JP5493283B2 - Two-color molded thermoplastic polyurethane resin composition for plating, two-color molded body for plating, two-color molded body for plating, and methods for producing them - Google Patents

Description

  The present invention relates to a thermoplastic polyurethane resin composition for plating two-color molding (hereinafter sometimes referred to as “TPU”), a two-color molding for plating, a two-color molding for plating, and a method for producing them.

  The two-color molded body with plating is obtained by integrating a molded body made of a hard component with a plated layer and a molded body made of a soft component without a plated layer. Such a plated two-color molded body is used for, for example, a push button key switch used for inputting electronic equipment such as a home phone, a mobile phone, and a POS terminal. Such a two-color molded body with plating is manufactured by, for example, integrating a molded body made of a hard resin such as a polycarbonate resin and a molded body made of a rubber-like elastic body such as silicone rubber using an adhesive. It was. However, when producing a two-color molded body with plating in this way, it is necessary to integrate the molded body made of a rubber-like elastic body after the plating layer is formed on the molded body made of a hard resin. There was a problem of high cost.

  In order to solve such a problem, for example, Japanese Patent Application Laid-Open No. 2002-184259 (Patent Document 1) discloses a first molded body made of a hard resin and a second made of a soft resin such as a urethane-based thermoplastic elastomer. A method for producing a two-color molded body with plating is disclosed in which a plating process is performed on a two-color molded body obtained by integrating the molded body with the first molded body to form a plating layer only on the first molded body. Yes. However, in the method of manufacturing a two-color molded body with plating as described in Patent Document 1, the surface of the second molded body on which the plating layer is not formed is eroded by the plating process, and the second molded body is discolored. There was a problem that.

  On the other hand, the applicant, Japan Polyurethane Industry Co., Ltd., in International Publication No. 2004/106401 pamphlet (Patent Document 2), has organic diisocyanate (A) containing hexamethylene diisocyanate as the main component and polycarbonate diol as the main component. A molded body (keypad) made of a thermoplastic polyurethane resin containing a polymer polyol (B) and a chain extender (C) mainly composed of an aliphatic diol having 2 to 10 carbon atoms is disclosed. However, the thermoplastic polyurethane resin disclosed in Patent Document 2 is for obtaining a keypad having excellent secondary moldability, oleic acid resistance, weather resistance, and transparency. The correlation between was not clear.

In the two-color molded products with plating, a wide variety of thermoplastic elastomers such as styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, polyester-based thermoplastic elastomers, and urethane-based thermoplastic elastomers are used as soft resins. Among such a large number of thermoplastic elastomers, those skilled in the art can use or utilize the thermoplastic polyurethane resin described in Patent Document 2 for the development of a thermoplastic polyurethane resin composition for plating two-color molding. However, it was never easy to recall.
JP 2002-184259 A International Publication No. 2004/106401 Pamphlet

  The present invention has been made in view of the above-described problems of the prior art, and in a two-color molded article for plating provided with a first molded article made of a hard resin and a second molded article made of a soft resin, Thermoplastic polyurethane resin composition for plating two-color molding, capable of obtaining a two-color molding for plating having sufficient resistance to plating treatment, in which discoloration due to the plating treatment in the molding made of resin is sufficiently suppressed, and for plating An object is to provide a two-color molded body, a two-color molded body with plating, and a method for producing them.

  As a result of intensive studies to achieve the above object, the inventor of the present invention has obtained a second two-color molded article for plating comprising a first molded article made of hard resin and a second molded article made of soft resin. By using a very limited specific TPU as the resin component used in the molded article, discoloration due to the plating treatment in the molded article made of a soft resin is sufficiently suppressed, and the plating two-color molded article having sufficient plating treatment resistance Has been found, and the present invention has been completed.

That is, the two-color molded TPU with plating of the present invention comprises a first molded body made of a hard resin having a Rockwell hardness of R80 or more and a second molded body made of a soft resin. A two-color molded TPU for use in the second molded body,
And f Kisa organic diisocyanate mainly comprising diisocyanate (a1) (A), a polymer polyol (B) mainly composed of a polycarbonate diol (b1), the aliphatic diol having 2 to 10 carbon atoms (c1) Containing a chain extender (C) as a main component ,
Content of the said hexamethylene diisocyanate (a1) is 70 mass% or more with respect to the total mass of organic diisocyanate (A),
The content of the polycarbonate diol (b1) is 70% by mass or more based on the total mass of the polymer polyol (B),
The number average molecular weight of the polymer polyol (B) is 500 to 5,000,
The content of the aliphatic diol (c1) is 70% by mass or more based on the total mass of the chain extender (C).
And it is characterized in and this.

