JPS6131482A - Bonding method - Google Patents

Abstract

PURPOSE:To provide an adhesive containing microcapsules having specific relationship between the particle diameter of the capsule and the properties of the adhesive, having long pot life and high adhesion stability, suitable for dry lamination process, and capable of firmly bonding almost all kinds of materials. CONSTITUTION:An adhesive (preferably a urethane-based adhesive) containing microcapsules (having a maximum particle dimension of gammamax, average diameter of (m) and standard deviation of sigma) having a crosslinking and curing catalyst (preferably dibutyltin laurate) as a core, is applied to the surface of an adherend at a specific application pressure (A), and dried to form a dried coating film having an average thickness of (t). The other adherend is pressed to the adhesive film under a pressure (B) to effect the bonding of the adherends. The bonding process is carried out under the following conditions: t<=gammamax; 1/10m<= t<=m+3sigma, and 2/5m<=t<=m. Preferably, m is about 1-20mum, the application pressure (A) is lower than the critical pressure to break the microcapsule, and the pressure (B) is higher than the critical pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of Le Industry) The present invention relates to an adhesion method using an adhesive containing microcapsules, and in particular, to a curing reaction type adhesive using a catalyst as a core material. The present invention aims to provide an adhesion method that enables good adhesion by mixing microcapsules, and particularly relates to an adhesion method suitable for dry lamination.

(Prior art) The dry lamination method is a method in which a solvent-based adhesive is applied to a material to be bonded, such as one film, and after drying, it is laminated to a material to be bonded, such as the other film. Since it can be applied to almost all materials, combinations of materials can be freely selected, processing speed is fast, and adhesive strength is stable, so it is widely used, especially in the field of packaging materials.

(Problems to be Solved by the Invention) However, in recent years, in the field of packaging materials, there has been a trend toward high-mix, low-volume production and short delivery times, and it is desired to improve processing speed and shorten adhesion stabilization time.

The dry lamination method is certainly fast in processing speed, but since its curing mechanism is a crosslinking reaction using a chemical reaction, it requires a lot of time to stabilize the adhesion. Especially recently, the number of such jobs is increasing. In addition, since it takes time to stabilize the adhesive, there is a delay in checking the adhesive strength, and if a problem such as insufficient adhesive strength occurs, once it is discovered, it cannot be taken back due to delivery deadlines and workers This was a serious concern. In order to shorten this adhesive force stabilization time, so-called aging time, the curing mechanism of the adhesive is a crosslinking reaction using a chemical reaction, so methods of increasing the temperature and using a catalyst can be considered. Regarding the temperature, there is a problem with the post-processing of the bonded materials, so the temperature was 45℃.
There are upper limits before and after. Within this limit, adhesion stabilization requires
Since the process requires a long time of 70 to 250 hours, the catalyst is considered to have an accelerating effect.

However, the use of catalysts has always been accompanied by problems with the pot life of the adhesive, making their use difficult.

Therefore, the present inventor previously developed an adhesive method in which a catalyst is microencapsulated as a core material and the microcapsules are mixed into an adhesive. According to this method, curing during adhesion can be promoted without affecting the pot life of the adhesive. However, in the second method, its ability was not necessarily sufficient when compared with the promoting effect that could be considered based on the estimated amount of catalyst. Therefore, we worked hard to find out the cause, and found that the cause was the low destruction rate of microcapsules. In order to increase the fracture rate, it is possible to increase the fracture pressure, that is, the nip pressure during dry lamination, but simply increasing the nip pressure will cause new appearance problems such as wrinkles in the laminate, so this is not a sufficient solution. It is not.

(Means for Solving the Problems) Therefore, in view of the above problems, the inventors of the present invention have made various intensive studies and determined that the relationship between the amount of adhesive applied and the particle size of the microcapsules is a specific relationship. The present invention was completed based on the finding that the above-mentioned drawbacks of the prior art can be sufficiently solved.

That is, the present invention applies an adhesive containing microcapsules (maximum particle size γ■aX, average particle size m, standard deviation σ) containing a crosslinked curing catalyst as a core material to a surface to be adhered at a predetermined application pressure (A ) and drying to form a dry film with an average thickness of 1), and then press-bonding another adherend material with a predetermined pressure (B).
This bonding method is characterized in that the relationship between and t is t≦γpengaX.

Next, to explain the present invention in more detail, the adhesive used in the method of the present invention is a solution type or a solvent-free type adhesive, and these adhesives themselves are all known.
Examples include polyurethane-based, acrylic-based, and epoxy-based adhesives, particularly cross-linked polyurethane-based adhesives prepared by dissolving polyhydric alcohols such as polyester polyol, and tolylene diisocyanate and other polyisocyanates in an appropriate solvent. Curable adhesives are preferred.

All such adhesives are readily available on the market, and any conventionally known adhesives can be used in the present invention.

In such adhesives, the reaction of the curing component, such as the reaction between a polyol and a polyisocyanate, proceeds gradually during storage, resulting in problems with the pot life of the adhesive.

