JPS591715A - Copolyester binder fiber - Google Patents

Abstract

PURPOSE:A copolyester binder fiber that has lower than specific values in its melting point, glass transition point and elastic deformation point, thus showing dood handleability, high adhesion as a binder and low shrinkage of its collective fiber, when heat treated for adhesion. CONSTITUTION:A copolyester having lower than 200 deg.C melting point, lower than 40 deg.C glass transition point, less than 10 elastic deformation factor, preferably containing terephthalic acid isophethalic acid, 1,4-butanediol and glycol components other than polyether is subjected to melt spinning at a temperature 50- 150 deg.C higher than the melting point and, when needed, drawn at a draw ratio of 1.1-3 at 30-60 deg.C to produce the objective copolyester binder fiber. USE:Nonwoven fabrics or wadding.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has excellent adhesive properties for use as a binder, and has high IJ resistance during adhesive heat treatment. This invention relates to copolymerized polyester binder fibers with small fiber aggregate shrinkage.

Adhesives conventionally used in the fields of nonwoven fabrics, padding, rugs, etc. are mostly emulsion type or solvent type adhesives made of synthetic rubber, allylic acid ester, etc. However, recently, non-emulsion-based, non-solvent-based hot melt adhesives that are superior in cost/performance ratio have been attracting attention from the viewpoint of energy saving and pollution prevention. In particular, fibrous hot-melt adhesives (binder fibers) are expected to become important materials in the fields of nonwoven fabrics, padding, rugs, etc. in the future. As such a binder fiber, E made by Chisso ■ is already available.
There is S fiber, whose core component is polypropylene.

It is a polyolefin eccentric core-sheath type composite fiber whose sheath component is polyethylene. This ES fiber exhibits a considerably strong adhesion effect on fiber aggregates whose main fibers are polyolefin, but
The adhesive effect on fiber aggregates mainly composed of & fibers is very small. Therefore, it is necessary to add 30% by weight or more, and as a result, there is a drawback that the characteristics of the main fiber are lost. In particular, the extremely low adhesive effect on polyester fibers, which are considered to be most adaptable to future advances in industrial structure, is considered to be a serious drawback.

Furthermore, JP-A-57-66117 describes an example of a polyester binder fiber made of terephthalic acid, isophthalic acid, and ethylene glycol.
The binder fiber is of poor quality and has a glass transition point of 60~
Because it is as high as 70℃, it is extremely brittle and difficult to handle.
There is a drawback that the fibers are likely to break and fall off during the force-loading process.

Also, KFi, terephthalic acid, isophthalic acid, aliphatic dicarboxylic acid disclosed in JP-A-57-21513.

Hot-melt adhesive fibers made of ethylene glycol and 1,4-butanediol have been disclosed, but these fibers are highly sticky and have poor handling properties, and when mixed into a fiber aggregate and used as a binder fiber, However, there is a problem in that the fiber aggregate shrinks too much during adhesive heat treatment, resulting in a shrink layer.

The present inventor has found that it has an excellent adhesive effect on polyester fibers, does not cause a shrink layer in the fiber aggregate when used as a binder fiber in the fiber aggregate, and is easy to handle. As a result of extensive research into copolymerized polyester fibers for excellent binders, the present invention was arrived at. That is, the melting point of the present invention is 200°C or lower.

The glass transition point is 40℃ or less, and the elastic deformation index is 1.
It is a copolymerized polyester binder fiber characterized by a grain density of 0 or less, and its purpose is not only to have an excellent adhesive effect, but also to have excellent handling properties and to improve fiber aggregation during adhesive heat treatment. It is an object of the present invention to provide a polyester fiber for a binder that exhibits small body shrinkage.

The melting point in the present invention is determined using a DuPont Differential Thermal Analyzer 99.
Using type 0, the sample amount was 10cm.

Temperature increase rate: 20°C/-, N, which is the endothermic peak temperature due to crystal melting that appears when the temperature is increased in an atmosphere. This melting point is important when setting the adhesive heat treatment temperature of the fiber aggregate containing M# for the binder, and needs to be 200°C or less, preferably 180°C or less. It goes without saying that the lower the melting point, the more preferable it is in terms of energy cost, but in practice, a melting point of 100° C. or higher is preferable.

