JP4557103B2 - Coating composition for polyolefin resin - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a coating composition used for the purpose of improving adhesion and adhesion when coating the surface of a polyolefin resin molded product such as polypropylene, or when bonding another substrate such as aluminum to a polyolefin resin. Related to things.
[0002]
[Prior art and problems to be solved by the invention]
Polyolefin resins such as polypropylene are excellent in properties and inexpensive, and are therefore used in large quantities in automobile parts and the like. However, unlike synthetic resins having polarity such as polyurethane resin, polyamide resin, acrylic resin, polyester resin, etc., there is a problem that coating and adhesion are difficult because of nonpolarity and crystallinity.
[0003]
Therefore, in order to solve this problem, the adhesion has been improved by activating the surface of the polyolefin resin molded product by plasma treatment or gas flame treatment, but this method has complicated processes. In addition, there are drawbacks such as significant equipment costs and time loss, and variations in the surface treatment effect due to the complexity of the shape of the molded product and the influence of pigments and additives.
[0004]
As a method for coating without such surface treatment (pretreatment), various methods using a primer composition as found in polypropylene bumper coating of automobiles have been proposed (for example, Japanese Patent Publication No. 6-27771).
[0005]
In general, as such a primer composition, a primer composition mainly composed of a chlorinated polyolefin resin obtained by modifying polyolefins with unsaturated carboxylic acid and / or acid anhydride thereof and chlorinating is used ( For example, Japanese Patent Publication No. 1-161414). However, although these chlorinated polyolefin resin compositions are excellent in adhesion, they have problems in weather resistance and heat resistance. For example, dehydrochlorination proceeds in a short time at high temperatures (150 ° C. or higher), and the coating film is colored. Could happen.
[0006]
Further, as conventional non-chlorinated polyolefin resin compositions, those proposed in Japanese Patent Publication Nos. 61-11250 and 62-21027 can be mentioned. It became a state. In addition, the dispersed product is difficult to handle because it loses fluidity during low-temperature storage.
[0007]
The object of the present invention is to solve the problems of the prior art as described above, and there is no coloration of the coating film due to high temperature found in the chlorinated polyolefin resin composition, and the conventional non-chlorinated polyolefin resin composition An object of the present invention is to provide a coating composition that exists in a solution state, not in a dispersed state or a gel state, and does not lose fluidity even when stored at a low temperature.
[0008]
As a result of various investigations, the present inventors have found that an amorphous propylene-butene copolymer having a weight average molecular weight of 30,000 to 50,000 is 0.1 to 10% by weight of an α, β-unsaturated carboxylic acid or a derivative thereof. It has been found that a composition comprising an acid-modified amorphous polyolefin obtained by graft copolymerization and at least one selected from alicyclic hydrocarbons and aromatic hydrocarbons has excellent characteristics. The present invention has been completed.
[0009]
That is, this invention provides the coating composition for polyolefin resin as shown below.
Item 1. Acid-modified amorphous polyolefin obtained by graft copolymerization of α, β-unsaturated carboxylic acid or its derivative with 0.1 to 10% by weight of amorphous propylene-butene copolymer having a weight average molecular weight of 30,000 to 50,000 And a coating composition for polyolefin-based resins comprising at least one selected from alicyclic hydrocarbons and aromatic hydrocarbons.
Item 2. Item 1. The amorphous propylene-butene copolymer has a propylene component of 55 to 80 mol% and a heat of crystal melting based on thermal analysis of a differential scanning calorimeter of 0 to 2 J / g. The coating composition for polyolefin resin as described in 2.
Item 3. Item 3. The polyolefin resin coating composition according to Item 1 or 2, wherein the solid content concentration of the acid-modified amorphous polyolefin is 10 to 50% by weight.
Item 4. Item 4. The polyolefin resin coating composition according to any one of Items 1 to 3, wherein the acid-modified amorphous polyolefin has a solid content concentration of 15 to 30% by weight.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The amorphous propylene-butene copolymer used in the present invention is a binary copolymer of propylene and butene. As butene, 1-butene is preferable. The weight average molecular weight of the amorphous propylene-butene copolymer is 5,000 to 60,000, preferably 10,000 to 50,000. The weight average molecular weight can be measured by GPC (gel permeation chromatography).
