JP2007084695A - Lubricant composition for fin, fin and heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricant composition which can improve the drying properties of volatile press oils and reduce the stay of the volatile press oils on the surfaces of the fins. <P>SOLUTION: This lubricant composition for fins comprises a lubricant component (I) having surface tension of ≥50 [mN/m] in a 1 mass% aqueous solution and a hydrophilic resin (II) prepared by partially neutralizing the acid groups of a ternary copolymer comprising a carboxy group-having monomer (a1), a hydroxy group-having monomer (a2) and an amide group-having monomer (a3). Thereby, the drying properties of volatile press oils can be improved, and the stay of the volatile press oils on the surfaces of fins can be reduced. No problem is caused in an air tightness test by the water immersion method of a heat exchanger. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lubricant composition suitably used for the surface of a fin of a heat exchanger.

  Fins used in heat exchangers such as room air conditioners and industrial heat exchangers are generally made of aluminum or an aluminum alloy (hereinafter referred to as “aluminum”) having a hydrophilic coating film formed on the surface and further coated with a lubricant. It is manufactured by a method in which a volatile press oil is applied to the material and then press-molded. The obtained fin is made into a heat exchanger through a process such as welding of a copper pipe. The volatile press oil generally has a flash point of about 50 to 90 ° C. and contains a low polarity paraffinic oil as a base oil.

The heat exchanger thus manufactured is usually subjected to a heating and drying step for volatilizing the volatile press oil used at the time of press molding, for example, under conditions of about 140 to 160 ° C. × 4 to 6 minutes, An air tightness test is performed to check whether the welded portion of the copper tube has air tightness.
As the airtightness test method, for example, as described in paragraph 0013 of Patent Document 1, paragraph 0013 of Patent Document 2, etc., air or nitrogen gas is introduced into the copper tube while the heat exchanger is submerged in the measured pressure water. There is a method (water dipping method) in which a gas such as is supplied and the presence or absence of bubbles at that time is visually determined.
Japanese Patent Laid-Open No. 10-306996 Japanese Patent Laid-Open No. 10-306997

  However, in such a water immersion method, when the heat exchanger is submerged in the pressure detection water, the pressure detection water becomes cloudy, and it may be impossible to visually determine the presence or absence of bubbles.

The present inventor examined the cause of the white water of the test water when the heat exchanger was submerged in the test water, and found that some component in the volatile press oil used when press-molding the aluminum material. It has been found that the fact that the water remains on the surface of the fin without being sufficiently volatilized in the heat-drying step is the cause of the white water of the detected pressure water. Specifically, the components in the remaining volatile press oil and the surfactant components contained in the lubricant applied to the surface of the aluminum material are emulsified to form micelles, and the pressure is detected. The water may be clouded. Recently, fins have also become smaller with the miniaturization of heat exchangers, and fin pitch tends to be narrowed for the purpose of improving COP (energy consumption efficiency). It is thought that it becomes difficult to volatilize.
Therefore, the present inventor has intensively studied a method for making it difficult for volatile press oil to remain on the surface of the fin. As a result, by using a specific lubricant, the drying property of the volatile press oil applied on the lubricant is improved, and the volatile press oil is less likely to remain on the surface of the fin. As a result, the present invention has been completed.

The lubricant composition for fins of the present invention comprises a monomer (a1) having a carboxyl group in the lubricant component (I) having a surface tension of 50 [mN / m] or more when a 1% by mass aqueous solution is formed, The hydrophilic resin (II) obtained by partially neutralizing the acid group of the ternary copolymer comprising the monomer (a2) having a hydroxyl group and the monomer (a3) having an amide group was blended. Features.
The lubricant component (I) is polyethylene glycol having a molecular weight of 2000 to 8000, and the molecular weight of the hydrophilic resin (II) is preferably 50000 to 200000.
It is preferable that 1 to 25 parts by mass of the hydrophilic resin (II) is blended with respect to 100 parts by mass of the lubricant component (I).
The fin of the present invention is characterized in that a lubricating coating film comprising the above-described fin lubricant composition is formed and formed by press working.
The heat exchanger according to the present invention includes the fin.

  According to the fin lubricant composition of the present invention, the drying property of the volatile press oil can be improved, so that the remaining volatile press oil on the fin surface can be reduced. Therefore, the airtightness test by the water immersion method of the heat exchanger provided with such fins can be carried out without any problem.

