【発明の詳細な説明】[Detailed description of the invention]
本発明はエチレン−酢酸ビニル共重合体けん化
物を主成分とする特に繊維加工用にすぐれた接着
剤に関する。
エチレン−酢酸ビニルけん化物は耐溶剤性、剛
性、耐摩耗性にすぐれ、繊維をはじめ、ガラス、
木材、金属等の基材に対しすぐれた接着性能を示
し、ホツトメルト型接着剤として工業的に広く使
用されている。このようにエチレン−酢酸ビニル
共重合体けん化物はすぐれた幾つかの性能を有し
ているが、これが微粒子の状態、通常工業的に使
用される40乃至1000ミクロンの粉体では振動、移
動等による粒子同志の摩擦が起り、その性質上著
しく静電気を帯びやすく、そのためにエチレン−
酢酸ビニル共重合体けん化物粉末を製造する側に
おいても、また接着剤として接着に供する際にお
いても種々の障害をもたらす。すなわちエチレン
−酢酸ビニル共重合体けん化物粉末製造工程にお
いて製品を各種サイズの粒子径に篩い分ける場
合、摩擦によりエチレン−酢酸ビニル共重合体け
ん化物は容易に静電気を帯び、粒子同志が静電気
的に引き合つて一次粒子から二次粒子に、さらに
二次粒子の集合体となり極端な場合には篩い目を
全く通過しなくなり、篩い分け不能となる。また
特にエチレン−酢酸ビニル共重合体けん化物粉末
を繊維接着用に使用する場合には、接着剤粉末を
フイーダーにより布面に均一に撒布しなければな
らないが、この場合にもエチレン−酢酸ビニル共
重合体けん化物粉末の流動摩擦により静電気帯電
を起し粒子同志が付き合つて布面に均一な撒布が
できないばかりでなく、接着剤フイーダーから全
く流出しなくなるという極めて重大な障害を惹き
起す。
本発明者は上記の問題解決のため鋭意検討を重
ねた結果エチレン−酢酸ビニル共重合体けん化物
に対し、特定微量の粒径0.1ミクロン以下のγア
ルミナを添加混合することにより、前述の接着剤
としての性能をなんら低下させることなく、上記
の障害を完全に防止しうるばかりでなく、接着剤
として使用する際通常のものよりもさらに作業性
を高める効果を得て、本発明を完成させた。
本発明樹脂接着剤組成物に使用されるエチレン
−酢酸ビニル共重合体けん化物としては酢酸ビニ
ル含有率20〜35重量％、けん化度80％以上、メル
トインデツクス30〜200ｇ／10分、粒度範囲40〜
1000ミクロン程度のものが好ましい。このエチレ
ン−酢酸ビニル共重合体けん化物は例えば、エチ
レン−酢酸ビニル共重合体をあらかじめ粉砕し粉
末状でメタノール、エタノール等の低級アルコー
ル媒体中でアルカリ触媒下でけん化するか、また
はトルエン、キシレン等の溶媒に共重合体を溶解
し、これに水酸化ナトリウム、水酸化カリウムま
たはナトリウムメトキサイド等を直接または低級
アルコール溶液を添加して昇温けん化した後、多
量のアルコール中に放出してけん化物粒子を析出
せしめ、水洗、アルコール洗浄などの精製を行つ
たのち、乾燥、篩い分けて粒度を揃えるか、もし
くは洗浄工程の後で湿式篩い分けを行ない粒度を
揃えた後乾燥することによつて容易に製造されて
いる。
本発明に使用されるγアルミナはアルミニウム
を含む揮発性化合物、例えば無水塩化アルミニウ
ムを高温の酸水素焔中で加水分解することによつ
て製造されており、その結果構成はガンマ構造で
一次粒子径は約0.02ミクロンと極めて微細であ
る。
本発明樹脂接着剤組成物を得るにはγアルミナ
を前記エチレン−酢酸ビニル共重合体けん化物の
製造工程のいずれにおいてもよいから添加、均一
に混合すれば目的は達成されるが、けん化工程、
洗浄工程で添加するときは別する低級アルコー
ル中に一部の酸化アルミニウムがロスされるの
で、できるだけ乾燥前もしくは乾燥後の工程で添
加するのが好ましい。またトルエン、キシレンに
エチレン−酢酸ビニル共重合体を溶かしてけん化
する場合にはアルコールなどのけん化終了物粒子
を析出せしめる工程以後で添加する方法が好まし
い。γアルミナの添加量はエチレン−酢酸ビニル
共重合体けん化物に対して0.005〜1.0重量％で、
0.005重量％以下の添加では本発明効果が認めら
れないし、1.0重量％以上では帯電防止効果ひい
ては粉末の流れ性は充分良くなるが、接着剤とし
て使用したときの接着強度の低下が起る。また実