[0011]
The proportion of the propylene component in the amorphous propylene-butene copolymer is preferably 55 to 80 mol%, more preferably 60 to 70 mol%. If the proportion of the propylene component is less than 55 mol%, the adhesion to the polyolefin tends to decrease, and if the proportion of the propylene component exceeds 80 mol%, the stability of the resulting solution tends to decrease.
[0012]
Moreover, it is preferable that the heat of crystal fusion based on the thermal analysis of a differential scanning calorimeter (DSC) in the amorphous propylene-butene copolymer is 0 to 2 J / g. In this case, the crystallinity of the amorphous propylene-butene copolymer by X-ray diffraction is about 0 to 1%. The amount of heat of crystal melting is more preferably 0 to 1.5 J / g.
[0013]
The α, β-unsaturated carboxylic acid or derivative thereof graft-copolymerized to the amorphous propylene-butene copolymer is an acid anhydride of α, β-unsaturated carboxylic acid in addition to α, β-unsaturated carboxylic acid. Such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid and the like, unsaturated carboxylic acids such as maleic anhydride, itaconic anhydride, citraconic anhydride, etc. Examples thereof include unsaturated carboxylic acid esters such as carboxylic acid anhydride, methyl acrylate, methyl methacrylate, and dimethyl maleate. Of these, maleic acid, itaconic acid and acid anhydrides thereof are preferred. The amount of graft copolymerization is 0.1 to 10% by weight, preferably 1 to 5% by weight, and more preferably 1 to 3% by weight.
[0014]
Graft copolymerization is carried out by a known method. For example, an organic peroxide is added to a molten mixture of the amorphous propylene-butene copolymer and the unsaturated carboxylic acid component or to a mixture solution using a solvent such as toluene or xylene. The graft copolymer is preferably avoided from mixing with air or oxygen, and is preferably carried out in an inert gas atmosphere such as nitrogen gas. Examples of the organic peroxide include acetylcyclohexylsulfonyl peroxide, benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, lauroyl peroxide and the like.
[0015]
The polyolefin resin coating composition of the present invention comprises the acid-modified amorphous polyolefin obtained as described above and at least one selected from alicyclic hydrocarbons and aromatic hydrocarbons. .
[0016]
Examples of the alicyclic hydrocarbon used as a solvent in the coating composition of the present invention include cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, ethylcyclohexane, dimethylcyclohexane, methylethylcyclohexane, and the like. Examples thereof include benzene, toluene, xylene, ethylbenzene, isopropylbenzene, and aromatic solvent naphtha. In addition, ester solvents such as ethyl acetate and butyl acetate, and ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone may be used in combination.
[0017]
The solid content concentration of the acid-modified amorphous polyolefin in the coating composition of the present invention is preferably 10 to 50% by weight, more preferably 15 to 30% by weight from the viewpoints of solubility and handleability. preferable. In the case of such a solid content concentration, the coating composition of the present invention can be in the form of a solution. In particular, when the solid content concentration is 30% by weight or less, the solution state can be kept stable even at a low temperature of 5 ° C. or less.
[0018]
The coating composition of the present invention can be used by adding and mixing pigments. As the pigment, inorganic pigments such as carbon black, titanium dioxide, talc, zinc white, and aluminum paste, and organic pigments such as azo can be used.
[0019]
【The invention's effect】
The coating composition for polyolefin resin of the present invention exists in a solution state and does not lose fluidity even when stored at a low temperature. In addition, since the acid-modified amorphous polyolefin used in the present invention has improved solubility in an organic solvent, the solid content concentration of the resin in the coating composition can be increased and can be developed into a high solid paint.
[0020]
Like the conventional chlorinated polyolefin resin composition, the coating composition for polyolefin resin of the present invention is excellent in adhesion to polyolefin and also exhibits good adhesion to polar paint resins. Moreover, the coating composition for polyolefin resin of the present invention does not color the coating film due to high temperature.
[0021]
【Example】
EXAMPLES Next, although an Example demonstrates this invention in detail, this invention is not limited to this.
[0022]
Production Example 1
In a 1000 ml autoclave, amorphous propylene-butene (propylene component 70 mol%, 1-butene component 30 mol%, weight average molecular weight 30000, heat of crystal melting 1.4 J / g based on thermal analysis of differential scanning calorimeter, 200 parts by weight of X-ray diffraction crystallinity 0%) was dissolved in 500 parts by weight of a mixed solvent of purified toluene and acetone (acetone 5% by weight), and 50 parts by weight of industrial maleic anhydride was added. After heating to ° C., it was dissolved for 1 hour and 5 parts by weight of industrial di-t-butyl peroxide was added. Stirring was continued for 5 hours while maintaining the temperature, and then cooled to room temperature. The obtained resin solution was added to 3000 parts by weight of acetone as a reprecipitation solvent, and the precipitated resin was subjected to suction filtration. After drying, the maleic anhydride modification rate (graft copolymerization amount) of the obtained acid-modified amorphous resin was 1.5% by weight.
