JPH0742373B2 - Plastisol composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plastisol composition most suitable for use as an adhesive, a sealing agent, and a coating agent in various industries including the automobile industry.

[Conventional technology]

Conventionally, in the automobile industry and various other industrial products, undercoating is generally applied and then overcoating is applied.Before applying this overcoating, protection of the base material and undercoating film, sealing and overcoating film Sealing or coating with a plastisol composition as a pretreatment to finish the surface neatly is generally performed, especially an automobile body having a cationic electrodeposition coating applied as an undercoat from the rust-preventive surface. It is essential to seal or coat with a plastisol composition.

In a conventional plastisol composition, a (meth) acrylate-based monomer such as ethylene glycol di (meth) acrylate or trimethylolpropane tri (meth) acrylate is used to improve adhesion to a steel plate or an undercoat film. However, since these are anaerobic, the crosslinking reaction after storage is insufficient, and sufficient adhesion of the plastisol composition to a steel sheet or an undercoat coating film such as a cationic electrodeposition coating film cannot be obtained. Because it is not used much.

For this reason, as a method for improving the adhesiveness of the plastisol composition, for example, a method using an aromatic diisocyanate polymer (isocyanate-containing isocyanurate) (JP-A-57-105441), an isocyanate group containing an oxybenzoic acid ester, a long A method using an aromatic diisocyanate polymer blocked with a chain alkylphenol or the like (JP-A-62-41278, JP-A-62-190267) has been proposed.

[Problems to be Solved by the Invention]

However, the conventional plastisol composition described above,
In order to obtain the desired adhesive strength, a considerably high temperature is required to cleave the block material, for example, a heating temperature of 180 to 220 ° C., and as a means for overcoming this drawback, heat for promoting thermal cleavage of the block agent is used. It has been proposed to include a cleavage accelerator (JP-A-62-41278). Further, recently, a coating film has been applied by the above-mentioned cationic electrodeposition coating (and this coating film has become a thick film), and the adhesiveness of the plastisol composition to such a coating film is still unsatisfactory. It has the problem of being sufficient.

Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional plastisol composition and to firmly bond to a metal surface or a metal coated surface (particularly, a film thickness coated surface by cationic electrodeposition coating) at a relatively low temperature and a short time. It is to provide a plastisol composition which can be adhered.

[Means for Solving the Problems]

The present invention is a plastisol composition containing a vinyl chloride polymer, a plasticizer, an adhesion improver and a thermal cleavage accelerator, wherein the adhesion improver is a dialkylphenol block of an aromatic diisocyanate polymer described later. It is a plastisol composition.

The vinyl chloride-based polymer that can be used in the present invention includes a vinyl chloride homopolymer or copolymer, and the copolymerizable monomer that can form a vinyl chloride copolymer is vinyl acetate or propionic acid. Vinyl, vinyl esters such as vinyl stearate, maleates such as dimethyl maleate and dibutyl maleate, fumarates such as diethyl fumarate and dimethyl fumarate, methyl (meth) acrylate, ethyl (meth) acrylate , 2-hydroxyethyl (meth) acrylate, 2-
(Meth) such as hydroxypropyl (meth) acrylate
Acrylic acid esters, vinyl ethers such as vinyl methyl ether, vinyl butyl ether and the like can be mentioned. As these vinyl chloride polymers and copolymers, usual commercially available vinyl chloride polymers having a polymerization degree of 500 to 2000 can be used. Commercially available vinyl chloride polymers include, for example, Zeon 121 and 37J (trade name, manufactured by Nippon Zeon Co., Ltd.), Kanevinyl PSL-10, PSH-10, PSM-80 and PCH.
-12 (trade name, manufactured by Kanebuchi Chemical Co., Ltd.), Denka Vinyl PA-1000
And ME-180 (trade name, manufactured by Denki Kagaku Co., Ltd.) and the like, and one kind or a mixture of two or more kinds thereof can be used.

