JP2012152723A - Production method of integrated molding by extrusion coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating method which carries out surface coating with a thermosetting coating composition simultaneously with extrusion molding for an extruded molding of metal.SOLUTION: The production method of a molding, which has a coating layer on the outer periphery of an extrusion-molded core part, has a step of supplying an extrusion molding member to an extruder equipped with an extrusion molding die and a coating die, and forms the extrusion-molded core part by an extrusion molding method; a step of supplying the thermosetting coating composition with viscosity of 500-50,000 mPa s at 25°C to the coating die; and a step of curing the thermosetting coating composition, supplied to the outer periphery of the extrusion-molded core part, by heat.

Description

  The present invention relates to a method for producing a molded body in which extrusion molding and surface coating are integrated.

  Extruded products used for automobiles, home appliances, building materials, etc. are used for the purpose of adding added value such as decorativeness, or improving the weather resistance and corrosion resistance to extend the product life. It has been widely practiced to paint the surface.

  Also disclosed is a method of coating with a synthetic resin simultaneously with extrusion molding. For example, in Patent Document 1, as a method for producing a synthetic resin product with a core material, a synthetic resin containing a core material by lamination molding and / or extrusion molding with a synthetic resin using a metal core material having a resin adhesive applied to the surface. A method characterized by obtaining a product is disclosed. However, in such a method, since it is necessary to apply the adhesive to the core in advance, the manufacturing is complicated and there is a problem in productivity. The following method has been proposed as a method not using the adhesive.

  For example, Patent Document 2 discloses a metal core having a predetermined thickness dimension, a width dimension, a longitudinal dimension, a uniform cross section in the longitudinal direction, and a corrugated plate shape as a manufacturing method of a building plate material. A method of manufacturing a building plate including a material and a resin including the core, the core having a corrugated shape having a uniform cross section in the longitudinal direction while conveying the metal strip in the longitudinal direction The first step of continuously forming the resin molding, the second step of continuously forming the resin molding including the core material by the resin extrusion molding method, and the resin molding formed in the second step for each predetermined length And a third step of cutting to obtain a unit plate material. Specifically, composite extrusion molding (coextrusion molding) is performed on the surface of a corrugated core material having a thickness of about 0.3 to 1.0 mm together with a resin raw material. However, with such a method, the productivity is certainly improved, but since the synthetic resin is directly coated on the metal core material, the adhesive force between the metal core material and the synthetic resin is insufficient and strong. When subjected to an impact, there was a problem of cracking and peeling. The synthetic resin is a thermoplastic resin that can be extruded.

  Patent Document 3 includes an aluminum shape and a resin shape obtained by integrally molding a soft coating material on a hard channel-shaped base material with engaging claws protruding at both ends. By forming a recess in the material, a latching part is formed on the lip of the engaging claw of the resin shape member when it falls down, and a slope is formed on the engaging part that hangs on the latching part at a clearance angle. There is disclosed a resin-decorated aluminum profile characterized in that a resin profile is detachably attached to a profile without an adhesive. As the resin shape, thermoplastic resins such as PVC, ABS, and AAS are disclosed. However, since this method also mechanically joins the synthetic resin to the metal core as it is, the adhesive strength between the metal core and the synthetic resin is insufficient, and there is a problem of cracking and peeling when subjected to a strong impact. was there.

  Patent Document 4 discloses a building member in which the surface of an aluminum core is covered with a synthetic resin layer. In this building member, the core material and the coating layer are integrated by integral extrusion. In this method, a coating layer made of a synthetic resin is formed on a part or all of the outer surface of the aluminum core material along the longitudinal direction of the core material, and at least the outer surface of the core material is coated. The layer forming region has a groove having a depth of 0.03 to 1.0 mm along the longitudinal direction. As the coating layer made of a synthetic resin, polyester-based and other thermoplastic resins are disclosed. However, this method also provides a groove on the surface of the aluminum core material and physically joins the synthetic resin, so the adhesive force between the aluminum core material and the synthetic resin is insufficient, and when a strong impact is received There was a problem of cracking and peeling.

  Patent Document 5 is composed of an aluminum core and a synthetic resin layer covering the sash constituting member having a generally complicated cross-sectional shape. This synthetic resin layer is coated on the surface of the core material by integral extrusion molding along the shape of the core material. For this reason, it is unnecessary to configure the synthetic resin layer in a complicated shape that can be physically attached to and detached from the core material, or to apply an adhesive in advance on the surface of the core material. As the synthetic resin layer, an extrudable thermoplastic resin is disclosed. However, in this method, since the synthetic resin is physically bonded to the aluminum core as it is, the adhesive force between the aluminum core and the synthetic resin is insufficient, and there is a problem of cracking and peeling when subjected to a strong impact. It was.

