JPH0813877B2 - Manufacturing method of flame retardant polyester - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a flame-retardant polyester, and more specifically, a polyester suitable for a flame-retardant polyester fiber suitable for a blended product with cotton. Of the manufacturing method of.

[Prior Art] From the viewpoint of respect for human beings and fire prevention, various polyester processed moldings are required to be flame-retardant. Polyethylene terephthalate is widely used in clothing, bedding, curtains, jutan, etc., and efforts have been made to deal with it. Conventional methods for imparting flame retardancy to polyethylene terephthalate include (1) a method of chemically or physically adhering or impregnating a flame retardant to the surface or inside of a molded article (post-processing method), (2) during molding Various methods have been proposed, including a method of blending a flame retardant (blending method) and (3) a method of adding and copolymerizing a flame retardant during polyester production (copolymerization method). Among these methods, (3) has a high industrial value without the drawbacks such as deterioration of performance due to washing, textured surface, and exudation of modifier in the manufacturing process. Halogen compounds and phosphorus compounds are known as flame retardants capable of imparting flame retardancy by copolymerization, but phosphorus compounds are superior in terms of light resistance and coloring. In the case of phosphorus compounds, flame retardancy can be imparted to some extent, but in reality it is not yet possible to obtain a high degree of flame retardancy that is satisfactory for all applications in which flame retardancy is required. Particularly in the case of polyester and cotton blended fabric, it is more flammable than a fabric composed of individual fibers. This phenomenon has been explained as a phenomenon of making flammability of polyester due to the framework effect of cotton, and in the case of blended products with cotton, the contribution of the flame retardant modified by the raw yarn is small, so another approach should be considered. (For example, Textile Society of Japan, Vol.34, N
o.12, 1978)).

However, in such a case where the compounding amount of the phosphorus compound is small, a sufficient flame retardant effect cannot be obtained in the case of blending with cotton, and therefore a phosphorus compound capable of introducing a larger amount of phosphorus into the polyester is required.

Here, as the phosphorus compound species, there are many proposals, for example, JP-B-49-22958 discloses that a phosphoric acid ester is copolymerized with a polyester as a phosphorus compound. It is not possible to mix the phosphorus compound up to the amount that imparts the desired flame retardancy because gelation occurs. Further, in the case of JP-A-59-91122, phosphonic acid is used as the phosphorus compound, but the phosphorus compound is often scattered and the desired amount of phosphorus cannot be blended. Further, Japanese Patent Publication No. 53-13479 discloses a polyester blended with the phosphorus compound represented by the formula (1) of the present invention, but this method is advantageous for gelation and scattering of the phosphorus compound. However, there is a drawback that the original physical properties of polyester are deteriorated as a large amount is blended. Probably because the crystallinity of the polyester is lowered, a high draw ratio is required to obtain the desired yarn characteristics because the superdraw phenomenon is likely to occur during the drawing process, which causes problems such as yarn breakage and fluffing. Cause a decrease in sex. Also, there is a problem that the fabric shrinks when exposed to high temperatures in the dyeing process and finishing setting process after the fabric is made, probably because the shrinkage rate of the yarn becomes large, and a soft texture is required. It has the drawback that it cannot be applied to the fields in which it is located.

The present inventors have conducted extensive studies in order to eliminate the above-mentioned drawbacks of the prior art, and by adding a large amount of a specific phosphorus compound and a specific amount of a specific metal compound at the time of polyester production, a polyester fiber alone, Alternatively, they have found that a composite with cellulose fibers can satisfy both excellent flame retardancy and good texture, and completed the present invention.

[Problems to be Solved by the Present Invention] The object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to satisfy both excellent flame retardancy and good texture in polyester fiber alone or in a composite with cellulose fiber. The purpose is to propose a method for producing flame-retardant polyester.

[Means for Solving Problems] The above-mentioned object of the present invention is to produce a polyester whose main constituent unit is ethylene terephthalate,
A phosphorus compound represented by the following formula (1) is added so that the phosphorus element content in the polyester is 0.8 to 3.0% by weight, and at least one metal compound selected from a Mg compound, a Li compound and a Ca compound. Can be achieved by a method for producing a flame-retardant polyester, which comprises adding an amount satisfying the following formula (2).

The present invention will be described in detail below.

As the phosphorus compound (1) in the present invention, (2-carboxyethyl) methylphosphinic acid, (2-methoxycarbonylethyl) methylphosphinic acid, [2- (β-
Examples of preferred compounds include hydroxyethoxycarbonyl) ethyl] methylphosphinic acid, methyl (2-methoxycarbonylethyl) methylphosphinic acid, and ethylene grillol ester of [2- (β-hydroxyethoxycarbonyl) ethyl] methylphosphinic acid. Is a heating reaction product of an intramolecular cyclic anhydride of 2-carboxyethylmethylphosphinic acid and ethylene glycol. Alternatively, a substance obtained by further condensing this reaction product is also preferable.

