JPH06157857A - Sealing material composition - Google Patents

Abstract

PURPOSE:To obtain a sealing material compsn. suitable for applying with a slit nozzle and for automation with a robot by selecting a plastisol mainly comprising a vinyl chloride resin and having specified viscosity characteristics. CONSTITUTION:This compsn. is a plastisol which mainly comprises a vinyl chloride resin and is adjusted so that the ratio of the viscosity at 20 deg.C under a shear rate of 4.2sec<-1> to that under a shear rate of 62sec<-1> is 5.5 to 7.5 and the ratio of the viscosity under a shear rate of 10<3>sec<-1> to that under a shear rate of 10<4>sec<-1> is 1.2 to 1.8. The compsn. has a flowability suitable for applying with a slit nozzle, gives a bead undergoing a small change in width with the change in temp. or application length and having a very smooth surface, and has good gas-filling properties.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyvinyl chloride (PVC) plastisol-based sealant composition having flow characteristics suitable for ejection from a slit type nozzle and suitable for automatic application by a robot.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
The PVC plastisol-based sealing material has been accurately applied to a target object to be coated, such as a steel plate joint, usually by hand in an automobile coating line.

However, in recent years, the application of the sealing material in the automobile coating line has been automated, and the application of the application by the robot is rapidly increasing. Since it is difficult to apply the sealing material to a precise position by using a robot like this, conventionally, a method of applying a wide bead shape by atomizing injection such as airless spray to compensate for positional deviation is generally used. Has been done in.

However, in this method, since the spray is sprayed in a fan shape from the discharge port, the shape such as the width and thickness of the bead changes depending on the distance between the object to be coated and the discharge port or the temperature and viscosity of the sealing material. There is a problem. In order to prevent this, precision of mechanical surface such as control of sealing material pressure and coating distance is mainly required,
This is practically difficult to meet.

Further, in the atomization treatment method such as the airless spray method, the sealing material to be used needs to have high thixotropy, and therefore, there is a problem in terms of smoothness of the bead surface (finished appearance). However, it is the actual situation that none of these atomized injection methods has a finish comparable to that of the conventional manual work method. Moreover, in the atomizing injection method, since the sealer coating speed is high and it is not a continuous film, there is a problem that when the gap of the seal portion is 2 mm or more, the seal cannot be performed as shown in FIG. .

For this reason, a PVC plastisol-based sealing material composition which can be directly applied in a wide width by a so-called slit type nozzle having a straight slit shape with a narrow discharge port, instead of being applied in a fan shape as in the atomization treatment method. Things are desired.

Conventionally, in JP-A-62-246981, a vinyl chloride resin is used as a main component, a plasticizer,
Contains a thixotropic agent, a powder filler, an adhesion imparting agent and a heat stabilizer, and has a viscosity at low shear at 20 ° C. of 12,000 to.
A sealing material has been proposed, which is characterized in that the viscosity at low shear and the viscosity at high shear is 2,000 cps of 1.5 to 2.5, which is a seal suitable for coating work by a robot. Although it is a material, there is a great demand for a sealing material composition suitable for a slit type nozzle capable of satisfactorily filling and coating a gap as shown in FIGS.

The present invention has been made in view of the above circumstances, has characteristics suitable for robot coating by such a slit type nozzle, has little change in coating bead width due to temperature and coating distance, and has a smooth bead surface. It is an object of the present invention to provide a PVC plastisol-based sealant composition having good properties and good gap filling properties.

[0009]

MEANS TO SOLVE THE PROBLEMS The inventors of the present invention have conducted extensive studies in order to achieve the above object, and as a result, in a sealing material composition comprising plastisol containing a vinyl chloride resin as a main component, shearing at 20 ° C. The relationship between the modulus and the viscosity is that the viscosity at a shear rate of 4.2 sec ^{-1 and} the viscosity of 62 sec ^-1
The viscosity ratio in the low shear rate region is 5.5 to 7.5, and the viscosity ratio in the high shear rate region between the viscosity of 10 ³ sec ^{-1 and} the viscosity of 10 ⁴ sec ^-1. By adjusting to 1.2 to 1.8, it has flow characteristics suitable for coating with a slit-type nozzle, there is little change in the width of the coating bead (pattern) due to temperature and coating distance, and the bead surface has a smooth surface. It was found that the gap filling property was very good.