JP-A-62-13315 JP 2003-13543 A JP 2003-105945 A JP 2007-175949 A JP 2009-203778 A JP-A-8-206729 JP 2010-99727 A

  In the prior art, each of the surface coating layers is made of a thermoplastic resin. However, the thermoplastic resin has poor heat resistance, and the synthetic resin layer is softened under a high temperature environment, and easily becomes indented or scratched to reduce the commercial value. Moreover, the extruded core material and the synthetic resin as the surface coating layer are not chemically bonded but physically bonded, and there is a problem that the synthetic resin layer is cracked or peeled off by impact in a low temperature environment. .

  Then, this invention makes it a subject to provide the coating method which performs surface coating with a thermosetting coating composition simultaneously with extrusion molding with respect to the metal extrusion molding without the above-mentioned problem.

  In order to solve the above-mentioned problems, the present invention provides a coating die for surface coating at the tip of a molding die when extrusion molding a metal such as aluminum, aluminum alloy, magnesium or magnesium alloy, and is extruded. A method of continuously coating the surface of the molded body to form a coating film is provided.

That is, in accordance with the present invention, supplying an extrusion molding member to an extrusion molding machine provided with an extrusion molding die and a coating die, and forming an extruded body core by an extrusion molding method;
Supplying a thermosetting coating composition having a viscosity of 500 to 50,000 mPa · s at 25 ° C. to the coating die;
A molded article having a coating layer on the outer periphery of an extruded molded article core, characterized by having a step of curing the thermosetting coating composition supplied to the outer circumference of the extruded molded article core by heat. A manufacturing method is provided.

  According to the present invention, since the surface coating is continuously performed simultaneously with the extrusion of the metal, it is possible to easily form a coating film having excellent adhesion even with an active metal that is easily oxidized. .

  Further, since the cured coating film transfers the surface of the coating die, it is excellent in smoothness and improves the surface roughness of the extruded product.

  In addition, when post-extruding the extrusion molded body, after performing chemical conversion treatment and treating the surface with an oxide film or the like in an inert and stable state, filling the putty to correct the unevenness of the molded body, after the putty is cured In addition, a complicated coating process is required to perform surface sanding, primer coating, and top coating, but in the present invention, since a coating film is formed on the surface simultaneously with extrusion molding, it may be used as a final product as it is, If necessary, it is only necessary to apply a top coat, and the process can be greatly shortened.

It is side surface sectional drawing explaining the concept of the extrusion apparatus in this invention. It is side surface sectional drawing explaining the concept of the extrusion apparatus which forms the hollow part of the hollow material in this invention.

  Hereafter, the manufacturing method of the molded object of this invention is demonstrated concretely.

  The molded body according to the present invention comprises an extruded molded body core made of metal and a coating film of a thermosetting coating composition formed on the surface thereof.

There are various theories about the mechanism of bonding (joining) an object and an object such as an extruded body core and resin according to the present invention.
1) As a physical bonding force, for example, a throwing effect can be cited as a representative one.
2) The chemical bonding force includes (a) a primary bond such as a covalent bond, (b) a hydrogen bond, and (c) a van der Waals force (secondary bond).

  In order for chemical bonds to appear, things must be sufficiently wet. In addition, in order to form a covalent bond or a hydrogen bond, it must have a functional group for reacting with each other. In the coating by extrusion molding of a thermoplastic resin as in the above-mentioned patent document, it is difficult to express chemical bonds because wettability with the core of the extruded molded body is insufficient. Therefore, in order to give a throwing effect, it seems that the coupling claws and grooves were formed to express the physical bonding force. When the thermosetting paint composition according to the present invention is used, the composition has a functional group such as a hydroxyl group or a carboxyl group, and the core of the extruded molded body until the thermosetting paint starts to cure. The present inventors have envisioned that a strong chemical bonding force is expressed by sufficient wetting.

  As the extruded molded body core made of the metal, conventionally known metals can be used, for example, aluminum, aluminum alloy, magnesium, magnesium alloy, nickel alloy, copper alloy, etc., preferably aluminum, aluminum alloy , Magnesium, and magnesium alloys.