The phosphorus compound of the present invention is added at the time of polyester production, but is added so that the phosphorus atom content in the polymer is 0.8 to 3.0% by weight. It is preferably 1.0 to 2.0% by weight.
If the addition amount of the phosphorus compound is less than this range, the flame retardancy is poor, and the flame retardancy is not sufficient even if a flame retardant is added by a post-addition processing method to a mixed fabric with cotton. On the other hand, when the amount of the phosphorus compound added is larger than the above range, the physical properties of the polyester obtained by the addition of the metal compound of the present invention are significantly deteriorated, which is not preferable. Regarding the method of adding the phosphorus compound in the polyester production step, either during the esterification reaction or during the polycondensation reaction may be performed, but the polycondensation time is extended by the problem of the contamination of the esterification reaction can or the latter stage of the polycondensation reaction. From the viewpoint of the above, it is effective to add it after the completion of the esterification reaction and during the initial stage of the polycondensation. Furthermore, when the phosphorus compound of the present invention is mixed with a polycondensation catalyst and added, a slight decrease in polycondensation reactivity is observed. Therefore, the phosphorus compound is added to the polyester production system, and after aging for 1 to 20 minutes, the polycondensation catalyst is added. Is preferably added. It is also a preferable method to add the phosphorus compound after previously mixing or dissolving it in the diol component or other solvent or condensing it under heat.

Metal compounds used in the present invention are Mg, Li, Ca
Among them, hydroxides, carbonates, acetates and the like of the metals selected from the above, magnesium acetate, lithium acetate and calcium acetate are particularly preferable compounds from the viewpoint of dissolution in the reaction system.
It is necessary to add one or more of these metal compounds in an amount satisfying the following formula (2) in relation to the phosphorus compound.

In the above formula (2), the addition amounts of the metal element and the phosphorus element in the metal compound and the phosphorus compound are terephthalic acid when the polyester is produced by the direct esterification reaction method.
It is parts by weight with respect to 100 parts by weight, and when it is produced by the transesterification method using dimethyl terephthalate, it is calculated using the value obtained by converting dimethyl terephthalate to terephthalic acid. For example, when the amount of elemental phosphorus added is 1 part by weight with respect to 100 parts by weight of terephthalic acid, the lower limit addition amount of M is (1/2200) + 6.4 × 10 ⁻⁴ ≦ M and M ≧ 1.09 × 10 ^{− 3} (parts by weight) The upper limit of M is (1/22) + 6.4 × 10 ^-2 ≥ M, and M ≤ 1.09 × 10 ^-1 (parts by weight). Is 1.09 ×
If the amount is less than 10 ^-3 parts by weight, the degree of orientation and intermolecular interaction of the polyester undrawn yarn obtained by spinning may be low, and the crystallinity due to stretching may be low. Even if a drawing condition that avoids is adopted, the obtained drawn yarn has a large shrinkage ratio, so that the yarn and the cloth after the heat setting (160 to 180 ° C.) step are hardened to have a rough texture.

The addition amount of the metal compound as a metal element is 1.09 × 10.
-If the amount is more than ¹ part by weight, coloring of polymer and generation of foreign matter,
This causes poor dispersibility of the metal compound and leads to yarn breakage during spinning.

As described above, it is an important point to select the addition amount of the metal compound in a preferable range corresponding to the addition amount of the phosphorus compound.

Regarding the method of adding the metal compound in the polyester production step, it is possible to add the metal compound at any stage of the polycondensation reaction during the esterification reaction. In the latter-stage addition, it is preferable to add it after the completion of the esterification reaction and in the early stage of the polycondensation, as in the case of adding the phosphorus compound, from the viewpoint of extending the polycondensation time.

Further, it is preferable that the metal compound is previously dissolved or dispersed in the diol component which is a raw material for producing polyester and then added in the form of a solution or a slurry.

In the present invention, the polyester whose main structural unit is ethylene terephthalate is 70% by mole or more of repeating structural units is ethylene terephthalate, terephthalic acid or dimethyl terephthalate and ethylene glycol are used as raw material components, and the above-mentioned ( The phosphorus compound represented by the formula 1) is used, but in addition to this, isophthalic acid, 2,6
-Aromatic dicarboxylic acids such as naphthalenedicarboxylic acid and 5-sodium sulfoisophthalic acid, aliphatic dicarboxylic acids such as adipic acid and sebacic acid, diethylene glycol,
Trimethylene glycol, tetramethylene glycol,
It is also possible to use neopentyl glycol, 1,4-cyclohexanediol, polyethylene glycol, or a diol compound represented by the following formula in combination as a copolymerization component.

