WO2017183379A1 - T-die, method for manufacturing same and releasability improving method - Google Patents

T-die, method for manufacturing same and releasability improving method Download PDF

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Publication number
WO2017183379A1
WO2017183379A1 PCT/JP2017/011483 JP2017011483W WO2017183379A1 WO 2017183379 A1 WO2017183379 A1 WO 2017183379A1 JP 2017011483 W JP2017011483 W JP 2017011483W WO 2017183379 A1 WO2017183379 A1 WO 2017183379A1
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Prior art keywords
die
molten resin
flow path
nitrogen
resin flow
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PCT/JP2017/011483
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French (fr)
Japanese (ja)
Inventor
植村　賢介
コンスタンチン シャルノフ
プルワディ　ラハルジョ
友子 重松
焼本　数利
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新明和工業株式会社
株式会社 日本製鋼所
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Publication of WO2017183379A1 publication Critical patent/WO2017183379A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/30—Extrusion nozzles or dies
    • B29C48/3001—Extrusion nozzles or dies characterised by the material or their manufacturing process
    • B29C48/3003—Materials, coating or lining therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/07—Flat, e.g. panels
    • B29C48/08—Flat, e.g. panels flexible, e.g. films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/30—Extrusion nozzles or dies
    • B29C48/305—Extrusion nozzles or dies having a wide opening, e.g. for forming sheets
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/36—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases using ionised gases, e.g. ionitriding

Definitions

  • the present invention relates to a T-die, a manufacturing method thereof, and a method for improving the release property of the molten resin with respect to the inner wall surface of the molten resin flow path and the surface of the lip portion inside the T-die.
  • the T die in the present invention include a T die having a slit-like discharge port, which is used for producing a film or sheet made of a thermoplastic resin material.
  • a method of extruding molten resin from the discharge port using a die having a slit-like discharge port called a T die is used.
  • a resin film for example, a film / sheet for optical resin
  • the die line means a stripe that is continuously generated in a specific position of the resin film corresponding to a specific position of the die along the extrusion direction of the resin film and is observable with the naked eye.
  • Patent Document 1 describes a T die in which a hard chromium plating layer is provided on the inner wall surface of a molten resin flow path (flowable material flow path).
  • Patent Document 2 discloses a T die coated with tungsten carbide.
  • Patent Document 3 describes that when resin waste adheres to the tip portion of the lip and accumulates, it becomes so-called “meani”, which adheres to the resin film and causes defective products.
  • Non-Patent Document 1 entitled “Surface carbonization and filling failure involving metal surface in injection molding of polybutylene terephthalate” includes defects such as surface carbonization phenomenon at the erased portion that occurs when plastic injection molding is performed.
  • the hard chrome plating may cause micro cracks (hair cracks) due to the difference in coefficient of linear expansion from the base material.
  • the molten resin is gradually deposited on the microcracks of the hard chromium plating layer provided on the inner wall surface of the molten resin flow path.
  • the molten resin gradually accumulates in the same manner on the dropped part. Then, the deposited molten resin is carbonized or oxidized, which generates a die line.
  • the lip portion has fine irregularities of 10 nm or more. In this case, it is considered that the molten resin enters, adheres, and is oxidized and deteriorated by contact with the atmosphere, thereby generating a die line.
  • the present inventor has intensively studied for the purpose of solving the above problems. Then, with respect to a conventional stainless steel T-die, nitrogen atoms are injected into the inner wall surface of the molten resin flow channel and the surface of the lip portion by a plasma nitriding method or the like, and the nitrogen atoms constitute the T-die.
  • a layer composed of a nitrogen-based intermetallic compound is formed on the surface by combining with an element (for example, iron or chromium), the layer is extremely excellent in releasability of the molten resin, has high hardness, and has a surface roughness. Since it was good, when the resin film was formed using the obtained T-die, it was found that a die line was extremely difficult to be formed over a long period of time, and the present invention was completed.
  • the present invention includes the following (1) to (6).
  • the manufacturing method of T-die with high hardness.
  • a stainless steel T-die for plastic molding that has a layer made of a nitrogen-based intermetallic compound on the inner wall surface of the molten resin flow path and the surface of the lip portion, and has excellent mold release properties and high hardness.
  • the T die according to (5) manufactured by the method of manufacturing a T die according to any one of (1) to (3) above.
  • the releasability of the molten resin with respect to the inner wall surface of the molten resin flow path and the surface of the lip portion is extremely high, the hardness is high, and the surface roughness is maintained at a low level.
  • rip part can be provided.
  • FIG. 3 is a graph showing the relationship between the temperature during plasma nitriding, the surface roughness Ra ( ⁇ m), and the hardness (HV Kgf / mm 2 ) obtained in an example.
  • the present invention relates to a method of manufacturing a stainless steel T die for plastic molding, which has a molten resin flow path inside and a lip portion at the discharge port, and plasma nitriding treatment is performed on an untreated T die.
  • a method for producing a T-die having excellent molten resin releasability and high hardness comprising a step of forming a layer made of a nitrogen-based intermetallic compound on the inner wall surface of the molten resin flow path and the surface of the lip portion. .
  • Such a method for producing a T-die having excellent mold releasability and high hardness is hereinafter also referred to as “the production method of the present invention”.
  • the present invention has a layer made of a nitrogen-based intermetallic compound on the inner wall surface of the molten resin flow path and the surface of the lip portion, and is excellent in the releasability of the molten resin and has high hardness, and is a stainless steel type for plastic molding T-die.
  • a stainless steel T-die for plastic molding that has excellent mold releasability and high hardness is hereinafter also referred to as “T-die of the present invention”.
  • the T-die of the present invention is preferably manufactured by the manufacturing method of the present invention.
  • FIG. 1 is a longitudinal sectional view of a preferred embodiment of the T die of the present invention
  • FIG. 2 is a side view showing an inner wall surface of a die body of the T die shown in FIG.
  • a T die 1 (T die 1) of the present invention has a die body 2 including a pair of die members 3 and 4.
  • a molten resin flow path 5 is formed between the die members 3 and 4. That is, the inner wall surfaces of the die members 3 and 4 constitute the molten resin flow path 5.
  • the molten resin flow path 5 has an inflow part 6, a manifold part 7, and a slit-like discharge part 8 in order from the upstream side.
  • a portion near the discharge port of the discharge portion 8 is a lip portion 9.
  • reference numerals 6 a, 7 a, and 8 a indicate wall surfaces of the die member 3 (4) in each of the inflow portion 6, the manifold portion 7, and the discharge portion 8.
  • a layer 20 (also referred to as a nitrogen-based intermetallic compound layer 20) made of a nitrogen-based intermetallic compound is formed on the inner wall surfaces of the die members 3 and 4 constituting the molten resin flow path 5 and the surface of the lip portion 9. ) Is formed.
  • the inflow portion 6 at the center in the longitudinal direction of the T-die 1 is connected to an extruder (not shown).
  • the molten resin is supplied into the molten resin flow path 5 from above.
  • the supplied molten resin flows into the manifold portion 7 having a substantially circular cross section extending in the longitudinal direction of the T die 1, spreads in the longitudinal direction of the T die 1, and then flows into the slit-like ejection portion 8. From the opening edge (discharge port) of the film, it is extruded on a roller (not shown) in the form of a film.
  • the shape of the T-die of the present invention is not particularly limited as long as it can be used for plastic molding of a film or the like, and may be the same shape as a conventionally known one.
  • the type of plastic to be molded such as a film is not particularly limited.
  • PMMA polymethyl methacrylate
  • PC polycarbonate
  • COP cycloolefin
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PAR Polyarylate
  • PI polyimide
  • PS polystyrene
  • PP polypropylene
  • PA polyamide
  • PA polyethylene
  • POM polyacetal
  • EVA ethylene-vinyl acetate copolymer resin
  • ABS styrene
  • PVC polyvinyl chloride
  • PPO polyphenylene oxide
  • the material of the die body provided in the T-die of the present invention is not particularly limited as long as it is stainless steel, and may be the same as that conventionally known, for example.
