JPH04363221A - Two-layered injection molding - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-layer injection molded product having a hard core and a flexible outer skin, and more particularly to a two-layer injection molded product with excellent adhesion between the core material and the skin material.

0002

2. Description of the Related Art A two-color molding method is known as a method of laminating two resins with different properties into two layers and molding them integrally. For example, the core needs to be hard to maintain its shape.
In addition, when a part needs to have a flexible surface to provide adhesion, in the past, metal or hard resin was used as the core material, and a flexible material such as rubber was molded separately as the skin material. However, attempting to bond these separately molded products together not only increases the number of manufacturing steps, but also causes the two molded products to easily separate, resulting in poor performance depending on the application. It had the drawback of rapidly declining.

[0003] Therefore, so-called two-color molding, in which two types of resin are injected in one molding machine to obtain a two-layer molded product, has been considered.
Various moldings are available. For example, a two-color molded product using polycarbonate as the core material and polyamide elastomer as the skin material is used for clips for securing interior or exterior parts of automobiles to the vehicle body (Japanese Utility Model Publication No. 49713/1983). .

[0004] Furthermore, two-color molded products using polypropylene as the core material and ethylene/propylene rubber as the skin material are known for rollers such as casters of household vacuum cleaners.

[0005]

[Problems to be Solved by the Invention] However, clips using polycarbonate for the core material and polyamide elastomer for the skin material tend to peel off and break during repeated use. Furthermore, since the skin material does not cover the entire clip, and the polycarbonate is exposed except for the abrasion area, there is a problem in chemical resistance, making it difficult to use it on the exterior of an automobile.

On the other hand, in the case of caster rollers, the core material rubs violently against the shaft, so a wear-resistant resin is required, and polypropylene is not satisfactory, and if a resin with excellent wear resistance is selected, The problem is that there is no soft skin material to adhere to. It is an object of the present invention to solve the above-mentioned disadvantages of the prior art and to provide a two-layer injection molded product in which the core material has good wear resistance and the core material and the skin material have excellent adhesion. .

[0007]

[Means for Solving the Problems] In order to solve the above problems, the present invention takes the following measures. That is, the two-layer injection molded product of the present invention is characterized by two-color molding, with a core material made of a resin composition made of polyamide and thermoplastic polyurethane, and a skin material made of a resin composition made of polyetheresteramide and thermoplastic polyurethane. It is something to do.

The configuration of the present invention will be specifically explained below. The polyamide used as the core material in the present invention is preferably a polyamide derived from an aminocarboxylic acid having 6 or more carbon atoms, a lactam, or a salt of a diamine and dicarboxylic acid having 6 or more carbon atoms. Examples of aminocarboxylic acids or lactams having 6 or more carbon atoms or salts of diamines and dicarboxylic acids having 6 or more carbon atoms include ω-aminocaproic acid, ω-aminoenantoic acid, ω-aminocaprylic acid, ω
-aminopelargonic acid, ω-aminocapric acid, 11-
Aminocarboxylic acids such as aminoundecanoic acid and 12-aminododecanoic acid, or lactams such as caprolactam, enantholactam, capryllactam, laurolactam, and hexamethylenediamine-adipate, hexamethylenediamine-sebacate, hexamethylenediamine-isophthal There are salts of diamine-dicarboxylic acids such as acid salts, undecamethylenediamine-avipic acid salts, and 4,4'-diaminodicyclohexylmethane-dodecanedioic acid salts, but 11-aminoundecanoic acid and 12-aminododecanoic acid are particularly preferred. , these can also be used in combination depending on the purpose and use.

It is also permissible to use other amide-forming components as copolymerization components in small amounts for the purpose of lowering the melting point of polyamide or increasing adhesiveness. The thermoplastic polyurethane elastomer used for the core material and skin material of the present invention has a molecular weight of 700 to 8,0.
00 polyethylene glycols, poly(1,2- and 1,3-propylene oxide) glycols, poly(tetramethylene oxide) poly(alkylene oxides) such as glycols or polyethylene adipate, polytetramethylene sebacate, polycaprolactone A prepolymer having an isocyanate group at the end is prepared by reacting an aliphatic polyester glycol with an aromatic diisocyanate such as tolylene diisocyanate or diphenylmethane diisocyanate. Copolymers obtained by chain extension with such diamines are preferably used. A typical example is molecular weight 1
,000 to 3,000 poly(tetramethylene oxide) glycol or polyethylene adipate is reacted with an excess mole of diphenylmethane diisocyanate, and the chain is extended with hydrazine.

