JP4781219B2 - Polyamide resin injection welded molding - Google Patents

Description

  The present invention relates to a welded molded article excellent in welding strength, in which at least two polyamide resin molded articles are integrated by injection welding.

Polyamide resins are widely used in the fields of automobiles, machines, electrical and electronic products, miscellaneous goods, etc. by utilizing their excellent moldability, heat resistance, toughness, oil / gasoline resistance, wear resistance and the like.
Polyamide resins are used in these applications by forming them into various desired shapes by injection molding, extrusion molding, blow molding, compression molding, etc. Recently, with the improvement in performance and miniaturization of parts, etc. The shape is complicated, and the number of cases in which molding is difficult by a simple one-time molding process is increasing.
For this reason, it is necessary to produce a plurality of polyamide resin molded bodies, join them by some method, and use them in an integrated manner.

Conventionally, in such a case, after molding a plurality of molded bodies in advance, they are bonded by an adhesive, chemical treatment, etc., welded by hot pressing, vibration heating, laser heating, etc., or fastened by bolts and screws. The method etc. which were integrated by equalizing etc. were taken.
However, these methods have problems such as complicated processes, many restrictions on shape, and poor economic efficiency.

On the other hand, as a method for improving these problems, there is a welding molding method by injection welding (hereinafter, abbreviated as injection welding method).
This is done by inserting a preformed primary molded body into the mold and further molding a new shape to the primary molded body by injection molding a thermoplastic resin. This is a technique in which the secondary molded body is welded and integrated with heat during injection molding. Further, this method is made more rational by a molding method called die slide injection, which enables the molding of the primary molded body and the molding and welding of the secondary molded body with one mold.
Although the injection welding method is simple and extremely excellent in productivity, it has been actively studied. On the other hand, the strength at the welded portion of the molded body integrated by the injection welding method, that is, the welding strength is low. In reality, it is a problem that only a part of the industrialized example by the injection welding method is used.
In addition, in the injection welding method, when the primary molding material and the secondary molding material are the same type of polyamide resin composition, a level of welding strength that can be determined to be usable for some products is achieved. In the case of polyamide resin compositions of different types, the welding strength is extremely low, which is far from solving the problem.

For example, in applications such as wheel parts such as carts and armrest parts of chairs, the quality required for the core and the surface layer is completely different.
That is, the core portion is required to have high rigidity and strength, and the surface layer is required to have excellent impact resistance, absorb vibration, or have good touch and flexibility.
As a polyamide resin composition for achieving these objects, a polyamide resin reinforced with a filler is used for a portion having high rigidity and strength, and an elastic polymer is used for a portion requiring impact resistance and flexibility. However, it has a problem that welding strength is extremely reduced by welding them by injection molding.

Filler-reinforced polyamide resin compositions aimed at improving these injection weld strengths are being actively studied.
For example, in Patent Document 1,
“(A) Injection welding containing 40 to 95% by weight of polyamide copolymer comprising 2 to 25% by weight of polyamide 6 component and 98 to 75% by weight of polyamide 66 component, and (B) 5 to 60% by weight of inorganic filler. Materials "have been proposed.
In Patent Document 2,
“(A) 0.1 to 50 parts by weight of a polyolefin-based resin and (C) 10 to 150 parts by weight of glass fibers are blended with 100 parts by weight of a nylon resin. Resin composition "is disclosed.
However, in any of the proposals and disclosures, the improvement level of the welding strength is still insufficient, and the applicable range as a material and welding technology for manufacturing complex parts has been limited to a very small part.

JP-A-8-337718 JP 2001-11307 A

Accordingly, an object of the present invention is to provide a polyamide resin molded body in which the problem of insufficient welding strength in a molded body obtained by welding and integrating the above-described polyamide resin molded body by an injection welding method.
In particular, a combination that has been expected to have a high industrial utility value but has conventionally been difficult to develop a high welding strength by an injection welding method, that is, a flexible material in which the primary molding material contains an elastic polymer. A molded product formed by welding and integrating by an injection welding method with a combination of a polyamide resin composition excellent in heat resistance and impact resistance, and a combination of an inorganic filler reinforced polyamide resin composition whose secondary molding material is excellent in rigidity and dimensional stability. Is intended to develop a high welding strength.

