JP3792094B2 - Molding - Google Patents

Description

（但し、式中、Ｒ¹ 〜Ｒ⁴ は水素原子またはアルキル基、ｎは１以上の整数をそれぞれ表す）
（Ｂ）フェノール樹脂および
（Ｃ）次の構造式で示されるウレア系硬化促進剤
【化６】

を必須成分とすることを特徴とするエポキシ樹脂組成物である。また、このエポキシ樹脂組成物を成形硬化させることによって得られる成形品である。
【０００７】
以下、本発明を詳細に説明する。
【０００８】
本発明に用いる（Ａ）エポキシ樹脂としては、前記化５で示されたものが使用されるが、この（Ａ）エポキシ樹脂には、ｏ−クレゾールノボラック型エポキシ樹脂、ビフェニル系エポキシ樹脂、ジシクロペンタジエン系樹脂、その他の一般に公知とされているエポキシ樹脂を併用することができる。
【０００９】
本発明に用いる（Ｂ）フェノール樹脂としては、前記（Ａ）のエポキシ樹脂のエポキシ基と反応し得るフェノール性水酸基を分子中に２個以上有するものであれば特に制限されない。具体的な化合物として、例えば、
【化７】

（但し、式中、ｎは１以上の整数を表す）
【化８】

（但し、式中、ｎは１以上の整数を表す）
【化９】

（但し、式中、ｎは１以上の整数を表す）
【化１０】

（但し、式中、ｎは１以上の整数を表す）
等が挙げられ、これらは単独または２種以上混合して使用することができる。
【００１０】
本発明に用いる（Ｃ）ウレア系硬化促進剤としては、化６を挙げたが、メチル基の位置は２つのウレア官能基に対してメタ位にあることが好ましい。また、（Ｃ）ウレア系硬化促進剤はそれ単独で使用することが最も望ましいが、他の公知の硬化促進剤、例えばリン系硬化促進剤、イミダゾール系硬化促進剤、ＤＢＵ系硬化促進剤などと併用混合して使用することができる。
【００１１】
また、本発明のエポキシ樹脂組成物には、必要に応じて、シリカ粉末、タルク、ガラス繊維をはじめとする無機質充填剤を使用することができるが、精密部品用等といった小さな対象に対しては、粉体で最大粒径１００μｍ以下のもの、繊維物質であれば細大繊維長３００μｍ以下のものを用いることが望ましい。
【００１２】
本発明のエポキシ樹脂組成物は、前述した特定のエポキシ樹脂、フェノール樹脂、特定のウレア系硬化促進剤を必須成分とするが、本発明の目的に反しない限度において、また必要に応じて、上記の各種充填剤および天然ワックス類や合成ワックス類等の離型剤、三酸化アンチモン、ブロモ化エポキシ樹脂等の難燃剤、カーボンブラック等の着色剤、ゴム系やシリコーン系ポリマーの低応力付与剤、アミン変性およびエポキシ変性シリコーンオイル等のカップリング剤等を適宜添加配合することができる。
【００１３】
本発明のエポキシ樹脂組成物を成形材料として調製する場合の一般的な方法は、前述したエポキシ樹脂、フェノール樹脂、特定のウレア系硬化促進剤および各種充填剤、その他の成分を配合し、ミキサー等によって十分均一に混合し、さらに熱ロールまたはニーダ等により加熱溶融混合処理を行い、ついで冷却固化させ適当な大きさに粉砕して樹脂組成物（成形材料）とすることができる。こうして得られた樹脂組成物の成形方法としては射出成形をターゲットとしているが、移送成形や圧縮成形等による成形も可能である。
【００１４】
こうして得られた成形品は、エポキシ樹脂成形材料としての機械的強度や寸法精度、耐熱性等の特性の他に、その特徴ある硬化挙動から、成形安定性、寸法安定性等の優れた特性が得られる。
【００１５】
【作用】
本発明のエポキシ樹脂組成物およびその成形品は、前述したエポキシ樹脂組成物に、硬化促進剤として特定のウレア樹脂を用いることによって、常温では殆ど反応が進まず、射出成形機のシリンダー内の温度で初めて溶融しはじめ、金型内に注入され金型内の高い成形温度（例えば１８０℃）になると著しく反応が進むという、射出成形に非常に適した樹脂組成物が得られたものである。またこの樹脂組成物を用いた成形品は、その特徴ある硬化挙動から、成形安定性、寸法安定性、寸法精度の優れた特性が得られる。また、この樹脂組成物は保存安定性などの点でも既存のエポキシ樹脂にはみられないような優れた特性を有するものである。
【００１６】
【実施例】
次に本発明を実施例によって具体的に説明する。本発明はこれらの実施例によって限定されるものではない。また以下の実施例および比較例において「％」とは「重量％」を意味する。
【００１７】
実施例１
最大粒径１００μｍ以下の溶融シリカ粉末および結晶シリカ粉末をあわせて８３．５％、化５に示したエポキシ樹脂７．０％、前記の化１０のフェノールノボラック樹脂４．０％、前記の化６のウレア系硬化促進剤０．３％、テトラブロモビスフェノールＡ型エポキシ樹脂１．４％、カルナバワックス類０．２％、カーボンブラック０．３％、三酸化アンチモン２．０％、およびカップリング剤、低応力添加剤等のシリコーンオイル１．３％を常温で混合し、さらに９０〜１１０℃で溶融混練した後、冷却および粉砕して成形材料を製造した。
【００１８】
実施例２
最大粒径１００μｍ以下の溶融シリカ粉末８６．５％、化５に示したエポキシ樹脂５．５％、前記化７のフェノールノボラック樹脂３．３％、前記の化６のウレア系硬化促進剤０．２％、テトラブロモビスフェノールＡ型エポキシ樹脂１．０％、カルナバワックス類０．２％、カーボンブラック０．３％、三酸化アンチモン１．８％、およびカップリング剤、低応力添加剤等のシリコーンオイル１．２％を常温で混合し、さらに９０〜１１０℃で溶融混練した後、冷却および粉砕して成形材料を製造した。
【００１９】
比較例１
最大粒径１００μｍ以下の溶融シリカ粉末８３．５％、化５に示したエポキシ樹脂７．０％、前記の化１０のフェノールノボラック樹脂４．０％、イミダゾール硬化促進剤０．３％、テトラブロモビスフェノールＡ型エポキシ樹脂１．４％、カルナバワックス類０．２％、カーボンブラック０．３％、三酸化アンチモン２．０％、およびカップリング剤、低応力添加剤等のシリコーンオイル１．３％を常温で混合し、さらに９０〜１１０℃で溶融混練した後、冷却および粉砕して成形材料を製造した。
【００２０】
比較例２
最大粒径１００μｍ以下の溶融シリカ粉末８３．５％、ビフェニル型エポキシ樹脂７．０％、前記の化１０のフェノールノボラック樹脂４．０％、トリフェニルフォスフィン系硬化促進剤０．３％、テトラブロモビスフェノールＡ型エポキシ樹脂１．４％、カルナバワックス類０．２％、カーボンブラック０．３％、三酸化アンチモン２．０％、およびカップリング剤、低応力添加剤等のシリコーンオイル１．３％を常温で混合し、さらに９０〜１１０℃で溶融混練した後、冷却および粉砕して成形材料を製造した。
【００２１】
こうして製造した成形材料を用い、その１７５℃における流動性および硬化挙動、機械的強度について諸試験を行ったので、結果を表１に示す。
【００２２】
【表１】