The two-color molded body for plating according to the present invention includes a first molded body made of a hard resin having a Rockwell hardness of R80 or more, and
A polymer polyol formed on at least a part of the surface of the first molded body, the organic diisocyanate (A) containing hexamethylene diisocyanate (a1) as a main component and the polycarbonate diol (b1) as a main component. (B), and Ri TPU Tona containing a chain extender mainly composed of an aliphatic diol having 2 to 10 carbon atoms (c1) (C), the content of organic diisocyanates of the hexamethylene diisocyanate (a1) It is 70 mass% or more with respect to the total mass of (A), content of the said polycarbonate diol (b1) is 70 mass% or more with respect to the total mass of a high molecular polyol (B), and the said high molecular polyol ( The number average molecular weight of B) is 500 to 5000, and the content of the aliphatic diol (c1) is 7 with respect to the total mass of the chain extender (C). It is characterized in further comprising a second molded body Ru der mass% or more.

Furthermore, the method for producing a two-color molded article for plating according to the present invention includes a step of preparing a first molded article made of a hard resin having a Rockwell hardness of R80 or more,
Mainly organic diisocyanate (A) mainly composed of hexamethylene diisocyanate (a1), polymer polyol (B) mainly composed of polycarbonate diol (b1), and aliphatic diol (c1) having 2 to 10 carbon atoms. A chain extender (C) as a component, the content of the hexamethylene diisocyanate (a1) is 70% by mass or more based on the total mass of the organic diisocyanate (A), and the polycarbonate diol (b1 ) Is 70% by mass or more based on the total mass of the polymer polyol (B), the polymer polyol (B) has a number average molecular weight of 500 to 5,000, and the aliphatic diol (c1). contact of content chain extenders 70 mass% or more der Ru TPU with respect to the total weight of (C), at least a portion of said first molded body A step by state molding while maintaining, obtaining a second molded body said first molded body of at least a portion of is formed on the surface of plating two-color molding body made of the TPU was,
It is the method characterized by including.

Moreover, the two-color molded body with plating of the present invention is a first molded body made of a hard resin having a Rockwell hardness of R80 or more,
A polymer polyol formed on at least a part of the surface of the first molded body, the organic diisocyanate (A) containing hexamethylene diisocyanate (a1) as a main component and the polycarbonate diol (b1) as a main component. (B), and Ri TPU Tona containing a chain extender mainly composed of an aliphatic diol having 2 to 10 carbon atoms (c1) (C), the content of organic diisocyanates of the hexamethylene diisocyanate (a1) It is 70 mass% or more with respect to the total mass of (A), content of the said polycarbonate diol (b1) is 70 mass% or more with respect to the total mass of a high molecular polyol (B), and the said high molecular polyol ( The number average molecular weight of B) is 500 to 5000, and the content of the aliphatic diol (c1) is 7 with respect to the total mass of the chain extender (C). The second molded body Ru der mass% or more, and,
A plating layer formed on a surface of the surface of the first molded body that is not covered with the second molded body is provided.

Furthermore, the method for producing a plated two-color molded body of the present invention includes a step of preparing a first molded body made of a hard resin having a Rockwell hardness of R80 or more,
Mainly organic diisocyanate (A) mainly composed of hexamethylene diisocyanate (a1), polymer polyol (B) mainly composed of polycarbonate diol (b1), and aliphatic diol (c1) having 2 to 10 carbon atoms. A chain extender (C) as a component, the content of the hexamethylene diisocyanate (a1) is 70% by mass or more based on the total mass of the organic diisocyanate (A), and the polycarbonate diol (b1 ) Is 70% by mass or more based on the total mass of the polymer polyol (B), the polymer polyol (B) has a number average molecular weight of 500 to 5,000, and the aliphatic diol (c1). contact of content chain extenders 70 mass% or more der Ru TPU with respect to the total weight of (C), at least a portion of said first molded body A step by state molding while maintaining, obtaining a second molded body said first molded body of at least a portion of is formed on the surface of plating two-color molding body made of the TPU was,
Forming a plating layer on the surface of the first molded body that is not covered with the second molded body by plating the two-color molded body for plating; and
It is the method characterized by including.

  ADVANTAGE OF THE INVENTION According to this invention, the color change by the plating process in the molded object which consists of soft resin is suppressed sufficiently, and the plating two-color molding thermoplastic which can obtain the plating two-color molded object which has sufficient plating process tolerance is obtained. It is possible to provide a polyurethane resin composition, a two-color molded article for plating, a two-color molded article with plating, and a method for producing them.

  Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.

  First, the plated two-color TPU of the present invention will be described. That is, the TPU for plating two-color molding of the present invention includes an organic diisocyanate (A) mainly composed of hexamethylene diisocyanate (a1), a polymer polyol (B) mainly composed of polycarbonate diol (b1), and It contains a chain extender (C) whose main component is an aliphatic diol (c1) having 2 to 10 carbon atoms.

