JP2000096026A - Mastic sealer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a mastic sealer having a viscosity capable of coating a sealer without heating and forming a cured membrane capable of enduring washing shower after its coating by adding a specific cured membrane forming component to a specific solvent-free and one-pack liquid type mastic sealer. SOLUTION: This mastic sealer is obtained by adding (F) a cured membrane forming component consisting of a polyisocyanate to a solvent-free and one-pack liquid type mastic sealer consisting of (A) a vinyl chloride resin and (B) a liquid state synthetic rubber, both of which viscosities are adjusted by (C) a plasticizer and (D) a filler, and added with (E) an adhering capacity-imparting agent consisting of a thermosetting resin. As the component E, a liquid state amine- curing type epoxy resin is preferably used. In the case that the component F is a pre-polymer, the pre-polymer is preferably a product obtained by reacting a liquid state polybutadiene having terminal OH with a diisocyanate compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile hood (hood), trunk lid,
The present invention relates to a sealer having elasticity, that is, a mastic sealer (also referred to as a mastic adhesive) used as an adhesive and cushioning material between an outer panel such as a door and a roof and an inner panel.

Here, a case where the present invention is applied to a bonnet sheet will be described as an example, but the mastic sealer of the present invention can be applied to other parts.

[0003]

2. Description of the Related Art An example in which a general mastic sealer (hereinafter sometimes simply referred to as "sealer") is applied to a bonnet B will be described (see FIGS. 1 and 2).

[0004] The mastic sealer is used to form an adhesive / buffer layer (sealant layer) 12 at the center of the outer panel 14 and the inner panel 16 by being interspersed in a spot-like manner. That is, the bonnet B, which is an outer panel 14 / inner panel 16 assembly, is applied in a dumpling shape having a diameter of 2 to 3 cm at a plurality of predetermined positions on the center of the outer panel 14 and then the inner panel 16 is overlaid. The outer edge of the outer panel 14 is hemmed 14a to the inside of the back to assemble and integrate. The gap between the outer panel 14 and the inner panel 16 in the hemmed portion 14a is not shown,
Usually sealed with an epoxy sealant. Reference numeral 18 in the drawing is a punched hole for reducing the weight.

As shown in FIG. 3, the bonnet B is subjected to showering (washing) with water or hot water, acid washing, alkali washing, etc., as a pretreatment for electrodeposition coating.
During this time, the mastic sealer is heated and cured by the heat of the electrodeposition curing furnace to form the sealant layer 12.

Conventionally, a solvent type mastic sealer has been used as the mastic sealer. The reason is that the solvent evaporates while the member is being conveyed in the cleaning process after applying the sealer, and a hardened film is formed on the surface of the sealer.

However, there is a problem that the working environment in the sealer coating process is deteriorated due to volatilization of a solvent such as toluene contained in the sealer.

Particularly, recently, VOC (Volatile Organic C)
ompound) Due to increasing regulations, the use of solvent-type mastic sealers is likely to be prohibited or restricted.

Therefore, as a solventless mastic sealer in which the solvent of the solvent type mastic sealer is replaced with a non-volatile solvent such as a plasticizer, for example, those having the compositions shown in the conventional examples in Table 1 have been used.

That is, the solventless mastic sealer is P
VC, liquid synthetic rubber (liquid NBR), plasticizer, filler,
This is a one-pack paster containing a liquid epoxy resin and an epoxy curing agent as an adhesion-imparting agent. In this sealer, PVC is fused in a high-temperature atmosphere of about 180 ° C. to form a matrix of the sealer, and the adhesion to the steel sheet is enhanced by a curing reaction of the epoxy resin.

[0011] The need to set the curing temperature to a relatively high temperature of 180 ° C is because the mastic sealer is made into one liquid.
This is because room temperature solid dicyandiamide (melting point: 214 ° C.) is used as an epoxy curing agent. Atmospheric temperature is 18
Even at 0 ° C., it is presumed that the temperature inside reaches a temperature near the melting point, and further, the heat is stored by a curing reaction (exothermic reaction) and exceeds the melting point.

[0012]

However, in the sealer having the above-mentioned structure, since a cured film is not formed on the surface of the sealant layer after application, there is a problem that the sealer is scattered, dropped, deformed, etc. by a washing shower.

