JPWO2018124025A1 - Polyester resin-coated metal plate and polyester film for press-molded metal plate coating - Google Patents

Abstract

Disclosed is a resin-coated metal plate having excellent film-removability after press molding. A polyester resin-coated metal plate of the present invention includes a metal plate to be press-molded and a polyester resin layer coated on the metal plate, and the polyester resin layer has a sulfonic acid as a hydrophilic group. It contains a salt and has a glass transition temperature (Tg) of less than 100 ° C. [Selection] Figure 1

Description

  The present invention relates to an organic resin coating applied on a metal plate, and more particularly to a polyester resin-coated metal plate having excellent film-removability after press molding, and a coating polyester film that can be laminated on the metal plate.

  For example, automobiles that are indispensable as modern transportation means are manufactured by press-forming steel plates. In such press molding, formability is improved by applying a lubricant made of resin, oil or fat on a steel sheet (see Patent Document 1 and Patent Document 2).

  In recent years, due to demands for lower fuel consumption and the like, the shift from steel plates to other materials such as aluminum has been progressing as materials for automobiles. However, for example, aluminum has a lower formability than a steel plate, and therefore, press forming or the like becomes difficult in a relatively complicated structure such as a frame of a motorcycle or a door panel of a four-wheel vehicle.

  As press molding for such difficult-to-process materials, processing by warm press molding has begun to attract attention. In the warm press forming, in order to reduce the load during press working and improve the workability of aluminum itself, the press working mold is heated to a high temperature of about 200 to 300 ° C., for example. (Patent Document 3).

  On the other hand, in Patent Document 4, it was discovered that the residue of the lubricating film after the warm press forming affects the post-treatment, and after removing the residue appropriately, after the surface treatment such as anodizing treatment or painting. It has been proposed that processing can be performed without problems.

Japanese Patent Laid-Open No. 55-38840 JP 2010-197017 A Japanese Patent Laying-Open No. 2015-54422 International Publication No. 2007/023967

However, it cannot be said that the conventional techniques including the above-described Patent Documents 1 to 4 satisfy the market needs, and there are problems described below.
First, in Patent Documents 1 to 3, since the wax is contained as the lubricating film, there is a concern that the working environment is deteriorated due to volatilization of the film components with respect to the heating during press molding. Furthermore, when the lubricating film is altered by heating, a lubricating film residue may be generated after molding, and it cannot be denied that it becomes a serious defect in a post-treatment process such as painting.

  The influence of the lubricant film residue on the quality is enormous, and according to Patent Document 4, it can be said that the influence is suppressed. However, in Patent Document 4, there is room for improvement from the viewpoint of improving efficiency because residues are removed under sufficient conditions such as treatment for 10 minutes using ultrasonic waves in a temperature environment of 70 ° C. In other words, for example in the manufacture of automobiles, reduction of production cost is also an important factor that increases competitiveness, and it is important how the lubricant film can be removed (defilming) without generating residue. .

  The present invention has been made in view of solving such problems, and provides a polyester resin-coated metal plate having excellent film-removability after press molding, and a polyester film for coating that can be laminated to a metal plate to be press-molded The purpose is to do.

  In order to solve the above problems, a polyester resin-coated metal plate according to an embodiment of the present invention includes (1) a metal plate and a polyester resin layer coated on the metal plate, and the polyester resin layer is It is characterized by containing a sulfonate as a hydrophilic group and having a glass transition temperature (Tg) of less than 100 ° C.

In the polyester resin-coated metal plate according to (1), (2) the sulfonate is preferably 4 mol% or more based on the total dicarboxylic acid component in the polyester resin layer.
In the polyester resin-coated metal sheet according to (1) or (2), it is preferable that (3) the sulfonate is a sodium salt.
In the polyester resin-coated metal plate according to (3), (4) the sodium salt is preferably sodium 5-sulfoisophthalate.
The polyester resin-coated metal plate according to any one of (1) to (4) further includes (5) an organic resin layer coated on the polyester resin layer, It is preferable that acrylic and colloidal silica are contained.

  In order to solve the above-mentioned problem, a polyester film according to an embodiment of the present invention is (6) a polyester film for covering a metal sheet to be press-molded, containing a sulfonate as a hydrophilic group, and glass The transition temperature (Tg) is less than 100 ° C., and the metal plate can be removed by alkali degreasing after being press-molded.