  As a result of studies to achieve the above object in the polyamide resin injection welding technique, the present inventors blended a saponified ethylene / vinyl acetate copolymer with a predetermined proportion of the secondary molding material in the polyamide resin. As a composition, it has been found that the welding strength of the injection-molded molded product can be dramatically improved even when the primary molding material and the secondary molding material are different, and the present invention has been achieved.

The present invention is as follows.
The following secondary molding material, which is different from the primary molding material, is injection-molded on the surface of one or more primary moldings made of the following primary molding material, and the primary molding and the molded body portion made of the secondary molding material are welded together. A welded molded body integrated by
(1) Thermoplastic elasticity in which the primary molding material has a glass transition temperature of −20 ° C. or less as a thermoplastic polymer other than component (B): polyamide resin with respect to 100 parts by weight of component (A): polyamide resin A polyamide resin composition containing 5 to 100 parts by weight of a polymer ;
(2) Secondary molding material is component (C): 0.1 to 40 parts by weight of saponified ethylene / vinyl acetate copolymer and component (E) with respect to 100 parts by weight of polyamide resin (E) ): A polyamide resin injection-welded molded article characterized by being a polyamide resin composition containing 0 to 200 parts by weight of an inorganic filler.

  The polyamide resin injection welded molded article of the present invention has extremely high welding strength and excellent mechanical properties, appearance, etc., so various nylon resin parts for automobiles, electrical and electronic equipment, mechanical parts, miscellaneous goods, etc., especially complicated It is suitable for manufacturing a nylon resin part having a shape.

Hereinafter, the present invention will be described in detail.
Polyamide Resin Injection Welded Molded Article The polyamide resin injection welded molded article of the present invention is manufactured through two stages of primary molding and secondary molding. In the present invention, various known molding methods such as injection molding, extrusion molding, and press molding can be employed for primary molding, and a primary molded body used for the next secondary molding is prepared. Further, in the secondary molding, injection molding is adopted, and the polyamide resin injection welded molding of the present invention is completed. Specifically, on the surface of the prepared primary molded body, a secondary molding material in which the specific component (D) is blended is melt-injected, and a molded body portion (hereinafter referred to as the following) composed of the primary molded body and the secondary molding material. There is no particular limitation as long as it is a method capable of producing a molded body in which only this portion is referred to as a “secondary molded body”). The molding material used here is not particularly limited as long as the primary molding material and the secondary molding material are polyamide resin compositions having different constituent components and / or blending ratios.
In the present invention, the polyamide resin injection welded molded body is usually produced by the following method [1] or [2].

[1] Insert molding method of primary molded body In this method, a primary molded body molded in advance by one of the various molding methods described above is inserted into a mold mounted on an injection molding machine for secondary molding, A molding method in which a predetermined secondary molding material is injected into the cavity after being placed in a predetermined position and the mold is closed, and a secondary molded body is formed, and simultaneously welded and integrated with the primary molded body. is there.
In this method, the number of primary molded bodies installed in the cavity may be two or more as long as the desired adhesive strength is achieved. As for the position, the shape of the injection-welded molded body of the present invention and / or the selection of whether the surface of the primary molded body to be welded as the integrated secondary molded body is the entire surface or a part of the limited part, and further integrated There is also an advantage that it can be designed freely depending on the selection of the shape of the secondary formed body.

[2] Die slide injection method This method is a method in which a primary molded body and a secondary molded body are injection-molded in two stages using the same mold, and in the first stage, in a mold mounted on an injection molding machine. The primary molding material is injected into the primary molding cavity to form a plurality of primary molded bodies, the solidified sprue and the runner material are removed, and then the primary molded body is usually released from the mold. Without moving, the movable mold that is slidably moved is moved to a predetermined position, and in the second stage, the movable mold that holds the primary molded body at the predetermined position is configured between the fixed mold and the movable mold. This is a molding method in which a secondary molding material is injected into a secondary molding cavity to form a secondary molded body, and simultaneously welded and integrated with the primary molded body. An example of a mold that can be used in this method is disclosed in Japanese Patent Application Laid-Open No. 62-87315.
In this method, there is an advantage that it is possible to save labor for releasing the primary molded body from the mold.

Component (A) and Component (C): Polyamide Resin In the present invention, the component (A) polyamide resin constituting the primary molding material and the component (C) polyamide resin constituting the secondary molding material are both A polyamide resin obtained by polycondensation of polymerizable ω-amino acids or lactams thereof, preferably lactams having 3 or more ring members, or dibasic acids and diamines.

