JPH02170848A - Rubber based microgel dispersion, production thereof and coating composition containing the same - Google Patents

Abstract

PURPOSE:To obtain a rubber based microgel dispersed material capable of improving fluidity and coating film characteristics, etc., of a coating composition in adding to the coating composition by subjecting a specific tercopolymer rubber to graft polymerization with a metal-containing (meth)acrylate in a specific organic solvent. CONSTITUTION:The rubber based microgel dispersed material obtained by dispersing 10-70 pts.wt. metal-containing (meth)acrylate (preferably zinc diacrylate) into (A) 100 pts.wt. tercopolymer rubber of ethylene with other alpha-olefin and diene based compound, having 50000-200000 number-average molecular weight and being 5-20wt.% in content of diene based compound unit in the presence of an organic peroxide and subjecting the dispersed material to graft polymerization in an organic solvent having 8-10, preferably 8.5-9.5 solubility parameter value while mechanically stirring and containing the organic solvent and microgel particles having <=10mum average particle size.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a novel rubber-based microgel dispersion, a method for producing the same, and a coating composition containing this dispersion. More specifically, the present invention contains microgel particles obtained by graft polymerizing a metal-containing acrylate or a metal-containing methacrylate to a ternary conjugate rubber of ethylene, another α-olefin, and a diene compound. A rubber-based microgel dispersion comprising a rubber-based microgel dispersion, a method for efficiently producing this microgel dispersion, and a paint containing the microgel dispersion with improved physical properties such as fluidity, chipping resistance, impact resistance, and hardness of the coating film. The present invention relates to a composition.

[Prior Art] Conventionally, microgels made of high molecular weight polymers have been used for the purpose of making paints highly solid and improving their fluidity.

However, in conventional microgels made of high molecular weight polymers, surfactants are usually added during production to make them into fine particles, so when these microgels are used in paints, the remaining surfactants will cause the coating to become fine. The drawback was that the performance of the membrane inevitably deteriorated. Therefore, attempts have been made to remove this surfactant, but in that case, the removal is not easy and requires complicated operations, resulting in a significant decrease in productivity. There is a problem with glaring.

On the other hand, chipping-resistant paints are often used in the coating of automobiles to prevent paint film scratches (chipping) caused by small stones that often occur on automobiles traveling on highways.
Many of the conventional chipping-resistant paints have a soft coating film that does not sufficiently meet the hardness required for the coating film.

[Problems to be Solved by the Invention] Under these circumstances, the present invention makes it possible to increase the solidity of the paint and improve its fluidity by adding it to the paint, and also improves the film performance, especially the resistance. A novel microgel dispersion that improves impact properties, chipping resistance, and hardness, a method for efficiently producing the same without using surfactants, and flowability and impact resistance of coating films containing the microgel dispersion The purpose of this invention is to provide a coating composition with improved physical properties such as hardness, chipping resistance, and hardness.

[Means for Solving the Problems] As a result of extensive research to achieve the above object, the present inventors have discovered that metal-containing acrylates and metal-containing methacrylates are dissolved in terpolymer rubber having a specific structure. We have discovered that a desired microgel dispersion can be obtained by carrying out graft polymerization using a specific method in an organic solvent with physical parameters within a specific range, and that the objective can be achieved.
The present invention was completed based on this knowledge.

That is, the present invention provides (A) an organic solvent, and (B) ethylene, other a-olefins, and diene compounds having a number average molecular weight of 50,000 and a diene compound unit content of 5 to 20% by weight. Contains microgel particles with an average particle diameter of 10 μm or less obtained by graft polymerizing 10 to 70 parts by weight of metal-containing acrylate and/or metal-containing methacrylate to 100 parts by weight of ternary coelectric rubber with the compound. A rubber-based microgel dispersion consisting of
The present invention also provides a coating composition containing the rubber-based microgel dispersion in an amount of 1 to 10% by weight in terms of microgel, based on the total weight of the composition.

