polymerizing 70 to 100% by mass of glycolide and 30 to 0% by mass of the other comonomer described above in order to efficiently produce a desired high molecular weight polymer. Another comonomer may be a cyclic monomer between two molecules, or may be a mixture of both instead of a cyclic monomer, but a cyclic monomer is preferred. Hereinafter, PGA obtained by ring-opening polymerization of 70 to 100% by mass of glycolide and 30 to 0% by mass of other cyclic monomers will be described in detail.

[Glycolide]
Glycolide that forms PGA by ring-opening polymerization is a bimolecular cyclic ester of glycolic acid, which is a kind of hydroxycarboxylic acid. Although the manufacturing method of glycolide is not specifically limited, Generally, it can obtain by thermally depolymerizing a glycolic acid oligomer. As a depolymerization method for glycolic acid oligomers, for example, a melt depolymerization method, a solid phase depolymerization method, a solution depolymerization method, etc. can be adopted, and glycolide obtained as a cyclic condensate of chloroacetate should also be used. Can do. If desired, glycolide containing glycolic acid can be used up to 20% by mass of the glycolide amount.

  In the present invention, PGA may be formed by ring-opening polymerization of glycolide alone, but may also be formed by simultaneously ring-opening polymerization using another cyclic monomer as a copolymerization component. When forming a copolymer, the proportion of glycolide is 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 98% by mass or more. And most preferably a substantially PGA homopolymer of 99% by weight or more.

[Cyclic monomer]
Other cyclic monomers that can be used as a copolymerization component with glycolide include lactones (for example, β-propiolactone, β-butyrolactone, in addition to bimolecular cyclic esters of other hydroxycarboxylic acids such as lactide). Cyclic monomers such as pivalolactone, γ-butyrolactone, δ-valerolactone, β-methyl-δ-valerolactone, ε-caprolactone, trimethylene carbonate, 1,3-dioxane and the like can be used. Other preferable cyclic monomers are bimolecular cyclic esters of other hydroxycarboxylic acids. Examples of hydroxycarboxylic acids include L-lactic acid, D-lactic acid, α-hydroxybutyric acid, α-hydroxyisobutyric acid, α- Hydroxyvaleric acid, α-hydroxycaproic acid, α-hydroxyisocaproic acid, α-hydroxyheptanoic acid, α-hydroxyoctanoic acid, α-hydroxydecanoic acid, α-hydroxymyristic acid, α-hydroxystearic acid, and these Examples include alkyl-substituted products. Another particularly preferable cyclic monomer is lactide, which is a bimolecular cyclic ester of lactic acid, and may be any of L-form, D-form, racemate, and a mixture thereof.

  The other cyclic monomer is 30% by mass or less, preferably 20% by mass or less, more preferably 10% by mass or less, further preferably 5% by mass or less, particularly preferably 2% by mass or less, and most preferably 1% by mass. Used in the following proportions. By ring-opening copolymerization of glycolide and other cyclic monomers, the melting point of PGA (copolymer) is lowered to lower the processing temperature, and the crystallization speed is controlled to improve extrusion processability and stretch processability. can do. However, if the use ratio of these cyclic monomers is too large, the crystallinity of the formed PGA (copolymer) is impaired, and heat resistance, gas barrier properties, mechanical strength, and the like are lowered. In addition, when PGA is formed from glycolide 100 mass%, another cyclic monomer is 0 mass%, and this PGA is also included in the scope of the present invention.

(Ring-opening polymerization reaction)
The ring-opening polymerization or ring-opening copolymerization of glycolide (hereinafter sometimes collectively referred to as “ring-opening (co) polymerization”) is preferably carried out in the presence of a small amount of a catalyst. Although the catalyst is not particularly limited, for example, a tin-based compound such as tin halide (for example, tin dichloride, tin tetrachloride, etc.) or organic carboxylate (for example, tin octoate such as tin 2-ethylhexanoate). A titanium compound such as alkoxy titanate; an aluminum compound such as alkoxyaluminum; a zirconium compound such as zirconium acetylacetone; an antimony compound such as antimony halide and antimony oxide; The usage-amount of a catalyst is a mass ratio with respect to cyclic ester, Preferably it is 1-1000 ppm, More preferably, it is about 3-300 ppm.

  Glycolide usually contains a trace amount of water and a hydroxycarboxylic acid compound composed of glycolic acid and a linear glycolic acid oligomer as impurities. By adjusting the total proton concentration of these impurities to preferably 0.01 to 0.5 mol%, more preferably 0.02 to 0.4 mol%, particularly preferably 0.03 to 0.35 mol%. The physical properties such as melt viscosity and molecular weight of the produced PGA can be controlled. Adjustment of the total proton concentration can also be performed by adding water to the purified glycolide.

  The ring-opening (co) polymerization of glycolide may be bulk polymerization or solution polymerization, but in many cases, bulk polymerization is employed. In order to adjust the molecular weight, a higher alcohol such as lauryl alcohol or water can be used as the molecular weight regulator. Moreover, you may add polyhydric alcohols, such as glycerol, for a physical property improvement. There are various types of polymerization equipment for bulk polymerization, such as an extruder type, a vertical type with paddle blades, a vertical type with helical ribbon blades, a horizontal type such as an extruder type and a kneader type, an ampoule type, a plate type and a tubular type. The device can be selected as appropriate. Moreover, various reaction tanks can be used for solution polymerization.

  The polymerization temperature can be appropriately set according to the purpose within a range from 120 ° C. to 300 ° C. which is a substantial polymerization start temperature. The polymerization temperature is preferably 130 to 270 ° C, more preferably 140 to 260 ° C, and particularly preferably 150 to 250 ° C. If the polymerization temperature is too low, the molecular weight distribution of the produced PGA tends to be wide. If the polymerization temperature is too high, the produced PGA is susceptible to thermal decomposition. The polymerization time is in the range of 3 minutes to 20 hours, preferably 5 minutes to 18 hours. If the polymerization time is too short, the polymerization does not proceed sufficiently and a predetermined weight average molecular weight cannot be realized. If the polymerization time is too long, the produced PGA tends to be colored.

