MXPA00007712A - Water base adhesion promotor for polypropylene and method for coating to polypropylene materials using the promotor - Google Patents

Abstract

The water base adhesion promotor for polypropylene comprises:a grafted polypropylene chloride, which includes a polypropylene chloride moiety and a maleic anhydride moiety as bonded thereto, and which has a chlorine content of 15-25 weight%and a maleic anhydride moiety content of 1-5 weight%;an amine-neutralized water-soluble resin;a wettability-improving agent;and water;and is characterized by having:a combination ratio of 25-90 weight%as of the grafted polypropylene chloride to the total of the grafted polypropylene chloride and the amine-neutralized water-soluble resin;a combination ratio of 2.5-6.0 weight%as of the wettability-improving agent to the entirety of the promotor;and a solid content of 2-10 weight%of the entirety of the promotor. The method for coating to polypropylene materials comprises:a pretreatment step in which the polypropylene material is beforehand cleaned and then the above water base adhesion promotor is applied, and then dried;and a coating step in which a paint is coated to the material after the pretreatment step.

Description

PROMOTER OF ADHESION IN AQUEOUS BASE FOR POLYPROPYLENE AND METHOD TO COVER POLYPROPYLENE MATERIALS USING THE PROMOTER TECHNICAL FIELD The present invention relates to: an adhesion promoter in aqueous base to improve the adhesion of paint to polypropylene materials; and a method for coating polypropylene materials using the promoter.

ANTECEDENTS OF THE TECHNIQUE Polyolefins such as polypropylene are comparatively inexpensive and have excellent properties, such as formability and chemical resistance, therefore they are widely used in industrial fields, including the automotive industry. The amount of them as used tends to increase, because their recycling is possible and because their prices are low. Polypropylene materials are, for example, used for automotive exterior decoration parts, such as fenders and molds, and their surfaces are usually coated both to improve their weather resistance and to give the design property thereto.

REF .: 121559 The polypropylene material is lower in wettability. Therefore, when coated with a paint, the polypropylene material is subjected to the following treatments: first, a degreasing treatment with an aqueous based cleaning agent and a pretreatment to increase the wettability using a surfactant, and then treatments of coating and firing a primer, and then a coating treatment of a paint. Incidentally, the coating treatment of the primer is carried out to increase the adhesion of paints, but, in reality, up to about 70% of the amount of the primer as used is loss during the application and therefore not used effectively, so it results in a high coating cost. In addition, there are problems in that: the primer needs to be baked after being coated, so a large baking oven is needed and therefore the cost of the equipment is high.

From the above circumstances, it is desired to develop a method for coating polypropylene materials without a primer coating.

DESCRIPTION OF THE INVENTION OBJECTIVE OF THE INVENTION An object of the present invention is to provide: an aqueous-based adhesion promoter to increase the adhesion of paint to polypropylene materials in place of the primer coating; and a method of coating polypropylene materials using the promoter.

BRIEF DESCRIPTION OF THE INVENTION The present inventors do various examinations and experiments to solve the above problems. As a result, they achieved the present invention by finding that: a composition, comprising a polypropylene chloride grafted with high adhesion to polypropylene materials, a water-soluble resin neutralized with high water-resistance amine, and an agent that improves wettability, it could increase the adhesion of paint to polypropylene materials, so that the primer coating could be omitted.

That is, an aqueous-based adhesion promoter for polypropylene, according to the present invention, comprises: a grafted polypropylene chloride, which includes a part of polypropylene chloride and a part of maleic anhydride as attached thereto, and which has a chlorine content of 15-25% by weight and a content of maleic anhydride of 1-5% by weight; a water-soluble resin neutralized with amine; an agent that improves wettability; Y water, - and is characterized by having: a mixing ratio of 25-90% by weight relative to the grafted polypropylene chloride for the total of the grafted polypropylene chloride and the water-soluble resin neutralized with amine; a combination ratio of 2.5-6.0% by weight relative to the agent that improves wettability for the entire promoter; Y a solids content of 2-10% by weight of the entire promoter.