＊１：ＥＭＭＩ−Ｉ−６６に準じて１７５℃におけるスパイラルフローを測定した。
【００２３】
＊２：１７５℃に保たれた熱板上で一定量の成形材料を直径４〜５ｃｍの円状に広げ、一定速度で練り合わせたとき、試料が増粘し、最終的に粘りのなくなった時間を計測した。
【００２４】
＊３：ラボプラストミルにおいて材料を混練し、混練トルクの変化により硬化時間を測定した。測定温度は１００℃、１４０℃、１８０℃の３段階とした。
【００２５】
＊４：ＪＩＳ−Ｋ−６９１１に準じて測定した。
【００２６】
＊５：熱分析装置を用い、昇温速度１０℃／分で測定した。
【００２７】
【発明の効果】
以上の説明および表１から明らかなように、本発明のエポキシ樹脂組成物および成形品によれば、成形温度での硬化性を維持したまま、その温度以下で、溶融粘度の低い状態を維持することができ、その結果、放熱性を維持したまま成形性を向上させる成形材料およびそれを用いて熱硬化性樹脂成形品を得ることができるのである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an epoxy resin composition excellent in moldability and a molded product thereof.
[0002]
[Prior art]
In recent years, metal parts making up machines and devices are shifting to molded parts made of resin from the viewpoints of weight reduction and workability, and in that case, molded products by injection molding that are superior in terms of mass production have become mainstream. ing. However, when targeting ultra-precision parts, as a practical matter, it is difficult for plastic molded parts to reach the level of metal parts in terms of heat resistance, dimensional accuracy, molding stability, strength, etc. Few things were enough to satisfy. In addition, many epoxy resin molding materials on the market are suitable for transfer molding, and are limited to molding materials suitable for injection molding. Epoxy resins for injection molding especially for ultra-precision parts There are few molding materials on the market.
[0003]
[Problems to be solved by the invention]
Molding with a thermoplastic resin may be superior to a thermosetting resin in terms of molding stability and dimensional accuracy due to the characteristics of the molding method. On the other hand, thermosetting resins are often superior in terms of long-term heat resistance levels and hot mechanical strength (specifically, creep characteristics) in molded parts.
[0004]
Therefore, in injection molding, while maintaining the molding stability and dimensional accuracy equivalent to those of thermoplastic resins, the hot characteristics of epoxy resin (thermosetting resin) molding materials (long-term heat resistance level and heat) It has been desired to develop a molding material that makes the most of the mechanical strength (specifically, creep characteristics) at the time. In addition, an injection molding material that satisfies these requirements is not limited to the molding method, and can be molded under a wide range of molding conditions, and an effect of excellent storage stability of the molding material can be expected.
[0005]
[Means for Solving the Problems]
As a result of earnest research to achieve the above object, the present inventor used a specific urea resin as a curing accelerator with respect to a specific epoxy resin, so that the reaction hardly proceeded at room temperature. A resin composition very suitable for injection molding was obtained, which began to melt for the first time at the temperature in the cylinder, and then reacted significantly when injected into the mold and reached the molding temperature. A molded article using this resin composition can obtain excellent characteristics such as molding stability and dimensional accuracy from its characteristic curing behavior. Furthermore, this resin composition has been found to have excellent properties not found in existing epoxy resin compositions in terms of storage stability and the like, and the present invention has been completed.
[0006]
That is, the present invention
(A) a polyfunctional epoxy resin represented by the following general formula:
[Chemical formula 5]

