DE2115297A1 - Process for making molded articles from polycaprolactam - Google Patents

Description

Process for making molded articles from polycaprolactam

The invention relates to a "method of making shaped articles from polycaprolactam, and more particularly to a method of making shaped articles such as fibers, films or molding. The method relates to melt-molding polycaprolactam in the presence of a small amount of water. The polycaprolactam becomes prepared by polymerization of caprolactam in the presence of an alkaline catalyst and an activator at a temperature below the melting point of the polycaprolactam. This product contains little or no wasserlösliciies material, such as monomeric and oligomeric compounds of. üaprolactam, hereinafter, the term monomers together m ^ n be taken.

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Polycaprolactam has long been used according to various processes manufactured. .

For example:

1. Caprolactam is polymerized in the presence of water.

2. Anhydrous or substantially anhydrous caprolactam " is in the presence of an alkaline catalyst such as a Alkali, an alkaline earth or a "compound" thereof

* polymerized.

3. An alkaline catalyst is used to polymerize caprolactam in combination with an activator such as acyllactam, used.

The method No. 1 requires a long reaction time and that The product therefore contains a considerable amount of monomers, in the amount of about 10% by weight.

The ITr. 2 can be done in less time and leads to a product with a higher degree of polymerisation, b but this product also contains monomer in an amount of about 10% by weight.

Process No. 3 can be carried out at a temperature below Melting point of the polymer formed can be carried out in a shorter time than the method No. 2, and the method contains fewer monomers, i.e. 2 to 5% by weight. Especially when the Polymerization is carried out at about 150 ° C, is the Monomer content about 2% by weight.

In order to produce molded articles of good quality, a polycaprolactam produced by Process No. 1 or 2 should be subjected to a cleaning pretreatment to remove the monomer; for example an extraction with

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that of the water. The low monomer content of the after, the process No. 3 manufactured polycaprolactams allows use this polymer for the manufacture of molded articles directly.

It has been found, however, that such a product is among the Conditions of the melting process rapidly decomposes, and that the amount of the monomer up to about 10% by weight within a few Minutes increases. In this way goes the benefit of the application of the low-temperature process is lost again.

It has now been found that in the presence of an alkaline Catalyst and an activator at a temperature below Polycaprolactam formed at its melting point can be subjected to a molding process without formation of monomers occurs when water is added to the polycaprolactam. .

This is surprising because when using a polycaprolactam, that with the addition of water or an alkaline compound obtained as a catalyst and whose monomer content is reduced by .Reinigung, for an ochmelzverfahren in the presence In turn, the monomer content of water increases.

It is. it is not intended that the invention apply to any Theoretical explanation is limited, but it is believed that the active group of the catalyst is within the polymer reacts with the water, thus preventing the polymer from breaking down hinders.

The amount of water added to the polymer is small and generally ranges between 0.1 and Ίο moles for one Moles of alkaline catalyst present in the polymer; preferably between o, j? and 5 moles. If the amount of water is low

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is lower than the lower limit, decomposition of the polymer can occur cannot be effectively prevented. The upper limit of the water to be added to the polymer is unlimited, unless the Molding process is adversely affected. If more than Io Mole water, calculated on the alkaline catalyst are present, the molding process can consequently be carried out step-by-step, using a vacuum forming apparatus, with the water is stopped breastfeeding.

Any method of adding water to the polymer can be used be provided that the water is not is only present on the surface, but penetrates into the polymer. For example, if the polymer is finely divided Shape is present, for example with a particle size of less than 2 mm, a certain amount of water is added or the polymer is conditioned in a humid atmosphere. As far as the polymer in the form of rods, sheets, blocks or the like, it is immersed in water or a steam machine subjected to steam.

Polycaprolactam can be made from caprolactam by using an alkaline one Catalyst and an activator are prepared, which are well known in the polymerization art. the Polymerization is preferably carried out at a temperature of 12o 1 & o ° C carried out.

Examples of alkaline catalysts which can be used in the process of the invention are alkalis such as lithium, sodium and potassium, alkaline earths such as magnesium, calcium and barium and compounds thereof including caprolaetam salts, hydroxides, hydrates, carbonates and alkoxides. The catalyst can be used in amounts of _ ^ i- ^s '' ^: ^ 500 moles per mole

5 ο -

Caprolactam may be applied .-- As examples of activators seisn acylates, esters, isocyanates, urea and urethane compounds called.