  After making the produced PGA into a solid state, solid phase polymerization may be further carried out if desired. Solid-phase polymerization means an operation of heat treatment while maintaining a solid state by heating at a temperature lower than the melting point of PGA. By this solid phase polymerization, low molecular weight components such as unreacted monomers and oligomers are volatilized and removed. The solid phase polymerization is preferably performed for 1 to 100 hours, more preferably 2 to 50 hours, and particularly preferably 3 to 30 hours.

  Further, the crystallinity may be controlled by giving a thermal history to the solid PGA by a step of melting and kneading the PGA in a melting point Tm + 38 ° C. or higher, preferably within a temperature range from Tm + 38 ° C. to Tm + 100 ° C.

[Weight average molecular weight (Mw)]
The PGA in the present invention preferably has a weight average molecular weight (Mw) in the range of 10,000 to 800,000, more preferably 20,000 to 600,000, still more preferably 30,000 to 400,000. Particularly preferred are those in the range of 50,000 to 300,000. If the weight average molecular weight (Mw) is too small, the strength of the resin molded product containing PGA, particularly the strength of the resin molded product containing PGA as an auxiliary member may be insufficient. When the weight average molecular weight (Mw) is too large, it becomes difficult to obtain an easily decomposable PGA composition that can decompose and remove PGA in a short time. When it takes a long time to decompose PGA, in particular, a resin molded product containing PGA is provided in a part of the molded product, and a molded product containing a resin other than a metal or PGA in a portion excluding the resin molded product containing PGA, When PGA is decomposed and removed, deterioration due to contact with an alkaline aqueous solution may be unavoidable.

[Molecular weight distribution (Mw / Mn)]
In the present invention, the molecular weight distribution (Mw / Mn) represented by the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of PGA is within the range of 1.5 to 4.0. By reducing the amount of the polymer component in the low molecular weight region that is susceptible to degradation at an early stage or the amount of the polymer component in the high molecular weight region that is slow in degradation rate, the degradation rate can be controlled, which is preferable. If the molecular weight distribution is too large, the decomposition rate does not depend on the weight average molecular weight (Mw) of PGA, and its control may be difficult. If the molecular weight distribution is too small, it may be difficult to maintain the strength of the molded article containing PGA for a required period. The molecular weight distribution is preferably 1.6 to 3.7, more preferably 1.65 to 3.5.

[Terminal carboxyl group concentration]
In the present invention, the terminal carboxyl group concentration of PGA is preferably 0.1 to 300 eq / 10 ⁶ g, more preferably 1 to 250 eq / 10 ⁶ g, still more preferably ^{6 to} 200 eq / 10 ⁶ g, particularly preferably. By setting it as 12-75eq / 10 < ⁶ > g, the decomposition | disassembly performance of PGA can be adjusted to the optimal grade. That is, a carboxyl group and a hydroxyl group exist in the molecule of PGA. Among these, the concentration of the carboxyl group at the molecular end, that is, the terminal carboxyl group concentration is too low, the hydrolyzability is too low, the PGA decomposition rate decreases, and PGA can be decomposed and removed in a short time. It becomes difficult to obtain a readily degradable PGA composition. On the other hand, if the terminal carboxyl group concentration is too large, the hydrolysis of PGA progresses quickly, so that the excellent performance of PGA such as mechanical strength cannot be exhibited over a long period of time, and the initial strength of PGA Is low, the strength is reduced rapidly. In order to adjust the terminal carboxyl group concentration, for example, when polymerizing PGA, a method such as changing the type or addition amount of the catalyst or molecular weight regulator may be used.

[Amount of residual glycolide]
In the present invention, the amount of residual glycolide of PGA is preferably 0.2% by mass or less, more preferably 0.15% by mass or less, and particularly preferably 0.12% by mass or less, whereby melt molding processing or It is possible to suppress the molecular weight of PGA from being lowered during other processing and to improve water resistance. For this purpose, for example, when polymerizing PGA, at the end of the polymerization (preferably at a monomer conversion of 50% or more), the polymerization temperature is below 200 ° C. so that the system is in solid phase. More preferably, the temperature is adjusted to 140 to 195 ° C., more preferably 160 to 190 ° C., and it is also preferable to subject the produced PGA to a step of desorbing and removing residual glycolide into the gas phase. When the amount of residual glycolide is too large, the molecular weight of PGA is lowered during molding or processing for forming a coating film, and performance cannot be exhibited over a long period of time.

[1% thermal weight reduction start temperature]
In the present invention, the 1% thermogravimetric decrease starting temperature of PGA is preferably 210 ° C. or higher, more preferably 213 ° C. or higher, and particularly preferably 215 ° C. or higher. It can suppress that molecular weight falls. The upper limit of the 1% thermogravimetric decrease starting temperature is usually 235 ° C, preferably 230 ° C. The 1% thermogravimetric decrease starting temperature is used as an indicator of the heat resistance of PGA. When PGA is heated at a rate of temperature increase from 50 ° C. to 2 ° C./min under a nitrogen stream at a flow rate of 10 ml / min, This is the temperature at which the weight loss rate from the weight of PGA at 50 ° C. (initial weight) becomes 1%. If the 1% thermogravimetric decrease start temperature of PGA is too low, the molecular weight of PGA is lowered during molding and other processing, and performance cannot be exhibited over a long period of time. In order to set the 1% thermogravimetric decrease starting temperature to 210 ° C. or higher, the amount of additives such as catalyst deactivator, crystal nucleating agent, plasticizer, and antioxidant should be minimized when polymerizing PGA. Or the like.

