JP2008290389A - Injection molding method for manufacturing completely reusable multilayered article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection molding method for making a multilayered molded article having a completely reusable structure. <P>SOLUTION: The injection molding method for manufacturing a completely reusable multilayered article is characterized in that it has a step wherein a multilayered article is composed of (i) a hard layer made of a thermoplastic polymer and (ii) a foamed skin layer made of the thermoplastic polymer having a compatibility with the hard layered material and which injection molds the hard layer to a mold having two surfaces, a step which forms a small clearance of 3-4 mm between the hard layer and the surface of the floated or replaced mold by floating the one surface of the mold or replacing the one surface of the mold, and a step which injects the foamed skin layer into the clearance having been formed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an injection molding process for producing fully reusable multilayers.

  In the automobile industry, the following two types of panels and their processing techniques are used in the interior of a car.

i) Rigid interior panels made of thermoplastic materials such as modified or reinforced PP, PC / ABS, PA / ABS, etc. using injection molding technology. Used),
ii) Soft interior panels usually consisting of three different layers:
Usually, a hard layer (structure) formed by injection molding glass fiber reinforced polypropylene (PP · GF) or mineral reinforced polypropylene, ABS GF, PC / ABS, PPE / HIPS, SMA and / or a mixture thereof,
A foam layer, usually made of polyurethane (PU foam), and a skin layer made of PVC, TPU, etc., manufactured using techniques such as “slush molding” and calendering.

  Under such circumstances, PVC (slash skin) is the most widely used material for the skin layer of dashboards and interior panels. However, PVC is poorly compatible with other thermoplastic polymers, and if there is a PU foam for imparting flexibility, in any case, the product will run out and be separated before being collected and reused.

  For example, as described in Patent Document 1 or Patent Documents 2 and 3, a surface-treated self-structure such as a car dashboard is manufactured by a plurality of processes. A rigid structure is produced by injection molding technology using a plastic polymer.

  Next, the molded product is taken out from the mold, and then subjected to surface treatment and processing with leather or a synthetic cover separately manufactured via a very thin layer of foamed material. For example, this leather, in effect a leather combined with a foam layer, is produced by a “slush molding” process.

  Considering products such as soft interior panels using the above existing technology, there are some limitations. In particular, prior to the present invention, the manufacture of the parts required three different stages. Therefore, the amount of investment in equipment, operating space, energy consumption, and assembly time are increased, and a transport organization and a warehouse for stock parts before combination are required.

  In addition, it is not easy to recycle interior parts such as panels manufactured using different materials and different manufacturing techniques using the above-described existing technology. The layers of different polymer components that form the composite material need to be separated before reuse. Otherwise, the mechanical properties (for example, impact strength and elongation at break) of the recovered polymer will deteriorate, making it difficult to use even in lower applications. For this reason, the reuse of the composite material is expensive, complicated, and takes a long time.

German patent DE-A-10003595 WO96 / 33060 WO97 / 48537

  In particular, the performance required for a multilayer polymer material molding material used in automobile interiors is high, and in particular, the required performance of mechanical characteristics, surface characteristics, durability and odor characteristics is high. At present, various polymer materials are used for the production of automobile interior moldings.

  Also, the molded component must be very low density. Low density materials are preferred for improving fuel economy and obtaining desirable flexibility. Further, it is preferable that this molding composition has a very small amount of released volatile components, and the produced molding composition has preferable odor characteristics. Further, the hard layer needs to be strongly bonded to the foam layer.

  An object of the present invention is to provide an injection molding method for producing a multilayer molded material having a completely reusable structure, and a multilayer obtained from a recycled material having sufficient mechanical properties such as fracture elongation and impact strength. It is to provide a molding material.

The object is an injection molding process for producing a fully reusable multilayer product,
The multilayer is composed of i) a hard layer made of a thermoplastic polymer, and ii) a foamed skin layer made of a thermoplastic polymer compatible with the material of the hard layer,
a) a step of injection molding a hard layer into a mold having two surfaces;
b) floating one side of the mold or replacing one side of the mold to form a small gap of 3-4 mm between the hard layer and the floated or replaced mold surface; and c) step b). Injecting a foam skin layer into the gap formed in
It is achieved by a method characterized by comprising:

In one embodiment, the object is an injection molding method for creating a fully reusable multilayer body comprising:
Multi-layered
i) a hard layer made of a thermoplastic polymer, and ii) a foam skin layer made of a thermoplastic polymer compatible with the material of the hard layer,
d) injection molding a hard layer into a mold having two sides;
e) floating one side of the mold or replacing one side of the mold to form a small gap of 3-4 mm between the hard layer and the surface of the floated or replaced mold; and f) step e) An injection molding characterized by comprising a step of injecting a foam skin layer into the gap formed in step (b), and the thermoplastic polymer forming the hard layer and the reversible thermoplastic polymer forming the foam skin layer both contain polybutylene terephthalate. It is also achieved by the method.

  In this patent application, the compatibility between the material for producing the hard layer and the foamed skin layer means that the judged elongation of the composite composed of the hard layer and the foamed skin layer is 80% or more of the judged elongation of only the hard layer. It means that.

Description of Manufacturing Method Preferably, the injection molding method is performed using the following manufacturing method.

  The first preferred manufacturing technique relates to multi-layer molding and is performed in the following sequence of steps (depressurization technique is also used if necessary).

a) injection molding a hard layer made of a thermoplastic material (a dissolved gas or a chemical foaming agent may be used in combination),
b) floating one side of the mold or replacing one side to create a small gap preferably between 2 and 4 mm between the hard layer and the mold;
c) forming an in-mold decoration (IMD) skin layer film made of a thermoplastic polymer highly compatible with both the hard layer and the material used for the foam layer to improve surface properties;
d) injection molding a thermoplastic elastomer material that is compatible with the material used as the first layer together with the physical or chemical foaming agent in forming the foamed skin layer;
e) if necessary, repeating step b), expanding the gap to 10 to 400% of the original space until the desired foam density (foamed layer decompression molding),
f) If necessary, after the injection process, a foamed skin layer is overcoated or a solid surface layer having excellent surface quality and surface characteristics is formed by in-mold coating (IMP).

  In the overmolding process, the foam skin layer is formed of one kind of thermoplastic elastomer material.

  In the in-mold decoration (IMD) process, a skin layer film may be inserted into the mold as needed to improve surface characteristics.

  Further, in the in-mold coating (IMP) step, a coating material may be sprayed on the mold surface as necessary, and then a material for forming a layer may be added. After this step, the paint remains on the surface of the formed body. The paint may be colored or colorless. A transparent protective layer is usually sufficient for dashboards.

  The second manufacturing technique disclosed in the present invention is co-injection molding. This technique provides better results in terms of surface quality. The main advantage of this is that the core is completely separated from the skin layer. For this reason, the transfer to the surface of gas can be prevented.

  Also, by co-injection, the core part can be made as a pure structural material, which has a low density and inferior aesthetics, but can be made into an inexpensive foam layer part, while the skin part can have other functions and preferable surface characteristics.

  If necessary, co-injection and decompression techniques can be performed simultaneously to improve surface quality.