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According to the invention, it is possible to produce molded articles by the melt process from polycaprolactam which have a have lower monomer content, without use some special expensive equipment.

The invention shall be described in more detail with reference to the following Examples are explained, but it should be noted that the examples are only given for "clarification, and the essence · not "limit the invention.

The monomer content given in the examples is determined in such a way that particles of the polymer which had a particle size of less than Λ mm were immersed in boiling water for 2 hours, the dry weight of the particles being measured before and after the immersion.

example 1

A test tube 20 mm in diameter was used with 0.1 mole of caprolactarn, one MiHimol of sodium caprolactam and 1 millimole H-acetylcaprolactam charged. The polymerization took place in a nitrogen atmosphere at 155 G for one hour. That resulting polymers contained 2.5% by weight monomer.

Some of the polymer turned into particles less than 1 mm Grind diameter. Then the ground particles were calculated based on the molecular ratio of the sodium present, three times the amount of water / water added and the polymer under nitrogen atmosphere melted at 25o ° C for one hour, Each polymer "contained 2.5 G-exir .-> o monomer.

For comparison purposes, the rest of the polymer was melted under the same conditions but without the addition of water. In this üj'slle, -5 wt were 1o - ^c / o monomer found in the polymer.. (■

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Example 2 . - - ■

The same procedure as in Example 1 was repeated with the difference is that the temperature was set to 16o G. The polymer obtained contained 3% by weight of monomer.

A portion of the polymer was melted under a nitrogen atmosphere at 255 ° C. for one hour together with an amount of water which corresponded to five times the sodium content of the polymer. The monomer tightness in the treated polymer was still 3 _? o ° / o.

The Best was treated under the same conditions but without the addition of water. The monomer content increased to 11.5 %

Example 3

In a test tube with a diameter of 20 mm, 0.1 mole of caprolaetam _s, 1 millimole of matrium caprolactam and 1 millimole of IT-acetylcaprolactam were placed. under a nitrogen atmosphere for one hour at 15o ° 0 ₂ heated to the PoI ^

mers contained 2 _S 7 % monomer,

at 15o ° ö ₂ heated to effect the polymerization., The poly-

* Part of the polymer was immersed in boiling water for 1 hour and the excess water present on the surface was wiped off Melting the polymer under a nitrogen atmosphere at 255 G for one hour, the polymer contained 4% by weight of monomer = The polymer melted under the same conditions without the addition of water, however, contained 11% monomer

4-

In a pan with a diameter of 4 cm, 10 moles of caprolactam in the presence of ₉ 1 mole of sodium caprolactam and O ₂ I mole of ST-Ace-

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tylca ^ rolactam under a nitrogen atmosphere for one hour at 160 ° C polymerized. The monomer content in the polymer was found to be six 2.5 wt. The particles obtained from the polymer obtained, having a particle size of less than 2 mm, were conditioned for 20 minutes in an atmosphere at 20 ° C. and 60% relative humidity in order to adjust the water content to 0.1% by weight melt-spun using an intruder at 270 ° C. The residence time was 20 minutes. A fiber with 2.8 % monomer content was obtained.

Unconditioned polymer was made into fibers under the same conditions. The fiber contained 1o, 5 wt -.% Monomer. . - ""

Example 5

A test tube 20 mm in diameter was charged with 0.2 moles of caprolactam, 2 millimoles of sodium caprolactam and 2 millimoles of ji-acetylcaprolactam. The polymerization took place for one hour at 16 ° C. under a nitrogen atmosphere. The polymer obtained contained 2.8 ^c / o monomer, it was immersed in boiling water for one hour and then melted at 255 G for one hour while maintaining it under a pressure of 20 mm Hg. The polymer contained 30 % monomer.