施例に見られるように同じアルミナであつてもα
アルミナはγアルミナと同様の用い方をしても何
らの効果も認められなかつた。
このようにして製造された本発明の樹脂接着剤
組成物はエチレン−酢酸ビニル共重合体けん化物
の本来の接着性能を損なうことなく用いられるの
は勿論のことであるが、けん化物粒子はその大小
を問わずすべて単独粒子に分離しているため、製
造工程にあつては各粒度の粒子とも各篩い目を容
易かつ迅速に通り抜けて製品の粒度分布を揃える
ことが可能となつた。
また種々の粒度分布に篩い分けた製品をたとえ
ば織布接着用として使用する際、接着剤フイーダ
ーからの接着剤粒子の流れが極めて円滑に行え、
織布面に接着剤粉末を均一に撒布することも可能
となつたので接着剤粒子が織布上で集合して分散
むらを生ずるとか、フイーダーからの供給ができ
なくなるといつた障害も完全に克服されたばかり
でなく、フイーダーからの接着剤粒子を撒布する
速度を著しく速くすることが可能となつて、織布
の加工生産性が大きく向上させられた。
このような本発明樹脂接着剤組成物の効果は本
発明に用いる超微粒子のγ酸化アルミニウムが、
通常の他の酸化アルミニウムとは性質が異なり、
電気的に正電荷を持つていると云われ、この正電
荷が樹脂類の摩擦によつて生ずる負電荷を静電気
的に完全に中和し、樹脂粒子同志の集合を防止す
る効果によるものと推定される。
次に本発明の実施例を示す。
実施例 １
酢酸ビニル含量30重量％、メルトインデツクス
100ｇ／10分のエチレン−酢酸ビニル共重合体粉
末をけん化率約95％にけん化したエチレン−酢酸
ビニル共重合体けん化物を二分し、一方はその
まゝ何も添加しない試料Ａとし、他方には0.1重
量％のアルミニウムオキサイドＣ（日本アエロジ
ル株式会社品、γアルミナ、一次粒子径５〜20ミ
リミクロン）を添加し、充分混合して試料Ｂと
し、試料ＡおよびＢについて同一条件での篩い通
り性を試験し表１の結果を得た。
表１の通り性試験の後、各層の試料について顕
微鏡観察した結果、試料Ａすなわちアルミナ無添
加品は各篩い目のサンプル共いずれも、エチレン
−酢酸ビニル共重合体けん化物粒子同志が集つて
二次粒子を生成しているのに反し、試料Ｂは各粒
子が各々、別々に分離していることが観察され、
従て試料ＡおよびＢは同一粒度分布であるにも
かゝわらず、アルミナ無添加の試料Ａは粒度分布
が粒度の大きい方に出ており間違つた粒度分布結
果を与えている。
The present invention relates to an adhesive which is particularly suitable for textile processing and whose main component is a saponified ethylene-vinyl acetate copolymer. Ethylene-vinyl acetate saponified product has excellent solvent resistance, rigidity, and abrasion resistance, and is useful for fibers, glass,
It exhibits excellent adhesion performance to base materials such as wood and metal, and is widely used industrially as a hot melt adhesive. As described above, saponified ethylene-vinyl acetate copolymer has several excellent properties, but when it is in the form of fine particles, usually industrially used powders of 40 to 1000 microns, vibrations, movement, etc. Due to its nature, friction between particles occurs, which makes them extremely susceptible to static electricity.