According to the present invention, the rubber-based microgel dispersion has a number average molecular weight of 50,000 and a diene compound unit content of 5 to 20% by weight of ethylene, other a-olefins, and diene compounds. 10 to 70 parts by weight of metal-containing acrylate and/or metal-containing methacrylate are dispersed in 100 parts by weight of the terpolymer rubber, in the presence of an organic peroxide, and then this dispersion is It can be produced by polymerization under mechanical stirring in an organic solvent having a parameter value of 8 to 10.

I can do it.

The present invention will be explained in detail below.

The terpolymer rubber of ethylene, other a-olefins, and diene compounds used in the present invention has a number average molecular weight in the range of so, o o to 200.000, and has diene compound units. It is necessary that the content be in the range of 5 to 20% by weight. If the number average molecular weight is less than so or ooo, the effect of improving the impact resistance of the coating film will not be sufficiently exhibited, and if it exceeds 200,000, the solubility in solvents will decrease, resulting in larger microgel particles. , the smoothness of the coating film tends to decrease. Further, if the content of the diene compound unit is less than 5% by weight, the addition reactivity of the metal-containing monomer may deteriorate, and if it exceeds 20% by weight, the smoothness of the coating film will be impaired.

Saraban-1 The terpolymer rubber preferably has a solubility parameter (hereinafter referred to as SP value) in the range of 7 to 8. This solubility parameter was determined by Small's method [[Journal of Applied Chemistry (J, Ap l 1. Chem,) J Vol. 31, No. 71
Page (1953)].

Examples of the a-olefin other than ethylene, which is one of the seven polymers of the terpolymer rubber, include evapropylene, butene-1, pentene-1, hexene-1, heptene-1
, octene-11nonene-11decene-1,4-methylpentene-1,4-methylhexene-1,4,4-dimethylpentene-1, etc. Alternatively, two or more types may be used in combination.

On the other hand, examples of diene compounds that are other monomers of the terpolymer rubber include butadiene, isoprene,
．． Examples include 3-pentadiene, 1,4-hexadiene, cyclopentadiene, cyclooctadiene, and ethylidene norbornene. Of these, ethylidene norbornene is preferred because of its good weather resistance. One type of these diene compounds may be used, or two or more types may be used in combination.

Examples of the metal-containing acrylate and metal-containing methacrylate used in the present invention include zinc acrylate, zinc methacrylate, aluminum acrylate,
Examples include aluminum methacrylate, calcium diacrylate, calcium dimethacrylate, etc.
Among these, zinc diacrylate is particularly preferred from the viewpoint of solubility in solvents, polymerizability, and compatibility of the resulting microgel particles with paints. Further, one type of the metal-containing upwind knob may be used, or two or more types may be used in combination.

This metal-containing monomer needs to be used in an amount of 10 to 70 parts by weight based on 100 parts by weight of the terpolymer rubber. If this amount is less than 10 parts by weight, the hardness will be insufficient and the desired gel will not be obtained, and if this amount exceeds 70 parts by weight, the elasticity of the two rubbers will be lost, resulting in insufficient elongation of the coating film.

In the present invention, this metal-containing monomer is graft-polymerized onto the terpolymer rubber, and an organic peroxide is used in this case. Examples of the organic peroxide include dicumyl peroxide, di-tert-butyl peroxide, tert-butylperoxy (2-ethylhexanoate), 1,1-bis(tert-butylperoxy)3,3,5-trimethyl Examples include cyclohexane (Barhexa 3M). These organic peroxides are 1
Seeds may be used or two or more types may be used in combination, and the amount used is usually 0.02. -10 milliequivalents, preferably 1 to 10 milliequivalents.

In order to produce the microgel dispersion of the present invention, first, required amounts of the terpolymer rubber and metal-containing upwind rubber are homogeneously dispersed together with a required amount of organic peroxide. In this case, it is advantageous to perform the dispersion using a dispersing machine such as a two-roll or twin-screw Niegoo, and it is also important to perform the dispersion under temperature conditions in which the organic peroxide is stable. If this dispersion is insufficient, the microgel particles ultimately produced will be large, and the object of the present invention will not be achieved.