The plasticizer that can be used in the present invention is not particularly limited as long as it is a plasticizer generally used for vinyl chloride polymers, and examples thereof include di-n-octyl phthalate (DOP),
Di-2-ethylhexyl phthalate, diisononyl phthalate (DINP), diheptyl phthalate (DHP) and other phthalic acid plasticizers, di-2-ethylhexyl adipate (DOA), azelate, sebacate and other fatty acid ester plasticizers, tricre There are phosphate ester-based plasticizers such as dilyphosphate and epoxy-based plasticizers such as epoxidized soybean oil. These are the stability and curability of the plastisol composition, the hardness of the coating film after firing, the heat resistance and the phase. It can be optionally selected depending on the required performance such as solubility, and can be used in the form of one kind or a mixture of two or more kinds. The amount of the plasticizer used may be appropriately selected and used in consideration of the solid content concentration in the plastisol composition, fluidity, etc., and is generally 30 to 300 parts by weight with respect to 100 parts by weight of the vinyl polymer. Good to use. Further, a part of the above-mentioned plasticizer can be replaced with a paraffinic solvent such as dodecylbenzene or mineral terpene, and it is appropriately selected according to the application.

The plastisol composition according to the present invention contains a dialkylphenol block of an aromatic diisocyanate polymer in order to improve the adhesiveness of the plastisol. The dialkylphenol block product of the aromatic diisocyanate polymer used in the present invention generally has a molecular weight of 900 to 3
Those in the range of 3000 are preferable, and the average molecular weight is 1000 to 1500.
It is desirable to use one in the range of 0.

When the average molecular weight of the dialkylphenol block of the aromatic diisocyanate polymer is less than 1000, when the plastisol composition is applied, sufficient adhesion of the coating film cannot be exhibited, the weather resistance deteriorates, and yellowing of the coating film occurs. It is not preferable because it may cause tightening. On the other hand, when it is more than 15,000, the viscosity of the plastisol composition is remarkably increased and the workability is deteriorated, which is not preferable.

The amount of the dialkylphenol block of the aromatic diisocyanate polymer used in the present invention is 0.5 to 20 parts by weight, preferably 1 to 20 parts by weight with respect to 100 parts by weight of the vinyl chloride polymer.
10 parts by weight is recommended.

Examples of the aromatic diisocyanate (monomer) constituting the aromatic diisocyanate polymer used in the present invention include tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, etc., and these may be used alone or in combination of two kinds. The above may be mixed and used. Further, a part thereof may be substituted and used with an aliphatic diisocyanate such as hexamethylene diisocyanate or an alicyclic diisocyanate such as isophorone diisocyanate.

The aromatic diisocyanate polymer is preferably prepared by polymerizing the diisocyanate compound in the plasticizer used in the desired plastisol composition, and in some cases, in an inert solvent such as butyl acetate. Can be made. At this time, a well-known catalyst such as Mannich base, an alkali metal salt of a fatty acid, a tertiary amine or an alcoholate may be used as a polymerization catalyst (cyanurate-forming catalyst).

According to the present invention, the above-mentioned aromatic diisocyanate polymer uses a dialkylphenol as a blocking agent for its isocyanate group. Examples of the dialkylphenol that can be used include xylenol (dimethylphenol), di-t-butylphenol, and dinonylphenol. These blocking agents may be used in an equivalent ratio to the free isocyanate groups of the aromatic diisocyanate polymer.

The plastisol composition according to the present invention uses the above-mentioned dialkylphenol block of the aromatic diisocyanate polymer described above as an adhesion improver. Therefore, the plastisol composition is applied to a metal surface or an undercoating film surface and then coated. When the film is baked, it is necessary to cleave the dialkylphenol blocking agent, which is generally carried out by heating.
Since it takes a long time, a thermal cleavage accelerator is used.

As the thermal cleavage accelerator that can be used, there are inorganic or organic compounds of alkali metals and other metals. More specific examples thereof include fatty acids, particularly fatty acids having 8 to 10 carbon atoms and 8 carbon atoms, as the alkali metal compounds. ~ 10 alkylsulfates, potassium sulfonates such as alkyl sulfonic acid, sodium salts, as the metal compound other than alkali metal salts, basic lead silicate, lead white, inorganic metal compounds such as zinc white, lauric acid, stearic acid, Organometallic compounds such as cadmium such as naphthenic acid and salicylic acid, barium, zinc, lead and magnesium, and further such as dibutyltin laurate, dioctyltin maleate, tin octenoate, dibutyldibutoxytin and bis (2-ethylhexyl) tin oxide. Mention may be made of tin compounds. These can be used alone or in the form of a mixture of two or more kinds.

