JPH062834B2 - Surface treatment agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a surface treatment agent for a polyester resin molded product, which is used as a paintability improving primer for a polyester resin molded product.

[Conventional technology]

Polyester resin has excellent mechanical strength, weather resistance, heat resistance, and chemical resistance, and is used in various fields such as molded products, films, fibers. When polyester resin is used as molded product, polyester resin Since the adhesiveness to paint is poor as it is, it has been customary to use melamine paints and alkyd-melamine paints, etc., by using epoxy, polyester and acrylic surface treatment agents as primers. It was

However, these primers are poor in elasticity and may cause a large loss especially at impact at low temperature. Therefore, development of a paintability-improving primer excellent in low temperature impact resistance has been awaited.

[Problems to be solved by the invention]

It is an object of the present invention to provide a surface treatment agent that improves the adhesion of a polyester resin molded article to coating and has excellent impact resistance at low temperatures.

[Means for solving problems]

The present inventors have studied a maleic acid-modified ethylene-propylene copolymer rubber as a surface treatment agent for improving coatability of a polyester resin molded product, and as a result, as a result, a specific maleic acid-modified ethylene-propylene copolymer was used. Polymer rubber is used as a surface treatment agent for polyester resin molded products.
It was found to be effective for paintability and low temperature impact resistance,
The present invention has been reached.

That is, according to the present invention, the viscosity of a 5% by weight toluene solution at 20 ° C. in a Ford cup (NK-2 type) (hereinafter abbreviated as Ford cup viscosity) is 20 seconds or less, and the molecular weight is reduced by oxidative degradation. By reacting an ethylene-propylene copolymer rubber having a propylene content of 40 to 60% by weight with a maleic acid in the presence of a radical initiator in an aromatic hydrocarbon solvent at a temperature of 60 ° C. or higher. The obtained maleic acid-modified ethylene-propylene copolymer rubber having a maleic acid addition amount of 0.5 to 3% by weight is used in an amount of 1 to 10%.
The present invention relates to a surface treatment agent for a polyester-based resin molded article, which is characterized by using a solution containing it by weight.

Examples of the polyester-based resin molded product targeted by the present invention include a molded product of a polyester resin synthesized from dicarboxylic acid and glycols such as ethylene glycol and butylene glycol, and a mixture of resins containing these polyester resins as main components. Specifically, it is a molded product of polyethylene terephthalate, polybutylene terephthalate, and a polyester resin mixture containing these resins as main components.

The ethylene-propylene copolymer rubber used in the present invention has a Ford cup viscosity of 20 seconds or less and is oxidatively degraded to have a low molecular weight, and has a propylene content of 40.
~ 60% by weight. Propylene content is 40% by weight
If it is less than 60% by weight, it is difficult to obtain a primer excellent in impact resistance at low temperature, and if it exceeds 60% by weight, rubber elasticity becomes poor, which is not preferable. It is preferably 45 to 55% by weight.

In addition, lowering the molecular weight is essential in order to make a plummer with low viscosity and good coatability, and if a commercially available ethylene-propylene copolymer rubber is used as it is, it becomes a highly viscous solution and a practical primer is obtained. It is difficult to make.

As a method of lowering the molecular weight, for example, if the propylene content is
40-60% by weight of ethylene-propylene copolymer rubber,
A method of mechanically kneading and oxidatively degrading it in a generally known radical initiator and air atmosphere, or in a solvent,
Examples of the method include oxidative degradation by stirring at a temperature of 100 ° C. or higher. By these methods, an ethylene-propylene copolymer rubber having a Ford cup viscosity of 20 seconds or less used in the present invention can be obtained. You can

In addition, the modification of ethylene-propylene copolymer rubber with maleic acid is carried out by oxidatively degrading the low molecular weight ethylene-propylene copolymer rubber with a propylene content of 40 to 60% by weight to aromatic hydrocarbons. It is carried out by reacting maleic acids in a solvent at a temperature of 60 ° C. or higher in the presence of a radical initiator in the substantially absence of oxygen for a reaction time of 0.2 hours or longer. The amount of maleic acid added is 0.
It is possible to prepare a reaction solution containing 5 to 3% by weight of a maleic acid-modified ethylene-propylene copolymer rubber and effective as a surface treatment agent for a polyester resin molded product.