[Melting point (Tm)]
In the present invention, the melting point of PGA is 197 to 245 ° C., and it is preferable to adjust depending on the type and content ratio of the copolymer component. More preferably, it is 200-240 degreeC, More preferably, it is 205-235 degreeC, Most preferably, it is 210-230 degreeC. The melting point of the homopolymer of PGA is usually about 220 ° C. If the melting point is too low, the strength when molding or other processing is insufficient, or the temperature control when performing molding or the like becomes difficult. If the melting point is too high, molding processability may be insufficient or the flexibility of a molded product containing PGA may be insufficient.

2. Water-soluble polymer or water-soluble oligomer In the present invention, the water-soluble polymer is a resin having a solubility of at least 1 g per 100 g of water at room temperature and atmospheric pressure, and is not particularly limited. Examples of water-soluble polymers include polyalkylene glycols such as polyethylene glycol and polypropylene glycol, polyvinyl alcohol, polyacrylic acid, sodium polyacrylate, polyacrylamide, poly (N-isopropylacrylamide), and poly (N-vinyl-2). -Pyrrolidone), poly (2-hydroxyethyl methacrylate), polymaleic acid, polyacrylic acid / polymaleic acid copolymer, and the like. In view of the effect of promoting easy degradability of PGA, polyvinyl alcohol, polyalkylene glycol, or polyacrylic acid is particularly preferable. One type or two or more types of water-soluble polymers can be used.

  In the present invention, the water-soluble oligomer is an oligomer having a solubility of at least 1 g per 100 g of water at room temperature and atmospheric pressure, and the type and number of repeating units are not particularly limited. Examples of water-soluble oligomers include glycolic acid oligomers, lactic acid oligomers, alkylene glycol oligomers or derivatives thereof, acrylic acid oligomers, methacrylic acid oligomers or derivatives thereof, acrylamide oligomers or derivatives thereof, and saponified vinyl acetate oligomers or derivatives thereof. It is done. Particularly preferred is a glycolic acid oligomer in terms of the effect of promoting easy degradability of PGA, and an oligomer having a repeating unit number in the range of 3 to 20, more preferably 3 to 15, particularly preferably. It is an oligomer that is in the range of 4-10.

3. PGA composition The PGA composition of the present invention is a composition comprising 100 parts by mass of PGA and 1 to 25 parts by mass of the water-soluble polymer or water-soluble oligomer.

  The PGA composition of the present invention includes pellets, powders, granules and the like, sheets or films, rod-shaped, tube-shaped, block-shaped and other melt-formed bodies, containers, thermoformed products such as vacuum-formed products, fibers In addition, it does not have a specific shape, such as raw materials or additives in the fields of paints, coating agents, inks, toners, agricultural chemicals, pharmaceuticals, cosmetics, etc. Including those used for applications utilizing mechanical strength such as strength, it is not limited to a specific shape.

  The PGA composition of the present invention may further contain other resins and additives as long as the characteristics are not significantly impaired.

  Examples of the other resins include aliphatic polyesters such as polylactic acid, polybutylene succinate, polyethylene succinate, poly β-propiolactone, and polycaprolactone, and polyamides such as polyurethane and poly L-lysine.

  Additives include pigments, heat stabilizers, antioxidants, weathering agents, flame retardants, plasticizers, lubricants, mold release agents, antistatic agents, UV absorbers, colorants, crystallization accelerators, hydrogen ion concentration control Additives usually blended such as agents and fillers.

  As the heat stabilizer and the antioxidant, for example, hindered phenol, phosphorus compound, hindered amine, sulfur compound, copper compound, alkali metal halide or a mixture thereof can be used. These additives such as heat stabilizers, antioxidants and weathering agents are generally added during melt-kneading or polymerization. Inorganic fillers include talc, calcium carbonate, zinc carbonate, wollastonite, silica, alumina, magnesium oxide, calcium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, magnesium silicate, glass balloon, carbon black, Examples thereof include zinc oxide, antimony trioxide, zeolite, hydrotalcite, metal fiber, metal whisker, ceramic whisker, potassium titanate, boron nitride, graphite, glass fiber, and carbon fiber. Examples of the organic filler include naturally occurring polymers such as starch, cellulose fine particles, wood flour, okara, fir shell, bran, and modified products thereof.

  The blending amount of the water-soluble polymer or water-soluble oligomer in PGA is required to be 1 to 25 parts by mass, preferably 2 to 20 parts by mass, and 3 to 15 parts by mass with respect to 100 parts by mass of PGA. It is more preferable that When the amount of the water-soluble polymer or water-soluble oligomer is less than 1 part by mass, the effect of promoting the decomposition of PGA by the alkaline aqueous solution cannot be sufficiently obtained. On the other hand, when the amount of the water-soluble polymer or water-soluble oligomer exceeds 25 parts by mass, the excellent properties of PGA such as biodegradability, heat resistance and mechanical strength are not sufficiently exhibited.

  Examples of the method for producing the PGA composition of the present invention include a method of melt-kneading PGA and a water-soluble polymer or water-soluble oligomer, and the melt-kneader to be used is a general extruder such as a uniaxial screw. Examples thereof include an extruder, a twin screw extruder, a roll kneader, and a Brabender, and a twin screw extruder is preferable in order to improve the dispersion of the water-soluble polymer or water-soluble oligomer. As a method for adding the PGA and the water-soluble polymer or water-soluble oligomer to the kneader, pellet-form or powder-like PGA and the water-soluble polymer or water-soluble oligomer are dry-blended in advance before melt-kneading. And a method of supplying using a powder feeder is desirable.

