JPH07266373A - Thermoplastic elastomer molded product - Google Patents

Abstract

PURPOSE:To obtain a thermoplastic elastomer molded product having surface hardness (scratch resistance) and weathering resistance by the usual injection molding of a thermoplastic elastomer being a rubbery soft resin used as a molding material. CONSTITUTION:In producing a thermoplastic elastomer molded product using an injection molding machine, a thermoplastic synthetic resin sheet or film is arranged so as to come into contact with the inner surface of at least one mold and a molten thermoplastic polyurethane elastomer is injected in the mold as a molding material to be integrally laminated to the sheet or film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic elastomer synthetic resin molded product, particularly a soft resin molded product having excellent surface hardness, and a molding method thereof.

[0002]

2. Description of the Related Art In recent years, thermoplastic elastomer moldings have been used in the fields of automobile parts, building material parts, precision equipment parts, sundries and the like. However, most thermoplastic elastomers
Since it has poor weather resistance, it cannot be used for outdoor applications, and it has a drawback that it has no surface hardness and is inferior in scratch resistance.

As a method for improving the scratch resistance of molded articles,
There is a method of coating the surface of a molded product with a hard coating agent to improve its surface hardness. Examples of hard coating agents include epoxy resin-based, acrylic resin-based, amino resin-based, and polysiloxane-based hard coating agents. These hard coat agent compositions are dissolved in a suitable solvent and applied to a molded product as a hard coat film having a thickness of several microns to several tens of microns by means such as spray coating or dip coating. Next, this hard coat film is cured by means such as heating or ultraviolet irradiation to become a cured film having surface hardness. As described above, the surface hardness is usually given to the synthetic resin molded product by the secondary processing method.

The production by these secondary processing methods can improve the surface hardness of the target molded article, but from the viewpoint of industrial production, there are the following problems and it is not always preferable. (1) Molded products formed by injection molding have molecular orientation and residual stress, and when the molded products are coated, cracks and crazing occur in the molded products due to the influence of the paint solvent, resulting in product defects. . (2) When the coating is cured by heat treatment, there is a problem that the molded product is deformed due to the molecular orientation and residual stress of the molded product. (3) Since the plastic material has a high electrostatic property, it is not possible to completely avoid contamination due to electrostatic adhesion of dust, dust, etc. in the painting process, and the hard coat agent coating on the molded product is incomplete, resulting in poor appearance. cause. For this reason, a molded product washing step for removing dust, dust, etc. adhering to the surface of the molded product is required, resulting in a marked deterioration in productivity.

(4) When spray coating or dip coating is applied to a molded product having a complicated shape, dripping of the coating liquid or accumulation of the coating liquid is liable to occur and appearance defects are likely to occur, which limits the shape of the molded product. is there. (5) When dip-coating only one side of the molded product, the non-painted part must be masked before painting so that the paint does not adhere to the non-painted part. Further, when the non-painted portion has a complicated shape, there is a problem that the masking process becomes difficult. The above problems have been fatal obstacles in the coating process of synthetic resin products. Furthermore,
It was difficult to perform a surface hardening treatment on a soft thermoplastic elastomer molded article which is a rubber-like elastic body. This is because, when a cured film is formed on the surface of the rubber-like elastic body, the cured film is cracked when the molded product is slightly deformed during actual use.

[0006]

SUMMARY OF THE INVENTION In the present invention, when surface hardness (scratch resistance) and weather resistance are required, a thermoplastic elastomer which is a rubber-like soft resin is used as a molding agent, and ordinary molding is performed. It is an object to provide a thermoplastic elastomer molded article having surface hardness (scratch resistance) and weather resistance only in the steps and a molding method thereof.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies on a molding method of a soft thermoplastic elastomer molded article which requires surface hardness (scratch resistance) and weather resistance, and as a result, The inventors have found that the above problems can be solved by injecting a molding material after disposing a thermoplastic rigid resin sheet, and further a synthetic resin sheet with a hard coat layer, and completed the present invention. That is, the present invention is a thermoplastic elastomer molded article molded using an injection molding machine, wherein a thermoplastic synthetic resin sheet or film is disposed so as to contact at least one surface in a mold,
Then, a laminated thermoplastic elastomer molded product obtained by injecting a molten thermoplastic polyurethane elastomer into a mold as a molding material, and a method for molding a thermoplastic elastomer molded by using an injection molding machine. Then, a thermoplastic synthetic resin sheet or film is disposed so as to contact at least one surface in the mold, and then a thermoplastic polyurethane elastomer is injected as a molding material into the mold to obtain an excellent surface hardness. The present invention relates to a method for molding a thermoplastic elastomer. The present invention will be described below.