In addition, in the polyester film for coating | cover as described in said (6), it is preferable that (7) the said sulfonate is 4 mol% or more with respect to all the dicarboxylic acid components in the said polyester film.
Moreover, in the polyester film for coating | cover as described in said (6) or (7), it is preferable that (8) said sulfonate is a sodium salt.
Moreover, in the polyester film for coating | cover as described in said (8), it is preferable that (9) the said sodium salt is 5-sulfoisophthalic-acid sodium salt.

  According to the present invention, it is possible to realize a polyester resin film having excellent film-removability, and, for example, when applied to a metal plate for press forming, it is possible to achieve both excellent productivity and high film-removability at a high level. It becomes possible.

It is sectional drawing which showed typically the structure of the polyester resin coating metal plate 10 which concerns on this embodiment. It is sectional drawing which showed typically the structure of the polyester resin coating metal plate 20 which concerns on the other example of this embodiment.

<< First Embodiment >>
<Polyester resin-coated metal plate>
Hereinafter, an embodiment for carrying out the present invention will be described.
As shown in FIG. 1, a polyester resin-coated metal plate 10 according to this embodiment includes a base material 1 and a polyester resin layer 2. This polyester resin-coated metal plate 10 is suitable for, for example, warm press molding, and exhibits good film-removability in removing a film after press molding.
Hereafter, each component is explained in full detail about the polyester resin coating metal plate 10 which concerns on this embodiment.

[Base material]
As the base material 1 serving as a base of the polyester resin-coated metal plate 10, a metal plate containing aluminum, iron, copper, titanium, magnesium, and an alloy of the above metals such as an aluminum alloy, a steel plate, and stainless steel is used.
There is no restriction | limiting in particular about the thickness of the metal plate as this base material 1, The thickness of the base material 1 can take a various value with the use.

[Polyester resin coating (layer)]
The polyester resin layer 2 of this embodiment is coated on the substrate 1. In FIG. 1, the polyester resin layer 2 is coated on both the front and back surfaces of the substrate 1, but the polyester resin layer 2 may be coated only on one side.
As the polyvalent carboxylic acid component constituting the polyester resin layer 2, aromatic, aliphatic, and alicyclic dicarboxylic acids, trivalent or higher polyvalent carboxylic acids, or ester derivatives thereof may be used. The polyester resin layer 2 is preferably composed mainly of, for example, a dicarboxylic acid and a diol.

  As aromatic dicarboxylic acids, terephthalic acid, isophthalic acid, orthophthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-dimethylterephthalic acid, biphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2-bis Phenoxyethane-p, p′-dicarboxylic acid, phenylindanedicarboxylic acid and the like may be used as appropriate.

  Further, aliphatic and alicyclic dicarboxylic acids include succinic acid, adipic acid, sebacic acid, azelaic acid, dimer acid, dodecanedioic acid, 1,3-cyclopentanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1 , 4-cyclohexanedicarboxylic acid or the like, or ester-forming derivatives thereof may be used.

  On the other hand, as the glycol component constituting the polyester resin layer 2, ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1 , 5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 2,4-dimethyl-2-ethyl Hexane-1,3-diol, neopentyl glycol, 2-ethyl-2-butyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-2-isobutyl-1, 3-propanediol, 3-methyl-1,5-pentanediol 2,2,4-trimethyl-1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl- 1,3-cyclobutanediol, 4,4′-thiodiphenol, bisphenol A, 4,4′-methylenediphenol, 4,4 ′-(2-norbornylidene) diphenol, 4,4′-dihydroxybiphenol, o -, M-, and p-dihydroxybenzene, 4,4'-isopropylidenephenol, 4,4'-isopropylidenediol, cyclopentane-1,2-diol, cyclohexane-1,2-diol, cyclohexane-1, 4-diol or the like may be used.

  Examples of the polyester resin layer 2 include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene isophthalate, ethylene terephthalate, butylene terephthalate, 1,4 cyclohexanedimethyl terephthalate, ethylene isophthalate, butylene isophthalate. , A polyester resin obtained by polymerizing at least one of ethylene naphthalate, ethylene adipate, and butylene adipate. Moreover, you may apply resin formed by blending 2 or more types of these polyester resins.

