JP6153435B2 - Aqueous primer composition for paint stripping and paint stripping method - Google Patents

Description

  The present invention is a paint that enables efficient removal of a hardened or uncured paint or paint film that adheres to and accumulates on coating equipment used in the painting process of various objects including the painting process of automobiles. The present invention relates to a stripping aqueous primer composition and a coating stripping method.

  Painting equipment is used in various painting processes, including the painting process of automobiles. If paint adheres to and accumulates on these painting equipment, workability and function deteriorate, so painting is performed at regular intervals. It is necessary to remove the cured or uncured paint from the instruments.

Examples of the painting tools used in the painting process of painting an object to be painted such as an automobile include a masking jig, a snowboard, a painting booth, and the like. Conventionally, various methods have been proposed as a method for removing the coating film adhering to the coating instruments.
(i) A method using a paint remover mainly composed of an organic solvent such as dichloromethane or thinner
(ii) A method of heating and using an aqueous detergent mainly composed of caustic, (iii) A method of incineration, and (iv) A method of applying physical vibration or impact using a hammer or a scraper. (V) A method of coating a silicone resin or a fluororesin that prevents adhesion of paint is known.

  However, in the case of method (i), those that are peeled off with a solvent use a flammable solvent such as xylene or ketone, or a chlorine-based solvent such as dichloromethane as the paint remover, so that the work environment is protected. Inflammation prevention measures are required. This method has many problems in terms of work hygiene such as toxicity, odor, flammability and waste liquid treatment, and environmental pollution. In particular, the use of a paint stripper mainly composed of dichloromethane is widely known and used as a prior art, but it has become difficult to use at present when there are concerns about the effects on the human body such as the development of bile duct cancer. . In the case of the method (ii), there is a problem in safety because the concentration of the alkali component is high. In addition, when the concentration of caustic alkali that is often used is 5% or more, handling is complicated because it is designated as a deleterious substance in the Poisonous and Deleterious Poison Control Law. In addition, method (iii) has a problem in terms of air pollution because it involves generation of toxic exhaust gas. Furthermore, in the case of the method (iv), not only is it difficult to completely peel off the details, but there is a high risk of deforming and damaging the coating instruments, and there is a problem that the working efficiency is extremely low. In the case of (v), the adhesion of the paint cannot be completely prevented, and it is not popular because of high costs and concerns about paint repelling. Through the method (i) to the method (v), there is a drawback that it is difficult to remove the adhered paint as a whole.

  As another method, a primer is coated in advance on the part of the paint apparatus where the paint adheres, and after the paint has adhered and deposited to some extent in the painting process, it is peeled off with a water-soluble paint remover (Patent Document 1) or a solvent. There is something to do. When peeling with a water-soluble paint remover, polyvinyl alcohol, polyvinyl pyrrolidone, water-soluble acrylic resin, etherified cellulose, etc. (Patent Documents 2, 3, 4, 5, 6) do not have sufficient peeling performance.

  High viscosity grease is widely used as an oil-type paint peeling primer because it is inexpensive and effective, but it is easily dissolved in solvent-based paints, and water-based paints have repellency and do not adhere. Contamination of the surrounding environment also becomes a problem because it causes a decrease in productivity, such as leading to defective paint products due to dropped paint, and the grease itself is highly contaminated.

JP2002-275394 JP2000-191961 JP-A-8-134386 JP 4-149284 A JP 63-209771 JP 62-246973

  In view of the situation in the field as described above, the present invention provides a cured or uncured paint or coating film that adheres to and accumulates on coating equipment used in various painting processes including automobile painting processes. An object of the present invention is to provide an aqueous primer composition for paint stripping and a paint stripping method that enable efficient removal when stripping using a water-soluble paint stripper.

