JP5231147B2 - Polyglycolic acid solidified extruded product and method for producing the same - Google Patents

Description

  The present invention relates to a polyglycolic acid-solidified extruded product and a method for producing the same, and more specifically, a polyglycolic acid-solidified extruded product that can be formed into a secondary molded product by machining such as cutting, drilling, and cutting, and It relates to the manufacturing method.

  A resin molded product having a three-dimensional shape or a complicated shape is generally molded by injection molding. According to injection molding, a molded product having a desired shape can be mass-produced. However, in order to produce a molded product requiring high dimensional accuracy by injection molding, an expensive mold having high dimensional accuracy is required. In addition, since the injection-molded product is easily deformed by shrinkage or residual stress after injection molding, it is necessary to precisely adjust the mold shape according to the shape of the molded product or the characteristics of the resin material. In injection molding, since the defect rate is high, the product is often expensive. Furthermore, in injection molding, it is difficult to form a molded product having a large thickness.

  Resin material is extruded to produce machining materials having various shapes such as flat plates, round bars, pipes, and odd-shaped products (sometimes called "cutting materials"). A method of forming a secondary molded article having a desired shape by performing machining such as cutting, drilling, and cutting is known. The machining method for machining materials does not require expensive molds, so that it is possible to manufacture molded products with a small production volume at a relatively low cost, to respond to frequent changes in the specifications of the molded products, and to improve dimensional accuracy. Advantages include that a high molding can be obtained and that a molding having a complicated shape and a large thickness that are not suitable for injection molding can be produced.

  However, any resin material or extruded product is not suitable for machining materials. For machining materials, for example, it is thick and excellent in machinability, has little residual stress, does not generate excessive deformation due to frictional heat generated during machining, and does not cause deformation or discoloration. It is required to satisfy high-level required characteristics such as being capable of processing.

  For machining of polymer materials, most of the processing methods used for metal materials are generally used as they are. Even if it is an extrusion molded product, a thin and highly flexible material such as a normal film, sheet, or tube is not suitable for machining such as cutting. Even if the extruded product has a shape such as a flat plate or round bar with a large thickness or diameter, the extruded product with excessive residual stress at the time of extrusion is easily deformed at the time of machining or after machining. It is difficult to obtain a high secondary molded product. Even extruded products with reduced residual stress are not suitable for machining materials if they are prone to cracking or cracking during machining such as cutting, drilling or cutting.

  In order to obtain a machining material having characteristics suitable for machining by extrusion molding, it is necessary to devise a selection of a resin material, an extrusion molding method, and the like. Therefore, conventionally, various proposals have been made on extrusion methods for producing extruded products suitable for machining materials using resin materials containing general-purpose resins and engineering plastics.

  For example, Japanese Patent Application Laid-Open No. 2005-226031 (Patent Document 1) discloses solidification extrusion molding of a resin composition containing engineering plastics such as polyether ether ketone, polyether imide, polyphenylene sulfide, polysulfone, polyether sulfone, and polycarbonate. Thus, a method of manufacturing a machining material is disclosed.

  On the other hand, biodegradable plastics are attracting attention as environmentally friendly polymer materials, and their applications are expanded to extrusions such as films and sheets, blow moldings such as bottles, and injection moldings. In recent years, there has been an increasing demand for application of biodegradable plastics to machining materials.

  However, most biodegradable plastics have low melting point, insufficient heat resistance, insufficient strength, hardness, flexibility, etc., and are extruded products with large thickness or diameter and small residual stress. It is difficult to form an extruded product suitable for machining, such as being difficult to mold.

  For example, a thick flat plate formed by extrusion molding of typical polylactic acid as a biodegradable plastic is too brittle to perform machining such as cutting and drilling. A thick extruded product obtained by solidifying and extruding polylactic acid has the same drawbacks.

  Polyglycolic acid is a biodegradable plastic excellent in toughness and gas barrier properties. For example, Japanese Patent No. 4073052 (Patent Document 2) discloses a method of forming polyglycolic acid into a sheet by extrusion molding. The sheet is excellent in tensile strength, elongation, gas barrier properties and the like. However, a thick extruded product obtained by extruding polyglycolic acid is not suitable for machining because it easily cracks during cutting or cutting. Polyglycolic acid can be formed into a thick solid extruded product by ordinary solidified extrusion, but the resulting solid extruded product is difficult to cut or break during cutting. There was a problem such as.