  • the nitrogen-based intermetallic compound layer of the T die of the present invention is composed of a nitrogen-based intermetallic compound formed by combining elements (for example, iron and chromium) constituting the die body and nitrogen, and this is a layered structure. It is.
  • the nitrogen-based intermetallic compound include Cr x N and Fe y N.
  • the nitrogen-based intermetallic compound layer is formed by injecting nitrogen atoms into the inner wall surface of the molten resin flow path and the surface of the lip portion in a conventionally known stainless steel T-die, so that the surface is coated as in plating In contrast, there is no strict boundary between the coating (nitrogen-based intermetallic compound layer) and the base material (die body).
  • a layer made of a nitrogen-based intermetallic compound is formed on the surface.
  • the inner side of the layer is a diffusion layer, and the inner side is a base material into which nitrogen does not enter.
  • the thickness of the nitrogen-based intermetallic compound layer is preferably approximately 10 to 50 ⁇ m, and more preferably 10 to 100 ⁇ m.
  • the T die of the present invention is formed by injecting nitrogen atoms into the inner wall surface of the molten resin flow path and the surface of the lip portion in a conventionally known stainless steel type T die. It is preferable to use plasma nitriding treatment. That is, the T die of the present invention is preferably manufactured by the manufacturing method of the present invention.
  • the plasma nitriding treatment may be a conventionally known one. For example, when a current is passed through a tungsten filament while injecting nitrogen gas, the nitrogen gas becomes a plasma state.
  • a negative bias is applied to an object to be plasma-nitrided (untreated T-die), nitrogen plasma (N + ) is targeted. It collides with the surface of the object (untreated T die) and is injected to produce Fe 4 N, Cr 4 N, or the like.
  • the filament current is 100 to 200 A
  • the discharge current is 100 to 300 A
  • the bias voltage for the object to be plasma-nitrided (untreated T-die) is 0.1 to 1000 V
  • the nitrogen pressure is 0.5 to 5 Pa and the treatment time are preferably 10 to 1000 minutes.
  • the bias voltage is preferably ⁇ 150 to ⁇ 400V. This is because the surface hardness is increased.
  • the temperature of the object to be treated (untreated T die) during the plasma nitriding treatment is preferably set to 250 to 350 ° C.
  • the temperature of the object to be processed (unprocessed T die) tends to increase as the magnitude of the bias voltage (absolute value of the negative bias voltage) is increased. Further, even if the time for which the bias voltage is continuously applied is lengthened, the temperature of the processing object (unprocessed T die) tends to increase similarly. Therefore, the temperature of the processing object (unprocessed T die) can be adjusted to a desired temperature by adjusting the magnitude of the bias voltage of the processing object (unprocessed T die) and the time for applying the bias voltage. it can.
  • the plasma nitriding treatment can be performed using a conventionally known apparatus.
  • a plasma ion implantation gun for performing plasma ion implantation processing by nitrogen plasma is installed in a vacuum chamber, and an untreated T die (which may be a conventionally known stainless steel T die) can be disposed at a position facing it.
  • An apparatus configured as described above can be used.
  • the method for improving releasability of the present invention is a method for improving the releasability of the molten resin with respect to the inner wall surface of the molten resin flow path inside the T die and the surface of the lip part.
  • the method includes a step of plasma nitriding the inner wall surface of the flow path and the surface of the lip portion to form a layer made of a nitrogen-based intermetallic compound.
  • a conventionally known stainless steel T die for plastic molding (that is, an untreated T die) is subjected to plasma nitriding treatment, and the inner wall surface of the molten resin channel and the surface of the lip portion And a step of forming a layer made of a nitrogen-based intermetallic compound.
  • the plasma nitriding method may be the same as the plasma nitriding treatment in the manufacturing method of the present invention described above.
  • Example 1 Steel pieces of steel types that can be used when manufacturing the T-die were prepared, and these were subjected to plasma nitriding treatment under various conditions to obtain test pieces. The test piece was subjected to a hardness measurement test, a surface roughness measurement test, and a releasability test using a cycloolefin polymer (COP) resin. This is specifically described below.
  • COP cycloolefin polymer
  • the steel slab is a steel for plastic molds having the composition shown in Table 1 below (made by UDDEHOLM, trade name: Stabux).
  • the size of the steel piece is 10 mm ⁇ 10 mm ⁇ thickness 2 mm.
  • the surface of the surface used is polished with abrasive grains and finished so that Ra is 0.005 ⁇ m (ISO 4287). .
  • the above steel pieces were subjected to plasma nitriding treatment under various conditions shown in Table 2 below to obtain test pieces.
  • plasma nitriding treatment trade name: PINK manufactured by Shin Meiwa Kogyo Co., Ltd. was used.
  • the hardness measurement test was performed based on the micro Vickers hardness test (indentation load 10 gf).
  • the surface roughness measurement test was performed by calculating the arithmetic average roughness (Ra) based on JIS B 0601.
  • the contact angle measured by the measurement procedure specifically shown below is large, when the COP resin is actually melted using a T die to produce a molded product of the COP resin, It can be judged that the releasability is high with respect to the surface.
  • the actual use atmosphere of the T-die is air, whereas the contact angle is measured in a nitrogen atmosphere. This is to evaluate the releasability from the basic resin on the metal surface after removing the influence of oxidation and carbonization. Although it is actually exposed to the atmosphere, the effects of carbonization and oxidation enter, and the characteristics of the metal surface itself cannot be grasped. Moreover, the influence of oxidation can be avoided to some extent by making the T die lip a nitrogen atmosphere.
  • the contact angle measurement procedure is as follows. [1] COP resin pellets were previously dried at 80 ° C. for 4 hours or more. [2] The test piece was loaded into an infrared heating furnace, COP resin pellets were placed on the surface thereof, and the temperature was raised from 25 ° C. (normal temperature) to 295 ° C. in 3 minutes in a nitrogen atmosphere. [3] After reaching 295 ° C., this temperature was maintained, and the contact angle was measured after 1 minute. For the measurement of the contact angle, a solid-liquid contact angle measuring device (WET-1200, manufactured by ULVAC-RIKO), which is a constant temperature wettability tester, was used. Based on this measurement result, the contact angle was calculated according to JIS R 3257 “Testing method for wettability of substrate glass surface”.
  • the test piece obtained by plasma nitriding treatment under various conditions by the above method was subjected to a hardness measurement test, a surface roughness measurement test, and a contact angle measurement. For comparison, a similar test was performed on a steel piece that was not plasma-nitrided.
  • FIG. 3 the photograph which shows the mode of a COP resin pellet when the inside of said solid-liquid contact angle measuring apparatus reaches
  • FIG. 4 is a graph in which the horizontal axis (X-axis) is temperature (° C.) (temperature when plasma nitriding is performed), and the vertical axis (Y-axis) is the contact angle (measurement result of COP resin contact angle at 295 ° C.). is there.
  • FIG. 4 shows the fact that the bias voltage is described in each measured value, and the contact angle cannot be explained only by the temperature.
  • the bias voltage value is 300 V and the temperature during plasma nitriding is 240 to 320 ° C.
  • the bias voltage value is 350 V and the plasma nitriding time is
  • the relationship between the temperature during plasma nitriding, the surface roughness Ra ( ⁇ m) and the hardness (HV Kgf / mm 2 ) was graphed. As shown in FIG.
  • the test piece subjected to the plasma nitriding treatment showed a contact angle of about 39 ° to more than 54 °, compared with 35 ° of the untreated steel piece. It was confirmed that it had a high contact angle.
  • the hardness of the untreated steel slab was HV550, whereas the hardness of the test specimen subjected to the plasma nitriding treatment increased to HV1300 at the maximum. Such an increase in hardness is thought to be because nitrogen atoms enter the steel by the plasma nitriding treatment to produce Cr 4 N, Fe 4 N intermetallic compounds.
