JPS6221923B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an artificial lawn made of polyamide pile yarn having excellent chlorine resistance. Conventionally, polyamide fibers, typified by aliphatic polyamides such as nylon 6 and 66, have been commercially produced and sold due to their excellent mechanical strength, silk-like luster and feel, and color clarity. However, the initial elastic modulus is low and there is no so-called waist.
It has drawbacks such as being prone to wrinkles and poor dimensional or morphological stability when wet, which has been problematic in various application fields or has been considered unusable. Particularly in recent years, many swimming and golf courses have installed artificial turf next to the pool or in shower rooms. A disinfectant consisting of oxidizing chlorine is used in the disinfection treatment, and the aliphatic polyamides that make up artificial lawns, such as nylon 6 and 66, are significantly degraded by this treatment and even become crumbly. The present invention improves the drawbacks of such conventional artificial lawns,
The present invention provides an artificial lawn made of a specific polyamide pile yarn that has excellent chlorine resistance while retaining the excellent properties of aliphatic polyamide. The present invention has the following technical configuration to achieve the above object. That is, an aliphatic copolyamide consisting of a dicarboxylic acid in which at least 15 mol% of the acid component is an aromatic dicarboxylic acid and hexamethylene diamine, and the difference between the cold crystallization temperature and the glass transition temperature is 40°C or less. The initial tensile resistance formed by 40
This is an artificial lawn made of pile yarn of g/d or more. By adopting such a technical configuration, we were able to stably provide, for the first time, an artificial lawn that not only has chlorine resistance but also has excellent resistance to settling, wrinkles, weather fastness, and dimensional stability. The copolyamide fiber of the present invention not only has durable chlorine resistance, but also improves the initial elastic modulus, which is said to be a drawback of fibers made of aliphatic polyamides such as nylon 6 and 66, and has acid resistance and weather resistance. It has also been improved in terms of speed, etc. In other words, polymers such as aliphatic polyamides in which a methylene group (-CH ₂ -) or a methyl group (-CH ₃ ) is bonded adjacent to the carbonyl group of the amide group constituting the polymer chain are generally oxidized. However, in order to reduce and prevent the deterioration of polyamide due to oxidizing chlorine, the present invention aims to reduce and prevent the deterioration of polyamide due to oxidizing chlorine. polymerized units at least
By copolymerizing 15 mol%, preferably 20 to 50 mol%, a copolyamide exhibiting practically sufficient chlorine resistance can be obtained, and its initial elastic modulus is improved compared to the aliphatic polyamide fiber. This is what we discovered. Furthermore, the copolyamide constituting the fiber of the present invention not only has at least 15 mol% of the copolymerized units, but also has a cold crystallization temperature (T _c ) and a glass transition temperature (T _g ) measured by the method described below. ) It is important that the difference (ΔT _cg ) ΔT _cg = (T _c - T _g ) is 40° C. or less. That is, in the present invention, a copolyamide having at least 15 mol% of copolymerized units consisting of the aromatic dicarboxylic acid and hexamethylene diamine as a copolymerization component of the polyamide is used, for example, when the copolymerization component is terephthalic acid, isophthalic acid, etc. It can be obtained by copolymerizing copolymerized units of aromatic dicarboxylic acid and hexamethylene diamine. However, in cases such as 66/6T copolyamide containing hexamethylene adipamide (66) and hexamethylene terephthalamide (6T), an isomorphic substituted copolymer is formed, resulting in an excessively crystalline, high melting point polymer, which is unstable. Not only will polymerization not be possible, but melt spinning will become difficult, and the flexibility and water absorption of the resulting fibers will decrease, making it impossible to fully reflect the characteristics of polyamide fibers. On the other hand, hexamethylene isophthalamide (6I) consisting of isophthalic acid and hexamethylene diamine
Copolymer of 6/6I and 66 with poly-ε-caprolamide (nylon 6) whose units are copolymerized units 66/
6I is a non-isomorphic substitution type copolymer, and the melting point can be lowered by copolymerizing 6I units, and as the copolymerization ratio increases, the T of the copolymer increases.