JP 2005-226031 A Japanese Patent No. 4073052

  An object of the present invention is to provide a polyglycolic acid solidified extruded product that can be formed into a secondary molded product by machining such as cutting, drilling, and cutting, and a method for producing the same.

  Polyglycolic acid has superior crystallinity in terms of tensile strength, tensile elongation, bending strength, flexural modulus, hardness, flexibility, heat resistance, etc., compared to other biodegradable plastics such as polylactic acid It is a resin and has a gas barrier property comparable to or exceeding that of a general-purpose gas barrier resin. Polyglycolic acid can be formed into a film or sheet by extrusion. If polyglycolic acid can be used to obtain a thick extruded product having properties suitable for machining materials, it can be used for new applications of polyglycolic acid and has excellent properties. A secondary molded product can be provided.

  However, when a normal extrusion molding method is applied to polyglycolic acid to produce a flat extruded product with a large thickness, the resulting extruded product lacks hardness, strength, flexibility, etc. It has been found that there is a problem that cracks are likely to occur during machining such as cutting, drilling and cutting.

  Polyglycolic acid can be formed into a thick solid extrusion using a solidification extrusion apparatus comprising an extrusion die attached to the tip of the extruder and a forming die having a passage connected to the passage of the extrusion die. it can. However, it has been found that the obtained solidified extruded product has problems such as being susceptible to cracking at the time of cutting and cracking due to heat treatment (annealing) after solidified extrusion molding. Furthermore, it has been found that when a polyglycolic acid containing an additive such as a colorant is used, a streak-like flow pattern tends to occur on the surface and / or cross section of the solidified extruded product.

  Accordingly, as a result of intensive studies to solve the above problems, the present inventors have selected the melt viscosity of polyglycolic acid, solidified extrusion molding conditions, etc., and pressed the solidified extrudate to determine the thickness of the solidified extrudate. It has been found that a method of increasing the density of the solidified extrudate by suppressing the expansion in the direction or the diameter direction is effective.

  More specifically, an extruded product having a large thickness or diameter is different from an extruded product having a small thickness such as a normal sheet, and is affected by expansion in the thickness direction when melt-extruded from an extrusion die at the tip of the extruder. Appears greatly. For example, it has been found that a plate having a large thickness obtained by normal extrusion molding (melt extrusion molding) or solid extrusion molding has a significantly reduced density due to expansion in the thickness direction. As a result, it is possible to obtain only a low-density flat plate whose density is significantly lower than the density of polyglycolic acid in a highly crystallized state. A low-density flat plate has low hardness and strength and low flexibility and cannot withstand machining. Other thick extrusions such as round bars other than flat plates have similar problems.

  In order to increase the density of the solidified extrudate, in addition to selecting the melt viscosity of the polyglycolic acid used and the solidification extrusion conditions, the solidified extrudate is used as the polyglycolic acid extrusion method. Pressurize and pull back while applying back pressure in the forming die direction. At that time, pressurization suppresses expansion in the thickness direction or diameter direction of the solidified extrudate, so that the density of the solidified extrudate falls within a specific range. As a result of adopting the method of enhancing, it has been found that a solidified extruded product satisfying the required characteristics suitable for a machining material can be obtained. The present invention has been completed based on these findings.

According to the present invention, it is formed from a resin material containing polyglycolic acid having a melt viscosity of 10 to 1,500 Pa · s measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ , and is 1.575 to 1.625 g / cm. density of ^3, and have a less than 100mm in thickness or diameter than 5 mm, and, polyglycolic acid solidified extrudate is provided which is a material for machining.