  Specific examples of the ω-amino acids include ε-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid and the like. Specific examples of the lactam include ε-caprolactam, enantolactam, capryllactam, lauryllactam, α-pyrrolidone, α-piperidone and the like.

  Specific examples of the dibasic acids include adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecadioic acid, hexadecadioic acid, hexadecenedioic acid, and eicosandioic acid. Eicosadienedioic acid, diglycolic acid, 2,2,4-trimethyladipic acid, xylylene dicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid and the like.

  Next, specific examples of the diamines include hexamethylene diamine, tetramethylene diamine, nonamethylene diamine, undecamethylene diamine, dodecamethylene diamine, 2,2,4 (or 2,4,4) -trimethylhexamethylene. Examples include diamine, bis- (4,4′-aminocyclohexyl) methane, and metaxylylenediamine.

The polyamide resin obtained from these raw materials is preferably polyamide 6 mainly composed of ε-caprolactam or ε-aminocaproic acid, polyamide 66 mainly composed of equimolar salt of hexamethylenediamine and adipic acid, hexamethylene Examples thereof include polyamide 6/66 copolymers mainly composed of equimolar salts of diamine and adipic acid and ε-caprolactam or ε-aminocaproic acid.
These polyamide resins may be used by blending a plurality of types.

In the present invention, the polyamide resin of component (A) in the primary molding material and the polyamide resin of component (C) in the secondary molding material may be the same polyamide resin or different types of polyamide resins. Moreover, the usage-amount of a component (A) and the usage-amount of a component (C) may differ depending on the structure of the target welding molded object.
However, when another type of polyamide resin is used, the relationship between the melting point (mpA) of the polyamide resin of component (A) and the melting point (mpC) of the polyamide resin of component (C) is preferably within the following range. .
mpC-100 ° C. ≦ mpA ≦ mpC + 50 ° C.
More preferably, mpC-30 ° C. ≦ mpA ≦ mpC + 10 ° C.
More preferably, mpC−25 ° C. ≦ mpA ≦ mpC + 5 ° C.
If mpA is higher than mpC by 50 ° C. or higher than 100 ° C. or lower than 100 ° C., the solidification timing at the time of welding does not match, and it becomes difficult to improve the welding strength.
As the most preferable polyamide resin, it is preferable that both the component (A) and the component (C) are polyamide resins of the same type and further have excellent welding strength.

The polyamide resin preferably has a viscosity number in the range of 70 to 190 ml / g measured at a polyamide resin concentration of 1 wt% in a 96 wt% concentrated sulfuric acid at a temperature of 23 ° C. according to ISO-307 (JIS K6933). If the viscosity number is less than 70 ml / g, the rigidity, dimensional stability, impact resistance and appearance are inferior, and if it exceeds 190 ml / g, the moldability is inferior and the appearance is deteriorated. The terminal group concentration is preferably such that the terminal carboxyl group content is 100 μeq / g or less, and if it is higher than 100 μeq / g, the fluidity is remarkably lowered. The ratio of the terminal carboxyl group content to the terminal amino group content (terminal carboxyl group content / terminal amino group content) is preferably in the range of 0.2 to 5. Outside this range, the appearance deteriorates, which is not preferable.
An example of the method for adjusting the terminal group is shown in JP-A No. 61-163935.

Component (B): Thermoplastic polymer other than polyamide The primary molding material of the present invention has improved impact resistance, improved dimensional stability, improved water absorption characteristics, and coating adhesion within the range not impairing the object of the present invention. If necessary, a thermoplastic polymer other than the polyamide resin can be blended as the component (B) into the polyamide resin as the component (A) as necessary. The component (B) is not particularly limited as long as it is a thermoplastic polymer other than a polyamide resin, and may be a single type or a plurality of types.
Specifically, in addition to the thermoplastic elastic polymer described later, polystyrene, polyethylene, polypropylene, acrylic resin, polycarbonate, polybutylene terephthalate, polyethylene terephthalate, modified polyphenylene ether, polyphenylene sulfide, liquid crystal polyester, acrylonitrile / butadiene / styrene. Various thermoplastic polymers such as terpolymers of
In addition, component (D) saponified ethylene / vinyl acetate copolymer, which is essential to be blended into the secondary molding material described later, is one type, but the welding strength is improved simply by being included in the primary molding material. Cannot be expected.