As a countermeasure, a mastic sealer has been proposed in which the viscosity of the sealer is increased so as to be able to withstand a shower (see Japanese Patent Application Laid-Open No. 62-146973).

However, the sealer has a high viscosity and therefore has poor dischargeability, and it is necessary to heat the piping system of the coating equipment.

Further, from the viewpoint of energy saving, the baking temperature of the electrodeposition curing furnace for curing the mastic sealer is 18
Although there is a demand to lower the temperature from 0 ° C. to 150 ° C. or less, the current mastic sealer has a problem that when the temperature is 150 ° C. or less, the adhesive strength of the heat-cured sealant layer to the panel rapidly decreases.

The reason why the adhesive strength is lowered is that a high-melting-point (more than 200 ° C.) latent curing agent such as solid dicyandiamide which is a curing agent for an epoxy resin blended in a conventional mastic sealer does not melt. This is presumed to be because no adhesive strength is exhibited.

It is conceivable that a curing reaction of the epoxy resin is caused by using a catalyst in a heating atmosphere at 150 ° C., but there is no suitable catalyst at present. In order to solve this problem, it is conceivable to use a solid amine or a liquid amine having a melting point of about 100 ° C. However, if the solid amine having a melting point of about 100 ° C. is mixed with the epoxy resin, the curing reaction is gradually performed. It was found that the viscosity increased and the coating became difficult.

That is, there is a problem that it is difficult to obtain a solventless one-pack type sealer having a long pot life (usable life) (usually 700 hours or more). In particular, in summer or the like, the atmospheric temperature of the storage room increases, and the pot life is further shortened.

In view of the above, the present invention provides a solventless, one-pack type mastic sealer that has a viscosity that can be applied to a sealer without heating and that can form a cured film that can withstand a washing shower after application. The purpose is to do.

Another object of the present invention is to provide a solventless one-pack type mastic sealer capable of exhibiting sufficient adhesive strength to a panel even at a heat treatment temperature of 150 ° C. or less.

[0021]

A mastic sealer according to the present invention solves the above-mentioned problems by the following constitution.

One aspect of the present invention is a solvent-free one obtained by adjusting the viscosity of a vinyl chloride resin and a liquid synthetic rubber with a plasticizer and a filler, and further adding a heat-curable epoxy resin as an adhesion-imparting agent. A liquid mastic sealer is characterized in that polyisocyanate is added as a cured film forming component.

As the thermosetting resin, a liquid amine-curable epoxy resin is generally preferable because of its excellent adhesiveness to a steel sheet.

When the polyisocyanate is a prepolymer, it is desirable from the viewpoint of water resistance that the prepolymer is a reaction product of a liquid polybutadiene having a terminal OH and a diisocyanate compound.

In another aspect of the present invention, the viscosity of a vinyl chloride resin and a liquid synthetic rubber is adjusted with a plasticizer and a filler, and an epoxy resin, which is a thermosetting resin, is added as an adhesion-imparting agent. And a secondary amino group (imino group) prepared by reacting an epoxy resin with a primary amine so that the primary amino group disappears. Body and
It is characterized in that polyisocyanate is added as a cured film forming component.

The primary amine is preferably a 2-phenyl-1-imidazoline derivative. It is a monoamine and easily loses primary amino groups.
Even if some unreacted amine remains, the melting reaction of the unreacted amine is about 100 ° C., which is higher than room temperature, so that the curing reaction at room temperature does not proceed so much, and the pot life is shortened due to an increase in viscosity. Because it is difficult.

In each of the above-mentioned inventions, it is desirable from the environmental point of view that the plasticizer is a non-volatile ester type, since the mastic sealer after coating does not lose its aging over time and the plasticizer does not evaporate little.

Further, it is desirable that a foaming agent is further added to form a fine foaming formulation, because it can absorb variations in assembly between the outer panel and the inner panel and also has good vibration absorption.

[0029]

[Detailed Description of Means] Next, each component of the above means will be described in detail. In the following description, "part" indicating the blending amount
Means "parts by weight" unless otherwise specified.

A. One of the mastic sealers of the present invention (hereinafter, may be simply referred to as “sealer”) is a vinyl chloride resin (polyvinyl chloride: hereinafter “PVC”) and a liquid synthetic rubber, which are a plasticizer and a filler. The basic configuration is a configuration in which the viscosity is adjusted and a thermosetting resin is further added as an adhesion-imparting agent.