  As at least a part of the resin constituting the thermosetting coating composition, it has a crosslinking system having an unsaturated double bond, a crosslinking system composed of an isocyanate resin and a polyol resin, and a resin having a glycidyl group and a polybasic acid. It is preferable to use a resin comprising at least one crosslinking system selected from the group consisting of a crosslinking system consisting of a combination. For example, as a crosslinking system having an unsaturated double bond, a resin having an unsaturated double bond such as an unsaturated polyester resin, an epoxy acrylate resin, a urethane acrylate resin, or a silicon acrylate resin, and a monomer such as styrene or tripropylene glycol diacrylate And crosslinking by radical reaction with organic peroxides, and as a crosslinking system comprising an isocyanate resin and a polyol resin, urethane crosslinking with an isocyanate resin having an isocyanate group and a resin having a hydroxyl group such as an acrylic polyol resin and a polyester polyol resin. And crosslinking with a polybasic acid and a resin having a glycidyl group such as an epoxy resin.

  Various additives such as pigments such as coloring pigments, extender pigments or rust preventive pigments, antioxidants, polymerization inhibitors, dispersants, mold release agents and the like can be added to these resins as paint components.

  Examples of the color pigment include inorganic pigments such as titanium dioxide, carbon black, dial, and iron yellow, and organic pigments such as phthalocyanine blue and phthalocyanine green.

  Examples of extender pigments include calcium carbonate, talc, clay, silica, mica, barium sulfate, and aluminum hydroxide.

  Examples of the rust preventive pigment include zinc phosphate, rust preventive pigments such as aluminum tripolyphosphate, calcium tripolyphosphate, and magnesium neutralized salt of condensed calcium phosphate, and zinc powder.

  In addition, the addition of a release agent is effective in order to ensure releasability from the coating die. As the mold release agent, a mold release agent usually used for plastic molding such as metal stearate and phosphate can be used.

  As a method for producing a paint, an apparatus for producing an ordinary solvent-type paint can be used. For example, a disperser using glass beads as a dispersion medium, a roll mill, a high-speed disper, and the like can be given.

  The thermosetting coating composition according to the present invention needs to have a viscosity at 25 ° C. in the range of 500 to 50,000 mPa · s. If it is less than 500 mPa · s, it is difficult to obtain a smooth coating film by entraining bubbles in the paint. When it exceeds 50,000 mPa · s, the fluidity of the paint is inferior, and a burrow is formed in the paint film, and a smooth paint film cannot be obtained. Preferably, it is in the range of 1,000 to 40,000 mPa · s, particularly preferably in the range of 2,000 to 35,000 mPa · s.

  A known molding method can be used as the molding method of the core of the extruded molded body. For example, Patent Document 6 and Patent Document 7 can be cited. As an extrusion method, a warm extrusion method or a hot extrusion method is preferable. The processing temperature at the time of extrusion molding is set to 150 to 200 ° C. in the case of warm extrusion molding, and is set to 200 to 550 ° C. in the case of hot extrusion molding. Warm extrusion is a technique performed at a temperature higher than normal temperature but lower than the recrystallization temperature of the material. On the other hand, hot extrusion is a type of hot working, which is a technique that keeps the temperature higher than the temperature at which the material recrystallizes to prevent work hardening and makes the material easy to pass through the mold.

  FIG. 1 is an explanatory view of an embodiment of the production method of the present invention. The heated extrusion molding member 3 and the dummy block 4 are inserted into the container 1, and the extrusion molding member 3 is pressurized by the stem 2 to have a predetermined shape from the hole of the extrusion molding die 5 attached to the front. The extruded product core 6 is extruded. When the molded body passes through the coating die 7 attached to the front for continuous surface coating simultaneously with the extrusion molding, the thermosetting paint sucked up from the coating tank 11 is applied by the pressure pump 10 to the coating die 7. Supply in. In this case, the surface temperature of the coating die 7 is preferably controlled to an arbitrary temperature of 60 to 200 ° C. by a heat medium circulating in the coating die heating pipe 8. If it is less than 60 ° C., it takes too much time to cure the thermosetting paint, and the productivity is poor. If it exceeds 200 ° C., the thermosetting paint is hardened too quickly and fluidity is lowered, and it is difficult to obtain a uniform coating film. Further, the thermosetting paint is cooled by the refrigerant circulating in the coating die cooling pipe 9 so that the thermosetting paint is not cured in this portion. The temperature of the refrigerant is appropriately set according to the curability of the thermosetting paint. Further, the thermosetting paint is supplied at a pressure of 10 to 30 MPa by a pressure feed pump. The pressure can be arbitrarily set within this range. The thermosetting paint is cured by the heat of the coating die and the extruded product core 6.

  Although the thickness of a coating film is not specifically limited in this invention, For example, it is preferable to set it as 0.05-5.0 mm. If it is less than 0.05 mm, it is difficult to conceal the surface irregularities of the extruded product. On the other hand, when the thickness exceeds 5.0 mm, the thickness of the extruded molded body itself becomes too thick, resulting in an increase in weight and a disadvantage in cost. More preferably, it is 0.1-4.0 mm, Most preferably, it is the range of 0.2-3.0 mm.