The aromatic hydrocarbon solvent used in the modification reaction in the present invention includes toluene, xylene, ethylbenzene, and the like, and preferred is toluene which is practically effective as a primer solvent.

Further, maleic acids used in the present invention include maleic acid, fumaric acid, maleic anhydride and the like, and maleic anhydride having particularly high reactivity is preferably used. The amount of maleic acid added is 0.5 to 3% by weight. The added amount is
If it is less than 0.5% by weight, the adhesion of the coating film is poor and it is not practical as a coating primer, and if it exceeds 3% by weight, the low temperature impact resistance is poor.

Therefore, the amount of maleic acid used should be such that the added amount of maleic acid is 0.5 to 3 wt% by the reaction, and 100 wt. It is usually in the range of 1 to 15 parts by weight with respect to parts.

As the reaction temperature, when the temperature is lower than 60 ° C, the addition amount of maleic acid is low, and it is difficult to obtain the preferred surface treatment agent of the present invention. Therefore, a temperature of 60 or higher is used. Appropriate.

The radical initiator used in the modification reaction is one that generates free radicals at the modification reaction temperature and accelerates the addition reaction of maleic acids to the ethylene-propylene copolymer rubber having a low molecular weight by oxidative degradation. Any of them can be used, but specifically, azobisisobutyronitrile, azobisvaleronitrile, benzoyl peroxide, t-butylpenoxyisobutyrate, t-butylperoxybenzoate, 1 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, dicumyl peroxide, 2,5 dimethyl 2,5 di (t
-Butylperoxy) hexane and the like are preferable, but benzoyl peroxide, 1,1-bis (t-butylperoxy) 3,3,5trimethylcyclohexane and the like are preferable, although depending on the modification reaction temperature.

Further, the amount of the radical initiator used is appropriately in the range of 10 to 50% by weight with respect to the amount of maleic acid used in the modification reaction, and it is also possible to divide and use.

The maleic acid-modified ethylene-propylene copolymer rubber concentration in the reaction solution is in the range of 1 to 10% by weight. If it is less than 1% by weight, the thickness of the coating film is thin in a single coating, and it cannot be a primer for improving coatability that is effective for impact resistance. This is because On the other hand, if it exceeds 10% by weight, the solution viscosity becomes high and it is difficult to obtain a uniform coating film. The preferred concentration is in the range of 2 to 8% by weight.

Toluene, which is usually used for paint, is added to the obtained reaction solution.
Aromatic hydrocarbon solvents such as xylene and ethylbenzene,
Hexane, heptane, octane, decane, and other aliphatic hydrocarbon solvents, chlorobenzene, dichloroethane, perchlorethylene, and other chlorinated solvents, and tetrahydrofuran, dioxane, cellosolve acetate, butyl cellosolve, ethyl acetate, butyl acetate, butyl alcohol, methyl ethyl ketone, methyl It is also possible to mix a polar solvent such as isobutyl ketone according to the purpose and use it as a surface treatment agent.

It is also possible to use the surface treatment agent of the present invention by mixing with stabilizers, colorants, organic and inorganic compounding agents and the like which are generally known in the field of coating materials.

The surface treatment agent according to the present invention can be applied to a polyester resin molded article by a commonly known method such as brush coating, spray coating, electrostatic coating, or the like, and the surface treatment is performed by air drying or baking. A coating of agent can be made.

The polyester-based resin molded article which has been surface-treated with the surface-treating agent according to the present invention can be coated by a conventionally known coating method according to a known coating method,
In particular, it is possible to obtain a polyester resin molded product having excellent impact resistance even when applied to a melamine resin coating or a melamine-alkyd resin coating having a high surface hardness.