Although _g increases, the crystallinity decreases significantly, which is not preferable in terms of dimensional stability and chemical resistance. Therefore, the present invention provides that in an aliphatic copolyamide fiber containing a copolymerized unit consisting of such an aromatic dicarboxylic acid and hexamethylene diamine, the ΔT _cg of the copolyamide constituting the copolyamide satisfies the above conditions. Only by doing so can the object of the present invention be achieved. Here, ΔT _cg defined in the present invention is determined by the following method. For example, Hitachi's DSC (differential scanning calorimeter):
The polymer was melted by heating and then rapidly cooled in liquid nitrogen using a Deffarential Scanning Colorimeter, and the resulting solidified polymer was heated at a rate of 10°C/min.
Crystalligation) temperature is _Tc , and _Tg is the glass transition temperature (secondary transition temperature) measured at that time.
It is. Therefore, ΔT _cg is the difference between T _c and T _g determined above, and is calculated as T _c −T _g (=ΔT _cg ). ΔT _cg determined by the above formula is a measure of the crystallinity of the copolyamide, and the smaller this value, the greater the crystallinity of the copolymer. This copolyamide with a ΔT _cg of 40°C or less is a copolymerized unit consisting of an aromatic dicarboxylic acid and hexamethylene diamine, for example, when the aromatic dicarboxylic acid is terephthalic acid and/or isophthalic acid, hexamethylene terephthalamide is used. (6T), hexamethylene isophthalamide (6I), hexamethylene terephthalamide/hexamethylene isophthalamide (6T/6I) units, etc. by selecting the copolymerization ratio. When the above copolyamide is a crystalline polymer at a ΔT _cg of 40°C or less, preferably 35°C or less, the copolyamide filament can tolerate strong deterioration due to active chlorine ions, and the initial Young's modulus and Dimensional stability can be improved. As a method for producing the copolyamide of the present invention, the copolymer can be obtained by polycondensation using a known melt polymerization method. For example, when producing a 66/6T copolyamide, 66 nylon salt from hexamethylene diamine and adipic acid and 6T from hexamethylene diamine and terephthalic acid are used.
A method of melt polymerization by mixing nylon salt so that the 6T salt is 15 mol% or more, or a method of mixing dicarboxylic acid with 85 mol% or less of adipic acid with 15 mol% or more of terephthalic acid and hexamethylene diamine. A method such as forming a 66/6T mixed nylon salt and melt polymerizing it can be adopted depending on the conditions of the equipment and equipment. The thus obtained copolyamide of the present invention can be spun by a known melt spinning method and made into fibers through steps such as stretching and heat treatment. In other words, the filament for artificial lawns uses the usual monofilament spinning process, but in order to flatten the cross-sectional shape of the filament so that it approaches that of natural grass, it is preferable that the molten polymer has a high viscosity, and η _r is 2.4 or more. It is better. If η _r is lower than this, even if you try to make the nozzle flat by designing the nozzle, not only will the nozzle hole become clogged and productivity will deteriorate, but the shape will not be maintained even after being discharged, and the shape will not be round by the time it solidifies. It becomes something close to. Therefore, in order to maintain a high degree of flattening, a copolymer with a higher η _r is preferred, and a copolymer with an η _r of 2.5 or more is preferably used. As mentioned above, the copolyamide fiber of the present invention has excellent chlorine resistance, abrasion resistance, fibrillation resistance, and dyeability, as well as improved initial elastic modulus. It has excellent practical performance as a monofilament, especially as a flat monofilament useful for piles of artificial turf. Example 1 Hexamethylene diammonium adipate (66
Mixed nylon salts of 65 mol% nylon salt) and 35 mol% hexamethylene diammonium terephthalate (6T nylon salt), and 49 mol% 66 nylon salt and 31 mol% 6T nylon salt and hexamethylene diammonium isophthalate (6I nylon salt) )20
66/6T (65/35) and 66/6T/6I from mol% mixed nylon salts by conventional melt polymerization method.
Semi-aromatic copolymerized nylon (49/31/20) was synthesized. Degree of polymerization (η _r at 1% concentration in concentrated sulfuric acid)
were 2.48 and 2.51, respectively. For comparison, nylon 66 (η _r
= 2.50) was synthesized. The properties of these polyamides were as shown in Table 1.

