JPH01254799A - Cleaning thinner for automatic coating machine - Google Patents

Abstract

PURPOSE:To obtain the subject thinner, improved in dispersibility between particles and permeability into fine gaps and suitable for cleaning foulings, such as pigment fixed to respective inner parts of valves, hoses, etc., in coating machines, by adding a surfactant to a thinner. CONSTITUTION:The objective thinner obtained by adding preferably a nonionic surfactant having 2-7 HLB (especially 3-4 HLB) or ionic surfactant having 14-18C (especially 16-18C) alkyl chain to a thinner. Furthermore, as preferred examples of the above-mentioned surfactant, oxyethylene alkylamino based surfactants are cited in electrostatic coating and N-alkyldimethyl-N-2- hydroxyethylammonium nitrate or dialkyl sulfosuccinates are cited as the surfactant in other coating methods.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cleaning thinner for self-painting surfaces that is used to clean stains caused by pigments stuck to the internal surfaces of valves, hoses, etc. in a painting machine. It is something.

[Conventional technology]

When painting with an #J painting surface, the pigment particles in the paint are not necessarily finely dispersed, but aggregate into so-called coarse particles, which accumulate and stick inside the painting machine, staining the painted surface, or when changing the paint. There are problems such as requiring a long time for cleaning, which hinders work.

In this way, coarse particles are generated by the agglomeration of pigment particles or their combination with polymerized resin or oil particles, and these particles adhere to the inside of the paint sprayer and develop into deposits and solidification. Therefore, in the past, the entire coating system was cleaned with thinners having a relatively high boiling point, not only when changing paints, but also when using the same paint, and color change valves and the like were dismantled and cleaned.

[Essential points to be solved by the invention] In other words, existing thinners lack the ability to dissolve the above-mentioned fixed substances, and also lack the ability to penetrate into the fine gaps between the adhering surfaces of coarse particles and the inner wall of the machine. Therefore, the effect of weakening the intermolecular force between the two and separating them was also insufficient. For this reason, removal of adhered substances within the coating machine has largely relied on mechanical cleaning using the flow energy of the thinner pumped into the machine, ie, pressure and frictional force. Therefore, in valves and the like having a complicated structure, a long cleaning operation using thinner is required to completely remove the stuck substances, that is, the contaminants.

Particularly when changing paints, it is necessary to thoroughly clean the inner surfaces of valves, hoses, bell tips, etc. However, in color change valves with complex shapes, the above contaminants adhere to the inner walls of the valves, so cleaning only with thinner is not recommended. cannot be said to be an efficient stripping or dissolving method.

Therefore, the present invention provides a thinner that can more efficiently clean large particles caused by the bonding of pigment particles adhering to the inside of a paint sprayer, or large particles caused by the bond between pigment particles and polymerized oils, fats, and resins. The purpose is to provide.

[Means for solving problems]

In order to achieve this objective, the present inventors added an appropriate surfactant according to the composition of the thinner, and further selected a thinner composition according to the properties of the active agent.
It has been found that increasing the permeability of thinner or preventing recombination of fine particles generated due to the disintegration of coarse particles (contamination), that is, increasing dispersibility, can be solved from an industrial technical point of view.

The cleaning thinner according to the present invention meets the conditions for the surfactant to dissolve in the ready-to-use thinner, which contains alcohols or cellosolves as operating solvents, esters as non-corrosive solvents, and hydrocarbon compounds. In addition, in consideration of safety, we use an activator with electrical resistance above a certain value if electrostatic coating is used, and an ionic activator with low electrical resistance if electrostatic coating is not used. It is characterized by the addition of

As a result of conducting various tests on the activator to be used, we found that it has good solubility in thinner, increased permeability into the pores between the generated particles and the adhering surface, and cost. Oxyethylene alkylamine surfactants are used as low conductivity surfactants with favorable behavior, and N-alkyldimethyl- as cationic surfactants are used as ionic surfactants when coating methods other than electrostatic coating are used. N-2 hydroxyethylammonium nitrate has been found to be preferred, as well as succinic acid dialkyl ester sulfonate as anionic activator. In the former case, the number of moles of oxyethylene group -(C11□CH,O)n is 6 to
7, and the number of carbon atoms in the hydrophobic group alkyl chain is 14 to
It has been confirmed that 18 is advantageous, and in the case of ionic activators, the total number of carbon atoms in each alkyl group is preferably 14 to 18.

[Effect]

By cleaning the inside of a painting machine with thinner containing such an activator, an interface is formed around pigment particles that remain on the inside of the machine and begin to enlarge, or agglomerated particles of oil, fat, resin, etc. The active agent orients to form micelles,
Gives a repulsive effect between particles and suppresses their agglomeration.

On the other hand, this thinner easily penetrates into the slits on the particle adhesion surface and into the inside of the particles themselves, and furthermore, with the addition of the mechanical peeling and diffusion effect due to the kinetic energy of the press-fitted thinner itself, the particles can be fragmented or peeled off. It is believed that these particles will be able to pass smoothly through the complex valve structure.