The thermoplastic polyurethane elastomer used for the core material and the thermoplastic polyurethane elastomer used for the skin material may be the same or different. on the other hand,
The polyether ester amide used as the skin material of the present invention is at least one polyamide forming component selected from aminocarboxylic acids having 6 or more carbon atoms, lactams, and salts of diamines and dicarboxylic acids having 6 or more carbon atoms ), polyester with a number average molecular weight of 300 to 6,000
Polyetheresteramides derived from (alkylene oxide) glycol (b) and dicarboxylic acid (c) having 4 to 20 carbon atoms are preferred.

The raw material for the polyamide-forming component (a) can be the same as the raw material for the polyamide of the core material, and it is preferable to use the same kind of constituents. Poly(alkylene oxide) glycol (b) in the polyether ester amide of the present invention includes polyethylene glycol, poly(1,2- and 1,3-
Propylene oxide) glycol, poly(tetramethylene oxide) glycol, poly(hexamethylene oxide) glycol, block or random copolymers of ethylene oxide and propylene oxide, block or random copolymers of ethylene oxide and tetrahydrofuran, etc., among others. Poly(tetramethylene oxide) glycol is preferably used because of the excellent physical properties of polyether ester amide, such as heat resistance, water resistance, mechanical strength, and elastic recovery. The number average molecular weight of poly(alkylene oxide) glycol is 30
Although it can be used in the range of 0 to 6,000, a molecular weight range that does not cause coarse phase separation during polymerization and has excellent low temperature properties and mechanical properties is selected, and this optimum molecular weight range is based on the type of poly(alkylene oxide) glycol. It depends. For example, in the case of polyethylene glycol, 300 to 6,000
0, particularly preferably 1,000 to 4,000,
(Propylene oxide) 300-5 for glycol
,000, particularly preferably from 500 to 3,000, and in the case of poly(tetramethylene oxide) glycol, from 500 to 3,000, particularly preferably from 500 to 2,50
Those in the molecular weight range of 0 are preferably used.

The dicarboxylic acid (c) having 4 to 20 carbon atoms in the polyether ester amide of the present invention includes terephthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, diphenyl- Aromatic dicarboxylic acids such as 4,4'-dicarboxylic acid, diphenoxyethane dicarboxylic acid, sodium 3-sulfoisophthalate, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, dicyclohexyl-4,4' - alicyclic dicarboxylic acids such as dicarboxylic acids, and succinic and oxalic acids;
Mention may be made of aliphatic dicarboxylic acids such as adipic acid, sebacic acid, dodecanedic acid (decanedicarboxylic acid). Especially terephthalic acid, ifsotalic acid, 1, 4
- Dicarboxylic acids such as cyclohexane dicarboxylic acid, sebacic acid, and dodecane dicarboxylic acid are preferably used from the viewpoint of polymerizability, color tone, and physical properties of the polymer.

[0013] In order for the effects of the present invention to be most conspicuous, the copolymerization amount of poly(alkylene oxide) glycol (b) in the polyether ester amide is preferably 5 to 90% by weight. When the amount of copolymerization is less than 5% by weight, flexibility and elastic recovery properties are lost, and when it exceeds 90% by weight, high temperature properties and mechanical properties are insufficient. The method for polymerizing polyether ester amide is not particularly limited, and any known method can be used. For example, an aminocarboxylic acid or lactam (a) is reacted with a dicarboxylic acid (c) to create a polyamide prepolymer with carboxylic acid groups at both ends, and then poly(alkylene oxide) glycol (b) is reacted with this under vacuum. Alternatively, the compounds of (a), (b), and (c) above are charged into a reaction tank and heated to react at high temperature in the presence or absence of water to produce a carboxylic acid-terminated polyamide prepolymer, A method is known in which the polymerization is then proceeded under normal pressure or reduced pressure. Also, above (
There is also a method in which the compounds a), (b), and (c) are simultaneously charged into a reaction tank, melt-polymerized, and then polymerized all at once under high vacuum, but this method is preferable because it causes less coloring of the polymer.