The melt viscosity of the PGA composition of the present invention is preferably in the range of 20 to 200 Pa · s. If the melt viscosity of the PGA composition is too large, it may be difficult to mold a resin molded product containing PGA from the PGA composition. In particular, the PGA composition cannot flow uniformly during molding when trying to obtain a molded article having a relatively thin film-like PGA as in the case of manufacturing an injection molded circuit component. In some cases, it may be difficult to obtain a resin molded product containing PGA having a uniform composition. On the other hand, if the melt viscosity of the PGA composition is too small, the strength of the resin molded product containing PGA may be insufficient, or burrs may be generated during molding. The melt viscosity of the PGA composition of the present invention is more preferably in the range of 25 to 150 Pa · s, further preferably 30 to 100 Pa · s, and particularly preferably 35 to 80 Pa · s. The melt viscosity of the PGA composition or PGA is measured under conditions of a resin temperature of 230 ° C. and a shear rate of 100 sec ⁻¹ .

4). Resin Molded Article Containing PGA The PGA composition of the present invention can form a resin molded article containing PGA by a PGA molding method well known to those skilled in the art. The resin molded product containing PGA formed from the PGA composition of the present invention is easily decomposed by being immersed in an alkaline aqueous solution.

  The resin molded product containing PGA formed from the PGA composition of the present invention includes extrusion molding, injection molding, compression molding, injection compression molding, transfer molding, cast molding, stampable molding, blow molding, stretched film molding, inflation. In addition to molded products with specific shapes formed by melt molding or other molding methods such as film molding, laminate molding, calendar molding, foam molding, RIM molding, FRP molding, powder molding or paste molding, paints and coating agents Used in applications that take advantage of mechanical strength such as PGA degradability, heat resistance, and tensile strength, such as raw materials or additives in fields such as ink, toner, agricultural chemicals, pharmaceuticals, and cosmetics, etc. Means all that can be done.

5. Molded product comprising a resin molded product containing PGA in part The resin molded product containing PGA is a part of the molded product, in addition to the resin molded product containing the PGA used alone, formed from the PGA composition of the present invention. A molded article comprising a member made of a resin molded article containing PGA formed from the PGA composition, and a member other than the resin molded article containing PGA in a portion of the molded article excluding the resin molded article containing PGA. Can also be used. If a molded article that includes a PGA-containing resin molded article formed from the PGA composition of the present invention is immersed in an alkaline aqueous solution, the resin molded article containing the PGA will be immersed in the alkaline aqueous solution. PGA can be decomposed and removed.

  Although it does not specifically limit as a molded object provided with the resin molded product containing PGA formed from the PGA composition of this invention in a part of molded object, The following are included.

  For example, there is an injection molded circuit component in which an electric circuit or an electrode is formed on the molded circuit component previously described in Patent Document 2, that is, an injection molded product which is a base formed by injection molding of a thermoplastic resin. In the process of producing an injection molded circuit component using the PGA composition of the present invention, the coating material formed from the PGA composition of the present invention corresponds to a resin molded product containing PGA, and is formed from the PGA composition. The coating material to be formed may be formed on the surface of a part of the substrate, and thereafter (after electroless plating), the coating material made of the PGA composition of the present invention may be removed. Here, in order to provide a coating material formed of PGA on a part of a substrate which is an injection molded product, the substrate having a roughened surface is set in an injection mold, and the PGA composition of the present invention is used. A method of injecting a material containing s into the cavity can be employed.

  Furthermore, as a molded body provided with a resin molded product formed from the PGA composition of the present invention in a part of the molded body, it is formed by an inkjet method injecting a liquid or powdery resin previously described in Patent Document 4. And other three-dimensional laminate molded products formed by a powder lamination method using metal, ceramic or resin powder. These auxiliary members of the three-dimensional laminated molded product correspond to a resin molded product containing PGA formed from the PGA composition of the present invention. In order to form a resin molded article containing PGA from the PGA composition of the present invention as an auxiliary member of these three-dimensional laminated molded articles, a low melting point powder composed of the PGA composition of the present invention is applied to a predetermined portion by an inkjet method. There is a method of spraying.

  A molded body provided with a resin molded article containing PGA formed from the PGA composition of the present invention in a part of these molded articles is a part other than a metal or PGA in a part excluding the resin molded article containing the PGA. The resin can be included.

  Examples of the metal include iron, copper, aluminum, magnesium, brass, nickel and the like. Examples of resins other than PGA include polyvinyl chloride, polyvinylidene chloride, polyolefins such as polyethylene and polypropylene, polystyrene, ABS, polyamide, acrylic resin, polyacetal, polycarbonate, polyester, polyphenylene sulfide, and polyether ether ketone. When these metals and resins other than PGA have low alkali resistance, deterioration may occur when the molded body is treated with an aqueous alkaline solution to decompose PGA. If it is a molded body provided with a resin molded product containing PGA formed from the PGA composition of the present invention in a part of the molded body, PGA can be decomposed in a short time, so that deterioration of metals, resins other than PGA, etc. Does not occur.

6). Decomposition of PGA contained in resin molded article or molded article (1) Immersion in alkaline aqueous solution The method for decomposing PGA contained in a resin molded article containing PGA formed from the PGA composition of the present invention has an alkali compound concentration of 2 Alkaline decomposition is performed by immersing the resin molded product or molded body containing the PGA in an alkaline aqueous solution of 15% by mass and a temperature of 20 to 95 ° C. for 10 seconds to 110 minutes.

  Examples of the alkaline aqueous solution include an aqueous solution of an alkali compound which is an alkali metal hydroxide (so-called caustic alkali) or an alkaline earth metal hydroxide. Specific examples include an aqueous solution of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, calcium hydroxide, or strontium hydroxide, and an aqueous solution of sodium hydroxide or potassium hydroxide is preferable as the alkaline aqueous solution. Used.

  The density | concentration of the alkali compound of the alkaline aqueous solution which immerses the resin molded product or molded object containing PGA is 2-15 mass%. If the concentration of the alkali compound is too low, the decomposition and removal of PGA becomes insufficient, and the time required for the alkali decomposition of PGA cannot be shortened. As a result, the deterioration of materials with low alkali resistance other than PGA is suppressed. There are things you can't do. If the concentration of the alkali compound is too high, materials with low alkali resistance other than PGA may be corroded by alkali. The concentration of the alkali compound in the alkaline aqueous solution is preferably 3 to 13% by mass, more preferably 4 to 12% by mass, and still more preferably 5 to 11% by mass.