  In the co-injection process, the foam skin layer is formed from two different materials, a first material S for the skin layer and a second material F for the foam layer.

  The S substance is preferably a thermoplastic elastomer having good compatibility with the substance used in the foamed layer part and also compatible with the substance used in the layer, and the F substance is good in compatibility with the substance used in the skin layer part. , A physically or chemically foamed thermoplastic foam.

  The manufacturing method of the co-injection structure includes the following steps.

a) injection molding the hard layer (may include dissolved gas or chemical blowing agent)
b) floating one side of the mold or replacing one side of the mold to form a small gap of 2-12 mm between the hard layer and the surface of the floated or replaced mold, and c) if necessary For example, a process for inserting an in-mold decoration (IMD) skin layer film made of a thermoplastic polymer that is compatible with both the hard layer and the material used for the foam layer in order to improve surface properties.
d) A skin layer made of a thermoplastic material compatible with the material used for the hard layer is made incident to fill a part of the cavity, and then a foam layer (core material) is made incident to the initial skin layer. The process of infiltrating and starting co-injection (these two substances do not mix and the core does not jump out of the skin layer due to laminar flow. This foam layer part is also a thermoplastic material, if necessary It may be foamed with a dissolved gas or chemical foaming agent, or a skin material may be added during final processing of the part to completely enclose the core material).
e) if necessary, repeating step b) to expand the gap to 10% to 400% of the previous space to obtain a preferred bubble density (decompression molding of the foam layer);
f) A step of forming a solid surface layer having excellent surface quality and surface characteristics by coating the foamed skin layer or applying in-mold coating (IMP) after the injection step, if necessary.

  Various foaming technologies and additives are used in the plastics market to achieve low specific gravity, excellent skin surface appearance, and an excellent foamed skin layer foam structure.

  Current foaming technology has some obvious limitations, the largest of which is the large bubbles and the large variation in size. These defects can cause degradation of mechanical properties (eg, impact strength, brittleness, fatigue resistance) and appearance because the gas concentration and gas generation in the mold cannot be controlled.

  To overcome the above-mentioned problems, uniform nucleation is required, and in order to solve the problem as a uniform layer, a large amount of blowing agent or dissolved gas and high temperature and pressure are required.

  Two types of foaming techniques have been implemented using thermoplastic polymers.

i) Physical foaming Normal atmospheric gases such as carbon dioxide (CO ₂ ) and nitrogen (N ₂ ) are mixed into the material in the incident screw.

ii) Chemical foaming Normally, the foaming agent (CBA) decomposes and foams during the process. This chemical decomposition may be endothermic or exothermic. The endothermic foaming agent mainly generates CO ₂ and the exothermic foaming agent generates N ₂ . The chemical blowing agent (CBA) may be organic or inorganic. For example, azodicarbonamide (ADC); 4,4-oxybisbenzenesulfonyl hydrazide (OBSH); p-toluenesulfonyl hydrazide (TSH); 5-phenyltetrazole ( 5-PT); p-toluenesulfonyl semicarbazide (PTSS); dinitrosopentamethylenetetramine (DNPT); sodium hydrogen carbonate (SBC); zinc carbonate (ZnCO ₃ ) and the like.

An object of the present invention is to achieve excellent flexibility and appearance, low specific gravity (0.2 to 0.8 g / cm ³ ), and excellent bubble structure (uniformity of bubble size).

  Another important goal is to maximize the emission of volatile components (recent requirements of the automotive industry).

  Considering these requirements, most organic blowing agents are not preferred due to environmental concerns.

  The preferred foaming method in the present invention depends on the preferred thickness of the part. For example, in the case of large gaps, gaps exceeding approximately 100% (using reduced pressure molding of the foam layer), physical foaming is preferred. As a result of studying various methods, favorable results were obtained in two examples, both of which perform physical foaming, and the second method uses a chemical foaming agent in combination with the polymer.

The preferred solution is
a) Physically foaming the part while controlling the pressure level to mix the gas and material in a homogeneous phase. The most important factor in this process is the very high pressure level.

Under preferred conditions, the mixing pressure exceeds 350 bar and the concentration of atmospheric gases such as carbon dioxide (CO ₂ ) and nitrogen (N ₂ ) is high (0.1 to 2% by volume). The material temperature in the heating cylinder varies depending on the polymer used, but in order to obtain a preferable appearance and a correct foam structure, usually at 170 to 280 ° C., fine control of the opening ratio in the mold during decompression after injection of the foam layer is required. Measurement is required.

  b) Foaming agents are added at various concentrations to cause physical and chemical foaming. This method improves the surface properties while maintaining a preferred foam structure. This chemical blowing agent accelerates nucleation of the foamable material. The working conditions are the same as the above conditions a). Prior to this step, the plastic material and chemical blowing agent are mixed. A preferred foaming agent is a sodium carbonate-based additive (or other inorganic foaming agent), the amount of which is 0.1% to 3% by mass.

  Parts obtained by the above method have uniformly distributed microbubbles of uniform size (generally 20-100 microns in size, depending on material and processing conditions). The foamed material produced under the above conditions has a more uniform and more uniform cell structure and less VOC emissions than those obtained by other foaming methods. Other methods, for example, polymer microsphere shell encapsulated gas that increases in pressure and volume due to heating, have been studied, but the results are promising because of the short residence time and the decrease in density and the range of processing conditions is small. There wasn't.

  In the present invention, special skin layer characteristics such as special coloring and special scratch resistance may be required in some cases. Some of these requirements can be met by inserting an in-mold decorative skin film layer made of a thermoplastic polymer that is compatible with the hard and foam skin layers.

  This layer having a thickness similar to a film can be formed in various ways, for example by extrusion and / or film blow molding, the latter being preferred in terms of cost.

  Usually, no pre-processing of this layer film is necessary for reasons such as conversion techniques, material flexibility and compatibility with other layers.

  If the part shape has a short diameter or sharp corners, a portion of this film can be heated to improve the molding characteristics or to use a preformed film directly.

  In order to recycle the molding and to chemically bond the in-mold decorative skin layer film and the foam skin layer without adhesive or post treatment, this layer film is composed of a hard layer and a foam skin layer. It must be compatible with both materials.

  As noted above, it is possible to form this IMD layer film without using compatible materials, but preferably the same type of material should be used for the foam skin layer. However, properties such as hardness, color, and UV stability may be different.

  In this step, this layer film is inserted into the leather wrinkle surface side in the mold before foam layer injection.

  The thickness of this layer depends on the chamfering and angle of the leather wrinkle depth, the type of material and the shape of the molding.

  In order to realize cost reduction and one-shot process, the film should not be surface-treated, and the heat and pressure of the incident melt will take the shape necessary for the flat film and copy the mold surface. Let me.

  Here, the important operation control items are a material filling ratio and a mold temperature for appropriately stretching the film.

  Control items on other devices include the type and location of the gate, protruding from the core side, and the proper exhaust of air between the film and the substrate.

  Hereinafter, this process will be briefly described.

i) Use a roll or a robot to determine the position of the IMD layer film on the mold (you may use an appropriately cut flat film for insertion)
ii) vacuum or pressurize the cavity as necessary to maintain contact between the layer film and the mold surface;
iii) Injection into the mold from behind the foam layer, bonding the hard layer and the IMD layer film, and copying the layer film by surface treatment.

