JPS6094169A - Curing device for coating film - Google Patents

Abstract

PURPOSE:To cure coating film continuously in a short time and safely in a device for curing coating film contg. isocyanate groups with amine by locating a curing chamber at a lower position than an inlet/outlet port for charging and discharging of coated material. CONSTITUTION:A charging passage 2a having a charging port 5 for charging coated articles 10' into a curing chamber 1 and a discharging passage 2b having a discharging port 6 for discharging articles 10' after contacting the articles with amine are provided to a curing chamber 1 in order to enable continuous treatment. An air feeding duct 16 having a spraying port 16a at the bottom wall and an air feeding duct 17 having many fine holes 17a on both side walls are also provided to the curing chamber 1. The amine generated in a curing vapor generating device 3 is introduced into the curing chamber through the ducts 16, 17, and the curing vapor is sprayed to the moving articles revolving by itself. In this stage, leakage of the amine is prevented because the inlet and outlet ports are installed at lower positions than the charging and discharging ports 5, 6 of the curing chamber 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating curing device, and more particularly to a coating curing device for curing a coating film containing a free isocyanate group-containing preprimer in an amine atmosphere.

Traditionally, the formation of coatings presents various problems in terms of thermal energy, pollution, and productivity. Most commonly used industrially. In the coating film forming method, after a basic article is coated, the coated article is carried into a baking furnace and the coating film is baked at a high temperature. This baking requires a large amount of thermal energy, and an expensive 411 gas treatment system is required to remove harmful components such as 16 solvent and paint tar generated during baking of the paint film from the exhaust gas. In addition, in the case of painting woodwork, etc., where the paint film cannot be baked at high temperatures, the paint film must be cured by air drying, which requires an extremely long time for the paint film to harden, and during that time, Strict control is required to prevent dirt from landing on the paint film.

In recent years, methods for drying paint films that are unpleasant to cure due to heat have been proposed, and Japanese Patent Publication No. 13038/1983 describes
A method for forming a dry film is described, which consists in applying a vehicle comprising a prepolymer containing free isocyanate groups onto a substrate and then treating this vehicle with an agent consisting of ammonia or an amine in the vapor phase. ing.

However, this ammonia or amine has a very strong odor, and even a very small amount of it causes discomfort to humans. Therefore, when such a method is adopted, the airtightness of the device becomes an important issue.

The present invention relates to an apparatus for carrying out the above method, and in particular, an apparatus for efficiently baking or curing a coating film by the above method using an amine continuously and in a substantially closed system. Regarding.

That is, an object of the present invention is to provide an apparatus for continuously curing a coating film containing free^1F incyanate groups with an amine in a closed system.

Another object of the present invention is that it is possible to cure a coating film in an extremely short time without the need for baking operations at high temperatures, and as a result, the equipment is small and the productivity is high. To provide a coating film curing device that is easy to maintain.

Still another object of the present invention is to cure the paint film in an extremely short time even on articles for which it has been difficult to bake the paint film by heat, such as wood products, hydraulic equipment, and articles with extremely large heat capacity. Our goal is to provide a device that makes it possible.

According to the invention, there is provided an apparatus for curing a coating film by contacting a bed layer containing a prepolymer having 13) L isocyane-1 groups with an amine in the gas phase, comprising: a curing chamber; a carrying-in passageway having a carrying-in port for carrying coated articles into the curing chamber and a carrying-out passage having a carrying-out port for carrying them out; and a steam generator for generating an air flow containing vapor of the , a circulation system that supplies air θ1 from the steam generator to the curing chamber and circulates the gas after contact with the coated article to the steam generator, and an inlet and outlet to the curing chamber for leakage of amine vapor. There is provided a coating film curing device comprising: a mechanism for sealing so as not to occur; the curing chamber is located at a C lower blade portion compared to the carrying inlet and the carrying out outlet.

The present invention will be explained in detail below with reference to the accompanying drawings. Figure 1 is a side cross-sectional view showing an outline of the coating film curing apparatus of the present invention, and Figure 2 is a cross-sectional view of the curing apparatus of Figure 1. Shows the AI @ surface diagram.

1 and 2, the coating film curing apparatus of the present invention generally includes a curing chamber 1, a carry-in passage 2α having a carry-in port 5, and a carry-out passage 2b having a carry-in port 6. , a steam generator 6 , a curing airflow circulation system 4 , and a sealing mechanism 7 provided at an inlet 5 and an outlet 6 .

Furthermore, FIG. 6 is a diagram showing an example of a six-part planar arrangement in which this coating film curing device is combined with an attached painting room and a post-curing room.