  The temperature of the alkaline aqueous solution in which the resin molded product or molded body containing PGA is immersed is 20 to 95 ° C. If the temperature of the aqueous alkali solution is too low, the time required for alkali decomposition of PGA cannot be shortened, and deterioration of materials with low alkali resistance other than PGA may not be suppressed. If the temperature of the aqueous alkali solution is too high, materials with low alkali resistance other than PGA may be corroded by alkali. The temperature of the alkaline aqueous solution is preferably 30 to 93 ° C, more preferably 40 to 90 ° C, still more preferably 50 to 88 ° C, and particularly preferably 60 to 85 ° C.

  The time for immersing the resin molded product or molded body containing PGA in the aqueous alkali solution is required to be immersed for 10 seconds to 110 minutes, depending on the concentration of the alkaline compound in the aqueous alkaline solution and the temperature of the aqueous alkaline solution. If the time for immersing the resin molded product or molded product containing PGA in an alkaline aqueous solution is too short, decomposition and removal of PGA may be insufficient. If the time of immersion in the alkaline aqueous solution is too long, materials having low alkali resistance other than PGA may be corroded by alkali. The time for immersing the resin molded product containing PGA in the alkaline aqueous solution is preferably 1 to 105 minutes, more preferably 5 to 100 minutes, still more preferably 10 to 95 minutes, and particularly preferably 1 to 18 minutes.

  As a method of immersing a resin molded product or molded product containing PGA in an alkaline aqueous solution, in addition to a so-called soaking method in which a resin molded product or molded product containing PGA is completely immersed in an alkaline aqueous solution, spraying or flowing down the alkaline aqueous solution A resin molded article containing PGA or a method of covering the entire surface of the molded article with an alkaline aqueous solution, and in particular, in the molded article provided with a resin molded article containing PGA in a part of the molded article, a resin formed from the PGA For example, a method in which the molded article is immersed in an aqueous alkaline solution so that the portion excluding the member formed from PGA is prevented from coming into contact with the aqueous alkaline solution as much as possible.

(2) Contact with aqueous medium In the method for decomposing PGA of the present invention, alkali decomposition is performed by immersing in an alkaline aqueous solution having an alkali compound concentration of 2 to 15 mass% and a temperature of 20 to 95 ° C. for 10 seconds to 110 minutes. The resin molded article or molded body containing PGA is immersed in an aqueous medium at a temperature of 50 to 200 ° C. for 1 minute to 14 prior to immersing the resin molded article or molded body containing PGA in an alkaline aqueous solution. It is preferable to immerse in aqueous alkali solution after contacting for a time. The aqueous medium having a temperature of 50 to 200 ° C. is heated water, that is, warm water, pressurized water heated to 100 ° C. or higher, or steam heated to 100 ° C. or higher. Accordingly, the contact with the aqueous medium may be performed by contacting with warm water, pressurized water, or steam. In addition, a method of immersing in warm water or pressurized water after performing a steam treatment or a method of performing steam treatment after immersing in warm water or pressurized water may be used, but immersion in warm water after performing steam treatment The method of performing is preferable. Since the PGA-hydrolysis proceeds moderately by bringing the resin molded article or molded body containing PGA into contact with an aqueous medium at a temperature of 50 to 200 ° C. for 1 minute to 14 hours before immersing in an alkaline aqueous solution. The immersion in an alkaline aqueous solution for the purpose of decomposing and removing the solution is short. As a result, the time for decomposing and removing the PGA-containing resin molded product or the PGA contained in the molded product is shortened. In particular, in the molded product comprising the PGA-containing resin molded product as an auxiliary member in a part thereof, the PGA The material with low alkali resistance in the part excluding the resin molded product containing, requires less time for contact with the alkaline aqueous solution, so it does not erode or contaminate the material with low alkali resistance. Only the auxiliary member that is a resin molded product containing unnecessary PGA can be quickly disassembled and removed.

  The aqueous medium to be brought into contact with the resin molded product or molded body containing PGA needs to contain no inorganic salt, and examples thereof include distilled water, ion-exchanged water, and deionized water.

  When the temperature of the aqueous medium brought into contact with the resin molded product or molded product containing PGA is less than 50 ° C., hydrolysis of PGA hardly proceeds, so that the immersion in an alkaline aqueous solution for decomposing PGA is short. The effect of time may not be obtained, and deterioration of materials with low alkali resistance other than PGA cannot be suppressed. When the temperature of the aqueous medium brought into contact with the resin molded product or molded body containing PGA exceeds 200 ° C., materials other than PGA may swell or thermally decompose in a high-temperature aqueous medium. Strict management and adjustment of the hydrolysis rate may be difficult. Moreover, since a high pressure is required for the treatment at a temperature exceeding 200 ° C., economical efficiency such as an increase in the size of the apparatus may be lacking.

  When using hot water, the temperature range of the aqueous medium brought into contact with the resin molded article or molded article containing PGA is preferably 55 to 98 ° C, more preferably 60 to 95 ° C, still more preferably 62 to 93 ° C, Especially preferably, it is 65-90 degreeC. When using pressurized water, Preferably it is 100-130 degreeC, More preferably, it is 101-125 degreeC, More preferably, it is 102-120 degreeC, Most preferably, it is 103-115 degreeC. When using steam, it is preferably 102 to 180 ° C, more preferably 105 to 170 ° C, still more preferably 108 to 160 ° C, and particularly preferably 110 to 150 ° C.

