JPH0561085B2 - - Google Patents
Info
- Publication number
- JPH0561085B2 JPH0561085B2 JP57213063A JP21306382A JPH0561085B2 JP H0561085 B2 JPH0561085 B2 JP H0561085B2 JP 57213063 A JP57213063 A JP 57213063A JP 21306382 A JP21306382 A JP 21306382A JP H0561085 B2 JPH0561085 B2 JP H0561085B2
- Authority
- JP
- Japan
- Prior art keywords
- mold
- molded product
- resin
- press
- thermal conductivity
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 229920005989 resin Polymers 0.000 claims description 27
- 239000011347 resin Substances 0.000 claims description 27
- 238000000465 moulding Methods 0.000 claims description 11
- 239000004020 conductor Substances 0.000 claims description 9
- -1 polypropylene Polymers 0.000 claims description 9
- 239000004743 Polypropylene Substances 0.000 claims description 7
- 229920001155 polypropylene Polymers 0.000 claims description 7
- 238000000034 method Methods 0.000 claims description 6
- 229920005992 thermoplastic resin Polymers 0.000 claims description 3
- 238000001816 cooling Methods 0.000 claims description 2
- 239000000463 material Substances 0.000 claims 1
- 230000002950 deficient Effects 0.000 description 5
- 229920002799 BoPET Polymers 0.000 description 4
- 239000005041 Mylar™ Substances 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 4
- 239000000919 ceramic Substances 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 230000037303 wrinkles Effects 0.000 description 3
- 229920006361 Polyflon Polymers 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000001746 injection moulding Methods 0.000 description 2
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229920000139 polyethylene terephthalate Polymers 0.000 description 1
- 239000005020 polyethylene terephthalate Substances 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- BFKJFAAPBSQJPD-UHFFFAOYSA-N tetrafluoroethene Chemical group FC(F)=C(F)F BFKJFAAPBSQJPD-UHFFFAOYSA-N 0.000 description 1
- 239000002470 thermal conductor Substances 0.000 description 1
Classifications
-
- 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
- B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
- B29C43/32—Component parts, details or accessories; Auxiliary operations
- B29C43/52—Heating or cooling
-
- 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
- B29C33/00—Moulds or cores; Details thereof or accessories therefor
- B29C33/56—Coatings, e.g. enameled or galvanised; Releasing, lubricating or separating agents
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
- Casting Or Compression Moulding Of Plastics Or The Like (AREA)
Description
【発明の詳細な説明】
本発明は熱可塑性樹脂のプレス成形に関するも
のである。熱可塑性樹脂（以下樹脂という）を押
出機などで可塑化溶融し、これを金型間でプレス
冷却して得られる成形品は射出成形品と較べると
次のような利点がある。射出成形では閉じられた
金型空間にゲートより溶融樹脂を圧入するため樹
脂の配向が生じ、成形品に残留歪が残るので、成
形品にねじれ、ゆがみなどの変形が生じやすいこ
とまたゲート近傍では残留歪が強く残るので、物
性的な弱点となる。これに対しプレス成形では、
金型間に供給された溶融樹脂を型締めによる圧力
により、金型面を一様に流動させて賦形するの
で、残留歪が殆んどなく、成形品の変形がない、
またゲートもないため射出成形品は射出成形品に
較べ、ウエルド部をなくするか、少なくすること
ができる。即ち、プレス成形法は射出成形法に較
べ、ゲート部、ウエルド部等の物性的に弱い部分
がないばかりでなく、変形のない良好な成形品を
得ることができる。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to press molding of thermoplastic resin. A molded product obtained by plasticizing and melting a thermoplastic resin (hereinafter referred to as resin) using an extruder or the like and press-cooling it between molds has the following advantages when compared to an injection molded product. In injection molding, molten resin is press-fitted into a closed mold space through a gate, which causes the resin to become oriented and leave residual strain in the molded product. Since strong residual strain remains, this becomes a physical weakness. On the other hand, in press forming,
Since the molten resin supplied between the molds is shaped by uniformly flowing over the mold surface under the pressure of mold clamping, there is almost no residual strain and no deformation of the molded product.
Also, since there is no gate, injection molded products can eliminate or reduce welds compared to injection molded products. That is, compared to injection molding, press molding not only does not have physically weak parts such as gate parts and weld parts, but also can produce good molded products without deformation.