Further, the surface treatment agent of the present invention was developed for a polyester resin molded product having poor adhesiveness to a paint, but polyethylene, polypropylene, polyvinyl chloride, unsaturated polyester resin, nylon, polyurethane, etc. It can also be used for molded products.

〔Example〕

Next, the present invention will be described in more detail with reference to Examples. The amount of maleic acid added to the modified ethylene-propylene copolymer rubber was determined by heating a solution of the modified rubber in toluene and phenolphthalein as an indicator under heating. It was determined by titration with a KOH ethanol solution. Also, the intrinsic viscosity was obtained from a xylene solution at 70 ° C.

Example 12 stainless steel autoclave ethylene-propylene copolymer rubber (propylene content 53% by weight, intrinsic viscosity
1.9) 50 g, 1,1-bis (t-butylperoxy) 3,3,5
0.5 g of trimethylcyclohexane (hereinafter abbreviated as “Perhexa 3M”) and 800 g of toluene were taken, and oxidative degradation was carried out at 150 ° C. for 4 hours while stirring in an air atmosphere. After cooling, the polymer was precipitated with acetone and recovered to obtain an ethylene-propylene copolymer rubber having an intrinsic viscosity of 1,1. In addition, this low molecular weight ethylene-
The Ford cup viscosity of the propylene copolymer rubber was 11 seconds.

Next, 50 g of the obtained low molecular weight ethylene propylene copolymer rubber, 3.0 g of maleic anhydride, and Perhexa 3M0.6
g and 800 g of toluene in a 2 stainless steel autoclave at 125 ° C with stirring under a nitrogen atmosphere.
The denaturation reaction was performed for 1.5 hours. After cooling, a part of the reaction solution was analyzed, and it was found that the reaction solution contained an ethylene-propylene copolymer rubber having a maleic anhydride addition amount of 1,5% by weight.
It contained 6.0% by weight.

The obtained reaction solution was diluted with tolue so that the concentration of the maleic anhydride-modified ethylene-propylene copolymer rubber was 5.0% by weight and prepared as a surface treatment agent.

Next, polypropylene terephthalate resin (Toray Industries, Inc.)
After degreasing an injection-molded plate (50 mm × 50 mm × 3 mm) manufactured by Mfg. Co., Ltd.) with isopropanol, the prepared surface treatment agent was applied and baked at 120 ° C. for 30 minutes.

Next, an alkyd-melamine-based paint (manufactured by Kansai Paint Co., Ltd.) was applied and baked at 140 ° C for 30 minutes to prepare an alkyd-melamine-coated polybutylene terephthalate plate. Water-based and impact-resistant coating film tests were conducted, and the results were all good. The results are shown in Table 1.

<Adhesiveness> 100 pieces of crevices were made on the coated surface with a knife at 1mm intervals, and adhesive tape (18mm UNICELOHAN tape manufactured by Mitsubishi Pencil Co., Ltd.) was applied on top of this, and the adhesive tape was peeled 90 °. It is represented by the number of goggles left (hereinafter referred to as a goggles test).

<Warm water resistance> A goose eye test after immersion in hot water at 50 ° C for 240 hours.

<Low temperature impact resistance> Impact resistance at −30 ° C. was tested using a DuPont impact tester.

○ Good (ductile fracture) △ Inferior (ductile part is also seen but brittle fracture) × Bad (brittle fracture) Example 2 In Example 1, the addition amount of maleic anhydride and the addition amount of Perhexa 3M were 2.5, respectively. g and 0.5 g, except that the reaction was carried out in the same manner as in Example 1 to obtain a surface treating agent containing a maleic anhydride-modified ethylene-propylene copolymer rubber having an addition amount of maleic anhydride of 1.0% by weight. .

Next, when the coating film performance was evaluated in the same manner as in Example 1, good results were obtained as shown in Table 1.

