【発明の詳細な説明】
本発明は粉末状エポキシ樹脂組成物の製造方法に関す
る。粉末状エポキシ樹脂組成物は従来無公害、省資源、
省エネルギー型の塗料、絶縁材料、合固着材料として巾
広く使用されている。これ等粉末状エポキシ樹脂組成物
に使用されているエポキシ樹脂の一つとして結晶性エポ
キシ樹脂がある。この結晶性エポキシ樹脂は通常使用さ
れている固体状エポキシ樹脂たとえばビスフェノールＡ
型、ビスフェノールＦ型、ノボラック型エポキシ樹脂に
比し、溶融時の粘度が著しく低いという特性を有し、こ
れがためプリプレグやコイル等の含浸固着に用いられて
いる。しかしながらこの結晶性エポキシ樹脂は他の成分
たとえば硬化剤やその他の添加剤等と溶融混合すると結
晶性がなくなり、融点降下が生じ、常温で液状となった
り、固体であっても常温付近でブロッキングを生じ易
く、粉末組成物として用いることが非常に困難であっ
た。このため従来結晶性エポキシ樹脂を用いる場合は結
晶性エポキシ樹脂及びその他の成分たとえば硬化剤等を
細かく微粉砕した後乾式で混合して使用し、溶融混合は
行なっていなかった。この乾式混合でもエポキシ樹脂や
硬化剤は均一に混合された状態となっているが、これに
外力が加わるとたとえば運搬時などの振動により偏析が
起こり、得られる樹脂硬化物の物性にバラツキが生じる
難点がある。また特に一度使用した余剰物を再使用する
とやはり得られる樹脂硬化物の特性に大きなバラツキを
生じ、時には硬化が生じない場合もあった。本発明者は
結晶性エポキシ樹脂を用いた粉末状組成物の上記利点と
難点に注目し、上記利点を毫も損うことなく難点だけを
うまく解消出来る方法を開発すべく研究を続けて来た
が、この研究に於いて結晶性エポキシ樹脂と硬化剤必要
に応じその他の添加剤と共に乾式混合した後、これ等を
圧着し、次いで粉砕し分級するときは、所期の目的を達
成出来ることを見出し、ここに本発明を完成するに至っ
た。すなわち本発明は、３０℃で固体の結晶性エポキシ
樹脂と、同温度で固体の硬化剤とを粉砕し乾式混合した
後、各成分の融点以下の温度で圧着せしめ、次いで粉砕
し分級することを特徴とする粉末状エポキシ樹脂組成物
の製造方法に係るものである。本発明法に依ると結晶性
エポキシ樹脂、硬化剤及び必要に応じその他の添加剤を
含有して成る組成物を乾式混合した後圧着し、これを再
び粉砕し分級すると、実に驚くべきことに溶融混合して
いないにもかかわらず従来の如く振動等の外力が加わっ
ても、或いは余剰分を再使用しても、全く硬化物特性に
バラツキが生じることなくほぼ均質な樹脂硬化物が収得
出来、従来の難点をうまく解消出来る。本発明で使用す
る結晶性エポキシ樹脂としては３０℃で固体の結晶性エ
ポキシ樹脂であり、従来この分野で使用されて来た所謂
結晶性エポキシ樹脂が広く使用される。特に本発明に於
いては３０℃で固体で且つその融点よりも１０℃高い温
度での溶融粘度が５ポイズ以下であるエポキシ樹脂が好
ましい。これ等の具体例としてはたとえばトリグリシジ
ルイソシアヌレート、４，４′−ビス（２，３−エポキ
シプロポキシ）−３，３′，５，５′−テトラメチルビ
フェニル、ジグリシジルテレフタレート、ジグリシジル
ハイドロキノン等を例示出来る。更に詳しくは、たとえ
ば下記一般式（Ｉ）で表わされるジグリシジルハイドロ
キノンを代表例として説明すると、次の通りである。
ジグリシジルハイドロキノンは式（Ｉ）において繰り返
し単位数ｎ＝０の化合物であり、結晶性を有するもので
ある。しかしながら本発明に於いては上記ｎが１〜５程
度の化合物や、末端がエポキシ化されていない化合物を
２０％以下好ましくは５％以下含んでいても良い。本発
明結晶性エポキシ樹脂には、また非結晶性で固形状のエ
ポキシ樹脂たとえば固形ビスフェノールＡ型、ビスフェ
ノールＦ型、ノボラック型エポキシ樹脂を一部通常５〜
８０重量％好ましくは５〜３０重量％程度含有させるこ
とが出来る。これ等非結晶性エポキシ樹脂を一部含有さ
せることにより、塗膜の可とう性の向上、溶融粘度の調
整、耐熱性の向上という利点が生じる。これ等非結晶性
エポキシ樹脂は軟化点としては１３０℃程度以下のもの
が好ましく、軟化点があまり高くなりすぎると圧着時に
圧着し難くなる傾向がある。これ等非結晶性エポキシ樹
脂の具体例を挙げるとエポキシ当量が４００〜２０００
のビスフェノールＡ型，ビスフェノールＦ型エポキシ樹
脂や、５核体以上のフェノールノボラックのポリグリシ
ジルエーテル等である。本発明に於いて使用する硬化剤
は３０℃で固体のものであるかぎり特に制限されず、広
い範囲で各種の硬化剤が使用出来、たとえば代表例とし
てアミン、アミンアダクト、ポリアミド、ポリアミドア
ダクト、多価酸、酸無水物、多価フェノール、イミダゾ
ール類、イミダゾリン類、ジシアンジアミド及びその誘