しかしながら、この方法で成形する場合、供給
された溶融樹脂が加圧されるまえから金型に接し
た部分は他の部分に較べ、著しく光沢が悪くなつ
たり、小さなシワが発生するなど、外観上良好な
成形品を得ることが出来ない。 However, when molding is performed using this method, the parts that come into contact with the mold before the supplied molten resin is pressurized may have a significantly lower gloss than other parts, or small wrinkles may appear. It is not possible to obtain a good molded product.
上記のトラブル（以下にこのトラブルをコール
ドマークと呼ぶ）が生じるのは溶融樹脂が金型上
に供給されてから、プレス圧力により溶融樹脂が
金型キヤビテイを流れるまでの間に金型に接して
いる部分は金型面より熱を吸収されて、樹脂温度
が低下するためである。 The above trouble (hereinafter referred to as cold mark) occurs when the molten resin comes into contact with the mold after it is supplied onto the mold and before it flows through the mold cavity due to press pressure. This is because heat is absorbed from the mold surface and the temperature of the resin decreases.
本発明者らは鋭意検討の結果、溶融状態にある
ポリプロピレン樹脂を金型上に供給し、加圧冷却
して成形品を得るに際し、供給された溶融樹脂が
加圧される前から接する金型の部分を含む面を熱
伝導率が６×10-3cal/cm・sec・℃以下の熱不良導
体層で覆つておくことにより、前記トラブルは解
消されることを見出した。 As a result of extensive studies, the present inventors found that when polypropylene resin in a molten state is supplied onto a mold and cooled under pressure to obtain a molded product, the supplied molten resin comes into contact with the mold before being pressurized. It has been found that the above-mentioned trouble can be solved by covering the surface including the part with a thermally poor conductor layer having a thermal conductivity of 6×10 -3 cal/cm·sec·°C or less.
使用する熱不良導体としては熱伝導率が６×
10-3cal/cm・sec・℃、以下のものを用いることが
重要で、この値がより大きければ、実用上の効果
はない。 The thermal conductivity of the thermally poor conductor used is 6×
It is important to use a value below 10 -3 cal/cm・sec・℃; if this value is larger, there will be no practical effect.
本発明に用いる熱不良導体として好適なもの
に、樹脂、セラミツクをあげることが出来る。樹
脂フイルムを金型面に貼着しておいてもよいが、
このようにすると成形品から該フイルムを剥取ら
なければならないので手数がかかり好ましくな
い。繰返し、多数回の成形時の熱と圧力に耐え、
金型を十分に密着する耐久性のよい皮膜で金型面
をコートしておくことが望ましい。上記の耐久性
のよい樹脂コート剤としてはポリ四弗化エチレン
など弗素系の樹脂があり、これらは熱伝導率(ca
ｌ／cm・ｓｅｃ・℃）が10-4オーダで、効果が最も大き
い。
更に耐熱性のよいコート剤としてはセラミツクが
あり、300℃以上の高温にも十分に耐えるが、熱
伝導率の点では上記樹脂よりもやや大きく10-3オ
ーダであるから、コールドマーク防止効果の点で
は上記樹脂より劣るので、樹脂と同じ効果を得よ
うとすれば、厚めにコートする必要がある。これ
ら熱不良導体のコート厚みとしては200〜500μが
適当である。 Resins and ceramics can be cited as suitable thermal conductors for use in the present invention. A resin film may be pasted on the mold surface, but
If this is done, the film must be peeled off from the molded product, which is time-consuming and undesirable. Withstands the heat and pressure of repeated molding,
It is desirable to coat the mold surface with a durable film that sufficiently adheres to the mold. The durable resin coating agents mentioned above include fluorine-based resins such as polytetrafluoroethylene, which have a high thermal conductivity (ca
l/cm・sec・℃) is on the order of 10 -4 , which is the largest effect.
Furthermore, ceramic is a coating agent with good heat resistance, and it can withstand high temperatures of over 300℃, but its thermal conductivity is slightly higher than that of the resins mentioned above, on the order of 10 -3 , so it is not effective in preventing cold marks. In this respect, it is inferior to the above-mentioned resins, so if you want to obtain the same effect as the resins, it is necessary to coat it thicker. The appropriate coating thickness for these thermally poor conductors is 200 to 500 μm.
コールドマークが防止でき、成形サイクルを低
下させない熱不良導体層の厚みは、用いる熱不良
導体の熱伝導率、成形に使用する樹脂、その温
度、金型温度、及び金型上に溶融樹脂が供給され
てから、溶融樹脂にプレス圧力が作用して金型内
を流れるまでの時間等によつて変つてくるので、
これらの条件と成形サイクル等を考慮して熱不良
等体層の厚みを決めるのがよい。以下に実施例に
より詳細に説明する。 The thickness of the thermally defective conductor layer that prevents cold marks and does not reduce the molding cycle depends on the thermal conductivity of the thermally defective conductor used, the resin used for molding, its temperature, the mold temperature, and the supply of molten resin onto the mold. It varies depending on the time it takes for the molten resin to flow through the mold after press pressure is applied to it.