Further, according to the present invention, the following steps 1 to 4 are performed.
a) A resin material containing polyglycolic acid having a melt viscosity of 10 to 1,500 Pa · s measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ is supplied to an extruder, and the cylinder temperature of the extruder is 245 to 275. Step 1 of melt kneading at ° C;
b) Forming provided with a cooling means and a flow path in which the resin material melted by melt kneading from the extrusion die at the tip of the extruder communicates with the molten resin passage of the extrusion die and has a cross-sectional shape of the extruded product Extruding into the flow path of the die 2;
c) Step 3 of cooling and solidifying the molten extrudate made of a resin material in the flow path of the forming die and then extruding the solidified extrudate from the tip of the forming die; and d) the solidified extrudate. Is taken up while applying back pressure in the direction of the forming die, and at that time, the expansion in the thickness direction or the diameter direction of the solidified extrudate is suppressed by pressurization, and the density is 1.575 to 1.625 g. Step 4 of obtaining a polyglycolic acid-solidified extruded product having a thickness or diameter of 5 mm to 100 mm at / cm ³ ;
A process for producing a polyglycolic acid-solidified extruded product, which is a material for machining, is provided.

According to the present invention, a polyglycolic acid-solidified extruded product, which is a material for machining, which has a large thickness or diameter and can be formed into a secondary molded product by machining such as cutting, drilling, and cutting, and its production A method can be provided. According to the manufacturing method of the present invention, the residual stress is reduced, the hardness, the strength, the flexibility, etc. are excellent, the colorant such as carbon black is uniformly dispersed, and no streak-like flow pattern is generated. It is possible to provide a polyglycolic acid solidified extruded product, which is a material for machining , having various properties suitable for the above.

  The polyglycolic acid used in the present invention has the following formula (1)

It is a polymer containing the repeating unit represented by these. In the polymer, the ratio of the repeating unit represented by the formula (1) is usually 70% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more. When the ratio of the repeating unit represented by the formula (1) is less than 70% by mass, the toughness, crystallinity, heat resistance, hardness, gas barrier property and the like tend to decrease. In many cases, it is preferable to use a homopolymer of polyglycolic acid.

  Polyglycolic acid can be produced by condensation polymerization of glycolic acid or ring-opening polymerization of glycolide. The repeating unit other than the repeating unit represented by the formula (1) is preferably a repeating unit derived from a cyclic monomer such as ethylene oxalate, lactide, lactones, trimethylene carbonate, 1,3-dioxane, It is not limited to these.

  By introducing the repeating unit derived from the cyclic monomer at a ratio of 1% by mass or more, the melting temperature of the polyglycolic acid can be lowered and the processing temperature can be lowered, thereby reducing the thermal decomposition during the melt processing. be able to. Also, the extrusion rate can be improved by controlling the crystallization rate of polyglycolic acid by copolymerization. On the other hand, if the repeating unit derived from the cyclic monomer is too large, the crystallinity inherent to polyglycolic acid is impaired, and the toughness and heat resistance of the resulting solidified extruded product may be significantly reduced.

The polyglycolic acid used in the present invention is preferably a high molecular weight polymer. The melt viscosity of the polyglycolic acid used in the present invention measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ is 10 to 1,500 Pa · s, preferably 30 to 1,300 Pa · s, more preferably 50 to 1, 000 Pa · s, particularly preferably 70 to 900 Pa · s.

  If the melt viscosity of polyglycolic acid is too low, melt extrusion and solid extrusion molding become difficult, and the flexibility and toughness of the resulting solid extrusion molding are reduced, and cracking is likely to occur during machining. If the melt viscosity of polyglycolic acid is too low, cracks may occur during heat treatment (annealing) of the solidified extruded product. If the melt viscosity of the polyglycolic acid is too high, the polyglycolic acid is likely to be thermally deteriorated because it must be heated to a high temperature during melt extrusion.

  The resin material used in the present invention is a resin composition containing polyglycolic acid as a main component. The main component means that the content of polyglycolic acid is usually 70% by mass or more, preferably 80% by mass or more, and more preferably 90% by mass or more. Other components include thermoplastic resins other than polyglycolic acid, for example, other biodegradable plastics such as polylactic acid.

  The resin material used in the present invention may contain a colorant such as a dye or a pigment. By using a colorant, it is possible to obtain a polyglycolic acid-solidified extruded product that has a high-class feeling and is easy to cut. As the colorant, a pigment is preferable in terms of excellent heat resistance. As the pigment, pigments of various colors used in the technical field of synthetic resins, such as a yellow pigment, a red pigment, a white pigment, and a black pigment, can be used. Among these pigments, carbon black is particularly preferable. Examples of carbon black include acetylene black, oil furnace black, thermal black, and channel black.