As the thermoplastic synthetic resin sheet or film (hereinafter sometimes simply referred to as a sheet) used in the present invention, a polycarbonate resin, a polycarbonate resin-polybutylene terephthalate resin composition, polymethylmethacrylate (PMMA), acrylonitrile-styrene is used. Although a thermoplastic resin sheet such as a copolymer (AS resin) or polystyrene can be used, an aromatic polycarbonate having excellent impact resistance (hereinafter, sometimes referred to as PC)
Is preferred. As the PC, one or more divalent phenol compounds exemplified by 2,2-bis (4-hydroxyphenyl) -propane and 2,2-bis (3,5-dibromo-4-hydroxyphenyl) -propane. And a carbonate precursor exemplified by phosgene by a known method. When a sheet having a thickness of 0.1 mm to 2.0 mm is selected, the product surface appearance and formability are improved. 0.1 mm
When a sheet of less than 2 is used, wrinkles may occur on the surface of the sheet in the final filling portion, and when it exceeds 2.0 mm, it may be difficult to process the sheet into an appropriate shape.

The thermoplastic elastomer used in the present invention is a thermoplastic polyurethane elastomer having rubber-like flexibility even at room temperature and can be classified into polyester type and polyether type. The polyester type is classified into adipate type (ethylene adipate type, butylene adipate type, hexane adipate type), caprolactone type, and polycarbonate type, and these thermoplastic polyurethane elastomers can be used in the present invention.

As a method for producing the thermoplastic polyurethane elastomer, a polyisocyanate, a polyol and a chain extender are used, and the thermoplastic polyurethane elastomer is synthesized by a commonly used one-shot method or a prepolymer method. As the polyisocyanate used, those obtained from aromatic and alicyclic diisocyanates, specifically 4,4′-diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), isophorone diisocyanate (IPDI), methylenebis- (4- Cyclohexyl)
Examples are diisocyanate (HMDI) and 1,4-diisocyanate benzene (PPDI). Specific examples of the polyols include caplacton-based polyols, adipate-based polyols, polyether-based polyols, and polycarbonate-based polyols. Specifically, polylactone, polycapractone polyol, poly (ethylene adipate) polyol, poly (ethylene succinate).
Polyol, poly (butylene adipate) polyol,
Examples thereof include poly (ethylene sebacate) polyol and poly (diethylene ether adipate) polyol. Further, the thermoplastic polyurethane polyol used in the present invention preferably has a number average molecular weight selected from the range of 1000 to 2000.

The thermoplastic polyurethane elastomer synthesized by the above production method has a Shore A hardness of 60 to 90 obtained based on the method of JIS K7311 A type.
The shear D hardness obtained according to the method of JIS K7311 D type in the range of 50 to 74 can be obtained, and the hardness is appropriately selected depending on the use condition.

In the present invention, the adhesive performance between the thermoplastic polyurethane elastomer, which is a molding material, and the thermoplastic synthetic resin sheet is required. However, by using the thermoplastic polyurethane elastomer described above, a special adhesive layer It is possible to easily bond a thermoplastic polyurethane elastomer to a PC sheet or the like used as a thermoplastic synthetic resin sheet without using, and the composition of the thermoplastic polyurethane elastomer is not particularly limited. Even if the thermoplastic synthetic resin sheet is mixed with additives having infrared absorption ability and ultraviolet absorption ability to improve weather resistance, the adhesive strength between the material and the sheet is 90 kg peel strength of 5 kg / cm or more. Has adhesive strength.

The thermoplastic synthetic resin sheet with a hard coat layer is obtained as follows. The thermoplastic synthetic resin sheet of the present invention is molded to a predetermined thickness by an extrusion molding method or the like.
In this extrusion method, usually, a thermoplastic synthetic resin that is heated and melted is extruded from a die placed at a right angle to an extruder, and while being glossed by a polishing roll, it is cooled and trimmed to be cut into a predetermined size, It is considered a product. In this way, a thermoplastic synthetic resin sheet having the least possible molecular orientation or residual stress is prepared.