However, if the activator added to the thinner is nonionic, the ratio of hydrophilic groups to lipophilic groups (hereinafter referred to as HLB value) in the molecule is in the range of 2 to 7, and in the case of ionic activators. The number of carbon atoms in all the alkyl groups in the molecule varies from 14 to 18, but this is due to the ratio between the operating solvent and the non-thinner solvent that make up the thinner.

The particularly preferable range for the surfactant in the present invention is HI-B IIH of the nonionic surfactant from 3 to
4. Its molecular weight is 800-1600, and the number of carbon atoms in all the alkyl groups in the ionic activator molecule is 16-18.
However, it is considered advantageous to follow the values shown in Table 4-1 or Table 4-2, respectively.

〔Example] Next, the present invention will be explained based on Examples and Comparative Examples.

First, a normal painting process will be explained with reference to the drawings.

The paint passes through the regulator 1, three-way cock 2, pump 3, color change valve (CCV 14, trigger dump valve 5), and is sprayed out from the bell tip 6. When the trigger dump valve 5 is closed (spraying is interrupted), the paint is sprayed out from the bell tip 6. It is returned through a conduit 7 communicating with the change valve 4 and circulated.

On the other hand, when cleaning when changing the paint, the cleaning thinner replaces the paint, and the above-mentioned spraying process is followed, and the color change valve 4, trigger dump valve 5, which has a complicated structure. For the bell tip 6, a new cleaning thinner is separately supplied to the color change valve 4, and these complicated structures are cleaned.When the trigger dump valve 5 is closed, the return conduit 7, the three-way cock 2, The thinner is circulated through the pump 3.

Based on the above work steps, cleaning tests were conducted according to the following flow using various cleaning thinners as examples of the present invention and comparative examples according to the prior art.

Repeat 1. White paint spraying 5 seconds 21 Interval time 5 seconds return 3. Cleaning with thinner 1
1.7 seconds 4. Paint replacement time 2 minutes 20
5. Spray clear paint 5 seconds, 61 intervals
The spraying of each paint for 5 seconds is 2,500 CC cleaning air pressure 4.5 ATM cleaning thinner 140 cm Outside the CC cleaning test is shown in Table 1. Tests were carried out using thinners according to the formulations of Example 1 according to the invention and Comparative Examples shown in Table 2.

The results are shown in Table 3.

l-Up-1 Thinner formulation 1 of Example 1): (Lioxyethylene valmityl 7min HLB
= 3 Molecular Weight = 1600 Comparison of effects of thinner formulation in Comparative Example 1 As shown in the table above, the thinner according to the present invention gave almost complete results in cleaning the interior of the paint sprayer in 33 minutes.

Salmon 1 The test method, working fluid specifications, and thinner composition were the same as in Example 1, except that the surfactant used was replaced with a cationic one.

The thinner formulation is shown in Table 1-2, and the effect comparison is shown in Table 3-2.

Thinner formulation of Example 2 2) 2 N-lauryl 2-hydroxyethyl dimethyl 1-1 ammonium nitrate alkyl group (CxH
y) X number = 16 IL varnish effect It was demonstrated that the same effect as in Comparative Example 1 can be obtained with the ionic activator.

Next, Table 4-1 shows the quantitative relationship between the lipophilic group-hydrophilic group ratio (HLB) of the activator used and the polarity and non-corrosiveness of the solvent.

Table 4-2 shows the quantitative relationship between the number of carbon atoms in the alkyl chain in the ionic surfactant molecule used and the polar and non-polar solvent.

Hoshi U-E [Effects of the Invention] As described above, the automatic painting machine cleaning thinner according to the present invention improves the dispersibility between the five particles and the permeability into fine gaps due to the addition of a surfactant. The improved cleaning effect can greatly contribute to the overall painting process, such as eliminating contamination on the painted surface and shortening the cleaning time when changing paints.

In particular, if the LB value or the number of carbon atoms in the alkyl group in the molecule is selected optimally depending on the type of additive activator, the effect will be greater than 5.

[Brief explanation of the drawing]

The figure shows a schematic configuration of an automatic coating machine to which an embodiment of the present invention is applied. 2... Three-way cock 3... Pump 4... Color change valve 5... Trigger dump valve 6... Bell tip 7... ...Return conduit agent Masaharu Fukutome, patent attorney

Claims (3)

[Claims] (1) A thinner for cleaning dirt stuck to the inner wall of an automatic coating machine, characterized in that it contains a surfactant. (2) The thinner according to claim 1, wherein the surfactant is nonionic and has a hydrophilic group-lipophilic group ratio (HLB) in the molecule of 2 to 7. (3) The thinner according to claim 1, wherein the surfactant is ionic and has 14 to 18 carbon atoms in the alkyl chain in its molecule.