(In the formula, R ^{1 to} R ⁴ are each a hydrogen atom or an alkyl group, and n is an integer of 1 or more.)
(B) Phenol resin and (C) Urea curing accelerator represented by the following structural formula

Is an epoxy resin composition characterized in that it is an essential component. Moreover, it is a molded article obtained by molding and curing this epoxy resin composition.
[0007]
Hereinafter, the present invention will be described in detail.
[0008]
As the (A) epoxy resin used in the present invention, the one shown in the chemical formula 5 is used. As the (A) epoxy resin, o-cresol novolac type epoxy resin, biphenyl type epoxy resin, dicyclo A pentadiene resin and other generally known epoxy resins can be used in combination.
[0009]
The (B) phenol resin used in the present invention is not particularly limited as long as it has two or more phenolic hydroxyl groups in the molecule that can react with the epoxy group of the epoxy resin (A). As a specific compound, for example,
[Chemical 7]

(In the formula, n represents an integer of 1 or more)
[Chemical 8]

(In the formula, n represents an integer of 1 or more)
[Chemical 9]

(In the formula, n represents an integer of 1 or more)
Embedded image

(In the formula, n represents an integer of 1 or more)
These may be used alone or in combination of two or more.
[0010]
As the (C) urea-based curing accelerator used in the present invention, Chemical Formula 6 is mentioned, but the methyl group is preferably located in the meta position with respect to two urea functional groups. The (C) urea curing accelerator is most preferably used alone, but other known curing accelerators such as phosphorus curing accelerators, imidazole curing accelerators, DBU curing accelerators, etc. Can be used in combination.
[0011]
In addition, the epoxy resin composition of the present invention can use inorganic fillers such as silica powder, talc, and glass fiber as necessary, but for small objects such as for precision parts. It is desirable to use a powder having a maximum particle size of 100 μm or less, or a fiber material having a fine fiber length of 300 μm or less.
[0012]
The epoxy resin composition of the present invention contains the above-described specific epoxy resin, phenol resin, and specific urea curing accelerator as essential components, but as long as it is not contrary to the object of the present invention, and if necessary, Various fillers and mold release agents such as natural waxes and synthetic waxes, flame retardants such as antimony trioxide and brominated epoxy resins, colorants such as carbon black, low stress imparting agents for rubber and silicone polymers, Coupling agents such as amine-modified and epoxy-modified silicone oils can be appropriately added and blended.
[0013]
When preparing the epoxy resin composition of the present invention as a molding material, the above-mentioned epoxy resin, phenol resin, specific urea-based curing accelerator and various fillers, other ingredients are blended, a mixer, etc. The mixture can be sufficiently uniformly mixed, and further heated and mixed with a hot roll or a kneader, then cooled and solidified, and pulverized to an appropriate size to obtain a resin composition (molding material). As a molding method of the resin composition thus obtained, injection molding is a target, but molding by transfer molding or compression molding is also possible.
[0014]
The molded product thus obtained has excellent properties such as molding stability and dimensional stability due to its characteristic curing behavior in addition to the properties such as mechanical strength, dimensional accuracy and heat resistance as an epoxy resin molding material. can get.
[0015]
[Action]
The epoxy resin composition of the present invention and the molded product thereof use the specific urea resin as a curing accelerator in the above-described epoxy resin composition, so that the reaction hardly proceeds at room temperature, and the temperature in the cylinder of the injection molding machine. Thus, a resin composition that is very suitable for injection molding is obtained, which begins to melt for the first time and is poured into a mold and reaches a high molding temperature (for example, 180 ° C.), and the reaction proceeds remarkably. Moreover, the molded article using this resin composition can obtain the characteristics excellent in molding stability, dimensional stability, and dimensional accuracy from its characteristic curing behavior. In addition, this resin composition has excellent characteristics that are not found in existing epoxy resins in terms of storage stability.