  The resin material used in the present invention is preferably a polyglycolic acid composition containing 0.001 to 5% by mass of a colorant based on the total amount. The content ratio of the colorant is preferably 0.01 to 3% by mass, more preferably 0.05 to 2% by mass. The colorant can be melt-kneaded with polyglycolic acid, but if desired, a polyglycolic acid composition (masterbatch) having a high concentration of colorant is prepared, and this masterbatch is diluted with polyglycolic acid. A resin material having a desired colorant concentration can also be prepared. From the viewpoint of uniform dispersibility of the colorant, it is preferable to prepare a resin material in which polyglycolic acid and the colorant are melt-kneaded and pelletized.

  Various fillers can be blended in the resin material used in the present invention for the purpose of improving mechanical strength and heat resistance. Examples of the filler include inorganic fibers such as glass fiber, carbon fiber, asbestos fiber, silica fiber, alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber; stainless steel, aluminum And fibrous fillers such as metal fibrous materials such as titanium, steel, and genuine; high melting point organic fibrous materials such as polyamide, fluororesin, polyester resin, and acrylic resin.

  Examples of fillers include mica, silica, talc, alumina, kaolin, calcium sulfate, calcium carbonate, titanium oxide, ferrite, clay, glass powder, zinc oxide, nickel carbonate, iron oxide, quartz powder, magnesium carbonate, and barium sulfate. It is also possible to use granular or powder fillers.

  These fillers can be used alone or in combination of two or more. The filler may be treated with a sizing agent or a surface treatment agent as necessary. Examples of the sizing agent or the surface treatment agent include functional compounds such as epoxy compounds, isocyanate compounds, silane compounds, and titanate compounds. These compounds may be used after being subjected to surface treatment or sizing treatment on the filler in advance, or may be added simultaneously with the preparation of the resin composition.

  In the resin material used in the present invention, as other additives than the above, for example, impact modifiers, resin modifiers, mold corrosion inhibitors such as zinc carbonate and nickel carbonate, lubricants, thermosetting resins, oxidation Inhibitors, ultraviolet absorbers, nucleating agents such as boron nitride, flame retardants, and the like can be added as appropriate.

Polyglycolic acid solidified extrudate of the present invention, the formed resin material comprising polyglycolic acid, possess a density of 1.575~1.625g / cm ^3, and less than 100mm in thickness or diameter than 5mm And it is the polyglycolic acid solidified extrusion molding which is a raw material for machining .

The density of the polyglycolic acid-solidified extruded product is preferably 1.577 to 1.620 g / cm ³ , more preferably 1.578 to 1.615 g / cm ³ . This density is often between 1.580 and 1.610 g / cm ³ . If the density of the polyglycolic acid solidified extruded product is too low, the strength, hardness, toughness, flexibility and the like are lowered, and cracks are likely to occur during machining such as cutting, drilling and cutting. If the density of the polyglycolic acid-solidified extruded product is too high, it is difficult to produce.

  The thickness or diameter of the polyglycolic acid-solidified extruded product is 5 mm or more and 100 mm or less, preferably more than 5 mm and 100 mm or less, more preferably 8 to 90 mm, still more preferably 10 to 80 mm, and particularly preferably 15 to 70 mm. In many cases, it is possible to obtain a solidified extruded product having satisfactory machinability within the range of the thickness or diameter of 20 to 50 mm.

  If the thickness or diameter is too small, it becomes difficult to form a secondary molded product having a desired shape by machining such as cutting. For example, extrudates with a small thickness, such as films, sheets, and tubes, are generally low in rigidity and flexible, making mechanical drilling with drilling or drilling difficult or virtually impossible It is. A molded product having a thickness or diameter that is too small is difficult to form by solidified extrusion. The upper limit of thickness or diameter is generally 100 mm. If the thickness or diameter is too large, it will be difficult to sufficiently remove or reduce the residual stress even if the solidified extruded product is heat-treated. When a solidified extruded product having a large residual stress is machined, the resulting secondary molded product is likely to be deformed.

