KR820000845B1 - Improvements in and realating to shaped articles from synthetic polymers - Google Patents

Abstract

The strength of melt-spun fibers obtained from polyesters forming anisotropic melts, esp. Polyesters prepd. from diphenols and arom. and(or) cycloaliph. dicarboxylic acids, is increased to 10g/denier by heat-treating the fiber at a temp. 20 below its flow temp. Films and bars of such polyesters are also strengthened by this treatment. For example, yarns from polymer I, obtained by polycondensing 2-chloro-1,-4-phenylene diacetate with 1, 4-cyclohexanedicarboxylic acid, were hung in an oven flushed continuously with N and subjected to the following temp./time(hr) cycles: 170≰/1, 230≰/1, 260≰/2, and 290≰/0.75.

Description

Improvement method of strength of molded article

This figure is the curve of the light intensity plotted against the temperature of polyester.

The present invention mainly relates to synthetic filaments, in particular, filaments produced by spinning a melt of a synthetic polymer and a method for improving the same, and a treatment method for improving the properties, particularly strength of such filaments and other molded articles, and Novel filaments and other molded articles obtained according to the above treatment methods which have useful properties (eg high strength) and which are particularly useful for other applications as industrial filaments (eg as reinforcing filaments for tires and also shaped articles). If the present invention is described in more detail with respect to filamentary articles, it will be appreciated that the same treatment can be carried out on other articles molded from suitable polymers.

The basic principle of producing fully synthetic linear polymers was discovered 40 years ago by W. H. Carothers, and then nylon filaments were industrially produced by melt spinning. The production of poly (ethylene terephthalate) filaments was first suggested by Whinfield and Dickson, after which industrial production of polyesters by melt spinning was developed.

The most convenient and economical way of forming filaments from synthetic polymers has been melt extrusion. This method is commonly referred to as “melt spinning” and is generally preferred over solution spinning. The use of solvents not only increases the cost and complexity of spinning, but also often adversely affects the tensile properties of the resulting filaments even after removing the solvent.

It is beneficial to obtain filaments of extremely high strength for some purpose.

Strength is the most important property for most industrial yarns, for example tire cords, but other properties are also important. By conventional stretching, the strength of nylon and poly (ethylene terephthalate) filaments could be improved.

The production of typical industrial polyesters suitable for use as tire cords is described in detail in Riggert's Modern Textiles, p 21-24, 1971.11.1. An important feature of the process described by Riggert is the use of high molecular weight poly (ethylene terephthalate), and also low levels of spun poly (ethylene terephthalate pre-orientation as it is spun, i.e. There is no need to keep it until the definitive is complete.

Therefore, the stretching tension on the filament is delayed until the solidifying poly (ethylene terephthalate-tate) filament is completely solidified, which then causes the solidified filament to be stretched orientated to increase its strength. For this reason, when high strength poly (ethylene terephthalate) filaments are required, high molecular weight poly (ethylene terephthalate) is spun into the heating zone to delay incubation.

Furthermore, in order to prevent decomposition at the high temperatures necessary to reduce the melt viscosity to enable extrusion, the polymer is first heated to a low temperature and then introduced into the spinning orifice through a special filter and the temperature (by converting mechanical energy into thermal energy) is desired. The temperature is raised to radiate from the spinning orifice to form a filament.

However, the formation of industrial filaments of strong nylon or poly (ethylene terephthalate) much larger than 10 g / denier has not yet been carried out industrially.

Relatively recently, very powerful aramid filaments have been formed on a limited commercial scale and these aramide filaments are extremely powerful and useful but must be spun from solution.

Thus, there has been a desire for a method for producing strong filaments from melt-spun synthetic polymers. It is important for this purpose that the melting point of the starting polymer should not be so high that dissolution of the melt is impossible.

It is also important to increase the flow motion of the filament sufficiently to prevent loss of strength during the operation and manufacturing process and therefore it is desirable to have a flow temperature of at least 200 ° C., preferably at least 250 ° C., for such filaments.

The term "flow temperature" is described in detail below.

A co-application with the present invention (inventor Schaefgen et al.) Has described a novel polyester which forms anisotropic melts, melt spinners oriented filaments therefrom and has particularly useful properties.