In particular, the polyester resin layer 2 of the present embodiment contains a sulfonate as a hydrophilic group. Such a sulfonate is preferably at least one of a sodium salt, a lithium salt, and a potassium salt.
From the viewpoint of procurement cost and versatility, a sodium salt is preferable as the sulfonate, and sodium sodium 5-sulfoisophthalate is most preferable among the sodium salts as described later. In addition, even when the sulfonate is a sodium salt, it does not inhibit other salts from being contained in a trace amount in addition to the sodium salt.

  Furthermore, the polyester resin layer 2 of the present embodiment is characterized in that the glass transition temperature (Tg) is less than 100 ° C. This is because when the glass transition temperature (Tg) exceeds 100 ° C., it becomes difficult to dissolve in the treatment liquid at the time of alkaline degreasing, and it is difficult to perform an appropriate film removal treatment in view of cost, work environment, and the like. More specifically, when the glass transition temperature (Tg) exceeds 100 ° C., the bath temperature of the treatment liquid at the time of film removal is increased or the polyester resin layer 2 is used in order to appropriately dissolve in the alkaline degreasing treatment liquid. The content of the sulfonate must be increased. When the bath temperature of the processing liquid at the time of film removal is increased, the processing liquid volatilizes and the working environment may be deteriorated. Further, for example, when a large amount of sulfonate such as SIP is put in the polyester resin layer 2, there is a concern that the film forming property of the polyester resin layer 2 on the base material 1 may be reduced or the strength of the film may be reduced. It is not preferable because it is high.

  The glass transition temperature (Tg) of the polyester resin layer 2 is preferably 0 ° C. to 100 ° C., and 25 ° C. to 64 ° C. when the polyester resin layer 2 contains 5-sulfoisophthalic acid sodium salt. It is preferable.

Moreover, it is preferable that content (mol%) of the sulfonate contained in the polyester resin layer 2 is 4 mol% or more when the total dicarboxylic acid component is 100 mol%. This is because, when the sulfonate is less than 4 mol% with respect to the total dicarboxylic acid component, the film removal property particularly after warm press molding is deteriorated.
In addition, when the total dicarboxylic acid component is 100 mol%, the content (mol%) of the sulfonate described above is more preferably 6 to 20 mol%, and more preferably 10 to 17 mol%. In particular, when the above-described sulfonate is sodium 5-sulfoisophthalate, the content (mol%) is 6 to 17 mol% when the total dicarboxylic acid component is 100 mol%. More preferably, it is more preferably 10 to 17 mol%.

Moreover, it is preferable that the molecular weight (number average) of the polyester resin layer 2 is 20000 or less. This is because when the molecular weight of the polyester resin layer 2 exceeds 20000, the polymerization time may be increased due to the increase in the molecular weight, resulting in a disadvantage that productivity is lowered. In addition, if the molecular weight is too high, it may be difficult to dissolve in the treatment solution during alkaline degreasing. For proper dissolution, the bath temperature during film removal is increased or the sulfonic acid in the polyester resin layer 2 is increased. This is because there may be a problem that the salt content must be increased. If the bath temperature of the processing solution at the time of film removal is set to a high temperature, the processing solution may volatilize and the working environment may deteriorate. In addition, for example, if a large amount of sulfonate such as SIP is put in the polyester resin layer 2, there is a concern that the film forming property of the polyester resin layer 2 on the base material 1 may be deteriorated or the coating itself may be deteriorated, and further, the cost. It is not preferable because it is high.
In addition, it is more preferable that the molecular weight of the polyester resin layer 2 is 10000-17000.

  The thickness of the polyester resin layer 2 is not particularly limited, and various values may be applied. However, from the viewpoint of cost, 0.1 to 10 μm is preferable. -5 μm is more preferable, and 0.5 to 2.0 μm is the most desirable in consideration of productivity.

Moreover, it is desirable that the polyester resin layer 2 does not contain an acrylic component, such as not being acrylic-modified. It is because the film removal property from the base material 1 after press molding will fall because the polyester resin layer 2 contains the acrylic component which is excellent in alkali resistance.
Moreover, it is desirable that the polyester resin layer 2 does not contain wax. This is because if the polyester resin layer 2 contains a wax, the wax component is volatilized by heating during press molding, and an odor is generated. From such a viewpoint, the wax contained in the polyester resin layer 2 is preferably less than 5 wt%, more preferably less than 1 wt%, and still more preferably less than 0.1 wt%.