Example 6

In a test tube 10 mm in diameter, 0.1 mole of caprolactam was polymerized in the presence of 1 millimole of sodium caprolactam and 0.5 millimoles of triethylene glycol dibenzoate under a nitrogen atmosphere for one hour at 17 ° C., a polymer containing 3% by weight of monomer was obtained. The polymer was immersed in boiling water for one hour and melted at 255 ° G under pressure of Jo mi Hg for one hour. The polymer obtained contained 3 % monomer. _ _{R _}

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Example 7 · ■

Polymerization of 0.1 mol of caprolactam in the presence of 1 millimole of liatrium caprolactam and 0.5 millimoles of methylenebisphenyl isocyanate at 150 G for one hour under a nitrogen atmosphere gave a polycaprolactam containing 0.1% by weight of monomer. The polymer in the form of ponds, the size of which was less than Λ mm, was mixed with 10 mg of water and melted under nitrogen at 255 ° C. for one hour. The monomer content did not change, it was still even after the melting treatment 3 ^c / o.

The following tests were carried out for comparison.

Example 8 ". - -

In a test tube with a diameter of 20 mm, 0.1 mole of caprolactam, 1 millimole of sodium caprolactam and N-acetylcaprolactam were heated to 25 ° C for 20 minutes under a nitrogen atmosphere, with a polycaprolactam containing 10.5% by weight of monomer was obtained-. The polymer was ground to particles 2 mm in size and treated with boiling water for 30 minutes in order to reduce the monomer content to 2.1 ^c / o . The polymer was dried in vacuo at 100 ° C. for five hours. In the bath result, the polymer contained opo5 ^c / ° water. A portion of the polymer was melted at 255 g for one hour. The monomer content of the product rose to 5.3 "/ <> · The product was mixed with 0.3% by weight of water and heated under the same conditions. The monomer content rose to 5.5- # ...

Example 9 -

Gaprolactam was in the presence of o, 3 wt -% polymerized water 2o hours.. The polymer in chip form of 2 mm in size, with a content of 1o, 3% of the monomers, was subjected to extraction treatment with boiling water for one hour, to reduce the monomer content to 2.5%. The polymer

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was dried in vacuo at 100 ° G for five hours in order to reduce the water content to 0.04 % . Part of the polymer was melted at 255 ° G for one hour under nitrogen. The monomer content increased to 5 ₅ 4 %.

iJer ü-ös-t was mixed with 0.2% water and subjected to a heat treatment under the same conditions. The polymer obtained also contained 5-5% monomer.

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Claims (1)

P_a_t_e_n_t_a_n_s_p__r_ü_o_h._e 1. Process for making molded articles Polycaprolactam, characterized in that the polycaprolactam is deformed in the presence of a small amount of water, this polycaprolactam being polymerized of caprolactam in the presence of an alkaline "Catalyst and an activator at one temperature is produced below the melting point of the caprolactam formed. 2. A method for producing molded articles from polycaprolactam according to claim 1, characterized in that that the water in. Amounts of 0.1 to 10 moles to 1 mole of the alkaline catalyst is present. 3ο method according to claims 1 or 2, characterized j that the P-olycaprolactam to be moistened the Form of small particles with a particle size of less than 2 mm. having. . 4o method according to any one of the preceding claims, characterized characterized in that the polymer is moistened by immersing it in ■ Hasser » Method according to one of Claims 1 to 4, characterized in that that the polymer is moistened by steaming » ο Process according to one of the preceding claims _9, characterized in that as the alkaline catalyst alkali, alkaline earth or a caprolactam as _s a hydroside ₉ a hydride j an carbonate or an alkali metal or alkali ■ - 11 10 8 8 4 4/1791 Alkaline earth is used. 7 · Method according to one of the preceding claims, characterized characterized in that the alkaline catalyst consists of sodium caprolactam consists. 6. The method according to any one of the preceding claims, characterized in that an acylate, an ester, an isocyanate, urea or urethane compound is used. 9. The method according to any one of claims 1 to 8, characterized in that that as an activator N-acetylcaprolactam, Triethyl englycoldibeiizo at or methanediphenyl diisocyanate used iirden. 10. The method according to any one of the preceding claims, characterized in that the polycaprolactam by polymerization of Gaprolactam at temperatures between 12o C and iso ⁰ is established. i1. Method according to one of the preceding claims, characterized characterized in that the alkaline catalyst in amounts of -r- to 1: 1500 per mole of the caprolactam is applied. 109844/1791