That is, generally, the surface flow (leveling) property and the run-down resistance (drip resistance) have the opposite properties, but as described above, the viscosity in the low shear rate region and the high shear rate region is high. The PVC plastisol-based sealant composition in which the ratio is properly adjusted can achieve both good leveling properties and sagging resistance, and has the above-mentioned unprecedented flow characteristics. That is, as the sealing material composition, thixotropy, a large yield value is required, and good dischargeability is obtained by utilizing the viscosity decrease due to the destruction of the gel structure at the time of high shear received during discharge, and further after coating. Is designed to restore the gel structure in a short period of time to reduce flow and maintain the bead shape. That is, when the structure is recovered too early, the leveling property is hardly exhibited, and the unevenness of the bead surface remains as it is immediately after the ejection, which is not preferable in appearance. On the other hand, if the structural recovery is too slow, the flow will not stop, and the bead shape will not be maintained, leading to dripping. On the other hand, in the sealant composition of the present invention, by having the above-mentioned flow characteristics, it is possible to obtain an appropriate gel structure recovery time from the state of being subjected to this shearing to being unsheared and of standing. It is possible.

The sealing material composition having such a flow characteristic can be discharged at a relatively low pressure when it is applied using a slit type nozzle having a straight slit shape with a narrow discharge port, and it is applied in a fan shape. However, the bead shape is not easily affected by the temperature, pressure, and coating distance of the material because it is applied directly from the discharge port, and it is easy to obtain a certain shape. Since it does not require high thixotropy, the bead surface after application tends to flow and the surface becomes smooth, and since it has moderate viscosity, it is an excellent slit type that does not penetrate even in a gap of 2 to 5 mm width. It has nozzle suitability.

The present invention will be described in more detail below. The sealing material composition of the present invention comprises a plastisol containing a vinyl chloride resin as a main component, and the plastisol has a relationship between shear rate and viscosity at 20 ° C. , Viscosity of 4.2 sec ^-1 and 62 se in the low shear rate region
The viscosity ratio to the viscosity of c ^-1 is 5.5 to 7.5, preferably 6.5 to 7.5, and 10 ³ se in the high shear rate region.
The viscosity ratio between the viscosity of c ^{-1 and} the viscosity of 10 ⁴ sec ^-1 is 1.2.
A PVC plastisol having a two-point relative viscosity ratio (thixotropic property) of 1.8 to 1.8, preferably 1.3 to 1.6 is used, and the plastisol has such a flow characteristic, so that a slit type nozzle is obtained. 20 to 30 mm
It was possible to obtain a film having a continuous width and to obtain good shape and sealing property.

[0013] Here, when the viscosity ratio of of 4.2 sec ^-1 and 62sec ^-1 low shear rate region is lower than 5.5, resulting dripping after coating deposition, whereas, greater than 7.5 becomes the structure The recovery will be too early, leaving unevenness on the bead surface,
It is not good in appearance. Also, in the high shear rate region, 10 ³ se
When the viscosity ratio at c ⁻¹ and 10 ⁴ sec ⁻¹ is lower than 1.2, the discharge shape from the slit type nozzle is poor, and 20 to 3
If the width does not become 0 mm wide, on the other hand, if it exceeds 1.8,
The discharge width is easily affected by changes in temperature, pressure, and material viscosity, and when discharged at high temperatures, the material viscosity is too low, so the width is too wide, and the discharge direction is split into two directions, resulting in continuous film formation. I can't get it.

In order to obtain a sealing material composition having such a flow characteristic, the composition and composition of the plastisol can be appropriately selected.
.About.28% by weight, of which 0.7 to 1 .mu.m and 2.
It is preferable to use PVC plastisol in which the vinyl chloride resin having a particle size distribution having two peaks of 5 to 5 μm is 3 to 15% by weight of the whole composition and further contains a plasticizer, a flow regulator and a filler. . In particular, a vinyl chloride resin having an average degree of polymerization of 600 to 700 or a chlorinated rubber containing 50 to 60% by weight of chlorine dissolved in a plasticizer or a solvent is used as a flow regulator, and a surface treatment is performed as a filler. 15 to 20% by weight of calcium carbonate based on the total composition
The compounded one is preferable.

Explaining each component specifically, in order to obtain the above-mentioned flow characteristics among vinyl chloride resins,
It is effective to blend a vinyl chloride resin having a particle size distribution having two peaks of 0.7 to 1.0 μm and 2.5 to 5 μm in an amount of 3 to 15% by weight, preferably 5 to 10% by weight of the entire composition. Is. As such a vinyl chloride resin, a copolymer obtained by emulsion polymerization of a vinyl chloride monomer and vinyl acetate can be used.