  • the surface roughness of the test piece became rough compared with the case of the surface roughness of the untreated steel piece (Ra: 0.005), it is determined that the T die can be used practically.
  • Example 2 In test piece # 3 having a maximum treatment temperature of 350 ° C., slight coloring (considered as oxidation) occurred after storage in the atmosphere for about one month after the end of observation. This is presumably because the corrosion resistance of the steel material was slightly lost by the plasma nitriding treatment. If the corrosion resistance is significantly impaired, the commercial value is impaired. In consideration of this coloring, an accelerated test was carried out based on the Arrhenius equation, assuming 1-year atmospheric preservation. As a result, in the case of a test piece subjected to a plasma nitriding temperature of 320 ° C. or less, this coloring phenomenon was not observed.
  • the molten fine transfer (registered trademark) method in which the molten resin is applied to the mold while discharging the molten resin from the T die is performed using the T die of the present invention
  • the molten resin and the lip portion of the T die are used in the T die of the present invention. Since the releasability is improved, it is considered that a smooth coating surface property is realized, and the resin can be applied to a low temperature mold at a high speed.

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  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)

Abstract

The present invention addresses the problem of providing a method for manufacturing a T-die that does not cause a die line. The problem is solved by means of a method for manufacturing a stainless steel T-die for plastic molding, the T-die having a molten resin flow path therein and a lip part at an ejection port thereof, and having excellent molten resin releasability and high rigidity. The method comprises a step of subjecting an untreated T-die to plasma nitriding treatment to form a layer made of a nitrogen intermetallic compound on an inner wall surface of the molten resin flow path and on a surface of the lip part.

Description

Ｔダイ、その製造方法および離型性向上方法T-die, method for producing the same, and method for improving releasability
　本発明は、Ｔダイ、その製造方法およびＴダイ内部の溶融樹脂流路の内壁面およびリップ部の表面に対する溶融樹脂の離型性を向上させる方法に関する。本発明におけるＴダイとして、例えば、熱可塑性樹脂材料から構成されるフィルムやシートを製造するために用いられる、スリット状の吐出口を有するＴダイが挙げられる。 The present invention relates to a T-die, a manufacturing method thereof, and a method for improving the release property of the molten resin with respect to the inner wall surface of the molten resin flow path and the surface of the lip portion inside the T-die. Examples of the T die in the present invention include a T die having a slit-like discharge port, which is used for producing a film or sheet made of a thermoplastic resin material.
　環状ポリオレフィン、ポリブチレンテレフタレートなど樹脂フィルムの製造には、その形状からＴダイと呼ばれるスリット状の吐出口を有する口金を用いて該吐出口から溶融した樹脂を押し出す方法が用いられる。
　このような樹脂フィルム（例えば光学用樹脂用フィルム・シート）には、その表面にダイラインが発生してないことが要求される。ダイラインとは、ダイの特定の位置に対応する樹脂フィルムの特定位置に、樹脂フィルムの押出方向に沿って連続的に発生する、肉眼で観察可能な縞を意味する。 For the production of resin films such as cyclic polyolefin and polybutylene terephthalate, a method of extruding molten resin from the discharge port using a die having a slit-like discharge port called a T die is used.
Such a resin film (for example, a film / sheet for optical resin) is required to have no die line on its surface. The die line means a stripe that is continuously generated in a specific position of the resin film corresponding to a specific position of the die along the extrusion direction of the resin film and is observable with the naked eye.
　このようなダイラインを発生させないことを目的としたＴダイが、従来、いくつか提案されている。
　例えば特許文献１には、溶融樹脂流路（流動性材料流路）の内壁面に硬質クロムめっき層を設けたＴダイが記載されている。
　また、例えば特許文献２には、炭化タングステンでコートされたＴダイが記載されている。
　さらに特許文献３には、リップの先端部分に樹脂くずが付着し、これが堆積すると、いわゆるメヤニとなり、これが樹脂膜へ付着して不良品を発生させてしまうことが記載されている。 Conventionally, several T dies aimed at preventing such a die line from being generated have been proposed.
For example, Patent Document 1 describes a T die in which a hard chromium plating layer is provided on the inner wall surface of a molten resin flow path (flowable material flow path).
For example, Patent Document 2 discloses a T die coated with tungsten carbide.
Further, Patent Document 3 describes that when resin waste adheres to the tip portion of the lip and accumulates, it becomes so-called “meani”, which adheres to the resin film and causes defective products.
　一方、「ポリブチレンテレフタレートの射出成形における金属表面が関与する表面炭化および充填不良」と題する非特許文献１には、プラスチックの射出成形を行ったときに生じる抹消部分での表面炭化現象等の不具合は、従来、剪断発熱、断熱圧縮による温度上昇と支燃性ガスによる燃焼が原因と考えられてきたものの、金型を含む成形機内の金属、高分子、および分解ガスの界面で解重合、水素引抜などが促進される触媒作用に伴い、支燃性ガスを伴わない条件でも発生し得ることが記載されている。 On the other hand, Non-Patent Document 1 entitled “Surface carbonization and filling failure involving metal surface in injection molding of polybutylene terephthalate” includes defects such as surface carbonization phenomenon at the erased portion that occurs when plastic injection molding is performed. In the past, it was thought to be caused by shear heating, temperature rise by adiabatic compression, and combustion by combustion-supporting gas, but depolymerization at the interface of metal, polymer, and cracked gas in the molding machine including the mold, hydrogen It is described that it can be generated even under conditions that do not involve a combustion-supporting gas due to the catalytic action that facilitates drawing and the like.
国際公開第２０１４／０３８４９０号パンフレットInternational Publication No. 2014/038490 Pamphlet 特許第４１１７５８９号公報Japanese Patent No. 4117589 特公平８－２９５５９号公報Japanese Examined Patent Publication No. 8-29559
　しかしながら、硬質クロムメッキは、母材との線膨張率の差により、微小亀裂（ヘアークラック）を生ずる場合がある。この場合、特許文献１に記載のＴダイのように、その溶融樹脂流路の内壁面に設けられた硬質クロムめっき層の微小亀裂に徐々に溶融樹脂が堆積する。また、表面の樹脂の一部が脱落した場合は、その脱落部分にも、同様に徐々に溶融樹脂が堆積する。そして、堆積した溶融樹脂が炭化または酸化を起こし、これがダイラインを発生させていた。 However, the hard chrome plating may cause micro cracks (hair cracks) due to the difference in coefficient of linear expansion from the base material. In this case, like the T-die described in Patent Document 1, the molten resin is gradually deposited on the microcracks of the hard chromium plating layer provided on the inner wall surface of the molten resin flow path. In addition, when a part of the resin on the surface falls off, the molten resin gradually accumulates in the same manner on the dropped part. Then, the deposited molten resin is carbonized or oxidized, which generates a die line.
　また、特許文献２に記載のＴダイの場合、必ずしも樹脂との付着性が低いとは言えず、付着した樹脂がダイラインを発生させていた。 In addition, in the case of the T die described in Patent Document 2, it cannot be said that the adhesiveness to the resin is necessarily low, and the adhered resin generates a die line.
　さらに、特許文献３に記載のように、溶融樹脂流路の内壁面が硬質クロムめっき層や炭化タングステン等の超鋼合金コートでない場合であっても、リップ部に１０ｎｍ以上の微細な凹凸を有していると、溶融樹脂が浸入し、付着し、大気に触れて酸化劣化することで、これがダイラインを発生させると考えられる。 Furthermore, as described in Patent Document 3, even when the inner wall surface of the molten resin flow path is not a hard chromium plating layer or a super steel alloy coat such as tungsten carbide, the lip portion has fine irregularities of 10 nm or more. In this case, it is considered that the molten resin enters, adheres, and is oxidized and deteriorated by contact with the atmosphere, thereby generating a die line.
　すなわち、従来、ダイラインを発生させないＴダイは提供されていなかった。 That is, conventionally, no T-die that does not generate a die line has been provided.
