JP7560962B2 - Composite molded products and grooved plastic molded products - Google Patents

Description

The present invention relates to a composite molded product and a grooved resin molded product for forming the composite molded product.

In recent years, in fields such as automobiles, electrical appliances, and industrial equipment, there has been a growing trend to replace some metal molded products with resin molded products in order to meet the demands of reducing carbon dioxide emissions and manufacturing costs. As a result, composite molded products that integrate resin molded products with metal molded products have become widespread. In addition, composite molded products that integrate molded products made of the same or different materials have also become widespread.

For example, Patent Document 1 proposes a method for manufacturing a composite molded product in which one molded product is integrated with another molded product, in which a nanostructure is formed on the surface of one resin molded product by irradiating the surface with electromagnetic radiation, and then the other resin molded product is brought into contact with the surface, filled, molded, and integrated.

Patent document 2 proposes a technology in which a groove is formed by a laser on the joining surface of a first resin molded product containing glass fibers, and a second resin is injection molded onto the joining surface to produce a composite molded product.

Special Publication No. 2011-529404 JP 2015-91642 A

However, there is room for further improvement in the strength when one molded product is joined to another, particularly when the resin molded product does not contain inorganic fillers such as glass fiber.

The present invention was made to solve the above problems, and its purpose is to provide a composite molded product that can further increase the strength when joined to other molded products, even if the resin molded product does not contain a fibrous inorganic filler such as glass fiber.

The object of the present invention has been achieved by the following.
1) A composite molded product which is an integrated product of a first molded product made of resin A having a groove formed on the surface of a joint by laser irradiation and resin B, wherein the resin A does not contain fibrous inorganic compounds, the thermal decomposition temperature of the resin A in air determined by TGA is 300°C or higher, and the difference between the thermal decomposition temperature of the resin A and the higher of its melting point or glass transition temperature is 130°C or higher, and the angle θ of the groove in the depth direction when the perpendicular direction of the joint is 0° is 0<θ<90°.
2) The composite molded product according to 1) above, wherein the angle θ in the depth direction is 10<θ<80°.
3) The composite molded product according to 1) or 2) above, wherein the depth of the groove is at least 1/2 of the length of the groove in the short direction.
4) A grooved resin molded product made of resin A in which grooves are formed on the surface of a joint by laser irradiation, wherein the angle θ of the depth direction of the groove is 0<θ<90° when the perpendicular direction to the joint is taken as 0°.

The composite molded product of the present invention acts as an anchor by providing a stronger bond due to the groove angle θ, preventing damage to the molded product, resulting in a significant increase in the strength of the composite molded product.

FIG. 2 is a schematic diagram of a first molded product showing the groove angle θ of the present invention. 1 is an example of an embodiment of a composite molded product of the present invention. 1 is another example of an embodiment of the composite molded article of the present invention. 2 is a schematic diagram showing striped grooves formed at the joint of the first molded product of the present invention. FIG. FIG. 2 is a schematic cross-sectional view showing the striped grooves of the present invention. 2 is a schematic diagram showing a lattice-shaped groove formed in a joint of the first molded product of the present invention. FIG. FIG. 2 is a schematic diagram showing a tensile test of the composite molded product of the present invention. FIG. 1 is a schematic cross-sectional view of a conventional composite molded product.

The following describes in detail the embodiments of the present invention, but the present invention is not limited to the following embodiments and can be modified as appropriate within the scope of the object of the present invention. Note that where explanations overlap, they may be omitted as appropriate, but this does not limit the gist of the invention.

<Composite molded products>
The composite molded product of the present invention is a composite molded product which is integrated by molding a first molded product made of resin A having a groove formed on the surface of the joint by laser irradiation with resin B, and is characterized in that the angle θ of the depth direction of the groove when the vertical direction of the joint is 0° is 0<θ<90°.

<First molded product>
<Groove>
A plurality of grooves are formed on the surface of the first molded product. In the present invention, the first molded product, which is a grooved resin molded product, is integrated with another molded product at the surface having the grooves as a joint to produce a composite molded product.

The anchor effect is enhanced by providing multiple grooves on the surface of the first molded product. Multiple grooves may be formed by folding back adjacent grooves into a single groove, or multiple grooves may be formed.

The grooves may be arranged in a line like contour lines with both ends connected, or may be formed in stripes that do not intersect, or in a grid pattern where the grooves intersect, or in polka dots. If the grooves are formed in a grid pattern, they may be diamond shaped.

The length of the groove is not particularly limited, and if the groove is short, the shape of the opening may be rectangular, round, or elliptical. To obtain an anchor effect, it is preferable that the groove is long.