[0023]
Production Example 2
An acid-modified amorphous resin was obtained in the same manner as in Production Example 1 using the same amorphous propylene-butene copolymer as used in Production Example 1 except that the weight average molecular weight was 50000. The maleic anhydride modification rate (graft copolymerization amount) of the obtained resin was 1.0% by weight.
[0024]
Comparative production example 1
Crystalline propylene-butene copolymer (76 mol% of propylene component, 24 mol% of 1-butene component, weight average molecular weight of 12500, instead of amorphous propylene-butene copolymer, based on thermal analysis of differential scanning calorimeter An acid-modified resin was obtained in the same manner as in Production Example 1 except that the heat of crystal fusion 21 J / g and the crystallinity 25% by X-ray diffraction were used. The maleic anhydride modification rate (graft copolymerization amount) of the obtained resin was 3.5% by weight.
[0025]
Comparative production example 2
Crystalline propylene-butene copolymer (76 mol% of propylene component, 24 mol% of 1-butene component, weight average molecular weight 35000, instead of amorphous propylene-butene copolymer, based on thermal analysis of differential scanning calorimeter An acid-modified resin was obtained in the same manner as in Production Example 1 except that the heat of crystal fusion was 28 J / g and the crystallinity was 35% by X-ray diffraction. The maleic anhydride modification rate (graft copolymerization amount) of the obtained resin was 1.5% by weight.
[0026]
Example 1
The maleic anhydride-modified amorphous propylene-butene copolymer obtained in Production Example 1 was dissolved in purified toluene to prepare a resin solution having a solid content concentration of 50% by weight. The resin solution flowed uniformly at 23 ° C.
[0027]
Example 2
The maleic anhydride-modified amorphous propylene-butene copolymer obtained in Production Example 1 was dissolved in purified xylene to prepare a resin solution having a solid concentration of 40% by weight. The resin solution flowed uniformly at 23 ° C.
[0028]
Example 3
The maleic anhydride-modified amorphous propylene-butene copolymer obtained in Production Example 1 was dissolved in purified cyclohexane to prepare a resin solution having a solid content concentration of 30% by weight. The resin solution flowed uniformly at 23 ° C.
[0029]
Example 4
The maleic anhydride-modified amorphous propylene-butene copolymer obtained in Production Example 2 was dissolved in purified toluene to prepare a resin solution having a solid content concentration of 30% by weight. The resin solution flowed uniformly at 23 ° C.
[0030]
Example 5
The maleic anhydride-modified amorphous propylene-butene copolymer obtained in Production Example 1 was dissolved in purified toluene to prepare a resin solution having a solid content concentration of 20% by weight.
[0031]
Example 6
The maleic anhydride-modified amorphous propylene-butene copolymer obtained in Production Example 1 is dissolved in a mixed solvent of purified toluene and cyclohexane (mixing weight ratio 64:16), and a resin solution having a solid content concentration of 20% by weight is obtained. Prepared.
[0032]
Example 7
The maleic anhydride-modified amorphous propylene-butene copolymer obtained in Production Example 1 is dissolved in a mixed solvent of purified toluene and cyclohexane (mixing weight ratio 40:40), and a resin solution having a solid content concentration of 20% by weight is obtained. Prepared.
[0033]
Example 8
The maleic anhydride-modified amorphous propylene-butene copolymer obtained in Production Example 1 is dissolved in a mixed solvent of purified toluene and cyclohexane (mixing weight ratio 16:64), and a resin solution having a solid content concentration of 20% by weight is obtained. Prepared.
[0034]
Example 9
The maleic anhydride-modified amorphous propylene-butene copolymer obtained in Production Example 1 was dissolved in purified cyclohexane to prepare a resin solution having a solid concentration of 20% by weight.
[0035]
Example 10
The maleic anhydride-modified amorphous propylene-butene copolymer obtained in Production Example 2 was dissolved in purified ethylcyclohexane to prepare a resin solution having a solid concentration of 20% by weight.