It is preferable to decide the thickness of the thermally defective layer in consideration of these conditions and the molding cycle. Examples will be described in detail below.
実施例 １
本発明の実施要領を図面によつて示す。第１図
はプラテンに取付けたプレス成形金型部の略断面
図である。第２図は本発明方法により得られる成
形品の斜視図である。第１図において１はプレス
機の上プラテンで、油圧により降下、上昇するよ
うになつている。２はプレス機の下プラテン、
３，４は各々プラテンに取付けられた上金型、下
金型、５は熱不良導体層、６はこの上に供給され
た溶融樹脂である。Example 1 The implementation procedure of the present invention will be illustrated by the drawings. FIG. 1 is a schematic cross-sectional view of a press molding die attached to a platen. FIG. 2 is a perspective view of a molded article obtained by the method of the present invention. In FIG. 1, reference numeral 1 denotes the upper platen of the press, which is lowered and raised by hydraulic pressure. 2 is the lower platen of the press,
Reference numerals 3 and 4 designate an upper mold and a lower mold respectively attached to a platen, 5 a thermally poor conductor layer, and 6 a molten resin supplied thereon.
第１図の熱不良導体層５として、厚み250μの
マイラー（ポリエチレンテレフタレートの商標
名、熱伝導率７×10-4cal/cm・sec・℃）フイルム
を使用し、この上に220℃に溶融したポリプロピ
レン樹脂を供給し、油圧により上プラテンを降下
させプレスして成形品を得た。この時の金型温度
は70℃である。 As the thermally defective conductor layer 5 in Fig. 1, a Mylar (trade name of polyethylene terephthalate, thermal conductivity: 7 x 10 -4 cal/cm・sec・℃) film with a thickness of 250 μm is used, and the film is melted at 220°C. The polypropylene resin was supplied, and the upper platen was lowered and pressed using hydraulic pressure to obtain a molded product. The mold temperature at this time is 70°C.
これにより、外側底部（第２図、Ａ部）を含め
成形品全面にわたつて光沢不良、シワなどのコー
ルドマークのない外観良好な成形品を得た。 As a result, a molded product with a good appearance and no cold marks such as poor gloss or wrinkles was obtained over the entire surface of the molded product, including the outer bottom (part A in FIG. 2).
比較例 １
実施例１で、マイラーフイルムを除き他は実施
例１と同様にして成形したところ、成形品外側底
部（第２図Ａ部）に光沢むら、小ジワなどのコー
ルドマークが発生し、外観の著しく不良な成形品
が得られた。Comparative Example 1 When molding was performed in the same manner as in Example 1 except for the Mylar film, cold marks such as uneven gloss and small wrinkles occurred on the outer bottom of the molded product (section A in Figure 2). A molded product with a significantly poor appearance was obtained.
実施例 ２
実施例１で、マイラーフイルムを使用する代り
に、下金型面上をポリフロン（四弗化エチレン樹
脂の商標名、熱伝導率６×10-4cal/cm・sec・℃）
で厚み250μにコートし、この上に245℃に溶融し
たポリプロピレン樹脂を供給し、金型温度は80℃
とし、他は全て実施例１と同様にして成形品を得
た。Example 2 In Example 1, instead of using Mylar film, polyflon (trade name of tetrafluoroethylene resin, thermal conductivity 6×10 -4 cal/cm・sec・℃) was used on the lower mold surface.
Polypropylene resin molten at 245°C is supplied on top of this to a thickness of 250μ, and the mold temperature is 80°C.
A molded article was obtained in the same manner as in Example 1 in all other respects.
得られた成形品はコールドマークはなく、外観
の良好なものであつた。 The obtained molded product had no cold marks and had a good appearance.
比較例 １
実施例２で、下金型面上をポリフロンでコート
しなかつた。それ以外は全て実施例２と同様にし
てポリプロピレン成形品を得た。Comparative Example 1 In Example 2, the lower mold surface was not coated with Polyflon. A polypropylene molded article was obtained in the same manner as in Example 2 in all other respects.
この成形品の外側底部、即ち、第２図Ａ部にコ
ールドマークが発生し、外観不良な成形品となつ
た。 Cold marks were generated on the outer bottom of this molded product, ie, part A in FIG. 2, resulting in a molded product with poor appearance.