In addition, the glass transition point in the present invention is determined by heating the glass to above the melting point under the same conditions using the same equipment used to measure the melting point, quenching it in water, and then raising the temperature under the same conditions as the melting point measurement. This is the starting point of endotherm due to glass transition when heated. This glass transition point needs to be 40°C or lower; if it exceeds 40°C, the resulting fibers become brittle, resulting in a problem that the fibers are easily cut during the carding process, for example.

Furthermore, the present inventors have conducted intensive studies on the shrinkage phenomenon during thermal bonding of fiber aggregates containing copolymerized polyester fibers for binders (the bonding heat treatment temperature is usually set 10 to 50°C higher than the melting point). As a result, they found that the "elastic deformation index (hereinafter referred to as γe)", which will be explained below, has a decisive influence. Now, if we consider the phenomenon in which polymers become thinner in sequence during the melt-spinning and drawing processes, the polymer chains undergo elastic deformation of the polymer chains themselves and plastic deformation due to slippage between the polymer chains during each process. It is thought that it will become smaller.

However, if the polymer chains that undergo this elastic deformation are brought into a state where their free energy is zero, that is, above their melting point, they should recover to their original state. Therefore, the present inventors treated the fibers at a temperature of +20°C to the melting point, and developed an "elastic deformation index (γ
e)'' and examined the correlation with shrinkage of the fiber aggregate during adhesive heat treatment, and found that they corresponded very well. This γe is measured and calculated as follows. In other words, the copolymerized polyester fiber has a melting point of +
Relaxation treatment is performed for 30 seconds in silicone oil adjusted to a temperature of 20°C, and the length of the fibers before and after treatment is determined by the following formula.

LO Elastic deformation index (γe) = □ Here, LO is the length of the fiber at room temperature before treatment, and L is the fiber length in silicone oil after treatment (a 100-mesh wire mesh is placed in the silicone oil path, This is the length of the fiber after it is taken out from the fiber (processed) and left to cool to room temperature.

The copolymerized polyester binder counterfeit of the present invention has this γ
It is necessary that e be 10 or less, preferably 9 or less. If γe is larger than 10, the shrinkage of the fiber aggregate will increase when the fiber aggregate containing binder fibers is subjected to adhesive heat treatment. In particular, when fiber aggregates such as webs, web AM bodies, slivers, etc., which have a small binding force, are subjected to relaxation heat treatment at a temperature higher than the melting point of the binder fibers and bonded together, the shrinkage becomes large. As a result of eleven studies regarding this contraction,
If the sliver shrinkage rate, which will be described later, is 20% or less, there will be little problem, but if it exceeds 20%, shrinkage spots will become noticeable and quality variations will increase, which is not preferable. For example, in the case where a web including an inder ff1m is heat-treated for bonding with hot air, a "waving phenomenon" of the web is likely to occur.

The melting point (hereinafter referred to as Tm) of the copolymerized polyester fiber of the present invention is 200°C or lower, preferably 100 to 180°C. Generally, the Tm of a crystalline polymer is determined by the flexibility, symmetry, and It is said to be determined by cohesive energy density, side chains (polarity and flexibility of side chains), etc., and is defined by the following formula.

Tm = ΔH/ΔS In this formula, " is the enthalpy of melting, and ΔS is the entropy of melting. Further, the decrease in Tm of the random copolymer can be determined by the following formula.

Tm Tm' ΔH where Tnf is the melting point of a pure homopolymer with infinite molecular weight, R is the gas constant, and xh is the mole fraction of comonomer A (crystallizable monomer orientation) in the copolymer. It is.

Furthermore, the glass transition point (
(hereinafter referred to as Tg) is 40°C or less, but the Tg mentioned above
Some of the relationships between m and polymer structure also hold true for Tg. That is, Tg is the flexibility, symmetry, cohesive energy density, steric hindrance, and side chain (bulkness, flexibility) of the polymer chain.
It is said that it is determined by Also, the Tg of the copolymer
has a Tg intermediate to that of pure homopolymers, e.g.
The volume fractions corresponding to components 1 and 2 are vI and v, respectively.
2, the Tg of the copolymer is determined by the following formula.