  Since the hydrolysis of PGA hardly proceeds when the time during which the resin molded product or molded body containing PGA is brought into contact with an aqueous medium having a temperature of 50 to 200 ° C. is less than 1 minute, the aqueous alkaline solution is used to decompose PGA. In some cases, it is impossible to immerse the material in a short time, and it is impossible to suppress deterioration of materials having low alkali resistance other than PGA. If the contact time with the aqueous medium exceeds 14 hours, the total immersion time of the contact time with the aqueous medium and the immersion time in the alkaline aqueous solution becomes excessively long, and materials other than PGA are used. May swell with water and deteriorate with subsequent aqueous alkaline solutions.

  The preferred range of the time for contacting the resin molded article or molded article containing PGA with an aqueous medium at a temperature of 50 to 200 ° C. depends on the alkali concentration of the alkaline aqueous solution and the immersion time in the alkaline aqueous solution, but it is 5 minutes to 13 hours. More preferably, it is between 10 minutes and 12, more preferably between 20 minutes and 11 hours. When pressurized water or steam is used as the aqueous medium, it is particularly preferably 25 minutes to 5 hours, most preferably 30 minutes to 3 hours.

  As a method of contacting with an aqueous medium at a temperature of 50 to 200 ° C., a resin molded article or molded article containing PGA is completely submerged in water, so-called immersion dipping method, or water is sprayed or flowed down to cause PGA. A method of covering the entire surface of a resin molded product or a molded body with water, and in particular, in the molded body having a resin molded product formed of PGA on at least a part of the molded body, resin molding formed of the PGA A dipping method or the like in which only a product is submerged in water can be employed. When steam is used as an aqueous medium, a resin molded product or molded body containing PGA is placed as it is or in an appropriate open container and placed in a heating and pressing apparatus such as an autoclave, and steam at a predetermined temperature is used. Thus, a method of performing steam processing for a predetermined time can be employed.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.

  The methods for measuring the physical properties and characteristics of PGA, PGA compositions, and resin molded articles or molded articles containing PGA in Examples and Comparative Examples, and the method for determining the decomposition state of PGA with an alkaline aqueous solution are as follows.

(1) Weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn):
The weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn) of PGA were measured using a gel permeation chromatography (GPC) analyzer under the following conditions.

  Sodium hexafluoroacetate (manufactured by Kanto Chemical Co., Ltd.) is added to hexafluoroisopropanol (used after distilling a product manufactured by Central Glass Co., Ltd.) and dissolved to prepare a 5 mM sodium trifluoroacetate salt solvent (A). To do.

  The solvent (A) was allowed to flow through a column (HFIP-LG + HFIP-806M × 2: SHODEX (registered trademark) manufactured by Showa Denko KK) at a flow rate of 1 ml / min at 40 ° C., and the molecular weights were 827,000, 1010,000, 10 mg each of 5 molecular weight polymethyl methacrylates (manufactured by POLYMER LABORATORIES Ltd.) having a molecular weight of 34,000, 1 million, and 20,000 and 10 ml of the solvent (A), of which 100 μl Is passed through the column, and the detection peak time by refractive index (RI) detection is obtained. A calibration curve of molecular weight is created by plotting detection peak times and molecular weights of five standard samples.

  Next, the solvent (A) is added to 10 mg of the sample PGA to make a 10 ml solution, and 100 μl of the solution is passed through the column. From the elution curve, the weight average molecular weight (Mw), the number average molecular weight (Mn), and the molecular weight Distribution (Mw / Mn) is determined. For the calculation, C-R4AGPC program Ver1.2 manufactured by Shimadzu Corporation was used.

(2) Terminal carboxyl group concentration The terminal carboxyl group concentration of PGA was measured by heating about 300 mg of PGA at 150 ° C. for about 3 minutes to completely dissolve in 10 ml of dimethyl sulfoxide, and cooling to room temperature. 2 drops of 1% by weight bromothymol blue / alcohol solution), and then 0.02N sodium hydroxide / benzyl alcohol solution was added, and the point at which the color of the solution changed from yellow to green visually was the end point. It was. The terminal carboxyl group concentration was calculated as the equivalent per 1 ton (10 ⁶ g) of PGA from the amount dropped at that time.

(3) Residual glycolide content The amount of residual glycolide in PGA was measured by adding 2 g of dimethyl sulfoxide containing 0.2 g / l of the internal standard substance 4-chlorobenzophenone to about 100 mg of PGA, and heating at 150 ° C. for about 5 minutes. Then, the solution is dissolved, cooled to room temperature, and then filtered. 1 μl of the solution was sampled and injected into a gas chromatography (GC) apparatus for measurement. From the numerical value obtained by this measurement, the amount of glycolide was calculated as mass% contained in PGA. The GC analysis conditions are as follows.

Apparatus: “GC-2010” manufactured by Shimadzu Corporation
Column: “TC-17” (0.25 mmφ × 30 m)
Column temperature: After holding at 150 ° C. for 5 minutes, the temperature is raised to 270 ° C. at 20 ° C./minute and held at 270 ° C. for 3 minutes.
Vaporization chamber temperature: 180 ° C
Detector: FID (hydrogen flame ionization detector), temperature: 300 ° C.

(4) 1% thermogravimetric decrease start temperature The 1% thermogravimetric decrease start temperature of PGA was measured by using a thermogravimetric measuring device TG50 manufactured by METTLER INC. And flowing nitrogen at a flow rate of 10 ml / min. Was heated from 50 ° C. at a rate of temperature increase of 2 ° C./min, and the weight loss rate was measured. With respect to the weight of the PGA at 50 ° C. (W50), the temperature when the weight is reduced by 1% is accurately read, and the temperature is set as the 1% thermal weight reduction start temperature of the PGA.

(5) Melting point (Tm)
The PGA melting point (Tm) was measured using a differential scanning calorimeter (DSC) manufactured by Shimadzu Corporation. About 10 mg of PGA sample was accurately weighed and increased from room temperature to 255 ° C at 10 ° C / min. This was performed by detecting an endothermic peak (melting point) appearing in the temperature rising process when heating.