Hereinafter, the present invention will be described in detail.
The fin lubricant composition of the present invention comprises a lubricant component (I) and a hydrophilic resin (II). The lubricant component (I) is a 1% by weight aqueous solution. Use a surface tension of 50 [mN / m] or more. When using a 1% by weight aqueous solution having a surface tension of less than 50 [mN / m], the drying property of the volatile press oil is not sufficiently improved even when the obtained lubricant composition for fins is used. . Furthermore, those having a surface tension of less than 50 [mN / m] when made into a 1% by mass aqueous solution have a low polarity, and thus tend to form volatile press oil and micelles.

  Suitable examples of the lubricant component (I) include polyethylene glycol, polyglycerin ester, starch paste, and the like. Among these, the surface tension when a 1% by mass aqueous solution is 50 [mN / m] or more is used. Although a thing can be used, especially polyethylene glycol is preferable from the point which has the outstanding lubricity. Moreover, as polyethyleneglycol, that whose molecular weight is 2000-8000 is preferable. When it is less than 2000, the coating film strength tends to decrease when the obtained fin lubricant composition is formed into a coating film. On the other hand, when it exceeds 8000, the solubility in water is extremely lowered, and it becomes difficult to prepare a lubricant composition for fins using water as a solvent.

The hydrophilic resin (II) is a ternary copolymer comprising a monomer (a1) having a carboxyl group, a monomer (a2) having a hydroxyl group, and a monomer (a3) having an amide group. The acid group is partially neutralized and has high polarity.
As the monomer (a1) having a carboxyl group, for example, a carboxylic acid such as (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid, etc. Examples include alkyl alcohol half-esters having a chain or side chain, and these are used singly or in combination. Of these, acrylic acid, methacrylic acid, maleic acid, and half esters of saturated alkyl alcohols having 1 to 2 carbon atoms of maleic acid are used, and acrylic acid is particularly preferable.

  Examples of the monomer (a2) having a hydroxy group include 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl methacrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, and 3-hydroxypropyl acrylate. Hydroxy (meth) acrylic acid esters such as 3-hydroxybutyl methacrylate, 3-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 4-hydroxybutyl acrylate, 2,3-dihydroxypropyl methacrylate, 2,3-dihydroxypropyl acrylate And hydrides such as 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether or 4-hydroxybutyl vinyl ether Alkoxyalkyl vinyl ether. Of these, 2-hydroxyethyl acrylate, 2,3-dihydroxypropyl acrylate, 2-hydroxyethyl vinyl ether, and 2-hydroxyethyl methacrylate are preferably used, and 2-hydroxyethyl methacrylate is particularly preferable.

  Examples of the monomer (a3) having an amide group include acrylamide, methacrylamide, N-methylol acrylamide, diacetone acrylamide and the like. Of these, acrylamide, N-methylolacrylamide, and the like are preferable, and acrylamide is particularly preferable.

The monomer (a1) having such a carboxyl group, the monomer (a2) having a hydroxyl group, and the monomer (a3) having an amide group are polymerized to form a terpolymer, The hydrophilic resin (II) is obtained by partially neutralizing the acid group.
The polymerization method for preparing the ternary copolymer is not particularly limited, and may be performed by a normal polymerization reaction in an aqueous medium. At that time, a normal polymerization initiator that can be used for the polymerization reaction of the vinyl monomer can be used, and examples thereof include water-soluble ammonium persulfate and potassium persulfate, 2,2′-azobis { 2-Methyl-N- [2- (1-hydroxybutyl)]-propionamide}, 2,2′-azobis [N- (2-carboxyethyl) -2-methyl-propyne amidine and the like can be preferably used. In addition, it is preferable that such a polymerization initiator is used in 0.1-10 mass parts with respect to 100 mass parts of total amounts of said monomer (a1)-(a3), especially 0. The range of 0.5-6 mass parts is preferable. Although there is no restriction | limiting in particular as temperature of a polymerization reaction, For example, it carries out at 60-65 degreeC.

  Further, the mass ratio of the monomers (a1) to (a3) when preparing the terpolymer is not particularly limited, but preferably (a1) :( a2) :( a3) = 40. -80: 5-20: 10-40. When the mass ratio of the monomers (a1) to (a3) is within such a range, the drying property of the press oil can be sufficiently enhanced. More preferably, (a1) :( a2) :( a3) = 50 to 70:10 to 15:20 to 30. Furthermore, (a1) :( a2) :( a3) is within the above range, (a1) is more than (a2) and (a3), and (a2) is (a3) or less. The case is more preferred.

