JP3538836B2 - Aqueous dispersion and its use - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a primer and a paint used for painting a polypropylene resin molded product,
The present invention relates to an aqueous dispersion suitable for applications such as a primer and an adhesive when bonding a polypropylene resin product to another substrate.

[0002]

2. Description of the Related Art Conventionally, olefin resins such as polypropylene are used in automobile parts because of their high chemical stability, low cost, excellent balance of physical properties, and recyclability. The number of products is increasing year by year mainly in household appliances and molded products for household goods. However, since the olefin-based resin does not contain a polar group in the molecular chain, it has a drawback that it is difficult to be applied and that adhesion and the like are difficult. For this reason, in the case of a polypropylene-based coating or bonding, it is common to use a resin containing chlorinated polypropylene as a main component as a primer or one coat. However, chlorinated polypropylene generally uses an aromatic organic solvent such as toluene and xylene, and has a problem in terms of safety and health and environmental pollution.

[0003] In recent years, due to these environmental problems, the use of water has been actively studied, and attempts have been made to produce an aqueous dispersion of chlorinated polypropylene (Japanese Patent Publication No. 8-6009, Patent 2727).
032, Patent No. 2603173).

[0004] In particular, in automotive interior applications, not only adhesiveness but also heat resistance is required. However, the aqueous resin dispersion of chlorinated polypropylene alone has good adhesion to polypropylene but has a problem in heat resistance.

[0005]

DISCLOSURE OF THE INVENTION The present invention has excellent adhesiveness, coating appearance, solvent resistance, and heat resistance for use as a paint, ink or adhesive for molding or film of a polyolefin resin. And an aqueous dispersion giving a good coating film.

[0006]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have made intensive studies and found that (A) chlorine content
A carboxylic acid-modified chlorinated polyolefin of 15 to 35% by weight, and (B) a number average molecular weight of 4000
It has been found that this can be achieved by an aqueous dispersion mainly composed of a resin mixed with a chlorinated polyolefin having a chlorine content of 0 to 70,000 and a chlorine content of 20 to 40% by weight.

That is, (A) a carboxylic acid-modified chlorinated polyolefin having a chlorine content of 15 to 35% by weight, and (B) a number average molecular weight of 40000 to 700 which is a heat-resistance-imparting component.
The mixing ratio (A) / (B) with chlorinated polypropylene having a chlorinated polypropylene content of 20 to 40% by weight is a weight ratio.
In this method, a mixed resin having a ratio of 80/20 to 40/60 is melted using a melting aid, then neutralized with a basic substance, and dispersed in water using a nonionic surfactant.

[0008] The aqueous dispersion is used as a primer or a paint for coating a molded product of a polyolefin resin, or as a primer or adhesive for bonding a polypropylene resin molded product to another substrate. It was found that a coating film having good heat resistance and good coating appearance was provided.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The aqueous dispersion of the present invention comprises (A) a carboxylic acid-modified chlorinated polyolefin having a chlorine content of 15 to 35% by weight, and (B) a chlorine-containing polyolefin having a number average molecular weight of 40,000 to 70,000. The main component is a mixed resin of a chlorinated polyolefin having a content of 20 to 40% by weight. This will be described in detail below.

(A) The carboxylic acid-modified chlorinated polyolefin is obtained by dissolving the polyolefin in a solvent inert to chlorine, such as chloroform, and blowing it with chlorine gas to chlorinate it. Carboxyl groups can be introduced by graft copolymerization of carboxylic acids or anhydrides thereof.

The polyolefin is a homopolymer of ethylene or propylene, or ethylene or propylene and other comonomers such as butene-1, pentene-1, hexene-1, butene-1, heptene-1, octene-1 and the like. Α- having 2 or more carbon atoms, preferably 2 to 6 carbon atoms
It is a random copolymer or a block copolymer of an olefin comonomer, and a random copolymer is preferable to a block copolymer. Further, two or more comonomers may be copolymerized.

(A) The chlorine content of the carboxylic acid-modified chlorinated polyolefin is 15 to 35% by weight, and if it is less than 15% by weight, the melting point and the melt viscosity are too high to disperse well in water. If it exceeds 35% by weight, the adhesion to the substrate becomes poor. Preferably it is 18 to 28% by weight.