　本発明者は、上記のような課題を解決することを目的として鋭意検討を重ねた。そして、従来のステンレス鋼系のＴダイについて、それが有する溶融樹脂流路の内壁面および前記リップ部の表面にプラズマ窒化処理法等によって窒素原子を注入し、窒素原子をそのＴダイを構成している元素（例えば鉄やクロム等）と結合させて、その表面に窒素系金属間化合物からなる層を形成すると、その層は溶融樹脂の離型性に極めて優れ、硬度も高く、表面粗さも良好であるため、得られたＴダイを用いて樹脂フィルムを成形した場合、ダイラインが長期にわたって極めて形成され難いことを見出し、本発明を完成させた。 The present inventor has intensively studied for the purpose of solving the above problems. Then, with respect to a conventional stainless steel T-die, nitrogen atoms are injected into the inner wall surface of the molten resin flow channel and the surface of the lip portion by a plasma nitriding method or the like, and the nitrogen atoms constitute the T-die. When a layer composed of a nitrogen-based intermetallic compound is formed on the surface by combining with an element (for example, iron or chromium), the layer is extremely excellent in releasability of the molten resin, has high hardness, and has a surface roughness. Since it was good, when the resin film was formed using the obtained T-die, it was found that a die line was extremely difficult to be formed over a long period of time, and the present invention was completed.
　本発明は以下の（１）～（６）である。
（１）内部に溶融樹脂流路を有し、その吐出口にリップ部を有する、プラスチック成形用のステンレス鋼系Ｔダイの製造方法であって、
　未処理Ｔダイにプラズマ窒化処理を施して、前記溶融樹脂流路の内壁面および前記リップ部の表面に窒素系金属間化合物からなる層を形成する工程を備える、溶融樹脂の離型性に優れ、硬度が高いＴダイの製造方法。
（２）バイアス電圧を－１５０～－４００Ｖとし、前記未処理Ｔダイの温度を２５０～３５０℃として前記プラズマ窒化処理を行う、上記（１）に記載のＴダイの製造方法。
（３）熱可塑性樹脂からなるフィルムを得るためのＴダイが得られる、上記（１）または（２）に記載のＴダイの製造方法。
（４）Ｔダイの内部の溶融樹脂流路の内壁面およびリップ部の表面に対する溶融樹脂の離型性を向上させる方法であって、
　前記Ｔダイにプラズマ窒化処理を施して、前記溶融樹脂流路の内壁面および前記リップ部の表面に窒素系金属間化合物からなる層を形成する工程を備える、離型性向上方法。
（５）溶融樹脂流路の内壁面およびリップ部の表面に窒素系金属間化合物からなる層を有する、溶融樹脂の離型性に優れ、硬度が高い、プラスチック成形用のステンレス鋼系Ｔダイ。
（６）上記（１）～（３）のいずれかに記載のＴダイの製造方法によって製造された、上記（５）に記載のＴダイ。 The present invention includes the following (1) to (6).
(1) A method for producing a stainless steel T-die for plastic molding, having a molten resin flow path inside and a lip portion at the discharge port,
It has excellent mold releasability of molten resin, comprising a step of subjecting an untreated T die to plasma nitriding to form a layer made of a nitrogen-based intermetallic compound on the inner wall surface of the molten resin flow path and the surface of the lip portion. The manufacturing method of T-die with high hardness.
(2) The method for manufacturing a T die according to (1), wherein the plasma nitriding treatment is performed with a bias voltage of −150 to −400 V and a temperature of the untreated T die of 250 to 350 ° C.
(3) The method for producing a T die according to (1) or (2), wherein a T die for obtaining a film made of a thermoplastic resin is obtained.
(4) A method for improving the release property of the molten resin with respect to the inner wall surface of the molten resin flow path inside the T die and the surface of the lip portion,
A method for improving releasability, comprising: performing a plasma nitriding treatment on the T die to form a layer made of a nitrogen-based intermetallic compound on the inner wall surface of the molten resin flow path and the surface of the lip portion.
(5) A stainless steel T-die for plastic molding that has a layer made of a nitrogen-based intermetallic compound on the inner wall surface of the molten resin flow path and the surface of the lip portion, and has excellent mold release properties and high hardness.
(6) The T die according to (5) manufactured by the method of manufacturing a T die according to any one of (1) to (3) above.
　本発明によれば、溶融樹脂流路の内壁面およびリップ部の表面に対する溶融樹脂の離型性が極めて高く、硬度も高く、表面粗さも低位に保持されているため、それを用いて樹脂フィルムを成形した場合に、長期にわたってダイラインが極めて形成され難いＴダイおよびその製造方法を提供することができる。また、Ｔダイ内部の溶融樹脂流路の内壁面およびリップ部の表面に対する溶融樹脂の離型性を向上させる方法を提供することができる。 According to the present invention, since the releasability of the molten resin with respect to the inner wall surface of the molten resin flow path and the surface of the lip portion is extremely high, the hardness is high, and the surface roughness is maintained at a low level. Thus, it is possible to provide a T die in which a die line is extremely difficult to be formed over a long period of time and a method for manufacturing the same. Moreover, the method of improving the mold release property of the molten resin with respect to the inner wall surface of the molten resin flow path inside T-die and the surface of a lip | rip part can be provided.
好適例である本発明のＴダイの縦断面図（概略図）である。It is a longitudinal cross-sectional view (schematic diagram) of T-die of this invention which is a suitable example. 図１に示すＴダイのダイ本体の内壁面を示す側面図（概略図）である。It is a side view (schematic diagram) showing the inner wall surface of the die body of the T die shown in FIG. 固液間接触角測定装置の内部および測定例を表す写真である。It is a photograph showing the inside of a solid-liquid contact angle measuring device and a measurement example. プラズマ窒化処理したときの温度と、２９５℃におけるＣＯＰ樹脂の接触角の測定結果との関係を表すグラフである。It is a graph showing the relationship between the temperature at the time of plasma nitriding, and the measurement result of the contact angle of the COP resin at 295 ° C. 実施例にて得られた、プラズマ窒化処理時の温度と、表面粗さＲａ（μｍ）および硬度（ＨＶ Ｋｇｆ／ｍｍ2）との関係図である。FIG. 3 is a graph showing the relationship between the temperature during plasma nitriding, the surface roughness Ra (μm), and the hardness (HV Kgf / mm 2 ) obtained in an example. 実施例にて得られた、バイアス電圧値と、表面粗さＲａ（μｍ）および硬度（ＨＶ Ｋｇｆ／ｍｍ2）との関係図である。It is a relationship figure of bias voltage value, surface roughness Ra (micrometer), and hardness (HV Kgf / mm < 2 >) which were obtained in the Example. ブラズマ窒化処理の好ましい処理条件の範囲を示す図である。It is a figure which shows the range of the preferable process conditions of a plasma nitriding process.
　本発明について説明する。
　本発明は、内部に溶融樹脂流路を有し、その吐出口にリップ部を有する、プラスチック成形用のステンレス鋼系Ｔダイの製造方法であって、未処理Ｔダイにプラズマ窒化処理を施して、前記溶融樹脂流路の内壁面および前記リップ部の表面に窒素系金属間化合物からなる層を形成する工程を備える、溶融樹脂の離型性に優れ、硬度が高いＴダイの製造方法である。
　このような溶融樹脂の離型性に優れ、硬度が高いＴダイの製造方法を、以下では「本発明の製造方法」ともいう。 The present invention will be described.
The present invention relates to a method of manufacturing a stainless steel T die for plastic molding, which has a molten resin flow path inside and a lip portion at the discharge port, and plasma nitriding treatment is performed on an untreated T die. A method for producing a T-die having excellent molten resin releasability and high hardness, comprising a step of forming a layer made of a nitrogen-based intermetallic compound on the inner wall surface of the molten resin flow path and the surface of the lip portion. .
Such a method for producing a T-die having excellent mold releasability and high hardness is hereinafter also referred to as “the production method of the present invention”.