実施例 ３
実施例１で、マイラーフイルムを使用する代り
に、下金型面上をスミセラム（セラミツクの商標
名、熱伝導率２×10-3cal/cm・sec・℃）で厚み
300μにコートし、この上に245℃に溶融したポリ
プロピレン樹脂をおき、金型温度90℃とし、他は
全て実施例１と同様にして成形品を得た。Example 3 In Example 1, instead of using Mylar film, the surface of the lower mold was coated with Sumiceram (trade name of Ceramic, thermal conductivity 2×10 -3 cal/cm・sec・℃).
A molded article was obtained in the same manner as in Example 1 except that a polypropylene resin molten at 245°C was placed on top of the 300μ coating and the mold temperature was 90°C.
得られた成形品にコールドマークはなく、外観
良好であつた。 The obtained molded product had no cold marks and had a good appearance.
比較例 ３
実施例３で、下金型面上をスミセラムでコート
しなかつた。それ以外は全て実施例３と同様にし
てポリプロピレン成成形品を得た。この成形品の
外側底部、即ち、第２図Ａ部にコールドマークが
発生し、外観不良な成形品となつた。Comparative Example 3 In Example 3, the lower mold surface was not coated with Sumiceram. A polypropylene molded product was obtained in the same manner as in Example 3 except for the above. Cold marks were generated on the outer bottom of this molded product, ie, part A in FIG. 2, resulting in a molded product with poor appearance.
第１図は、本発明の実施状態を示す、プラテン
に取付けたプレス成形金型部の略断面図である。
第２図は、本発明方法によつて得られる成形品の
斜視図である。
１：プレス機の上プラテン、２：プレス機の下
プラテン、３：上金型、４：下金型、５：熱不良
導体層、６：溶融樹脂、Ａ：外側底部。
FIG. 1 is a schematic cross-sectional view of a press molding die attached to a platen, showing an embodiment of the present invention.
FIG. 2 is a perspective view of a molded article obtained by the method of the present invention. 1: Upper platen of press machine, 2: Lower platen of press machine, 3: Upper mold, 4: Lower mold, 5: Heat defective conductor layer, 6: Molten resin, A: Outer bottom part.
Claims (1)
に供給し加圧、冷却して成形品を得るに際し、供
給された溶融樹脂が加圧される前から接する金型
の部分を含む面を熱伝導率が６×10-3cal/cm・se
ｃ・℃以下で、厚さが200〜500μの熱不良導体層で
覆つておくことを特徴とする熱可塑性樹脂のプレ
ス成形方法。1. When supplying molten polypropylene resin onto a mold, pressurizing it, and cooling it to obtain a molded product, the thermal conductivity of the surface including the part of the mold that comes into contact with the supplied molten resin before it is pressurized. is 6×10 -3 cal/cm・se
A method for press molding a thermoplastic resin, the method comprising: covering the material with a thermally poor conductor layer having a thickness of 200 to 500 μm at a temperature of 200 μm to 500 μm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21306382A JPS59103714A (en) | 1982-12-03 | 1982-12-03 | Press forming process of thermoplastic resin |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21306382A JPS59103714A (en) | 1982-12-03 | 1982-12-03 | Press forming process of thermoplastic resin |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59103714A JPS59103714A (en) | 1984-06-15 |
| JPH0561085B2 true JPH0561085B2 (en) | 1993-09-03 |
Family
ID=16632912
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP21306382A Granted JPS59103714A (en) | 1982-12-03 | 1982-12-03 | Press forming process of thermoplastic resin |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59103714A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4806296A (en) * | 1987-08-19 | 1989-02-21 | The Dow Chemical Company | Process of modifying polymers to produce a more readily paintable surface |
| DE68921778T2 (en) * | 1988-03-30 | 1995-12-07 | Gen Electric | Multi-layer composite structure for molding on hot surfaces. |
| EP0437345A3 (en) * | 1990-01-10 | 1992-08-19 | Taiyo Manufacturing Works Co., Ltd. | Mold used for fabricating thermoplastic resin articles |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS49117559A (en) * | 1973-03-15 | 1974-11-09 | ||
| JPS5087151A (en) * | 1973-12-05 | 1975-07-14 |
-
1982
- 1982-12-03 JP JP21306382A patent/JPS59103714A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS49117559A (en) * | 1973-03-15 | 1974-11-09 | ||
| JPS5087151A (en) * | 1973-12-05 | 1975-07-14 |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59103714A (en) | 1984-06-15 |
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