The amount of component (B), the polyamide resin 100 parts by weight of component (A), in the range of 5 to 100 parts by weight, good Mashiku 10 to 100 parts by weight. Although the physical properties can be improved by blending the component (B), when the component (B) is blended in an amount exceeding 100 parts by weight, it becomes difficult to express the welding strength.

Blending of thermoplastic elastic polymer In the present invention, it is particularly possible to blend various thermoplastic elastic polymers and elastic polymers having a glass transition temperature of −20 ° C. or lower to prevent the primary molded body from being resistant. Since impact property can be improved, it can be preferably used. When the glass transition temperature is −30 ° C. or lower, a significant improvement is possible.

  Usually, there is a concern that the blending of these elastic polymers will greatly reduce the injection weld strength, but in combination with the secondary molding material blended with the component (D) of the present invention, a high weld strength can be exhibited. Therefore, it can be used suitably. A preferable blending amount for improving impact resistance is in the range of 5 to 100 parts by weight, more preferably in the range of 10 to 80 parts by weight with respect to 100 parts by weight of the polyamide resin as the component (A).

  The elastic polymer having a glass transition temperature of −20 ° C. or lower used in the present invention has a glass transition temperature (here, defined as a temperature obtained by the DSC method in accordance with JIS K7121) of −20 ° C. or lower. Is.

  Examples of preferable elastic polymers include (B-1) aromatic vinyl hydrocarbon-conjugated diene block copolymers or hydrogenated products thereof, (B-2) ethylene-α-olefin copolymers, and the like. It is done.

Two or more elastic polymers having a glass transition temperature of −20 ° C. or lower can be used in combination. Elastomers obtained by graft reaction or copolymerization of various unsaturated carboxylic acids and / or their derivatives and vinyl monomers may be preferably used for some or all of them.
In this case, the amount of the unsaturated carboxylic acid and / or its derivative or vinyl monomer grafted or copolymerized with respect to the entire elastic polymer is preferably 0.05 to 5% by weight. Examples of the unsaturated carboxylic acid used in the graft reaction or copolymerization include acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, and butenedicarboxylic acid. Examples of the derivatives thereof include alkyl esters, glycidyl esters, esters having di- or tri-alkoxysilyl groups, acid anhydrides or imides, and among these, glycidyl esters, di- or tri-alkoxys. Unsaturated carboxylic acid ester, acid anhydride, and imide having a silyl group are more preferable. Examples of vinyl monomers include aromatic vinyl compounds such as styrene, vinyl cyanide compounds such as acrylonitrile, vinylsilane compounds such as vinyltrimethoxysilane, and these unsaturated carboxylic acids or derivatives thereof. Alternatively, two or more vinyl monomers may be used in combination. In addition, about the method of graft-reacting these unsaturated carboxylic acid or its derivative (s), or a vinyl monomer, the copolymerization method by a well-known radical initiator can be used.

(B-1): Block copolymer or hydrogenated product thereof A block copolymer of the component (B-1) used in the primary molding material of the present invention or a hydrogenated product thereof is a vinyl aromatic compound polymer block. a block copolymer of a and a conjugated diene compound polymer block b or a hydrogenated product thereof. The hydrogenated product is a block copolymer in which the number of aliphatic unsaturated bonds in the block b is mainly reduced by hydrogenation. The arrangement of the block a and the block b includes a linear structure or a branched structure (radial teleblock). Further, some of these structures may contain a random chain derived from a random copolymerized portion of a vinyl aromatic compound and a conjugated diene compound. Among these structures, those having a linear structure are preferable, those having an aba type triblock structure are particularly preferable in terms of impact resistance, and those having an ab type diblock structure are included. Also good.

  The monomer constituting the vinyl aromatic compound polymer block a of component (B-1) and the vinyl aromatic compound are preferably styrene, α-methylstyrene, paramethylstyrene, vinyl toluene, vinyl xylene, and the like. More preferably, it is styrene. The monomer and conjugated diene compound constituting the conjugated diene compound polymer block b are preferably 1,3-butadiene and 2-methyl-1,3-butadiene. The proportion of the repeating units derived from the vinyl aromatic compound in these block copolymers or hydrogenated products thereof is preferably in the range of 10 to 70% by weight, more preferably in the range of 10 to 40% by weight.