A notable structural property of the polyesters of the phase start application is that the molecular units in the polymer chain are predominantly cyclic structures (antiaromatic or cyclic aliphatic). Homo polyesters consisting of unsubstituted complete ring structures have too high melting points for general use, for example melt spinning. In order to obtain a useful anisotropic melt, it is thought that it is important to reduce the melting point to a desired and desired range according to a controlled method, which is composed mainly of rings of aromatic or cyclic aliphatic rings and has a rigidity of chain. .

Homocyclic polyester with complete ring structure.

(1) limiting substituents of ring structures, for example to chlorine bromine atoms and lower alkylies (preferably these) and / or

(2) limiting the copolymerization, ie limiting the copolymerization using two or more R ₁ and / or two R ₂ 's (which is often preferred) and / or

(3) introducing limited flexibility between the rings: for example, introducing flexibility by combining ethers and / or by aliphatic chains of limited length,

It is thought that the above-mentioned desired melting point requirement can be satisfied without losing the stiffness characteristics of the polyester which is such a ring-structured compound required for the anisotropy of the melt because it is modified by. Conventional melt-spun filaments of industrial, ie, high and strong polyester predominantly poly (ethylene terephthalate), in which polymer molecules are arranged irregularly straight, ie spun into unoriented filaments and require stretching to orient polyester molecules In contrast, the novel polyesters of the present invention can melt spun onto oriented filaments if they are sufficiently drawn as they exit the spinning orifice. In general, a radial elongation of 10 is sufficient. The ability to melt spun into oriented filaments derives from the nature of the anisotropic melt spun into filaments. Also, this anisotropy of the melt is due to the fact that the polyester molecules are in the form of elongated chains and the localized regions of the melt are oriented and the localized regions are oriented during extrusion and then appear to self-exist. Conventionally, in Roll and Hill's 1953 publication by Elsievir, "Rowl and Hill," From Synthetic Polymers, "Elsevier Pnblishing Co. 7953, the higher the molecular weight of the polymer, the higher the theoretical strength of the filament. It is described that the properties of conventional polyester filaments become the same level as the molecular weight increases. The use of extremely high molecular weight polyesters in filaments is impractical. This is because, as described in US Pat. No. 3,216,187, the melt viscosity of the polyester becomes high, making processing difficult, and this prior art tends to decompose the polyester at the high temperatures required to obtain an extrudable melt.

Therefore, in reality, if the molecular weight is exceeded, there is no practical use to obtain an improved strong polyester filament, but there is always an optimum molecular weight. It has previously been impossible to significantly increase strength by increasing the molecular weight of filamentary polymers after spinning conventional polyester filaments, ie poly (ethylene terephthalate) filaments, from melts of moderate melt viscosity and molecular weight. That is, after spinning, it is possible to increase the molecular weight of the poly (ethylene terephthalate) filament but not increase the strength significantly. It is believed that this heat treatment effect increases the folding of the molecular chain of poly (ethylene terephthalate) and increases the orientation. This is mentioned in Wilson, “Polymer” Vol. 277-282, 1974.5, May 15, 1794, “Polymers”, pages 15, pp. 277-282.

In contrast to this, however, according to the present invention, a polymer having a suitable melt viscosity can be spun from anisotropic melt to filament and heat treated to increase strength. The increase in strength can be achieved by increasing the molecular weight or increasing the degree of orientation. As the polymer correctly combines the flexibility and rigidity of the molecular chains to form anisotropic melts, the molecular weight increases when the fibers are heated immediately after spinning, instead of causing the folding of the molecular chains that is evident in poly (ethylene terephthalate). At the same time it is thought that the whole order and orientation is maintained or increased. It is important for the polyester to have a flow temperature of high temperature sufficient for such a heat treatment. It is also important to be able to polymerize at the same time as performing the heat treatment. This is because the end closure of the molecules (oxidation adversely affects the possibility of such heat treatment. The heat treatment of the filament should be carried out at as high a temperature as possible, i.e., close to the flow temperature, in practice at about 20 ° C below the flow temperature. When such heat treatment is performed on poly (ethylene terephthalate), the strength is sharply lowered, as evidenced by Wilson, The industrial heat treatment temperature of many preferred polyester starting materials is the melting temperature of poly (ethylene terephthalate). That is, it is estimated that it is in the range of 280-320 degreeC.