  In addition, by providing a slight taper so that the inner diameter gradually decreases as the coating die goes to the tip, it is possible to apply pressure to the paint, to compensate for the pressure drop due to shrinkage due to the hardening of the paint, and to smooth the surface And a coated molded article having excellent adhesion to the extruded core material.

  FIG. 2 is an explanatory view of an embodiment of a manufacturing method for forming a hollow portion of the hollow material of the present invention. In this figure, the painting dies for painting are the same as in FIG. 1 and are omitted. A heated extrusion member 3 and a dummy block 4 are inserted into the container 1, the extrusion member 3 is pressurized by the stem 2, and an extrusion die (female mold) for extruding a hollow material attached to the front is provided. ) A hollow extruded core material 20 having a predetermined shape is extruded from a die outlet 15 composed of a combination die formed by 14 and a male mandrel 13. A cooling medium discharge port 18 is provided at the front end surface of the male mandrel 13, and is connected to a cooling medium supply source 19 through the cooling medium flow path 17, so that the cooling medium is cooled on the front end surface of the male mandrel 13. The hollow extruded core member 20 is cooled from the inside of the hollow portion by being discharged into the hollow portion from the discharge port. An example of the cooling medium is air.

  Hereinafter, the present invention will be described in more detail with reference to examples. “Part” means part by mass.

(Examples 1-7 and Comparative Examples 1-2)
Using a generally known extrusion equipment for forming a hollow molded body having a diameter of 100 mm, the magnesium alloy heated to 170 ° C. was warm-extruded to obtain a hollow pipe-shaped molded body. In order to perform surface coating simultaneously with extrusion molding, the extrusion molding was inserted into a coating die whose internal surface temperature was adjusted to 160 ° C., and the thermosetting coating composition shown in Table 1 was applied to the coating die. The resulting product was heated by an extrusion molded body and a coating die, and a molded body surface-coated with a cured coating film was obtained. Note that the inner diameter of the coating die gradually decreases toward the tip. The average thickness of the obtained coating film was 0.5 mm.

  Table 1 shows the results of evaluating the appearance, adhesion and weight drop resistance of the resulting molded product. The appearance and adhesion of the coating film were evaluated according to the following evaluation methods.

<Appearance of coating film>
Visually evaluate the gloss, wrinkles, and uniformity of the coating.
○: No gloss unevenness, no wrinkles, and uniform appearance. Δ ... Slightly uneven gloss, wrinkles are observed. X: Significant gloss unevenness, wrinkles, and uneven appearance.

<Adhesiveness>
According to JIS K 5600-5-6: Adhesion (cross-cut method), an initial coating adhesion test was performed. The adhesion of the coating film was evaluated on the basis of the following 0 to 5 based on the classification of the test results described in JIS K 5600-5-6.
<Stage evaluation>
0: The edges of the cut are completely smooth, and there is no peeling in any lattice eye.
1 ... Small peeling of the coating film at the intersection of cuts. It is clearly not more than 5% that the crosscut is affected.
2 ... The coating is peeled along the edge of the cut and / or at the intersection. The cross-cut part is clearly affected by more than 5% but not more than 15%.
3 ... The coating film is partially or completely peeled along the edge of the cut, and / or various parts of the eye are partially or completely peeled off. The cross-cut portion is clearly affected by more than 15% but not more than 35%.
4 ... The coating film is partially or completely peeled along the edge of the cut, and / or some eyes are partially or completely peeled off. The cross-cut portion is clearly affected by more than 35% but not more than 65%.
5: When the degree of peeling exceeds Category 4.

<Weight drop resistance>
According to JIS K 5600-5-3: weight drop resistance (DuPont type), an initial weight drop resistance test was performed under the following test conditions.
a) Atmospheric temperature: 0 ° C
b) Attach a shooting die having a radius of 6.35 ± 0.3 mm and a cradle, and sandwich the test piece with the coating surface facing upward.
c) A weight of 500 ± 1 g is dropped onto a shooting mold from a height of 20 cm.
d) After leaving in a room at 23 ° C. for 1 hour, visually check for damage to the paint surface.
(Judgment)
For two test pieces, “pass” when no cracking / peeling of the coating film due to impact deformation of the test piece is observed, and “cracking / peeling” when cracking / peeling is recognized due to deformation due to impact.