As the vinyl chloride resin other than the vinyl chloride resin having the above two peaks, a vinyl chloride homopolymer, a copolymer with vinyl acetate and the like which are commonly used can be used. As these vinyl chloride resins, those obtained by any polymerization method such as emulsion polymerization, suspension polymerization, and microsuspension polymerization can be used, and 5 to 10% by weight of the entire composition can be used. In addition, the compounding amount of the entire vinyl chloride resin is 18 to 28 of the entire composition.
%, Preferably 21 to 25% by weight.

As the plasticizer, DOP, DINP, DI
Uses phthalic acid dialkyl ester such as DP in an amount of 8 to 12% by weight of the entire composition, polyester such as alkylbenzyl phthalate in an amount of 15 to 20% by weight, and epoxy such as glycidyl ether ester type epoxy resin in an amount of 1 to 5% by weight. It is preferable that the above-mentioned flow characteristics can be obtained. In addition to these plasticizers, for example, trimellitic acid-based or sulfonic acid-based plasticizers may be used.

It is also effective to add 1 to 3% by weight of the olefinic hydrocarbon solvent to the composition in order to adjust the discharge property.

The flow regulator has an average degree of polymerization of 600 to
The entire composition is a masterbatch prepared by previously dissolving 700 vinyl chloride resin or chlorinated rubber containing 50 to 60% by weight of chlorine in 10 to 30% by weight of a solvent such as a plasticizer such as DOP or a high boiling aromatic hydrocarbon. 0.5 to 3% by weight, particularly 0.8 to 1.3% by weight is preferable.

Further, the surface-treated calcium carbonate is used as a filler or a thixotropy-imparting agent in 15 to 15% of the total weight of the composition.
It is effective to add 20% by weight to obtain the above-mentioned flow characteristics. Examples of the surface treatment method include those whose surface is coated with stearic acid, calcium stearate, rosin acid and the like.

As other fillers, for example, untreated calcium carbonate, barium sulfate, silica, talc, clay and the like can be blended in an amount of 5 to 15% by weight of the whole composition.

In addition, adhesion promoters such as polyaminoamine, acrylic acid ester, epoxy, phenol, blocked urethane resin, etc., and further stabilizers, pigments and the like can be added.

The sealant composition of the present invention can be obtained by uniformly mixing the above components with a kneader or the like.

[0024]

EXAMPLES Hereinafter, the present invention will be specifically shown by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Examples, Comparative Examples 1 to 5] The components having the compounding ratios shown in Table 1 were kneaded using a planetarium type kneader and a three-roll mill to prepare a sealing material composition.

With respect to the obtained composition, viscosity characteristics, coating characteristics, finish properties, gap filling properties, and sagging resistance were measured according to the following methods. Viscosity characteristics Using a continuously variable RHEOMAT-115 rotary viscometer (manufactured by CODIX & PC-LABO) of shear rate, shear rate at 20 ° C 4.2, 62, 10 ³ , 10 ⁴
with measuring the viscosity at sec ^-1, it was determined value at a shear rate between two points viscosity ratio 4.2 / 62 and ^{103/10 4.} At a temperature of 20 ° C., the shear rate was changed from 0 sec ⁻¹ to 35.4 sec ⁻¹ for 25.4 sec ⁻¹ , the state was maintained for 120 seconds, and then again returned to ⁰ sec ⁻¹ for 3 seconds to measure the shear rate history.

Here, the shear rate history is a model of how the sealant composition is ejected from the nozzle in this test, and is adhered to and fixed on the article to be coated. The composition is ejected from the nozzle. It shows a state in which the state where the viscosity is reduced due to shearing (shearing) at the time of coating, the coating is not applied and shearing is resumed, and the viscosity is recovered is reproduced.

The results of the compositions of Examples and Comparative Examples are shown in FIGS.
The shear rate is 25.4 as shown in FIG. 4 (Example).
At the time of sec ^-1 (indicated by a in the figure), there is little decrease in viscosity,
And the composition that recovers as much as possible to the original viscosity when it is not subjected to shearing is excellent in the self-leveling property of the coating film after application,
A smooth seal shape can be obtained, which contributes to uniform sealing properties. On the other hand, as shown in FIGS. 5 and 6 (comparative example), the viscosity at the point a is largely decreased, the recovery is slow after not undergoing shearing, and it is difficult to return to the original viscosity.
Only a film that gives good uniformity can be obtained. Coating characteristics A slit type nozzle with a diameter of 0.35 x 2 mm or a spray is used to separate from the object to be coated by about 40 mm, and coating is performed at a coating speed of 400 mm / sec. did. Finishing property By visually observing the appearance of the product coated in the coating property test,
If the surface was smooth, it was evaluated as ◯, and if the surface had irregularities, it was evaluated as x. Gap filling property Coating was performed under the same conditions as the above coating characteristics toward a gap between members having a gap of 3 mm as shown in FIG. It was evaluated as x. Sagging resistance After application to a semi-circular bead with a diameter of 10 mm and a length of 100 mm, hold the application part vertically and check the flow rate of the application part when heated at 140 ° C. If the flow rate is less than 8 mm, ◯, 8 to 10 mm was evaluated as Δ, and more than 10 mm was evaluated as x.