The amount of these thermal cleavage accelerators used is not particularly limited and variously varies depending on the type, but generally, it should be used to the extent that storage stability of the plastisol composition is not deteriorated, Usually, 0.05 to 5 parts by weight, preferably 0.2 to 2 parts by weight, is used with respect to 100 parts by weight of the vinyl chloride polymer.

The plastisol composition of the present invention includes, in addition to the above-mentioned components, other optional additives such as a filler, a thickener, a stabilizer,
An adsorbent or the like can be added. For example, as a filler, an inorganic filler such as tal, kaolin, diatomaceous earth, powder rubber, regenerated rubber, an organic filler such as cellulose powder can be used, and as a thickener, bentonite, metal soap, etc. can be used, and metal soap can be used. Can also be used as a stabilizer, for example, zinc stearate, calcium stearate, barium oleate, etc., which are used alone or as a composite stabilizer. As the adsorbent, powders of magnesium oxide, calcium oxide, silicon oxide and the like can be added, especially when the plastisol composition contains water. These optional additives are well known to those skilled in the art.

In producing the plastisol composition of the present invention, the vinyl chloride polymer described above, a plasticizer, an adhesion improver and a thermal cleavage accelerator according to the present invention, and further other additives as required. It can be manufactured by uniformly kneading and defoaming.

When storing the manufactured plastisol composition, it is preferable to put it in a container and seal it under a nitrogen atmosphere.

INDUSTRIAL APPLICABILITY The plastisol composition according to the present invention can be used as a sealing material, a coating material or an adhesive agent for protecting the base material of various industrial products including the automobile industry. Particularly, in the automobile industry, it is used for the purpose of rust prevention, cushioning of flying pebbles during running, pinhole sealing, etc., for car bodies coated with cationic electrodeposition.

The coating amount of the plastisol composition of the present invention can be widely varied depending on the application and is not particularly limited.
Generally, when it is used as an undercoat paint for an overcoat paint containing, for example, an alkyd resin, an epoxy resin, an acrylic resin or the like, it may be applied so that the applied film thickness is 0.5 to 5 mm.

The coating method can be a normal method adapted to the intended use,
For example, pouring, dipping, spraying, brush coating, etc. can all be used. The plastisol composition according to the present invention applied to an object to be coated can be heat-treated at a temperature of 120 to 140 ° C for 15 to 30 minutes to cure the coating film.

[Action]

Since the plastisol composition according to the present invention contains a dialkylphenol block of an aromatic diisocyanate polymer as an adhesion improver, the metal surface or the metal coating surface, particularly the cationic electrodeposition coating surface at a low temperature, for a short time. For example, heat treatment at 120 to 140 ° C. for 15 to 30 minutes enables easy and strong adhesion.

Further, the plastisol composition of the present invention has good storage stability like the conventional plastisol composition, does not have an extreme increase in viscosity even when left for a long time, is easy to handle, and discolors the coating film itself of the plastisol composition or No coloring occurs and the coating film of the topcoat paint does not discolor.

〔Example〕

The present invention will be described below with reference to examples and reference examples.
Character parts and% are parts by weight and% by weight unless otherwise specified.
Is.

Reference Example Production of Dialkylphenol Block of Aromatic Diisocyanate Polymer (Cyanurate) 100 parts of tolylene diisocyanate, 400 parts of dioctyl phthalate in one flask equipped with a stirrer, thermometer and nitrogen inlet tube, potassium caprylate as a cyanurate catalyst 0.6 Prepare the department,
The mixture was heated and stirred under a nitrogen stream at 25 to 60 ° C. and reacted until the isocyanate content reached 3.2% to obtain a tolylene diisocyanate polymer (cyanurate).

Next, 62 parts of xylenol as a blocking agent, 248 parts of dioctyl phthalate and 0.3 part of dibutyltin laurate were added, and a NC of 2260 cm ^-1 was measured by IR at a temperature of 50 to 80 ° C under a nitrogen stream.
The reaction was carried out until the absorption of O groups disappeared to obtain a dioctyl phthalate solution containing 20% of xylenol block of tolylene diisocyanate polymer. This is designated as an adhesion improver A.