Various problems arise both in the production of saponified vinyl acetate copolymer powder and in the use of it as an adhesive. In other words, when the product is sieved into particles of various sizes in the manufacturing process of saponified ethylene-vinyl acetate copolymer powder, the saponified ethylene-vinyl acetate copolymer is easily charged with static electricity due to friction, and the particles are electrostatically charged. As a result, primary particles become secondary particles, which then become aggregates of secondary particles, and in extreme cases, they do not pass through the sieve at all, making it impossible to sieve. In addition, especially when saponified ethylene-vinyl acetate copolymer powder is used for fiber bonding, the adhesive powder must be uniformly spread over the fabric surface using a feeder, but in this case as well, ethylene-vinyl acetate copolymer powder must be uniformly spread over the fabric surface. Flow friction of the saponified polymer powder causes electrostatic charging, causing the particles to stick together, which not only makes it impossible to spread uniformly on the fabric surface, but also causes an extremely serious problem in that the adhesive does not flow out of the adhesive feeder at all. As a result of extensive research in order to solve the above problem, the present inventor has developed the aforementioned adhesive by adding and mixing a specific trace amount of γ alumina with a particle size of 0.1 microns or less to a saponified ethylene-vinyl acetate copolymer. The present invention has been completed by not only being able to completely prevent the above-mentioned problems without any deterioration in the performance of adhesives, but also having the effect of further increasing workability when used as an adhesive compared to ordinary adhesives. . The saponified ethylene-vinyl acetate copolymer used in the resin adhesive composition of the present invention has a vinyl acetate content of 20 to 35% by weight, a saponification degree of 80% or more, a melt index of 30 to 200 g/10 min, and a particle size range. 40～
A thickness of about 1000 microns is preferable. This saponified ethylene-vinyl acetate copolymer can be obtained by, for example, pulverizing the ethylene-vinyl acetate copolymer in advance and saponifying the powder in a lower alcohol medium such as methanol or ethanol under an alkali catalyst, or by saponifying the ethylene-vinyl acetate copolymer in a lower alcohol medium such as methanol or ethanol under an alkaline catalyst, or by saponifying the ethylene-vinyl acetate copolymer in advance and saponifying the powder in a lower alcohol medium such as methanol or ethanol under an alkali catalyst. The copolymer is dissolved in a solvent of It is easy to precipitate the particles, perform purification such as washing with water or alcohol, and then dry and sieve to make the particle size uniform, or perform wet sieving after the washing process to make the particle size uniform, and then dry it. Manufactured in The gamma alumina used in the present invention is produced by hydrolyzing a volatile compound containing aluminum, such as anhydrous aluminum chloride, in a high-temperature oxyhydrogen flame, and as a result has a gamma structure and a primary particle size. is extremely fine, approximately 0.02 microns. In order to obtain the resin adhesive composition of the present invention, gamma alumina can be added in any of the manufacturing steps of the saponified ethylene-vinyl acetate copolymer, and the purpose can be achieved by uniformly mixing it, but the saponification step,
When it is added in the washing step, some of the aluminum oxide is lost in the separate lower alcohol, so it is preferable to add it in the step before or after drying as much as possible. Further, when saponifying the ethylene-vinyl acetate copolymer by dissolving it in toluene or xylene, it is preferable to add the alcohol after the step of precipitating the particles of the saponified product. The amount of γ alumina added is 0.005 to 1.0% by weight based on the saponified ethylene-vinyl acetate copolymer.
If the amount is less than 0.005% by weight, the effect of the present invention will not be observed, and if it is more than 1.0% by weight, the antistatic effect and powder flowability will be sufficiently improved, but the adhesive strength will decrease when used as an adhesive. Also, as seen in the examples, even if the same alumina is used, α
Even when alumina was used in the same manner as γ alumina, no effect was observed. It goes without saying that the resin adhesive composition of the present invention produced in this way can be used without impairing the original adhesive performance of the saponified ethylene-vinyl acetate copolymer, but the saponified particles are Because all particles, regardless of size, are separated into individual particles, particles of each particle size can easily and quickly pass through each sieve during the manufacturing process, making it possible to uniformize the particle size distribution of the product. Furthermore, when using products sieved into various particle size distributions, for example, for bonding woven fabrics, the adhesive particles can flow extremely smoothly from the adhesive feeder.
It has become possible to evenly spread adhesive powder on the woven fabric surface, completely eliminating problems such as adhesive particles aggregating on the woven fabric and causing uneven distribution, or failure to supply from the feeder. Not only has this problem been overcome, but it has also become possible to significantly increase the speed at which adhesive particles are distributed from the feeder, and the processing productivity of woven fabrics has been greatly improved. The effect of the resin adhesive composition of the present invention is that the ultrafine particles of γ aluminum oxide used in the present invention are
Its properties are different from other ordinary aluminum oxides,
It is said to have an electrically positive charge, and it is presumed that this positive charge has the effect of completely neutralizing the negative charge caused by friction between resins electrostatically and preventing the resin particles from aggregating together. be done. Next, examples of the present invention will be shown. Example 1 Vinyl acetate content 30% by weight, melt index
The saponified ethylene-vinyl acetate copolymer powder obtained by saponifying 100g/10 minutes of ethylene-vinyl acetate copolymer powder to a saponification rate of approximately 95% was divided into two parts, one of which was used as sample A to which nothing was added, and the other. Added 0.1% by weight of aluminum oxide C (product of Nippon Aerosil Co., Ltd., gamma alumina, primary particle size 5-20 mm), mixed thoroughly to prepare sample B, and sieved samples A and B under the same conditions. The properties were tested and the results shown in Table 1 were obtained. After the passability test in Table 1, the samples in each layer were observed using a microscope. As a result, sample A, that is, the product without alumina additives, showed that the saponified ethylene-vinyl acetate copolymer particles were clustered together in each sieve mesh. On the contrary, in sample B, each particle was observed to be separated separately.