(1) PVC is used because it has a base material (matrix) function, is easy to secure the wettability (adhesion) to a sheet metal when the sealer is heated (when PVC is melted), and is inexpensive. Things.

As PVC, a powdery PVC used for processing a paste produced by emulsion polymerization, suspension polymerization, bulk polymerization, solution polymerization, or the like can be used. Further, it includes not only a homopolymer (homopolymer) but also a copolymer (copolymer) mainly composed of vinyl chloride. As the copolymer, a vinyl chloride / vinyl acetate copolymer obtained by copolymerizing with vinyl acetate to lower the softening point can obtain a predetermined softness by reducing the relative amount of the plasticizer. desirable.

The degree of polymerization of PVC is 800 to 200.
0, preferably 1000 to 1700. If the degree of polymerization is too low, problems tend to occur in the strength. If the degree of polymerization is too high, a relatively large amount of a plasticizer is added to obtain a predetermined viscosity (flowability) and softness after curing. There is a need to.

(2) The liquid rubber is presumed to have rubber-like elasticity. Liquid rubber means a molecular weight of 2,000 to 10
A liquid at room temperature of about 000. But not necessarily, at both ends of the polymer chain, -OH, -SH, -NH _2,
Stabilized by adding a functional group such as -COOH, -NCO, -Br, etc. ("Supplementary Edition New Synthetic Rubber Handbook" edited by Shu Kamihara et al., 3rd person (Showa 42-11-30), Asakura Shoten, p. 21) reference).

The rubber may be a conventional general-purpose liquid low-molecular-weight butyl rubber, liquid polyisoprene, polybutadiene, 1,2-polybutadiene, polychloroprene, or the like.
000, the nitrile content is 15 to 50% (preferably 25 to 3
0%) of liquid NBR. NBR is easy to respond to the oil resistance required for the sealer of the present invention,
This is because it has excellent compatibility with a non-volatile plasticizer (usually having polarity) used in place of the organic solvent.

Here, the compounding amount of the liquid rubber to 100 parts of PVC is 20 to 100 parts, preferably 40 to 80 parts. If the compounding amount of the liquid rubber is too small, it is difficult to obtain rubber-like elasticity in the sealer after heat treatment (curing). It is difficult to secure the property.

(3) The plasticizer has a function of imparting fluidity before application to the sealer and flexibility to secure buffering properties to the sealant layer after heat treatment (after heat curing).

The liquid rubber is not particularly limited as long as it has compatibility or miscibility with the auxiliary material. Aromatic carboxylic acid esters, aliphatic dibasic acid esters, phosphoric acid esters, epoxy plasticizers and the like may be used, but phthalic acid diesters of higher alcohols having 7 to 12 carbon atoms are usually used. desirable.

If the number of carbon atoms is too small, volatility resistance, cold resistance,
If the carbon number is too large, miscibility with liquid rubber or the like may be lacking. In addition, a phthalic acid diester of a higher alcohol having 7 or less carbon atoms, for example, diethyl phthalate, dibutyl phthalate, or the like may be used in combination to increase plasticization and compatibility.

Specifically, di-2-ethylhexyl phthalate (DOP), di-n-octyl phthalate, dinonyl phthalate, diisononyl phthalate (DINP), diisodecyl phthalate, diundecyl phthalate and the like can be preferably used. .

Here, the blending amount of the plasticizer with respect to 100 parts of PVC is 100 to 500 parts, preferably 200 to 4 parts.
00 parts. If the blending amount of the plasticizer is too small, it is difficult to obtain a predetermined discharge fluidity (viscosity) with a sealer before coating.
Since the sealer viscosity is too low, sagging is likely to occur at the time of application, and it is difficult to secure shape retention at the time of application.

(4) The filler acts to adjust the viscosity (application of the sealer and maintain the form of the coating film) during the application of the sealer and imparts the heat-resistant form-retaining ability to the heat-treated sealant layer. It is.

The filler is not particularly limited as long as it can mutually impart structure forming ability (form retention ability) due to cohesion, but heat resistance and form retention (gelling strength)
In view of the above, inorganic fine particles are used. In addition, powdered organic fillers such as amino resin, cellulose, phenolic resin, wood flour, and cork may be appropriately used in combination.