  When the IMD layer film is not formed after molding, it is usually deburred, the molded product is bent, and wound around the dividing line.

  The above-described method is a more environmentally friendly method than the coating method or the in-mold coating method, and satisfies the requirements regarding the skin characteristics and has flexibility in terms of surface appearance and cost reduction.

Materials Various thermoplastics can be used in the injection technology according to the present invention. Examples of preferable hard layer polymer, foamed skin layer polymer and IMD layer film polymer are shown below.

Preferably,
i) Hard layer polymer is PP, PBT, SMA, SAN, ABS, ABS / AMSAN blend, ABS / PC blend, ABS / PA blend, PBT / PET blend, PBT / ASA or PPE / HIPS blend. ,
ii) The foamed skin layer polymer is TPC / PBT, TPO, TPU or PVC.

More preferably,
i) the hard layer polymer is a fiber reinforced PBT / ASA blend;
ii) The foamed skin layer polymer is TPC / PBT or TPU.

More preferably,
i) the hard layer polymer is a fiber reinforced PP;
ii) Foam skin layer polymer, TPC / PBT or TPU.

Particularly preferably,
i) the hard layer polymer is a fiber reinforced ABS / PA blend;
ii) The foamed skin layer polymer is TPC / PBT or TPU.

In a preferred embodiment,
i) Hard layer is made of PP, SMA (styrene maleic anhydride), SAN (styrene acrylonitrile), ABS, PPE (polyphenylene ether) / HIPS blend, ABS / AMSAN (α-methyl-SAN) blend, ABS / PC (polycarbonate) ) Blends, or ABS / PA (polyamide) blends, PBT / ASA or PBT / PET blends,
Particularly preferably, it is PBT / ASA containing 0 to 30% by mass of glass, carbon or thermoplastic fiber,
Particularly preferably, it is ABS / PA containing 0 to 30% by mass of glass, carbon or thermoplastic fiber,
Particularly preferably, it is a SAN containing 10-50% by mass of glass fiber and SAN containing glass fiber,
Particularly preferred is PP containing 10 to 50% by mass of glass fiber long fibers.

In addition, it contains 10-40% by weight of a filler such as calcium stearate, talc or wollastonite, and ii) the foam skin layer is TPC / PBT (PF57804, page 16, defined in line 20 from the top), Manufactured by a material selected from the group consisting of TPO (thermoplastic polyolefin), TPU (thermoplastic polyurethane) or PVC, particularly preferably TPC / PBT or TPU.

  The most preferred embodiments are shown in the table below.

Hard layer:
The hard layer preferably contains 45 to 100% by mass of polybutylene terephthalate (PBT) as the A1 component, more preferably 55 to 90% by mass, and particularly preferably 80 to 90% by mass. In addition to PBT, an aromatic polyester may be used as the A2 component.

  In addition, aromatic polyester is a method known per se, and reaction of terephthalic acid, its esters or other ester-forming derivatives with 1,4-butanediol, 1,3-propanediol or 1,2-ethanediol. It is preferable to prepare by. Up to 20 mol% of terephthalic acid may be replaced with other dicarboxylic acids. Examples include naphthalenedicarboxylic acid, isophthalic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid and cyclohexanedicarboxylic acid, mixtures of these carboxylic acids, and ester-forming derivatives thereof. Up to 20 mol% of the dihydroxy compounds 1,4-butanediol, 1,3-propanediol and 1,2-ethanediol can also be replaced by other dihydroxy compounds, such as 1,6-hexanediol, Examples include 1,4-hexanediol, 1,4-cyclohexanediol, 1,4-di (hydroxy-methyl) cyclohexane, bisphenol A, neopentyl glycol, mixtures of these diols, and ester-forming derivatives thereof.

  Also included are resins formed from aromatic polyesters such as polytrimethylene terephthalate (PTT), especially polyethylene terephthalate (PET), terephthalic acid, propanediol and 1,4-butanediol. A part or all of the aromatic substance may be a recovered polyester material obtained from, for example, bottle material or bottle production waste. In particular, PBT and PBT / PET blends may be recovered polyesters and vehicle components are easily recyclable.

  In a particularly preferred embodiment, the A component is 70 to 100% by weight, preferably 80 to 100%, particularly preferably 90 to 100% by weight PBT, and 0 to 30% by weight, preferably 0 to 20%, particularly preferably. Contains 0-10% by weight of PET. More preferably, the component A does not contain PET.

  This novel molding composition has 0 to 25 mass%, preferably 3 as the B component of at least one particulate graft copolymer having a soft phase glass transition temperature of 0 ° C. or lower and a median particle size of 50 to 1000 nm. It is contained in an amount of ˜20 mass%, particularly preferably 10 to 15 mass%.

The component B is preferably
50 to 90% by mass of a glass transition temperature of a particulate graft base B1 having a temperature of less than 0 ° C., and 10 to 50% by mass of the following monomer b21) as a B21 component:
An aromatic vinyl monomer consisting of b22) as a B22 component of 50 to 90% by mass, and 10 to 50% by mass of acrylonitrile and / or methacrylonitrile,
Is a graft copolymer synthesized from

This particulate graft base B1 is obtained from 70 to 100% by weight of a C ₁ -C ₁₀ -alkyl acrylate and 0 to 30% by weight of a bifunctional monomer having two non-conjugated olefinic double bonds. May be used.

  In a preferred embodiment of the present invention, the graft base B1 is composed of the following monomers.

75 to 99.9% by weight of C ₁ -C ₁₀ -alkyl acrylate as B11 component,
0.1 to 10% by mass of at least one polyfunctional monomer having at least two non-conjugated olefinic double bonds as B12 component, and 0 to 24.9% by mass of one or more other components as B13 component Copolymerizable monomer.

  The graft base B1 is an elastomer having a glass transition temperature of preferably less than −20 ° C., particularly preferably less than −30 ° C.

  The main monomer B11 used for producing the elastomer is an acrylate having 1 to 10 carbon atoms, and particularly preferably 4 to 8 carbon atoms in the alcohol portion thereof. Particularly preferred monomers B11 include isobutyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate, with butyl acrylate being particularly preferred.

  In addition to the acrylate, the polyfunctional monomer having at least two non-conjugated olefinic double bonds as the crosslinkable monomer B12 is 0.1 to 10% by mass, preferably 0.1 to 5% by mass. Particularly preferably, it is used in an amount of 1 to 4% by weight. Examples include divinylbenzene, diallyl fumarate, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, tricyclodecenyl acrylate and dihydrodicyclopentadienyl acrylate, with the last being particularly preferred Two compounds.

In addition to the monomers B11 and B12, the structure of the graft base B1 may include other copolymerizable monomers up to 24.9% by mass, preferably up to 20% by mass, and preferable examples thereof. 1,3-butadiene, styrene, α-methylstyrene, acrylonitrile, methacrylonitrile and C ₁ -C ₈ -alkyl methacrylate, or a mixture of these monomers. In a particularly preferred embodiment, the graft base part B1 does not contain 1,3-butadiene, and the graft base part B1 comprises in particular only the B11 component and the B12 component.