The distance between adjacent grooves in the present invention is preferably 0.5 to 8 times the width of the groove, i.e., if the groove width is 200 μm, then 150 μm to 1600 μm, and more preferably 1 to 4 times the width of the groove, i.e., if the groove width is 200 μm, then 200 μm to 800 μm.

The distance between adjacent grooves is preferably 1000 μm or less if the grooves are in a diagonal grid shape, and more preferably 1000 μm or less if they are linear in one direction. The depth of the grooves is at least 1/2 the short-side length of the groove, preferably at least 1 time, and more preferably at least 3 times.

<Groove depth angle θ>
Fig. 1 is a schematic diagram of the first molded product of the present invention. The upper part is the joint, the arrow direction is the vertical direction to the joint, and θ is the angle in the depth direction of the groove. θ is 0<θ<90°, preferably 10≦θ≦80°, more preferably 15≦θ≦70°, and particularly preferably 20≦θ≦60°.

By adding an angle θ to the depth direction of the groove, the bonding strength of the first molded part in the composite molded product can be greatly improved compared to when θ = 0°. In particular, the angle θ acts as resistance against vertical tensile forces, resulting in a significant effect.

<Resin A of first molded product>
Resin A of the first molded product is capable of forming grooves by laser irradiation, and may be a thermoplastic resin or a thermosetting resin. The thermal decomposition temperature of resin A can be measured by TGA in air and is 300° C. or higher, preferably 400° C. or higher, and more preferably 450° C. or higher.

The difference between the thermal decomposition temperature of resin A and the higher of its melting point or glass transition temperature is preferably 130°C or more, more preferably 150°C or more, and most preferably 200°C or more. If it is less than 130°C, when resin A is gasified by laser irradiation to form grooves, the surrounding area melts, making it difficult to process fine shapes.

Examples of resins suitable for the first molded product include polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), polystyrene (PS), polyamide (PA), etc.

Resin A may contain other components as long as they do not impair the effects of the present invention. Examples of other components include additives such as nucleating agents, pigments, antioxidants, stabilizers, plasticizers, lubricants, release agents, and flame retardants.

<Method of forming grooves by laser irradiation>
The first molded article of the present invention is irradiated with a laser to partially remove the resin, thereby forming a plurality of grooves.

The laser irradiation is set based on the type of material to be irradiated and the output of the laser device, but unless the appropriate amount of energy is irradiated into the resin to form the groove, it may be difficult to form a groove of the specified width and depth, so it is preferable to perform the irradiation in multiple stages.

In addition, to form fine grooves, a pulsed wave laser is more effective than a continuous wave laser. Continuous waves tend to melt the surrounding area, making it difficult to control the laser output and speed to form fine grooves. The pulse width of the pulsed wave is preferably about 50 ns or less.

The angle θ can be adjusted by irradiating the joint with a laser at the same angle as θ. A laser absorbent such as a pigment or dye can also be added to resin A to improve absorption of the laser irradiation. Carbon black is a preferred laser absorbent.

If the presence of a carbonized layer of resin can be confirmed by Raman spectroscopic analysis of the groove, it can be determined that the groove was formed by irradiation with laser light.

<Composite molded products>
Figures 2 and 3 are schematic diagrams of enlarged cross sections of the composite molded product of the present invention. In Figure 2, grooves are formed in parallel in the same direction, and the θ of each groove is the same. Figure 3 shows a composite molded product with grooves having θ in opposite directions. In addition to 0<θ<90°, θ=0° may also be included. In that case, it is preferable that 60% or more of the groove area is 0<θ<90°.

<Resin B>
There is no particular restriction on the type of thermoplastic or thermosetting resin as long as it is an injection moldable resin for the resin B. Examples of the resin B include polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyacetal (POM), polypropylene (PP), polyethylene (PE), polystyrene (PS), polycarbonate (PC), and polyamide (PA).

<Method of forming composite molded product>
The composite molded product of the present invention can be obtained not only by multiple molding, but also by heating a resin molded product, such as ultrasonic welding, hot plate welding, laser welding, high-frequency induction heating welding, heat press molding, etc. In addition, it can also be obtained by painting, printing, room temperature curing, heat curing, moisture curing, two-component curing, UV curing, hot melt curing, etc. of adhesives.

In the case of double molding, the first molded product is placed in a mold, and thermoplastic resin B is sealed inside the mold, with the surface with the groove as the contact surface. Resin B also enters the grooves, and by cooling in this state, a composite molded product can be formed.