  The organic diisocyanate (A) according to the present invention contains hexamethylene diisocyanate (hereinafter sometimes referred to as “HDI”) as a main component. In such an organic diisocyanate (A), the content of the hexamethylene diisocyanate (a1) is preferably 70% by mass or more and 80% by mass or more with respect to the total mass of the organic diisocyanate (A). It is more preferable that the content is 100% by mass. When the content of the hexamethylene diisocyanate (a1) is less than the lower limit, the weather resistance and plating treatment resistance tend to be insufficient.

  Examples of organic diisocyanates other than the hexamethylene diisocyanate (a1) that can be used in such organic diisocyanate (A) include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and xylene-1,4. -Diisocyanate, xylene-1,3-diisocyanate, tetramethylxylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, 2- Nitrodiphenyl-4,4′-diisocyanate, 2,2′-diphenylpropane-4,4′-diisocyanate, 3,3′-dimethyldiphenylmethane-4,4′-diisocyanate 4,4'-diphenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3'-dimethoxydiphenyl-4,4'-diisocyanate Aromatic diisocyanates such as tetramethylene diisocyanate, decamethylene diisocyanate, lysine diisocyanate; fats such as isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated tetramethylxylene diisocyanate A cyclic diisocyanate is mentioned.

  The polymer polyol (B) according to the present invention contains a polycarbonate diol (b1) described below as a main component. In such a polymer polyol (B), the content of the polycarbonate diol (b1) is preferably 70% by mass or more, more than 80% by mass with respect to the total mass of the polymer polyol (B). More preferably, it is particularly preferably 100% by mass. When the content of the polycarbonate diol (b1) is less than the lower limit, the water resistance, heat resistance, and plating treatment resistance tend to be insufficient.

  Moreover, in the TPU of the present invention, it is preferable that the blending amount of the polymer polyol (B) is such that the equivalent ratio of isocyanate groups to active hydrogen groups is within the range described later.

  The polycarbonate diol (b1) used in the present invention is generally obtained by a condensation reaction of a low molecular diol and a low molecular carbonate.

  Examples of the low molecular diol used to obtain such a polycarbonate diol (b1) include ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,2-butanediol, and 1,3-butane. Diol, 1,4-butanediol (hereinafter sometimes referred to as “1,4-BD”), 2-methyl-1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol (hereinafter, (Sometimes referred to as “1,6-HD”), 3-methyl-1,5-pentanediol (hereinafter sometimes referred to as “MPD”), neopentyl glycol, 1,8-octanediol, 1,9-nonanediol 3,3-dimethylol heptane, diethylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexane Sandimethanol, 2-ethyl-1,3-propanediol, 2-normalpropyl-1,3-propanediol, 2-isopropyl-1,3-propanediol, 2-normalbutyl-1,3-propanediol, 2 -Isobutyl-1,3-propanediol, 2-tertiarybutyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol 2-ethyl-2-normalpropyl-1,3-propanediol, 2-ethyl-2-normalbutyl-1,3-propanediol, 2-ethyl-3-ethyl-1,4-butanediol, 2- Methyl-3-ethyl-1,4-butanediol, 2,3-diethyl-1,5-pentanediol, 2,4-diethyl-1,5- Ntanjioru, 2,3,4-triethyl-1,5-pentanediol, dimethylol propionic acid, dimethylol butanoic acid, dimer acid diol, alkylene oxide adducts of bisphenol A and the like. Among these, an aliphatic low molecular diol having 2 to 10 carbon atoms is preferable, and MPD is more preferable from the viewpoint of transparency of the obtained molded body.

  Examples of the low molecular carbonate used to obtain such a polycarbonate diol (b1) include dialkyl carbonates such as dimethyl carbonate and diethyl carbonate; diaryl carbonates such as diphenyl carbonate; and alkylene carbonates such as ethylene carbonate and propylene carbonate. .

  The number average molecular weight of the polymer polyol (B) according to the present invention is not particularly limited, but is preferably 500 to 5000, and more preferably 1000 to 3000. When the number average molecular weight is less than the lower limit, the flexibility of the obtained TPU tends to be insufficient, and when the upper limit is exceeded, the mechanical strength of the obtained TPU tends to be insufficient and the moldability tends to decrease. .

  Furthermore, examples of polyols other than the polycarbonate diol (b1) that can be used in the polymer polyol (B) according to the present invention include polyester polyols, polyether polyols, polyether / ester polyols, and polyolefin polyols.

  The chain extender (C) according to the present invention is mainly composed of an aliphatic diol (c1) having 2 to 10 carbon atoms. In such a chain extender (C), the content of the aliphatic diol (c1) having 2 to 10 carbon atoms is 70% by mass or more based on the total mass of the chain extender (C). Preferably, it is 90 mass% or more, and it is especially preferable that it is 100 mass%. When the content of the aliphatic diol (c1) having 2 to 10 carbon atoms is less than the lower limit, the mechanical strength of the obtained TPU tends to be insufficient and the moldability tends to be lowered.