  For partial neutralization of the terpolymer, basic compounds such as ammonia and alkali metal hydroxides can be used, and the alkali metal hydroxide is preferably sodium hydroxide or potassium hydroxide. May be used alone or in combination. Moreover, as a grade of partial neutralization, the grade which neutralizes about 5 to 20% in the acid group of a ternary copolymer is preferable.

  The number average molecular weight of the hydrophilic resin (A) thus prepared is not particularly limited, but is preferably 50,000 to 200,000. If it is less than 50000, even if it uses the obtained lubricant composition for fins, there exists a tendency for the drying property of volatile press oil not to fully improve. On the other hand, when it exceeds 200,000, solubility in water is extremely lowered, and it becomes difficult to prepare a lubricant composition for fins using water as a solvent.

  The lubricant composition for fins of the present invention is obtained by blending the above-described lubricant component (I) with a hydrophilic resin (II). Although there is no restriction | limiting in these compounding ratios, it is preferable that hydrophilic resin (II) is 1-25 mass parts with respect to 100 mass parts of lubricant components (I) in conversion of solid content. If the hydrophilic resin (II) is less than 1 part by mass, the drying property of the volatile press oil tends not to be sufficiently improved even if the obtained fin lubricant composition is used, whereas it exceeds 25 parts by mass. Then, the lubricity of the fin lubricant composition is insufficient, and the action as a lubricant tends to be insufficient.

Further, the fin lubricant composition can be obtained by mixing the lubricant component (I), the hydrophilic resin (II), and an additive that is added as necessary. Usually, a solvent such as water is used. Dissolved or uniformly dispersed and used in a state adjusted to an appropriate viscosity for coating.
Such a fin lubricant composition is usually applied to the surface of an aluminum material on which a hydrophilic coating film has been formed in advance by appropriate means such as brushing, dipping, spraying, electrostatic coating, or roll coater. , Held at about 80 to 250 ° C. for about 5 to 90 seconds and dried to form a lubricating coating. Although there is no restriction | limiting in particular in the thickness of a lubricating coating film, it is 0.01-2 micrometers, Preferably it is 0.05-1.0 micrometer.

  Fins can be produced by applying volatile press oil on the thus formed lubricating coating and press-molding the aluminum material. The obtained fin is made into a heat exchanger through a process such as welding of a copper pipe.

  In the fin thus obtained, as described above, a lubricating coating film composed of a lubricant composition for fins in which a specific hydrophilic resin (II) is blended with a specific lubricant component (I). Further, since the volatile press oil is applied, the drying property of the volatile press oil is improved. Therefore, by subjecting the heat exchanger equipped with the fin to a conventional heat drying process (for example, 140 to 160 ° C. × 4 to 6 minutes), the drying proceeds sufficiently, and the volatile press oil remains on the surface of the fin. It becomes difficult. As a result, even if a heat exchanger equipped with such fins is subjected to an airtightness test by a water immersion method, the detected water is less likely to become cloudy, and an airtightness test by the water immersion method can be performed without any problem. . By improving the drying property of volatile press oil in this way, even in the case of heat exchangers with recent small fins that tend to be more difficult to dry and fins with narrow pitches, it is sufficient to use the water immersion method. An airtightness test can be performed.

  As described above, it is not clear why the volatile press oil is applied to the lubricating coating film of the fin lubricant composition of the present invention to improve the drying property of the volatile press oil. The lubricating coating film has a higher polarity than a coating film made of a lubricant containing a conventionally used surfactant. Therefore, it is inferred that the drying property of the volatile press oil is enhanced by repulsion with the volatile press oil having a low polarity.

Hereinafter, the present invention will be specifically described with reference to examples.
[Example 1]
Acrylic acid (AA) as a monomer (a1) having a carboxyl group, 2-hydroxyethyl methacrylate (HEMA) as a monomer (a2) having a hydroxyl group, and a monomer having an amide group Using 100% of acrylamide (AAm) as (a3) at the mass ratio shown in Table 1, and adding a total of 100 g to ion-exchanged water so that the concentration of these solids (monomer concentration) is 10% by volume. Furthermore, 0.6 g of potassium persulfate was added as a polymerization initiator, stirred in a nitrogen atmosphere, and reacted at a polymerization temperature of 60 to 65 ° C. for 8 hours to obtain a dispersion containing a terpolymer.
Subsequently, the acid group of the ternary copolymer was partially neutralized with potassium hydroxide to obtain a dispersion of hydrophilic resin (II). The degree of partial neutralization was such that about 10% of the acid groups of the terpolymer were neutralized.
On the other hand, polyethylene glycol (PEG) whose molecular weight and surface tension when made into a 1% by mass aqueous solution are values shown in Table 2 is used as the lubricant component (I), and is put in a container equipped with a stirrer together with ion-exchanged water. A PEG aqueous solution having a solid content concentration of 4.0% by mass was prepared.
The thus obtained aqueous solution of PEG and the previously obtained dispersion of hydrophilic resin (II) are mixed so as to have the mass ratio (in terms of solid content) shown in Table 2 to obtain a lubricant composition for fins. Got.
And apply | coated the obtained lubricant composition for fins on the surface of the aluminum material in which the hydrophilic coating film which consists of water glass-type hydrophilic resin previously was formed, and hold | maintained for 30 second at the temperature of 120 degreeC, Dried. The formed lubricating coating film had a thickness of 0.2 μm.