Therefore, although Samples A and B have the same particle size distribution, Sample A without alumina has a particle size distribution on the larger side, giving an incorrect particle size distribution result.
【表】
試料ＡおよびＢのそれぞれ100メツシユオンサ
ンプルを150×200mmの60番綿ブロード面に25ｇ/
m2の割合に撒布し、同型の綿ブロードを重ねて
160℃、4.5Kg/cm2、10秒でホツトプレスし、次い
で引張り速度200mm/minで剥離して剥離強度を測
定した結果、試料Ａのものは1085ｇ／25mm、試料
Ｂのものが1065ｇ／25mmで接着強度として差がな
かつた。
実施例 ２
実施例１と同じエチレン−酢酸ビニル共重合体
けん化物に高純度アルミナAKP−20（住友化学
工業株式会社製αアルミナ、粒径0.3ミクロン）
とアルミニウムオキサイドＣとをそれぞれ表２に
示す重量比率で添加、混合し、各試料の粉体の流
れ性を測定した結果を表２に示した。
流れ性試験はガラス製円錐型ジヨーゴ（上径66
mm、下径９mm、傾斜角23゜）を上径を上に向けて
下の口を指で押さえ、これに試料70ｇを入れて下
の入口の指をはなし試料が流れ出る時間を測定し
て示した。
表２の結果からわかるようにエチレン−酢酸ビ
ニル共重合体けん化物に粒径0.3ミクロンのαア
ルミナを添加しても流れ性は解消されないが、粒
径0.02ミクロンのγアルミナを添加したものは流
れ時間が速く粉末流動性がきわめて改善されてい
る。[Table] 100 mesh samples of each of Samples A and B were placed on a 150 x 200 mm No. 60 cotton broad surface at 25 g/g.
Spread at a ratio of m 2 and overlap with cotton broadcloth of the same type.
As a result of hot pressing at 160℃, 4.5Kg/cm 2 for 10 seconds, and then peeling at a tensile speed of 200mm/min, the peel strength was measured. There was no difference in adhesive strength. Example 2 High purity alumina AKP-20 (α alumina manufactured by Sumitomo Chemical Co., Ltd., particle size 0.3 microns) was added to the same saponified ethylene-vinyl acetate copolymer as in Example 1.
and aluminum oxide C were added and mixed in the weight ratios shown in Table 2, and the flowability of the powder of each sample was measured. Table 2 shows the results. The flowability test was carried out using a glass conical diagonal (upper diameter 66 mm).
mm, lower diameter 9mm, inclination angle 23°) with the upper diameter facing up, hold the bottom opening with your finger, put 70g of sample into it, remove your finger from the bottom entrance, and measure the time it takes for the sample to flow out. Ta. As can be seen from the results in Table 2, adding α-alumina with a particle size of 0.3 microns to the saponified ethylene-vinyl acetate copolymer does not eliminate the flowability, but the addition of γ-alumina with a particle size of 0.02 microns does not improve flowability. The time is fast and the powder flowability is greatly improved.
【表】
またアルミニウムオキサイドＣの各添加率の各
試料について実施例１同様に綿ブロードの接着、
剥離試験して剥離強度を求めた結果を表２に示し
た。この結果、前記各試料の流れ性をも考慮すれ
ば、γアルミナでも0.005重量％以上の添加では
殆んど影響がなく、1.0重量％以上の添加では樹
脂粉末の流れ性は良いが接着剤が著しく低下する
ことがわかる。[Table] Also, for each sample with each addition rate of aluminum oxide C, adhesion of cotton broadcloth as in Example 1,
Table 2 shows the results of the peel test and the peel strength. As a result, if we also take into account the flowability of each of the samples mentioned above, we found that even with gamma alumina, addition of 0.005% by weight or more has almost no effect, and addition of 1.0% by weight or more improves the flowability of the resin powder, but the adhesive It can be seen that this decreases significantly.