  As grafts to graft base B1, there is graft B2 made of the following monomers.

As B21 component, 50-90 mass%, Preferably it is 60-90 mass%, Most preferably, it is 65-80 mass% aromatic vinyl monomer, and B212 component is 10-50 mass%, Preferably it is 10-40 % By weight, particularly preferably 20 to 35% by weight of acrylonitrile, methacrylonitrile, or mixtures thereof.

  Examples of aromatic vinyl monomers include unsubstituted and substituted styrenes such as α-methylstyrene, p-chlorostyrene and p-chloro-α-methylstyrene. Unsubstituted styrene and α-methylstyrene are preferable, and unsubstituted styrene is particularly preferable. In one embodiment of the invention, the median particle size of component B is 50-200 nm, preferably 55-150 nm.

  In another embodiment of the invention, the median particle size of component B is 200 to 1000 nm, preferably 400 to 550 nm.

  In another preferred embodiment of the present invention, the component B has a binomial particle size distribution and is 10 to 90% by weight, preferably 30 to 90% by weight, particularly preferably 50 to 75% by weight, and the median particle size is 50 to 50%. 200-nm, preferably 55-150 nm particulate graft copolymer, and 10-90% by weight, preferably 10-70% by weight, particularly preferably 25-50% by weight, with a median particle size of 250-1000 nm, preferably about Contains a coarse-grained graft copolymer of 400 to 550 nm.

The above median particle size and particle size distribution were determined from the integrated mass distribution. All median particle sizes described in the present invention are ponderial median particle sizes. These measurement methods are based on the ultracentrifugation analysis method (Kolloid-Z. And Z.-Polymere 250 (1972), p. 782-796) of W. Scholtan and H. Lange. By this ultracentrifugation measurement method, an integrated mass distribution of the diameters of the particles in the specimen is obtained. From this result, it is possible to calculate the mass% of particles having a diameter less than a specific size. The median (also referred to as a d ₅₀ of the integral mass distribution) particle diameter, d ₅₀ less the diameter of the particles means that there 50 mass%. To describe the width of the rubber particle size distribution, the integrated mass distributions d ₁₀ and d ₉₀ are used together with d ₅₀ (median particle diameter). The integrated mass distributions d ₁₀ and d ₉₀ are defined in the same way as d ₅₀ and correspond to 10 and 90 mass% particles, respectively. Coefficient Q:

は、粒度分布の幅の尺度である。本発明のＡ成分として使用可能なエマルジョンポリマーＡは、Ｑとして、０．５未満、特に好ましくは０．３５未満の値を持つ。

Is a measure of the width of the particle size distribution. The emulsion polymer A that can be used as the component A of the present invention has a value of Q of less than 0.5, particularly preferably less than 0.35.

  Graft copolymer B generally has one or more layers. That is, the polymer has a core and one or more shells. This polymer has a base (graft core) B1 and one or preferably two or more B2 shells (grafts) called grafts or graft shells grafted thereto.

  One or more graft shells can be formed on the rubber particles by grafting at least once. Each graft shell may be different. A graftable monomer and a polyfunctional crosslinkable monomer or a monomer containing a reactive group may be grafted together with these (see, for example, EP-A 0302282, DE-A 36014119, EP-A 0269861). .

  In one embodiment of the present invention, a crosslinked acrylate polymer having a glass transition temperature of less than 0 ° C. becomes the graft base B1. The glass transition temperature of the crosslinked acrylate polymer is preferably less than −20 ° C., particularly preferably less than −30 ° C.

  In principle, the structure of the graft copolymer can have two or more layers, of which at least one inner layer has a glass transition temperature of less than 0 ° C and the outermost layer has a glass transition temperature of more than 23 ° C. It is necessary to have.

  Preferably, graft B2 consists of at least one graft shell. Of these, the outermost graft shell is required to have a glass transition temperature exceeding 30 ° C. The polymer obtained from the monomer of graft B2 will have a glass transition temperature above 8 ° C.

  Examples of the method for preparing the graft copolymer B include emulsion polymerization, solution polymerization, bulk polymerization, and suspension polymerization. The graft copolymer B is preferably free-radical emulsified using a water-soluble and / or oil-soluble polymerization initiator such as peroxodisulfate or benzoyl peroxide, or a redox initiator at a temperature of 20 to 90 ° C. Adjust by polymerization. Redox initiators are also suitable for polymerization at temperatures below 20 ° C.

  Examples of preferred emulsion polymerization processes are disclosed in DE-A-2826925, DE-A-3149358 and DE-C-1260135.

  As described in DE-A-3227555, 314935.7, 3149358 and 3414118, the graft shell is preferably formed by emulsion polymerization. Specific values of the particle size of 50 to 1000 nm of the present invention are described in DE-C-1260135, DE-A2826925, or Applied Polymer Science, Vol. 9 (1965), p. 2929. The use of polymers with different particle sizes is described, for example, in DE-A 2826925 and U.S. Pat. S. Pat. No. 5,196,480.

  This novel molding composition contains 0.1 to 10% by mass of an existing additive as its component. Examples of this type of additive include UV stabilizers, transesterification stabilizers, oxidation inhibitors, lubricants, mold release agents, dyes, pigments, colorants, nucleating agents, antistatic agents, Antioxidants, heat stability improvers, light resistance improvers, hydrolysis resistance improvers, chemical resistance improvers, and thermal alteration preventives are exemplified, and lubricants that are particularly suitable for molding production are exemplified. These other additives may be added at any stage of the manufacturing process, but should be added as early as possible, so that the stable effect (or other specific effects) of the additive can be used early. It is preferable. The thermal stabilizer or oxidation inhibitor is usually a metal halide (chloride, bromide or iodide) derived from a metal of Group I of the Periodic Table of the Elements (eg Li, Na, K or Cu).

  Preferred stabilizers include sterically hindered phenols, vitamin E, and compounds having a similar structure. HALS stabilizers (hindered amine light stabilizers) are also preferred, and benzophenones, resorcinols, salicylic acids, benzotriazoles and other compounds (eg Irganox®, Tinuvin® 770 (HALS absorption) Agent, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate) or Tinuvin® P (UV absorber, (2H-benzotriazol-2-yl) -4-methylphenol), Tinuvin (registered trademark) and topanol (registered trademark)) are also preferable. These additions are usually at most 2% by weight per total mixture.

  Examples of preferred transesterification stabilizers include organic phosphonites such as tetrakis (2,4-di-ter-butylphenyl) bisphenylenephosphonite (Irgaphos (registered trademark) PEPQ, Ciba Geigy), monozinc phosphate ( Monohydrate or dihydrate). This transesterification stabilizer can be used, for example, in powder form or as a PBT masterbatch.

  Preferred lubricants and mold release agents include, for example, stearic acid, stearyl alcohol, stearic acid derivatives, higher fatty acids, derivatives thereof and mixtures of fatty acids having 12 to 30 carbon atoms. The amount of these additives is 0.05 to 1% by mass.

  Other additives include silicone oil, oligomeric isobutylene, and the like. The amount is usually 0.05 to 5% by mass. Pigments and dyes such as ultramarine, phthalocyanines, titanium dioxide, cadmium sulfide or perylene tetracarboxylic acid derivatives, and brighteners may be used.

