JPS61181870A - Reactive hot melt - Google Patents

Abstract

PURPOSE:To provide a reaction hot melt having excellent grab on an oil surface, consisting of an epoxy resin, a reactive diluent contg. an epoxy group, NBR having a medium and/or medium high nitrile content, a latent curing agent and an accelerator. CONSTITUTION:5-40pts.wt. reactive diluent (A) contg. an epoxy group (e.g. allyl glycidyl ether) having a viscosity of 5X10<3>cps or below at 25 deg.C, 5-50pts.wt. medium and/or medium high NBR (B) having a bonded acrylonitrile content of 25-30 and 31-35, 1-20pts.wt. latent curing agent and accelerator (C) (e.g. dicyandiamide) and optionally, additives such as inorg. filler, leveling agent, etc., are added to 100pts.wt. epoxy resin having EPW of 300-700g/eq. and a softening point of 60-130 deg.C to obtain a reactive hot melt having a viscosity of 10<8>cps or above at 20 deg.C and 10<5>cps or above at 100 deg.C, a reaction-initiating temp. of 150-190 deg.C and the lowest viscosity of 10<4>cps or above.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention can be applied to an oil-surface steel plate using a hot melt applicator, and is hard at room temperature.
Because there is almost no tack, it is easy to handle the coated panels, etc., and in the post-baking coating oven.
The present invention relates to a reactive hot melt that can be thermally cured through leveling as it melts to impart adhesion and sealing functions.

<Conventional technology and its problems> Traditionally, adhesion and sealing were performed separately using different materials.

For example, if a paste or liquid adhesive, or sometimes a sheet adhesive, is applied to the bonded area and then heat-cured in the baking oven in the post-process, it is necessary to seal off gas or liquid. After baking, a sealant is applied to the necessary areas and cured at a temperature lower than the baking temperature.

The reason why the sealant is cured at a low temperature is because the sealant contains vinyl chloride or chloroprene rubber, which decomposes at high temperatures.

If you want to use adhesive to perform sealing at the same time, you will need to use a sheet of adhesive of a certain width and thickness.

Another method is to insert it into the gap between the joints or between the joints.

Although it is possible to bond and seal at the same time with this method, it is difficult to apply to complex shapes, and even if it can be sealed, the finished product is wavy due to its high fluidity when heated. The disadvantage is that trimming is often necessary.

Several sealants have been proposed that do not contain vinyl chloride or proloprene and are applied and heat cured at the same time as adhesives, but these have the drawback of being tacky after application and making it difficult to handle panels, etc.

Similar to the present invention, there has been an attempt to reduce tack by heating the application, but the tack is large at room temperature and the oil surface fixation and adhesive strength are poor, so semi-curing by dielectric heating is performed before handling. It appears that they have overcome these problems.

<Objective of the Invention> The present invention is capable of hot-melt application to oil-surface steel plates, is removable, is easy to handle after application, and is heat-cured at around 160°C in a baking oven to achieve adhesion and sealing. The object of the present invention is to provide a reactive hot melt that can be used in the sheet metal industry, especially for seal processing and baking painting.

<Structure of the invention> The present invention is.

(L) Epoxy resin (EPW: 30Q ~?QO
g/eq.

Softening point BO ~ 110°C) 100 parts by weight (b) Epoxy group-containing reactive diluent 5 to 40 parts by weight (C) Medium and high nitrile NBR 5 to 50 parts by weight (d) Latent curing agent and accelerator 1 The present invention provides a reactive hot melt characterized by containing ~20 parts by weight as an essential component.

The reactive hot melt of the present invention will be explained in more detail below.

(a) Epoxy resin Ebibis type epoxy resin obtained by condensation of bisphenol A and epichlorohydrin, novolak type epoxy resin, elastomer-modified epoxy resin (eg, NO
R-modified epoxy resin)? i Single and/or mixture, EPW 250-700 g/eq, softening point 60-
A temperature within the range of 110° C. can be used.

To illustrate, Epicote 1O01 has an EPW of 450 to
500, has a softening point of 68°C, and is an Ebibis type resin, which corresponds to Epicote 1007 and Epicote 82.
A 35:65 (by weight) mixture of 8 has an EPW of approximately 26
0, the softening point is approximately 60°C.