<Polyester film>
The polyester resin layer 2 of the present embodiment is not limited to the form formed on the substrate 1 (metal plate) described above as the surface treatment layer, and may be a film that can be laminated on the metal plate described above. .
That is, the polyester film of the present embodiment is suitable for, for example, a coating application to a metal plate to be press-molded (particularly warm press-molding), contains a sulfonate as a hydrophilic group, and has a glass transition temperature (Tg). It is characterized by being less than 100 ° C. Furthermore, the polyester film of this embodiment can be removed by alkaline degreasing after the base material 1 (metal plate) is warm-pressed.

There is no particular limitation on the method for producing such a polyester film. For example, a coating film containing the polyester resin of the present invention is applied on a base substrate such as Teflon (registered trademark) and dried to form a polyester film. Later, it can be obtained by peeling it from the base substrate.
In addition, if the polyester film after the said application | coating drying can be peeled, there will be no restriction | limiting in particular in the kind of base base material, You may apply a well-known various material as a base base material.
Moreover, since the characteristics (a kind, molecular weight, Tg, content, etc.) regarding the sulfonate contained in a polyester film are the same as that of the polyester resin layer 2 mentioned above, the description is abbreviate | omitted.

<< Second Embodiment >>
Next, a polyester resin-coated metal plate 20 according to another example of the present embodiment is shown in FIG.
In addition, about 2nd Embodiment demonstrated below, the structure which has the same effect as 1st Embodiment mentioned already attaches | subjects the same number, and also the description is abbreviate | omitted suitably.

  As shown in FIG. 2, the polyester resin-coated metal plate 20 of the second embodiment includes a base material 1, a polyester resin layer 2, and a functional layer 3. In FIG. 2, the polyester resin layer 2 and the functional layer 3 are formed on both the front and back sides of the substrate 1, but it is sufficient that these layers are formed on at least one side of the substrate 1, and the other Only the polyester resin layer 2 may be formed on this side, and neither the polyester resin layer 2 nor the functional layer 3 may be formed.

As described above, the polyester resin-coated metal plate 20 according to the present embodiment is mainly characterized in that the functional layer 3 is further laminated on the polyester resin-coated metal plate 10 of the first embodiment.
For the functional layer 3 of the present embodiment, for example, an organic resin film shown below is applied for the purpose of improving warm moldability. Such an organic resin film is preferably a water-based resin, that is, a water-soluble or water-dispersible resin, and is formed by modifying a water-based urethane resin, polyester resin, acrylic resin, epoxy resin, or these organic resins. An acrylic modified polyester resin, a phenyl silicon modified acrylic resin, and the like are preferable. These organic resins may be used alone or in combination of two or more.

  Since the organic resin is preferably used at a temperature exceeding 150 ° C. as the processing temperature during warm press processing, it is preferable to use an organic resin having excellent heat resistance.

These organic resins may be applied alone on the polyester resin layer 2 to form a film. However, in order to improve molding processability and corrosion resistance, the following substances may be included in the organic resin and used. .
That is, for example, when the functional layer 3 contains a silane coupling agent, the adhesiveness to the lower layer, particularly the adhesiveness during the molding process, is remarkably improved. Silane coupling agents are classified according to the type of functional group such as vinyl, epoxy, styryl, methacryloxy, acryloxy, amino, ureido, chloropropyl, mercapto and isocyanate. It can be used effectively. This is presumably because the silane coupling agent has excellent binding properties, that is, adhesion to most resins.
The silane coupling agent is preferably contained in the functional layer 3 at 5 wt% or less, more preferably 1 wt% or less. This is because even if the content exceeds 5 wt%, the effect of improving adhesion is saturated and is not economically advantageous.

  Further, for example, when the functional layer 3 contains colloidal silica, the hardness of the organic resin film is improved, the scratch resistance is improved, and the corrosion resistance is also improved. Such colloidal silica is preferably contained in the functional layer 3 at, for example, 70 wt% or less. This is because if the content exceeds 70 wt%, the organic resin film becomes too hard and the workability deteriorates, and the functional layer 3 is likely to crack during the molding process. In addition, when it is preferable that the functional layer 3 is soft, the content of colloidal silica is more preferably 55 wt% or less, and more preferably 50 wt% or less.