In the specific example shown in FIG. 6, a coating chamber 8 is disposed upstream of the curing chamber 1, and a post-curing chamber 9 is disposed downstream of the curing chamber 10, and a transport system 100 is provided to pass through these. ing.

The coating room 8 supplies an article (substrate) 10 to be coated with
It is for applying a specific paint, that is, a paint containing a prepolymer containing free incyanate groups, and is provided with an inlet 11 into which a substrate 10 is introduced, similar to a normal simple paint booth.
and an outlet 12 through which the coated substrate is carried out, and a coating mechanism 16 such as a spray gun for applying the paint onto the substrate is provided on one side of the movement path of the substrate 1o.
Further, on the other side, an exhaust suction duct 15 is provided via a paint mist collection mechanism 14 such as a filter (if necessary).

The paint used in the apparatus of the present invention is a paint containing a prepolymer containing free isocyanate groups, and is cured by contact with a gaseous amine, which will be described in detail later. Suitable examples of such coatings include incyanate-terminated prepolymers, such as polyester polyols, polyether polyols, hydroxyl-containing acrylic resins, hydroxyl-containing vinyl resins, alkyd resins, polyamides,
Polyisocyanates, such as tolylene diisocyanate, hexamethylene diisocyanate,
The incyanate is reacted with cyclohexane diisocyanate or diphenylmethane diisocyanate and bonded to the skeleton of the oligomer or polymer through a urea bond, a urea bond, or the like. Of course, the above-mentioned oligomer or polymer reactive with the incyanate group and the polyincyanate may be reacted in advance or partially reacted in the form of a mixture. It may be a mixture of multiple types of resins. In summary, it should be understood that any coating material may be used for purposes of the present invention as long as it contains sufficient free incyanate groups to be cured with a gas phase amine.

Old fl: The degree of isocyanate group is generally resin content 1
The amount is preferably in the range of 10 to 5[]0 mmol, particularly 6 to 3001 mol per 0.00 g.

If this paint is a liquid with a viscosity suitable for painting,
It can be used as a solvent-free paint, or as a solution-type paint in which the prepolymer is diluted with a solvent. Of course, this paint contains components known in the art, such as pigments, plasticizers, surfactants, anti-sagging agents, rust inhibitors, etc., in known proportions. Suitable. A typical paint has a non-volatile content concentration of 20 to 100 parts by weight and a kinematic viscosity (Ford cup +4) of 15 to 150 seconds.

Substrates 1o to be coated include, in addition to substrates formed from ordinary steel plates or surface-treated steel plates, wooden products with heat-baked coatings, textile products, plastic products, hydraulic equipment products, and castings with a large heat capacity. You can list the products etc.
Particularly in the case of such substrates, the significant advantages of the present invention are achieved in that no thermal baking is necessary and the curing of the coating takes place quickly.

As the coating Ut913, a coating mechanism using a spray, for example; tlrJ: air spray gun, airless spray gun, rotary atomization type coating device, etc., including non-electrostatic type and electrostatic type, is suitably used. . Of course, other coating methods such as dip coating, roller coating, flow coating, etc. may also be employed depending on the type of substrate.

Returning again to FIGS. 1 and 2, the curing chamber 1 is for bringing the coated article 10' from the coating chamber 8 into contact with a gaseous amine to effect a curing reaction of the formed coating film. , in order to enable continuous processing, a carry-in passage 2cL having a carry-in port 5 for carrying the coated article 10' into the room, and a carrying-out passage 2cL having a carry-in port 6 for carrying out the article after contact with the amine. 2b, the coating film curing apparatus of the present invention has a curing chamber 1, in order to continuously and effectively cure the coating film within a short period of time.
, a curing amine vapor generation device 6, and a curing air flow circulation system 4 are provided in the relationship described in detail below.

First, the curing chamber 1 is equipped with an air supply duct 16 having a blowing port 16α on the bottom wall in order to evenly and uniformly supply a curing gas (airflow) containing amine to the coated article 10'. In addition, an air supply duct 17 having a large number of fins 17α is provided on both side walls, and a curing gas is sprayed onto the coated article 10' which moves while rotating.

These ducts 16, 17 are connected via a supply duct 18 to a curing steam generator B.

This curing steam generator generates amines in a gas phase in a curing chamber 1.
In the specific example shown in the drawings, curing vapor is generated by spraying amine into a carrier gas such as air or nitrogen fed by a fan 19 using a spray device 2o.