This epoxy resin cures with heat and helps provide the necessary strength, and the epoxy resins listed here are
Even if it is solid at room temperature, its viscosity typically drops rapidly once it exceeds its softening point.

Although preferred for hot melt applications, it can lead to dripping and running during the curing process. Moreover, this epoxy resin alone,
Oil surface adhesion is difficult.

(b) Reactive diluent Reactive diluent containing epoxy group refers to monofunctional epoxy such as allyl glycidyl ether, phenyl glycidyl ether, and glycidyl methacrylate, gepoxy such as polyalkylene glycol, low viscosity alicyclic epoxy, neo The viscosity at 25°C of pentyl glycol diglycidyl ether, flexible side chain type epoxy resin, hydrogenated bisphenol A diglycidyl ether, etc. is 5 × 1.
03CPS or less.

Reactive diluents reduce the viscosity of epoxy formulations, so
A group of materials called reactive diluents have fluidity at room temperature, which is undesirable.

It is an essential component for oil surface adhesion because of its affinity for oil surfaces (the main reason is thought to be that its molecular weight and SP value are smaller than normal epoxy) and its strong ability to replace the surface of the adherend with oil. It is. The amount of low viscosity diluent required for oil surface adhesion is small, and the amount required increases with increasing viscosity, but although the minimum required amount of these reactive diluents varies by type, The hardness settles at approximately the same level, therefore, considering many types of diluents, 5 to 40 parts by weight is an applicable amount.

(c) Medium/medium/high nitrile NBR As is well known, general-purpose epoxy resins and NBR are highly compatible and are a preferred combination.

Even if they fall within the same NBR category, polymers with a high amount of bound acrylonitrile or higher than medium nitrile are preferable because they have higher compatibility, give a finer texture to the blend, and make the skin smoother.

However, high nitrile rubber has a high Mooney viscosity, making it difficult to mix, and the mixture is too stiff, causing problems such as die swell effects during hot melt application.

In the first place, the purpose of using NBR is to adjust the viscosity.

In other words, it is necessary to have a viscosity curve that is hard at room temperature, decreases to a viscosity that allows application at construction temperatures, and hardens without dripping, although it levels during the curing process. This is understandable because the combination of epoxy resin and reactive diluent is too soft and flows out during the curing process.

Suitable solutions vary depending on the type and amount of reactive diluent used and the Mooney viscosity of the NBR used, and in principle:
The more the reactive diluent is used, the more the reactive diluent is used. Although low molecular weight liquid NBR is not included, it is possible to use gently partially crosslinked NBR or semi-solid NBR with a moderate molecular weight.

Medium nitrile and medium high nitrile refer to those having a bound acrylonitrile content of 25 to 30 and 31 to 35, respectively.

(d)? Latent curing agents and accelerators Latent curing agents and curing accelerators are used because they are stable to a certain extent not only at room temperature but also at workable temperatures and rapidly cured at curing temperatures. The rate of solidification reaction is controlled by using dicyandiamide, BF3 amine complex, aromatic diamine, imidazole compound, urea compound, etc. alone or in appropriate combinations. The optimum blending amount varies depending on the type of curing agent, but can be found in the range of 1 to 20 parts by weight.

The composition consisting of the four essential components mentioned above may be used as is, but in order to reduce the cost as much as possible, inorganic fillers may be added, coloring agents, anti-sagging agents, etc.
Add leveling agent, etc. If significant amounts of inorganic fillers are added, slightly more reactive diluent must be used to prevent the formulation from becoming too stiff.

The reactive hot melt of the present invention containing the essential components (a) to (d) in a specific range must be adjusted to satisfy the following conditions.

1) Toacps or higher at 20°C. First of all, this condition is that the adhesiveness is very low, which is of great significance in preventing adhesion when manually transporting a workpiece that has been coated and has not yet been cured. Secondly, if it takes a long time for the coated workpiece to enter the curing oven, it prevents the workpiece from changing its shape at the time of coating due to its own weight.

1i) 105CPS or less at 100°C.

This condition is essential for application to be possible with current hot melt applicators.

1ii) The reaction start-up temperature is 150° C. or higher and 190° C. or lower, and the minimum viscosity is 104 CPS or higher. These conditions are necessary so that the paints are cured simultaneously in the baking oven and are leveled during the curing process but do not drip.