  Furthermore, for example, by incorporating a lubricant into the functional layer 3, molding processability is improved. Lubricants include higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, calcium salts of these higher fatty acids, aluminum salts, zinc salts, barium salts, magnesium salts, higher fatty acid esters thereof, polyethylene wax, Polyolefin wax such as polypropylene wax, fluorine-based wax such as polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, and polyvinyl fluoride, inorganic powder such as graphite, molybdenum disulfide, and boron nitride can be used. . These lubricants are preferably contained in the functional layer 3 at 20 wt% or less. This is because if the content exceeds 20 wt%, the adhesion deteriorates even during molding.

  Furthermore, for example, heat resistance is improved by adding a metal alkoxide to the functional layer 3. Examples of metal alkoxides include boron, aluminum, titanium, vanadium, manganese, iron, cobalt, copper, yttrium, zirconium, niobium, lanthanum, cerium, tantalum, and tungsten alkoxides. Among them, titanium-based alkoxides are preferable. Can be used. These metal alkoxides are preferably contained in the functional layer 3 at 10 wt% or less. This is because if the content exceeds 10 wt%, the moldability deteriorates. The silane coupling agent, colloidal silica, lubricant, and metal alkoxide may be contained singly in the functional layer 3, respectively, but may be contained in two or more.

In addition, from the viewpoint of improving moldability in warm press molding, an organic resin film containing an acrylic component and colloidal silica is particularly preferably used as the functional layer 3.
In this case, the thickness of the functional layer 3 is not particularly limited. However, if the functional layer 3 is too thick, there is a risk that the film-removing property of the lower polyester resin layer 2 may be lowered. The thickness is preferably 0.2 to 5.0 μm, and more preferably 0.2 to 4.0 μm in consideration of cost.
In this embodiment, since the functional layer 3 is formed on the polyester resin layer 2, the polyester resin layer 2 is dissolved in the film removal step, so that the functional layer 3 is not dissolved but is removed from the substrate 1. The polyester resin layer 2 and the functional layer 3 can be removed. Therefore, in this embodiment, the solubility of the functional layer 3 is not particularly limited.

<Example>
EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

<Example 1>
First, a coating liquid to be applied to the substrate 1 was prepared.
Specifically, ethylene glycol is used as the glycol component constituting the polyester resin, isophthalic acid is used as the polyvalent carboxylic acid component, and 5-sulfoisophthalic acid sodium salt (hereinafter also referred to as “SIP”) is used as the hydrophilic group. A polyester resin copolymerized so that the SIP content in the dicarboxylic acid component is in the ratio shown in Table 1 was used.
At this time, the Tg of the prepared resin was 25 ° C. and the molecular weight was 15000. Tg was measured with a known differential thermal scanning calorimeter.
In addition, although the polyester resin of Example 1 does not contain any of an organic solvent, a wax, and an acrylic component, it may be appropriately included within a range that does not affect the film removal property.

Next, this polyester resin was dispersed in an aqueous solvent to prepare a coating solution of the water-dispersed polyester resin. And the component analysis was performed with respect to the resin component extracted by drying from this coating-film liquid by the H-NMR spectroscopy (proton-Nuclear Magnetic Resonance spectroscopy) using JEOL JMN EX-400. The amount of SIP at this time was 6 mol% with respect to the total dicarboxylic acid component in the polyester resin.
In the examples described later, SIP is used as the hydrophilic group. However, in the present invention, the hydrophilic group only needs to be dissolved in the state of -SO3- in the coating solution, so that the sulfonic acid is not limited to the sulfonic acid Na salt. Similar principles apply to other sulfonates such as Li salts. In other words, it can be easily estimated that the technical scope of the present invention is not limited to the sulfonic acid Na salt used above but can be extended to other sulfonic acid salts.

A polyester resin layer 2 was formed on the substrate 1 using the obtained coating solution so that the thickness after drying was 6 μm. The drying conditions were intended to evaporate water, and the temperature of the substrate 1 was 110 ° C.
At this time, an aluminum plate having a thickness of 0.8 mm was used as the substrate 1. In addition, you may perform surface treatment, such as washing | cleaning suitably, for the surface of an aluminum plate previously by a well-known method.