As the inorganic fine particles, light calcium carbonate, heavy calcium carbonate, talc, clay, magnesium silicate, magnesium carbonate, barium sulfate, carbon black, silica powder (white carbon), diatomaceous earth, mica and the like can be used. is there. In particular, of these,
Calcium carbonate is preferred. In the case of carbon black and silica powder, the viscosity tends to be high and the thixotropic property is too high, which may adversely affect the coating workability (including the discharge workability).

The compounding amount of the filler with respect to 100 parts of PVC is 200 to 600 parts, preferably 300 to 500 parts. If the compounding amount of the filler is too small, it is difficult to secure the heat-resistant form retention ability to the sealant layer, and if it is too large, it is difficult to secure the sealer workability and the flexibility to ensure the buffering property of the heat-treated sealant layer.

(5) Thermosetting resin after electrodeposition coating (heating)
In order to secure the adhesiveness to the sheet metal.

The thermosetting resin is not particularly limited as long as it can secure the adhesiveness to the sheet metal, and a phenol resin, a thermosetting polyurethane, a thermosetting acrylic resin, an epoxy resin, or the like, which hardly reacts with isocyanate, can be used. However, an amine-curable epoxy resin having good adhesion to sheet metal is desirable. .

As the epoxy resin, bisphenol A
Type, bisphenol F type, rubber-modified epoxy resin, glycerin type epoxy resin, novolak type epoxy resin, alicyclic epoxy resin, epoxidized soybean oil and the like can be used. In general, a liquid epoxy resin is used from the viewpoint of ease of preparation and reactivity, but a part or all of the liquid epoxy resin may be replaced with a solid epoxy resin.

A curing agent is used in combination with these epoxy resins. The curing agent may be a carboxylic acid type, but is preferably an amine type from the viewpoint of water resistance. That is, the epoxy resin is preferably of an amine-curable type.

B. In the above configuration, the greatest feature of the present invention is that polyisocyanate is added as a cured film forming component.

The polyisocyanate forms a cured film on the surface of the sealant layer (mastic sealer) by utilizing the principle that NCO groups react with moisture in the air to cure (see FIG. 4B). That is, the solvent-free mastic sealer to which isocyanate is added is applied to a panel such as a steel plate, and then reacts with moisture in the air to form a cured film, and the sealant layer before the heat treatment has a function of withstanding a washing shower.

The polyisocyanate is not particularly limited as long as it is water-curable without heating.
(a) Aliphatic isocyanate, (b) Aromatic isocyanate and the like can be used.

(A) Aliphatic isocyanate In addition to the original aliphatic isocyanate, an alicyclic isocyanate is included, and hexamethylene diisocyanate (HMD)
I), xylene diisocyanate (XDI), hydrogenated xylene diisocyanate (hydrogenated XDI), 4,4'-methylenebisdicyclohexyl diisocyanate (H12M
DI), methylcyclohexyl diisocyanate (hydrogenated TDI), and isophorone diisocyanate (IPD
From the viewpoint of handling, there can be mentioned so-called non-yellowing products such as dimers, trimers, trimethylolpropane adducts and prepolymers obtained by polymerizing them.

(B) Aromatic isocyanates 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as "MDI"), crude MDI, liquid MDI, tolylene diisocyanate, phenylene diisocyanate, etc. Furthermore, from the viewpoint of handling, dimers, trimers, trimethylolpropane adducts, prepolymers, and the like obtained by polymerizing these are exemplified.

Here, when a prepolymer is used as the polyisocyanate, it may be a polyester type or a polyether type, but it is desirable to use a reaction product of a liquid polybutadiene having a terminal OH and a diisocyanate compound. . This is because they have excellent water resistance as compared with the case where a polyester polyol or a polyether polyol is used as the polyol.

The blending amount of the polyisocyanate is P
The amount of NCO is 2 to 12 parts, preferably 4 to 10 parts with respect to 100 parts of VC. If the amount of NCO is too small, it is difficult to form a cured coating film. If the amount is too large, the rigidity of the mastic sealer becomes too high, and it becomes difficult to obtain the flexibility required for the sealer.

When a monomer, dimer, trimer or the like having a high NCO content (25 wt% or more) is used as the polyisocyanate, there is a problem even if a solid polyamine having a melting point near the heating is used as a curing agent. Absent.