  The polyglycolic acid solidified extruded product of the present invention is preferably a flat plate or a round bar, and more preferably a flat plate in terms of easy solidification extrusion and subsequent densification treatment.

The polyglycolic acid-solidified extruded product, which is a material for machining according to the present invention, can be produced by a production method including the following steps 1 to 4.

a) A resin material containing polyglycolic acid having a melt viscosity of 10 to 1,500 Pa · s measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ is supplied to an extruder, and the cylinder temperature of the extruder is 245 to 275. Step 1 of melt kneading at ° C;
b) Forming provided with a cooling means and a flow path in which the resin material melted by melt kneading from the extrusion die at the tip of the extruder communicates with the molten resin passage of the extrusion die and has a cross-sectional shape of the extruded product Extruding into the flow path of the die 2;
c) Step 3 of cooling and solidifying the molten extrudate made of a resin material in the flow path of the forming die and then extruding the solidified extrudate from the tip of the forming die; and d) the solidified extrudate. Is taken up while applying back pressure in the direction of the forming die, and at that time, the expansion in the thickness direction or the diameter direction of the solidified extrudate is suppressed by pressurization, and the density is 1.575 to 1.625 g. Step 4 of obtaining a polyglycolic acid-solidified extruded product having a thickness or diameter of 5 mm or more and 100 mm or less at / cm ³ .

  A manufacturing process in the case where the polyglycolic acid-solidified extruded product of the present invention is a flat plate will be described with reference to FIG. In step 1, a resin material containing polyglycolic acid is put into the hopper of the extruder 1. Pellets are preferably used as the resin material. It is preferable that the resin material is sufficiently dried and dehumidified before molding. The dehumidifying and drying conditions are not particularly limited. For example, it is preferable to employ a method of holding the pellets at 100 to 160 ° C. for about 1 to 24 hours in a dry heat atmosphere.

  In the step 1, the resin material is melt-kneaded in the cylinder 3 of the extruder. The cylinder temperature is adjusted to 245 to 275 ° C, preferably 247 to 273 ° C, more preferably 250 to 270 ° C. When a plurality of heating means are arranged in the extruder cylinder corresponding to the solid phase resin transport section, the melting section, the liquid phase resin transport section, etc., the temperature of each heating means is made different from each other within the above range. Alternatively, the temperature of each heating means may be controlled to the same temperature.

  In step 2, the resin material melted by melt kneading is melt extruded from the extrusion die 4 at the tip of the extruder. The molten resin material from the extrusion die is extruded into the flow path of the forming die 5 provided with the flow path 6 having the cross-sectional shape of the extruded product and communicating with the molten resin passage of the extrusion die 4 and the cooling means 8. To do. The cross-sectional shape of the extrudate is a rectangle when the extrudate is a flat plate, and a circle when it is a round bar.

  In the step 3, the molten extrudate made of a resin material is cooled and solidified in the flow path 6 of the forming die 5, and then the solidified extrudate 11 is extruded from the tip of the forming die 5 to the outside. The extrusion speed is usually 10 to 30 mm / min, preferably 15 to 25 mm / min.

  In the step 3, a forming die in which the heating means 7 is arranged in addition to the cooling means 8 is used. First, the molten extrudate in the flow path 6 near the exit of the extrusion die 4 is converted to 230 to 280 ° C. by the heating means 7. It is preferable to employ a method of heating to a temperature of preferably 250 to 280 ° C. and then cooling the molten extrudate in the flow path to a temperature lower than the crystallization temperature of the polyglycolic acid by the cooling means 8 to solidify. preferable. When the temperature in the vicinity of the exit of the extrusion die 4 is rapidly cooled, the progress of crystallization of polyglycolic acid may be delayed. By heating the temperature in the vicinity of the extrusion die 4 to the above range and then cooling, the crystallization of the molten extrudate can be promoted. By setting the outlet temperature of the extrusion die 4 within the above range, the temperature of the molten extrudate in the flow path 6 near the outlet of the extrusion die 4 can be set within the above range.