The obtained polyester resin-coated metal plate was heated for 10 minutes at 200 ° C., 250 ° C. and 300 ° C., respectively, assuming warm press molding.
Then, after heating, an aqueous solution of an alkaline degreasing agent (EC90 manufactured by Nippon Paint Co., Ltd.) is used for immersion treatment (combined with stirrer stirring at 500 rpm) at 50 ° C. for 2 minutes, which is a relatively difficult condition for film dissolution. The film removal treatment was performed. In addition to this, film removal treatment was similarly performed on a polyester resin-coated metal plate that was not subjected to heating assuming warm press molding. In addition, pH in the aqueous solution of the said alkaline degreasing agent was 11.2.

[Evaluation of film removal]
After the degreasing, the film removal property was evaluated in the following manner.
That is, the film removal property evaluation in the examples uses a fluorescent X-ray apparatus (ZSX100e manufactured by Rigaku), and when a film is formed, the strength of C (carbon) (C-Kα ray, net strength) is detected high. Therefore, the presence or absence of residue was judged from the C intensity. For simplicity, for example, when the base material 1 is Al, the C strength of the base material 1 is about 0.3 to 0.6 kcps. It can be judged that there is no residue.

On the other hand, in this example, in order to confirm whether there is no residue in more detail, the film removal property was evaluated using the following calculation.
That is,
IA: C strength of base material before coating liquid coating (after degreasing, de-smudge (pickling))
IB: C strength after the coating liquid is applied to the substrate and further dried IC: When C strength is obtained after performing a film removal test after applying the heat history assumed for warm processing,
The film removal rate is expressed by (IB−IC + IA) / IB × 100 (%).

And when the film removal rate calculated | required by this calculation is the value shown below, it evaluates with 1-4, respectively.
1: 99.8% or more Complete film removal, no residue (Note that it may slightly exceed 100% depending on the error range derived from the substrate. Also, 99.8% or more and less than 100% are derived from the substrate. (Depending on the error range, it can be regarded as complete film removal. In view of the above, a value exceeding 99.8% to 100% was regarded as “1” evaluation.)
2: 80% or more and less than 99.8% 3: 20% or more and less than 80% 4: less than 20% (not removed)

  For example, in Example 1, the C strength IA of the base material 1 before coating the coating liquid is 0.5 kps, and the C strength IB after forming the polyester resin layer 2 by drying after coating the coating liquid is After heating for 10 minutes at 25 kcps and 200 ° C., the C strength IC after film removal treatment at 50 ° C. for 2 minutes was 0.5 kcps, and the film removal rate at this time was 100%. .

[Odor evaluation]
Further, in the heating process assuming warm press molding, the presence or absence of odor was evaluated according to the following criteria.
1: No odor 2: Odor 3: Strong odor

<Example 2>
The glycol component constituting the polyester resin is ethylene glycol and diethylene glycol, and the polyvalent carboxylic acid component is isophthalic acid, terephthalic acid, and SIP in the proportions shown in Table 1, the molecular weight is 17000, the Tg is 64 ° C., and the SIP amount is 10 mol. The same procedure as in Example 1 was performed except that the percentage was changed to%.

<Example 3>
The glycol component constituting the polyester resin is ethylene glycol and 1,4-cyclohexanedimethanol, the polyvalent carboxylic acid component is isophthalic acid and SIP in the proportions shown in Table 1, the molecular weight is 10,000, the Tg is 50 ° C., the SIP amount Was carried out in the same manner as in Example 1 except that the content was 17 mol%.

<Example 4>
Ethylene glycol and diethylene glycol are used for the glycol component constituting the polyester resin, and isophthalic acid, terephthalic acid and SIP are used for the polyvalent carboxylic acid component in the proportions shown in Table 1, the molecular weight is 15000, Tg is 45 ° C., and the SIP amount is 10 mol%. The procedure was the same as in Example 1 except that.

<Example 5>
The glycol component constituting the polyester resin is ethylene glycol and diethylene glycol, the polyvalent carboxylic acid component is isophthalic acid, terephthalic acid and SIP in the proportions shown in Table 1, the molecular weight is 15000, the Tg is 50 ° C., and the SIP amount is 16 mol%. The procedure was the same as in Example 1 except that.