In order to solve the above-mentioned problems, the present inventor has intensively studied and, as a result, has reached the present invention. That is, this invention relates to the water-based primer composition for paint peeling containing the following component, and the paint peeling method.
Item 1. An aqueous primer composition for paint stripping, comprising a polymer having a repeating structural unit represented by the following formula (1), a salt thereof, and water.

[Wherein, M represents any of hydrogen, alkali metal, ammonium ion, and alkanolamine. ]
Item 2. Item 2. The paint-peeling aqueous primer composition according to Item 1, wherein the polymer further has a repeating structural unit represented by the following formula (2).

[Wherein, M represents any of hydrogen, alkali metal, ammonium ion, and alkanolamine. ]
Item 3. Item 3. The aqueous primer composition for peeling paint according to Item 1 or 2, wherein the concentration of the polymer and the salt thereof is 1 to 50% by mass.
Item 4. Item 4. The aqueous primer composition for peeling paint according to any one of Items 1 to 3, wherein the polymer is polystyrene sulfonic acid or a salt thereof, or maleic acid polystyrene sulfonate or a salt thereof. Item 5. A paint that removes a cured or uncured paint from a coating instrument by applying the aqueous primer composition for removing the paint according to any one of items 1 to 4 to a paint instrument before painting, and using a paint remover after painting Peeling method.

  Coating equipment that has a coating of water-based primer for removing paint (preferably polystyrene sulfonic acid and its salt or polystyrene sulfonic acid maleic acid and its salt) on its surface is water-soluble even if unnecessary paint is deposited or deposited. When treated with a paint remover, cracks occur in the adhered paint, and the water-soluble paint remover penetrates into the cracks and dissolves and swells the film. Peel off. Therefore, according to the paint-peeling water-based primer of the present invention, it is possible to easily peel off the adhered and accumulated paint in a short period of time, such as a corner or a bent part of a coating instrument, even at a site where paint removal is relatively difficult. be able to.

  Further, after the paint peeling treatment, a water washing treatment is generally performed. However, since the film formed from the primer according to the present invention is dissolved and removed with water, no poor adhesion of the paint occurs when a new film is formed.

  Hereinafter, the aqueous primer composition for peeling paint according to the present invention will be described in detail. The aqueous primer composition for peeling paint according to the present invention is characterized by containing a polymer having a repeating structural unit represented by the following formula (1), a salt thereof and water.

  In the formula, M is an alkali metal such as hydrogen, Li, Na, K, or Cs or an ammonium ion, an alkanolamine such as monoethanolalkanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, or triisopropanolamine. 1 or more types selected from In the repeating structural unit represented by the plurality of formulas (1) in the polymer, a plurality of M may be the same or different.

  In the formula (1), the position of the sulfonic acid group is not specified and may be in the para position or the meta position.

  Polystyrene sulfonic acid can be mentioned as a polymer which has a repeating structural unit represented by Formula (1).

  In the polymer, the repeating structural unit represented by the formula (1) is contained in an amount of 25% by mass to 100% by mass based on the monomer.

  The molecular weight (weight average molecular weight) of polystyrene sulfonic acid and its salt is 10,000 to 1,000,000. The water-based primer composition for removing paint exhibits the ability to easily peel off paint that has adhered and deposited, even in areas where paint removal is relatively difficult, such as corners and bends of coating equipment in a short time. Therefore, it is necessary to coat the film with a sufficient film thickness to every corner, so the higher the molecular weight, the better. The method for measuring the molecular weight of polystyrene sulfonic acid and its salt is not particularly limited and may be appropriately selected from known methods. For example, gel permeation chromatography (GPC method), viscosity method, light scattering Law.

  The polymer of the aqueous primer composition for peeling paints of the present invention can have the following formula (2) as a repeating structural unit in addition to the formula (1).

  In the formula, M is the same or different, and hydrogen, Li, Na, K, Cs and other alkali metals and ammonium ions, monoethanolalkanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanol 1 or more types chosen from alkanolamines, such as an amine, can be mentioned.