[0016]
【Example】
Next, the present invention will be specifically described with reference to examples. The present invention is not limited by these examples. In the following examples and comparative examples, “%” means “% by weight”.
[0017]
Example 1
83.5% of the combined fused silica powder and crystalline silica powder having a maximum particle size of 100 μm or less, 7.0% of the epoxy resin shown in Chemical Formula 5, 4.0% of the phenol novolak resin of Chemical Formula 10 and Chemical Formula 6 Urea-based curing accelerator 0.3%, tetrabromobisphenol A type epoxy resin 1.4%, carnauba wax 0.2%, carbon black 0.3%, antimony trioxide 2.0%, and coupling agent Then, 1.3% of a silicone oil such as a low-stress additive was mixed at room temperature, melt-kneaded at 90 to 110 ° C., and then cooled and ground to produce a molding material.
[0018]
Example 2
86.5% of fused silica powder having a maximum particle size of 100 μm or less, 5.5% of epoxy resin shown in Chemical formula 5, 3.3% of phenol novolak resin of Chemical formula 7, and urea curing accelerator of Chemical formula 6 2%, tetrabromobisphenol A type epoxy resin 1.0%, carnauba wax 0.2%, carbon black 0.3%, antimony trioxide 1.8%, and silicone such as coupling agent and low stress additive Oil 1.2% was mixed at room temperature, melt-kneaded at 90 to 110 ° C., then cooled and pulverized to produce a molding material.
[0019]
Comparative Example 1
83.5% of fused silica powder having a maximum particle size of 100 μm or less, 7.0% of epoxy resin shown in Chemical formula 4, 4.0% of phenol novolak resin of Chemical formula 10 above, 0.3% of imidazole curing accelerator, tetrabromo Bisphenol A type epoxy resin 1.4%, carnauba waxes 0.2%, carbon black 0.3%, antimony trioxide 2.0%, and silicone oil 1.3% for coupling agents, low stress additives, etc. Were mixed at room temperature, melt-kneaded at 90 to 110 ° C., cooled and pulverized to produce a molding material.
[0020]
Comparative Example 2
83.5% fused silica powder having a maximum particle size of 100 μm or less, 7.0% biphenyl type epoxy resin, 4.0% phenol novolak resin of the above chemical formula 10, 0.3% triphenylphosphine-based curing accelerator, tetra Bromobisphenol A type epoxy resin 1.4%, carnauba waxes 0.2%, carbon black 0.3%, antimony trioxide 2.0%, and silicone oil 1.3 such as coupling agent and low stress additive % Was mixed at room temperature, melt-kneaded at 90 to 110 ° C., then cooled and pulverized to produce a molding material.
[0021]
Various tests were conducted on the fluidity, curing behavior, and mechanical strength at 175 ° C. using the molding material thus produced, and the results are shown in Table 1.
[0022]
[Table 1]

* 1: Spiral flow at 175 ° C. was measured according to EMMI-I-66.
[0023]
* 2: When a certain amount of molding material is spread in a circle of 4-5 cm in diameter on a hot plate maintained at 175 ° C. and kneaded at a constant speed, the time when the sample thickened and finally disappeared Was measured.
[0024]
* 3: The materials were kneaded in a lab plast mill, and the curing time was measured by changing the kneading torque. The measurement temperature was set at three stages of 100 ° C., 140 ° C., and 180 ° C.
[0025]
* 4: Measured according to JIS-K-6911.
[0026]
* 5: Measured using a thermal analyzer at a heating rate of 10 ° C./min.
[0027]
【The invention's effect】
As is apparent from the above description and Table 1, according to the epoxy resin composition and molded article of the present invention, the melt viscosity is maintained at a temperature lower than that temperature while maintaining the curability at the molding temperature. As a result, it is possible to obtain a molding material that improves moldability while maintaining heat dissipation and a thermosetting resin molded article using the molding material.

Claims (1)

(A) a polyfunctional epoxy resin represented by the following general formula:

(In the formula, R ^{1 to} R ⁴ are each a hydrogen atom or an alkyl group, and n is an integer of 1 or more.)
(B) a phenolic resin and (C) a urea-based curing accelerator represented by the following structural formula

A molded article obtained by molding and curing an epoxy resin composition containing as an essential component.