The results are also shown in Table 1.

[0030]

[Table 1] (Note) PVC homopolymer (1) average degree of polymerization 1300 obtained by emulsion polymerization method, vinyl chloride homopolymer PVC homopolymer having average particle size 1 μm (2) average degree of polymerization 1000 obtained by suspension polymerization method, the average particle vinyl chloride homopolymer PVC · PVAc copolymer (3) of diameter 25μm vinyl acetate obtained by emulsion polymerization contain 5 wt%, average polymerization degree of 1400, the average vinyl copolymer chloride of particle size 1 [mu] m PVC · PVAc Copolymer (4) A vinyl chloride copolymer surface-treated calcium carbonate ( 5.5% by weight containing vinyl acetate obtained by an emulsion polymerization method ) having an average degree of polymerization of 1800 and having a particle size distribution of two peaks shown in FIG. 3 ( 5) calcium carbonate surface-treated with rosin acid plasticizer phthalate dialkyl (6) DINP polyester (7) a molecular weight 500-600 Kill benzyl phthalate epoxy (8) glycidyl ether type epoxy resin and glycidyl ether obtained by reacting adipic acid of hydrogenated bisphenol A ester epoxy resin adhesion imparting agent (9) trimerization blocked isocyanate resin fluidity modifier ( 10) Vinyl chloride resin having a degree of polymerization of 600 to 700 and an average particle size of 1 μm dissolved in 200 wt% of DINP in advance Additive (11) Zn-based stabilizer, calcium oxide hydrocarbon solvent (12) Olefin-based hydrocarbon mixture (Average molecular weight: 177)

[0031]

As described above, the sealing material composition of the present invention is suitable for coating with a slit type nozzle, has little change in coating bead width due to temperature and coating distance, and has good bead surface smoothness, Moreover, it has a good gap filling property, is suitable for application by a robot, and is convenient for automatic application.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a state in which a sealing material is applied to a gap between members to be applied.

FIG. 2 is a cross-sectional view showing a state in which a sealing material has penetrated when being applied to a gap of a member to be coated in FIG.

FIG. 3 is a graph showing a particle size distribution of a vinyl chloride resin having two particle size distribution peaks used in Examples.

FIG. 4 is a graph showing the shear rate history of the compositions of Examples.

5 is a graph showing the shear rate history of the composition of Comparative Example 2. FIG.

FIG. 6 is a graph showing the shear rate history of the composition of Comparative Example 4.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Haruji Shibata, Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor: Toshiro Miyajima, Toyota Town, Aichi Prefecture, Toyota City, Toyota

Claims (4)

[Claims] 1. A sealant composition comprising a plastisol which a main agent of a vinyl chloride resin, the viscosity ratio of the viscosity of the viscosity and 62sec ^-1 shear rate of 4.2 sec ^-1 at 20 ° C. is 5.5 to 7 And a shear rate of 10 ³
sealant composition viscosity ratio of the viscosity of the viscosity and 10 ⁴ sec ^-1 in sec ^-1 is characterized in that 1.2 to 1.8. 2. The plastisol contains a vinyl chloride resin in an amount of 18 to 28% by weight based on the total weight of the composition, of which 0.7 to 1 is included.
The vinyl chloride resin having a particle size distribution having two peaks of μm and 2.5 to 5 μm is 3 to 15% by weight of the entire composition, and contains a plasticizer, a flow control agent, and a filler. The sealing material composition described. 3. The flow control agent has an average degree of polymerization of 600 to 70.
The sealing material composition according to claim 2, wherein the vinyl chloride resin or chlorinated rubber of No. 0 is dissolved in a plasticizer or a solvent. 4. A surface-treated calcium carbonate as a filler, which is used in an amount of 15 to 20% by weight of the total composition.
The sealing material composition described.