The carboxylic acid-modified polyolefin is
A polyolefin obtained by modifying the polyolefin with an α, β-unsaturated carboxylic acid or an anhydride thereof by a graft reaction. Examples of the α, β-unsaturated carboxylic acid or anhydride thereof include maleic acid, fumaric acid, itaconic acid, citraconic acid, allylsuccinic acid, mesaconic acid, aconitic acid, and acid anhydrides thereof. In addition, esters of these carboxylic acids are also included. Of these,
Acid anhydrides are preferred. The method of graft copolymerizing an α, β-unsaturated carboxylic acid or an anhydride thereof with a polyolefin may be a known method. For example, it is preferable to carry out the method by heating and melting a polyolefin above its melting point and graft-copolymerizing in the presence of a radical generator.

(A) The acid value of the carboxylic acid-modified chlorinated polyolefin is preferably from 10 to 100. If the acid value is less than 10, the adhesion to polar materials is poor. If the acid value exceeds 100, the adhesion to polypropylene is poor. Become inferior.

The number average molecular weight of (A) the carboxylic acid-modified chlorinated polyolefin is preferably from 2,000 to 40,000. If it is less than 2,000, the cohesive force is insufficient, and the adhesion to the polyolefin resin becomes poor. This is not preferable because the operability at the time of making it deteriorate. In order to keep the molecular weight within this range, it is possible to select the molecular weight of the raw material and the conditions for performing the graft reaction, and it is also possible to perform the graft reaction after once lowering the molecular weight of the raw material. . The number average molecular weight can be measured by GPC (gel permeation chromatography).

On the other hand, the chlorinated polyolefin (B) which is a heat-resistance-imparting component can be produced by a known method in the same manner as described above.

(B) The number average molecular weight of the chlorinated polyolefin component is from 40,000 to 70,000. If it is less than 40,000, the heat resistance is insufficient, and if it exceeds 70,000, it is difficult to melt, so that it is difficult to produce.

(B) The chlorine content of the chlorinated polyolefin is from 20 to 40% by weight, and if it is less than 20% by weight, the melt viscosity is too high to disperse well in water. If it exceeds 40% by weight, the adhesion to the substrate is poor. Preferably 25-35 weight
%.

In the present invention, the component (A) and the component (B)
The mixing ratio of the components is preferably 80/20 to 40/60 by weight.
If the component (B) is less than 20% by weight, heat resistance is insufficient, and if it exceeds 60% by weight, an aqueous dispersion cannot be obtained.

As a melting aid for mixing the components (A) and (B), aromatic solvents such as toluene and xylene are desirable, and the amount thereof used is determined by mixing the components (A) and (B). It is preferably from 40 to 80% by weight, particularly preferably from 50 to 60% by weight, based on the resin. If the amount of the above-mentioned melting aid is less than 40% by weight, it is difficult to produce because it is difficult to melt, and if it exceeds 80% by weight, the use amount of the surfactant is relatively increased, and the adhesion and heat resistance are inferior. .

The nonionic surfactant used in the present invention includes polyoxyethylene alkyl ester, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenol ether, sorbitan alkyl ester,
Examples thereof include polyoxyalkylene alkyl ethers. The nonionic surfactant may be used by mixing two kinds having different HLB. In addition, a small amount of an anionic surfactant may be used in combination mainly with a nonionic surfactant. The amount of the nonionic surfactant is preferably from 1 to 30% by weight, more preferably from 3 to 25% by weight, based on the mixed resin of the components (A) and (B).
% By weight is desirable. If the amount is less than 1% by weight, the stability of the aqueous dispersion becomes poor, and if it exceeds 30% by weight, the adhesion and water resistance of the coating film become poor.

In the present invention, the basic substance is added
This is for neutralizing the carboxyl groups and ionizing them to improve the dispersion in water. Unless a basic substance is added, a stable dispersion cannot be obtained. As the basic substance, sodium hydroxide, potassium hydroxide, ammonia, methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, ethanolamine, propanolamine, diethanolamine, N-methyldiethanolamine, dimethylamine, triethylamine, Examples include morpholine. The amount of the basic substance is preferably 0.4 to 1.5 chemical equivalents based on the carboxyl group of the component (A) used. If it is less than 0.4 chemical equivalent or exceeds 1.5 chemical equivalents, the stability of the resulting aqueous dispersion is poor.