　また、本発明は、溶融樹脂流路の内壁面およびリップ部の表面に窒素系金属間化合物からなる層を有する、溶融樹脂の離型性に優れ、硬度が高い、プラスチック成形用のステンレス鋼系Ｔダイである。
　このような溶融樹脂の離型性に優れ、硬度が高い、プラスチック成形用のステンレス鋼系Ｔダイを、以下では「本発明のＴダイ」ともいう。 In addition, the present invention has a layer made of a nitrogen-based intermetallic compound on the inner wall surface of the molten resin flow path and the surface of the lip portion, and is excellent in the releasability of the molten resin and has high hardness, and is a stainless steel type for plastic molding T-die.
Such a stainless steel T-die for plastic molding that has excellent mold releasability and high hardness is hereinafter also referred to as “T-die of the present invention”.
　本発明のＴダイは、本発明の製造方法によって製造されたものであることが好ましい。 The T-die of the present invention is preferably manufactured by the manufacturing method of the present invention.
　本発明のＴダイについて、図１および図２にその好適態様を挙げて説明する。
　図１は、本発明のＴダイの好適態様の縦断面図であり、図２は、図１に示すＴダイのダイ本体の内壁面を示す側面図である。
　図１に示すように、本発明のＴダイ１（Ｔダイ１）は、一対のダイ部材３、４からなるダイ本体２を有している。そして、ダイ部材３、４の間に溶融樹脂流路５が形成されている。すなわち、ダイ部材３，４の内壁面が溶融樹脂流路５を構成している。溶融樹脂流路５は、上流側から順に、流入部６、マニホールド部７、およびスリット状の吐出部８を有している。吐出部８の吐出口の近傍の部分がリップ部９である。
　また、図２において、符号６ａ，７ａ，８ａは、流入部６、マニホールド部７、吐出部８のそれぞれにおけるダイ部材３（４）の壁面を示している。
　そして、溶融樹脂流路５を構成しているダイ部材３，４の内壁面と、リップ部９の表面とには、窒素系金属間化合物からなる層２０（窒素系金属間化合物層２０ともいう）が形成されている。 The T die of the present invention will be described with reference to preferred embodiments in FIGS.
FIG. 1 is a longitudinal sectional view of a preferred embodiment of the T die of the present invention, and FIG. 2 is a side view showing an inner wall surface of a die body of the T die shown in FIG.
As shown in FIG. 1, a T die 1 (T die 1) of the present invention has a die body 2 including a pair of die members 3 and 4. A molten resin flow path 5 is formed between the die members 3 and 4. That is, the inner wall surfaces of the die members 3 and 4 constitute the molten resin flow path 5. The molten resin flow path 5 has an inflow part 6, a manifold part 7, and a slit-like discharge part 8 in order from the upstream side. A portion near the discharge port of the discharge portion 8 is a lip portion 9.
In FIG. 2, reference numerals 6 a, 7 a, and 8 a indicate wall surfaces of the die member 3 (4) in each of the inflow portion 6, the manifold portion 7, and the discharge portion 8.
A layer 20 (also referred to as a nitrogen-based intermetallic compound layer 20) made of a nitrogen-based intermetallic compound is formed on the inner wall surfaces of the die members 3 and 4 constituting the molten resin flow path 5 and the surface of the lip portion 9. ) Is formed.
　このようなＴダイ１を用いてフィルムなどのプラスチックの成形品を成形する場合、初めに、Ｔダイ１の長手方向中央部にある流入部６は図示しない押出機に接続され、この流入部６から溶融樹脂流路５内に溶融樹脂が供給される。供給された溶融樹脂は、Ｔダイ１の長手方向に延びる略円形断面のマニホールド部７に流入し、Ｔダイ１の長手方向に広がった後に、スリット状の吐出部８に流入し、吐出部８の開口端縁（吐出口）から膜の形態で、図示しないローラー上に押し出される。 When a plastic molded product such as a film is formed using such a T-die 1, first, the inflow portion 6 at the center in the longitudinal direction of the T-die 1 is connected to an extruder (not shown). The molten resin is supplied into the molten resin flow path 5 from above. The supplied molten resin flows into the manifold portion 7 having a substantially circular cross section extending in the longitudinal direction of the T die 1, spreads in the longitudinal direction of the T die 1, and then flows into the slit-like ejection portion 8. From the opening edge (discharge port) of the film, it is extruded on a roller (not shown) in the form of a film.
　本発明のＴダイの形状はフィルム等のプラスチック成形に用いることができるものであれば特に限定されず、従来公知のものと同様の形状であってよい。 The shape of the T-die of the present invention is not particularly limited as long as it can be used for plastic molding of a film or the like, and may be the same shape as a conventionally known one.
　ここで、フィルム等の成型されるプラスチックの種類は特に限定されず、例えば、ポリメチルメタクリレート（ＰＭＭＡ）、ポリカーボネート（ＰＣ）、シクロオレフィン（ＣＯＰ）、ポリエチレンテレフタレート（ＰＥＴ）、ポリブチレンテレフタレート（ＰＢＴ）、ポリアリレート（ＰＡＲ）、ポリイミド（ＰＩ）、ポリスチレン（ＰＳ）、ポリプロピレン（ＰＰ）、ポリアミド（ＰＡ）、ポリエチレン（ＰＥ）、ポリアセタール（ＰＯＭ）、エチレン－酢酸ビニル共重合樹脂（ＥＶＡ）、アクリロニトリルブタジエンスチレン（ＡＢＳ）、ポリ塩化ビニル（ＰＶＣ）、ポリフェニレンオキサイド（ＰＰＯ）またはこれらの混合物などが挙げられる。 Here, the type of plastic to be molded such as a film is not particularly limited. For example, polymethyl methacrylate (PMMA), polycarbonate (PC), cycloolefin (COP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT). , Polyarylate (PAR), polyimide (PI), polystyrene (PS), polypropylene (PP), polyamide (PA), polyethylene (PE), polyacetal (POM), ethylene-vinyl acetate copolymer resin (EVA), acrylonitrile butadiene Examples thereof include styrene (ABS), polyvinyl chloride (PVC), polyphenylene oxide (PPO), or a mixture thereof.
　本発明のＴダイが備えるダイ本体の材質は、ステンレス鋼であれば特に限定されず、例えば従来公知のものと同様であってよい。 The material of the die body provided in the T-die of the present invention is not particularly limited as long as it is stainless steel, and may be the same as that conventionally known, for example.
　本発明のＴダイが有する窒素系金属間化合物層は、ダイ本体を構成する元素（例えば鉄やクロム）と窒素とが結合してなる窒素系金属間化合物からなり、これが層状をなしているものである。窒素系金属間化合物としては、例えばＣｒxＮやＦｅyＮが挙げられる。
　窒素系金属間化合物層は、従来公知のステンレス鋼系Ｔダイにおける溶融樹脂流路の内壁面およびリップ部の表面に窒素原子を注入して形成するので、めっきのように表面を被覆する場合とは異なり、被膜（窒素系金属間化合物層）と母材（ダイ本体）とを区別する厳密な境界が存在するわけではない。ただし、従来公知の方法を用いて断面を観察すると、表面に窒素系金属間化合物からなる層が形成されていることを確認することができる。その層の中側が拡散層であり、さらにその中側は窒素が浸入していない母材である。 The nitrogen-based intermetallic compound layer of the T die of the present invention is composed of a nitrogen-based intermetallic compound formed by combining elements (for example, iron and chromium) constituting the die body and nitrogen, and this is a layered structure. It is. Examples of the nitrogen-based intermetallic compound include Cr x N and Fe y N.
The nitrogen-based intermetallic compound layer is formed by injecting nitrogen atoms into the inner wall surface of the molten resin flow path and the surface of the lip portion in a conventionally known stainless steel T-die, so that the surface is coated as in plating In contrast, there is no strict boundary between the coating (nitrogen-based intermetallic compound layer) and the base material (die body). However, when a cross section is observed using a conventionally known method, it can be confirmed that a layer made of a nitrogen-based intermetallic compound is formed on the surface. The inner side of the layer is a diffusion layer, and the inner side is a base material into which nitrogen does not enter.
