JP6085466B2 - Method for producing flame-retardant resin molded product - Google Patents

Description

  The present invention relates to a method for producing a flame-retardant resin molded product, and more specifically to a method for producing a thin-walled flame-retardant resin molded product using polybutylene terephthalate or the like as a resin component.

  Polybutylene terephthalate resin (hereinafter also referred to as “PBT resin”) has a high thermal deformation temperature and is excellent in electrical characteristics, mechanical characteristics, weather resistance, water resistance, chemical resistance, etc. It is used for various applications such as parts. And in such a use, a flame retardance is an important performance, and various examination is made in order to give a PBT resin a flame retardance. In particular, for electrical and electronic parts, flame retardant compositions that achieve V-0 as flame retardance based on the UL94 combustion test have been conventionally studied (for example, see Patent Documents 1 and 2).

  Among the electrical and electronic parts, the housing, cover, chassis, etc. are thin, so not only the flame retardancy of V-0, but also 5VA (particularly flat plate hole: burn) Through) is also required. That is, burn-through resistance is required for the above applications. Therefore, conventionally, it has been necessary to add a large amount of flame retardant or increase the thickness within a limited range in order to achieve 5 VA flame retardancy. However, when a large amount of a flame retardant is added, there is a problem that the mechanical properties are easily lowered even though the flame retardancy can be improved. Further, when the wall thickness is increased, there are problems that the degree of freedom in design such as shape interference with other parts is reduced and the weight of the product is increased.

  On the other hand, in a non-reinforced composition that does not include a reinforcing filler, burn-through is likely to occur due to the influence of orientation and strain generated during injection molding. Therefore, in order to reduce the orientation and strain during injection molding, it is conceivable to increase the mold temperature, decrease the injection speed, etc., but this is not always sufficient. In particular, when the composition contains an elastomer, it becomes more difficult to impart flame retardancy.

JP 2012-25931 A JP 2009-149780 A

  The present invention has been made in view of the above-described conventional problems, and enables the production of a flame-retardant resin molded product satisfying 5VA in the UL94 flammability standard while suppressing the use of a flame retardant and being thin. It is an object to provide a method for producing a flame-retardant resin molded product.

The present invention has been found that excellent burn-through resistance can be obtained in a thin-walled flame-retardant resin molded product by heating and press-molding without adding a large amount of flame retardant.
The present invention for solving the above problems is as follows.
(1) A method for producing a flame-retardant resin molded product having a flame retardance of 5 VA at a thickness of 1.5 mm according to UL94 combustion test,
A method for producing a flame-retardant resin molded article, comprising a step of heating and pressurizing a composition containing a thermoplastic resin and a flame retardant component.

(2) The method for producing a flame-retardant resin molded product according to (1), wherein the step of molding by heating and pressing is a step other than both injection molding and extrusion molding.

(3) Production of the flame-retardant resin molded product according to (1) or (2), wherein the composition before heating and pressing is any of powder, granule, injection-molded product, and extruded product. Method.

(4) The method for producing a flame-retardant resin molded article according to any one of (1) to (3), wherein the thermoplastic resin is a polybutylene terephthalate resin.

(5) The method for producing a flame-retardant resin molded article according to any one of (1) to (4), wherein the composition does not contain a fibrous inorganic filler.

(6) The method for producing a flame-retardant resin molded article according to any one of (1) to (5), wherein the composition further contains an elastomer.

(7) The method for producing a flame-retardant resin molded article according to any one of (1) to (6), wherein the flame-retardant resin molded article is an electric and electronic member including a thick portion of 1.5 mm or more.

(8) The method for producing a flame-retardant resin molded product according to (7), wherein the electric and electronic member is a housing, a cover, or a chassis.

  According to the present invention, there is provided a method for producing a flame-retardant resin molded product that enables production of a flame-retardant resin molded product that satisfies the 5 VA in the UL94 flammability standard while suppressing the use of a flame retardant. can do.

The method for producing a flame-retardant resin molded article of the present invention is a method for producing a flame-retardant resin molded article having a flame retardance of 5 VA at a thickness of 1.5 mm in accordance with UL94 combustion test, It includes a step of forming a composition containing a flame retardant by heating and pressing.
Below, each component of the composition used for the manufacturing method of this invention is demonstrated first.

[Thermoplastic resin]
Examples of the thermoplastic resin include resins that can be used for applications requiring 5 VA as flame retardancy in accordance with the UL94 combustion test. Examples thereof include polyester resins such as PBT resin and polyethylene terephthalate resin, polycarbonate resins, and polyphenylene ethers. Resin, polyamide resin, polyolefin resin, polyphenylene sulfide resin, liquid crystal polymer, polystyrene resin, styrene-based copolymer such as acrylonitrile-butadiene-styrene copolymer, etc. Preferably used. Below, PBT resin is demonstrated.