[Table] Each of these polymers was subjected to normal melt spinning and stretching.
A multifilament yarn of 50 denier 12 filaments was obtained. The strength (T), elongation (E), and initial Young's modulus (Y) of this yarn were measured and were as shown in Table 1. Note that the values in parentheses for Y in Table 1 are measured values in water. As is clear from Table 1, the comparative example of nylon 66
It can be seen that the initial Young's modulus is low, and especially the Young's modulus in water is extremely low for nylon 66 compared to the example of the present invention. Next, the chlorine resistance of these three samples was examined. Each multifilament was immersed in a sodium hypochlorite (NaClO) aqueous solution (antiformin) with an active chlorine concentration of 0.5% with a load of 2 mg per unit denier. After a certain period of time had elapsed, the filament was pulled out of the solution, gently washed with running water, and air-dried.
When the tenacity of each sample yarn was measured, the results shown in Table 2 were obtained.

[Table] In Examples A and B of the present invention, the chlorine solution treatment time was 200
It shows a tenacity retention rate of more than 90% even after hours, whereas the strength of the comparative yarn nylon 66 is 1/1.
It is clear that the number has dropped to nearly 2. In addition, in the examples of the present invention, it is considered that the B yarn may have a higher strength retention rate than the A yarn in view of the high T _g and the large amount of aromatic core components. However, as mentioned in the text, this means that ΔT _cg is A
Since it is made of a copolymer that is much larger than the yarn, it probably makes yarn B less durable against chlorine deterioration. Therefore, it can be seen that it is also an important factor that the filament is made of a copolymer with a low ΔT _cg . Example 2 70/30 mol% of 66/6T in the same manner as Example 1
A copolymer was synthesized. For comparison, nylon 6 was synthesized from ε-caprolactam. The polymer properties of each were as shown in Table 3.

[Table] Using this polymer, a green pigment was added for artificial turf, and thick filaments were obtained by melt spinning and moist heat stretching. Five monofilaments of 200 to 300 deniers were combined and twisted 120 times per meter, and two of these twisted yarns were combined and twisted 60 times to form a filament bundle. In this state, the chlorine resistance of the filament was measured in the same manner as in Example 1, and the results shown in Table 4 were obtained.

[Table] The ΔT _cg of D and E are almost the same, but D has a higher T _g and an aromatic nucleus component is introduced into the molecular chain, so it has a high retention rate during chlorine aqueous solution treatment and is highly resistant to deterioration. You can see that there is some resistance. Next, this twisted yarn was used for tufting to create artificial turf from a pile sheet. A fatigue experiment was conducted on this lawn according to the prescription of JIS L1021, and the results shown in Table 5 were obtained. In addition, when conducting the sagging test, a lawn was set in steam at 130°C for 15 minutes and then measured for comparison.

[Table] Table 5 also lists the measured boiling water shrinkage rates of the yarns. As is clear from the above table, it can be seen that the artificial lawn of the present invention has extremely excellent resistance to settling.
Even without steam set, it shows a resistance to set that is comparable to the steam set product of E. Furthermore, it is clear that the boiling point value is extremely low and the dimensional stability is excellent.

Claims (1)

[Claims] 1. An aliphatic copolyamide consisting of a dicarboxylic acid in which at least 15 mol% of the acid component is an aromatic dicarboxylic acid and hexamethylene diamine, and in which the difference between the cold crystallization temperature and the glass transition temperature is 40°C or less. Artificial grass made of pile yarn with an initial tensile resistance of 40 g/d or more.