A method for coating polypropylene materials, according to the present invention, comprises: a pretreatment step in which a polypropylene material is previously cleaned, and then the adhesion promoter in aqueous base is applied, then dried; Y a coating step in which a paint is coated to the material after the pre-treatment step.

DETAILED DESCRIPTION OF THE INVENTION Next, each component, which constitutes the water-based adhesion promoter of the present invention for polypropylene, is explained in detail, and then the aqueous-based adhesion promoter for polypropylene and the method for coating polypropylene materials are explained.

(Grafted polypropylene chloride): The grafted polypropylene chloride, as used in the present invention, is a component that increases adhesion to polypropylene materials. The grafted polypropylene chloride is a polypropylene derivative, which includes a part of polypropylene chloride and a portion of maleic anhydride as attached thereto, and is usually used in the form of an emulsion having the high handling property.

The polypropylene chloride portion is a part comprising a polypropylene having at least one chlorine atom as a substituent. In addition, the maleic anhydride portion is a part as obtained by grafting maleic anhydride, and has a cyclic acid anhydride group (derived from maleic anhydride) and / or two free carboxyl groups.

The grafted polypropylene chloride is a product by reacting a polypropylene with maleic anhydride and chlorine to internally graft the polypropylene, and is, for example, produced by reacting chlorine and maleic anhydride with a polypropylene. Incidentally, any of chlorine and maleic anhydride can be reacted before the other. The reaction with chlorine is, for example, carried out by introducing a chlorine gas into a solution including a polypropylene. In addition, the reaction with maleic anhydride is, for example, carried out by reacting maleic anhydride with a polypropylene (or its chloride) in the presence of a peroxide.

The chlorine content in the grafted polypropylene chloride is in the range of 15-25% by weight, preferably 18-22% by weight. In the case where the chlorine content is less than 15% by weight, the melting temperature of the grafted polypropylene chloride is high, so that crystallization easily occurs and emulsification is difficult, so it results in a decrease in the storage stability of the resulting aqueous base adhesion promoter. On the other hand, in the case where the chlorine content exceeds 25% by weight, the grafted polypropylene chloride is not crystalline, so it results in a decrease in adhesion and water resistance.

The content of part of maleic anhydride in the grafted polypropylene chloride is in the range of 1-5% by weight, preferably 3-4.5% by weight. In the case where the content of part of maleic anhydride is less than 1%, therefore, the emulsification is difficult, so that results in a decrease in the storage stability of the adhesion promoter in aqueous base. On the other hand, in the case where the content of part of maleic anhydride exceeds 5% by weight, the group content of acid anhydride is too much, so it results in a decrease in adhesion and water resistance.

The weight average molecular weight of the grafted polypropylene chloride is not particularly limited, but is preferably in the range of 20,000-100,000, preferably 30,000-80,000. In the case where the average molecular weight per weight is less than 20,000, the promoter could swell with a solvent for a higher paint, so that the adhesion could deteriorate. On the other hand, when the average molecular weight per weight exceeds 100,000, the viscosity of the resulting aqueous based adhesion promoter could be high, so that the emulsification could be difficult and the storage stability could be low.(Resin soluble in water neutralized with amine): The water-soluble resin neutralized with amine, as used in the present invention, is a resin as it is solubilized in water by neutralization with an amine, and is a film conformable component having high water resistance. Incidentally, for example, water-soluble resins, which are not obtained by neutralization with amine, such as polyethylene glycol and polyvinylpyrrolidone, merely have low water resistance, because, even after film formation by drying , such water-soluble resins maintain and retain their solubility in water. In comparison, the water-soluble resin neutralized with amine, as used in the present invention, shows high water resistance, because it volatilizes the amine in the drying step, and thus loses the solubility in water.

The water-soluble resin neutralized with amine, as used in the present invention, is not particularly limited if it is a resin as neutralized with an amine, and examples thereof include products by neutralization of resins, such as resins of urethane, alkyd resins, and acrylic resins. These can be used either alone or in combinations with each other.