The following evaluation was carried out using the aluminum material on which the lubricating coating film was formed as a sample.
(1) Evaluation of white turbidity 50 samples having a size of 100 mm × 100 mm were placed in 500 mL pure water and shaken for 60 seconds, and the absorbance of the obtained test water (wavelength 660 nm, absorption cell thickness 50 mm) was measured. The results are shown in Table 1. The abbreviations in the table indicate the following contents.
○: Less than 0.05 Δ: 0.05 or more and less than 0.10 ×: 0.10 or more

(2) Dryability of press oil A sample of 50 cm x 10 cm in size is dipped in volatile press oil (manufactured by NNUL Brinkants), then it is stood and dried for 10 minutes, and further dried by heating at 150 ° C for 5 minutes. did. Thereafter, the residual amount of volatile press oil was measured. The results are shown in Table 1. The abbreviations in the table indicate the following contents.
○: Less than 0.05 g Δ: 0.05 g or more and less than 0.10 g ×: 0.10 g or more

(3) Lubricity Lubricity was evaluated by a Bowden test. A 9/32 inch diameter steel ball with a load of 200 g was placed on the surface of the lubricating coating surface of the sample placed on the sample table, and the dynamic friction coefficient was measured when reciprocating 10 times.
The results are shown in Table 1. The abbreviations in the table indicate the following contents.
○: 0.05 or more and less than 0.10 Δ: 0.10 or more and less than 0.15 ×: 0.15 or more

[Examples 2 to 24, Comparative Examples 1 to 6]
The mass ratio of acrylic acid (AA), methacrylic acid-2-hydroxyethyl (HEMA), and acrylamide (AAm) is the mass ratio shown in Table 1, except that the amount of the polymerization initiator used is changed as appropriate. Similarly, a liquid containing a terpolymer was obtained, and then a partial neutralization step was performed in the same manner to obtain a dispersion of hydrophilic resin (II).
On the other hand, an aqueous PEG solution was prepared in the same manner as in Example 1 except that the lubricant component (I) having the molecular weight and surface tension shown in Table 2 was used.
And the dispersion liquid of hydrophilic resin (II) and PEG aqueous solution are mixed so that it may become the mass ratio (solid content conversion) of Table 2, the lubricant composition for fins is obtained, and a later process and various evaluation are also carried out. The same operation as in Example 1 was performed.

From the above results, in each of the examples, the drying property of the press oil was excellent, and as a result, the evaluation of white turbidity was also good. Also, the lubricity was good.
On the other hand, in each comparative example, the drying property and white turbidity evaluation of the press oil were poor, and were not suitable as a lubricant composition for fins.

Claims (5)

In the lubricant component (I) having a surface tension of 50 [mN / m] or more when the 1% by mass aqueous solution is prepared,
The acid group of the ternary copolymer comprising the monomer (a1) having a carboxyl group, the monomer (a2) having a hydroxyl group, and the monomer (a3) having an amide group was partially neutralized. A fin lubricant composition comprising a hydrophilic resin (II).   2. The fin lubricant composition according to claim 1, wherein the lubricant component (I) is polyethylene glycol having a molecular weight of 2000 to 8000, and the molecular weight of the hydrophilic resin (II) is 50000 to 200000. .   The lubricant composition for fins according to claim 1 or 2, wherein 1 to 25 parts by mass of the hydrophilic resin (II) is blended with respect to 100 parts by mass of the lubricant component (I). .   A fin, wherein a lubricating coating film comprising the lubricant composition for fins according to any one of claims 1 to 3 is formed and formed by press working. A heat exchanger comprising the fin according to claim 4.