  In the TPU of the present invention, the molar ratio [(C) / (B)] of the chain extender (C) to the polymer polyol (B) is in the range of 0.5 to 5 (more preferably 1 to 3). If the molar ratio is less than the lower limit, the mechanical strength of the resulting TPU tends to be insufficient, while if it exceeds the upper limit, the moldability of the obtained TPU tends to be lowered.

  Examples of the aliphatic diol (c1) having 2 to 10 carbon atoms used in the present invention include ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,2-butanediol, and 1,3-butane. Diol, 1,4-BD, 2-methyl-1,3-propanediol, 1,5-pentanediol, 1,6-HD, MPD, neopentyl glycol, 1,8-octanediol, 1,9-nonane Diol, 3,3-dimethylol heptane, diethylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 2-ethyl-1,3-propanediol, 2-normalpropyl-1,3-propanediol, 2-isopropyl-1,3-propanediol, 2-normalbutyl-1,3-propanediol 2-isobutyl-1,3-propanediol, 2-tertiarybutyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, 2,2-diethyl-1,3-propane Diol, 2-ethyl-2-normalpropyl-1,3-propanediol, 2-ethyl-2-normalbutyl-1,3-propanediol, 2-ethyl-3-ethyl-1,4-butanediol, -Methyl-3-ethyl-1,4-butanediol, 2,3-diethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol. Among these, from the viewpoint of excellent mechanical strength and moldability of the obtained TPU, an aliphatic diol having 2 to 6 carbon atoms is preferable, and 1,4-BD is more preferable.

  Moreover, as chain extenders other than the said C2-C10 aliphatic diol (c1) which can be used for the chain extender (C) concerning this invention, for example, ethylenediamine, hexamethylenediamine, xylylenediamine, Examples include low molecular weight polyamines having a molecular weight of less than 500 (number average) such as isophoronediamine and ethylenetriamine; low molecular weight amino alcohols having a molecular weight of less than 500 (number average) such as monoethanolamine, diethanolamine and monopropanolamine.

  The TPU for plating two-color molding of the present invention contains the organic diisocyanate (A), the polymer polyol (B), and the chain extender (C). In addition, such TPU may contain other substances such as catalysts, foaming agents, antioxidants, ultraviolet absorbers, heat resistance improvers, antifoaming agents, leveling agents, colorants, inorganic and organic fillers as necessary. An agent, a lubricant, an antistatic agent, and a reinforcing material may be further contained.

  In the present invention, the equivalent ratio (NCO / OH) of isocyanate groups to active hydrogen groups (total amount of active hydrogen groups of the polymer polyol and the aliphatic diol) at the time of preparation for producing such TPU is 0. The range is preferably 85 / 1.00 to 1.00 / 1.00, and more preferably 0.90 / 1.00 to 0.99 / 1.00. If the equivalent ratio of isocyanate groups to active hydrogen groups is less than the above lower limit, the molecular weight of the resulting TPU is small, so the mechanical strength tends to be insufficient. On the other hand, if the upper limit is exceeded, the flexibility and molding of the obtained TPU Tend to decrease.

  Next, the two-color molded body for plating and the method for producing the same according to the present invention will be described. That is, the two-color molded body for plating of the present invention is formed on the first molded body made of a hard resin having a Rockwell hardness of R80 or more, and on at least a part of the surface of the first molded body. And a second molded body made of the TPU.

  The 1st molded object concerning this invention is a molded object which consists of hard resin. As the hard resin used in the present invention, a resin capable of forming a plating layer on the surface of the molded body can be appropriately used. For example, acrylonitrile butadiene styrene resin (ABS resin), polycarbonate resin (PC), polypropylene resin can be used. (PP), polyamide resin, polyacetal resin (POM), polyphenylene oxide resin (PPO). Among these hard resins, an ABS resin is particularly preferable from the viewpoint of adhesion with the TPU and ease of plating. In addition, it is preferable that the heat deformation temperature of such a hard resin is 80 degreeC or more.

  The Rockwell hardness of such a 1st molded object needs to be R80 or more, and it is especially preferable that it is R85 or more. If the Rockwell hardness is less than R80, the strength of the molded body is insufficient, and the hard feeling and operability of the molded body are impaired. Such Rockwell hardness can be measured using a Rockwell hardness meter by a method based on the method described in ASTM D785.

  The 2nd molded object concerning this invention consists of said TPU. In the two-color molded body for plating according to the present invention, the second molded body needs to be formed on at least a part of the surface of the first molded body. When the plating process described later is applied to the two-color molded body for plating according to the present invention, a plating layer is not formed on the second molded body, and the surface of the first molded body is the surface of the first molded body. The plating layer is formed only on the surface not covered with the second molded body. When the plating process is performed in this way, in the two-color molded body for plating according to the present invention, the second molded body has resistance to the plating process, and therefore the second layer in which no plating layer is formed. Discoloration due to the plating treatment in the molded body is sufficiently suppressed.