T g=VI TKl+ V* Tgz The polyester used for the polyester fiber of the present invention is most often obtained by random copolymerization of various compositions. The acid components of the polyester include terephthalic acid, isophthalic acid,
Paraoxybenzoic acid, cyclohexanecarboxylic acid, naphthalene dicarboxylic acid, adipic acid, sebacic acid, succinic acid, etc. and lower alkyl esters thereof are considered, and glycol components include L ethylene glycol, propylene glycol, 1,4-butanediol, Possible monomers include diethylene glycol, triethylene glycol, tetraethylene glycol, neopentyl glycol, etc., and by combining various types of these monomers and their copolymerization ratios, the melting point and Tg can be changed quite arbitrarily.

For example, terephthalic acid-isophthalic acid-1,4-butanediol copolymer, terephthalic acid-isophthalic acid-ethylene glycol-1,4-butanediol copolymer, terephthalic acid-isophthalic acid-ethylene glycol-diethylene glycol copolymers, terephthalic acid-adibic acid-ethylene glycol-1,4-7 tanediyl copolymers, etc., but from the viewpoint of adhesiveness, melt spinnability, and stretchability, terephthalic acid components and isophthalic acid components are preferred.

A copolymerized polyester consisting of a glycol component other than 1,4-butanediol and polyether is suitable.

These copolyesters can be obtained by polymerization according to conventional methods for producing polyesters.

The copolymerized polyester binder fiber of the present invention is produced under different conditions from that of polyethylene terephthalate polyester fiber, which is a normal polyester fiber. That is, while the melt spinning temperature for polyethylene terephthalate-based polyester fiber is set 10 to 30°C higher than its melting point (Tm), the melt spinning temperature for the polyester fiber of the present invention is set 50 to 150°C higher than its melting point (Tm). Ru.

In addition, the temperature and magnification during stretching, which is carried out as necessary, are 60 to 80°C and 3 to 6 times that of polyethylene terephthalate polyester fiber, whereas
The copolymerized polyester fiber of the present invention is heated at 30 to 60°C, 1.
It is 1 to 3 times as much, which is quite low. In the copolymerized polyester fiber of the present invention, fibers tend to stick together depending on the composition of the copolymer and the copolymerization ratio.

In that case, it is effective to deposit an alkyl phosphate metal salt or a surfactant containing it on the fiber surface as a spinning oil, drawing oil, or finishing oil. Particularly suitable is the potassium lauryl phosphate salt.

When the copolymerized polyester fiber for binder of the present invention is applied to a sand fiber aggregate mainly composed of polyester fiber,
It exhibits especially excellent adhesive strength and at the same time has low shrinkage.
It is particularly suitable for nonwoven fabrics and cotton padding. Various general physical properties of fibers are designed depending on their use.

For example, for paper making, a non-crimped fabric with a fineness of 0.1 to 10 deniers and a fiber length of 1 to 20 m is suitable, and is suitable for dry nonwoven fabrics and padding. For 8 (hard cotton, etc.), the fineness is 0.5 to 20 denier.

Fiber length is 20-120m+n, number of fibers is 5-20/
25 mm is preferably used, but it is not particularly limited. Further, the blending amount of the binder #I fiber of the present invention is usually 3 to 30% by weight, but in order to balance adhesive strength and shrinkage, it is particularly suitable for the button to be 7 to 20% by weight.

However, the final mixing amount should be determined depending on the application and required quality, and cannot be particularly limited.The present invention will be explained below with reference to examples, and methods for evaluating sliver shrinkage rate and sliver tensile strength in the examples. is as follows.

■ Sliver contraction rate After mixing the main fiber and binder clamp as uniformly as possible, pass it through a card to create a sliver. The sliver is subjected to relaxation heat treatment for 1° at a predetermined temperature, and the sliver shrinkage rate is determined from the length of the sliver before and after the treatment using the following formula.

M here t. is the length before heat treatment, and t is the length after heat treatment.

■ Sliver tensile strength■ The sliver obtained in ■ is pulled with chuck scissors at 1 or In intervals at a pulling speed of 20 cm/-, and the maximum load at cutting (f)'! ! 7 Read.