(5) Other chemicals to be incorporated into the sealer of the present invention include stabilizers, foaming agents, tackifiers and the like.

Among them, it is desirable to add a stabilizer for preventing dehydrochlorination, since it is based on PVC.

The stabilizer may be any one which is usually used for PVC, for example, metal soaps such as zinc stearate, barium stearate, calcium stearate, aluminum stearate, dibutyltin dilaurate, dibutyltin maleate, and the like. Organic tin compounds such as dibutyltin mercaptide; dibasic phosphorous acid; tribasic lead sulfate; and lead compounds such as lead white.

Further, the sealer of the present invention has
From the standpoint of absorbing assembly dimensional errors and increasing the cushioning action (vibration absorption / sound insulation) of the sealant layer, it is desirable to mix a small amount of a foaming agent to form a fine foaming formulation.

As the foaming agent, azodicarbonamide (ADCA), azobisisobutyronitrile (AIB)
N), barium azocarboxylate, dinitrosopentamethylenetetramine (DPT), p, p'-oxybis (benzenesulfonylhydrazide) (OBSH), paratoluenesulfonylhydrazide (TSH), hydrazodicarbonamide (HDCA), etc. Organic blowing agents that exhibit sharp exothermic decomposition are preferred.

The tackifier is appropriately added to ensure adhesion, and includes a coumarone indene resin, polybutene,
Terpenes and the like can be mentioned.

C. A second feature of the present invention is that when an amine-curable epoxy resin is used as a thermosetting resin, the amine-curable epoxy resin loses a primary amino group between an epoxy resin and a primary amine. And a secondary amino group-introduced product prepared by the above reaction.

The secondary amine having a melting point of about 100 ° C. cannot be used because it is usually liquid and hardly any solid with low reactivity.

By reacting a primary amine having a melting point of about 100 ° C. or a liquid with an epoxy resin as an amine to form a secondary amino group-introduced compound having no primary amino group,
The reactivity is reduced, and the epoxy resin substantially does not undergo curing at room temperature than the case where a primary amine having a melting point of around 100 ° C. is used. That is, by pre-reacting the epoxy resin and the primary amine, the epoxy resin has a thermosetting property at a relatively low temperature of about 150 ° C., and even if the temperature of the electrodeposition furnace is reduced to about 150 ° C., Sheet metal adhesion after curing can be secured.

The primary amines that can be used here include:
There is no particular limitation as long as the epoxy resin and the primary amino group are reacted so as to disappear so that the reaction can be stopped in a low viscosity state (uncured state).

In particular, 2- (2-phenyl-1-imidazolyl) ethyleneamine represented by the following formula (melting point: 99 to 1)
A primary monoamine having a melting point of about 100 ° C. (eg, 00 ° C.) is desirable. Since it is a monoamine, the primary amino group is easily lost, and even if some unreacted amine remains, the melting reaction of the unreacted amine is around 100 ° C., which is higher than room temperature, so that the curing reaction at room temperature is excessive. This is because it does not progress and it is difficult to shorten the pot life due to the increase in viscosity.

[0069]

Embedded image

The following amines can be used as the primary amine.

(A) Aliphatic primary amine (monoamine) This is represented by the general formula RNH ₂ (R: alkyl group having 1 to 16 carbon atoms), specifically, methylamine, ethylamine, propylamine, isopropyl Amine, butylamine, amylamine, hexylamine, octylamine, nonylamine, decylamine, undecylamine,
Dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, cetylamine and the like can be mentioned.

(B) Aliphatic diamine: an aliphatic diamine represented by the general formula H ₂ NRNH ₂ (R: an alkylene group having 1 to 10 carbon atoms); ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine , 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane 2,5-dimethylhexamethylenediamine and the like.

(C) Polyetherdiamine General formula H ₂ N (CH ₂ ) _n O (CH ₂ CH ₂ O) _m (C
H ₂ ) _n NH ₂ (n = 1 to 3, m = 0 to 5) and the like.

(D) Aliphatic polyamine General formula H ₂ N [(CH ₂ ) ₁ NH (CH ₂ ) _m NH] _n
Diethylenetriamine, iminobispropylamine, bis (hexamethylene) triamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, and tri (methyl) represented by H (l, m = 1 to 6, n = 1 to 3) Amino) hexane, dimethylaminopropylamine, methyliminobispropylamine and the like.