  The Shore A hardness of such a 2nd molded object is the range of 70-98 (preferably the range of 80-95) from a viewpoint of improving the cushioning property of the two-color molded object for plating obtained. Is preferred. Such Shore A hardness can be measured using a type A durometer (Shore A hardness meter) by a method based on the method described in ASTM D2240.

Moreover, the method for producing a two-color molded body for plating according to the present invention includes a step of preparing a first molded body made of the hard resin,
By molding the TPU while maintaining a state in contact with at least a part of the first molded body, the second molded body made of the TPU is formed on the surface of at least a part of the first molded body. And forming a two-color molded body for plating,
It is the method characterized by including.

  In the step of preparing the first molded body made of the hard resin, the first molded body is molded using the hard resin. As such a molding method, a known molding method can be appropriately employed, and is not particularly limited. For example, an injection molding method, a vacuum molding method, an extrusion molding method, a compression molding method, or a blow molding method may be employed. it can.

  In the step of obtaining the two-color molded body for plating, the second molded body made of the TPU is formed by molding the TPU while keeping the TPU in contact with at least a part of the first molded body. A two-color molded body for plating is obtained by forming on at least a part of the surface of the first molded body. In such a process, the second molded body made of TPU is molded, and the second molded body is bonded to the first molded body (for example, heat-sealed), whereby the first molded body and the first molded body are bonded. A two-color molded article for plating provided with the two molded articles can be obtained. As a method of molding the second molded body and heat-sealing the first molded body in this way, for example, (i) using two cylinders, injection molding with a hard resin as the first molded body After that, a space is formed in the mold, and then the TPU is injection-molded in the space, the so-called two-color injection molding method, (ii) the first molded body made of the hard resin molded by injection molding or the like is previously molded A method of so-called insert molding in which TPU is injection molded in this mold, and (iii) TPU is extruded from the first molded body made of the hard resin formed by injection molding or the like. (Iv) A method of compression-molding TPU can be adopted for the first molded body made of the hard resin molded by injection molding or the like. Among these methods, the two-color injection molding method is preferable from the viewpoint of adhesion between the hard resin and the TPU.

  Next, the plated two-color molded body of the present invention and the manufacturing method thereof will be described. That is, the plated two-color molded body of the present invention is not covered with the second molded body among the first molded body, the second molded body, and the surface of the first molded body. A plating layer formed on the surface is provided. Such a two-color molded body with plating can be obtained by plating the two-color molded body for plating according to the present invention.

  Although it does not specifically limit as a metal used for such a plating layer, For example, chromium, tin, zinc, copper, nickel, cobalt, magnesium, silver, gold | metal | money is mentioned. Moreover, the thickness of such a plating layer is not particularly limited, but is preferably in the range of 0.1 to 50 μm.

Moreover, the method for producing a two-color molded body with plating according to the present invention includes the step of obtaining the two-color molded body for plating according to the present invention,
Forming a plating layer on the surface of the first molded body that is not covered with the second molded body by plating the two-color molded body for plating; and
It is a method including.

  In the method for producing a two-color molded article with plating according to the present invention, first, the two-color molded article for plating according to the present invention is obtained by the method for producing a two-color molded article for plating according to the present invention.

  In the step of forming a plating layer on the surface of the first molded body that is not covered with the second molded body, the two-color molded body for plating is plated. As a method of such plating treatment, a publicly known method can be adopted as appropriate and is not particularly limited. For example, the method described below can be adopted. That is, as a plating method, a method including a degreasing process, an etching process, a neutralization process, a catalyst process, an accelerator process, an electroless nickel plating process, and an electrolytic plating process is adopted. Can do. In addition, in such a method, it is desirable to put a water washing process between each process.

  Further, in such a plating method, an aqueous solution containing chromic anhydride or sulfuric acid in the etching step, a mixed solution containing nickel sulfate or sodium diphosphite in the electroless nickel plating step, sulfuric acid in the electrolytic plating step Various plating treatment solutions such as a mixed solution containing copper or sulfuric acid are used. However, in the method for producing a two-color molded body with plating according to the present invention, since the second molded body has resistance to the plating process, the discoloration due to the plating process in the second molded body in which no plating layer is formed. Is sufficiently suppressed.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example. Unless otherwise specified, “part” and “%” in the text are based on mass. Moreover, the raw material used in the Example and the comparative example is as follows.

(Raw material)
<Isocyanate>
HDI: Hexamethylene diisocyanate, manufactured by Nippon Polyurethane Industry Co., Ltd., trade name “HDI”.
MDI: 4,4′-diphenylmethane diisocyanate, manufactured by Nippon Polyurethane Industry Co., Ltd., trade name “Millionate MT”.

<Polymer polyol>
Polyol A: polyester polyol obtained from 1,4-butanediol and adipic acid, number average molecular weight 1000.
Polyol B: Polytetramethylene glycol, number average molecular weight 1000, manufactured by Hodogaya Chemical Co., Ltd., trade name “PTG-1000SN”.
Polyol C: Polycarbonate diol obtained from 1,6-hexanediol and diethyl carbonate, number average molecular weight 1000.
Polyol D: Polycarbonate diol obtained from 3-methyl-1,5-pentanediol and diethyl carbonate, number average molecular weight 1000.