  Processing aids and stabilizers such as UV stabilizers, lubricants and antistatic agents are usually used in an amount of 0.01 to 5% by weight per total molding composition.

  Nucleating agents such as talc, calcium fluoride, sodium phenylphosphinate, alumina or particulate polytetrafluoroethylene can be used in an amount of at most 5% by weight per total molding composition. Up to 5% by weight of plasticizer per molding composition, such as dioctyl phthalate, dibenzyl phthalate, butyl benzyl phthalate, hydrocarbon oil, N- (n-butyl) benzenesulfonamide, or o- or p-tolueneethyl It is also advantageous to add sulfonamides. Colorants such as dyes and pigments may be added in an amount of at most 5% by weight per molding composition.

  The thickness of the hard layer is preferably 1 to 10 mm, particularly preferably 1 to 4 mm.

Foamed skin layer and in-mold decorative layer film Thermoplastic polyester elastomer (TPC) containing polybutylene terephthalate (PBT) as a material for the foamed skin layer and in-mold decorative layer film that can be used in the production method of the present invention. Can be mentioned.

  This thermoplastic polyester elastomer (TPC) is a segmented copolyester consisting of a hard polyester segment and a soft polymer or oligomer soft segment that is nearly amorphous and has a glass transition temperature (Tg) below 0 ° C. When the soft segment is a polyether, this copolyester is called copolyetherester (TPC-ET), and when the soft segment is a polyester, this copolyester is called copolyesterester (TPC-ES) This copolyester is called TPC-EE when it contains ester and ether linkages.

  Such a segmented copolyester is considered to have a plurality of repeating long-chain ester units (soft segments) and short-chain ester units (soft segments) head-to-tail bonded to each other through ester-type bonds.

  This short chain unit has the general formula (I):

  The long chain ester unit is represented by the general formula (IIa) and / or (IIb):

(Where:
D represents a divalent group remaining after removal of a hydroxyl group from an alkylene glycol having a molecular weight of less than about 250;
R represents a divalent group remaining after the carboxyl group is eliminated from a dicarboxylic acid having a molecular weight of less than about 300;
G represents a divalent group remaining after removal of a hydroxyl terminal group from a long-chain glycol having a molecular weight of about 250 to about 6,000;
A represents a divalent group remaining after the carboxyl group is eliminated from the unsaturated or saturated long-chain dicarboxylic acid,
O represents oxygen).

  The “short chain ester unit” present in the polymer chain is a reaction in which a low molecular weight (less than about 250) diol (D) and a dicarboxylic acid form an ester unit represented by the general formula (I). Product. Low molecular weight diols used to form the short chain ester segment include acyclic, alicyclic, and aromatic dihydroxy compounds. Diols having 2 to 15 carbon atoms, such as ethylene glycol, propylene glycol, isobutylene glycol, tetramethylene glycol, pentamethylene glycol, 2,2-dimethyltrimethylene glycol, hexamethylene glycol, decamethylene glycol, dihydroxycyclohexane, cyclohexane Dimethanol, resorcinol, hydroquinone, 1,5-di-hydroxynaphthalene and the like are preferable. Particularly preferred are aliphatic diols having 2 to 8 carbon atoms. Aromatic dihydroxy compounds can also be used, examples of which include bisphenols such as bis- (p-hydroxy) diphenyl, bis (p-hydroxyphenyl) methane and bis (p-hydroxyphenyl) propane. Ester-forming derivatives of diols can also be used (for example, ethylene oxide or ethylene carbonate may be used instead of ethylene glycol). In the present invention, all derivatives suitable for ester formation should be considered to be included in this “low molecular weight diol”. However, the molecular weight conditions apply only to diols and not their derivatives. 1,4-Butanediol must be contained in the diol used.

  The dicarboxylic acid (R) that can be reacted with a low molecular weight diol or a long chain glycol in the production of the copolyester according to the present invention is an aliphatic, cycloaliphatic or aromatic low molecular weight, for example, less than about 300 molecular weight. Dicarboxylic acid is mentioned. The “dicarboxylic acid” in the present invention includes a dicarboxylic acid derivative that exhibits a behavior substantially similar to that of a dicarboxylic acid in a copolyester polymer forming reaction with a glycol or a diol. Such equivalent compounds include ester-forming derivatives such as esters, halides and anhydrides. However, this molecular weight condition applies only to acids, not to esters or ester-forming derivatives. Thus, the “dicarboxylic acid” is an ester of a dicarboxylic acid having a molecular weight greater than about 300, or a dicarboxylic acid equivalent having a molecular weight greater than about 300 if the corresponding acid has a molecular weight of less than about 300. Also good. These dicarboxylic acids may have one or more substituents as long as they do not adversely affect the formation of the copolyester polymer and use as a polymer in the final product of the present invention. In the present invention, “aliphatic dicarboxylic acid” refers to a carboxylic acid having two carboxyl groups, both of which are bonded to a saturated carbon atom. When the carbon atom to which the carboxyl group is bonded is a saturated atom contained in the ring, this acid is a cycloaliphatic carboxylic acid. The “aromatic dicarboxylic acid” in the present invention is a dicarboxylic acid having two carboxyl groups. When there are two or more rings, it is not necessary for both carboxyl groups to be bonded to the same aromatic ring, and also a divalent aliphatic or aromatic group, or a divalent group such as -O -Or -SO2- may be linked. Each carboxyl group may be bonded to an independent aromatic ring or condensed aromatic ring.

Examples of aromatic dicarboxylic acids used include phthalic acid, isophthalic acid and terephthalic acid, dibenzoic acid; for example, 4,4′-diphenyldicarboxylic acid, bis (para-carboxyphenyl) methane, paraoxy (para-carboxyphenyl) Benzoic acid, ethylenebis (paraoxybenzoic acid), 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, phenanthenedicarboxylic acid, anthracene dicarboxylic acid, 4,4-sulfonyldibenzoic acid Dicarboxylic acid compounds having two benzene rings such as acids and their (C ₁ -C ₁₂ ) -alkyl derivatives; halogenated derivatives (eg F, Cl, Br), (preferably C _1-4- ) Examples include ring-substituted derivatives such as alkoxy derivatives and aryl derivatives.

  When (aromatic) dicarboxylic acid coexists, an aromatic acid having a hydroxy group, for example, para- (β-hydroxyethoxy) -benzoic acid may be used.

  In the production of the copolyester according to the present invention, the acid is preferably an aromatic dicarboxylic acid.

  Among the aromatic acids, those having 8 to 16 carbon atoms are preferable, and phenylene dicarboxylic acid, that is, phthalic acid, isophthalic acid, and terephthalic acid are particularly preferable. In particular, terephthalic acid alone or a mixture of terephthalic acid and isophthalic acid is preferable.

  The acid used must contain terephthalic acid.

  The “long chain ester unit” is a unit represented by the formula (IIb) which is a reactive product of a long chain dicarboxylic acid and a low molecular weight diol.