  Examples of the polymer having the formula (1) and the formula (2) as a repeating unit include maleic acid polystyrene sulfonate and fumaric acid polystyrene sulfonate. The order of the repeating units of Formula (1) and Formula (2) is not specified, and may be random or block.

  In the polymer used in the present invention, the repeating structural unit represented by the formula (1) is contained in an amount of 25% by mass to 100% by mass based on the monomer.

  In addition to the repeating structural unit represented by the formula (1) and the repeating structural unit represented by the formula (2), the polymer used in the present invention is styrene within a range that does not impair the properties as an aqueous primer for removing paints. , Ethylene, propylene, vinyl acetate, vinyl chloride, vinyl alcohol, acrylic acid, methacrylic acid, acrylic acid ester (methyl ester, ethyl ester, etc.), methacrylic acid ester (methyl ester, ethyl ester, etc.), acrylamide, methacrylamide, etc. Other repeating structural units derived from the monomer may be included. The other repeating structural unit is preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 10% by mass or less, particularly preferably 5% by mass or less, and preferably 1% by mass or less based on the monomer based on the whole polymer. Is most preferred. In addition, these other repeating structural units may be combined with the repeating structural unit of Formula (1), and may be combined with the repeating structural unit of Formula (1) and Formula (2).

  In polystyrene sulfonic acid maleic acid and salts thereof, the mass ratio (maleinization rate) of maleic acid sites in the total weight of the polymer is 25 wt% to 75 wt%. Since iron is often used as the material for the coating equipment and the water-soluble primer tank for removing the coating, it is more preferable that the maleinization rate is lower in view of the corrosion and liquid deterioration due to elution of iron ions.

  The polymer of the aqueous primer composition for peeling paint according to the present invention may further contain a repeating unit derived from styrene or the like.

  The polymer having a repeating structural unit represented by the formula (1) of the present invention, preferably polystyrene sulfonic acid and a salt thereof or polystyrene sulfonic acid maleic acid and a salt thereof are commercially available or commercially available. It can be synthesized using a monomer as a raw material. Each component can be produced by a conventionally known general method.

  The aqueous primer composition for peeling paint according to the present invention comprises a polymer having a repeating structural unit represented by the formula (1) of the present invention, preferably polystyrene sulfonic acid and salt thereof or polystyrene sulfonic acid maleic acid and salt thereof) and the balance. Contains water.

  The proportion of the polymer having a repeating structural unit represented by the formula (1) and the salt thereof in the aqueous primer composition for peeling paint according to the present invention is not particularly limited, but is usually 1 to 50% by mass, Preferably it is 1-20 mass%, More preferably, it is 2-10 mass%.

  The aqueous primer composition for peeling paint according to the present invention is a surfactant other than the components, such as a hydrophilicity imparting agent, a nonionic surfactant, a leveling agent, an antibacterial agent, an antifungal agent, a thickener, a rust preventive agent, etc. Antifoam additive may be included. As these additives, conventionally known additives can be used. The compounding amount of these additives is usually about 0 to 10% by mass, preferably about 0.5 to 5% by mass, and more preferably about 1 to 3% by mass.

  The aqueous primer composition for peeling paint according to the present invention is preliminarily treated on the surface of coating tools before coating the coating tools. After adhering the water-based primer for removing the paint of the present invention to the surface of the painting equipment by dipping, spraying, showering, etc., the water is evaporated by natural drying or heat drying (for example, 60 to 90 ° C.). As a result, a film is formed on the surface of the painting equipment.

  Examples of the painting tools include hangers, jigs, and tools such as slats, painting devices, painting robot arms, painting booth inner walls, floor members, and the like.