<Chain extender>
1,4-BD: 1,4-butanediol, manufactured by Mitsubishi Chemical Corporation.

<Catalyst>
DOTDL: Dioctyltin dilaurate, manufactured by Kishida Chemical Co., Ltd.

(Examples 1 and 2 and Comparative Examples 1 to 3)
<Preparation of Thermoplastic Polyurethane Resin Composition for Plated Two-Color Molding>
In Example 1, a thermoplastic polyurethane resin composition was obtained as follows. Specifically, 857.3 parts of polyol D and 142.7 parts of 1,4-BD were charged into a mixing tank and then mixed to obtain a polyol premix. Thereafter, the temperature of the obtained polyol premix was adjusted to 75 ° C. On the other hand, after charging HDI into another mixing tank, the temperature was adjusted to 50 ° C.

  Next, the polyol premix and HDI were put into a twin screw extruder (manufactured by Ikegai Co., Ltd.). The temperatures in the vicinity of the hopper, the middle part and the tip part in the twin-screw extruder were adjusted to 160 ° C., 180 ° C. and 200 ° C., respectively. Then, these raw materials are continuously fed from the hopper port of the twin screw extruder under the conditions that the amount of polyol premix is 2139 g / min and the amount of HDI is 861 g / min. After discharging and cooling, it cut | disconnected to the pellet form and obtained the pellet-shaped thermoplastic polyurethane resin composition (PU-1). In addition, the equivalent ratio (NCO / OH) of the isocyanate group with respect to the active hydrogen group in the obtained thermoplastic polyurethane resin composition was 0.98.

  In Example 2, a pellet-shaped thermoplastic polyurethane resin composition (PU) was prepared in the same manner as in Example 1 except that the composition of the polyol premix and the production conditions of the composition were changed as shown in Table 1, respectively. -2) was obtained. Further, in Comparative Examples 1 to 3, a pellet-shaped thermoplastic polyurethane resin composition in the same manner as in Example 1 except that the composition of the polyol premix and the production conditions of the composition were changed as shown in Table 1, respectively. (PU-3) to (PU-5) were obtained.

<Preparation of two-color molded body for plating>
In Example 1, a two-color molded body for plating was obtained as follows. That is, first, using a two-color molding injection molding machine (manufactured by Nissei Plastic Industry Co., Ltd., product name “DC-120-9A”), ABS resin (manufactured by UMG ABS Co., Ltd., trade name “Psyco Lac 3001M”) is used. Two colors for plating are formed by injection molding as a first molded body and then integrally forming the obtained thermoplastic polyurethane resin composition (PU-1) by injection molding inside the first molded body. A molded body (size: 15 mm × 8 mm × 5 mm) was obtained. The two-color molded article for plating thus obtained is shown in FIG. That is, the two-color molded body 10 for plating shown in FIG. 1 includes a first molded body 1 and a second molded body 2 molded inside the first molded body 1.

  Further, in Example 2, two colors for plating were used in the same manner as in Example 1 except that the thermoplastic polyurethane resin composition (PU-2) was used instead of the thermoplastic polyurethane resin composition (PU-1). A molded body was obtained. Furthermore, in Comparative Examples 1 to 3, Example 1 was used except that the thermoplastic polyurethane resin compositions (PU-3) to (PU-5) were used instead of the thermoplastic polyurethane resin composition (PU-1), respectively. In the same manner as above, a two-color molded article for plating was obtained.

<Production and evaluation of two-color molded body with plating>
(I) Production of two-color molded body with plating The two-color molded body for plating obtained in Examples 1 and 2 and Comparative Examples 1 to 3 was subjected to the following plating treatment, and the two-color molded body with plating. Got. That is, for the obtained two-color molded article for plating, degreasing treatment, etching treatment, neutralization treatment, catalyst treatment, accelerator treatment, electroless nickel plating treatment, Electrolytic plating treatment was performed. In such plating treatment, a water washing step was performed between the steps.

  In the degreasing treatment, the two-color molded article for plating of the present invention is heated to a mixed solution (solvent or dispersion medium: water) containing 20 g / L of sodium sulfate, 20 g / L of sodium phosphate and 2 g / L of a surfactant. It was immersed for 5 minutes at 50 ° C.

  In the etching treatment, the two-color molded body after degreasing was immersed in an aqueous solution containing 400 g / L of chromic anhydride and 400 g / L of sulfuric acid at a temperature of 68 ° C. for 10 minutes.

  In the neutralization treatment, the etched two-color molded article was immersed in a 12 mol / L concentrated hydrochloric acid aqueous solution at room temperature (25 ° C.) for 1 minute.