[0014] The weight mixing ratio of the core material polyamide and thermoplastic polyurethane in the present invention is preferably 5/95 to 95/5, more preferably 10/90 to 90/10, and even more preferably 20/80 to 95/5. It is 80/20. In addition, the weight mixing ratio of polyether ester amide and thermoplastic polyurethane for the skin material is 10/90 to 90/1.
0 is preferable, more preferably 80/20 to 20/80
, even more preferably from 70/30 to 30/70.

[0015] The resin compositions used as the core material and the skin material in the present invention are preferably melt-kneaded and pelletized in advance, and known methods can be used for melt-kneading. For example, Banbury mixer
Using a rubber roll machine, single-screw or twin-screw extruder, etc.
The resin composition can be made into pellets by melt-kneading, usually at a temperature of 100 to 300°C.

However, industrially, even if resin composition pellets are not made in advance, for example, in the case of a core material, polyamide pellets and polyurethane pellets can be dry blended and fed to a molding machine as is. It can also be melt-kneaded. The resin composition of the present invention also contains known antioxidants, thermal decomposition inhibitors, ultraviolet absorbers, hydrolysis resistance improvers, colorants (pigments, dyes), antistatic agents, conductive agents, flame retardants, and reinforcement. Agents, fillers, lubricants, nucleating agents, mold release agents, plasticizers, adhesion aids, adhesives, etc. can be optionally contained.

The two-layer injection molded product of the present invention includes various clips,
It is especially used for clips for attaching interior and exterior parts to the body of automobiles, and casters for vacuum cleaners, wagons, etc.

[0018]

[Function] The present invention is characterized by extremely good compatibility between the polyether ester amide and the thermoplastic polyurethane elastomer, and the effects of the present invention cannot be obtained with ordinary incompatible polymer blends. Furthermore, surprisingly, the breaking strength of the resin composition of the present invention exceeds the arithmetic mean of the breaking strength values of each component polymer, which also indicates good compatibility.

Furthermore, the role of thermoplastic polyurethane in the present invention is to improve the adhesion between the core material and the skin material by blending it into both the core material and the skin material. Furthermore, since the core material polyamide and the skin material polyether ester amide have the same polyamide structure, they have a relatively high affinity.
In order to further improve adhesion, it is preferable that the polyamide portions of the core material and the skin material have the same polyamide portion.

[0020] In this way, by combining the types of polyamide, thermoplastic polyurethane, and polyether ester amide, it is possible to obtain a molded article according to the purpose and use.

[0021]

[Examples] The present invention will be specifically explained below with reference to Examples. Examples 1 to 6, Comparative Examples 1 to 4 Nylon 12 [“RILSAN” AMNOD (A
TO CHEM)] (N12) and polyether thermoplastic polyurethane ["C74D10" (
Made by Takeda Birdish Urethane Industries) (TPU-1)
were kneaded and pelletized in the proportions shown in Table 1 to obtain core material pellets.

On the other hand, the polyamide component is nylon 12, and the polyether component is poly(tetramethylene glycol).
polyether ester amide [“PEBAX”]
2533 SNOO (manufactured by ATO CHEM)]
(PEEA) and a polyether-based thermoplastic polyurethane [ET270R (manufactured by Takeda Bardis Urethane Industries) (TPU-2) were kneaded and pelletized in the proportions shown in Table 1 to obtain skin material pellets.

[0023] Next, first, 80 mm x 80 mm, thickness 1 m.
Using a mold for M, the mold temperature was 40℃, and the molding temperature was 230℃.
Injection mold the core material at ℃, 80mm x 80mm x 1mm.
A square plate core was obtained. Next, make the mold 80mm x 80mm x
After replacing the mold with a 2mm mold, insert the above square plate core into the mold, and overmold the skin material at a mold temperature of 40°C and a molding temperature of 225°C to form a mold of 80mm x 80m.
A skin/core two-layer injection molded product measuring m×2 mm was obtained.