It is not so difficult to achieve i), ii), and 1ii) alone, but in order to satisfy all of them, it is necessary to select and combine the quantity and quality of essential ingredients, adjust with additives other than essential ingredients, or One is necessary.

In order to achieve both i) and ii), the effect of essential component (a) is large, that is, the extreme viscosity change below the softening point and above the softening point of essential component (a) greatly contributes to the compatibility of i) and ii). However, the addition of essential component (b) considerably reduces its effectiveness. If there is some problem in achieving both i) and ii), it can be solved by reducing the essential component (b) to the extent possible or by narrowing the molecular weight distribution of the essential component (a). Furthermore, if the overall viscosity is low, adding an inorganic filler will increase the average viscosity.

To achieve 1ii) with L that is compatible with 1) and ■).

An essential component (d) such as a latent curing agent is selected to adjust the rise temperature, and then an essential component (c) is added to prevent a rapid drop in viscosity. Addition of essential component (c) is l),
It has a great effect of reducing the rate of viscosity reduction at temperatures above the temperature suitable for construction, without having much of a negative effect on

Viscosity 1'; J! ! Regarding adjustment, essential components (b) and (c)
They are contradictory: increasing one will increase the other, but if you go to extremes, 1) may be compromised. In such a case, it is also possible to adjust by adding an inorganic filler as described above.

In this way, books that satisfy predetermined viscosity characteristics, etc. (conditions i) to 1ii)) by appropriately combining the quantity and quality of the essential ingredients, or by adding compounding materials other than the essential ingredients. The reactive hot melt of the invention can be applied to oil-surfaced steel plates with a hot melt applicator for 1 hour, and there is no stickiness or flow at room temperature, and leveling and hardening occur in succession during baking painting, resulting in a beautiful appearance and excellent gap-spacing. It is possible to achieve sealing, strong adhesion, etc.

Example of implementation Next, the present invention will be specifically explained using examples.

Table 1 The formulation of Example I is listed in Table 1 of Example I. The components up to the fourth stage are essential components, and the last stage is non-essential components. These can be mixed in a conventional manner using a roll. And here, in addition to the essential ingredients, inorganic fillers are used in NB.
In addition to helping to improve the dispersion of R, the purpose is to reduce the cost of the formulation and slightly increase the viscosity over the entire temperature range. 15i instead of 25 parts by weight
This is possible by reducing it to i parts. Therefore, although the inorganic filler cannot be said to be an essential component, it is a compounding agent that is preferably used, as in the case of general adhesive compositions.

Figure 1 shows the viscosity curve of Example I and three conditions (i)
The figure shows that ~1ii)) is satisfied, point A is the viscosity at 20 °C, satisfies i), point B is the viscosity at 100 °C, satisfies Ii), and point 0 is the rise. and the viscosity at that temperature, which satisfies 1ii).

This formulation is 1% per hour at 60°C.

At 100°C, the viscosity increases by 100%, ensuring thermal stability during construction. The reactive hot melt 2 is applied with an applicator 1 as shown in FIG. 2 through a nozzle 3 onto an oil surface steel plate 4 coated with antirust oil using compressed air as shown in FIG. 3. construction, and the fourth
It was fixed at the position shown in the figure and cured. Figure 4a shows
An example tilted by 30 degrees, Figure 4b is a horizontal example, and Figure 4C is a 30 degree tilted example.
@Tilt example, Figure 4b is a vertical example.

The upper row shows the results immediately after hot melt construction, and the middle and lower rows show the construction results of Example 1 and Comparative Example I, respectively.

As a result, it can be seen that the samples of the examples achieve smooth and effective sealing no matter what spatial arrangement they are applied to. Furthermore, Table 1-2 shows the adhesive strength when this compound was cured and cured under the same conditions, and it can be seen that it has sufficient adhesive strength as well as sealing.

(Comparative Example Work) The mixture obtained by removing only the NBR component from the formulation of the Example Work has adhesive strength as shown in Table 2, but has a viscosity curve as shown in Figure 5. Therefore, it is undesirable because it is sticky at room temperature, and although it is easy to apply, it is undesirable because it drips and flows when applied in a specified spatial arrangement as shown in the lower part of Figures 4a to 4d. .