The curing chamber 1 has an exhaust duct 21 equipped with an exhaust port 21 cL.
is connected to the suction side of the 77n 19 via an exhaust duct 22 and, if necessary, a filtration and cleaning mechanism 26 such as a filter.

b −
1, an exhaust duct 22, a fan 19, a supply duct 18, and an air supply duct 16.17. This circulation system 4 can be provided with a curing gas heating unit 41+4 m (not shown) if necessary, and during the winter when the temperature drops, the temperature of the curing gas is kept at the same level as room temperature, that is, room temperature or The temperature can be maintained at about 60°C.

Further, an important feature of the present invention is that the curing chamber 1 is located at a lower portion than the entrance 5 and the exit 6. That is, in the present invention, amine is used as a curing agent, but the vapor of this amine is heavier than air, so by locating the curing chamber 1 in the lower part as described above, the amine vapor flows through the inlet 5 and the outlet 6. This effectively prevents leakage into the outside air.

In addition, an amine concentration detection mechanism 25a is provided in the curing steam supply port or in the curing chamber, and based on this detection signal,
Valve 2 of spray device 20 via concentration control circuit 25
6 and the amine in the curing chamber can always be set at a predetermined value.

V, ], The amines used in the present invention may be primary, digreen, or tertiary monoamines as well as polyvalent amines, such as methylamine, ethylamine, propylamine, diethylamine, triethylamine, piperidine, Examples include one or a combination of two or more of morpholine, piperazine, ethanolamine, jetanolamine, triethanolamine, cyclohexylamine, ethylenediamine, tetramethylethylenediamine, ethylenetriamine, and the like.

Although it is possible to make the amine exist in the form of undiluted vapor in the curing air stream, from the viewpoint of ease of operation and economic efficiency, it is preferable to add 100 to 10,000 ppη per liter of 50 to 50,000 ppm. It is desirable to contain it in the air stream at a concentration that is as follows.

In the present invention, furthermore, in order to completely prevent leakage of amine vapor, a sealing mechanism 7 (not indicated by 7) is provided at the entrance 5 of the entrance passage 2α and the exit 6 of the exit passage 2b. .

To explain the f (q configuration) of this sealing mechanism 7, with reference to FIG. 4 showing a BB sectional view of the device in FIG. It consists of a partition plate or flap 27 provided at the opening 5 and the exit 6 to allow passage of articles, and a circumferential intake port 29 connected to an intake duct 28.

That is, the partition plate or flap 27 is slidable or rotatable, so that passage openings of various shapes can be formed depending on the shape of the article 10' to be passed through. Adjusting the area effectively prevents amine vapor leakage.

Furthermore, an air seal is formed by suctioning the air near the inlet and outlet through the intake port 29, completely preventing amine vapor from leaking into the outside air.

Similarly, a part of the curing gas taken out from the air intake duct 28 and the exhaust duct 60 connected to the above-mentioned circulation system is passed through an exhaust treatment device 61 such as a scrubber, an adsorption device, a catalytic cracking device, etc. It can be released into the atmosphere as an odorless and harmless gas.

It goes without saying that the amines collected by the adsorption device can be recovered by desorption and used for the purpose of curing.

The time that the coated article is in contact with the amine varies depending on the type and thickness of the paint, the concentration in the curing gas, and the temperature, but generally speaking it is from 10 to 600 seconds, especially from 20 to 300 seconds.
An extremely short period of time, such as seconds, is sufficient.

According to the present invention, due to the above-described configuration, it is possible to continuously perform curing treatment of a coating film using an amine in a closed system without leaking harmful amine vapor to the outside. Moreover, by supplying the amine vapor as a current into a substantially sealed curing chamber and circulating this airflow through a steam generator, the contact between the coating film and the vapor is uniform, uniform, and intimate. By carrying out this process, *the curing reaction of the film is carried out effectively and within a short period of time. Also, by circulating the steam in a closed system, an economical curing process is possible while preventing loss of amine.

In the embodiment shown in FIG. 6, the coated article 10'', which has been in contact with the amine-containing curing gas in the curing chamber 1, is brought into contact with an air stream in the post-curing chamber 9.

In other words, a paint film that has just come into contact with amines will easily be scratched if you rub it with your fingernail, even if the hardening process is progressing. Contact with air is required for continued curing of the coating as measured by pencil hardness.

The post-curing chamber 9 has an inlet 62 and an outlet 3 for the coated articles 10''.
6, and a porous partition wall 64 is provided inside the tunnel along the movement path of the coated article. Air passage 65 through this partition wall 64
The air introduced into the passage 55 is blown onto the coated article 10'' through the partition wall 64, thereby promoting post-curing of the coating film. After being attached to the blowing fan 67 and coming into contact with the coating film in the edge curing chamber, the airflow is circulated from the exhaust duct 68 to the suction side of the fan 67 via the filtration and purification mechanism 69 and the heating mechanism 40.