Separately, calculate the bond density of the sliver (i-L?/9000m, and take this as the apparent denier (De) of the sliver,
Calculate the slide/kuchi tensile strength using the following formula.

Examples 1-5. Comparative Examples 1-2 According to a conventional method, the molar ratio of terephthalic acid/isophthalic acid was 6.
0/40. A copolyester having a molar ratio of 1.4-butanediol/ethylene glycol of 97/3 was produced. The polyester has an intrinsic viscosity of o, s 5 dty measured in orthochlorophenol at 35°C.
y, the viscosity of the solution measured at 170°C was 16,900 voids. Next, the total spinning temperature of this polymer was 265°C.
The yarn was melt-spun through 1 gold having 420 holes to obtain an undrawn yarn with a medium twill of 9 deniers. The undrawn yarn was pulled together to form a tow, and stretched at a stretching temperature of 50°C to form 11 threads/2
After applying 5 holes of crimp, it was cut to a length of 51rrlfn. At this time, change the winding speed and stretching magnification to achieve elastic deformation finger 1! ! F# for binders with various (γe)
I made a fiber. This binder fiber had a melting point of 155°C and a glass transition point of 25°C. The obtained binder fibers and separately prepared 12 denier x 51 polyethylene terephthalate hollow fibers were thoroughly mixed at a weight ratio of 20:80, and then passed through a card to form a sliver. Also, at this time, the basis weight is x, IV4/lr? A laminated web was prepared and cut into 1 m x 1 m. The resulting sliver and the laminated web were subjected to relaxation heat treatment in an atmosphere of 170°C for 10 minutes, and the sliver tensile strength and web shrinkage # (presence or absence of "'wavy holes") were evaluated. Checked. Furthermore, γe
was measured in silicone oil at 175°C. The results obtained are shown in Table 1.

As is clear from Table 1, when γe exceeds 10, the sliver shrinkage rate becomes very large and the web shrinkage length becomes noticeable. Additionally, it can be seen that when γe becomes larger than 10, the rate of increase in the sliver shrinkage rate becomes extremely large.

Examples 6-7. Comparative Examples 3 to 4 The molar ratio of terephthalic acid/isophthalic acid was fixed at 60/40, and the molar ratio of 1,4-butanediol/ethylene glycol was varied to produce copolymerized polyesters having different glass transition points. These copolymerized polyesters are 35
The intrinsic viscosity measured in °C orthochlorophenol is 0.
70~0.75 dt/? within the range of 170℃
The melt viscosity measured at 11. OU O~13,000
It was within Boise's range. Next, these polymers were melt-spun at a spinning temperature of 265° C. through a nozzle with 420 holes, and wound at a speed of 600 m/m to obtain an undrawn yarn with a single filament fineness of 8 deniers. The undrawn yarns were pulled together to form a tow, and the stretching temperature was changed for each polymer to obtain a stretching ratio of 1.
．． The fibers were stretched twice, given 11 threads/25 threads of crimp, and then cut into a length of 51 runs to produce binder fibers with different glass transition points. These binder fibers and 12 denier x 51 denier polyethylene terephthalate hollow fibers were thoroughly mixed at a weight ratio of 20:80, and then passed through a card to make a sliver. At this time, the state of the fibers falling off to the bottom of the card was observed. The obtained sliver was subjected to relaxation heat treatment in an atmosphere of 170°C for 10 minutes,
Sliver shrinkage rate and sliver tensile strength were measured. In addition, γe was measured in silicone oil at 175°C.

The results obtained are shown in Table 2.

As is clear from Table 2, the glass transition point (Tg)
When the temperature exceeds 40° C., the binder fibers become brittle and often fall off from the card, resulting in a sliver with low tensile strength.

Claims (2)

[Claims] (1) Melting point is 200℃ or less, glass transition point is 40℃
A copolymerized polyester binder fiber having a single elastic deformation index of 10 or less. (2) Polyester fiber contains terephthalic acid component. Claim 1, which is a fiber made from a copolymerized polyester consisting of an isophthalic acid component, a 1,4-butanediol component, and a glycol component other than Borie-Tyl.
The copolymerized polyester binder fiber described in 2.