The method of improving the properties of the new polyester under heat treatment conditions is completely different from the treatment, heat setting or annealing that has been applied to melt-spun filaments such as nylon or poly (ethylene terephthalate) to remove the stress of the filaments. . In fact, it is surprising that such heat treatment can significantly improve the properties of filaments spun from anisotropic melts.

It was later discovered that synthetic polymers other than this novel polyester can also form anisotropic melts, melt-spin filaments from these melts, and improve the properties of the filaments by heat treatment after extrusion. Furthermore, it is believed that this is a property of the polymer itself in the form of shaped articles rather than the fact that it is melt spun. Therefore, according to the present invention, the strength of various molded articles can be improved by heat-treating a molten molded article molded from a synthetic linear polymer capable of forming an anisotropic melt and improving its strength by 50% or more. Preferably, the polymer has a flow temperature of 200 ° C. or more, in particular 250 ° C. or more, and this flow temperature is measured for the starting material to be heat-treated as described later, and the heat-treated filament is about 50 ° C. higher than the starting polymer. It can be seen that it has a flow temperature. Of course, the present invention is completely different from U.S. Pat.Nos. 3,778,410 or 3,804,805, and the above-mentioned patents are prepared by reacting the starting polyester and acyloxy aromatic carboxylic acid to prepare the final copolyester, and poly (ethylene terephthalate) and A copolyester prepared from acyloxinebenzoic acid is suggested, and the conventional melt spinning drafting heat setting of fibers made of such copolyester and the treatment by techniques well known in the art (Section 7 of US Pat. No. 778,410) Second verse from last).

In Examples 1 and 2, it can be seen that the heat setting treatment method does not increase the fiber strength very much. Furthermore according to the present invention such copolyesters, for example those derived from the residues of 60 mol% P-acetoxybenzoic acid and the residues of 40 mol% poly (ethylene terephthalate) described in Example 1, and other The anisotropic melt can be adjusted from a ratio containing, for example, 67 mole% of the residues of P-acetoxybenzoic acid, and the oriented filaments could be melt spun from such anisotropic melt, but such filaments are suggested in the present invention. In contrast to filaments, the strength could not be increased effectively even with heat treatment. It is not clear why these prior art filaments are not suitable materials for the heat treatment according to the invention, but one reason is that

This seems to be due to the large amount of poly (ethylene terephthalate) residues containing a large amount of ethylene bonds in the repeating unit. This repeating unit contains a chain of six non-reducing groups and does not consist of a major proportion of rings, so is typical of poly (ethylene terephthalate) in contrast to the repeating units of the starting polyester suggested in the examples of the present invention. It is expected to have sufficient flexibility, indicating overlap of the chain reported by Wilson.

The repeating unit of the polyester suggested in the embodiment of the present invention is as follows.

The longest chain between rings in these constructs contains four acyclic chain atoms and appears at position 4A of the copolymer. That is, not all repeating units contain such flexible linkages. Suitable starting polyesters for the heat treatment according to the invention contain four non-chain atoms between the rings. Some acyclics are less flexible than others and the maximum of chain atoms varies depending on the flexibility and robustness of the molecule. The repeating unit consists mainly of an annular structure.

It is also important that the starting polymers can be polymerized again below the flow temperature, in which polymers prepared by two-step fragmentation / building from poly (ethylene terephthalate) and acyloxy aromatic carboxylic acids can be polymerized again under these conditions. It seems to be impossible. Preferred polymer starting materials are prepared by polycondensation of dihydric phenols with aromatic and / or cyclic aliphatic dicarboxylic acids to heat treatment before end-capping occurs by oxidation. If necessary, as in Example 10, the acyloxy aromatic carboxylic acid is polycondensed into a dihydric phenol and an aromatic and / or cyclic aliphatic dicarboxylic acid to produce a copolyester, which is molded and heat treated according to the method of the present invention to increase its strength. Can improve. Certain methods used to prepare conventional polymers may also take into account the inability to reinforce the filaments under the heat treatment conditions used in accordance with the present invention, e.g. this method contains poly (ethylene terephthalate) units in its chain. It will also be appreciated that the fact that it produces a polymer or that this method produces aliphatic hydroxy end groups.