In the present invention, the aqueous dispersion can be obtained by a known method (for example, the method described in Oil Chemistry, 17, 133 (1968)). For example, the components (A) and (B) are mixed, and an aromatic solvent such as toluene or xylene is added as a melting aid. Then, melt at about 90-120 ° C,
A nonionic surfactant and a basic substance are added and melt-kneaded. In a molten state, water at 80 to 98 ° C. is added, and W / O is added.
A dispersion of the mold is formed, which is then added to water while adding water.
The aqueous dispersion of the present invention can be obtained by inverting the phase to a / W type dispersion and adding an additional amount of water as needed. Incidentally, the concentration of the resin component in the aqueous dispersion,
It is desirable to adjust to 25 to 35% by weight.

Using a twin-screw extruder, the components (A) and (B) are mixed, and a melting aid and a nonionic surfactant are added, followed by melt-kneading, and further adding a basic substance. By adding water and inverting the phase from W / O to O / W, the aqueous dispersion of the present invention can be obtained.

The aqueous dispersion thus obtained has excellent adhesion to polyolefin resins, especially polypropylene, and has good heat resistance of the coating film, small particle size and good stability. The aqueous dispersion of the present invention may be used as it is, or may be used by mixing a pigment, or another aqueous resin may be blended.

The aqueous dispersion of the present invention has excellent adhesion to polyolefin resins, especially polypropylene, and is therefore excellent as a primer, paint or adhesive for painting or bonding. Further, the particle diameter is small and the stability is good. In particular, since the aqueous dispersion of the present invention has good heat resistance, it can be used for automotive interior adhesives requiring heat resistance.

[0027]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.

[Production Example 1] 500 g of isotactic polypropylene having a number average molecular weight of 30,000 was placed in a three-necked flask equipped with a stirrer, a dropping funnel and a condenser for refluxing monomers, and kept constant at 180 ° C. Dissolved completely in the oil bath. After performing nitrogen replacement in the flask for about 10 minutes, 20 g of maleic anhydride was added thereto over about 5 minutes while stirring, and then 2 g of di-t-butyl peroxide was added.
It was dissolved in 10 ml of heptane and charged by a dropping funnel over about 30 minutes. At this time, the inside of the system was kept at 180 ° C., and the reaction was further continued for 1 hour. Then, while reducing the pressure inside the flask with an aspirator, unreacted maleic anhydride was removed over about 30 minutes. Next, about 300 g of this product was put into a reaction vessel, and 5 liters of chloroform was added. After sufficiently dissolving under a pressure of ² kg / cm ² , while irradiating ultraviolet rays, the chlorine content was reduced to 22% by weight. Gaseous chlorine was blown from the bottom of the reaction vessel so as to be assured. After completion of the reaction, chloroform as a solvent was distilled off under reduced pressure using a twin-screw extruder to obtain a solid product of carboxylic acid-modified chlorinated polypropylene. Its acid value was 26, melting point was 90 ° C, and number average molecular weight was 28,000. The acid value is J
It was measured according to IS K0070. The number average molecular weight is determined by attaching a column TSK-GEL to Tosoh Corporation HLC-8020, dissolving the component (A) or (B) in THF (tetrahedrofuran), measuring, and measuring from a calibration curve prepared with a polystyrene standard sample. The average molecular weight was determined.

Production Example 2 500 g of an ethylene-propylene copolymer having a number average molecular weight of 30,000 and an ethylene content of 6.1 mol% was mixed with a stirrer, a dropping funnel, and a cooling pipe for refluxing the monomer. Place in flask, 180
Dissolved completely in an oil bath kept constant at ° C. After purging with nitrogen in the flask for about 10 minutes, 33 g of maleic anhydride was graft-copolymerized in the same manner as in Production Example 1 while stirring. Next, about 300 g of this product was charged into the reactor, and gaseous chlorine was blown in from the bottom of the reactor in the same manner as in Production Example 1 so that the chlorine content became 18% by weight. After completion of the reaction, chloroform as a solvent was distilled off under reduced pressure using a twin-screw extruder to obtain a solid product of carboxylic acid-modified chlorinated polypropylene. Its acid value was 62, melting point was 72 ° C, and number average molecular weight was 22,000.