Example 3 The internal volume heated by circulation of a heat medium (180 ° C) was 80 ml.
Brabender plast mill of No. 1 was mixed with 0.7 PHR of Perhexa 3M in advance by a mixing roll, and ethylene-propylene copolymer rubber (propylene content 47
Charge 50% by weight, intrinsic viscosity 2.2). Then add 10
/ Min, and kneaded at 100 rpm for 5 minutes for oxidative degradation to obtain a low molecular weight ethylene-propylene copolymer rubber having an intrinsic viscosity of 1.2 and a Forcup viscosity of 12 seconds.

The modification with maleic anhydride was performed in the same manner as in Example 2 to obtain a solution containing 6.1% by weight of the modified ethylene-propylene copolymer rubber having a maleic anhydride addition amount of 1.1% by weight.

Next, using toluene, maleic anhydride modified ethylene-
When the surface treatment agent was prepared by diluting the propylene copolymer rubber concentration to 4.0% by weight and evaluated in the same manner as in Example 1, the coating film had good physical properties (No. 1).
table).

Comparative Example 1 In Example 1, the propylene content was 22% by weight and the intrinsic viscosity was 1.
A surface treating agent was prepared by lowering the molecular weight and modifying with maleic anhydride in the same manner as in Example 1 except that the ethylene-propylene copolymer rubber of 5 was used.

The coating film performance was evaluated in the same manner as in Example 1, but the low temperature impact resistance was particularly poor.

Example 2 The ethylene-propylene copolymer rubber obtained in Example 1 was subjected to a modification reaction using 0.7 g of maleic anhydride and 0.14 g of Perhexa 3M without lowering the molecular weight (Ford cup viscosity of 40 seconds). Others were the same as in Example 1 to obtain a solution containing 6.0% by weight of a modified ethylene-propylene copolymer rubber having a maleic anhydride addition amount of 0.4% by weight.

The following operations were performed in the same manner as in Example 1 to evaluate the physical properties of the coating film, but the adhesion and hot water resistance were particularly poor (first
table).

Comparative Example 3 Example 1 was repeated except that the amounts of maleic anhydride and perhexa 3M added were 7.2 g and 1.5 g, respectively.
In the same manner, a maleic anhydride-modified ethylene-propylene copolymer rubber solution having a maleic anhydride addition amount of 3.8% by weight was obtained.

The following operations were performed in the same manner as in Example 1 to evaluate the coating film performance, but the low temperature impact resistance was particularly poor (Table 1).

〔The invention's effect〕

As described above, according to the present invention, a surface treatment agent having excellent adhesion to coating of a polyester resin molded product and excellent impact resistance at low temperature can be obtained by oxidizing a surface treatment agent having a Ford cup viscosity of 20 seconds or less. For ethylene-propylene copolymer rubbers with propylene content of 40-60% by weight, which have been degraded and reduced in molecular weight, maleic acid was prepared in the presence of a radical initiator in an aromatized hydrocarbon solvent at a temperature of 60 ℃ or higher. The amount of added maleic acid obtained by reacting acids is
It can be provided as a solution containing 0.5 to 3% by weight of a maleic acid-modified ethylene-propylene copolymer rubber in an amount of 1 to 10% by weight.

Claims (2)

[Claims] 1. The viscosity of a 5% by weight toluene solution at 20 ° C. measured by a Ford cup (NK-2 type) is 20 seconds or less,
Oxidative degradation and low molecular weight, propylene content 40 ~
With respect to 60% by weight of ethylene-propylene copolymer rubber,
Maleic acid-modified ethylene-propylene copolymer having a maleic acid addition amount of 0.5 to 3% by weight obtained by reacting maleic acids in the presence of a radical initiator in an aromatic hydrocarbon solvent at a temperature of 60 ° C. or higher. A surface treatment agent for a polyester resin molded product, which comprises using a solution containing 1 to 10% by weight of a united rubber. 2. The surface treating agent according to claim 1, wherein the aromatic hydrocarbon solvent is toluene.