(6) Melt Viscosity The measurement of the melt viscosity of the PGA composition or PGA is performed on a sample before being subjected to alkali decomposition by immersing in an alkaline aqueous solution (product name Flow Tester CFT-500D, manufactured by Shimadzu Corporation). / 100D), and the resin temperature was 230 ° C. and the shear rate was 100 sec ⁻¹ .

(7) Determination of the decomposition state of PGA by alkaline aqueous solution treatment The determination of the decomposition state of PGA by alkaline aqueous solution is performed by immersing a sample formed from PGA composition or PGA in alkaline aqueous solution, and the sample is completely dissolved in alkaline aqueous solution. By visually observing the disappearance, it was determined that the decomposition of PGA was completed. The immersion time in an alkaline aqueous solution until PGA was completely dissolved was measured.

[Reference Example] Synthesis of PGA [Synthesis of glycolide]
An aqueous glycolic acid solution having a concentration of 70% by mass was charged into a jacketed agitation tank, and the liquid in the can was heated to 200 ° C. to conduct a condensation reaction while distilling water out of the system. Next, low-boiling substances such as produced water and unreacted raw materials were distilled off while gradually reducing the internal pressure of the can to obtain a glycolic acid oligomer.

  The glycolic acid oligomer prepared above was charged into a reaction vessel, diethylene glycol dibutyl ether was added as a solvent, and octyltetraethylene glycol was further added as a solubilizer. The depolymerization reaction was performed under heating and reduced pressure to co-distill the produced glycolide and the solvent. The distillate was condensed by a double tube condenser in which hot water was circulated and received in a receiver. The condensate in the receiver was separated into two liquids, with the upper layer being a solvent and the lower layer being condensed to a glycolide layer. Liquid glycolide was extracted from the bottom of the receiver, and the resulting glycolide was purified using a tower-type purification apparatus. The recovered purified glycolide had a purity of 99.99% or more as determined by DSC measurement.

〔polymerization〕
22.5 kg of glycolide, 0.68 g (30 ppm) of tin dichloride dihydrate, and 1.49 g of water are added to a 56-liter container having a jacket structure and a sealable volume, and the total proton concentration is set to 0. It adjusted to 13 mol%. The container was sealed, and steam was circulated through the jacket while stirring, and the contents were heated to 100 ° C. to melt the contents to obtain a uniform liquid. While maintaining the temperature of the contents at 100 ° C., the contents were transferred to an apparatus consisting of a metal (SUS304) tube having an inner diameter of 24 mm. A heat medium oil at 170 ° C. was circulated and held for 7 hours for polymerization. After cooling the polymerization apparatus by cooling the heat medium oil circulated through the jacket, a lump of produced PGA was taken out. The yield was almost 100%. The lump was pulverized by a pulverizer. The obtained PGA had a weight average molecular weight (Mw) of 200,000, a molecular weight distribution (Mw / Mn) of 2.45, a terminal carboxyl group concentration of 37 eq / 10 ⁶ g, a residual glycolide amount of 0.07% by mass, 1 % Thermogravimetric decrease starting temperature was 217 ° C., melting point (Tm) was 221 ° C., and melt viscosity was 300 Pa · s.

[Example 1]
20φ having a nozzle diameter of 3 mm, 95 parts by mass of PGA produced by the above reference example, and 5 parts by mass of polyvinyl alcohol (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name Ecomatic; hereinafter sometimes referred to as “PVA”). The mixture was melt-kneaded with a twin-screw extruder (cylinder temperature: 240 to 270 ° C., nozzle temperature: 250 ° C.), extruded into a strand, and cut into a length of 3 mm to produce PGA composition pellets. A sheet having a thickness of 0.5 mm obtained by press-molding 100 mg of the PGA composition pellets was used as a PGA composition sample.

  The PGA composition sample was immersed in 50 ml of ion-exchanged water whose temperature was adjusted to 70 ° C. for 3 hours, and then the PGA composition sample was taken out and dried at 80 ° C. without adjusting the alkali compound concentration of 5% by mass. When the time until the PGA composition was alkali-decomposed and removed was measured by dipping in 50 ml of NaOH aqueous solution, the PGA composition disappeared in 75 minutes.

  In addition, when the weight average molecular weight (Mw) and the melt viscosity were measured for the PGA composition sample before being immersed in the NaOH aqueous solution, the weight average molecular weight (Mw) was 130,000, and the melt viscosity was 54 Pa · s. It was.

[Example 2]
PGA composition pellets were obtained in the same manner as in Example 1 except that 5 parts by mass of polyvinyl alcohol was changed to 5 parts by mass of polyethylene glycol (manufactured by Sigma-Aldrich, hereinafter referred to as “PEG”). Produced, PGA composition sample was obtained and alkali decomposed. The PGA composition disappeared in 105 minutes. In addition, the weight average molecular weight (Mw) of the PGA composition sample before alkali decomposition was 149,000, and the melt viscosity was 41 Pa · s.

Example 3
5 parts by weight of polyvinyl alcohol was changed to 10 parts by weight of a glycolic acid oligomer (manufactured by Kureha Co., Ltd., hereinafter sometimes referred to as “GAO”), and PGA was changed to 90 parts by weight, and the temperature was adjusted to 70 ° C. PGA composition pellets were produced in the same manner as in Example 1 except that immersion in 50 ml of ion-exchanged water was not performed, and a PGA composition sample was obtained and subjected to alkali decomposition. The PGA composition disappeared in 90 minutes. The PGA composition sample before alkali decomposition had a weight average molecular weight (Mw) of 100,000 and a melt viscosity of 44 Pa · s.

[Comparative Example 1]
PGA pellets were produced in the same manner as in Example 1 using only PGA without blending polyvinyl alcohol, and a PGA sample was obtained for alkali decomposition. PGA disappeared in 120 minutes. The PGA sample before alkali decomposition had a weight average molecular weight (Mw) of 100,000 and a melt viscosity of 81 Pa · s.