導体、三フッ化ホウ素及びその誘導体、ジヒドラジド類
等を挙げることが出来る。また本発明に於いては必要に
応じて各種の添加剤を配合することが出来るが、これ等
添加剤は固体であることが望ましいが、全体の１０重量
％以下好ましくは５重量％以下程度ならば液体のもので
あっても良い。但し液体の場合は硬化剤と予め溶融混合
しておくとより均一に分散し、良好な効果が期待できる
ので特に好ましい。これ等添加剤としてはこの種粉末状
エポキシ樹脂組成物に使用されて来た各種の添加剤がい
ずれも使用出来、たとえば三級アミン、イミダゾール
類、三フッ化ホウ素、ジシアンジアミド及びその誘導体
の如き硬化促進剤、タルク、ケイ砂、シリカ、炭酸カル
シウム、硫酸バリウムの如き充填剤、カーボンブラッ
ク、ベンガラ、酸化チタン、酸化クロム、シアニンブル
ー、シアニングリーンの如き顔料、その他流れ調整剤等
を例示出来る。これ等添加剤の配合割合は、その種類や
用途に応じて変化するが、通常０．５〜２００重量％好
ましくは０．５〜５０重量％程度である。本発明法実施
に際しては先ず上記各成分、更に詳しくは結晶性エポキ
シ樹脂、硬化剤及び必要に応じ他の添加剤を粉砕する。
粉砕手段は何等制限されず各種の手段がいずれも有効に
適用される。粉砕の程度としては通常平均粒径が１０〜
１００μｍ程度であるが、最終目的物たるエポキシ樹脂
組成物よりも充分に細かくなるような粒度たとえば最終
目的物組成物の平均粒径が２００μｍならば上記各成分
は平均粒径が２０〜５０μｍ程度に粉砕するのが好まし
い。また特にこの際（平均粒径２０〜５０μｍの中か
ら）１００μｍ以上の大粒を除去すると各成分の分散状
態がより一層均一となり好ましい。粉砕された各成分は
次いで乾式混合されるが、この際の手段としても特に制
限されず各種の手段がいずれも使用出来、たとえば高速
攪拌型ミキサー、Ｖプレンダー等を代表例として挙げる
ことが出来る。この乾式混合により各成分は充分均一に
混合される。次いでこの混合物を圧着せしめる。この圧
着工程は本発明に於いては極めて重要であり、結晶性エ
ポキシ樹脂、硬化剤及び必要に応じ使用されるその他の
添加剤を圧着しておたがいに結合せしめる。この際の圧
着された状態とは、圧着物が最悪でも、容易に手で粉々
にくずすことが出来ないような状態を指し、本発明に於
いては上記の如き状態となるかぎり、圧着操作は何等限
定されないが、通常２０〜５０℃程度で５０〜３００ｋ
ｇ／ｃｍ２程度の条件で行なう。特に該圧着工程に於い
ては結晶性エポキシ樹脂及び硬化剤の融点より低い温度
で圧着工程を行なうことが大切であり、決してこれ等が
溶融しないようにする必要がある。最後に圧着したもの
を粉砕し、分級して最終目的物たる本発明組成物を得
る。この際の粉砕並びに分級いずれも従来公知の方法で
良く、これにより７００μｍ以下の組成物とする。かく
して得られる本発明組成物は、たとえばその一粒子をと
ってみると、エポキシ樹脂粒子と硬化剤とが圧着されて
成っており、振動等の外力が作用しても何等組成に変化
が生ぜず、またたとえ再使用したとしても従来の乾式混
合した組成物の如きバラツキは全く生じない。以下に実
施例並びに比較例を示して本発明の特徴とする所をより
一層明瞭となす。
実施例１〜４
第１表に示す所定の結晶性エポキシ樹脂、硬化剤、及び
硬化促進剤を粉砕し、１２０メッシュ篩で篩別する。１
２０メッシュをパスしたものを、第１表に示す配合割合
（重量部）でヘンシェルミキサーで乾式混合する。次に
この粉体を第１表に示す条件で圧着させ、粉砕し、４０
メッシュで篩別した。得られた組成物の性状とブロッキ
ング性を第１表に併記した。
比較例１〜４
実施例と同様な配合で、乾式混合後圧着せずにロールに
て溶融混合した。得られた組成物の性状を第１表に示し
た。 DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a powdery epoxy resin composition. The powdered epoxy resin composition has conventionally been pollution-free, resource saving,
Widely used as energy-saving paints, insulating materials, and bonding materials. A crystalline epoxy resin is one of the epoxy resins used in these powdery epoxy resin compositions. This crystalline epoxy resin is a commonly used solid epoxy resin such as bisphenol A.