Next, the thermoplastic synthetic resin sheet is subjected to surface treatment such as washing with water or cleaning. Then, one surface is precoated with a precoat liquid, if necessary, and then a hard coat agent coating material is applied to a predetermined thickness. Then, this coated hard coating agent is sufficiently cured in an ultraviolet or infrared oven to form a hard coat film, and becomes a thermoplastic synthetic resin sheet having excellent surface hardness and weather resistance. It is desirable that the hard coat-treated surface be disposed in the mold cavity so as to be in contact with the mold surface.

Examples of the hard coating agent include epoxy resin type, acrylic resin type, amino resin type, polysiloxane type and the like.

In the pre-coating treatment which is a pre-process of coating the hard coat agent, for example, a pre-coating liquid containing γ-aminopropylmethoxysilane, alcohol and water or a pre-coating liquid of thermosetting acrylic modified resin solution is used. The hard coat film-forming thermoplastic synthetic resin sheet is punched into an outer surface shaped piece of a desired synthetic resin molded product.
This punching piece is obtained by a known punching device.

As a method for mounting the thermoplastic synthetic resin sheet, a sheet is punched into a mold cavity shape by a press machine, and the gate and tab portions of the sheet are preliminarily punched and fixed to a pin provided on the mold, By attaching an iron piece to the sheet tab part and mounting it by a known method of embedding a magnet in the mold part at the same position and mounting it, or by mounting a sheet shaped in advance in the mold cavity shape by vacuum molding etc. Attach and mold.

One example of the manufacturing method of the present invention will be described in detail with reference to FIG. 1, but the present invention is not limited to the following molding method. The symbols used in FIGS. 1 and 2 are as follows. 1: Mold 2: Moving side mold 3: Fixed side mold 4: Cavity part 5: Cavity surface 6: Punching piece 7: Molten resin 8: Injection molding means 9: Hard coat film forming surface 10: Hard coat film non Forming surface 11: Sprue 12: Fluidized melt layer 13: Solidified skin layer 14: Solidified skin layer 15: Molded product

A moving side mold 2 of a mold 1 as shown in FIG. 1 mounted on an injection molding machine for forming a desired molded product.
Then, the PC punching piece 6 is mounted in the cavity portion 4. The punched piece 6 is arranged on the cavity surface side 5 which is the outer surface of the molded product so that the hard coat film forming surface 9 is located on the outermost surface of the synthetic resin molded product as the final product. The punched piece 6 thus arranged is held on the predetermined cavity surface by a known method, and the moving die 2 is closed. Then, a thermoplastic polyurethane elastomer (hereinafter, referred to as a molten resin) which is a molten resin is introduced into the cavity 4 so that the hard coat film forming surface 9 of the punched piece 6 becomes the outer surface of the final molded product and the hard coat film non-forming surface 10 becomes the inner surface.
(Sometimes referred to as TPU) 7 is high-pressure injected from injection molding means 8 such as an injection molding machine nozzle.

The high-pressure injected TPU 7 is injected into the cavity portion 4 through the sprue 11. The molten resin 7 that has entered the cavity portion 4 is cooled immediately as soon as it directly contacts the cavity surface or indirectly through the punched piece 6 and forms the solidified layer skins 13 and 14.
The fluidized melted layer 12 that has not been cooled flows inside the already formed solidified layers 13 and 14 further forward of the existing solidified layers due to the injection pressure. Similarly, the fluidized molten layer 12 that has flowed forward, that is, the molten TPU, is cooled directly as soon as it directly contacts the cavity surface or indirectly through the punched piece 6 and forms a solidified layer.

Molten resin 7 injected into the cavity 4
Is injected while forming the solidified skin layers 13 and 14 on the cavity surface or the contact surface with the punched piece. As a result, the PC sheet of the punched piece 6 is instantly shaped by the molten resin TPU in the cavity portion 4 along the cavity surface without being displaced from the original mounting position.

On the other hand, in the hard coat film non-forming surface 10 of the punched piece 6 of the PC sheet, the interface 10 is melted by the heat of the TPU 7. Since the molten TPU 7 and the film non-forming surface 10 of the PC sheet punched piece 6 are PC and TPU,
Both are bonded via the interface 10. Therefore, PC
The sheet blank and the molten TPU are completely integrated at the interface 10.