　上記の通りであるから、窒素系金属間化合物層の厚さを厳密に規定することは困難であるが、概ね１０～５０μｍであることが好ましく、１０～１００μｍであることがより好ましい。 As described above, it is difficult to strictly define the thickness of the nitrogen-based intermetallic compound layer, but it is preferably approximately 10 to 50 μm, and more preferably 10 to 100 μm.
　上記のように、本発明のＴダイは、従来公知のステンレス鋼系Ｔダイにおける溶融樹脂流路の内壁面およびリップ部の表面に窒素原子を注入して形成するが、この窒素原子の注入は、プラズマ窒化処理によることが好ましい。すなわち、本発明のＴダイは、本発明の製造方法によって製造することが好ましい。 As described above, the T die of the present invention is formed by injecting nitrogen atoms into the inner wall surface of the molten resin flow path and the surface of the lip portion in a conventionally known stainless steel type T die. It is preferable to use plasma nitriding treatment. That is, the T die of the present invention is preferably manufactured by the manufacturing method of the present invention.
　プラズマ窒化処理は従来公知のものであってよい。例えば、窒素ガスを注入しながらタングステンフィラメントに電流を流すと窒素ガスがプラズマ状態となり、プラズマ窒化処理を行う対象物（未処理Ｔダイ）にマイナスバイアスをかけると、窒素プラズマ（Ｎ+）が対象物（未処理Ｔダイ）の表面に衝突し注入されてＦｅ4ＮやＣｒ4Ｎ等が生成される。 The plasma nitriding treatment may be a conventionally known one. For example, when a current is passed through a tungsten filament while injecting nitrogen gas, the nitrogen gas becomes a plasma state. When a negative bias is applied to an object to be plasma-nitrided (untreated T-die), nitrogen plasma (N + ) is targeted. It collides with the surface of the object (untreated T die) and is injected to produce Fe 4 N, Cr 4 N, or the like.
　プラズマイオン注入加工において、フィラメント電流は１００～２００Ａ、ディスチャージ電流は１００～３００Ａ、プラズマ窒化処理を行う対象物（未処理Ｔダイ）に対するバイアス電圧は０．１～１０００Ｖ、窒素圧力は０．５～５Ｐａ、処理時間は１０～１０００分とすることが好ましい。 In plasma ion implantation processing, the filament current is 100 to 200 A, the discharge current is 100 to 300 A, the bias voltage for the object to be plasma-nitrided (untreated T-die) is 0.1 to 1000 V, and the nitrogen pressure is 0.5 to 5 Pa and the treatment time are preferably 10 to 1000 minutes.
　また、バイアス電圧は－１５０～－４００Ｖであることが好ましい。表面硬さが高まるからである。 The bias voltage is preferably −150 to −400V. This is because the surface hardness is increased.
　プラズマ窒化処理時の処理対象物（未処理Ｔダイ）の温度を２５０～３５０℃とすることが好ましい。
　処理対象物（未処理Ｔダイ）の温度は、バイアス電圧の大きさ（負のバイアス電圧の絶対値）を大きくすると、高くなる傾向がある。また、バイアス電圧を付加しつづける時間を長くしても、同様に、処理対象物（未処理Ｔダイ）の温度が高くなる傾向がある。したがって、処理対象物（未処理Ｔダイ）のバイアス電圧の大きさや、バイアス電圧を付加する時間を調整することによって、処理対象物（未処理Ｔダイ）の温度を所望の温度に調整することができる。 The temperature of the object to be treated (untreated T die) during the plasma nitriding treatment is preferably set to 250 to 350 ° C.
The temperature of the object to be processed (unprocessed T die) tends to increase as the magnitude of the bias voltage (absolute value of the negative bias voltage) is increased. Further, even if the time for which the bias voltage is continuously applied is lengthened, the temperature of the processing object (unprocessed T die) tends to increase similarly. Therefore, the temperature of the processing object (unprocessed T die) can be adjusted to a desired temperature by adjusting the magnitude of the bias voltage of the processing object (unprocessed T die) and the time for applying the bias voltage. it can.
　プラズマ窒化処理は、従来公知の装置を用いて行うことができる。
　例えば、真空チャンバー内に、窒素プラズマによってプラズマイオン注入加工を施すプラズマイオン注入ガンが設置され、それに対向する位置に未処理Ｔダイ（従来公知のステンレス鋼系Ｔダイであってよい）を配置できるように構成されている装置を用いることができる。 The plasma nitriding treatment can be performed using a conventionally known apparatus.
For example, a plasma ion implantation gun for performing plasma ion implantation processing by nitrogen plasma is installed in a vacuum chamber, and an untreated T die (which may be a conventionally known stainless steel T die) can be disposed at a position facing it. An apparatus configured as described above can be used.
　本発明の離型性向上方法について説明する。
　本発明の離型性向上方法は、Ｔダイの内部の溶融樹脂流路の内壁面およびリップ部の表面に対する溶融樹脂の離型性を向上させる方法であって、未処理Ｔダイに前記溶融樹脂流路の内壁面および前記リップ部の表面にプラズマ窒化処理を施して窒素系金属間化合物からなる層を形成する工程を備える方法である。 The method for improving releasability of the present invention will be described.
The method for improving the releasability of the present invention is a method for improving the releasability of the molten resin with respect to the inner wall surface of the molten resin flow path inside the T die and the surface of the lip part. The method includes a step of plasma nitriding the inner wall surface of the flow path and the surface of the lip portion to form a layer made of a nitrogen-based intermetallic compound.
　本発明の離型性向上方法は、従来公知のプラスチック成形用のステンレス鋼系Ｔダイ（すなわち未処理Ｔダイ）にプラズマ窒化処理を施して、その溶融樹脂流路の内壁面およびリップ部の表面に窒素系金属間化合物からなる層を形成する工程を備える方法である。これによって、Ｔダイ内部の溶融樹脂流路の内壁面およびリップ部の表面に対する溶融樹脂の離型性を向上させることができる。
　プラズマ窒化処理の方法は、前述の本発明の製造方法におけるプラズマ窒化処理と同様であってよい。 According to the method for improving releasability of the present invention, a conventionally known stainless steel T die for plastic molding (that is, an untreated T die) is subjected to plasma nitriding treatment, and the inner wall surface of the molten resin channel and the surface of the lip portion And a step of forming a layer made of a nitrogen-based intermetallic compound. Thereby, the releasability of the molten resin with respect to the inner wall surface of the molten resin flow path inside the T die and the surface of the lip portion can be improved.
The plasma nitriding method may be the same as the plasma nitriding treatment in the manufacturing method of the present invention described above.
＜実施例１＞
　Ｔダイを製造するときに用い得る鋼種の鋼片を用意し、これらに各種条件でプラズマ窒化処理して試験片を得た。そして、試験片について、硬度測定試験、表面粗さ測定試験およびシクロオレフィンポリマー（ＣＯＰ）樹脂を用いた離型性試験を行った。以下に具体的に記す。 <Example 1>
Steel pieces of steel types that can be used when manufacturing the T-die were prepared, and these were subjected to plasma nitriding treatment under various conditions to obtain test pieces. The test piece was subjected to a hardness measurement test, a surface roughness measurement test, and a releasability test using a cycloolefin polymer (COP) resin. This is specifically described below.
　鋼片は以下の第１表に示す組成を備えるプラスチック金型用鋼（ＵＤＤＥＨＯＬＭ社製、商品名：スタバックス）である。鋼片の大きさは１０ｍｍ×１０ｍｍ×厚さ２ｍｍであり、熱処理後、使用面表面を、砥粒を用いて研磨加工し、Ｒａが０．００５μｍ（ＩＳＯ４２８７）となるように仕上げたものである。 The steel slab is a steel for plastic molds having the composition shown in Table 1 below (made by UDDEHOLM, trade name: Stabux). The size of the steel piece is 10 mm × 10 mm × thickness 2 mm. After heat treatment, the surface of the surface used is polished with abrasive grains and finished so that Ra is 0.005 μm (ISO 4287). .