Type, bisphenol F type, and novolac type epoxy resin have a characteristic that the viscosity at the time of melting is remarkably low, which is why they are used for impregnating and fixing prepregs and coils. However, when this crystalline epoxy resin is melt-mixed with other components such as a curing agent and other additives, it loses its crystallinity, its melting point is lowered, it becomes liquid at room temperature, and even if it is a solid, blocking occurs near room temperature. It is easy to occur and it was very difficult to use as a powder composition. For this reason, when a crystalline epoxy resin has been used conventionally, the crystalline epoxy resin and other components such as a curing agent are finely pulverized and then mixed and used in a dry system, and melt mixing is not performed. Even in this dry mixing, the epoxy resin and the curing agent are in a uniformly mixed state, but when an external force is applied to this, segregation occurs due to vibration during transportation, for example, and the physical properties of the obtained resin cured product vary. There are difficulties. In particular, when the surplus used once is reused, there is a large variation in the characteristics of the cured resin product obtained, and sometimes the curing does not occur. The present inventor has focused on the above-mentioned advantages and disadvantages of a powdery composition using a crystalline epoxy resin, and has continued research to develop a method capable of successfully solving only the above-mentioned advantages without compromising the advantages. However, in this research, when the crystalline epoxy resin and the curing agent were dry-mixed with other additives as required, and then pressure-bonded, and then crushed and classified, the intended purpose could be achieved. The present invention has been completed here. That is, according to the present invention, a crystalline epoxy resin which is solid at 30 ° C. and a hardener which is solid at the same temperature are pulverized and dry-mixed, and then pressure-bonded at a temperature below the melting point of each component, and then pulverized and classified. The present invention relates to a method for producing a characteristic powdery epoxy resin composition. According to the method of the present invention, a composition containing a crystalline epoxy resin, a curing agent and, if necessary, other additives is dry-mixed, then pressure-bonded, and then crushed again and classified, and it is surprisingly melted. Even if an external force such as vibration is applied as in the past even if they are not mixed, or even if the surplus is reused, it is possible to obtain a substantially homogeneous resin cured product with no variation in the cured product properties. You can successfully solve the conventional difficulties. The crystalline epoxy resin used in the present invention is a crystalline epoxy resin that is solid at 30 ° C., and so-called crystalline epoxy resins that have been used in this field conventionally are widely used. Particularly preferred in the present invention is an epoxy resin which is solid at 30 ° C. and has a melt viscosity of 5 poise or less at a temperature 10 ° C. higher than its melting point. Specific examples of these include triglycidyl isocyanurate, 4,4'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'-tetramethylbiphenyl, diglycidyl terephthalate, diglycidyl hydroquinone and the like. Can be illustrated. More specifically, for example, diglycidyl hydroquinone represented by the following general formula (I) will be described as a representative example. Diglycidyl hydroquinone is a compound having the number of repeating units n = 0 in the formula (I) and has crystallinity. However, in the present invention, 20% or less, preferably 5% or less, of the compound in which n is about 1 to 5 or the compound in which the terminal is not epoxidized may be contained. The crystalline epoxy resin of the present invention may be a non-crystalline solid epoxy resin such as solid bisphenol A type, bisphenol F type or novolac type epoxy resin, which is usually contained in an amount of 5 to 5%.