Using the above-mentioned production method, dialkylphenol block products B to E of tolylene diisocyanate polymer were prepared using the blocking agents shown in Table 1 below.

Comparative Reference Example A monoalkylphenol block F of a tolylene diisocyanate polymer shown in Table 2 below using the following monoalkylphenol blocking agent according to the production method of the above Reference Example.
I made ~ H.

The conventionally used acrylate-based adhesion improver trimethylolpropane trimethacrylate (trade name Light Ester TMP, manufactured by Kyoeisha Yushi-Kagaku Kogyo Co., Ltd.) is used as the adhesion improver I.

Example 1 Production of plastisol composition 100 parts of vinyl chloride polymer ZEON 37J manufactured by Nippon Zeon Co., Ltd., 130 parts of dioctyl phthalate, 200 parts of calcium carbonate, 5 parts of stabilizer (PbSO ₄ ), 28 parts of the adhesiveness improver A and thermal cleavage. Plastisol composition 1 was produced by kneading 2 parts of accelerator dibutyltin laurate at room temperature for 30 minutes using a kneader and defoaming.

Example 2 Plastisol composition 2 was prepared by repeating Example 1 except that a mixture of 80 parts of Zeon 37J and 20 parts of Zeon 121 was used as the vinyl chloride polymer in Example 1.

Examples 3 to 6 Using the method of Example 1 above, 100 parts of the polyvinyl chloride polymer mixture of Example 2 and the adhesiveness improvers A of Example 1 were replaced with the adhesiveness improvers B to E, respectively. Amounts were used to make Plastisol Compositions 3-6.

Comparative Example 1 In the same manner as in Example 1, the adhesiveness improver A of Example 1 was used.
A plastisol composition comparative example 1 was prepared by using the same amount of the adhesion improver F instead of

Comparative Examples 2 to 5 Plastisol composition Comparative Examples 2 to 2 using the same amount of the adhesiveness improvers F to H in place of the adhesiveness improver A in Example 2
I made 4. In Comparative Example 5, only 5 parts of the adhesion improver I was used.

Test Examples The plastisol composition Examples 1-6 and Comparative Examples 1-
The evaluation of 4 was performed as follows.

(1) Storage stability test of plastisol composition The produced blastisol composition was measured for viscosity at a composition temperature of 20 ° C using a Brutsk Field BH type viscometer,
This was taken as the initial viscosity. Next, the plastisol composition was placed in a glass container and left in a constant temperature bath at 40 ° C. ± 1 ° C. for 7 days, the viscosity was measured in the same manner, and the thickening rate was determined.

(2) Shear strength test Shear strength was measured according to JIS K-6830 (automobile sealing material test method) using a test piece of a steel sheet on which a coating film was formed by cationic electrodeposition coating as an adherend. However, the thickness of the plastisol coating is 0.2 mm and the heat treatment is 120
The test was performed at 30 ° C. for 30 minutes, and the pulling speed was 25 mm / min.

(3) State of sheared surface This was visually determined.

(4) Discoloration test of coating film A steel sheet on which a coating film was formed by cationic electrodeposition coating was used as an adherend, and a coating film of plastisol composition was applied to a thickness of 5 mm and heat-treated at 140 ° C for 10 minutes. After that, a top coat paint (trade name: Super White 326, manufactured by Kansai Paint Co., Ltd.) was applied so as to have a film thickness of 5 μ, and then heat treated at 140 ° C. for 20 minutes as a test piece, which was exposed for 200 hours with a fade odometer. The subsequent discoloration was inspected.

The test results are shown in Table 3.

[Effects of the Invention] From the data of the above-mentioned test examples, it is understood that the plastisol composition according to the present invention exhibits excellent adhesiveness (shear strength) when the coating film is cured at a low temperature of 120 ° C for 30 minutes. In contrast, the conventional plastisol composition showed poor adhesion (shear strength) when the coating film was cured at the same temperature and time.
Therefore, heat treatment at a higher temperature for a longer time is required than in the case of using a conventional plastisol composition.

Claims (1)

[Claims] 1. A plastisol composition containing a vinyl chloride polymer, a plasticizer, an adhesion improver and a thermal cleavage accelerator, wherein the adhesion improver is an aromatic diisocyanate polymer such as xylenol or di-t-butyl. A plastisol composition which is a phenol or dinonylphenol block.