(E) Alicyclic amines Examples thereof include cyclopropylamine, cyclobutylamine, cyclopentylamine, cyclohexylamine and isophoronediamine.

(F) Aromatic amine aniline, o, m, p-toluidine, benzylamine,
α, β-Naphthylamine, o, m, p-phenylenediamine and the like can be mentioned.

B. Preparation of Sealer Composition The preparation of the sealer is performed by using a liquid raw material such as a liquid synthetic rubber, a plasticizer, and an epoxy resin which is a liquid thermosetting resin from room temperature to 60%.
After stirring and mixing for 20 to 40 minutes while vacuum dewatering in a temperature range of ８０80 ° C., powder materials such as PVC, powdered inorganic filler, and foaming agent are vacuum-dewatered at the same temperature conditions for 30 to 90 minutes.
After stirring uniformly for a minute, polyisocyanate is added, and the mixture is further stirred for 10 to 20 minutes. In this preparation method, the polyisocyanate is a highly reactive MDI
It is desirable to use This is because the formation of a cured film is accelerated.

When a secondary amino group-introduced product is used as the epoxy resin, it is desirable to prepare it as follows.

That is, a liquid synthetic rubber, which is a liquid raw material,
After mixing and stirring the primary amine together with the plasticizer and the amine-curable epoxy resin in a temperature range of 60 to 80 ° C. under vacuum for 20 to 40 minutes, under the same temperature conditions, add the polyisocyanate. 10-20 while vacuum dewatering
Then, the mixture is prepared by adding powder materials such as PVC, a powdered inorganic filler, and a foaming agent and mixing for 30 to 90 minutes. The reason why the addition time of the polyisocyanate is different from the above case is that if the primary amino group does not disappear by reacting with the epoxy group, it reacts with the NCO group of the isocyanate to thicken and harden the sealer, thereby increasing the pot life. This is undesirable because it leads to shortening of the period.

The stirring and mixing for the preparation of the respective sealers is performed by a stirrer equipped with a rotating / revolving type so-called planetary type stirring blade (hereinafter referred to as a “planetary mixer”) equipped with a rotating blade. However, it is desirable because the powder component has good stirring and dispersibility with respect to the liquid component.

C. Usage Mode of Sealer Sealer 12 thus prepared is, as in the prior art, before the outer panel 14 and the inner panel 15 are set and integrated,
It is applied to a plurality of predetermined places on the outer panel 14 in a dumpling shape having a diameter of 2 to 3 cm for use. In addition, as a material of each panel, a metal plate such as an aluminum plate can be used in addition to the steel plate.

At this time, the viscosity is adjusted to a level at which the coating operation is easy (for example, 150 Pa · s), and there is no problem in the coating operation (sealer discharge operation).
As described above, the integrated panel assembly is shower-washed as a pretreatment for electrodeposition coating, but the sealer does not scatter as in the prior art (FIG. 4).
(A)). The reason for this is that the moisture (moisture) in the air causes the polyisocyanate component to polymerize and solidify during the transportation to the cleaning shower step, forming a cured film on the surface of the sealer (see FIG. 4B). ).

Further, in the electrodeposition baking step, 160
By heating to 180 ° C., the curing agent having a melting point of 150 ° C. or more is melted and dispersed in the epoxy resin, and the epoxy resin is cured by heating. By this heat hardening action, a sufficient adhesive strength between the steel sheet and the steel sheet can be obtained.

When a secondary amino group-introduced epoxy resin is used as the thermosetting resin, the introduced secondary amino groups are activated by heating at 150 ° C. or lower, and the viscosity of the sealer increases at room temperature. The hardening reaction which causes hardly progresses, and the pot life is not shortened.

Therefore, the electrodeposition baking temperature was set to 150 ° C.
Also in the following, a sufficient adhesive strength can be ensured with a panel such as a steel plate. Furthermore, since the polyurethane which forms a cured film formed by the reaction between polyisocyanate and water also has secondary amino groups, the epoxy groups are ring-opened to generate hydroxyl groups. Contributes with epoxy resin.