The exact conditions of the heat treatment vary depending on the particular polymer to be treated and are described in particular in the following examples with regard to polyester filaments spun from anisotropic melts. As the temperature increases within a certain range, the heat treatment proceeds more rapidly and therefore should not be carried out at too high a temperature. That is, it is difficult to rewind because of entanglement of the filaments. On the other hand, a problem occurs at a slightly lower temperature due to the sticking of the filament, but preliminary coating of the filament in a thin layer with an inert material such as pulverized talcum, graphite or aluminum is possible even at such a low temperature.

In this way useful results are obtained as in Examples 4D and 4G. Continuous purge with nitrogen is extremely important. The effluent of nitrogen will contain a polymerization byproduct such as acetic acid from the starting material 1,4-phenylene diacetate. Therefore, since the heat treatment temperature is lower than the flow temperature, the heat treatment can continue the continuous polymerization of the polymer molecules without affecting the shape of the treated material. By removing such a polymerization byproduct from the polymer, it is possible to perform continuous polymerization during the heat treatment. Other gases that are inert to the dipolymer under heat treatment may be used instead of nitrogen, and heating may be performed under reduced pressure to remove by-products. The determination of the time at which the heat treatment should be stopped is determined by examining the depletion of gases generated by carbon dioxide or decomposition products. Conventional polyesters tended to shrink significantly when heated to a temperature lower than the flow temperature under the same conditions, but the filaments of the present invention do not change in length during heat treatment. The filaments are preferably heat treated under relaxed conditions. In other words, the filament should not be treated under excessive tension. In fact, it is preferable to heat-treat the filament wound on the bobbin yarn. As in the embodiments described below, it is desirable that the filament be tensioned under slight tension and that it can be slightly expanded or shrunk during the heat treatment. Slightly lower than the flow temperature, the filament is cut by heat treatment with excessive tension under the temperature of about 20˚C. In practice, however, heat treatment is carried out under very little tension, and the maximum tension should be limited by the heat treatment conditions, eg the strength of the filament over temperature and / or time. Yarn can be strengthened by heat treatment under slight tension (typically less than 1 g / denier), but there is little benefit from increasing strength.

The filaments should be oriented prior to heat treatment, ie have an X-ray orientation angle of less than about 65 ° C. Filaments that already have a strength of at least 1 g / denier or more are generally preferred.

An important feature of the present invention is that the filament of the polymer can be melt spun and then heat treated to increase the strength above 10 g / denier. The filaments obtained are preferred products of the invention and particularly those of polymers having a significantly high strength, ie at least 15 g / denier and preferably at least 20 g / denier or more.

It should be appreciated that heat treatment often increases modulus as well as filament strength.

Preferred products of the invention are filaments having a modulus of at least 100 g / denier, in particular at least 300 g / denier comparable to glass.

The method of the present invention is described in detail in the following examples. In order to simplify and convenience this Example, it has shown in table form. Most of the polymers heat-treated in this embodiment are novel polyesters, which can be seen in the examples of the same application (inventor Schaefgen, etc.), which will be described in detail.

Additional polymers treated in the following examples are as follows.

Example 1F Homoprimer prepared from chloro substituted 1,4-phenylene diacetate and ethylenedioxy-bis (2,6-dimethyl-4-benzoic acid).

Examples 7B and 7C: residues of mono- and di-chloro-substituted 1,4-phenylene diols and residues of p-carboxyphenoxyacetic acid (7B) and methylene-dioxy-4,4′-dibenzoic acid Copolyester containing the residue of (7C).

이며, 대부분이 에스테르기로 구성된, 폴리에스테르로 수득한다.Example 7B shows excellent results, the result being that the dicarboxylic acid, one aromatic carboxyl group and one aliphatic carboxyl group are separated from the ring by a short chain (-OCH _2- ), ie the most between the rings in the dipolymer. Long chains

Obtained as polyester, mostly composed of ester groups.

Thiol / oxygen esters containing residues derived from p-mercaptophenol, oxy-bis (4-benzoic acid) and terephthalic acid of Example 8D.

Example 10 shows a coplier containing 82 mole% ρ-oxybenzoyl and 18 mole% oxy-bis (1,4-phenyleneoxy) and terephthaloyl, wherein the copolymer is an acyloxy aromatic as described above. One example of a copolymer ester derived from the reaction of a carboxylic acid with a divalent phenol derivative and an aromatic and / or cycloaliphatic dicarboxylic acid. Polymerization conditions are conventional as described above and an important point of the present invention lies in the surprising feature of shaped materials, in particular oriented filaments, which can be melted and anisotropic and obtained from polymer melts, usually within the useful range.