The flame-retardant polyester of the present invention can be produced by a conventionally known method. For example, terephthalic acid and ethylene glycol under normal pressure or under pressure of about 3 kg / cm ² to 200-270
The esterification reaction is carried out at a temperature of ℃, the phosphorus compound represented by the formula (1) and the metal compound described above are added to the reaction product, and after aging for 10 minutes, antimony trioxide known as a polycondensation catalyst is added. Is added to gradually increase the temperature while maintaining a high vacuum of 1 mmHg or less, and carry out a polycondensation reaction at a temperature of 250 to 300 ° C. Furthermore, the method for producing fibers using polyester is a conventionally known method,
Although it is not particularly limited, the texture is not hardened by the heat treatment in the dyeing step or the finishing setting step after the fiber is processed into a polyester single type or a polyester or cellulose composite fabric or a twisted yarn. It is desirable to control the dry heat shrinkage of the polyester fiber to 20% or less, more preferably 15% or less,
The object can be achieved by setting the spinning speed to 1200 m / min or more, the drawing temperature to 70 ° C or more, and the heat treatment temperature after drawing to 160 ° C or more.

When the flame-retardant polyester fiber is produced by the present invention, commonly used additives such as tetraethylammonium hydroxide which is an ether bond inhibitor, titanium dioxide which is a matting agent, and other antimony trioxide are difficult to be used. It is also possible to add a combustion aid, carbon black, an antistatic agent, a heat stabilizer, etc. in combination.

Further, it is also possible to process the polyester of the present invention into a fibrous state, form a fabric of a composite with celluloses, and then add a phosphorus compound or a halogen compound flame retardant by a post-processing method. The treated fabric can have a higher degree of flame retardancy and a good texture.

Specific examples of compounds that are particularly effective as flame retardants used in post-processing include tetrakishydroxymethylphosphonium chloride / trimethylol melamine / urea, vinylphosphonate oligomers / N-methylol acrylamide, N
-Methylol dimethylphosphonopropionamide and the like.

[Examples] The present invention will be described in more detail with reference to Examples below, but the present invention is not limited thereto.

The parts in the examples are parts by weight, and the physical properties of polyester fibers were measured as follows.

A. Intrinsic viscosity (IV) Measured at 25 ° C. using O-chlorophenol as a solvent.

B. Phosphorus content It was measured by a colorimetric method.

C. Dry Heat Shrinkage A load of 0.4 g per 1 denier of single yarn is applied, and after measuring the sample length l _{0, it} is treated for 20 minutes in a hot air thermostat at 180 ° C. under no load. After cooling, a load of 0.4 g per 1 denier is applied again, and the sample length l ₁ is measured, and calculated by the following formula.

Dry heat shrinkage (%) = (l ₀ -l ₁ ) / l ₀ × 100 D. Texture A fabric prepared in the same manner as in the example by using ordinary polyethylene terephthalate fiber not containing a large amount of phosphorus.
And the hardness degree of the fabric is compared with the unprocessed fabric prepared in the same manner as in the example by using the spun yarn composed of the usual polyethylene terephthalate fiber and cotton, and the hardness degree of the fabric is determined by the following three steps according to the feel of the finger. evaluated.

◎ Equivalent.

○ A little hardness is felt.

× Hardness is clearly felt.

E. Flame retardance "45 ° coil method (1)" was measured according to JIS L-1091D method.

The "45 ° coil method (2)" is performed according to JIS L-1091D method, but the coil used has a pitch of 1 mm. 1
By using the mm pitch coil, digestion due to the phenomenon of taking away the flame due to the melting and falling phenomenon of polyester is eliminated,
Can evaluate self-digestion ability.

The "45 ° micro-burner method" was measured according to JIS L-1091A-1 method.

The "vertical method" was measured according to JIS L-1091A-4 method.