  Among the block copolymers of component (B-1) or hydrogenated products thereof, hydrogenated products are preferably used from the viewpoint of thermal stability, and the unsaturated bond of the hydrogenated product of the block copolymer is seen. Of the aliphatic unsaturated bonds derived from the conjugated diene compound, the proportion remaining without being hydrogenated is preferably 20% or less, and more preferably 10% or less. Further, about 25% or less of the aromatic unsaturated bond derived from the vinyl aromatic compound may be hydrogenated. As the hydrogenated product of such a block copolymer, when the monomer constituting the conjugated diene compound polymer block b and the conjugated diene compound are 1,3-butadiene, styrene-ethylene / butylene- It is called a styrene copolymer (SEBS), and in the case of 2-methyl-1,3-butadiene, it is called a styrene-ethylene / propylene-styrene copolymer (SEPS), and has various aba types. The triblock structure is commercially available and easily available.

(B-2): Ethylene-α-olefin copolymer The component (B-2) ethylene-α-olefin copolymer used in the primary molding material of the present invention is an essential component of ethylene and α-olefin. A rubbery copolymer. The weight ratio of ethylene to α-olefin is usually 90:10 to 20:80, preferably 75:25 to 40:60. The α-olefin used for copolymerization is an unsaturated hydrocarbon compound having 3 to 20 carbon atoms. Specific examples include propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 3 -Methylbutene-1, 4-methylpentene-1, etc. are mentioned, Preferably it is a C3-C10 linear alpha olefin, Especially preferable are propylene, 1-butene, and 1-octene.

  Moreover, as an ethylene-alpha-olefin type | system | group copolymer of the component (B-2) used by this invention, what introduce | transduced the diene compound other than ethylene and the said alpha olefin can be used. The types of diene compounds used are alkenyl norbornenes, cyclic dienes, and aliphatic dienes, preferably 5-ethylidene-2-norbornene and dicyclopentadiene.

  As these ethylene-α-olefin copolymers, the melt flow rate (MFR) (230 ° C., load 2.16 kg: ISO-1133) is preferably in the range of 0.05 to 200 g / 10 minutes, and 0.1 to 50 g. A range of / 10 minutes is more preferable. If the MFR value is lower than 0.05 g / 10 min, the molding processability is inferior, and if it is 200 g / 10 min or more, the impact resistance is inferior.

Component (D): in saponified present invention ethylene-vinyl acetate copolymer, the saponified et styrene-vinyl acetate copolymer essential containing component of the secondary molding material (D), ethylene-vinyl acetate copolymer A part or all of the vinyl acetate component of the polymer is saponified and converted into a vinyl alcohol component, and the saponified one is also called an ethylene / vinyl alcohol copolymer. These various saponification products are commercially available, for example, from Kuraray Co., Ltd. under the product name “EVAL” and from Nippon Synthetic Chemical Co., Ltd. under the trade name “Soarnol”.
The copolymerization ratio of ethylene in component (D) is preferably in the range of 10 to 98 mol%, particularly preferably in the range of 30 to 90 mol%. When the ethylene copolymerization ratio exceeds 98 mol%, the effect of improving the welding strength decreases, and when the ethylene copolymerization ratio is less than 10 mol%, the thermal stability of the resin composition becomes poor and the flexibility becomes poor. .

The saponification degree of the vinyl acetate component in the saponified ethylene / vinyl acetate copolymer is preferably 40 mol% or more from the viewpoint of welding strength. When the saponification degree is lower than 40 mol%, the thermal stability at the time of melting of the resin composition is also insufficient.
The saponification degree is usually 80 mol% or more, more preferably 90 mol% or more, and most preferably an ethylene / vinyl alcohol copolymer. The saponified ethylene / vinyl acetate copolymer having such a composition has an MI measured in accordance with JIS-K6730 (190 ° C. × 2.16 kg) of 0.5 to 300 g / 10 minutes, preferably 0.8 to The thing of 250 g / 10min is suitable from a viewpoint of the melt fluidity and strength of the resin composition.

  The above-mentioned ethylene / vinyl acetate copolymer may contain a small amount of a copolymerizable monomer component. Examples of copolymerizable monomer components include propylene, isobutene, α-octene, α-dodecene, α-olefins such as α-octadecene, unsaturated carboxylic acids or salts thereof, partial alkyl esters, complete alkyl esters, acrylonitrile, Examples include acrylamide, anhydrides, unsaturated sulfonic acids or salts thereof.

