JPS5812302B2 - Nannenseiseikeihinnoseizouhouhou - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing flame-retardant molded products.

Specifically, the present invention relates to a method for manufacturing polybutylene terephthalate resin molded products that have a beautiful appearance and excellent flame retardancy.

Polybutylene terephthalate resin (hereinafter referred to as PBT)
Due to its excellent physical properties and processability, it is used in many applications, especially gears, pulleys,
It is widely used in the field of so-called engineering plastics such as electrical parts.

Engineering plastics are naturally required to be flame retardant due to their uses, but PBT, like other thermoplastic resins, does not have sufficient flame retardancy, so there was an urgent need to develop an excellent flame retardant.

Various proposals have been made to date, but among them, a combination of a halogen-containing aromatic organic compound and antimony trioxide is the most excellent flame retardant in terms of flame retardancy.

However, the halogen-containing aromatic organic compounds conventionally used are still not fully satisfactory for PBT.

For example, in the case of hexabromobenzene, although it is extremely effective in terms of flame retardancy, it is sublimable, which worsens the working environment and makes processing operations difficult, and the appearance of the resulting molded product lacks gloss. .

Furthermore, tetrabromobisphenol A1 tetrabucomophthalic anhydride and the like color molded products and reduce their commercial value.

Furthermore, the halogen-containing aromatic organic compounds conventionally used exhibit excellent flame retardancy only in a very narrow range of quantitative ratios with antimony trioxide.

As a result of intensive research, the inventors found that the general formula (In the formula, m and n each represent a number from 1 to 3.

) (In the formula, R represents a divalent cross-linking group, and R' has 2 to 2 carbon atoms.
6 divalent hydrocarbon residue, n and m each represent an integer of 1 to 10, X1 to X8 represent a hydrogen atom, a bromine atom, or a chlorine atom, and at least one of X1 to X8
is a bromine atom or a chlorine atom.

) was found to be extremely suitable as a flame retardant for PBT, and the present invention was achieved.

That is, the gist of the present invention is a method for producing a flame-retardant molded article by containing a compound represented by the above general formula and antimony trioxide in PBT and heat-molding the mixture.

The present invention will be explained in detail below.

The PBT applied to the present invention has an intrinsic viscosity (gradient) of 100 ml of a 1:1 mixed solution of phenol and tetrachloroethane.
It is desirable that the measured value of a solution in which 1 g of PBT is dissolved at 30°C is in the range of 0.80 to 1.30, and considering the reduction in intrinsic viscosity during heat molding, it is particularly 1.0.
The above is desirable.

Such PBT is most commonly obtained by transesterifying terephthalic acid dialkyl ester and 1,4-butanediol and then polycondensing them, but it is also possible to directly esterify terephthalic acid and 1,4-butanediol. It can also be obtained by subsequent polycondensation.

As the diol component, 1,4-butanediol is usually used, but 2,3-butanediol, 2,4-butanediol, ■,2-butanediol, etc. are also used, and along with butanediol, ethylene glycol, Glycols such as propylene glycol can also be used in combination.

Furthermore, dicarboxylic acids such as phthalic acid, isophthalic acid, and adipic acid may be used together with terephthalic acid as a dicarboxylic acid component.

In addition, PBT can also be used by blending with other resins as necessary.

In the present invention, the amount of flame retardant to be used is usually 1 to 1 in terms of nologen content of the compound represented by the above general formula based on the total composition.
The content of antimony trioxide is about 1 to 10 by weight.

The ratio of the compound represented by the above general formula to antimony trioxide is not particularly limited, but when considering the appearance of the molded product, if the content of antimony trioxide is too high, the gloss of the surface of the molded product may be reduced. Therefore, the weight ratio of halogen amount/effective antimony is preferably in the range of 1 to 10, particularly 2 to 10.

In the method of the present invention, in addition to these, various auxiliary agents, such as lubricants, heat stabilizers, dyes, pigments, antistatic agents, weatherability improvers, and inorganic substances such as glass fiber and calcium metasilicate, etc. Fillers can also be blended.

The halogen-containing aromatic compound and VB group element compound represented by the above general formula are blended with PBT in a conventional manner, and heated and melted using an extruder to form chips.

Note that it is not preferable to blend these additives before the polycondensation of PBT because the polycondensation reaction does not proceed smoothly and there is a risk of coloring.

PBT chips containing these flame retardants can be molded into molded products of various shapes by various well-known methods such as injection molding and extrusion molding.

Examples 1-5 Polybutylene terephthalate ((v)=i.1) with 2,
2'-bis(3,5-dibromo-4-hydroxyethoxyphenyl)propane powder (abbreviation TBA~EO) (Gr
Eat Lakes BA-50TM) and antimony trioxide were mixed in various amounts, and then kneaded in a 40 mml extruder at a temperature of 230° C. or higher to prepare chips.

In Examples 4 and 5, glass fiber was mixed as a reinforcing material during kneading.

After drying this chip, a combustion test piece (length 127 m, width 12.7717, thickness 1.
5 mm) was molded.

During this molding, the sublimation of the flame retardant onto the mold surface and the color tone of the molded product were visually observed.

The results are shown in Table 1. Note that the color tone of 1 molded product in Table 1 marked with a circle indicates that there is no difference in color tone from the PBT before molding.

In addition, this test piece was sent to Underwriters Laboratory (
Underwriters Laboratory U
The combustion characteristics "vo", "V=1" and "V-" were determined by the vertical combustion test method for material classification established by
2” was investigated.

That is, first, this test piece was held vertically with a clamp, and a flame with a flame length of 2 cm was applied to the lower end twice for 10 seconds each.

This operation was performed on five test pieces to measure the flammability, and the results are shown in Table 1.

Comparative Examples 1 to 4 Flame retardants other than TBA-EO were examined in exactly the same manner, and the results are listed in Table 1.

Note that the upper row of the combustion test results column is the combustion test result when the first 10-second indirect flame was performed.

The bottom row shows the 10% combustion that occurred during the first test and was extinguished.
This is the combustion test result when a second 10-second indirect flame was performed after 10 seconds.

(For items that burn for more than 30 seconds on the first flame contact, 2.
Do not perform a second contact.

) Furthermore, the meanings of each symbol in Table 1 are as follows.

*1 The number before the ▲ symbol in Table 1 indicates the combustion time (seconds) after the gas flame is released.

*2 Burning and non-burning of melted falling polymer is determined by test piece 3o.
Judgment was made based on whether absorbent cotton placed under Cr ignited.

Claims (1)

[Claims] 1. A polybutylene terephthalate resin containing a compound represented by the general formula (in the formula, m and n each represent a number from 1 to 3) and antimony trioxide, and then heated and molded. A method for producing a flame-retardant molded article.