[0086]

EXAMPLES (1) Hereinafter, examples performed together with a conventional example to confirm the effects of the present invention will be described. In addition,
The compounding amounts in the conventional examples and Examples 1 and 2 were based on the compounding formulations shown in Table 1.

<Conventional Example 1> Planetary mixer (5
L: manufactured by Inoue Manufacturing Co., Ltd.)
Charge DINP, epoxy resin, PVC stabilizer, 60
Stirred at 150C for 15 minutes. Next, PVC, dicyandiamide, light calcium carbonate, and ADCA as a foaming agent were charged as powder raw materials and stirred for 1 hour. Finally, a sealer was prepared by stirring and defoaming for 5 minutes.

<Example 1> Liquid NBR, DINP, epoxy resin and PVC stabilizer (powder) were charged into the same planetary mixer as in Conventional Example 1 and stirred at 60 ° C for 30 minutes at a vacuum of 10 Torr. Dehydrated. Next, the remaining powder raw material PVC, light calcium carbonate, ADCA and dicyandiamide were added, and the mixture was stirred at a degree of vacuum of 10 Torr for 1 hour. Subsequently, a urethane prepolymer was added and the mixture was stirred and defoamed to prepare a sealer.

<Example 2> Liquid NBR, DINP, epoxy resin and primary amine (powder) were charged into the same planetary mixer as in Conventional Example 1 at 30 ° C. for 30 minutes while stirring at 60 ° C. for 30 minutes. The epoxy resin is reacted with a primary amine while dehydrating to prepare a secondary amino group-introduced epoxy resin.
Stir and mix for 5 minutes. The remaining powder raw materials, PVC, light calcium carbonate and ADCA were charged, and the degree of vacuum was 10 Torr.
For 1 hour to prepare a sealer.

(2) Next, using the respective sealers prepared as described above, tests of the following items were performed according to the following methods.

Tensile shear test A steel plate of 100 × 25 × 1.0 mm was immersed in rust-preventive oil to stand upright overnight to obtain an oil-level steel plate. This was coated with a sealer via a spacer having a thickness of 1.0 mm, and was fixed with a clip so that pressure was applied to the bonded portion.

This was put in a thermostat adjusted to 180 ° C. and 140 ° C., held for 20 minutes, and baked and hardened to prepare each test piece.

Each test piece was attached to a tensile tester, and the shear adhesive strength was measured at a tensile speed of 5 mm / min.

Shower resistance test A sealer was applied to a 150 × 70 × 0.8 mm oil-side steel plate, and 150 × 25 ×
A 0.8 mm oil-side steel plate was pressed and fixed with bolts, and the protruding portion was cut off.

One hour after application of the sealer, an angle of 45 ° from a distance of 700 mm, a pressure of 490 kPa (5 kgf / cm ² ), and a temperature of 50 ° C
Of warm water for 1 minute to check for deformation or scattering.

Viscosity Each prepared sealer was placed in a container, the initial viscosity was measured, the container was sealed, left for a predetermined number of days, taken out, and the viscosity was measured. Each measurement condition was as follows.

Viscometer used: BH type rotational viscometer (rotor
No. 7, rotation speed 2 rpm) Initial viscosity (Pa · s): Measurement temperature 22 ° C Temporal change (%): Measurement temperature after elapse of 40 ° C x 20 days
22 ° C. (2) Table 2 shows the results of the evaluation test.

It can be seen that each of the examples is superior in shower resistance and has an increased adhesive strength after thermosetting as compared with the conventional example. In addition, it can be seen that Example 2 in which a secondary amino group-introduced product was used as the epoxy resin had excellent adhesive strength to a sheet metal even after curing at a low temperature of 150 ° C. or less.

Further, it can be seen that in each of the examples, the viscosity was low and the viscosity did not increase with time as in the prior art.

[0100]

As described above, the mastic sealer of the present invention has excellent washing shower resistance before heat treatment (electrodeposition baking), and has sufficient adhesive strength to a metal panel after heat treatment.

That is, since the conventional solvent-free one-pack type mastic sealer does not react at room temperature, a cured film is not formed on the surface of the sealer. Therefore, the sealer before the heat treatment existing between the steel sheets easily falls off and scatters by the washing shower (see FIG. 4A).