  The compounding quantity of a component (D) is 0.1-40 weight part with respect to 100 weight part of components (C). If the blending amount of component (D) is less than 0.1 parts by weight, the welding strength of the resulting injection-welded molded article cannot be substantially improved. On the other hand, when the amount is more than 40 parts by weight, the reaction with the polyamide resin of the component (C) proceeds at the time of heating and melting, and the melt fluidity of the secondary molding material is lowered. A particularly preferred amount of component (D) is 1 to 25 parts by weight.

Ingredient (E): Inorganic filler In the present invention, the inorganic filler of ingredient (E) can be blended as necessary for adjustment of rigidity, impact resistance, dimensional stability and heat resistance. The blending amount is usually 0 to 200 parts by weight, preferably 1 to 150 parts by weight, more preferably 2 to 120 parts by weight with respect to 100 parts by weight of the polyamide resin of component (C). is there.
Usually, there is a concern that these blends may reduce the welding strength, but the blending amount of the component (D) of the secondary molding material of the present invention can be suitably used because it exhibits a high welding strength.

  As the inorganic filler of component (E) used in the secondary molding material of the present invention, generally known inorganic fillers for plastics can be used. Specifically, glass-based fillers (glass fiber, pulverized) Glass fiber (milled fiber), glass flake, glass bead, etc.), mica, talc, kaolin, wollastonite, potassium titanate whisker, carbon fiber, basalt fiber, etc., and two or more of them may be used in combination. . The combined use of wollastonite is preferable because of excellent surface appearance of the molded product. That is, it is necessary to select the type of filler according to the required characteristics of the molded product.

The glass-based filler is preferable in terms of mechanical properties, flame retardancy, and economy, and a glass-based filler made of E glass having a low alkali content and good electrical properties is particularly preferable.
In particular, in the secondary molding material of the present invention, the glass fiber is blended at a ratio of 10 to 150 parts by weight with respect to 100 parts by weight of the polyamide resin of the component (C), so that rigidity, dimensional stability, and welding strength are obtained. It is preferable because a molded article excellent in the above can be obtained. If it exceeds 150 parts by weight, not only is it difficult to develop high welding strength, but the appearance is also deteriorated, which is not preferable. A particularly preferable blending amount when blending the glass fiber is 10 to 120 parts by weight from the balance of mechanical properties, appearance, and the like.

  The inorganic filler is preferably treated with a surface treatment agent or a sizing agent from the viewpoint of welding strength and mechanical strength. Therefore, it is necessary to select a surface treatment agent or a sizing agent treatment in balance with mechanical strength, molding surface smoothness, and the like.

Examples of the surface treatment agent or sizing agent include chlorosilane compounds such as vinyltrichlorosilane and methylvinyldichlorosilane, alkoxysilanes such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, and methacryloxypropyltrimethoxysilane. Compounds, epoxy silane compounds such as (epoxycyclohexyl) ethyltrimethoxysilane, glycidoxypropyltrimethoxysilane, acrylic compounds, isocyanate compounds, titanate compounds, epoxy compounds, aminosilane compounds, urethane compounds, etc. Is mentioned.
The average fiber diameter of the glass fiber which is one of the inorganic fillers of the component (E) preferably used in the present invention is in the range of 1 to 30 μm, and the average fiber length in the state dispersed in the resin is 50 to 10,000 μm. It is a range.
Outside this range, it is difficult to develop a high welding strength, and any of rigidity, impact property, and appearance is deteriorated.

  In the polyamide resin composition, which is the primary molding material and / or secondary molding material, used in the production of the injection-bonded molded body of the present invention, a heat stabilizer such as a copper compound is included within the range not impairing the effects of the present invention. Further, known additives such as mold release agents, flame retardants, antistatic agents, colorants such as carbon black and nigrosine may be blended.

Preparation of the polyamide resin composition which is a primary molding material and / or a secondary molding material can be carried out according to a conventional method at any stage from resin polymerization to molding.
For example, a method in which all components constituting the primary molding material and / or the secondary molding material are melt-kneaded using an extruder, a method in which only some components are blended by dry blending, a specific component is blended in a high concentration A method for preparing and blending a master batch is also possible.
In particular, melt-kneaded resin composition pellets other than component (D) are produced with a twin-screw extruder, and the pellet or powder of component (D) is blended by dry blending to form a polyamide resin composition as a secondary molding material The method of preparing the product is preferable because the welding strength can be enhanced.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to a following example, unless the summary is exceeded.