(PBT resin)
The polybutylene terephthalate resin (PBT) is composed of a dicarboxylic acid component containing at least terephthalic acid or an ester-forming derivative thereof (C _1-6 alkyl ester, acid halide, etc.), and an alkylene glycol (1, 4 carbon atoms). 4-butanediol) or a resin obtained by polycondensation with a glycol component containing an ester-forming derivative thereof (acetylated product or the like). The polybutylene resin is not limited to homopolybutylene terephthalate, but may be a copolymer containing 60 mol% or more (particularly 75 mol% or more and 95 mol% or less) of butylene terephthalate units.

  The amount of terminal carboxyl groups of the polybutylene terephthalate resin is not particularly limited as long as the effects of the present invention are not impaired. The amount of terminal carboxyl groups of the polybutylene terephthalate resin is preferably 30 meq / kg or less, and more preferably 25 meq / kg or less.

  The intrinsic viscosity (IV) of the polybutylene terephthalate resin is not particularly limited as long as the effects of the present invention are not impaired. The intrinsic viscosity of the polybutylene terephthalate resin is preferably 0.60 to 1.20 dL / g. From the viewpoint of preventing cracking and improving toughness for improving heating and cooling durability, it is more preferably 0.65 to 1.15 dL / g. When a polybutylene terephthalate resin having an intrinsic viscosity in such a range is used, the resulting polybutylene terephthalate resin composition has particularly excellent moldability. The intrinsic viscosity can also be adjusted by blending polybutylene terephthalate resins having different intrinsic viscosities. For example, a polybutylene terephthalate resin having an intrinsic viscosity of 0.9 dL / g is prepared by blending a polybutylene terephthalate resin having an intrinsic viscosity of 1.0 dL / g and a polybutylene terephthalate resin having an intrinsic viscosity of 0.8 dL / g. Can do. The intrinsic viscosity (IV) of the polybutylene terephthalate resin can be measured, for example, in o-chlorophenol at a temperature of 35 ° C.

In the polybutylene terephthalate resin, examples of dicarboxylic acid components (comonomer components) other than terephthalic acid and its ester-forming derivatives include, for example, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4′-dicarboxydiphenyl ether. C _8-14 aromatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid and the like C _4-16 alkanedicarboxylic acids; cyclohexanedicarboxylic acid and the like C _5-10 cycloalkanedicarboxylic acids; And an ester-forming derivative of a dicarboxylic acid component (C _1-6 alkyl ester derivative, acid halide, etc.). These dicarboxylic acid components can be used alone or in combination of two or more.

Among these dicarboxylic acid components, C _8-12 aromatic dicarboxylic acids such as isophthalic acid, and C _6-12 alkanedicarboxylic acids such as adipic acid, azelaic acid, and sebacic acid are more preferable.

In the polybutylene terephthalate resin, as a glycol component (comonomer component) other than 1,4-butanediol, for example, ethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, hexamethylene glycol, neopentyl glycol, C _2-10 alkylene glycol such as 1,3-octanediol; polyoxyalkylene glycol such as diethylene glycol, triethylene glycol and dipropylene glycol; alicyclic diol such as cyclohexanedimethanol and hydrogenated bisphenol A; bisphenol A, Aromatic diols such as 4,4'-dihydroxybiphenyl; 2 mol addition of bisphenol A ethylene oxide, 3 mol addition of bisphenol A propylene oxide Etc., an alkylene oxide adduct of C _2-4 of bisphenol A; or ester-forming derivatives of these glycols (acetylated, etc.). These glycol components can be used alone or in combination of two or more.

Among these glycol components, C _2-6 alkylene glycol such as ethylene glycol and trimethylene glycol, polyoxyalkylene glycol such as diethylene glycol, and alicyclic diol such as cyclohexanedimethanol are more preferable.

Examples of comonomer components that can be used in addition to the dicarboxylic acid component and the glycol component include 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, and 4-carboxy-4′-hydroxybiphenyl. Aromatic hydroxycarboxylic acids; Aliphatic hydroxycarboxylic acids such as glycolic acid and hydroxycaproic acid; C _3-12 lactones such as propiolactone, butyrolactone, valerolactone, caprolactone (ε-caprolactone, etc.); esters of these comonomer components And forming derivatives (C _1-6 alkyl ester derivatives, acid halides, acetylated compounds, etc.).