  The temperature of the extrudate is cooled to a temperature lower than the crystallization temperature of polyglycolic acid by the cooling means and solidified. The crystallization temperature of polyglycolic acid (the crystallization temperature detected when the temperature is lowered from the molten state) is usually about 130 to 140 ° C. The cooling temperature of the cooling means 8 is preferably 100 ° C. or lower, more preferably 90 ° C. or lower. The lower limit of the cooling temperature is preferably 40 ° C, more preferably 50 ° C. When the resin material used in step 1 contains an additive component such as a colorant, the crystallization temperature of polyglycolic acid may increase due to melt-kneading in the cylinder of the extruder. The cooling temperature is preferably within the above range.

  The heating means 7 includes, for example, a heater 9 as a heating source. The cooling means 8 includes, for example, a water cooling pipe 10 that can circulate cooling water as a refrigerant.

In step 4, the solidified extrudate 11 is pressurized and taken out while applying a back pressure in the forming die direction. At that time, the expansion in the thickness direction or the diameter direction of the solidified extrudate is suppressed by pressurization, A polyglycolic acid solidified extruded product having a density of 1.575 to 1.625 g / cm ³ and a thickness or diameter of 5 mm to 100 mm is obtained. As the pressurizing means, for example, there is a combination of the upper roll group 12 and the lower roll group 13 shown in FIG. The solidified extrudate 11 can be pressurized by a method in which the lower roll group 13 is placed on a table and a load is applied to the upper roll group 12. The solidified extrudate 11 may be pressurized by a method in which a load in the upper direction is applied to the lower roll group 13 and a load in the lower direction is applied to the upper roll group 12.

  The thickness of the solidified extrudate is obtained by applying pressure to the solidified extrudate extruded from the forming die by the roll group 12 in which a plurality of rolls are combined from the discharge port of the forming die or the roll group 12 and the roll group 13. The expansion in the direction or the diameter direction can be suppressed, and the back pressure in the forming die direction can be applied. A back pressure in the forming die direction may be applied to the solidified extrudate 11 in combination with an appropriate loading means. The magnitude of the back pressure is usually 1,000 to 5,000 kg, preferably 1,500 to 4,000 kg. This back pressure can be measured as a die external pressure (pressure applied to the flow path 6).

This pressurization suppresses the expansion of the solidified extrudate in the thickness direction or the diameter direction, but the degree thereof is that the density of the finally obtained solid extrudate is 1.575 to 1.625 g / cm ^3. Within range. After pressing, the solidified extrudate is taken up in direction 14.

In the case where the solidified extruded product is a round bar, there is a method in which a group of rolls surrounding the round bar-shaped solidified extruded product is disposed, and a pressure in the center direction is applied to the group of rolls. The method of pressurizing the solidified extrudate discharged from the forming die can apply a back pressure in the direction of the forming die, suppresses the expansion of the solidified extrudate in the thickness direction or the diameter direction, and increases the density. Any method can be adopted as long as it is a method that can be within the range of 1.575 to 1.625 g / cm ³ .

  It is preferable that the polyglycolic acid extruded product obtained in the step 4 is annealed by arranging a step 5 of heat treatment at a temperature of 150 to 230 ° C. for 3 to 24 hours. By this annealing treatment, it is possible to remove the residual stress of the solidified extruded product, and to prevent inconvenience such as deformation in the solidified extruded product itself and the secondary molded product after machining. The heat treatment temperature is preferably 170 to 220 ° C, more preferably 180 to 210 ° C. The heat treatment time is preferably 4 to 20 hours, more preferably 5 to 15 hours.

  The polyglycolic acid-solidified extruded product of the present invention can have a shape such as a flat plate, a round bar, a pipe, and an irregular shape, but is preferably a flat plate or a round bar, and more preferably a flat plate. The flat plate can be easily densified by pressurization.

  Typical machining includes cutting, drilling, cutting, and combinations thereof. A broad-cutting method may include drilling as well as cutting. Cutting methods include turning using a single-edged tool, grinding, planing, and boring. Cutting methods using multiple blades include milling, drilling, threading, gear cutting, mold carving, and file processing. In the present invention, drilling using a drill or the like may be distinguished from cutting. Cutting methods include cutting with a blade (saw), cutting with abrasive grains, and cutting by heating and melting. In addition, a grinding finishing method, a plastic working method such as punching using a knife-like tool or scribing, and a special processing method such as laser processing can also be applied.