[Raw materials used]
Component (A) and Component (C): Polyamide resin Polyamide 6 resin (manufactured by Mitsubishi Engineering Plastics, trade name: NOVAMID 1013J), viscosity number based on ISO-307: 138 ml / g, melting point: 223 ° C Terminal amino group concentration: 27 μeq / g, Terminal carboxyl group concentration: 56 μeq / g (abbreviated as PA6)
Component (B): Thermoplastic elastic polymer (B-1) Hydrogenated copolymer of styrene / ethylene / butadiene / styrene graft-modified with maleic anhydride (trade name: Tuftec M1943, manufactured by Asahi Kasei), styrene content : 20 wt%, aba type triblock structure, glass transition temperature: −30 ° C. or lower (abbreviated as mSEBS)
(B-2) Ethylene / butene-1 copolymer grafted with maleic anhydride (Mitsubishi Chemical Corporation, trade name: MODIC-AP730T), glass transition temperature: −50 ° C., density: 0.89 g / cm ³ , MFR: 2 g / 10 min [measured at ASTM-D1238, 230 ° C., load 2.16 kg] (abbreviated as mEBR)
Component (D): Saponified ethylene / vinyl acetate copolymer Ethylene vinyl alcohol resin (manufactured by Kuraray Co., Ltd., trade name: Eval G156A), ethylene copolymerization ratio = 47 mol%, degree of saponification: 100 mol% Specific gravity = 1.12, MI = 6 g / 10 min [Measured at JIS-K6730, 190 ° C., load 2.16 kg] (abbreviated as EVOH)
Ingredient (E): Inorganic filler E glass fiber chopped strand (manufactured by NEC Glass, trade name: ECS03T283H), average fiber diameter: 10.5 μm, average fiber length: 300 μm, surface treatment agent: aminosilane / urethane compound ( (Abbreviated as GF)

[Examples 1-3 and Comparative Examples 1-3]
Preparation of primary molding material:
The component (B) is blended with the component (A) at the ratio shown in Table 1 below, and the temperature is set using a twin-screw extruder (manufactured by Nippon Steel Works, trade name: TEX-30 XCT). The composition was obtained by melt-kneading under the conditions of 240 ° C. and screw rotation speed: 200 rpm.
The obtained polyamide resin composition was vacuum-dried at 120 ° C. for 8 hours to obtain a primary molding material.

Preparation of secondary molding material:
First, in Examples 1-2 and Comparative Examples 1-2, the component (E) was blended with the component (C) in the ratio shown in Table 1, and a twin-screw extruder (manufactured by Nippon Steel Works, Ltd., product) Name: TEX-30 XCT) was melt kneaded under the conditions of a preset temperature: 240 ° C. and a screw rotation speed: 200 rpm to obtain a composition.
Next, in Examples 1 and 2, pellets of the component (D) are shown in Table 1 immediately before molding in the obtained composition, and in Example 3, the component (C). The dry blend was blended at a proper ratio.
Further, in Examples 1 to 3 or Comparative Examples 1 and 2, the polyamide resin composition obtained by the above dry blend or melt kneading is used, and in Comparative Example 3, the component (C) is 120 ° C. Was vacuum dried for 8 hours to obtain a secondary molding material.

Quality assessment of primary and secondary molding materials:
For the polyamide resin composition of the primary molding material and the secondary molding material, for quality evaluation, a predetermined test piece according to ISO standard is molded by injection molding, a bending test and an impact resistance test are performed, and the result is obtained. It described in Table-1.
The molding conditions of the ISO test piece are as follows: Injection molding machine: manufactured by FANUC (model: α100iA),
Cylinder temperature: 250 ° C
Mold temperature setting: 80 ° C
Injection time: 20 sec
Cooling time: 20 sec.
The bending test measured bending strength and bending elastic modulus based on ISO-178 standard.
In the impact resistance test, Charpy impact strength (notched) was measured based on ISO-179 standard. In the Charpy impact test, when it did not break, it was described as NB (non-breaking).