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　上記の鋼片について、後に示す第２表に示す各種条件のプラズマ窒化処理を施して、試験片を得た。プラズマ窒化処理は、新明和工業株式会社製、商品名：ＰＩＮＫを使用した。 The above steel pieces were subjected to plasma nitriding treatment under various conditions shown in Table 2 below to obtain test pieces. For plasma nitriding treatment, trade name: PINK manufactured by Shin Meiwa Kogyo Co., Ltd. was used.
　硬度測定試験はマイクロビッカース硬さ試験（押込荷重１０ｇｆ）に基づいて行った。 The hardness measurement test was performed based on the micro Vickers hardness test (indentation load 10 gf).
　表面粗さ測定試験はＪＩＳ Ｂ ０６０１に基づき、算術平均粗さ（Ｒａ）を求めて評価した。 The surface roughness measurement test was performed by calculating the arithmetic average roughness (Ra) based on JIS B 0601.
　離型性試験について説明する。
　ペレット状のシクロオレフィンポリマー樹脂（ＣＯＰ樹脂）（日本ゼオン株式会社製、商品名ＺＥＯＮＯＲ（登録商標）、１４２０Ｒ（ゼオノア））を用意し、ＣＯＰ樹脂の各試験片に対する、２９５℃における接触角を測定した。以下に測定手順を具体的に示す。
　なお、２９５℃は、Ｔダイを用いてＣＯＰ樹脂からフィルムの成形品を製造するときのＴダイおよびＣＯＰ樹脂の温度とほぼ同一温度である。したがって、以下に具体的に示す測定手順によって測定される接触角が大きい場合は、実際にＴダイを用いてＣＯＰ樹脂を溶融してフィルムの成形品を製造するときに、ＣＯＰ樹脂はＴダイの表面に対して離型性が高いと判断できる。後述するように、実際のＴダイの使用雰囲気は大気であるのに対して窒素雰囲気内で接触角を測定する。これは、金属表面が有する基本的な樹脂との離型性を、酸化や炭化の影響を除いた上で評価するためである。実際は大気中にさらされるが、炭化、酸化の影響が入り込んで、金属表面自体の特性が把握できない。また、酸化の影響は、Ｔダイリップを窒素雰囲気とすることで、ある程度は回避することも可能である。 The releasability test will be described.
Prepare pellet-shaped cycloolefin polymer resin (COP resin) (manufactured by ZEON Corporation, trade name ZEONOR (registered trademark), 1420R (Zeonor)), and measure the contact angle at 295 ° C. for each test piece of COP resin. did. The measurement procedure is specifically shown below.
In addition, 295 degreeC is the substantially same temperature as the temperature of T die and COP resin when manufacturing the molded article of a film from COP resin using T die. Therefore, when the contact angle measured by the measurement procedure specifically shown below is large, when the COP resin is actually melted using a T die to produce a molded product of the COP resin, It can be judged that the releasability is high with respect to the surface. As will be described later, the actual use atmosphere of the T-die is air, whereas the contact angle is measured in a nitrogen atmosphere. This is to evaluate the releasability from the basic resin on the metal surface after removing the influence of oxidation and carbonization. Although it is actually exposed to the atmosphere, the effects of carbonization and oxidation enter, and the characteristics of the metal surface itself cannot be grasped. Moreover, the influence of oxidation can be avoided to some extent by making the T die lip a nitrogen atmosphere.
　接触角の測定手順は、以下の通りである。
［１］ＣＯＰ樹脂ペレットを予め８０℃で４時間以上乾燥した。
［２］試験片を赤外線加熱炉内に装填し、その表面にＣＯＰ樹脂ペレットを設置し、窒素雰囲気内で２５℃（常温）から３分間で、２９５℃まで昇温した。
［３］２９５℃に到達の後、この温度を保持し、１分間経過時点で接触角を測定した。接触角の測定には、恒温濡れ性試験機である固液間接触角測定装置（ＷＥＴ－１２００、アルバック理工製）を使用した。そして、この測定結果に基づき、ＪＩＳ Ｒ ３２５７「基板ガラス表面のぬれ性試験方法」に従って接触角を算出した。 The contact angle measurement procedure is as follows.
[1] COP resin pellets were previously dried at 80 ° C. for 4 hours or more.
[2] The test piece was loaded into an infrared heating furnace, COP resin pellets were placed on the surface thereof, and the temperature was raised from 25 ° C. (normal temperature) to 295 ° C. in 3 minutes in a nitrogen atmosphere.
[3] After reaching 295 ° C., this temperature was maintained, and the contact angle was measured after 1 minute. For the measurement of the contact angle, a solid-liquid contact angle measuring device (WET-1200, manufactured by ULVAC-RIKO), which is a constant temperature wettability tester, was used. Based on this measurement result, the contact angle was calculated according to JIS R 3257 “Testing method for wettability of substrate glass surface”.
　上記のような方法で、各種条件でプラズマ窒化処理して得た試験片について、硬度測定試験、表面粗さ測定試験および接触角測定を行った。なお、比較のため、プラズマ窒化処理を施していない鋼片についても、同様の試験を行った。図３に、上記の固液間接触角測定装置の内部が２９５℃に到達したときのＣＯＰ樹脂ペレットの様子を示す写真を示す。
　結果を第２表および図４に示す。
　図４は横軸（Ｘ軸）を温度（℃）（プラズマ窒化処理したときの温度）、縦軸（Ｙ軸）を接触角（２９５℃におけるＣＯＰ樹脂の接触角の測定結果）とするグラフである。
　なお、図４は、各測定値にバイアス電圧を記載し、温度のみでは接触角が説明できない事実を記載したものである。 The test piece obtained by plasma nitriding treatment under various conditions by the above method was subjected to a hardness measurement test, a surface roughness measurement test, and a contact angle measurement. For comparison, a similar test was performed on a steel piece that was not plasma-nitrided. In FIG. 3, the photograph which shows the mode of a COP resin pellet when the inside of said solid-liquid contact angle measuring apparatus reaches | attains 295 degreeC is shown.
The results are shown in Table 2 and FIG.
FIG. 4 is a graph in which the horizontal axis (X-axis) is temperature (° C.) (temperature when plasma nitriding is performed), and the vertical axis (Y-axis) is the contact angle (measurement result of COP resin contact angle at 295 ° C.). is there.
FIG. 4 shows the fact that the bias voltage is described in each measured value, and the contact angle cannot be explained only by the temperature.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　また、第２表に示すデータの中の、バイアス電圧値が３００Ｖであってプラズマ窒化処理時の温度が２４０～３２０℃であるもの、および、バイアス電圧値が３５０Ｖであってプラズマ窒化処理時の温度が３５０℃であるものについて、プラズマ窒化処理時の温度と、表面粗さＲａ（μｍ）および硬度（ＨＶ Ｋｇｆ／ｍｍ2）との関係をグラフにした。図５に示す。 Of the data shown in Table 2, the bias voltage value is 300 V and the temperature during plasma nitriding is 240 to 320 ° C., and the bias voltage value is 350 V and the plasma nitriding time is For a sample having a temperature of 350 ° C., the relationship between the temperature during plasma nitriding, the surface roughness Ra (μm) and the hardness (HV Kgf / mm 2 ) was graphed. As shown in FIG.
　また、表２に示すデータの中の、プラズマ窒化処理時の温度が３００℃であるものについて、バイアス電圧値と、表面粗さＲａ（μｍ）および硬度（ＨＶ Ｋｇｆ／ｍｍ2）との関係をグラフにした。図６に示す。 Further, in the data shown in Table 2, the relationship between the bias voltage value, the surface roughness Ra (μm) and the hardness (HV Kgf / mm 2 ) for the plasma nitriding temperature of 300 ° C. Made a graph. As shown in FIG.