<Example 6>
The same procedure as in Example 5 was performed except that oxidized high density polyethylene (PE) was added as a wax at a ratio of 1 wt%.

<Example 7>
The same procedure as in Example 5 was performed except that oxidized high density polyethylene (PE) was added as a wax at a rate of 10 wt%.

<Example 8>
The same procedure as in Example 5 was performed except that modified polyethylene was added at a rate of 10 wt% as a wax.

<Example 9>
First, ethylene glycol and diethylene glycol are used for the glycol component constituting the polyester resin, and isophthalic acid, terephthalic acid and SIP are used for the polyvalent carboxylic acid component in the ratios shown in Table 1, and the thickness of the polyester resin layer 2 after drying is 0. This was carried out in the same manner as in Example 1 except that the thickness was 0.8 μm, the molecular weight was 15000, the Tg was 50 ° C., and the SIP amount was 16 mol%.
Next, a functional layer 3 having a thickness of 0.4 μm was formed on the formed polyester resin layer 2. The functional layer 3 was an acrylic resin film containing 50 wt% colloidal silica (produced with 50 wt% acrylic and 50 wt% colloidal silica).
Thereafter, in the same manner as in Example 1, the obtained surface-treated metal plate was subjected to heat treatment assuming warm press forming, and further subjected to degreasing treatment to evaluate film removal and odor.

<Comparative Example 1>
Instead of the polyester resin 2 as in the example, a urethane resin was used as the thermoplastic resin formed on the substrate 1. The urethane resin was dispersed in a solvent containing NMP (N-methyl-2-pyrrolidone) (19%) as water (81%) and an organic solvent to prepare a coating solution.
And the urethane resin film was formed on the base material 1 using the prepared coating liquid so that the thickness after drying might be set to 6 micrometers.

The obtained urethane resin-coated metal plate was heated for 10 minutes at 200 ° C., 250 ° C., and 300 ° C., respectively, assuming warm press molding.
Then, after heating, an aqueous solution of an alkaline degreasing agent (EC90 manufactured by Nippon Paint Co., Ltd.) is used for immersion treatment (combined with stirrer stirring at 500 rpm) at 50 ° C. for 2 minutes, which is a relatively difficult condition for film dissolution. The film removal treatment was performed. In addition to this, degreasing was performed in the same manner on a urethane resin-coated metal plate that did not undergo heating assuming warm press molding.
Thereafter, the film removal property was evaluated in the same manner as in the Examples.

<Comparative Example 3>
It carried out similarly to the comparative example 1 except the ratio of the organic solvent in a coating-film liquid having been 8%.

<Comparative Example 3>
Ethylene glycol and 2,2-dimethyl-1,3-propanediol are used as the glycol component constituting the polyester resin, and isophthalic acid, terephthalic acid and SIP are used as the polyvalent carboxylic acid component in the proportions shown in Table 1, and the molecular weight is 15000. The same procedure as in Example 1 was conducted except that the Tg was 67 ° C., the SIP amount was 3 mol%, and the organic solvent was changed to buticerosolve and added at a ratio of 17%.

<Comparative Example 4>
Ethylene glycol and diethylene glycol are used as the glycol component constituting the polyester resin, naphthalene dicarboxylic acid and SIP are used as the polyvalent carboxylic acid component in the proportions shown in Table 1, the molecular weight is 25000, the Tg is 100 ° C., and the SIP amount is 6 mol%. The procedure was the same as in Example 1 except that.

<Comparative Example 5>
A PET (polyethylene terephthalate) resin film (molecular weight: 3000, Tg: 30 ° C.) having a carboxy group (—COOH) as a hydrophilic group was formed on the substrate 1 so as to have a thickness of 6 μm.
The obtained PET resin-coated metal plate was heated for 10 minutes at 200 ° C., 250 ° C. and 300 ° C., respectively, assuming warm press molding.
Then, after heating, an aqueous solution of an alkaline degreasing agent (EC90 manufactured by Nippon Paint Co., Ltd.) is used for immersion treatment (combined with stirrer stirring at 500 rpm) at 50 ° C. for 2 minutes, which is a relatively difficult condition for film dissolution. The film removal treatment was performed. In addition to this, degreasing was performed in the same manner on a PET resin-coated metal plate that did not undergo heating assuming warm press molding.
Thereafter, the film removal property was evaluated in the same manner as in Example 1.