However, in the present invention, by containing the polyisocyanate, the NCO group of the isocyanate present on the surface of the sealer after coating reacts with water in the air, and the polyurethane-type cured coating film before the heat treatment is formed. Formed on the application sealer surface. Therefore, the sealer does not fall off, scatter or deform due to the washing shower (see FIG. 4B).

When a secondary amino group-introduced compound is used as the epoxy resin, the introduced secondary amine is activated by heating at 150 ° C. or lower, and at ordinary temperature, the curing causes a rise in the viscosity of the sealer. The reaction is slower than when a primary amine having a melting point of around 100 ° C. is used, and the pot life is not shortened.

The reason is that the secondary amino group has lower reactivity than the primary amino group. Furthermore, even when a polyisocyanate having a high HCO content and a high reactivity is used, the secondary amino group-introduced epoxy resin has no primary amino group, and the polyisocyanate contributes to the curing of the epoxy resin. It is also desirable from the viewpoint of preventing shortening of pot life.

[0105]

[Table 1]

[0106]

[Table 2]

[Brief description of the drawings]

FIG. 1 is a back view of a bonnet showing an example of applying a mastic sealer.

FIG. 2 is a partial cross-sectional view taken along a line 2-2 in FIG. 1;

FIG. 3 is a schematic flowchart showing a manufacturing process of an automobile.

FIG. 4 is a sectional view for explaining the operation of a conventional example and the mastic sealer of the present invention.

[Explanation of symbols]

 12 mastic sealer 14 outer panel 16 inner panel B bonnet

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akira Mabuchi 1 Ochiai Nagahata, Kasuga-cho, Nishi-Kasugai-gun, Aichi Prefecture Inside Toyoda Gosei Co., Ltd. No. Toyoda Gosei Co., Ltd. (72) Inventor Shigeki Watanabe 25, Ueikeike, Yoshiwara-cho, Toyota City, Aichi Prefecture Inside Araco Co., Ltd. ) Inventor Kazuichi Ishiguro, 25, Ueikeike, Yoshiwara-cho, Toyota-shi, Aichi Prefecture Araco Co., Ltd. 100 Kanayama, Ichiriyama-cho, Kariya-shi, Japan F-term in TOYOTA vehicle stock (reference) 4J040 CA051 CA052 CA071 CA072 CA101 CA102 CA151 CA15 2 DA141 DA142 DC021 DN051 DN052 EB032 EC032 EC062 EC072 GA03 GA05 GA07 GA14 GA20 GA24 HA026 HA196 HA306 HA316 HB34 HC01 HC14 HC16 HC18 HC24 JA12 JB02 JB04 KA31 KA37 KA42 LA05 LA06 LA11 MA02 MA03 MB05 NA03 Q30AQ

Claims (9)

[Claims] 1. A solventless one-pack mastic sealer in which a vinyl chloride resin and a liquid synthetic rubber are adjusted in viscosity with a plasticizer and a filler, and further a thermosetting resin is added as an adhesion-imparting agent. A mastic sealer, wherein polyisocyanate is added as a cured film forming component. 2. The mastic sealer according to claim 1, wherein the thermosetting resin is an amine-curable epoxy resin. 3. The mastic sealer according to claim 2, wherein when the polyisocyanate is a prepolymer, the prepolymer is a reaction product of a liquid polybutadiene having terminal OH and a diisocyanate compound. . 4. The mastic sealer according to claim 3, wherein the plasticizer is a non-volatile ester type. 5. The mastic sealer according to claim 1, wherein a foaming agent is further added to form a fine foaming formulation. 6. A non-solvent, one-liquid type obtained by adjusting the viscosity of a vinyl chloride resin and a liquid synthetic rubber with a plasticizer and a filler, and further adding an epoxy resin as a thermosetting resin as an adhesion-imparting agent. In the mastic sealer, the epoxy resin is a secondary amino group (imino group) -introduced product prepared by reacting an epoxy resin with a primary amine so that the primary amino group disappears, A mastic sealer comprising isocyanate added as a cured film forming component. 7. The method according to claim 7, wherein the primary amine is 2-phenyl-1-.
The mastic sealer according to claim 6, which is an imidazoline derivative. 8. The mastic sealer according to claim 6, wherein the plasticizer is a non-volatile ester type. 9. The mastic sealer according to claim 6, wherein a foaming agent is further added to form a fine foaming formulation.