[Flame retardant component]
As a flame retardant component, there are a case where a flame retardant is used alone and a case where a flame retardant and a flame retardant aid are used in combination.
The flame retardant is used for imparting flame retardancy to the flame retardant resin molded product of the present invention. Specific examples of the flame retardant include halogen-based flame retardants such as brominated flame retardants, phosphorus-based flame retardants, nitrogen-based flame retardants, and silicone-based flame retardants, among which brominated flame retardants and phosphorus-based flame retardants are preferred. .
Specific examples of the flame retardant aid include antimony compounds such as antimony trioxide and nitrogen-containing compounds such as triazine, which are selected according to the flame retardant used.
In the flame-retardant resin molded article of the present invention, the flame retardant is contained in an amount of 10 to 40 parts by mass, preferably 15 to 30 parts by mass with respect to 100 parts by mass of the thermoplastic resin. Further, the flame retardant aid is contained in an amount of 4 to 15 parts by mass, preferably 5 to 10 parts by mass with respect to 100 parts by mass of the thermoplastic resin.

[Elastomer]
Elastomers are used to improve impact resistance. Examples include olefin elastomers, vinyl chloride elastomers, styrene elastomers, polyester elastomers, butadiene elastomers, urethane elastomers, polyamide elastomers, and silicone elastomers. Specifically, ethylene ethyl acrylate (EEA), methacrylic acid ester / butylene / styrene (MBS), ethylene glycidyl methacrylate (EGMA), polytetramethylene glycol (PTMG) polyester elastomer, and the like can be used.
In the flame-retardant resin molded article of the present invention, the elastomer is contained in an amount of 10 to 30 parts by mass, preferably 10 to 20 parts by mass, with respect to 100 parts by mass of the thermoplastic resin. By containing 10 parts by mass or more of the elastomer, the impact resistance improvement effect is sufficiently exhibited, and by making the elastomer 30 parts by mass or less, an extremely low flame retardancy can be suppressed.

[Other ingredients]
The composition may contain other components as necessary. Other ingredients include anti-dripping agents, antioxidants such as hindered phenols, phosphorus-based secondary antioxidants, thioether-based secondary antioxidants, inorganic crystal nucleating agents, mold release agents, and coloring agents. Can be contained.
In the present invention, non-reinforced moldings are targeted, and reinforcing fillers such as inorganic fillers are not used.

In the method for producing a flame-retardant resin molded article of the present invention, the above composition is used and molded by heating and pressing. That is, the manufacturing method of the present invention is a molding technique including steps other than both injection molding and extrusion molding, and the molding technique suppresses the orientation and strain of the resin in the molded product and reduces the occurrence of burn-through. be able to. Examples of the molding technique include press molding, which can be performed using equipment and devices in press molding.
The heating temperature is preferably 150 to 280 ° C, more preferably 200 to 270 ° C, and further preferably 240 to 260 ° C.
The applied pressure is preferably 0.0 to 10.0 MPa, more preferably 0.5 to 5.0 MPa, still more preferably 1.0 to 3.0 MPa. It is particularly preferable that the pressure be 0 to 1.5 MPa. The heating and pressing time is preferably 1 to 120 minutes, more preferably 3 to 60 minutes, further preferably 5 to 30 minutes, and particularly preferably 6 to 15 minutes.
Note that when the heating and pressing time is sufficiently long, the heating temperature and the pressing force can be lowered. In particular, when the heating and pressing time is 15 min or longer (for example, 30 min), the pressing force may be zero. . Furthermore, when the heating and pressing time is 30 min or longer (for example, 60 min), the heating temperature may be equal to or lower than the melting point of the resin.

  In the present invention, the composition is heated and pressurized as described above, and the form of the composition used for heating and pressing is any one of powder, granules, injection-molded products, and extruded products. It is preferable. That is, in the present invention, the composition may be heated and pressed as it is, or may be heated and pressed after injection molding and extrusion molding.