Next, the dispersion thus obtained has an SP value of 8 to
10, preferably 8.5 to 9.5, in an organic solvent under mechanical stirring. At this time, it is important that the dispersion of the terpolymer rubber and the metal-containing upwind rubber be polymerized in a state in which they are microdispersed in the solvent. The SP value of the solvent is 8
If it is less than 10, the terpolymer rubber will dissolve, but the dispersibility and solubility of the metal-containing upwind rubber will be poor; if it exceeds 10, the dispersibility of the metal-containing upwind rubber will be good, but the ternary copolymer rubber will dissolve. Since the solubility of the polymer rubber deteriorates, it becomes difficult to form microscopic gel particles. Examples of such solvents include mixtures of aromatic hydrocarbons such as toluene and lower alcohols such as isopropyl alcohol.

[The lower the reaction temperature, the smaller the particle size tends to be, but it is preferably selected in the range of 50 to 100°C, taking into account the necessary decomposition temperature of the organic peroxide used. Furthermore, for mechanical stirring, the stirring speed is 2000 rpm/
It is advantageous to use high speed stirring with no rotation.

The microgel particles in the microgel dispersion thus obtained must have an average particle diameter of 10/7 m or less, and if this average particle diameter exceeds 10 μm, the object of the present invention is not sufficiently achieved. Not done.

Further, the content of microgel particles in the microgel dispersion is preferably in the range of 5 to 25% by weight. Therefore, after the completion of polymerization, the solvent is distilled off or added, so that the microgel particles have a desired concentration. You may adjust it so that

In order to improve the dispersion stability of the microgel particles, a coating resin soluble in a solvent can be mixed with the rubber microgel component or dispersion of the present invention. Examples of such resins include polyester resins, unsaturated polyester resins, acrylic resins, melamine resins, and urethane resins. The dispersion stability of microgel particles can be improved by selecting and adding a resin having an appropriate SP value depending on the purpose of use. The amount of these resins used is preferably 100 parts by weight or more per 100 parts by weight of the microgel. Further, there is no particular restriction on the timing of its addition, and it may be added when forming a microgel, or may be added after the formation of a microgel is completed.

The coating composition of the present invention contains the rubber-based microgel dispersion in an amount of 1 to 10% in terms of microgel based on the weight of the composition.
It is contained in a proportion of % by weight. This amount is 1% by weight
If it is less than 10% by weight, the effect of improving physical properties of the coating film such as chipping resistance will not be sufficiently exhibited, and if it exceeds 10% by weight, the appearance properties such as gloss of the coating film will tend to deteriorate.

[Example] Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited in any way by these examples.

Example 1 100 parts by weight of EPDM [ethylene propylene terpolymer manufactured by Japan Synthetic Rubber Co., Ltd., JSREP33],
Zinc acrylate [manufactured by Asada Chemical Industry Co., Ltd., #R5
10 parts by weight of Sco 501i and 3.5 parts by weight of Barhexa 3M [1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, manufactured by NOF Corporation] in two rolls. The EPDM blend was prepared by kneading for a minute.

Next, 22321111 parts of toluene and 118 parts by weight of inpropyl alcohol were placed in a 4-hole flask equipped with a stirrer (TK Homomixer), and the mixture was rotated at 2000 rpm.
In this solvent, while stirring at a rotational speed, the EPD described above is added.
M formulation was added over a period of 8 hours at room temperature, followed by 250 g of a 50% by weight xylene solution of an oil-free polyester resin obtained from isophthalic acid, adipic acid, neopentyl glycol and trimethylolpropane, The temperature was maintained at 80° C. and stirring was continued for an additional 20 hours. After the reaction is complete, the system is slightly depressurized and the solvent 17519
was distilled off to obtain the desired microgel dispersion 10009.

The properties of this microgel dispersion are shown in Table 1.

Examples 2 to 5, Comparative Example 1.2 A microgel dispersion was prepared in the same manner as in Example 1 using each component in the proportions shown in Table 1. The properties of this microgel dispersion are shown in the table.

(Left below) Examples 6 to 10 Using the microgel dispersions obtained in Examples 1 to 5, the second
Intermediate coatings were prepared by dispersing microgels with the formulation shown in the table.