Long chain dicarboxylic acid (A) is a fatty acid dimer. This fatty acid dimer is known and refers to a dimerization product of a monounsaturated or polyunsaturated fatty acid. The alkyl chain of the dimer acid as preferably C ₁₀ -C _30, still more preferably dimeric fatty acid with C ₁₂ -C _24, particularly preferably C ₁₄ -C _22, and particularly preferably C _18, for example, oleic acid , Linoleic acid, linolenic acid, palmitoleic acid, elaidic acid, erucic acid dimer. Dimerization products of unsaturated fatty acid mixtures obtained by hydrolysis of natural fats and oils (eg, sunflower oil, soybean oil, olive oil, rapeseed oil, cottonseed oil and tall oil) may be used.

  Among these dimer acid products, hydrogenated dimer acid products are preferable, and purified hydrogenated dimer fatty acids are particularly preferable.

Examples of the long-chain glycol (G) suitable for producing the polymer according to the present invention include polyethylene oxide) glycol, poly (1,2- and -1,3-propylene oxide) glycol, and poly (tetramethylene oxide) glycol. Poly (pentamethylene oxide) glycol, poly (hexamethylene oxide) glycol, poly (heptamethylene oxide) glycol, poly (octamethylene oxide) glycol, poly (nonamethylene oxide) glycol, poly (decamethylene oxide) glycol, and poly (1,2-butylene oxide) poly (alkylene oxide) glycols such as glycol [wherein "alkylene" preferably C _2-10 - alkylene]; random copolymers of ethylene oxide and 1,2-propylene oxide Polymers obtained by reaction of formaldehyde with glycols such as formaldehyde and glycols such as pentamethylene-glycol or mixtures of tetramethylene glycol and pentamethylene glycol; dicarboxymethyl acids of polyalkylene oxides, for example Derivatives from poly (tetramethylene oxide) or esters thereof. Moreover, you may use polyisoprene glycol, polybutadiene glycol, these copolymers, and what hydrogenated these as long chain polymer glycol. Further, glycol esters of dicarboxylic acid obtained by oxidation of a polyisobutylene-diene copolymer may be used as a raw material. Preferred long-chain glycols include, for example, poly (tetramethylene oxide) glycol having a number average molecular weight of 600 to 4000, polyethylene oxide having a number average molecular weight of 1000 to 3000, and / or poly (1,2- and -1, 3-propylene oxide) glycol.

  In the present invention, poly (tetramethylene oxide) glycol is particularly preferred. This long chain glycol also includes dimerized aliphatic diols obtained by hydrogenation of high purity dimer fatty acids and mixtures of poly (alkylene oxide) glycols and dimer aliphatic diols. Among dimer diol products, those obtained by hydrogenation of high purity dimer fatty acids are preferred.

  The ratio of soft and hard segments in the copolyester can vary greatly, but should preferably be selected such that the resulting copolyetherester has a relatively low hardness. Preferably, the copolyetherester has a Shore D hardness of less than 50, more preferably less than 40. More preferably, the Shore D hardness is 20 to 40. In general, when the hardness of the copolyetherester is low, the low temperature performance and flexibility of the laminate product obtained by the method of the present invention will be improved.

  The short chain ester unit represented by the formula (I) occupies about 10 to 95% by mass, preferably about 10 to 55% by mass, and more preferably about 13 to 40% by mass of the present copolyester. This is because the polymer exhibits a favorable balance between elasticity and toughness in this region. The remainder of the copolyester is long chain ester units (represented by formula (IIa) or (IIb)), about 5-90% by weight of the copolyester, preferably 45-90% by weight and more preferably 60-87. Occupies mass%.

  Preferred copolyester elastomers used in the composition for the foamed skin layer and the in-mold decorative film layer of the present invention are, for example, dimethyl terephthalate, 1,4-butanediol and a number average molecular weight of about 600 to 4000, more preferably. Manufactured from about 1000 to 2000 poly (tetramethylene oxide) glycol and / or polyethylene oxide having a molecular weight of about 1000 to 3000) and / or poly (1,2- and -1,3-propylene oxide) glycol It is an elastomer.

  Particularly preferred is Pibiflex® thermoplastic polyester (P group, Italy). Among the Pibiflex copolyesters, those having a Shore D hardness of less than 40 are preferred as components of the present invention.

Another object of the present invention is to
i) a hard layer made of a thermoplastic polymer, and ii) a foamed skin layer made of a thermoplastic polymer compatible with the material of the hard layer,
Consists of
Both the thermoplastic polymer forming the hard layer and the thermoplastic polymer forming the skin layer contain polybutylene terephthalate,
The hard layer is 45 to 100% by weight of polybutylene terephthalate as the A1 component,
0 to 30% by mass of polyethylene terephthalate as A2 component, and 0 to 25% by mass of ASA copolymer as B component,
To provide a completely reusable multilayer product characterized in that

Yet another purpose is
i) a hard layer made of a thermoplastic polymer, and ii) a foamed skin layer made of a thermoplastic polymer compatible with the material of the hard layer,
Consists of
Both the thermoplastic polymer that forms the hard layer and the thermoplastic polymer that forms the skin layer contain polybutylene terephthalate, and the thermoplastic polymer that forms the foamed skin layer has multiple repeating long-chain ester units as soft segments and multiple Of repeating short chain ester units as a hard segment,
The short chain unit is represented by the general formula (I):

  The long chain ester unit is represented by the general formula (IIa) and / or (IIb):

(Where:
D represents a divalent group remaining after removal of the hydroxyl group from an alkylene glycol having a molecular weight of less than about 250, and 1,4-butane-diol is at least part of the alkylene glycol used;
R represents a divalent group remaining after the carboxyl group is eliminated from a dicarboxylic acid having a molecular weight of less than about 300, and terephthalic acid is at least part of the dicarboxylic acid used;
G represents a divalent group remaining after the terminal hydroxyl group is eliminated from a long-chain glycol having a molecular weight of about 250 to about 6,000,
A represents a divalent group remaining after the carboxyl group is eliminated from an unsaturated or saturated long-chain dicarboxylic acid having 1 to 25 carbon atoms;
O represents oxygen) to provide a completely reusable multilayer.

Preferably, the hard layer is
45 to 100% by mass of polybutylene terephthalate as the A1 component,
0 to 30% by mass of polyethylene terephthalate as A2 component, and 0 to 25% by mass of ASA copolymer as B component,
Including
The thermoplastic polymer forming the foam skin layer comprises a plurality of repeating long chain ester units as a soft segment and a plurality of repeating short chain ester units as a hard segment;
The short chain unit is represented by the general formula (I):

The long chain ester unit is represented by the general formula (IIa) and / or (IIb):

(Where
D represents a divalent group remaining after removal of the hydroxyl group from an alkylene glycol having a molecular weight of less than about 250, and 1,4-butane-diol is at least part of the alkylene glycol used;
R represents a divalent group remaining after the carboxyl group is eliminated from a dicarboxylic acid having a molecular weight of less than about 300, and terephthalic acid is at least part of the dicarboxylic acid used;
G represents a divalent group remaining after the terminal hydroxyl group is eliminated from a long-chain glycol having a molecular weight of about 250 to about 6,000,
A represents a divalent group remaining after the carboxyl group is eliminated from an unsaturated or saturated long-chain dicarboxylic acid having 1 to 25 carbon atoms;
O represents oxygen).