Table 2 Adhesive Strength However, the adhesive strength was measured at room temperature after 12.5 layers of oil-faced steel plates were laminated together and cured at 160° C. for 30 minutes.

(Comparative example ■) In the formulation of the example process, the reactive diluent was eliminated and NB
A formulation with 5 parts of R instead of 15 parts has a viscosity condition of i
), ii), and 1ii) were satisfied, but the adhesive strength to the oil-surfaced steel plate was completely inferior and unusable. However, since the viscosity condition is satisfied, effective sealing is achieved in any spatial arrangement, as in Example I.

Table 3 summarizes the formulations, characteristics, defects, etc. of the examples and comparative examples, including the examples described so far. The viscosity curves and sealing states in various spatial arrangements are the same as those already illustrated, so they will be briefly described.

The epoxy used in Example ① is a 35:65 (weight ratio) of epoxy that is solid at room temperature and epoxy that is liquid at room temperature.
It is a blend of Epicote ■l 007 mentioned earlier.
and Epicote ■828.

Based on Table 3, Examples and Comparative Examples will be explained while excluding overlapping parts.

In Example No. 1, the formulation is based on the most commonly used epoxy resin, and the performance is at a standard level (among all Examples). The medium-high nitrile used has a low Mooney viscosity and mixes well with epoxy, making it easy to mix.

In Example No. 2, the epoxy resin is a blend, so it is flexible, and the diluent has a very low viscosity, so the amount used is smaller than in Example No. 091. The rubber has a Mooney viscosity. It's medium-sized, so I don't need much. High adhesive strength, ie, high peeling performance.

Examples No. 3 and 3 have high heat resistance because they use novolac epoxy.

Examples No. 4 contains less filler, more rubber and reactive diluent, and the cured product is soft, making it suitable for cases where softness is more important than adhesive strength.

In Example No. 5, the rubber of Comparative Example No. 3 was made to have a low moony and the viscosity was lowered to a level where hot melt application was possible, so as to satisfy the viscosity conditions.

Examples No. 8 and 8 partially use epoxy modified with NBR having a carboxyl group as the epoxy resin, and have improved performance (impact resistance, flexibility, adhesion) compared to Example No. 1. power), but costs are also rising.

As explained above, according to the reactive hot melt of the present invention, it is not only possible to apply hot melt to the joints of oil-faced steel plates, but it is also easy to handle because it is less sticky at room temperature. Even when applied to any spatial arrangement, it is possible to achieve clean sealing and adhesion after baking painting.

[Brief explanation of drawings]

FIG. 1 is a graph showing a viscosity curve of a hot melt produced in an example of the present invention. FIG. 2 is a schematic side view of the hot melt applicator used in Examples and Comparative Examples. Fig. 3a is a perspective view showing a state in which hot melt is applied to an oil-surface steel plate, and Fig. 3b is an end view of Fig. 3a. Figures 4a, 4b, 4c and 4d show various spatial arrangements for true melt application, the upper row being immediately after application;
The middle row shows the hot melt construction results of the example construction, and the lower row shows the hot melt construction results of Comparative Example 1. FIG. 5 is a graph showing the viscosity curve of the hot melt of Comparative Example I. Explanation of symbols■...Hot melt applicator, 2...Hot melt, 3...Nozzle, 4...Oil surface steel plate, 5
...Hot melt FIG, 2 FIG, 4a FIG, 4
bFIG, 4cFIG・4dFI
G, 5 TEMP DEG (c) Senshi Urine City Official Book (Method) % Formula % 2. Name of the invention Reactive Hot Melt 3. Person making the amendment 41 (Relationship with the case Patent applicant Location: Minato-ku, Tokyo Shinbashi 5-36-11 Name (671) Yokohama Rubber Co., Ltd. 4, Agent Address: 101
Phone: 864-4498 Address: 3-2-2 Iwamoto-cho, Chiyoda-ku, Tokyo May 28, 1985 (Shipping date) 6. Subject to amendment

Claims (1)

[Claims] (a) 100 parts by weight of epoxy resin (EPW: 300-7
(b) 5 to 40 parts by weight of reactive diluent containing epoxy groups (c) 5 to 50 parts by weight of medium and/or medium-high nitrile NBR (d) Latent hardener and accelerator A reactive hot melt characterized by containing 1 to 20 parts by weight of a reagent as an essential component.