In this way, double molding makes it easy to fill the inside of the grooves due to the pressure generated when resin B is sealed inside the mold.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, measurements were carried out in an atmosphere of 23° C. and 50% RH.
Example 1

The materials used in the examples are as follows:
<Resin A>
A-1 PPS: Polyplastics Co., Ltd. DURAFIDE (registered trademark) 0220A9 HD9100
A-2 LCP: Polyplastics Co., Ltd. LAPEROS (registered trademark) A9500VD3003
A-3 POM: Polyplastics Co., Ltd. Duracon (registered trademark) M90-44 CD3068

<Resin B>
B-1 POM: Polyplastics Co., Ltd., Duracon (registered trademark) M450-44 CF2001

<Preparation of first molded product>
<Preparation of test specimens>
The first molded product was prepared in the shape of an Izod test piece according to ASTM D256 (W12.7×D6.4×L63.5 mm, notch notched).
Resin A was injection molded into an ASTM Izod test specimen mold under the following molding conditions:
PPS: Cylinder temperature 310°C, mold temperature 140°C
LCP: Cylinder temperature 310°C, mold temperature 80°C
POM: Cylinder temperature 190℃, mold temperature 80℃

Then, a laser irradiation device was used to perform surface treatment on the joints from a specified angle using a laser with an irradiation diameter of 80 μm, producing a first molded product. The stripes were irradiated to create grooves with a pitch of 1.0 mm, a width of 80 μm, and a depth of approximately 1000 μm, as shown in Figures 4 and 5. The lattice pattern was irradiated to create grooves with a pitch of 2.0 mm in the same direction, a width of 80 μm, and a depth of 300 μm, as shown in Figures 6 and 5.

In the table, "reverse" refers to the second irradiation angle, which is a V-shape, and indicates that the irradiation was performed from the opposite side, 180°, from the first irradiation position.

<Laser irradiation conditions>
Laser wavelength: 1064 nm
Laser irradiation diameter: 80 μm
Irradiation device: Keyence laser marker MD-X1520
Laser output: 22.5W
Irradiation speed: 20mm/s
Pulse width: 4.6ns

<Production of composite molded products>
The test piece prepared above was double molded from resin B using an ASTM bending test piece mold under conditions of a cylinder temperature of 190°C and a mold temperature of 80°C to prepare an ASTM bending test piece (12.7 x 6.4 x 127 D790) mm as shown in Figure 7. The cross-sectional area of the joint is 81.3 ^mm2 (12.7 x 6.4 mm).

<Bonding strength measurement>
The tensile breaking strength of the ASTM bending test piece of the prepared composite molded product sample was measured using a universal testing machine, and the tensile stress was calculated from the cross-sectional area of the joint. The results are shown in Tables 1 and 2.
Breaking speed: 10 mm/min
Testing machine: Shimadzu Corporation universal testing machine AG-20kNXDplus

<Weight loss temperature>
10 mg of resin A was weighed out, and the temperature was increased at 10° C./min in an air atmosphere using a TG/DTA6200 manufactured by Seiko Electronics, and the temperature at which the weight loss rate reached 1% was recorded as the weight loss temperature.

<Melting point, glass transition temperature>
5 mg of resin A was weighed out, and the melting point was measured under nitrogen at 10° C./min using a DIAMOND DSC manufactured by Perkinelmer Corp. Note that A-2LCP is a liquid crystal polymer and exhibits liquid crystallinity in a molten state, so the glass transition temperature was not measured.

From Tables 1 and 2, it can be seen that the grooves of the present invention having 0<θ<90° have improved joint strength compared to θ=0.

1 First molded product (resin A)
2 Vertical direction of joint 3 Groove 4 Joint 5 Composite molded product 6 Resin B
P Tensile tension

Claims (3)

A first molded product made of resin A having a groove formed on the surface of the joint by laser irradiation, and a composite molded product integrated with resin B by molding,
The resin A does not contain a fibrous inorganic compound,
The thermal decomposition temperature of the resin A in air by TGA is 300° C. or higher, and the difference between the thermal decomposition temperature of the resin A and the higher of the melting point or the glass transition temperature is 130° C. or higher;
an angle θ of the groove in the depth direction when the perpendicular direction of the joint is 0° is 0<θ<90°;
The grooves are formed in a striped or lattice pattern in the composite molded product. The composite molded product according to claim 1, wherein the depth angle θ is 10≦θ≦80°. A grooved resin molded product made of resin A in which grooves are formed on the surface of a joint by laser irradiation,
The resin A does not contain a fibrous inorganic compound,
The thermal decomposition temperature of the resin A in air by TGA is 300° C. or higher, and the difference between the thermal decomposition temperature of the resin A and the higher of the melting point or the glass transition temperature is 130° C. or higher;
The angle θ of the groove in the depth direction is 0<θ<90°, where the perpendicular direction of the joint is 0°.
The grooved resin molded product has grooves formed in a stripe or lattice pattern.

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