[Production Example 3] 500 g of polypropylene having an MFR of 15 g / 10 min was placed in a three-necked flask equipped with a stirrer, a dropping funnel and a condenser for refluxing monomers, and the oil was kept constant at 180 ° C. Completely dissolved in the bath.
Thereafter, the same operation as in Production Example 1 was performed to reduce the chlorine content to 30% by weight.
Gaseous chlorine was blown from the bottom of the reactor so that After completion of the reaction, chloroform as a solvent was distilled off under reduced pressure using a twin-screw extruder to obtain a solid product of chlorinated polypropylene. This had a melting point of 90 ° C. and a number average molecular weight of 50,000.

Example 1 75 g of the carboxylic acid-modified chlorinated polyolefin (A) obtained in Production Example 1, 25 g of the chlorinated polyolefin (B) obtained in Production Example 3, and 60 g of toluene as a melting aid were equipped with a stirrer. And heated and melted at 100 ° C. Thereafter, 20 g of NS-215 (Nippon Yushi Co., Ltd., nonyl phenyl ether type, HLB 15.0) was added, and the mixture was stirred well and 1.5 g of morpholine was added. Temperature 1
While maintaining the temperature at 00 ° C., water at 90 ° C. was added little by little with vigorous stirring. Although the viscosity increased, the viscosity decreased as water was continuously added. When 200 g of water was added, the contents were taken out to obtain a milky white emulsion.

Example 2 The same operation as in Example 1 was carried out except that the carboxylic acid-modified chlorinated polyolefin (A) obtained in Production Example 1 was changed to 60 g and the chlorinated polyolefin (B) obtained in Production Example 3 was changed to 40 g. To obtain a milky white emulsion.

Example 3 The same operation as in Example 1 was carried out except that the carboxylic acid-modified chlorinated polyolefin (A) obtained in Production Example 1 was 40 g and the chlorinated polyolefin (B) obtained in Production Example 3 was 60 g. To obtain a milky white emulsion.

Example 4 The same operation as in Example 1 was performed except that 70 g of the carboxylic acid-modified chlorinated polyolefin (A) obtained in Production Example 2 and 30 g of the chlorinated polyolefin (B) obtained in Production Example 3 were used. To obtain a milky white emulsion.

Example 5 The same operation as in Example 1 was performed except that 50 g of the carboxylic acid-modified chlorinated polyolefin (A) obtained in Production Example 2 and 50 g of the chlorinated polyolefin (B) obtained in Production Example 3 were used. To obtain a milky white emulsion.

Comparative Example 1 The same operation as in Example 1 was performed using 100 g of the carboxylic acid-modified chlorinated polyolefin (A) obtained in Production Example 1 alone as a resin component to obtain a milky white aqueous dispersion. .

Comparative Example 2 The same operation as in Example 1 was carried out using 100 g of the carboxylic acid-modified chlorinated polyolefin (A) obtained in Production Example 2 alone as a resin component to obtain a milky white aqueous dispersion. .

Comparative Example 3 The same operation as in Example 1 was carried out, except that 100 g of the chlorinated polyolefin (B) obtained in Production Example 3 was used alone as a resin component, but no aqueous dispersion was obtained.

Comparative Example 4 The same operation as in Example 1 was carried out except that 90 g of the carboxylic acid-modified chlorinated polyolefin (A) obtained in Production Example 1 and 10 g of the chlorinated polyolefin (B) obtained in Production Example 3 were used. To obtain a milky white emulsion.

Comparative Example 5 The same operation as in Example 1 was carried out except that 30 g of the carboxylic acid-modified chlorinated polyolefin (A) obtained in Production Example 1 and 70 g of the chlorinated polyolefin (B) obtained in Production Example 3 were used. To obtain a milky white emulsion.

Test Example 1 Table 1 shows the results of storage stability of each aqueous dispersion at 50 ° C. for one month. The aqueous dispersion of Comparative Example 5 was only obtained by separating two layers. Measurement method Appearance: Determined visually. (No change in appearance: ○) pH: Measured with a pH meter after immersion in a thermostat at 25 ° C for about 1 hour. Average particle size: Zeta sizer (measurement range 1 μm or less, MAR
Measured by VARON).