Uses and Examples The novel molding composition is excellent in heat resistance, heat aging resistance, mechanical properties, and surface properties, and therefore can be used as an extremely wide variety of moldings. Examples include camera cases, cell phone cases, binocular tube sections, steam exhaust hood steam ducts, pressure cooker parts, hot air grills and pump housings.

  Due to the properties described above, the new molding is particularly suitable for automotive applications.

  In particular, examples of new moldings produced from this new molding composition include light switch housings, central electrical wiring housings, multi-point connectors, plug connectors, ABS controller housings, identification plates, roof racks, etc. Parts.

  Since this new molded article is excellent in injection performance, it is particularly suitable for automobile interior use. Applications of the new moldings with this new molding composition include protective covers, storages, dashboard carriers, door chests, central console parts, and radio and air conditioning system storage, central console covers, radio covers, air Harmonization system and ash tray, central console extension, storage pocket, driver side and passenger door storage area, central console storage area, driver and passenger seat components such as seat covers, defroster duct, internal mirror housing , Sunroof parts such as sunroof frames, equipment cover / protection parts, equipment sockets, upper and lower covers for steering pillars, air ducts, air blowers and personal air flow conditioner adapters, defroster ducts, door side covers, knee parts Cover, air discharge nozzle, defroster opening Switches and levers, and an air filter ducts and ventilation ducts, and these reinforced component thereof. The above applications are merely possible examples in automotive interior applications. It is particularly preferable that the new molded product can be marked with a laser.

  Examples of other applications include exterior body parts, especially fenders, tailgates, side panels, bumpers, panels, identification plate supports, panels, sunroofs, sunroof frames, and impact protectors and their parts. It is done.

  Applications other than the automotive field of molded products include boat hulls, lawn mower housings, garden furniture, motorcycle parts, camera cases, mobile phone cases, binocular tube parts, steam ducts for steam exhaust hoods, pressure cooker parts, hot air grills A housing and a pump housing are mentioned.

  This molding composition is particularly useful for molding plug connectors and housing parts, and particularly for large-sized vehicle-mounted electronic parts, specifically for ABS / ASC, ESP transmission systems, seats, mirror motors, windows. It is useful as an electronic component for vertical motors, for openable / closable roofs, for airbag operation, passenger seat safety, acceleration sensors, ignition electronic components, and seat usage status confirmation. Other preferred uses of this new molding composition include locking system housings, wiper auto-relays and cover housings, key housings and the like. Other uses of the moldings produced from this new molding composition include gas meter housings, wind deflectors, drive motor housings where use of drive motors is preferred in automobiles, drive motor housings, power drill components, heater components (particularly Heat insulation, furnace knobs and handles), screen wiper parts (especially for holding wiper blades), spoilers, mirror trays for automotive mirrors, and cleaning device control system housings.

  The new molding composition is also suitable as a molding for households, particularly kitchens. For example, a baking machine, a toaster, a table grill, a cooking machine, an electric canner, a juice press, etc. are mentioned. In these products, switches, housings, handles, covers, etc. may be made from this new molding composition. This new molding composition can be used for moldings such as range handles, preferably range handles, range knobs and switches.

  A molded product with a large surface area is thin in place of the surface area, and thus excellent moldability is required. However, the new molding composition may be effective for producing a molded product with a large surface area. I know it. Specific examples of moldings with such a large surface area include sunroof rails, exterior body parts, air introduction grills, dashboard parts such as dashboard carriers, protective covers, air ducts, additional parts (especially for central consoles, small items) ) And the tachometer protection frame is raised.

  It is particularly preferable to use the multilayer structure of the present invention in an automobile interior.

  Hereinafter, the present invention will be described in detail by way of examples.

Example 1
Multi-layer molding method (over injection technique)
Foam skin layer Material: Pibiflex (registered trademark) 2567S (P group, Italy) (Chemical component: TCP-ET (ISO1043))
Processing conditions for direct injection molding of foam skin layer:
Melting temperature about 230 ° C
Mold temperature about 70 ℃
Injection speed 80mm / min
Tightening force 200KN
No back pressure

Hard layer Material: Ultradur® S4090QX (BASF) (68 wt% PBT, 17 wt% ASA, 15 wt% glass fiber)

Hard layer processing conditions Melting temperature 270 ℃
Mold temperature about 70 ℃
Injection speed 30mm / min
Tightening force 2500kN
Back pressure 20 bar

  Ultradur (registered trademark) was injected into a disk mold having a diameter of about 300 mm and a gap between two surfaces of 2 mm. The mold was opened 2 mm, and Pibiflex (registered trademark) was injected. Immediately after filling, the mold was further opened by 3 mm. Thus, it was made to foam with dissolved gas. The final thickness of the foam layer was 5 mm.

The Pibiflex (registered trademark) layer was formed using Pibiflex (registered trademark) containing 0.6% by volume of N ₂ with respect to the total Pibiflex (registered trademark). N ₂ was introduced into the Pibiflex® material contained in the heated cylinder of the extruder under a pressure of about 300 bar. The temperature of the heating cylinder was 220 ° C to 260 ° C.

Example 2
The same processing conditions and polymer material as in Example 1 were used. However, physical and chemical foaming agents were shared.

  The same processing conditions as in Example 1 were used for physical foaming. However, Pibiflex (registered trademark) material was previously blended with 1.5% by mass of sodium carbonate-based additive Hydrocerol (registered trademark) CF40E (P group company, Italy), which is a chemical foaming agent.

  The multilayer product thus obtained had favorable flexibility. Interlayer adhesion was good.

  The adhesive strength between the hard layer and the soft layer of the moldings of Example 1 and Example 2 reached at least 20 N / cm, but the conventional interlayer adhesive strength using SMA (styrene-maleic anhydride) / urethane foam. Was at most about 10 N / cm.

  In contrast to conventional polymer combinations, this molding could be recovered without the need to sort out different polymers. This is because the above-described method only uses one type of substance.

  The main advantage is that the molded product obtained by crushing and reinjection has excellent mechanical properties. For example, in the case of flexibility, the elongation at break maintains a value corresponding to about 80% of the original.