As mentioned above, the present inventor previously adopted a microencapsulated catalyst as the catalyst to be added in order to solve such pot life problems, but the present invention further improves this method. , provides an adhesive method that provides excellent adhesive performance.

The main features of a preferred embodiment of the method of the present invention are: (1) adding a microencapsulated catalyst to a conventional cross-linked curing adhesive; (2) setting the maximum particle size of the microcapsules to about IBm;
~ about 100 gm, preferably about IILm ~ about 2o1
(3) When applying the adhesive containing the above catalyst to the adhered material and drying it to form a dry film, the average thickness of the dry film (1) should be determined by the maximum particle size of the microcapsules. (4) The relationship between the average thickness of the dry film (t), the average particle diameter of the microcapsules (m), and its standard deviation (σ) , l/10+w≦t≦m+3 cr, most preferably 2
15 m≦t≦m.

By having the method of the present invention as described above, when applying a cross-linked curing adhesive to a material to be bonded, since the adhesive usually consists of a large amount of solvent, the microcapsules in the adhesive are is hardly destroyed by the coating pressure (A) of ordinary application means, and when the solvent is removed and a dry film is formed, the maximum diameter (γmax) of the microcapsules in this film is Thickness 1)
Since the size of the microcapsules becomes larger, the microcapsules are destroyed by first pressing another adherend material onto the surface of the microcapsules at a predetermined pressure (B), and only then do they exhibit a catalytic effect. Therefore, since the catalyst does not act before use, the adhesive has excellent pot-ripe and can exhibit excellent adhesion ability before use.

In a more desirable embodiment, the thickness (t) of the dry film,
The relationship between the average particle diameter (m) of the microcapsules and its standard deviation (σ) is such that 1/lOm≦t≦m + 3σ, most preferably 215≦t≦m.

By adopting such a structure, the microcapsules in the adhesive are not substantially destroyed by the coating pressure during application of the adhesive, and the average particle size of the microcapsules in the film after drying is equal to that of the average film. Since it is larger than the thickness, by pressing another material to the surface,
Most of the microcapsules are destroyed by the pressure (B), and as a result, sufficient catalytic action is obtained and excellent adhesive ability is exhibited.

Therefore, the wall material of the microcapsule in the preferred embodiment described above needs to be durable against solvents in adhesives, such as ethyl acetate, isopropanol, methyl ethyl ketone, and the like. Preferred wall materials for such microcapsules include polyamide, polyurethane, polyester, polyurea, epoxy resin, or crosslinked products thereof, and any other material that is not soaked by the solvent in the adhesive may be used.

The catalyst encapsulated in the microcapsules may be any compound as long as it has the function of crosslinking and curing the adhesive. For example, for polyurethane adhesives often used in dry lamination methods, The method for producing microcapsules, in which dibutyltin dilaurate is particularly preferred, has already been almost established, and includes an interfacial polymerization method, 1n
There are in-situ polymerization methods, phase separation methods from aqueous and organic solvent systems, in-liquid drying methods, melt-dispersion cooling methods, in-liquid curing coating methods, etc. Since the microcapsules used in the present invention are required to have solvent resistance, , interfacial polymerization method, in + in situ polymerization method, polymerization type of in-liquid curing coating method, and melt dispersion cooling method are preferable, but phase separation method and in-liquid drying method can also be used by selecting the wall material depending on the solvent that requires resistance. It is possible.

The particle size of the microcapsules used in the present invention is important, and in the present invention, in general, from the viewpoint of the adhesion rate to the adhered material, the destruction rate during adhesion, the thickness of the adhesive film, etc. If the average particle size is about 1JJ, ~1001L, preferably about 1#L~20#L, the breakability during adhesion is good, but the adhesive material If the adhesion rate is too low, there will be a problem that sufficient destructibility will not be obtained during pressure bonding.

In the present invention, as a result of various studies on the relationship between the adhesion rate and the destruction rate in relation to the dry film of the adhesive, we found that the maximum diameter (γwam), average particle size (m), and standard deviation of the microcapsules The relationship between (σ) and film thickness 1) is, first of all, t≦γ−a! By using this method, larger capsules in the particle size distribution of microcapsules are reliably destroyed, which is superior to the conventional technology.
Next, it was found that the relationship of 1/10■≦t≦m+3σ shows sufficient action and effect, and furthermore, the highest action and effect can be obtained when 215■≦t≦m. That is, when t becomes thinner than 215 m, the adhesion rate of the microcapsules to the adhered material decreases, the leveling property of the dried film decreases, and the adhesive performance becomes insufficient. On the other hand, if t far exceeds the value of m, the destruction rate of microcapsules during compression will be significantly reduced. Therefore, if the microcapsules have a uniform particle size within a range that poses no problems in use,
The adhesion of the microcapsules to the material to be adhered can be improved by reducing the thickness of the dry film (1) to the average particle diameter of the microcapsules plus three times the standard thickness, preferably to the average particle diameter (m) or less. It has been discovered that it is possible to simultaneously achieve sufficient efficiency and destruction rate.