As a flame-retardant resin molded product obtained by the production method of the present invention, for example, the molded product can be an electric and electronic member including a thick portion having a thickness of 1.5 mm or more. That is, the flame-retardant resin molded product according to the present invention is a molded product having a thin portion of 1.5 mm because the flame retardancy according to the UL94 combustion test has 5 VA at a thickness of 1.5 mm. Reduces the occurrence of burn-through.
Specific examples of such a flame-retardant resin molded product include a housing, a cover, and a chassis.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

[Examples 1 to 4, Comparative Examples 1 to 7]
In each of the examples and comparative examples, PBT resin, elastomer, flame retardant, flame retardant aid, and PTFE (polytetrafluoroethylene) are blended in the number of parts (parts by mass) shown in Table 1 below and have a 32 mmφ screw. The mixture was melt-kneaded at 260 ° C. with a twin-screw extruder (manufactured by Nippon Steel Works) to obtain a pellet-like flame-retardant resin composition.
In addition, the detail of said each component is as follows.
PBT resin: manufactured by Wintech Polymer Co., Ltd., DURANEX (registered trademark) (intrinsic viscosity: 0.88 dL / g)
Elastomer: manufactured by Rohm and Haas Japan, Paraloid EXL2314
Flame retardant: FR1025 manufactured by ICLP Japan Co., Ltd.
Flame retardant aid: NIPPON SEIKO CO., LTD., PATOX-M
PTFE: Asahi Glass Co., Ltd., Fullon CD-076

The obtained pellets were molded as follows in each Example and Comparative Example.
(1) Examples 1 and 2
The obtained pellets were used as they were and heated and pressurized under the conditions shown in Table 1 to obtain flame retardant resin molded products of Examples 1 and 2.
(2) Examples 3 and 4
First, the obtained pellet was injection molded under the conditions shown in Table 1 to obtain a pre-molded product. Furthermore, this pre-molded product was heated and pressurized under the conditions shown in Table 1 to obtain flame-retardant resin molded products of Examples 3 and 4.
(3) Comparative Examples 1-7
The obtained pellets were injection molded under the conditions shown in Table 1 to obtain flame retardant resin molded products of Comparative Examples 1-7.
In addition, the heat pressurization in Examples 1-4 was performed using Mini Test Press MP-SNH (made by Toyo Seisakusho Co., Ltd.).

The obtained flame-retardant resin molded product was evaluated for flame retardancy as follows.
(A) In accordance with the method of Subject 94 (UL94) of Underwriters Laboratories, flammability was tested using five test pieces (thickness 1.5 mm) and evaluated according to the evaluation method described in UL94. In Table 1, the case where V-0 is satisfied is indicated by ◯, and the case where V-0 is not satisfied is indicated by ×.
(B) In accordance with the method of Underwriters Laboratories Subject 94 (UL94), five strip test pieces (thickness 3 mm) were tested for flammability, and three more flat test pieces ( Using a thickness of 3 mm), a test for piercing during combustion was performed, and evaluation was performed according to the evaluation method described in UL94. Similarly, a test of flammability using 5 strip test pieces (thickness 1.5 mm) and a test for puncturing during combustion using 3 flat test pieces (thickness 1.5 mm). Performed and evaluated similarly. In Table 1, the case where 5 VA is satisfied is indicated by ◯, and the case where it is not satisfied is indicated by ×.

From Table 1, in Examples 1-4, the molded product which satisfy | fills 5VA with respect to the flat plate of thickness 1.5mm was obtained especially as flame retardance based on UL94 combustion test. In particular, in Example 4, it can be seen that the flame retardancy of 5 VA was obtained even when the pressure was 0.
On the other hand, in Comparative Examples 1-7, even if the injection conditions were changed or the amount of flame retardant added was increased, none of the 5VA flame retardancy was obtained.

Claims (6)

A method for producing a flame-retardant resin molded product having a flame retardance of 5 VA at a thickness of 1.5 mm according to a UL94 combustion test,
Including a step of molding by heating and pressurizing a composition containing a thermoplastic resin, a flame retardant component, and an elastomer at a heating temperature of 150 ° C. to 280 ° C. and a pressure of 0.0 MPa to 10.0 MPa ,
The composition before heating and pressing is any of powder, granule, injection molded product, and extrusion molded product,
The step of forming by heating and pressing is a step other than both injection molding and extrusion molding,
The composition does not include a fibrous inorganic filler;
A method for producing a flame-retardant resin molded product. The method for producing a flame-retardant resin molded article according to claim 1, wherein the step of molding by heating and pressing is a step of performing press molding .   The method for producing a flame-retardant resin molded article according to claim 1 or 2, wherein the thermoplastic resin is a polybutylene terephthalate resin. The method for producing a flame-retardant resin molded article according to any one of claims 1 to 3, wherein the flame retardant component contains a halogen-based flame retardant.   The method for producing a flame-retardant resin molded product according to any one of claims 1 to 4, wherein the flame-retardant resin molded product is an electric and electronic member including a thick portion having a thickness of 1.5 mm or more.   The method for producing a flame-retardant resin molded product according to claim 5, wherein the electric and electronic member is a housing, a cover, or a chassis.