80 wt%, preferably 5 to 30 wt% can be contained. The partial incorporation of these non-crystalline epoxy resins brings about the advantages of improving the flexibility of the coating film, adjusting the melt viscosity, and improving the heat resistance. These non-crystalline epoxy resins preferably have a softening point of about 130 ° C. or lower, and if the softening point becomes too high, it tends to be difficult to perform pressure bonding during pressure bonding. Specific examples of these non-crystalline epoxy resins have an epoxy equivalent of 400 to 2000.
Bisphenol A type and bisphenol F type epoxy resins, and polyglycidyl ethers of phenol novolac having 5 or more nuclides. The curing agent used in the present invention is not particularly limited as long as it is solid at 30 ° C., and various curing agents can be used in a wide range, for example, amine, amine adduct, polyamide, polyamide adduct, polyadduct Examples thereof include carboxylic acids, acid anhydrides, polyhydric phenols, imidazoles, imidazolines, dicyandiamide and its derivatives, boron trifluoride and its derivatives, and dihydrazides. Further, in the present invention, various additives can be blended as required, but it is desirable that these additives are solid, but 10% by weight or less of the total, preferably 5% by weight or less It may be liquid as well. However, in the case of a liquid, it is particularly preferable to melt-mix it with a curing agent in advance so that it can be dispersed more uniformly and a good effect can be expected. As these additives, various additives which have been used in this kind of powdery epoxy resin composition can be used. For example, a curing agent such as a tertiary amine, imidazoles, boron trifluoride, dicyandiamide and a derivative thereof can be used. Examples thereof include accelerators, fillers such as talc, silica sand, silica, calcium carbonate and barium sulfate, pigments such as carbon black, red iron oxide, titanium oxide, chromium oxide, cyanine blue and cyanine green, and flow regulators. The mixing ratio of these additives varies depending on the type and application, but is usually 0.5 to 200% by weight, preferably 0.5 to 50% by weight. In carrying out the method of the present invention, first, the above-mentioned components, more specifically, the crystalline epoxy resin, the curing agent and, if necessary, other additives are pulverized.
The crushing means is not limited in any way, and various means can be effectively applied. As the degree of pulverization, the average particle size is usually 10
The particle size is about 100 μm, but the particle size is sufficiently finer than that of the epoxy resin composition as the final target, for example, if the average particle size of the final target composition is 200 μm, the above-mentioned components have average particle sizes of about 20 to 50 μm. It is preferable to grind. Further, in this case, it is particularly preferable to remove large particles of 100 μm or more (from the average particle diameter of 20 to 50 μm) because the dispersed state of each component becomes more uniform. The pulverized components are then dry-mixed, and the means used at this time are not particularly limited and any of various means can be used. For example, a high-speed agitation mixer, a V blender and the like can be mentioned as typical examples. By this dry mixing, the respective components are mixed sufficiently uniformly. The mixture is then crimped. This crimping step is extremely important in the present invention, and the crystalline epoxy resin, the curing agent, and other additives used as necessary are crimped and bonded together. The crimped state at this time refers to a state in which the crimped object cannot be easily broken into pieces even if the crimped object is the worst, and in the present invention, the crimping operation is not performed as long as it is in the state as described above. Although not limited in any way, it is usually 50 to 300k at about 20 to 50 ° C.
It is performed under the condition of g / cm 2 . In particular, in the crimping step, it is important to carry out the crimping step at a temperature lower than the melting points of the crystalline epoxy resin and the curing agent, and it is necessary to prevent these from melting. Finally, the pressure-bonded product is pulverized and classified to obtain the composition of the present invention as the final target product. Both pulverization and classification at this time may be carried out by a conventionally known method, whereby a composition of 700 μm or less is obtained. The composition of the present invention thus obtained is, for example, when one particle is taken, the epoxy resin particle and the curing agent are pressure-bonded to each other, and no change occurs in the composition even when an external force such as vibration acts. Moreover, even if it is reused, there is no variation like the conventional dry-blended composition. The features of the present invention will be made clearer by showing Examples and Comparative Examples below. Examples 1 to 4 Predetermined crystalline epoxy resins, curing agents and curing accelerators shown in Table 1 are crushed and sieved with a 120 mesh sieve. 1
Those that pass 20 mesh are dry-mixed with a Henschel mixer at the blending ratio (parts by weight) shown in Table 1. Next, this powder was pressed under the conditions shown in Table 1 and crushed to obtain 40
It was sieved with a mesh. The properties and blocking properties of the obtained composition are also shown in Table 1. Comparative Examples 1 to 4 With the same composition as that of the examples, after dry-mixing, they were melt-mixed with a roll without pressure bonding. The properties of the obtained composition are shown in Table 1.