After cooling, the synthetic resin molded product is taken out of the mold 1. Since the molded product is a product in which the desired part is completely covered with the hard coat film, no further post-process is required. The punched pieces of the PC sheet may be arranged in the mold cavity so that the punched pieces are located on both the outermost surface and the innermost surface of the final molded product. In this case, both the outer surface and the inner surface of the final molded product are covered with the hard coat film.
As a molding device for molding a molded product, a known injection molding machine and a metal mold may be prepared, and no special auxiliary equipment is required.

By mixing an additive such as a coloring agent or an ultraviolet absorber in the PC sheet in advance, the synthetic resin molded article can be colored in a desired color without mixing such an additive in the molten resin material. It can have performance and ultraviolet absorption performance. Dyes and pigments used as colorants include titanium white, red iron oxide, and spinel green as inorganic pigments, quinacridone-based, perylene-based, anthraquinone-based, carbon black as organic pigments, and perylene-based and perinone-based dyes. , Anthraquinone system, and heterocyclic system are exemplified.
Further, if a desired character or code is printed in advance on the surface of the PC sheet opposite to the hard coat film surface, the character or code is not located on the outer surface of the molded product and is not permanently erased.

On one surface of the sheet used, weather resistance,
At least one or more of antistatic property and antifogging property can be imparted, and the impartation of these functions is described, for example, in JP-A-60-250927 and JP-A-60-2535.
No. 18, JP-A-60-523516, JP-A No. 60-253518, etc. As described in JP-A No. 60-235518, etc., a PC sheet having a coating excellent in weather resistance, antistatic property and antifogging property on one surface. Can be mounted in a mold and then the molding material is injected into the mold.

[0026]

EXAMPLES The present invention will be specifically described below with reference to examples. In the examples, each physical property value was measured as follows. (1) Taber abrasion test (ASTM D1044-5
6) is wear wheel CS-10F, under a load of 500 g, 100
Cycled. The haze value was measured after the test. (2) In the steel wool abrasion test, # 0000 steel wool was subjected to 15 reciprocating abrasions under a load of 1000 g.
The haze value was measured after the test. (3) Sunshine weather meter test, black panel temperature 63 ℃, with rain (18 minutes out of 120 minutes),
The treatment was carried out for 3000 hours. After the test, the degree of yellowing was measured. (4) The haze value was measured using a direct reading haze computer (manufactured by Suga Test Instruments Co., Ltd.). (5) The degree of yellowing was measured using an SM color computer (manufactured by Suga Test Instruments).

Example 1 A cavity 4 shown in FIG. 1 as a mold has a thickness of 3
A disk mold having a cavity 4 having a diameter of 100 mm and a diameter of 100 mm was used. Sheet thickness 0.5 in the cavity 4 on one side of the mold
mm hard coat hardened film PC sheet (Mitsubishi Gas Chemical Co., Ltd., trade name: Iupilon sheet CFI)
-1) 6 was mounted after being cut into a cavity shape by a press machine. Then, TPU resin material 7 (manufactured by Takeda Birdiche Urethane Industry Co., Ltd., trade name: Elastollan S80A1)
0) was injected and injected under the conditions of a resin temperature of 200 ° C., a mold temperature of 30 ° C., and an injection pressure (gauge pressure: 500 kgf / cm 2) to obtain a disk-shaped molded product 15 shown in FIG.

The molding machine used was a model: 150 MST manufactured by Mitsubishi Heavy Industries, Ltd. The molding material and the sheet were integrated by the heat and pressure of molding to obtain a laminated molded article having a hard coat film layer formed on the surface. Table 1 shows the results of the Taber abrasion test, the steel wool abrasion test, and the sunshine weather test of the hard coat film forming surface of the thus obtained molded product.

Comparative Example 1 Using the same mold as used in Example 1, the same molding material (Takeda Bardish Urethane Industry Co., Ltd., trade name: Elastollan S80A10) was used without mounting a sheet. Molding was carried out under the same molding conditions as in Example 1 to obtain a disk-shaped molded product. Table 1 shows the results of the Taber abrasion test, the steel wool abrasion test, and the sunshine weather test performed on the molded product thus obtained.