[Comparative Example 2]
The PGA sample was alkali-decomposed in the same manner as in Comparative Example 1 except that it was immersed in 50 ml of ion-exchanged water whose temperature was adjusted to 70 ° C. for 5 hours. PGA disappeared in 105 minutes. The PGA sample before alkali decomposition had a weight average molecular weight (Mw) of 80,000 and a melt viscosity of 19 Pa · s.

[Comparative Example 3]
The PGA sample was alkali-decomposed in the same manner as in Comparative Example 1 except that it was immersed in 50 ml of ion-exchanged water whose temperature was adjusted to 70 ° C. for 2 hours. PGA disappeared in 145 minutes. In addition, the weight average molecular weight (Mw) of the PGA sample before alkali decomposition was 150,000, and the melt viscosity was 256 Pa · s.

  The results of Examples 1 to 3 and Comparative Examples 1 to 3 are summarized in Table 1.

  From the results of Table 1, in Examples 1 to 3 as PGA compositions containing PGA and a water-soluble polymer (PVA or PEG), or PGA and a water-soluble oligomer (GAO), PGA is decomposed by an alkaline aqueous solution, It can be seen that the time to be removed (“disappearance time in NaOH aqueous solution” in the table) is shortened. In Examples 1 and 2, the PGA composition containing PGA and a water-soluble polymer had a lower molecular weight than Comparative Example 1 even when immersed in water at 70 ° C. for 3 hours. It was found that there is stability.

  On the other hand, in Comparative Examples 1 to 3 in which no water-soluble polymer or water-soluble oligomer was blended with PGA, it took a long time for PGA to be decomposed and removed by the aqueous alkali solution. Further, in Comparative Example 2 in which the PGA sample was immersed in water at 70 ° C. for 5 hours before the alkali decomposition treatment, since the molecular weight before the alkali decomposition was large, hydrolysis of PGA had already progressed by immersion in water. Although it is assumed that the PGA is decomposed and removed by the aqueous alkaline solution, the time required for the PGA to be decomposed and removed is estimated to be higher, for example, because the molecular weight and the melt viscosity before the alkaline decomposition are large. This was longer than Example 3 in which the PGA produced was subjected to alkali decomposition.

  From these facts, it was found that a PGA composition containing a predetermined amount of PGA and a water-soluble polymer or water-soluble oligomer has a remarkable effect that cannot be predicted by those skilled in the art.

  Since a PGA composition containing a predetermined amount of PGA and a water-soluble polymer or water-soluble oligomer can be decomposed with an alkaline aqueous solution in a short time, the decomposition treatment of a resin molded product containing PGA can be made efficient. it can. In addition, in a molded body including a resin molded product containing PGA in a part thereof, the resin molded product containing PGA can be decomposed and removed in a short time, and therefore other parts of the molded product, that is, PGA can be removed. It can prevent that the part except the resin molded product containing contains deteriorates. Therefore, it can be expected that the production efficiency of the three-dimensional molded body and injection molded circuit parts molded by the ink jet method can be improved and the quality thereof can be improved. large.

Claims (13)

  A polyglycolic acid composition comprising 100 parts by mass of polyglycolic acid and 1 to 25 parts by mass of a water-soluble polymer or water-soluble oligomer.   The polyglycolic acid composition according to claim 1, wherein the polyglycolic acid is polyglycolic acid obtained by ring-opening polymerization of 70 to 100% by mass of glycolide and 30 to 0% by mass of another cyclic monomer. The polyglycolic acid is represented by a ratio (Mw / Mn) of (a) weight average molecular weight (Mw) of 10,000 to 800,000, (b) weight average molecular weight (Mw) and number average molecular weight (Mn). Molecular weight distribution of 1.5 to 4.0, (c) terminal carboxyl group concentration of 0.1 to 300 eq / 10 ⁶ g, (d) residual glycolide content of 0.2% by mass or less, and (e) The polyglycolic acid composition according to claim 1 or 2, wherein the 1% thermal weight loss onset temperature is 210 ° C or higher.   The polyglycolic acid composition according to any one of claims 1 to 3, wherein the water-soluble polymer or water-soluble oligomer is polyvinyl alcohol, polyalkylene glycol, polyacrylic acid or glycolic acid oligomer.   The resin molded product containing the polyglycolic acid formed from the polyglycolic acid composition of any one of Claims 1 thru | or 4.   A molded article comprising a resin molded article containing the polyglycolic acid according to claim 5 in a part of the molded article.   The molded body according to claim 6, wherein the molded body contains a resin other than a metal or polyglycolic acid in a portion excluding a resin molded product containing polyglycolic acid.   The molded body according to claim 7, wherein the molded body is a three-dimensional molded body molded by an inkjet method.   The molded body according to claim 7, wherein the molded body is an injection molded circuit component.   The resin molded product according to claim 5, wherein the resin molded product containing polyglycolic acid is immersed in an alkaline aqueous solution having an alkali compound concentration of 2 to 15 mass% and a temperature of 20 to 95 ° C for 10 seconds to 110 minutes. Decomposition method of glycolic acid.   The method for decomposing polyglycolic acid contained in a resin-molded article according to claim 10, wherein the resin-molded article is brought into contact with an aqueous medium at a temperature of 50 to 200 ° C for 1 minute to 14 hours and then immersed in the alkaline aqueous solution. .   The poly contained in the molded body according to any one of claims 6 to 9, wherein the molded body is immersed in an alkaline aqueous solution having an alkali compound concentration of 2 to 15 mass% and a temperature of 20 to 95 ° C for 10 seconds to 110 minutes. Decomposition method of glycolic acid.   The method for decomposing a polyglycolic acid contained in a molded product according to claim 12, wherein the molded product is contacted with an aqueous medium at a temperature of 50 to 200 ° C for 1 minute to 14 hours and then immersed in the aqueous alkaline solution.