Examples of the amine, as used for the above neutralization, include ammonia, triethylamine, and monoethanolamine. These can be used either alone or in combinations with each other.

(Agent that improves wettability): The agent that improves wettability, as used in the present invention, is a component that increases the wettability of the water-based adhesion promoter in polypropylene materials (which have a high water-repelling strength). The use of this agent that improves wettability allows a coating film, resulting from the grafted polypropylene chloride and the water-soluble resin neutralized with amine as mentioned above, to adhere well to polypropylene materials.

The agent that improves wettability is not particularly limited, but examples thereof include ethylene glycol hexyl ether, dimethylpolysiloxane-polyethylene glycol block polymer (Polyflow KL-245). These can be used either alone or in combinations with each other. Particularly, ethylene glycol hexyl ether improves wettability, and in addition water resistance does not decrease because it volatilizes in the drying step and therefore does not stay in the resulting coating film. In comparison, materials as conventionally used to increase wettability, such as alkylphenyl polyethylene glycol, are not volatilized in the drying step, but remain in the coating film, so water resistance decreases.

(Other components) : The water-based adhesion promoter of the present invention may further comprise the following different components: resin emulsions, such as acrylic emulsions, urethane emulsions, and polyvinyl chloride emulsions; inorganic pigments, such as titanium white and carbon black, extenders, such as talc and precipitated barium; and several organic color pigments.

(Adhesion promoter in aqueous base for polypropylene and method for coating): The water-based adhesion promoter for polypropylene, according to the present invention, needs to comprise the grafted polypropylene chloride, the water-soluble resin neutralized with amine, the agent that improves wettability, and water (these components are explained in detail above), and may also comprise the other components above if necessary. The conditions, such as order, for mixing these components are not especially limited.

The proportion of the combination of the grafted polypropylene chloride, as it is contained in the adhesion promoter of the present invention for polypropylene, is in the range of 25-90% by weight, preferably 30-50% by weight, of the total (the total solids content) of the grafted polypropylene chloride and the water-soluble resin neutralized with amine.

In the case where the proportion of the combination of the grafted polypropylene chloride is less than 25% by weight, the adhesion and the water resistance are both low. On the other hand, in the case where the proportion of the combination of the grafted polypropylene chloride exceeds 90% by weight, the adhesion and the water resistance, as well as the formability of the film are low.

The mixing ratio of the agent that improves wettability is in the range of 2.5-6.0% by weight, preferably 3.0-4.0% by weight, of the entire water-based adhesion promoter. In the case where the mixing ratio of the wetting enhancing agent is less than 2.5% by weight, the polypropylene material is entrained with the water-based adhesion promoter, so uniform coating is impossible. On the other hand, in the case where the proportion of the combination of the agent improving the wettability exceeds 6.0% by weight, the storage stability of the adhesion promoter in aqueous base is low, and the aggregates of grafted polypropylene chloride precipitate.

The solids content of the water-based adhesion promoter of the present invention for polypropylene is the non-volatile material and is in the range of 2-10% by weight, preferably 4-6% by weight, of the entire promoter of adhesion in aqueous base. In the case where the solids content is less than 2% by weight, the film thickness of the coating film resulting from the water-based adhesion promoter is too thin, so the adhesion and the water resistance are both low . On the other hand, in the case where the solids content exceeds 10% by weight, slip marks are left after coating the water-based adhesion promoter, so the resulting coating film has no uniformity, and the appearance is therefore unfavorable.

The method of coating polypropylene materials, according to the present invention, comprises the pretreatment step and the top coating step.

The pretreatment step includes the steps of cleaning the polypropylene material and applying the adhesion promoter in aqueous base and then drying the material.

The cleaned polypropylene material is, for example, prepared by the following steps 1-3 in the pretreatment step. (1) One step of spraying a polypropylene material with hot water of 60-80 ° C. (2) A step of degreasing the polypropylene material with an alkaline cleaning agent after step (1) above. (3) A step of removing the alkaline cleaning agent from the polypropylene material by spraying the polypropylene material with deionized water after step (2) above.