Next, the above intermediate coating paint was applied to a zinc phosphate-treated mild steel plate having a thickness of 0.8 ram so that the dry film thickness was 60 μm, and baked at 150° C. for 30 minutes. The evaluation value of the chipping resistance of the coating film of this panel by a gravelometer,
The results of the impact resistance test and the pencil hardness are shown in Table 2.

(Left below) 1) Butyl alcohol solution of 1500.50% by weight Mn.

2) Same as polyester resin solution A in Table 1.

3) Unsaturated polyester resin obtained from maleic acid, phthalic acid, and propylene glycol, Mn 2500, acid value 5, hydroxyl value 100.50% by weight styrene solution.

4) Methyl ethyl ketone peroxide 55% by weight dimethyl phthalate solution.

5) Using a gravelometer [manufactured by Suga Test Instruments Co., Ltd.],
ISA-500179 Crushed stone 509 was sprayed at an angle of 90'' and air pressure was 4 kg/c.
The degree of scratches on the paint film was evaluated on a scale of 1 to 1O, with a score of 10 for damage to the paint film.

A rating of 6 or higher is considered good.

6) Using an impact tester (1/2 inch diameter, 500g, 50cm) according to JISK-54006, 13, 3B method,
The test was conducted at 20°C. Those in which no cracks occurred in the coating film at 50 cm were deemed to have passed.

7) Cold rolled steel plate (300 x 10
0 x 0.8 mm) was fixed vertically, and the paint was diluted with xylene at 20 ℃ for 20 seconds at 7 Ord Cup No. 4 so that the dry film thickness was zero at the top of the plate and 100 μm at the bottom. The film thickness was continuously changed so that
After heating and drying for a minute, observe whether there is any sagging on the painted surface.
The maximum film thickness without any formation was determined.

Comparative Example 3 Example 6 except that no microgel dispersion was used.
An intermediate coating was prepared in the same manner as in steps 1 to 10, and a panel was created. Table 2 shows the physical properties of the panel coating.

As can be seen from these results, in Comparative Examples 1 and 2, in which the content of metal-containing monomers was outside the range of the present invention, the desired stable microgel dispersions could not be obtained.

On the other hand, in Examples 1 to 5 according to the present invention, desired microgel dispersions were obtained.

Moreover, the paint of Comparative Example 3, which does not contain microgel, has low coating film hardness and chipping evaluation value, but the paints of Examples 6 to 10 according to the present invention have good chipping evaluation value, good impact resistance, The pencil hardness also showed good results, exceeding HB.

[Effects of the Invention] The rubber-based microgel dispersion of the present invention contains microgel particles in a homogeneous dispersed state, which are obtained by graft-polymerizing a specific metal-containing upwind polymer onto a specific terpolymer rubber. Due to the elasticity of the terpolymer rubber, it is suitably used in paint systems as an additive that provides physical properties that combine impact energy absorption at low temperatures and sufficient hardness due to metal ion crosslinking at high temperatures.

Furthermore, the coating composition of the present invention containing the microgel particles has good fluidity and also has sufficiently satisfactory properties in terms of impact resistance, chipping resistance, and hardness of the coating film.

Claims (1)

[Scope of Claims] 1 (A) an organic solvent, and (B) a number average molecular weight of 50.0
Metallic acrylate and A rubber-based microgel dispersion containing microgel particles having an average particle diameter of 10 μm or less obtained by graft polymerizing 10 to 70 parts by weight of/or metal-containing methacrylate. 2 The number average molecular weight is 50,000 to 200,000,
and 10 parts by weight of a terpolymer rubber of ethylene, another α-olefin, and a diene compound with a diene compound unit content of 5 to 20% by weight, and 10 parts by weight of metal-containing acrylate and/or metal-containing methacrylate. ~70 parts by weight,
Claim 1, characterized in that the dispersion is dispersed in the presence of an organic peroxide and the dispersion is then polymerized in an organic solvent with a solubility parameter value of 8 to 10 under mechanical stirring.
The method for producing the rubber-based microgel dispersion described above. 3. A coating composition comprising 1 to 10% by weight of the rubber-based microgel dispersion according to claim 1 in terms of microgel, based on the total weight of the composition.