Melt spinning conditions are also common but the orientation fibers must be spun by spin stretching the resulting filaments at least 10 times as in all examples.

The R ₁ groups of Example 1 are chlorine-substituted (A and B), bromine-substituted (C) and methyl-substituted (D and E) 1,4-phenylene rings and the corresponding chlorine-, bromine- and methyl-substituted 1,4 It is derived by reacting with an equivalent dicarboxylic acid giving the R ₂ group in equivalent molar ratio with methylene diacetate.

The reactive components react efficiently in a conventional manner, ie, in a polymer melt tube with a side arm (branch), an extruded tube microadapter of nitrogen or an inert gas, a stirrer, a distillate collection tube and the like. The polymerization conditions were as described in Example 1A, and the reactant and contents were first stirred by heating at 283 ° C. for 1 hour (60 minutes) in the presence of anhydrous sodium acetate (catalyst), and distilled acetic acid by-product was 0.2mmHg, After heating for 10 minutes at 283˚C and finally heating at 305˚C for 25 minutes at 0.2mmHg, the resulting anisotropic melt is cooled and the polymer is isolated to confirm that the intrinsic viscosity is 3.4 (solvent 2). The reaction is stirred with a stirrer, in particular in the initial stage, by passing through nitrogen or an inert gas and passing by-products distilled under reduced pressure. A catalyst is not usually required but can be used in Examples 5D (antimony trioxide) and 8D and 10A (sodium acetate).

For "polymerization", the given temperature (temperature displacement) and heating time are initially made at 283 ° C for 60 minutes, for example for Example 1A, and are only mentioned when the pressure differs from atmospheric pressure. The polymer having intrinsic viscosity (ninh) is described and the measurement for the filament is indicated as (F). The method and solvent are as described below, but the indication “insol” indicates that the polymer is not soluble in the solvent, and therefore the inherent viscosity cannot be measured but can be dissolved in another solvent to make a solution. Heat treatment is carried out as follows.

(a) a yarn of one tar was suspended in an oven treated with a continuous stream of nitrogen to heat the oven and the sample to a constant degree and time,

(b) The yarn is wound in a through bobbin, placed in an oven and treated as in (a) above. Bobbins are coated with ceramics under low stress to give a flexible heat resistant surface.

(c) The yarn is loosely loaded in a perforated metal basket in an oven and treated as described in (a) above or loaded into a glass tube to continuously pass nitrogen through the filament to keep the glass tube at a constant temperature and time period. Heat.

The cycle of temperature and time is shown in the table. In Example 1A, the oven and the sample were heated under nitrogen atmosphere for 1 hour at 170 ° C, then 1 hour at 230 ° C, then 2 hours at 260 ° C, and finally at 290 ° C for 45 minutes.

In general, temperature changes are so rapid that ovens and samples also need to maintain electricity at a constant temperature over a period of time. If the temperature change is slow, display as follows.

As in Example 1B (25-310 / 0.7), the arrow indicates that the change in temperature is not relatively fast, and as in Example 5C (150-160 / 1.5), the words “to” indicate a temperature within the stated range. The dash (-) table means that the temperature changes slowly over the first 10 to 30 minutes, as in Example 5A (235-265 / 1.5), and the rest of the period is maintained at a higher temperature.

The oven is left to cool from time to time as in Example 3A and then heated again.

Example 1

Example 2

EXAMPLE 2 CONTINUED

Example 3

Example 4

Example 5

Example 6

Example 7

Example 8

Example 9

Example 10

Preferred combinations disclosed in the present specification are represented by the following general formula.

는 방향족 또는 환상 지방족 디카복실산에서의 2가의 라디칼이며 다음과 같은 것이 포함된다.-OR ₁ -O- in this general formula is a divalent radical in the dihydric phenol,

Is a divalent radical in an aromatic or cyclic aliphatic dicarboxylic acid and includes the following.