[0042]

[Table 1] Table 1 Storage stability results

Test Example 2 Examples 1 to 5 and Comparative Example 1
The liquid obtained by filtering the aqueous dispersions 2 and 4 was spray-coated on a polypropylene resin plate and dried at 80 ° C. for 30 minutes. Next, a two-component urethane top coat was applied, left at room temperature for 10 minutes, and dried at 80 ° C. for 30 minutes using a hot air drier. After the obtained coated plate was allowed to stand at room temperature for one day, the coating film was tested. Table 2 shows the results. The test method is as follows.・ Cut a cut on the surface of the adhesive coating film to reach the substrate with a cutter, 2mm
100 cross-cuts were made at intervals, and a cellophane adhesive tape was adhered thereon and peeled off in the 180 ° direction, and the number of remaining cross-cuts was counted. If the number of grids that did not peel was 100, it was evaluated as ○, and 99 or less was evaluated as ×. A cut reaching the substrate was made on the surface of the gasoline-resistant coating film with a cutter, and then the coating film was immersed in regular gasoline for 2 hours, and the state of the cut was visually observed. When no change was observed on the surface of the coating film, it was evaluated as ○, and when there was a change in appearance such as blistering and peeling, it was evaluated as ×.

Test Example 3 A heat creep resistance (long term heat resistance) test was performed as follows. A solution obtained by filtering the aqueous dispersions of Examples 1 to 5 and Comparative Examples 1, 2 and 4 was applied to a polypropylene resin plate after drying so as to have a film thickness of 10 μm, and then heated at 60 ° C.
For 10 minutes. After that, water-based urethane adhesive 100
Parts, curing agent (aliphatic polyisocyanate) 5
The partially mixed product was applied to a polypropylene resin plate at 100 g / m ² . On the other hand, the water-based adhesive and the curing agent are applied to the PVC leather to be adhered to 100 g /
It was coated so as to be in m ^2. Then, after drying at 60 ° C. for 10 minutes, both coated surfaces (polypropylene / vinyl chloride leather) were bonded together. After bonding, 20 ℃, 65Rh ×
Cured for 24 hours, load 200g in 80 ° C atmosphere, 90 hours after 24 hours
The angle creep was tested, and if it did not fall, it was evaluated as ○. Table 2 shows the results.

[0045]

Table 2 Results of coating film test and heat creep resistance test

As can be seen from Table 1, a stable aqueous dispersion cannot be obtained by using the chlorinated polyolefin alone (B). In addition, from Table 2, the carboxylic acid-containing chlorinated polyolefin alone (A) shows good adhesion to the polypropylene substrate, but poor heat resistance. On the other hand, it is understood that the aqueous dispersion containing the mixed resin of (A) and (B) of the present invention as a main component has good stability, adhesion, and heat resistance.

[0047]

According to the present invention, excellent adhesion and coating film appearance as a resin or primer for paints, inks or adhesives to a polyolefin resin molding or film can be obtained.
An aqueous dispersion having solvent resistance and giving a coating film having good heat resistance can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI C09J 123/08 (72) Inventor Hironori Muramoto 2-8-1 Iidacho, Iwakuni-shi, Yamaguchi Nippon Paper Industries Chemical Products Development Research (56) References JP-A-3-182534 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 23/28

Claims (5)

(57) [Claims] 1. A carboxylic acid-modified chlorinated polyolefin having a chlorine content of 15 to 35% by weight and (B) a number average molecular weight of 40,000 to 70,000 and a chlorine content of 20%.
Mixing ratio with chlorinated polyolefin of 40% by weight
(A) / (B) is a weight ratio of 80/20 to 40/60.
An aqueous dispersion comprising a mixed resin and being dispersed in water using a melting aid, a nonionic surfactant, and a basic substance. Wherein (A) an aqueous dispersion of claim 1 wherein the acid value of the carboxylic acid-modified chlorinated polyolefin is 10 to 100. Wherein (A) according to claim 1-2 any one aqueous dispersion according a number average molecular weight of the carboxylic acid-modified chlorinated polyolefin is 2,000 to 40,000. 4. A paint for a polyolefin substrate or a primer for a paint using the aqueous dispersion according to any one of claims 1 to 3 . 5. An adhesive for a polyolefin substrate, or a primer for an adhesive, using the aqueous dispersion according to any one of claims 1 to 3 .