(* 1) 55 parts of epoxy acrylate having a number average molecular weight of 700, 45 parts of styrene monomer (* 2) 70 parts of non-yellowing urethane acrylate having a number average molecular weight of 2000, 30 parts of styrene monomer (* 3) isophthalic acid having a number average molecular weight of 2500 -Based unsaturated polyester resin 70 parts, styrene monomer 30 parts (* 4) tripropylene glycol diacrylate (* 5) number average molecular weight 8000 polymethyl methacrylate 30 parts, styrene monomer 70 parts (* 6) t-butylperoxy Benzoate

(Example 8)
The same procedure as in Example 1 was performed except that the thermosetting coating composition shown in Table 2 was used. The evaluation results are shown in Table 2.

(* 7) Desmophen VPLS2249-1 polyester polyol, manufactured by Bayer Material Science AG (* 8) Desmodur XP2410 aliphatic polyisocyanate, manufactured by Bayer Material Science AG

(Examples 9 to 10)
The same method as in Example 1 was used except that the thermosetting coating composition shown in Table 3 was used. The evaluation results are shown in Table 3.

(* 9) Epoxy equivalent 190, number average molecular weight 380
(* 10) Aromatic polyamine, manufactured by Yuka Shell Epoxy

(Examples 11 to 12)
The aluminum alloy heated to 550 ° C. was hot-extruded by using an extrusion equipment for forming a φ100 mm hollow molded body capable of discharging cooling air from the inside of the hollow molded body. A molded body was obtained. At the same time as the molded member was extruded, cooling air was discharged into the hollow molded body. In order to continuously perform surface coating simultaneously with extrusion molding, the extrusion molding was inserted into a coating die whose internal surface temperature was adjusted to 200 ° C., and the thermosetting coating composition shown in Table 4 was applied to the coating die. The resulting product was heated by an extrusion molded body and a coating die, and a molded body surface-coated with a cured coating film was obtained. Note that the inner diameter of the coating die gradually decreases toward the tip. The average thickness of the obtained coating film was 0.3 mm. The evaluation results are shown in Table 4.

DESCRIPTION OF SYMBOLS 1 Container 2 Stem 3 Extrusion molding member 4 Dummy block 5 Extrusion die 6 Extrusion core 7 Coating die 8 Coating die heating pipe 9 Coating die cooling pipe 10 Paint pumping pump 11 Paint tank 12 Coating Membrane 13 Male Mandrel 14 Extrusion Die (Female)
15 Die outlet 16 Die ring 17 Cooling medium flow path 18 Cooling medium discharge port 19 Cooling medium supply source 20 Hollow extruded core material

Claims (9)

Supplying an extrusion molding member to an extrusion molding machine equipped with an extrusion molding die and a coating die, and forming an extruded molded body core by an extrusion molding method;
Supplying a thermosetting coating composition having a viscosity of 500 to 50,000 mPa · s at 25 ° C. to the coating die;
A molded article having a coating layer on the outer periphery of an extruded molded article core, characterized by having a step of curing the thermosetting coating composition supplied to the outer circumference of the extruded molded article core by heat. Production method.   The method for producing a molded body according to claim 1, wherein the extrusion molding member is magnesium or a magnesium alloy.   The method for producing a molded body according to claim 1, wherein the extrusion molding member is aluminum or an aluminum alloy.   The method for producing a molded body according to any one of claims 1 to 3, wherein the extrusion molding method is warm extrusion molding, and a processing temperature during the extrusion processing is 150 to 200 ° C.   The said extrusion molding method is hot extrusion molding, and the processing temperature at the time of the extrusion process is 200-550 degreeC, The manufacturing method of the molded object in any one of Claims 1-3.   In an extrusion facility for hollow material extrusion, a discharge port for discharging a cooling medium is provided at the tip surface of a male mandrel that forms a hollow portion of the hollow material, and the cooling medium is extruded through the discharge port during extrusion. The method for producing a molded body according to any one of claims 1 to 5, wherein the molded body is discharged into a hollow portion of the body.   The method for producing a molded body according to any one of claims 1 to 6, wherein an internal surface temperature of the coating die is 60 to 200 ° C.   The manufacturing method of the molded object according to any one of claims 1 to 7, wherein the coating die has an inner diameter that gradually decreases toward the tip.   From a cross-linking system having an unsaturated double bond as at least a part of the resin constituting the thermosetting coating composition, a cross-linking system comprising an isocyanate resin and a polyol resin, and a combination comprising a resin having a glycidyl group and a polybasic acid The manufacturing method of the molded object in any one of Claims 1-8 using the resin which comprises at least 1 crosslinking system chosen from the group which consists of a crosslinking system which becomes.