  When the polyglycolic acid solidified extrusion is a flat plate or round bar having a large thickness, generally, the solidified extrusion is cut into an appropriate size or thickness, and the cut solidified extrusion is ground to a desired shape. In addition, drill holes at the necessary locations. Finally, finish processing is performed if necessary. However, the order of machining is not limited to this. When the solidified extruded product is melted by frictional heat during machining and it is difficult to produce a smooth surface, it is desirable to perform machining while cooling the cutting surface. If the solidified extruded product excessively generates heat due to frictional heat, it causes deformation and coloring. Therefore, the solidified extruded product or the processed surface is preferably controlled to a temperature of 200 ° C. or lower, more preferably 150 ° C. or lower. .

  The polyglycolic acid-solidified extruded product of the present invention can be molded into secondary molded products such as various resin parts by performing machining such as cutting, drilling and cutting. Specific applications include, in the electric and electronic fields, wafer carriers, wafer cassettes, spin chucks, tote bins, wafer boats, IC chip trays, IC chip carriers, IC transfer tubes, IC test sockets, burn-in sockets, pin grid array sockets, Quad flat package, leadless chip carrier, dual inline package, small outline package, reel packing, various cases, storage tray, transport device parts, magnetic card reader, etc.

  In the field of OA equipment, various roll members in image forming apparatuses such as electrophotographic copying machines and electrostatic recording apparatuses, transfer drums for recording apparatuses, printed circuit board cassettes, bushes, paper and bill transport parts, paper feed rails, font cartridges, Ink ribbon canisters, guide pins, trays, rollers, gears, sprockets, computer housings, modem housings, monitor housings, CD-ROM housings, printer housings, connectors, computer slots, and the like.

  In the field of communication equipment, mobile phone parts, pagers, various sliding materials and the like can be mentioned. In the automotive field, interior materials, under hoods, electronic / electric equipment housings, gas tank caps, fuel filters, fuel line connectors, fuel line clips, fuel tanks, equipment beads, door handles, various parts and the like can be mentioned. In other fields, electric wire supports, radio wave absorbers, flooring materials, pallets, shoe soles, brushes, blower fans, planar heating elements, polyswitches, and the like can be given.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. The measurement methods of physical properties and characteristics are as follows.

(1) Melt Viscosity Using a sample obtained by crystallizing an amorphous sheet of polyglycolic acid having a thickness of about 0.2 mm at about 150 ° C. for 5 minutes, a nozzle-mounted capillograph with D = 0.5 mm and L = 5 mm [ Toyo Seiki Co., Ltd.] was used to measure the melt viscosity of the sample at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ .

(2) Density A sample cut out from the polyglycolic acid solidified extruded product was measured according to JIS R 7222 (pycnometer method using n-butanol).

[Example 1]
Polyglycolic acid having a melt viscosity of 700 Pa · s measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ and carbon black (acetylene black; Denka Black (registered trademark) manufactured by Denki Kagaku Kogyo) were melt-kneaded and pelletized. A resin material (carbon black concentration = 0.1% by mass) was dehumidified and dried at 140 ° C. for 6 hours.

  The dehumidified and dried pellets are supplied to a hopper of a 30 mmφ single-screw extruder with L / D = 20, melt kneaded at a cylinder temperature of 250 ° C., melt-extruded into a forming die flow path at an extrusion die outlet temperature of 275 ° C., and cooled. It was cooled and solidified at a temperature of 80 ° C. The extrusion speed was about 20 mm / 10 minutes.

  The solidified extruded product solidified in the flow path of the forming die is pressed between the upper roll group and the lower roll group to adjust the forming die external pressure (back pressure) to 3,000 kg, thereby The polyglycolic acid-solidified extruded product was densified. Next, the solidified extrusion was heat treated at 210 ° C. for 8 hours to remove residual stress. The heat treatment did not cause cracking or deformation in the solidified extruded product.