Comparative Example 2 Using the same mold as in Example 1, the same molding material (Takeda Bardish Urethane Industry Co., Ltd., trade name: Elastollan S80A10) was used in Example 1 without mounting a sheet. Molding was carried out under the same molding conditions as above to obtain a disk-shaped molded product. Then, masking is applied to one side of the molded product, the silicone-based hard coat liquid is applied by dip coating, and the hard coat film is cured by heat treatment at 120 ° C. for 2 hours. Then, the masking is removed from the molded product and a hard coat cured film is formed on one side. A molded product was given. Table 1 shows the results of carrying out the Taber abrasion test, the steel wool abrasion test and the sunshine weather test on the hard coat film forming surface of the thus obtained molded product.

Table 1 Example, Comparative Example No. Example 1 Comparative Example 1 Comparative Example 2 Taber abrasion test (Δ haze (%)) 2.5 22 17 Steel wool test (Δ haze (%)) 1.5 19 15 Sunshine weather test ( ΔYI (%)) 5.8 22.3 19.7 * In Comparative Example 2, the hard coat film was peeled off during the test in each test.

[0032]

【The invention's effect】

1. Requires surface hardness (scratch resistance) and weather resistance,
Surface hardness (scratch resistance) and weather resistance can be imparted to a thermoplastic elastomer molded article, which is a rubber-like soft resin, only by a normal molding step. 2. Since surface hardness can be imparted at the time of molding, the subsequent steps can be omitted and liquid pool defects can be improved.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a mold section for explaining a molding process of a molded product.

FIG. 2 is a conceptual diagram of a cross section of a molded article obtained in Example 1 of the present invention.

[Explanation of reference numerals] 1: Mold 2: Moving side mold 3: Fixed side mold 4: Cavity part 5: Cavity surface 6: Punching piece 7: Molten resin 8: Injection molding means 9: Hard coat film forming surface 10 : Hard coat film non-formed surface 11: Sprue 12: Fluidized melt layer 13: Solidified skin layer 14: Solidified skin layer 15: Molded product

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hisashi Tahara 5-6-2 Higashi-Hachiman, Hiratsuka-shi, Kanagawa Sanryo Gas Chemical Co., Ltd. Plastics Center

Claims (8)

[Claims] 1. A thermoplastic elastomer molded article molded by using an injection molding machine, wherein a thermoplastic synthetic resin sheet or film is disposed so as to contact at least one surface in a mold, and then, A laminated and integrated thermoplastic elastomer molded product obtained by injecting a molten thermoplastic polyurethane elastomer into a mold as a molding material. 2. The thermoplastic synthetic resin sheet or film is a thermoplastic synthetic resin sheet or film with a hard coat layer, which is obtained by applying a hard coating agent on one surface of a thermoplastic synthetic resin sheet or film and then curing it. Item 2. A thermoplastic elastomer molded article according to item 1. 3. The thermoplastic synthetic resin sheet or film is a transparent aromatic polycarbonate resin.
The thermoplastic elastomer molded article according to. 4. The thermoplastic elastomer molded article according to claim 1, wherein the thermoplastic synthetic resin sheet or film is a thermoplastic synthetic resin sheet or film having ultraviolet absorbing performance, which is formed by adding an ultraviolet absorber in advance. 5. The thermoplastic elastomer molded article according to claim 1, wherein the thermoplastic synthetic resin sheet or film is a thermoplastic synthetic resin sheet or film to which a colorant is added. 6. A method for molding a thermoplastic elastomer molded by using an injection molding machine, which comprises disposing a thermoplastic synthetic resin sheet or film in contact with at least one surface in a mold, and A method for molding a thermoplastic elastomer having excellent surface hardness obtained by injecting a thermoplastic polyurethane elastomer as a molding material into a mold. 7. The method for molding a thermoplastic elastomer according to claim 6, wherein the hard coat agent-coated surface of the synthetic resin sheet or film having a hard coat layer is disposed on at least one mold surface in the mold. 8. A thermoplastic synthetic resin sheet or film is provided on one surface thereof with at least one functional film having weather resistance, antistatic performance, and antifogging performance, and the function imparted to the sheet or film. The method for molding a thermoplastic elastomer according to claim 5, wherein the flexible film is arranged in the mold so as to face the mold surface.