  In the catalyst treatment, the neutralized dichroic molded product is placed in an aqueous solution containing 0.2 g / L of palladium chloride, 15 g / L of stannous chloride and 150 mL / L of hydrochloric acid at room temperature (25 ° C.) for 1 minute. By soaking, palladium was adsorbed on the surface of the two-color molded body.

  In the accelerator treatment, the two-color molded body after the catalyst process is immersed in an aqueous solution containing 100 g / L of sulfuric acid at a temperature of 40 ° C. for 4 minutes, so that the tin adsorbed with palladium is two-color molded body. Removed from.

  In the electroless nickel plating treatment, first, the pH of a mixed solution (solvent or dispersion medium: water) containing 30 g / L of nickel sulfate, 20 g / L of sodium diphosphite and 50 g / L of sodium citrate is set to 9.0. Adjusted. Next, an electroless nickel plating layer is formed on the two-color molded body by immersing the two-color molded body after the accelerator process in the mixed liquid in the mixed liquid after pH adjustment at a temperature of 35 ° C. for 10 minutes. I let you.

In the electroplating treatment, first, the two-color molded body after electroless nickel plating is subjected to a temperature of 25 ° C. and a current density in a plating bath containing 200 g / L of copper sulfate, 50 g / L of sulfuric acid and an appropriate amount of brightener. Electrolytic copper plating was performed under the condition of 3 A / dm ² . Next, with respect to the two-color molded body after electrolytic copper plating, in a plating bath containing 250 g / L of nickel sulfate, 40 g / L of nickel chloride and 30 g / L of boric acid, the temperature is 55 ° C. and the current density is 3 A / dm ^2. Electrolytic nickel plating was performed under the conditions described above. Next, electrolytic chrome was plated on the two-color molded body after electrolytic nickel plating in a plating bath containing 250 g / L of chromic acid and 2.5 g / L of sulfuric acid at a temperature of 45 ° C. and a current density of 20 A / dm ^2. Plating was performed.

(II) Evaluation of two-color molded body with plating About the two-color molded body with plating obtained in Examples 1 and 2 and Comparative Examples 1 to 3, discoloration of the second molded body, resistance to plating treatment and Transparency was evaluated. The obtained results are shown in Table 2.

(I) Evaluation method of discoloration The YI (yellowness) of the second molded body in the two-color molded body for plating before the plating treatment and the two-color molded body with plating after the plating treatment is measured by a spectrocolorimeter (Suga Test Instruments Co. The difference ΔYI (YI _a −YI _b ) between the YI value (YI _a ) of the second molded body after the plating treatment and the YI value (YI _b ) of the second molded body before the plating treatment. ) Was calculated. The case where the value of ΔYI was less than 5 was determined as “◯”, and the case where the value of ΔYI was 5 or more was determined as “x”.

(Ii) Evaluation method of plating treatment resistance The plating treatment is performed by visually observing the surfaces of the second molded body in the two-color molded body for plating before the plating process and the two-color molded body with plating after the plating process. Resistance was evaluated. In addition, evaluation of plating processing tolerance was determined based on the following reference | standard.
○: No difference in surface appearance before and after plating treatment.
Δ: The surface of the second molded body after the plating treatment is slightly rough, and the surface of the second molded body after the plating treatment is rougher when compared before and after the plating treatment.
X: The surface of the 2nd molded object after a plating process is rough.

(Iii) Method for evaluating transparency The transparency was evaluated by visually observing the second molded body in the two-color molded body with plating after the plating treatment. When the second molded body was cloudy and bloom or bleed was found, it was judged as “Δ”, and when cloudy, bloom and bleed were not seen at all, it was judged as “◯”.

  As is apparent from the results shown in Table 2, when the plated two-color thermoplastic polyurethane resin composition for molding (Examples 1 and 2) of the present invention is used, the second molded body made of a soft resin is used. It was confirmed that discoloration due to the plating treatment was sufficiently suppressed, and a two-color molded article for plating having sufficient plating treatment resistance was obtained. Further, when a thermoplastic polyurethane resin composition containing a polycarbonate diol obtained from 3-methyl-1,5-pentanediol and diethyl carbonate was used (Example 1), two plated plates having excellent transparency were used. It was confirmed that a color molded body was obtained.

  As described above, according to the present invention, the discoloration due to the plating process in the molded body made of the soft resin is sufficiently suppressed, and the plated two-color molded body having sufficient resistance to the plating process can be obtained. It becomes possible to provide a thermoplastic polyurethane resin composition for two-color molding, a two-color molded body for plating, a two-color molded body with plating, and a method for producing them.

It is a schematic cross section which shows the two-color molded object for plating obtained in the Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... 1st molded object, 2 ... 2nd molded object, 10 ... Two-color molded object for plating.