By this method, a flat polyglycolic acid solidified extruded product having a density of 1.593 g / cm ³ , a thickness of 20 mm, a width of 500 mm, and a length of 1,000 mm was obtained. When this flat plate was cut using a milling cutter, it could be cut without inducing cracks. The cut surface had no streak-like flow pattern due to insufficient kneading and was a uniform and beautiful cut surface. When this flat plate was drilled at a drill feed rate of 200 mm / min using a drill having a diameter of 800 μm, the drilling could be performed without generating cracks.

[Comparative Example 1]
A flat polyglycolic acid solidified extruded product was produced in the same manner as in Example 1 except that the solidified extrudate extruded from the forming die was not subjected to pressure treatment using the upper and lower roll groups.

The density of the obtained flat solidified extruded product was 1.560 g / cm ³ . This flat plate was deformed, for example, slightly wavy in the annealing process by heat treatment. When the flat plate was cut using a milling cutter, cracks occurred. A streak-like flow pattern was observed on the cut surface.

The polyglycolic acid solidified extruded product, which is a material for machining according to the present invention, has high processing accuracy and is suitable for molding secondary molded products such as various resin parts by machining. If desired, the polyglycolic acid-solidified extruded product of a flat plate or a round bar can be used for applications utilizing the characteristics of the material without machining or only by cutting and / or drilling.

It is explanatory drawing which shows an example of the solidification extrusion molding method used by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Extruder 2 Hopper 3 Cylinder 4 Extrusion die 5 Forming die 6 Flow path 7 Heating means 8 Cooling means 9 Heater 10 Water cooling pipe 11 Solidified extrudate 12 Upper roll group 13 Lower roll group 14 Taking-off direction

Claims (8)

It is formed from a resin material containing polyglycolic acid having a melt viscosity of 10 to 1,500 Pa · s measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ , a density of 1.575 to 1.625 g / cm ³ , and 5 mm. or 100mm have a thickness of less than or diameter, and polyglycolic acid solidified extrudate which is a material for machining.   The polyglycolic acid solidified extrudate according to claim 1, which has a shape of a flat plate or a round bar.   The polyglycolic acid solidified extruded product according to claim 1 or 2, wherein the resin material is a polyglycolic acid composition containing the polyglycolic acid and a colorant of 0.001 to 5% by mass based on the total amount. Steps 1 to 4 below
a) A resin material containing polyglycolic acid having a melt viscosity of 10 to 1,500 Pa · s measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ is supplied to an extruder, and the cylinder temperature of the extruder is 245 to 275. Step 1 of melt kneading at ° C;
b) Forming provided with a cooling means and a flow path in which the resin material melted by melt kneading from the extrusion die at the tip of the extruder communicates with the molten resin passage of the extrusion die and has a cross-sectional shape of the extruded product Extruding into the flow path of the die 2;
c) Step 3 of cooling and solidifying the molten extrudate made of a resin material in the flow path of the forming die and then extruding the solidified extrudate from the tip of the forming die; and d) the solidified extrudate. Is taken up while applying back pressure in the direction of the forming die, and at that time, the expansion in the thickness direction or the diameter direction of the solidified extrudate is suppressed by pressurization, and the density is 1.575 to 1.625 g. Step 4 of obtaining a polyglycolic acid-solidified extruded product having a thickness or diameter of 5 mm to 100 mm at / cm ³ ;
A process for producing a polyglycolic acid-solidified extruded product, which is a material for machining , comprising : In step 3, using a forming die in which a heating means is arranged in addition to a cooling means, first, the molten extrudate in the flow path near the exit of the extrusion die is heated to a temperature of 230 to 280 ° C. by the heating means, 5. The method according to claim 4 , wherein the molten extrudate in the flow path is then cooled to a temperature lower than the crystallization temperature of the polyglycolic acid and solidified by a cooling means. The manufacturing method of Claim 4 or 5 which further includes the process 5 which heat-processes the polyglycolic acid solidification extrusion molding obtained by the said process 4 at the temperature of 150-230 degreeC for 3 to 24 hours. The manufacturing method according to any one of claims 4 to 6 , wherein the resin material is a polyglycolic acid composition containing the polyglycolic acid and a colorant of 0.001 to 5% by mass based on the total amount. The manufacturing method according to any one of claims 4 to 7 , wherein in the step 4, a polyglycolic acid solidified extruded product having a shape of a flat plate or a round bar is obtained.

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