The coating film of the water-based adhesion promoter is formed on the surface of the polypropylene material by applying the water-based adhesion promoter on the cleaned polypropylene material and then drying the material. This application step can be carried out by, for example, decanting, atomizing spray, immersion and / or showering. The choice of a given application step for any specific part can be based on economic, process, and quality considerations. For certain parts it is preferable to keep the polypropylene material vertically after the application step and then dry the material. For other parts, notably those in which the coating material can be attached and / or deviate from the vertical after application, it is preferable to keep the polypropylene material at a small angle, preferably about 10-20 ° and so more preferable about 15 ° from the vertical during drying.

During the retention step, it is preferred to maintain an atmosphere within the medium to promote even a coating after drying, for example, the retention medium can preferably be maintained at a temperature between about 15-30 ° C and about 40-70. % relative humidity and preferably between 20-25 ° C and approximately 40-70% relative humidity. This retention step is commonly referred to as a quick condition.

The method for drying after the fast condition is not particularly limited, and drying is usually carried out with ovens, such as hot air drying ovens, long wave infrared ovens, and short wave infrared ovens at about 60-120 ° C for approximately 5-15 minutes. The thickness of the dried film, as obtained from the aqueous base adhesion promoter in the above manner, is preferably in the range of 0.1-1 μm.

The coating step includes the step of coating a top paint to the previous material after the pretreatment step and is carried out by coating the top paint and then drying it.

The type of the top paint is not particularly limited, but examples thereof include one-component melamine baking paints, two-component urethane paints, and one-component lacquer paints.

The method of coating the upper paint is not particularly limited, but spray coating is preferable. The method of drying the coated upper paint is not particularly limited, and drying is usually carried out with ovens, such as hot air drying ovens, long wave infrared ovens, and short wave I infrared ovens. at 70-120 ° C for 20-60 minutes. The thickness of the dried film i, as obtained from the upper paint i in the above manner, is not particularly limited, but is preferably in the range of 15-60 μm. i i! In the method of coating polypropylene materials, the use of the above aqueous base adhesion promoter in the pretreatment step I allows for the omission of the primer coating. Therefore, productivity in the coating step is greatly improved.

BEST MODE FOR CARRYING OUT THE INVENTION I I I Next, the present invention is illustrated further! I specifically by the following examples of certain preferred embodiments compared to the comparative examples not according to the invention. However, the invention is not limited to the examples mentioned above. Next, the unit "part (s)" is "part (s) by weight".

(EXAMPLE 1) First, 6 parts (non-volatile material: 1.8 parts) of a grafted polypropylene chloride emulsion (chlorine content = 16% by weight, content of part of maleic anhydride = 1.5% by weight, non-volatile material = 30% by weight ), 12 parts (non-volatile matter: 4.2 parts) of a water-soluble urethane (made by Sanyo Kasei Co., Ltd., U-Coat U S-145, non-volatile matter = 35% by weight) (as the water-soluble resin neutralized in amine), 3 parts of ethylene glycol hexyl ether (as the agent that improves wettability), and 79 parts of water were mixed in this order under agitation, thus the adhesion promoter in aqueous base (1) of 100 parts in total is prepared. Incidentally, the proportion of (grafted polypropylene chloride) / (water-soluble resin neutralized with amine) (ratio in terms of solids content) was 30/70, and the proportion of ethylene glycol hexyl ether combination was 3% by weight of the totality of water-based adhesion promoter (1), and the content of adhesion promoter solids in aqueous base (1) was 6% by weight as determined from its non-volatile material.

A polypropylene material was spray-washed with hot water of 60-80 ° C, and then degreased by washing by spraying with an alkaline cleaning agent (Surf Cleaner PL-1000, made by Nippon Paint Co., Ltd.), and then it was washed by spraying with room temperature deionized water to remove the alkaline cleaning agent in the wash, thereby preparing a washed polypropylene material. This polypropylene material was immersed in adhesion promoter in aqueous base (1), and then left to stand vertically at room temperature for 1 minute, and then dried at 80 ° C for 10 minutes. Then, a polyester resin paint of the isocyanate-curing type (R-763, made by Morton Nippon Coatings Co., Ltd.) (as the top paint) was spray coated onto the above polypropylene material, and then the paint The coating was dried at 80 ° C for 40 minutes, thereby obtaining coated product (1). Incidentally, the dry film thickness was in the range of 15-25 μm.