Manufacture of injection welded compacts:
An example of producing a tensile test piece for evaluating the welding strength will be described below.
The test piece formed by injection welding is a type I tensile test piece according to the ASTM-D638 standard (the tensile test piece is divided from the center between the marked lines so as to be symmetrical in the thickness direction. The two parts (the dividing surface is a rectangle of 13 mm × 3.2 mm) are referred to as test piece 1 and test piece 2), and details of the molding method are as follows.

[Primary molding]
First, using a mold having a cavity in which the shape of the test piece 1 was engraved, the polyamide resin composition of the primary molding material shown in Table 1 was melt-injected to obtain the test piece 1 as a primary molded body.
The molding machine was manufactured by Nippon Steel Works (model: J75ED), cylinder temperature: 250 ° C., mold temperature: 40 ° C., injection time: 20 sec, cooling time: 20 sec.
The obtained primary molded body was stored in an aluminum bag until secondary molding, so as not to absorb water.

[Secondary molding]
After inserting the test piece 1 obtained by the above primary molding into a predetermined position in a mold having a cavity in which the shape of a type I tensile test piece conforming to the ASTM-D638 standard is engraved, In the corresponding remaining space, the polyamide resin composition of the secondary molding material shown in Table-1 is melt-injected, and the test piece 2 is additionally molded into the test piece 1 by welding to form ASTM as an injection-welded molded article. A tensile specimen was obtained.
The molding machine was manufactured by Nippon Steel Works (model: J75ED), cylinder temperature: 270 ° C., mold temperature: 80 ° C., injection time: 15 sec, cooling time: 15 sec.

Evaluation of the welding strength of the injection welded molded body was performed as follows.
[Measurement of injection welding strength]
A tensile test piece of type I conforming to the ASTM-D638 standard, which is an injection-welded molded body obtained by the above secondary molding, is pulled and broken under the conditions of a tensile speed of 5 mm / min and a distance between chucks of 115 mm based on the standard. The load was measured. Since all the fractures occurred at the welded portion, this breaking load is shown in Table 1 as the welding strength.

From the results in Table 1, the following can be understood.
The primary molding materials of Examples 1 to 3 and Comparative Examples 1 to 3 are excellent in impact resistance.
The secondary molding materials in Examples 1 and 2 and Comparative Examples 1 and 2 are excellent in rigidity and strength.
In addition, the injection-welded molded body of Example 1-3 has a welding strength that is 3 to 5 times higher than that of Comparative Example 1-3 that does not include the component (D), and exhibits an extremely high welding strength. .

The injection-welded molded body produced according to the present invention exhibits extremely high welding strength, so that it becomes possible to produce parts having complicated shapes, small parts, etc., which have been difficult to produce in the past. By changing the composition of the primary molding material and the secondary molding material, it is possible to express different preferable characteristics for each portion of the welded molding.
Taking advantage of this advantage, it is effective as a welded molded body for various applications such as mechanical parts such as sunroof casing pipes of automobiles, design products such as multicolor molded articles, and parts such as caster wheels.

Claims (5)

The following secondary molding material, which is different from the primary molding material, is injection-molded on the surface of one or more primary moldings made of the following primary molding material, and the primary molding and the molded body portion made of the secondary molding material are welded together. A welded molded body integrated by
(1) Thermoplastic elasticity in which the primary molding material has a glass transition temperature of −20 ° C. or less as a thermoplastic polymer other than component (B): polyamide resin with respect to 100 parts by weight of component (A): polyamide resin A polyamide resin composition containing 5 to 100 parts by weight of a polymer ;
(2) Secondary molding material is component (C): 0.1 to 40 parts by weight of saponified ethylene / vinyl acetate copolymer and component (E) with respect to 100 parts by weight of polyamide resin (E) ): A polyamide resin injection-welded molded article characterized by being a polyamide resin composition containing 0 to 200 parts by weight of an inorganic filler. 2. The polyamide resin injection molded article according to claim 1, wherein the saponification degree of the component (D) is 40% or more. The injection-molded product made of polyamide resin according to claim 1 or 2 , wherein the compounding amount of component (E) is 1-150 parts by weight per 100 parts by weight of polyamide resin of component (C). . The component (E) is a glass-based filler, and the polyamide resin injection-welded molded article according to any one of claims 1 to 3 . The polyamide resin injection-welded molded article according to any one of claims 1 to 4 , wherein both the component (A) and the polyamide resin of the component (C) are polyamide 6.