　第２表および図４～図６に示す測定結果から、プラズマ窒化処理を施した試験片は、接触角が３９°程度から５４°超を示し、未処理の鋼片の３５°と比較した場合に高く、高い接触角を備えることが確認できた。
　また、未処理の鋼片の硬度がＨＶ５５０であったのに対して、プラズマ窒化処理を施した試験片については、最大でＨＶ１３００まで硬度が上昇した。このような硬度の上昇は、プラズマ窒化処理によって窒素原子が鋼内に侵入し、Ｃｒ4Ｎ、Ｆｅ4Ｎ系の金属間化合物を生じるためと考えられる。
　なお、試験片の表面粗さは未処理の鋼片の表面粗さの場合（Ｒａ：０．００５）と比べて粗くなったが、Ｔダイの実用上は使用可能なレベルと判断する。 From the measurement results shown in Table 2 and FIGS. 4 to 6, the test piece subjected to the plasma nitriding treatment showed a contact angle of about 39 ° to more than 54 °, compared with 35 ° of the untreated steel piece. It was confirmed that it had a high contact angle.
In addition, the hardness of the untreated steel slab was HV550, whereas the hardness of the test specimen subjected to the plasma nitriding treatment increased to HV1300 at the maximum. Such an increase in hardness is thought to be because nitrogen atoms enter the steel by the plasma nitriding treatment to produce Cr 4 N, Fe 4 N intermetallic compounds.
In addition, although the surface roughness of the test piece became rough compared with the case of the surface roughness of the untreated steel piece (Ra: 0.005), it is determined that the T die can be used practically.
＜実施例２＞
　処理温度が最高値３５０℃の試験片♯３では、観察終了後約１ヶ月の大気保存で若干の着色（酸化と考える）が発生した。これはプラズマ窒化処理によって鋼材のもつ耐腐食性が若干失われたためと推測される。耐腐食性が大幅に損なわれた場合、商品価値を損ねる。
　この着色を懸念して１年間の大気保存を想定し、アレニウスの式に基づき加速試験を実施した。その結果、３２０℃以下のプラズマ窒化処理温度を施した試験片の場合は、この着色現象は見られなかった。 <Example 2>
In test piece # 3 having a maximum treatment temperature of 350 ° C., slight coloring (considered as oxidation) occurred after storage in the atmosphere for about one month after the end of observation. This is presumably because the corrosion resistance of the steel material was slightly lost by the plasma nitriding treatment. If the corrosion resistance is significantly impaired, the commercial value is impaired.
In consideration of this coloring, an accelerated test was carried out based on the Arrhenius equation, assuming 1-year atmospheric preservation. As a result, in the case of a test piece subjected to a plasma nitriding temperature of 320 ° C. or less, this coloring phenomenon was not observed.
　実施例１、２の結果から、プラズマ窒化処理には、図７に示すような、好ましい範囲（限界領域）が存在することが発見された。
　プラズマ窒化処理の温度が２８０℃以下では硬度が低く、逆に３２０℃以上では耐腐食性が弱くなる。また、バイアス電圧が－４００Ｖ未満ではスパッタにより表面が粗くなり、－１５０Ｖ超では表面粗さへの影響は小さくなるが、硬度が低くなる。効果的な窒化の処理領域は処理温度２８０℃以上３２０℃以下、バイアス電圧－１５０Ｖ～－４００Ｖであり、この領域では耐腐食性が損なわれず、硬度も高い。 From the results of Examples 1 and 2, it was found that there is a preferable range (limit region) as shown in FIG.
When the temperature of the plasma nitriding treatment is 280 ° C. or lower, the hardness is low, and conversely, when the temperature is 320 ° C. or higher, the corrosion resistance is weak. If the bias voltage is less than −400 V, the surface becomes rough due to sputtering, and if it exceeds −150 V, the influence on the surface roughness is reduced, but the hardness is lowered. An effective nitriding treatment region has a treatment temperature of 280 ° C. or more and 320 ° C. or less and a bias voltage of −150 V to −400 V. In this region, the corrosion resistance is not impaired and the hardness is high.
　本発明のＴダイを用いて、溶融樹脂をＴダイから吐出しながら型に塗布する溶融微細転写（登録商標）法を行うと、本発明のＴダイでは溶融樹脂とＴダイのリップ部との剥離性が向上しているので、平滑な塗布表面性状が実現され、低温の金型に樹脂を高速で塗布できるようになると考える。 When the molten fine transfer (registered trademark) method in which the molten resin is applied to the mold while discharging the molten resin from the T die is performed using the T die of the present invention, the molten resin and the lip portion of the T die are used in the T die of the present invention. Since the releasability is improved, it is considered that a smooth coating surface property is realized, and the resin can be applied to a low temperature mold at a high speed.
　１　Ｔダイ
　２　ダイ本体
　３、４　ダイ部材
　５　溶融樹脂流路
　８　吐出部
　９　リップ部
　２０　めっき層 DESCRIPTION OF SYMBOLS 1 T die 2 Die body 3, 4 Die member 5 Molten resin flow path 8 Discharge part 9 Lip part 20 Plating layer

Claims (6)

  1. 　内部に溶融樹脂流路を有し、その吐出口にリップ部を有する、プラスチック成形用のステンレス鋼系Ｔダイの製造方法であって、
    　未処理Ｔダイにプラズマ窒化処理を施して、前記溶融樹脂流路の内壁面および前記リップ部の表面に窒素系金属間化合物からなる層を形成する工程を備える、溶融樹脂の離型性に優れ、硬度が高いＴダイの製造方法。     A method of manufacturing a stainless steel T-die for plastic molding, having a molten resin flow path inside and a lip portion at its discharge port,
    It has excellent mold releasability of molten resin, comprising a step of subjecting an untreated T die to plasma nitriding to form a layer made of a nitrogen-based intermetallic compound on the inner wall surface of the molten resin flow path and the surface of the lip portion. The manufacturing method of T-die with high hardness.
  2. 　バイアス電圧を－１５０～－４００Ｖとし、前記未処理Ｔダイの温度を２５０～３５０℃として前記プラズマ窒化処理を行う、請求項１に記載のＴダイの製造方法。 2. The method of manufacturing a T die according to claim 1, wherein the plasma nitriding treatment is performed with a bias voltage of −150 to −400 V and a temperature of the unprocessed T die of 250 to 350 ° C.
  3. 　熱可塑性樹脂からなるフィルムを得るためのＴダイが得られる、請求項１または２に記載のＴダイの製造方法。 The method for producing a T-die according to claim 1 or 2, wherein a T-die for obtaining a film made of a thermoplastic resin is obtained.
  4. 　Ｔダイの内部の溶融樹脂流路の内壁面およびリップ部の表面に対する溶融樹脂の離型性を向上させる方法であって、
    　前記Ｔダイにプラズマ窒化処理を施して、前記溶融樹脂流路の内壁面および前記リップ部の表面に窒素系金属間化合物からなる層を形成する工程を備える、離型性向上方法。     A method for improving the releasability of the molten resin with respect to the inner wall surface of the molten resin flow path inside the T-die and the surface of the lip part,
    A method for improving releasability, comprising: performing a plasma nitriding treatment on the T die to form a layer made of a nitrogen-based intermetallic compound on the inner wall surface of the molten resin flow path and the surface of the lip portion.
  5. 　溶融樹脂流路の内壁面およびリップ部の表面に窒素系金属間化合物からなる層を有する、溶融樹脂の離型性に優れ、硬度が高い、プラスチック成形用のステンレス鋼系Ｔダイ。 A stainless steel T die for plastic molding that has a layer made of a nitrogen-based intermetallic compound on the inner wall surface of the molten resin flow path and the surface of the lip portion, and has excellent mold release properties and high hardness.
  6. 　請求項１～３のいずれかに記載のＴダイの製造方法によって製造された、請求項５に記載のＴダイ。 The T-die according to claim 5, which is manufactured by the method for manufacturing a T-die according to any one of claims 1 to 3.
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