The amount of microcapsules added to the adhesive can be adjusted to the desired curing time, but there are limitations due to the effectiveness and cost of using it as a catalyst, and usually the resin content of the adhesive is limited. 10% by weight or less, preferably about 0. The amount corresponds to i~1.0% by weight.

The characteristics of the method of the present invention have been mainly explained above, but for the reasons mentioned above, the method of the present invention is particularly suitable for applying a solution-type, cross-linking and curing adhesive to a material to be adhered, such as the dry lamination adhesive method. This method is most suitable for bonding, drying, overlapping other materials to be bonded, and bonding by continuously pressing with a pressure roller, etc. However, it is not limited to the dry lamination method, and other bonding methods that use a similar mechanism are also suitable. All methods are applicable.

Therefore, the adhesive itself is limited to urethane adhesives, and the catalyst is not limited to dibutyltin dilaurate, but any other adhesive or catalyst may be used as long as it adheres by the same mechanism.

Next, to explain the process of the method of the present invention, such a process itself may be a conventionally known process, but for example, an adhesive containing microcapsules as described above may be applied to any of the adhered materials. Coat one or both and dry to form a dry film. The coating method may be, for example, gravure coating, roll coating, kiss coating, or any other method. However, due to coating pressure such as nip pressure during coating,
The coating pressure or the particle size or wall thickness of the microcapsules must be appropriately selected so that the microcapsules are not substantially destroyed.

Next, by overlapping the materials to be adhered and pressing them together, the pressure at that time substantially destroys the microcapsules, a catalytic action is developed, and good crosslinking and curing occurs to achieve sufficient bonding. Therefore, the breaking strength of microcapsules is
The strength of the microcapsules and the coating pressure and pressure during crimping should be adjusted so that they can withstand the coating pressure during coating and are destroyed by the pressure during crimping.

After the bonding is completed, the method of the present invention is completed by winding up the bonded product, for example, on a roll.

(Function/Effect) According to the method of the present invention as described above, by adopting the above-described configuration, the pot life of the adhesive used is sufficient, and sufficient catalytic action is exerted during use.
Sufficient adhesion occurs, stable adhesion stability can be obtained, and the problems of the prior art described above are fully solved. Further, because of the above-described structure, the method of the present invention has an economical advantage in that superior bonding can be achieved compared to conventional methods without any modification of existing equipment and in the same process.

Next, preferred embodiments of the present invention will be specifically explained with reference to Examples. Note that % in the text is based on weight.

Example 1 Microcapsules containing dibutyltin dilaurate encapsulated in a polyurea shell in a urethane adhesive (solid content 25%) [catalyst amount/shell material 2 times ■] with a solid content of 0. It was added in an amount equivalent to 0.5 Oz, and applied to the surface of the synthetic resin film with a nip pressure (linear pressure) of 2 kg/m so that the average dry thickness was 4. The synthetic resin film was continuously crimped with a nip pressure (linear pressure) of 7 kg, and the adhesive strength (ON/CPP) of the resulting laminate was determined.
= 850g/15 layers■, 0.5$=880g/15
It was m■. Further, when the reduction of incyanate in the film, which is the effect of accelerating the hardening of the adhesive by using a catalyst, was investigated, and the results were as shown in Fig. 1.

Example 2 The thickness of the dried film in Example 1. 10=m, 5le ■
Adhesion was carried out in the same manner as in Example 1, except that 3IL and 3IL■ were used, and the curing speed was examined from the decrease in isocyanate, as shown in FIG. However, the blank had no catalyst added, and the coating time was 4 m).

[Brief explanation of the drawing]

FIG. 1 shows the effect of accelerating the curing of an adhesive by using a catalyst, and FIG. 2 shows the relationship between the thickness of the adhesive layer and the curing rate.

Claims (7)

[Claims] (1) Microcapsules with a crosslinked curing catalyst as the core material (
An adhesive containing maximum particle size γmax, average particle size m, standard deviation σ) is applied to the surface to be bonded at a predetermined application pressure (A) and dried to form a dry film with an average thickness (t). In the bonding method that consists of then pressing another bonded material at a predetermined pressure (B), the relationship between γmax and t is expressed as follows:
An adhesion method characterized in that t≦γmax. (2) The relationship between m, σ and t is 1/10m≦t≦m+
The bonding method according to claim (1), wherein the bonding temperature is 3σ. (3) The bonding method according to claim (1), wherein the relationship between m and t is 2/5m≦t≦m. (4) The bonding method according to claim (1), wherein m is about 1 μm to about 100 μm. (5) The bonding method according to claim (1), wherein m is about 1 μm to about 20 μm. (6) The adhesive according to claim (1), wherein the application pressure (A) is a pressure that does not destroy the microcapsules, and the pressure during pressure bonding (B) is a pressure that destroys the microcapsules. Method. (7) The adhesive is a one-component or two-component adhesive such as polyurethane, acrylic, or epoxy, and the curing catalyst is dibutyltin dilaurate (
Adhesion method described in section 1).