The properties of the adhesion promoter in aqueous base (1) were evaluated by the following methods. The results thereof are shown in Table 1.

(Evaluation method): 1. Adhesion: A cross-sectional test was carried out for the coated product in accordance with JIS K5400. First, 100 cross sections of 2 mm x 2 mm were prepared to carry out the peel test of the cellophane tape, and the evaluation was done in the following evaluation standard: O: no peeling was observed; x: one or more cross sections completely peeled. 2. Waterproof: The coated product was immersed in hot water of 80 ° C for 3 hours, and then the water was removed on the surface. Then, the coated product was left for 1 hour, and then the evaluation of the previous adhesion was carried out. The evaluation standard was the same as that for membership. 3. Appearance: A polypropylene material of 7.5 cm x 10 cm was prepared, and then treated with the adhesion promoter in aqueous base, and then placed vertically, and then dried at 80 ° C for 30 minutes, thereby evaluating itself a shift mark was observed or not with the eye in the following evaluation standard: O: no bleed mark, - x: one bleed mark was observed. 4. Storage stability: A polypropylene material was immersed in the adhesion promoter in aqueous base as it was stored at room temperature for 1 month, in this way it is evaluated whether an aggregate was observed or not with the eye in the following evaluation standard: O: no aggregate, - x: an aggregate was observed.

(EXAMPLES 2-4 AND COMPARATIVE EXAMPLES 1-7! The water-based adhesion promoters (2) ~ (4) and comparative aqueous base adhesion promoters (1) ~ (7) were prepared to evaluate their properties in the same manner as in Example 1, except that the type and the The amount of combination of the grafted polypropylene chloride emulsion and the combination amounts of the water-soluble urethane and the ethylene glycol hexyl ether were charged to those as shown in Tables 1 and 2. Tables 1 and 2 further show the proportion of (grafted polypropylene chloride) / (water soluble resin neutralized with amine) (ratio in terms of solids content) and the proportion of combination and the solids content of ethylene glycol hexyl ether.

Table 1 r-o ro * 1 amount of each component in 100 parts by weight of adhesion promoter in aqueous base; the balance is water.

Table 2 * 1 amount of each component in 100 parts by weight of adhesion promoter in aqueous base; the balence is water < Evaluation results > : Examples 1-4 all provide excellent results with respect to adhesion, water resistance, appearance, and storage stability, and allow the omission of the conventional primer coating step. Comparative Examples 1 and 2 provide inferior results with respect to adhesion and water resistance, because the blending ratio of the grafted polypropylene chloride is outside the claimed range. Comparative Example 3 provides inferior results with respect to adhesion and water resistance, because the chlorine content of the grafted polypropylene chloride is too great. Comparative Example 4 provides inferior results with respect to adhesion and water resistance, because the content of part of maleic acid is too large. Comparative Example 5 provides inferior results with respect to storage stability, because the combination ratio of the ethylene glycol hexyl ether is too large. Comparative Example 6 provides inferior results with respect to adhesion and water resistance, because the coating film resulting from the water-based adhesion promoter is thin due to the too small solids content. Comparative Example 7 provides inferior results with respect to appearance, because the coating film resulting from the water-based adhesion promoter is coarse due to the too large solids content.

INDUSTRIAL APPLICATION The use of the water-based adhesion promoter of the present invention for polypropylene in the pretreatment step prior to the coating of polypropylene materials allows for the omission of the primer coating, and in addition, provides excellent results with respect to the adhesion of the paint and the water resistance and appearance of the coating film.