Claims (5)

Two-color molding with plating used for the second molded body of the two-color molded body for plating provided with a first molded body made of a hard resin having a Rockwell hardness of R80 or more and a second molded body made of a soft resin. A thermoplastic polyurethane resin composition for use,
And f Kisa organic diisocyanate mainly comprising diisocyanate (a1) (A), a polymer polyol (B) mainly composed of a polycarbonate diol (b1), the aliphatic diol having 2 to 10 carbon atoms (c1) Containing a chain extender (C) as a main component ,
Content of the said hexamethylene diisocyanate (a1) is 70 mass% or more with respect to the total mass of organic diisocyanate (A),
The content of the polycarbonate diol (b1) is 70% by mass or more based on the total mass of the polymer polyol (B),
The number average molecular weight of the polymer polyol (B) is 500 to 5,000,
The content of the aliphatic diol (c1) is 70% by mass or more based on the total mass of the chain extender (C).
For two-color with plating molding, wherein the this thermoplastic polyurethane resin composition. A first molded body made of a hard resin having a Rockwell hardness of R80 or more, and
A polymer polyol formed on at least a part of the surface of the first molded body, the organic diisocyanate (A) containing hexamethylene diisocyanate (a1) as a main component and the polycarbonate diol (b1) as a main component. (B), and Ri Do a thermoplastic polyurethane resin composition containing a chain extender mainly composed of an aliphatic diol having 2 to 10 carbon atoms (c1) (C), the hexamethylene diisocyanate (a1) The content is 70% by mass or more with respect to the total mass of the organic diisocyanate (A), the content of the polycarbonate diol (b1) is 70% by mass or more with respect to the total mass of the polymer polyol (B), The polymer polyol (B) has a number average molecular weight of 500 to 5,000, and the aliphatic diol (c1) content is a chain extender. Two-color molded article for plating, characterized in that it comprises a second molded body Ru der least 70% by weight relative to the total weight of C). Preparing a first molded body made of a hard resin having a Rockwell hardness of R80 or higher;
Mainly organic diisocyanate (A) mainly composed of hexamethylene diisocyanate (a1), polymer polyol (B) mainly composed of polycarbonate diol (b1), and aliphatic diol (c1) having 2 to 10 carbon atoms. A chain extender (C) as a component, the content of the hexamethylene diisocyanate (a1) is 70% by mass or more based on the total mass of the organic diisocyanate (A), and the polycarbonate diol (b1 ) Is 70% by mass or more based on the total mass of the polymer polyol (B), the polymer polyol (B) has a number average molecular weight of 500 to 5,000, and the aliphatic diol (c1). the content of chain extender to total weight thermoplastic polyurethane resin composition Ru der to 70 wt% with respect to the (C), said first molded body A second molded body made of the thermoplastic polyurethane resin composition is formed on at least a part of the surface of the first molded body by molding while maintaining at least a part in contact with the plating. Obtaining a two-color molded body;
The manufacturing method of the two-color molded object for plating characterized by including. A first molded body made of a hard resin having a Rockwell hardness of R80 or higher,
A polymer polyol formed on at least a part of the surface of the first molded body, the organic diisocyanate (A) containing hexamethylene diisocyanate (a1) as a main component and the polycarbonate diol (b1) as a main component. (B), and Ri Do a thermoplastic polyurethane resin composition containing a chain extender mainly composed of an aliphatic diol having 2 to 10 carbon atoms (c1) (C), the hexamethylene diisocyanate (a1) The content is 70% by mass or more with respect to the total mass of the organic diisocyanate (A), the content of the polycarbonate diol (b1) is 70% by mass or more with respect to the total mass of the polymer polyol (B), The polymer polyol (B) has a number average molecular weight of 500 to 5,000, and the aliphatic diol (c1) content is a chain extender. The second molded body Ru der least 70% by weight relative to the total weight of C), and,
A plated two-color molded body comprising a plated layer formed on a surface of the first molded body that is not covered with the second molded body. Preparing a first molded body made of a hard resin having a Rockwell hardness of R80 or higher;
Mainly organic diisocyanate (A) mainly composed of hexamethylene diisocyanate (a1), polymer polyol (B) mainly composed of polycarbonate diol (b1), and aliphatic diol (c1) having 2 to 10 carbon atoms. A chain extender (C) as a component, the content of the hexamethylene diisocyanate (a1) is 70% by mass or more based on the total mass of the organic diisocyanate (A), and the polycarbonate diol (b1 ) Is 70% by mass or more based on the total mass of the polymer polyol (B), the polymer polyol (B) has a number average molecular weight of 500 to 5,000, and the aliphatic diol (c1). the content of chain extender to total weight thermoplastic polyurethane resin composition Ru der to 70 wt% with respect to the (C), said first molded body A second molded body made of the thermoplastic polyurethane resin composition is formed on at least a part of the surface of the first molded body by molding while maintaining at least a part in contact with the plating. Obtaining a two-color molded body;
Forming a plating layer on the surface of the first molded body that is not covered with the second molded body by plating the two-color molded body for plating; and
The manufacturing method of the two-color molded object with a plating characterized by including.

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