<Comparative Example 6>
The same procedure as in Comparative Example 1 was performed except that the thickness of the urethane resin coating after drying was 1 μm and the functional layer 3 having a thickness of 1 μm was formed on the urethane resin. The functional layer 3 in Comparative Example 6 was an acrylic resin film containing 50 wt% colloidal silica (produced with 50 wt% acrylic and 50 wt% colloidal silica).

<Comparative Example 7>
An aluminum plate having a thickness of 0.8 mm was used as the substrate 1, and the functional layer 3 was formed on the substrate 1 so that the thickness after drying was 1 μm. The functional layer 3 in Comparative Example 7 was an acrylic resin film containing 50 wt% colloidal silica (produced with 50 wt% acrylic and 50 wt% colloidal silica).
Thereafter, in the same manner as in Example 1, the obtained surface-treated metal plate was subjected to heat treatment assuming warm press forming, and further subjected to degreasing treatment to evaluate film removal properties.

<Comparative Example 8>
It carried out similarly to the comparative example 4 except the thickness of the polyester resin layer 2 having been 3 micrometers.

  Table 1 shows characteristic values such as thickness and components of the resin-coated metal plate in each of the examples and comparative examples obtained as described above. Further, Table 2 shows the results of film removal evaluation and odor evaluation in each of Examples and Comparative Examples.

  In Table 1, “IA” indicates isophthalic acid, “TA” indicates terephthalic acid, “NDCA” indicates naphthalenedicarboxylic acid, and “SIP” indicates sodium 5-sulfoisophthalic acid.

  Moreover, the component of the polyester resin layer 2 of Table 1 has described the ratio of the dicarboxylic acid component when a dicarboxylic acid component is 100 mol% and an alcohol component is 100 mol%, respectively. Among these, the SIP amount in Table 1 particularly indicates the SIP amount in all dicarboxylic acid components.

As is apparent from the above, in each of the examples of the present invention, in the film removal after heating within the temperature assumed in the warm press molding, excellent film removal property of complete film removal was shown.
On the other hand, in the comparative example, the film removal property is insufficient within the temperature assumed in the warm press molding, and it is expected that a serious problem occurs in the post-treatment process.

  It should be noted that the above-described embodiment and each example can be variously modified without departing from the spirit of the present invention.

  As described above, the polyester resin-coated metal plate and the polyester resin-coated film of the present invention exhibit excellent film-removing properties by, for example, warm press molding, and can be applied to a wide range of industries including automobiles. Is possible.

DESCRIPTION OF SYMBOLS 1 Base material 2 Polyester resin layer 3 Functional layer 10, 20 Polyester resin coating metal plate

Claims (9)

A metal plate,
A polyester resin layer coated on the metal plate,
The polyester resin-coated metal plate, wherein the polyester resin layer contains a sulfonate as a hydrophilic group and has a glass transition temperature (Tg) of less than 100 ° C.   2. The polyester resin-coated metal sheet according to claim 1, wherein the sulfonate is 4 mol% or more based on the total dicarboxylic acid component in the polyester resin layer.   The polyester resin-coated metal plate according to claim 1 or 2, wherein the sulfonate is a sodium salt.   The polyester resin-coated metal sheet according to claim 3, wherein the sodium salt is 5-sulfoisophthalic acid sodium salt. Further comprising an organic resin layer coated on the polyester resin layer,
The polyester resin-coated metal plate according to any one of claims 1 to 4, wherein the organic resin layer contains acrylic and colloidal silica. It is a polyester film for covering a metal plate to be press-formed,
Containing sulfonates as hydrophilic groups,
The glass transition temperature (Tg) is less than 100 ° C., and
A polyester film characterized in that it can be removed by alkaline degreasing after the metal plate is press-molded.   The polyester film according to claim 6, wherein the sulfonate is 4 mol% or more based on the total dicarboxylic acid component in the polyester film.   The polyester film according to claim 6 or 7, wherein the sulfonate is a sodium salt.   The polyester film according to claim 8, wherein the sodium salt is 5-sulfoisophthalic acid sodium salt.