A) at least about 95 mole% of the R ₁ group is chloro substituted 1,4-phenylene, and at least about 95 mole% of the R ₂ group is trans-1,4-cyclohexylene (e.g., poly (chloro-1,4-phenylene Lance-1,4-cyclohexane dicarboxylate)]

B) R 2 is a bis (4-carboxyphenyl) ether and R ₁ is selected from chloro and methyl substituted 1,4-phenylene or less preferred, but is bromo-1,4-phenylene, R ₁ And up to 20 mole percent and 10 mole percent of the total units of R ₄ , ie up to 20 mole percent of R ₁ are 1,4-phenylene, dichloro-1,4-phenylene, 4,4-biphenyl Ene, oxy-1,4-diphenylene, thio-1,4-diphenylene, or 3,3 ', 5,5'-tetramethyl-4,4'-biphenylene and / or Up to 20 mole% R ₂ is 1,4-phenylene, 1,4-cyclohexylene, 2,6-naphthalene, 4,4′-biphenylene, or ethylene dioxy di-1,4-phenylene Or, but not preferred, 1,3-phenylene, chloro- and / or bromo substituted 1,4-phenylene,

The) R ₂ is 20 to 80 mol% of bis (4-phenylene-oxy) ethylene and from 80 to 20 mole percent 1,4-phenylene, 1,4-cyclohexylene and 4,4'-biphenylene And R ₁ is selected from 20 to 100 mol% of methyl and chloro substituted 1,4-phenylene and up to 80 mol% of 1,4-phenylene,

D) in the range of copolymers shown in Examples 2 and 3, wherein R ₁ is from 85 to 60 mol% [preferably 70 mol%] of chloro or methyl substituted 1,4-phenylene and 15 to 40 mol % [Preferably 30 mol%] of oxy-bis (1,4-phenylene) ether, R ₂ is 1,4-phenylene, and

E) R ₂ is from 20 to 80 mole% of 1,4-phenylene and from 80 to 20 mole% of 4,4′-biphenylene and / or 2,6-naphthalene and / or 1,4-cyclohexylene Hexylene / or oxy-bis (1,4-phenylene), R ₁ on chloro- or methyl substituted 1,4-phenylene, or less preferred but bromo substituted-1,4-phenylene.

It is clear that many modifications are possible from the many types of polymers exemplified, and that polymers other than polyester, such as thiol esters, can be treated according to the invention. From an industrial point of view, it may seem desirable to use relatively simple or inexpensive reaction components in comparatively simple combinations, but it should be appreciated that the present invention is based on the essential invention and is not disclosed precisely herein. It is anticipated that certain properties can be heat treated to improve their properties.

The followings other than the filaments are also treated by the present invention.

A: An anisotropic melt of poly (chloro-1,4-phenylene trans-1,4-cyclohexane-dicarboxylate) was subjected to a stepping extruder to insert slots having a diameter of 3ins × 3mils (8cm × 0.08mm). By melt extrusion on the casting drum at 303 to 310 ° C through quenching and winding in water to produce a high-strength film having an orientation angle of about 20 °. After cooling for 3 hours at 170˚C in nitrogen, 16 hours at 230˚C, 22 hours at 260˚C, 7 hours at 285 ° C and 64 hours at 260 ° C, the cooled film is 0.04 in thickness and tensile Strength / Elongation / Module 110,000 psi / 3.5 2,950,000 psi (7,700 kg / cm 2 /3.5%/207,000 kg / cm 2).

B: The bar formed from the polyester of the present invention showed that its rigidity was very excellent as measured by the stiffness measured by (FM) and the Izod impact strength (n ¹ ) of the brass part. . For example, a bar of poly (chloro-1,4-phenylene 1,4-cyclohexane-dicarboxylate) has 580,000 psi (41,000 kg / sq · cm 2) of FM and 2.2 ft lb / in (12 kg.cm/ It showed notchwi n ¹ of the ㎝).

These bars are heat treated when the polymerization byproducts are removed. Its by-products have problems when the molded article is a higher quality product than a relatively thin filament or film. Internal heating, such as internal heating by a dielectric device, may first polymerize the surface of the article to avoid the formation of a coating that prevents the removal of by-products. The bar of poly (chloro-1,4-phenylene terephthalate / 2,6-naphthalate) (70/30) can be heat treated to increase the Izod impact strength of the brass portion by about 250%.

Properties and characteristics indicated herein were measured as follows.