  The thickness of the film is not particularly limited, but is usually 10 to 100 μm, preferably 15 to 50 μm. If the thickness of the film is less than 10 μm, the peeling effect cannot be obtained and the paint cannot be completely removed. Further, when the thickness is 100 μm or more, the drying property is deteriorated, the removability of the coating itself is deteriorated, or the coating is peeled off when a physical impact is applied in a state where the coating is adhered and deposited on the coating of the aqueous primer composition for coating peeling ( The occurrence of defective products due to chipping) becomes a problem.

  When coating equipment having a primer coating on the surface is used in the painting process according to each purpose, a coating film is formed on the surface of the primer coating, and the coating equipment is a solution containing a paint release agent. It is subjected to a cleaning process. The paint remover may be appropriately selected from the paint removers conventionally used in the field according to the kind of attached paint, the attached thickness, the material of the object to be treated, and the like. Examples of paint removers include water, aqueous alkali solutions such as sodium hydroxide, potassium hydroxide, sodium polyphosphate, and sodium carbonate, aromatic alcohols such as benzyl alcohol, aromatic ethers such as phenylmethyl ether, and alkanols such as ethanolamine. Examples include glycols such as amine, ethylene glycol and propylene glycol, alkoxyaryls such as DMF, DMSO, glycol ether, glycol acetate and anisole, and aryl sulfonates such as sodium benzenesulfonate and sodium toluenesulfonate.

  The paint remover may be either of an alkaline type (more than pH 8) or a neutral type (pH 6-8).

  As a method of using the release agent, it is used by dipping, and the release temperature is 5 to 100 ° C, preferably 50 to 90 ° C, more preferably 70 to 90 ° C.

The aqueous primer composition for peeling paint according to the present invention can be applied to general uncured coating films adhered to coating instruments.

  The invention is further illustrated by the following examples.

Peeling performance evaluation [Examples 1 to 10 and Comparative Examples 1 to 6]
The water-based primer compositions for peeling paints of Examples and Comparative Examples were used for the tests by adjusting various non-volatile components by adding water to various commercially available polystyrene sulfonic acids and salts thereof or polystyrene sulfonic acid maleic acid and salts thereof.

  Cold strip steel plate (SPCC-SD) flat plate test piece (70mm x 50mm x 0.8mm) is degreased with acetone, then polished with # 240 sandpaper, and prepared according to the formulation shown in Table 1. Soaked in.

  The test piece was pulled up and dried (60 ° C., 60 minutes) to form a film on the surface. This test piece was dipped in a paint for painting automobile parts (white paint OP-70-P manufactured by Kansai Paint Co., Ltd.) and applied to the paint by lifting, and then baked (140 ° C., 30 minutes). After baking, it was immersed in a water-soluble paint remover heated to 50 ° C., and the time until the paint was completely removed was measured. The results of peel performance evaluation are shown in Tables 1 and 2, and the composition of the water-soluble paint remover is shown in Table 3.

  From Table 1, it can be seen that when the primer composition of the present invention is used, even when a neutral release agent that is generally difficult to peel off is used, the peeling time of the paint or coating film is short, and it has sufficient peeling performance.

Claims (5)

Characterized in that it contains the polymer and its salts and water having a repeating structural unit represented by the following formula (1), is applied prior to application of the paint, to remove the paint by using a paint stripper Aqueous composition.

[Wherein, M represents any of hydrogen, alkali metal, ammonium ion, and alkanolamine. ] Set composition as claimed in claim 1, characterized by having a repeating structural unit represented by the polymer further following formula (2).

[Wherein, M represents any of hydrogen, alkali metal, ammonium ion, and alkanolamine. ] Set composition as claimed in claim 1 or 2 polymer and the concentration of the salt is 1 to 50 mass%. It said polymer polystyrene sulfonic acid or a salt thereof, or a polystyrene sulfonic acid maleic acid or a salt thereof, set composition as claimed in any one of claims 1 to 3. Coated painted instrumentation before painting the set composition as claimed in any one of claims 1 to 4, the peeling method of coating removing cured or uncured paint from painted instrumentation using paint stripper after painting .