Room temperature is sufficient for post-curing air, but in order to accelerate post-curing, it is advantageous to heat the air to a temperature of about 50°C.

In this embodiment, the transport mechanism 100 is arranged to pass sequentially through the coating chamber 8, the curing chamber 1, and the post-curing chamber 9 via a series of wheels or sprockets 41, and is continuously or Driven intermittently. In this specific example, the transport structure 100c is an endless overhead conveyor, and the articles 1o to be painted are 1.
The coated product 1oα is loaded onto the conveyor at the dipping position 46 and removed from the conveyor at the unloading position 44.

In the present invention, if it is acceptable to allow a sufficient amount of time for post-curing of the coating film, a method may be adopted in which the post-curing chamber 9 is omitted and the semi-cured coated article is left in the air. Further, it is also possible to separate from the coating room 8 and provide a conveyance system only in the coating film curing device.

According to the device of the invention as described above, the following significant advantages are additionally achieved. That is, although the furnace for drying and baking the paint film in the painting equipment consumes a huge amount of thermal energy, according to the present invention, baking at high temperatures is not necessary, resulting in significant energy savings. . In addition, it is possible to cure the coating film in a short time even on items for which it is difficult to bake the coating film at high temperatures.Furthermore, because the curing time is short, the equipment can be small-sized and production capacity can be significantly improved. . Furthermore, since it operates at or near room temperature, there is no risk of fire, and there is no need for cleaning like with conventional baking furnaces.
Maintenance is also easy.

In the above specific example, an example was shown in which the curing apparatus of the present invention was applied as a continuous type curing apparatus, but it is also possible to apply this curing apparatus as a δ17 batch type curing apparatus. In this case, the coating to be cured U::':
It is sufficient to provide a passageway in the upper blade of the curing chamber that can be used for both carrying in and (&, jlLf) of articles having It will be appreciated that the amine vapor is not passed through the upper passage and is more effectively prevented from exiting 4π.

[Brief explanation of drawings]

FIG. 1 is a side cross-sectional view showing the general outline of the curing apparatus of the present invention, FIG. 2 is an A-A IJJr side view of the apparatus of FIG.
The figure is a plan layout 6 showing the curing apparatus of Fig. 1 together with a coating 1 storage and post-curing chamber. 1 is the curing room, 2 (L is (general access channel h'i'I, 2b is the transport channel 11111.6 is the steam generator, 4 is the curing air circulation system, b is the transport 1), 6 is the general use port, 7 is the seal 134M, 8 is the painting room, 9 is the rear (ㅅ5 coating room, 10.10
', 10'' is a painted article (substrate), 10a is a painted product, 1
'5 is a coating mechanism, 16 and 17 are i air supply ducts, 18 is a supply duct, 19 is a fan, 20 is a spray device, 21
is an exhaust duct, 22 is an exhaust duct, 28 is an intake duct,
29 is a circumferential intake port, 31 is an air intake processing device, 100
indicate land-fed yarns, respectively. / 1 Kisho Dekijin Trinity Industries Co., Ltd. Fig. 4-r Itohashi Neyama j-1 3 - 噌 ■ (Method) % formula % 1. Indication of the incident [ ] / (Japanese Patent d1 Application No. 199931 No. 2, Name of the invention Paint film curing device 3, Relationship with the case of the person making the amendment Patent applicant 4, Agent address: 105 5, No date of amendment order 6, Subject of amendment (1) Specification No. 17 Add the following statement between lines 4 and 3 at the bottom of the page: II' Figure 4 shows a BB sectional view and a partial plan view of the device in Figure i1.

Claims (1)

[Claims] (1) An apparatus for curing a coating film containing a prepolymer having free isocyanate groups by contacting it with a gaseous amine, comprising a curing chamber and a coated article introduced into the curing chamber. A carry-in passageway having a carry-in port for the amine, a carry-out passage having a carry-out port for carrying out the amine, a steam generation device for generating an air flow to prevent amine vapor, and a steam generation device for directing the air flow from the steam generation device to the curing chamber. It consists of a circulation system for supplying the gas and circulating the gas after contact with the coated article to the steam generator, and a mechanism for closing the inlet and outlet to the curing chamber so that the amine vapor does not leak. A coating film curing device characterized in that the curing chamber is located at a lower portion than an inlet and an outlet.