Claims (21)

An injection molding method for producing a fully reusable multilayer product,
The multilayer is composed of i) a hard layer made of a thermoplastic polymer and ii) a foamed skin layer made of a thermoplastic polymer compatible with the material of the hard layer,
A step of injection molding a hard layer into a mold having two surfaces;
A step of floating one side of the mold or replacing one side of the mold to form a small gap of 3 to 4 mm between the hard layer and the surface of the floated or replaced mold, and a foam skin in the formed gap Injecting a layer,
An injection molding method characterized by comprising: An injection molding method for producing a fully reusable multilayer product,
The multilayer is composed of i) a hard layer made of a thermoplastic polymer and ii) a foamed skin layer made of a thermoplastic polymer compatible with the material of the hard layer,
A step of injection molding a hard layer into a mold having two surfaces;
A step of floating one side of the mold or replacing one side of the mold to form a small gap of 3 to 4 mm between the hard layer and the surface of the floated or replaced mold, and a foam skin in the formed gap Injecting a layer,
And a thermoplastic polymer that forms a hard layer and a reversible thermoplastic polymer that forms a foamed skin layer both contain polybutylene terephthalate. i) The hard layer comprises PP, PBT, SMA, SAN, ABS, ABS / AMSAN blend, ABS / PC blend, ABS / PA blend, PBT / PET blend, PBT / ASA or PPE / HIPS blend, and ii 3. The injection molding method according to claim 2, wherein the foamed skin layer is made of TPC / PBT, TPO, TPU, or PVC. The injection molding method according to claim 2, wherein i) the hard layer is made of a fiber reinforced PBT / ASA blend, and ii) the foamed skin layer is TPC / PBT or TPU. The injection molding method according to claim 1, wherein i) the hard layer is made of fiber reinforced PP, and ii) the foamed skin layer is made of TPC / PBT or TPU. The injection molding method according to claim 1, wherein i) the hard layer is made of a fiber reinforced ABS / PA blend, and ii) the foamed skin layer is made of TPC / PBT or TPU.   The injection molding method according to claim 1, wherein the foamed skin layer is formed by overmolding.   The foamed skin layer is obtained by co-injecting a first thermoplastic material containing a foaming agent and a second thermoplastic material not containing a foaming agent to form a foamed layer portion and a skin layer portion, respectively. The injection molding method according to any one of 1 to 6.   The skin of the foam skin layer is composed of a hard layer and an in-mold decorative film layer that is compatible with the thermoplastic polymer of the foam layer. The in-mold decorative film layer is inserted into the mold after the hard layer is injected. The method according to claim 1, wherein the foam layer is injected after the insertion of the in-mold decorative film layer. The hard layer is
45 to 100% by mass of polybutylene terephthalate as the A1 component,
0 to 30% by mass of polyethylene terephthalate as A2 component, and 0 to 25% by mass of ASA copolymer as B component,
10. The method according to any one of claims 1-4 and 7-9, comprising: The hard layer is
The injection molding method according to claim 10, comprising 80 to 90% by mass of polybutylene terephthalate as the A1 component, and 10 to 15% by mass of ASA copolymer as the B component. The B component is
Particulate graft base B1: consisting of 50 to 90% by weight of the following monomers:
Alkyl acrylate 75 to 99.9% by weight of C ₁ -C ₁₀ as B11 component,
0.1 to 10% by mass of at least two non-conjugated olefinic double bonds as B12 component, and 0 to 24.9% by mass of one or more other B13 components Graft B2 comprising the following monomer grafted to 10 to 50% by weight of graft base B1:
50 to 29 mass% aromatic vinyl monomer as B21 component, and 10 to 50 mass% acrylonitrile and / or methacrylonitrile as B22 component,
The method according to claim 10 or 11, comprising:   13. A method according to claim 12, wherein the hard layer is reinforced with 5-30% glass, carbon or thermoplastic fibers.   The method according to claim 1, wherein the foamed skin layer has a thickness of 1 to 12 mm. The thermoplastic polymer forming the foamed skin layer has a plurality of repeating long-chain ester units as a soft segment and a plurality of repeating short-chain ester units as a hard segment, and the short chain unit has the following general formula (I ):

The long chain ester unit is represented by the general formula (IIa) and / or (II):

(Where
D represents a divalent group remaining after elimination of a hydroxyl group from an alkylene glycol having a molecular weight of less than about 250, and is at least part of the alkylene glycol used by 1,4-butane-diol;
R represents a divalent group remaining after the carboxyl group is eliminated from a dicarboxylic acid having a molecular weight of less than about 300, and terephthalic acid is at least part of the dicarboxylic acid used;
G represents a divalent group remaining after the terminal hydroxyl group is eliminated from a long-chain glycol having a molecular weight of about 250 to about 6,000,
A represents a divalent group remaining after the carboxyl group is eliminated from an unsaturated or saturated long-chain dicarboxylic acid having 1 to 25 carbon atoms;
The method according to claim 1, wherein O represents oxygen. i) a hard layer made of a thermoplastic polymer, and ii) a foam skin layer made of a thermoplastic polymer compatible with the material of the hard layer,
The thermoplastic polymer forming the hard layer and the thermoplastic polymer forming the skin layer are both fully reusable multilayers comprising polybutylene terephthalate,
The hard layer is 45 to 100% by weight of polybutylene terephthalate as the A1 component
A multilayer product comprising 0 to 30% by mass of polyethylene terephthalate as the A2 component, and 0 to 25% by mass of ASA copolymer as the B component. i) a hard layer made of a thermoplastic polymer, and ii) a foam skin layer made of a thermoplastic polymer compatible with the material of the hard layer,
Both the thermoplastic polymer forming the hard layer and the thermoplastic polymer forming the skin layer contain polybutylene terephthalate, and the thermoplastic polymer forming the foamed skin layer has a plurality of repeating long-chain ester units as a soft segment, and A fully reusable multilayer comprising a plurality of repeating short chain ester units as hard segments,
The short chain unit is represented by the general formula (I):

The long chain ester unit is represented by the general formula (IIa) and / or (IIb):

(Where:
D represents a divalent group remaining after removal of the hydroxyl group from an alkylene glycol having a molecular weight of less than about 250, and 1,4-butane-diol is at least part of the alkylene glycol used;
R represents a divalent group remaining after the carboxyl group is eliminated from a dicarboxylic acid having a molecular weight of less than about 300, and terephthalic acid is at least part of the dicarboxylic acid used;
G represents a divalent group remaining after the terminal hydroxyl group is eliminated from a long-chain glycol having a molecular weight of about 250 to about 6,000,
A represents a divalent group remaining after the carboxyl group is eliminated from an unsaturated or saturated long-chain dicarboxylic acid having 1 to 25 carbon atoms;
O represents oxygen). The hard layer is
45 to 100% by mass of polybutylene terephthalate as the A1 component,
0 to 30% by mass of polyethylene terephthalate as A2 component, and 0 to 25% by mass of ASA copolymer as B component,
Including
The thermoplastic polymer forming the foam skin layer comprises a plurality of repeating long chain ester units as a soft segment and a plurality of repeating short chain ester units as a hard segment;
The short chain unit is represented by the general formula (I):

The long chain ester unit is represented by the general formula (IIa) and / or (IIb):

(Where
D represents a divalent group remaining after removal of the hydroxyl group from an alkylene glycol having a molecular weight of less than about 250, and 1,4-butane-diol is at least part of the alkylene glycol used;
R represents a divalent group remaining after the carboxyl group is eliminated from a dicarboxylic acid having a molecular weight of less than about 300, and terephthalic acid is at least part of the dicarboxylic acid used;
G represents a divalent group remaining after the terminal hydroxyl group is eliminated from a long-chain glycol having a molecular weight of about 250 to about 6,000,
A represents a divalent group remaining after the carboxyl group is eliminated from an unsaturated or saturated long-chain dicarboxylic acid having 1 to 25 carbon atoms;
The fully reusable multilayer product according to claim 16 or 17, characterized in that O represents oxygen).   The method to use the multilayer object of any one of Claims 16-18 in a motor vehicle interior.   The method of claim 19, wherein the vehicle interior is a dashboard.   The method according to claim 19, wherein the vehicle interior is a car seat.