The method of the present invention for coating polypropylene materials comprises the use of the water-based adhesion promoter in the pretreatment step and therefore allows the omission of the primer coating and the large improvement of coating step productivity. In addition, in this method, the water-based adhesion promoter that does not remain in the polypropylene material can be recovered and recycled through the process, providing economic benefits to the process.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, the content of the following is claimed as property.

Claims (13)

1. A water-based adhesion promoter for polypropylene, characterized in that it comprises: a grafted polypropylene chloride, which includes a part of polypropylene chloride and a part of maleic anhydride as attached thereto, and which has a chlorine content of 15-25% by weight and a content of part of maleic anhydride 1-5% by weight; a water-soluble resin neutralized with amine; an agent that improves wettability; Y Water; where you have: a mixing ratio of 25-90% by weight relative to the grafted polypropylene chloride for the total of the grafted polypropylene chloride and the water-soluble resin neutralized with amine; a combination ratio of 2.5-6.0% by weight referring to the agent that improves wettability for the entire promoter; Y a solids content of 2-10% by weight of the entire promoter.

2. An aqueous-based adhesion promoter for polypropylene according to claim 1, characterized in that the agent that improves wettability is ethylene glycol hexyl ether.

3. A method for coating polypropylene materials, characterized in that it comprises: pretreat, in which a polypropylene material is previously cleaned, and then applying thereto an aqueous base adhesion promoter comprising: a grafted polypropylene chloride, which includes a part of polypropylene chloride and a part of maleic anhydride as attached thereto, and which has a chlorine content of 15-25% by weight and a content of part of maleic anhydride 1-5% by weight; a water-soluble resin neutralized with amine; an agent that improves wettability; Y Water; where you have: a mixing ratio of 25-90% by weight relative to the grafted polypropylene chloride for the total of the grafted polypropylene chloride and the water-soluble resin neutralized with amine; a combination ratio of 2.5-6.0% by weight relative to the agent that improves wettability for the entire promoter; Y a solids content of 2-10% by weight of the entire promoter; dry the pretreated material; and coating, in which a paint is coated to the pretreated material after pretreatment.

4. The method according to claim 3, characterized in that the agent that improves wettability is ethylene glycol hexyl ether.

5. The method according to claim 3, characterized in that the application comprises decanting, spray atomization, immersion and / or showering.

6. The method according to claim 3, characterized in that it also comprises retaining the pretreated material before drying.

7. The method according to claim 6, characterized in that the retention is carried out in a medium having a temperature of between about 15-30 ° C and a relative humidity of between about 40-70%.

8. The method according to claim 6, characterized in that the retention is carried out in a medium having a temperature of between about 20-25 ° C and a relative humidity of between about 40-70%.

9. The method according to claim 6, characterized in that the pretreated material is maintained in vertical position.

10. The method according to claim 6, characterized in that the pretreated material is maintained at an angle of between approximately 10-20 ° from the vertical.

11. The method according to claim 3, characterized in that the adhesion promoter that does not remain in the polypropylene material after the application is recovered and recycled.

12. The method according to claim 3, characterized in that the drying is carried out at a temperature between about 60 ~ 120 ° C.

13. The method according to claim 12, characterized in that the drying is carried out in approximately 5-15 minutes. SUMMARY OF THE INVENTION The present invention relates to an adhesion promoter in aqueous base, which comprises: a grafted polypropylene chloride, which includes a part of polypropylene chloride and a part of maleic anhydride as attached thereto, and which has a chlorine content of 15-25% by weight and a content of part of maleic anhydride 1-5% by weight; a water-soluble resin neutralized with amine; an agent that improves wettability; Y Water; and is characterized by having: a mixing ratio of 25-90% by weight relative to the grafted polypropylene chloride for the total of the grafted polypropylene chloride and the water-soluble resin neutralized with amine; a combination ratio of 2.5-6.0% by weight referring to the agent that improves wettability for the entire promoter; Y a solids content of 2-10% by weight of the entire promoter. The method for coating polypropylene materials comprises: a pretreatment step in which the polypropylene material is pre-cleaned and then the water-based adhesion promoter is applied, and then dried; Y a coating step in which a paint is coated to the material after the pre-treatment step.