Optical Anisotropy-TOT (Thermo-optic Test)

Translucent optically anisotropic materials are known to transmit polarized light in optical systems with cross polarizers, but the projection of light is known to be zero for isotropic materials under the same conditions. The following thermal-optical test (TOT) takes advantage of this point in references I.kirshenbaum, R. B. Issasson and W. C. Feist. Polymers Letters 2,897-901 (1964) have been used to clarify the anisotropic polyester melts according to the present invention with similar devices. This method is especially designed for testing polyesters and also requires modifications to other aggregates. The thermal-optical test (TOT) requires a flat microscope to have a non-uniformity of absorptivity and to show photosensitization by sufficiently high cross (90 ° C.) polarizers to give the background transmission specified below.

Leitz Dialux-pol microscope is used for the measurement for reporting. The microscope has a Polaroid polarizer, binocalar exepieces and heating means. The detector is attached to the top of the microscope barrel. The microscope has a magnification of 32 times and has a long-distance object lens and a Red I plate (used only for visual observation with crossed polarizers inserted at an angle of 45 ° to each polarizer). Light from the light source is passed through a polarizer, a sample on the heating means, and an analyzer to a photodetector or eyepiece. The image appearing on the eyepiece is transferred to the photodetector by the slide. The heating means to be used can heat up to 500 degreeC. Use a “Unitron” model MHS vacuum heating unit (Cinitron Instrument Co. 66, Needham St. Newhton Highlands Massach Usetls O2161). The signal of the photodetector is amplified and sent to the Y side of the X-Y recorder.

The response of the system to the intensity of light shall be in red and the measurement error shall be within ± 1 mm on the recording sheet. The heating means has two thermocouples. One is connected to the X-side of the X-Y recorder to record the temperature of the heating means, and the other is connected to the programmed temperature controller.

This microscope focuses the microscope on a sample of the polymer prepared and placed as described below (as a replacement polarizer). The sample is removed from the optical path, not the coverslip.

Full scale refraction on the Y-axis of the XY recorder (18 cm on the chart used) by removing the microscope's polaroid divider from the optical path, moving the slide to transfer the image to the photodetector and adjusting the entire system This corresponds to 36% of this photometer signal. Background transmittance is recorded (without sample) using crossed (90 °) polarizers and carverslips in the optical path. Background projection in the system used should not be affected by temperature and should be less than about 0.5 cm on the chart.

The sample may be finely cut to a thickness of 5 탆 with a diamond knife from a well-assembled chip of a pure polymer (for example, manufactured in Example) fixed in an epoxy resin.

Although not preferred, a particularly useful method for low molecular weight materials that break up when cutting a microtomed section is to heat a fine polymer sample on a hotplate on a carver slip on a microscope slide.

The temperature of the hot plate (about 10 ° C. higher than the flow temperature of the first polymer) is raised to allow the polymer to fuse directly into a thin film that is essentially the same thickness as the thickness of the flakes, i.

The sample is pressed flat between the coverslips. Remove one cover slip and place the sample on the remaining carver slip on the heating means. Glass down. The background transmission is measured and the sample is positioned so that almost all light rays blocked by the photometer pass through the sample.

The intensity and temperature of the light is recorded on the X-Y recorder using a sample between the cross (90 °) polarizers in a nitrogen atmosphere, raising the temperature from 25 ° C. to 450 ° C. at a programmed rate of about 14 ° C./min. The temperature of the sample can be found from the recorded temperature by using an appropriate calibration curve.

The test is described again with reference to the accompanying drawings. In this figure, the light intensity curve plotted against the temperature of poly (ethylene terephthalate) is shown.

This polyethylene terephthalate is a polyester (poly (chloro-1,4-phenylene trans-1,4-cyclohexanedicarboxylate)) which is a polyester capable of forming an isotropic melt (curve A) and heat treating it according to the invention. Forms an anisotropic melt (curve B). When placed between polarizers that intersect (90 °) the isotropic melt (the sample must be fully molten), the light intensity passing through the spectrometer essentially crosses the light intensity of the background transmission (90 degrees rather than carverslips). Obtained outside the field of view of one polarizer). As the melt is produced, the intensity of light transmission decreases from high intensity as in curve A of the figure illustrating the intensity of (1) the background transmission, or (2) the strength of the poly (ethylene terephthalate) producing the isotropic melt. Or