Example 1 and Comparative Example 1 Bis-β-hydroxyethyl terephthalate and its low polymer at 250 ° C. obtained by a direct esterification method using 100 parts of terephthalic acid and 48.6 parts of ethylene glycol are shown in Table 1.
A predetermined amount of the metal compound shown in 1 was added as a 10 wt% ethylene glycol solution, and the mixture was stirred for 5 minutes. Subsequently, a predetermined amount of a reaction product (phosphorus content 11.6% by weight) obtained by heating and reacting a mixture of 2-carboxyethylmethylphosphinic acid intramolecular cyclic anhydride and ethylene glycol at a ratio of 1: 1 by weight at 120 ° C was added. And mixed for 10 minutes with stirring. Thereafter, 0.05 part of antimony trioxide and 0.6 part of titanium dioxide were added as an ethylene glycol slurry, and then the temperature was gradually raised and the pressure was reduced. Finally, polymerization was performed at 288 ° C. and 0.3 mmHg for 1 to 5 hours to a predetermined viscosity. The same polymerization was repeated while changing the kind and amount of the metal compound and the addition amount of the phosphorus compound shown in Table 1. Table 1 shows the intrinsic viscosity of the obtained polyester and the phosphorus content in the polymer. Then
The polyester thus obtained was subjected to a conventional method at a spinning temperature of 285 ° C.
Was spun and wound at a speed of 1500 m / min to obtain an undrawn yarn. Each undrawn yarn was bundled into a tow of about 500,000 denier in terms of drawn yarn. Liquid bath drawing was performed at a liquid bath temperature of 75 ° C. and a draw ratio of 3.5 to 4.5 so that the residual elongation of the drawn yarn was about 30%. Subsequently, a constant length heat treatment was carried out for about 5 seconds on a heating drum at 165 ° C., crimping was applied, and after drying at 120 ° C., cut into 38 mm to obtain short fibers. Table 1 shows the number of yarn breakages in the spinning process and the dry heat shrinkage ratio of the obtained short fibers. Using this short fiber, a spun yarn is made by a normal method, and the basis weight is 250 g / m ²
Table 1 shows the texture and flame retardancy evaluation results of the plain woven fabrics, each of which was heat-set at 180 ° C. for 1 minute at a fixed length and washed and dried.

In Experiment No. 4 and Experiment No. 6 of Comparative Example 1, there were many foreign substances due to the metal compound and many yarn breakages occurred during spinning, but all of the present inventions have good flame retardancy and texture. . In particular, the flame retardancy of the 45 ° coil method (2) that suppressed melt drop was good.

65% by weight of polyester short fibers and 35% by weight of cotton
No. 30 blended yarn consisting of and was prepared, and then a plain weave having a basis weight of 250 g / m ² was prepared, and heat set at 180 ° C. for 1 minute under constant length.

Table 2 shows the feeling and flame retardancy evaluation results after the fabric was washed and dried.

Even in the case of blended yarn with cotton, the range of the present invention is 0.8% phosphorus.
˜3.0%, a fabric using polymer levels 1 to 7 in combination with a specified amount of a metal compound, Experiment No. 8 to 14 of Example 1.
It is clear that each of them has a good texture and a high degree of flame retardancy.

Fabric made of the above polyester and cotton (Experiment No. 8-14)
Was impregnated with the following flame retardant, and after wet heat treatment at 103 ° C for 5 minutes,
It was washed with water and dried. The amount of the flame retardant attached to the fabric was calculated by the change in weight before and after processing.

Table 3 shows the texture after the flame-retardant post-processing and the flame-retardant evaluation results.

Fabrics having a phosphorus content in the polyester of 0.8 to 3.0% by weight and a post-processed fabric in which an amount of the metal compound specified in the present invention is used in combination (Experiment No. 15 to 21 of Example 1) are all good. It is clear that it shows a texture and a high degree of flame retardancy.

[Effects of the Invention] The polyester obtained by the method for producing a polyester of the present invention contains a specific amount of a phosphorus compound and a specific metal compound, and therefore has a high flame retardancy and a texture which have not been obtained in the past. It can be fiber. Especially in the field of blended products such as cotton, by using post-combustion flame-retardant treatment together, it becomes possible to use even clothes and work clothes that were not possible to advance in terms of texture and flame-retardant performance.

Claims (1)

[Claims] 1. When producing a polyester whose main constituent unit is ethylene terephthalate, a phosphorus compound represented by the following formula (1) is added so that the phosphorus element content in the polyester is 0.8 to 3.0% by weight, A method for producing a flame-retardant polyester, which comprises adding at least one metal compound selected from a Mg compound, a Li compound and a Ca compound in an amount satisfying the following formula (2). [Wherein R ₁ and R ₂ represent an alkyl group having 1 to 18 carbon atoms, an aryl group, a monohydroxyalkyl group or a hydrogen atom, R ₃ represents an alkyl group or an aryl group, and A represents (C _n H _2n ). , And n
Represents an integer of 1 to 4. ] (P / 2200) + 6.4 × 10 ⁻⁴ ≦ M ≦ (P / 22) + 6.4 × 10 ⁻² ………… (2) [In the formula, P is based on 100 parts by weight of the phosphorus compound terephthalic acid. The addition amount as a phosphorus element (parts by weight), M represents the addition amount as a metal element (parts by weight) relative to 100 parts by weight of terephthalic acid of the metal compound. ]