[0036]
Example 11
The maleic anhydride-modified amorphous propylene-butene copolymer obtained in Production Example 2 is dissolved in a mixed solvent of purified toluene and butyl acetate (mixing weight ratio 75: 5), and a resin solution having a solid content concentration of 20% by weight is obtained. Was prepared.
[0037]
The solution stability of the resin solutions obtained in Examples 5 to 11 was measured by the following method.
[Solution stability]
After storing each solution at 23 ° C. for 30 days, the fluidity of the solution was confirmed.
[Solution stability at low temperatures]
After storing each solution at 5 ° C. and −5 ° C. for 10 days, the fluidity of the solution was confirmed.
[0038]
The resin solutions obtained in Examples 5 to 11 flowed uniformly in all cases of 23 ° C, 5 ° C, and -5 ° C.
[0039]
Comparative Example 1
The maleic anhydride-modified crystalline propylene-butene copolymer obtained in Comparative Production Example 1 was mixed with purified toluene so that the solid content concentration was 20% by weight, but was not completely dissolved.
[0040]
Comparative Example 2
The maleic anhydride-modified crystalline propylene-butene copolymer obtained in Comparative Production Example 1 was mixed with purified cyclohexane so that the solid concentration was 20% by weight, but was not completely dissolved.
[0041]
Comparative Example 3
The maleic anhydride-modified crystalline propylene-butene copolymer obtained in Comparative Production Example 2 was mixed with purified toluene so that the solid content concentration was 20% by weight, but was not completely dissolved.
[0042]
Test example 1
The maleic anhydride-modified amorphous propylene-butene copolymer obtained in Production Example 1 was dissolved in purified toluene to prepare a resin solution having a solid content concentration of 20% by weight. The following properties were evaluated for this resin solution.
[Interlayer adhesion]
A 20% by weight toluene solution was applied to a polypropylene plate with a bar coater, dried at 80 ° C. for 10 minutes, and then a urethane paint for repairing plastic (made by Kansai Paint Co., Ltd., trade name: Retan PG80III, 2 parts) on the coated surface. Type urethane paint) was applied and baked at 80 ° C. for 40 minutes to produce a coated piece. The coated surface of this coated piece was cut with a cutter to make 100 grids that reached the substrate at 1 mm intervals, and a cellophane adhesive tape was stuck on it and peeled 10 times in the 180 ° direction. The case where there was no change even after peeling 10 times was taken as 10 points.
[Hot water resistance]
A coated piece was prepared in the same manner as described above, and the coated piece was immersed in warm water at 40 ° C. and allowed to stand for 10 days, then pulled up from the warm water, and the appearance of the coating film surface and interlayer adhesion were confirmed. About the external appearance of the coating-film surface, the presence or absence of blister (swelling of a coating-film) was confirmed, and interlayer adhesiveness was confirmed similarly to the above.
[Gasoline resistance]
A coated piece was prepared in the same manner as described above, and the time (minute) until the wrinkle was formed on the surface of the coating film was confirmed by immersing the coated piece in regular gasoline at 20 ° C. Finished in up to 120 minutes.
[0043]
As for the evaluation results, the interlayer adhesion was 10 points when not immersed in warm water and when immersed. No blisters were observed after warm water immersion. In addition, no wrinkle was found after 120 minutes of immersion in gasoline.
[0044]
For reference, a chlorinated polypropylene resin solution was prepared, and various characteristics were evaluated in the same manner as described above, and the same results as above were obtained.

Claims (4)

Acid-modified amorphous polyolefin obtained by graft copolymerization of α, β-unsaturated carboxylic acid or its derivative with 0.1 to 10% by weight of amorphous propylene-butene copolymer having a weight average molecular weight of 30,000 to 50,000 And a coating composition for polyolefin-based resins comprising at least one selected from alicyclic hydrocarbons and aromatic hydrocarbons. The amorphous propylene-butene copolymer has a propylene component of 55 to 80 mol% and a heat of crystal fusion based on thermal analysis of a differential scanning calorimeter of 0 to 2 J / g. The coating composition for polyolefin resin according to 1. The coating composition for polyolefin resin according to claim 1 or 2, wherein the solid content concentration of the acid-modified amorphous polyolefin is 10 to 50% by weight. 4. The polyolefin resin coating composition according to claim 1, wherein the solid content concentration of the acid-modified amorphous polyolefin is 15 to 30% by weight.