When a sample of polyester which can be heat treated according to the present invention is heated above the flow temperature of the sample between intersecting polarizers, the intensity of the transmitted light appearing on the recorder chart is at least twice the height of the background transmission curve. It is believed that the polyesters of the present invention form an anisotropic melt since at least 0.5 cm becomes larger. As the melt forms, the light transmission curve (height) is (1) at least 0.5 cm greater than the background transmission, and also its value is at least doubled, or (2) at least doubled. Curve B in the figure illustrates the strength curve in the form (2) mentioned and commonly obtained for a system producing an anisotropic melt according to the invention.

Polyesters that can be heat treated according to the invention often exhibit optical anisotropy within all temperature ranges tested, i.e. in the range from the polymer's flow temperature to the polymer's decomposition temperature, or the highest test temperature (450 ° C).

However, in some types of polymers, when the melt begins to pyrolyze, some of the melt may become isotropic.

In another type of polyester the melt's properties completely change from anisotropic to isotropic with increasing temperature.

η (intrinsic viscosity)

This is measured according to the method described in US Pat. No. 3,827,998 using the following solvent system (volume ratio).

1) 60% trifluoroacetic acid / 40% methylene chloride

(1B) 60% trifluoroacetic acid / 70% methylene chloride

2) 1,3-dichloro-1,1,3,3-tetrafluoroacetone hydrate

3) 50% solvent (2) / 50% methylene perchlorate

4) P-Phenol Chloride

5) 15% trifluoroacetic acid / 35% methylene chloride / 25% solvent (2) / 25% perchlorate

6) 50% Solvent (5) / 50% Solvent (4)

The range of suitable intrinsic viscosities largely depends on the flammability of the polymer molecules, which relates only to soluble polymers.

Polymers with a viscosity as low as 0.3 are useful (eg for coating). As the soluble polymer, the intrinsic viscosity should generally be 4.0 or less on the part of the operation. As is known, particularly high melt viscosity causes many operational problems such as making melt spinning very difficult. It has been found that insoluble filaments that flow within the flow temperature range of the polymer are industrially useful.

Flow temperature

This refers to the temperature at which the polymer flows. This flow temperature is evident by the sharp end of a small piece of polymer as the melt viscosity increases or by the rounded cut fibers. Its flow temperature is determined by visually observing the sample on the coverslip located between the heating means plates intersected (90 °) polarizers described in the TOT operation. Appropriate heating rates typically use a rate of about 50 ° C./minute, which is faster than 14 ° C./minute but in some cases resulting from polymerization at rapid rate.

The flow temperature of any particular sample will also depend on its treatment. For example, it continues to have a different flow temperature from the molded article and the polymer used to mold the article, and the stepwise heating typically raises the flow temperature to produce a heat treatment temperature higher than the initial flow temperature as indicated in some embodiments. You can increase it gradually.

For processability, the polymer will flow at a temperature lower than the temperature at which rapid decomposition occurs, otherwise plasticizers, solvents or other techniques will be necessary to form the desired molded article. Certain polymers may be processed to temperatures as high as 450 ° C., but for example the flow temperature is preferably in the range of 400 ° C. or lower, such as 200 to 370 ° C., in particular 250 to 350 ° C.

The radial elongation is the ratio of the speed of the melt passing through the large spinneret (measured at the time of winding) of the extruded yarn, and the latter speed is the volume divided by the volume of the melt extruded per minute for each minute).

Properties of Filament:

This property is described for both the filament immediately after spinning and the heat-treated filament. Tensile properties are measured as in US Pat. No. 3,827,998, where "Y" or "F" represents either yarn of multifilament or one filament. OA ° (arc °) is indicated in the US Patent No. 3,671,542 by indicating the orientation angle and [20 specificarc] and measured according to the method (2).

Claims (1)

A synthetic linear polymer capable of forming an anisotropic melt, comprising a filament molded article formed from a polyester composed of one or two or more divalent phenol residues and one or two or more aromatic or cyclic aliphatic dicarboxylic acid residues. A method of improving the strength of a molded article, characterized in that at least 50% of its strength is improved by heat treatment at a temperature within 20 ° C. below the flow temperature of the filament so that the strength exceeds 10 g / denier.

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