[0024] This skin/core two-layer injection molded product
Cut into m-wide strips and use a peel tester Autograph 500.
Full scale 50kg, tensile speed 10mm/m
The adhesion strength was measured at in and the results are shown in Table 1.

[0025]

Example 7 Nylon 12 [“RILSAN” AMNOD (
A core material was a pellet prepared by melt-kneading 20 parts by weight of thermoplastic polyurethane ("C74D10" (manufactured by Takeda Bardi Urethane Industries)) and 80 parts by weight of polyether ester amide ("PE").
BAX” 2533 SNOO (ATO CHEM
)] 50 parts by weight and thermoplastic polyurethane ["E
T270R” (manufactured by Takeda Birdy Urethane Industries)
Using a pellet obtained by melt-kneading 50 parts by weight as a skin material, the clip shown in FIGS. 1 and 2 was molded using a two-color molding machine.

The clip 1 shown in FIGS. 1 and 2 has a square plate-shaped locking part 2 at the top, a disc-shaped washer 3 at the middle part, and a deformable anchor-shaped claw 4 at the bottom. These are integrally molded, and the nail 4 is further composed of a core portion 4a as a core layer and a skin portion 4b as a surface layer. This clip 1 is used to attach the waist molding to the car body by fitting the locking part 2 into the groove on the back side of the car waist molding (not shown) and by fitting the claw 4 into the body hole (not shown) in the car body. It's a clip.

[0028] As a result of mounting the clip of this example on a car,
Because the surface of the claw is flexible, it does not damage the paint on the car body when inserted into the hole in the car body, and prevents the occurrence of rust on the body. In addition, as a result of repeatedly attaching and detaching the nail to the hole in the iron plate,
The adhesion between the core part and the skin part was strong and satisfies the practical level. Example 8 The weight ratio of nylon and polyurethane for the core material was 50:50.
The rollers shown in FIGS. 3 and 4 were molded in the same manner as in Example 7, except that dry-blended mixed chips were used.

This roller has a core portion 10a and a skin portion 1.
0b, and is used as a caster for a vacuum cleaner. This roller had good durability as a result of mounting.

[0030]

Effects of the Invention: The two-layer injection molded product of the present invention has excellent adhesion between the core material and the skin material, and the core material has excellent wear resistance, so there is no peeling due to repeated friction, and it is suitable for automobile interiors,
Suitable for clips that lock exterior items, rollers for casters of household goods, etc.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a clip that is an embodiment of the present invention.

FIG. 2 is a sectional view of a clip that is an embodiment of the present invention.

FIG. 3 is a perspective view of a roller that is an embodiment of the present invention.

FIG. 4 is a sectional view of a roller that is an embodiment of the present invention.

[Explanation of symbols]

1 clip
2 Locking part 3 Washer part
4 Claw 4a
core part
4b Skin part 10 Roller
10a Core part 1
0b Skin part

Claims (4)

[Claims] 1. A two-layer injection molded product made of two-color molding: a core material made of a resin composition made of polyamide and thermoplastic polyurethane, and a skin material made of a resin composition made of polyether ester amide and thermoplastic polyurethane. 2. The weight mixing ratio of the core material polyamide and thermoplastic polyurethane is 5-95/95-5, and the weight mixing ratio of the skin material polyetheresteramide and thermoplastic polyurethane is 10-90/90-5. 10. The two-layer injection molded article according to claim 1. 3. The polyamide is a polyamide derived from an aminocarboxylic acid having 6 or more carbon atoms, a lactam, and a salt of a diamine and dicarboxylic acid having 6 or more carbon atoms,
At least one polyamide-forming component in which the polyether ester amide is selected from aminocarboxylic acids having 6 or more carbon atoms, lactams, and salts of diamines and dicarboxylic acids having 6 or more carbon atoms (a), number average molecular weight 300 to 6,
000 poly(alkylene oxide) glycol
(b), and a dicarboxylic acid having 4 to 20 carbon atoms.
2. A two-layer injection molded article according to claim 1, which is a polyetheresteramide derived from (c). 4. The two-layer injection molded product according to claim 1, wherein the number of carbon atoms in the polyamide constituent units of the core material is equal to the number of carbon atoms in the constituent units of the polyamide component of the polyetheresteramide skin material.